Characterization of Hydrogen Photoevolution in Oscillatoria chalybea Detected by Means of Mass Spectrometry

1997 ◽  
Vol 52 (11-12) ◽  
pp. 775-781 ◽  
Author(s):  
Refat Abdel-Basset ◽  
Klaus P. Bader
Keyword(s):  
Gas Exchange ◽  
Partial Pressure ◽  
Hydrogen Evolution ◽  
Dark Adaptation ◽  
Molecular Hydrogen ◽  
Chlorophyll Concentration ◽  
Continuous Light ◽  
Direct Determination ◽  
Hydrogen Gas ◽  
Oscillatoria Chalybea

Abstract The filamentous non-heterocystous cyanobacterium Oscillatoria chalybea is capable to photoevolve molecular hydrogen when the cells are flushed to anaerobiosis with nitrogen or argon and exposed to short light flashes or continuous light. The light-induced hydrogen gas exchange of Oscillatoria chalybea has been investigated by direct determination of dynamic changes in the hydrogen partial pressure at m/e=2 in the H/D collector of a mass spectrometric set-up. By means of this technique also the time curves of the light-induced hydrogen gas exchange could be directly recorded. Depending on the chlorophyll concentration in the measuring cell we observed an increasing hydrogen content of the aqueous Oscillatoria suspension i.e. a dark evolution of molecular hydrogen. Upon the onset of light an initial rise of the H 2-signal was observed which was increasingly mixed or followed by a hydrogen uptake. The capability to photoevolve molecular hydrogen was maximal with young cultures and decreased with increasing age. The hydrogen evolution signals require relatively short dark adaptation to get pronounced; few seconds suffice for 2/3 of the hydrogen evolution amplitude. Prolonged dark adaptation maximizes the flash amplitudes. The hydrogen evolu­tion signals do not deactivate by low flash frequency Oscillatoria chalybea evolves molecular hydrogen following growth on nitrogen free or nitrate containing medium. Increase of the oxygen partial pressure of the assays completely abolishes the hydrogen evolution signals with an I50-value of 6 μm.

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.

scholarly journals Second-generation laryngeal mask airway as an alternative to endotracheal tube during prolonged laparoscopic abdominal surgery: a comparative analysis of intraoperative gas exchanges

2021 ◽  
Author(s):  
S Park ◽  
JE Lee ◽  
GS Choi ◽  
JM Kim ◽  
JS Ko ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Laryngeal Mask Airway ◽  
Abdominal Surgery ◽  
Partial Pressure ◽  
Endotracheal Tube ◽  
Second Generation ◽  
Laryngeal Mask ◽  
Arterial Partial Pressure ◽  
Prolonged Surgery

Introduction: Despite several advantages over endotracheal tube (ETT), laryngeal mask airway (LMA), which is used in emergencies under difficult airway maintenance conditions, is rarely utilized in prolonged surgery. We compared the variables representing intraoperative gas exchange with second-generation LMA and ETT during prolonged laparoscopic abdominal surgery. Methods: Prolonged surgery was defined as a surgery lasting more than 2 h. In total, 394 patients who underwent laparoscopic liver resection via either second-generation LMA or ETT were retrospectively analysed. Parameters including end-tidal pressure of carbon dioxide (ETCO2), tidal volume (TV), respiratory rate (RR), peak inspiratory pressure (PIP), arterial partial pressure of carbon dioxide (PaCO2), pH, and ratio of arterial partial pressure of oxygen to fractional inspired oxygen (PFR) during surgery were compared between the two groups. In addition, the incidence of postoperative pulmonary complications (PPC) including pulmonary aspiration was also compared. Results: The values of ETCO2, TV, RR and PIP during pneumoperitoneum were comparable between the two groups. Although PaCO2 at 2 h after induction was higher in patients with LMA (40.5 vs. 38.5 mmHg, p < 0.001), the pH and PFR values of the two groups were comparable. The incidence of PPC was not different. Conclusion: During prolonged laparoscopic abdominal surgery, the second-generation LMA facilitates adequate intraoperative gas exchange and represents an alternative to ETT.

