Sample records for abnormal gas exchange

  1. Pulmonary Gas Exchange Abnormalities in Mild Chronic Obstructive Pulmonary Disease. Implications for Dyspnea and Exercise Intolerance.

    PubMed

    Elbehairy, Amany F; Ciavaglia, Casey E; Webb, Katherine A; Guenette, Jordan A; Jensen, Dennis; Mourad, Sahar M; Neder, J Alberto; O'Donnell, Denis E

    2015-06-15

    Several studies in mild chronic obstructive pulmonary disease (COPD) have shown a higher than normal ventilatory equivalent for carbon dioxide ([Formula: see text]e/[Formula: see text]co2) during exercise. Our objective was to examine pulmonary gas exchange abnormalities and the mechanisms of high [Formula: see text]e/[Formula: see text]co2 in mild COPD and its impact on dyspnea and exercise intolerance. Twenty-two subjects (11 patients with GOLD [Global Initiative for Chronic Obstructive Lung Disease] grade 1B COPD, 11 age-matched healthy control subjects) undertook physiological testing and a symptom-limited incremental cycle exercise test with arterial blood gas collection. Patients (post-bronchodilator FEV1: 94 ± 10% predicted; mean ± SD) had evidence of peripheral airway dysfunction and reduced peak oxygen uptake compared with control subjects (80 ± 18 vs. 113 ± 24% predicted; P<0.05). Arterial blood gases were within the normal range and effective alveolar ventilation was not significantly different from control subjects throughout exercise. The alveolar-arterial O2 tension gradient was elevated at rest and throughout exercise in COPD (P<0.05). [Formula: see text]e/[Formula: see text]co2, dead space to tidal volume ratio (Vd/Vt), and arterial to end-tidal CO2 difference were all higher (P<0.05) in patients with COPD than in control subjects during exercise. In patients with COPD versus control subjects, there was significant dynamic hyperinflation and greater tidal volume constraints (P<0.05). Standardized dyspnea intensity ratings were also higher (P<0.05) in patients with COPD versus control subjects in association with higher ventilatory requirements. Within all subjects, Vd/Vt correlated with the [Formula: see text]e/[Formula: see text]co2 ratio during submaximal exercise (r=0.780, P<0.001). High Vd/Vt was the most consistent gas exchange abnormality in smokers with only mild spirometric abnormalities. Compensatory increases in minute

  2. Impaired gas exchange: accuracy of defining characteristics in children with acute respiratory infection1

    PubMed Central

    Pascoal, Lívia Maia; Lopes, Marcos Venícios de Oliveira; Chaves, Daniel Bruno Resende; Beltrão, Beatriz Amorim; da Silva, Viviane Martins; Monteiro, Flávia Paula Magalhães

    2015-01-01

    OBJECTIVE: to analyze the accuracy of the defining characteristics of the Impaired gas exchange nursing diagnosis in children with acute respiratory infection. METHOD: open prospective cohort study conducted with 136 children monitored for a consecutive period of at least six days and not more than ten days. An instrument based on the defining characteristics of the Impaired gas exchange diagnosis and on literature addressing pulmonary assessment was used to collect data. The accuracy means of all the defining characteristics under study were computed. RESULTS: the Impaired gas exchange diagnosis was present in 42.6% of the children in the first assessment. Hypoxemia was the characteristic that presented the best measures of accuracy. Abnormal breathing presented high sensitivity, while restlessness, cyanosis, and abnormal skin color showed high specificity. All the characteristics presented negative predictive values of 70% and cyanosis stood out by its high positive predictive value. CONCLUSION: hypoxemia was the defining characteristic that presented the best predictive ability to determine Impaired gas exchange. Studies of this nature enable nurses to minimize variability in clinical situations presented by the patient and to identify more precisely the nursing diagnosis that represents the patient's true clinical condition. PMID:26155010

  3. Ventilatory gas exchange and early response to cardiac resynchronization therapy.

    PubMed

    Kim, Chul-Ho; Olson, Lyle J; Shen, Win K; Cha, Yong-Mei; Johnson, Bruce D

    2015-11-01

    Cardiac resynchronization therapy (CRT) is an accepted intervention for chronic heart failure (HF), although approximately 30% of patients are non-responders. The purpose of this study was to determine whether exercise respiratory gas exchange obtained before CRT implantation predicts early response to CRT. Before CRT implantation, patients were assigned to either a mild-moderate group (Mod G, n = 33, age 67 ± 10 years) or a moderate-severe group (Sev G, n = 31, age 67 ± 10 years), based on abnormalities in exercise gas exchange. Severity of impaired gas exchange was based on a score from the measures of VE/VCO(2) slope, resting PETCO(2) and change of PETCO(2) from resting to peak. All measurements were performed before and 3 to 4 months after CRT implantation. Although Mod G did not have improved gas exchange (p > 0.05), Sev G improved significantly (p < 0.05) post-CRT. In addition, Mod G did not show improved right ventricular systolic pressure (RSVP; pre vs post: 37 ± 14 vs 36 ± 11 mm Hg, p > 0.05), yet Sev G showed significantly improved RVSP, by 23% (50 ± 14 vs 42 ± 12 mm Hg, p < 0.05). Both groups had improved left ventricular ejection fraction (p < 0.05), New York Heart Association class (p < 0.05) and quality of life (p < 0.05), but no significant differences were observed between groups (p > 0.05). No significant changes were observed in brain natriuretic peptide in either group post-CRT. Based on pre-CRT implantation ventilatory gas exchange, subjects with the most impaired values appeared to have more improvement post-CRT, possibly associated with a decrease in RVSP. Copyright © 2015 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

  4. Gas Transfer in Cellularized Collagen-Membrane Gas Exchange Devices.

    PubMed

    Lo, Justin H; Bassett, Erik K; Penson, Elliot J N; Hoganson, David M; Vacanti, Joseph P

    2015-08-01

    Chronic lower respiratory disease is highly prevalent in the United States, and there remains a need for alternatives to lung transplant for patients who progress to end-stage lung disease. Portable or implantable gas oxygenators based on microfluidic technologies can address this need, provided they operate both efficiently and biocompatibly. Incorporating biomimetic materials into such devices can help replicate native gas exchange function and additionally support cellular components. In this work, we have developed microfluidic devices that enable blood gas exchange across ultra-thin collagen membranes (as thin as 2 μm). Endothelial, stromal, and parenchymal cells readily adhere to these membranes, and long-term culture with cellular components results in remodeling, reflected by reduced membrane thickness. Functionally, acellular collagen-membrane lung devices can mediate effective gas exchange up to ∼288 mL/min/m(2) of oxygen and ∼685 mL/min/m(2) of carbon dioxide, approaching the gas exchange efficiency noted in the native lung. Testing several configurations of lung devices to explore various physical parameters of the device design, we concluded that thinner membranes and longer gas exchange distances result in improved hemoglobin saturation and increases in pO2. However, in the design space tested, these effects are relatively small compared to the improvement in overall oxygen and carbon dioxide transfer by increasing the blood flow rate. Finally, devices cultured with endothelial and parenchymal cells achieved similar gas exchange rates compared with acellular devices. Biomimetic blood oxygenator design opens the possibility of creating portable or implantable microfluidic devices that achieve efficient gas transfer while also maintaining physiologic conditions.

  5. Incorporating the gas analyzer response time in gas exchange computations.

    PubMed

    Mitchell, R R

    1979-11-01

    A simple method for including the gas analyzer response time in the breath-by-breath computation of gas exchange rates is described. The method uses a difference equation form of a model for the gas analyzer in the computation of oxygen uptake and carbon dioxide production and avoids a numerical differentiation required to correct the gas fraction wave forms. The effect of not accounting for analyzer response time is shown to be a 20% underestimation in gas exchange rate. The present method accurately measures gas exchange rate, is relatively insensitive to measurement errors in the analyzer time constant, and does not significantly increase the computation time.

  6. Impact of airway gas exchange on the multiple inert gas elimination technique: theory.

    PubMed

    Anderson, Joseph C; Hlastala, Michael P

    2010-03-01

    The multiple inert gas elimination technique (MIGET) provides a method for estimating alveolar gas exchange efficiency. Six soluble inert gases are infused into a peripheral vein. Measurements of these gases in breath, arterial blood, and venous blood are interpreted using a mathematical model of alveolar gas exchange (MIGET model) that neglects airway gas exchange. A mathematical model describing airway and alveolar gas exchange predicts that two of these gases, ether and acetone, exchange primarily within the airways. To determine the effect of airway gas exchange on the MIGET, we selected two additional gases, toluene and m-dichlorobenzene, that have the same blood solubility as ether and acetone and minimize airway gas exchange via their low water solubility. The airway-alveolar gas exchange model simulated the exchange of toluene, m-dichlorobenzene, and the six MIGET gases under multiple conditions of alveolar ventilation-to-perfusion, VA/Q, heterogeneity. We increased the importance of airway gas exchange by changing bronchial blood flow, Qbr. From these simulations, we calculated the excretion and retention of the eight inert gases and divided the results into two groups: (1) the standard MIGET gases which included acetone and ether and (2) the modified MIGET gases which included toluene and m-dichlorobenzene. The MIGET mathematical model predicted distributions of ventilation and perfusion for each grouping of gases and multiple perturbations of VA/Q and Qbr. Using the modified MIGET gases, MIGET predicted a smaller dead space fraction, greater mean VA, greater log(SDVA), and more closely matched the imposed VA distribution than that using the standard MIGET gases. Perfusion distributions were relatively unaffected.

  7. Gas Exchange of Algae

    PubMed Central

    Ammann, Elizabeth C. B.; Lynch, Victoria H.

    1967-01-01

    The oxygen production of a photosynthetic gas exchanger containing Chlorella pyrenoidosa (1% packed cell volume) was measured when various concentrations of carbon dioxide were present within the culture unit. The internal carbon dioxide concentrations were obtained by manipulating the entrance gas concentration and the flow rate. Carbon dioxide percentages were monitored by means of electrodes placed directly in the nutrient medium. The concentration of carbon dioxide in the nutrient medium which produced maximal photosynthesis was in the range of 1.5 to 2.5% by volume. Results were unaffected by either the level of carbon dioxide in the entrance gas or the rate of gas flow. Entrance gases containing 2% carbon dioxide flowing at 320 ml/min, 3% carbon dioxide at 135 ml/min, and 4% carbon dioxide at 55 ml/min yielded optimal carbon dioxide concentrations in the particular unit studied. By using carbon dioxide electrodes implanted directly in the gas exchanger to optimize the carbon dioxide concentration throughout the culture medium, it should be possible to design more efficient large-scale units. PMID:4382391

  8. Environmental sensitivity of gas exchange in different-sized trees.

    PubMed

    McDowell, Nate G; Licata, Julian; Bond, Barbara J

    2005-08-01

    The carbon isotope signature (delta13C) of foliar cellulose from sunlit tops of trees typically becomes enriched as trees of the same species in similar environments grow taller, indicative of size-related changes in leaf gas exchange. However, direct measurements of gas exchange in common environmental conditions do not always reveal size-related differences, even when there is a distinct size-related trend in delta13C of the very foliage used for the gas exchange measurements. Since delta13C of foliage predominately reflects gas exchange during spring when carbon is incorporated into leaf cellulose, this implies that gas exchange differences in different-sized trees are most likely to occur in favorable environmental conditions during spring. If gas exchange differs with tree size during wet but not dry conditions, then this further implies that environmental sensitivity of leaf gas exchange varies as a function of tree size. These implications are consistent with theoretical relationships among height, hydraulic conductance and gas exchange. We investigated the environmental sensitivity of gas exchange in different-sized Douglas-fir (Pseudotsuga menziesii) via a detailed process model that specifically incorporates size-related hydraulic conductance [soil-plant-atmosphere (SPA)], and empirical measurements from both wet and dry periods. SPA predicted, and the empirical measurements verified, that differences in gas exchange associated with tree size are greatest in wet and mild environmental conditions and minimal during drought. The results support the hypothesis that annual net carbon assimilation and transpiration of trees are limited by hydraulic capacity as tree size increases, even though at particular points in time there may be no difference in gas exchange between different-sized trees. Maximum net ecosystem exchange occurs in spring in Pacific Northwest forests; therefore, the presence of hydraulic limitations during this period may play a large role

  9. Analysis of factors affecting gas exchange in intravascular blood gas exchanger.

    PubMed

    Niranjan, S C; Clark, J W; San, K Y; Zwischenberger, J B; Bidani, A

    1994-10-01

    A mathematical model of an intravascular hollow-fiber gas-exchange device, called IVOX, has been developed using a Krogh cylinder-like approach with a repeating unit structure comprised of a single fiber with gas flowing through its lumen surrounded by a coaxial cylinder of blood flowing in the opposite direction. Species mass balances on O2 and CO2 result in a nonlinear coupled set of convective-diffusion parabolic partial differential equations that are solved numerically using an alternating-direction implicit finite-difference method. Computed results indicated the presence of a large resistance to gas transport on the external (blood) side of the hollow-fiber exchanger. Increasing gas flow through the device favored CO2 removal from but not O2 addition to blood. Increasing blood flow over the device favored both CO2 removal as well as O2 addition. The rate of CO2 removal increased linearly with the transmural PCO2 gradient imposed across the device. The effect of fiber crimping on blood phase mass transfer resistance was evaluated indirectly by varying species blood diffusivity. Computed results indicated that CO2 excretion by IVOX can be significantly enhanced with improved bulk mixing of vena caval blood around the IVOX fibers.

  10. Gas exchange in avian embryos and hatchlings.

    PubMed

    Mortola, Jacopo P

    2009-08-01

    The avian egg has been proven to be an excellent model for the study of the physical principles and the physiological characteristics of embryonic gas exchange. In recent years, it has become a model for the studies of the prenatal development of pulmonary ventilation, its chemical control and its interaction with extra-pulmonary gas exchange. Differently from mammals, in birds the initiation of pulmonary ventilation and the transition from diffusive to convective gas exchange are gradual and slow-occurring events amenable to detailed investigations. The absence of the placenta and of the mother permits the study of the mechanisms of embryonic adaptation to prenatal perturbations in a way that would be impossible with mammalian preparations. First, this review summarises the general aspects of the natural history of the avian egg that are pertinent to embryonic metabolism, growth and gas exchange and the characteristics of the structures participating in gas exchange. Then, the review focuses on the embryonic development of pulmonary ventilation, its regulation in relation to the embryo's environment and metabolic state, the effects that acute or sustained changes in embryonic temperature or oxygenation can have on growth, metabolism and ventilatory control.

  11. BOREAS TE-12 Leaf Gas Exchange Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Arkebauer, Timothy J.; Yang, Litao

    2000-01-01

    The BOREAS TE-12 team collected several data sets in support of its efforts to characterize and interpret information on the reflectance, transmittance, and gas exchange of boreal vegetation. This data set contains measurements of leaf gas exchange conducted in the SSA during the growing seasons of 1994 and 1995 using a portable gas exchange system. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Center (DAAC).

  12. On factors influencing air-water gas exchange in emergent wetlands

    USGS Publications Warehouse

    Ho, David T.; Engel, Victor C.; Ferron, Sara; Hickman, Benjamin; Choi, Jay; Harvey, Judson W.

    2018-01-01

    Knowledge of gas exchange in wetlands is important in order to determine fluxes of climatically and biogeochemically important trace gases and to conduct mass balances for metabolism studies. Very few studies have been conducted to quantify gas transfer velocities in wetlands, and many wind speed/gas exchange parameterizations used in oceanographic or limnological settings are inappropriate under conditions found in wetlands. Here six measurements of gas transfer velocities are made with SF6 tracer release experiments in three different years in the Everglades, a subtropical peatland with surface water flowing through emergent vegetation. The experiments were conducted under different flow conditions and with different amounts of emergent vegetation to determine the influence of wind, rain, water flow, waterside thermal convection, and vegetation on air-water gas exchange in wetlands. Measured gas transfer velocities under the different conditions ranged from 1.1 cm h−1 during baseline conditions to 3.2 cm h−1 when rain and water flow rates were high. Commonly used wind speed/gas exchange relationships would overestimate the gas transfer velocity by a factor of 1.2 to 6.8. Gas exchange due to thermal convection was relatively constant and accounted for 14 to 51% of the total measured gas exchange. Differences in rain and water flow among the different years were responsible for the variability in gas exchange, with flow accounting for 37 to 77% of the gas exchange, and rain responsible for up to 40%.

  13. Automated measurement of respiratory gas exchange by an inert gas dilution technique

    NASA Technical Reports Server (NTRS)

    Sawin, C. F.; Rummel, J. A.; Michel, E. L.

    1974-01-01

    A respiratory gas analyzer (RGA) has been developed wherein a mass spectrometer is the sole transducer required for measurement of respiratory gas exchange. The mass spectrometer maintains all signals in absolute phase relationships, precluding the need to synchronize flow and gas composition as required in other systems. The RGA system was evaluated by comparison with the Douglas bag technique. The RGA system established the feasibility of the inert gas dilution method for measuring breath-by-breath respiratory gas exchange. This breath-by-breath analytical capability permits detailed study of transient respiratory responses to exercise.

  14. Perfluorocarbon-associated gas exchange in normal and acid-injured large sheep.

    PubMed

    Hernan, L J; Fuhrman, B P; Kaiser, R E; Penfil, S; Foley, C; Papo, M C; Leach, C L

    1996-03-01

    We hypothesized that a) perfluorocarbon-associated gas exchange could be accomplished in normal large sheep; b) the determinants of gas exchange would be similar during perfluorocarbon-associated gas exchange and conventional gas ventilation; c)in large animals with lung injury, perfluorocarbon-associated gas exchange could be used to enhance gas exchange without adverse effects on hemodynamics; and d) the large animal with lung injury could be supported with an FIO2 of <1.0 during perfluorocarbon-associated gas exchange. Prospective, observational animal study and prospective randomized, controlled animal study. An animal laboratory in a university setting. Thirty adult ewes. Five normal ewes (61.0 +/- 4.0 kg) underwent perfluorocarbon-associated gas exchange to ascertain the effects of tidal volume, end-inspiratory pressure, and positive end-expiratory pressure (PEEP) on oxygenation. Respiratory rate, tidal volume, and minute ventilation were studied to determine their effects on CO2 clearance. Sheep, weighing 58.9 +/- 8.3 kg, had lung injury induced by instilling 2 mL/kg of 0.05 Normal hydrochloric acid into the trachea. Five minutes after injury, PEEP was increased to 10 cm H2O. Ten minutes after injury, sheep with Pao2 values of <100 torr (<13.3 kPa) were randomized to continue gas ventilation (control, n=9) or to institute perfluorocarbon-associated gas exchange (n=9) by instilling 1.6 L of unoxygenated perflubron into the trachea and resuming gas ventilation. Blood gas and hemodynamic measurements were obtained throughout the 4-hr study. Both tidal volume and end-inspiratory pressure influenced oxygenation in normal sheep during perfluorocarbon-associated gas exchange. Minute ventilation determined CO2 clearance during perfluorocarbon-associated gas exchange in normal sheep. After acid aspiration lung injury, perfluorocarbon-associated gas exchange increased PaO2 and reduced intrapulmonary shunt fraction. Hypoxia and intrapulmonary shunting were unabated

  15. Pulmonary gas exchange in acute respiratory failure.

    PubMed

    Rodriguez-Roisin, R

    1994-01-01

    The principal function of the lung is to facilitate the exchange of the respiratory gases, oxygen (O2) and carbon dioxide (CO2). When the lung fails as a gas exchanger respiratory failure ensues. Clinically, it is generally accepted that an arterial oxygen tension (PaO2) of less than 60 mmHg or a PaCO2 of greater than 50 mmHg, or both, whilst breathing room air are values consistent with the concept of respiratory failure. This article will deal, firstly, with some basic aspects of the physiology of pulmonary gas exchange and more specifically on the measurement of ventilation-perfusion (VA/Q) relationships, the most influential factor determining hypoxaemia. The second part highlights the most important findings on pulmonary gas exchange in the adult respiratory distress syndrome (ARDS) and other common acute respiratory failure conditions, such as pneumonia, acute exacerbation of chronic obstructive pulmonary disease (COPD) and status asthmaticus, based on the data obtained by means of the multiple inert gas elimination approach, a technique which gives a detailed picture of VA/Q ratio distributions.

  16. BOREAS TF-11 SSA-Fen Leaf Gas Exchange Data

    NASA Technical Reports Server (NTRS)

    Arkebauer, Timothy J.; Hall, Forrest G. (Editor); Knapp, David E. (Editor)

    2000-01-01

    The BOREAS TF-11 team gathered a variety of data to complement its tower flux measurements collected at the SSA-Fen site. This data set contains single-leaf gas exchange data from the SSA-Fen site during 1994 and 1995. These leaf gas exchange properties were measured for the dominant vascular plants using portable gas exchange systems. The data are stored in tabular ASCII files.

  17. Use of argon to measure gas exchange in turbulent mountain streams

    NASA Astrophysics Data System (ADS)

    Hall, Robert O., Jr.; Madinger, Hilary L.

    2018-05-01

    Gas exchange is a parameter needed in stream metabolism and trace gas emissions models. One way to estimate gas exchange is via measuring the decline of added tracer gases such as sulfur hexafluoride (SF6). Estimates of oxygen (O2) gas exchange derived from SF6 additions require scaling via Schmidt number (Sc) ratio, but this scaling is uncertain under conditions of high gas exchange via bubbles because scaling depends on gas solubility as well as Sc. Because argon (Ar) and O2 have nearly identical Schmidt numbers and solubility, Ar may be a useful tracer gas for estimating stream O2 exchange. Here we compared rates of gas exchange measured via Ar and SF6 for turbulent mountain streams in Wyoming, USA. We measured Ar as the ratio of Ar : N2 using a membrane inlet mass spectrometer (MIMS). Normalizing to N2 confers higher precision than simply measuring [Ar] alone. We consistently enriched streams with Ar from 1 to 18 % of ambient Ar concentration and could estimate gas exchange rate using an exponential decline model. The mean ratio of gas exchange of Ar relative to SF6 was 1.8 (credible interval 1.1 to 2.5) compared to the theoretical estimate 1.35, showing that using SF6 would have underestimated exchange of Ar. Steep streams (slopes 11-12 %) had high rates of gas exchange velocity normalized to Sc = 600 (k600, 57-210 m d-1), and slope strongly predicted variation in k600 among all streams. We suggest that Ar is a useful tracer because it is easily measured, requires no scaling assumptions to estimate rates of O2 exchange, and is not an intense greenhouse gas as is SF6. We caution that scaling from rates of either Ar or SF6 gas exchange to CO2 is uncertain due to solubility effects in conditions of bubble-mediated gas transfer.

  18. A Controlled Environment System For Measuring Plant-Atmosphere Gas Exchange

    Treesearch

    James M. Brown

    1975-01-01

    Describes an inexpensive, efficient system for measuring plant-atmosphere gas exchange. Designed to measure transpiration from potted tree seedlings, it is readily adaptable for measuring other gas exchanges or gas exchange by plant parts. Light level, air and root temperature can be precisely controlled at minimum cost.

  19. Efficient gas exchange between a boreal river and the atmosphere

    NASA Astrophysics Data System (ADS)

    Huotari, Jussi; Haapanala, Sami; Pumpanen, Jukka; Vesala, Timo; Ojala, Anne

    2013-11-01

    largest uncertainties in accurately resolving the role of rivers and streams in carbon cycling stem from difficulties in determining gas exchange between water and the atmosphere. So far, estimates for river-atmosphere gas exchange have lacked direct ecosystem-scale flux measurements not disturbing gas exchange across the air-water interface. We conducted the first direct riverine gas exchange measurements with eddy covariance in tandem with continuous surface water CO2 measurements in a large boreal river for 30 days. Our measured gas transfer velocity was, on average, 20.8 cm h-1, which is clearly higher than the model estimates based on river channel morphology and water velocity, whereas our floating chambers gave comparable values at 17.3 cm h-1. These results demonstrate that present estimates for riverine CO2 emissions are very likely too low. This result is also relevant to any other gases emitted, as their diffusive exchange rates are similarly proportional to gas transfer velocity.

  20. Spume Drops: Their Potential Role in Air-Sea Gas Exchange

    NASA Astrophysics Data System (ADS)

