Pulmonary function abnormalities in never-smoking flight attendants exposed to secondhand tobacco smoke in the aircraft cabin.

PubMed

Arjomandi, Mehrdad; Haight, Thaddeus; Redberg, Rita; Gold, Warren M

2009-06-01

To determine whether the flight attendants who were exposed to secondhand tobacco smoke in the aircraft cabin have abnormal pulmonary function. We administered questionnaires and performed pulmonary function testing in 61 never-smoking female flight attendants who worked in active air crews before the smoking ban on commercial aircraft (preban). Although the preban flight attendants had normal FVC, FEV1, and FEV1/FVC ratio, they had significantly decreased flow at mid- and low-lung volumes, curvilinear flow-volume curves, and evidence of air trapping. Furthermore, the flight attendants had significantly decreased diffusing capacity (77.5% +/- 11.2% predicted normal) with 51% having a diffusing capacity below their 95% normal prediction limit. This cohort of healthy never-smoking flight attendants who were exposed to secondhand tobacco smoke in the aircraft cabin showed pulmonary function abnormalities suggestive of airway obstruction and impaired diffusion.

Tidal volume single-breath washin of SF6 and CH4 in transient microgravity

NASA Technical Reports Server (NTRS)

Dutrieue, Brigitte; Paiva, Manuel; Verbanck, Sylvia; Le Gouic, Marine; Darquenne, Chantal; Prisk, G. Kim

2003-01-01

We performed tidal volume single-breath washins (SBW) by using tracers of different diffusivity and varied the time spent in microgravity (microG) before the start of the tests to look for time-dependent effects. SF(6) and CH(4) phase III slopes decreased by 35 and 26%, respectively, in microG compared with 1 G (P < 0.05), and the slope difference between gases disappeared. There was no effect of time in microG, suggesting that neither the hypergravity period preceding microG nor the time spent in microG affected gas mixing at volumes near functional residual capacity. In previous studies using SF(6) and He (Lauzon A-M, Prisk GK, Elliott AR, Verbanck S, Paiva M, and West JB. J Appl Physiol 82: 859-865, 1997), the vital capacity SBW showed an increase in slope difference between gases in transient microG, the opposite of the decrease in sustained microG. In contrast, tidal volume SBW showed a decrease in slope difference in both microG conditions. Because it is only the behavior of the more diffusive gas that differed between maneuvers and microG conditions, we speculate that, in the previous vital capacity SBW, the hypergravity period preceding the test in transient microG provoked conformational changes at low lung volumes near the acinar entrance.

Pulmonary function of nonsmoking female asbestos workers without radiographic signs of asbestosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, X.R.; Yano, E.; Nonaka, Koichi

Researchers disagree about whether exposure to asbestos causes significant respiratory impairments and airway obstruction in the absence of radiographic asbestosis and smoking. To obtain confirmatory information, the authors examined pulmonary function of 208 nonsmoking female asbestos workers who did not have asbestosis and 136 controls. The authors observed an overall lower single-breath carbon monoxide diffusing capacity in the asbestos workers than in controls. In addition, significant decreases in percentage vital capacity, percentage forced vital capacity, and percentage mean forced expiratory flow during the middle half of the forced vital capacity were evident in the older workers. Logistic regression analysis revealedmore » that asbestos exposure was associated with abnormal single-breath carbon monoxide diffusing capacity, vital capacity, and mean forced expiratory flow during the middle half of the forced vital capacity among the older workers. The age-related decline in vital capacity, forced vital capacity, and mean forced expiratory flow during the middle half of the forced vital capacity was significantly greater in the asbestos workers than the controls. The findings imply that asbestos-exposure per se contributes predominantly to restricted lung volume and reduced single-breath carbon monoxide diffusing capacity. Asbestos may also cause slight airway obstruction, especially in workers who are heavily exposed.« less

Periodontitis is related to lung volumes and airflow limitation: a cross-sectional study.

PubMed

Holtfreter, Birte; Richter, Stefanie; Kocher, Thomas; Dörr, Marcus; Völzke, Henry; Ittermann, Till; Obst, Anne; Schäper, Christoph; John, Ulrich; Meisel, Peter; Grotevendt, Anne; Felix, Stephan B; Ewert, Ralf; Gläser, Sven

2013-12-01

This study aimed to assess the potential association of periodontal diseases with lung volumes and airflow limitation in a general adult population. Based on a representative population sample of the Study of Health in Pomerania (SHIP), 1463 subjects aged 25-86 years were included. Periodontal status was assessed by clinical attachment loss (CAL), probing depth and number of missing teeth. Lung function was measured using spirometry, body plethysmography and diffusing capacity of the lung for carbon monoxide. Linear regression models using fractional polynomials were used to assess associations between periodontal disease and lung function. Fibrinogen and high-sensitivity C-reactive protein (hs-CRP) were evaluated as potential intermediate factors. After full adjustment for potential confounders mean CAL was significantly associated with variables of mobile dynamic and static lung volumes, airflow limitation and hyperinflation (p<0.05). Including fibrinogen and hs-CRP did not change coefficients of mean CAL; associations remained statistically significant. Mean CAL was not associated with total lung capacity and diffusing capacity of the lung for carbon monoxide. Associations were confirmed for mean probing depth, extent measures of CAL/probing depth and number of missing teeth. Periodontal disease was significantly associated with reduced lung volumes and airflow limitation in this general adult population sample. Systemic inflammation did not provide a mechanism linking both diseases.

Thermophysical properties of heat-treated U-7Mo/Al dispersion fuel

NASA Astrophysics Data System (ADS)

Cho, Tae Won; Kim, Yeon Soo; Park, Jong Man; Lee, Kyu Hong; Kim, Sunghwan; Lee, Chong Tak; Yang, Jae Ho; Oh, Jang Soo; Sohn, Dong-Seong

2018-04-01

In this study, the effects of interaction layer (IL) on thermophysical properties of U-7Mo/Al dispersion fuel were examined. Microstructural analyses revealed that ILs were formed uniformly on U-Mo particles during heating of U-7Mo/Al samples. The IL volume fraction was measured by applying image analysis methods. The uranium loadings of the samples were calculated based on the measured meat densities at 298 K. The density of the IL was estimated by using the measured density and IL volume fraction. Thermal diffusivity and heat capacity of the samples after the heat treatment were measured as a function of temperature and volume fractions of U-Mo and IL. The thermal conductivity of IL-formed U-7Mo/Al was derived by using the measured thermal diffusivity, heat capacity, and density. The thermal conductivity obtained in the present study was lower than that predicted by the modified Hashin-Shtrikman model due to the theoretical model's inability to consider the thermal resistance at interfaces between the meat constituents.

Thermodynamic properties and diffusion of water + methane binary mixtures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shvab, I.; Sadus, Richard J., E-mail: rsadus@swin.edu.au

2014-03-14

Thermodynamic and diffusion properties of water + methane mixtures in a single liquid phase are studied using NVT molecular dynamics. An extensive comparison is reported for the thermal pressure coefficient, compressibilities, expansion coefficients, heat capacities, Joule-Thomson coefficient, zero frequency speed of sound, and diffusion coefficient at methane concentrations up to 15% in the temperature range of 298–650 K. The simulations reveal a complex concentration dependence of the thermodynamic properties of water + methane mixtures. The compressibilities, heat capacities, and diffusion coefficients decrease with increasing methane concentration, whereas values of the thermal expansion coefficients and speed of sound increase. Increasing methanemore » concentration considerably retards the self-diffusion of both water and methane in the mixture. These effects are caused by changes in hydrogen bond network, solvation shell structure, and dynamics of water molecules induced by the solvation of methane at constant volume conditions.« less

Interconnected silicon hollow nanospheres for lithium-ion battery anodes with long cycle life.

PubMed

Yao, Yan; McDowell, Matthew T; Ryu, Ill; Wu, Hui; Liu, Nian; Hu, Liangbing; Nix, William D; Cui, Yi

2011-07-13

Silicon is a promising candidate for the anode material in lithium-ion batteries due to its high theoretical specific capacity. However, volume changes during cycling cause pulverization and capacity fade, and improving cycle life is a major research challenge. Here, we report a novel interconnected Si hollow nanosphere electrode that is capable of accommodating large volume changes without pulverization during cycling. We achieved the high initial discharge capacity of 2725 mAh g(-1) with less than 8% capacity degradation every hundred cycles for 700 total cycles. Si hollow sphere electrodes also show a Coulombic efficiency of 99.5% in later cycles. Superior rate capability is demonstrated and attributed to fast lithium diffusion in the interconnected Si hollow structure.

Ab initio study of novel carbon nanofoam structure as an anode material for Li secondary battery

NASA Astrophysics Data System (ADS)

Park, Hanjin; Park, Sora; Kang, Seoung-Hun; Kwon, Young-Kyun

2014-03-01

Using ab inito density functional theory, we investigate the adsorption and diffusion properties of Li atoms on a new carbon nanostructure, which may be used as an anode of Li secondary battery. We focus on a special carbon nanofoam structure consisting of Schwarzite structures with negative Gaussian curvature as core parts, which are interconnected through (4,4) CNT segments. Considering the symmetry of the nanofoam structure, we find various Li adsorption sites exhibiting relatively large binding energies (>= 2 . 00 eV). Based on these adsorption sites, we identify several diffusion paths on the outside or inside surface of the nanofoam structure and examine the diffusion barriers along the paths. Our results show that Li atom can diffuse almost freely due to its low energy barriers on both outside and inside surfaces. Finally, we also evaluate the energy gain tendency and the volume expansion as well as the average binding energy while adding Li atoms to estimate the Li-capacity and recyclability of the system, which are important characterisitics for anode materials. We conclude that the carbon nanofoam structure would be better as an anode material than graphite in Li capacity and volume expansion.

Enhanced alveolar growth and remodeling in Guinea pigs raised at high altitude.

PubMed

Hsia, Connie C W; Carbayo, Juan J Polo; Yan, Xiao; Bellotto, Dennis J

2005-05-12

To examine the effects of chronic high altitude (HA) exposure on lung structure during somatic maturation, we raised male weanling guinea pigs at HA (3800m) for 1, 3, or 6 months, while their respective male littermates were simultaneously raised at low altitude (LA, 1200m). Under anaesthesia, airway pressure was measured at different lung volumes. The right lung was fixed at a constant airway pressure for morphometric analysis under light and electron microscopy. In animals raised at HA for 1 month, lung volume, alveolar surface area and alveolar-capillary blood volume (V(c)) were elevated above LA control values. Following 3-6 months of HA exposure, increases in lung volume and alveolar surface area persisted while the initial increase in V(c) normalized. Additional adaptation occurred, including a higher epithelial cell volume, septal tissue volume and capillary surface area, a lower alveolar duct volume and lower harmonic mean diffusion barrier resulting in higher membrane and lung diffusing capacities. These data demonstrate enhanced alveolar septal growth and progressive acinar remodeling during chronic HA exposure with long-term augmentation of alveolar dimensions as well as functional compensation in lung compliance and diffusive gas transport.

[Interpretation and use of routine pulmonary function tests: Spirometry, static lung volumes, lung diffusion, arterial blood gas, methacholine challenge test and 6-minute walk test].

PubMed

Bokov, P; Delclaux, C

2016-02-01

Resting pulmonary function tests (PFT) include the assessment of ventilatory capacity: spirometry (forced expiratory flows and mobilisable volumes) and static volume assessment, notably using body plethysmography. Spirometry allows the potential definition of obstructive defect, while static volume assessment allows the potential definition of restrictive defect (decrease in total lung capacity) and thoracic hyperinflation (increase in static volumes). It must be kept in mind that this evaluation is incomplete and that an assessment of ventilatory demand is often warranted, especially when facing dyspnoea: evaluation of arterial blood gas (searching for respiratory insufficiency) and measurement of the transfer coefficient of the lung, allowing with the measurement of alveolar volume to calculate the diffusing capacity of the lung for CO (DLCO: assessment of alveolar-capillary wall and capillary blood volume). All these pulmonary function tests have been the subject of an Americano-European Task force (standardisation of lung function testing) published in 2005, and translated in French in 2007. Interpretative strategies for lung function tests have been recommended, which define abnormal lung function tests using the 5th and 95th percentiles of predicted values (lower and upper limits of normal values). Thus, these recommendations need to be implemented in all pulmonary function test units. A methacholine challenge test will only be performed in the presence of an intermediate pre-test probability for asthma (diagnostic uncertainty), which is an infrequent setting. The most convenient exertional test is the 6-minute walk test that allows the assessment of walking performance, the search for arterial desaturation and the quantification of dyspnoea complaint. Copyright © 2015 Société nationale française de médecine interne (SNFMI). Published by Elsevier SAS. All rights reserved.

Video-assisted thoracoscopic bullectomy and talc poudrage for spontaneous pneumothoraces: effect on short-term lung function.

PubMed

Dubois, Luc; Malthaner, Richard A

2010-12-01

We measured lung function before and after video-assisted thoracoscopic apical bullectomy and talc poudrage in patients with spontaneous pneumothoraces. Seventy-two patients were prospectively followed up for 12 months. The indications for surgery were recurrent pneumothoraces (n = 58), bilateral pneumothoraces (n = 8), and persistent air leak (n = 6). There were 46 males and 26 females with mean age of 29 years (range 15-61 years). The results were analyzed using paired t tests. There were no recurrences. There were 4 complications (5.6%): 1 wound infection, 1 case of pneumonia, and 2 persistent air leaks each lasting 1 week. There were no conversions to open surgery. Preoperative and 6-month pulmonary function test results were available on 41 patients, and 35 patients completed 12-month pulmonary function tests. Twelve-month values (mean percent ± SD) were as follows: Forced expiratory volume in 1 second fell from 95 ± 19 to 89 ± 16 (P = .02); forced expiratory volume in 1 second/forced vital capacity ratio was unchanged, 95 ± 12 versus 94 ± 13 (P = .9); total lung capacity fell from 106 ± 19 to 98 ± 12 (P = 0.002); vital capacity fell from 100 ± 22 to 96 ± 16 (P = .05); residual volume fell from 126 ± 32 to 107 ± 29 (P = .002); and diffusion capacity for carbon monoxide corrected for alveolar volume was unchanged, 88 ± 15 versus 91 ± 17 (P = .07). Flow rates and diffusion capacities were preserved, but lung volumes were slightly reduced at 1 year. Video-assisted thoracoscopic apical bullectomy and talc poudrage is an effective treatment for spontaneous pneumothoraces with a low complication rate and recurrence rate and only minor changes in pulmonary function at 1 year. Copyright © 2010 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Contribution of CT quantified emphysema, air trapping and airway wall thickness on pulmonary function in male smokers with and without COPD.

PubMed

Mohamed Hoesein, Firdaus A A; de Jong, Pim A; Lammers, Jan-Willem J; Mali, Willem P Th M; Mets, Onno M; Schmidt, Michael; de Koning, Harry J; Aalst, Carlijn van der; Oudkerk, Matthijs; Vliegenthart, Rozemarijn; Ginneken, Bram van; van Rikxoort, Eva M; Zanen, Pieter

2014-09-01

Emphysema, airway wall thickening and air trapping are associated with chronic obstructive pulmonary disease (COPD). All three can be quantified by computed tomography (CT) of the chest. The goal of the current study is to determine the relative contribution of CT derived parameters on spirometry, lung volume and lung diffusion testing. Emphysema, airway wall thickening and air trapping were quantified automatically on CT in 1,138 male smokers with and without COPD. Emphysema was quantified by the percentage of voxels below -950 Hounsfield Units (HU), airway wall thickness by the square root of wall area for a theoretical airway with 10 mm lumen perimeter (Pi10) and air trapping by the ratio of mean lung density at expiration and inspiration (E/I-ratio). Spirometry, residual volume to total lung capacity (RV/TLC) and diffusion capacity (Kco) were obtained. Standardized regression coefficients (β) were used to analyze the relative contribution of CT changes to pulmonary function measures. The independent contribution of the three CT measures differed per lung function parameter. For the FEV1 airway wall thickness was the most contributing structural lung change (β = -0.46), while for the FEV1/FVC this was emphysema (β = -0.55). For the residual volume (RV) air trapping was most contributing (β = -0.35). Lung diffusion capacity was most influenced by emphysema (β = -0.42). In a cohort of smokers with and without COPD the effect of different CT changes varies per lung function measure and therefore emphysema, airway wall thickness and air trapping need to be taken in account.

Retinoic acid-induced alveolar cellular growth does not improve function after right pneumonectomy.

PubMed

Dane, D Merrill; Yan, Xiao; Tamhane, Rahul M; Johnson, Robert L; Estrera, Aaron S; Hogg, Deborah C; Hogg, Richard T; Hsia, Connie C W

2004-03-01

To determine whether all-trans retinoic acid (RA) treatment enhances lung function during compensatory lung growth in fully mature animals, adult male dogs (n = 4) received 2 mg x kg(-1) x day(-1) po RA 4 days/wk beginning the day after right pneumonectomy (R-PNX, 55-58% resection). Litter-matched male R-PNX controls (n = 4) received placebo. After 3 mo, transpulmonary pressure (TPP)-lung volume relationship, diffusing capacities for carbon monoxide and nitric oxide, cardiac output, and septal volume (V(tiss-RB)) were measured under anesthesia by a rebreathing technique at two lung volumes. Lung air and tissue volumes (V(air-CT) and V(tiss-CT)) were also measured from high-resolution computerized tomographic (CT) scans at a constant TPP. In RA-treated dogs compared with controls, TPP-lung volume relationships were similar. Diffusing capacities for carbon monoxide and nitric oxide were significantly impaired at a lower lung volume but similar at a high lung volume. Whereas V(tiss-RB) was significantly lower at both lung volumes in RA-treated animals, V(air-CT) and V(tiss-CT) were not different between groups; results suggest uneven distribution of ventilation consistent with distortion of alveolar geometry and/or altered small airway function induced by RA. We conclude that RA does not improve resting pulmonary function during the early months after R-PNX despite histological evidence of its action in enhancing alveolar cellular growth in the remaining lung.

Thermophysical properties of heat-treated U-7Mo/Al dispersion fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, Tae Won; Kim, Yeon Soo; Park, Jong Man

In this study, the effects of interaction layer (IL) on thermophysical properties of U-7Mo/Al dispersion fuel were examined. Microstructural analyses revealed that ILs were formed uniformly on U-Mo particles during heating of U-7Mo/Al samples. The IL volume fraction was measured by applying image analysis methods. The uranium loadings of the samples were calculated based on the measured meat densities at 298 K. The density of the IL was estimated by using the measured density and IL volume fraction. Thermal diffusivity and heat capacity of the samples after the heat treatment were measured as a function of temperature and volume fractionsmore » of U-Mo and IL. The thermal conductivity of IL-formed U-7Mo/Al was derived by using the measured thermal diffusivity, heat capacity, and density. The thermal conductivity obtained in the present study was lower than that predicted by the modified Hashin–Shtrikman model due to the theoretical model’s inability to consider the thermal resistance at interfaces between the meat constituents.« less

On the contribution of height to predict lung volumes, capacities and diffusion in healthy school children of 10-17 years.

PubMed

Gupta, C K; Mishra, G; Mehta, S C; Prasad, J

1993-01-01

Lung volumes, capacities, diffusion and alveolar volumes with physical characteristics (age, height and weight) were recorded for 186 healthy school children (96 boys and 90 girls) of 10-17 years age group. The objective was to study the relative importance of physical characteristics as regressor variables in regression models to estimate lung functions. We observed that height is best correlated with all the lung functions. Inclusion of all physical characteristics in the models have little gain compared to the ones having just height as regressor variable. We also find that exponential models were not only statistically valid but fared better compared to the linear ones. We conclude that lung functions covary with height and other physical characteristics but do not depend upon them. The rate of increase in the functions depend upon initial lung functions. Further, we propose models and provide ready reckoners to give estimates of lung functions with 95 per cent confidence limits based on heights from 125 to 170 cm for the age group of 10 to 17 years.

The large lungs of elite swimmers: an increased alveolar number?

PubMed

Armour, J; Donnelly, P M; Bye, P T

1993-02-01

In order to obtain further insight into the mechanisms relating to the large lung volumes of swimmers, tests of mechanical lung function, including lung distensibility (K) and elastic recoil, pulmonary diffusion capacity, and respiratory mouth pressures, together with anthropometric data (height, weight, body surface area, chest width, depth and surface area), were compared in eight elite male swimmers, eight elite male long distance athletes and eight control subjects. The differences in training profiles of each group were also examined. There was no significant difference in height between the subjects, but the swimmers were younger than both the runners and controls, and both the swimmers and controls were heavier than the runners. Of all the training variables, only the mean total distance in kilometers covered per week was significantly greater in the runners. Whether based on: (a) adolescent predicted values; or (b) adult male predicted values, swimmers had significantly increased total lung capacity ((a) 145 +/- 22%, (mean +/- SD) (b) 128 +/- 15%); vital capacity ((a) 146 +/- 24%, (b) 124 +/- 15%); and inspiratory capacity ((a) 155 +/- 33%, (b) 138 +/- 29%), but this was not found in the other two groups. Swimmers also had the largest chest surface area and chest width. Forced expiratory volume in one second (FEV1) was largest in the swimmers ((b) 122 +/- 17%) and FEV1 as a percentage of forced vital capacity (FEV1/FVC)% was similar for the three groups. Pulmonary diffusing capacity (DLCO) was also highest in the swimmers (117 +/- 18%). All of the other indices of lung function, including pulmonary distensibility (K), elastic recoil and diffusion coefficient (KCO), were similar. These findings suggest that swimmers may have achieved greater lung volumes than either runners or control subjects, not because of greater inspiratory muscle strength, or differences in height, fat free mass, alveolar distensibility, age at start of training or sternal length or chest depth, but by developing physically wider chests, containing an increased number of alveoli, rather than alveoli of increased size. However, in this cross-sectional study, hereditary factors cannot be ruled out, although we believe them to be less likely.

Si/Ge double-layered nanotube array as a lithium ion battery anode.

PubMed

Song, Taeseup; Cheng, Huanyu; Choi, Heechae; Lee, Jin-Hyon; Han, Hyungkyu; Lee, Dong Hyun; Yoo, Dong Su; Kwon, Moon-Seok; Choi, Jae-Man; Doo, Seok Gwang; Chang, Hyuk; Xiao, Jianliang; Huang, Yonggang; Park, Won Il; Chung, Yong-Chae; Kim, Hansu; Rogers, John A; Paik, Ungyu

2012-01-24

Problems related to tremendous volume changes associated with cycling and the low electron conductivity and ion diffusivity of Si represent major obstacles to its use in high-capacity anodes for lithium ion batteries. We have developed a group IVA based nanotube heterostructure array, consisting of a high-capacity Si inner layer and a highly conductive Ge outer layer, to yield both favorable mechanics and kinetics in battery applications. This type of Si/Ge double-layered nanotube array electrode exhibits improved electrochemical performances over the analogous homogeneous Si system, including stable capacity retention (85% after 50 cycles) and doubled capacity at a 3C rate. These results stem from reduced maximum hoop strain in the nanotubes, supported by theoretical mechanics modeling, and lowered activation energy barrier for Li diffusion. This electrode technology creates opportunities in the development of group IVA nanotube heterostructures for next generation lithium ion batteries. © 2011 American Chemical Society

Caramel popcorn shaped silicon particle with carbon coating as a high performance anode material for Li-ion batteries.

PubMed

He, Meinan; Sa, Qina; Liu, Gao; Wang, Yan

2013-11-13

Silicon is a very promising anode material for lithium ion batteries. It has a 4200 mAh/g theoretical capacity, which is ten times higher than that of commercial graphite anodes. However, when lithium ions diffuse to Si anodes, the volume of Si will expand to almost 400% of its initial size and lead to the crack of Si. Such a huge volume change and crack cause significant capacity loss. Meanwhile, with the crack of Si particles, the conductivity between the electrode and the current collector drops. Moreover, the solid electrolyte interphase (SEI), which is generated during the cycling, reduces the discharge capacity. These issues must be addressed for widespread application of this material. In this work, caramel popcorn shaped porous silicon particles with carbon coating are fabricated by a set of simple chemical methods as active anode material. Si particles are etched to form a porous structure. The pores in Si provide space for the volume expansion and liquid electrolyte diffusion. A layer of amorphous carbon is formed inside the pores, which gives an excellent isolation between the Si particle and electrolyte, so that the formation of the SEI layer is stabilized. Meanwhile, this novel structure enhances the mechanical properties of the Si particles, and the crack phenomenon caused by the volume change is significantly restrained. Therefore, an excellent cycle life under a high rate for the novel Si electrode is achieved.

Extended dynamic model for ion diffusion in all-vanadium redox flow battery including the effects of temperature and bulk electrolyte transfer

NASA Astrophysics Data System (ADS)

Badrinarayanan, Rajagopalan; Zhao, Jiyun; Tseng, K. J.; Skyllas-Kazacos, Maria

2014-12-01

As with all redox flow batteries, the Vanadium Redox flow Battery (VRB) can suffer from capacity loss as the vanadium ions diffuse at different rates leading to a build-up on one half-cell and dilution on the other. In this paper an extended dynamic model of the vanadium ion transfer is developed including the effect of temperature and bulk electrolyte transfer. The model is used to simulate capacity decay for a range of different ion exchange membranes that are being used in the VRB. The simulations show that Selemion CMV and Nafion 115 membranes have similar behavior where the impact of temperature on capacity loss is highest within the first 100 cycles. The results for Selemion AMV membrane however are seen to be very different where the capacity loss at different temperatures observed to increase linearly with increasing charging/discharging cycles. The model is made more comprehensive by including the effect of bulk electrolyte transfer. A volume change of 19% is observed in each half-cell for Nafion 115 membrane based on the simulation parameters. The effect of this change in volume directly affects concentration, and the characteristics are analyzed for each vanadium species as well as the overall concentration in the half-cells.

Acute changes in lung function associated with proximity to a steel plant: a randomized study.

PubMed

Dales, Robert; Kauri, Lisa Marie; Cakmak, Sabit; Mahmud, Mamun; Weichenthal, Scott A; Van Ryswyk, Keith; Kumarathasan, Premkumari; Thomson, Errol; Vincent, Renaud; Broad, Gayle; Liu, Ling

2013-05-01

Steel production is a major industry worldwide yet there is relatively little information on the pulmonary effects of air quality near steel manufacturing plants. The aim of this study was to examine how lung function changes acutely when healthy subjects are situated near a steel plant which is adjacent to a residential area. Sixty-one subjects were randomly assigned to spend 5 consecutive, 8-hour days in a residential neighborhood approximately 0.9km from a steel plant, or approximately 4.5km away at a college campus. Subjects crossed-over between sites after a nine-day washout period. Lung function was measured daily at both sites along with air pollutants including SO2, NO2, O3, PM2.5, and ultrafine particles. Diffusion capacity and pulse oximetry were also examined. Compared with the college site, the forced expiratory volume in 1-second/forced vital capacity, forced expiratory flow between 25% and 75% of the FVC, total lung capacity, functional residual capacity, and residual volume were lower near the steel plant by 0.67% (95% CI: 0.28, 1.06),1.62% (95% CI: 0.50, 2.75), 1.54% (95% CI: 0.68, 2.39), 3.54% (95% CI: 1.95, 5.13) and 11.3% (95% CI: 4.92, 17.75), respectively. Diffusion capacity, forced expiratory volume in 1s, and pulse oximetry were also lower near the plant but these effects were not statistically significant. Sulfur dioxide, ultrafine particulates, and oxides of nitrogen were greater near the steel plant site compared to the college site. Spending short periods of time near a steel plant is associated with a decrease in lung function. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

[Lung volume reduction surgery for severe pulmonary emphysema in Iceland].

PubMed

Gunnarsson, Sverrir I; Johannsson, Kristinn B; Guðjónsdóttir, Marta; Jónsson, Steinn; Beck, Hans J; Magnusson, Bjorn; Gudbjartsson, Tomas

2011-12-01

Lung volume reduction surgery (LVRS) can benefit patients with severe emphysema. The aim of this study was to evaluate the outcome of LVRS performed in Iceland. A prospective study of 16 consecutive patients who underwent bilateral LVRS through median sternotomy between January 1996 and December 2008. All patients had disabling dyspnea, lung hyperinflation, and emphysema with upper lobe predominance. Preoperatively all patients underwent pulmonary rehabilitation. Spirometry, lung volumes, arterial blood gases and exercise capacity were measured before and after surgery. Mean follow-up time was 8.7 years. Mean age was 59.2 ± 5.9 years. All patients had a history of heavy smoking. There was no perioperative mortality and survival was 100%, 93%, and 63% at 1, 5, and 10 years, respectively. The forced expiratory volume in 1 second (FEV1) and the forced vital capacity (FVC) improved significantly after surgery by 35% (p<0.001) and 14% (p<0.05), respectively. The total lung capacity, residual volume and partial pressure of CO2 also showed statistically significant improvements but exercise capacity, O2 consumption and diffusing capacity of the lung for CO did not change. Prolonged air leak (≥ 7 days) was the most common complication (n=7). Five patients required reoperation, most commonly for sternal dehiscence (n=4). In this small prospective study, FEV1 and FVC increased and lung volumes and PaCO2 improved after LVRS. Long term survival was satisfactory although complications such as reoperations for sternal dehiscence were common and hospital stay therefore often prolonged.

Functional capacities of lungs and thorax in beagles after prolonged residence at 3,100 m.

PubMed

Johnson, R L; Cassidy, S S; Grover, R F; Schutte, J E; Epstein, R H

1985-12-01

Functional capacities of the lungs and thorax in beagles taken to high altitude as adults for 33 mo or in beagles raised from puppies at high altitude were compared with functional capacities in corresponding sets of beagles kept simultaneously at sea level. Comparisons were made after reacclimatization to sea level. Lung volumes, airway pressures, esophageal pressures, CO diffusing capacities (DLCO), pulmonary blood flow, and lung tissue volume (Vt) were measured by a rebreathing technique at inspired volumes ranging from 15 to 90 ml/kg. In beagles raised from puppies we measured anatomical distribution of intrathoracic air and tissue using X-ray computed tomography at transpulmonary pressures of 20 cm H2O. Lung and thoracic distensibility, DLCO, and Vt were not different between beagles that had been kept at high altitude for 33 mo as adults and control subjects kept simultaneously at sea level. Lung distensibility, DLCO, and Vt were significantly greater in beagles raised at high altitude than control subjects raised simultaneously at sea level. Thoracic distensibility was not increased in beagles raised at high altitude; the larger lung volume was accommodated by a lower diaphragm, not a larger rib cage.

The Role of the Army in Infrastructure and Capacity Building

DTIC Science & Technology

2010-02-01

Issues Volume I: Theory of War and Strategy 3rd edition, ed. J. Boone Bartholomees, Jr. (Carlisle: USAWC Strategic Studies Institute, 2009), 145...efforts. 34 Raj M. Desai and Homi Kharas, Do Philanthropic Citizens Behave Like Governments? Internet-Based Platforms and the Diffusion of International

The respiratory system under weightlessness

NASA Technical Reports Server (NTRS)

Paiva, M.; Engel, L. A.; Hughes, J. M. B.; Guy, H. J.; Prisk, G. K.; West, J. B.

1987-01-01

Studies of pulmonary functions at rest to be studied on Spacelab mission D-2 are introduced. Gravity dependence of the distribution of ventilation (single breath washout, multibreath washout-washin); chest wall shape and motion; and the vascular compartment (lung blood flow, capillary volume, liquid content, diffusive capacity) are discussed.

Postural variation of pulmonary diffusing capacity as a marker of lung microangiopathy in Indian patients with type 2 diabetes mellitus.

PubMed

Kumar, Avinash; Bade, Geetanjali; Trivedi, Anjali; Jyotsna, Viveka P; Talwar, Anjana

2016-01-01

Diabetes mellitus (DM) is characterized by the presence of chronic hyperglycemia and formation of advanced glycation end products (AGEs). Interaction between AGE and its receptor leads to endothelial damage and microangiopathy. This study was undertaken to investigate the possibility of using a postural variation of diffusing capacity as an early marker of lung microangiopathy and its correlation with the level of adhesion molecules, HbA1c, duration of diabetes, and insulin resistance in type 2 DM (T2DM) patients with and without microangiopathy. Forty patients having T2DM without any microangiopathy (n = 20) as well as with microangiopathy (n = 20), and 22 age and sex matched healthy controls were enrolled in this cross-sectional study. Measurement of lung volumes and capacities were done. DLco was measured in sitting and supine position. Levels of vascular cell adhesion molecule-1 (VCAM-1), E-selectin, fasting glucose, and insulin were estimated in plasma of the patients and compared with controls. Restrictive type of ventilatory change was observed in DM patients. Diffusing capacity (% predicted) in the supine position (P < 0.0001), postural change in DLco (P < 0.0001), and coefficient of diffusion were significantly less in DM patients as compared to controls. Plasma levels of VCAM-1 were significantly higher in DM patients without microangiopathy and negatively correlated (r = -0.4054, P = 0.0094) with Δ DLco in all diabetic subjects. All patients had significantly higher insulin resistance. Lack of postural increase in diffusing capacity in type 2 diabetic patients along with increased VCAM-1 levels could reflect the presence of an early microangiopathy of the small pulmonary vessels.

Reduction in membrane component of diffusing capacity is associated with the extent of acute pulmonary embolism

PubMed Central

Piirilä, Päivi; Laiho, Mia; Mustonen, Pirjo; Graner, Marit; Piilonen, Anneli; Raade, Merja; Sarna, Seppo; Harjola, Veli-Pekka; Sovijärvi, Anssi

2011-01-01

Acute pulmonary embolism (PE) often decreases pulmonary diffusing capacity for carbon monoxide (DL,CO), but data on the mechanisms involved are inconsistent. We wanted to investigate whether reduction in diffusing capacity of alveolo-capillary membrane (DM) and pulmonary capillary blood volume (Vc) is associated with the extent of PE or the presence and severity of right ventricular dysfunction (RVD) induced by PE and how the possible changes are corrected after 7-month follow-up. Forty-seven patients with acute non-massive PE in spiral computed tomography (CT) were included. The extent of PE was assessed by scoring mass of embolism. DL,CO, Vc, DM and alveolar volume (VA) were measured by using a single breath method with carbon monoxide and oxygen both at the acute phase and 7 months later. RVD was evaluated with transthoracic echocardiography and electrocardiogram. Fifteen healthy subjects were included as controls. DL,CO, DL, CO/VA, DM, vital capacity (VC) and VA were significantly lower in the patients with acute PE than in healthy controls (P<0·001). DM/Vc relation was significantly lower in patients with RVD than in healthy controls (P = 0·004). DM correlated inversely with central mass of embolism (r = −0·312; P = 0·047) whereas Vc did not. DM, DL,CO, VC and VA improved significantly within 7 months. In all patients (P = 0·001, P = 0·001) and persistent RVD (P = 0·020, P = 0·012), DM and DL,CO remained significantly lower than in healthy controls in the follow-up. DM was inversely related to central mass of embolism. Reduction in DM mainly explains the sustained decrease in DL,CO in PE after 7 months despite modern treatment of PE. PMID:21143754

Measurement of CO2 diffusivity for carbon sequestration: a microfluidic approach for reservoir-specific analysis.

PubMed

Sell, Andrew; Fadaei, Hossein; Kim, Myeongsub; Sinton, David

2013-01-02

Predicting carbon dioxide (CO(2)) security and capacity in sequestration requires knowledge of CO(2) diffusion into reservoir fluids. In this paper we demonstrate a microfluidic based approach to measuring the mutual diffusion coefficient of carbon dioxide in water and brine. The approach enables formation of fresh CO(2)-liquid interfaces; the resulting diffusion is quantified by imaging fluorescence quenching of a pH-dependent dye, and subsequent analyses. This method was applied to study the effects of site-specific variables--CO(2) pressure and salinity levels--on the diffusion coefficient. In contrast to established, macro-scale pressure-volume-temperature cell methods that require large sample volumes and testing periods of hours/days, this approach requires only microliters of sample, provides results within minutes, and isolates diffusive mass transport from convective effects. The measured diffusion coefficient of CO(2) in water was constant (1.86 [± 0.26] × 10(-9) m(2)/s) over the range of pressures (5-50 bar) tested at 26 °C, in agreement with existing models. The effects of salinity were measured with solutions of 0-5 M NaCl, where the diffusion coefficient varied up to 3 times. These experimental data support existing theory and demonstrate the applicability of this method for reservoir-specific testing.

Simultaneous measurement of pulmonary diffusing capacity for carbon monoxide and nitric oxide.

PubMed

Yamaguchi, Kazuhiro; Tsuji, Takao; Aoshiba, Kazutetsu; Nakamura, Hiroyuki

2018-03-01

In Europe and America, the newly-developed, simultaneous measurement of diffusing capacity for CO (D LCO ) and NO (D LNO ) has replaced the classic D LCO measurement for detecting the pathophysiological abnormalities in the acinar regions. However, simultaneous measurement of D LCO and D LNO is currently not used by Japanese physicians. To encourage the use of D LNO in Japan, the authors reviewed aspects of simultaneously-estimated D LCO and D LNO from previously published manuscripts. The simultaneous D LCO -D LNO technique identifies the alveolocapillary membrane-related diffusing capacity (membrane component, D M ) and the blood volume in pulmonary microcirculation (V C ); V C is the principal factor constituting the blood component of diffusing capacity (D B ,D B =θ·V C where θ is the specific gas conductance for CO or NO in the blood). As the association velocity of NO with hemoglobin (Hb) is fast and the affinity of NO with Hb is high in comparison with those of CO, θ NO can be taken as an invariable simply determined by diffusion limitation inside the erythrocyte. This means that θ NO is independent of the partial pressure of oxygen (PO 2 ). However, θ CO involves the limitations by diffusion and chemical reaction elicited by the erythrocyte, resulting in θ CO to be a PO 2 -dependent variable. Furthermore, D LCO is determined primarily by D B (∼77%), while D LNO is determined equally by D M (∼55%) and D B (∼45%). This suggests that D LCO is more sensitive for detecting microvascular diseases, while D LNO can equally identify alveolocapillary membrane and microcirculatory abnormalities. Copyright © 2017 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.

Airway diffusing capacity of nitric oxide and steroid therapy in asthma.

PubMed

Shin, Hye-Won; Rose-Gottron, Christine M; Cooper, Dan M; Newcomb, Robert L; George, Steven C

2004-01-01

Exhaled nitric oxide (NO) concentration is a noninvasive index for monitoring lung inflammation in diseases such as asthma. The plateau concentration at constant flow is highly dependent on the exhalation flow rate and the use of corticosteroids and cannot distinguish airway and alveolar sources. In subjects with steroid-naive asthma (n = 8) or steroid-treated asthma (n = 12) and in healthy controls (n = 24), we measured flow-independent NO exchange parameters that partition exhaled NO into airway and alveolar regions and correlated these with symptoms and lung function. The mean (+/-SD) maximum airway flux (pl/s) and airway tissue concentration [parts/billion (ppb)] of NO were lower in steroid-treated asthmatic subjects compared with steroid-naive asthmatic subjects (1,195 +/- 836 pl/s and 143 +/- 66 ppb compared with 2,693 +/- 1,687 pl/s and 438 +/- 312 ppb, respectively). In contrast, the airway diffusing capacity for NO (pl.s-1.ppb-1) was elevated in both asthmatic groups compared with healthy controls, independent of steroid therapy (11.8 +/- 11.7, 8.71 +/- 5.74, and 3.13 +/- 1.57 pl.s-1.ppb-1 for steroid treated, steroid naive, and healthy controls, respectively). In addition, the airway diffusing capacity was inversely correlated with both forced expired volume in 1 s and forced vital capacity (%predicted), whereas the airway tissue concentration was positively correlated with forced vital capacity. Consistent with previously reported results from Silkoff et al. (Silkoff PE, Sylvester JT, Zamel N, and Permutt S, Am J Respir Crit Med 161: 1218-1228, 2000) that used an alternate technique, we conclude that the airway diffusing capacity for NO is elevated in asthma independent of steroid therapy and may reflect clinically relevant changes in airways.

Pulmonary 3He Magnetic Resonance Imaging Biomarkers of Regional Airspace Enlargement in Alpha-1 Antitrypsin Deficiency.

PubMed

Lessard, Eric; Young, Heather M; Bhalla, Anurag; Pike, Damien; Sheikh, Khadija; McCormack, David G; Ouriadov, Alexei; Parraga, Grace

2017-11-01

Thoracic x-ray computed tomography (CT) and hyperpolarized 3 He magnetic resonance imaging (MRI) provide quantitative measurements of airspace enlargement in patients with emphysema. For patients with panlobular emphysema due to alpha-1 antitrypsin deficiency (AATD), sensitive biomarkers of disease progression and response to therapy have been difficult to develop and exploit, especially those biomarkers that correlate with outcomes like quality of life. Here, our objective was to generate and compare CT and diffusion-weighted inhaled-gas MRI measurements of emphysema including apparent diffusion coefficient (ADC) and MRI-derived mean linear intercept (L m ) in patients with AATD, chronic obstructive pulmonary disease (COPD) ex-smokers, and elderly never-smokers. We enrolled patients with AATD (n = 8; 57 ± 7 years), ex-smokers with COPD (n = 8; 77 ± 6 years), and a control group of never-smokers (n = 5; 64 ± 2 years) who underwent thoracic CT, MRI, spirometry, plethysmography, the St. George's Respiratory Questionnaire, and the 6-minute walk test during a single 2-hour visit. MRI-derived ADC, L m , surface-to-volume ratio, and ventilation defect percent were generated for the apical, basal, and whole lung as was CT lung area ≤-950 Hounsfield units (RA 950 ), low attenuating clusters, and airway count. In patients with AATD, there was a significantly different MRI-derived ADC (P = .03), L m (P < .0001), and surface-to-volume ratio (P < .0001), but not diffusing capacity of carbon monoxide, residual volume or total lung capacity, or CT RA 950 (P > .05) compared to COPD ex-smokers with a significantly different St. George's Respiratory Questionnaire. In this proof-of-concept demonstration, we evaluated CT and MRI lung emphysema measurements and observed significantly worse MRI biomarkers of emphysema in patients with AATD compared to patients with COPD, although CT RA 950 and diffusing capacity of carbon monoxide were not significantly different, underscoring the sensitivity of MRI measurements of AATD emphysema. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

The measurement of lung volumes using body plethysmography and helium dilution methods in COPD patients: a correlation and diagnosis analysis.

PubMed

Tang, Yongjiang; Zhang, Mingke; Feng, Yulin; Liang, Binmiao

2016-11-23

Chronic obstructive pulmonary disease (COPD) is a chronic airway disease characterized by persistent airflow limitation. Moreover, lung hyperinflation evaluated by lung volumes is also the key pathophysiologic process during COPD progression. Nevertheless, there is still no preferred method to evaluate lung volumes. For this study, we recruited 170 patients with stable COPD to assess lung volumes stratified by airflow limitation severity. Lung volumes including residual volume (RV) and total lung capacity (TLC) were determined by both body plethysmography and helium dilution methods. The discrepancies between these two methods were recorded as ΔRV%pred, ΔTLC%pred, and ΔRV/TLC. We found that ΔRV%pred, ΔTLC%pred, and ΔRV/TLC increased significantly with the severity of COPD. The differences of lung capacity between these two methods were negatively correlated with FEV 1 %pred, and diffusing capacity for carbon monoxide (D L CO%pred). Moreover, the receiver operating characteristic (ROC) for ΔTLC%pred to distinguish severe COPD from non-severe COPD had an area under curve (AUC) of 0.886. The differences of lung volume parameters measured by body plethysmography and helium dilution methods were associated with airflow limitation and can effectively differentiate COPD severity, which may be a supportive method to assess the lung function of stable COPD patients.

Lung function, transfusion, pulmonary capillary blood volume and sickle cell disease.

PubMed

Lunt, Alan; McGhee, Emily; Robinson, Polly; Rees, David; Height, Susan; Greenough, Anne

2016-02-01

Lung function abnormalities occur in children with sickle cell disease (SCD) and may be associated with elevated pulmonary blood volume. To investigate that association, we determined whether blood transfusion in SCD children acutely increased pulmonary capillary blood volume (PCBV) and increased respiratory system resistance (Rrs5). Measurements of Rrs5 and spirometry were made before and after blood transfusion in 18 children, median age 14.2 (6.6-18.5) years. Diffusing capacity for carbon monoxide and nitric oxide were assessed to calculate the PCBV. Post transfusion, the median Rrs5 had increased from 127.4 to 141.3% predicted (p<0.0001) and pulmonary capillary blood volume from 39.7 to 64.1 ml/m2 (p<0.0001); forced expiratory volume in one second (p=0.0056) and vital capacity (p=0.0008) decreased. The increase in Rrs5 correlated with the increase in PCBV (r=0.50, p=0.0493). Increased pulmonary capillary blood volume may at least partially explain the lung function abnormalities in SCD children. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of side lying on lung function in older individuals.

PubMed

Manning, F; Dean, E; Ross, J; Abboud, R T

1999-05-01

Body positioning exerts a strong effect on pulmonary function, but its effect on other components of the oxygen transport pathway are less well understood, especially the effects of side-lying positions. This study investigated the interrelationships between side-lying positions and indexes of lung function such as spirometry, alveolar diffusing capacity, and inhomogeneity of ventilation in older individuals. Nineteen nonsmoking subjects (mean age=62.8 years, SD=6.8, range=50-74) with no history of cardiac or pulmonary disease were tested over 2 sessions. The test positions were sitting and left side lying in one session and sitting and right side lying in the other session. In each of the positions, forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), single-breath pulmonary diffusing capacity (DLCO/VA), and the slope of phase III (DN2%/L) of the single-breath nitrogen washout test to determine inhomogeneity of ventilation were measured. Compared with measurements obtained in the sitting position, FVC and FEV1 were decreased equally in the side-lying positions, but no change was observed in DLCO/VA or DN2%/L. Side-lying positions resulted in decreases in FVC and FEV1, which is consistent with the well-documented effects of the supine position. These findings further support the need for prescriptive rather than routine body positioning of patients with risks of cardiopulmonary compromise and the need to use upright positions in which lung volumes and capacities are maximized.

Improved diffusivity of NaOH solution in autohydrolyzed poplar sapwood chips for chemi-mechanical pulp production.

PubMed

Zhang, Honglei; Hou, Qingxi; Liu, Wei; Yue, Zhen; Jiang, Xiaoya; Ma, Xixi

2018-07-01

This work investigated the changes in the physical structure of autohydrolyzed poplar sapwood chips and the effect on the subsequent alkali liquor diffusion properties for chemi-mechanical pulping (CMP). An alkali impregnation process was conducted by using the autohydrolyzed poplar sapwood with different levels of autohydrolysis intensity. The results showed that the volume porosity, water constraint capacity, and saturated water absorption of the autohydrolyzed poplar sapwood chips increased. Also, the effective capillary cross-sectional area (ECCSA) in the radial direction and the diffusion coefficients of NaOH solution in both the radial and axial directions all increased. Autohydrolysis pretreatment enhanced the alkali liquor diffusion properties in poplar sapwood chips, and the diffusion coefficient was increased more greatly in the radial direction than that in the axial direction. Copyright © 2018 Elsevier Ltd. All rights reserved.

A MoO2 sheet as a promising electrode material: ultrafast Li-diffusion and astonishing Li-storage capacity

NASA Astrophysics Data System (ADS)

Zhou, Yungang; Geng, Cheng

2017-03-01

The potential of MoO2 crystal as an electrode material is reported, and nanostructural MoO2 systems, including nanoparticles, nanospheres, nanobelts and nanowires, were synthesized and proved to be advanced electrode materials. A two-dimensional (2D) geometric structure represents an extreme of surface-to-volume ratio, and thus is more suitable as an electrode material in general. Stimulated by the recent fabrication of 2D MoO2, we adopted an ab initio molecular dynamics simulation and density functional theory calculation to study the stability and electrochemical properties of a MoO2 sheet. Identified by a phonon dispersion curve and potential energy curve calculations, the MoO2 sheet proved to be dynamically and thermally stable. After lithiation, similar to most promising 2D structures, we found that a Li atom can strongly adsorb on a MoO2 sheet, and the lithiated MoO2 sheet presented excellent metallic properties. Note that, compared with most promising 2D structures, we unexpectedly revealed that the diffusion barrier of the Li atom on the MoO2 sheet was much lower and the storage capacity of the MoO2 sheet was much larger. The calculated energy barrier for the diffusion of Li on the MoO2 sheet was only 75 meV, and, due to multilayer adsorption, the theoretical capacity of the MoO2 sheet can reach up to 2513 mA h g-1. Benefiting from general properties, such as strong Li-binding and excellent conductivity, and unique phenomena, such as ultrafast diffusion capacity and astonishing storage capacity, we highlight a new promising electrode material for the Li-ion battery.

Diffusion capacity and CT measures of emphysema and airway wall thickness - relation to arterial oxygen tension in COPD patients.

PubMed

Saure, Eirunn Waatevik; Bakke, Per Sigvald; Lind Eagan, Tomas Mikal; Aanerud, Marianne; Jensen, Robert Leroy; Grydeland, Thomas Blix; Johannessen, Ane; Nilsen, Roy Miodini; Thorsen, Einar; Hardie, Jon Andrew

2016-01-01

Decreased diffusing capacity of the lung for carbon monoxide (DLCO) is associated with emphysema. DLCO is also related to decreased arterial oxygen tension (PaO2), but there are limited data on associations between PaO2 and computed tomography (CT) derived measures of emphysema and airway wall thickness. To examine whether CT measures of emphysema and airway wall thickness are associated with level of arterial oxygen tension beyond that provided by measurements of diffusion capacity and spirometry. The study sample consisted of 271 smoking or ex-smoking COPD patients from the Bergen COPD Cohort Study examined in 2007-2008. Emphysema was assessed as percent of low-attenuation areas<-950 Hounsfield units (%LAA), and airway wall thickness as standardised measure at an internal perimeter of 10 mm (AWT-Pi10). Multiple linear regression models were fitted with PaO2 as the outcome variable, and %LAA, AWT-Pi10, DLCO and carbon monoxide transfer coefficient (KCO) as main explanatory variables. The models were adjusted for sex, age, smoking status, and haemoglobin concentration, as well as forced expiratory volume in one second (FEV1). Sixty two per cent of the subjects were men, mean (SD) age was 64 (7) years, mean (SD) FEV1 in percent predicted was 50 (15)%, and mean PaO2 (SD) was 9.3 (1.1) kPa. The adjusted regression coefficient (CI) for PaO2 was -0.32 (-0.04-(-0.019)) per 10% increase in %LAA (p<0.01). When diffusion capacity and FEV1 were added to the model, respectively, the association lost its statistical significance. No relationship between airway wall thickness and PaO2 was found. CT assessment of airway wall thickness is not associated with arterial oxygen tension in COPD patients. Emphysema score measured by chest CT, is related to decreased PaO2, but cannot replace measurements of diffusion capacity in the clinical evaluation of hypoxaemia.

Why Are High Altitude Natives So Strong at High Altitude? Nature vs. Nurture: Genetic Factors vs. Growth and Development.

PubMed

Brutsaert, Tom

Among high-altitude natives there is evidence of a general hypoxia tolerance leading to enhanced performance and/or increased capacity in several important domains. These domains likely include an enhanced physical work capacity, an enhanced reproductive capacity, and an ability to resist several common pathologies of chronic high-altitude exposure. The "strength" of the high-altitude native in this regard may have both a developmental and a genetic basis, although there is better evidence for the former (developmental effects) than for the latter. For example, early-life hypoxia exposure clearly results in lung growth and remodeling leading to an increased O2 diffusing capacity in adulthood. Genetic research has yet to reveal a population genetic basis for enhanced capacity in high-altitude natives, but several traits are clearly under genetic control in Andean and Tibetan populations e.g., resting and exercise arterial O2 saturation (SaO2). This chapter reviews the effects of nature and nurture on traits that are relevant to the process of gas exchange, including pulmonary volumes and diffusion capacity, the maximal oxygen consumption (VO2max), the SaO2, and the alveolar-arterial oxygen partial pressure difference (A-aDO2) during exercise.

Unravelling the impact of reaction paths on mechanical degradation of intercalation cathodes for lithium-ion batteries

DOE PAGES

Li, Juchuan; Zhang, Qinglin; Xiao, Xingcheng; ...

2015-10-18

The intercalation compounds are generally considered as ideal electrode materials for lithium-ion batteries thanks to their minimum volume expansion and fast lithium ion diffusion. However, cracking still occurs in those compounds and has been identified as one of the critical issues responsible for their capacity decay and short cycle life, although the diffusion-induced stress and volume expansion are much smaller than those in alloying-type electrodes. Here, we designed a thin-film model system that enables us to tailor the cation ordering in LiNi 0.5Mn 1.5O 4 spinels and correlate the stress patterns, phase evolution, and cycle performances. Surprisingly, we found thatmore » distinct reaction paths cause negligible difference in the overall stress patterns but significantly different cracking behaviors and cycling performances: 95% capacity retention for disordered LiNi 0.5Mn 1.5O 4 and 48% capacity retention for ordered LiNi 0.5Mn 1.5O 4 after 2000 cycles. We were able to pinpoint that the extended solid-solution region with suppressed phase transformation attributed to the superior electrochemical performance of disordered spinel. Furthermore, this work envisions a strategy for rationally designing stable cathodes for lithium-ion batteries through engineering the atomic structure that extends the solid-solution region and suppresses phase transformation.« less

Reduction in membrane component of diffusing capacity is associated with the extent of acute pulmonary embolism.

PubMed

Piirilä, Päivi; Laiho, Mia; Mustonen, Pirjo; Graner, Marit; Piilonen, Anneli; Raade, Merja; Sarna, Seppo; Harjola, Veli-Pekka; Sovijärvi, Anssi

2011-05-01

Acute pulmonary embolism (PE) often decreases pulmonary diffusing capacity for carbon monoxide (DL,CO), but data on the mechanisms involved are inconsistent. We wanted to investigate whether reduction in diffusing capacity of alveolo-capillary membrane (DM) and pulmonary capillary blood volume (Vc) is associated with the extent of PE or the presence and severity of right ventricular dysfunction (RVD) induced by PE and how the possible changes are corrected after 7-month follow-up. Forty-seven patients with acute non-massive PE in spiral computed tomography (CT) were included. The extent of PE was assessed by scoring mass of embolism. DL,CO, Vc, DM and alveolar volume (VA) were measured by using a single breath method with carbon monoxide and oxygen both at the acute phase and 7 months later. RVD was evaluated with transthoracic echocardiography and electrocardiogram. Fifteen healthy subjects were included as controls. DL,CO, DL, CO/VA, DM, vital capacity (VC) and VA were significantly lower in the patients with acute PE than in healthy controls (P < 0.001). DM/Vc relation was significantly lower in patients with RVD than in healthy controls (P = 0.004). DM correlated inversely with central mass of embolism (r = -0.312; P = 0.047) whereas Vc did not. DM, DL,CO, VC and VA improved significantly within 7 months. In all patients (P = 0.001, P = 0.001) and persistent RVD (P = 0.020, P = 0.012), DM and DL,CO remained significantly lower than in healthy controls in the follow-up. DM was inversely related to central mass of embolism. Reduction in DM mainly explains the sustained decrease in DL,CO in PE after 7 months despite modern treatment of PE. © 2010 The Authors. Clinical Physiology and Functional Imaging © 2010 Scandinavian Society of Clinical Physiology and Nuclear Medicine.

Nitric oxide airway diffusing capacity and mucosal concentration in asthmatic schoolchildren.

PubMed

Pedroletti, Christophe; Högman, Marieann; Meriläinen, Pekka; Nordvall, Lennart S; Hedlin, Gunilla; Alving, Kjell

2003-10-01

Asthmatic patients show increased concentrations of nitric oxide (NO) in exhaled air (Feno). The diffusing capacity of NO in the airways (Dawno), the NO concentrations in the alveoli and the airway wall, and the maximal airway NO diffusion rate have previously been estimated noninvasively by measuring Feno at different exhalation flow rates in adults. We investigated these variables in 15 asthmatic schoolchildren (8-18 y) and 15 age-matched control subjects, with focus on their relation to exhaled NO at the recommended exhalation flow rate of 0.05 L/s (Feno0.05), age, and volume of the respiratory anatomic dead space. NO was measured on-line by chemiluminescence according to the European Respiratory Society's guidelines, and the NO plateau values at three different exhalation flow rates (11, 99, and 382 mL/s) were incorporated in a two-compartment model for NO diffusion. The NO concentration in the airway wall (p < 0.001), Dawno (p < 0.01), and the maximal airway NO diffusion rate (p < 0.001) were all higher in the asthmatic children than in control children. In contrast, there was no difference in the NO concentration in the alveoli (p = 0.13) between the groups. A positive correlation was seen between the volume of the respiratory anatomic dead space and Feno0.05 (r = 0.68, p < 0.01), the maximal airway NO diffusion rate (r = 0.71, p < 0.01), and Dawno (r = 0.56, p < 0.01) in control children, but not in asthmatic children. Feno0.05 correlated better with Dawno in asthmatic children (r = 0.65, p < 0.01) and with the NO concentration in the airway wall in control subjects (r < 0.77, p < 0.001) than vice versa. We conclude that Feno0.05 increases with increasing volume of the respiratory anatomic dead space in healthy children, suggesting that normal values for Feno0.05 should be related to age or body weight in this age group. Furthermore, the elevated Feno0.05 seen in asthmatic children is related to an increase in both Dawno and NO concentration in the airway wall. Because Dawno correlates with the volume of the respiratory anatomic dead space in control subjects and Feno0.05 correlates with Dawno in asthmatic children, we suggest that Dawno partly reflects the total NO-producing surface area and that a larger part of the bronchial tree produces NO in asthmatic children than in control children.

Interstitial pneumonitis after acetylene welding: a case report.

PubMed

Brvar, Miran

2014-01-01

Acetylene is a colorless gas commonly used for welding. It acts mainly as a simple asphyxiant. In this paper, however, we present a patient who developed a severe interstitial pneumonitis after acetylene exposure during aluminum welding. A 44-year old man was welding with acetylene, argon and aluminum electrode sticks in a non-ventilated aluminum tank for 2 h. Four hours after welding dyspnea appeared and 22 h later he was admitted at the Emergency Department due to severe respiratory insufficiency with pO2 = 6.7 kPa. Chest X-ray showed diffuse interstitial infiltration. Pulmonary function and gas diffusion tests revealed a severe restriction (55% of predictive volume) and impaired diffusion capacity (47% of predicted capacity). Toxic interstitial pneumonitis was diagnosed and high-dose systemic corticosteroid methylprednisolone and inhalatory corticosteroid fluticasone therapy was started. Computed Tomography (CT) of the lungs showed a diffuse patchy ground-glass opacity with no signs of small airway disease associated with interstitial pneumonitis. Corticosteroid therapy was continued for the next 8 weeks gradually reducing the doses. The patient's follow-up did not show any deterioration of respiratory function. In conclusion, acetylene welding might result in severe toxic interstitial pneumonitis that improves after an early systemic and inhalatory corticosteroid therapy.

Single-breath diffusing capacity for carbon monoxide instrument accuracy across 3 health systems.

PubMed

Hegewald, Matthew J; Markewitz, Boaz A; Wilson, Emily L; Gallo, Heather M; Jensen, Robert L

2015-03-01

Measuring diffusing capacity of the lung for carbon monoxide (DLCO) is complex and associated with wide intra- and inter-laboratory variability. Increased D(LCO) variability may have important clinical consequences. The objective of the study was to assess instrument performance across hospital pulmonary function testing laboratories using a D(LCO) simulator that produces precise and repeatable D(LCO) values. D(LCO) instruments were tested with CO gas concentrations representing medium and high range D(LCO) values. The absolute difference between observed and target D(LCO) value was used to determine measurement accuracy; accuracy was defined as an average deviation from the target value of < 2.0 mL/min/mm Hg. Accuracy of inspired volume measurement and gas sensors were also determined. Twenty-three instruments were tested across 3 healthcare systems. The mean absolute deviation from the target value was 1.80 mL/min/mm Hg (range 0.24-4.23) with 10 of 23 instruments (43%) being inaccurate. High volume laboratories performed better than low volume laboratories, although the difference was not significant. There was no significant difference among the instruments by manufacturers. Inspired volume was not accurate in 48% of devices; mean absolute deviation from target value was 3.7%. Instrument gas analyzers performed adequately in all instruments. D(LCO) instrument accuracy was unacceptable in 43% of devices. Instrument inaccuracy can be primarily attributed to errors in inspired volume measurement and not gas analyzer performance. D(LCO) instrument performance may be improved by regular testing with a simulator. Caution should be used when comparing D(LCO) results reported from different laboratories. Copyright © 2015 by Daedalus Enterprises.

Pulmonary function in space

NASA Technical Reports Server (NTRS)

West, J. B.; Elliott, A. R.; Guy, H. J.; Prisk, G. K.

1997-01-01

The lung is exquisitely sensitive to gravity, and so it is of interest to know how its function is altered in the weightlessness of space. Studies on National Aeronautics and Space Administration (NASA) Spacelabs during the last 4 years have provided the first comprehensive data on the extensive changes in pulmonary function that occur in sustained microgravity. Measurements of pulmonary function were made on astronauts during space shuttle flights lasting 9 and 14 days and were compared with extensive ground-based measurements before and after the flights. Compared with preflight measurements, cardiac output increased by 18% during space flight, and stroke volume increased by 46%. Paradoxically, the increase in stroke volume occurred in the face of reductions in central venous pressure and circulating blood volume. Diffusing capacity increased by 28%, and the increase in the diffusing capacity of the alveolar membrane was unexpectedly large based on findings in normal gravity. The change in the alveolar membrane may reflect the effects of uniform filling of the pulmonary capillary bed. Distributions of blood flow and ventilation throughout the lung were more uniform in space, but some unevenness remained, indicating the importance of nongravitational factors. A surprising finding was that airway closing volume was approximately the same in microgravity and in normal gravity, emphasizing the importance of mechanical properties of the airways in determining whether they close. Residual volume was unexpectedly reduced by 18% in microgravity, possibly because of uniform alveolar expansion. The findings indicate that pulmonary function is greatly altered in microgravity, but none of the changes observed so far will apparently limit long-term space flight. In addition, the data help to clarify how gravity affects pulmonary function in the normal gravity environment on Earth.

Changes in lung volumes and gas trapping in patients with large hiatal hernia.

PubMed

Naoum, Christopher; Kritharides, Leonard; Ing, Alvin; Falk, Gregory L; Yiannikas, John

2017-03-01

Studies assessing hiatal hernia (HH)-related effects on lung volumes derived by body plethysmography are limited. We aimed to evaluate the effect of hernia size on lung volumes (including assessment by body plethysmography) and the relationship to functional capacity, as well as the impact of corrective surgery. Seventy-three patients (70 ± 10 years; 54 female) with large HH [mean ± standard deviation, intra-thoracic stomach (ITS) (%): 63 ± 20%; type III in 65/73] had respiratory function data (spirometry, 73/73; body plethysmography, 64/73; diffusing capacity, 71/73) and underwent HH surgery. Respiratory function was analysed in relation to hernia size (groups I, II and III: ≤50, 50%-75% and ≥75% ITS, respectively) and functional capacity. Post-operative changes were quantified in a subgroup. Total lung capacity (TLC) and vital capacity (VC) correlated inversely with hernia size (TLC: 97 ± 11%, 96 ± 13%, 88 ± 10% predicted in groups I, II and III, respectively, P = 0.01; VC: 110 ± 17%, 111 ± 14%, 98 ± 14% predicted, P = 0.02); however, mean values were normal and only 14% had abnormal lung volumes. Surgery increased TLC (93 ± 11% vs 97 ± 10% predicted) and VC (105 ± 15% vs 116 ± 18%), and decreased residual volume/total lung capacity (RV/TLC) ratio (39 ± 7% vs 37 ± 6%) (P < 0.01 for all). Respiratory changes were modest relative to the marked functional class improvement. Among parameters that improved following HH surgery, decreased TLC and forced expiratory volume in 1 s and increased RV/TLC ratio correlated with poorer functional class pre-operatively. Increasing HH size correlates with reduced TLC and VC. Surgery improves lung volumes and gas trapping; however, the changes are mild and within the normal range. © 2015 John Wiley & Sons Ltd.

Computed Tomographic Measures of Pulmonary Vascular Morphology in Smokers and Their Clinical Implications

PubMed Central

Estépar, Raúl San José; Kinney, Gregory L.; Black-Shinn, Jennifer L.; Bowler, Russell P.; Kindlmann, Gordon L.; Ross, James C.; Kikinis, Ron; Han, MeiLan K.; Come, Carolyn E.; Diaz, Alejandro A.; Cho, Michael H.; Hersh, Craig P.; Schroeder, Joyce D.; Reilly, John J.; Lynch, David A.; Crapo, James D.; Wells, J. Michael; Dransfield, Mark T.; Hokanson, John E.

2013-01-01

Rationale: Angiographic investigation suggests that pulmonary vascular remodeling in smokers is characterized by distal pruning of the blood vessels. Objectives: Using volumetric computed tomography scans of the chest we sought to quantitatively evaluate this process and assess its clinical associations. Methods: Pulmonary vessels were automatically identified, segmented, and measured. Total blood vessel volume (TBV) and the aggregate vessel volume for vessels less than 5 mm2 (BV5) were calculated for all lobes. The lobe-specific BV5 measures were normalized to the TBV of that lobe and the nonvascular tissue volume (BV5/TissueV) to calculate lobe-specific BV5/TBV and BV5/TissueV ratios. Densitometric measures of emphysema were obtained using a Hounsfield unit threshold of −950 (%LAA-950). Measures of chronic obstructive pulmonary disease severity included single breath measures of diffusing capacity of carbon monoxide, oxygen saturation, the 6-minute-walk distance, St George’s Respiratory Questionnaire total score (SGRQ), and the body mass index, airflow obstruction, dyspnea, and exercise capacity (BODE) index. Measurements and Main Results: The %LAA-950 was inversely related to all calculated vascular ratios. In multivariate models including age, sex, and %LAA-950, lobe-specific measurements of BV5/TBV were directly related to resting oxygen saturation and inversely associated with both the SGRQ and BODE scores. In similar multivariate adjustment lobe-specific BV5/TissueV ratios were inversely related to resting oxygen saturation, diffusing capacity of carbon monoxide, 6-minute-walk distance, and directly related to the SGRQ and BODE. Conclusions: Smoking-related chronic obstructive pulmonary disease is characterized by distal pruning of the small blood vessels (<5 mm2) and loss of tissue in excess of the vasculature. The magnitude of these changes predicts the clinical severity of disease. PMID:23656466

Characterization of biochars derived from agriculture wastes and their adsorptive removal of atrazine from aqueous solution: A comparative study.

PubMed

Liu, Na; Charrua, Alberto Bento; Weng, Chih-Huang; Yuan, Xiaoling; Ding, Feng

2015-12-01

The physicochemical properties of biochars produced from soybeans (SBB), corn stalks (CSB), rice stalks (RSB), poultry manure (PMB), cattle manure (CMB), and pig manure (PgMB) and their adsorption characteristics of atrazine were investigated. The adsorption capacity increased with the increase of temperature and initial atrazine concentration. More atrazine was removed from basic solutions than acidic solutions, due to the effects of adsorption and hydrolysis. The Freundlich isotherm adsorption parameters indicated that the adsorption capacity decreased in the order SBB>RSB>CMB>CSB>PMB>PgMB, which is associated to the pore volume of biochars. The total pore volume and biochar pH were concluded to play important roles in determining the adsorption capacity, and they may have contributed to physical adsorption mechanisms dominating the overall adsorption process (the low activation energy for all of the biochars). Modified Freundlich and intraparticle diffusion models were used to describe the kinetics of the adsorption process. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Benefits of Exercise Training on Aerobic Capacity in Patients with Heart Failure and Preserved Ejection Fraction.

PubMed

do Prado, Danilo Marcelo Leite; Rocco, Enéas Antônio

2017-01-01

Heart failure with preserved ejection fraction (HFpEF) is defined as an inability of the ventricles to optimally accept blood from atria with blunted end- diastolic volume response by limiting the stroke volume and cardiac output. The HEpEF prevalence is higher in elderly and women and may be associated to hypertension, diabetes mellitus and atrial fibrillation. Severe exercise intolerance, manifested by dyspnea and fatigue during physical effort is the important chronic symptom in HFpEF patients, in which is the major determinant of their reduced quality of life. In this sense, several studies demonstrated reduced aerobic capacity in terms of lower peak oxygen consumption (peak VO 2 ) in patients with HFpEF. In addition, the lower aerobic capacity observed in HFpEF may be due to impaired both convective and diffusive O 2 transport (i.e. reduced cardiac output and arteriovenous oxygen difference, respectively).Exercise training program can help restore physiological function in order to increase aerobic capacity and improve the quality of life in HFpEF patients. Therefore, the primary purpose of this chapter was to clarify the physiological mechanisms associated with reduced aerobic capacity in HFpEF patients. Secondly, special focus was devoted to show how aerobic exercise training can improve aerobic capacity and quality of life in HFpEF patients.

Nonuniformity of diffusing capacity from small alveolar gas samples is increased in smokers.

PubMed

Cotton, D J; Mink, J T; Graham, B L

1998-01-01

Although centrilobular emphysema, and small airway, interstitial and alveoli inflammation can be detected pathologically in the lungs of smokers with relatively well preserved lung function, these changes are difficult to assess using available physiological tests. Because submaximal single breath washout (SBWSM) manoeuvres improve the detection of abnormalities in ventilation inhomogeneity in the lung periphery in smokers compared with traditional vital capacity manoeuvres, SBWSM manoeuvres were used in this study to measure temporal differences in diffusing capacity using a rapid response carbon monoxide analyzer. To determine whether abnormalities in the lung periphery can be detected in smokers with normal forced expired volumes in 1 s using the three-equation diffusing capacity (DLcoSB-3EQ) among small alveolar gas samples and whether the abnormalities correlate with increases in peripheral ventilation inhomogeneity. Cross-sectional study in 21 smokers and 21 nonsmokers all with normal forced exhaled flow rates. Both smokers and nonsmokers performed SBWSM manoeuvres consisting of slow inhalation of test gas from functional residual capacity to one-half inspiratory capacity with either 0 or 10 s of breath holding and slow exhalation to residual volume (RV). They also performed conventional vital capacity single breath (SBWVC) manoeuvres consisting of slow inhalation of test gas from RV to total lung capacity and, without breath holding, slow exhalation to RV. DLcoSB-3EQ was calculated from the total alveolar gas sample. DLcoSB-3EQ was also calculated from four equal sequential, simulated aliquots of the total alveolar gas sample. DLcoSB-3EQ values from the four alveolar samples were normalized by expressing each as a percentge of DLcoSB-3EQ from the entire alveolar gas sample. An index of variation (DI) among the small-sample DLcoSB-3EQ values was correlated with the normalized phase III helium slope (Sn) and the mixing efficiency (Emix). For SBWSM, DI was increased in smokers at 0 s of breath holding compared with nonsmokers, and correlated with age, smoking pack-years and Sn. The decrease in DI with breath holding was greater in smokers and correlated with the change in Sn with breath holding. For SBWVC manoeuvres, there were no differences due to smoking in Sn or Emix, but DI was increased in smokers and correlated with age and smoking pack-years, but not with Sn. For SBWSM manoeuvres the increase in DI in smokers correlated with breath hold time-dependent increases in Sn, suggesting that the changes in DI reflected the same structural alterations that caused increases in peripheral ventilation inhomogeneity. For SBWVC manoeuvres, the increase in DI in smokers was not associated with changes in ventilation inhomogeneity, suggesting that the effect of smoking on DI during this manoeuvre was due to smoke-related changes in alveolar capillary diffusion, rather than due solely to alterations in the distribution of ventilation.

Breakdown of lung framework and an increase in pores of Kohn as initial events of emphysema and a cause of reduction in diffusing capacity.

PubMed

Yoshikawa, Akira; Sato, Shuntaro; Tanaka, Tomonori; Hashisako, Mikiko; Kashima, Yukio; Tsuchiya, Tomoshi; Yamasaki, Naoya; Nagayasu, Takeshi; Yamamoto, Hiroshi; Fukuoka, Junya

2016-01-01

Pulmonary emphysema is the pathological prototype of chronic obstructive pulmonary disease and is also associated with other lung diseases. We considered that observation with different approaches may provide new insights for the pathogenesis of emphysema. We reviewed tissue blocks of the lungs of 25 cases with/without emphysema and applied a three-dimensional observation method to the blocks. Based on the three-dimensional characteristics of the alveolar structure, we considered one face of the alveolar polyhedron as a structural unit of alveoli and called it a framework unit (FU). We categorized FUs based on their morphological characteristics and counted their number to evaluate the destructive changes in alveoli. We also evaluated the number and the area of pores of Kohn in FUs. We performed linear regression analysis to estimate the effect of these data on pulmonary function tests. In multivariable regression analysis, a decrease in the number of FUs without an alveolar wall led to a significant decrease in the diffusing capacity of the lung for carbon monoxide (DLCO) and DLCO per unit alveolar volume, and an increase in the area of pores of Kohn had a significant effect on an increase in residual capacity. A breakdown in the lung framework and an increase in pores of Kohn are associated with a decrease in DLCO and DLCO per unit alveolar volume with/without emphysema.

CCL21 and IP-10 as blood biomarkers for pulmonary involvement in systemic lupus erythematosus patients.

PubMed

Odler, B; Bikov, A; Streizig, J; Balogh, C; Kiss, E; Vincze, K; Barta, I; Horváth, I; Müller, V

2017-05-01

Biomarkers for pulmonary manifestations in systemic lupus erythematosus (SLE) are missing. Plasma samples of nine SLE patients with known pulmonary involvement (SLE pulm ) and nine SLE patients without pulmonary involvement (SLE) were tested by multiplex microarray analysis for various cyto- and chemokines. Significantly decreased lung function paramters for forced vital capacity (FVC), total lung capacity (TLC), diffusion capacity for carbon monoxide (DL CO ) and diffusion of CO corrected on lung volume (KL CO ) were observed in SLE pulm as compared to SLE patients. CC chemokine ligand 21 (CCL21) and interferon gamma-induced protein 10 (IP-10) levels were significantly higher in SLE pulm , than in patients without pulmonary manifestations. CCL21 correlated negatively with DL CO ( r = -0.73; p < 0.01) and KL CO ( r = -0.62; p < 0.01), while IP-10 with FVC and forced expiratory volume one second. Receiver Operating Characteristics (ROC) analysis confirmed high sensitivity and specificity for the separation of SLE patients with and without pulmonary involvement for the chemokines CCL21 (Area Under Curve (AUC): 0.85; sensitivity%: 88.90; specificity%: 75.00; p < 0.01) and IP-10 (AUC: 0.82; sensitivity%: 66.67, specificity%: 100; p < 0.01). Pleuropulmonary manifestations in SLE patients associated with lung functional and DL CO /KL CO changes and were associated with significant increase in CCL21 and IP-10. These chemokines might serve as potential biomarkers of lung involvement in SLE patients.

Improved Ionic Diffusion through the Mesoporous Carbon Skin on Silicon Nanoparticles Embedded in Carbon for Ultrafast Lithium Storage.

PubMed

An, Geon-Hyoung; Kim, Hyeonjin; Ahn, Hyo-Jin

2018-02-21

Because of their combined effects of outstanding mechanical stability, high electrical conductivity, and high theoretical capacity, silicon (Si) nanoparticles embedded in carbon are a promising candidate as electrode material for practical utilization in Li-ion batteries (LIBs) to replace the conventional graphite. However, because of the poor ionic diffusion of electrode materials, the low-grade ultrafast cycling performance at high current densities remains a considerable challenge. In the present study, seeking to improve the ionic diffusion, we propose a novel design of mesoporous carbon skin on the Si nanoparticles embedded in carbon by hydrothermal reaction, poly(methyl methacrylate) coating process, and carbonization. The resultant electrode offers a high specific discharge capacity with excellent cycling stability (1140 mA h g -1 at 100 mA g -1 after 100 cycles), superb high-rate performance (969 mA h g -1 at 2000 mA g -1 ), and outstanding ultrafast cycling stability (532 mA h g -1 at 2000 mA g -1 after 500 cycles). The battery performances are surpassing the previously reported results for carbon and Si composite-based electrodes on LIBs. Therefore, this novel approach provides multiple benefits in terms of the effective accommodation of large volume expansions of the Si nanoparticles, a shorter Li-ion diffusion pathway, and stable electrochemical conditions from a faster ionic diffusion during cycling.

Low level CO2 effects on pulmonary function in humans

NASA Technical Reports Server (NTRS)

Sexton, J.; Mueller, K.; Elliott, A.; Gerzer, D.; Strohl, K. P.; West, J. B. (Principal Investigator)

1998-01-01

The purpose of the study was to determine whether chamber exposure to low levels of CO2 results in functional alterations in gas mixing and closing volume in humans. Four healthy volunteer subjects were exposed to 0.7% CO2 and to 1.2% CO2. Spirometry, lung volumes, single breath nitrogen washout, diffusing capacity for carbon monoxide (DLCO) by two methods, and cardiac output were measured in triplicate. Values were obtained over two non-consecutive days during the training period (control) and on days 2 or 3, 4, 6, 10, 13, and 23 of exposure to each CO2 level. Measurements were made during the same time of day. There was one day of testing after exposure, while still in the chamber but off carbon dioxide. The order of testing, up until measurements of DLCO and cardiac output, were randomized to avoid presentation effects. The consistent findings were a reduction in diffusing capacity for carbon monoxide and a fall in cardiac output, occurring to a similar degree with both exposures. For the group as a whole, there was no indication of major effects on spirometry, lung volumes, gas mixing or dead space. We conclude that small changes may occur in the function of distal gas exchanging units; however, these effects were not associated with any adverse health effects. The likelihood of pathophysiologic changes in lung function or structure with 0.7 or 1.2% CO2 exposure for this period of time, is therefore, low.

Effects of body position on the carbon monoxide diffusing capacity in patients with chronic heart failure: relation to hemodynamic changes.

PubMed

Faggiano, P; D'Aloia, A; Simoni, P; Gualeni, A; Foglio, K; Ambrosino, N; Giordano, A

1998-01-01

Pulmonary diffusion has been found to be reduced in patients with congestive heart failure. The effects of postural changes on the diffusing capacity had been evaluated in healthy subjects, but not in patients with heart failure. The aim of this study was to evaluate the posture-induced changes in diffusing capacity in patients with chronic heart failure and their relation to the hemodynamic profile. The pulmonary carbon monoxide diffusing capacity (DLCO) was measured in the supine position, with 20 degrees passive head elevation, and in the sitting position, both postures maintained for 10 min, in a group of 32 male patients with mild to moderate chronic heart failure due to left ventricular systolic dysfunction (ejection fraction <35%). On a separate day, in the absence of any changes in clinical status and therapy, the hemodynamic parameters were measured by right-heart catheterization. The sequence of postures was assigned randomly. The mean values of DLCO were slightly reduced and did not differ in the two positions (20.3 +/- 5.7 vs. 19.4 +/- 5.6 ml/min/mm Hg, 77 +/- 23 vs. 75 +/- 20% of predicted, respectively). The patients were then subdivided according to changes in DLCO from the supine to the sitting position: DLCO increased (+23%) in 9 patients (28%, group 1), decreased (-17.5%) in 17 patients (53%, group 2), and remained within the coefficient of reproducibility ( +/- 5 %) in 6 patients (group 3). As compared with group 2, group 1 patients showed a significant increase in mean pulmonary artery pressure (+7 vs. -15%, p < 0.01) and pulmonary capillary wedge pressure (+8 vs. -22%, p < 0.005) from the supine to the sitting position, while the cardiac index showed a smaller - but not significant - decrease in group 1 (-5 vs. -12%). The percent changes in DLCO significantly correlated with changes in pulmonary capillary wedge (r = 0.54, p < 0.0005) and mean pulmonary artery (r = 0.47, p < 0.005) pressures. In chronic heart failure postural changes may induce different responses in diffusing capacity. To a greater extent than in healthy subjects, the most common response is a decrease in DLCO in the sitting as compared with the supine position. The DLCO changes correlate with variations in pulmonary circulation pressure, probably due to changes in pulmonary vascular recruitment and pulmonary capillary blood volume.

Stereological estimation of the surface area and oxygen diffusing capacity of the respiratory stomach of the air-breathing armored catfish Pterygoplichthys anisitsi (Teleostei: Loricariidae).

PubMed

da Cruz, André Luis; Pedretti, Ana Carolina Elias; Fernandes, Marisa Narciso

2009-05-01

The stomach of Pterygoplichthys anisitsi has a thin, translucent wall and a simple squamous epithelium with an underlying dense capillary network. In the cardiac and pyloric regions, most cells have short microvilli distributed throughout the cell surface and their edges are characterized by short, densely packed microvilli. The mucosal layer of the stomach has two types of pavement epithelial cells that are similar to those in the aerial respiratory organs. Type 1 pavement epithelial cells, resembling the Type I pneumocyte in mammal lungs, are flat, with a large nucleus, and extend a thin sheet of cytoplasm on the underlying capillary. Type 2 cells, resembling the Type II pneumocyte, possess numerous mitochondria, a well-developed Golgi complex, rough endoplasmic reticulum, and numerous lamellar bodies in different stages of maturation. The gastric glands, distributed throughout the mucosal layer, also have several cells with many lamellar bodies. The total volume (air + tissue), tissue, and air capacity of the stomach when inflated, increase along with body mass. The surface-to-tissue-volume ratio of stomach varies from 108 cm(-1) in the smallest fish (0.084 kg) to 59 cm(-1) in the largest fish (0.60 kg). The total stomach surface area shows a low correlation to body mass. Nevertheless, the body-mass-specific surface area varied from 281.40 cm(2) kg(-1) in the smallest fish to 68.08 cm(2) kg(-1) in the largest fish, indicating a negative correlation to body mass (b = -0.76). The arithmetic mean barrier thickness between air and blood was 1.52 +/- 0.07 microm, whereas the harmonic mean thickness (tau(h)) of the diffusion barrier ranged from 0.40 to 0.74 microm. The anatomical diffusion factor (ADF = cm(2) microm(-1) kg(-1)) and the morphological O(2) diffusion capacity (D(morphol)O(2) = cm(3) min(-1) mmHg(-1) kg(-1)) are higher in the smallest specimen and lower in the largest one. In conclusion, the structure and morphometric data of P. anisitsi stomach indicate that this organ is adapted for oxygen uptake from air. (c) 2008 Wiley-Liss, Inc.

Relationship between the baseline alveolar volume-to-total lung capacity ratio and airway responsiveness.

PubMed

Kaminsky, David A; Daud, Anees; Chapman, David G

2014-10-01

Ventilation heterogeneity (VH) has been linked to airway responsiveness (AR) based on various measures of VH involving inert gas washout, forced oscillation and lung imaging. We explore whether VH at baseline, as measured by the simple ratio of single breath alveolar volume to plethysmographically determined total lung capacity (VA/TLC), would correlate with AR as measured by methacholine challenge testing. We analysed data from spirometry, lung volumes, diffusing capacity and methacholine challenge to derive the VA/TLC and the dose-response slope (DRS) of forced expiratory volume in 1 s (DRS-FEV1) during methacholine challenge from 136 patients. We separated out airway closure versus narrowing by examining the DRS for forced vital capacity (DRS-FVC) and the DRS for FEV1/FVC (DRS-FEV1/FVC), respectively. Similarly, we calculated the DRS for sGaw (DRS-sGaw) as another measure of airway narrowing. We performed statistical analysis using Spearman rank correlation and multifactor linear regression using a backward stepwise modelling procedure. We found that the DRS-FEV1 correlated with baseline VA/TLC (rho = -0.26, P < 0.01), and VA/TLC and FEV1 were independently associated with DRS-FEV1 (R(2)  = 0.14, P = 0.01). In addition, VA/TLC was associated with both airway narrowing and closure in response to methacholine. These results confirm that baseline VA/TLC is associated with AR, and reflects both airway closure and airway narrowing following methacholine challenge. © 2014 Asian Pacific Society of Respirology.

[Combined pulmonary fibrosis and emphysema (CPFE)--limitation of usual lung function test and challenge at practice].

PubMed

Takai, Daiya

2014-12-01

Spirometry and the flow-volume curve test are commonly performed lung function tests. However, a unique clinical entity occasionally shows almost normal data in these tests, and is therefore missed on screening tests. The clinical entity of combined pulmonary emphysema and pulmdoary fibrosis was recognized and documented in the 90's in Japan, the USA, and Europe. Typical emphysema shows obstructive disorders, and pulmonary fibrosis shows restrictive disorders. Thus, the combination of both should lead to a combined disorder pattern in lung function tests, but this is not the case. In 2005, Cottin reported and redefined this combination of emphysema and fibrosis of the lung as "Combined Pulmonary Fibrosis and Emphysema" (CPFE). The patients are typically heavily smoking males who show an almost normal lung function. The upper lobe of these patients usually shows severe emphysema, which contributes to a static volume and a late phase in the forced volume test. On the other hand their lower lobe shows fibrotic change. The fibrotic portion contributes to early phase flow in the flow-volume curve. These mechanisms are a reason for the normal pattern appearance in lung function tests in CPFE patients. As a matter of course, these patients have damaged upper and lower lobes: their diffusing capacity of the lung shows a low performance, their saturation of blood hemoglobin decreases soon after light exercise, and their KL-6 (a blood marker of pulmonary fibrosis) usually shows a high value. They are considered a high risk group regarding complications of post-surgical treatment. Thus, when medical technologists identify suspicious cases, they should advise doctors to add diffusing capacity and KL-6 tests. (Review).

Lung diffusing capacity for nitric oxide as a marker of fibrotic changes in idiopathic interstitial pneumonias.

PubMed

Barisione, Giovanni; Brusasco, Claudia; Garlaschi, Alessandro; Baroffio, Michele; Brusasco, Vito

2016-05-01

Lung diffusing capacity for carbon monoxide (DLCO) is decreased in both usual interstitial pneumonia-idiopathic pulmonary fibrosis (UIP-IPF) and nonspecific interstitial pneumonia (NSIP), but is moderately related to computed tomography (CT)-determined fibrotic changes. This may be due to the relative insensitivity of DLCO to changes in alveolar membrane diffusive conductance (DMCO). The purpose of this study was to determine whether measurement of lung diffusing capacity for nitric oxide (DLNO) better reflects fibrotic changes than DLCO DLNO-DLCO were measured simultaneously in 30 patients with UIP-IPF and 30 with NSIP. Eighty-one matched healthy subjects served as a control group. The amount of pulmonary fibrosis was estimated by CT volumetric analysis of visually bounded areas showing reticular opacities and honeycombing. DMCO and pulmonary capillary volume (VC) were calculated. DLNO was below the lower limit of normal in all patients irrespective of extent and nature of disease, whereas DLCO was within the normal range in a nonnegligible number of patients. Both DLNO and DLCO were significantly correlated with visual assessment of fibrosis but DLNO more closely than DLCO DMCO was also below the lower limit of normal in all UIP-IPF and NSIP patients and significantly correlated with fibrosis extent in both diseases, whereas VC was weakly correlated with fibrosis in UIP-IPF and uncorrelated in NSIP, with normal values in half of patients. In conclusion, measurement of DLNO may provide a more sensitive evaluation of fibrotic changes than DLCO in either UIP-IPF or NSIP, because it better reflects DMCO. Copyright © 2016 the American Physiological Society.

Silicon Framework Allotropes for Li-ion and Na-ion Batteries: New Insight for a Reversible Capacity.

NASA Astrophysics Data System (ADS)

Marzouk, Asma; Soto, Fernando; Burgos, Juan; Balbuena, Perla; El-Mellouhi, Fadwa

Silicon has the capacity to host a large amount of Li which makes it an attractive anode material despite suffering from swelling problem leading to irreversible capacity loss. The possibility of an easy extraction of Na atoms from Si24Na4 inspired us to adopt the Si24 as an anode material for Lithium-ion and sodium-ion Batteries. Using DFT, we evaluate the specific capacity and the intercalation potential of Si24 allotrope. Enhanced capacities are sought by designing a new silicon allotrope. We demonstrated that these Si24 allotropes show a negligible volume expansion and conserve their periodic structures after the maximum insertion/disinsertion of the ions which is crucial to prevent the capacity loss during cycling. DFT and ab-initio molecular dynamics (AIMD) studies give insights on the most probable surface adsorption and reaction sites, lithiation and sodiation, as well as initial stages of SEI formation and ionic diffusion. Qatar National Research Fund (QNRF) (NPRP 7-162-2-077).

Pulmonary Vascular Congestion: A Mechanism for Distal Lung Unit Dysfunction in Obesity.

