scholarly journals Nitrogen Assimilation and Transport by Ex Planta Nitrogen-Fixing Bradyrhizobium diazoefficiens Bacteroids Is Modulated by Oxygen, Bacteroid Density and l-Malate

2020 ◽  
Vol 21 (20) ◽  
pp. 7542
Author(s):  
James K. Waters ◽  
Thomas P. Mawhinney ◽  
David W. Emerich
Keyword(s):  
Amino Acid ◽  
Partial Pressure ◽  
Chemical Nature ◽  
Glutamate Uptake ◽  
Ammonium Uptake ◽  
Acid Excretion ◽  
Partial Pressure Of Oxygen ◽  
Partial Pressures ◽  
Branch Chain Amino ◽  
Rate Limiting

Symbiotic nitrogen fixation requires the transfer of fixed organic nitrogen compounds from the symbiotic bacteria to a host plant, yet the chemical nature of the compounds is in question. Bradyrhizobium diazoefficiens bacteroids were isolated anaerobically from soybean nodules and assayed at varying densities, varying partial pressures of oxygen, and varying levels of l-malate. Ammonium was released at low bacteroid densities and high partial pressures of oxygen, but was apparently taken up at high bacteroid densities and low partial pressures of oxygen in the presence of l-malate; these later conditions were optimal for amino acid excretion. The ratio of partial pressure of oxygen/bacteroid density of apparent ammonium uptake and of alanine excretion displayed an inverse relationship. Ammonium uptake, alanine and branch chain amino acid release were all dependent on the concentration of l-malate displaying similar K0.5 values of 0.5 mM demonstrating concerted regulation. The hyperbolic kinetics of ammonium uptake and amino acid excretion suggests transport via a membrane carrier and also suggested that transport was rate limiting. Glutamate uptake displayed exponential kinetics implying transport via a channel. The chemical nature of the compounds released were dependent upon bacteroid density, partial pressure of oxygen and concentration of l-malate demonstrating an integrated metabolism.

Influence of partial pressure of oxygen on thermochromic performance of VO2 thin films by RF magnetron sputtering

2019 ◽  
Vol 33 (28) ◽  
pp. 1950349 ◽  
Author(s):  
Pengfei Guo ◽  
Caijuan Liu ◽  
Junhui Liu ◽  
Ruoping Li ◽  
Mingju Huang
Keyword(s):  
Magnetron Sputtering ◽  
Partial Pressure ◽  
Rf Magnetron Sputtering ◽  
Solar Modulation ◽  
Partial Pressure Of Oxygen ◽  
Smart Windows ◽  
Glass Substrates ◽  
Partial Pressures ◽  
Phase Surface ◽  
Vo2 Thin Films

In order to obtain a material with high solar modulation ability [Formula: see text] and crystalline quality, [Formula: see text] films were prepared on quartz glass substrates using RF magnetron sputtering under various oxygen partial pressures. Their phase, surface, transmittance, and film sheet resistance properties were analyzed. As the oxygen partial pressure increased, the luminous transmittance [Formula: see text] of the film increased to as high as 55.6%, while the [Formula: see text] first increased to a maximum of 10.8% and then decreased. This paper is a meaningful aid in the application of [Formula: see text] films to smart windows.

RESPIRATION OF FISHES WITH SPECIAL EMPHASIS ON STANDARD OXYGEN CONSUMPTION: IV. INFLUENCE OF CARBON DIOXIDE AND OXYGEN

1964 ◽  
Vol 42 (5) ◽  
pp. 847-856 ◽  
Author(s):  
F. W. H. Beamish
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Consumption ◽  
Partial Pressure ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Partial Pressure Of Oxygen ◽  
Partial Pressures ◽  
Rate Of Oxygen Consumption ◽  
Standard Rate ◽  
Different Levels

Oxygen consumption was determined in relation to spontaneous activity and standard metabolism estimated by extrapolating the values to zero activity, Standard oxygen consumption was determined in relation to different partial pressures of carbon dioxide and oxygen for brook trout. Salvelinus fontinalis (Mitchill), at 10 °C, and carp, Cyprinus carpio Linnaeus, at 25 °C. In general, at each partial pressure of oxygen applied, standard oxygen consumption did not change significantly over the range of partial pressures of carbon dioxide followed. The relation for brook trout operated on a level characteristic of the partial pressure of oxygen. Although the effect of different levels of oxygen was not established for carp at 25 °C, it is presumed that the relation operated also in that species in a similar way.Acclimation to the different levels of carbon dioxide and oxygen to be tested was examined and, ordinarily, found not to change significantly the standard rate of oxygen consumption.