    Monahan, Edward C.; Staniec, Allison; Vlahos, Penny

    2017-12-01

    After summarizing the time scales defining the change of the physical properties of spume and other droplets cast up from the sea surface, the time scales governing drop-atmosphere gas exchange are compared. Following a broad review of the spume drop production functions described in the literature, a subset of these functions is selected via objective criteria, to represent typical, upper bound, and lower bound production functions. Three complementary mechanisms driving spume-atmosphere gas exchange are described, and one is then used to estimate the relative importance, over a broad range of wind speeds, of this spume drop mechanism compared to the conventional, diffusional, sea surface mechanism in air-sea gas exchange. While remaining uncertainties in the wind dependence of the spume drop production flux, and in the immediate sea surface gas flux, preclude a definitive conclusion, the findings of this study strongly suggest that, at high wind speeds (>20 m s-1 for dimethyl sulfide and >30 m s-1 for gases such a carbon dioxide), spume drops do make a significant contribution to air-sea gas exchange.Plain Language SummaryThis paper evaluates the existing spume drop generation functions available to date and selects a reasonable upper, lower and mid range function that are reasonable for use in air sea <span class="hlt">exchange</span> models. Based on these the contribution of spume drops to overall air sea <span class="hlt">gas</span> <span class="hlt">exchange</span> at different wind speeds is then evaluated to determine the % contribution of spume. Generally below 20ms-1 spume drops contribute <1% of <span class="hlt">gas</span> <span class="hlt">exchange</span> but may account for a significant amount of <span class="hlt">gas</span> <span class="hlt">exchange</span> at higher wind speeds.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li class="active"><span>1</span></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_1 --> <div id="page_2" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li class="active"><span>2</span></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="21"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29427536','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29427536"><span>Impaired <span class="hlt">Gas</span> <span class="hlt">Exchange</span>: Prognostic Clinical Indicators of Short-Term Survival in Children with Acute Respiratory Infection.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pascoal, Lívia Maia; de Oliveira Lopes, Marcos Venícios; Chaves, Daniel Bruno Resende; Beltrão, Beatriz Amorim; Nunes, Marília Mendes; da Silva, Viviane Martins; de Sousa Freire, Vanessa Emille Carvalho</p> <p>2018-02-10</p> <p>To establish prognostic indicators of survival for impaired <span class="hlt">gas</span> <span class="hlt">exchange</span> (IGE) (00030). Secondary analysis of data from an open prospective cohort developed with a group of 136 children with acute respiratory infection (ARI). On Day 1, IGE (00030) was present in 42.6% of the sample. New cases arose until the last day of evaluation. With regards to defining characteristics, only hypoxemia and <span class="hlt">abnormal</span> skin color were associated with a higher risk of developing diagnosis. Children with ARI who exhibit hypoxemia and <span class="hlt">abnormal</span> skin color had a worse prognosis for IGE (00030). Nurses can use the research findings as a predictive marker of the evolution of the patient's health status. © 2018 NANDA International, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=546779','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=546779"><span><span class="hlt">Gas</span> <span class="hlt">Exchange</span> of Algae</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ammann, Elizabeth C. B.; Lynch, Victoria H.</p> <p>1966-01-01</p> <p>Changes in the oxygen partial pressure of air over the range of 8 to 258 mm of Hg did not adversely affect the photosynthetic capacity of Chlorella pyrenoidosa. <span class="hlt">Gas</span> <span class="hlt">exchange</span> and growth measurements remained constant for 3-week periods and were similar to air controls (oxygen pressure of 160 mm of Hg). Oxygen partial pressures of 532 and 745 mm of Hg had an adverse effect on algal metabolism. Carbon dioxide consumption was 24% lower in the <span class="hlt">gas</span> mixture containing oxygen at a pressure 532 mm of Hg than in the air control, and the growth rate was slightly reduced. Oxygen at a partial pressure of 745 mm of Hg decreased the photosynthetic rate 39% and the growth rate 37% over the corresponding rates in air. The lowered metabolic rates remained constant during 14 days of measurements, and the effect was reversible after this time. Substitution of helium or argon for the nitrogen in air had no effect on oxygen production, carbon dioxide consumption, or growth rate for 3-week periods. All measurements were made at a total pressure of 760 mm of Hg, and all <span class="hlt">gas</span> mixtures were enriched with 2% carbon dioxide. Thus, the physiological functioning and reliability of a photosynthetic <span class="hlt">gas</span> <span class="hlt">exchanger</span> should not be adversely affected by: (i) oxygen partial pressures ranging from 8 to 258 mm of Hg; (ii) the use of pure oxygen at reduced total pressure (155 to 258 mm of Hg) unless pressure per se affects photosynthesis, or (iii) the inclusion of helium or argon in the <span class="hlt">gas</span> environment (up to a partial pressure of 595 mm of Hg). PMID:5927028</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B51F0483P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B51F0483P"><span>Automatable Measurement of <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Rate in Streams: Oxygen-Carbon Method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pennington, R.; Haggerty, R.; Argerich, A.; Wondzell, S. M.</p> <p>2015-12-01</p> <p><span class="hlt">Gas</span> <span class="hlt">exchange</span> rates between streams and the atmosphere are critically important to measurement of in-stream ecologic processes, as well as fate and transport of hazardous pollutants such as mercury and PCBs. Methods to estimate <span class="hlt">gas</span> <span class="hlt">exchange</span> rates include empirical relations to hydraulics, and direct injection of a tracer <span class="hlt">gas</span> such as propane or SF6. Empirical relations are inconsistent and inaccurate, particularly for lower order, high-roughness streams. <span class="hlt">Gas</span> injections are labor-intensive, and measured <span class="hlt">gas</span> <span class="hlt">exchange</span> rates are difficult to extrapolate in time since they change with discharge and stream geometry. We propose a novel method for calculation of <span class="hlt">gas</span> <span class="hlt">exchange</span> rates utilizing O2, pCO2, pH, and temperature data. Measurements, which can be automated using data loggers and probes, are made on the upstream and downstream end of the study reach. <span class="hlt">Gas</span> <span class="hlt">exchange</span> rates are then calculated from a solution to the transport equations for oxygen and dissolved inorganic carbon. Field tests in steep, low order, high roughness streams of the HJ Andrews Experimental Forest indicate the method to be viable along stream reaches with high downstream <span class="hlt">gas</span> concentration gradients and high rates of <span class="hlt">gas</span> transfer velocity. Automated and continuous collection of oxygen and carbonate chemistry data is increasingly common, thus the method may be used to estimate <span class="hlt">gas</span> <span class="hlt">exchange</span> rates through time, and is well suited for interactivity with databases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29452100','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29452100"><span>A New, Noninvasive Method of Measuring Impaired Pulmonary <span class="hlt">Gas</span> <span class="hlt">Exchange</span> in Lung Disease: An Outpatient Study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>West, John B; Crouch, Daniel R; Fine, Janelle M; Makadia, Dipen; Wang, Daniel L; Prisk, G Kim</p> <p>2018-02-13</p> <p>It would be valuable to have a noninvasive method of measuring impaired pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> in patients with lung disease and thus reduce the need for repeated arterial punctures. This study reports the results of using a new test in a group of outpatients attending a pulmonary clinic. Inspired and expired partial pressure of oxygen (PO 2 ) and Pco 2 are continually measured by small, rapidly responding analyzers. The arterial PO 2 is calculated from the oximeter blood oxygen saturation level and the oxygen dissociation curve. The PO 2 difference between the end-tidal <span class="hlt">gas</span> and the calculated arterial value is called the oxygen deficit. Studies on 17 patients with a variety of pulmonary diseases are reported. The mean ± SE oxygen deficit was 48.7 ± 3.1 mm Hg. This finding can be contrasted with a mean oxygen deficit of 4.0 ± 0.88 mm Hg in a group of 31 normal subjects who were previously studied (P < .0001). The analysis emphasizes the value of measuring the composition of alveolar <span class="hlt">gas</span> in determining ventilation-perfusion ratio inequality. This factor is largely ignored in the classic index of impaired pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> using the ideal alveolar PO 2 to calculate the alveolar-arterial oxygen gradient. The results previously reported in normal subjects and the present studies suggest that this new noninvasive test will be valuable in assessing <span class="hlt">abnormal</span> <span class="hlt">gas</span> <span class="hlt">exchange</span> in the clinical setting. Copyright © 2018 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOS.A34C2670V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOS.A34C2670V"><span>Setting an Upper Limit on <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Through Sea-Spray</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vlahos, P.; Monahan, E. C.; Andreas, E. L.</p> <p>2016-02-01</p> <p>Air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> parameterization is critical to understanding both climate forcing and feedbacks and is key in biogeochemistry cycles. Models based on wind speed have provided empirical estimates of <span class="hlt">gas</span> <span class="hlt">exchange</span> that are useful though it is likely that at high wind speeds of over 10 m/s there are important <span class="hlt">gas</span> <span class="hlt">exchange</span> parameters including bubbles and sea spray that have not been well constrained. Here we address the sea-spray component of <span class="hlt">gas</span> <span class="hlt">exchange</span> at these high wind speeds to set sn upper boundary condition for the <span class="hlt">gas</span> <span class="hlt">exchange</span> of the six model gases including; nobel gases helium, neon and argon, diatomic gases nitrogen and oxygen and finally, the more complex <span class="hlt">gas</span> carbon dioxide. Estimates are based on the spray generation function of Andreas and Monahan and the gases are tested under three scenarios including 100 percent saturation and complete droplet evaporation, 100 percent saturation and a more realistic scenario in which a fraction of droplets evaporate completely, a fraction evaporate to some degree and a fraction returns to the water side without significant evaporation. Finally the latter scenario is applied to representative under saturated concentrations of the gases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2889562','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2889562"><span>Universal model for water costs of <span class="hlt">gas</span> <span class="hlt">exchange</span> by animals and plants</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Woods, H. Arthur; Smith, Jennifer N.</p> <p>2010-01-01</p> <p>For terrestrial animals and plants, a fundamental cost of living is water vapor lost to the atmosphere during <span class="hlt">exchange</span> of metabolic gases. Here, by bringing together previously developed models for specific taxa, we integrate properties common to all terrestrial <span class="hlt">gas</span> <span class="hlt">exchangers</span> into a universal model of water loss. The model predicts that water loss scales to <span class="hlt">gas</span> <span class="hlt">exchange</span> with an exponent of 1 and that the amount of water lost per unit of <span class="hlt">gas</span> <span class="hlt">exchanged</span> depends on several factors: the surface temperature of the respiratory system near the outside of the organism, the <span class="hlt">gas</span> consumed (oxygen or carbon dioxide), the steepness of the gradients for <span class="hlt">gas</span> and vapor, and the transport mode (convective or diffusive). Model predictions were largely confirmed by data on 202 species in five taxa—insects, birds, bird eggs, mammals, and plants—spanning nine orders of magnitude in rate of <span class="hlt">gas</span> <span class="hlt">exchange</span>. Discrepancies between model predictions and data seemed to arise from biologically interesting violations of model assumptions, which emphasizes how poorly we understand <span class="hlt">gas</span> <span class="hlt">exchange</span> in some taxa. The universal model provides a unified conceptual framework for analyzing <span class="hlt">exchange</span>-associated water losses across taxa with radically different metabolic and <span class="hlt">exchange</span> systems. PMID:20404161</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20404161','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20404161"><span>Universal model for water costs of <span class="hlt">gas</span> <span class="hlt">exchange</span> by animals and plants.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Woods, H Arthur; Smith, Jennifer N</p> <p>2010-05-04</p> <p>For terrestrial animals and plants, a fundamental cost of living is water vapor lost to the atmosphere during <span class="hlt">exchange</span> of metabolic gases. Here, by bringing together previously developed models for specific taxa, we integrate properties common to all terrestrial <span class="hlt">gas</span> <span class="hlt">exchangers</span> into a universal model of water loss. The model predicts that water loss scales to <span class="hlt">gas</span> <span class="hlt">exchange</span> with an exponent of 1 and that the amount of water lost per unit of <span class="hlt">gas</span> <span class="hlt">exchanged</span> depends on several factors: the surface temperature of the respiratory system near the outside of the organism, the <span class="hlt">gas</span> consumed (oxygen or carbon dioxide), the steepness of the gradients for <span class="hlt">gas</span> and vapor, and the transport mode (convective or diffusive). Model predictions were largely confirmed by data on 202 species in five taxa--insects, birds, bird eggs, mammals, and plants--spanning nine orders of magnitude in rate of <span class="hlt">gas</span> <span class="hlt">exchange</span>. Discrepancies between model predictions and data seemed to arise from biologically interesting violations of model assumptions, which emphasizes how poorly we understand <span class="hlt">gas</span> <span class="hlt">exchange</span> in some taxa. The universal model provides a unified conceptual framework for analyzing <span class="hlt">exchange</span>-associated water losses across taxa with radically different metabolic and <span class="hlt">exchange</span> systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?direntryid=315010&keyword=climate%20change&subject=climate%20change%20research&showcriteria=2&fed_org_id=111&datebeginpublishedpresented=03/10/2012&dateendpublishedpresented=03/10/2017&sortby=pubdateyear','PESTICIDES'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?direntryid=315010&keyword=climate%20change&subject=climate%20change%20research&showcriteria=2&fed_org_id=111&datebeginpublishedpresented=03/10/2012&dateendpublishedpresented=03/10/2017&sortby=pubdateyear"><span>A dynamic leaf <span class="hlt">gas-exchange</span> strategy is conserved in woody ...</span></a></p> <p><a target="_blank" href="http://www.epa.gov/pesticides/search.htm">EPA Pesticide Factsheets</a></p> <p></p> <p></p> <p>Rising atmospheric [CO2], ca, is expected to affect stomatal regulation of leaf <span class="hlt">gas-exchange</span> of woody plants, thus influencing energy fluxes as well as carbon (C), water and nutrient cycling of forests. Researchers have reported that stomata regulate leaf <span class="hlt">gas-exchange</span> around “set points” that include a constant leaf internal [CO2], ci, a constant drawdown in CO2 (ca - ci), and a constant ci/ca. Because these set points can result in drastically different consequences for leaf <span class="hlt">gas-exchange</span>, it will be essential for the accuracy of Earth systems models that generalizable patterns in leaf <span class="hlt">gas-exchange</span> responses to ca be identified if any do exist. We hypothesized that the concept of optimal stomatal behavior, exemplified by woody plants shifting along a continuum of these set point strategies, would provide a unifying framework for understanding leaf <span class="hlt">gas-exchange</span> responses to ca. We analyzed studies reporting C stable isotope ratio (δ13C) or photosynthetic discrimination (∆13C) from woody plant taxa that grew across ca spanning at least 100 ppm for each species investigated. From these data we calculated ci, and in combination with known or estimated ca, leaf <span class="hlt">gas-exchange</span> regulation strategies were assessed. Overall, our analyses does not support the hypothesis that trees are canalized towards any of the proposed set points, particularly so for a constant ci. Rather, the results are consistent with the hypothesis that stomatal optimization regulates leaf <span class="hlt">gas</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28965822','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28965822"><span>A new method for noninvasive measurement of pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> using expired <span class="hlt">gas</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>West, John B; Prisk, G Kim</p> <p>2018-01-01</p> <p>Measurement of the <span class="hlt">gas</span> <span class="hlt">exchange</span> efficiency of the lung is often required in the practice of pulmonary medicine and in other settings. The traditional standard is the values of the PO2, PCO2, and pH of arterial blood. However arterial puncture requires technical expertise, is invasive, uncomfortable for the patient, and expensive. Here we describe how the composition of expired <span class="hlt">gas</span> can be used in conjunction with pulse oximetry to obtain useful measures of <span class="hlt">gas</span> <span class="hlt">exchange</span> efficiency. The new procedure is noninvasive, well tolerated by the patient, and takes only a few minutes. It could be particularly useful when repeated measurements of pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> are required. One product of the procedure is the difference between the PO2 of end-tidal alveolar <span class="hlt">gas</span> and the calculated PO2 of arterial blood. This measurement is related to the classical alveolar-arterial PO2 difference based on ideal alveolar <span class="hlt">gas</span>. However that traditional index is heavily influenced by lung units with low ventilation-perfusion ratios, whereas the new index has a broader physiological basis because it includes contributions from the whole lung. Copyright © 2017 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009HMT....46..175M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009HMT....46..175M"><span>High temperature heat <span class="hlt">exchanger</span> studies for applications to <span class="hlt">gas</span> turbines</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Min, June Kee; Jeong, Ji Hwan; Ha, Man Yeong; Kim, Kui Soon</p> <p>2009-12-01</p> <p>Growing demand for environmentally friendly aero <span class="hlt">gas</span>-turbine engines with lower emissions and improved specific fuel consumption can be met by incorporating heat <span class="hlt">exchangers</span> into <span class="hlt">gas</span> turbines. Relevant researches in such areas as the design of a heat <span class="hlt">exchanger</span> matrix, materials selection, manufacturing technology, and optimization by a variety of researchers have been reviewed in this paper. Based on results reported in previous studies, potential heat <span class="hlt">exchanger</span> designs for an aero <span class="hlt">gas</span> turbine recuperator, intercooler, and cooling-air cooler are suggested.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010005746','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010005746"><span>BOREAS TE-5 Leaf <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Ehleriinger, Jim; Brooks, J. Renee; Flanagan, Larry</p> <p>2000-01-01</p> <p>The BOREAS TE-5 team collected measurements in the NSA and SSA on <span class="hlt">gas</span> <span class="hlt">exchange</span>, <span class="hlt">gas</span> composition, and tree growth. The leaf photosynthetic <span class="hlt">gas</span> <span class="hlt">exchange</span> data were collected in the BOREAS NSA and the SSA from 06-Jun- 1994 to 13-Sep- 1994 using a LI-COR 6200 portable photosynthesis system. The data were collected to compare the photosynthetic capacity, stomata] conductance, and leaf intercellular CO, concentrations among the major tree species at the BOREAS sites. The data are average values from diurnal measurements on the upper canopy foliage (sun leaves). The data are available in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Activity Archive Center (DAAC).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21141036','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21141036"><span>Advances in quantifying air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> and environmental forcing.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wanninkhof, Rik; Asher, William E; Ho, David T; Sweeney, Colm; McGillis, Wade R</p> <p>2009-01-01</p> <p>The past decade has seen a substantial amount of research on air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> and its environmental controls. These studies have significantly advanced the understanding of processes that control <span class="hlt">gas</span> transfer, led to higher quality field measurements, and improved estimates of the flux of climate-relevant gases between the ocean and atmosphere. This review discusses the fundamental principles of air-sea <span class="hlt">gas</span> transfer and recent developments in <span class="hlt">gas</span> transfer theory, parameterizations, and measurement techniques in the context of the <span class="hlt">exchange</span> of carbon dioxide. However, much of this discussion is applicable to any sparingly soluble, non-reactive <span class="hlt">gas</span>. We show how the use of global variables of environmental forcing that have recently become available and <span class="hlt">gas</span> <span class="hlt">exchange</span> relationships that incorporate the main forcing factors will lead to improved estimates of global and regional air-sea <span class="hlt">gas</span> fluxes based on better fundamental physical, chemical, and biological foundations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017BGeo...14.5595B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017BGeo...14.5595B"><span>Continuous measurement of air-water <span class="hlt">gas</span> <span class="hlt">exchange</span> by underwater eddy covariance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Berg, Peter; Pace, Michael L.</p> <p>2017-12-01</p> <p><span class="hlt">Exchange</span> of gases, such as O2, CO2, and CH4, over the air-water interface is an important component in aquatic ecosystem studies, but <span class="hlt">exchange</span> rates are typically measured or estimated with substantial uncertainties. This diminishes the precision of common ecosystem assessments associated with <span class="hlt">gas</span> <span class="hlt">exchanges</span> such as primary production, respiration, and greenhouse <span class="hlt">gas</span> emission. Here, we used the aquatic eddy covariance technique - originally developed for benthic O2 flux measurements - right below the air-water interface (˜ 4 cm) to determine <span class="hlt">gas</span> <span class="hlt">exchange</span> rates and coefficients. Using an acoustic Doppler velocimeter and a fast-responding dual O2-temperature sensor mounted on a floating platform the 3-D water velocity, O2 concentration, and temperature were measured at high-speed (64 Hz). By combining these data, concurrent vertical fluxes of O2 and heat across the air-water interface were derived, and <span class="hlt">gas</span> <span class="hlt">exchange</span> coefficients were calculated from the former. Proof-of-concept deployments at different river sites gave standard <span class="hlt">gas</span> <span class="hlt">exchange</span> coefficients (k600) in the range of published values. A 40 h long deployment revealed a distinct diurnal pattern in air-water <span class="hlt">exchange</span> of O2 that was controlled largely by physical processes (e.g., diurnal variations in air temperature and associated air-water heat fluxes) and not by biological activity (primary production and respiration). This physical control of <span class="hlt">gas</span> <span class="hlt">exchange</span> can be prevalent in lotic systems and adds uncertainty to assessments of biological activity that are based on measured water column O2 concentration changes. For example, in the 40 h deployment, there was near-constant river flow and insignificant winds - two main drivers of lotic <span class="hlt">gas</span> <span class="hlt">exchange</span> - but we found <span class="hlt">gas</span> <span class="hlt">exchange</span> coefficients that varied by several fold. This was presumably caused by the formation and erosion of vertical temperature-density gradients in the surface water driven by the heat flux into or out of the river that affected the turbulent</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1980Tell...32..470H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1980Tell...32..470H"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span> across the air-sea interface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hasse, L.; Liss, P. S.</p> <p>1980-10-01</p> <p>The physics of <span class="hlt">gas</span> <span class="hlt">exchange</span> at the air-sea interface are reviewed. In order to describe the transfer of gases in the liquid near the boundary, a molecular plus eddy diffusivity concept is used, which has been found useful for smooth flow over solid surfaces. From consideration of the boundary conditions, a similar dependence of eddy diffusivity on distance from the interface can be derived for the flow beneath a <span class="hlt">gas</span>/liquid interface, at least in the absence of waves. The influence of waves is then discussed. It is evident from scale considerations that the effect of gravity waves is small. It is known from wind tunnel work that capillary waves enhance <span class="hlt">gas</span> transfer considerably. The existing hypotheses are apparently not sufficient to explain the observations. Examination of field data is even more frustrating since the data do not show the expected increase of <span class="hlt">gas</span> <span class="hlt">exchange</span> with wind speed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29593081','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29593081"><span>Cuticular <span class="hlt">gas</span> <span class="hlt">exchange</span> by Antarctic sea spiders.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lane, Steven J; Moran, Amy L; Shishido, Caitlin M; Tobalske, Bret W; Woods, H Arthur</p> <p>2018-04-25</p> <p>Many marine organisms and life stages lack specialized respiratory structures, like gills, and rely instead on cutaneous respiration, which they facilitate by having thin integuments. This respiratory mode may limit body size, especially if the integument also functions in support or locomotion. Pycnogonids, or sea spiders, are marine arthropods that lack gills and rely on cutaneous respiration but still grow to large sizes. Their cuticle contains pores, which may play a role in <span class="hlt">gas</span> <span class="hlt">exchange</span>. Here, we examined alternative paths of <span class="hlt">gas</span> <span class="hlt">exchange</span> in sea spiders: (1) oxygen diffuses across pores in the cuticle, a common mechanism in terrestrial eggshells, (2) oxygen diffuses directly across the cuticle, a common mechanism in small aquatic insects, or (3) oxygen diffuses across both pores and cuticle. We examined these possibilities by modeling diffusive oxygen fluxes across all pores in the body of sea spiders and asking whether those fluxes differed from measured metabolic rates. We estimated fluxes across pores using Fick's law parameterized with measurements of pore morphology and oxygen gradients. Modeled oxygen fluxes through pores closely matched oxygen consumption across a range of body sizes, which means the pores facilitate oxygen diffusion. Furthermore, pore volume scaled hypermetrically with body size, which helps larger species facilitate greater diffusive oxygen fluxes across their cuticle. This likely presents a functional trade-off between <span class="hlt">gas</span> <span class="hlt">exchange</span> and structural support, in which the cuticle must be thick enough to prevent buckling due to external forces but porous enough to allow sufficient <span class="hlt">gas</span> <span class="hlt">exchange</span>. © 2018. Published by The Company of Biologists Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1570919','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1570919"><span>Structure, function and evolution of the <span class="hlt">gas</span> <span class="hlt">exchangers</span>: comparative perspectives</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Maina, JN</p> <p>2002-01-01</p> <p>Over the evolutionary continuum, animals have faced similar fundamental challenges of acquiring molecular oxygen for aerobic metabolism. Under limitations and constraints imposed by factors such as phylogeny, behaviour, body size and environment, they have responded differently in founding optimal respiratory structures. A quintessence of the aphorism that ‘necessity is the mother of invention’, <span class="hlt">gas</span> <span class="hlt">exchangers</span> have been inaugurated through stiff cost–benefit analyses that have evoked transaction of trade-offs and compromises. Cogent structural–functional correlations occur in constructions of <span class="hlt">gas</span> <span class="hlt">exchangers</span>: within and between taxa, morphological complexity and respiratory efficiency increase with metabolic capacities and oxygen needs. Highly active, small endotherms have relatively better-refined <span class="hlt">gas</span> <span class="hlt">exchangers</span> compared with large, inactive ectotherms. Respiratory structures have developed from the plain cell membrane of the primeval prokaryotic unicells to complex multifunctional ones ofthe modern Metazoa. Regarding the respiratory medium used to extract oxygen from, animal life has had only two choices – water or air – within the biological range of temperature and pressure the only naturally occurring respirable fluids. In rarer cases, certain animalshave adapted to using both media. Gills (evaginated <span class="hlt">gas</span> <span class="hlt">exchangers</span>) are the primordial respiratory organs: they are the archetypal water breathing organs. Lungs (invaginated <span class="hlt">gas</span> <span class="hlt">exchangers</span>) are the model air breathing organs. Bimodal (transitional) breathers occupy the water–air interface. Presentation and exposure of external (water/air) and internal (haemolymph/blood) respiratory media, features determined by geometric arrangement of the conduits, are important features for <span class="hlt">gas</span> <span class="hlt">exchange</span> efficiency: counter-current, cross-current, uniform pool and infinite pool designs have variably developed. PMID:12430953</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/7203850-enhance-gas-processing-reflux-heat-exchangers','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/7203850-enhance-gas-processing-reflux-heat-exchangers"><span>Enhance <span class="hlt">gas</span> processing with reflux heat-<span class="hlt">exchangers</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Finn, A.J.</p> <p>1994-05-01</p> <p>Despite recent successes of membrane-based separations in low-throughput applications, cryogenic processing remains the best route for separating and purifying <span class="hlt">gas</span> mixtures, especially when high recoveries are required. Now conventional units are being modified to yield even higher recoveries at lower costs. Throughout the chemical process industries (CPI), this is being accomplished with reflux or plate-fin <span class="hlt">exchangers</span>, especially for processing of natural <span class="hlt">gas</span>, and offgases from refineries and petrochemical facilities. The concept of utilizing a heat <span class="hlt">exchanger</span> as a multi stage rectification device is not new. However, only in the last fifteen years or so has accurate design of reflux exchangersmore » become feasible. Also helpful have been the availability of prediction techniques for high-quality thermodynamic data, and process simulators that can rapidly solve the complex material, equilibrium and enthalpy relationships involved in simulating the performance of reflux <span class="hlt">exchangers</span>. Four projects that show the value and effectiveness of reflux <span class="hlt">exchangers</span> are discussed below in more detail. The first example considers hydrogen recovery from demethanizer overheads; the second highlights a low energy process for NGL and LPG recovery from natural <span class="hlt">gas</span>. The third is a simple process for recovery of ethylene from fluid-catalytic cracker (FCC) offgas; and the fourth is a similar process for olefin recovery from dehydrogenation-reactor offgas.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28819793','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28819793"><span>The mechanisms underlying the production of discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> cycles in insects.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Matthews, Philip G D</p> <p>2018-03-01</p> <p>This review examines the control of <span class="hlt">gas</span> <span class="hlt">exchange</span> in insects, specifically examining what mechanisms could explain the emergence of discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> cycles (DGCs). DGCs are <span class="hlt">gas</span> <span class="hlt">exchange</span> patterns consisting of alternating breath-hold periods and bouts of <span class="hlt">gas</span> <span class="hlt">exchange</span>. While all insects are capable of displaying a continuous pattern of <span class="hlt">gas</span> <span class="hlt">exchange</span>, this episodic pattern is known to occur within only some groups of insects and then only sporadically or during certain phases of their life cycle. Investigations into DGCs have tended to emphasise the role of chemosensory thresholds in triggering spiracle opening as critical for producing these <span class="hlt">gas</span> <span class="hlt">exchange</span> patterns. However, a chemosensory basis for episodic breathing also requires an as-of-yet unidentified hysteresis between internal respiratory stimuli, chemoreceptors, and the spiracles. What has been less appreciated is the role that the insect's central nervous system (CNS) might play in generating episodic patterns of ventilation. The active ventilation displayed by many insects during DGCs suggests that this pattern could be the product of directed control by the CNS rather than arising passively as a result of self-sustaining oscillations in internal oxygen and carbon dioxide levels. This paper attempts to summarise what is currently known about insect <span class="hlt">gas</span> <span class="hlt">exchange</span> regulation, examining the location and control of ventilatory pattern generators in the CNS, the influence of chemoreceptor feedback in the form of O 2 and CO 2 /pH fluctuations in the haemolymph, and the role of state-dependent changes in CNS activity on ventilatory control. This information is placed in the context of what is currently known regarding the production of discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> patterns.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130011141','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130011141"><span>Prototype Vent <span class="hlt">Gas</span> Heat <span class="hlt">Exchanger</span> for Exploration EVA - Performance and Manufacturing Characteristics</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Quinn, Gregory J.; Strange, Jeremy; Jennings, Mallory</p> <p>2013-01-01</p> <p>NASA is developing new portable life support system (PLSS) technologies, which it is demonstrating in an unmanned ground based prototype unit called PLSS 2.0. One set of technologies within the PLSS provides suitable ventilation to an astronaut while on an EVA. A new component within the ventilation <span class="hlt">gas</span> loop is a liquid-to-<span class="hlt">gas</span> heat <span class="hlt">exchanger</span> to transfer excess heat from the <span class="hlt">gas</span> to the thermal control system s liquid coolant loop. A unique bench top prototype heat <span class="hlt">exchanger</span> was built and tested for use in PLSS 2.0. The heat <span class="hlt">exchanger</span> was designed as a counter-flow, compact plate fin type using stainless steel. Its design was based on previous compact heat <span class="hlt">exchangers</span> manufactured by United Technologies Aerospace Systems (UTAS), but was half the size of any previous heat <span class="hlt">exchanger</span> model and one third the size of previous liquid-to-<span class="hlt">gas</span> heat <span class="hlt">exchangers</span>. The prototype heat <span class="hlt">exchanger</span> was less than 40 cubic inches and weighed 2.57 lb. Performance of the heat <span class="hlt">exchanger</span> met the requirements and the model predictions. The water side and <span class="hlt">gas</span> side pressure drops were less 0.8 psid and 0.5 inches of water, respectively, and an effectiveness of 94% was measured at the nominal air side pressure of 4.1 psia.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985htcg.agarS....N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985htcg.agarS....N"><span>Heat <span class="hlt">exchangers</span> in regenerative <span class="hlt">gas</span> turbine cycles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nina, M. N. R.; Aguas, M. P. N.</p> <p>1985-09-01</p> <p>Advances in compact heat <span class="hlt">exchanger</span> design and fabrication together with fuel cost rises continuously improve the attractability of regenerative <span class="hlt">gas</span> turbine helicopter engines. In this study cycle parameters aiming at reduced specific fuel consumption and increased payload or mission range, have been optimized together with heat <span class="hlt">exchanger</span> type and size. The discussion is based on a typical mission for an attack helicopter in the 900 kw power class. A range of heat <span class="hlt">exchangers</span> is studied to define the most favorable geometry in terms of lower fuel consumption and minimum engine plus fuel weight. Heat <span class="hlt">exchanger</span> volume, frontal area ratio and pressure drop effect on cycle efficiency are considered.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li class="active"><span>2</span></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_2 --> <div id="page_3" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active"><span>3</span></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="41"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DFD.E4003J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DFD.E4003J"><span>Respiratory Mechanics and <span class="hlt">Gas</span> <span class="hlt">Exchange</span>: The Effect of Surfactants</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jbaily, Abdulrahman; Szeri, Andrew J.</p> <p>2017-11-01</p> <p>The purpose of the lung is to <span class="hlt">exchange</span> gases, primarily oxygen and carbon dioxide, between the atmosphere and the circulatory system. To enable this <span class="hlt">exchange</span>, the airways in the lungs terminate in some 300 million alveoli that provide adequate surface area for transport. During breathing, work must be done to stretch various tissues to accommodate a greater volume of <span class="hlt">gas</span>. Considerable work must also be done to expand the liquid lining (hypophase) that coats the interior surfaces of the alveoli. This is enabled by a surface active lipo-protein complex, known as pulmonary surfactant, that modifies the surface tension at the hypophase-air interface. Surfactants also serve as physical barriers that modify the rate of <span class="hlt">gas</span> transfer across interfaces. We develop a mathematical model to study the action of pulmonary surfactant and its determinative contributions to breathing. The model is used to explore the influence of surfactants on alveolar mechanics and on <span class="hlt">gas</span> <span class="hlt">exchange</span>: it relates the work of respiration at the level of the alveolus to the <span class="hlt">gas</span> <span class="hlt">exchange</span> rate through the changing influence of pulmonary surfactant over the breathing cycle. This work is motivated by a need to develop improved surfactant replacement therapies to treat serious medical conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010004231','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010004231"><span>BOREAS TE-10 Leaf <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hall, Forrest G. (Editor); Papagno, Andrea (Editor); Middleton, Elizabeth; Sullivan, Joseph</p> <p>2000-01-01</p> <p>The Boreal Ecosystem-Atmospheric Study (BOREAS) TE-10 (Terrestrial Ecology) team collected several data sets in support of its efforts to characterize and interpret information on the reflectance, transmittance, <span class="hlt">gas</span> <span class="hlt">exchange</span>, chlorophyll content, carbon content, hydrogen content, and nitrogen content of boreal vegetation. This data set contains measurements of assimilation, stomatal conductance, transpiration, internal CO2 concentration, and water use efficiency conducted in the Southern Study Area (SSA) during the growing seasons of 1994 and 1996 using a portable <span class="hlt">gas</span> <span class="hlt">exchange</span> system. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170009534','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170009534"><span><span class="hlt">Gas</span> Turbine Engine with Air/Fuel Heat <span class="hlt">Exchanger</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Krautheim, Michael Stephen (Inventor); Chouinard, Donald G. (Inventor); Donovan, Eric Sean (Inventor); Karam, Michael Abraham (Inventor); Vetters, Daniel Kent (Inventor)</p> <p>2017-01-01</p> <p>One embodiment of the present invention is a unique aircraft propulsion <span class="hlt">gas</span> turbine engine. Another embodiment is a unique <span class="hlt">gas</span> turbine engine. Another embodiment is a unique <span class="hlt">gas</span> turbine engine. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for <span class="hlt">gas</span> turbine engines with heat <span class="hlt">exchange</span> systems. Further embodiments, forms, features, aspects, benefits, and advantages of the present application will become apparent from the description and figures provided herewith.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18465177','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18465177"><span>Preoperative gender differences in pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> in morbidly obese subjects.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zavorsky, Gerald S; Christou, Nicolas V; Kim, Do Jun; Carli, Franco; Mayo, Nancy E</p> <p>2008-12-01</p> <p>Morbidly obese men may have poorer pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> compared to morbidly obese women (see Zavorsky et al., Chest 131:362-367, 2007). The purpose was to compare pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> in morbidly obese men and women at rest and throughout exercise. Twenty-five women (age=38+/-10 years, 164+/-7 cm, body mass index or BMI = 51+/-7 kg/m(2), peak oxygen consumption or VO(2peak)=2.0+/-0.4 l/min) and 17 men (age=43+/-9 years, 178+/-7 cm, BMI=50+/-10 kg/m(2), VO(2peak)=2.6+/-0.8 l/min) were recruited to perform a graded exercise test on a cycle ergometer with temperature-corrected arterial blood-<span class="hlt">gas</span> samples taken at rest and every minute of exercise, including peak exercise. At rest, women were 98% predicted for pulmonary diffusion compared to 88% predicted in men. At rest, women had better pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> compared to the men which was related to women having a lower waist-to-hip ratio (WHR; p<0.01). Only 20% of the subjects had an excessive alveolar-to-arterial oxygen partial pressure difference (>or=25 mmHg) at peak exercise, but 75% of the subjects showed inadequate compensatory hyperventilation at peak exercise (arterial carbon dioxide pressure >35 mmHg), and both were not different between genders. At rest, morbidly obese men have poorer pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> and pulmonary diffusion compared to morbidly obese women. The better <span class="hlt">gas</span> <span class="hlt">exchange</span> in women is related to the lower WHR in the women. During exercise, few subjects showed disturbances in pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> despite demonstrating poor compensatory hyperventilation at peak exercise.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120017344','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120017344"><span>Prototype Vent <span class="hlt">Gas</span> Heat <span class="hlt">Exchanger</span> for Exploration EVA - Performance and Manufacturing Characteristics</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jennings, Mallory; Quinn, Gregory; Strange, Jeremy</p> <p>2012-01-01</p> <p>NASA is developing new portable life support system (PLSS) technologies, which it is demonstrating in an unmanned ground based prototype unit called PLSS 2.0. One set of technologies within the PLSS provides suitable ventilation to an astronaut while on an EVA. A new component within the ventilation <span class="hlt">gas</span> loop is a liquid-to-<span class="hlt">gas</span> heat <span class="hlt">exchanger</span> to transfer excess heat from the <span class="hlt">gas</span> to the thermal control system's liquid coolant loop. A unique bench top prototype heat <span class="hlt">exchanger</span> was built and tested for use in PLSS 2.0. The heat <span class="hlt">exchanger</span> was designed as a counter-flow, compact plate fin type using stainless steel. Its design was based on previous compact heat <span class="hlt">exchangers</span> manufactured by United Technologies Aerospace Systems, but was half the size of any previous heat <span class="hlt">exchanger</span> model and one third the size of previous liquid-to-<span class="hlt">gas</span> heat <span class="hlt">exchangers</span>. The prototype heat <span class="hlt">exchanger</span> was less than 40 cubic inches and weighed 2.6 lb. The water side and <span class="hlt">gas</span> side pressure drops were 0.8 psid and 0.5 inches of water, respectively. Performance of the heat <span class="hlt">exchanger</span> at the nominal pressure of 4.1 psia was measured at 94%, while a <span class="hlt">gas</span> inlet pressure of 25 psia resulted in an effectiveness of 84%. These results compared well with the model, which was scaled for the small size. Modeling of certain phenomena that affect performance, such as flow distribution in the headers was particularly difficult due to the small size of the heat <span class="hlt">exchanger</span>. Data from the tests has confirmed the correction factors that were used in these parts of the model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850045092&hterms=water+gas+exchange&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dwater%2Bgas%2Bexchange','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850045092&hterms=water+gas+exchange&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dwater%2Bgas%2Bexchange"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span>-wind speed relation measured with sulfur hexafluoride on a lake</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wanninkhof, R.; Broecker, W. S.; Ledwell, J. R.</p> <p>1985-01-01</p> <p><span class="hlt">Gas-exchange</span> processes control the uptake and release of various gases in natural systems such as oceans, rivers, and lakes. Not much is known about the effect of wind speed on <span class="hlt">gas</span> <span class="hlt">exchange</span> in such systems. In the experiment described here, sulfur hexafluoride was dissolved in lake water, and the rate of escape of the <span class="hlt">gas</span> with wind speed (at wind speeds up to 6 meters per second) was determined over a 1-month period. A sharp change in the wind speed dependence of the <span class="hlt">gas-exchange</span> coefficient was found at wind speeds of about 2.4 meters per second, in agreement with the results of wind-tunnel studies. However the <span class="hlt">gas-exchange</span> coefficients at wind speeds above 3 meters per second were smaller than those observed in wind tunnels and are in agreement with earlier lake and ocean results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27209375','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27209375"><span><span class="hlt">Gas</span> <span class="hlt">Exchange</span> Models for a Flexible Insect Tracheal System.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Simelane, S M; Abelman, S; Duncan, F D</p> <p>2016-06-01</p> <p>In this paper two models for movement of respiratory gases in the insect trachea are presented. One model considers the tracheal system as a single flexible compartment while the other model considers the trachea as a single flexible compartment with <span class="hlt">gas</span> <span class="hlt">exchange</span>. This work represents an extension of Ben-Tal's work on compartmental <span class="hlt">gas</span> <span class="hlt">exchange</span> in human lungs and is applied to the insect tracheal system. The purpose of the work is to study nonlinear phenomena seen in the insect respiratory system. It is assumed that the flow inside the trachea is laminar, and that the air inside the chamber behaves as an ideal <span class="hlt">gas</span>. Further, with the isothermal assumption, the expressions for the tracheal partial pressures of oxygen and carbon dioxide, rate of volume change, and the rates of change of oxygen concentration and carbon dioxide concentration are derived. The effects of some flow parameters such as diffusion capacities, reaction rates and air concentrations on net flow are studied. Numerical simulations of the tracheal flow characteristics are performed. The models developed provide a mathematical framework to further investigate <span class="hlt">gas</span> <span class="hlt">exchange</span> in insects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/33600','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/33600"><span>Leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> of mature bottomland oak trees</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Rico M. Gazal; Mark E. Kubiske; Kristina F. Connor</p> <p>2009-01-01</p> <p>We determined how changes in environmental moisture affected leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> in Nuttall (Quercus texana Buckley), overcup (Q. lyrata Walt.), and dominant and codominant swamp chestnut (Q. michauxii Nutt.) oak trees in Mississippi and Louisiana. We used canopy access towers to measure leaf level <span class="hlt">gas</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880001086','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880001086"><span>The effect of wind and currents on <span class="hlt">gas</span> <span class="hlt">exchange</span> in an estuarine system</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Broecker, W. S.; Ledwell, J. R.; Bopp, R.</p> <p>1987-01-01</p> <p>The objectives were to develop a non-volatile tracer to use in <span class="hlt">gas</span> <span class="hlt">exchange</span> experiments in laterally unconfined systems and to study applications of deliberate tracers in limnology and oceanography. Progress was made on both fronts but work on the development of the non-volatile tracer proved to be more difficult and labor intensive that anticipated so no field experiments using non-volatile tracers was performed as yet. In the search for a suitable non-volatile tracer for an ocean scale <span class="hlt">gas</span> <span class="hlt">exchange</span> experiment a tracer was discovered which does not have the required sensitivity for a large scale experiment, but is very easy to analyze and will be well suited for smaller experiments such as <span class="hlt">gas</span> <span class="hlt">exchange</span> determinations on rivers and streams. Sulfur hexafluoride, SF6, was used successfully as a volatile tracer along with tritium as a non-volatile tracer to study <span class="hlt">gas</span> <span class="hlt">exchange</span> rates from a primary stream. This is the first <span class="hlt">gas</span> <span class="hlt">exchange</span> experiment in which <span class="hlt">gas</span> <span class="hlt">exchange</span> rates were determined on a head water stream where significant groundwater input occurs along the reach. In conjunction with SF6, Radon-222 measurements were performed on the groundwater and in the stream. The feasibility of using a combination of SF6 and radon is being studied to determine groundwater inputs and <span class="hlt">gas</span> <span class="hlt">exchange</span> of rates in streams with significant groundwater input without using a non-volatile tracer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006GeoRL..3315404D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006GeoRL..3315404D"><span>Circadian rhythms constrain leaf and canopy <span class="hlt">gas</span> <span class="hlt">exchange</span> in an Amazonian forest</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Doughty, Christopher E.; Goulden, Michael L.; Miller, Scott D.; da Rocha, Humberto R.</p> <p>2006-08-01</p> <p>We used a controlled-environment leaf <span class="hlt">gas-exchange</span> system and the micrometeorological technique eddy covariance to determine whether circadian rhythms constrain the rates of leaf and canopy <span class="hlt">gas</span> <span class="hlt">exchange</span> in an Amazonian forest over a day. When exposed to continuous and constant light for 20 to 48 hours leaves of eleven of seventeen species reduced their photosynthetic rates and closed their stomata during the normally dark period and resumed active <span class="hlt">gas</span> <span class="hlt">exchange</span> during the normally light period. Similarly, the rate of whole-forest CO2 uptake at a predetermined irradiance declined during the late afternoon and early morning and increased during the middle of the day. We attribute these cycles to circadian rhythms that are analogous to ones that have been reported for herbaceous plants in the laboratory. The importance of endogenous <span class="hlt">gas</span> <span class="hlt">exchange</span> rhythms presents a previously unrecognized challenge for efforts to both interpret and model land-atmosphere energy and mass <span class="hlt">exchange</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28406724','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28406724"><span>Fifty Years of Research in ARDS. <span class="hlt">Gas</span> <span class="hlt">Exchange</span> in Acute Respiratory Distress Syndrome.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Radermacher, Peter; Maggiore, Salvatore Maurizio; Mercat, Alain</p> <p>2017-10-15</p> <p>Acute respiratory distress syndrome (ARDS) is characterized by severe impairment of <span class="hlt">gas</span> <span class="hlt">exchange</span>. Hypoxemia is mainly due to intrapulmonary shunt, whereas increased alveolar dead space explains the alteration of CO 2 clearance. Assessment of the severity of <span class="hlt">gas</span> <span class="hlt">exchange</span> impairment is a requisite for the characterization of the syndrome and the evaluation of its severity. Confounding factors linked to hemodynamic status can greatly influence the relationship between the severity of lung injury and the degree of hypoxemia and/or the effects of ventilator settings on <span class="hlt">gas</span> <span class="hlt">exchange</span>. Apart from situations of rescue treatment, targeting optimal <span class="hlt">gas</span> <span class="hlt">exchange</span> in ARDS has become less of a priority compared with prevention of injury. A complex question for clinicians is to understand when improvement in oxygenation and alveolar ventilation is related to a lower degree or risk of injury for the lungs. In this regard, a full understanding of <span class="hlt">gas</span> <span class="hlt">exchange</span> mechanism in ARDS is imperative for individualized symptomatic support of patients with ARDS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22418709','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22418709"><span>Discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span>, water loss, and metabolism in Protaetia cretica (Cetoniinae, Scarabaeidae).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Matthews, Philip G D; White, Craig R</p> <p>2012-01-01</p> <p>Insects are at high risk of desiccation because of their small size, high surface-area-to-volume ratio, and air-filled tracheal system that ramifies throughout their bodies to transport O(2) and CO(2) to and from respiring cells. Although the tracheal system offers a high-conductance pathway for the movement of respiratory gases, it has the unintended consequence of allowing respiratory transpiration to the atmosphere. When resting, many species <span class="hlt">exchange</span> respiratory gases discontinuously, and an early hypothesis for the origin of these discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> cycles (DGCs) is that they serve to reduce respiratory water loss. In this study, we test this "hygric" hypothesis by comparing rates of CO(2) <span class="hlt">exchange</span> and water loss among flower beetles Protaetia cretica (Cetoniinae, Scarabaeidae) breathing either continuously or discontinuously. We show that, consistent with the expectations of the hygric hypothesis, rates of total water loss are higher during continuous <span class="hlt">gas</span> <span class="hlt">exchange</span> than during discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> and that the ratio of respiratory water loss to CO(2) <span class="hlt">exchange</span> is lower during discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span>. This conclusion is in agreement with other studies of beetles and cockroaches that also support the hygric hypothesis. However, this result does not exclude other adaptive hypotheses supported by work on ants and moth pupae. This ambiguity may arise because there are multiple independent evolutionary origins of DGCs and no single adaptive function underlying their genesis. Alternatively, the observed reduction in water loss during DGCs may be a side effect of a nonadaptive <span class="hlt">gas</span> <span class="hlt">exchange</span> pattern that is elicited during periods of inactivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25317652','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25317652"><span>Ventilation/Perfusion distribution <span class="hlt">abnormalities</span> in morbidly obese subjects before and after bariatric surgery.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rivas, Eva; Arismendi, Ebymar; Agustí, Alvar; Sanchez, Marcelo; Delgado, Salvadora; Gistau, Concepción; Wagner, Peter D; Rodriguez-Roisin, Roberto</p> <p>2015-04-01</p> <p>Obesity is a global and growing public health problem. Bariatric surgery (BS) is indicated in patients with morbid obesity. To our knowledge, the effects of morbid obesity and BS on ventilation/perfusion (V.a/Q.) ratio distributions using the multiple inert <span class="hlt">gas</span> elimination technique have never before been explored. We compared respiratory and inert <span class="hlt">gas</span> (V.a/Q. ratio distributions) pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span>, breathing both ambient air and 100% oxygen, in 19 morbidly obese women (BMI, 45 kg/m2), both before and 1 year after BS, and in eight normal-weight, never smoker, age-matched, healthy women. Before BS, morbidly obese individuals had reduced arterial Po2 (76 ± 2 mm Hg) and an increased alveolar-arterial Po2 difference (27 ± 2 mm Hg) caused by small amounts of shunt (4.3% ± 1.1% of cardiac output), along with <span class="hlt">abnormally</span> broadly unimodal blood flow dispersion (0.83 ± 0.06). During 100% oxygen breathing, shunt increased twofold in parallel with a reduction of blood flow to low V.a/Q. units, suggesting the development of reabsorption atelectasis without reversion of hypoxic pulmonary vasoconstriction. After BS, body weight was reduced significantly (BMI, 31 kg/m2), and pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> <span class="hlt">abnormalities</span> were decreased. Morbid obesity is associated with mild to moderate shunt and V.a/Q. imbalance. These <span class="hlt">abnormalities</span> are reduced after BS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880002876','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880002876"><span>Sunlight supply and <span class="hlt">gas</span> <span class="hlt">exchange</span> systems in microalgal bioreactor</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mori, K.; Ohya, H.; Matsumoto, K.; Furune, H.</p> <p>1987-01-01</p> <p>The bioreactor with sunlight supply system and <span class="hlt">gas</span> <span class="hlt">exchange</span> systems presented has proved feasible in ground tests and shows much promise for space use as a closed ecological life support system device. The chief conclusions concerning the specification of total system needed for a life support system for a man in a space station are the following: (1) Sunlight supply system - compactness and low electrical consumption; (2) Bioreactor system - high density and growth rate of chlorella; and (3) <span class="hlt">Gas</span> <span class="hlt">exchange</span> system - enough for O2 production and CO2 assimilation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1084027','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1084027"><span>Recovery of Water from Boiler Flue <span class="hlt">Gas</span> Using Condensing Heat <span class="hlt">Exchangers</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Levy, Edward; Bilirgen, Harun; DuPont, John</p> <p>2011-03-31</p> <p>Most of the water used in a thermoelectric power plant is used for cooling, and DOE has been focusing on possible techniques to reduce the amount of fresh water needed for cooling. DOE has also been placing emphasis on recovery of usable water from sources not generally considered, such as mine water, water produced from oil and <span class="hlt">gas</span> extraction, and water contained in boiler flue <span class="hlt">gas</span>. This report deals with development of condensing heat <span class="hlt">exchanger</span> technology for recovering moisture from flue <span class="hlt">gas</span> from coal-fired power plants. The report describes: • An expanded data base on water and acid condensation characteristicsmore » of condensing heat <span class="hlt">exchangers</span> in coal-fired units. This data base was generated by performing slip stream tests at a power plant with high sulfur bituminous coal and a wet FGD scrubber and at a power plant firing highmoisture, low rank coals. • Data on typical concentrations of HCl, HNO{sub 3} and H{sub 2}SO{sub 4} in low temperature condensed flue <span class="hlt">gas</span> moisture, and mercury capture efficiencies as functions of process conditions in power plant field tests. • Theoretical predictions for sulfuric acid concentrations on tube surfaces at temperatures above the water vapor dewpoint temperature and below the sulfuric acid dew point temperature. • Data on corrosion rates of candidate heat <span class="hlt">exchanger</span> tube materials for the different regions of the heat <span class="hlt">exchanger</span> system as functions of acid concentration and temperature. • Data on effectiveness of acid traps in reducing sulfuric acid concentrations in a heat <span class="hlt">exchanger</span> tube bundle. • Condensed flue <span class="hlt">gas</span> water treatment needs and costs. • Condensing heat <span class="hlt">exchanger</span> designs and installed capital costs for full-scale applications, both for installation immediately downstream of an ESP or baghouse and for installation downstream of a wet SO{sub 2} scrubber. • Results of cost-benefit studies of condensing heat <span class="hlt">exchangers</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1037725','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1037725"><span>Recovery of Water from Boiler Flue <span class="hlt">Gas</span> Using Condensing Heat <span class="hlt">Exchangers</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Edward Levy; Harun Bilirgen; John DuPoint</p> <p>2011-03-31</p> <p>Most of the water used in a thermoelectric power plant is used for cooling, and DOE has been focusing on possible techniques to reduce the amount of fresh water needed for cooling. DOE has also been placing emphasis on recovery of usable water from sources not generally considered, such as mine water, water produced from oil and <span class="hlt">gas</span> extraction, and water contained in boiler flue <span class="hlt">gas</span>. This report deals with development of condensing heat <span class="hlt">exchanger</span> technology for recovering moisture from flue <span class="hlt">gas</span> from coal-fired power plants. The report describes: (1) An expanded data base on water and acid condensation characteristicsmore » of condensing heat <span class="hlt">exchangers</span> in coal-fired units. This data base was generated by performing slip stream tests at a power plant with high sulfur bituminous coal and a wet FGD scrubber and at a power plant firing high-moisture, low rank coals. (2) Data on typical concentrations of HCl, HNO{sub 3} and H{sub 2}SO{sub 4} in low temperature condensed flue <span class="hlt">gas</span> moisture, and mercury capture efficiencies as functions of process conditions in power plant field tests. (3) Theoretical predictions for sulfuric acid concentrations on tube surfaces at temperatures above the water vapor dewpoint temperature and below the sulfuric acid dew point temperature. (4) Data on corrosion rates of candidate heat <span class="hlt">exchanger</span> tube materials for the different regions of the heat <span class="hlt">exchanger</span> system as functions of acid concentration and temperature. (5) Data on effectiveness of acid traps in reducing sulfuric acid concentrations in a heat <span class="hlt">exchanger</span> tube bundle. (6) Condensed flue <span class="hlt">gas</span> water treatment needs and costs. (7) Condensing heat <span class="hlt">exchanger</span> designs and installed capital costs for full-scale applications, both for installation immediately downstream of an ESP or baghouse and for installation downstream of a wet SO{sub 2} scrubber. (8) Results of cost-benefit studies of condensing heat <span class="hlt">exchangers</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/19485','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/19485"><span>A two-cell chamber for measuring <span class="hlt">gas</span> <span class="hlt">exchange</span> in tree seedlings</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Keith F. Jensen; Frederick W. Bender; Roberta G. Masters</p> <p>1973-01-01</p> <p>A two-celled chamber for measuring <span class="hlt">gas</span> <span class="hlt">exchange</span> in tree seedlings is described. Temperature is controlled within ± 0.5º C by means of a copper coil. The two cells are independent of one another, and one cell can be used as a preconditioning cell while <span class="hlt">gas</span> <span class="hlt">exchange</span> measurements are being made in the second cell.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NatCo...814012Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NatCo...814012Z"><span>Super-emitters in natural <span class="hlt">gas</span> infrastructure are caused by <span class="hlt">abnormal</span> process conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zavala-Araiza, Daniel; Alvarez, Ramón A.; Lyon, David R.; Allen, David T.; Marchese, Anthony J.; Zimmerle, Daniel J.; Hamburg, Steven P.</p> <p>2017-01-01</p> <p>Effectively mitigating methane emissions from the natural <span class="hlt">gas</span> supply chain requires addressing the disproportionate influence of high-emitting sources. Here we use a Monte Carlo simulation to aggregate methane emissions from all components on natural <span class="hlt">gas</span> production sites in the Barnett Shale production region (Texas). Our total emission estimates are two-thirds of those derived from independent site-based measurements. Although some high-emitting operations occur by design (condensate flashing and liquid unloadings), they occur more than an order of magnitude less frequently than required to explain the reported frequency at which high site-based emissions are observed. We conclude that the occurrence of <span class="hlt">abnormal</span> process conditions (for example, malfunctions upstream of the point of emissions; equipment issues) cause additional emissions that explain the gap between component-based and site-based emissions. Such <span class="hlt">abnormal</span> conditions can cause a substantial proportion of a site's <span class="hlt">gas</span> production to be emitted to the atmosphere and are the defining attribute of super-emitting sites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5026132','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5026132"><span>Lung Structure and the Intrinsic Challenges of <span class="hlt">Gas</span> <span class="hlt">Exchange</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hsia, Connie C.W.; Hyde, Dallas M.; Weibel, Ewald R.</p> <p>2016-01-01</p> <p>Structural and functional complexities of the mammalian lung evolved to meet a unique set of challenges, namely, the provision of efficient delivery of inspired air to all lung units within a confined thoracic space, to build a large <span class="hlt">gas</span> <span class="hlt">exchange</span> surface associated with minimal barrier thickness and a microvascular network to accommodate the entire right ventricular cardiac output while withstanding cyclic mechanical stresses that increase several folds from rest to exercise. Intricate regulatory mechanisms at every level ensure that the dynamic capacities of ventilation, perfusion, diffusion, and chemical binding to hemoglobin are commensurate with usual metabolic demands and periodic extreme needs for activity and survival. This article reviews the structural design of mammalian and human lung, its functional challenges, limitations, and potential for adaptation. We discuss (i) the evolutionary origin of alveolar lungs and its advantages and compromises, (ii) structural determinants of alveolar <span class="hlt">gas</span> <span class="hlt">exchange</span>, including architecture of conducting bronchovascular trees that converge in <span class="hlt">gas</span> <span class="hlt">exchange</span> units, (iii) the challenges of matching ventilation, perfusion, and diffusion and tissue-erythrocyte and thoracopulmonary interactions. The notion of erythrocytes as an integral component of the <span class="hlt">gas</span> <span class="hlt">exchanger</span> is emphasized. We further discuss the signals, sources, and limits of structural plasticity of the lung in alveolar hypoxia and following a loss of lung units, and the promise and caveats of interventions aimed at augmenting endogenous adaptive responses. Our objective is to understand how individual components are matched at multiple levels to optimize organ function in the face of physiological demands or pathological constraints. PMID:27065169</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27065169','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27065169"><span>Lung Structure and the Intrinsic Challenges of <span class="hlt">Gas</span> <span class="hlt">Exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hsia, Connie C W; Hyde, Dallas M; Weibel, Ewald R</p> <p>2016-03-15</p> <p>Structural and functional complexities of the mammalian lung evolved to meet a unique set of challenges, namely, the provision of efficient delivery of inspired air to all lung units within a confined thoracic space, to build a large <span class="hlt">gas</span> <span class="hlt">exchange</span> surface associated with minimal barrier thickness and a microvascular network to accommodate the entire right ventricular cardiac output while withstanding cyclic mechanical stresses that increase several folds from rest to exercise. Intricate regulatory mechanisms at every level ensure that the dynamic capacities of ventilation, perfusion, diffusion, and chemical binding to hemoglobin are commensurate with usual metabolic demands and periodic extreme needs for activity and survival. This article reviews the structural design of mammalian and human lung, its functional challenges, limitations, and potential for adaptation. We discuss (i) the evolutionary origin of alveolar lungs and its advantages and compromises, (ii) structural determinants of alveolar <span class="hlt">gas</span> <span class="hlt">exchange</span>, including architecture of conducting bronchovascular trees that converge in <span class="hlt">gas</span> <span class="hlt">exchange</span> units, (iii) the challenges of matching ventilation, perfusion, and diffusion and tissue-erythrocyte and thoracopulmonary interactions. The notion of erythrocytes as an integral component of the <span class="hlt">gas</span> <span class="hlt">exchanger</span> is emphasized. We further discuss the signals, sources, and limits of structural plasticity of the lung in alveolar hypoxia and following a loss of lung units, and the promise and caveats of interventions aimed at augmenting endogenous adaptive responses. Our objective is to understand how individual components are matched at multiple levels to optimize organ function in the face of physiological demands or pathological constraints. Copyright © 2016 John Wiley & Sons, Inc.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active"><span>3</span></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_3 --> <div id="page_4" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="61"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21917934','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21917934"><span>Air-<span class="hlt">gas</span> <span class="hlt">exchange</span> reevaluated: clinically important results of a computer simulation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shunmugam, Manoharan; Shunmugam, Sudhakaran; Williamson, Tom H; Laidlaw, D Alistair</p> <p>2011-10-21</p> <p>The primary aim of this study was to evaluate the efficiency of air-<span class="hlt">gas</span> <span class="hlt">exchange</span> techniques and the factors that influence the final concentration of an intraocular <span class="hlt">gas</span> tamponade. Parameters were varied to find the optimum method of performing an air-<span class="hlt">gas</span> <span class="hlt">exchange</span> in ideal circumstances. A computer model of the eye was designed using 3D software with fluid flow analysis capabilities. Factors such as angular distance between ports, <span class="hlt">gas</span> infusion gauge, exhaust vent gauge and depth were varied in the model. Flow rate and axial length were also modulated to simulate faster injections and more myopic eyes, respectively. The flush volume of <span class="hlt">gas</span> required to achieve a 97% intraocular <span class="hlt">gas</span> fraction concentration were compared. Modulating individual factors did not reveal any clinically significant difference in the angular distance between ports, exhaust vent size, and depth or rate of <span class="hlt">gas</span> injection. In combination, however, there was a 28% increase in air-<span class="hlt">gas</span> <span class="hlt">exchange</span> efficiency comparing the most efficient with the least efficient studied parameters in this model. The <span class="hlt">gas</span> flush volume required to achieve a 97% <span class="hlt">gas</span> fill also increased proportionately at a ratio of 5.5 to 6.2 times the volume of the eye. A 35-mL flush is adequate for eyes up to 25 mm in axial length; however, eyes longer than this would require a much greater flush volume, and surgeons should consider using two separate 50-mL <span class="hlt">gas</span> syringes to ensure optimal <span class="hlt">gas</span> concentration for eyes greater than 25 mm in axial length.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20046684','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20046684"><span>The efficacy of fluid-<span class="hlt">gas</span> <span class="hlt">exchange</span> for the treatment of postvitrectomy retinal detachment.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jang, Ji Hye; Kim, Yu Cheol; Kim, Kwang Soo</p> <p>2009-12-01</p> <p>This study was designed to evaluate the efficacy of fluid-<span class="hlt">gas</span> <span class="hlt">exchange</span> for the treatment of postvitrectomy retinal detachment. We retrospectively reviewed the records of 33 consecutive patients (35 eyes) who underwent fluid-<span class="hlt">gas</span> <span class="hlt">exchange</span> treatment for postvitrectomy retinal detachment using the two-needle pars plana approach technique. The retinal reattachment rate was 80.0% after complete intravitreal <span class="hlt">gas</span> disappearance following the fluid-<span class="hlt">gas</span> <span class="hlt">exchange</span>; the overall success rate was 65.7%. Visual acuity was improved or stable in 80.0% of cases; a two-line or greater vision improvement or a best-corrected visual acuity of 0.4 or better occurred in 62.9% of cases. The success rates for superior retinal detachments and posterior pole retinal detachments were 76.5% and 85.7%, respectively. Fluid-<span class="hlt">gas</span> <span class="hlt">exchange</span> represents a simple and cost-effective alternative outpatient procedure for retinal reattachment without reoperation for the treatment of superior and posterior pole retinal detachments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27424100','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27424100"><span>In vivo effects of Aphanizomenon flos-aquae DC-1 aphantoxins on <span class="hlt">gas</span> <span class="hlt">exchange</span> and ion equilibrium in the zebrafish gill.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Delu; Liu, Siyi; Zhang, Jing; Zhang, Jian Kong; Hu, Chunxiang; Liu, Yongding</p> <p>2016-08-01</p> <p>Aphantoxins, neurotoxins or paralytic shellfish poisons (PSPs) generated by Aphanizomenon flos-aquae, are a threat to environmental safety and human health in eutrophic waters worldwide. The molecular mechanisms of neurotoxin function have been studied; however, the effects of these neurotoxins on oxidative stress, ion transport, <span class="hlt">gas</span> <span class="hlt">exchange</span>, and branchial ultrastructure in fish gills are not fully understood. Aphantoxins extracted from A. flos-aquae DC-1 were detected by high-performance liquid chromatography. The major ingredients were gonyautoxins 1 and 5 and neosaxitoxin, which comprised 34.04%, 21.28%, and 12.77% of the total, respectively. Zebrafish (Danio rerio) were administered A. flos-aquae DC-1 aphantoxins at 5.3 or 7.61μg saxitoxin equivalents (eq)/kg (low and high doses, respectively) by intraperitoneal injection. The activities of Na(+)-K(+)-ATPase (NKA), carbonic anhydrase (CA), and lactate dehydrogenase (LDH), ultrastructural alterations in chloride and epithelial cells, and reactive oxygen species (ROS) and total antioxidative capacity (T-AOC) were investigated in the gills during the first 24h after exposure. Aphantoxins significantly increased the level of ROS and decreased the T-AOC in zebrafish gills from 3 to 12h post-exposure, suggesting an induction of oxidative stress and inhibition of antioxidant capacity. Reduced activities of NKA and CA demonstrated <span class="hlt">abnormal</span> ion transport and <span class="hlt">gas</span> <span class="hlt">exchange</span> in the gills of aphantoxin-treated fish. Toxin administration also resulted in increased LDH activity and ultrastructural alterations in chloride and epithelial cells, suggesting a disruption of function and structure in zebrafish gills. The observed <span class="hlt">abnormalities</span> in zebrafish gills occurred in a time- and dose-dependent manner. These findings demonstrate that aphantoxins or PSPs may inhibit ion transport and <span class="hlt">gas</span> <span class="hlt">exchange</span>, increase LDH activity, and result in ultrastructural damage to the gills through elevations in oxidative stress and reduced</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920056264&hterms=gas+natural&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dgas%2Bnatural','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920056264&hterms=gas+natural&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dgas%2Bnatural"><span>Relationship between wind speed and <span class="hlt">gas</span> <span class="hlt">exchange</span> over the ocean</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wanninkhof, Rik</p> <p>1992-01-01</p> <p>A quadratic dependence of <span class="hlt">gas</span> <span class="hlt">exchange</span> on wind speed is employed to analyze the relationship between <span class="hlt">gas</span> transfer and wind speed with particular emphasizing variable and/or low wind speeds. The quadratic dependence is fit through <span class="hlt">gas</span>-transfer velocities over the ocean determined by methods based on the natural C-14 disequilibrium and the bomb C-14 inventory. The variation in the CO2 levels is related to these mechanisms, but the results show that other causes play significant roles. A weaker dependence of <span class="hlt">gas</span> transfer on wind is suggested for steady winds, and long-term averaged winds demonstrate a stronger dependence in the present model. The chemical enhancement of CO2 <span class="hlt">exchange</span> is also shown to play a role by increasing CO2 fluxes at low wind speeds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JASMS..28..971H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JASMS..28..971H"><span>Regio-Selective Intramolecular Hydrogen/Deuterium <span class="hlt">Exchange</span> in <span class="hlt">Gas</span>-Phase Electron Transfer Dissociation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hamuro, Yoshitomo</p> <p>2017-05-01</p> <p>Protein backbone amide hydrogen/deuterium <span class="hlt">exchange</span> mass spectrometry (HDX-MS) typically utilizes enzymatic digestion after the <span class="hlt">exchange</span> reaction and before MS analysis to improve data resolution. <span class="hlt">Gas</span>-phase fragmentation of a peptic fragment prior to MS analysis is a promising technique to further increase the resolution. The biggest technical challenge for this method is elimination of intramolecular hydrogen/deuterium <span class="hlt">exchange</span> (scrambling) in the <span class="hlt">gas</span> phase. The scrambling obscures the location of deuterium. Jørgensen's group pioneered a method to minimize the scrambling in <span class="hlt">gas</span>-phase electron capture/transfer dissociation. Despite active investigation, the mechanism of hydrogen scrambling is not well-understood. The difficulty stems from the fact that the degree of hydrogen scrambling depends on instruments, various parameters of mass analysis, and peptide analyzed. In most hydrogen scrambling investigations, the hydrogen scrambling is measured by the percentage of scrambling in a whole molecule. This paper demonstrates that the degree of intramolecular hydrogen/deuterium <span class="hlt">exchange</span> depends on the nature of <span class="hlt">exchangeable</span> hydrogen sites. The deuterium on Tyr amide of neurotensin (9-13), Arg-Pro-Tyr-Ile-Leu, migrated significantly faster than that on Ile or Leu amides, indicating the loss of deuterium from the original sites is not mere randomization of hydrogen and deuterium but more site-specific phenomena. This more precise approach may help understand the mechanism of intramolecular hydrogen <span class="hlt">exchange</span> and provide higher confidence for the parameter optimization to eliminate intramolecular hydrogen/deuterium <span class="hlt">exchange</span> during <span class="hlt">gas</span>-phase fragmentation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28194737','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28194737"><span>Regio-Selective Intramolecular Hydrogen/Deuterium <span class="hlt">Exchange</span> in <span class="hlt">Gas</span>-Phase Electron Transfer Dissociation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hamuro, Yoshitomo</p> <p>2017-05-01</p> <p>Protein backbone amide hydrogen/deuterium <span class="hlt">exchange</span> mass spectrometry (HDX-MS) typically utilizes enzymatic digestion after the <span class="hlt">exchange</span> reaction and before MS analysis to improve data resolution. <span class="hlt">Gas</span>-phase fragmentation of a peptic fragment prior to MS analysis is a promising technique to further increase the resolution. The biggest technical challenge for this method is elimination of intramolecular hydrogen/deuterium <span class="hlt">exchange</span> (scrambling) in the <span class="hlt">gas</span> phase. The scrambling obscures the location of deuterium. Jørgensen's group pioneered a method to minimize the scrambling in <span class="hlt">gas</span>-phase electron capture/transfer dissociation. Despite active investigation, the mechanism of hydrogen scrambling is not well-understood. The difficulty stems from the fact that the degree of hydrogen scrambling depends on instruments, various parameters of mass analysis, and peptide analyzed. In most hydrogen scrambling investigations, the hydrogen scrambling is measured by the percentage of scrambling in a whole molecule. This paper demonstrates that the degree of intramolecular hydrogen/deuterium <span class="hlt">exchange</span> depends on the nature of <span class="hlt">exchangeable</span> hydrogen sites. The deuterium on Tyr amide of neurotensin (9-13), Arg-Pro-Tyr-Ile-Leu, migrated significantly faster than that on Ile or Leu amides, indicating the loss of deuterium from the original sites is not mere randomization of hydrogen and deuterium but more site-specific phenomena. This more precise approach may help understand the mechanism of intramolecular hydrogen <span class="hlt">exchange</span> and provide higher confidence for the parameter optimization to eliminate intramolecular hydrogen/deuterium <span class="hlt">exchange</span> during <span class="hlt">gas</span>-phase fragmentation. Graphical Abstract ᅟ.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1611343P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1611343P"><span>Surfactant control of air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> across contrasting biogeochemical regimes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pereira, Ryan; Schneider-Zapp, Klaus; Upstill-Goddard, Robert</p> <p>2014-05-01</p> <p>Air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> is important to the global partitioning of CO2.<span class="hlt">Exchange</span> fluxes are products of an air-sea <span class="hlt">gas</span> concentration difference, ΔC, and a <span class="hlt">gas</span> transfer velocity, kw. The latter is controlled by the rate of turbulent diffusion at the air-sea interface but it cannot be directly measured and has a high uncertainty that is now considered one of the greatest challenges to quantifying net global air-sea CO2 <span class="hlt">exchange</span> ...(Takahashi et al., 2009). One important control on kw is exerted by sea surface surfactants that arise both naturally from biological processes and through anthropogenic activity. They influence <span class="hlt">gas</span> <span class="hlt">exchange</span> in two fundamental ways: as a monolayer physical barrier and through modifying sea surface hydrodynamics and hence turbulent energy transfer. These effects have been demonstrated in the laboratory with artificial surfactants ...(Bock et al., 1999; Goldman et al., 1988) and through purposeful surfactant releases in coastal waters .(.).........().(Brockmann et al., 1982) and in the open ocean (Salter et al., 2011). Suppression of kwin these field experiments was ~5-55%. While changes in both total surfactant concentration and the composition of the natural surfactant pool might be expected to impact kw, the required in-situ studies are lacking. New data collected from the coastal North Sea in 2012-2013 shows significant spatio-temporal variability in the surfactant activity of organic matter within the sea surface microlayer that ranges from 0.07-0.94 mg/L T-X-100 (AC voltammetry). The surfactant activities show a strong winter/summer seasonal bias and general decrease in concentration with increasing distance from the coastline possibly associated with changing terrestrial vs. phytoplankton sources. <span class="hlt">Gas</span> <span class="hlt">exchange</span> experiments of this seawater using a novel laboratory tank and <span class="hlt">gas</span> tracers (CH4 and SF6) demonstrate a 12-45% reduction in kw compared to surfactant-free water. Seasonally there is higher <span class="hlt">gas</span> <span class="hlt">exchange</span> suppression in the summer</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014OcSci..10..587S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014OcSci..10..587S"><span>An automated <span class="hlt">gas</span> <span class="hlt">exchange</span> tank for determining <span class="hlt">gas</span> transfer velocities in natural seawater samples</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schneider-Zapp, K.; Salter, M. E.; Upstill-Goddard, R. C.</p> <p>2014-07-01</p> <p>In order to advance understanding of the role of seawater surfactants in the air-sea <span class="hlt">exchange</span> of climatically active trace gases via suppression of the <span class="hlt">gas</span> transfer velocity (kw), we constructed a fully automated, closed air-water <span class="hlt">gas</span> <span class="hlt">exchange</span> tank and coupled analytical system. The system allows water-side turbulence in the tank to be precisely controlled with an electronically operated baffle. Two coupled <span class="hlt">gas</span> chromatographs and an integral equilibrator, connected to the tank in a continuous <span class="hlt">gas</span>-tight system, allow temporal changes in the partial pressures of SF6, CH4 and N2O to be measured simultaneously in the tank water and headspace at multiple turbulence settings, during a typical experimental run of 3.25 h. PC software developed by the authors controls all operations and data acquisition, enabling the optimisation of experimental conditions with high reproducibility. The use of three gases allows three independent estimates of kw for each turbulence setting; these values are subsequently normalised to a constant Schmidt number for direct comparison. The normalised kw estimates show close agreement. Repeated experiments with Milli-Q water demonstrate a typical measurement accuracy of 4% for kw. Experiments with natural seawater show that the system clearly resolves the effects on kw of spatial and temporal trends in natural surfactant activity. The system is an effective tool with which to probe the relationships between kw, surfactant activity and biogeochemical indices of primary productivity, and should assist in providing valuable new insights into the air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014OcScD..11..693S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014OcScD..11..693S"><span>An automated <span class="hlt">gas</span> <span class="hlt">exchange</span> tank for determining <span class="hlt">gas</span> transfer velocities in natural seawater samples</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schneider-Zapp, K.; Salter, M. E.; Upstill-Goddard, R. C.</p> <p>2014-02-01</p> <p>In order to advance understanding of the role of seawater surfactants in the air-sea <span class="hlt">exchange</span> of climatically active trace gases via suppression of the <span class="hlt">gas</span> transfer velocity (kw), we constructed a fully automated, closed air-water <span class="hlt">gas</span> <span class="hlt">exchange</span> tank and coupled analytical system. The system allows water-side turbulence in the tank to be precisely controlled with an electronically operated baffle. Two coupled <span class="hlt">gas</span> chromatographs and an integral equilibrator, connected to the tank in a continuous <span class="hlt">gas</span>-tight system, allow temporal changes in the partial pressures of SF6, CH4 and N2O to be measured simultaneously in the tank water and headspace at multiple turbulence settings, during a typical experimental run of 3.25 h. PC software developed by the authors controls all operations and data acquisition, enabling the optimisation of experimental conditions with high reproducibility. The use of three gases allows three independent estimates of kw for each turbulence setting; these values are subsequently normalised to a constant Schmidt number for direct comparison. The normalised kw estimates show close agreement. Repeated experiments with MilliQ water demonstrate a typical measurement accuracy of 4% for kw. Experiments with natural seawater show that the system clearly resolves the effects on kw of spatial and temporal trends in natural surfactant activity. The system is an effective tool with which to probe the relationships between kw, surfactant activity and biogeochemical indices of primary productivity, and should assist in providing valuable new insights into the air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2917398','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2917398"><span>Childhood physical <span class="hlt">abnormalities</span> following paternal exposure to sulfur mustard <span class="hlt">gas</span> in Iran: a case-control study</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2010-01-01</p> <p>Background Mustard <span class="hlt">gas</span>, a known chemical weapon, was used during the Iran-Iraq war of 1980-1988. We aimed to determine if exposure to mustard <span class="hlt">gas</span> among men was significantly associated with <span class="hlt">abnormalities</span> and disorders among progenies. Methods Using a case-control design, we identified all progenies of Sardasht men (exposed group, n = 498), who were born at least nine months after the exposure, compared to age-matched controls in Rabat, a nearby city (non-exposed group, n = 689). We conducted a thorough medical history, physical examination, and appropriate paraclinical studies to detect any physical <span class="hlt">abnormality</span> and/or disorder. Given the presence of correlated data, we applied Generalized Estimating Equation (GEE) multivariable models to determine associations. Results The overall frequency of detected physical <span class="hlt">abnormalities</span> and disorders was significantly higher in the exposed group (19% vs. 11%, Odds Ratio [OR] 1.93, 95% Confidence Interval [CI], 1.37-2.72, P = 0.0002). This was consistent across sexes. Congenital anomalies (OR 3.54, 95% CI, 1.58-7.93, P = 0.002) and asthma (OR, 3.12, 95% CI, 1.43-6.80, P = 0.004) were most commonly associated with exposure. No single <span class="hlt">abnormality</span> was associated with paternal exposure to mustard <span class="hlt">gas</span>. Conclusion Our study demonstrates a generational effect of exposure to mustard <span class="hlt">gas</span>. The lasting effects of mustard <span class="hlt">gas</span> exposure in parents effects fertility and may impact child health and development in the long-term. PMID:20630096</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27835767','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27835767"><span>Improving respiration measurements with <span class="hlt">gas</span> <span class="hlt">exchange</span> analyzers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Montero, R; Ribas-Carbó, M; Del Saz, N F; El Aou-Ouad, H; Berry, J A; Flexas, J; Bota, J</p> <p>2016-12-01</p> <p>Dark respiration measurements with open-flow <span class="hlt">gas</span> <span class="hlt">exchange</span> analyzers are often questioned for their low accuracy as their low values often reach the precision limit of the instrument. Respiration was measured in five species, two hypostomatous (Vitis Vinifera L. and Acanthus mollis) and three amphistomatous, one with similar amount of stomata in both sides (Eucalyptus citriodora) and two with different stomata density (Brassica oleracea and Vicia faba). CO 2 differential (ΔCO 2 ) increased two-fold with no change in apparent R d , when the two leaves with higher stomatal density faced outside. These results showed a clear effect of the position of stomata on ΔCO 2 . Therefore, it can be concluded that leaf position is important to guarantee the improvement of respiration measurements increasing ΔCO 2 without affecting the respiration results by leaf or mass units. This method will help to increase the accuracy of leaf respiration measurements using <span class="hlt">gas</span> <span class="hlt">exchange</span> analyzers. Copyright © 2016 Elsevier GmbH. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRC..123.2293B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRC..123.2293B"><span>Wave Attenuation and <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Velocity in Marginal Sea Ice Zone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bigdeli, A.; Hara, T.; Loose, B.; Nguyen, A. T.</p> <p>2018-03-01</p> <p>The <span class="hlt">gas</span> transfer velocity in marginal sea ice zones exerts a strong control on the input of anthropogenic gases into the ocean interior. In this study, a sea state-dependent <span class="hlt">gas</span> <span class="hlt">exchange</span> parametric model is developed based on the turbulent kinetic energy dissipation rate. The model is tuned to match the conventional <span class="hlt">gas</span> <span class="hlt">exchange</span> parametrization in fetch-unlimited, fully developed seas. Next, fetch limitation is introduced in the model and results are compared to fetch limited experiments in lakes, showing that the model captures the effects of finite fetch on <span class="hlt">gas</span> <span class="hlt">exchange</span> with good fidelity. Having validated the results in fetch limited waters such as lakes, the model is next applied in sea ice zones using an empirical relation between the sea ice cover and the effective fetch, while accounting for the sea ice motion effect that is unique to sea ice zones. The model results compare favorably with the available field measurements. Applying this parametric model to a regional Arctic numerical model, it is shown that, under the present conditions, <span class="hlt">gas</span> flux into the Arctic Ocean may be overestimated by 10% if a conventional parameterization is used.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21941230','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21941230"><span>Sildenafil citrate, bronchopulmonary dysplasia and disordered pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span>: any benefits?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nyp, M; Sandritter, T; Poppinga, N; Simon, C; Truog, W E</p> <p>2012-01-01</p> <p>The objective of this study is to determine the effects that sildenafil citrate has on <span class="hlt">gas</span> <span class="hlt">exchange</span> in infants with bronchopulmonary dysplasia (BPD)-associated pulmonary hypertension (PH). A retrospective review was performed from 2005 to 2009. Infants treated with sildenafil citrate for greater than 48  h were included. Standard patient data was collected, including echocardiogram, inspired oxygen and systemic blood pressure, before and during administration of sildenafil citrate. Sildenafil citrate was used in 21 preterm infants with BPD-associated PH. A significant reduction in estimated right ventricular peak systolic pressure was seen after initiation of sildenafil citrate, with the majority of infants showing no improvement in <span class="hlt">gas</span> <span class="hlt">exchange</span> at 48  h of treatment. Four infants died during treatment. Sildenafil citrate reduced estimated pulmonary artery pressures, but this reduction was not reflected in improved <span class="hlt">gas</span> <span class="hlt">exchange</span> within the first 48  h.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16545998','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16545998"><span>Foliar trichomes, boundary layers, and <span class="hlt">gas</span> <span class="hlt">exchange</span> in 12 species of epiphytic Tillandsia (Bromeliaceae).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Benz, Brett W; Martin, Craig E</p> <p>2006-04-01</p> <p>We examined the relationships between H2O and CO2 <span class="hlt">gas</span> <span class="hlt">exchange</span> parameters and leaf trichome cover in 12 species of Tillandsia that exhibit a wide range in trichome size and trichome cover. Previous investigations have hypothesized that trichomes function to enhance boundary layers around Tillandsioid leaves thereby buffering the evaporative demand of the atmosphere and retarding transpirational water loss. Data presented herein suggest that trichome-enhanced boundary layers have negligible effects on Tillandsia <span class="hlt">gas</span> <span class="hlt">exchange</span>, as indicated by the lack of statistically significant relationships in regression analyses of <span class="hlt">gas</span> <span class="hlt">exchange</span> parameters and trichome cover. We calculated trichome and leaf boundary layer components, and their associated effects on H2O and CO2 <span class="hlt">gas</span> <span class="hlt">exchange</span>. The results further indicate trichome-enhanced boundary layers do not significantly reduce transpirational water loss. We conclude that although the trichomes undoubtedly increase the thickness of the boundary layer, the increase due to Tillandsioid trichomes is inconsequential in terms of whole leaf boundary layers, and any associated reduction in transpirational water loss is also negligible within the whole plant <span class="hlt">gas</span> <span class="hlt">exchange</span> pathway.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26868055','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26868055"><span>A meta-analysis of leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and water status responses to drought.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yan, Weiming; Zhong, Yangquanwei; Shangguan, Zhouping</p> <p>2016-02-12</p> <p>Drought is considered to be one of the most devastating natural hazards, and it is predicted to become increasingly frequent and severe in the future. Understanding the plant <span class="hlt">gas</span> <span class="hlt">exchange</span> and water status response to drought is very important with regard to future climate change. We conducted a meta-analysis based on studies of plants worldwide and aimed to determine the changes in <span class="hlt">gas</span> <span class="hlt">exchange</span> and water status under different drought intensities (mild, moderate and severe), different photosynthetic pathways (C3 and C4) and growth forms (herbs, shrubs, trees and lianas). Our results were as follows: 1) drought negatively impacted <span class="hlt">gas</span> <span class="hlt">exchange</span> and water status, and stomatal conductance (gs) decreased more than other physiological traits and declined to the greatest extent in shrubs and C3 plants. Furthermore, C4 plants had an advantage compared to C3 plants under the same drought conditions. 2) The decrease in gs mainly reduced the transpiration rate (Tr), and gs could explain 55% of the decrease in the photosynthesis (A) and 74% of the decline in Tr. 3). Finally, <span class="hlt">gas</span> <span class="hlt">exchange</span> showed a close relationship with the leaf water status. Our study provides comprehensive information about the changes in plant <span class="hlt">gas</span> <span class="hlt">exchange</span> and water status under drought.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4751433','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4751433"><span>A meta-analysis of leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and water status responses to drought</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Yan, Weiming; Zhong, Yangquanwei; Shangguan, Zhouping</p> <p>2016-01-01</p> <p>Drought is considered to be one of the most devastating natural hazards, and it is predicted to become increasingly frequent and severe in the future. Understanding the plant <span class="hlt">gas</span> <span class="hlt">exchange</span> and water status response to drought is very important with regard to future climate change. We conducted a meta-analysis based on studies of plants worldwide and aimed to determine the changes in <span class="hlt">gas</span> <span class="hlt">exchange</span> and water status under different drought intensities (mild, moderate and severe), different photosynthetic pathways (C3 and C4) and growth forms (herbs, shrubs, trees and lianas). Our results were as follows: 1) drought negatively impacted <span class="hlt">gas</span> <span class="hlt">exchange</span> and water status, and stomatal conductance (gs) decreased more than other physiological traits and declined to the greatest extent in shrubs and C3 plants. Furthermore, C4 plants had an advantage compared to C3 plants under the same drought conditions. 2) The decrease in gs mainly reduced the transpiration rate (Tr), and gs could explain 55% of the decrease in the photosynthesis (A) and 74% of the decline in Tr. 3). Finally, <span class="hlt">gas</span> <span class="hlt">exchange</span> showed a close relationship with the leaf water status. Our study provides comprehensive information about the changes in plant <span class="hlt">gas</span> <span class="hlt">exchange</span> and water status under drought. PMID:26868055</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11967744','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11967744"><span>[Phylogeny of <span class="hlt">gas</span> <span class="hlt">exchange</span> systems].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jürgens, K D; Gros, G</p> <p>2002-04-01</p> <p>Several systems of <span class="hlt">gas</span> transport have developed during evolution, all of which are able to sufficiently supply oxygen to the tissues and eliminate the CO2 produced by the metabolism, in spite of great distances between the environment and the individual cells of the tissues. Almost all these systems utilize a combination of convection and diffusion steps. Convection achieves an efficient transport of <span class="hlt">gas</span> over large distances, but requires energy and cannot occur across tissue barriers. Diffusion, on the other hand, achieves <span class="hlt">gas</span> transport across barriers, but requires optimization of diffusion paths and diffusion areas. When two convectional <span class="hlt">gas</span> flows are linked via a diffusional barrier (<span class="hlt">gas</span>/fluid in the case of the avian lung, fluid/fluid in the case of gills), the directions in which the respective convectional movements pass each other are important determinants of <span class="hlt">gas</span> <span class="hlt">exchange</span> efficiency (concurrent, countercurrent and cross-current systems). The tracheal respiration found in insects has the advantage of circumventing the convective <span class="hlt">gas</span> transport step in the blood, thereby avoiding the high energy expenditure of circulatory systems. This is made possible by a system of tracheae, ending in tracheoles, that reaches from the body surface to every cell within the body. The last step of <span class="hlt">gas</span> transfer in these animals occurs by diffusion from the tracheoles ("air capillaries") to the mitochondria of cells. The disadvantage is that the tracheal system occupies a substantial fraction of body volume and that, due to limited mechanical stability of tracheal walls, this system would not be able to operate under conditions of high hydrostatic pressures, i. e. in large animals. Respiration in an "open" system, i. e. direct exposure of the diffusional barrier to the environmental air, eliminates the problem of bringing the oxygen to the barrier by convection, as is necessary in the avian and mammalian lung, in the insects' tracheal system and in the gills. An open system is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10926641','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10926641"><span>Response-time enhancement of a clinical <span class="hlt">gas</span> analyzer facilitates measurement of breath-by-breath <span class="hlt">gas</span> <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Farmery, A D; Hahn, C E</p> <p>2000-08-01</p> <p>Tidal ventilation <span class="hlt">gas-exchange</span> models in respiratory physiology and medicine not only require solution of mass balance equations breath-by-breath but also may require within-breath measurements, which are instantaneous functions of time. This demands a degree of temporal resolution and fidelity of integration of <span class="hlt">gas</span> flow and concentration signals that cannot be provided by most clinical <span class="hlt">gas</span> analyzers because of their slow response times. We have characterized the step responses of the Datex Ultima (Datex Instrumentation, Helsinki, Finland) <span class="hlt">gas</span> analyzer to oxygen, carbon dioxide, and nitrous oxide in terms of a Gompertz four-parameter sigmoidal function. By inversion of this function, we were able to reduce the rise times for all these gases almost fivefold, and, by its application to real on-line respiratory <span class="hlt">gas</span> signals, it is possible to achieve a performance comparable to the fastest mass spectrometers. With the use of this technique, measurements required for non-steady-state and tidal <span class="hlt">gas-exchange</span> models can be made easily and reliably in the clinical setting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.C31D..01L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.C31D..01L"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span> in the ice zone: the role of small waves and big animals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Loose, B.; Takahashi, A.; Bigdeli, A.</p> <p>2016-12-01</p> <p>The balance of air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> and net biological carbon fixation determine the transport and transformation of carbon dioxide and methane in the ocean. Air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> is mostly driven by upper ocean physics, but biology can also play a role. In the open ocean, <span class="hlt">gas</span> <span class="hlt">exchange</span> increases proportionate to the square of wind speed. When sea ice is present, this dependence breaks down in part because breaking waves and air bubble entrainment are damped out by interactions between sea ice and the wave field. At the same time, sea ice motions, formation, melt, and even sea ice-associated organisms can act to introduce turbulence and air bubbles into the upper ocean, thereby enhancing air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span>. We take advantage of the knowledge advances of upper ocean physics including bubble dynamics to formulate a model for air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> in the sea ice zone. Here, we use the model to examine the role of small-scale waves and diving animals that trap air for insulation, including penguins, seals and polar bears. We compare these processes to existing parameterizations of wave and bubble dynamics in the open ocean, to observe how sea ice both mitigates and locally enhances air-sea <span class="hlt">gas</span> transfer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23821716','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23821716"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span> patterns and water loss rates in the Table Mountain cockroach, Aptera fusca (Blattodea: Blaberidae).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Groenewald, Berlizé; Bazelet, Corinna S; Potter, C Paige; Terblanche, John S</p> <p>2013-10-15</p> <p>The importance of metabolic rate and/or spiracle modulation for saving respiratory water is contentious. One major explanation for <span class="hlt">gas</span> <span class="hlt">exchange</span> pattern variation in terrestrial insects is to effect a respiratory water loss (RWL) saving. To test this, we measured the rates of CO2 and H2O release ( and , respectively) in a previously unstudied, mesic cockroach, Aptera fusca, and compared <span class="hlt">gas</span> <span class="hlt">exchange</span> and water loss parameters among the major <span class="hlt">gas</span> <span class="hlt">exchange</span> patterns (continuous, cyclic, discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span>) at a range of temperatures. Mean , and per unit did not differ among the <span class="hlt">gas</span> <span class="hlt">exchange</span> patterns at all temperatures (P>0.09). There was no significant association between temperature and <span class="hlt">gas</span> <span class="hlt">exchange</span> pattern type (P=0.63). Percentage of RWL (relative to total water loss) was typically low (9.79±1.84%) and did not differ significantly among <span class="hlt">gas</span> <span class="hlt">exchange</span> patterns at 15°C (P=0.26). The method of estimation had a large impact on the percentage of RWL, and of the three techniques investigated (traditional, regression and hyperoxic switch), the traditional method generally performed best. In many respects, A. fusca has typical <span class="hlt">gas</span> <span class="hlt">exchange</span> for what might be expected from other insects studied to date (e.g. , , RWL and cuticular water loss). However, we found for A. fusca that expressed as a function of metabolic rate was significantly higher than the expected consensus relationship for insects, suggesting it is under considerable pressure to save water. Despite this, we found no consistent evidence supporting the conclusion that transitions in pattern type yield reductions in RWL in this mesic cockroach.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_4 --> <div id="page_5" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="81"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ThEng..64..680B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ThEng..64..680B"><span>Investigation and optimization of the depth of flue <span class="hlt">gas</span> heat recovery in surface heat <span class="hlt">exchangers</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bespalov, V. V.; Bespalov, V. I.; Melnikov, D. V.</p> <p>2017-09-01</p> <p>Economic issues associated with designing deep flue <span class="hlt">gas</span> heat recovery units for natural <span class="hlt">gas</span>-fired boilers are examined. The governing parameter affecting the performance and cost of surface-type condensing heat recovery heat <span class="hlt">exchangers</span> is the heat transfer surface area. When firing natural <span class="hlt">gas</span>, the heat recovery depth depends on the flue <span class="hlt">gas</span> temperature at the condenser outlet and determines the amount of condensed water vapor. The effect of the outlet flue <span class="hlt">gas</span> temperature in a heat recovery heat <span class="hlt">exchanger</span> on the additionally recovered heat power is studied. A correlation has been derived enabling one to determine the best heat recovery depth (or the final cooling temperature) maximizing the anticipated reduced annual profit of a power enterprise from implementation of energy-saving measures. Results of optimization are presented for a surface-type condensing <span class="hlt">gas</span>-air plate heat recovery heat <span class="hlt">exchanger</span> for the climatic conditions and the economic situation in Tomsk. The predictions demonstrate that it is economically feasible to design similar heat recovery heat <span class="hlt">exchangers</span> for a flue <span class="hlt">gas</span> outlet temperature of 10°C. In this case, the payback period for the investment in the heat recovery heat <span class="hlt">exchanger</span> will be 1.5 years. The effect of various factors on the optimal outlet flue <span class="hlt">gas</span> temperature was analyzed. Most climatic, economical, or technological factors have a minor effect on the best outlet temperature, which remains between 5 and 20°C when varying the affecting factors. The derived correlation enables us to preliminary estimate the outlet (final) flue <span class="hlt">gas</span> temperature that should be used in designing the heat transfer surface of a heat recovery heat <span class="hlt">exchanger</span> for a <span class="hlt">gas</span>-fired boiler as applied to the specific climatic conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.B53A0937M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.B53A0937M"><span>Using Riverboat-Mounted Eddy Covariance for Direct Measurements of Air-water <span class="hlt">Gas</span> <span class="hlt">Exchange</span> in Amazonia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miller, S. D.; Freitas, H.; Read, E.; Goulden, M. L.; Rocha, H.</p> <p>2007-12-01</p> <p><span class="hlt">Gas</span> evasion from Amazonian rivers and lakes to the atmosphere has been estimated to play an important role in the regional budget of carbon dioxide (Richey et al., 2002) and the global budget of methane (Melack et al., 2004). These flux estimates were calculated by combining remote sensing estimates of inundation area with water-side concentration gradients and <span class="hlt">gas</span> transfer rates (piston velocities) estimated primarily from floating chamber measurements (footprint ~1 m2). The uncertainty in these fluxes was large, attributed primarily to uncertainty in the <span class="hlt">gas</span> <span class="hlt">exchange</span> parameterization. Direct measurements of the <span class="hlt">gas</span> <span class="hlt">exchange</span> coefficient are needed to improve the parameterizations in these environments, and therefore reduce the uncertainty in fluxes. The micrometeorological technique of eddy covariance is attractive since it is a direct measurement of <span class="hlt">gas</span> <span class="hlt">exchange</span> that samples over a much larger area than floating chambers, and is amenable to use from a moving platform. We present eddy covariance carbon dioxide <span class="hlt">exchange</span> measurements made using a small riverboat in rivers and lakes in the central Amazon near Santarem, Para, Brazil. Water-side carbon dioxide concentration was measured in situ, and the <span class="hlt">gas</span> <span class="hlt">exchange</span> coefficient was calculated. We found the piston velocity at a site on the Amazon River to be similar to existing ocean-based parameterizations, whereas the piston velocity at a site on the Tapajos River was roughly a factor 5 higher. We hypothesize that the enhanced <span class="hlt">gas</span> <span class="hlt">exchange</span> at the Tapajos site was due to a shallow upwind fetch. Our results demonstrate the feasibility of boat-based eddy covariance on these rivers, and also the utility of a mobile platform to investigate spatial variability of <span class="hlt">gas</span> <span class="hlt">exchange</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018HMT....54.1951C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018HMT....54.1951C"><span>Performance of casting aluminum-silicon alloy condensing heating <span class="hlt">exchanger</span> for <span class="hlt">gas</span>-fired boiler</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cao, Weixue; Liu, Fengguo; You, Xue-yi</p> <p>2018-07-01</p> <p>Condensing <span class="hlt">gas</span> boilers are widely used due to their high heat efficiency, which comes from their ability to use the recoverable sensible heat and latent heat in flue <span class="hlt">gas</span>. The condensed water of the boiler exhaust has strong corrosion effect on the heat <span class="hlt">exchanger</span>, which restricts the further application of the condensing <span class="hlt">gas</span> boiler. In recent years, a casting aluminum-silicon alloy (CASA), which boasts good anti-corrosion properties, has been introduced to condensing hot water boilers. In this paper, the heat transfer performance, CO and NOx emission concentrations and CASA corrosion resistance of a heat <span class="hlt">exchanger</span> are studied by an efficiency bench test of the <span class="hlt">gas</span>-fired boiler. The experimental results are compared with heat <span class="hlt">exchangers</span> produced by Honeywell and Beka. The results show that the excess air coefficient has a significant effect on the heat efficiency and CO and NOx emission of the CASA water heater. When the excess air coefficient of the CASA <span class="hlt">gas</span> boiler is 1.3, the CO and NOx emission concentration of the flue <span class="hlt">gas</span> satisfies the design requirements, and the heat efficiency of water heater is 90.8%. In addition, with the increase of heat load rate, the heat transfer coefficient of the heat <span class="hlt">exchanger</span> and the heat efficiency of the water heater are increased. However, when the heat load rate is at 90%, the NOx emission in the exhaust <span class="hlt">gas</span> is the highest. Furthermore, when the temperature of flue <span class="hlt">gas</span> is below 57 °C, the condensation of water vapor occurs, and the pH of condensed water is in the 2.5 5.5 range. The study shows that CASA water heater has good corrosion resistance and a high heat efficiency of 88%. Compared with the heat <span class="hlt">exchangers</span> produced by Honeywell and Beka, there is still much work to do in optimizing and improving the water heater.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018HMT...tmp...25C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018HMT...tmp...25C"><span>Performance of casting aluminum-silicon alloy condensing heating <span class="hlt">exchanger</span> for <span class="hlt">gas</span>-fired boiler</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cao, Weixue; Liu, Fengguo; You, Xue-yi</p> <p>2018-01-01</p> <p>Condensing <span class="hlt">gas</span> boilers are widely used due to their high heat efficiency, which comes from their ability to use the recoverable sensible heat and latent heat in flue <span class="hlt">gas</span>. The condensed water of the boiler exhaust has strong corrosion effect on the heat <span class="hlt">exchanger</span>, which restricts the further application of the condensing <span class="hlt">gas</span> boiler. In recent years, a casting aluminum-silicon alloy (CASA), which boasts good anti-corrosion properties, has been introduced to condensing hot water boilers. In this paper, the heat transfer performance, CO and NOx emission concentrations and CASA corrosion resistance of a heat <span class="hlt">exchanger</span> are studied by an efficiency bench test of the <span class="hlt">gas</span>-fired boiler. The experimental results are compared with heat <span class="hlt">exchangers</span> produced by Honeywell and Beka. The results show that the excess air coefficient has a significant effect on the heat efficiency and CO and NOx emission of the CASA water heater. When the excess air coefficient of the CASA <span class="hlt">gas</span> boiler is 1.3, the CO and NOx emission concentration of the flue <span class="hlt">gas</span> satisfies the design requirements, and the heat efficiency of water heater is 90.8%. In addition, with the increase of heat load rate, the heat transfer coefficient of the heat <span class="hlt">exchanger</span> and the heat efficiency of the water heater are increased. However, when the heat load rate is at 90%, the NOx emission in the exhaust <span class="hlt">gas</span> is the highest. Furthermore, when the temperature of flue <span class="hlt">gas</span> is below 57 °C, the condensation of water vapor occurs, and the pH of condensed water is in the 2.5 5.5 range. The study shows that CASA water heater has good corrosion resistance and a high heat efficiency of 88%. Compared with the heat <span class="hlt">exchangers</span> produced by Honeywell and Beka, there is still much work to do in optimizing and improving the water heater.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/13382','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/13382"><span>Water use in forest canopy black cherry trees and its relationship to leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and environment</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>B. J. Joyce; K. C. Steiner; J. M. Skelly</p> <p>1996-01-01</p> <p>Models of canopy <span class="hlt">gas</span> <span class="hlt">exchange</span> are needed to connect leaf-level measurement to higher scales. Because of the correspondence between leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and water use, it may be possible to predict variation in leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> at the canopy level by monitoring rates of branch water use.