Oxygen partial pressure sensor

DOEpatents

Dees, D.W.

1994-09-06

A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured. 1 fig.

Oxygen partial pressure sensor

DOEpatents

Dees, Dennis W.

1994-01-01

A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured.

Oxygen partial pressure influenced structural and optical properties of DC magnetron sputtered ZrO{sub 2} films

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

Kondaiah, P.; Madhavi, V.; Uthanna, S.

2013-02-05

Thin films of zirconium oxide (ZrO{sub 2}) were deposited on (100) p-silicon and quartz substrates by sputtering of metallic zirconium target under different oxygen partial pressures in the range 8 Multiplication-Sign 10{sup -3}-6 Multiplication-Sign 10{sup -2}Pa. The effect of oxygen partial pressure on the structural and optical properties of the deposited films was systematically investigated. The deposition rate of the films decreased from 3.3 to 1.83 nm/min with the increase of oxygen partial pressure from 8 Multiplication-Sign 10{sup -3}-6 Multiplication-Sign 10{sup -2}Pa respectively. The X-ray diffraction profiles revealed that the films exhibit (111) refection of zirconium oxide in monoclinic phase.more » The optical band gap of the films increased from 5.62 to 5.80 eV and refractive index increased from 2.01 to 2.08 with the increase of oxygen partial pressure from 8 Multiplication-Sign 10{sup -3}-6 Multiplication-Sign 10{sup -2}Pa respectively.« less

Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model.

PubMed

Park, Marcelo; Mendes, Pedro Vitale; Costa, Eduardo Leite Vieira; Barbosa, Edzangela Vasconcelos Santos; Hirota, Adriana Sayuri; Azevedo, Luciano Cesar Pontes

2016-01-01

The aim of this study was to explore the factors associated with blood oxygen partial pressure and carbon dioxide partial pressure. The factors associated with oxygen - and carbon dioxide regulation were investigated in an apneic pig model under veno-venous extracorporeal membrane oxygenation support. A predefined sequence of blood and sweep flows was tested. Oxygenation was mainly associated with extracorporeal membrane oxygenation blood flow (beta coefficient = 0.036mmHg/mL/min), cardiac output (beta coefficient = -11.970mmHg/L/min) and pulmonary shunting (beta coefficient = -0.232mmHg/%). Furthermore, the initial oxygen partial pressure and carbon dioxide partial pressure measurements were also associated with oxygenation, with beta coefficients of 0.160 and 0.442mmHg/mmHg, respectively. Carbon dioxide partial pressure was associated with cardiac output (beta coefficient = 3.578mmHg/L/min), sweep gas flow (beta coefficient = -2.635mmHg/L/min), temperature (beta coefficient = 4.514mmHg/ºC), initial pH (beta coefficient = -66.065mmHg/0.01 unit) and hemoglobin (beta coefficient = 6.635mmHg/g/dL). In conclusion, elevations in blood and sweep gas flows in an apneic veno-venous extracorporeal membrane oxygenation model resulted in an increase in oxygen partial pressure and a reduction in carbon dioxide partial pressure 2, respectively. Furthermore, without the possibility of causal inference, oxygen partial pressure was negatively associated with pulmonary shunting and cardiac output, and carbon dioxide partial pressure was positively associated with cardiac output, core temperature and initial hemoglobin.

Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model

PubMed Central

Park, Marcelo; Mendes, Pedro Vitale; Costa, Eduardo Leite Vieira; Barbosa, Edzangela Vasconcelos Santos; Hirota, Adriana Sayuri; Azevedo, Luciano Cesar Pontes

2016-01-01

Objective The aim of this study was to explore the factors associated with blood oxygen partial pressure and carbon dioxide partial pressure. Methods The factors associated with oxygen - and carbon dioxide regulation were investigated in an apneic pig model under veno-venous extracorporeal membrane oxygenation support. A predefined sequence of blood and sweep flows was tested. Results Oxygenation was mainly associated with extracorporeal membrane oxygenation blood flow (beta coefficient = 0.036mmHg/mL/min), cardiac output (beta coefficient = -11.970mmHg/L/min) and pulmonary shunting (beta coefficient = -0.232mmHg/%). Furthermore, the initial oxygen partial pressure and carbon dioxide partial pressure measurements were also associated with oxygenation, with beta coefficients of 0.160 and 0.442mmHg/mmHg, respectively. Carbon dioxide partial pressure was associated with cardiac output (beta coefficient = 3.578mmHg/L/min), sweep gas flow (beta coefficient = -2.635mmHg/L/min), temperature (beta coefficient = 4.514mmHg/ºC), initial pH (beta coefficient = -66.065mmHg/0.01 unit) and hemoglobin (beta coefficient = 6.635mmHg/g/dL). Conclusion In conclusion, elevations in blood and sweep gas flows in an apneic veno-venous extracorporeal membrane oxygenation model resulted in an increase in oxygen partial pressure and a reduction in carbon dioxide partial pressure 2, respectively. Furthermore, without the possibility of causal inference, oxygen partial pressure was negatively associated with pulmonary shunting and cardiac output, and carbon dioxide partial pressure was positively associated with cardiac output, core temperature and initial hemoglobin. PMID:27096671

Effect of O 2 gas partial pressure on structures and dielectric characteristics of rf sputtered ZrO 2 thin films

NASA Astrophysics Data System (ADS)

Ma, C. Y.; Lapostolle, F.; Briois, P.; Zhang, Q. Y.

2007-08-01

Amorphous and polycrystalline zirconium oxide thin films have been deposited by reactive rf magnetron sputtering in a mixed argon/oxygen or pure oxygen atmosphere with no intentional heating of the substrate. The films were characterized by high-resolution transmission electron microscopy (HR-TEM), atomic force microscopy (AFM), spectroscopic ellipsometry (SE), and capacitance versus voltage ( C- V) measurements to investigate the variation of structure, surface morphology, thickness of SiO 2-like interfacial layer as well as dielectric characteristics with different oxygen partial pressures. The films deposited at low oxygen partial pressures (less than 15%) are amorphous and dense with a smooth surface. In contrast, the films prepared at an oxygen partial pressure higher than 73% are crystallized with the microstructure changing from the mixture of monoclinic and tetragonal phases to a single monoclinic structure. The film structural transition is believed to be consequences of decrease in the oxygen vacancy concentration in the film and of increase of the energetically neutral particles in the plasma due to an increased oxygen partial pressure. SE measurements showed that significant interfacial SiO 2 growth has taken place above approximately 51%. The best C- V results in terms of relative dielectric constant values are obtained for thin films prepared at an oxygen partial pressure of 15%.

Efficient absorption of SO2 with low-partial pressures by environmentally benign functional deep eutectic solvents.

PubMed

Zhang, Kai; Ren, Shuhang; Hou, Yucui; Wu, Weize

2017-02-15

Sulfur dioxide (SO 2 ) emitted from the burning of fossil fuels is one of the main air contaminants. In this work, we found that environmentally benign solvents, deep eutectic solvents (DESs) could be designed with a function to absorb low-partial pressure SO 2 from simulated flue gas. Two kinds of biodegradable functional DESs based on betaine (Bet) and l-carnitine (L-car) as hydrogen bond accepters (HBA) and ethylene glycol (EG) as a hydrogen bond donor (HBD) were prepared with mole ratios of HBA to HBD from 1:3 to 1:5, and they were investigated to absorb SO 2 with different partial pressures at various temperatures. The results showed that the two DESs could absorb low-partial pressure SO 2 efficiently. SO 2 absorption capacities of the DESs with HBA/HBD mole ratio of 1:3 were 0.332mol SO 2 /mol HBA for Bet+EG DES and 0.820mol SO 2 /mol HBA for L-car+EG DES at 40°C with a SO 2 partial pressure of 0.02atm. In addition, the regeneration experiments demonstrated that the absorption capacities of DESs did not change after five absorption and desorption cycles. Furthermore, the absorption mechanism of SO 2 by DESs was studied by FT-IR, 1 H NMR and 13 C NMR spectra. It was found that there are strong acid-base interactions between SO 2 and -COO - on HBA. Copyright © 2016 Elsevier B.V. All rights reserved.

Report on ISS O2 Production, Gas Supply and Partial Pressure Management

NASA Technical Reports Server (NTRS)

Schaezler, Ryan N.; Cook, Anthony J.

2015-01-01

Oxygen is used on International Space Station (ISS) for metabolic support and denitrogenation procedures prior to Extra-Vehicular Activities. Nitrogen is used to maintain total pressure and account for losses associated with leakage and operational losses. Oxygen and nitrogen have been supplied by various visiting vehicles such as the Progress and Shuttle in addition to the on-orbit oxygen production capability. Starting in 2014, new high pressure oxygen/nitrogen tanks are available to launch on commercial cargo vehicles and will replace the high pressure gas source that Shuttle used to provide. To maintain a habitable atmosphere the oxygen and nitrogen partial pressures are controlled between upper and lower bounds. The full range of the allowable partial pressures along with the increased ISS cabin volume are utilized as a buffer allowing days to pass between oxygen production or direct addition of oxygen and nitrogen to the atmosphere from reserves. This paper summarizes the amount of gas supplied and produced from all of the sources and describes past experience of managing partial pressures along with the range of management options available to the ISS.

Effects of oxygen partial pressure on Li-air battery performance

NASA Astrophysics Data System (ADS)

Kwon, Hyuk Jae; Lee, Heung Chan; Ko, Jeongsik; Jung, In Sun; Lee, Hyun Chul; Lee, Hyunpyo; Kim, Mokwon; Lee, Dong Joon; Kim, Hyunjin; Kim, Tae Young; Im, Dongmin

2017-10-01

For application in electric vehicles (EVs), the Li-air battery system needs an air intake system to supply dry oxygen at controlled concentration and feeding rate as the cathode active material. To facilitate the design of such air intake systems, we have investigated the effects of oxygen partial pressure (≤1 atm) on the performance of the Li-air cell, which has not been systematically examined. The amounts of consumed O2 and evolved CO2 from the Li-air cell are measured with a custom in situ differential electrochemical gas chromatography-mass spectrometry (DEGC-MS). The amounts of consumed O2 suggest that the oxygen partial pressure does not affect the reaction mechanism during discharge, and the two-electron reaction occurs under all test conditions. On the other hand, the charging behavior varies by the oxygen partial pressure. The highest O2 evolution ratio is attained under 70% O2, along with the lowest CO2 evolution. The cell cycle life also peaks at 70% O2 condition. Overall, an oxygen partial pressure of about 0.5-0.7 atm maximizes the Li-air cell capacity and stability at 1 atm condition. The findings here indicate that the appropriate oxygen partial pressure can be a key factor when developing practical Li-air battery systems.

A System for Incubations at High Gas Partial Pressure

PubMed Central

Sauer, Patrick; Glombitza, Clemens; Kallmeyer, Jens

2012-01-01

High-pressure is a key feature of deep subsurface environments. High partial pressure of dissolved gasses plays an important role in microbial metabolism, because thermodynamic feasibility of many reactions depends on the concentration of reactants. For gases, this is controlled by their partial pressure, which can exceed 1 MPa at in situ conditions. Therefore, high hydrostatic pressure alone is not sufficient to recreate true deep subsurface in situ conditions, but the partial pressure of dissolved gasses has to be controlled as well. We developed an incubation system that allows for incubations at hydrostatic pressure up to 60 MPa, temperatures up to 120°C, and at high gas partial pressure. The composition and partial pressure of gasses can be manipulated during the experiment. To keep costs low, the system is mainly made from off-the-shelf components with only very few custom-made parts. A flexible and inert PVDF (polyvinylidene fluoride) incubator sleeve, which is almost impermeable for gases, holds the sample and separates it from the pressure fluid. The flexibility of the incubator sleeve allows for sub-sampling of the medium without loss of pressure. Experiments can be run in both static and flow-through mode. The incubation system described here is usable for versatile purposes, not only the incubation of microorganisms and determination of growth rates, but also for chemical degradation or extraction experiments under high gas saturation, e.g., fluid–gas–rock-interactions in relation to carbon dioxide sequestration. As an application of the system we extracted organic compounds from sub-bituminous coal using H2O as well as a H2O–CO2 mixture at elevated temperature (90°C) and pressure (5 MPa). Subsamples were taken at different time points during the incubation and analyzed by ion chromatography. Furthermore we demonstrated the applicability of the system for studies of microbial activity, using samples from the Isis mud volcano. We could

Proximate nutritional composition of CELSS crops grown at different CO2 partial pressures

NASA Technical Reports Server (NTRS)

Wheeler, R. M.; Mackowiak, C. L.; Sager, J. C.; Knott, W. M.; Berry, W. L.

1994-01-01

Two Controlled Ecological Life Support System (CELSS) candidate crops, soybean (Glycine max) and potato (Solanum tuberosum), were grown hydroponically in controlled environments maintained at carbon dioxide (CO2) partial pressures ranging from 0.05 to 1.00 kPa (500 to 10,000 ppm at 101 kPa atmospheric pressure). Plants were harvested at maturity (90 days for soybean and 105 days for potato) and all tissues analyzed for proximate nutritional composition (i.e. protein, fat, carbohydrate, crude fiber, and ash content). Soybean seed ash and crude fiber were higher and carbohydrate was lower than values reported for field-grown seed. Potato tubers showed little difference from field-grown tubers. Crude fiber of soybean stems and leaves increased with increased CO2, as did soybean leaf protein (total nitrogen). Potato leaf and stem (combined) protein levels also increased with increased CO2, while leaf and stem carbohydrates decreased. Values for leaf and stem protein and ash were higher than values generally reported for field-grown plants for both species. Results suggest that CO2 partial pressure should have little influence on proximate composition of potato tubers or soybean seed, but that high ash and protein levels might be expected from leaves and stems of crops grown in controlled environments of a CELSS.

Formation mechanisms of Si3N4 and Si2N2O in silicon powder nitridation

NASA Astrophysics Data System (ADS)

Yao, Guisheng; Li, Yong; Jiang, Peng; Jin, Xiuming; Long, Menglong; Qin, Haixia; Kumar, R. Vasant

2017-04-01

Commercial silicon powders are nitrided at constant temperatures (1453 K; 1513 K; 1633 K; 1693 K). The X-ray diffraction results show that small amounts of Si3N4 and Si2N2O are formed as the nitridation products in the samples. Fibroid and short columnar Si3N4 are detected in the samples. The formation mechanisms of Si3N4 and Si2N2O are analyzed. During the initial stage of silicon powder nitridation, Si on the outside of sample captures slight amount of O2 in N2 atmosphere, forming a thin film of SiO2 on the surface which seals the residual silicon inside. And the oxygen partial pressure between the SiO2 film and free silicon is decreasing gradually, so passive oxidation transforms to active oxidation and metastable SiO(g) is produced. When the SiO(g) partial pressure is high enough, the SiO2 film will crack, and N2 is infiltrated into the central section of the sample through cracks, generating Si2N2O and short columnar Si3N4 in situ. At the same time, metastable SiO(g) reacts with N2 and form fibroid Si3N4. In the regions where the oxygen partial pressure is high, Si3N4 is oxidized into Si2N2O.

21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. 868.1150 Section 868.1150 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... “Class II Special Controls Guidance Document: Indwelling Blood Gas Analyzers; Final Guidance for Industry...

Effect of CO2 partial pressure and different CO2 phases on carbon steel corrosion

NASA Astrophysics Data System (ADS)

Mahlobo, MGR; Premlall, K.; Olubambi, PA

2017-12-01

Carbon capture and storage (CCS) is the recent promising technology aimed at reducing greenhouse gas emission. Like many other developed technologies, CCS is faced with great challenges such as pipeline transportation failure due to corrosion. There are many factors contributing to steel corrosion during the pipeline transportation of carbon dioxide (CO2). This study focuses on CO2 partial pressure and different phases of CO2 as some of the factors contributing to steel corrosion. Carbon steel was used as a testing specimen. High pressure reactor was used in this study to compress CO2 from low to high pressures ultimately changing the CO2 from gaseous phase to gas/liquid phase (subcritical) and to dense phase (supercritical). Weight loss method was employed to determine the corrosion rate while scanning electron microscopy (SEM) and X-Ray diffraction (XRD) were used to study the carbon steel morphology and phase analysis. Using low magnification digital camera, the type of corrosion that took place on the carbon steel surface was identified.

Pressures of Partial Crystallization of Magmas Along Transforms: Implications for Crustal Accretion

NASA Astrophysics Data System (ADS)

Scott, J. L.; Zerda, C.; Brown, D.; Ciaramitaro, S. C.; Barton, M.

2016-12-01

Plate spreading at mid-ocean ridges is responsible for the creation of most of the crust on earth. The ridge system is very complex and many questions remain unresolved. Among these is the nature of magma plumbing systems beneath transform faults. Pervious workers have suggested that increased conductive cooling along transforms promotes higher pressures of partial crystallization, and that this explains the higher partial pressures of crystallization inferred for magmas erupted along slow spreading ridges compared to magmas erupted along faster spreading ridges. To test this hypothesis, we undertook a detailed analysis of pressures of partial crystallization for magmas erupted at 3 transforms along the fast to intermediate spreading East Pacific Rise(Blanco, Clipperton, and Siqueiros) and 3 transforms along the slow spreading Mid Atlantic Ridge(Famous Transform B, Kane, and 15°20'N). Pressures of partial crystallization were calculated from the compositions of glasses (quenched liquids) lying along the P (and T) dependent olivine, plagioclase, and augite cotectic using the method described by Kelley and Barton (2008). Published analyses of mid-ocean ridge basalt glasses sampled from these transforms and surrounding ridge segments were used as input data. Samples with anomalous chemical compositions and samples that yielded pressures associated with unrealistically large uncertainties were filtered out of the database. The pressures of partial crystallization for the remaining 916 samples ranged from 0 to 520 MPa with the great majority ( 95%) of sample returning pressures of less than 300 MPa. Pressures of < 300 MPa are within error of the pressure range associated with partial crystallization within oceanic crust with a thickness of 7 km. Higher (sub-crustal) pressures (>300 MPa) are associated with a small number of samples from the Pacific segments. Except for the Blanco, pressures of partial crystallization do not increase as transforms are approached. These

Thin film devices used as oxygen partial pressure sensors

NASA Technical Reports Server (NTRS)

Canady, K. S.; Wortman, J. J.

1970-01-01

Electrical conductivity of zinc oxide films to be used in an oxygen partial pressure sensor is measured as a function of temperature, oxygen partial pressure, and other atmospheric constituents. Time response following partial pressure changes is studied as a function of temperature and environmental changes.

[Device to assess in-socket pressure distribution for partial foot amputation].

PubMed

Alvarez-Camacho, Michelín; Urrusti, José Luis; Acero, María Del Carmen; Galván Duque-Gastélum, Carlos; Rodríguez-Reyes, Gerardo; Mendoza-Cruz, Felipe

2014-07-01

A device for dynamic acquisition and distribution analysis of in-socket pressure for patients with partial foot amputation is presented in this work. By using the developed system, we measured and generated pressure distribution graphs, obtained maximal pressure, and calculated pressure-time integral (PTI) of three subjects with partial foot amputation and of a group of Healthy subjects (Hs) (n = 10). Average maximal pressure in the healthy group was 19.4 ± 4.11 PSI, while for the three amputated patients, this was 27.8 ± 1.38, 17.6 ± 1.15, 29.10 ± 3.9 PSI, respectively. Maximal pressure-time integral for healthy subjects was 11.56 ± 2.83 PSI*s, and for study subjects was 19.54 ± 1.9, 12.35 ± 1.48, and 13.17 ± 1.31 PSI*s, respectively. The results of the control group agree with those previously reported in the literature. The pressure distribution pattern showed clear differences between study subjects and those of the control group; these graphs allowed us to identify the pressure in regions-of-interest that could be critical, such as surgical scars. The system presented in this work will aid to assess the effectiveness with which prosthetic systems distribute load, given that the formation of ulcers is highly linked to the pressure exercised at the point of contact; in addition, these results will help to investigate the comfort perception of the prosthesis, a factor directly influenced by the stump's pressure distribution.

Thin film oxygen partial pressure sensor

NASA Technical Reports Server (NTRS)

Wortman, J. J.; Harrison, J. W.; Honbarrier, H. L.; Yen, J.

1972-01-01

The development is described of a laboratory model oxygen partial pressure sensor using a sputtered zinc oxide thin film. The film is operated at about 400 C through the use of a miniature silicon bar. Because of the unique resistance versus temperature relation of the silicon bar, control of the operational temperature is achieved by controlling the resistance. A circuit for accomplishing this is described. The response of sputtered zinc oxide films of various thicknesses to oxygen, nitrogen, argon, carbon dioxide, and water vapor caused a change in the film resistance. Over a large range, film conductance varied approximately as the square root of the oxygen partial pressure. The presence of water vapor in the gas stream caused a shift in the film conductance at a given oxygen partial pressure. A theoretical model is presented to explain the characteristic features of the zinc oxide response to oxygen.

Tibiofemoral contact pressures in radial tears of the meniscus treated with all-inside repair, inside-out repair and partial meniscectomy.

PubMed

Zhang, Alan L; Miller, Stephanie L; Coughlin, Dezba G; Lotz, Jeffrey C; Feeley, Brian T

2015-10-01

To test contact pressures in the knee after treatment of a radial meniscus tear with an all-inside meniscal repair technique and compare the results with inside-out repair and partial meniscectomy. Six non-paired cadaveric knees were analyzed with intra-compartment pressures measured at loads of 250 N, 500 N and 1000 N at 0°, eight degrees, 15°, and 30° of knee flexion. Compartmental contact pressures were measured for the intact medial meniscus, radial tear in the posterior horn, all-inside repair using the NovoStitch suture passer device (Ceterix Orthopaedics Inc., Menlo Park, CA), inside-out repair method, and partial meniscectomy. One-way ANOVA was used for statistical analysis. The greatest differences in peak pressures between treatments were observed under 1000 N load at 30° flexion (0.8± (SD) 0.1 MPa (intact meniscus), 0.8± (SD) 0.1 MPa (all-inside), 0.9± (SD) 0.1 MPa (inside-out) and 1.6± (SD) 0.2 MPa (partial meniscectomy)). Treatment with partial meniscectomy resulted in the highest peak pressures compared to all other states (p<0.0001 at each angle). Repair of the radial tear using the all-inside technique as well as the inside-out technique resulted in significantly decreased compartment pressures compared to partial meniscectomies (p<0.0001 at each angle). There were no significant differences between peak pressures in the intact state and after repair with the all-inside or inside-out techniques. An all-inside repair technique using the NovoStitch suture passer can decrease contact pressures for a radial meniscus tear similarly to the inside-out repair technique when compared to partial meniscectomy. This novel arthroscopic suture passer warrants further analysis in the clinical setting as it may be a reliable method for repair of radial meniscal tears through an arthroscopic all-inside technique. Copyright © 2015 Elsevier B.V. All rights reserved.

Bulk YBa2Cu3O(x) superconductors through pressurized partial melt growth processing

NASA Technical Reports Server (NTRS)

Hu, S.; Hojaji, H.; Barkatt, A.; Boroomand, M.; Hung, M.; Buechele, A. C.; Thorpe, A. N.; Davis, D. D.; Alterescu, S.

1992-01-01

A novel pressurized partial melt growth process has been developed for producing large pieces of bulk Y-Ba-Cu-O superconductors. During long-time partial melt growth stage, an additional driving force for solidification is obtained by using pressurized oxygen gas. The microstructure and superconducting properties of the resulting samples were investigated. It was found that this new technique can eliminate porosity and inhomogeneity, promote large-scale grain-texturing, and improve interdomain coupling as well.

Photosynthetic induction and its diffusional, carboxylation and electron transport processes as affected by CO2 partial pressure, temperature, air humidity and blue irradiance.

PubMed

Kaiser, Elias; Kromdijk, Johannes; Harbinson, Jeremy; Heuvelink, Ep; Marcelis, Leo F M

2017-01-01

Plants depend on photosynthesis for growth. In nature, factors such as temperature, humidity, CO 2 partial pressure, and spectrum and intensity of irradiance often fluctuate. Whereas irradiance intensity is most influential and has been studied in detail, understanding of interactions with other factors is lacking. We tested how photosynthetic induction after dark-light transitions was affected by CO 2 partial pressure (20, 40, 80 Pa), leaf temperatures (15·5, 22·8, 30·5 °C), leaf-to-air vapour pressure deficits (VPD leaf-air ; 0·5, 0·8, 1·6, 2·3 kPa) and blue irradiance (0-20 %) in tomato leaves (Solanum lycopersicum). Rates of photosynthetic induction strongly increased with CO 2 partial pressure, due to increased apparent Rubisco activation rates and reduced diffusional limitations. High leaf temperature produced slightly higher induction rates, and increased intrinsic water use efficiency and diffusional limitation. High VPD leaf-air slowed down induction rates and apparent Rubisco activation and (at 2·3 kPa) induced damped stomatal oscillations. Blue irradiance had no effect. Slower apparent Rubisco activation in elevated VPD leaf-air may be explained by low leaf internal CO 2 partial pressure at the beginning of induction. The environmental factors CO 2 partial pressure, temperature and VPD leaf-air had significant impacts on rates of photosynthetic induction, as well as on underlying diffusional, carboxylation and electron transport processes. Furthermore, maximizing Rubisco activation rates would increase photosynthesis by at most 6-8 % in ambient CO 2 partial pressure (across temperatures and humidities), while maximizing rates of stomatal opening would increase photosynthesis by at most 1-3 %. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Fixed point and anomaly mediation in partial {\\boldsymbol{N}}=2 supersymmetric standard models

NASA Astrophysics Data System (ADS)

Yin, Wen

2018-01-01

Motivated by the simple toroidal compactification of extra-dimensional SUSY theories, we investigate a partial N = 2 supersymmetric (SUSY) extension of the standard model which has an N = 2 SUSY sector and an N = 1 SUSY sector. We point out that below the scale of the partial breaking of N = 2 to N = 1, the ratio of Yukawa to gauge couplings embedded in the original N = 2 gauge interaction in the N = 2 sector becomes greater due to a fixed point. Since at the partial breaking scale the sfermion masses in the N = 2 sector are suppressed due to the N = 2 non-renormalization theorem, the anomaly mediation effect becomes important. If dominant, the anomaly-induced masses for the sfermions in the N = 2 sector are almost UV-insensitive due to the fixed point. Interestingly, these masses are always positive, i.e. there is no tachyonic slepton problem. From an example model, we show interesting phenomena differing from ordinary MSSM. In particular, the dark matter particle can be a sbino, i.e. the scalar component of the N = 2 vector multiplet of {{U}}{(1)}Y. To obtain the correct dark matter abundance, the mass of the sbino, as well as the MSSM sparticles in the N = 2 sector which have a typical mass pattern of anomaly mediation, is required to be small. Therefore, this scenario can be tested and confirmed in the LHC and may be further confirmed by the measurement of the N = 2 Yukawa couplings in future colliders. This model can explain dark matter, the muon g-2 anomaly, and gauge coupling unification, and relaxes some ordinary problems within the MSSM. It is also compatible with thermal leptogenesis.

Annealing of gallium nitride under high-N 2 pressure

NASA Astrophysics Data System (ADS)

Porowski, S.; Jun, J.; Krukowski, S.; Grzegory, I.; Leszczynski, M.; Suski, T.; Teisseyre, H.; Foxon, C. T.; Korakakis, D.

1999-04-01

GaN is the key material for blue and ultraviolet optoelectronics. It is a strongly bonded wurztite structure semiconductor with the direct energy gap 3.5 eV. Due to strong bonding, the diffusion processes require high temperatures, above 1300 K. However at this temperature range at ambient pressure, GaN becomes unstable and dissociates into Ga and N 2. Therefore high pressure of N 2 is required to study the diffusion and other annealing related processes. We studied annealing of bulk GaN nitride single crystals grown under high pressure and also annealing of homo- and heteroepitaxial GaN layers grown by MOCVD technique. Annealing at temperatures above 1300 K influences strongly the structural and optical properties of GaN crystals and layers. At this temperature diffusion of the Mg and Zn acceptors have been observed. In spite of very interesting experimental observations the understanding of microscopic mechanisms of these processes is limited.

Spatial and Temporal Variations in the Partial Pressure and Emission of CO2 and CH4 in and Amazon Floodplain Lake

NASA Astrophysics Data System (ADS)

Forsberg, B. R.; Amaral, J. H.; Barbosa, P.; Kasper, D.; MacIntyre, S.; Cortes, A.; Sarmento, H.; Borges, A. V.; Melack, J. M.; Farjalla, V.

2015-12-01

The Amazon floodplain contains a variety of wetland environments which contribute CO2 and CH4 to the regional and global atmospheres. The partial pressure and emission of these greenhouse gases (GHGs) varies: 1) between habitats, 2) seasonally, as the characteristics these habitats changes and 3) diurnally, in response to diurnal stratification. In this study, we investigated the combined influence of these factors on the partial pressure and emission of GHGs in Lago Janauacá, a central Amazon floodplain lake (3o23' S; 60o18' O). All measurements were made between August of 2014 and April of 2015 at two different sites and in three distinct habitats: open water, flooded forest, flooded macrophytes. Concentrations of CO2 and CH4 in air were measured continuously with a cavity enhanced absorption spectrometer, Los Gatos Research´s Ultraportable Greenhouse Gas Analyzer (UGGA). Vertical profiles o pCO2 and pCH4 were measured using the UGGA connected to an electric pump and equilibrator. Diffusive surface emissions were estimated with the UGGA connected to a static floating chamber. To investigate the influence of vertical stratification and mixing on GHG partial pressure and emissions, a meteorological station and submersible sensor chain were deployed at each site. Meteorological sensors included wind speed and direction. The submersible chains included thermistors and oxygen sensors. Depth profiles of partial pressure and diffusive emissions for both CO2 and CH4 varied diurnally, seasonally and between habitats. Both pCO2 and pCH4 were consistently higher in bottom than surface waters with the largest differences occurring at high water when thermal stratification was most stable. Methane emissions and partial pressures were highest at low water while pCO2 and CO2 fluxes were highest during high water periods, with 35% of CO2 fluxes at low water being negative. The highest average surface value of pCO2 (5491 μatm), encountered during rising water, was ~3 times

A blackbody-pumped CO2-N2 transfer laser

NASA Astrophysics Data System (ADS)

Deyoung, R. J.; Higdon, N. S.

1984-08-01

A compact blackbody-pumped CO2-N2 transfer laser was constructed and the significant operating parameters were investigated. Lasing was achieved at 10.6 microns by passing preheated N2 through a 1.5-mm-diameter nozzle to a laser cavity where the N2 was mixed with CO2 and He. An intrinsic efficiency of 0.7 percent was achieved for an oven temperature of 1473 K and N2 oven pressure of 440 torr. The optimum laser cavity consisted of a back mirror with maximum reflectivity and an output mirror with 97.5-percent reflectivity. The optimum gas mixture was 1CO2/.5He/6N2. The variation of laser output was measured as a function of oven temperature, nozzle diameter, N2 oven pressure, He and CO2 partial pressures, nozzle-to-oven separation, laser cell temperature, and output laser mirror reflectivity. With these parameters optimized, outputs approaching 1.4 watts were achieved.

A blackbody-pumped CO2-N2 transfer laser

NASA Technical Reports Server (NTRS)

Deyoung, R. J.; Higdon, N. S.

1984-01-01

A compact blackbody-pumped CO2-N2 transfer laser was constructed and the significant operating parameters were investigated. Lasing was achieved at 10.6 microns by passing preheated N2 through a 1.5-mm-diameter nozzle to a laser cavity where the N2 was mixed with CO2 and He. An intrinsic efficiency of 0.7 percent was achieved for an oven temperature of 1473 K and N2 oven pressure of 440 torr. The optimum laser cavity consisted of a back mirror with maximum reflectivity and an output mirror with 97.5-percent reflectivity. The optimum gas mixture was 1CO2/.5He/6N2. The variation of laser output was measured as a function of oven temperature, nozzle diameter, N2 oven pressure, He and CO2 partial pressures, nozzle-to-oven separation, laser cell temperature, and output laser mirror reflectivity. With these parameters optimized, outputs approaching 1.4 watts were achieved.

Biomass hydrolysis inhibition at high hydrogen partial pressure in solid-state anaerobic digestion.

PubMed

Cazier, E A; Trably, E; Steyer, J P; Escudie, R

2015-08-01

In solid-state anaerobic digestion, so-called ss-AD, biogas production is inhibited at high total solids contents. Such inhibition is likely caused by a slow diffusion of dissolved reaction intermediates that locally accumulate. In this study, we investigated the effect of H2 and CO2 partial pressure on ss-AD. Partial pressure of H2 and/or CO2 was artificially fixed, from 0 to 1 557mbars for H2 and from 0 to 427mbars for CO2. High partial pressure of H2 showed a significant effect on methanogenesis, while CO2 had no impact. At high [Formula: see text] , the overall substrate degradation decreased with no accumulation of metabolites from acidogenic bacteria, indicating that the hydrolytic activity was specifically impacted. Interestingly, such inhibition did not occur when CO2 was added with H2. This result suggests that CO2 gas transfer is probably a key factor in ss-AD from biomass. Copyright © 2015 Elsevier Ltd. All rights reserved.

Oxidation of C/SiC Composites at Reduced Oxygen Partial Pressures

NASA Technical Reports Server (NTRS)

Opila, E. J.; Serra, J. L.

2007-01-01

T-300 carbon fibers and T-300 carbon fiber reinforced silicon carbide composites (C/SiC) were oxidized in flowing reduced oxygen partial pressure environments at a total pressure of one atmosphere (0.5 atm O2, 0.05 atm O2 and 0.005 atm O2, balance argon). Experiments were conducted at four temperatures (816deg, 1149deg, 1343deg, and 1538 C). The oxidation kinetics were monitored using thermogravimetric analysis. T-300 fibers were oxidized to completion for times between 0.6 and 90 h. Results indicated that fiber oxidation kinetics were gas phase diffusion controlled. Oxidation rates had an oxygen partial pressure dependence with a power law exponent close to one. In addition, oxidation rates were only weakly dependent on temperature. The C/SiC coupon oxidation kinetics showed some variability, attributed to differences in the number and width of cracks in the SiC seal coat. In general, weight losses were observed indicating oxidation of the carbon fibers dominated the oxidation behavior. Low temperatures and high oxygen pressures resulted in the most rapid consumption of the carbon fibers. At higher temperatures, the lower oxidation rates were primarily attributed to crack closure due to SiC thermal expansion, rather than oxidation of SiC since these reduced rates were observed even at the lowest oxygen partial pressures where SiC oxidation is minimal.

Oxygen partial pressure effects on the RF sputtered p-type NiO hydrogen gas sensors

NASA Astrophysics Data System (ADS)

Turgut, Erdal; Çoban, Ömer; Sarıtaş, Sevda; Tüzemen, Sebahattin; Yıldırım, Muhammet; Gür, Emre

2018-03-01

NiO thin films were grown by Radio Frequency (RF) Magnetron Sputtering method under different oxygen partial pressures, which are 0.6 mTorr, 1.3 mTorr and 2.0 mTorr. The effects of oxygen partial pressures on the thin films were analyzed through Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Hall measurements. The change in the surface morphology of the thin films has been observed with the SEM and AFM measurements. While nano-pyramids have been obtained on the thin film grown at the lowest oxygen partial pressure, the spherical granules lower than 60 nm in size has been observed for the samples grown at higher oxygen partial pressures. The shift in the dominant XRD peak is realized to the lower two theta angle with increasing the oxygen partial pressures. XPS measurements showed that the Ni2p peak involves satellite peaks and two oxidation states of Ni, Ni2+ and Ni3+, have been existed together with the corresponding splitting in O1s spectrum. P-type conductivity of the grown NiO thin films are confirmed by the Hall measurements with concentrations on the order of 1013 holes/cm-3. Gas sensor measurements revealed minimum of 10% response to the 10 ppm H2 level. Enhanced responsivity of the gas sensor devices of NiO thin films is shown as the oxygen partial pressure increases.

Effects of Chamber Pressure and Partial Pressure of Water Vapor on Secondary Drying in Lyophilization.

PubMed

Searles, James A; Aravapalli, Sridhar; Hodge, Cody

2017-10-01

Secondary drying is the final step of lyophilization before stoppering, during which water is desorbed from the product to yield the final moisture content. We studied how chamber pressure and partial pressure of water vapor during this step affected the time course of water content of aqueous solutions of polyvinylpyrrolidone (PVP) in glass vials. The total chamber pressure had no effect when the partial pressure of water vapor was very low. However, when the vapor phase contained a substantial fraction of water vapor, the PVP moisture content was much higher. We carried out dynamic vapor sorption experiments (DVS) to demonstrate that the higher PVP moisture content was a straightforward result of the higher water vapor content in the lyophilizer. The results highlight that the partial pressure of water vapor is extremely important during secondary drying in lyophilization, and that lower chamber pressure set points for secondary drying may sometimes be justified as a strategy for ensuring low partial pressure of water vapor, especially for lyophilizers that do not inject dry gas to control pressure. These findings have direct application for process transfers/scale ups from freeze-dryers that do not inject dry gas for pressure control to those that do, and vice versa.

Oxygen Partial Pressure and Oxygen Concentration Flammability: Can They Be Correlated?

NASA Technical Reports Server (NTRS)

Harper, Susana A.; Juarez, Alfredo; Perez, Horacio, III; Hirsch, David B.; Beeson, Harold D.

2016-01-01

NASA possesses a large quantity of flammability data performed in ISS airlock (30% Oxygen 526mmHg) and ISS cabin (24.1% Oxygen 760 mmHg) conditions. As new programs develop, other oxygen and pressure conditions emerge. In an effort to apply existing data, the question arises: Do equivalent oxygen partial pressures perform similarly with respect to flammability? This paper evaluates how material flammability performance is impacted from both the Maximum Oxygen Concentration (MOC) and Maximum Total Pressures (MTP) perspectives. From these studies, oxygen partial pressures can be compared for both the MOC and MTP methods to determine the role of partial pressure in material flammability. This evaluation also assesses the influence of other variables on flammability performance. The findings presented in this paper suggest flammability is more dependent on oxygen concentration than equivalent partial pressure.

Partial nitrogen loss in SrTaO2N and LaTiO2N oxynitride perovskites

NASA Astrophysics Data System (ADS)

Chen, Daixi; Habu, Daiki; Masubuchi, Yuji; Torii, Shuki; Kamiyama, Takashi; Kikkawa, Shinichi

2016-04-01

SrTaO2N heated in a helium atmosphere began to release nitrogen of approximately 30 at% at 950 °C while maintaining the perovskite structure and its color changed from orange to dark green. Then it decomposed above 1200 °C to a black mixture of Sr1.4Ta0.6O2.73, Ta2N, and Sr5Ta4O15. The second decomposition was not clearly observed when SrTaO2N was heated in a nitrogen atmosphere below 1550 °C. After heating at 1500 °C for 3 h under a 0.2 MPa nitrogen atmosphere, the perovskite product became dark green and conductive. Structure refinement results suggested that the product was a mixture of tetragonal and cubic perovskites with a decreased ordering of N3-/O2-. The sintered body was changed to an n-type semiconductor after a partial loss of nitrogen to be reduced from the originally insulating SrTaO2N perovskite lattice. LaTiO2N was confirmed to have a similar cis-configuration of the TiO4N2 octahedron as that of TaO4N2 in SrTaO2N. It also released some of its nitrogen at 800 °C changing its color from brown to black and then decomposed to a mixture of LaTiO3, La2O3, and TiN at 1100 °C. These temperatures are lower than those in SrTaO2N.

Influence of Oxygen Partial Pressure during Processing on the Thermoelectric Properties of Aerosol-Deposited CuFeO2

PubMed Central

Stöcker, Thomas; Exner, Jörg; Schubert, Michael; Streibl, Maximilian; Moos, Ralf

2016-01-01

In the field of thermoelectric energy conversion, oxide materials show promising potential due to their good stability in oxidizing environments. Hence, the influence of oxygen partial pressure during synthesis on the thermoelectric properties of Cu-Delafossites at high temperatures was investigated in this study. For these purposes, CuFeO2 powders were synthetized using a conventional mixed-oxide technique. X-ray diffraction (XRD) studies were conducted to determine the crystal structures of the delafossites associated with the oxygen content during the synthesis. Out of these powders, films with a thickness of about 25 µm were prepared by the relatively new aerosol-deposition (AD) coating technique. It is based on a room temperature impact consolidation process (RTIC) to deposit dense solid films of ceramic materials on various substrates without using a high-temperature step during the coating process. On these dense CuFeO2 films deposited on alumina substrates with electrode structures, the Seebeck coefficient and the electrical conductivity were measured as a function of temperature and oxygen partial pressure. We compared the thermoelectric properties of both standard processed and aerosol deposited CuFeO2 up to 900 °C and investigated the influence of oxygen partial pressure on the electrical conductivity, on the Seebeck coefficient and on the high temperature stability of CuFeO2. These studies may not only help to improve the thermoelectric material in the high-temperature case, but may also serve as an initial basis to establish a defect chemical model. PMID:28773351

DEVICE FOR CONTROL OF OXYGEN PARTIAL PRESSURE

DOEpatents

Bradner, H.; Gordon, H.S.

1957-12-24

A device is described that can sense changes in oxygen partial pressure and cause a corresponding mechanical displacement sufficient to actuate meters, valves and similar devices. A piston and cylinder arrangement contains a charge of crystalline metal chelate pellets which have the peculiar property of responding to variations in the oxygen content of the ambient atmosphere by undergoing a change in dimension. A lever system amplifies the relative displacement of the piston in the cylinder, and actuates the controlled valving device. This partial pressure oxygen sensing device is useful in controlled chemical reactions or in respiratory devices such as the oxygen demand meters for high altitude aircraft.

High-pressure polymorphism of Pb F2 to 75 GPa

NASA Astrophysics Data System (ADS)

Stan, Camelia V.; Dutta, Rajkrishna; White, Claire E.; Prakapenka, Vitali; Duffy, Thomas S.

2016-07-01

Lead fluoride, Pb F2 , was investigated experimentally in the laser-heated diamond anvil cell by x-ray diffraction to pressures of 75 GPa at room temperature and to 64.5 GPa and 2430 K, as well as through first-principles density functional theory calculations up to 70 GPa. During room temperature compression, no discontinuous changes in the x-ray diffraction pattern or volume were observed, but the lattice parameters displayed highly anomalous trends between 10-22 GPa with enhanced compressibility along the a direction and reduced or even negative compressibility along b and c . Theoretical calculations of valence electron densities at 22 GPa showed that α -Pb F2 underwent a pressure-induced isosymmetric phase transition to a postcotunnite C o2Si structure and also revealed the detailed atomic rearrangements associated with the development of an extra Pb-F bond in the high-pressure phase. Our x-ray results and theoretical calculations are consistent with an isosymmetric phase transition smoothly occurring over 10-22 GPa rather than abruptly as previously suggested. The characteristic values for the cell constants a /c and (a +c )/b , which are used to distinguish among cotunnite-, C o2Si -, and N i2In -type phases, require modification based on our results. An equation of state fit yields a bulk modulus, K0, of 72(3) GPa for the cotunnite-type, and an ambient-pressure volume, V0, of 182 (2 ) Å3 , and K0=81 (4 ) GPa for the C o2Si -type phase when fixing the pressure derivative of the bulk modulus, K0 '=4 . Upon heating above 1200 K at pressures at or above 25.9 GPa, Pb F2 partially transformed to the hexagonal N i2In -type phase but wholly or partially reverted back to C o2Si -type phase upon temperature quench. From 43-65 GPa, nearly complete transformation to the N i2In -type Pb F2 was observed at high temperature, but the material partially transformed back to the orthorhombic phase upon temperature quench. Our results show that high-pressure behavior of Pb F

Partial pressure analysis in space testing

NASA Technical Reports Server (NTRS)

Tilford, Charles R.

1994-01-01

For vacuum-system or test-article analysis it is often desirable to know the species and partial pressures of the vacuum gases. Residual gas or Partial Pressure Analyzers (PPA's) are commonly used for this purpose. These are mass spectrometer-type instruments, most commonly employing quadrupole filters. These instruments can be extremely useful, but they should be used with caution. Depending on the instrument design, calibration procedures, and conditions of use, measurements made with these instruments can be accurate to within a few percent, or in error by two or more orders of magnitude. Significant sources of error can include relative gas sensitivities that differ from handbook values by an order of magnitude, changes in sensitivity with pressure by as much as two orders of magnitude, changes in sensitivity with time after exposure to chemically active gases, and the dependence of the sensitivity for one gas on the pressures of other gases. However, for most instruments, these errors can be greatly reduced with proper operating procedures and conditions of use. In this paper, data are presented illustrating performance characteristics for different instruments and gases, operating parameters are recommended to minimize some errors, and calibrations procedures are described that can detect and/or correct other errors.

[The influence of oxygen partial pressure change and vascularization of rabbit wound through negative pressure wound therapy].

PubMed

Yang, Fan; Hu, Duan; Bai, Xiang-jun; Zhang, Kun; Li, Ren-jie; Xue, Chen-chen

2012-07-01

To investigate the effect of vacuum sealing drainage (VSD) on variation of oxygen partial pressure (PtO2) and vascularization. The 12 cases of rabbit's wound models were undergoing the VSD (vacuum group, n = 6) or conventional therapy (conventional group, n = 6). Variation of PtO2 was measured by oxygen partial pressure admeasuring apparatus, expression of hypoxia inducible factor 1α (HIF-1α) mRNA was measured by real-time fluorescent quantitative PCR, content of vascular endothelial growth factor (VEGF) was measured by ELISA after tissue homogenate in 7 days. Vascular endothelial cell (VEC) and new blood capillary (NBC) of hematoxylin-eosin slice of tissue were counted by using light microscope. Average value of PtO2 of vacuum group was significant lower than conventional group (t = -99.780 to -5.305, P < 0.01). Expression of HIF-1α (30 minutes, 1, 6, 12 hours were 3.11 ± 0.07, 3.68 ± 0.26, 4.16 ± 0.13 and 3.91 ± 0.26 respectively) and content of VEGF (30 minutes, 1, 6, 12 hours were 103.3 ± 2.4, 134.2 ± 9.0, 167.8 ± 3.8 and 232.1 ± 9.5 respectively) of vacuum group were increased after 30 minutes and significant lower than conventional group (t = 13.038 - 80.208, P < 0.01), and both of them were reduced after 24 hours (P < 0.05). Counting numbers of VEC (2.47 ± 0.45 to 4.70 ± 0.38) and NBC (1.33 ± 0.49 to 4.33 ± 0.68) of vacuum group were increased at the same time-point and significant higher than conventional group (t = -0.670 to 16.500, P < 0.05). PtO2 of wound surface could be reduced significantly by VSD. Expression of HIF-1α and content of VEGF were increased by VSD for enhancing differentiated state of VEC and construction of NBC, which were better for vascularization and wound healing.