PubMed

Oppenheimer, Beno W; Berger, Kenneth I; Ali, Saleem; Segal, Leopoldo N; Donnino, Robert; Katz, Stuart; Parikh, Manish; Goldring, Roberta M

2016-01-01

Obesity is characterized by increased systemic and pulmonary blood volumes (pulmonary vascular congestion). Concomitant abnormal alveolar membrane diffusion suggests subclinical interstitial edema. In this setting, functional abnormalities should encompass the entire distal lung including the airways. We hypothesize that in obesity: 1) pulmonary vascular congestion will affect the distal lung unit with concordant alveolar membrane and distal airway abnormalities; and 2) the degree of pulmonary congestion and membrane dysfunction will relate to the cardiac response. 54 non-smoking obese subjects underwent spirometry, impulse oscillometry (IOS), diffusion capacity (DLCO) with partition into membrane diffusion (DM) and capillary blood volume (VC), and cardiac MRI (n = 24). Alveolar-capillary membrane efficiency was assessed by calculation of DM/VC. Mean age was 45±12 years; mean BMI was 44.8±7 kg/m2. Vital capacity was 88±13% predicted with reduction in functional residual capacity (58±12% predicted). Despite normal DLCO (98±18% predicted), VC was elevated (135±31% predicted) while DM averaged 94±22% predicted. DM/VC varied from 0.4 to 1.4 with high values reflecting recruitment of alveolar membrane and low values indicating alveolar membrane dysfunction. The most abnormal IOS (R5 and X5) occurred in subjects with lowest DM/VC (r2 = 0.31, p<0.001; r2 = 0.34, p<0.001). Cardiac output and index (cardiac output / body surface area) were directly related to DM/VC (r2 = 0.41, p<0.001; r2 = 0.19, p = 0.03). Subjects with lower DM/VC demonstrated a cardiac output that remained in the normal range despite presence of obesity. Global dysfunction of the distal lung (alveolar membrane and distal airway) is associated with pulmonary vascular congestion and failure to achieve the high output state of obesity. Pulmonary vascular congestion and consequent fluid transudation and/or alterations in the structure of the alveolar capillary membrane may be considered often unrecognized causes of airway dysfunction in obesity.

Three-dimensional cross-linking composite of graphene, carbon nanotubes and Si nanoparticles for lithium ion battery anode

NASA Astrophysics Data System (ADS)

Tian, Suyun; Zhu, Guannan; Tang, Yanping; Xie, Xiaohua; Wang, Qian; Ma, Yufei; Ding, Guqiao; Xie, Xiaoming

2018-03-01

Various graphene-based Si nanocomposites have been reported to improve the performance of active materials in Li-ion batteries. However, these candidates still yield severe capacity fading due to the electrical disconnection and fractures caused by the huge volume changes over extended cycles. Therefore, we have designed a novel three-dimensional cross-linked graphene and single-wall carbon nanotube structure to encapsulate the Si nanoparticles. The synthesized three-dimensional structure is attributed to the excellent self-assembly of carbon nanotubes with graphene oxide as well as a thermal treatment process at 900 °C. This special structure provides sufficient void spaces for the volume expansion of Si nanoparticles and channels for the diffusion of ions and electrons. In addition, the cross-linking of the graphene and single-wall carbon nanotubes also strengthens the stability of the structure. As a result, the volume expansion of the Si nanoparticles is restrained. The specific capacity remains at 1450 mAh g-1 after 100 cycles at 200 mA g-1. This well-defined three-dimensional structure facilitates superior capacity and cycling stability in comparison with bare Si and a mechanically mixed composite electrode of graphene, single-wall carbon nanotubes and silicon nanoparticles.

Fabrication of porous carbon sphere@SnO2@carbon layer coating composite as high performance anode for sodium-ion batteries

NASA Astrophysics Data System (ADS)

Li, Xin; Sun, Xiaohong; Gao, Zhiwen; Hu, Xudong; Guo, Jingdong; Cai, Shu; Guo, Ruisong; Ji, Huiming; Zheng, Chunming; Hu, Wenbin

2018-03-01

SnO2 has triggered lots of research efforts as anode for sodium-ion batteries. However, the volume expansion and poor conductivity lead to an unsatisfactory electrochemical performance for the practical application of SnO2. In this work, a novel carbon-coated SnO2 supported by porous carbon sphere composite is synthesized by hydrothermal process combining with annealing method. The porous carbon sphere@SnO2@carbon layer coating composite anode delivers a reversible capacity of 326 mAh g-1 over 80 cycles at a current density of 50 mA g-1. Even at 1600 mA g-1, a capacity of 82 mAh g-1 is still maintained after 550 cycles. Such excellent performance can be ascribed to the unique structure, which efficiently accommodates volume expansion, enhances conductivity and offers shortened sodium-ion transport pathway. The charge-storage mechanisms can be comprised of diffusion-controlled reaction and pseudocapacitance effect. At high scan rate of 1.0 mV s-1, the capacity contribution of pseudocapacitance effect could reach as high as 78%.

Time‐efficient and flexible design of optimized multishell HARDI diffusion

PubMed Central

Tournier, J. Donald; Price, Anthony N.; Cordero‐Grande, Lucilio; Hughes, Emer J.; Malik, Shaihan; Steinweg, Johannes; Bastiani, Matteo; Sotiropoulos, Stamatios N.; Jbabdi, Saad; Andersson, Jesper; Edwards, A. David; Hajnal, Joseph V.

2017-01-01

Purpose Advanced diffusion magnetic resonance imaging benefits from collecting as much data as is feasible but is highly sensitive to subject motion and the risk of data loss increases with longer acquisition times. Our purpose was to create a maximally time‐efficient and flexible diffusion acquisition capability with built‐in robustness to partially acquired or interrupted scans. Our framework has been developed for the developing Human Connectome Project, but different application domains are equally possible. Methods Complete flexibility in the sampling of diffusion space combined with free choice of phase‐encode‐direction and the temporal ordering of the sampling scheme was developed taking into account motion robustness, internal consistency, and hardware limits. A split‐diffusion‐gradient preparation, multiband acceleration, and a restart capacity were added. Results The framework was used to explore different parameters choices for the desired high angular resolution diffusion imaging diffusion sampling. For the developing Human Connectome Project, a high‐angular resolution, maximally time‐efficient (20 min) multishell protocol with 300 diffusion‐weighted volumes was acquired in >400 neonates. An optimal design of a high‐resolution (1.2 × 1.2 mm2) two‐shell acquisition with 54 diffusion weighted volumes was obtained using a split‐gradient design. Conclusion The presented framework provides flexibility to generate time‐efficient and motion‐robust diffusion magnetic resonance imaging acquisitions taking into account hardware constraints that might otherwise result in sub‐optimal choices. Magn Reson Med 79:1276–1292, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:28557055

Modeling Diffusion Induced Stresses for Lithium-Ion Battery Materials

NASA Astrophysics Data System (ADS)

Chiu Huang, Cheng-Kai

Advancing lithium-ion battery technology is of paramount importance for satisfying the energy storage needs in the U.S., especially for the application in the electric vehicle industry. To provide a better acceleration for electric vehicles, a fast and repeatable discharging rate is required. However, particle fractures and capacity loss have been reported under high current rate (C-rate) during charging/discharging and after a period of cycling. During charging and discharging, lithium ions extract from and intercalate into electrode materials accompanied with the volume change and phase transition between Li-rich phase and Li-poor phase. It is suggested that the diffusion-induced-stress is one of the main reasons causing capacity loss due to the mechanical degradation of electrode particles. Therefore, there is a fundamental need to provide a mechanistic understanding by considering the structure-mechanics-property interactions in lithium-ion battery materials. Among many cathode materials, the olivine-based lithium-iron-phosphate (LiFePO4) with an orthorhombic crystal structure is one of the promising cathode materials for the application in electric vehicles. In this research we first use a multiphysic approach to investigate the stress evolution, especially on the phase boundary during lithiation in single LiFePO4 particles. A diffusion-controlled finite element model accompanied with the experimentally observed phase boundary propagation is developed via a finite element package, ANSYS, in which lithium ion concentration-dependent anisotropic material properties and volume misfits are incorporated. The stress components on the phase boundary are used to explain the Mode I, Mode II, and Mode III fracture propensities in LiFePO4 particles. The elastic strain energy evolution is also discussed to explain why a layer-by-layer lithium insertion mechanism (i.e. first-order phase transformation) is energetically preferred. Another importation issue is how current rate (C-rate) during charging/discharging affects diffusion induced stresses inside electrode materials. For the experimental part we first conduct charging/discharging under different C-rates to observe the voltage responses for commercial LiFePO4 batteries. Then Time-of-Flight Secondary Ion Mass Spectrometry technique is applied to measure the lithium ion intensities in different C-rate charged/discharged samples. These experimental results could be used to support that a more significant voltage fluctuation under high C-rates is due to different lithium insertion mechanisms, rather than the amount of lithium ions intercalated into electrode materials. Thus the investigation of C-rate-dependent stress evolution is required for the development of a more durable lithium ion battery. In this dissertation, we extend the single particle finite element model to investigate the C-rate-dependent diffusion induced stresses in a multi-particle system. Concentration dependent anisotropic material properties, C-rate-dependent volume misfits and concentration dependent Li-ion diffusivity are incorporated in the model. The concentration gradients, diffusion induced stresses, and strain energies under different C-rates are discussed in this study. Particle fractures have been observed in many experimental results, in this study we further discuss the effect of the crack surface orientation on the lithium concentration profile and stress level in cathode materials. The results of this dissertation provide a better understanding of diffusion induced stresses in electrode materials and contribute to our fundamental knowledge of interplay between lithium intercalations, stress evolutions, particle fractures and the capacity fade in lithium-ion batteries.

Developmental and genetic components explain enhanced pulmonary volumes of female Peruvian Quechua.

PubMed

Kiyamu, Melisa; Bigham, Abigail; Parra, Esteban; León-Velarde, Fabiola; Rivera-Chira, María; Brutsaert, Tom D

2012-08-01

High altitude natives have enlarged vital capacities and residual volumes (RV). Because pulmonary volumes are an indication of functionally relevant traits, such as diffusion capacity, the understanding of the factors (genetic/developmental) that influence lung volumes provides insight into the adaptive responses of highlanders. In order to test for the effect of growth and development at high altitude on lung volumes, we obtained forced vital capacities (FVC), RV, and total lung capacities (TLC) for a sample of 65 Peruvian females of mostly Quechua origins (18-34 years) who were sub-divided into two well-matched groups: 1) sea-level born and raised females (BSL, n = 34) from Lima, Peru (150 m), and 2) high-altitude born and raised females (BHA, n = 31) from Cerro de Pasco, Peru (4,338 m). To determine Quechua origins, Native American ancestry proportion (NAAP) for each individual was assessed using a panel of 70 ancestry informative markers. NAAP was similar between groups (BSL = 91.71%; BHA = 89.93%; P = 0.240), and the analysis confirmed predominantly Quechua origins. After adjusting for body size and NAAP, BHA females had significantly higher FVC (3.79 ± 0.06 l; P < 0.001), RV (0.98 ± 0.03 l; P < 0.001) and TLC (4.80 ± 0.07 l; P < 0.001) compared to BSL females (FVC = 3.33 ± 0.05 l; RV = 0.69 ± 0.03 l; TLC = 4.02 ± 0.06 l). NAAP was not associated with FVC (P = 0.352) or TLC (P = 0.506). However, NAAP was positively associated with RV (P = 0.004). In summary, results indicate that developmental exposure to high altitude in females constitutes an important factor for all lung volumes, whereas both genetic and developmental factors seem to be important for RV. Copyright © 2012 Wiley Periodicals, Inc.

Treatment of idiopathic pulmonary fibrosis with losartan: a pilot project.

PubMed

Couluris, Marisa; Kinder, Brent W; Xu, Ping; Gross-King, Margaret; Krischer, Jeffrey; Panos, Ralph J

2012-10-01

Idiopathic pulmonary fibrosis is a progressive interstitial lung disease with no current effective therapies. Treatment has focused on antifibrotic agents to stop proliferation of fibroblasts and collagen deposition in the lung. We present the first clinical trial data on the use of losartan, an antifibrotic agent, to treat idiopathic pulmonary fibrosis. The primary objective was to evaluate the effect of losartan on progression of idiopathic pulmonary fibrosis measured by the change in percentage of predicted forced vital capacity (%FVC) after 12 months. Secondary outcomes included the change in forced expiratory volume at 1 second, diffusing capacity of carbon monoxide, 6-minute walk test distance, and baseline/transition dyspnea index. Patients with idiopathic pulmonary fibrosis and a baseline %FVC of ≥50 % were treated with losartan 50 mg by mouth daily for 12 months. Pulmonary function testing, 6-minute walk, and breathlessness indices were measured every 3 months. Twenty participants with idiopathic pulmonary fibrosis were enrolled and 17 patients were evaluable for response. Twelve patients had a stable or improved %FVC at study month 12. Similar findings were observed in secondary end-point measures, including 58, 71, and 65 % of patients with stable or improved forced expiratory volume at 1 second, diffusing capacity for carbon monoxide, and 6-minute walk test distance, respectively. No treatment-related adverse events that resulted in early study discontinuation were reported. Losartan stabilized lung function in patients with idiopathic pulmonary fibrosis over 12 months. Losartan is a promising agent for the treatment of idiopathic pulmonary fibrosis and has a low toxicity profile.

Pleural plaques and their effect on lung function in Libby vermiculite miners.

PubMed

Clark, Kathleen A; Flynn, J Jay; Goodman, Julie E; Zu, Ke; Karmaus, Wilfried J J; Mohr, Lawrence C

2014-09-01

Multiple studies have investigated the relationship between asbestos-related pleural plaques (PPs) and lung function, with disparate and inconsistent results. Most use chest radiographs to identify PPs and simple spirometry to measure lung function. High-resolution CT (HRCT) scanning improves the accuracy of PP identification. Complete pulmonary function tests (PFTs), including spirometry, lung volumes, and diffusing capacity of the lung for carbon monoxide, provide a more definitive assessment of lung function. The goal of this study was to determine, using HRCT scanning and complete PFTs, the effect of PPs on lung function in Libby vermiculite miners. The results of HRCT scanning and complete PFTs performed between January 2000 and August 2012 were obtained from the medical records of 166 Libby vermiculite miners. Multivariate regression analyses with Tukey multivariate adjustment were used to assess statistical associations between the presence of PPs and lung function. Adjustments were made for age, BMI, smoking history, duration of employment, and years since last occupational asbestos exposure. Nearly 90% of miners (n = 149) had evidence of PPs on HRCT scan. No significant differences in spirometry results, lung volumes, or diffusing capacity of the lung for carbon monoxide were found between miners with PPs alone and miners with normal HRCT scans. Miners with both interstitial fibrosis and the presence of PPs had a significantly decreased total lung capacity in comparison with miners with normal HRCT scans (P = .02). Age, cumulative smoking history, and BMI were significant covariates that contributed to abnormal lung function. Asbestos-related PPs alone have no significant effect on lung function in Libby vermiculite miners.

Understanding the initial irreversibility of metal sulfides for sodium-ion batteries via operando techniques

DOE PAGES

Wang, Liguang; Wang, Jiajun; Guo, Fangmin; ...

2018-11-13

Transition metal sulfides are promising high capacity anodes for sodium-ion batteries in terms of the conversion reaction with multiple alkali metal ions. Nonetheless, some inherent challenges such as sluggish sodium ion diffusion kinetics, large volume change, and poor cycle stability limit their implementation. Addressing these issues necessitates a comprehensive understanding the complex sodium ion storage mechanism particularly at the initial cycle. Here, taking nickel subsulfide as a model material, we reveal the complicated conversion reaction mechanism upon the first cycle by combining in operando 2D transmission X-ray microscopy with X-ray absorption spectroscopy, ex-situ 3D nano-tomography, high-energy X-ray diffraction and electrochemicalmore » impedance spectroscopy. This study demonstrates that the microstructure evolution, inherent slow sodium ions diffusion kinetics, and slow ion mobility at the two-phase interface contribute to the high irreversible capacity upon the first cycle. Finally, such understandings are critical for developing the conversion reaction materials with the desired electrochemical activity and stability.« less

Understanding the initial irreversibility of metal sulfides for sodium-ion batteries via operando techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Liguang; Wang, Jiajun; Guo, Fangmin

Transition metal sulfides are promising high capacity anodes for sodium-ion batteries in terms of the conversion reaction with multiple alkali metal ions. Nonetheless, some inherent challenges such as sluggish sodium ion diffusion kinetics, large volume change, and poor cycle stability limit their implementation. Addressing these issues necessitates a comprehensive understanding the complex sodium ion storage mechanism particularly at the initial cycle. Here, taking nickel subsulfide as a model material, we reveal the complicated conversion reaction mechanism upon the first cycle by combining in operando 2D transmission X-ray microscopy with X-ray absorption spectroscopy, ex-situ 3D nano-tomography, high-energy X-ray diffraction and electrochemicalmore » impedance spectroscopy. This study demonstrates that the microstructure evolution, inherent slow sodium ions diffusion kinetics, and slow ion mobility at the two-phase interface contribute to the high irreversible capacity upon the first cycle. Finally, such understandings are critical for developing the conversion reaction materials with the desired electrochemical activity and stability.« less

Evaluation of computer-based computer tomography stratification against outcome models in connective tissue disease-related interstitial lung disease: a patient outcome study.

PubMed

Jacob, Joseph; Bartholmai, Brian J; Rajagopalan, Srinivasan; Brun, Anne Laure; Egashira, Ryoko; Karwoski, Ronald; Kokosi, Maria; Wells, Athol U; Hansell, David M

2016-11-23

To evaluate computer-based computer tomography (CT) analysis (CALIPER) against visual CT scoring and pulmonary function tests (PFTs) when predicting mortality in patients with connective tissue disease-related interstitial lung disease (CTD-ILD). To identify outcome differences between distinct CTD-ILD groups derived following automated stratification of CALIPER variables. A total of 203 consecutive patients with assorted CTD-ILDs had CT parenchymal patterns evaluated by CALIPER and visual CT scoring: honeycombing, reticular pattern, ground glass opacities, pulmonary vessel volume, emphysema, and traction bronchiectasis. CT scores were evaluated against pulmonary function tests: forced vital capacity, diffusing capacity for carbon monoxide, carbon monoxide transfer coefficient, and composite physiologic index for mortality analysis. Automated stratification of CALIPER-CT variables was evaluated in place of and alongside forced vital capacity and diffusing capacity for carbon monoxide in the ILD gender, age physiology (ILD-GAP) model using receiver operating characteristic curve analysis. Cox regression analyses identified four independent predictors of mortality: patient age (P < 0.0001), smoking history (P = 0.0003), carbon monoxide transfer coefficient (P = 0.003), and pulmonary vessel volume (P < 0.0001). Automated stratification of CALIPER variables identified three morphologically distinct groups which were stronger predictors of mortality than all CT and functional indices. The Stratified-CT model substituted automated stratified groups for functional indices in the ILD-GAP model and maintained model strength (area under curve (AUC) = 0.74, P < 0.0001), ILD-GAP (AUC = 0.72, P < 0.0001). Combining automated stratified groups with the ILD-GAP model (stratified CT-GAP model) strengthened predictions of 1- and 2-year mortality: ILD-GAP (AUC = 0.87 and 0.86, respectively); stratified CT-GAP (AUC = 0.89 and 0.88, respectively). CALIPER-derived pulmonary vessel volume is an independent predictor of mortality across all CTD-ILD patients. Furthermore, automated stratification of CALIPER CT variables represents a novel method of prognostication at least as robust as PFTs in CTD-ILD patients.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reiss, T.F.; Golden, J.

Pneumocystis carinii pneumonia was suggested by a diffuse, bilateral pulmonary uptake of gallium-67 in an asymptomatic, homosexual male with the antibody to the immunodeficiency virus (HIV) who was undergoing staging evaluation for lymphoma clinically localized to a left inguinal lymph node. Chest radiograph and pulmonary function evaluation, including lung volumes, diffusing capacity and arterial blood gases, were within normal limits. Bronchoalveolar lavage revealed Pneumocystis carinii organisms. In this asymptomatic, HIV-positive patient, active alveolar infection, evidenced by abnormal gallium-67 scanning, predated pulmonary physiologic abnormalities. This observation raises questions concerning the natural history of this disease process and the specificity of physiologicmore » tests for excluding disease. It also has implications for the treatment of neoplasia in the HIV-positive patient population.« less

Engineering three-dimensionally electrodeposited Si-on-Ni inverse opal structure for high volumetric capacity Li-ion microbattery anode.

PubMed

Liu, Hao; Cho, Hyung-Man; Meng, Ying Shirley; Li, Quan

2014-06-25

Aiming at improving the volumetric capacity of nanostructured Li-ion battery anode, an electrodeposited Si-on-Ni inverse opal structure has been proposed in the present work. This type of electrode provides three-dimensional bi-continuous pathways for ion/electron transport and high surface area-to-volume ratios, and thus exhibits lower interfacial resistance, but higher effective Li ions diffusion coefficients, when compared to the Si-on-Ni nanocable array electrode of the same active material mass. As a result, improved volumetric capacities and rate capabilities have been demonstrated in the Si-on-Ni inverse opal anode. We also show that optimization of the volumetric capacities and the rate performance of the inverse opal electrode can be realized by manipulating the pore size of the Ni scaffold and the thickness of the Si deposit.

The relationship between alveolar oxygen tension and the single-breath carbon monoxide diffusing capacity.

PubMed

Kanner, R E; Crapo, R O

1986-04-01

The effects of alveolar oxygen tension (PAO2) on the single-breath carbon monoxide diffusing capacity (DLCO) were quantified and a factor was derived to accommodate for differences in PAO2 over commonly encountered altitudes and/or varying concentrations of oxygen in the test gas mixture (FIO2) We performed duplicate measurements of DLCO in 7 normal subjects with 6 different oxygen fractions (0.176, 0.196, 0.211, 0.22, 0.25, and 0.27). The PAO2 for each test was measured as the PO2 in the alveolar gas sample bag. DLCO varied inversely with PAO2 and changed by 0.35% for each mmHg change in PAO2 (r = -0.62, p less than 0.001). At an FIO2 of 0.25, PAO2 varied between subjects and was highly correlated with each subject's residual volume to total lung capacity ratio (r = -0.84, p less than 0.001). We suggest that laboratories can adjust the measured DLCO when PAO2 is not congruent to 120 mmHg by the following formula: DLCO (corrected = DLCO (measured) x [1.0 + 0.0035 (PAO2 - 120)].

Investigation of Thermal Properties of High-Density Polyethylene/Aluminum Nanocomposites by Photothermal Infrared Radiometry

NASA Astrophysics Data System (ADS)

Koca, H. D.; Evgin, T.; Horny, N.; Chirtoc, M.; Turgut, A.; Tavman, I. H.

2017-12-01

In this study, thermal properties of high-density polyethylene (HDPE) filled with nanosized Al particles (80 nm) were investigated. Samples were prepared using melt mixing method up to filler volume fraction of 29 %, followed by compression molding. By using modulated photothermal radiometry (PTR) technique, thermal diffusivity and thermal effusivity were obtained. The effective thermal conductivity of nanocomposites was calculated directly from PTR measurements and from the measurements of density, specific heat capacity (by differential scanning calorimetry) and thermal diffusivity (obtained from PTR signal amplitude and phase). It is concluded that the thermal conductivity of HDPE composites increases with increasing Al fraction and the highest effective thermal conductivity enhancement of 205 % is achieved at a filler volume fraction of 29 %. The obtained results were compared with the theoretical models and experimental data given in the literature. The results demonstrate that Agari and Uno, and Cheng and Vachon models can predict well the thermal conductivity of HDPE/Al nanocomposites in the whole range of Al fractions.

Lung volume reduction surgery for diffuse emphysema.

PubMed

van Agteren, Joseph Em; Carson, Kristin V; Tiong, Leong Ung; Smith, Brian J

2016-10-14

Lung volume reduction surgery (LVRS) performed to treat patients with severe diffuse emphysema was reintroduced in the nineties. Lung volume reduction surgery aims to resect damaged emphysematous lung tissue, thereby increasing elastic properties of the lung. This treatment is hypothesised to improve long-term daily functioning and quality of life, although it may be costly and may be associated with risks of morbidity and mortality. Ten years have passed since the last version of this review was prepared, prompting us to perform an update. The objective of this review was to gather all available evidence from randomised controlled trials comparing the effectiveness of lung volume reduction surgery (LVRS) versus non-surgical standard therapy in improving health outcomes for patients with severe diffuse emphysema. Secondary objectives included determining which subgroup of patients benefit from LVRS and for which patients LVRS is contraindicated, to establish the postoperative complications of LVRS and its morbidity and mortality, to determine which surgical approaches for LVRS are most effective and to calculate the cost-effectiveness of LVRS. We identified RCTs by using the Cochrane Airways Group Chronic Obstructive Pulmonary Disease (COPD) register, in addition to the online clinical trials registers. Searches are current to April 2016. We included RCTs that studied the safety and efficacy of LVRS in participants with diffuse emphysema. We excluded studies that investigated giant or bullous emphysema. Two independent review authors assessed trials for inclusion and extracted data. When possible, we combined data from more than one study in a meta-analysis using RevMan 5 software. We identified two new studies (89 participants) in this updated review. A total of 11 studies (1760 participants) met the entry criteria of the review, one of which accounted for 68% of recruited participants. The quality of evidence ranged from low to moderate owing to an unclear risk of bias across many studies, lack of blinding and low participant numbers for some outcomes. Eight of the studies compared LVRS versus standard medical care, one compared two closure techniques (stapling vs laser ablation), one looked at the effect of buttressing the staple line on the effectiveness of LVRS and one compared traditional 'resectional' LVRS with a non-resectional surgical approach. Participants completed a mandatory course of pulmonary rehabilitation/physical training before the procedure commenced. Short-term mortality was higher for LVRS (odds ratio (OR) 6.16, 95% confidence interval (CI) 3.22 to 11.79; 1489 participants; five studies; moderate-quality evidence) than for control, but long-term mortality favoured LVRS (OR 0.76, 95% CI 0.61 to 0.95; 1280 participants; two studies; moderate-quality evidence). Participants identified post hoc as being at high risk of death from surgery were those with particularly impaired lung function, poor diffusing capacity and/or homogenous emphysema. Participants with upper lobe-predominant emphysema and low baseline exercise capacity showed the most favourable outcomes related to mortality, as investigators reported no significant differences in early mortality between participants treated with LVRS and those in the control group (OR 0.87, 95% CI 0.23 to 3.29; 290 participants; one study), as well as significantly lower mortality at the end of follow-up for LVRS compared with control (OR 0.45, 95% CI 0.26 to 0.78; 290 participants; one study). Trials in this review furthermore provided evidence of low to moderate quality showing that improvements in lung function parameters other than forced expiratory volume in one second (FEV 1 ), quality of life and exercise capacity were more likely with LVRS than with usual follow-up. Adverse events were more common with LVRS than with control, specifically the occurrence of (persistent) air leaks, pulmonary morbidity (e.g. pneumonia) and cardiovascular morbidity. Although LVRS leads to an increase in quality-adjusted life-years (QALYs), the procedure is relatively costly overall. Lung volume reduction surgery, an effective treatment for selected patients with severe emphysema, may lead to better health status and lung function outcomes, specifically for patients who have upper lobe-predominant emphysema with low exercise capacity, but the procedure is associated with risks of early mortality and adverse events.

Correlation of 68Ga Ventilation-Perfusion PET/CT with Pulmonary Function Test Indices for Assessing Lung Function.

PubMed

Le Roux, Pierre-Yves; Siva, Shankar; Steinfort, Daniel P; Callahan, Jason; Eu, Peter; Irving, Lou B; Hicks, Rodney J; Hofman, Michael S

2015-11-01

Pulmonary function tests (PFTs) are routinely used to assess lung function, but they do not provide information about regional pulmonary dysfunction. We aimed to assess correlation of quantitative ventilation-perfusion (V/Q) PET/CT with PFT indices. Thirty patients underwent V/Q PET/CT and PFT. Respiration-gated images were acquired after inhalation of (68)Ga-carbon nanoparticles and administration of (68)Ga-macroaggregated albumin. Functional volumes were calculated by dividing the volume of normal ventilated and perfused (%NVQ), unmatched and matched defects by the total lung volume. These functional volumes were correlated with forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC, and diffusing capacity for carbon monoxide (DLCO). All functional volumes were significantly different in patients with chronic obstructive pulmonary disease (P < 0.05). FEV1/FVC and %NVQ had the highest correlation (r = 0.82). FEV1 was also best correlated with %NVQ (r = 0.64). DLCO was best correlated with the volume of unmatched defects (r = -0.55). Considering %NVQ only, a cutoff value of 90% correctly categorized 28 of 30 patients with or without significant pulmonary function impairment. Our study demonstrates strong correlations between V/Q PET/CT functional volumes and PFT parameters. Because V/Q PET/CT is able to assess regional lung function, these data support the feasibility of its use in radiation therapy and preoperative planning and assessing pulmonary dysfunction in a variety of respiratory diseases. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Respiratory parameters in elite athletes--does sport have an influence?

PubMed

Mazic, S; Lazovic, B; Djelic, M; Suzic-Lazic, J; Djordjevic-Saranovic, S; Durmic, T; Soldatovic, I; Zikic, D; Gluvic, Z; Zugic, V

2015-01-01

Unlike large population studies about cardiovascular components and how they adapt to intensive physical activity, there is less research into the causes of enlargement of the respiratory system in athletes (e.g. vital capacity, maximum flow rates and pulmonary diffusion capacity). The purpose of this research was to study and compare pulmonary function in different types of sports and compare them with controls in order to find out which sports improve lung function the most. Pulmonary functional capacities, vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and maximum voluntary ventilation (MVV) of 493 top athletes belonging to 15 different sports disciplines and of 16 sedentary individuals were studied. Pulmonary function test was performed according to ATS/ERS guidelines. Basketball, water polo players and rowers had statistically higher vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1) than the healthy sedentary control individuals. Football and volleyball players had lower VC while FVC was higher in the football group compared to controls. Peak expiratory flow was lower in boxing, kayak, rugby, handball, taekwondo and tennis. The maximum voluntary ventilation (MVV) was significantly higher in water polo players and rowers. Boxers had statistically lower MVV than the controls. Players of other sports did not differ from the control group. The study suggests that specific type of training used in basketball, water polo or rowing could have potential for improving pulmonary function and rehabilitation. Copyright © 2014 Sociedade Portuguesa de Pneumologia. Published by Elsevier España, S.L.U. All rights reserved.

Non-destructive thermal wave method applied to study thermal properties of fast setting time endodontic cement

NASA Astrophysics Data System (ADS)

Picolloto, A. M.; Mariucci, V. V. G.; Szpak, W.; Medina, A. N.; Baesso, M. L.; Astrath, N. G. C.; Astrath, F. B. G.; Santos, A. D.; Moraes, J. C. S.; Bento, A. C.

2013-11-01

The thermal wave method is applied for thermal properties measurement in fast endodontic cement (CER). This new formula is developed upon using Portland cement in gel and it was successfully tested in mice with good biocompatibility and stimulated mineralization. Recently, thermal expansion and setting time were measured, conferring to this material twice faster hardening than the well known Angelus Mineral trioxide aggregate (MTA) the feature of fast hardening (˜7 min) and with similar thermal expansion (˜12 μstrain/ °C). Therefore, it is important the knowledge of thermal properties like thermal diffusivity, conductivity, effusivity in order to match thermally the tissue environment upon its application in filling cavities of teeth. Photothermal radiometry technique based on Xe illumination was applied in CER disks 600 μm thick for heating, with prepared in four particle sizes (25, 38, 45, and 53) μm, which were added microemulsion gel with variation volumes (140, 150, 160, and 170) μl. The behavior of the thermal diffusivity CER disks shows linear decay for increase emulsion volume, and in contrast, thermal diffusivity increases with particles sizes. Aiming to compare to MTA, thermal properties of CER were averaged to get the figure of merit for thermal diffusivity as (44.2 ± 3.6) × 10-3 cm2/s, for thermal conductivity (228 ± 32) mW/cm K, the thermal effusivity (1.09 ± 0.06) W s0.5/cm2 K and volume heat capacity (5.2 ± 0.7) J/cm3 K, which are in excellent agreement with results of a disk prepared from commercial MTA-Angelus (grain size < 10 μm using 57 μl of distilled water).

Non-destructive thermal wave method applied to study thermal properties of fast setting time endodontic cement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Picolloto, A. M.; Mariucci, V. V. G.; Szpak, W.

The thermal wave method is applied for thermal properties measurement in fast endodontic cement (CER). This new formula is developed upon using Portland cement in gel and it was successfully tested in mice with good biocompatibility and stimulated mineralization. Recently, thermal expansion and setting time were measured, conferring to this material twice faster hardening than the well known Angelus Mineral trioxide aggregate (MTA) the feature of fast hardening (∼7 min) and with similar thermal expansion (∼12 μstrain/ °C). Therefore, it is important the knowledge of thermal properties like thermal diffusivity, conductivity, effusivity in order to match thermally the tissue environment upon its applicationmore » in filling cavities of teeth. Photothermal radiometry technique based on Xe illumination was applied in CER disks 600 μm thick for heating, with prepared in four particle sizes (25, 38, 45, and 53) μm, which were added microemulsion gel with variation volumes (140, 150, 160, and 170) μl. The behavior of the thermal diffusivity CER disks shows linear decay for increase emulsion volume, and in contrast, thermal diffusivity increases with particles sizes. Aiming to compare to MTA, thermal properties of CER were averaged to get the figure of merit for thermal diffusivity as (44.2 ± 3.6) × 10{sup −3} cm{sup 2}/s, for thermal conductivity (228 ± 32) mW/cm K, the thermal effusivity (1.09 ± 0.06) W s{sup 0.5}/cm{sup 2} K and volume heat capacity (5.2 ± 0.7) J/cm{sup 3} K, which are in excellent agreement with results of a disk prepared from commercial MTA-Angelus (grain size < 10 μm using 57 μl of distilled water)« less

Three-dimensional hollow-structured binary oxide particles as an advanced anode material for high-rate and long cycle life lithium-ion batteries

DOE PAGES

Wang, Deli; Wang, Jie; He, Huan; ...

2015-12-30

Transition metal oxides are among the most promising anode candidates for next-generation lithium-ion batteries for their high theoretical capacity. However, the large volume expansion and low lithium ion diffusivity leading to a poor charging/discharging performance. In this study, we developed a surfactant and template-free strategy for the synthesis of a composite of Co xFe 3–xO 4 hollow spheres supported by carbon nanotubes via an impregnation–reduction–oxidation process. The synergy of the composite, as well as the hollow structures in the electrode materials, not only facilitate Li ion and electron transport, but also accommodate large volume expansion. Using state-of-the-art electron tomography, wemore » directly visualize the particles in 3-D, where the voids in the hollow structures serve to buffer the volume expansion of the material. These improvements result in a high reversible capacity as well as an outstanding rate performance for lithium-ion battery applications. As a result, this study sheds light on large-scale production of hollow structured metal oxides for commercial applications in energy storage and conversion.« less

Effect of yoga practices on pulmonary function tests including transfer factor of lung for carbon monoxide (TLCO) in asthma patients.

PubMed

Singh, Savita; Soni, Ritu; Singh, K P; Tandon, O P

2012-01-01

Prana is the energy, when the self-energizing force embraces the body with extension and expansion and control, it is pranayama. It may affect the milieu at the bronchioles and the alveoli particularly at the alveolo-capillary membrane to facilitate diffusion and transport of gases. It may also increase oxygenation at tissue level. Aim of our study is to compare pulmonary functions and diffusion capacity in patients of bronchial asthma before and after yogic intervention of 2 months. Sixty stable asthmatic-patients were randomized into two groups i.e group 1 (Yoga training group) and group 2 (control group). Each group included thirty patients. Lung functions were recorded on all patients at baseline, and then after two months. Group 1 subjects showed a statistically significant improvement (P<0.001) in Transfer factor of the lung for carbon monoxide (TLCO), forced vital capacity (FVC), forced expiratory volume in 1st sec (FEV1), peak expiratory flow rate (PEFR), maximum voluntary ventilation (MVV) and slow vital capacity (SVC) after yoga practice. Quality of life also increased significantly. It was concluded that pranayama & yoga breathing and stretching postures are used to increase respiratory stamina, relax the chest muscles, expand the lungs, raise energy levels, and calm the body.

Thermal conductivity of supercooled water.

PubMed

Biddle, John W; Holten, Vincent; Sengers, Jan V; Anisimov, Mikhail A

2013-04-01

The heat capacity of supercooled water, measured down to -37°C, shows an anomalous increase as temperature decreases. The thermal diffusivity, i.e., the ratio of the thermal conductivity and the heat capacity per unit volume, shows a decrease. These anomalies may be associated with a hypothesized liquid-liquid critical point in supercooled water below the line of homogeneous nucleation. However, while the thermal conductivity is known to diverge at the vapor-liquid critical point due to critical density fluctuations, the thermal conductivity of supercooled water, calculated as the product of thermal diffusivity and heat capacity, does not show any sign of such an anomaly. We have used mode-coupling theory to investigate the possible effect of critical fluctuations on the thermal conductivity of supercooled water and found that indeed any critical thermal-conductivity enhancement would be too small to be measurable at experimentally accessible temperatures. Moreover, the behavior of thermal conductivity can be explained by the observed anomalies of the thermodynamic properties. In particular, we show that thermal conductivity should go through a minimum when temperature is decreased, as Kumar and Stanley observed in the TIP5P model of water. We discuss physical reasons for the striking difference between the behavior of thermal conductivity in water near the vapor-liquid and liquid-liquid critical points.

Thoracoscopic laser pneumoplasty in the treatment of diffuse bullous emphysema.

PubMed

Wakabayashi, A

1995-10-01

Thoracoscopic laser pneumoplasty in the treatment of diffuse bullous emphysema by means of a contact neodymium:yttrium-aluminum garnet laser was evaluated by a retrospective analysis of the first consecutive 500 procedures in 443 patients. The indication for thoracoscopic laser pneumoplasty was intractable dyspnea. Advanced age (mean age, 67 years), high oxygen dependency (70%), steroid use (46%), and markedly diminished physical capacity (2% bedridden and 27% wheelchair-bound) were noted. Thoracoscopic laser pneumoplasty was carried out under general anesthesia and one-lung ventilation. Type 3 bullae (381 procedures) were contracted by contact neodymium:yttrium-aluminum garnet laser and type 4 bullae (199 procedures) excised. The operative mortality rate was 4.8%. Subjective improvement was reported by 87% of the patients. Follow-up functional evaluation was available in 229 patients, which showed highly significant improvement. A comparison of preoperative and postoperative functional tests between type 3 and 4 bullae patients showed no significant difference, except the latter had higher decrease in airway resistance, residual volume, and total lung capacity. Thoracoscopic laser pneumoplasty is an effective treatment for both type 3 and 4 bullous emphysema with an acceptable risk.

Connection between encounter volume and diffusivity in geophysical flows

NASA Astrophysics Data System (ADS)

Rypina, Irina I.; Smith, Stefan G. Llewellyn; Pratt, Larry J.

2018-04-01

Trajectory encounter volume - the volume of fluid that passes close to a reference fluid parcel over some time interval - has been recently introduced as a measure of mixing potential of a flow. Diffusivity is the most commonly used characteristic of turbulent diffusion. We derive the analytical relationship between the encounter volume and diffusivity under the assumption of an isotropic random walk, i.e., diffusive motion, in one and two dimensions. We apply the derived formulas to produce maps of encounter volume and the corresponding diffusivity in the Gulf Stream region of the North Atlantic based on satellite altimetry, and discuss the mixing properties of Gulf Stream rings. Advantages offered by the derived formula for estimating diffusivity from oceanographic data are discussed, as well as applications to other disciplines.

Disturbances of Pulmonary Function in Mitral Valve Disease

PubMed Central

Palmer, Wilfred H.; Gee, J. B. L.; Mills, F. C.; Bates, D. V.

1963-01-01

To study the sequence of changes in respiratory function that occur in the natural history of mitral stenosis, and the physiological basis of “cardiac dyspnea”, 30 patients with chronic mitral valve disease were subjected to detailed pulmonary function tests. There was no significant change in vital capacity and functional residual capacity. The reduction in maximal mid-expiratory flow rate showed excellent correlation with the respiratory symptoms. The pulmonary capillary blood volume was increased in moderately advanced cases but was consistently reduced in the severest cases. Hyperventilation was due to an increased respiratory rate. Dyspnea was associated with increased respiratory work owing to the interrelation between the reduction in diffusion capacity, compliance, cardiac output, the increase in airway resistance, and the uneven ventilation and perfusion of the lungs. The amount of “effort” required to breathe is incommensurate with the external load in these patients. PMID:14060164

Calculation of thermal conductivity, thermal diffusivity and specific heat capacity of sedimentary rocks using petrophysical well logs

NASA Astrophysics Data System (ADS)

Fuchs, Sven; Balling, Niels; Förster, Andrea

2015-12-01

In this study, equations are developed that predict for synthetic sedimentary rocks (clastics, carbonates and evapourates) thermal properties comprising thermal conductivity, specific heat capacity and thermal diffusivity. The rock groups are composed of mineral assemblages with variable contents of 15 major rock-forming minerals and porosities of 0-30 per cent. Petrophysical properties and their well-logging-tool-characteristic readings were assigned to these rock-forming minerals and to pore-filling fluids. Relationships are explored between each thermal property and other petrophysical properties (density, sonic interval transit time, hydrogen index, volume fraction of shale and photoelectric absorption index) using multivariate statistics. The application of these relations allows computing continuous borehole profiles for each rock thermal property. The uncertainties in the prediction of each property vary depending on the selected well-log combination. Best prediction is in the range of 2-8 per cent for the specific heat capacity, of 5-10 per cent for the thermal conductivity, and of 8-15 for the thermal diffusivity, respectively. Well-log derived thermal conductivity is validated by laboratory data measured on cores from deep boreholes of the Danish Basin, the North German Basin, and the Molasse Basin. Additional validation of thermal conductivity was performed by comparing predicted and measured temperature logs. The maximum deviation between these logs is <3 °C. The thermal-conductivity calculation allowed an evaluation of the depth range in which the palaeoclimatic effect on the subsurface temperature field can be observed in the North German Basin. This effect reduces the surface heat-flow density by 25 mW m-2.

Pulmonary changes in liver transplant candidates with hepatitis C cirrhosis.

PubMed

Al-Moamary, M S; Gorka, T; Al-Traif, I H; Al-Jahdali, H H; Al-Shimemeri, A A; Al-Kanway, B; Abdulkareeem, A A; Abdulkareeem, A A

2001-12-01

Several studies have shown that pulmonary abnormalities are common in patients with end-stage liver disease. However, most of these studies were conducted on patients with heterogeneous etiologies. Therefore, we studied these changes in a homogenous group of hepatitis C cirrhotic patients who were potential candidates for liver transplantation. The charts of 81 patients from King Fahad National Guard Hospital, Riyadh, Kingdom of Saudi Arabia with hepatitis C cirrhosis who were evaluated for liver transplantation were reviewed. The following data was retrieved: echocardiography with micro-bubble study, arterial blood gases, and pulmonary function tests of 81 candidates and reviewed over 3 years from 1994 to 1997. The mean age was 53 (+/-9) years with male to female ratio of 1.4:1. Echocardiographic micro-bubble study, revealed 4 of 62 (7%) had an intrapulmonary shunt. Arterial blood gases results were pH of 7.44 (+/-0.4), partial arterial tension of carbon dioxide of 33 mm Hg (+/-4), partial arterial tension of oxygen of 84 mm Hg (+/-12), and alveolar-arterial gradient of 30 mm Hg (+/-10). Eleven percent had obstructive airway disease, 17% had restrictive lung impairment, and 43% had reduced diffusion capacity. Seventy five percent of patients with reduced diffusion capacity had normal lung volumes. Various pulmonary function test abnormalities did not lead to significant differences in arterial blood gases. Pulmonary changes were frequent in liver transplant candidates with hepatitis C virus cirrhosis with reduced diffusion capacity being the most. Apart from the effect of hepatopulmonary syndrome on arterial oxygenation, other pulmonary abnormalities were not significantly different.

Red Phosphorus Nanodots on Reduced Graphene Oxide as a Flexible and Ultra-Fast Anode for Sodium-Ion Batteries.

PubMed

Liu, Yihang; Zhang, Anyi; Shen, Chenfei; Liu, Qingzhou; Cao, Xuan; Ma, Yuqiang; Chen, Liang; Lau, Christian; Chen, Tian-Chi; Wei, Fei; Zhou, Chongwu

2017-06-27

Sodium-ion batteries offer an attractive option for potential low cost and large scale energy storage due to the earth abundance of sodium. Red phosphorus is considered as a high capacity anode for sodium-ion batteries with a theoretical capacity of 2596 mAh/g. However, similar to silicon in lithium-ion batteries, several limitations, such as large volume expansion upon sodiation/desodiation and low electronic conductance, have severely limited the performance of red phosphorus anodes. In order to address the above challenges, we have developed a method to deposit red phosphorus nanodots densely and uniformly onto reduced graphene oxide sheets (P@RGO) to minimize the sodium ion diffusion length and the sodiation/desodiation stresses, and the RGO network also serves as electron pathway and creates free space to accommodate the volume variation of phosphorus particles. The resulted P@RGO flexible anode achieved 1165.4, 510.6, and 135.3 mAh/g specific charge capacity at 159.4, 31878.9, and 47818.3 mA/g charge/discharge current density in rate capability test, and a 914 mAh/g capacity after 300 deep cycles in cycling stability test at 1593.9 mA/g current density, which marks a significant performance improvement for red phosphorus anodes for sodium-ion chemistry and flexible power sources for wearable electronics.

[Aging of the respiratory system: anatomical changes and physiological consequences].

PubMed

Ketata, W; Rekik, W K; Ayadi, H; Kammoun, S

2012-10-01

The respiratory system undergoes progressive involution with age, resulting in anatomical and functional changes that are exerted on all levels. The rib cage stiffens and respiratory muscles weaken. Distal bronchioles have reduced diameter and tend to be collapsed. Mobilized lung volumes decrease with age while residual volume increases. Gas exchanges are modified with a linear decrease of PaO(2) up to the age of 70 years and a decreased diffusing capacity of carbon monoxide. Ventilatory responses to hypercapnia, hypoxia and exercise decrease in the elderly. Knowledge of changes in the respiratory system related to advancing age is a medical issue of great importance in order to distinguish the effects of aging from those of diseases. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

The effect of aging and cardiorespiratory fitness on the lung diffusing capacity response to exercise in healthy humans.

PubMed

Coffman, Kirsten E; Carlson, Alex R; Miller, Andrew D; Johnson, Bruce D; Taylor, Bryan J

2017-06-01

Aging is associated with deterioration in the structure and function of the pulmonary circulation. We characterized the lung diffusing capacity for carbon monoxide (DL CO ), alveolar-capillary membrane conductance (Dm CO ), and pulmonary-capillary blood volume (Vc) response to discontinuous incremental exercise at 25, 50, 75, and 90% of peak work (W peak ) in four groups: 1 ) Young [27 ± 3 yr, maximal oxygen consumption (V̇o 2max ): 110 ± 18% age predicted]; 2) Young Highly Fit (27 ± 3 yr, V̇o 2max : 147 ± 8% age predicted); 3 ) Old (69 ± 5 yr, V̇o 2max : 116 ± 13% age predicted); and 4 ) Old Highly Fit (65 ± 5 yr, V̇o 2max : 162 ± 18% age predicted). At rest and at 90% W peak , DL CO , Dm CO , and Vc were decreased with age. At 90% W peak , DL CO , Dm CO , and Vc were greater in Old Highly Fit vs. Old adults. The slope of the DL CO -cardiac output (Q̇) relationship from rest to end exercise at 90% W peak was not different between Young, Young Highly Fit, Old, and Old Highly Fit (1.35 vs. 1.44 vs. 1.10 vs. 1.35 ml CO ·mmHg -1 ·liter blood -1 , P = 0.388), with no evidence of a plateau in this relationship during exercise; this was also true for Dm CO -Q̇ and Vc-Q̇. V̇o 2max was positively correlated with 1 ) DL CO , Dm CO , and Vc at rest; and 2 ) the rest to end exercise change in DL CO , Dm CO , and Vc. In conclusion, these data suggest that despite the age-associated deterioration in the structure and function of the pulmonary circulation, expansion of the pulmonary capillary network does not become limited during exercise in healthy individuals regardless of age or cardiorespiratory fitness level. NEW & NOTEWORTHY Healthy aging is a crucial area of research. This article details how differences in age and cardiorespiratory fitness level affect lung diffusing capacity, particularly during high-intensity exercise. We conclude that highly fit older adults do not experience a limit in lung diffusing capacity during high-intensity exercise. Interestingly, however, we found that highly fit older individuals demonstrate greater values of lung diffusing capacity during high-intensity exercise than their less fit age-matched counterparts. Copyright © 2017 the American Physiological Society.

Shrinking lung syndrome as a manifestation of pleuritis: a new model based on pulmonary physiological studies.

PubMed

Henderson, Lauren A; Loring, Stephen H; Gill, Ritu R; Liao, Katherine P; Ishizawar, Rumey; Kim, Susan; Perlmutter-Goldenson, Robin; Rothman, Deborah; Son, Mary Beth F; Stoll, Matthew L; Zemel, Lawrence S; Sandborg, Christy; Dellaripa, Paul F; Nigrovic, Peter A

2013-03-01

The pathophysiology of shrinking lung syndrome (SLS) is poorly understood. We sought to define the structural basis for this condition through the study of pulmonary mechanics in affected patients. Since 2007, most patients evaluated for SLS at our institutions have undergone standardized respiratory testing including esophageal manometry. We analyzed these studies to define the physiological abnormalities driving respiratory restriction. Chest computed tomography data were post-processed to quantify lung volume and parenchymal density. Six cases met criteria for SLS. All presented with dyspnea as well as pleurisy and/or transient pleural effusions. Chest imaging results were free of parenchymal disease and corrected diffusing capacities were normal. Total lung capacities were 39%-50% of predicted. Maximal inspiratory pressures were impaired at high lung volumes, but not low lung volumes, in 5 patients. Lung compliance was strikingly reduced in all patients, accompanied by increased parenchymal density. Patients with SLS exhibited symptomatic and/or radiographic pleuritis associated with 2 characteristic physiological abnormalities: (1) impaired respiratory force at high but not low lung volumes; and (2) markedly decreased pulmonary compliance in the absence of identifiable interstitial lung disease. These findings suggest a model in which pleural inflammation chronically impairs deep inspiration, for example through neural reflexes, leading to parenchymal reorganization that impairs lung compliance, a known complication of persistently low lung volumes. Together these processes could account for the association of SLS with pleuritis as well as the gradual symptomatic and functional progression that is a hallmark of this syndrome.

Encapsulating Silica/Antimony into Porous Electrospun Carbon Nanofibers with Robust Structure Stability for High-Efficiency Lithium Storage.

PubMed

Wang, Hongkang; Yang, Xuming; Wu, Qizhen; Zhang, Qiaobao; Chen, Huixin; Jing, Hongmei; Wang, Jinkai; Mi, Shao-Bo; Rogach, Andrey L; Niu, Chunming

2018-04-24

To address the volume-change-induced pulverization problems of electrode materials, we propose a "silica reinforcement" concept, following which silica-reinforced carbon nanofibers with encapsulated Sb nanoparticles (denoted as SiO 2 /Sb@CNFs) are fabricated via an electrospinning method. In this composite structure, insulating silica fillers not only reinforce the overall structure but also contribute to additional lithium storage capacity; encapsulation of Sb nanoparticles into the carbon-silica matrices efficiently buffers the volume changes during Li-Sb alloying-dealloying processes upon cycling and alleviates the mechanical stress; the porous carbon nanofiber framework allows for fast charge transfer and electrolyte diffusion. These advantageous characteristics synergistically contribute to the superior lithium storage performance of SiO 2 /Sb@CNF electrodes, which demonstrate excellent cycling stability and rate capability, delivering reversible discharge capacities of 700 mA h/g at 200 mA/g, 572 mA h/g at 500 mA/g, and 468 mA h/g at 1000 mA/g each after 400 cycles. Ex situ as well as in situ TEM measurements confirm that the structural integrity of silica-reinforced Sb@CNF electrodes can efficiently withstand the mechanical stress induced by the volume changes. Notably, the SiO 2 /Sb@CNF//LiCoO 2 full cell delivers high reversible capacities of ∼400 mA h/g after 800 cycles at 500 mA/g and ∼336 mA h/g after 500 cycles at 1000 mA/g.

New approaches in the indirect quantification of thermal rock properties in sedimentary basins: the well-log perspective

NASA Astrophysics Data System (ADS)

Fuchs, Sven; Balling, Niels; Förster, Andrea

2016-04-01

Numerical temperature models generated for geodynamic studies as well as for geothermal energy solutions heavily depend on rock thermal properties. Best practice for the determination of those parameters is the measurement of rock samples in the laboratory. Given the necessity to enlarge databases of subsurface rock parameters beyond drill core measurements an approach for the indirect determination of these parameters is developed, for rocks as well a for geological formations. We present new and universally applicable prediction equations for thermal conductivity, thermal diffusivity and specific heat capacity in sedimentary rocks derived from data provided by standard geophysical well logs. The approach is based on a data set of synthetic sedimentary rocks (clastic rocks, carbonates and evaporates) composed of mineral assemblages with variable contents of 15 major rock-forming minerals and porosities varying between 0 and 30%. Petrophysical properties are assigned to both the rock-forming minerals and the pore-filling fluids. Using multivariate statistics, relationships then were explored between each thermal property and well-logged petrophysical parameters (density, sonic interval transit time, hydrogen index, volume fraction of shale and photoelectric absorption index) on a regression sub set of data (70% of data) (Fuchs et al., 2015). Prediction quality was quantified on the remaining test sub set (30% of data). The combination of three to five well-log parameters results in predictions on the order of <15% for thermal conductivity and thermal diffusivity, and of <10% for specific heat capacity. Comparison of predicted and benchmark laboratory thermal conductivity from deep boreholes of the Norwegian-Danish Basin, the North German Basin, and the Molasse Basin results in 3 to 5% larger uncertainties with regard to the test data set. With regard to temperature models, the use of calculated TC borehole profiles approximate measured temperature logs with an error of <3°C along a 4 km deep profile. A benchmark comparison for thermal diffusivity and specific heat capacity is pending. Fuchs, Sven; Balling, Niels; Förster, Andrea (2015): Calculation of thermal conductivity, thermal diffusivity and specific heat capacity of sedimentary rocks using petrophysical well logs, Geophysical Journal International 203, 1977-2000, doi: 10.1093/gji/ggv403

Outlet diffusers to increase culvert capacity.

DOT National Transportation Integrated Search

2016-06-01

Aging infrastructure and changing weather patterns present the need to increase the capacity of existing highway culverts. This research approaches this challenge through the use of diffuser outlet systems to increase pipe capacity and reduce outlet ...

Understanding and improving lithium ion batteries through mathematical modeling and experiments

NASA Astrophysics Data System (ADS)

Deshpande, Rutooj D.

There is an intense, worldwide effort to develop durable lithium ion batteries with high energy and power densities for a wide range of applications, including electric and hybrid electric vehicles. For improvement of battery technology understanding the capacity fading mechanism in batteries is of utmost importance. Novel electrode material and improved electrode designs are needed for high energy- high power batteries with less capacity fading. Furthermore, for applications such as automotive applications, precise cycle-life prediction of batteries is necessary. One of the critical challenges in advancing lithium ion battery technologies is fracture and decrepitation of the electrodes as a result of lithium diffusion during charging and discharging operations. When lithium is inserted in either the positive or negative electrode, there is a volume change associated with insertion or de-insertion. Diffusion-induced stresses (DISs) can therefore cause the nucleation and growth of cracks, leading to mechanical degradation of the batteries. With different mathematical models we studied the behavior of diffusion induces stresses and effects of electrode shape, size, concentration dependent material properties, pre-existing cracks, phase transformations, operating conditions etc. on the diffusion induced stresses. Thus we develop tools to guide the design of the electrode material with better mechanical stability for durable batteries. Along with mechanical degradation, chemical degradation of batteries also plays an important role in deciding battery cycle life. The instability of commonly employed electrolytes results in solid electrolyte interphase (SEI) formation. Although SEI formation contributes to irreversible capacity loss, the SEI layer is necessary, as it passivates the electrode-electrolyte interface from further solvent decomposition. SEI layer and diffusion induced stresses are inter-dependent and affect each-other. We study coupled chemical-mechanical degradation of electrode materials to understand the capacity fading of the battery with cycling. With the understanding of chemical and mechanical degradation, we develop a simple phenomenological model to predict battery life. On the experimental part we come up with a novel concept of using liquid metal alloy as a self-healing battery electrode. We develop a method to prepare thin film liquid gallium electrode on a conductive substrate. This enabled us to perform a series of electrochemical and characterization experiments which certify that liquid electrode undergo liquid-solid-liquid transition and thus self-heals the cracks formed during de-insertion. Thus the mechanical degradation can be avoided. We also perform ab-initio calculations to understand the equilibrium potential of various lithium-gallium phases. KEYWORDS: Lithium ion batteries, diffusion induced stresses, self-healing electrode, coupled chemical and mechanical degradation, life-prediction model.

Working underground: Respiratory adaptations in the blind mole rat

PubMed Central

Widmer, Hans R.; Hoppeler, Hans; Nevo, Eviatar; Taylor, C. Richard; Weibel, Ewald R.

1997-01-01

Mole rats (Spalax ehrenbergi superspecies) perform the heavy work of digging their subterranean burrows in Israel under highly hypoxic/hypercapnic conditions. Unlike most other mammals, they can achieve high levels of metabolic rate under these conditions, while their metabolic rate at low work rates is depressed. We explored, by comparing mole rats with white rats, whether and how this is related to adaptations in the design of the respiratory system, which determines the transfer of O2 from the lung to muscle mitochondria. At the same body mass, mole rats were found to have a significantly smaller total skeletal muscle mass than ordinary white rats (−22%). In contrast, the fractional volume of muscle mitochondria was larger by 46%. As a consequence, both species had the same total amount of mitochondria and achieved, under normoxia, the same V̇O2max. Whereas the O2 transport capacity of the blood was not different, we found a larger capillary density (+31%) in the mole rat muscle, resulting in a reduced diffusion distance to mitochondria. The structural pulmonary diffusing capacity for O2 was greater in the mole rat (+44%), thus facilitating O2 uptake in hypoxia. We conclude that structural adaptations in lung and muscle tissue improve O2 diffusion conditions and serve to maintain high metabolic rates in hypoxia but have no consequences for achieving V̇O2max under normoxic conditions. PMID:9050905

Lung function parameters improve prediction of VO2peak in an elderly population: The Generation 100 study.

PubMed

Hassel, Erlend; Stensvold, Dorthe; Halvorsen, Thomas; Wisløff, Ulrik; Langhammer, Arnulf; Steinshamn, Sigurd

2017-01-01

Peak oxygen uptake (VO2peak) is an indicator of cardiovascular health and a useful tool for risk stratification. Direct measurement of VO2peak is resource-demanding and may be contraindicated. There exist several non-exercise models to estimate VO2peak that utilize easily obtainable health parameters, but none of them includes lung function measures or hemoglobin concentrations. We aimed to test whether addition of these parameters could improve prediction of VO2peak compared to an established model that includes age, waist circumference, self-reported physical activity and resting heart rate. We included 1431 subjects aged 69-77 years that completed a laboratory test of VO2peak, spirometry, and a gas diffusion test. Prediction models for VO2peak were developed with multiple linear regression, and goodness of fit was evaluated. Forced expiratory volume in one second (FEV1), diffusing capacity of the lung for carbon monoxide and blood hemoglobin concentration significantly improved the ability of the established model to predict VO2peak. The explained variance of the model increased from 31% to 48% for men and from 32% to 38% for women (p<0.001). FEV1, diffusing capacity of the lungs for carbon monoxide and hemoglobin concentration substantially improved the accuracy of VO2peak prediction when added to an established model in an elderly population.

Improved anode materials for lithium-ion batteries comprise non-covalently bonded graphene and silicon nanoparticles

NASA Astrophysics Data System (ADS)

Ye, Yun-Sheng; Xie, Xiao-Lin; Rick, John; Chang, Feng-Chih; Hwang, Bing-Joe

2014-02-01

Si, when compared to conventional graphite, offers an order-of-magnitude improvement as a high capacity anode material for Li-ion batteries. Despite significant advances in nanostructured Si-based anodes, the formation of stable Si anodes remains a challenge, due to the significant volume changes that occur during lithiation and delithiation. Si/graphene composites, with graphene sheets and Si nanoparticles bound in a dispersion obtained by a self-assembly technique using non-covalent electrostatic attraction (following thermal processing to remove residual organic material) are used to prepare Si-based anodes for use in Li-ion batteries. A mesoporous structure, obtained by further thermal processing is able to accommodate large Si nanoparticle volume changes during cycling, thereby facilitating Li-ion diffusion within the electrode. Morphological analysis showed that Si nanoparticles are homogeneously distributed on the graphene sheets, which is thought to account for the excellent electrochemical performance of the resulting Si/graphene composite. A composite containing Si 67.3 wt% exhibits a greatly improved capacity and cycling stability in comparison with bare Si in combination with the thermal reduction of a simple mixture of graphene oxide and Si nanoparticles without electrostatic attraction (Si content = 64.6 wt%; capacity of 512 mAh g-1 in 40th cycle).

Recent Progress in Synthesis and Application of Low-Dimensional Silicon Based Anode Material for Lithium Ion Battery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Yuandong; Liu, Kewei; Zhu, Yu

Silicon is regarded as the next generation anode material for LIBs with its ultra-high theoretical capacity and abundance. Nevertheless, the severe capacity degradation resulting from the huge volume change and accumulative solid-electrolyte interphase (SEI) formation hinders the silicon based anode material for further practical applications. Hence, a variety of methods have been applied to enhance electrochemical performances in terms of the electrochemical stability and rate performance of the silicon anodes such as designing nanostructured Si, combining with carbonaceous material, exploring multifunctional polymer binders, and developing artificial SEI layers. Silicon anodes with low-dimensional structures (0D, 1D, and 2D), compared with bulkymore » silicon anodes, are strongly believed to have several advanced characteristics including larger surface area, fast electron transfer, and shortened lithium diffusion pathway as well as better accommodation with volume changes, which leads to improved electrochemical behaviors. Finally, in this review, recent progress of silicon anode synthesis methodologies generating low-dimensional structures for lithium ion batteries (LIBs) applications is listed and discussed.« less

Recent Progress in Synthesis and Application of Low-Dimensional Silicon Based Anode Material for Lithium Ion Battery

DOE PAGES

Sun, Yuandong; Liu, Kewei; Zhu, Yu

2017-07-31

Silicon is regarded as the next generation anode material for LIBs with its ultra-high theoretical capacity and abundance. Nevertheless, the severe capacity degradation resulting from the huge volume change and accumulative solid-electrolyte interphase (SEI) formation hinders the silicon based anode material for further practical applications. Hence, a variety of methods have been applied to enhance electrochemical performances in terms of the electrochemical stability and rate performance of the silicon anodes such as designing nanostructured Si, combining with carbonaceous material, exploring multifunctional polymer binders, and developing artificial SEI layers. Silicon anodes with low-dimensional structures (0D, 1D, and 2D), compared with bulkymore » silicon anodes, are strongly believed to have several advanced characteristics including larger surface area, fast electron transfer, and shortened lithium diffusion pathway as well as better accommodation with volume changes, which leads to improved electrochemical behaviors. Finally, in this review, recent progress of silicon anode synthesis methodologies generating low-dimensional structures for lithium ion batteries (LIBs) applications is listed and discussed.« less

Thermophysical Properties of Solid and Liquid Ti-6Al-4V (TA6V) Alloy

NASA Astrophysics Data System (ADS)

Boivineau, M.; Cagran, C.; Doytier, D.; Eyraud, V.; Nadal, M.-H.; Wilthan, B.; Pottlacher, G.

2006-03-01

Ti-6Al-4V (TA6V) titanium alloy is widely used in industrial applications such as aeronautic and aerospace due to its good mechanical properties at high temperatures. Experiments on two different resistive pulse heating devices (CEA Valduc and TU-Graz) have been carried out in order to study thermophysical properties (such as electrical resistivity, volume expansion, heat of fusion, heat capacity, normal spectral emissivity, thermal diffusivity, and thermal conductivity) of both solid and liquid Ti-6Al-4V. Fast time-resolved measurements of current, voltage, and surface radiation and shadowgraphs of the volume have been undertaken. At TU-Graz, a fast laser polarimeter has been used for determining the emissivity of liquid Ti-6Al-4V at 684.5 nm and a differential scanning calorimeter (DSC) for measuring the heat capacity of solid Ti-6Al-4V. This study deals with the specific behavior of the different solid phase transitions (effect of heating rate) and the melting region, and emphasizes the liquid state ( T > 2000 K).

Characterization of large-pore polymeric supports for use in perfusion biochromatography.

PubMed

Whitney, D; McCoy, M; Gordon, N; Afeyan, N

1998-05-22

Perfusion chromatography is uniquely characterized by the flow of a portion of the column eluent directly through the resin in the packed bed. The benefits of this phenomenon and some of the properties of perfusive resins have been described before, and can be summarized as enhanced mass transport to interior binding sites. Here we extend the understanding of this phenomenon by comparing resins with different pore size distributions. Resins are chosen to give approximately the same specific pore volumes (as shown in the characterization section) but the varying contribution of large pores is used to control the amount of liquid flowing through the beads. POROS R1 has the largest contribution of throughpores, and therefore the greatest intraparticle flow. POROS R2 has a lower contribution of throughpores, and a higher surface area coming from a greater population of diffusive pores, but still shows significant mass transport enhancements relative to a purely diffusive control. Oligo R3 is dominated by a high population of diffusive pores, and is used comparatively as a non-perfusive resin. Although the pore size distribution can be engineered to control mass transport rates, the resulting surface area is not the only means by which binding capacity can be controlled. Surface coatings are employed to increase binding capacity without fundamentally altering the mass transport properties. Models are used to describe the amount of flow transecting the beads, and comparisons of coated resins to uncoated (polystyrene) resins leads to the conclusion that these coatings do not obstruct the throughpore structures. This is an important conclusion since the binding capacity of the coated product, in some cases, is shown to be over 10-fold higher than the precursor polystyrene scaffold (i.e., POROS R1 or POROS R2).

The Nature of Electrochemical Delithiation of Li-Mg Alloy Electrodes: Neutron Computed Tomography and Modeling of Li Diffusion and Delithiation Phenomenon

DOE PAGES

Zhang, Yuxuan; Chandran, K.S. Ravi; Jagannathan, M.; ...

2016-12-05

Li-Mg alloys are promising as positive electrodes (anodes) for Li-ion batteries due to the high Li storage capacity and the relatively lower volume change during the lithiation/delithiation process. They also present a unique opportunity to image the Li distribution through the electrode thickness at various delithiation states. In this work, spatial distributions of Li in electrochemically delithiated Li-Mg alloy electrodes have been quantitatively determined using neutron tomography. Specifically, the Li concentration profiles along thickness direction are determined. A rigorous analytical model to quantify the diffusion-controlled delithiation, accompanied by phase transition and boundary movement, has also been developed to explain themore » delithiation mechanism. The analytical modeling scheme successfully predicted the Li concentration profiles which agreed well with the experimental data. It is demonstrated that during discharge Li is removed by diffusion through the solid solution Li-Mg phases and this proceeds with β→α phase transition and the associated phase boundary movement through the thickness of the electrode. This is also accompanied by electrode thinning due to the change in molar volume during delithiation. In conclusion, following the approaches developed here, one can develop a rigorous and quantitative understanding of electrochemical delithiation in electrodes of electrochemical cells, similar to that in the present Li-Mg electrodes.« less

The Nature of Electrochemical Delithiation of Li-Mg Alloy Electrodes: Neutron Computed Tomography and Modeling of Li Diffusion and Delithiation Phenomenon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yuxuan; Chandran, K.S. Ravi; Jagannathan, M.

Li-Mg alloys are promising as positive electrodes (anodes) for Li-ion batteries due to the high Li storage capacity and the relatively lower volume change during the lithiation/delithiation process. They also present a unique opportunity to image the Li distribution through the electrode thickness at various delithiation states. In this work, spatial distributions of Li in electrochemically delithiated Li-Mg alloy electrodes have been quantitatively determined using neutron tomography. Specifically, the Li concentration profiles along thickness direction are determined. A rigorous analytical model to quantify the diffusion-controlled delithiation, accompanied by phase transition and boundary movement, has also been developed to explain themore » delithiation mechanism. The analytical modeling scheme successfully predicted the Li concentration profiles which agreed well with the experimental data. It is demonstrated that during discharge Li is removed by diffusion through the solid solution Li-Mg phases and this proceeds with β→α phase transition and the associated phase boundary movement through the thickness of the electrode. This is also accompanied by electrode thinning due to the change in molar volume during delithiation. In conclusion, following the approaches developed here, one can develop a rigorous and quantitative understanding of electrochemical delithiation in electrodes of electrochemical cells, similar to that in the present Li-Mg electrodes.« less

Factors influencing the measurement of closing volume.

PubMed

Make, B; Lapp, N L

1975-06-01

The various factors influencing closing volume were studied by performing the single-breath N2 test on 9 healthy nonsmokers. Time of day, day of the week, and preceding volume history had no effect on either closing volume or alveolar plateau. Slow inspiratory flow resulted in larger ratio of closing volume to vital capacity, ratio of closing capacity to total lung capacity, and change in N2 concentration than fast inspiratory flow. Voluntary regulation of the expiratory flow resulted in smaller ratios of closing volume to vital capacity and closing capacity to total lung capacity than when flow was regulated by a resistance. Prolonged breath holding of the inspired O2 led to larger ratio of closing volume to vital capacity and ratio of closing capacity to total lung capacity. To obtain uniform, comparable closing volumes, it is suggested that the subject inspire slowly, control expiratory flow (preferably voluntarily), and not pause between inspiration and expiration.

Cardiopulmonary involvement in Fabry's disease.

PubMed

Koskenvuo, Juha W; Kantola, Ilkka M; Nuutila, Pirjo; Knuuti, Juhani; Parkkola, Riitta; Mononen, Ilkka; Hurme, Saija; Kalliokoski, Riikka; Viikari, Jorma S; Wendelin-Saarenhovi, Maria; Kiviniemi, Tuomas O; Hartiala, Jaakko J

2010-04-01

Fabry's disease is an X-linked lysosomal storage disease caused by deficiency of alpha-galactosidase A enzyme activity. Decreased enzyme activity leads to accumulation of glycosphingolipid in different tissues, including endothelial and smooth-muscle cells and cardiomyocytes. There is controversial data on cardiopulmonary involvement in Fabry's disease, because many reports are based on small and selected populations with Fabry's disease. Furthermore, the aetiology of cardiopulmonary symptoms in Fabry's disease is poorly understood. We studied cardiopulmonary involvement in seventeen patients with Fabry's disease (20-65 years, 6 men) using ECG, bicycle stress, cardiac magnetic resonance imaging, spirometry, diffusing capacity and pulmonary high-resolution computed tomography (HRCT) tests. Cardiopulmonary symptoms were compared to observed parameters in cardiopulmonary tests. Left ventricular hypertrophy (LVH) and reduced exercise capacity are the most apparent cardiac changes in both genders with Fabry's disease. ECG parameters were normal when excluding changes related to LVH. Spirometry showed mild reduction in vital capacity and forced expiratory volume in one second (FEV I), and mean values in diffusing capacity tests were within normal limits. Generally, only slight morphological pulmonary changes were detected using pulmonary HRCT, and they were not associated with changes in pulmonary function. The self-reported amount of pulmonary symptoms associated only with lower ejection fraction (P < 0.001) and longer QRS-duration (P = 0.04) of all measured cardiopulmonary parameters, whereas cardiac symptoms have no statistically significant association with any of these parameters. LVH and reduced exercise capacity are the most apparent cardiopulmonary changes in Fabry's disease but they have only a minor association to cardiopulmonary symptoms.Therefore, routine cardiopulmonary evaluation in Fabry's disease using echocardiography is maybe enough when integrated to counselling for aerobic exercise training.

Comments on the Diffusive Behavior of Two Upwind Schemes

NASA Technical Reports Server (NTRS)

Wood, William A.; Kleb, William L.

1998-01-01

The diffusive characteristics of two upwind schemes, multi-dimensional fluctuation splitting and locally one-dimensional finite volume, are compared for scalar advection-diffusion problems. Algorithms for the two schemes are developed for node-based data representation on median-dual meshes associated with unstructured triangulations in two spatial dimensions. Four model equations are considered: linear advection, non-linear advection, diffusion, and advection-diffusion. Modular coding is employed to isolate the effects of the two approaches for upwind flux evaluation, allowing for head-to-head accuracy and efficiency comparisons. Both the stability of compressive limiters and the amount of artificial diffusion generated by the schemes is found to be grid-orientation dependent, with the fluctuation splitting scheme producing less artificial diffusion than the finite volume scheme. Convergence rates are compared for the combined advection-diffusion problem, with a speedup of 2.5 seen for fluctuation splitting versus finite volume when solved on the same mesh. However, accurate solutions to problems with small diffusion coefficients can be achieved on coarser meshes using fluctuation splitting rather than finite volume, so that when comparing convergence rates to reach a given accuracy, fluctuation splitting shows a speedup of 29 over finite volume.

Diffusion Characteristics of Upwind Schemes on Unstructured Triangulations

NASA Technical Reports Server (NTRS)

Wood, William A.; Kleb, William L.

1998-01-01

The diffusive characteristics of two upwind schemes, multi-dimensional fluctuation splitting and dimensionally-split finite volume, are compared for scalar advection-diffusion problems. Algorithms for the two schemes are developed for node-based data representation on median-dual meshes associated with unstructured triangulations in two spatial dimensions. Four model equations are considered: linear advection, non-linear advection, diffusion, and advection-diffusion. Modular coding is employed to isolate the effects of the two approaches for upwind flux evaluation, allowing for head-to-head accuracy and efficiency comparisons. Both the stability of compressive limiters and the amount of artificial diffusion generated by the schemes is found to be grid-orientation dependent, with the fluctuation splitting scheme producing less artificial diffusion than the dimensionally-split finite volume scheme. Convergence rates are compared for the combined advection-diffusion problem, with a speedup of 2-3 seen for fluctuation splitting versus finite volume when solved on the same mesh. However, accurate solutions to problems with small diffusion coefficients can be achieved on coarser meshes using fluctuation splitting rather than finite volume, so that when comparing convergence rates to reach a given accuracy, fluctuation splitting shows a 20-25 speedup over finite volume.

Finite-volume scheme for anisotropic diffusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Es, Bram van, E-mail: bramiozo@gmail.com; FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, The Netherlands"1; Koren, Barry

In this paper, we apply a special finite-volume scheme, limited to smooth temperature distributions and Cartesian grids, to test the importance of connectivity of the finite volumes. The area of application is nuclear fusion plasma with field line aligned temperature gradients and extreme anisotropy. We apply the scheme to the anisotropic heat-conduction equation, and compare its results with those of existing finite-volume schemes for anisotropic diffusion. Also, we introduce a general model adaptation of the steady diffusion equation for extremely anisotropic diffusion problems with closed field lines.

Influence of electrolyte composition and temperature on behaviour of AB5 hydrogen storage alloy used as negative electrode in Ni-MH batteries

NASA Astrophysics Data System (ADS)

Karwowska, Malgorzata; Jaron, Tomasz; Fijalkowski, Karol J.; Leszczynski, Piotr J.; Rogulski, Zbigniew; Czerwinski, Andrzej

2014-10-01

The AB5-type metal alloy (Mm-Ni4.1Al0.2Mn0.4Co0.45) has been investigated in different electrolytes (LiOH, NaOH, KOH, RbOH, CsOH). All of the electrochemical measurements have been performed using limited volume electrode technique (LVE). Thickness of the working electrode is nearly equal to the diameter of the grain (ca. 50 μm). Hydrogen diffusion coefficient has been determined using chronoamperometry. Hydrogen diffusion coefficient calculated for 100% state of charge reaches maximum value in KOH (DH = 4.65·10-10 cm2 s-1). We have obtained the highest value of capacity for the electrode in KOH and the lowest - in CsOH. The temperature influence on alloy capacity has been also tested. The alloy has been also characterised with SEM coupled with EDS, TGA/DSC and powder XRD. The unit cell of MmNi4.1Al0.2Mn0.4Co0.45 have been refined in the Cu5.4Yb0.8 structure type (a modified LaNi5 structure); the structure is unaffected by the electrochemical treatment.

Improving the performance of lithium-sulfur batteries by graphene coating

NASA Astrophysics Data System (ADS)

Zhou, Xiangyang; Xie, Jing; Yang, Juan; Zou, Youlan; Tang, Jingjing; Wang, Songcan; Ma, Lulu; Liao, Qunchao

2013-12-01

A graphene coating mesoporous carbon/sulfur (RGO@CMK-3/S) composite, which is characteristic of a hybrid structure by incorporating the merits of CMK-3 matrix and graphene (RGO) skin, is synthesized by a facile and scalable route. The CMK-3/S composite is synthesized via a simple melt-diffusion strategy, and then a thin RGO skin is absorbed on the CMK-3/S composite surface in aqueous solution. When evaluating the electrochemical properties of as-prepared RGO wrapped nanostructures as cathode materials in lithium-sulfur batteries, it exhibits much improved cyclical stability and high rate performance. The RGO@CMK-3/S composite with 53.14 wt.% sulfur presents a reversible discharge capacity of about 734 mA h g-1 after 100 cycles at 0.5 C. The improved performance is attributed to the unique structure of RGO@CMK-3/S composite. CMK-3 with extensively mesopores can offer buffering space for the volume change of sulfur and efficient diffusion channel for lithium ions during the charge/discharge process. Meanwhile, the conductive RGO coating skin physically and chemically prevents the dissolution of polysulfides from the cathode, both of which contribute to the reduced capacity fade and improved electrochemical properties.

Diffusing capacity and forced vital capacity in 5,003 asbestos-exposed workers: relationships to interstitial fibrosis (ILO profusion score) and pleural thickening.

PubMed

Miller, Albert; Warshaw, Raphael; Nezamis, James

2013-12-01

Asbestosis is an interstitial lung disease whose radiographic severity has long been graded by the International Labour Office (ILO) profusion score. Its effect on pulmonary function is further impacted by asbestos related pleural thickening. This report aims to describe the relationships between radiographic grading of interstitial and pleural fibrosis and a key test of pulmonary function, the diffusing capacity, which measures gas exchange and has rarely been assessed in large groups, and to confirm the relationship to an independent test of pulmonary function, the vital capacity, which measures a mechanical property of the lungs. The data were derived from a survey during the period 1997-2004 of 5,003 workers (all white males) exposed to asbestos in various trades. Tests included chest radiographs read by a certified expert ("B") reader, forced vital capacity (FVC), and carbon monoxide diffusing capacity (DLco). Cigarette smoking was adjusted for in the predictive equation for DLCO . Workers were evaluated at a mobile facility at work sites in four southern states. Both diffusing capacity and vital capacity were negatively correlated with profusion score over the full spectrum of radiographic severity. ILO profusion scores 0/1 (conventionally classified as normal) and 1/0 (conventionally classified as abnormal) were associated with similar diffusing capacity and vital capacity values. The highest profusion scores were associated with a greater proportionate decrease in diffusing capacity than in FVC. Both tests showed an effect of pleural fibrosis. Both radiographic severity graded by the profusion score and pleural thickening are correlated with two independent measures of pulmonary function. FVC (which had been reported in smaller work forces) and DLCO (which has not been reported). Both measures show a decrease from normal to intermediate (0/1, 1/0) scores and a further decrease with greater scores, demonstrating the consistency of radiographic and functional assessments. © 2013 Wiley Periodicals, Inc.

Amorphous mesoporous GeO x anode for Na-ion batteries with high capacity and long lifespan.

PubMed

Shen, Kangze; Lin, Ning; Xu, Tianjun; Han, Ying; Qian, Yitai

2018-01-01

It is recently demonstrated that amorphous Ge anode shows higher reversible Na-ion storage capacity (590 mA h g -1 ) than crystallized Ge anode (369 mA h g -1 ). Here, amorphous GeO x anode is prepared by a simple wet-chemistry reduction route at room temperature. The obtained amorphous GeO x shows a porous hierarchical architecture, accompanied with a Brunauer-Emmett-Teller surface area of 159 m 2  g -1 and an average pore diameter of 14 nm. This unique structure enables the GeO x anode to enhance the Na-ion/electron diffusion rate, and buffer the volume change. As anode for Na-ion battery, high reversible capacity over 400 mA h g -1 , fine rate capability with a capacity of 200 mA h g -1 maintained at 3.0 A g -1 and long-term cycling stability with 270 mA h g -1 even over 1000 cycles at 1.0 A g -1 are obtained.

Bronchoscopic Thermal Vapor Ablation: Best Practice Recommendations from an Expert Panel on Endoscopic Lung Volume Reduction.

PubMed

Gompelmann, Daniela; Shah, Pallav L; Valipour, Arschang; Herth, Felix J F

2018-06-12

Bronchoscopic thermal vapor ablation (BTVA) represents one of the endoscopic lung volume reduction (ELVR) techniques that aims at hyperinflation reduction in patients with advanced emphysema to improve respiratory mechanics. By targeted segmental vapor ablation, an inflammatory response leads to tissue and volume reduction of the most diseased emphysematous segments. So far, BTVA has been demonstrated in several single-arm trials and 1 multinational randomized controlled trial to improve lung function, exercise capacity, and quality of life in patients with upper lobe-predominant emphysema irrespective of the collateral ventilation. In this review, we emphasize the practical aspects of this ELVR method. Patients with upper lobe-predominant emphysema, forced expiratory volume in 1 second (FEV1) between 20 and 45% of predicted, residual volume (RV) > 175% of predicted, and carbon monoxide diffusing capacity (DLCO) ≥20% of predicted can be considered for BTVA treatment. Prior to the procedure, a special software assists in identifying the target segments with the highest emphysema index, volume and the highest heterogeneity index to the untreated ipsilateral lung lobes. The procedure may be performed under deep sedation or preferably under general anesthesia. After positioning of the BTVA catheter and occlusion of the target segment by the occlusion balloon, heated water vapor is delivered in a predetermined specified time according to the vapor dose. After the procedure, patients should be strictly monitored to proactively detect symptoms of localized inflammatory reaction that may temporarily worsen the clinical status of the patient and to detect complications. As the data are still very limited, BTVA should be performed within clinical trials or comprehensive registries where the product is commercially available. © 2018 S. Karger AG, Basel.

Heliox Improves Carbon Dioxide Removal during Lung Protective Mechanical Ventilation.

PubMed

Beurskens, Charlotte J; Brevoord, Daniel; Lagrand, Wim K; van den Bergh, Walter M; Vroom, Margreeth B; Preckel, Benedikt; Horn, Janneke; Juffermans, Nicole P

2014-01-01

Introduction. Helium is a noble gas with low density and increased carbon dioxide (CO2) diffusion capacity. This allows lower driving pressures in mechanical ventilation and increased CO2 diffusion. We hypothesized that heliox facilitates ventilation in patients during lung-protective mechanical ventilation using low tidal volumes. Methods. This is an observational cohort substudy of a single arm intervention study. Twenty-four ICU patients were included, who were admitted after a cardiac arrest and mechanically ventilated for 3 hours with heliox (50% helium; 50% oxygen). A fixed protective ventilation protocol (6 mL/kg) was used, with prospective observation for changes in lung mechanics and gas exchange. Statistics was by Bonferroni post-hoc correction with statistical significance set at P < 0.017. Results. During heliox ventilation, respiratory rate decreased (25 ± 4 versus 23 ± 5 breaths min(-1), P = 0.010). Minute volume ventilation showed a trend to decrease compared to baseline (11.1 ± 1.9 versus 9.9 ± 2.1 L min(-1), P = 0.026), while reducing PaCO2 levels (5.0 ± 0.6 versus 4.5 ± 0.6 kPa, P = 0.011) and peak pressures (21.1 ± 3.3 versus 19.8 ± 3.2 cm H2O, P = 0.024). Conclusions. Heliox improved CO2 elimination while allowing reduced minute volume ventilation in adult patients during protective mechanical ventilation.

Tracheole investment does not vary with body size among bumblebee (Bombus impatiens) sisters.

PubMed

Vogt, Jessica R; Dillon, Megan K; Dillon, Michael E

2014-08-01

Body size is a key organism trait with critical implications for the physiology, life history, and ecology of organisms. Modern insects vary in body mass by over 6 orders of magnitude, but are small by comparison to many other metazoan taxa. The small size of modern insects may reflect limitations imposed by their open respiratory systems which rely, in part, on diffusion. Diffusion rates decline with distance such that, absent compensation, the capacity for larger insects to deliver oxygen to their tissues may be compromised. To compensate, larger grasshoppers, beetles, and bumblebees devote proportionally more of their body volume to the respiratory system, as demonstrated by hypermetric scaling of tracheal volume with body mass(>1). Among bumblebee sisters, total respiratory volume scaled with mass(2.6), but it is unclear at what level or levels of the tracheal system (main tracheal trunks, air sacs, tracheoles) bumblebees express this extreme hypermetry. Here we use transmission electron microscopy to examine the morphology of tracheoles in bumblebee flight muscle among sister bumblebees varying nearly four-fold in body mass. Neither tracheole density nor tracheole diameter changed with body mass. The total cross-sectional area of tracheoles was also invariant with body mass. Together, these results reveal that bumblebees do not compensate for size-related limitations on oxygen delivery by increasing investment at the level of the tracheoles. Copyright © 2014 Elsevier Inc. All rights reserved.

Heat capacities and thermal diffusivities of n-alkane acid ethyl esters—biodiesel fuel components

NASA Astrophysics Data System (ADS)

Bogatishcheva, N. S.; Faizullin, M. Z.; Nikitin, E. D.

2017-09-01

The heat capacities and thermal diffusivities of ethyl esters of liquid n-alkane acids C n H2 n-1O2C2H5 with the number of carbon atoms in the parent acid n = 10, 11, 12, 14, and 16 are measured. The heat capacities are measured using a DSC 204 F1 Phoenix heat flux differential scanning calorimeter (Netzsch, Germany) in the temperature range of 305-375 K. Thermal diffusivities are measured by means of laser flash method on an LFA-457 instrument (Netzsch, Germany) at temperatures of 305-400 K. An equation is derived for the dependence of the molar heat capacities of the investigated esters on temperature. It is shown that the dependence of molar heat capacity C p,m (298.15 K) on n ( n = 1-6) is close to linear. The dependence of thermal diffusivity on temperature in the investigated temperature range is described by a first-degree polynomial, but thermal diffusivity a (298.15 K) as a function of n has a minimum at n = 5.

Alternation in the gap-junctional intercellular communication capacity during the maturation of osteocytes in the embryonic chick calvaria.

PubMed

Wang, Ziyi; Odagaki, Naoya; Tanaka, Tomoyo; Hashimoto, Mana; Nakamura, Masahiro; Hayano, Satoru; Ishihara, Yoshihito; Kawanabe, Noriaki; Kamioka, Hiroshi

2016-10-01

The intercellular network of cell-cell communication among osteocytes is mediated by gap junctions. Gap junctional intercellular communication (GJIC) is thought to play an important role in the integration and synchronization of bone remodeling. To further understand the mechanism of bone development it is important to quantify the difference in the GJIC capacity of young and developmentally mature osteocytes. We first established an embryonic chick calvaria growth model to show the growth of the calvaria in embryos at 13 to 21days of age. We then applied a fluorescence recovery after photobleaching (FRAP) technique to compare the difference in the GJIC capacity of young osteocytes with that of developmentally mature osteocytes. Finally, we quantified the dye (Calcein) diffusion from the FRAP data using a mathematic model of simple diffusion which was also used to identify simple diffusion GJIC pattern cells (fitted model) and accelerated diffusion GJIC pattern cells (non-fitted model). The relationship between the longest medial-lateral length of the calvaria (frontal bone) and the embryonic age fit a logarithmic growth model: length=5.144×ln(day)-11.340. The morphometric data during osteocyte differentiation showed that the cellular body becomes more spindle-shaped and that the cell body volume decreased by approximately 22% with an increase in the length of the processes between the cells. However, there were no significant differences in the cellular body surface area or in the distance between the mass centres of the cells. The dye-displacement rate in young osteocytes was significantly higher than that in developmentally mature osteocytes: dye displacement only occurred in 26.88% of the developmentally mature osteocytes, while it occurred in 64.38% of the young osteocytes. Additionally, in all recovered osteocytes, 36% of the developmentally mature osteocytes comprised non-fitted model cells while 53.19% of the young osteocytes were the non-fitted model, which indicates the active transduction of dye molecules. However, there were no statistically significant differences between the young and developmentally mature osteocytes with regard to the diffusion coefficient, permeability coefficient, or permeance of the osteocyte processes, which were 3.93±3.77 (×10(-8)cm(2)/s), 5.12±4.56 (×10(-5)cm(2)/s) and 2.99±2.47 (×10(-13)cm(2)/s) (mean±SD), respectively. These experiments comprehensively quantified the GJIC capacity in the embryonic chick calvaria and indicated that the cell-cell communication capacity of the osteocytes in the embryonic chick calvaria was related to their development. Copyright © 2016 Elsevier Inc. All rights reserved.

Altered contralateral sensorimotor system organization after experimental hemispherectomy: a structural and functional connectivity study.