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=47600&Lab=NHEERL&keyword=physiology+AND+stress&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=47600&Lab=NHEERL&keyword=physiology+AND+stress&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>JOINT ACTION OF O3 AND SO2 IN MODIFYING PLANT <span class="hlt">GAS</span> <span class="hlt">EXCHANGE</span></span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The joint action of O3 and SO2 stress on plants was investigated. <span class="hlt">Gas</span> <span class="hlt">exchange</span> measurements of O3, SO2, and H2O vapor were made for garden pea. Plants were grown under controlled environments; O3, SO2, H2O vapor fluxes were evaluated with a whole-plant <span class="hlt">gas</span> <span class="hlt">exchange</span> chamber using ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29938338','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29938338"><span>Calculation algorithms for breath-by-breath alveolar <span class="hlt">gas</span> <span class="hlt">exchange</span>: the unknowns!</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Golja, Petra; Cettolo, Valentina; Francescato, Maria Pia</p> <p>2018-06-25</p> <p>Several papers (algorithm papers) describe computational algorithms that assess alveolar breath-by-breath <span class="hlt">gas</span> <span class="hlt">exchange</span> by accounting for changes in lung <span class="hlt">gas</span> stores. It is unclear, however, if the effects of the latter are actually considered in literature. We evaluated dissemination of algorithm papers and the relevant provided information. The list of documents investigating exercise transients (in 1998-2017) was extracted from Scopus database. Documents citing the algorithm papers in the same period were analyzed in full text to check consistency of the relevant information provided. Less than 8% (121/1522) of documents dealing with exercise transients cited at least one algorithm paper; the paper of Beaver et al. (J Appl Physiol 51:1662-1675, 1981) was cited most often, with others being cited tenfold less. Among the documents citing the algorithm paper of Beaver et al. (J Appl Physiol 51:1662-1675, 1981) (N = 251), only 176 cited it for the application of their algorithm/s; in turn, 61% (107/176) of them stated the alveolar breath-by-breath <span class="hlt">gas</span> <span class="hlt">exchange</span> measurement, but only 1% (1/107) of the latter also reported the assessment of volunteers' functional residual capacity, a crucial parameter for the application of the algorithm. Information related to <span class="hlt">gas</span> <span class="hlt">exchange</span> was provided consistently in the methods and in the results in 1 of the 107 documents. Dissemination of algorithm papers in literature investigating exercise transients is by far narrower than expected. The information provided about the actual application of <span class="hlt">gas</span> <span class="hlt">exchange</span> algorithms is often inadequate and/or ambiguous. Some guidelines are provided that can help to improve the quality of future publications in the field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24484174','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24484174"><span>Oxo-<span class="hlt">exchange</span> of <span class="hlt">gas</span>-phase uranyl, neptunyl, and plutonyl with water and methanol.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lucena, Ana F; Odoh, Samuel O; Zhao, Jing; Marçalo, Joaquim; Schreckenbach, Georg; Gibson, John K</p> <p>2014-02-17</p> <p>A challenge in actinide chemistry is activation of the strong bonds in the actinyl ions, AnO2(+) and AnO2(2+), where An = U, Np, or Pu. Actinyl activation in oxo-<span class="hlt">exchange</span> with water in solution is well established, but the <span class="hlt">exchange</span> mechanisms are unknown. <span class="hlt">Gas</span>-phase actinyl oxo-<span class="hlt">exchange</span> is a means to probe these processes in detail for simple systems, which are amenable to computational modeling. <span class="hlt">Gas</span>-phase <span class="hlt">exchange</span> reactions of UO2(+), NpO2(+), PuO2(+), and UO2(2+) with water and methanol were studied by experiment and density functional theory (DFT); reported for the first time are experimental results for UO2(2+) and for methanol <span class="hlt">exchange</span>, as well as <span class="hlt">exchange</span> rate constants. Key findings are faster <span class="hlt">exchange</span> of UO2(2+) versus UO2(+) and faster <span class="hlt">exchange</span> with methanol versus water; faster <span class="hlt">exchange</span> of UO2(+) versus PuO2(+) was quantified. Computed potential energy profiles (PEPs) are in accord with the observed kinetics, validating the utility of DFT to model these <span class="hlt">exchange</span> processes. The seemingly enigmatic result of faster <span class="hlt">exchange</span> for uranyl, which has the strongest oxo-bonds, may reflect reduced covalency in uranyl as compared with plutonyl.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940007998','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940007998"><span>Sulfur <span class="hlt">gas</span> <span class="hlt">exchange</span> in Sphagnum-dominated wetlands</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hines, Mark E.; Demello, William Zamboni; Porter, Carolyn A.</p> <p>1992-01-01</p> <p>Sulfur gases are important components of the global cycle of S. They contribute to the acidity of precipitation and they influence global radiation balance and climate. The role of terrestrial sources of biogenic S and their effect on atmospheric chemistry remain as major unanswered questions in our understanding of the natural S cycle. The role of northern wetlands as sources and sinks of gaseous S was investigated by measuring rates of S <span class="hlt">gas</span> <span class="hlt">exchange</span> as a function of season, hydrologic conditions, and gradients in trophic status. The effects of inorganic S input on the production and emission of gaseous S were also investigated. Experiments were conducted in wetlands in New Hampshire, particularly a poor fen, fens within the Experimental Lakes Area (ELA) in Ontario, Canada and in freshwater and marine tundra. Emissions were determined using Teflon enclosures, <span class="hlt">gas</span> cryotrapping methods, and <span class="hlt">gas</span> chromatography (GC) with flame photometric detection. Dynamic (sweep flow) and static enclosures were employed. Dissolved gases were determined by <span class="hlt">gas</span> stripping followed by GC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006GeoRL..3314803Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006GeoRL..3314803Z"><span>Impacts of winter storms on air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Weiqing; Perrie, Will; Vagle, Svein</p> <p>2006-07-01</p> <p>The objective of this study is to investigate air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> during winter storms, using field measurements from Ocean Station Papa in the Northeast Pacific (50°N, 145°W). We show that increasing <span class="hlt">gas</span> transfer rates are coincident with increasing winds and deepening depth of bubble penetration, and that this process depends on sea state. Wave-breaking is shown to be an important factor in the <span class="hlt">gas</span> transfer velocity during the peaks of the storms, increasing the flux rates by up to 20%. <span class="hlt">Gas</span> transfer rates and concentrations can exhibit asymmetry, reflecting a sudden increase with the onset of a storm, and gradual recovery stages.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AdSpR..51..465W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AdSpR..51..465W"><span>Plant mineral nutrition, <span class="hlt">gas</span> <span class="hlt">exchange</span> and photosynthesis in space: A review</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wolff, S. A.; Coelho, L. H.; Zabrodina, M.; Brinckmann, E.; Kittang, A.-I.</p> <p>2013-02-01</p> <p>Successful growth and development of higher plants in space rely on adequate availability and uptake of water and nutrients, and efficient energy distribution through photosynthesis and <span class="hlt">gas</span> <span class="hlt">exchange</span>. In the present review, literature has been reviewed to assemble the relevant knowledge within space plant research for future planetary missions. Focus has been on fractional gravity, space radiation, magnetic fields and ultimately a combined effect of these factors on <span class="hlt">gas</span> <span class="hlt">exchange</span>, photosynthesis and transport of water and solutes. Reduced gravity prevents buoyancy driven thermal convection in the physical environment around the plant and alters transport and <span class="hlt">exchange</span> of gases and liquids between the plant and its surroundings. In space experiments, indications of root zone hypoxia have frequently been reported, but studies on the influences of the space environment on plant nutrition and water transport are limited or inconclusive. Some studies indicate that uptake of potassium is elevated when plants are grown under microgravity conditions. Based on the current knowledge, <span class="hlt">gas</span> <span class="hlt">exchange</span>, metabolism and photosynthesis seem to work properly in space when plants are provided with a well stirred atmosphere and grown at moderate light levels. Effects of space radiation on plant metabolism, however, have not been studied so far in orbit. Ground experiments indicated that shielding from the Earth's magnetic field alters plant <span class="hlt">gas</span> <span class="hlt">exchange</span> and metabolism, though more studies are required to understand the effects of magnetic fields on plant growth. It has been shown that plants can grow and reproduce in the space environment and adapt to space conditions. However, the influences of the space environment may result in a long term effect over multiple generations or have an impact on the plants' role as food and part of a regenerative life support system. Suggestions for future plant biology research in space are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24749994','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24749994"><span>Effect of impeller design and spacing on <span class="hlt">gas</span> <span class="hlt">exchange</span> in a percutaneous respiratory assist catheter.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jeffries, R Garrett; Frankowski, Brian J; Burgreen, Greg W; Federspiel, William J</p> <p>2014-12-01</p> <p>Providing partial respiratory assistance by removing carbon dioxide (CO2 ) can improve clinical outcomes in patients suffering from acute exacerbations of chronic obstructive pulmonary disease and acute respiratory distress syndrome. An intravenous respiratory assist device with a small (25 Fr) insertion diameter eliminates the complexity and potential complications associated with external blood circuitry and can be inserted by nonspecialized surgeons. The impeller percutaneous respiratory assist catheter (IPRAC) is a highly efficient CO2 removal device for percutaneous insertion to the vena cava via the right jugular or right femoral vein that utilizes an array of impellers rotating within a hollow-fiber membrane bundle to enhance <span class="hlt">gas</span> <span class="hlt">exchange</span>. The objective of this study was to evaluate the effects of new impeller designs and impeller spacing on <span class="hlt">gas</span> <span class="hlt">exchange</span> in the IPRAC using computational fluid dynamics (CFD) and in vitro deionized water <span class="hlt">gas</span> <span class="hlt">exchange</span> testing. A CFD <span class="hlt">gas</span> <span class="hlt">exchange</span> and flow model was developed to guide a progressive impeller design process. Six impeller blade geometries were designed and tested in vitro in an IPRAC device with 2- or 10-mm axial spacing and varying numbers of blades (2-5). The maximum CO2 removal efficiency (<span class="hlt">exchange</span> per unit surface area) achieved was 573 ± 8 mL/min/m(2) (40.1 mL/min absolute). The <span class="hlt">gas</span> <span class="hlt">exchange</span> rate was found to be largely independent of blade design and number of blades for the impellers tested but increased significantly (5-10%) with reduced axial spacing allowing for additional shaft impellers (23 vs. 14). CFD <span class="hlt">gas</span> <span class="hlt">exchange</span> predictions were within 2-13% of experimental values and accurately predicted the relative improvement with impellers at 2- versus 10-mm axial spacing. The ability of CFD simulation to accurately forecast the effects of influential design parameters suggests it can be used to identify impeller traits that profoundly affect facilitated <span class="hlt">gas</span> <span class="hlt">exchange</span>. Copyright © 2014 International Center for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.1419B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.1419B"><span>Atmosphere-ocean <span class="hlt">gas</span> <span class="hlt">exchange</span> based on radiocarbon data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Byalko, Alexey</p> <p>2014-05-01</p> <p>In recent decades, the intensity of global atmospheric convection has accelerated faster than climate warming; it is possible to judge this process from indirect data. Increasing ocean salinity contrasts provide evidence that evaporation has intensified [1]; sea surface wind velocities and wave heights have increased [2]. The CO2 <span class="hlt">gas</span> <span class="hlt">exchange</span> between the atmosphere and ocean must also simultaneously increase. Monthly measurements of atmospheric CO2 concentration have been published since 1958 [3], but directly measuring its fluxes from the atmosphere to the ocean and back is hardly possible. We show they can be reconstructed from 14C isotope concentration data. In the past century, two processes influenced the atmospheric 14C concentration in opposite directions: burning fossil fuels and testing nuclear weapons in the atmosphere. We compare the <span class="hlt">gas</span> <span class="hlt">exchange</span> theory with measurements of radiocarbon content in the atmosphere [4—6], which allows assessing the <span class="hlt">gas</span> <span class="hlt">exchange</span> quantitatively for the ocean to atmosphere and atmosphere to ocean fluxes separately for period 1960—2010 [7]. References 1. Durack P. J. and Wijffels S. E., J. Climate 23, 4342 (2010). 2. Young I. R., Sieger S., and Babanin A.V., Science 332, 451 (2011). 3. NOAA Earth System Research Laboratory Data: ftp://ftp.cmdl.noaa.gov/ccg/co2/trends/co2_mm_mlo.txt. 4. Nydal R., Lövseth K. // J. Geophys. Res. 1983. V. 88. P. 3579. 5. Levin I., Kromer B. // Radiocarbon. 1997. V. 39. P. 205. 6. Miller J.B., Lehman S.J., Montzka S.A., et al. // J. Geophys. Res. 2012. V. 117. D08302. 7. Byalko A.V. Doklady Physics, 2013. V. 58, 267-271.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1178521-guest-molecule-exchange-kinetics-ignik-sikumi-gas-hydrate-field-trial','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1178521-guest-molecule-exchange-kinetics-ignik-sikumi-gas-hydrate-field-trial"><span>Guest Molecule <span class="hlt">Exchange</span> Kinetics for the 2012 Ignik Sikumi <span class="hlt">Gas</span> Hydrate Field Trial</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>White, Mark D.; Lee, Won Suk</p> <p></p> <p>A commercially viable technology for producing methane from natural <span class="hlt">gas</span> hydrate reservoirs remains elusive. Short-term depressurization field tests have demonstrated the potential for producing natural <span class="hlt">gas</span> via dissociation of the clathrate structure, but the long-term performance of the depressurization technology ultimately requires a heat source to sustain the dissociation. A decade of laboratory experiments and theoretical studies have demonstrated the <span class="hlt">exchange</span> of pure CO2 and N2-CO2 mixtures with CH4 in sI <span class="hlt">gas</span> hydrates, yielding critical information about molecular mechanisms, recoveries, and <span class="hlt">exchange</span> kinetics. Findings indicated the potential for producing natural <span class="hlt">gas</span> with little to no production of water and rapidmore » <span class="hlt">exchange</span> kinetics, generating sufficient interest in the guest-molecule <span class="hlt">exchange</span> technology for a field test. In 2012 the U.S. DOE/NETL, ConocoPhillips Company, and Japan Oil, <span class="hlt">Gas</span> and Metals National Corporation jointly sponsored the first field trial of injecting a mixture of N2-CO2 into a CH4-hydrate bearing formation beneath the permafrost on the Alaska North Slope. Known as the Ignik Sikumi #1 <span class="hlt">Gas</span> Hydrate Field Trial, this experiment involved three stages: 1) the injection of a N2-CO2 mixture into a targeted hydrate-bearing layer, 2) a 4-day pressurized soaking period, and 3) a sustained depressurization and fluid production period. Data collected during the three stages of the field trial were made available after an extensive quality check. These data included continuous temperature and pressure logs, injected and recovered fluid compositions and volumes. The Ignik Sikumi #1 data set is extensive, but contains no direct evidence of the guest-molecule <span class="hlt">exchange</span> process. This investigation is directed at using numerical simulation to provide an interpretation of the collected data. A numerical simulator, STOMP-HYDT-KE, was recently completed that solves conservation equations for energy, water, mobile fluid guest molecules, and hydrate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1411972','SCIGOV-DOEDE'); return false;" href="https://www.osti.gov/servlets/purl/1411972"><span>Diurnal leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> survey, Feb2016-May2016, PA-SLZ, PA-PNM: Panama</span></a></p> <p><a target="_blank" href="http://www.osti.gov/dataexplorer">DOE Data Explorer</a></p> <p>Rogers, Alistair [Brookhaven National Lab; Serbin, Shawn [Brookhaven National Lab; Ely, Kim [Brookhaven National Lab; Wu, Jin [BNL; Wolfe, Brett [Smithsonian; Dickman, Turin [Los Alamos National Lab; Collins, Adam [Los Alamos National Lab; Detto, Matteo [Princeton; Grossiord, Charlotte [Los Alamos National Lab; McDowell, Nate [Los Alamos National Lab; Michaletz, Sean</p> <p>2017-01-01</p> <p>Diurnal leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> survey measured on sunlit canopy trees on a monthly basis from Feb to May 2016 at SLZ and PNM. This data was collected as part of the 2016 ENSO campaign. See related datasets (existing and future) for further sample details, leaf water potential, LMA, leaf spectra, other <span class="hlt">gas</span> <span class="hlt">exchange</span> and leaf chemistry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=223609&keyword=water+AND+gas+AND+exchange&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=223609&keyword=water+AND+gas+AND+exchange&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>Air-water <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Rates on a Large Impounded River Measured Using Floating Domes (Poster)</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>Mass balance models of dissolved gases in rivers typically serve as the basis for whole-system estimates of greenhouse <span class="hlt">gas</span> emission rates. An important component of these models is the <span class="hlt">exchange</span> of dissolved gases between air and water. Controls on <span class="hlt">gas</span> <span class="hlt">exchange</span> rates (K) have be...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24361970','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24361970"><span>Extracorporeal <span class="hlt">gas</span> <span class="hlt">exchange</span> and spontaneous breathing for the treatment of acute respiratory distress syndrome: an alternative to mechanical ventilation?*.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Langer, Thomas; Vecchi, Vittoria; Belenkiy, Slava M; Cannon, Jeremy W; Chung, Kevin K; Cancio, Leopoldo C; Gattinoni, Luciano; Batchinsky, Andriy I</p> <p>2014-03-01</p> <p>Venovenous extracorporeal <span class="hlt">gas</span> <span class="hlt">exchange</span> is increasingly used in awake, spontaneously breathing patients as a bridge to lung transplantation. Limited data are available on a similar use of extracorporeal <span class="hlt">gas</span> <span class="hlt">exchange</span> in patients with acute respiratory distress syndrome. The aim of this study was to investigate the use of extracorporeal <span class="hlt">gas</span> <span class="hlt">exchange</span> in awake, spontaneously breathing sheep with healthy lungs and with acute respiratory distress syndrome and describe the interactions between the native lung (healthy and diseased) and the artificial lung (extracorporeal <span class="hlt">gas</span> <span class="hlt">exchange</span>) in this setting. Laboratory investigation. Animal ICU of a governmental laboratory. Eleven awake, spontaneously breathing sheep on extracorporeal <span class="hlt">gas</span> <span class="hlt">exchange</span>. Sheep were studied before (healthy lungs) and after the induction of acute respiratory distress syndrome via IV injection of oleic acid. Six <span class="hlt">gas</span> flow settings (1-10 L/min), resulting in different amounts of extracorporeal CO2 removal (20-100% of total CO2 production), were tested in each animal before and after the injury. Respiratory variables and <span class="hlt">gas</span> <span class="hlt">exchange</span> were measured for every <span class="hlt">gas</span> flow setting. Both healthy and injured sheep reduced minute ventilation according to the amount of extracorporeal CO2 removal, up to complete apnea. However, compared with healthy sheep, sheep with acute respiratory distress syndrome presented significantly increased esophageal pressure variations (25 ± 9 vs 6 ± 3 cm H2O; p < 0.001), which could be reduced only with very high amounts of CO2 removal (> 80% of total CO2 production). Spontaneous ventilation of both healthy sheep and sheep with acute respiratory distress syndrome can be controlled via extracorporeal <span class="hlt">gas</span> <span class="hlt">exchange</span>. If this holds true in humans, extracorporeal <span class="hlt">gas</span> <span class="hlt">exchange</span> could be used in awake, spontaneously breathing patients with acute respiratory distress syndrome to support <span class="hlt">gas</span> <span class="hlt">exchange</span>. A deeper understanding of the pathophysiology of spontaneous breathing during acute respiratory</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=332572','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=332572"><span>Scaling leaf measurements to estimate cotton canopy <span class="hlt">gas</span> <span class="hlt">exchange</span></span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Diurnal leaf and canopy <span class="hlt">gas</span> <span class="hlt">exchange</span> of well watered field grown cotton were measured. Leaf measurements were made with a portable photosynthesis system and canopy measurements with open Canopy Evapo-Transpiration and Assimilation (CETA) systems. Leaf level measurements were arithmetically scaled to...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=respiratory&pg=5&id=EJ1004965','ERIC'); return false;" href="https://eric.ed.gov/?q=respiratory&pg=5&id=EJ1004965"><span>Pulmonary and Cutaneous O[subscript 2] <span class="hlt">Gas</span> <span class="hlt">Exchange</span>: A Student Laboratory Exercise in the Frog</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Tattersall, Glenn J.; Currie, Suzanne; LeBlanc, Danielle M.</p> <p>2013-01-01</p> <p><span class="hlt">Gas</span> <span class="hlt">exchange</span> in animals is ultimately diffusion based, generally occurring across dedicated respiratory organs. In many aquatic amphibians, however, multiple modes of <span class="hlt">gas</span> <span class="hlt">exchange</span> exist, allowing for the partitioning of O[subscript 2] uptake and CO[subscript 2] excretion between respiratory organs with different efficiencies. For example, due to…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26810432','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26810432"><span>Tuning a High Transmission Ion Guide to Prevent <span class="hlt">Gas</span>-Phase Proton <span class="hlt">Exchange</span> During H/D <span class="hlt">Exchange</span> MS Analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Guttman, Miklos; Wales, Thomas E; Whittington, Dale; Engen, John R; Brown, Jeffery M; Lee, Kelly K</p> <p>2016-04-01</p> <p>Hydrogen/deuterium <span class="hlt">exchange</span> (HDX) mass spectrometry (MS) for protein structural analysis has been adopted for many purposes, including biopharmaceutical development. One of the benefits of examining amide proton <span class="hlt">exchange</span> by mass spectrometry is that it can readily resolve different <span class="hlt">exchange</span> regimes, as evidenced by either binomial or bimodal isotope patterns. By careful analysis of the isotope pattern during <span class="hlt">exchange</span>, more insight can be obtained on protein behavior in solution. However, one must be sure that any observed bimodal isotope patterns are not artifacts of analysis and are reflective of the true behavior in solution. Sample carryover and certain stationary phases are known as potential sources of bimodal artifacts. Here, we describe an additional undocumented source of deuterium loss resulting in artificial bimodal patterns for certain highly charged peptides. We demonstrate that this phenomenon is predominantly due to <span class="hlt">gas</span>-phase proton <span class="hlt">exchange</span> between peptides and bulk solvent within the initial stages of high-transmission conjoined ion guides. Minor adjustments of the ion guide settings, as reported here, eliminate the phenomenon without sacrificing signal intensity. Such <span class="hlt">gas</span>-phase deuterium loss should be appreciated for all HDX-MS studies using such ion optics, even for routine studies not focused on interpreting bimodal spectra. Graphical Abstract ᅟ.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23957244','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23957244"><span>Differences in <span class="hlt">gas</span> <span class="hlt">exchange</span> contribute to habitat differentiation in Iberian columbines from contrasting light and water environments.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jaime, R; Serichol, C; Alcántara, J M; Rey, P J</p> <p>2014-03-01</p> <p>During photosynthesis, respiration and transpiration, <span class="hlt">gas</span> <span class="hlt">exchange</span> occurs via the stomata and so plants face a trade-off between maximising photosynthesis while minimising transpiration (expressed as water use efficiency, WUE). The ability to cope with this trade-off and regulate photosynthetic rate and stomatal conductance may be related to niche differentiation between closely related species. The present study explored this as a possible mechanism for habitat differentiation in Iberian columbines. The roles of irradiance and water stress were assessed to determine niche differentiation among Iberian columbines via distinct <span class="hlt">gas</span> <span class="hlt">exchange</span> processes. Photosynthesis-irradiance curves (P-I curves) were obtained for four taxa, and common garden experiments were conducted to examine plant responses to water and irradiance stress, by measuring instantaneous <span class="hlt">gas</span> <span class="hlt">exchange</span> and plant performance. <span class="hlt">Gas</span> <span class="hlt">exchange</span> was also measured in ten individuals using two to four field populations per taxon. The taxa had different P-I curves and <span class="hlt">gas</span> <span class="hlt">exchange</span> in the field. At the species level, water stress and irradiance explained habitat differentiation. Within each species, a combination of irradiance and water stress explained the between-subspecies habitat differentiation. Despite differences in stomatal conductance and CO2 assimilation, taxa did not have different WUE under field conditions, which suggests that the environment equally modifies photosynthesis and transpiration. The P-I curves, <span class="hlt">gas</span> <span class="hlt">exchange</span> in the field and plant responses to experimental water and irradiance stresses support the hypothesis that habitat differentiation is associated with differences among taxa in tolerance to abiotic stress mediated by distinct <span class="hlt">gas</span> <span class="hlt">exchange</span> responses. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26388365','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26388365"><span>Direct analysis of ultra-trace semiconductor <span class="hlt">gas</span> by inductively coupled plasma mass spectrometry coupled with <span class="hlt">gas</span> to particle conversion-<span class="hlt">gas</span> <span class="hlt">exchange</span> technique.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ohata, Masaki; Sakurai, Hiromu; Nishiguchi, Kohei; Utani, Keisuke; Günther, Detlef</p> <p>2015-09-03</p> <p>An inductively coupled plasma mass spectrometry (ICPMS) coupled with <span class="hlt">gas</span> to particle conversion-<span class="hlt">gas</span> <span class="hlt">exchange</span> technique was applied to the direct analysis of ultra-trace semiconductor <span class="hlt">gas</span> in ambient air. The ultra-trace semiconductor gases such as arsine (AsH3) and phosphine (PH3) were converted to particles by reaction with ozone (O3) and ammonia (NH3) gases within a <span class="hlt">gas</span> to particle conversion device (GPD). The converted particles were directly introduced and measured by ICPMS through a <span class="hlt">gas</span> <span class="hlt">exchange</span> device (GED), which could penetrate the particles as well as <span class="hlt">exchange</span> to Ar from either non-reacted gases such as an air or remaining gases of O3 and NH3. The particle size distribution of converted particles was measured by scanning mobility particle sizer (SMPS) and the results supported the elucidation of particle agglomeration between the particle converted from semiconductor <span class="hlt">gas</span> and the particle of ammonium nitrate (NH4NO3) which was produced as major particle in GPD. Stable time-resolved signals from AsH3 and PH3 in air were obtained by GPD-GED-ICPMS with continuous <span class="hlt">gas</span> introduction; however, the slightly larger fluctuation, which could be due to the ionization fluctuation of particles in ICP, was observed compared to that of metal carbonyl <span class="hlt">gas</span> in Ar introduced directly into ICPMS. The linear regression lines were obtained and the limits of detection (LODs) of 1.5 pL L(-1) and 2.4 nL L(-1) for AsH3 and PH3, respectively, were estimated. Since these LODs revealed sufficiently lower values than the measurement concentrations required from semiconductor industry such as 0.5 nL L(-1) and 30 nL L(-1) for AsH3 and PH3, respectively, the GPD-GED-ICPMS could be useful for direct and high sensitive analysis of ultra-trace semiconductor <span class="hlt">gas</span> in air. Copyright © 2015 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29058415','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29058415"><span>Online Simultaneous Hydrogen/Deuterium <span class="hlt">Exchange</span> of Multitarget <span class="hlt">Gas</span>-Phase Molecules by Electrospray Ionization Mass Spectrometry Coupled with <span class="hlt">Gas</span> Chromatography.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jeong, Eun Sook; Cha, Eunju; Cha, Sangwon; Kim, Sunghwan; Oh, Han Bin; Kwon, Oh-Seung; Lee, Jaeick</p> <p>2017-11-21</p> <p>In this study, a hydrogen/deuterium (H/D) <span class="hlt">exchange</span> method using <span class="hlt">gas</span> chromatography-electrospray ionization/mass spectrometry (GC-ESI/MS) was first investigated as a novel tool for online H/D <span class="hlt">exchange</span> of multitarget analytes. The GC and ESI source were combined with a homemade heated column transfer line. GC-ESI/MS-based H/D <span class="hlt">exchange</span> occurs in an atmospheric pressure ion source as a result of reacting the <span class="hlt">gas</span>-phase analyte eluted from GC with charged droplets of deuterium oxide infused as the ESI spray solvent. The consumption of the deuterated solvent at a flow rate of 2 μL min -1 was more economical than that in online H/D <span class="hlt">exchange</span> methods reported to date. In-ESI-source H/D <span class="hlt">exchange</span> by GC-ESI/MS was applied to 11 stimulants with secondary amino or hydroxyl groups. After H/D <span class="hlt">exchange</span>, the spectra of the stimulants showed unexchanged, partially <span class="hlt">exchanged</span>, and fully <span class="hlt">exchanged</span> ions showing various degrees of <span class="hlt">exchange</span>. The relative abundances corrected for naturally occurring isotopes of the fully <span class="hlt">exchanged</span> ions of stimulants, except for etamivan, were in the range 24.3-85.5%. Methylephedrine and cyclazodone showed low H/D <span class="hlt">exchange</span> efficiency under acidic, neutral, and basic spray solvent conditions and nonexchange for etamivan with an acidic phenolic OH group. The in-ESI-source H/D <span class="hlt">exchange</span> efficiency by GC-ESI/MS was sufficient to determine the number of hydrogen by elucidation of fragmentation from the spectrum. Therefore, this online H/D <span class="hlt">exchange</span> technique using GC-ESI/MS has potential as an alternative method for simultaneous H/D <span class="hlt">exchange</span> of multitarget analytes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22675191','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22675191"><span>Respiratory dynamics of discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> in the tracheal system of the desert locust, Schistocerca gregaria.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Groenewald, Berlizé; Hetz, Stefan K; Chown, Steven L; Terblanche, John S</p> <p>2012-07-01</p> <p><span class="hlt">Gas</span> <span class="hlt">exchange</span> dynamics in insects is of fundamental importance to understanding evolved variation in breathing patterns, such as discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> cycles (DGCs). Most insects do not rely solely on diffusion for the <span class="hlt">exchange</span> of respiratory gases but may also make use of respiratory movements (active ventilation) to supplement <span class="hlt">gas</span> <span class="hlt">exchange</span> at rest. However, their temporal dynamics have not been widely investigated. Here, intratracheal pressure, V(CO2) and body movements of the desert locust Schistocerca gregaria were measured simultaneously during the DGC and revealed several important aspects of <span class="hlt">gas</span> <span class="hlt">exchange</span> dynamics. First, S. gregaria employs two different ventilatory strategies, one involving dorso-ventral contractions and the other longitudinal telescoping movements. Second, although a true spiracular closed (C)-phase of the DGC could be identified by means of subatmospheric intratracheal pressure recordings, some CO(2) continued to be released. Third, strong pumping actions do not necessarily lead to CO(2) release and could be used to ensure mixing of gases in the closed tracheal system, or enhance water vapour reabsorption into the haemolymph from fluid-filled tracheole tips by increasing the hydrostatic pressure or forcing fluid into the haemocoel. Finally, this work showed that the C-phase of the DGC can occur at any pressure. These results provide further insights into the mechanistic basis of insect <span class="hlt">gas</span> <span class="hlt">exchange</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17670465','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17670465"><span>Pulmonary hemodynamics and <span class="hlt">gas</span> <span class="hlt">exchange</span> in off pump coronary artery bypass grafting.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vedin, Jenny; Jensen, Ulf; Ericsson, Anders; Samuelsson, Sten; Vaage, Jarle</p> <p>2005-10-01</p> <p>To investigate the influence of cardiopulmonary bypass on pulmonary hemodynamics and <span class="hlt">gas</span> <span class="hlt">exchange</span>. Low risk patients admitted for elective coronary artery bypass grafting were randomized to either on (n=25) or off pump (n=25) surgery. Central hemodynamics, <span class="hlt">gas</span> <span class="hlt">exchange</span>, and venous admixture were studied during and up to 20 h after surgery. There was no difference in pulmonary vascular resistance index (P=0.16), right ventricular stroke work index (P>0.2), mean pulmonary artery pressure (P>0.2) or pulmonary capillary wedge pressure (P>0.2) between groups. Soon after surgery there was a tendency towards higher cardiac index (P=0.07) in the off pump group. Arterial oxygen tension (P>0.2), hematocrit (P>0.2), venous admixture (P>0.2), and arterial-venous oxygen content difference (P=0.12) did not differ between groups. This prospective, randomized study showed no difference in pulmonary hemodynamics, pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span>, and venous admixture, in low risk patients undergoing off pump compared to on pump coronary artery bypass surgery.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22679801','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22679801"><span>[The variability of respiratory pattern and <span class="hlt">gas</span> <span class="hlt">exchange</span>].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Grishin, O V; Grishin, V G; Kovalenko, Iu V</p> <p>2012-01-01</p> <p>It is known, that spectral analysis of heart rate and respiratory variability allows to find out the very low frequency (VLF) rhythm. However it is not known, it is necessary to carry this rhythm to what type of wave processes. The purpose of the present researches was to study the respiratory variability and the variability of <span class="hlt">gas</span> <span class="hlt">exchange</span> parameters. 10 healthy subjects have been surveyed. The pneumogramms within 30 minutes spent record, and then a method "breath-by-breath" within 30 minutes registered <span class="hlt">gas</span> <span class="hlt">exchange</span> parameters (Ve--lung ventilation, V(O2) -O2 consumption and other parameters). Fast Fourier transform method has found out two groups of the basic peaks. The first--in a range 0.2-0.3 Hz (a time cycle--3-5 s), that corresponds respiratory frequency which size at subjects varied from 12 to 20 per minute. The second--in a range 0.002-0.0075 Hz, that corresponds VLF diapason (a time cycle--1-3.5 minutes). At the analysis pneumogramms rhythms in the same ranges have been established. The carried out researches allow to draw a conclusion on steady character of wave process in a VLF-range. It can be carried to quasi-periodic oscillations type. First oscillator or respiratory frequency it is formed by means of mechanisms of chemoreception. Considering, that V(O2) and V(CO2) are function energy <span class="hlt">exchange</span>, it is possible to believe, what exactly energy demand define the second oscillator.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28010808','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28010808"><span>Acute effects of temperature and hypercarbia on cutaneous and branchial <span class="hlt">gas</span> <span class="hlt">exchange</span> in the South American lungfish, Lepidosiren paradoxa.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zena, Lucas A; Bícego, Kênia C; da Silva, Glauber S F; Giusti, Humberto; Glass, Mogens L; Sanchez, Adriana P</p> <p>2017-01-01</p> <p>The South American lungfish, Lepidosiren paradoxa inhabits seasonal environments in the Central Amazon and Paraná-Paraguay basins that undergo significant oscillations in temperature throughout the year. They rely on different <span class="hlt">gas</span> <span class="hlt">exchange</span> organs, such as gills and skin for aquatic <span class="hlt">gas</span> <span class="hlt">exchange</span> while their truly bilateral lungs are responsible for aerial <span class="hlt">gas</span> <span class="hlt">exchange</span>; however, there are no data available on the individual contributions of the skin and the gills to total aquatic <span class="hlt">gas</span> <span class="hlt">exchange</span> in L. paradoxa. Thus, in the present study we quantify the relative contributions of skin and gills on total aquatic <span class="hlt">gas</span> <span class="hlt">exchange</span> during warm (35°C) and cold exposure (20°C) in addition to the effects of aerial and aquatic hypercarbia on aquatic <span class="hlt">gas</span> <span class="hlt">exchange</span> and gill ventilation rate (f G ; 25°C), respectively. Elevated temperature (35°C) caused a significant increase in the contribution of cutaneous (from 0.61±0.13 to 1.34±0.26ml. STPD.h -1 kg -1 ) and branchial (from 0.54±0.17 to 1.73±0.53ml. STPD.h -1 kg -1 ) <span class="hlt">gas</span> <span class="hlt">exchange</span> for V̇CO 2 relative to the lower temperature (20°C), while V̇O 2 remained relatively unchanged. L. paradoxa exhibited a greater branchial contribution in relation to total aquatic <span class="hlt">gas</span> <span class="hlt">exchange</span> at lower temperatures (20 and 25°C) for oxygen uptake. Aerial hypercarbia decreased branchial V̇O 2 whereas branchial V̇CO 2 was significantly increased. Progressive increases in aquatic hypercarbia did not affect f G . This response is in contrast to increases in pulmonary ventilation that may offset any increase in arterial partial pressure of CO 2 owing to CO 2 loading through the animals' branchial surface. Thus, despite their reduced contribution to total <span class="hlt">gas</span> <span class="hlt">exchange</span>, cutaneous and branchial <span class="hlt">gas</span> <span class="hlt">exchange</span> in L. paradoxa can be significantly affected by temperature and aerial hypercarbia. Copyright © 2016 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20926272','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20926272"><span>The impact of <span class="hlt">gas</span> <span class="hlt">exchange</span> measurement during exercise in pulmonary sarcoidosis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kollert, Florian; Geck, Barbara; Suchy, Rolf; Jörres, Rudolf A; Arzt, Michael; Heidinger, Dominic; Hamer, Okka W; Prasse, Antje; Müller-Quernheim, Joachim; Pfeifer, Michael; Budweiser, Stephan</p> <p>2011-01-01</p> <p>Pulmonary sarcoidosis shows a remarkable heterogeneity of phenotypes ranging from bihilar lymphadenopathy to progressive fibrosis. Individual disease assessment is demanding and requires sensible, practical measures. We tested whether <span class="hlt">gas</span> <span class="hlt">exchange</span> measurements during exercise reflects disease activity and clinical course in sarcoidosis. In 149 patients with proven pulmonary sarcoidosis the alveolar-arterial oxygen pressure gradient (P(A-a)O(2)) during exercise was assessed and compared with chest X-ray typing, pulmonary function, single breath-diffusing capacity for carbon monoxide (DL(CO)), serological markers, cell composition of bronchoalveolar lavage fluid (BALF) and clinical course. Patients were categorized according to thresholds of P(A-a)O(2) during exercise. Chest X-ray typing, pulmonary function, DL(CO) and the need for immunosuppressive treatment differed between the disease categories based on P(A-a)O(2) during exercise (p < 0.0001 each). Patients with an impairment of <span class="hlt">gas</span> <span class="hlt">exchange</span> during exercise also showed elevated levels of neopterin (p = 0.002) and higher percentages of neutrophils (p = 0.013) and eosinophils (p < 0.0001) in BALF. Multivariate regression analysis showed that forced vital capacity (FVC) (p = 0.009) and P(A-a)O(2) during exercise (p < 0.0001) were independently associated with a prolonged need for immunosuppressive treatment (>1 year), but not DL(CO). About 50% (n = 75) of the study population showed a normal spirometry. Even in this subgroup 23% had an impaired <span class="hlt">gas</span> <span class="hlt">exchange</span> during exercise, which correlated with chest X-ray types (p < 0.0001) and the need for immunosuppressive treatment (p < 0.005). Impaired <span class="hlt">gas</span> <span class="hlt">exchange</span> during exercise reflects disease activity and its extent and is associated with a prolonged need for immunosuppressive treatment during follow-up in patients with pulmonary sarcoidosis. Copyright © 2010 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880038508&hterms=water+gas+exchange&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dwater%2Bgas%2Bexchange','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880038508&hterms=water+gas+exchange&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dwater%2Bgas%2Bexchange"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span> on Mono Lake and Crowley Lake, California</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wanninkhof, Rik; Ledwell, James R.; Broecker, Wallace S.</p> <p>1987-01-01</p> <p><span class="hlt">Gas</span> <span class="hlt">exchange</span> coefficients (k) have been determined for freshwater Crowley Lake and saline Mono Lake through the use of a man-made purposefully injected <span class="hlt">gas</span>, SF6. The concentration decreased from an initial value of 40 to 4 pmol/L for Mono Lake and from 20 to 1 pmol/L for Crowley lake over a period of 6 wks. Wind-speed (u) records from anemometers on the shore of each lake made it possible to determine the relationship between k and u. The average u and k values for the experiment were identical for the two lakes, despite the large chemical differences. It is estimated that, for the u values observed over Mono Lake from July to December 1984, the <span class="hlt">exchange</span> of CO2 occurred 2.5 times faster than without chemical enhancement. This is a factor of 4 lower than needed to explain the high invasion rate of C-14 produced by nuclear bomb tests.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3046576','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3046576"><span>A Three-Dimensional Multiscale Model for <span class="hlt">Gas</span> <span class="hlt">Exchange</span> in Fruit1[C][W][OA</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ho, Quang Tri; Verboven, Pieter; Verlinden, Bert E.; Herremans, Els; Wevers, Martine; Carmeliet, Jan; Nicolaï, Bart M.</p> <p>2011-01-01</p> <p>Respiration of bulky plant organs such as roots, tubers, stems, seeds, and fruit depends very much on oxygen (O2) availability and often follows a Michaelis-Menten-like response. A multiscale model is presented to calculate <span class="hlt">gas</span> <span class="hlt">exchange</span> in plants using the microscale geometry of the tissue, or vice versa, local concentrations in the cells from macroscopic <span class="hlt">gas</span> concentration profiles. This approach provides a computationally feasible and accurate analysis of cell metabolism in any plant organ during hypoxia and anoxia. The predicted O2 and carbon dioxide (CO2) partial pressure profiles compared very well with experimental data, thereby validating the multiscale model. The important microscale geometrical features are the shape, size, and three-dimensional connectivity of cells and air spaces. It was demonstrated that the <span class="hlt">gas-exchange</span> properties of the cell wall and cell membrane have little effect on the cellular <span class="hlt">gas</span> <span class="hlt">exchange</span> of apple (Malus × domestica) parenchyma tissue. The analysis clearly confirmed that cells are an additional route for CO2 transport, while for O2 the intercellular spaces are the main diffusion route. The simulation results also showed that the local <span class="hlt">gas</span> concentration gradients were steeper in the cells than in the surrounding air spaces. Therefore, to analyze the cellular metabolism under hypoxic and anoxic conditions, the microscale model is required to calculate the correct intracellular concentrations. Understanding the O2 response of plants and plant organs thus not only requires knowledge of external conditions, dimensions, <span class="hlt">gas-exchange</span> properties of the tissues, and cellular respiration kinetics but also of microstructure. PMID:21224337</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=547498','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=547498"><span><span class="hlt">Gas</span> <span class="hlt">Exchange</span> of Algae</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ammann, Elizabeth C. B.; Fraser-Smith, Antony</p> <p>1968-01-01</p> <p>A single culture of Chlorella pyrenoidosa (700 ml) was grown continuously under uniform environmental conditions for a period of 11 months. During this time, the culture remained uncontaminated and its oxygen production, carbon dioxide consumption, and photosynthetic quotient (PQ = CO2/O2) were monitored on a 24-hr basis. The <span class="hlt">gas</span> <span class="hlt">exchange</span> characteristics of the alga were found to be extremely reliable; the average oxygen production was 1.21 ± 0.03 ml per min, the carbon dioxide consumption was 1.09 ± 0.03 ml per min, and the PQ was 0.90 ± 0.01 when changes in both lamp intensity and instrument accuracy were taken into consideration. Such long-term dependability in the production of oxygen, consumption of carbon dioxide, and maintenance of a uniform PQ warrants the use of C. pyrenoidosa in a regenerative life support system for space travel. PMID:4385488</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70020226','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70020226"><span><span class="hlt">Abnormal</span> pressure in hydrocarbon environments</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Law, B.E.; Spencer, C.W.</p> <p>1998-01-01</p> <p><span class="hlt">Abnormal</span> pressures, pressures above or below hydrostatic pressures, occur on all continents in a wide range of geological conditions. According to a survey of published literature on <span class="hlt">abnormal</span> pressures, compaction disequilibrium and hydrocarbon generation are the two most commonly cited causes of <span class="hlt">abnormally</span> high pressure in petroleum provinces. In young (Tertiary) deltaic sequences, compaction disequilibrium is the dominant cause of <span class="hlt">abnormal</span> pressure. In older (pre-Tertiary) lithified rocks, hydrocarbon generation, aquathermal expansion, and tectonics are most often cited as the causes of <span class="hlt">abnormal</span> pressure. The association of <span class="hlt">abnormal</span> pressures with hydrocarbon accumulations is statistically significant. Within <span class="hlt">abnormally</span> pressured reservoirs, empirical evidence indicates that the bulk of economically recoverable oil and <span class="hlt">gas</span> occurs in reservoirs with pressure gradients less than 0.75 psi/ft (17.4 kPa/m) and there is very little production potential from reservoirs that exceed 0.85 psi/ft (19.6 kPa/m). <span class="hlt">Abnormally</span> pressured rocks are also commonly associated with unconventional <span class="hlt">gas</span> accumulations where the pressuring phase is <span class="hlt">gas</span> of either a thermal or microbial origin. In underpressured, thermally mature rocks, the affected reservoirs have most often experienced a significant cooling history and probably evolved from an originally overpressured system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AIPC.1879b0006C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AIPC.1879b0006C"><span>Devise of an exhaust <span class="hlt">gas</span> heat <span class="hlt">exchanger</span> for a thermal oil heater in a palm oil refinery plant</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chucherd, Panom; Kittisupakorn, Paisan</p> <p>2017-08-01</p> <p>This paper presents the devise of an exhaust <span class="hlt">gas</span> heat <span class="hlt">exchanger</span> for waste heat recovery of the exhausted flue <span class="hlt">gas</span> of palm oil refinery plant. This waste heat can be recovered by installing an economizer to heat the feed water which can save the fuel consumption of the coal fired steam boiler and the outlet temperature of flue <span class="hlt">gas</span> will be controlled in order to avoid the acid dew point temperature and protect the filter bag. The decrease of energy used leads to the reduction of CO2 emission. Two designed economizer studied in this paper are <span class="hlt">gas</span> in tube and water in tube. The <span class="hlt">gas</span> in tube <span class="hlt">exchanger</span> refers to the shell and tube heat <span class="hlt">exchanger</span> which the flue <span class="hlt">gas</span> flows in tube; this designed <span class="hlt">exchanger</span> is used in the existing unit. The new designed water in tube refers to the shell and tube heat <span class="hlt">exchanger</span> which the water flows in the tube; this designed <span class="hlt">exchanger</span> is proposed for new implementation. New economizer has the overall coefficient of heat transfer of 19.03 W/m2.K and the surface heat transfer area of 122 m2 in the optimized case. Experimental results show that it is feasible to install economizer in the exhaust flue <span class="hlt">gas</span> system between the air preheater and the bag filter, which has slightly disadvantage effect in the system. The system can raise the feed water temperature from 40 to 104°C and flow rate 3.31 m3/h, the outlet temperature of flue <span class="hlt">gas</span> is maintained about 130 °C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984STIN...8529211E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984STIN...8529211E"><span>Development of corrosion resistant heat <span class="hlt">exchangers</span> for flue <span class="hlt">gas</span> desulfurization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ernst, E.; Lorentz, R.</p> <p>1984-12-01</p> <p>A glass lining as protection against corrosion in flue <span class="hlt">gas</span> desulfurization plants was developed. Glasses were evaluated under corrosive attack of fluoride-containing acids. The corrosion properties of one-layer and two-layer glass enamels are optimized. Two-layer systems always show better resistance and longer life. The optimized glass linings were tested in a power plant. Manufacturing principles for glass-lined heat <span class="hlt">exchanger</span> elements are derived. The optimized glasses may be used as protective lining design for heat <span class="hlt">exchangers</span> or parts of them.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1711535S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1711535S"><span>Estimating <span class="hlt">gas</span> <span class="hlt">exchange</span> of CO2 and CH4 between headwater systems and the atmosphere in Southwest Sweden</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Somlai, Celia; Natchimuthu, Sivakiruthika; Bastviken, David; Lorke, Andreas</p> <p>2015-04-01</p> <p>Quantifying the role of inland water systems in terms of carbon sinks and sources and their connection to the terrestrial ecosystems and landscapes is fundamental for improving the balance approach of regional and global carbon budgets. Recent research showed that freshwater bodies emit significant amounts of CO2 and CH4 into the atmosphere. The extent of the emissions from small streams and headwaters, however, remains uncertain due to a limited availability of data. Studies have shown that headwater systems receive most of the terrestrial organic carbon, have the highest dissolved CO2 concentration and the highest <span class="hlt">gas</span> <span class="hlt">exchange</span> velocities and cover the largest fractional surface area within fluvial networks. The <span class="hlt">gas</span> <span class="hlt">exchange</span> between inland waters and the atmosphere is controlled by two factors: the difference between the dissolved <span class="hlt">gas</span> concentration and its atmospheric equilibrium concentration, and the <span class="hlt">gas</span> <span class="hlt">exchange</span> velocity. The direct measurement of the dissolved <span class="hlt">gas</span> concentration of greenhouse gases can be measured straightforwardly, for example, by <span class="hlt">gas</span> chromatography from headspace extraction of water sample. In contrast, direct measurement of <span class="hlt">gas</span> <span class="hlt">exchange</span> velocity is more complex and time consuming, as simultaneous measurements with a volatile and nonvolatile inert tracer <span class="hlt">gas</span> are needed. Here we analyze measurements of <span class="hlt">gas</span> <span class="hlt">exchange</span> velocities, concentrations and fluxes of dissolved CO2 and CH4, as well as loads of total organic and inorganic carbon in 10 reaches in headwater streams in Southwest Sweden. We compare the <span class="hlt">gas</span> <span class="hlt">exchange</span> velocities measured directly through tracer injections with those estimated through various empirical approaches, which are based on modelled and measured current velocity, stream depth and slope. Furthermore, we estimate the resulting uncertainties of the flux estimates. We also present different time series of dissolved CO2, CH4 and O2 concentration, water temperature, barometric pressure, electro conductivity, and pH values</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70164484','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70164484"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span> rates across the sediment-water and air-water interfaces in south San Francisco Bay</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hartman, Blayne; Hammond, Douglas E.</p> <p>1984-01-01</p> <p>Radon 222 concentrations in the water and sedimentary columns and radon <span class="hlt">exchange</span> rates across the sediment-water and air-water interfaces have been measured in a section of south San Francisco Bay. Two independent methods have been used to determine sediment-water <span class="hlt">exchange</span> rates, and the annual averages of these methods agree within the uncertainty of the determinations, about 20%. The annual average of benthic fluxes from shoal areas is nearly a factor of 2 greater than fluxes from the channel areas. Fluxes from the shoal and channel areas exceed those expected from simple molecular diffusion by factors of 4 and 2, respectively, apparently due to macrofaunal irrigation. Values of the <span class="hlt">gas</span> transfer coefficient for radon <span class="hlt">exchange</span> across the air-water interface were determined by constructing a radon mass balance for the water column and by direct measurement using floating chambers. The chamber method appears to yield results which are too high. Transfer coefficients computed using the mass balance method range from 0.4 m/day to 1.8 m/day, with a 6-year average of 1.0 m/day. <span class="hlt">Gas</span> <span class="hlt">exchange</span> is linearly dependent upon wind speed over a wind speed range of 3.2–6.4 m/s, but shows no dependence upon current velocity. <span class="hlt">Gas</span> transfer coefficients predicted from an empirical relationship between <span class="hlt">gas</span> <span class="hlt">exchange</span> rates and wind speed observed in lakes and the oceans are within 30% of the coefficients determined from the radon mass balance and are considerably more accurate than coefficients predicted from theoretical <span class="hlt">gas</span> <span class="hlt">exchange</span> models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27..874S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27..874S"><span>Observational Studies of Parameters Influencing Air-sea <span class="hlt">Gas</span> <span class="hlt">Exchange</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schimpf, U.; Frew, N. M.; Bock, E. J.; Hara, T.; Garbe, C. S.; Jaehne, B.</p> <p></p> <p>A physically-based modeling of the air-sea <span class="hlt">gas</span> transfer that can be used to predict the <span class="hlt">gas</span> transfer rates with sufficient accuracy as a function of micrometeorological parameters is still lacking. State of the art are still simple <span class="hlt">gas</span> transfer rate/wind speed relationships. Previous measurements from Coastal Ocean Experiment in the Atlantic revealed positive correlations between mean square slope, near surface turbulent dis- sipation, and wind stress. It also demonstrated a strong negative correlation between mean square slope and the fluorescence of surface-enriched colored dissolved organic matter. Using heat as a proxy tracer for gases the <span class="hlt">exchange</span> process at the air/water interface and the micro turbulence at the water surface can be investigated. The anal- ysis of infrared image sequences allow the determination of the net heat flux at the ocean surface, the temperature gradient across the air/sea interface and thus the heat transfer velocity and <span class="hlt">gas</span> transfer velocity respectively. Laboratory studies were carried out in the new Heidelberg wind-wave facility AELOTRON. Direct measurements of the Schmidt number exponent were done in conjunction with classical mass balance methods to estimate the transfer velocity. The laboratory results allowed to validate the basic assumptions of the so called controlled flux technique by applying differ- ent tracers for the <span class="hlt">gas</span> <span class="hlt">exchange</span> in a large Schmidt number regime. Thus a modeling of the Schmidt number exponent is able to fill the gap between laboratory and field measurements field. Both, the results from the laboratory and the field measurements should be able to give a further understanding of the mechanisms controlling the trans- port processes across the aqueous boundary layer and to relate the forcing functions to parameters measured by remote sensing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10970675','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10970675"><span>Turbulence and wave breaking effects on air-water <span class="hlt">gas</span> <span class="hlt">exchange</span></span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Boettcher; Fineberg; Lathrop</p> <p>2000-08-28</p> <p>We present an experimental characterization of the effects of turbulence and breaking gravity waves on air-water <span class="hlt">gas</span> <span class="hlt">exchange</span> in standing waves. We identify two regimes that govern aeration rates: turbulent transport when no wave breaking occurs and bubble dominated transport when wave breaking occurs. In both regimes, we correlate the qualitative changes in the aeration rate with corresponding changes in the wave dynamics. In the latter regime, the strongly enhanced aeration rate is correlated with measured acoustic emissions, indicating that bubble creation and dynamics dominate air-water <span class="hlt">exchange</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720047210&hterms=exchange+theory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dexchange%2Btheory','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720047210&hterms=exchange+theory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dexchange%2Btheory"><span>The <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Experiment for life detection - The Viking Mars Lander.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Oyama, V. I.</p> <p>1972-01-01</p> <p>The <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Experiment of the Viking mission accepts a sample of Martian soil, incubates this soil with nutrient medium, and periodically samples the enclosed atmosphere over this soil for the gases H2, N2, O2, Kr, and CO2. These gases are analyzed by an automated <span class="hlt">gas</span> chromatograph, and the data are transmitted to earth. The design of the experiment and the qualitative and quantitative changes, if any, of <span class="hlt">gas</span> composition should allow conclusions to be made on the presence of life on Mars. Data and theory substantiating this approach are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23461476','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23461476"><span>Regulation and acclimation of leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> in a piñon-juniper woodland exposed to three different precipitation regimes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Limousin, Jean-Marc; Bickford, Christopher P; Dickman, Lee T; Pangle, Robert E; Hudson, Patrick J; Boutz, Amanda L; Gehres, Nathan; Osuna, Jessica L; Pockman, William T; McDowell, Nate G</p> <p>2013-10-01</p> <p>Leaf <span class="hlt">gas-exchange</span> regulation plays a central role in the ability of trees to survive drought, but forecasting the future response of <span class="hlt">gas</span> <span class="hlt">exchange</span> to prolonged drought is hampered by our lack of knowledge regarding potential acclimation. To investigate whether leaf <span class="hlt">gas-exchange</span> rates and sensitivity to drought acclimate to precipitation regimes, we measured the seasonal variations of leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> in a mature piñon-juniper Pinus edulis-Juniperus monosperma woodland after 3 years of precipitation manipulation. We compared trees receiving ambient precipitation with those in an irrigated treatment (+30% of ambient precipitation) and a partial rainfall exclusion (-45%). Treatments significantly affected leaf water potential, stomatal conductance and photosynthesis for both isohydric piñon and anisohydric juniper. Leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> acclimated to the precipitation regimes in both species. Maximum <span class="hlt">gas-exchange</span> rates under well-watered conditions, leaf-specific hydraulic conductance and leaf water potential at zero photosynthetic assimilation all decreased with decreasing precipitation. Despite their distinct drought resistance and stomatal regulation strategies, both species experienced hydraulic limitation on leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> when precipitation decreased, leading to an intraspecific trade-off between maximum photosynthetic assimilation and resistance of photosynthesis to drought. This response will be most detrimental to the carbon balance of piñon under predicted increases in aridity in the southwestern USA. © 2013 John Wiley & Sons Ltd.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2265468','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2265468"><span>A Continuum Model for Metabolic <span class="hlt">Gas</span> <span class="hlt">Exchange</span> in Pear Fruit</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ho, Q. Tri; Verboven, Pieter; Verlinden, Bert E.; Lammertyn, Jeroen; Vandewalle, Stefan; Nicolaï, Bart M.</p> <p>2008-01-01</p> <p><span class="hlt">Exchange</span> of O2 and CO2 of plants with their environment is essential for metabolic processes such as photosynthesis and respiration. In some fruits such as pears, which are typically stored under a controlled atmosphere with reduced O2 and increased CO2 levels to extend their commercial storage life, anoxia may occur, eventually leading to physiological disorders. In this manuscript we have developed a mathematical model to predict the internal <span class="hlt">gas</span> concentrations, including permeation, diffusion, and respiration and fermentation kinetics. Pear fruit has been selected as a case study. The model has been used to perform in silico experiments to evaluate the effect of, for example, fruit size or ambient <span class="hlt">gas</span> concentration on internal O2 and CO2 levels. The model incorporates the actual shape of the fruit and was solved using fluid dynamics software. Environmental conditions such as temperature and <span class="hlt">gas</span> composition have a large effect on the internal distribution of oxygen and carbon dioxide in fruit. Also, the fruit size has a considerable effect on local metabolic <span class="hlt">gas</span> concentrations; hence, depending on the size, local anaerobic conditions may result, which eventually may lead to physiological disorders. The model developed in this manuscript is to our knowledge the most comprehensive model to date to simulate <span class="hlt">gas</span> <span class="hlt">exchange</span> in plant tissue. It can be used to evaluate the effect of environmental stresses on fruit via in silico experiments and may lead to commercial applications involving long-term storage of fruit under controlled atmospheres. PMID:18369422</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29375728','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29375728"><span>Steel reinforced composite silicone membranes and its integration to microfluidic oxygenators for high performance <span class="hlt">gas</span> <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Matharoo, Harpreet; Dabaghi, Mohammadhossein; Rochow, Niels; Fusch, Gerhard; Saraei, Neda; Tauhiduzzaman, Mohammed; Veldhuis, Stephen; Brash, John; Fusch, Christoph; Selvaganapathy, P Ravi</p> <p>2018-01-01</p> <p>Respiratory distress syndrome (RDS) is one of the main causes of fatality in newborn infants, particularly in neonates with low birth-weight. Commercial extracorporeal oxygenators have been used for low-birth-weight neonates in neonatal intensive care units. However, these oxygenators require high blood volumes to prime. In the last decade, microfluidics oxygenators using enriched oxygen have been developed for this purpose. Some of these oxygenators use thin polydimethylsiloxane (PDMS) membranes to facilitate <span class="hlt">gas</span> <span class="hlt">exchange</span> between the blood flowing in the microchannels and the ambient air outside. However, PDMS is elastic and the thin membranes exhibit significant deformation and delamination under pressure which alters the architecture of the devices causing poor oxygenation or device failure. Therefore, an alternate membrane with high stability, low deformation under pressure, and high <span class="hlt">gas</span> <span class="hlt">exchange</span> was desired. In this paper, we present a novel composite membrane consisting of an ultra-thin stainless-steel mesh embedded in PDMS, designed specifically for a microfluidic single oxygenator unit (SOU). In comparison to homogeneous PDMS membranes, this composite membrane demonstrated high stability, low deformation under pressure, and high <span class="hlt">gas</span> <span class="hlt">exchange</span>. In addition, a new design for oxygenator with sloping profile and tapered inlet configuration has been introduced to achieve the same <span class="hlt">gas</span> <span class="hlt">exchange</span> at lower pressure drops. SOUs were tested by bovine blood to evaluate <span class="hlt">gas</span> <span class="hlt">exchange</span> properties. Among all tested SOUs, the flat design SOU with composite membrane has the highest oxygen <span class="hlt">exchange</span> of 40.32 ml/min m 2 . The superior performance of the new device with composite membrane was demonstrated by constructing a lung assist device (LAD) with a low priming volume of 10 ml. The LAD was achieved by the oxygen uptake of 0.48-0.90 ml/min and the CO 2 release of 1.05-2.27 ml/min at blood flow rates ranging between 8 and 48 ml/min. This LAD was shown to increase the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70040729','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70040729"><span>The impact of lower sea-ice extent on Arctic greenhouse-<span class="hlt">gas</span> <span class="hlt">exchange</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Parmentier, Frans-Jan W.; Christensen, Torben R.; Sørensen, Lise Lotte; Rysgaard, Søren; McGuire, A. David; Miller, Paul A.; Walker, Donald A.</p> <p>2013-01-01</p> <p>In September 2012, Arctic sea-ice extent plummeted to a new record low: two times lower than the 1979–2000 average. Often, record lows in sea-ice cover are hailed as an example of climate change impacts in the Arctic. Less apparent, however, are the implications of reduced sea-ice cover in the Arctic Ocean for marine–atmosphere CO2 <span class="hlt">exchange</span>. Sea-ice decline has been connected to increasing air temperatures at high latitudes. Temperature is a key controlling factor in the terrestrial <span class="hlt">exchange</span> of CO2 and methane, and therefore the greenhouse-<span class="hlt">gas</span> balance of the Arctic. Despite the large potential for feedbacks, many studies do not connect the diminishing sea-ice extent with changes in the interaction of the marine and terrestrial Arctic with the atmosphere. In this Review, we assess how current understanding of the Arctic Ocean and high-latitude ecosystems can be used to predict the impact of a lower sea-ice cover on Arctic greenhouse-<span class="hlt">gas</span> <span class="hlt">exchange</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860010453','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860010453"><span>Observations on <span class="hlt">gas</span> <span class="hlt">exchange</span> and element recycle within a <span class="hlt">gas</span>-closed algal-mouse system</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smernoff, D. T.; Wharton, R. A., Jr.; Averner, M. M.</p> <p>1986-01-01</p> <p>Life support systems based on bioregeneration rely on the control and manipulation of organisms. Algae are potentially useful for a variety of Closed Ecological Life Support System (CELSS) functions including the revitalization of atmospheres, production of food and for nitrogen fixation. The results of experiments conducted with a <span class="hlt">gas</span>-closed algal-mouse system designed to investigate <span class="hlt">gas</span> <span class="hlt">exchange</span> phenomena under varying algal environmental conditions, and the ability of algae to utilize oxidized mouse solid waste are reported. Inherent instabilities exist between the uptake and release of carbon dioxide (CO2) and oxygen (O2) by the mouse and algae in a <span class="hlt">gas</span>-closed system. Variations in light intensity and cell density alter the photosynthetic rate of the algae and enable short-term steady-state concentrations of atmospheric CO2 and O2. Different nitrogen sources (urea and nitrate) result in different algal assimilatory quotients (AQ). Combinations of photosynthetic rate and AQ ratio manipulations were examined for their potential in stabilizing atmospheric <span class="hlt">gas</span> concentrations in the <span class="hlt">gas</span>-closed algal-mouse system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70102289','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70102289"><span>Air-water <span class="hlt">gas</span> <span class="hlt">exchange</span> and CO2 flux in a mangrove-dominated estuary</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ho, David T.; Ferrón, Sara; Engel, Victor C.; Larsen, Laurel G.; Barr, Jordan G.</p> <p>2014-01-01</p> <p>Mangrove forests are highly productive ecosystems, but the fate of mangrove-derived carbon remains uncertain. Part of that uncertainty stems from the fact that <span class="hlt">gas</span> transfer velocities in mangrove-surrounded waters are not well determined, leading to uncertainty in air-water CO2 fluxes. Two SF6 tracer release experiments were conducted to determine <span class="hlt">gas</span> transfer velocities (k(600) = 8.3 ± 0.4 and 8.1 ± 0.6 cm h−1), along with simultaneous measurements of pCO2 to determine the air-water CO2 fluxes from Shark River, Florida (232.11 ± 23.69 and 171.13 ± 20.28 mmol C m−2 d−1), an estuary within the largest contiguous mangrove forest in North America. The <span class="hlt">gas</span> transfer velocity results are consistent with turbulent kinetic energy dissipation measurements, indicating a higher rate of turbulence and <span class="hlt">gas</span> <span class="hlt">exchange</span> than predicted by commonly used wind speed/<span class="hlt">gas</span> <span class="hlt">exchange</span> parameterizations. The results have important implications for carbon fluxes in mangrove ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1987JGR....92.1937J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987JGR....92.1937J"><span>On the parameters influencing air-water <span class="hlt">gas</span> <span class="hlt">exchange</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>JäHne, Bernd; Münnich, Karl Otto; BöSinger, Rainer; Dutzi, Alfred; Huber, Werner; Libner, Peter</p> <p>1987-02-01</p> <p>Detailed <span class="hlt">gas</span> <span class="hlt">exchange</span> measurements from two circular and one linear wind/wave tunnels are presented. Heat, He, CH4, CO2, Kr, and Xe have been used as tracers. The experiments show the central importance of waves for the water-side transfer process. With the onset of waves the Schmidt number dependence of the transfer velocity k changes from k ∝ Sc-⅔ to k ∝ Sc-½indicating a change in the boundary conditions at the surface. Moreover, energy put into the wave field by wind is transferred to near-surface turbulence enhancing <span class="hlt">gas</span> transfer. The data show that the mean square slope of the waves is the best parameter to characterize the free wavy surface with respect to water-side transfer processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000037970&hterms=gas+natural&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dgas%2Bnatural','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000037970&hterms=gas+natural&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dgas%2Bnatural"><span>The Effect of Rain on Air-Water <span class="hlt">Gas</span> <span class="hlt">Exchange</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ho, David T.; Bliven, Larry F.; Wanninkhof, Rik; Schlosser, Peter</p> <p>1997-01-01</p> <p>The relationship between <span class="hlt">gas</span> transfer velocity and rain rate was investigated at NASA's Rain-Sea Interaction Facility (RSIF) using several SF, evasion experiments. During each experiment, a water tank below the rain simulator was supersaturated with SF6, a synthetic <span class="hlt">gas</span>, and the <span class="hlt">gas</span> transfer velocities were calculated from the measured decrease in SF6 concentration with time. The results from experiments with IS different rain rates (7 to 10 mm/h) and 1 of 2 drop sizes (2.8 or 4.2 mm diameter) confirm a significant and systematic enhancement of air-water <span class="hlt">gas</span> <span class="hlt">exchange</span> by rainfall. The <span class="hlt">gas</span> transfer velocities derived from our experiment were related to the kinetic energy flux calculated from the rain rate and drop size. The relationship obtained for mono-dropsize rain at the RSIF was extrapolated to natural rain using the kinetic energy flux of natural rain calculated from the Marshall-Palmer raindrop size distribution. Results of laboratory experiments at RSIF were compared to field observations made during a tropical rainstorm in Miami, Florida and show good agreement between laboratory and field data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5899273','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5899273"><span>Potential for noninvasive assessment of lung inhomogeneity using highly precise, highly time-resolved measurements of <span class="hlt">gas</span> <span class="hlt">exchange</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Mountain, James E.; Santer, Peter; O’Neill, David P.; Smith, Nicholas M. J.; Ciaffoni, Luca; Couper, John H.; Ritchie, Grant A. D.; Hancock, Gus; Whiteley, Jonathan P.</p> <p>2018-01-01</p> <p>Inhomogeneity in the lung impairs <span class="hlt">gas</span> <span class="hlt">exchange</span> and can be an early marker of lung disease. We hypothesized that highly precise measurements of <span class="hlt">gas</span> <span class="hlt">exchange</span> contain sufficient information to quantify many aspects of the inhomogeneity noninvasively. Our aim was to explore whether one parameterization of lung inhomogeneity could both fit such data and provide reliable parameter estimates. A mathematical model of <span class="hlt">gas</span> <span class="hlt">exchange</span> in an inhomogeneous lung was developed, containing inhomogeneity parameters for compliance, vascular conductance, and dead space, all relative to lung volume. Inputs were respiratory flow, cardiac output, and the inspiratory and pulmonary arterial <span class="hlt">gas</span> compositions. Outputs were expiratory and pulmonary venous <span class="hlt">gas</span> compositions. All values were specified every 10 ms. Some parameters were set to physiologically plausible values. To estimate the remaining unknown parameters and inputs, the model was embedded within a nonlinear estimation routine to minimize the deviations between model and data for CO2, O2, and N2 flows during expiration. Three groups, each of six individuals, were studied: young (20–30 yr); old (70–80 yr); and patients with mild to moderate chronic obstructive pulmonary disease (COPD). Each participant undertook a 15-min measurement protocol six times. For all parameters reflecting inhomogeneity, highly significant differences were found between the three participant groups (P < 0.001, ANOVA). Intraclass correlation coefficients were 0.96, 0.99, and 0.94 for the parameters reflecting inhomogeneity in deadspace, compliance, and vascular conductance, respectively. We conclude that, for the particular participants selected, highly repeatable estimates for parameters reflecting inhomogeneity could be obtained from noninvasive measurements of respiratory <span class="hlt">gas</span> <span class="hlt">exchange</span>. NEW & NOTEWORTHY This study describes a new method, based on highly precise measures of <span class="hlt">gas</span> <span class="hlt">exchange</span>, that quantifies three distributions that are intrinsic to the lung</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22469733-radiation-from-large-gas-volumes-heat-exchange-steam-boiler-furnaces','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22469733-radiation-from-large-gas-volumes-heat-exchange-steam-boiler-furnaces"><span>Radiation from Large <span class="hlt">Gas</span> Volumes and Heat <span class="hlt">Exchange</span> in Steam Boiler Furnaces</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Makarov, A. N., E-mail: tgtu-kafedra-ese@mail.ru</p> <p>2015-09-15</p> <p>Radiation from large cylindrical <span class="hlt">gas</span> volumes is studied as a means of simulating the flare in steam boiler furnaces. Calculations of heat <span class="hlt">exchange</span> in a furnace by the zonal method and by simulation of the flare with cylindrical <span class="hlt">gas</span> volumes are described. The latter method is more accurate and yields more reliable information on heat transfer processes taking place in furnaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28416704','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28416704"><span>Diurnal Variation in <span class="hlt">Gas</span> <span class="hlt">Exchange</span>: The Balance between Carbon Fixation and Water Loss.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Matthews, Jack S A; Vialet-Chabrand, Silvere R M; Lawson, Tracy</p> <p>2017-06-01</p> <p>Stomatal control of transpiration is critical for maintaining important processes, such as plant water status, leaf temperature, as well as permitting sufficient CO 2 diffusion into the leaf to maintain photosynthetic rates ( A ). Stomatal conductance often closely correlates with A and is thought to control the balance between water loss and carbon gain. It has been suggested that a mesophyll-driven signal coordinates A and stomatal conductance responses to maintain this relationship; however, the signal has yet to be fully elucidated. Despite this correlation under stable environmental conditions, the responses of both parameters vary spatially and temporally and are dependent on species, environment, and plant water status. Most current models neglect these aspects of <span class="hlt">gas</span> <span class="hlt">exchange</span>, although it is clear that they play a vital role in the balance of carbon fixation and water loss. Future efforts should consider the dynamic nature of whole-plant <span class="hlt">gas</span> <span class="hlt">exchange</span> and how it represents much more than the sum of its individual leaf-level components, and they should take into consideration the long-term effect on <span class="hlt">gas</span> <span class="hlt">exchange</span> over time. © 2017 American Society of Plant Biologists. All Rights Reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010004659','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010004659"><span>BOREAS TE-9 In Situ Diurnal <span class="hlt">Gas</span> <span class="hlt">Exchange</span> of NAS Boreal Forest Stands</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Margolis, Hank; Coyea, Marie; Dang, Qinglai</p> <p>2000-01-01</p> <p>The BOREAS TE-9 team collected several data sets related to chemical and photosynthetic properties of leaves in boreal forest tree species. The purpose of the BOREAS TE-09 study was threefold: 1) to provide in situ <span class="hlt">gas</span> <span class="hlt">exchange</span> data that will be used to validate models of photosynthetic responses to light, temperature, and carbon dioxide (CO2); 2) to compare the photosynthetic responses of different tree crown levels (upper and lower); and 3) to characterize the diurnal water potential curves for these sites to get an indication of the extent to which soil moisture supply to leaves might be limiting photosynthesis. The <span class="hlt">gas</span> <span class="hlt">exchange</span> data of the BOREAS NSA were collected to characterize diurnal <span class="hlt">gas</span> <span class="hlt">exchange</span> and water potential of two canopy levels of five boreal canopy cover types: young jack pine, old jack pine, old aspen, lowland old black spruce, and upland black spruce. These data were collected between 27-May-1994 and 17-Sep-1994. The data are provided in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28426140','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28426140"><span>Stomatal kinetics and photosynthetic <span class="hlt">gas</span> <span class="hlt">exchange</span> along a continuum of isohydric to anisohydric regulation of plant water status.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Meinzer, Frederick C; Smith, Duncan D; Woodruff, David R; Marias, Danielle E; McCulloh, Katherine A; Howard, Ava R; Magedman, Alicia L</p> <p>2017-08-01</p> <p>Species' differences in the stringency of stomatal control of plant water potential represent a continuum of isohydric to anisohydric behaviours. However, little is known about how quasi-steady-state stomatal regulation of water potential may relate to dynamic behaviour of stomata and photosynthetic <span class="hlt">gas</span> <span class="hlt">exchange</span> in species operating at different positions along this continuum. Here, we evaluated kinetics of light-induced stomatal opening, activation of photosynthesis and features of quasi-steady-state photosynthetic <span class="hlt">gas</span> <span class="hlt">exchange</span> in 10 woody species selected to represent different degrees of anisohydry. Based on a previously developed proxy for the degree of anisohydry, species' leaf water potentials at turgor loss, we found consistent trends in photosynthetic <span class="hlt">gas</span> <span class="hlt">exchange</span> traits across a spectrum of isohydry to anisohydry. More anisohydric species had faster kinetics of stomatal opening and activation of photosynthesis, and these kinetics were closely coordinated within species. Quasi-steady-state stomatal conductance and measures of photosynthetic capacity and performance were also greater in more anisohydric species. Intrinsic water-use efficiency estimated from leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and stable carbon isotope ratios was lowest in the most anisohydric species. In comparisons between <span class="hlt">gas</span> <span class="hlt">exchange</span> traits, species rankings were highly consistent, leading to species-independent scaling relationships over the range of isohydry to anisohydry observed. © 2017 John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23845983','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23845983"><span>Probing the regional distribution of pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> through single-breath <span class="hlt">gas</span>- and dissolved-phase 129Xe MR imaging.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kaushik, S Sivaram; Freeman, Matthew S; Cleveland, Zackary I; Davies, John; Stiles, Jane; Virgincar, Rohan S; Robertson, Scott H; He, Mu; Kelly, Kevin T; Foster, W Michael; McAdams, H Page; Driehuys, Bastiaan</p> <p>2013-09-01</p> <p>Although some central aspects of pulmonary function (ventilation and perfusion) are known to be heterogeneous, the distribution of diffusive <span class="hlt">gas</span> <span class="hlt">exchange</span> remains poorly characterized. A solution is offered by hyperpolarized 129Xe magnetic resonance (MR) imaging, because this <span class="hlt">gas</span> can be separately detected in the lung's air spaces and dissolved in its tissues. Early dissolved-phase 129Xe images exhibited intensity gradients that favored the dependent lung. To quantitatively corroborate this finding, we developed an interleaved, three-dimensional radial sequence to image the gaseous and dissolved 129Xe distributions in the same breath. These images were normalized and divided to calculate "129Xe <span class="hlt">gas</span>-transfer" maps. We hypothesized that, for healthy volunteers, 129Xe <span class="hlt">gas</span>-transfer maps would retain the previously observed posture-dependent gradients. This was tested in nine subjects: when the subjects were supine, 129Xe <span class="hlt">gas</span> transfer exhibited a posterior-anterior gradient of -2.00 ± 0.74%/cm; when the subjects were prone, the gradient reversed to 1.94 ± 1.14%/cm (P < 0.001). The 129Xe <span class="hlt">gas</span>-transfer maps also exhibited significant heterogeneity, as measured by the coefficient of variation, that correlated with subject total lung capacity (r = 0.77, P = 0.015). <span class="hlt">Gas</span>-transfer intensity varied nonmonotonically with slice position and increased in slices proximal to the main pulmonary arteries. Despite substantial heterogeneity, the mean <span class="hlt">gas</span> transfer for all subjects was 1.00 ± 0.01 while supine and 1.01 ± 0.01 while prone (P = 0.25), indicating good "matching" between <span class="hlt">gas</span>- and dissolved-phase distributions. This study demonstrates that single-breath <span class="hlt">gas</span>- and dissolved-phase 129Xe MR imaging yields 129Xe <span class="hlt">gas</span>-transfer maps that are sensitive to altered <span class="hlt">gas</span> <span class="hlt">exchange</span> caused by differences in lung inflation and posture.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010004226','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010004226"><span>BOREAS TE-11 Leaf <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Measurements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hall, Forrest G. (Editor); Papagno, Andrea (Editor); Saugier, Bernard; Pontailler, J. Y.</p> <p>2000-01-01</p> <p>The Boreal Ecosystem-Atmospheric Study (BOREAS) TE-11 (Terrestrial Ecology) team collected several data sets in support of its efforts to characterize and interpret information on the sap flow, <span class="hlt">gas</span> <span class="hlt">exchange</span>, and lichen photosynthesis of boreal vegetation and meteorological data of the area studied. This data set contains measurements of assimilation and transpiration conducted at the Old Jack Pine (OJP) site during the growing seasons of 1993 and 1994. The data are stored in ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4510840','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4510840"><span>Oxygen-limited thermal tolerance is seen in a plastron-breathing insect and can be induced in a bimodal <span class="hlt">gas</span> <span class="hlt">exchanger</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Verberk, Wilco C. E. P.; Bilton, David T.</p> <p>2015-01-01</p> <p>ABSTRACT Thermal tolerance has been hypothesized to result from a mismatch between oxygen supply and demand. However, the generality of this hypothesis has been challenged by studies on various animal groups, including air-breathing adult insects. Recently, comparisons across taxa have suggested that differences in <span class="hlt">gas</span> <span class="hlt">exchange</span> mechanisms could reconcile the discrepancies found in previous studies. Here, we test this suggestion by comparing the behaviour of related insect taxa with different <span class="hlt">gas</span> <span class="hlt">exchange</span> mechanisms, with and without access to air. We demonstrate oxygen-limited thermal tolerance in air-breathing adults of the plastron-<span class="hlt">exchanging</span> water bug Aphelocheirus aestivalis. Ilyocoris cimicoides, a related, bimodal <span class="hlt">gas</span> <span class="hlt">exchanger</span>, did not exhibit such oxygen-limited thermal tolerance and relied increasingly on aerial <span class="hlt">gas</span> <span class="hlt">exchange</span> with warming. Intriguingly, however, when denied access to air, oxygen-limited thermal tolerance could also be induced in this species. Patterns in oxygen-limited thermal tolerance were found to be consistent across life-history stages in these insects, with nymphs employing the same <span class="hlt">gas</span> <span class="hlt">exchange</span> mechanisms as adults. These results advance our understanding of oxygen limitation at high temperatures; differences in the degree of respiratory control appear to modulate the importance of oxygen in setting tolerance limits. PMID:25964420</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26214174','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26214174"><span>Effect of Sediment <span class="hlt">Gas</span> Voids and Ebullition on Benthic Solute <span class="hlt">Exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Flury, Sabine; Glud, Ronnie N; Premke, Katrin; McGinnis, Daniel F</p> <p>2015-09-01</p> <p>The presence of free <span class="hlt">gas</span> in sediments and ebullition events can enhance the pore water transport and solute <span class="hlt">exchange</span> across the sediment-water interface. However, we experimentally and theoretically document that the presence of free <span class="hlt">gas</span> in sediments can counteract this enhancement effect. The apparent diffusivities (Da) of Rhodamine WT and bromide in sediments containing 8-18% <span class="hlt">gas</span> (Da,YE) were suppressed by 7-39% compared to the control (no <span class="hlt">gas</span>) sediments (Da,C). The measured ratios of Da,YE:Da,C were well within the range of ratios predicted by a theoretical soil model for <span class="hlt">gas</span>-bearing soils. Whereas <span class="hlt">gas</span> voids in sediments reduce the Da for soluble species, they represent a shortcut for low-soluble species such as methane and oxygen. Therefore, the presence of even minor amounts of <span class="hlt">gas</span> can increase the fluxes of low-soluble species (i.e., gases) by several factors, while simultaneously suppressing fluxes of dissolved species.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19750027239&hterms=gas+solubility&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dgas%2Bsolubility','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19750027239&hterms=gas+solubility&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dgas%2Bsolubility"><span>Analysis of effect of the solubility on <span class="hlt">gas</span> <span class="hlt">exchange</span> in nonhomogeneous lungs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Colburn, W. E., Jr.; Evans, J. W.; West, J. B.</p> <p>1974-01-01</p> <p>A comparison is made of the <span class="hlt">gas</span> <span class="hlt">exchange</span> in nonhomogeneous lung models and in homogeneous lung models with the same total blood flow and ventilation. It is shown that the ratio of the rate of <span class="hlt">gas</span> transfer of the inhomogeneous lung model over the rate of <span class="hlt">gas</span> transfer of the homogeneous lung model as a function of <span class="hlt">gas</span> solubility always has the qualitative features for gases with linear dissociation curves. This ratio is 1 for a <span class="hlt">gas</span> with zero solubility and decreases to a single minimum. It subsequently rises to approach 1 as the solubility tends to infinity. The early portion of the graph of this function is convex, then after a single inflection point it is concave.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.711a2012N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.711a2012N"><span>Measuring <span class="hlt">gas</span> temperature during spin-<span class="hlt">exchange</span> optical pumping process</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Normand, E.; Jiang, C. Y.; Brown, D. R.; Robertson, L.; Crow, L.; Tong, X.</p> <p>2016-04-01</p> <p>The <span class="hlt">gas</span> temperature inside a Spin-<span class="hlt">Exchange</span> Optical Pumping (SEOP) laser-pumping polarized 3He cell has long been a mystery. Different experimental methods were employed to measure this temperature but all were based on either modelling or indirect measurement. To date there has not been any direct experimental measurement of this quantity. Here we present the first direct measurement using neutron transmission to accurately determine the number density of 3He, the temperature is obtained using the ideal <span class="hlt">gas</span> law. Our result showed a surprisingly high <span class="hlt">gas</span> temperature of 380°C, compared to the 245°C of the 3He cell wall temperature and 178°C of the optical pumping oven temperature. This experiment result may be used to further investigate the unsolved puzzle of the "X-factor" in the SEOP process which places an upper bound to the 3He polarization that can be achieved. Additional spin relaxation mechanisms might exist due to the high <span class="hlt">gas</span> temperature, which could explain the origin of the X-factor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.4983F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.4983F"><span>Greenhouse <span class="hlt">gas</span> <span class="hlt">exchange</span> over grazed systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Felber, R.; Ammann, C.; Neftel, A.</p> <p>2012-04-01</p> <p>Grasslands act as sinks and sources of greenhouse gases (GHG) and are, in conjunction with livestock production systems, responsible for a large share of GHG emissions. Whereas ecosystem scale flux measurements (eddy covariance) are commonly used to investigate CO2 <span class="hlt">exchange</span> (and is becoming state-of-the-art for other GHGs, too), GHG emissions from agricultural animals are usually investigated on the scale of individual animals. Therefore eddy covariance technique has to be tested for combined systems (i.e. grazed systems). Our project investigates the ability of field scale flux measurements to reliably quantify the contribution of grazing dairy cows to the net <span class="hlt">exchange</span> of CO2 and CH4. To quantify the contribution of the animals to the net flux the position, movement, and grazing/rumination activity of each cow are recorded. In combination with a detailed footprint analysis of the eddy covariance fluxes, the animal related CO2 and CH4 emissions are derived and compared to standard emission values derived from respiration chambers. The aim of the project is to test the assumption whether field scale CO2 flux measurements adequately include the respiration of grazing cows and to identify potential errors in ecosystem Greenhouse <span class="hlt">gas</span> budgets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1050299','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1050299"><span>PREDICTION OF TOTAL DISSOLVED <span class="hlt">GAS</span> <span class="hlt">EXCHANGE</span> AT HYDROPOWER DAMS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Hadjerioua, Boualem; Pasha, MD Fayzul K; Stewart, Kevin M</p> <p>2012-07-01</p> <p>Total dissolved <span class="hlt">gas</span> (TDG) supersaturation in waters released at hydropower dams can cause <span class="hlt">gas</span> bubble trauma in fisheries resulting in physical injuries and eyeball protrusion that can lead to mortality. Elevated TDG pressures in hydropower releases are generally caused by the entrainment of air in spillway releases and the subsequent <span class="hlt">exchange</span> of atmospheric gasses into solution during passage through the stilling basin. The network of dams throughout the Columbia River Basin (CRB) are managed for irrigation, hydropower production, flood control, navigation, and fish passage that frequently result in both voluntary and involuntary spillway releases. These dam operations are constrained bymore » state and federal water quality standards for TDG saturation which balance the benefits of spillway operations designed for Endangered Species Act (ESA)-listed fisheries versus the degradation to water quality as defined by TDG saturation. In the 1970s, the United States Environmental Protection Agency (USEPA), under the federal Clean Water Act (Section 303(d)), established a criterion not to exceed the TDG saturation level of 110% in order to protect freshwater and marine aquatic life. The states of Washington and Oregon have adopted special water quality standards for TDG saturation in the tailrace and forebays of hydropower facilities on the Columbia and Snake Rivers where spillway operations support fish passage objectives. The physical processes that affect TDG <span class="hlt">exchange</span> at hydropower facilities have been studied throughout the CRB in site-specific studies and routine water quality monitoring programs. These data have been used to quantify the relationship between project operations, structural properties, and TDG <span class="hlt">exchange</span>. These data have also been used to develop predictive models of TDG <span class="hlt">exchange</span> to support real-time TDG management decisions. These empirically based predictive models have been developed for specific projects and account for both the fate of spillway</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25964420','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25964420"><span>Oxygen-limited thermal tolerance is seen in a plastron-breathing insect and can be induced in a bimodal <span class="hlt">gas</span> <span class="hlt">exchanger</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Verberk, Wilco C E P; Bilton, David T</p> <p>2015-07-01</p> <p>Thermal tolerance has been hypothesized to result from a mismatch between oxygen supply and demand. However, the generality of this hypothesis has been challenged by studies on various animal groups, including air-breathing adult insects. Recently, comparisons across taxa have suggested that differences in <span class="hlt">gas</span> <span class="hlt">exchange</span> mechanisms could reconcile the discrepancies found in previous studies. Here, we test this suggestion by comparing the behaviour of related insect taxa with different <span class="hlt">gas</span> <span class="hlt">exchange</span> mechanisms, with and without access to air. We demonstrate oxygen-limited thermal tolerance in air-breathing adults of the plastron-<span class="hlt">exchanging</span> water bug Aphelocheirus aestivalis. Ilyocoris cimicoides, a related, bimodal <span class="hlt">gas</span> <span class="hlt">exchanger</span>, did not exhibit such oxygen-limited thermal tolerance and relied increasingly on aerial <span class="hlt">gas</span> <span class="hlt">exchange</span> with warming. Intriguingly, however, when denied access to air, oxygen-limited thermal tolerance could also be induced in this species. Patterns in oxygen-limited thermal tolerance were found to be consistent across life-history stages in these insects, with nymphs employing the same <span class="hlt">gas</span> <span class="hlt">exchange</span> mechanisms as adults. These results advance our understanding of oxygen limitation at high temperatures; differences in the degree of respiratory control appear to modulate the importance of oxygen in setting tolerance limits. © 2015. Published by The Company of Biologists Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29760574','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29760574"><span>Seasonal variations in body composition, maximal oxygen uptake, and <span class="hlt">gas</span> <span class="hlt">exchange</span> threshold in cross-country skiers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Polat, Metin; Korkmaz Eryılmaz, Selcen; Aydoğan, Sami</p> <p>2018-01-01</p> <p>In order to ensure that athletes achieve their highest performance levels during competitive seasons, monitoring their long-term performance data is crucial for understanding the impact of ongoing training programs and evaluating training strategies. The present study was thus designed to investigate the variations in body composition, maximal oxygen uptake (VO 2max ), and <span class="hlt">gas</span> <span class="hlt">exchange</span> threshold values of cross-country skiers across training phases throughout a season. In total, 15 athletes who participate in international cross-country ski competitions voluntarily took part in this study. The athletes underwent incremental treadmill running tests at 3 different time points over a period of 1 year. The first measurements were obtained in July, during the first preparation period; the second measurements were obtained in October, during the second preparation period; and the third measurements were obtained in February, during the competition period. Body weight, body mass index (BMI), body fat (%), as well as VO 2max values and <span class="hlt">gas</span> <span class="hlt">exchange</span> threshold, measured using V-slope method during the incremental running tests, were assessed at all 3 time points. The collected data were analyzed using SPSS 20 package software. Significant differences between the measurements were assessed using Friedman's twoway variance analysis with a post hoc option. The athletes' body weights and BMI measurements at the third point were significantly lower compared with the results of the second measurement ( p <0.001). Moreover, the incremental running test time was significantly higher at the third measurement, compared with both the first ( p <0.05) and the second ( p <0.01) measurements. Similarly, the running speed during the test was significantly higher at the third measurement time point compared with the first measurement time point ( p <0.05). Body fat (%), time to reach the <span class="hlt">gas</span> <span class="hlt">exchange</span> threshold, running speed at the <span class="hlt">gas</span> <span class="hlt">exchange</span> threshold, VO 2max , amount of oxygen consumed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25232199','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25232199"><span>Nesting behaviour influences species-specific <span class="hlt">gas</span> <span class="hlt">exchange</span> across avian eggshells.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Portugal, Steven J; Maurer, Golo; Thomas, Gavin H; Hauber, Mark E; Grim, Tomáš; Cassey, Phillip</p> <p>2014-09-15</p> <p>Carefully controlled <span class="hlt">gas</span> <span class="hlt">exchange</span> across the eggshell is essential for the development of the avian embryo. Water vapour conductance (G(H2O)) across the shell, typically measured as mass loss during incubation, has been demonstrated to optimally ensure the healthy development of the embryo while avoiding desiccation. Accordingly, eggs exposed to sub-optimal <span class="hlt">gas</span> <span class="hlt">exchange</span> have reduced hatching success. We tested the association between eggshell G(H2O) and putative life-history correlates of adult birds, ecological nest parameters and physical characteristics of the egg itself to investigate how variation in G(H2O) has evolved to maintain optimal water loss across a diverse set of nest environments. We measured <span class="hlt">gas</span> <span class="hlt">exchange</span> through eggshell fragments in 151 British breeding bird species and fitted phylogenetically controlled, general linear models to test the relationship between G(H2O) and potential predictor parameters of each species. Of our 17 life-history traits, only two were retained in the final model: wet-incubating parent and nest type. Eggs of species where the parent habitually returned to the nest with wet plumage had significantly higher G(H2O) than those of parents that returned to the nest with dry plumage. Eggs of species nesting in ground burrows, cliffs and arboreal cups had significantly higher G(H2O) than those of species nesting on the ground in open nests or cups, in tree cavities and in shallow arboreal nests. Phylogenetic signal (measured as Pagel's λ) was intermediate in magnitude, suggesting that differences observed in the G(H2O) are dependent upon a combination of shared ancestry and species-specific life history and ecological traits. Although these data are correlational by nature, they are consistent with the hypothesis that parents constrained to return to the nest with wet plumage will increase the humidity of the nest environment, and the eggs of these species have evolved a higher G(H2O) to overcome this constraint and still</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.B11K..06A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.B11K..06A"><span>Limitations on <span class="hlt">gas</span> <span class="hlt">exchange</span> recovery following natural drought in Californian oak woodlands.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ackerly, D.; Skelton, R. P.; Dawson, T.; Thompson, S.; Feng, X.; Weitz, A.; McLaughlin, B.</p> <p>2017-12-01</p> <p>Abstract Background/Question/Methods Drought can cause major damage to plant communities, but species damage thresholds and post-drought recovery of forest productivity are not yet predictable. We asked the question how should forest net primary productivity recover following exposure to severe drought? We used a natural drought period to investigate whether drought responses and post-drought recovery of canopy health could be predicted by properties of the water transport system. We aimed to test the hypothesis that recovery of <span class="hlt">gas</span> <span class="hlt">exchange</span> and canopy health would be most severely limited by xylem embolism in stems. To do this we monitored leaf level <span class="hlt">gas</span> <span class="hlt">exchange</span> and water status for multiple individuals of two deciduous and two evergreen species for four years spanning a severe drought event and following subsequent rehydration. Results/Discussion Severe drought caused major declines in leaf water potential, reduced stomatal conductance and assimilation rates and increased canopy bareness in our four canopy species. Water potential surpassed levels associated with incipient embolism in leaves of most trees. In contrast, due to hydraulic segmentation, water potential only rarely surpassed critical thresholds in the stems of the study trees. Individuals that surpassed critical thresholds of embolism in the stem displayed significant canopy dieback and mortality. Thus, recovery of plant <span class="hlt">gas</span> <span class="hlt">exchange</span> and canopy health was predicted by xylem safety margin in stems, but not leaves, providing strong support for stem cavitation vulnerability as an index of damage under natural drought conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040090386&hterms=water+gas+exchange&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwater%2Bgas%2Bexchange','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040090386&hterms=water+gas+exchange&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwater%2Bgas%2Bexchange"><span>Steady-state canopy <span class="hlt">gas</span> <span class="hlt">exchange</span>: system design and operation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bugbee, B.</p> <p>1992-01-01</p> <p>This paper describes the use of a commercial growth chamber for canopy photosynthesis, respiration, and transpiration measurements. The system was designed to measure transpiration via water vapor fluxes, and the importance of this measurement is discussed. Procedures for continuous measurement of root-zone respiration are described, and new data is presented to dispel myths about sources of water vapor interference in photosynthesis and in the measurement of CO2 by infrared <span class="hlt">gas</span> analysis. Mitchell (1992) has described the fundamentals of various approaches to measuring photosynthesis. Because our system evolved from experience with other types of single-leaf and canopy <span class="hlt">gas-exchange</span> systems, it is useful to review advantages and disadvantages of different systems as they apply to various research objectives.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22216034-toxicodynamics-rigid-polystyrene-microparticles-pulmonary-gas-exchange-mice-implications-microemboli-based-drug-delivery-systems','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22216034-toxicodynamics-rigid-polystyrene-microparticles-pulmonary-gas-exchange-mice-implications-microemboli-based-drug-delivery-systems"><span>Toxicodynamics of rigid polystyrene microparticles on pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> in mice: Implications for microemboli-based drug delivery systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Kutscher, H.L.; Gao, D.; Li, S.</p> <p></p> <p>The toxicodynamic relationship between the number and size of pulmonary microemboli resulting from uniformly sized, rigid polystyrene microparticles (MPs) administered intravenously and their potential effects on pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> were investigated. CD-1 male mice (6–8 weeks) were intravenously administered 10, 25 and 45 μm diameter MPs. Oxygen hemoglobin saturation in the blood (SpO{sub 2}) was measured non-invasively using a pulse oximeter while varying inhaled oxygen concentration (F{sub I}O{sub 2}). The resulting data were fit to a physiologically based non-linear mathematical model that estimates 2 parameters: ventilation–perfusion ratio (V{sub A}/Q) and shunt (percentage of deoxygenated blood returning to systemic circulation). Themore » number of MPs administered prior to a statistically significant reduction in normalized V{sub A}/Q was dependent on particle size. MP doses that resulted in a significant reduction in normalized V{sub A}/Q one day post-treatment were 4000, 40,000 and 550,000 MPs/g for 45, 25 and 10 μm MPs, respectively. The model estimated V{sub A}/Q and shunt returned to baseline levels 7 days post-treatment. Measuring SpO{sub 2} alone was not sufficient to observe changes in <span class="hlt">gas</span> <span class="hlt">exchange</span>; however, when combined with model-derived V{sub A}/Q and shunt early reversible toxicity from pulmonary microemboli was detected suggesting that the model and physical measurements are both required for assessing toxicity. Moreover, it appears that the MP load required to alter <span class="hlt">gas</span> <span class="hlt">exchange</span> in a mouse prior to lethality is significantly higher than the anticipated required MP dose for effective drug delivery. Overall, the current results indicate that the microemboli-based approach for targeted pulmonary drug delivery is potentially safe and should be further explored. -- Highlights: ► Murine pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> after microembolization was non-invasively studied. ► A physiologically based model quantified impairment of pulmonary <span class="hlt">gas</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.B11B0442B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.B11B0442B"><span>Regulation of leaf-<span class="hlt">gas</span> <span class="hlt">exchange</span> strategies of woody plants under elevated CO2</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Belmecheri, S.; Guerrieri, R.; Voelker, S.</p> <p>2016-12-01</p> <p>Estimates of vegetation water use efficiency (WUE) have increasingly been assessed using both eddy covariance and plant stable isotope techniques but these data have often lead to differing conclusions. Eddy covariance can provide forest ecosystem-level responses of coupled carbon and water <span class="hlt">exchanges</span> to recent global change phenomena. These direct observations, however, are generally less than one or two decades, thus documenting ecosystem-level responses at elevated [CO2] concentrations (350-400 ppm). Therefore, eddy covariance data cannot directly address plant physiological mechanisms and adaptation to climate variability and anthropogenic factors, e.g., increasing atmospheric [CO2]. By contrast, tree based carbon isotope approaches can retrospectively assess intrinsic WUE over long periods and have documented physiological responses to ambient atmospheric [CO2] (ca), which have often been contextualized within generalized strategies for stomatal regulation of leaf <span class="hlt">gas-exchange</span>. These include maintenance of a constant leaf internal [CO2] (ci), a constant drawdown in [CO2] (ca - ci), and a constant ci/ca . Tree carbon isotope studies, however, cannot account for changes in leaf area of individual trees or canopies, which makes scaling up a difficult task. The limitations of these different approaches to understanding how forest water use efficiency has been impacted by rising [CO2] has contributed to the uncertainty in global terrestrial carbon cycling and the "missing" terrestrial carbon sink. We examined stable C isotope ratios (d13C) from woody plants over a wide range of [CO2] (200-400 ppm) to test for patterns of ci-regulation in response to rising ca. The analyses are not consistent with any of the leaf <span class="hlt">gas-exchange</span> regulation strategies noted above. The data suggest that ca - ci is still recently increasing in most species but that the rate of increase is less than expected from paleo trees which grew at much lower [CO2]. This evidence demonstrates that a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/21073780-fouling-reduction-characteristics-distributor-fluidized-bed-heat-exchanger-flue-gas-heat-recovery','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/21073780-fouling-reduction-characteristics-distributor-fluidized-bed-heat-exchanger-flue-gas-heat-recovery"><span>Fouling reduction characteristics of a no-distributor-fluidized-bed heat <span class="hlt">exchanger</span> for flue <span class="hlt">gas</span> heat recovery</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Jun, Y.D.; Lee, K.B.; Islam, S.Z.</p> <p>2008-07-01</p> <p>In conventional flue <span class="hlt">gas</span> heat recovery systems, the fouling by fly ashes and the related problems such as corrosion and cleaning are known to be major drawbacks. To overcome these problems, a single-riser no-distributor-fluidized-bed heat <span class="hlt">exchanger</span> is devised and studied. Fouling and cleaning tests are performed for a uniquely designed fluidized bed-type heat <span class="hlt">exchanger</span> to demonstrate the effect of particles on the fouling reduction and heat transfer enhancement. The tested heat <span class="hlt">exchanger</span> model (1 m high and 54 mm internal diameter) is a <span class="hlt">gas</span>-to-water type and composed of a main vertical tube and four auxiliary tubes through which particles circulatemore » and transfer heat. Through the present study, the fouling on the heat transfer surface could successfully be simulated by controlling air-to-fuel ratios rather than introducing particles through an external feeder, which produced soft deposit layers with 1 to 1.5 mm thickness on the inside pipe wall. Flue <span class="hlt">gas</span> temperature at the inlet of heat <span class="hlt">exchanger</span> was maintained at 450{sup o}C at the <span class="hlt">gas</span> volume rate of 0.738 to 0.768 CMM (0.0123 to 0.0128 m{sup 3}/sec). From the analyses of the measured data, heat transfer performances of the heat <span class="hlt">exchanger</span> before and after fouling and with and without particles were evaluated. Results showed that soft deposits were easily removed by introducing glass bead particles, and also heat transfer performance increased two times by the particle circulation. In addition, it was found that this type of heat <span class="hlt">exchanger</span> had high potential to recover heat of waste gases from furnaces, boilers, and incinerators effectively and to reduce fouling related problems.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.H53A1376G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.H53A1376G"><span>The Effect of Thermal Convection on Earth-Atmosphere CO2 <span class="hlt">Gas</span> <span class="hlt">Exchange</span> in Aggregated Soil</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ganot, Y.; Weisbrod, N.; Dragila, M. I.</p> <p>2011-12-01</p> <p><span class="hlt">Gas</span> transport in soils and surface-atmosphere <span class="hlt">gas</span> <span class="hlt">exchange</span> are important processes that affect different aspects of soil science such as soil aeration, nutrient bio-availability, sorption kinetics, soil and groundwater pollution and soil remediation. Diffusion and convection are the two main mechanisms that affect <span class="hlt">gas</span> transport, fate and emissions in the soils and in the upper vadose zone. In this work we studied CO2 soil-atmosphere <span class="hlt">gas</span> <span class="hlt">exchange</span> under both day-time and night-time conditions, focusing on the impact of thermal convection (TCV) during the night. Experiments were performed in a climate-controlled laboratory. One meter long columns were packed with matrix of different grain size (sand, gravel and soil aggregates). Air with 2000 ppm CO2 was injected into the bottom of the columns and CO2 concentration within the columns was continuously monitored by an Infra Red <span class="hlt">Gas</span> Analyzer. Two scenarios were compared for each soil: (1) isothermal conditions, representing day time conditions; and (2) thermal gradient conditions, i.e., atmosphere colder than the soil, representing night time conditions. Our results show that under isothermal conditions, diffusion is the major mechanism for surface-atmosphere <span class="hlt">gas</span> <span class="hlt">exchange</span> for all grain sizes; while under night time conditions the prevailing mechanism is dependent on the air permeability of the matrix: for sand and gravel it is diffusion, and for soil aggregates it is TCV. Calculated CO2 flux for the soil aggregates column shows that the TCV flux was three orders of magnitude higher than the diffusive flux.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29238999','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29238999"><span>Physiological <span class="hlt">gas</span> <span class="hlt">exchange</span> mapping of hyperpolarized 129 Xe using spiral-IDEAL and MOXE in a model of regional radiation-induced lung injury.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zanette, Brandon; Stirrat, Elaine; Jelveh, Salomeh; Hope, Andrew; Santyr, Giles</p> <p>2018-02-01</p> <p>To map physiological <span class="hlt">gas</span> <span class="hlt">exchange</span> parameters using dissolved hyperpolarized (HP) 129 Xe in a rat model of regional radiation-induced lung injury (RILI) with spiral-IDEAL and the model of xenon <span class="hlt">exchange</span> (MOXE). Results are compared to quantitative histology of pulmonary tissue and red blood cell (RBC) distribution. Two cohorts (n = 6 each) of age-matched rats were used. One was irradiated in the right-medial lung, producing regional injury. <span class="hlt">Gas</span> <span class="hlt">exchange</span> was mapped 4 weeks postirradiation by imaging dissolved-phase HP 129 Xe using spiral-IDEAL at five <span class="hlt">gas</span> <span class="hlt">exchange</span> timepoints using a clinical 1.5 T scanner. Physiological lung parameters were extracted regionally on a voxel-wise basis using MOXE. Mean <span class="hlt">gas</span> <span class="hlt">exchange</span> parameters, specifically air-capillary barrier thickness (δ) and hematocrit (HCT) in the right-medial lung were compared to the contralateral lung as well as nonirradiated control animals. Whole-lung spectroscopic analysis of <span class="hlt">gas</span> <span class="hlt">exchange</span> was also performed. δ was significantly increased (1.43 ± 0.12 μm from 1.07 ± 0.09 μm) and HCT was significantly decreased (17.2 ± 1.2% from 23.6 ± 1.9%) in the right-medial lung (i.e., irradiated region) compared to the contralateral lung of the irradiated rats. These changes were not observed in healthy controls. δ and HCT correlated with histologically measured increases in pulmonary tissue heterogeneity (r = 0.77) and decreases in RBC distribution (r = 0.91), respectively. No changes were observed using whole-lung analysis. This work demonstrates the feasibility of mapping <span class="hlt">gas</span> <span class="hlt">exchange</span> using HP 129 Xe in an animal model of RILI 4 weeks postirradiation. Spatially resolved <span class="hlt">gas</span> <span class="hlt">exchange</span> mapping is sensitive to regional injury between cohorts that was undetected with whole-lung <span class="hlt">gas</span> <span class="hlt">exchange</span> analysis, in agreement with histology. <span class="hlt">Gas</span> <span class="hlt">exchange</span> mapping holds promise for assessing regional lung function in RILI and other pulmonary diseases. © 2017 The Authors. Medical Physics published by Wiley</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018HMT....54..163S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018HMT....54..163S"><span>Influence of collector heat capacity and internal conditions of heat <span class="hlt">exchanger</span> on cool-down process of small <span class="hlt">gas</span> liquefier</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saberimoghaddam, Ali; Bahri Rasht Abadi, Mohammad Mahdi</p> <p>2018-01-01</p> <p>Joule-Thomson cooling systems are commonly used in <span class="hlt">gas</span> liquefaction. In small <span class="hlt">gas</span> liquefiers, transient cool-down time is high. Selecting suitable conditions for cooling down process leads to decrease in time and cost. In the present work, transient thermal behavior of Joule-Thomson cooling system including counter current helically coiled tube in tube heat <span class="hlt">exchanger</span>, expansion valve, and collector was studied using experimental tests and simulations. The experiments were performed using small <span class="hlt">gas</span> liquefier and nitrogen <span class="hlt">gas</span> as working fluid. The heat <span class="hlt">exchanger</span> was thermally studied by experimental data obtained from a small <span class="hlt">gas</span> liquefier. In addition, the simulations were performed using experimental data as variable boundary conditions. A comparison was done between presented and conventional methods. The effect of collector heat capacity and convection heat transfer coefficient inside the tubes on system performance was studied using temperature profiles along the heat <span class="hlt">exchanger</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18805813','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18805813"><span>Investigating onychophoran <span class="hlt">gas</span> <span class="hlt">exchange</span> and water balance as a means to inform current controversies in arthropod physiology.