Investigations on structural, elastic, thermodynamic and electronic properties of TiN, Ti2N and Ti3N2 under high pressure by first-principles

NASA Astrophysics Data System (ADS)

Yang, Ruike; Zhu, Chuanshuai; Wei, Qun; Du, Zheng

2016-11-01

The lattice parameters, cell volume, elastic constants, bulk modulus, shear modulus, Young's modulus and Poisson's ratio are calculated at zero pressure, and their values are in excellent agreement with the available data, for TiN, Ti2N and Ti3N2. By using the elastic stability criteria, it is shown that the three structures are all stable. The brittle/ductile behaviors are assessed in the pressures from 0 GPa to 50 GPa. Our calculations present that the performances for TiN, Ti2N and Ti3N2 become from brittle to ductile with pressure rise. The Debye temperature rises as pressure increase. With increasing N content, the enhancement of covalent interactions and decline of metallicity lead to the increase of the micro-hardness. Their constant volume heat capacities increase rapidly in the lower temperature, at a given pressure. At higher temperature, the heat capacities are close to the Dulong-Petit limit, and the heat capacities of TiN and Ti2N are larger than that of c-BN. The thermal expansion coefficients of titanium nitrides are slightly larger than that of c-BN. The band structure and the total Density of States (DOS) are calculated at 0 GPa and 50 GPa. The results show that TiN and Ti2N present metallic character. Ti3N2 present semiconducting character. The band structures have some discrepancies between 0 GPa and 50 GPa. The extent of energy dispersion increases slightly at 50 GPa, which means that the itinerant character of electrons becomes stronger at 50 GPa. The main bonding peaks of TiN, Ti2N and Ti3N2 locate in the range from -10 to 10 eV, which originate from the contribution of valance electron numbers of Ti s, Ti p, Ti d, N s and N p orbits. We can also find that the pressure makes that the total DOS decrease at the Fermi level for Ti2N. The bonding behavior of N-Ti compounds is a combination of covalent and ionic nature. As N content increases, valence band broadens, valence electron concentration increases, and covalent interactions become stronger

Comparing CT perfusion with oxygen partial pressure in a rabbit VX2 soft-tissue tumor model.

PubMed

Sun, Chang-Jin; Li, Chao; Lv, Hai-Bo; Zhao, Cong; Yu, Jin-Ming; Wang, Guang-Hui; Luo, Yun-Xiu; Li, Yan; Xiao, Mingyong; Yin, Jun; Lang, Jin-Yi

2014-01-01

The aim of this study was to evaluate the oxygen partial pressure of the rabbit model of the VX2 tumor using a 64-slice perfusion CT and to compare the results with that obtained using the oxygen microelectrode method. Perfusion CT was performed for 45 successfully constructed rabbit models of a VX2 brain tumor. The perfusion values of the brain tumor region of interest, the blood volume (BV), the time to peak (TTP) and the peak enhancement intensity (PEI) were measured. The results were compared with the partial pressure of oxygen (PO2) of that region of interest obtained using the oxygen microelectrode method. The perfusion values of the brain tumor region of interest in 45 successfully constructed rabbit models of a VX2 brain tumor ranged from 1.3-127.0 (average, 21.1 ± 26.7 ml/min/ml); BV ranged from 1.2-53.5 ml/100g (average, 22.2 ± 13.7 ml/100g); PEI ranged from 8.7-124.6 HU (average, 43.5 ± 28.7 HU); and TTP ranged from 8.2-62.3 s (average, 38.8 ± 14.8 s). The PO2 in the corresponding region ranged from 0.14-47 mmHg (average, 16 ± 14.8 mmHg). The perfusion CT positively correlated with the tumor PO2, which can be used for evaluating the tumor hypoxia in clinical practice.

Effect of oxygen partial pressure on oxidation of Mo-metal

NASA Astrophysics Data System (ADS)

Sharma, Rabindar Kumar; Kumar, Prabhat; Singh, Megha; Gopal, Pawar; Reddy, G. B.

2018-05-01

This report explains the effect of oxygen partial pressure (PO2 ) on oxidation of Mo-metal in oxygen plasma. XRD results indulge that oxide layers formed on Mo-surfaces at different oxygen partial pressures have two different oxide phases (i.e. orthorhombic MoO3 and monoclinic Mo8O23). Intense XRD peaks at high pressure (i.e. 2.0×10-1 Torr) points out the formation of thick oxide layer on Mo-surface due to presence of large oxygen species in chamber and less oxide volatilization. Whereas, at low PO2 (6.5×10-2 and 7.5×10-2 Torr.) the reduced peak strength is owing to high oxide volatilization rate. SEM micrographs and thickness measurements also support XRD results and confirm that the optimum -2value of PO2 to deposited thicker and uniform oxide film on glass substrate is 7.5×10-2 Torr through plasma assistedoxidation process. Further to study the compositional properties, EDX of the sample M2 (the best sample) is carried out, which confirms that the stoichiometric ratio is less than 3 (i.e. 2.88). Less stoichiometric ratio again confirms the presence of sub oxides in oxide layers on Mo metal as evidenced by XRD results. All the observed results are well in consonance with each other.

Plateau Waves of Intracranial Pressure and Partial Pressure of Cerebral Oxygen.

PubMed

Lang, Erhard W; Kasprowicz, Magdalena; Smielewski, Peter; Pickard, John; Czosnyka, Marek

2016-01-01

This study investigates 55 intracranial pressure (ICP) plateau waves recorded in 20 patients after severe traumatic brain injury (TBI) with a focus on a moving correlation coefficient between mean arterial pressure (ABP) and ICP, called PRx, which serves as a marker of cerebrovascular reactivity, and a moving correlation coefficient between ABP and cerebral partial pressure of oxygen (pbtO2), called ORx, which serves as a marker for cerebral oxygen reactivity. ICP and ICPamplitude increased significantly during the plateau waves, whereas CPP and pbtO2 decreased significantly. ABP, ABP amplitude, and heart rate remained unchanged. In 73 % of plateau waves PRx increased during the wave. ORx showed an increase during and a decrease after the plateau waves, which was not statistically significant. Our data show profound cerebral vasoparalysis on top of the wave and, to a lesser extent, impairment of cerebral oxygen reactivity. The different behavior of the indices may be due to the different latencies of the cerebral blood flow and oxygen level control mechanisms. While cerebrovascular reactivity is a rapidly reacting mechanism, cerebral oxygen reactivity is slower.

Global Autocorrelation Scales of the Partial Pressure of Oceanic CO2

NASA Technical Reports Server (NTRS)

Li, Zhen; Adamec, David; Takahashi, Taro; Sutherland, Stewart C.

2004-01-01

A global database of approximately 1.7 million observations of the partial pressure of carbon dioxide in surface ocean waters (pCO2) collected between 1970 and 2003 is used to estimate its spatial autocorrelation structure. The patterns of the lag distance where the autocorrelation exceeds 0.8 is similar to patterns in the spatial distribution of the first baroclinic Rossby radius of deformation indicating that ocean circulation processes play a significant role in determining the spatial variability of pCO2. For example, the global maximum of the distance at which autocorrelations exceed 0.8 averages about 140 km in the equatorial Pacific. Also, the lag distance at which the autocorrelation exceed 0.8 is greater in the vicinity of the Gulf Stream than it is near the Kuroshio, approximately 50 km near the Gulf Stream as opposed to 20 km near the Kuroshio. Separate calculations for times when the sun is north and south of the equator revealed no obvious seasonal dependence of the spatial autocorrelation scales. The pCO2 measurements at Ocean Weather Station (OWS) 'P', in the eastern subarctic Pacific (50 N, 145 W) is the only fixed location where an uninterrupted time series of sufficient length exists to calculate a meaningful temporal autocorrelation function for lags greater than a few days. The estimated temporal autocorrelation function at OWS 'P', is highly variable. A spectral analysis of the longest four pCO2 time series indicates a high level of variability occurring over periods from the atmospheric synoptic to the maximum length of the time series, in this case 42 days. It is likely that a relative peak in variability with a period of 3-6 days is related to atmospheric synoptic period variability and ocean mixing events due to wind stirring. However, the short length of available time series makes identifying temporal relationships between pCO2 and atmospheric or ocean processes problematic.

High pressure solubility of carbon dioxide (CO2) in aqueous solution of piperazine (PZ) activated N-methyldiethanolamine (MDEA) solvent for CO2 capture

NASA Astrophysics Data System (ADS)

Khan, Saleem Nawaz; Hailegiorgis, Sintayehu Mekuria; Man, Zakaria; Shariff, Azmi Mohd

2017-10-01

In this study, the solubility of carbon dioxide (CO2) in the aqueous solution of piperazine (PZ) activated N-methyldiethanolamine (MDEA) was investigated. In the aqueous solution the concentrations of the N-methyldiethanolamine (MDEA) and piperazine (PZ) were kept constant at 30 wt. % and 3 wt. %, respectively. The solubility experiments were carried out between the temperatures ranges of 303.15 to 333.15 K. The pressure range was selected as 2-50 bar for solubility of carbon dioxide in the aqueous solution. The solubility of the CO2 is reported in terms of CO2 loading capacity of the solvent. The loading capacity of the solvent is the ratio between the numbers of moles of CO2 absorbed to the numbers of moles of solvent used. The experimental data showed that the CO2 loading increased with increase in CO2 partial pressure, while it decreased with increase in system's temperature. It was also observed from the experimental data that the higher pressure favors the absorption process while the increased temperature hinders the absorption process of CO2 capture. The loading capacity of the investigated solvent was compared with the loading capacity of the solvents reported in the literature. The investigated solvent showed better solubility in terms of loading capacity.

Oxygen-Partial-Pressure Sensor for Aircraft Oxygen Mask

NASA Technical Reports Server (NTRS)

Kelly, Mark; Pettit, Donald

2003-01-01

A device that generates an alarm when the partial pressure of oxygen decreases to less than a preset level has been developed to help prevent hypoxia in a pilot or other crewmember of a military or other high-performance aircraft. Loss of oxygen partial pressure can be caused by poor fit of the mask or failure of a hose or other component of an oxygen distribution system. The deleterious physical and mental effects of hypoxia cause the loss of a military aircraft and crew every few years. The device is installed in the crewmember s oxygen mask and is powered via communication wiring already present in all such oxygen masks. The device (see figure) includes an electrochemical sensor, the output potential of which is proportional to the partial pressure of oxygen. The output of the sensor is amplified and fed to the input of a comparator circuit. A reference potential that corresponds to the amplified sensor output at the alarm oxygen-partial-pressure level is fed to the second input of the comparator. When the sensed partial pressure of oxygen falls below the minimum acceptable level, the output of the comparator goes from the low state (a few millivolts) to the high state (near the supply potential, which is typically 6.8 V for microphone power). The switching of the comparator output to the high state triggers a tactile alarm in the form of a vibration in the mask, generated by a small 1.3-Vdc pager motor spinning an eccentric mass at a rate between 8,000 and 10,000 rpm. The sensation of the mask vibrating against the crewmember s nose is very effective at alerting the crewmember, who may already be groggy from hypoxia and is immersed in an environment that is saturated with visual cues and sounds. Indeed, the sensation is one of rudeness, but such rudeness could be what is needed to stimulate the crewmember to take corrective action in a life-threatening situation.

N2 and P3 modulation during partial inhibition in a modified go/nogo task.

PubMed

Nguyen, An T; Moyle, Jonson J; Fox, Allison M

2016-09-01

The neural response following the partial inhibition of responses can provide insight into the processes underlying response inhibition. We examined the N2 and P3 on trials where participants correctly responded to go stimuli, successfully inhibited their response to nogo stimuli, and nogo trials where they initiated but did not complete their response (partial inhibitions) in an adult sample (N=24, M(age)=21.17, SD(age)=3.52). An enhanced and delayed N2 was observed on partially inhibited compared to successfully inhibited nogo trials. Further analysis showed that this modulation was error-related. An enhanced central P3 was observed following successful inhibitions compared to correct go trials, but not following partial inhibitions. The results suggest that the central P3 enhancement is specific to the complete and successful inhibition of responses. Therefore, the absence of a central P3 on partial inhibitions could reflect insufficient inhibition or a monitored failure in inhibiting the response. Although, our findings provide support for the role of P3 in response inhibition, it raises questions about the processes involved in the subsequent inhibition or correction of the erroneous response. Further research examining the neural response following both partial and unsuccessful inhibitions could provide insight regarding these processes. Copyright © 2016 Elsevier B.V. All rights reserved.

Photosynthesis and growth response of almond to increased atmospheric ozone partial pressures

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

Retzlaff, W.A.; Williams, L.E.; DeJong, T.M.

Uniform nursery stock of five almond cultivars [Prunus dulcis (Mill) D.A. Webb syn. P. amygdalus Batsch, cv. Butte, Carmel, Mission, Nonpareil, and Sonora] propagated on peach (P. domstica L. Batsch.) rootstock were exposed to three different atmospheric ozone (O[sub 3]) partial pressures. The trees were planted in open-top fumigation chambers on 19 Apr. 1989 at the University of California Kearny Agricultural Center located in the San Joaquin Valley of California. Exposures of the trees to three atmospheric O[sub 3] partial pressures lasted from 1 June to 2 Nov. 1989. The mean 12-h [0800-2000 h Pacific Daylight Time (PDT)] O[sub 3]more » partial pressures measured in the open-top chambers during the experimental period were 0.038, 0.060, and 0.112 [mu]Pa Pa[sup [minus]1] O[sub 3] in the charcoal filtered, ambient, and ambient + O[sub 3] treatments, respectively. Leaf net CO[sub 2] assimilation, trunk cross-sectional area growth, and root, trunk, foliage, and total dry weight of Nonpareil were reduced by increased atmospheric O[sub 3] partial pressures. Mission was unaffected by O[sub 3] and Butte, Carmel, and Sonora were intermediate in their responses. Foliage of Nonpareil also abscised prematurely in the ambient and ambient + O[sub 3] treatments. The results indicate that there are almond cultivars that are sensitive to O[sub 3] exposure.« less

Feasibility of measuring dissolved carbon dioxide based on head space partial pressures

USGS Publications Warehouse

Watten, B.J.; Boyd, C.E.; Schwartz, M.F.; Summerfelt, S.T.; Brazil, B.L.

2004-01-01

We describe an instrument prototype that measures dissolved carbon dioxide (DC) without need for standard wetted probe membranes or titration. DC is calculated using Henry's Law, water temperature, and the steady-state partial pressure of carbon dioxide that develops within the instrument's vertical gas-liquid contacting chamber. Gas-phase partial pressures were determined with either an infrared detector (ID) or by measuring voltage developed by a pH electrode immersed in an isolated sodium carbonate solution (SC) sparged with recirculated head space gas. Calculated DC concentrations were compared with those obtained by titration over a range of DC (2, 4, 8, 12, 16, 20, 24, and 28mg/l), total alkalinity (35, 120, and 250mg/l as CaCO3), total dissolved gas pressure (-178 to 120 mmHg), and dissolved oxygen concentrations (7, 14, and 18 mg/l). Statistically significant (P < 0.001) correlations were established between head space (ID) and titrimetrically determined DC concentrations (R2 = 0.987-0.999, N = 96). Millivolt and titrimetric values from the SC solution tests were also correlated (P < 0.001, R 2 = 0.997, N = 16). The absolute and relative error associated with the use of the ID and SC solution averaged 0.9mg/l DC and 7.0% and 0.6 mg/l DC and 9.6%, respectively. The precision of DC estimates established in a second test series was good; coefficients of variation (100(SD/mean)) for the head space (ID) and titration analyses were 0.99% and 1.7%. Precision of the SC solution method was 1.3%. In a third test series, a single ID was coupled with four replicate head space units so as to permit sequential monitoring (15 min intervals) of a common water source. Here, appropriate gas samples were secured using a series of solenoid valves (1.6 mm bore) activated by a time-based controller. This system configuration reduced the capital cost per sample site from US$ 2695 to 876. Absolute error averaged 2.9, 3.1, 3.7, and 2.7 mg/ l for replicates 1-4 (N = 36) during a 21

[Effect of oxygen tubing connection site on percutaneous oxygen partial pressure and percutaneous carbon dioxide partial pressure in patients with chronic obstructive pulmonary disease during noninvasive positive pressure ventilation].

PubMed

Mi, S; Zhang, L M

2017-04-12

Objective: We evaluated the effects of administering oxygen through nasal catheters inside the mask or through the mask on percutaneous oxygen partial pressure (PcO(2))and percutaneous carbon dioxide partial pressure (PcCO(2)) during noninvasive positive pressure ventilation (NPPV) to find a better way of administering oxygen, which could increase PcO(2) by increasing the inspired oxygen concentration. Methods: Ten healthy volunteers and 9 patients with chronic obstructive pulmonary disease complicated by type Ⅱ respiratory failure were included in this study. Oxygen was administered through a nasal catheter inside the mask or through the mask (oxygen flow was 3 and 5 L/min) during NPPV. PcO(2) and PcCO(2) were measured to evaluate the effects of administering oxygen through a nasal catheter inside the mask or through the mask, indirectly reflecting the effects of administering oxygen through nasal catheter inside the mask or through the mask on inspired oxygen concentration. Results: Compared to administering oxygen through the mask during NPPV, elevated PcO(2) was measured in administering oxygen through the nasal catheter inside the mask, and the differences were statistically significant ( P <0.05). At the same time, there was no significant change in PcCO(2) ( P >0.05). Conclusion: Administering oxygen through a nasal catheter inside the mask during NPPV increased PcO(2) by increasing the inspired oxygen concentration but did not increase PcCO(2). This method of administering oxygen could conserve oxygen and be suitable for family NPPV. Our results also provided theoretical basis for the development of new masks.

Partial discharge detection and analysis in low pressure environments

NASA Astrophysics Data System (ADS)

Liu, Xin

Typical aerospace vehicles (aircraft and spacecraft) experience a wide range of operating pressures during ascending and returning to earth. Compared to the sea-level atmospheric pressure (760 Torr), the pressure at about 60 km altitude is 2 Torr. The performance of the electric power system components of the aerospace vehicles must remain reliable even under such sub-atmospheric operating conditions. It is well known that the dielectric strength of gaseous insulators, while the electrode arrangement remains unchanged, is pressure dependent. Therefore, characterization of the performance and behavior of the electrical insulation in flight vehicles in low-pressure environments is extremely important. Partial discharge testing is one of the practical methods for evaluating the integrity of electrical insulation in aerospace vehicles. This dissertation describes partial discharge (PD) measurements performed mainly with 60 Hz ac energization in air, argon and helium, for pressures between 2 and 760 Torr. Two main electrode arrangements were used. One was a needle-plane electrode arrangement with a Teflon insulating barrier. The other one was a twisted pair of insulated conductors taken from a standard aircraft wiring harness. The measurement results are presented in terms of typical PD current pulse waveforms and waveform analysis for both main electrode arrangements. The evaluation criteria are the waveform polarity, magnitude, shape, rise time, and phase angle (temporal location) relative to the source voltage. Two-variable histograms and statistical averages of the PD parameters are presented. The PD physical mechanisms are analyzed. For PD pattern recognition, both statistical methods (such as discharge parameter dot pattern representation, discharge parameter phase distribution, statistical operator calculations, and PD fingerprint development) and wavelet transform applications are investigated. The main conclusions of the dissertation include: (1) The PD current

Effects of hydrogen partial pressure on autotrophic growth and product formation of Acetobacterium woodii.

PubMed

Kantzow, Christina; Weuster-Botz, Dirk

2016-08-01

Low aqueous solubility of the gases for autotrophic fermentations (e.g., hydrogen gas) results in low productivities in bioreactors. A frequently suggested approach to overcome mass transfer limitation is to increase the solubility of the limiting gas in the reaction medium by increasing the partial pressure in the gas phase. An increased inlet hydrogen partial pressure of up to 2.1 bar (total pressure of 3.5 bar) was applied for the autotrophic conversion of hydrogen and carbon dioxide with Acetobacterium woodii in a batch-operated stirred-tank bioreactor with continuous gas supply. Compared to the autotrophic batch process with an inlet hydrogen partial pressure of 0.4 bar (total pressure of 1.0 bar) the final acetate concentration after 3.1 days was reduced to 50 % (29.2 g L(-1) compared to 59.3 g L(-1)), but the final formate concentration was increased by a factor of 18 (7.3 g L(-1) compared to 0.4 g L(-1)). Applying recombinant A. woodii strains overexpressing either genes for enzymes in the methyl branch of the Wood-Ljungdahl pathway or the genes phosphotransacetylase and acetate kinase at an inlet hydrogen partial pressure of 1.4 bar reduced the final formate concentration by up to 40 % and increased the final dry cell mass and acetate concentrations compared to the wild type strain. Solely the overexpression of the two genes for ATP regeneration at the end of the Wood-Ljungdahl pathway resulted in an initial switch off of formate production at increased hydrogen partial pressure until the maximum of the hydrogen uptake rate was reached.

The CO2 stimulus for cerebrovascular reactivity: Fixing inspired concentrations vs. targeting end-tidal partial pressures.

PubMed

Fisher, Joseph A

2016-06-01

Cerebrovascular reactivity (CVR) studies have elucidated the physiology and pathophysiology of cerebral blood flow regulation. A non-invasive, high spatial resolution approach uses carbon dioxide (CO2) as the vasoactive stimulus and magnetic resonance techniques to estimate the cerebral blood flow response. CVR is assessed as the ratio response change to stimulus change. Precise control of the stimulus is sought to minimize CVR variability between tests, and show functional differences. Computerized methods targeting end-tidal CO2 partial pressures are precise, but expensive. Simpler, improvised methods that fix the inspired CO2 concentrations have been recommended as less expensive, and so more widely accessible. However, these methods have drawbacks that have not been previously presented by those that advocate their use, or those that employ them in their studies. As one of the developers of a computerized method, I provide my perspective on the trade-offs between these two methods. The main concern is that declaring the precision of fixed inspired concentration of CO2 is misleading: it does not, as implied, translate to precise control of the actual vasoactive stimulus - the arterial partial pressure of CO2 The inherent test-to-test, and therefore subject-to-subject variability, precludes clinical application of findings. Moreover, improvised methods imply widespread duplication of development, assembly time and costs, yet lack uniformity and quality control. A tabular comparison between approaches is provided. © The Author(s) 2016.

Extending helium partial pressure measurement technology to JET DTE2 and ITER.

PubMed

Klepper, C C; Biewer, T M; Kruezi, U; Vartanian, S; Douai, D; Hillis, D L; Marcus, C

2016-11-01

The detection limit for helium (He) partial pressure monitoring via the Penning discharge optical emission diagnostic, mainly used for tokamak divertor effluent gas analysis, is shown here to be possible for He concentrations down to 0.1% in predominantly deuterium effluents. This result from a dedicated laboratory study means that the technique can now be extended to intrinsically (non-injected) He produced as fusion reaction ash in deuterium-tritium experiments. The paper also examines threshold ionization mass spectroscopy as a potential backup to the optical technique, but finds that further development is needed to attain with plasma pulse-relevant response times. Both these studies are presented in the context of continuing development of plasma pulse-resolving, residual gas analysis for the upcoming JET deuterium-tritium campaign (DTE2) and for ITER.

Gd Ba Cu O bulk superconductors fabricated by a seeded infiltration growth technique under reduced oxygen partial pressure

NASA Astrophysics Data System (ADS)

Iida, K.; Babu, N. H.; Shi, Y. H.; Cardwell, D. A.; Murakami, M.

2006-06-01

Single-grain Gd-Ba-Cu-O (GdBCO) bulk superconductors have been grown by a seeded infiltration and growth (SIG) technique under a 1% O2+N2 atmosphere using a generic MgO-doped Nd-Ba-Cu-O (MgO-NdBCO) seed placed on the sample surface at room temperature (the so-called the cold-seeding method). Partial melting of the MgO-NdBCO seeds fabricated in air under notionally identical thermal processing conditions, however, limited the reliability of this bulk GdBCO single-grain process. The observed seed decomposition is attributed to the dependence of the peritectic temperature Tp of MgO-doped Nd1+xBa2-xCu3Oy solid solution (MgO-doped Nd-123ss, where ss indicates solid solution) compounds on both oxygen partial pressure during the melt process and the level of solid solution (x). The peritectic decomposition temperature of MgO-doped Nd-123ss, with x ranging from 0 to 0.5 under p(O2) = 1.00 atm, was observed to remain constant at 1120 °C. Tp was observed to decrease linearly as a function of solid solution level, on the other hand, under oxygen partial pressures of both p(O2) = 0.21 and 0.01 atm. Based on these results, MgO-doped NdBCO seed crystals should be grown under reduced oxygen partial pressure in order to obtain a stable MgO-doped NdBCO seed crystal suitable for cold-seeding processes of large-grain (RE)BCO bulk superconductors (where RE is a rare earth element).

Method and apparatus for monitoring oxygen partial pressure in air masks

NASA Technical Reports Server (NTRS)

Kelly, Mark E. (Inventor); Pettit, Donald R. (Inventor)

2006-01-01

Method and apparatus are disclosed for monitoring an oxygen partial pressure in an air mask and providing a tactile warning to the user. The oxygen partial pressure in the air mask is detected using an electrochemical sensor, the output signal from which is provided to a comparator. The comparator compares the output signal with a preset reference value or range of values representing acceptable oxygen partial pressures. If the output signal is different than the reference value or outside the range of values, the air mask is vibrated by a vibrating motor to alert the user to a potentially hypoxic condition.

Growth of the microalgae Neochloris oleoabundans at high partial oxygen pressures and sub-saturating light intensity.

PubMed

Sousa, Cláudia; de Winter, Lenneke; Janssen, Marcel; Vermuë, Marian H; Wijffels, René H

2012-01-01

The effect of partial oxygen pressure on growth of Neochloris oleoabundans was studied at sub-saturating light intensity in a fully-controlled stirred tank photobioreactor. At the three partial oxygen pressures tested (P(O)₂= 0.24; 0.63; 0.84 bar), the specific growth rate was 1.38; 1.36 and 1.06 day(-1), respectively. An increase of the P(CO)₂from 0.007 to 0.02 bar at P(O₂) of 0.84 bar resulted in an increase in the growth rate from 1.06 to 1.36 day(-1). These results confirm that the reduction of algal growth at high oxygen concentrations at sub-saturating light conditions is mainly caused by competitive inhibition of Rubisco. This negative effect on growth can be overcome by restoring the O(2)/CO(2) ratio by an increase in the partial carbon dioxide pressure. In comparison to general practice (P(O(2)) = 0.42 bar), working at partial O(2) pressure of 0.84 bar could reduce the energy requirement for degassing by a factor of 3-4. Copyright © 2011 Elsevier Ltd. All rights reserved.

Non-invasive multiwavelength photoplethysmography under low partial pressure of oxygen.

PubMed

Fang, Yung Chieh; Tai, Cheng-Chi

2016-08-01

A reduction in partial pressure of oxygen in the environment may be caused by a gain in altitude, which reduces the atmospheric pressure; it may also be caused by the carbon dioxide generated from breathing in an enclosed space. Does inhaling oxygen of lower partial pressure affect the oxygen-carrying function of haemoglobin in vivo? This study uses non-invasive multiwavelength photoplethysmography to measure the effects that inhaling this type of oxygen can have on the plethysmography of the appendages of the body (fingertips). The results indicate that under low partial pressure of oxygen, be it the result of a gain in carbon dioxide concentration or altitude, the change in visible light absorption is the biggest for short wavelengths (approximately 620 or 640 nm) near deoxyhaemoglobin, which has higher absorption coefficient. Moreover, increasing carbon dioxide concentration from 5000 to 10,000 ppm doubly reduces the absorption rate of these short wavelengths.

Collisional Removal of OH (X (sup 2)Pi, nu=7) by O2, N2, CO2, and N2O

NASA Technical Reports Server (NTRS)

Knutsen, Karen; Dyer, Mark J.; Copeland, Richard A.

1996-01-01

Collisional removal rate constants for the OH (X 2PI, nu = 7) radical are measured for the colliders O2, CO2, and N2O, and an upper limit is established for N2. OH(nu = 4) molecules, generated in a microwave discharge flow cell by the reaction of hydrogen atoms with ozone, are excited to v = 7 by the output of a pulsed infrared laser via direct vibrational overtone excitation. The temporal evolution of the P = 7 population is probed as a function of the collider gas partial pressure by a time-delayed pulsed ultraviolet laser. Fluorescence from the B 21 + state is detected in the visible spectral region.

Report on ISS Oxygen Production, Resupply, and Partial Pressure Management

NASA Technical Reports Server (NTRS)

Schaezler, Ryan; Ghariani, Ahmed; Leonard, Daniel; Lehman, Daniel

2011-01-01

The majority of oxygen used on International Space Station (ISS) is for metabolic support and denitrogenation procedures prior to Extra-Vehicular Activities. Oxygen is supplied by various visiting vehicles such as the Progress and Shuttle in addition to oxygen production capability on both the United States On-Orbit Segment (USOS) and Russian Segment (RS). To maintain a habitable atmosphere the oxygen partial pressure is controlled between upper and lower bounds. The full range of the allowable oxygen partial pressure along with the increased ISS cabin volume is utilized as a buffer allowing days to pass between oxygen production or direct addition of oxygen to the atmosphere from reserves. This paper summarizes amount of oxygen supplied and produced from all of the sources and describes past experience of managing oxygen partial pressure along with the range of management options available to the ISS.

High-pressure phase diagrams of liquid CO2 and N2

NASA Astrophysics Data System (ADS)

Boates, Brian; Bonev, Stanimir

2011-06-01

The phase diagrams of liquid CO2 and N2 have been investigated using first-principles theory. Both materials exhibit transitions to conducting liquids at high temperatures (T) and relatively modest pressures (P). Furthermore, both liquids undergo polymerization phase transitions at pressures comparable to their solid counterparts. The liquid phase diagrams have been divided into several regimes through a detailed analysis of changes in bonding, as well as structural and electronic properties for pressures and temperatures up to 200 GPa and 10 000 K, respectively. Similarities and differences between the high- P and T behavior of these fluids will be discussed. Calculations of the Hugoniot are in excellent agreement with available experimental data. Work supported by NSERC, LLNL, and the Killam Trusts. Prepared by LLNL under Contract DE-AC52-07NA27344.

Catalytic performance of V2O5-MoO3/γ-Al2O3 catalysts for partial oxidation of n-hexane1

NASA Astrophysics Data System (ADS)

Mahmoudian, R.; Khodadadi, Z.; Mahdavi, Vahid; Salehi, Mohammed

2016-01-01

In the current study, a series of V2O5-MoO3 catalyst supported on γ-Al2O3 with various V2O5 and MoO3 loadings was prepared by wet impregnation technique. The characterization of prepared catalysts includes BET surface area, powder X-ray diffraction (XRD), and oxygen chemisorptions. The partial oxidation of n-hexane by air over V2O5-MoO3/γ-Al2O3 catalysts was carried out under flow condition in a fixed bed glass reactor. The effect of V2O5 loading, temperature, MoO3 loading, and n-hexane LHSV on the n-hexane conversion and the product selectivity were investigated. The partial oxygenated products of n-hexane oxidation were ethanol, acetic anhydride, acetic acid, and acetaldehyde. The 10% V2O5-1%MoO3/γ-Al2O3 was found in most active and selective catalyst during partial oxidation of n-hexane. The results indicated that by increasing the temperature, the n-hexane conversion increases as well, although the selectivity of the products passes through a maximum by increasing the temperature.

Effects of Oxygen Partial Pressure on the Surface Tension of Liquid Nickel

NASA Technical Reports Server (NTRS)

SanSoucie, Michael P.; Rogers, Jan R.; Gowda, Vijaya Kumar Malahalli Shankare; Rodriguez, Justin; Matson, Douglas M.

2015-01-01

The NASA Marshall Space Flight Center's electrostatic levitation (ESL) laboratory has been recently upgraded with an oxygen partial pressure controller. This system allows the oxygen partial pressure within the vacuum chamber to be measured and controlled, theoretically in the range from 10-36 to 100 bar. The oxygen control system installed in the ESL laboratory's main chamber consists of an oxygen sensor, oxygen pump, and a control unit. The sensor is a potentiometric device that determines the difference in oxygen activity in two gas compartments (inside the chamber and the air outside of the chamber) separated by an electrolyte, which is yttria-stabilized zirconia. The pump utilizes coulometric titration to either add or remove oxygen. The system is controlled by a desktop control unit, which can also be accessed via a computer. The controller performs temperature control for the sensor and pump, PID-based current loop, and a control algorithm. Oxygen partial pressure has been shown to play a significant role in the surface tension of liquid metals. Oxide films or dissolved oxygen may lead to significant changes in surface tension. The effects of oxygen partial pressure on the surface tension of undercooled liquid nickel will be analyzed, and the results will be presented. The surface tension will be measured at several different oxygen partial pressures while the sample is undercooled. Surface tension will be measured using the oscillating drop method. While undercooled, each sample will be oscillated several times consecutively to investigate how the surface tension behaves with time while at a particular oxygen partial pressure.

LIF measurements and chemical kinetic analysis of methylidyne formation in high-pressure counter-flow partially premixed and non-premixed flames

NASA Astrophysics Data System (ADS)

Naik, S. V.; Laurendeau, N. M.

2004-11-01

We report quantitative, spatially resolved, linear laser-induced fluorescence (LIF) measurements of methylidyne concentration ([CH]) in laminar, methane air, counter-flow partially premixed and non-premixed flames using excitation near 431.5 nm in the A X (0,0) band. For partially premixed flames, fuel-side equivalence ratios (ϕB) of 1.45, 1.6 and 2.0 are studied at pressures of 1, 3, 6, 9 and 12 atm. For non-premixed flames, the fuel-side mixture consists of 25% CH4 and 75% N2; measurements are obtained at pressures of 1, 2, 3, 4, 5, 6, 9 and 12 atm. The quantitative CH measurements are compared with predictions from an opposed-flow flame code utilizing two GRI chemical kinetic mechanisms (versions 2.11 and 3.0). LIF measurements of [CH] are corrected for variations in the quenching rate coefficient by using major species concentrations and temperatures generated by the code along with suitable quenching cross sections for CH available from the literature. A pathway analysis provides relative contributions from important elementary reactions to the total amount of CH produced at various pressures. Key reactions controlling peak CH concentrations are also identified by using a sensitivity analysis. For the partially premixed flames, measured CH profiles are reproduced reasonably well by GRI 3.0, although some quantitative disagreement exists at all pressures. Two CH radical peaks are observed for ϕB=1.45 and ϕB=1.6 at pressures above 3 atm. Peak CH concentrations for the non-premixed flames are significantly underpredicted by GRI 3.0. The latter agrees with previously reported NO concentrations, which are also underpredicted in these same high-pressure counter-flow diffusion flames.

Effect of oxygen partial pressure and VO2 content on hexagonal WO3 thin films synthesized by pulsed laser deposition technique

NASA Astrophysics Data System (ADS)

Kaushal, Ajay; Kaur, Davinder

2011-06-01

We report on the effect of oxygen partial pressure and vacuum annealing on structural and optical properties of pulsed laser-deposited nanocrystalline WO3 thin films. XRD results show the hexagonal phase of deposited WO3 thin films. The crystallite size was observed to increase with increase in oxygen partial pressure. Vacuum annealing changed the transparent as-deposited WO3 thin film to deep shade of blue color which increases the optical absorption of the film. The origin of this blue color could be due to the presence of oxygen vacancies associated with tungsten ions in lower oxidation states. In addition, the effects of VO2 content on structural, electrochemical, and optical properties of (WO3)1- x (VO2) x nanocomposite thin films have also been systematically investigated. Cyclic voltammogram exhibits a modification with the appearance of an extra cathodic peak for VO2-WO3 thin film electrode with higher VO2 content ( x ≥ 0.2). Increase of VO2 content in (WO3)1- x (VO2) x films leads to red shift in optical band gap.

[Effects of gap junction blocking on the oxygen partial pressure in acupoints of the bladder meridian].

PubMed

Wang, Qi; Yu, Wei-Chang; Jiang, Hong-Zhi; Chen, Sheng-Li; Zhang, Ming-Min; Kong, E-Sheng; Huang, Guang-Ying

2010-12-01

To explore the relation between gap junction and meridian phenomenon. The oxygen partial pressure in acupoints [see text for formula] and in their corresponding non-acupoints of the Bladder Meridian was observed with the needle-type tissue oxygen tension sensor in the gap junction blocking goats by 1-Heptanol injection and the Connexin 43 (Cx43) gene knockout mice. (1) The oxygen partial pressure in acupoints of Bladder Meridian on goats was higher than that in non-acupoints after 1-Heptanol injection with significant differences between them (both P < 0.01). (2) The oxygen partial pressure in acupoints of Bladder Meridian on goats increased significantly after injecting 1-Heptanol as compare with that either injecting normal saline or injecting nothing with significant differences between them (all P < 0.01). (3) The oxygen partial pressure in acupoints of the Bladder Meridian was significantly higher than that in the non-acupoint controls in Cx43 wild type (WT) mice (all P < 0.01). In Cx43 heterozygote (HT) mice, the oxygen partial pressure between acupoints and non-acupoint controls showed no significant differences (all P > 0.05). (4) In acupoints, the oxygen partial pressure in Cx43 WT mice was significantly higher than that in Cx43 HT mice (all P < 0.05), while in the corresponding non-acupoints, this difference had no statistically significant (all P > 0.05). Gap junction maybe the essential factor in signal transduction of acupuncture.

Measuring Ancient Air Pressure Using Fossilized Cyanobacteria

NASA Astrophysics Data System (ADS)

Silverman, S. N.; Som, S. M.; Gordon, R.; Bebout, B.

2016-12-01

The evolution of Earth's atmosphere has been governed by biological evolution. The dominant air component, nitrogen, has undergone substantial variation over geological time. Today, the partial pressure of nitrogen is 0.79 bar, but this value could have been much higher during early Earth1. The nitrogen partial pressure is postulated to have dropped to a maximum of 0.5 bar before the Great Oxidation Event 2.4 billion years ago, and subsequently recovered to the 0.8 bar value of our modern atmosphere over the next 330 million years2. We are placing constraints on the trajectory of this recovery by investigating how nitrogen partial pressure influences the morphology of a certain species of filamentous cyanobacteria that has been found fossilized in 2 billion year old rocks. These filamentous cyanobacteria convert nitrogen from its dissolved gaseous state (N2) to a biologically useful state (i.e. NH3) when the latter is present at growth-limiting concentrations in their aquatic environment. Such cyanobacteria develop heterocysts (specialized, visually distinct cells), which fix the nitrogen and laterally distribute it to neighboring cells along the one-dimensional filament. We suggest that the distance between heterocysts reflects the nitrogen partial pressure dissolved in water, which is related to atmospheric pN2 by Henry's law. In the laboratory, we are quantifying the relationship between heterocyst distance, variance and covariance to atmospheric pN2 by subjecting cyanobacteria (in media devoid of nitrate) to different partial pressures of N2 at a constant temperature and lighting for the representative species Anabaena variabilis. As far as we know, such experiments have not been previously conducted. This new geobarometer will complement existing methods of quantifying ancient nitrogen partial pressure. 1Goldblatt, Colin, et al. "Nitrogen-enhanced greenhouse warming on early Earth." Nature Geoscience 2 (2009): 891-896. 2Som, S., et al. "Earth's air pressure 2

Fabrication of lead-free piezoelectric Li2CO3-added (Ba,Ca)(Ti,Sn)O3 ceramics under controlled low oxygen partial pressure and their properties

NASA Astrophysics Data System (ADS)

Noritake, Kouta; Sakamoto, Wataru; Yuitoo, Isamu; Takeuchi, Teruaki; Hayashi, Koichiro; Yogo, Toshinobu

2018-02-01

Reduction-resistant lead-free (Ba,Ca)(Ti,Sn)O3 piezoceramics with high piezoelectric constants were fabricated by optimizing the amount of Li2CO3 added. Oxygen partial pressure was controlled during the sintering of (Ba,Ca)(Ti,Sn)O3 ceramics in a reducing atmosphere using H2-CO2 gas. Enhanced grain growth and a high-polarization state after poling treatment were achieved by adding Li2CO3. Optimizing the amount of Li2CO3 added to (Ba0.95Ca0.05)(Ti0.95Sn0.05)O3 ceramics sintered under a low oxygen partial pressure resulted in improved piezoelectric properties while maintaining the high sintered density. The prepared Li2CO3-added ceramic samples had homogeneous microstructures with a uniform dispersion of each major constituent element. However, the residual Li content in the 3 mol % Li2CO3-added (Ba0.95Ca0.05)(Ti0.95Sn0.05)O3 ceramics after sintering was less than 0.3 mol %. Sintered bodies of this ceramic prepared in a CO2 (1.5%)-H2 (0.3%)/Ar reducing atmosphere (PO2 = 10-8 atm at 1350 °C), exhibited sufficient electrical resistivity and a piezoelectric constant (d 33) exceeding 500 pC/N. The piezoelectric properties of this nonreducible ceramic were comparable or superior to those of the same ceramic sintered in air.

Using Dalton's Law of Partial Pressures to Determine the Vapor Pressure of a Volatile Liquid

ERIC Educational Resources Information Center

Hilgeman, Fred R.; Bertrand, Gary; Wilson, Brent

2007-01-01

This experiment, designed for a general chemistry laboratory, illustrates the use of Dalton's law of partial pressures to determine the vapor pressure of a volatile liquid. A predetermined volume of air is injected into a calibrated tube filled with a liquid whose vapor pressure is to be measured. The volume of the liquid displaced is greater than…

Role of partial miscibility on pressure buildup due to constant rate injection of CO2 into closed and open brine aquifers

NASA Astrophysics Data System (ADS)

Mathias, Simon A.; Gluyas, Jon G.; GonzáLez MartíNez de Miguel, Gerardo J.; Hosseini, Seyyed A.

2011-12-01

This work extends an existing analytical solution for pressure buildup because of CO2 injection in brine aquifers by incorporating effects associated with partial miscibility. These include evaporation of water into the CO2 rich phase and dissolution of CO2 into brine and salt precipitation. The resulting equations are closed-form, including the locations of the associated leading and trailing shock fronts. Derivation of the analytical solution involves making a number of simplifying assumptions including: vertical pressure equilibrium, negligible capillary pressure, and constant fluid properties. The analytical solution is compared to results from TOUGH2 and found to accurately approximate the extent of the dry-out zone around the well, the resulting permeability enhancement due to residual brine evaporation, the volumetric saturation of precipitated salt, and the vertically averaged pressure distribution in both space and time for the four scenarios studied. While brine evaporation is found to have a considerable effect on pressure, the effect of CO2 dissolution is found to be small. The resulting equations remain simple to evaluate in spreadsheet software and represent a significant improvement on current methods for estimating pressure-limited CO2 storage capacity.

Turbulent piloted partially-premixed flames with varying levels of O2/N2: stability limits and PDF calculations

NASA Astrophysics Data System (ADS)

Juddoo, Mrinal; Masri, Assaad R.; Pope, Stephen B.

2011-12-01

This paper reports measured stability limits and PDF calculations of piloted, turbulent flames of compressed natural gas (CNG) partially-premixed with either pure oxygen, or with varying levels of O2/N2. Stability limits are presented for flames of CNG fuel premixed with up to 20% oxygen as well as CNG-O2-N2 fuel where the O2 content is varied from 8 to 22% by volume. Calculations are presented for (i) Sydney flame B [Masri et al. 1988] which uses pure CNG as well as flames B15 to B25 where the CNG is partially-premixed with 15-25% oxygen by volume, respectively and (ii) Sandia methane-air (1:3 by volume) flame E [Barlow et al. 2005] as well as new flames E15 and E25 that are partially-premixed with 'reconstituted air' where the O2 content in nitrogen is 15 and 25% by volume, respectively. The calculations solve a transported PDF of composition using a particle-based Monte Carlo method and employ the EMST mixing model as well as detailed chemical kinetics. The addition of oxygen to the fuel increases stability, shortens the flames, broadens the reaction zone, and shifts the stoichiometric mixture fraction towards the inner side of the jet. It is found that for pure CNG flames where the reaction zone is narrow (∼0.1 in mixture fraction space), the PDF calculations fail to reproduce the correct level of local extinction on approach to blow-off. A broadening in the reaction zone up to about 0.25 in mixture fraction space is needed for the PDF/EMST approach to be able to capture these finite-rate chemistry effects. It is also found that for the same level of partial premixing, increasing the O2/N2 ratio increases the maximum levels of CO and NO but shifts the peak to richer mixture fractions. Over the range of oxygenation investigated here, stability limits have shown to improve almost linearly with increasing oxygen levels in the fuel and with increasing the contribution of release rate from the pilot.

Partial pressures of oxygen, phosphorus and fluorine in some lunar lavas

NASA Technical Reports Server (NTRS)

Nash, W. P.; Hausel, W. D.

1973-01-01

Lunar sample 14310 is a feldspar-rich basalt which shows no evidence of shock deformation or recrystallization. Pyroxenes include Mg-rich orthopyroxene, pigeonite and augite; pyroxferroite occurs in the interstitial residuum. Plagioclase feldspars are zoned from An(96) to An(67), and variations in feldspar compositions do not necessarily indicate loss of Na during eruption of the lava. Opaque phases include ilmenite, ulvospinel, metallic iron, troilite, and schreibersite. Both whitlockite and apatite are present, and the interstitial residua contain baddeleyite, tranquillityite and barium-rich sanidine. Theoretical calculations provide estimates of partial pressures of oxygen, phosphorus, and fluorine in lunar magmas. In general, partial pressures of oxygen are restricted by the limiting assemblages of iron-wuestite and ilmenite-iron-rutile; phosphorus partial pressures are higher in lunar magmas than in terrestrial lavas. The occurrence of whitlockite indicates significantly lower fugacities of fluorine in lunar magmas than in terrestrial magmas.

Measurements of Pressure Distributions and Force Coefficients in a Squeeze Film Damper. Part 2: Partially Sealed Configuration

NASA Technical Reports Server (NTRS)

Jung, S. Y.; Sanandres, Luis A.; Vance, J. M.

1991-01-01

Experimental results from a partially sealed squeeze film damper (SFD) test rig, executing a circular centered orbit are presented and discussed. A serrated piston ring is installed at the damper exit. This device involves a new sealing concept which produces high damping values while allowing for oil flow to cool the damper. In the partially sealed damper, large cavitation regions are observed in the pressure fields at orbit radii epsilon equals 0.5 and epsilon equals 0.8. The cavitated pressure distributions and the corresponding force coefficients are compared with a cavitated bearing solution. The experimental results show the significance of fluid inertia and vapor cavitation in the operation of squeeze film dampers. Squeeze film Reynolds numbers tested reach up to Re equals 50, spanning the range of contemporary applications.

[Efficacy observation on application of negative pressure therapy in the treatment of superficial partial-thickness scald wound in children].

PubMed

Shen, Chuan-an; Chai, Jia-ke; Tuo, Xiao-ye; Cai, Jian-hua; Li, Dong-jie; Zhang, Lin; Zhu, Hua; Cai, Jin-dong

2013-02-01

To observe the effect of negative pressure therapy in the treatment of superficial partial-thickness scald in children. Three hundred and seven children with superficial partial-thickness scald hospitalized from August 2009 to May 2012 were divided into negative pressure therapy group (NPT, n = 145) and control group (C, n = 162) according to the random number table. Patients in group NPT were treated with negative pressure from within post injury day (PID) 3 to PID 9 (with -16 kPa pressure), while traditional occlusive dressing method was used in group C. Changes in body temperature, wound healing condition, frequency of dressing change were compared between group NPT and group C. Bacterial culture results of wounds were compared before and after treatment in group NPT. Volume of drained transudate per one percent of wound area was recorded in group NPT on PID 1 to PID 3. Data were processed with t test or chi-square test. The incidence of high fever was significantly lower in group NPT (26.9%, 39/145) than in group C (63.6%, 103/162, χ(2) = 41.419, P < 0.01). On PID 9, complete wound epithelization was observed in 138 patients in group NPT, and in 7 patients there were a few residual wounds which healed after dressing change for 2 days. The wound healing time of patients in group NPT [(9.2 ± 0.6) d] was obviously shorter than that in group C [(10.1 ± 1.6) d, t = 6.895, P < 0.01]. The frequency of dressing change among patients in group NPT [(2.05 ± 0.22) times] was significantly decreased as compared with that in group C [(4.82 ± 0.81) times, t = 39.878, P < 0.01]. Bacteria were found in wound secretion of seventeen patients in group NPT before treatment, while no bacterium was discovered in all patients after treatment. Volumes of drainage fluid in group NPT were proportional to wound areas, which were respectively (9.8 ± 3.2), (6.2 ± 2.1), (4.1 ± 1.6) mL per one percent of wound area on PID 1, 2, and 3. NPT can decrease times of dressing change, and

Annealing temperature and O2 partial pressure dependence of T(sub c) in HgBa2CuO(4+delta)

NASA Technical Reports Server (NTRS)

Xiong, Q.; Cao, Y.; Chen, F.; Xue, Y. Y.; Chu, C. W.

