Showing papers on "Oxygen published in 1969"
TL;DR: 2,3-Diphosphoglycerate is present in the red cells of many species at about equimolar concentration to haemoglobin and facilitates oxygen unloading because it is preferentially bound to deoxyhaemoglobin in the ratio of one mole per tetramer.
Abstract: 2,3-Diphosphoglycerate is present in the red cells of many species at about equimolar concentration to haemoglobin. It lowers the oxygen affinity and thus facilitates oxygen unloading because it is preferentially bound to deoxyhaemoglobin in the ratio of one mole per tetramer.
452 citations
TL;DR: The results help to explain how the lung maintains oxygen and carbon dioxide transfer in the face of ventilation-perfusion ratio inequality and may be useful in characterizing the degree of ventilation and perfusion inequality in real situations.
290 citations
TL;DR: The experimental results support the conclusion that 0.25 mole of the oxygen in oxymyoglobin is used for the oxidation and 0.75 mole is released, which differs significantly from earlier reports of oxygen consumption during the oxidation.
220 citations
TL;DR: It is concluded that the species observed is the superoxide ion, O(2) (-), and that the stability of this ion is greatly increased in alkaline solution.
Abstract: 1. An electron-spin-resonance signal with g( parallel)2.08 and g( perpendicular)2.00 is observed by the rapid-freezing technique during the oxidation of substrates by molecular oxygen catalysed by xanthine oxidase at pH10. 2. The intensity of this signal is shown to depend on oxygen rather than on enzyme concentration, indicating that it is due to an oxygen free radical and not to the enzyme. 3. The same species is shown to be produced in the reaction at pH10 between hydrogen peroxide and periodate ions. Studies with this system have facilitated comparison of the properties of the oxygen radical with data in the literature on the products of pulse radiolysis of oxygenated water over a wide pH range. 4. It is concluded that the species observed is the superoxide ion, O(2) (-), and that the stability of this ion is greatly increased in alkaline solution. A mechanism explaining the alkaline stability is proposed. 5. The importance of O(2) (-) in the enzymic reaction is discussed.
220 citations
TL;DR: A lower range of phosphate concentrations (2, 4, 6, and 8 mM) was studied for maintenance of 2,3-DPG and ATP during storage under blood banking conditions and the lowest concentration, 2 mM, which corresponds to CPD was found to be the best concentration for maintaining 2, 3- DPG and thus hemoglobin function.
Abstract: Serial oxygen dissociation curves were performed on blood units preserved in acid-citrate-dextrose (ACD), ACD-adenine, and ACD-adenine-inosine. Dividing blood from a single donor into two or more bags allowed direct comparison between preservatives. During the 1st wk of storage in ACD, a progressive increase in oxygen affinity was observed. Thereafter, little further change was noted. Oxygen affinity increased even more rapidly during initial storage in ACD-adenine. However, with the inclusion of inosine as a preservative, oxygen affinity remained unaltered during the first 2 wk. Increases in oxygen affinity correlated well with falling levels of red cell 2,3-diphosphoglycerate (2,3-DPG) during storage. No significant changes in glutathione, reduced form (GSH), or A3 (A(I)) hemoglobin levels were noted during the first 3 wk of storage. No significant accumulation of ferrihemoglobin was detected. When blood stored 20 days in ACD or ACD-adenine was incubated with inosine for 60 min at 37 degrees C, 2,3-DPG and adenosine triphosphate (ATP) were resynthesized, and oxygen affinity was decreased. The distribution of 2,3-DPG in fresh and stored red cells appeared to influence experimental values for Hill's n, a measure of heme-heme interaction.
203 citations
TL;DR: In this paper, single particles of pure crystalline boron were injected into streams of hot oxidizing gases, generated by a gas-burner, at atmospheric pressure, and the panicle combustion process was described.
Abstract: Single particles of pure crystalline boron were injected into streams of hot oxidizing gases, generated by a gas-burner, at atmospheric pressure. Two powder samples, having average diameters of 34.5 and 44.2 μ respectively, were studied. Gas temperatures were varied from 1800 to 2900 °K, mole fractions of oxygen from 0.08 to 0.37, and mole fractions of water from 0 to 0.21. Qualitative photographic and spectroscopic observations of the panicle combustion process are described. Ignition temperatures of boron particles, 1850 to 2000 °K, were found to be independent of particle size and of gas temperature, but affected by the composition of ambient gases. Burning times, ranging from 10 to 40 msec, were found to be inversely proportional to the mole fraction of oxygen in the gas, to decrease slightly with increasing gas temperature, and to decrease substantially with addition of water vapor. Experimentally determined burning rates are correlated with diffusion rates of gaseous oxidants to the surface...