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Clusella-Trullas, Susana; Chown, Steven L</p> <p>2008-10-01</p> <p>Several controversies currently dominate the fields of arthropod metabolic rate, <span class="hlt">gas</span> <span class="hlt">exchange</span> and water balance, including the extent to which modulation of <span class="hlt">gas</span> <span class="hlt">exchange</span> reduces water loss, the origins of discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span>, the relationship between metabolic rate and life-history strategies, and the causes of Palaeozoic gigantism. In all of these areas, repeated calls have been made for the investigation of groups that might most inform the debates, especially of taxa in key phylogenetic positions. Here we respond to this call by investigating metabolic rate, respiratory water loss and critical oxygen partial pressure (Pc) in the onychophoran Peripatopsis capensis, a member of a group basal to the arthropods, and by synthesizing the available data on the Onychophora. The rate of carbon dioxide release (VCO2) at 20 degrees C in P. capensis is 0.043 ml CO2 h(-1), in keeping with other onychophoran species; suggesting that low metabolic rates in some arthropod groups are derived. Continuous <span class="hlt">gas</span> <span class="hlt">exchange</span> suggests that more complex <span class="hlt">gas</span> <span class="hlt">exchange</span> patterns are also derived. Total water loss in P. capensis is 57 mg H2O h(-1) at 20 degrees C, similar to modern estimates for another onychophoran species. High relative respiratory water loss rates ( approximately 34%; estimated using a regression technique) suggest that the basal condition in arthropods may be a high respiratory water loss rate. Relatively high Pc values (5-10% O2) suggest that substantial safety margins in insects are also a derived condition. Curling behaviour in P. capensis appears to be a strategy to lower energetic costs when resting, and the concomitant depression of water loss is a proximate consequence of this behaviour.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25944919','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25944919"><span>Interruption to cutaneous <span class="hlt">gas</span> <span class="hlt">exchange</span> is not a likely mechanism of WNS-associated death in bats.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Carey, Charleve S; Boyles, Justin G</p> <p>2015-07-01</p> <p>Pseudogymnoascus destructans is the causative fungal agent of white-nose syndrome (WNS), an emerging fungal-borne epizootic. WNS is responsible for a catastrophic decline of hibernating bats in North America, yet we have limited understanding of the physiological interactions between pathogen and host. Pseudogymnoascus destructans severely damages wings and tail membranes, by causing dryness that leads to whole sections crumbling off. Four possible mechanisms have been proposed by which infection could lead to dehydration; in this study, we tested one: P. destructans infection could cause disruption to passive <span class="hlt">gas-exchange</span> pathways across the wing membranes, thereby causing a compensatory increase in water-intensive pulmonary respiration. We hypothesized that total evaporative water loss would be greater when passive <span class="hlt">gas</span> <span class="hlt">exchange</span> was inhibited. We found that bats did not lose more water when passive pathways were blocked. This study provides evidence against the proposed proximal mechanism that disruption to passive <span class="hlt">gas</span> <span class="hlt">exchange</span> causes dehydration and death to WNS-infected bats. © 2015. Published by The Company of Biologists Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JCoPh.271..172N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JCoPh.271..172N"><span>Reprint of: A numerical modelling of <span class="hlt">gas</span> <span class="hlt">exchange</span> mechanisms between air and turbulent water with an aquarium chemical reaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nagaosa, Ryuichi S.</p> <p>2014-08-01</p> <p>This paper proposes a new numerical modelling to examine environmental chemodynamics of a gaseous material <span class="hlt">exchanged</span> between the air and turbulent water phases across a <span class="hlt">gas</span>-liquid interface, followed by an aquarium chemical reaction. This study uses an extended concept of a two-compartment model, and assumes two physicochemical substeps to approximate the <span class="hlt">gas</span> <span class="hlt">exchange</span> processes. The first substep is the <span class="hlt">gas</span>-liquid equilibrium between the air and water phases, A(g)⇌A(aq), with Henry's law constant H. The second is a first-order irreversible chemical reaction in turbulent water, A(aq)+H2O→B(aq)+H+ with a chemical reaction rate κA. A direct numerical simulation (DNS) technique has been employed to obtain details of the <span class="hlt">gas</span> <span class="hlt">exchange</span> mechanisms and the chemical reaction in the water compartment, while zero velocity and uniform concentration of A is considered in the air compartment. The study uses the different Schmidt numbers between 1 and 8, and six nondimensional chemical reaction rates between 10(≈0) to 101 at a fixed Reynolds number. It focuses on the effects of the Schmidt number and the chemical reaction rate on fundamental mechanisms of the <span class="hlt">gas</span> <span class="hlt">exchange</span> processes across the interface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70028198','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70028198"><span>Leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> characteristics of three neotropical mangrove species in response to varying hydroperiod</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Krauss, Ken W.; Twilley, Robert R.; Doyle, Thomas W.; Gardiner, Emile S.</p> <p>2006-01-01</p> <p>We determined how different hydroperiods affected leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> characteristics of greenhouse-grown seedlings (2002) and saplings (2003) of the mangrove species Avicennia germinans (L.) Stearn., Laguncularia racemosa (L.) Gaertn. f., and Rhizophora mangle L. Hydroperiod treatments included no flooding (unflooded), intermittent flooding (intermittent), and permanent flooding (flooded). Plants in the intermittent treatment were measured under both flooded and drained states and compared separately. In the greenhouse study, plants of all species maintained different leaf areas in the contrasting hydroperiods during both years. Assimilation–light response curves indicated that the different hydroperiods had little effect on leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> characteristics in either seedlings or saplings. However, short-term intermittent flooding for between 6 and 22 days caused a 20% reduction in maximum leaf-level carbon assimilation rate, a 51% lower light requirement to attain 50% of maximum assimilation, and a 38% higher demand from dark respiration. Although interspecific differences were evident for nearly all measured parameters in both years, there was little consistency in ranking of the interspecific responses. Species by hydroperiod interactions were significant only for sapling leaf area. In a field study, R. mangle saplings along the Shark River in the Everglades National Park either demonstrated no significant effect or slight enhancement of carbon assimilation and water-use efficiency while flooded. We obtained little evidence that contrasting hydroperiods affect leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> characteristics of mangrove seedlings or saplings over long time intervals; however, intermittent flooding may cause short-term depressions in leaf <span class="hlt">gas</span> <span class="hlt">exchange</span>. The resilience of mangrove systems to flooding, as demonstrated in the permanently flooded treatments, will likely promote photosynthetic and morphological adjustment to slight hydroperiod shifts in many settings..</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26991124','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26991124"><span>Optimal allocation of leaf epidermal area for <span class="hlt">gas</span> <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>de Boer, Hugo J; Price, Charles A; Wagner-Cremer, Friederike; Dekker, Stefan C; Franks, Peter J; Veneklaas, Erik J</p> <p>2016-06-01</p> <p>A long-standing research focus in phytology has been to understand how plants allocate leaf epidermal space to stomata in order to achieve an economic balance between the plant's carbon needs and water use. Here, we present a quantitative theoretical framework to predict allometric relationships between morphological stomatal traits in relation to leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and the required allocation of epidermal area to stomata. Our theoretical framework was derived from first principles of diffusion and geometry based on the hypothesis that selection for higher anatomical maximum stomatal conductance (gsmax ) involves a trade-off to minimize the fraction of the epidermis that is allocated to stomata. Predicted allometric relationships between stomatal traits were tested with a comprehensive compilation of published and unpublished data on 1057 species from all major clades. In support of our theoretical framework, stomatal traits of this phylogenetically diverse sample reflect spatially optimal allometry that minimizes investment in the allocation of epidermal area when plants evolve towards higher gsmax . Our results specifically highlight that the stomatal morphology of angiosperms evolved along spatially optimal allometric relationships. We propose that the resulting wide range of viable stomatal trait combinations equips angiosperms with developmental and evolutionary flexibility in leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> unrivalled by gymnosperms and pteridophytes. © 2016 The Authors New Phytologist © 2016 New Phytologist Trust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/867004','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/867004"><span>Corrosive resistant heat <span class="hlt">exchanger</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Richlen, Scott L.</p> <p>1989-01-01</p> <p>A corrosive and errosive resistant heat <span class="hlt">exchanger</span> which recovers heat from a contaminated heat stream. The heat <span class="hlt">exchanger</span> utilizes a boundary layer of innocuous <span class="hlt">gas</span>, which is continuously replenished, to protect the heat <span class="hlt">exchanger</span> surface from the hot contaminated <span class="hlt">gas</span>. The innocuous <span class="hlt">gas</span> is conveyed through ducts or perforations in the heat <span class="hlt">exchanger</span> wall. Heat from the heat stream is transferred by radiation to the heat <span class="hlt">exchanger</span> wall. Heat is removed from the outer heat <span class="hlt">exchanger</span> wall by a heat recovery medium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28667337','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28667337"><span>Contrasting dynamics of leaf potential and <span class="hlt">gas</span> <span class="hlt">exchange</span> during progressive drought cycles and recovery in Amorpha fruticosa and Robinia pseudoacacia.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yan, Weiming; Zheng, Shuxia; Zhong, Yangquanwei; Shangguan, Zhouping</p> <p>2017-06-30</p> <p>Leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> is closely associated with water relations; however, less attention has been given to this relationship over successive drought events. Dynamic changes in <span class="hlt">gas</span> <span class="hlt">exchange</span> and water potential in the seedlings of two woody species, Amorpha fruticosa and Robinia pseudoacacia, were monitored during recurrent drought. The pre-dawn leaf water potential declined in parallel with <span class="hlt">gas</span> <span class="hlt">exchange</span> in both species, and sharp declines in <span class="hlt">gas</span> <span class="hlt">exchange</span> occurred with decreasing water potential. A significant correlation between pre-dawn water potential and <span class="hlt">gas</span> <span class="hlt">exchange</span> was observed in both species and showed a right shift in R. pseudoacacia in the second drought. The results suggested that stomatal closure in early drought was mediated mainly by elevated foliar abscisic acid (ABA) in R. pseudoacacia, while a shift from ABA-regulated to leaf-water-potential-driven stomatal closure was observed in A. fruticosa. After re-watering, the pre-dawn water potential recovered quickly, whereas stomatal conductance did not fully recover from drought in R. pseudoacacia, which affected the ability to tightly control transpiration post-drought. The dynamics of recovery from drought suggest that stomatal behavior post-drought may be restricted mainly by hydraulic factors, but non-hydraulic factors may also be involved in R. pseudoacacia.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000JGR...105.8865H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000JGR...105.8865H"><span>Chamber measurement of surface-atmosphere trace <span class="hlt">gas</span> <span class="hlt">exchange</span>: Numerical evaluation of dependence on soil, interfacial layer, and source/sink properties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hutchinson, G. L.; Livingston, G. P.; Healy, R. W.; Striegl, R. G.</p> <p>2000-04-01</p> <p>We employed a three-dimensional finite difference <span class="hlt">gas</span> diffusion model to simulate the performance of chambers used to measure surface-atmosphere trace <span class="hlt">gas</span> <span class="hlt">exchange</span>. We found that systematic errors often result from conventional chamber design and deployment protocols, as well as key assumptions behind the estimation of trace <span class="hlt">gas</span> <span class="hlt">exchange</span> rates from observed concentration data. Specifically, our simulations showed that (1) when a chamber significantly alters atmospheric mixing processes operating near the soil surface, it also nearly instantaneously enhances or suppresses the postdeployment <span class="hlt">gas</span> <span class="hlt">exchange</span> rate, (2) any change resulting in greater soil <span class="hlt">gas</span> diffusivity, or greater partitioning of the diffusing <span class="hlt">gas</span> to solid or liquid soil fractions, increases the potential for chamber-induced measurement error, and (3) all such errors are independent of the magnitude, kinetics, and/or distribution of trace <span class="hlt">gas</span> sources, but greater for trace <span class="hlt">gas</span> sinks with the same initial absolute flux. Finally, and most importantly, we found that our results apply to steady state as well as non-steady-state chambers, because the slow rate of <span class="hlt">gas</span> diffusion in soil inhibits recovery of the former from their initial non-steady-state condition. Over a range of representative conditions, the error in steady state chamber estimates of the trace <span class="hlt">gas</span> flux varied from -30 to +32%, while estimates computed by linear regression from non-steady-state chamber concentrations were 2 to 31% too small. Although such errors are relatively small in comparison to the temporal and spatial variability characteristic of trace <span class="hlt">gas</span> <span class="hlt">exchange</span>, they bias the summary statistics for each experiment as well as larger scale trace <span class="hlt">gas</span> flux estimates based on them.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70185675','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70185675"><span>Chamber measurement of surface-atmosphere trace <span class="hlt">gas</span> <span class="hlt">exchange</span>--Numerical evaluation of dependence on soil interfacial layer, and source/sink products</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hutchinson, G.L.; Livingston, G.P.; Healy, R.W.; Striegl, Robert G.</p> <p>2000-01-01</p> <p>We employed a three-dimensional finite difference <span class="hlt">gas</span> diffusion model to simulate the performance of chambers used to measure surface-atmosphere tace <span class="hlt">gas</span> <span class="hlt">exchange</span>. We found that systematic errors often result from conventional chamber design and deployment protocols, as well as key assumptions behind the estimation of trace <span class="hlt">gas</span> <span class="hlt">exchange</span> rates from observed concentration data. Specifically, our simulationshowed that (1) when a chamber significantly alters atmospheric mixing processes operating near the soil surface, it also nearly instantaneously enhances or suppresses the postdeployment <span class="hlt">gas</span> <span class="hlt">exchange</span> rate, (2) any change resulting in greater soil <span class="hlt">gas</span> diffusivity, or greater partitioning of the diffusing <span class="hlt">gas</span> to solid or liquid soil fractions, increases the potential for chamber-induced measurement error, and (3) all such errors are independent of the magnitude, kinetics, and/or distribution of trace <span class="hlt">gas</span> sources, but greater for trace <span class="hlt">gas</span> sinks with the same initial absolute flux. Finally, and most importantly, we found that our results apply to steady state as well as non-steady-state chambers, because the slow rate of <span class="hlt">gas</span> diffusion in soil inhibits recovery of the former from their initial non-steady-state condition. Over a range of representative conditions, the error in steady state chamber estimates of the trace <span class="hlt">gas</span> flux varied from -30 to +32%, while estimates computed by linear regression from non-steadystate chamber concentrations were 2 to 31% too small. Although such errors are relatively small in comparison to the temporal and spatial variability characteristic of trace <span class="hlt">gas</span> <span class="hlt">exchange</span>, they bias the summary statistics for each experiment as well as larger scale trace <span class="hlt">gas</span> flux estimates based on them.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800023548','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800023548"><span>Changes in <span class="hlt">gas</span> <span class="hlt">exchange</span>, tissue respiration and glycolysis in rats during hypokinesia</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zorya, L. V.</p> <p>1980-01-01</p> <p>The results of an experiment which studied changes in oxygen balance under conditions of hypokinesia in rats is presented. The effect of the stress during hypokinesia is expressed most clearly in the changes of general <span class="hlt">gas</span> <span class="hlt">exchange</span>, and in the intensity of liver and myocardial tissue respiration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29351442','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29351442"><span>Measurements of pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> efficiency using expired <span class="hlt">gas</span> and oximetry: results in normal subjects.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>West, John B; Wang, Daniel L; Prisk, G Kim</p> <p>2018-04-01</p> <p>We are developing a novel, noninvasive method for measuring the efficiency of pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> in patients with lung disease. The patient wears an oximeter, and we measure the partial pressures of oxygen and carbon dioxide in inspired and expired <span class="hlt">gas</span> using miniature analyzers. The arterial Po 2 is then calculated from the oximeter reading and the oxygen dissociation curve, using the end-tidal Pco 2 to allow for the Bohr effect. This calculation is only accurate when the oxygen saturation is <94%, and therefore, these normal subjects breathed 12.5% oxygen. When the procedure is used in patients with hypoxemia, they breathe air. The Po 2 difference between the end-tidal and arterial values is called the "oxygen deficit." Preliminary data show that this index increases substantially in patients with lung disease. Here we report measurements of the oxygen deficit in 20 young normal subjects (age 19 to 31 yr) and 11 older normal subjects (47 to 88 yr). The mean value of the oxygen deficit in the young subjects was 2.02 ± 3.56 mmHg (means ± SD). This mean is remarkably small. The corresponding value in the older group was 7.53 ± 5.16 mmHg (means ± SD). The results are consistent with the age-related trend of the traditional alveolar-arterial difference, which is calculated from the calculated ideal alveolar Po 2 minus the measured arterial Po 2 . That measurement requires an arterial blood sample. The present study suggests that this noninvasive procedure will be valuable in assessing the degree of impaired <span class="hlt">gas</span> <span class="hlt">exchange</span> in patients with lung disease.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/5388528-conversion-deuterium-gas-heavy-water-catalytic-isotopic-exchange-using-wetproof-catalyst','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5388528-conversion-deuterium-gas-heavy-water-catalytic-isotopic-exchange-using-wetproof-catalyst"><span>Conversion of deuterium <span class="hlt">gas</span> to heavy water by catalytic isotopic <span class="hlt">exchange</span> using wetproof catalyst</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Quaiattini, R.J.; McGauley, M.P.; Burns, D.L.</p> <p></p> <p>The invention at Chalk River Nuclear Laboratories of a simple method of wetproofing platinum catalysts allows them to retain their activity in liquid water. High performance catalysts for the hydrogen-water isotope <span class="hlt">exchange</span> reaction that remain active for years can now be routinely produced. The first commercial application using the ordered-bed-type wetproofed isotope <span class="hlt">exchange</span> catalyst developed and patented by Atomic Energy of Canada Ltd. has been successfully completed. Approximately 9100 m/sup 3/ of deuterium <span class="hlt">gas</span> stored at Brookhaven National Laboratory was converted to high grade heavy water. Conversion efficiency exceeded 99.8%. The product D/sub 2/O concentration was 6.7 percentage points highermore » than the feed D/sub 2/ <span class="hlt">gas</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/4008424','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/4008424"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span> and lactate anaerobic thresholds: inter- and intraevaluator agreement.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gladden, L B; Yates, J W; Stremel, R W; Stamford, B A</p> <p>1985-06-01</p> <p>Twenty-four coded graph sets of <span class="hlt">gas</span> <span class="hlt">exchange</span> variables and blood lactate concentration (LA) plotted against time at 15-s intervals were analyzed by nine evaluators who determined the <span class="hlt">gas</span> <span class="hlt">exchange</span> (ATGE) and LA (ATLA) anaerobic thresholds. In addition, ATGE and ATLA were determined by a linear regression computer program. Agreement between ATGE and ATLA was poor; the median intraclass correlation coefficient (ri) was 0.53. Among evaluators, ATLA agreement (median ri = 0.81) was better than ATGE agreement (median ri = 0.70). In general, the ability of any evaluator to choose similar values from duplicate plots for either ATGE (median ri = 0.97) or ATLA (median ri = 0.995) was good. There was better agreement between the mean ATLA of the evaluators and the computer ATLA (ComLA) (ri = 0.88) than between the mean ATGE of the evaluators and the computer ATGE (ComVE), (ri = 0.58). Agreement between ComVE and ComLA was poor (ri = 0.29). These results suggest that ATGE does not accurately predict ATLA and that different evaluators choose different thresholds from the same data. Further assessment of the validity and precision of ATGE based on breath-by-breath and minute-by-minute data is needed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24970854','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24970854"><span>Pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> efficiency during exercise breathing normoxic and hypoxic <span class="hlt">gas</span> in adults born very preterm with low diffusion capacity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Duke, Joseph W; Elliott, Jonathan E; Laurie, Steven S; Beasley, Kara M; Mangum, Tyler S; Hawn, Jerold A; Gladstone, Igor M; Lovering, Andrew T</p> <p>2014-09-01</p> <p>Adults with a history of very preterm birth (<32 wk gestational age; PRET) have reduced lung function and significantly lower lung diffusion capacity for carbon monoxide (DLCO) relative to individuals born at term (CONT). Low DLCO may predispose PRET to diffusion limitation during exercise, particularly while breathing hypoxic <span class="hlt">gas</span> because of a reduced O2 driving gradient and pulmonary capillary transit time. We hypothesized that PRET would have significantly worse pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> efficiency [i.e., increased alveolar-to-arterial Po2 difference (AaDO2)] during exercise breathing room air or hypoxic <span class="hlt">gas</span> (FiO2 = 0.12) compared with CONT. To test this hypothesis, we compared the AaDO2 in PRET (n = 13) with a clinically mild reduction in DLCO (72 ± 7% of predicted) and CONT (n = 14) with normal DLCO (105 ± 10% of predicted) pre- and during exercise breathing room air and hypoxic <span class="hlt">gas</span>. Measurements of temperature-corrected arterial blood gases, and direct measure of O2 saturation (SaO2), were made prior to and during exercise at 25, 50, and 75% of peak oxygen consumption (V̇o2peak) while breathing room air and hypoxic <span class="hlt">gas</span>. In addition to DLCO, pulmonary function and exercise capacity were significantly less in PRET. Despite PRET having low DLCO, no differences were observed in the AaDO2 or SaO2 pre- or during exercise breathing room air or hypoxic <span class="hlt">gas</span> compared with CONT. Although our findings were unexpected, we conclude that reduced pulmonary function and low DLCO resulting from very preterm birth does not cause a measureable reduction in pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> efficiency. Copyright © 2014 the American Physiological Society.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26538177','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26538177"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span> and dive characteristics of the free-swimming backswimmer Anisops deanei.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jones, Karl K; Snelling, Edward P; Watson, Amy P; Seymour, Roger S</p> <p>2015-11-01</p> <p>Many aquatic insects utilise air bubbles on the surface of their bodies to supply O2 while they dive. The bubbles can simply store O2, as in the case of an 'air store', or they can act as a physical '<span class="hlt">gas</span> gill', extracting O2 from the water. Backswimmers of the genus Anisops augment their air store with O2 from haemoglobin cells located in the abdomen. The O2 release from the haemoglobin helps stabilise bubble volume, enabling backswimmers to remain near neutrally buoyant for a period of the dive. It is generally assumed that the backswimmer air store does not act as a <span class="hlt">gas</span> gill and that <span class="hlt">gas</span> <span class="hlt">exchange</span> with the water is negligible. This study combines measurements of dive characteristics under different exotic gases (N2, He, SF6, CO) with mathematical modelling, to show that the air store of the backswimmer Anisops deanei does <span class="hlt">exchange</span> gases with the water. Our results indicate that approximately 20% of O2 consumed during a dive is obtained directly from the water. Oxygen from the water complements that released from the haemoglobin, extending the period of near-neutral buoyancy and increasing dive duration. © 2015. Published by The Company of Biologists Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhRvL.120n3601R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhRvL.120n3601R"><span>Localized Magnetic Moments with Tunable Spin <span class="hlt">Exchange</span> in a <span class="hlt">Gas</span> of Ultracold Fermions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Riegger, L.; Darkwah Oppong, N.; Höfer, M.; Fernandes, D. R.; Bloch, I.; Fölling, S.</p> <p>2018-04-01</p> <p>We report on the experimental realization of a state-dependent lattice for a two-orbital fermionic quantum <span class="hlt">gas</span> with strong interorbital spin <span class="hlt">exchange</span>. In our state-dependent lattice, the ground and metastable excited electronic states of 173Yb take the roles of itinerant and localized magnetic moments, respectively. Repulsive on-site interactions in conjunction with the tunnel mobility lead to spin <span class="hlt">exchange</span> between mobile and localized particles, modeling the coupling term in the well-known Kondo Hamiltonian. In addition, we find that this <span class="hlt">exchange</span> process can be tuned resonantly by varying the on-site confinement. We attribute this to a resonant coupling to center-of-mass excited bound states of one interorbital scattering channel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25962614','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25962614"><span>The effects of oxygen induced pulmonary vasoconstriction on bedside measurement of pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Weinreich, Ulla M; Thomsen, Lars P; Rees, Stephen E; Rasmussen, Bodil S</p> <p>2016-04-01</p> <p>In patients with respiratory failure measurements of pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> are of importance. The bedside automatic lung parameter estimator (ALPE) of pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> is based on changes in inspired oxygen (FiO2) assuming that these changes do not affect pulmonary circulation. This assumption is investigated in this study. Forty-two out of 65 patients undergoing coronary artery bypass grafting (CABG) had measurements of mean pulmonary arterial pressure (MPAP), cardiac output and pulmonary capillary wedge pressure thus enabling the calculation of pulmonary vascular resistance (PVR) at each FiO2 level. The research version of ALPE was used and FiO2 was step-wise reduced a median of 0.20 and ultimately returned towards baseline values, allowing 6-8 min' steady state period at each of 4-6 levels before recording the oxygen saturation (SpO2). FiO2 reduction led to median decrease in SpO2 from 99 to 92 %, an increase in MPAP of 4 mmHg and an increase in PVR of 36 dyn s cm(-5). Changes were immediately reversed on returning FiO2 towards baseline. In this study changes in MPAP and PVR are small and immediately reversible consistent with small changes in pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span>. This indicates that mild deoxygenation induced pulmonary vasoconstriction does not have significant influences on the ALPE parameters in patients after CABG.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/863101','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/863101"><span>Charge <span class="hlt">exchange</span> system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Anderson, Oscar A.</p> <p>1978-01-01</p> <p>An improved charge <span class="hlt">exchange</span> system for substantially reducing pumping requirements of excess <span class="hlt">gas</span> in a controlled thermonuclear reactor high energy neutral beam injector. The charge <span class="hlt">exchange</span> system utilizes a jet-type blanket which acts simultaneously as the charge <span class="hlt">exchange</span> medium and as a shield for reflecting excess <span class="hlt">gas</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1411867','SCIGOV-DOEDE'); return false;" href="https://www.osti.gov/servlets/purl/1411867"><span>CO2 response (ACi) <span class="hlt">gas</span> <span class="hlt">exchange</span>, calculated Vcmax & Jmax parameters, Feb2016-May2016, PA-SLZ, PA-PNM: Panama</span></a></p> <p><a target="_blank" href="http://www.osti.gov/dataexplorer">DOE Data Explorer</a></p> <p>Rogers, Alistair [Brookhaven National Lab; Serbin, Shawn [Brookhaven National Lab; Ely, Kim [Brookhaven National Lab; Wu, Jin [BNL; Wolfe, Brett [Smithsonian; Dickman, Turin [Los Alamos National Lab; Collins, Adam [Los Alamos National Lab; Detto, Matteo [Princeton; Grossiord, Charlotte [Los Alamos National Lab; McDowell, Nate [Los Alamos National Lab; Michaletz, Sean</p> <p>2017-01-01</p> <p>CO2 response (ACi) <span class="hlt">gas</span> <span class="hlt">exchange</span> measured on leaves collected from sunlit canopy trees on a monthly basis from Feb to May 2016 at SLZ and PNM. Dataset includes calculated Vcmax and Jmax parameters. This data was collected as part of the 2016 ENSO campaign. See related datasets (existing and future) for further sample details, leaf water potential, LMA, leaf spectra, other <span class="hlt">gas</span> <span class="hlt">exchange</span> and leaf chemistry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4737892','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4737892"><span>A Comparative Data-Based Modeling Study on Respiratory CO2 <span class="hlt">Gas</span> <span class="hlt">Exchange</span> during Mechanical Ventilation</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kim, Chang-Sei; Ansermino, J. Mark; Hahn, Jin-Oh</p> <p>2016-01-01</p> <p>The goal of this study is to derive a minimally complex but credible model of respiratory CO2 <span class="hlt">gas</span> <span class="hlt">exchange</span> that may be used in systematic design and pilot testing of closed-loop end-tidal CO2 controllers in mechanical ventilation. We first derived a candidate model that captures the essential mechanisms involved in the respiratory CO2 <span class="hlt">gas</span> <span class="hlt">exchange</span> process. Then, we simplified the candidate model to derive two lower-order candidate models. We compared these candidate models for predictive capability and reliability using experimental data collected from 25 pediatric subjects undergoing dynamically varying mechanical ventilation during surgical procedures. A two-compartment model equipped with transport delay to account for CO2 delivery between the lungs and the tissues showed modest but statistically significant improvement in predictive capability over the same model without transport delay. Aggregating the lungs and the tissues into a single compartment further degraded the predictive fidelity of the model. In addition, the model equipped with transport delay demonstrated superior reliability to the one without transport delay. Further, the respiratory parameters derived from the model equipped with transport delay, but not the one without transport delay, were physiologically plausible. The results suggest that <span class="hlt">gas</span> transport between the lungs and the tissues must be taken into account to accurately reproduce the respiratory CO2 <span class="hlt">gas</span> <span class="hlt">exchange</span> process under conditions of wide-ranging and dynamically varying mechanical ventilation conditions. PMID:26870728</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=298042','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=298042"><span>Field Evaluation of Open System Chambers for Measuring Whole Canopy <span class="hlt">Gas</span> <span class="hlt">Exchanges</span></span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>The ability to monitor whole canopy CO2 and H2O fluxes of crop plants in the field is needed for many research efforts ranging from plant breeding to the study of Climate Change effects on crops. Four portable, transparent, open system chambers for measuring canopy <span class="hlt">gas</span> <span class="hlt">exchanges</span> were field tested on...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013BGeo...10.1379C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013BGeo...10.1379C"><span>Technical Note: A simple method for air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> measurements in mesocosms and its application in carbon budgeting</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Czerny, J.; Schulz, K. G.; Ludwig, A.; Riebesell, U.</p> <p>2013-03-01</p> <p>Mesocosms as large experimental units provide the opportunity to perform elemental mass balance calculations, e.g. to derive net biological turnover rates. However, the system is in most cases not closed at the water surface and gases <span class="hlt">exchange</span> with the atmosphere. Previous attempts to budget carbon pools in mesocosms relied on educated guesses concerning the <span class="hlt">exchange</span> of CO2 with the atmosphere. Here, we present a simple method for precise determination of air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> in mesocosms using N2O as a deliberate tracer. Beside the application for carbon budgeting, transfer velocities can be used to calculate <span class="hlt">exchange</span> rates of any <span class="hlt">gas</span> of known concentration, e.g. to calculate aquatic production rates of climate relevant trace gases. Using an arctic KOSMOS (Kiel Off Shore Mesocosms for future Ocean Simulation) experiment as an exemplary dataset, it is shown that the presented method improves accuracy of carbon budget estimates substantially. Methodology of manipulation, measurement, data processing and conversion to CO2 fluxes are explained. A theoretical discussion of prerequisites for precise <span class="hlt">gas</span> <span class="hlt">exchange</span> measurements provides a guideline for the applicability of the method under various experimental conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6562578','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/6562578"><span>A corrosive resistant heat <span class="hlt">exchanger</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Richlen, S.L.</p> <p>1987-08-10</p> <p>A corrosive and erosive resistant heat <span class="hlt">exchanger</span> which recovers heat from a contaminated heat stream. The heat <span class="hlt">exchanger</span> utilizes a boundary layer of innocuous <span class="hlt">gas</span>, which is continuously replenished, to protect the heat <span class="hlt">exchanger</span> surface from the hot contaminated <span class="hlt">gas</span>. The innocuous <span class="hlt">gas</span> is pumped through ducts or perforations in the heat <span class="hlt">exchanger</span> wall. Heat from the heat stream is transferred by radiation to the heat <span class="hlt">exchanger</span> wall. Heat is removed from the outer heat <span class="hlt">exchanger</span> wall by a heat recovery medium. 3 figs., 3 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=315495','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=315495"><span>Deficit irrigation: Arriving at the crop water stress index via <span class="hlt">gas</span> <span class="hlt">exchange</span> measurements</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Plant <span class="hlt">gas</span> <span class="hlt">exchange</span> provides a highly sensitive measure of the degree of drought stress. Canopy temperature (Tc) provides a much easier to acquire indication of crop water deficit that has been used in irrigation scheduling systems, but interpretation of this measurement has proven difficult. Our goa...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/25332','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/25332"><span>Leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> characteristics of three neotropical mangrove species in response to varying hydroperiod</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Ken W. Krauss; Robert R. Twilley; Thomas w. Doyle; Emile S. Gardiner</p> <p>2006-01-01</p> <p>We determined how different hydroperiods affected leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> characteristics of greenhouse-grown seedlings (2002) and saplings (2003) of the mangrove species Avicennia germinans (L.) Stearn., Laguncularia racemosa (L.) Gaertn. f., and Rhizophora mangle L. Hydroperiod treatments included...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRD..122.7664L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRD..122.7664L"><span>Atmospheric deposition and air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> fluxes of DDT and HCH in the Yangtze River Estuary, East China Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Zhongxia; Lin, Tian; Li, Yuanyuan; Jiang, Yuqing; Guo, Zhigang</p> <p>2017-07-01</p> <p>The Yangtze River Estuary (YRE) is strongly influenced by the Yangtze River and lies on the pathway of the East Asian Monsoon. This study examined atmospheric deposition and air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> fluxes of dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) to determine whether the YRE is a sink or source of selected pesticides at the air-water interface under the influences of river input and atmospheric transport. The air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> of DDT was characterized by net volatilization with a marked difference in its fluxes between summer (140 ng/m2/d) and the other three seasons (12 ng/m2/d), possibly due to the high surface seawater temperatures and larger riverine input in summer. However, there was no obvious seasonal variation in the atmospheric HCH deposition, and the air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> reached equilibrium because of low HCH levels in the air and seawater after the long-term banning of HCH and the degradation. The <span class="hlt">gas</span> <span class="hlt">exchange</span> flux of HCH was comparable to the dry and wet deposition fluxes at the air-water interface. This suggests that the influences from the Yangtze River input and East Asian continental outflow on the fate of HCH in the YRE were limited. The <span class="hlt">gas</span> <span class="hlt">exchange</span> flux of DDT was about fivefold higher than the total dry and wet deposition fluxes. DDT residues in agricultural soil transported by enhanced riverine runoff were responsible for sustaining such a high net volatilization in summer. Moreover, our results indicated that there were fresh sources of DDT from the local environment to sustain net volatilization throughout the year.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.......178W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......178W"><span>Aqueous turbulence structure immediately adjacent to the air - water interface and interfacial <span class="hlt">gas</span> <span class="hlt">exchange</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Binbin</p> <p></p> <p>Air-sea interaction and the interfacial <span class="hlt">exchange</span> of <span class="hlt">gas</span> across the air-water interface are of great importance in coupled atmospheric-oceanic environmental systems. Aqueous turbulence structure immediately adjacent to the air-water interface is the combined result of wind, surface waves, currents and other environmental forces and plays a key role in energy budgets, <span class="hlt">gas</span> fluxes and hence the global climate system. However, the quantification of turbulence structure sufficiently close to the air-water interface is extremely difficult. The physical relationship between interfacial <span class="hlt">gas</span> <span class="hlt">exchange</span> and near surface turbulence remains insufficiently investigated. This dissertation aims to measure turbulence in situ in a complex environmental forcing system on Lake Michigan and to reveal the relationship between turbulent statistics and the CO2 flux across the air-water interface. The major objective of this dissertation is to investigate the physical control of the interfacial <span class="hlt">gas</span> <span class="hlt">exchange</span> and to provide a universal parameterization of <span class="hlt">gas</span> transfer velocity from environmental factors, as well as to propose a mechanistic model for the global CO2 flux that can be applied in three dimensional climate-ocean models. Firstly, this dissertation presents an advanced measurement instrument, an in situ free floating Particle Image Velocimetry (FPIV) system, designed and developed to investigate the small scale turbulence structure immediately below the air-water interface. Description of hardware components, design of the system, measurement theory, data analysis procedure and estimation of measurement error were provided. Secondly, with the FPIV system, statistics of small scale turbulence immediately below the air-water interface were investigated under a variety of environmental conditions. One dimensional wave-number spectrum and structure function sufficiently close to the water surface were examined. The vertical profiles of turbulent dissipation rate were intensively studied</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1214906-review-findings-ignik-sikumi-co2-ch4-gas-hydrate-exchange-field-trial','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1214906-review-findings-ignik-sikumi-co2-ch4-gas-hydrate-exchange-field-trial"><span>Review of the findings of the Ignik Sikumi CO2-CH4 <span class="hlt">gas</span> hydrate <span class="hlt">exchange</span> field trial</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Anderson, Brian J.; Boswell, Ray; Collett, Tim S.</p> <p></p> <p>The Ignik Sikumi <span class="hlt">Gas</span> Hydrate <span class="hlt">Exchange</span> Field Trial was conducted by ConocoPhillips in partnership with the U.S. Department of Energy, the Japan Oil, <span class="hlt">Gas</span>, and Metals National Corporation, and the U.S. Geological Survey within the Prudhoe Bay Unit on the Alaska North Slope (ANS) during 2011 and 2012. The 2011 field program included drilling the vertical test well and performing extensive wireline logging through a thick section of <span class="hlt">gas</span>-hydrate-bearing sand reservoirs that provided substantial new insight into the nature of ANS <span class="hlt">gas</span> hydrate occurrences. The 2012 field program involved an extended, scientific field trial conducted within a single vertical wellmore » (“huff-and-puff” design) through three primary operational phases: 1) injection of a gaseous phase mixture of CO2, N2, and chemical tracers; 2) flowback conducted at down-hole pressures above the stability threshold for native CH4-hydrate, and 3) extended (30-days) flowback at pressures below the stability threshold of native CH4-hydrate. Ignik Sikumi represents the first field investigation of <span class="hlt">gas</span> hydrate response to chemical injection, and the longest-duration field reservoir response experiment yet conducted. Full descriptions of the operations and data collected have been fully reported by ConocoPhillips and are available to the science community. The 2011 field program indicated the presence of free water within the <span class="hlt">gas</span> hydrate reservoir, a finding with significant implications to the design of the <span class="hlt">exchange</span> trial – most notably the use of a mixed <span class="hlt">gas</span> injectant. While this decision resulted in a complex chemical environment within the reservoir that greatly tests current experimental and modeling capabilities – without such a mixture, it is apparent that injection could not have been achieved. While interpretation of the field data are continuing, the primary scientific findings and implications of the program are: 1) <span class="hlt">gas</span> hydrate destabilizing is self-limiting, dispelling any notion of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28337628','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28337628"><span>Study of plasma off-<span class="hlt">gas</span> treatment from spent ion <span class="hlt">exchange</span> resin pyrolysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Castro, Hernán Ariel; Luca, Vittorio; Bianchi, Hugo Luis</p> <p>2017-03-23</p> <p>Polystyrene divinylbenzene-based ion <span class="hlt">exchange</span> resins are employed extensively within nuclear power plants (NPPs) and research reactors for purification and chemical control of the cooling water system. To maintain the highest possible water quality, the resins are regularly replaced as they become contaminated with a range of isotopes derived from compromised fuel elements as well as corrosion and activation products including 14 C, 60 Co, 90 Sr, 129 I, and 137 Cs. Such spent resins constitute a major proportion (in volume terms) of the solid radioactive waste generated by the nuclear industry. Several treatment and conditioning techniques have been developed with a view toward reducing the spent resin volume and generating a stable waste product suitable for long-term storage and disposal. Between them, pyrolysis emerges as an attractive option. Previous work of our group suggests that the pyrolysis treatment of the resins at low temperatures between 300 and 350 °C resulted in a stable waste product with a significant volume reduction (>50%) and characteristics suitable for long-term storage and/or disposal. However, another important issue to take into account is the complexity of the off-<span class="hlt">gas</span> generated during the process and the different technical alternatives for its conditioning. Ongoing work addresses the characterization of the ion <span class="hlt">exchange</span> resin treatment's off-<span class="hlt">gas</span>. Additionally, the application of plasma technology for the treatment of the off-<span class="hlt">gas</span> current was studied as an alternative to more conventional processes utilizing oil- or <span class="hlt">gas</span>-fired post-combustion chambers operating at temperatures in excess of 1000 °C. A laboratory-scale flow reactor, using inductively coupled plasma, operating under sub-atmospheric conditions was developed. Fundamental experiments using model compounds have been performed, demonstrating a high destruction and removal ratio (>99.99%) for different reaction media, at low reactor temperatures and moderate power consumption</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29575588','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29575588"><span>Exercise on-transition uncoupling of ventilatory, <span class="hlt">gas</span> <span class="hlt">exchange</span> and cardiac hemodynamic kinetics accompany pulmonary oxygen stores depletion to impact exercise intolerance in human heart failure.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Van Iterson, E H; Smith, J R; Olson, T P</p> <p>2018-03-25</p> <p>In contrast to knowledge that heart failure (HF) patients demonstrate peak exercise uncoupling across ventilation, <span class="hlt">gas</span> <span class="hlt">exchange</span> and cardiac haemodynamics, whether this dyssynchrony follows that at the exercise on-transition is unclear. This study tested whether exercise on-transition temporal lag for ventilation relative to <span class="hlt">gas</span> <span class="hlt">exchange</span> and oxygen pulse (O 2 pulse) couples with effects from <span class="hlt">abnormal</span> pulmonary gaseous oxygen store (O 2store ) contributions to V˙O 2 to interdependently precipitate persistently elevated ventilatory demand and low oxidative metabolic capacity in HF. Beat-to-beat HR and breath-to-breath ventilation and <span class="hlt">gas</span> <span class="hlt">exchange</span> were continuously acquired in HF (N = 9, ejection fraction = 30 ± 9%) and matched controls (N = 10) during square-wave ergometry at 60% V˙O 2peak (46 ± 14 vs 125 ± 54-W, P < .001). Temporal responses across V˙ E , V˙O 2 and O 2 pulse were assessed for the exercise on-transition using single exponential model Phase II on-kinetic time constants (τ = time to reach 63% steady-state rise). Breath-to-breath <span class="hlt">gas</span> fractions and respiratory flows were used to determine O 2stores . HF vs controls: τ for V˙ E (137 ± 93 vs 74 ± 40-seconds, P = .03), V˙O 2 (60 ± 40 vs 23 ± 5-seconds, P = .03) and O 2 pulse (28 ± 18 vs 23 ± 15-seconds, P = .59). Within HF, τ for V˙ E differed from O 2 pulse (P < .02), but not V˙O 2 . Exercise V˙ E rise (workload indexed) differed in HF vs controls (545 ± 139 vs 309 ± 88-mL min -1 W -1 , P < .001). Exercise on-transition O 2store depletion in HF exceeded controls, generally persisting to end-exercise. These data suggest HF demonstrated exercise on-transition O 2store depletion (high O 2store contribution to V˙O 2 ) coupled with dyssynchronous V˙ E , V˙O 2 and O 2 pulse kinetics-not attributable to prolonged cardiac haemodynamics. Persistent high ventilatory demand and low oxidative metabolic capacity in HF may be precipitated by physiological uncoupling occurring within the exercise</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880029838&hterms=Chlorella&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DChlorella','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880029838&hterms=Chlorella&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DChlorella"><span>Operation of an experimental algal <span class="hlt">gas</span> <span class="hlt">exchanger</span> for use in a CELSS</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smernoff, David T.; Wharton, Robert A., Jr.; Averner, Maurice M.</p> <p>1987-01-01</p> <p>Concepts of a CELSS anticipate the use of photosynthetic organisms for air revitalization. The rates of production and uptake of carbon dioxide and oxygen between the crew and the photosynthetic organisms are mismatched. An algal system used for <span class="hlt">gas</span> <span class="hlt">exchange</span> only will have the difficulty of an accumulation or depletion of these gases beyond physiologically tolerable limits. The results of a study designed to test the feasibility of using environmental manipulations to maintain physiologically appropriate atmospheres for algae (Chlorella pyrenoidosa) and mice (Mus musculus strain DW/J) in a <span class="hlt">gas</span>-closed system is reported. Specifically, the atmosphere behavior of this system with Chlorella grown on nitrate or urea and at different light intensities and optical densities is considered. Manipulation of both the photosynthetic rate and the assimilatory quotient of the alga has been found to reduce the mismatch of <span class="hlt">gas</span> requirements and allow operation of the system in a <span class="hlt">gas</span>-stable manner.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/32773','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/32773"><span>Comparative <span class="hlt">gas-exchange</span> in leaves of intact and clipped, natural and planted cherybark oak (Quercus pagoda Raf.) seedlings</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Brian R. Lockhart; John D. Hodges</p> <p>1994-01-01</p> <p><span class="hlt">Gas-exchange</span> measurements, including CO2-<span class="hlt">exchange</span> rate (net photosynthesis), stomatal conductance, and transpiration, were conducted on intact and clipped cherrybark oak (Quercus pagoda Raf.) seedlings growing inthe field and in a nursery bed. Seedlings inthe field, released frommidstory and understory woody competition, showed...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9874638','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9874638"><span>Oxygen isotope <span class="hlt">exchange</span> between refractory inclusion in Allende and solar nebula <span class="hlt">gas</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yurimoto, H; Ito, M; Nagasawa, H</p> <p>1998-12-04</p> <p>A calcium-aluminum-rich inclusion (CAI) from the Allende meteorite was analyzed and found to contain melilite crystals with extreme oxygen-isotope composition (approximately 5 percent oxygen-16 enrichment relative to terrestrial oxygen-16). Some of the melilite is also anomalously enriched in oxygen-16 compared with oxygen isotopes measured in other CAIs. The oxygen isotopic variation measured among the minerals (melilite, spinel, and fassaite) indicates that crystallization of the CAI started from oxygen-16-rich materials that were probably liquid droplets in the solar nebula, and oxygen isotope <span class="hlt">exchange</span> with the surrounding oxygen-16-poor nebular <span class="hlt">gas</span> progressed through the crystallization of the CAI. Additional oxygen isotope <span class="hlt">exchange</span> also occurred during subsequent reheating events in the solar nebula.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9836634','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9836634"><span>Oxygen isotope <span class="hlt">exchange</span> between refractory inclusion in allende and solar nebula <span class="hlt">Gas</span></span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yurimoto; Ito; Nagasawa</p> <p>1998-12-04</p> <p>A calcium-aluminum-rich inclusion (CAI) from the Allende meteorite was analyzed and found to contain melilite crystals with extreme oxygen-isotope compositions ( approximately 5 percent oxygen-16 enrichment relative to terrestrial oxygen-16). Some of the melilite is also anomalously enriched in oxygen-16 compared with oxygen isotopes measured in other CAIs. The oxygen isotopic variation measured among the minerals (melilite, spinel, and fassaite) indicates that crystallization of the CAI started from oxygen-16-rich materials that were probably liquid droplets in the solar nebula, and oxygen isotope <span class="hlt">exchange</span> with the surrounding oxygen-16-poor nebular <span class="hlt">gas</span> progressed through the crystallization of the CAI. Additional oxygen isotope <span class="hlt">exchange</span> also occurred during subsequent reheating events in the solar nebula.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27460608','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27460608"><span>Oxygen <span class="hlt">exchange</span> at <span class="hlt">gas</span>/oxide interfaces: how the apparent activation energy of the surface <span class="hlt">exchange</span> coefficient depends on the kinetic regime.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fielitz, Peter; Borchardt, Günter</p> <p>2016-08-10</p> <p>In the dedicated literature the oxygen surface <span class="hlt">exchange</span> coefficient KO and the equilibrium oxygen <span class="hlt">exchange</span> rate [Fraktur R] are considered to be directly proportional to each other regardless of the experimental circumstances. Recent experimental observations, however, contradict the consequences of this assumption. Most surprising is the finding that the apparent activation energy of KO depends dramatically on the kinetic regime in which it has been determined, i.e. surface <span class="hlt">exchange</span> controlled vs. mixed or diffusion controlled. This work demonstrates how the diffusion boundary condition at the <span class="hlt">gas</span>/solid interface inevitably entails a correlation between the oxygen surface <span class="hlt">exchange</span> coefficient KO and the oxygen self-diffusion coefficient DO in the bulk ("on top" of the correlation between KO and [Fraktur R] for the pure surface <span class="hlt">exchange</span> regime). The model can thus quantitatively explain the range of apparent activation energies measured in the different regimes: in the surface <span class="hlt">exchange</span> regime the apparent activation energy only contains the contribution of the equilibrium <span class="hlt">exchange</span> rate, whereas in the mixed or in the diffusion controlled regime the contribution of the oxygen self-diffusivity has also to be taken into account, which may yield significantly higher apparent activation energies and simultaneously quantifies the correlation KO ∝ DO(1/2) observed for a large number of oxides in the mixed or diffusion controlled regime, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25993893','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25993893"><span>Modelling non-steady-state isotope enrichment of leaf water in a <span class="hlt">gas-exchange</span> cuvette environment.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Song, Xin; Simonin, Kevin A; Loucos, Karen E; Barbour, Margaret M</p> <p>2015-12-01</p> <p>The combined use of a <span class="hlt">gas-exchange</span> system and laser-based isotope measurement is a tool of growing interest in plant ecophysiological studies, owing to its relevance for assessing isotopic variability in leaf water and/or transpiration under non-steady-state (NSS) conditions. However, the current Farquhar & Cernusak (F&C) NSS leaf water model, originally developed for open-field scenarios, is unsuited for use in a <span class="hlt">gas-exchange</span> cuvette environment where isotope composition of water vapour (δv ) is intrinsically linked to that of transpiration (δE ). Here, we modified the F&C model to make it directly compatible with the δv -δE dynamic characteristic of a typical cuvette setting. The resultant new model suggests a role of 'net-flux' (rather than 'gross-flux' as suggested by the original F&C model)-based leaf water turnover rate in controlling the time constant (τ) for the approach to steady sate. The validity of the new model was subsequently confirmed in a cuvette experiment involving cotton leaves, for which we demonstrated close agreement between τ values predicted from the model and those measured from NSS variations in isotope enrichment of transpiration. Hence, we recommend that our new model be incorporated into future isotope studies involving a cuvette condition where the transpiration flux directly influences δv . There is an increasing popularity among plant ecophysiologists to use a <span class="hlt">gas-exchange</span> system coupled to laser-based isotope measurement for investigating non-steady state (NSS) isotopic variability in leaf water (and/or transpiration); however, the current Farquhar & Cernusak (F&C) NSS leaf water model is unsuited for use in a <span class="hlt">gas-exchange</span> cuvette environment due to its implicit assumption of isotope composition of water vapor (δv ) being constant and independent of that of transpiration (δE ). In the present study, we modified the F&C model to make it compatible with the dynamic relationship between δv and δE as is typically associated</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23069190','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23069190"><span>Estimating oxygen diffusive conductances of <span class="hlt">gas-exchange</span> systems: A stereological approach illustrated with the human placenta.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mayhew, Terry M</p> <p>2014-01-01</p> <p>For many organisms, respiratory <span class="hlt">gas</span> <span class="hlt">exchange</span> is a vital activity and different types of <span class="hlt">gas-exchange</span> apparatus have evolved to meet individual needs. They include not only skin, gills, tracheal systems and lungs but also transient structures such as the chorioallantois of avian eggs and the placenta of eutherian mammals. The ability of these structures to allow passage of oxygen by passive diffusion can be expressed as a diffusive conductance (units: cm(3) O2 min(-1) kPa(-1)). Occasionally, the ability to estimate diffusive conductance by physiological techniques is compromised by the difficulty of obtaining O2 partial pressures on opposite sides of the tissue interface between the delivery medium (air, water, blood) and uptake medium (usually blood). An alternative strategy is to estimate a morphometric diffusive conductance by combining stereological estimates of key structural quantities (volumes, surface areas, membrane thicknesses) with complementary physicochemical data (O2-haemoglobin chemical reaction rates and Krogh's permeability coefficients). This approach has proved valuable in a variety of comparative studies on respiratory organs from diverse species. The underlying principles were formulated in pioneering studies on the pulmonary lung but are illustrated here by taking the human placenta as the <span class="hlt">gas</span> <span class="hlt">exchanger</span>. Copyright © 2012 Elsevier GmbH. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/25482','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/25482"><span>Comparative <span class="hlt">gas-exchange</span> in leaves of intact and clipped, natural and planted cherrybark oak (Quercus pagoda Raf.) seedlings</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Brian R. Lockhart; John D. Hodges</p> <p>2005-01-01</p> <p><span class="hlt">Gas-exchange</span> measurements, including C022-<span class="hlt">exchange</span> rate (net photosynthesis), stomatal conductance, and transpiration, were conducted on intact and clipped cherrybark oak (Quercus pagoda Raf.) seedlings growing in the field and in a nursery bed. Seedlings in the field, released from midstory and understory woody competition,...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20516484','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20516484"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span> and hydraulics in seedlings of Hevea brasiliensis during water stress and recovery.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chen, Jun-Wen; Zhang, Qiang; Li, Xiao-Shuang; Cao, Kun-Fang</p> <p>2010-07-01</p> <p>The response of plants to drought has received significant attention, but far less attention has been given to the dynamic response of plants during recovery from drought. Photosynthetic performance and hydraulic capacity were monitored in seedlings of Hevea brasiliensis under water stress and during recovery following rewatering. Leaf water relation, <span class="hlt">gas</span> <span class="hlt">exchange</span> rate and hydraulic conductivity decreased gradually after water stress fell below a threshold, whereas instantaneous water use efficiency and osmolytes increased significantly. After 5 days of rewatering, leaf water relation, maximum stomatal conductance (g(s-max)) and plant hydraulic conductivity had recovered to the control levels except for sapwood area-specific hydraulic conductivity, photosynthetic assimilation rate and osmolytes. During the phase of water stress, stomata were almost completely closed before water transport efficiency decreased substantially, and moreover, the leaf hydraulic pathway was more vulnerable to water stress-induced embolism than the stem hydraulic pathway. Meanwhile, g(s-max) was linearly correlated with hydraulic capacity when water stress exceeded a threshold. In addition, a positive relationship was shown to occur between the recovery of g(s-max) and of hydraulic capacity during the phase of rewatering. Our results suggest (i) that stomatal closure effectively reduces the risk of xylem dysfunction in water-stressed plants at the cost of <span class="hlt">gas</span> <span class="hlt">exchange</span>, (ii) that the leaf functions as a safety valve to protect the hydraulic pathway from water stress-induced dysfunction to a larger extent than does the stem and (iii) that the full drought recovery of <span class="hlt">gas</span> <span class="hlt">exchange</span> is restricted by not only hydraulic factors but also non-hydraulic factors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70185308','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70185308"><span>Numerical evaluation of static-chamber measurements of soil-atmospheric <span class="hlt">gas</span> <span class="hlt">exchange</span>--Identification of physical processes</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Healy, Richard W.; Striegl, Robert G.; Russell, Thomas F.; Hutchinson, Gordon L.; Livingston, Gerald P.</p> <p>1996-01-01</p> <p>The <span class="hlt">exchange</span> of gases between soil and atmosphere is an important process that affects atmospheric chemistry and therefore climate. The static-chamber method is the most commonly used technique for estimating the rate of that <span class="hlt">exchange</span>. We examined the method under hypothetical field conditions where diffusion was the only mechanism for <span class="hlt">gas</span> transport and the atmosphere outside the chamber was maintained at a fixed concentration. Analytical and numerical solutions to the soil <span class="hlt">gas</span> diffusion equation in one and three dimensions demonstrated that <span class="hlt">gas</span> flux density to a static chamber deployed on the soil surface was less in magnitude than the ambient <span class="hlt">exchange</span> rate in the absence of the chamber. This discrepancy, which increased with chamber deployment time and air-filled porosity of soil, is attributed to two physical factors: distortion of the soil <span class="hlt">gas</span> concentration gradient (the magnitude was decreased in the vertical component and increased in the radial component) and the slow transport rate of diffusion relative to mixing within the chamber. Instantaneous flux density to a chamber decreased continuously with time; steepest decreases occurred so quickly following deployment and in response to such slight changes in mean chamber headspace concentration that they would likely go undetected by most field procedures. Adverse influences of these factors were reduced by mixing the chamber headspace, minimizing deployment time, maximizing the height and radius of the chamber, and pushing the rim of the chamber into the soil. Nonlinear models were superior to a linear regression model for estimating flux densities from mean headspace concentrations, suggesting that linearity of headspace concentration with time was not necessarily a good indicator of measurement accuracy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910041723&hterms=water+gas+exchange&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwater%2Bgas%2Bexchange','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910041723&hterms=water+gas+exchange&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwater%2Bgas%2Bexchange"><span>Relationship between <span class="hlt">gas</span> <span class="hlt">exchange</span>, wind speed, and radar backscatter in a large wind-wave tank</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wanninkhof, Richard H.; Bliven, L. F.</p> <p>1991-01-01</p> <p>The relationships between the <span class="hlt">gas</span> <span class="hlt">exchange</span>, wind speed, friction velocity, and radar backscatter from the water surface was investigated using data obtained in a large water tank in the Delft (Netherlands) wind-wave tunnel, filled with water supersaturated with SF6, N2O, and CH4. Results indicate that the <span class="hlt">gas</span>-transfer velocities of these substances were related to the wind speed with a power law dependence. Microwave backscatter from water surface was found to be related to <span class="hlt">gas</span> transfer velocities by a relationship in the form k(<span class="hlt">gas</span>) = a 10 exp (b A0), where k is the <span class="hlt">gas</span> transfer velocity for the particular <span class="hlt">gas</span>, the values of a and b are obtained from a least squares fit of the average backscatter cross section and <span class="hlt">gas</span> transfer at 80 m, and A0 is the directional (azimuthal) averaged return.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920071656&hterms=biomass+production&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dbiomass%2Bproduction','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920071656&hterms=biomass+production&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dbiomass%2Bproduction"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span> in NASA's biomass production chamber - A preprototype closed human life support system</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Corey, Kenneth A.; Wheeler, Raymond M.</p> <p>1992-01-01</p> <p>The unique capabilities of the NASA biomass production chamber for monitoring and evaluating <span class="hlt">gas</span> <span class="hlt">exchange</span> rates are examined. Special emphasis is given to results with wheat and soybeans. The potential of the chamber as a preprototype of a closed human life support system is considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23411504','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23411504"><span>Mini-extracorporeal circulation minimizes coagulation <span class="hlt">abnormalities</span> and ameliorates pulmonary outcome in coronary artery bypass grafting surgery.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zeitani, J; Buccisano, F; Nardella, S; Flaminio, M; Prati, P; Chiariello, G; Venditti, A; Chiariello, L</p> <p>2013-07-01</p> <p>Hemostasis is impaired during CABG and coagulation <span class="hlt">abnormalities</span> often result in clinically relevant organ dysfunctions, eventually increasing morbidity and mortality rates. Fifteen consecutive patients with coronary artery disease submitted to conventional extracorporeal circulation (cECC) have been compared with 15 matched patients, using mini-ECC (MECC). Postoperative lung function was evaluated according to <span class="hlt">gas</span> <span class="hlt">exchange</span>, intubation time and lung injury score. In the MECC group, thrombin-antithrombin complex levels (TaTc), prothrombin fragments (PF1+2) formation and thromboelastography (TEG) clotting times were lower compared to the cECC group (p=0.002 and p<0.001, respectively) whereas postoperative blood loss was higher in the cECC group (p=0.030) and more patients required blood transfusion (p=0.020). In the MECC group, postoperative <span class="hlt">gas</span> <span class="hlt">exchange</span> values were better, intubation time shorter and lung injury score lower (p<0.001 for all comparisons). Our study suggests that MECC induces less coagulation disorders, leading to lower postoperative blood loss and better postoperative lung function. This approach may be advantageous in high-risk patients.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/865765','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/865765"><span>Direct fired heat <span class="hlt">exchanger</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Reimann, Robert C.; Root, Richard A.</p> <p>1986-01-01</p> <p>A <span class="hlt">gas</span>-to-liquid heat <span class="hlt">exchanger</span> system which transfers heat from a <span class="hlt">gas</span>, generally the combustion <span class="hlt">gas</span> of a direct-fired generator of an absorption machine, to a liquid, generally an absorbent solution. The heat <span class="hlt">exchanger</span> system is in a counterflow fluid arrangement which creates a more efficient heat transfer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16667848','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16667848"><span>Influence of vesicular arbuscular mycorrhizae and leaf age on net <span class="hlt">gas</span> <span class="hlt">exchange</span> of citrus leaves.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Syvertsen, J P; Graham, J H</p> <p>1990-11-01</p> <p>The purpose of this study was to test the hypothesis that vesicular arbuscular mycorrhizal (VAM) fungi affect net assimilation of CO(2) (A) of different-aged citrus leaves independent of mineral nutrition effects of mycorrhizae. Citrus aurantium L., sour orange plants were grown for 6 months in a sandy soil low in phosphorus that was either infested with the VAM fungus, Glomus intraradices Schenck & Smith, or fertilized with additional phosphorus and left nonmycorrhizal (NM). Net CO(2) assimilation, stomatal conductance, water use efficiency, and mineral nutrient status for expanding, recently expanded, and mature leaves were evaluated as well as plant size and relative growth rate of leaves. Nutrient status and net <span class="hlt">gas</span> <span class="hlt">exchange</span> varied with leaf age. G. intraradices-inoculated plants had well-established colonization (79% of root length) and were comparable in relative growth rate and size at final harvest with NM plants. Leaf mineral concentrations were generally the same for VAM and NM plants except for nitrogen. Although leaf nitrogen was apparently sufficient for high rates of A, VAM plants did have higher nitrogen concentrations than NM at the time of <span class="hlt">gas</span> <span class="hlt">exchange</span> measurements. G. intraradices had no effect on A, stomatal conductance, or water use efficiency, irrespective of leaf age. These results show that well-established VAM colonization does not affect net <span class="hlt">gas</span> <span class="hlt">exchange</span> of citrus plants that are comparable in size, growth rate, and nutritional status with NM plants.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19077169','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19077169"><span>Surviving floods: leaf <span class="hlt">gas</span> films improve O₂ and CO₂ <span class="hlt">exchange</span>, root aeration, and growth of completely submerged rice.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pedersen, Ole; Rich, Sarah Meghan; Colmer, Timothy David</p> <p>2009-04-01</p> <p>When completely submerged, the leaves of some species retain a surface <span class="hlt">gas</span> film. Leaf <span class="hlt">gas</span> films on submerged plants have recently been termed 'plant plastrons', analogous with the plastrons of aquatic insects. In aquatic insects, surface <span class="hlt">gas</span> layers (i.e. plastrons) enlarge the <span class="hlt">gas</span>-water interface to promote O₂ uptake when under water; however, the function of leaf <span class="hlt">gas</span> films has rarely been considered. The present study demonstrates that <span class="hlt">gas</span> films on leaves of completely submerged rice facilitate entry of O₂ from floodwaters when in darkness and CO₂ entry when in light. O₂ microprofiles showed that the improved <span class="hlt">gas</span> <span class="hlt">exchange</span> was not caused by differences in diffusive boundary layers adjacent to submerged leaves with or without <span class="hlt">gas</span> films; instead, reduced resistance to <span class="hlt">gas</span> <span class="hlt">exchange</span> was probably due to the enlarged water-<span class="hlt">gas</span> interface (cf. aquatic insects). When <span class="hlt">gas</span> films were removed artificially, underwater net photosynthesis declined to only 20% of the rate with <span class="hlt">gas</span> films present, such that, after 7 days of complete submergence, tissue sugar levels declined, and both shoot and root growth were reduced. Internal aeration of roots in anoxic medium, when shoots were in aerobic floodwater in darkness or when in light, was improved considerably when leaf <span class="hlt">gas</span> films were present. Thus, leaf <span class="hlt">gas</span> films contribute to the submergence tolerance of rice, in addition to those traits already recognized, such as the shoot-elongation response, aerenchyma and metabolic adjustments to O₂ deficiency and oxidative stress. © 2009 The Authors. Journal compilation © 2009 Blackwell Publishing Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740058015&hterms=respiratory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Drespiratory','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740058015&hterms=respiratory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Drespiratory"><span>Respiratory <span class="hlt">gas</span> <span class="hlt">exchange</span> of high altitude adapted chick embryos</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wangensteen, O. D.; Rahn, H.; Burton, R. R.; Smith, A. H.</p> <p>1974-01-01</p> <p>Study of <span class="hlt">gas</span> <span class="hlt">exchange</span> by embryos from chickens acclimatized to an altitude of 3800 m. The oxygen partial pressure and carbon dioxide partial pressure differences across the egg shell were measured and found to be less than the values previously reported for sea-level eggs by about a factor of two. Further measurements of embryonic oxygen consumption and shell conductivity to oxygen indicated that, compared to eggs at sea level, oxygen consumption was reduced by a factor of 0.58 while conductivity to oxygen was increased only by a factor of 1.07 in the high-altitude eggs. These independent measurements predict the change in oxygen partial pressure across the egg shell of the high-altitude eggs to be only 0.54 times that of sea-level eggs; the directly measured factor was 0.53. The authors conclude that at high altitude, a major adaptation of the chick embryo is a reduced metabolism which decreases the change in oxygen partial pressure across the egg shell since its <span class="hlt">gas</span> conductivity remains essentially unchanged.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28215595','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28215595"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span> kinetics following concentric-eccentric isokinetic arm and leg exercise.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Drescher, U; Mookerjee, S; Steegmanns, A; Knicker, A; Hoffmann, U</p> <p>2017-06-01</p> <p>To evaluate the effects of exercise velocity (60, 150, 240deg∙s -1 ) and muscle mass (arm vs leg) on changes in <span class="hlt">gas</span> <span class="hlt">exchange</span> and arterio-venous oxygen content difference (avDO 2 ) following high-intensity concentric-eccentric isokinetic exercise. Fourteen subjects (26.9±3.1years) performed a 3×20-repetition isokinetic exercise protocol. Recovery beat-to-beat cardiac output (CO) and breath-by-breath <span class="hlt">gas</span> <span class="hlt">exchange</span> were recorded to determine post-exercise half-time (t 1/2 ) for oxygen uptake (V˙O 2 pulm), carbon dioxide output (V˙CO 2 pulm), and ventilation (V˙ E ). Significant differences of the t 1/2 values were identified between 60 and 150deg∙s -1 . Significant differences in the t 1/2 values were observed between V˙O 2 pulm and V˙CO 2 pulm and between V˙CO 2 pulm and V˙ E . The time to attain the first avDO 2 -peak showed significant differences between arm and leg exercise. The present study illustrates, that V˙O 2 pulm kinetics are distorted due to non-linear CO dynamics. Therefore, it has to be taken into account, that V˙O 2 pulm may not be a valuable surrogate for muscular oxygen uptake kinetics in the recovery phases. Copyright © 2017 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19203976','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19203976"><span>The hydraulic conductance of Fraxinus ornus leaves is constrained by soil water availability and coordinated with <span class="hlt">gas</span> <span class="hlt">exchange</span> rates.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gortan, Emmanuelle; Nardini, Andrea; Gascó, Antonio; Salleo, Sebastiano</p> <p>2009-04-01</p> <p>Leaf hydraulic conductance (Kleaf) is known to be an important determinant of plant <span class="hlt">gas</span> <span class="hlt">exchange</span> and photosynthesis. Little is known about the long-term impact of different environmental factors on the hydraulic construction of leaves and its eventual consequences on leaf <span class="hlt">gas</span> <span class="hlt">exchange</span>. In this study, we investigate the impact of soil water availability on Kleaf of Fraxinus ornus L. as well as the influence of Kleaf on <span class="hlt">gas</span> <span class="hlt">exchange</span> rates and plant water status. With this aim, Kleaf, leaf conductance to water vapour (gL), leaf water potential (Psileaf) and leaf mass per area (LMA) were measured in F. ornus trees, growing in 21 different sites with contrasting water availability. Plants growing in arid sites had lower Kleaf, gL and Psileaf than those growing in sites with higher water availability. On the contrary, LMA was similar in the two groups. The Kleaf values recorded in sites with two different levels of soil water availability were constantly different from each other regardless of the amount of precipitation recorded over 20 days before measurements. Moreover, Kleaf was correlated with gL values. Our data suggest that down-regulation of Kleaf is a component of adaptation of plants to drought-prone habitats. Low Kleaf implies reduced <span class="hlt">gas</span> <span class="hlt">exchange</span> which may, in turn, influence the climatic conditions on a local/regional scale. It is concluded that leaf hydraulics and its changes in response to resource availability should receive greater attention in studies aimed at modelling biosphere-atmosphere interactions.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780027541&hterms=thought+experiments&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dthought%2Bexperiments','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780027541&hterms=thought+experiments&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dthought%2Bexperiments"><span>The Viking <span class="hlt">gas</span> <span class="hlt">exchange</span> experiment results from Chryse and Utopia surface samples</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Oyama, V. I.; Berdahl, B. J.</p> <p>1977-01-01</p> <p>Immediate <span class="hlt">gas</span> changes occurred when untreated Martian surface samples were humidified and/or wet by an aqueous nutrient medium in the Viking lander <span class="hlt">gas</span> <span class="hlt">exchange</span> experiment. The evolutions of N2, CO2, and Ar are mainly associated with soil surface desorption caused by water vapor, while O2 evolution is primarily associated with decomposition of superoxides inferred to be present on Mars. On recharges with fresh nutrient and test <span class="hlt">gas</span>, only CO2 was given off, and its rate of evolution decreased with each recharge. This CO2 evolution is thought to come from the oxidation of organics present in the nutrient by gamma Fe2O3 in the surface samples. Atmospheric analyses were also performed at both sites. The mean atmospheric composition from four analyses is N2, 2.3%; O2, not greater than 0.15%; Ar, 1.5% and CO2, 96.2%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12578005','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12578005"><span>Effects of air current speed on <span class="hlt">gas</span> <span class="hlt">exchange</span> in plant leaves and plant canopies.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kitaya, Y; Tsuruyama, J; Shibuya, T; Yoshida, M; Kiyota, M</p> <p>2003-01-01</p> <p>To obtain basic data on adequate air circulation to enhance plant growth in a closed plant culture system in a controlled ecological life support system (CELSS), an investigation was made of the effects of the air current speed ranging from 0.01 to 1.0 m s-1 on photosynthesis and transpiration in sweetpotato leaves and photosynthesis in tomato seedlings canopies. The <span class="hlt">gas</span> <span class="hlt">exchange</span> rates in leaves and canopies were determined by using a chamber method with an infrared <span class="hlt">gas</span> analyzer. The net photosynthetic rate and the transpiration rate increased significantly as the air current speeds increased from 0.01 to 0.2 m s-1. The transpiration rate increased gradually at air current speeds ranging from 0.2 to 1.0 m s-1 while the net photosynthetic rate was almost constant at air current speeds ranging from 0.5 to 1.0 m s-1. The increase in the net photosynthetic and transpiration rates were strongly dependent on decreased boundary-layer resistances against <span class="hlt">gas</span> diffusion. The net photosynthetic rate of the plant canopy was doubled by an increased air current speed from 0.1 to 1.0 m s-1 above the plant canopy. The results demonstrate the importance of air movement around plants for enhancing the <span class="hlt">gas</span> <span class="hlt">exchange</span> in the leaf, especially in plant canopies in the CELSS. c2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28620915','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28620915"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span> recovery following natural drought is rapid unless limited by loss of leaf hydraulic conductance: evidence from an evergreen woodland.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Skelton, Robert P; Brodribb, Timothy J; McAdam, Scott A M; Mitchell, Patrick J</p> <p>2017-09-01</p> <p>Drought can cause major damage to plant communities, but species damage thresholds and postdrought recovery of forest productivity are not yet predictable. We used an El Niño drought event as a natural experiment to test whether postdrought recovery of <span class="hlt">gas</span> <span class="hlt">exchange</span> could be predicted by properties of the water transport system, or if metabolism, primarily high abscisic acid concentration, might delay recovery. We monitored detailed physiological responses, including shoot sapflow, leaf <span class="hlt">gas</span> <span class="hlt">exchange</span>, leaf water potential and foliar abscisic acid (ABA), during drought and through the subsequent rehydration period for a sample of eight canopy and understory species. Severe drought caused major declines in leaf water potential, elevated foliar ABA concentrations and reduced stomatal conductance and assimilation rates in our eight sample species. Leaf water potential surpassed levels associated with incipient loss of leaf hydraulic conductance in four species. Following heavy rainfall <span class="hlt">gas</span> <span class="hlt">exchange</span> in all species, except those trees predicted to have suffered hydraulic impairment, recovered to prestressed rates within 1 d. Recovery of plant <span class="hlt">gas</span> <span class="hlt">exchange</span> was rapid and could be predicted by the hydraulic safety margin, providing strong support for leaf vulnerability to water deficit as an index of damage under natural drought conditions. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28879605','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28879605"><span>In-vitro evaluation of limitations and possibilities for the future use of intracorporeal <span class="hlt">gas</span> <span class="hlt">exchangers</span> placed in the upper lobe position.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schumer, Erin; Höffler, Klaus; Kuehn, Christian; Slaughter, Mark; Haverich, Axel; Wiegmann, Bettina</p> <p>2018-03-01</p> <p>The lack of donor organs has led to the development of alternative "destination therapies", such as a bio-artificial lung (BA) for end-stage lung disease. Ultimately aiming at a fully implantable BA, general capabilities and limitations of different oxygenators were tested based on the model of BA positioning at the right upper lobe. Three different-sized oxygenators (neonatal, paediatric, and adult) were tested in a mock circulation loop regarding oxygenation and decarboxylation capacities for three respiratory pathologies. Blood flows were imitated by a roller pump, and respiration was imitated by a mechanical ventilator with different FiO 2 applications. Pressure drops across the oxygenators and the integrity of the <span class="hlt">gas-exchange</span> hollow fibers were analyzed. The neonatal oxygenator proved to be insufficient regarding oxygenation and decarboxylation. Despite elevated pCO 2 levels, the paediatric and adult oxygenators delivered comparable sufficient oxygen levels, but sufficient decarboxylation across the oxygenators was ensured only at flow rates of 0.5 L min. Only the adult oxygenator indicated no significant pressure drops. For all tested conditions, <span class="hlt">gas-exchange</span> hollow fibers remained intact. This is the first study showing the general feasibility of delivering sufficient levels of <span class="hlt">gas</span> <span class="hlt">exchange</span> to an intracorporeal BA via patient's breathing, without damaging <span class="hlt">gas-exchange</span> hollow fiber membranes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998EPJAP...3..295B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998EPJAP...3..295B"><span>Optimization of heat and mass transfers in counterflow corrugated-plate liquid-<span class="hlt">gas</span> <span class="hlt">exchangers</span> used in a greenhouse dehumidifier</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bentounes, N.; Jaffrin, A.</p> <p>1998-09-01</p> <p>Heat and mass transfers occuring in a counterflow direct contact liquid-<span class="hlt">gas</span> <span class="hlt">exchanger</span> determine the performance of a new greenhouse air dehumidifier designed at INRA. This prototype uses triethylene glycol (TEG) as the desiccant fluid which extracts water vapor from the air. The regeneration of the TEG desiccant fluid is then performed by direct contact with combustion <span class="hlt">gas</span> from a high efficiency boiler equipped with a condensor. The heat and mass transfers between the thin film of diluted TEG and the hot <span class="hlt">gas</span> were simulated by a model which uses correlation formula from the literature specifically relevant to the present cross-corrugated plates geometry. A simple set of analytical solutions is first derived, which explains why some possible processes can clearly be far from optimal. Then, more exact numerical calculations confirm that some undesirable water recondensations on the upper part of the <span class="hlt">exchanger</span> were limiting the performance of this prototype. More suitable conditions were defined for the process, which lead to a new design of the apparatus. In this second prototype, a <span class="hlt">gas-gas</span> <span class="hlt">exchanger</span> provides dryer and cooler <span class="hlt">gas</span> to the basis of the regenerators, while a warmer TEG is fed on the top. A whole range of operating conditions was experimented and measured parameters were compared with numerical simulations of this new configuration: recondensation did not occur any more. As a consequence, this second prototype was able to concentrate the desiccant fluid at the desired rate of 20 kg H_{2O}/hour, under temperature and humidity conditions which correspond to the dehumidification of a 1000 m2 greenhouse heated at night during the winter season.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2780404','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2780404"><span>Long-term <span class="hlt">gas</span> <span class="hlt">exchange</span> characteristics as markers of deterioration in patients with cystic fibrosis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2009-01-01</p> <p>Background and Aim In patients with cystic fibrosis (CF) the architecture of the developing lungs and the ventilation of lung units are progressively affected, influencing intrapulmonary <span class="hlt">gas</span> mixing and <span class="hlt">gas</span> <span class="hlt">exchange</span>. We examined the long-term course of blood <span class="hlt">gas</span> measurements in relation to characteristics of lung function and the influence of different CFTR genotype upon this process. Methods Serial annual measurements of PaO2 and PaCO2 assessed in relation to lung function, providing functional residual capacity (FRCpleth), lung clearance index (LCI), trapped <span class="hlt">gas</span> (VTG), airway resistance (sReff), and forced expiratory indices (FEV1, FEF50), were collected in 178 children (88 males; 90 females) with CF, over an age range of 5 to 18 years. Linear mixed model analysis and binary logistic regression analysis were used to define predominant lung function parameters influencing oxygenation and carbon dioxide elimination. Results PaO2 decreased linearly from age 5 to 18 years, and was mainly associated with FRCpleth, (p < 0.0001), FEV1 (p < 0.001), FEF50 (p < 0.002), and LCI (p < 0.002), indicating that oxygenation was associated with the degree of pulmonary hyperinflation, ventilation inhomogeneities and impeded airway function. PaCO2 showed a transitory phase of low PaCO2 values, mainly during the age range of 5 to 12 years. Both PaO2 and PaCO2 presented with different progression slopes within specific CFTR genotypes. Conclusion In the long-term evaluation of <span class="hlt">gas</span> <span class="hlt">exchange</span> characteristics, an association with different lung function patterns was found and was closely related to specific genotypes. Early examination of blood gases may reveal hypocarbia, presumably reflecting compensatory mechanisms to improve oxygenation. PMID:19909502</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=245933','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=245933"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span> and water relations responses of spring wheat to full-season infrared warming</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p><span class="hlt">Gas</span> <span class="hlt">exchange</span> and water relations responses to full-season in situ infrared (IR) warming were evaluated for hard red spring wheat (Triticum aestivum L. cv. Yecora Rojo) grown in an open field in a semi-arid desert region of the Southwest USA. A Temperature Free-Air Controlled Enhancement (T-FACE) ap...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=276837','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=276837"><span><span class="hlt">Gas</span> <span class="hlt">Exchange</span> and Water Relations Responses of Spring Wheat to Full-Season Infrared Warming</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p><span class="hlt">Gas</span> <span class="hlt">exchange</span> and water relations were evaluated under full-season in situ infrared (IR) warming for hard red spring wheat (Triticum aestivum L. cv. Yecora Rojo) grown in an open field in a semiarid desert region of the southwest USA. A temperature free-air controlled enhancement (T-FACE) apparatus u...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9609803','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9609803"><span>Modeling bronchial circulation with application to soluble <span class="hlt">gas</span> <span class="hlt">exchange</span>: description and sensitivity analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bui, T D; Dabdub, D; George, S C</p> <p>1998-06-01</p> <p>The steady-state <span class="hlt">exchange</span> of inert gases across an in situ canine trachea has recently been shown to be limited equally by diffusion and perfusion over a wide range (0.01-350) of blood solubilities (betablood; ml . ml-1 . atm-1). Hence, we hypothesize that the <span class="hlt">exchange</span> of ethanol (betablood = 1,756 at 37 degrees C) in the airways depends on the blood flow rate from the bronchial circulation. To test this hypothesis, the dynamics of the bronchial circulation were incorporated into an existing model that describes the simultaneous <span class="hlt">exchange</span> of heat, water, and a soluble <span class="hlt">gas</span> in the airways. A detailed sensitivity analysis of key model parameters was performed by using the method of Latin hypercube sampling. The model accurately predicted a previously reported experimental exhalation profile of ethanol (R2 = 0.991) as well as the end-exhalation airstream temperature (34.6 degrees C). The model predicts that 27, 29, and 44% of exhaled ethanol in a single exhalation are derived from the tissues of the mucosa and submucosa, the bronchial circulation, and the tissue exterior to the submucosa (which would include the pulmonary circulation), respectively. Although the concentration of ethanol in the bronchial capillary decreased during inspiration, the three key model outputs (end-exhaled ethanol concentration, the slope of phase III, and end-exhaled temperature) were all statistically insensitive (P > 0.05) to the parameters describing the bronchial circulation. In contrast, the model outputs were all sensitive (P < 0.05) to the thickness of tissue separating the core body conditions from the bronchial smooth muscle. We conclude that both the bronchial circulation and the pulmonary circulation impact soluble <span class="hlt">gas</span> <span class="hlt">exchange</span> when the entire conducting airway tree is considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/1067','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/1067"><span>Aluminum toxicity in tomato. Part 2.Leaf <span class="hlt">gas</span> <span class="hlt">exchange</span>, chlorophyll content, and invertase activity</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>L. Simon; M. Kieger; Shi-Jean S. Sung; T.J. Smalley</p> <p>1994-01-01</p> <p>The effect of aluminum (Al) toxicity on leaf <span class="hlt">gas</span> <span class="hlt">exchange</span>, leaf chlorophyll content, and sucrose metabolizing enzyme activity of two tomato cultivars (Lycopersicon esculentum Mill. 'Mountain Pride' and 'Floramerica') was studied to determine the mechanism of growth reduction observed in a related study (Simon et al., 1994, Part 1).Plants were grown...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17936295','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17936295"><span>Breathe softly, beetle: continuous <span class="hlt">gas</span> <span class="hlt">exchange</span>, water loss and the role of the subelytral space in the tenebrionid beetle, Eleodes obscura.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schilman, Pablo E; Kaiser, Alexander; Lighton, John R B</p> <p>2008-01-01</p> <p>Flightless, diurnal tenebrionid beetles are commonly found in deserts. They possess a curious morphological adaptation, the subelytral cavity (an air space beneath the fused elytra) the function of which is not completely understood. In the tenebrionid beetle Eleodes obscura, we measured abdominal movements within the subelytral cavity, and the activity of the pygidial cleft (which seals or unseals the subelytral cavity), simultaneously with total CO2 release rate and water loss rate. First, we found that E. obscura has the lowest cuticular permeability measured in flow-through respirometry in an insect (0.90 microg H2O cm(-2) Torr(-1) h(-1)). Second, it does not exhibit a discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> cycle. Third, we describe the temporal coupling between <span class="hlt">gas</span> <span class="hlt">exchange</span>, water loss, subelytral space volume, and the capacity of the subelytral space to <span class="hlt">exchange</span> gases with its surroundings as indicated by pygidial cleft state. Fourth, we suggest possible mechanisms that may reduce respiratory water loss rates in E. obscura. Finally, we suggest that E. obscura cannot <span class="hlt">exchange</span> respiratory gases discontinuously because of a morphological constraint (small tracheal or spiracular conductance). This "conductance constraint hypothesis" may help to explain the otherwise puzzling phylogenetic patterns of continuous vs. discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> observed in tracheate arthropods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28577386','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28577386"><span>Hydraulics and <span class="hlt">gas</span> <span class="hlt">exchange</span> recover more rapidly from severe drought stress in small pot-grown grapevines than in field-grown plants.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Romero, Pascual; Botía, Pablo; Keller, Markus</p> <p>2017-09-01</p> <p>Modifications of plant hydraulics and shoot resistances (R shoot ) induced by water withholding followed by rewatering, and their relationships with plant water status, leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and water use efficiency at the leaf level, were investigated in pot-grown and field-grown, own-rooted Syrah grapevines in an arid climate. Water stress induced anisohydric behavior, gradually reducing stomatal conductance (g s ) and leaf photosynthesis (A) in response to decreasing midday stem water potential (Ψ s ). Water stress also rapidly increased intrinsic water-use efficiency (A/g s ); this effect persisted for many days after rewatering. Whole-plant (K plant ), canopy (K canopy ), shoot (K shoot ) and leaf (K leaf ) hydraulic conductances decreased during water stress, in tune with the gradual decrease in Ψ s , leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and whole plant water use. Water-stressed vines also had a lower Ψ gradient between stem and leaf (ΔΨ l ), which was correlated with lower leaf transpiration rate (E). E and ΔΨ l increased with increasing vapour pressure deficit (VPD) in non-stressed control vines but not in stressed vines. Perfusion of xylem-mobile dye showed that water flow to petioles and leaves was substantially reduced or even stopped under moderate and severe drought stress. Leaf blade hydraulic resistance accounted for most of the total shoot resistance. However, hydraulic conductance of the whole root system (K root ) was not significantly reduced until water stress became very severe in pot-grown vines. Significant correlations between K plant , K canopy and Ψ s , K canopy and leaf <span class="hlt">gas</span> <span class="hlt">exchange</span>, K leaf and Ψ s , and K leaf and A support a link between water supply, leaf water status and <span class="hlt">gas</span> <span class="hlt">exchange</span>. Upon re-watering, Ψ s recovered faster than <span class="hlt">gas</span> <span class="hlt">exchange</span> and leaf-shoot hydraulics. A gradual recovery of hydraulic functionality of plant organs was also observed, the leaves being the last to recover after rewatering. In pot-grown vines, K canopy recovered rather</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10194147','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10194147"><span>Effect of body position changes on pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> in Eisenmenger's syndrome.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sandoval, J; Alvarado, P; Martínez-Guerra, M L; Gómez, A; Palomar, A; Meza, S; Santos, E; Rosas, M</p> <p>1999-04-01</p> <p>Preliminary studies on sleep of patients with congenital heart disease and Eisenmenger's syndrome (ES) at our institution demonstrated nocturnal worsening arterial unsaturation, which appeared to be a body position-related phenomenon. To investigate the potential effect of body position on <span class="hlt">gas</span> <span class="hlt">exchange</span> in ES, we carried out a prospective study of 28 patients (mean age, 34.8 +/- 11.7 yr) with established ES due to congenital heart disease. In every patient, arterial blood gases were performed during both sitting and supine positions under three different conditions: room air, while breathing 100% oxygen, and after breathing oxygen at a flow rate of 3 L/min through nasal prongs. Alveolar oxygen pressure (PaO2) for the calculation of alveolar-arterial oxygen tension differences (AaPO2) was derived from the alveolar <span class="hlt">gas</span> equation using PaCO2 and assuming R = 1. We used paired t test, repeated-measures two-way ANOVA with Bonferroni's test, and regression analysis. From sitting to supine position on room air, there was a significant decrease in PaO2 (from 52.5 +/- 7.5 to 47.5 +/- 5.5 mm Hg; p < 0. 001) and SaO2 (from 86.7 +/- 4.6 to 83.3 +/- 4.9%; p < 0.001), both of which were corrected by nasal O2 (to 68.2 +/- 21 mm Hg and to 92 +/- 4%, respectively, p < 0.005). PaCO2 and pH remained unchanged. The magnitude of the change in PaO2 correlated with the change in AaPO2 on room air (r = 0.77; p < 0.01) but not with the change in AaPO2 on 100% oxygen. It is concluded that in adult patients with ES there is a significant decrease in PaO2 and SaO2 when they change from the sitting to the supine position. A ventilation-perfusion (V/Q) distribution <span class="hlt">abnormality</span> and/or a diffusion limitation phenomenon rather than an increase in true shunt may be the mechanisms responsible for this finding. The response to nasal O 2 we observed warrants a trial with long-term nocturnal oxygen therapy in these patients.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70023354','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70023354"><span>Carbon <span class="hlt">gas</span> <span class="hlt">exchange</span> at a southern Rocky Mountain wetland, 1996-1998</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Wickland, K.P.; Striegl, Robert G.; Mast, M.A.; Clow, D.W.</p> <p>2001-01-01</p> <p>Carbon dioxide (CO2) and methane (CH4) <span class="hlt">exchange</span> between the atmosphere and a subalpine wetland located in Rocky Mountain National Park, Colorado, at 3200 m elevation were measured during 1996-1998. Respiration, net CO2 flux, and CH4 flux were measured using the closed chamber method during snow-free periods and using <span class="hlt">gas</span> diffusion calculations during snow-covered periods. The ranges of measured flux were 1.2-526 mmol CO2 m-2 d-1 (respiration), -1056-100 mmol CO2 m-2 d-1 (net CO2 <span class="hlt">exchange</span>), and 0.1-36.8 mmol CH4 m-2 d-1 (a positive value represents efflux to the atmosphere). Respiration and CH4 emission were significantly correlated with 5 cm soil temperature. Annual respiration and CH4 emission were modeled by applying the flux-temperature relationships to a continuous soil temperature record during 1996-1998. Gross photosynthesis was modeled using a hyperbolic equation relating gross photosynthesis, photon flux density, and soil temperature. Modeled annual flux estimates indicate that the wetland was a net source of carbon <span class="hlt">gas</span> to the atmosphere each of the three years: 8.9 mol C m-2 yr-1 in 1996, 9.5 mol C m-2 yr-1 in 1997, and 9.6 mol C m-2 yr-1 in 1998. This contrasts with the long-term carbon accumulation of ???0.7 mol m-2 yr-1 determined from 14C analyses of a peat core collected from the wetland.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008OSJ....43...17L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008OSJ....43...17L"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span> rates measured using a dual-tracer (SF6 and3he) method in the coastal waters of Korea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Hyun-Woo; Lee, Kitack; Kaown, Duk-In</p> <p>2008-03-01</p> <p>Over a period of 5 days between August 12 and 17, 2005, we performed a <span class="hlt">gas</span> <span class="hlt">exchange</span> experiment using the dual tracer method in a tidal coastal ocean located off the southern coast of Korea. The <span class="hlt">gas</span> <span class="hlt">exchange</span> rate was determined from temporal changes in the ratio of3He to SF6 measured daily in the surface mixed layer. The measured <span class="hlt">gas</span> <span class="hlt">exchange</span> rate ( k CO 2), normalized to a Schmidt number of 600 for CO2 in fresh water at 20°C, was approximately 5.0 cm h-1 at a mean wind speed of 3.9 m s-1 during the study period. This value is significantly less than those obtained from floating chamber-based experiments performed previously in estuarine environments, but is similar in magnitude to values obtained using the dual tracer method in river and tidal coastal waters and values predicted on the basis of the relationship between the <span class="hlt">gas</span> <span class="hlt">exchange</span> rate and wind speed (Wanninkhof 1992), which is generally applicable to the open ocean. Our result is also consistent with the relationship of Raymond and Cole (2001), which was derived from experiments carried out in estuarine environments using222Rn and chlorofluorocarbons along with measurements undertaken in the Hudson River, Canada, using SF6 and3He. Our results indicate that tidal action in a microtidal region did not discernibly enhance the measured k CO 2 value.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090004422','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090004422"><span>Effect of Adding a Regenerator to Kornhauser's MIT "Two-Space" (<span class="hlt">Gas</span>-Spring+Heat <span class="hlt">Exchanger</span>) Test Rig</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ebiana, Asuquo B.; Gidugu, Praveen</p> <p>2008-01-01</p> <p>This study employed entropy-based second law post-processing analysis to characterize the various thermodynamic losses inside a 3-space solution domain (<span class="hlt">gas</span> spring+heat <span class="hlt">exchanger</span>+regenerator) operating under conditions of oscillating pressure and oscillating flow. The 3- space solution domain is adapted from the 2-space solution domain (<span class="hlt">gas</span> spring+heat <span class="hlt">exchanger</span>) in Kornhauser's MIT test rig by modifying the heat <span class="hlt">exchanger</span> space to include a porous regenerator system. A thermal nonequilibrium model which assumes that the regenerator porous matrix and <span class="hlt">gas</span> average temperatures can differ by several degrees at a given axial location and time during the cycle is employed. An important and primary objective of this study is the development and application of a thermodynamic loss post-processor to characterize the major thermodynamic losses inside the 3-space model. It is anticipated that the experience gained from thermodynamic loss analysis of the simple 3-space model can be extrapolated to more complex systems like the Stirling engine. It is hoped that successful development of loss post-processors will facilitate the improvement of the optimization capability of Stirling engine analysis codes through better understanding of the heat transfer and power losses. It is also anticipated that the incorporation of a successful thermal nonequilibrium model of the regenerator in Stirling engine CFD analysis codes, will improve our ability to accurately model Stirling regenerators relative to current multidimensional thermal-equilibrium porous media models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12780507','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12780507"><span>Extracorporeal <span class="hlt">gas</span> <span class="hlt">exchange</span> with the DeltaStream rotary blood pump in experimental lung injury.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dembinski, Rolf; Kopp, Rüdger; Henzler, Dietrich; Hochhausen, Nadine; Oslender, Nicole; Max, Martin; Rossaint, Rolf; Kuhlen, Ralf</p> <p>2003-06-01</p> <p>In most severe cases of the acute respiratory distress syndrome, veno-venous extracorporeal membrane oxygenation (ECMO) can be used to facilitate <span class="hlt">gas</span> <span class="hlt">exchange</span>. However, the clinical use is limited due to the size and the concomitant risk of severe adverse events of conventionally-used centrifugal blood pumps with high extracorporeal blood volumes. The DeltaStream blood pump is a small-sized rotary blood pump that may reduce extracorporeal blood volume, foreign surfaces, contact activation of the coagulation system, and blood trauma. The aim of the present study was to test the safety and efficacy of the DeltaStream pump for ECMO in animals with normal lung function and experimental acute lung injury (ALI). Therefore, veno-venous ECMO was performed for 6 hours in mechanically ventilated pigs with normal lung function (n=6) and with ALI induced by repeated lung lavage (n=6) with a blood flow of 30% of the cardiac output. <span class="hlt">Gas</span> flow with a FiO2 of 1.0 was set to equal blood flow. With a mean activated clotting time of 121 +/- 22 s, no circulatory impairment or thrombus formation was revealed during ECMO. Furthermore, free plasma Hb did not increase. In controls, hemodynamics and <span class="hlt">gas</span> <span class="hlt">exchange</span> remained unchanged. In animals with ALI, hemodynamics remained stable and <span class="hlt">gas</span> transfer across the extracorporeal oxygenators was optimal, but only in 2 animals was a marked increase in PaO2 observed. CO2 removal was efficacious in all animals. We concluded that the DeltaStream blood pump may be used for veno-venous ECMO without major blood damage or hemodynamic impairment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=464594','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=464594"><span>Use of a combined oxygen and carbon dioxide transcutaneous electrode in the estimation of <span class="hlt">gas</span> <span class="hlt">exchange</span> during exercise.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sridhar, M K; Carter, R; Moran, F; Banham, S W</p> <p>1993-01-01</p> <p>BACKGROUND--Accurate and reliable measurement of <span class="hlt">gas</span> <span class="hlt">exchange</span> during exercise has traditionally involved arterial cannulation. Non-invasive devices to estimate arterial oxygen (O2) and carbon dioxide (CO2) tensions are now available. A method has been devised and evaluated for measuring <span class="hlt">gas</span> <span class="hlt">exchange</span> during exercise with a combined transcutaneous O2 and CO2 electrode. METHODS--Symptom limited exercise tests were carried out in 24 patients reporting effort intolerance and breathlessness. Exercise testing was performed by bicycle ergometry with a specifically designed protocol involving gradual two minute workload increments. Arterial O2 and CO2 tensions were measured at rest and during exercise by direct blood sampling from an indwelling arterial cannula and a combined transcutaneous electrode heated to 45 degrees C. The transcutaneous system was calibrated against values obtained by direct arterial sampling before each test. RESULTS--In all tests the trend of <span class="hlt">gas</span> <span class="hlt">exchange</span> measured by the transcutaneous system was true to the trend measured from direct arterial sampling. In the 140 measurements the mean difference between the O2 tensions estimated by direct sampling and the transcutaneous method was 0.08 kPa (0.62 mm Hg, limits of agreement 4.42 and -3.38 mm Hg). The mean difference between the methods for CO2 was 0.02 kPa (0.22 mm Hg, limits of agreement 2.20 and -1.70 mm Hg). There was no morbidity associated with the use of the transcutaneous electrode heated to 45 degrees C. CONCLUSIONS--A combined transcutaneous O2 and CO2 electrode heated to 45 degrees C can be used to provide a reliable estimate of <span class="hlt">gas</span> <span class="hlt">exchange</span> during gradual incremental exercise in adults. PMID:8346496</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24854169','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24854169"><span>Dynamics of leaf <span class="hlt">gas</span> <span class="hlt">exchange</span>, xylem and phloem transport, water potential and carbohydrate concentration in a realistic 3-D model tree crown.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nikinmaa, Eero; Sievänen, Risto; Hölttä, Teemu</p> <p>2014-09-01</p> <p>Tree models simulate productivity using general <span class="hlt">gas</span> <span class="hlt">exchange</span> responses and structural relationships, but they rarely check whether leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and resulting water and assimilate transport and driving pressure gradients remain within acceptable physical boundaries. This study presents an implementation of the cohesion-tension theory of xylem transport and the Münch hypothesis of phloem transport in a realistic 3-D tree structure and assesses the <span class="hlt">gas</span> <span class="hlt">exchange</span> and transport dynamics. A mechanistic model of xylem and phloem transport was used, together with a tested leaf assimilation and transpiration model in a realistic tree architecture to simulate leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and water and carbohydrate transport within an 8-year-old Scots pine tree. The model solved the dynamics of the amounts of water and sucrose solute in the xylem, cambium and phloem using a fine-grained mesh with a system of coupled ordinary differential equations. The simulations predicted the observed patterns of pressure gradients and sugar concentration. Diurnal variation of environmental conditions influenced tree-level gradients in turgor pressure and sugar concentration, which are important drivers of carbon allocation. The results and between-shoot variation were sensitive to structural and functional parameters such as tree-level scaling of conduit size and phloem unloading. Linking whole-tree-level water and assimilate transport, <span class="hlt">gas</span> <span class="hlt">exchange</span> and sink activity opens a new avenue for plant studies, as features that are difficult to measure can be studied dynamically with the model. Tree-level responses to local and external conditions can be tested, thus making the approach described here a good test-bench for studies of whole-tree physiology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10757569','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10757569"><span>Effect of PEEP and inhaled nitric oxide on pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> during gaseous and partial liquid ventilation with small volumes of perfluorocarbon.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Max, M; Kuhlen, R; Falter, F; Reyle-Hahn, M; Dembinski, R; Rossaint, R</p> <p>2000-04-01</p> <p>Partial liquid ventilation, positive end-expiratory pressure (PEEP) and inhaled nitric oxide (NO) can improve ventilation/perfusion mismatch in acute lung injury (ALI). The aim of the present study was to compare <span class="hlt">gas</span> <span class="hlt">exchange</span> and hemodynamics in experimental ALI during gaseous and partial liquid ventilation at two different levels of PEEP, with and without the inhalation of nitric oxide. Seven pigs (24+/-2 kg BW) were surfactant-depleted by repeated lung lavage with saline. <span class="hlt">Gas</span> <span class="hlt">exchange</span> and hemodynamic parameters were assessed in all animals during gaseous and subsequent partial liquid ventilation at two levels of PEEP (5 and 15 cmH2O) and intermittent inhalation of 10 ppm NO. Arterial oxygenation increased significantly with a simultaneous decrease in cardiac output when PEEP 15 cmH2O was applied during gaseous and partial liquid ventilation. All other hemodynamic parameters revealed no relevant changes. Inhalation of NO and instillation of perfluorocarbon had no additive effects on pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> when compared to PEEP 15 cmH2O alone. In experimental lung injury, improvements in <span class="hlt">gas</span> <span class="hlt">exchange</span> are most distinct during mechanical ventilation with PEEP 15 cmH2O without significantly impairing hemodynamics. Partial liquid ventilation and inhaled NO did not cause an additive increase of PaO2.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JBO....21l7007H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JBO....21l7007H"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span> in fruits related to skin condition and fruit ripening studied with diode laser spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Jing; Zhang, Hao; Lin, Huiying; Li, Tianqi; Mei, Liang; Svanberg, Katarina; Svanberg, Sune</p> <p>2016-12-01</p> <p>The concentration of the biologically active molecular oxygen <span class="hlt">gas</span> is of crucial importance for fruits in the metabolic respiration, maturation, and ripening processes. In our study, oxygen content and oxygen transport in fruits, exemplified by apples and guavas, were studied noninvasively by <span class="hlt">gas</span> in scattering media absorption spectroscopy. The technique is based on the fact that free gases typically have 10,000 times narrower absorption features than the bulk material. The technique was demonstrated in studies of the influence of the fruit skin in regulating the internal oxygen balance, by observing the signal response of the internal oxygen <span class="hlt">gas</span> to a transient change in the ambient <span class="hlt">gas</span> concentration on peeled and unpeeled fruits. In addition, the <span class="hlt">gas</span> <span class="hlt">exchange</span> rate at different ripening stages was also studied in intact guavas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28008448','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28008448"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span> in fruits related to skin condition and fruit ripening studied with diode laser spectroscopy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huang, Jing; Zhang, Hao; Lin, Huiying; Li, Tianqi; Mei, Liang; Svanberg, Katarina; Svanberg, Sune</p> <p>2016-12-01</p> <p>The concentration of the biologically active molecular oxygen <span class="hlt">gas</span> is of crucial importance for fruits in the metabolic respiration, maturation, and ripening processes. In our study, oxygen content and oxygen transport in fruits, exemplified by apples and guavas, were studied noninvasively by <span class="hlt">gas</span> in scattering media absorption spectroscopy. The technique is based on the fact that free gases typically have 10,000 times narrower absorption features than the bulk material. The technique was demonstrated in studies of the influence of the fruit skin in regulating the internal oxygen balance, by observing the signal response of the internal oxygen <span class="hlt">gas</span> to a transient change in the ambient <span class="hlt">gas</span> concentration on peeled and unpeeled fruits. In addition, the <span class="hlt">gas</span> <span class="hlt">exchange</span> rate at different ripening stages was also studied in intact guavas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17330473','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17330473"><span>[<span class="hlt">Gas</span> <span class="hlt">exchange</span> features of Ambrosia artemisiifolia leaves and fruits and their correlations with soil heavy metals].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zu, Yuangang; Wang, Wenjie; Chen, Huafeng; Yang, Fengjian; Zhang, Zhonghua</p> <p>2006-12-01</p> <p>Ambrosia artemisiifolia can survive well in the habitats of heavy human disturbance and partial soil pollution. Weather its photosynthetic features benefit their survival is worthwhile to concern. With a refuse dump in Changchun City (43 degrees 50'N, 125 degrees 23'E) as study site, this paper analyzed the contents of soil Cu, Pb, Zn, Mn, Cr, Co, Ni, Cd, As, Sb and Hg at ten plots, and measured in situ the <span class="hlt">gas</span> <span class="hlt">exchange</span> in A. artemisiifolia leaves and young fruits. The results showed that the study site was slightly contaminated by Ni, but the contents of other soil heavy metals were approached to or substantially lower than their threshold values. The net photosynthetic rate of leaves ranged from 1.88 to 9.41 micromol x m(-2) x s(-1), while that of young fruits could be up to 2. 