Isolation and characterization of n-butane-utilizing microorganisms

1972 ◽  
Vol 18 (8) ◽  
pp. 1191-1195 ◽  
Author(s):  
A. G. McLee ◽  
Agnes C. Kormendy ◽  
M. Wayman
Keyword(s):  
Partial Pressure ◽  
Growth Rates ◽  
Bacterial Isolates ◽  
Partial Pressure Of Oxygen ◽  
Bacterial Strains ◽  
Isolation And Characterization ◽  
Partial Pressures ◽  
High Partial Pressure

Fifteen bacterial strains and four molds capable of growth on n-butane were isolated and partially classified. The bacteria were mostly Arthrobacter sp. and Brevibacterium sp.; among the molds, Penicillium nigricans, Allescheria boydii, and Graphium cumeiferum were identified, while the remaining mold had the appearance of Gliocladium, but was not firmly identified. Although able to grow on other alkanes and orthodox media, the bacterial isolates could not use methane. Growth rates on n-butane were unaffected by varying air or substrate partial pressures in the range of 10–90% atmosphere. High partial pressure of oxygen was inhibitory to most bacterial isolates, the degree of inhibition varying widely, however. Growth rates on n-butanol and on glucose were significantly higher than those on n-butane. Among the molds, only the Graphium would grow well in submerged, shaking culture.

The Catalytic Decomposition of Isopropyl Alcohol Vapor on Manganese (II) Oxide

1971 ◽  
Vol 49 (23) ◽  
pp. 3778-3784 ◽  
Author(s):  
D. G. Klissurski ◽  
E. F. McCaffrey ◽  
R. A. Ross
Keyword(s):  
Partial Pressure ◽  
Isopropyl Alcohol ◽  
Catalytic Decomposition ◽  
Nitrogen Adsorption ◽  
Mesityl Oxide ◽  
Alcohol Vapor ◽  
Rate Limiting Step ◽  
Partial Pressures ◽  
Dehydration Reactions ◽  
Rate Limiting

The vapor phase decomposition of isopropyl alcohol has been studied from 210 to 365 °C on manganese(II) oxide. Rates of conversion to acetone and propylene were measured with partial pressures of isopropyl alcohol from 0.3 to 22 mm. The catalyst selectivity towards dehydrogenation was around 0.80 between 320 and 365 °C while at 306 °C it was somewhat less and depended on the alcohol partial pressure. Propylene and hydrogen additions had no effect on the reaction rate while the reaction order with respect to isopropyl alcohol partial pressure was 0.4 to 0.6 except at 306 °C when it decreased with increase in the alcohol partial pressure. The effects of acetone and water additions were shown respectively to be exerted mainly on the dehydrogenation and dehydration reactions while at acetone pressures above 4 mm, considerable amounts of by-products including mesityl oxide and heavier ketones were clearly detected. The apparent activation energy of the overall decomposition as calculated from the experimental rates was 26 ± 0.5 kcal mol−1. The results have been interpreted to be in general agreement with the concept that the rate-limiting step is linked to the direct interactions on the catalyst surface and it has been established that the reaction is significantly more complex than previously recognized. The physical properties of the manganese(II) oxide were determined by X-ray and nitrogen adsorption techniques while infrared, n.m.r., and gas chromatographic methods were used to analyze the products of catalysis.

scholarly journals Oxygen Poisoning in Drosophila

1967 ◽  
Vol 50 (6) ◽  
pp. 1693-1707 ◽  
Author(s):  
Wallace O. Fenn ◽  
Marcia Henning ◽  
Mary Philpott
Keyword(s):  
Partial Pressure ◽  
Survival Time ◽  
Empirical Equation ◽  
Continuous Exposure ◽  
Partial Pressure Of Oxygen ◽  
Time Curve ◽  
Partial Pressures ◽  
Pressure Time ◽  
Average Oxygen Concentration ◽  
Oxygen Poisoning

Fruit flies live longer at the partial pressure of oxygen found in air than at either larger or smaller partial pressures. Flies exposed to 1 atm of oxygen for 8 hr every day do not recover completely in the remaining 16 hr. In general, intermittent exposures to 1 atm of oxygen are better tolerated than continuous exposure to the same average oxygen concentration per day, but exposures to higher pressures of 2–5 atm of oxygen for as little as a half hour every two days markedly shorten the life-span. Older flies consume more oxygen per minute and are more sensitive to oxygen poisoning than young flies, and the rate of dying in 6 atm of O2, or the reciprocal of the survival time, is a linear function of the age. The oxygen pressure-time curve can be well expressed by the general empirical equation (POO2)2 x time = 120 where P is in atmosphere and survival time in hours. The progress of oxygen poisoning appears to be linear with time rather than exponential.