PubMed

Otte, Willem M; van der Marel, Kajo; van Meer, Maurits P A; van Rijen, Peter C; Gosselaar, Peter H; Braun, Kees P J; Dijkhuizen, Rick M

2015-08-01

Hemispherectomy is often followed by remarkable recovery of cognitive and motor functions. This reflects plastic capacities of the remaining hemisphere, involving large-scale structural and functional adaptations. Better understanding of these adaptations may (1) provide new insights in the neuronal configuration and rewiring that underlies sensorimotor outcome restoration, and (2) guide development of rehabilitation strategies to enhance recovery after hemispheric lesioning. We assessed brain structure and function in a hemispherectomy model. With MRI we mapped changes in white matter structural integrity and gray matter functional connectivity in eight hemispherectomized rats, compared with 12 controls. Behavioral testing involved sensorimotor performance scoring. Diffusion tensor imaging and resting-state functional magnetic resonance imaging were acquired 7 and 49 days post surgery. Hemispherectomy caused significant sensorimotor deficits that largely recovered within 2 weeks. During the recovery period, fractional anisotropy was maintained and white matter volume and axial diffusivity increased in the contralateral cerebral peduncle, suggestive of preserved or improved white matter integrity despite overall reduced white matter volume. This was accompanied by functional adaptations in the contralateral sensorimotor network. The observed white matter modifications and reorganization of functional network regions may provide handles for rehabilitation strategies improving functional recovery following large lesions.

Portsmouth Gaseous Diffusion Plant expansion: final environmental statement. Volume 2. Appendices. [Appendices only

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liverman, James L.

Volume 2 is comprised of appendices: Portsmouth Gaseous Diffusion Plant Existing Facilities; Ecology; Civic Involvement; Social Analysis; Population Projections; Toxicity of Air Pollutants to Biota at Portsmouth Gaseous Diffusion Plant; and Assessment of Noise Effects of an Add-On to the Portsmouth Gaseous Diffusion Plant. (LK)

Low haemoglobin concentration in Tibetan males is associated with greater high-altitude exercise capacity.

PubMed

Simonson, T S; Wei, G; Wagner, H E; Wuren, T; Qin, G; Yan, M; Wagner, P D; Ge, R L

2015-07-15

Tibetans living at high altitude have adapted genetically such that many display a low erythropoietic response, resulting in near sea-level haemoglobin (Hb) concentration. We hypothesized that absence of the erythropoietic response would be associated with greater exercise capacity compared to those with high [Hb] as a result of beneficial changes in oxygen transport. We measured, in 21 Tibetan males with [Hb] ranging from 15.2 g dl(-1) to 22.9 g dl(-1) (9.4 mmol l(-1) to 14.2 mmol l(-1) ), [Hb], ventilation, volumes of O2 and CO2 utilized at peak exercise (V̇O2 and V̇CO2), heart rate, cardiac output and arterial blood gas variables at peak exercise on a cycle ergometer at ∼4200 m. Lung and muscle O2 diffusional conductances were computed from these measurements. [Hb] was related (negatively) to V̇O2 kg(-1) (r = -0.45, P< 0.05), cardiac output kg(-1) (QT kg(-1) , r = -0.54, P < 0.02), and O2 diffusion capacity in muscle (DM kg(-1) , r = -0.44, P<0.05), but was unrelated to ventilation, arterial partial pressure of O2 (PaO2) or pulmonary diffusing capacity. Using multiple linear regression, variance in peak V̇O2 kg(-1) was primarily attributed to QT, DM, and PCO2 (R(2) = 0.88). However, variance in pulmonary gas exchange played essentially no role in determining peak V̇O2. These results (1) show higher exercise capacity in Tibetans without the erythropoietic response, supported mostly by cardiac and muscle O2 transport capacity and ventilation rather than pulmonary adaptations, and (2) support the emerging hypothesis that the polycythaemia of altitude, normally a beneficial response to low cellular PO2, may become maladaptive if excessively elevated under chronic hypoxia. The cause and effect relationships among [Hb], QT, DM, and PCO2 remain to be elucidated. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

Bivelocity hydrodynamics. Diffuse mass flux vs. diffuse volume flux

NASA Astrophysics Data System (ADS)

Brenner, Howard

2013-02-01

An intimate physical connection exists between a fluid’s mass and its volume, with the density ρ serving as a proportionality factor relating these two extensive thermodynamic properties when the fluid is homogeneous. This linkage has led to the erroneous belief among many researchers that a fluid’s diffusive (dissipative) mass flux and its diffusive volume flux counterpart, both occurring in inhomogeneous fluids undergoing transport are, in fact, synonymous. However, the existence of a truly dissipative mass flux (that is, a mass flux that is physically dissipative) has recently and convincingly been shown to be a physical impossibility [H.C. Öttinger, H. Struchtrup, M. Liu, On the impossibility of a dissipative contribution to the mass flux in hydrodynamics, Phys. Rev. E 80 (2009) 056303], owing, among other things, to its violation of the principle of angular momentum conservation. Unfortunately, as a consequence of the erroneous belief in the equality of the diffuse volume and mass fluxes (sans an algebraic sign), this has led many researchers to wrongly conclude that a diffuse volume flux is equally impossible. As a consequence, owing to the fundamental role played by the diffuse volume flux in the theory of bivelocity hydrodynamics [H. Brenner, Beyond Navier-Stokes, Int. J. Eng. Sci. 54 (2012) 67-98], many researchers have been led to falsely dismiss, without due consideration, the possibility of bivelocity hydrodynamics constituting a potentially viable physical theory, which it is believed to be. The present paper corrects this misconception by using a simple concrete example involving an isothermal rotating rigid-body fluid motion to clearly confirm that whereas a diffuse mass flux is indeed impossible, this fact does not exclude the possible existence of a diffuse volume flux and, concomitantly, the possibility that bivelocity hydrodynamics is indeed a potentially viable branch of fluid mechanics.

Carrying capacity in a heterogeneous environment with habitat connectivity.

PubMed

Zhang, Bo; Kula, Alex; Mack, Keenan M L; Zhai, Lu; Ryce, Arrix L; Ni, Wei-Ming; DeAngelis, Donald L; Van Dyken, J David

2017-09-01

A large body of theory predicts that populations diffusing in heterogeneous environments reach higher total size than if non-diffusing, and, paradoxically, higher size than in a corresponding homogeneous environment. However, this theory and its assumptions have not been rigorously tested. Here, we extended previous theory to include exploitable resources, proving qualitatively novel results, which we tested experimentally using spatially diffusing laboratory populations of yeast. Consistent with previous theory, we predicted and experimentally observed that spatial diffusion increased total equilibrium population abundance in heterogeneous environments, with the effect size depending on the relationship between r and K. Refuting previous theory, however, we discovered that homogeneously distributed resources support higher total carrying capacity than heterogeneously distributed resources, even with species diffusion. Our results provide rigorous experimental tests of new and old theory, demonstrating how the traditional notion of carrying capacity is ambiguous for populations diffusing in spatially heterogeneous environments. © 2017 John Wiley & Sons Ltd/CNRS.

Carrying capacity in a heterogeneous environment with habitat connectivity

USGS Publications Warehouse

Zhang, Bo; Kula, Alex; Mack, Keenan M.L.; Zhai, Lu; Ryce, Arrix L.; Ni, Wei-Ming; DeAngelis, Donald L.; Van Dyken, J. David

2017-01-01

A large body of theory predicts that populations diffusing in heterogeneous environments reach higher total size than if non-diffusing, and, paradoxically, higher size than in a corresponding homogeneous environment. However, this theory and its assumptions have not been rigorously tested. Here, we extended previous theory to include exploitable resources, proving qualitatively novel results, which we tested experimentally using spatially diffusing laboratory populations of yeast. Consistent with previous theory, we predicted and experimentally observed that spatial diffusion increased total equilibrium population abundance in heterogeneous environments, with the effect size depending on the relationship between r and K. Refuting previous theory, however, we discovered that homogeneously distributed resources support higher total carrying capacity than heterogeneously distributed resources, even with species diffusion. Our results provide rigorous experimental tests of new and old theory, demonstrating how the traditional notion of carrying capacity is ambiguous for populations diffusing in spatially heterogeneous environments.

[Comparative study of respiratory exchanging surfaces in birds and mammals].

PubMed

Jammes, Y

1975-01-01

Anatomical studies of the respiratory apparatus of birds show evidences for a gas exchanging tubular system (parabronchi and air capillaries); these exchanging structures are entirely dissociated from the ventilatory drive acting on the air sacs. A "cross-current" gas exchanging system (perpendicular disposition of air and blood capillaries) allow a good wash-out of carbon dioxide (PaCO2 lower than PECO2). The great efficiency of this lung is allowed by its very large diffusive surface (ASa) and by the high values of lung specific oxygen diffusing capacity (DO2/ASa) and of O2 extraction coefficient in inspired air. The ventilatory pattern of birds is characterized by a greater tidal volume and a smaller respiratory frequency than in mammals of same weight. Respiratory centers of birds receive afferences from lung stretch receptors, CO2-sensitive lung receptors and arterial chemoreceptors.

Diffused holographic information storage and retrieval using photorefractive optical materials

NASA Astrophysics Data System (ADS)

McMillen, Deanna Kay

Holography offers a tremendous opportunity for dense information storage, theoretically one bit per cubic wavelength of material volume, with rapid retrieval, of up to thousands of pages of information simultaneously. However, many factors prevent the theoretical storage limit from being reached, including dynamic range problems and imperfections in recording materials. This research explores new ways of moving closer to practical holographic information storage and retrieval by altering the recording materials, in this case, photorefractive crystals, and by increasing the current storage capacity while improving the information retrieved. As an experimental example of the techniques developed, the information retrieved is the correlation peak from an optical recognition architecture, but the materials and methods developed are applicable to many other holographic information storage systems. Optical correlators can potentially solve any signal or image recognition problem. Military surveillance, fingerprint identification for law enforcement or employee identification, and video games are but a few examples of applications. A major obstacle keeping optical correlators from being universally accepted is the lack of a high quality, thick (high capacity) holographic recording material that operates with red or infrared wavelengths which are available from inexpensive diode lasers. This research addresses the problems from two positions: find a better material for use with diode lasers, and reduce the requirements placed on the material while maintaining an efficient and effective system. This research found that the solutions are new dopants introduced into photorefractive lithium niobate to improve wavelength sensitivities and the use of a novel inexpensive diffuser that reduces the dynamic range and optical element quality requirements (which reduces the cost) while improving performance. A uniquely doped set of 12 lithium niobate crystals was specified and procured for this research. Transmission spectra and diffraction efficiencies were measured for each of the crystals using wavelengths in the visible spectrum. The diffraction efficiency was increased by as much as two orders of magnitude by using a new dopant combination. A new optical diffuser was designed, modeled, fabricated, and tested as a means of improving storage capacity for angularly multiplexed holograms in photorefractive crystals. The diffuser reduced the dynamic range requirement by over three orders of magnitude, increased the storage capacity by more than 400%, and dramatically improved the correlation signals.

An analytical model for pressure of volume fractured tight oil reservoir with horizontal well

NASA Astrophysics Data System (ADS)

Feng, Qihong; Dou, Kaiwen; Zhang, Xianmin; Xing, Xiangdong; Xia, Tian

2017-05-01

The property of tight oil reservoir is worse than common reservoir that we usually seen before, the porosity and permeability is low, the diffusion is very complex. Therefore, the ordinary depletion method is useless here. The volume fracture breaks through the conventional EOR mechanism, which set the target by amplifying the contact area of fracture and reservoir so as to improving the production of every single well. In order to forecast the production effectively, we use the traditional dual-porosity model, build an analytical model for production of volume fractured tight oil reservoir with horizontal well, and get the analytical solution in Laplace domain. Then we construct the log-log plot of dimensionless pressure and time by stiffest conversion. After that, we discuss the influential factors of pressure. Several factors like cross flow, skin factors and threshold pressure gradient was analyzed in the article. This model provides a useful method for tight oil production forecast and it has certain guiding significance for the production capacity prediction and dynamic analysis.

Diffusion coefficient of alginate microcapsules used in pancreatic islet transplantation, a method to cure type 1 diabetes

NASA Astrophysics Data System (ADS)

Najdahmadi, Avid; Lakey, Jonathan R. T.; Botvinick, Elliot

2018-02-01

Pancreatic islet transplantation is a promising approach of providing insulin in type 1 diabetes. One strategy to protect islets from the host immune system is encapsulation within a porous biocompatible alginate membrane. This encapsulation provides mechanical support to the cells and allows selective diffusion of oxygen, nutrients and insulin while blocking immunoglobulins. These hydrogels form by diffusion of calcium ions into the polymer network and therefore they are highly sensitive to environmental changes and fluctuations in temperature. We investigated the effects of gel concentration, crosslinking time and ambient conditions on material permeability, volume, and rigidity, all of which may change the immunoisolating characteristics of alginate. To measure diffusion coefficient as a method to capture structural changes we studied the diffusion of fluorescently tagged dextrans of different molecular weight into the midplane of alginate microcapsules, the diffusion coefficient is then calculated by fitting observed fluorescence dynamics to the mathematical solution of 1-D diffusion into a sphere. These measurements were performed after incubation in different conditions as well as after an in vivo experiment in six immunocompetent mice for seven days. Additionally, the changes in gel volume after incubation at different temperatures and environmental conditions as well as changes in compression modulus of alginate gels during crosslinking were investigated. Our result show that increase of polymer concentration and crosslinking time leads to a decrease in volume and increase in compression modulus. Furthermore, we found that samples crosslinked and placed in physiological environment, experience an increase in volume. As expected, these volume changes affect diffusion rates of fluorescent dextrans, where volume expansion is correlated with higher calculated diffusion coefficient. This observation is critical to islet protection since higher permeability due to the expansion in vivo may lead to increased permeability to immunoglobulins. Capsules from the in vivo study showed similar volume expansion and increased permeability, indicating our in vitro assay is a good predictor of volume change in vivo.

Six minute walking test and carbon monoxide diffusing capacity for non-small cell lung cancer: easy performed tests in every day practice.

PubMed

Zarogoulidis, Paul; Kerenidi, Theodora; Huang, Haidong; Kontakiotis, Theodoros; Tremma, Ourania; Porpodis, Konstantinos; Kalianos, Anastasios; Rapti, Ageliki; Foroulis, Christoforos; Zissimopoulos, Athanasios; Courcoutsakis, Nikolaos; Zarogoulidis, Konstantinos

2012-12-01

Several studies have demonstrated that reduced lung function is a significant risk factor for lung cancer and increased surgical risk in patients with operable stages of lung cancer. The aim of the study was to perform pulmonary function tests and investigate which is a favorable respiratory function test for overall survival between lung cancer stages. Lung function tests were performed to lung cancer patients with non-small cell lung cancer of stage I, II, III and IV (241 patients in total). They had the last follow-up consecutively between December 2006 and July 2008. The staging was decided according to the sixth edition of TNM classification of NSCLC. The Forced Expiratory Volume in 1sec (FEV1), Forced Vital Capacity (FVC) and Carbon Monoxide Diffusing Capacity (DLCO) were measured according to American Thoracic Society/European Respiratory Society guidelines. The 6 Minute Walking Test (6MWT) was measured according to the American Thoracic Society. There was a significant association of the DLCO upon diagnosis and overall survival for stage II (P<0.007) and IV (P<0.003). Furthermore, there was a significant association between 6MWT and overall survival for stage III (P<0.001) and stage IV (P<0.010). The significance for each lung function test is different among the stages of NSCLC. DLCO and 6MWT upon admission are the most valuable prognostic factors for overall survival of NSCLC.

Histogram Analysis of Diffusion Weighted Imaging at 3T is Useful for Prediction of Lymphatic Metastatic Spread, Proliferative Activity, and Cellularity in Thyroid Cancer.

PubMed

Schob, Stefan; Meyer, Hans Jonas; Dieckow, Julia; Pervinder, Bhogal; Pazaitis, Nikolaos; Höhn, Anne Kathrin; Garnov, Nikita; Horvath-Rizea, Diana; Hoffmann, Karl-Titus; Surov, Alexey

2017-04-12

Pre-surgical diffusion weighted imaging (DWI) is increasingly important in the context of thyroid cancer for identification of the optimal treatment strategy. It has exemplarily been shown that DWI at 3T can distinguish undifferentiated from well-differentiated thyroid carcinoma, which has decisive implications for the magnitude of surgery. This study used DWI histogram analysis of whole tumor apparent diffusion coefficient (ADC) maps. The primary aim was to discriminate thyroid carcinomas which had already gained the capacity to metastasize lymphatically from those not yet being able to spread via the lymphatic system. The secondary aim was to reflect prognostically important tumor-biological features like cellularity and proliferative activity with ADC histogram analysis. Fifteen patients with follicular-cell derived thyroid cancer were enrolled. Lymph node status, extent of infiltration of surrounding tissue, and Ki-67 and p53 expression were assessed in these patients. DWI was obtained in a 3T system using b values of 0, 400, and 800 s/mm². Whole tumor ADC volumes were analyzed using a histogram-based approach. Several ADC parameters showed significant correlations with immunohistopathological parameters. Most importantly, ADC histogram skewness and ADC histogram kurtosis were able to differentiate between nodal negative and nodal positive thyroid carcinoma. histogram analysis of whole ADC tumor volumes has the potential to provide valuable information on tumor biology in thyroid carcinoma. However, further studies are warranted.

Histogram Analysis of Diffusion Weighted Imaging at 3T is Useful for Prediction of Lymphatic Metastatic Spread, Proliferative Activity, and Cellularity in Thyroid Cancer

PubMed Central

Schob, Stefan; Meyer, Hans Jonas; Dieckow, Julia; Pervinder, Bhogal; Pazaitis, Nikolaos; Höhn, Anne Kathrin; Garnov, Nikita; Horvath-Rizea, Diana; Hoffmann, Karl-Titus; Surov, Alexey

2017-01-01

Pre-surgical diffusion weighted imaging (DWI) is increasingly important in the context of thyroid cancer for identification of the optimal treatment strategy. It has exemplarily been shown that DWI at 3T can distinguish undifferentiated from well-differentiated thyroid carcinoma, which has decisive implications for the magnitude of surgery. This study used DWI histogram analysis of whole tumor apparent diffusion coefficient (ADC) maps. The primary aim was to discriminate thyroid carcinomas which had already gained the capacity to metastasize lymphatically from those not yet being able to spread via the lymphatic system. The secondary aim was to reflect prognostically important tumor-biological features like cellularity and proliferative activity with ADC histogram analysis. Fifteen patients with follicular-cell derived thyroid cancer were enrolled. Lymph node status, extent of infiltration of surrounding tissue, and Ki-67 and p53 expression were assessed in these patients. DWI was obtained in a 3T system using b values of 0, 400, and 800 s/mm2. Whole tumor ADC volumes were analyzed using a histogram-based approach. Several ADC parameters showed significant correlations with immunohistopathological parameters. Most importantly, ADC histogram skewness and ADC histogram kurtosis were able to differentiate between nodal negative and nodal positive thyroid carcinoma. Conclusions: histogram analysis of whole ADC tumor volumes has the potential to provide valuable information on tumor biology in thyroid carcinoma. However, further studies are warranted. PMID:28417929

Behaviors and kinetics of toluene adsorption-desorption on activated carbons with varying pore structure.

PubMed

Yang, Xi; Yi, Honghong; Tang, Xiaolong; Zhao, Shunzheng; Yang, Zhongyu; Ma, Yueqiang; Feng, Tiecheng; Cui, Xiaoxu

2018-05-01

This work was undertaken to investigate the behaviors and kinetics of toluene adsorption and desorption on activated carbons with varying pore structure. Five kinds of activated carbon from different raw materials were selected. Adsorption isotherms and breakthrough curves for toluene were measured. Langmuir and Freundlich equations were fitted to the equilibrium data, and the Freundlich equation was more suitable for simulating toluene adsorption. The process consisted of monolayer, multilayer and partial active site adsorption types. The effect of the pore structure of the activated carbons on toluene adsorption capacity was investigated. The quasi-first-order model was more suitable for describing the process than the quasi-second-order model. The adsorption data was also modeled by the internal particle diffusion model and it was found that the adsorption process could be divided into three stages. In the external surface adsorption process, the rate depended on the specific surface area. During the particle diffusion stage, pore structure and volume were the main factors affecting adsorption rate. In the final equilibrium stage, the rate was determined by the ratio of meso- and macro-pores to total pore volume. The rate over the whole adsorption process was dominated by the toluene concentration. The desorption behavior of toluene on activated carbons was investigated, and the process was divided into heat and mass transfer parts corresponding to emission and diffusion mechanisms, respectively. Physical adsorption played the main role during the adsorption process. Copyright © 2017. Published by Elsevier B.V.

The physiological basis and clinical significance of lung volume measurements.

PubMed

Lutfi, Mohamed Faisal

2017-01-01

From a physiological standpoint, the lung volumes are either dynamic or static. Both subclasses are measured at different degrees of inspiration or expiration; however, dynamic lung volumes are characteristically dependent on the rate of air flow. The static lung volumes/capacities are further subdivided into four standard volumes (tidal, inspiratory reserve, expiratory reserve, and residual volumes) and four standard capacities (inspiratory, functional residual, vital and total lung capacities). The dynamic lung volumes are mostly derived from vital capacity. While dynamic lung volumes are essential for diagnosis and follow up of obstructive lung diseases, static lung volumes are equally important for evaluation of obstructive as well as restrictive ventilatory defects. This review intends to update the reader with the physiological basis, clinical significance and interpretative approaches of the standard static lung volumes and capacities.

Cr3+ and Nb5+ co-doped Ti2Nb10O29 materials for high-performance lithium-ion storage

NASA Astrophysics Data System (ADS)

Yang, Chao; Yu, Shu; Ma, Yu; Lin, Chunfu; Xu, Zhihao; Zhao, Hua; Wu, Shunqing; Zheng, Peng; Zhu, Zi-Zhong; Li, Jianbao; Wang, Ning

2017-08-01

Ti2Nb10O29 is an advanced anode material for lithium-ion batteries due to its large specific capacity and high safety. However, its poor electronic/ionic conductivity significantly limits its rate capability. To tackle this issue, a Cr3+-Nb5+ co-doping is employed, and a series of CrxTi2-2xNb10+xO29 compounds are prepared. The co-doping does not change the Wadsley-Roth shear structure but increases the unit-cell volume and decreases the particle size. Due to the increased unit-cell volumes, the co-doped samples show increased Li+-ion diffusion coefficients. Experimental data and first-principle calculations reveal significantly increased electronic conductivities arising from the formation of impurity bands after the co-doping. The improvements of the electronic/ionic conductivities and the smaller particle sizes in the co-doped samples significantly contribute to improving their electrochemical properties. During the first cycle at 0.1 C, the optimized Cr0.6Ti0.8Nb10.6O29 sample delivers a large reversible capacity of 322 mAh g-1 with a large first-cycle Coulombic efficiency of 94.7%. At 10 C, it retains a large capacity of 206 mAh g-1, while that of Ti2Nb10O29 is only 80 mAh g-1. Furthermore, Cr0.6Ti0.8Nb10.6O29 shows high cyclic stability as demonstrated in over 500 cycles at 10 C with tiny capacity loss of only 0.01% per cycle.

Excess Diffuse Light Absorption in Upper Mesophyll Limits CO2 Drawdown and Depresses Photosynthesis1[OPEN

PubMed Central

Gilbert, Matthew E.; McElrone, Andrew J.

2017-01-01

In agricultural and natural systems, diffuse light can enhance plant primary productivity due to deeper penetration into and greater irradiance of the entire canopy. However, for individual sun-grown leaves from three species, photosynthesis is actually less efficient under diffuse compared with direct light. Despite its potential impact on canopy-level productivity, the mechanism for this leaf-level diffuse light photosynthetic depression effect is unknown. Here, we investigate if the spatial distribution of light absorption relative to electron transport capacity in sun- and shade-grown sunflower (Helianthus annuus) leaves underlies its previously observed diffuse light photosynthetic depression. Using a new one-dimensional porous medium finite element gas-exchange model parameterized with light absorption profiles, we found that weaker penetration of diffuse versus direct light into the mesophyll of sun-grown sunflower leaves led to a more heterogenous saturation of electron transport capacity and lowered its CO2 concentration drawdown capacity in the intercellular airspace and chloroplast stroma. This decoupling of light availability from photosynthetic capacity under diffuse light is sufficient to generate an 11% decline in photosynthesis in sun-grown but not shade-grown leaves, primarily because thin shade-grown leaves similarly distribute diffuse and direct light throughout the mesophyll. Finally, we illustrate how diffuse light photosynthetic depression could overcome enhancement in canopies with low light extinction coefficients and/or leaf area, pointing toward a novel direction for future research. PMID:28432257

Excess Diffuse Light Absorption in Upper Mesophyll Limits CO2 Drawdown and Depresses Photosynthesis.

PubMed

Earles, J Mason; Théroux-Rancourt, Guillaume; Gilbert, Matthew E; McElrone, Andrew J; Brodersen, Craig R

2017-06-01

In agricultural and natural systems, diffuse light can enhance plant primary productivity due to deeper penetration into and greater irradiance of the entire canopy. However, for individual sun-grown leaves from three species, photosynthesis is actually less efficient under diffuse compared with direct light. Despite its potential impact on canopy-level productivity, the mechanism for this leaf-level diffuse light photosynthetic depression effect is unknown. Here, we investigate if the spatial distribution of light absorption relative to electron transport capacity in sun- and shade-grown sunflower ( Helianthus annuus ) leaves underlies its previously observed diffuse light photosynthetic depression. Using a new one-dimensional porous medium finite element gas-exchange model parameterized with light absorption profiles, we found that weaker penetration of diffuse versus direct light into the mesophyll of sun-grown sunflower leaves led to a more heterogenous saturation of electron transport capacity and lowered its CO 2 concentration drawdown capacity in the intercellular airspace and chloroplast stroma. This decoupling of light availability from photosynthetic capacity under diffuse light is sufficient to generate an 11% decline in photosynthesis in sun-grown but not shade-grown leaves, primarily because thin shade-grown leaves similarly distribute diffuse and direct light throughout the mesophyll. Finally, we illustrate how diffuse light photosynthetic depression could overcome enhancement in canopies with low light extinction coefficients and/or leaf area, pointing toward a novel direction for future research. © 2017 American Society of Plant Biologists. All Rights Reserved.

Simulation of Amorphous Silicon Anode in Lithium-Ion Batteries

NASA Astrophysics Data System (ADS)

Wang, Miao

The energy density of the current generation of Li-ion batteries (LIBs) is only about 1% of that of gasoline. Improving the energy density of the rechargeable battery is critical for vehicle electrification. Employing high capacity electrode materials is a key factor in this endeavor. Silicon (Si) is one of the high capacity anode materials for LIBs. However, Si experiences large volume variation (up to 300%) during battery cycling, which affects the structural integrity of the battery and results in rapid capacity fading. It has been shown that the cycle life of Si anode can be improved significantly through various novel electrode designs. So far, such work is conducted through experiments. Numerical simulations have the potentials for design optimization of LIBs, as demonstrated in multiphysics models for LIBs with graphite anode. This research extends a previously developed microstructure-resolved multiphysics (MRM) battery model to LIBs with a-Si anode. The MRM model considers the electrochemical reactions, Li transport in electrodes and electrolyte, Li insertion induced volume change, mechanical strains and stresses, material property evolution with lithiation, and the chemo-mechanical coupling. The model is solved using finite element package COMSOL Multiphysics. The major challenges in this work are the large deformation of the Si, and the uncertainty in parameters and the coupling relation. To simulate the large deformation of Si, a large strain based formulation for the concentration induced volume expansion was used. The electrolyte was modeled as fluid. A method to simulate the galvanostatic charge/discharge of a finite deformation electrode with moving boundary was developed. Important model parameters were determined one by one by correlating the simulation to appropriate experiments. For example, the Li diffusivity in Si reported in literature varies from 10-13 to 10-19 m2/s. To estimate this parameter, the experiment of two-phase lithiation of a-Si nanospheres in-situ in a transmission electron microscope was simulated. The diffusivity was found at the order of 10-17m2/s for the lithium poor phase in first lithiation and 10-15m2/s for lithium rich phase and in subsequent cycles. The reaction rate constant and the apparent transfer coefficient are determined in a similar way using different experiments. In literature, different forms of chemo-mechanical coupling theories have been proposed for Li diffusion in Si. The coupling relationship and parameters were often derived based on one type of experiment even though the process is highly coupled. In this work, the chemo-mechanical coupling was investigated by simulations of two geometries: a thin film and a sphere. A strong asymmetric rate behavior between lithiation and delithiation has been observed in thin film a-Si anode but not in other geometries. The results reveal that the rate behavior is affected by the geometry and the constraint of the electrode, the chemo-mechanical coupling, and the prior process. A substrate-constrained film has a relatively low surface/volume ratio and a constant surface area. Its lithiation has a great tendency to be hindered by surface limitation. The chemo-mechanical coupling plays an important role in the specific rate behavior of a geometry. Finally, an MRM model was built for a half cell with a-Si nanowalls as anode. The specific and volumetric capacities of the cell as a function of size, length/size ratio, spacing of the nanostructure, and the Li+ concentration in electrolyte were investigated. The results show that the factors reducing the concentration polarization can enhance the maximum achievable SOC of the cell. However, the cell with the highest SOC does not necessarily lead to the highest capacity.

Estimation of gas and tissue lung volumes by MRI: functional approach of lung imaging.

PubMed

Qanadli, S D; Orvoen-Frija, E; Lacombe, P; Di Paola, R; Bittoun, J; Frija, G

1999-01-01

The purpose of this work was to assess the accuracy of MRI for the determination of lung gas and tissue volumes. Fifteen healthy subjects underwent MRI of the thorax and pulmonary function tests [vital capacity (VC) and total lung capacity (TLC)] in the supine position. MR examinations were performed at inspiration and expiration. Lung volumes were measured by a previously validated technique on phantoms. Both individual and total lung volumes and capacities were calculated. MRI total vital capacity (VC(MRI)) was compared with spirometric vital capacity (VC(SP)). Capacities were correlated to lung volumes. Tissue volume (V(T)) was estimated as the difference between the total lung volume at full inspiration and the TLC. No significant difference was seen between VC(MRI) and VC(SP). Individual capacities were well correlated (r = 0.9) to static volume at full inspiration. The V(T) was estimated to be 836+/-393 ml. This preliminary study demonstrates that MRI can accurately estimate lung gas and tissue volumes. The proposed approach appears well suited for functional imaging of the lung.

Effects of obesity on lung volume and capacity in children and adolescents: a systematic review

PubMed Central

Winck, Aline Dill; Heinzmann-Filho, João Paulo; Soares, Rafaela Borges; da Silva, Juliana Severo; Woszezenki, Cristhiele Taís; Zanatta, Letiane Bueno

2016-01-01

Abstract Objective: To assess the effects of obesity on lung volume and capacity in children and adolescents. Data source: This is a systematic review, carried out in Pubmed, Lilacs, Scielo and PEDro databases, using the following Keywords: Plethysmography; Whole Body OR Lung Volume Measurements OR Total Lung Capacity OR Functional Residual Capacity OR Residual Volume AND Obesity. Observational studies or clinical trials that assessed the effects of obesity on lung volume and capacity in children and adolescents (0-18 years) without any other associated disease; in English; Portuguese and Spanish languages were selected. Methodological quality was assessed by the Agency for Healthcare Research and Quality. Data synthesis: Of the 1,030 articles, only four were included in the review. The studies amounted to 548 participants, predominantly males, with sample size ranging from 45 to 327 individuals. 100% of the studies evaluated nutritional status through BMI (z-score) and 50.0% reported the data on abdominal circumference. All demonstrated that obesity causes negative effects on lung volume and capacity, causing a reduction mainly in functional residual capacity in 75.0% of the studies; in the expiratory reserve volume in 50.0% and in the residual volume in 25.0%. The methodological quality ranged from moderate to high, with 75.0% of the studies classified as having high methodological quality. Conclusions: Obesity causes deleterious effects on lung volume and capacity in children and adolescents, mainly by reducing functional residual capacity, expiratory reserve volume and residual volume. PMID:27130483

Short-term Automated Quantification of Radiologic Changes in the Characterization of Idiopathic Pulmonary Fibrosis Versus Nonspecific Interstitial Pneumonia and Prediction of Long-term Survival.

PubMed

De Giacomi, Federica; Raghunath, Sushravya; Karwoski, Ronald; Bartholmai, Brian J; Moua, Teng

2018-03-01

Fibrotic interstitial lung diseases presenting with nonspecific and overlapping radiologic findings may be difficult to diagnose without surgical biopsy. We hypothesized that baseline quantifiable radiologic features and their short-term interval change may be predictive of underlying histologic diagnosis as well as long-term survival in idiopathic pulmonary fibrosis (IPF) presenting without honeycombing versus nonspecific interstitial pneumonia (NSIP). Forty biopsy-confirmed IPF and 20 biopsy-confirmed NSIP patients with available high-resolution chest computed tomography 4 to 24 months apart were studied. CALIPER software was used for the automated characterization and quantification of radiologic findings. IPF subjects were older (66 vs. 48; P<0.0001) with lower diffusion capacity for carbon monoxide and higher volumes of baseline reticulation (193 vs. 83 mL; P<0.0001). Over the interval period, compared with NSIP, IPF patients experienced greater functional decline (forced vital capacity, -6.3% vs. -1.7%; P=0.02) and radiologic progression, as noted by greater increase in reticulation volume (24 vs. 1.74 mL; P=0.048), and decrease in normal (-220 vs. -37.7 mL; P=0.045) and total lung volumes (-198 vs. 58.1 mL; P=0.03). Older age, male gender, higher reticulation volumes at baseline, and greater interval decrease in normal lung volumes were predictive of IPF. Both baseline and short-term changes in quantitative radiologic findings were predictive of mortality. Baseline quantitative radiologic findings and assessment of short-term disease progression may help characterize underlying IPF versus NSIP in those with difficult to differentiate clinicoradiologic presentations. Our study supports the possible utility of assessing serial quantifiable high-resolution chest computed tomographic findings for disease differentiation in these 2 entities.

Effects of an individual 12-week community-located "start-to-run" program on physical capacity, walking, fatigue, cognitive function, brain volumes, and structures in persons with multiple sclerosis.

PubMed

Feys, Peter; Moumdjian, Lousin; Van Halewyck, Florian; Wens, Inez; Eijnde, Bert O; Van Wijmeersch, Bart; Popescu, Veronica; Van Asch, Paul

2017-11-01

Exercise therapy studies in persons with multiple sclerosis (pwMS) primarily focused on motor outcomes in mid disease stage, while cognitive function and neural correlates were only limitedly addressed. This pragmatic randomized controlled study investigated the effects of a remotely supervised community-located "start-to-run" program on physical and cognitive function, fatigue, quality of life, brain volume, and connectivity. In all, 42 pwMS were randomized to either experimental (EXP) or waiting list control (WLC) group. The EXP group received individualized training instructions during 12 weeks (3×/week), to be performed in their community aiming to participate in a running event. Measures were physical (VO 2max , sit-to-stand test, Six-Minute Walk Test (6MWT), Multiple Sclerosis Walking Scale-12 (MSWS-12)) and cognitive function (Rao's Brief Repeatable Battery (BRB), Paced Auditory Serial Attention Test (PASAT)), fatigue (Fatigue Scale for Motor and Cognitive Function (FSMC)), quality of life (Multiple Sclerosis Impact Scale-29 (MSIS-29)), and imaging. Brain volumes and diffusion tensor imaging (DTI) were quantified using FSL-SIENA/FIRST and FSL-TBSS. In all, 35 pwMS completed the trial. Interaction effects in favor of the EXP group were found for VO 2max , sit-to-stand test, MSWS-12, Spatial Recall Test, FSMC, MSIS-29, and pallidum volume. VO 2max improved by 1.5 mL/kg/min, MSWS-12 by 4, FSMC by 11, and MSIS-29 by 14 points. The Spatial Recall Test improved by more than 10%. Community-located run training improved aerobic capacity, functional mobility, visuospatial memory, fatigue, and quality of life and pallidum volume in pwMS.

Exfoliated-SnS2 restacked on graphene as a high-capacity, high-rate, and long-cycle life anode for sodium ion batteries

NASA Astrophysics Data System (ADS)

Liu, Yongchang; Kang, Hongyan; Jiao, Lifang; Chen, Chengcheng; Cao, Kangzhe; Wang, Yijing; Yuan, Huatang

2015-01-01

Designed as a high-capacity, high-rate, and long-cycle life anode for sodium ion batteries, exfoliated-SnS2 restacked on graphene is prepared by the hydrolysis of lithiated SnS2 followed by a facile hydrothermal method. Structural and morphological characterizations demonstrate that ultrasmall SnS2 nanoplates (with a typical size of 20-50 nm) composed of 2-5 layers are homogeneously decorated on the surface of graphene, while the hybrid structure self-assembles into a three-dimensional (3D) network architecture. The obtained SnS2/graphene nanocomposite delivers a remarkable capacity as high as 650 mA h g-1 at a current density of 200 mA g-1. More impressively, the capacity can reach 326 mA h g-1 even at 4000 mA g-1 and remains stable at ~610 mA h g-1 without fading up to 300 cycles when the rate is brought back to 200 mA g-1. The excellent electrochemical performance is attributed to the synergetic effects between the ultrasmall SnS2 and the highly conductive graphene network. The unique structure can simultaneously facilitate Na+ ion diffusion, provide more reaction sites, and suppress aggregation and volume fluctuation of the active materials during prolonged cycling.Designed as a high-capacity, high-rate, and long-cycle life anode for sodium ion batteries, exfoliated-SnS2 restacked on graphene is prepared by the hydrolysis of lithiated SnS2 followed by a facile hydrothermal method. Structural and morphological characterizations demonstrate that ultrasmall SnS2 nanoplates (with a typical size of 20-50 nm) composed of 2-5 layers are homogeneously decorated on the surface of graphene, while the hybrid structure self-assembles into a three-dimensional (3D) network architecture. The obtained SnS2/graphene nanocomposite delivers a remarkable capacity as high as 650 mA h g-1 at a current density of 200 mA g-1. More impressively, the capacity can reach 326 mA h g-1 even at 4000 mA g-1 and remains stable at ~610 mA h g-1 without fading up to 300 cycles when the rate is brought back to 200 mA g-1. The excellent electrochemical performance is attributed to the synergetic effects between the ultrasmall SnS2 and the highly conductive graphene network. The unique structure can simultaneously facilitate Na+ ion diffusion, provide more reaction sites, and suppress aggregation and volume fluctuation of the active materials during prolonged cycling. Electronic supplementary information (ESI) available: Scheme S1, Fig. S1-S4. See DOI: 10.1039/c4nr05106h

Abnormal pulmonary function and respiratory muscle strength findings in Chinese patients with Parkinson's disease and multiple system atrophy--comparison with normal elderly.

PubMed

Wang, Yao; Shao, Wei-bo; Gao, Li; Lu, Jie; Gu, Hao; Sun, Li-hua; Tan, Yan; Zhang, Ying-dong

2014-01-01

There have been limited comparative data regarding the investigations on pulmonary and respiratory muscle function in the patients with different parkinsonism disorders such as Parkinson's disease (PD) and multiple system atrophy (MSA) versus normal elderly. The present study is aiming to characterize the performance of pulmonary function and respiratory muscle strength in PD and MSA, and to investigate the association with severity of motor symptoms and disease duration. Pulmonary function and respiratory muscle strength tests were performed in 30 patients with PD, 27 with MSA as well as in 20 age-, sex-, height-, weight-matched normal elderly controls. All the patients underwent United Parkinson's disease rating scale (UPDRS) or united multiple system atrophy rating scale (UMSARS) separately as diagnosed. Vital capacity, forced expiratory volume in 1 second and forced vital capacity decreased, residual volume and ratio of residual volume to total lung capacity increased in both PD and MSA groups compared to controls (p<0.05). Diffusing capacity was decreased in the MSA group, compared with PD and normal elderly control groups (p<0.05). Respiratory muscle strength was lower in both PD and MSA groups than in controls (p<0.05). The values representing spirometry function and respiratory muscle strength were found to have a negative linear correlation with mean score of UPDRS-III in PD and mean score of UMSARS-I in MSA. Respiratory muscle strength showed a negative linear correlation with the mean score of UMSARS-II and disease duration in MSA patients. These findings suggest that respiratory dysfunction is involved in PD and MSA. Respiratory muscle strength is remarkably reduced, and some of the parameters correlate with disease duration and illness severity. The compromised respiratory function in neurodegenerative disorders should be the focus of further researches.

Use of body plethysmography to measure effect of bimaxillary orthognathic surgery on airway resistance and lung volumes.

PubMed

Rezaeetalab, Fariba; Kazemian, Mozhgan; Vaezi, Touraj; Shaban, Barratollah

2015-12-01

Bimaxillary orthognathic surgery can cause changes to respiration and the airways. We used body plethysmography to evaluate its effect on airway resistance and lung volumes in 20 patients with class III malocclusions (8 men and 12 women, aged 17 - 32 years). Lung volumes (forced vital capacity; forced inspiratory volume/one second; forced expiratory volume/one second: forced vital capacity; peak expiratory flow; maximum expiratory flow 25-75; maximum inspiratory flow; total lung capacity; residual volume; residual volume:total lung capacity), and airway resistance were evaluated one week before, and six months after, operation. Bimaxillary operations to correct class III malocclusions significantly increased airway resistance, residual volume, total lung capacity, and residual volume:total lung capacity. Other variables also changed after operation but not significantly so. Orthognathic operations should be done with caution in patients who have pre-existing respiratory diseases. Copyright © 2015 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Based on Cu as framework constructed nanoporous CuO/Cu composites by a dealloy method for sodium-ion battery anode

NASA Astrophysics Data System (ADS)

Zheng, Tian; Li, Guangda; Li, Deming; Meng, Xiangeng

2018-05-01

Nanoporous CuO/Cu composites with a continuous channel structure were fabricated through a corroding Cu-Al alloy process. The width of the continuous channels was about 20 50 nm. Nanoporous structure could effectively sustain the volume expansion during the Na+ insertion/extraction process and shorten the Na+ diffusion length as well, which thus helps improve the Na+ storage performance. Moreover, the nanoporous structure can improve the contact area between the electrolyte and the electrode, leading to an increment in the number of Na+ insertion/extraction sites. When used as the anode for sodium-ion batteries, the CuO/Cu exhibited an initial capacity of 580 mAh g-1, and the capacity is maintained at 200 mAh g-1 after 200 cycles at a current density of 500 mA g-1.

Computerized tomography and pulmonary diffusing capacity in highly trained athletes after performing a triathlon.

PubMed

Caillaud, C; Serre-Cousiné, O; Anselme, F; Capdevilla, X; Préfaut, C

1995-10-01

We investigated the computerized tomographies (CTs) of the thorax and the pulmonary diffusing capacity for CO (DLCO) in eight male athletes before and after a triathlon. DLCO and alveolar volume (VA) were simultaneously measured during 9 s of breath holding. The transfer coefficient (KCO = DLCO/VA) was then calculated. CT scanning was performed during breath holding with the subjects in the supine position. Scanner analysis was done by 1) counting the linear and polygonal opacities (index of interstitial fluid accumulation) and 2) calculating the physical mean lung density and the mean slice mass. Results showed a significant reduction in DLCO (44.9 +/- 2.3 vs. 42.9 +/- 1.7 ml.min-1.mmHg-1; P < 0.05) and KCO (6.0 +/- 0.3 vs. 5.6 +/- 0.3 ml.min-1.mmHg-1.l of VA-1; P < 0.05) after the triathlon and an increase in mean lung density (0.21 +/- 0.009 vs. 0.25 +/- 0.01 g/cm3; P < 0.0001). The number of polygonal and linear opacities increased after the race (P < 0.001). This study confirmed that DLCO and KCO decrease in elite athletes after a long-distance race and showed a concomitant increase in CT lung density and in the number of opacities.

Recommendations for a Standardized Pulmonary Function Report. An Official American Thoracic Society Technical Statement.

PubMed

Culver, Bruce H; Graham, Brian L; Coates, Allan L; Wanger, Jack; Berry, Cristine E; Clarke, Patricia K; Hallstrand, Teal S; Hankinson, John L; Kaminsky, David A; MacIntyre, Neil R; McCormack, Meredith C; Rosenfeld, Margaret; Stanojevic, Sanja; Weiner, Daniel J

2017-12-01

The American Thoracic Society committee on Proficiency Standards for Pulmonary Function Laboratories has recognized the need for a standardized reporting format for pulmonary function tests. Although prior documents have offered guidance on the reporting of test data, there is considerable variability in how these results are presented to end users, leading to potential confusion and miscommunication. A project task force, consisting of the committee as a whole, was approved to develop a new Technical Standard on reporting pulmonary function test results. Three working groups addressed the presentation format, the reference data supporting interpretation of results, and a system for grading quality of test efforts. Each group reviewed relevant literature and wrote drafts that were merged into the final document. This document presents a reporting format in test-specific units for spirometry, lung volumes, and diffusing capacity that can be assembled into a report appropriate for a laboratory's practice. Recommended reference sources are updated with data for spirometry and diffusing capacity published since prior documents. A grading system is presented to encourage uniformity in the important function of test quality assessment. The committee believes that wide adoption of these formats and their underlying principles by equipment manufacturers and pulmonary function laboratories can improve the interpretation, communication, and understanding of test results.

Putaminal volume and diffusion in early familial Creutzfeldt-Jakob disease.

PubMed

Seror, Ilana; Lee, Hedok; Cohen, Oren S; Hoffmann, Chen; Prohovnik, Isak

2010-01-15

The putamen is centrally implicated in the pathophysiology of Creutzfeldt-Jakob Disease (CJD). To our knowledge, its volume has never been measured in this disease. We investigated whether gross putaminal atrophy can be detected by MRI in early stages, when the diffusion is already reduced. Twelve familial CJD patients with the E200K mutation and 22 healthy controls underwent structural and diffusion MRI scans. The putamen was identified in anatomical scans by two methods: manual tracing by a blinded investigator, and automatic parcellation by a computerized segmentation procedure (FSL FIRST). For each method, volume and mean Apparent Diffusion Coefficient (ADC) were calculated. ADC was significantly lower in CJD patients (697+/-64 microm(2)/s vs. 750+/-31 microm(2)/s, p<0.005), as expected, but the volume was not reduced. The computerized FIRST delineation yielded comparable ADC values to the manual method, but computerized volumes were smaller than manual tracing values. We conclude that significant diffusion reduction in the putamen can be detected by delineating the structure manually or with a computerized algorithm. Our findings confirm and extend previous voxel-based and observational studies. Putaminal volume was not reduced in our early-stage patients, thus confirming that diffusion abnormalities precede detectible atrophy in this structure.

What Is the Optimal Target Convective Volume in On-Line Hemodiafiltration Therapy?

PubMed

Canaud, Bernard; Koehler, Katrin; Bowry, Sudhir; Stuard, Stefano

2017-01-01

Conventional diffusion-based dialysis modalities including high-flux hemodialysis are limited in their capacity to effectively remove large uremic toxins and to improve outcomes for end-stage chronic kidney disease (ESKD) patients. By increasing convective solute transport, hemodiafiltration (HDF) enhances solute removal capacity over a broad range of middle- and large-size uremic toxins implicated in the pathophysiology of chronic kidney disease. Furthermore, by offering flexible convection volume, on-line HDF permits customizing the treatment dose to the patient's needs. In addition, convective-based modalities have been shown to improve hemodynamic stability and to reduce patients' inflammation profile - both of which are implicated in CKD morbidity and mortality. Growing clinical evidence indicates that HDF-based modalities provide ESKD patients with a number of clinical and biological benefits, including improved outcomes. Interestingly, it has recently emerged that the clinical benefits associated with HDF are positively associated with the total ultrafiltered volume per session (and per week), namely convective dose. In this chapter, we revisit the concept of convective dose and discuss the threshold value above which an improvement in ESKD patient outcome can be expected. This particular point will be addressed by stratifying the level of efficacy of convective volumes, schematically defined as minimal, optimal, personalized, and maximal. In addition, factors and best clinical practices implicated in the achievement of an optimal convective dose are reviewed. To conclude, we show how HDF differs from standard hemodialysis and why HDF offers a paradigm shift in renal replacement therapy. © 2017 S. Karger AG, Basel.

Sulfur nanocrystals confined in carbon nanotube network as a binder-free electrode for high-performance lithium sulfur batteries.

PubMed

Sun, Li; Li, Mengya; Jiang, Ying; Kong, Weibang; Jiang, Kaili; Wang, Jiaping; Fan, Shoushan

2014-07-09

A binder-free nano sulfur-carbon nanotube composite material featured by clusters of sulfur nanocrystals anchored across the superaligned carbon nanotube (SACNT) matrix is fabricated via a facile solution-based method. The conductive SACNT matrix not only avoids self-aggregation and ensures dispersive distribution of the sulfur nanocrystals but also offers three-dimensional continuous electron pathway, provides sufficient porosity in the matrix to benefit electrolyte infiltration, confines the sulfur/polysulfides, and accommodates the volume variations of sulfur during cycling. The nanosized sulfur particles shorten lithium ion diffusion path, and the confinement of sulfur particles in the SACNT network guarantees the stability of structure and electrochemical performance of the composite. The nano S-SACNT composite cathode delivers an initial discharge capacity of 1071 mAh g(-1), a peak capacity of 1088 mAh g(-1), and capacity retention of 85% after 100 cycles with high Coulombic efficiency (∼100%) at 1 C. Moreover, at high current rates the nano S-SACNT composite displays impressive capacities of 1006 mAh g(-1) at 2 C, 960 mAh g(-1) at 5 C, and 879 mAh g(-1) at 10 C.

Scalable synthesis of NiMoO4 microspheres with numerous empty nanovoids as an advanced anode material for Li-ion batteries

NASA Astrophysics Data System (ADS)

Park, Jin-Sung; Cho, Jung Sang; Kang, Yun Chan

2018-03-01

Closely in line with advances in next-generation energy storage materials, anode materials for lithium-ion batteries (LIBs) with high capacity and long cycle life have been widely explored. As part of the current effort, nickel molybdate (NiMoO4) microspheres with empty nanovoids are synthesized via spray drying process and subsequent one-step calcination in air. Dextrin in the atomized droplet is phase segregated during the spray drying process and calcined in air atmosphere, resulting in numerous empty nanovoids well-distributed within a microsphere. The empty nanovoids alleviate volume expansion during cycling, shorten lithium-ion diffusion length, and facilitate contact between electrode and electrolyte materials. Along with the high discharge capacity of NiMoO4 material, as high as 1240 mA h g-1 for the 2nd cycle at a high current density of 1 A g-1, uniquity of the structure enables longer cycle life and higher quality performances. The discharge capacity corresponding to the 500th cycle is 1020 mA h g-1 and the capacity retention calculated from the 2nd cycle is 82%. In addition, a discharge capacity of 413 mA g-1 is obtained at an extremely high current density of 10 A g-1.

Tellurium-Impregnated Porous Cobalt-Doped Carbon Polyhedra as Superior Cathodes for Lithium-Tellurium Batteries.

PubMed

He, Jiarui; Lv, Weiqiang; Chen, Yuanfu; Wen, Kechun; Xu, Chen; Zhang, Wanli; Li, Yanrong; Qin, Wu; He, Weidong

2017-08-22

Lithium-tellurium (Li-Te) batteries are attractive for energy storage owing to their high theoretical volumetric capacity of 2621 mAh cm -3 . In this work, highly nanoporous cobalt and nitrogen codoped carbon polyhedra (C-Co-N) derived from a metal-organic framework (MOF) is synthesized and employed as tellurium host for Li-Te batteries. The Te@C-Co-N cathode with a high Te loading of 77.2 wt % exhibits record-breaking electrochemical performances including an ultrahigh initial capacity of 2615.2 mAh cm -3 approaching the theoretical capacity of Te (2621 mAh cm -3 ), a superior cycling stability with a high capacity retention of 93.6%, a ∼99% Columbic efficiency after 800 cycles as well as rate capacities of 2160, 1327.6, and 894.8 mAh cm -3 at 4, 10, and 20 C, respectively. The redox chemistry of tellurium is revealed by in operando Raman spectroscopic analysis and density functional theory simulations. The results illustrate that the performances are attributed to the highly conductive C-Co-N matrix with an advantageous structure of abundant micropores, which provides highly efficient channels for electron transfer and ionic diffusion as well as sufficient surface area to efficiently host tellurium while mitigating polytelluride dissolution and suppressing volume expansion.

Quantification of lung microstructure with hyperpolarized 3He diffusion MRI

PubMed Central

Sukstanskii, Alexander L.; Woods, Jason C.; Gierada, David S.; Quirk, James D.; Hogg, James C.; Cooper, Joel D.; Conradi, Mark S.

2009-01-01

The structure and integrity of pulmonary acinar airways and their changes in different diseases are of great importance and interest to a broad range of physiologists and clinicians. The introduction of hyperpolarized gases has opened a door to in vivo studies of lungs with MRI. In this study we demonstrate that MRI-based measurements of hyperpolarized 3He diffusivity in human lungs yield quantitative information on the value and spatial distribution of lung parenchyma surface-to-volume ratio, number of alveoli per unit lung volume, mean linear intercept, and acinar airway radii—parameters that have been used by lung physiologists for decades and are accepted as gold standards for quantifying emphysema. We validated our MRI-based method in six human lung specimens with different levels of emphysema against direct unbiased stereological measurements. We demonstrate for the first time MRI images of these lung microgeometric parameters in healthy lungs and lungs with different levels of emphysema (mild, moderate, and severe). Our data suggest that decreases in lung surface area per volume at the initial stages of emphysema are due to dramatic decreases in the depth of the alveolar sleeves covering the alveolar ducts and sacs, implying dramatic decreases in the lung's gas exchange capacity. Our novel methods are sufficiently sensitive to allow early detection and diagnosis of emphysema, providing an opportunity to improve patient treatment outcomes, and have the potential to provide safe and noninvasive in vivo biomarkers for monitoring drug efficacy in clinical trials. PMID:19661452

Respiratory health of workers exposed to low levels of chromium in stainless steel production.

PubMed Central

Huvinen, M; Uitti, J; Zitting, A; Roto, P; Virkola, K; Kuikka, P; Laippala, P; Aitio, A

1996-01-01

OBJECTIVES: To determine whether occupational exposure to chromite, trivalent chromium, or hexavalent chromium causes respiratory diseases, an excess of respiratory symptoms, a decrease in pulmonary function, or signs of pneumoconiosis among workers in an integrated chain of stainless steel production. METHODS: This cross sectional study was carried out in 1993 and the inclusion criterion was a minimum of eight years of employment in the same production department. A self administered questionnaire was collected, and spirometry, measurement of diffusing capacity, chest radiography, and laboratory tests were carried out by a mobile research unit. RESULTS: There were 221 workers in the exposure groups and 95 in the control group. The average duration of employment was 18 years. No significant differences in the odds ratios (ORs) of the symptoms were found between the exposure and the control groups. In a logistic regression analysis age and smoking significantly explained the occurrence of most of the respiratory symptoms. The smokers in the chromite group had significantly lower forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and diffusing capacity than the corresponding values of the control group. The analysis of variance between study groups, smoking, and exposure time, without modelling for interactions, showed that the chromite group had lower values for FVC, FEV1, and diffusing capacity than the other groups. The occurrence of small opacities was more frequent on the chest radiographs of the workers in the chromite group. CONCLUSIONS: An average exposure time of 18 years in ferrochromium and stainless steel production and exposure to dusts containing low concentrations of hexavalent or trivalent chromium do not lead to any respiratory changes detectable by lung function tests or radiography nor to any increase in symptoms of respiratory diseases. The lung function values were lower and the occurrence of radiological findings was more frequent among the workers from the chromite mine than among the controls. The difference was partly caused by differences in age and smoking habits, but evidently also partly by higher exposures more than two decades ago or by the fibrous components of the dust. PMID:9038797

Modeling of molecular diffusion and thermal conduction with multi-particle interaction in compressible turbulence

NASA Astrophysics Data System (ADS)

Tai, Y.; Watanabe, T.; Nagata, K.

2018-03-01

A mixing volume model (MVM) originally proposed for molecular diffusion in incompressible flows is extended as a model for molecular diffusion and thermal conduction in compressible turbulence. The model, established for implementation in Lagrangian simulations, is based on the interactions among spatially distributed notional particles within a finite volume. The MVM is tested with the direct numerical simulation of compressible planar jets with the jet Mach number ranging from 0.6 to 2.6. The MVM well predicts molecular diffusion and thermal conduction for a wide range of the size of mixing volume and the number of mixing particles. In the transitional region of the jet, where the scalar field exhibits a sharp jump at the edge of the shear layer, a smaller mixing volume is required for an accurate prediction of mean effects of molecular diffusion. The mixing time scale in the model is defined as the time scale of diffusive effects at a length scale of the mixing volume. The mixing time scale is well correlated for passive scalar and temperature. Probability density functions of the mixing time scale are similar for molecular diffusion and thermal conduction when the mixing volume is larger than a dissipative scale because the mixing time scale at small scales is easily affected by different distributions of intermittent small-scale structures between passive scalar and temperature. The MVM with an assumption of equal mixing time scales for molecular diffusion and thermal conduction is useful in the modeling of the thermal conduction when the modeling of the dissipation rate of temperature fluctuations is difficult.

Calibration of High Temperature Thermal Conductivity System: New Algorithm to Measure Heat Capacity Using Flash Thermal Diffusivity in Thermoelectric Materials

NASA Technical Reports Server (NTRS)

Deb, Rahul; Snyder, Jeff G.

2005-01-01

A viewgraph presentation describing thermoelectric materials, an algorithm for heat capacity measurements and the process of flash thermal diffusivity. The contents include: 1) What are Thermoelectrics?; 2) Thermoelectric Applications; 3) Improving Thermoelectrics; 4) Research Goal; 5) Flash Thermal Diffusivity; 6) Background Effects; 7) Stainless Steel Comparison; 8) Pulse Max Integral; and 9) Graphite Comparison Algorithm.

Effects of obesity on lung volume and capacity in children and adolescents: a systematic review.

PubMed

Winck, Aline Dill; Heinzmann-Filho, João Paulo; Soares, Rafaela Borges; da Silva, Juliana Severo; Woszezenki, Cristhiele Taís; Zanatta, Letiane Bueno

2016-12-01

To assess the effects of obesity on lung volume and capacity in children and adolescents. This is a systematic review, carried out in Pubmed, Lilacs, Scielo and PEDro databases, using the following Keywords: Plethysmography; Whole Body OR Lung Volume Measurements OR Total Lung Capacity OR Functional Residual Capacity OR Residual Volume AND Obesity. Observational studies or clinical trials that assessed the effects of obesity on lung volume and capacity in children and adolescents (0-18 years) without any other associated disease; in English; Portuguese and Spanish languages were selected. Methodological quality was assessed by the Agency for Healthcare Research and Quality. Of the 1,030 articles, only four were included in the review. The studies amounted to 548 participants, predominantly males, with sample size ranging from 45 to 327 individuals. 100% of the studies evaluated nutritional status through BMI (z-score) and 50.0% reported the data on abdominal circumference. All demonstrated that obesity causes negative effects on lung volume and capacity, causing a reduction mainly in functional residual capacity in 75.0% of the studies; in the expiratory reserve volume in 50.0% and in the residual volume in 25.0%. The methodological quality ranged from moderate to high, with 75.0% of the studies classified as having high methodological quality. Obesity causes deleterious effects on lung volume and capacity in children and adolescents, mainly by reducing functional residual capacity, expiratory reserve volume and residual volume. Copyright © 2016 Sociedade de Pediatria de São Paulo. Publicado por Elsevier Editora Ltda. All rights reserved.

A theoretical study of fluid forces on a centrifugal impeller rotating and whirling in a vaned diffuser

NASA Technical Reports Server (NTRS)

Tsujimoto, Yoshinobu; Acosta, Allan J.; Yoshida, Yoshiki

1989-01-01

The fluid forces on a centrifugal impeller rotating and whirling in a vaned diffuser are analyzed on the assumption that the number of impeller and diffuser vanes is so large that the flows are perfectly guided by the vanes. The flow is taken to be two dimensional, inviscid, and incompressible, but the effects of impeller and diffuser losses are taken into account. It is shown that the interaction with the vaned diffuser may cause destabilizing fluid forces. From these discussions, it is found that the whirling forces are closely related to the steady head-capacity characteristics of the impeller. This physical understanding of the whirling forces can be applied also to the cases with volute casings. At partial capacities, it is shown that the impeller forces change greatly when the flow rate and whirl velocity are near to the impeller or vaned diffuser attributed rotating stall onset capacity, and the stall propagation velocity, respectively. In such cases the impeller forces may become destabilizing for impeller whirl.

Thermal and ultrasonic evaluation of porosity in composite laminates

NASA Technical Reports Server (NTRS)

Johnston, Patrick H.; Winfree, William P.; Long, Edward R., Jr.; Kullerd, Susan M.; Nathan, N.; Partos, Richard D.

1992-01-01

The effects of porosity on damage incurred by low-velocity impact are investigated. Specimens of graphite/epoxy composite were fabricated with various volume fractions of voids. The void fraction was independently determined using optical examination and acid resin digestion methods. Thermal diffusivity and ultrasonic attenuation were measured, and these results were related to the void volume fraction. The relationship between diffusivity and fiber volume fraction was also considered. The slope of the ultrasonic attenuation coefficient was found to increase linearly with void content, and the diffusivity decreased linearly with void volume fraction, after compensation for an approximately linear dependence on the fiber volume fraction.

Reconciling transport models across scales: The role of volume exclusion

NASA Astrophysics Data System (ADS)

Taylor, P. R.; Yates, C. A.; Simpson, M. J.; Baker, R. E.

2015-10-01

Diffusive transport is a universal phenomenon, throughout both biological and physical sciences, and models of diffusion are routinely used to interrogate diffusion-driven processes. However, most models neglect to take into account the role of volume exclusion, which can significantly alter diffusive transport, particularly within biological systems where the diffusing particles might occupy a significant fraction of the available space. In this work we use a random walk approach to provide a means to reconcile models that incorporate crowding effects on different spatial scales. Our work demonstrates that coarse-grained models incorporating simplified descriptions of excluded volume can be used in many circumstances, but that care must be taken in pushing the coarse-graining process too far.

Measuring diffusion-relaxation correlation maps using non-uniform field gradients of single-sided NMR devices.

PubMed

Nogueira d'Eurydice, Marcel; Galvosas, Petrik

2014-11-01

Single-sided NMR systems are becoming a relevant tool in industry and laboratory environments due to their low cost, low maintenance and capacity to evaluate quantity and quality of hydrogen based materials. The performance of such devices has improved significantly over the last decade, providing increased field homogeneity, field strength and even controlled static field gradients. For a class of these devices, the configuration of the permanent magnets provides a linear variation of the magnetic field and can be used in diffusion measurements. However, magnet design depends directly on its application and, according to the purpose, the field homogeneity may significantly be compromised. This may prevent the determination of diffusion properties of fluids based on the natural inhomogeneity of the field using known techniques. This work introduces a new approach that extends the applicability of diffusion-editing CPMG experiments to NMR devices with highly inhomogeneous magnetic fields, which do not vary linearly in space. Herein, we propose a method to determine a custom diffusion kernel based on the gradient distribution, which can be seen as a signature of each NMR device. This new diffusion kernel is then utilised in the 2D inverse Laplace transform (2D ILT) in order to determine diffusion-relaxation correlation maps of homogeneous multi-phasic fluids. The experiments were performed using NMR MObile Lateral Explore (MOLE), which is a single-sided NMR device designed to maximise the volume at the sweet spot with enhanced depth penetration. Copyright © 2014 Elsevier Inc. All rights reserved.

Variation in lung volumes and capacities among young males in relation to height.

PubMed

Bhatti, Urooj; Rani, Keenjher; Memon, Muhammad Qasim

2014-01-01

Vital Capacity (VC) is defined as a change in volume of lung after maximal inspiration followed by maximal expiration is called Vital Capacity of lungs. It is the sum of tidal volume, inspiratory reserve volume .and expiratory reserve volume. Vital capacity of normal adults ranges between 3 to 5 litres. A number of physiological factors like age, gender, height and ethnicity effect lung volumes. The reference values of lung volume and capacities were calculated previously and those studies played pivotal role in establishing the fact that air volume capacities measured in an individual fall within a wide range among healthy persons of same age, gender and height buit with different ethnicity. The objective of this study was to evaluate the changes in vital capacity in with height and gender. This cross-sectional study included 74 male students in the Department of Physiology, Liaquat University of Medical and Health Sciences, Jamshoro during January-March, 2014. The volunteers were divided into 2 groups of height ≤ 167.4 cm and > 167.4 cm. The volunteers' height was measured in cm. Vital capacity of the subjects was measured using standard protocol. Mean ± SD of age, height and vital capacity were calculated. Mean vital capacity in students with height > 167.4 cm was higher than average vital capacity of students with height ≤ 167.4 cm. It might be due to the increased surface area of the lungs in relation with increasing height. There are variations in vital capacity of individuals in relation to their heights, within the same ethnic and age groups.

Thermal properties of U-7Mo/Al dispersion fuel

NASA Astrophysics Data System (ADS)

Cho, Tae Won; Kim, Yeon Soo; Park, Jong Man; Lee, Kyu Hong; Kim, Sunghwan; Lee, Chong-Tak; Yang, Jae Ho; Oh, Jang Soo; Won, Ju-Jin; Sohn, Dong-Seong

2017-12-01

The thermal diffusivity and heat capacity of U-7Mo/Al and U-7Mo/Al-5Si as functions of U-Mo fuel volume fraction and temperature were measured. The density of the sample was measured at room temperature and estimated using thermal expansion data at elevated temperatures. Using the measured data, the thermal conductivity was obtained as a function of U-Mo volume fraction and temperature. The thermal conductivity of U-7Mo/Al-5Si was found to be lower than that of U-7Mo/Al because of the Si addition to the Al. Due to a lower porosity and reduced interaction between U-Mo and Al in the sample, the thermal conductivity data reported in the present study were higher than those in the literature. The present data were found to be in agreement with the predictions of theoretical models.

Advanced Techniques in Pulmonary Function Test Analysis Interpretation and Diagnosis

PubMed Central

Gildea, T.J.; Bell, C. William

1980-01-01

The Pulmonary Functions Analysis and Diagnostic System is an advanced clinical processing system developed for use at the Pulmonary Division, Department of Medicine at the University of Nebraska Medical Center. The system generates comparative results and diagnostic impressions for a variety of routine and specialized pulmonary functions test data. Routine evaluation deals with static lung volumes, breathing mechanics, diffusing capacity, and blood gases while specialized tests include lung compliance studies, small airways dysfunction studies and dead space to tidal volume ratios. Output includes tabular results of normal vs. observed values, clinical impressions and commentary and, where indicated, a diagnostic impression. A number of pulmonary physiological and state variables are entered or sampled (A to D) with periodic status reports generated for the test supervisor. Among the various physiological variables sampled are respiratory frequency, minute ventilation, oxygen consumption, carbon dioxide production, and arterial oxygen saturation.

Self-diffusion in compressively strained Ge

NASA Astrophysics Data System (ADS)

Kawamura, Yoko; Uematsu, Masashi; Hoshi, Yusuke; Sawano, Kentarou; Myronov, Maksym; Shiraki, Yasuhiro; Haller, Eugene E.; Itoh, Kohei M.

2011-08-01

Under a compressive biaxial strain of ˜ 0.71%, Ge self-diffusion has been measured using an isotopically controlled Ge single-crystal layer grown on a relaxed Si0.2Ge0.8 virtual substrate. The self-diffusivity is enhanced by the compressive strain and its behavior is fully consistent with a theoretical prediction of a generalized activation volume model of a simple vacancy mediated diffusion, reported by Aziz et al. [Phys. Rev. B 73, 054101 (2006)]. The activation volume of (-0.65±0.21) times the Ge atomic volume quantitatively describes the observed enhancement due to the compressive biaxial strain very well.

Usefulness of the desaturation–distance ratio from the six-minute walk test for patients with COPD

PubMed Central

Fujimoto, Yukari; Oki, Yutaro; Kaneko, Masahiro; Sakai, Hideki; Misu, Shogo; Yamaguchi, Takumi; Mitani, Yuji; Yasuda, Hisafumi; Ishikawa, Akira

2017-01-01

Purpose A straightforward, noninvasive method is needed to assess emphysema and pulmonary hypertension (PH) in COPD patients. The desaturation–distance ratio (DDR) is an index derived from the distance traveled and level of desaturation during a six-minute walk test (6MWT); it has previously been shown to be associated with percentage of forced expiratory volume in the first second of expiration (%FEV1.0) and percentage of diffusion capacity of the lung for carbon monoxide (%DLCO). The aim of this study was to examine the associations between DDR and emphysema and PH. Patients and methods We collected the following data for 74 stable COPD outpatients: lung function tests (%FEV1.0 and %DLCO), 6MWT distance and desaturation, and area of emphysema on computed tomography (percentage of low attenuation area). Enlargement of the pulmonary artery (PA) was assessed by the ratio of the diameter of the PA to that of the aorta (PA:A ratio) as an index of PH. DDR was calculated by the distance traveled and the degree of desaturation reached during a 6MWT. The relationships between study outcomes were assessed with Spearman’s rank-correlation analysis. Receiver operating characteristic (ROC) curves were used to determine the threshold values with the optimum cutoff points for predicting severe or very severe airway obstruction, pulmonary diffusing capacity disorder, moderate or severe emphysema, and enlargement of the PA. Results DDR correlated significantly with %FEV1.0, %DLCO, %LAA, and PA:A ratio. DDR showed high accuracy (area under the ROC curve >0.7) for predicting severe or very severe airway obstruction, pulmonary diffusing capacity disorder, moderate or severe emphysema, and enlargement of the PA. Conclusion The results suggest that DDR is a good index of emphysema and PH in COPD patients. The 6MWT is widely used to assess COPD, and DDR could help with the early diagnosis of COPD. PMID:28919734

DCE-MRI-Derived Volume Transfer Constant (Ktrans) and DWI Apparent Diffusion Coefficient as Predictive Markers of Short- and Long-Term Efficacy of Chemoradiotherapy in Patients With Esophageal Cancer.

PubMed

Ye, Zhi-Min; Dai, Shu-Jun; Yan, Feng-Qin; Wang, Lei; Fang, Jun; Fu, Zhen-Fu; Wang, Yue-Zhen

2018-01-01

This study aimed to evaluate both the short- and long-term efficacies of chemoradiotherapy in relation to the treatment of esophageal cancer . This was achieved through the use of dynamic contrast-enhanced magnetic resonance imaging-derived volume transfer constant and diffusion weighted imaging-derived apparent diffusion coefficient . Patients with esophageal cancer were assigned into the sensitive and resistant groups based on respective efficacies in chemoradiotherapy. Dynamic contrast-enhanced magnetic resonance imaging and diffusion weighted imaging were used to measure volume transfer constant and apparent diffusion coefficient, while computed tomography was used to calculate tumor size reduction rate. Pearson correlation analyses were conducted to analyze correlation between volume transfer constant, apparent diffusion coefficient, and the tumor size reduction rate. Receiver operating characteristic curve was constructed to analyze the short-term efficacy of volume transfer constant and apparent diffusion coefficient, while Kaplan-Meier curve was employed for survival rate analysis. Cox proportional hazard model was used for the risk factors for prognosis of patients with esophageal cancer. Our results indicated reduced levels of volume transfer constant, while increased levels were observed in ADC min , ADC mean , and ADC max following chemoradiotherapy. A negative correlation was determined between ADC min , ADC mean , and ADC max , as well as in the tumor size reduction rate prior to chemoradiotherapy, whereas a positive correlation was uncovered postchemoradiotherapy. Volume transfer constant was positively correlated with tumor size reduction rate both before and after chemoradiotherapy. The 5-year survival rate of patients with esophageal cancer having high ADC min , ADC mean , and ADC max and volume transfer constant before chemoradiotherapy was greater than those with respectively lower values. According to the Cox proportional hazard model, ADC mean , clinical stage, degree of differentiation, and tumor stage were all confirmed as being independent risk factors in regard to the prognosis of patients with EC. The findings of this study provide evidence suggesting that volume transfer constant and apparent diffusion coefficient as being tools allowing for the evaluation of both the short- and long-term efficacies of chemoradiotherapy esophageal cancer treatment.

Tuning the Shell Number of Multishelled Metal Oxide Hollow Fibers for Optimized Lithium-Ion Storage.

PubMed

Sun, Jin; Lv, Chunxiao; Lv, Fan; Chen, Shuai; Li, Daohao; Guo, Ziqi; Han, Wei; Yang, Dongjiang; Guo, Shaojun

2017-06-27

Searching the long-life transition-metal oxide (TMO)-based materials for future lithium-ion batteries (LIBs) is still a great challenge because of the mechanical strain resulting from volume change of TMO anodes during the lithiation/delithiation process. To well address this challenging issue, we demonstrate a controlled method for making the multishelled TMO hollow microfibers with tunable shell numbers to achieve the optimal void for efficient lithium-ion storage. Such a particularly designed void can lead to a short diffusion distance for fast diffusion of Li + ions and also withstand a large volume variation upon cycling, both of which are the key for high-performance LIBs. Triple-shelled TMO hollow microfibers are a quite stable anode material for LIBs with high reversible capacities (NiO: 698.1 mA h g -1 at 1 A g -1 ; Co 3 O 4 : 940.2 mA h g -1 at 1 A g -1 ; Fe 2 O 3 : 997.8 mA h g -1 at 1 A g -1 ), excellent rate capability, and stability. The present work opens a way for rational design of the void of multiple shells in achieving the stable lithium-ion storage through the biomass conversion strategy.

In-situ grown CNTs modified SiO2/C composites as anode with improved cycling stability and rate capability for lithium storage

NASA Astrophysics Data System (ADS)

Wang, Siqi; Zhao, Naiqin; Shi, Chunsheng; Liu, Enzuo; He, Chunnian; He, Fang; Ma, Liying

2018-03-01

Silica (SiO2) is regarded as one of the most promising anode materials for lithium ion batteries owing to its high theoretical specific capacity, relatively low operation potentials, abundance, environmental benignity and low cost. However, the low intrinsic electrical conductivity and large volume change of SiO2 during the discharge/charge cycles usually results in poor electrochemical performance. In this work, carbon nanotubes (CNTs) modified SiO2/C composites have been fabricated through an in-situ chemical vapor deposition method. The results show that the electrical conductivity of the SiO2/C/CNTs is visibly enhanced through a robust connection between the CNTs and SiO2/C particles. Compared with the pristine SiO2 and SiO2/C composites, the SiO2/C/CNTs composites display a high initial capacity of 1267.2 mA h g-1. Besides, an excellent cycling stability with the capacity of 315.7 mA h g-1 is achieved after 1000th cycles at a rate of 1 A g-1. The significantly improved electrochemical properties of the SiO2/C/CNTs composites are mainly attributed to the formation of three dimensional CNT networks in the SiO2/C substrate, which can not only shorten the Li-ion diffusion path but also relieve the volume change during the lithium-ion insertion/extraction processes.

Lung Function in Pregnancy in Langerhans Cell Histiocytosis.

PubMed

Radzikowska, Elżbieta; Wiatr, Elżbieta; Franczuk, Monika; Bestry, Iwona; Roszkowski-Śliż, Kazimierz

2018-01-01

Pulmonary Langerhans cell histiocytosis (LCH) is a rare disease, affecting usually young people. The course of the disease is variable. In some pulmonary LCH patients a severe lung destruction and progression in spite of chemotherapy is observed, but in others just a cessation of smoking induces a regression of the disease. In the present study we seek to determine the influence of pregnancy on pulmonary function in LCH patients, an unchartered area of research. We addressed the issue by investigating eight pregnant women out of the 45 women hospitalized with the diagnosis of pulmonary LCH in the period from 2000 to 2015. For five of the eight pregnant women it was the second gestation. The median follow-up period was 120 months (range 72-175 months). Ten healthy children were born by a C-section. Two spontaneous miscarriages in the seventh week of gestation, and one tubal ectopic pregnancy were recorded. We found that pregnancy did not significantly influence pulmonary function assessed by the following indices: forced expiratory volume in 1 s (FEV1), lung vital capacity (VC), total lung capacity (TLC), residual volume (RV), diffusing capacity of the lungs for carbon monoxide (DLCO), and the distance and arterial oxygen saturation in 6-min walk test. Only one patient in the third trimester of pregnancy experienced bilateral pneumothorax, with persistent air leak. In all patients, delivery and postpartum period were uneventful. We conclude that pregnancy in pulmonary LCH patients is safe and not associated with deterioration of pulmonary function or blood oxygenation.

Impact of anaemia on lung function and exercise capacity in patients with stable severe chronic obstructive pulmonary disease.

PubMed

Guo, Jian; Zheng, Cong; Xiao, Qiang; Gong, Sugang; Zhao, Qinhua; Wang, Lan; He, Jing; Yang, Wenlan; Shi, Xue; Sun, Xingguo; Liu, Jinming

2015-10-08

This study intended to search for potential correlations between anaemia in patients with severe chronic obstructive pulmonary disease (COPD; GOLD stage III) and pulmonary function at rest, exercise capacity as well as ventilatory efficiency, using pulmonary function test (PFT) and cardiopulmonary exercise testing (CPET). The study was undertaken at Shanghai Pulmonary Hospital, a tertiary-level centre affiliated to Tongji University. It caters to a large population base within Shanghai and referrals from centres in other cities as well. 157 Chinese patients with stable severe COPD were divided into 2 groups: the anaemia group (haemoglobin (Hb) <12.0 g/dL for males, and <11 g/dL for females (n=48)) and the non-anaemia group (n=109). Arterial blood gas, PFT and CPET were tested in all patients. (1) Diffusing capacity for carbon monoxide (DLCO) corrected by Hb was significantly lower in the anaemia group ((15.3±1.9) mL/min/mm Hg) than in the non-anaemia group ((17.1±2.1) mL/min/mm Hg) (p<0.05). A significant difference did not exist in the level of forced expiratory volume in 1 s (FEV1), FEV1%pred, FEV1/forced vital capacity (FVC), inspiratory capacity (IC), residual volume (RV), total lung capacity (TLC) and RV/TLC (p>0.05). (2) Peak Load, Peak oxygen uptake (VO2), Peak VO2%pred, Peak VO2/kg, Peak O2 pulse and the ratio of VO2 increase to WR increase (ΔVO2/ΔWR) were significantly lower in the anaemia group (p<0.05); however, Peak minute ventilation (VE), Lowest VE/carbon dioxide output (VCO2) and Peak dead space/tidal volume ratio (VD/VT) were similar between the 2 groups (p>0.05). (3) A strong positive correlation was found between Hb concentration and Peak VO2 in patients with anaemia (r=0.702, p<0.01). Anaemia has a negative impact on gas exchange and exercise tolerance during exercise in patients with severe COPD. The decrease in amplitude of Hb levels is related to the quantity of oxygen uptake. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

[Study of the clinical phenotype of symptomatic chronic airways disease by hierarchical cluster analysis and two-step cluster analyses].

PubMed

Ning, P; Guo, Y F; Sun, T Y; Zhang, H S; Chai, D; Li, X M

2016-09-01

To study the distinct clinical phenotype of chronic airway diseases by hierarchical cluster analysis and two-step cluster analysis. A population sample of adult patients in Donghuamen community, Dongcheng district and Qinghe community, Haidian district, Beijing from April 2012 to January 2015, who had wheeze within the last 12 months, underwent detailed investigation, including a clinical questionnaire, pulmonary function tests, total serum IgE levels, blood eosinophil level and a peak flow diary. Nine variables were chosen as evaluating parameters, including pre-salbutamol forced expired volume in one second(FEV1)/forced vital capacity(FVC) ratio, pre-salbutamol FEV1, percentage of post-salbutamol change in FEV1, residual capacity, diffusing capacity of the lung for carbon monoxide/alveolar volume adjusted for haemoglobin level, peak expiratory flow(PEF) variability, serum IgE level, cumulative tobacco cigarette consumption (pack-years) and respiratory symptoms (cough and expectoration). Subjects' different clinical phenotype by hierarchical cluster analysis and two-step cluster analysis was identified. (1) Four clusters were identified by hierarchical cluster analysis. Cluster 1 was chronic bronchitis in smokers with normal pulmonary function. Cluster 2 was chronic bronchitis or mild chronic obstructive pulmonary disease (COPD) patients with mild airflow limitation. Cluster 3 included COPD patients with heavy smoking, poor quality of life and severe airflow limitation. Cluster 4 recognized atopic patients with mild airflow limitation, elevated serum IgE and clinical features of asthma. Significant differences were revealed regarding pre-salbutamol FEV1/FVC%, pre-salbutamol FEV1% pred, post-salbutamol change in FEV1%, maximal mid-expiratory flow curve(MMEF)% pred, carbon monoxide diffusing capacity per liter of alveolar(DLCO)/(VA)% pred, residual volume(RV)% pred, total serum IgE level, smoking history (pack-years), St.George's respiratory questionnaire(SGRQ) score, acute exacerbation in the past one year, PEF variability and allergic dermatitis (P<0.05). (2) Four clusters were also identified by two-step cluster analysis as followings, cluster 1, COPD patients with moderate to severe airflow limitation; cluster 2, asthma and COPD patients with heavy smoking, airflow limitation and increased airways reversibility; cluster 3, patients having less smoking and normal pulmonary function with wheezing but no chronic cough; cluster 4, chronic bronchitis patients with normal pulmonary function and chronic cough. Significant differences were revealed regarding gender distribution, respiratory symptoms, pre-salbutamol FEV1/FVC%, pre-salbutamol FEV1% pred, post-salbutamol change in FEV1%, MMEF% pred, DLCO/VA% pred, RV% pred, PEF variability, total serum IgE level, cumulative tobacco cigarette consumption (pack-years), and SGRQ score (P<0.05). By different cluster analyses, distinct clinical phenotypes of chronic airway diseases are identified. Thus, individualized treatments may guide doctors to provide based on different phenotypes.

Morphological Pulmonary Diffusion Capacity for Oxygen of Burmese Pythons (Python molurus): a Comparison of Animals in Healthy Condition and with Different Pulmonary Infections.

PubMed

Starck, J M; Weimer, I; Aupperle, H; Müller, K; Marschang, R E; Kiefer, I; Pees, M

2015-11-01

A qualitative and quantitative morphological study of the pulmonary exchange capacity of healthy and diseased Burmese pythons (Python molurus) was carried out in order to test the hypothesis that the high morphological excess capacity for oxygen exchange in the lungs of these snakes is one of the reasons why pathological processes extend throughout the lung parenchyma and impair major parts of the lungs before clinical signs of respiratory disease become apparent. Twenty-four Burmese pythons (12 healthy and 12 diseased) were included in the study. A stereology-based approach was used to quantify the lung parenchyma using computed tomography. Light microscopy was used to quantify tissue compartments and the respiratory exchange surface, and transmission electron microscopy was used to measure the thickness of the diffusion barrier. The morphological diffusion capacity for oxygen of the lungs and the anatomical diffusion factor were calculated. The calculated anatomical diffusion capacity was compared with published values for oxygen consumption of healthy snakes, and the degree to which the exchange capacity can be obstructed before normal physiological function is impaired was estimated. Heterogeneous pulmonary infections result in graded morphological transformations of pulmonary parenchyma involving lymphocyte migration into the connective tissue and thickening of the septal connective tissue, increasing thickness of the diffusion barrier and increasing transformation of the pulmonary epithelium into a columnar pseudostratified or stratified epithelium. The transformed epithelium developed by hyperplasia of ciliated cells arising from the tip of the faveolar septa and by hyperplasia of type II pneumocytes. These results support the idea that the lungs have a remarkable overcapacity for oxygen consumption and that the development of pulmonary disease continuously reduces the capacity for oxygen consumption. However, due to the overcapacity of the lungs, this reduction does not result in clinical signs and disease can progress unrecognized for an extended period. Copyright © 2015 Elsevier Ltd. All rights reserved.

Emphysema Distribution and Diffusion Capacity Predict Emphysema Progression in Human Immunodeficiency Virus Infection

PubMed Central

Leung, Janice M; Malagoli, Andrea; Santoro, Antonella; Besutti, Giulia; Ligabue, Guido; Scaglioni, Riccardo; Dai, Darlene; Hague, Cameron; Leipsic, Jonathon; Sin, Don D.; Man, SF Paul; Guaraldi, Giovanni

2016-01-01

Background Chronic obstructive pulmonary disease (COPD) and emphysema are common amongst patients with human immunodeficiency virus (HIV). We sought to determine the clinical factors that are associated with emphysema progression in HIV. Methods 345 HIV-infected patients enrolled in an outpatient HIV metabolic clinic with ≥2 chest computed tomography scans made up the study cohort. Images were qualitatively scored for emphysema based on percentage involvement of the lung. Emphysema progression was defined as any increase in emphysema score over the study period. Univariate analyses of clinical, respiratory, and laboratory data, as well as multivariable logistic regression models, were performed to determine clinical features significantly associated with emphysema progression. Results 17.4% of the cohort were emphysema progressors. Emphysema progression was most strongly associated with having a low baseline diffusion capacity of carbon monoxide (DLCO) and having combination centrilobular and paraseptal emphysema distribution. In adjusted models, the odds ratio (OR) for emphysema progression for every 10% increase in DLCO percent predicted was 0.58 (95% confidence interval [CI] 0.41–0.81). The equivalent OR (95% CI) for centrilobular and paraseptal emphysema distribution was 10.60 (2.93–48.98). Together, these variables had an area under the curve (AUC) statistic of 0.85 for predicting emphysema progression. This was an improvement over the performance of spirometry (forced expiratory volume in 1 second to forced vital capacity ratio), which predicted emphysema progression with an AUC of only 0.65. Conclusion Combined paraseptal and centrilobular emphysema distribution and low DLCO could identify HIV patients who may experience emphysema progression. PMID:27902753

Evaluation of Proteins' Rotational Diffusion Coefficients from Simulations of Their Free Brownian Motion in Volume-Occupied Environments.

PubMed

Długosz, Maciej; Antosiewicz, Jan M

2014-01-14

We have investigated the rotational dynamics of hen egg white lysozyme in monodisperse aqueous solutions of concentrations up to 250 mg/mL, using a rigid-body Brownian dynamics method that accurately accounts for anisotropies of diffusing objects. We have examined the validity of the free diffusion concept in the analysis of computer simulations of volume-occupied molecular solutions. We have found that, when as the only intermolecular interaction, the excluded volume effect is considered, rotational diffusion of molecules adheres to the free diffusion model. Further, we present a method based on the exact (in the case of the free diffusion) analytic forms of autocorrelation functions of particular vectors rigidly attached to diffusing objects, which allows one to obtain from results of molecular simulations the three principal rotational diffusion coefficients characterizing rotational Brownian motion of an arbitrarily shaped rigid particle for an arbitrary concentration of crowders. We have applied this approach to trajectories resulting from Brownian dynamics simulations of hen egg white lysozyme solutions. We show that the apparent anisotropy of proteins' rotational motions increases with an increasing degree of crowding. Finally, we demonstrate that even if the hydrodynamic anisotropy of molecules is neglected and molecules are simulated using their average translational and rotational diffusion coefficients, excluded volume effects still lead to their anisotropic rotational dynamics.

Multi-modal neuroimaging in premanifest and early Huntington's disease: 18 month longitudinal data from the IMAGE-HD study.

PubMed

Domínguez D, Juan F; Egan, Gary F; Gray, Marcus A; Poudel, Govinda R; Churchyard, Andrew; Chua, Phyllis; Stout, Julie C; Georgiou-Karistianis, Nellie

2013-01-01

IMAGE-HD is an Australian based multi-modal longitudinal magnetic resonance imaging (MRI) study in premanifest and early symptomatic Huntington's disease (pre-HD and symp-HD, respectively). In this investigation we sought to determine the sensitivity of imaging methods to detect macrostructural (volume) and microstructural (diffusivity) longitudinal change in HD. We used a 3T MRI scanner to acquire T1 and diffusion weighted images at baseline and 18 months in 31 pre-HD, 31 symp-HD and 29 controls. Volume was measured across the whole brain, and volume and diffusion measures were ascertained for caudate and putamen. We observed a range of significant volumetric and, for the first time, diffusion changes over 18 months in both pre-HD and symp-HD, relative to controls, detectable at the brain-wide level (volume change in grey and white matter) and in caudate and putamen (volume and diffusivity change). Importantly, longitudinal volume change in the caudate was the only measure that discriminated between groups across all stages of disease: far from diagnosis (>15 years), close to diagnosis (<15 years) and after diagnosis. Of the two diffusion metrics (mean diffusivity, MD; fractional anisotropy, FA), only longitudinal FA change was sensitive to group differences, but only after diagnosis. These findings further confirm caudate atrophy as one of the most sensitive and early biomarkers of neurodegeneration in HD. They also highlight that different tissue properties have varying schedules in their ability to discriminate between groups along disease progression and may therefore inform biomarker selection for future therapeutic interventions.