1994-01-01

Samples of HgBa2CuO(4+delta) (Hg-1201) were annealed under various conditions. After carefully controlling annealing time, annealing temperature (T(sub a)) and O2 partial pressure (P(sub 0)), we were able to find the reversible annealing conditions for Hg-1201. Under 1 atm O2 at 260 C less than or equal to T(sub a) less than or equal to 400 C, the obtained T(sub c) is nearly the same (approximately 97 K). However, it decreases quickly with T(sub a) greater than 300 C in high vacuum (P(sub 0) approximately 10(exp -8) atm), and reaches zero at T(sub a) = 400 C. On the other hand, T(sub c) decreases with the decrease of T(sub a) in high-pressure O2 (approximately 500 atm) and reaches approximately 20 K at about 240 C. In the entire annealing region, the oxygen surplus varies significantly from 0.03 to 0.4, and a wide range of T(sub c) variation (0 goes to 97 K goes to 20 K) was obtained with anion doping alone.

Calibration Of Partial-Pressure-Of-Oxygen Sensors

NASA Technical Reports Server (NTRS)

Yount, David W.; Heronimus, Kevin

1995-01-01

Report and analysis of, and discussion of improvements in, procedure for calibrating partial-pressure-of-oxygen sensors to satisfy Spacelab calibration requirements released. Sensors exhibit fast drift, which results in short calibration period not suitable for Spacelab. By assessing complete process of determining total drift range available, calibration procedure modified to eliminate errors and still satisfy requirements without compromising integrity of system.

Influence of oxygen partial pressure on the microstructural and magnetic properties of Er-doped ZnO thin films

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

Chen, Wei-Bin; Li, Fei; Chen, Hong-Ming

2015-06-15

Er-doped ZnO thin films have been prepared by using inductively coupled plasma enhanced physical vapor deposition at different O{sub 2}:Ar gas flow ratio (R = 0:30, 1:30, 1:15, 1:10 and 1:6). The influence of oxygen partial pressure on the structural, optical and magnetic properties was studied. It is found that an appropriate oxygen partial pressure (R=1:10) can produce the best crystalline quality with a maximum grain size. The internal strain, estimated by fitting the X-ray diffraction peaks, varied with oxygen partial pressure during growth. PL measurements show that plenty of defects, especially zinc vacancy, exist in Er-doped ZnO films. Allmore » the samples show room-temperature ferromagnetism. Importantly, the saturation magnetization exhibits similar dependency on oxygen partial pressure with the internal strain, which indicates that internal strain has an important effect on the magnetic properties of Er-doped ZnO thin films.« less

Effect of Partially Fluorinated N-Alkyl-Substituted Piperidine-2-carboxamides on Pharmacologically Relevant Properties.

PubMed

Vorberg, Raffael; Trapp, Nils; Zimmerli, Daniel; Wagner, Björn; Fischer, Holger; Kratochwil, Nicole A; Kansy, Manfred; Carreira, Erick M; Müller, Klaus

2016-10-06

The modulation of pharmacologically relevant properties of N-alkyl-piperidine-2-carboxamides was studied by selective introduction of 1-3 fluorine atoms into the n-propyl and n-butyl side chains of the local anesthetics ropivacaine and levobupivacaine. The basicity modulation by nearby fluorine substituents is essentially additive and exhibits an exponential attenuation as a function of topological distance between fluorine and the basic center. The intrinsic lipophilicity of the neutral piperidine derivatives displays the characteristic response noted for partially fluorinated alkyl groups attached to neutral heteroaryl systems. However, basicity decrease by nearby fluorine substituents affects lipophilicities at neutral pH, so that all partially fluorinated derivatives are of similar or higher lipophilicity than their non-fluorinated parents. Aqueous solubilities were found to correlate inversely with lipophilicity with a significant contribution from crystal packing energies, as indicated by variations in melting point temperatures. All fluorinated derivatives were found to be somewhat more readily oxidized in human liver microsomes, the rates of degradation correlating with increasing lipophilicity. Because the piperidine-2-carboxamide core is chiral, pairs with enantiomeric N-alkyl groups are diastereomeric. While little response to such stereoisomerism was observed for basicity or lipophilicity, more pronounced variations were observed for melting point temperatures and oxidative degradation. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Measured pressure distributions inside nonaxisymmetric nozzles with partially deployed thrust reversers

NASA Technical Reports Server (NTRS)

Green, Robert S.; Carson, George T., Jr.

1987-01-01

An investigation was conducted in the Langley 16-Foot Transonic Tunnel at static conditions to measure the pressure distributions inside a nonaxisymmetric nozzle with simultaneous partial thrust reversing (50-percent deployment) and thrust vectoring of the primary (forward-thrust) nozzle flow. Geometric forward-thrust-vector angles of 0 and 15 deg. were tested. Test data were obtained at static conditions while nozzle pressure ratio was varied from 2.0 to 4.0. Results indicate that, unlike the 0 deg. vector angle nozzle, a complicated, asymmetric exhaust flow pattern exists in the primary-flow exhaust duct of the 15 deg. vectored nozzle.

Oxygen partial pressure influence on the character of InGaZnO thin films grown by PLD

NASA Astrophysics Data System (ADS)

Lu, Yi; Wang, Li

2012-11-01

The amorphous oxide semiconductors (AOSs) are promising for emerging large-area optoelectronic applications because of capability of large-area, uniform deposition at low temperatures such as room temperature (RT). Indium-gallium-zinc oxide (InGaZnO) thin film is a promising amorphous semiconductors material in thin film transistors (TFT) for its excellent electrical properties. In our work, the InGaZnO thin films are fabricated on the SiO2 glass using pulsed laser deposition (PLD) in the oxygen partial pressure altered from 1 to 10 Pa at RT. The targets were prepared by mixing Ga2O3, In2O3, and ZnO powder at a mol ratio of 1: 7: 2 before the solid-state reactions in a tube furnace at the atmospheric pressure. The targets were irradiated by an Nd:YAG laser(355nm). Finally, we have three films of 270nm, 230nm, 190nm thick for 1Pa, 5Pa, 10Pa oxygen partial pressure. The product thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), Hall-effect investigation. The comparative study demonstrated the character changes of the structure and electronic transport properties, which is probably occurred as a fact of the different oxygen partial pressure used in the PLD.

Three distinct modes in a surface micro-discharge in atmospheric pressure He + N{sub 2} mixtures

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

Li, Dong; Liu, Dingxin, E-mail: liudingxin@mail.xjtu.edu.cn; He, Tongtong

2015-12-15

A surface micro-discharge in atmospheric pressure He + N{sub 2} mixtures is studied in this paper with an emphasis on the discharge modes. With the N{sub 2} admixture increasing from 0.1% to 20%, the discharge evolves from a spatially diffuse mode to a filamentary mode during positive half-cycles of the applied voltage. However during the negative half-cycles, an additional patterned mode emerges between the diffuse and the filamentary modes, which has not been reported before to exist in surface micro-discharges. In the diffuse and patterned modes, the plasmas cover almost the entirety of the mesh area during one cycle after plasma ignitionmore » in all mesh elements, and the discharge power increases linearly with the applied voltage. In contrast, plasma coverage of the mesh area is only partial in the filamentary mode and the plasma is more unstable with the discharge power increasing exponentially with the applied voltage. As the surface micro-discharge evolves through the three modes, the density of excited species changes significantly, for instance, the density of N{sub 2}{sup +}(B) drops by ∼20-fold from [N{sub 2}] = 0.2% to 20%. The N{sub 2}{sup +}(B) is predicted to be generated mainly through successive processes of Penning ionization by helium metastables and electron-impact excitation of N{sub 2}{sup +}(X), the latter is most responsible for the density decrease of N{sub 2}{sup +}(B) because much more N{sub 2}{sup +}(X) is converted to N{sub 4}{sup +}(X) as the increase of N{sub 2} fraction. Also, the electron density and electron temperature decrease with the discharge mode transition.« less

High rate reactive sputtering of MoN(x) coatings

NASA Technical Reports Server (NTRS)

Rudnik, Paul J.; Graham, Michael E.; Sproul, William D.

1991-01-01

High rate reactive sputtering of MoN(x) films was performed using feedback control of the nitorgen partial pressure. Coatings were made at four different target powers: 2.5, 5.0, 7.5 and 10 kW. No hysteresis was observed in the nitrogen partial pressure vs. flow plot, as is typically seen for the Ti-N system. Four phases were determined by X-ray diffraction: molybdenum, Mo-N solid solution, Beta-Mo2N and gamma-Mo2N. The hardness of the coatings depended upon composition, substrate bias, and target power. The phases present in the hardest films differed depending upon deposition parameters. For example, the Beta-Mo2N phase was hardest (load 25 gf) at 5.0 kW with a value of 3200 kgf/sq mm, whereas the hardest coatings at 10 kW were the gamma-Mo2N phase (3000 kgf/sq mm). The deposition rate generally decreased with increasing nitrogen partial pressure, but there was a range of partial pressures where the rate was relatively constant. At a target power of 5.0 kW, for example, the deposition rates were 3300 A/min for a N2 partial pressure of 0.05 - 1.0 mTorr.

Measurement and Control of Oxygen Partial Pressure in an Electrostatic Levitator

NASA Technical Reports Server (NTRS)

SanSoucie, Michael P.; Rogers, Jan R.

2014-01-01

Recently the NASA Marshall Space Flight Center electrostatic levitation (ESL) laboratory has been upgraded to include an oxygen control system. This system allows the oxygen partial pressure within the vacuum chamber to be measured and controlled, at elevated temperatures, theoretically in the range from 10(exp -36) to 10(exp 0) bar. The role of active surface agents in liquid metals is fairly well known; however, published surface tension data typically has large scatter, which has been hypothesized to be caused by the presence of oxygen. The surface tension of metals is affected by even a small amount of adsorption of oxygen. It has even been shown that oxygen partial pressures may need to be as low as 10(exp -24) bar to avoid oxidation. While electrostatic levitation is done under high vacuum, oxide films or dissolved oxygen may have significant effects on materials properties, such as surface tension and viscosity. Therefore, the ability to measure and control the oxygen partial pressure within the chamber is highly desirable. The oxygen control system installed at MSFC contains a potentiometric sensor, which measures the oxygen partial pressure, and an oxygen ion pump. In the pump, a pulse-width modulated electric current is applied to yttrium-stabilized zirconia, resulting in oxygen transfer into or out of the system. Also part of the system is a control unit, which consists of temperature controllers for the sensor and pump, PID-based current loop for the ion pump, and a control algorithm. This system can be used to study the effects of oxygen on the thermophysical properties of metals, ceramics, glasses, and alloys. It can also be used to provide more accurate measurements by processing the samples at very low oxygen partial pressures. The oxygen control system will be explained in more detail and an overview of its use and limitations in an electrostatic levitator will be described. Some preliminary measurements have been made, and the results to date will

Role of low O 2 pressure and growth temperature on electrical transport of PLD grown ZnO thin films on Si substrates

NASA Astrophysics Data System (ADS)

Pandis, Ch.; Brilis, N.; Tsamakis, D.; Ali, H. A.; Krishnamoorthy, S.; Iliadis, A. A.

2006-06-01

Undoped ZnO thin films have been grown on (100) Si substrates by pulsed laser deposition. The effect of growth parameters such as temperature, O 2 partial pressure and laser fluence on the structural and electrical properties of the films has been investigated. It is shown that the well-known native n-type conductivity, attributed to the activation of hydrogenic donor states, exhibits a conversion from n-type to p-type when the O 2 partial pressure is reduced from 10 -4 to 10 -7 Torr at growth temperatures lower than 400 °C. The p-type conductivity could be attributed to the dominant role of the acceptor Zn vacancies for ZnO films grown at very low O 2 pressures.

Phase development in the Bi 2Sr 2CaCu 2O y system . Effects of oxygen pressure

NASA Astrophysics Data System (ADS)

List, F. A.; Hsu, H.; Cavin, O. B.; Porter, W. D.; Hubbard, C. R.; Kroeger, D. M.

1992-11-01

Studies have been undertaken using thermal analysis, in conjunction with high-temperature and room temperature X-ray diffraction, fraction, to elucidate phase relationships during thermal processing of thick films of initially phase pure Bi 2Sr 2CaCu 2O y (2212) on silver substrates in various oxygen-containing atmospheres (0.001 to 100% O 2). Exothermic events on cooling at 10°C/min from a partially liquid state vary with oxygen partial pressure and can be grouped into three sets (I-III). Set I is prominent for 0.001% and 0.1% O 2 in the range of 740-775°C and is believed to be associated with the crystallization of a Cu-free ∼ Bi 5Sr 3Ca 1 oxide phase. Set II results from the crystallization of 2212; it is observed for p(O 2)≥1.0% in the temperature range 800-870°C. Set III appears for 21% and 100% O 2 in the temperature range 880-910°C, and its origin is not clear from the results of this study. Subsequent room temperature X-ray diffraction from these samples suggests that in general high oxygen partial pressures (100% O 2) tend to favor the formation of Bi 2Sr 2CuO 6 (2201), whereas low oxygen partial pressures (0.001-0.1% O 2) lead to the formation of a Cu-free, Bi-Sr-Ca oxide phase. The 2212 phase forms at this cooling rate predominantly for intermediate oxygen partial pressures (7.6-21% O 2). High-temperature X-ray diffraction during cooling (2°C/h) from the partially liquid state shows a pronounced dependence of the order of evolution of crystalline 2212 and 2201 phases on p(O 2). For an oxygen partial pressure of 1.0% the formation of 2212 precedes that of 2201, whereas for 0.01% O 2 2201 crystallizes at a higher temperature than 2212. The implications of these results pertaining to thermal processing of thick 2212 films are discussed.

Reversible effects of oxygen partial pressure on genes associated with placental angiogenesis and differentiation in primary-term cytotrophoblast cell culture.

PubMed

Debiève, F; Depoix, C; Gruson, D; Hubinont, C

2013-09-01

Timely regulated changes in oxygen partial pressure are important for placental formation. Disturbances could be responsible for pregnancy-related diseases like preeclampsia and intrauterine growth restriction. We aimed to (i) determine the effect of oxygen partial pressure on cytotrophoblast differentiation; (ii) measure mRNA expression and protein secretion from genes associated with placental angiogenesis; and (iii) determine the reversibility of these effects at different oxygen partial pressures. Term cytotrophoblasts were incubated at 21% and 2.5% O2 for 96 hr, or were switched between the two oxygen concentrations after 48 hr. Real-time PCR and enzyme-linked immunosorbent assays (ELISAs) were used to evaluate cell fusion and differentiation, measuring transcript levels for those genes involved in cell fusion and placental angiogenesis, including VEGF, PlGF, VEGFR1, sVEGFR1, sENG, INHA, and GCM1. Cytotrophoblasts underwent fusion and differentiation in 2.5% O2 . PlGF expression was inhibited while sVEGFR1 expression increased. VEGF and sENG mRNA expressions increased in 2.5% compared to 21% O2 , but no protein was detected in the cell supernatants. Finally, GCM1 mRNA expression increased during trophoblast differentiation at 21% O2 , but was inhibited at 2.5% O2 . These mRNA expression effects were reversed by returning the cells to 21% O2 . Thus, low-oxygen partial pressure does not inhibit term-cytotrophoblast cell fusion and differentiation in vitro. Lowering the oxygen partial pressure from 21% to 2.5% caused normal-term trophoblasts to reversibly modify their expression of genes associated with placental angiogenesis. This suggests that modifications observed in pregnancy diseases such as preeclampsia or growth retardation are probably due to an extrinsic effect on trophoblasts. Copyright © 2013 Wiley Periodicals, Inc.

High pressure synthesis and magnetic studies of quasi one dimensional systems Sr(n-1)Cu(n+1)O(2n) (n=3,5)

NASA Technical Reports Server (NTRS)

Azuma, M.; Hiroi, Z.; Takano, M.; Ishida, K.; Kitaoka, Y.

1995-01-01

SrCu2O3 and Sr2Cu3O5 containing two-leg and three-leg S = 1/2 ladders made of antiferromagnetic Cu-O-Cu linear bonds, respectively, were synthesized at high pressure, and their crystallographic and magnetic properties were investigated. Both susceptibility and T(1) data of NMR (nuclear magnetic resonance) revealed the existence of a large spin gap only for SrCu2O3. Superconductivity, which had been predicted theoretically for carrier-doped SrCu2O3 could not be realized although partial substitution of La(3+) for Sr(2+) seemed to be carried out successfully. Electron carriers injected seems to remain localized.

Modeling the exhumation path of partially melted ultrahigh-pressure metapelites, North-East Greenland Caledonides

NASA Astrophysics Data System (ADS)

Lang, Helen M.; Gilotti, Jane A.

2015-06-01

Pseudosection modeling constrains the pressure-temperature (P-T) exhumation path of partially melted ultrahigh-pressure (UHP) metapelites exposed in the North-East Greenland UHP terrane. A robust peak P and T estimate of 3.6 GPa and 970 °C based on mineral assemblages in nearby kyanite eclogites is the starting point for the P-T path. Although the peak assemblage for the metapelite is not preserved, the calculated modeled peak assemblage contained substantial clinopyroxene, garnet, phengite, K-feldspar and coesite with minor kyanite and rutile. Combining the pseudosection and observed textures, the decompression path crosses the coesite-quartz transition before reaching the dry phengite dehydration melting reaction where phengite is abruptly consumed. In the range of 2.5 to 2.2 GPa, clinopyroxene is completely consumed and garnet grows to its maximum volume and grossular content, matching the high grossular rims of relict megacrysts. Plagioclase joins the assemblage and the pseudosection predicts up to 12-13 vol.% melt in the supersolidus assemblage, which contained garnet, liquid, K-feldspar, plagioclase, kyanite, quartz and rutile. At this stage, the steep decompression path flattened out and became nearly isobaric. The melt crystallization assemblage that formed when the path crossed the solidus with decreasing temperature contains phengite, garnet, biotite, 2 feldspars, kyanite, quartz and rutile. Therefore, the path must have intersected the solidus at approximately 1.2 GPa, 825 °C. The pseudosection predicts that garnet is consumed on the cooling path, but little evidence of late garnet consumption or other retrograde effects is observed. This may be due to partial melt loss from the rock. Isochemical PT-n and PT-X sections calculated along the P-T path display changes in mineral assemblage and composition that are consistent with preserved assemblages.

N2 pressure - broadened O3 line widths and strengths near 1129.4 cm-1

NASA Technical Reports Server (NTRS)

Copeland, G. E.; Majorana, L. N.; Harward, C. N.; Steinkamp, R. J.

1982-01-01

A Beer's Law experiment was performed with a tunable diode laser to find the N2 pressure broadening characteristics of a single 03 absorption line at 1129.426 cm for N2 pressures from 10 to 100 torr (O3 pressure = 3.16 torr). SO2 line positions were used for wavelength calibration. Line shapes were interatively fitted to a Lorentz function. Results were delta (HWHM in MHz) = 47.44 (+ or - 5.34) MHz + 1.730 (+ or - 0.088) MHz/torr *p(torr) with sigma = 0.9897. This intercept compares well with the Doppler O3 - O3 broadened (at 3.16 torr) width of 44.52 Hz. This result in a HWHM line width of 0.44 cm atm at 760 torr and 285 K. The line strengths integrated over delta nu = 0.55 cm were found to be N2 pressure dependent.

[Correlation between the inspired fraction of oxygen, maternal partial oxygen pressure, and fetal partial oxygen pressure during cesarean section of normal pregnancies].

PubMed

Castro, Carlos Henrique Viana de; Cruvinel, Marcos Guilherme Cunha; Carneiro, Fabiano Soares; Silva, Yerkes Pereira; Cabral, Antônio Carlos Vieira; Bessa, Roberto Cardoso

2009-01-01

Despite changes in pulmonary function, maternal oxygenation is maintained during obstetric regional blocks. But in those situations, the administration of supplementary oxygen to parturients is a common practice. Good fetal oxygenation is the main justification; however, this has not been proven. The objective of this randomized, prospective study was to test the hypothesis of whether maternal hyperoxia is correlated with an increase in fetal gasometric parameters in elective cesarean sections. Arterial blood gases of 20 parturients undergoing spinal block with different inspired fractions of oxygen were evaluated and correlated with fetal arterial blood gases. An increase in maternal inspired fraction of oxygen did not show any correlation with an increase of fetal partial oxygen pressure. Induction of maternal hyperoxia by the administration of supplementary oxygen did not increase fetal partial oxygen pressure. Fetal gasometric parameters did not change even when maternal parameters changed, induced by hyperoxia, during cesarean section under spinal block.

Effect of substrate temperature and oxygen partial pressure on RF sputtered NiO thin films

NASA Astrophysics Data System (ADS)

Cheemadan, Saheer; Santhosh Kumar, M. C.

2018-04-01

Nickel oxide (NiO) thin films were deposited by RF sputtering process and the physical properties were investigated for varying substrate temperatures and oxygen partial pressure. The variation of the crystallographic orientation and microstructure of the NiO thin films with an increase in substrate temperature were studied. It was observed that NiO thin films deposited at 350 °C shows relatively good crystalline characteristics with a preferential orientation along (111) plane. With the optimum substrate temperature of 350 °C, the NiO thin films were deposited under various oxygen partial pressures at the same experimental conditions. The structural, optical and electrical properties of NiO thin films under varying oxygen partial pressure of 10%–50% were investigated. From XRD it is clear that the films prepared in the pure argon atmosphere were amorphous while the films in oxygen partial pressure exhibited polycrystalline NiO phase. SEM and AFM investigations unveil that the higher substrate temperature improves the microstructure of the thin films. It is revealed that the NiO thin films deposited at oxygen partial pressure of 40% and a substrate temperature of 350 °C, showed higher electrical conductivity with p-type characteristics.

Effects of hydrostatic pressure and biaxial strains on the elastic and electronic properties of t-C8B2N2

NASA Astrophysics Data System (ADS)

Zhu, Haiyan; Shi, Liwei; Li, Shuaiqi; Duan, Yifeng; Zhang, Shaobo; Xia, Wangsuo

2018-04-01

The effects of hydrostatic pressure and biaxial strains on the elastic and electronic properties of a superhard material t-C8B2N2 have been studied using first-principles calculations. The structure is proven to be mechanically and dynamically stable under the applied external forces. All the elastic constants (except C66) and elastic modulus increase (decrease) with increasing pressure and compressive (tensile) biaxial strain ɛxx. A microscopic model is used to calculate the Vicker's hardness of every single bond as well as the crystal. The hardness of t-C8B2N2 (64.7 GPa) exceeds that of c-BN (62 GPa) and increases obviously by employing pressure and compressive ɛxx. Furthermore, the Debye temperature and anisotropy of sound velocities for t-C8B2N2 have been discussed. t-C8B2N2 undergoes an indirect to direct bandgap transition when ɛxx > 2%; however, the indirect bandgap character of the material remains under pressure.

Solubility of carbon monoxide in n-hexane between 293 and 473 K and CO pressures up to 200 bar

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

Koelliker, R.; Thies, H.

The solubility of carbon monoxide, CO, in n-hexane was measured at 293, 323, 373, 423, and 473 K for CO partial pressures up to 200 bar. The enthalpy of solution was calculated between 293 and 473 K. Using the Krichevsky-Ilinskaya equation of state, the solubility of CO in n-hexane can be calculated between 293 and 423 K for CO partial pressures up to 200 bar with an accuracy better than 5%.

Measurement of partial pressures in vacuum technology and vacuum physics

NASA Technical Reports Server (NTRS)

Huber, W. K.

1986-01-01

It is pointed out that the measurement of gaseous pressures of less than 0.0001 torr is based on the ionization of gas atoms and molecules due to collisions with electrons. The particle density is determined in place of the pressure. The ionization cross sections for molecules of various gases are discussed. It is found that the true pressure in a vacuum system cannot be determined with certainty if it is unknown which gas is present. Effects of partial pressure determination on the condition of the vacuum system are discussed together with ion sources, systems of separation, and ion detection.

Observation of a re-entrant phase transition in the molecular complex tris(μ 2-3,5-diisopropyl-1,2,4-triazolato-κ 2 N 1: N 2)trigold(I) under high pressure

DOE PAGES

Woodall, Christopher H.; Christensen, Jeppe; Skelton, Jonathan M.; ...

2016-08-18

We report a molecular crystal that exhibits four successive phase transitions under hydro­static pressure, driven by aurophilic interactions, with the ground-state structure re-emerging at high pressure. The effect of pressure on two polytypes of tris(μ 2-3,5-diiso­propyl-1,2,4-triazolato-κ 2 N 1: N 2)trigold(I) (denoted Form-I and Form-II) has been analysed using luminescence spectroscopy, single-crystal X-ray diffraction and first-principles computation. A unique phase behaviour was observed in Form-I, with a complex sequence of phase transitions between 1 and 3.5 GPa. The ambient C2/c mother cell transforms to a P2 1/n phase above 1 GPa, followed by a P2 1/a phase above 2 GPamore » and a large-volume C2/c supercell at 2.70 GPa, with the previously observed P2 1/n phase then reappearing at higher pressure. The observation of crystallographically identical low- and high-pressure P2 1/n phases makes this a rare example of a re-entrant phase transformation. The phase behaviour has been characterized using detailed crystallographic theory and modelling, and rationalized in terms of molecular structural distortions. The dramatic changes in conformation are correlated with shifts of the luminescence maxima, from a band maximum at 14040 cm –1 at 2.40 GPa, decreasing steeply to 13550 cm –1 at 3 GPa. A similar study of Form-II displays more conventional crystallographic behaviour, indicating that the complex behaviour observed in Form-I is likely to be a direct consequence of the differences in crystal packing between the two polytypes.« less

Observation of a re-entrant phase transition in the molecular complex tris(μ 2-3,5-diisopropyl-1,2,4-triazolato-κ 2 N 1: N 2)trigold(I) under high pressure

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

Woodall, Christopher H.; Christensen, Jeppe; Skelton, Jonathan M.

We report a molecular crystal that exhibits four successive phase transitions under hydro­static pressure, driven by aurophilic interactions, with the ground-state structure re-emerging at high pressure. The effect of pressure on two polytypes of tris(μ 2-3,5-diiso­propyl-1,2,4-triazolato-κ 2 N 1: N 2)trigold(I) (denoted Form-I and Form-II) has been analysed using luminescence spectroscopy, single-crystal X-ray diffraction and first-principles computation. A unique phase behaviour was observed in Form-I, with a complex sequence of phase transitions between 1 and 3.5 GPa. The ambient C2/c mother cell transforms to a P2 1/n phase above 1 GPa, followed by a P2 1/a phase above 2 GPamore » and a large-volume C2/c supercell at 2.70 GPa, with the previously observed P2 1/n phase then reappearing at higher pressure. The observation of crystallographically identical low- and high-pressure P2 1/n phases makes this a rare example of a re-entrant phase transformation. The phase behaviour has been characterized using detailed crystallographic theory and modelling, and rationalized in terms of molecular structural distortions. The dramatic changes in conformation are correlated with shifts of the luminescence maxima, from a band maximum at 14040 cm –1 at 2.40 GPa, decreasing steeply to 13550 cm –1 at 3 GPa. A similar study of Form-II displays more conventional crystallographic behaviour, indicating that the complex behaviour observed in Form-I is likely to be a direct consequence of the differences in crystal packing between the two polytypes.« less

Insight into the Near-Conduction Band States at the Crystallized Interface between GaN and SiN x Grown by Low-Pressure Chemical Vapor Deposition.

PubMed

Liu, Xinyu; Wang, Xinhua; Zhang, Yange; Wei, Ke; Zheng, Yingkui; Kang, Xuanwu; Jiang, Haojie; Li, Junfeng; Wang, Wenwu; Wu, Xuebang; Wang, Xianping; Huang, Sen

2018-06-12

Constant-capacitance deep-level transient Fourier spectroscopy is utilized to characterize the interface between a GaN epitaxial layer and a SiN x passivation layer grown by low-pressure chemical vapor deposition (LPCVD). A near-conduction band (NCB) state E LP ( E C - E T = 60 meV) featuring a very small capture cross section of 1.5 × 10 -20 cm -2 was detected at 70 K at the LPCVD-SiN x /GaN interface. A partially crystallized Si 2 N 2 O thin layer was detected at the interface by high-resolution transmission electron microscopy. Based on first-principles calculations of crystallized Si 2 N 2 O/GaN slabs, it was confirmed that the NCB state E LP mainly originates from the strong interactions between the dangling bonds of gallium and its vicinal atoms near the interface. The partially crystallized Si 2 N 2 O interfacial layer might also give rise to the very small capture cross section of the E LP owing to the smaller lattice mismatch between the Si 2 N 2 O and GaN epitaxial layer and a larger mean free path of the electron in the crystallized portion compared with an amorphous interfacial layer.

[Generation of Superoxide Radicals by Complex III in Heart Mitochondria and Antioxidant Effect of Dinitrosyl Iron Complexes at Different Partial Pressure of Oxygen].

PubMed

Dudylina, A L; Ivanova, M V; Shumaev, K B; Ruuge, E K

2016-01-01

The EPR spin-trapping technique and EPR-oximetry were used to study generation of superoxide radicals in heart mitochondria isolated from Wistar rats under conditions of variable oxygen concentration. Lithium phthalocyanine and TEMPONE-15N-D16 were chosen to determine oxygen content in a gas-permeable capillary tube containing mitochondria. TIRON was used as a spin trap. We investigated the influence of different oxygen concentrations in incubation mixture and demonstrated that heart mitochondria can generate superoxide in complex III at different partial pressure of oxygen as well as under the conditions of deep hypoxia (< 5% O2). Dinitrosyl iron complexes with glutathione (the pharmaceutical drug "Oxacom") exerted an antioxidant effect, regardless of the value of the partial pressure of oxygen, but the magnitude and kinetic characteristics of the effect depended on the concentration of the drug.

Single photon ionization of van der Waals clusters with a soft x-ray laser: (CO2)n and (CO2)n(H2O)m.

PubMed

Heinbuch, S; Dong, F; Rocca, J J; Bernstein, E R

2006-10-21

Pure neutral (CO2)n clusters and mixed (CO2)n(H2O)m clusters are investigated employing time of flight mass spectroscopy and single photon ionization at 26.5 eV. The distribution of pure (CO2)n clusters decreases roughly exponentially with increasing cluster size. During the ionization process, neutral clusters suffer little fragmentation because almost all excess cluster energy above the vertical ionization energy is taken away by the photoelectron and only a small part of the photon energy is deposited into the (CO2)n cluster. Metastable dissociation rate constants of (CO2)n+ are measured in the range of (0.2-1.5) x 10(4) s(-1) for cluster sizes of 5< or =n< or =16. Mixed CO2-H2O clusters are studied under different generation conditions (5% and 20% CO2 partial pressures and high and low expansion pressures). At high CO2 concentration, predominant signals in the mass spectrum are the (CO2)n+ cluster ions. The unprotonated cluster ion series (CO2)nH2O+ and (CO2)n(H2O)2+ are also observed under these conditions. At low CO2 concentration, protonated cluster ions (H2O)nH+ are the dominant signals, and the protonated CO2(H2O)nH+ and unprotonated (H2O)n+ and (CO2)(H2O)n+ cluster ion series are also observed. The mechanisms and dynamics of the formation of these neutral and ionic clusters are discussed.

New structural phase obtained by exerting high pressure on (Br2)n@AFI composite material

NASA Astrophysics Data System (ADS)

Yao, Zhen; Lv, Jia-Yin; Liu, Bo; Liu, Bing-Bing; Yang, Bai

2018-06-01

In this paper, we present a theoretical study on the high-pressure behaviors of a (Br2)n@AlPO4-5 (AFI) peapod structure. The influence of the encapsulated Br2 molecule on the structural deformation of AFI crystal is analyzed using the volume-pressure function. The bonding process of the linearly arrayed Br2 molecule transferring to the bromine atomic chain is analyzed by the electron density distribution. A new high-pressure phase with P2 point group symmetry is obtained as the pressure increases to 34 GPa. In addition, electron density difference calculations are used to study the systematic charge transformation. Further analysis indicates that the encapsulated Br2 molecules can significantly modify the electronic structure of the AFI crystal. The band gap of the (Br2)n@AFI decreases with pressure and closes at 9 GPa. Moreover, the calculated bulk modulus and electronic properties indicate that the new structural phase is metallic with a high hardness, providing a new strategy for exploring novel nanomaterials.

Electron attachment to toluene in n-hexane and 2,2-dimethylbutane at high pressure

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

Itoh, Kengo; Nishikawa, Masaru; Holroyd, R.

The effect of dilute concentration of toluene on the electron mobility in two isometric hexanes was studied as a function of pressure from 1 bar to 3 kbar and at selected temperatures between 9 and 60[degrees]C. The effect of toluene on the mobility is small at 1 bar but quite large at the higher pressures. The results are interpreted in terms of reversible electron attachment to a toluene species which is the monomer in n-hexane. For this reaction [triangle]H[sub r] is - 12.0 kcal /mol in n-hexane at 2.5 kbar. In 2,2-dimethylbutane attachment to a dimeric species is indicated. Themore » volume changes for these attachment reactions are large, between [minus]80 and [minus]100 cm[sup 3]/mol. In hexane the volume changes are attributed in part to the electrostriction of the solvent by the toluene anion and in part to a positive molar volume of the electron. 19 refs., 8 figs., 3 tabs.« less

Surface reconstruction of GaAs(001) nitrided under the controlled As partial pressure [rapid communication

NASA Astrophysics Data System (ADS)

Imayoshi, Takahiro; Oigawa, Haruhiro; Shigekawa, Hidemi; Tokumoto, Hiroshi

2003-08-01

Under the controlled As partial pressure, the nitridation process of GaAs(0 0 1)-(2 × 4) surface was studied using a scanning tunneling microscope (STM) combined with an electron cyclotron resonance plasma-assisted molecular beam epitaxy system. With either prolonging the nitridation time or decreasing the As partial pressure, the previously reported (3 × 3) structure with two dimers per surface cell ((3 × 3)-2D) was found to progressively convert into a new (3 × 3) structure characterized by one dimer per surface cell ((3 × 3)-1D). Reversely the exposure to arsenic transformed the structure from (3 × 3)-1D to (3 × 3)-2D, suggesting that the topmost layer is composed of As 2-dimers. Based on these STM images together with the X-ray photoelectron spectroscopy data, we propose the new As 2-dimer coverage models to explain both (3 × 3)-1D and -2D structures involving the exchange reaction of arsenic with nitrogen in the subsurface region of GaAs.

Correlations of π N partial waves for multireaction analyses

DOE PAGES

Doring, M.; Revier, J.; Ronchen, D.; ...

2016-06-15

In the search for missing baryonic resonances, many analyses include data from a variety of pion- and photon-induced reactions. For elastic πN scattering, however, usually the partial waves of the SAID (Scattering Analysis Interactive Database) or other groups are fitted, instead of data. We provide the partial-wave covariance matrices needed to perform correlated χ 2 fits, in which the obtained χ 2 equals the actual χ 2 up to nonlinear and normalization corrections. For any analysis relying on partial waves extracted from elastic pion scattering, this is a prerequisite to assess the significance of resonance signals and to assign anymore » uncertainty on results. Lastly, the influence of systematic errors is also considered.« less

Effects of various oxygen partial pressures on Ti-doped ZnO thin film transistors fabricated on flexible plastic substrate

NASA Astrophysics Data System (ADS)

Cui, Guodong; Han, Dedong; Yu, Wen; Shi, Pan; Zhang, Yi; Huang, Lingling; Cong, Yingying; Zhou, Xiaoliang; Zhang, Xiaomi; Zhang, Shengdong; Zhang, Xing; Wang, Yi

2016-04-01

By applying a novel active layer of titanium zinc oxide (TiZO), we have successfully fabricated fully transparent thin-film transistors (TFTs) with a bottom gate structure fabricated on a flexible plastic substrate at low temperatures. The effects of various oxygen partial pressures during channel deposition were studied to improve the device performance. We found that the oxygen partial pressure during channel deposition has a significant impact on the performance of TiZO TFTs, and that the TFT developed under 10% oxygen partial pressure exhibits superior performance with a low threshold voltage (V th) of 2.37 V, a high saturation mobility (μsat) of 125.4 cm2 V-1 s-1, a steep subthreshold swing (SS) of 195 mV/decade and a high I on/I off ratio of 3.05 × 108. These results suggest that TiZO thin films are promising for high-performance fully transparent flexible TFTs and displays.

Optimizing the physical ergonomics indices for the use of partial pressure suits.

PubMed

Ding, Li; Li, Xianxue; Hedge, Alan; Hu, Huimin; Feathers, David; Qin, Zhifeng; Xiao, Huajun; Xue, Lihao; Zhou, Qianxiang

2015-03-01

This study developed an ergonomic evaluation system for the design of high-altitude partial pressure suits (PPSs). A total of twenty-one Chinese males participated in the experiment which tested three types of ergonomics indices (manipulative mission, operational reach and operational strength) were studied using a three-dimensional video-based motion capture system, a target-pointing board, a hand dynamometer, and a step-tread apparatus. In total, 36 ergonomics indices were evaluated and optimized using regression and fitting analysis. Some indices that were found to be linearly related and redundant were removed from the study. An optimal ergonomics index system was established that can be used to conveniently and quickly evaluate the performance of different pressurized/non-pressurized suit designs. The resulting ergonomics index system will provide a theoretical basis and practical guidance for mission planners, suit designers and engineers to design equipment for human use, and to aid in assessing partial pressure suits. Copyright © 2014 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Temperature dependence of partial conductivities of the BaZr0.7Ce0.2Y0.1O3-δ proton conductor

NASA Astrophysics Data System (ADS)

Heras-Juaristi, Gemma; Pérez-Coll, Domingo; Mather, Glenn C.

2017-10-01

Partial conductivities are presented for BaZr0.7Ce0.2Y0.1O3-δ, an important proton conductor for protonic-ceramic fuel cells and membrane reactors. Atmospheric dependencies of impedance performed in humidified and dry O2, air, N2 and H2(10%)/N2(90%) in the temperature range 300-900 °C, supported by the modified emf method, confirm significant electron-hole and protonic contributions to transport. For very reducing and wet atmospheres, the conductivity is predominantly ionic, with a higher participation of protons with decreasing temperature and increasing water-vapour partial pressure (pH2O). From moderately reducing conditions of wet N2 to wet O2, however, the conductivity is considerably influenced by electron holes as revealed by a significant dependence of total conductivity on oxygen partial pressure (pO2). With higher pH2O, proton transport increases, with a concomitant decrease of holes and oxygen vacancies. However, the effect of pH2O is also influenced by temperature, with a greater protonic contribution at both lower temperature and pO2. Values of proton transport number tH ≈ 0.63 and electronic transport number th ≈ 0.37 are obtained at 600 °C for pH2O = 0.022 atm and pO2 = 0.2 atm, whereas tH ≈ 0.95 and th ≈ 0.05 for pO2 = 10-5 atm. A hydration enthalpy of -109 kJ mol-1 is obtained in the range 600-900 °C.

Effect of O2 partial pressure on post annealed Ba2YCu3O(7-delta) thin films

NASA Astrophysics Data System (ADS)

Phillps, J. M.; Siegal, M. P.; Hou, S. Y.; Tiefel, T. H.; Marshall, J. H.

1992-04-01

Epitaxial films of Ba2YCu3O(7-delta) (BYCO) as thin as 250 A and with J(sub c)'s approaching those of the best in situ grown films can be formed by co-evaporating BaF2, Y, and Cu followed by a two-stage anneal. High quality films of these thicknesses become possible if low oxygen partial pressure (p(O2) = 4.3 Torr) is used during the high temperature portion of the anneal (T(sub a)). The BYCO melt line is the upper limit for T(sub a). The use of low p(O2) shifts the window for stable BYCO film growth to lower temperature, which allows the formation of smooth films with greater microstructural disorder than is found in films grown in p(O2) = 740 Torr at higher T(sub a). The best films annealed in p(O2) = 4.3 Torr have J(sub c) values a factor of four higher than do comparable films annealed in p(O2) = 740 Torr. The relationship between the T(sub a) required to grow films with the strongest pinning force and p(O2) is log (p(O2)) proportional to T(sub a) exp(1 exp a) independent of growth method (in situ or ex situ) over a range of five orders of magnitude of p(O2).

Negative pressure wound therapy for partial-thickness burns.

PubMed

Dumville, Jo C; Munson, Christopher

2012-12-12

A burn wound is a complex and evolving injury, with both local and systemic consequences. Burn treatments include a variety of dressings, as well as newer strategies, such as negative pressure wound therapy (NPWT), which, by means of a suction force that drains excess fluids from the burn, tries to promote the wound healing process and minimise progression of the burn wound. To assess the effectiveness of NPWT for people with partial-thickness burns. For this third update we searched the Cochrane Wounds Group Specialised Register (searched 18 May 2012); The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 5); Ovid MEDLINE (2010 to May Week 2 2012); Ovid MEDLINE (In-Process & Other Non-Indexed Citations 17 May 2012); Ovid EMBASE (2010 to 2012 Week 19); and EBSCO CINAHL (2010 to 16 May 2012). All randomised controlled trials (RCTs) and controlled clinical trials (CCTs) that evaluated the safety and effectiveness of NPWT for partial-thickness burns. Two review authors used standardised forms, and extracted the data independently. We assessed each trial for risk of bias, and resolved differences by discussion. One RCT, that was an interim report, satisfied the inclusion criteria. We undertook a narrative synthesis of results, as the absence of data and poor reporting precluded us from carrying out any formal statistical analysis. The trial was at high risk of bias. There was not enough evidence available to permit any conclusions to be drawn regarding the use of NPWT for treatment of partial-thickness burn wounds.

Critical hematocrit and oxygen partial pressure in the beating heart of pigs.

PubMed

Hiebl, B; Mrowietz, C; Ploetze, K; Matschke, K; Jung, F

2010-12-01

In cardiac surgery the substitution of lost blood volume by plasma substitutes is a common therapeutical approach. None of the currently available blood substitutes has a sufficient oxygen transport capacity. This can limit the functional integrity of the myocardium known as highly oxygen consumptive. The study was aimed to get information about the minimal hematocrit, also known as critical hematocrit (cHct), which guarantees a stable and adequate oxygen partial pressure in the myocardium (pO2). In adult female pigs (n=7) the hematocrit was reduced by isovolemic blood dilution with an intravenous infusion of isotonic 4% gelatine polysuccinate solution, The substituted blood volume ranged between 3000ml and 7780ml (mean: 5254±1672ml). In all animals the pO2 of the myocardium of the beating heart and of the resting skeletal muscle increased until blood dilution resulted in a Hct decrease down to 15%. Further blood dilution resulted in a decrease of the pO2. Only after the Hct was <10% the pO2 was lower than before blood dilution and accompanied by a lethal ischemia of the myocardium. These data indicate a cHct of about 10% in the pig animal model. Copyright © 2010 Elsevier Inc. All rights reserved.

High-Pressure Synchrotron Infrared Absorption and Raman Spectroscopy of ζ-N_2

NASA Astrophysics Data System (ADS)

Gregoryanz, E.; Goncharov, A. F.; Mao, H. K.; Hemley, R. J.

2000-03-01

Infrared mid-IR and Raman spectra of high-pressure, low-temperature phases of solid nitrogen have been measured to above 40 GPa. The transition to the lower-symmetry ordered phase ζ at 21 GPa, reported by Schiferl et al. [1]. has been confirmed. We observe three Raman-active and two IR components of the nu2 stretching mode (disk-like molecules) and only one Raman-active component of the nu1 mode (sphere-like molecules). All the vibron modes increase frequency with pressure. The structure of ζ-N2 phase is discussed. [1] Schiferl et al., J. Phys. Chem., 89, 2324 (1985).

Oxidation of C/SiC Composites at Reduced Oxygen Partial Pressures

NASA Technical Reports Server (NTRS)

Opila, Elizabeth J.; Serra, Jessica

2009-01-01

Carbon-fiber reinforced SiC (C/SiC) composites are proposed for leading edge applications of hypersonic vehicles due to the superior strength of carbon fibers at high temperatures (greater than 1500 C). However, the vulnerability of the carbon fibers in C/SiC to oxidation over a wide range of temperatures remains a problem. Previous oxidation studies of C/SiC have mainly been conducted in air or oxygen, so that the oxidation behavior of C/SiC at reduced oxygen partial pressures of the hypersonic flight regime are less well understood. In this study, both carbon fibers and C/SiC composites were oxidized over a wide range of temperatures and oxygen partial pressures to facilitate the understanding and modeling of C/SiC oxidation kinetics for hypersonic flight conditions.

Comparative study of (0001) and (11\\bar{2}2) InGaN based light emitting diodes

NASA Astrophysics Data System (ADS)

Pristovsek, Markus; Humphreys, Colin J.; Bauer, Sebastian; Knab, Manuel; Thonke, Klaus; Kozlowski, Grzegorz; O'Mahony, Donagh; Maaskant, Pleun; Corbett, Brian

2016-05-01

We have systematically investigated the doping of (11\\bar{2}2) with Si and Mg by metal-organic vapour phase epitaxy for light emitting diodes (LEDs). By Si doping of GaN we reached electron concentrations close to 1020 cm-3, but the topography degrades above mid 1019 cm-3. By Mg doping we reached hole concentrations close to 5 × 1017 cm-3, using Mg partial pressures about 3× higher than those for (0001). Exceeding the maximum Mg partial pressure led to a quick degradation of the sample. Low resistivities as well as high hole concentrations required a growth temperature of 900 °C or higher. At optimised conditions the electrical properties as well as the photoluminescence of (11\\bar{2}2) p-GaN were similar to (0001) p-GaN. The best ohmic p-contacts were achieved by NiAg metallisation. A single quantum well LED emitting at 465 nm was realised on (0001) and (11\\bar{2}2). Droop (sub-linear increase of the light output power) occurred at much higher current densities on (11\\bar{2}2). However, the light output of the (0001) LED was higher than that of (11\\bar{2}2) until deep in the droop regime. Our LEDs as well as those in the literature indicate a reduction in efficiency from (0001) over semi-polar to non-polar orientations. We propose that reduced fields open a loss channel for carriers.

Changes in Cerebral Partial Oxygen Pressure and Cerebrovascular Reactivity During Intracranial Pressure Plateau Waves.