81 micromol x m(-2) s(-1). Averagely, the respiration rate, stomatal conductance, photosynthetic rate, and water utilization efficiency of leaves were 1.81 micromol x m(-2) x s(-1), 75.7 mmol x m(-2) x s(-1), 6.05 micromol x m(-2) x s(-1), and 4.72 micromol CO2 x mmol(-1) H2O, being 5.26, 0.64, 1.31 and 1.69 times as much as those of young fruits, respectively, indicating that the respiratory and photosynthetic capacities and water use efficiency of A. artemisiifolia young fruits were equivalent to or higher than those of its leaves. Many test heavy metals, such as Cu, Pb, Zn, Cd, As, Sb and Hg, had no significant effects on the <span class="hlt">gas</span> <span class="hlt">exchange</span> features of leaves and fruits, but there were significant correlations of Ni and Cr with the stomatal conductance and water use efficiency of leaves and young fruits, Cr with the gross photosynthesis of leaves, and As with the stomatal conductance of young fruits, suggesting that a majority of test soil heavy metals had no direct effects on the <span class="hlt">gas</span> <span class="hlt">exchange</span> in A. artemisiifolia leaves and fruits, but soil Ni, Cr and As with the contents approached to or substantially lower than the threshold values could affect the <span class="hlt">gas</span> <span class="hlt">exchange</span> features of A</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17938120','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17938120"><span>Leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> of understory spruce-fir saplings in relict cloud forests, southern Appalachian Mountains, USA.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Reinhardt, Keith; Smith, William K</p> <p>2008-01-01</p> <p>The southern Appalachian spruce-fir (Picea rubens Sarg. and Abies fraseri (Pursh) Poir.) forest is found only on high altitude mountain tops that receive copious precipitation ( > 2000 mm year(-1)) and experience frequent cloud immersion. These high-elevation, temperate rain forests are immersed in clouds on approximately 65% of the total growth season days and for 30-40% of a typical summer day, and cloud deposition accounts for up to 50% of their annual water budget. We investigated environmental influences on understory leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and water relations at two sites: Mt. Mitchell, NC (MM; 35 degrees 45'53'' N, 82 degrees 15'53'' W, 2028 m elevation) and Whitetop Mtn., VA (WT; 36 degrees 38'19'' N, 81 degrees 36'19'' W, 1685 m elevation). We hypothesized that the cool, moist and cloudy conditions at these sites exert a strong influence on leaf <span class="hlt">gas</span> <span class="hlt">exchange</span>. Maximum photosynthesis (A(max)) varied between 1.6 and 4.0 micromol CO(2) m(-2) s(-1) for both spruce and fir and saturated at irradiances between approximately 200 and 400 micromol m(-2) s(-1) at both sites. Leaf conductance (g) ranged between 0.05 and 0.25 mol m(-2) s(-1) at MM and between 0.15 and 0.40 mol m(-2) s(-1) at WT and was strongly associated with leaf-to-air vapor pressure difference (LAVD). At both sites, g decreased exponentially as LAVD increased, with an 80-90% reduction in g between 0 and 0.5 kPa. Predawn leaf water potentials remained between -0.25 and -0.5 MPa for the entire summer, whereas late afternoon values declined to between -1.25 and -1.75 MPa by late summer. Thus, leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> appeared tightly coupled to the response of g to LAVD, which maintained high water status, even at the relatively low LAVD of these cloud forests. Moreover, the cloudy, humid environment of these refugial forests appears to exert a strong influence on tree leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and water relations. Because global climate change is predicted to increase regional cloud ceiling levels, more research on</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26478739','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26478739"><span>A whole-plant chamber system for parallel <span class="hlt">gas</span> <span class="hlt">exchange</span> measurements of Arabidopsis and other herbaceous species.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kölling, Katharina; George, Gavin M; Künzli, Roland; Flütsch, Patrick; Zeeman, Samuel C</p> <p>2015-01-01</p> <p>Photosynthetic assimilation of carbon is a defining feature of the plant kingdom. The fixation of large amounts of carbon dioxide supports the synthesis of carbohydrates, which make up the bulk of plant biomass. Exact measurements of carbon assimilation rates are therefore crucial due to their impact on the plants metabolism, growth and reproductive success. Commercially available single-leaf cuvettes allow the detailed analysis of many photosynthetic parameters, including <span class="hlt">gas</span> <span class="hlt">exchange</span>, of a selected leaf area. However, these cuvettes can be difficult to use with small herbaceous plants such as Arabidopsis thaliana or plants having delicate or textured leaves. Furthermore, data from single leaves can be difficult to scale-up for a plant shoot with a complex architecture and tissues in different physiological states. Therefore, we constructed a versatile system-EGES-1-to simultaneously measure <span class="hlt">gas</span> <span class="hlt">exchange</span> in the whole shoots of multiple individual plants. Our system was designed to be able record data continuously over several days. The EGES-1 system yielded comparable measurements for eight plants for up to 6 days in stable, physiologically realistic conditions. The chambers seals have negligible permeability to carbon dioxide and the system is designed so as to detect any bulk-flow air leaks. We show that the system can be used to monitor plant responses to changing environmental conditions, such as changes in illumination or stress treatments, and to compare plants with phenotypically severe mutations. By incorporating interchangeable lids, the system could be used to measure photosynthetic <span class="hlt">gas</span> <span class="hlt">exchange</span> in several genera such as Arabidopsis, Nicotiana, Pisum, Lotus and Mesembryanthemum. EGES-1 can be introduced into a variety of growth facilities and measure <span class="hlt">gas</span> <span class="hlt">exchange</span> in the shoots diverse plant species grown in different growth media. It is ideal for comparing photosynthetic carbon assimilation of wild-type and mutant plants and/or plants undergoing</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17867654','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17867654"><span>Oligonucleotide <span class="hlt">gas</span>-phase hydrogen/deuterium <span class="hlt">exchange</span> with D2S in the collision cell of a quadrupole-Fourier transform ion cyclotron resonance mass spectrometer.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mo, Jingjie; Håkansson, Kristina</p> <p>2007-10-15</p> <p>We have implemented <span class="hlt">gas</span>-phase hydrogen/deuterium <span class="hlt">exchange</span> (HDX) experiments in the external collision cell of a hybrid quadrupole-Fourier transform ion cyclotron resonance mass spectrometer. In this configuration, multiply charged oligonucleotide anions undergo significant <span class="hlt">exchange</span> with D(2)S at reaction intervals ranging from 0.11 to 60.1 s. For DNA homohexamers, relative <span class="hlt">exchange</span> rates were dC(6) approximately dA(6) > dG(6) > dT(6), correlating with the <span class="hlt">gas</span>-phase acidities of nucleobases (C > A > T > G), except for guanine. Our results are consistent with a relay mechanism in which D(2)S interacts with both a backbone phosphate group and a neutral nucleobase through hydrogen bonding. We propose that the faster <span class="hlt">exchange</span> of polyguanosine compared to polythymidine is due to the larger size of guanine and the orientation of its labile hydrogens, which may result in <span class="hlt">gas</span>-phase conformations more favorable for forming complexes with D(2)S. Similar trends were observed for RNA homohexamers, although their HDX rates were faster than for DNA, suggesting they can also <span class="hlt">exchange</span> via another relay process involving the 2'-hydroxyl group. HDX of DNA duplexes further supports the involvement of nucleobase hydrogens because duplexes <span class="hlt">exchanged</span> slower than their corresponding single strands, presumably due to the intermolecular hydrogen bonds between nucleobases. This work constitutes the first investigation of the mechanisms of oligonucleotide <span class="hlt">gas</span>-phase HDX. Our results on duplexes show promise for application of this strategy to the characterization of structured nucleic acids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ACPD...1313285B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ACPD...1313285B"><span>Air/sea DMS <span class="hlt">gas</span> transfer in the North Atlantic: evidence for limited interfacial <span class="hlt">gas</span> <span class="hlt">exchange</span> at high wind speed</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bell, T. G.; De Bruyn, W.; Miller, S. D.; Ward, B.; Christensen, K.; Saltzman, E. S.</p> <p>2013-05-01</p> <p>Shipboard measurements of eddy covariance DMS air/sea fluxes and seawater concentration were carried out in the North Atlantic bloom region in June/July 2011. <span class="hlt">Gas</span> transfer coefficients (k660) show a linear dependence on mean horizontal wind speed at wind speeds up to 11 m s-1. At higher wind speeds the relationship between k660 and wind speed weakens. At high winds, measured DMS fluxes were lower than predicted based on the linear relationship between wind speed and interfacial stress extrapolated from low to intermediate wind speeds. In contrast, the transfer coefficient for sensible heat did not exhibit this effect. The apparent suppression of air/sea <span class="hlt">gas</span> flux at higher wind speeds appears to be related to sea state, as determined from shipboard wave measurements. These observations are consistent with the idea that long waves suppress near surface water side turbulence, and decrease interfacial <span class="hlt">gas</span> transfer. This effect may be more easily observed for DMS than for less soluble gases, such as CO2, because the air/sea <span class="hlt">exchange</span> of DMS is controlled by interfacial rather than bubble-mediated <span class="hlt">gas</span> transfer under high wind speed conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMEP43D0770P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMEP43D0770P"><span>Wind driven vertical transport in a vegetated, wetland water column with air-water <span class="hlt">gas</span> <span class="hlt">exchange</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Poindexter, C.; Variano, E. A.</p> <p>2010-12-01</p> <p>Flow around arrays of cylinders at low and intermediate Reynolds numbers has been studied numerically, analytically and experimentally. Early results demonstrated that at flow around randomly oriented cylinders exhibits reduced turbulent length scales and reduced diffusivity when compared to similarly forced, unimpeded flows (Nepf 1999). While horizontal dispersion in flows through cylinder arrays has received considerable research attention, the case of vertical dispersion of reactive constituents has not. This case is relevant to the vertical transfer of dissolved gases in wetlands with emergent vegetation. We present results showing that the presence of vegetation can significantly enhance vertical transport, including <span class="hlt">gas</span> transfer across the air-water interface. Specifically, we study a wind-sheared air-water interface in which randomly arrayed cylinders represent emergent vegetation. Wind is one of several processes that may govern physical dispersion of dissolved gases in wetlands. Wind represents the dominant force for <span class="hlt">gas</span> transfer across the air-water interface in the ocean. Empirical relationships between wind and the <span class="hlt">gas</span> transfer coefficient, k, have been used to estimate spatial variability of CO2 <span class="hlt">exchange</span> across the worlds’ oceans. Because wetlands with emergent vegetation are different from oceans, different model of wind effects is needed. We investigated the vertical transport of dissolved oxygen in a scaled wetland model built inside a laboratory tank equipped with an open-ended wind tunnel. Plastic tubing immersed in water to a depth of approximately 40 cm represented emergent vegetation of cylindrical form such as hard-stem bulrush (Schoenoplectus acutus). After partially removing the oxygen from the tank water via reaction with sodium sulfite, we used an optical probe to measure dissolved oxygen at mid-depth as the tank water re-equilibrated with the air above. We used dissolved oxygen time-series for a range of mean wind speeds to estimate the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=262549','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=262549"><span>Quantifying the measurement errors in a LI-6400 <span class="hlt">gas</span> <span class="hlt">exchange</span> system and their effects on the parameterization of Farquhar et al. model for C3 leaves</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>The LI-6400 <span class="hlt">gas</span> <span class="hlt">exchange</span> system (Li-Cor, Inc, Lincoln, NE, USA) has been widely used for the measurement of net <span class="hlt">gas</span> <span class="hlt">exchanges</span> and calibration/parameterization of leaf models. Measurement errors due to diffusive leakages of water vapor and carbon dioxide between inside and outside of the leaf chamber...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21692813','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21692813"><span>Responses to water stress of <span class="hlt">gas</span> <span class="hlt">exchange</span> and metabolites in Eucalyptus and Acacia spp.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Warren, Charles R; Aranda, Ismael; Cano, F Javier</p> <p>2011-10-01</p> <p>Studies of water stress commonly examine either <span class="hlt">gas</span> <span class="hlt">exchange</span> or leaf metabolites, and many fail to quantify the concentration of CO₂ in the chloroplasts (C(c)). We redress these limitations by quantifying C(c) from discrimination against ¹³CO₂ and using <span class="hlt">gas</span> chromatography-mass spectrometry (GC-MS) for leaf metabolite profiling. Five Eucalyptus and two Acacia species from semi-arid to mesic habitats were subjected to a 2 month water stress treatment (Ψ(pre-dawn) = -1.7 to -2.3 MPa). Carbohydrates dominated the leaf metabolite profiles of species from dry areas, whereas organic acids dominated the metabolite profiles of species from wet areas. Water stress caused large decreases in photosynthesis and C(c), increases in 17-33 metabolites and decreases in 0-9 metabolites. In most species, fructose, glucose and sucrose made major contributions to osmotic adjustment. In Acacia, significant osmotic adjustment was also caused by increases in pinitol, pipecolic acid and trans-4-hydroxypipecolic acid. There were also increases in low-abundance metabolites (e.g. proline and erythritol), and metabolites that are indicative of stress-induced changes in metabolism [e.g. γ-aminobutyric acid (GABA) shunt, photorespiration, phenylpropanoid pathway]. The response of <span class="hlt">gas</span> <span class="hlt">exchange</span> to water stress and rewatering is rather consistent among species originating from mesic to semi-arid habitats, and the general response of metabolites to water stress is rather similar, although the specific metabolites involved may vary. © 2011 Blackwell Publishing Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/2676345','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/2676345"><span>Measurement of <span class="hlt">gas</span> <span class="hlt">exchange</span> in intensive care: laboratory and clinical validation of a new device.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Takala, J; Keinänen, O; Väisänen, P; Kari, A</p> <p>1989-10-01</p> <p>The performance of a new <span class="hlt">gas</span> <span class="hlt">exchange</span> monitor was assessed both in laboratory simulation and in ICU patients. Laboratory simulation using N2 and CO2 injections resulted in a mean error of 2 +/- 2% in CO2 production (VCO2) and 4 +/- 4% in oxygen consumption (VO2) in respirator measurements (n = 55) and in a mean error of 3 +/- 2% in VCO2 and 4 +/- 2% in VO2 in canopy measurements (n = 25). The mean error in RQ during ethanol burning was 2 +/- 2% in respirator measurements (n = 45) and 1 +/- 1% in canopy measurements. FIO2 had little effect on the accuracy of VCO2, whereas the accuracy on high rates of VO2 (VO2 = 400 ml/min) was reduced, when FIO2 increased: the error ranged from 1 +/- 1% to 6 +/- 1%, except at VO2 400 ml/min during FIO2 0.8, where the error was 16 +/- 3%. Neither peak airway pressure (+13 to +63 cm H2O) nor PEEP (0 to +20 cm H2O) had an effect on the accuracy. The highest level of minute ventilation studied (22.5 L/min) reduced the accuracy slightly (mean error of VCO2 4 +/- 1% and VO2 7 +/- 2%). In patients during controlled mechanical ventilation, increasing FIO2 from 0.4 to 0.6 had no effect on the results. VO2 was consistently higher by <span class="hlt">gas</span> <span class="hlt">exchange</span> than by the Fick principle: 16 +/- 9% during controlled ventilation (n = 20), 21 +/- 8% on synchronized intermittent mandatory ventilation (n = 10) and 25 +/- 8% during spontaneous breathing. We conclude that the device proved to be accurate for <span class="hlt">gas</span> <span class="hlt">exchange</span> measurements in the ICU.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18417636','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18417636"><span>Three-dimensional <span class="hlt">gas</span> <span class="hlt">exchange</span> pathways in pome fruit characterized by synchrotron x-ray computed tomography.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Verboven, Pieter; Kerckhofs, Greet; Mebatsion, Hibru Kelemu; Ho, Quang Tri; Temst, Kristiaan; Wevers, Martine; Cloetens, Peter; Nicolaï, Bart M</p> <p>2008-06-01</p> <p>Our understanding of the <span class="hlt">gas</span> <span class="hlt">exchange</span> mechanisms in plant organs critically depends on insights in the three-dimensional (3-D) structural arrangement of cells and voids. Using synchrotron radiation x-ray tomography, we obtained for the first time high-contrast 3-D absorption images of in vivo fruit tissues of high moisture content at 1.4-microm resolution and 3-D phase contrast images of cell assemblies at a resolution as low as 0.7 microm, enabling visualization of individual cell morphology, cell walls, and entire void networks that were previously unknown. Intercellular spaces were always clear of water. The apple (Malus domestica) cortex contains considerably larger parenchyma cells and voids than pear (Pyrus communis) parenchyma. Voids in apple often are larger than the surrounding cells and some cells are not connected to void spaces. The main voids in apple stretch hundreds of micrometers but are disconnected. Voids in pear cortex tissue are always smaller than parenchyma cells, but each cell is surrounded by a tight and continuous network of voids, except near brachyssclereid groups. Vascular and dermal tissues were also measured. The visualized network architecture was consistent over different picking dates and shelf life. The differences in void fraction (5.1% for pear cortex and 23.0% for apple cortex) and in <span class="hlt">gas</span> network architecture helps explain the ability of tissues to facilitate or impede <span class="hlt">gas</span> <span class="hlt">exchange</span>. Structural changes and anisotropy of tissues may eventually lead to physiological disorders. A combined tomography and internal <span class="hlt">gas</span> analysis during growth are needed to make progress on the understanding of void formation in fruit.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1439032','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1439032"><span><span class="hlt">Gas</span> Retention, <span class="hlt">Gas</span> Release, and Fluidization of Spherical Resorcinol-Formaldehyde (sRF) Ion <span class="hlt">Exchange</span> Resin</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Gauglitz, Phillip A.; Rassat, Scot D.; Linn, Diana</p> <p></p> <p>The Low-Activity Waste Pretreatment System (LAWPS) is being developed to provide treated supernatant liquid from the Hanford tank farms directly to the Low-Activity Waste (LAW) Vitrification Facility at the Hanford Tank Waste Treatment and Immobilization Plant. The design and development of the LAWPS is being conducted by Washington River Protection Solutions, LLC. A key process in LAWPS is the removal of radioactive Cs in ion <span class="hlt">exchange</span> (IX) columns filled with spherical resorcinol-formaldehyde (sRF) resin. When loaded with radioactive Cs, radiolysis of water in the LAW liquid will generate hydrogen <span class="hlt">gas</span>. In normal operations, the generated hydrogen is expected to remainmore » dissolved in the liquid and be continuously removed by liquid flow. One accident scenario being evaluated is the loss of liquid flow through the sRF resin bed after it has been loaded with radioactive Cs and hydrogen <span class="hlt">gas</span> is being generated by radiolysis. For an accident scenario with a loss of flow, hydrogen <span class="hlt">gas</span> can be retained within the IX column both in the sRF resin bed and below the bottom screen that supports the resin within the column, which creates a hydrogen flammability hazard. Because there is a potential for a large fraction of the retained hydrogen to be released over a short duration as a <span class="hlt">gas</span> release event, there is a need to quantify the size and rate of potential <span class="hlt">gas</span> release events. Due to the potential for a large, rapid <span class="hlt">gas</span> release event, an evaluation of mitigation methods to eliminate the hydrogen hazard is also needed. One method being considered for mitigating the hydrogen hazard during a loss of flow accident is to have a secondary flow system, with two redundant pumps operating in series, that re-circulates liquid upwards through the bed and into a vented break tank where hydrogen <span class="hlt">gas</span> is released from the liquid and removed by venting the headspace of the break tank. The mechanism for inducing release of <span class="hlt">gas</span> from the sRF bed is to fluidize the bed, which should allow</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18640753','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18640753"><span>Dry deposition and soil-air <span class="hlt">gas</span> <span class="hlt">exchange</span> of polychlorinated biphenyls (PCBs) in an industrial area.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bozlaker, Ayse; Odabasi, Mustafa; Muezzinoglu, Aysen</p> <p>2008-12-01</p> <p>Ambient air and dry deposition, and soil samples were collected at the Aliaga industrial site in Izmir, Turkey. Atmospheric total (particle+<span class="hlt">gas</span>) Sigma(41)-PCB concentrations were higher in summer (3370+/-1617 pg m(-3), average+SD) than in winter (1164+/-618 pg m(-3)), probably due to increased volatilization with temperature. Average particulate Sigma(41)-PCBs dry deposition fluxes were 349+/-183 and 469+/-328 ng m(-2) day(-1) in summer and winter, respectively. Overall average particulate deposition velocity was 5.5+/-3.5 cm s(-1). The spatial distribution of Sigma(41)-PCB soil concentrations (n=48) showed that the iron-steel plants, ship dismantling facilities, refinery and petrochemicals complex are the major sources in the area. Calculated air-soil <span class="hlt">exchange</span> fluxes indicated that the contaminated soil is a secondary source to the atmosphere for lighter PCBs and as a sink for heavier ones. Comparable magnitude of <span class="hlt">gas</span> <span class="hlt">exchange</span> and dry particle deposition fluxes indicated that both mechanisms are equally important for PCB movement between air and soil in Aliaga.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70179681','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70179681"><span>The Iġnik Sikumi Field Experiment, Alaska North Slope: Design, operations, and implications for CO2−CH4 <span class="hlt">exchange</span> in <span class="hlt">gas</span> hydrate reservoirs</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Boswell, Ray; Schoderbek, David; Collett, Timothy S.; Ohtsuki, Satoshi; White, Mark; Anderson, Brian J.</p> <p>2017-01-01</p> <p>The Iġnik Sikumi <span class="hlt">Gas</span> Hydrate <span class="hlt">Exchange</span> Field Experiment was conducted by ConocoPhillips in partnership with the U.S. Department of Energy, the Japan Oil, <span class="hlt">Gas</span> and Metals National Corporation, and the U.S. Geological Survey within the Prudhoe Bay Unit on the Alaska North Slope during 2011 and 2012. The primary goals of the program were to (1) determine the feasibility of <span class="hlt">gas</span> injection into hydrate-bearing sand reservoirs and (2) observe reservoir response upon subsequent flowback in order to assess the potential for CO2 <span class="hlt">exchange</span> for CH4 in naturally occurring <span class="hlt">gas</span> hydrate reservoirs. Initial modeling determined that no feasible means of injection of pure CO2 was likely, given the presence of free water in the reservoir. Laboratory and numerical modeling studies indicated that the injection of a mixture of CO2 and N2 offered the best potential for <span class="hlt">gas</span> injection and <span class="hlt">exchange</span>. The test featured the following primary operational phases: (1) injection of a gaseous phase mixture of CO2, N2, and chemical tracers; (2) flowback conducted at downhole pressures above the stability threshold for native CH4 hydrate; and (3) an extended (30-days) flowback at pressures near, and then below, the stability threshold of native CH4 hydrate. The test findings indicate that the formation of a range of mixed-<span class="hlt">gas</span> hydrates resulted in a net <span class="hlt">exchange</span> of CO2 for CH4 in the reservoir, although the complexity of the subsurface environment renders the nature, extent, and efficiency of the <span class="hlt">exchange</span> reaction uncertain. The next steps in the evaluation of <span class="hlt">exchange</span> technology should feature multiple well applications; however, such field test programs will require extensive preparatory experimental and numerical modeling studies and will likely be a secondary priority to further field testing of production through depressurization. Additional insights gained from the field program include the following: (1) <span class="hlt">gas</span> hydrate destabilization is self-limiting, dispelling any notion of the potential for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25923517','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25923517"><span>An Excel tool for deriving key photosynthetic parameters from combined <span class="hlt">gas</span> <span class="hlt">exchange</span> and chlorophyll fluorescence: theory and practice.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bellasio, Chandra; Beerling, David J; Griffiths, Howard</p> <p>2016-06-01</p> <p>Combined photosynthetic <span class="hlt">gas</span> <span class="hlt">exchange</span> and modulated fluorometres are widely used to evaluate physiological characteristics associated with phenotypic and genotypic variation, whether in response to genetic manipulation or resource limitation in natural vegetation or crops. After describing relatively simple experimental procedures, we present the theoretical background to the derivation of photosynthetic parameters, and provide a freely available Excel-based fitting tool (EFT) that will be of use to specialists and non-specialists alike. We use data acquired in concurrent variable fluorescence-<span class="hlt">gas</span> <span class="hlt">exchange</span> experiments, where A/Ci and light-response curves have been measured under ambient and low oxygen. From these data, the EFT derives light respiration, initial PSII (photosystem II) photochemical yield, initial quantum yield for CO2 fixation, fraction of incident light harvested by PSII, initial quantum yield for electron transport, electron transport rate, rate of photorespiration, stomatal limitation, Rubisco (ribulose 1·5-bisphosphate carboxylase/oxygenase) rate of carboxylation and oxygenation, Rubisco specificity factor, mesophyll conductance to CO2 diffusion, light and CO2 compensation point, Rubisco apparent Michaelis-Menten constant, and Rubisco CO2 -saturated carboxylation rate. As an example, a complete analysis of <span class="hlt">gas</span> <span class="hlt">exchange</span> data on tobacco plants is provided. We also discuss potential measurement problems and pitfalls, and suggest how such empirical data could subsequently be used to parameterize predictive photosynthetic models. © 2015 John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1049260','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1049260"><span>Optimizing Ventilation Distribution and <span class="hlt">Gas</span> <span class="hlt">Exchange</span> in Combat-Related Lung Injury Using Multifrequency Oscillation</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2017-10-01</p> <p><span class="hlt">gas</span> <span class="hlt">exchange</span> in the acute respiratory distress syndrome (ARDS) and other forms of combat-related lung injury, while simultaneously preserving mechanical...civilian populations with ARDS. 15. SUBJECT TERMS Acute lung injury, Acute respiratory distress syndrome , Blast lung injury, Combat-related lung injury...REFERENCES 18 10.0 APPENDICES 19 Page 4 1.0 INTRODUCTION Respiratory failure from acute lung injury, now termed the acute respiratory distress syndrome</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MS%26E..357a2024Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MS%26E..357a2024Z"><span>Thermodynamic properties of <span class="hlt">gas</span>-condensate system with <span class="hlt">abnormally</span> high content of heavy hydrocarbons</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zanochuev, S. A.; Shabarov, A. B.; Podorozhnikov, S. Yu; Zakharov, A. A.</p> <p>2018-05-01</p> <p><span class="hlt">Gas</span>-condensate systems (GCS) with an <span class="hlt">abnormally</span> high content of heavy hydrocarbons are characterized by a sharp change in both phase and component compositions with an insignificant decrease in pressure below the start pressure of the phase transitions (the beginning of condensation). Calculation methods for describing the phase behavior of such systems are very sensitive to the quality of the initial information. The uncertainty of the input data leads not only to significant errors in the forecast of phase compositions, but also to an incorrect phase state estimation of the whole system. The research presents the experimental thermodynamic parameters of the GCS of the BT reservoirs on the Beregovoye field, obtained at the phase equilibrium facility. The data contribute to the adaptation of the calculated models of the phase behavior of the GCS with a change in pressure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoRL..43.3813H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..43.3813H"><span>Influence of current velocity and wind speed on air-water <span class="hlt">gas</span> <span class="hlt">exchange</span> in a mangrove estuary</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ho, David T.; Coffineau, Nathalie; Hickman, Benjamin; Chow, Nicholas; Koffman, Tobias; Schlosser, Peter</p> <p>2016-04-01</p> <p>Knowledge of air-water <span class="hlt">gas</span> transfer velocities and water residence times is necessary to study the fate of mangrove derived carbon exported into surrounding estuaries and ultimately to determine carbon balances in mangrove ecosystems. For the first time, the 3He/SF6 dual tracer technique, which has been proven to be a powerful tool to determine <span class="hlt">gas</span> transfer velocities in the ocean, is applied to Shark River, an estuary situated in the largest contiguous mangrove forest in North America. The mean <span class="hlt">gas</span> transfer velocity was 3.3 ± 0.2 cm h-1 during the experiment, with a water residence time of 16.5 ± 2.0 days. We propose a <span class="hlt">gas</span> <span class="hlt">exchange</span> parameterization that takes into account the major sources of turbulence in the estuary (i.e., bottom generated shear and wind stress).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/49903','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/49903"><span>Linking nonstructural carbohydrate dynamics to <span class="hlt">gas</span> <span class="hlt">exchange</span> and leaf hydraulic behavior in Pinus edulis and Juniperus monosperma</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>David R. Woodruff; Frederick C. Meinzer; Danielle E. Marias; Sanna Sevanto; Michael W. Jenkins; Nate G. McDowell</p> <p>2014-01-01</p> <p>Leaf hydraulics, <span class="hlt">gas</span> <span class="hlt">exchange</span> and carbon storage in Pinus edulis and Juniperus monosperma, two tree species on opposite ends of the isohydry–anisohydry spectrum, were analyzed to examine relationships between hydraulic function and carbohydrate dynamics.Leaf hydraulic vulnerability,...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16827010','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16827010"><span>Homeostatic maintenance of ponderosa pine <span class="hlt">gas</span> <span class="hlt">exchange</span> in response to stand density changes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McDowell, Nate G; Adams, Henry D; Bailey, John D; Hess, Marcey; Kolb, Thomas E</p> <p>2006-06-01</p> <p>Homeostatic maintenance of <span class="hlt">gas</span> <span class="hlt">exchange</span> optimizes carbon gain per water loss. Homeostasis is regulated by short-term physiological and long-term structural mechanisms, both of which may respond to changes in resource availability associated with competition. Therefore, stand density regulation via silvicultural manipulations may facilitate growth and survival through mechanisms operating at both short and long timescales. We investigated the responses of ponderosa pine (Pinus ponderosa) to stand basal area manipulations in Arizona, USA. Stand basal area was manipulated to seven replicated levels in 1962 and was maintained for four decades by decadal thinning. We measured basal area increment (BAI) to assess the response and sustainability of wood growth, carbon isotope discrimination (A) inferred from annual rings to assess the response of crown <span class="hlt">gas</span> <span class="hlt">exchange</span>, and ratios of leaf area to sapwood area (A(l):A(s)) to assess longer term structural acclimation. Basal area treatments increased soil water potential (r2 = 0.99) but did not affect photosynthetic capacity. BAI increased within two years of thinning, and the 40-year mean BAI was negatively correlated with stand basal area (r2 = 0.98). delta was negatively correlated with stand basal area for years 5 through 12 after thinning (r2 = 0.90). However, delta was relatively invariant with basal area for the period 13-40 years after initial thinning despite maintenance of treatment basal areas via repeated decadal thinnings. Independent <span class="hlt">gas</span> <span class="hlt">exchange</span> measurements verified that the ratio of photosynthesis to stomatal conductance was invariant with basal area, but absolute values of both were elevated at lower basal areas. A(l):A(s) was negatively correlated with basal area (r2 = 0.93). We hypothesize that increased A(l):A(s) is a homeostatic response to increased water availability that maximizes water-use efficiency and whole-tree carbon uptake. Elevated A(l):A(s) of trees at low basal areas was associated with greater</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AIPC.1149..833K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AIPC.1149..833K"><span>Optical Pumping Spin <span class="hlt">Exchange</span> 3He <span class="hlt">Gas</span> Cells for Magnetic Resonance Imaging</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, W.; Stepanyan, S. S.; Kim, A.; Jung, Y.; Woo, S.; Yurov, M.; Jang, J.</p> <p>2009-08-01</p> <p>We present a device for spin-<span class="hlt">exchange</span> optical pumping system to produce large quantities of polarized noble gases for Magnetic Resonance Imaging (MRI). A method and design of apparatus for pumping the polarization of noble gases is described. The method and apparatus enable production, storage and usage of hyperpolarized noble gases for different purposes, including Magnetic Resonance Imaging of human and animal subjects. Magnetic imaging agents breathed into lungs can be observed by the radio waves of the MRI scanner and report back physical and functional information about lung's health and desease. The technique known as spin <span class="hlt">exchange</span> optical pumping is used. Nuclear magnetic resonance is implemented to measure the polarization of hyperpolarized <span class="hlt">gas</span>. The cells prepared and sealed under high vacuum after handling Alkali metals into the cell and filling with the 3He-N2 mixture. The cells could be refilled. The 3He reaches around 50% polarization in 5-15 hours.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23844085','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23844085"><span>Plant water use efficiency over geological time--evolution of leaf stomata configurations affecting plant <span class="hlt">gas</span> <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Assouline, Shmuel; Or, Dani</p> <p>2013-01-01</p> <p>Plant <span class="hlt">gas</span> <span class="hlt">exchange</span> is a key process shaping global hydrological and carbon cycles and is often characterized by plant water use efficiency (WUE - the ratio of CO2 gain to water vapor loss). Plant fossil record suggests that plant adaptation to changing atmospheric CO2 involved correlated evolution of stomata density (d) and size (s), and related maximal aperture, amax . We interpreted the fossil record of s and d correlated evolution during the Phanerozoic to quantify impacts on <span class="hlt">gas</span> conductance affecting plant transpiration, E, and CO2 uptake, A, independently, and consequently, on plant WUE. A shift in stomata configuration from large s-low d to small s-high d in response to decreasing atmospheric CO2 resulted in large changes in plant <span class="hlt">gas</span> <span class="hlt">exchange</span> characteristics. The relationships between <span class="hlt">gas</span> conductance, gws , A and E and maximal relative transpiring leaf area, (amax ⋅d), exhibited hysteretic-like behavior. The new WUE trend derived from independent estimates of A and E differs from established WUE-CO2 trends for atmospheric CO2 concentrations exceeding 1,200 ppm. In contrast with a nearly-linear decrease in WUE with decreasing CO2 obtained by standard methods, the newly estimated WUE trend exhibits remarkably stable values for an extended geologic period during which atmospheric CO2 dropped from 3,500 to 1,200 ppm. Pending additional tests, the findings may affect projected impacts of increased atmospheric CO2 on components of the global hydrological cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Cryo...64..207S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Cryo...64..207S"><span>Operation of an ADR using helium <span class="hlt">exchange</span> <span class="hlt">gas</span> as a substitute for a failed heat switch</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shirron, P.; DiPirro, M.; Kimball, M.; Sneiderman, G.; Porter, F. S.; Kilbourne, C.; Kelley, R.; Fujimoto, R.; Yoshida, S.; Takei, Y.; Mitsuda, K.</p> <p>2014-11-01</p> <p>The Soft X-ray Spectrometer (SXS) is one of four instruments on the Japanese Astro-H mission, which is currently planned for launch in late 2015. The SXS will perform imaging spectroscopy in the soft X-ray band (0.3-12 keV) using a 6 × 6 pixel array of microcalorimeters cooled to 50 mK. The detectors are cooled by a 3-stage adiabatic demagnetization refrigerator (ADR) that rejects heat to either a superfluid helium tank (at 1.2 K) or to a 4.5 K Joule-Thomson (JT) cryocooler. Four <span class="hlt">gas</span>-gap heat switches are used in the assembly to manage heat flow between the ADR stages and the heat sinks. The engineering model (EM) ADR was assembled and performance tested at NASA/GSFC in November 2011, and subsequently installed in the EM dewar at Sumitomo Heavy Industries, Japan. During the first cooldown in July 2012, a failure of the heat switch that linked the two colder stages of the ADR to the helium tank was observed. Operation of the ADR requires some mechanism for thermally linking the salt pills to the heat sink, and then thermally isolating them. With the failed heat switch unable to perform this function, an alternate plan was devised which used carefully controlled amounts of <span class="hlt">exchange</span> <span class="hlt">gas</span> in the dewar's guard vacuum to facilitate heat <span class="hlt">exchange</span>. The process was successfully demonstrated in November 2012, allowing the ADR to cool the detectors to 50 mK for hold times in excess of 10 h. This paper describes the <span class="hlt">exchange-gas</span>-assisted recycling process, and the strategies used to avoid helium contamination of the detectors at low temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150010114','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150010114"><span>Operation of an ADR Using Helium <span class="hlt">Exchange</span> <span class="hlt">Gas</span> as a Substitute for a Failed Heat Switch</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shirron, P.; DiPirro, M.; Kimball, M.; Sneiderman, G.; Porter, F. S.; Kilbourne, C.; Kelley, R.; Fujimoto, R.; Yoshida, S.; Takei, Y.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20150010114'); toggleEditAbsImage('author_20150010114_show'); toggleEditAbsImage('author_20150010114_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20150010114_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20150010114_hide"></p> <p>2014-01-01</p> <p>The Soft X-ray Spectrometer (SXS) is one of four instruments on the Japanese Astro-H mission, which is currently planned for launch in late 2015. The SXS will perform imaging spectroscopy in the soft X-ray band (0.3-12 keV) using a 6 6 pixel array of microcalorimeters cooled to 50 mK. The detectors are cooled by a 3-stage adiabatic demagnetization refrigerator (ADR) that rejects heat to either a superfluid helium tank (at 1.2 K) or to a 4.5 K Joule-Thomson (JT) cryocooler. Four <span class="hlt">gas</span>-gap heat switches are used in the assembly to manage heat flow between the ADR stages and the heat sinks. The engineering model (EM) ADR was assembled and performance tested at NASA/GSFC in November 2011, and subsequently installed in the EM dewar at Sumitomo Heavy Industries, Japan. During the first cooldown in July 2012, a failure of the heat switch that linked the two colder stages of the ADR to the helium tank was observed. Operation of the ADR requires some mechanism for thermally linking the salt pills to the heat sink, and then thermally isolating them. With the failed heat switch unable to perform this function, an alternate plan was devised which used carefully controlled amounts of <span class="hlt">exchange</span> <span class="hlt">gas</span> in the dewar's guard vacuum to facilitate heat <span class="hlt">exchange</span>. The process was successfully demonstrated in November 2012, allowing the ADR to cool the detectors to 50 mK for hold times in excess of 10 h. This paper describes the <span class="hlt">exchange-gas</span>-assisted recycling process, and the strategies used to avoid helium contamination of the detectors at low temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ACP....1311073B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ACP....1311073B"><span>Air-sea dimethylsulfide (DMS) <span class="hlt">gas</span> transfer in the North Atlantic: evidence for limited interfacial <span class="hlt">gas</span> <span class="hlt">exchange</span> at high wind speed</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bell, T. G.; De Bruyn, W.; Miller, S. D.; Ward, B.; Christensen, K.; Saltzman, E. S.</p> <p>2013-11-01</p> <p>Shipboard measurements of eddy covariance dimethylsulfide (DMS) air-sea fluxes and seawater concentration were carried out in the North Atlantic bloom region in June/July 2011. <span class="hlt">Gas</span> transfer coefficients (k660) show a linear dependence on mean horizontal wind speed at wind speeds up to 11 m s-1. At higher wind speeds the relationship between k660 and wind speed weakens. At high winds, measured DMS fluxes were lower than predicted based on the linear relationship between wind speed and interfacial stress extrapolated from low to intermediate wind speeds. In contrast, the transfer coefficient for sensible heat did not exhibit this effect. The apparent suppression of air-sea <span class="hlt">gas</span> flux at higher wind speeds appears to be related to sea state, as determined from shipboard wave measurements. These observations are consistent with the idea that long waves suppress near-surface water-side turbulence, and decrease interfacial <span class="hlt">gas</span> transfer. This effect may be more easily observed for DMS than for less soluble gases, such as CO2, because the air-sea <span class="hlt">exchange</span> of DMS is controlled by interfacial rather than bubble-mediated <span class="hlt">gas</span> transfer under high wind speed conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010BGeo....7..121A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010BGeo....7..121A"><span>From biota to chemistry and climate: towards a comprehensive description of trace <span class="hlt">gas</span> <span class="hlt">exchange</span> between the biosphere and atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arneth, A.; Sitch, S.; Bondeau, A.; Butterbach-Bahl, K.; Foster, P.; Gedney, N.; de Noblet-Ducoudré, N.; Prentice, I. C.; Sanderson, M.; Thonicke, K.; Wania, R.; Zaehle, S.</p> <p>2010-01-01</p> <p><span class="hlt">Exchange</span> of non-CO2 trace gases between the land surface and the atmosphere plays an important role in atmospheric chemistry and climate. Recent studies have highlighted its importance for interpretation of glacial-interglacial ice-core records, the simulation of the pre-industrial and present atmosphere, and the potential for large climate-chemistry and climate-aerosol feedbacks in the coming century. However, spatial and temporal variations in trace <span class="hlt">gas</span> emissions and the magnitude of future feedbacks are a major source of uncertainty in atmospheric chemistry, air quality and climate science. To reduce such uncertainties Dynamic Global Vegetation Models (DGVMs) are currently being expanded to mechanistically represent processes relevant to non-CO2 trace <span class="hlt">gas</span> <span class="hlt">exchange</span> between land biota and the atmosphere. In this paper we present a review of important non-CO2 trace <span class="hlt">gas</span> emissions, the state-of-the-art in DGVM modelling of processes regulating these emissions, identify key uncertainties for global scale model applications, and discuss a methodology for model integration and evaluation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009BGD.....6.7717A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009BGD.....6.7717A"><span>From biota to chemistry and climate: towards a comprehensive description of trace <span class="hlt">gas</span> <span class="hlt">exchange</span> between the biosphere and atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arneth, A.; Sitch, S.; Bondeau, A.; Butterbach-Bahl, K.; Foster, P.; Gedney, N.; de Noblet-Ducoudré, N.; Prentice, I. C.; Sanderson, M.; Thonicke, K.; Wania, R.; Zaehle, S.</p> <p>2009-07-01</p> <p><span class="hlt">Exchange</span> of non-CO2 trace gases between the land surface and the atmosphere plays an important role in atmospheric chemistry and climate. Recent studies have highlighted its importance for interpretation of glacial-interglacial ice-core records, the simulation of the pre-industrial and present atmosphere, and the potential for large climate-chemistry and climate-aerosol feedbacks in the coming century. However, spatial and temporal variations in trace <span class="hlt">gas</span> emissions and the magnitude of future feedbacks are a major source of uncertainty in atmospheric chemistry, air quality and climate science. To reduce such uncertainties Dynamic Global Vegetation Models (DGVMs) are currently being expanded to mechanistically represent processes relevant to non-CO2 trace <span class="hlt">gas</span> <span class="hlt">exchange</span> between land biota and the atmosphere. In this paper we present a review of important non-CO2 trace <span class="hlt">gas</span> emissions, the state-of-the-art in DGVM modelling of processes regulating these emissions, identify key uncertainties for global scale model applications, and discuss a methodology for model integration and evaluation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Cryo...91..128W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Cryo...91..128W"><span>Experimental study on CO2 frosting and clogging in a brazed plate heat <span class="hlt">exchanger</span> for natural <span class="hlt">gas</span> liquefaction process</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Jitan; He, Tianbiao; Ju, Yonglin</p> <p>2018-04-01</p> <p>The plate-fin heat <span class="hlt">exchanger</span> (PFHE), which has been widely used in natural <span class="hlt">gas</span> liquefaction (LNG) industry at present, has some disadvantages such as being sensitive to the impurities in the feed <span class="hlt">gas</span>, such as water, CO2 and H2S. Compared with the PFHE, the brazed plate heat <span class="hlt">exchanger</span> (BPHE), which has been applied in some boil off <span class="hlt">gas</span> (BOG) recycling LNG plants of small to middle size, has simpler inherent structure and higher impurity tolerance. In this study the BPHE is suggested to replace the PFHE to simplify or even omit the massive CO2 purification equipment for the LNG process. A set of experimental apparatus is designed and constructed to investigate the influence of the CO2 concentration of the natural <span class="hlt">gas</span> on solid precipitation inside a typical BPHE meanly by considering the flow resistance throughout the LNG process. The results show that the maximum allowable CO2 concentration of the natural <span class="hlt">gas</span> liquefied in the BPHE is two orders of magnitude higher than that in the PFHE under the same condition. In addition, the solid-liquid separation for the CO2 impurity is studied and the reasonable separating temperature is obtained. The solid CO2 should be separated below 135 K under the pressure of 3 MPa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=260737','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=260737"><span>Ecosystem Warming Affects Vertical Distribution of Leaf <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Properties and Water Relations of Spring Wheat</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>The vertical distribution of <span class="hlt">gas</span> <span class="hlt">exchange</span> and water relations responses to full-season in situ infrared (IR) warming were evaluated for hard red spring wheat (Triticum aestivum L. cv. Yecora Rojo) grown in an open field in a semiarid desert region of the Southwest USA. A Temperature Free-Air Contro...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880002873','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880002873"><span>Operation of an experimental algal <span class="hlt">gas</span> <span class="hlt">exchanger</span> for use in a CELSS</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smernoff, David T.; Wharton, Robert A., Jr.; Averner, Maurice M.</p> <p>1987-01-01</p> <p>Concepts of a Closed Ecological Life Support System (CELSS) anticipate the use of photosynthetic organisms (higher plants and algae) for air revitalization. The rates of production and uptake of carbon dioxide and oxygen between the crew and the photosynthetic organisms are mismatched. An algal system used for <span class="hlt">gas</span> <span class="hlt">exchange</span> only will have the difficulty of an accumulation or depletion of these gases beyond physiologically tolerable limits (in a closed system the mismatch between assimilatory quotient (AQ) and respiratory quotient (RQ) is balanced by the operation of the waste processor). The results are given of a study designed to test the feasibility of using environmental manipulations to maintain physiologically appropriate atmospheres for algae and mice in a <span class="hlt">gas</span> closed system. Specifically, the atmosphere behavior of this system is considered with algae grown on nitrate or urea and at different light intensities and optical densities. Manipulation of both allow operation of the system in a <span class="hlt">gas</span> stable manner. Operation of such a system in a CELSS may be useful for reduction of buffer sizes, as a backup system for higher plant air revitalization and to supply extra oxygen to the waste processor or during crew changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=315010&Lab=NHEERL&keyword=smith&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=315010&Lab=NHEERL&keyword=smith&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>A dynamic leaf <span class="hlt">gas-exchange</span> strategy is conserved in woody plants under changing ambient CO2: evidence from carbon isotope discrimination in paleo and CO2 enrichment studies</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>Rising atmospheric [CO2], ca, is expected to affect stomatal regulation of leaf <span class="hlt">gas-exchange</span> of woody plants, thus influencing energy fluxes as well as carbon (C), water and nutrient cycling of forests. Researchers have reported that stomata regulate leaf <span class="hlt">gas-exchange</span> around “set...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B23H..05L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B23H..05L"><span>Greenhouse <span class="hlt">Gas</span> <span class="hlt">Exchange</span> in Small Arctic Thaw Ponds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Laurion, I.; Bégin, P. N.; Bouchard, F.; Preskienis, V.</p> <p>2014-12-01</p> <p>Arctic lakes and ponds can represent up to one quarter of the land surface in permafrost landscapes, particularly in lowland tundra landscapes characterized by ice wedge organic polygons. Thaw ponds can be defined as the aquatic ecosystems associated to thawing of organic soils, either resulting from active layer processes and located above low-center peat polygons (hereafter low-center polygonal or LCP ponds), or resulting from thermokarst slumping above melting ice wedges linked to the accelerated degradation of permafrost (hereafter ice-wedge trough or IWT ponds). These ponds can merge together forming larger water bodies, but with relatively stable shores (hereafter merged polygonal or MPG ponds), and with limnological characteristics similar to LCP ponds. These aquatic systems are very small and shallow, and present a different physical structure than the larger thermokarst lakes, generated after years of development and land subsidence. In a glacier valley on Bylot Island, Nunavut, Canada, thermokarst and kettle lakes together represent 29% of the aquatic area, with a thermal profile resembling those of more standard arctic lakes (mixed epilimnion). The IWT ponds (44% of the area) are stratified for a large fraction of the summer despite their shallowness, while LCP and MPG ponds (27% of the area) show a more homogeneous water column. This will affect <span class="hlt">gas</span> <span class="hlt">exchange</span> in these diverse aquatic systems, in addition to their unique microbiota and organic carbon lability that control the production and consumption rates of greenhouse gases. The stratification in IWT ponds generates hypoxic conditions at the bottom, and together with the larger availability of organic carbon, stimulates methanogenesis and limits the mitigating action of methanotrophs. Overall, thaw ponds are largely supersaturated in methane, with IWT ponds dominating the emissions in this landscape (92% of total aquatic emissions estimated for the same valley), and they present large variations in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29366817','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29366817"><span><span class="hlt">Gas</span> <span class="hlt">exchanges</span> in children with cystic fibrosis or primary ciliary dyskinesia: A retrospective study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fuger, Marilyn; Aupiais, Camille; Thouvenin, Guillaume; Taytard, Jessica; Tamalet, Aline; Escudier, Estelle; Boizeau, Priscilla; Corvol, Harriet; Beydon, Nicole</p> <p>2018-05-01</p> <p>Primary ciliary dyskinesia (PCD) and cystic fibrosis (CF) both entail bronchiectasis and pulmonary impairment as measured using spirometry, during childhood. We aimed at looking whether blood <span class="hlt">gas</span> <span class="hlt">exchanges</span> progressed differently between CF and PCD children in a retrospective study of repeated measurements. Comparisons between groups (Wilcoxon-Mann-Whitney and Chi-squared tests) and a mixed linear model, adjusted for age, evaluated associations between diseases and PaO 2 , PaCO 2, or PaO 2- PaCO 2 ratio. Among 42 PCD and 73 CF children, 62% and 59% had respectively bronchiectasis (P = 0.75). Spirometry and blood gases were similar at inclusion (PaO 2 median [IQR] PCD -1.80 [-3.40; -0.40]; CF -1.80 [-4.20; 0.60] z-scores; P = 0.72). PaO 2 and PaO 2 -PaCO 2 ratio similarly and significantly decreased with age in both groups (P < 0.01) whereas PaCO 2 increased more in CF (P = 0.02) remaining within the range of normal (except for one child). To conclude, <span class="hlt">gas</span> <span class="hlt">exchange</span> characteristics, similarly initially impaired in PCD and CF children, tended to less deteriorate with time in PCD children who could benefit from an early diagnosis. Copyright © 2018 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28076413','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28076413"><span>Dynamic Characteristics of Ventilatory and <span class="hlt">Gas</span> <span class="hlt">Exchange</span> during Sinusoidal Walking in Humans.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fukuoka, Yoshiyuki; Iihoshi, Masaaki; Nazunin, Juhelee Tuba; Abe, Daijiro; Fukuba, Yoshiyuki</p> <p>2017-01-01</p> <p>Our present study investigated whether the ventilatory and <span class="hlt">gas</span> <span class="hlt">exchange</span> responses show different dynamics in response to sinusoidal change in cycle work rate or walking speed even if the metabolic demand was equivalent in both types of exercise. Locomotive parameters (stride length and step frequency), breath-by-breath ventilation (V̇E) and <span class="hlt">gas</span> <span class="hlt">exchange</span> (CO2 output (V̇CO2) and O2 uptake (V̇O2)) responses were measured in 10 healthy young participants. The speed of the treadmill was sinusoidally changed between 3 km·h-1 and 6 km·h-1 with various periods (from 10 to 1 min). The amplitude of locomotive parameters against sinusoidal variation showed a constant gain with a small phase shift, being independent of the oscillation periods. In marked contrast, when the periods of the speed oscillations were shortened, the amplitude of V̇E decreased sharply whereas the phase shift of V̇E increased. In comparing walking and cycling at the equivalent metabolic demand, the amplitude of V̇E during sinusoidal walking (SW) was significantly greater than that during sinusoidal cycling (SC), and the phase shift became smaller. The steeper slope of linear regression for the V̇E amplitude ratio to V̇CO2 amplitude ratio was observed during SW than SC. These findings suggested that the greater amplitude and smaller phase shift of ventilatory dynamics were not equivalent between SW and SC even if the metabolic demand was equivalent between both exercises. Such phenomenon would be derived from central command in proportion to locomotor muscle recruitment (feedforward) and muscle afferent feedback.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26286697','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26286697"><span>Deriving C4 photosynthetic parameters from combined <span class="hlt">gas</span> <span class="hlt">exchange</span> and chlorophyll fluorescence using an Excel tool: theory and practice.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bellasio, Chandra; Beerling, David J; Griffiths, Howard</p> <p>2016-06-01</p> <p>The higher photosynthetic potential of C4 plants has led to extensive research over the past 50 years, including C4 -dominated natural biomes, crops such as maize, or for evaluating the transfer of C4 traits into C3 lineages. Photosynthetic <span class="hlt">gas</span> <span class="hlt">exchange</span> can be measured in air or in a 2% Oxygen mixture using readily available commercial <span class="hlt">gas</span> <span class="hlt">exchange</span> and modulated PSII fluorescence systems. Interpretation of these data, however, requires an understanding (or the development) of various modelling approaches, which limit the use by non-specialists. In this paper we present an accessible summary of the theory behind the analysis and derivation of C4 photosynthetic parameters, and provide a freely available Excel Fitting Tool (EFT), making rigorous C4 data analysis accessible to a broader audience. Outputs include those defining C4 photochemical and biochemical efficiency, the rate of photorespiration, bundle sheath conductance to CO2 diffusion and the in vivo biochemical constants for PEP carboxylase. The EFT compares several methodological variants proposed by different investigators, allowing users to choose the level of complexity required to interpret data. We provide a complete analysis of <span class="hlt">gas</span> <span class="hlt">exchange</span> data on maize (as a model C4 organism and key global crop) to illustrate the approaches, their analysis and interpretation. © 2015 John Wiley & Sons Ltd. © 2016 John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1211010-experimental-investigation-reticulated-porous-alumina-heat-exchanger-high-temperature-gas-heat-recovery','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1211010-experimental-investigation-reticulated-porous-alumina-heat-exchanger-high-temperature-gas-heat-recovery"><span>Experimental investigation of a reticulated porous alumina heat <span class="hlt">exchanger</span> for high temperature <span class="hlt">gas</span> heat recovery</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Banerjee, A; Chandran, RB; Davidson, JH</p> <p>2015-01-22</p> <p>The present study presents an experimental study of a prototype counter-flow heat <span class="hlt">exchanger</span> designed to recover sensible heat from inert and reactive gases flowing through a high temperature solar reactor for splitting CO2. The tube-in-tube heat <span class="hlt">exchanger</span> is comprised of two concentric alumina tubes, each filled with reticulated porous alumina with a nominal porosity of 80% and pore density of 5 pores per inch (ppi). The RPC provides high heat transfer surface area per unit volume (917 m(-1)) with low pressure drop. Measurements include the permeability, inertial coefficient, overall heat transfer coefficient, effectiveness and pressure drop. For laminar flow andmore » an inlet <span class="hlt">gas</span> temperature of 1240 K, the overall heat transfer coefficients are 36-41 W m(-2) K-1. The measured performance is in good agreement with a prior CFD model of the heat <span class="hlt">exchanger</span>. (C) 2014 Elsevier Ltd. All rights reserved.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985agar.symp.....B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985agar.symp.....B"><span>Ceramic heat <span class="hlt">exchangers</span> for <span class="hlt">gas</span> turbines or turbojets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Boudigues, S.; Fabri, J.</p> <p></p> <p>The required performance goals and several proposed designs for SiC heat <span class="hlt">exchangers</span> for aerospace turbines are presented. Ceramic materials are explored as a means for achieving higher operating temperatures while controlling the weight and cost of the heat <span class="hlt">exchangers</span>. Thermodynamic analyses and model tests by ONERA have demonstrated the efficacy of introducing a recooling cycle and placing the heat <span class="hlt">exchangers</span> between stages of the turbine. Sample applications are discussed for small general aviation aircraft and subsonic missiles equipped with single-flux <span class="hlt">exchangers</span>. A double-flux <span class="hlt">exchanger</span> is considered for an aircraft capable of Mach 0.8 speed and at least 11 km altitude for cruise. Finally, the results of initial attempts to manufacture SiC honeycomb heat <span class="hlt">exchangers</span> are detailed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GBioC..31.1579S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GBioC..31.1579S"><span>Oceanic Uptake of Oxygen During Deep Convection Events Through Diffusive and Bubble-Mediated <span class="hlt">Gas</span> <span class="hlt">Exchange</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sun, Daoxun; Ito, Takamitsu; Bracco, Annalisa</p> <p>2017-10-01</p> <p>The concentration of dissolved oxygen (O2) plays fundamental roles in diverse chemical and biological processes throughout the oceans. The balance between the physical supply and the biological consumption controls the O2 level of the interior ocean, and the O2 supply to the deep waters can only occur through deep convection in the polar oceans. We develop a theoretical framework describing the oceanic O2 uptake during open-ocean deep convection events and test it against a suite of numerical sensitivity experiments. Our framework allows for two predictions, confirmed by the numerical simulations. First, both the duration and the intensity of the wintertime cooling contribute to the total O2 uptake for a given buoyancy loss. Stronger cooling leads to deeper convection and the oxygenation can reach down to deeper depths. Longer duration of the cooling period increases the total amount of O2 uptake over the convective season. Second, the bubble-mediated influx of O2 tends to weaken the diffusive influx by shifting the air-sea disequilibrium of O2 toward supersaturation. The degree of compensation between the diffusive and bubble-mediated <span class="hlt">gas</span> <span class="hlt">exchange</span> depends on the dimensionless number measuring the relative strength of oceanic vertical mixing and the <span class="hlt">gas</span> transfer velocity. Strong convective mixing, which may occur under strong cooling, reduces the degree of compensation so that the two components of <span class="hlt">gas</span> <span class="hlt">exchange</span> together drive exceptionally strong oceanic O2 uptake.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940007997','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940007997"><span>Factors controlling sulfur <span class="hlt">gas</span> <span class="hlt">exchange</span> in Sphagnum-dominated wetlands</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Demello, William Zamboni; Hines, Mark E.; Bayley, Suzanne E.</p> <p>1992-01-01</p> <p>Atmosphere-peatland <span class="hlt">exchange</span> of reduced sulfur gases was determined seasonally in fen in NH, and in an artificially-acidified fen at the Experimental Lakes Area (ELA) in Canada. Dimethyl sulfide (DMS) dominated <span class="hlt">gas</span> fluxes at rates as high as 400 nmol/m(sup -2)hr(sup -1). DMS fluxes measured using enclosures were much higher than those calculated using a stagnant-film model, suggesting that Sphagnum regulated efflux. Temperature controlled diel and seasonal variability in DMS emissions. Use of differing enclosure techniques indicated that vegetated peatlands consume atmospheric carbonyl sulfide. Sulfate amendments caused DMS and methane thiol concentrations in near-surface pore waters to increase rapidly, but fluxes of these gases to the atmosphere were not affected. However, emission data from sites experiencing large differences in rates of sulfate deposition from the atmosphere suggested that chronic elevated sulfate inputs enhance DMS emissions from northern wetlands.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23320654','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23320654"><span>Reduction of molecular <span class="hlt">gas</span> diffusion through gaskets in leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> cuvettes by leaf-mediated pores.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Boesgaard, Kristine S; Mikkelsen, Teis N; Ro-Poulsen, Helge; Ibrom, Andreas</p> <p>2013-07-01</p> <p>There is an ongoing debate on how to correct leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> measurements for the unavoidable diffusion leakage that occurs when measurements are done in non-ambient CO2 concentrations. In this study, we present a theory on how the CO2 diffusion gradient over the gasket is affected by leaf-mediated pores (LMP) and how LMP reduce diffusive <span class="hlt">exchange</span> across the gaskets. Recent discussions have so far neglected the processes in the quasi-laminar boundary layer around the gasket. Counter intuitively, LMP reduce the leakage through gaskets, which can be explained by assuming that the boundary layer at the exterior of the cuvette is enriched with air from the inside of the cuvette. The effect can thus be reduced by reducing the boundary layer thickness. The theory clarifies conflicting results from earlier studies. We developed leaf adaptor frames that eliminate LMP during measurements on delicate plant material such as grass leaves with circular cross section, and the effectiveness is shown with respiration measurements on a harp of Deschampsia flexuosa leaves. We conclude that the best solution for measurements with portable photosynthesis systems is to avoid LMP rather than trying to correct for the effects. © 2013 John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28833173','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28833173"><span>Disruption of stomatal lineage signaling or transcriptional regulators has differential effects on mesophyll development, but maintains coordination of <span class="hlt">gas</span> <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dow, Graham J; Berry, Joseph A; Bergmann, Dominique C</p> <p>2017-10-01</p> <p>Stomata are simultaneously tasked with permitting the uptake of carbon dioxide for photosynthesis while limiting water loss from the plant. This process is mainly regulated by guard cell control of the stomatal aperture, but recent advancements have highlighted the importance of several genes that control stomatal development. Using targeted genetic manipulations of the stomatal lineage and a combination of <span class="hlt">gas</span> <span class="hlt">exchange</span> and microscopy techniques, we show that changes in stomatal development of the epidermal layer lead to coupled changes in the underlying mesophyll tissues. This coordinated response tends to match leaf photosynthetic potential (V cmax ) with <span class="hlt">gas-exchange</span> capacity (g smax ), and hence the uptake of carbon dioxide for water lost. We found that different genetic regulators systematically altered tissue coordination in separate ways: the transcription factor SPEECHLESS (SPCH) primarily affected leaf size and thickness, whereas peptides in the EPIDERMAL PATTERNING FACTOR (EPF) family altered cell density in the mesophyll. It was also determined that interlayer coordination required the cell-surface receptor TOO MANY MOUTHS (TMM). These results demonstrate that stomata-specific regulators can alter mesophyll properties, which provides insight into how molecular pathways can organize leaf tissues to coordinate <span class="hlt">gas</span> <span class="hlt">exchange</span> and suggests new strategies for improving plant water-use efficiency. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25887446','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25887446"><span>Submaximal Exercise Pulmonary <span class="hlt">Gas</span> <span class="hlt">Exchange</span> in Left Heart Disease Patients With Different Forms of Pulmonary Hypertension.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Taylor, Bryan J; Smetana, Michael R; Frantz, Robert P; Johnson, Bruce D</p> <p>2015-08-01</p> <p>We determined whether pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> indices during submaximal exercise are different in heart failure (HF) patients with combined post- and pre-capillary pulmonary hypertension (PPC-PH) versus HF patients with isolated post-capillary PH (IPC-PH) or no PH. Pulmonary hemodynamics and pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> were assessed during rest and submaximal exercise in 39 HF patients undergoing right heart catheterization. After hemodynamic evaluation, patients were classified as having no PH (n = 11), IPC-PH (n = 12), or PPC-PH (n = 16). At an equivalent oxygen consumption, end-tidal CO2 (PETCO2) and arterial oxygen saturation (SaO2) were greater in no-PH and IPC-PH versus PPC-PH patients (36.1 ± 3.2 vs. 31.7 ± 4.5 vs. 26.2 ± 4.7 mm Hg and 97 ± 2 vs. 96 ± 3 vs. 91 ± 1%, respectively). Conversely, dead-space ventilation (VD/VT) and the ventilatory equivalent for carbon dioxide (V˙(E)/V˙CO2 ratio) were lower in no-PH and IPC-PH versus PPC-PH patients (0.37 ± 0.05 vs. 0.38 ± 0.04 vs. 0.47 ± 0.03 and 38 ± 5 vs. 42 ± 8 vs. 51 ± 8, respectively). The exercise-induced change in V(D)/V(T), V˙(E)/V˙CO2 ratio, and PETCO2 correlated significantly with the change in mean pulmonary arterial pressure, diastolic pressure difference, and transpulmonary pressure gradient in PPC-PH patients only. Noninvasive pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> indices during submaximal exercise are different in HF patients with combined post- and pre-capillary PH compared with patients with isolated post-capillary PH or no PH. Copyright © 2015 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6148686','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/6148686"><span>Flue <span class="hlt">gas</span> desulfurization</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Im, K.H.; Ahluwalia, R.K.</p> <p>1984-05-01</p> <p>The invention involves a combustion process in which combustion <span class="hlt">gas</span> containing sulfur oxide is directed past a series of heat <span class="hlt">exchangers</span> to a stack and in which a sodium compound is added to the combustion <span class="hlt">gas</span> in a temparature zone of above about 1400 K to form Na/sub 2/SO/sub 4/. Preferably, the temperature is above about 1800 K and the sodium compound is present as a vapor to provide a <span class="hlt">gas-gas</span> reaction to form Na/sub 2/SO/sub 4/ as a liquid. Since liquid Na/sub 2/SO/sub 4/ may cause fouling of heat <span class="hlt">exchanger</span> surfaces downstream from the combustion zone, the process advantageously includes the step of injecting a cooling <span class="hlt">gas</span> downstream of the injection of the sodium compound yet upstream of one or more heat <span class="hlt">exchangers</span> to cool the combustion <span class="hlt">gas</span> to below about 1150 K and form solid Na/sub 2/SO/sub 4/. The cooling <span class="hlt">gas</span> is preferably a portion of the combustion <span class="hlt">gas</span> downstream which may be recycled for cooling. It is further advantageous to utilize an electrostatic precipitator downstream of the heat <span class="hlt">exchangers</span> to recover the Na/sub 2/SO/sub 4/. It is also advantageous in the process to remove a portion of the combustion <span class="hlt">gas</span> cleaned in the electrostatic precipitator and recycle that portion upstream to use as the cooling <span class="hlt">gas</span>. 3 figures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960050285','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960050285"><span>Design of Plant <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Experiments in a Variable Pressure Growth Chamber</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Corey, Kenneth A.</p> <p>1996-01-01</p> <p>Sustainable human presence in extreme environments such as lunar and martian bases will require bioregenerative components to human life support systems where plants are used for generation of oxygen, food, and water. Reduced atmospheric pressures will be used to minimize mass and engineering requirements. Few studies have assessed the metabolic and developmental responses of plants to reduced pressure and varied oxygen atmospheres. The first tests of hypobaric pressures on plant <span class="hlt">gas</span> <span class="hlt">exchange</span> and biomass production at the Johnson Space Center will be initiated in January 1996 in the Variable Pressure Growth Chamber (VPGC), a large, closed plant growth chamber rated for 10.2 psi. Experiments were designed and protocols detailed for two complete growouts each of lettuce and wheat to generate a general database for human life support requirements and to answer questions about plant growth processes in reduced pressure and varied oxygen environments. The central objective of crop growth studies in the VPGC is to determine the influence of reduced pressure and reduced oxygen on the rates of photosynthesis, dark respiration, evapotranspiration and biomass production of lettuce and wheat. Due to the constraint of one experimental unit, internal controls, called pressure transients, will be used to evaluate rates of CO2 uptake, O2 evolution, and H2O generation. Pressure transients will give interpretive power to the results of repeated growouts at both reduced and ambient pressures. Other experiments involve the generation of response functions to partial pressures of O2 and CO2 and to light intensity. Protocol for determining and calculating rates of <span class="hlt">gas</span> <span class="hlt">exchange</span> have been detailed. In order to build these databases and implement the necessary treatment combinations in short time periods, specific requirements for <span class="hlt">gas</span> injections and removals have been defined. A set of system capability checks will include determination of leakage rates conducted prior to the actual crop</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/14095','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/14095"><span>Effects of moisture and nitrogen stress on <span class="hlt">gas</span> <span class="hlt">exchange</span> and nutrient resorption in Quercus rubra seedlings</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>K. Francis Salifu; Douglass F. Jacobs</p> <p>2008-01-01</p> <p>The effects of simulated soil fertility at three levels (poor, medium, and rich soils) and moisture stress at two levels (well watered versus moisture stressed) on <span class="hlt">gas</span> <span class="hlt">exchange</span> and foliar nutrient resorption in 1+0 bareroot northern red oak (Quercus rubra) seedlings were evaluated. Current nitrogen (N) uptake was labeled with the stable isotope</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title10-vol4/pdf/CFR-2011-title10-vol4-sec590-209.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title10-vol4/pdf/CFR-2011-title10-vol4-sec590-209.pdf"><span>10 CFR 590.209 - <span class="hlt">Exchanges</span> by displacement.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-01-01</p> <p>... 10 Energy 4 2011-01-01 2011-01-01 false <span class="hlt">Exchanges</span> by displacement. 590.209 Section 590.209 Energy... Natural <span class="hlt">Gas</span> § 590.209 <span class="hlt">Exchanges</span> by displacement. Any importer of natural <span class="hlt">gas</span> may enter into an <span class="hlt">exchange</span> by displacement agreement without the prior authorization of the Assistant Secretary when the net effect of the...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title10-vol4/pdf/CFR-2010-title10-vol4-sec590-209.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title10-vol4/pdf/CFR-2010-title10-vol4-sec590-209.pdf"><span>10 CFR 590.209 - <span class="hlt">Exchanges</span> by displacement.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 10 Energy 4 2010-01-01 2010-01-01 false <span class="hlt">Exchanges</span> by displacement. 590.209 Section 590.209 Energy... Natural <span class="hlt">Gas</span> § 590.209 <span class="hlt">Exchanges</span> by displacement. Any importer of natural <span class="hlt">gas</span> may enter into an <span class="hlt">exchange</span> by displacement agreement without the prior authorization of the Assistant Secretary when the net effect of the...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title10-vol4/pdf/CFR-2014-title10-vol4-sec590-209.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title10-vol4/pdf/CFR-2014-title10-vol4-sec590-209.pdf"><span>10 CFR 590.209 - <span class="hlt">Exchanges</span> by displacement.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-01-01</p> <p>... 10 Energy 4 2014-01-01 2014-01-01 false <span class="hlt">Exchanges</span> by displacement. 590.209 Section 590.209 Energy... Natural <span class="hlt">Gas</span> § 590.209 <span class="hlt">Exchanges</span> by displacement. Any importer of natural <span class="hlt">gas</span> may enter into an <span class="hlt">exchange</span> by displacement agreement without the prior authorization of the Assistant Secretary when the net effect of the...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title10-vol4/pdf/CFR-2012-title10-vol4-sec590-209.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title10-vol4/pdf/CFR-2012-title10-vol4-sec590-209.pdf"><span>10 CFR 590.209 - <span class="hlt">Exchanges</span> by displacement.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-01-01</p> <p>... 10 Energy 4 2012-01-01 2012-01-01 false <span class="hlt">Exchanges</span> by displacement. 590.209 Section 590.209 Energy... Natural <span class="hlt">Gas</span> § 590.209 <span class="hlt">Exchanges</span> by displacement. Any importer of natural <span class="hlt">gas</span> may enter into an <span class="hlt">exchange</span> by displacement agreement without the prior authorization of the Assistant Secretary when the net effect of the...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title10-vol4/pdf/CFR-2013-title10-vol4-sec590-209.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title10-vol4/pdf/CFR-2013-title10-vol4-sec590-209.pdf"><span>10 CFR 590.209 - <span class="hlt">Exchanges</span> by displacement.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-01-01</p> <p>... 10 Energy 4 2013-01-01 2013-01-01 false <span class="hlt">Exchanges</span> by displacement. 590.209 Section 590.209 Energy... Natural <span class="hlt">Gas</span> § 590.209 <span class="hlt">Exchanges</span> by displacement. Any importer of natural <span class="hlt">gas</span> may enter into an <span class="hlt">exchange</span> by displacement agreement without the prior authorization of the Assistant Secretary when the net effect of the...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040112678&hterms=ketamine&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dketamine','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040112678&hterms=ketamine&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dketamine"><span>Vasomotor tone does not affect perfusion heterogeneity and <span class="hlt">gas</span> <span class="hlt">exchange</span> in normal primate lungs during normoxia</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Glenny, R. W.; Robertson, H. T.; Hlastala, M. P.</p> <p>2000-01-01</p> <p>To determine whether vasoregulation is an important cause of pulmonary perfusion heterogeneity, we measured regional blood flow and <span class="hlt">gas</span> <span class="hlt">exchange</span> before and after giving prostacyclin (PGI(2)) to baboons. Four animals were anesthetized with ketamine and mechanically ventilated. Fluorescent microspheres were used to mark regional perfusion before and after PGI(2) infusion. The lungs were subsequently excised, dried inflated, and diced into approximately 2-cm(3) pieces (n = 1,208-1,629 per animal) with the spatial coordinates recorded for each piece. Blood flow to each piece was determined for each condition from the fluorescent signals. Blood flow heterogeneity did not change with PGI(2) infusion. Two other measures of spatial blood flow distribution, the fractal dimension and the spatial correlation, did not change with PGI(2) infusion. Alveolar-arterial O(2) differences did not change with PGI(2) infusion. We conclude that, in normal primate lungs during normoxia, vasomotor tone is not a significant cause of perfusion heterogeneity. Despite the heterogeneous distribution of blood flow, active regulation of regional perfusion is not required for efficient <span class="hlt">gas</span> <span class="hlt">exchange</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26670813','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26670813"><span>Ventilation and <span class="hlt">gas</span> <span class="hlt">exchange</span> management after cardiac arrest.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sutherasan, Yuda; Raimondo, Pasquale; Pelosi, Paolo</p> <p>2015-12-01</p> <p>For several decades, physicians had integrated several interventions aiming to improve the outcomes in post-cardiac arrest patients. However, the mortality rate after cardiac arrest is still as high as 50%. Post-cardiac arrest syndrome is associated with high morbidity and mortality due to not only poor neurological outcome and cardiovascular failure but also respiratory dysfunction. To minimize ventilator-associated lung injury, protective mechanical ventilation by using low tidal volume ventilation and driving pressure may decrease pulmonary complications and improve survival. Low level of positive end-expiratory pressure (PEEP) can be initiated and titrated with careful cardiac output and respiratory mechanics monitoring. Furthermore, optimizing <span class="hlt">gas</span> <span class="hlt">exchange</span> by avoiding hypoxia and hyperoxia as well as maintaining normocarbia may improve neurological and survival outcome. Early multidisciplinary cardiac rehabilitation intervention is recommended. Minimally invasive monitoring techniques, that is, echocardiography, transpulmonary thermodilution method measuring extravascular lung water, as well as transcranial Doppler ultrasound, might be useful to improve appropriate management of post-cardiac arrest patients. Copyright © 2015 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=treatment+AND+gas&id=EJ1096645','ERIC'); return false;" href="https://eric.ed.gov/?q=treatment+AND+gas&id=EJ1096645"><span>Impaired <span class="hlt">Gas</span> <span class="hlt">Exchange</span> at Birth and Risk of Intellectual Disability and Autism: A Meta-Analysis</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Modabbernia, Amirhossein; Mollon, Josephine; Boffetta, Paolo; Reichenberg, Abraham</p> <p>2016-01-01</p> <p>We conducted meta-analyses of 67 studies on the association between neonatal proxies of impaired <span class="hlt">gas</span> <span class="hlt">exchange</span> and intellectual disability (ID) or autism spectrum disorders (ASD). Neonatal acidosis was associated with an odds ratio (OR) of 3.55 [95% confidence interval (95% CI) 2.23-5.49] for ID and an OR of 1.10 (95% CI 0.91-1.31) for ASD.…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1738K0008N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1738K0008N"><span>The predictive protective control of the heat <span class="hlt">exchanger</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nevriva, Pavel; Filipova, Blanka; Vilimec, Ladislav</p> <p>2016-06-01</p> <p>The paper deals with the predictive control applied to flexible cogeneration energy system FES. FES was designed and developed by the VITKOVICE POWER ENGINEERING joint-stock company and represents a new solution of decentralized cogeneration energy sources. In FES, the heating medium is flue <span class="hlt">gas</span> generated by combustion of a solid fuel. The heated medium is power <span class="hlt">gas</span>, which is a <span class="hlt">gas</span> mixture of air and water steam. Power <span class="hlt">gas</span> is superheated in the main heat <span class="hlt">exchanger</span> and led to <span class="hlt">gas</span> turbines. To protect the main heat <span class="hlt">exchanger</span> against damage by overheating, the novel predictive protective control based on the mathematical model of <span class="hlt">exchanger</span> was developed. The paper describes the principle, the design and the simulation of the predictive protective method applied to main heat <span class="hlt">exchanger</span> of FES.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19203951','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19203951"><span>Coordination of leaf structure and <span class="hlt">gas</span> <span class="hlt">exchange</span> along a height gradient in a tall conifer.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Woodruff, D R; Meinzer, F C; Lachenbruch, B; Johnson, D M</p> <p>2009-02-01</p> <p>The gravitational component of water potential and frictional resistance during transpiration lead to substantial reductions in leaf water potential (Psi(l)) near the tops of tall trees, which can influence both leaf growth and physiology. We examined the relationships between morphological features and <span class="hlt">gas</span> <span class="hlt">exchange</span> in foliage collected near the tops of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees of different height classes ranging from 5 to 55 m. This sampling allowed us to investigate the effects of tree height on leaf structural characteristics in the absence of potentially confounding factors such as irradiance, temperature, relative humidity and branch length. The use of cut foliage for measurement of intrinsic <span class="hlt">gas-exchange</span> characteristics allowed identification of height-related trends without the immediate influences of path length and gravity. Stomatal density, needle length, needle width and needle area declined with increasing tree height by 0.70 mm(-2) m(-1), 0.20 mm m(-1), 5.9 x 10(-3) mm m(-1) and 0.012 mm(2) m(-1), respectively. Needle thickness and mesophyll thickness increased with tree height by 4.8 x 10(-2) mm m(-1) and 0.74 microm m(-1), respectively. Mesophyll conductance (g(m)) and CO(2) assimilation in ambient [CO(2)] (A(amb)) decreased by 1.1 mmol m(-2) s(-1) per m and 0.082 micromol m(-2) s(-1) per m increase in height, respectively. Mean reductions in g(m) and A(amb) of foliage from 5 to 55 m were 47% and 42%, respectively. The observed trend in A(amb) was associated with g(m) and several leaf anatomic characteristics that are likely to be determined by the prevailing vertical tension gradient during foliar development. A linear increase in foliar delta(13)C values with height (0.042 per thousand m(-1)) implied that relative stomatal and mesophyll limitations of photosynthesis in intact shoots increased with height. These data suggest that increasing height leads to both fixed structural constraints on leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990mshe.rept.....D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990mshe.rept.....D"><span>Microtube strip heat <span class="hlt">exchanger</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Doty, F. D.</p> <p>1990-12-01</p> <p>Doty Scientific (DSI) believes their microtube-strip heat <span class="hlt">exchanger</span> will contribute significantly to the following: (1) the closed Brayton cycles being pursued at MIT, NASA, and elsewhere; (2) reverse Brayton cycle cryocoolers, currently being investigated by NASA for space missions, being applied to MRI superconducting magnets; and (3) high-efficiency cryogenic <span class="hlt">gas</span> separation schemes for CO2 removal from exhaust stacks. The goal of this current study is to show the potential for substantial progress in high-effectiveness, low-cost, <span class="hlt">gas-to-gas</span> heat <span class="hlt">exchangers</span> for diverse applications at temperatures from below 100 K to above 1000 K. To date, the highest effectiveness measured is about 98 percent and relative pressure drops below 0.1 percent with a specific conductance of about 45 W/kgK are reported. During the pre-award period DSI built and tested a 3-module heat <span class="hlt">exchanger</span> bank using 103-tube microtube strip (MTS) modules. To add to their analytical capabilities, DSI has acquired computational fluid dynamics (CFD) software. This report describes the pre-award work and the status of the ten tasks of the current project, which are: analyze flow distribution and thermal stresses within individual modules; design a heat <span class="hlt">exchanger</span> bank of ten modules with 400 microtube per module; obtain production quality tubestrip die and AISI 304 tubestrips; obtain production quality microtubing; construct revised MTS heat <span class="hlt">exchanger</span>; construct dies and fixtures for prototype heat <span class="hlt">exchanger</span>; construct 100 MTS modules; assemble 8 to 10 prototype MTS heat <span class="hlt">exchangers</span>; test prototype MTS heat <span class="hlt">exchanger</span>; and verify test through independent means.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/53171','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/53171"><span>A dynamic leaf <span class="hlt">gas-exchange</span> strategy is conserved in woody plants under changing ambient CO2 : evidence from carbon isotope discrimination in paleo and CO2 enrichment studies</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Steven L. Voelker; J. Renee Brooks; Frederick C. Meinzer; Rebecca Anderson; Martin K.-F. Bader; Giovanna Battipaglia; Katie M. Becklin; David Beerling; Didier Bert; Julio L. Betancourt; Todd E. Dawson; Jean-Christophe Domec; Richard P. Guyette; Christian K??rner; Steven W. Leavitt; Sune Linder; John D. Marshall; Manuel Mildner; Jerome Ogee; Irina Panyushkina; Heather J. Plumpton; Kurt S. Pregitzer; Matthias Saurer; Andrew R. Smith; Rolf T. W. Siegwolf; Michael C. Stambaugh; Alan F. Talhelm; Jacques C. Tardif; Peter K. Van de Water; Joy K. Ward; Lisa Wingate</p> <p>2016-01-01</p> <p>Rising atmospheric [CO2], ca, is expected to affect stomatal regulation of leaf <span class="hlt">gas-exchange</span> of woody plants, thus influencing energy fluxes as well as carbon (C), water, and nutrient cycling of forests. Researchers have proposed various strategies for stomatal regulation of leaf <span class="hlt">gas-exchange</span> that include maintaining a constant leaf internal [CO...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1711423W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1711423W"><span>Sensitivity of simulated deep ocean natural radiocarbon to <span class="hlt">gas</span> <span class="hlt">exchange</span> velocity and historical atmospheric Δ14C variations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wagner, Hannes; Koeve, Wolfgang; Kriest, Iris; Oschlies, Andreas</p> <p>2015-04-01</p> <p>Simulated deep ocean natural radiocarbon is frequently used to assess model performance of deep ocean ventilation in Ocean General Circulation Models (OGCMs). It has been shown to be sensitive to a variety of model parameters, such as the mixing parameterization, convection scheme and vertical resolution. Here we use three different ocean models (MIT2.8, ECCO, UVic) to evaluate the sensitivity of simulated deep ocean natural radiocarbon to two other factors, while keeping the model physics constant: (1) the <span class="hlt">gas</span> <span class="hlt">exchange</span> velocity and (2) historic variations in atmospheric Δ^1^4C boundary conditions. We find that simulated natural Δ^1^4C decreases by 14-20 ‰ throughout the deep ocean and consistently in all three models, if the <span class="hlt">gas</span> <span class="hlt">exchange</span> velocity is lowered by 30 % with respect to the OCMIP-2 protocol, to become more consistent with newer estimates of the oceans uptake of bomb derived ^1^4C. Simulated deep ocean natural Δ^1^4C furthermore decreases by 3-9 ‰ throughout the deep Pacific, Indian and Southern Oceans and consistently in all three models, if the models are forced with the observed atmospheric Δ^1^4C history, instead of an often made pragmatic assumption of a constant atmospheric Δ^1^4C value of zero. Applying both improvements (<span class="hlt">gas</span> <span class="hlt">exchange</span> reduction, as well as atmospheric Δ^1^4C history implementation) concomitantly and accounting for the present uncertainty in <span class="hlt">gas</span> <span class="hlt">exchange</span> velocity estimates (between 10 and 40 % reduction with respect to the OCMIP-2 protocol) simulated deep ocean Δ^1^4C decreases by 10-30 ‰ throughout the deep Pacific, Indian and Southern Ocean. This translates to a ^1^4C-age increase of 100-300 years and indicates, that models, which in former assessments (based on the OCMIP-2 protocol) had been identified to have an accurate deep ocean ventilation, should now be regarded as rather having a bit too sluggish a ventilation. Models, which on the other hand had been identified to have a bit too fast a deep ocean ventilation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1393514','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1393514"><span>Optimized heat <span class="hlt">exchange</span> in a CO2 de-sublimation process</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Baxter, Larry; Terrien, Paul; Tessier, Pascal</p> <p></p> <p>The present invention is a process for removing carbon dioxide from a compressed <span class="hlt">gas</span> stream including cooling the compressed <span class="hlt">gas</span> in a first heat <span class="hlt">exchanger</span>, introducing the cooled <span class="hlt">gas</span> into a de-sublimating heat <span class="hlt">exchanger</span>, thereby producing a first solid carbon dioxide stream and a first carbon dioxide poor <span class="hlt">gas</span> stream, expanding the carbon dioxide poor <span class="hlt">gas</span> stream, thereby producing a second solid carbon dioxide stream and a second carbon dioxide poor <span class="hlt">gas</span> stream, combining the first solid carbon dioxide stream and the second solid carbon dioxide stream, thereby producing a combined solid carbon dioxide stream, and indirectly <span class="hlt">exchanging</span> heat betweenmore » the combined solid carbon dioxide stream and the compressed <span class="hlt">gas</span> in the first heat <span class="hlt">exchanger</span>.« less</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24874437','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24874437"><span>Dissolution without disappearing: multicomponent <span class="hlt">gas</span> <span class="hlt">exchange</span> for CO2 bubbles in a microfluidic channel.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shim, Suin; Wan, Jiandi; Hilgenfeldt, Sascha; Panchal, Prathamesh D; Stone, Howard A</p> <p>2014-07-21</p> <p>We studied the dissolution dynamics of CO2 <span class="hlt">gas</span> bubbles in a microfluidic channel, both experimentally and theoretically. In the experiments, spherical CO2 bubbles in a flow of a solution of sodium dodecyl sulfate (SDS) first shrink rapidly before attaining an equilibrium size. In the rapid dissolution regime, the time to obtain a new equilibrium is 30 ms regardless of SDS concentration, and the equilibrium radius achieved varies with the SDS concentration. To explain the lack of complete dissolution, we interpret the results by considering the effects of other gases (O2, N2) that are already dissolved in the aqueous phase, and we develop a multicomponent dissolution model that includes the effect of surface tension and the liquid pressure drop along the channel. Solutions of the model for a stationary <span class="hlt">gas</span> bubble show good agreement with the experimental results, which lead to our conclusion that the equilibrium regime is obtained by <span class="hlt">gas</span> <span class="hlt">exchange</span> between the bubbles and liquid phase. Also, our observations from experiments and model calculations suggest that SDS molecules on the <span class="hlt">gas</span>-liquid interface form a diffusion barrier, which controls the dissolution behaviour and the eventual equilibrium radius of the bubble.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1614801O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1614801O"><span>Stomata size and spatial pattern effects on leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> - a quantitative assessment of plant evolutionary choices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Or, Dani; Assouline, Shmuel; Aminzadeh, Milad; Haghighi, Erfan; Schymanski, Stan; Lehmann, Peter</p> <p>2014-05-01</p> <p>Land plants developed a dynamically <span class="hlt">gas</span>-permeable layer at their leaf surfaces to allow CO2 uptake for photosynthesis while controlling water vapor loss through numerous adjustable openings (stomata) in the impervious leaf epidermis. Details of stomata structure, density and function may vary greatly among different plant families and respond to local environmental conditions, yet they share basic traits in dynamically controlling gaseous <span class="hlt">exchange</span> rates by varying stomata apertures. We implement a pore scale <span class="hlt">gas</span> diffusion model to quantitatively interpret the functionality of different combinations of stomata size and pattern on leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and thermal management based on data from fossil records and contemporary data sets. Considering all available data we draw several general conclusions concerning stomata design considerations: (1) the sizes and densities of stomata in the available fossil record leaves were designed to evaporate at rates in the range 0.75≤e/e0 ≤0.99 (relative to free water evaporation); (2) examination of evaporation curves show that for a given stomata size, the density (jointly defining the leaf evaporating area when fully open) was chosen to enable a high sensitivity in reducing evaporation rate with incremental stomatal closure, nevertheless, results show the design includes safety margins to account for different wind conditions (boundary layer thickness); (3) scaled for mean vapor flux, the size of stomata plays a minor role in the uniformity of leaf thermal field for a given stomata density. These principles enable rationale assessment of plant response to raising CO2, and provide a physical framework for considering the consequences of different stomata patterns (patchy) on leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> (and thermal regime). In contrast with present quantitative description of traits and functionality of these dynamic covers in terms of gaseous diffusion resistance (or conductance), where stomata size, density and spatial pattern are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6999942-gas-exchange-intrapulmonary-distribution-ventilation-during-continuous-flow-ventilation','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6999942-gas-exchange-intrapulmonary-distribution-ventilation-during-continuous-flow-ventilation"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span> and intrapulmonary distribution of ventilation during continuous-flow ventilation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Vettermann, J.; Brusasco, V.; Rehder, K.</p> <p>1988-05-01</p> <p>In 12 anesthetized paralyzed dogs, pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> and intrapulmonary inspired <span class="hlt">gas</span> distribution were compared between continuous-flow ventilation (CFV) and conventional mechanical ventilation (CMV). Nine dogs were studied while they were lying supine, and three dogs were studied while they were lying prone. A single-lumen catheter for tracheal insufflation and a double-lumen catheter for bilateral endobronchial insufflation (inspired O2 fraction = 0.4; inspired minute ventilation = 1.7 +/- 0.3 (SD) 1.kg-1.min-1) were evaluated. Intrapulmonary <span class="hlt">gas</span> distribution was assessed from regional 133Xe clearances. In dogs lying supine, CO2 elimination was more efficient with endobronchial insufflation than with tracheal insufflation, but themore » alveolar-arterial O2 partial pressure difference was larger during CFV than during CMV, regardless of the type of insufflation. By contrast, endobronchial insufflation maintained both arterial PCO2 and alveolar-arterial O2 partial pressure difference at significantly lower levels in dogs lying prone than in dogs lying supine. In dogs lying supine, the dependent lung was preferentially ventilated during CMV but not during CFV. In dogs lying prone, <span class="hlt">gas</span> distribution was uniform with both modes of ventilation. The alveolar-arterial O2 partial pressure difference during CFV in dogs lying supine was negatively correlated with the reduced ventilation of the dependent lung, which suggests that increased ventilation-perfusion mismatching was responsible for the increase in alveolar-arterial O2 partial pressure difference. The more efficient oxygenation during CFV in dogs lying prone suggests a more efficient matching of ventilation to perfusion, presumably because the distribution of blood flow is also nearly uniform.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26188268','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26188268"><span>Hypoxia and hypercarbia in endophagous insects: Larval position in the plant <span class="hlt">gas</span> <span class="hlt">exchange</span> network is key.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pincebourde, Sylvain; Casas, Jérôme</p> <p>2016-01-01</p> <p><span class="hlt">Gas</span> composition is an important component of any micro-environment. Insects, as the vast majority of living organisms, depend on O2 and CO2 concentrations in the air they breathe. Low O2 (hypoxia), and high CO2 (hypercarbia) levels can have a dramatic effect. For phytophagous insects that live within plant tissues (endophagous lifestyle), <span class="hlt">gas</span> is <span class="hlt">exchanged</span> between ambient air and the atmosphere within the insect habitat. The insect larva contributes to the modification of this environment by expiring CO2. Yet, knowledge on the <span class="hlt">gas</span> <span class="hlt">exchange</span> network in endophagous insects remains sparse. Our study identified mechanisms that modulate <span class="hlt">gas</span> composition in the habitat of endophagous insects. Our aim was to show that the mere position of the insect larva within plant tissues could be used as a proxy for estimating risk of occurrence of hypoxia and hypercarbia, despite the widely diverse life history traits of these organisms. We developed a conceptual framework for a <span class="hlt">gas</span> diffusion network determining <span class="hlt">gas</span> composition in endophagous insect habitats. We applied this framework to mines, galls and insect tunnels (borers) by integrating the numerous obstacles along O2 and CO2 pathways. The nature and the direction of <span class="hlt">gas</span> transfers depended on the physical structure of the insect habitat, the photosynthesis activity as well as stomatal behavior in plant tissues. We identified the insect larva position within the <span class="hlt">gas</span> diffusion network as a predictor of risk exposure to hypoxia and hypercarbia. We ranked endophagous insect habitats in terms of risk of exposure to hypoxia and/or hypercarbia, from the more to the less risky as cambium mines>borer tunnels≫galls>bark mines>mines in aquatic plants>upper and lower surface mines. Furthermore, we showed that the photosynthetically active tissues likely assimilate larval CO2 produced. In addition, temperature of the microhabitat and atmospheric CO2 alter <span class="hlt">gas</span> composition in the insect habitat. We predict that (i) hypoxia indirectly favors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991mshe.reptS....D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991mshe.reptS....D"><span>Microtube strip heat <span class="hlt">exchanger</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Doty, F. D.</p> <p>1991-10-01</p> <p>This progress report is for the September-October 1991 quarter. We have demonstrated feasibility of higher specific conductance by a factor of five than any other work in high-temperature <span class="hlt">gas-to-gas</span> <span class="hlt">exchangers</span>. These laminar-flow, microtube <span class="hlt">exchangers</span> exhibit extremely low pressure drop compared to alternative compact designs under similar conditions because of their much shorter flow length and larger total flow area for lower flow velocities. The design appears to be amenable to mass production techniques, but considerable process development remains. The reduction in materials usage and the improved heat <span class="hlt">exchanger</span> performance promise to be of enormous significance in advanced engine designs and in cryogenics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/903468','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/903468"><span><span class="hlt">Gas</span> Hydrate Storage of Natural <span class="hlt">Gas</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Rudy Rogers; John Etheridge</p> <p>2006-03-31</p> <p>Environmental and economic benefits could accrue from a safe, above-ground, natural-<span class="hlt">gas</span> storage process allowing electric power plants to utilize natural <span class="hlt">gas</span> for peak load demands; numerous other applications of a <span class="hlt">gas</span> storage process exist. A laboratory study conducted in 1999 to determine the feasibility of a <span class="hlt">gas</span>-hydrates storage process looked promising. The subsequent scale-up of the process was designed to preserve important features of the laboratory apparatus: (1) symmetry of hydrate accumulation, (2) favorable surface area to volume ratio, (3) heat <span class="hlt">exchanger</span> surfaces serving as hydrate adsorption surfaces, (4) refrigeration system to remove heat liberated from bulk hydrate formation, (5)more » rapid hydrate formation in a non-stirred system, (6) hydrate self-packing, and (7) heat-<span class="hlt">exchanger</span>/adsorption plates serving dual purposes to add or extract energy for hydrate formation or decomposition. The hydrate formation/storage/decomposition Proof-of-Concept (POC) pressure vessel and supporting equipment were designed, constructed, and tested. This final report details the design of the scaled POC <span class="hlt">gas</span>-hydrate storage process, some comments on its fabrication and installation, checkout of the equipment, procedures for conducting the experimental tests, and the test results. The design, construction, and installation of the equipment were on budget target, as was the tests that were subsequently conducted. The budget proposed was met. The primary goal of storing 5000-scf of natural <span class="hlt">gas</span> in the <span class="hlt">gas</span> hydrates was exceeded in the final test, as 5289-scf of <span class="hlt">gas</span> storage was achieved in 54.33 hours. After this 54.33-hour period, as pressure in the formation vessel declined, additional <span class="hlt">gas</span> went into the hydrates until equilibrium pressure/temperature was reached, so that ultimately more than the 5289-scf storage was achieved. The time required to store the 5000-scf (48.1 hours of operating time) was longer than designed. The lower <span class="hlt">gas</span> hydrate formation rate is attributed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19855338','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19855338"><span>Noninvasive determination of anaerobic threshold by monitoring the %SpO2 changes and respiratory <span class="hlt">gas</span> <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nikooie, Roohollah; Gharakhanlo, Reza; Rajabi, Hamid; Bahraminegad, Morteza; Ghafari, Ali</p> <p>2009-10-01</p> <p>The purpose of this study was to determine the validity of noninvasive anaerobic threshold (AT) estimation using %SpO2 (arterial oxyhemoglobin saturation) changes and respiratory <span class="hlt">gas</span> <span class="hlt">exchanges</span>. Fifteen active, healthy males performed 2 graded exercise tests on a motor-driven treadmill in 2 separated sessions. Respiratory <span class="hlt">gas</span> <span class="hlt">exchanges</span> and heart rate (HR), lactate concentration, and %SpO2 were measured continuously throughout the test. Anaerobic threshold was determined based on blood lactate concentration (lactate-AT), %SpO2 changes (%SpO2-AT), respiratory <span class="hlt">exchange</span> ratio (RER-AT), V-slope method (V-slope-AT), and ventilatory equivalent for O2 (EqO2-AT). Blood lactate measuring was considered as gold standard assessment of AT and was applied to confirm the validity of other noninvasive methods. The mean O2 corresponding to lactate-AT, %SpO2-AT, RER-AT, V-slope -AT, and EqO2-AT were 2176.6 +/- 206.4, 1909.5 +/- 221.4, 2141.2 +/- 245.6, 1933.7 +/- 216.4, and 1975 +/- 232.4, respectively. Intraclass correlation coefficient (ICC) analysis indicates a significant correlation between 4 noninvasive methods and the criterion method. Blond-Altman plots showed the good agreement between O2 corresponding to AT in each method and lactate-AT (95% confidence interval (CI). Our results indicate that a noninvasive and easy procedure of monitoring the %SpO2 is a valid method for estimation of AT. Also, in the present study, the respiratory <span class="hlt">exchange</span> ratio (RER) method seemed to be the best respiratory index for noninvasive estimation of anaerobic threshold, and the heart rate corresponding to AT predicted by this method can be used by coaches and athletes to define training zones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5569668','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5569668"><span>Solvent <span class="hlt">Exchange</span> Leading to Nanobubble Nucleation: A Molecular Dynamics Study</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2017-01-01</p> <p>The solvent <span class="hlt">exchange</span> procedure has become the most-used protocol to produce surface nanobubbles, while the molecular mechanisms behind the solvent <span class="hlt">exchange</span> are far from being fully understood. In this paper, we build a simple model and use molecular dynamics simulations to investigate the dynamic characteristics of solvent <span class="hlt">exchange</span> for producing nanobubbles. We find that at the first stage of solvent <span class="hlt">exchange</span>, there exists an interface between interchanging solvents of different <span class="hlt">gas</span> solubility. This interface moves toward the substrate gradually as the <span class="hlt">exchange</span> process proceeds. Our simulations reveal directed diffusion of <span class="hlt">gas</span> molecules against the <span class="hlt">gas</span> concentration gradient, driven by the solubility gradient of the liquid composition across the moving solvent–solvent interface. It is this directed diffusion that causes <span class="hlt">gas</span> retention and produces a local <span class="hlt">gas</span> oversaturation much higher near the substrate than far from it. At the second stage of solvent <span class="hlt">exchange</span>, the high local <span class="hlt">gas</span> oversaturation leads to bubble nucleation either on the solid surface or in the bulk solution, which is found to depend on the substrate hydrophobicity and the degree of local <span class="hlt">gas</span> oversaturation. Our findings suggest that solvent <span class="hlt">exchange</span> could be developed into a standard procedure to produce oversaturation and used to a variety of nucleation applications other than generating nanobubbles. PMID:28742364</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B13B0614R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B13B0614R"><span>Experimental and Numerical Investigation of Guest Molecule <span class="hlt">Exchange</span> Kinetics based on the 2012 Ignik Sikumi <span class="hlt">Gas</span> Hydrate Field Trial</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruprecht Yonkofski, C. M.; Horner, J.; White, M. D.</p> <p>2015-12-01</p> <p>In 2012 the U.S. DOE/NETL, ConocoPhillips Company, and Japan Oil, <span class="hlt">Gas</span> and Metals National Corporation jointly sponsored the first field trial of injecting a mixture of N2-CO2 into a CH4-hydrate bearing formation beneath the permafrost on the Alaska North Slope. Known as the Ignik Sikumi #1 <span class="hlt">Gas</span> Hydrate Field Trial, this experiment involved three stages: 1) the injection of a N2-CO2 mixture into a targeted hydrate-bearing layer, 2) a 4-day pressurized soaking period, and 3) a sustained depressurization and fluid production period. Data collected during the three stages of the field trial were made available after a thorough quality check. The Ignik Sikumi #1 data set is extensive, but contains no direct evidence of the guest-molecule <span class="hlt">exchange</span> process. This study uses numerical simulation to provide an interpretation of the CH4/CO2/N2 guest molecule <span class="hlt">exchange</span> process that occurred at Ignik Sikumi #1. Simulations were further informed by experimental observations. The goal of the scoping experiments was to understand kinetic <span class="hlt">exchange</span> rates and develop parameters for use in Iġnik Sikumi history match simulations. The experimental procedure involves two main stages: 1) the formation of CH4 hydrate in a consolidated sand column at 750 psi and 2°C and 2) flow-through of a 77.5/22.5 N2/CO2 molar ratio <span class="hlt">gas</span> mixture across the column. Experiments were run both above and below the hydrate stability zone in order to observe <span class="hlt">exchange</span> behavior across varying conditions. The numerical simulator, STOMP-HYDT-KE, was then used to match experimental results, specifically fitting kinetic behavior. Once this behavior is understood, it can be applied to field scale models based on Ignik Sikumi #1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20050000492&hterms=copd&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcopd','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20050000492&hterms=copd&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcopd"><span>Alveolar ventilation to perfusion heterogeneity and diffusion impairment in a mathematical model of <span class="hlt">gas</span> <span class="hlt">exchange</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vidal Melo, M. F.; Loeppky, J. A.; Caprihan, A.; Luft, U. C.</p> <p>1993-01-01</p> <p>This study describes a two-compartment model of pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> in which alveolar ventilation to perfusion (VA/Q) heterogeneity and impairment of pulmonary diffusing capacity (D) are simultaneously taken into account. The mathematical model uses as input data measurements usually obtained in the lung function laboratory. It consists of two compartments and an anatomical shunt. Each compartment receives fractions of alveolar ventilation and blood flow. Mass balance equations and integration of Fick's law of diffusion are used to compute alveolar and blood O2 and CO2 values compatible with input O2 uptake and CO2 elimination. Two applications are presented. The first is a method to partition O2 and CO2 alveolar-arterial gradients into VA/Q and D components. The technique is evaluated in data of patients with chronic obstructive pulmonary disease (COPD). The second is a theoretical analysis of the effects of blood flow variation in alveolar and blood O2 partial pressures. The results show the importance of simultaneous consideration of D to estimate VA/Q heterogeneity in patients with diffusion impairment. This factor plays an increasing role in <span class="hlt">gas</span> alveolar-arterial gradients as severity of COPD increases. Association of VA/Q heterogeneity and D may produce an increase of O2 arterial pressure with decreasing QT which would not be observed if only D were considered. We conclude that the presented computer model is a useful tool for description and interpretation of data from COPD patients and for performing theoretical analysis of variables involved in the <span class="hlt">gas</span> <span class="hlt">exchange</span> process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018LSSR...16...47V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018LSSR...16...47V"><span>Estimating CO2 <span class="hlt">gas</span> <span class="hlt">exchange</span> in mixed age vegetable plant communities grown on soil-like substrates for life support systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Velichko, V. V.; Tikhomirov, A. A.; Ushakova, S. A.</p> <p>2018-02-01</p> <p>If soil-like substrate (SLS) is to be used in human life support systems with a high degree of mass closure, the rate of its <span class="hlt">gas</span> <span class="hlt">exchange</span> as a compartment for mineralization of plant biomass should be understood. The purpose of this study was to compare variations in CO2 <span class="hlt">gas</span> <span class="hlt">exchange</span> of vegetable plant communities grown on the soil-like substrate using a number of plant age groups, which determined the so-called conveyor interval. Two experimental plant communities were grown as plant conveyors with different conveyor intervals. The first plant community consisted of conveyors with intervals of 7 days for carrot and beet and 14 days for chufa sedge. The conveyor intervals in the second plant community were 14 days for carrot and beet and 28 days for chufa sedge. This study showed that increasing the number of age groups in the conveyor and, thus, increasing the frequency of adding plant waste to the SLS, decreased the range of variations in CO2 concentration in the "plant-soil-like substrate" system. However, the resultant CO2 <span class="hlt">gas</span> <span class="hlt">exchange</span> was shifted towards CO2 release to the atmosphere of the plant community with short conveyor intervals. The duration of the conveyor interval did not significantly affect productivity and mineral composition of plants grown on the SLS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3541132','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3541132"><span>Combined Effects of Ventilation Mode and Positive End-Expiratory Pressure on Mechanics, <span class="hlt">Gas</span> <span class="hlt">Exchange</span> and the Epithelium in Mice with Acute Lung Injury</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Thammanomai, Apiradee; Hamakawa, Hiroshi; Bartolák-Suki, Erzsébet; Suki, Béla</p> <p>2013-01-01</p> <p>The accepted protocol to ventilate patients with acute lung injury is to use low tidal volume (VT) in combination with recruitment maneuvers or positive end-expiratory pressure (PEEP). However, an important aspect of mechanical ventilation has not been considered: the combined effects of PEEP and ventilation modes on the integrity of the epithelium. Additionally, it is implicitly assumed that the best PEEP-VT combination also protects the epithelium. We aimed to investigate the effects of ventilation mode and PEEP on respiratory mechanics, peak airway pressures and <span class="hlt">gas</span> <span class="hlt">exchange</span> as well as on lung surfactant and epithelial cell integrity in mice with acute lung injury. HCl-injured mice were ventilated at PEEPs of 3 and 6 cmH2O with conventional ventilation (CV), CV with intermittent large breaths (CVLB) to promote recruitment, and a new mode, variable ventilation, optimized for mice (VVN). Mechanics and <span class="hlt">gas</span> <span class="hlt">exchange</span> were measured during ventilation and surfactant protein (SP)-B, proSP-B and E-cadherin levels were determined from lavage and lung homogenate. PEEP had a significant effect on mechanics, <span class="hlt">gas</span> <span class="hlt">exchange</span> and the epithelium. The higher PEEP reduced lung collapse and improved mechanics and <span class="hlt">gas</span> <span class="hlt">exchange</span> but it also down regulated surfactant release and production and increased epithelial cell injury. While CVLB was better than CV, VVN outperformed CVLB in recruitment, reduced epithelial injury and, via a dynamic mechanotransduction, it also triggered increased release and production of surfactant. For long-term outcome, selection of optimal PEEP and ventilation mode may be based on balancing lung physiology with epithelial injury. PMID:23326543</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18849091','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18849091"><span>Juvenile Rhus glabra leaves have higher temperatures and lower <span class="hlt">gas</span> <span class="hlt">exchange</span> rates than mature leaves when compared in the field during periods of high irradiance.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Snider, John L; Choinski, John S; Wise, Robert R</p> <p>2009-05-01</p> <p>We sought to test the hypothesis that stomatal development determines the timing of <span class="hlt">gas</span> <span class="hlt">exchange</span> competency, which then influences leaf temperature through transpirationally driven leaf cooling. To test this idea, daily patterns of <span class="hlt">gas</span> <span class="hlt">exchange</span> and leaflet temperature were obtained from leaves of two distinctively different developmental stages of smooth sumac (Rhus glabra) grown in its native habitat. Juvenile and mature leaves were also sampled for ultrastructural studies of stomatal development. When plants were sampled in May-June, the hypothesis was supported: juvenile leaflets were (for part of the day) from 1.4 to 6.0 degrees C warmer than mature leaflets and as much as 2.0 degrees C above ambient air temperature with lower stomatal conductance and photosynthetic rates than mature leaflets. When measurements were taken from July to October, no significant differences were observed, although mature leaflet <span class="hlt">gas</span> <span class="hlt">exchange</span> rates declined to the levels of the juvenile leaves. The <span class="hlt">gas</span> <span class="hlt">exchange</span> data were supported by the observations that juvenile leaves had approximately half the number of functional stomata on a leaf surface area basis as did mature leaves. It was concluded that leaf temperature and stage of leaf development in sumac are strongly linked with the higher surface temperatures observed in juvenile leaflets in the early spring possibly being involved in promoting photosynthesis and leaf expansion when air temperatures are cooler.