Self-diffusion of polycrystalline ice Ih under confining pressure: Hydrogen isotope analysis using 2-D Raman imaging

NASA Astrophysics Data System (ADS)

Noguchi, Naoki; Kubo, Tomoaki; Durham, William B.; Kagi, Hiroyuki; Shimizu, Ichiko

2016-08-01

We have developed a high-resolution technique based on micro Raman spectroscopy to measure hydrogen isotope diffusion profiles in ice Ih. The calibration curve for quantitative analysis of deuterium in ice Ih was constructed using micro Raman spectroscopy. Diffusion experiments using diffusion couples composed of dense polycrystalline H2O and D2O ice were carried out under a gas confining pressure of 100 MPa (to suppress micro-fracturing and pore formation) at temperatures from 235 K to 245 K and diffusion times from 0.2 to 94 hours. Two-dimensional deuterium profiles across the diffusion couples were determined by Raman imaging. The location of small spots of frost from room air could be detected from the shapes of the Raman bands of OH and OD stretching modes, which change because of the effect of the molar ratio of deuterium on the molecular coupling interaction. We emphasize the validity for screening the impurities utilizing the coupling interaction. Some recrystallization and grain boundary migration occurred in recovered diffusion couples, but analysis of two-dimensional diffusion profiles of regions not affected by grain boundary migration allowed us to measure a volume diffusivity for ice at 100 MPa of (2.8 ± 0.4) ×10-3exp[ -57.0 ± 15.4kJ /mol RT ] m2 /s (R is the gas constant, T is temperature). Based on ambient pressure diffusivity measurements by others, this value indicates a high (negative) activation volume for volume diffusivity of -29.5 cm3/mol or more. We can also constrain the value of grain boundary diffusivity in ice at 100 MPa to be <104 that of volume diffusivity.

Sb lattice diffusion in Si1-xGex/Si(001) heterostructures: Chemical and stress effects

NASA Astrophysics Data System (ADS)

Portavoce, A.; Gas, P.; Berbezier, I.; Ronda, A.; Christensen, J. S.; Kuznetsov, A. Yu.; Svensson, B. G.

2004-04-01

The Sb diffusion coefficient in Si1-xGex/Si1-yGey(001) heterostructures grown by molecular beam epitaxy (MBE) was measured for temperatures ranging from 700 to 850 °C, Ge composition from 0 to 20 % and biaxial pressure from -0.8 (tension) to 1.4 GPa (compression). A quantitative separation of composition and biaxial stress effects is made. We show that the Sb lattice diffusion coefficient: (i) increases with Ge concentration in relaxed layers or at constant biaxial pressure and (ii) increases with compressive biaxial stress and decreases with tensile biaxial stress at constant Ge composition. The enhancement of Sb lattice diffusion in Si1-xGex layers in epitaxy on Si(001) is thus due to the cooperative effect of Ge composition and induced compressive biaxial stress. However, the first effect (composition) is predominant. The activation volume of Sb diffusion in Si1-xGex layers is deduced from the variation of the Sb diffusion coefficients with biaxial pressure. This volume is negative. The sign of the activation volume, its absolute value and its variation with temperature confirm the prediction of the thermodynamic model proposed by Aziz, namely, that under a biaxial stress the activation volume is reduced to the relaxation volume.

Core-shell structured MnSiO3 supported with CNTs as a high capacity anode for lithium-ion batteries.

PubMed

Feng, Jing; Li, Qin; Wang, Huijun; Zhang, Min; Yang, Xia; Yuan, Ruo; Chai, Yaqin

2018-04-17

Metal silicates are good candidates for use in lithium ion batteries (LIBs), however, their electrochemical performance is hindered by their poor electrical conductivity and volume expansion during Li+ insertion/desertion. In this work, one-dimensional core-shell structured MnSiO3 supported with carbon nanotubes (CNTs) (referred to as CNT@MnSiO3) with good conductivity and electrochemical performance has been successfully synthesized using a solvothermal process under moderate conditions. In contrast to traditional composites of CNTs and nanoparticles, the CNT@MnSiO3 composite in this work is made up of CNTs with a layer of MnSiO3 on the surface. The one-dimensional CNT@MnSiO3 nanotubes provide a useful channel for transferring Li+ ions during the discharge/charge process, which accelerates the Li+ diffusion speed. The CNTs inside the structure not only enhance the conductivity of the composite, but also prevent volume expansion. A high reversible capacity (920 mA h g-1 at 500 mA g-1 over 650 cycles) and good rate performance were obtained for CNT@MnSiO3, showing that this strategy of synthesizing coaxial CNT@MnSiO3 nanotubes offers a promising method for preparing other silicates for LIBs or other applications.

The hematocrit paradox--how does blood doping really work?

PubMed

Böning, D; Maassen, N; Pries, A

2011-04-01

The wide-spread assumption that doping with erythropoietin or blood transfusion is only effective by increasing arterial blood O2 content because of rising hematocrit is not self-evident. "Natural blood dopers" (horses, dogs) increase both hematocrit and circulating blood volume during exercise by releasing stored erythrocytes from the spleen. Improvement of aerobic performance by augmenting hemoglobin concentration may be expected until the optimal hematocrit is reached; above this value maximal cardiac output declines due to the steep increase of blood viscosity. Therefore an enlarged blood oxygen content might only be useful if the normal hematocrit of man during exercise is suboptimal. However, recent studies suggest that cardiac power rises after erythropoietin allowing an unchanged cardiac output in spite of increased viscosity. Other factors underlying improved performance after blood doping might be: augmented diffusion capacity for oxygen in lungs and tissues, increased percentage of young red cells with good functional properties (after erythropoietin), increased buffer capacity, increase of blood volume, vasoconstriction, reduced damage by radicals, mood improvement by cerebral effects of erythropoietin. Also the importance of placebo is unknown since double-blind studies are rare. It is suggested that blood doping has multifactorial effects not restricted to the increase in arterial oxygen content. © Georg Thieme Verlag KG Stuttgart · New York.

Physical re-examination of parameters on a molecular collisions-based diffusion model for diffusivity prediction in polymers.

PubMed

Ohashi, Hidenori; Tamaki, Takanori; Yamaguchi, Takeo

2011-12-29

Molecular collisions, which are the microscopic origin of molecular diffusive motion, are affected by both the molecular surface area and the distance between molecules. Their product can be regarded as the free space around a penetrant molecule defined as the "shell-like free volume" and can be taken as a characteristic of molecular collisions. On the basis of this notion, a new diffusion theory has been developed. The model can predict molecular diffusivity in polymeric systems using only well-defined single-component parameters of molecular volume, molecular surface area, free volume, and pre-exponential factors. By consideration of the physical description of the model, the actual body moved and which neighbor molecules are collided with are the volume and the surface area of the penetrant molecular core. In the present study, a semiempirical quantum chemical calculation was used to calculate both of these parameters. The model and the newly developed parameters offer fairly good predictive ability. © 2011 American Chemical Society

Prediction of stream volatilization coefficients

USGS Publications Warehouse

Rathbun, Ronald E.

1990-01-01

Equations are developed for predicting the liquid-film and gas-film reference-substance parameters for quantifying volatilization of organic solutes from streams. Molecular weight and molecular-diffusion coefficients of the solute are used as correlating parameters. Equations for predicting molecular-diffusion coefficients of organic solutes in water and air are developed, with molecular weight and molal volume as parameters. Mean absolute errors of prediction for diffusion coefficients in water are 9.97% for the molecular-weight equation, 6.45% for the molal-volume equation. The mean absolute error for the diffusion coefficient in air is 5.79% for the molal-volume equation. Molecular weight is not a satisfactory correlating parameter for diffusion in air because two equations are necessary to describe the values in the data set. The best predictive equation for the liquid-film reference-substance parameter has a mean absolute error of 5.74%, with molal volume as the correlating parameter. The best equation for the gas-film parameter has a mean absolute error of 7.80%, with molecular weight as the correlating parameter.

CoMn2O4 Spinel Hierarchical Microspheres Assembled with Porous Nanosheets as Stable Anodes for Lithium-ion Batteries

PubMed Central

Hu, Lin; Zhong, Hao; Zheng, Xinrui; Huang, Yimin; Zhang, Ping; Chen, Qianwang

2012-01-01

Herein, we report the feasibility to enhance the capacity and stability of CoMn2O4 anode materials by fabricating hierarchical mesoporous structure. The open space between neighboring nanosheets allows for easy diffusion of the electrolyte. The hierarchical microspheres assembled with nanosheets can ensure that every nanosheet participates in the electrochemical reaction, because every nanosheet is contacted with the electrolyte solution. The hierarchical structure and well interconnected pores on the surface of nanosheets will enhance the CoMn2O4/electrolyte contact area, shorten the Li+ ion diffusion length in the nanosheets, and accommodate the strain induced by the volume change during the electrochemical reaction. The last, hierarchical architecture with spherical morphology possesses relatively low surface energy, which results in less extent of self-aggregation during charge/discharge process. As a result, CoMn2O4 hierarchical microspheres can achieve a good cycle ability and high rate capability. PMID:23248749

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanchez-Nieto, Beatriz, E-mail: bsanchez@fis.puc.cl; Goset, Karen C.; Caviedes, Ivan

Purpose: To propose multivariate predictive models for changes in pulmonary function tests ({Delta}PFTs) with respect to preradiotherapy (pre-RT) values in patients undergoing RT for breast cancer and lymphoma. Methods and Materials: A prospective study was designed to measure {Delta}PFTs of patients undergoing RT. Sixty-six patients were included. Spirometry, lung capacity (measured by helium dilution), and diffusing capacity of carbon monoxide tests were used to measure lung function. Two lung definitions were considered: paired lung vs. irradiated lung (IL). Correlation analysis of dosimetric parameters (mean lung dose and the percentage of lung volume receiving more than a threshold dose) and {Delta}PFTsmore » was carried out to find the best dosimetric predictor. Chemotherapy, age, smoking, and the selected dose-volume parameter were considered as single and interaction terms in a multivariate analysis. Stability of results was checked by bootstrapping. Results: Both lung definitions proved to be similar. Modeling was carried out for IL. Acute and late damage showed the highest correlations with volumes irradiated above {approx}20 Gy (maximum R{sup 2} = 0.28) and {approx}40 Gy (maximum R{sup 2} = 0.21), respectively. RT alone induced a minor and transitory restrictive defect (p = 0.013). Doxorubicin-cyclophosphamide-paclitaxel (Taxol), when administered pre-RT, induced a late, large restrictive effect, independent of RT (p = 0.031). Bootstrap values confirmed the results. Conclusions: None of the dose-volume parameters was a perfect predictor of outcome. Thus, different predictor models for {Delta}PFTs were derived for the IL, which incorporated other nondosimetric parameters mainly through interaction terms. Late {Delta}PFTs seem to behave more serially than early ones. Large restrictive defects were demonstrated in patients pretreated with doxorubicin-cyclophosphamide-paclitaxel.« less

Influence of pulmonary emphysema on COPD assessment test-oriented categorization in GOLD document.

PubMed

Suzuki, Toshio; Tada, Yuji; Kawata, Naoko; Ikari, Jun; Kasahara, Yasunori; Sakurai, Yoriko; Iesato, Ken; Nishimura, Rintaro; West, James; Tatsumi, Koichiro

2015-01-01

The COPD assessment test (CAT) score is a key component of the multifactorial assessment of COPD in the Global initiative for chronic Obstructive Lung Disease (GOLD) guidelines of 2014. Nevertheless, little is known regarding the differences among COPD categories in terms of clinical parameters such as pulmonary function or radiological findings. Thus, our aims in this study were to evaluate the associations between CAT scores and pulmonary clinical parameters, and to investigate factors that could discriminate between a "less symptomatic group" (categories A and C) and a "more symptomatic group" (categories B and D) among stable COPD patients. We enrolled 200 outpatients at Chiba University Hospital. Study subjects were assessed by CAT, pulmonary function testing, and multidetector computed tomography (MDCT). We assessed possible correlations between these indices. CAT scores were negatively correlated with percentage of the forced expiratory volume in 1 second predicted value (FEV1 %predicted) and percentage of the diffusing capacity for carbon monoxide per liter of lung volume predicted value (DLCO/VA [%predicted]) results and positively correlated with low attenuation volume percentage (LAV%) and residual volume to total lung capacity ratios (RV/TLC). In the "more symptomatic group" (category B or D), the mean DLCO/VA (%predicted) was significantly lower and the mean LAV% and RV/TLC was significantly higher than those in the "less symptomatic group" (category A or C), respectively. Interestingly, those in category B had higher mean LAV% compared to those in category C. CAT scores were significantly correlated with pulmonary function parameters and emphysematous changes on MDCT. The new GOLD classification system would be a step toward a phenotypic approach, especially taking into account the degree of emphysema and hyperinflation.

Measurable Supratentorial White Matter Volume Changes in Patients with Diffuse Intrinsic Pontine Glioma Treated with an Anti-Vascular Endothelial Growth Factor Agent, Steroids, and Radiation.

PubMed

Svolos, P; Reddick, W E; Edwards, A; Sykes, A; Li, Y; Glass, J O; Patay, Z

2017-06-01

Assessing the response to treatment in infiltrative brain tumors by using lesion volume-based response criteria is challenging. We hypothesized that in such tumors, volume measurements alone may not accurately capture changes in actual tumor burden during treatment. We longitudinally evaluated volume changes in both normal-appearing supratentorial white matter and the brain stem lesions in patients treated for diffuse intrinsic pontine glioma to determine to what extent adjuvant systemic therapies may skew the accuracy of tumor response assessments based on volumetric analysis. The anatomic MR imaging and diffusion tensor imaging data of 26 patients with diffuse intrinsic pontine glioma were retrospectively analyzed. Treatment included conformal radiation therapy in conjunction with vandetanib and dexamethasone. Volumetric and diffusion data were analyzed with time, and differences between time points were evaluated statistically. Normalized brain stem lesion volume decreased during combined treatment (slope = -0.222, P < .001) and increased shortly after completion of radiation therapy (slope = 0.422, P < .001). Supratentorial white matter volume steadily and significantly decreased with time (slope = -0.057, P < .001). Longitudinal changes in brain stem lesion volume are robust; less pronounced but measurable changes occur in the supratentorial white matter. Volume changes in nonirradiated supratentorial white matter during the disease course reflect the effects of systemic medication on the water homeostasis of normal parenchyma. Our data suggest that adjuvant nontumor-targeted therapies may have a more substantial effect on lesion volume changes than previously thought; hence, an apparent volume decrease in infiltrative tumors receiving combined therapies may lead to overestimation of the actual response and tumor control. © 2017 by American Journal of Neuroradiology.

Tissue microstructure features derived from anomalous diffusion measurements in magnetic resonance imaging.

PubMed

Yu, Qiang; Reutens, David; O'Brien, Kieran; Vegh, Viktor

2017-02-01

Tissue microstructure features, namely axon radius and volume fraction, provide important information on the function of white matter pathways. These parameters vary on the scale much smaller than imaging voxels (microscale) yet influence the magnetic resonance imaging diffusion signal at the image voxel scale (macroscale) in an anomalous manner. Researchers have already mapped anomalous diffusion parameters from magnetic resonance imaging data, but macroscopic variations have not been related to microscale influences. With the aid of a tissue model, we aimed to connect anomalous diffusion parameters to axon radius and volume fraction using diffusion-weighted magnetic resonance imaging measurements. An ex vivo human brain experiment was performed to directly validate axon radius and volume fraction measurements in the human brain. These findings were validated using electron microscopy. Additionally, we performed an in vivo study on nine healthy participants to map axon radius and volume fraction along different regions of the corpus callosum projecting into various cortical areas identified using tractography. We found a clear relationship between anomalous diffusion parameters and axon radius and volume fraction. We were also able to map accurately the trend in axon radius along the corpus callosum, and in vivo findings resembled the low-high-low-high behaviour in axon radius demonstrated previously. Axon radius and volume fraction measurements can potentially be used in brain connectivity studies and to understand the implications of white matter structure in brain diseases and disorders. Hum Brain Mapp 38:1068-1081, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Astrocytes and extracellular matrix in extrasynaptic volume transmission.

PubMed

Vargová, Lýdia; Syková, Eva

2014-10-19

Volume transmission is a form of intercellular communication that does not require synapses; it is based on the diffusion of neuroactive substances across the brain extracellular space (ECS) and their binding to extrasynaptic high-affinity receptors on neurons or glia. Extracellular diffusion is restricted by the limited volume of the ECS, which is described by the ECS volume fraction α, and the presence of diffusion barriers, reflected by tortuosity λ, that are created, for example, by fine astrocytic processes or extracellular matrix (ECM) molecules. Organized astrocytic processes, ECM scaffolds or myelin sheets channel the extracellular diffusion so that it is facilitated in a certain direction, i.e. anisotropic. The diffusion properties of the ECS are profoundly influenced by various processes such as the swelling and morphological rebuilding of astrocytes during either transient or persisting physiological or pathological states, or the remodelling of the ECM in tumorous or epileptogenic tissue, during Alzheimer's disease, after enzymatic treatment or in transgenic animals. The changing diffusion properties of the ECM influence neuron-glia interaction, learning abilities, the extent of neuronal damage and even cell migration. From a clinical point of view, diffusion parameter changes occurring during pathological states could be important for diagnosis, drug delivery and treatment. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Porous carbon nanotubes decorated with nanosized cobalt ferrite as anode materials for high-performance lithium-ion batteries

NASA Astrophysics Data System (ADS)

Wang, Lingyan; Zhuo, Linhai; Cheng, Haiyang; Zhang, Chao; Zhao, Fengyu

2015-06-01

Generally, the fast ion/electron transport and structural stability dominate the superiority in lithium-storage applications. In this work, porous carbon nanotubes decorated with nanosized CoFe2O4 particles (p-CNTs@CFO) have been rationally designed and synthesized by the assistance of supercritical carbon dioxide (scCO2). When tested as anode materials for lithium-ion batteries, the p-CNTs@CFO composite exhibits outstanding electrochemical behavior with high lithium-storage capacity (1077 mAh g-1 after 100 cycles) and rate capability (694 mAh g-1 at 3 A g-1). These outstanding electrochemical performances are attributed to the synergistic effect of porous p-CNTs and nanosized CFO. Compared to pristine CNTs, the p-CNTs with substantial pores in the tubes possess largely increased specific surface area and rich oxygen-containing functional groups. The porous structure can not only accommodate the volume change during lithiation/delithiation processes, but also provide bicontinuous electron/ion pathways and large electrode/electrolyte interface, which facilitate the ion diffusion kinetics, improving the rate performance. Moreover, the CFO particles are bonded strongly to the p-CNTs through metal-oxygen bridges, which facilitate the electron fast capture from p-CNTs to CFO, and thus resulting in a high reversible capacity and excellent rate performance. Overall, the porous p-CNTs provide an efficient way for ion diffusion and continuous electron transport as anode materials.

Activation volume for phosphorus diffusion in silicon and Si0.93Ge0.07

NASA Astrophysics Data System (ADS)

Zhao, Yuechao; Aziz, Michael J.; Zangenberg, Nikolaj R.; Larsen, Arne Nylandsted

2005-04-01

The hydrostatic pressure dependence of the diffusivity of P in compressively strained Si0.93Ge0.07 and unalloyed Si has been measured. In both cases the diffusivity is almost independent of pressure, characterized by an activation volume V* of (+0.09±0.11) times the atomic volume Ω for the unalloyed Si, and (+0.01±0.06) Ω for Si0.93Ge0.07. The results are used in conjunction with the reported effect of biaxial strain on diffusion normal to the surface to test the prediction for an interstitialcy-based mechanism of Aziz's phenomenological thermodynamic treatment of diffusion under uniform nonhydrostatic stress states. The prediction agrees well with measured behavior, lending additional credence to the interstitial-based mechanism and supporting the nonhydrostatic thermodynamic treatment.

Activation Volume for Hf Diffusion in an Amorphous Ni{sub 0.54}Zr{sub 0.46} Alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grandjean, A.; Limoge, Y.; Blanchard, P.

In this Letter we present the results of a diffusion study of Hf in a Ni{sub 0.54}Zr{sub 0.46} amorphous alloy. We have measured the diffusion properties with and without pressure, up to 1GPa. From these measurements we can deduce an Arrhenius behavior of the diffusion, with an activation energy of 0.76eV and a pre-exponential factor of 7.4{times}10{sup -17}m{sup 2}/s. The activation volume amounts to 8.5{angstrom};{sup 3}. Activation volume and energy are related by the Keyes relationship. We then discuss to what extent presently proposed diffusion mechanisms, point defects, or collective processes can be tested against these results. {copyright} {ital 1997}more » {ital The American Physical Society}« less

Can lung volumes and capacities be used as an outcome measure for phrenic nerve recovery after cardiac surgeries?

PubMed

El-Sobkey, Salwa B; Salem, Naguib A

2011-01-01

Phrenic nerve is the main nerve drive to the diaphragm and its injury is a well-known complication following cardiac surgeries. It results in diaphragmatic dysfunction with reduction in lung volumes and capacities. This study aimed to evaluate the objectivity of lung volumes and capacities as an outcome measure for the prognosis of phrenic nerve recovery after cardiac surgeries. In this prospective experimental study, patients were recruited from Cardio-Thoracic Surgery Department, Educational-Hospital of College of Medicine, Cairo University. They were 11 patients with right phrenic nerve injury and 14 patients with left injury. On the basis of receiving low-level laser irradiation, they were divided into irradiated group and non-irradiated group. Measures of phrenic nerve latency, lung volumes and capacities were taken pre and post-operative and at 3-months follow up. After 3 months of low-level laser therapy, the irradiated group showed marked improvement in the phrenic nerve recovery. On the other hand, vital capacity and forced expiratory volume in the first second were the only lung capacity and volume that showed improvement consequent with the recovery of right phrenic nerve (P value <0.001 for both). Furthermore, forced vital capacity was the single lung capacity that showed significant statistical improvement in patients with recovered left phrenic nerve injury (P value <0.001). Study concluded that lung volumes and capacities cannot be used as an objective outcome measure for recovery of phrenic nerve injury after cardiac surgeries.

Study on low intensity aeration oxygenation model and optimization for shallow water

NASA Astrophysics Data System (ADS)

Chen, Xiao; Ding, Zhibin; Ding, Jian; Wang, Yi

2018-02-01

Aeration/oxygenation is an effective measure to improve self-purification capacity in shallow water treatment while high energy consumption, high noise and expensive management refrain the development and the application of this process. Based on two-film theory, the theoretical model of the three-dimensional partial differential equation of aeration in shallow water is established. In order to simplify the equation, the basic assumptions of gas-liquid mass transfer in vertical direction and concentration diffusion in horizontal direction are proposed based on engineering practice and are tested by the simulation results of gas holdup which are obtained by simulating the gas-liquid two-phase flow in aeration tank under low-intensity condition. Based on the basic assumptions and the theory of shallow permeability, the model of three-dimensional partial differential equations is simplified and the calculation model of low-intensity aeration oxygenation is obtained. The model is verified through comparing the aeration experiment. Conclusions as follows: (1)The calculation model of gas-liquid mass transfer in vertical direction and concentration diffusion in horizontal direction can reflect the process of aeration well; (2) Under low-intensity conditions, the long-term aeration and oxygenation is theoretically feasible to enhance the self-purification capacity of water bodies; (3) In the case of the same total aeration intensity, the effect of multipoint distributed aeration on the diffusion of oxygen concentration in the horizontal direction is obvious; (4) In the shallow water treatment, reducing the volume of aeration equipment with the methods of miniaturization, array, low-intensity, mobilization to overcome the high energy consumption, large size, noise and other problems can provide a good reference.

The rise in carboxyhemoglobin from repeated pulmonary diffusing capacity tests.

PubMed

Zavorsky, Gerald S

2013-03-01

The purpose of this study determined the rise in carboxyhemoglobin percentage (COHb) from repeated pulmonary diffusing capacity tests using 5 or 10s single breath-hold maneuvers. Five male and four female non-smokers [baseline COHb=1.2 (SD 0.5%)] performed repeated pulmonary diffusing capacity testing on two separate days. The days were randomized to either repeated 10s (0.28% CO), or 5s (0.28% CO, 55ppm NO) breath-hold maneuvers. Twenty-two 5s breath-hold maneuvers, each separated by 4min rest, raised COHb to 11.1 (1.4)% and minimally raised the methemoglobin percentage (METHb) by 0.3 (0.2)% to a value of 0.8 (0.2)%. After the 22nd test, pulmonary diffusing capacity for carbon monoxide (DLCO) was reduced by about 4mL/min/mmHg, equating to a 0.44% increase in COHb per 5s breath-hold maneuver and a concomitant 0.35mL/min/mmHg decrease in DLCO. Pulmonary diffusing capacity for nitric oxide (DLNO) was not altered after 22 tests. On another day, the 10s single breath-hold maneuver increased COHb by 0.64% per test, and reduced DLCO by 0.44mL/min/mmHg per test. In conclusion, 5s breath-hold maneuvers do not appreciably raise METHb or DLNO, and DLCO is only significantly reduced when COHb is at least 6%. Copyright © 2013 Elsevier B.V. All rights reserved.

Standard Partial Molar Heat Capacities and Volumes of Barium and Cadmium Ions in Dimethylsulfoxide at 298.15 K

NASA Astrophysics Data System (ADS)

Novikov, A. N.; Doronin, Ya. I.; Rakhmanova, P. A.

2018-07-01

The heat capacities and volumes of dimethylsulfoxide (DMSO) solutions of barium and cadmium iodides at 298.15 K were measured by calorimetry and densimetry. The standard partial molar heat capacities \\bar C_{p,2}^° and volumes \\bar V2^° of BaI2 and CdI2 in DMSO were calculated. The standard heat capacities \\bar C_{p,i}^° and volumes \\bar {V}i^° of barium and cadmium ions in DMSO at 298.15 K were determined.

Transscleral diffusion of ethacrynic acid and sodium fluorescein

PubMed Central

Lin, Cheng-Wen; Wang, Yong; Challa, Pratap; Epstein, David L.

2007-01-01

Purpose One of the current limitations in developing novel glaucoma drugs that target the trabecular meshwork (TM) is the induced corneal toxicity from eyedrop formulations. To avoid the corneal toxicity, an alternative approach would be to deliver TM drugs through the sclera. To this end, we quantified ex vivo diffusion coefficient of a potential TM drug, ethacrynic acid (ECA), and investigated mechanisms of ECA transport in the sclera. Methods An Ussing-type diffusion apparatus was built to measure the apparent diffusion coefficient of ECA in fresh porcine sclera at 4 °C. To understand mechanisms of ECA transport, we quantified the transscleral transport of a fluorescent tracer, sodium fluorescein (NaF), that has a similar molecular weight but is more hydrophilic compared to ECA. Furthermore, we developed a mathematical model to simulate the transport processes and used it to analyze the experimental data. The model was also used to investigate the dependence of diffusion coefficients on volume fraction of viable cells and the binding of NaF and ECA to scleral tissues. Results The diffusion coefficients of ECA and NaF in the sclera were 48.5±15.1x10-7 cm2/s (n=9) and 5.23±1.93x10-7 cm2/s (n=8), respectively. Both diffusion coefficients were insensitive to cell shrinkage caused by ECA during the diffusion experiments and cell damage caused by the storage of tissues ex vivo before the experiments. Binding of ECA to scleral tissues could not be detected. The apparent maximum binding capacity and the apparent equilibrium dissociation constant for NaF were 80±5 mM and 2.5±0.5 mM (n=3), respectively. Conclusions These data demonstrated that ECA diffusion was minimally hindered by structures in the sclera, presumably due to the lack of cells and binding sites for ECA in the sclera. PMID:17356511

Computational characterization of lightweight multilayer MXene Li-ion battery anodes

NASA Astrophysics Data System (ADS)

Ashton, Michael; Hennig, Richard G.; Sinnott, Susan B.

2016-01-01

MXenes, a class of two-dimensional transition metal carbides and nitrides, have shown promise experimentally and computationally for use in energy storage applications. In particular, the most lightweight members of the monolayer MXene family (M = Sc, Ti, V, or Cr) are predicted to have gravimetric capacities above 400 mAh/g, higher than graphite. Additionally, intercalation of ions into multilayer MXenes can be accomplished at low voltages, and low diffusion barriers exist for Li diffusing across monolayer MXenes. However, large discrepancies have been observed between the calculated and experimental reversible capacities of MXenes. Here, dispersion-corrected density functional theory calculations are employed to predict reversible capacities and other battery-related properties for six of the most promising members of the MXene family (O-functionalized Ti- and V-based carbide MXenes) as bilayer structures. The calculated reversible capacities of the V2CO2 and Ti2CO2 bilayers agree more closely with experiment than do previous calculations for monolayers. Additionally, the minimum energy paths and corresponding energy barriers along the in-plane [1000] and [0100] directions for Li travelling between neighboring MXene layers are determined. V4C3O2 exhibits the lowest diffusion barrier of the compositions considered, at 0.42 eV, but its reversible capacity (148 mAh/g) is dragged down by its heavy formula unit. Conversely, the V2CO2 MXene shows good reversible capacity (276 mAh/g), but a high diffusion barrier (0.82 eV). We show that the diffusion barriers of all bilayer structures are significantly higher than those calculated for the corresponding monolayers, advocating the use of dispersed monolayer MXenes instead of multilayers in high performance anodes.

Soot Volume Fraction Maps for Normal and Reduced Gravity Laminar Acetylene Jet Diffusion Flames

NASA Technical Reports Server (NTRS)

Greenberg, Paul S.; Ku, Jerry C.

1997-01-01

The study of soot particulate distribution inside gas jet diffusion flames is important to the understanding of fundamental soot particle and thermal radiative transport processes, as well as providing findings relevant to spacecraft fire safety, soot emissions, and radiant heat loads for combustors used in air-breathing propulsion systems. Compared to those under normal gravity (1-g) conditions, the elimination of buoyancy-induced flows is expected to significantly change the flow field in microgravity (O g) flames, resulting in taller and wider flames with longer particle residence times. Work by Bahadori and Edelman demonstrate many previously unreported qualitative and semi-quantitative results, including flame shape and radiation, for sooting laminar zas jet diffusion flames. Work by Ku et al. report soot aggregate size and morphology analyses and data and model predictions of soot volume fraction maps for various gas jet diffusion flames. In this study, we present the first 1-g and 0-g comparisons of soot volume fraction maps for laminar acetylene and nitrogen-diluted acetylene jet diffusion flames. Volume fraction is one of the most useful properties in the study of sooting diffusion flames. The amount of radiation heat transfer depends directly on the volume fraction and this parameter can be measured from line-of-sight extinction measurements. Although most Soot aggregates are submicron in size, the primary particles (20 to 50 nm in diameter) are in the Rayleigh limit, so the extinction absorption) cross section of aggregates can be accurately approximated by the Rayleigh solution as a function of incident wavelength, particles' complex refractive index, and particles' volume fraction.

Atom-Level Understanding of the Sodiation Process in Silicon Anode Material.

PubMed

Jung, Sung Chul; Jung, Dae Soo; Choi, Jang Wook; Han, Young-Kyu

2014-04-03

Despite the exceptionally large capacities in Li ion batteries, Si has been considered inappropriate for applications in Na ion batteries. We report an atomic-level study on the applicability of a Si anode in Na ion batteries using ab initio molecular dynamics simulations. While crystalline Si is not suitable for alloying with Na atoms, amorphous Si can accommodate 0.76 Na atoms per Si atom, corresponding to a specific capacity of 725 mA h g(-1). Bader charge analyses reveal that the sodiation of an amorphous Si electrode continues until before the local Na-rich clusters containing neutral Na atoms are formed. The amorphous Na0.76Si phase undergoes a volume expansion of 114% and shows a Na diffusivity of 7 × 10(-10) cm(2) s(-1) at room temperature. Overall, the amorphous Si phase turns out quite attractive in performance compared to other alloy-type anode materials. This work suggests that amorphous Si might be a competitive candidate for Na ion battery anodes.

Self-assembly of novel hierarchical flowers-like Sn3O4 decorated on 2D graphene nanosheets hybrid as high-performance anode materials for LIBs

NASA Astrophysics Data System (ADS)

Chen, Xuefang; Huang, Ying; Li, Tianpeng; Wei, Chao; Yan, Jing; Feng, Xuansheng

2017-05-01

Novel hierarchical flower-like Sn3O4 assembled by thin Sn3O4 nanosheets, as a kind of mixed-valence tin oxide, decorated on two-dimensional graphene nanosheets has been synthesized via a hydrothermal route and a step solution deoxidization technique. More importantly, as the anode materials for lithium ion batteries, the flower-like Sn3O4/graphene composite has not been investigated in detail. Noticeably, the nanosheets stemming from flower-like Sn3O4 and graphene have been linked together to form a specials three dimensional structure, possessing high active surface area and large enough inner spaces, which is benefit to the diffusion of liquid electrolyte into the electrode materials. In addition, the special structure could provide sufficient free volume to buffer the volume expansion appeared in the process of discharging and charging. The as-prepared flowers-like Sn3O4/graphene displayed excellent electrochemical performance with high capacity and good cycling stability as anode materials for lithium ion batteries. The discharge capacity is 1727 mAh/g in the first cycle at the current density of 60 mA/g. The obtained reversible capacity is 631mAh/g with a coulomb efficiency of 97.04% after 50 cycles. With its better electrochemical properties, the as-prepared flowers-like Sn3O4/graphene has the potential to be the next generation materials as an environmentally benign, abundant, cheap anode materials for lithium ion batteries.

Diffusion of multiple species with excluded-volume effects.

PubMed

Bruna, Maria; Chapman, S Jonathan

2012-11-28

Stochastic models of diffusion with excluded-volume effects are used to model many biological and physical systems at a discrete level. The average properties of the population may be described by a continuum model based on partial differential equations. In this paper we consider multiple interacting subpopulations/species and study how the inter-species competition emerges at the population level. Each individual is described as a finite-size hard core interacting particle undergoing brownian motion. The link between the discrete stochastic equations of motion and the continuum model is considered systematically using the method of matched asymptotic expansions. The system for two species leads to a nonlinear cross-diffusion system for each subpopulation, which captures the enhancement of the effective diffusion rate due to excluded-volume interactions between particles of the same species, and the diminishment due to particles of the other species. This model can explain two alternative notions of the diffusion coefficient that are often confounded, namely collective diffusion and self-diffusion. Simulations of the discrete system show good agreement with the analytic results.

Major diffusion leaks of clamp-on leaf cuvettes still unaccounted: how erroneous are the estimates of Farquhar et al. model parameters?

PubMed

Rodeghiero, Mirco; Niinemets, Ulo; Cescatti, Alessandro

2007-08-01

Estimates of leaf gas-exchange characteristics using standard clamp-on leaf chambers are prone to errors because of diffusion leaks. While some consideration has been given to CO(2) diffusion leaks, potential water vapour diffusion leaks through chamber gaskets have been neglected. We estimated diffusion leaks of two clamp-on Li-Cor LI-6400 (Li-Cor, Inc., Lincoln, NE, USA) leaf chambers with polymer foam gaskets and enclosing either 2 or 6 cm(2) leaf area, and conducted a sensitivity analysis of the diffusion leak effects on Farquhar et al. photosynthesis model parameters - the maximum carboxylase activity of ribulose 1 x 5-bisphosphate carboxylase/oxygenase (Rubisco) (V(cmax)), capacity for photosynthetic electron transport (J(max)) and non-photorespiratory respiration rate in light (R(d)). In addition, net assimilation rate (A(n)) versus intercellular CO(2) (C(i)) responses were measured in leaves of Mediterranean evergreen species Quercus ilex L. enclosing the whole leaf chamber in a polyvinyl fluoride bag flushed with the exhaust air of leaf chamber, thereby effectively reducing the CO(2) and water vapour gradients between ambient air and leaf chamber. For the empty chambers, average diffusion leak for CO(2), K(CO2), (molar flow rate corresponding to unit CO(2) mole fraction difference) was ca. 0.40 micromol s(-1). K(CO2) increased ca. 50% if a dead leaf was clamped between the leaf chamber. Average diffusion leak for H(2)O was ca. 5- to 10-fold larger than the diffusion leak for CO(2). Sensitivity analyses demonstrated that the consequence of a CO(2) diffusion leak was apparent enhancement of A(n) at high CO(2) mole fraction and reduction at lower CO(2) mole fraction, and overall compression of C(i) range. As the result of these modifications, Farquhar et al. model parameters were overestimated. The degree of overestimation increased in the order of V(cmax) < J(max) < R(d), and was larger for smaller chambers and for leaves with lower photosynthetic capacity, leading to overestimation of all three parameters by 70-290% for 2 cm(2), and by 10-60% for 6 cm(2) chamber. Significant diffusion corrections (5-36%) were even required for leaves with high photosynthetic capacity measured in largest chamber. Water vapour diffusion leaks further enhanced the overestimation of model parameters. For small chambers and low photosynthetic capacities, apparent C(i) was simulated to decrease with increasing A(n) because of simultaneous CO(2) and H(2)O diffusion leaks. Measurements in low photosynthetic capacity Quercus ilex leaves enclosed in 2 cm(2) leaf chamber exhibited negative apparent C(i) values at highest A(n). For the same leaves measured with the entire leaf chamber enclosed in the polyvinyl fluoride bag, C(i) and A(n) increased monotonically. While the measurements without the bag could be corrected for diffusion leaks, the required correction in A(n) and transpiration rates was 100-500%, and there was large uncertainty in Farquhar et al. model parameters derived from 'corrected'A(n)/C(i) response curves because of uncertainties in true diffusion leaks. These data demonstrate that both CO(2) and water vapour diffusion leaks need consideration in measurements with clamp-on leaf cuvettes. As plants in natural environments are often characterized by low photosynthetic capacities, cuvette designs need to be improved for reliable measurements in such species.

Modeling adsorption: Investigating adsorbate and adsorbent properties

NASA Astrophysics Data System (ADS)

Webster, Charles Edwin

1999-12-01

Surface catalyzed reactions play a major role in current chemical production technology. Currently, 90% of all chemicals are produced by heterogeneously catalyzed reactions. Most of these catalyzed reactions involve adsorption, concentrating the substrate(s) (the adsorbate) on the surface of the solid (the adsorbent). Pore volumes, accessible surface areas, and the thermodynamics of adsorption are essential in the understanding of solid surface characteristics fundamental to catalyst and adsorbent screening and selection. Molecular properties such as molecular volumes and projected molecular areas are needed in order to convert moles adsorbed to surface volumes and areas. Generally, these molecular properties have been estimated from bulk properties, but many assumptions are required. As a result, different literature values are employed for these essential molecular properties. Calculated molar volumes and excluded molecular areas are determined and tabulated for a variety of molecules. Molecular dimensions of molecules are important in the understanding of molecular exclusion as well as size and shape selectivity, diffusion, and adsorbent selection. Molecular dimensions can also be used in the determination of the effective catalytic pore size of a catalyst. Adsorption isotherms, on zeolites, (crystalline mineral oxides) and amorphous solids, can be analyzed with the Multiple Equilibrium Analysis (MEA) description of adsorption. The MEA produces equilibrium constants (Ki), capacities (ni), and thermodynamic parameters (enthalpies, ΔHi, and entropies, ΔSi) of adsorption for each process. Pore volumes and accessible surface areas are calculated from the process capacities. Adsorption isotherms can also be predicted for existing and new adsorbate-adsorbent systems with the MEA. The results show that MEA has the potential of becoming a standard characterization method for microporous solids that will lead to an increased understanding of their behavior in gas adsorption and catalysis. These studies are also applicable to environmental cleanup applications, such as waste stream purification and separation procedures as well as decontamination of chemical warfare agents.

Comparison of usual interstitial pneumonia and nonspecific interstitial pneumonia: quantification of disease severity and discrimination between two diseases on HRCT using a texture-based automated system.

PubMed

Park, Sang Ok; Seo, Joon Beom; Kim, Namkug; Lee, Young Kyung; Lee, Jeongjin; Kim, Dong Soon

2011-01-01

To evaluate the usefulness of an automated system for quantification and discrimination of usual interstitial pneumonia (UIP) and nonspecific interstitial pneumonia (NSIP). An automated system to quantify six regional high-resolution CT (HRCT) patterns: normal, NL; ground-glass opacity, GGO; reticular opacity, RO; honeycombing, HC; emphysema, EMPH; and consolidation, CONS, was developed using texture and shape features. Fifty-four patients with pathologically proven UIP (n = 26) and pathologically proven NSIP (n = 28) were included as part of this study. Inter-observer agreement in measuring the extent of each HRCT pattern between the system and two thoracic radiologists were assessed in 26 randomly selected subsets using an interclass correlation coefficient (ICC). A linear regression analysis was used to assess the contribution of each disease pattern to the pulmonary function test parameters. The discriminating capacity of the system between UIP and NSIP was evaluated using a binomial logistic regression. The overall ICC showed acceptable agreement among the system and the two radiologists (r = 0.895 for the abnormal lung volume fraction, 0.706 for the fibrosis fraction, 0.895 for NL, 0.625 for GGO, 0.626 for RO, 0.893 for HC, 0.800 for EMPH, and 0.430 for CONS). The volumes of NL, GGO, RO, and EMPH contribute to forced expiratory volume during one second (FEV₁) (r = 0.72, β values, 0.84, 0.34, 0.34 and 0.24, respectively) and forced vital capacity (FVC) (r = 0.76, β values, 0.82, 0.28, 0.21 and 0.34, respectively). For diffusing capacity (DL(co)), the volumes of NL and HC were independent contributors in opposite directions (r = 0.65, β values, 0.64, -0.21, respectively). The automated system can help discriminate between UIP and NSIP with an accuracy of 82%. The automated quantification system of regional HRCT patterns can be useful in the assessment of disease severity and may provide reliable agreement with the radiologists' results. In addition, this system may be useful in differentiating between UIP and NSIP.

A framework to analyze cerebral mean diffusivity using surface guided diffusion mapping in diffusion tensor imaging

PubMed Central

Kwon, Oh-Hun; Park, Hyunjin; Seo, Sang-Won; Na, Duk L.; Lee, Jong-Min

2015-01-01

The mean diffusivity (MD) value has been used to describe microstructural properties in Diffusion Tensor Imaging (DTI) in cortical gray matter (GM). Recently, researchers have applied a cortical surface generated from the T1-weighted volume. When the DTI data are analyzed using the cortical surface, it is important to assign an accurate MD value from the volume space to the vertex of the cortical surface, considering the anatomical correspondence between the DTI and the T1-weighted image. Previous studies usually sampled the MD value using the nearest-neighbor (NN) method or Linear method, even though there are geometric distortions in diffusion-weighted volumes. Here we introduce a Surface Guided Diffusion Mapping (SGDM) method to compensate for such geometric distortions. We compared our SGDM method with results using NN and Linear methods by investigating differences in the sampled MD value. We also projected the tissue classification results of non-diffusion-weighted volumes to the cortical midsurface. The CSF probability values provided by the SGDM method were lower than those produced by the NN and Linear methods. The MD values provided by the NN and Linear methods were significantly greater than those of the SGDM method in regions suffering from geometric distortion. These results indicate that the NN and Linear methods assigned the MD value in the CSF region to the cortical midsurface (GM region). Our results suggest that the SGDM method is an effective way to correct such mapping errors. PMID:26236180

Exercise-induced oxyhaemoglobin desaturation, ventilatory limitation and lung diffusing capacity in women during and after exercise.

PubMed

Walls, Justin; Maskrey, Michael; Wood-Baker, Richard; Stedman, Wade

2002-06-01

Arterial haemoglobin saturation during exercise in healthy young women [eight subjects mean (SEM) age 20.8 (1.8) years] was measured to confirm the theory that young women experience exercise-induced arterial hypoxaemia (EIAH) at a lower relative percentage of maximal oxygen uptake (VO(2max)) than has been documented in their male counterparts. To determine if flow limitation [the percentage of the tidal volume ( V(T)) that met or exceeded the boundary established by multiple maximal expiratory manoeuvres] and/or post-exercise lung diffusing capacity are linked to EIAH in women, and to investigate the influence of exercise intensity and duration on post-exercise carbon monoxide lung diffusing capacity ( D(L, CO)), these parameters were measured during and after three exercise tests (incremental test until exhaustion, 5 km run and 5 km run with sprint). All subjects experienced physiologically significant EIAH (a fall of more than 3% in oxygen saturation of arterial blood from levels at rest) and seven subjects experienced flow limitation during the VO(2max) protocol [mean (SD) 12.2 (8.8)% of V(T)]. Even though there was no significant relationship between aerobic capacity and the degree of flow limitation ( r=0.33, P>0.05), the flow limitation was related to absolute ventilation in the subjects studied ( r=0.82, P<0.05). There was no significant relationship between decrements in post exercise D(L, CO) and EIAH ( r=0.05, P>0.05), however there was a strong correlation between the extent of flow limitation (% of V(T)) and EIAH ( r=0.71). Significant decreases in D(L, CO) lasted for up to 16 h after each of the exercise tests ( P<0.05) and lasted for a further 8 h after the maximal test ( P<0.05). Exercise intensity was the main contributing factor to the observed decreases in post-exercise D(L, CO) with the percentage of VO(2max) attained during the various tests being significantly related to the fall in D(L, CO) for 1, 2, 3, 16 and 24 h after exercise ( P<0.05). As the appearance of flow limitation closely coincided with the appearance of EIAH, the results from the present study suggest that flow limitation is a contributing factor to EIAH in women although the exact mechanism remains unclear.

Pulmonary function levels as predictors of mortality in a national sample of US adults.

PubMed

Neas, L M; Schwartz, J

1998-06-01

Single breath pulmonary diffusing capacity for carbon monoxide (DL(CO)) was examined as a predictor of all-cause mortality among 4,333 subjects who were aged 25-74 years at baseline in the First National Health and Nutrition Examination Survey (NHANES I) conducted from 1971 to 1975. The relation of the percentage of predicted DL(CO) to all-cause mortality was examined in a Cox proportional hazard model that included age, sex, race, current smoking status, systolic blood pressure, serum cholesterol, alcohol consumption, body mass index, percentage of predicted forced vital capacity (FVC), and the ratio of forced expiratory volume at 1 second (FEV1) to FVC. Mortality had a linear association with the percentage of predicted FVC (rate ratio (RR) = 1.12, 95% confidence interval (CI) 1.08-1.17, for a 10% decrement) and a significantly nonlinear association with the percentage of predicted DL(CO) with an adverse effect that was clearly evident for levels below 85% of those predicted (RR = 1.24, 95% CI 1.12-1.37 for a 10% decrement). The relative hazard for the percentage of predicted DL(CO) below 85% was not modified by sex, smoking status, or exclusion of subjects with clinical respiratory disease on the initial examination. This association with the percentage of predicted DL(CO) was present among 3,005 subjects with FEV1 levels above 90% of those predicted. Thus, pulmonary diffusing capacity below 85% of predicted levels is a significant predictor of the all-cause mortality rate within the general US population independent of standard spirometry measures and even in the absence of apparent clinical respiratory disease.

Sorption of water by biochar: Closer look at micropores

NASA Astrophysics Data System (ADS)

Spokas, Kurt; Hall, Kathleen; Joseph, Stephan; Kammann, Claudia; Novak, Jeffrey; Gámiz, Beatriz; Cox, Lucia

2017-04-01

Typically, biochar has been assumed to increase total water content of the soil system and thereby positively influence plant-soil moisture hydraulics. In this work, we focused on water's interaction with micro-pores (<2 nm) and its influence on water availability. In other words, the main question was if the driving force of water's behavior was the physics or chemistry of biochar pores. The temporal scale of liquid water entry into biochar's pore network is very complex, with observed bubbling occurring days, weeks, and even months after a piece of biochar is immersed under water at ambient conditions. Elevated temperature biochar typically has a positive heat of immersion measured calorimetrically, whereas the calculated BET energy of sorption from a water sorption isotherm typically decrease with production temperatures. To further complicate matters, different pieces of biochar interact differently with water even though the entire batch was created in the same reactor at the same time and after liquid water exposure the physical structure of biochar is irreversibly altered, sometimes negligible other times catastrophically. Nevertheless, based on the estimations of diffusion coefficients in biochar from drying curve analyses, pore surface moieties do reduce the effective diffusivity of water vapor in biochar. Contrary to the rule of thumb in soil physics, where higher gas filled porosity correlates with higher soil moisture holding capacities, our results indicate that biochar's water sorption rate and capacity is actually reduced at ambient conditions by an increase in microporous volume. Thereby, biochar's hydrophobic behavior is partly due to the entrapment of gas within the air-filled porosity which prevents liquid water's entry, even though these biochars possess elevated gas phase sorption capacities (e.g., BET N2/CO2 surface areas).

Self-diffusion of Si and O in diopside-anorthite melt at high pressures

NASA Astrophysics Data System (ADS)

Tinker, David; Lesher, Charles E.; Hutcheon, Ian D.

2003-01-01

Self-diffusion coefficients for Si and O in Di 58An 42 liquid were measured from 1 to 4 GPa and temperatures from 1510 to 1764°C. Glass starting powders enriched in 18O and 28Si were mated to isotopically normal glass powders to form simple diffusion couples, and self-diffusion experiments were conducted in the piston cylinder device (1 and 2 GPa) and in the multianvil apparatus (3.5 and 4 GPa). Profiles of 18O/ 16O and 29,30Si/ 28Si were measured using secondary ion mass spectrometry. Self-diffusion coefficients for O (D(O)) are slightly greater than self-diffusion coefficients for Si (D(Si)) and are often the same within error. For example, D(O) = 4.20 ± 0.42 × 10 -11 m 2/s and D(Si) = 3.65 ± 0.37 × 10 -11 m 2/s at 1 GPa and 1662°C. Activation energies for self-diffusion are 215 ± 13 kJ/mol for O and 227 ± 13 kJ/mol for Si. Activation volumes for self-diffusion are -2.1 ± 0.4 cm 3/mol and -2.3 ± 0.4 cm 3/mol for O and Si, respectively. The similar self-diffusion coefficients for Si and O, similar activation energies, and small, negative activation volumes are consistent with Si and O transport by a cooperative diffusion mechanism, most likely involving the formation and disassociation of a high-coordinated intermediate species. The small absolute magnitudes of the activation volumes imply that Di 58An 42 liquid is close to a transition from negative to positive activation volume, and Adam-Gibbs theory suggests that this transition is linked to the existence of a critical fraction (˜0.6) of bridging oxygen.

Adsorption characteristics of trace levels of bromate in drinking water by modified bamboo-based activated carbons.

PubMed

Chen, Ho-Wen; Chuang, Yen Hsun; Hsu, Cheng-Feng; Huang, Winn-Jung

2017-09-19

This study was undertaken to investigate the adsorption kinetics and isotherms of bromate (BrO 3 - ) on bamboo charcoals that are activated with nitrogen and water vapor. Bamboo-based activated carbon (AC) was dipped in acid and oxidized in a mixture of potassium permanganate and sulfuric acid. Oxidation treatment considerably improved the physicochemical properties of AC, including purity, pore structure and surface nature, significantly enhancing BrO 3 - adsorption capacity. AC with many oxygenated groups and a high mesopore volume exhibited a particularly favorable tendency for BrO 3 - adsorption. Its adsorption of BrO 3 - is best fitted using Langmuir isotherm, and forms a monolayer. A kinetic investigation revealed that the adsorption of BrO 3 - by the ACs involved chemical sorption and was controlled by intra-particle diffusion. The competitive effects of natural organic matter (NOM) on AC were evaluated, and found to reduce the capacity of carbon to adsorb BrO 3 - . Residual dissolved ozone reacted with AC, reducing its capacity to absorb BrO 3 - . Proper dosing and staging of the ozonation processes can balance the ozone treatment efficiency, BrO 3 - formation, and the subsequent removal of BrO 3 - .

Breathing pattern and breathlessness in idiopathic pulmonary fibrosis: An observational study.

PubMed

Olukogbon, Kasope L; Thomas, Paul; Colasanti, Ricardo; Hope-Gill, Ben; Williams, Edgar Mark

2016-02-01

Idiopathic pulmonary fibrosis (IPF) is characterized by progressive decline in lung function and increasing dyspnoea. The aim of this study was to investigate the relationship among IPF, pulmonary function, resting tidal breathing patterns and level of breathlessness. Thirty-one participants with IPF and 17 matched healthy controls underwent lung function testing, followed by a 2-min period of resting tidal breathing. The IPF cohort was stratified according to disease severity, based on their forced vital capacity and diffusion capacity for carbon monoxide. In comparison to the healthy controls, the IPF cohort showed a higher tidal volume, VT , of 0.22 L (P = 0.026) and a raised minute ventilation in the severest IPF group, while no differences in the timing of inspiration or expiration were observed. In the IPF cohort, the ratio of VT to forced vital capacity was around 15% higher. These changes corresponded with an increase in the self-reported sensation of breathlessness. Those with IPF increased their depth of breathing with worsening disease severity, with IPF-induced changes in pulmonary function and breathlessness associated with an altered tidal breathing pattern. © 2015 Asian Pacific Society of Respirology.

Cobalt oxide-carbon nanosheet nanoarchitecture as an anode for high-performance lithium-ion battery.

PubMed

Wang, Huanlei; Mao, Nan; Shi, Jing; Wang, Qigang; Yu, Wenhua; Wang, Xin

2015-02-04

To improve the electrochemical performance of cobalt oxide owing to its inherent poor electrical conductivity and large volume expansion/contraction, Co3O4-carbon nanosheet hybrid nanoarchitectures were synthesized by a facile and scalable chemical process. However, it is still a challenge to control the size of Co3O4 particles down to ∼5 nm. Herein, we created nanosized cobalt oxide anchored 3D arrays of carbon nanosheets by the control of calcination condition. The uniformly dispersed Co3O4 nanocrystals on carbon nanosheets held a diameter down to ∼5 nm. When tested as anode materials for lithium-ion batteries, high lithium storage over 1200 mAh g(-1) is achieved, whereas high rate capability with capacity of about 390 mAh g(-1) at 10 A g(-1) is maintained through nanoscale diffusion distances and interconnected porous structure. After 500 cycles, the cobalt oxide-carbon nansheets hybrid display a reversible capacity of about 970 mAh g(-1) at 1 A g(-1). The synergistic effect between nanosized cobalt oxide and sheetlike interconnected carbon nanosheets lead to the greatly improved specific capacity and the initial Coulombic efficiency of the hybrids.

Rapid adsorption of 2,4-dichlorophenoxyacetic acid by iron oxide nanoparticles-doped carboxylic ordered mesoporous carbon.

PubMed

Tang, Lin; Zhang, Sheng; Zeng, Guang-Ming; Zhang, Yi; Yang, Gui-De; Chen, Jun; Wang, Jing-Jing; Wang, Jia-Jia; Zhou, Yao-Yu; Deng, Yao-Cheng

2015-05-01

The ordered mesoporous carbon composite functionalized with carboxylate groups and iron oxide nanoparticles (Fe/OMC) was successfully prepared and used to adsorb 2,4-dichlorophenoxyacetic acid (2,4-D) from wastewater. The resultant adsorbent possessed high degree of order, large specific surface area and pore volume, and good magnetic properties. The increase in initial pollutant concentration and contact time would make the adsorption capacity increase, but the pH and temperature are inversely proportional to 2,4-D uptake. The equilibrium of adsorption was reached within 120 min, and the equilibrated adsorption capacity increased from 99.38 to 310.78 mg/g with the increase of initial concentration of 2,4-D from 100 to 500 mg/L. Notablely, the adsorption capacity reached 97% of the maximum within the first 5 min. The kinetics and isotherm study showed that the pseudo-second-order kinetic and Langmuir isotherm models could well fit the adsorption data. These results indicate that Fe/OMC has a good potential for the rapid adsorption of 2,4-D and prevention of its further diffusion. Copyright © 2014 Elsevier Inc. All rights reserved.

Automated Quantitative Computed Tomography Versus Visual Computed Tomography Scoring in Idiopathic Pulmonary Fibrosis: Validation Against Pulmonary Function.

PubMed

Jacob, Joseph; Bartholmai, Brian J; Rajagopalan, Srinivasan; Kokosi, Maria; Nair, Arjun; Karwoski, Ronald; Raghunath, Sushravya M; Walsh, Simon L F; Wells, Athol U; Hansell, David M

2016-09-01

The aim of the study was to determine whether a novel computed tomography (CT) postprocessing software technique (CALIPER) is superior to visual CT scoring as judged by functional correlations in idiopathic pulmonary fibrosis (IPF). A total of 283 consecutive patients with IPF had CT parenchymal patterns evaluated quantitatively with CALIPER and by visual scoring. These 2 techniques were evaluated against: forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), diffusing capacity for carbon monoxide (DLco), carbon monoxide transfer coefficient (Kco), and a composite physiological index (CPI), with regard to extent of interstitial lung disease (ILD), extent of emphysema, and pulmonary vascular abnormalities. CALIPER-derived estimates of ILD extent demonstrated stronger univariate correlations than visual scores for most pulmonary function tests (PFTs): (FEV1: CALIPER R=0.29, visual R=0.18; FVC: CALIPER R=0.41, visual R=0.27; DLco: CALIPER R=0.31, visual R=0.35; CPI: CALIPER R=0.48, visual R=0.44). Correlations between CT measures of emphysema extent and PFTs were weak and did not differ significantly between CALIPER and visual scoring. Intriguingly, the pulmonary vessel volume provided similar correlations to total ILD extent scored by CALIPER for FVC, DLco, and CPI (FVC: R=0.45; DLco: R=0.34; CPI: R=0.53). CALIPER was superior to visual scoring as validated by functional correlations with PFTs. The pulmonary vessel volume, a novel CALIPER CT parameter with no visual scoring equivalent, has the potential to be a CT feature in the assessment of patients with IPF and requires further exploration.

Diffusion in silicate melts: III. Empirical models for multicomponent diffusion

NASA Astrophysics Data System (ADS)

Yan, Liang; Richter, Frank M.; Chamberlin, Laurinda

1997-12-01

Empirical models for multicomponent diffusion in an isotropic fluid were derived by splitting the component's dispersion velocity into two parts: (a) an intrinsic velocity which is proportional to each component's electrochemical potential gradient and independent of reference frame and (b) a net interaction velocity which is both model and reference frame dependent. Simple molecules (e.g., M pO q) were chosen as endmember components. The interaction velocity is assumed to be either the same for each component (leading to a common relaxation velocity U) or proportional to a common interaction force ( F). U or F is constrained by requiring no local buildup in either volume or charge. The most general form of the model-derived diffusion matrix [ D] can be written as a product of a model-dependent kinetic matrix [ L] and a model independent thermodynamic matrix [ G], [ D] = [ L] · [ G]. The elements of [ G] are functions of derivatives of chemical potential with respect to concentration. The elements of [ L] are functions of concentration and partial molar volume of the endmember components, Cio and Vio, and self diffusivity Di, and charge number zi of individual diffusing species. When component n is taken as the dependent variable they can be written in a common form L ij = D jδ ij + C io[V noD n - V joD j)A i + (p nz nD n - p jz jD j)B i] where the functional forms of the scaling factors Ai and Bi depend on the model considered. The off-diagonal element Lij ( i ≠ j) is directly proportional to the concentration of component i, and thus negligible when i is a dilute component. The salient feature of kinetic interaction or relaxation is to slow down larger (volume or charge) and faster diffusing components and to speed up smaller (volume or charge) and slower moving species, in order to prevent local volume or charge buildup. Empirical models for multicomponent diffusion were tested in the ternary system CaOAl 2O 3SiO 2 at 1500°C and 1 GPa over a large range of melt compositions. Model-derived diffusion matrices calculated using measured self diffusivities (Ca, Al, Si, and O), partial molar volumes, and activities were compared with experimentally derived diffusion matrices at two melt compositions. Chemical diffusion profiles computed using the model-derived diffusion matrices, accounting for the compositional dependency of self diffusivities and activity coefficients, were also compared with the experimentally measured ones. Good agreement was found between the ionic common-force model derived diffusion profiles and the experimentally measured ones. Secondary misfits could result from either inadequacies of the model or inaccuracies in activity-composition relationship. The results show that both kinetic interactions and thermodynamic nonideality contribute significantly to the observed diffusive coupling in the molten CaOAl 2O 3SiO 2.

Chronic Hypoxia Accentuates Dysanaptic Lung Growth.

PubMed

Llapur, Conrado J; Martínez, Myriam R; Grassino, Pedro T; Stok, Ana; Altieri, Héctor H; Bonilla, Federico; Caram, María M; Krowchuk, Natasha M; Kirby, Miranda; Coxson, Harvey O; Tepper, Robert S

2016-08-01

Adults born and raised at high altitudes have larger lung volumes and greater pulmonary diffusion capacity compared with adults at low altitude; however, it remains unclear whether the air and tissue volumes have comparable increases and whether there is a difference in airway size. To assess the effect of chronic hypoxia on lung growth using in vivo high-resolution computed tomography measurements. Healthy adults born and raised at moderate altitude (2,000 m above sea level; n = 19) and at low altitude (400 m above sea level; n = 23) underwent high-resolution computed tomography. Differences in total lung, air, and tissue volume, mean lung density, as well as airway lumen and wall areas in anatomically matched airways were compared between groups. No significant differences for age, sex, weight, or height were found between the two groups (P > 0.05). In a multivariate regression model, altitude was a significant contributor for total lung volume (P = 0.02), air volume (P = 0.03), and tissue volume (P = 0.03), whereby the volumes were greater for the moderate- versus the low-altitude group. However, altitude was not a significant contributor for mean lung density (P = 0.35) or lumen and wall areas in anatomically matched segmental, subsegmental, and subsubsegmental airways. Our findings suggest that the adult lung did not increase lung volume later in life by expansion of an existing number of alveoli, but rather from increased alveolarization early in life. In addition, chronic hypoxia accentuates dysanaptic lung growth by increasing the lung parenchyma but not the airways.

A novel finite volume discretization method for advection-diffusion systems on stretched meshes

NASA Astrophysics Data System (ADS)

Merrick, D. G.; Malan, A. G.; van Rooyen, J. A.

2018-06-01

This work is concerned with spatial advection and diffusion discretization technology within the field of Computational Fluid Dynamics (CFD). In this context, a novel method is proposed, which is dubbed the Enhanced Taylor Advection-Diffusion (ETAD) scheme. The model equation employed for design of the scheme is the scalar advection-diffusion equation, the industrial application being incompressible laminar and turbulent flow. Developed to be implementable into finite volume codes, ETAD places specific emphasis on improving accuracy on stretched structured and unstructured meshes while considering both advection and diffusion aspects in a holistic manner. A vertex-centered structured and unstructured finite volume scheme is used, and only data available on either side of the volume face is employed. This includes the addition of a so-called mesh stretching metric. Additionally, non-linear blending with the existing NVSF scheme was performed in the interest of robustness and stability, particularly on equispaced meshes. The developed scheme is assessed in terms of accuracy - this is done analytically and numerically, via comparison to upwind methods which include the popular QUICK and CUI techniques. Numerical tests involved the 1D scalar advection-diffusion equation, a 2D lid driven cavity and turbulent flow case. Significant improvements in accuracy were achieved, with L2 error reductions of up to 75%.

Imaging Effects of Neurotrophic Factor Genes on Brain Plasticity and Repair in Multiple Sclerosis

DTIC Science & Technology

2010-07-01

cortical thickness and subcortical volume measures, lesion volumetry , and voxel-based morphometry and diffusion imaging. We are continuing to...th ickness and subcortical volume measures, lesion volumetry , and voxel-based morphometry and diffusion imaging. Regressio n and symbolic modeling

Thermal Property Measurement of Semiconductor Melt using Modified Laser Flash Method

NASA Technical Reports Server (NTRS)

Lin, Bochuan; Zhu, Shen; Ban, Heng; Li, Chao; Scripa, Rosalla N.; Su, Ching-Hua; Lehoczky, Sandor L.

2003-01-01

This study further developed standard laser flash method to measure multiple thermal properties of semiconductor melts. The modified method can determine thermal diffusivity, thermal conductivity, and specific heat capacity of the melt simultaneously. The transient heat transfer process in the melt and its quartz container was numerically studied in detail. A fitting procedure based on numerical simulation results and the least root-mean-square error fitting to the experimental data was used to extract the values of specific heat capacity, thermal conductivity and thermal diffusivity. This modified method is a step forward from the standard laser flash method, which is usually used to measure thermal diffusivity of solids. The result for tellurium (Te) at 873 K: specific heat capacity 300.2 Joules per kilogram K, thermal conductivity 3.50 Watts per meter K, thermal diffusivity 2.04 x 10(exp -6) square meters per second, are within the range reported in literature. The uncertainty analysis showed the quantitative effect of sample geometry, transient temperature measured, and the energy of the laser pulse.

Zeolite-Templated Mesoporous Silicon Particles for Advanced Lithium-Ion Battery Anodes.

PubMed

Kim, Nahyeon; Park, Hyejeong; Yoon, Naeun; Lee, Jung Kyoo

2018-04-24

For the practical use of high-capacity silicon anodes in high-energy lithium-based batteries, key issues arising from the large volume change of silicon during cycling must be addressed by the facile structural design of silicon. Herein, we discuss the zeolite-templated magnesiothermic reduction synthesis of mesoporous silicon (mpSi) (mpSi-Y, -B, and -Z derived from commercial zeolite Y, Beta, and ZSM-5, respectively) microparticles having large pore volume (0.4-0.5 cm 3 /g), wide open pore size (19-31 nm), and small primary silicon particles (20-35 nm). With these appealing mpSi particle structural features, a series of mpSi/C composites exhibit outstanding performance including excellent cycling stabilities for 500 cycles, high specific and volumetric capacities (1100-1700 mAh g -1 and 640-1000 mAh cm -3 at 100 mA g -1 ), high Coulombic efficiencies (approximately 100%), and remarkable rate capabilities, whereas conventional silicon nanoparticles (SiNP)/C demonstrate limited cycle life. These enhanced electrochemical responses of mpSi/C composites are further manifested by low impedance build-up, high Li ion diffusion rate, and small electrode thickness changes after cycling compared with those of SiNP/C composite. In addition to the outstanding electrochemical properties, the low-cost materials and high-yield processing make the mpSi/C composites attractive candidates for high-performance and high-energy Li-ion battery anodes.

Microsized Porous SiOx@C Composites Synthesized through Aluminothermic Reduction from Rice Husks and Used as Anode for Lithium-Ion Batteries.

PubMed

Cui, Jinlong; Cui, Yongfu; Li, Shaohui; Sun, Hongliang; Wen, Zhongsheng; Sun, Juncai

2016-11-09

Microsized porous SiO x @C composites used as anode for lithium-ion batteries (LIBs) are synthesized from rice husks (RHs) through low-temperature (700 °C) aluminothermic reduction. The resulting SiO x @C composite shows mesoporous irregular particle morphology with a high specific surface area of 597.06 m 2 /g under the optimized reduction time. This porous SiO x @C composite is constructed by SiO x nanoparticles uniformly dispersed in the C matrix. When tested as anode material for LIBs, it displays considerable specific capacity (1230 mAh/g at a current density of 0.1 A/g) and excellent cyclic stability with capacity fading of less than 0.5% after 200 cycles at 0.8 A/g. The dramatic volume change for the Si anode during lithium-ion (Li + ) insertion and extraction can be successfully buffered because of the formation of Li 2 O and Li 4 SiO 4 during initial lithiation process and carbon coating layer on the surface of SiO x . The porous structure could also mitigate the volume change and mechanical strains and shorten the Li + diffusion path length. These characteristics improve the cyclic stability of the electrode. This low-cost and environment-friendly SiO x @C composite anode material exhibits great potential as an alternative for traditional graphite anodes.

Expanding the calculation of activation volumes: Self-diffusion in liquid water

NASA Astrophysics Data System (ADS)

Piskulich, Zeke A.; Mesele, Oluwaseun O.; Thompson, Ward H.

2018-04-01

A general method for calculating the dependence of dynamical time scales on macroscopic thermodynamic variables from a single set of simulations is presented. The approach is applied to the pressure dependence of the self-diffusion coefficient of liquid water as a particularly useful illustration. It is shown how the activation volume associated with diffusion can be obtained directly from simulations at a single pressure, avoiding approximations that are typically invoked.

Regional Microstructural and Volumetric Magnetic Resonance Imaging (MRI) Abnormalities in the Corpus Callosum of Neonates With Congenital Heart Defect Undergoing Cardiac Surgery.

PubMed

Hagmann, Cornelia; Singer, Jitka; Latal, Beatrice; Knirsch, Walter; Makki, Malek

2016-03-01

The purpose of the study is to investigate the structural development of the corpus callosum in term neonates with congenital heart defect before and after surgery using diffusion tensor imaging and 3-dimensional T1-weighted magnetic resonance imaging (MRI). We compared parallel and radial diffusions, apparent diffusion coefficient (ADC), fractional anisotropy, and volume of 5 substructures of the corpus callosum: genu, rostral body, body, isthmus, and splenium. Compared to healthy controls, we found a significantly lower volume of the splenium and total corpus callosum and a higher radial diffusion and lower fractional anisotropy in the splenium of patients presurgery; a lower volume in all substructures in the postsurgery group; higher radial diffusion in the rostral body, body, and splenium; and a higher apparent diffusion coefficient in the splenium of postsurgery patients. Similar fractional anisotropy changes in congenital heart defect patients were reported in preterm infants. Our findings in apparent diffusion coefficient in the splenium of these patients (pre and postsurgery) are comparable to findings in preterm neonates with psychomotor delay. Delayed maturation of the isthmus was also reported in preterm infants. © The Author(s) 2015.

Developmental plasticity and stability in the tracheal networks supplying Drosophila flight muscle in response to rearing oxygen level.

PubMed

Harrison, Jon F; Waters, James S; Biddulph, Taylor A; Kovacevic, Aleksandra; Klok, C Jaco; Socha, John J

2018-04-01

While it is clear that the insect tracheal system can respond in a compensatory manner to both hypoxia and hyperoxia, there is substantial variation in how different parts of the system respond. However, the response of tracheal structures, from the tracheoles to the largest tracheal trunks, have not been studied within one species. In this study, we examined the effect of larval/pupal rearing in hypoxia, normoxia, and hyperoxia (10, 21 or 40kPa oxygen) on body size and the tracheal supply to the flight muscles of Drosophila melanogaster, using synchrotron radiation micro-computed tomography (SR-µCT) to assess flight muscle volumes and the major tracheal trunks, and confocal microscopy to assess the tracheoles. Hypoxic rearing decreased thorax length whereas hyperoxic-rearing decreased flight muscle volumes, suggestive of negative effects of both extremes. Tomography at the broad organismal scale revealed no evidence for enlargement of the major tracheae in response to lower rearing oxygen levels, although tracheal size scaled with muscle volume. However, using confocal imaging, we found a strong inverse relationship between tracheole density within the flight muscles and rearing oxygen level, and shorter tracheolar branch lengths in hypoxic-reared animals. Although prior studies of larger tracheae in other insects indicate that axial diffusing capacity should be constant with sequential generations of branching, this pattern was not found in the fine tracheolar networks, perhaps due to the increasing importance of radial diffusion in this regime. Overall, D. melanogaster responded to rearing oxygen level with compensatory morphological changes in the small tracheae and tracheoles, but retained stability in most of the other structural components of the tracheal supply to the flight muscles. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chemical and Temperature Effects on Diffusion in a Model Polymer/Nanoparticle Composite

NASA Astrophysics Data System (ADS)

Janes, Dustin; Durning, Christopher

Polymers and inks used in medical devices may be strengthened with nanoparticle fillers, so an understanding of how they may affect the release of residuals and additives via diffusion will help modernize biocompatibility testing. Transport of small molecules in polymers with increasing volume fraction of impermeable nanoparticles is often poorly predicted by the simple Maxwell model for heterogeneous media. In this presentation we will examine two diffusant classes, only one of which possesses hydrogen bonding interactions with the nanoparticle surface. Since similar reductions in mutual diffusion coefficients were observed in both cases we attribute the enhancement of the ''blocking effect'' in nanocomposites to a reduction in polymer mobility in the interfacial volume near the nanoparticle. The temperature and penetrant concentration dependence of the diffusion coefficients were examined in the context of a Vrentas-Duda free volume model that includes a thermally activated prefactor. While data obtained for rubbery poly(methyl acrylate) clearly obeys the expected Arrhenius scaling with EA = 11 kJ/mol, results for films containing d = 14 nm spherical silica nanoparticles do not, providing more evidence that polymer free volume is perturbed in unexpected ways even for conceptually simple systems. National Science Foundation IGERT Program, Pall Corporation.

The entrance of water into beef and dog red cells.

PubMed

VILLEGAS, R; BARTON, T C; SOLOMON, A K

1958-11-20

The rate constants for diffusion of THO across the red cell membrane of beef and dog, and the rate of entrance of water into the erythrocytes of these species under an osmotic pressure gradient have been measured. For water entrance into the erythrocyte by diffusion the rate constants are 0.10 +/- 0.02 msec.(-1) (beef) and 0.14 +/- 0.03 msec.(-1) (dog); the permeability coefficients for water entrance under a pressure gradient of 1 osmol./cm(3) are 0.28 See PDF for Equation These values permit the calculation of an equivalent pore radius for the erythrocyte membrane of 4.1 A for beef and 7.4 A for dog. In the beef red cell the change in THO diffusion due to osmotically produced cell volume shifts has been studied. The resistance to THO diffusion increases as the cell volume increases. At the maximum volume, (1.06 times normal), THO diffusion is decreased to 0.84 times the normal rate. This change in diffusion is attributed to swelling of the cellular membrane.

Diffusion and perfusion weighted magnetic resonance imaging for tumor volume definition in radiotherapy of brain tumors.

PubMed

Guo, Lu; Wang, Gang; Feng, Yuanming; Yu, Tonggang; Guo, Yu; Bai, Xu; Ye, Zhaoxiang

2016-09-21

Accurate target volume delineation is crucial for the radiotherapy of tumors. Diffusion and perfusion magnetic resonance imaging (MRI) can provide functional information about brain tumors, and they are able to detect tumor volume and physiological changes beyond the lesions shown on conventional MRI. This review examines recent studies that utilized diffusion and perfusion MRI for tumor volume definition in radiotherapy of brain tumors, and it presents the opportunities and challenges in the integration of multimodal functional MRI into clinical practice. The results indicate that specialized and robust post-processing algorithms and tools are needed for the precise alignment of targets on the images, and comprehensive validations with more clinical data are important for the improvement of the correlation between histopathologic results and MRI parameter images.

Microscopic diffusion and hydrodynamic interactions of hemoglobin in red blood cells.

PubMed

Doster, Wolfgang; Longeville, Stéphane

2007-08-15

The cytoplasm of red blood cells is congested with the oxygen storage protein hemoglobin occupying a quarter of the cell volume. The high protein concentration leads to a reduced mobility; the self-diffusion coefficient of hemoglobin in blood cells is six times lower than in dilute solution. This effect is generally assigned to excluded volume effects in crowded media. However, the collective or gradient diffusion coefficient of hemoglobin is only weakly dependent on concentration, suggesting the compensation of osmotic and friction forces. This would exclude hydrodynamic interactions, which are of dynamic origin and do not contribute to the osmotic pressure. Hydrodynamic coupling between protein molecules is dominant at short time- and length scales before direct interactions are fully established. Employing neutron spin-echo-spectroscopy, we study hemoglobin diffusion on a nanosecond timescale and protein displacements on the scale of a few nanometers. A time- and wave-vector dependent diffusion coefficient is found, suggesting the crossover of self- and collective diffusion. Moreover, a wave-vector dependent friction function is derived, which is a characteristic feature of hydrodynamic interactions. The wave-vector and concentration dependence of the long-time self-diffusion coefficient of hemoglobin agree qualitatively with theoretical results on hydrodynamics in hard spheres suspensions. Quantitative agreement requires us to adjust the volume fraction by including part of the hydration shell: Proteins exhibit a larger surface/volume ratio compared to standard colloids of much larger size. It is concluded that hydrodynamic and not direct interactions dominate long-range molecular transport at high concentration.

Imaging Effects of Neurotrophic Factor Genes on Brain Plasticity and Repair in Multiple Sclerosis

DTIC Science & Technology

2011-07-01

focal and diffuse effects in brain (including cortical thickness and subcortical volume measures, lesion volumetry , and voxel-based morphometry and...to both focal and diffuse effects in gray and white matter, including cortical thickness and subcortical volume measures, lesion volumetry , and

Diffusion and related transport mechanisms in brain tissue

NASA Astrophysics Data System (ADS)

Nicholson, Charles

2001-07-01

Diffusion plays a crucial role in brain function. The spaces between cells can be likened to the water phase of a foam and many substances move within this complicated region. Diffusion in this interstitial space can be accurately modelled with appropriate modifications of classical equations and quantified from measurements based on novel micro-techniques. Besides delivering glucose and oxygen from the vascular system to brain cells, diffusion also moves informational substances between cells, a process known as volume transmission. Deviations from expected results reveal how local uptake, degradation or bulk flow may modify the transport of molecules. Diffusion is also essential to many therapies that deliver drugs to the brain. The diffusion-generated concentration distributions of well-chosen molecules also reveal the structure of brain tissue. This structure is represented by the volume fraction (void space) and the tortuosity (hindrance to diffusion imposed by local boundaries or local viscosity). Analysis of these parameters also reveals how the local geometry of the brain changes with time or under pathological conditions. Theoretical and experimental approaches borrow from classical diffusion theory and from porous media concepts. Earlier studies were based on radiotracers but the recent methods use a point-source paradigm coupled with micro-sensors or optical imaging of macromolecules labelled with fluorescent tags. These concepts and methods are likely to be applicable elsewhere to measure diffusion properties in very small volumes of highly structured but delicate material.

Pulmonary Function Testing After Stereotactic Body Radiotherapy to the Lung

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bishawi, Muath; Kim, Bong; Moore, William H.

2012-01-01

Purpose: Surgical resection remains the standard of care for operable early-stage non-small-cell lung cancer (NSCLC). However, some patients are not fit for surgery because of comorbidites such as chronic obstructive pulmonary disease (COPD) and other medical conditions. We aimed to evaluate pulmonary function and tumor volume before and after stereotactic body radiotherapy (SBRT) for patients with and without COPD in early-stage lung cancer. Methods and Materials: A review of prospectively collected data of Stage I and II lung cancers, all treated with SBRT, was performed. The total SBRT treatment was 60 Gy administered in three 20 Gy fractions. The patientsmore » were analyzed based on their COPD status, using their pretreatment pulmonary function test cutoffs as established by the American Thoracic Society guidelines (forced expiratory volume [FEV]% {<=}50% predicted, FEV%/forced vital capacity [FVC]% {<=}70%). Changes in tumor volume were also assessed by computed tomography. Results: Of a total of 30 patients with Stage I and II lung cancer, there were 7 patients in the COPD group (4 men, 3 women), and 23 in t he No-COPD group (9 men, 14 women). At a mean follow-up time of 4 months, for the COPD and No-COPD patients, pretreatment and posttreatment FEV% was similar: 39 {+-} 5 vs. 40 {+-} 9 (p = 0.4) and 77 {+-} 0.5 vs. 73 {+-} 24 (p = 0.9), respectively. The diffusing capacity of the lungs for carbon monoxide (DL{sub CO}) did significantly increase for the No-COPD group after SBRT treatment: 60 {+-} 24 vs. 69 {+-} 22 (p = 0.022); however, DL{sub CO} was unchanged for the COPD group: 49 {+-} 13 vs. 50 {+-} 14 (p = 0.8). Although pretreatment tumor volume was comparable for both groups, tumor volume significantly shrank in the No-COPD group from 19 {+-} 24 to 9 {+-} 16 (p < 0.001), and there was a trend in the COPD patients from 12 {+-} 9 to 6 {+-} 5 (p = 0.06). Conclusion: SBRT did not seem to have an effect on FEV{sub 1} and FVC, but it shrank tumor volume and improved DL{sub CO} for patients without COPD.« less

Diffusion anisotropy in fresh and fixed prostate tissue ex vivo.

PubMed

Bourne, Roger M; Bongers, Andre; Chatterjee, Aritrick; Sved, Paul; Watson, Geoffrey

2016-08-01

To investigate diffusion anisotropy in whole human prostate specimens Seven whole radical prostatectomy specimens were obtained with informed patient consent and institutional ethics approval. Diffusion tensor imaging was performed at 9.4 Tesla. Diffusion tensors were calculated from the native acquired data and after progressive downsampling Fractional anisotropy (FA) decreased as voxel volume increased, and differed widely between prostates. Fixation decreased mean FA by ∼0.05-0.08 at all voxel volumes but did not alter principle eigenvector orientation. In unfixed tissue high FA (> 0.6) was found only in voxels of volume <0.5 mm(3) , and then only in a small fraction of all voxels. At typical clinical voxel volumes (4-16 mm(3) ) less than 50% of voxels had FA > 0.25. FA decreased at longer diffusion times (Δ = 60 or 80 ms compared with 20 ms), but only by ∼0.02 at typical clinical voxel volume. Peripheral zone FA was significantly lower than transition zone FA in five of the seven prostates FA varies widely between prostates. The very small proportion of clinical size voxels with high FA suggests that in clinical DWI studies ADC based on three-direction measurements will be minimally affected by anisotropy. Magn Reson Med 76:626-634, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Ischemic lesion volume determination on diffusion weighted images vs. apparent diffusion coefficient maps.

PubMed

Bråtane, Bernt Tore; Bastan, Birgul; Fisher, Marc; Bouley, James; Henninger, Nils

2009-07-07

Though diffusion weighted imaging (DWI) is frequently used for identifying the ischemic lesion in focal cerebral ischemia, the understanding of spatiotemporal evolution patterns observed with different analysis methods remains imprecise. DWI and calculated apparent diffusion coefficient (ADC) maps were serially obtained in rat stroke models (MCAO): permanent, 90 min, and 180 min temporary MCAO. Lesion volumes were analyzed in a blinded and randomized manner by 2 investigators using (i) a previously validated ADC threshold, (ii) visual determination of hypointense regions on ADC maps, and (iii) visual determination of hyperintense regions on DWI. Lesion volumes were correlated with 24 hour 2,3,5-triphenyltetrazoliumchloride (TTC)-derived infarct volumes. TTC-derived infarct volumes were not significantly different from the ADC and DWI-derived lesion volumes at the last imaging time points except for significantly smaller DWI lesions in the pMCAO model (p=0.02). Volumetric calculation based on TTC-derived infarct also correlated significantly stronger to volumetric calculation based on last imaging time point derived lesions on ADC maps than DWI (p<0.05). Following reperfusion, lesion volumes on the ADC maps significantly reduced but no change was observed on DWI. Visually determined lesion volumes on ADC maps and DWI by both investigators correlated significantly with threshold-derived lesion volumes on ADC maps with the former method demonstrating a stronger correlation. There was also a better interrater agreement for ADC map analysis than for DWI analysis. Ischemic lesion determination by ADC was more accurate in final infarct prediction, rater independent, and provided exclusive information on ischemic lesion reversibility.

Apatite U-Pb thermochronolgy applied to complex geological settings - insights from geo/thermochronology and geochemistry

NASA Astrophysics Data System (ADS)

Paul, Andre; Spikings, Richard; Ulyanov, Alexey; Chew, David

2016-04-01

Application of high temperature (>350oC) thermochronology is limited to the U-Pb system of accessory minerals, such as apatite, under the assumption that radiogenic lead is lost to thermally activated volume diffusion into an infinite reservoir. Cochrane et al. (2015) have demonstrated a working example from the northern Andes of South America. Predictions from volume diffusion theory were compared with measured single grain U-Pb date correlated to shortest diffusion radius and in-situ profiles measured by LA-ICP-MS. Results from both techniques were found to be in agreement with predictions from thermally activated, volume diffusion. However, outliers from the ID-TIMS data suggested some complexity, as grains were found to be too young relative to their diffusion radius. Interaction of multiple processes can be responsible for the alteration of apatite U-Pb dates such as: (1) metamorphic (over)growth, (2) fluid aided alteration/recrystallization and (3) metamictization and fracturing of the grain. Further, predictions from volume diffusion rely on the input parameters: (a) diffusivity, (b) activation energy and (c) shortest diffusion radius. Diffusivity and activation energy are potentially influenced by the chemical composition and subsequent changes in crystal structure. Currently there is one value for diffusion parameter and activation energy established for (Durango) apatite (Cherniak et al., 1991). Correlation between diffusivity/activation energy and composition has not been established. We investigate if correlations exist between diffusivity/activation energy and composition by obtaining single grain apatite U-Pb date and chemical compostion and correlating these to their diffusion radius. We test the consistency of apatite closure temperature, by comparing the apatite U-Pb dates with lower temperature thermochronometers such as white mica and K-feldspar Ar/Ar and by petrographic observations. We test if chemical information can be a proxy to identify metamorphic (over)growth and fluid aided alteration/recrystallization. We seek to evaluate if apatite U-Pb thermochronology can be applied to a broad range of rock types and geological environments or if limitations must be drawn.

Three-dimensional hierarchical C-Co-N/Se derived from metal-organic framework as superior cathode for Li-Se batteries

NASA Astrophysics Data System (ADS)

He, Jiarui; Lv, Weiqiang; Chen, Yuanfu; Xiong, Jie; Wen, Kechun; Xu, Chen; Zhang, Wanli; Li, Yanrong; Qin, Wu; He, Weidong

2017-09-01

Three-dimensional, porous graphitic carbon co-doped with cobalt and nitrogen (C-Co-N) is prepared with metal-organic framework (MOF) and employed as Lewis base matrix to host selenium. Owing to the unique structure with abundant micro/meso-pores, the highly-conductive C-Co-N matrix provides highly-efficient channels for electron transfer and ionic diffusion, and sufficient surface area for loading of selenium nanoparticles while mitigating dissolution of polyselenides and suppressing volume expansion. The homogenous distribution of cobalt nanoparticles and nitrogen-group in C-Co-N composite immobilize polyselenides through strong chemical interaction in the operation of Li-Se batteries. With a very high Se loading of 76.5 wt%, the C-Co-N/Se cathode delivers superior electrochemical performance with an ultrahigh reversible capacity of 672.3 mAh g-1 (99.6% of the theoretical value) and a capacity of 574.2 mAh g-1 after 200 cycles, giving a capacity fading of only 0.07% per cycle and a nearly 100% Columbic efficiency. In-situ Raman spectroscopy and density functional theory simulations are employed to investigate the Se (de)lithiation mechanism at the electrolyte/cathode interface, and confirm that the structure and composition of C-Co-N scaffold give rise to efficient cathode host for high-performance Se-based cathodes with dramatically reduced capacity fading.

High-pressure-assisted design of porous topological semimetal carbon for Li-ion battery anode with high-rate performance

NASA Astrophysics Data System (ADS)

Liu, Junyi; Wang, Shuo; Qie, Yu; Zhang, Cunzhi; Sun, Qiang

2018-02-01

It has been a great challenge to develop a high-rate anode material with high-capacity, fast Li-ions diffusion and long cycling life going beyond the commercially used graphite in Li-ion battery. Here for the first time we propose a strategy combined high-pressure synthesis method with the global structure search to find a topological semimetal porous carbon as the desired anode. Our crystal-structure searching shows that we can obtain the ground state of an orthorhombic phase Li C6 with regular pores at 30 GPa, and when the Li atoms are removed, the resulting carbon structure is the recently predicted interlocked graphene network (IGN) that is a topological semimetal with an intrinsic high electronic conductivity. Based on the state-of-the-art first-principles calculations, we further find that the Li-ion migration energy barrier in the IGN is extremely low and the estimated diffusion coefficient can reach a magnitude of 10-4c m2/s at both low and high Li concentrations, which is three orders of magnitude larger than that of graphite anode. Moreover, the volume changes during the Li insertion and deinsertion are smaller than 3.2 % , while the theoretical specific capacity is the same as that of graphite anode. Our studies not only suggest a practical way of synthesizing the topological semimetal carbon but also propose a new anode material for Li-ion battery.

Magnetic resonance imaging evidence for presymptomatic change in thalamus and caudate in familial Alzheimer's disease.

PubMed

Ryan, Natalie S; Keihaninejad, Shiva; Shakespeare, Timothy J; Lehmann, Manja; Crutch, Sebastian J; Malone, Ian B; Thornton, John S; Mancini, Laura; Hyare, Harpreet; Yousry, Tarek; Ridgway, Gerard R; Zhang, Hui; Modat, Marc; Alexander, Daniel C; Rossor, Martin N; Ourselin, Sebastien; Fox, Nick C

2013-05-01

Amyloid imaging studies of presymptomatic familial Alzheimer's disease have revealed the striatum and thalamus to be the earliest sites of amyloid deposition. This study aimed to investigate whether there are associated volume and diffusivity changes in these subcortical structures during the presymptomatic and symptomatic stages of familial Alzheimer's disease. As the thalamus and striatum are involved in neural networks subserving complex cognitive and behavioural functions, we also examined the diffusion characteristics in connecting white matter tracts. A cohort of 20 presenilin 1 mutation carriers underwent volumetric and diffusion tensor magnetic resonance imaging, neuropsychological and clinical assessments; 10 were symptomatic, 10 were presymptomatic and on average 5.6 years younger than their expected age at onset; 20 healthy control subjects were also studied. We conducted region of interest analyses of volume and diffusivity changes in the thalamus, caudate, putamen and hippocampus and examined diffusion behaviour in the white matter tracts of interest (fornix, cingulum and corpus callosum). Voxel-based morphometry and tract-based spatial statistics were also used to provide unbiased whole-brain analyses of group differences in volume and diffusion indices, respectively. We found that reduced volumes of the left thalamus and bilateral caudate were evident at a presymptomatic stage, together with increased fractional anisotropy of bilateral thalamus and left caudate. Although no significant hippocampal volume loss was evident presymptomatically, reduced mean diffusivity was observed in the right hippocampus and reduced mean and axial diffusivity in the right cingulum. In contrast, symptomatic mutation carriers showed increased mean, axial and in particular radial diffusivity, with reduced fractional anisotropy, in all of the white matter tracts of interest. The symptomatic group also showed atrophy and increased mean diffusivity in all of the subcortical grey matter regions of interest, with increased fractional anisotropy in bilateral putamen. We propose that axonal injury may be an early event in presymptomatic Alzheimer's disease, causing an initial fall in axial and mean diffusivity, which then increases with loss of axonal density. The selective degeneration of long-coursing white matter tracts, with relative preservation of short interneurons, may account for the increase in fractional anisotropy that is seen in the thalamus and caudate presymptomatically. It may be owing to their dense connectivity that imaging changes are seen first in the thalamus and striatum, which then progress to involve other regions in a vulnerable neuronal network.