Gas-Exchange Rates in a Small Lake as Determined by the Radon Method

1973 ◽  
Vol 30 (10) ◽  
pp. 1475-1484 ◽  
Author(s):  
Steve Emerson ◽  
Wallace Broecker ◽  
D. W. Schindler
Keyword(s):  
Exchange Rate ◽  
Gas Exchange ◽  
Exchange Rates ◽  
Partial Pressure ◽  
Lake Water ◽  
Radon Concentration ◽  
Natural Waters ◽  
Carbon Dioxide Partial Pressure ◽  
Nitrogen And Phosphorus ◽  
Gas Exchange Rate

The radon method, used previously in ocean-atmosphere systems, is used here to determine the gas-exchange rate between the atmosphere and lake 227 of the Experimental Lakes Area. Fertilization of the lake with nitrogen and phosphorus caused the carbon dioxide partial pressure in the lake water to drop well below atmospheric levels; hence, in order to better understand the carbon budget of the lake, an estimate of the CO2 gas-exchange rate was necessary.To determine gas-exchange rates by measuring radon evasion to the atmosphere the source of radon in the lake water must be dissolved radium. Since the radon concentration in lakes derives not only from the decay of dissolved radium but also from the inflow of radon-rich groundwaters, radium was added to the lake to increase the radon concentration well above this fluctuating background level. Although this procedure was complicated by algal uptake of the radium in the lake (Emerson and Hesslein 1973), we were able to place limits on the gas-exchange rate.Our results indicate that the "stagnant boundary layer" thickness is approximately 300 μ. This value is among the largest observed in natural waters. Using this value and the partial pressure of CO2 in the lake water we have calculated an invasion rate of 17 ± 8 mmoles CO2/m2 day.

scholarly journals Growth and Photosynthetic Response of Two Persimmon Rootstocks (Diospyros kaki and D. virginiana) under Different Salinity Levels

2014 ◽  
Vol 42 (2) ◽  
pp. 386-391 ◽  
Author(s):  
Meral INCESU ◽  
Berken CIMEN ◽  
Turgut YESILOGLU ◽  
Bilge YILMAZ
Keyword(s):  
Gas Exchange ◽  
Leaf Gas Exchange ◽  
Chlorophyll Concentration ◽  
Dry Mass ◽  
Diospyros Kaki ◽  
Gas Exchange Parameters ◽  
Leaf Chlorophyll ◽  
Salinity Levels ◽  
Leaf Chlorophyll Concentration ◽  
Exchange Parameters

Salinity continues to be a major factor in reduced crop productivity and profit in many arid and semiarid regions. Seedlings of Diospyros kaki Thunb. and D. virginiana L. are commonly used as rootstock in persimmon cultivation. In this study we have evaluated the effects of different salinity levels on photosynthetic capacity and plant development of D. kaki and D. virginiana. Salinity was provided by adding 50 mM, 75 mM and 100 mM NaCl to nutrient solution. In order to determine the effects of different salinity levels on plant growth, leaf number, plant height, shoot and root dry mass were recorded. Besides leaf Na, Cl, K and Ca concentrations were determined. Also leaf chlorophyll concentration, chlorophyll fluorescence (Fv’/Fm’) and leaf gas exchange parameters including leaf net photosynthetic rate (PN), stomatal conductance (gS), leaf transpiration rate (E), and CO2 substomatal concentration (Ci) were investigated. Significant decrease of leaf number, shoot length and plant dry mass by increasing salinity levels was observed in both rootstocks. D. virginiana was less affected in terms of plant growth under salinity stress. Leaf chlorophyll concentration reduction was higher in the leaves of D. kaki in comparison to D. virginiana in 100 mM NaCl treatment. By increasing salinity levels PN, gS and E markedly decreased in both rootstocks and D. kaki was more affected from salinity in terms of leaf gas exchange parameters. In addition there was no significant difference but slight decreases were recorded in leaf chlorophyll fluorescences of both rootstocks.

Preliminary evaluation of a predictive controller for a rotary blood pump based on pulmonary oxygen gas exchange

2019 ◽  
Vol 233 (2) ◽  
pp. 267-278 ◽  
Author(s):  
Feng Huang ◽  
Zhe Gou ◽  
Yang Fu
Keyword(s):  
Gas Exchange ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Left Ventricular ◽  
Blood Pump ◽  
Rotary Blood Pump ◽  
Blood Pumps ◽  
Control Objective ◽  
Predictive Controller ◽  
Rotary Blood Pumps

Physiological control of rotary blood pumps is becoming increasingly necessary for clinical use. In this study, the mean oxygen partial pressure in the upper airway was first quantitatively evaluated as a control objective for a rotary blood pump. A model-free predictive controller was designed based on this control objective. Then, the quantitative evaluation of the controller was implemented with a rotary blood pump model on a complete cardiovascular model incorporated with airway mechanics and gas exchange models. The results show that the controller maintained a mean oxygen partial pressure at a normal and constant level of 138 mmHg in the left heart failure condition and restored basic haemodynamics of blood circulation. A left ventricular contractility recovery condition was also replicated to assess the response of the controller, and a stable result was obtained. This study indicates the potential use of the oxygen partial pressure index during pulmonary gas exchange when developing a multi-objective physiological controller for rotary blood pumps.