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012Cryo...52..642C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012Cryo...52..642C"><span>Effect of multi-stream heat <span class="hlt">exchanger</span> on performance of natural <span class="hlt">gas</span> liquefaction with mixed refrigerant</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chang, Ho-Myung; Lim, Hye Su; Choe, Kun Hyung</p> <p>2012-12-01</p> <p>A thermodynamic study is carried out to investigate the effect of multi-stream heat <span class="hlt">exchanger</span> on the performance of natural <span class="hlt">gas</span> (NG) liquefaction with mixed refrigerant (MR). A cold stream (low-pressure MR) is in thermal contact with opposite flow of two hot streams (high-pressure MR and NG feed) at the same time. In typical process simulation with commercial software (such as Aspen HYSYS®), the liquefaction performance is estimated with a method of minimum temperature approach, simply assuming that two hot streams have the same temperature. In this study, local energy balance equations are rigorously solved with temperature-dependent properties of MR and NG feed, and are linked to the thermodynamic cycle analysis. The figure of merit (FOM) is quantitatively examined in terms of UA (the product of overall heat transfer coefficient and heat <span class="hlt">exchange</span> area) between respective streams. In a single-stage MR process, it is concluded that the temperature profile from HYSYS is difficult to realize in practice, and the FOM value from HYSYS is an over-estimate, but can be closely achieved with a proper heat-<span class="hlt">exchanger</span> design. It is also demonstrated that there exists a unique optimal ratio in three UA's, and no direct heat <span class="hlt">exchanger</span> between hot streams is recommended.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5388163','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5388163"><span><span class="hlt">Exchange</span> Bias Optimization by Controlled Oxidation of Cobalt Nanoparticle Films Prepared by Sputter <span class="hlt">Gas</span> Aggregation</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Antón, Ricardo López; González, Juan A.; Andrés, Juan P.; Normile, Peter S.; Canales-Vázquez, Jesús; Muñiz, Pablo; Riveiro, José M.; De Toro, José A.</p> <p>2017-01-01</p> <p>Porous films of cobalt nanoparticles have been obtained by sputter <span class="hlt">gas</span> aggregation and controllably oxidized by air annealing at 100 °C for progressively longer times (up to more than 1400 h). The magnetic properties of the samples were monitored during the process, with a focus on the <span class="hlt">exchange</span> bias field. Air annealing proves to be a convenient way to control the Co/CoO ratio in the samples, allowing the optimization of the <span class="hlt">exchange</span> bias field to a value above 6 kOe at 5 K. The occurrence of the maximum in the <span class="hlt">exchange</span> bias field is understood in terms of the density of CoO uncompensated spins and their degree of pinning, with the former reducing and the latter increasing upon the growth of a progressively thicker CoO shell. Vertical shifts exhibited in the magnetization loops are found to correlate qualitatively with the peak in the <span class="hlt">exchange</span> bias field, while an increase in vertical shift observed for longer oxidation times may be explained by a growing fraction of almost completely oxidized particles. The presence of a hummingbird-like form in magnetization loops can be understood in terms of a combination of hard (biased) and soft (unbiased) components; however, the precise origin of the soft phase is as yet unresolved. PMID:28336895</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28336895','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28336895"><span><span class="hlt">Exchange</span> Bias Optimization by Controlled Oxidation of Cobalt Nanoparticle Films Prepared by Sputter <span class="hlt">Gas</span> Aggregation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Antón, Ricardo López; González, Juan A; Andrés, Juan P; Normile, Peter S; Canales-Vázquez, Jesús; Muñiz, Pablo; Riveiro, José M; De Toro, José A</p> <p>2017-03-11</p> <p>Porous films of cobalt nanoparticles have been obtained by sputter <span class="hlt">gas</span> aggregation and controllably oxidized by air annealing at 100 °C for progressively longer times (up to more than 1400 h). The magnetic properties of the samples were monitored during the process, with a focus on the <span class="hlt">exchange</span> bias field. Air annealing proves to be a convenient way to control the Co/CoO ratio in the samples, allowing the optimization of the <span class="hlt">exchange</span> bias field to a value above 6 kOe at 5 K. The occurrence of the maximum in the <span class="hlt">exchange</span> bias field is understood in terms of the density of CoO uncompensated spins and their degree of pinning, with the former reducing and the latter increasing upon the growth of a progressively thicker CoO shell. Vertical shifts exhibited in the magnetization loops are found to correlate qualitatively with the peak in the <span class="hlt">exchange</span> bias field, while an increase in vertical shift observed for longer oxidation times may be explained by a growing fraction of almost completely oxidized particles. The presence of a hummingbird-like form in magnetization loops can be understood in terms of a combination of hard (biased) and soft (unbiased) components; however, the precise origin of the soft phase is as yet unresolved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15557031','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15557031"><span>The hyperoxic switch: assessing respiratory water loss rates in tracheate arthropods with continuous <span class="hlt">gas</span> <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lighton, John R B; Schilman, Pablo E; Holway, David A</p> <p>2004-12-01</p> <p>Partitioning the relative contributions of cuticular and respiratory water loss in a tracheate arthropod is relatively easy if it undergoes discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> cycles or DGCs, leaving its rate of cuticular water loss in primary evidence while its spiracles are closed. Many arthropods are not so obliging and emit CO(2) continuously, making cuticular and respiratory water losses difficult or impossible to partition. We report here that by switching ambient air from 21 to 100% O(2), marked spiracular constriction takes place, causing a transient but substantial - up to 90% - reduction in CO(2) output. A reduction in water loss rate occurs at the same time. Using this approach, we investigated respiratory water loss in Drosophila melanogaster and in two ant species, Forelius mccooki and Pogonomyrmex californicus. Our results - respiratory water loss estimates of 23%, 7.6% and 5.6% of total water loss rates, respectively - are reasonable in light of literature estimates, and suggest that the 'hyperoxic switch' may allow straightforward estimation of respiratory water loss rates in arthropods lacking discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span>. In P. californicus, which we were able to measure with and without a DGC, presence or absence of a DGC did not affect respiratory vs total water loss rates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26710629','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26710629"><span>[Effects of different water potentials on leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and chlorophyll fluorescence parameters of cucumber during post-flowering growth stage].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lin, Lu; Tang, Yun; Zhang, Ji-tao; Yan, Wan-li; Xiao, Jian-hong; Ding, Chao; Dong, Chuan; Ji, Zeng-shun</p> <p>2015-07-01</p> <p>Impacts of different substrate water potentials (SWP) on leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and chlorophyll fluorescence parameters of greenhouse cucumber during its post-flowering growth stage were analyzed in this study. The results demonstrated that -10 and -30 kPa were the critical values for initiating stomatal and non-stomatal limitation of drought stress, respectively. During the stage of no drought stress (-10 kPa < SWP ≤ 0 kPa), <span class="hlt">gas</span> <span class="hlt">exchange</span> parameters and chlorophyll fluorescence parameters were not different significantly among treatments. During the stage of stomatal limitation of drought stress (-30 kPa<SWP ≤ -10 kPa), with the decrease of SWP, the stomatal conductance (gs), intercellular carbon dioxide concentration (Ci), net photosynthetic rate (Pn) , apparent quantum efficiency (ε), transpiration rate (Tr), carboxylation efficiency (CE), maximum Rubisco-limited rate of carboxylation (Vc max), maximum rate of electron transport (Jmax), rate of triosephosphate utilization (VTPU), maximum and actual quantum efficiency of PSII (ΦPSII, and Fv/Fm) and photochemical quenching (qP) decreased, but the light compensation point (LCP), dark respiration rate (Rd), carbon dioxide compensation point (CCP), stomatal limitation value (LS), instantaneous water use efficiency (WUEi) and non-photochemical quenching (qN) increased. In this stage, <span class="hlt">gas</span> <span class="hlt">exchange</span> parameters changed faster than chlorophyll fluorescence parameters and differed significantly among treatments. During the stage of non-stomatal limitation of drought stress (-45 kPa≤SWP ≤ -30 kPa), with the decrease of SWP, light saturation point (LSP), Rd, CE, Vcmax, VTPU, LS, WUEi, ΦpPSII, Fv/Fm and qp decreased, while CCP, Ci and qN increased. In this stage, chlorophyll fluorescence parameters changed faster than <span class="hlt">gas</span> <span class="hlt">exchange</span> parameters and differed significantly among treatments. In production of greenhouse cucumber, -10 and -5 kPa should be the lower and upper limit value of irrigation, respectively. The stomatal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16498531','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16498531"><span>Heat and moisture <span class="hlt">exchangers</span> and heated humidifiers in acute lung injury/acute respiratory distress syndrome patients. Effects on respiratory mechanics and <span class="hlt">gas</span> <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Morán, Indalecio; Bellapart, Judith; Vari, Alessandra; Mancebo, Jordi</p> <p>2006-04-01</p> <p>To compare, in acute lung injury/acute respiratory distress syndrome (ALI/ARDS) patients, the short-term effects of heat and moisture <span class="hlt">exchangers</span> (HME) and heated humidifiers (HH) on <span class="hlt">gas</span> <span class="hlt">exchange</span>, and also on respiratory system mechanics when isocapnic conditions are met. Prospective open clinical study. Intensive Care Service. Seventeen invasively ventilated ALI/ARDS patients. The study was performed in three phases: (1) determinations were made during basal ventilatory settings with HME; (2) basal ventilatory settings were maintained and HME was replaced by an HH; (3) using the same HH, tidal volume (Vt) was decreased until basal PaCO2 levels were reached. FiO2, respiratory rate and PEEP were kept unchanged. Respiratory mechanics, Vdphys, <span class="hlt">gas</span> <span class="hlt">exchange</span> and hemodynamic parameters were obtained at each phase. By using HH instead of HME and without changing Vt, PaCO2 decreased from 46+/-9 to 40+/-8 mmHg (p<0.001) and Vdphys decreased from 352+/-63 to 310+/-74 ml (p<0.001). Comparing the first phase with the third, Vt decreased from 521+/-106 to 440+/-118 ml (p<0.001) without significant changes in PaCO2, Vd/Vt decreased from 0.69+/-0.11 to 0.62+/-0.12 (p<0.001), plateau airway pressure decreased from 25+/-6 to 21+/-6 cmH2O (p<0.001) and respiratory system compliance improved from 35+/-12 to 42+/-15 ml/cmH2O (p<0.001). PaO2 remained unchanged in the three phases. Reducing dead space with the use of HH decreases PaCO2 and more importantly, if isocapnic conditions are maintained by reducing Vt, this strategy improves respiratory system compliance and reduces plateau airway pressure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4725048','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4725048"><span>Effect of transjugular intrahepatic portosystemic shunt on pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> in patients with portal hypertension and hepatopulmonary syndrome</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Martínez-Pallí, Graciela; Drake, Britt B; García-Pagán, Joan-Carles; Barberà, Joan-Albert; Arguedas, Miguel R; Rodriguez-Roisin, Robert; Bosch, Jaume; Fallon, Michael B</p> <p>2005-01-01</p> <p>AIM: To assess the impact of transjugular intrahepatic portosystemic shunt (TIPS) on pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> and to evaluate the use of TIPS for the treatment of hepatopulmonary syndrome ( HPS ). METHODS: Seven patients, three of them with advanced HPS, in whom detailed pulmonary function tests were performed before and after TIPS placement at the University of Alabama Hospital and at the Hospital Clinic, Barcelona, were considered. RESULTS: TIPS patency was confirmed by hemodynamic evaluation. No changes in arterial blood gases were observed in the overall subset of patients. Transient arterial oxygenation improvement was observed in only one HPS patient, early after TIPS, but this was not sustained 4 mo later. CONCLUSION: TIPS neither improved nor worsened pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> in patients with portal hypertension. This data does not support the use of TIPS as a specific treatment for HPS. However, it does reinforce the view that TIPS can be safely performed for the treatment of other complications of portal hypertension in patients with HPS. PMID:16425397</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910008007','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910008007"><span>Heat transfer in a compact tubular heat <span class="hlt">exchanger</span> with helium <span class="hlt">gas</span> at 3.5 MPa</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Olson, Douglas A.; Glover, Michael P.</p> <p>1990-01-01</p> <p>A compact heat <span class="hlt">exchanger</span> was constructed consisting of circular tubes in parallel brazed to a grooved base plate. This tube specimen heat <span class="hlt">exchanger</span> was tested in an apparatus which radiatively heated the specimen on one side at a heat flux of up to 54 W/sq cm, and cooled the specimen with helium <span class="hlt">gas</span> at 3.5 MPa and Reynolds numbers of 3000 to 35,000. The measured friction factor of the tube specimen was lower than that of a circular tube with fully developed turbulent flow, although the uncertainty was high due to entrance and exit losses. The measured Nusselt number, when modified to account for differences in fluid properties between the wall and the cooling fluid, agreed with past correlations for fully developed turbulent flow in circular tubes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19422714','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19422714"><span>Effect of sedation with detomidine and butorphanol on pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> in the horse.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nyman, Görel; Marntell, Stina; Edner, Anna; Funkquist, Pia; Morgan, Karin; Hedenstierna, Göran</p> <p>2009-05-07</p> <p>Sedation with alpha2-agonists in the horse is reported to be accompanied by impairment of arterial oxygenation. The present study was undertaken to investigate pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> using the Multiple Inert <span class="hlt">Gas</span> Elimination Technique (MIGET), during sedation with the alpha2-agonist detomidine alone and in combination with the opioid butorphanol. Seven Standardbred trotter horses aged 3-7 years and weighing 380-520 kg, were studied. The protocol consisted of three consecutive measurements; in the unsedated horse, after intravenous administration of detomidine (0.02 mg/kg) and after subsequent butorphanol administration (0.025 mg/kg). Pulmonary function and haemodynamic effects were investigated. The distribution of ventilation-perfusion ratios (VA/Q) was estimated with MIGET. During detomidine sedation, arterial oxygen tension (PaO2) decreased (12.8 +/- 0.7 to 10.8 +/- 1.2 kPa) and arterial carbon dioxide tension (PaCO2) increased (5.9 +/- 0.3 to 6.1 +/- 0.2 kPa) compared to measurements in the unsedated horse. Mismatch between ventilation and perfusion in the lungs was evident, but no increase in intrapulmonary shunt could be detected. Respiratory rate and minute ventilation did not change. Heart rate and cardiac output decreased, while pulmonary and systemic blood pressure and vascular resistance increased. Addition of butorphanol resulted in a significant decrease in ventilation and increase in PaCO2. Alveolar-arterial oxygen content difference P(A-a)O2 remained impaired after butorphanol administration, the VA/Q distribution improved as the decreased ventilation and persistent low blood flow was well matched. Also after subsequent butorphanol no increase in intrapulmonary shunt was evident. The results of the present study suggest that both pulmonary and cardiovascular factors contribute to the impaired pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> during detomidine and butorphanol sedation in the horse.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2694811','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2694811"><span>Effect of sedation with detomidine and butorphanol on pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> in the horse</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nyman, Görel; Marntell, Stina; Edner, Anna; Funkquist, Pia; Morgan, Karin; Hedenstierna, Göran</p> <p>2009-01-01</p> <p>Background Sedation with α2-agonists in the horse is reported to be accompanied by impairment of arterial oxygenation. The present study was undertaken to investigate pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> using the Multiple Inert <span class="hlt">Gas</span> Elimination Technique (MIGET), during sedation with the α2-agonist detomidine alone and in combination with the opioid butorphanol. Methods Seven Standardbred trotter horses aged 3–7 years and weighing 380–520 kg, were studied. The protocol consisted of three consecutive measurements; in the unsedated horse, after intravenous administration of detomidine (0.02 mg/kg) and after subsequent butorphanol administration (0.025 mg/kg). Pulmonary function and haemodynamic effects were investigated. The distribution of ventilation-perfusion ratios (VA/Q) was estimated with MIGET. Results During detomidine sedation, arterial oxygen tension (PaO2) decreased (12.8 ± 0.7 to 10.8 ± 1.2 kPa) and arterial carbon dioxide tension (PaCO2) increased (5.9 ± 0.3 to 6.1 ± 0.2 kPa) compared to measurements in the unsedated horse. Mismatch between ventilation and perfusion in the lungs was evident, but no increase in intrapulmonary shunt could be detected. Respiratory rate and minute ventilation did not change. Heart rate and cardiac output decreased, while pulmonary and systemic blood pressure and vascular resistance increased. Addition of butorphanol resulted in a significant decrease in ventilation and increase in PaCO2. Alveolar-arterial oxygen content difference P(A-a)O2 remained impaired after butorphanol administration, the VA/Q distribution improved as the decreased ventilation and persistent low blood flow was well matched. Also after subsequent butorphanol no increase in intrapulmonary shunt was evident. Conclusion The results of the present study suggest that both pulmonary and cardiovascular factors contribute to the impaired pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> during detomidine and butorphanol sedation in the horse. PMID:19422714</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhyA..469..323F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhyA..469..323F"><span>Long memory of <span class="hlt">abnormal</span> investor attention and the cross-correlations between <span class="hlt">abnormal</span> investor attention and trading volume, volatility respectively</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fan, Xiaoqian; Yuan, Ying; Zhuang, Xintian; Jin, Xiu</p> <p>2017-03-01</p> <p>Taking Baidu Index as a proxy for <span class="hlt">abnormal</span> investor attention (AIA), the long memory property in the AIA of Shanghai Stock <span class="hlt">Exchange</span> (SSE) 50 Index component stocks was empirically investigated using detrended fluctuation analysis (DFA) method. The results show that <span class="hlt">abnormal</span> investor attention is power-law correlated with Hurst exponents between 0.64 and 0.98. Furthermore, the cross-correlations between <span class="hlt">abnormal</span> investor attention and trading volume, volatility respectively are studied using detrended cross-correlation analysis (DCCA) and the DCCA cross-correlation coefficient (ρDCCA). The results suggest that there are positive correlations between AIA and trading volume, volatility respectively. In addition, the correlations for trading volume are in general higher than the ones for volatility. By carrying on rescaled range analysis (R/S) and rolling windows analysis, we find that the results mentioned above are effective and significant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/39792','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/39792"><span>Growth, <span class="hlt">gas</span> <span class="hlt">exchange</span>, foliar nitrogen content, and water use of subirrigated and overhead irrigated Populus tremuloides Michx. seedlings</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Anthony S. Davis; Matthew M. Aghai; Jeremiah R. Pinto; Kent G. Apostal</p> <p>2011-01-01</p> <p>Because limitations on water used by container nurseries has become commonplace, nursery growers will have to improve irrigation management. Subirrigation systems may provide an alternative to overhead irrigation systems by mitigating groundwater pollution and excessive water consumption. Seedling growth, <span class="hlt">gas</span> <span class="hlt">exchange</span>, leaf nitrogen (N) content, and water use were...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2826656','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2826656"><span>Modulating the light environment with the peach ‘asymmetric orchard’: effects on <span class="hlt">gas</span> <span class="hlt">exchange</span> performances, photoprotection, and photoinhibition</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Losciale, Pasquale; Chow, Wah Soon; Corelli Grappadelli, Luca</p> <p>2010-01-01</p> <p>The productivity of fruit trees is a linear function of the light intercepted, although the relationship is less tight when greater than 50% of available light is intercepted. This paper investigates the management of light energy in peach using the measurement of whole-tree light interception and <span class="hlt">gas</span> <span class="hlt">exchange</span>, along with the absorbed energy partitioning at the leaf level by concurrent measurements of <span class="hlt">gas</span> <span class="hlt">exchange</span> and chlorophyll fluorescence. These measurements were performed on trees of a custom-built ‘asymmetric’ orchard. Whole-tree <span class="hlt">gas</span> <span class="hlt">exchange</span> for north–south, vertical canopies (C) was similar to that for canopies intercepting the highest irradiance in the morning hours (W), but trees receiving the highest irradiance in the afternoon (E) had the highest net photosynthesis and transpiration while maintaining a water use efficiency (WUE) comparable to the other treatments. In the W trees, 29% and 8% more photosystems were damaged than in C and E trees, respectively. The quenching partitioning revealed that the non-photochemical quenching (NPQ) played the most important role in excess energy dissipation, but it was not fully active at low irradiance, possibly due to a sub-optimal trans-thylakoid ΔpH. The non-net carboxylative mechanisms (NC) appeared to be the main photoprotective mechanisms at low irradiance levels and, probably, they could facilitate the establishment of a trans-thylakoid ΔpH more appropriate for NPQ. These findings support the conclusion that irradiance impinging on leaves may be excessive and can cause photodamage, whose repair requires energy in the form of carbohydrates that are thereby diverted from tree growth and productivity. PMID:20124356</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=309153','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=309153"><span>Weak coordination among petiole, leaf, vein, and <span class="hlt">gas-exchange</span> traits across 41 Australian angiosperm species and its possible implications</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Background and Aims Close coordination between leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and maximal hydraulic supply has been reported across diverse plant life-forms. However, recent reports suggest that this relationship may become weak or break down completely within the angiosperms. Methods To examine this possi...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1174314','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1174314"><span>Oscillating side-branch enhancements of thermoacoustic heat <span class="hlt">exchangers</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Swift, Gregory W.</p> <p>2003-05-13</p> <p>A regenerator-based engine or refrigerator has a regenerator with two ends at two different temperatures, through which a <span class="hlt">gas</span> oscillates at a first oscillating volumetric flow rate in the direction between the two ends and in which the pressure of the <span class="hlt">gas</span> oscillates, and first and second heat <span class="hlt">exchangers</span>, each of which is at one of the two different temperatures. A dead-end side branch into which the <span class="hlt">gas</span> oscillates has compliance and is connected adjacent to one of the ends of the regenerator to form a second oscillating <span class="hlt">gas</span> flow rate additive with the first oscillating volumetric flow rate, the compliance having a volume effective to provide a selected total oscillating <span class="hlt">gas</span> volumetric flow rate through the first heat <span class="hlt">exchanger</span>. This configuration enables the first heat <span class="hlt">exchanger</span> to be configured and located to better enhance the performance of the heat <span class="hlt">exchanger</span> rather than being confined to the location and configuration of the regenerator.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26170097','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26170097"><span>A novel pump-driven veno-venous <span class="hlt">gas</span> <span class="hlt">exchange</span> system during extracorporeal CO2-removal.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hermann, Alexander; Riss, Katharina; Schellongowski, Peter; Bojic, Andja; Wohlfarth, Philipp; Robak, Oliver; Sperr, Wolfgang R; Staudinger, Thomas</p> <p>2015-10-01</p> <p>Pump-driven veno-venous extracorporeal CO2-removal (ECCO2-R) increasingly takes root in hypercapnic lung failure to minimize ventilation invasiveness or to avoid intubation. A recently developed device (iLA activve(®), Novalung, Germany) allows effective decarboxylation via a 22 French double lumen cannula. To assess determinants of <span class="hlt">gas</span> <span class="hlt">exchange</span>, we prospectively evaluated the performance of ECCO2-R in ten patients receiving iLA activve(®) due to hypercapnic respiratory failure. Sweep <span class="hlt">gas</span> flow was increased in steps from 1 to 14 L/min at constant blood flow (phase 1). Similarly, blood flow was gradually increased at constant sweep <span class="hlt">gas</span> flow (phase 2). At each step <span class="hlt">gas</span> transfer via the membrane as well as arterial blood <span class="hlt">gas</span> samples were analyzed. During phase 1, we observed a significant increase in CO2 transfer together with a decrease in PaCO2 levels from a median of 66 mmHg (range 46-85) to 49 (31-65) mmHg from 1 to 14 L/min sweep <span class="hlt">gas</span> flow (p < 0.0001), while arterial oxygenation deteriorated with high sweep <span class="hlt">gas</span> flow rates. During phase 2, oxygen transfer significantly increased leading to an increase in PaO2 from 67 (49-87) at 0.5 L/min to 117 (66-305) mmHg at 2.0 L/min (p < 0.0001). Higher blood flows also significantly enhanced decarboxylation (p < 0.0001). Increasing sweep <span class="hlt">gas</span> flow results in effective CO2-removal, which can be further reinforced by raising blood flow. The clinically relevant oxygenation effect in this setting could broaden the range of indications of the system and help to set up an individually tailored configuration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/874378','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/874378"><span>Heat <span class="hlt">exchanger</span> with transpired, highly porous fins</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Kutscher, Charles F.; Gawlik, Keith</p> <p>2002-01-01</p> <p>The heat <span class="hlt">exchanger</span> includes a fin and tube assembly with increased heat transfer surface area positioned within a hollow chamber of a housing to provide effective heat transfer between a <span class="hlt">gas</span> flowing within the hollow chamber and a fluid flowing in the fin and tube assembly. A fan is included to force a <span class="hlt">gas</span>, such as air, to flow through the hollow chamber and through the fin and tube assembly. The fin and tube assembly comprises fluid conduits to direct the fluid through the heat <span class="hlt">exchanger</span>, to prevent mixing with the <span class="hlt">gas</span>, and to provide a heat transfer surface or pathway between the fluid and the <span class="hlt">gas</span>. A heat transfer element is provided in the fin and tube assembly to provide extended heat transfer surfaces for the fluid conduits. The heat transfer element is corrugated to form fins between alternating ridges and grooves that define flow channels for directing the <span class="hlt">gas</span> flow. The fins are fabricated from a thin, heat conductive material containing numerous orifices or pores for transpiring the <span class="hlt">gas</span> out of the flow channel. The grooves are closed or only partially open so that all or substantially all of the <span class="hlt">gas</span> is transpired through the fins so that heat is <span class="hlt">exchanged</span> on the front and back surfaces of the fins and also within the interior of the orifices, thereby significantly increasing the available the heat transfer surface of the heat <span class="hlt">exchanger</span>. The transpired fins also increase heat transfer effectiveness of the heat <span class="hlt">exchanger</span> by increasing the heat transfer coefficient by disrupting boundary layer development on the fins and by establishing other beneficial <span class="hlt">gas</span> flow patterns, all at desirable pressure drops.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ACP....17.9019B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ACP....17.9019B"><span>Estimation of bubble-mediated air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> from concurrent DMS and CO2 transfer velocities at intermediate-high wind speeds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bell, Thomas G.; Landwehr, Sebastian; Miller, Scott D.; de Bruyn, Warren J.; Callaghan, Adrian H.; Scanlon, Brian; Ward, Brian; Yang, Mingxi; Saltzman, Eric S.</p> <p>2017-07-01</p> <p>Simultaneous air-sea fluxes and concentration differences of dimethylsulfide (DMS) and carbon dioxide (CO2) were measured during a summertime North Atlantic cruise in 2011. This data set reveals significant differences between the <span class="hlt">gas</span> transfer velocities of these two gases (Δkw) over a range of wind speeds up to 21 m s-1. These differences occur at and above the approximate wind speed threshold when waves begin breaking. Whitecap fraction (a proxy for bubbles) was also measured and has a positive relationship with Δkw, consistent with enhanced bubble-mediated transfer of the less soluble CO2 relative to that of the more soluble DMS. However, the correlation of Δkw with whitecap fraction is no stronger than with wind speed. Models used to estimate bubble-mediated transfer from in situ whitecap fraction underpredict the observations, particularly at intermediate wind speeds. Examining the differences between <span class="hlt">gas</span> transfer velocities of gases with different solubilities is a useful way to detect the impact of bubble-mediated <span class="hlt">exchange</span>. More simultaneous <span class="hlt">gas</span> transfer measurements of different solubility gases across a wide range of oceanic conditions are needed to understand the factors controlling the magnitude and scaling of bubble-mediated <span class="hlt">gas</span> <span class="hlt">exchange</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.P21A0220H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.P21A0220H"><span>Laboratory Measurements of Oxygen <span class="hlt">Gas</span> Release from Basaltic Minerals Exposed to UV- Radiation: Implications for the Viking <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hurowitz, J. A.; Yen, A. S.</p> <p>2007-12-01</p> <p>The biology experiments onboard the Viking Landers determined that the Martian soils at Chryse and Utopia Planitia contain an unknown chemical compound of a highly oxidizing nature. The <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Experiments (GEx) demonstrated that the humidification of a 1-cc Martian soil sample resulted in the production of as much as 790 nanomoles of oxygen <span class="hlt">gas</span>. Yen et al. (2000) have provided experimental evidence that superoxide radicals can be generated on plagioclase feldspar (labradorite) grain surfaces by exposure to ultraviolet (UV) light in the presence of oxygen <span class="hlt">gas</span>. Adsorbed superoxide radicals are thought to react readily with water vapor, and produce oxygen <span class="hlt">gas</span> in quantities sufficient to explain the Viking GEx results. Direct evidence for the formation of oxygen <span class="hlt">gas</span>, however, was not provided in the experiments of Yen et al (2000). Accordingly, the motivation of this study is to determine whether superoxide radicals adsorbed on labradorite surfaces are capable of producing oxygen <span class="hlt">gas</span> upon exposure to water vapor. We have constructed an experimental apparatus that is capable of monitoring oxygen <span class="hlt">gas</span> release from basaltic mineral powders that have been exposed to UV-radiation under Martian atmospheric pressure conditions. The apparatus consists of a stainless-steel vacuum chamber with a UV- transparent window where sample radiation exposures are performed. The vacuum chamber has multiple valved ports for injection of gases and water vapor. The vacuum chamber is connected via a precision leak valve to a quadrupole mass spectrometer, which measures changes in the composition of the headspace gases over our mineral samples. We will report on the results of our experiments, which are aimed at detecting and quantifying oxygen <span class="hlt">gas</span> release from UV-exposed basaltic mineral samples using this new experimental facility. These results will further constrain whether superoxide ions adsorbed on mineral surfaces provide a viable explanation for the Viking GEx results, which have</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=291531','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=291531"><span>Asymmetrical effects of mesophyll conductance on fundamental photosynthetic parameters and their relationships estimated from leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> measurements</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Most previous analyses of leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> measurements assumed an infinite value of mesophyll conductance (gm) and thus equaled CO2 partial pressures in the substomatal cavity and chloroplast. Yet an increasing number of studies have recognized that gm is finite and there is a drawdown of CO2 part...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26391334','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26391334"><span>A dynamic leaf <span class="hlt">gas-exchange</span> strategy is conserved in woody plants under changing ambient CO2 : evidence from carbon isotope discrimination in paleo and CO2 enrichment studies.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Voelker, Steven L; Brooks, J Renée; Meinzer, Frederick C; Anderson, Rebecca; Bader, Martin K-F; Battipaglia, Giovanna; Becklin, Katie M; Beerling, David; Bert, Didier; Betancourt, Julio L; Dawson, Todd E; Domec, Jean-Christophe; Guyette, Richard P; Körner, Christian; Leavitt, Steven W; Linder, Sune; Marshall, John D; Mildner, Manuel; Ogée, Jérôme; Panyushkina, Irina; Plumpton, Heather J; Pregitzer, Kurt S; Saurer, Matthias; Smith, Andrew R; Siegwolf, Rolf T W; Stambaugh, Michael C; Talhelm, Alan F; Tardif, Jacques C; Van de Water, Peter K; Ward, Joy K; Wingate, Lisa</p> <p>2016-02-01</p> <p>Rising atmospheric [CO2 ], ca , is expected to affect stomatal regulation of leaf <span class="hlt">gas-exchange</span> of woody plants, thus influencing energy fluxes as well as carbon (C), water, and nutrient cycling of forests. Researchers have proposed various strategies for stomatal regulation of leaf <span class="hlt">gas-exchange</span> that include maintaining a constant leaf internal [CO2 ], ci , a constant drawdown in CO2 (ca  - ci ), and a constant ci /ca . These strategies can result in drastically different consequences for leaf <span class="hlt">gas-exchange</span>. The accuracy of Earth systems models depends in part on assumptions about generalizable patterns in leaf <span class="hlt">gas-exchange</span> responses to varying ca . The concept of optimal stomatal behavior, exemplified by woody plants shifting along a continuum of these strategies, provides a unifying framework for understanding leaf <span class="hlt">gas-exchange</span> responses to ca . To assess leaf <span class="hlt">gas-exchange</span> regulation strategies, we analyzed patterns in ci inferred from studies reporting C stable isotope ratios (δ(13) C) or photosynthetic discrimination (∆) in woody angiosperms and gymnosperms that grew across a range of ca spanning at least 100 ppm. Our results suggest that much of the ca -induced changes in ci /ca occurred across ca spanning 200 to 400 ppm. These patterns imply that ca  - ci will eventually approach a constant level at high ca because assimilation rates will reach a maximum and stomatal conductance of each species should be constrained to some minimum level. These analyses are not consistent with canalization toward any single strategy, particularly maintaining a constant ci . Rather, the results are consistent with the existence of a broadly conserved pattern of stomatal optimization in woody angiosperms and gymnosperms. This results in trees being profligate water users at low ca , when additional water loss is small for each unit of C gain, and increasingly water-conservative at high ca , when photosystems are saturated and water loss is large for each unit C gain. </p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70178114','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70178114"><span>A dynamic leaf <span class="hlt">gas-exchange</span> strategy is conserved in woody plants under changing ambient CO2: evidence from carbon isotope discrimination in paleo and CO2 enrichment studies</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Voelker, Steven L.; Brooks, J. Renée; Meinzer, Frederick C.; Anderson, Rebecca D.; Bader, Martin K.-F.; Battipaglia, Giovanna; Becklin, Katie M.; Beerling, David; Bert, Didier; Betancourt, Julio L.; Dawson, Todd E.; Domec, Jean-Christophe; Guyette, Richard P.; Körner, Christian; Leavitt, Steven W.; Linder, Sune; Marshall, John D.; Mildner, Manuel; Ogée, Jérôme; Panyushkina, Irina P.; Plumpton, Heather J.; Pregitzer, Kurt S.; Saurer, Matthias; Smith, Andrew R.; Siegwolf, Rolf T.W.; Stambaugh, Michael C.; Talhelm, Alan F.; Tardif, Jacques C.; Van De Water, Peter K.; Ward, Joy K.; Wingate, Lisa</p> <p>2016-01-01</p> <p>Rising atmospheric [CO2], ca, is expected to affect stomatal regulation of leaf <span class="hlt">gas-exchange</span> of woody plants, thus influencing energy fluxes as well as carbon (C), water, and nutrient cycling of forests. Researchers have proposed various strategies for stomatal regulation of leaf <span class="hlt">gas-exchange</span> that include maintaining a constant leaf internal [CO2], ci, a constant drawdown in CO2(ca − ci), and a constant ci/ca. These strategies can result in drastically different consequences for leaf <span class="hlt">gas-exchange</span>. The accuracy of Earth systems models depends in part on assumptions about generalizable patterns in leaf <span class="hlt">gas-exchange</span> responses to varying ca. The concept of optimal stomatal behavior, exemplified by woody plants shifting along a continuum of these strategies, provides a unifying framework for understanding leaf <span class="hlt">gas-exchange</span> responses to ca. To assess leaf <span class="hlt">gas-exchange</span> regulation strategies, we analyzed patterns in ci inferred from studies reporting C stable isotope ratios (δ13C) or photosynthetic discrimination (∆) in woody angiosperms and gymnosperms that grew across a range of ca spanning at least 100 ppm. Our results suggest that much of the ca-induced changes in ci/ca occurred across ca spanning 200 to 400 ppm. These patterns imply that ca − ci will eventually approach a constant level at high ca because assimilation rates will reach a maximum and stomatal conductance of each species should be constrained to some minimum level. These analyses are not consistent with canalization toward any single strategy, particularly maintaining a constant ci. Rather, the results are consistent with the existence of a broadly conserved pattern of stomatal optimization in woody angiosperms and gymnosperms. This results in trees being profligate water users at low ca, when additional water loss is small for each unit of C gain, and increasingly water-conservative at high ca, when photosystems are saturated and water loss is large for each unit C gain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/865635','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/865635"><span>Flue <span class="hlt">gas</span> desulfurization</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Im, Kwan H.; Ahluwalia, Rajesh K.</p> <p>1985-01-01</p> <p>A process and apparatus for removing sulfur oxide from combustion <span class="hlt">gas</span> to form Na.sub.2 SO.sub.4 and for reducing the harmful effects of Na.sub.2 SO.sub.4 on auxiliary heat <span class="hlt">exchangers</span> in which a sodium compound is injected into the hot combustion <span class="hlt">gas</span> forming liquid Na.sub.2 SO.sub.4 in a <span class="hlt">gas-gas</span> reaction and the resultant <span class="hlt">gas</span> containing Na.sub.2 SO.sub.4 is cooled to below about 1150.degree. K. to form particles of Na.sub.2 SO.sub.4 prior to contact with at least one heat <span class="hlt">exchanger</span> with the cooling being provided by the recycling of combustion <span class="hlt">gas</span> from a cooled zone downstream from the introduction of the cooling <span class="hlt">gas</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18973832','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18973832"><span>Estimating the effect of lung collapse and pulmonary shunt on <span class="hlt">gas</span> <span class="hlt">exchange</span> during breath-hold diving: the Scholander and Kooyman legacy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fahlman, A; Hooker, S K; Olszowka, A; Bostrom, B L; Jones, D R</p> <p>2009-01-01</p> <p>We developed a mathematical model to investigate the effect of lung compression and collapse (pulmonary shunt) on the uptake and removal of O(2), CO(2) and N(2) in blood and tissue of breath-hold diving mammals. We investigated the consequences of pressure (diving depth) and respiratory volume on pulmonary shunt and <span class="hlt">gas</span> <span class="hlt">exchange</span> as pressure compressed the alveoli. The model showed good agreement with previous studies of measured arterial O(2) tensions (Pa(O)(2)) from freely diving Weddell seals and measured arterial and venous N(2) tensions from captive elephant seals compressed in a hyperbaric chamber. Pulmonary compression resulted in a rapid spike in Pa(O)(2) and arterial CO(2) tension, followed by cyclical variation with a periodicity determined by Q(tot). The model showed that changes in diving lung volume are an efficient behavioural means to adjust the extent of <span class="hlt">gas</span> <span class="hlt">exchange</span> with depth. Differing models of lung compression and collapse depth caused major differences in blood and tissue N(2) estimates. Our integrated modelling approach contradicted predictions from simple models, and emphasised the complex nature of physiological interactions between circulation, lung compression and <span class="hlt">gas</span> <span class="hlt">exchange</span>. Overall, our work suggests the need for caution in interpretation of previous model results based on assumed collapse depths and all-or-nothing lung collapse models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22319207','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22319207"><span>Quantitative variation in water-use efficiency across water regimes and its relationship with circadian, vegetative, reproductive, and leaf <span class="hlt">gas-exchange</span> traits.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Edwards, Christine E; Ewers, Brent E; McClung, C Robertson; Lou, Ping; Weinig, Cynthia</p> <p>2012-05-01</p> <p>Drought limits light harvesting, resulting in lower plant growth and reproduction. One trait important for plant drought response is water-use efficiency (WUE). We investigated (1) how the joint genetic architecture of WUE, reproductive characters, and vegetative traits changed across drought and well-watered conditions, (2) whether traits with distinct developmental bases (e.g. leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> versus reproduction) differed in the environmental sensitivity of their genetic architecture, and (3) whether quantitative variation in circadian period was related to drought response in Brassica rapa. Overall, WUE increased in drought, primarily because stomatal conductance, and thus water loss, declined more than carbon fixation. Genotypes with the highest WUE in drought expressed the lowest WUE in well-watered conditions, and had the largest vegetative and floral organs in both treatments. Thus, large changes in WUE enabled some genotypes to approach vegetative and reproductive trait optima across environments. The genetic architecture differed for <span class="hlt">gas-exchange</span> and vegetative traits across drought and well-watered conditions, but not for floral traits. Correlations between circadian and leaf <span class="hlt">gas-exchange</span> traits were significant but did not vary across treatments, indicating that circadian period affects physiological function regardless of water availability. These results suggest that WUE is important for drought tolerance in Brassica rapa and that artificial selection for increased WUE in drought will not result in maladaptive expression of other traits that are correlated with WUE.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27147352','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27147352"><span>Quantification of regional early stage <span class="hlt">gas</span> <span class="hlt">exchange</span> changes using hyperpolarized (129)Xe MRI in a rat model of radiation-induced lung injury.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Doganay, Ozkan; Stirrat, Elaine; McKenzie, Charles; Schulte, Rolf F; Santyr, Giles E</p> <p>2016-05-01</p> <p>To assess the feasibility of hyperpolarized (HP) (129)Xe MRI for detection of early stage radiation-induced lung injury (RILI) in a rat model involving unilateral irradiation by assessing differences in <span class="hlt">gas</span> <span class="hlt">exchange</span> dynamics between irradiated and unirradiated lungs. The dynamics of <span class="hlt">gas</span> <span class="hlt">exchange</span> between alveolar air space and pulmonary tissue (PT), PT and red blood cells (RBCs) was measured using single-shot spiral iterative decomposition of water and fat with echo asymmetry and least-squares estimation images of the right and left lungs of two age-matched cohorts of Sprague Dawley rats. The first cohort (n = 5) received 18 Gy irradiation to the right lung using a (60)Co source and the second cohort (n = 5) was not irradiated and served as the healthy control. Both groups were imaged two weeks following irradiation when radiation pneumonitis (RP) was expected to be present. The <span class="hlt">gas</span> <span class="hlt">exchange</span> data were fit to a theoretical <span class="hlt">gas</span> <span class="hlt">exchange</span> model to extract measurements of pulmonary tissue thickness (LPT) and relative blood volume (VRBC) from each of the right and left lungs of both cohorts. Following imaging, lung specimens were retrieved and percent tissue area (PTA) was assessed histologically to confirm RP and correlate with MRI measurements. Statistically significant differences in LPT and VRBC were observed between the irradiated and non-irradiated cohorts. In particular, LPT of the right and left lungs was increased approximately 8.2% and 5.0% respectively in the irradiated cohort. Additionally, VRBC of the right and left lungs was decreased approximately 36.1% and 11.7% respectively for the irradiated cohort compared to the non-irradiated cohort. PTA measurements in both right and left lungs were increased in the irradiated group compared to the non-irradiated cohort for both the left (P < 0.05) and right lungs (P < 0.01) confirming the presence of RP. PTA measurements also correlated with the MRI measurements for both the non-irradiated (r = 0.79, P < 0.01) and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3718390','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3718390"><span>Atmospheric concentrations and air–soil <span class="hlt">gas</span> <span class="hlt">exchange</span> of polycyclic aromatic hydrocarbons (PAHs) in remote, rural village and urban areas of Beijing–Tianjin region, North China</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wang, Wentao; Simonich, Staci; Giri, Basant; Chang, Ying; Zhang, Yuguang; Jia, Yuling; Tao, Shu; Wang, Rong; Wang, Bin; Li, Wei; Cao, Jun; Lu, Xiaoxia</p> <p>2013-01-01</p> <p>Forty passive air samplers were deployed to study the occurrence of <span class="hlt">gas</span> and particulate phase PAHs in remote, rural village and urban areas of Beijing–Tianjin region, North China for four seasons (spring, summer, fall and winter) from 2007 to 2008. The influence of emissions on the spatial distribution pattern of air PAH concentrations was addressed. In addition, the air–soil <span class="hlt">gas</span> <span class="hlt">exchange</span> of PAHs was studied using fugacity calculations. The median gaseous and particulate phase PAH concentrations were 222 ng/m3 and 114 ng/m3, respectively, with a median total PAH concentration of 349 ng/m3. Higher PAH concentrations were measured in winter than in other seasons. Air PAH concentrations measured at the rural villages and urban sites in the northern mountain region were significantly lower than those measured at sites in the southern plain during all seasons. However, there was no significant difference in PAH concentrations between the rural villages and urban sites in the northern and southern areas. This urban–rural PAH distribution pattern was related to the location of PAH emission sources and the population distribution. The location of PAH emission sources explained 56%–77% of the spatial variation in ambient air PAH concentrations. The annual median air–soil <span class="hlt">gas</span> <span class="hlt">exchange</span> flux of PAHs was 42.2 ng/m2/day from soil to air. Among the 15 PAHs measured, acenaphthylene (ACY) and acenaphthene (ACE) contributed to more than half of the total <span class="hlt">exchange</span> flux. Furthermore, the air–soil <span class="hlt">gas</span> <span class="hlt">exchange</span> fluxes of PAHs at the urban sites were higher than those at the remote and rural sites. In summer, more gaseous PAHs volatilized from soil to air because of higher temperatures and increased rainfall. However, in winter, more gaseous PAHs deposited from air to soil due to higher PAH emissions and lower temperatures. The soil TOC concentration had no significant influence on the air–soil <span class="hlt">gas</span> <span class="hlt">exchange</span> of PAHs. PMID:21669328</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21669328','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21669328"><span>Atmospheric concentrations and air-soil <span class="hlt">gas</span> <span class="hlt">exchange</span> of polycyclic aromatic hydrocarbons (PAHs) in remote, rural village and urban areas of Beijing-Tianjin region, North China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Wentao; Simonich, Staci; Giri, Basant; Chang, Ying; Zhang, Yuguang; Jia, Yuling; Tao, Shu; Wang, Rong; Wang, Bin; Li, Wei; Cao, Jun; Lu, Xiaoxia</p> <p>2011-07-01</p> <p>Forty passive air samplers were deployed to study the occurrence of <span class="hlt">gas</span> and particulate phase PAHs in remote, rural village and urban areas of Beijing-Tianjin region, North China for four seasons (spring, summer, fall and winter) from 2007 to 2008. The influence of emissions on the spatial distribution pattern of air PAH concentrations was addressed. In addition, the air-soil <span class="hlt">gas</span> <span class="hlt">exchange</span> of PAHs was studied using fugacity calculations. The median gaseous and particulate phase PAH concentrations were 222 ng/m³ and 114 ng/m³, respectively, with a median total PAH concentration of 349 ng/m³. Higher PAH concentrations were measured in winter than in other seasons. Air PAH concentrations measured at the rural villages and urban sites in the northern mountain region were significantly lower than those measured at sites in the southern plain during all seasons. However, there was no significant difference in PAH concentrations between the rural villages and urban sites in the northern and southern areas. This urban-rural PAH distribution pattern was related to the location of PAH emission sources and the population distribution. The location of PAH emission sources explained 56%-77% of the spatial variation in ambient air PAH concentrations. The annual median air-soil <span class="hlt">gas</span> <span class="hlt">exchange</span> flux of PAHs was 42.2 ng/m²/day from soil to air. Among the 15 PAHs measured, acenaphthylene (ACY) and acenaphthene (ACE) contributed to more than half of the total <span class="hlt">exchange</span> flux. Furthermore, the air-soil <span class="hlt">gas</span> <span class="hlt">exchange</span> fluxes of PAHs at the urban sites were higher than those at the remote and rural sites. In summer, more gaseous PAHs volatilized from soil to air because of higher temperatures and increased rainfall. However, in winter, more gaseous PAHs deposited from air to soil due to higher PAH emissions and lower temperatures. The soil TOC concentration had no significant influence on the air-soil <span class="hlt">gas</span> <span class="hlt">exchange</span> of PAHs. Copyright © 2011 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28152260','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28152260"><span>Thermal dissociation of ions limits the degree of the <span class="hlt">gas</span>-phase H/D <span class="hlt">exchange</span> at the atmospheric pressure.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kostyukevich, Y; Kononikhin, A; Popov, I; Nikolaev, E</p> <p>2017-04-01</p> <p>We present the application of the extended desolvating capillaries for increasing the degree of the <span class="hlt">gas</span>-phase hydrogen/deuterium <span class="hlt">exchange</span> reaction at atmospheric pressure. The use of the extended capillaries results in the increase of the time that ions spend in the high pressure region, what leads to the significant improvement of the efficiency of the reaction. For the small protein ubiquitin, it was observed that for the same temperature, the number of <span class="hlt">exchanges</span> increases with the decrease of the charge state so that the lowest charge state can <span class="hlt">exchange</span> twice the number of hydrogen than the highest one. With the increase of the temperature, the difference decreases, and eventually, the number of <span class="hlt">exchanges</span> equalizes for all charge states. The value of this temperature and the corresponding number of <span class="hlt">exchanges</span> depend on the geometric parameters of the capillary. Further increase of the temperature leads to the thermal dissociation of the protein ion. The observed b/y fragments are identical to those produced by collision-induced dissociation performed in the ion trap. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29386224','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29386224"><span>Intricate but tight coupling of spiracular activity and abdominal ventilation during locust discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> cycles.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Talal, Stav; Gefen, Eran; Ayali, Amir</p> <p>2018-03-15</p> <p>Discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> (DGE) is the best studied among insect <span class="hlt">gas</span> <span class="hlt">exchange</span> patterns. DGE cycles comprise three phases, which are defined by their spiracular state: closed, flutter and open. However, spiracle status has rarely been monitored directly; rather, it is often assumed based on CO 2 emission traces. In this study, we directly recorded electromyogram (EMG) signals from the closer muscle of the second thoracic spiracle and from abdominal ventilation muscles in a fully intact locust during DGE. Muscular activity was monitored simultaneously with CO 2 emission, under normoxia and under various experimental oxic conditions. Our findings indicate that locust DGE does not correspond well with the commonly described three-phase cycle. We describe unique DGE-related ventilation motor patterns, coupled to spiracular activity. During the open phase, when CO 2 emission rate is highest, the thoracic spiracles do not remain open; rather, they open and close rapidly. This fast spiracle activity coincides with in-phase abdominal ventilation, while alternating with the abdominal spiracle and thus facilitating a unidirectional air flow along the main trachea. A change in the frequency of rhythmic ventilation during the open phase suggests modulation by intra-tracheal CO 2 levels. A second, slow ventilatory movement pattern probably serves to facilitate <span class="hlt">gas</span> diffusion during spiracle closure. Two flutter-like patterns are described in association with the different types of ventilatory activity. We offer a modified mechanistic model for DGE in actively ventilating insects, incorporating ventilatory behavior and changes in spiracle state. © 2018. Published by The Company of Biologists Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19210642','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19210642"><span>Effects of tree height on branch hydraulics, leaf structure and <span class="hlt">gas</span> <span class="hlt">exchange</span> in California redwoods.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ambrose, Anthony R; Sillett, Stephen C; Dawson, Todd E</p> <p>2009-07-01</p> <p>We examined changes in branch hydraulic, leaf structure and <span class="hlt">gas</span> <span class="hlt">exchange</span> properties in coast redwood (Sequoia sempervirens) and giant sequoia (Sequoiadendron giganteum) trees of different sizes. Leaf-specific hydraulic conductivity (k(L)) increased with height in S. sempervirens but not in S. giganteum, while xylem cavitation resistance increased with height in both species. Despite hydraulic adjustments, leaf mass per unit area (LMA) and leaf carbon isotope ratios (delta(13)C) increased, and maximum mass-based stomatal conductance (g(mass)) and photosynthesis (A(mass)) decreased with height in both species. As a result, both A(mass) and g(mass) were negatively correlated with branch hydraulic properties in S. sempervirens and uncorrelated in S. giganteum. In addition, A(mass) and g(mass) were negatively correlated with LMA in both species, which we attributed to the effects of decreasing leaf internal CO(2) conductance (g(i)). Species-level differences in wood density, LMA and area-based <span class="hlt">gas</span> <span class="hlt">exchange</span> capacity constrained other structural and physiological properties, with S. sempervirens exhibiting increased branch water transport efficiency and S. giganteum exhibiting increased leaf-level water-use efficiency with increasing height. Our results reveal different adaptive strategies for the two redwoods that help them compensate for constraints associated with growing taller, and reflect contrasting environmental conditions each species faces in its native habitat.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20709922','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20709922"><span>Phenotypic plasticity of <span class="hlt">gas</span> <span class="hlt">exchange</span> pattern and water loss in Scarabaeus spretus (Coleoptera: Scarabaeidae): deconstructing the basis for metabolic rate variation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Terblanche, John S; Clusella-Trullas, Susana; Chown, Steven L</p> <p>2010-09-01</p> <p>Investigation of <span class="hlt">gas</span> <span class="hlt">exchange</span> patterns and modulation of metabolism provide insight into metabolic control systems and evolution in diverse terrestrial environments. Variation in metabolic rate in response to environmental conditions has been explained largely in the context of two contrasting hypotheses, namely metabolic depression in response to stressful or resource-(e.g. water) limited conditions, or elevation of metabolism at low temperatures to sustain life in extreme conditions. To deconstruct the basis for metabolic rate changes in response to temperature variation, here we undertake a full factorial study investigating the longer- and short-term effects of temperature exposure on <span class="hlt">gas</span> <span class="hlt">exchange</span> patterns. We examined responses of traits of <span class="hlt">gas</span> <span class="hlt">exchange</span> [standard metabolic rate (SMR); discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> (DGE) cycle frequency; cuticular, respiratory and total water loss rate (WLR)] to elucidate the magnitude and form of plastic responses in the dung beetle, Scarabaeus spretus. Results showed that short- and longer-term temperature variation generally have significant effects on SMR and WLR. Overall, acclimation to increased temperature led to a decline in SMR (from 0.071+/-0.004 ml CO(2) h(-1) in 15 degrees C-acclimated beetles to 0.039+/-0.004 ml CO(2) h(-1) in 25 degrees C-acclimated beetles measured at 20 degrees C) modulated by reduced DGE frequency (15 degrees C acclimation: 0.554+/-0.027 mHz, 20 degrees C acclimation: 0.257+/-0.030 mHz, 25 degrees C acclimation: 0.208+/-0.027 mHz recorded at 20 degrees C), reduced cuticular WLRs (from 1.058+/-0.537 mg h(-1) in 15 degrees C-acclimated beetles to 0.900+/-0.400 mg h(-1) in 25 degrees C-acclimated beetles measured at 20 degrees C) and reduced total WLR (from 4.2+/-0.5 mg h(-1) in 15 degrees C-acclimated beetles to 3.1+/-0.5 mg h(-1) in 25 degrees C-acclimated beetles measured at 25 degrees C). Respiratory WLR was reduced from 2.25+/-0.40 mg h(-1) in 15 degrees C-acclimated beetles to 1.60+/-0.40 mg h</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008APS..MARJ17010M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008APS..MARJ17010M"><span>Dynamics of <span class="hlt">Gas</span> <span class="hlt">Exchange</span> through the Fractal Architecture of the Human Lung, Modeled as an Exactly Solvable Hierarchical Tree</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mayo, Michael; Pfeifer, Peter; Gheorghiu, Stefan</p> <p>2008-03-01</p> <p>The acinar airways lie at the periphery of the human lung and are responsible for the transfer of oxygen from air to the blood during respiration. This transfer occurs by the diffusion-reaction of oxygen over the irregular surface of the alveolar membranes lining the acinar airways. We present an exactly solvable diffusion-reaction model on a hierarchically branched tree, allowing a quantitative prediction of the oxygen current over the entire system of acinar airways responsible for the <span class="hlt">gas</span> <span class="hlt">exchange</span>. We discuss the effect of diffusional screening, which is strongly coupled to oxygen transport in the human lung. We show that the oxygen current is insensitive to a loss of permeability of the alveolar membranes over a wide range of permeabilities, similar to a ``constant-current source'' in an electric network. Such fault tolerance has been observed in other treatments of the <span class="hlt">gas</span> <span class="hlt">exchange</span> in the lung and is obtained here as a fully analytical result.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16666773','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16666773"><span>Whole Plant and Leaf Steady State <span class="hlt">Gas</span> <span class="hlt">Exchange</span> during Ethylene Exposure in Xanthium strumarium L.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Woodrow, L; Jiao, J; Tsujita, M J; Grodzinski, B</p> <p>1989-05-01</p> <p>The effects of ethylene evolved from ethephon on leaf and whole plant photosynthesis in Xanthium strumarium L. were examined. Ethylene-induced epinasty reduced light interception by the leaves of ethephon treated plants by up to 60%. <span class="hlt">Gas</span> <span class="hlt">exchange</span> values of individual, attached leaves under identical assay conditions were not inhibited even after 36 hours of ethylene exposure, although treated leaves required a longer induction period to achieve steady state photosynthesis. The speed of translocation of recently fixed (11)C-assimilate movement was not seriously impaired following ethephon treatment; however, a greater proportion of the assimilate was partitioned downward toward the roots. Within 24 hours of ethephon treatment, the whole plant net carbon <span class="hlt">exchange</span> rate expressed on a per plant basis or a leaf area basis had dropped by 35%. The apparent inhibition of net carbon <span class="hlt">exchange</span> rate was reversed by physically repositioning the leaves with respect to the light source. Ethylene exposure also inhibited expansion of young leaves which was partially reversed when the leaves were repositioned. The data indicated that ethylene indirectly affected net C gain and plant growth through modification of light interception and altered sink demand without directly inhibiting leaf photosynthesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009APS..MARX13012G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009APS..MARX13012G"><span><span class="hlt">Exchange</span> Energy Density Functionals that reproduce the Linear Response Function of the Free Electron <span class="hlt">Gas</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>García-Aldea, David; Alvarellos, J. E.</p> <p>2009-03-01</p> <p>We present several nonlocal <span class="hlt">exchange</span> energy density functionals that reproduce the linear response function of the free electron <span class="hlt">gas</span>. These nonlocal functionals are constructed following a similar procedure used previously for nonlocal kinetic energy density functionals by Chac'on-Alvarellos-Tarazona, Garc'ia-Gonz'alez et al., Wang-Govind-Carter and Garc'ia-Aldea-Alvarellos. The <span class="hlt">exchange</span> response function is not known but we have used the approximate response function developed by Utsumi and Ichimaru, even we must remark that the same ansatz can be used to reproduce any other response function with the same scaling properties. We have developed two families of new nonlocal functionals: one is constructed with a mathematical structure based on the LDA approximation -- the Dirac functional for the <span class="hlt">exchange</span> - and for the second one the structure of the second order gradient expansion approximation is took as a model. The functionals are constructed is such a way that they can be used in localized systems (using real space calculations) and in extended systems (using the momentum space, and achieving a quasilinear scaling with the system size if a constant reference electron density is defined).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013BGeo...10.5793S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013BGeo...10.5793S"><span>Biology and air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> controls on the distribution of carbon isotope ratios (δ13C) in the ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schmittner, A.; Gruber, N.; Mix, A. C.; Key, R. M.; Tagliabue, A.; Westberry, T. K.</p> <p>2013-09-01</p> <p>Analysis of observations and sensitivity experiments with a new three-dimensional global model of stable carbon isotope cycling elucidate processes that control the distribution of δ13C of dissolved inorganic carbon (DIC) in the contemporary and preindustrial ocean. Biological fractionation and the sinking of isotopically light δ13C organic matter from the surface into the interior ocean leads to low δ13CDIC values at depths and in high latitude surface waters and high values in the upper ocean at low latitudes with maxima in the subtropics. Air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> has two effects. First, it acts to reduce the spatial gradients created by biology. Second, the associated temperature-dependent fractionation tends to increase (decrease) δ13CDIC values of colder (warmer) water, which generates gradients that oppose those arising from biology. Our model results suggest that both effects are similarly important in influencing surface and interior δ13CDIC distributions. However, since air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> is slow in the modern ocean, the biological effect dominates spatial δ13CDIC gradients both in the interior and at the surface, in contrast to conclusions from some previous studies. Calcium carbonate cycling, pH dependency of fractionation during air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span>, and kinetic fractionation have minor effects on δ13CDIC. Accumulation of isotopically light carbon from anthropogenic fossil fuel burning has decreased the spatial variability of surface and deep δ13CDIC since the industrial revolution in our model simulations. Analysis of a new synthesis of δ13CDIC measurements from years 1990 to 2005 is used to quantify preformed and remineralized contributions as well as the effects of biology and air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span>. The model reproduces major features of the observed large-scale distribution of δ13CDIC as well as the individual contributions and effects. Residual misfits are documented and analyzed. Simulated surface and subsurface δ13CDIC are influenced by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010004211','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010004211"><span>BOREAS TE-4 <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Data from Boreal Tree Species</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Collatz, G. James; Berry, Joseph A.; Gamon, John; Fredeen, Art; Fu, Wei</p> <p>2000-01-01</p> <p>The BOREAS TE-4 team collected steady-state <span class="hlt">gas</span> <span class="hlt">exchange</span> and reflectance data from several species in the BOREAS SSA during 1994 and in the NSA during 1996. Measurements of light, CO2, temperature, and humidity response curves were made by the BOREAS TE-4 team during the summers of 1994 and 1996 using intact attached leaves of boreal forest species located in the BOREAS SSA and NSA. These measurements were conducted to calibrate models used to predict photosynthesis, stomatal conductance, and leaf respiration. The 1994 and 1996 data can be used to construct plots of response functions or for parameterizing models. Parameter values are suitable for application in SiB2 (Sellers et al., 1996) or the leaf model of Collatz et al. (1991), and programs can be obtained from the investigators. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080000771','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080000771"><span>What can be Learned from X-ray Spectroscopy Concerning Hot <span class="hlt">Gas</span> in Local Bubble and Charge <span class="hlt">Exchange</span> Processes?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Snowden, Steve</p> <p>2007-01-01</p> <p>What can be learned from x-ray spectroscopy in observing hot <span class="hlt">gas</span> in local bubble and charge <span class="hlt">exchange</span> processes depends on spectral resolution, instrumental grasp, instrumental energy band, signal-to-nose, field of view, angular resolution and observatory location. Early attempts at x-ray spectroscopy include ROSAT; more recently, astronomers have used diffuse x-ray spectrometers, XMM Newton, sounding rocket calorimeters, and Suzaku. Future observations are expected with calorimeters on the Spectrum Roentgen Gamma mission, and the Solar Wind Charge <span class="hlt">Exchange</span> (SWCX). The Geospheric SWCX may provide remote sensing of the solar wind and magnetosheath and remote observations of solar CMEs moving outward from the sun.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JASMS..29..230M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JASMS..29..230M"><span>Ion Mobility Spectrometry-Mass Spectrometry Coupled with <span class="hlt">Gas</span>-Phase Hydrogen/Deuterium <span class="hlt">Exchange</span> for Metabolomics Analyses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maleki, Hossein; Karanji, Ahmad K.; Majuta, Sandra; Maurer, Megan M.; Valentine, Stephen J.</p> <p>2018-02-01</p> <p>Ion mobility spectrometry-mass spectrometry (IMS-MS) in combination with <span class="hlt">gas</span>-phase hydrogen/deuterium <span class="hlt">exchange</span> (HDX) and collision-induced dissociation (CID) is evaluated as an analytical method for small-molecule standard and mixture characterization. Experiments show that compound ions exhibit unique HDX reactivities that can be used to distinguish different species. Additionally, it is shown that <span class="hlt">gas</span>-phase HDX kinetics can be exploited to provide even further distinguishing capabilities by using different partial pressures of reagent <span class="hlt">gas</span>. The relative HDX reactivity of a wide variety of molecules is discussed in light of the various molecular structures. Additionally, hydrogen accessibility scoring (HAS) and HDX kinetics modeling of candidate ( in silico) ion structures is utilized to estimate the relative ion conformer populations giving rise to specific HDX behavior. These data interpretation methods are discussed with a focus on developing predictive tools for HDX behavior. Finally, an example is provided in which ion mobility information is supplemented with HDX reactivity data to aid identification efforts of compounds in a metabolite extract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A43G2558W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A43G2558W"><span>Air-sea <span class="hlt">exchange</span> and <span class="hlt">gas</span>-particle partitioning of polycyclic aromatic hydrocarbons over the northwestern Pacific Ocean: Role of East Asian continental outflow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Z.; Guo, Z.</p> <p>2017-12-01</p> <p>We measured 15 parent polycyclic aromatic hydrocarbons (PAHs) in atmosphere and water during a research cruise from the East China Sea (ECS) to the northwestern Pacific Ocean (NWP) in the spring of 2015 to investigate the occurrence, air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span>, and <span class="hlt">gas</span>-particle partitioning of PAHs with a particular focus on the influence of East Asian continental outflow. The gaseous PAH composition and identification of sources were consistent with PAHs from the upwind area, indicating that the gaseous PAHs (three- to five-ring PAHs) were influenced by upwind land pollution. In addition, air-sea <span class="hlt">exchange</span> fluxes of gaseous PAHs were estimated to be -54.2 to 107.4 ng m-2 d-1, and was indicative of variations of land-based PAH inputs. The logarithmic <span class="hlt">gas</span>-particle partition coefficient (logKp) of PAHs regressed linearly against the logarithmic subcooled liquid vapor pressure, with a slope of -0.25. This was significantly larger than the theoretical value (-1), implying disequilibrium between the gaseous and particulate PAHs over the NWP. The non-equilibrium of PAH <span class="hlt">gas</span>-particle partitioning was shielded from the volatilization of three-ring gaseous PAHs from seawater and lower soot concentrations in particular when the oceanic air masses prevailed. Modeling PAH absorption into organic matter and adsorption onto soot carbon revealed that the status of PAH <span class="hlt">gas</span>-particle partitioning deviated more from the modeling Kp for oceanic air masses than those for continental air masses, which coincided with higher volatilization of three-ring PAHs and confirmed the influence of air-sea <span class="hlt">exchange</span>. Meanwhile, significant linear regressions between logKp and logKoa (logKsa) for PAHs were observed for continental air masses, suggesting the dominant effect of East Asian continental outflow on atmospheric PAHs over the NWP during the sampling campaign.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25063854','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25063854"><span>A hierarchy of factors influence discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> in the grasshopper Paracinema tricolor (Orthoptera: Acrididae).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Groenewald, Berlizé; Chown, Steven L; Terblanche, John S</p> <p>2014-10-01</p> <p>The evolutionary origin and maintenance of discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> (DGE) in tracheate arthropods are poorly understood and highly controversial. We investigated prioritization of abiotic factors in the <span class="hlt">gas</span> <span class="hlt">exchange</span> control cascade by examining oxygen, water and haemolymph pH regulation in the grasshopper Paracinema tricolor. Using a full-factorial design, grasshoppers were acclimated to hypoxic or hyperoxic (5% O2, 40% O2) <span class="hlt">gas</span> conditions, or dehydrated or hydrated, whereafter their CO2 release was measured under a range of O2 and relative humidity (RH) conditions (5%, 21%, 40% O2 and 5%, 60%, 90% RH). DGE was significantly less common in grasshoppers acclimated to dehydrating conditions compared with the other acclimations (hypoxia, 98%; hyperoxia, 100%; hydrated, 100%; dehydrated, 67%). Acclimation to dehydrating conditions resulted in a significant decrease in haemolymph pH from 7.0±0.3 to 6.6±0.1 (mean ± s.d., P=0.018) and also significantly increased the open (O)-phase duration under 5% O2 treatment conditions (5% O2, 44.1±29.3 min; 40% O2, 15.8±8.0 min; 5% RH, 17.8±1.3 min; 60% RH, 24.0±9.7 min; 90% RH, 20.6±8.9 min). The observed acidosis could potentially explain the extension of the O-phase under low RH conditions, when it would perhaps seem more useful to reduce the O-phase to lower respiratory water loss. The results confirm that DGE occurrence and modulation are affected by multiple abiotic factors. A hierarchical framework for abiotic factors influencing DGE is proposed in which the following stressors are prioritized in decreasing order of importance: oxygen supply, CO2 excretion and pH modulation, oxidative damage protection and water savings. © 2014. Published by The Company of Biologists Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/55311','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/55311"><span>Stomatal kinetics and photosynthetic <span class="hlt">gas</span> <span class="hlt">exchange</span> along a continuum of isohydric to anisohydric regulation of plant water status</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Frederick C. Meinzer; Duncan D. Smith; David R. Woodruff; Danielle E. Marias; Katherine A. McCulloh; Ava R. Howard; Alicia L. Magedman</p> <p>2017-01-01</p> <p>Species’ differences in the stringency of stomatal control of plant water potential represent a continuum of isohydric to anisohydric behaviours. However, little is known about how quasi-steady-state stomatal regulation of water potential may relate to dynamic behaviour of stomata and photosynthetic <span class="hlt">gas</span> <span class="hlt">exchange</span> in species operating at different positions along this...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/952467','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/952467"><span>Recovery of Water from Boiler Flue <span class="hlt">Gas</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Edward Levy; Harun Bilirgen; Kwangkook Jeong</p> <p>2008-09-30</p> <p>This project dealt with use of condensing heat <span class="hlt">exchangers</span> to recover water vapor from flue <span class="hlt">gas</span> at coal-fired power plants. Pilot-scale heat transfer tests were performed to determine the relationship between flue <span class="hlt">gas</span> moisture concentration, heat <span class="hlt">exchanger</span> design and operating conditions, and water vapor condensation rate. The tests also determined the extent to which the condensation processes for water and acid vapors in flue <span class="hlt">gas</span> can be made to occur separately in different heat transfer sections. The results showed flue <span class="hlt">gas</span> water vapor condensed in the low temperature region of the heat <span class="hlt">exchanger</span> system, with water capture efficiencies depending stronglymore » on flue <span class="hlt">gas</span> moisture content, cooling water inlet temperature, heat <span class="hlt">exchanger</span> design and flue <span class="hlt">gas</span> and cooling water flow rates. Sulfuric acid vapor condensed in both the high temperature and low temperature regions of the heat transfer apparatus, while hydrochloric and nitric acid vapors condensed with the water vapor in the low temperature region. Measurements made of flue <span class="hlt">gas</span> mercury concentrations upstream and downstream of the heat <span class="hlt">exchangers</span> showed a significant reduction in flue <span class="hlt">gas</span> mercury concentration within the heat <span class="hlt">exchangers</span>. A theoretical heat and mass transfer model was developed for predicting rates of heat transfer and water vapor condensation and comparisons were made with pilot scale measurements. Analyses were also carried out to estimate how much flue <span class="hlt">gas</span> moisture it would be practical to recover from boiler flue <span class="hlt">gas</span> and the magnitude of the heat rate improvements which could be made by recovering sensible and latent heat from flue <span class="hlt">gas</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16123205','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16123205"><span>Pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> is not impaired 24 h after extravehicular activity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Prisk, G Kim; Fine, Janelle M; Cooper, Trevor K; West, John B</p> <p>2005-12-01</p> <p>Extravehicular activity (EVA) during spaceflight involves a significant decompression stress. Previous studies have shown an increase in the inhomogeneity of ventilation-perfusion ratio (VA/Q) after some underwater dives, presumably through the embolic effects of venous <span class="hlt">gas</span> microemboli in the lung. Ground-based chamber studies simulating EVA have shown that venous <span class="hlt">gas</span> microemboli occur in a large percentage of the subjects undergoing decompression, despite the use of prebreathe protocols to reduce dissolved N(2) in the tissues. We studied eight crewmembers (7 male, 1 female) of the International Space Station who performed 15 EVAs (initial cabin pressure 748 mmHg, final suit pressure either approximately 295 or approximately 220 mmHg depending on the suit used) and who followed the denitrogenation procedures approved for EVA from the International Space Station. The intrabreath VA/Q slope was calculated from the alveolar Po(2) and Pco(2) in a prolonged exhalation maneuver on the day after EVA and compared with measurements made in microgravity on days well separated from the EVA. There were no significant changes in intrabreath VA/Q slope as a result of EVA, although there was a slight increase in metabolic rate and ventilation (approximately 9%) on the day after EVA. Vital capacity and other measures of pulmonary function were largely unaltered by EVA. Because measurements could only be performed on the day after EVA because of logistical constraints, we were unable to determine an acute effect of EVA on VA/Q inequality. The results suggest that current denitrogenation protocols do not result in any major lasting alteration to <span class="hlt">gas</span> <span class="hlt">exchange</span> in the lung.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70047811','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70047811"><span>Leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and nutrient use efficiency help explain the distribution of two Neotropical mangroves under contrasting flooding and salinity</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Cardona-Olarte, Pablo; Krauss, Ken W.; Twilley, Robert R.</p> <p>2013-01-01</p> <p>Rhizophora mangle and Laguncularia racemosa co-occur along many intertidal floodplains in the Neotropics. Their patterns of dominance shift along various gradients, coincident with salinity, soil fertility, and tidal flooding. We used leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> metrics to investigate the strategies of these two species in mixed culture to simulate competition under different salinity concentrations and hydroperiods. Semidiurnal tidal and permanent flooding hydroperiods at two constant salinity regimes (10 g L−1 and 40 g L−1) were simulated over 10 months. Assimilation (A), stomatal conductance (gw), intercellular CO2 concentration (Ci), instantaneous photosynthetic water use efficiency (PWUE), and photosynthetic nitrogen use efficiency (PNUE) were determined at the leaf level for both species over two time periods. Rhizophora mangle had significantly higher PWUE than did L. racemosa seedlings at low salinities; however, L. racemosa had higher PNUE and stomatal conductance and gw, accordingly, had greater intercellular CO2 (calculated) during measurements. Both species maintained similar capacities for assimilation at 10 and 40 g L−1 salinity and during both permanent and tidal hydroperiod treatments. Hydroperiod alone had no detectable effect on leaf <span class="hlt">gas</span> <span class="hlt">exchange</span>. However, PWUE increased and PNUE decreased for both species at 40 g L−1 salinity compared to 10 g L−1. At 40 g L−1 salinity, PNUE was higher for L. racemosa than R. mangle with tidal flooding. These treatments indicated that salinity influences <span class="hlt">gas</span> <span class="hlt">exchange</span> efficiency, might affect how gases are apportioned intercellularly, and accentuates different strategies for distributing leaf nitrogen to photosynthesis for these two species while growing competitively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27609764','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27609764"><span>The opening-closing rhythms of the subelytral cavity associated with <span class="hlt">gas</span> <span class="hlt">exchange</span> patterns in diapausing Colorado potato beetle, Leptinotarsa decemlineata.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kuusik, Aare; Jõgar, Katrin; Metspalu, Luule; Ploomi, Angela; Merivee, Enno; Must, Anne; Williams, Ingrid H; Hiiesaar, Külli; Sibul, Ivar; Mänd, Marika</p> <p>2016-11-01</p> <p>The opening-closing rhythms of the subelytral cavity and associated <span class="hlt">gas</span> <span class="hlt">exchange</span> patterns were monitored in diapausing Leptinotarsa decemlineata beetles. Measurements were made by means of a flow-through CO 2 analyser and a coulometric respirometer. Under the elytra of these beetles there is a more or less tightly enclosed space, the subelytral cavity (SEC). When the cavity was tightly closed, air pressure inside was sub-atmospheric, as a result of oxygen uptake into the tracheae by the beetle. In about half of the beetles, regular opening-closing rhythms of the SEC were observed visually and also recorded; these beetles displayed a discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> pattern. The SEC opened at the start of the CO 2 burst and was immediately closed. On opening, a rapid passive suction inflow of atmospheric air into the SEC occurred, recorded coulometrically as a sharp upward peak. As the CO 2 burst lasted beyond the closure of the SEC, we suggest that most of the CO 2 was expelled through the mesothoracic spiracles. In the remaining beetles, the SEC was continually semi-open, and cyclic <span class="hlt">gas</span> <span class="hlt">exchange</span> was exhibited. The locking mechanisms and structures between the elytra and between the elytra and the body were examined under a stereomicroscope and by means of microphotography. We conclude that at least some of the L. decemlineata diapausing beetles were able to close their subelytral cavity tightly, and that the cavity then served as a water-saving device. © 2016. Published by The Company of Biologists Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018TCry...12.1939A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018TCry...12.1939A"><span>Mercury in the Arctic tundra snowpack: temporal and spatial concentration patterns and trace <span class="hlt">gas</span> <span class="hlt">exchanges</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Agnan, Yannick; Douglas, Thomas A.; Helmig, Detlev; Hueber, Jacques; Obrist, Daniel</p> <p>2018-06-01</p> <p>In the Arctic, the snowpack forms the major interface between atmospheric and terrestrial cycling of mercury (Hg), a global pollutant. We investigated Hg dynamics in an interior Arctic tundra snowpack in northern Alaska during two winter seasons. Using a snow tower system to monitor Hg trace <span class="hlt">gas</span> <span class="hlt">exchange</span>, we observed consistent concentration declines of gaseous elemental Hg (Hg0<span class="hlt">gas</span>) from the atmosphere to the snowpack to soils. The snowpack itself was unlikely a direct sink for atmospheric Hg0<span class="hlt">gas</span>. In addition, there was no evidence of photochemical reduction of HgII to Hg0<span class="hlt">gas</span> in the tundra snowpack, with the exception of short periods during late winter in the uppermost snow layer. The patterns in this interior Arctic snowpack thus differ substantially from observations in Arctic coastal and temperate snowpacks. We consistently measured low concentrations of both total and dissolved Hg in snowpack throughout the two seasons. Chemical tracers showed that Hg was mainly associated with local mineral dust and regional marine sea spray inputs. Mass balance calculations show that the snowpack represents a small reservoir of Hg, resulting in low inputs during snowmelt. Taken together, the results from this study suggest that interior Arctic snowpacks are negligible sources of Hg to the Arctic.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.A43H3373K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.A43H3373K"><span>Direct observations of Biogenic Volatile Organic Compound (BVOC) Air-Sea <span class="hlt">Exchange</span> in the remote North Atlantic from the High-Wind <span class="hlt">Gas-Exchange</span> Study (HiWinGS)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, M.; Yang, M. X.; Blomquist, B.; Huebert, B. J.; Bertram, T. H.</p> <p>2014-12-01</p> <p>Biogenic Volatile Organic Compounds (BVOCs) are reactive trace gases that impact both chemistry and climate by regulating oxidant loadings, determining secondary organic aerosol production rates as well as altering particle hygroscopicity. While continental BVOC <span class="hlt">exchange</span> rates are well studied, global marine flux estimates are poorly constrained. In Fall 2013, a chemical-ionization time-of-flight mass spectrometer (CI-ToF-MS) utilizing benzene cations was deployed as part of the High Wind <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Study (HiWinGs) to quantify monoterpenes, isoprene and dimethylsulfide fluxes in the remote North Atlantic. Dimethylsulfide measurements are in strong agreement with those determined by the University of Hawaii's atmospheric pressure ionization mass-spectrometer. In the remote marine boundary layer, positive monoterpene fluxes (i.e. emissions) were observed while isoprene levels rarely exceeded the detection limit.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5091920','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5091920"><span>Characterizing the drivers of seedling leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> responses to warming and altered precipitation: indirect and direct effects</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Smith, Nicholas G.; Pold, Grace; Goranson, Carol; Dukes, Jeffrey S.</p> <p>2016-01-01</p> <p>Anthropogenic forces are projected to lead to warmer temperatures and altered precipitation patterns globally. The impact of these climatic changes on the uptake of carbon by the land surface will, in part, determine the rate and magnitude of these changes. However, there is a great deal of uncertainty in how terrestrial ecosystems will respond to climate in the future. Here, we used a fully factorial warming (four levels) by precipitation (three levels) manipulation experiment in an old-field ecosystem in the northeastern USA to examine the impact of climatic changes on leaf carbon <span class="hlt">exchange</span> in five species of deciduous tree seedlings. We found that photosynthesis generally increased in response to increasing precipitation and decreased in response to warming. Respiration was less sensitive to the treatments. The net result was greater leaf carbon uptake in wetter and cooler conditions across all species. Structural equation modelling revealed the primary pathway through which climate impacted leaf carbon <span class="hlt">exchange</span>. Net photosynthesis increased with increasing stomatal conductance and photosynthetic enzyme capacity (Vcmax), and decreased with increasing respiration of leaves. Soil moisture and leaf temperature at the time of measurement most heavily influenced these primary drivers of net photosynthesis. Leaf respiration increased with increasing soil moisture, leaf temperature, and photosynthetic supply of substrates. Counter to the soil moisture response, respiration decreased with increasing precipitation amount, indicating that the response to short- (i.e. soil moisture) versus long-term (i.e. precipitation amount) water stress differed, possibly as a result of changes in the relative amounts of growth and maintenance demand for respiration over time. These data (>500 paired measurements of light and dark leaf <span class="hlt">gas</span> <span class="hlt">exchange</span>), now publicly available, detail the pathways by which climate can impact leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and could be useful for testing assumptions in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/38487','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/38487"><span>Leaf-level <span class="hlt">gas-exchange</span> uniformity and photosynthetic capacity among loblolly pine (Pinus taeda L.) genotypes of contrasting inherent genetic variation</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Michael J. Aspinwall; John S. King; Steven E. McKeand; Jean-Christophe Domec</p> <p>2011-01-01</p> <p>Variation in leaf-level <span class="hlt">gas</span> <span class="hlt">exchange</span> among widely planted genetically improved loblolly pine (Pinus taeda L.) genotypes could impact stand-level water use, carbon assimilation, biomass production, C allocation, ecosystem sustainability and biogeochemical cycling under changing environmental conditions. We examined uniformity in leaf-level light-saturated photosynthesis...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=286462','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=286462"><span>Effects of permethrin and amitraz on <span class="hlt">gas</span> <span class="hlt">exchange</span> and water loss in unfed adult females of Amblyomma americanum (Acari: Ixodidae)</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Effects of permethrin and amitraz on metabolism of the lone star tick, Amblyomma americanum, were examined using a flow-through carbon dioxide (CO2) and water vapor analyzer. Untreated adult female ticks exhibited a distinct discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> pattern (DGEP) with no measurable water loss. Si...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/37550','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/37550"><span>Do chestnut, northern red, and white oak germinant seedlings respond similary to light treatments? II. <span class="hlt">Gas</span> <span class="hlt">exchange</span> and chlorophyll responses</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Joanne Rebbeck; Amy Scherzer; Kurt Gottschalk</p> <p>2012-01-01</p> <p>Understanding differences in physiological and growth strategies in low-light environments among upland oak species may help managers address the challenges of oaks' poor regeneration. <span class="hlt">Gas</span> <span class="hlt">exchange</span> and chlorophyll content were measured for northern red oak (Quercus rubra L.), chestnut oak (Quercus prinus L.), and white oak (...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1395308','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1395308"><span>Circadian rhythms have significant effects on leaf-to-canopy scale <span class="hlt">gas</span> <span class="hlt">exchange</span> under field conditions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Resco de Dios, Víctor; Gessler, Arthur; Ferrio, Juan Pedro</p> <p></p> <p>Background Molecular clocks drive oscillations in leaf photosynthesis, stomatal conductance, and other cell and leaf-level processes over ~24 h under controlled laboratory conditions. The influence of such circadian regulation over whole-canopy fluxes remains uncertain; diurnal CO 2 and H 2O vapor flux dynamics in the field are currently interpreted as resulting almost exclusively from direct physiological responses to variations in light, temperature and other environmental factors. We tested whether circadian regulation would affect plant and canopy <span class="hlt">gas</span> <span class="hlt">exchange</span> at the Montpellier European Ecotron. Canopy and leaf-level fluxes were constantly monitored under field-like environmental conditions, and under constant environmental conditions (nomore » variation in temperature, radiation, or other environmental cues). Results We show direct experimental evidence at canopy scales of the circadian regulation of daytime <span class="hlt">gas</span> <span class="hlt">exchange</span>: 20–79 % of the daily variation range in CO 2 and H 2O fluxes occurred under circadian entrainment in canopies of an annual herb (bean) and of a perennial shrub (cotton). We also observed that considering circadian regulation improved performance by 8–17 % in commonly used stomatal conductance models. Conclusions Our results show that circadian controls affect diurnal CO 2 and H 2O flux patterns in entire canopies in field-like conditions, and its consideration significantly improves model performance. Lastly, circadian controls act as a ‘memory’ of the past conditions experienced by the plant, which synchronizes metabolism across entire plant canopies.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1395308-circadian-rhythms-have-significant-effects-leaf-canopy-scale-gas-exchange-under-field-conditions','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1395308-circadian-rhythms-have-significant-effects-leaf-canopy-scale-gas-exchange-under-field-conditions"><span>Circadian rhythms have significant effects on leaf-to-canopy scale <span class="hlt">gas</span> <span class="hlt">exchange</span> under field conditions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Resco de Dios, Víctor; Gessler, Arthur; Ferrio, Juan Pedro; ...</p> <p>2016-10-20</p> <p>Background Molecular clocks drive oscillations in leaf photosynthesis, stomatal conductance, and other cell and leaf-level processes over ~24 h under controlled laboratory conditions. The influence of such circadian regulation over whole-canopy fluxes remains uncertain; diurnal CO 2 and H 2O vapor flux dynamics in the field are currently interpreted as resulting almost exclusively from direct physiological responses to variations in light, temperature and other environmental factors. We tested whether circadian regulation would affect plant and canopy <span class="hlt">gas</span> <span class="hlt">exchange</span> at the Montpellier European Ecotron. Canopy and leaf-level fluxes were constantly monitored under field-like environmental conditions, and under constant environmental conditions (nomore » variation in temperature, radiation, or other environmental cues). Results We show direct experimental evidence at canopy scales of the circadian regulation of daytime <span class="hlt">gas</span> <span class="hlt">exchange</span>: 20–79 % of the daily variation range in CO 2 and H 2O fluxes occurred under circadian entrainment in canopies of an annual herb (bean) and of a perennial shrub (cotton). We also observed that considering circadian regulation improved performance by 8–17 % in commonly used stomatal conductance models. Conclusions Our results show that circadian controls affect diurnal CO 2 and H 2O flux patterns in entire canopies in field-like conditions, and its consideration significantly improves model performance. Lastly, circadian controls act as a ‘memory’ of the past conditions experienced by the plant, which synchronizes metabolism across entire plant canopies.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27765071','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27765071"><span>Circadian rhythms have significant effects on leaf-to-canopy scale <span class="hlt">gas</span> <span class="hlt">exchange</span> under field conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Resco de Dios, Víctor; Gessler, Arthur; Ferrio, Juan Pedro; Alday, Josu G; Bahn, Michael; Del Castillo, Jorge; Devidal, Sébastien; García-Muñoz, Sonia; Kayler, Zachary; Landais, Damien; Martín-Gómez, Paula; Milcu, Alexandru; Piel, Clément; Pirhofer-Walzl, Karin; Ravel, Olivier; Salekin, Serajis; Tissue, David T; Tjoelker, Mark G; Voltas, Jordi; Roy, Jacques</p> <p>2016-10-20</p> <p>Molecular clocks drive oscillations in leaf photosynthesis, stomatal conductance, and other cell and leaf-level processes over ~24 h under controlled laboratory conditions. The influence of such circadian regulation over whole-canopy fluxes remains uncertain; diurnal CO 2 and H 2 O vapor flux dynamics in the field are currently interpreted as resulting almost exclusively from direct physiological responses to variations in light, temperature and other environmental factors. We tested whether circadian regulation would affect plant and canopy <span class="hlt">gas</span> <span class="hlt">exchange</span> at the Montpellier European Ecotron. Canopy and leaf-level fluxes were constantly monitored under field-like environmental conditions, and under constant environmental conditions (no variation in temperature, radiation, or other environmental cues). We show direct experimental evidence at canopy scales of the circadian regulation of daytime <span class="hlt">gas</span> <span class="hlt">exchange</span>: 20-79 % of the daily variation range in CO 2 and H 2 O fluxes occurred under circadian entrainment in canopies of an annual herb (bean) and of a perennial shrub (cotton). We also observed that considering circadian regulation improved performance by 8-17 % in commonly used stomatal conductance models. Our results show that circadian controls affect diurnal CO 2 and H 2 O flux patterns in entire canopies in field-like conditions, and its consideration significantly improves model performance. Circadian controls act as a 'memory' of the past conditions experienced by the plant, which synchronizes metabolism across entire plant canopies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16246857','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16246857"><span>Water stress-induced modifications of leaf hydraulic architecture in sunflower: co-ordination with <span class="hlt">gas</span> <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nardini, Andrea; Salleo, Sebastiano</p> <p>2005-12-01</p> <p>The hydraulic architecture, water relationships, and <span class="hlt">gas</span> <span class="hlt">exchange</span> of leaves of sunflower plants, grown under different levels of water stress, were measured. Plants were either irrigated with tap water (controls) or with PEG600 solutions with osmotic potential of -0.4 and -0.8 MPa (PEG04 and PEG08 plants, respectively). Mature leaves were measured for hydraulic resistance (R(leaf)) before and after making several cuts across minor veins, thus getting the hydraulic resistance of the venation system (R(venation)). R(leaf) was nearly the same in controls and PEG04 plants but it was reduced by about 30% in PEG08 plants. On the contrary, R(venation) was lowest in controls and increased in PEG04 and PEG08 plants as a likely result of reduction in the diameter of the veins' conduits. As a consequence, the contribution of R(venation) to the overall R(leaf) markedly increased from controls to PEG08 plants. Leaf conductance to water vapour (g(L)) was highest in controls and significantly lower in PEG04 and PEG08 plants. Moreover, g(L) was correlated to R(venation) and to leaf water potential (psi(leaf)) with highly significant linear relationships. It is concluded that water stress has an important effect on the hydraulic construction of leaves. This, in turn, might prove to be a crucial factor in plant-water relationships and <span class="hlt">gas</span> <span class="hlt">exchange</span> under water stress conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23305981','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23305981"><span>Airway <span class="hlt">exchange</span> of highly soluble gases.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hlastala, Michael P; Powell, Frank L; Anderson, Joseph C</p> <p>2013-03-01</p> <p>Highly blood soluble gases <span class="hlt">exchange</span> with the bronchial circulation in the airways. On inhalation, air absorbs highly soluble gases from the airway mucosa and equilibrates with the blood before reaching the alveoli. Highly soluble <span class="hlt">gas</span> partial pressure is identical throughout all alveoli. At the end of exhalation the partial pressure of a highly soluble <span class="hlt">gas</span> decreases from the alveolar level in the terminal bronchioles to the end-exhaled partial pressure at the mouth. A mathematical model simulated the airway <span class="hlt">exchange</span> of four gases (methyl isobutyl ketone, acetone, ethanol, and propylene glycol monomethyl ether) that have high water and blood solubility. The impact of solubility on the relative distribution of airway <span class="hlt">exchange</span> was studied. We conclude that an increase in water solubility shifts the distribution of <span class="hlt">gas</span> <span class="hlt">exchange</span> toward the mouth. Of the four gases studied, ethanol had the greatest decrease in partial pressure from the alveolus to the mouth at end exhalation. Single exhalation breath tests are inappropriate for estimating alveolar levels of highly soluble gases, particularly for ethanol.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4888954','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4888954"><span>Airway <span class="hlt">exchange</span> of highly soluble gases</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Powell, Frank L.; Anderson, Joseph C.</p> <p>2013-01-01</p> <p>Highly blood soluble gases <span class="hlt">exchange</span> with the bronchial circulation in the airways. On inhalation, air absorbs highly soluble gases from the airway mucosa and equilibrates with the blood before reaching the alveoli. Highly soluble <span class="hlt">gas</span> partial pressure is identical throughout all alveoli. At the end of exhalation the partial pressure of a highly soluble <span class="hlt">gas</span> decreases from the alveolar level in the terminal bronchioles to the end-exhaled partial pressure at the mouth. A mathematical model simulated the airway <span class="hlt">exchange</span> of four gases (methyl isobutyl ketone, acetone, ethanol, and propylene glycol monomethyl ether) that have high water and blood solubility. The impact of solubility on the relative distribution of airway <span class="hlt">exchange</span> was studied. We conclude that an increase in water solubility shifts the distribution of <span class="hlt">gas</span> <span class="hlt">exchange</span> toward the mouth. Of the four gases studied, ethanol had the greatest decrease in partial pressure from the alveolus to the mouth at end exhalation. Single exhalation breath tests are inappropriate for estimating alveolar levels of highly soluble gases, particularly for ethanol. PMID:23305981</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MPLB...3250060G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MPLB...3250060G"><span>Finite-T correlations and free <span class="hlt">exchange</span>-correlation energy of quasi-one-dimensional electron <span class="hlt">gas</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Garg, Vinayak; Sharma, Akariti; Moudgil, R. K.</p> <p>2018-02-01</p> <p>We have studied the effect of temperature on static density-density correlations and plasmon excitation spectrum of quasi-one-dimensional electron <span class="hlt">gas</span> (Q1DEG) using the random phase approximation (RPA). Numerical results for static structure factor, pair-correlation function, static density susceptibility, free <span class="hlt">exchange</span>-correlation energy and plasmon dispersion are presented over a wide range of temperature and electron density. As an interesting result, we find that the short-range correlations exhibit a non-monotonic dependence on temperature T, initially growing stronger (i.e. the pair-correlation function at small inter-electron spacing assuming relatively smaller values) with increasing T and then weakening above a critical T. The cross-over temperature is found to increase with increasing coupling among electrons. Also, the q = 2kF peak in the static density susceptibility χ(q,ω = 0,T) at T = 0 K smears out with rising T. The free <span class="hlt">exchange</span>-correlation energy and plasmon dispersion show a significant variation with T, and the trend is qualitatively the same as in higher dimensions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/30356','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/30356"><span>Growth, <span class="hlt">gas</span> <span class="hlt">exchange</span>, and root respiration of Quercus rubra seedlings exposed to low root zone temperatures in solution culture</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Kent G. Apostol; Douglass F. Jacobs; Barrett C. Wilson; K. Francis Salifu; R. Kasten Dumroese</p> <p>2007-01-01</p> <p>Spring planting is standard operational practice in the Central Hardwood Region, though little is known about potential impacts of low root temperature (RT) common during spring on establishment success of temperate deciduous forest tree species. The effects of low RTon growth, <span class="hlt">gas</span> <span class="hlt">exchange</span>, and root respiration following winter dormancy were studied in 1-year-old...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26993234','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26993234"><span>A two-dimensional microscale model of <span class="hlt">gas</span> <span class="hlt">exchange</span> during photosynthesis in maize (Zea mays L.) leaves.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Retta, Moges; Ho, Quang Tri; Yin, Xinyou; Verboven, Pieter; Berghuijs, Herman N C; Struik, Paul C; Nicolaï, Bart M</p> <p>2016-05-01</p> <p>CO2 <span class="hlt">exchange</span> in leaves of maize (Zea mays L.) was examined using a microscale model of combined <span class="hlt">gas</span> diffusion and C4 photosynthesis kinetics at the leaf tissue level. Based on a generalized scheme of photosynthesis in NADP-malic enzyme type C4 plants, the model accounted for CO2 diffusion in a leaf tissue, CO2 hydration and assimilation in mesophyll cells, CO2 release from decarboxylation of C4 acids, CO2 fixation in bundle sheath cells and CO2 retro-diffusion from bundle sheath cells. The transport equations were solved over a realistic 2-D geometry of the Kranz anatomy obtained from light microscopy images. The predicted responses of photosynthesis rate to changes in ambient CO2 and irradiance compared well with those obtained from <span class="hlt">gas</span> <span class="hlt">exchange</span> measurements. A sensitivity analysis showed that the CO2 permeability of the mesophyll-bundle sheath and airspace-mesophyll interfaces strongly affected the rate of photosynthesis and bundle sheath conductance. Carbonic anhydrase influenced the rate of photosynthesis, especially at low intercellular CO2 levels. In addition, the suberin layer at the exposed surface of the bundle sheath cells was found beneficial in reducing the retro-diffusion. The model may serve as a tool to investigate CO2 diffusion further in relation to the Kranz anatomy in C4 plants. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhCS.817a2010W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhCS.817a2010W"><span>Performance of <span class="hlt">gas</span> diffusion layer from coconut waste for proton <span class="hlt">exchange</span> membrane fuel cell</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Widodo, H.; Destyorini, F.; Insiyanda, D. R.; Subhan, A.</p> <p>2017-04-01</p> <p>The performance of <span class="hlt">Gas</span> Diffusion Layer (GDL) synthesized from coconut waste. <span class="hlt">Gas</span> Diffusion Layer (GDL), produced from coconut waste, as a part of Proton <span class="hlt">Exchange</span> Membrane Fuel Cell (PEMFC) component, has been characterized. In order to know the performance, the commercial products were used as the remaining parts of PEMFC. The proposed GDL possesses 69% porosity for diffusion of Hydrogen fuel and Oxygen, as well as for transporting electron. With the electrical conductivity of 500 mS.cm-1, it also has hydrophobic properties, which is important to avoid the reaction with water, with the contact angle of 139°. The 5 × 5 cm2 GDL paper was co-assembled with the catalyst, Nafion membrane, bipolar plate, current collector, end plate to obtain single Stack PEMFC. The performance was examined by flowing fuel and <span class="hlt">gas</span> with the flow rate of 500 and 1000 ml.min-1, respectively, and analyse the I-V polarization curve. The measurements were carried out at 30, 35, and 40°C for 5 cycles to ensure the repeatability. The results shows that the current density and the maximum power density reaches 203 mA.cm-2 and 143 mW.cm-2, respectively, with a given voltage 0.6 V, at 40°C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhDT........91K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhDT........91K"><span>Protein and Peptide <span class="hlt">Gas</span>-phase Structure Investigation Using Collision Cross Section Measurements and Hydrogen Deuterium <span class="hlt">Exchange</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khakinejad, Mahdiar</p> <p></p> <p>Protein and peptide <span class="hlt">gas</span>-phase structure analysis provides the opportunity to study these species outside of their explicit environment where the interaction network with surrounding molecules makes the analysis difficult [1]. Although <span class="hlt">gas</span>-phase structure analysis offers a unique opportunity to study the intrinsic behavior of these biomolecules [2-4], proteins and peptides exhibit very low vapor pressures [2]. Peptide and protein ions can be rendered in the <span class="hlt">gas</span>-phase using electrospray ionization (ESI) [5]. There is a growing body of literature that shows proteins and peptides can maintain solution structures during the process of ESI and these structures can persist for a few hundred milliseconds [6-9]. Techniques for monitoring <span class="hlt">gas</span>-phase protein and peptide ion structures are categorized as physical probes and chemical probes. Collision cross section (CCS) measurement, being a physical probe, is a powerful method to investigate <span class="hlt">gas</span>-phase structure size [3, 7, 10-15]; however, CCS values alone do not establish a one to one relation with structure(i.e., the CCS value is an orientationally averaged value [15-18]. Here we propose the utility of <span class="hlt">gas</span>-phase hydrogen deuterium <span class="hlt">exchange</span> (HDX) as a second criterion of structure elucidation. The proposed approach incudes extensive MD simulations to sample biomolecular ion conformation space with the production of numerous, random in-silico structures. Subsequently a CCS can be calculated for these structures and theoretical CCS values are compared with experimental values to produce a pool of candidate structures. Utilizing a chemical reaction model based on the <span class="hlt">gas</span>-phase HDX mechanism, the HDX kinetics behavior of these candidate structures are predicted and compared to experimental results to nominate the best in-silico structures which match (chemically and physically) with experimental observations. For the predictive approach to succeed, an extensive technique and method development is essential. To combine CCS</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1061681','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1061681"><span>Whole Plant and Leaf Steady State <span class="hlt">Gas</span> <span class="hlt">Exchange</span> during Ethylene Exposure in Xanthium strumarium L. 1</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Woodrow, Lorna; Jiao, Jirong; Tsujita, M. James; Grodzinski, Bernard</p> <p>1989-01-01</p> <p>The effects of ethylene evolved from ethephon on leaf and whole plant photosynthesis in Xanthium strumarium L. were examined. Ethylene-induced epinasty reduced light interception by the leaves of ethephon treated plants by up to 60%. <span class="hlt">Gas</span> <span class="hlt">exchange</span> values of individual, attached leaves under identical assay conditions were not inhibited even after 36 hours of ethylene exposure, although treated leaves required a longer induction period to achieve steady state photosynthesis. The speed of translocation of recently fixed 11C-assimilate movement was not seriously impaired following ethephon treatment; however, a greater proportion of the assimilate was partitioned downward toward the roots. Within 24 hours of ethephon treatment, the whole plant net carbon <span class="hlt">exchange</span> rate expressed on a per plant basis or a leaf area basis had dropped by 35%. The apparent inhibition of net carbon <span class="hlt">exchange</span> rate was reversed by physically repositioning the leaves with respect to the light source. Ethylene exposure also inhibited expansion of young leaves which was partially reversed when the leaves were repositioned. The data indicated that ethylene indirectly affected net C gain and plant growth through modification of light interception and altered sink demand without directly inhibiting leaf photosynthesis. Images Figure 1 PMID:16666773</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23869066','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23869066"><span>Multiple inert <span class="hlt">gas</span> elimination technique by micropore membrane inlet mass spectrometry--a comparison with reference <span class="hlt">gas</span> chromatography.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kretzschmar, Moritz; Schilling, Thomas; Vogt, Andreas; Rothen, Hans Ulrich; Borges, João Batista; Hachenberg, Thomas; Larsson, Anders; Baumgardner, James E; Hedenstierna, Göran</p> <p>2013-10-15</p> <p>The mismatching of alveolar ventilation and perfusion (VA/Q) is the major determinant of impaired <span class="hlt">gas</span> <span class="hlt">exchange</span>. The gold standard for measuring VA/Q distributions is based on measurements of the elimination and retention of infused inert gases. Conventional multiple inert <span class="hlt">gas</span> elimination technique (MIGET) uses <span class="hlt">gas</span> chromatography (GC) to measure the inert <span class="hlt">gas</span> partial pressures, which requires tonometry of blood samples with a <span class="hlt">gas</span> that can then be injected into the chromatograph. The method is laborious and requires meticulous care. A new technique based on micropore membrane inlet mass spectrometry (MMIMS) facilitates the handling of blood and <span class="hlt">gas</span> samples and provides nearly real-time analysis. In this study we compared MIGET by GC and MMIMS in 10 piglets: 1) 3 with healthy lungs; 2) 4 with oleic acid injury; and 3) 3 with isolated left lower lobe ventilation. The different protocols ensured a large range of normal and <span class="hlt">abnormal</span> VA/Q distributions. Eight inert gases (SF6, krypton, ethane, cyclopropane, desflurane, enflurane, diethyl ether, and acetone) were infused; six of these gases were measured with MMIMS, and six were measured with GC. We found close agreement of retention and excretion of the gases and the constructed VA/Q distributions between GC and MMIMS, and predicted PaO2 from both methods compared well with measured PaO2. VA/Q by GC produced more widely dispersed modes than MMIMS, explained in part by differences in the algorithms used to calculate VA/Q distributions. In conclusion, MMIMS enables faster measurement of VA/Q, is less demanding than GC, and produces comparable results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/4161933-exchange-deuterium-methanol-over-raney-nickel-catalyst-effect-certain-nitro-compounds-upon-exchange','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/4161933-exchange-deuterium-methanol-over-raney-nickel-catalyst-effect-certain-nitro-compounds-upon-exchange"><span>THE <span class="hlt">EXCHANGE</span> OF DEUTERIUM WITH METHANOL OVER RANEY NICKEL CATALYST AND THE EFFECT OF CERTAIN NITRO COMPOUNDS UPON THE <span class="hlt">EXCHANGE</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Smith, H.A.; Stewart, B.B.</p> <p></p> <p>Deuterium <span class="hlt">gas</span> <span class="hlt">exchanges</span> slowly with liquid methanol over Raney nickel catalyst at 35 deg . The reaction is zero order with respect to deuterium pressure and has a low activation energy. The influences of catalyst weight, catalyst treatment, and of the presence of certain nitro compounds were studied. Since active Raney nickel can liberate hydrogen directly, a method for determining the origin of hydrogen which undergoes <span class="hlt">exchange</span> with the deuterium <span class="hlt">gas</span> was developed. It was shown that the <span class="hlt">exchanged</span> hydrogen does originate from the hydroxyl hydrogen of methanol. The results are discussed in the light of the mechanism of catalyticmore » <span class="hlt">exchange</span> and catalytic hydrogenation reactions. (auth)« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992mshe.rept.....D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992mshe.rept.....D"><span>Microtube strip heat <span class="hlt">exchanger</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Doty, F. D.</p> <p>1992-07-01</p> <p>The purpose of this contract has been to explore the limits of miniaturization of heat <span class="hlt">exchangers</span> with the goals of (1) improving the theoretical understanding of laminar heat <span class="hlt">exchangers</span>, (2) evaluating various manufacturing difficulties, and (3) identifying major applications for the technology. A low-cost, ultra-compact heat <span class="hlt">exchanger</span> could have an enormous impact on industry in the areas of cryocoolers and energy conversion. Compact cryocoolers based on the reverse Brayton cycle (RBC) would become practical with the availability of compact heat <span class="hlt">exchangers</span>. Many experts believe that hardware advances in personal computer technology will rapidly slow down in four to six years unless lowcost, portable cryocoolers suitable for the desktop supercomputer can be developed. Compact refrigeration systems would permit dramatic advances in high-performance computer work stations with 'conventional' microprocessors operating at 150 K, and especially with low-cost cryocoolers below 77 K. NASA has also expressed strong interest in our MTS <span class="hlt">exchanger</span> for space-based RBC cryocoolers for sensor cooling. We have demonstrated feasibility of higher specific conductance by a factor of five than any other work in high-temperature <span class="hlt">gas-to-gas</span> <span class="hlt">exchangers</span>. These laminar-flow, microtube <span class="hlt">exchangers</span> exhibit extremely low pressure drop compared to alternative compact designs under similar conditions because of their much shorter flow length and larger total flow area for lower flow velocities. The design appears to be amenable to mass production techniques, but considerable process development remains. The reduction in materials usage and the improved heat <span class="hlt">exchanger</span> performance promise to be of enormous significance in advanced engine designs and in cryogenics.