Granular activated carbon adsorption of MIB in the presence of dissolved organic matter.

PubMed

Summers, R Scott; Kim, Soo Myung; Shimabuku, Kyle; Chae, Seon-Ha; Corwin, Christopher J

2013-06-15

Based on the results of over twenty laboratory granular activated carbon (GAC) column runs, models were developed and utilized for the prediction of 2-methylisoborneol (MIB) breakthrough behavior at parts per trillion levels and verified with pilot-scale data. The influent MIB concentration was found not to impact the concentration normalized breakthrough. Increasing influent background dissolved organic matter (DOM) concentration was found to systematically decrease the GAC adsorption capacity for MIB. A series of empirical models were developed that related the throughput in bed volumes for a range of MIB breakthrough targets to the influent DOM concentration. The proportional diffusivity (PD) designed rapid small-scale column test (RSSCT) could be directly used to scale-up MIB breakthrough performance below 15% breakthrough. The empirical model to predict the throughput to 50% breakthrough based on the influent DOM concentration served as input to the pore diffusion model (PDM) and well-predicted the MIB breakthrough performance below a 50% breakthrough. The PDM predictions of throughput to 10% breakthrough well simulated the PD-RSSCT and pilot-scale 10% MIB breakthrough. Copyright © 2013 Elsevier Ltd. All rights reserved.

Imaging Effects of Neurotrophic Factor Genes on Brain Plasticity and Repair in Multiple Sclerosis

DTIC Science & Technology

2012-07-01

sensitive to focal and diffuse changes in brain tissue (including cortical thickness and subcortical volume measures, lesion volumetry , and voxel-based...sensitive to both focal and diffuse effects in gray and white matter, including cortical thickness and subcortical volume measures, lesion volumetry , and

Prevalence and features of advanced asbestosis (ILO profusion scores above 2/2). International Labour Office.

PubMed

Kilburn, K H

2000-01-01

In this study, the author addressed the following question: Do workers with advanced asbestosis have a restrictive pulmonary physiology, and, alternately, do those who have restrictive physiological tests have advanced asbestosis? One group was identified by obvious radiographic measurements, and the other group was defined via physiologic measurements. Total lung capacity, vital capacity, and flows were measured in 12,856 men exposed to asbestos, of whom 3,445 had radiographic signs of asbestosis, as defined by the International Labour Office criteria. Radiographically advanced asbestosis-International Labour Office criteria profusion greater than 2/2 was present in 85 (2.5%) of men. An additional 52 men had physiologically restrictive disease. The author, who compared pulmonary flows and volumes of these two groups, used mean percentage predicted, adjusted for height, age, and duration of cigarette smoking. Men with radiographically advanced asbestosis had normal total lung capacity (i.e., 105.5% predicted), reduced forced vital capacities (i.e., 82.7% predicted), air trapping (i.e., residual volume/total lung capacity increased to 54.4%), and reduced flows (i.e., forced expiratory flow [FEF25-75] = 60.6% predicted, forced expiratory volume in 1 s = 78.0% predicted, and forced expiratory volume in 1 s/forced vital capacity = 65.5%). In contrast, men selected from the same exposed population for restrictive disease (i.e., reduced total lung capacity [72.6% predicted] and forced vital capacity [61.5% predicted]) also had airflow obstruction (i.e., forced expiratory volume in 1 s/forced vital capacity of 74.5% predicted) and air trapping (i.e., residual volume/total lung capacity of 46.7%). Only half of these men had asbestosis--and it was of minimal severity. In summary, advanced asbestosis was characterized by airway obstruction and air trapping, both of which reduced vital capacity but not total lung capacity; therefore, it was not a restrictive disease. In contrast, restrictive disease was rare and was associated with minimal asbestosis.

Clinical, Bronchographic, Radiological, and Physiological Observations in Ten Cases of Asbestosis

PubMed Central

Leathart, G. L.

1960-01-01

Ten cases of asbestosis (eight male, two female), aged 45-65 years have been kept under observation for periods of up to eight years. Bronchiectasis was demonstrated bronchographically in six cases. Clubbing of the fingers and coarse crepitations appeared to be signs of bronchiectasis rather than of uncomplicated asbestosis. It is suggested that the prevalence of bronchiectasis is higher than has been reported previously because the patients survived longer. The radiological findings are tabulated and compared with previous descriptions. In these subjects there was no relationship between radiological and clinical state. Nine patients eventually showed clinical deterioration and it often proceeded rapidly. The radiograph however, usually remained unaltered. Pulmonary function tests, including diffusing capacity, arterial blood analysis and estimation of mechanical properties of the lung, were carried out in these 10 cases, and in 11 asbestos workers (aged 35-64 years) without radiological abnormality. The steady state diffusing capacity for carbon monoxide (Dco) at rest was lower in asbestosis than in the control subjects. The pulmonary compliance was remarkably low in asbestosis and related fairly closely to the vital capacity. The maximum voluntary ventilation was also low and was related to increased pulmonary resistance but it cannot be said whether this is in the airways or in the lung tissue. Indirect evidence of inequalities of ventilation/perfusion ratio was obtained in most cases. There is no convincing evidence that pulmonary fibrosis occurs without radiological abnormality, but a defect of diffusion may occur. There is no test of pulmonary function which is diagnostic, but a low pulmonary compliance, especially if combined with a low diffusing capacity, is confirmatory. It is suggested that the demonstration of a progressive decline in vital capacity, or in diffusing capacity, may enable a diagnosis of asbestosis to be made before radiological abnormality has appeared, but this point has not been proved.

Pulmonary Function Test Abnormalities in Children With Inflammatory Bowel Disease: Is It Common?

PubMed

El Amrousy, Doaa Mohamed; Hassan, Samir; El-Ashry, Heba; Yousef, Mohamed; Sharshar, Ragia

2018-04-03

The aim of the study was to evaluate the frequency and type of pulmonary dysfunction in newly diagnosed children with inflammatory bowel disease (IBD) and the correlation between pulmonary function tests (PFTs) and IBD activity. It is an observational case-control study. One hundred newly diagnosed children with IBD were enrolled as the patient group, which was subdivided into 52 with Crohn disease (CD) and 48 with ulcerative colitis (UC). Fifty healthy children matched for age, sex, height, and body mass index (BMI) served as the control group. PFTs in the form of forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), FEV1/FVC, residual volume (RV), total lung capacity (TLC), mid-forced expiratory flow of 25% to 75% (FEF 25%-75%) and diffusing capacity of the lung for carbon monoxide (DLCO) were evaluated in all studied children. PFTs were measured at diagnosis, every 6 months for a period of 3 years, during remission and at least once during activity in patient group. There was significant progressive deterioration in all PFTs in IBD patients compared with their PFTs at the start of the study (P < 0.05) except for FEV1/FVC, RV, and TLC (P > 0.05). There was significant deterioration during disease activity compared with remission state regarding FEV1, FVC, FEV 25% to 75%, and DLCO (P < 0.05). Significant negative correlation was found between disease activity in both UC and CD groups and FEV1, FVC, FEV 25% to 75%, and DLCO. Subclinical PFT abnormalities are common in pediatric IBD even during remission period. So, periodic PFT evaluation should be considered in the routine follow-up of IBD children.

Shannon Meets Fick on the Microfluidic Channel: Diffusion Limit to Sum Broadcast Capacity for Molecular Communication.

PubMed

Bicen, A Ozan; Lehtomaki, Janne J; Akyildiz, Ian F

2018-03-01

Molecular communication (MC) over a microfluidic channel with flow is investigated based on Shannon's channel capacity theorem and Fick's laws of diffusion. Specifically, the sum capacity for MC between a single transmitter and multiple receivers (broadcast MC) is studied. The transmitter communicates by using different types of signaling molecules with each receiver over the microfluidic channel. The transmitted molecules propagate through microfluidic channel until reaching the corresponding receiver. Although the use of different types of molecules provides orthogonal signaling, the sum broadcast capacity may not scale with the number of the receivers due to physics of the propagation (interplay between convection and diffusion based on distance). In this paper, the performance of broadcast MC on a microfluidic chip is characterized by studying the physical geometry of the microfluidic channel and leveraging the information theory. The convergence of the sum capacity for microfluidic broadcast channel is analytically investigated based on the physical system parameters with respect to the increasing number of molecular receivers. The analysis presented here can be useful to predict the achievable information rate in microfluidic interconnects for the biochemical computation and microfluidic multi-sample assays.

Reference database of lung volumes and capacities in wistar rats from 2 to 24 months.

PubMed

Filho, Wilson Jacob; Fontinele, Renata Gabriel; de Souza, Romeu Rodrigues

2014-01-01

This study determines the effects of growing and aging on lung physiological volumes and capacities and the incidence of inflammation in the small airways with age in rats. A reference database comprising of body weight gain, lung physiological volumes and capacities and an anatomopathological study of lung lesions over 240 Wistar rats from two to 24 -mo, is described. Tidal volume (TV), minute respiratory volume (MRV), and forced vital capacity (FVC) decreased during the first six months of life and then remain constant until 24 -mo of age. The respiratory frequency (Rf) and dynamical compliance (Cdyn) maintain at constant values from 2 to 24- mo of age; the functional residual capacity (FRC) increases in the first 6 -mo and then remains constant up to 24 -mo. It was verified a less intensive inflammation in the small airways with age, when compared with the median and large airways. This study showed the normal parameters for lung volumes and capacities and the incidence of infections for growing and aging male and female rats. The age-related data on these main respiratory parameters in rats would be useful in studies of aging-related disorders using this model and for safety pharmacology studies necessary for the development of drugs.

Reverse-Selective Diffusion in Nanocomposite Membranes

NASA Astrophysics Data System (ADS)

Hill, Reghan J.

2006-06-01

The permeability of certain polymer membranes with impenetrable nanoinclusions increases with the particle volume fraction [T. C. Merkel , Science 296, 519 (2002)SCIEAS0036-807510.1126/science.1069580]. The discovery contradicts qualitative expectations based on Maxwell’s classical theory of conduction or diffusion in composites with homogeneous phases. This Letter presents a theory based on an hypothesis that polymer chains are repelled from the inclusions during membrane casting. The accompanying increase in free volume, and hence solute diffusivity, yields bulk transport properties that are in good agreement with experiments.

Relation between heat of vaporization, ion transport, molar volume, and cation-anion binding energy for ionic liquids.

PubMed

Borodin, Oleg

2009-09-10

A number of correlations between heat of vaporization (H(vap)), cation-anion binding energy (E(+/-)), molar volume (V(m)), self-diffusion coefficient (D), and ionic conductivity for 29 ionic liquids have been investigated using molecular dynamics (MD) simulations that employed accurate and validated many-body polarizable force fields. A significant correlation between D and H(vap) has been found, while the best correlation was found for -log(DV(m)) vs H(vap) + 0.28E(+/-). A combination of enthalpy of vaporization and a fraction of the cation-anion binding energy was suggested as a measure of the effective cohesive energy for ionic liquids. A deviation of some ILs from the reported master curve is explained based upon ion packing and proposed diffusion pathways. No general correlations were found between the ion diffusion coefficient and molecular volume or the diffusion coefficient and cation/anion binding energy.

Increasing the Accuracy of Volume and ADC Delineation for Heterogeneous Tumor on Diffusion-Weighted MRI: Correlation with PET/CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gong, Nan-Jie; Wong, Chun-Sing, E-mail: drcswong@gmail.com; Chu, Yiu-Ching

2013-10-01

Purpose: To improve the accuracy of volume and apparent diffusion coefficient (ADC) measurements in diffusion-weighted magnetic resonance imaging (MRI), we proposed a method based on thresholding both the b0 images and the ADC maps. Methods and Materials: In 21 heterogeneous lesions from patients with metastatic gastrointestinal stromal tumors (GIST), gross lesion were manually contoured, and corresponding volumes and ADCs were denoted as gross tumor volume (GTV) and gross ADC (ADC{sub g}), respectively. Using a k-means clustering algorithm, the probable high-cellularity tumor tissues were selected based on b0 images and ADC maps. ADC and volume of the tissues selected using themore » proposed method were denoted as thresholded ADC (ADC{sub thr}) and high-cellularity tumor volume (HCTV), respectively. The metabolic tumor volume (MTV) in positron emission tomography (PET)/computed tomography (CT) was measured using 40% maximum standard uptake value (SUV{sub max}) as the lower threshold, and corresponding mean SUV (SUV{sub mean}) was also measured. Results: HCTV had excellent concordance with MTV according to Pearson's correlation (r=0.984, P<.001) and linear regression (slope = 1.085, intercept = −4.731). In contrast, GTV overestimated the volume and differed significantly from MTV (P=.005). ADC{sub thr} correlated significantly and strongly with SUV{sub mean} (r=−0.807, P<.001) and SUV{sub max} (r=−0.843, P<.001); both were stronger than those of ADC{sub g}. Conclusions: The proposed lesion-adaptive semiautomatic method can help segment high-cellularity tissues that match hypermetabolic tissues in PET/CT and enables more accurate volume and ADC delineation on diffusion-weighted MR images of GIST.« less

Overall adsorption rate of metronidazole, dimetridazole and diatrizoate on activated carbons prepared from coffee residues and almond shells.

PubMed

Flores-Cano, J V; Sánchez-Polo, M; Messoud, J; Velo-Gala, I; Ocampo-Pérez, R; Rivera-Utrilla, J

2016-03-15

This study analyzed the overall adsorption rate of metronidazole, dimetridazole, and diatrizoate on activated carbons prepared from coffee residues and almond shells. It was also elucidated whether the overall adsorption rate was controlled by reaction on the adsorbent surface or by intraparticle diffusion. Experimental data of the pollutant concentration decay curves as a function of contact time were interpreted by kinetics (first- and second-order) and diffusion models, considering external mass transfer, surface and/or pore volume diffusion, and adsorption on an active site. The experimental data were better interpreted by a first-order than second-order kinetic model, and the first-order adsorption rate constant varied linearly with respect to the surface area and total pore volume of the adsorbents. According to the diffusion model, the overall adsorption rate is governed by intraparticle diffusion, and surface diffusion is the main mechanism controlling the intraparticle diffusion, representing >90% of total intraparticle diffusion. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of Shapes of Solute Molecules on Diffusion: A Study of Dependences on Solute Size, Solvent, and Temperature.

PubMed

Chan, T C; Li, H T; Li, K Y

2015-12-24

Diffusivities of basically linear, planar, and spherical solutes at infinite dilution in various solvents are studied to unravel the effects of solute shapes on diffusion. On the basis of the relationship between the reciprocal of diffusivity and the molecular volume of solute molecules with similar shape in a given solvent at constant temperature, the diffusivities of solutes of equal molecular volume but different shapes are evaluated and the effects due to different shapes of two equal-sized solute molecules on diffusion are determined. It is found that the effects are dependent on the size of the solute pairs studied. Evidence of the dependence of the solute-shape effects on solvent properties is also demonstrated and discussed. Here, some new diffusion data of aromatic compounds in methanol at different temperatures are reported. The result for methanol in this study indicates that the effects of solute shape on diffusivity are only weakly dependent on temperature.

Modified free volume theory of self-diffusion and molecular theory of shear viscosity of liquid carbon dioxide.

PubMed

Nasrabad, Afshin Eskandari; Laghaei, Rozita; Eu, Byung Chan

2005-04-28

In previous work on the density fluctuation theory of transport coefficients of liquids, it was necessary to use empirical self-diffusion coefficients to calculate the transport coefficients (e.g., shear viscosity of carbon dioxide). In this work, the necessity of empirical input of the self-diffusion coefficients in the calculation of shear viscosity is removed, and the theory is thus made a self-contained molecular theory of transport coefficients of liquids, albeit it contains an empirical parameter in the subcritical regime. The required self-diffusion coefficients of liquid carbon dioxide are calculated by using the modified free volume theory for which the generic van der Waals equation of state and Monte Carlo simulations are combined to accurately compute the mean free volume by means of statistical mechanics. They have been computed as a function of density along four different isotherms and isobars. A Lennard-Jones site-site interaction potential was used to model the molecular carbon dioxide interaction. The density and temperature dependence of the theoretical self-diffusion coefficients are shown to be in excellent agreement with experimental data when the minimum critical free volume is identified with the molecular volume. The self-diffusion coefficients thus computed are then used to compute the density and temperature dependence of the shear viscosity of liquid carbon dioxide by employing the density fluctuation theory formula for shear viscosity as reported in an earlier paper (J. Chem. Phys. 2000, 112, 7118). The theoretical shear viscosity is shown to be robust and yields excellent density and temperature dependence for carbon dioxide. The pair correlation function appearing in the theory has been computed by Monte Carlo simulations.

Relation of exercise capacity with lung volumes before and after 6-minute walk test in subjects with COPD.

PubMed

Wibmer, Thomas; Rüdiger, Stefan; Kropf-Sanchen, Cornelia; Stoiber, Kathrin M; Rottbauer, Wolfgang; Schumann, Christian

2014-11-01

There is growing evidence that exercise-induced variation in lung volumes is an important source of ventilatory limitation and is linked to exercise intolerance in COPD. The aim of this study was to compare the correlations of walk distance and lung volumes measured before and after a 6-min walk test (6MWT) in subjects with COPD. Forty-five subjects with stable COPD (mean pre-bronchodilator FEV1: 47 ± 18% predicted) underwent a 6MWT. Body plethysmography was performed immediately pre- and post-6MWT. Correlations were generally stronger between 6-min walk distance and post-6MWT lung volumes than between 6-min walk distance and pre-6MWT lung volumes, except for FEV1. These differences in Pearson correlation coefficients were significant for residual volume expressed as percent of total lung capacity (-0.67 vs -0.58, P = .043), percent of predicted residual volume expressed as percent of total lung capacity (-0.68 vs -0.59, P = .026), inspiratory vital capacity (0.65 vs 0.54, P = .019), percent of predicted inspiratory vital capacity (0.49 vs 0.38, P = .037), and percent of predicted functional residual capacity (-0.62 vs -0.47, P = .023). In subjects with stable COPD, lung volumes measured immediately after 6MWT are more closely related to exercise limitation than baseline lung volumes measured before 6MWT, except for FEV1. Therefore, pulmonary function testing immediately after exercise should be included in future studies on COPD for the assessment of exercise-induced ventilatory constraints to physical performance that cannot be adequately assessed from baseline pulmonary function testing at rest. Copyright © 2014 by Daedalus Enterprises.

Alveolar-Membrane Diffusing Capacity Limits Performance in Boston Marathon Qualifiers

PubMed Central

Lavin, Kaleen M.; Straub, Allison M.; Uhranowsky, Kathleen A.; Smoliga, James M.; Zavorsky, Gerald S.

2012-01-01

Purpose (1) to examine the relation between pulmonary diffusing capacity and marathon finishing time, and (2), to evaluate the accuracy of pulmonary diffusing capacity for nitric oxide (DLNO) in predicting marathon finishing time relative to that of pulmonary diffusing capacity for carbon monoxide (DLCO). Methods 28 runners [18 males, age = 37 (SD 9) years, body mass = 70 (13) kg, height = 173 (9) cm, percent body fat = 17 (7) %] completed a test battery consisting of measurement of DLNO and DLCO at rest, and a graded exercise test to determine running economy and aerobic capacity prior to the 2011 Steamtown Marathon (Scranton, PA). One to three weeks later, all runners completed the marathon (range: 2∶22:38 to 4∶48:55). Linear regressions determined the relation between finishing time and a variety of anthropometric characteristics, resting lung function variables, and exercise parameters. Results In runners meeting Boston Marathon qualification standards, 74% of the variance in marathon finishing time was accounted for by differences in DLNO relative to body surface area (BSA) (SEE = 11.8 min, p<0.01); however, the relation between DLNO or DLCO to finishing time was non-significant in the non-qualifiers (p = 0.14 to 0.46). Whereas both DLCO and DLNO were predictive of finishing time for all finishers, DLNO showed a stronger relation (r2 = 0.30, SEE = 33.4 min, p<0.01) compared to DLCO when considering BSA. Conclusion DLNO is a performance-limiting factor in only Boston qualifiers. This suggests that alveolar-capillary membrane conductance is a limitation to performance in faster marathoners. Additionally, DLNO/BSA predicts marathon finishing time and aerobic capacity more accurately than DLCO. PMID:22984520

Facile fabrication of 3D porous MnO@GS/CNT architecture as advanced anode materials for high-performance lithium-ion battery.

PubMed

Wang, Junyong; Deng, Qinglin; Li, Mengjiao; Wu, Cong; Jiang, Kai; Hu, Zhigao; Chu, Junhao

2018-08-03

To overcome inferior rate capability and cycle stability of MnO-based anode materials for lithium-ion batteries (LIBs), we reported a novel 3D porous MnO@GS/CNT composite, consisting of MnO nanoparticles homogeneously distributed on the conductive interconnected framework based on 2D graphene sheets (GS) and 1D carbon nanotubes (CNTs). The distinctive architecture offers highly interpenetrated network along with efficient porous channels for fast electron transfer and ionic diffusion as well as abundant stress buffer space to accommodate the volume expansion of the MnO nanoparticles. The MnO@GS/CNT anode exhibits an ultrahigh capacity of 1115 mAh g -1 at 0.2 A g -1 after 150 cycles and outstanding rate capacity of 306 mAh g -1 at 10.0 A g -1 . Moreover, a stable capacity of 405 mAh g -1 after 3200 cycles can still be achieved, even at a large current density of 5.0 A g -1 . When coupled with LiMn 2 O 4 (LMO) cathode, the LMO [Formula: see text] MnO@GS/CNT full cell characterizes an excellent cycling stability and rate capability, indicating the promising application of MnO@GS/CNT anode in the next-generation LIBs.

Dimethyl Methylphosphonate Adsorption Capacities and Desorption Energies on Ordered Mesoporous Carbons.

PubMed

Huynh, Kim; Holdren, Scott; Hu, Junkai; Wang, Luning; Zachariah, Michael R; Eichhorn, Bryan W

2017-11-22

In this study, we determine effective adsorption capacities and desorption energies for DMMP with highly ordered mesoporous carbons (OMCs), 1D cylindrical FDU-15, 3D hexagonal CMK-3, 3D bicontinuous CMK-8, and as a reference, microporous BPL carbon. After exposure to DMMP vapor at room temperature for approximately 70 and 800 h, the adsorption capacity of DMMP for each OMC was generally proportional to the total surface area and pore volume, respectively. Desorption energies of DMMP were determined using a model-free isoconversional method applied to thermogravimetric analysis (TGA) data. Our experiments determined that DMMP saturated carbon will desorb any weakly bound DMMP from pores >2.4 nm at room temperature, and no DMMP will adsorb into pores smaller than 0.5 nm. The calculated desorption energies for high surface coverages, 25% DMMP desorbed from pores ≤2.4 nm, are 68-74 kJ mol -1 , which is similar to the DMMP heat of vaporization (52 kJ mol -1 ). At lower surface coverages, 80% DMMP desorbed, the DMMP desorption energies from the OMCs are 95-103 kJ mol -1 . This is overall 20-30 kJ mol -1 higher in comparison to that of BPL carbon, due to the pore size and diffusion through different porous networks.

A Universal Strategy for Hollow Metal Oxide Nanoparticles Encapsulated into B/N Co-Doped Graphitic Nanotubes as High-Performance Lithium-Ion Battery Anodes.

PubMed

Tabassum, Hassina; Zou, Ruqiang; Mahmood, Asif; Liang, Zibin; Wang, Qingfei; Zhang, Hao; Gao, Song; Qu, Chong; Guo, Wenhan; Guo, Shaojun

2018-02-01

Yolk-shell nanostructures have received great attention for boosting the performance of lithium-ion batteries because of their obvious advantages in solving the problems associated with large volume change, low conductivity, and short diffusion path for Li + ion transport. A universal strategy for making hollow transition metal oxide (TMO) nanoparticles (NPs) encapsulated into B, N co-doped graphitic nanotubes (TMO@BNG (TMO = CoO, Ni 2 O 3 , Mn 3 O 4 ) through combining pyrolysis with an oxidation method is reported herein. The as-made TMO@BNG exhibits the TMO-dependent lithium-ion storage ability, in which CoO@BNG nanotubes exhibit highest lithium-ion storage capacity of 1554 mA h g -1 at the current density of 96 mA g -1 , good rate ability (410 mA h g -1 at 1.75 A g -1 ), and high stability (almost 96% storage capacity retention after 480 cycles). The present work highlights the importance of introducing hollow TMO NPs with thin wall into BNG with large surface area for boosting LIBs in the terms of storage capacity, rate capability, and cycling stability. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A critical test of bivelocity hydrodynamics for mixtures.

PubMed

Brenner, Howard

2010-10-21

The present paper provides direct noncircumstantial evidence in support of the existence of a diffuse flux of volume j(v) in mixtures. As such, it supersedes an earlier paper [H. Brenner, J. Chem. Phys. 132, 054106 (2010)], which offered only indirect circumstantial evidence in this regard. Given the relationship of the diffuse volume flux to the fluid's volume velocity, this finding adds additional credibility to the theory of bivelocity hydrodynamics for both gaseous and liquid continua, wherein the term bivelocity refers to the independence of the fluid's respective mass and volume velocities. Explicitly, the present work provides a new and unexpected linkage between a pair of diffuse fluxes entering into bivelocity mixture theory, fluxes that were previously regarded as constitutively independent, except possibly for their coupling arising as a consequence of Onsager reciprocity. In particular, for the case of a binary mixture undergoing an isobaric, isothermal, external force-free, molecular diffusion process we establish by purely macroscopic arguments-while subsequently confirming by purely molecular arguments-the validity of the ansatz j(v)=(v(1)-v(2))j(1) relating the diffuse volume flux j(v) to the diffuse mass fluxes j(1)(=-j(2)) of the two species and, jointly, their partial specific volumes v(1),v(2). Confirmation of that relation is based upon the use of linear irreversible thermodynamic principles to embed this ansatz in a broader context, and to subsequently establish the accord thereof with Shchavaliev's solution of the multicomponent Boltzmann equation for dilute gases [M. Sh. Shchavaliev, Fluid Dyn. 9, 96 (1974)]. Moreover, because the terms v(1), v(2), and j(1) appearing on the right-hand side of the ansatz are all conventional continuum fluid-mechanical terms (with j(1) given, for example, by Fick's law for thermodynamically ideal solutions), parity requires that j(v) appearing on the left-hand side of that relation also be a continuum term. Previously, diffuse volume fluxes, whether in mixtures or single-component fluids, were widely believed to be noncontinuum in nature, and hence of interest only to those primarily concerned with transport phenomena in rarefied gases. This demonstration of the continuum nature of bivelocity hydrodynamics suggests that the latter subject should be of general interest to all fluid mechanicians, even those with no special interest in mixtures.

Instantaneous formation of SiOx nanocomposite for high capacity lithium ion batteries by enhanced disproportionation reaction during plasma spray physical vapor deposition.

PubMed

Tashiro, Tohru; Dougakiuchi, Masashi; Kambara, Makoto

2016-01-01

Nanocomposite SiO x particles have been produced by a single step plasma spray physical vapor deposition (PS-PVD) through rapid condensation of SiO vapors and the subsequent disproportionation reaction. Core-shell nanoparticles, in which 15 nm crystalline Si is embedded within the amorphous SiO x matrix, form under typical PS-PVD conditions, while 10 nm amorphous particles are formed when processed with an increased degree of non-equilibrium effect. Addition of CH 4 promotes reduction in the oxygen content x of SiO x , and thereby increases the Si volume in a nanocomposite particle. As a result, core-shell nanoparticles with x  = 0.46 as anode exhibit increased initial efficiency and the capacity of lithium ion batteries while maintaining cyclability. Furthermore, it is revealed that the disproportionation reaction of SiO is promoted in nanosized particles attaining increased Si diffusivity by two orders of magnitude compared to that in bulk, which facilitates instantaneous composite nanoparticle formation during PS-PVD.

Instantaneous formation of SiOx nanocomposite for high capacity lithium ion batteries by enhanced disproportionation reaction during plasma spray physical vapor deposition

PubMed Central

Tashiro, Tohru; Dougakiuchi, Masashi; Kambara, Makoto

2016-01-01

Abstract Nanocomposite SiOx particles have been produced by a single step plasma spray physical vapor deposition (PS-PVD) through rapid condensation of SiO vapors and the subsequent disproportionation reaction. Core-shell nanoparticles, in which 15 nm crystalline Si is embedded within the amorphous SiOx matrix, form under typical PS-PVD conditions, while 10 nm amorphous particles are formed when processed with an increased degree of non-equilibrium effect. Addition of CH4 promotes reduction in the oxygen content x of SiOx, and thereby increases the Si volume in a nanocomposite particle. As a result, core-shell nanoparticles with x = 0.46 as anode exhibit increased initial efficiency and the capacity of lithium ion batteries while maintaining cyclability. Furthermore, it is revealed that the disproportionation reaction of SiO is promoted in nanosized particles attaining increased Si diffusivity by two orders of magnitude compared to that in bulk, which facilitates instantaneous composite nanoparticle formation during PS-PVD. PMID:27933114

Superior performance of nanoscaled Fe3O4 as anode material promoted by mosaicking into porous carbon framework

NASA Astrophysics Data System (ADS)

Wan, Wang; Wang, Chao; Zhang, Weidong; Chen, Jitao; Zhou, Henghui; Zhang, Xinxiang

2014-01-01

A nanoscale Fe3O4/porous carbon-multiwalled carbon nanotubes (MWCNTs) composite is synthesized through a simple hard-template method by using Fe2O3 nanoparticles as the precursor and SiO2 nanoparticles as the template. The composite shows good cycle performance (941 mAh g-1 for the first cycle at 0.1 C, with 106% capacity retention at the 80th cycle) and high rate capability (71% capacity retained at 5 C rate). Its excellent electrical properties can be attributed to the porous carbon framework structure, which is composed of carbon and MWCNTs. In this composite, the porous structure provides space for the change in Fe3O4 volume during cycling and shortens the lithium ion diffusion distance, the MWCNTs increase the electron conductivity, and the carbon coating reduces the risk of side reactions. The results provide clear evidences for the utility of porous carbon framework to improve the electrochemical performances of nanosized transition-metal oxides as anode materials for lithium-ion batteries.

Integrated Solid/Nanoporous Copper/Oxide Hybrid Bulk Electrodes for High-performance Lithium-Ion Batteries

PubMed Central

Hou, Chao; Lang, Xing-You; Han, Gao-Feng; Li, Ying-Qi; Zhao, Lei; Wen, Zi; Zhu, Yong-Fu; Zhao, Ming; Li, Jian-Chen; Lian, Jian-She; Jiang, Qing

2013-01-01

Nanoarchitectured electroactive materials can boost rates of Li insertion/extraction, showing genuine potential to increase power output of Li-ion batteries. However, electrodes assembled with low-dimensional nanostructured transition metal oxides by conventional approach suffer from dramatic reductions in energy capacities owing to sluggish ion and electron transport kinetics. Here we report that flexible bulk electrodes, made of three-dimensional bicontinuous nanoporous Cu/MnO2 hybrid and seamlessly integrated with Cu solid current collector, substantially optimizes Li storage behavior of the constituent MnO2. As a result of the unique integration of solid/nanoporous hybrid architecture that simultaneously enhances the electron transport of MnO2, facilitates fast ion diffusion and accommodates large volume changes on Li insertion/extraction of MnO2, the supported MnO2 exhibits a stable capacity of as high as ~1100 mA h g−1 for 1000 cycles, and ultrahigh charge/discharge rates. It makes the environmentally friendly and low-cost electrode as a promising anode for high-performance Li-ion battery applications. PMID:24096928

Adaptation of micro-diffusion method for the analysis of (15) N natural abundance of ammonium in samples with small volume.

PubMed

Zhang, Shasha; Fang, Yunting; Xi, Dan

2015-07-30

There are several preparation methods for the measurement of the nitrogen (N) isotopic composition of ammonium (NH4 (+) ) in different types of samples (freshwater, saltwater and soil extracts). The diffusion method is the most popular and it involves NH4 (+) in solutions being released under alkaline conditions and then immediately trapped by an acidified filter. However, the traditional preparation is designed for samples with large volume and relatively high N concentrations. The performance of diffusion for small-volume samples (e.g., a few milliliters) remains unknown. We examined the overall performance of micro-diffusion on 5 mL samples on varying the incubation time, temperature and initial NH4 (+) concentration. The trapped ammonia was chemically converted into nitrous oxide (N2 O) with hypobromite and hydroxylamine in sequence. The produced N2 O was analyzed by a commercially available purge and cryogenic trap system coupled to an isotope ratio mass spectrometer. We found that diffusion can be complete with no more than 7 days of treatment at 37 °C. Increasing the temperature to 50 °C and the incubation time to 11 days did not improve the overall performance. There were no significant differences in the overall performance during diffusion with NH4 (+) concentrations from 15 to 60 μM. The blank size was relatively large, and the N contamination might come from the reagents especially KCl salts. The method presented here combines micro-diffusion and hypobromite oxidation and hydroxylamine reduction. It is suitable for samples with small volume and low NH4 (+) concentrations. Our study demonstrates that the NH4 (+) concentrations in samples can be as low as 15 μM, and a volume of 5 mL is sufficient for this method. We suggest that this method can be used for the routine determination of (15) N/(14) N for either natural abundance or (15) N-enriched NH4 (+) . Copyright © 2015 John Wiley & Sons, Ltd.

Energetics of multicomponent diffusion in molten CaO-Al 2O 3-SiO 2

NASA Astrophysics Data System (ADS)

Liang, Yan; Davis, Andrew M.

2002-02-01

The energetics of multicomponent diffusion in molten CaO-Al2O3-SiO2 (CAS) were examined experimentally at 1440 to 1650°C and 0.5 to 2 GPa. Two melt compositions were investigated: a haplodacitic melt (25 wt.% CaO, 15% Al2O3, and 60% SiO2) and a haplobasaltic melt (35% CaO, 20% Al2O3, and 45% SiO2). Diffusion matrices were measured in a mass-fixed frame of reference with simple oxides as end-member components and Al2O3 as a dependent variable. Chemical diffusion in molten CAS shows clear evidence of diffusive coupling among the components. The diffusive flux of SiO2 is significantly enhanced whenever there is a large CaO gradient that is oriented in a direction opposite to the SiO2 gradient. This coupling effect is more pronounced in the haplodacitic melt and is likely to be significant in natural magmas of rhyolitic to andesitic compositions. The relative magnitude of coupled chemical diffusion is not very sensitive to changes in temperature and pressure. To a good approximation, the measured diffusion matrices follow well-defined Arrhenius relationships with pressure and reciprocal temperature. Typically, a change in temperature of 100°C results in a relative change in the elements of diffusion matrix of 50 to 100%, whereas a change in pressure of 1 GPa introduces a relative change in elements of diffusion matrix of 4 to 6% for the haplobasalt, and less than 5% for the haplodacite. At a pressure of 1 GPa, the ratios between the major and minor eigenvalues of the diffusion matrix λ1/λ2 are not very sensitive to temperature variations, with an average of 5.5 ± 0.2 for the haplobasalt and 3.7 ± 0.6 for the haplodacite. The activation energies for the major and minor eigenvalues of the diffusion matrix are 215 ± 12 and 240 ± 21 kJ mol-1, respectively, for the haplodacite and 192 ± 8 and 217 ± 14 kJ mol-1 for the haplobasalt. These values are comparable to the activation energies for self-diffusion of calcium and silicon at the same melt compositions and pressure. At a fixed temperature of 1500°C, the ratios λ1/λ2 increase with the increase of pressure, with λ1/λ2 varying from 2.5 to 4.1 (0.5 to 1.3 GPa) for the haplodacite and 4 to 6.5 (0.5 to 2.0 GPa) for the haplobasalt. The activation volumes for the major and minor eigenvalues of the diffusion matrix are 0.31 ± 0.44 and 2.3 ± 0.8 cm3 mol-1, respectively, for the haplodacite and -1.48 ± 0.18 and -0.42 ± 0.24 cm3 mol-1 for the haplobasalt. These values are quite different from the activation volumes for self-diffusion of calcium and silicon at the same melt compositions and temperature. These differences in activation volumes between the two melts likely result from a difference in the structure and thermodynamic properties of the melt between the two compositions (e.g., partial molar volume). Applications of the measured diffusion matrices to quartz crystal dissolution in molten CAS reveal that the activation energy and activation volume for quartz dissolution are almost identical to the activation energy and activation volume for diffusion of the minor or slower eigencomponent of the diffusion matrix. This suggests that the diffusion rate of slow eigencomponent is the rate-limiting factor in isothermal crystal dissolution, a conclusion that is likely to be valid for crystal growth and dissolution in natural magmas when diffusion in liquid is the rate-limiting factor.

Effect of cation structure on the oxygen solubility and diffusivity in a range of bis{(trifluoromethyl)sulfonyl}imide anion based ionic liquids for lithium-air battery electrolytes.

PubMed

Neale, Alex R; Li, Peilin; Jacquemin, Johan; Goodrich, Peter; Ball, Sarah C; Compton, Richard G; Hardacre, Christopher

2016-04-28

This paper reports on the solubility and diffusivity of dissolved oxygen in a series of ionic liquids (ILs) based on the bis{(trifluoromethyl)sulfonyl}imide anion with a range of related alkyl and ether functionalised cyclic alkylammonium cations. Cyclic voltammetry has been used to observe the reduction of oxygen in ILs at a microdisk electrode and chronoamperometric measurements have then been applied to simultaneously determine both the concentration and the diffusion coefficient of oxygen in different ILs. The viscosity of the ILs and the calculated molar volume and free volume are also reported. It is found that, within this class of ILs, the oxygen diffusivity generally increases with decreasing viscosity of the neat IL. An inverse relationship between oxygen solubility and IL free volume is reported for the two IL families implying that oxygen is not simply occupying the available empty space. In addition, it is reported that the introduction of an ether-group into the IL cation structure promotes the diffusivity of dissolved oxygen but reduces the solubility of the gas.

Comparison of flat cleaved and cylindrical diffusing fibers as treatment sources for interstitial photodynamic therapy.

PubMed

Baran, Timothy M; Foster, Thomas H

2014-02-01

For interstitial photodynamic therapy (iPDT) of bulky tumors, careful treatment planning is required in order to ensure that a therapeutic dose is delivered to the tumor, while minimizing damage to surrounding normal tissue. In clinical contexts, iPDT has typically been performed with either flat cleaved or cylindrical diffusing optical fibers as light sources. Here, the authors directly compare these two source geometries in terms of the number of fibers and duration of treatment required to deliver a prescribed light dose to a tumor volume. Treatment planning software for iPDT was developed based on graphics processing unit enhanced Monte Carlo simulations. This software was used to optimize the number of fibers, total energy delivered by each fiber, and the position of individual fibers in order to deliver a target light dose (D90) to 90% of the tumor volume. Treatment plans were developed using both flat cleaved and cylindrical diffusing fibers, based on tissue volumes derived from CT data from a head and neck cancer patient. Plans were created for four cases: fixed energy per fiber, fixed number of fibers, and in cases where both or neither of these factors were fixed. When the number of source fibers was fixed at eight, treatment plans based on flat cleaved fibers required each to deliver 7180-8080 J in order to deposit 90 J/cm(2) in 90% of the tumor volume. For diffusers, each fiber was required to deliver 2270-2350 J (333-1178 J/cm) in order to achieve this same result. For the case of fibers delivering a fixed 900 J, 13 diffusers or 19 flat cleaved fibers at a spacing of 1 cm were required to deliver the desired dose. With energy per fiber fixed at 2400 J and the number of fibers fixed at eight, diffuser fibers delivered the desired dose to 93% of the tumor volume, while flat cleaved fibers delivered this dose to 79%. With both energy and number of fibers allowed to vary, six diffusers delivering 3485-3600 J were required, compared to ten flat cleaved fibers delivering 2780-3600 J. For the same number of fibers, cylindrical diffusers allow for a shorter treatment duration compared to flat cleaved fibers. For the same energy delivered per fiber, diffusers allow for the insertion of fewer fibers in order to deliver the same light dose to a target volume.

Comparison of flat cleaved and cylindrical diffusing fibers as treatment sources for interstitial photodynamic therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baran, Timothy M., E-mail: timothy.baran@rochester.edu; Foster, Thomas H.

Purpose: For interstitial photodynamic therapy (iPDT) of bulky tumors, careful treatment planning is required in order to ensure that a therapeutic dose is delivered to the tumor, while minimizing damage to surrounding normal tissue. In clinical contexts, iPDT has typically been performed with either flat cleaved or cylindrical diffusing optical fibers as light sources. Here, the authors directly compare these two source geometries in terms of the number of fibers and duration of treatment required to deliver a prescribed light dose to a tumor volume. Methods: Treatment planning software for iPDT was developed based on graphics processing unit enhanced Montemore » Carlo simulations. This software was used to optimize the number of fibers, total energy delivered by each fiber, and the position of individual fibers in order to deliver a target light dose (D{sub 90}) to 90% of the tumor volume. Treatment plans were developed using both flat cleaved and cylindrical diffusing fibers, based on tissue volumes derived from CT data from a head and neck cancer patient. Plans were created for four cases: fixed energy per fiber, fixed number of fibers, and in cases where both or neither of these factors were fixed. Results: When the number of source fibers was fixed at eight, treatment plans based on flat cleaved fibers required each to deliver 7180–8080 J in order to deposit 90 J/cm{sup 2} in 90% of the tumor volume. For diffusers, each fiber was required to deliver 2270–2350 J (333–1178 J/cm) in order to achieve this same result. For the case of fibers delivering a fixed 900 J, 13 diffusers or 19 flat cleaved fibers at a spacing of 1 cm were required to deliver the desired dose. With energy per fiber fixed at 2400 J and the number of fibers fixed at eight, diffuser fibers delivered the desired dose to 93% of the tumor volume, while flat cleaved fibers delivered this dose to 79%. With both energy and number of fibers allowed to vary, six diffusers delivering 3485–3600 J were required, compared to ten flat cleaved fibers delivering 2780–3600 J. Conclusions: For the same number of fibers, cylindrical diffusers allow for a shorter treatment duration compared to flat cleaved fibers. For the same energy delivered per fiber, diffusers allow for the insertion of fewer fibers in order to deliver the same light dose to a target volume.« less

Magnetic resonance imaging evidence for presymptomatic change in thalamus and caudate in familial Alzheimer’s disease

PubMed Central

Keihaninejad, Shiva; Shakespeare, Timothy J.; Lehmann, Manja; Crutch, Sebastian J.; Malone, Ian B.; Thornton, John S.; Mancini, Laura; Hyare, Harpreet; Yousry, Tarek; Ridgway, Gerard R.; Zhang, Hui; Modat, Marc; Alexander, Daniel C.; Rossor, Martin N.; Ourselin, Sebastien; Fox, Nick C.

2013-01-01

Amyloid imaging studies of presymptomatic familial Alzheimer’s disease have revealed the striatum and thalamus to be the earliest sites of amyloid deposition. This study aimed to investigate whether there are associated volume and diffusivity changes in these subcortical structures during the presymptomatic and symptomatic stages of familial Alzheimer’s disease. As the thalamus and striatum are involved in neural networks subserving complex cognitive and behavioural functions, we also examined the diffusion characteristics in connecting white matter tracts. A cohort of 20 presenilin 1 mutation carriers underwent volumetric and diffusion tensor magnetic resonance imaging, neuropsychological and clinical assessments; 10 were symptomatic, 10 were presymptomatic and on average 5.6 years younger than their expected age at onset; 20 healthy control subjects were also studied. We conducted region of interest analyses of volume and diffusivity changes in the thalamus, caudate, putamen and hippocampus and examined diffusion behaviour in the white matter tracts of interest (fornix, cingulum and corpus callosum). Voxel-based morphometry and tract-based spatial statistics were also used to provide unbiased whole-brain analyses of group differences in volume and diffusion indices, respectively. We found that reduced volumes of the left thalamus and bilateral caudate were evident at a presymptomatic stage, together with increased fractional anisotropy of bilateral thalamus and left caudate. Although no significant hippocampal volume loss was evident presymptomatically, reduced mean diffusivity was observed in the right hippocampus and reduced mean and axial diffusivity in the right cingulum. In contrast, symptomatic mutation carriers showed increased mean, axial and in particular radial diffusivity, with reduced fractional anisotropy, in all of the white matter tracts of interest. The symptomatic group also showed atrophy and increased mean diffusivity in all of the subcortical grey matter regions of interest, with increased fractional anisotropy in bilateral putamen. We propose that axonal injury may be an early event in presymptomatic Alzheimer’s disease, causing an initial fall in axial and mean diffusivity, which then increases with loss of axonal density. The selective degeneration of long-coursing white matter tracts, with relative preservation of short interneurons, may account for the increase in fractional anisotropy that is seen in the thalamus and caudate presymptomatically. It may be owing to their dense connectivity that imaging changes are seen first in the thalamus and striatum, which then progress to involve other regions in a vulnerable neuronal network. PMID:23539189

Vacuum chamber-free centrifuge with magnetic bearings.

PubMed

Park, Cheol Hoon; Kim, Soohyun; Kim, Kyung-Soo

2013-09-01

Centrifuges are devices that separate particles of different densities and sizes through the application of a centrifugal force. If a centrifuge could be operated under atmospheric conditions, all vacuum-related components such as the vacuum chamber, vacuum pump, diffusion pump, and sealing could be removed from a conventional centrifuge system. The design and manufacturing procedure for centrifuges could then be greatly simplified to facilitate the production of lightweight centrifuge systems of smaller volume. Furthermore, the maintenance costs incurred owing to wear and tear due to conventional ball bearings would be eliminated. In this study, we describe a novel vacuum chamber-free centrifuge supported by magnetic bearings. We demonstrate the feasibility of the vacuum chamber-free centrifuge by presenting experimental results that verify its high-speed support capability and motoring power capacity.

The exit-time problem for a Markov jump process

NASA Astrophysics Data System (ADS)

Burch, N.; D'Elia, M.; Lehoucq, R. B.

2014-12-01

The purpose of this paper is to consider the exit-time problem for a finite-range Markov jump process, i.e, the distance the particle can jump is bounded independent of its location. Such jump diffusions are expedient models for anomalous transport exhibiting super-diffusion or nonstandard normal diffusion. We refer to the associated deterministic equation as a volume-constrained nonlocal diffusion equation. The volume constraint is the nonlocal analogue of a boundary condition necessary to demonstrate that the nonlocal diffusion equation is well-posed and is consistent with the jump process. A critical aspect of the analysis is a variational formulation and a recently developed nonlocal vector calculus. This calculus allows us to pose nonlocal backward and forward Kolmogorov equations, the former equation granting the various moments of the exit-time distribution.

Use of diffusion-weighted MRI to modify radiosurgery planning in brain metastases may reduce local recurrence.

PubMed

Zakaria, Rasheed; Pomschar, Andreas; Jenkinson, Michael D; Tonn, Jörg-Christian; Belka, Claus; Ertl-Wagner, Birgit; Niyazi, Maximilian

2017-02-01

Stereotactic radiosurgery (SRS) is an effective and well tolerated treatment for selected brain metastases; however, local recurrence still occurs. We investigated the use of diffusion weighted MRI (DWI) as an adjunct for SRS treatment planning in brain metastases. Seventeen consecutive patients undergoing complete surgical resection of a solitary brain metastasis underwent image analysis retrospectively. SRS treatment plans were generated based on standard 3D post-contrast T1-weighted sequences at 1.5T and then separately using apparent diffusion coefficient (ADC) maps in a blinded fashion. Control scans immediately post operation confirmed complete tumour resection. Treatment plans were compared to one another and with volume of local recurrence at progression quantitatively and qualitatively by calculating the conformity index (CI), the overlapping volume as a proportion of the total combined volume, where 1 = identical plans and 0 = no conformation whatsoever. Gross tumour volumes (GTVs) using ADC and post-contrast T1-weighted sequences were quantitatively the same (related samples Wilcoxon signed rank test = -0.45, p = 0.653) but showed differing conformations (CI 0.53, p < 0.001). The diffusion treatment volume (DTV) obtained by combining the two target volumes was significantly greater than the treatment volume based on post contrast T1-weighted MRI alone, both quantitatively (median 13.65 vs. 9.52 cm 3 , related samples Wilcoxon signed rank test p < 0.001) and qualitatively (CI 0.74, p = 0.001). This DTV covered a greater volume of subsequent tumour recurrence than the standard plan (median 3.53 cm 3 vs. 3.84 cm 3 , p = 0.002). ADC maps may be a useful tool in addition to the standard post-contrast T1-weighted sequence used for SRS planning.

Synthetic polymers blend used in the production of high activated carbon for pesticides removals from liquid phase.

PubMed

Belo, Cristóvão Ramiro; Cansado, Isabel Pestana da Paixão; Mourão, Paulo Alexandre Mira

2017-02-01

For the activated carbon (AC) production, we used the most common industrial and consumer solid waste, namely polyethyleneterephthalate (PET), alone or blended with other synthetic polymer such polyacrylonitrile (PAN). By mixing PET, with PAN, an improvement in the yield of the AC production was found and the basic character and some textural and chemical properties were enhanced. The PET-PAN mixture was subjected to carbonisation, with a pyrolysis yield of 31.9%, between that obtained with PET (16.9%) or PAN (42.6%) separately. The AC revealed a high surface area (1400, 1230 and 1117 m 2  g -1 ) and pore volume (0.46, 0.56 and 0.50 cm 3  g -1 ), respectively, for PET, PAN and PET-PAN precursors. Selected ACs were successfully tested for 4-chloro-2-methylphenoxyacetic acid (MCPA) and diuron removal from the liquid phase, showing a higher adsorption capacity (1.7 and 1.2 mmol g -1 , respectively, for MCPA and diuron) and good fits with the Langmuir (PET) and Freundlich equation (PAN and PET-PAN blend). With MCPA, the controlling factor to the adsorption capacity was the porous volume and the average pore size. Concerning diuron, the adsorption was controlled essentially by the external diffusion. A remarkable result is the use of different synthetic polymers wastes, as precursors for the production of carbon materials, with high potential application on the pesticides removals from the liquid phase.

Dynamic measurements of CO diffusing capacity using discrete samples of alveolar gas.

PubMed

Graham, B L; Mink, J T; Cotton, D J

1983-01-01

It has been shown that measurements of the diffusing capacity of the lung for CO made during a slow exhalation [DLCO(exhaled)] yield information about the distribution of the diffusing capacity in the lung that is not available from the commonly measured single-breath diffusing capacity [DLCO(SB)]. Current techniques of measuring DLCO(exhaled) require the use of a rapid-responding (less than 240 ms, 10-90%) CO meter to measure the CO concentration in the exhaled gas continuously during exhalation. DLCO(exhaled) is then calculated using two sample points in the CO signal. Because DLCO(exhaled) calculations are highly affected by small amounts of noise in the CO signal, filtering techniques have been used to reduce noise. However, these techniques reduce the response time of the system and may introduce other errors into the signal. We have developed an alternate technique in which DLCO(exhaled) can be calculated using the concentration of CO in large discrete samples of the exhaled gas, thus eliminating the requirement of a rapid response time in the CO analyzer. We show theoretically that this method is as accurate as other DLCO(exhaled) methods but is less affected by noise. These findings are verified in comparisons of the discrete-sample method of calculating DLCO(exhaled) to point-sample methods in normal subjects, patients with emphysema, and patients with asthma.

Proangiogenic and Profibrotic Markers in Pulmonary Sarcoidosis.

PubMed

Tuleta, I; Biener, L; Pizarro, C; Nickenig, G; Skowasch, D

2018-04-21

The aim of our study was to determine the blood levels of vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-β1, fibroblast growth factor (FGF)-2, and platelet-derived growth factor (PDGF)-AB in different stages of pulmonary sarcoidosis. There were 92 patients in sarcoidosis stages I + II, III, and IV enrolled into the study. All the patients underwent lung diffusing capacity and blood sampling. We found that VEGF levels differed significantly between the stage groups with the peak VEGF concentrations in stage III. TGF-β1 levels were similar in stages I + II and III, and tended to be lower in stage IV. The analysis of the subgroups showed increased VEGF and FGF-2, and reduced TGF-β1 concentration in stages I + II patients with relevantly reduced lung diffusing capacity or increased sarcoidosis activity compared to patients with normal lung diffusing capacity or inactive sarcoidosis. A tendency towards increased VEGF, PDGF-AB and TGF-β1 levels was observed in the analogical subgroup analysis within the stage III. We conclude that proangiogenic VEGF, and profibrotic FGF-2 and PDGF-AB may contribute to the progression of sarcoidosis, whereas TGF-β1, with its dual anti-inflammatory and profibrotic actions, may play a dichotomous protective or deleterious role. Reduced diffusing capacity and active sarcoidosis are associated with an unfavorable constellation of the markers studied, which predicts a progressive disease course.

Physical and thermal properties of mud-dominant sediment from the Joetsu Basin in the eastern margin of the Japan Sea

NASA Astrophysics Data System (ADS)

Goto, Shusaku; Yamano, Makoto; Morita, Sumito; Kanamatsu, Toshiya; Hachikubo, Akihiro; Kataoka, Satsuki; Tanahashi, Manabu; Matsumoto, Ryo

2017-12-01

Physical properties (bulk density and porosity) and thermal properties (thermal conductivity, heat capacity, specific heat, and thermal diffusivity) of sediment are crucial parameters for basin modeling. We measured these physical and thermal properties for mud-dominant sediment recovered from the Joetsu Basin, in the eastern margin of the Japan Sea. To determine thermal conductivity, heat capacity, and thermal diffusivity, the dual-needle probe method was applied. Grain density and grain thermal properties for the mud-dominant sediment were estimated from the measured physical and thermal properties by applying existing models of physical and thermal properties of sediment. We suggest that the grain density, grain thermal conductivity, and grain thermal diffusivity depend on the sediment mineral composition. Conversely, the grain heat capacity and grain specific heat showed hardly any dependency on the mineral composition. We propose empirical formulae for the relationships between: thermal diffusivity and thermal conductivity, and heat capacity and thermal conductivity for the sediment in the Joetsu Basin. These relationships are different from those for mud-dominant sediment in the eastern flank of the Juan de Fuca Ridge presented in previous work, suggesting a difference in mineral composition, probably mainly in the amount of quartz, between the sediments in that area and the Joetsu Basin. Similar studies in several areas of sediments with various mineral compositions would enhance knowledge of the influence of mineral composition.

Diffuse fluid flux through orogenic belts: Implications for the world ocean

USGS Publications Warehouse

Ingebritsen, S.E.; Manning, C.E.

2002-01-01

Fifty years ago a classic paper by W. W. Rubey [(1951) Geol. Soc. Am. Bull. 62, 1111-1148] examined various hypotheses regarding the origin of sea water and concluded that the most likely hypothesis was volcanic outgassing, a view that was generally accepted by earth scientists for the next several decades. More recent work suggests that the rate of subduction of water is much larger than the volcanic outgassing rate, lending support to hypotheses that either ocean volume has decreased with time, or that the imbalance is offset by continuous replenishment of water by cometary impacts. These alternatives are required in the absence of additional mechanisms for the return of water from subducting lithosphere to the Earth's surface. Our recent work on crustal permebility suggests a large capacity for water upflow through tectonically active continental crust, resulting in a heretofore unrecognized degassing pathway that can accommodate the waer subduction rate. Escape of recycled water via delivery from the mantle through zones of active metamorphism eliminates the mass-balance argument for the loss of ocean volume or extraterestrial sources.

Vital capacities in acute and chronic airway obstruction: dependence on flow and volume histories.

PubMed

Brusasco, V; Pellegrino, R; Rodarte, J R

1997-06-01

The aim of this study was to investigate whether measurements of vital capacity (VC) are affected by the direction of the manoeuvre (inspiratory vs expiratory) and by the rate of expiratory flow. The study was performed on 25 individuals with chronic airway obstruction (CAO) and a forced expiratory volume in one second (FEV1) (expressed in standardized residuals (SR)) of -2.0+/-1.4 SD (CAO group), and 10 asthmatic subjects with methacholine (MCh)-induced bronchoconstriction (FEV1 -23+/-1.02 SR) (MCh group). VCs were measured during fast inspiration following both slow (FIVCse) and forced (FIVCfe) expiration from end-tidal inspiration to residual volume (RV), and during slow (EVC) or forced (FVC) expiration from total lung capacity (TLC). In the CAO group, FVC was the smallest volume (3.75+/-1.03 L) and significantly different from the other three estimates of VC; FIVCse (4.03+/-0.91 L) was the largest volume and significantly different from FVC and FIVCfe (3.83+/-0.98 L). In the MCh group, FVC (4.16+/-0.94 L) and EVC (4.19+/-0.89 L) were the largest volumes, although only the difference between FVC and FIVCfe (3.76+/-0.81 L) reached statistical significance. These data suggest that both flow and volume histories contribute to decreased vital capacities during bronchoconstriction. However, whereas increasing expiratory flow always tends to decrease vital capacity, the volume history of full inflation has different effects in chronic and acute bronchoconstriction, probably due to different effects on airway calibre. These results stress the importance of using standardized manoeuvres in order to obtain comparable values of vital capacity.

Method for measurement of radon diffusion and solubility in solid materials

NASA Astrophysics Data System (ADS)

Maier, Andreas; Weber, Uli; Dickmann, Jannis; Breckow, Joachim; van Beek, Patrick; Schardt, Dieter; Kraft, Gerhard; Fournier, Claudia

2018-02-01

In order to study the permeation i.e. the diffusion and solubility of radon gas in biological material, a new setup was constructed and a novel analysis was applied to obtain diffusion and solubility coefficients. Thin slabs of solid materials were installed between detector housing and the surrounding radon exposure chamber of 50 Ls volume. In this setup radon can diffuse through thin test samples into a cylindrical volume of 5 mm height and 20 mm diameter and reach an α-particle detector. There the 5.49 MeV α-decay of the penetrating radon atoms is measured by a silicon surface barrier detector. The time dependent activities inside the small detector volume are recorded after injection of a known radon activity concentration into the outer chamber. Analyzing the time behavior of the integral α-activity from radon in the small vessel, both, the diffusion coefficient and solubility of the test material can be determined, based on a new mathematical model of the diffusion process concerning the special boundary conditions given by the experimental setup. These first measurements were intended as proof of concept for the detection system and the data analysis. Thin polyethylene foils (LDPE) were selected as material for the diffusion measurements and the results were in agreement with data from literature. In further measurements, we will concentrate on biological material like bone, fat and other tissues.

Apparent Diffusion Coefficient and Dynamic Contrast-Enhanced Magnetic Resonance Imaging in Pancreatic Cancer: Characteristics and Correlation With Histopathologic Parameters.

PubMed

Ma, Wanling; Li, Na; Zhao, Weiwei; Ren, Jing; Wei, Mengqi; Yang, Yong; Wang, Yingmei; Fu, Xin; Zhang, Zhuoli; Larson, Andrew C; Huan, Yi

2016-01-01

To clarify diffusion and perfusion abnormalities and evaluate correlation between apparent diffusion coefficient (ADC), MR perfusion and histopathologic parameters of pancreatic cancer (PC). Eighteen patients with PC underwent diffusion-weighted imaging and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Parameters of DCE-MRI and ADC of cancer and non-cancerous tissue were compared. Correlation between the rate constant that represents transfer of contrast agent from the arterial blood into the extravascular extracellular space (K, volume of the extravascular extracellular space per unit volume of tissue (Ve), and ADC of PC and histopathologic parameters were analyzed. The rate constant that represents transfer of contrast agent from the extravascular extracellular space into blood plasma, K, tissue volume fraction occupied by vascular space, and ADC of PC were significantly lower than nontumoral pancreases. Ve of PC was significantly higher than that of nontumoral pancreas. Apparent diffusion coefficient and K values of PC were negatively correlated to fibrosis content and fibroblast activation protein staining score. Fibrosis content was positively correlated to Ve. Apparent diffusion coefficient values and parameters of DCE-MRI can differentiate PC from nontumoral pancreases. There are correlations between ADC, K, Ve, and fibrosis content of PC. Fibroblast activation protein staining score of PC is negatively correlated to ADC and K. Apparent diffusion coefficient, K, and Ve may be feasible to predict prognosis of PC.

Prediction of pulmonary hypertension in idiopathic pulmonary fibrosis☆

PubMed Central

Zisman, David A.; Ross, David J.; Belperio, John A.; Saggar, Rajan; Lynch, Joseph P.; Ardehali, Abbas; Karlamangla, Arun S.

2007-01-01

Summary Background Reliable, noninvasive approaches to the diagnosis of pulmonary hypertension in idiopathic pulmonary fibrosis are needed. We tested the hypothesis that the forced vital capacity to diffusing capacity ratio and room air resting pulse oximetry may be combined to predict mean pulmonary artery pressure (MPAP) in idiopathic pulmonary fibrosis. Methods Sixty-one idiopathic pulmonary fibrosis patients with available right-heart catheterization were studied. We regressed measured MPAP as a continuous variable on pulse oximetry (SpO2) and percent predicted forced vital capacity (FVC) to percent-predicted diffusing capacity ratio (% FVC/% DLco) in a multivariable linear regression model. Results Linear regression generated the following equation: MPAP = −11.9+0.272 × SpO2+0.0659 × (100−SpO2)2+3.06 × (% FVC/% DLco); adjusted R2 = 0.55, p<0.0001. The sensitivity, specificity, positive predictive and negative predictive value of model-predicted pulmonary hypertension were 71% (95% confidence interval (CI): 50–89%), 81% (95% CI: 68–92%), 71% (95% CI: 51–87%) and 81% (95% CI: 68–94%). Conclusions A pulmonary hypertension predictor based on room air resting pulse oximetry and FVC to diffusing capacity ratio has a relatively high negative predictive value. However, this model will require external validation before it can be used in clinical practice. PMID:17604151

Comprehensive integrated spirometry using raised volume passive and forced expirations and multiple-breath nitrogen washout in infants

PubMed Central

Morris, Mohy G.

2009-01-01

With the rapid somatic growth and development in infants, simultaneous accurate measurements of lung volume and airway function are essential. Raised volume rapid thoracoabdominal compression (RTC) is widely used to generate forced expiration from an airway opening pressure of 30 cm H2O (V30). The (dynamic) functional residual capacity (FRCdyn) remains the lung volume most routinely measured. The aim of this study was to develop comprehensive integrated spirometry that included all subdivisions of lung volume at V30 or total lung capacity (TLC30). Measurements were performed on seventeen healthy infants aged 8.6–119.7 weeks. A commercial system for multiple-breath nitrogen washout (MBNW) to measure lung volumes and a custom made system to perform RTC were used in unison. A refined automated raised volume RTC and the following two novel single maneuvers with dual volume measurements were performed from V30 during a brief post-hyperventilation apneic pause: (1) the passive expiratory flow was integrated to produce the inspiratory capacity (IC) and the static (passive) FRC (FRCst) was estimated by initiating MBNW after end-passive expiration; (2) RTC was initiated late during passive expiration, flow was integrated to produce the slow vital capacity (jSVC) and the residual volume (RV) was measured by initiating MBNW after end-expiration while the jacket (j) was inflated. Intrasubject FRCdyn and FRCst measurements overlapped (p= 0.6420) but neither did with the RV (p<0.0001). Means (95% confidence interval) of FRCdyn, IC, FRCst, jSVC, RV, forced vital capacity and tidal volume were 21.2 (19.7–22.7), 36.7 (33.0–40.4), 21.2 (19.6–22.8), 40.7 (37.2–44.2), 18.1 (16.6–19.7), 40.7 (37.1–44.2) and 10.2 (9.6–10.7) ml/kg, respectively. Static lung volumes and capacities at V30 and variables from the best forced expiratory flow-volume curve were dependent on age, body length and weight. In conclusion, we developed a comprehensive physiologically-integrated approach for in-depth investigation of lung function at V30 in infants. PMID:19897058

Cell-centered high-order hyperbolic finite volume method for diffusion equation on unstructured grids

NASA Astrophysics Data System (ADS)

Lee, Euntaek; Ahn, Hyung Taek; Luo, Hong

2018-02-01

We apply a hyperbolic cell-centered finite volume method to solve a steady diffusion equation on unstructured meshes. This method, originally proposed by Nishikawa using a node-centered finite volume method, reformulates the elliptic nature of viscous fluxes into a set of augmented equations that makes the entire system hyperbolic. We introduce an efficient and accurate solution strategy for the cell-centered finite volume method. To obtain high-order accuracy for both solution and gradient variables, we use a successive order solution reconstruction: constant, linear, and quadratic (k-exact) reconstruction with an efficient reconstruction stencil, a so-called wrapping stencil. By the virtue of the cell-centered scheme, the source term evaluation was greatly simplified regardless of the solution order. For uniform schemes, we obtain the same order of accuracy, i.e., first, second, and third orders, for both the solution and its gradient variables. For hybrid schemes, recycling the gradient variable information for solution variable reconstruction makes one order of additional accuracy, i.e., second, third, and fourth orders, possible for the solution variable with less computational work than needed for uniform schemes. In general, the hyperbolic method can be an effective solution technique for diffusion problems, but instability is also observed for the discontinuous diffusion coefficient cases, which brings necessity for further investigation about the monotonicity preserving hyperbolic diffusion method.

Exercise-induced dehydration alters pulmonary function but does not modify airway responsiveness to dry air in athletes with mild asthma

PubMed Central

Romer, L. M.

2017-01-01

Local airway water loss is the main physiological trigger for exercise-induced bronchoconstriction (EIB). Our aim was to investigate the effects of whole body water loss on airway responsiveness and pulmonary function in athletes with mild asthma and/or EIB. Ten recreational athletes with a medical diagnosis of mild asthma and/or EIB completed a randomized, crossover study. Pulmonary function tests, including spirometry, whole body plethysmography, and diffusing capacity of the lung for carbon monoxide (DlCO), were conducted before and after three conditions: 1) 2 h of exercise in the heat with no fluid intake (dehydration), 2) 2 h of exercise with ad libitum fluid intake (control), and 3) a time-matched rest period (rest). Airway responsiveness was assessed 2 h postexercise/rest via eucapnic voluntary hyperpnea (EVH) to dry air. Exercise in the heat with no fluid intake induced a state of mild dehydration, with a body mass loss of 2.3 ± 0.8% (SD). After EVH, airway narrowing was not different between conditions: median (interquartile range) maximum fall in forced expiratory volume in 1 s was 13 (7–15)%, 11 (9–24)%, and 12 (7–20)% in dehydration, control, and rest conditions, respectively. Dehydration caused a significant reduction in forced vital capacity (300 ± 190 ml, P = 0.001) and concomitant increases in residual volume (260 ± 180 ml, P = 0.001) and functional residual capacity (260 ± 250 ml, P = 0.011), with no change in DlCO. Mild exercise-induced dehydration does not exaggerate airway responsiveness to dry air in athletes with mild asthma/EIB but may affect small airway function. NEW & NOTEWORTHY This study is the first to investigate the effect of whole body dehydration on airway responsiveness. Our data suggest that the airway response to dry air hyperpnea in athletes with mild asthma and/or exercise-induced bronchoconstriction is not exacerbated in a state of mild dehydration. On the basis of alterations in lung volumes, however, exercise-induced dehydration appears to compromise small airway function. PMID:28280109

Exercise-induced dehydration alters pulmonary function but does not modify airway responsiveness to dry air in athletes with mild asthma.

PubMed

Simpson, A J; Romer, L M; Kippelen, P

2017-05-01

Local airway water loss is the main physiological trigger for exercise-induced bronchoconstriction (EIB). Our aim was to investigate the effects of whole body water loss on airway responsiveness and pulmonary function in athletes with mild asthma and/or EIB. Ten recreational athletes with a medical diagnosis of mild asthma and/or EIB completed a randomized, crossover study. Pulmonary function tests, including spirometry, whole body plethysmography, and diffusing capacity of the lung for carbon monoxide (Dl CO ), were conducted before and after three conditions: 1 ) 2 h of exercise in the heat with no fluid intake (dehydration), 2 ) 2 h of exercise with ad libitum fluid intake (control), and 3 ) a time-matched rest period (rest). Airway responsiveness was assessed 2 h postexercise/rest via eucapnic voluntary hyperpnea (EVH) to dry air. Exercise in the heat with no fluid intake induced a state of mild dehydration, with a body mass loss of 2.3 ± 0.8% (SD). After EVH, airway narrowing was not different between conditions: median (interquartile range) maximum fall in forced expiratory volume in 1 s was 13 (7-15)%, 11 (9-24)%, and 12 (7-20)% in dehydration, control, and rest conditions, respectively. Dehydration caused a significant reduction in forced vital capacity (300 ± 190 ml, P = 0.001) and concomitant increases in residual volume (260 ± 180 ml, P = 0.001) and functional residual capacity (260 ± 250 ml, P = 0.011), with no change in Dl CO Mild exercise-induced dehydration does not exaggerate airway responsiveness to dry air in athletes with mild asthma/EIB but may affect small airway function. NEW & NOTEWORTHY This study is the first to investigate the effect of whole body dehydration on airway responsiveness. Our data suggest that the airway response to dry air hyperpnea in athletes with mild asthma and/or exercise-induced bronchoconstriction is not exacerbated in a state of mild dehydration. On the basis of alterations in lung volumes, however, exercise-induced dehydration appears to compromise small airway function. Copyright © 2017 the American Physiological Society.

Equivalence of Fluctuation Splitting and Finite Volume for One-Dimensional Gas Dynamics

NASA Technical Reports Server (NTRS)

Wood, William A.

1997-01-01

The equivalence of the discretized equations resulting from both fluctuation splitting and finite volume schemes is demonstrated in one dimension. Scalar equations are considered for advection, diffusion, and combined advection/diffusion. Analysis of systems is performed for the Euler and Navier-Stokes equations of gas dynamics. Non-uniform mesh-point distributions are included in the analyses.

Ti2Nb10O29-x mesoporous microspheres as promising anode materials for high-performance lithium-ion batteries

NASA Astrophysics Data System (ADS)

Deng, Shengjue; Luo, Zhibin; Liu, Yating; Lou, Xiaoming; Lin, Chunfu; Yang, Chao; Zhao, Hua; Zheng, Peng; Sun, Zhongliang; Li, Jianbao; Wang, Ning; Wu, Hui

2017-09-01

Ti2Nb10O29 has recently been reported as a promising anode material for lithium-ion batteries. However, its poor electronic conductivity and insufficient Li+-ion diffusion coefficient significantly limit its rate capability. To tackle this issue, a strategy combining nanosizing and crystal-structure modification is employed. Ti2Nb10O29-x mesoporous microspheres with a sphere-size range of 0.5-4 μm are prepared by a one-step solvothermal method followed by thermal treatment in N2. These Ti2Nb10O29-x mesoporous microspheres exhibit primary nanoparticles, a large specific surface area (22.9 m2 g-1) and suitable pore sizes, leading to easy electron/Li+-ion transport and good interfacial reactivity. Ti2Nb10O29-x shows a defective shear ReO3 crystal structure with O2- vacancies and an increased unit cell volume, resulting in its increased Li+-ion diffusion coefficient. Besides Ti4+ and Nb5+ ions, Ti2Nb10O29-x comprises Nb4+ ions with unpaired 4d electrons, which significantly increase its electronic conductivity. As a result of these improvements, the Ti2Nb10O29-x mesoporous microspheres reveal superior electrochemical performances in term of large reversible specific capacity (309 mAh g-1 at 0.1 C), outstanding rate capability (235 mAh g-1 at 40 C) and durable cyclic stability (capacity retention of 92.1% over 100 cycles at 10 C).

Enhanced adsorptive removal of methyl orange and methylene blue from aqueous solution by alkali-activated multiwalled carbon nanotubes.

PubMed

Ma, Jie; Yu, Fei; Zhou, Lu; Jin, Lu; Yang, Mingxuan; Luan, Jingshuai; Tang, Yuhang; Fan, Haibo; Yuan, Zhiwen; Chen, Junhong

2012-11-01

An alkali-acitvated method was explored to synthesize activated carbon nanotubes (CNTs-A) with a high specific surface area (SSA), and a large number of mesopores. The resulting CNTs-A were used as an adsorbent material for removal of anionic and cationic dyes in aqueous solutions. Experimental results indicated that CNTs-A have excellent adsorption capacity for methyl orange (149 mg/g) and methylene blue (399 mg/g). Alkali-activation treatment of CNTs increased the SSA and pore volume (PV), and introduced oxygen-containing functional groups on the surface of CNTs-A, which would be beneficial to improving the adsorption affinity of CNTs-A for removal of dyes. Kinetic regression results shown that the adsorption kinetic was more accurately represented by a pseudo second-order model. The overall adsorption process was jointly controlled by external mass transfer and intra-particle diffusion, and intra-particle diffusion played a dominant role. Freundlich isotherm model showed a better fit with adsorption data than Langmuir isotherm model. Adsorption interactions of dyes onto CNTs-A from aqueous solutions were investigated using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) method. The remarkable adsorption capacity of dye onto CNTs-A can be attributed to the multiple adsorption interaction mechanisms (hydrogen bonding, π-π electron-donor-acceptor interactions, electrostatic interactions, mesopore filling) on the CNTs-A. Results of this work are of great significance for environmental applications of activated CNTs as a promising adsorbent nanomaterial for organic pollutants from aqueous solutions.

User's manual for Axisymmetric Diffuser Duct (ADD) code. Volume 1: General ADD code description

NASA Technical Reports Server (NTRS)

Anderson, O. L.; Hankins, G. B., Jr.; Edwards, D. E.

1982-01-01

This User's Manual contains a complete description of the computer codes known as the AXISYMMETRIC DIFFUSER DUCT code or ADD code. It includes a list of references which describe the formulation of the ADD code and comparisons of calculation with experimental flows. The input/output and general use of the code is described in the first volume. The second volume contains a detailed description of the code including the global structure of the code, list of FORTRAN variables, and descriptions of the subroutines. The third volume contains a detailed description of the CODUCT code which generates coordinate systems for arbitrary axisymmetric ducts.

Interstitial and Interlayer Ion Diffusion Geometry Extraction in Graphitic Nanosphere Battery Materials.

PubMed

Gyulassy, Attila; Knoll, Aaron; Lau, Kah Chun; Wang, Bei; Bremer, Peer-Timo; Papka, Michael E; Curtiss, Larry A; Pascucci, Valerio

2016-01-01

Large-scale molecular dynamics (MD) simulations are commonly used for simulating the synthesis and ion diffusion of battery materials. A good battery anode material is determined by its capacity to store ion or other diffusers. However, modeling of ion diffusion dynamics and transport properties at large length and long time scales would be impossible with current MD codes. To analyze the fundamental properties of these materials, therefore, we turn to geometric and topological analysis of their structure. In this paper, we apply a novel technique inspired by discrete Morse theory to the Delaunay triangulation of the simulated geometry of a thermally annealed carbon nanosphere. We utilize our computed structures to drive further geometric analysis to extract the interstitial diffusion structure as a single mesh. Our results provide a new approach to analyze the geometry of the simulated carbon nanosphere, and new insights into the role of carbon defect size and distribution in determining the charge capacity and charge dynamics of these carbon based battery materials.

Interstitial and Interlayer Ion Diffusion Geometry Extraction in Graphitic Nanosphere Battery Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gyulassy, Attila; Knoll, Aaron; Lau, Kah Chun

2016-01-01

Large-scale molecular dynamics (MD) simulations are commonly used for simulating the synthesis and ion diffusion of battery materials. A good battery anode material is determined by its capacity to store ion or other diffusers. However, modeling of ion diffusion dynamics and transport properties at large length and long time scales would be impossible with current MD codes. To analyze the fundamental properties of these materials, therefore, we turn to geometric and topological analysis of their structure. In this paper, we apply a novel technique inspired by discrete Morse theory to the Delaunay triangulation of the simulated geometry of a thermallymore » annealed carbon nanosphere. We utilize our computed structures to drive further geometric analysis to extract the interstitial diffusion structure as a single mesh. Our results provide a new approach to analyze the geometry of the simulated carbon nanosphere, and new insights into the role of carbon defect size and distribution in determining the charge capacity and charge dynamics of these carbon based battery materials.« less

Interstitial and interlayer ion diffusion geometry extraction in graphitic nanosphere battery materials

DOE PAGES

Gyulassy, Attila; Knoll, Aaron; Lau, Kah Chun; ...

2016-01-31

Large-scale molecular dynamics (MD) simulations are commonly used for simulating the synthesis and ion diffusion of battery materials. A good battery anode material is determined by its capacity to store ion or other diffusers. However, modeling of ion diffusion dynamics and transport properties at large length and long time scales would be impossible with current MD codes. To analyze the fundamental properties of these materials, therefore, we turn to geometric and topological analysis of their structure. In this paper, we apply a novel technique inspired by discrete Morse theory to the Delaunay triangulation of the simulated geometry of a thermallymore » annealed carbon nanosphere. We utilize our computed structures to drive further geometric analysis to extract the interstitial diffusion structure as a single mesh. Lastly, our results provide a new approach to analyze the geometry of the simulated carbon nanosphere, and new insights into the role of carbon defect size and distribution in determining the charge capacity and charge dynamics of these carbon based battery materials.« less

Recovery of pulmonary functions, exercise capacity, and quality of life after pulmonary rehabilitation in survivors of ARDS due to severe influenza A (H1N1) pneumonitis.

PubMed

Hsieh, Meng-Jer; Lee, Wei-Chun; Cho, Hsiu-Ying; Wu, Meng-Fang; Hu, Han-Chung; Kao, Kuo-Chin; Chen, Ning-Hung; Tsai, Ying-Huang; Huang, Chung-Chi

2018-04-20

Acute respiratory distress syndrome (ARDS) due to severe influenza A H1N1 pneumonitis would result in impaired pulmonary functions and health-related quality of life (HRQoL) after hospital discharge. The recovery of pulmonary functions, exercise capacity, and HRQoL in the survivors of ARDS due to 2009 pandemic influenza A H1N1 pneumonitis (H1N1-ARDS) was evaluated in a tertiary teaching hospital in northern Taiwan between May 2010 and June 2011. Data of spirometry, total lung capacity (TLC), diffusing capacity of carbon monoxide (DL CO ), and 6-minute walk distance (6MWD) in the patients survived from H1N1-ARDS were collected 1, 3, and 6 months post-hospital discharge. HRQoL was evaluated with St. George respiratory questionnaire (SGRQ). Nine survivors of H1N1-ARDS in the study period were included. All these patients received 2 months' pulmonary rehabilitation program. Pulmonary functions and exercise capacity included TLC, forced vital capacity (FVC), forced expiratory volume in the first second (FEV 1 ), DL CO , and 6MWD improved from 1 to 3 months post-hospital discharge. Only TLC had further significant improvement from 3 to 6 months. HRQoL represented as the total score of SGRQ had no significant improvement in the first 3 months but improved significantly from 3 to 6 months post-discharge. The impaired pulmonary functions and exercise capacity in the survivors of H1N1-ARDS improved soon at 3 months after hospital discharge. Their quality of life had keeping improved at 6 months even though there was no further improvement of their pulmonary functions and exercise capacity. © 2018 The Authors. Influenza and Other Respiratory Viruses Published by John Wiley & Sons Ltd.

Investigation of oxygen self-diffusion in PuO 2 by combining molecular dynamics with thermodynamic calculations

DOE PAGES

Saltas, V.; Chroneos, A.; Cooper, Michael William D.; ...

2016-01-01

In the present work, the defect properties of oxygen self-diffusion in PuO 2 are investigated over a wide temperature (300–1900 K) and pressure (0–10 GPa) range, by combining molecular dynamics simulations and thermodynamic calculations. Based on the well-established cBΩ thermodynamic model which connects the activation Gibbs free energy of diffusion with the bulk elastic and expansion properties, various point defect parameters such as activation enthalpy, activation entropy, and activation volume were calculated as a function of T and P. Molecular dynamics calculations provided the necessary bulk properties for the proper implementation of the thermodynamic model, in the lack of anymore » relevant experimental data. The estimated compressibility and the thermal expansion coefficient of activation volume are found to be more than one order of magnitude greater than the corresponding values of the bulk plutonia. As a result, the diffusion mechanism is discussed in the context of the temperature and pressure dependence of the activation volume.« less

Activation volumes of oxygen self-diffusion in fluorite structured oxides

DOE PAGES

Christopoulos, S-R G.; Kordatos, A.; Cooper, Michael William D.; ...

2016-10-27

In this study, fluorite structured oxides are used in numerous applications and as such it is necessary to determine their materials properties over a range of conditions. In the present study we employ molecular dynamics calculations to calculate the elastic and expansivity data, which are then used in a thermodynamic model (the cBΩ model) to calculate the activation volumes of oxygen self-diffusion coefficient in ThO 2, UO 2 and PuO 2 fluorite structured oxides over a wide temperature range. We present relations to calculate the activation volumes of oxygen self-diffusion coefficient in ThO 2, UO 2 and PuO 2 formore » a wide range of temperature (300–1700 K) and pressure (–7.5 to 7.5 GPa).« less

The exit-time problem for a Markov jump process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burch, N.; D'Elia, Marta; Lehoucq, Richard B.

2014-12-15

The purpose of our paper is to consider the exit-time problem for a finite-range Markov jump process, i.e, the distance the particle can jump is bounded independent of its location. Such jump diffusions are expedient models for anomalous transport exhibiting super-diffusion or nonstandard normal diffusion. We refer to the associated deterministic equation as a volume-constrained nonlocal diffusion equation. The volume constraint is the nonlocal analogue of a boundary condition necessary to demonstrate that the nonlocal diffusion equation is well-posed and is consistent with the jump process. A critical aspect of the analysis is a variational formulation and a recently developedmore » nonlocal vector calculus. Furthermore, this calculus allows us to pose nonlocal backward and forward Kolmogorov equations, the former equation granting the various moments of the exit-time distribution.« less

Intraparticle diffusion limitations in the hydrogenation of monounsaturated edible oils and their fatty acid methyl esters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jonker, G.H.; Veldsink, J.W.; Beenackers, A.A.C.M.

1998-12-01

Intraparticle diffusion limitation in the hydrogenation and isomerization of fatty acid methyl esters (FAMEs) and edible oils (triacylglycerol, TAG) in porous nickel catalyst was investigated both under reactive and under inert conditions. Under reactive conditions, the diffusion coefficients were determined from the best fits of the model simulations applying the intrinsic reacting kinetics of monounsaturated FAME hydrogenation to experiments under diffusion limited conditions. Due to the absence of reaction (hydrogenation of double bonds), the obtained effective H{sub z} diffusion coefficient (D{sub e}) with the HPLC technique is volume averaged and thereby determined by the larger intercrystalline pores (<30% of themore » total pore volume) only. Moreover, D{sub e} measured under reaction conditions reflected the influence of the micropores, resulting in a 10-fold lower value.« less

Inspiratory capacity at inflation hold in ventilated newborns: a surrogate measure for static compliance of the respiratory system.

PubMed

Hentschel, Roland; Semar, Nicole; Guttmann, Josef

2012-09-01

To study appropriateness of respiratory system compliance calculation using an inflation hold and compare it with ventilator readouts of pressure and tidal volume as well as with measurement of compliance of the respiratory system with the single-breath-single-occlusion technique gained with a standard lung function measurement. Prospective clinical trial. Level III neonatal unit of a university hospital. Sixty-seven newborns, born prematurely or at term, ventilated for a variety of pathologic conditions. A standardized sigh maneuver with a predefined peak inspiratory pressure of 30 cm H2O, termed inspiratory capacity at inflation hold, was applied. Using tidal volume, exhaled from inspiratory pause down to ambient pressure, as displayed by the ventilator, and predefined peak inspiratory pressure, compliance at inspiratory capacity at inflation hold conditions could be calculated as well as ratio of tidal volume and ventilator pressure using tidal volume and differential pressure at baseline ventilator settings: peak inspiratory pressure minus positive end-expiratory pressure. For the whole cohort, the equation for the regression between tidal volume at inspiratory capacity at inflation hold and compliance of the respiratory system was: compliance of the respiratory system = 0.052 * tidal volume at inspiratory capacity at inflation hold - 0.113, and compliance at inspiratory capacity at inflation hold conditions was closely related to the standard lung function measurement method of compliance of the respiratory system (R = 0.958). In contrast, ratio of tidal volume and ventilator pressure per kilogram calculated from the ventilator readouts and displayed against compliance of the respiratory system per kilogram yielded a broad scatter throughout the whole range of compliance; both were only weakly correlated (R = 0.309) and also the regression line was significantly different from the line of identity (p < .05). Peak inspiratory pressure at study entry did not affect the correlation between compliance at inspiratory capacity at inflation hold conditions and compliance of the respiratory system. After a standard sigh maneuver, inspiratory capacity at inflation hold and the derived quantity compliance at inspiratory capacity at inflation hold conditions can be regarded as a valid, accurate, and reliable surrogate measure for standard compliance of the respiratory system in contrast to ratio of tidal volume and ventilator pressure calculated from the ventilator readouts during ongoing mechanical ventilation at respective ventilator settings.

Morphometric partitioning of the respiratory surface area and diffusion capacity of the gills and swim bladder in juvenile Amazonian air-breathing fish, Arapaima gigas.

PubMed

Fernandes, Marisa Narciso; da Cruz, André Luis; da Costa, Oscar Tadeu Ferreira; Perry, Steven Franklin

2012-09-01

The gills and the respiratory swim bladders of juvenile specimens (mean body mass 100g) of the basal teleost Arapaima gigas (Cuvier 1829) were evaluated using stereological methods in vertical sections. The surface areas, harmonic mean barrier thicknesses and morphometric diffusing capacities for oxygen and carbon dioxide were estimated. The average respiratory surface area of the swim bladder (2173 cm² kg⁻¹) exceeded that of the gills (780 cm² kg⁻¹) by a factor of 2.79. Due to the extremely thin air-blood barrier in the swim bladder (harmonic mean 0.22 μm) and the much thicker water-blood barrier of the gills (9.61 μm), the morphometric diffusing capacity for oxygen and carbon dioxide was 88 times greater in the swim bladder than in the gills. These data clearly indicate the importance of the swim bladder, even in juvenile A. gigas that still engage in aquatic respiration. Because of the much greater diffusion constant of CO₂ than O₂ in water, the gills also remain important for CO₂ release. Copyright © 2012 Elsevier Ltd. All rights reserved.

Can recording only the day-time voided volumes predict bladder capacity?

PubMed

Cho, Won Yeol; Kim, Seong Cheol; Kim, Sun-Ouck; Park, Sungchan; Lee, Sang Don; Chung, Jae Min; Kim, Kyung Do; Moon, Du Geon; Kim, Young Sig; Kim, Jun Mo

2018-05-01

This study aimed to demonstrate a method to easily assess bladder capacity using knowledge of day-time voided volumes, which can be obtained even from patients with nocturnal enuresis where the first morning void cannot accurately predict the bladder capacity due to bladder emptying overnight. We evaluated 177 healthy children from 7 Korean medical centres entered the study between January 2008 and January 2009. Voided volumes measured for more than 48 hours were recorded in the frequency volume chart (FVC). Most voided volumes during day-time were showed between 30% and 80% of the maximal voided volume (MVV). The maximal voided volume during day-time (MVVDT) was significantly less than the MVV (179.5±71.1 mL vs. 227.0±79.2 mL, p<0.001). The correlation coefficients with the MVV were 0.801 for the estimated MVV using the MVVDT (MVVDT×1.25), which suggested a fairly strong relationship between the MVVDT×1.25 and the MVV. The MVV derived from the FVC excluding the FMV was less than if the FMV had been included. When an accurate first morning voided volume cannot be obtained, as in patients with nocturnal enuresis, calculating MVVDT×1.25 allows estimation of the bladder capacity in place of the MVV.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chance, William W.; Rice, David C.; Allen, Pamela K.

Purpose: To investigate safety, efficacy, and recurrence after hemithoracic intensity modulated radiation therapy after pleurectomy/decortication (PD-IMRT) and after extrapleural pneumonectomy (EPP-IMRT). Methods and Materials: In 2009-2013, 24 patients with mesothelioma underwent PD-IMRT to the involved hemithorax to a dose of 45 Gy, with an optional integrated boost; 22 also received chemotherapy. Toxicity was scored with the Common Terminology Criteria for Adverse Events v4.0. Pulmonary function was compared at baseline, after surgery, and after IMRT. Kaplan-Meier analysis was used to calculate overall survival (OS), progression-free survival (PFS), time to locoregional failure, and time to distant metastasis. Failures were in-field, marginal, or outmore » of field. Outcomes were compared with those of 24 patients, matched for age, nodal status, performance status, and chemotherapy, who had received EPP-IMRT. Results: Median follow-up time was 12.2 months. Grade 3 toxicity rates were 8% skin and 8% pulmonary. Pulmonary function declined from baseline to after surgery (by 21% for forced vital capacity, 16% for forced expiratory volume in 1 second, and 19% for lung diffusion of carbon monoxide [P for all = .01]) and declined still further after IMRT (by 31% for forced vital capacity [P=.02], 25% for forced expiratory volume in 1 second [P=.01], and 30% for lung diffusion of carbon monoxide [P=.01]). The OS and PFS rates were 76% and 67%, respectively, at 1 year and 56% and 34% at 2 years. Median OS (28.4 vs 14.2 months, P=.04) and median PFS (16.4 vs 8.2 months, P=.01) favored PD-IMRT versus EPP-IMRT. No differences were found in grade 4-5 toxicity (0 of 24 vs 3 of 24, P=.23), median time to locoregional failure (18.7 months vs not reached, P not calculable), or median time to distant metastasis (18.8 vs 11.8 months, P=.12). Conclusions: Hemithoracic intensity modulated radiation therapy after pleurectomy/decortication produced little high-grade toxicity but led to progressive declines in pulmonary function; OS and PFS were better in PD-IMRT compared with EPP-IMRT.« less

Impact of Increasing Age on Cause-Specific Mortality and Morbidity in Patients With Stage I Non-Small-Cell Lung Cancer: A Competing Risks Analysis.