Hydrogenase Enzyme like Nanocatalysts FeS2 and FeSe2 for Molecular Hydrogen Evolution Reaction

2019 ◽  
Vol 248 ◽  
pp. 39-42 ◽  
Author(s):  
R. Shwetharani ◽  
D.H. Nagaraju ◽  
R. Geetha Balakrishna ◽  
V. Suvina
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Molecular Hydrogen ◽  
Hydrogenase Enzyme

scholarly journals Endothelin receptor antagonist improves donor lung function in an ex vivo perfusion system

2020 ◽  
Vol 27 (1) ◽  
Author(s):  
K. Walweel ◽  
K. Skeggs ◽  
A. C. Boon ◽  
L. E. See Hoe ◽  
M. Bouquet ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Partial Pressure ◽  
Ex Vivo ◽  
Weight Ratio ◽  
Dry Weight ◽  
Lung Damage ◽  
Endothelin Receptor ◽  
Donor Pool ◽  
Ex Vivo Lung Perfusion ◽  
Tissue Samples

Abstract Background A lung transplant is the last resort treatment for many patients with advanced lung disease. The majority of donated lungs come from donors following brain death (BD). The endothelin axis is upregulated in the blood and lung of the donor after BD resulting in systemic inflammation, lung damage and poor lung graft outcomes in the recipient. Tezosentan (endothelin receptor blocker) improves the pulmonary haemodynamic profile; however, it induces adverse effects on other organs at high doses. Application of ex vivo lung perfusion (EVLP) allows the development of organ-specific hormone resuscitation, to maximise and optimise the donor pool. Therefore, we investigate whether the combination of EVLP and tezosentan administration could improve the quality of donor lungs in a clinically relevant 6-h ovine model of brain stem death (BSD). Methods After 6 h of BSD, lungs obtained from 12 sheep were divided into two groups, control and tezosentan-treated group, and cannulated for EVLP. The lungs were monitored for 6 h and lung perfusate and tissue samples were processed and analysed. Blood gas variables were measured in perfusate samples as well as total proteins and pro-inflammatory biomarkers, IL-6 and IL-8. Lung tissues were collected at the end of EVLP experiments for histology analysis and wet-dry weight ratio (a measure of oedema). Results Our results showed a significant improvement in gas exchange [elevated partial pressure of oxygen (P = 0.02) and reduced partial pressure of carbon dioxide (P = 0.03)] in tezosentan-treated lungs compared to controls. However, the lungs hematoxylin–eosin staining histology results showed minimum lung injuries and there was no difference between both control and tezosentan-treated lungs. Similarly, IL-6 and IL-8 levels in lung perfusate showed no difference between control and tezosentan-treated lungs throughout the EVLP. Histological and tissue analysis showed a non-significant reduction in wet/dry weight ratio in tezosentan-treated lung tissues (P = 0.09) when compared to control. Conclusions These data indicate that administration of tezosentan could improve pulmonary gas exchange during EVLP.

The behaviour of plants in various gas mixtures

1971 ◽  
Vol 179 (1056) ◽  
pp. 177-188
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Partial Pressure ◽  
Higher Plants ◽  
Dry Mass ◽  
Carbon Dioxide Partial Pressure ◽  
Ambient Oxygen ◽  
Leaf Dry Mass ◽  
Rate Of Photosynthesis ◽  
Effect Of Oxygen

The effects of the composition and pressure of the ambient gas mixture on the diffusive gas exchange of leaves, and the effects of carbon dioxide and oxygen on respiration and photosynthesis are described. When photosynthesis is limited by the rate at which carbon dioxide reaches the chloroplasts, the net rate of photosynthesis of many (but not all) plant species depends on the ambient oxygen partial pressure. The effect of oxygen may be principally to stimulate a respiratory process rather than to inhibit carboxylation. However, when photosynthesis is not limited by the carbon dioxide supply, this respiratory process seems to be suppressed. The gas exchange of plant communities responds to the aerial environment in the way expected from measurements on single leaves, but the growth response to a given difference in gas composition is smaller than expected because of adaptation, notably in the ratio of leaf dry mass to leaf area. It is concluded that the growth rate of higher plants in given illumination will be independent of the partial pressure of oxygen and of other gases likely to be used to dilute it, provided that the carbon dioxide partial pressure is so adjusted (probably to not more than 2 mbar (200 Pa)) that the rate of photosynthesis is not limited by the rate of diffusion to the chloroplasts.

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