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29303516','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29303516"><span><span class="hlt">Gas</span> phase 1H NMR studies and kinetic modeling of dihydrogen isotope equilibration catalyzed by Ru-nanoparticles under normal conditions: dissociative vs. associative <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Limbach, Hans-Heinrich; Pery, Tal; Rothermel, Niels; Chaudret, Bruno; Gutmann, Torsten; Buntkowsky, Gerd</p> <p>2018-04-25</p> <p>The equilibration of H2, HD and D2 between the <span class="hlt">gas</span> phase and surface hydrides of solid organic-ligand-stabilized Ru metal nanoparticles has been studied by <span class="hlt">gas</span> phase 1H NMR spectroscopy using closed NMR tubes as batch reactors at room temperature and 800 mbar. When two different nanoparticle systems, Ru/PVP (PVP ≡ polyvinylpyrrolidone) and Ru/HDA (HDA ≡ hexadecylamine) were exposed to D2 <span class="hlt">gas</span>, only the release of HD from the hydride containing surface could be detected in the initial stages of the reaction, but no H2. In the case of Ru/HDA also the reverse experiment was performed where surface deuterated nanoparticles were exposed to H2. In that case, the conversion of H2 into gaseous HD was detected. In order to analyze the experimental kinetic and spectroscopic data, we explored two different mechanisms taking into account potential kinetic and equilibrium H/D isotope effects. Firstly, we explored the dissociative <span class="hlt">exchange</span> mechanism consisting of dissociative adsorption of dihydrogen, fast hydride surface diffusion and associative desorption of dihydrogen. It is shown that if D2 is the reaction partner, only H2 will be released in the beginning of the reaction, and HD only in later reaction stages. The second mechanism, dubbed here associative <span class="hlt">exchange</span> consists of the binding of dihydrogen to Ru surface atoms, followed by a H-transfer to or by H-<span class="hlt">exchange</span> with an adjacent hydride site, and finally of the associative desorption of dihydrogen. In that case, in the <span class="hlt">exchange</span> with D2, only HD will be released in the beginning of the reaction. Our experimental results are not compatible with the dissociative <span class="hlt">exchange</span> but can be explained in terms of the associative <span class="hlt">exchange</span>. Whereas the former will dominate at low temperatures and pressures, the latter will prevail around room temperature and normal pressures where transition metal nanoparticles are generally used as reaction catalysts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002GMS...127..141S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002GMS...127..141S"><span>A model of air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> incorporating the physics of the turbulent boundary layer and the properties of the sea surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Soloviev, Alexander; Schluessel, Peter</p> <p></p> <p>The model presented contains interfacial, bubble-mediated, ocean mixed layer, and remote sensing components. The interfacial (direct) <span class="hlt">gas</span> transfer dominates under conditions of low and—for quite soluble gases like CO2—moderate wind speeds. Due to the similarity between the <span class="hlt">gas</span> and heat transfer, the temperature difference, ΔT, across the thermal molecular boundary layer (cool skin of the ocean) and the interfacial <span class="hlt">gas</span> transfer coefficient, Kint are presumably interrelated. A coupled parameterization for ΔT and Kint has been derived in the context of a surface renewal model [Soloviev and Schluessel, 1994]. In addition to the Schmidt, Sc, and Prandtl, Pr, numbers, the important parameters are the surface Richardson number, Rƒ0, and the Keulegan number, Ke. The more readily available cool skin data are used to determine the coefficients that enter into both parameterizations. At high wind speeds, the Ke-number dependence is further verified with the formula for transformation of the surface wind stress to form drag and white capping, which follows from the renewal model. A further extension of the renewal model includes effects of solar radiation and rainfall. The bubble-mediated component incorporates the Merlivat et al. [1993] parameterization with the empirical coefficients estimated by Asher and Wanninkhof [1998]. The oceanic mixed layer component accounts for stratification effects on the air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span>. Based on the example of <span class="hlt">Gas</span>Ex-98, we demonstrate how the results of parameterization and modeling of the air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> can be extended to the global scale, using remote sensing techniques.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27661699','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27661699"><span>Accurate <span class="hlt">Exchange</span>-Correlation Energies for the Warm Dense Electron <span class="hlt">Gas</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Malone, Fionn D; Blunt, N S; Brown, Ethan W; Lee, D K K; Spencer, J S; Foulkes, W M C; Shepherd, James J</p> <p>2016-09-09</p> <p>The density matrix quantum Monte Carlo (DMQMC) method is used to sample exact-on-average N-body density matrices for uniform electron <span class="hlt">gas</span> systems of up to 10^{124} matrix elements via a stochastic solution of the Bloch equation. The results of these calculations resolve a current debate over the accuracy of the data used to parametrize finite-temperature density functionals. <span class="hlt">Exchange</span>-correlation energies calculated using the real-space restricted path-integral formalism and the k-space configuration path-integral formalism disagree by up to ∼10% at certain reduced temperatures T/T_{F}≤0.5 and densities r_{s}≤1. Our calculations confirm the accuracy of the configuration path-integral Monte Carlo results available at high density and bridge the gap to lower densities, providing trustworthy data in the regime typical of planetary interiors and solids subject to laser irradiation. We demonstrate that the DMQMC method can calculate free energies directly and present exact free energies for T/T_{F}≥1 and r_{s}≤2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1232686','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1232686"><span>Low Cost Polymer heat <span class="hlt">Exchangers</span> for Condensing Boilers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Butcher, Thomas; Trojanowski, Rebecca; Wei, George</p> <p>2015-09-30</p> <p>Work in this project sought to develop a suitable design for a low cost, corrosion resistant heat <span class="hlt">exchanger</span> as part of a high efficiency condensing boiler. Based upon the design parameters and cost analysis several geometries and material options were explored. The project also quantified and demonstrated the durability of the selected polymer/filler composite under expected operating conditions. The core material idea included a polymer matrix with fillers for thermal conductivity improvement. While the work focused on conventional heating oil, this concept could also be applicable to natural <span class="hlt">gas</span>, low sulfur heating oil, and biodiesel- although these are considered tomore » be less challenging environments. An extruded polymer composite heat <span class="hlt">exchanger</span> was designed, built, and tested during this project, demonstrating technical feasibility of this corrosion-resistant material approach. In such flue <span class="hlt">gas</span>-to-air heat <span class="hlt">exchangers</span>, the controlling resistance to heat transfer is in the <span class="hlt">gas</span>-side convective layer and not in the tube material. For this reason, the lower thermal conductivity polymer composite heat <span class="hlt">exchanger</span> can achieve overall heat transfer performance comparable to a metal heat <span class="hlt">exchanger</span>. However, with the polymer composite, the surface temperature on the <span class="hlt">gas</span> side will be higher, leading to a lower water vapor condensation rate.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28675854','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28675854"><span>Air-sea <span class="hlt">exchange</span> and <span class="hlt">gas</span>-particle partitioning of polycyclic aromatic hydrocarbons over the northwestern Pacific Ocean: Role of East Asian continental outflow.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wu, Zilan; Lin, Tian; Li, Zhongxia; Jiang, Yuqing; Li, Yuanyuan; Yao, Xiaohong; Gao, Huiwang; Guo, Zhigang</p> <p>2017-11-01</p> <p>We measured 15 parent polycyclic aromatic hydrocarbons (PAHs) in atmosphere and water during a research cruise from the East China Sea (ECS) to the northwestern Pacific Ocean (NWP) in the spring of 2015 to investigate the occurrence, air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span>, and <span class="hlt">gas</span>-particle partitioning of PAHs with a particular focus on the influence of East Asian continental outflow. The gaseous PAH composition and identification of sources were consistent with PAHs from the upwind area, indicating that the gaseous PAHs (three-to five-ring PAHs) were influenced by upwind land pollution. In addition, air-sea <span class="hlt">exchange</span> fluxes of gaseous PAHs were estimated to be -54.2-107.4 ng m -2 d -1 , and was indicative of variations of land-based PAH inputs. The logarithmic <span class="hlt">gas</span>-particle partition coefficient (logK p ) of PAHs regressed linearly against the logarithmic subcooled liquid vapor pressure (logP L 0 ), with a slope of -0.25. This was significantly larger than the theoretical value (-1), implying disequilibrium between the gaseous and particulate PAHs over the NWP. The non-equilibrium of PAH <span class="hlt">gas</span>-particle partitioning was shielded from the volatilization of three-ring gaseous PAHs from seawater and lower soot concentrations in particular when the oceanic air masses prevailed. Modeling PAH absorption into organic matter and adsorption onto soot carbon revealed that the status of PAH <span class="hlt">gas</span>-particle partitioning deviated more from the modeling K p for oceanic air masses than those for continental air masses, which coincided with higher volatilization of three-ring PAHs and confirmed the influence of air-sea <span class="hlt">exchange</span>. Meanwhile, significant linear regressions between logK p and logK oa (logK sa ) for PAHs were observed for continental air masses, suggesting the dominant effect of East Asian continental outflow on atmospheric PAHs over the NWP during the sampling campaign. Copyright © 2017 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.5758P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.5758P"><span>The Impact of a Lower Sea Ice Extent on Arctic Greenhouse <span class="hlt">Gas</span> <span class="hlt">Exchange</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parmentier, Frans-Jan W.; Christensen, Torben R.; Lotte Sørensen, Lise; Rysgaard, Søren; McGuire, A. David; Miller, Paul A.; Walker, Donald A.</p> <p>2013-04-01</p> <p>Arctic sea ice extent hit a new record low in September 2012, when it fell to a level about two times lower than the 1979-2000 average. Record low sea ice extents such as these are often hailed as an obvious example of the impact of climate change on the Arctic. Less obvious, however, are the further implications of a lower sea ice extent on Arctic greenhouse <span class="hlt">gas</span> <span class="hlt">exchange</span>. For example, a reduction in sea ice, in consort with a lower snow cover, has been connected to higher surface temperatures in the terrestrial part of the Arctic (Screen et al., 2012). These higher temperatures and longer growing seasons have the potential to alter the CO2 balance of Arctic tundra through enhanced photosynthesis and respiration, as well as the magnitude of methane emissions. In fact, large changes are already observed in terrestrial ecosystems (Post et al., 2009), and concerns have been raised of large releases of carbon through permafrost thaw (Schuur et al., 2011). While these changes in the greenhouse <span class="hlt">gas</span> balance of the terrestrial Arctic are described in numerous studies, a connection with a decline in sea ice extent is nonetheless seldom made. In addition to these changes on land, a lower sea ice extent also has a direct effect on the <span class="hlt">exchange</span> of greenhouse gases between the ocean and the atmosphere. For example, due to sea ice retreat, more ocean surface remains in contact with the atmosphere, and this has been suggested to increase the oceanic uptake of CO2 (Bates et al., 2006). However, the sustainability of this increased uptake is uncertain (Cai et al., 2010), and carbon fluxes related directly to the sea ice itself add much uncertainty to the oceanic uptake of CO2 (Nomura et al., 2006; Rysgaard et al., 2007). Furthermore, significant emissions of methane from the Arctic Ocean have been observed (Kort et al., 2012; Shakhova et al., 2010), but the consequence of a lower sea ice extent thereon is still unclear. Overall, the decline in sea ice that has been seen in recent</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38.3380B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38.3380B"><span>Mathematical modeling of the "plant community -soil-like substrate -<span class="hlt">gas</span> <span class="hlt">exchange</span> with the human" closed ecosystem</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barkhatov, Yuri; Gubanov, Vladimir; Tikhomirov, Alexander A.; Degermendzhy, Andrey G.</p> <p></p> <p>A mathematical model of the "plant community -soil-like substrate -<span class="hlt">gas</span> <span class="hlt">exchange</span> with the human" experimental biological life support system (BLSS) has been constructed to predict its functioning and estimate feasibility of controlling it. The mathematical model consists of three compartments -two `phytotron' models (with wheat and radish) and the `mycotron' model (for mushrooms). The following components are included in the model: edible mushrooms (mushroom fruit bodies and mycelium); wheat; radish; straw (processed by mycelium); dead organic matter in the phytotron (separately for the wheat unit and for the radish unit); worms; worms' coprolites; vermicompost used as a soil-like substrate (SLS); bacterial microflora; min-eral nitrogen, phosphorus and iron; products of the system intended for humans (wheat grains, radish roots and mushroom fruit bodies); oxygen and carbon dioxide. Under continuous <span class="hlt">gas</span> <span class="hlt">exchange</span>, the mass <span class="hlt">exchange</span> between the compartments occurs at the harvesting time. The conveyor character of the closed ecosystem functioning has been taken into account -the num-ber of culture age groups can be regulated (in experiments -4 and 8 age groups). The conveyor cycle duration can be regulated as well. The module is designed for the food and <span class="hlt">gas</span> <span class="hlt">exchange</span> requirements of 1/30 of a virtually present human. Aim of model analysis is determination of investigation direction in real experimental BLSS. The model allows doing dynamic calcu-lations of closure coefficient based on the main elements taken into account in the model and evaluating all dynamic components of the system under different conditions and modes of its operation, especially under the conditions that can hardly be created experimentally. One of the sustainability conditions can be long-duration functioning of the system under the light-ing that is far from the optimum. The mathematical model of the system can demonstrate variants of its sustainable functioning or ruin under various critical</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MS%26E..101a2090K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MS%26E..101a2090K"><span>Optimization of UA of heat <span class="hlt">exchangers</span> and BOG compressor exit pressure of LNG boil-off <span class="hlt">gas</span> reliquefaction system using exergy analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kochunni, Sarun Kumar; Ghosh, Parthasarathi; Chowdhury, Kanchan</p> <p>2015-12-01</p> <p>Boil-off <span class="hlt">gas</span> (BOG) generation and its handling are important issues in Liquefied natural <span class="hlt">gas</span> (LNG) value chain because of economic, environment and safety reasons. Several variants of reliquefaction systems of BOG have been proposed by researchers. Thermodynamic analyses help to configure them and size their components for improving performance. In this paper, exergy analysis of reliquefaction system based on nitrogen-driven reverse Brayton cycle is carried out through simulation using Aspen Hysys 8.6®, a process simulator and the effects of heat <span class="hlt">exchanger</span> size with and without related pressure drop and BOG compressor exit pressure are evaluated. Nondimensionalization of parameters with respect to the BOG load allows one to scale up or down the design. The process heat <span class="hlt">exchanger</span> (PHX) requires much higher surface area than that of BOG condenser and it helps to reduce the quantity of methane vented out to atmosphere. As pressure drop destroys exergy, optimum UA of PHX decreases for highest system performance if pressure drop is taken into account. Again, for fixed sizes of heat <span class="hlt">exchangers</span>, as there is a range of discharge pressures of BOG compressor at which the loss of methane in vent minimizes, the designer should consider choosing the pressure at lower value.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/5394062-isotopic-exchange-during-derivatization-platelet-activating-factor-gas-chromatography-mass-spectrometry','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5394062-isotopic-exchange-during-derivatization-platelet-activating-factor-gas-chromatography-mass-spectrometry"><span>Isotopic <span class="hlt">exchange</span> during derivatization of platelet activating factor for <span class="hlt">gas</span> chromatography-mass spectrometry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Haroldsen, P.E.; Gaskell, S.J.; Weintraub, S.T.</p> <p>1991-04-01</p> <p>One approach to the quantitative analysis of platelet activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycerol-3-phosphocholine; also referred to as AGEPC, alkyl glyceryl ether phosphocholine) is hydrolytic removal of the phosphocholine group and conversion to an electron-capturing derivative for <span class="hlt">gas</span> chromatography-negative ion mass spectrometry. (2H3)Acetyl-AGEPC has been commonly employed as an internal standard. When 1-hexadecyl-2-(2H3)acetyl glycerol (obtained by enzymatic hydrolysis of (2H3)-C16:0 AGEPC) is treated with pentafluorobenzoyl chloride at 120 degrees C, the resulting 3-pentafluorobenzoate derivative shows extensive loss of the deuterium label. This <span class="hlt">exchange</span> is evidently acid-catalyzed since derivatization of 1-hexadecyl-2-acetyl glycerol under the same conditions in the presence of a trace ofmore » 2HCl results in the incorporation of up to three deuterium atoms. Isotope <span class="hlt">exchange</span> can be avoided if the reaction is carried out at low temperature in the presence of base. Direct derivatization of (2H3)-C16:0 AGEPC by treatment with pentafluorobenzoyl chloride or heptafluorobutyric anhydride also results in loss of the deuterium label. The use of (13C2)-C16:0 AGEPC as an internal standard is recommended for rigorous quantitative analysis.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhCS.891a2002S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhCS.891a2002S"><span>A study of external heat <span class="hlt">exchange</span> between the vibrofluidized bed surface and the coolant <span class="hlt">gas</span> in devices used for spent nuclear fuel regeneration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sapozhnikov, B. G.; Gorbunova, A. M.; Zelenkova, Yu O.; Shiriaeva, N. P.</p> <p>2017-10-01</p> <p>The oxidative recrystallization of spent nuclear fuel running in the vibrofluidized bed mode requires a continuous supply or removal of heat, which can be performed using various techniques. The most advantageous of these is supplying a coolant <span class="hlt">gas</span> over the surface of the vibrofluidized bed. However, the available information about such heat <span class="hlt">exchange</span> processes is limited. External heat <span class="hlt">exchange</span> between the surface of the vibrofluidized bed and the blown coolant <span class="hlt">gas</span> was investigated using fuel simulators, which construction was based on narrow-fraction electrocorundum exhibiting the particle size of dP = 0,07 ÷ 1,25 mm in a device with the diameter of 100 mm and the height of 160 mm according to a stationary technique. The data on the influence of the coolant flow, the amplitude and frequency of vibration, as well as the particle size of the dispersed material were obtained. In order to explain the results obtained, we used data on the pulsations of the <span class="hlt">gas</span> flow velocities occurring in the vibrofluidized bed and depending on the parameters listed above.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2409043','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2409043"><span>Three-Dimensional <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Pathways in Pome Fruit Characterized by Synchrotron X-Ray Computed Tomography1[C][W][OA</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Verboven, Pieter; Kerckhofs, Greet; Mebatsion, Hibru Kelemu; Ho, Quang Tri; Temst, Kristiaan; Wevers, Martine; Cloetens, Peter; Nicolaï, Bart M.</p> <p>2008-01-01</p> <p>Our understanding of the <span class="hlt">gas</span> <span class="hlt">exchange</span> mechanisms in plant organs critically depends on insights in the three-dimensional (3-D) structural arrangement of cells and voids. Using synchrotron radiation x-ray tomography, we obtained for the first time high-contrast 3-D absorption images of in vivo fruit tissues of high moisture content at 1.4-μm resolution and 3-D phase contrast images of cell assemblies at a resolution as low as 0.7 μm, enabling visualization of individual cell morphology, cell walls, and entire void networks that were previously unknown. Intercellular spaces were always clear of water. The apple (Malus domestica) cortex contains considerably larger parenchyma cells and voids than pear (Pyrus communis) parenchyma. Voids in apple often are larger than the surrounding cells and some cells are not connected to void spaces. The main voids in apple stretch hundreds of micrometers but are disconnected. Voids in pear cortex tissue are always smaller than parenchyma cells, but each cell is surrounded by a tight and continuous network of voids, except near brachyssclereid groups. Vascular and dermal tissues were also measured. The visualized network architecture was consistent over different picking dates and shelf life. The differences in void fraction (5.1% for pear cortex and 23.0% for apple cortex) and in <span class="hlt">gas</span> network architecture helps explain the ability of tissues to facilitate or impede <span class="hlt">gas</span> <span class="hlt">exchange</span>. Structural changes and anisotropy of tissues may eventually lead to physiological disorders. A combined tomography and internal <span class="hlt">gas</span> analysis during growth are needed to make progress on the understanding of void formation in fruit. PMID:18417636</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/866757','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/866757"><span>Heat <span class="hlt">exchanger</span> for fuel cell power plant reformer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Misage, Robert; Scheffler, Glenn W.; Setzer, Herbert J.; Margiott, Paul R.; Parenti, Jr., Edmund K.</p> <p>1988-01-01</p> <p>A heat <span class="hlt">exchanger</span> uses the heat from processed fuel <span class="hlt">gas</span> from a reformer for a fuel cell to superheat steam, to preheat raw fuel prior to entering the reformer and to heat a water-steam coolant mixture from the fuel cells. The processed fuel <span class="hlt">gas</span> temperature is thus lowered to a level useful in the fuel cell reaction. The four temperature adjustments are accomplished in a single heat <span class="hlt">exchanger</span> with only three heat transfer cores. The heat <span class="hlt">exchanger</span> is preheated by circulating coolant and purge steam from the power section during startup of the latter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/50416','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/50416"><span>Drought limitations to leaf-level <span class="hlt">gas</span> <span class="hlt">exchange</span>: results from a model linking stomatal optimization and cohesion-tension theory</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Kimberly A. Novick; Chelcy F. Miniat; James M. Vose</p> <p>2016-01-01</p> <p>We merge concepts from stomatal optimization theory and cohesion–tension theory to examine the dynamics of three mechanisms that are potentially limiting to leaf-level <span class="hlt">gas</span> <span class="hlt">exchange</span> in trees during drought: (1) a ‘demand limitation’ driven by an assumption of optimal stomatal functioning; (2) ‘hydraulic limitation’ of water movement from the roots to the leaves...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25399878','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25399878"><span>Estimation of bias with the single-zone assumption in measurement of residential air <span class="hlt">exchange</span> using the perfluorocarbon tracer <span class="hlt">gas</span> method.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Van Ryswyk, K; Wallace, L; Fugler, D; MacNeill, M; Héroux, M È; Gibson, M D; Guernsey, J R; Kindzierski, W; Wheeler, A J</p> <p>2015-12-01</p> <p>Residential air <span class="hlt">exchange</span> rates (AERs) are vital in understanding the temporal and spatial drivers of indoor air quality (IAQ). Several methods to quantify AERs have been used in IAQ research, often with the assumption that the home is a single, well-mixed air zone. Since 2005, Health Canada has conducted IAQ studies across Canada in which AERs were measured using the perfluorocarbon tracer (PFT) <span class="hlt">gas</span> method. Emitters and detectors of a single PFT <span class="hlt">gas</span> were placed on the main floor to estimate a single-zone AER (AER(1z)). In three of these studies, a second set of emitters and detectors were deployed in the basement or second floor in approximately 10% of homes for a two-zone AER estimate (AER(2z)). In total, 287 daily pairs of AER(2z) and AER(1z) estimates were made from 35 homes across three cities. In 87% of the cases, AER(2z) was higher than AER(1z). Overall, the AER(1z) estimates underestimated AER(2z) by approximately 16% (IQR: 5-32%). This underestimate occurred in all cities and seasons and varied in magnitude seasonally, between homes, and daily, indicating that when measuring residential air <span class="hlt">exchange</span> using a single PFT <span class="hlt">gas</span>, the assumption of a single well-mixed air zone very likely results in an under prediction of the AER. The results of this study suggest that the long-standing assumption that a home represents a single well-mixed air zone may result in a substantial negative bias in air <span class="hlt">exchange</span> estimates. Indoor air quality professionals should take this finding into consideration when developing study designs or making decisions related to the recommendation and installation of residential ventilation systems. © 2014 Her Majesty the Queen in Right of Canada. Indoor Air published by John Wiley & Sons Ltd Reproduced with the permission of the Minister of Health Canada.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6110864-gas-exchange-characteristics-pinus-edulis-juniperus-monosperma','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6110864-gas-exchange-characteristics-pinus-edulis-juniperus-monosperma"><span><span class="hlt">Gas</span> <span class="hlt">exchange</span> characteristics of Pinus edulis and Juniperus monosperma</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Barnes, F.J.</p> <p>1987-07-01</p> <p>A shift in the relative dominance of Pinus edulis and Juniperus monosperma is associated with a complex elevational gradient in northern new Mexico. The ecophysiological parameters contributing to this dominance pattern were studied by determining the <span class="hlt">gas</span> <span class="hlt">exchange</span> characteristics of the two species in response to temperature, light and water stress under controlled conditions. P. edulis has a higher photosynthetic capacity than J. monosperma, and has a tendency to form ecotypes with individuals from mesic sites having higher rates of carbon gain than xeric site individuals. J. monosperma is more drought-tolerant than P. edulis. As soil moisture decreases, zero carbonmore » gain in J. monosperma occurs at a lower predawn leaf water potential (-4.6 MPa) than in P. edulis (-2.2 MPa). There is no significant difference between species in the temperature of peak carbon gain. J. monosperma has a significantly wider temperature optimum than P. edulis with the additional range being at high temperatures. The observed lower elevational limit of P. edulis coincides with its physiological tolerance of water stress as estimated by seasonal leaf carbon gain. Environmental limitations to the distribution of J. monosperma were not found at higher elevations where P. edulis is dominant.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1175556','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1175556"><span>Co-flow anode/cathode supply heat <span class="hlt">exchanger</span> for a solid-oxide fuel cell assembly</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Haltiner, Jr., Karl J.; Kelly, Sean M.</p> <p>2005-11-22</p> <p>In a solid-oxide fuel cell assembly, a co-flow heat <span class="hlt">exchanger</span> is provided in the flow paths of the reformate <span class="hlt">gas</span> and the cathode air ahead of the fuel cell stack, the reformate <span class="hlt">gas</span> being on one side of the <span class="hlt">exchanger</span> and the cathode air being on the other. The reformate <span class="hlt">gas</span> is at a substantially higher temperature than is desired in the stack, and the cathode <span class="hlt">gas</span> is substantially cooler than desired. In the co-flow heat <span class="hlt">exchanger</span>, the temperatures of the reformate and cathode streams converge to nearly the same temperature at the outlet of the <span class="hlt">exchanger</span>. Preferably, the heat <span class="hlt">exchanger</span> is formed within an integrated component manifold (ICM) for a solid-oxide fuel cell assembly.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23929076','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23929076"><span>[Vitrectomy and <span class="hlt">gas</span>-fluid <span class="hlt">exchange</span> for the treatment of serous macular detachment due to optic disc pit: long-term evaluation].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Moreira Neto, Carlos Augusto; Moreira Junior, Carlos Augusto</p> <p>2013-01-01</p> <p>To evaluate 5 patients with serous macular detachment due to optic disc pit that were submitted to pars plana vitrectomy and were followed for at least 7 years. Patients were submitted to pars plana vitrectomy, posterior hyaloid removal, autologous serum injection and <span class="hlt">gas</span>-fluid <span class="hlt">exchange</span>, without laser photocoagulation, and were evaluated pre and post-operatively with visual acuity and Amsler grid testing, retinography, and recently, with autofluorescence imaging and high resolution OCT. All 5 eyes improved visual acuity significantly following the surgical procedure maintaining good vision throughout the follow-up period. Mean pre-operative visual acuity was 20/400 and final visual acuity was 20/27 with a mean follow-up time of 13.6 years. No recurrences of serous detachments were observed. OCT examinations demonstrated an attached retina up to the margin of the pit. Serous macular detachments due to optic disc pits were adequately treated with pars plana vitrectomy and <span class="hlt">gas</span> fluid <span class="hlt">exchange</span>, without the need for laser photocoagulation, maintaining excellent visual results for a long period of time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110000601','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110000601"><span>Air Circulation and Heat <span class="hlt">Exchange</span> Under Reduced Pressures</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rygalov, V.; Wheeler, R.; Dixon, M.; Fowler, P.; Hillhouse, L.</p> <p>2010-01-01</p> <p>Heat <span class="hlt">exchange</span> rates decrease non-linearly with reductions in atmospheric pressure. This decrease creates risk of thermal stress (elevated leaf temperatures) for plants under reduced pressures. Forced convection (fans) significantly increases heat <span class="hlt">exchange</span> rate under almost all pressures except below 10 kPa. Plant cultivation techniques under reduced pressures will require forced convection. The cooling curve technique is a reliable means of assessing the influence of environmental variables like pressure and gravity on <span class="hlt">gas</span> <span class="hlt">exchange</span> of plant. These results represent the extremes of <span class="hlt">gas</span> <span class="hlt">exchange</span> conditions for simple systems under variable pressures. In reality, dense plant canopies will exhibit responses in between these extremes. More research is needed to understand the dependence of forced convection on atmospheric pressure. The overall thermal balance model should include latent and radiative <span class="hlt">exchange</span> components.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOS.A24C2606P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOS.A24C2606P"><span>Surfactant control of air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> from North Sea coastal waters and the Atlantic Meridional Transect</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pereira, R.</p> <p>2016-02-01</p> <p>Suppression of <span class="hlt">gas</span> transfer velocity (kw) by surfactants are well established, both in laboratory wind flumes and purposeful oceanic releases. However, the effects on kw of time and space varying concentrations of natural surfactant are inadequately studied. We have developed an automated <span class="hlt">gas</span> <span class="hlt">exchange</span> tank for simultaneous high precision measurement of kw in unmodified seawater samples. Here we present data from two studies along a coastal North Sea transect during 2012-2013 and the Atlantic Meridional Transect (AMT) 24 from September to November 2014. Measurements of surfactant activity (SA), CDOM absorbance and chlorophyll-a have enabled us to characterize the effects of variable amounts of natural surfactant on kw. North Sea coastal waters range in k660 (kw normalized to the value for CO2 in freshwater at 20oC) was 6.8-24.5 cm hr-1 (n=20), with the ranges of SA, total CDOM absorbance (200-450 nm) and chlorophyll-a measured in the surface microlayer (SML) of our seawater samples were 0.08-0.38 mg l-1 T-X-100, 0.13-4.7 and 0.09-1.54 µg l-1, respectively. The AMT k660 ranged from 7.0-23.9 cm hr-1 (n=22), with SA measured in the SML and subsurface water (SSW) of our seawater samples ranging from 0.15-1.08 mg l-1 T-X-100 and 0.07-0.43 mg l-1 T-X-100, respectively. Importantly, we found 12-45% (North Sea) and 1-43% (AMT) k660 suppression relative to Milli-Q water that relate to seasonal and spatial differences in SA. The North Sea demonstrated notable seasonal influences on k660 suppression that were related to CDOM absorbance and chlorophyll-a. The degree of k660 suppression was highest in summer consistent with k660 control by natural surfactant. The degree of k660 suppression decreased with distance offshore in the North Sea and displayed a strong relationship with SA (r2 = 0.51-0.64, p = 0.02, n = 20). The AMT demonstrated notable differences in k660 suppression between hemispheres and across the Longhurst Provinces but the overall relationship between k660</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10642938','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10642938"><span>Partial liquid ventilation with perfluorocarbon improves <span class="hlt">gas</span> <span class="hlt">exchange</span> and decreases inflammatory response in oleic acid-induced lung injury in beagles.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Suh, G Y; Chung, M P; Park, S J; Park, J W; Kim, H C; Kim, H; Han, J; Rhee, C H; Kwon, O J</p> <p>1999-12-01</p> <p>The aim of this study was to determine the effect of partial liquid ventilation (PLV) using a perfluorocarbon (PFC) on <span class="hlt">gas</span> <span class="hlt">exchange</span> and lung inflammatory response in a canine acute lung injury model. After inducing severe lung injury by oleic acid infusion, beagle dogs were randomized to receive either <span class="hlt">gas</span> ventilation only (control group, n = 6) or PLV (PLV group, n = 7) by sequential instillation of 10 mL/kg of perfluorodecalin (PFC) at 30 min intervals till functional residual capacity was attained. Measurements were made every 30 min till 210 min. Then the lungs were removed and bronchoalveolar lavage (BAL) (35 mL/kg) was performed on the right lung and the left lung was submitted for histologic analysis. There was significant improvement in PaO2 and PaCO2 in the PLV group compared to the control group (p < 0.05) which was associated with a significant decrease in shunt (p < 0.05). There was no significant difference in parameters of lung mechanics and hemodynamics. There was a significant decrease in cell count and neutrophil percentage in BAL fluid and significantly less inflammation and exudate scores in histology in the PLV group (p < 0.05). We conclude that PLV with perfluorodecalin improves <span class="hlt">gas</span> <span class="hlt">exchange</span> and decreases inflammatory response in the acutely-injured lung.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4674977','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4674977"><span>Estimation of bias with the single-zone assumption in measurement of residential air <span class="hlt">exchange</span> using the perfluorocarbon tracer <span class="hlt">gas</span> method</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Van Ryswyk, K; Wallace, L; Fugler, D; MacNeill, M; Héroux, M È; Gibson, M D; Guernsey, J R; Kindzierski, W; Wheeler, A J</p> <p>2015-01-01</p> <p>Residential air <span class="hlt">exchange</span> rates (AERs) are vital in understanding the temporal and spatial drivers of indoor air quality (IAQ). Several methods to quantify AERs have been used in IAQ research, often with the assumption that the home is a single, well-mixed air zone. Since 2005, Health Canada has conducted IAQ studies across Canada in which AERs were measured using the perfluorocarbon tracer (PFT) <span class="hlt">gas</span> method. Emitters and detectors of a single PFT <span class="hlt">gas</span> were placed on the main floor to estimate a single-zone AER (AER1z). In three of these studies, a second set of emitters and detectors were deployed in the basement or second floor in approximately 10% of homes for a two-zone AER estimate (AER2z). In total, 287 daily pairs of AER2z and AER1z estimates were made from 35 homes across three cities. In 87% of the cases, AER2z was higher than AER1z. Overall, the AER1z estimates underestimated AER2z by approximately 16% (IQR: 5–32%). This underestimate occurred in all cities and seasons and varied in magnitude seasonally, between homes, and daily, indicating that when measuring residential air <span class="hlt">exchange</span> using a single PFT <span class="hlt">gas</span>, the assumption of a single well-mixed air zone very likely results in an under prediction of the AER. PMID:25399878</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhRvA..97e2707F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhRvA..97e2707F"><span><span class="hlt">Exchange</span> and correlation in positronium-molecule scattering</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fabrikant, I. I.; Wilde, R. S.</p> <p>2018-05-01</p> <p><span class="hlt">Exchange</span> and correlations play a particularly important role in positronium (Ps) collisions with atoms and molecules, since the static potential for Ps interaction with a neutral system is zero. Theoretical description of both effects is a very challenging task. In the present work we use the free-electron-<span class="hlt">gas</span> model to describe <span class="hlt">exchange</span> and correlations in Ps collisions with molecules similar to the approach widely used in the theory of electron-molecule collisions. The results for <span class="hlt">exchange</span> and correlation energies are presented as functions of the Fermi momentum of the electron <span class="hlt">gas</span> and the Ps incident energy. Using the Thomas-Fermi model, these functions can be converted into <span class="hlt">exchange</span> and correlation potentials for Ps interaction with molecules as functions of the distance between the projectile and the target.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27658816','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27658816"><span>Characterizing the drivers of seedling leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> responses to warming and altered precipitation: indirect and direct effects.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Smith, Nicholas G; Pold, Grace; Goranson, Carol; Dukes, Jeffrey S</p> <p>2016-01-01</p> <p>Anthropogenic forces are projected to lead to warmer temperatures and altered precipitation patterns globally. The impact of these climatic changes on the uptake of carbon by the land surface will, in part, determine the rate and magnitude of these changes. However, there is a great deal of uncertainty in how terrestrial ecosystems will respond to climate in the future. Here, we used a fully factorial warming (four levels) by precipitation (three levels) manipulation experiment in an old-field ecosystem in the northeastern USA to examine the impact of climatic changes on leaf carbon <span class="hlt">exchange</span> in five species of deciduous tree seedlings. We found that photosynthesis generally increased in response to increasing precipitation and decreased in response to warming. Respiration was less sensitive to the treatments. The net result was greater leaf carbon uptake in wetter and cooler conditions across all species. Structural equation modelling revealed the primary pathway through which climate impacted leaf carbon <span class="hlt">exchange</span>. Net photosynthesis increased with increasing stomatal conductance and photosynthetic enzyme capacity (V cmax ), and decreased with increasing respiration of leaves. Soil moisture and leaf temperature at the time of measurement most heavily influenced these primary drivers of net photosynthesis. Leaf respiration increased with increasing soil moisture, leaf temperature, and photosynthetic supply of substrates. Counter to the soil moisture response, respiration decreased with increasing precipitation amount, indicating that the response to short- (i.e. soil moisture) versus long-term (i.e. precipitation amount) water stress differed, possibly as a result of changes in the relative amounts of growth and maintenance demand for respiration over time. These data (>500 paired measurements of light and dark leaf <span class="hlt">gas</span> <span class="hlt">exchange</span>), now publicly available, detail the pathways by which climate can impact leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and could be useful for testing assumptions in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/915245','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/915245"><span>Heat and mass <span class="hlt">exchanger</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Lowenstein, Andrew; Sibilia, Marc J.; Miller, Jeffrey A.; Tonon, Thomas</p> <p>2007-09-18</p> <p>A mass and heat <span class="hlt">exchanger</span> includes at least one first substrate with a surface for supporting a continuous flow of a liquid thereon that either absorbs, desorbs, evaporates or condenses one or more gaseous species from or to a surrounding <span class="hlt">gas</span>; and at least one second substrate operatively associated with the first substrate. The second substrate includes a surface for supporting the continuous flow of the liquid thereon and is adapted to carry a heat <span class="hlt">exchange</span> fluid therethrough, wherein heat transfer occurs between the liquid and the heat <span class="hlt">exchange</span> fluid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1018726','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1018726"><span>Heat and mass <span class="hlt">exchanger</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Lowenstein, Andrew [Princeton, NJ; Sibilia, Marc J [Princeton, NJ; Miller, Jeffrey A [Hopewell, NJ; Tonon, Thomas [Princeton, NJ</p> <p>2011-06-28</p> <p>A mass and heat <span class="hlt">exchanger</span> includes at least one first substrate with a surface for supporting a continuous flow of a liquid thereon that either absorbs, desorbs, evaporates or condenses one or more gaseous species from or to a surrounding <span class="hlt">gas</span>; and at least one second substrate operatively associated with the first substrate. The second substrate includes a surface for supporting the continuous flow of the liquid thereon and is adapted to carry a heat <span class="hlt">exchange</span> fluid therethrough, wherein heat transfer occurs between the liquid and the heat <span class="hlt">exchange</span> fluid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18848466','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18848466"><span>Probing peptide fragment ion structures by combining sustained off-resonance collision-induced dissociation and <span class="hlt">gas</span>-phase H/D <span class="hlt">exchange</span> (SORI-HDX) in Fourier transform ion-cyclotron resonance (FT-ICR) instruments.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Somogyi, Arpád</p> <p>2008-12-01</p> <p>The usefulness of <span class="hlt">gas</span>-phase H/D <span class="hlt">exchange</span> is demonstrated to probe heterogeneous fragment and parent ion populations. Singly and multiply protonated peptides/proteins were fragmented by using sustained off-resonance irradiation collision-induced dissociation (SORI-CID). The fragments and the surviving precursor ions then all undergo H/D <span class="hlt">exchange</span> in the <span class="hlt">gas</span>-phase with either D(2)O or CD(3)OD under the same experimental conditions. Usually, 10 to 60 s of reaction time is adequate to monitor characteristic differences in the H/D <span class="hlt">exchange</span> kinetic rates. These differences are then correlated to isomeric ion structures. The SORI-HDX method can be used to rapidly test fragment ion structures and provides useful insights into peptide fragmentation mechanisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27035217','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27035217"><span>Selective <span class="hlt">Gas</span> Capture Ability of <span class="hlt">Gas</span>-Adsorbent-Incorporated Cellulose Nanofiber Films.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shah, Kinjal J; Imae, Toyoko</p> <p>2016-05-09</p> <p>The 2,2,6,6-tetramethylpiperidine-1-oxyl radical-oxidized cellulose nanofibers (TOCNF) were hybridized with cation and anion-<span class="hlt">exchange</span> organoclays, where poly(amido amine) dendrimers were loaded to enhance the functionality of <span class="hlt">gas</span> adsorption, since dendrimers have the high adsorbability and the enough selectivity on the <span class="hlt">gas</span> adsorption. The thin films were prepared from the organoclay-TOCNF hybrids and supplied to the <span class="hlt">gas</span> adsorption. The adsorption of CO2 and NH3 gases increased with an increasing amount of organoclays in TOCNF films, but the behavior of the increase depended on gases, clays, and dendrimers. The hydrotalcite organoclay-TOCNF films displayed the highest adsorption of both gases, but the desorption of CO2 <span class="hlt">gas</span> from hydrotalcite organoclay-TOCNF films was drastically high in comparison with the other systems. While the CO2 <span class="hlt">gas</span> is adsorbed and remained on cationic dendrimer sites in cation-<span class="hlt">exchange</span> organoclay-TOCNF films, the CO2 <span class="hlt">gas</span> is adsorbed on cationic clay sites in anion <span class="hlt">exchange</span> organoclay-TOCNF films, and it is easily desorbed from the films. The NH3 adsorption is inversive to the CO2 adsorption. Then the CO2 molecules adsorbed on the cationic dendrimers and the NH3 molecules adsorbed on the anionic dendrimers are preferably captured in these adsorbents. The present research incorporated dendrimers will be contributing to the development of <span class="hlt">gas</span>-specialized adsorbents, which are selectively storable only in particular gases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870034957&hterms=humidification&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dhumidification','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870034957&hterms=humidification&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dhumidification"><span>Injection of dust into the Martian atmosphere - Evidence from the Viking <span class="hlt">Gas</span> <span class="hlt">Exchange</span> experiment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Huguenin, R. L.; Harris, S. L.; Carter, R.</p> <p>1986-01-01</p> <p>The hypothesis that predawn midlatitude storms are triggered by a soil humidification process is examined. A freeze/thaw model of the process is evaluated in the Viking <span class="hlt">Gas</span> <span class="hlt">Exchange</span> experiments conducted on Mars. The humidification-driven desorption and desiccation state of Martian soil samples are analyzed. The periodic humidification of equatorial regolith soil is studied in terms of pore space pressure during desorption events and soil diffusivity; the thermal properties of the regolith surface layer are modeled using the program of Clifford (1984). Consideration is given to the diurnal and seasonal cycles of the humidification process, the permanent, low-albedo features in the midlatitudes, and the production of H2SO4 and HCl aerosols.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=methane&id=EJ1084322','ERIC'); return false;" href="https://eric.ed.gov/?q=methane&id=EJ1084322"><span>Heterogeneous Catalysis: Deuterium <span class="hlt">Exchange</span> Reactions of Hydrogen and Methane</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Mirich, Anne; Miller, Trisha Hoette; Klotz, Elsbeth; Mattson, Bruce</p> <p>2015-01-01</p> <p>Two <span class="hlt">gas</span> phase deuterium/hydrogen <span class="hlt">exchange</span> reactions are described utilizing a simple inexpensive glass catalyst tube containing 0.5% Pd on alumina through which <span class="hlt">gas</span> mixtures can be passed and products collected for analysis. The first of these <span class="hlt">exchange</span> reactions involves H[subscript 2] + D[subscript 2], which proceeds at temperatures as low as 77…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/865633','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/865633"><span>Low <span class="hlt">exchange</span> element for nuclear reactor</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Brogli, Rudolf H.; Shamasunder, Bangalore I.; Seth, Shivaji S.</p> <p>1985-01-01</p> <p>A flow <span class="hlt">exchange</span> element is presented which lowers temperature gradients in fuel elements and reduces maximum local temperature within high temperature <span class="hlt">gas</span>-cooled reactors. The flow <span class="hlt">exchange</span> element is inserted within a column of fuel elements where it serves to redirect coolant flow. Coolant which has been flowing in a hotter region of the column is redirected to a cooler region, and coolant which has been flowing in the cooler region of the column is redirected to the hotter region. The safety, efficiency, and longevity of the high temperature <span class="hlt">gas</span>-cooled reactor is thereby enhanced.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25761782','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25761782"><span>Protein structural dynamics at the <span class="hlt">gas</span>/water interface examined by hydrogen <span class="hlt">exchange</span> mass spectrometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xiao, Yiming; Konermann, Lars</p> <p>2015-08-01</p> <p><span class="hlt">Gas</span>/water interfaces (such as air bubbles or foam) are detrimental to the stability of proteins, often causing aggregation. This represents a potential problem for industrial processes, for example, the production and handling of protein drugs. Proteins possess surfactant-like properties, resulting in a high affinity for <span class="hlt">gas</span>/water interfaces. The tendency of previously buried nonpolar residues to maximize contact with the <span class="hlt">gas</span> phase can cause significant structural distortion. Most earlier studies in this area employed spectroscopic tools that could only provide limited information. Here we use hydrogen/deuterium <span class="hlt">exchange</span> (HDX) mass spectrometry (MS) for probing the conformational dynamics of the model protein myoglobin (Mb) in the presence of N(2) bubbles. HDX/MS relies on the principle that unfolded and/or highly dynamic regions undergo faster deuteration than tightly folded segments. In bubble-free solution Mb displays EX2 behavior, reflecting the occurrence of short-lived excursions to partially unfolded conformers. A dramatically different behavior is seen in the presence of N(2) bubbles; EX2 dynamics still take place, but in addition the protein shows EX1 behavior. The latter results from interconversion of the native state with conformers that are globally unfolded and long-lived. These unfolded species likely correspond to Mb that is adsorbed to the surface of <span class="hlt">gas</span> bubbles. N(2) sparging also induces aggregation. To explain the observed behavior we propose a simple model, that is, "semi-unfolded" ↔ "native" ↔ "globally unfolded" → "aggregated". This model quantitatively reproduces the experimentally observed kinetics. To the best of our knowledge, the current study marks the first exploration of surface denaturation phenomena by HDX/MS. © 2015 The Protein Society.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/7798448','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/7798448"><span>Influence of continuous haemofiltration-related hypothermia on haemodynamic variables and <span class="hlt">gas</span> <span class="hlt">exchange</span> in septic patients.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Matamis, D; Tsagourias, M; Koletsos, K; Riggos, D; Mavromatidis, K; Sombolos, K; Bursztein, S</p> <p>1994-07-01</p> <p>To investigate the influence of continuous haemofiltration (CHF) on haemodynamics, <span class="hlt">gas</span> <span class="hlt">exchange</span> and core temperature in critically ill septic patients with acute renal failure. In 20 patients (17 male, 3 female) ultrafiltration rate, core temperature, <span class="hlt">gas</span> <span class="hlt">exchange</span> and haemodynamic variables were measured at regular intervals during the first 48 h of haemofiltration. Baseline data were compared to those obtained 30 min after initiating CHF and also to those during hypothermia (if observed). Haemodynamic variables remained remarkably constant throughout the study period. In patients with a relatively low ultrafiltration rate (855 +/- 278 ml/h) temperature did not change, while in patients with a high ultrafiltration rate (1468 +/- 293 ml/h) core temperature significantly decreased from 37.6 +/- 0.9 degrees C to 34.8 +/- 0.8 degrees C (p < 0.001). There was a statistically significant correlation between temperature decrease and ultrafiltration rate (r = -0.68, Y = 1.8-0.003 X, p < 0.01). Hypothermic patients also showed a mean decrease in VO2 from 141 +/- 22 ml/min/m2 to 112 +/- 22 ml/min/m2 (p < 0.01) with a concomitant increase in PaO2 from 103 +/- 37 mmHg to 140 +/- 42 mmHg (p < 0.001) and in PvO2 from 35 +/- 4 mmHg to 41 +/- 5 mmHg (p < 0.001). 1) Continuous haemofiltration does not cause significant alternations in haemodynamic variables. 2) Hypothermia frequently occurs in patients undergoing continuous haemofiltration with high ultrafiltration rates. These hypothermic patients show a reduction in VO2 leading to an increase in PvO2 and PaO2. This mild hypothermia in these circumstances has no evident deleterious effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29471273','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29471273"><span>Effect of simultaneously induced environmental stimuli on electrical signalling and <span class="hlt">gas</span> <span class="hlt">exchange</span> in maize plants.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vuralhan-Eckert, Jasmin; Lautner, Silke; Fromm, Jörg</p> <p>2018-04-01</p> <p>Electrical signalling in response to environmental stimuli is a well-known phenomenon in higher plants. For example, in maize, different stimuli, such as wounding or re-irrigation after drought, incite characteristic electrical signals which have quite particular effects on <span class="hlt">gas</span> <span class="hlt">exchange</span>. What is less well understood is how plants (specifically maize) respond when two different environmental stimuli are applied simultaneously. To explore this, a three-stage experiment was designed. In the first stage, drought conditions were simulated by decreasing the soil water content to 30-40 % of field capacity. In these conditions, and in contrast to well-watered plants, the maize exhibited only 60-70% of the original level of stomatal conductance and 50-60 % of the original photosynthesis rate. In the second stage of the experiment the plants were re-irrigated and heat stimulated separately. Re-irrigation led to specific electrical signals followed by a gradual increase of <span class="hlt">gas</span> <span class="hlt">exchange</span>. In contrast, after heat stimulation of a leaf an electrical signal was evoked that reduced the net CO 2 -uptake rate as well as stomatal conductance. In the third stage, to elucidate how plants process simultaneous re-irrigation and heat stimulation, the drought-stressed maize plants were re-watered and heat-stimulated at the same time. Results showed a two phase response. In the first phase there was a rapid decrease in both the CO 2 uptake rate and the stomatal conductance, while in the second phase each of these parameters increased gradually. Thus, the results strongly support the view that the responses from both stimuli were combined, indicating that maize plants can process simultaneously applied stimuli. Copyright © 2018 Elsevier GmbH. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/21355','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/21355"><span>Radiation-use efficiency and <span class="hlt">gas</span> <span class="hlt">exchange</span> responses to water and nutrient availability in irrigated and fertilized stands of sweetgum and sycamore</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Christopher B. Allen; Rodney E. Will; Robert C. McGravey; David R. Coyle; Mark D. Coleman</p> <p>2005-01-01</p> <p>We investigated how water and nutrient availability affect radiation-use effeciency (e) and assessed leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> as a possible mechanism for shifts in e. We measured aboveground net primary production (ANPP) and annual photosynthetically active radiation (PAR) capture to calculate e as well as leaf-level physiological variables (light-saturated net photosynthesis...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SPIE10421E..0IB','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SPIE10421E..0IB"><span>Low-cost photonic sensors for carbon dioxide <span class="hlt">exchange</span> rate measurement</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bieda, Marcin S.; Sobotka, Piotr; Lesiak, Piotr; Woliński, Tomasz R.</p> <p>2017-10-01</p> <p>Carbon dioxide (CO2) measurement has an important role in atmosphere monitoring. Usually, two types of measurements are carried out. The first one is based on <span class="hlt">gas</span> concentration measurement while the second involves <span class="hlt">gas</span> <span class="hlt">exchange</span> rate measurement between earth surface and atmosphere [1]. There are several methods which allow <span class="hlt">gas</span> concentration measurement. However, most of them require expensive instrumentation or large devices (i.e. <span class="hlt">gas</span> chambers). In order to precisely measure either CO2 concentration or CO2 <span class="hlt">exchange</span> rate, preferably a sensors network should be used. These sensors must have small dimensions, low power consumption, and they should be cost-effective. Therefore, this creates a great demand for a robust low-power and low-cost CO2 sensor [2,3]. As a solution, we propose a photonic sensor that can measure CO2 concentration and also can be used to measure <span class="hlt">gas</span> <span class="hlt">exchange</span> by using the Eddy covariance method [1].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22751459','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22751459"><span>Hepatopulmonary syndrome: update on pathogenesis and clinical features.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Junlan; Fallon, Michael B</p> <p>2012-09-01</p> <p>Hepatopulmonary syndrome (HPS) is a serious vascular complication of liver disease that occurs in 5-32% of patients with cirrhosis. The presence of HPS markedly increases mortality. No effective medical therapies are currently available and liver transplantation is the only established treatment option for HPS. The definition and diagnosis of HPS are established by the presence of a triad of liver disease with intrapulmonary vascular dilation that causes <span class="hlt">abnormal</span> arterial <span class="hlt">gas</span> <span class="hlt">exchange</span>. Experimental biliary cirrhosis induced by common bile duct ligation in the rat reproduces the pulmonary vascular and <span class="hlt">gas</span> <span class="hlt">exchange</span> <span class="hlt">abnormalities</span> of human HPS and serves as a pertinent animal model. Pulmonary microvascular dilation and angiogenesis are two central pathogenic features that drive <span class="hlt">abnormal</span> pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> in experimental HPS, and thus might underlie HPS in humans. Defining the mechanisms involved in the microvascular alterations of HPS has the potential to lead to effective medical therapies. This Review focuses on the current understanding of the pathogenesis, clinical features and management of HPS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70020196','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70020196"><span><span class="hlt">Abnormally</span> high formation pressures, Potwar Plateau, Pakistan</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Law, B.E.; Shah, S.H.A.; Malik, M.A.</p> <p>1998-01-01</p> <p><span class="hlt">Abnormally</span> high formation pressures in the Potwar Plateau of north-central Pakistan are major obstacles to oil and <span class="hlt">gas</span> exploration. Severe drilling problems associated with high pressures have, in some cases, prevented adequate evaluation of reservoirs and significantly increased drilling costs. Previous investigations of <span class="hlt">abnormal</span> pressure in the Potwar Plateau have only identified <span class="hlt">abnormal</span> pressures in Neogene rocks. We have identified two distinct pressure regimes in this Himalayan foreland fold and thrust belt basin: one in Neogene rocks and another in pre-Neogene rocks. Pore pressures in Neogene rocks are as high as lithostatic and are interpreted to be due to tectonic compression and compaction disequilibrium associated with high rates of sedimentation. Pore pressure gradients in pre-Neogene rocks are generally less than those in Neogene rocks, commonly ranging from 0.5 to 0.7 psi/ft (11.3 to 15.8 kPa/m) and are most likely due to a combination of tectonic compression and hydrocarbon generation. The top of <span class="hlt">abnormally</span> high pressure is highly variable and doesn't appear to be related to any specific lithologic seal. Consequently, attempts to predict the depth to the top of overpressure prior to drilling are precluded.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27714456','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27714456"><span>Characterizing cerebral and locomotor muscle oxygenation to incremental ramp exercise in healthy children: relationship with pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vandekerckhove, Kristof; Coomans, Ilse; Moerman, Annelies; De Wolf, Daniel; Boone, Jan</p> <p>2016-12-01</p> <p>To characterize the oxygenation responses at cerebral and locomotor muscle level to incremental exercise in children and to assess the interrelationship with the pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> responses. Eighteen children (9 boys, 9 girls) (mean age 10.9 ± 1.0 years) performed incremental cycle ramp exercise to exhaustion. The concentration of cerebral and muscle oxygenated (O 2 Hb) and deoxygenated (HHb) hemoglobin (by means of near-infrared spectroscopy) and pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span> was recorded. Cerebral and muscle O 2 Hb and HHb values were expressed as functions of oxygen uptake (VO 2 ) and breakpoints were detected by means of double linear model analysis. The respiratory compensation point (RCP) was determined. The breakpoints in cerebral and muscle O 2 Hb and HHb were compared and correlated to RCP. The subjects reached peak power output of 105 ± 18 W and VO 2peak of 43.5 ± 7.0 ml min -1  kg -1 . Cerebral O 2 Hb increased to an intensity of 89.4 ± 5.5 %VO 2peak , where a breakpoint occurred at which cerebral O 2 Hb started to decrease. Cerebral HHb increased slightly to 88.1 ± 4.8 %VO 2peak , at which the increase was accelerated. Muscle HHb increased to 90.5 ± 4.8 %VO 2peak where a leveling-off occurred. RCP occurred at 89.3 ± 4.3 %VO 2peak . The breakpoints and RCP did not differ significantly (P = 0.13) and were strongly correlated (r > 0.70, P < 0.05). There were no differences between boys and girls (P = 0.43) and there was no significant correlation with VO 2peak (P > 0.05). It was shown that cerebral and muscle oxygenation responses undergo significant changes as work rate increases and show breakpoints in the ongoing response at high intensity (85-95 %VO 2peak ). These breakpoints are strongly interrelated and associated with changes in pulmonary <span class="hlt">gas</span> <span class="hlt">exchange</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120003323','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120003323"><span>Scientific Verification Test of Orbitec Deployable Vegetable Production System for Salad Crop Growth on ISS- <span class="hlt">Gas</span> <span class="hlt">Exchange</span> System design and function</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Eldemire, Ashleigh</p> <p>2007-01-01</p> <p>The ability to produce and maintain salad crops during long term missions would be a great benefit to NASA; the renewable food supply would save cargo space, weight and money. The ambient conditions of previous ground controlled crop plant experiments do not reflect the microgravity and high CO2 concentrations present during orbit. It has been established that microgravity does not considerably alter plant growth. (Monje, Stutte, Chapman, 2005). To support plants in a space-craft environment efficient and effective lighting and containment units are necessary. Three lighting systems were previously evaluated for radish growth in ambient air; fluorescent lamps in an Orbitec Biomass Production System Educational (BPSE), a combination of red, blue, and green LED's in a Deployable Vegetable Production System (Veggie), and a combination of red and blue LED's in a Veggie. When mass measurements compared the entire possible growing area vs. power consumed by the respective units, the Veggies clearly exceeded the BPSE indicating that the LED units were a more resource efficient means of growing radishes under ambient conditions in comparison with fluorescent lighting. To evaluate the most productive light treatment system for a long term space mission a more closely simulated ISS environment is necessary. To induce a CO2 dense atmosphere inside the Veggie's and BPSE a <span class="hlt">gas</span> <span class="hlt">exchange</span> system has been developed to maintain a range of 1000-1200 ppm CO2 during a 21-day light treatment experiment. This report details the design and function of the <span class="hlt">gas</span> <span class="hlt">exchange</span> system. The rehabilitation, trouble shooting, maintenance and testing of the <span class="hlt">gas</span> <span class="hlt">exchange</span> system have been my major assignments. I have also contributed to the planting, daily measurements and harvesting of the radish crops 21-day light treatment verification test.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27558796','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27558796"><span>Genotypic variation in biomass allocation in response to field drought has a greater affect on yield than <span class="hlt">gas</span> <span class="hlt">exchange</span> or phenology.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Edwards, Christine E; Ewers, Brent E; Weinig, Cynthia</p> <p>2016-08-24</p> <p>Plant performance in agricultural and natural settings varies with moisture availability, and understanding the range of potential drought responses and the underlying genetic architecture is important for understanding how plants will respond to both natural and artificial selection in various water regimes. Here, we raised genotypes of Brassica rapa under well-watered and drought treatments in the field. Our primary goal was to understand the genetic architecture and yield effects of different drought-escape and dehydration-avoidance strategies. Drought treatments reduced soil moisture by 62 % of field capacity. Drought decreased biomass accumulation and fruit production by as much as 48 %, whereas instantaneous water-use efficiency and root:shoot ratio increased. Genotypes differed in the mean value of all traits and in the sensitivity of biomass accumulation, root:shoot ratio, and fruit production to drought. Bivariate correlations involving <span class="hlt">gas-exchange</span> and phenology were largely constant across environments, whereas those involving root:shoot varied across treatments. Although root:shoot was typically unrelated to <span class="hlt">gas-exchange</span> or yield under well-watered conditions, genotypes with low to moderate increases in root:shoot allocation in response to drought survived the growing season, maintained maximum photosynthesis levels, and produced more fruit than genotypes with the greatest root allocation under drought. QTL for <span class="hlt">gas-exchange</span> and yield components (total biomass or fruit production) had common effects across environments while those for root:shoot were often environment-specific. Increases in root allocation beyond those needed to survive and maintain favorable water relations came at the cost of fruit production. The environment-specific effects of root:shoot ratio on yield and the differential expression of QTL for this trait across water regimes have important implications for efforts to improve crops for drought resistance.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/865056','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/865056"><span>Heat <span class="hlt">exchanger</span> for coal gasification process</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Blasiole, George A.</p> <p>1984-06-19</p> <p>This invention provides a heat <span class="hlt">exchanger</span>, particularly useful for systems requiring cooling of hot particulate solids, such as the separated fines from the product <span class="hlt">gas</span> of a carbonaceous material gasification system. The invention allows effective cooling of a hot particulate in a particle stream (made up of hot particulate and a <span class="hlt">gas</span>), using gravity as the motive source of the hot particulate. In a preferred form, the invention substitutes a tube structure for the single wall tube of a heat <span class="hlt">exchanger</span>. The tube structure comprises a tube with a core disposed within, forming a cavity between the tube and the core, and vanes in the cavity which form a flow path through which the hot particulate falls. The outside of the tube is in contact with the cooling fluid of the heat <span class="hlt">exchanger</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19778365','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19778365"><span>Why and how terrestrial plants <span class="hlt">exchange</span> gases with air.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cieslik, S; Omasa, K; Paoletti, E</p> <p>2009-11-01</p> <p>This work is intended as a review of <span class="hlt">gas</span> <span class="hlt">exchange</span> processes between the atmosphere and the terrestrial vegetation, which have been known for more than two centuries since the discovery of photosynthesis. The physical and biological mechanisms of <span class="hlt">exchange</span> of carbon dioxide, water vapour, volatile organic compounds emitted by plants and air pollutants taken up by them, is critically reviewed. The role of stomatal physiology is emphasised, as it controls most of these processes. The techniques used for measurement of <span class="hlt">gas</span> <span class="hlt">exchange</span> fluxes between the atmosphere and vegetation are outlined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720040815&hterms=inequality&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dinequality','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720040815&hterms=inequality&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dinequality"><span>Effect of stratified inequality of blood flow on <span class="hlt">gas</span> <span class="hlt">exchange</span> in liquid-filled lungs.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>West, J. B.; Maloney, J. E.; Castle, B. L.</p> <p>1972-01-01</p> <p>This investigation set out to answer two questions: (1) are the distal alveoli in the terminal lung units less well perfused than the proximal alveoli, i.e., is there stratification of blood flow; and (2) if so, does this enhance <span class="hlt">gas</span> <span class="hlt">exchange</span> in the presence of stratified inequality of ventilation. Excised dog lungs were ventilated with saline and perfused with blood. Following single inspirations of xenon 133 in saline and various periods of breath holding, the expired xenon concentration against volume was measured and it confirmed marked stratified inequality of ventilation under these conditions. By measuring the rate of depletion of xenon from alveoli during a period of blood flow, we showed that the alveoli which emptied at the end of expiration had 16% less blood flow than those exhaling earlier. However, by measuring the xenon concentration in pulmonary venous blood, we found that about 10% less tracer was transferred from the alveoli into the blood when the inspired xenon was stratified within the respiratory zone. Thus while stratification of blood flow was confirmed, it was shown to impair rather than enhance the efficiency of <span class="hlt">gas</span> transfer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17664033','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17664033"><span>Carbon source/sink function of a subtropical, eutrophic lake determined from an overall mass balance and a <span class="hlt">gas</span> <span class="hlt">exchange</span> and carbon burial balance.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Hong; Xing, Yangping; Xie, Ping; Ni, Leyi; Rong, Kewen</p> <p>2008-02-01</p> <p>Although studies on carbon burial in lake sediments have shown that lakes are disproportionately important carbon sinks, many studies on gaseous carbon <span class="hlt">exchange</span> across the water-air interface have demonstrated that lakes are supersaturated with CO(2) and CH(4) causing a net release of CO(2) and CH(4) to the atmosphere. In order to more accurately estimate the net carbon source/sink function of lake ecosystems, a more comprehensive carbon budget is needed, especially for gaseous carbon <span class="hlt">exchange</span> across the water-air interface. Using two methods, overall mass balance and <span class="hlt">gas</span> <span class="hlt">exchange</span> and carbon burial balance, we assessed the carbon source/sink function of Lake Donghu, a subtropical, eutrophic lake, from April 2003 to March 2004. With the overall mass balance calculations, total carbon input was 14 905 t, total carbon output was 4950 t, and net carbon budget was +9955 t, suggesting that Lake Donghu was a great carbon sink. For the <span class="hlt">gas</span> <span class="hlt">exchange</span> and carbon burial balance, gaseous carbon (CO(2) and CH(4)) emission across the water-air interface totaled 752 t while carbon burial in the lake sediment was 9477 t. The ratio of carbon emission into the atmosphere to carbon burial into the sediment was only 0.08. This low ratio indicates that Lake Donghu is a great carbon sink. Results showed good agreement between the two methods with both showing Lake Donghu to be a great carbon sink. This results from the high primary production of Lake Donghu, substantive allochthonous carbon inputs and intensive anthropogenic activity. Gaseous carbon emission accounted for about 15% of the total carbon output, indicating that the total output would be underestimated without including gaseous carbon <span class="hlt">exchange</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22766042','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22766042"><span>Drought effect on growth, <span class="hlt">gas</span> <span class="hlt">exchange</span> and yield, in two strains of local barley Ardhaoui, under water deficit conditions in southern Tunisia.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thameur, Afwa; Lachiheb, Belgacem; Ferchichi, Ali</p> <p>2012-12-30</p> <p>Two local barley strains cv. Ardhaoui originated from Tlalit and Switir, sourthern Tunisia were grown in pots in a glasshouse assay, under well-watered conditions for a month. Plants were then either subjected to water deficit (treatment) or continually well-watered (control). Control pots were irrigated several times each week to maintain soil moisture near field capacity (FC), while stress pots experienced soil drying by withholding irrigation until they reached 50% of FC. Variation in relative water content, leaf area, leaf appearance rate and leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> (i.e. net CO(2) assimilation rate (A), transpiration (E), and stomatal conductance (gs)) in response to water deficit was investigated. High leaf relative water content (RWC) was maintained in Tlalit by stomatal closure and a reduction of leaf area. Reduction in leaf area was due to decline in leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> during water deficit. Tlalit was found to be drought tolerant and able to maintain higher leaf RWC under drought conditions. Water deficit treatment reduced stomatal conductance by 43% at anthesis. High net CO(2) assimilation rate under water deficit was associated with high RWC (r = 0.998; P < 0.01). Decline in net CO(2) assimilation rate was due mainly to stomatal closure. Significant differences between studied strains in leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> parameters were found, which can give some indications on the degree of drought tolerance. Thus, the ability of the low leaf area plants to maintain higher RWC could explain the differences in drought tolerance in studied barley strains. Results showed that Tlalit showed to be more efficient and more productive than Switir. Copyright © 2012 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12680524','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12680524"><span>The effect of heat and moisture <span class="hlt">exchanger</span> and <span class="hlt">gas</span> flow on humidity and temperature in a circle anaesthetic system.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Poopalalingam, R; Goh, M H; Chan, Y W</p> <p>2002-11-01</p> <p>The aim of the study was to measure the humidity and temperature of the inspired <span class="hlt">gas</span> in a circle absorber system at fresh <span class="hlt">gas</span> flows of 11/min and 31/min and assess the need of a heat and moisture <span class="hlt">exchanger</span> (HME). This prospective randomised controlled study received the Hospital Ethics Committee approval and informed consent. Forty adult ASA 1 and 11 patients were randomised into four groups to receive with or without HME fresh <span class="hlt">gas</span> flow of 1L/min or 3L/min. Temperature and the relative humidity readings were taken at the start and every 10 minutes for the first hour of anaesthesia. There was a significantly higher relative humidity, absolute humidity and temperatures of the inspired gases at fresh <span class="hlt">gas</span> flow of 1L/min and 3L/min with a HME compared to 3L/min without HME. Patients receiving fresh <span class="hlt">gas</span> flows of lL/min had higher relative and absolute humidity than patients with fresh <span class="hlt">gas</span> flows of 3L/min. However, the addition of the HME improved the absolute and relative humidity of the inspired <span class="hlt">gas</span> in patients receiving fresh <span class="hlt">gas</span> flow of 3l/min to a comparable level. However, the addition of a HME to a fresh <span class="hlt">gas</span> flow of 1L/min did not significantly improve the humidity of the inspired <span class="hlt">gas</span>. This suggests that the inherent humidifying property of the circle system at low fresh <span class="hlt">gas</span> flow of 1L/min was sufficient in short surgeries lasting less than one hour and that the addition of a HME may not be necessary.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870011369&hterms=Exchange+gaseous&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DExchange%2Bgaseous%257D','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870011369&hterms=Exchange+gaseous&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DExchange%2Bgaseous%257D"><span>Kinetic model for the vibrational energy <span class="hlt">exchange</span> in flowing molecular <span class="hlt">gas</span> mixtures. Ph.D. Thesis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Offenhaeuser, F.</p> <p>1987-01-01</p> <p>The present study is concerned with the development of a computational model for the description of the vibrational energy <span class="hlt">exchange</span> in flowing <span class="hlt">gas</span> mixtures, taking into account a given number of energy levels for each vibrational degree of freedom. It is possible to select an arbitrary number of energy levels. The presented model uses values in the range from 10 to approximately 40. The distribution of energy with respect to these levels can differ from the equilibrium distribution. The kinetic model developed can be employed for arbitrary gaseous mixtures with an arbitrary number of vibrational degrees of freedom for each type of <span class="hlt">gas</span>. The application of the model to CO2-H2ON2-O2-He mixtures is discussed. The obtained relations can be utilized in a study of the suitability of radiation-related transitional processes, involving the CO2 molecule, for laser applications. It is found that the computational results provided by the model agree very well with experimental data obtained for a CO2 laser. Possibilities for the activation of a 16-micron and 14-micron laser are considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/5874683-method-dehydrating-natural-gas','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5874683-method-dehydrating-natural-gas"><span>Method of dehydrating natural <span class="hlt">gas</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Wells, R. E.</p> <p>1985-01-01</p> <p>A method for dehydration of natural <span class="hlt">gas</span> is provided wherein well head <span class="hlt">gas</span> is supplied to a three-phase inlet separator, the vapor mixture of natural <span class="hlt">gas</span> and water removed from that inlet separator means is supplied to a turboexpander, and the resulting refrigerated mixture of natural <span class="hlt">gas</span> and condensed water vapor is supplied to a multi-phase outlet separator. The turboexpander may have integral means for subsequent compression of the refrigerated mixture and may be coupled through reduction gears to a means for generating electricity. A portion of the refrigerated mixture may be connected to a heat <span class="hlt">exchanger</span> for cooling themore » well head natural <span class="hlt">gas</span> prior to entry into the inlet separator. The flow of refrigerated mixture to this heat <span class="hlt">exchanger</span> may be controlled by a temperature sensitive valve downstream of the heat <span class="hlt">exchanger</span>. Methanol may be injected into the vapor mixture prior to entry into the turboexpander. The flow of methanol into the vapor mixture may be controlled by a valve sensitive to the flow rate of the vapor mixture and the water vapor content of the refrigerated mixture. Natural <span class="hlt">gas</span> vapor from the outlet separator may be recirculated through the turboexpander if the output water vapor content of the natural <span class="hlt">gas</span> vapor stream is too high.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3081140','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3081140"><span>Hyperpolarized Xenon-129 <span class="hlt">Gas-Exchange</span> Imaging of Lung Microstructure: First Case Studies in Subjects with Obstructive Lung Disease</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dregely, Isabel; Mugler, John P.; Ruset, Iulian C.; Altes, Talissa A.; Mata, Jaime F.; Miller, G. Wilson; Ketel, Jeffrey; Ketel, Steve; Distelbrink, Jan; Hersman, F.W.; Ruppert, Kai</p> <p>2011-01-01</p> <p>Purpose To develop and test a method to non-invasively assess the functional lung microstructure. Materials and Methods The Multiple <span class="hlt">exchange</span> time Xenon polarization Transfer Contrast technique (MXTC) encodes xenon <span class="hlt">gas-exchange</span> contrast at multiple delay times permitting two lung-function parameters to be derived: 1) MXTC-F, the long <span class="hlt">exchange</span>-time depolarization value, which is proportional to the tissue to alveolar-volume ratio and 2) MXTC-S, the square root of the xenon <span class="hlt">exchange</span>-time constant, which characterizes thickness and composition of alveolar septa. Three healthy volunteers, one asthmatic and two COPD (GOLD stage I and II) subjects were imaged with MXTC MRI. In a subset of subjects, hyperpolarized xenon-129 ADC MRI and CT imaging were also performed. Results The MXTC-S parameter was found to be elevated in subjects with lung disease (p-value = 0.018). In the MXTC-F parameter map it was feasible to identify regional loss of functional tissue in a COPD patient. Further, the MXTC-F map showed excellent regional correlation with CT and ADC (ρ ≥ 0.90) in one COPD subject. Conclusion The functional tissue-density parameter MXTC-F showed regional agreement with other imaging techniques. The newly developed parameter MXTC-S, which characterizes the functional thickness of alveolar septa, has potential as a novel biomarker for regional parenchymal inflammation or thickening. PMID:21509861</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://lofe.dukejournals.org/content/2/1.abstract','USGSPUBS'); return false;" href="http://lofe.dukejournals.org/content/2/1.abstract"><span>Air-water oxygen <span class="hlt">exchange</span> in a large whitewater river</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hall, Robert O.; Kennedy, Theodore A.; Rosi-Marshall, Emma J.</p> <p>2012-01-01</p> <p>Air-water <span class="hlt">gas</span> <span class="hlt">exchange</span> governs fluxes of <span class="hlt">gas</span> into and out of aquatic ecosystems. Knowing this flux is necessary to calculate <span class="hlt">gas</span> budgets (i.e., O2) to estimate whole-ecosystem metabolism and basin-scale carbon budgets. Empirical data on rates of <span class="hlt">gas</span> <span class="hlt">exchange</span> for streams, estuaries, and oceans are readily available. However, there are few data from large rivers and no data from whitewater rapids. We measured <span class="hlt">gas</span> transfer velocity in the Colorado River, Grand Canyon, as decline in O2 saturation deficit, 7 times in a 28-km segment spanning 7 rapids. The O2 saturation deficit exists because of hypolimnetic discharge from Glen Canyon Dam, located 25 km upriver from Lees Ferry. <span class="hlt">Gas</span> transfer velocity (k600) increased with slope of the immediate reach. k600 was -1 in flat reaches, while k600 for the steepest rapid ranged 3600-7700 cm h-1, an extremely high value of k600. Using the rate of <span class="hlt">gas</span> <span class="hlt">exchange</span> per unit length of water surface elevation (Kdrop, m-1), segment-integrated k600 varied between 74 and 101 cm h-1. Using Kdrop we scaled k600 to the remainder of the Colorado River in Grand Canyon. At the scale corresponding to the segment length where 80% of the O2 <span class="hlt">exchanged</span> with the atmosphere (mean length = 26.1 km), k600 varied 4.5-fold between 56 and 272 cm h-1 with a mean of 113 cm h-1. <span class="hlt">Gas</span> transfer velocity for the Colorado River was higher than those from other aquatic ecosystems because of large rapids. Our approach of scaling k600 based on Kdrop allows comparing <span class="hlt">gas</span> transfer velocity across rivers with spatially heterogeneous morphology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23238597','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23238597"><span>Water-<span class="hlt">gas</span> <span class="hlt">exchange</span> of organochlorine pesticides at Lake Chaohu, a large Chinese lake.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ouyang, Hui-Ling; He, Wei; Qin, Ning; Kong, Xiang-Zhen; Liu, Wen-Xiu; He, Qi-Shuang; Yang, Chen; Jiang, Yu-Jiao; Wang, Qing-Mei; Yang, Bin; Xu, Fu-Liu</p> <p>2013-04-01</p> <p>Organochlorine pesticides (OCPs), a potential threat to ecosystems and human health, are still widely residual in the environment. The residual levels of OCPs in the water and <span class="hlt">gas</span> phase were monitored in Lake Chaohu, a large Chinese lake, from March 2010 to February 2011. Nineteen types of OCPs were detected in the water with a total concentration of 7.27 ± 3.32 ng/l. Aldrin, DDTs and HCHs were the major OCPs in the water, accounting for 38.3%, 28.9% and 23.6% of the total, respectively. The highest mean concentration (12.32 ng/l) in the water was found in September, while the lowest (1.74 ng/l) was found in November. Twenty types of gaseous OCPs were detected in the atmosphere with a total concentration of 542.0 ± 636.5 pg/m(3). Endosulfan, DDTs and chlordane were the major gaseous OCPs in the atmosphere, accounting for 48.9%, 22.5% and 14.4% of the total, respectively. The mean concentration of gaseous OCPs was significantly higher in summer than in winter. o,p'-DDE was the main metabolite of DDT in both the water and <span class="hlt">gas</span> phase. Of the HCHs, 52.3% existed as β-HCH in the water, while α-HCH (37.9%) and γ-HCH (30.9%) were dominant isomers in the <span class="hlt">gas</span> phase. The average fluxes were -21.11, -3.30, -152.41, -35.50 and -1314.15 ng/(m(2) day) for α-HCH, γ-HCH, HCB, DDT and DDE, respectively. The water-<span class="hlt">gas</span> <span class="hlt">exchanges</span> of the five types of OCPs indicate that water was the main potential source of gaseous OCPs in the atmosphere. A sensitivity analysis indicated that the water-<span class="hlt">gas</span> flux of α-HCH, γ-HCH and DDT is more vulnerable than that of HCB and DDE to the variation of the parameters. The possible source of the HCHs in the water was from the historical usage of lindane; however, that in the air was mainly from the recent usage of lindane. The technical DDT and dicofol might be the source of DDTs in the water and air.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1250452','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1250452"><span><span class="hlt">Gas</span> magnetometer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert</p> <p>2016-05-03</p> <p>Measurement of a precessional rate of a <span class="hlt">gas</span>, such as an alkali <span class="hlt">gas</span>, in a magnetic field is made by promoting a non-uniform precession of the <span class="hlt">gas</span> in which substantially no net magnetic field affects the <span class="hlt">gas</span> during a majority of the precession cycle. This allows sensitive gases that would be subject to spin-<span class="hlt">exchange</span> collision de-phasing to be effectively used for extremely sensitive measurements in the presence of an environmental magnetic field such as the Earth's magnetic field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015BGeo...12.2101B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015BGeo...12.2101B"><span>Greenhouse <span class="hlt">gas</span> <span class="hlt">exchange</span> of rewetted bog peat extraction sites and a Sphagnum cultivation site in northwest Germany</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beyer, C.; Höper, H.</p> <p>2015-04-01</p> <p>During the last decades an increasing area of drained peatlands has been rewetted. Especially in Germany, rewetting is the principal treatment on cutover sites when peat extraction is finished. The objectives are bog restoration and the reduction of greenhouse <span class="hlt">gas</span> (GHG) emissions. The first sites were rewetted in the 1980s. Thus, there is a good opportunity to study long-term effects of rewetting on greenhouse <span class="hlt">gas</span> <span class="hlt">exchange</span>, which has not been done so far on temperate cutover peatlands. Moreover, Sphagnum cultivating may become a new way to use cutover peatlands and agriculturally used peatlands as it permits the economical use of bogs under wet conditions. The climate impact of such measures has not been studied yet. We conducted a field study on the <span class="hlt">exchange</span> of carbon dioxide, methane and nitrous oxide at three rewetted sites with a gradient from dry to wet conditions and at a Sphagnum cultivation site in NW Germany over the course of more than 2 years. <span class="hlt">Gas</span> fluxes were measured using transparent and opaque closed chambers. The ecosystem respiration (CO2) and the net ecosystem <span class="hlt">exchange</span> (CO2) were modelled at a high temporal resolution. Measured and modelled values fit very well together. Annually cumulated <span class="hlt">gas</span> flux rates, net ecosystem carbon balances (NECB) and global warming potential (GWP) balances were determined. The annual net ecosystem <span class="hlt">exchange</span> (CO2) varied strongly at the rewetted sites (from -201.7 ± 126.8 to 29.7± 112.7g CO2-C m-2 a-1) due to differing weather conditions, water levels and vegetation. The Sphagnum cultivation site was a sink of CO2 (-118.8 ± 48.1 and -78.6 ± 39.8 g CO2-C m-2 a-1). The annual CH4 balances ranged between 16.2 ± 2.2 and 24.2 ± 5.0g CH4-C m-2 a-1 at two inundated sites, while one rewetted site with a comparatively low water level and the Sphagnum farming site show CH4 fluxes close to 0. The net N2O fluxes were low and not significantly different between the four sites. The annual NECB was between -185.5 ± 126.9 and 49</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.B21B0329I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.B21B0329I"><span>Greenhouse-<span class="hlt">gas</span> <span class="hlt">exchange</span> of croplands worldwide: a process-based model simulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Inatomi, M.; Ito, A.</p> <p>2009-12-01</p> <p>Croplands cover about 15% of the land surface, and play unique roles in global biogeochemical cycles. Especially, greenhouse <span class="hlt">gas</span> budget of croplands is important for climate projection in the future and for mitigation toward climate stabilization. Sustainable cropland is carbon-neutral (i.e., neither a sink nor a source of CO2 for a long time), but those in developed countries consume fossil fuels for agricultural operations and releases CO2 as revealed by LCAs. Paddy field is one of the substantial sources of CH4, and cropland may be the largest anthropogenic source of N2O. However, these features have not been evaluated and discussed using a spatial-explicit comprehensive framework at the global scale. This study applies a process-based terrestrial ecosystem model (VISIT) to worldwide croplands. <span class="hlt">Exchange</span> of CO2 is simulated as a difference between photosynthesis and respiration, each of which is calculated in a biogeochemical carbon cycle scheme. Net carbon budget accounts for carbon flows by planting, compost input, and harvest. <span class="hlt">Exchange</span> of CH4 is simulated as a difference between oxidation by aerobic soils and production by anaerobic soils, each of which is calculated using mechanistic schemes. Emission of N2O from nitrification and denitrification is simulated with a semi-mechanistic scheme on the basis of leaky-pipe concept. We are also validating the model through comparison with chamber and tower flux measurements. Global simulations were conducted during a period from 1901 to 2100 on the basis of historical and projected climate and land-use conditions, at a spatial resolution of 0.5 x 0.5 degree. Cropland type and distribution was derived from SAGE-HYDE dataset and country-base fertilizer input was obtained from FAOSTAT. Our preliminary simulation for the 1990s estimated that croplands are a net sink of CO2 by 1.1 Gt C/yr; this sink is offset by emission by food consumption. Paddy fields are estimated to release CH4 by 46 Tg CH4/yr, and croplands</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1174546','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1174546"><span>Circulating heat <span class="hlt">exchangers</span> for oscillating wave engines and refrigerators</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Swift, Gregory W.; Backhaus, Scott N.</p> <p>2003-10-28</p> <p>An oscillating-wave engine or refrigerator having a regenerator or a stack in which oscillating flow of a working <span class="hlt">gas</span> occurs in a direction defined by an axis of a trunk of the engine or refrigerator, incorporates an improved heat <span class="hlt">exchanger</span>. First and second connections branch from the trunk at locations along the axis in selected proximity to one end of the regenerator or stack, where the trunk extends in two directions from the locations of the connections. A circulating heat <span class="hlt">exchanger</span> loop is connected to the first and second connections. At least one fluidic diode within the circulating heat <span class="hlt">exchanger</span> loop produces a superimposed steady flow component and oscillating flow component of the working <span class="hlt">gas</span> within the circulating heat <span class="hlt">exchanger</span> loop. A local process fluid is in thermal contact with an outside portion of the circulating heat <span class="hlt">exchanger</span> loop.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3283644','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3283644"><span>In Vivo MR Imaging of Pulmonary Perfusion and <span class="hlt">Gas</span> <span class="hlt">Exchange</span> in Rats via Continuous Extracorporeal Infusion of Hyperpolarized 129Xe</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cleveland, Zackary I.; Möller, Harald E.; Hedlund, Laurence W.; Nouls, John C.; Freeman, Matthew S.; Qi, Yi; Driehuys, Bastiaan</p> <p>2012-01-01</p> <p>Background Hyperpolarized (HP) 129Xe magnetic resonance imaging (MRI) permits high resolution, regional visualization of pulmonary ventilation. Additionally, its reasonably high solubility (>10%) and large chemical shift range (>200 ppm) in tissues allow HP 129Xe to serve as a regional probe of pulmonary perfusion and <span class="hlt">gas</span> transport, when introduced directly into the vasculature. In earlier work, vascular delivery was accomplished in rats by first dissolving HP 129Xe in a biologically compatible carrier solution, injecting the solution into the vasculature, and then detecting HP 129Xe as it emerged into the alveolar airspaces. Although easily implemented, this approach was constrained by the tolerable injection volume and the duration of the HP 129Xe signal. Methods and Principal Findings Here, we overcome the volume and temporal constraints imposed by injection, by using hydrophobic, microporous, <span class="hlt">gas-exchange</span> membranes to directly and continuously infuse 129Xe into the arterial blood of live rats with an extracorporeal (EC) circuit. The resulting <span class="hlt">gas</span>-phase 129Xe signal is sufficient to generate diffusive <span class="hlt">gas</span> <span class="hlt">exchange</span>- and pulmonary perfusion-dependent, 3D MR images with a nominal resolution of 2×2×2 mm3. We also show that the 129Xe signal dynamics during EC infusion are well described by an analytical model that incorporates both mass transport into the blood and longitudinal relaxation. Conclusions Extracorporeal infusion of HP 129Xe enables rapid, 3D MR imaging of rat lungs and, when combined with ventilation imaging, will permit spatially resolved studies of the ventilation-perfusion ratio in small animals. Moreover, EC infusion should allow 129Xe to be delivered elsewhere in the body and make possible functional and molecular imaging approaches that are currently not feasible using inhaled HP 129Xe. PMID:22363613</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JASMS..23...57K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JASMS..23...57K"><span>Solution and <span class="hlt">Gas</span>-Phase H/D <span class="hlt">Exchange</span> of Protein-Small-Molecule Complexes: Cex and Its Inhibitors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kang, Yang; Terrier, Peran; Ding, Chuanfan; Douglas, D. J.</p> <p>2012-01-01</p> <p>The properties of noncovalent complexes of the enzyme exo-1,4-β-D-glycanase ("Cex") with three aza-sugar inhibitors, deoxynojirimycin (X2DNJ), isofagomine lactam (X2IL), and isofagomine (X2IF), have been studied with solution and <span class="hlt">gas</span>-phase hydrogen deuterium <span class="hlt">exchange</span> (H/Dx) and measurements of collision cross sections of <span class="hlt">gas</span>-phase ions. In solution, complexes have lower H/Dx levels than free Cex because binding the inhibitors blocks some sites from H/Dx and reduces fluctuations of the protein. In mass spectra of complexes, abundant Cex ions are seen, which mostly are formed by dissociation of complexes in the ion sampling interface. Both complex ions and Cex ions formed from a solution containing complexes have lower cross sections than Cex ions from a solution of Cex alone. This suggests the Cex ions formed by dissociation "remember" their solution conformations. For a given charge, ions of the complexes have greater <span class="hlt">gas</span>-phase H/Dx levels than ions of Cex. Unlike cross sections, H/Dx levels of the complexes do not correlate with the relative <span class="hlt">gas</span>-phase binding strengths measured by MS/MS. Cex ions from solutions with or without inhibitors, which have different cross sections, show the same H/Dx level after 15 s, indicating the ions may fold or unfold on the seconds time scale of the H/Dx experiment. Thus, cross sections show that complexes have more compact conformations than free protein ions on the time scale of ca. 1 ms. The <span class="hlt">gas</span>-phase H/Dx measurements show that at least some complexes retain different conformations from the Cex ions on a time scale of seconds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6039646-process-gas-hear-recovery','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6039646-process-gas-hear-recovery"><span>Process <span class="hlt">gas</span> hear recovery</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Anderson, W.M.; Thurner, R.P.</p> <p>1977-01-01</p> <p>In considering the use of regenerative and recuperative heat <span class="hlt">exchangers</span> for process-<span class="hlt">gas</span> heat recovery general information regarding heat-<span class="hlt">exchanger</span> effectiveness versus initial capital investment and operating costs is discussed. Specific examples for preheating combustion air for process furnaces and for using primary and secondary heat <span class="hlt">exchangers</span> in conjunction with an air-pollution-control system for drying and curing ovens cover basic heat-<span class="hlt">exchanger</span> design and application considerations as well as investment-payback factors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25743409','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25743409"><span>Estimation of air-water <span class="hlt">gas</span> <span class="hlt">exchange</span> coefficient in a shallow lagoon based on 222Rn mass balance.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cockenpot, S; Claude, C; Radakovitch, O</p> <p>2015-05-01</p> <p>The radon-222 mass balance is now commonly used to quantify water fluxes due to Submarine Groundwater Discharge (SGD) in coastal areas. One of the main loss terms of this mass balance, the radon evasion to the atmosphere, is based on empirical equations. This term is generally estimated using one among the many empirical equations describing the <span class="hlt">gas</span> transfer velocity as a function of wind speed that have been proposed in the literature. These equations were, however, mainly obtained from areas of deep water and may be less appropriate for shallow areas. Here, we calculate the radon mass balance for a windy shallow coastal lagoon (mean depth of 6m and surface area of 1.55*10(8) m(2)) and use these data to estimate the radon loss to the atmosphere and the corresponding <span class="hlt">gas</span> transfer velocity. We present new equations, adapted to our shallow water body, to express the <span class="hlt">gas</span> transfer velocity as a function of wind speed at 10 m height (wind range from 2 to 12.5 m/s). When compared with those from the literature, these equations fit particularly well with the one of Kremer et al. (2003). Finally, we emphasize that some <span class="hlt">gas</span> transfer <span class="hlt">exchange</span> may always occur, even for conditions without wind. Copyright © 2015 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28192496','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28192496"><span>Impact of nitrogen fertilization on soil-Atmosphere greenhouse <span class="hlt">gas</span> <span class="hlt">exchanges</span> in eucalypt plantations with different soil characteristics in southern China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Kai; Zheng, Hua; Chen, Falin; Li, Ruida; Yang, Miao; Ouyang, Zhiyun; Lan, Jun; Xiang, Xuewu</p> <p>2017-01-01</p> <p>Nitrogen (N) fertilization is necessary to sustain productivity in eucalypt plantations, but it can increase the risk of greenhouse <span class="hlt">gas</span> emissions. However, the response of soil greenhouse <span class="hlt">gas</span> emissions to N fertilization might be influenced by soil characteristics, which is of great significance for accurately assessing greenhouse <span class="hlt">gas</span> budgets and scientific fertilization in plantations. We conducted a two-year N fertilization experiment (control [CK], low N [LN], middle N [MN] and high N [HN] fertilization) in two eucalypt plantations with different soil characteristics (higher and lower soil organic carbon sites [HSOC and LSOC]) in Guangxi, China, and assessed soil-atmosphere greenhouse <span class="hlt">gas</span> <span class="hlt">exchanges</span>. The annual mean fluxes of soil CO2, CH4, and N2O were separately 153-266 mg m-2 h-1, -55 --40 μg m-2 h-1, and 11-95 μg m-2 h-1, with CO2 and N2O emissions showing significant seasonal variations. N fertilization significantly increased soil CO2 and N2O emissions and decreased CH4 uptake at both sites. There were significant interactions of N fertilization and SOC level on soil CO2 and N2O emissions. At the LSOC site, the annual mean flux of soil CO2 emission was only significantly higher than the CK treatment in the HN treatment, but, at the HSOC site, the annual mean flux of soil CO2 emission was significantly higher for both the LN (or MN) and HN treatments in comparison to the CK treatment. Under the CK and LN treatments, the annual mean flux of N2O emission was not significantly different between HSOC and LSOC sites, but under the HN treatment, it was significantly higher in the HSOC site than in the LSOC site. Correlation analysis showed that changes in soil CO2 and N2O emissions were significantly related to soil dissolved organic carbon, ammonia, nitrate and pH. Our results suggested significant interactions of N fertilization and soil characteristics existed in soil-atmosphere greenhouse <span class="hlt">gas</span> <span class="hlt">exchanges</span>, which should be considered in assessing greenhouse <span class="hlt">gas</span></p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5305064','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5305064"><span>Impact of nitrogen fertilization on soil–Atmosphere greenhouse <span class="hlt">gas</span> <span class="hlt">exchanges</span> in eucalypt plantations with different soil characteristics in southern China</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zhang, Kai; Zheng, Hua; Chen, Falin; Li, Ruida; Yang, Miao; Ouyang, Zhiyun; Lan, Jun; Xiang, Xuewu</p> <p>2017-01-01</p> <p>Nitrogen (N) fertilization is necessary to sustain productivity in eucalypt plantations, but it can increase the risk of greenhouse <span class="hlt">gas</span> emissions. However, the response of soil greenhouse <span class="hlt">gas</span> emissions to N fertilization might be influenced by soil characteristics, which is of great significance for accurately assessing greenhouse <span class="hlt">gas</span> budgets and scientific fertilization in plantations. We conducted a two-year N fertilization experiment (control [CK], low N [LN], middle N [MN] and high N [HN] fertilization) in two eucalypt plantations with different soil characteristics (higher and lower soil organic carbon sites [HSOC and LSOC]) in Guangxi, China, and assessed soil–atmosphere greenhouse <span class="hlt">gas</span> <span class="hlt">exchanges</span>. The annual mean fluxes of soil CO2, CH4, and N2O were separately 153–266 mg m-2 h-1, -55 –-40 μg m-2 h-1, and 11–95 μg m-2 h-1, with CO2 and N2O emissions showing significant seasonal variations. N fertilization significantly increased soil CO2 and N2O emissions and decreased CH4 uptake at both sites. There were significant interactions of N fertilization and SOC level on soil CO2 and N2O emissions. At the LSOC site, the annual mean flux of soil CO2 emission was only significantly higher than the CK treatment in the HN treatment, but, at the HSOC site, the annual mean flux of soil CO2 emission was significantly higher for both the LN (or MN) and HN treatments in comparison to the CK treatment. Under the CK and LN treatments, the annual mean flux of N2O emission was not significantly different between HSOC and LSOC sites, but under the HN treatment, it was significantly higher in the HSOC site than in the LSOC site. Correlation analysis showed that changes in soil CO2 and N2O emissions were significantly related to soil dissolved organic carbon, ammonia, nitrate and pH. Our results suggested significant interactions of N fertilization and soil characteristics existed in soil–atmosphere greenhouse <span class="hlt">gas</span> <span class="hlt">exchanges</span>, which should be considered in assessing</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15683168','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15683168"><span>Air-water <span class="hlt">gas</span> <span class="hlt">exchange</span> of chlorinated pesticides in four lakes spanning a 1,205 meter elevation range in the Canadian Rocky Mountains.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wilkinson, Andrew C; Kimpe, Lynda E; Blais, Jules M</p> <p>2005-01-01</p> <p>Concentrations of selected persistent organic pollutants (POPs) in air and water were measured from four lakes that transect the Canadian Rocky Mountains. These data were used in combination with wind velocity and temperature-adjusted Henry's law constants to estimate the direction and magnitude of chemical <span class="hlt">exchange</span> across the air-water interface of these lakes. Bow Lake (1,975 m above sea level [masl]) was studied during the summers of 1998 through 2000; Donald (770 masl) was studied during the summer of 1999; Dixon Dam Lake (946 masl) and Kananaskis Lake (1,667 masl) were studied during the summer of 2000. Hexachlorobenzene (HCB) and dieldrin volatilized from Bow Lake in spring and summer of 1998 to 2000 at a rate of 0.92 +/-1.1 and 0.55+/-0.37 ng m(-2) d(-1), respectively. The alpha-endosulfan deposited to Bow Lake at a rate of 3.4+/-2.2 ng m(-2) d(-1). Direction of <span class="hlt">gas</span> <span class="hlt">exchange</span> for gamma-hexachlorocyclohexane (gamma-HCH) changed from net deposition in 1998 to net volatilization in 1999, partly because of a surge in y-HCH concentrations in the water at Bow Lake in 1999. Average gamma-HCH concentrations in air declined steadily over the three-year period, from 0.021 ng m(-3) in 1998, to 0.0023 ng m(-3) in 2000, and to volatilization in 1999 and 2000. Neither the concentrations of organochlorine compounds (OCs) in air and water, nor the direction and rate of air-water <span class="hlt">gas</span> <span class="hlt">exchange</span> correlate with temperature or elevation. In general, losses of pesticides by outflow were greater than the amount <span class="hlt">exchanged</span> across the air-water interface in these lakes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1030994','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1030994"><span>Integrated Heat <span class="hlt">Exchange</span> For Recuperation In <span class="hlt">Gas</span> Turbine Engines</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2016-12-01</p> <p><span class="hlt">exchange</span> system within the engine using existing blade surfaces to extract and insert heat. Due to the highly turbulent and transient flow, heat...transfer coefficients in turbomachinery are extremely high, making this possible. Heat transfer between the turbine and compressor blade surfaces could be...<span class="hlt">exchange</span> system within the engine using existing blade surfaces to extract and insert heat. Due to the highly turbulent and transient flow, heat transfer</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007GBioC..21.2015S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007GBioC..21.2015S"><span>Constraining global air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> for CO2 with recent bomb 14C measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sweeney, Colm; Gloor, Emanuel; Jacobson, Andrew R.; Key, Robert M.; McKinley, Galen; Sarmiento, Jorge L.; Wanninkhof, Rik</p> <p>2007-06-01</p> <p>The 14CO2 released into the stratosphere during bomb testing in the early 1960s provides a global constraint on air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> of soluble atmospheric gases like CO2. Using the most complete database of dissolved inorganic radiocarbon, DI14C, available to date and a suite of ocean general circulation models in an inverse mode we recalculate the ocean inventory of bomb-produced DI14C in the global ocean and confirm that there is a 25% decrease from previous estimates using older DI14C data sets. Additionally, we find a 33% lower globally averaged <span class="hlt">gas</span> transfer velocity for CO2 compared to previous estimates (Wanninkhof, 1992) using the NCEP/NCAR Reanalysis 1 1954-2000 where the global mean winds are 6.9 m s-1. Unlike some earlier ocean radiocarbon studies, the implied <span class="hlt">gas</span> transfer velocity finally closes the gap between small-scale deliberate tracer studies and global-scale estimates. Additionally, the total inventory of bomb-produced radiocarbon in the ocean is now in agreement with global budgets based on radiocarbon measurements made in the stratosphere and troposphere. Using the implied relationship between wind speed and <span class="hlt">gas</span> transfer velocity ks = 0.27<u102>(Sc/660)-0.5 and standard partial pressure difference climatology of CO2 we obtain an net air-sea flux estimate of 1.3 ± 0.5 PgCyr-1 for 1995. After accounting for the carbon transferred from rivers to the deep ocean, our estimate of oceanic uptake (1.8 ± 0.5 PgCyr-1) compares well with estimates based on ocean inventories, ocean transport inversions using ocean concentration data, and model simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18245633','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18245633"><span>The hygric hypothesis does not hold water: abolition of discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> cycles does not affect water loss in the ant Camponotus vicinus.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lighton, John R B; Turner, Robbin J</p> <p>2008-02-01</p> <p>The discontinuous <span class="hlt">gas</span> <span class="hlt">exchange</span> cycle (DGC) of insects and other tracheate arthropods temporally decouples oxygen uptake and carbon dioxide emission and generates powerful concentration gradients for both <span class="hlt">gas</span> species between the outside world and the tracheal system. Although the DGC is considered an adaptation to reduce respiratory water loss (RWL) - the "hygric hypothesis" - it is absent from many taxa, including xeric ones. The "chthonic hypothesis" states that the DGC originated as an adaptation to <span class="hlt">gas</span> <span class="hlt">exchange</span> in hypoxic and hypercapnic, i.e. underground, environments. If that is the case then the DGC is not the ancestral condition, and its expression is not necessarily a requirement for reducing RWL. Here we report a study of water loss rate in the ant Camponotus vicinus, measured while its DGC was slowly eliminated by gradual hypoxia (hypoxic ramp de-DGCing). Metabolic rate remained constant. The DGC ceased at a mean P(O2) of 8.4 kPa. RWL in the absence of DGCs was not affected until P(O2) declined below 3.9 kPa. Below that value, non-DGC spiracular regulation failed, accompanied by a large increase in RWL. Thus, the spiracular control strategy of the DGC is not required for low RWL, even in animals that normally express the DGC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70013126','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70013126"><span>CONCEPTUAL MODEL FOR ORIGIN OF <span class="hlt">ABNORMALLY</span> PRESSURED <span class="hlt">GAS</span> ACCUMULATIONS IN LOW-PERMEABILITY RESERVOIRS.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Law, B.E.; Dickinson, W.W.</p> <p>1985-01-01</p> <p>The paper suggests that overpressured and underpressured <span class="hlt">gas</span> accumulations of this type have a common origin. In basins containing overpressured <span class="hlt">gas</span> accumulations, rates of thermogenic <span class="hlt">gas</span> accumulation exceed <span class="hlt">gas</span> loss, causing fluid (<span class="hlt">gas</span>) pressure to rise above the regional hydrostatic pressure. Free water in the larger pores is forced out of the <span class="hlt">gas</span> generation zone into overlying and updip, normally pressured, water-bearing rocks. While other diagenetic processes continue, a pore network with very low permeability develops. As a result, <span class="hlt">gas</span> accumulates in these low-permeability reservoirs at rates higher than it is lost. In basins containing underpressured <span class="hlt">gas</span> accumulations, rates of <span class="hlt">gas</span> generation and accumulation are less than <span class="hlt">gas</span> loss. The basin-center <span class="hlt">gas</span> accumulation persists, but because of changes in the basin dynamics, the overpressured accumulation evolves into an underpressured system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AIPC.1608..163M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AIPC.1608..163M"><span>The heat <span class="hlt">exchanger</span> of small pellet boiler for phytomass</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mičieta, Jozef; Lenhard, Richard; Jandačka, Jozef</p> <p>2014-08-01</p> <p>Combustion of pellets from plant biomass (phytomass) causes various troubles. Main problem is slagging ash because of low melting temperature of ash from phytomass. This problem is possible to solve either improving energetic properties of phytomass by additives or modification of boiler construction. A small-scale boiler for phytomass is different in construction of heat <span class="hlt">exchanger</span> and furnace mainly. We solve major problem - slagging ash, by decreasing combustion temperature via redesign of pellet burner and boiler body. Consequence of lower combustion temperature is also lower temperature gradient of combustion <span class="hlt">gas</span>. It means that is necessary to design larger heat <span class="hlt">exchanging</span> surface. We plane to use underfed burner, so we would utilize circle symmetry heat <span class="hlt">exchanger</span>. Paper deals design of heat <span class="hlt">exchanger</span> construction with help of CFD simulation. Our purpose is to keep uniform water flux and combustion <span class="hlt">gas</span> flux in heat <span class="hlt">exchanger</span> without zone of local overheating and excess cooling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23418521','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23418521"><span>Effect of surfactant and partial liquid ventilation treatment on <span class="hlt">gas</span> <span class="hlt">exchange</span> and lung mechanics in immature lambs: influence of gestational age.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rey-Santano, Carmen; Mielgo, Victoria; Gastiasoro, Elena; Valls-i-Soler, Adolfo; Murgia, Xabier</p> <p>2013-01-01</p> <p>Surfactant (SF) and partial liquid ventilation (PLV) improve <span class="hlt">gas</span> <span class="hlt">exchange</span> and lung mechanics in neonatal RDS. However, variations in the effects of SF and PLV with degree of lung immaturity have not been thoroughly explored. Experimental Neonatal Respiratory Physiology Research Unit, Cruces University Hospital. Prospective, randomized study using sealed envelopes. 36 preterm lambs were exposed (at 125 or 133-days of gestational age) by laparotomy and intubated. Catheters were placed in the jugular vein and carotid artery. All the lambs were assigned to one of three subgroups given: 20 mL/Kg perfluorocarbon and managed with partial liquid ventilation (PLV), surfactant (Curosurf®, 200 mg/kg) or (3) no pulmonary treatment (Controls) for 3 h. Cardiovascular parameters, blood gases and pulmonary mechanics were measured. In 125-day gestation lambs, SF treatment partially improved <span class="hlt">gas</span> <span class="hlt">exchange</span> and lung mechanics, while PLV produced significant rapid improvements in these parameters. In 133-day lambs, treatments with SF or PLV achieved similarly good responses. Neither surfactant nor PLV significantly affected the cardiovascular parameters. SF therapy response was more effective in the older gestational age group whereas the effectiveness of PLV therapy was not gestational age dependent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=269583','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=269583"><span>Ambient ozone effects on <span class="hlt">gas</span> <span class="hlt">exchange</span> and total non-structural carbohydrate levels in cutleaf coneflower (Rudbeckia laciniata L.) growing in Great Smoky Mountains National Park</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Ozone-sensitive and -tolerant individuals of the perennial herbaceous cutleaf coneflower (Rudbeckia laciniata L.) were compared for their <span class="hlt">gas</span> <span class="hlt">exchange</span> characteristics and total non-structural carbohydrates in the Great Smoky Mountains National Park USA. Net photosynthesis decreased with increased f...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/20942912-gas-exchange-patterns-mediterranean-fruit-fly-pupae-diptera-tephritidae-tool-forecast-developmental-stage','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/20942912-gas-exchange-patterns-mediterranean-fruit-fly-pupae-diptera-tephritidae-tool-forecast-developmental-stage"><span><span class="hlt">Gas-exchange</span> patterns of Mediterranean fruit fly Pupae (Diptera: Tephritidae): A tool to forecast developmental stage</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Nestel, D.; Nemny-Lavy, E.; Alchanatis, V.