PubMed

Eguchi, Takashi; Bains, Sarina; Lee, Ming-Ching; Tan, Kay See; Hristov, Boris; Buitrago, Daniel H; Bains, Manjit S; Downey, Robert J; Huang, James; Isbell, James M; Park, Bernard J; Rusch, Valerie W; Jones, David R; Adusumilli, Prasad S

2017-01-20

Purpose To perform competing risks analysis and determine short- and long-term cancer- and noncancer-specific mortality and morbidity in patients who had undergone resection for stage I non-small-cell lung cancer (NSCLC). Patients and Methods Of 5,371 consecutive patients who had undergone curative-intent resection of primary lung cancer at our institution (2000 to 2011), 2,186 with pathologic stage I NSCLC were included in the analysis. All preoperative clinical variables known to affect outcomes were included in the analysis, specifically, Charlson comorbidity index, predicted postoperative (ppo) diffusing capacity of the lung for carbon monoxide, and ppo forced expiratory volume in 1 second. Cause-specific mortality analysis was performed with competing risks analysis. Results Of 2,186 patients, 1,532 (70.1%) were ≥ 65 years of age, including 638 (29.2%) ≥ 75 years of age. In patients < 65, 65 to 74, and ≥ 75 years of age, 5-year lung cancer-specific cumulative incidence of death (CID) was 7.5%, 10.7%, and 13.2%, respectively (overall, 10.4%); noncancer-specific CID was 1.8%, 4.9%, and 9.0%, respectively (overall, 5.3%). In patients ≥ 65 years of age, for up to 2.5 years after resection, noncancer-specific CID was higher than lung cancer-specific CID; the higher noncancer-specific, early-phase mortality was enhanced in patients ≥ 75 years of age than in those 65 to 74 years of age. Multivariable analysis showed that low ppo diffusing capacity of lung for carbon monoxide was an independent predictor of severe morbidity ( P < .001), 1-year mortality ( P < .001), and noncancer-specific mortality ( P < .001), whereas low ppo forced expiratory volume in 1 second was an independent predictor of lung cancer-specific mortality ( P = .002). Conclusion In patients who undergo curative-intent resection of stage I NSCLC, noncancer-specific mortality is a significant competing event, with an increasing impact as patient age increases.

Hemithoracic intensity modulated radiation therapy after pleurectomy/decortication for malignant pleural mesothelioma: toxicity, patterns of failure, and a matched survival analysis.

PubMed

Chance, William W; Rice, David C; Allen, Pamela K; Tsao, Anne S; Fontanilla, Hiral P; Liao, Zhongxing; Chang, Joe Y; Tang, Chad; Pan, Hubert Y; Welsh, James W; Mehran, Reza J; Gomez, Daniel R

2015-01-01

To investigate safety, efficacy, and recurrence after hemithoracic intensity modulated radiation therapy after pleurectomy/decortication (PD-IMRT) and after extrapleural pneumonectomy (EPP-IMRT). In 2009-2013, 24 patients with mesothelioma underwent PD-IMRT to the involved hemithorax to a dose of 45 Gy, with an optional integrated boost; 22 also received chemotherapy. Toxicity was scored with the Common Terminology Criteria for Adverse Events v4.0. Pulmonary function was compared at baseline, after surgery, and after IMRT. Kaplan-Meier analysis was used to calculate overall survival (OS), progression-free survival (PFS), time to locoregional failure, and time to distant metastasis. Failures were in-field, marginal, or out of field. Outcomes were compared with those of 24 patients, matched for age, nodal status, performance status, and chemotherapy, who had received EPP-IMRT. Median follow-up time was 12.2 months. Grade 3 toxicity rates were 8% skin and 8% pulmonary. Pulmonary function declined from baseline to after surgery (by 21% for forced vital capacity, 16% for forced expiratory volume in 1 second, and 19% for lung diffusion of carbon monoxide [P for all = .01]) and declined still further after IMRT (by 31% for forced vital capacity [P=.02], 25% for forced expiratory volume in 1 second [P=.01], and 30% for lung diffusion of carbon monoxide [P=.01]). The OS and PFS rates were 76% and 67%, respectively, at 1 year and 56% and 34% at 2 years. Median OS (28.4 vs 14.2 months, P=.04) and median PFS (16.4 vs 8.2 months, P=.01) favored PD-IMRT versus EPP-IMRT. No differences were found in grade 4-5 toxicity (0 of 24 vs 3 of 24, P=.23), median time to locoregional failure (18.7 months vs not reached, P not calculable), or median time to distant metastasis (18.8 vs 11.8 months, P=.12). Hemithoracic intensity modulated radiation therapy after pleurectomy/decortication produced little high-grade toxicity but led to progressive declines in pulmonary function; OS and PFS were better in PD-IMRT compared with EPP-IMRT. Copyright © 2015 Elsevier Inc. All rights reserved.

Heat Fluxes and Evaporation Measurements by Multi-Function Heat Pulse Probe: a Laboratory Experiment

NASA Astrophysics Data System (ADS)

Sharma, V.; Ciocca, F.; Hopmans, J. W.; Kamai, T.; Lunati, I.; Parlange, M. B.

2012-04-01

Multi Functional Heat Pulse Probes (MFHPP) are multi-needles probes developed in the last years able to measure temperature, thermal properties such as thermal diffusivity and volumetric heat capacity, from which soil moisture is directly retrieved, and electric conductivity (through a Wenner array). They allow the simultaneous measurement of coupled heat, water and solute transport in porous media, then. The use of only one instrument to estimate different quantities in the same volume and almost at the same time significantly reduces the need to interpolate different measurement types in space and time, increasing the ability to study the interdependencies characterizing the coupled transports, especially of water and heat, and water and solute. A three steps laboratory experiment is realized at EPFL to investigate the effectiveness and reliability of the MFHPP responses in a loamy soil from Conthey, Switzerland. In the first step specific calibration curves of volumetric heat capacity and thermal conductivity as function of known volumetric water content are obtained placing the MFHPP in small samplers filled with the soil homogeneously packed at different saturation degrees. The results are compared with literature values. In the second stage the ability of the MFHPP to measure heat fluxes is tested within a homemade thermally insulated calibration box and results are matched with those by two self-calibrating Heatflux plates (from Huxseflux), placed in the same box. In the last step the MFHPP are used to estimate the cumulative subsurface evaporation inside a small column (30 centimeters height per 8 centimeters inner diameter), placed on a scale, filled with the same loamy soil (homogeneously packed and then saturated) and equipped with a vertical array of four MFHPP inserted close to the surface. The subsurface evaporation is calculated from the difference between the net sensible heat and the net heat storage in the volume scanned by the probes, and the values obtained are matched with the overall evaporation, estimated through the scale in terms of weight loss. A numerical model able to solve the coupled heat-moisture diffusive equations is used to interpolate the obtained measures in the second and third step.

Manual dexterity and brain structure in patients with schizophrenia: A whole-brain magnetic resonance imaging study.

PubMed

Hidese, Shinsuke; Ota, Miho; Sasayama, Daimei; Matsuo, Junko; Ishida, Ikki; Hiraishi, Moeko; Teraishi, Toshiya; Hattori, Kotaro; Kunugi, Hiroshi

2018-04-14

The Purdue Pegboard Test (PPT) is a motor coordination task used to assess manual dexterity. Although several brain regions are thought to be involved in PPT performance, the relationship of the task with decreased insular volume has not been investigated. The PPT was administered to 83 subjects diagnosed with schizophrenia (mean ± standard deviation age: 38.6 ± 11.2 years; 47 males, 36 females) and 130 healthy controls (42.1 ± 15.2 years; 67 males, 63 females). All subjects were Japanese and right-handed. Gray matter volume was analyzed using voxel-based morphometry in statistical parametric mapping, while white matter measures were analyzed using diffusion tensor imaging in tract-based spatial statistics. For the patients with schizophrenia, the left-hand scores positively correlated with the right insular and bilateral operculum volumes, while the summation score (sum of left-, right-, and both-hands scores) positively correlated with the right insular volume, and the summation and assembly (number of assemblies completed) scores correlated with the diffuse white matter fractional anisotropy, axial diffusivity, and radial diffusivity values. In contrast, no significant correlations were found for the controls. These results suggested that decreased insular volume and white matter measures contributed to the impairments in manual dexterity observed in subjects with schizophrenia. Copyright © 2018 Elsevier B.V. All rights reserved.

Diffusion Profiles of Health Beneficial Components from Goji Berry (Lyceum barbarum) Marinated in Alcohol and Their Antioxidant Capacities as Affected by Alcohol Concentration and Steeping Time

PubMed Central

Song, Yang; Xu, Baojun

2013-01-01

The fruit (goji berry) of Lycium barbarum, a traditional Chinese medicine, has been widely used in health diets due to its potential role in the prevention of chronic diseases. One of the most popular applications of goji berry is to make goji wine in China by steeping goji berry in grain liquor. However, how the steeping process affects antioxidant capacities and phytochemicals of goji berry is not yet fully understood. Therefore, to provide scientific data for the utilization of goji berry in the nutraceutical industry, the diffusion rate of betaine, β-carotene, phenolic compounds in goji berry and their antioxidant capacities affected by alcohol concentration and steeping time were determined by UV-Visible spectrophotometer. The results showed that low alcohol concentration (15% or 25%) would promote the diffusion of betaine and increase antioxidant activity, while high concentration (55% or 65%) would generally increase the diffusion of flavonoids and reduce antioxidant activity. The steeping time had no significant effect on the diffusion of phenolic compounds and antioxidant activities. However, all goji berry wine steeped for 14 days with different alcohol concentrations exhibited the highest betaine concentration. Current findings provide useful information for the nutraceutical industries to choose proper steeping time and alcohol concentration to yield desired health promotion components from goji. PMID:28239094

An order insertion scheduling model of logistics service supply chain considering capacity and time factors.

PubMed

Liu, Weihua; Yang, Yi; Wang, Shuqing; Liu, Yang

2014-01-01

Order insertion often occurs in the scheduling process of logistics service supply chain (LSSC), which disturbs normal time scheduling especially in the environment of mass customization logistics service. This study analyses order similarity coefficient and order insertion operation process and then establishes an order insertion scheduling model of LSSC with service capacity and time factors considered. This model aims to minimize the average unit volume operation cost of logistics service integrator and maximize the average satisfaction degree of functional logistics service providers. In order to verify the viability and effectiveness of our model, a specific example is numerically analyzed. Some interesting conclusions are obtained. First, along with the increase of completion time delay coefficient permitted by customers, the possible inserting order volume first increases and then trends to be stable. Second, supply chain performance reaches the best when the volume of inserting order is equal to the surplus volume of the normal operation capacity in mass service process. Third, the larger the normal operation capacity in mass service process is, the bigger the possible inserting order's volume will be. Moreover, compared to increasing the completion time delay coefficient, improving the normal operation capacity of mass service process is more useful.

[Function in patients with chronic fibrocavernous tuberculosis].

PubMed

Nefedov, V B; Popova, L A; Shergina, E A

2008-01-01

Vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/VC%, PEF, MEF25, MEF50, MEF75, TLC, TGV, residual volume (RV), R(aw), R(in), R(ex), DLCO-SB, DLCO-SS, PaO2, and PaCO2 were determined in 62 patients with chronic fibrocavernous tuberculosis. Lung dysfunctions were detected in 96.8% of the patients. Changes in lung volumes and capacities were found in 90.3%, impaired bronchial patency was in 90.3%, and pulmonary gas exchange dysfunction was in 79.0%. The lung volume and capacity changes appeared as decreased VC and FVC, decreased and increased TLC, TGV, RV; impaired bronchial patency presented as decreased PEF, MEF25, MEF50, MEF75, and FEV1/VC%; and increased R(aw), R(in), R(ex); pulmonary gas exchange dysfunction manifested itself as reduced DLCO-SB, DLCO-SS, PaO2, and decreased and increased PaCO2. The magnitude of the observed functional changes ranges from slight to significant and drastic with a predominance of considerable and drastic changes in lung volumes and capacities and mild impairments of bronchial patency and pulmonary gas exchange function.

Effects of diffusion on total biomass in heterogeneous continuous and discrete-patch systems

USGS Publications Warehouse

DeAngelis, Donald L.; Ming Ni, Wei; Zhang, Bo

2016-01-01

Theoretical models of populations on a system of two connected patches previously have shown that when the two patches differ in maximum growth rate and carrying capacity, and in the limit of high diffusion, conditions exist for which the total population size at equilibrium exceeds that of the ideal free distribution, which predicts that the total population would equal the total carrying capacity of the two patches. However, this result has only been shown for the Pearl-Verhulst growth function on two patches and for a single-parameter growth function in continuous space. Here, we provide a general criterion for total population size to exceed total carrying capacity for three commonly used population growth rates for both heterogeneous continuous and multi-patch heterogeneous landscapes with high population diffusion. We show that a sufficient condition for this situation is that there is a convex positive relationship between the maximum growth rate and the parameter that, by itself or together with the maximum growth rate, determines the carrying capacity, as both vary across a spatial region. This relationship occurs in some biological populations, though not in others, so the result has ecological implications.

Analytical and computational studies on the vacuum performance of a chevron ejector

NASA Astrophysics Data System (ADS)

Kong, F. S.; Jin, Y. Z.; Kim, H. D.

2016-11-01

The effects of chevrons on the performance of a supersonic vacuum ejector-diffuser system are investigated numerically and evaluated theoretically in this work. A three-dimensional geometrical domain is numerically solved using a fully implicit finite volume scheme based on the unsteady Reynolds stress model. A one-dimensional mathematical model provides a useful tool to reveal the steady flow physics inside the vacuum ejector-diffuser system. The effects of the chevron nozzle on the generation of recirculation regions and Reynolds stress behaviors are studied and compared with those of a conventional convergent nozzle. The present performance parameters obtained from the simulated results and the mathematical results are validated with existing experimental data and show good agreement. Primary results show that the duration of the transient period and the secondary chamber pressure at a dynamic equilibrium state depend strongly on the primary jet conditions, such as inlet pressure and primary nozzle shape. Complicated oscillatory flow, generated by the unsteady movement of recirculation, finally settles into a dynamic equilibrium state. As a vortex generator, the chevron demonstrated its strong entrainment capacity to accelerate the starting transient flows to a certain extent and reduce the dynamic equilibrium pressure of the secondary chamber significantly.

Adsorption of methylene blue onto activated carbon produced from tea (Camellia sinensis L.) seed shells: kinetics, equilibrium, and thermodynamics studies.

PubMed

Gao, Jun-Jie; Qin, Ye-Bo; Zhou, Tao; Cao, Dong-Dong; Xu, Ping; Hochstetter, Danielle; Wang, Yue-Fei

2013-07-01

Tea (Camellia sinensis L.) seed shells, the main byproduct of the manufacture of tea seed oil, were used as precursors for the preparation of tea activated carbon (TAC) in the present study. A high yield (44.1%) of TAC was obtained from tea seed shells via a one-step chemical method using ZnCl2 as an agent. The Brunauer-Emmett-Teller (BET) surface area and the total pore volumes of the obtained TAC were found to be 1530.67 mg(2)/g and 0.7826 cm(3)/g, respectively. The equilibrium adsorption results were complied with Langmuir isotherm model and its maximum monolayer adsorption capacity was 324.7 mg/g for methylene blue. Adsorption kinetics studies indicated that the pseudo-second-order model yielded the best fit for the kinetic data. An intraparticle diffusion model suggested that the intraparticle diffusion was not the only rate-controlling step. Thermodynamics studies revealed the spontaneous and exothermic nature of the sorption process. These results indicate that tea seed shells could be utilized as a renewable resource to develop activated carbon which is a potential adsorbent for methylene blue.

Adsorption of methylene blue onto activated carbon produced from tea (Camellia sinensis L.) seed shells: kinetics, equilibrium, and thermodynamics studies*

PubMed Central

Gao, Jun-jie; Qin, Ye-bo; Zhou, Tao; Cao, Dong-dong; Xu, Ping; Hochstetter, Danielle; Wang, Yue-fei

2013-01-01

Tea (Camellia sinensis L.) seed shells, the main byproduct of the manufacture of tea seed oil, were used as precursors for the preparation of tea activated carbon (TAC) in the present study. A high yield (44.1%) of TAC was obtained from tea seed shells via a one-step chemical method using ZnCl2 as an agent. The Brunauer-Emmett-Teller (BET) surface area and the total pore volumes of the obtained TAC were found to be 1 530.67 mg2/g and 0.782 6 cm3/g, respectively. The equilibrium adsorption results were complied with Langmuir isotherm model and its maximum monolayer adsorption capacity was 324.7 mg/g for methylene blue. Adsorption kinetics studies indicated that the pseudo-second-order model yielded the best fit for the kinetic data. An intraparticle diffusion model suggested that the intraparticle diffusion was not the only rate-controlling step. Thermodynamics studies revealed the spontaneous and exothermic nature of the sorption process. These results indicate that tea seed shells could be utilized as a renewable resource to develop activated carbon which is a potential adsorbent for methylene blue. PMID:23825151

The active surface of suspended particles as a predictor of lung function and pulmonary symptoms in Austrian school children

NASA Astrophysics Data System (ADS)

Moshammer, Hanns; Neuberger, Manfred

At a central elementary school in the capital of Upper Austria children aged 7-10 years underwent repeated respiratory health checkups (questionnaires, diaries, spirometry). Between March and May 2001 the daily means of the signals of a diffusion charging sensor, measuring the "active surface" of suspended particles, and a photoelectric aerosol sensor, measuring the particle-bound polycyclic aromatic hydrocarbons, were related to spirometric results of the total 164 children examined and to the daily symptom scores of a susceptible subgroup. Significant reductions of forced vital capacity ( p=0.006) and forced expiratory volume in the first second ( p=0.001) and significant increases of wheezing ( p=0.001), shortness of breath ( p=0.041), cough in the evening ( p=0.031) and at night ( p=0.018) were found with increase of "active surface" of suspended particles measured at the adjacent outdoor monitoring station, but not with the increase of particle-bound polycyclic aromatic hydrocarbons. Monitoring "active surface" of particles with diameters of about 10 nm-1 μm by means of a diffusion charging sensor might provide additional information in surveillance of particulate matter for prevention of acute effects on respiratory health.

Combined Hydrous Ferric Oxide and Quaternary Ammonium Surfactant Tailoring of Granular Activated Carbon for Concurrent Arsenate and Perchlorate Removal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jang, M.; Cannon, F; Parette, R

2009-01-01

Activated carbon was tailored with both iron and quaternary ammonium surfactants so as to concurrently remove both arsenate and perchlorate from groundwater. The iron (hydr)oxide preferentially removed the arsenate oxyanion but not perchlorate; while the quaternary ammonium preferentially removed the perchlorate oxyanion, but not the arsenate. The co-sorption of two anionic oxyanions via distinct mechanisms has yielded intriguing phenomena. Rapid small-scale column tests (RSSCTs) with these dually prepared media employed synthetic waters that were concurrently spiked with arsenate and perchlorate; and these trial results showed that the quaternary ammonium surfactants enhanced arsenate removal bed life by 25-50% when compared tomore » activated carbon media that had been preloaded merely with iron (hydr)oxide; and the surfactant also enhanced the diffusion rate of arsenate per the Donnan effect. The authors also employed natural groundwater from Rutland, MA which contained 60 microg/L As and traces of silica, and sulfate; and the authors spiked this with 40 microg/L perchlorate. When processing this water, activated carbon that had been tailored with iron and cationic surfactant could treat 12,500 bed volumes before 10 microg/L arsenic breakthrough, and 4500 bed volumes before 6 microg/L perchlorate breakthrough. Although the quaternary ammonium surfactants exhibited only a slight capacity for removing arsenate, these surfactants did facilitate a more favorably positively charged avenue for the arsenate to diffuse through the media to the iron sorption site (i.e. via the Donnan effect).« less

Adsorption of lignite-derived humic acids on coal-based mesoporous activated carbons.

PubMed

Lorenc-Grabowska, Ewa; Gryglewicz, Grazyna

2005-04-15

The adsorption by a coal-based mesoporous activated carbon of humic acids (HAs) isolated from two Polish lignites was studied. For comparison, a commercial Aldrich humic acid was also included into this study. The differences in chemical structure and functional groups of HAs were determined by elemental analysis and infrared spectroscopy DRIFT. Two activated carbons used differed in terms of mesopore volume, mesopore size distribution, and chemical properties of the surface. The kinetics of adsorption of HAs have been discussed using three kinetic models, i.e., the first-order Lagergren model, the pseudo-second-order model, and the intraparticle diffusion model. It was found that the adsorption of HAs from alkaline solution on mesoporous activated carbon proceeds according to the pseudo-second-order model. The correlation coefficients were close to 1. The intraparticle diffusion of HA molecules within the carbon particle was identified to be the rate-limiting step. Comparing the two activated carbons, the carbon with a higher volume of pores with widths of 10-50 nm showed a greater removal efficiency of HA. An increase in the Freundlich adsorption capacity with decreasing carbon content of HA was observed. Among the HAs studied, S-HA shows characteristics indicating the highest contribution of small-size fraction. The S-HA was removed by both activated carbons to the highest extent. The effect of pH solution on the adsorption of HA was examined over the range pH 5.4-12.2. It was found that the extent of adsorption decreased with decreasing pH of the solution.

Diffusion of pent-1-ene (1); air (2)

NASA Astrophysics Data System (ADS)

Winkelmann, J.

This document is part of Subvolume A `Gases in Gases, Liquids and their Mixtures' of Volume 15 `Diffusion in Gases, Liquids and Electrolytes' of Landolt-Börnstein Group IV `Physical Chemistry'. It is part of the chapter of the chapter `Diffusion in Pure Gases' and contains data on diffusion of (1) pent-1-ene; (2) air

Generalized Fourier analyses of the advection-diffusion equation - Part I: one-dimensional domains

NASA Astrophysics Data System (ADS)

Christon, Mark A.; Martinez, Mario J.; Voth, Thomas E.

2004-07-01

This paper presents a detailed multi-methods comparison of the spatial errors associated with finite difference, finite element and finite volume semi-discretizations of the scalar advection-diffusion equation. The errors are reported in terms of non-dimensional phase and group speed, discrete diffusivity, artificial diffusivity, and grid-induced anisotropy. It is demonstrated that Fourier analysis provides an automatic process for separating the discrete advective operator into its symmetric and skew-symmetric components and characterizing the spectral behaviour of each operator. For each of the numerical methods considered, asymptotic truncation error and resolution estimates are presented for the limiting cases of pure advection and pure diffusion. It is demonstrated that streamline upwind Petrov-Galerkin and its control-volume finite element analogue, the streamline upwind control-volume method, produce both an artificial diffusivity and a concomitant phase speed adjustment in addition to the usual semi-discrete artifacts observed in the phase speed, group speed and diffusivity. The Galerkin finite element method and its streamline upwind derivatives are shown to exhibit super-convergent behaviour in terms of phase and group speed when a consistent mass matrix is used in the formulation. In contrast, the CVFEM method and its streamline upwind derivatives yield strictly second-order behaviour. In Part II of this paper, we consider two-dimensional semi-discretizations of the advection-diffusion equation and also assess the affects of grid-induced anisotropy observed in the non-dimensional phase speed, and the discrete and artificial diffusivities. Although this work can only be considered a first step in a comprehensive multi-methods analysis and comparison, it serves to identify some of the relative strengths and weaknesses of multiple numerical methods in a common analysis framework. Published in 2004 by John Wiley & Sons, Ltd.

Effect of prolonged bed rest on lung volume in normal individuals

NASA Technical Reports Server (NTRS)

Beckett, W. S.; Vroman, N. B.; Nigro, D.; Thompson-Gorman, S.; Wilkerson, J. E.

1986-01-01

The effect of prolonged bed rest on the lung function was studied by measuring forced vital capacity (FVC) and total lung capacity (TLC) in normal subjects before, during, and after 11- to 12-day rest periods. It was found that both FVC and TLC increased during bed rest (compared with the ambulatory controls), while residual volume and functional residual capacity of the respiratory system did not change. It is concluded that the increase in TLC by prolonged bed rest is not dependent on alterations in plasma volume.

Structural modulation of brain development by oxygen: evidence on adolescents migrating from high altitude to sea level environment.

PubMed

Zhang, Jiaxing; Zhang, Haiyan; Chen, Ji; Fan, Ming; Gong, Qiyong

2013-01-01

The present study aimed to investigate structural modulation of brain by high level of oxygen during its peak period of development. Voxel-based morphometry analysis of gray matter (GM) and white matter (WM) volumes and Tract-Based Spatial Statistics analysis of WM fractional anisotropy (FA) and mean diffusion (MD) based on MRI images were carried out on 21 Tibetan adolencents (15-18 years), who were born and raised in Qinghai-Tibetan Plateau (2900-4700 m) and have lived at sea level (SL) in the last 4 years. The control group consisted of matched Tibetan adolescents born and raised at high altitude all the time. SL immigrants had increased GM volume in the left insula, left inferior parietal gyrus, and right superior parietal gyrus and decreased GM in the left precentral cortex and multiple sites in cerebellar cortex (left lobule 8, bilateral lobule 6 and crus 1/2). Decreased WM volume was found in the right superior frontal gyrus in SL immigrants. SL immigrants had higher FA and lower MD at multiple sites of WM tracts. Moreover, we detected changes in ventilation and circulation. GM volume in cerebellum lobule 8 positively correlated with diastolic pressure, while GM volume in insula positively correlated vital capacity and hypoxic ventilatory response. Our finding indicate that the structural modulations of GM by high level of oxygen during its peak period of development are related to respiratory and circulatory regulations, while the modulation in WM mainly exhibits an enhancement in myelin maturation.

Lobar analysis of collapsibility indices to assess functional lung volumes in COPD patients.

PubMed

Kitano, Mariko; Iwano, Shingo; Hashimoto, Naozumi; Matsuo, Keiji; Hasegawa, Yoshinori; Naganawa, Shinji

2014-01-01

We investigated correlations between lung volume collapsibility indices and pulmonary function test (PFT) results and assessed lobar differences in chronic obstructive pulmonary disease (COPD) patients, using paired inspiratory and expiratory three dimensional (3D) computed tomography (CT) images. We retrospectively assessed 28 COPD patients who underwent paired inspiratory and expiratory CT and PFT exams on the same day. A computer-aided diagnostic system calculated total lobar volume and emphysematous lobar volume (ELV). Normal lobar volume (NLV) was determined by subtracting ELV from total lobar volume, both for inspiratory phase (NLVI) and for expiratory phase (NLVE). We also determined lobar collapsibility indices: NLV collapsibility ratio (NLVCR) (%)=(1-NLVE/NLVI)×100%. Associations between lobar volumes and PFT results, and collapsibility indices and PFT results were determined by Pearson correlation analysis. NLVCR values were significantly correlated with PFT results. Forced expiratory volume in 1 second, measured as percent of predicted results (FEV1%P) was significantly correlated with NLVCR values for the lower lobes (P<0.01), whereas this correlation was not significant for the upper lobes (P=0.05). FEV1%P results were also moderately correlated with inspiratory, expiratory ELV (ELVI,E) for the lower lobes (P<0.05). In contrast, the ratio of the diffusion capacity for carbon monoxide to alveolar gas volume, measured as percent of predicted (DLCO/VA%P) results were strongly correlated with ELVI for the upper lobes (P<0.001), whereas this correlation with NLVCR values was weaker for upper lobes (P<0.01) and was not significant for the lower lobes (P=0.26). FEV1%P results were correlated with NLV collapsibility indices for lower lobes, whereas DLCO/VA%P results were correlated with NLV collapsibility indices and ELV for upper lobes. Thus, evaluating lobar NLV collapsibility might be useful for estimating pulmonary function in COPD patients.

Role of MRI in osteosarcoma for evaluation and prediction of chemotherapy response: correlation with histological necrosis.

PubMed

Bajpai, Jyoti; Gamnagatti, Shivanand; Kumar, Rakesh; Sreenivas, Vishnubhatla; Sharma, Mehar Chand; Khan, Shah Alam; Rastogi, Shishir; Malhotra, Arun; Safaya, Rajni; Bakhshi, Sameer

2011-04-01

Histological necrosis, the current standard for response evaluation in osteosarcoma, is attainable after neoadjuvant chemotherapy. To establish the role of surrogate markers of response prediction and evaluation using MRI in the early phases of the disease. Thirty-one treatment-naïve osteosarcoma patients received three cycles of neoadjuvant chemotherapy followed by surgery during 2006-2008. All patients underwent baseline and post-chemotherapy conventional, diffusion-weighted and dynamic contrast-enhanced MRI. Taking histological response (good response ≥90% necrosis) as the reference standard, various parameters of MRI were compared to it. A tumor was considered ellipsoidal; volume, average tumor plane and its relative value (average tumor plane relative/body surface area) was calculated using the standard formula for ellipse. Receiver operating characteristic curves were generated to assess best threshold and predictability. After deriving thresholds for each parameter in univariable analysis, multivariable analysis was carried out. Both pre-and post-chemotherapy absolute and relative-size parameters correlated well with necrosis. Apparent diffusion coefficient did not correlate with necrosis; however, on adjusting for volume, significant correlation was found. Thus, we could derive a new parameter: diffusion per unit volume. In osteosarcoma, chemotherapy response can be predicted and evaluated by conventional and diffusion-weighted MRI early in the disease course and it correlates well with necrosis. Further, newly derived parameter diffusion per unit volume appears to be a sensitive substitute for response evaluation in osteosarcoma.

A Mass Diffusion Model for Dry Snow Utilizing a Fabric Tensor to Characterize Anisotropy

NASA Astrophysics Data System (ADS)

Shertzer, Richard H.; Adams, Edward E.

2018-03-01

A homogenization algorithm for randomly distributed microstructures is applied to develop a mass diffusion model for dry snow. Homogenization is a multiscale approach linking constituent behavior at the microscopic level—among ice and air—to the macroscopic material—snow. Principles of continuum mechanics at the microscopic scale describe water vapor diffusion across an ice grain's surface to the air-filled pore space. Volume averaging and a localization assumption scale up and down, respectively, between microscopic and macroscopic scales. The model yields a mass diffusivity expression at the macroscopic scale that is, in general, a second-order tensor parameterized by both bulk and microstructural variables. The model predicts a mass diffusivity of water vapor through snow that is less than that through air. Mass diffusivity is expected to decrease linearly with ice volume fraction. Potential anisotropy in snow's mass diffusivity is captured due to the tensor representation. The tensor is built from directional data assigned to specific, idealized microstructural features. Such anisotropy has been observed in the field and laboratories in snow morphologies of interest such as weak layers of depth hoar and near-surface facets.

Investigation of Reaction Mechanism on the Lime-Free Roasting of Chromium-Containing Slag

NASA Astrophysics Data System (ADS)

Yu, Kai-ping; Zhang, Hong-ling; Chen, Bo; Xu, Hong-bin; Zhang, Yi

2015-12-01

The lime-free roasting process of trivalent chromium-containing slag was investigated. The effect of Fe and liquid phase on the conversion reaction of chromium was discussed. The oxidation of trivalent chromium depends greatly on the diffusion of Na+ and O2. Both the raw material Na2CO3 and the intermediate product NaFeO2 serve as the carriers of Na+. The Na+ diffusion is improved by the binary liquid phase of Na2CrO4-Na2CO3, whereas excess liquid phase results in a low conversion rate of chromium by hindering the diffusion of oxygen towards the reaction interface. With the increasing of liquid volume, the controlled step of chromium oxidation changes from Na+ diffusion to oxygen diffusion. The mechanism study showed that the volume of liquid phase increased while raising the reaction temperature or prolonging the reaction time. Based on the role of both liquid phase and Fe, the oxidation process of chromium was summarized as a three-stage model: the Na+ diffusion-controlled stage, the O2 diffusion-controlled stage, and the oxidation reaction halted stage.

Serial diffusion-weighted imaging in subacute sclerosing panencephalitis.

PubMed

Kanemura, Hideaki; Aihara, Masao

2008-06-01

Subacute sclerosing panencephalitis may be associated with clinical features of frontal lobe dysfunction. We previously reported that frontal lobe volume falls significantly as clinical stage progresses, using three-dimensional magnetic resonance imaging-based brain volumetry. The hypothesis that frontal volume increases correlate with clinical improvement, however, was not tested in our previous study. Therefore, we reevaluated our patient with subacute sclerosing panencephalitis, to determine whether apparent diffusion coefficient maps can characterize the clinical course of subacute sclerosing panencephalitis. We studied an 8-year-old boy with subacute sclerosing panencephalitis, using serial diffusion-weighted imaging magnetic resonance imaging, and measured the regional apparent diffusion coefficient. The regional apparent diffusion coefficient of the frontal lobe decreased significantly with clinical progression, whereas it increased to within normal range during clinical improvements. The apparent diffusion coefficient of the other regions did not change. These results suggest that the clinical signs of patients with subacute sclerosing panencephalitis are attributable to frontal lobe dysfunction, and that apparent diffusion coefficient measurements may be useful in predicting the clinical course of subacute sclerosing panencephalitis.

Free volumes and gas transport in polymers: amine-modified epoxy resins as a case study.

PubMed

Patil, Pushkar N; Roilo, David; Brusa, Roberto S; Miotello, Antonio; Aghion, Stefano; Ferragut, Rafael; Checchetto, Riccardo

2016-02-07

The CO2 transport process was studied in a series of amine-modified epoxy resins having different cross-linking densities but the same chemical environment for the penetrant molecules. Positron Annihilation Lifetime Spectroscopy (PALS) was used to monitor the free volume structure of the samples and experimentally evaluate their fractional free volume fh(T) and its temperature evolution. The analysis of the free volume hole size distribution showed that all the holes have a size large enough to accommodate the penetrant molecules at temperatures T above the glass transition temperature Tg. The measured gas diffusion constants at T > Tg have been reproduced in the framework of the free volume theory of diffusion using a novel procedure based on the use of fh(T) as an input experimental parameter.

Comprehensive integrated spirometry using raised volume passive and forced expirations and multiple-breath nitrogen washout in infants.

PubMed

Morris, Mohy G

2010-02-28

With the rapid somatic growth and development in infants, simultaneous accurate measurements of lung volume and airway function are essential. Raised volume rapid thoracoabdominal compression (RTC) is widely used to generate forced expiration from an airway opening pressure of 30 cmH(2)O (V(30)). The (dynamic) functional residual capacity (FRC(dyn)) remains the lung volume most routinely measured. The aim of this study was to develop comprehensive integrated spirometry that included all subdivisions of lung volume at V(30) or total lung capacity (TLC(30)). Measurements were performed on 17 healthy infants aged 8.6-119.7 weeks. A commercial system for multiple-breath nitrogen washout (MBNW) to measure lung volumes and a custom made system to perform RTC were used in unison. A refined automated raised volume RTC and the following two novel single maneuvers with dual volume measurements were performed from V(30) during a brief post-hyperventilation apneic pause: (1) the passive expiratory flow was integrated to produce the inspiratory capacity (IC) and the static (passive) FRC (FRC(st)) was estimated by initiating MBNW after end-passive expiration; (2) RTC was initiated late during passive expiration, flow was integrated to produce the slow vital capacity ((j)SVC) and the residual volume (RV) was measured by initiating MBNW after end-expiration while the jacket (j) was inflated. Intrasubject FRC(dyn) and FRC(st) measurements overlapped (p=0.6420) but neither did with the RV (p<0.0001). Means (95% confidence interval) of FRC(dyn), IC, FRC(st), (j)SVC, RV, forced vital capacity and tidal volume were 21.2 (19.7-22.7), 36.7 (33.0-40.4), 21.2 (19.6-22.8), 40.7 (37.2-44.2), 18.1 (16.6-19.7), 40.7 (37.1-44.2) and 10.2 (9.6-10.7)ml/kg, respectively. Static lung volumes and capacities at V(30) and variables from the best forced expiratory flow-volume curve were dependent on age, body length and weight. In conclusion, we developed a comprehensive physiologically integrated approach for in-depth investigation of lung function at V(30) in infants. Copyright 2009 Elsevier B.V. All rights reserved.

Characterization of Polyester Matrix Reinforced with Banana Fibers Thermal Properties by Photoacoustic Technique

NASA Astrophysics Data System (ADS)

de Assis, Foluke S.; Netto, Pedro A.; Margem, Frederico M.; Monteiro, Artur R. P. Junior Sergio N.

Synthetic fibers are being replaced gradually by natural materials such as lignocellulosic fibers. Compared to synthetic fibers, natural fibers have shown advantages in technical aspects such as environmental and economic. So there is a growing international interest in the use of those fibers. The banana fiber presents significant properties to be studied, but until now few thermal properties on banana fiber as reinforcement of polyester matrix were performed. The present work had as its objective to investigate, by photoacoustic spectroscopy and photothermal techniques the thermal properties of diffusivity, specific heat capacity and conductivity for polyester composites reinforced with banana fibers. In the polyester matrix will be added up to 30% in volume of continuous and aligned banana fibers. These values show that the incorporation of banana fibers in the polyester matrix changes its thermal properties.

Early bronchopulmonary involvement in Crohn disease: a case report

PubMed Central

Valletta, Enrico; Bertini, Marina; Sette, Luciano; Braggion, Cesare; Pradal, Ugo; Zannoni, Marina

2001-01-01

Background Bronchopulmonary manifestations of Crohn disease have been rarely described in children, including both subclinical pulmonary involvement and severe lung disease. Case presentation A 6.5-year-old girl is described with early recurrent bronchopulmonary symptoms both at presentation and in the quiescent phase of Crohn disease. Pulmonary function tests (lung volumes and flows, bronchial reactivity and carbon monoxide diffusing capacity) were normal. Bronchoalveolar cytology showed increased (30%) lymphocyte counts and bronchial biopsy revealed thickening of basal membrane and active chronic inflammation. Conclusions Clinical and histological findings in our young patient suggest involvement of both distal and central airways in an early phase of lung disease. The pathogenesis of Crohn disease-associated lung disorders is discussed with reference to the available literature. A low threshold for pulmonary evaluation seems to be advisable in all children with CD. PMID:11734067

Facile synthesis of Fe4N/Fe2O3/Fe/porous N-doped carbon nanosheet as high-performance anode for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Zhang, Dan; Li, Guangshe; Yu, Meijie; Fan, Jianming; Li, Baoyun; Li, Liping

2018-04-01

Iron nitrides are considered as highly promising anode materials for lithium-ion batteries because of their nontoxicity, high abundance, low cost, and higher electrical conductivity. Unfortunately, their limited synthesis routes are available and practical application is still hindered by their fast capacity decay. Herein, a facile and green route is developed to synthesize Fe4N/Fe2O3/Fe/porous N-doped carbon nanosheet composite. The size of Fe4N/Fe2O3/Fe particles is small (10-40 nm) and they are confined in porous N-doped carbon nanosheet. These features are conducive to accommodate volume change well, shorten the diffusion distance and further elevate electrical conductivity. When tested as anode material for lithium-ion batteries, a high discharge capacity of 554 mA h g-1 after 100 cycles at 100 mA g-1 and 389 mA h g-1 after 300 cycles at 1000 mA g-1 are retained. Even at 2000 mA g-1, a high capacity of 330 mA h g-1 can be achieved, demonstrating superior cycling stability and rate performance. New prospects will be brought by this work for the synthesis and the potential application of iron nitrides materials as an anode for LIBs.

A densely packed Sb2O3 nanosheet-graphene aerogel toward advanced sodium-ion batteries.

PubMed

Zhou, Jing; Yan, Bingyi; Yang, Jie; Yang, Yun; Zhou, Wei; Lan, Hao; Wang, Hua; Guo, Lin

2018-05-17

As a promising anodic material for rechargeable batteries, Sb2O3 has drawn increasing attention due to its high theoretical capacity and abundant natural deposits. However, poor cyclability and rate performance of Sb2O3 derived from a large volume change during insertion/desertion reactions as well as a sluggish kinetic process restrict its practical application. Herein, we report a facile amorphous-to-crystalline strategy to synthesize a densely packed Sb2O3 nanosheet-graphene aerogel as a novel anode for sodium ion batteries (SIBs). This Sb2O3/graphene composite displays a reversible capacity as high as 657.9 mA h g-1 even after 100 cycles at 0.1 A g-1, along with an excellent rate capacity of 356.8 mA h g-1 at 5.0 A g-1. The superior electrochemical performance is attributed to the synergistic effects of densely packed Sb2O3 nanosheets and graphene aerogel, which serves as both a robust support and stable buffer layer to maintain the structural stability of the nanocomposite, and enhances the electrode kinetics of electrolyte diffusion and electron transfer simultaneously. Hence, this densely-packed two-dimensional Sb2O3 nanosheet-graphene aerogel can be a promising anode material for rechargeable SIBs due to its facile synthesis process and outstanding electrochemical performance.

Influences of neodymium doping on magnetic and electrochemical properties of Li3V2(PO4)3/C synthesized via a sol-gel method

NASA Astrophysics Data System (ADS)

Liu, Liying; Qiu, Yongbin; Mai, Yongzhi; Wu, Qibai; Zhang, Haiyan

2015-11-01

A series of neodymium doped Li3V2-xNdx(PO4)3/C cathode materials have been successfully synthesized by a citric acid assisted sol-gel method. Nd doped samples (x ≤ 0.10) have well developed monoclinic structure of Li3V2(PO4)3 with enlarged unit cell volume. All samples present typical characteristics of paramagnetism in 4 < T ≤ 300 K, but the magnetic susceptibilities of Nd doped samples increase with Nd content (except for x = 0.15). Nd doped composites show better electrochemical property than that of the undoped one. Among them, the Li3V1.95Nd0.05(PO4)3/C displays the highest capacity and best cycle stability. The Li3V1.95Nd0.05(PO4)3/C presents the first discharge capacity of 129.2 mAh g-1 at 1 C rate in the voltage range of 3.0-4.3 V, 21.7% higher than that of Li3V2(PO4)3/C. And no capacity loss occurs after 100 cycles. The high structural stability, low charge-transfer resistance and rapid Li+ diffusion due to the presence of Nd3+ are mainly responsible for the superior electrochemical performance of Nd doped Li3V2(PO4)3/C cathode materials.

An Isopycnal Box Model with predictive deep-ocean structure for biogeochemical cycling applications

NASA Astrophysics Data System (ADS)

Goodwin, Philip

2012-07-01

To simulate global ocean biogeochemical tracer budgets a model must accurately determine both the volume and surface origins of each water-mass. Water-mass volumes are dynamically linked to the ocean circulation in General Circulation Models, but at the cost of high computational load. In computationally efficient Box Models the water-mass volumes are simply prescribed and do not vary when the circulation transport rates or water mass densities are perturbed. A new computationally efficient Isopycnal Box Model is presented in which the sub-surface box volumes are internally calculated from the prescribed circulation using a diffusive conceptual model of the thermocline, in which upwelling of cold dense water is balanced by a downward diffusion of heat. The volumes of the sub-surface boxes are set so that the density stratification satisfies an assumed link between diapycnal diffusivity, κd, and buoyancy frequency, N: κd = c/(Nα), where c and α are user prescribed parameters. In contrast to conventional Box Models, the volumes of the sub-surface ocean boxes in the Isopycnal Box Model are dynamically linked to circulation, and automatically respond to circulation perturbations. This dynamical link allows an important facet of ocean biogeochemical cycling to be simulated in a highly computationally efficient model framework.

Eliminating the blood-flow confounding effect in intravoxel incoherent motion (IVIM) using the non-negative least square analysis in liver.

PubMed

Gambarota, Giulio; Hitti, Eric; Leporq, Benjamin; Saint-Jalmes, Hervé; Beuf, Olivier

2017-01-01

Tissue perfusion measurements using intravoxel incoherent motion (IVIM) diffusion-MRI are of interest for investigations of liver pathologies. A confounding factor in the perfusion quantification is the partial volume between liver tissue and large blood vessels. The aim of this study was to assess and correct for this partial volume effect in the estimation of the perfusion fraction. MRI experiments were performed at 3 Tesla with a diffusion-MRI sequence at 12 b-values. Diffusion signal decays in liver were analyzed using the non-negative least square (NNLS) method and the biexponential fitting approach. In some voxels, the NNLS analysis yielded a very fast-decaying component that was assigned to partial volume with the blood flowing in large vessels. Partial volume correction was performed by biexponential curve fitting, where the first data point (b = 0 s/mm 2 ) was eliminated in voxels with a very fast-decaying component. Biexponential fitting with partial volume correction yielded parametric maps with perfusion fraction values smaller than biexponential fitting without partial volume correction. The results of the current study indicate that the NNLS analysis in combination with biexponential curve fitting allows to correct for partial volume effects originating from blood flow in IVIM perfusion fraction measurements. Magn Reson Med 77:310-317, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Grain boundary diffusion in olivine (Invited)

NASA Astrophysics Data System (ADS)

Marquardt, K.; Dohmen, R.

2013-12-01

Olivine is the main constituent of Earth's upper mantle. The individual mineral grains are separated by grain boundaries that have very distinct properties compared to those of single crystals and strongly affect large-scale physical and chemical properties of rocks, e.g. viscosity, electrical conductivity and diffusivity. Knowledge on the grain boundary physical and chemical properties, their population and distribution in polycrystalline materials [1] is a prerequisite to understand and model bulk (rock) properties, including their role as pathways for element transport [2] and the potential of grain boundaries as storage sites for incompatible elements [3]. Studies on selected and well characterized single grain boundaries are needed for a detailed understanding of the influence of varying grain boundaries. For instance, the dependence of diffusion on the grain boundary structure (defined by the lattice misfit) and width in silicates is unknown [2, 4], but limited experimental studies in material sciences indicate major effects of grain boundary orientation on diffusion rates. We characterized the effect of grain boundary orientation and temperature on element diffusion in forsterite grain boundaries by transmission electron microscopy (TEM).The site specific TEM-foils were cut using the focused ion beam technique (FIB). To study diffusion we prepared amorphous thin-films of Ni2SiO4 composition perpendicular to the grain boundary using pulsed laser deposition. Annealing (800-1450°C) leads to crystallization of the thin-film and Ni-Mg inter-diffuse into the crystal volume and along the grain boundary. The inter-diffusion profiles were measured using energy dispersive x-ray spectrometry in the TEM, standardized using the Cliff-Lorimer equation and EMPA measurements. We obtain volume diffusion coefficients that are comparable to Ni-Mg inter-diffusion rates in forsterite determined in previous studies at comparable temperatures, with similar activation energies. Grain boundary diffusion perpendicular to the dislocation lines of the small angle grain boundaries proved to be about an order of magnitude faster than volume diffusion, whereas diffusion in high angle grain boundaries is several orders of magnitude faster. We will discuss the variation of element diffusion rates with grain boundary orientation and the temperature- and/or time-induced transition from one diffusion regime to the next regime. This is done using time series experiments and two-dimensional grain boundary diffusion simulations. Finally, we will debate the differences between our data and other data sets that result from different experimental setups, conditions and analyses.

Natural gas storage with activated carbon from a bituminous coal

USGS Publications Warehouse

Sun, Jielun; Rood, M.J.; Rostam-Abadi, M.; Lizzio, A.A.

1996-01-01

Granular activated carbons ( -20 + 100 mesh; 0.149-0.84 mm) were produced by physical activation and chemical activation with KOH from an Illinois bituminous coal (IBC-106) for natural gas storage. The products were characterized by BET surface area, micropore volume, bulk density, and methane adsorption capacities. Volumetric methane adsorption capacities (Vm/Vs) of some of the granular carbons produced by physical activation are about 70 cm3/cm3 which is comparable to that of BPL, a commercial activated carbon. Vm/Vs values above 100 cm3/cm3 are obtainable by grinding the granular products to - 325 mesh (<0.044 mm). The increase in Vm/Vs is due to the increase in bulk density of the carbons. Volumetric methane adsorption capacity increases with increasing pore surface area and micropore volume when normalizing with respect to sample bulk volume. Compared with steam-activated carbons, granular carbons produced by KOH activation have higher micropore volume and higher methane adsorption capacities (g/g). Their volumetric methane adsorption capacities are lower due to their lower bulk densities. Copyright ?? 1996 Elsevier Science Ltd.

Exercise science: research to sustain and enhance performance

NASA Astrophysics Data System (ADS)

Wingo, Jonathan E.

2013-05-01

Cardiovascular adjustments accompanying exercise in high ambient temperatures are likely responsible for diminished aerobic capacity and performance in such conditions. These adjustments include a phenomenon known as cardiovascular drift in which heart rate rises and stroke volume declines progressively over time during constant-rate exercise. A variety of factors modulate the magnitude of cardiovascular drift, e.g., elevated core and skin temperatures, dehydration, and exercise intensity. Regardless of the mode of manipulation, decreases in stroke volume associated with cardiovascular drift result in directionally and proportionally similar decreases in maximal aerobic capacity. Maximal aerobic capacity is determined by maximal heart rate, maximal tissue oxygen extraction, and maximal stroke volume. Because maximal heart rate and maximal tissue oxygen extraction are unaffected during exercise in the heat, decreased stroke volume associated with cardiovascular drift likely persists during maximal efforts and explains the decrease in maximal aerobic capacity. Decreased maximal aerobic capacity results in a greater perceptual and physiological strain accompanying any given level of work. Therefore, sustaining and enhancing performance involves sophisticated monitoring of physiological strain combined with development of countermeasures that mitigate the magnitude of deleterious phenomena like cardiovascular drift.

Bilateral Thalamocortical Abnormalities in Focal Cortical Dysplasia.

PubMed

Rezayev, Arthur; Feldman, Henry A; Levman, Jacob; Takahashi, Emi

2018-05-05

Focal cortical dysplasia (FCD), a congenital malformation of the neocortex and one of the most common causes of medication resistant epilepsy in pediatric populations, can be studied noninvasively by diffusion tensor imaging (DTI). The present study aimed to quantify changes in the thalamus and thalamocortical pathways with respect to fractional anisotropy (FA), apparent diffusion coefficient (ADC), volume, and other common measures. The study quantified data collected from pediatric patients with a prior diagnosis of FCD; 75 patients (35 females, 10.1 ± 6.5 years) for analysis of thalamic volume and 68 patients (32 females, 10.2 ± 6.4 years) for DTI analysis. DTI scans were taken at 3 Tesla MRI scanners (30 diffusion gradient directions; b= 1000 s/mm 2 and 5 non diffusion-weighted measurements). DTI tractography was performed using the FACT algorithm with an angle threshold of 45 degrees. Manually delineated ROIs were used to compare the hemisphere containing the dysplasia to the contralateral hemisphere and controls. A significant decrease in the volume of the FCD hemisphere thalamus was detected as compared to the contralateral hemisphere. In comparison to controls, there was an observed reduction in tract volume, length, count, FA of thalami, and FA of thalamocortical pathways in FCD patients. FCD patients had higher odds of exhibiting high ADC in both the thalamus and thalamocortical pathways. The data implied a widespread reduction in structural connectivity of the thalamocortical network. MRI analysis suggests a potential influence of FCD on thalamic volume. Copyright © 2018. Published by Elsevier B.V.

Determination of the Temperature Dependence of Heat Capacity for Some Molecular Crystals of Nitro Compounds

NASA Astrophysics Data System (ADS)

Kovalev, Yu. M.; Kuropatenko, V. F.

2018-05-01

An analysis of the existing approximations used for describing the dependence of heat capacity at a constant volume on the temperature of a molecular crystal has been carried out. It is shown that the considered Debye and Einstein approximations do not enable one to adequately describe the dependence of heat capacity at a constant volume on the temperature of the molecular crystals of nitro compounds. This inference requires the development of special approximations that would describe both low-frequency and high-frequency parts of the vibrational spectra of molecular crystals. This work presents a universal dependence allowing one to describe the dependence of heat capacity at a constant volume on temperature for a number of molecular crystals of nitro compounds.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dubey, P., E-mail: purushd@barc.gov.in; Sharma, V. K.; Mitra, S.

Synthetic hydroxyapatite (HAp) is an important material in biomedical engineering due to its excellent biocompatibility and bioactivity. Here we report dynamics of cetyltrimethylammonium bromide (CTAB) in HAp composite, prepared by co-precipitation method, as studied by quasielastic neutron scattering (QENS) technique. It is found that the observed dynamics involved two time scales associated with fast torsional motion and segmental motion of the CTAB monomers. In addition to segmental motion of the hydrogen atoms, few undergo torsional motion as well. Torsional dynamics was described by a 2-fold jump diffusion model. The segmental dynamics of CTAB has been described assumimg the hydrogen atomsmore » undergoing diffusion inside a sphere of confined volume. While the diffusivity is found to increase with temperature, the spherical volumes within which the hydrogen atoms are undergoing diffusion remain almost unchanged.« less

Step - wise transient method - Influence of heat source inertia

NASA Astrophysics Data System (ADS)

Malinarič, Svetozár; Dieška, Peter

2016-07-01

Step-wise transient (SWT) method is an experimental technique for measuring the thermal diffusivity and conductivity of materials. Theoretical models and experimental apparatus are presented and the influence of the heat source capacity are investigated using the experiment simulation. The specimens from low density polyethylene (LDPE) were measured yielding the thermal diffusivity 0.165 mm2/s and thermal conductivity 0.351 W/mK with the coefficient of variation less than 1.4 %. The heat source capacity caused the systematic error of the results smaller than 1 %.

Development of Sediment Deposition Height Capacity Equation in Sewer Networks

NASA Astrophysics Data System (ADS)

Song, Yangho; Jo, Deokjun; Lee, Jungho

2017-04-01

Sediment characteristics and transport processes in sewers are markedly different from river. There is a wide range of particle densities and smaller particle size variation in sewers. Sediment supply and the available erodible material are more limited in sewers, and the diverse hydraulic characteristics in sewer systems are more unsteady. Prevention of sewer sediment accumulation, which can cause major sewer operational problems, is imperative and has been an immense concern for engineers. The effects of sediment formation in sewer systems, an appropriate sediment transport modelling with the ability to determine the location and depth of sediment deposit is needed. It is necessary to design efficiently considering the transfer and settling phenomena of the sediment coming into the sewer systems. During transport in the sewer, the minimum shear flow velocity and possible shear stress at which the sediment is transported smoothly. However, the interaction of sediment and fluid within the sewer systems has been very complex and the rigorous theoretical handling of this problem has not been developed. It is derived from the empirical values obtained from the river bed. The basic theory that particles float is based on the balance between sedimentation of particles by gravity and turbulent diffusion of fluids. There are many variables related. Representative parameters include complex phenomena due to collisions between particles, particles and fluids, and interactions between particles and tube walls. In general, the main parameters that form the boundary between the main transport and sediment are particle size, density, volume fraction, pipe diameter and gravity. As the particle size and volume concentration increase, the minimum feed rate increases and the same tendency is observed for the change of the capillary diameter. Based on this tendency, this study has developed a sediment deposition height capacity formula to take into consideration the sewer discharge capacity. The main objective in undertaking this research is the assessment of the sediment scouring and transporting capacity of the discharged. Acknowledgements This research was supported by a grant(13AWMP-B066744-01) from Advanced Water Management Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government.

An improved procedure for reconstitution of the uncoupling protein and in-depth analysis of H+/OH- transport.

PubMed

Winkler, E; Klingenberg, M

1992-07-01

An improved procedure for reincorporation of isolated uncoupling protein (UCP) from brown adipose tissue into phospholipid vesicles is reported and H+ uptake in K(+)-driven exchange diffusion quantitatively analyzed. UCP is isolated and reconstituted with medium-length linear-chain alkyl polyoxyethylene. In the critical step of vesicle formation, the stepwise removal of the detergent by polystyrene beads is applied. Vesicles are generated in the presence of solutes and buffers to be internalized which are then removed by gel filtration. The internal volume is about 4 microliters/mg phospholipid with a vesicle diameter of 100 nm. One vesicle contains, on average, six molecules UCP. The best results are obtained with purified egg yolk phosphatidylcholine. Addition of PtdEtn, PtdSer decreases the vesicle size and, still more, H(+)-transport activity by UCP. Asolectin completely inactivates UCP. K(+)-gradient-driven H+ uptake is 80% inhibited by external GTP and 95% by internal plus external GTP. When H+ transport is recorded externally by a pH electrode and internally by pyranine, the kinetics show no delay resulting from intervening membrane-bound H+ pools. Total H+ uptake after addition of carbonylcyanine m-chlorophenylhydrazone (CCCP) and valinomycin corresponds to the diffusion between H+ and K+ and is unchanged by GTP. The linear correlation of H(+)-transport inhibition to GTP binding demonstrates that all UCP molecules incorporated are equally active. The exchange diffusion between H+ uptake and K+ efflux is demonstrated using a K+ electrode and 86Rb measurements. Recording delta psi using 3,3'-diispropylthiadicarbocyanine shows a rapid generation of delta psi on valinomycin addition, which decreases only slightly with H+ uptake, even after addition of CCCP or gramicidin. The delta psi collapses only after addition of external K+. By demonstrating that valinomycin-induced K+ and H+ fluxes reflect relaxation into the diffusion equilibrium state, the transport rate of UCP can be evaluated as a first-order rate, VH+/CH+, in which the rate, VH+, is related to H(+)-uptake capacity, CH+. This allows quantitative comparison of transport rates independently of the variable CH+. The dependence on delta psi of H+ transport is measured by varying external K+ concentration. A virtually linear relation of the rate to the K(+)-diffusion potential is observed, although the capacity is only slightly changed. The linear VH+/delta psi relationship resembles an open-channel type of transport, but is discussed in terms of a low-activation-barrier type of carrier mechanism, in contrast to the log (VH+/delta psi) relation found for the ADP/ATP carrier with high activation barriers.

Specific storage volumes: A useful tool for CO2 storage capacity assessment

USGS Publications Warehouse

Brennan, S.T.; Burruss, R.C.

2006-01-01

Subsurface geologic strata have the potential to store billions of tons of anthropogenic CO2; therefore, geologic carbon sequestration can be an effective mitigation tool used to slow the rate at which levels of atmospheric CO2 are increasing. Oil and gas reservoirs, coal beds, and saline reservoirs can be used for CO2 storage; however, it is difficult to assess and compare the relative storage capacities of these different settings. Typically, CO2 emissions are reported in units of mass, which are not directly applicable to comparing the CO2 storage capacities of the various storage targets. However, if the emission values are recalculated to volumes per unit mass (specific volume) then the volumes of geologic reservoirs necessary to store CO2 emissions from large point sources can be estimated. The factors necessary to convert the mass of CO2 emissions to geologic storage volume (referred to here as Specific Storage Volume or 'SSV') can be reported in units of cubic meters, cubic feet, and petroleum barrels. The SSVs can be used to estimate the reservoir volume needed to store CO2 produced over the lifetime of an individual point source, and to identify CO2 storage targets of sufficient size to meet the demand from that given point source. These storage volumes also can then be projected onto the land surface to outline a representative "footprint," which marks the areal extent of storage. This footprint can be compared with the terrestrial carbon sequestration capacity of the same land area. The overall utility of this application is that the total storage capacity of any given parcel of land (from surface to basement) can be determined, and may assist in making land management decisions. ?? Springer Science+Business Media, LLC 2006.

NEEDED RESEARCH ON DIFFUSION WITHIN EDUCATIONAL ORGANIZATIONS.

ERIC Educational Resources Information Center

JAIN, NEMI C.; ROGERS, EVERETT M.

IN SPITE OF THE VOLUME OF RESEARCH ATTENTION DEVOTED TO THE DIFFUSION OF INNOVATIONS, RELATIVELY LITTLE EMPHASIS HAS BEEN PLACED UPON DIFFUSION WITHIN ORGANIZATIONAL STRUCTURES. METHODOLOGICALLY, RELATIONAL ANALYSIS IN WHICH THE UNIT OF ANALYSIS IS A TWO-PERSON INTERACTING PAIR, A MULTIPLE PERSON COMMUNICATION CHAIN, OR CLIQUES OR SUBSYSTEMS IS…

Diffusion in jammed particle packs

NASA Astrophysics Data System (ADS)

Bolintineanu, Dan S.; Silbert, Leonardo E.; Grest, Gary S.; Lechman, Jeremy B.

2015-03-01

Diffusive transport in jammed particle packs is of interest for a number of applications, as well as being a potential indicator of structural properties near the jamming point. To this end, we report stochastic simulations of equilibrium diffusion through monodisperse sphere packs near the jamming point in the limit of a perfectly insulating surrounding medium. The time dependence of various diffusion properties is resolved over several orders of magnitude. Two time regimes of expected Fickian diffusion are observed, separated by an intermediate regime of anomalous diffusion. This intermediate regime grows as the particle volume fraction approaches the critical jamming transition. The diffusion behavior is fully controlled by the extent of the contacts between neighboring particles, which in turn depend on proximity to the jamming point. In particular, the mean first passage time associated with the escape of random walkers between neighboring particles is shown to control both the time to recover Fickian diffusion and the long time diffusivity. Scaling laws are established that relate these quantities to the difference between the actual and critical jamming volume fractions. Sandia National Laboratories is a multiprogram laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's NNSA under Contract DE- AC04-94AL85000.

An Order Insertion Scheduling Model of Logistics Service Supply Chain Considering Capacity and Time Factors

PubMed Central

Yang, Yi; Wang, Shuqing; Liu, Yang

2014-01-01

Order insertion often occurs in the scheduling process of logistics service supply chain (LSSC), which disturbs normal time scheduling especially in the environment of mass customization logistics service. This study analyses order similarity coefficient and order insertion operation process and then establishes an order insertion scheduling model of LSSC with service capacity and time factors considered. This model aims to minimize the average unit volume operation cost of logistics service integrator and maximize the average satisfaction degree of functional logistics service providers. In order to verify the viability and effectiveness of our model, a specific example is numerically analyzed. Some interesting conclusions are obtained. First, along with the increase of completion time delay coefficient permitted by customers, the possible inserting order volume first increases and then trends to be stable. Second, supply chain performance reaches the best when the volume of inserting order is equal to the surplus volume of the normal operation capacity in mass service process. Third, the larger the normal operation capacity in mass service process is, the bigger the possible inserting order's volume will be. Moreover, compared to increasing the completion time delay coefficient, improving the normal operation capacity of mass service process is more useful. PMID:25276851

A Framework for Linear and Non-Linear Registration of Diffusion-Weighted MRIs Using Angular Interpolation

PubMed Central

Duarte-Carvajalino, Julio M.; Sapiro, Guillermo; Harel, Noam; Lenglet, Christophe

2013-01-01

Registration of diffusion-weighted magnetic resonance images (DW-MRIs) is a key step for population studies, or construction of brain atlases, among other important tasks. Given the high dimensionality of the data, registration is usually performed by relying on scalar representative images, such as the fractional anisotropy (FA) and non-diffusion-weighted (b0) images, thereby ignoring much of the directional information conveyed by DW-MR datasets itself. Alternatively, model-based registration algorithms have been proposed to exploit information on the preferred fiber orientation(s) at each voxel. Models such as the diffusion tensor or orientation distribution function (ODF) have been used for this purpose. Tensor-based registration methods rely on a model that does not completely capture the information contained in DW-MRIs, and largely depends on the accurate estimation of tensors. ODF-based approaches are more recent and computationally challenging, but also better describe complex fiber configurations thereby potentially improving the accuracy of DW-MRI registration. A new algorithm based on angular interpolation of the diffusion-weighted volumes was proposed for affine registration, and does not rely on any specific local diffusion model. In this work, we first extensively compare the performance of registration algorithms based on (i) angular interpolation, (ii) non-diffusion-weighted scalar volume (b0), and (iii) diffusion tensor image (DTI). Moreover, we generalize the concept of angular interpolation (AI) to non-linear image registration, and implement it in the FMRIB Software Library (FSL). We demonstrate that AI registration of DW-MRIs is a powerful alternative to volume and tensor-based approaches. In particular, we show that AI improves the registration accuracy in many cases over existing state-of-the-art algorithms, while providing registered raw DW-MRI data, which can be used for any subsequent analysis. PMID:23596381

A Framework for Linear and Non-Linear Registration of Diffusion-Weighted MRIs Using Angular Interpolation.

PubMed

Duarte-Carvajalino, Julio M; Sapiro, Guillermo; Harel, Noam; Lenglet, Christophe

2013-01-01

Registration of diffusion-weighted magnetic resonance images (DW-MRIs) is a key step for population studies, or construction of brain atlases, among other important tasks. Given the high dimensionality of the data, registration is usually performed by relying on scalar representative images, such as the fractional anisotropy (FA) and non-diffusion-weighted (b0) images, thereby ignoring much of the directional information conveyed by DW-MR datasets itself. Alternatively, model-based registration algorithms have been proposed to exploit information on the preferred fiber orientation(s) at each voxel. Models such as the diffusion tensor or orientation distribution function (ODF) have been used for this purpose. Tensor-based registration methods rely on a model that does not completely capture the information contained in DW-MRIs, and largely depends on the accurate estimation of tensors. ODF-based approaches are more recent and computationally challenging, but also better describe complex fiber configurations thereby potentially improving the accuracy of DW-MRI registration. A new algorithm based on angular interpolation of the diffusion-weighted volumes was proposed for affine registration, and does not rely on any specific local diffusion model. In this work, we first extensively compare the performance of registration algorithms based on (i) angular interpolation, (ii) non-diffusion-weighted scalar volume (b0), and (iii) diffusion tensor image (DTI). Moreover, we generalize the concept of angular interpolation (AI) to non-linear image registration, and implement it in the FMRIB Software Library (FSL). We demonstrate that AI registration of DW-MRIs is a powerful alternative to volume and tensor-based approaches. In particular, we show that AI improves the registration accuracy in many cases over existing state-of-the-art algorithms, while providing registered raw DW-MRI data, which can be used for any subsequent analysis.

Prediction of nanofluids properties: the density and the heat capacity

NASA Astrophysics Data System (ADS)

Zhelezny, V. P.; Motovoy, I. V.; Ustyuzhanin, E. E.

2017-11-01

The results given in this report show that the additives of Al2O3 nanoparticles lead to increase the density and decrease the heat capacity of isopropanol. Based on the experimental data the excess molar volume and the excess molar heat capacity were calculated. The report suggests new method for predicting the molar volume and molar heat capacity of nanofluids. It is established that the values of the excess thermodynamic functions are determined by the properties and the volume of the structurally oriented layers of the base fluid molecules near the surface of nanoparticles. The heat capacity of the structurally oriented layers of the base fluid is less than the heat capacity of the base fluid for given parameters due to the greater regulation of its structure. It is shown that information on the geometric dimensions of the structured layers of the base fluid near nanoparticles can be obtained from data on the nanofluids density and at ambient temperature - by the dynamic light scattering method. For calculations of the nanofluids heat capacity over a wide range of temperatures a new correlation based on the extended scaling is proposed.

Isotherm and kinetic studies on adsorption of oil sands process-affected water organic compounds using granular activated carbon.

PubMed

Islam, Md Shahinoor; McPhedran, Kerry N; Messele, Selamawit A; Liu, Yang; Gamal El-Din, Mohamed

2018-07-01

The production of oil from oil sands in northern Alberta has led to the generation of large volumes of oil sands process-affected water (OSPW) that was reported to be toxic to aquatic and other living organisms. The toxicity of OSPW has been attributed to the complex nature of OSPW matrix including the inorganic and organic compounds primarily naphthenic acids (NAs: C n H 2n+Z O x ). In the present study, granular activated carbon (GAC) adsorption was investigated for its potential use to treat raw and ozonated OSPW. The results indicated that NA species removal increased with carbon number (n) for a fixed Z number; however, the NA species removal decreased with Z number for a fixed carbon number. The maximum adsorption capacities obtained from Langmuir adsorption isotherm based on acid-extractable fraction (AEF) and NAs were 98.5 mg and 60.9 mg AEF/g GAC and 60 mg and 37 mg NA/g GAC for raw and ozonated OSPW, respectively. It was found that the Freundlich isotherm model best fits the AEF and NA equilibrium data (r 2  ≥ 0.88). The adsorption kinetics showed that the pseudo-second order and intraparticle diffusion models were both appropriate in modeling the adsorption kinetics of AEF and NAs to GAC (r 2  ≥ 0.97). Although pore diffusion was the rate limiting step, film diffusion was still significant for assessing the rate of diffusion of NAs. This study could be helpful to model, design and optimize the adsorption treatment technologies of OSPW and to assess the performance of other adsorbents. Copyright © 2018 Elsevier Ltd. All rights reserved.

Integrating 3D Flower-Like Hierarchical Cu2NiSnS4 with Reduced Graphene Oxide as Advanced Anode Materials for Na-Ion Batteries.

PubMed

Yuan, Shuang; Wang, Sai; Li, Lin; Zhu, Yun-hai; Zhang, Xin-bo; Yan, Jun-min

2016-04-13

Development of an anode material with high performance and low cost is crucial for implementation of next-generation Na-ion batteries (NIBs) electrode, which is proposed to meet the challenges of large scale renewable energy storage. Metal chalcogenides are considered as promising anode materials for NIBs due to their high theoretical capacity, low cost, and abundant sources. Unfortunately, their practical application in NIBs is still hindered because of low conductivity and morphological collapse caused by their volume expansion and shrinkage during Na(+) intercalation/deintercalation. To solve the daunting challenges, herein, we fabricated novel three-dimensional (3D) Cu2NiSnS4 nanoflowers (CNTSNs) as a proof-of-concept experiment using a facile and low-cost method. Furthermore, homogeneous integration with reduced graphene oxide nanosheets (RGNs) endows intrinsically insulated CNTSNs with superior electrochemical performances, including high specific capacity (up to 837 mAh g(-1)), good rate capability, and long cycling stability, which could be attributed to the unique 3D hierarchical structure providing fast ion diffusion pathway and high contact area at the electrode/electrolyte interface.

Changes in Pulmonary Function After Stereotactic Body Radiotherapy and After Surgery for Stage I and II Non-small Cell Lung Cancer, a Description of Two Cohorts.

PubMed

Alberts, Leonie; El Sharouni, Sherif Y; Hofman, Frederik N; Van Putte, Bart P; Tromp, Ellen; Van Vulpen, Marco; Kastelijn, Elisabeth A; Schramel, Franz M N H

2015-12-01

To evaluate changes in pulmonary function tests (PFTs) at different follow-up durations after stereotactic body radiotherapy (SBRT) and surgery in stage I and II non-small-cell lung cancer (NSCLC). Differences between pre-treatment- and follow-up PFTs were analyzed in 93 patients treated with surgery and 30 patients treated with SBRT for NSCLC. Follow-up durations were categorized into: early (0-9 months), middle (10-21 months) and late (≥22 months). Wilcoxon signed-rank test was used to analyze differences between pre-treatment and follow-up PFTs. Forced expiratory volume in one second, forced vital capacity and diffusion capacity for carbon monoxide corrected for the actual hemoglobin level significantly diminished after surgery for all follow-up durations: 11-17% of predicted values. After SBRT, PFTs remained stable, but a declining trend of 6% (p=0.1) was observed after 22 months. SBRT might lead to less treatment-related toxicity measured by PFTs than surgery in both the short and long term. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Hierarchically-structured hollow NiO nanospheres/nitrogen-doped graphene hybrid with superior capacity retention and enhanced rate capability for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Chen, Jiayuan; Wu, Xiaofeng; Liu, Ya; Gong, Yan; Wang, Pengfei; Li, Wenhui; Mo, Shengpeng; Tan, Qiangqiang; Chen, Yunfa

2017-12-01

A facile template-free synthesis strategy is demonstrated to fabricate nanostructured NiO/N-doped graphene hybrid, in which NiO hollow nanospheres with hierarchically mesoporous structure are tightly anchored on N-doped graphene matrix. The mesoporous shell of NiO can not only provide sufficient electrode/electrolyte contact areas to accelerate ion diffusion and electron exchange, but also efficiently mitigate the volume change that occurs during long-time reactions. Simultaneously, the reduced graphene oxide with doping nitrogen atoms are employed as effectively conductive backbone, further enhancing the electrochemical performances. When used as anodic material for lithium ion batteries, the synergistic system delivers a reversible capacity up to 1104.6 mAh g-1 after 150 cycles at a current density of 0.08 A g-1 and 422.3 mAh g-1 at a high charging rate of 4 A g-1, which is better than those of the bare counterparts and most other NiO-based materials reported in the previous literatures. The hierarchically hollow NiO nanostructure combined with N-doped graphene matrix provides a promising candidate applied in advanced anode materials for lithium ion batteries.

Transient Nonequilibrium Molecular Dynamic Simulations of Thermal Conductivity: 1. Simple Fluids

NASA Astrophysics Data System (ADS)

Hulse, R. J.; Rowley, R. L.; Wilding, W. V.

2005-01-01

Thermal conductivity has been previously obtained from molecular dynamics (MD) simulations using either equilibrium (EMD) simulations (from Green--Kubo equations) or from steady-state nonequilibrium (NEMD) simulations. In the case of NEMD, either boundary-driven steady states are simulated or constrained equations of motion are used to obtain steady-state heat transfer rates. Like their experimental counterparts, these nonequilibrium steady-state methods are time consuming and may have convection problems. Here we report a new transient method developed to provide accurate thermal conductivity predictions from MD simulations. In the proposed MD method, molecules that lie within a specified volume are instantaneously heated. The temperature decay of the system of molecules inside the heated volume is compared to the solution of the transient energy equation, and the thermal diffusivity is regressed. Since the density of the fluid is set in the simulation, only the isochoric heat capacity is needed in order to obtain the thermal conductivity. In this study the isochoric heat capacity is determined from energy fluctuations within the simulated fluid. The method is valid in the liquid, vapor, and critical regions. Simulated values for the thermal conductivity of a Lennard-Jones (LJ) fluid were obtained using this new method over a temperature range of 90 to 900 K and a density range of 1-35 kmol · m-3. These values compare favorably with experimental values for argon. The new method has a precision of ±10%. Compared to other methods, the algorithm is quick, easy to code, and applicable to small systems, making the simulations very efficient.

Novel Assessment of Interstitial Lung Disease Using the "Computer-Aided Lung Informatics for Pathology Evaluation and Rating" (CALIPER) Software System in Idiopathic Inflammatory Myopathies.

PubMed

Ungprasert, Patompong; Wilton, Katelynn M; Ernste, Floranne C; Kalra, Sanjay; Crowson, Cynthia S; Rajagopalan, Srinivasan; Bartholmai, Brian J

2017-10-01

To evaluate the correlation between measurements from quantitative thoracic high-resolution CT (HRCT) analysis with "Computer-Aided Lung Informatics for Pathology Evaluation and Rating" (CALIPER) software and measurements from pulmonary function tests (PFTs) in patients with idiopathic inflammatory myopathies (IIM)-associated interstitial lung disease (ILD). A cohort of patients with IIM-associated ILD seen at Mayo Clinic was identified from medical record review. Retrospective analysis of HRCT data and PFTs at baseline and 1 year was performed. The abnormalities in HRCT were quantified using CALIPER software. A total of 110 patients were identified. At baseline, total interstitial abnormalities as measured by CALIPER, both by absolute volume and by percentage of total lung volume, had a significant negative correlation with diffusing capacity for carbon monoxide (DLCO), total lung capacity (TLC), and oxygen saturation. Analysis by subtype of interstitial abnormality revealed significant negative correlations between ground glass opacities (GGO) and reticular density (RD) with DLCO and TLC. At one year, changes of total interstitial abnormalities compared with baseline had a significant negative correlation with changes of TLC and oxygen saturation. A negative correlation between changes of total interstitial abnormalities and DLCO was also observed, but it was not statistically significant. Analysis by subtype of interstitial abnormality revealed negative correlations between changes of GGO and RD and changes of DLCO, TLC, and oxygen saturation, but most of the correlations did not achieve statistical significance. CALIPER measurements correlate well with functional measurements in patients with IIM-associated ILD.

Estimation of regional gas and tissue volumes of the lung in supine man using computed tomography.

PubMed

Denison, D M; Morgan, M D; Millar, A B

1986-08-01

This study was intended to discover how well computed tomography could recover the volume and weight of lung like foams in a body like shell, and then how well it could recover the volume and weight of the lungs in supine man. Model thoraces were made with various loaves of bread submerged in water. Computed tomography scans recovered the volume of the model lungs (true volume range 250-12,500 ml) within +0.2 (SD 68) ml and their weights (true range 72-3125 g) within +30 (78) g. Scans also recovered successive injections of 50 ml of water, within +/- 5 ml. Scans in 12 healthy supine men recovered their vital capacities, total lung capacities (TLC), and predicted tissue volumes with comparable accuracy. At total lung capacity the mean tissue volume of single lungs was 431 (64) ml and at residual volume (RV) it was 427 (63) ml. Tissue volume was then used to match inspiratory and expiratory slices and calculate regional ventilation. Throughout the mid 90% of lung the RV/TLC ratio was fairly constant--mean 21% (5%). New methods of presenting such regional data graphically and automatically are also described.

Thermal diffusion behavior of hard-sphere suspensions.

PubMed

Ning, Hui; Buitenhuis, Johan; Dhont, Jan K G; Wiegand, Simone

2006-11-28

We studied the thermal diffusion behavior of octadecyl coated silica particles (R(h)=27 nm) in toluene between 15.0 and 50.0 degrees C in a volume fraction range of 1%-30% by means of thermal diffusion forced Rayleigh scattering. The colloidal particles behave like hard spheres at high temperatures and as sticky spheres at low temperatures. With increasing temperature, the obtained Soret coefficient S(T) of the silica particles changed sign from negative to positive, which implies that the colloidal particles move to the warm side at low temperatures, whereas they move to the cold side at high temperatures. Additionally, we observed also a sign change of the Soret coefficient from positive to negative with increasing volume fraction. This is the first colloidal system for which a sign change with temperature and volume fraction has been observed. The concentration dependence of the thermal diffusion coefficient of the colloidal spheres is related to the colloid-colloid interactions, and will be compared with an existing theoretical description for interacting spherical particles. To characterize the particle-particle interaction parameters, we performed static and dynamic light scattering experiments. The temperature dependence of the thermal diffusion coefficient is predominantly determined by single colloidal particle properties, which are related to colloid-solvent molecule interactions.

Early life predictors of brain development at term-equivalent age in infants born across the gestational age spectrum.

PubMed

Thompson, Deanne K; Kelly, Claire E; Chen, Jian; Beare, Richard; Alexander, Bonnie; Seal, Marc L; Lee, Katherine; Matthews, Lillian G; Anderson, Peter J; Doyle, Lex W; Spittle, Alicia J; Cheong, Jeanie L Y

2018-04-13

It is well established that preterm infants have altered brain development compared with full-term (FT; ≥37 weeks' gestational age [GA]) infants, however the perinatal factors associated with brain development in preterm infants have not been fully elucidated. In particular, perinatal predictors of brain development may differ between very preterm infants (VP; <32 weeks' GA) and infants born moderate (MP; 32-33 weeks' GA) and late (LP; 34-36 weeks' GA) preterm, but this has not been studied. This study aimed to investigate the effects of early life predictors on brain volume and microstructure at term-equivalent age (TEA; 38-44 weeks), and whether these effects differ for GA groups (VP, MP, LP or FT). Structural images from 328 infants (91 VP, 63 MP, 104 LP and 70 FT) were segmented into white matter, cortical grey matter, cerebrospinal fluid, subcortical grey matter, brainstem and cerebellum. Cortical grey matter and white matter images were analysed using voxel-based morphometry. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) images from 361 infants (92 VP, 69 MP, 120 LP and 80 FT) were analysed using Tract-Based Spatial Statistics. Relationships between early life predictors (birthweight standard deviation score [BWSDS], multiple birth, sex, postnatal growth and social risk) and global brain volumes were analysed using linear regressions. Relationships between early life predictors and regional brain volumes and diffusion measures were analysed using voxelwise non-parametric permutation testing. Male sex was associated with higher global volumes of all tissues and higher regional volumes throughout much of the cortical grey matter and white matter, particularly in the FT group. Male sex was also associated with lower FA and higher AD, RD and MD in the optic radiation, external and internal capsules and corona radiata, and these associations were generally similar between GA groups. Higher BWSDS was associated with higher global volumes of all tissues and higher regional volumes in much of the cortical grey matter and white matter in all GA groups, as well as higher FA and lower RD and MD in many major tracts (corpus callosum, optic radiation, internal and external capsules and corona radiata), particularly in the MP and LP groups. Multiple birth and social risk also showed associations with global and regional volumes and regional diffusion values which varied by GA group, but these associations were not independent of the other early life predictors. Postnatal growth was not associated with brain volumes or diffusion values. Early life predictors of brain volumes and microstructure at TEA include sex, BWSDS, multiple birth and social risk, which have different effects based on GA group at birth. This study improves knowledge of the perinatal factors associated with brain abnormalities in infants born across the prematurity spectrum. Copyright © 2018. Published by Elsevier Inc.

A coupling strategy for nonlocal and local diffusion models with mixed volume constraints and boundary conditions

DOE PAGES

D'Elia, Marta; Perego, Mauro; Bochev, Pavel B.; ...

2015-12-21

We develop and analyze an optimization-based method for the coupling of nonlocal and local diffusion problems with mixed volume constraints and boundary conditions. The approach formulates the coupling as a control problem where the states are the solutions of the nonlocal and local equations, the objective is to minimize their mismatch on the overlap of the nonlocal and local domains, and the controls are virtual volume constraints and boundary conditions. When some assumptions on the kernel functions hold, we prove that the resulting optimization problem is well-posed and discuss its implementation using Sandia’s agile software components toolkit. As a result,more » the latter provides the groundwork for the development of engineering analysis tools, while numerical results for nonlocal diffusion in three-dimensions illustrate key properties of the optimization-based coupling method.« less

A Hough Transform Global Probabilistic Approach to Multiple-Subject Diffusion MRI Tractography

PubMed Central

Aganj, Iman; Lenglet, Christophe; Jahanshad, Neda; Yacoub, Essa; Harel, Noam; Thompson, Paul M.; Sapiro, Guillermo

2011-01-01

A global probabilistic fiber tracking approach based on the voting process provided by the Hough transform is introduced in this work. The proposed framework tests candidate 3D curves in the volume, assigning to each one a score computed from the diffusion images, and then selects the curves with the highest scores as the potential anatomical connections. The algorithm avoids local minima by performing an exhaustive search at the desired resolution. The technique is easily extended to multiple subjects, considering a single representative volume where the registered high-angular resolution diffusion images (HARDI) from all the subjects are non-linearly combined, thereby obtaining population-representative tracts. The tractography algorithm is run only once for the multiple subjects, and no tract alignment is necessary. We present experimental results on HARDI volumes, ranging from simulated and 1.5T physical phantoms to 7T and 4T human brain and 7T monkey brain datasets. PMID:21376655

Two-way coupled SPH and particle level set fluid simulation.

PubMed

Losasso, Frank; Talton, Jerry; Kwatra, Nipun; Fedkiw, Ronald

2008-01-01

Grid-based methods have difficulty resolving features on or below the scale of the underlying grid. Although adaptive methods (e.g. RLE, octrees) can alleviate this to some degree, separate techniques are still required for simulating small-scale phenomena such as spray and foam, especially since these more diffuse materials typically behave quite differently than their denser counterparts. In this paper, we propose a two-way coupled simulation framework that uses the particle level set method to efficiently model dense liquid volumes and a smoothed particle hydrodynamics (SPH) method to simulate diffuse regions such as sprays. Our novel SPH method allows us to simulate both dense and diffuse water volumes, fully incorporates the particles that are automatically generated by the particle level set method in under-resolved regions, and allows for two way mixing between dense SPH volumes and grid-based liquid representations.

Diffusion of 4-methyl-pent-3-en-2-one (1); air (2)

NASA Astrophysics Data System (ADS)

Winkelmann, J.

This document is part of Subvolume A `Gases in Gases, Liquids and their Mixtures' of Volume 15 `Diffusion in Gases, Liquids and Electrolytes' of Landolt-Börnstein Group IV `Physical Chemistry'. It is part of the chapter of the chapter `Diffusion in Pure Gases' and contains data on diffusion of (1) 4-methyl-pent-3-en-2-one; (2) air

Pulmonary manifestations of anti-ARS antibody positive interstitial pneumonia--with or without PM/DM.

PubMed

Takato, Hazuki; Waseda, Yuko; Watanabe, Satoshi; Inuzuka, Kanako; Katayama, Nobuyuki; Ichikawa, Yukari; Yasui, Masahide; Fujimura, Masaki

2013-01-01

Autoantibodies against aminoacyl-tRNA synthetases (ARS) have been found to be highly specific for polymyositis and dermatomyositis (PM/DM) and to correlate strongly with complicating interstitial pneumonia (IP). The aim of the present study was to compare the clinical presentations of anti-ARS antibody-positive IP patients with or without manifestations of PM/DM. We retrospectively examined 36 IP patients with anti-ARS antibodies. Sixteen patients presented with and 20 without the features of PM/DM. They were divided into PM/DM-IP and idiopathic-IP (IIP) groups. Clinical symptoms, findings on physical examination, laboratory data, pulmonary function, computed tomography (CT), and bronchoalveolar lavage fluid (BALF) cell counts were compared. Skin findings, myalgia, and elevation of serum creatinine kinase were found in the PM/DM-IP group. Features common to both groups included: volume loss in lower bilateral lobes; ground-glass opacities, reticular shadows and traction bronchiectasis on chest CT; high percentage of lymphocytes (IIP: 44.0% ± 21.0% (mean ± SD), PM/DM-IP: 50.5% ± 23.5%) and low CD4/8 ratios (IIP: 0.36 ± 0.34, PM/DM-IP: 0.44 ± 0.42) in BALF; decreased pulmonary function, including percentage of predicted vital capacity (VC) (IIP: 80.1% ± 15.4%, PM/DM-IP: 73.6% ± 16.4%), residual volume (RV) (IIP: 70.7% ± 21.7%, PM/DM-IP: 71.5% ± 17.1%), total lung capacity (TLC) (IIP: 73.4% ± 13.6%, PM/DM-IP: 71.6% ± 13.0%), and diffusing capacity DLco (IIP: 57.5% ± 26.7%, PM/DM-IP: 46.4% ± 10.3%). Both groups achieved good responses to initial corticosteroid or immunosuppressant therapy. Patients with anti-ARS antibody-positive IP have common pulmonary manifestations regardless of the presence of PM/DM. Copyright © 2012. Published by Elsevier Ltd.

Efficient reduced graphene oxide grafted porous Fe3O4 composite as a high performance anode material for Li-ion batteries.

PubMed

Bhuvaneswari, Subramani; Pratheeksha, Parakandy Muzhikara; Anandan, Srinivasan; Rangappa, Dinesh; Gopalan, Raghavan; Rao, Tata Narasinga

2014-03-21

Here, we report facile fabrication of Fe3O4-reduced graphene oxide (Fe3O4-RGO) composite by a novel approach, i.e., microwave assisted combustion synthesis of porous Fe3O4 particles followed by decoration of Fe3O4 by RGO. The characterization studies of Fe3O4-RGO composite demonstrate formation of face centered cubic hexagonal crystalline Fe3O4, and homogeneous grafting of Fe3O4 particles by RGO. The nitrogen adsorption-desorption isotherm shows presence of a porous structure with a surface area and a pore volume of 81.67 m(2) g(-1), and 0.106 cm(3) g(-1) respectively. Raman spectroscopic studies of Fe3O4-RGO composite confirm the existence of graphitic carbon. Electrochemical studies reveal that the composite exhibits high reversible Li-ion storage capacity with enhanced cycle life and high coulombic efficiency. The Fe3O4-RGO composite showed a reversible capacity ∼612, 543, and ∼446 mA h g(-1) at current rates of 1 C, 3 C and 5 C, respectively, with a coulombic efficiency of 98% after 50 cycles, which is higher than graphite, and Fe3O4-carbon composite. The cyclic voltammetry experiment reveals the irreversible and reversible Li-ion storage in Fe3O4-RGO composite during the starting and subsequent cycles. The results emphasize the importance of our strategy which exhibited promising electrochemical performance in terms of high capacity retention and good cycling stability. The synergistic properties, (i) improved ionic diffusion by porous Fe3O4 particles with a high surface area and pore volume, and (ii) increased electronic conductivity by RGO grafting attributed to the excellent electrochemical performance of Fe3O4, which make this material attractive to use as anode materials for lithium ion storage.