PubMed

Lang, Erhard W; Kasprowicz, Magdalena; Smielewski, Peter; Pickard, John; Czosnyka, Marek

2015-08-01

Plateau waves in intracranial pressure (ICP) are frequently recorded in neuro intensive care and are not yet fully understood. To further investigate this phenomenon, we analyzed partial pressure of cerebral oxygen (pbtO2) and a moving correlation coefficient between ICP and mean arterial blood pressure (ABP), called PRx, along with the cerebral oxygen reactivity index (ORx), which is a moving correlation coefficient between cerebral perfusion pressure (CPP) and pbtO2 in an observational study. We analyzed 55 plateau waves in 20 patients after severe traumatic brain injury. We calculated ABP, ABP pulse amplitude (ampABP), ICP, CPP, pbtO2, heart rate (HR), ICP pulse amplitude (ampICP), PRx, and ORx, before, during, and after each plateau wave. The analysis of variance with Bonferroni post hoc test was used to compare the differences in the variables before, during, and after the plateau wave. We considered all plateau waves, even in the same patient, independent because they are separated by long intervals. We found increases for ICP and ampICP according to our operational definitions for plateau waves. PRx increased significantly (p = 0.00026), CPP (p < 0.00001) and pbtO2 (p = 0.00007) decreased significantly during the plateau waves. ABP, ampABP, and HR remained unchanged. PRx during the plateau was higher than before the onset of wave in 40 cases (73 %) with no differences in baseline parameters for those with negative and positive ΔPRx (difference during and after). ORx showed an increase during and a decrease after the plateau waves, however, not statistically significant. PbtO2 overshoot after the wave occurred in 35 times (64 %), the mean difference was 4.9 ± 4.6 Hg (mean ± SD), and we found no difference in baseline parameters between those who overshoot and those who did not overshoot. Arterial blood pressure remains stable in ICP plateau waves, while cerebral autoregulatory indices show distinct changes, which indicate cerebrovascular

Compositional dependent partial molar volume and compressibility of CO2 in rhyolite, phonolite and basalt glasses

NASA Astrophysics Data System (ADS)

Lerch, P.; Seifert, R.; Malfait, W. J.; Sanchez-Valle, C.

2012-12-01

Carbon dioxide is the second most abundant volatile in magmatic systems and plays an important role in many magmatic processes, e.g. partial melting, volatile saturation, outgassing. Despite this relevance, the volumetric properties of carbon-bearing silicates at relevant pressure and temperature conditions remain largely unknown because of considerable experimental difficulties associated with in situ measurements. Density and elasticity measurements on quenched glasses can provide an alternative source of information. For dissolved water, such measurements indicate that the partial molar volume is independent of compositions at ambient pressure [1], but the partial molar compressibility is not [2, 3]. Thus the partial molar volume of water may depend on melt composition at elevated pressure. For dissolved CO2, no such data is available. In order to constrain the effect of magma composition on the partial molar volume and compressibility of dissolved carbon, we determined the density and elasticity for three series of carbon-bearing basalt, phonolite and rhyolite glasses, quenched from 3.5 GPa and relaxed at ambient pressure. The CO2 content varies between 0 to 3.90 wt% depending on the glass composition. Glass densities were determined using the sink/float method in a diiodomethane (CH2I2) - acetone mixture. Brillouin measurements were conducted on relaxed and unrelaxed silicate glasses in platelet geometry to determine the compressional (VP) and shear (VS) wave velocities and elastic moduli. The partial molar volume of CO2 in rhyolite, phonolite and basalt glasses is 25.4 ± 0.9, 22.1 ± 0.6 and 26.6 ±1.8 cm3/mol, respectively. Thus, unlike for dissolved water, the partial molar volume of CO2 displays a resolvable compositional effect. Although the composition and CO2/carbonate speciation of the phonolite glasses is intermediate between that of the rhyolite and basalt glasses, the molar volume is not. Similar to dissolved water, the partial molar bulk modulus

High pressure synthesis and magnetic studies of quasi one dimensional systems Sr{sub n-1} Cu{sub n+1} O{sub 2n} (n=3,5)

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

Azuma, M.; Hiroi, Z.; Takano, M.

1994-12-31

SrCu{sub 2}O{sub 3} and Sr{sub 2}Cu{sub 3}O{sub 5} containing two-leg and three-leg S=1/2 ladders made of antiferromagnetic Cu-O-Cu linear bonds, respectively, were synthesized at high pressure, and their crystallographic and magnetic properties were investigated. Both susceptibility and T{sub 1} data of NMR revealed the existence of a large spin gap only for SrCu{sub 2}O{sub 3}. Superconductivity, which had been predicted theoretically for carrier-doped SrCu{sub 2}O{sub 3} could not be realized although partial substitution of La{sup 3+} for Sr{sup 2+} seemed to be carried out successfully. Electron carriers injected seems to remain localized.

Measurement of Local Partial Pressure of Oxygen in the Brain Tissue under Normoxia and Epilepsy with Phosphorescence Lifetime Microscopy

PubMed Central

Zhang, Cong; Bélanger, Samuel; Pouliot, Philippe; Lesage, Frédéric

2015-01-01

In this work a method for measuring brain oxygen partial pressure with confocal phosphorescence lifetime microscopy system is reported. When used in conjunction with a dendritic phosphorescent probe, Oxyphor G4, this system enabled minimally invasive measurements of oxygen partial pressure (pO2) in cerebral tissue with high spatial and temporal resolution during 4-AP induced epileptic seizures. Investigating epileptic events, we characterized the spatio-temporal distribution of the "initial dip" in pO2 near the probe injection site and along nearby arterioles. Our results reveal a correlation between the percent change in the pO2 signal during the "initial dip" and the duration of seizure-like activity, which can help localize the epileptic focus and predict the length of seizure. PMID:26305777

Measurement of Local Partial Pressure of Oxygen in the Brain Tissue under Normoxia and Epilepsy with Phosphorescence Lifetime Microscopy.

PubMed

Zhang, Cong; Bélanger, Samuel; Pouliot, Philippe; Lesage, Frédéric

2015-01-01

In this work a method for measuring brain oxygen partial pressure with confocal phosphorescence lifetime microscopy system is reported. When used in conjunction with a dendritic phosphorescent probe, Oxyphor G4, this system enabled minimally invasive measurements of oxygen partial pressure (pO2) in cerebral tissue with high spatial and temporal resolution during 4-AP induced epileptic seizures. Investigating epileptic events, we characterized the spatio-temporal distribution of the "initial dip" in pO2 near the probe injection site and along nearby arterioles. Our results reveal a correlation between the percent change in the pO2 signal during the "initial dip" and the duration of seizure-like activity, which can help localize the epileptic focus and predict the length of seizure.

Toxicity of elevated partial pressures of carbon dioxide to invasive New Zealand mudsnails

USGS Publications Warehouse

Nielson, R. Jordan; Moffitt, Christine M.; Watten, Barnaby J.

2012-01-01

The authors tested the efficacy of elevated partial pressures of CO2 to kill invasive New Zealand mudsnails. The New Zealand mudsnails were exposed to 100 kPa at three water temperatures, and the survival was modeled versus dose as cumulative °C-h. We estimated an LD50 of 59.4°C-h for adult and juvenile New Zealand mudsnails. The results suggest that CO2 may be an effective and inexpensive lethal tool to treat substrates, tanks, or materials infested with New Zealand mudsnails.

Classifying Acute Respiratory Distress Syndrome Severity: Correcting the Arterial Oxygen Partial Pressure to Fractional Inspired Oxygen at Altitude.

PubMed

Pérez-Padilla, Rogelio; Hernández-Cárdenas, Carmen Margarita; Lugo-Goytia, Gustavo

2016-01-01

In the well-known Berlin definition of acute respiratory distress syndrome (ARDS), there is a recommended adjustment for arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FIO2) at altitude, but without a reference as to how it was derived.

Negative pressure wound therapy for partial-thickness burns.

PubMed

Dumville, Jo C; Munson, Christopher; Christie, Janice

2014-12-15

A burn wound is a complex and evolving injury, with both local and systemic consequences. Burn treatments include a variety of dressings, as well as newer strategies, such as negative pressure wound therapy (NPWT), which, by means of a suction force that drains excess fluids from the burn, tries to promote the wound healing process and minimise progression of the burn wound. To assess the effectiveness of NPWT for people with partial-thickness burns. We searched the Cochrane Wounds Group Specialised Register (searched 04 September 2014); The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2014, Issue 8). All randomised controlled trials (RCTs) and controlled clinical trials (CCTs) that evaluated the safety and effectiveness of NPWT for partial-thickness burns. Two review authors used standardised forms, and extracted the data independently. We assessed each trial for risk of bias, and resolved differences by discussion. One RCT, that was an interim report, satisfied the inclusion criteria. We undertook a narrative synthesis of results, as the absence of data and poor reporting precluded us from carrying out any formal statistical analysis. The trial was at high risk of bias. There was not enough evidence available to permit any conclusions to be drawn regarding the use of NPWT for treatment of partial-thickness burn wounds.

Hybrid Global Model Simulations of He/N2 and He/H2O Atmospheric Pressure Capacitive Discharges

NASA Astrophysics Data System (ADS)

Lieberman, M. A.; Kawamura, E.; Ke, Ding; Lichtenberg, A. J.; Chabert, P.; Lazzaroni, C.

2014-10-01

We used 1D particle-in-cell (PIC) simulations of an atmospheric He/0.1%N2 discharge with simplified chemistry to guide the development of a hybrid analytical/numerical global model that includes electron multiplication and two classes of electrons: ``hot'' electrons associated with the sheaths, and ``warm'' electrons associated with the bulk. The model and PIC results show reasonable agreement and indicate a transition from a low power α-mode with a relatively high bulk electron temperature Te to a high power γ-mode with a low Te. The transition is accompanied by an increase in density and a decrease in sheath widths. Water is a trace gas of bio-medical interest since it may arise from contact with skin. We use the hybrid global model to simulate a chemically complex, bounded He/H2O atmospheric pressure discharge, including 148 volume reactions among 43 species, and including clusters up to H19O9+.For a planar discharge with a 1 cm electrode radius and a 0.5 mm gap driven at 13.56 MHz, we determine the depletion and diffusion effects and the α to γ transition for secondary emission γse = 0.25 over a range of rf currents and external H2O concentrations. Each simulation takes about 2 minutes on a moderate laptop. This work was partially supported by the Department of Energy Office of Fusion Energy Science Contract DE-SC000193 and by the Natural Science Foundation of China Contract 11375042.

Oxygen partial pressure modulates 67-kDa laminin receptor expression, leading to altered activity of the green tea polyphenol, EGCG.

PubMed

Tsukamoto, Shuntaro; Yamashita, Shuya; Kim, Yoon Hee; Kumazoe, Motofumi; Huang, Yuhui; Yamada, Koji; Tachibana, Hirofumi

2012-09-21

(-)-Epigallocatechin-3-O-gallate (EGCG) exhibits anti-tumor activity mediated via the 67-kDa laminin receptor (67LR). In this study, we found that 67LR protein levels are reduced by exposure to low O(2) levels (5%), without affecting the expression of HIF-1α. We also found that EGCG-induced anti-cancer activity is abrogated under low O(2) levels (5%) in various cancer cells. Notably, treatment with the proteasome inhibitor, prevented down-regulation of 67LR and restored sensitivity to EGCG under 5% O(2). In summary, 67LR expression is highly sensitive to O(2) partial pressure, and the activity of EGCG can be regulated in cancer cells by O(2) partial pressure. Copyright © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Pressure-Induced Polymerization of LiN(CN) 2

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

Keefer, Derek W.; Gou, Huiyang; Purdy, Andrew P.

The high-pressure behavior of lithium dicyanamide (LiN(CN) 2) was studied with in situ Raman and infrared (IR) spectroscopies, and synchrotron angle-dispersive powder X-ray diffraction (PXRD) in a diamond anvil cell (DAC) to 22 GPa. The fundamental vibrational modes associated with molecular units were assigned using a combination of experimental data and density functional perturbation theory. Some low-frequency modes were observed for the first time. On the basis of spectroscopic and diffraction data, we suggest a polymorphic phase transformation at ~8 GPa, wherein dicyanamide ions remain as discrete molecular species. Above ca. 18 GPa, dicyanamide units polymerize, forming a largely disorderedmore » network, and the extent of polymerization may be increased by annealing at elevated temperature. The polymerized product consists of tricyanomelaminate-like groups containing sp 2-hybidized carbon–nitrogen bonds and exhibits a visible absorption edge near 540 nm. The product is recoverable to ambient conditions but is not stable in air/moisture.« less

Reproducing early Martian atmospheric carbon dioxide partial pressure by modeling the formation of Mg-Fe-Ca carbonate identified in the Comanche rock outcrops on Mars

NASA Astrophysics Data System (ADS)

Berk, Wolfgang; Fu, Yunjiao; Ilger, Jan-Michael

2012-10-01

The well defined composition of the Comanche rock's carbonate (Magnesite0.62Siderite0.25Calcite0.11Rhodochrosite0.02) and its host rock's composition, dominated by Mg-rich olivine, enable us to reproduce the atmospheric CO2partial pressure that may have triggered the formation of these carbonates. Hydrogeochemical one-dimensional transport modeling reveals that similar aqueous rock alteration conditions (including CO2partial pressure) may have led to the formation of Mg-Fe-Ca carbonate identified in the Comanche rock outcrops (Gusev Crater) and also in the ultramafic rocks exposed in the Nili Fossae region. Hydrogeochemical conditions enabling the formation of Mg-rich solid solution carbonate result from equilibrium species distributions involving (1) ultramafic rocks (ca. 32 wt% olivine; Fo0.72Fa0.28), (2) pure water, and (3) CO2partial pressures of ca. 0.5 to 2.0 bar at water-to-rock ratios of ca. 500 molH2O mol-1rock and ca. 5°C (278 K). Our modeled carbonate composition (Magnesite0.64Siderite0.28Calcite0.08) matches the measured composition of carbonates preserved in the Comanche rocks. Considerably different carbonate compositions are achieved at (1) higher temperature (85°C), (2) water-to-rock ratios considerably higher and lower than 500 mol mol-1 and (3) CO2partial pressures differing from 1.0 bar in the model set up. The Comanche rocks, hosting the carbonate, may have been subjected to long-lasting (>104 to 105 years) aqueous alteration processes triggered by atmospheric CO2partial pressures of ca. 1.0 bar at low temperature. Their outcrop may represent a fragment of the upper layers of an altered olivine-rich rock column, which is characterized by newly formed Mg-Fe-Ca solid solution carbonate, and phyllosilicate-rich alteration assemblages within deeper (unexposed) units.

Flow-independent dynamics in aneurysm (FIDA): pressure measurements following partial and complete flow impairment in experimental aneurysm model

PubMed Central

Watanabe, Masaki; Chaudhry, Saqib A; Qureshi, Adnan I

2014-01-01

Background: There have been growing concerns regarding delayed aneurysm rupture subsequent to the flow-diverting stent deployment. Therefore, more investigations are needed regarding hemodynamic changes secondary to flow-diverting stent deployment. Objective: To study intra-aneurysmal and perianeurysmal pressures after partial and complete flow impairment into the aneurysm. Methods A silicone model of an 8-mm-sized aneurysm (neck diameter: 5 mm, vessel size: 4 mm) was used. The aneurysm wall was encapsulated and sealed within a 5 ml syringe filled with saline and a pressure sensor guide wire (ComboWire, Volcano Corp.) to detect pressure changes in the perivascular compartment (outer aneurysm wall). A second pressure sensor guide wire was advanced inside the aneurysm sac. Both pressure sensors were continuously measuring pressure inside and outside the aneurysm under pulsatile flow under the following conditions: 1) baseline (reference); 2) a 16 mm by 3.75 mm flow-diverting stent (ev3/Covidien Vascular, Mansfield, MA) deployed in front of the aneurysm; 3) two flow-diverting stents (16 mm by 3.5 mm) were deployed; and 4) a covered stent (4 mm by 16 mm VeriFlex coronary artery stent covered with rubber sheet) was deployed. Results: Mean (±SD) baseline pressures inside and outside the aneurysm were 53.9 (±2.4) mmHg (range 120–40 mmHg) and 15.4 (±0.7) mmHg (range 40–8mmHg), respectively. There was no change in pressure inside and outside the aneurysm after deploying the first and second flow-diverting stents (partial flow impairment) and it remained at 53.9 (±2.7) mmHg and 14.9 (±1) mmHg for the pressure inside and outside the aneurysm, respectively. The pressure recording from outside the aneurysm dropped from 15.4 (±0.7) mmHg to 0.3 (±0.7) mmHg after deploying the covered stent (complete flow impairment). There was no change in pressure inside the aneurysm after deploying the covered stent. Mean (±SD) pressure within the aneurysm was 55.1 (±1.7) mmHg and

Relating oxygen partial pressure, saturation and content: the haemoglobin-oxygen dissociation curve.

PubMed

Collins, Julie-Ann; Rudenski, Aram; Gibson, John; Howard, Luke; O'Driscoll, Ronan

2015-09-01

The delivery of oxygen by arterial blood to the tissues of the body has a number of critical determinants including blood oxygen concentration (content), saturation (S O2 ) and partial pressure, haemoglobin concentration and cardiac output, including its distribution. The haemoglobin-oxygen dissociation curve, a graphical representation of the relationship between oxygen satur-ation and oxygen partial pressure helps us to understand some of the principles underpinning this process. Historically this curve was derived from very limited data based on blood samples from small numbers of healthy subjects which were manipulated in vitro and ultimately determined by equations such as those described by Severinghaus in 1979. In a study of 3524 clinical specimens, we found that this equation estimated the S O2 in blood from patients with normal pH and S O2 >70% with remarkable accuracy and, to our knowledge, this is the first large-scale validation of this equation using clinical samples. Oxygen saturation by pulse oximetry (S pO2 ) is nowadays the standard clinical method for assessing arterial oxygen saturation, providing a convenient, pain-free means of continuously assessing oxygenation, provided the interpreting clinician is aware of important limitations. The use of pulse oximetry reduces the need for arterial blood gas analysis (S aO2 ) as many patients who are not at risk of hypercapnic respiratory failure or metabolic acidosis and have acceptable S pO2 do not necessarily require blood gas analysis. While arterial sampling remains the gold-standard method of assessing ventilation and oxygenation, in those patients in whom blood gas analysis is indicated, arterialised capillary samples also have a valuable role in patient care. The clinical role of venous blood gases however remains less well defined.

Superconducting Bi 2Te: Pressure-induced universality in the (Bi 2) m(Bi 2Te 3) n series

DOE PAGES

Stillwell, Ryan L.; Jeffries, Jason R.; Jenei, Zsolt; ...

2016-03-09

Using high-pressure magnetotransport techniques we have discovered superconductivity in Bi 2Te, a member of the infinitely adaptive (Bi 2)m(Bi 2Te 3)n series, whose end members, Bi and Bi 2Te 3, can be tuned to display topological surface states or superconductivity. Bi 2Te has a maximum T c = 8.6 K at P = 14.5 GPa and goes through multiple high pressure phase transitions, ultimately collapsing into a bcc structure that suggests a universal behavior across the series. High-pressure magnetoresistance and Hall measurements suggest a semi-metal to metal transition near 5.4 GPa, which accompanies the hexagonal to intermediate phase transition seenmore » via x-ray diffraction measurements. In addition, the linearity of H c2 (T) exceeds the Werthamer-Helfand-Hohenberg limit, even in the extreme spin-orbit scattering limit, yet is consistent with other strong spin-orbit materials. Furthermore, considering these results in combination with similar reports on strong spin-orbit scattering materials seen in the literature, we suggest the need for a new theory that can address the unconventional nature of their superconducting states.« less

Chemical looping of metal nitride catalysts: low-pressure ammonia synthesis for energy storage† †Electronic supplementary information (ESI) available: Experimental and computational details, free energy plots for the NH3 evolution and N2 reduction with Co3N/Co, Fe4N/Fe, Mn5N2/Mn4N, Mo2N/Mo, CrN/Cr2N, TaN/Ta2N, NbN/Nb2N, Li3N/LiH, Ba3N2/BaH2, Sr3N2/SrH2, and Ca3N2/CaH2, surface oxidation energetics, ΔGvac[NH*x, yH*] based on gas phase H2 as hydrogen source, NH3 evolution with Fe-doped Mn4N, NH3 evolution with Mn6N2.58, Ca3N2 and Sr2N after correcting for partial nitride hydrolysis, NH3 yield from Ca3N2vs. time and H2 gas flow rate. See DOI: 10.1039/c5sc00789e

PubMed Central

Avram, A. M.; Peterson, B. A.; Pfromm, P. H.; Peterson, A. A.

2015-01-01

The activity of many heterogeneous catalysts is limited by strong correlations between activation energies and adsorption energies of reaction intermediates. Although the reaction is thermodynamically favourable at ambient temperature and pressure, the catalytic synthesis of ammonia (NH3), a fertilizer and chemical fuel, from N2 and H2 requires some of the most extreme conditions of the chemical industry. We demonstrate how ammonia can be produced at ambient pressure from air, water, and concentrated sunlight as renewable source of process heat via nitrogen reduction with a looped metal nitride, followed by separate hydrogenation of the lattice nitrogen into ammonia. Separating ammonia synthesis into two reaction steps introduces an additional degree of freedom when designing catalysts with desirable activation and adsorption energies. We discuss the hydrogenation of alkali and alkaline earth metal nitrides and the reduction of transition metal nitrides to outline a promoting role of lattice hydrogen in ammonia evolution. This is rationalized via electronic structure calculations with the activity of nitrogen vacancies controlling the redox-intercalation of hydrogen and the formation and hydrogenation of adsorbed nitrogen species. The predicted trends are confirmed experimentally with evolution of 56.3, 80.7, and 128 μmol NH3 per mol metal per min at 1 bar and above 550 °C via reduction of Mn6N2.58 to Mn4N and hydrogenation of Ca3N2 and Sr2N to Ca2NH and SrH2, respectively. PMID:29218166

29Si nuclear magnetic resonance study of URu 2Si 2 under pressure

DOE PAGES

Shirer, K. R.; Dioguardi, A. P.; Bush, B. T.; ...

2015-12-01

Here, we report 29Si nuclear magnetic resonance measurements of single crystals and aligned powders of URu 2Si 2 under pressure in the hidden order and paramagnetic phases. We find evidence for a reduction of the Knight shift with applied pressure, consistent with previous measurements of the static magnetic susceptibility. Previous measurements of the spin lattice relaxation time revealed a partial suppression of the density of states below 30 K. Here, we find that the temperature at which this suppression occurs is enhanced with applied pressure.

The Effect of Oxygen Partial Pressure on Microstructure and Properties of Fe40Al Alloy Sintered under Vacuum

PubMed Central

Siemiaszko, Dariusz; Kowalska, Beata; Jóźwik, Paweł; Kwiatkowska, Monika

2015-01-01

This paper presents the results of studies on the influence of oxygen partial pressure (vacuum level in the chamber) on the properties of FeAl intermetallics. One of the problems in the application of classical methods of prepared Fe-Al intermetallic is the occurrence of oxides. Applying a vacuum during sintering should reduce this effect. In order to analyze the effect of oxygen partial pressure on sample properties, five samples were processed (by a pressure-assisted induction sintering—PAIS method) under the following pressures: 3, 8, 30, 80, and 300 mbar (corresponding to oxygen partial pressures of 0.63, 1.68, 6.3, 16.8, and 63 mbar, respectively). The chemical and phase composition, hardness, density, and microstructure observations indicate that applying a vacuum significantly impacts intermetallic samples. The compact sintered at pressure 3 mbar is characterized by the most homogeneous microstructure, the highest density, high hardness, and nearly homogeneous chemical composition. PMID:28788015

Effect of methane partial pressure on the performance of a membrane biofilm reactor coupling methane-dependent denitrification and anammox.

PubMed

Cai, Chen; Hu, Shihu; Chen, Xueming; Ni, Bing-Jie; Pu, Jiaoyang; Yuan, Zhiguo

2018-10-15

Complete nitrogen removal has recently been demonstrated by integrating anaerobic ammonium oxidation (anammox) and denitrifying anaerobic methane oxidation (DAMO) processes. In this work, the effect of methane partial pressure on the performance of a membrane biofilm reactor (MBfR) consisting of DAMO and anammox microorganisms was evaluated. The activities of DAMO archaea and DAMO bacteria in the biofilm increased significantly with increased methane partial pressure, from 367 ± 9 and 58 ± 22 mg-N L -1 d -1 to 580 ± 12 and 222 ± 22 mg-N L -1 d -1 , respectively, while the activity of anammox bacteria only increased slightly, when the methane partial pressure was elevated from 0.24 to 1.39 atm in the short-term batch tests. The results were supported by a long-term (seven weeks) continuous test, when the methane partial pressure was dropped from 1.39 to 0.78 atm. The methane utilization efficiency was always above 96% during both short-term and long-term tests. Taken together, nitrogen removal rate (especially the nitrate reduction rate by DAMO archaea) and methane utilization efficiency could be maintained at high levels in a broad range of methane partial pressure (0.24-1.39 atm in this study). In addition, a previously established DAMO/anammox biofilm model was used to analyze the experimental data. The observed impacts of methane partial pressure on biofilm activity were well explained by the modeling results. These results suggest that methane partial pressure can potentially be used as a manipulated variable to control reaction rates, ultimately to maintain high nitrogen removal efficiency, according to nitrogen loading rate. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis of Size-Tunable CO2-Philic Imprinted Polymeric Particles (MIPs) for Low-Pressure CO2 Capture Using Oil-in-Oil Suspension Polymerization.

PubMed

Nabavi, Seyed Ali; Vladisavljević, Goran T; Zhu, Yidi; Manović, Vasilije

2017-10-03

Highly selective molecularly imprinted poly[acrylamide-co-(ethylene glycol dimethacrylate)] polymer particles (MIPs) for CO 2 capture were synthesized by suspension polymerization via oil-in-oil emulsion. Creation of CO 2 -philic, amide-decorated cavities in the polymer matrix led to a high affinity to CO 2 . At 0.15 bar CO 2 partial pressure, the CO 2 /N 2 selectivity was 49 (corresponding to 91% purity of the gas stream after regeneration), and reached 97 at ultralow CO 2 partial pressures. The imprinted polymers showed considerably higher CO 2 uptakes compared to their nonimprinted counterparts, and the maximum equilibrium CO 2 capture capacity of 1.1 mmol g -1 was achieved at 273 K. The heat of adsorption was below 32 kJ mol -1 and the temperature of onset of intense thermal degradation was 351-376 °C. An increase in monomer-to-cross-linker molar ratio in the dispersed phase up to 1:2.5 led to a higher affinity toward CO 2 due to higher density of selective amide groups in the polymer network. MIPs are a promising option for industrial packed and fluidized bed CO 2 capture systems due to large particles with a diameter up to 1200 μm and irregular oblong shapes formed due to arrested coalescence during polymerization, occurring as a result of internal elasticity of the partially polymerized semisolid drops.

Introduction to total- and partial-pressure measurements in vacuum systems

NASA Technical Reports Server (NTRS)

Outlaw, R. A.; Kern, F. A.

1989-01-01

An introduction to the fundamentals of total and partial pressure measurement in the vacuum regime (760 x 10 to the -16th power Torr) is presented. The instrument most often used in scientific fields requiring vacuum measurement are discussed with special emphasis on ionization type gauges and quadrupole mass spectrometers. Some attention is also given to potential errors in measurement as well as calibration techniques.

Effect of Pressure on Absorption Spectra of Lycopene in n-Hexane and CS2 Solvents

NASA Astrophysics Data System (ADS)

Zhang, Wei; Liu, Wei-Long; Zheng, Zhi-Ren; Huo, Ming-Ming; Li, Ai-Hua; Yang, Bin

2010-01-01

The absorption spectra of lycopene in n-hexane and CS2 are measured under high pressure and the results are compared with β-carotene. In the lower pressure range, the deviation from the linear dependence on the Bayliss parameter (BP) for β-carotene is more visible than that for lycopene. With the further increase of the solvent BP, the 0-0 bands of lycopene and β-carotene red shift at almost the same rate in n-hexane; however, the 0-0 band of lycopene red shifts slower than that of β-carotene in CS2. The origins of these diversities are discussed taking into account the dispersion interactions and structures of solute and solvent molecules.

Effect of CH4 on the CO2 breakthrough pressure and permeability of partially saturated low-permeability sandstone in the Ordos Basin, China

NASA Astrophysics Data System (ADS)

Zhao, Yan; Yu, Qingchun

2018-01-01

The behavior of CO2 that coexists with CH4 and the effect of CH4 on the CO2 stream need to be deeply analyzed and studied, especially in the presence of water. Our previous studies investigated the breakthrough pressure and permeability of pure CO2 in five partially saturated low-permeability sandstone core samples from the Ordos Basin, and we concluded that rocks with a small pore size and low permeability show considerable sealing capacity even under unsaturated conditions. In this paper, we selected three of these samples for CO2-CH4 gas-mixture breakthrough experiments under various degrees of water saturation. The breakthrough experiments were performed by increasing the gas pressure step by step until breakthrough occurred. Then, the effluent gas mixture was collected for chromatographic partitioning analysis. The results indicate that CH4 significantly affects the breakthrough pressure and permeability of CO2. The presence of CH4 in the gas mixture increases the interfacial tension and, thus, the breakthrough pressure. Therefore, the injected gas mixture that contains the highest (lowest) mole fraction of CH4 results in the largest (smallest) breakthrough pressure. The permeability of the gas mixture is greater than that for pure CO2 because of CH4, and the effective permeability decreases with increased breakthrough pressure. Chromatographic partitioning of the effluent mixture gases indicates that CH4 breaks through ahead of CO2 as a result of its weaker solubility in water. Correlations are established between (1) the breakthrough pressure and water saturation, (2) the effective permeability and water saturation, (3) the breakthrough pressure and effective permeability, and (4) the mole fraction of CO2/CH4 in the effluent mixture gases and water saturation. These results deepen our understanding of the multi-phase flow behavior in the porous media under unsaturated conditions, which have implications for formulating emergency response plans for gas

Electronic and optical properties of Fe2SiO4 under pressure effect: ab initio study

NASA Astrophysics Data System (ADS)

Xiao, Lingping; Li, Xiaobin; Yang, Xue

2018-05-01

We report first-principles studies the structural, electronic, and optical properties of the Fe2SiO4 fayalite in orthorhombic structure, including pressure dependence of structural parameters, band structures, density of states, and optical constants up to 30 GPa. The calculated results indicate that the linear compressibility along b axis is significantly higher than a and c axes, which is in agreement with earlier work. Meanwhile, the pressure dependence of the electronic band structure, density of states and partial density of states of Fe2SiO4 fayalite up to 30 GPa were presented. Moreover, the evolution of the dielectric function, absorption coefficient (α(ω)), reflectivity (R(ω)), and the real part of the refractive index (n(ω)) at high pressure are also presented.

Partial liquid ventilation reduces fluid filtration of isolated rabbit lungs with acute hydrochloric acid-induced edema.

PubMed

Loer, S A; Tarnow, J

2001-06-01

Hydrochloric acid aspiration increases pulmonary microvascular permeability. The authors tested the hypothesis that partial liquid ventilation has a beneficial effect on filtration coefficients in acute acid-induced lung injury. Isolated blood-perfused rabbit lungs were assigned randomly to one of four groups. Group 1 (n = 6) served as a control group without edema. In group 2 (n = 6), group 3 (n = 6), and group 4 (n = 6), pulmonary edema was induced by intratracheal instillation of hydrochloric acid (0.1 N, 2 ml/kg body weight). Filtration coefficients were determined 30 min after this injury (by measuring loss of perfusate after increase of left atrial pressure). Group 2 lungs were gas ventilated, and group 3 lungs received partial liquid ventilation (15 ml perfluorocarbon/kg body weight). In group 4 lungs, the authors studied the immediate effects of bronchial perfluorocarbon instillation on ongoing filtration. Intratracheal instillation of hydrochloric acid markedly increased filtration coefficients when compared with non-injured control lungs (2.3 +/- 0.7 vs. 0.31 +/- 0.08 ml.min(-1). mmHg(-1).100 g(-1) wet lung weight, P < 0.01). Partial liquid ventilation reduced filtration coefficients of the injured lungs (to 0.9 +/- 0.3 ml.min(-1).mmHg(-1).100 g(-1) wet lung weight, P = 0.022). Neither pulmonary artery nor capillary pressures (determined by simultaneous occlusion of inflow and outflow of the pulmonary circulation) were changed by hydrochloric acid instillation or by partial liquid ventilation. During ongoing filtration, bronchial perfluorocarbon instillation (5 ml/kg body weight) immediately reduced the amount of filtered fluid by approximately 50% (P = 0.027). In the acute phase after acid injury, partial liquid ventilation reduced pathologic fluid filtration. This effect started immediately after bronchial perfluorocarbon instillation and was not associated with changes in mean pulmonary artery, capillary, or airway pressures. The authors suggest that

Application of a High-Throughput Analyzer in Evaluating Solid Adsorbents for Post-Combustion Carbon Capture via Multicomponent Adsorption of CO2, N-2, and H2O

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

Mason, JA; McDonald, TM; Bae, TH

Despite the large number of metal-organic frameworks that have been studied in the context of post-combustion carbon capture, adsorption equilibria of gas mixtures including CO2, N-2, and H2O, which are the three biggest components of the flue gas emanating from a coal- or natural gas-fired power plant, have never been reported. Here, we disclose the design and validation of a high-throughput multicomponent adsorption instrument that can measure equilibrium adsorption isotherms for mixtures of gases at conditions that are representative of an actual flue gas from a power plant. This instrument is used to study 15 different metal-organic frameworks, zeolites, mesoporousmore » silicas, and activated carbons representative of the broad range of solid adsorbents that have received attention for CO2 capture. While the multicomponent results presented in this work provide many interesting fundamental insights, only adsorbents functionalized with alkylamines are shown to have any significant CO2 capacity in the presence of N-2 and H2O at equilibrium partial pressures similar to those expected in a carbon capture process. Most significantly, the amine-appended metal organic framework mmen-Mg-2(dobpdc) (mmen = N,N'-dimethylethylenediamine, dobpdc (4-) = 4,4'-dioxido-3,3'-biphenyldicarboxylate) exhibits a record CO2 capacity of 4.2 +/- 0.2 mmol/g (16 wt %) at 0.1 bar and 40 degrees C in the presence of a high partial pressure of H2O.« less

Application of a high-throughput analyzer in evaluating solid adsorbents for post-combustion carbon capture via multicomponent adsorption of CO2, N2, and H2O.

PubMed

Mason, Jarad A; McDonald, Thomas M; Bae, Tae-Hyun; Bachman, Jonathan E; Sumida, Kenji; Dutton, Justin J; Kaye, Steven S; Long, Jeffrey R

2015-04-15

Despite the large number of metal-organic frameworks that have been studied in the context of post-combustion carbon capture, adsorption equilibria of gas mixtures including CO2, N2, and H2O, which are the three biggest components of the flue gas emanating from a coal- or natural gas-fired power plant, have never been reported. Here, we disclose the design and validation of a high-throughput multicomponent adsorption instrument that can measure equilibrium adsorption isotherms for mixtures of gases at conditions that are representative of an actual flue gas from a power plant. This instrument is used to study 15 different metal-organic frameworks, zeolites, mesoporous silicas, and activated carbons representative of the broad range of solid adsorbents that have received attention for CO2 capture. While the multicomponent results presented in this work provide many interesting fundamental insights, only adsorbents functionalized with alkylamines are shown to have any significant CO2 capacity in the presence of N2 and H2O at equilibrium partial pressures similar to those expected in a carbon capture process. Most significantly, the amine-appended metal organic framework mmen-Mg2(dobpdc) (mmen = N,N'-dimethylethylenediamine, dobpdc (4-) = 4,4'-dioxido-3,3'-biphenyldicarboxylate) exhibits a record CO2 capacity of 4.2 ± 0.2 mmol/g (16 wt %) at 0.1 bar and 40 °C in the presence of a high partial pressure of H2O.

Effects of elevated oxygen and carbon dioxide partial pressures on respiratory function and cognitive performance.

PubMed

Gill, Matthew; Natoli, Michael J; Vacchiano, Charles; MacLeod, David B; Ikeda, Keita; Qin, Michael; Pollock, Neal W; Moon, Richard E; Pieper, Carl; Vann, Richard D

2014-08-15

Hyperoxia during diving has been suggested to exacerbate hypercapnic narcosis and promote unconsciousness. We tested this hypothesis in male volunteers (12 at rest, 10 at 75 W cycle ergometer exercise) breathing each of four gases in a hyperbaric chamber. Inspired Po2 (PiO2 ) was 0.21 and 1.3 atmospheres (atm) without or with an individual subject's maximum tolerable inspired CO2 (PiO2 = 0.055-0.085 atm). Measurements included end-tidal CO2 partial pressure (PetCO2 ), rating of perceived discomfort (RPD), expired minute ventilation (V̇e), and cognitive function assessed by auditory n-back test. The most prominent finding was, irrespective of PetCO2 , that minute ventilation was 8-9 l/min greater for rest or exercise with a PiO2 of 1.3 atm compared with 0.21 atm (P < 0.0001). For hyperoxic gases, PetCO2 was consistently less than for normoxic gases (P < 0.01). For hyperoxic hypercapnic gases, n-back scores were higher than for normoxic gases (P < 0.01), and RPD was lower for exercise but not rest (P < 0.02). Subjects completed 66 hyperoxic hypercapnic trials without incident, but five stopped prematurely because of serious symptoms (tunnel vision, vision loss, dizziness, panic, exhaustion, or near syncope) during 69 normoxic hypercapnic trials (P = 0.0582). Serious symptoms during hypercapnic trials occurred only during normoxia. We conclude serious symptoms with hyperoxic hypercapnia were absent because of decreased PetCO2 consequent to increased ventilation. Copyright © 2014 the American Physiological Society.

Lithium amide (LiNH2) under pressure.

PubMed

Prasad, Dasari L V K; Ashcroft, N W; Hoffmann, Roald

2012-10-11

Static high pressure lithium amide (LiNH(2)) crystal structures are predicted using evolutionary structure search methodologies and intuitive approaches. In the process, we explore the relationship of the structure and properties of solid LiNH(2) to its molecular monomer and dimer, as well as its valence-isoelectronic crystalline phases of methane, water, and ammonia all under pressure. A NaNH(2) (Fddd) structure type is found to be competitive for the ground state of LiNH(2) above 6 GPa with the P = 1 atm I4[overline] phase. Three novel phases emerge at 11 (P4[overline]2(1)m), 13 (P4(2)/ncm), and 46 GPa (P2(1)2(1)2(1)), still containing molecular amide anions, which begin to form N-H···N hydrogen bonds. The P2(1)2(1)2(1) phase remains stable over a wide pressure range. This phase and another Pmc2(1) structure found at 280 GPa have infinite ···(H)N···H···N(H)···H polymeric zigzag chains comprising symmetric N···H···N hydrogen bonds with one NH bond kept out of the chain, an interesting general feature found in many of our high pressure (>280 GPa) LiNH(2) structures, with analogies in high pressure H(2)O-ices. All the predicted low enthalpy LiNH(2) phases are calculated to be enthalpically stable with respect to their elements but resist metallization with increasing pressure up to several TPa. The possibility of Li sublattice melting in the intermediate pressure range structures is raised.

Diagnostic of N2(A) concentration in high velocity nitrogen afterglow at atmospheric pressure

NASA Astrophysics Data System (ADS)

Pointu, Anne-Marie; Mintusov, Evgeny

2009-10-01

An optical emission diagnostic was used to measure N2(A) concentration in a high velocity (1000 cm/s) N2 flowing afterglow of corona discharge at atmospheric pressure, used for biological decontamination. Introducing impurities of NO (<1e-5) we used two well separated and relatively intense lines of NO gamma and beta bands (248nm and 321 nm), easily studied with a low resolution spectrometer. Based on a simplified transport kinetics, the technique is validated using a variation of lines intensity ratios used as coordinates, for numerous experimental points, measured at different axial distances and for different values of NO injected flow. Moreover, it has been demonstrated that N2(A) creation comes from N+N+N2 atom recombination with a global rate around 2e-33 cm^6/s, a result which agrees with literature, as well as N2(A) loss mechanisms were confirmed to go via quenching with O and N atoms. The order of magnitude of obtained N2(A) concentration, about 1e11 cm-3, coincides with the results of direct measurement (by Vegard-Kaplan band), using a spectrometer of better resolution.

Effects of H2 High-pressure Annealing on HfO2/Al2O3/In0.53Ga0.47As Capacitors: Chemical Composition and Electrical Characteristics.

PubMed

Choi, Sungho; An, Youngseo; Lee, Changmin; Song, Jeongkeun; Nguyen, Manh-Cuong; Byun, Young-Chul; Choi, Rino; McIntyre, Paul C; Kim, Hyoungsub

2017-08-29

We studied the impact of H 2 pressure during post-metallization annealing on the chemical composition of a HfO 2 /Al 2 O 3 gate stack on a HCl wet-cleaned In 0.53 Ga 0.47 As substrate by comparing the forming gas annealing (at atmospheric pressure with a H 2 partial pressure of 0.04 bar) and H 2 high-pressure annealing (H 2 -HPA at 30 bar) methods. In addition, the effectiveness of H 2 -HPA on the passivation of the interface states was compared for both p- and n-type In 0.53 Ga 0.47 As substrates. The decomposition of the interface oxide and the subsequent out-diffusion of In and Ga atoms toward the high-k film became more significant with increasing H 2 pressure. Moreover, the increase in the H 2 pressure significantly improved the capacitance‒voltage characteristics, and its effect was more pronounced on the p-type In 0.53 Ga 0.47 As substrate. However, the H 2 -HPA induced an increase in the leakage current, probably because of the out-diffusion and incorporation of In/Ga atoms within the high-k stack.

High-pressure polymorphism of Pb F 2 to 75 GPa

DOE PAGES

Stan, Camelia V.; Dutta, Rajkrishna; White, Claire E.; ...

2016-07-06

Lead fluoride, PbF 2, was investigated experimentally in the laser-heated diamond anvil cell by x-ray diffraction to pressures of 75 GPa at room temperature and to 64.5 GPa and 2430 K, as well as through first-principles density functional theory calculations up to 70 GPa. During room temperature compression, no discontinuous changes in the x-ray diffraction pattern or volume were observed, but the lattice parameters displayed highly anomalous trends between 10-22 GPa with enhanced compressibility along the a direction and reduced or even negative compressibility along b and c. Theoretical calculations of valence electron densities at 22 GPa showed that α-PbFmore » 2 underwent a pressure-induced isosymmetric phase transition to a postcotunnite Co 2Si structure and also revealed the detailed atomic rearrangements associated with the development of an extra Pb-F bond in the high-pressure phase. Our x-ray results and theoretical calculations are consistent with an isosymmetric phase transition smoothly occurring over 10-22 GPa rather than abruptly as previously suggested. The characteristic values for the cell constants a/c and (a+c)/b, which are used to distinguish among cotunnite-, Co 2Si-, and Ni 2In-type phases, require modification based on our results. An equation of state fit yields a bulk modulus, K 0, of 72(3) GPa for the cotunnite-type, and an ambient-pressure volume, V 0, of 182(2)Å 3, and K 0=81(4)GPa for the Co 2Si-type phase when fixing the pressure derivative of the bulk modulus, K 0'=4. Upon heating above 1200 K at pressures at or above 25.9 GPa, PbF 2 partially transformed to the hexagonal Ni 2In-type phase but wholly or partially reverted back to Co 2Si-type phase upon temperature quench. From 43-65 GPa, nearly complete transformation to the Ni 2In-type PbF 2 was observed at high temperature, but the material partially transformed back to the orthorhombic phase upon temperature quench. Our results show that high-pressure behavior of PbF 2 is

The quenching effect of hydrogen on the nitrogen in metastable state in atmospheric-pressure N{sub 2}-H{sub 2} microwave plasma torch

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

Li, Shou-Zhe, E-mail: lisz@dlut.edu.cn; Zhang, Xin; Chen, Chuan-Jie

2014-07-15

The atmospheric-pressure microwave N{sub 2}-H{sub 2} plasma torch is generated and diagnosed by optical emission spectroscopy. It is found that a large amount of N atoms and NH radicals are generated in the plasma torch and the emission intensity of N{sub 2}{sup +} first negative band is the strongest over the spectra. The mixture of hydrogen in nitrogen plasma torch causes the morphology of the plasma discharge to change with appearance that the afterglow shrinks greatly and the emission intensity of N{sub 2}{sup +} first negative band decreases with more hydrogen mixed into nitrogen plasma. In atmospheric-pressure microwave-induced plasma torch,more » the hydrogen imposes a great influence on the characteristics of nitrogen plasma through the quenching effect of the hydrogen on the metastable state of N{sub 2}.« less

Infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide.

PubMed

Kong, Chang Yi; Siratori, Tomoya; Funazukuri, Toshitaka; Wang, Guosheng

2014-10-03

The effects of temperature and density on retention of platinum(II) 2,4-pentanedionate in supercritical fluid chromatography were investigated at temperatures of 308.15-343.15K and pressure range from 8 to 40MPa by the chromatographic impulse response method with curve fitting. The retention factors were utilized to derive the infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide. The determined partial molar volumes were small and positive at high pressures but exhibited very large and negative values in the highly compressible near critical region of carbon dioxide. Copyright © 2014 Elsevier B.V. All rights reserved.

Densification and Electrical Properties of Zinc Oxide Varistors Microwave-Sintered Under Different Oxygen Partial Pressures

NASA Astrophysics Data System (ADS)

Lin, Cong; Wang, Bo; Xu, Zheng; Peng, Hu

2012-11-01

ZnO varistors were prepared by microwave sintering under different oxygen partial pressures. The temperature profile and the densification behavior in different atmospheres were investigated. It was found that the density of ZnO varistors during sintering was the key factor affecting the absorption of microwave energy. The electrical properties, including the nonlinear properties and capacitance-voltage ( C- V) characteristics, were also carefully studied. The results showed that the oxygen partial pressure has significant effects on the electrical properties of ZnO varistors by changing the concentration of defects through a series of reactions involving oxygen during sintering.

Production of NO2/-/ and N2O by nitrifying bacteria at reduced concentrations of oxygen

NASA Technical Reports Server (NTRS)

Goreau, T. J.; Kaplan, W. A.; Wofsy, S. C.; Mcelroy, M. B.; Valois, F. W.; Watson, S. W.

1980-01-01

The influence of oxygen concentration on the production of NO2(-) and N2O by nitrifying marine bacteria of the genus Nitrosomonas is investigated. Pure cultures of the ammonium-oxiding bacteria isolated from the Western Tropical Atlantic Ocean were grown at oxygen partial pressures from 0.005 to 0.2 atm, and concentrations of N2O in the air above the growth medium and dissolved NO2(-) were determined. Decreasing oxygen concentrations are observed to induce a marked decrease in NO2(-) production rates and increase in N2O evolution, leading to an increase of the relative yield of N2O with respect to NO2(-) from 0.3% to nearly 10%. Similar yields of N2O at atmospheric oxygen levels are found for nitrifying bacteria of the genera Nitrosomonas, Nitrosolobus, Nitrosospira and Nitrosococcus, while nitrite-oxydizing bacteria and a dinoflagellate did not produce detectable quantities of N2O. Results support the view that nitrification is a major source of N2O in the environment.

Pressure response of protein backbone structure. Pressure-induced amide 15N chemical shifts in BPTI.

PubMed Central

Akasaka, K.; Li, H.; Yamada, H.; Li, R.; Thoresen, T.; Woodward, C. K.