</p> <p></p> <p>The pattern of <span class="hlt">gas-exchange</span> (CO{sub 2} emission) was investigated for developing Mediterranean fruit fly (medfly) Ceratitis capitata (Wiedemann) pupae incubated at different temperatures. This study was undertaken to explore the usefulness of <span class="hlt">gas-exchange</span> systems in the determination of physiological age in developing pupae that are mass produced for sterile insect technique projects. The rate of CO{sub 2} emission was measured in a closed flow-through system connected to commercial infrared <span class="hlt">gas</span> analysis equipment. Metabolic activity (rate of CO{sub 2} emission) was related to pupal eye-color, which is the current technique used to determine physiological age. Eye-color was characterized digitally with 3more » variables (Hue, Saturation and Intensity), and color separated by discriminant analysis. The rate of CO{sub 2} emission throughout pupal development followed a U-shape, with high levels of emission during pupariation, pupal transformation and final pharate adult stages. Temperature affected the development time of pupae, but not the basic CO{sub 2} emission patterns during development. In all temperatures, rates of CO{sub 2} emission 1 and 2 d before adult emergence were very similar. After mid larval-adult transition (e.g., phanerocephalic pupa), digital eye-color was significantly correlated with CO{sub 2} emission. Results support the suggestion that <span class="hlt">gas-exchange</span> should be explored further as a system to determine pupal physiological age in mass production of fruit flies. (author) [Spanish] En el presente estudio se investigaron los patrones de intercambio gaseoso (emision de CO{sub 2}) en pupas de la mosca de las frutas del Mediterraneo (Ceratitis capitata Wiedemann) incubadas a diferentes temperaturas. El estudio fue realizado con la finalidad de explorar la utilizacion de sistemas de intercambio gaseoso en la determinacion de la edad fisiologica de pupas durante su produccion masiva en proyectos de mosca esteril. La proporcion de emision de CO{sub 2</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPS...342..393I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPS...342..393I"><span>Application of a self-supporting microporous layer to <span class="hlt">gas</span> diffusion layers of proton <span class="hlt">exchange</span> membrane fuel cells</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ito, Hiroshi; Heo, Yun; Ishida, Masayoshi; Nakano, Akihiro; Someya, Satoshi; Munakata, Tetsuo</p> <p>2017-02-01</p> <p>The intrinsic effect of properties of a self-supporting microporous layer (MPL) on the performance of proton <span class="hlt">exchange</span> membrane fuel cells (PEMFCs) is identified. First, a self-supporting MPL is fabricated and applied to a <span class="hlt">gas</span> diffusion layer (GDL) of a PEMFC, when the GDL is either an integrated sample composed of a <span class="hlt">gas</span> diffusion backing (GDB, i.e., carbon paper) combined with MPL or a sample with only MPL. Cell performance tests reveal that, the same as the MPL fabricated by the coating method, the self-supporting MPL on the GDB improves the cell performance at high current density. Furthermore, the GDL composed only of the MPL (i.e., GDB-free GDL) shows better performance than does the integrated GDB/MPL GDL. These results along with literature data strongly suggest that the low thermal conductivity of MPL induces a high temperature throughout the GDL, and thus vapor diffusion is dominant in the transport of product water through the MPL.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1253369','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1253369"><span>Internal <span class="hlt">gas</span> and liquid distributor for electrodeionization device</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Lin, YuPo J.; Snyder, Seth W.; Henry, Michael P.; Datta, Saurav</p> <p>2016-05-17</p> <p>The present invention provides a resin-wafer electrodeionization (RW-EDI) apparatus including cathode and anode electrodes separated by a plurality of porous solid ion <span class="hlt">exchange</span> resin wafers, which when in use are filled with an aqueous fluid. The apparatus includes one or more wafers comprising a basic ion <span class="hlt">exchange</span> medium, and preferably includes one or more wafers comprising an acidic ion <span class="hlt">exchange</span> medium. The wafers are separated from one another by ion <span class="hlt">exchange</span> membranes. The <span class="hlt">gas</span> and aqueous fluid are introduced into each basic wafer via a porous <span class="hlt">gas</span> distributor which disperses the <span class="hlt">gas</span> as micro-sized bubbles laterally throughout the distributor before entering the wafer. The fluid within the acidic and/or basic ion <span class="hlt">exchange</span> wafers preferably includes, or is in contact with, a carbonic anhydrase (CA) enzyme or inorganic catalyst to facilitate conversion of bicarbonate ion to carbon dioxide within the acidic medium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17669753','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17669753"><span>Seasonal patterns of cytokinins and microclimate and the mediation of <span class="hlt">gas</span> <span class="hlt">exchange</span> among canopy layers of mature Acer saccharum trees.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Reeves, Ian; Emery, R J Neil</p> <p>2007-11-01</p> <p>Seasonal patterns of cytokinins (CKs) and microclimate were examined in the upper, middle and lower canopy layers of mature Acer saccharum Marsh. (sugar maple) trees to elucidate the potential role of CKs in the mediation of <span class="hlt">gas</span> <span class="hlt">exchange</span>. The upper canopy showed a distinctly dissimilar microclimate from the middle and lower canopy layers with higher photosynthetically active radiation and wind speed, but showed no corresponding differences in transpiration (E) or stomatal conductance (g(s)). Although E and g(s) tended to be higher in the upper canopy than in the middle and lower canopies, the differences were not significant, indicating regulation beyond the passive response to changes in microclimate. The upper canopy accumulated significantly higher concentrations of CKs, predominantly as ribosides, and all canopy layers showed distinct seasonal patterns in CK profiles. Multiple regression models showed significant relationships between both g(s) and E and foliar CK concentration, although these relationships varied among canopy layers. The relationships were strongest in the middle and lower canopy layers where there was less fluctuation in leaf water status and less variability in abiotic variables. The relationships between <span class="hlt">gas</span> <span class="hlt">exchange</span> parameters and leaf CK concentration began to decouple near the end of the growing season as foliar phytohormone concentrations changed with the approach of dormancy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/862648','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/862648"><span>Process for hydrogen isotope concentration between liquid water and hydrogen <span class="hlt">gas</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Stevens, William H.</p> <p>1976-09-21</p> <p>A process for hydrogen isotope <span class="hlt">exchange</span> and concentration between liquid water and hydrogen <span class="hlt">gas</span>, wherein liquid water and hydrogen <span class="hlt">gas</span> are contacted, in an <span class="hlt">exchange</span> section, with one another and with at least one catalyst body comprising at least one metal selected from Group VIII of the Periodic Table and preferably a support therefor, the catalyst body has a liquid-water-repellent, <span class="hlt">gas</span> permeable polymer or organic resin coating, preferably a fluorinated olefin polymer or silicone coating, so that the isotope concentration takes place by two simultaneously occurring steps, namely, ##EQU1## WHILE THE HYDROGEN <span class="hlt">GAS</span> FED TO THE <span class="hlt">EXCHANGE</span> SECTION IS DERIVED IN A REACTOR VESSEL FROM LIQUID WATER THAT HAS PASSED THROUGH THE <span class="hlt">EXCHANGE</span> SECTION.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23513655','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23513655"><span>Respiratory system. Part 2: Gaseous <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McLafferty, Ella; Johnstone, Carolyn; Hendry, Charles; Farley, Alistair</p> <p></p> <p>This article, which isthe last in the life sciences series and the second of two articles on the respiratory system, describes gaseous <span class="hlt">exchange</span> in the lungs, transport of oxygen and carbon dioxide, and internal and external respiration. The article concludes with a brief consideration of two conditions that affect <span class="hlt">gas</span> <span class="hlt">exchange</span> and transport: carbon monoxide poisoning and chronic obstructive pulmonary disease.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.H31G0704O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.H31G0704O"><span>Sensitivity of Photosynthetic <span class="hlt">Gas</span> <span class="hlt">Exchange</span> and Growth of Lodgepole Pine to Climate Variability Depends on the Age of Pleistocene Glacial Surfaces</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Osborn, B.; Chapple, W.; Ewers, B. E.; Williams, D. G.</p> <p>2014-12-01</p> <p>The interaction between soil conditions and climate variability plays a central role in the ecohydrological functions of montane conifer forests. Although soil moisture availability to trees is largely dependent on climate, the depth and texture of soil exerts a key secondary influence. Multiple Pleistocene glacial events have shaped the landscape of the central Rocky Mountains creating a patchwork of soils differing in age and textural classification. This mosaic of soil conditions impacts hydrological properties, and montane conifer forests potentially respond to climate variability quite differently depending on the age of glacial till and soil development. We hypothesized that the age of glacial till and associated soil textural changes exert strong control on growth and photosynthetic <span class="hlt">gas</span> <span class="hlt">exchange</span> of lodgepole pine. We examined physiological and growth responses of lodgepole pine to interannual variation in maximum annual snow water equivalence (SWEmax) of montane snowpack and growing season air temperature (Tair) and vapor pressure deficit (VPD) across a chronosequence of Pleistocene glacial tills ranging in age from 700k to 12k years. Soil textural differences across the glacial tills illustrate the varying degrees of weathering with the most well developed soils with highest clay content on the oldest till surfaces. We show that sensitivity of growth and carbon isotope discrimination, an integrated measure of canopy <span class="hlt">gas</span> <span class="hlt">exchange</span> properties, to interannual variation SWEmax , Tair and VPD is greatest on young till surfaces, whereas trees on old glacial tills with well-developed soils are mostly insensitive to these interannual climate fluctuations. Tree-ring widths were most sensitive to changes in SWEmax on young glacial tills (p < 0.01), and less sensitive on the oldest till (p < 0.05). Tair correlates strongly with δ13C values on the oldest and youngest tills sites, but shows no significant relationship on the middle aged glacial till. It is clear that</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26178701','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26178701"><span>Isotopic <span class="hlt">Exchange</span> in Porous and Dense Magnesium Borohydride.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zavorotynska, Olena; Deledda, Stefano; Li, Guanqiao; Matsuo, Motoaki; Orimo, Shin-ichi; Hauback, Bjørn C</p> <p>2015-09-01</p> <p>Magnesium borohydride (Mg(BH4)2) is one of the most promising complex hydrides presently studied for energy-related applications. Many of its properties depend on the stability of the BH4(-) anion. The BH4(-) stability was investigated with respect to H→D <span class="hlt">exchange</span>. In situ Raman measurements on high-surface-area porous Mg(BH4 )2 in 0.3 MPa D2 have shown that the isotopic <span class="hlt">exchange</span> at appreciable rates occurs already at 373 K. This is the lowest <span class="hlt">exchange</span> temperature observed in stable borohydrides. <span class="hlt">Gas</span>-solid isotopic <span class="hlt">exchange</span> follows the BH4(-) +D˙ →BH3D(-) +H˙ mechanism at least at the initial reaction steps. Ex situ deuteration of porous Mg(BH4)2 and its dense-phase polymorph indicates that the intrinsic porosity of the hydride is the key behind the high isotopic <span class="hlt">exchange</span> rates. It implies that the solid-state H(D) diffusion is considerably slower than the <span class="hlt">gas</span>-solid H→D <span class="hlt">exchange</span> reaction at the surface and it is a rate-limiting steps for hydrogen desorption and absorption in Mg(BH4)2. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26359720','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26359720"><span>Different Apparent <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Coefficients for CO2 and CH4: Comparing a Brown-Water and a Clear-Water Lake in the Boreal Zone during the Whole Growing Season.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rantakari, Miitta; Heiskanen, Jouni; Mammarella, Ivan; Tulonen, Tiina; Linnaluoma, Jessica; Kankaala, Paula; Ojala, Anne</p> <p>2015-10-06</p> <p>The air-water <span class="hlt">exchange</span> of carbon dioxide (CO2) and methane (CH4) is a central process during attempts to establish carbon budgets for lakes and landscapes containing lakes. Lake-atmosphere diffusive <span class="hlt">gas</span> <span class="hlt">exchange</span> is dependent on the concentration gradient between air and surface water and also on the <span class="hlt">gas</span> transfer velocity, often described with the <span class="hlt">gas</span> transfer coefficient k. We used the floating-chamber method in connection with surface water <span class="hlt">gas</span> concentration measurements to estimate the <span class="hlt">gas</span> transfer velocity of CO2 (kCO2) and CH4 (kCH4) weekly throughout the entire growing season in two contrasting boreal lakes, a humic oligotrophic lake and a clear-water productive lake, in order to investigate the earlier observed differences between kCO2 and kCH4. We found that the seasonally averaged <span class="hlt">gas</span> transfer velocity of CH4 was the same for both lakes. When the lakes were sources of CO2, the <span class="hlt">gas</span> transfer velocity of CO2 was also similar between the two study lakes. The <span class="hlt">gas</span> transfer velocity of CH4 was constantly higher than that of CO2 in both lakes, a result also found in other studies but for reasons not yet fully understood. We found no differences between the lakes, demonstrating that the difference between kCO2 and kCH4 is not dependent on season or the characteristics of the lake.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740010444','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740010444"><span>Light bulb heat <span class="hlt">exchanger</span> for magnetohydrodynamic generator applications - Preliminary evaluation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smith, J. M.; Hwang, C. C.; Seikel, G. R.</p> <p>1974-01-01</p> <p>The light-bulb heat-<span class="hlt">exchanger</span> concept is investigated as a possible means of using a combustion heat source to supply energy to an inert <span class="hlt">gas</span> MHD power generator system. In this concept, combustion gases flow through a central passage which consists of a duct with transparent walls through which heat is transferred by radiation to a radiation receiver which in turn heats the inert <span class="hlt">gas</span> by convection. The effects of combustion-<span class="hlt">gas</span> emissivity, transparent-wall-transmissivity, radiation-receiver emissivity, and the use of fins in the inert <span class="hlt">gas</span> coolant passage are studied. The results indicate that inert <span class="hlt">gas</span> outlet temperatures of 2500 K are possible for combustion temperatures of 3200 K and that sufficient energy can be transferred from the combustion <span class="hlt">gas</span> to reduce its temperature to approximately 2000 K. At this temperature more conventional heat <span class="hlt">exchangers</span> can be used.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C11A0352L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C11A0352L"><span>Radon and radium in the ice-covered Arctic Ocean, and what they reveal about <span class="hlt">gas</span> <span class="hlt">exchange</span> in the sea ice zone.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Loose, B.; Kelly, R. P.; Bigdeli, A.; Moran, S. B.</p> <p>2014-12-01</p> <p>The polar sea ice zones are regions of high primary productivity and interior water mass formation. Consequently, the seasonal sea ice cycle appears important to both the solubility and biological carbon pumps. To estimate net CO2 transfer in the sea ice zone, we require accurate estimates of the air-sea <span class="hlt">gas</span> transfer velocity. In the open ocean, the <span class="hlt">gas</span> transfer velocity is driven by wind, waves and bubbles - all of which are strongly altered by the presence of sea ice, making it difficult to translate open ocean estimates of <span class="hlt">gas</span> transfer to the ice zone. In this study, we present profiles of 222Rn and 226Ra throughout the mixed-layer and euphotic zone. Profiles were collected spanning a range of sea ice cover conditions from 40 to 100%. The profiles of Rn/Ra can be used to estimate the <span class="hlt">gas</span> transfer velocity, but the 3.8 day half-life of 222Rn implies that mixed layer radon will have a memory of the past ~20 days of <span class="hlt">gas</span> <span class="hlt">exchange</span> forcing, which may include a range of sea ice cover conditions. Here, we compare individual estimates of the <span class="hlt">gas</span> transfer velocity to the turbulent forcing conditions constrained from shipboard and regional reanalysis data to more appropriately capture the time history upper ocean Rn/Ra.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12415445','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12415445"><span>Comparison of the effects of heat and moisture <span class="hlt">exchangers</span> and heated humidifiers on ventilation and <span class="hlt">gas</span> <span class="hlt">exchange</span> during non-invasive ventilation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jaber, Samir; Chanques, Gérald; Matecki, Stefan; Ramonatxo, Michèle; Souche, Bruno; Perrigault, Pierre-François; Eledjam, Jean-Jacques</p> <p>2002-11-01</p> <p>To compare the short-term effects of a heat and moisture <span class="hlt">exchanger</span> (HME) and a heated humidifier (HH) during non-invasive ventilation (NIV). Prospective, clinical investigation. Intensive care unit of a university hospital. Twenty-four patients with acute respiratory failure (ARF). Each patient was studied with a HME and a HH in a random order during two consecutive 20min periods of NIV. Respiratory rate (RR), expiratory tidal volume (VTe) and expiratory minute ventilation (VE) were measured during the last 5 min of each period and blood gases were measured. Mean pressure support and positive end-expiratory pressure levels were, respectively, 15+/-4 and 6+/-2 cmH(2)O. VE was significantly greater with HME than with HH (14.8+/-4.8 vs 13.2+/-4.3 l/min; p<0.001). This increase in VE was the result of a greater RR for HME than for HH (26.5+/-10.6 vs 24.1+/-9.8 breaths/min; p=0.002), whereas the VT for HME was similar to that for HH (674+/-156 vs 643+/-148 ml; p=0.09). Arterial partial pressure of carbon dioxide (PaCO(2)) was significantly higher with a HME than with a HH (43.4+/-8.9 vs 40.8+/-8.2 mmHg; p<0.005), without significantly changing oxygenation. During NIV the increased dead space of a HME can negatively affect ventilatory function and <span class="hlt">gas</span> <span class="hlt">exchange</span>. The effect of HME dead space may decrease efficiency of NIV in patients with ARF.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16435279','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16435279"><span>The "Kluge-Lüttge Kammer": a preliminary evaluation of an enclosed, Crassulacean acid metabolism (CAM) Mesocosm that allows separation of synchronized and desynchronized contributions of plants to whole system <span class="hlt">gas</span> <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rascher, U; Bobich, E G; Osmond, C B</p> <p>2006-01-01</p> <p>Crassulacean acid metabolism (CAM) is recognized as a photosynthetic adaptation of plants to arid habitats. This paper presents a proof-of-concept evaluation of partitioning net CO2 <span class="hlt">exchanges</span> for soil and plants in an arid, exclusively CAM mesocosm, with soil depth and succulent plant biomass approximating that of natural Sonoran Desert ecosystems. We present the first evidence that an enclosed CAM-dominated soil and plant community exposed to a substantial day/night temperature difference (30/20 degrees C), exhibits a diel <span class="hlt">gas</span> <span class="hlt">exchange</span> pattern consisting of four consecutive phases with a distinct nocturnal CO2 uptake. These phases were modulated by plant assimilation and soil respiration processes. Day-time stomatal closure of the CAM cycle during phase III was used to eliminate aboveground photosynthetic assimilation and respiration and thereby to estimate belowground plant plus soil respiration. Rapid changes in temperature appeared to synchronize single plant <span class="hlt">gas</span> <span class="hlt">exchange</span> but individual plant <span class="hlt">gas</span> <span class="hlt">exchange</span> patterns were desynchronized at constant day/night temperatures (25 degrees C), masking the distinct mesocosm pattern. Overall, the mean carbon budget of this CAM model Sonoran Desert system was negative, releasing an average of 22.5 mmol CO2 m-2 d-1. The capacity for nocturnal CO2 assimilation in this exclusively CAM mesocosm was inadequate to recycle CO2 released by plant and soil respiration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/20632883-single-channel-testing-characterization-direct-gas-cooled-reactor-safe-heat-exchanger','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/20632883-single-channel-testing-characterization-direct-gas-cooled-reactor-safe-heat-exchanger"><span>Single Channel Testing for Characterization of the Direct <span class="hlt">Gas</span> Cooled Reactor and the SAFE-100 Heat <span class="hlt">Exchanger</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Bragg-Sitton, S.M.; Propulsion Research Center, NASA Marshall Space Flight Center, Huntsville, AL 35812; Kapernick, R.</p> <p>2004-02-04</p> <p>Experiments have been designed to characterize the coolant <span class="hlt">gas</span> flow in two space reactor concepts that are currently under investigation by NASA Marshall Space Flight Center and Los Alamos National Laboratory: the direct-drive <span class="hlt">gas</span>-cooled reactor (DDG) and the SAFE-100 heatpipe-cooled reactor (HPR). For the DDG concept, initial tests have been completed to measure pressure drop versus flow rate for a prototypic core flow channel, with <span class="hlt">gas</span> exiting to atmospheric pressure conditions. The experimental results of the completed DDG tests presented in this paper validate the predicted results to within a reasonable margin of error. These tests have resulted in amore » re-design of the flow annulus to reduce the pressure drop. Subsequent tests will be conducted with the re-designed flow channel and with the outlet pressure held at 150 psi (1 MPa). Design of a similar test for a nominal flow channel in the HPR heat <span class="hlt">exchanger</span> (HPR-HX) has been completed and hardware is currently being assembled for testing this channel at 150 psi. When completed, these test programs will provide the data necessary to validate calculated flow performance for these reactor concepts (pressure drop and film temperature rise)« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16394688','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16394688"><span>Open and closed-circuit endotracheal suctioning in acute lung injury: efficiency and effects on <span class="hlt">gas</span> <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lasocki, Sigismond; Lu, Qin; Sartorius, Alfonso; Fouillat, Dominique; Remerand, Francis; Rouby, Jean-Jacques</p> <p>2006-01-01</p> <p>Closed-circuit endotracheal suctioning (CES) is advocated for preventing hypoxemia caused by the loss of lung volume resulting from open endotracheal suctioning (OES). However, the efficiency of CES and OES on tracheal secretion removal has never been compared in patients with acute lung injury. The authors designed a two-part study aimed at comparing <span class="hlt">gas</span> <span class="hlt">exchange</span> and efficiency between OES and CES performed at two levels of negative pressure. Among 18 patients with acute lung injury, 9 underwent CES and OES at 3-h intervals in a random order using a negative pressure of -200 mmHg. Nine other patients underwent CES twice using two levels of negative pressure (-200 and -400 mmHg) applied in a random order. After each CES, a recruitment maneuver was performed using 20 consecutive hyperinflations. Tracheal aspirates were weighed after each suctioning procedure. Arterial blood gases were continuously recorded using an intravascular sensor. Open endotracheal suctioning induced a significant 18% decrease in arterial oxygen tension (Pa(O2)) (range, +13 to -71%) and an 8% increase in arterial carbon dioxide tension (Pa(CO2)) (range, -2 to +16%) that persisted 15 min after the end of the procedure. CES using -200 cm H2O did not change Pa(O2), but tracheal aspirate mass was lower compared with OES (0.6 +/- 1.0 vs. 3.2 +/- 5.1 g; P = 0.03). Increasing negative pressure to -400 cm H2O during CES did not change Pa(O2) but increased the tracheal aspirate mass (1.7 +/- 1.6 vs. 1.0 +/- 1.3 g; P = 0.02). Closed-circuit endotracheal suctioning followed by a recruitment maneuver prevents hypoxemia resulting from OES but decreases secretion removal. Increasing suctioning pressure enhances suctioning efficiency without impairing <span class="hlt">gas</span> <span class="hlt">exchange</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4679436','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4679436"><span>MULTI-FREQUENCY OSCILLATORY VENTILATION IN THE PREMATURE LUNG: EFFECTS ON <span class="hlt">GAS</span> <span class="hlt">EXCHANGE</span>, MECHANICS, AND VENTILATION DISTRIBUTION</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kaczka, David W.; Herrmann, Jacob; Zonneveld, C. Elroy; Tingay, David G.; Lavizzari, Anna; Noble, Peter B.; Pillow, J. Jane</p> <p>2015-01-01</p> <p>Background Despite the theoretical benefits of high-frequency oscillatory ventilation (HFOV) in preterm infants, systematic reviews of randomized clinical trials do not confirm improved outcomes. We hypothesized that oscillating a premature lung with multiple frequencies simultaneously would improve <span class="hlt">gas</span> <span class="hlt">exchange</span> compared to traditional single-frequency oscillatory ventilation (SFOV). The goal of this study was to develop a novel method for HFOV, termed ‘multi-frequency oscillatory ventilation’ (MFOV), which relies on a broadband flow waveform more suitable for the heterogeneous mechanics of the immature lung. Methods Thirteen intubated preterm lambs were randomized to either SFOV or MFOV for 1 hour, followed by crossover to the alternative regimen for 1 hour. The SFOV waveform consisted of a pure sinusoidal flow at 5 Hz, while the customized MFOV waveform consisted of a 5 Hz fundamental with additional energy at 10 and 15 Hz. Per standardized protocol, mean pressure at airway opening (P̅ao) and inspired O2 fraction were adjusted as needed, and root mean square of the delivered oscillatory volume waveform (Vrms) was adjusted 15-minute intervals. A ventilatory cost function for SFOV and MFOV was defined as VC=(Vrms2PaCO2)Wt−1, where Wt denotes body weight. Results Averaged over all time points, MFOV resulted in significantly lower VC (246.9±6.0 vs. 363.5±15.9 mL2 mmHg kg−1) and P̅ao (12.8±0.3 vs. 14.1±0.5 cmH2O) compared to SFOV, suggesting more efficient <span class="hlt">gas</span> <span class="hlt">exchange</span> and enhanced lung recruitment at lower mean airway pressures. Conclusions Oscillation with simultaneous multiple frequencies may be a more efficient ventilator modality in premature lungs compared to traditional single-frequency HFOV. PMID:26495977</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17080613','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17080613"><span>Stem and leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and their responses to fire in a north Australian tropical savanna.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cernusak, Lucas A; Hutley, Lindsay B; Beringer, Jason; Tapper, Nigel J</p> <p>2006-04-01</p> <p>We measured stem CO2 efflux and leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> in a tropical savanna ecosystem in northern Australia, and assessed the impact of fire on these processes. <span class="hlt">Gas</span> <span class="hlt">exchange</span> of mature leaves that flushed after a fire showed only slight differences from that of mature leaves on unburned trees. Expanding leaves typically showed net losses of CO2 to the atmosphere in both burned and unburned trees, even under saturating irradiance. Fire caused stem CO2 efflux to decline in overstory trees, when measured 8 weeks post-fire. This decline was thought to have resulted from reduced availability of C substrate for respiration, due to reduced canopy photosynthesis caused by leaf scorching, and to priority allocation of fixed C towards reconstruction of a new canopy. At the ecosystem scale, we estimated the annual above-ground woody-tissue CO2 efflux to be 275 g C m(-2) ground area year(-1) in a non-fire year, or approximately 13% of the annual gross primary production. We contrasted the canopy physiology of two co-dominant overstory tree species, one of which has a smooth bark on its branches capable of photosynthetic re-fixation (Eucalyptus miniata), and the other of which has a thick, rough bark incapable of re-fixation (Eucalyptus tetrodonta). Eucalyptus miniata supported a larger branch sapwood cross-sectional area in the crown per unit subtending leaf area, and had higher leaf stomatal conductance and photosynthesis than E. tetrodonta. Re-fixation by photosynthetic bark reduces the C cost of delivering water to evaporative sites in leaves, because it reduces the net C cost of constructing and maintaining sapwood. We suggest that re-fixation allowed leaves of E. miniata to photosynthesize at higher rates than those of E. tetrodonta, while the two invested similar amounts of C in the maintenance of branch sapwood.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900054400&hterms=Cotton&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DCotton','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900054400&hterms=Cotton&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DCotton"><span>The relationship between leaf water status, <span class="hlt">gas</span> <span class="hlt">exchange</span>, and spectral reflectance in cotton leaves</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bowman, William D.</p> <p>1989-01-01</p> <p>Measurements of leaf spectral reflectance, the components of water potential, and leaf <span class="hlt">gas</span> <span class="hlt">exchanges</span> as a function of leaf water content were made to evaluate the use of NIR reflectance as an indicator of plant water status. Significant correlations were determined between spectral reflectance at 810 nm, 1665 nm, and 2210 nm and leaf relative water content, total water potential, and turgor pressure. However, the slopes of these relationships were relatively shallow and, when evaluated over the range of leaf water contents in which physiological activity occurs (e.g., photosynthesis), had lower r-squared values, and some relationships were not statistically significant. NIR reflectance varied primarily as a function of leaf water content, and not independently as a function of turgor pressure, which is a sensitive indicator of leaf water status. The limitations of this approach to measuring plant water stress are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013BGD....10.8415S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013BGD....10.8415S"><span>Biology and air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> controls on the distribution of carbon isotope ratios (δ13C) in the ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schmittner, A.; Gruber, N.; Mix, A. C.; Key, R. M.; Tagliabue, A.; Westberry, T. K.</p> <p>2013-05-01</p> <p>Analysis of observations and sensitivity experiments with a new three-dimensional global model of stable carbon isotope cycling elucidate the processes that control the distribution of δ13C in the contemporary and preindustrial ocean. Biological fractionation dominates the distribution of δ13CDIC of dissolved inorganic carbon (DIC) due to the sinking of isotopically light δ13C organic matter from the surface into the interior ocean. This process leads to low δ13CDIC values at dephs and in high latitude surface waters and high values in the upper ocean at low latitudes with maxima in the subtropics. Air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> provides an important secondary influence due to two effects. First, it acts to reduce the spatial gradients created by biology. Second, the associated temperature dependent fractionation tends to increase (decrease) δ13CDIC values of colder (warmer) water, which generates gradients that oppose those arising from biology. Our model results suggest that both effects are similarly important in influencing surface and interior δ13CDIC distributions. However, air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> is slow, so biological effect dominate spatial δ13CDIC gradients both in the interior and at the surface, in constrast to conclusions from some previous studies. Analysis of a new synthesis of δ13CDIC measurements from years 1990 to 2005 is used to quantify preformed (δ13Cpre) and remineralized (δ13Crem) contributions as well as the effects of biology (Δδ13Cbio) and air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> (δ13C*). The model reproduces major features of the observed large-scale distribution of δ13CDIC, δ13Cpre, δ13Crem, δ13C*, and Δδ13Cbio. Residual misfits are documented and analyzed. Simulated surface and subsurface δ13CDIC are influenced by details of the ecosystem model formulation. For example, inclusion of a simple parameterization of iron limitation of phytoplankton growth rates and temperature-dependent zooplankton grazing rates improves the agreement with δ13CDIC</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28436421','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28436421"><span><span class="hlt">Abnormal</span> <span class="hlt">gas</span>-liquid-solid phase transition behaviour of water observed with in situ environmental SEM.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chen, Xin; Shu, Jiapei; Chen, Qing</p> <p>2017-04-24</p> <p><span class="hlt">Gas</span>-liquid-solid phase transition behaviour of water is studied with environmental scanning electron microscopy for the first time. <span class="hlt">Abnormal</span> phenomena are observed. At a fixed pressure of 450 Pa, with the temperature set to -7 °C, direct desublimation happens, and ice grows continuously along the substrate surface. At 550 Pa, although ice is the stable phase according to the phase diagram, metastable liquid droplets first nucleate and grow to ~100-200 μm sizes. Ice crystals nucleate within the large sized droplets, grow up and fill up the droplets. Later, the ice crystals grow continuously through desublimation. At 600 Pa, the metastable liquid grows quickly, with some ice nuclei floating in it, and the liquid-solid coexistence state exists for a long time. By lowering the vapour pressure and/or increasing the substrate temperature, ice sublimates into vapour phase, and especially, the remaining ice forms a porous structure due to preferential sublimation in the concave regions, which can be explained with surface tension effect. Interestingly, although it should be forbidden for ice to transform into liquid phase when the temperature is well below 0 °C, liquid like droplets form during the ice sublimation process, which is attributed to the surface tension effect and the quasiliquid layers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/864992','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/864992"><span>Method for treating a nuclear process off-<span class="hlt">gas</span> stream</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Pence, Dallas T.; Chou, Chun-Chao</p> <p>1984-01-01</p> <p>Disclosed is a method for selectively removing and recovering the noble <span class="hlt">gas</span> and other gaseous components typically emitted during nuclear process operations. The method is adaptable and useful for treating dissolver off-<span class="hlt">gas</span> effluents released during reprocessing of spent nuclear fuels whereby to permit radioactive contaminant recovery prior to releasing the remaining off-gases to the atmosphere. Briefly, the method sequentially comprises treating the off-<span class="hlt">gas</span> stream to preliminarily remove NO.sub.x, hydrogen and carbon-containing organic compounds, and semivolatile fission product metal oxide components therefrom; adsorbing iodine components on silver-<span class="hlt">exchanged</span> mordenite; removing water vapor carried by said stream by means of a molecular sieve; selectively removing the carbon dioxide components of said off-<span class="hlt">gas</span> stream by means of a molecular sieve; selectively removing xenon in <span class="hlt">gas</span> phase by passing said stream through a molecular sieve comprising silver-<span class="hlt">exchanged</span> mordenite; selectively separating krypton from oxygen by means of a molecular sieve comprising silver-<span class="hlt">exchanged</span> mordenite; selectively separating krypton from the bulk nitrogen stream using a molecular sieve comprising silver-<span class="hlt">exchanged</span> mordenite cooled to about -140.degree. to -160.degree. C.; concentrating the desorbed krypton upon a molecular sieve comprising silver-<span class="hlt">exchange</span> mordenite cooled to about -140.degree. to -160.degree. C.; and further cryogenically concentrating, and the recovering for storage, the desorbed krypton.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25830350','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25830350"><span>Peach water relations, <span class="hlt">gas</span> <span class="hlt">exchange</span>, growth and shoot mortality under water deficit in semi-arid weather conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rahmati, Mitra; Davarynejad, Gholam Hossein; Génard, Michel; Bannayan, Mohammad; Azizi, Majid; Vercambre, Gilles</p> <p>2015-01-01</p> <p>In this study the sensitivity of peach tree (Prunus persica L.) to three water stress levels from mid-pit hardening until harvest was assessed. Seasonal patterns of shoot and fruit growth, <span class="hlt">gas</span> <span class="hlt">exchange</span> (leaf photosynthesis, stomatal conductance and transpiration) as well as carbon (C) storage/mobilization were evaluated in relation to plant water status. A simple C balance model was also developed to investigate sink-source relationship in relation to plant water status at the tree level. The C source was estimated through the leaf area dynamics and leaf photosynthesis rate along the season. The C sink was estimated for maintenance respiration and growth of shoots and fruits. Water stress significantly reduced <span class="hlt">gas</span> <span class="hlt">exchange</span>, and fruit, and shoot growth, but increased fruit dry matter concentration. Growth was more affected by water deficit than photosynthesis, and shoot growth was more sensitive to water deficit than fruit growth. Reduction of shoot growth was associated with a decrease of shoot elongation, emergence, and high shoot mortality. Water scarcity affected tree C assimilation due to two interacting factors: (i) reduction in leaf photosynthesis (-23% and -50% under moderate (MS) and severe (SS) water stress compared to low (LS) stress during growth season) and (ii) reduction in total leaf area (-57% and -79% under MS and SS compared to LS at harvest). Our field data analysis suggested a Ψstem threshold of -1.5 MPa below which daily net C gain became negative, i.e. C assimilation became lower than C needed for respiration and growth. Negative C balance under MS and SS associated with decline of trunk carbohydrate reserves--may have led to drought-induced vegetative mortality.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12010472','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12010472"><span>Water relations and <span class="hlt">gas</span> <span class="hlt">exchange</span> in poplar and willow under water stress and elevated atmospheric CO2.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Johnson, Jon D; Tognetti, Roberto; Paris, Piero</p> <p>2002-05-01</p> <p>Predictions of shifts in rainfall patterns as atmospheric [CO2] increases could impact the growth of fast growing trees such as Populus spp. and Salix spp. and the interaction between elevated CO2 and water stress in these species is unknown. The objectives of this study were to characterize the responses to elevated CO2 and water stress in these two species, and to determine if elevated CO2 mitigated drought stress effects. <span class="hlt">Gas</span> <span class="hlt">exchange</span>, water potential components, whole plant transpiration and growth response to soil drying and recovery were assessed in hybrid poplar (clone 53-246) and willow (Salix sagitta) rooted cuttings growing in either ambient (350 &mgr;mol mol-1) or elevated (700 &mgr;mol mol-1) atmospheric CO2 concentration ([CO2]). Predawn water potential decreased with increasing water stress while midday water potentials remained unchanged (isohydric response). Turgor potentials at both predawn and midday increased in elevated [CO2], indicative of osmotic adjustment. <span class="hlt">Gas</span> <span class="hlt">exchange</span> was reduced by water stress while elevated [CO2] increased photosynthetic rates, reduced leaf conductance and nearly doubled instantaneous transpiration efficiency in both species. Dark respiration decreased in elevated [CO2] and water stress reduced Rd in the trees growing in ambient [CO2]. Willow had 56% lower whole plant hydraulic conductivity than poplar, and showed a 14% increase in elevated [CO2] while poplar was unresponsive. The physiological responses exhibited by poplar and willow to elevated [CO2] and water stress, singly, suggest that these species respond like other tree species. The interaction of [CO2] and water stress suggests that elevated [CO2] did mitigate the effects of water stress in willow, but not in poplar.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4382189','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4382189"><span>Peach Water Relations, <span class="hlt">Gas</span> <span class="hlt">Exchange</span>, Growth and Shoot Mortality under Water Deficit in Semi-Arid Weather Conditions</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rahmati, Mitra; Davarynejad, Gholam Hossein; Génard, Michel; Bannayan, Mohammad; Azizi, Majid; Vercambre, Gilles</p> <p>2015-01-01</p> <p>In this study the sensitivity of peach tree (Prunus persica L.) to three water stress levels from mid-pit hardening until harvest was assessed. Seasonal patterns of shoot and fruit growth, <span class="hlt">gas</span> <span class="hlt">exchange</span> (leaf photosynthesis, stomatal conductance and transpiration) as well as carbon (C) storage/mobilization were evaluated in relation to plant water status. A simple C balance model was also developed to investigate sink-source relationship in relation to plant water status at the tree level. The C source was estimated through the leaf area dynamics and leaf photosynthesis rate along the season. The C sink was estimated for maintenance respiration and growth of shoots and fruits. Water stress significantly reduced <span class="hlt">gas</span> <span class="hlt">exchange</span>, and fruit, and shoot growth, but increased fruit dry matter concentration. Growth was more affected by water deficit than photosynthesis, and shoot growth was more sensitive to water deficit than fruit growth. Reduction of shoot growth was associated with a decrease of shoot elongation, emergence, and high shoot mortality. Water scarcity affected tree C assimilation due to two interacting factors: (i) reduction in leaf photosynthesis (-23% and -50% under moderate (MS) and severe (SS) water stress compared to low (LS) stress during growth season) and (ii) reduction in total leaf area (-57% and -79% under MS and SS compared to LS at harvest). Our field data analysis suggested a Ψstem threshold of -1.5 MPa below which daily net C gain became negative, i.e. C assimilation became lower than C needed for respiration and growth. Negative C balance under MS and SS associated with decline of trunk carbohydrate reserves – may have led to drought-induced vegetative mortality. PMID:25830350</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=computer+AND+medicine&pg=3&id=EJ788526','ERIC'); return false;" href="https://eric.ed.gov/?q=computer+AND+medicine&pg=3&id=EJ788526"><span>Teaching Pulmonary <span class="hlt">Gas</span> <span class="hlt">Exchange</span> Physiology Using Computer Modeling</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Kapitan, Kent S.</p> <p>2008-01-01</p> <p>Students often have difficulty understanding the relationship of O[subscript 2] consumption, CO[subscript 2] production, cardiac output, and distribution of ventilation-perfusion ratios in the lung to the final arterial blood <span class="hlt">gas</span> composition. To overcome this difficulty, I have developed an interactive computer simulation of pulmonary <span class="hlt">gas</span> exchange…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5735977','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5735977"><span>Assessing the Effects of Water Deficit on Photosynthesis Using Parameters Derived from Measurements of Leaf <span class="hlt">Gas</span> <span class="hlt">Exchange</span> and of Chlorophyll a Fluorescence</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Urban, Laurent; Aarrouf, Jawad; Bidel, Luc P. R.</p> <p>2017-01-01</p> <p>Water deficit (WD) is expected to increase in intensity, frequency and duration in many parts of the world as a consequence of global change, with potential negative effects on plant <span class="hlt">gas</span> <span class="hlt">exchange</span> and growth. We review here the parameters that can be derived from measurements made on leaves, in the field, and that can be used to assess the effects of WD on the components of plant photosynthetic rate, including stomatal conductance, mesophyll conductance, photosynthetic capacity, light absorbance, and efficiency of absorbed light conversion into photosynthetic electron transport. We also review some of the parameters related to dissipation of excess energy and to rerouting of electron fluxes. Our focus is mainly on the techniques of <span class="hlt">gas</span> <span class="hlt">exchange</span> measurements and of measurements of chlorophyll a fluorescence (ChlF), either alone or combined. But we put also emphasis on some of the parameters derived from analysis of the induction phase of maximal ChlF, notably because they could be used to assess damage to photosystem II. Eventually we briefly present the non-destructive methods based on the ChlF excitation ratio method which can be used to evaluate non-destructively leaf contents in anthocyanins and flavonols. PMID:29312367</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29312367','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29312367"><span>Assessing the Effects of Water Deficit on Photosynthesis Using Parameters Derived from Measurements of Leaf <span class="hlt">Gas</span> <span class="hlt">Exchange</span> and of Chlorophyll a Fluorescence.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Urban, Laurent; Aarrouf, Jawad; Bidel, Luc P R</p> <p>2017-01-01</p> <p>Water deficit (WD) is expected to increase in intensity, frequency and duration in many parts of the world as a consequence of global change, with potential negative effects on plant <span class="hlt">gas</span> <span class="hlt">exchange</span> and growth. We review here the parameters that can be derived from measurements made on leaves, in the field, and that can be used to assess the effects of WD on the components of plant photosynthetic rate, including stomatal conductance, mesophyll conductance, photosynthetic capacity, light absorbance, and efficiency of absorbed light conversion into photosynthetic electron transport. We also review some of the parameters related to dissipation of excess energy and to rerouting of electron fluxes. Our focus is mainly on the techniques of <span class="hlt">gas</span> <span class="hlt">exchange</span> measurements and of measurements of chlorophyll a fluorescence (ChlF), either alone or combined. But we put also emphasis on some of the parameters derived from analysis of the induction phase of maximal ChlF, notably because they could be used to assess damage to photosystem II. Eventually we briefly present the non-destructive methods based on the ChlF excitation ratio method which can be used to evaluate non-destructively leaf contents in anthocyanins and flavonols.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.B32C..01H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.B32C..01H"><span>Small ponds play big role in greenhouse <span class="hlt">gas</span> emissions from inland waters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holgerson, M.; Raymond, P. A.</p> <p>2017-12-01</p> <p>Inland waters are an important part of the global carbon cycle, but there is uncertainty in estimating their greenhouse <span class="hlt">gas</span> emissions. Uncertainty stems from different models and variable estimates of surface water <span class="hlt">gas</span> concentrations, <span class="hlt">gas</span> <span class="hlt">exchange</span> rates, and the global size distribution of water bodies. Emissions from small water bodies are especially difficult to estimate because they are not globally mapped and few studies have assessed their greenhouse <span class="hlt">gas</span> concentrations and <span class="hlt">gas</span> <span class="hlt">exchange</span> rates. To overcome these limitations, we studied greenhouse gases and <span class="hlt">gas</span> <span class="hlt">exchange</span> rates in small ponds in temperate forests of the northeastern United States. We then compiled our data with direct measurements of CO2 and CH4 concentrations from 427 ponds and lakes worldwide, and upscaled to estimate greenhouse <span class="hlt">gas</span> emissions using estimates of <span class="hlt">gas</span> <span class="hlt">exchange</span> rates and the size distribution of lakes. We found that small ponds play a disproportionately large role in greenhouse <span class="hlt">gas</span> emissions. While small ponds only account for about 9% of global lakes and ponds by area, they contribute 15% of CO2 and 41% of diffusive CH4 emissions from inland freshwaters. Secondly, we measured <span class="hlt">gas</span> <span class="hlt">exchange</span> velocities (k) in small ponds and compiled direct measurements of k from 67 global water bodies. We found that k is low but highly variable in small ponds, and increases and becomes even more variable with lake size, a finding that is not currently included in global carbon models. In a third study, we found that <span class="hlt">gas</span> <span class="hlt">exchange</span> in small ponds is highly sensitive to overnight cooling, which can lead to short bursts of increased k at night, with implications for greenhouse <span class="hlt">gas</span> emissions. Overall, these studies show that small ponds are a critical part of the global carbon cycle, and also highlight many knowledge gaps. Therefore, understanding small pond carbon cycling is an important research priority.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..278a2032Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..278a2032Y"><span>Numerical modeling and analytical modeling of cryogenic carbon capture in a de-sublimating heat <span class="hlt">exchanger</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yu, Zhitao; Miller, Franklin; Pfotenhauer, John M.</p> <p>2017-12-01</p> <p>Both a numerical and analytical model of the heat and mass transfer processes in a CO2, N2 mixture <span class="hlt">gas</span> de-sublimating cross-flow finned duct heat <span class="hlt">exchanger</span> system is developed to predict the heat transferred from a mixture <span class="hlt">gas</span> to liquid nitrogen and the de-sublimating rate of CO2 in the mixture <span class="hlt">gas</span>. The mixture <span class="hlt">gas</span> outlet temperature, liquid nitrogen outlet temperature, CO2 mole fraction, temperature distribution and de-sublimating rate of CO2 through the whole heat <span class="hlt">exchanger</span> was computed using both the numerical and analytic model. The numerical model is built using EES [1] (engineering equation solver). According to the simulation, a cross-flow finned duct heat <span class="hlt">exchanger</span> can be designed and fabricated to validate the models. The performance of the heat <span class="hlt">exchanger</span> is evaluated as functions of dimensionless variables, such as the ratio of the mass flow rate of liquid nitrogen to the mass flow rate of inlet flue <span class="hlt">gas</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25895891','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25895891"><span><span class="hlt">Gas</span>-Phase Hydrogen-Deuterium <span class="hlt">Exchange</span> Labeling of Select Peptide Ion Conformer Types: a Per-Residue Kinetics Analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Khakinejad, Mahdiar; Kondalaji, Samaneh Ghassabi; Tafreshian, Amirmahdi; Valentine, Stephen J</p> <p>2015-07-01</p> <p>The per-residue, <span class="hlt">gas</span>-phase hydrogen deuterium <span class="hlt">exchange</span> (HDX) kinetics for individual amino acid residues on selected ion conformer types of the model peptide KKDDDDDIIKIIK have been examined using ion mobility spectrometry (IMS) and HDX-tandem mass spectrometry (MS/MS) techniques. The [M + 4H](4+) ions exhibit two major conformer types with collision cross sections of 418 Å(2) and 446 Å(2); the [M + 3H](3+) ions also yield two different conformer types having collision cross sections of 340 Å(2) and 367 Å(2). Kinetics plots of HDX for individual amino acid residues reveal fast- and slow-<span class="hlt">exchanging</span> hydrogens. The contributions of each amino acid residue to the overall conformer type rate constant have been estimated. For this peptide, N- and C-terminal K residues exhibit the greatest contributions for all ion conformer types. Interior D and I residues show decreased contributions. Several charge state trends are observed. On average, the D residues of the [M + 3H](3+) ions show faster HDX rate contributions compared with [M + 4H](4+) ions. In contrast the interior I8 and I9 residues show increased accessibility to <span class="hlt">exchange</span> for the more elongated [M + 4H](4+) ion conformer type. The contribution of each residue to the overall uptake rate showed a good correlation with a residue hydrogen accessibility score model calculated using a distance from charge site and initial incorporation site for nominal structures obtained from molecular dynamic simulations (MDS).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16665243','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16665243"><span>Photosynthesis Decrease and Stomatal Control of <span class="hlt">Gas</span> <span class="hlt">Exchange</span> in Abies alba Mill. in Response to Vapor Pressure Difference.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Guehl, J M; Aussenac, G</p> <p>1987-02-01</p> <p>The responses of steady state CO(2) assimilation rate (A), transpiration rate (E), and stomatal conductance (g(s)) to changes in leaf-to-air vapor pressure difference (DeltaW) were examined on different dates in shoots from Abies alba trees growing outside. In Ecouves, a provenance representative of wet oceanic conditions in Northern France, both A and g(s) decreased when DeltaW was increased from 4.6 to 14.5 Pa KPa(-1). In Nebias, which represented the dry end of the natural range of A. alba in southern France, A and g(s) decreased only after reaching peak levels at 9.0 and 7.0 Pa KPa(-1), respectively. The representation of the data in assimilation rate (A) versus intercellular CO(2) partial pressure (C(i)) graphs allowed us to determine how stomata and mesophyll photosynthesis interacted when DeltaW was increased. Changes in A were primarily due to alterations in mesophyll photosynthesis. At high DeltaW, and especially in Ecouves when soil water deficit prevailed, A declined, while C(i) remained approximately constant, which may be interpreted as an adjustment of g(s) to changes in mesophyll photosynthesis. Such a stomatal control of <span class="hlt">gas</span> <span class="hlt">exchange</span> appeared as an alternative to the classical feedforward interpretation of E versus DeltaW responses with a peak rate of E. The <span class="hlt">gas</span> <span class="hlt">exchange</span> response to DeltaW was also characterized by considerable deviations from the optimization theory of IR Cowan and GD Farquhar (1977 Symp Soc Exp Biol 31: 471-505).</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/32763','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/32763"><span>Short-term impacts of nutrient manipulations on leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and biomass partitioning in contrasting 2-year-old Pinus taeda clones during seedling establishment</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Michael C. Tyree; John R. Seiler; Chris A. Maier</p> <p>2009-01-01</p> <p>We conducted a 1-year greenhouse experiment to assess the impact of nutrient manipulations on seedling growth, biomass partitioning, and leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> between two fast growing Pinus taeda clones that differed in growth efficiency. After 1 year we observed significant treatment and treatment by clone effects on growth, biomass partitioning, and...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26771117','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26771117"><span>Galectin-3 Is Associated with Restrictive Lung Disease and Interstitial Lung <span class="hlt">Abnormalities</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ho, Jennifer E; Gao, Wei; Levy, Daniel; Santhanakrishnan, Rajalakshmi; Araki, Tetsuro; Rosas, Ivan O; Hatabu, Hiroto; Latourelle, Jeanne C; Nishino, Mizuki; Dupuis, Josée; Washko, George R; O'Connor, George T; Hunninghake, Gary M</p> <p>2016-07-01</p> <p>Galectin-3 (Gal-3) has been implicated in the development of pulmonary fibrosis in experimental studies, and Gal-3 levels have been found to be elevated in small studies of human pulmonary fibrosis. We sought to study whether circulating Gal-3 concentrations are elevated early in the course of pulmonary fibrosis. We examined 2,596 Framingham Heart Study participants (mean age, 57 yr; 54% women; 14% current smokers) who underwent Gal-3 assessment using plasma samples and pulmonary function testing between 1995 and 1998. Of this sample, 1,148 underwent subsequent volumetric chest computed tomography. Higher Gal-3 concentrations were associated with lower lung volumes (1.4% decrease in percentage of predicted FEV1 per 1 SD increase in log Gal-3; 95% confidence interval [CI], 0.8-2.0%; P < 0.001; 1.2% decrease in percentage of predicted FVC; 95% CI, 0.6-1.8%; P < 0.001) and decreased diffusing capacity of the lung for carbon monoxide (2.1% decrease; 95% CI, 1.3-2.9%; P < 0.001). These associations remained significant after multivariable adjustment (P ≤ 0.008 for all). Compared with the lowest quartile, participants in the highest Gal-3 quartile were more than twice as likely to have interstitial lung <span class="hlt">abnormalities</span> visualized by computed tomography (multivariable-adjusted odds ratio, 2.67; 95% CI, 1.49-4.76; P < 0.001). Elevated Gal-3 concentrations are associated with interstitial lung <span class="hlt">abnormalities</span> coupled with a restrictive pattern, including decreased lung volumes and altered <span class="hlt">gas</span> <span class="hlt">exchange</span>. These findings suggest a potential role for Gal-3 in early stages of pulmonary fibrosis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20080046158&hterms=modeling+transfer+heat&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dmodeling%2Btransfer%2Bheat','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20080046158&hterms=modeling+transfer+heat&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dmodeling%2Btransfer%2Bheat"><span>Investigation of Condensing Ice Heat <span class="hlt">Exchangers</span> for MTSA Technology Development</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Padilla, Sebastian; Powers, Aaron; Ball, Tyler; Iacomini, Christie; Paul, Heather, L.</p> <p>2008-01-01</p> <p>Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed for thermal, carbon dioxide (CO2) and humidity control for a Portable Life Support Subsystem (PLSS). Metabolically-produced CO2 present in the ventilation <span class="hlt">gas</span> of a PLSS is collected using a CO2selective adsorbent via temperature swing adsorption. The temperature swing is initiated through cooling to well below metabolic temperatures. Cooling is achieved with a sublimation heat <span class="hlt">exchanger</span> using water or liquid carbon dioxide (LCO2) expanded below sublimation temperature when exposed to low pressure or vacuum. Subsequent super heated vapor, as well as additional coolant, is used to further cool the astronaut. The temperature swing on the adsorbent is then completed by warming the adsorbent with a separate condensing ice heat <span class="hlt">exchanger</span> (CIHX) using metabolic heat from moist ventilation <span class="hlt">gas</span>. The condensed humidity in the ventilation <span class="hlt">gas</span> is recycled at the habitat. The water condensation from the ventilation <span class="hlt">gas</span> is a significant heat transfer mechanism for the warming of the adsorbent bed because it represents as much as half of the energy potential in the moist ventilation <span class="hlt">gas</span>. Designing a heat <span class="hlt">exchanger</span> to efficiently transfer this energy to the adsorbent bed and allow the collection of the water is a challenge since the CIHX will operate in a temperature range from 210K to 280K. The ventilation <span class="hlt">gas</span> moisture will first freeze and then thaw, sometimes existing in three phases simultaneously. A NASA Small Business Innovative Research (SBIR) Phase 1 contract was performed to investigate condensing and icing as applied to MTSA to enable higher fidelity modeling and assess the impact of geometry variables on CIHX performance for future CIHX design optimization. Specifically, a design tool was created using analytical relations to explore the complex, interdependent design space of a condensing ice heat <span class="hlt">exchanger</span>. Numerous variables were identified as having nontrivial contributions</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ThEng..63...35I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ThEng..63...35I"><span>Investigation of heat <span class="hlt">exchangers</span> for energy conversion systems of megawatt-class space power plants</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ilmov, D. N.; Mamontov, Yu. N.; Skorohodov, A. S.; Smolyarov, V. A.; Filatov, N. I.</p> <p>2016-01-01</p> <p>The specifics of operation (high temperatures in excess of 1000 K and large pressure drops of several megapascals between "hot" and "cold" coolant paths) of heat <span class="hlt">exchangers</span> in the closed circuit of a gasturbine power converter operating in accordance with the Brayton cycle with internal heat recovery are analyzed in the context of construction of space propulsion systems. The design of a heat-<span class="hlt">exchange</span> matrix made from doubly convex stamped plates with a specific surface relief is proposed. This design offers the opportunity to construct heat <span class="hlt">exchangers</span> with the required parameters (strength, rigidity, weight, and dimensions) for the given operating conditions. The diagram of the working area of a test bench is presented, and the experimental techniques are outlined. The results of experimental studies of heat <span class="hlt">exchange</span> and flow regimes in the models of heat <span class="hlt">exchangers</span> with matrices containing 50 and 300 plates for two pairs of coolants (<span class="hlt">gas-gas</span> and <span class="hlt">gas</span>-liquid) are detailed. A criterion equation for the Nusselt number in the range of Reynolds numbers from 200 to 20 000 is proposed. The coefficients of hydraulic resistance for each coolant path are determined as functions of the Reynolds number. It is noted that the pressure in the water path in the "<span class="hlt">gas</span>-liquid" series of experiments remained almost constant. This suggests that no well-developed processes of vaporization occurred within this heat-<span class="hlt">exchange</span> matrix design even when the temperature drop between <span class="hlt">gas</span> and water was as large as tens or hundreds of degrees. The obtained results allow one to design flight heat <span class="hlt">exchangers</span> for various space power plants.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.H53E0523S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.H53E0523S"><span>A Test of the Optimality Approach to Modelling Canopy <span class="hlt">gas</span> <span class="hlt">Exchange</span> by Natural Vegetation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schymanski, S. J.; Sivapalan, M.; Roderick, M. L.; Beringer, J.; Hutley, L. B.</p> <p>2005-12-01</p> <p>Natural vegetation has co-evolved with its environment over a long period of time and natural selection has led to a species composition that is most suited for the given conditions. Part of this adaptation is the vegetation's water use strategy, which determines the amount and timing of water extraction from the soil. Knowing that water extraction by vegetation often accounts for over 90% of the annual water balance in some places, we need to understand its controls if we want to properly model the hydrologic cycle. Water extraction by roots is driven by transpiration from the canopy, which in turn is an inevitable consequence of CO2 uptake for photosynthesis. Photosynthesis provides plants with their main building material, carbohydrates, and with the energy necessary to thrive and prosper in their environment. Therefore we expect that natural vegetation would have evolved an optimal water use strategy to maximise its `net carbon profit' (the difference between carbon acquired by photosynthesis and carbon spent on maintenance of the organs involved in its uptake). Based on this hypothesis and on an ecophysiological <span class="hlt">gas</span> <span class="hlt">exchange</span> and photosynthesis model (Cowan and Farquhar 1977; von Caemmerer 2000), we model the optimal vegetation for a site in Howard Springs (N.T., Australia) and compare the modelled fluxes with measurements by Beringer, Hutley et al. (2003). The comparison gives insights into theoretical and real controls on transpiration and photosynthesis and tests the optimality approach to modelling <span class="hlt">gas</span> <span class="hlt">exchange</span> of natural vegetation with unknown properties. The main advantage of the optimality approach is that no assumptions about the particular vegetation on a site are needed, which makes it very powerful for predicting vegetation response to long-term climate- or land use change. Literature: Beringer, J., L. B. Hutley, et al. (2003). "Fire impacts on surface heat, moisture and carbon fluxes from a tropical savanna in northern Australia." International</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPS...306..289I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPS...306..289I"><span>Effect of through-plane polytetrafluoroethylene distribution in <span class="hlt">gas</span> diffusion layers on performance of proton <span class="hlt">exchange</span> membrane fuel cells</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ito, Hiroshi; Iwamura, Takuya; Someya, Satoshi; Munakata, Tetsuo; Nakano, Akihiro; Heo, Yun; Ishida, Masayoshi; Nakajima, Hironori; Kitahara, Tatsumi</p> <p>2016-02-01</p> <p>This experimental study identifies the effect of through-plane polytetrafluoroethylene (PTFE) distribution in <span class="hlt">gas</span> diffusion backing (GDB) on the performance of proton <span class="hlt">exchange</span> membrane fuel cells (PEMFC). PTFE-drying under vacuum pressure created a relatively uniform PTFE distribution in GDB compared to drying under atmospheric pressure. Carbon paper samples with different PTFE distributions due to the difference in drying conditions were prepared and used for the cathode <span class="hlt">gas</span> diffusion layer (GDL) of PEMFCs. Also investigated is the effect of MPL application on the performance for those samples. The current density (i) - voltage (V) characteristics of these PEMFCs measured under high relative humidity conditions clearly showed that, with or without MPL, the cell using the GDL with PTFE dried under vacuum condition showed better performance than that dried under atmospheric condition. It is suggested that this improved performance is caused by the efficient transport of liquid water through the GDB due to the uniform distribution of PTFE.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25495925','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25495925"><span>Grapevine species from varied native habitats exhibit differences in embolism formation/repair associated with leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and root pressure.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Knipfer, Thorsten; Eustis, Ashley; Brodersen, Craig; Walker, Andrew M; McElrone, Andrew J</p> <p>2015-08-01</p> <p>Drought induces xylem embolism formation, but grapevines can refill non-functional vessels to restore transport capacity. It is unknown whether vulnerability to embolism formation and ability to repair differ among grapevine species. We analysed in vivo embolism formation and repair using x-ray computed microtomography in three wild grapevine species from varied native habitats (Vitis riparia, V. arizonica, V. champinii) and related responses to measurements of leaf <span class="hlt">gas</span> <span class="hlt">exchange</span> and root pressure. Vulnerability to embolism formation was greatest in V. riparia, intermediate in V. arizonica and lowest in V. champinii. After re-watering, embolism repair was rapid and pronounced in V. riparia and V. arizonica, but limited or negligible in V. champinii even after numerous days. Similarly, root pressure measured after re-watering was positively correlated with drought stress severity for V. riparia and V. arizonica (species exhibiting embolism repair) but not for V. champinii. Drought-induced reductions in transpiration were greatest for V. riparia and least in V. champinii. Recovery of transpiration after re-watering was delayed for all species, but was greatest for V. champinii and most rapid in V. arizonica. These species exhibit varied responses to drought stress that involve maintenance/recovery of xylem transport capacity coordinated with root pressure and <span class="hlt">gas</span> <span class="hlt">exchange</span> responses. © 2014 John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26ES...35a2003A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26ES...35a2003A"><span>The potential role of sea spray droplets in facilitating air-sea <span class="hlt">gas</span> transfer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Andreas, E. L.; Vlahos, P.; Monahan, E. C.</p> <p>2016-05-01</p> <p>For over 30 years, air-sea interaction specialists have been evaluating and parameterizing the role of whitecap bubbles in air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span>. To our knowledge, no one, however, has studied the mirror image process of whether sea spray droplets can facilitate air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span>. We are therefore using theory, data analysis, and numerical modeling to quantify the role of spray on air-sea <span class="hlt">gas</span> transfer. In this, our first formal work on this subject, we seek the rate-limiting step in spray-mediated <span class="hlt">gas</span> transfer by evaluating the three time scales that govern the <span class="hlt">exchange</span>: τ air , which quantifies the rate of transfer between the atmospheric <span class="hlt">gas</span> reservoir and the surface of the droplet; τ int , which quantifies the <span class="hlt">exchange</span> rate across the air-droplet interface; and τ aq , which quantifies <span class="hlt">gas</span> mixing within the aqueous solution droplet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/871722','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/871722"><span>Growth of oxide <span class="hlt">exchange</span> bias layers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Chaiken, Alison; Michel, Richard P.</p> <p>1998-01-01</p> <p>An oxide (NiO, CoO, NiCoO) antiferromagnetic <span class="hlt">exchange</span> bias layer produced by ion beam sputtering of an oxide target in pure argon (Ar) sputtering <span class="hlt">gas</span>, with no oxygen <span class="hlt">gas</span> introduced into the system. Antiferromagnetic oxide layers are used, for example, in magnetoresistive readback heads to shift the hysteresis loops of ferromagnetic films away from the zero field axis. For example, NiO <span class="hlt">exchange</span> bia layers have been fabricated using ion beam sputtering of an NiO target using Ar ions, with the substrate temperature at 200.degree. C., the ion beam voltage at 1000V and the beam current at 20 mA, with a deposition rate of about 0.2 .ANG./sec. The resulting NiO film was amorphous.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/672582','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/672582"><span>Growth of oxide <span class="hlt">exchange</span> bias layers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Chaiken, A.; Michel, R.P.</p> <p>1998-07-21</p> <p>An oxide (NiO, CoO, NiCoO) antiferromagnetic <span class="hlt">exchange</span> bias layer produced by ion beam sputtering of an oxide target in pure argon (Ar) sputtering <span class="hlt">gas</span>, with no oxygen <span class="hlt">gas</span> introduced into the system. Antiferromagnetic oxide layers are used, for example, in magnetoresistive readback heads to shift the hysteresis loops of ferromagnetic films away from the zero field axis. For example, NiO <span class="hlt">exchange</span> bias layers have been fabricated using ion beam sputtering of an NiO target using Ar ions, with the substrate temperature at 200 C, the ion beam voltage at 1000V and the beam current at 20 mA, with a deposition rate of about 0.2 {angstrom}/sec. The resulting NiO film was amorphous. 4 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/867698','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/867698"><span>Spark gap switch system with condensable dielectric <span class="hlt">gas</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Thayer, III, William J.</p> <p>1991-01-01</p> <p>A spark gap switch system is disclosed which is capable of operating at a high pulse rate comprising an insulated switch housing having a purging <span class="hlt">gas</span> entrance port and a <span class="hlt">gas</span> exit port, a pair of spaced apart electrodes each having one end thereof within the housing and defining a spark gap therebetween, an easily condensable and preferably low molecular weight insulating <span class="hlt">gas</span> flowing through the switch housing from the housing, a heat <span class="hlt">exchanger</span>/condenser for condensing the insulating <span class="hlt">gas</span> after it exits from the housing, a pump for recirculating the condensed insulating <span class="hlt">gas</span> as a liquid back to the housing, and a heater <span class="hlt">exchanger</span>/evaporator to vaporize at least a portion of the condensed insulating <span class="hlt">gas</span> back into a vapor prior to flowing the insulating <span class="hlt">gas</span> back into the housing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790003232','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790003232"><span>Fuel delivery system including heat <span class="hlt">exchanger</span> means</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Coffinberry, G. A. (Inventor)</p> <p>1978-01-01</p> <p>A fuel delivery system is presented wherein first and second heat <span class="hlt">exchanger</span> means are each adapted to provide the transfer of heat between the fuel and a second fluid such as lubricating oil associated with the <span class="hlt">gas</span> turbine engine. Valve means are included which are operative in a first mode to provide for flow of the second fluid through both first and second heat <span class="hlt">exchange</span> means and further operative in a second mode for bypassing the second fluid around the second heat <span class="hlt">exchanger</span> means.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993ONERA..75.....A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993ONERA..75.....A"><span>High temperature heat <span class="hlt">exchangers</span> for <span class="hlt">gas</span> turbines and future hypersonic air breathing propulsion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Avran, Patrick; Bernard, Pierre</p> <p></p> <p>After surveying the results of ONERA's investigations to date of metallic and ceramic heat <span class="hlt">exchangers</span> applicable to automotive and aircraft powerplants, which are primarily of finned-tube counterflow configuration, attention is given to the influence of heat-<span class="hlt">exchanger</span> effectiveness on fuel consumption and <span class="hlt">exchanger</span> dimensions and weight. Emphasis is placed on the results of studies of cryogenic heat <span class="hlt">exchangers</span> used by airbreathing hypersonic propulsion systems. The numerical codes developed by ONERA for the modeling of heat <span class="hlt">exchanger</span> thermodynamics are evaluated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1235301-kinetics-hydrogen-isotope-exchange-phase-pd','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1235301-kinetics-hydrogen-isotope-exchange-phase-pd"><span>Kinetics of hydrogen isotope <span class="hlt">exchange</span> in β-phase Pd-H-D</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Luo, Weifang; Cowgill, Donald F.</p> <p>2015-07-22</p> <p>Hydrogen isotope <span class="hlt">gas</span> <span class="hlt">exchange</span> within palladium powders is examined using a batch-type reactor coupled to a residual <span class="hlt">gas</span> analyzer (RGA). Furthermore, the <span class="hlt">exchange</span> rates in both directions (H 2 + PdD and D 2 + PdH) are measured in the temperature range 178–323 K for the samples with different particle sizes. The results show this batch-type <span class="hlt">exchange</span> is closely approximated as a first-order kinetic process with a rate directly proportional to the surface area of the powder particles. An <span class="hlt">exchange</span> rate constant of 1.40 ± 0.24 μmol H 2/atm cm 2 s is found for H 2 + PdD atmore » 298 K, 1.4 times higher than that for D 2 + PdH, with an activation energy of 25.0 ± 3.2 kJ/mol H for both <span class="hlt">exchange</span> directions. Finally, a comparison of <span class="hlt">exchange</span> measurement techniques shows these coefficients, and the fundamental <span class="hlt">exchange</span> probabilities are in good agreement with those obtained by NMR and flow techniques.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1422301','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1422301"><span>Maximum Potential Hydrogen <span class="hlt">Gas</span> Retention in the sRF Resin Ion <span class="hlt">Exchange</span> Column for the LAWPS Process</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Gauglitz, Phillip A.; Wells, Beric E.; Bottenus, Courtney LH</p> <p></p> <p>The Low-Activity Waste Pretreatment System (LAWPS) is being developed to provide treated supernatant liquid from the Hanford tank farms directly to the Low-Activity Waste (LAW) Vitrification Facility at the Hanford Tank Waste Treatment and Immobilization Plant. The design and development of the LAWPS is being conducted by Washington River Protection Solutions, LLC. A key process in LAWPS is the removal of radioactive Cs in ion <span class="hlt">exchange</span> (IX) columns filled with spherical resorcinol-formaldehyde (sRF) resin. One accident scenario being evaluated is the loss of liquid flow through the sRF resin bed after it has been loaded with radioactive Cs and hydrogenmore » <span class="hlt">gas</span> is being generated by radiolysis. In normal operations, the generated hydrogen is expected to remain dissolved in the liquid and be continuously removed by liquid flow. For an accident scenario with a loss of flow, hydrogen <span class="hlt">gas</span> can be retained within the IX column both in the sRF resin and below the bottom screen that supports the resin within the column. The purpose of this report is to summarize calculations that estimate the upper-bound volume of hydrogen <span class="hlt">gas</span> that can be retained in the column and potentially be released to the headspace of the IX column or to process equipment connected to the IX column and, thus, pose a flammability hazard.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100026667','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100026667"><span>A Mass Computation Model for Lightweight Brayton Cycle Regenerator Heat <span class="hlt">Exchangers</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Juhasz, Albert J.</p> <p>2010-01-01</p> <p>Based on a theoretical analysis of convective heat transfer across large internal surface areas, this paper discusses the design implications for generating lightweight <span class="hlt">gas-gas</span> heat <span class="hlt">exchanger</span> designs by packaging such areas into compact three-dimensional shapes. Allowances are made for hot and cold inlet and outlet headers for assembly of completed regenerator (or recuperator) heat <span class="hlt">exchanger</span> units into closed cycle <span class="hlt">gas</span> turbine flow ducting. Surface area and resulting volume and mass requirements are computed for a range of heat <span class="hlt">exchanger</span> effectiveness values and internal heat transfer coefficients. Benefit cost curves show the effect of increasing heat <span class="hlt">exchanger</span> effectiveness on Brayton cycle thermodynamic efficiency on the plus side, while also illustrating the cost in heat <span class="hlt">exchanger</span> required surface area, volume, and mass requirements as effectiveness is increased. The equations derived for counterflow and crossflow configurations show that as effectiveness values approach unity, or 100 percent, the required surface area, and hence heat <span class="hlt">exchanger</span> volume and mass tend toward infinity, since the implication is that heat is transferred at a zero temperature difference. To verify the dimensional accuracy of the regenerator mass computational procedure, calculation of a regenerator specific mass, that is, heat <span class="hlt">exchanger</span> weight per unit working fluid mass flow, is performed in both English and SI units. Identical numerical values for the specific mass parameter, whether expressed in lb/(lb/sec) or kg/(kg/sec), show the dimensional consistency of overall results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100037206','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100037206"><span>A Mass Computation Model for Lightweight Brayton Cycle Regenerator Heat <span class="hlt">Exchangers</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Juhasz, Albert J.</p> <p>2010-01-01</p> <p>Based on a theoretical analysis of convective heat transfer across large internal surface areas, this paper discusses the design implications for generating lightweight <span class="hlt">gas-gas</span> heat <span class="hlt">exchanger</span> designs by packaging such areas into compact three-dimensional shapes. Allowances are made for hot and cold inlet and outlet headers for assembly of completed regenerator (or recuperator) heat <span class="hlt">exchanger</span> units into closed cycle <span class="hlt">gas</span> turbine flow ducting. Surface area and resulting volume and mass requirements are computed for a range of heat <span class="hlt">exchanger</span> effectiveness values and internal heat transfer coefficients. Benefit cost curves show the effect of increasing heat <span class="hlt">exchanger</span> effectiveness on Brayton cycle thermodynamic efficiency on the plus side, while also illustrating the cost in heat <span class="hlt">exchanger</span> required surface area, volume, and mass requirements as effectiveness is increased. The equations derived for counterflow and crossflow configurations show that as effectiveness values approach unity, or 100 percent, the required surface area, and hence heat <span class="hlt">exchanger</span> volume and mass tend toward infinity, since the implication is that heat is transferred at a zero temperature difference. To verify the dimensional accuracy of the regenerator mass computational procedure, calculation of a regenerator specific mass, that is, heat <span class="hlt">exchanger</span> weight per unit working fluid mass flow, is performed in both English and SI units. Identical numerical values for the specific mass parameter, whether expressed in lb/(lb/sec) or kg/ (kg/sec), show the dimensional consistency of overall results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/6262388','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/6262388"><span>Spent fuel behavior under <span class="hlt">abnormal</span> thermal transients during dry storage</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Stahl, D.; Landow, M.P.; Burian, R.J.</p> <p>1986-01-01</p> <p>This study was performed to determine the effects of <span class="hlt">abnormally</span> high temperatures on spent fuel behavior. Prior to testing, calculations using the CIRFI3 code were used to determine the steady-state fuel and cask component temperatures. The TRUMP code was used to determine transient heating rates under postulated <span class="hlt">abnormal</span> events during which convection cooling of the cask surfaces was obstructed by a debris bed covering the cask. The peak rate of temperature rise during the first 6 h was calculated to be about 15/sup 0/C/h, followed by a rate of about 1/sup 0/C/h. A Turkey Point spent fuel rod segment wasmore » heated to approx. 800/sup 0/C. The segment deformed uniformly with an average strain of 17% at failure and a local strain of 60%. Pretest characterization of the spent fuel consisted of visual examination, profilometry, eddy-current examination, gamma scanning, fission <span class="hlt">gas</span> collection, void volume measurement, fission <span class="hlt">gas</span> analysis, hydrogen analysis of the cladding, burnup analysis, cladding metallography, and fuel ceramography. Post-test characterization showed that the failure was a pinhole cladding breach. The results of the tests showed that spent fuel temperatures in excess of 700/sup 0/C are required to produce a cladding breach in fuel rods pressurized to 500 psing (3.45 MPa) under postulated <span class="hlt">abnormal</span> thermal transient cask conditions. The pinhole cladding breach that developed would be too small to compromise the confinement of spent fuel particles during an <span class="hlt">abnormal</span> event or after normal cooling conditions are restored. This behavior is similar to that found in other slow ramp tests with irradiated and nonirradiated rod sections and nonirradiated whole rods under conditions that bracketed postulated <span class="hlt">abnormal</span> heating rates. This similarity is attributed to annealing of the irradiation-strengthened Zircaloy cladding during heating. In both cases, the failure was a benign, ductile pinhole rupture.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28315238','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28315238"><span>Comprehensive <span class="hlt">Gas</span>-Phase Peptide Ion Structure Studies Using Ion Mobility Techniques: Part 2. <span class="hlt">Gas</span>-Phase Hydrogen/Deuterium <span class="hlt">Exchange</span> for Ion Population Estimation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Khakinejad, Mahdiar; Ghassabi Kondalaji, Samaneh; Tafreshian, Amirmahdi; Valentine, Stephen J</p> <p>2017-05-01</p> <p><span class="hlt">Gas</span>-phase hydrogen/deuterium <span class="hlt">exchange</span> (HDX) using D 2 O reagent and collision cross-section (CCS) measurements are utilized to monitor the ion conformers of the model peptide acetyl-PAAAAKAAAAKAAAAKAAAAK. The measurements are carried out on a home-built ion mobility instrument coupled to a linear ion trap mass spectrometer containing electron transfer dissociation (ETD) capabilities. ETD is utilized to obtain per-residue deuterium uptake data for select ion conformers, and a new algorithm is presented for interpreting the HDX data. Using molecular dynamics (MD) production data and a hydrogen accessibility scoring (HAS)-number of effective collisions (NEC) model, hypothetical HDX behavior is attributed to various in-silico candidate (CCS match) structures. The HAS-NEC model is applied to all candidate structures, and non-negative linear regression is employed to determine structure contributions resulting in the best match to deuterium uptake. The accuracy of the HAS-NEC model is tested with the comparison of predicted and experimental isotopic envelopes for several of the observed c-ions. It is proposed that <span class="hlt">gas</span>-phase HDX can be utilized effectively as a second criterion (after CCS matching) for filtering suitable MD candidate structures. In this study, the second step of structure elucidation, 13 nominal structures were selected (from a pool of 300 candidate structures) and each with a population contribution proposed for these ions. Graphical Abstract ᅟ.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27117807','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27117807"><span>Widespread activation of immunity and pro-inflammatory programs in peripheral blood leukocytes of HIV-infected patients with impaired lung <span class="hlt">gas</span> <span class="hlt">exchange</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Crothers, Kristina; Petrache, Irina; Wongtrakool, Cherry; Lee, Patty J; Schnapp, Lynn M; Gharib, Sina A</p> <p>2016-04-01</p> <p>HIV infection is associated with impaired lung <span class="hlt">gas</span> transfer as indicated by a low diffusing capacity (DLCO), but the mechanisms are not well understood. We hypothesized that HIV-associated <span class="hlt">gas</span> <span class="hlt">exchange</span> impairment is indicative of system-wide perturbations that could be reflected by alterations in peripheral blood leukocyte (PBL) gene expression. Forty HIV-infected (HIV(+)) and uninfected (HIV(-)) men with preserved versus low DLCO were enrolled. All subjects were current smokers and those with acute illness, lung diseases other than COPD or asthma were excluded. Total RNA was extracted from PBLs and hybridized to whole-genome microarrays. Gene set enrichment analysis (GSEA) was performed between HIV(+) versus HIV(-) subjects with preserved DLCO and those with low DLCO to identify differentially activated pathways. Using pathway-based analyses, we found that in subjects with preserved DLCO, HIV infection is associated with activation of processes involved in immunity, cell cycle, and apoptosis. Applying a similar analysis to subjects with low DLCO, we identified a much broader repertoire of pro-inflammatory and immune-related pathways in HIV(+) patients relative to HIV(-) subjects, with up-regulation of multiple interleukin pathways, interferon signaling, and toll-like receptor signaling. We confirmed elevated circulating levels of IL-6 in HIV(+) patients with low DLCO relative to the other groups. Our findings reveal that PBLs of subjects with HIV infection and low DLCO are distinguished by widespread enrichment of immuno-inflammatory programs. Activation of these pathways may alter the biology of circulating leukocytes and play a role in the pathogenesis of HIV-associated <span class="hlt">gas</span> <span class="hlt">exchange</span> impairment. © 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23874031','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23874031"><span>The lung in liver disease: old problem, new concepts.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fallon, Michael B; Zhang, Junlan</p> <p>2013-01-01</p> <p>Liver dysfunction has been recognized to influence the lung in many different clinical situations, although the mechanisms for these effects are not well understood. One increasingly recognized interaction, the hepatopulmonary syndrome (HPS) occurs in the context of cirrhosis and results when alveolar microvascular dilation causes arterial <span class="hlt">gas</span> <span class="hlt">exchange</span> <span class="hlt">abnormalities</span> and hypoxemia. HPS occurs in up to 30% of patients with cirrhosis and significantly increases mortality in affected patients. Currently, liver transplantation is the only curative therapy. Experimental biliary cirrhosis induced by common bile duct ligation (CBDL) in the rat reproduces the pulmonary vascular and <span class="hlt">gas</span> <span class="hlt">exchange</span> <span class="hlt">abnormalities</span> of human HPS and has been contrasted with other experimental models of cirrhosis in which HPS does not develop. Microvascular dilation, intravascular monocyte infiltration, and angiogenesis in the lung have been identified as pathologic features that drive <span class="hlt">gas</span> <span class="hlt">exchange</span> <span class="hlt">abnormalities</span> in experimental HPS. Our recent studies have identified biliary epithelium and activation and interaction between the endothelin-1 (ET-1)/endothelial endothelin B (ETB) receptor and CX3CL1/CX3CR1 pathways as important mechanisms for the observed pathologic events. These studies define novel interactions between the lung and liver in cirrhosis and may lead to effective medical therapies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19620001733','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19620001733"><span>Photosynthetic <span class="hlt">Gas</span> <span class="hlt">Exchange</span> in the Closed Ecosystem for Space. Phase II, Part III. Screening for Thermophilic Algae and Mutation Studies</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Richards, N. L.; Benoit, R. J.</p> <p>1961-01-01</p> <p>An algal screening and mutation study was undertaken to obtain algae superior to Chlorella 71105 for use in a photosynthetic <span class="hlt">gas</span> <span class="hlt">exchanger</span>. Of the forty-four thermophilic algae studied, eighteen appeared to have growth rates as great as Chlorella 71105. Optimization of the physical and chemical environments of these strains is recommended as a way to further improve growth rates and concomitant oxygen production. The mutation study revealed that Chlorella 71105 is relatively resistant to germicidal ultraviolet radiation. No high temperature mutants of Chlorella 71105 were found.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1058295','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1058295"><span><span class="hlt">Gas</span> <span class="hlt">Exchange</span> of Algae</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ammann, Elizabeth C. B.; Lynch, Victoria H.</p> <p>1965-01-01</p> <p>Continuously growing cultures of Chlorella pyrenoidosa Starr 252, operating at constant density and under constant environmental conditions, produced uniform photosynthetic quotient (PQ = CO2/O2) and O2 values during 6 months of observations. The PQ for the entire study was 0.90 ± 0.024. The PQ remained constant over a threefold light-intensity change and a threefold change in O2 production (0.90 ± 0.019). At low light intensities, when the rate of respiration approached the rate of photosynthesis, the PQ became extremely variable. Six lamps of widely different spectral-energy distribution produced no significant change in the PQ (0.90 ± 0.025). Oxygen production was directly related to the number of quanta available, irrespective of spectral-energy distribution. Such dependability in producing uniform PQ and O2 values warrants a consideration of algae to maintain a constant <span class="hlt">gas</span> environment for submarine or spaceship use. Images Fig. 1 PMID:14339260</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/874696','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/874696"><span>Hydraulically actuated <span class="hlt">gas</span> <span class="hlt">exchange</span> valve assembly and engine using same</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Carroll, Thomas S.; Taylor, Gregory O.</p> <p>2002-09-03</p> <p>An engine comprises a housing that defines a hollow piston cavity that is separated from a <span class="hlt">gas</span> passage by a valve seat. The housing further defines a biasing hydraulic cavity and a control hydraulic cavity. A <span class="hlt">gas</span> valve member is also included in the engine and is movable relative to the valve seat between an open position at which the hollow piston cavity is open to the <span class="hlt">gas</span> passage and a closed position in which the hollow piston cavity is blocked from the <span class="hlt">gas</span> passage. The <span class="hlt">gas</span> valve member includes a ring mounted on a valve piece and a retainer positioned between the ring and the valve piece. A closing hydraulic surface is included on the <span class="hlt">gas</span> valve member and is exposed to liquid pressure in the biasing hydraulic cavity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2049065','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2049065"><span>Bubble Continuous Positive Airway Pressure Enhances Lung Volume and <span class="hlt">Gas</span> <span class="hlt">Exchange</span> in Preterm Lambs</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Pillow, J. Jane; Hillman, Noah; Moss, Timothy J. M.; Polglase, Graeme; Bold, Geoff; Beaumont, Chris; Ikegami, Machiko; Jobe, Alan H.</p> <p>2007-01-01</p> <p>Rationale: The technique used to provide continuous positive airway pressure (CPAP) to the newborn may influence lung function and breathing efficiency. Objectives: To compare differences in <span class="hlt">gas</span> <span class="hlt">exchange</span> physiology and lung injury resulting from treatment of respiratory distress with either bubble or constant pressure CPAP and to determine if the applied flow influences short-term outcomes. Methods: Lambs (133 d gestation; term is 150 d) born via cesarean section were weighed, intubated, and treated with CPAP for 3 hours. Two groups were treated with 8 L/minute applied flow using the bubble (n = 12) or the constant pressure (n = 12) technique. A third group (n = 10) received the bubble method with 12 L/minute bias flow. Measurements at study completion included arterial blood gases, oxygraphy, capnography, tidal flow, multiple breath washout, lung mechanics, static pressure–volume curves, and bronchoalveolar lavage fluid protein. Measurements and Main Results: Birth weight and arterial <span class="hlt">gas</span> variables at 15 minutes were comparable. Flow (8 or 12 L/min) did not influence the 3-hour outcomes in the bubble group. Bubble technique was associated with a higher pH, PaO2, oxygen uptake, and area under the flow–volume curve, and a decreased alveolar protein, respiratory quotient, PaCO2, and ventilation inhomogeneity compared with the constant pressure group. Conclusions: Compared with constant pressure technique, bubble CPAP promotes enhanced airway patency during treatment of acute postnatal respiratory disease in preterm lambs and may offer protection against lung injury. PMID:17431223</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26475493','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26475493"><span><span class="hlt">Gas</span> transfer model to design a ventilator for neonatal total liquid ventilation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bonfanti, Mirko; Cammi, Antonio; Bagnoli, Paola</p> <p>2015-12-01</p> <p>The study was aimed to optimize the <span class="hlt">gas</span> transfer in an innovative ventilator for neonatal Total Liquid Ventilation (TLV) that integrates the pumping and oxygenation functions in a non-volumetric pulsatile device made of parallel flat silicone membranes. A computational approach was adopted to evaluate oxygen (O2) and carbon dioxide (CO2) <span class="hlt">exchanges</span> between the liquid perfluorocarbon (PFC) and the oxygenating <span class="hlt">gas</span>, as a function of the geometrical parameter of the device. A 2D semi-empirical model was implemented to this purpose using Comsol Multiphysics to study both the fluid dynamics and the <span class="hlt">gas</span> <span class="hlt">exchange</span> in the ventilator. Experimental <span class="hlt">gas</span> <span class="hlt">exchanges</span> measured with a preliminary prototype were compared to the simulation outcomes to prove the model reliability. Different device configurations were modeled to identify the optimal design able to guarantee the desired <span class="hlt">gas</span> transfer. Good agreement between experimental and simulation outcomes was obtained, validating the model. The optimal configuration, able to achieve the desired <span class="hlt">gas</span> <span class="hlt">exchange</span> (ΔpCO2 = 16.5 mmHg and ΔpO2 = 69 mmHg), is a device comprising 40 modules, 300 mm in length (total <span class="hlt">exchange</span> area = 2.28 m(2)). With this configuration <span class="hlt">gas</span> transfer performance is satisfactory for all the simulated settings, proving good adaptability of the device. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15968511','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15968511"><span>Microgravity does not alter plant stand <span class="hlt">gas</span> <span class="hlt">exchange</span> of wheat at moderate light levels and saturating CO2 concentration.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Monje, O; Stutte, G; Chapman, D</p> <p>2005-10-01</p> <p>Plant stand <span class="hlt">gas</span> <span class="hlt">exchange</span> was measured nondestructively in microgravity during the Photosynthesis Experiment Subsystem Testing and Operations experiment conducted onboard the International Space Station. Rates of evapotranspiration and photosynthesis measured in space were compared with ground controls to determine if microgravity directly affects whole-stand <span class="hlt">gas</span> <span class="hlt">exchange</span> of Triticum aestivum. During six 21-day experiment cycles, evapotranspiration was determined continuously from water addition rates to the nutrient delivery system, and photosynthesis was determined from the amount of CO2 added to maintain the chamber CO2 concentration setpoint. Plant stand evapotranspiration, net photosynthesis, and water use efficiency were not altered by microgravity. Although leaf area was significantly reduced in microgravity-grown plants compared to ground control plants, leaf area distribution was not affected enough to cause significant differences in the amounts of light absorbed by the flight and ground control plant stands. Microgravity also did not affect the response of evapotranspiration to changes in chamber vapor pressure difference of 12-day-old wheat plant stands. These results suggest that gravity naïve plants grown at moderate light levels (300 micromol m(-2) s(-1)) behave the same as ground control plants. This implies that future plant-based regenerative life support systems can be sized using 1 g data because water purification and food production rates operate at nearly the same rates as in 1 g at moderate light levels. However, it remains to be verified whether the present results are reproducible in plants grown under stronger light levels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AtmEn.178...31J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AtmEn.178...31J"><span>Seasonal atmospheric deposition and air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> of polycyclic aromatic hydrocarbons over the Yangtze River Estuary, East China Sea: Implications for source-sink processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jiang, Yuqing; Lin, Tian; Wu, Zilan; Li, Yuanyuan; Li, Zhongxia; Guo, Zhigang; Yao, Xiaohong</p> <p>2018-04-01</p> <p>In this work, air samples and surface seawater samples covering four seasons from March 2014 to January 2015 were collected from a background receptor site in the YRE to explore the seasonal fluxes of air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> and dry and wet deposition of 15 polycyclic aromatic hydrocarbons (PAHs) and their source-sink processes at the air-sea interface. The average dry and wet deposition fluxes of 15 PAHs were estimated as 879 ± 1393 ng m-2 d-1 and 755 ± 545 ng m-2 d-1, respectively. Gaseous PAH release from seawater to the atmosphere averaged 3114 ± 1999 ng m-2 d-1 in a year round. The air-sea <span class="hlt">gas</span> <span class="hlt">exchange</span> of PAHs was the dominant process at the air-sea interface in the YRE as the magnitude of volatilization flux of PAHs exceeded that of total dry and wet deposition. The <span class="hlt">gas</span> PAH <span class="hlt">exchange</span> flux was dominated by three-ring PAHs, with the highest value in summer and lowest in winter, indicating a marked seasonal variation owing to differences in Henry's law constants associated with temperature, as well as wind speed and gaseous-dissolved gradient among seasons. Based on the simplified mass balance estimation, a net 11 tons y-1 of PAHs (mainly three-ring PAHs) were volatilized from seawater to the atmosphere in a ∼20,000 km2 area in the YRE. Other than the year-round Yangtze River input and ocean ship emissions, the selective release of low-molecular-weight PAHs from bottom sediments in winter due to resuspension triggered by the East Asian winter monsoon is another potential source of PAHs. This work suggests that the source-sink processes of PAHs at the air-sea interface in the YRE play a crucial role in regional cycling of PAHs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/874239','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/874239"><span>Exhaust <span class="hlt">gas</span> purification system for lean burn engine</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Haines, Leland Milburn</p> <p>2002-02-19</p> <p>An exhaust <span class="hlt">gas</span> purification system for a lean burn engine includes a thermal mass unit and a NO.sub.x conversion catalyst unit downstream of the thermal mass unit. The NO.sub.x conversion catalyst unit includes at least one catalyst section. Each catalyst section includes a catalytic layer for converting NO.sub.x coupled to a heat <span class="hlt">exchanger</span>. The heat <span class="hlt">exchanger</span> portion of the catalyst section acts to maintain the catalytic layer substantially at a desired temperature and cools the exhaust <span class="hlt">gas</span> flowing from the catalytic layer into the next catalytic section in the series. In a further aspect of the invention, the exhaust <span class="hlt">gas</span> purification system includes a dual length exhaust pipe upstream of the NO.sub.x conversion catalyst unit. The dual length exhaust pipe includes a second heat <span class="hlt">exchanger</span> which functions to maintain the temperature of the exhaust <span class="hlt">gas</span> flowing into the thermal mass downstream near a desired average temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20090012387&hterms=heat+exchanger&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dheat%2Bexchanger','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20090012387&hterms=heat+exchanger&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dheat%2Bexchanger"><span>Investigation of Condensing Ice Heat <span class="hlt">Exchangers</span> for MTSA Technology Development</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Padilla, Sebastian; Powers, Aaron; Ball, Tyler; Lacomini, Christie; Paul, Heather L.</p> <p>2009-01-01</p> <p>Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed for thermal, carbon dioxide (CO2) and humidity control for a Portable Life Support Subsystem (PLSS). Metabolically-produced CO2 present in the ventilation <span class="hlt">gas</span> of a PLSS is collected using a CO2-selective adsorbent via temperature swing adsorption. The temperature swing is initiated through cooling to well below metabolic temperatures. Cooling is achieved with a sublimation heat <span class="hlt">exchanger</span> using water or liquid carbon dioxide (L CO2) expanded below sublimation temperature when exposed to low pressure or vacuum. Subsequent super heated vapor, as well as additional coolant, is used to further cool the astronaut. The temperature swing on the adsorbent is then completed by warming the adsorbent with a separate condensing ice heat <span class="hlt">exchanger</span> (CIHX) using metabolic heat from moist ventilation <span class="hlt">gas</span>. The condensed humidity in the ventilation <span class="hlt">gas</span> is recycled at the habitat. The water condensation from the ventilation <span class="hlt">gas</span> represents a significant source of potential energy for the warming of the adsorbent bed as it represents as much as half of the energy potential in the moist ventilation <span class="hlt">gas</span>. Designing a heat <span class="hlt">exchanger</span> to efficiently transfer this energy to the adsorbent bed and allow the collection of the water is a challenge since the CIHX will operate in a temperature range from 210K to 280K. The ventilation <span class="hlt">gas</span> moisture will first freeze and then thaw, sometimes existing in three phases simultaneously.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1421860-exchange-correlation-approximations-reduced-density-matrix-functional-theory-finite-temperature-capturing-magnetic-phase-transitions-homogeneous-electron-gas','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1421860-exchange-correlation-approximations-reduced-density-matrix-functional-theory-finite-temperature-capturing-magnetic-phase-transitions-homogeneous-electron-gas"><span><span class="hlt">Exchange</span>-correlation approximations for reduced-density-matrix-functional theory at finite temperature: Capturing magnetic phase transitions in the homogeneous electron <span class="hlt">gas</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Baldsiefen, Tim; Cangi, Attila; Eich, F. G.</p> <p></p> <p>Here, we derive an intrinsically temperature-dependent approximation to the correlation grand potential for many-electron systems in thermodynamical equilibrium in the context of finite-temperature reduced-density-matrix-functional theory (FT-RDMFT). We demonstrate its accuracy by calculating the magnetic phase diagram of the homogeneous electron <span class="hlt">gas</span>. We compare it to known limits from highly accurate quantum Monte Carlo calculations as well as to phase diagrams obtained within existing <span class="hlt">exchange</span>-correlation approximations from density functional theory and zero-temperature RDMFT.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1421860-exchange-correlation-approximations-reduced-density-matrix-functional-theory-finite-temperature-capturing-magnetic-phase-transitions-homogeneous-electron-gas','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1421860-exchange-correlation-approximations-reduced-density-matrix-functional-theory-finite-temperature-capturing-magnetic-phase-transitions-homogeneous-electron-gas"><span><span class="hlt">Exchange</span>-correlation approximations for reduced-density-matrix-functional theory at finite temperature: Capturing magnetic phase transitions in the homogeneous electron <span class="hlt">gas</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Baldsiefen, Tim; Cangi, Attila; Eich, F. G.; ...</p> <p>2017-12-18</p> <p>Here, we derive an intrinsically temperature-dependent approximation to the correlation grand potential for many-electron systems in thermodynamical equilibrium in the context of finite-temperature reduced-density-matrix-functional theory (FT-RDMFT). We demonstrate its accuracy by calculating the magnetic phase diagram of the homogeneous electron <span class="hlt">gas</span>. We compare it to known limits from highly accurate quantum Monte Carlo calculations as well as to phase diagrams obtained within existing <span class="hlt">exchange</span>-correlation approximations from density functional theory and zero-temperature RDMFT.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4960628','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4960628"><span>Galectin-3 Is Associated with Restrictive Lung Disease and Interstitial Lung <span class="hlt">Abnormalities</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gao, Wei; Levy, Daniel; Santhanakrishnan, Rajalakshmi; Araki, Tetsuro; Rosas, Ivan O.; Hatabu, Hiroto; Latourelle, Jeanne C.; Nishino, Mizuki; Dupuis, Josée; Washko, George R.; O’Connor, George T.; Hunninghake, Gary M.</p> <p>2016-01-01</p> <p>Rationale: Galectin-3 (Gal-3) has been implicated in the development of pulmonary fibrosis in experimental studies, and Gal-3 levels have been found to be elevated in small studies of human pulmonary fibrosis. Objectives: We sought to study whether circulating Gal-3 concentrations are elevated early in the course of pulmonary fibrosis. Methods: We examined 2,596 Framingham Heart Study participants (mean age, 57 yr; 54% women; 14% current smokers) who underwent Gal-3 assessment using plasma samples and pulmonary function testing between 1995 and 1998. Of this sample, 1,148 underwent subsequent volumetric chest computed tomography. Measurements and Main Results: Higher Gal-3 concentrations were associated with lower lung volumes (1.4% decrease in percentage of predicted FEV1 per 1 SD increase in log Gal-3; 95% confidence interval [CI], 0.8–2.0%; P < 0.001; 1.2% decrease in percentage of predicted FVC; 95% CI, 0.6–1.8%; P < 0.001) and decreased diffusing capacity of the lung for carbon monoxide (2.1% decrease; 95% CI, 1.3–2.9%; P < 0.001). These associations remained significant after multivariable adjustment (P ≤ 0.008 for all). Compared with the lowest quartile, participants in the highest Gal-3 quartile were more than twice as likely to have interstitial lung <span class="hlt">abnormalities</span> visualized by computed tomography (multivariable-adjusted odds ratio, 2.67; 95% CI, 1.49–4.76; P < 0.001). Conclusions: Elevated Gal-3 concentrations are associated with interstitial lung <span class="hlt">abnormalities</span> coupled with a restrictive pattern, including decreased lung volumes and altered <span class="hlt">gas</span> <span class="hlt">exchange</span>. These findings suggest a potential role for Gal-3 in early stages of pulmonary fibrosis. PMID:26771117</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ACP....17.8177K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ACP....17.8177K"><span>The boundary condition for vertical velocity and its interdependence with surface <span class="hlt">gas</span> <span class="hlt">exchange</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kowalski, Andrew S.</p> <p>2017-07-01</p> <p>The law of conservation of linear momentum is applied to surface <span class="hlt">gas</span> <span class="hlt">exchanges</span>, employing scale analysis to diagnose the vertical velocity (w) in the boundary layer. Net upward momentum in the surface layer is forced by evaporation (E) and defines non-zero vertical motion, with a magnitude defined by the ratio of E to the air density, as w = <mstyle displaystyle="false">E/ρ</mstyle>. This is true even right down at the surface where the boundary condition is w|0 = <mstyle displaystyle="false"><mfrac style="text">E/ρ|0</mfrac></mstyle> (where w|0 and ρ|0 represent the vertical velocity and density of air at the surface). This Stefan flow velocity implies upward transport of a non-diffusive nature that is a general feature of the troposphere but is of particular importance at the surface, where it assists molecular diffusion with upward <span class="hlt">gas</span> migration (of H2O, for example) but opposes that of downward-diffusing species like CO2 during daytime. The definition of flux-gradient relationships (eddy diffusivities) requires rectification to exclude non-diffusive transport, which does not depend on scalar gradients. At the microscopic scale, the role of non-diffusive transport in the process of evaporation from inside a narrow tube - with vapour transport into an overlying, horizontal airstream - was described long ago in classical mechanics and is routinely accounted for by chemical engineers, but has been neglected by scientists studying stomatal conductance. Correctly accounting for non-diffusive transport through stomata, which can appreciably reduce net CO2 transport and marginally boost that of water vapour, should improve characterisations of ecosystem and plant functioning.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760022616','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760022616"><span>Hydrogen rich <span class="hlt">gas</span> generator</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Houseman, J. (Inventor)</p> <p>1976-01-01</p> <p>A process and apparatus is described for producing a hydrogen rich <span class="hlt">gas</span> by introducing a liquid hydrocarbon fuel in the form of a spray into a partial oxidation region and mixing with a mixture of steam and air that is preheated by indirect heat <span class="hlt">exchange</span> with the formed hydrogen rich <span class="hlt">gas</span>, igniting the hydrocarbon fuel spray mixed with the preheated mixture of steam and air within the partial oxidation region to form a hydrogen rich <span class="hlt">gas</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1980JChPh..72.5223R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1980JChPh..72.5223R"><span>Comparison of local <span class="hlt">exchange</span> potentials of electron-N2 scattering</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rumble, J. R., Jr.; Truhlar, D. G.</p> <p>1980-05-01</p> <p>Vibrationally and electronically elastic electron scattering by N2 at 2-30 eV impact energy is considered. Static, static-<span class="hlt">exchange</span>, and static-<span class="hlt">exchange</span>-plus-polarization potentials, Cade-Sales-Wahl and INDO/1s wave functions, and semiclassical <span class="hlt">exchange</span> and Hara free-electron-<span class="hlt">gas</span> <span class="hlt">exchange</span> potentials are examined. It is shown that the semiclassical <span class="hlt">exchange</span> approximation is too attractive at low energy for N2. It is also shown quantitatively by consideration of partial and total integral cross sections how the effects of approximations to <span class="hlt">exchange</span> become smaller as the incident energy is increased until the differences are about 8% for the total integral cross section at 30 eV.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JEMat..39.1463M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JEMat..39.1463M"><span>Optimization of the Heat <span class="hlt">Exchangers</span> of a Thermoelectric Generation System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martínez, A.; Vián, J. G.; Astrain, D.; Rodríguez, A.; Berrio, I.</p> <p>2010-09-01</p> <p>The thermal resistances of the heat <span class="hlt">exchangers</span> have a strong influence on the electric power produced by a thermoelectric generator. In this work, the heat <span class="hlt">exchangers</span> of a thermoelectric generator have been optimized in order to maximize the electric power generated. This thermoelectric generator harnesses heat from the exhaust <span class="hlt">gas</span> of a domestic <span class="hlt">gas</span> boiler. Statistical design of experiments was used to assess the influence of five factors on both the electric power generated and the pressure drop in the chimney: height of the generator, number of modules per meter of generator height, length of the fins of the hot-side heat <span class="hlt">exchanger</span> (HSHE), length of the gap between fins of the HSHE, and base thickness of the HSHE. The electric power has been calculated using a computational model, whereas Fluent computational fluid dynamics (CFD) has been used to obtain the thermal resistances of the heat <span class="hlt">exchangers</span> and the pressure drop. Finally, the thermoelectric generator has been optimized, taking into account the restrictions on the pressure drop.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986JGR....9112327M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986JGR....9112327M"><span>Advances in soil <span class="hlt">gas</span> geochemical exploration for natural resources: Some current examples and practices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McCarthy, J. Howard, Jr.; Reimer, G. Michael</p> <p>1986-11-01</p> <p>Field studies have demonstrated that <span class="hlt">gas</span> anomalies are found over buried mineral deposits. <span class="hlt">Abnormally</span> high concentrations of sulfur gases and carbon dioxide and <span class="hlt">abnormally</span> low concentrations of oxygen are commonly found over sulfide ore deposits. Helium anomalies are commonly associated with uranium deposits and geothermal areas. Helium and hydrocarbon <span class="hlt">gas</span> anomalies have been detected over oil and <span class="hlt">gas</span> deposits. Gases are sampled by extracting them from the pore space of soil, by degassing soil or rock, or by adsorbing them on artificial collectors. The two most widely used techniques for <span class="hlt">gas</span> analysis are <span class="hlt">gas</span> chromatography and mass spectrometry. The detection of <span class="hlt">gas</span> anomalies at or near the surface may be an effective method to locate buried mineral deposits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/203613-gaseous-exchange-polycyclic-aromatic-hydrocarbons-across-air-water-interface-lower-chesapeake-bay','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/203613-gaseous-exchange-polycyclic-aromatic-hydrocarbons-across-air-water-interface-lower-chesapeake-bay"><span>Gaseous <span class="hlt">exchange</span> of polycyclic aromatic hydrocarbons across the air-water interface of lower Chesapeake Bay</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Gustafson, K.E.; Dickhut, R.M.</p> <p>1995-12-31</p> <p>The gaseous <span class="hlt">exchange</span> fluxes of polycyclic aromatic hydrocarbons (PAHs) across the air-water interface of lower Chesapeake Bay were determined using a modified two-film <span class="hlt">exchange</span> model. Sampling covered the period January 1994 to June 1995 for five sites on lower Chesapeake Bay ranging from rural to urban and highly industrialized. Simultaneous air and water samples were collected and the atmospheric <span class="hlt">gas</span> phase and water column dissolved phase analyzed via GC/MS for 17 PAHs. The direction and magnitude of flux for each PAH was calculated using Henry`s law constants, hydrological and meteorological parameters, Temperature was observed to be an important environmental factormore » in determining both the direction and magnitude of PAH <span class="hlt">gas</span> <span class="hlt">exchange</span>. Nonetheless, wind speed significantly impacts mass transfer coefficients, and therefore was found to control the magnitude of flux. Spatial and temporal variation of PAH gaseous <span class="hlt">exchange</span> fluxes were examined. Fluxes were determined to be both into and out of Chesapeake Bay. The range of <span class="hlt">gas</span> <span class="hlt">exchange</span> fluxes ({minus}560 to 600{micro}g/M{sup 2}*Mo) is of the same order to 10X greater than atmospheric wet and dry depositional fluxes to lower Chesapeake Bay. The results of this study support the hypothesis that <span class="hlt">gas</span> <span class="hlt">exchange</span> is a major transport process affecting the net loadings of PAHs in lower Chesapeake Bay.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1562445','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1562445"><span>Effect of heat and moisture <span class="hlt">exchanger</span> (HME) positioning on inspiratory <span class="hlt">gas</span> humidification</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Inui, Daisuke; Oto, Jun; Nishimura, Masaji</p> <p>2006-01-01</p> <p>Background In mechanically ventilated patients, we investigated how positioning the heat and moisture <span class="hlt">exchanger</span> (HME) at different places on the ventilator circuit affected inspiratory <span class="hlt">gas</span> humidification. Methods Absolute humidity (AH) and temperature (TEMP) at the proximal end of endotracheal tube (ETT) were measured in ten mechanically ventilated patients. The HME was connected either directly proximal to the ETT (Site 1) or at before the circuit Y-piece (Site 2: distance from proximal end of ETT and Site 2 was about 19 cm) (Figure. 1). Two devices, Hygrobac S (Mallinckrodt Dar, Mirandola, Italy) and Thermovent HEPA (Smiths Medical International Ltd., Kent, UK) were tested. AH and TEMP were measured with a hygrometer (Moiscope, MERA Co., Ltd., Tokyo, Japan). Results Hygrobac S provided significantly higher AH and TEMP at both sites than Thermovent HEPA. Both Hygrobac S and with Thermovent HEPA provided significantly higher AH and TEMP when placed proximally to the ETT. Conclusion Although placement proximal to the ETT improved both AH and TEMP in both HMEs tested, one HME performed better in the distal position than the other HME in the proximal position. We conclude the both the type and placement of HME can make a significant difference in maintaining AH and TEMP during adult ventilation. PMID:16895607</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <div class="footer-extlink text-muted" style="margin-bottom:1rem; text-align:center;">Some links on this page may take you to non-federal websites. 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