Diffusion in Brain Extracellular Space

PubMed Central

Syková, Eva; Nicholson, Charles

2009-01-01

Diffusion in the extracellular space (ECS) of the brain is constrained by the volume fraction and the tortuosity and a modified diffusion equation represents the transport behavior of many molecules in the brain. Deviations from the equation reveal loss of molecules across the blood-brain barrier, through cellular uptake, binding or other mechanisms. Early diffusion measurements used radiolabeled sucrose and other tracers. Presently, the real-time iontophoresis (RTI) method is employed for small ions and the integrative optical imaging (IOI) method for fluorescent macromolecules, including dextrans or proteins. Theoretical models and simulations of the ECS have explored the influence of ECS geometry, effects of dead-space microdomains, extracellular matrix and interaction of macromolecules with ECS channels. Extensive experimental studies with the RTI method employing the cation tetramethylammonium (TMA) in normal brain tissue show that the volume fraction of the ECS typically is about 20% and the tortuosity about 1.6 (i.e. free diffusion coefficient of TMA is reduced by 2.6), although there are regional variations. These parameters change during development and aging. Diffusion properties have been characterized in several interventions, including brain stimulation, osmotic challenge and knockout of extracellular matrix components. Measurements have also been made during ischemia, in models of Alzheimer's and Parkinson's diseases and in human gliomas. Overall, these studies improve our conception of ECS structure and the roles of glia and extracellular matrix in modulating the ECS microenvironment. Knowledge of ECS diffusion properties are valuable in contexts ranging from understanding extrasynaptic volume transmission to the development of paradigms for drug delivery to the brain. PMID:18923183

Effects of molecular size and structure on self-diffusion coefficient and viscosity for saturated hydrocarbons having six carbon atoms.

PubMed

Iwahashi, Makio; Kasahara, Yasutoshi

2007-01-01

Self-diffusion coefficients and viscosities for the saturated hydrocarbons having six carbon atoms such as hexane, 2-methylpentane (2MP), 3-methylpentane (3MP), 2,2-dimethylbutane (22DMB), 2,3-dimethylbutane (23DMB), methylcyclopentane (McP) and cyclohexane (cH) were measured at various constant temperatures; obtained results were discussed in connection with their molar volumes, molecular structures and thermodynamic properties. The values of self-diffusion coefficients as the microscopic property were inversely proportional to those of viscosities as the macroscopic property. The order of their viscosities was almost same to those of their melting temperatures and enthalpies of fusion, which reflect the attractive interactions among their molecules. On the other hand, the order of the self-diffusion coefficients inversely related to the order of the melting temperatures and the enthalpies of the fusion. Namely, the compound having the larger attractive interaction mostly shows the less mobility in its liquid state, e.g., cyclohexane (cH), having the largest attractive interaction and the smallest molar volume exhibits an extremely large viscosity and small self-diffusion coefficient comparing with other hydrocarbons. However, a significant exception was 22DMB, being most close to a sphere: In spite of the smallest attractive interaction and the largest molar volume of 22DMB in the all samples, it has the thirdly larger viscosity and the thirdly smaller self-diffusion coefficient. Consequently, the dynamical properties such as self-diffusion and viscosity for the saturated hydrocarbons are determined not only by their attractive interactions but also by their molecular structures.

Exercise Capacity and Selected Physiological Factors by Ancestry and Residential Altitude: Cross-Sectional Studies of 9–10-Year-Old Children in Tibet

PubMed Central

Berntsen, Sveinung; Andersen, Lars Bo; Stigum, Hein; Ouzhuluobu; Nafstad, Per; Wu, Tianyi; Bjertness, Espen

2014-01-01

Abstract Bianba, Sveinung Bernsten, Lars Bo Andersen, Hein Stegum, Ouzhuluobu, Per Nafstad, Tianyi Wu, and Espen Bjertness. Exercise capacity and selected physiological factors by ancestry and residential altitude—Cross-sectional studies of 9–10-year-old children in Tibet. High Alt Med Biol. 15:162–169, 2014.—Aim: Several physiological compensatory mechanisms have enabled Tibetans to live and work at high altitude, including increased ventilation and pulmonary diffusion capacity, both of which serve to increase oxygen transport in the blood. The aim of the present study was to compare exercise capacity (maximal power output) and selected physiological factors (arterial oxygen saturation and heart rate at rest and during maximal exercise, resting hemoglobin concentration, and forced vital capacity) in groups of native Tibetan children living at different residential altitudes (3700 vs. 4300 m above sea level) and across ancestry (native Tibetan vs. Han Chinese children living at the same altitude of 3700 m). Methods: A total of 430 9–10-year-old native Tibetan children from Tingri (4300 m) and 406 native Tibetan- and 406 Han Chinese immigrants (77% lowland-born and 33% highland-born) from Lhasa (3700 m) participated in two cross-sectional studies. The maximal power output (Wmax) was assessed using an ergometer cycle. Results: Lhasa Tibetan children had a 20% higher maximal power output (watts/kg) than Tingri Tibetan and 4% higher than Lhasa Han Chinese. Maximal heart rate, arterial oxygen saturation at rest, lung volume, and arterial oxygen saturation were significantly associated with exercise capacity at a given altitude, but could not fully account for the differences in exercise capacity observed between ancestry groups or altitudes. Conclusions: The superior exercise capacity in native Tibetans vs. Han Chinese may reflect a better adaptation to life at high altitude. Tibetans at the lower residential altitude of 3700 m demonstrated a better exercise capacity than residents at a higher altitude of 4300 m when measured at their respective residential altitudes. Such altitude- or ancestry-related difference could not be fully attributed to the physiological factors measured. PMID:24836751

Pretreatment Prediction of Brain Tumors' Response to Radiation Therapy Using High b-Value Diffusion-Weighted MRI1

PubMed Central

Mardor, Yael; Roth, Yiftach; Ocherashvilli, Aharon; Spiegelmann, Roberto; Tichler, Thomas; Daniels, Dianne; Maier, Stephan E; Nissim, Ouzi; Ram, Zvi; Baram, Jacob; Orenstein, Arie; Pfeffer, Raphael

2004-01-01

Abstract Diffusion-weighted magnetic resonance imaging (DWMRI) is sensitive to tissues' biophysical characteristics, including apparent diffusion coefficients (ADCs) and volume fractions of water in different populations. In this work, we evaluate the clinical efficacy of DWMRI and high diffusion-weighted magnetic resonance imaging (HDWMRI), acquired up to b = 4000 sec/mm2 to amplify sensitivity to water diffusion properties, in pretreatment prediction of brain tumors' response to radiotherapy. Twelve patients with 20 brain lesions were studied. Six ring-enhancing lesions were excluded due to their distinct diffusion characteristics. Conventional and DWMRI were acquired on a 0.5-T MRI. Response to therapy was determined from relative changes in tumor volumes calculated from contrast-enhanced T1-weighted MRI, acquired before and a mean of 46 days after beginning therapy. ADCs and a diffusion index, RD, reflecting tissue viability based on water diffusion were calculated from DWMRIs. Pretreatment values of ADC and RD were found to correlate significantly with later tumor response/nonresponse (r = 0.76, P < .002 and r = 0.77, P < .001). This correlation implies that tumors with low pretreatment diffusion values, indicating high viability, will respond better to radiotherapy than tumors with high diffusion values, indicating necrosis. These results demonstrate the feasibility of using DWMRI for pretreatment prediction of response to therapy in patients with brain tumors undergoing radiotherapy. PMID:15140402

Pretreatment prediction of brain tumors' response to radiation therapy using high b-value diffusion-weighted MRI.

PubMed

Mardor, Yael; Roth, Yiftach; Ochershvilli, Aharon; Spiegelmann, Roberto; Tichler, Thomas; Daniels, Dianne; Maier, Stephan E; Nissim, Ouzi; Ram, Zvi; Baram, Jacob; Orenstein, Arie; Pfeffer, Raphael

2004-01-01

Diffusion-weighted magnetic resonance imaging (DWMRI) is sensitive to tissues' biophysical characteristics, including apparent diffusion coefficients (ADCs) and volume fractions of water in different populations. In this work, we evaluate the clinical efficacy of DWMRI and high diffusion-weighted magnetic resonance imaging (HDWMRI), acquired up to b = 4000 sec/mm(2) to amplify sensitivity to water diffusion properties, in pretreatment prediction of brain tumors' response to radiotherapy. Twelve patients with 20 brain lesions were studied. Six ring-enhancing lesions were excluded due to their distinct diffusion characteristics. Conventional and DWMRI were acquired on a 0.5-T MRI. Response to therapy was determined from relative changes in tumor volumes calculated from contrast-enhanced T1-weighted MRI, acquired before and a mean of 46 days after beginning therapy. ADCs and a diffusion index, R(D), reflecting tissue viability based on water diffusion were calculated from DWMRIs. Pretreatment values of ADC and R(D) were found to correlate significantly with later tumor response/nonresponse (r = 0.76, P <.002 and r = 0.77, P <.001). This correlation implies that tumors with low pretreatment diffusion values, indicating high viability, will respond better to radiotherapy than tumors with high diffusion values, indicating necrosis. These results demonstrate the feasibility of using DWMRI for pretreatment prediction of response to therapy in patients with brain tumors undergoing radiotherapy.

Enhanced Adsorption of Trivalent Arsenic from Water by Functionalized Diatom Silica Shells

PubMed Central

Zhang, Zhijian; Xu, Liping; Zhang, Chunlong

2015-01-01

The potential of porous diatom silica shells as a naturally abundant low-cost sorbent for the removal of arsenic in aqueous solutions was investigated in a batch study. The objective of this work was to chemically modify the silica shells of a diatom Melosira sp. with bifunctional (thiol and amino) groups to effectively remove arsenic in its toxic As(III) form (arsenite) predominant in the aquatic environment. Sorption experiments with this novel sorbent were conducted under varying conditions of pH, time, dosage, and As(III) concentration. A maximum adsorption capacity of 10.99 mg g-1 was achieved within 26 h for a solution containing 12 mg L-1 As(III) at pH 4 and sorbent dosage of 2 g L-1. The functionalized diatom silica shells had a surface morphological change which was accompanied by increased pore size at the expense of reduced specific surface area and total pore volume. As(III) adsorption was best fitted with the Langmuir-Freundlich model, and the adsorption kinetic data using pore surface diffusion model showed that both the external (film) and internal (intraparticle) diffusion can be rate-determining for As(III) adsorption. Fourier transform infrared spectroscopy (FTIR) indicated that the thiol and amino groups potentially responsible for As(III) adsorption were grafted on the surface of diatom silica shells. X-ray photoelectron spectroscopy (XPS) further verified that this unique sorbent proceeded via a chemisorption mechanism through the exchange between oxygen-containing groups of neutral As(III) and thiol groups, and through the surface complexation between As(III) and protonated nitrogen and hydroxyl groups. Results indicate that this functionalized bioadsorbent with a high As(III) adsorption capacity holds promise for the treatment of As(III) containing wastewater. PMID:25837498

Lung volumes and maximal respiratory pressures in collegiate swimmers and runners.

PubMed

Cordain, L; Tucker, A; Moon, D; Stager, J M

1990-03-01

To determine whether respiratory muscle strength is related to pulmonary volume differences in athletes and nonathletes, 11 intercollegiate female swimmers, 11 female cross-country runners, and two nonathletic control groups, matched to the athletes in height and age, were evaluated for pulmonary parameters including maximal inspiratory pressure (PImax) and maximal expiratory pressure (PEmax). Swimmers exhibited larger (p less than .05) vital capacities (VC), residual lung volumes (RV), inspiratory capacities (IC), and functional residual capacities (FRC) than both the runners or the controls but no difference (p greater than .05) in either PImax or inspiratory flow (FIV 25%-75%). Timed expiratory volumes (FEV 0.5 and FEV 1.0) were significantly (p less than .05) lower in the swimmers than in the controls. These data suggest that an adaptational growth may be responsible, in part, for the augmented static lung volumes demonstrated in swimmers.

Lung diffusion capacity in children with respiratory symptoms and untreated GERD.

PubMed

Mirić, Mirjana; Turkalj, Mirjana; Nogalo, Boro; Erceg, Damir; Perica, Marija; Plavec, Davor

2014-05-12

Gastroesophageal reflux disease (GERD) is associated with many respiratory disorders, among which, chronic cough, laryngitis, and asthma are among the most common. We investigated lung function, including gas diffusion capacity, in children with poor asthma control or chronic laryngitis with untreated GERD. A total of 71 children, aged 6-17 years, with chronic respiratory and other symptoms suggestive for GERD, were enrolled and divided into 2 groups: chronic laryngitis and asthma. Participants underwent 24-hour pH monitoring and lung function assessment, measurement of single-breath diffusing capacity of the lung for carbon monoxide (DLCO), and fraction of exhaled nitric oxide (FENO) measurement. 24-hour pH monitoring was positive for GERD in 92.1% of preselected children with asthma and 90.1% of children with chronic recurrent laryngitis. All flows (PEF, MEF75, MEF50, and MEF25) were significantly lower in the asthma group, while FENO and DLCO were significantly lower in the laryngitis group. A significant inverse relationship was found between DLCO and all reflux indexes in the laryngitis group. Each unit change of Johnson-DeMeester score and Boix-Ochoa score increased the odds for significantly lower DLCO in laryngitis patients by 3.9% and 5.5%, respectively. In children with uncontrolled asthma and chronic laryngitis, the regurgitation of gastric contents due to GERD contributes to poor asthma control and aggravation of chronic laryngitis. Despite having normal lung function, the gas diffusion capacity should be controlled in patients with GERD and chronic laryngitis, and it might be the very first abnormality in distal airways.

Role of Anemia in Home Oxygen Therapy in Chronic Obstructive Pulmonary Disease Patients.

PubMed

Copur, Ahmet Sinan; Fulambarker, Ashok; Molnar, Janos; Nadeem, Rashid; McCormack, Charles; Ganesh, Aarthi; Kheir, Fayez; Hamon, Sara

2015-01-01

Anemia is a known comorbidity found in chronic obstructive pulmonary disease (COPD) patients. Hypoxemia is common and basically due to ventilation/perfusion (V/Q) mismatch in COPD. Anemia, by decreasing arterial oxygen content, may be a contributing factor for decreased delivery of oxygen to tissues. The objective of this study is to determine if anemia is a factor in qualifying COPD patients for home oxygen therapy. The study was designed as a retrospective, cross-sectional, observational chart review. Patients who were referred for home oxygen therapy evaluation were selected from the computerized patient record system. Demographic data, oxygen saturation at rest and during exercise, pulmonary function test results, hemoglobin level, medications, reason for anemia, comorbid diseases, and smoking status were recorded. The χ tests, independent sample t tests, and logistic regression were used for statistical analysis. Only 356 of total 478 patient referrals had a diagnosis of COPD over a 2-year period. Although 39 of them were excluded, 317 patients were included in the study. The overall rate of anemia was 38% in all COPD patients. Anemia was found significantly more frequent in COPD patients on home oxygen therapy (46%) than those not on home oxygen therapy (18.5%) (P < 0.0001). Mean saturation of peripheral oxygen values were significantly lower in anemic COPD patients both at rest and during exercise (P < 0.0001). Also, in COPD patients, age, Global Initiative for Chronic Obstructive Lung Disease class, smoking status, hemoglobin level, hematocrit, percent of forced expiratory volume in first second, forced expiratory volume in first second/forced vital capacity, residual volume/total lung volume, percent of carbon monoxide diffusion capacity were significantly different between home oxygen therapy and those not on home oxygen therapy (P < 0.05). Multivariate logistic regression showed that anemia remained a strong predictor for long-term oxygen therapy use in COPD patients after adjusting for other significant parameters. Anemic COPD patients are more hypoxic especially during exercise than those who are not anemic. We conclude that anemia is a contributing factor in qualifying COPD patients for home oxygen therapy.

T2* measurements of 3-T MRI with ultrashort TEs: capabilities of pulmonary function assessment and clinical stage classification in smokers.

PubMed

Ohno, Yoshiharu; Koyama, Hisanobu; Yoshikawa, Takeshi; Matsumoto, Keiko; Takahashi, Masaya; Van Cauteren, Marc; Sugimura, Kazuro

2011-08-01

The purpose of this study was to determine the usefulness of MRI with ultrashort TEs on a 3-T system and of thin-section MDCT for pulmonary function assessment and clinical stage classification of chronic obstructive pulmonary disease (COPD) in smokers. Forty smokers (24 men and 16 women; mean age ± SD, 68.0 ± 9.3 years) underwent MRI with ultrashort TEs and thin-section MDCT. Pulmonary function testing was also performed to determine the following: the ratio of forced expiratory volume in 1 second to forced vital capacity (percentage predicted) (FEV(1/)FVC%), percentage predicted forced expiratory volume in 1 second (%FEV(1)), and percentage predicted diffusing capacity of lung for carbon monoxide corrected for alveolar volume (%DLCO/V(A)). All subjects were classified into one of four groups as follows: smokers without COPD, with mild COPD, with moderate COPD, and with severe or very severe COPD. T2(*) maps were expressed using proprietary software. Regional T2(*) values were determined by region of interest measurements and were averaged to determine a mean T2(*) value for each subject. CT-based functional lung volume and the ratio of the wall area to the total airway area were also determined. All indexes were statistically correlated with pulmonary function parameters. Then, all indexes were compared among all groups by means of Tukey's honest significance test. All indexes had significant correlation with FEV(1)/FVC%, %FEV(1), and % DLCO/V(A) (p < 0.05). All indexes except WA% of smokers without COPD and smokers with mild COPD differed significantly from those of smokers with moderate COPD and smokers with severe or very severe COPD (p < 0.05). Moreover, the mean T2(*) value of the moderate COPD group was significantly different from that of the severe or very severe COPD group (p < 0.05). MRI with ultrashort TEs is potentially as useful as quantitatively assessed MDCT for pulmonary function loss assessment and clinical stage classification of COPD in smokers.

A diffusion tensor imaging tractography algorithm based on Navier-Stokes fluid mechanics.

PubMed

Hageman, Nathan S; Toga, Arthur W; Narr, Katherine L; Shattuck, David W

2009-03-01

We introduce a fluid mechanics based tractography method for estimating the most likely connection paths between points in diffusion tensor imaging (DTI) volumes. We customize the Navier-Stokes equations to include information from the diffusion tensor and simulate an artificial fluid flow through the DTI image volume. We then estimate the most likely connection paths between points in the DTI volume using a metric derived from the fluid velocity vector field. We validate our algorithm using digital DTI phantoms based on a helical shape. Our method segmented the structure of the phantom with less distortion than was produced using implementations of heat-based partial differential equation (PDE) and streamline based methods. In addition, our method was able to successfully segment divergent and crossing fiber geometries, closely following the ideal path through a digital helical phantom in the presence of multiple crossing tracts. To assess the performance of our algorithm on anatomical data, we applied our method to DTI volumes from normal human subjects. Our method produced paths that were consistent with both known anatomy and directionally encoded color images of the DTI dataset.

A Diffusion Tensor Imaging Tractography Algorithm Based on Navier-Stokes Fluid Mechanics

PubMed Central

Hageman, Nathan S.; Toga, Arthur W.; Narr, Katherine; Shattuck, David W.

2009-01-01

We introduce a fluid mechanics based tractography method for estimating the most likely connection paths between points in diffusion tensor imaging (DTI) volumes. We customize the Navier-Stokes equations to include information from the diffusion tensor and simulate an artificial fluid flow through the DTI image volume. We then estimate the most likely connection paths between points in the DTI volume using a metric derived from the fluid velocity vector field. We validate our algorithm using digital DTI phantoms based on a helical shape. Our method segmented the structure of the phantom with less distortion than was produced using implementations of heat-based partial differential equation (PDE) and streamline based methods. In addition, our method was able to successfully segment divergent and crossing fiber geometries, closely following the ideal path through a digital helical phantom in the presence of multiple crossing tracts. To assess the performance of our algorithm on anatomical data, we applied our method to DTI volumes from normal human subjects. Our method produced paths that were consistent with both known anatomy and directionally encoded color (DEC) images of the DTI dataset. PMID:19244007

Molecular dynamics simulation of diffusion of gases in a carbon-nanotube-polymer composite

NASA Astrophysics Data System (ADS)

Lim, Seong Y.; Sahimi, Muhammad; Tsotsis, Theodore T.; Kim, Nayong

2007-07-01

Extensive molecular dynamics (MD) simulations were carried out to compute the solubilities and self-diffusivities of CO2 and CH4 in amorphous polyetherimide (PEI) and mixed-matrix PEI generated by inserting single-walled carbon nanotubes into the polymer. Atomistic models of PEI and its composites were generated using energy minimizations, MD simulations, and the polymer-consistent force field. Two types of polymer composite were generated by inserting (7,0) and (12,0) zigzag carbon nanotubes into the PEI structure. The morphologies of PEI and its composites were characterized by their densities, radial distribution functions, and the accessible free volumes, which were computed with probe molecules of different sizes. The distributions of the cavity volumes were computed using the Voronoi tessellation method. The computed self-diffusivities of the gases in the polymer composites are much larger than those in pure PEI. We find, however, that the increase is not due to diffusion of the gases through the nanotubes which have smooth energy surfaces and, therefore, provide fast transport paths. Instead, the MD simulations indicate a squeezing effect of the nanotubes on the polymer matrix that changes the composite polymers’ free-volume distributions and makes them more sharply peaked. The presence of nanotubes also creates several cavities with large volumes that give rise to larger diffusivities in the polymer composites. This effect is due to the repulsive interactions between the polymer and the nanotubes. The solubilities of the gases in the polymer composites are also larger than those in pure PEI, hence indicating larger gas permeabilities for mixed-matrix PEI than PEI itself.

Size quantization in high-temperature superconducting cuprates and a link to Einstein's diffusion law

NASA Astrophysics Data System (ADS)

Roeser, H. P.; Bohr, A.; Haslam, D. T.; López, J. S.; Stepper, M.; Nikoghosyan, A. S.

2012-07-01

Optimum doping of high-temperature superconductors (HTSC) defines a superconducting unit volume for each HTSC. For a single-mode HTSC, e.g., a cuprate with one CuO2 plane, the volume is given by Vsc=cx2, where c is the unit cell height and x the doping distance. The experimental resistivity at Tc is connected to the structure by ρ(exp)≈c×h/(2e2). Combining this result with the classical definition of resistivity leads to an equation similar to Einstein's diffusion law x2/(2τ)=h/(2Meff)=D, where τ is the relaxation time, Meff=2me and D the diffusion constant. It has also been shown that the mean free path d=x. The Einstein-Smoluchowski diffusion relation D=μkBTc provides a connection to Tc.

Integral approximations to classical diffusion and smoothed particle hydrodynamics

DOE PAGES

Du, Qiang; Lehoucq, R. B.; Tartakovsky, A. M.

2014-12-31

The contribution of the paper is the approximation of a classical diffusion operator by an integral equation with a volume constraint. A particular focus is on classical diffusion problems associated with Neumann boundary conditions. By exploiting this approximation, we can also approximate other quantities such as the flux out of a domain. Our analysis of the model equation on the continuum level is closely related to the recent work on nonlocal diffusion and peridynamic mechanics. In particular, we elucidate the role of a volumetric constraint as an approximation to a classical Neumann boundary condition in the presence of physical boundary.more » The volume-constrained integral equation then provides the basis for accurate and robust discretization methods. As a result, an immediate application is to the understanding and improvement of the Smoothed Particle Hydrodynamics (SPH) method.« less

Quantitative assessment of the hepatic metabolic volume product in patients with diffuse hepatic steatosis and normal controls through use of FDG-PET and MR imaging: a novel concept.

PubMed

Bural, Gonca G; Torigian, Drew A; Burke, Anne; Houseni, Mohamed; Alkhawaldeh, Khaled; Cucchiara, Andrew; Basu, Sandip; Alavi, Abass

2010-06-01

The aim of this study was to compare hepatic standardized uptake values (SUVs) and hepatic metabolic volumetric products (HMVP) between patients of diffuse hepatic steatosis and control subjects with normal livers. Twenty-seven subjects were included in the study (13 men and 14 women; age range, 34-72 years). All had 18F-2-fluoro-2-D-deoxyglucose-positron emission tomography (FDG-PET) and magnetic resonance imaging (MRI) scans with an interscan interval of 0-5 months. Twelve of 27 subjects had diffuse hepatic steatosis on MRI. The remaining 15 were selected as age-matched controls based on normal liver parenchyma on MRI. Mean and maximum hepatic SUVs were calculated for both patient groups on FDG-PET images. Hepatic volumes were measured from MRI. HMVP in each subject was subsequently calculated by multiplication of hepatic volume by mean hepatic SUV. HMVPs as well as mean and maximum hepatic SUVs were compared between the two study groups. HMVPs, mean hepatic SUVs, and maximum hepatic SUVs were greater (statistically significant, p < 0.05) in subjects with diffuse hepatic steatosis compared to those in the control group. The increase in HMVP is the result of increased hepatic metabolic activity likely related to the diffuse hepatic steatosis. The active inflammatory process related to the diffuse hepatic steatosis is the probable explanation for the increase in hepatic metabolic activity on FDG-PET study.

A diffusion model-free framework with echo time dependence for free-water elimination and brain tissue microstructure characterization.

PubMed

Molina-Romero, Miguel; Gómez, Pedro A; Sperl, Jonathan I; Czisch, Michael; Sämann, Philipp G; Jones, Derek K; Menzel, Marion I; Menze, Bjoern H

2018-03-23

The compartmental nature of brain tissue microstructure is typically studied by diffusion MRI, MR relaxometry or their correlation. Diffusion MRI relies on signal representations or biophysical models, while MR relaxometry and correlation studies are based on regularized inverse Laplace transforms (ILTs). Here we introduce a general framework for characterizing microstructure that does not depend on diffusion modeling and replaces ill-posed ILTs with blind source separation (BSS). This framework yields proton density, relaxation times, volume fractions, and signal disentanglement, allowing for separation of the free-water component. Diffusion experiments repeated for several different echo times, contain entangled diffusion and relaxation compartmental information. These can be disentangled by BSS using a physically constrained nonnegative matrix factorization. Computer simulations, phantom studies, together with repeatability and reproducibility experiments demonstrated that BSS is capable of estimating proton density, compartmental volume fractions and transversal relaxations. In vivo results proved its potential to correct for free-water contamination and to estimate tissue parameters. Formulation of the diffusion-relaxation dependence as a BSS problem introduces a new framework for studying microstructure compartmentalization, and a novel tool for free-water elimination. © 2018 International Society for Magnetic Resonance in Medicine.

No effect of artificial gravity on lung function with exercise training during head-down bed rest

NASA Astrophysics Data System (ADS)

Su, Longxiang; Guo, Yinghua; Wang, Yajuan; Wang, Delong; Liu, Changting

2016-04-01

The aim of this study is to explore the effectiveness of microgravity simulated by head-down bed rest (HDBR) and artificial gravity (AG) with exercise on lung function. Twenty-four volunteers were randomly divided into control and exercise countermeasure (CM) groups for 96 h of 6° HDBR. Comparisons of pulse rate, pulse oxygen saturation (SpO2) and lung function were made between these two groups at 0, 24, 48, 72, 96 h. Compared with the sitting position, inspiratory capacity and respiratory reserve volume were significantly higher than before HDBR (0° position) (P < 0.05). Vital capacity, expiratory reserve volume, forced vital capacity, forced expiratory volume in 1 s, forced inspiratory vital capacity, forced inspiratory volume in 1 s, forced expiratory flow at 25, 50, and 75%, maximal mid-expiratory flow and peak expiratory flow were all significantly lower than those before HDBR (P < 0.05). Neither control nor CM groups showed significant differences in pulse rate, SpO2, pulmonary volume and pulmonary ventilation function over the HDBR observation time. Postural changes can lead to variation in lung volume and ventilation function, but a HDBR model induced no changes in pulmonary function and therefore should not be used to study AG countermeasures.

Drug Loading Capacity of Environmentally Sensitive Polymeric Microgels

NASA Astrophysics Data System (ADS)

McDonough, Ryan; Streletzky, Kiril; Bayachou, Mekki; Peiris, Pubudu

2009-10-01

Microgel nanoparticles consisting of cross-linked polymer hydroxypropyl cellulose chains have a temperature dependent volume phase transition, prompting the use of microgels for controlled drug transport. Drug particles aggregate in the slightly hydrophobic interior of microgels. Microgels are stored in equilibrium until the critical temperature (Tv) is reached and the volume phase transition limits available space, thus expelling the drugs. Our study was designed to test this property of microgels using amperometric electrochemical methods. A critical assumption was that small molecules inside microgels would not interact via diffusion with the electrode surface and thus total current would be decreased across the electrodes in a microgel sample. A room temperature (Troom) flow amperometric measurement comparing microgel/tylenol solution with control tylenol samples yielded about 20% tylenol concentration reduction of the microgel sample. Results from the steady state electrochemical experiment confirm the presence of about 20% tylenol concentration drop of the microgel sample compared to control sample at Troom. Using the steady-state experiment with a cyclic temperature ramp from Troom to beyond Tv showed that the tylenol concentration change between the temperature extremes was greater for the microgel solution than for the control solution.

Storage capacity of the Fena Valley Reservoir, Guam, Mariana Islands, 2014

USGS Publications Warehouse

Marineau, Mathieu D.; Wright, Scott A.

2015-01-01

Analyses of the bathymetric data indicate that the reservoir currently has 6,915 acre-feet of storage capacity. The engineering drawings of record show that the total reservoir capacity in 1951 was estimated to be 8,365 acre-feet. Thus, between 1951 and 2014, the total storage capacity decreased by 1,450 acre-feet (a loss of 17 percent of the original total storage capacity). The remaining live-storage capacity, or the volume of storage above the lowest-level reservoir outlet elevation, was calculated to be 5,511 acre-feet in 2014, indicating a decrease of 372 acre-feet (or 6 percent) of the original 5,883 acre-feet of live-storage capacity. The remaining dead-storage capacity, or volume of storage below the lowest-level outlet, was 1,404 acre-feet in 2014, indicating a decrease of 1,078 acre-feet (or 43 percent) of the original 2,482 acre-feet of dead-storage capacity.

Predicting the influence of long-range molecular interactions on macroscopic-scale diffusion by homogenization of the Smoluchowski equation

NASA Astrophysics Data System (ADS)

Kekenes-Huskey, P. M.; Gillette, A. K.; McCammon, J. A.

2014-05-01

The macroscopic diffusion constant for a charged diffuser is in part dependent on (1) the volume excluded by solute "obstacles" and (2) long-range interactions between those obstacles and the diffuser. Increasing excluded volume reduces transport of the diffuser, while long-range interactions can either increase or decrease diffusivity, depending on the nature of the potential. We previously demonstrated [P. M. Kekenes-Huskey et al., Biophys. J. 105, 2130 (2013)] using homogenization theory that the configuration of molecular-scale obstacles can both hinder diffusion and induce diffusional anisotropy for small ions. As the density of molecular obstacles increases, van der Waals (vdW) and electrostatic interactions between obstacle and a diffuser become significant and can strongly influence the latter's diffusivity, which was neglected in our original model. Here, we extend this methodology to include a fixed (time-independent) potential of mean force, through homogenization of the Smoluchowski equation. We consider the diffusion of ions in crowded, hydrophilic environments at physiological ionic strengths and find that electrostatic and vdW interactions can enhance or depress effective diffusion rates for attractive or repulsive forces, respectively. Additionally, we show that the observed diffusion rate may be reduced independent of non-specific electrostatic and vdW interactions by treating obstacles that exhibit specific binding interactions as "buffers" that absorb free diffusers. Finally, we demonstrate that effective diffusion rates are sensitive to distribution of surface charge on a globular protein, Troponin C, suggesting that the use of molecular structures with atomistic-scale resolution can account for electrostatic influences on substrate transport. This approach offers new insight into the influence of molecular-scale, long-range interactions on transport of charged species, particularly for diffusion-influenced signaling events occurring in crowded cellular environments.

Non-universal tracer diffusion in crowded media of non-inert obstacles.

PubMed

Ghosh, Surya K; Cherstvy, Andrey G; Metzler, Ralf

2015-01-21

We study the diffusion of a tracer particle, which moves in continuum space between a lattice of excluded volume, immobile non-inert obstacles. In particular, we analyse how the strength of the tracer-obstacle interactions and the volume occupancy of the crowders alter the diffusive motion of the tracer. From the details of partitioning of the tracer diffusion modes between trapping states when bound to obstacles and bulk diffusion, we examine the degree of localisation of the tracer in the lattice of crowders. We study the properties of the tracer diffusion in terms of the ensemble and time averaged mean squared displacements, the trapping time distributions, the amplitude variation of the time averaged mean squared displacements, and the non-Gaussianity parameter of the diffusing tracer. We conclude that tracer-obstacle adsorption and binding triggers a transient anomalous diffusion. From a very narrow spread of recorded individual time averaged trajectories we exclude continuous type random walk processes as the underlying physical model of the tracer diffusion in our system. For moderate tracer-crowder attraction the motion is found to be fully ergodic, while at stronger attraction strength a transient disparity between ensemble and time averaged mean squared displacements occurs. We also put our results into perspective with findings from experimental single-particle tracking and simulations of the diffusion of tagged tracers in dense crowded suspensions. Our results have implications for the diffusion, transport, and spreading of chemical components in highly crowded environments inside living cells and other structured liquids.

Mechanism of Facilitated Diffusion during a DNA Search in Crowded Environments.

PubMed

Krepel, Dana; Gomez, David; Klumpp, Stefan; Levy, Yaakov

2016-11-03

The key feature explaining the rapid recognition of a DNA target site by its protein lies in the combination of one- and three-dimensional (1D and 3D) diffusion, which allows efficient scanning of the many alternative sites. This facilitated diffusion mechanism is expected to be affected by cellular conditions, particularly crowding, given that up to 40% of the total cellular volume may by occupied by macromolecules. Using coarse-grained molecular dynamics and Monte Carlo simulations, we show that the crowding particles can enhance facilitated diffusion and accelerate search kinetics. This effect originates from a trade-off between 3D and 1D diffusion. The 3D diffusion coefficient is lower under crowded conditions, but it has little influence because the excluded volume effect of molecular crowding restricts its use. Largely prevented from using 3D diffusion, the searching protein dramatically increases its use of the hopping search mode, which results in a higher linear diffusion coefficient. The coefficient of linear diffusion also increases under crowded conditions as a result of increased collisions between the crowding particles and the searching protein. Overall, less 3D diffusion coupled with an increase in the use of the hopping and speed of 1D diffusion results in faster search kinetics under crowded conditions. Our study shows that the search kinetics and mechanism are modulated not only by the crowding occupancy but also by the properties of the crowding particles and the salt concentration.

A multicomponent tracer field experiment to measure the flow volume, surface area, and rectilinear spacing of fractures away from the wellbore

NASA Astrophysics Data System (ADS)

Cathles, L. M.; Sanford, W. E.; Hawkins, A.; Li, Y. V.

2017-12-01

The nature of flow in fractured porous media is important to almost all subsurface processes including oil and gas recovery, contaminant transport and remediation, CO2 sequestration, and geothermal heat extraction. One would like to know, under flowing conditions, the flow volume, surface area, effective aperture, and rectilinear spacing of fractures in a representative volume of rock away from the well bore, but no methods currently allow acquisition of this data. It could, however, be collected by deploying inert tracers with a wide range of aqueous diffusion constants (e.g., rapidly diffusing heat to non-diffusing nanoparticle) in the following fashion: The flow volume is defined by the heated volume measured by resistivity surveys. The fracture volume within this flow volume is indicate by the nanoparticle transit time. The average fracture spacing is indicated by the evolving thermal profile in the monitor and the production wells (measured by fiber optic cable), and by the retention of absorbing tracers. The average fracture aperture is determined by permeability measurements and the average fracture separation. We have proposed a field test to redundantly measure these fracture parameters in the fractured Dakota Sandstone where it approaches the surface in Ft Collins, Colorado. Five 30 m deep wells (an injection, production, and 3 monitor wells) cased to 20 m are proposed. The experiments will involve at least 9 different tracers. The planned field test and its potential significance will be described.

Diffusion of cis-5,8,11,14,17-eicosapentaenoic acid (1); carbon dioxide (2)

NASA Astrophysics Data System (ADS)

Winkelmann, J.

This document is part of Subvolume A `Gases in Gases, Liquids and their Mixtures' of Volume 15 `Diffusion in Gases, Liquids and Electrolytes' of Landolt-Börnstein Group IV `Physical Chemistry'. It is part of the chapter of the chapter `Diffusion in Pure Gases' and contains data on diffusion of (1) cis-5,8,11,14,17-eicosapentaenoic acid; (2) carbon dioxide

Finite Volume Scheme for Double Convection-Diffusion Exchange of Solutes in Bicarbonate High-Flux Hollow-Fiber Dialyzer Therapy

PubMed Central

Annan, Kodwo

2012-01-01

The efficiency of a high-flux dialyzer in terms of buffering and toxic solute removal largely depends on the ability to use convection-diffusion mechanism inside the membrane. A two-dimensional transient convection-diffusion model coupled with acid-base correction term was developed. A finite volume technique was used to discretize the model and to numerically simulate it using MATLAB software tool. We observed that small solute concentration gradients peaked and were large enough to activate solute diffusion process in the membrane. While CO2 concentration gradients diminished from their maxima and shifted toward the end of the membrane, HCO3 − concentration gradients peaked at the same position. Also, CO2 concentration decreased rapidly within the first 47 minutes while optimal HCO3 − concentration was achieved within 30 minutes of the therapy. Abnormally high diffusion fluxes were observed near the blood-membrane interface that increased diffusion driving force and enhanced the overall diffusive process. While convective flux dominated total flux during the dialysis session, there was a continuous interference between convection and diffusion fluxes that call for the need to seek minimal interference between these two mechanisms. This is critical for the effective design and operation of high-flux dialyzers. PMID:23197994

Diffusion, sorption, and retardation processes of anions in bentonite and organo-bentonites for multibarrier systems

NASA Astrophysics Data System (ADS)

Schampera, Birgit; Dultz, Stefan

2013-04-01

The low permeability, high cation exchange capacity (CEC) and plasticity of bentonites favor their use in multibarrier systems of waste deposits [1]. Bentonites have a high CEC but their ability to sorb anions is very low. There is, however, need for retardation of anions and organic pollutants in many applications. Bentonites, modified with certain organic cations, have the capacity to sorb anions and non-polar organic compounds in addition to cations. Investigations on organically modified clays address a wide variety of applications including immobilization of pollutants in contaminated soils, waste water treatment and in situ placement for the protection of ground water [2]. Many experiments on anion and cation sorption of organo-clays were conducted in the batch mode which does not reflect solid-liquid ratios and material densities in barrier systems. Diffusion experiments on compacted clays allow the evaluation of transport processes and sorption of pollutants at conditions relevant for repositories. For organo-clays only few diffusion studies are published e.g. [3] measured the diffusion of tritium and [4] the diffusion of H2O in bentonite and organo-bentonites. The organic cation hexadecylpyridinium (HDPy) was added to Wyoming bentonite (MX-80) in amounts corresponding to 2-400 % of the CEC. The uptake of organic cations was determined by the C-content, XRD and IR-spectroscopy. Wettability was analyzed by the contact angle. Physical, chemical and mineralogical properties of clays were characterized. Diffusion experiments were carried out in situ in a cell attached to the ATR-unit of a FTIR-spectrometer. For H2O-diffusion the compacted organo-clays are saturated first with D2O, afterwards H2O is supplied to the surface at the top of the clay platelet. Anion-diffusion was conducted with NO3--solution instead of H2O only having characteristic IR band positions at 1350 cm-1. Three different concentrations (0.25M, 0.5M and 1M) were used. Additional batch experiments with NO3- will support the understanding of sorption behavior of the anions. All hydrophilic samples have a higher retardation capacity, indicated by diffusion coefficients of 2.44 x 10-11 m/s2 for original bentonite and ˜2.1 x 10-11m/s2 for hydrophilic organo-clays. For hydrophobic organo-clays the H2O diffusion can be higher and is increased at high bulk density (1-1.5 g/m3) up to 2.76 x 10-10m2/s. Experiments with NO3- at bulk density of 1.5 g/m3 reveal that the apparent diffusion coefficients of nitrate are with results up to 5.61 x 1012 m2/s distinctively lower than free diffusion of nitrate in pure water (6.46 x 1010 m2/s at experimental conditions) and nitrate diffusion in natural bentonite (2.63 x 1011 m2/s). The measurements allow the interpretation of the different sorption mechanisms, retardation capacity and diffusion behavior of the analyzed clays at different anion concentrations. Ongoing molecular dynamic simulations will contribute understanding of diffusion processes in organo-clays including the conditions at the interface of the clay minerals and in solution. References: [1] Shackelford, C.D., Moore S.M. (2013) Fickian diffusion of radionuclides for engineered containment barriers: Diffusion coefficients, porosities, and complicating issues. Engineering Geology, 152, 133-147. [2] Rytwo, G., Nir, S., Shuali, U. (2012) Clay and water treatment. Applied Clay Science, 67-68, 117-118. [3] Lorenzetti, R.L., Bartelt-Hunt, S.L., Burns, S.E., Smith, J.A. (2005) Hydraulic conductivities and effective diffusion coefficients of geosynthetic clay liners with organobentonite amendments. Geotextiles and Geomembranes, 23, 385-400. [4] Schampera, B., Dultz, S. (2011) H2O self-diffusion in compacted clays as influenced by surface charge and wettability - obstruction effects of bound H2O layers. Clay and Clay Minerals,59, 42-57.

Body mass scaling of passive oxygen diffusion in endotherms and ectotherms

PubMed Central

Gillooly, James F.; Gomez, Juan Pablo; Mavrodiev, Evgeny V.; Rong, Yue; McLamore, Eric S.

2016-01-01

The area and thickness of respiratory surfaces, and the constraints they impose on passive oxygen diffusion, have been linked to differences in oxygen consumption rates and/or aerobic activity levels in vertebrates. However, it remains unclear how respiratory surfaces and associated diffusion rates vary with body mass across vertebrates, particularly in relation to the body mass scaling of oxygen consumption rates. Here we address these issues by first quantifying the body mass dependence of respiratory surface area and respiratory barrier thickness for a diversity of endotherms (birds and mammals) and ectotherms (fishes, amphibians, and reptiles). Based on these findings, we then use Fick’s law to predict the body mass scaling of oxygen diffusion for each group. Finally, we compare the predicted body mass dependence of oxygen diffusion to that of oxygen consumption in endotherms and ectotherms. We find that the slopes and intercepts of the relationships describing the body mass dependence of passive oxygen diffusion in these two groups are statistically indistinguishable from those describing the body mass dependence of oxygen consumption. Thus, the area and thickness of respiratory surfaces combine to match oxygen diffusion capacity to oxygen consumption rates in both air- and water-breathing vertebrates. In particular, the substantially lower oxygen consumption rates of ectotherms of a given body mass relative to those of endotherms correspond to differences in oxygen diffusion capacity. These results provide insights into the long-standing effort to understand the structural attributes of organisms that underlie the body mass scaling of oxygen consumption. PMID:27118837

Body mass scaling of passive oxygen diffusion in endotherms and ectotherms.

PubMed

Gillooly, James F; Gomez, Juan Pablo; Mavrodiev, Evgeny V; Rong, Yue; McLamore, Eric S

2016-05-10

The area and thickness of respiratory surfaces, and the constraints they impose on passive oxygen diffusion, have been linked to differences in oxygen consumption rates and/or aerobic activity levels in vertebrates. However, it remains unclear how respiratory surfaces and associated diffusion rates vary with body mass across vertebrates, particularly in relation to the body mass scaling of oxygen consumption rates. Here we address these issues by first quantifying the body mass dependence of respiratory surface area and respiratory barrier thickness for a diversity of endotherms (birds and mammals) and ectotherms (fishes, amphibians, and reptiles). Based on these findings, we then use Fick's law to predict the body mass scaling of oxygen diffusion for each group. Finally, we compare the predicted body mass dependence of oxygen diffusion to that of oxygen consumption in endotherms and ectotherms. We find that the slopes and intercepts of the relationships describing the body mass dependence of passive oxygen diffusion in these two groups are statistically indistinguishable from those describing the body mass dependence of oxygen consumption. Thus, the area and thickness of respiratory surfaces combine to match oxygen diffusion capacity to oxygen consumption rates in both air- and water-breathing vertebrates. In particular, the substantially lower oxygen consumption rates of ectotherms of a given body mass relative to those of endotherms correspond to differences in oxygen diffusion capacity. These results provide insights into the long-standing effort to understand the structural attributes of organisms that underlie the body mass scaling of oxygen consumption.

Effects of tiotropium on lung hyperinflation, dyspnoea and exercise tolerance in COPD.

PubMed

O'Donnell, D E; Flüge, T; Gerken, F; Hamilton, A; Webb, K; Aguilaniu, B; Make, B; Magnussen, H

2004-06-01

The aim of this study was to test the hypothesis that use of tiotropium, a new long-acting anticholinergic bronchodilator, would be associated with sustained reduction in lung hyperinflation and, thereby, would improve exertional dyspnoea and exercise performance in patients with chronic obstructive pulmonary disease. A randomised, double-blind, placebo-controlled, parallel-group study was conducted in 187 patients (forced expiratory volume in one second 44 +/- 13% pred): 96 patients received 18 microg tiotropium and 91 patients received placebo once daily for 42 days. Spirometry, plethysmographic lung volumes, cycle exercise endurance and exertional dyspnoea intensity at 75% of each patient's maximal work capacity were compared. On day 42, the use of tiotropium was associated with the following effects at pre-dose and post-dose measurements as compared to placebo: vital capacity and inspiratory capacity (IC) increased, with inverse decreases in residual volume and functional residual capacity. Tiotropium increased post-dose exercise endurance time by 105 +/- 40 s (21%) as compared to placebo on day 42. At a standardised time near end-exercise (isotime), IC, tidal volume and minute ventilation all increased, whilst dyspnoea decreased by 0.9 +/- 0.3 Borg scale units. In conclusion, the use of tiotropium was associated with sustained reductions of lung hyperinflation at rest and during exercise. Resultant increases in inspiratory capacity permitted greater expansion of tidal volume and contributed to improvements in both exertional dyspnoea and exercise endurance.

Sexual dimorphism of volume reduction but not cognitive deficit in fetal alcohol spectrum disorders: A combined diffusion tensor imaging, cortical thickness and brain volume study.

PubMed

Treit, Sarah; Chen, Zhang; Zhou, Dongming; Baugh, Lauren; Rasmussen, Carmen; Andrew, Gail; Pei, Jacqueline; Beaulieu, Christian

2017-01-01

Quantitative magnetic resonance imaging (MRI) has revealed abnormalities in brain volumes, cortical thickness and white matter microstructure in fetal alcohol spectrum disorders (FASD); however, no study has reported all three measures within the same cohort to assess the relative magnitude of deficits, and few studies have examined sex differences. Participants with FASD (n = 70; 30 females; 5-32 years) and healthy controls (n = 74; 35 females; 5-32 years) underwent cognitive testing and MRI to assess cortical thickness, regional brain volumes and fractional anisotropy (FA)/mean diffusivity (MD) of white matter tracts. A significant effect of group, age-by-group, or sex-by-group was found for 9/9 volumes, 7/39 cortical thickness regions, 3/9 white matter tracts, and 9/10 cognitive tests, indicating group differences that in some cases differ by age or sex. Volume reductions for several structures were larger in males than females, despite similar deficits of cognition in both sexes. Correlations between brain structure and cognitive scores were found in females of both groups, but were notably absent in males. Correlations within a given MRI modality (e.g. total brain volume and caudate volume) were prevalent in both the control and FASD groups, and were more numerous than correlations between measurement types (e.g. volumes and diffusion tensor imaging) in either cohort. This multi-modal MRI study finds widespread differences of brain structure in participants with prenatal alcohol exposure, and to a greater extent in males than females which may suggest attenuation of the expected process of sexual dimorphism of brain structure during typical development.

Pulmonary NO and C18O2 uptake during pressure-induced lung expansion in rabbits.

PubMed

Heller, Hartmut; Schuster, Klaus-Dieter

2007-01-01

In artificially ventilated animals we investigated the dependence of the pulmonary diffusing capacities of nitric oxide (NO) and doubly 18O-labeled carbon dioxide (DLNO, DLC18O2) on lung expansion with respect to ventilator-driven increases in intrapulmonary pressure. For this purpose we applied computerized single-breath experiments to 11 anesthetized paralyzed rabbits (weight 2.8-3.8 kg) at various alveolar volumes (45-72 ml) by studying the almost entire inspiratory limb of the respective pressure/volume curves (intrapulmonary pressure: 6-27 cmH2O). The animals were ventilated with room air, employing a computerized ventilatory servo-system that we designed to maintain mechanical ventilation and to execute the particular lung function tests automatically. Each single-breath maneuver was started from residual volume (13.5+/-2 ml, mean+/-SD) by inflating the rabbit lungs with 35-55 ml indicator gas mixture containing 0.05% NO in N2 or 0.9% C18O2 in N2. Alveolar partial pressures of NO and C18O2 were measured by respiratory mass spectrometry. Values of DLNO and DLC18O2 ranged between 1.55 and 2.49 ml/(mmHg min) and 11.7 and 16.6 ml/(mmHg min), respectively. Linear regression analyses yielded a significant increase in DLNO with simultaneous increase in alveolar volume (P<0.005) and intrapulmonary pressure (P<0.023) whereas DLC18O2 was not improved. Our results suggest that the ventilator-driven lung expansion impaired the C18O2 blood uptake conductance, finally compensating for the beneficial effect of the increase in alveolar volume on DLC18O2 values.

Surface-to-volume ratio mapping of tumor microstructure using oscillating gradient diffusion weighted imaging

PubMed Central

Reynaud, Olivier; Winters, Kerryanne Veronica; Hoang, Dung Minh; Wadghiri, Youssef Zaim; Novikov, Dmitry S; Kim, Sungheon Gene

2015-01-01

Purpose To disentangle the free diffusivity (D0) and cellular membrane restrictions, via their surface-to-volume ratio (S/V), using the frequency-dependence of the diffusion coefficient D(ω), measured in brain tumors in the short diffusion-time regime using oscillating gradients (OGSE). Methods In vivo and ex vivo OGSE experiments were performed on mice bearing the GL261 murine glioma model (n=10) to identify the relevant time/frequency (t/ω) domain where D(ω) linearly decreases with ω−1/2. Parametric maps (S/V, D0) are compared to conventional DWI metrics. The impact of frequency range and temperature (20°C vs. 37°C) on S/V and D0 is investigated ex vivo. Results The validity of the short diffusion-time regime is demonstrated in vivo and ex vivo. Ex vivo measurements confirm that the purely geometric restrictions embodied in S/V are independent from temperature and frequency range, while the temperature dependence of the free diffusivity D0 is similar to that of pure water. Conclusion Our results suggest that D(ω) in the short diffusion-time regime can be used to uncouple the purely geometric restriction effect, such as S/V, from the intrinsic medium diffusivity properties, and provides a non-empirical and objective way to interpret frequency/time-dependent diffusion changes in tumors in terms of objective biophysical tissue parameters. PMID:26207354

Anchoring ZnO Nanoparticles in Nitrogen-Doped Graphene Sheets as a High-Performance Anode Material for Lithium-Ion Batteries.

PubMed

Yuan, Guanghui; Xiang, Jiming; Jin, Huafeng; Wu, Lizhou; Jin, Yanzi; Zhao, Yan

2018-01-10

A novel binary nanocomposite, ZnO/nitrogen-doped graphene (ZnO/NG), is synthesized via a facile solution method. In this prepared ZnO/NG composite, highly-crystalline ZnO nanoparticles with a size of about 10 nm are anchored uniformly on the N-doped graphene nanosheets. Electrochemical properties of the ZnO/NG composite as anode materials are systematically investigated in lithium-ion batteries. Specifically, the ZnO/NG composite can maintain the reversible specific discharge capacity at 870 mAh g -1 after 200 cycles at 100 mA g -1 . Besides the enhanced electronic conductivity provided by interlaced N-doped graphene nanosheets, the excellent lithium storage properties of the ZnO/NG composite can be due to nanosized structure of ZnO particles, shortening the Li⁺ diffusion distance, increasing reaction sites, and buffering the ZnO volume change during the charge/discharge process.

Changes in fitness are associated with changes in hippocampal microstructure and hippocampal volume among older adults.

PubMed

Kleemeyer, Maike Margarethe; Kühn, Simone; Prindle, John; Bodammer, Nils Christian; Brechtel, Lars; Garthe, Alexander; Kempermann, Gerd; Schaefer, Sabine; Lindenberger, Ulman

2016-05-01

This study investigates the effects of fitness changes on hippocampal microstructure and hippocampal volume. Fifty-two healthy participants aged 59-74years with a sedentary lifestyle were randomly assigned to either of two levels of exercise intensity. Training lasted for six months. Physical fitness, hippocampal volumes, and hippocampal microstructure were measured before and after training. Hippocampal microstructure was assessed by mean diffusivity, which inversely reflects tissue density; hence, mean diffusivity is lower for more densely packed tissue. Mean changes in fitness did not differ reliably across intensity levels of training, so data were collapsed across groups. Multivariate modeling of pretest-posttest differences using structural equation modeling (SEM) revealed that individual differences in latent change were reliable for all three constructs. More positive changes in fitness were associated with more positive changes in tissue density (i.e., more negative changes in mean diffusivity), and more positive changes in tissue density were associated with more positive changes in volume. We conclude that fitness-related changes in hippocampal volume may be brought about by changes in tissue density. The relative contributions of angiogenesis, gliogenesis, and/or neurogenesis to changes in tissue density remain to be identified. Copyright © 2015 Elsevier Inc. All rights reserved.

Age-dependent association of thyroid function with brain morphology and microstructural organization: evidence from brain imaging.

PubMed

Chaker, Layal; Cremers, Lotte G M; Korevaar, Tim I M; de Groot, Marius; Dehghan, Abbas; Franco, Oscar H; Niessen, Wiro J; Ikram, M Arfan; Peeters, Robin P; Vernooij, Meike W

2018-01-01

Thyroid hormone (TH) is crucial during neurodevelopment, but high levels of TH have been linked to neurodegenerative disorders. No data on the association of thyroid function with brain imaging in the general population are available. We therefore investigated the association of thyroid-stimulating hormone and free thyroxine (FT4) with magnetic resonance imaging (MRI)-derived total intracranial volume, brain tissue volumes, and diffusion tensor imaging measures of white matter microstructure in 4683 dementia- and stroke-free participants (mean age 60.2, range 45.6-89.9 years). Higher FT4 levels were associated with larger total intracranial volumes (β = 6.73 mL, 95% confidence interval = 2.94-9.80). Higher FT4 levels were also associated with larger total brain and white matter volumes in younger individuals, but with smaller total brain and white matter volume in older individuals (p-interaction 0.02). There was a similar interaction by age for the association of FT4 with mean diffusivity on diffusion tensor imaging (p-interaction 0.026). These results are in line with differential effects of TH during neurodevelopmental and neurodegenerative processes and can improve the understanding of the role of thyroid function in neurodegenerative disorders. Copyright © 2017 Elsevier Inc. All rights reserved.

Capacity Decay Mitigation by Asymmetric Positive/Negative Electrolyte Volumes in Vanadium Redox Flow Batteries.

PubMed

Park, Jong Ho; Park, Jung Jin; Park, O Ok; Yang, Jung Hoon

2016-11-23

Capacity decay in vanadium redox flow batteries during charge-discharge cycling has become an important issue because it lowers the practical energy density of the battery. The battery capacity tends to drop rapidly within the first tens of cycles and then drops more gradually over subsequent cycles during long-term operation. This paper analyzes and discusses the reasons for this early capacity decay. The imbalanced crossover rate of vanadium species was found to remain high until the total difference in vanadium concentration between the positive and negative electrolytes reached almost 1 mol dm -3 . To minimize the initial crossover imbalance, we introduced an asymmetric volume ratio between the positive and negative electrolytes during cell operation. Changing this ratio significantly reduced the capacity fading rate of the battery during the early cycles and improved its capacity retention at steady state. As an example, the practical energy density of the battery increased from 15.5 to 25.2 Wh L -1 simply after reduction of the positive volume by 25 %. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Peak capacity and peak capacity per unit time in capillary and microchip zone electrophoresis.

PubMed

Foley, Joe P; Blackney, Donna M; Ennis, Erin J

2017-11-10

The origins of the peak capacity concept are described and the important contributions to the development of that concept in chromatography and electrophoresis are reviewed. Whereas numerous quantitative expressions have been reported for one- and two-dimensional separations, most are focused on chromatographic separations and few, if any, quantitative unbiased expressions have been developed for capillary or microchip zone electrophoresis. Making the common assumption that longitudinal diffusion is the predominant source of zone broadening in capillary electrophoresis, analytical expressions for the peak capacity are derived, first in terms of migration time, diffusion coefficient, migration distance, and desired resolution, and then in terms of the remaining underlying fundamental parameters (electric field, electroosmotic and electrophoretic mobilities) that determine the migration time. The latter expressions clearly illustrate the direct square root dependence of peak capacity on electric field and migration distance and the inverse square root dependence on solute diffusion coefficient. Conditions that result in a high peak capacity will result in a low peak capacity per unit time and vice-versa. For a given symmetrical range of relative electrophoretic mobilities for co- and counter-electroosmotic species (cations and anions), the peak capacity increases with the square root of the electric field even as the temporal window narrows considerably, resulting in a significant reduction in analysis time. Over a broad relative electrophoretic mobility interval [-0.9, 0.9], an approximately two-fold greater amount of peak capacity can be generated for counter-electroosmotic species although it takes about five-fold longer to do so, consistent with the well-known bias in migration time and resolving power for co- and counter-electroosmotic species. The optimum lower bound of the relative electrophoretic mobility interval [μ r,Z , μ r,A ] that provides the maximum peak capacity per unit time is a simple function of the upper bound, but its direct application is limited to samples with analytes whose electrophoretic mobilities can be varied independently of electroosmotic flow. For samples containing both co- and counter-electroosmotic ions whose electrophoretic mobilities cannot be easily manipulated, comparable levels of peak capacity and peak capacity per unit time for all ions can be obtained by adjusting the EOF to devote the same amount of time to the separation of each class of ions; this corresponds to μ r,Z =-0.5. Copyright © 2017 Elsevier B.V. All rights reserved.

FIELD VALIDATION OF EXPOSURE ASSESSMENT MODELS. VOLUME 1. DATA

EPA Science Inventory

This is the first of two volumes describing work done to evaluate the PAL-DS model, a Gaussian diffusion code modified to account for dry deposition and settling. This first volume describes the experimental techniques employed to dispense, collect, and measure depositing (zinc s...

Anaerobic soil volume as a major controlling factor for soil denitrification and respiration

NASA Astrophysics Data System (ADS)

Reent Köster, Jan; Tong, Bingxin; Grosz, Balázs; Burkart, Stefan; Ruoss, Nicolas; Well, Reinhard

2017-04-01

Gas diffusion in soil is a key variable to control denitrification and its N2O to N2 product ratio since it affects two major proximal denitrification factors, i.e. the concentrations of O2 and of N2O. Gas diffusivity is governed by the structure and the state of water saturation of the pore system. At a given O2 consumption rate decreasing diffusivity causes an enhanced anaerobic soil volume where denitrification can occur. Gas diffusivity is generally quantified as bulk diffusion coefficients that represent the lineal diffusive gas flux through the soil matrix. However, the spatial distribution of respiratory O2 consumption and denitrification - and hence the local concentration of O2 and N2O - is highly non-homogeneous. Knowledge of the anaerobic soil volume fraction (ansvf) has been proposed as a key control on denitrification, and has subsequently been used in many denitrification models. The ansvf has previously been quantified by direct measurement of O2 distribution in individual soil aggregates using microsensors. The measured ansvf corresponded to modelled values based on measured aggregate diffusivity and respiration, but was not yet correlated with measured denitrification rates. In the present ongoing study, we are incubating soil cores amended with nitrate and organic litter in an automated mesocosm system under aerobic as well as anaerobic conditions. An N2 depleted incubation atmosphere and the 15N labeled soil nitrate pool facilitate quantification of the N2 production in the soil by IRMS, and fluxes of N2O and CO2 are monitored via gas chromatography. The ansvf and the measured denitrification and respiration rates will then be used for model validation. During the session we will present first results of this study.

Multimodal MRI in cerebral small vessel disease: its relationship with cognition and sensitivity to change over time.

PubMed

Nitkunan, Arani; Barrick, Tom R; Charlton, Rebecca A; Clark, Chris A; Markus, Hugh S

2008-07-01

Cerebral small vessel disease is the most common cause of vascular dementia. Interest in using MRI parameters as surrogate markers of disease to assess therapies is increasing. In patients with symptomatic sporadic small vessel disease, we determined which MRI parameters best correlated with cognitive function on cross-sectional analysis and which changed over a period of 1 year. Thirty-five patients with lacunar stroke and leukoaraiosis were recruited. They underwent multimodal MRI (brain volume, fluid-attenuated inversion recovery lesion load, lacunar infarct number, fractional anisotropy, and mean diffusivity from diffusion tensor imaging) and neuropsychological testing. Twenty-seven agreed to reattend for repeat MRI and neuropsychology at 1 year. An executive function score correlated most strongly with diffusion tensor imaging (fractional anisotropy histogram, r=-0.640, P=0.004) and brain volume (r=0.501, P=0.034). Associations with diffusion tensor imaging were stronger than with all other MRI parameters. On multiple regression of all imaging parameters, a model that contained brain volume and fractional anisotropy, together with age, gender, and premorbid IQ, explained 74% of the variance of the executive function score (P=0.0001). Changes in mean diffusivity and fractional anisotropy were detectable over the 1-year follow-up; in contrast, no change in other MRI parameters was detectable over this time period. A multimodal MRI model explains a large proportion of the variation in executive function in cerebral small vessel disease. In particular, diffusion tensor imaging correlates best with executive function and is the most sensitive to change. This supports the use of MRI, in particular diffusion tensor imaging, as a surrogate marker in treatment trials.

Serum Methylarginines and Spirometry-Measured Lung Function in Older Adults

PubMed Central

McEvoy, Mark A.; Schofield, Peter W.; Smith, Wayne T.; Agho, Kingsley; Mangoni, Arduino A.; Soiza, Roy L.; Peel, Roseanne; Hancock, Stephen J.; Carru, Ciriaco; Zinellu, Angelo; Attia, John R.

2013-01-01

Rationale Methylarginines are endogenous nitric oxide synthase inhibitors that have been implicated in animal models of lung disease but have not previously been examined for their association with spirometric measures of lung function in humans. Objectives This study measured serum concentrations of asymmetric and symmetric dimethylarginine in a representative sample of older community-dwelling adults and determined their association with spirometric lung function measures. Methods Data on clinical, lifestyle, and demographic characteristics, methylated arginines, and L-arginine (measured using LC-MS/MS) were collected from a population-based sample of older Australian adults from the Hunter Community Study. The five key lung function measures included as outcomes were Forced Expiratory Volume in 1 second, Forced Vital Capacity, Forced Expiratory Volume in 1 second to Forced Vital Capacity ratio, Percent Predicted Forced Expiratory Volume in 1 second, and Percent Predicted Forced Vital Capacity. Measurements and Main Results In adjusted analyses there were statistically significant independent associations between a) higher asymmetric dimethylarginine, lower Forced Expiratory Volume in 1 second and lower Forced Vital Capacity; and b) lower L-arginine/asymmetric dimethylarginine ratio, lower Forced Expiratory Volume in 1 second, lower Percent Predicted Forced Expiratory Volume in 1 second and lower Percent Predicted Forced Vital Capacity. By contrast, no significant associations were observed between symmetric dimethylarginine and lung function. Conclusions After adjusting for clinical, demographic, biochemical, and pharmacological confounders, higher serum asymmetric dimethylarginine was independently associated with a reduction in key measures of lung function. Further research is needed to determine if methylarginines predict the decline in lung function. PMID:23690915

Diffusion of cis-3-methyl-2-pent-2-enyl-cyclopent-2-enone (1); carbon dioxide (2)

NASA Astrophysics Data System (ADS)

Winkelmann, J.

This document is part of Subvolume A `Gases in Gases, Liquids and their Mixtures' of Volume 15 `Diffusion in Gases, Liquids and Electrolytes' of Landolt-Börnstein Group IV `Physical Chemistry'. It is part of the chapter of the chapter `Diffusion in Pure Gases' and contains data on diffusion of (1) cis-3-methyl-2-pent-2-enyl-cyclopent-2-enone; (2) carbon dioxide

Effect of cerebral spinal fluid suppression for diffusional kurtosis imaging.

PubMed

Yang, Alicia W; Jensen, Jens H; Hu, Caixia C; Tabesh, Ali; Falangola, Maria F; Helpern, Joseph A

2013-02-01

To evaluate the cerebral spinal fluid (CSF) partial volume effect on diffusional kurtosis imaging (DKI) metrics in white matter and cortical gray matter. Four healthy volunteers participated in this study. Standard DKI and fluid-attenuated inversion recovery (FLAIR) DKI experiments were performed using a twice-refocused-spin-echo diffusion sequence. The conventional diffusion tensor imaging (DTI) metrics of fractional anisotropy (FA), mean, axial, and radial diffusivity (MD, D[symbol in text], D[symbol in text] together with DKI metrics of mean, axial, and radial kurtosis (MK, K[symbol in text], K[symbol in text], were measured and compared. Single image slices located above the lateral ventricles, with similar anatomical features for each subject, were selected to minimize the effect of CSF from the ventricles. In white matter, differences of less than 10% were observed between diffusion metrics measured with standard DKI and FLAIR-DKI sequences, suggesting minimal CSF contamination. For gray matter, conventional DTI metrics differed by 19% to 52%, reflecting significant CSF partial volume effects. Kurtosis metrics, however, changed by 11% or less, indicating greater robustness with respect to CSF contamination. Kurtosis metrics are less sensitive to CSF partial voluming in cortical gray matter than conventional diffusion metrics. The kurtosis metrics may then be more specific indicators of changes in tissue microstructure, provided the effect sizes for the changes are comparable. Copyright © 2012 Wiley Periodicals, Inc.

Effect of Cross-Linking on Free Volume Properties of PEG Based Thiol-Ene Networks

NASA Astrophysics Data System (ADS)

Ramakrishnan, Ramesh; Vasagar, Vivek; Nazarenko, Sergei

According to the Fox and Loshaek theory, in elastomeric networks, free volume decreases linearly with the cross-link density increase. The aim of this study is to show whether the poly(ethylene glycol) (PEG) based multicomponent thiol-ene elastomeric networks demonstrate this model behavior? Networks with a broad cross-link density range were prepared by changing the ratio of the trithiol crosslinker to PEG dithiol and then UV cured with PEG diene while maintaining 1:1 thiol:ene stoichiometry. Pressure-volume-temperature (PVT) data of the networks was generated from the high pressure dilatometry experiments which was fit using the Simha-Somcynsky Equation-of-State analysis to obtain the fractional free volume of the networks. Using Positron Annihilation Lifetime Spectroscopy (PALS) analysis, the average free volume hole size of the networks was also quantified. The fractional free volume and the average free volume hole size showed a linear change with the cross-link density confirming that the Fox and Loshaek theory can be applied to this multicomponent system. Gas diffusivities of the networks showed a good correlation with free volume. A free volume based model was developed to describe the gas diffusivity trends as a function of cross-link density.

The influence of acid diffusion on the performance of lead-acid cells

NASA Astrophysics Data System (ADS)

Kappus, W.; Bohmann, J.

1983-11-01

A model for the discharge performance of the lead-acid cell is proposed. Diffusion of acid into the porous electrodes, which is connected with diffusio Curves of diffusional polarizations as a function of the discharge time are presented. Calculated discharge capacities show the influence of various pa

Jet Engines as High-Capacity Vacuum Pumps

NASA Technical Reports Server (NTRS)

Wojciechowski, C. J.

1983-01-01

Large diffuser operations envelope and long run times possible. Jet engine driven ejector/diffuser system combines two turbojet engines and variable-area-ratio ejector in two stages. Applications in such industrial proesses as handling corrosive fumes, evaporation of milk and fruit juices, petroleum distillation, and dehydration of blood plasma and penicillin.

Evaluation of multi-modal, multi-site neuroimaging measures in Huntington's disease: Baseline results from the PADDINGTON study☆

PubMed Central

Hobbs, Nicola Z.; Cole, James H.; Farmer, Ruth E.; Rees, Elin M.; Crawford, Helen E.; Malone, Ian B.; Roos, Raymund A.C.; Sprengelmeyer, Reiner; Durr, Alexandra; Landwehrmeyer, Bernhard; Scahill, Rachael I.; Tabrizi, Sarah J.; Frost, Chris

2012-01-01

Background Macro- and micro-structural neuroimaging measures provide valuable information on the pathophysiology of Huntington's disease (HD) and are proposed as biomarkers. Despite theoretical advantages of microstructural measures in terms of sensitivity to pathology, there is little evidence directly comparing the two. Methods 40 controls and 61 early HD subjects underwent 3 T MRI (T1- and diffusion-weighted), as part of the PADDINGTON study. Macrostructural volumetrics were obtained for the whole brain, caudate, putamen, corpus callosum (CC) and ventricles. Microstructural diffusion metrics of fractional anisotropy (FA), mean-, radial- and axial-diffusivity (MD, RD, AD) were computed for white matter (WM), CC, caudate and putamen. Group differences were examined adjusting for age, gender and site. A formal comparison of effect sizes determined which modality and metrics provided a statistically significant advantage over others. Results Macrostructural measures showed decreased regional and global volume in HD (p < 0.001); except the ventricles which were enlarged (p < 0.01). In HD, FA was increased in the deep grey-matter structures (p < 0.001), and decreased in the WM (CC, p = 0.035; WM, p = 0.053); diffusivity metrics (MD, RD, AD) were increased for all brain regions (p < 0.001). The largest effect sizes were for putamen volume, caudate volume and putamen diffusivity (AD, RD and MD); each was significantly larger than those for all other metrics (p < 0.05). Conclusion The highest performing macro- and micro-structural metrics had similar sensitivity to HD pathology quantified via effect sizes. Region-of-interest may be more important than imaging modality, with deep grey-matter regions outperforming the CC and global measures, for both volume and diffusivity. FA appears to be relatively insensitive to disease effects. PMID:24179770

Isotropic non-white matter partial volume effects in constrained spherical deconvolution.

PubMed

Roine, Timo; Jeurissen, Ben; Perrone, Daniele; Aelterman, Jan; Leemans, Alexander; Philips, Wilfried; Sijbers, Jan

2014-01-01

Diffusion-weighted (DW) magnetic resonance imaging (MRI) is a non-invasive imaging method, which can be used to investigate neural tracts in the white matter (WM) of the brain. Significant partial volume effects (PVEs) are present in the DW signal due to relatively large voxel sizes. These PVEs can be caused by both non-WM tissue, such as gray matter (GM) and cerebrospinal fluid (CSF), and by multiple non-parallel WM fiber populations. High angular resolution diffusion imaging (HARDI) methods have been developed to correctly characterize complex WM fiber configurations, but to date, many of the HARDI methods do not account for non-WM PVEs. In this work, we investigated the isotropic PVEs caused by non-WM tissue in WM voxels on fiber orientations extracted with constrained spherical deconvolution (CSD). Experiments were performed on simulated and real DW-MRI data. In particular, simulations were performed to demonstrate the effects of varying the diffusion weightings, signal-to-noise ratios (SNRs), fiber configurations, and tissue fractions. Our results show that the presence of non-WM tissue signal causes a decrease in the precision of the detected fiber orientations and an increase in the detection of false peaks in CSD. We estimated 35-50% of WM voxels to be affected by non-WM PVEs. For HARDI sequences, which typically have a relatively high degree of diffusion weighting, these adverse effects are most pronounced in voxels with GM PVEs. The non-WM PVEs become severe with 50% GM volume for maximum spherical harmonics orders of 8 and below, and already with 25% GM volume for higher orders. In addition, a low diffusion weighting or SNR increases the effects. The non-WM PVEs may cause problems in connectomics, where reliable fiber tracking at the WM-GM interface is especially important. We suggest acquiring data with high diffusion-weighting 2500-3000 s/mm(2), reasonable SNR (~30) and using lower SH orders in GM contaminated regions to minimize the non-WM PVEs in CSD.

Oxygen transfer dynamics and activated sludge floc structure under different sludge retention times at low dissolved oxygen concentrations.

PubMed

Fan, Haitao; Liu, Xiuhong; Wang, Hao; Han, Yunping; Qi, Lu; Wang, Hongchen

2017-02-01

In activated sludge systems, the aeration process consumes the most energy. The energy cost can be dramatically reduced by decreasing the operating dissolved oxygen (DO) concentration. However, low DO may lead to incomplete nitrification and poor settling performance of activated sludge flocs (ASFs). This study investigates oxygen transfer dynamics and settling performances of activated sludge under different sludge retention times (SRTs) and DO conditions using microelectrodes and microscopic techniques. Our experimental results showed that with longer SRTs, treatment capacity and settling performances of activated sludge improved due to smaller floc size and less extracellular polymeric substances (EPS). Long-term low DO conditions produced larger flocs and more EPS per unit sludge, which produced a more extensive anoxic area and led to low oxygen diffusion performance in flocs. Long SRTs mitigated the adverse effects of low DO. According to the microelectrode analysis and fractal dimension determination, smaller floc size and less EPS in the long SRT system led to high oxygen diffusion property and more compact floc structure that caused a drop in the sludge volume index (SVI). In summary, our results suggested that long SRTs of activated sludge can improve the operating performance under low DO conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Combination of microscopic model and VoF-multiphase approach for numerical simulation of nodular cast iron solidification

NASA Astrophysics Data System (ADS)

Subasic, E.; Huang, C.; Jakumeit, J.; Hediger, F.

2015-06-01

The ongoing increase in the size and capacity of state-of-the-art wind power plants is highlighting the need to reduce the weight of critical components, such as hubs, main shaft bearing housings, gear box housings and support bases. These components are manufactured as nodular iron castings (spheroid graphite iron, or SGI). A weight reduction of up to 20% is achievable by optimizing the geometry to minimize volume, thus enabling significant downsizing of wind power plants. One method for enhancing quality control in the production of thick-walled SGI castings, and thus reducing tolerances and, consequently, enabling castings of smaller volume is via a casting simulation of mould filling and solidification based on a combination of microscopic model and VoF-multiphase approach. Coupled fluid flow with heat transport and phase transformation kinetics during solidification is described by partial differential equations and solved using the finite volume method. The flow of multiple phases is described using a volume of fluid approach. Mass conservation equations are solved separately for both liquid and solid phases. At the micro-level, the diffusion-controlled growth model for grey iron eutectic grains by Wetterfall et al. is combined with a growth model for white iron eutectic grains. The micro-solidification model is coupled with macro-transport equations via source terms in the energy and continuity equations. As a first step the methodology was applied to a simple geometry to investigate the impact of mould-filling on the grey-to-white transition prediction in nodular cast iron.

Nation-scale adoption of new medicines by doctors: an application of the Bass diffusion model

PubMed Central

2012-01-01

Background The adoption of new medicines is influenced by a complex set of social processes that have been widely examined in terms of individual prescribers’ information-seeking and decision-making behaviour. However, quantitative, population-wide analyses of how long it takes for new healthcare practices to become part of mainstream practice are rare. Methods We applied a Bass diffusion model to monthly prescription volumes of 103 often-prescribed drugs in Australia (monthly time series data totalling 803 million prescriptions between 1992 and 2010), to determine the distribution of adoption rates. Our aim was to test the utility of applying the Bass diffusion model to national-scale prescribing volumes. Results The Bass diffusion model was fitted to the adoption of a broad cross-section of drugs using national monthly prescription volumes from Australia (median R2 = 0.97, interquartile range 0.95 to 0.99). The median time to adoption was 8.2 years (IQR 4.9 to 12.1). The model distinguished two classes of prescribing patterns – those where adoption appeared to be driven mostly by external forces (19 drugs) and those driven mostly by social contagion (84 drugs). Those driven more prominently by internal forces were found to have shorter adoption times (p = 0.02 in a non-parametric analysis of variance by ranks). Conclusion The Bass diffusion model may be used to retrospectively represent the patterns of adoption exhibited in prescription volumes in Australia, and distinguishes between adoption driven primarily by external forces such as regulation, or internal forces such as social contagion. The eight-year delay between the introduction of a new medicine and the adoption of the prescribing practice suggests the presence of system inertia in Australian prescribing practices. PMID:22876867

Diffusion tensor imaging reveals adolescent binge ethanol-induced brain structural integrity alterations in adult rats that correlate with behavioral dysfunction.

PubMed

Vetreno, Ryan P; Yaxley, Richard; Paniagua, Beatriz; Crews, Fulton T

2016-07-01

Adolescence is characterized by considerable brain maturation that coincides with the development of adult behavior. Binge drinking is common during adolescence and can have deleterious effects on brain maturation because of the heightened neuroplasticity of the adolescent brain. Using an animal model of adolescent intermittent ethanol [AIE; 5.0 g/kg, intragastric, 20 percent EtOH w/v; 2 days on/2 days off from postnatal day (P)25 to P55], we assessed the adult brain structural volumes and integrity on P80 and P220 using diffusion tensor imaging (DTI). While we did not observe a long-term effect of AIE on structural volumes, AIE did reduce axial diffusivity (AD) in the cerebellum, hippocampus and neocortex. Radial diffusivity (RD) was reduced in the hippocampus and neocortex of AIE-treated animals. Prior AIE treatment did not affect fractional anisotropy (FA), but did lead to long-term reductions of mean diffusivity (MD) in both the cerebellum and corpus callosum. AIE resulted in increased anxiety-like behavior and diminished object recognition memory, the latter of which was positively correlated with DTI measures. Across aging, whole brain volumes increased, as did volumes of the corpus callosum and neocortex. This was accompanied by age-associated AD reductions in the cerebellum and neocortex as well as RD and MD reductions in the cerebellum. Further, we found that FA increased in both the cerebellum and corpus callosum as rats aged from P80 to P220. Thus, both age and AIE treatment caused long-term changes to brain structural integrity that could contribute to cognitive dysfunction. © 2015 Society for the Study of Addiction.

White matter involvement in sporadic Creutzfeldt-Jakob disease

PubMed Central

Mandelli, Maria Luisa; DeArmond, Stephen J.; Hess, Christopher P.; Vitali, Paolo; Papinutto, Nico; Oehler, Abby; Miller, Bruce L.; Lobach, Irina V.; Bastianello, Stefano; Geschwind, Michael D.; Henry, Roland G.

2014-01-01

Sporadic Creutzfeldt-Jakob disease is considered primarily a disease of grey matter, although the extent of white matter involvement has not been well described. We used diffusion tensor imaging to study the white matter in sporadic Creutzfeldt-Jakob disease compared to healthy control subjects and to correlated magnetic resonance imaging findings with histopathology. Twenty-six patients with sporadic Creutzfeldt-Jakob disease and nine age- and gender-matched healthy control subjects underwent volumetric T1-weighted and diffusion tensor imaging. Six patients had post-mortem brain analysis available for assessment of neuropathological findings associated with prion disease. Parcellation of the subcortical white matter was performed on 3D T1-weighted volumes using Freesurfer. Diffusion tensor imaging maps were calculated and transformed to the 3D-T1 space; the average value for each diffusion metric was calculated in the total white matter and in regional volumes of interest. Tract-based spatial statistics analysis was also performed to investigate the deeper white matter tracts. There was a significant reduction of mean (P = 0.002), axial (P = 0.0003) and radial (P = 0.0134) diffusivities in the total white matter in sporadic Creutzfeldt-Jakob disease. Mean diffusivity was significantly lower in most white matter volumes of interest (P < 0.05, corrected for multiple comparisons), with a generally symmetric pattern of involvement in sporadic Creutzfeldt-Jakob disease. Mean diffusivity reduction reflected concomitant decrease of both axial and radial diffusivity, without appreciable changes in white matter anisotropy. Tract-based spatial statistics analysis showed significant reductions of mean diffusivity within the white matter of patients with sporadic Creutzfeldt-Jakob disease, mainly in the left hemisphere, with a strong trend (P = 0.06) towards reduced mean diffusivity in most of the white matter bilaterally. In contrast, by visual assessment there was no white matter abnormality either on T2-weighted or diffusion-weighted images. Widespread reduction in white matter mean diffusivity, however, was apparent visibly on the quantitative attenuation coefficient maps compared to healthy control subjects. Neuropathological analysis showed diffuse astrocytic gliosis and activated microglia in the white matter, rare prion deposition and subtle subcortical microvacuolization, and patchy foci of demyelination with no evident white matter axonal degeneration. Decreased mean diffusivity on attenuation coefficient maps might be associated with astrocytic gliosis. We show for the first time significant global reduced mean diffusivity within the white matter in sporadic Creutzfeldt-Jakob disease, suggesting possible primary involvement of the white matter, rather than changes secondary to neuronal degeneration/loss. PMID:25367029

Apparent diffusion coefficient measurement in glioma: Influence of region-of-interest determination methods on apparent diffusion coefficient values, interobserver variability, time efficiency, and diagnostic ability.

PubMed

Han, Xu; Suo, Shiteng; Sun, Yawen; Zu, Jinyan; Qu, Jianxun; Zhou, Yan; Chen, Zengai; Xu, Jianrong

2017-03-01

To compare four methods of region-of-interest (ROI) placement for apparent diffusion coefficient (ADC) measurements in distinguishing low-grade gliomas (LGGs) from high-grade gliomas (HGGs). Two independent readers measured ADC parameters using four ROI methods (single-slice [single-round, five-round and freehand] and whole-volume) on 43 patients (20 LGGs, 23 HGGs) who had undergone 3.0 Tesla diffusion-weighted imaging and time required for each method of ADC measurements was recorded. Intraclass correlation coefficients (ICCs) were used to assess interobserver variability of ADC measurements. Mean and minimum ADC values and time required were compared using paired Student's t-tests. All ADC parameters (mean/minimum ADC values of three single-slice methods, mean/minimum/standard deviation/skewness/kurtosis/the10 th and 25 th percentiles/median/maximum of whole-volume method) were correlated with tumor grade (low versus high) by unpaired Student's t-tests. Discriminative ability was determined by receiver operating characteristic curves. All ADC measurements except minimum, skewness, and kurtosis of whole-volume ROI differed significantly between LGGs and HGGs (all P < 0.05). Mean ADC value of single-round ROI had the highest effect size (0.72) and the greatest areas under the curve (0.872). Three single-slice methods had good to excellent ICCs (0.67-0.89) and the whole-volume method fair to excellent ICCs (0.32-0.96). Minimum ADC values differed significantly between whole-volume and single-round ROI (P = 0.003) and, between whole-volume and five-round ROI (P = 0.001). The whole-volume method took significantly longer than all single-slice methods (all P < 0.001). ADC measurements are influenced by ROI determination methods. Whole-volume histogram analysis did not yield better results than single-slice methods and took longer. Mean ADC value derived from single-round ROI is the most optimal parameter for differentiating LGGs from HGGs. 3 J. Magn. Reson. Imaging 2017;45:722-730. © 2016 International Society for Magnetic Resonance in Medicine.

Synthesis, Characterization and Performance of Cathodes for Lithium Ion Batteries

NASA Astrophysics Data System (ADS)

Zhu, Jianxin

Lithium ion batteries provide a high energy density, higher voltage as well as a long shelf life compared to traditionally used lead acid, NiMH and NiCd batteries. Thus, they are a very promising energy storage system for our daily life. As one of the most important components in a battery, cathode materials have been investigated intensively in recent years as they play a key role in determining the cell voltage and discharge capacity in a battery. Both layered Li(Ni1/3Co1/3Mn1/3)O 2 (NCM) and olivine-structured LiFePO4 (LFP) materials are promising cathode candidates. However, these cathodes also have some disadvantages that have hindered further commercialization. The main issue with NCM is its rapid performance decay upon cycling. In addition, LFP is hindered by a low rate capacity and low lithium ion diffusivity. We studied the crystal growth behavior and performance of both Li(Ni 1/3Co1/3Mn1/3)O2 and LiFePO4 cathodes in order to develop synthesis-structure-function relationships. Three different crystal growth behaviors were observed for the NCM annealing process: surface, volume and grain boundary diffusion. Further exploration of the mechanism of NCM performance decay revealed that microstructural changes were related to the strain accommodation ability in this system and that nanostructured materials were more stable during cycling. In the LFP synthesis, we observed both oriented attachment (OA) and Ostwald ripening (OR) during growth in a triethylene-glycol system. Both polycrystalline and single crystalline particles evolved as a function of a time-dependent pH change. Thus, the lithium ion diffusion rate of LiFePO4 was improved by tailoring the morphology and size though our modification of the precursor environment, revealing that polycrystalline LFP displayed better performance than single crystalline particles. Finally, the electronic conductivity of LiFePO4 was successfully increased via a polymer solution coating method. By producing more uniform, thin and coherent coatings on LiFePO4 particles, we were able to produce batteries with significantly less carbon (i.e., 0.41 wt.%) while has comparable performance (discharge capacity of 80mAh/g at 2C) compared to traditionally synthesized carbon-coated LiFePO4 with higher carbon loadings (ca. 2.64 wt.%). This will enable us to produce batteries with higher active material loading and therefore, significantly larger energy densities.

Brain microvascular function during cardiopulmonary bypass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sorensen, H.R.; Husum, B.; Waaben, J.

1987-11-01

Emboli in the brain microvasculature may inhibit brain activity during cardiopulmonary bypass. Such hypothetical blockade, if confirmed, may be responsible for the reduction of cerebral metabolic rate for glucose observed in animals subjected to cardiopulmonary bypass. In previous studies of cerebral blood flow during bypass, brain microcirculation was not evaluated. In the present study in animals (pigs), reduction of the number of perfused capillaries was estimated by measurements of the capillary diffusion capacity for hydrophilic tracers of low permeability. Capillary diffusion capacity, cerebral blood flow, and cerebral metabolic rate for glucose were measured simultaneously by the integral method, different tracersmore » being used with different circulation times. In eight animals subjected to normothermic cardiopulmonary bypass, and seven subjected to hypothermic bypass, cerebral blood flow, cerebral metabolic rate for glucose, and capillary diffusion capacity decreased significantly: cerebral blood flow from 63 to 43 ml/100 gm/min in normothermia and to 34 ml/100 gm/min in hypothermia and cerebral metabolic rate for glucose from 43.0 to 23.0 mumol/100 gm/min in normothermia and to 14.1 mumol/100 gm/min in hypothermia. The capillary diffusion capacity declined markedly from 0.15 to 0.03 ml/100 gm/min in normothermia but only to 0.08 ml/100 gm/min in hypothermia. We conclude that the decrease of cerebral metabolic rate for glucose during normothermic cardiopulmonary bypass is caused by interruption of blood flow through a part of the capillary bed, possibly by microemboli, and that cerebral blood flow is an inadequate indicator of capillary blood flow. Further studies must clarify why normal microvascular function appears to be preserved during hypothermic cardiopulmonary bypass.« less

Lifetime Occupational Exposure to Dusts, Gases and Fumes Is Associated with Bronchitis Symptoms and Higher Diffusion Capacity in COPD Patients

PubMed Central

Rodríguez, Esther; Ferrer, Jaume; Zock, Jan-Paul; Serra, Ignasi; Antó, Josep M.; de Batlle, Jordi; Kromhout, Hans; Vermeulen, Roel; Donaire-González, David; Benet, Marta; Balcells, Eva; Monsó, Eduard; Gayete, Angel; Garcia-Aymerich, Judith

2014-01-01

Background Occupational exposure to dusts, gases and fumes has been associated with reduced FEV1 and sputum production in COPD patients. The effect of occupational exposure on other characteristics of COPD, especially those reflecting emphysema, has not been studied in these patients. Methods We studied 338 patients hospitalized for a first exacerbation of COPD in 9 Spanish hospitals, obtaining full occupational history in a face-to-face interview; job codes were linked to a job exposure matrix for semi-quantitative estimation of exposure to mineral/biological dust, and gases/fumes for each job held. Patients underwent spirometry, diffusing capacity testing and analysis of gases in stable conditions. Quality of life, dyspnea and chronic bronchitis symptoms were determined with a questionnaire interview. A high- resolution CT scan was available in 133 patients. Results 94% of the patients included were men, with a mean age of 68(8.5) years and a mean FEV1% predicted 52 (16). High exposure to gases or fumes was associated with chronic bronchitis, and exposure to mineral dust and gases/fumes was associated with higher scores for symptom perception in the St. George’s questionnaire. No occupational agent was associated with a lower FEV1. High exposure to all occupational agents was associated with better lung diffusion capacity, in long-term quitters. In the subgroup with CT data, patients with emphysema had 18% lower DLCO compared to those without emphysema. Conclusions In our cohort of COPD patients, high exposure to gases or fumes was associated with chronic bronchitis, and high exposure to all occupational agents was consistently associated with better diffusion capacity in long-term quitters. PMID:24516659

Distribution of selected volatile organic compounds determined with water-to-vapor diffusion samplers at the interface between ground water and surface water, Centredale Manor site, North Providence, Rhode Island, September 1999

USGS Publications Warehouse

Church, Peter E.; Lyford, Forest P.; Clifford, Scott

2000-01-01

Volatile organic compounds are present in soils and ground water at the Centredale Manor Superfund Site in North Providence, Rhode Island. In September 1999, water-to-vapor diffusion samplers were placed in the bottom sediments of waterways adjacent to the site to identify possible contaminated ground-water discharge areas. The approximate12-acre site is a narrow stretch of land between the eastern bank of the Woonasquatucket River, downstream from the U.S. Route 44 bridge and a former mill raceway. The samplers were placed along a 2,250-foot reach of the Woonasquatucket River, in the former mill raceway several hundred feet to the east and parallel to the river, and in a cross channel between the river and former mill raceway. Volatile organic compounds were detected in 84 of the 104 water-to-vapor diffusion samplers retrieved. Trichloroethylene and tetrachloro-ethylene were the principal volatile organic compounds detected. The highest vapor concentrations measured for these two chemicals were from diffusion samplers located along an approximate 100-foot reach of the Woonasquatucket River about 500 feet downstream of the bridge; here trichloroethylene and tetrachloroethylene vapor concentrations ranged from about 2,000 to 180,000 and 1,600 to 1,400,000 parts per billion by volume, respectively. Upstream and downstream from this reach and along the former mill raceway, trichloroethylene and tetrachloroethylene vapor concentrations from the diffusion samples were generally less than 100 parts per billion by volume. Along the lower reaches of the river and mill raceway, however, and in the cross channel, vapor concentrations of trichloroethylene exceeded 100 parts per billion by volume and tetrachloroethylene exceeded 1,000 parts per billion by volume in several diffusion samples. Although diffusion sample vapor concentrations are higher than water concentrations in surface waters and in ground water, and they should only be interpreted qualitatively as relative values, these values provide important information as to potential discharge areas of contaminants.