Effects of hyperoxia on transtracheal chloramphenicol influx

1981 ◽  
Vol 50 (2) ◽  
pp. 234-238
Author(s):  
M. M. Cloutier ◽  
E. R. Block
Keyword(s):  
Light Microscopy ◽  
Partial Pressure ◽  
Separate Group ◽  
Partial Pressure Of Oxygen ◽  
In Vitro Perfusion ◽  
Normal Morphology ◽  
Partial Pressures ◽  
Rat Trachea

Effects of exposure to high partial pressures of oxygen on transtracheal influx of chloramphenicol (Chlor) were examined using in vitro perfusion of the rat trachea. Net Chlor influx decreased with increasing duration of exposure to 100% O2 from control levels of 37.0 +/- 2.4 ng.min-1.trachea-1 to 30.0 +/- 1.0 ng.min-1.trachea-1 after 36 h of exposure to 100% O2 and was further depressed after 48 h of exposure to 100% O2 60 23.0 +/- 0.9 ng.min-1.trachea-1. Examination of the O2-exposed tracheas by light microscopy showed normal morphology. In contrast, net Chlor influx was not affected by exposure to 50% O2 for 48 h. In a separate group of rats recovery from the effects of hyperoxia was studied. Within 24 h after removal from the hyperoxic environment, net Chlor influx had returned to control levels. We conclude that high partial pressures of oxygen inhibit net Chlor influx in the rat trachea at a time when tracheal histology is normal. This inhibition is a function of the partial pressure of oxygen and the duration of exposure and it is reversible after removal from the hyperoxic environment.

Amino Acid Excretion in Patients With Gastro Intestinal Disease During Ingestion of Various Protein Supplements

1950 ◽  
Vol 16 (4) ◽  
pp. 757-763 ◽  
Author(s):  
A. Leonard Sheffner ◽  
Joseph B. Kirsner ◽  
Walter L. Palmer
Keyword(s):  
Amino Acid ◽  
Intestinal Disease ◽  
Acid Excretion ◽  
Protein Supplements

Interaction of H2O, O2 and H2 with Proton Conducting Oxides Based on Lanthanum Scandates

2019 ◽  
pp. 88-100
Author(s):  
A. S. Farlenkov ◽  
N. A. Zhuravlev ◽  
Т. A. Denisova ◽  
М. V. Ananyev
Keyword(s):  
Water Vapor ◽  
Partial Pressure ◽  
Gas Phase ◽  
Molecular Hydrogen ◽  
Proton Magnetic Resonance ◽  
Partial Pressure Of Oxygen ◽  
Proton Conducting ◽  
Conducting Oxides ◽  
Temperature Range ◽  
Apparent Level

The research uses the method of high-temperature thermogravimetric analysis to study the processes of interaction of the gas phase in the temperature range 300–950 °C in the partial pressure ranges of oxygen 8.1–50.7 kPa, water 6.1–24.3 kPa and hydrogen 4.1 kPa with La1–xSrxScO3–α oxides (x = 0; 0.04; 0.09). In the case of an increase in the partial pressure of water vapor at a constant partial pressure of oxygen (or hydrogen) in the gas phase, the apparent level of saturation of protons is shown to increase. An increase in the apparent level of saturation of protons of the sample also occurs with an increase in the partial pressure of oxygen at a constant partial pressure of water vapor in the gas phase. The paper discusses the causes of the observed processes. The research uses the hydrogen isotope exchange method with the equilibration of the isotope composition of the gas phase to study the incorporation of hydrogen into the structure of proton-conducting oxides based on strontium-doped lanthanum scandates. The concentrations of protons and deuterons were determined in the temperature range of 300–800 °C and a hydrogen pressure of 0.2 kPa for La0.91Sr0.09ScO3–α oxide. The paper discusses the role of oxygen vacancies in the process of incorporation of protons and deuterons from the atmosphere of molecular hydrogen into the structure of the proton conducting oxides La1–xSrxScO3–α (x = 0; 0.04; 0.09). The proton magnetic resonance method was used to study the local structure in the temperature range 23–110 °C at a rotation speed of 10 kHz (MAS) for La0.96Sr0.04ScO3–α oxide after thermogravimetric measurements in an atmosphere containing water vapor, and after exposures in molecular hydrogen atmosphere. The existence of proton defects incorporated into the volume of the investigated proton oxide from both the atmosphere containing water and the atmosphere containing molecular hydrogen is unambiguously shown. The paper considers the effect of the contributions of the volume and surface of La0.96Sr0.04ScO3–α oxide on the shape of the proton magnetic resonance spectra.

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