196 citations
TL;DR: In this article, self-diffusion coefficients in hyperstoichiometric uranium dioxide UO2 + x (0.005 ) were determined in the temperature range 1275-1650 °C by means of the alpha spectrum degradation method.
156 citations
TL;DR: In this article, the electrical conductivity of single crystal lithium niobate (LiNbO3) was determined as a function of temperature for various oxygen partial pressures, which can be explained by a defect equilibrium involving singly ionized oxygen vacancies and electrons.
149 citations
TL;DR: Of three systems, bulb tissue, plant leaf tissue and intact green algal cells, only the former shows an increase in rate of formation of unsaturated fatty acids with decrease in temperature, which is attributed to photosynthetic production of excess of oxygen.
Abstract: 1. Of three systems, bulb tissue, plant leaf tissue and intact green algal (Chlorella vulgaris) cells, only the former shows an increase in rate of formation of unsaturated fatty acids with decrease in temperature. 2. In bulb tissue the oxygen concentration is rate-limiting for synthesis of unsaturated fatty acids at temperatures down to 10°. 3. At elevated oxygen concentrations the formation of unsaturated fatty acids in bulb tissue increases with temperature. 4. The failure of photosynthetic tissues to respond to either lower temperatures or increased oxygen concentrations in the presence of light is attributed to photosynthetic production of excess of oxygen. This is supported by the fact that in the dark a potentiating oxygen effect on the formation of unsaturated fatty acids can be demonstrated. 5. The HCO3− ion concentration has a small effect on the formation of unsaturated fatty acids. 6. Elevated content of unsaturated acids at lower temperatures in plants is attributed to increases in oxygen concentration in solution.
146 citations
TL;DR: The presence of oxygen during the exposure of mammalian and bacterial cells to X-rays does not affect the efficiency of single strand breakage of DNA, but in bacteria it interferes with strand rejoining processes which occur during irradiation.
Abstract: The presence of oxygen during the exposure of mammalian and bacterial cells to X-rays does not affect the efficiency of single strand breakage of DNA, but in bacteria it interferes with strand rejoining processes which occur during irradiation.
132 citations
TL;DR: It is shown that the affinity of a hemoglobin solution for oxygen may be decreased by its interaction with organic phosphates, both 2,3-diph...
Abstract: Recently, Benesch et al.1 , 2 and Chanutin and Curnish3 demonstrated that the affinity of a hemoglobin solution for oxygen may be decreased by its interaction with organic phosphates. Both 2,3-diphosphoglycerate (2,3-DPG) and adenosine triphosphate (ATP) combine reversibly with deoxyhemoglobin, shifting the oxygen dissociation curve to the right. The role of 2,3-DPG in regulating the oxygen dissociation curve may be quantitatively the more important since its concentration in erythrocytes is approximately four times that of ATP. Under in vitro conditions in which the level of deoxyhemoglobin is raised the level of 2,3-DPG also promptly increases.4 , 5 This finding suggested that the increase in . . .
Journal Article•
TL;DR: A quantitative explanation of why small retinal vessels constrict severely and retinal blood flow drops to less than half the value on air is contained based on published figures for the arteriovenous oxygen difference and blood flow in the retinal and choroidal circulations.
Abstract: During oxygen breathing small retinal vessels constrict severely and retinal blood flow drops to less than half the value on air. This paper contains a quantitative explanation of why this occurs based on published figures for the arteriovenous oxygen difference and blood flow in the retinal and choroidal circulations. The choroid has a high blood flow and a low arteriovenous oxygen difference. Once the arterial oxygen tension, paOt, rises to about 270 mm. Hg, the intake of the oxygen extraction from the choroidal blood can be met from dissolved oxygen. When pa0t rises above this level the oxygen tension in the choroidal tissue and venous blood rises in step xoith it because the capacity of reduced hemoglobin to buffer changes in oxygen pressure is lost. At a paO- of 400 mm. Hg, 97 per cent of the retina between the choriocapillaris and the deep retinal capillaries is supplied with oxygen from the choroid compared with 60 per cent on air. At higher values of pa0s there is a delivery of oxygen from the choroid to the deep retinal capillaries and under hyperbaric oxygen almost the whole thickness of retina could be supplied with oxygen from the choroid alone.