1999-01-01

The effect of pressure on amide 15N chemical shifts was studied in uniformly 15N-labeled basic pancreatic trypsin inhibitor (BPTI) in 90%1H2O/10%2H2O, pH 4.6, by 1H-15N heteronuclear correlation spectroscopy between 1 and 2,000 bar. Most 15N signals were low field shifted linearly and reversibly with pressure (0.468 +/- 0.285 ppm/2 kbar), indicating that the entire polypeptide backbone structure is sensitive to pressure. A significant variation of shifts among different amide groups (0-1.5 ppm/2 kbar) indicates a heterogeneous response throughout within the three-dimensional structure of the protein. A tendency toward low field shifts is correlated with a decrease in hydrogen bond distance on the order of 0.03 A/2 kbar for the bond between the amide nitrogen atom and the oxygen atom of either carbonyl or water. The variation of 15N shifts is considered to reflect site-specific changes in phi, psi angles. For beta-sheet residues, a decrease in psi angles by 1-2 degrees/2 kbar is estimated. On average, shifts are larger for helical and loop regions (0.553 +/- 0.343 and 0.519 +/- 0.261 ppm/2 kbar, respectively) than for beta-sheet (0.295 +/- 0.195 ppm/2 kbar), suggesting that the pressure-induced structural changes (local compressibilities) are larger in helical and loop regions than in beta-sheet. Because compressibility is correlated with volume fluctuation, the result is taken to indicate that the volume fluctuation is larger in helical and loop regions than in beta-sheet. An important aspect of the volume fluctuation inferred from pressure shifts is that they include motions in slower time ranges (less than milliseconds) in which many biological processes may take place. PMID:10548039

CO2 Solubility in Natural Rhyolitic Melts at High Pressures - Implications for Carbon Flux in Subduction Zones by Sediment Partial Melts

NASA Astrophysics Data System (ADS)

Duncan, M. S.; Dasgupta, R.

2011-12-01

Partial melts of subducting sediments is thought to be a critical agent in carrying trace elements and water to arc basalt source regions. For subduction zones that contain significant amount of carbonates in ocean-floor sediments, sediment melts likely also act as a carrier of CO2. However, the CO2 carrying capacity of natural rhyolitic melts at sub-arc depths remains unconstrained. We conducted experiments on a synthetic composition, similar to average, low-degree experimental partial melt of pelitic sediments. The composition was constructed with reagent grade oxides and carbonates, the source of excess CO2. Experiments were conducted between 1 and 3 GPa at 1200 °C in Au80Pd20 capsules using a piston cylinder apparatus with a half-inch BaCO3 assembly at Rice University. Quench products showed glasses with bubbles, the latter suggesting saturation of the melt with a CO2-rich vapor phase. Oxygen fugacity during the experiments was not strictly controlled but the presence of CO2 bubbles and absence of graphite indicates fO2 above the CCO buffer. Major element concentrations of glasses were measured using EPMA. The CO2 and H2O contents of experimental doubly polished (50-110 μm), bubble-free portions of the glass chips were determined using a Thermo Nicolet Fourier Transform Infrared Spectrometer. Spectra were recorded with a resolution of 4 cm-1, 512 scans, from 650 to 4000 cm-1, under a nitrogen purge to eliminate atmospheric gases. Dissolved volatile concentrations were quantified using the Beer-Lambert law and linear molar absorption coefficients from previous studies [1, 2]. Total dissolved carbon dioxide of experimental glasses was determined from the intensity of the ν3 antisymmetric stretch bands of CO32- at 1430 cm-1 and CO2mol at 2348 cm-1. Dissolved water content of experimental glasses was determined from the intensity of O-H stretching at 3520 cm-1. Estimated total CO2 concentrations at 3 GPa are in the range of 1-2 wt%, for melts with H2O contents

Two Regimes of Bandgap Red Shift and Partial Ambient Retention in Pressure-Treated Two-Dimensional Perovskites

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

Liu, Gang; Kong, Lingping; Guo, Peijun

The discovery of elevated environmental stability in two-dimensional (2D) Ruddlesden–Popper hybrid perovskites represents a significant advance in low-cost, high-efficiency light absorbers. In comparison to 3D counterparts, 2D perovskites of organo-lead-halides exhibit wider, quantum-confined optical bandgaps that reduce the wavelength range of light absorption. Here, we characterize the structural and optical properties of 2D hybrid perovskites as a function of hydrostatic pressure. We observe bandgap narrowing with pressure of 633 meV that is partially retained following pressure release due to an atomic reconfiguration mechanism. We identify two distinct regimes of compression dominated by the softer organic and less compressible inorganic sublattices.more » Our findings, which also include PL enhancement, correlate well with density functional theory calculations and establish structure–property relationships at the atomic scale. These concepts can be expanded into other hybrid perovskites and suggest that pressure/strain processing could offer a new route to improved materials-by-design in applications.« less

Time-dependent middle ear pressure changes under general anaesthesia in children: N2O-O2 mixture versus air-oxygen mixture.

PubMed

Apan, A; Muluk, N Bayar; Güler, S; Budak, B

2013-01-01

The aim of this study was to investigate the effects of N2O-O2 mixture (Inspired O2 30%) on middle ear pressure (MEP) in children compared with the effects of an air-oxygen mixture (Inspired O2 50%). The study included thirty child patients who underwent general anaesthesia for different reasons, with the exception of ENT problems and ear interventions. They were randomly divided into two groups. Group 1 (15 children: 10 male and 5 female) received a N2O-O2 mixture (Inspired O2 30%); and group 2 (15 children: 10 male and 5 female) were given an air-oxygen mixture (Inspired O2 50%). MEP was measured using a portable impedance analyser before the operation (PreO),10 minutes after intubation (10AEn), 30 minutes after intubation (30AEn), 10 minutes before extubation (10BEx), 15 minutes after the operation (PO15), 30 minutes after the operation (PO30), 1 hour after the operation (PO1h) and 6 hours after the operation (PO6h). The pressure and compliance values were the same in groups 1 and 2. The pressure-time graphs for the two groups were different: in Group 2, MEP rose quickly at 10AEn and positive pressure values were seen in the middle ear. MEP then fell rapidly until the end of the surgery and lower and negative pressures (Mean -50 daPa) were observed at PO6h. In Group 1, MEP was elevated at 10AEn and positive pressure was found (but not as high as in Group 2). MEP then fell more slowly. In other words, positive pressure in the middle ear persisted longer and the middle ear was subjected to positive pressure and nitrogen over a longer period. Separate analyses were made in Groups 1 and 2 of pressure differences and of compliance values at eight measurement points using the Friedman test. Differences in pressure values were found to be statistically significant in both Group 1 (p = 0.000) and Group 2 (p = 0.000). In Group 1, all the 10AEn and 30AEn values were significantly higher than the PreO, PO30, PO1h and PO6h values. The 10BEx value was significantly higher

The effect of pH on N2O production under aerobic conditions in a partial nitritation system.

PubMed

Law, Yingyu; Lant, Paul; Yuan, Zhiguo

2011-11-15

Ammonia-oxidising bacteria (AOB) are a major contributor to nitrous oxide (N(2)O) emissions during nitrogen transformation. N(2)O production was observed under both anoxic and aerobic conditions in a lab-scale partial nitritation system operated as a sequencing batch reactor (SBR). The system achieved 55 ± 5% conversion of the 1g NH(4)(+)-N/L contained in a synthetic anaerobic digester liquor to nitrite. The N(2)O emission factor was 1.0 ± 0.1% of the ammonium converted. pH was shown to have a major impact on the N(2)O production rate of the AOB enriched culture. In the investigated pH range of 6.0-8.5, the specific N(2)O production was the lowest between pH 6.0 and 7.0 at a rate of 0.15 ± 0.01 mg N(2)O-N/h/g VSS, but increased with pH to a maximum of 0.53 ± 0.04 mg N(2)O-N/h/g VSS at pH 8.0. The same trend was also observed for the specific ammonium oxidation rate (AOR) with the maximum AOR reached at pH 8.0. A linear relationship between the N(2)O production rate and AOR was observed suggesting that increased ammonium oxidation activity may have promoted N(2)O production. The N(2)O production rate was constant across free ammonia (FA) and free nitrous acid (FNA) concentrations of 5-78 mg NH(3)-N/L and 0.15-4.6 mg HNO(2)-N/L, respectively, indicating that the observed pH effect was not due to changes in FA or FNA concentrations. Copyright © 2011 Elsevier Ltd. All rights reserved.

Noninvasive oxygen partial pressure measurement of human body fluids in vivo using magnetic resonance imaging.

PubMed

Zaharchuk, Greg; Busse, Reed F; Rosenthal, Guy; Manley, Geoffery T; Glenn, Orit A; Dillon, William P

2006-08-01

The oxygen partial pressure (pO2) of human body fluids reflects the oxygenation status of surrounding tissues. All existing fluid pO2 measurements are invasive, requiring either microelectrode/optode placement or fluid removal. The purpose of this study is to develop a noninvasive magnetic resonance imaging method to measure the pO2 of human body fluids. We developed an imaging paradigm that exploits the paramagnetism of molecular oxygen to create quantitative images of fluid oxygenation. A single-shot fast spin echo pulse sequence was modified to minimize artifacts from motion, fluid flow, and partial volume. Longitudinal relaxation rate (R1 = 1/T1) was measured with a time-efficient nonequilibrium saturation recovery method and correlated with pO2 measured in phantoms. pO2 images of human and fetal cerebrospinal fluid, bladder urine, and vitreous humor are presented and quantitative oxygenation levels are compared with prior literature estimates, where available. Significant pO2 increases are shown in cerebrospinal fluid and vitreous following 100% oxygen inhalation. Potential errors due to temperature, fluid flow, and partial volume are discussed. Noninvasive measurements of human body fluid pO2 in vivo are presented, which yield reasonable values based on prior literature estimates. This rapid imaging-based measurement of fluid oxygenation may provide insight into normal physiology as well as changes due to disease or during treatment.

Oxygen partial pressure dependence of thermoelectric power factor in polycrystalline n-type SrTiO3: Consequences for long term stability in thermoelectric oxides

NASA Astrophysics Data System (ADS)

Sharma, Peter A.; Brown-Shaklee, Harlan J.; Ihlefeld, Jon F.

2017-04-01

The Seebeck coefficient and electrical conductivity have been measured as functions of oxygen partial pressure over the range of 10-22 to 10-1 atm at 1173 K for a 10% niobium-doped SrTiO3 ceramic with a grain size comparable to the oxygen diffusion length. Temperature-dependent measurements performed from 320 to 1275 K for as-prepared samples reveal metallic-like conduction and good thermoelectric properties. However, upon exposure to progressively increasing oxygen partial pressure, the thermoelectric power factor decreased over time scales of 24 h, culminating in a three order of magnitude reduction over the entire operating range. Identical measurements on single crystal samples show negligible changes in the power factor so that the instability of ceramic samples is primarily tied to the kinetics of grain boundary diffusion. This work provides a framework for understanding the stability of thermoelectric properties in oxides under different atmospheric conditions. The control of the oxygen atmosphere remains a significant challenge in oxide thermoelectrics.

Partially Hydrolyzed Poly(n-propyl-2-oxazoline): Synthesis, Aqueous Solution Properties, and Preparation of Gene Delivery Systems.

PubMed

Mees, Maarten; Haladjova, Emi; Momekova, Denitsa; Momekov, Georgi; Shestakova, Pavletta S; Tsvetanov, Christo B; Hoogenboom, Richard; Rangelov, Stanislav

2016-11-14

Random copolymers of n-propyl-2-oxazoline and ethylenimine (PPrOx-PEI) were prepared by partial acidic hydrolysis of poly(n-propyl-2-oxazoline) (PPrOx). Dynamic and electrophoretic light scattering and diffusion-ordered NMR spectroscopy were utilized to investigate aqueous solution properties of the copolymers. Above a specific cloud point temperature, well-defined nanoparticles were formed. The latter consisted of a core composed predominantly of PPrOx and a thin positively charged shell from PEI moieties that mediated formation of polyplexes with DNA. The polyplexes were prepared at 65 °C at varying N/P (amine-to-phosphate groups) ratios. They underwent structural changes upon temperature variations 65-25-37 °C depending on N/P. At N/P < 2, the polyplex particles underwent minor changes because of formation of a surface layer of DNA that acted as a barrier and prevented swelling and disintegration of the initial particles. Dramatic rearrangements at N/P ≥ 2 resulting in large swollen microgel particles were overcome by coating of the polyplex particles with a cross-linked polymeric shell. The shell retained the colloidal stability and preserved the physicochemical parameters of the initial polyplex particles while it reduced the high surface potential values. Progressive loss of cytotoxicity upon complexation with DNA and coating of polyplex particles was displayed.

Separating the roles of nitrogen and oxygen in high pressure-induced blood-borne microparticle elevations, neutrophil activation, and vascular injury in mice.

PubMed

Yang, Ming; Bhopale, Veena M; Thom, Stephen R

2015-08-01

An elevation in levels of circulating microparticles (MPs) due to high air pressure exposure and the associated inflammatory changes and vascular injury that occur with it may be due to oxidative stress. We hypothesized that these responses arise due to elevated partial pressures of N2 and not because of high-pressure O2. A comparison was made among high-pressure air, normoxic high-pressure N2, and high-pressure O2 in causing an elevation in circulating annexin V-positive MPs, neutrophil activation, and vascular injury by assessing the leakage of high-molecular-weight dextran in a murine model. After mice were exposed for 2 h to 790 kPa air, there were over 3-fold elevations in total circulating MPs as well as subgroups bearing Ly6G, CD41, Ter119, CD31, and CD142 surface proteins-evidence of neutrophil activation; platelet-neutrophil interaction; and vascular injury to brain, omentum, psoas, and skeletal muscles. Similar changes were found in mice exposed to high-pressure N2 using a gas mixture so that O2 partial pressure was the same as that of ambient air, whereas none of these changes occurred after exposures to 166 kPa O2, the same partial pressure that occurs during high-pressure air exposures. We conclude that N2 plays a central role in intra- and perivascular changes associated with exposure to high air pressure and that these responses appear to be a novel form of oxidative stress. Copyright © 2015 the American Physiological Society.

Influence of oxygen partial pressure on the composition and orientation of strontium-doped lead zirconate titanate thin films.

PubMed

Sriram, S; Bhaskaran, M; du Plessis, J; Short, K T; Sivan, V P; Holland, A S

2009-01-01

The influence of oxygen partial pressure during the deposition of piezoelectric strontium-doped lead zirconate titanate thin films is reported. The thin films have been deposited by RF magnetron sputtering in an atmosphere of high purity argon and oxygen (in the ratio of 9:1), on platinum-coated silicon substrates (heated to 650 degrees C). The influence of oxygen partial pressure is studied to understand the manner in which the stoichiometry of the thin films is modified, and to understand the influence of stoichiometry on the perovskite orientation. This article reports on the results obtained from films deposited at oxygen partial pressures of 1-5 mTorr. The thin films have been studied using a combination of X-ray photoelectron spectroscopy (XPS), glancing angle X-ray diffraction (GA-XRD), and atomic force microscopy (AFM). XPS analysis highlights the marked influence of variations in oxygen pressure during sputtering, observed by variations in oxygen concentration in the thin films, and in some cases by the undesirable decrease in lead concentration in the thin films. GA-XRD is used to study the relative variations in perovskite peak intensities, and has been used to determine the deposition conditions to attain the optimal combination of stoichiometry and orientation. AFM scans show the marked influence of the oxygen partial pressure on the film morphology.

Instrument for stable high temperature Seebeck coefficient and resistivity measurements under controlled oxygen partial pressure

DOE PAGES

Ihlefeld, Jon F.; Brown-Shaklee, Harlan James; Sharma, Peter Anand

2015-04-28

The transport properties of ceramic materials strongly depend on oxygen activity, which is tuned by changing the partial oxygen pressure (pO 2) prior to and during measurement. Within, we describe an instrument for highly stable measurements of Seebeck coefficient and electrical resistivity at temperatures up to 1300 K with controlled oxygen partial pressure. An all platinum construction is used to avoid potential materials instabilities that can cause measurement drift. Two independent heaters are employed to establish a small temperature gradient for Seebeck measurements, while keeping the average temperature constant and avoiding errors associated with pO 2-induced drifts in thermocouple readings.more » Oxygen equilibrium is monitored using both an O 2 sensor and the transient behavior of the resistance as a proxy. A pO 2 range of 10 -25–10 0 atm can be established with appropriate gas mixtures. Seebeck measurements were calibrated against a high purity platinum wire, Pt/Pt–Rh thermocouple wire, and a Bi 2Te3 Seebeck coefficient Standard Reference Material. To demonstrate the utility of this instrument for oxide materials we present measurements as a function of pO 2 on a 1 % Nb-doped SrTiO 3 single crystal, and show systematic changes in properties consistent with oxygen vacancy defect chemistry. Thus, an approximately 11% increase in power factor over a pO 2 range of 10 -19–10 -8 atm at 973 K for the donor-doped single crystals is observed.« less

Applying Chemical Potential and Partial Pressure Concepts to Understand the Spontaneous Mixing of Helium and Air in a Helium-Inflated Balloon

ERIC Educational Resources Information Center

Jee-Yon Lee; Hee-Soo Yoo; Jong Sook Park; Kwang-Jin Hwang; Jin Seog Kim

2005-01-01

The spontaneous mixing of helium and air in a helium-inflated balloon is described in an experiment in which the partial pressure of the gases in the balloon are determined from the mole factions and the total pressure measured in the balloon. The results described provide a model for teaching concepts of partial pressure, chemical potential, and…

Effect of Nitrogen Content on Physical and Chemical Properties of TiN Thin Films Prepared by DC Magnetron Sputtering with Supported Discharge

NASA Astrophysics Data System (ADS)

Kavitha, A.; Kannan, R.; Gunasekhar, K. R.; Rajashabala, S.

2017-10-01

Amorphous titanium nitride (TiN) thin films have been prepared on silicon (Si) and glass substrates by direct-current (DC) reactive magnetron sputtering with a supported discharge (triode). Nitrogen gas (N2) at partial pressure of 0.3 Pa, 0.4 Pa, 0.5 Pa, and 0.6 Pa was used to prepare the TiN thin films, maintaining total pressure of argon and N2 of about 0.7 Pa. The chemical, microstructural, optical, and electrical properties of the TiN thin films were systematically studied. Presence of different phases of Ti with nitrogen (N), oxygen (O2), and carbon (C) elements was revealed by x-ray photoelectron spectroscopy characterization. Increase in the nitrogen pressure from 0.3 Pa to 0.6 Pa reduced the optical bandgap of the TiN thin film from 2.9 eV to 2.7 eV. Photoluminescence study showed that TiN thin film deposited at N2 partial pressure of 0.3 Pa exhibited three shoulder peaks at 330 nm, 335 nm, and 340 nm, which disappeared when the sample was deposited with N2 partial pressure of 0.6 Pa. Increase in the nitrogen content decreased the electrical resistivity of the TiN thin film from 3200 μΩ cm to 1800 μΩ cm. Atomic force microscopy studies of the TiN thin films deposited with N2 partial pressure of 0.6 Pa showed a uniform surface pattern associated with accumulation of fine grains. The results and advantages of this method of preparing TiN thin films are also reported.

The change of steel surface chemistry regarding oxygen partial pressure and dew point

NASA Astrophysics Data System (ADS)

Norden, Martin; Blumenau, Marc; Wuttke, Thiemo; Peters, Klaus-Josef

2013-04-01

By investigating the surface state of a Ti-IF, TiNb-IF and a MnCr-DP after several series of intercritical annealing, the impact of the annealing gas composition on the selective oxidation process is discussed. On behalf of the presented results, it can be concluded that not the general oxygen partial pressure in the annealing furnace, which is a result of the equilibrium reaction of water and hydrogen, is the main driving force for the selective oxidation process. It is shown that the amounts of adsorbed gases at the strip surface and the effective oxygen partial pressure resulting from the adsorbed gases, which is mainly dependent on the water content of the annealing furnace, is driving the selective oxidation processes occurring during intercritical annealing. Thus it is concluded, that for industrial applications the dew point must be the key parameter value for process control.

Modulation of paraquat toxicity by beta-carotene at low oxygen partial pressure in chicken embryo fibroblasts.

PubMed

Lawlor, S M; O'Brien, N M

1997-01-01

The efficiency with which beta-carotene protects against oxidative stress in chicken embryo fibroblasts (CEF) at low O2 partial pressures was assessed. Primary cultures of CEF were grown at low O2 partial pressures and oxidatively stressed by exposure to paraquat (PQ). Activities of the antioxidant enzymes superoxide dismutase (EC 1.15.1.1; SOD), catalase (EC 1.11.1.6; CAT) and glutathione peroxidase (EC 1.11.1.9; GSH-Px) were measured as indices of oxidative stress. CEF incubated with 0.25-1.0 mM-PQ for 18 h exhibited increased SOD and CAT activities compared with non-PQ-treated control cells (P < 0.001). No cytotoxicity as indicated by lactate dehydrogenase (EC 1.1.1.27; LDH) release was observed at PQ concentrations below 2.0 mM. Incorporation of added beta-carotene into 0.25 mM-PQ-treated cells prevented the PQ-induced increases in SOD and CAT, and activities were similar to those seen in non-PQ-treated control cells. GSH-Px activity decreased relative to its control value on exposure to 0.25 mM-PQ and beta-carotene prevented this decrease in a dose-dependent manner. The proportion of LDH released from the CEF treated with beta-carotene remained below the control value of 2.5% at all times.

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.

Gain and saturation energy measurements in low pressure longitudinally excited N 2-lasers

NASA Astrophysics Data System (ADS)

Ghoreyshi, S.; Rahimian, K.; Hariri, Akbar

2004-08-01

A flat-plate Blumlein circuit has been used for operating a low pressure longitudinally excited oscillator-amplifier N 2-laser at 14 kV input voltage (LE-LE type). For investigating the effect of the excitation length on the laser performances, various amplifiers made of glass tubes of different lengths ranging from 15.5 to 35 cm with 4 mm inner bore diameters have been used. The measurements have been carried out for the laser parameters: small signal gain, and saturation energy density; and the laser beam divergence. Details of our measurements are presented. The results of our measurements have also been compared with the reported values of laser parameters in TE-TEA and LE N 2-laser configurations.

Photochemical removal of NO(2) by using 172-nm Xe(2) excimer lamp in N(2) or air at atmospheric pressure.

PubMed

Tsuji, Masaharu; Kawahara, Masashi; Noda, Kenji; Senda, Makoto; Sako, Hiroshi; Kamo, Naohiro; Kawahara, Takashi; Kamarudin, Khairul Sozana Nor

2009-03-15

Photochemical removal of NO(2) in N(2) or air (5-20% O(2)) mixtures was studied by using 172-nm Xe(2) excimer lamps to develop a new simple photochemical aftertreatment technique of NO(2) in air at atmospheric pressure without using any catalysts. When a high power lamp (300 mW/cm(2)) was used, the conversion of NO(2) (200-1000 ppm) to N(2) and O(2) in N(2) was >93% after 1 min irradiation, whereas that to N(2)O(5), HNO(3), N(2), and O(2) in air (10% O(2)) was 100% after 5s irradiation in a batch system. In a flow system, about 92% of NO(2) (200 ppm) in N(2) was converted to N(2) and O(2), whereas NO(2) (200-400 ppm) in air (20% O(2)) could be completely converted to N(2)O(5), HNO(3), N(2), and O(2) at a flow rate of 1l/min. It was found that NO could also be decomposed to N(2) and O(2) under 172-nm irradiation, though the removal rate is slower than that of NO(2) by a factor of 3.8. A simple model analysis assuming a consecutive reaction NO(2)-->NO-->N+O indicated that 86% of NO(2) is decomposed directly into N+O(2) and the rest is dissociated into NO+O under 172-nm irradiation. These results led us to conclude that the present technique is a new promising catalyst-free photochemical aftertreatment method of NO(2) in N(2) and air in a flow system.

Oxygen supply in aquatic ectotherms: partial pressure and solubility together explain biodiversity and size patterns.

PubMed

Verberk, Wilco C E P; Bilton, David T; Calosi, Piero; Spicer, John I

2011-08-01

Aquatic ectotherms face the continuous challenge of capturing sufficient oxygen from their environment as the diffusion rate of oxygen in water is 3 x 10(5) times lower than in air. Despite the recognized importance of oxygen in shaping aquatic communities, consensus on what drives environmental oxygen availability is lacking. Physiologists emphasize oxygen partial pressure, while ecologists emphasize oxygen solubility, traditionally expressing oxygen in terms of concentrations. To resolve the question of whether partial pressure or solubility limits oxygen supply in nature, we return to first principles and derive an index of oxygen supply from Fick's classic first law of diffusion. This oxygen supply index (OSI) incorporates both partial pressure and solubility. Our OSI successfully explains published patterns in body size and species across environmental clines linked to differences in oxygen partial pressure (altitude, organic pollution) or oxygen solubility (temperature and salinity). Moreover, the OSI was more accurately and consistently related to these ecological patterns than other measures of oxygen (oxygen saturation, dissolved oxygen concentration, biochemical oxygen demand concentrations) and similarly outperformed temperature and altitude, which covaried with these environmental clines. Intriguingly, by incorporating gas diffusion rates, it becomes clear that actually more oxygen is available to an organism in warmer habitats where lower oxygen concentrations would suggest the reverse. Under our model, the observed reductions in aerobic performance in warmer habitats do not arise from lower oxygen concentrations, but instead through organismal oxygen demand exceeding supply. This reappraisal of how organismal thermal physiology and oxygen demands together shape aerobic performance in aquatic ectotherms and the new insight of how these components change with temperature have broad implications for predicting the responses of aquatic communities to

SGLT2 inhibitors: their potential reduction in blood pressure.

PubMed

Maliha, George; Townsend, Raymond R

2015-01-01

The sodium glucose co-transporter 2 (SGLT2) inhibitors represent a promising treatment option for diabetes and its common comorbidity, hypertension. Emerging data suggests that the SGLT2 inhibitors provide a meaningful reduction in blood pressure, although the precise mechanism of the blood pressure drop remains incompletely elucidated. Based on current data, the blood pressure reduction is partially due to a combination of diuresis, nephron remodeling, reduction in arterial stiffness, and weight loss. While current trials are underway focusing on cardiovascular endpoints, the SGLT2 inhibitors present a novel treatment modality for diabetes and its associated hypertension as well as an opportunity to elucidate the pathophysiology of hypertension in diabetes. Copyright © 2015 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.

Detecting and Constraining N2 Abundances in Planetary Atmospheres Using Collisional Pairs

NASA Astrophysics Data System (ADS)

Schwieterman, Edward W.; Robinson, Tyler D.; Meadows, Victoria S.; Misra, Amit; Domagal-Goldman, Shawn

2015-09-01

Characterizing the bulk atmosphere of a terrestrial planet is important for determining surface pressure and potential habitability. Molecular nitrogen (N2) constitutes the largest fraction of Earth's atmosphere and is likely to be a major constituent of many terrestrial exoplanet atmospheres. Due to its lack of significant absorption features, N2 is extremely difficult to remotely detect. However, N2 produces an N2-N2 collisional pair, (N2)2, which is spectrally active. Here we report the detection of (N2)2 in Earth's disk-integrated spectrum. By comparing spectra from NASA's EPOXI mission to synthetic spectra from the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional spectral Earth model, we find that (N2)2 absorption produces a ˜35% decrease in flux at 4.15 μm. Quantifying N2 could provide a means of determining bulk atmospheric composition for terrestrial exoplanets and could rule out abiotic O2 generation, which is possible in rarefied atmospheres. To explore the potential effects of (N2)2 in exoplanet spectra, we used radiative transfer models to generate synthetic emission and transit transmission spectra of self-consistent N2-CO2-H2O atmospheres, and analytic N2-H2 and N2-H2-CO2 atmospheres. We show that (N2)2 absorption in the wings of the 4.3 μm CO2 band is strongly dependent on N2 partial pressures above 0.5 bar and can significantly widen this band in thick N2 atmospheres. The (N2)2 transit transmission signal is up to 10 ppm for an Earth-size planet with an N2-dominated atmosphere orbiting within the habitable zone of an M5V star and could be substantially larger for planets with significant H2 mixing ratios.

Measurement of alveolar oxygen partial pressure in the rat lung using Carr-Purcell-Meiboom-Gill spin-spin relaxation times of hyperpolarized 3He and 129Xe at 74 mT.

PubMed

Kraayvanger, Ryan J; Bidinosti, Christopher P; Dominguez-Viqueira, William; Parra-Robles, Juan; Fox, Matthew; Lam, Wilfred W; Santyr, Giles E

2010-11-01

Regional measurement of alveolar oxygen partial pressure can be obtained from the relaxation rates of hyperpolarized noble gases, (3) He and (129) Xe, in the lungs. Recently, it has been demonstrated that measurements of alveolar oxygen partial pressure can be obtained using the spin-spin relaxation rate (R(2) ) of (3) He at low magnetic field strengths (<0.1 T) in vivo. R(2) measurements can be achieved efficiently using the Carr-Purcell-Meiboom-Gill pulse sequence. In this work, alveolar oxygen partial pressure measurements based on Carr-Purcell-Meiboom-Gill R(2) values of hyperpolarized (3) He and (129) Xe in vitro and in vivo in the rat lung at low magnetic field strength (74 mT) are presented. In vitro spin-spin relaxivity constants for (3) He and (129) Xe were determined to be (5.2 ± 0.6) × 10(-6) Pa(-1) sec(-1) and (7.3 ± 0.4) × 10(-6) Pa(-1) s(-1) compared with spin-lattice relaxivity constants of (4.0 ± 0.4) × 10(-6) Pa(-1) s(-1) and (4.3 ± 1.3) × 10(-6) Pa(-1) s(-1), respectively. In vivo experimental measurements of alveolar oxygen partial pressure using (3) He in whole rat lung show good agreement (r(2) = 0.973) with predictions based on lung volumes and ventilation parameters. For (129) Xe, multicomponent relaxation was observed with one component exhibiting an increase in R(2) with decreasing alveolar oxygen partial pressure. Copyright © 2010 Wiley-Liss, Inc.

Flight test evaluation of an RAF high altitude partial pressure protective assembly

NASA Technical Reports Server (NTRS)

Ashworth, G. R.; Putnam, T. W.; Dana, W. J.; Enevoldson, E. K.; Winter, W. R.

1979-01-01

A partial pressure suit was evaluated during tests in an F-104 and F-15 as a protective garment for emergency descents. The garment is an pressure jerkin and modified anti-g suit combined with an oronasal mask. The garment can be donned and doffed at the aircraft to minimize thermal buildup. The oronasal mask was favored by the pilots due to its immobility on the face during high g-loading. The garment was chosen to provide optimum dexterity for the pilot, which is not available in a full pressure suit, while protecting the pilot at altitudes up to 18,288 meters, during a cabin decompression, and subsequent aircraft descent. During cabin decompressions in the F-104 and F-15, cabin pressure altitude was measured at various aircraft angles of attack, Mach numbers, and altitudes to determine the effect of the aerodynamic slipstream on the cabin altitude.

Cryogenically formed prestressed composite fiber-metal structures for O2/N2 high pressure gas tanks.

NASA Technical Reports Server (NTRS)

Gleich, D.

1971-01-01

Demonstration of high-structural-performance ARDEFORM cryoformed 301 stainless-steel glass-fiber-reinforced (GFR) vessels by room temperature tests of 13 1/2-in. diam spheres. Tests verified that the structural performance of ARDEFORM spherical GFR vessels not only exceeded that of all metal construction, but also bettered previous GFR experimental results by 50%. Achievement of essentially the full strength of fiberglass in a spherical wrap pattern was again verified. Significant weight advantages for this construction are projected for O2/N2 high-pressure gas tanks for Space Shuttle environmental control/life support system missions.

Transport properties of nonelectrolyte liquid mixtures—III. Viscosity coefficients for n-octane, n-dodecane, and equimolar mixtures of n-octane + n-dodecane and n-hexane + n-dodecane from 25 to 100°C at pressures up to the freezing pressure or 500 MPa

NASA Astrophysics Data System (ADS)

Dymond, J. H.; Robertson, J.; Isdale, J. D.

1981-06-01

Viscosity coefficients measured with an estimated accuracy of 2% using a new design of self-centering falling body viscometer are reported for n-octane, n-dodecane, and equimolar mixtures of n-octane + n-dodecane and n-hexane + n-dodecane at 25, 50, 75, and 100°C at pressures up to the freezing pressure or 500 MPa. The data for a given composition at different temperatures and pressures are very satisfactorily correlated by a plot of ή, defined as 104ηV2/3/( MT)1/2 in the cgs system of units or, generally, 9.118×107ηV2/3/( MRT)1/2, versus log V', where V' = V · V 0( T R)/ V 0( T) and V 0 represents the close-packed volume at temperature T and reference temperature T R. The experimental results are fitted, generally well within the estimated uncertainty, by the equation 10765_2004_Article_BF00503937_TeX2GIFE1.gif ln η ' = - 1.0 + {BV_0 }/{V - V_0 } , where B and V 0 are temperature and composition dependent. Values of B and V 0 for the mixtures are simply related to values for the pure liquids. The binary mixing rule of Grunberg and Nissan is investigated. Values of the mixing parameter G are positive, tend to increase with increases in pressure, and also increase with increases in difference in carbon number of the two pure components.

First-principles study on the structural, elastic and electronic properties of Ti4N3 and Ti6N5 under high pressure

NASA Astrophysics Data System (ADS)

Yang, Ruike; Chai, Bao; Zhu, Chuanshuai; Wei, Qun; Du, Zheng

2017-12-01

The structural, elastic and electronic properties of Ti4N3 and Ti6N5 have been systematically studied by first-principles calculations based on density functional theory (DFT) with generalized gradient approximation (GGA) and local density approximation (LDA). Basic physical properties for Ti4N3 and Ti6N5, such as the lattice constants, the bulk modulus, shear modulus, and elastic constants are calculated. The results show that Ti4N3 and Ti6N5 are mechanically stable under ambient pressure. The phonon dispersion spectra are researched throughout the Brillouin zone via the linear response approach as implemented in the CASTEP code, which indicate the optimized structures are stable dynamically. The Young’s modulus E and Poisson’s ratios ν are also determined within the framework of the Voigt-Reuss-Hill approximation. The analyses show that Ti4N3 is more ductile than Ti6N5 at the same pressure and ductility increases as the pressure increases. Moreover, the anisotropies of the Ti4N3 and Ti6N5 are discussed by the Young’s modulus at different directions, and the results indicate that the anisotropy of the two Ti-N compounds is obvious. The total density of states (TDOS) and partial density of states (PDOS) show that the TDOS of TiN, Ti4N3 and Ti6N5 originate mainly from Ti “d” and N “p” states. The results show that Ti4N3 and Ti6N5 present semimetal character. Pressure makes the level range of DOS significantly extended, for TiN, Ti4N3 and Ti6N5. The TDOS decreases with the pressure rise, at Fermi level.

Pressure-induced depression of synaptic transmission in the cerebellar parallel fibre synapse involves suppression of presynaptic N-type Ca2+ channels.

PubMed

Etzion, Y; Grossman, Y

2000-11-01

High pressure induces CNS hyperexcitability while markedly depressing synaptic transmitter release. We studied the effect of pressure (up to 10.1 MPa) on the parallel fibre (PF) synaptic response in biplanar cerebellar slices of adult guinea pigs. Pressure mildly reduced the PF volley amplitude and to a greater extent depressed the excitatory field postsynaptic potential (fPSP). The depression of the PF volley was noted even at supramaximal stimulus intensities, indicating an effect of pressure on the amplitude of the action potential in each axon. Low concentrations of TTX mimicked the effects of pressure on the PF volley without affecting the fPSP. Application omega-conotoxin GVIA (omega-CgTx) reduced the synaptic efficacy by 34.3+/-2.7%. However, in the presence of omega-CgTx the synaptic depression at pressure was significantly reduced. Reduced Ca2+ entry by application of Cd2+ or low [Ca2+]o did not have a similar influence on the effects of pressure. Application of omega-AGA IVA, omega-AGA TK and Funnel-web spider toxin did not affect the synaptic response in concentrations that usually block P-type Ca2+ channels, whilst the N/P/Q-type blocker omega-conotoxin MVIIC reduced the response to 52.7+/-5.0% indicating the involvement of Q-type channels and R-type channels in the non-N-type fraction of Ca2+ entry. The results demonstrate that N-type Ca2+ channels play a crucial role in the induction of PF synaptic depression at pressure. This finding suggests a coherent mechanism for the induction of CNS hyperexcitability at pressure.

A flowing liquid test system for assessing the linearity and time-response of rapid fibre optic oxygen partial pressure sensors.

PubMed

Chen, R; Hahn, C E W; Farmery, A D

2012-08-15

The development of a methodology for testing the time response, linearity and performance characteristics of ultra fast fibre optic oxygen sensors in the liquid phase is presented. Two standard medical paediatric oxygenators are arranged to provide two independent extracorporeal circuits. Flow from either circuit can be diverted over the sensor under test by means of a system of rapid cross-over solenoid valves exposing the sensor to an abrupt change in oxygen partial pressure, P O2. The system is also capable of testing the oxygen sensor responses to changes in temperature, carbon dioxide partial pressure P CO2 and pH in situ. Results are presented for a miniature fibre optic oxygen sensor constructed in-house with a response time ≈ 50 ms and a commercial fibre optic sensor (Ocean Optics Foxy), when tested in flowing saline and stored blood. Copyright © 2012 Elsevier B.V. All rights reserved.

Effects of elevated artificial pneumoperitoneum pressure on invasive blood pressure and levels of blood gases.

PubMed

Hypolito, Octavio; Azevedo, João Luiz; Gama, Fernanda; Azevedo, Otavio; Miyahira, Susana Abe; Pires, Oscar César; Caldeira, Fabiana Alvarenga; Silva, Thamiris

2014-01-01

to evaluate the clinical, hemodynamic, gas analysis and metabolic repercussions of high transient pressures of pneumoperitoneum for a short period of time to ensure greater security for introduction of the first trocar. sixty-seven patients undergoing laparoscopic procedures were studied and randomly distributed in P12 group: n=30 (intraperitoneal pressure [IPP] 12mmHg) and P20 group: n=37 (IPP of 20mmHg). Mean arterial pressure (MAP) was evaluated by catheterization of the radial artery; and through gas analysis, pH, partial pressure of oxygen (PaO2), partial pressure of CO2 (PaCO2), bicarbonate (HCO3) and alkalinity (BE) were evaluated. These parameters were measured in both groups at time zero before pneumoperitoneum (TP0); at time 1 (TP1) when IPP reaches 12mmHg in both groups; at time 2 (TP2) after five min with IPP=12mmHg in P12 and after 5min with IPP=20mmHg at P20; and at time 3 (TP3) after 10min with IPP=12mmHg in P12 and with return of IPP from 20 to 12mmHg, starting 10min after TP1 in P20. Different values from those considered normal for all parameters assessed, or the appearance of atypical organic phenomena, were considered as clinical changes. there were statistically significant differences in P20 group in MAP, pH, HCO3 and BE, but within normal limits. No clinical and pathological changes were observed. high and transient intra-abdominal pressure causes changes in MAP, pH, HCO3 and BE, but without any clinical impact on the patient. Copyright © 2014 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.

Sensor for measuring hydrogen partial pressure in parabolic trough power plant expansion tanks

NASA Astrophysics Data System (ADS)

Glatzmaier, Greg C.; Cooney, Daniel A.

2017-06-01

The National Renewable Energy Laboratory and Acciona Energy North America are working together to design and implement a process system that provides a permanent solution to the issue of hydrogen buildup at parabolic trough power plants. We are pursuing a method that selectively removes hydrogen from the expansion tanks that serve as reservoirs for the heat transfer fluid (HTF) that circulates in the collector field and power block components. Our modeling shows that removing hydrogen from the expansion tanks at a design rate reduces and maintains dissolved hydrogen in the circulating HTF to a selected target level. Our collaborative work consists of several tasks that are needed to advance this process concept to a development stage, where it is ready for implementation at a commercial power plant. Our main effort is to design and evaluate likely process-unit operations that remove hydrogen from the expansion tanks at a specified rate. Additionally, we designed and demonstrated a method and instrumentation to measure hydrogen partial pressure and concentration in the expansion-tank headspace gas. We measured hydrogen partial pressure in the headspace gas mixture using a palladium-alloy membrane, which is permeable exclusively to hydrogen. The membrane establishes a pure hydrogen gas phase that is in equilibrium with the hydrogen in the gas mixture. We designed and fabricated instrumentation, and demonstrated its effectiveness in measuring hydrogen partial pressures over a range of three orders of magnitude. Our goal is to install this instrument at the Nevada Solar One power plant and to demonstrate its effectiveness in measuring hydrogen levels in the expansion tanks under normal plant operating conditions.

Sensor for Measuring Hydrogen Partial Pressure in Parabolic Trough Power Plant Expansion Tanks

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

Glatzmaier, Greg C.; Cooney, Daniel A.

The National Renewable Energy Laboratory and Acciona Energy North America are working together to design and implement a process system that provides a permanent solution to the issue of hydrogen buildup at parabolic trough power plants. We are pursuing a method that selectively removes hydrogen from the expansion tanks that serve as reservoirs for the heat transfer fluid (HTF) that circulates in the collector field and power block components. Our modeling shows that removing hydrogen from the expansion tanks at a design rate reduces and maintains dissolved hydrogen in the circulating HTF to a selected target level. Our collaborative workmore » consists of several tasks that are needed to advance this process concept to a development stage, where it is ready for implementation at a commercial power plant. Our main effort is to design and evaluate likely process-unit operations that remove hydrogen from the expansion tanks at a specified rate. Additionally, we designed and demonstrated a method and instrumentation to measure hydrogen partial pressure and concentration in the expansion-tank headspace gas. We measured hydrogen partial pressure in the headspace gas mixture using a palladium-alloy membrane, which is permeable exclusively to hydrogen. The membrane establishes a pure hydrogen gas phase that is in equilibrium with the hydrogen in the gas mixture. We designed and fabricated instrumentation, and demonstrated its effectiveness in measuring hydrogen partial pressures over a range of three orders of magnitude. Our goal is to install this instrument at the Nevada Solar One power plant and to demonstrate its effectiveness in measuring hydrogen levels in the expansion tanks under normal plant operating conditions.« less

Partial dissolution of ACQ-treated wood in lithium chloride/N-methyl-2-pyrrolidinone: Separation of copper from potential lignocellulosic feedstocks

Treesearch

Thomas L. Eberhardt; Stan Lebow; Karen G. Reed

2012-01-01

A cellulose solvent system based on lithium chloride (LiCl) in N-methyl-2-pyrrolidinone (NMP) was used to assess the merits of partial dissolutions of coarsely ground wood samples. Alkaline Copper Quaternary (ACQ)-treated pine wood was of particular interest for treatment given the potential to generate a copper- rich stream apart from solid and/or liquid...

The structural phase diagram and oxygen equilibrium partial pressure of YBa 2Cu 3O 6+ x studied by neutron powder diffraction and gas volumetry

NASA Astrophysics Data System (ADS)

Andersen, N. H.; Lebech, B.; Poulsen, H. F.

1990-12-01

An experimental technique based on neutron powder diffraction and gas volumetry is presented and used to study the structural phase diagram of YBa 2Cu 3O 6+ x under equilibrium conditions in an extended part of ( x, T)-phase (0.15< x<0.92 and 25° C< T<725°C). Our experimental observations lend strong support to a recent two-dimensional anisotropic next-nearest-neighbour Ising model calculation (the ASYNNNI model) of the basal plane oxygen ordering based of first principle interaction parameters. Simultaneous measurements of the oxygen equilibrium partial pressure show anomalies, one of which proves the thermodynamic stability of the orthorhombic OII double cell structure. Striking similarity with predictions of recent model calculations support that another anomaly may be interpreted to result from local one-dimensional fluctuations in the distribution of oxygen atoms in the basal plane of tetragonal YBCO. Our pressure data also indicate that x=0.92 is a maximum obtainable oxygen concentration for oxygen pressures below 760 Torr.

Impact of partial nitritation degree and C/N ratio on simultaneous Sludge Fermentation, Denitrification and Anammox process.

PubMed

Wang, Bo; Peng, Yongzhen; Guo, Yuanyuan; Yuan, Yue; Zhao, Mengyue; Wang, Shuying

2016-11-01

This study presents a novel process (i.e. PN/SFDA) to remove nitrogen from low C/N domestic wastewater. The process mainly involves two reactors, a pre-Sequencing Batch Reactor for partial nitritation (termed as PN-SBR) and an anoxic reactor for integrated Denitrification and Anammox with carbon sources produced from Sludge Fermentation (termed as SFDA). During long-term Runs, NO2(-)/NH4(+) ratio (i.e. NO2(-)-N/NH4(+)-N calculated by mole) in the PN-SBR effluent was gradually increased from 0.2 to 37 by extending aerobic duration, meaning that partial nitritation turning to full nitritation could be achieved. Impact of partial nitritation degree on SFDA process was investigated and the result showed that, NO2(-)/NH4(+) ratios between 2 and 10 were appropriate for the co-existence of denitrification and anammox together in the SFDA reactor, and denitrification instead of anammox contributed greater for nitrogen removal. Further batch tests indicated that anammox collaborated well with denitrification at low C/N (1.0 in this study). Copyright © 2016 Elsevier Ltd. All rights reserved.

Contrasting effects of lower body positive pressure on upper airways resistance and partial pressure of carbon dioxide in men with heart failure and obstructive or central sleep apnea.

PubMed

Kasai, Takatoshi; Motwani, Shveta S; Yumino, Dai; Gabriel, Joseph M; Montemurro, Luigi Taranto; Amirthalingam, Vinoban; Floras, John S; Bradley, T Douglas

2013-03-19

This study sought to test the effects of rostral fluid displacement from the legs on transpharyngeal resistance (Rph), minute volume of ventilation (Vmin), and partial pressure of carbon dioxide (PCO2) in men with heart failure (HF) and either obstructive (OSA) or central sleep apnea (CSA). Overnight rostral fluid shift relates to severity of OSA and CSA in men with HF. Rostral fluid displacement may facilitate OSA if it shifts into the neck and increases Rph, because pharyngeal obstruction causes OSA. Rostral fluid displacement may also facilitate CSA if it shifts into the lungs and induces reflex augmentation of ventilation and reduces PCO2, because a decrease in PCO2 below the apnea threshold causes CSA. Men with HF were divided into those with mainly OSA (obstructive-dominant, n = 18) and those with mainly CSA (central-dominant, n = 10). While patients were supine, antishock trousers were deflated (control) or inflated for 15 min (lower body positive pressure [LBPP]) in random order. LBPP reduced leg fluid volume and increased neck circumference in both obstructive- and central-dominant groups. However, in contrast to the obstructive-dominant group in whom LBPP induced an increase in Rph, a decrease in Vmin, and an increase in PCO2, in the central-dominant group, LBPP induced a reduction in Rph, an increase in Vmin, and a reduction in PCO2. These findings suggest mechanisms by which rostral fluid shift contributes to the pathogenesis of OSA and CSA in men with HF. Rostral fluid shift could facilitate OSA if it induces pharyngeal obstruction, but could also facilitate CSA if it augments ventilation and lowers PCO2. Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

[Partial pressure of CO2 and CO2 degassing fluxes of Huayuankou and Xiaolangdi Station affected by Xiaolangdi Reservoir].

PubMed

Zhang, Yong-ling; Yang, Xiao-lin; Zhang, Dong

2015-01-01

According to periodic sampling analysis per month in Xiaolangdi station and Huayuankou station from November 2011 to October 2012, combined with continuous sampling analysis of Xiaolangdi Reservoir during runoff and sediment control period in 2012, partial pressure of CO2 (pCO2) in surface water were calculated based on Henry's Law, pCO2 features and air-water CO2 degassing fluxes of Huayuankou station and Xiaolangdi station affected by Xiaolangdi Reservoir were studied. The results were listed as follows, when Xiaolangdi Reservoir operated normally, pCO2 in surface water of Xiaolangdi station and Huayuankou station varied from 82 to 195 Pa and from 99 to 228 Pa, moreover, pCO2 in surface water from July to September were distinctly higher than those in other months; meanwhile, pCO, in surface water from Huayuankou station were higher than that from Xiaolangdi station. During runoff and sediment control period of Xiaolangdi Reservoir, two hydrological stations commonly indicated that pCO2 in surface water during water draining were obviously lower than those during sediment releasing. Whether in the period of normal operation or runoff and sediment control, pCO2 in surface water had positive relations to DIC content in two hydrological stations. Since the EpCO,/AOU value was higher than the theoretical value of 0. 62, the biological aerobic respiration effect had distinct contribution to pCO2. Throughout the whole year, air-water CO2 degassing fluxes from Xiaolangdi station and Huayuankou station were 0.486 p.mol (m2 s) -l and 0.588 pmol (m2 x s)(-1) respectively; When Xiaolangdi Reservoir operated normally, air-water CO, degassing fluxes in Huayuankou station were higher than that in Xiaolangdi station; during runoff and sediment control from Xiaolangdi Reservoir, two hydrological stations had one observation result in common, namely, air-water CO2 degassing fluxes in the period of water draining were obviously lower than that in the period of sediment releasing.