Water transport, free volume, and polymer dynamics in crosslinked polymer networks

NASA Astrophysics Data System (ADS)

Frieberg, Bradley; Soles, Christopher

Many technologies rely on amorphous polymer membranes that selectively transport small molecules or ions, which has led to a significant scientific interest in elucidating the mechanisms of transport. A recurring theme among several different materials systems is that free volume and polymer chain dynamics facilitate transport. In order to understand the interplay between free volume, transport and polymer dynamics we quantify these properties for a model epoxy network. The epoxy chemistry allows for systematically varying both the structural rigidity of the network as well as the cross-link density. We performed positron annihilation lifetime spectroscopy measurements to characterize the unoccupied volume and correlated the unoccupied volume to the equilibrium moisture uptake and effective diffusion coefficient. We have recently extended this work to include polymer dynamics measured by quasi-elastic neutron scattering on the NIST High Flux Backscatter Spectrometer. These measurements reveal a strong correlation between the MSD and the transport kinetics, which was even stronger than the correlation previously observed between free volume and water diffusion. These observations challenge previous theories that suggest free volume governs transport.

Efficacy of N-Acetylcysteine in Idiopathic Pulmonary Fibrosis

PubMed Central

Sun, Tong; Liu, Jing; Zhao, De Wei

2016-01-01

Abstract There are a number of conflicting reports describing the clinical outcomes of using N-acetylcysteine for the treatment of idiopathic pulmonary fibrosis. We have, therefore, performed a meta-analysis to evaluate the efficacy of N-acetylcysteine, compared with control, for the treatment of idiopathic pulmonary fibrosis. Original controlled clinical trials evaluating the efficacy of N-acetylcysteine for the treatment of idiopathic pulmonary fibrosis were included in the analysis. Searches for relevant articles were carried out in July 2014 by 2 independent researchers using PubMed, Embase, Cochrane Central, and Google Scholar. Change in forced vital capacity, change in percentage of predicted vital capacity, change in percentage of predicted carbon monoxide diffusing capacity, changes in 6 minutes walking test distance, rate of adverse events, and rate of death were expressed as outcomes using RevMan 5.0.1. Five trials, with a total of 564 patients, were included in this meta-analysis. The meta-analysis showed that the control group had significant decreases in percentage of predicted vital capacity (standardized mean difference [SMD] = 0.37; 95% confidence interval [CI]: 0.13 to −0.62; P = 0.003) and 6 minutes walking test distance (SMD = 0.25; 95% CI: 0.02–0.48; P = 0.04). There were no statistically significant differences in forced vital capacity (SMD = 0.07; 95% CI: −0.13–0.27; P = 0.52), percentage of predicted carbon monoxide diffusing capacity (SMD = 0.12; 95% CI: −0.06–0.30; P = 0.18), rates of adverse events (odd ratio = 4.50; 95% CI: 0.19–106.41; P = 0.35), or death rates (odd ratio = 1.79; 95% CI: 0.3–5.12; P = 0.28) between the N-acetylcysteine group and the control group. N-Acetylcysteine was found to have a significant effect only on decreases in percentage of predicted vital capacity and 6 minutes walking test distance. N-acetylcysteine showed no beneficial effect on changes in forced vital capacity, changes in predicted carbon monoxide diffusing capacity, rates of adverse events, or death rates. PMID:27175674

Efficacy of N-Acetylcysteine in Idiopathic Pulmonary Fibrosis: A Systematic Review and Meta-Analysis.

PubMed

Sun, Tong; Liu, Jing; Zhao, De Wei

2016-05-01

There are a number of conflicting reports describing the clinical outcomes of using N-acetylcysteine for the treatment of idiopathic pulmonary fibrosis. We have, therefore, performed a meta-analysis to evaluate the efficacy of N-acetylcysteine, compared with control, for the treatment of idiopathic pulmonary fibrosis.Original controlled clinical trials evaluating the efficacy of N-acetylcysteine for the treatment of idiopathic pulmonary fibrosis were included in the analysis. Searches for relevant articles were carried out in July 2014 by 2 independent researchers using PubMed, Embase, Cochrane Central, and Google Scholar. Change in forced vital capacity, change in percentage of predicted vital capacity, change in percentage of predicted carbon monoxide diffusing capacity, changes in 6 minutes walking test distance, rate of adverse events, and rate of death were expressed as outcomes using RevMan 5.0.1.Five trials, with a total of 564 patients, were included in this meta-analysis. The meta-analysis showed that the control group had significant decreases in percentage of predicted vital capacity (standardized mean difference [SMD] = 0.37; 95% confidence interval [CI]: 0.13 to -0.62; P = 0.003) and 6 minutes walking test distance (SMD = 0.25; 95% CI: 0.02-0.48; P = 0.04). There were no statistically significant differences in forced vital capacity (SMD = 0.07; 95% CI: -0.13-0.27; P = 0.52), percentage of predicted carbon monoxide diffusing capacity (SMD = 0.12; 95% CI: -0.06-0.30; P = 0.18), rates of adverse events (odd ratio = 4.50; 95% CI: 0.19-106.41; P = 0.35), or death rates (odd ratio = 1.79; 95% CI: 0.3-5.12; P = 0.28) between the N-acetylcysteine group and the control group.N-Acetylcysteine was found to have a significant effect only on decreases in percentage of predicted vital capacity and 6 minutes walking test distance. N-acetylcysteine showed no beneficial effect on changes in forced vital capacity, changes in predicted carbon monoxide diffusing capacity, rates of adverse events, or death rates.

[The Contribution of Vascular Capacity and Blood Volume to Maintain Stable Blood Circulation during General Anesthesia].

PubMed

Shigemi, Kenji

2016-05-01

To maintain proper cardiac preload is one of the most effective procedures for the systemic circulation remaining stable. In particular, the balance between vascular capacity and total blood volume must be maintained within appropriate range by the administration of fluids, blood and/or vasoactive drugs with mean circulatory filling pressure (Pmcf), central venous pressure (CVP) or stroke volume variation (SVV). End-diastolic left ventricular volume (Ved) is theoretically the best index of cardiac preload; however, without transesophageal echocardbalanceiogram we cannot directly monitor Ved during anesthesia. The infused fluid volume remaining in intravascular space, the vascular capacity controlled by autonomic nervous system and/or vasoactive agents, and the unstressed blood volume properly mobilized to excess blood volume are the crucial factors to maintain cardiac output The knowledge of vascular physiology contribute the decision making to manipulate such factors to control blood circulation during general anesthesia. For example, CVP is usually maintained in the narrow range and seems to be stable; however, it must be changed just after the circulatory disturbances, such as acute bleeding, blood transfusion, and fluid infusion, and followed by gradual returning to initial value, because of the solid mechanism to preserve cardiac output

Chloroplast Osmotic Adjustment and Water Stress Effects on Photosynthesis 1

PubMed Central

Gupta, Ashima Sen; Berkowitz, Gerald A.

1988-01-01

Previous studies have suggested that chloroplast stromal volume reduction may mediate the inhibition of photosynthesis under water stress. In this study, the effects of spinach (Spinacia oleracea, var `Winter Bloomsdale') plant water deficits on chloroplast photosynthetic capacity, solute concentrations in chloroplasts, and chloroplast volume were studied. In situ (gas exchange) and in vitro measurements indicated that chloroplast photosynthetic capacity was maintained during initial leaf water potential (Ψw) and relative water content (RWC) decline. During the latter part of the stress period, photosynthesis dropped precipitously. Chloroplast stromal volume apparently remained constant during the initial period of decline in RWC, but as leaf Ψw reached −1.2 megapascals, stromal volume began to decline. The apparent maintenance of stromal volume over the initial RWC decline during a stress cycle suggested that chloroplasts are capable of osmotic adjustment in response to leaf water deficits. This hypothesis was confirmed by measuring chloroplast solute levels, which increased during stress. The results of these experiments suggest that stromal volume reduction in situ may be associated with loss of photosynthetic capacity and that one mechanism of photosynthetic acclimation to low Ψw may involve stromal volume maintenance. PMID:16666266

Mo-doped SnO2 mesoporous hollow structured spheres as anode materials for high-performance lithium ion batteries

NASA Astrophysics Data System (ADS)

Wang, Xuekun; Li, Zhaoqiang; Zhang, Zhiwei; Li, Qun; Guo, Enyan; Wang, Chengxiang; Yin, Longwei

2015-02-01

We designed a facile infiltration route to synthesize mesoporous hollow structured Mo doped SnO2 using silica spheres as templates. It is observed that Mo is uniformly incorporated into SnO2 lattice in the form of Mo6+. The as-prepared mesoporous Mo-doped SnO2 LIBs anodes exhibit a significantly improved electrochemical performance with good cycling stability, high specific capacity and high rate capability. The mesoporous hollow Mo-doped SnO2 sample with 14 at% Mo doping content displays a specific capacity of 801 mA h g-1 after 60 cycles at a current density of 100 mA g-1, about 1.66 times higher than that of the pure SnO2 hollow sample. In addition, even if the current density is as high as 1600 mA g-1 after 60 cycles, it could still retain a stable specific capacity of 530 mA h g-1, exhibiting an extraordinary rate capability. The greatly improved electrochemical performance of the Mo-doped mesoporous hollow SnO2 sample could be attributed to the following factors. The large surface area and hollow structure can significantly enhance structural integrity by acting as mechanical buffer, effectively alleviating the volume changes generated during the lithiation/delithiation process. The incorporation of Mo into the lattice of SnO2 improves charge transfer kinetics and results in a faster Li+ diffusion rate during the charge-discharge process.

Binder-free ZnO@ZnSnO3 quantum dots core-shell nanorod array anodes for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Tan, Hsiang; Cho, Hsun-Wei; Wu, Jih-Jen

2018-06-01

In this work, ZnSnO3 quantum dots (QDs), instead of commonly used conductive carbon, are grown on the ZnO nanorod (NR) array to construct the binder-free ZnO@ZnSnO3 QDs core-shell NR array electrode on carbon cloth for lithium-ion battery. The ZnO@ZnSnO3 QDs core-shell NR array electrode exhibits excellent lithium storage performance with an improved cycling performance and superior rate capability compared to the ZnO NR array electrode. At a current density of 200 mAg-1, 15.8% capacity loss is acquired in the ZnO@ZnSnO3 QDs core-shell NR array electrode after 110 cycles with capacity retention of 1073 mAhg-1. Significant increases in reversible capacities from 340 to 545 mAhg-1 and from 95 to 390 mAhg-1 at current densities of 1000 and 2000 mAg-1, respectively, are achieved as the ZnO NR arrays are coated with the ZnSnO3 QD shells. The remarkably improved electrochemical performances result from that the configuration of binder-free ZnO@ZnSnO3 QDs core-shell NR array electrode not only facilitates the charge transfer through the solid electrolyte interface and the electronic/ionic conduction boundary as well as lithium ion diffusion but also effectively accommodates the volume change during repeated charge/discharge processes.

Sustained diffusion reversal with in-bore reperfusion in monkey stroke models: Confirmed by prospective magnetic resonance imaging

PubMed Central

Yi, Kyung Sik; Choi, Chi-Hoon; Lee, Sang-Rae; Lee, Hong Jun; Lee, Youngjeon; Jeong, Kang-Jin; Hwang, Jinwoo; Chang, Kyu-Tae

2016-01-01

Although early diffusion lesion reversal after recanalization treatment of acute ischaemic stroke has been observed in clinical settings, the reversibility of lesions observed by diffusion-weighted imaging remains controversial. Here, we present consistent observations of sustained diffusion lesion reversal after transient middle cerebral artery occlusion in a monkey stroke model. Seven rhesus macaques were subjected to endovascular transient middle cerebral artery occlusion with in-bore reperfusion confirmed by repeated prospective diffusion-weighted imaging. Early diffusion lesion reversal was defined as lesion reversal at 3 h after reperfusion. Sustained diffusion lesion reversal was defined as the difference between the ADC-derived pre-reperfusion maximal ischemic lesion volume (ADCD-P Match) and the lesion on 4-week follow-up FLAIR magnetic resonance imaging. Diffusion lesions were spatiotemporally assessed using a 3-D voxel-based quantitative technique. The ADCD-P Match was 9.7 ± 6.0% (mean ± SD) and the final infarct was 1.2–6.0% of the volume of the ipsilateral hemisphere. Early diffusion lesion reversal and sustained diffusion lesion reversal were observed in all seven animals, and the calculated percentages compared with their ADCD-P Match ranged from 8.3 to 51.9% (mean ± SD, 26.9 ± 15.3%) and 41.7–77.8% (mean ± SD, 65.4 ± 12.2%), respectively. Substantial sustained diffusion lesion reversal and early reversal were observed in all animals in this monkey model of transient focal cerebral ischaemia. PMID:27401804

Designing High Capacity, Stable Lithium-Manganese Oxide Insertion Electrodes with First Principles Computations

NASA Astrophysics Data System (ADS)

Reed, John; van der Ven, Anton; Ceder, Gerbrand

2001-03-01

The viability of rechargeable lithium batteries in many applications hinges on finding electrode materials with high capacity, excellent chemical and phase stability, and low cost. LiCoO_2, the intercalation oxide currently used is too expensive and unsafe for large-scale batteries. Manganese oxides are a possible low cost alternative, but spinel LiMn_2O _4, the common form of the material, has too low a capacity and some stability problems. Recently, layered LiMnO _2, isostructural to LiCoO _2, has been synthesized. After a few battery cycles this material irreversibly transforms to a spinel structure, with loss of battery capacity. In this work we use Density Functional Theory to investigate why LiMnO2 transforms so rapidly to spinel but LiCoO 2 does not, even though both are known to be thermodynamically unstable towards this transformation. We find that the difference between the two compound is due to remarkably rapid diffusion of Mn ^3+. Diffusion of Mn^3+ occurs by disproportionation into Mn ^2+ an Mn ^4+ which gives the system a remarkable flexibility in its hybridization with the oxygen ions, even at the saddle point for diffusion. This knowledge has now been used to suggest compositional modifications of LiMnO 2 which slow down or even prevent the transformation to a spinel.

Protein diffusion along DNA: on the effect of roadblocks and crowders

NASA Astrophysics Data System (ADS)

Krepel, Dana; Levy, Yaakov

2016-12-01

Rapid recognition by a protein of its DNA target site is achieved through a combination of one- and three-dimensional (1D and 3D) diffusion, which allows efficient scanning of the many alternative sites. This facilitated diffusion mechanism is expected to be affected by cellular conditions, particularly crowding, given that up to 40% of the total cellular volume may by occupied by macromolecules. Both experimental and theoretical studies showed that crowding particles can enhance facilitated diffusion and accelerate search kinetics. This effect may originate from crowding forcing a trade-off between 3D and 1D diffusion. In this study, using coarse-grained molecular dynamic simulations, we investigate how the molecular properties of the crowders may modulate the effect exerted by crowding on a searcher protein. We show that crowders with an affinity to the DNA are less effective search facilitators than particles whose contribution is solely entropic. Crowders that have affinity to DNA may occupy DNA sites and thereby function as obstacles or roadblocks that slow down the searcher protein, and they may also produce a smaller excluded volume effect and so reduce usage of the hopping searching mode in favor of less-effective 3D diffusion in the bulk. We discuss how strong repulsive interactions between the crowding particles themselves may affect the overall dynamics of the crowders and their excluded volume effect. Our study shows that search kinetics and its mechanism are modulated not only by salt concentration and crowding occupancy, but also by the properties of the crowding particles.

Dual control of flow field heterogeneity and immobile porosity on non-Fickian transport in Berea sandstone

NASA Astrophysics Data System (ADS)

Gjetvaj, Filip; Russian, Anna; Gouze, Philippe; Dentz, Marco

2015-10-01

Both flow field heterogeneity and mass transfer between mobile and immobile domains have been studied separately for explaining observed anomalous transport. Here we investigate non-Fickian transport using high-resolution 3-D X-ray microtomographic images of Berea sandstone containing microporous cement with pore size below the setup resolution. Transport is computed for a set of representative elementary volumes and results from advection and diffusion in the resolved macroporosity (mobile domain) and diffusion in the microporous phase (immobile domain) where the effective diffusion coefficient is calculated from the measured local porosity using a phenomenological model that includes a porosity threshold (ϕθ) below which diffusion is null and the exponent n that characterizes tortuosity-porosity power-law relationship. We show that both flow field heterogeneity and microporosity trigger anomalous transport. Breakthrough curve (BTC) tailing is positively correlated to microporosity volume and mobile-immobile interface area. The sensitivity analysis showed that the BTC tailing increases with the value of ϕθ, due to the increase of the diffusion path tortuosity until the volume of the microporosity becomes negligible. Furthermore, increasing the value of n leads to an increase in the standard deviation of the distribution of effective diffusion coefficients, which in turn results in an increase of the BTC tailing. Finally, we propose a continuous time random walk upscaled model where the transition time is the sum of independently distributed random variables characterized by specific distributions. It allows modeling a 1-D equivalent macroscopic transport honoring both the control of the flow field heterogeneity and the multirate mass transfer between mobile and immobile domains.

A Hough transform global probabilistic approach to multiple-subject diffusion MRI tractography.

PubMed

Aganj, Iman; Lenglet, Christophe; Jahanshad, Neda; Yacoub, Essa; Harel, Noam; Thompson, Paul M; Sapiro, Guillermo

2011-08-01

A global probabilistic fiber tracking approach based on the voting process provided by the Hough transform is introduced in this work. The proposed framework tests candidate 3D curves in the volume, assigning to each one a score computed from the diffusion images, and then selects the curves with the highest scores as the potential anatomical connections. The algorithm avoids local minima by performing an exhaustive search at the desired resolution. The technique is easily extended to multiple subjects, considering a single representative volume where the registered high-angular resolution diffusion images (HARDI) from all the subjects are non-linearly combined, thereby obtaining population-representative tracts. The tractography algorithm is run only once for the multiple subjects, and no tract alignment is necessary. We present experimental results on HARDI volumes, ranging from simulated and 1.5T physical phantoms to 7T and 4T human brain and 7T monkey brain datasets. Copyright © 2011 Elsevier B.V. All rights reserved.

Mixing model with multi-particle interactions for Lagrangian simulations of turbulent mixing

NASA Astrophysics Data System (ADS)

Watanabe, T.; Nagata, K.

2016-08-01

We report on the numerical study of the mixing volume model (MVM) for molecular diffusion in Lagrangian simulations of turbulent mixing problems. The MVM is based on the multi-particle interaction in a finite volume (mixing volume). A priori test of the MVM, based on the direct numerical simulations of planar jets, is conducted in the turbulent region and the interfacial layer between the turbulent and non-turbulent fluids. The results show that the MVM predicts well the mean effects of the molecular diffusion under various numerical and flow parameters. The number of the mixing particles should be large for predicting a value of the molecular diffusion term positively correlated to the exact value. The size of the mixing volume relative to the Kolmogorov scale η is important in the performance of the MVM. The scalar transfer across the turbulent/non-turbulent interface is well captured by the MVM especially with the small mixing volume. Furthermore, the MVM with multiple mixing particles is tested in the hybrid implicit large-eddy-simulation/Lagrangian-particle-simulation (LES-LPS) of the planar jet with the characteristic length of the mixing volume of O(100η). Despite the large mixing volume, the MVM works well and decays the scalar variance in a rate close to the reference LES. The statistics in the LPS are very robust to the number of the particles used in the simulations and the computational grid size of the LES. Both in the turbulent core region and the intermittent region, the LPS predicts a scalar field well correlated to the LES.

Order of accuracy of QUICK and related convection-diffusion schemes

NASA Technical Reports Server (NTRS)

Leonard, B. P.

1993-01-01

This report attempts to correct some misunderstandings that have appeared in the literature concerning the order of accuracy of the QUICK scheme for steady-state convective modeling. Other related convection-diffusion schemes are also considered. The original one-dimensional QUICK scheme written in terms of nodal-point values of the convected variable (with a 1/8-factor multiplying the 'curvature' term) is indeed a third-order representation of the finite volume formulation of the convection operator average across the control volume, written naturally in flux-difference form. An alternative single-point upwind difference scheme (SPUDS) using node values (with a 1/6-factor) is a third-order representation of the finite difference single-point formulation; this can be written in a pseudo-flux difference form. These are both third-order convection schemes; however, the QUICK finite volume convection operator is 33 percent more accurate than the single-point implementation of SPUDS. Another finite volume scheme, writing convective fluxes in terms of cell-average values, requires a 1/6-factor for third-order accuracy. For completeness, one can also write a single-point formulation of the convective derivative in terms of cell averages, and then express this in pseudo-flux difference form; for third-order accuracy, this requires a curvature factor of 5/24. Diffusion operators are also considered in both single-point and finite volume formulations. Finite volume formulations are found to be significantly more accurate. For example, classical second-order central differencing for the second derivative is exactly twice as accurate in a finite volume formulation as it is in single-point.

Mixing model with multi-particle interactions for Lagrangian simulations of turbulent mixing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watanabe, T., E-mail: watanabe.tomoaki@c.nagoya-u.jp; Nagata, K.

We report on the numerical study of the mixing volume model (MVM) for molecular diffusion in Lagrangian simulations of turbulent mixing problems. The MVM is based on the multi-particle interaction in a finite volume (mixing volume). A priori test of the MVM, based on the direct numerical simulations of planar jets, is conducted in the turbulent region and the interfacial layer between the turbulent and non-turbulent fluids. The results show that the MVM predicts well the mean effects of the molecular diffusion under various numerical and flow parameters. The number of the mixing particles should be large for predicting amore » value of the molecular diffusion term positively correlated to the exact value. The size of the mixing volume relative to the Kolmogorov scale η is important in the performance of the MVM. The scalar transfer across the turbulent/non-turbulent interface is well captured by the MVM especially with the small mixing volume. Furthermore, the MVM with multiple mixing particles is tested in the hybrid implicit large-eddy-simulation/Lagrangian-particle-simulation (LES–LPS) of the planar jet with the characteristic length of the mixing volume of O(100η). Despite the large mixing volume, the MVM works well and decays the scalar variance in a rate close to the reference LES. The statistics in the LPS are very robust to the number of the particles used in the simulations and the computational grid size of the LES. Both in the turbulent core region and the intermittent region, the LPS predicts a scalar field well correlated to the LES.« less

Thermodynamic properties of α-uranium

NASA Astrophysics Data System (ADS)

Ren, Zhiyong; Wu, Jun; Ma, Rong; Hu, Guichao; Luo, Chao

2016-11-01

The lattice constants and equilibrium atomic volume of α-uranium were calculated by Density Functional Theory (DFT). The first principles calculation results of the lattice for α-uranium are in agreement with the experimental results well. The thermodynamic properties of α-uranium from 0 to 900 K and 0-100 GPa were calculated with the quasi-harmonic Debye model. Volume, bulk modulus, entropy, Debye temperature, thermal expansion coefficient and the heat capacity of α-uranium were calculated. The calculated results show that the bulk modulus and Debye temperature increase with the increasing pressure at a given temperature while decreasing with the increasing temperature at a given pressure. Volume, entropy, thermal expansion coefficient and the heat capacity decrease with the increasing pressure while increasing with the increasing temperature. The theoretical results of entropy, Debye temperature, thermal expansion coefficient and the heat capacity show good agreement with the general trends of the experimental values. The constant-volume heat capacity shows typical Debye T3 power-law behavior at low temperature limit and approaches to the classical asymptotic Dulong-Petit limit at high temperature limit.

[Pulmonary function in patients with focal pulmonary tuberculosis].

PubMed

Nefedov, V B; Popova, L A; Shergina, E A

2008-01-01

Vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/VC%, PEF, MEF25, MEF50, MEF75, TLC, TGV, pulmonary residual volume (PRV), Raw, Rin, Rcx, DLCO-SB, DLCO-SS/VA, PaO2, and PaCO2 were determined in 40 patients with focal pulmonary tuberculosis. Changes were found in lung volumes and capacities in 75%, impaired bronchial patency and pulmonary gas exchange dysfunction were in 57.5 and 25%, respectively. The lung volume and capacity changes appeared mainly as increased TGV and PRV; impaired bronchial patency presented as decreased MEF50, MEF75, and FEV1/VC%; pulmonary gas exchange dysfunction manifested itself as reduced DLCO-SB, PaO2, and PaCO2. The magnitude of the observed functional changes was generally slight. TGV and PRL increased up to 148-187 and 142-223% of the normal values, respectively; MEF50, MEF75, FEV1/VC%, and DLCO decreased to 59-24, 58-26, 78-57, and 78-67% of the normal values and PaO2 and PaCO2 did to 79-69 and 34-30 cm Hg.

[Pulmonary function in patients with infiltrative pulmonary tuberculosis].

PubMed

Nefedov, V B; Popova, L A; Shergina, E A

2007-01-01

Vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/VC%, PEF, MEF25, MEF50, MEF75, TLC, TGV, pulmonary residual volume (PRV), R(aw), R(in),, R(ex), DLCO-SB, DLCO-SS, PaO2, and PaCO2 were determined in 103 patients with infiltrative pulmonary tuberculosis. Pulmonary dysfunction was detected in 83.5% of the patients. Changes were found in lung volumes and capacities in 63.1%, impaired bronchial patency and pulmonary gas exchange dysfunction were in 60.2 and 41.7%, respectively. The changes in pulmonary volumes and capacities appeared as increased PRV, decreased VC and FVC, and decreased and increased TGV and TLC; impaired bronchial patency presented as decreased PEF, MEF25, MEF50, MEF75, FEV1/VC% and increased R(aw) R(in), and R(ex); pulmonary gas exchange dysfunction manifested itself as reduced DLCO-SB, DLCO-SS, and PaO2 and decreased and increased PaCO2. The magnitude of the observed functional changes was generally slight. Significant disorders were observed rarely and very pronounced ones were exceptional.

[Pulmonary function in patients with disseminated pulmonary tuberculosis].

PubMed

Nefedov, V B; Shergina, E A; Popova, L A

2007-01-01

Vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/VC%, PEF, MEF25%, MEF50%, MEF75%, TLS, TGV, pulmonary residual volume (PRV), Raw, Rin, Rex, DLCO-SB, DLCO-SS, PaO2, and PaCO2 were determined in 29 patients with disseminated pulmonary tuberculosis. Pulmonary dysfunction was detected in 93.1% of the patients. Changes were found in lung volumes and capacities in 65.5%, impaired bronchial patency and pulmonary gas exchange dysfunction were in 79.3 and 37.9%, respectively. The changes in pulmonary volumes and capacities appeared as increased PRV, decreased VC, FVC, and TLS, decreased and increased TGV; impaired bronchial patency presented as decreased PEF, MEF25%, MEF50%, MEF75%, and FEV1/VC% and increased Raw, Rin, and Rex; pulmonary gas exchange dysfunction manifested itself as reduced DLCO-SS and PaO2 and decreased and increased PaCO2. The observed functional changes varied from slight to significant and pronounced with a preponderance of small disorders, a lower detection rate of significant disorders, and rare detection of very pronounced ones.

Structural and water diffusion of poly(acryl amide)/poly(vinyl alcohol) blend films: Experiment and molecular dynamics simulations.

PubMed

Wang, Yanen; Wei, Qinghua; Wang, Shuzhi; Chai, Weihong; Zhang, Yingfeng

2017-01-01

To study the effects of composition ratios and temperature on the diffusion of water molecules in PVA/PAM blend films, five simulation models of PVA/PAM with ten water molecules at different composition ratios (4/0, 3/1, 2/2, 1/3, 0/4) were constructed and simulated by using a molecular dynamics (MD) simulation. The diffusion behavior of water molecules in blends were investigated from the aspects of the diffusion coefficient, free volume, pair correlation function (PCF) and trajectories of water molecules, respectively. And the hydrophilicity of blend composite was studied based on the contact angle and equilibrium water content (EWC) of the blend films. The simulation results show that the diffusion coefficient of water molecules and fractional free volume (FFV) of blend membranes increase with the addition of PAM, and a higher temperature can also improve the diffusion of water molecules. Additionally, the analysis of PCFs reveals the main reason why the diffusion coefficient of water in blend system increases with the addition of PAM. The measurement results of contact angle and EWC of blend films indicate that the hydrophilicity of blend films decreases with the addition of PAM, but the EWC of blends increases with the addition of PAM. Copyright © 2016 Elsevier Inc. All rights reserved.

Delineation of discharge areas of two contaminant plumes by use of diffusion samplers, Johns Pond, Cape Cod, Massachusetts, 1998

USGS Publications Warehouse

Savoie, Jennifer G.; LeBlanc, D.R.; Blackwood, D.S.; McCobb, T.D.; Rendigs, R. R.; Clifford, Scott

2000-01-01

Diffusion samplers were installed in the bottom of Johns Pond, Cape Cod, Massachusetts, to confirm that volatile organic compounds from the Storm Drain-5 (SD-5) plume emanating from the Massachusetts Military Reservation (MMR) were discharging into the pond. An array of 134 vapor-diffusion samplers was buried by divers about 0.5 feet below the pond bottom in the presumed discharge area of the SD-5 plume and left in place for about 2 weeks to equilibrate. Two areas of high concentrations of volatile organic compounds (VOCs) were identified. Samples from the first area contained trichloroethene (TCE) and tetrachloroethene with concentrations in vapor as high as 890 and 667 parts per billion by volume, respectively. This discharge area is about 1,000 feet wide, extends from 100 to 350 feet offshore, and is interpreted to be the discharge area of the SD-5 plume. Samples from the second area were located closer to shore than the discharge area of the SD-5 plume and contained unexpectedly high vapor concentrations of TCE (more than 40,000 parts per billion by volume). Ground-water samples collected with a drive-point sampler near the second area had aqueous TCE concentrations as high as 1,100 micrograms per liter. Subsequently, a more closely spaced array of 110 vapor-diffusion samplers was installed to map the area of elevated TCE concentrations . The discharge area detected with the samplers is about 75 feet wide and extends from about 25 to 200 feet offshore . TCE vapor concentrations in this area were as high as 42,800 parts per billion by volume. TCE concentrations in micrograms per liter in water-diffusion samples from 15 selected sites in the two discharge areas were about 35 times lower than the TCE concentrations in parts per billion by volume in corresponding vapor-diffusion samples. The difference in values is due to the volatile nature of TCE and the different units of measure. TCE was detected in diffusion samplers set in the pond water column above the plume discharge areas, but the TCE concentrations were 20 to 30 times lower than the corresponding levels in diffusion samplers buried in the pond bottom.

Synthesis and characterization of nanostructured electrodes for solid state ionic devices

NASA Astrophysics Data System (ADS)

Zhang, Yuelan

Solid-state electrochemical energy conversion and storage technologies such as fuel cells and lithium ion batteries will influence the way we use energy and the environment we live in. The demands for advanced power sources with high energy efficiency, minimum environmental impact, and low cost have been the impetus for the development of a new generation of batteries and fuel cells. Currently, lithium ion battery technology's greatest disadvantages are long-term cycling stability and high charge/discharge rate capabilities. On the other hand, fuel cell technology's greatest disadvantage is cost. It is found that these problems could be attenuated by the incorporation of nano-structured materials. But, we are still far away from possessing a solid scientific understanding of what goes on at the nanoscale inside these solid state ionic devices, and what is the relationship between nano-structures and their electrochemical properties, especially between the microstructure and electrode polarization and degradation. Electrode polarization represents a voltage loss in an electrochemical energy conversion process. Such understanding is critical for further progress in solid state ionic devices. This thesis focused on the design, fabrication, and characterization of nanostructured porous electrodes with desired composition and microstructure to minimize electrode polarization losses in the application of fuel cells and lithium ion batteries. Various chemical methods such as sol-gel, hydrothermal, surfactant, colloidal and polymer template-assisted processes have been applied in this work. And various characterization techniques have been used to explore the understanding of the microscopic features with electrochemical interfacial properties of the electrodes. Solid-state diffusion often limits the utilization and rate capability of electrode materials in a lithium-ion battery, especially at high charge/discharge rates. When the fluxes of Li+ insertion or extraction exceeds the diffusion-limited rate of Li+ transport within the bulk phase of an electrode, concentration polarization occurs. Further, large volume changes associated with Li+ insertion or extraction could induce stresses in bulk electrodes, potentially leading to mechanical failure. Porous electrodes with high surface-to-volume ratio would increase the electrochemical reaction surface and suppress the mechanical stress. But porous electrodes also increase the tortuosity of mass transport within solid electrodes. Interconnected porous materials would decrease the percolation threshold for porous electrodes. In this work, electrodes with unique architecture for lithium ion batteries have been fabricated to improve the cycleability, rate capability and capacity retention. Spinel LiMn2O4 with interconnected macropores was created using a glycine-nitrate combustion process. Both microstructure and phase crystallinity were optimized by adjusting the fuel/oxidant ratio. This macroporous LiMn2O4 positive electrode exhibited better capacity retention and rate capability than those with larger particle size prepared by solid state reaction. Detailed electrode kinetic studies indicated that the macroporous microstructure promoted lithium diffusion and the overall reaction process was not controlled by lithium diffusion. Nanostructured tin oxide thin films with columnar grains less than 20 nm were deposited on Au/Si substrate using a combustion CVD method. The microstructure was highly porous and open, and thus was easily accessible to liquid electrolyte. In addition, the microstructure with vertical and radial connectivity of active materials led to decreased tortuosity for mass transport within solid electrodes. Nanoparticles accommodated the large volume change during cycling. These thin film electrodes exhibited highly reversible specific capacity and good capacity retention. It is about 93% after 80 cycles at a charge/discharge rate of 0.3 mA/cm2. When discharged at 0.9 mA/cm2, the obtained capacity retention was about 64% of the capacity at 0.3 mA/cm2. Cathodic interfacial polarization represents the predominant loss in a low-temperature SOFC. In this thesis, several porous nanocomposite electrodes of mixed ionic and electronic conductors (MIEC) with high surface areas were designed and fabricated to improve to minimize the polarization resistance. For the first time, regular, homogeneous and dual porous MIEC electrodes were successfully fabricated using breath figure templating, which is self-assembly of the water droplets in polymer solution. The homogeneous macropores promoted rapid mass transport by decreasing the tortuosity. Further, mesoporous microstructure provided more surface areas for gas adsorption and more TPBs for the electrochemical reactions. The interfacial polarization resistances were 0.94 and 0.39 Ocm 2 at 700 and 750°C, respectively. Furthermore, electrodes consisting of strontium doped lanthanum manganite (LSM) and gadolinium doped ceria (GDC) were developed with a modified sol-gel process for honeycomb SOFCs based on stabilized zirconia electrolytes. The sol gel derived cathodes with fine grain size and large specific surface area, showed much lower interfacial polarization resistances than those prepared by other processing methods. And this process developed strong bonding between the electrode and electrolyte even at low temperatures. The interfacial polarization resistances were 0.65 and 0.16 Ocm 2 at 650 and 750°C, respectively. The mesoscopic regime of overlapping space charge effects had a positive effect on the electrode kinetics. Ceria is a very important catalytic material for fuel reforming in SOFCs and CO poisoning in PEM fuel cells. Especially, the design of a new generation SOFC requires the in-situ reforming of hydrocarbon fuels. In this work, nanostructured ceria was developed via a controlled hydrothermal process in a mixed water-ethanol medium. The microstructure, formation mechanism, and their surface catalytic properties were investigated.

A reaction-diffusion model for market fluctuations - A relation between price change and traded volumes

NASA Astrophysics Data System (ADS)

Yuvan, Steven; Bier, Martin

2018-02-01

Two decades ago Bak et al. (1997) [3] proposed a reaction-diffusion model to describe market fluctuations. In the model buyers and sellers diffuse from opposite ends of a 1D interval that represents a price range. Trades occur when buyers and sellers meet. We show analytically and numerically that the model well reproduces the square-root relation between traded volumes and price changes that is observed in real-life markets. The result is remarkable as this relation has commonly been explained in terms of more elaborate trader strategies. We furthermore explain why the square-root relation is robust under model modifications and we show how real-life bond market data exhibit the square-root relation.

The quantitative impact of the mesopore size on the mass transfer mechanism of the new 1.9μm fully porous Titan-C18 particles. I: analysis of small molecules.

PubMed

Gritti, Fabrice; Guiochon, Georges

2015-03-06

Previous data have shown that could deliver a minimum reduced plate height as small as 1.7. Additionally, the reduction of the mesopore size after C18 derivatization and the subsequent restriction for sample diffusivity across the Titan-C18 particles were found responsible for the unusually small value of the experimental optimum reduced velocity (5 versus 10 for conventional particles) and for the large values of the average reduced solid-liquid mass transfer resistance coefficients (0.032 versus 0.016) measured for a series of seven n-alkanophenones. The improvements in column efficiency made by increasing the average mesopore size of the Titan silica from 80 to 120Å are investigated from a quantitative viewpoint based on the accurate measurements of the reduced coefficients (longitudinal diffusion, trans-particle mass transfer resistance, and eddy diffusion) and of the intra-particle diffusivity, pore, and surface diffusion for the same series of n-alkanophenone compounds. The experimental results reveal an increase (from 0% to 30%) of the longitudinal diffusion coefficients for the same sample concentration distribution (from 0.25 to 4) between the particle volume and the external volume of the column, a 40% increase of the intra-particle diffusivity for the same sample distribution (from 1 to 7) between the particle skeleton volume and the bulk phase, and a 15-30% decrease of the solid-liquid mass transfer coefficient for the n-alkanophenone compounds. Pore and surface diffusion are increased by 60% and 20%, respectively. The eddy dispersion term and the maximum column efficiency (295000plates/m) remain virtually unchanged. The rate of increase of the total plate height with increasing the chromatographic speed is reduced by 20% and it is mostly controlled (75% and 70% for 80 and 120Å pore size) by the flow rate dependence of the eddy dispersion term. Copyright © 2015 Elsevier B.V. All rights reserved.

Requirement of spatiotemporal resolution for imaging intracellular temperature distribution

NASA Astrophysics Data System (ADS)

Hiroi, Noriko; Tanimoto, Ryuichi; , Kaito, Ii; Ozeki, Mitsunori; Mashimo, Kota; Funahashi, Akira

2017-04-01

Intracellular temperature distribution is an emerging target in biology nowadays. Because thermal diffusion is rapid dynamics in comparison with molecular diffusion, we need a spatiotemporally high-resolution imaging technology to catch this phenomenon. We demonstrate that time-lapse imaging which consists of single-shot 3D volume images acquired at high-speed camera rate is desired for the imaging of intracellular thermal diffusion based on the simulation results of thermal diffusion from a nucleus to cytosol.

Ninteenth International Cosmic Ray Conference. OG Sessions, Volume 1

NASA Technical Reports Server (NTRS)

Jones, F. C. (Compiler)

1985-01-01

Contributed papers addressing cosmic ray origin and galactic phenomena are compiled. The topic areas covered in this volume include gamma ray bursts, gamma rays from point sources, and diffuse gamma ray emission.

Apparent diffusion coefficient of hyperpolarized (3)He with minimal influence of the residual gas in small animals.

PubMed

Carrero-González, L; Kaulisch, T; Ruiz-Cabello, J; Pérez-Sánchez, J M; Peces-Barba, G; Stiller, D; Rodríguez, I

2012-09-01

The apparent diffusion coefficient (ADC) of hyperpolarized (HP) gases is a parameter that reflects changes in lung microstructure. However, ADC is dependent on many physiological and experimental variables that need to be controlled or specified in order to ensure the reliability and reproducibility of this parameter. A single breath-hold experiment is desirable in order to reduce the amount of consumed HP gas. The application of a positive end-expiratory pressure (PEEP) causes an increase in the residual gas volume. Depending on the applied PEEP, the ratio between the incoming and residual gas volumes will change and the ADC will vary, as long as both gases do not have the same diffusion coefficient. The most standard method for human applications uses air for breathing and a bolus of pure HP (3)He for MRI data acquisition. By applying this method in rats, we have demonstrated that ADC values are strongly dependent on the applied PEEP, and therefore on the residual gas volume in the lung. This outcome will play an important role in studies concerning certain diseases, such as emphysema, which is characterized by an increase in the residual volume. Ventilation with an oxygen-helium mixture (VOHeM) is a proposed single breath-hold method that uses two different gas mixtures (O(2)-(4)He for ventilation and HP (3)He-N(2) for imaging). The concentration of each gas in its respective mixture was calculated in order to obtain the same diffusion coefficient in both mixtures. ADCs obtained from VOHeM are independent of PEEP, thus minimizing the effect of the different residual volumes. Copyright © 2012 John Wiley & Sons, Ltd.

Bistability: Requirements on Cell-Volume, Protein Diffusion, and Thermodynamics

PubMed Central

Endres, Robert G.

2015-01-01

Bistability is considered wide-spread among bacteria and eukaryotic cells, useful e.g. for enzyme induction, bet hedging, and epigenetic switching. However, this phenomenon has mostly been described with deterministic dynamic or well-mixed stochastic models. Here, we map known biological bistable systems onto the well-characterized biochemical Schlögl model, using analytical calculations and stochastic spatiotemporal simulations. In addition to network architecture and strong thermodynamic driving away from equilibrium, we show that bistability requires fine-tuning towards small cell volumes (or compartments) and fast protein diffusion (well mixing). Bistability is thus fragile and hence may be restricted to small bacteria and eukaryotic nuclei, with switching triggered by volume changes during the cell cycle. For large volumes, single cells generally loose their ability for bistable switching and instead undergo a first-order phase transition. PMID:25874711

A finite volume method for trace element diffusion and partitioning during crystal growth

NASA Astrophysics Data System (ADS)

Hesse, Marc A.

2012-09-01

A finite volume method on a uniform grid is presented to compute the polythermal diffusion and partitioning of a trace element during the growth of a porphyroblast crystal in a uniform matrix and in linear, cylindrical and spherical geometry. The motion of the crystal-matrix interface and the thermal evolution are prescribed functions of time. The motion of the interface is discretized and it advances from one cell boundary to next as the prescribed interface position passes the cell center. The appropriate conditions for the flux across the crystal-matrix interface are derived from discrete mass conservation. Numerical results are benchmarked against steady and transient analytic solutions for isothermal diffusion with partitioning and growth. Two applications illustrate the ability of the model to reproduce observed rare-earth element patterns in garnets (Skora et al., 2006) and water concentration profiles around spherulites in obsidian (Watkins et al., 2009). Simulations with diffusion inside the growing crystal show complex concentration evolutions for trace elements with high diffusion coefficients, such as argon or hydrogen, but demonstrate that rare-earth element concentrations in typical metamorphic garnets are not affected by intracrystalline diffusion.

Multinational Activities of Major U.S. Automotive Producers : Volume 5. Diffusion of Production and Sales Operations Abroad.

DOT National Transportation Integrated Search

1978-09-01

This is Volume V on the multi-national activities of the major U.S. automotive producers. The purpose of this Volume is to evaluate the foreign manufacturing and sales activities of the General Motors Corporation, Ford Motor Company, and Chrysler Cor...

Evaluation of Lung Function in Liver Transplant Candidates.

PubMed

Roque, L; Sankarankutty, A K; Silva, O C; Mente, E D

2018-04-01

A wide variety of pulmonary conditions are found in cirrhotic patients and may compromise the pleura, diaphragm, parenchyma, and pulmonary vasculature, influencing the results of liver transplantation. To evaluate the pulmonary function (lung capacities, volumes, and gasometric study) of patients with liver cirrhosis awaiting liver transplantation. Cirrhotic patients, subdivided into 3 groups stratified by liver disease severity using the Child-Pugh-Turcotte score, were compared with a control group of healthy volunteers. In spirometry, the parameters evaluated were total lung capacity, forced volume in the first second, and the relationship between forced volume in the first minute and forced vital capacity. Blood gas analysis was performed. In the control group, arterial oxygenation was evaluated by peripheral oxygen saturation by pulse oximetry. Of the 55 patients (75% men, 51 ± 12.77 years), 11 were Child A (73% men, 52 ± 14.01 years), 23 were Child B (75% men, 51 ± 12.77 years), and 21 were Child C (95% men, 50 ± 12.09 years). The control group had 20 individuals (50% men, 47 ± 8.15 years). Pulmonary capacities and volumes by the parameters evaluated were within the normal range. Arterial blood gas analysis detected no hypoxemia, but a tendency to low partial gas pressure was noted. In this population of cirrhotic patients the parameters of spirometry were normal in relation to the lung capacities and volumes in the different groups. No hypoxemia was detected, but a tendency to hypocapnia in the blood gas was noted. Copyright © 2018. Published by Elsevier Inc.

Short-duration transcutaneous electrical nerve stimulation in the postoperative period of cardiac surgery.

PubMed

Gregorini, Cristie; Cipriano Junior, Gerson; Aquino, Leticia Moraes de; Branco, João Nelson Rodrigues; Bernardelli, Graziella França

2010-03-01

Respiratory muscle strength has been related to the postoperative outcome of cardiac surgeries. The main documented therapeutic purpose of transcutaneous electrical nerve stimulation (TENS) is the reduction of pain, which could bring secondary benefits to the respiratory muscles and, consequently, to lung capacities and volumes. The objective of the present study was to evaluate the effectiveness of short-duration transcutaneous electrical nerve stimulation (TENS) in the reduction of pain and its possible influence on respiratory muscle strength and lung capacity and volumes of patients in the postoperative period of cardiac surgery. Twenty five patients with mean age of 59.9 +/- 10.3 years, of whom 72% were men, and homogeneous as regards weight and height, were randomly assigned to two groups. One group received therapeutic TENS (n = 13) and the other, placebo TENS (n = 12), for four hours on the third postoperative day of cardiac surgery. Pain was analyzed by means of a visual analogue scale, and of respiratory muscle strength as measured by maximum respiratory pressures and lung capacity and volumes before and after application of TENS. Short-duration TENS significantly reduced pain of patients in the postoperative period (p < 0.001). Respiratory muscle strength (p < 0.001), tidal volume (p < 0.001) and vital capacity (p < 0.05) significantly improved after therapeutic TENS, unlike in the placebo group. Short-duration TENS proved effective for the reduction of pain and improvement of respiratory muscle strength, as well as of lung volumes and capacity.

Salmeterol improves fluid clearance from alveolar-capillary membrane in COPD patients: a pilot study.

PubMed

Di Marco, Fabiano; Guazzi, Marco; Sferrazza Papa, Giuseppe Francesco; Vicenzi, Marco; Santus, Pierachille; Busatto, Paolo; Piffer, Federico; Blasi, Francesco; Centanni, Stefano

2012-02-01

The cardiovascular component associated with chronic obstructive pulmonary disease (COPD) plays a major role in disease prognosis, accounting for 25% of the deaths. Experimental and initial clinical data suggest that beta-adrenergic agonists accelerate fluid clearance from the alveolar airspace, with potentially positive effects on cardiogenic and noncardiogenic pulmonary oedema. This pilot study investigated the acute effects of the long-acting beta-2 agonist, salmeterol, on alveolar fluid clearance after rapid saline intravenous infusion by evaluating diffusive and mechanical lung properties. Ten COPD and 10 healthy subjects were treated with salmeterol or placebo 4 h before the patient's mechanical and diffusive lung properties were measured during four non consecutive days, just before and after a rapid saline infusion, or during a similar period without an infusion. In both COPD and healthy subjects, rapid saline infusion with placebo or salmeterol premedication lead to a significant decrease in diffusion capacity for carbon monoxide (DLCO) and forced expiratory volume in 1 s (FEV1). Nonetheless, salmeterol pretreatment lead to a significantly reduced gas exchange impairment caused by saline infusion (-64% of DLCO reduction compared with placebo), whereas it did not affect changes in FEV1. In the control setting with no infusion, we found no significant change in either DLCO or mechanical properties of the lung. Salmeterol appears to provide a protective effect, not related to bronchodilation, against an acute alveolar fluid clearance challenge secondary to lung fluid overload in COPD patients. Copyright © 2012 Elsevier Ltd. All rights reserved.

Potential of wind power projects under the Clean Development Mechanism in India

PubMed Central

Purohit, Pallav; Michaelowa, Axel

2007-01-01

Background So far, the cumulative installed capacity of wind power projects in India is far below their gross potential (≤ 15%) despite very high level of policy support, tax benefits, long term financing schemes etc., for more than 10 years etc. One of the major barriers is the high costs of investments in these systems. The Clean Development Mechanism (CDM) of the Kyoto Protocol provides industrialized countries with an incentive to invest in emission reduction projects in developing countries to achieve a reduction in CO2 emissions at lowest cost that also promotes sustainable development in the host country. Wind power projects could be of interest under the CDM because they directly displace greenhouse gas emissions while contributing to sustainable rural development, if developed correctly. Results Our estimates indicate that there is a vast theoretical potential of CO2 mitigation by the use of wind energy in India. The annual potential Certified Emissions Reductions (CERs) of wind power projects in India could theoretically reach 86 million. Under more realistic assumptions about diffusion of wind power projects based on past experiences with the government-run programmes, annual CER volumes by 2012 could reach 41 to 67 million and 78 to 83 million by 2020. Conclusion The projections based on the past diffusion trend indicate that in India, even with highly favorable assumptions, the dissemination of wind power projects is not likely to reach its maximum estimated potential in another 15 years. CDM could help to achieve the maximum utilization potential more rapidly as compared to the current diffusion trend if supportive policies are introduced. PMID:17663772

Upscaling the diffusion equations in particulate media made of highly conductive particles. I. Theoretical aspects.

PubMed

Vassal, J-P; Orgéas, L; Favier, D; Auriault, J-L; Le Corre, S

2008-01-01

Many analytical and numerical works have been devoted to the prediction of macroscopic effective transport properties in particulate media. Usually, structure and properties of macroscopic balance and constitutive equations are stated a priori. In this paper, the upscaling of the transient diffusion equations in concentrated particulate media with possible particle-particle interfacial barriers, highly conductive particles, poorly conductive matrix, and temperature-dependent physical properties is revisited using the homogenization method based on multiple scale asymptotic expansions. This method uses no a priori assumptions on the physics at the macroscale. For the considered physics and microstructures and depending on the order of magnitude of dimensionless Biot and Fourier numbers, it is shown that some situations cannot be homogenized. For other situations, three different macroscopic models are identified, depending on the quality of particle-particle contacts. They are one-phase media, following the standard heat equation and Fourier's law. Calculations of the effective conductivity tensor and heat capacity are proved to be uncoupled. Linear and steady state continuous localization problems must be solved on representative elementary volumes to compute the effective conductivity tensors for the two first models. For the third model, i.e., for highly resistive contacts, the localization problem becomes simpler and discrete whatever the shape of particles. In paper II [Vassal, Phys. Rev. E 77, 011303 (2008)], diffusion through networks of slender, wavy, entangled, and oriented fibers is considered. Discrete localization problems can then be obtained for all models, as well as semianalytical or fully analytical expressions of the corresponding effective conductivity tensors.

Diffusion-Welded Microchannel Heat Exchanger for Industrial Processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Piyush Sabharwall; Denis E. Clark; Michael V. Glazoff

The goal of next generation reactors is to increase energy ef?ciency in the production of electricity and provide high-temperature heat for industrial processes. The ef?cient transfer of energy for industrial applications depends on the ability to incorporate effective heat exchangers between the nuclear heat transport system and the industrial process. The need for ef?ciency, compactness, and safety challenge the boundaries of existing heat exchanger technology. Various studies have been performed in attempts to update the secondary heat exchanger that is downstream of the primary heat exchanger, mostly because its performance is strongly tied to the ability to employ more ef?cientmore » industrial processes. Modern compact heat exchangers can provide high compactness, a measure of the ratio of surface area-to-volume of a heat exchange. The microchannel heat exchanger studied here is a plate-type, robust heat exchanger that combines compactness, low pressure drop, high effectiveness, and the ability to operate with a very large pressure differential between hot and cold sides. The plates are etched and thereafter joined by diffusion welding, resulting in extremely strong all-metal heat exchanger cores. After bonding, any number of core blocks can be welded together to provide the required ?ow capacity. This study explores the microchannel heat exchanger and draws conclusions about diffusion welding/bonding for joining heat exchanger plates, with both experimental and computational modeling, along with existing challenges and gaps. Also, presented is a thermal design method for determining overall design speci?cations for a microchannel printed circuit heat exchanger for both supercritical (24 MPa) and subcritical (17 MPa) Rankine power cycles.« less

Correlation of ultra-low dose chest CT findings with physiologic measures of asbestosis.

PubMed

Manners, David; Wong, Patrick; Murray, Conor; Teh, Joelin; Kwok, Yi Jin; de Klerk, Nick; Alfonso, Helman; Franklin, Peter; Reid, Alison; Musk, A W Bill; Brims, Fraser J H

2017-08-01

The correlation between ultra low dose computed tomography (ULDCT)-detected parenchymal lung changes and pulmonary function abnormalities is not well described. This study aimed to determine the relationship between ULDCT-detected interstitial lung disease (ILD) and measures of pulmonary function in an asbestos-exposed population. Two thoracic radiologists independently categorised prone ULDCT scans from 143 participants for ILD appearances as absent (score 0), probable (1) or definite (2) without knowledge of asbestos exposure or lung function. Pulmonary function measures included spirometry and diffusing capacity to carbon monoxide (DLCO). Participants were 92% male with a median age of 73.0 years. CT dose index volume was between 0.6 and 1.8 mGy. Probable or definite ILD was reported in 63 (44.1%) participants. Inter-observer agreement was good (k = 0.613, p < 0.001). There was a statistically significant correlation between the ILD score and both forced expiratory volume in 1 second (FEV 1 ) and forced vital capacity (FVC) (r = -0.17, p = 0.04 and r = -0.20, p = 0.02). There was a strong correlation between ILD score and DLCO (r = -0.34, p < 0.0001). Changes consistent with ILD on ULDCT correlate well with corresponding reductions in gas transfer, similar to standard CT. In asbestos-exposed populations, ULDCT may be adequate to detect radiological changes consistent with asbestosis. • Interobserver agreement for the ILD score using prone ULDCT is good. • Prone ULDCT appearances of ILD correlate with changes in spirometric observations. • Prone ULDCT appearances of ILD correlate strongly with changes in gas transfer. • Prone ULDCT may provide sufficient radiological evidence to inform the diagnosis of asbestosis.

Respiratory physiotherapy in the pre and postoperative myocardial revascularization surgery.

PubMed

Cavenaghi, Simone; Ferreira, Lucas Lima; Marino, Lais Helena Carvalho; Lamari, Neuseli Marino

2011-01-01

The cardiovascular diseases are among the main death causes in the developed world. They have been increasing epidemically in the developing countries. In spite of several alternatives for the treatment of the coronary artery disease; the surgery of the myocardial revascularization is an option with proper indications of medium and long-term with good results. It provides the remission of the angina symptoms contributing to the increase of the expectation and improvement of the life quality. Most of patients undergoing myocardial revascularization surgery develop postoperative lung dysfunction with important reduction of the lung volumes, damages in the respiratory mechanism, decrease in the lung indulgence and increase of the respiratory work. The reduction of volumes and lung capacities can contribute to alterations in the gas exchanges, resulting in hypoxemia and decrease in the diffusion capacity. Taking this into account, the Physiotherapy has been requested more and more to perform in the pre as well as in the postoperative period of this surgery. This study aimed at updating the knowledge regarding the respiratory physiotherapy performance in the pre and postoperative period of the myocardial revascularization surgery enhancing the prevention of lung complications. The Physiotherapy uses several techniques in the preoperative period; such as: the incentive spirometry, exercises of deep breathing, cough, inspiratory muscle training, earlier ambulation and physiotherapeutic orientations. While in the postoperative period, the objective is the treatment after lung complications took place, performed by means of physiotherapeutic maneuvers and noninvasive respiratory devices, aiming at improving the respiratory mechanism, the lung reexpansion and the bronchial hygiene. Respiratory physiotherapy is an integral part in the care management of the patient with cardiopathy, either in the pre or in the postoperative period, since it contributes significantly to a better prognosis of these patients with the use of specific techniques.

Preparation of a Si/SiO2 -Ordered-Mesoporous-Carbon Nanocomposite as an Anode for High-Performance Lithium-Ion and Sodium-Ion Batteries.

PubMed

Zeng, Lingxing; Liu, Renpin; Han, Lei; Luo, Fenqiang; Chen, Xi; Wang, Jianbiao; Qian, Qingrong; Chen, Qinghua; Wei, Mingdeng

2018-04-03

In this work, an Si/SiO 2 -ordered-mesoporous carbon (Si/SiO 2 -OMC) nanocomposite was initially fabricated through a magnesiothermic reduction strategy by using a two-dimensional bicontinuous mesochannel of SiO 2 -OMC as a precursor, combined with an NaOH etching process, in which crystal Si/amorphous SiO 2 nanoparticles were encapsulated into the OMC matrix. Not only can such unique porous crystal Si/amorphous SiO 2 nanoparticles uniformly dispersed in the OMC matrix mitigate the volume change of active materials during the cycling process, but they can also improve electrical conductivity of Si/SiO 2 and facilitate the Li + /Na + diffusion. When applied as an anode for lithium-ion batteries (LIBs), the Si/SiO 2 -OMC composite displayed superior reversible capacity (958 mA h g -1 at 0.2 A g -1 after 100 cycles) and good cycling life (retaining a capacity of 459 mA h g -1 at 2 A g -1 after 1000 cycles). For sodium-ion batteries (SIBs), the composite maintained a high capacity of 423 mA h g -1 after 100 cycles at 0.05 A g -1 and an extremely stable reversible capacity of 190 mA h g -1 was retained even after 500 cycles at 1 A g -1 . This performance is one of the best long-term cycling properties of Si-based SIB anode materials. The Si/SiO 2 -OMC composites exhibited great potential as an alternative material for both lithium- and sodium-ion battery anodes. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reaping the redox switching capability of vanadium in Li3V2(PO4)3/HHC composite to demonstrate the rocking chair electrode performance

NASA Astrophysics Data System (ADS)

Saravanan, Karuppiah; Kalaiselvi, Nallathamby

2017-10-01

The study exploits the functional advantages of vanadium with variable oxidation states to extract maximum energy from Li3V2(PO4)3/HHC composite containing human hair derived carbon. Vanadium, present in the form of V3+ in Li3V2(PO4)3 stabilizes itself electrochemically as V4+ by forming LiV2(PO4)3 through oxidation in the potential range 3.0-4.5 V and as V1+ by forming Li7V2(PO4)3 due to the reduction of V3+ into V1+ in the 0.01-3.0 V region, thus qualifying LVP as a rocking chair electrode. In other words, Li3V2(PO4)3/HHC composite demonstrates itself as anode and as cathode for lithium-ion batteries. Li3V2(PO4)3/HHC cathode exhibits ultra high capacity, excellent rate capability at 50C and retains about 99% capacity up to 1000 cycles. As anode, Li3V2(PO4)3/HHC delivers a capacity of 428 mAh g-1 at 50 mA g-1 and tolerates 5 A g-1 condition up to 1000 cycles with a negligible capacity fade. The dual electrode behavior of Li3V2(PO4)3/HHC may be attributed to the unique architecture of HHC that provides high electronic conductivity, facilitates rapid diffusion of lithium ions and admits volume changes during intercalation/deintercalation. More importantly, HHC is a cheap and eco-friendly carbon additive derived from filthy human hair, which in turn offers ample scope for the commercial exploitation of title electrode.

The Environmental Protection Agency's brownfields pilot program.

PubMed

Greenberg, Michael R; Hollander, Justin

2006-02-01

We studied the diffusion of the US Environmental Protection Agency's national brownfields pilot innovation to more than 300 local governments between 1993 through 2002 to determine why some local governments received grants very early in the process while other awardees received funding later. We did an ordinal regression analysis of the characteristics of all local government award recipients, and we conducted interviews with early-award recipients. The first set of local government awardees had lost much of their manufacturing base, had large concentrations of economically disadvantaged minority residents, and had local capacity to compete for funding. Federal and state officials catalyzed the diffusion of the innovation by working with local governments. The widely praised program was diffused selectively at first and then more widely later on the basis of local need, local capacity to compete, and networks of contacts among entrepreneurs and local governments. The economic, social, political, and public health impacts must be monitored and reviewed.

Regional frontal gray matter volume associated with executive function capacity as a risk factor for vehicle crashes in normal aging adults.

PubMed

Sakai, Hiroyuki; Takahara, Miwa; Honjo, Naomi F; Doi, Shun'ichi; Sadato, Norihiro; Uchiyama, Yuji

2012-01-01

Although low executive functioning is a risk factor for vehicle crashes among elderly drivers, the neural basis of individual differences in this cognitive ability remains largely unknown. Here we aimed to examine regional frontal gray matter volume associated with executive functioning in normal aging individuals, using voxel-based morphometry (VBM). To this end, 39 community-dwelling elderly volunteers who drove a car on a daily basis participated in structural magnetic resonance imaging, and completed two questionnaires concerning executive functioning and risky driving tendencies in daily living. Consequently, we found that participants with low executive function capacity were prone to risky driving. Furthermore, VBM analysis revealed that lower executive function capacity was associated with smaller gray matter volume in the supplementary motor area (SMA). Thus, the current data suggest that SMA volume is a reliable predictor of individual differences in executive function capacity as a risk factor for vehicle crashes among elderly persons. The implication of our results is that regional frontal gray matter volume might underlie the variation in driving tendencies among elderly drivers. Therefore, detailed driving behavior assessments might be able to detect early neurodegenerative changes in the frontal lobe in normal aging adults.

A network model of successive partitioning-limited solute diffusion through the stratum corneum.

PubMed

Schumm, Phillip; Scoglio, Caterina M; van der Merwe, Deon

2010-02-07

As the most exposed point of contact with the external environment, the skin is an important barrier to many chemical exposures, including medications, potentially toxic chemicals and cosmetics. Traditional dermal absorption models treat the stratum corneum lipids as a homogenous medium through which solutes diffuse according to Fick's first law of diffusion. This approach does not explain non-linear absorption and irregular distribution patterns within the stratum corneum lipids as observed in experimental data. A network model, based on successive partitioning-limited solute diffusion through the stratum corneum, where the lipid structure is represented by a large, sparse, and regular network where nodes have variable characteristics, offers an alternative, efficient, and flexible approach to dermal absorption modeling that simulates non-linear absorption data patterns. Four model versions are presented: two linear models, which have unlimited node capacities, and two non-linear models, which have limited node capacities. The non-linear model outputs produce absorption to dose relationships that can be best characterized quantitatively by using power equations, similar to the equations used to describe non-linear experimental data.

Theoretical and experimental models of the diffuse radar backscatter from Mars

NASA Technical Reports Server (NTRS)

England, A. W.

1995-01-01

The general objective for this work was to develop a theoretically and experimentally consistent explanation for the diffuse component of radar backscatter from Mars. The strength, variability, and wavelength independence of Mars' diffuse backscatter are unique among our Moon and the terrestrial planets. This diffuse backscatter is generally attributed to wavelength-scale surface roughness and to rock clasts within the Martian regolith. Through the combination of theory and experiment, the authors attempted to bound the range of surface characteristics that could produce the observed diffuse backscatter. Through these bounds they gained a limited capability for data inversion. Within this umbrella, specific objectives were: (1) To better define the statistical roughness parameters of Mars' surface so that they are consistent with observed radar backscatter data, and with the physical and chemical characteristics of Mars' surface as inferred from Mariner 9, the Viking probes, and Earth-based spectroscopy; (2) To better understand the partitioning between surface and volume scattering in the Mars regolith; (3) To develop computational models of Mars' radio emission that incorporate frequency dependent, surface and volume scattering.

Fostering Scholarship Capacity: The Experience of Nurse Educators

ERIC Educational Resources Information Center

Cash, Penelope A.; Tate, Betty

2012-01-01

In a milieu where traditional views of scholarship are embedded in the culture of educational institutions, and nursing programs in particular, this paper reports on a research project designed to support nurse educators' capacity to engage in scholarly activities. Rogers' (2003, 2004) "Diffusion of Innovation" model provided a…

Spontaneous crystalline-to-amorphous phase transformation of organic or medicinal compounds in the presence of porous media, part 2: amorphization capacity and mechanisms of interaction.

PubMed

Qian, Ken K; Suib, Steven L; Bogner, Robin H

2011-11-01

Amorphization of crystalline compounds using mesoporous media is a promising technique to improve the solubility and dissolution rate of poorly soluble compounds. The objective of this paper is to determine the capacity of amorphization and understand the mechanisms of phase transformation. Commercial grades of mesoporous silicon dioxide (SiO(2)) samples (5- to 30-nm mean pore diameters) with either constant surface area or constant pore volume were used. The amorphization capacity of naphthalene was not proportional to either the surface area or the pore volume measured using adsorption chambers. Instead, the amorphization capacity correlated with surface curvature, that is, the smaller the pore diameter and the higher the surface curvature, the greater the amorphization capacity. The change in surface chemistry due to a highly curved surface may be responsible for the enhanced amorphization capacity as well. The amorphization of crystalline compounds was facilitated through capillary condensation, with the decrease in pore volume as the direct experimental evidence. The amorphization capacity was also enhanced by the dipole-dipole or dipole-induced dipole interaction, promoted by the hydroxyl groups on the surface of SiO(2). The enthalpy of vapor-solid condensation of crystalline compounds was a useful indicator to predict the rank order of amorphization capacity. Copyright © 2011 Wiley-Liss, Inc.

Scaling trace organic contaminant adsorption capacity by granular activated carbon.

PubMed

Corwin, Christopher J; Summers, R Scott

2010-07-15

The role of particle size on the reduction of granular activated carbon (GAC) adsorption capacity for trace organic contaminants by dissolved organic matter (DOM) is examined and applied to performance scale-up. The adsorption capacity reduction, termed fouling, must be scalable in order to use bench scale tests, such as the rapid small-scale column test (RSSCT) to predict full-scale breakthrough. Equilibrium adsorption capacity tests with GAC preloaded with DOM and RSSCT breakthrough curves at three different GAC particle sizes indicate that GAC adsorption capacity is dependent on GAC particle size when DOM is present. Thus, the RSSCT cannot be expected to match full-scale results regardless of which RSSCT design approach is used (constant or proportional diffusivity), unless a scaling factor is applied to the results. Proportional diffusivity RSSCT breakthrough curves demonstrate that surface concentration of DOM is not a good measure of fouling. It is hypothesized that pore blockage is the mechanism responsible for the dependence on particle size. As GAC particle size increases, the microporous surface area behind a constricted pore also increases. The result is lower adsorption capacity per mass of adsorbent in the larger GAC particles. A scaling methodology for equilibrium and breakthrough data is presented that accounts for the dependence of NOM preloading effects on GAC particle diameter.

Prospective longitudinal MRI study of brain volumes and diffusion changes during the first year after moderate to severe traumatic brain injury

PubMed Central

Brezova, Veronika; G⊘ran Moen, Kent; Skandsen, Toril; Vik, Anne; Brewer, James B.; Salvesen, Øyvind; Håberg, Asta K.

2014-01-01

The objectives of this prospective study in 62 moderate–severe TBI patients were to investigate volume change in cortical gray matter (GM), hippocampus, lenticular nucleus, lobar white matter (WM), brainstem and ventricles using a within subject design and repeated MRI in the early phase (1–26 days) and 3 and 12 months postinjury and to assess changes in GM apparent diffusion coefficient (ADC) in normal appearing tissue in the cortex, hippocampus and brainstem. The impact of Glasgow Coma Scale (GCS) score at admission, duration of post-traumatic amnesia (PTA), and diffusion axonal injury (DAI) grade on brain volumes and ADC values over time was assessed. Lastly, we determined if MRI-derived brain volumes from the 3-month scans provided additional, significant predictive value to 12-month outcome classified with the Glasgow Outcome Scale—Extended after adjusting for GCS, PTA and age. Cortical GM loss was rapid, largely finished by 3 months, but the volume reduction was unrelated to GCS score, PTA, or presence of DAI. However, cortical GM volume at 3 months was a significant independent predictor of 12-month outcome. Volume loss in the hippocampus and lenticular nucleus was protracted and statistically significant first at 12 months. Slopes of volume reduction over time for the cortical and subcortical GGM were significantly different. Hippocampal volume loss was most pronounced and rapid in individuals with PTA > 2 weeks. The 3-month volumes of the hippocampus and lentiform nucleus were the best independent predictors of 12-month outcome after adjusting for GCS, PTA and age. In the brainstem, volume loss was significant at both 3 and 12 months. Brainstem volume reduction was associated with lower GCS score and the presence of DAI. Lobar WM volume was significantly decreased first after 12 months. Surprisingly DAI grade had no impact on lobar WM volume. Ventricular dilation developed predominantly during the first 3 months, and was strongly associated with volume changes in the brainstem and cortical GM, but not lobar WM volume. Higher ADC values were detected in the cortex in individuals with severe TBI, DAI and PTA > 2 weeks, from 3 months. There were no associations between ADC values and brain volumes, and ADC values did not predict outcome. PMID:25068105

[Stereotactic lung radiotherapy: Technical setting up on Novalis Tx® and single centre prospective study of the 100 first malignant pulmonary nodules treated at centre Jean-Perrin].

PubMed

Bellière-Calandry, A; Dupic, G; Magnier, F; Chassin, V; Dedieu, V; Lapeyre, M

2017-06-01

Description of the treatment technique of stereotactic lung radiotherapy on Novalis Tx ® and prospective study of the first 100 pulmonary nodules treated at centre Jean-Perrin (France). From October 2012 to December 2015, 100 inoperable pulmonary nodules (62 stage I non-small-cell lung cancer and 38 metastases) of 90 patients with a mean age of 68.2 years (range: 46-89 years) were prospectively treated with dynamic arctherapy on Novalis Tx ® . Mean gross tumour and planning target volumes were respectively 6.9 cm 3 (range: 0.2-31.4 cm 3 ) and 38.7 cm 3 (range: 1.7-131 cm 3 ), which correspond to diameters equal to 2.3cm and 4.2cm. Prescribed doses to the 80% isodose line were 54Gy in three fractions for peripheral non-small-cell lung cancer, 50Gy in five fractions for central non-small-cell lung cancer and 45Gy in three fractions for lung metastases. Clinical and radiological follow-up was done every three months with RECIST criteria for efficacy and NCI-CTCAE v4 scale for toxicity. Median follow-up was 12.5 months. Complete response was observed in 23.8% of cases. Local control rates were 100% and 90.7% respectively at 12 and 24 months, with 96% at 24 months for stage I non-small-cell lung cancer. Overall survival rates of patients with stage I non-small-cell lung cancer were 77.4% and 73.5% at 12 and 24 months (median overall survival was 32 months). Diffusing capacity of the lungs for carbon monoxide corrected for alveolar volume below 40% was significantly associated to a poor prognostic factor on univariate analysis (P=0.00013). At least three deaths were due to an acute respiratory failure, which correspond to about 4.8% of grade 5 radiation pneumonitis. Overall survival rate for metastatic patients were 95.2% and 59.5% respectively at 12 and 24 months (median overall survival was 25 months); 23.3% of grade 2 or less radiation pneumonitis, 7.8% of grade 2 or less radiation dermatitis, 2.2% of asymptomatic ribs fracture and 3.3% of chest pains were observed. Stereotactic lung radiotherapy is an effective treatment for inoperable stage I non-small-cell lung cancer and lung oligometastases of well informed and selected patients. Initial respiratory state, and especially the diffusing capacity of the lungs for carbon monoxide corrected for alveolar volume, seems to be important for tolerance. Copyright © 2017 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

Capacity Initiatives, Volume 2

DOT National Transportation Integrated Search

1992-07-01

This is the second in a series of pamphlets detailing capacity initiatives that : offer solutions for improving the Nation's aviation system capacity. Based on : the application and refinement of new systems and procedures, these initiatives : promis...

Enhancement of crop photosynthesis by diffuse light: quantifying the contributing factors

PubMed Central

Li, T.; Heuvelink, E.; Dueck, T. A.; Janse, J.; Gort, G.; Marcelis, L. F. M.

2014-01-01

Background and Aims Plants use diffuse light more efficiently than direct light. However, experimental comparisons between diffuse and direct light have been obscured by co-occurring differences in environmental conditions (e.g. light intensity). This study aims to analyse the factors that contribute to an increase in crop photosynthesis in diffuse light and to quantify their relative contribution under different levels of diffuseness at similar light intensities. The hypothesis is that the enhancement of crop photosynthesis in diffuse light results not only from the direct effects of more uniform vertical and horizontal light distribution in the crop canopy, but also from crop physiological and morphological acclimation. Methods Tomato (Solanum lycopersicum) crops were grown in three greenhouse compartments that were covered by glass with different degrees of light diffuseness (0, 45 and 71 % of the direct light being converted into diffuse light) while maintaining similar light transmission. Measurements of horizontal and vertical photosynthetic photon flux density (PPFD) distribution in the crop, leaf photosynthesis light response curves and leaf area index (LAI) were used to quantify each factor's contribution to an increase in crop photosynthesis in diffuse light. In addition, leaf temperature, photoinhibition, and leaf biochemical and anatomical properties were studied. Key Results The highest degree of light diffuseness (71 %) increased the calculated crop photosynthesis by 7·2 %. This effect was mainly attributed to a more uniform horizontal (33 % of the total effect) and vertical PPFD distribution (21 %) in the crop. In addition, plants acclimated to the high level of diffuseness by gaining a higher photosynthetic capacity of leaves in the middle of the crop and a higher LAI, which contributed 23 and 13 %, respectively, to the total increase in crop photosynthesis in diffuse light. Moreover, diffuse light resulted in lower leaf temperatures and less photoinhibition at the top of the canopy when global irradiance was high. Conclusions Diffuse light enhanced crop photosynthesis. A more uniform horizontal PPFD distribution played the most important role in this enhancement, and a more uniform vertical PPFD distribution and higher leaf photosynthetic capacity contributed more to the enhancement of crop photosynthesis than did higher values of LAI. PMID:24782436

A theoretical model to determine the capacity performance of shape-specific electrodes

NASA Astrophysics Data System (ADS)

Yue, Yuan; Liang, Hong

2018-06-01

A theory is proposed to explain and predict the electrochemical process during reaction between lithium ions and electrode materials. In the model, the process of reaction is proceeded into two steps, surface adsorption and diffusion of lithium ions. The surface adsorption is an instantaneous process for lithium ions to adsorb onto the surface sites of active materials. The diffusion of lithium ions into particles is determined by the charge-discharge condition. A formula to determine the maximum specific capacity of active materials at different charging rates (C-rates) is derived. The maximum specific capacity is correlated to characteristic parameters of materials and cycling - such as size, aspect ratio, surface area, and C-rate. Analysis indicates that larger particle size or greater aspect ratio of active materials and faster C-rates can reduce maximum specific capacity. This suggests that reducing particle size of active materials and slowing the charge-discharge speed can provide enhanced electrochemical performance of a battery cell. Furthermore, the model is validated by published experimental results. This model brings new understanding in quantification of electrochemical kinetics and capacity performance. It enables development of design strategies for novel electrodes and future generation of energy storage devices.

SnS2 /Sb2 S3 Heterostructures Anchored on Reduced Graphene Oxide Nanosheets with Superior Rate Capability for Sodium-Ion Batteries.

PubMed

Wang, Shijian; Liu, Shuaishuai; Li, Xuemei; Li, Cong; Zang, Rui; Man, Zengming; Wu, Yuhan; Li, Pengxin; Wang, Guoxiu

2018-03-12

Tin disulfide, as a promising high-capacity anode material for sodium-ion batteries, exhibits high theoretical capacity but poor practical electrochemical properties due to its low electrical conductivity. Constructing heterostructures has been considered to be an effective approach to enhance charge transfer and ion-diffusion kinetics. In this work, composites of SnS 2 /Sb 2 S 3 heterostructures with reduced graphene oxide nanosheets were synthesized by a facile one-pot hydrothermal method. When applied as anode material in sodium-ion batteries, the composite showed a high reversible capacity of 642 mA h g -1 at a current density of 0.2 A g -1 and good cyclic stability without capacity loss in 100 cycles. In particular, SnS 2 /Sb 2 S 3 heterostructures exhibited outstanding rate performance with capacities of 593 and 567 mA h g -1 at high current densities of 2 and 4 A g -1 , respectively, which could be ascribed to the dramatically improved Na + diffusion kinetics and electrical conductivity. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cost and effectiveness of lung lobectomy by video-assisted thoracic surgery for lung cancer

PubMed Central

Mafé, Juan J.; Planelles, Beatriz; Asensio, Santos; Cerezal, Jorge; Inda, María-del-Mar; Lacueva, Javier; Esteban, Maria-Dolores; Hernández, Luis; Martín, Concepción; Baschwitz, Benno

2017-01-01

Background Video-assisted thoracic surgery (VATS) emerged as a minimally invasive surgery for diseases in the field of thoracic surgery. We herein reviewed our experience on thoracoscopic lobectomy for early lung cancer and evaluated Health System use. Methods A cost-effectiveness study was performed comparing VATS vs. open thoracic surgery (OPEN) for lung cancer patients. Demographic data, tumor localization, dynamic pulmonary function tests [forced vital capacity (FVC), forced expiratory volume in one second (FEV1), diffusion capacity (DLCO) and maximal oxygen uptake (VO2max)], surgical approach, postoperative details, and complications were recorded and analyzed. Results One hundred seventeen patients underwent lung resection by VATS (n=42, 36%; age: 63±9 years old, 57% males) or OPEN (n=75, 64%; age: 61±11 years old, 73% males). Pulmonary function tests decreased just after surgery with a parallel increasing tendency during first 12 months. VATS group tended to recover FEV1 and FVC quicker with significantly less clinical and post-surgical complications (31% vs. 53%, P=0.015). Costs including surgery and associated hospital stay, complications and costs in the 12 months after surgery were significantly lower for VATS (P<0.05). Conclusions The VATS approach surgery allowed earlier recovery at a lower cost than OPEN with a better cost-effectiveness profile. PMID:28932560

A nitrogen-doped 3D hierarchical carbon/sulfur composite for advanced lithium sulfur batteries

NASA Astrophysics Data System (ADS)

Liu, Xiaoyan; Huang, Wenlong; Wang, Dongdong; Tian, Jianhua; Shan, Zhongqiang

2017-07-01

Hybrid nanostructures containing one-dimensional (1D) carbon nanotubes (CNTs) and three-dimensional (3D) mesoporous carbon sphere have many promising applications due to their unique physical chemical properties. In this study, a novel 3D hierarchical carbon material (MCCNT) composed of mesoporous carbon sphere core and nitrogen rich CNTs shell is successfully prepared via an aerosol spray and subsequent chemical vapor deposition (CVD) processes. Owning to its well defined porous structure and favorable conductive framework, MCCNT is used as a potential sulfur host in lithium sulfur batteries through a classic melt-diffusion method. When cycled at a current density of 0.2 C (1 C = 1675 mA h g-1), it delivers an initial capacity as high as 1438.7 mAh g-1. Even if the current density increase to 1 C, the specific capacity still remain up to 534.6 mAh g-1 after 300 cycles. The enhanced electrochemical performance can be attributed to the hybrid structure of MCCNT, in which, the porous core works as a host to confine sulfur and accommodate volume expansion and the external CNTs provide excellent electron and ion conductive frame work. Furthermore, the in-situ doped nitrogen on the surface of CNTs enables effective trapping of lithium polysulfides, leading to a much-improved cycling performance.

Spherical Macroporous Carbon Nanotube Particles with Ultrahigh Sulfur Loading for Lithium-Sulfur Battery Cathodes.

PubMed

Gueon, Donghee; Hwang, Jeong Tae; Yang, Seung Bo; Cho, Eunkyung; Sohn, Kwonnam; Yang, Doo-Kyung; Moon, Jun Hyuk

2018-01-23

A carbon host capable of effective and uniform sulfur loading is the key for lithium-sulfur batteries (LSBs). Despite the application of porous carbon materials of various morphologies, the carbon hosts capable of uniformly impregnating highly active sulfur is still challenging. To address this issue, we demonstrate a hierarchical pore-structured CNT particle host containing spherical macropores of several hundred nanometers. The macropore CNT particles (M-CNTPs) are prepared by drying the aerosol droplets in which CNTs and polymer particles are dispersed. The spherical macropore greatly improves the penetration of sulfur into the carbon host in the melt diffusion of sulfur. In addition, the formation of macropores greatly develops the volume of the micropore between CNT strands. As a result, we uniformly impregnate 70 wt % sulfur without sulfur residue. The S-M-CNTP cathode shows a highly reversible capacity of 1343 mA h g -1 at a current density of 0.2 C even at a high sulfur content of 70 wt %. Upon a 10-fold current density increase, a high capacity retention of 74% is observed. These cathodes have a higher sulfur content than those of conventional CNT hosts but nevertheless exhibit excellent performance. Our CNTPs and pore control technology will advance the commercialization of CNT hosts for LSBs.

γ-Fe₂O₃ Nanocrystalline Microspheres with Hybrid Behavior of Battery-Supercapacitor for Superior Lithium Storage.

PubMed

Tian, Lei-Lei; Zhang, Ming-Jian; Wu, Chao; Wei, Yi; Zheng, Jia-Xin; Lin, Ling-Piao; Lu, Jun; Amine, Khalil; Zhuang, Quan-Chao; Pan, Feng

2015-12-02

Maghemite (γ-Fe2O3) nanocrystalline microspheres (MNMs) self-assembled with 52 nm nanocrystals bridged with FeOOH around grain boundaries were formed by solvothermal reaction and thermal oxidation. The unique architecture endows the MNMs with the lithium storage behavior of a hybrid battery-supercapacitor electrode: initial charge capacity of 1060 mAh g(-1) at the 100 mA g(-1) rate, stable cyclic capacity of 1077.9 mAh g(-1) at the same rate after 140 cycles, and rate capability of 538.8 mAh g(-1) at 2400 mA g(-1). This outstanding performance was attributed to the nanocrystal superiority, which shortens the Li(+) diffusion paths. The mechanism of this hybrid anode material was investigated with experimental measurements and structural analysis. The results indicate that at the first discharge, the MNM nanocrystal microsphere, whose structure can buffer the volume change that occurs during lithiation/delithiation, goes through four stages: Li(+) insertion in cation vacancies, spinel-to-rocksalt transformation, Li(+) intercalation of Li(1.75+x)Fe2O3 nanocrystals, and interfacial Li storage around nanocrystal boundaries. Only the latter two stages were reversible at and after the second charging/discharging cycle, exhibiting the hybrid behavior of a battery-supercapacitor with superior lithium storage.

Scalable shear-exfoliation of high-quality phosphorene nanoflakes with reliable electrochemical cycleability in nano batteries

NASA Astrophysics Data System (ADS)

Xu, Feng; Ge, Binghui; Chen, Jing; Nathan, Arokia; Xin, Linhuo L.; Ma, Hongyu; Min, Huihua; Zhu, Chongyang; Xia, Weiwei; Li, Zhengrui; Li, Shengli; Yu, Kaihao; Wu, Lijun; Cui, Yiping; Sun, Litao; Zhu, Yimei

2016-06-01

Atomically thin black phosphorus (called phosphorene) holds great promise as an alternative to graphene and other two-dimensional transition-metal dichalcogenides as an anode material for lithium-ion batteries (LIBs). However, bulk black phosphorus (BP) suffers from rapid capacity fading and poor rechargeable performance. This work reports for the first time the use of in situ transmission electron microscopy (TEM) to construct nanoscale phosphorene LIBs. This enables direct visualization of the mechanisms underlying capacity fading in thick multilayer phosphorene through real-time capture of delithiation-induced structural decomposition, which serves to reduce electrical conductivity thus causing irreversibility of the lithiated phases. We further demonstrate that few-layer-thick phosphorene successfully circumvents the structural decomposition and holds superior structural restorability, even when subject to multi-cycle lithiation/delithiation processes and concomitant huge volume expansion. This finding provides breakthrough insights into thickness-dependent lithium diffusion kinetics in phosphorene. More importantly, a scalable liquid-phase shear exfoliation route has been developed to produce high-quality ultrathin phosphorene using simple means such as a high-speed shear mixer or even a household kitchen blender with the shear rate threshold of ˜1.25 × 104 s-1. The results reported here will pave the way for industrial-scale applications of rechargeable phosphorene LIBs.

Metal-Organic Framework Derived Porous Hollow Co3O4/N-C Polyhedron Composite with Excellent Energy Storage Capability.

PubMed

Kang, Wenpei; Zhang, Yu; Fan, Lili; Zhang, Liangliang; Dai, Fangna; Wang, Rongming; Sun, Daofeng

2017-03-29

Metal-organic frameworks (MOFs) derived transition metal oxides exhibit enhanced performance in energy conversion and storage. In this work, porous hollow Co 3 O 4 with N-doped carbon coating (Co 3 O 4 /N-C) polyhedrons have been prepared using cobalt-based MOFs as a sacrificial template. Assembled from tiny nanoparticles and N-doped carbon coating, Co 3 O 4 /N-C composite shortens the diffusion length of Li + /Na + ions and possesses an enhanced conductivity. And the porous and hollow structure is also beneficial for tolerating volume changes in the galvanostatic discharge/charge cycles as lithium/sodium battery anode materials. As a result, it can exhibit impressive cycling and rating performance. At 1000 mA g -1 , the specific capacities maintaine stable values of ∼620 mAh g -1 within 2000 cycles as anodes in lithium ion battery, while the specific capacity keeps at 229 mAh g -1 within 150 cycles as sodium ion battery anode. Our work shows comparable cycling performance in lithium ion battery but even better high-rate cycling stability as sodium ion battery anode. Herein, we provide a facile method to construct high electrochemical performance oxide/N-C composite electrode using new MOFs as sacrificial template.

Scalable shear-exfoliation of high-quality phosphorene nanoflakes with reliable electrochemical cycleability in nano batteries

DOE PAGES

Xu, Feng; Ge, Binghui; Chen, Jing; ...

2016-03-30

Atomically thin black phosphorus (called phosphorene) holds great promise as an alternative to graphene and other two-dimensional transition-metal dichalcogenides as an anode material for lithium-ion batteries (LIBs). But, bulk black phosphorus (BP) suffers from rapid capacity fading and poor rechargeable performance. This work reports for the first time the use of in situ transmission electron microscopy (TEM) to construct nanoscale phosphorene LIBs. This enables direct visualization of the mechanisms underlying capacity fading in thick multilayer phosphorene through real-time capture of delithiation-induced structural decomposition, which serves to reduce electrical conductivity thus causing irreversibility of the lithiated phases. Furthermore, we demonstrate thatmore » few-layer-thick phosphorene successfully circumvents the structural decomposition and holds superior structural restorability, even when subject to multi-cycle lithiation/delithiation processes and concomitant huge volume expansion. This finding provides breakthrough insights into thickness-dependent lithium diffusion kinetics in phosphorene. More importantly, a scalable liquid-phase shear exfoliation route has been developed to produce high-quality ultrathin phosphorene using simple means such as a high-speed shear mixer or even a household kitchen blender with the shear rate threshold of ~1.25 × 10 4 s -1. Our results reported here will pave the way for industrial-scale applications of rechargeable phosphorene LIBs.« less

Toward Aerogel Electrodes of Superior Rate Performance in Supercapacitors through Engineered Hollow Nanoparticles of NiCo2O4.

PubMed

Li, Jianjiang; Chen, Shuai; Zhu, Xiaoyi; She, Xilin; Liu, Tongchao; Zhang, Huawei; Komarneni, Sridhar; Yang, Dongjiang; Yao, Xiangdong

2017-12-01

A biomass-templated pathway is developed for scalable synthesis of NiCo 2 O 4 @carbon aerogel electrodes for supercapacitors, where NiCo 2 O 4 hollow nanoparticles with an average outer diameter of 30-40 nm are conjoined by graphitic carbon forming a 3D aerogel structure. This kind of NiCo 2 O 4 aerogel structure shows large specific surface area (167.8 m 2 g -1 ), high specific capacitance (903.2 F g -1 at a current density of 1 A g -1 ), outstanding rate performance (96.2% capacity retention from 1 to 10 A g -1 ), and excellent cycling stability (nearly without capacitance loss after 3000 cycles at 10 A g -1 ). The unique structure of the 3D hollow aerogel synergistically contributes to the high performance. For instance, the 3D interconnected porous structure of the aerogel is beneficial for electrolyte ion diffusion and for shortening the electron transport pathways, and thus can improve the rate performance. The conductive carbon joint greatly enhances the specific capacity, and the hollow structure prohibits the volume changes during the charge-discharge process to significantly improve the cycling stability. This work represents a giant step toward the preparation of high-performance commercial supercapacitors.