TL;DR: In this article, carbon and oxygen self-diffusion coefficients were determined by exchange between calcite grains and a large reservior of C14-labeled CO2 at 250°-750°C.
Abstract: Carbon self-diffusion coefficients were determined by exchange between calcite grains and a large reservior of C14-labeled CO2 at 250°–750°C. The progress of diffusion and the surface area of the grains were measured by the C14 uptake of the solid. Both carbon and oxygen self-diffusion coefficients were determined by exchange between calcite grains and a limited reservoir of C13- and O18-enriched CO2 at 650°–850°C. The progress of diffusion was measured by the change in isotope composition of the gas. On an Arrhenius plot of log D versus 103/T°K, the carbon self-diffusion coefficients are fitted to two straight lines. Carbon diffusivity determined by both methods in unannealed and annealed material at temperatures above 550°C are given by D = 1.3 × 103 exp(−88,000/RT)cm2/sec. Oxygen self-diffusion coefficients were higher than the corresponding carbon values by up to a factor of 4. Carbon diffusivity determined by the C14 method in unannealed calcite below 550°C are given by D = 4.6 × 10−16 exp(−17,000/RT)cm2/sec. Diffusivity in annealed material is lower by a factor of 50. The relative rates of oxygen and carbon self-diffusion indicate that there may be several mechanisms of oxygen migration in calcite in the high temperature region. A detailed examination of the C14 uptake results suggest that carbon self-diffusion is depth-dependent for the shallow penetration distances obtained in these experiments. Extrapolation of these results suggests that solid-state diffusion will not significantly alter the isotopic record of calcite under a wide range of geologic environments.
01 Jan 1969
TL;DR: In this article, the magnetic susceptibility of the 1:2 adduct of oxygen with Co salen obtained by the solid-state reaction has been measured from room temperature to 90°K: it was concluded that, when allowance is made for small impurities of unconverted Cosalen, this product is substantially diamagnetic.
Abstract: Some 1:2 adducts of oxygen with NN′-ethylenebis(salicylideneiminato)cobalt(II), Co salen, and its ring-substituted analogues are reported. These compounds, which were obtained from solutions of the cobalt(II)–Schiff's base complexes, were found to be substantially diamagnetic from room temperature to 90°K. The magnetic susceptibility of the 1:2 adduct of oxygen with Co salen obtained by the solid-state reaction has been measured from room temperature to 90°K: it is concluded that, when allowance is made for small impurities of unconverted Co salen, this product is substantially diamagnetic. Finally, conditions have been found in which Co 3-methoxysalen gives a 1:1 adduct with oxygen in pyridine as solvent. I.r. and magnetic susceptibility data suggest that the oxygen group in this adduct of formula Co 3-methoxysalen,py,O2 is symmetrically bonded to cobalt in an ethylene-like type of arrangement.
TL;DR: In this article, a microprobe electrode was used to determine dissolved oxygen concentrations near the surface and within a bacterial slime mass supplied with a continuous flow of nutrient solution, indicating substrate-limited respiration.
Abstract: A microprobe electrode was used to determine dissolved oxygen concentrations near the surface and within a bacterial slime mass supplied with a continuous flow of nutrient solution. With dilute medium, the oxygen profile became level at high concentrations within the film, indicating substrate-limited respiration. More concentrated medium caused the profile to fall to low oxygen concentrations characteristic of oxygen-limited respiration. Oxygen responses to sudden changes in concentration of nutrient medium were measured. Estimates of microbial respiration rate and of diffusivity of oxygen were based on well-known diffusion equations.
TL;DR: In this article, the authors used stabilized zirconia tubes as a solid electrolyte to remove oxygen from stationary or streaming gas, where the minimum pressures (activities) that can be accurately measured are limited by the onset of electronic conduction in the electrolyte.