Analysis of the CO 2 Chemisorption in Li 5FeO 4, a New High Temperature CO 2 Captor Material. Effect of the CO 2 and O 2 Partial Pressures

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

Lara-García, Hugo A.; Sanchez-Camacho, Pedro; Duan, Yuhua

Pentalithium ferrite (Li 5FeO 4) was tested in this paper as possible CO 2 captor, both by theoretical calculations and experimental measurements. The pristine Li 5FeO 4 compound with orthorhombic structure was synthesized via solid-state reaction and it was structural and microstructurally characterized. Later, sample was heat-treated at temperatures from room temperature to 900 °C under different CO 2 or CO 2–O 2 atmospheres. Li 5FeO 4 exhibits excellent CO 2 chemisorption abilities with a capture capacity about 12.9 mmol/g, which is outstanding in comparison to other previously reported ceramic captors. This material is able to react with CO 2more » from 200 °C to approximately 715 °C showing a high kinetic of reaction even at CO 2 partial pressure values as low as 0.2. Finally and additionally, results suggest that oxygen addition does enhance the CO 2 chemisorption on Li 5FeO 4 at temperatures below 700 °C, although oxygen addition seems to favor the desorption process at higher temperatures.« less

Analysis of the CO 2 Chemisorption in Li 5FeO 4, a New High Temperature CO 2 Captor Material. Effect of the CO 2 and O 2 Partial Pressures

DOE PAGES

Lara-García, Hugo A.; Sanchez-Camacho, Pedro; Duan, Yuhua; ...

2017-01-23

Pentalithium ferrite (Li 5FeO 4) was tested in this paper as possible CO 2 captor, both by theoretical calculations and experimental measurements. The pristine Li 5FeO 4 compound with orthorhombic structure was synthesized via solid-state reaction and it was structural and microstructurally characterized. Later, sample was heat-treated at temperatures from room temperature to 900 °C under different CO 2 or CO 2–O 2 atmospheres. Li 5FeO 4 exhibits excellent CO 2 chemisorption abilities with a capture capacity about 12.9 mmol/g, which is outstanding in comparison to other previously reported ceramic captors. This material is able to react with CO 2more » from 200 °C to approximately 715 °C showing a high kinetic of reaction even at CO 2 partial pressure values as low as 0.2. Finally and additionally, results suggest that oxygen addition does enhance the CO 2 chemisorption on Li 5FeO 4 at temperatures below 700 °C, although oxygen addition seems to favor the desorption process at higher temperatures.« less

Low tritium partial pressure permeation system for mass transport measurement in lead lithium eutectic

DOE PAGES

Pawelko, R. J.; Shimada, M.; Katayama, K.; ...

2015-11-28

This paper describes a new experimental system designed to investigate tritium mass transfer properties in materials important to fusion technology. Experimental activities were carried out at the Safety and Tritium Applied Research (STAR) facility located at the Idaho National Laboratory (INL). The tritium permeation measurement system was developed as part of the Japan/US TITAN collaboration to investigate tritium mass transfer properties in liquid lead lithium eutectic (LLE) alloy. The experimental system is configured to measure tritium mass transfer properties at low tritium partial pressures. Initial tritium permeation scoping tests were conducted on a 1 mm thick α-Fe plate to determinemore » operating parameters and to validate the experimental technique. A second series of permeation tests was then conducted with the α-Fe plate covered with an approximately 8.5 mm layer of liquid lead lithium eutectic alloy (α-Fe/LLE). We present preliminary tritium permeation data for α-Fe and α-Fe/LLE at temperatures between 400 and 600°C and at tritium partial pressures between 1.7E-3 and 2.5 Pa in helium. Preliminary results for the α-Fe plate and α-Fe/LLE indicate that the data spans a transition region between the diffusion-limited regime and the surface-limited regime. In conclusion, additional data is required to determine the existence and range of a surface-limited regime.« less

Electronic and chemical structure of the H 2O/GaN(0001) interface under ambient conditions

DOE PAGES

Zhang, Xueqiang; Ptasinska, Sylwia

2016-04-25

We employed ambient pressure X-ray photoelectron spectroscopy to investigate the electronic and chemical properties of the H 2O/GaN(0001) interface under elevated pressures and/or temperatures. A pristine GaN(0001) surface exhibited upward band bending, which was partially flattened when exposed to H 2O at room temperature. However, the GaN surface work function was slightly reduced due to the adsorption of molecular H 2O and its dissociation products. At elevated temperatures, a negative charge generated on the surface by a vigorous H 2O/GaN interfacial chemistry induced an increase in both the surface work function and upward band bending. We tracked the dissociative adsorptionmore » of H 2O onto the GaN(0001) surface by recording the core-level photoemission spectra and obtained the electronic and chemical properties at the H 2O/GaN interface under operando conditions. In conclusion, our results suggest a strong correlation between the electronic and chemical properties of the material surface, and we expect that their evolutions lead to significantly different properties at the electrolyte/ electrode interface in a photoelectrochemical solar cell.« less

Effect of oxygen partial pressure on the density of antiphase boundaries in Fe3O4 thin films on Si(100)

NASA Astrophysics Data System (ADS)

Singh, Suraj Kumar; Husain, Sajid; Kumar, Ankit; Chaudhary, Sujeet

2018-02-01

Polycrystalline Fe3O4 thin films were grown on Si(100) substrate by reactive DC sputtering at different oxygen partial pressures PO2 for controlling the growth associated density of antiphase boundaries (APBs). The micro-Raman analyses were performed to study the structural and electronic properties in these films. The growth linked changes in the APBs density are probed by electron-phonon coupling strength (λ) and isothermal magnetization measurements. The estimated values of λ are found to vary from 0.39 to 0.56 with the increase in PO2 from 2.2 × 10-5 to 3.0 × 10-5 Torr, respectively. The saturation magnetization (saturation field) values are found to increase (decrease) from 394 (5.9) to 439 (3.0) emu/cm3 (kOe) with the increase in PO2 . The sharp Verwey transition (∼120 K), low saturation field, high saturation magnetization and low value of λ (comparable to the bulk value ∼0.51) clearly affirm the negligible amount of APBs in the high oxygen partial pressure deposited thin films.

Effect of Electroacupuncture on Transcutaneous Oxygen Partial Pressure During Hyperbaric Oxygen Therapy in Healthy Individuals.

PubMed

Qu, Lan; Ye, Yong; Li, Chunfeng; Gao, Guangkai

2015-01-01

The goal of hyperbaric oxygen therapy (HBOT) is to increase the oxygen (O₂) supply to the body significantly. Because of the toxic side effects and complications of hyperbaric oxygen (HBO₂), the environmental pressure and treatment time must be restricted. The research team hypothesized that other therapies administered during HBOT could safely improve the value of the arterial oxygen partial pressure (PaO₂) during HBOT and improve its therapeutic effect. The study intended to investigate whether electroacupuncture (EA) while receiving HBOT had a greater effect for healthy individuals than HBOT or EA alone or EA combined with normobaric pure oxygen (pure O₂). The research team designed a randomized, controlled trial. The study was performed in the Department of Hyperbaric Medicine at the No. 401 Hospital of the People's Liberation Army in Qingdao, China. A total of 81 volunteers were recruited. After thorough physical examination and laboratory testing, 21 volunteers were excluded from the study. Participants included 60 healthy volunteers. Participants were randomly assigned to 1 of 4 groups of 15 participants each: (1) an HBOT group, (2) an EA group, (3) an EA During HBOT group, and (4) an EA Combined With Pure O₂group. Because at the current technology level a blood gas analyzer cannot test PaO₂during HBOT, transcutaneous oxygen partial pressure (PtcO₂) of the participants was tested instead. Before, during, and after EA, variations in PtcO₂were monitored in each group. For the EA During HBOT group, (1) the increase in PtcO₂during EA was significantly greater than that observed for the other 3 groups (P > .05). The EA During HBOT method provided improvements in the efficacy, safety, and tolerability of HBOT, and the study's results partially demonstrated the accuracy of the research team's hypothesis that EA therapy applied during HBOT could safely improve the value of PtcO₂(PaO₂) during HBOT and produce a greater therapeutic effect.

Comparison of exogenous surfactant therapy, mechanical ventilation with high end-expiratory pressure and partial liquid ventilation in a model of acute lung injury.

PubMed

Hartog, A; Vazquez de Anda, G F; Gommers, D; Kaisers, U; Verbrugge, S J; Schnabel, R; Lachmann, B

1999-01-01

We have compared three treatment strategies, that aim to prevent repetitive alveolar collapse, for their effect on gas exchange, lung mechanics, lung injury, protein transfer into the alveoli and surfactant system, in a model of acute lung injury. In adult rats, the lungs were ventilated mechanically with 100% oxygen and a PEEP of 6 cm H2O, and acute lung injury was induced by repeated lung lavage to obtain a PaO2 value < 13 kPa. Animals were then allocated randomly (n = 12 in each group) to receive exogenous surfactant therapy, ventilation with high PEEP (18 cm H2O), partial liquid ventilation or ventilation with low PEEP (8 cm H2O) (ventilated controls). Blood-gas values were measured hourly. At the end of the 4-h study, in six animals per group, pressure-volume curves were constructed and bronchoalveolar lavage (BAL) was performed, whereas in the remaining animals lung injury was assessed. In the ventilated control group, arterial oxygenation did not improve and protein concentration of BAL and conversion of active to non-active surfactant components increased significantly. In the three treatment groups, PaO2 increased rapidly to > 50 kPa and remained stable over the next 4 h. The protein concentration of BAL fluid increased significantly only in the partial liquid ventilation group. Conversion of active to non-active surfactant components increased significantly in the partial liquid ventilation group and in the group ventilated with high PEEP. In the surfactant group and partial liquid ventilation groups, less lung injury was found compared with the ventilated control group and the group ventilated with high PEEP. We conclude that although all three strategies improved PaO2 to > 50 kPa, the impact on protein transfer into the alveoli, surfactant system and lung injury differed markedly.

Brain tissue partial pressure of oxygen predicts the outcome of severe traumatic brain injury under mild hypothermia treatment.

PubMed

Sun, Hongtao; Zheng, Maohua; Wang, Yanmin; Diao, Yunfeng; Zhao, Wanyong; Wei, Zhengjun

2016-01-01

The aim of this study was to investigate the clinical significance and changes of brain tissue partial pressure of oxygen (PbtO2) in the course of mild hypothermia treatment (MHT) for treating severe traumatic brain injury (sTBI). There were 68 cases with sTBI undergoing MHT. PbtO2, intracranial pressure (ICP), jugular venous oxygen saturation (SjvO2), and cerebral perfusion pressure (CPP) were continuously monitored, and clinical outcomes were evaluated using the Glasgow Outcome Scale score. Of 68 patients with sTBI, PbtO2, SjvO2, and CPP were obviously increased, but decreased ICP level was observed throughout the MHT. PbtO2 and ICP were negatively linearly correlated, while there was a positive linear correlation between PbtO2 and SjvO2. Monitoring CPP and SjvO2 was performed under normal circumstances, and a large proportion of patients were detected with low PbtO2. Decreased PbtO2 was also found after MHT. Continuous PbtO2 monitoring could be introduced to evaluate the condition of regional cerebral oxygen metabolism, thereby guiding the clinical treatment and predicting the outcome.

Real-Time Monitoring of Singlet Oxygen and Oxygen Partial Pressure During the Deep Photodynamic Therapy In Vitro.

PubMed

Li, Weitao; Huang, Dong; Zhang, Yan; Liu, Yangyang; Gu, Yueqing; Qian, Zhiyu

2016-09-01

Photodynamic therapy (PDT) is an effective noninvasive method for the tumor treatment. The major challenge in current PDT research is how to quantitatively evaluate therapy effects. To our best knowledge, this is the first time to combine multi-parameter detection methods in PDT. More specifically, we have developed a set of system, including the high-sensitivity measurement of singlet oxygen, oxygen partial pressure and fluorescence image. In this paper, the detection ability of the system was validated by the different concentrations of carbon quantum dots. Moreover, the correlation between singlet oxygen and oxygen partial pressure with laser irradiation was observed. Then, the system could detect the signal up to 0.5 cm tissue depth with 660 nm irradiation and 1 cm tissue depth with 980 nm irradiation by using up-conversion nanoparticles during PDT in vitro. Furthermore, we obtained the relationship among concentration of singlet oxygen, oxygen partial pressure and tumor cell viability under certain conditions. The results indicate that the multi-parameter detection system is a promising asset to evaluate the deep tumor therapy during PDT. Moreover, the system might be potentially used for the further study in biology and molecular imaging.

Effect of systemic nitric oxide synthase inhibition on optic disc oxygen partial pressure in normoxia and in hypercapnia.

PubMed

Petropoulos, Ioannis K; Pournaras, Jean-Antoine C; Stangos, Alexandros N; Pournaras, Constantin J

2009-01-01

To investigate the effect of systemic nitric oxide synthase (NOS) inhibition on optic disc oxygen partial pressure (PO(2)) in normoxia and hypercapnia. Intervascular optic disc PO(2) was measured in 12 anesthetized minipigs by using oxygen-sensitive microelectrodes placed <50 microm from the optic disc. PO(2) was measured continuously during 10 minutes under normoxia, hyperoxia (100% O(2)), carbogen breathing (95% O(2), 5% CO(2)), and hypercapnia (increased inhaled CO(2)). Measurements were repeated after intravenous injection of N(omega)-nitro-L-arginine methyl ester (L-NAME) 100 mg/kg. Intravenous L-arginine 100 mg/kg was subsequently given to three animals. Before L-NAME injection, an increase was observed in optic disc PO(2) during hypercapnia (DeltaPO(2) = 3.2 +/- 1.7 mm Hg; 18%; P = 0.001) and carbogen breathing (DeltaPO(2) = 12.8 +/- 5.1 mm Hg; 69%; P < 0.001). Optic disc PO(2) in normoxia remained stable for 30 minutes after L-NAME injection (4% decrease from baseline; P > 0.1), despite a 21% increase of mean arterial pressure. Optic disc PO(2) increase under hypercapnia was blunted after L-NAME injection (DeltaPO(2) = 0.6 +/- 1.1 mm Hg; 3%; P > 0.1), and this effect was reversible by L-arginine. Moreover, L-NAME reduced the response to carbogen by 29% (DeltaPO(2) = 9.1 +/- 4.4 mm Hg; 49%; P = 0.01 versus before L-NAME). The response to hyperoxia was not affected. Whereas systemic NOS inhibition did not affect optic disc PO(2) in normoxia, a blunting effect was noted on the CO(2)-induced optic disc PO(2) increase. Nitric oxide appears to mediate the hypercapnic optic disc PO(2) increase.

Development of high-resolution n(2) coherent anti-stokes Raman scattering for measuring pressure, temperature, and density in high-speed gas flows.

PubMed

Woodmansee, M A; Lucht, R P; Dutton, J C

2000-11-20

Mean and instantaneous measurements of pressure, temperature, and density have been acquired in an optically accessible gas cell and in the flow field of an underexpanded sonic jet by use of the high-resolution N(2) coherent anti-Stokes Raman scattering (CARS) technique. This nonintrusive method resolves the pressure- and temperature-sensitive rotational transitions of the nu = 0 ? 1 N(2) Q-branch to within Domega = 0.10 cm(-1). To extract thermodynamic information from the experimental spectra, theoretical spectra, generated by a N(2) spectral modeling program, are fit to the experimental spectra in a least-squares manner. In the gas cell, the CARS-measured pressures compare favorably with transducer-measured pressures. The precision and accuracy of the single-shot CARS pressure measurements increase at subatmospheric conditions. Along the centerline of the underexpanded jet, the agreement between the mean CARS P/T/rho measurements and similar quantities extracted from a Reynolds-averaged Navier-Stokes computational fluid dynamic simulation is generally excellent. This CARS technique is able to capture the low-pressure and low-temperature conditions of the M = 3.4 flow entering the Mach disk, as well as the subsonic conditions immediately downstream of this normal shock.

Correlation between mobility collapse and carbon impurities in Si-doped GaN grown by low pressure metalorganic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Kaess, Felix; Mita, Seiji; Xie, Jingqiao; Reddy, Pramod; Klump, Andrew; Hernandez-Balderrama, Luis H.; Washiyama, Shun; Franke, Alexander; Kirste, Ronny; Hoffmann, Axel; Collazo, Ramón; Sitar, Zlatko

2016-09-01

In the low doping range below 1 × 1017 cm-3, carbon was identified as the main defect attributing to the sudden reduction of the electron mobility, the electron mobility collapse, in n-type GaN grown by low pressure metalorganic chemical vapor deposition. Secondary ion mass spectroscopy has been performed in conjunction with C concentration and the thermodynamic Ga supersaturation model. By controlling the ammonia flow rate, the input partial pressure of Ga precursor, and the diluent gas within the Ga supersaturation model, the C concentration in Si-doped GaN was controllable from 6 × 1019 cm-3 to values as low as 2 × 1015 cm-3. It was found that the electron mobility collapsed as a function of free carrier concentration, once the Si concentration closely approached the C concentration. Lowering the C concentration to the order of 1015 cm-3 by optimizing Ga supersaturation achieved controllable free carrier concentrations down to 5 × 1015 cm-3 with a peak electron mobility of 820 cm2/V s without observing the mobility collapse. The highest electron mobility of 1170 cm2/V s was obtained even in metalorganic vapor deposition-grown GaN on sapphire substrates by optimizing growth parameters in terms of Ga supersaturation to reduce the C concentration.

Studies on the structural stability of Co2P2O7 under pressure

NASA Astrophysics Data System (ADS)

Wang, W. P.; Pang, H.; Jin, M. L.; Shen, X.; Yao, Y.; Wang, Y. G.; Li, Y. C.; Li, X. D.; Jin, C. Q.; Yu, R. C.

2018-05-01

The crystal structural evolution of Co2P2O7 was studied by using in situ high pressure angle dispersive x-ray diffraction with synchrotron radiation. The results demonstrate that the α phase of Co2P2O7 goes through a partially irreversible structural transformation to β phase under pressure. The pressure is conductive to reduce the longest Cosbnd O bond length of the α phase, and then more uniform Cosbnd O bonds and regular hexagonal arrangement of CoO6 octahedra of the β phase are favored. According to the Birch-Murnaghan equation, the fitted bulk modulus B0 is 158.1(±5.6) GPa for α phase and 276.5(±6.5) GPa for β phase. Furthermore, the first-principles calculations show that these two phases of Co2P2O7 have almost equal total energies, and also have similar band structures and spin-polarized density of states at their ground states. This may be the reason why these two phases of Co2P2O7 can coexist in the pressure released state. It is found that the band gap energies decrease with increasing pressure for both phases.

Partial N=2 to N=1 supersymmetry breaking and gravity deformed chiral rings.

NASA Astrophysics Data System (ADS)

David, Justin R.; Gava, Edi; Narain, K. S.

2004-06-01

We present a derivation of the chiral ring relations, arising in Script N = 1 gauge theories in the presence of (anti-)self-dual background gravitational field Galphabetagamma and graviphoton field strength Falphabeta. These were previously considered in the literature in order to prove the relation between gravitational F-terms in the gauge theory and coefficients of the topological expansion of the related matrix integral. We consider the spontaneous breaking of Script N = 2 to Script N = 1 supergravity coupled to vector- and hyper-multiplets, and take a rigid limit which keeps a non-trivial Galphabetagamma and Falphabeta with a finite supersymmetry breaking scale. We derive the resulting effective, global, Script N = 1 theory and show that the chiral ring relations are just a consequence of the standard Script N = 2 supergravity Bianchi identities. We can also obtain models with matter in different representations and in particular quiver theories. We also show that, in the presence of non-trivial Falphabeta, consistency of the Konishi-anomaly loop equations with the chiral ring relations, demands that the gauge kinetic function and the superpotential, a priori unrelated for an Script N = 1 theory, should be derived from a prepotential, indicating an underlying Script N = 2 structure.

Adsorption of 2-propanol on ice probed by ambient pressure X-ray photoelectron spectroscopy

DOE PAGES

Newberg, John T.; Bluhm, Hendrik

2015-08-18

The interaction of 2-propanol with ice was examined via ambient pressure X-ray photoelectron spectroscopy (APXPS), a surface sensitive technique that probes the adsorbed 2-propanol directly with submonolayer resolution. Isothermal uptake experiments were performed on vapor deposited ice at 227 K in the presence of the equilibrium water vapor pressure of 0.05 Torr and 2-propanol partial pressures ranging from 5 × 10 -5 to 2 × 10 -3 Torr. The C 1s APXPS spectra of adsorbed 2-propanol showed two characteristic peaks associated with the C OH alcohol group and C Me methyl groups in a 1 : 2 ratio, respectively. Coveragemore » increased with 2-propanol partial pressure and followed first order Langmuir kinetics with a Langmuir constant of K = 6.3 × 10 3 Torr -1. The 1 : 2 ratio of C OH : C Me remained constant with increasing coverage, indicating there is no chemical reaction upon adsorption. The observed Langmuir kinetics using APXPS is consistent with previous observations of other small chain alcohols via indirect adsorption methods using, e.g., Knudsen cell and coated wall flow tube reactors.« less

Method for sensing and measuring a concentration or partial pressure of a reactant used in a redox reaction

DOEpatents

Findl, E.

1984-12-21

A method for sensing or measuring the partial pressure or concentration of an electroactive species used in conjunction with an electrolyte, the method being characterized by providing a constant current between an anode and a cathode of an electrolyte-containing cell, while measuring changes in voltage that occur between either the anode and cathode or between a reference electrode and one of the main electrodes of the cell, thereby to determine the concentration or partial pressure of the electro-active species as a function of said measured voltage changes. The method of the invention can be practiced using either a cell having only an anode and a cathode, or using a cell having an anode and a cathode in combination with a reference electrode. Accurate measurements of small concentrations or partial pressures of electro-active species are obtainable with the method of the invention, by using constant currents of only a few microamperes between the anode and cathode of the cell, while the concentration-determining voltage is measured.

Oxygen Partial Pressure Is a Rate-Limiting Parameter for Cell Proliferation in 3D Spheroids Grown in Physioxic Culture Condition

PubMed Central

Gomes, Aurélie; Guillaume, Ludivine; Grimes, David Robert; Fehrenbach, Jérôme; Lobjois, Valérie; Ducommun, Bernard

2016-01-01

The in situ oxygen partial pressure in normal and tumor tissues is in the range of a few percent. Therefore, when studying cell growth in 3D culture systems, it is essential to consider how the physiological oxygen concentration, rather than the one in the ambient air, influences the proliferation parameters. Here, we investigated the effect of reducing oxygen partial pressure from 21% to 5% on cell proliferation rate and regionalization in a 3D tumor spheroid model. We found that 5% oxygen concentration strongly inhibited spheroid growth, changed the proliferation gradient and reduced the 50% In Depth Proliferation index (IDP50), compared with culture at 21% oxygen. We then modeled the oxygen partial pressure profiles using the experimental data generated by culturing spheroids in physioxic and normoxic conditions. Although hypoxia occurred at similar depth in spheroids grown in the two conditions, oxygen partial pressure was a major rate-limiting factor with a critical effect on cell proliferation rate and regionalization only in spheroids grown in physioxic condition and not in spheroids grown at atmospheric normoxia. Our findings strengthen the need to consider conducting experiment in physioxic conditions (i.e., tissue normoxia) for proper understanding of cancer cell biology and the evaluation of anticancer drugs in 3D culture systems. PMID:27575790

Oxygen Partial Pressure Is a Rate-Limiting Parameter for Cell Proliferation in 3D Spheroids Grown in Physioxic Culture Condition.

PubMed

Gomes, Aurélie; Guillaume, Ludivine; Grimes, David Robert; Fehrenbach, Jérôme; Lobjois, Valérie; Ducommun, Bernard

2016-01-01

The in situ oxygen partial pressure in normal and tumor tissues is in the range of a few percent. Therefore, when studying cell growth in 3D culture systems, it is essential to consider how the physiological oxygen concentration, rather than the one in the ambient air, influences the proliferation parameters. Here, we investigated the effect of reducing oxygen partial pressure from 21% to 5% on cell proliferation rate and regionalization in a 3D tumor spheroid model. We found that 5% oxygen concentration strongly inhibited spheroid growth, changed the proliferation gradient and reduced the 50% In Depth Proliferation index (IDP50), compared with culture at 21% oxygen. We then modeled the oxygen partial pressure profiles using the experimental data generated by culturing spheroids in physioxic and normoxic conditions. Although hypoxia occurred at similar depth in spheroids grown in the two conditions, oxygen partial pressure was a major rate-limiting factor with a critical effect on cell proliferation rate and regionalization only in spheroids grown in physioxic condition and not in spheroids grown at atmospheric normoxia. Our findings strengthen the need to consider conducting experiment in physioxic conditions (i.e., tissue normoxia) for proper understanding of cancer cell biology and the evaluation of anticancer drugs in 3D culture systems.

Pressure dependence of the electro-optic response function in partially exposed polymer dispersed ferroelectric liquid crystals

NASA Technical Reports Server (NTRS)

Parmar, D. S.; Holmes, H. K.

1993-01-01

Ferroelectric liquid crystals in a new configuration, termed partially exposed polymer dispersed ferroelectric liquid crystal (PEPDFLC), respond to external pressures and demonstrate pressure-induced electro-optic switching response. When the PEPDFLC thin film is sandwiched between two transparent conducting electrodes, one a glass plate and the other a flexible sheet such as polyvenylidene fluoride, the switching characteristics of the thin film are a function of the pressure applied to the flexible transparent electrode and the bias voltage across the electrodes. Response time measurements reveal a linear dependence of the change in electric field with external pressure.

Emergent ferromagnetism and T -linear scattering in USb 2 at high pressure [Emergent ferromagnetism in USb 2 under pressure

DOE PAGES

Jeffries, Jason R.; Stillwell, Ryan L.; Weir, Samuel T.; ...

2016-05-09

The material USb 2 is a correlated, moderately heavy-electron compound within the uranium dipnictide (UX 2) series. It is antiferromagnetic with a relatively high transition temperature T N = 204K and a large U-U separation. While the uranium atoms in the lighter dipnictides are considered to be localized, those of USb 2 exhibit hybridization and itineracy, promoting uncertainty as to the continuity of the magnetic order within the UX 2. We have explored the evolution of the magnetic order by employing magnetotransport measurements as a function of pressure and temperature. We find that the T N in USb 2 ismore » enhanced, moving towards that of its smaller sibling UAs 2. But, long before reaching a T N as high as UAs 2, the antiferromagnetism of USb 2 is abruptly destroyed in favor of another magnetic ground state. We identify this pressure-induced ground state as being ferromagnetic based on the appearance of a strong anomalous Hall effect in the transverse resistance in magnetic field. At last with pressure, this emergent ferromagnetic state is suppressed and ultimately destroyed in favor of a non-Fermi-liquid ground state.« less

Emergent ferromagnetism and T -linear scattering in USb 2 at high pressure [Emergent ferromagnetism in USb 2 under pressure

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

Jeffries, Jason R.; Stillwell, Ryan L.; Weir, Samuel T.

The material USb 2 is a correlated, moderately heavy-electron compound within the uranium dipnictide (UX 2) series. It is antiferromagnetic with a relatively high transition temperature T N = 204K and a large U-U separation. While the uranium atoms in the lighter dipnictides are considered to be localized, those of USb 2 exhibit hybridization and itineracy, promoting uncertainty as to the continuity of the magnetic order within the UX 2. We have explored the evolution of the magnetic order by employing magnetotransport measurements as a function of pressure and temperature. We find that the T N in USb 2 ismore » enhanced, moving towards that of its smaller sibling UAs 2. But, long before reaching a T N as high as UAs 2, the antiferromagnetism of USb 2 is abruptly destroyed in favor of another magnetic ground state. We identify this pressure-induced ground state as being ferromagnetic based on the appearance of a strong anomalous Hall effect in the transverse resistance in magnetic field. At last with pressure, this emergent ferromagnetic state is suppressed and ultimately destroyed in favor of a non-Fermi-liquid ground state.« less

Suppression of diamagnetism by neutrals pressure in partially ionized, high-beta plasma

NASA Astrophysics Data System (ADS)

Shinohara, Shunjiro; Kuwahara, Daisuke; Yano, Kazuki; Fruchtman, Amnon

2016-12-01

Suppression of diamagnetism in a partially ionized plasma with high beta was experimentally investigated by the use of Langmuir and Hall sensor probes, focusing on a neutrals pressure effect. The plasma beta, which is the ratio of plasma to vacuum magnetic pressures, varied from ˜1% to >100% while the magnetic field varied from ˜120 G to ˜1 G. Here, a uniform magnetized argon plasma was operated mostly in an inductive mode, using a helicon plasma source of the Large Helicon Plasma Device [S. Shinohara et al., Phys. Plasmas 16, 057104 (2009)] with a diameter of 738 mm and an axial length of 4860 mm. Electron density varied from 5 × 1015 m-3 to <3 × 1018 m-3, while an argon fill pressure was varied from ˜0.02 Pa to 0.75 Pa as well as the magnetic field mentioned above, with the fixed radio frequency (rf) and power of 7 MHz and ˜3.5 kW, respectively. The observed magnetic field reduction rate, a decrease of the magnetic field divided by the vacuum one, was up to 18%. However, in a certain parameter regime, where the product of ion and electron Hall terms is a key parameter, the measured diamagnetic effect was smaller than that expected by the plasma beta. This suppressed diamagnetism is explained by the neutrals pressure replacing magnetic pressure in balancing plasma pressure. Diamagnetism is weakened if neutrals pressure is comparable to the plasma pressure and if the coupling of plasma and neutrals pressures by ion-neutral collisions is strong enough.

[Peroxynitrite effect on the haemoglobin oxygen affinity in vitro in presence of different partial pressure of carbon dioxide].

PubMed

Stepuro, T L; Zinchuk, V V

2011-08-01

Peroxynitrite (ONOO-) besides its toxic possesses regulatory action that includes the modulation of oxygen binding properties of blood. The aim of this work was to estimate ONOO- effect on the haemoglobin oxygen affinity (HOA) in vitro in presence of different partial pressure of carbon dioxide (CO2). The ONOO- presence in venous blood in conditions of hypercapnia induced oxyhaemoglobin dissociation curve shift leftward while in hypocapnic conditions the result of a different character was obtained. The revealed effect of ONOO- is realized, possibly, through various modifications ofhaemoglobin whose formation is dependent on the CO2 pressure. The ONOO- influences the HOA in different manner that can be important in regulation of blood oxygenation in lungs and maintenance of oxygen consumption in tissues.

Influence of polymeric microspheres on the myocardial oxygen partial pressure in the beating heart of pigs.

PubMed

Hiebl, B; Mrowietz, C; Lee, S; Braune, S; Knaut, M; Lendlein, A; Franke, R P; Jung, F

2011-07-01

Injection of labeled microspheres is an established method in animal models to analyze the capillary organ blood flow at different time points. However, the microspheres can lead to stenoses of the capillary lumen, which might affect tissue oxygen supply. Our study aimed to investigate the influence of repeated injections of microspheres into the left coronary artery on the tissue oxygen partial pressure (pO(2)) in the downstream supplied myocardium of Göttingen minipigs. Tests (n=6 pigs each) were performed with two differently sized microspheres (ø=10 ± 0.1 μm (M10) or ø=15 ± 0.15 μm (M15)) from polystyrene. The pO(2) was measured in the midmyocardium of the left and right ventricle for 6 min continuously after each of five injections (1 × 10(6) microspheres each). There was a time laps of 12 min between each injection. In addition, the influence of the carrier solution was analyzed solely in the identical time frame. pO(2) decreased significantly in the myocardial area supplied by the ramus interventricularis paraconalis after injection of M15 microspheres. In contrast, the application of the M10 microspheres did not change the myocardial pO(2). This finding suggests to use microspheres with diameters not exceeding 10 μm for the coronary blood flow assessment. Copyright © 2011 Elsevier Inc. All rights reserved.

Theoretical study of the partial molar volume change associated with the pressure-induced structural transition of ubiquitin

PubMed Central

Imai, Takashi; Ohyama, Shusaku; Kovalenko, Andriy; Hirata, Fumio

2007-01-01

The partial molar volume (PMV) change associated with the pressure-induced structural transition of ubiquitin is analyzed by the three-dimensional reference interaction site model (3D-RISM) theory of molecular solvation. The theory predicts that the PMV decreases upon the structural transition, which is consistent with the experimental observation. The volume decomposition analysis demonstrates that the PMV reduction is primarily caused by the decrease in the volume of structural voids in the protein, which is partially canceled by the volume expansion due to the hydration effects. It is found from further analysis that the PMV reduction is ascribed substantially to the penetration of water molecules into a specific part of the protein. Based on the thermodynamic relation, this result implies that the water penetration causes the pressure-induced structural transition. It supports the water penetration model of pressure denaturation of proteins proposed earlier. PMID:17660257

Theoretical study of the partial molar volume change associated with the pressure-induced structural transition of ubiquitin.

PubMed

Imai, Takashi; Ohyama, Shusaku; Kovalenko, Andriy; Hirata, Fumio

2007-09-01

The partial molar volume (PMV) change associated with the pressure-induced structural transition of ubiquitin is analyzed by the three-dimensional reference interaction site model (3D-RISM) theory of molecular solvation. The theory predicts that the PMV decreases upon the structural transition, which is consistent with the experimental observation. The volume decomposition analysis demonstrates that the PMV reduction is primarily caused by the decrease in the volume of structural voids in the protein, which is partially canceled by the volume expansion due to the hydration effects. It is found from further analysis that the PMV reduction is ascribed substantially to the penetration of water molecules into a specific part of the protein. Based on the thermodynamic relation, this result implies that the water penetration causes the pressure-induced structural transition. It supports the water penetration model of pressure denaturation of proteins proposed earlier.

Partial Pressures for Several In-Se Compositions from Optical Absorbance of the Vapor

NASA Technical Reports Server (NTRS)

Brebrick, R. F.; Su, Ching-Hua

2001-01-01

The optical absorbance of the vapor phase over various In-Se compositions between 33.3-60.99 at.% Se and 673-1418 K was measured and used to obtain the partial pressures of Se2(g) and In2Se(g). The results are in agreement with silica Bourdon gauge measurements for compositions between 50-61 at.%, but significantly higher than those from Knudsen cell and simultaneous Knudsen-torsion cell measurements. It is found that 60.99 at.% Se lies outside the sesquiselenide homogeneity range and 59.98 at.% Se lies inside and is the congruently melting composition. The Gibbs energy of formation of the liquid from its pure liquid elements between 1000-1300 K is essentially independent of temperature and falls between -36 to -38 kJ per g atomic weight for 50 and 56% Se at 1200 and 1300 K.

The relationship between cognitive function and arterial partial pressure O2 in patients with COPD: A meta-analysis.

PubMed

Wen, Xia-Hong; Li, Yan; Han, Dong; Sun, Li; Ren, Ping-Xiao; Ren, Dan

2018-01-01

The high incidence of cognition disorders in chronic obstructive pulmonary disease (COPD) patients represents a main focus in public health field recently. Thus, we tried to explore relationship between cognitive function and arterial partial pressure O2 (PaO2) in patients with COPD as assessed by Mini-mental State Examination (MMSE) and/or Montreal Cognitive Assessment (MoCA). Medical and scientific literature databases, such as Web of Science, PubMed, Cochrane Library, China National Knowledge Infrastructure, and Wanfang Database, were searched independently by 2 reviewers until February 2016. Correlation coefficient (r or rs) values were obtained from each study, and 95% confidence intervals (CIs) were calculated using STATA12.0 software. A total of 2049 studies were produced, and 9 of which were analyzed (714 participants) in the meta-analysis. The pooled r observed medium relationship for all selected studies (r = 0.405, 95% CI 0.31-0.55), and notable heterogeneity was also tested between studies (χ = 17.72, P = .023; I = 54.9%). After the sensitivity and subgroup analysis, the heterogeneity significantly decreased. Subgroup analysis showed that MMSE score was stronger correlation between PaO2 and cognitive function than MoCA score in the COPD patients. Begg test did not indicate potential risk of publication bias. There was a negative correlation between cognitive function and anoxia in patients with COPD, so it may be extremely essential to predict and improve the status of hypoxia in COPD patients.

Effects of Atmospheric-Pressure N2, He, Air, and O2 Microplasmas on Mung Bean Seed Germination and Seedling Growth

NASA Astrophysics Data System (ADS)

Zhou, Renwu; Zhou, Rusen; Zhang, Xianhui; Zhuang, Jinxing; Yang, Size; Bazaka, Kateryna; (Ken) Ostrikov, Kostya

2016-09-01

Atmospheric-pressure N2, He, air, and O2 microplasma arrays have been used to investigate the effects of plasma treatment on seed germination and seedling growth of mung bean in aqueous solution. Seed germination and growth of mung bean were found to strongly depend on the feed gases used to generate plasma and plasma treatment time. Compared to the treatment with atmospheric-pressure O2, N2 and He microplasma arrays, treatment with air microplasma arrays was shown to be more efficient in improving both the seed germination rate and seedling growth, the effect attributed to solution acidification and interactions with plasma-generated reactive oxygen and nitrogen species. Acidic environment caused by air discharge in water may promote leathering of seed chaps, thus enhancing the germination rate of mung bean, and stimulating the growth of hypocotyl and radicle. The interactions between plasma-generated reactive species, such as hydrogen peroxide (H2O2) and nitrogen compounds, and seeds led to a significant acceleration of seed germination and an increase in seedling length of mung bean. Electrolyte leakage rate of mung bean seeds soaked in solution activated using air microplasma was the lowest, while the catalase activity of thus-treated mung bean seeds was the highest compared to other types of microplasma.

Effects of Atmospheric-Pressure N2, He, Air, and O2 Microplasmas on Mung Bean Seed Germination and Seedling Growth.

PubMed

Zhou, Renwu; Zhou, Rusen; Zhang, Xianhui; Zhuang, Jinxing; Yang, Size; Bazaka, Kateryna; Ken Ostrikov, Kostya

2016-09-01

Atmospheric-pressure N2, He, air, and O2 microplasma arrays have been used to investigate the effects of plasma treatment on seed germination and seedling growth of mung bean in aqueous solution. Seed germination and growth of mung bean were found to strongly depend on the feed gases used to generate plasma and plasma treatment time. Compared to the treatment with atmospheric-pressure O2, N2 and He microplasma arrays, treatment with air microplasma arrays was shown to be more efficient in improving both the seed germination rate and seedling growth, the effect attributed to solution acidification and interactions with plasma-generated reactive oxygen and nitrogen species. Acidic environment caused by air discharge in water may promote leathering of seed chaps, thus enhancing the germination rate of mung bean, and stimulating the growth of hypocotyl and radicle. The interactions between plasma-generated reactive species, such as hydrogen peroxide (H2O2) and nitrogen compounds, and seeds led to a significant acceleration of seed germination and an increase in seedling length of mung bean. Electrolyte leakage rate of mung bean seeds soaked in solution activated using air microplasma was the lowest, while the catalase activity of thus-treated mung bean seeds was the highest compared to other types of microplasma.

Analyzing the dependence of oxygen incorporation current density on overpotential and oxygen partial pressure in mixed conducting oxide electrodes.

PubMed

Guan, Zixuan; Chen, Di; Chueh, William C

2017-08-30

The oxygen incorporation reaction, which involves the transformation of an oxygen gas molecule to two lattice oxygen ions in a mixed ionic and electronic conducting solid, is a ubiquitous and fundamental reaction in solid-state electrochemistry. To understand the reaction pathway and to identify the rate-determining step, near-equilibrium measurements have been employed to quantify the exchange coefficients as a function of oxygen partial pressure and temperature. However, because the exchange coefficient contains contributions from both forward and reverse reaction rate constants and depends on both oxygen partial pressure and oxygen fugacity in the solid, unique and definitive mechanistic assessment has been challenging. In this work, we derive a current density equation as a function of both oxygen partial pressure and overpotential, and consider both near and far from equilibrium limits. Rather than considering specific reaction pathways, we generalize the multi-step oxygen incorporation reaction into the rate-determining step, preceding and following quasi-equilibrium steps, and consider the number of oxygen ions and electrons involved in each. By evaluating the dependence of current density on oxygen partial pressure and overpotential separately, one obtains the reaction orders for oxygen gas molecules and for solid-state species in the electrode. We simulated the oxygen incorporation current density-overpotential curves for praseodymium-doped ceria for various candidate rate-determining steps. This work highlights a promising method for studying the exchange kinetics far away from equilibrium.

Solute-solvent interactions in solutions of 2-hydroxy-5-chloro-3-nitroacetophenone isonicotinoylhydrazone in N, N-dimethylformamide at 298-313 K according to ultrasonic and viscometric data

NASA Astrophysics Data System (ADS)

Dikkar, A. B.; Pethe, G. B.; Aswar, A. S.

2015-12-01

Density (ρ), speed of sound ( u), and viscosity (η), measurements have been carried on 2-hydroxy- 5-chloro-3-nitroacetophenone isonicotinoylhydrazone (HCNAIH) in N, N-dimethylformamide at 298.15, 303.15, 308.15, and 313.15 K. Adiabatic compressibility (βs), intermolecular free length ( L f), acoustic impedance ( Z), internal pressure ( P int), the apparent molar volume ( V w), limiting apparent molar volume ( V w 0), partial molar expansibility (wE 0), apparent molar adiabatic compressibility ( K w), limiting apparent molar adiabatic compressibility ( K w 0), viscosity B coefficients of Jones-Dole equation have been calculated. The activation free energy (Δμ 2 0 *) for viscous flow in solution have been calculated from B coefficient and partial molar volume data. The calculated parameters are used to interpret the solute-solvent interactions and structure forming/breaking ability of solute in DMF.

[Correlation between end-tidal carbon dioxide and partial pressure of arterial carbon dioxide in ventilated newborns].

PubMed

Feng, Jin-Xing; Liu, Xiao-Hong; Huang, Hui-Jun; Yu, Zhen-Zhu; Yang, Hui; He, Liu-Fang

2014-05-01

To study the correlation between end-tidal carbon dioxide (PetCO2) and partial pressure of arterial carbon dioxide (PaCO2) in ventilated newborns. Thirty-one ventilated newborn underwent mainstream PetCO2 monitoring; meanwhile, arterial blood gas analysis was performed. The correlation and consistency between PetCO2 and PaCO2 were assessed. A total of 85 end-tidal and arterial CO2 pairs were obtained from 31 ventilated newborns. The mean PetCO2 (41±10 mm Hg) was significantly lower than the corresponding mean PaCO2 (46±11 mm Hg) (P<0.01). There was a significant positive correlation between PetCO2 and PaCO2 (r=0.92, P<0.01). The overall PetCO2 bias was 5.1±4.3 mm Hg (95% limits of consistency, -3.3 to 13.6 mmHg), and 5% (4/85) of the points were beyond the 95%CI. When the oxygenation index (OI) was less than 300 mm Hg (n=48), there was a significant positive correlation between PetCO2 and PaCO2 (r=0.85, P<0.01); the PetCO2 bias was 5.9±4.3 mm Hg (95% limits of consistency, -2.6 to 14.5 mm Hg), and 4.2% (2/48) of the points were beyond the 95%CI. When the OI was more than 300 mm Hg (n=37), there was also a significant positive correlation between PetCO2 and PaCO2 (r=0.91, P<0.01); the PetCO2 bias was 4.1±4.1 mm Hg (95% limits of consistency, -3.9 to 12.1 mm Hg), and 5% (2/37) of the points were beyond the 95%CI. There is a good correlation and consistency between PetCO2 and PaCO2 in ventilated newborns.

Effects of varying oxygen partial pressure on molten silicon-ceramic substrate interactions

NASA Technical Reports Server (NTRS)

Ownby, D. P.; Barsoum, M. W.

1980-01-01

The silicon sessile drop contact angle was measured on hot pressed silicon nitride, silicon nitride coated on hot pressed silicon nitride, silicon carbon coated on graphite, and on Sialon to determine the degree to which silicon wets these substances. The post-sessile drop experiment samples were sectioned and photomicrographs were taken of the silicon-substrate interface to observe the degree of surface dissolution and degradation. Of these materials, silicon did not form a true sessile drop on the SiC on graphite due to infiltration of the silicon through the SiC coating, nor on the Sialon due to the formation of a more-or-less rigid coating on the liquid silicon. The most wetting was obtained on the coated Si3N4 with a value of 42 deg. The oxygen concentrations in a silicon ribbon furnace and in a sessile drop furnace were measured using the protable thoria-yttria solid solution electrolyte oxygen sensor. Oxygen partial pressures of 10 to the minus 7 power atm and 10 to the minus 8 power atm were obtained at the two facilities. These measurements are believed to represent nonequilibrium conditions.

Fischer-Tropsch synthesis in near-critical n-hexane: Pressure-tuning effects

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

Bochniak, D.J.; Subramaniam, B.

For Fe-catalyzed Fischer-Tropsch (FT) synthesis with near-critical n-hexane (P{sub c} = 29.7 bar; T{sub c} = 233.7 C) as the reaction medium, isothermal pressure tuning from 1.2--2.4 P{sub c} (for n-hexane) at the reaction temperature (240 C) significantly changes syngas conversion and product selectivity. For fixed feed rates of syngas (H{sub 2}/CO = 0.5; 50 std. cm{sup 3}/g catalyst) and n-hexane (1 mL/min), syngas conversion attains a steady state at all pressures, increasing roughly threefold in this pressure range. Effective rate constants, estimated assuming a first-order dependence of syngas conversion on hydrogen, reveal that the catalyst effectiveness increases with pressuremore » implying the alleviation of pore-diffusion limitations. Pore accessibilities increase at higher pressures because the extraction of heavier hydrocarbons from the catalyst pores is enhanced by the liquid-like densities, yet better-than-liquid transport properties, of n-hexane. This explanation is consistent with the single {alpha} (= 0.78) Anderson-Schulz-Flory product distribution, the constant chain termination probability, and the higher primary product (1-olefin) selectivities ({approximately}80%) observed at the higher pressures. Results indicate that the pressure tunability of the density and transport properties of near-critical reaction media offers a powerful tool to optimize catalyst activity and product selectivity during FT reactions on supported catalysts.« less

Chemical stabilization and high pressure synthesis of Ba-free Hg-based superconductors, (Hg,M)Sr2Ca(n-1)Cu(n)O(y)(n=1 to approximately 3)

NASA Technical Reports Server (NTRS)

Kishio, K.; Shimoyama, J.; Hahakura, S.; Kitazawa, K.; Yamaura, K.; Hiroi, Z.; Takano, M.

1995-01-01

A homologous series of new Hg-based HTSC compounds, (Hg,M)Sr2Ca(n - 1)Cu(n)P(y) with n = 1 to 3, have been synthesized. The stabilization of the pure phases have been accomplished by chemical doping of third elements such as M = Cr, Mo and Re. While the Hgl2O1(n = 1) phase was readily obtained in this way, it was necessary to simultaneously dope Y into the Ca site to stabilize the Hg1212(n = 2) phase. On the other hand, single-phase Y-free Hg1212(n = 2) and Hg1223 (n = 3) samples were synthesized only under a high pressure of 6 GPa. In sharp contrast to the Ba containing compounds, all the samples prepared in the present study have been quite stable during the synthesis and no deterioration in air has been observed after the preparation.

A Theoretical Study of Methanol Oxidation on RuO 2(110): Bridging the Pressure Gap

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

Latimer, Allegra A.; Abild-Pedersen, Frank; Norskov, Jens K.

Partial oxidation catalysis is often fraught with selectivity problems, largely because there is a tendency of oxidation products to be more reactive than the starting material. One industrial process that has successfully overcome this problem is partial oxidation of methanol to formaldehyde. This process has become a global success, with an annual production of 30 million tons. Although ruthenium catalysts have not shown activity as high as the current molybdena or silver-based industrial standards, the study of ruthenium systems has the potential to elucidate which catalyst properties facilitate the desired partial oxidation reaction as opposed to deep combustion due tomore » a pressure-dependent selectivity “switch” that has been observed in ruthenium-based catalysts. In this work, we find that we are able to successfully rationalize this “pressure gap” using near-ab initio steady-state microkinetic modeling on RuO 2(110). We obtain molecular desorption prefactors from experiment and determine all other energetics using density functional theory. We show that, under ambient pressure conditions, formaldehyde production is favored on RuO 2(110), whereas under ultrahigh vacuum pressure conditions, full combustion to CO 2 takes place. We glean from our model several insights regarding how coverage effects, oxygen activity, and rate-determining steps influence selectivity and activity. As a result, we believe the understanding gained in this work might advise and inspire the greater partial oxidation community and be applied to other catalytic processes which have not yet found industrial success.« less

A Theoretical Study of Methanol Oxidation on RuO 2(110): Bridging the Pressure Gap

DOE PAGES

Latimer, Allegra A.; Abild-Pedersen, Frank; Norskov, Jens K.

2017-05-26

Partial oxidation catalysis is often fraught with selectivity problems, largely because there is a tendency of oxidation products to be more reactive than the starting material. One industrial process that has successfully overcome this problem is partial oxidation of methanol to formaldehyde. This process has become a global success, with an annual production of 30 million tons. Although ruthenium catalysts have not shown activity as high as the current molybdena or silver-based industrial standards, the study of ruthenium systems has the potential to elucidate which catalyst properties facilitate the desired partial oxidation reaction as opposed to deep combustion due tomore » a pressure-dependent selectivity “switch” that has been observed in ruthenium-based catalysts. In this work, we find that we are able to successfully rationalize this “pressure gap” using near-ab initio steady-state microkinetic modeling on RuO 2(110). We obtain molecular desorption prefactors from experiment and determine all other energetics using density functional theory. We show that, under ambient pressure conditions, formaldehyde production is favored on RuO 2(110), whereas under ultrahigh vacuum pressure conditions, full combustion to CO 2 takes place. We glean from our model several insights regarding how coverage effects, oxygen activity, and rate-determining steps influence selectivity and activity. As a result, we believe the understanding gained in this work might advise and inspire the greater partial oxidation community and be applied to other catalytic processes which have not yet found industrial success.« less

Small, high-pressure, liquid oxygen turbopump

NASA Technical Reports Server (NTRS)

Csomor, A.

1978-01-01

A small, high-pressure, LOX turbopump was designed, fabricated, and tested. The pump was of a single-stage, centrifugal type; power to the pump was supplied by a single-stage, partial-admission, axial-impulse turbine. Design conditions included an operating speed of 7330 rad/sec (70,000 rpm) pump discharge pressure of 2977 N/sq cm (4318 psia), and a pump flowrate of 16.4 kg/s (36.21 lb/sec). The turbine was propelled by LOX/LH2 combustion products at 1041 K (1874 R) inlet temperature, and at a design pressure ratio of 1.424. Test data obtained with the turbopump are presented and mechanical performance is discussed.

The Effect of O2, H2O, and N2 on the Fatigue Crack Growth Behavior of an Alpha + Beta Titanium Alloy at 24 C and 177 C

NASA Technical Reports Server (NTRS)

Smith, Stephen W.; Piascik, Robert S.

2001-01-01

To study the effects of atmospheric species on the fatigue crack growth behavior of an a+B titanium alloy (Ti 6-2-2-2-2) at room temperature and 177 C, fatigue tests were performed in laboratory air, ultrahigh vacuum, and high purity water vapor, oxygen, nitrogen and helium at various partial pressures. Accelerated fatigue crack growth rates in laboratory air compared to ultrahigh vacuum are linked to the damaging effects of both water vapor and oxygen. Observations of the fatigue crack growth behavior in ultrahigh purity environments, along with surface film analysis using X-ray photoelectron spectroscopy (XPS), suggest that multiple crack-tip processes govern the damaging effects of air. Three possible mechanisms are proposed: 1) at low pressure (less than 10(exp -1) Pa), accelerated da/dN is likely due to monolayer adsorption on crack-tip surfaces presumably resulting in decreased bond strengths at the fatigue crack tip, 2) for pressures greater than 10(exp -1) Pa, accelerated da/dN in oxygen may result from oxidation at the crack tip limiting reversible slip, and 3) in water vapor, absorption of atomic hydrogen at the reactive crack tip resulting in process zone embrittlement.

Partial Discharge Characteristics in Composite Insulation Systems with PPLP for HTS Cable

NASA Astrophysics Data System (ADS)

Kikuchi, Y.; Yamashita, K.; Kumada, A.; Hidaka, K.; Tatamidani, K.; Masuda, T.

2014-05-01

The electrical insulation system of high-temperature superconducting (HTS) cable consists of liquid nitrogen (N2(l)) and polypropylene laminated paper (PPLP). Partial discharge (PD) may occur in butt gaps of the insulation layers and its characteristics imply the insulation performance of HTS cables. N2(l) cooling system is installed in the power system and N2(l) will flow through the cables during the system operation. Filling the HTS cable with N2(l) in order to perform pre-shipment inspection is time-consuming and costly for cable manufacturers. Therefore, they are trying to find a cost effective method for pre-shipment inspections. One alternative is to use high pressure gaseous nitrogen (N2(g)) instead of N2(l). This article investigates PD characteristics such as PD inception electric field (PDIE) and PD extinction electric field (PDEE) in butt gaps of HTS cables in 0.1 to 0.3 MPa and 0.1 MPa to 1.0 MPa N2(g) environments. For assessing the surface/volume effects, PD characteristics are measured with changing the size of butt gaps. It turns out that PDIE and PDEE in N2(g) are linearly correlated with those in N2(l) at any gas pressure in our testing, and PDIE in 1.0 MPa N2(g) is almost 30% of that in 0.2 MPa It suggests that PD characteristics in N2(l) can be extrapolated from those in N2(g).

High nitrogen pressure solution growth of GaN

NASA Astrophysics Data System (ADS)

Bockowski, Michal

2014-10-01

Results of GaN growth from gallium solution under high nitrogen pressure are presented. Basic of the high nitrogen pressure solution (HNPS) growth method is described. A new approach of seeded growth, multi-feed seed (MFS) configuration, is demonstrated. The use of two kinds of seeds: free-standing hydride vapor phase epitaxy GaN (HVPE-GaN) obtained from metal organic chemical vapor deposition (MOCVD)-GaN/sapphire templates and free-standing HVPE-GaN obtained from the ammonothermally grown GaN crystals, is shown. Depending on the seeds’ structural quality, the differences in the structural properties of pressure grown material are demonstrated and analyzed. The role and influence of impurities, like oxygen and magnesium, on GaN crystals grown from gallium solution in the MFS configuration is presented. The properties of differently doped GaN crystals are discussed. An application of the pressure grown GaN crystals as substrates for electronic and optoelectronic devices is reported.

Combined Hyperbaric Oxygen Partial Pressure at 1.4 Bar with Infrared Radiation: A Useful Tool To Improve Tissue Hypoxemia?

PubMed

Dünnwald, Tobias; Held, Julia; Balan, Petru; Pecher, Otto; Zeiger, Thomas; Hartig, Frank; Mur, Erich; Weiss, Günter; Schobersberger, Wolfgang

2018-06-13

Tissue hypoxia contributes to the pathogenesis of several acute and chronic diseases. Hyperbaric oxygen therapy (HBO) and whole-body warming using low-temperature infrared technology (LIT) are techniques that might improve hypoxemia. Combining HBO and LIT as hyperbaric oxygen therapy combined with low-temperature infrared radiation (HBOIR) might be an approach that results in positive synergistic effects on oxygenation. LIT increases blood flow and could reduce HBO-induced vasoconstriction, and hyperoxia could compensate for the increased metabolic oxygen requirements mediated by LIT. Both LIT and HBO increase the oxygen diffusion distance in the tissues. HBOIR at 0.5 bar has been shown to be safe and feasible. However, physiological responses and the safety of HBOIR at an increased oxygen (O2) partial pressure of 1.4 bar or 2.4 atmospheres absolute (ATA) still need to be determined. The hope is that should HBOIR at an increased oxygen partial pressure of 1.4 bar be safe, future studies to examine its efficacy in patients with clinical conditions, which include peripheral arterial disease (PAD) or wound healing disorders, will follow. The results of pilot studies have shown that HBOIR at an overload pressure is safe and well tolerated in healthy participants but can generate moderate cardiovascular changes and an increase in body temperature. From the findings of this pilot study, due to its potential synergistic effects, HBOIR could be a promising tool for the treatment of human diseases associated with hypoxemia.

The influence of a hyperbaric environment and increased oxygen partial pressure on the corrosion of dental alloys.

PubMed

Mehl, Christian; Heblich, Frank; Lenz, Rudolf; Ludwig, Klaus; Kern, Matthias

2011-09-01

The purpose of this in-vitro study was to determine whether there is a correlation between a hyperbaric environment or increased oxygen partial pressure and the corrosion of dental alloys used for dental restorations in divers. Samples of three commercially available dental alloys (palladium-based, reduced-gold-content and high-gold-content) were tested in the DIN EN ISO 1562 static immersion test and the amount of dissolved ions measured by atomic absorption spectrometry. The specimens were exposed to one of the following three conditions: normobaric and normoxic conditions (PO2 21 kPa); 608 kPa (6 bar, PO2 127 kPa) pressurised air in a pressure chamber or 506 kPa (5 bar, PO2 304 kPa) pressurised nitrox in a pressure chamber. None of the exposures suggested a correlation between increased ion solubility as a measure of corrosion and increased ambient pressure of the three alloys. The reduced-gold-content alloy released zinc ions at twice the weekly recommended dose. When the palladium-based alloy was exposed to a hyperbaric or hyperbaric/hyperoxic environment, ion solubility increased only slightly for gallium and silver. Within the limited sample size of the current study it can be concluded that hyperbaric and/or hyperoxic conditions do not seem to be a risk for increased corrosion for any of the three tested alloys.

Monitoring in microvascular tissue transfer by measurement of oxygen partial pressure: four years experience with 125 microsurgical transplants.

PubMed

Jonas, René; Schaal, Thomas; Krimmel, Michael; Gülicher, Dirk; Reinert, Siegmar; Hoffmann, Jürgen

2013-06-01

In a prospective study, the characteristics and benefit of an invasive measurement of oxygen partial pressure (pO(2)) with the aid of a polarographic sensor were investigated in 125 microsurgical reconstructions of the head and neck area over a period of 45 months. Measurements were performed over 96 h in eight different types of microsurgically revascularized flaps for extra- and intraoral reconstructions and were evaluated separately for each flap type. Of 125 reconstructions the system indicated malperfusion in 18 cases. Salvage surgery was performed in 17 cases due to venous thrombosis (6 cases), arterial thrombosis (3 cases), a combination of arterial and venous thrombosis (2 cases), rheological problems (3 cases), venous insufficiency by hematoma (2 cases) and kinking of vessels (1 case). In 10 cases salvage surgery was successful, 7 flaps were lost despite salvage surgery. In all these cases, the polarographic probe indicated the necessity of salvage surgery correctly. After 96 h no malperfusion was seen. Postoperatively, a common and characteristic development of the oxygen partial pressure in different types of flaps was seen. Initially, a clear increase of pO(2) could be measured. During 96 h, a slow decrease of pO(2) was observed. In conclusion polarographic measurement of pO(2) can be an excellent apparative supplement for the postoperative clinical control of microsurgically revascularized transplants. In buried flaps, this technique represents the only reliable method for transplant monitoring. Copyright © 2012 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Vapor Pressure of Methyl Salicylate and n-Hexadecane

DTIC Science & Technology

2014-01-01

VAPOR PRESSURE OF METHYL SALICYLATE AND N-HEXADECANE ECBC-TR-1184 David E. Tevault Leonard C. Buettner...REPORT TYPE Final 3. DATES COVERED (From - To) Mar 2000-Dec 2001 4. TITLE AND SUBTITLE Vapor Pressure of Methyl Salicylate and n-Hexadecane 5a...ABSTRACT Vapor pressure data are reported for O-hydroxybenzoic acid, methyl ester, more commonly known as methyl salicylate (MeS), and n-hexadecane in

Alteration of striatal dopamine levels under various partial pressure of oxygen in pre-convulsive and convulsive phases in freely-moving rats.

PubMed

Lavoute, Cécile; Weiss, Michel; Risso, Jean-Jacques; Rostain, Jean-Claude

2014-02-01

The purpose of this study was to investigate the change in the striatal dopamine (DA) level in freely-moving rat exposed to different partial pressure of oxygen (from 1 to 5 ATA). Some works have suggested that DA release by the substantia nigra pars compacta (SNc) neurons in the striatum could be disturbed by hyperbaric oxygen (HBO) exposure, altering therefore the basal ganglia activity. Such changes could result in a change in glutamatergic and GABAergic control of the dopaminergic neurons into the SNc. Such alterations could provide more information about the oxygen-induced seizures observed at 5 ATA in rat. DA-sensitive electrodes were implanted into the striatum under general anesthesia. After 1 week rest, awaked rats were exposed to oxygen-nitrogen mixture at a partial pressure of oxygen of 1, 2, 3, 4 and 5 ATA. DA level was monitored continuously (every 3 min) by in vivo voltammetry before and during HBO exposure. HBO induced a decrease in DA level in relationship to the increase in partial pressure of oxygen from 1 ATA to 4 ATA (-15 % at 1 ATA, -30 % at 2 ATA, -40 % at 3 ATA, -45 % at 4 ATA), without signs of oxygen toxicity. At 5 ATA, DA level strongly decreases (-75 %) before seizure which occurred after 27 min ± 7 HBO exposure. After the epileptic seizure the decrease in DA level disappeared. These changes and the biphasic effect of HBO were discussed in function of HBO action on neurochemical regulations of the nigro striatal pathway.

Whole-plant growth and N utilization in transgenic rice plants with increased or decreased Rubisco content under different CO2 partial pressures.

PubMed

Sudo, Emi; Suzuki, Yuji; Makino, Amane

2014-11-01

Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) strongly limits photosynthesis at lower CO2 concentration [CO2] whereas [corrected] Rubisco limitation is cancelled by elevated [CO2]. Therefore, increase or reduction in Rubisco content by transformation with a sense or an antisense RBCS construct are expected to alter the biomass production under different CO2 levels. RBCS-sense (125% Rubisco of wild-type) and -antisense (35% Rubisco of wild-type) rice (Oryza sativa L.) plants were grown for 63 days at three different CO2 levels: low [CO2] (28 Pa), normal [CO2] (40 Pa) and elevated [CO2] (120 Pa). The biomass of RBCS-sense plants was 32% and 15% greater at low [CO2] and normal [CO2] than that of the wild-type plants, respectively, but did not differ at elevated [CO2]. Conversely, the biomass of RBCS-antisense plants was the smallest at low [CO2]. Thus, overproduction of Rubisco was effective for biomass production at low [CO2]. Greater biomass production at low [CO2] in RBCS-sense plants was caused by an increase in the net assimilation rate, and associated with an increase in the amount of N uptake. Furthermore, Rubisco overproduction in RBCS-sense plants was also promoted at low [CO2]. Although it seems that low [CO2]-growth additionally stimulates the effect of RBCS overexpression, such a phenomenon observed at low [CO2] was mediated through an increase in total leaf N content. Thus, the dependence of the growth improvement in RBCS-sense rice on growth [CO2] was closely related to the degree of Rubisco overproduction which was accompanied not only by leaf N content but also by whole plant N content. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Detecting Random, Partially Random, and Nonrandom Minnesota Multiphasic Personality Inventory-2 Protocols

ERIC Educational Resources Information Center

Pinsoneault, Terry B.

2007-01-01

The ability of the Minnesota Multiphasic Personality Inventory-2 (MMPI-2; J. N. Butcher et al., 2001) validity scales to detect random, partially random, and nonrandom MMPI-2 protocols was investigated. Investigations included the Variable Response Inconsistency scale (VRIN), F, several potentially useful new F and VRIN subscales, and F-sub(b) - F…

Effect of oxygen partial pressure on superconducting properties of Bi-2212/Ag tapes prepared by doctor-blade method

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

Inoue, N.; Okada, M.; Higashiyama, K.

1997-06-01

The authors have investigated the relationship between oxygen partial pressure (P{sub O{sub 2}}) during the partial-melting process and superconducting properties for doctor-blade processed Bi-2212/Ag tapes. Tapes were heat-treated at various P{sub O{sub 2}} value of 0.01-1.00 atm. The DTA results for the doctor-blade tapes showed the melting point of the oxide rose with increasing P{sub O{sub 2}}. Correspondingly, the optimum heat-treatment temperature also increased with increasing P{sub O{sub 2}}. The tapes at P{sub O{sub 2}}=1.00 atm had the highest J{sub c} values of over 10{sup 5} A/cm{sup 2} at conditions of 4.2K, 10T, and their a.c. susceptibility showed a sharpmore » transition indicating improved intergrain coupling. Examination of cross sections for tapes melted above 0.20atm PO{sub 2} showed the good crystal alignment. From these results, it was concluded that processing at high PO{sub 2} was an effective method to obtain good superconducting properties for doctor-blade tapes.« less

Small, high-pressure liquid oxygen turbopump

NASA Technical Reports Server (NTRS)

Csomor, A.; Sutton, R.

1977-01-01

A small, high-pressure, liquid oxygen turbopump was designed, fabricated, and tested. The pump was of a single-stage, centrifugal type; power to the pump was supplied by a single-stage, partial emission, axial-impulse turbine. Design conditions included an operating speed of 70,000 rpm, pump discharge pressure of 2977 N/sq cm (4318 psia), and a pump flowrate of 16.4 kg/s (36.21 lb/sec). The turbine was propelled by LO2/LH2 combustion products at 1041 K (1874 R) inlet temperature, and at a design pressure ratio of 1.424. The approaches used in the detail analysis and design of the turbopump are described, and fabrication methods are discussed. Data obtained from gas generator tests, turbine performance calibration, and turbopump testing are presented.

Effects of changing body position on oxygenation and arterial blood pressures in foals anesthetized with guaifenesin, ketamine, and xylazine.

PubMed

Braun, Christina; Trim, Cynthia M; Eggleston, Randy B

2009-01-01

To investigate the impact of a change in body position on blood gases and arterial blood pressures in foals anesthetized with guaifenesin, ketamine, and xylazine. Prospective, randomized experimental study. Twelve Quarter Horse foals, age of 5.4 +/-0.9 months and weighing 222 +/- 48 kg. Foals were anesthetized with guaifenesin, ketamine, and xylazine for 40 minutes in lateral recumbency and then assigned to a change in lateral recumbency after hoisting (Group 1, n = 6), or no change (Group 2, n = 6). Oxygen 15 L minute(-1) was insufflated into the endotracheal tube throughout anesthesia. Arterial blood pressure, heart rate, respiratory rate (f(R)), inspired fraction of oxygen (FIO(2)), and end-tidal carbon dioxide (PE'CO(2)) were measured every 5 minutes. Arterial pH and blood gases [arterial partial pressure of oxygen (PaO(2)), arterial partial pressure of carbon dioxide (PaCO(2))] were measured at 10, 30, and 40 minutes after induction, and 5 minutes after hoisting. Alveolar dead space ventilation and PaO(2)/FIO(2) were calculated. Two repeated measures models were used. All hypothesis tests were two-sided and significance level was alpha = 0.05. All values are presented as least square means +/- SE. Values at time-matched points from the two groups were not significantly different so they were combined. Arterial partial pressure of oxygen decreased significantly from 149 +/- 14.4 mmHg before hoisting to 92 +/- 11.6 mmHg after hoisting (p = 0.0013). The PaO(2)/FIO(2) ratio decreased from 275 +/- 30 to 175 +/- 24 (p = 0.0055). End-tidal carbon dioxide decreased significantly from 48.7 +/- 1.6 to 44.5 +/- 1.2 mmHg (p = 0.021). Arterial partial pressure of carbon dioxide, blood pressures and heart rates measured 5 minutes after hoisting were not different from measurements obtained before hoisting. Hoisting decreased PaO(2) in anesthetized healthy foals. Administration of supplemental oxygen is recommended to counter the decrease in oxygenation and PaO(2

CO(2) partial pressure and calcite saturation in springs - useful data for identifying infiltration areas in mountainous environments.

PubMed

Hilberg, Sylke; Brandstätter, Jennifer; Glück, Daniel

2013-04-01

Mountainous regions such as the Central European Alps host considerable karstified or fractured groundwater bodies, which meet many of the demands concerning drinking water supply, hydropower or agriculture. Alpine hydrogeologists are required to describe the dynamics in fractured aquifers in order to assess potential impacts of human activities on water budget and quality. Delineation of catchment areas by means of stable isotopes and hydrochemical data is a well established method in alpine hydrogeology. To achieve reliable results, time series of (at least) one year and spatial and temporal close-meshed data are necessary. In reality, test sites in mountainous regions are often inaccessible due to the danger of avalanches in winter. The aim of our work was to assess a method based on the processes within the carbonic acid system to delineate infiltration areas by means of single datasets consisting of the main hydrochemical parameters of each spring. In three geologically different mountainous environments we managed to classify the investigated springs into four groups. (1) High PCO2 combined with slight super-saturation in calcite, indicating relatively low infiltration areas. (2) Low PCO2 near atmospheric conditions in combination with calcite saturation, which is indicative of relatively high infiltration areas and a fractured aquifer which is not covered by topsoil layers. (3) High PCO2 in combination with sub-saturation in calcite, representing a shallow aquifer with a significant influence of the topsoil layer. (4) The fourth group of waters is characterized by low PCO2 and sub-saturation in calcite, which is interpreted as evidence for a shallow aquifer without significant influence of any hard rock aquifer or topsoil layer. This study shows that CO2-partial pressure can be an ideal natural tracer to estimate the elevation of infiltration areas, especially in non-karstified fractured groundwater bodies.

Pressure-induced Structural Transformations in LanthanideTitanates: La2TiO5 and Nd2TiO5

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

F Zhang; J Wang; M Lang

The structure of orthorhombic rare earth titanates of La{sub 2}TiO{sub 5} and Nd{sub 2}TiO{sub 5}, where Ti cations are in five-fold coordination with oxygen, has been studied at high pressures by X-ray diffraction (XRD), Raman scattering measurements, and quantum mechanical calculations. Both XRD and Raman results indicated two pressure-induced phase transitions during the process. An orthorhombic super cell (a x b x 2c) formed at a pressure between 6 and 10 GPa, and then transformed to a hexagonal high-pressure phase accompanied by partial decomposition. The hexagonal high-pressure phase is quenchable. Detailed structural analysis indicated that the five-coordinated TiO{sub 5} polyhedramore » remain during the formation of super cell, but the orthorhombic-to-hexagonal phase transition at high pressures is a reconstructive process, and the five-fold Ti-O coordination increased to more than 6. This phase transition sequence was verified by quantum mechanical calculations.« less

Influence of Oxygen Partial Pressure during Processing on the Thermoelectric Properties of Aerosol-Deposited CuFeO₂.

PubMed

Stöcker, Thomas; Exner, Jörg; Schubert, Michael; Streibl, Maximilian; Moos, Ralf

2016-03-24

In the field of thermoelectric energy conversion, oxide materials show promising potential due to their good stability in oxidizing environments. Hence, the influence of oxygen partial pressure during synthesis on the thermoelectric properties of Cu-Delafossites at high temperatures was investigated in this study. For these purposes, CuFeO₂ powders were synthetized using a conventional mixed-oxide technique. X-ray diffraction (XRD) studies were conducted to determine the crystal structures of the delafossites associated with the oxygen content during the synthesis. Out of these powders, films with a thickness of about 25 µm were prepared by the relatively new aerosol-deposition (AD) coating technique. It is based on a room temperature impact consolidation process (RTIC) to deposit dense solid films of ceramic materials on various substrates without using a high-temperature step during the coating process. On these dense CuFeO₂ films deposited on alumina substrates with electrode structures, the Seebeck coefficient and the electrical conductivity were measured as a function of temperature and oxygen partial pressure. We compared the thermoelectric properties of both standard processed and aerosol deposited CuFeO₂ up to 900 °C and investigated the influence of oxygen partial pressure on the electrical conductivity, on the Seebeck coefficient and on the high temperature stability of CuFeO₂. These studies may not only help to improve the thermoelectric material in the high-temperature case, but may also serve as an initial basis to establish a defect chemical model.

Pressure-induced stable BeN4 as a high-energy density material

NASA Astrophysics Data System (ADS)

Zhang, Shoutao; Zhao, Ziyuan; Liu, Lulu; Yang, Guochun

2017-10-01

Polynitrogens are the ideal rocket fuels or propellants. Due to strong triple N≡N bond in N2, the direct polymerization of nitrogen is rather difficult (i.e. extreme high temperature and high pressure). However, the use of nitrides as precursors or the reaction of N2 with other elements has been proved to be an effective way to obtain polynitrogens. Here, with assistance of the advanced first-principles swarm-intelligence structure searches, we found that P 1 bar -BeN4, containing infinite zigzag-like polymeric nitrogen chains, can be synthesized by compressing the mixture of Be3N2 and N2 at 25.4 GPa, which is greatly lower than 110 GPa for synthesizing cubic gauche nitrogen and other polynitrogen compounds (e.g. bulk CNO at 52 GPa and SN4 at 49 GPa). Its structural stability can be attributed to the coexistence of ionic Be-N and covalent N-N bonds. Intriguingly, this phase has high kinetic stability and remains metastable at ambient pressure. The exceptional properties, including high energy density (3.60 kJ g-1), high nitrogen content (86.1%), high dynamical stability, and low polymerization pressure, make P 1 bar -structured BeN4 a promising high energy material. Infinite nitrogen chains in P 1 bar -BeN4 transform to N10 rings network in P21/c phase at 115.1 GPa. P 1 bar -BeN4 is metallic, while P21/c-BeN4 is an insulator.

Regimes of an atmospheric pressure nanosecond repetitively pulsed discharge for methane partial oxidation

NASA Astrophysics Data System (ADS)

Maqueo, P. D. G.; Maier, M.; Evans, M. D. G.; Coulombe, S.; Bergthorson, J. M.

2018-04-01

The operation of a nanosecond repetitively pulsed discharge for partial oxidation of CH4 is characterized at atmospheric pressure and room temperature. Two regimes are observed: diffuse and filamentary. The first is a low power regime, characterized by low rotational temperatures around 400 K. The second is much more energetic with rotational temperatures close to 600 K. Both have vibrational temperatures of at least 10 times their rotational temperatures. The average electron number density was determined to be 8.9×1015 and 4.0×1017 cm-3, respectively, showing an increase in the ionization fraction in the more powerful filamentary regime. Results of CH4 conversion to H2, CO, CO2 and C2H6 are presented for the filamentary regime, while the diffuse regime shows no measurable conversion ability. As expected, oxidative mixtures show higher conversion ability than pure CH4. A maximum conversion efficiency of 26.3% and a maximum energy efficiency of 19.7% were reached for the oxidative mixtures.

Tissue oxygen partial pressure in the tibialis anterior muscle in patients with claudication before, during and after a two-stage treadmill stress test.

PubMed

Jung, F; Krüger, A; Pindur, G; Sternitzky, R; Franke, R P; Gori, T

2014-01-01

The role of the microcirculation in the pathophysiology and symptoms of peripheral arterial obliterative disease (PAOD) has been progressively emphasized during the past decades. Under resting conditions, already, the tissue oxygen partial pressure in the m. tibialis anterior (pO2im) is reduced to about 50% compared to healthy subjects. In the framework of this study the pO2im of patients with PAOD stage II according to Fontaine (n=16) in the m. tibialis anterior was measured under resting conditions and during walking on a treadmill in comparison to healthy subjects (n=10). Under resting conditions the pO2im only marginally differed between PAOD patients and healthy subjects. But during exercise the pO2im dropped significantly more severely in PAOD patients and a return to baseline values could only be reached when the treadmill was stopped and the patients stood still. The pO2im minima correlated clearly with the clinical symptom of calf pain. The data revealed that the pO2im values were lower in PAOD patients and dropped significantly faster during walking compared to the pO2im values in healthy subjects. The pO2im decrease correlated with the calf pain occurring when the pO2im values approached or fell below 10 mmHg.

[The influence of low partial oxygen pressure on the biolodical process of mesenchymal stromal cells].

PubMed

Berezovskyĭ, V Ia; Plotnikova, L M; Vesel'skyĭ, S P; Litovka, I H

2014-01-01

The influence of low partial oxygen pressure (Po2) on the amino acid composition in culture medium of human mesenchymal stromal cell (MSC) lines 4BL has been studied. At 23 mm Hg (3% oxygen), a significant decrease (by 31%) in the concentration of proline and hydroxyproline was registered. Under these conditions, the concentration of serine and aspartic acid decreased by 45% compared to the control. Maximum consumption of free amino acids from the culture medium required for the synthesis of collagen (proline and hydroxyproline by 42%, serine and aspartic acid by 62%) was observed at a gas-phase Po2 of 38 mm Hg (5% O2). At Po2 76 mm Hg (10% O2), a lack of amino acids proline and hydroxyproline was only 21%, while that of glutamine and alanine amounted 12% compared to the control. This intensity ratio of consumption of amino acids may indicate that the maximum of MSC vital functions occurs at Po2 38 mm Hg.

Changes in the partial pressure of carbon dioxide in the Mauritanian-Cap Vert upwelling region between 2005 and 2012

NASA Astrophysics Data System (ADS)

González-Dávila, Melchor; Magdalena Santana Casiano, J.; Machín, Francisco

2017-08-01

Coastal upwellings along the eastern margins of major ocean basins represent regions of large ecological and economic importance due to the high biological productivity. The role of these regions for the global carbon cycle makes them essential in addressing climate change. The physical forcing of upwelling processes that favor production in these areas are already being affected by global warming, which will modify the intensity of upwelling and, consequently, the carbon dioxide cycle. Here, we present monthly high-resolution surface experimental data for temperature and partial pressure of carbon dioxide in one of the four most important upwelling regions of the planet, the Mauritanian-Cap Vert upwelling region, from 2005 to 2012. This data set provides direct evidence of seasonal and interannual changes in the physical and biochemical processes. Specifically, we show an upwelling intensification and an increase of 0.6 Tg yr-1 in CO2 outgassing due to increased wind speed, despite increased primary productivity. This increase in CO2 outgassing together with the observed decrease in sea surface temperature at the location of the Mauritanian Cap Blanc, 21° N, produced a pH rate decrease of -0.003 ± 0.001 yr-1.

Elastic behaviour and high-pressure phase transition of the P21/n LiAlGe2O6pyroxene

NASA Astrophysics Data System (ADS)

Artac, Andreas; Miletich-Pawliczek, Ronald; Nestola, Fabrizio; Redhammer, Günther J.; Secco, Luciano

2014-05-01

In a recent work by Redhammer et al. (2012), investigating a synthetic pyroxene sample with composition LiAlGe2O6, a new space group for the big family of pyroxenes has been surprisingly discovered renewing the interest for Li-bearing pyroxene compounds. Actually, the authors of that work intended to investigate the effect of the Si-Ge substitution on the high-pressure behaviour and possibly on the phase transition with respect to spodumene, LiAlSi2O6, investigated by Arlt and Angel in 2000. Spodumene in fact, not only shows a strong first order phase transition at 3.19 GPa from C2/c to P21/c but the low symmetry C2/c shows the greatest bulk modulus never found in pyroxenes (i.e. 144.2 GPa with the first pressure derivative fixed to 4). Redhammer et al. (2012) discovered that substituting Si for Ge in the spodumene structure the effect is dramatic in terms of symmetry change at room conditions with the Ge-spodumene showing a P21/n space group, first discovery of such symmetry in the big family of pyroxene. In this work we loaded one crystal of LiAlGe2O6 in a diamond-anvil cell and investigated the elastic behaviour and its possible high-pressure phase transition by single-crystal X-ray diffraction. In detail, we measured the unit-cell parameters using a Huber four-circle diffractometer equipped with a point detector up to about 9 GPa. The crystal structure was measured at different pressures loading simultaneously two fragments of the same crystal with a different orientation in the same diamond-anvil cell in order to cover a wider portion of the reciprocal space. The intensity data were measured on a STADI IV four-circle diffractometer equipped with a CCD using a diamond-backing plate cell, which gives better structural results with respect to a beryllium backing plate one (i.e. Periotto et al. 2011). The first important result of our work is that we found at about 5.2 GPa a very strong first-order phase transformation from P21/n to P21/c and this is the first

Partial neuroprotection by nNOS inhibition during profound asphyxia in preterm fetal sheep

PubMed Central

Drury, Paul P.; Davidson, Joanne O.; van den Heuij, Lotte G.; Tan, Sidhartha; Silverman, Richard B.; Ji, Haitao; Blood, Arlin B.; Fraser, Mhoyra; Bennet, Laura; Jan Gunn, Alistair

2013-01-01

Preterm brain injury is partly associated with hypoxia-ischemia starting before birth. Excessive nitric oxide production during HI may cause nitrosative stress, leading to cell membrane and mitochondrial damage. We therefore tested the hypothesis that therapy with a new, selective neuronal nitric oxide synthase (nNOS) inhibitor, JI-10 (0.022 mg/kg bolus, n=8), given 30 min before 25 min of complete umbilical cord occlusion was protective in preterm fetal sheep at 101-104 d gestation (term is 147 d), compared to saline (n=8). JI-10 had no effect on fetal blood pressure, heart rate, carotid and femoral blood flow, total EEG power, nuchal activity, temperature or intracerebral oxygenation on near-infrared spectroscopy during or after occlusion. JI-10 was associated with later onset of post-asphyxial seizures compared with saline (p<0.05), and attenuation of the subsequent progressive loss of cytochrome oxidase (p<0.05). After 7 days recovery, JI-10 was associated with improved neuronal survival in the caudate nucleus (p<0.05), but not the putamen or hippocampus, and more CNPase positive oligodendrocytes in the periventricular white matter (p<0.05). In conclusion, prophylactic nNOS inhibition before profound asphyxia was associated with delayed onset of seizures, slower decline of cytochrome oxidase and partial white and grey matter protection, consistent with protection of mitochondrial function. PMID:24120436

Partial neuroprotection by nNOS inhibition during profound asphyxia in preterm fetal sheep.

PubMed

Drury, Paul P; Davidson, Joanne O; van den Heuij, Lotte G; Tan, Sidhartha; Silverman, Richard B; Ji, Haitao; Blood, Arlin B; Fraser, Mhoyra; Bennet, Laura; Gunn, Alistair Jan

2013-12-01

Preterm brain injury is partly associated with hypoxia-ischemia starting before birth. Excessive nitric oxide production during HI may cause nitrosative stress, leading to cell membrane and mitochondrial damage. We therefore tested the hypothesis that therapy with a new, selective neuronal nitric oxide synthase (nNOS) inhibitor, JI-10 (0.022mg/kg bolus, n=8), given 30min before 25min of complete umbilical cord occlusion was protective in preterm fetal sheep at 101-104day gestation (term is 147days), compared to saline (n=8). JI-10 had no effect on fetal blood pressure, heart rate, carotid and femoral blood flow, total EEG power, nuchal activity, temperature or intracerebral oxygenation on near-infrared spectroscopy during or after occlusion. JI-10 was associated with later onset of post-asphyxial seizures compared with saline (p<0.05), and attenuation of the subsequent progressive loss of cytochrome oxidase (p<0.05). After 7days recovery, JI-10 was associated with improved neuronal survival in the caudate nucleus (p<0.05), but not the putamen or hippocampus, and more CNPase positive oligodendrocytes in the periventricular white matter (p<0.05). In conclusion, prophylactic nNOS inhibition before profound asphyxia was associated with delayed onset of seizures, slower decline of cytochrome oxidase and partial white and gray matter protection, consistent with protection of mitochondrial function. © 2013.

Partial Molar Volumes of 15-Crown-5 Ether in Mixtures of N,N-Dimethylformamide with Water.

PubMed

Tyczyńska, Magdalena; Jóźwiak, Małgorzata

2014-01-01

The density of 15-crown-5 ether (15C5) solutions in the mixtures of N,N -dimethylformamide (DMF) and water (H 2 O) was measured within the temperature range 293.15-308.15 K using an Anton Paar oscillatory U-tube densimeter. The results were used to calculate the apparent molar volumes ( V Φ ) of 15C5 in the mixtures of DMF + H 2 O over the whole concentration range. Using the apparent molar volumes and Redlich and Mayer equation, the standard partial molar volumes of 15-crown-5 were calculated at infinite dilution ([Formula: see text]). The limiting apparent molar expansibilities ( α ) were also calculated. The data are discussed from the point of view of the effect of concentration changes on interactions in solution.

Non-site-specific allosteric effect of oxygen on human hemoglobin under high oxygen partial pressure

PubMed Central

Takayanagi, Masayoshi; Kurisaki, Ikuo; Nagaoka, Masataka

2014-01-01

Protein allostery is essential for vital activities. Allosteric regulation of human hemoglobin (HbA) with two quaternary states T and R has been a paradigm of allosteric structural regulation of proteins. It is widely accepted that oxygen molecules (O2) act as a “site-specific” homotropic effector, or the successive O2 binding to the heme brings about the quaternary regulation. However, here we show that the site-specific allosteric effect is not necessarily only a unique mechanism of O2 allostery. Our simulation results revealed that the solution environment of high O2 partial pressure enhances the quaternary change from T to R without binding to the heme, suggesting an additional “non-site-specific” allosteric effect of O2. The latter effect should play a complementary role in the quaternary change by affecting the intersubunit contacts. This analysis must become a milestone in comprehensive understanding of the allosteric regulation of HbA from the molecular point of view. PMID:24710521

Non-site-specific allosteric effect of oxygen on human hemoglobin under high oxygen partial pressure.

PubMed

Takayanagi, Masayoshi; Kurisaki, Ikuo; Nagaoka, Masataka

2014-04-08

Protein allostery is essential for vital activities. Allosteric regulation of human hemoglobin (HbA) with two quaternary states T and R has been a paradigm of allosteric structural regulation of proteins. It is widely accepted that oxygen molecules (O2) act as a "site-specific" homotropic effector, or the successive O2 binding to the heme brings about the quaternary regulation. However, here we show that the site-specific allosteric effect is not necessarily only a unique mechanism of O2 allostery. Our simulation results revealed that the solution environment of high O2 partial pressure enhances the quaternary change from T to R without binding to the heme, suggesting an additional "non-site-specific" allosteric effect of O2. The latter effect should play a complementary role in the quaternary change by affecting the intersubunit contacts. This analysis must become a milestone in comprehensive understanding of the allosteric regulation of HbA from the molecular point of view.

Relationship between arterial partial oxygen pressure after resuscitation from cardiac arrest and mortality in children.

PubMed

Ferguson, Lee P; Durward, Andrew; Tibby, Shane M

2012-07-17

Observational studies in adults have shown a worse outcome associated with hyperoxia after resuscitation from cardiac arrest. Extrapolating from adult data, current pediatric resuscitation guidelines recommend avoiding hyperoxia. We investigated the relationship between arterial partial oxygen pressure and survival in patients admitted to the pediatric intensive care unit (PICU) after cardiac arrest. We conducted a retrospective cohort study using the Pediatric Intensive Care Audit Network (PICANet) database between 2003 and 2010 (n=122,521). Patients aged <16 years with documented cardiac arrest preceding PICU admission and arterial blood gas analysis taken within 1 hour of PICU admission were included. The primary outcome measure was death within the PICU. The relationship between postarrest oxygen status and outcome was modeled with logistic regression, with nonlinearities explored via multivariable fractional polynomials. Covariates included age, sex, ethnicity, congenital heart disease, out-of-hospital arrest, year, Pediatric Index of Mortality-2 (PIM2) mortality risk, and organ supportive therapies. Of 1875 patients, 735 (39%) died in PICU. Based on the first arterial gas, 207 patients (11%) had hyperoxia (Pa(O)(2) ≥300 mm Hg) and 448 (24%) had hypoxia (Pa(O)(2) <60 mm Hg). We found a significant nonlinear relationship between Pa(O)(2) and PICU mortality. After covariate adjustment, risk of death increased sharply with increasing hypoxia (odds ratio, 1.92; 95% confidence interval, 1.80-2.21 at Pa(O)(2) of 23 mm Hg). There was also an association with increasing hyperoxia, although not as dramatic as that for hypoxia (odds ratio, 1.25; 95% confidence interval, 1.17-1.37 at 600 mm Hg). We observed an increasing mortality risk with advancing age, which was more pronounced in the presence of congenital heart disease. Both severe hypoxia and, to a lesser extent, hyperoxia are associated with an increased risk of death after PICU admission after cardiac arrest.

An N-methyl-D-aspartate receptor-independent excitatory action of partial reduction of extracellular [Mg2+] in CA1-region of rat hippocampal slices.

PubMed

Hamon, B; Stanton, P K; Heinemann, U

1987-03-31

Partial reduction of [Mg2+]o from 2 to 1 mM markedly enhanced neuronal responses evoked by Schaffer collateral-commissural fiber stimulation in the CA1-region of rat hippocampal slices. The amplitude of extracellular population potentials recorded in the CA1-pyramidal cell layer and maximum dV/dt of extracellular population EPSP's recorded in the CA1-pyramidal apical dendritic layer were both increased. However, unlike findings from slices where Mg2+ was completely removed from the bathing medium, there was no spontaneous or evoked epileptiform activity, and the N-methyl-D-aspartate (NMDA) receptor antagonist 2-amino-5-phosphonovalerate (2-APV) did not antagonize the enhancement of evoked responses. These results indicate that, in addition to the participation of NMDA receptors in the epileptiform activity observed when Mg2+ is completely removed from the bathing medium, there is also an NMDA receptor-independent excitatory action of partial reduction of [Mg2+]o in hippocampal slices.

Characterization of Ar/N2/H2 middle-pressure RF discharge and application of the afterglow region for nitridation of GaAs

NASA Astrophysics Data System (ADS)

Raud, J.; Jõgi, I.; Matisen, L.; Navrátil, Z.; Talviste, R.; Trunec, D.; Aarik, J.

2017-12-01

This work characterizes the production and destruction of nitrogen and hydrogen atoms in RF capacitively coupled middle-pressure discharge in argon/nitrogen/hydrogen mixtures. Input power, electron concentration, electric field strength and mean electron energy were determined on the basis of electrical measurements. Gas temperature and concentration of Ar atoms in 1s states were determined from spectral measurements. On the basis of experimentally determined plasma characteristics, main production and loss mechanisms of H and N atoms were discussed. The plasma produced radicals were applied for the nitridation and oxide reduction of gallium arsenide in the afterglow region of discharge. After plasma treatment the GaAs samples were analyzed using x-ray photoelectron spectroscopy (XPS) technique. Successful nitridation of GaAs sample was obtained in the case of Ar/5% N2 discharge. In this gas mixture the N atoms were generated via dissociative recombination of N2+ created by charge transfer from Ar+. The treatment in Ar/5% N2/1% H2 mixture resulted in the reduction of oxide signals in the XPS spectra. Negligible formation of GaN in the latter mixture was connected with reduced concentration of N atoms, which was, in turn, due to less efficient mechanism of N atom production (electron impact dissociation of N2 molecules) and additional loss channel in reaction with H2.

Effect of Partial Pressure of Oxygen and Activity of Carbon on the Corrosion of High Temperature Alloys in s-CO2 Environments

NASA Astrophysics Data System (ADS)

Mahaffey, Jacob Thomas

Over the course of the past couple decades, increased concern has grown on the topics of climate change and energy consumption, focusing primarily on carbon emissions. With modernization of countries like India and China, there are no signs of slowing of global carbon emissions and energy usage. To combat this, new more efficient power conversion cycles must be utilized. The Supercritical Carbon Dioxide (s-CO2) Brayton cycle promises increased efficiency and smaller component sizes. These cycles will push the limits of current high temperature materials, and must be studied before implementation is made possible. A large collection of high temperature CO2 corrosion research has been reported over the last thirty years. While many of the studies in the past have focused on corrosion in research grade (RG) (99.999%) and industrial grade (IG) (99.5%) CO2, very few have focused on studying the specific effects that impurities can have on the corrosion rates and mechanisms. The work described in this document will lay the foundation for advancement of s-CO2 corrosion studies. A testing facility has been constructed and was designed as an open flow s-CO2 loop with a fluid residence time of 2 hours. This facility is capable of heating up to 750°C at pressures up to 20 MPa. Instrumentation for monitoring oxygen and carbon monoxide concentration were added to make measurements both before and after sample exposure, for the duration of testing. Testing of both model and commercial alloys was conducted for temperatures ranging from 450-750°C at 20MPa for 1,000 hours. The effect of the partial pressure of oxygen (pO2) was studied by adding 100ppm of O2 to RG CO2 during testing. The activity of carbon (aC) was studied by adding 1%CO to RG CO2. Each environment greatly altered the mechanisms and rates of oxidation and carburization on each material exposed to the environment.

Two Phase Flow Modeling: Summary of Flow Regimes and Pressure Drop Correlations in Reduced and Partial Gravity

NASA Technical Reports Server (NTRS)

Balasubramaniam, R.; Rame, E.; Kizito, J.; Kassemi, M.

2006-01-01

The purpose of this report is to provide a summary of state-of-the-art predictions for two-phase flows relevant to Advanced Life Support. We strive to pick out the most used and accepted models for pressure drop and flow regime predictions. The main focus is to identify gaps in predictive capabilities in partial gravity for Lunar and Martian applications. Following a summary of flow regimes and pressure drop correlations for terrestrial and zero gravity, we analyze the fully developed annular gas-liquid flow in a straight cylindrical tube. This flow is amenable to analytical closed form solutions for the flow field and heat transfer. These solutions, valid for partial gravity as well, may be used as baselines and guides to compare experimental measurements. The flow regimes likely to be encountered in the water recovery equipment currently under consideration for space applications are provided in an appendix.

Inaccuracy of a physical strain trainer for the monitoring of partial weight bearing.

PubMed

Pauser, Johannes; Jendrissek, Andreas; Swoboda, Bernd; Gelse, Kolja; Carl, Hans-Dieter

2011-11-01

To investigate the use of a physical strain trainer for the monitoring of partial weight bearing. Case series with healthy volunteers. Orthopedic clinic. Healthy volunteers (N=10) with no history of foot complaints. Volunteers were taught to limit weight bearing to 10% body weight (BW) and 50% BW, monitored by a physical strain trainer. The parameters peak pressure, maximum force, force-time integral, and pressure-time integral were assessed by dynamic pedobarography when volunteers walked with full BW (condition 1), 50% BW (condition 2), and 10% BW (condition 3). With 10% BW (condition 3), forces with normative gait (condition 1) were statistically significantly reduced under the hindfoot where the physical strain trainer is placed. All pedobarographic parameters were, however, exceeded when the total foot was measured. A limitation to 10% BW with the physical strain trainer (condition 3) was equal to a bisection of peak pressure and maximum force for the total foot with normative gait (condition 1). Halved BW (condition 2) left a remaining mean 82% of peak pressure and mean 59% of maximum force from full BW (condition 1). The concept of controlling partial weight bearing with the hindfoot-addressing device does not represent complete foot loading. Such devices may be preferably applied in cases when the hindfoot in particular must be off-loaded. Other training devices (eg, biofeedback soles) that monitor forces of the total foot have to be used to control partial weight bearing of the lower limb accurately. Copyright © 2011 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Electrical and optical properties of nitrogen doped SnO{sub 2} thin films deposited on flexible substrates by magnetron sputtering

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

Fang, Feng, E-mail: fangfeng@seu.edu.cn; Zhang, Yeyu; Wu, Xiaoqin

2015-08-15

Graphical abstract: The best SnO{sub 2}:N TCO film: about 80% transmittance and 9.1 × 10{sup −4} Ω cm. - Highlights: • Nitrogen-doped tin oxide film was deposited on PET by RF-magnetron sputtering. • Effects of oxygen partial pressure on the properties of thin films were investigated. • For SnO{sub 2}:N film, visible light transmittance was 80% and electrical resistivity was 9.1 × 10{sup −4} Ω cm. - Abstract: Nitrogen-doped tin oxide (SnO{sub 2}:N) thin films were deposited on flexible polyethylene terephthalate (PET) substrates at room temperature by RF-magnetron sputtering. Effects of oxygen partial pressure (0–4%) on electrical and optical propertiesmore » of thin films were investigated. Experimental results showed that SnO{sub 2}:N films were amorphous state, and O/Sn ratios of SnO{sub 2}:N films were deviated from the standard stoichiometry 2:1. Optical band gap of SnO{sub 2}:N films increased from approximately 3.10 eV to 3.42 eV as oxygen partial pressure increased from 0% to 4%. For SnO{sub 2}:N thin films deposited on PET, transmittance was about 80% in the visible light region. The best transparent conductive oxide (TCO) deposited on flexible PET substrates was SnO{sub 2}:N thin films preparing at 2% oxygen partial pressure, the transmittance was about 80% and electrical conductivity was about 9.1 × 10{sup −4} Ω cm.« less

Two-photon high-resolution measurement of partial pressure of oxygen in cerebral vasculature and tissue.

PubMed

Sakadzić, Sava; Roussakis, Emmanuel; Yaseen, Mohammad A; Mandeville, Emiri T; Srinivasan, Vivek J; Arai, Ken; Ruvinskaya, Svetlana; Devor, Anna; Lo, Eng H; Vinogradov, Sergei A; Boas, David A

2010-09-01

Measurements of oxygen partial pressure (pO(2)) with high temporal and spatial resolution in three dimensions is crucial for understanding oxygen delivery and consumption in normal and diseased brain. Among existing pO(2) measurement methods, phosphorescence quenching is optimally suited for the task. However, previous attempts to couple phosphorescence with two-photon laser scanning microscopy have faced substantial difficulties because of extremely low two-photon absorption cross-sections of conventional phosphorescent probes. Here we report to our knowledge the first practical in vivo two-photon high-resolution pO(2) measurements in small rodents' cortical microvasculature and tissue, made possible by combining an optimized imaging system with a two-photon-enhanced phosphorescent nanoprobe. The method features a measurement depth of up to 250 microm, sub-second temporal resolution and requires low probe concentration. The properties of the probe allowed for direct high-resolution measurement of cortical extravascular (tissue) pO(2), opening many possibilities for functional metabolic brain studies.

The Role of 5-HT2A, 5-HT2C and mGlu2 Receptors in the Behavioral Effects of Tryptamine Hallucinogens N,N-Dimethyltryptamine and N,N-Diisopropyltryptamine in Rats and Mice

PubMed Central

Carbonaro, Theresa M.; Eshleman, Amy J.; Forster, Michael J.; Cheng, Kejun; Rice, Kenner C.; Gatch, Michael B.

2014-01-01

Rationale: Serotonin 5-HT2A and 5-HT2C receptors are thought to be the primary pharmacological mechanisms for serotonin-mediated hallucinogenic drugs, but recently there has been interest in metabotropic glutamate (mGluR2) receptors as contributors to the mechanism of hallucinogens. Objective: The present study assesses the role of these 5-HT and glutamate receptors as molecular targets for two tryptamine hallucinogens, N,N-dimethyltryptamine (DMT) and N,N-diisopropyltryptamine (DiPT). Methods: Drug discrimination, head twitch and radioligand binding assays were used. A 5-HT2AR inverse agonist (MDL100907), 5-HT2CR antagonist (SB242084) and mGluR2/3 agonist (LY379268) were tested for their ability to attenuate the discriminative stimulus effects of DMT and DiPT; an mGluR2/3 antagonist (LY341495) was tested for potentiation. MDL100907 was used to attenuate head twitches induced by DMT and DiPT. Radioligand binding studies and inosital-1-phosphate (IP-1) accumulation were performed at the 5-HT2CR for DiPT. Results: MDL100907 fully blocked the discriminative stimulus effects of DMT, but only partially blocked DiPT. SB242084 partially attenuated the discriminative stimulus effects of DiPT, but produced minimal attenuation of DMT’s effects. LY379268 produced potent, but only partial blockade of the discriminative stimulus effects of DMT. LY341495 facilitated DMT- and DiPT-like effects. Both compounds elicited head twitches (DiPT>DMT) which were blocked by MDL1000907. DiPT was a low potency full agonist at 5-HT2CR in vitro. Conclusions: The 5-HT2AR likely plays a major role in mediating the effects of both compounds. 5-HT2C and mGluR2 receptors likely modulate the discriminative stimulus effects of both compounds to some degree. PMID:24985890

The role of 5-HT2A, 5-HT 2C and mGlu2 receptors in the behavioral effects of tryptamine hallucinogens N,N-dimethyltryptamine and N,N-diisopropyltryptamine in rats and mice.

PubMed

Carbonaro, Theresa M; Eshleman, Amy J; Forster, Michael J; Cheng, Kejun; Rice, Kenner C; Gatch, Michael B

2015-01-01

Serotonin 5-HT2A and 5-HT2C receptors are thought to be the primary pharmacological mechanisms for serotonin-mediated hallucinogenic drugs, but recently there has been interest in metabotropic glutamate (mGluR2) receptors as contributors to the mechanism of hallucinogens. The present study assesses the role of these 5-HT and glutamate receptors as molecular targets for two tryptamine hallucinogens, N,N-dimethyltryptamine (DMT) and N,N-diisopropyltryptamine (DiPT). Drug discrimination, head twitch, and radioligand binding assays were used. A 5-HT2AR inverse agonist (MDL100907), 5-HT2CR antagonist (SB242084), and mGluR2/3 agonist (LY379268) were tested for their ability to attenuate the discriminative stimulus effects of DMT and DiPT; an mGluR2/3 antagonist (LY341495) was tested for potentiation. MDL100907 was used to attenuate head twitches induced by DMT and DiPT. Radioligand binding studies and inosital-1-phosphate (IP-1) accumulation were performed at the 5-HT2CR for DiPT. MDL100907 fully blocked the discriminative stimulus effects of DMT, but only partially blocked DiPT. SB242084 partially attenuated the discriminative stimulus effects of DiPT, but produced minimal attenuation of DMT's effects. LY379268 produced potent, but only partial blockade of the discriminative stimulus effects of DMT. LY341495 facilitated DMT- and DiPT-like effects. Both compounds elicited head twitches (DiPT>DMT) which were blocked by MDL1000907. DiPT was a low-potency full agonist at 5-HT2CR in vitro. The 5-HT2AR likely plays a major role in mediating the effects of both compounds. 5-HT2C and mGluR2 receptors likely modulate the discriminative stimulus effects of both compounds to some degree.

Real-Time Optical Monitoring and Simulations of Gas Phase Kinetics in InN Vapor Phase Epitaxy at High Pressure

NASA Technical Reports Server (NTRS)

Dietz, Nikolaus; Woods, Vincent; McCall, Sonya D.; Bachmann, Klaus J.

2003-01-01

Understanding the kinetics of nucleation and coalescence of heteroepitaxial thin films is a crucial step in controlling a chemical vapor deposition process, since it defines the perfection of the heteroepitaxial film both in terms of extended defect formation and chemical integrity of the interface. The initial nucleation process also defines the film quality during the later stages of film growth. The growth of emerging new materials heterostructures such as InN or In-rich Ga(x)In(1-x)N require deposition methods operating at higher vapor densities due to the high thermal decomposition pressure in these materials. High nitrogen pressure has been demonstrated to suppress thermal decomposition of InN, but has not been applied yet in chemical vapor deposition or etching experiments. Because of the difficulty with maintaining stochiometry at elevated temperature, current knowledge regarding thermodynamic data for InN, e.g., its melting point, temperature-dependent heat capacity, heat and entropy of formation are known with far less accuracy than for InP, InAs and InSb. Also, no information exists regarding the partial pressures of nitrogen and phosphorus along the liquidus surfaces of mixed-anion alloys of InN, of which the InN(x)P(1-x) system is the most interesting option. A miscibility gap is expected for InN(x)P(1-x) pseudobinary solidus compositions, but its extent is not established at this point by experimental studies under near equilibrium conditions. The extension of chemical vapor deposition to elevated pressure is also necessary for retaining stoichiometric single phase surface composition for materials that are characterized by large thermal decomposition pressures at optimum processing temperatures.

Alteration of a recombinant protein N-glycan structure in silkworms by partial suppression of N-acetylglucosaminidase gene expression.

PubMed

Kato, Tatsuya; Kikuta, Kotaro; Kanematsu, Ayumi; Kondo, Sachiko; Yagi, Hirokazu; Kato, Koichi; Park, Enoch Y

2017-09-01

To synthesize complex type N-glycans in silkworms, shRNAs against the fused lobe from Bombyx mori (BmFDL), which codes N-acetylglucosaminidase (GlcNAcase) in the Golgi, was expressed by recombinant B. mori nucleopolyhedrovirus (BmNPV) in silkworm larvae. Expression was under the control of the actin promoter of B. mori or the U6-2 and i.e.-2 promoters from Orgyia pseudotsugata multiple nucleopolyhedrovirus (OpMNPV). The reduction of specific GlcNAcase activity was observed in Bm5 cells and silkworm larvae using the U6-2 promoter. In silkworm larvae, the partial suppression of BmFDL gene expression was observed. When shRNA against BmFDL was expressed under the control of U6-2 promoter, the Man 3 GlcNAc(Fuc)GlcNAc structure appeared in a main N-glycans of recombinant human IgG. These results suggested that the control of BmFDL expression by its shRNA in silkworms caused the modification of its N-glycan synthetic pathway, which may lead to the alteration of N-glycans in the expressed recombinant proteins. Suppression of BmFDL gene expression by shRNA is not sufficient to synthesize complex N-glycans in silkworm larvae but can modify the N-glycan synthetic pathway.

High Oxygen Partial Pressure Decreases Anemia-Induced Heart Rate Increase Equivalent to Transfusion

PubMed Central

Feiner, John R.; Finlay-Morreale, Heather E.; Toy, Pearl; Lieberman, Jeremy A.; Viele, Maurene K.; Hopf, Harriet W.; Weiskopf, Richard B.

2011-01-01

Background Anemia is associated with morbidity and mortality and frequently leads to transfusion of erythrocytes. We sought to compare directly the effect of high inspired oxygen fraction vs. transfusion of erythrocytes on the anemia-induced increased heart rate (HR) in humans undergoing experimental acute isovolemic anemia. Methods We combined HR data from healthy subjects undergoing experimental isovolemic anemia in seven studies performed by our group. We examined HR changes associated with breathing 100% oxygen by non-rebreathing face mask vs. transfusion of erythrocytes at their nadir hemoglobin (Hb) concentration of 5 g/dL. Data were analyzed using a mixed-effects model. Results HR had an inverse linear relationship to hemoglobin concentration with a mean increase of 3.9 beats per minute per gram of Hb (beats/min/g Hb) decrease (95% confidence interval [CI], 3.7 – 4.1 beats/min/g Hb), P < 0.0001. Return of autologous erythrocytes significantly decreased HR by 5.3 beats/min/g Hb (95% CI, 3.8 – 6.8 beats/min/g Hb) increase, P < 0.0001. HR at nadir Hb of 5.6 g/dL (95% CI, 5.5 – 5.7 g/dL) when breathing air (91.4 beats/min; 95% CI, 87.6 – 95.2 beats/min) was reduced by breathing 100% oxygen (83.0 beats/min; 95% CI, 79.0 -87.0 beats/min), P < 0.0001. The HR at hemoglobin 5.6 g/dL when breathing oxygen was equivalent to the HR at Hb 8.9 g/dL when breathing air. Conclusions High arterial oxygen partial pressure reverses the heart rate response to anemia, probably owing to its usability, rather than its effect on total oxygen content. The benefit of high arterial oxygen partial pressure has significant potential clinical implications for the acute treatment of anemia and results of transfusion trials. PMID:21768873

Pressure-induced enhancement in the thermoelectric properties of monolayer and bilayer SnSe2

NASA Astrophysics Data System (ADS)

Zou, Daifeng; Yu, Chuanbin; Li, Yuhao; Ou, Yun; Gao, Yongyi

2018-03-01

The electronic structures of monolayer and bilayer SnSe2 under pressure were investigated by using first-principles calculations including van der Waals interactions. For monolayer SnSe2, the variation of electronic structure under pressure is controlled by pressure-dependent lattice parameters. For bilayer SnSe2, the changes in electronic structure under pressure are dominated by intralayer and interlayer atomic interactions. The n-type thermoelectric properties of monolayer and bilayer SnSe2 under pressure were calculated on the basis of the semi-classical Boltzmann transport theory. It was found that the electrical conductivity of monolayer and bilayer SnSe2 can be enhanced under pressure, and such dependence can be attributed to the pressure-induced changes of the Se-Sn antibonding states in conduction band. Finally, the doping dependence of power factors of n-type monolayer and bilayer SnSe2 at three different pressures were estimated, and the results unveiled that thermoelectric performance of n-type monolayer and bilayer SnSe2 can be improved by applying external pressure. This study benefits to understand the nature of the transport properties for monolayer and bilayer SnSe2 under pressure, and it offers valuable insight for designing high-performance thermoelectric few-layered SnSe2 through strain engineering induced by external pressure.

High-Pressure CO2 Sorption in Polymers of Intrinsic Microporosity under Ultrathin Film Confinement.

PubMed

Ogieglo, Wojciech; Ghanem, Bader; Ma, Xiaohua; Wessling, Matthias; Pinnau, Ingo

2018-04-04

Ultrathin microporous polymer films are pertinent to the development and further spread of nanotechnology with very promising potential applications in molecular separations, sensors, catalysis, or batteries. Here, we report high-pressure CO 2 sorption in ultrathin films of several chemically different polymers of intrinsic microporosity (PIMs), including the prototypical PIM-1. Films with thicknesses down to 7 nm were studied using interference-enhanced in situ spectroscopic ellipsometry. It was found that all PIMs swell much more than non-microporous polystyrene and other high-performance glassy polymers reported previously. Furthermore, chemical modifications of the parent PIM-1 strongly affected the swelling magnitude. By investigating the behavior of relative refractive index, n rel , it was possible to study the interplay between micropores filling and matrix expansion. Remarkably, all studied PIMs showed a maximum in n rel at swelling of 2-2.5% indicating a threshold point above which the dissolution in the dense matrix started to dominate over sorption in the micropores. At pressures above 25 bar, all PIMs significantly plasticized in compressed CO 2 and for the ones with the highest affinity to the penetrant, a liquidlike mixing typical for rubbery polymers was observed. Reduction of film thickness below 100 nm revealed pronounced nanoconfinement effects and resulted in a large swelling enhancement and a quick loss of the ultrarigid character. On the basis of the partial molar volumes of the dissolved CO 2 , the effective reduction of the T g was estimated to be ∼200 °C going from 128 to 7 nm films.

In-Situ Electrochemical Corrosion Behavior of Nickel-Base 718 Alloy Under Various CO2 Partial Pressures at 150 and 205 °C in NaCl Solution

NASA Astrophysics Data System (ADS)

Zhang, Yubi; Zhao, Yongtao; Tang, An; Yang, Wenjie; Li, Enzuo

2018-07-01

The electrochemical corrosion behavior of nickel-base alloy 718 was investigated using electrochemical impedance spectroscopy and potentiodynamic polarization techniques at various partial pressures of CO2 (P_{{{CO}2 }}s) in a 25 wt% NaCl solution at 150 and 205 °C. The passive films composed of FeCO3 exhibit good corrosion resistance with a feature of Warburg impedance, Tafel plots show a complete passivation and the anodic reactions was dominated by a diffusion process at low P_{{{CO}2 }}s (1.8-9.8 MPa) at 150 °C. While numerous dented corrosion areas appeared on the sample surface for the P_{{{CO}2 }} of 11.6 MPa at 205 °C, the Tafel plot with three anodic peaks and the Nyquist diagram with an atrophied impedance arc were present. This dented corrosion attribute to the synergistic effects of stress, temperature, P_{{{CO}2 }} and Cl-, the temperature and stress could play crucial roles on the corrosion of the alloy 718.

In-Situ Electrochemical Corrosion Behavior of Nickel-Base 718 Alloy Under Various CO2 Partial Pressures at 150 and 205 °C in NaCl Solution

NASA Astrophysics Data System (ADS)

Zhang, Yubi; Zhao, Yongtao; Tang, An; Yang, Wenjie; Li, Enzuo

2018-03-01

The electrochemical corrosion behavior of nickel-base alloy 718 was investigated using electrochemical impedance spectroscopy and potentiodynamic polarization techniques at various partial pressures of CO2 (P_{{{CO}2 }} s) in a 25 wt% NaCl solution at 150 and 205 °C. The passive films composed of FeCO3 exhibit good corrosion resistance with a feature of Warburg impedance, Tafel plots show a complete passivation and the anodic reactions was dominated by a diffusion process at low P_{{{CO}2 }} s (1.8-9.8 MPa) at 150 °C. While numerous dented corrosion areas appeared on the sample surface for the P_{{{CO}2 }} of 11.6 MPa at 205 °C, the Tafel plot with three anodic peaks and the Nyquist diagram with an atrophied impedance arc were present. This dented corrosion attribute to the synergistic effects of stress, temperature, P_{{{CO}2 }} and Cl-, the temperature and stress could play crucial roles on the corrosion of the alloy 718.

Determination of the Rate Constants for the NH 2 (X 2 B 1 ) + NH 2 (X 2 B 1 ) and NH 2 (X 2 B 1 ) + H Recombination Reactions in N 2 as a Function of Temperature and Pressure

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

Altinay, Gokhan; Macdonald, R. Glen

2015-07-16

The recombination rate constants for the reactions NH2 + NH2 → N2H4 (reaction k1b) and NH2 + H → NH3 (reaction k2b) with N2 as a third-body have been measured as a function of temperature and pressure. The temperature range was from 292 to 533 K and the pressure range from a few Torr up to 300–400 Torr, well within the pressure falloff region. The NH2 radical was produced by 193 nm pulsed-laser photolysis of NH3 in a temperature controlled flow chamber. High-resolution time-resolved laser absorption spectroscopy was used to follow the temporal concentration profiles of both NH2 and NH3, simultaneously. The NH2 radical was monitored at 14800.65 cm–1 using the 1231 (0,7,0)Ã2A1 ← 1331 (0,0,0)more » $$\\tilde{X}$$2B1 ro-vibronic transition, and NH3 monitored at 3336.39 cm–1 on the qQ3(3)s (1,0,0,0) ← (0,0,0,0) ro-vibrational transition. The necessary collisional broadening parameters for each molecule were measured in separate experiments. The pressure and temperature dependence of k1b can be represented by the Troe parameters: k0, the low-pressure three-body recombination rate constant, k0(T) = (1.14 ± 0.59) × 10–19T–(3.41±0.28) cm6 molecule–2 s–1, and Fcent, the pressure broadening parameter, Fcent = 0.15 ± 0.12, independent of temperature. The data could not be fit by three-independent parameters, and the high-pressure limiting rate constant k∞(T) = 9.33 × 10–10T–0.414 e33/T cm3 molecule–1 s–1 was taken from the high-quality theoretical calculations of Klippenstein et al. (J. Phys. Chem A 2009, 113, 10241). The pressure and temperature dependence of k2b, can be represented by the Troe parameters: k0(T) = (9.95 ± 0.58) × 10–26T(-1.76±0.092) cm6 molecule–2 s–1, Fcent = 0.5 ± 0.2, k∞ = 2.6 × 10–10 cm3 molecule–1 s–1. Again, the data could not be fit with three independent parameters, and k2b∞ was chosen to be 2.6 × 10–10 cm3 molecule–1 s–1 and fixed in the analysis.« less

The Role of the Pressure in the Partial Regularity Theory for Weak Solutions of the Navier-Stokes Equations

NASA Astrophysics Data System (ADS)

Chamorro, Diego; Lemarié-Rieusset, Pierre-Gilles; Mayoufi, Kawther

2018-04-01

We study the role of the pressure in the partial regularity theory for weak solutions of the Navier-Stokes equations. By introducing the notion of dissipative solutions, due to D uchon and R obert (Nonlinearity 13:249-255, 2000), we will provide a generalization of the Caffarelli, Kohn and Nirenberg theory. Our approach sheels new light on the role of the pressure in this theory in connection to Serrin's local regularity criterion.

Standard partial molar volumes of some aqueous alkanolamines and alkoxyamines at temperatures up to 325 degrees C: functional group additivity in polar organic solutes under hydrothermal conditions.

PubMed

Bulemela, E; Tremaine, Peter R

2008-05-08

Apparent molar volumes of dilute aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), N,N-dimethylethanolamine (DMEA), ethylethanolamine (EAE), 2-diethylethanolamine (2-DEEA), and 3-methoxypropylamine (3-MPA) and their salts were measured at temperatures from 150 to 325 degrees C and pressures as high as 15 MPa. The results were corrected for the ionization and used to obtain the standard partial molar volumes, Vo2. A three-parameter equation of state was used to describe the temperature and pressure dependence of the standard partial molar volumes. The fitting parameters were successfully divided into functional group contributions at all temperatures to obtain the standard partial molar volume contributions. Including literature results for alcohols, carboxylic acids, and hydroxycarboxylic acids yielded the standard partial molar volume contributions of the functional groups >CH-, >CH2, -CH3, -OH, -COOH, -O-, -->N, >NH, -NH2, -COO-Na+, -NH3+Cl-, >NH2+Cl-, and -->NH+Cl- over the range (150 degrees C partial molar volume of aqueous organic solutes composed of these groups at temperatures up to approximately 310 degrees C and pressures of 10-20 MPa to within a precision of +/-5 cm3 x mol(-1). The model could not be extended to higher temperatures because of uncertainties caused by thermal decomposition. At temperatures above approximately 250 degrees C, the order of the group contributions to Vo2 changes from that observed at 25 degrees C, to become increasingly consistent with the polarity of each functional group. The effect of the dipole moment of each molecule on the contribution to Vo2 from long-range solvent polarization was calculated from the multipole expansion of the Born equation using dipole moments estimated from restricted Hartree-Fock calculations with Gaussian 03 (Gaussian, Inc., Wallingford, CT) and the Onsager reaction-field approximation for

Effect of Nickel Levels on Hydrogen Partial Pressure and Methane Production in Methanogens

PubMed Central

2016-01-01

Hydrogen (H2) consumption and methane (CH4) production in pure cultures of three different methanogens were investigated during cultivation with 0, 0.2 and 4.21 μM added nickel (Ni). The results showed that the level of dissolved Ni in the anaerobic growth medium did not notably affect CH4 production in the cytochrome-free methanogenic species Methanobacterium bryantii and Methanoculleus bourgensis MAB1, but affected CH4 formation rate in the cytochrome-containing Methanosarcina barkeri grown on H2 and CO2. Methanosarcina barkeri also had the highest amounts of Ni in its cells, indicating that more Ni is needed by cytochrome-containing than by cytochrome-free methanogenic species. The concentration of Ni affected threshold values of H2 partial pressure (pH2) for all three methanogen species studied, with M. bourgensis MAB1 reaching pH2 values as low as 0.1 Pa when Ni was available in amounts used in normal anaerobic growth medium. To our knowledge, this is the lowest pH2 threshold recorded to date in pure methanogen culture, which suggests that M.bourgensis MAB1 have a competitive advantage over other species through its ability to grow at low H2 concentrations. Our study has implications for research on the H2-driven deep subsurface biosphere and biogas reactor performance. PMID:27992585

Effect of Nickel Levels on Hydrogen Partial Pressure and Methane Production in Methanogens.

PubMed

Neubeck, Anna; Sjöberg, Susanne; Price, Alex; Callac, Nolwenn; Schnürer, Anna

2016-01-01

Hydrogen (H2) consumption and methane (CH4) production in pure cultures of three different methanogens were investigated during cultivation with 0, 0.2 and 4.21 μM added nickel (Ni). The results showed that the level of dissolved Ni in the anaerobic growth medium did not notably affect CH4 production in the cytochrome-free methanogenic species Methanobacterium bryantii and Methanoculleus bourgensis MAB1, but affected CH4 formation rate in the cytochrome-containing Methanosarcina barkeri grown on H2 and CO2. Methanosarcina barkeri also had the highest amounts of Ni in its cells, indicating that more Ni is needed by cytochrome-containing than by cytochrome-free methanogenic species. The concentration of Ni affected threshold values of H2 partial pressure (pH2) for all three methanogen species studied, with M. bourgensis MAB1 reaching pH2 values as low as 0.1 Pa when Ni was available in amounts used in normal anaerobic growth medium. To our knowledge, this is the lowest pH2 threshold recorded to date in pure methanogen culture, which suggests that M.bourgensis MAB1 have a competitive advantage over other species through its ability to grow at low H2 concentrations. Our study has implications for research on the H2-driven deep subsurface biosphere and biogas reactor performance.

Thermodynamics of a Magnetic Transition in MnS2 at High Pressures

NASA Astrophysics Data System (ADS)

Sidorov, V. A.; Guo, Jing; Sun, Liling; Brazhkin, V. V.

2018-03-01

The behavior of the specific heat of MnS2 at high pressures has been studied. A significant increase in the transition temperature T N to an antiferromagnetic state with the pressure from 48.2 K at atmospheric pressure to 76 K at a pressure of 5.3 GPa has been revealed. The initial pressure derivative is dT N / dP = 4.83 K/GPa. It has been found that the parameter α = d(log T N )/ d(log V ) = -6.6 ± 0.1 is significantly different from the value α = -10/3 ≈ -3.3 (Bloch relation), which is typical of numerous antiferromagnetic insulators—transition- metal oxides and fluorides. The volume jump at the magnetic transition point has been estimated. The necessity of direct dilatometric measurements of the volume has been justified.

Inerting of magnesium dust cloud with Ar, N2 and CO2.

PubMed

Li, G; Yuan, C M; Fu, Y; Zhong, Y P; Chen, B Z

2009-10-15

Experiments were conducted on the inerting of magnesium dust with N(2), CO(2), and Ar. Comparing the maximum explosion pressure, maximum rate of pressure rise, and limiting oxygen concentration with different inertants, it was determined that Ar is not the best inert gas under all conditions as commonly believed. N(2) was more effective than Ar as an inertant. CO(2) provided more inerting effect than either Ar and N(2) in low magnesium dust concentrations, although explosibility was increased at higher dust concentrations. Both N(2) and CO(2) as inerting agents showed higher LOC values than Ar. These results indicated that N(2) is a more economical inerting gas than Ar for the tested coarse magnesium dust.

Influence of oxygen partial pressure on surface tension and its temperature coefficient of molten iron

NASA Astrophysics Data System (ADS)

Ozawa, S.; Suzuki, S.; Hibiya, T.; Fukuyama, H.

2011-01-01

Influences of oxygen partial pressure, PO2, of ambient atmosphere and temperature on surface tension and its temperature coefficient for molten iron were experimentally investigated by an oscillating droplet method using an electromagnetic levitation furnace. We successfully measured the surface tension of molten iron over a very wide temperature range of 780 K including undercooling condition in a well controlled PO2 atmosphere. When PO2 is fixed at 10-2 Pa at the inlet of the chamber, a "boomerang shape" temperature dependence of surface tension was experimentally observed; surface tension increased and then decreased with increasing temperature. The pure surface tension of molten iron was deduced from the negative temperature coefficient in the boomerang shape temperature dependence. When the surface tension was measured under the H2-containing gas atmosphere, surface tension did not show a linear relationship against temperature. The temperature dependence of the surface tension shows anomalous kink at around 1850 K due to competition between the temperature dependence of PO2 and that of the equilibrium constant of oxygen adsorption.

Highly oriented NdFeCoB nanocrystalline magnets from partially disproportionated compacts by reactive deformation under low pressure

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

Zheng, Qing; Li, Jun; Liu, Ying, E-mail: liuying5536@163.com

2014-05-07

In the present investigation, we take advantage of the ultrafine grain size of NdFeCoB partially hydrogen-disproportionated phases, and prepare anisotropic nanocrystalline magnets with full density and homogenous microstructure and texture by reactive deformation under low pressure. Our results suggest that the pressure could properly promote an occurrence of desorption-recombination reaction due to a shorter-range rearrangement of the atoms, and the newly recombined Nd{sub 2}Fe{sub 14}B grains with fine grain size could undergo deformation immediately after the phase transformation, and then an obvious anisotropy and uniform alignment would be obtained. The maximum magnetic properties, (BH){sub max} = 25.8 MGOe, Br = 11.8 kG, H{sub cj} = 5.5more » kOe, were obtained after being treated for 5 min at 820 °C in vacuum. The present study highlights the feasibility to prepare anisotropic nanocrystalline magnets with homogeneous microstructure and a strong (00l) texture of uniform grain size under low pressure.« less

Non-contact measurement of partial gas pressure and distribution of elemental composition using energy-resolved neutron imaging

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

Tremsin, A. S.; Losko, A. S.; Vogel, S. C.

Neutron resonance absorption imaging is a non-destructive technique that can characterize the elemental composition of a sample by measuring nuclear resonances in the spectrum of a transmitted beam. Recent developments in pixelated time-of-flight imaging detectors coupled with pulsed neutron sources pose new opportunities for energy-resolved imaging. In this paper we demonstrate non-contact measurements of the partial pressure of xenon and krypton gases encapsulated in a steel pipe while simultaneously passing the neutron beam through high-Z materials. The configuration was chosen as a proof of principle demonstration of the potential to make non-destructive measurement of gas composition in nuclear fuel rods.more » The pressure measured from neutron transmission spectra (~739 ± 98 kPa and ~751 ± 154 kPa for two Xe resonances) is in relatively good agreement with the pressure value of ~758 ± 21 kPa measured by a pressure gauge. This type of imaging has been performed previously for solids with a spatial resolution of ~ 100 μm. In the present study it is demonstrated that the high penetration capability of epithermal neutrons enables quantitative mapping of gases encapsulate within high-Z materials such as steel, tungsten, urania and others. This technique may be beneficial for the non-destructive testing of bulk composition of objects (such as spent nuclear fuel assemblies and others) containing various elements opaque to other more conventional imaging techniques. As a result, the ability to image the gaseous substances concealed within solid materials also allows non-destructive leak testing of various containers and ultimately measurement of gas partial pressures with sub-mm spatial resolution.« less

Non-contact measurement of partial gas pressure and distribution of elemental composition using energy-resolved neutron imaging

DOE PAGES

Tremsin, A. S.; Losko, A. S.; Vogel, S. C.; ...

2017-01-31

Neutron resonance absorption imaging is a non-destructive technique that can characterize the elemental composition of a sample by measuring nuclear resonances in the spectrum of a transmitted beam. Recent developments in pixelated time-of-flight imaging detectors coupled with pulsed neutron sources pose new opportunities for energy-resolved imaging. In this paper we demonstrate non-contact measurements of the partial pressure of xenon and krypton gases encapsulated in a steel pipe while simultaneously passing the neutron beam through high-Z materials. The configuration was chosen as a proof of principle demonstration of the potential to make non-destructive measurement of gas composition in nuclear fuel rods.more » The pressure measured from neutron transmission spectra (~739 ± 98 kPa and ~751 ± 154 kPa for two Xe resonances) is in relatively good agreement with the pressure value of ~758 ± 21 kPa measured by a pressure gauge. This type of imaging has been performed previously for solids with a spatial resolution of ~ 100 μm. In the present study it is demonstrated that the high penetration capability of epithermal neutrons enables quantitative mapping of gases encapsulate within high-Z materials such as steel, tungsten, urania and others. This technique may be beneficial for the non-destructive testing of bulk composition of objects (such as spent nuclear fuel assemblies and others) containing various elements opaque to other more conventional imaging techniques. As a result, the ability to image the gaseous substances concealed within solid materials also allows non-destructive leak testing of various containers and ultimately measurement of gas partial pressures with sub-mm spatial resolution.« less

Non-contact measurement of partial gas pressure and distribution of elemental composition using energy-resolved neutron imaging

NASA Astrophysics Data System (ADS)

Tremsin, A. S.; Losko, A. S.; Vogel, S. C.; Byler, D. D.; McClellan, K. J.; Bourke, M. A. M.; Vallerga, J. V.

2017-01-01

Neutron resonance absorption imaging is a non-destructive technique that can characterize the elemental composition of a sample by measuring nuclear resonances in the spectrum of a transmitted beam. Recent developments in pixelated time-of-flight imaging detectors coupled with pulsed neutron sources pose new opportunities for energy-resolved imaging. In this paper we demonstrate non-contact measurements of the partial pressure of xenon and krypton gases encapsulated in a steel pipe while simultaneously passing the neutron beam through high-Z materials. The configuration was chosen as a proof of principle demonstration of the potential to make non-destructive measurement of gas composition in nuclear fuel rods. The pressure measured from neutron transmission spectra (˜739 ± 98 kPa and ˜751 ± 154 kPa for two Xe resonances) is in relatively good agreement with the pressure value of ˜758 ± 21 kPa measured by a pressure gauge. This type of imaging has been performed previously for solids with a spatial resolution of ˜ 100 μm. In the present study it is demonstrated that the high penetration capability of epithermal neutrons enables quantitative mapping of gases encapsulate within high-Z materials such as steel, tungsten, urania and others. This technique may be beneficial for the non-destructive testing of bulk composition of objects (such as spent nuclear fuel assemblies and others) containing various elements opaque to other more conventional imaging techniques. The ability to image the gaseous substances concealed within solid materials also allows non-destructive leak testing of various containers and ultimately measurement of gas partial pressures with sub-mm spatial resolution.

Fluid responsiveness predicted by transcutaneous partial pressure of oxygen in patients with circulatory failure: a prospective study.

PubMed

Xu, Jingyuan; Peng, Xiao; Pan, Chun; Cai, Shixia; Zhang, Xiwen; Xue, Ming; Yang, Yi; Qiu, Haibo

2017-12-01

Significant effort has been devoted to defining parameters for predicting fluid responsiveness. Our goal was to study the feasibility of predicting fluid responsiveness by transcutaneous partial pressure of oxygen (PtcO 2 ) in the critically ill patients. This was a single-center prospective study conducted in the intensive care unit of a tertiary care teaching hospital. Shock patients who presented with at least one clinical sign of inadequate tissue perfusion, defined as systolic blood pressure <90 mmHg or a decrease >40 mmHg in previously hypertensive patients or the need for vasopressive drugs; urine output <0.5 ml/kg/h for 2 h; tachycardia; lactate >4 mmol/l, for less than 24 h in the absence of a contraindication for fluids were eligible to participate in the study. PtcO 2 was continuously recorded before and during a passive leg raising (PLR) test, and then before and after a 250 ml rapid saline infusion in 10 min. Fluid responsiveness is defined as a change in the stroke volume ≥10% after 250 ml of volume infusion. Thirty-four patients were included, and 14 responded to volume expansion. In the responders, the mean arterial pressure, central venous pressure, cardiac output, stroke volume and PtcO 2 increased significantly, while the heart rate decreased significantly by both PLR and volume expansion. Changes in the stroke volume induced either by PLR or volume expansion were significantly greater in responders than in non-responders. The correlation between the changes in PtcO 2 and stroke volume induced by volume expansion was significant. Volume expansion induced an increase in the PtcO 2 of 14% and PLR induced an increase in PtcO 2 of 13% predicted fluid responsiveness. This study suggested the changes in PtcO 2 induced by volume expansion and a PLR test predicted fluid responsiveness in critically ill patients. Trial registration NCT02083757.

Pressure and partial wetting effects on superhydrophobic friction reduction in microchannel flow

NASA Astrophysics Data System (ADS)

Kim, Tae Jin; Hidrovo, Carlos

2012-11-01

Friction reduction in microchannel flows can help alleviate the inherently taxing pumping power requirements associated with the dimensions involved. One possible way of achieving friction reduction is through the introduction of surface microtexturing that can lead to a superhydrophobic Cassie-Baxter state. The Cassie-Baxter state is characterized by the presence of air pockets within the surface microtexturing believed to act as an effective "shear free" (or at least shear reduced) layer, decreasing the overall friction characteristics of the surface. Most work in this area has concentrated on optimizing the surface microtexturing geometry to maximize the friction reduction effects and overall stability of the Cassie-Baxter state. However, less attention has been paid to the effects of partially wetted conditions induced by pressure and the correlation between the liquid-gas interface location within the surface microtexturing and the microchannel flow characteristics. This is mainly attributed to the difficulty in tracking the interface shape and location within the microtexturing in the typical top-down view arrangements used in most studies. In this paper, a rectangular microchannel with regular microtexturing on the sidewalls is used to visualize and track the location of the air-water interface within the roughness elements. While visually tracking the wetting conditions in the microtextures, pressure drops versus flow rates for each microchannel are measured and analyzed in terms of the non-dimensional friction coefficient. The frictional behavior of the Poiseuille flow suggests that (1) the air-water interface more closely resembles a no-slip boundary rather than a shear-free one, (2) the friction is rather insensitive to the degree of microtexturing wetting, and (3) the fully wetted (Wenzel state) microtexturing provides lower friction than the non-wetted one (Cassie state), in corroboration with observations (1) and (2).

Chemical stabilization and high pressure synthesis of Ba-free Hg-based superconductors, (Hg,M)Sr{sub 2}Ca{sub n-1}Cu{sub n}O{sub y}(N=1{approximately}3)

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

Kishio, K.; Shimoyama, J.; Hahakura, S.

1994-12-31

A homologous series of new Hg-based HTSC compounds, (Hg,M)Sr{sub 2}Ca{sub n-1}Cu{sub n}O{sub y} with n=1 to 3, have been synthesized. The stabilization of the pure phases have been accomplished by chemical doping of third elements such as M=Cr, Mo and Re. While the Hg1201(n=1) phase was readily obtained in this way, it was necessary to simultaneously dope Y into the Ca site to stabilize the Hg1212(n=2) phase. On the other hand, single-phase Y-free Hg1212(n=2) and Hg1223(n=3) samples were synthesized only under a high pressure of 6 GPa. In sharp contrast to the Ba-containing compounds, all the samples prepared in themore » present study have been quite stable during the synthesis and no deterioration in air has been observed after the preparation.« less

Characteristic effects onto C13H12N2O3 molecule dissolved in solvents of argon plasma at atmospheric pressure

NASA Astrophysics Data System (ADS)

Tanışlı, Murat; Taşal, Erol

2017-07-01

We could easily argue that the decomposition of the chemical chain molecules is a compelling application when it comes to the atmospheric pressure plasma. In this paper, we have investigated the effect of the atmospheric pressure argon plasma on 4-((2-methoxyphenyl)diazenyl)benzene-1,3,-diol molecule (abbreviated as 4MBD) at room temperature. 4MBD molecule is one of the industrial dye molecules used widely. When considering the ecological life, this molecule is very harmful and dangerous. As such, we suggest a new decomposing method for such molecules. Atmospheric pressure plasma jet is principally treated for the breakdown of the molecule in question. Fourier transform infrared spectrometry and UV-Vis spectrophotometry tools are used to characterization of the molecules subsequent to the plasma applications to 4MBD molecule in ethanol and methanol solvents. The atmospheric-pressure plasma jet of argon (Ar) as non-equilibrium has been formed by ac-power generator with frequency—24 kHz and voltage—12 kV. Characterizations for solutions prepared with ethanol and methanol solvents of 4MBD molecule have been examined after applying ( duration 3 min) the atmospheric pressure plasma jet. The molecule is broken at 6C-7N-8N=9C stretching peak in consequence of the plasma treatment. The new plasma photo-products for ethanol and methanol solutions are produced as 6C-7N-8N=9C (strong, varying) and 12C=17O (strong, wide) stretching peaks. Also, the bathochromic drifts are discerned.

Selective Encaging of N2O in N2O-N2 Binary Gas Hydrates via Hydrate-Based Gas Separation.

PubMed

Yang, Youjeong; Shin, Donghoon; Choi, Seunghyun; Woo, Yesol; Lee, Jong-Won; Kim, Dongseon; Shin, Hee-Young; Cha, Minjun; Yoon, Ji-Ho

2017-03-21

The crystal structure and guest inclusion behaviors of nitrous oxide-nitrogen (N 2 O-N 2 ) binary gas hydrates formed from N 2 O/N 2 gas mixtures are determined through spectroscopic analysis. Powder X-ray diffraction results indicate that the crystal structure of all the N 2 O-N 2 binary gas hydrates is identified as the structure I (sI) hydrate. Raman spectra for the N 2 O-N 2 binary gas hydrate formed from N 2 O/N 2 (80/20, 60/40, 40/60 mol %) gas mixtures reveal that N 2 O molecules occupy both large and small cages of the sI hydrate. In contrast, there is a single Raman band of N 2 O molecules for the N 2 O-N 2 binary gas hydrate formed from the N 2 O/N 2 (20/80 mol %) gas mixture, indicating that N 2 O molecules are trapped in only large cages of the sI hydrate. From temperature-dependent Raman spectra and the Predictive Soave-Redlich-Kwong (PSRK) model calculation, we confirm the self-preservation of N 2 O-N 2 binary gas hydrates in the temperature range of 210-270 K. Both the experimental measurements and the PSRK model calculations demonstrate the preferential occupation of N 2 O molecules rather than N 2 molecules in the hydrate cages, leading to a possible process for separating N 2 O from gas mixtures via hydrate formation. The phase equilibrium conditions, pseudo-pressure-composition (P-x) diagram, and gas storage capacity of N 2 O-N 2 binary gas hydrates are discussed in detail.

Variations in Alveolar Partial Pressure for Carbon Dioxide and Oxygen Have Additive Not Synergistic Acute Effects on Human Pulmonary Vasoconstriction

PubMed Central

Croft, Quentin P. P.; Formenti, Federico; Talbot, Nick P.; Lunn, Daniel; Robbins, Peter A.; Dorrington, Keith L.

2013-01-01

The human pulmonary vasculature constricts in response to hypercapnia and hypoxia, with important consequences for homeostasis and adaptation. One function of these responses is to direct blood flow away from poorly-ventilated regions of the lung. In humans it is not known whether the stimuli of hypercapnia and hypoxia constrict the pulmonary blood vessels independently of each other or whether they act synergistically, such that the combination of hypercapnia and hypoxia is more effective than the sum of the responses to each stimulus on its own. We independently controlled the alveolar partial pressures of carbon dioxide (Paco 2) and oxygen (Pao 2) to examine their possible interaction on human pulmonary vasoconstriction. Nine volunteers each experienced sixteen possible combinations of four levels of Paco 2 (+6, +1, −4 and −9 mmHg, relative to baseline) with four levels of Pao 2 (175, 100, 75 and 50 mmHg). During each of these sixteen protocols Doppler echocardiography was used to evaluate cardiac output and systolic tricuspid pressure gradient, an index of pulmonary vasoconstriction. The degree of constriction varied linearly with both Paco 2 and the calculated haemoglobin oxygen desaturation (1-So 2). Mixed effects modelling delivered coefficients defining the interdependence of cardiac output, systolic tricuspid pressure gradient, ventilation, Paco 2 and So 2. No interaction was observed in the effects on pulmonary vasoconstriction of carbon dioxide and oxygen (p>0.64). Direct effects of the alveolar gases on systolic tricuspid pressure gradient greatly exceeded indirect effects arising from concurrent changes in cardiac output. PMID:23935847

Variations in alveolar partial pressure for carbon dioxide and oxygen have additive not synergistic acute effects on human pulmonary vasoconstriction.

PubMed

Croft, Quentin P P; Formenti, Federico; Talbot, Nick P; Lunn, Daniel; Robbins, Peter A; Dorrington, Keith L

2013-01-01

The human pulmonary vasculature constricts in response to hypercapnia and hypoxia, with important consequences for homeostasis and adaptation. One function of these responses is to direct blood flow away from poorly-ventilated regions of the lung. In humans it is not known whether the stimuli of hypercapnia and hypoxia constrict the pulmonary blood vessels independently of each other or whether they act synergistically, such that the combination of hypercapnia and hypoxia is more effective than the sum of the responses to each stimulus on its own. We independently controlled the alveolar partial pressures of carbon dioxide (Paco 2) and oxygen (Pao 2) to examine their possible interaction on human pulmonary vasoconstriction. Nine volunteers each experienced sixteen possible combinations of four levels of Paco 2 (+6, +1, -4 and -9 mmHg, relative to baseline) with four levels of Pao 2 (175, 100, 75 and 50 mmHg). During each of these sixteen protocols Doppler echocardiography was used to evaluate cardiac output and systolic tricuspid pressure gradient, an index of pulmonary vasoconstriction. The degree of constriction varied linearly with both Paco 2 and the calculated haemoglobin oxygen desaturation (1-So2). Mixed effects modelling delivered coefficients defining the interdependence of cardiac output, systolic tricuspid pressure gradient, ventilation, Paco 2 and So2. No interaction was observed in the effects on pulmonary vasoconstriction of carbon dioxide and oxygen (p>0.64). Direct effects of the alveolar gases on systolic tricuspid pressure gradient greatly exceeded indirect effects arising from concurrent changes in cardiac output.

Pressure-induced enhancement in the thermoelectric properties of monolayer and bilayer SnSe2.

PubMed

Zou, Daifeng; Yu, Chuanbin; Li, Yuhao; Ou, Yun; Gao, Yongyi

2018-03-01

The electronic structures of monolayer and bilayer SnSe 2 under pressure were investigated by using first-principles calculations including van der Waals interactions. For monolayer SnSe 2 , the variation of electronic structure under pressure is controlled by pressure-dependent lattice parameters. For bilayer SnSe 2 , the changes in electronic structure under pressure are dominated by intralayer and interlayer atomic interactions. The n -type thermoelectric properties of monolayer and bilayer SnSe 2 under pressure were calculated on the basis of the semi-classical Boltzmann transport theory. It was found that the electrical conductivity of monolayer and bilayer SnSe 2 can be enhanced under pressure, and such dependence can be attributed to the pressure-induced changes of the Se-Sn antibonding states in conduction band. Finally, the doping dependence of power factors of n -type monolayer and bilayer SnSe 2 at three different pressures were estimated, and the results unveiled that thermoelectric performance of n -type monolayer and bilayer SnSe 2 can be improved by applying external pressure. This study benefits to understand the nature of the transport properties for monolayer and bilayer SnSe 2 under pressure, and it offers valuable insight for designing high-performance thermoelectric few-layered SnSe 2 through strain engineering induced by external pressure.