Abstract: Electrolytic cells based on stabilized zirconia as a solid electrolyte may be used to remove oxygen from stationary or streaming gas. The minimum pressures (activities) that can be accurately measured are limited by the onset of electronic conduction in the electrolyte. In buffered gases, the lowest pressure that can be attained either by the capacity of the buffer or by the decomposition kinetics of the buffer molecules. Typical values of the oxygen pressures that can be reached when using commercial high‐density sintered stabilized zirconia tubes as an electrolyte, are , , and .
TL;DR: In this paper, a large number of silicon samples containing oxygen and carbon impurities after various doses of irradiation at room temperature by 2 MeV electrons have been measured in the range 1-25 μm for a number of different silicon samples.
TL;DR: The affinity of blood for oxygen is dependent on temperature, which would seem to present a disadvantage to those fishes which encounter large seasonal temperature changes, considering the well-known acclimatory abilities of many fishes, it would seem reasonable to propose the occurrence of seasonal modification of blood oxygen equilibria to compensate for changes in temperature.
TL;DR: Mass spectrometric studies of ionic species formed in negative corona discharges in air and pure oxygen have been carried out at total pressures ranging from 5 Torr to 760 Torr, demonstrating the importance of trace amount of carbon dioxide.
Abstract: Mass spectrometric studies of ionic species formed in negative corona discharges in air and pure oxygen have been carried out at total pressures ranging from 5 Torr to 760 Torr. In air, the importance of trace amount of carbon dioxide is demonstrated by the dominant presence CO(3)(-) ion at pressures above 50 Torr. This ion comprises over 90% of the total ionic species which reach the anode at atmospheric pressure. At relative humidities of 20-50%, the contributions of the hydrated species such as CO(3)(-)(H(2)O), O(-)(H(2)O), and O(3)(-)(H(2)O)) are less than 10%. In pure oxygen the two important ionic species appear to be O(3)(-) and O(-) with the contribution of the former increasing with pressure. Trace impurities of carbon dioxide in oxygen, however, convert the carriers to CO(3)(-) which makes the dominant contribution to the total current.
01 Jan 1969
TL;DR: In this article, the presence of steam has been found to accelerate the oxidation in oxygen of mild steel and two grades of pure iron of varying purity, and the effect was found to be greater on round test pieces than on flat rectangular ones.
Patent•
08 Jul 1969
TL;DR: In this paper, an approach for measuring oxygen concentration based on oxygen quenching of molecular luminescence was proposed, which was evaluated by comparison with an oxygen-shielded reference member in the same environment.
Abstract: Apparatus for measuring oxygen concentration based on oxygen quenching of molecular luminescence; the quenching is evaluated by comparison with an oxygen-shielded reference member in the same environment, using respective photosensitive detectors responding to fluorescence from an unshielded fluorescing member and the reference member.
TL;DR: Post-treatment performance on psychological tests of cognitive functioning showed highly significant gains over pretreatment levels in experimental subjects, suggesting an improved performance that persisted beyond the temporary increase in arterial oxygen tension levels.
Abstract: Thirteen elderly male patients with measured cognitive deficits were treated with 30 intermittent exposures to 100 per cent oxygen at 2.5 atmospheres absolute. Five controls, each exposed at the same time and manner as a paired experimental patient, breathed a low oxygen mixture that maintained essentially normal alveolar oxygen tension despite increased ambient pressure. Arterial samples for blood gas determinations were obtained from each patient during one of the early hyperbaric exposures. Analysis showed the expected large intra-exposure increase in arterial oxygen tension among the experimental subjects. Negligible changes in arterial oxygen tension were found among control patients. Post-treatment performance on psychological tests of cognitive functioning showed highly significant gains over pretreatment levels in experimental subjects, suggesting an improved performance that persisted beyond the temporary increase in arterial oxygen tension levels. Control patients showed no improvement ...
TL;DR: In this article, the rates of oxidation of electrode graphite and coconut charcoal granules in carbon dioxide (with or without dilution with inert gases) were measured over a pressure range of 10−3 to 40 atm at temperatures from 700 to 1300°C.
TL;DR: The decreased oxygen affinity found in blood of patients with low levels of cardiac output is considered as a compensatory adjustment to poor tissue blood flow, promoting the diffusion of oxygen from blood in tissue capillaries to intracellular sites of utilizaton.
Abstract: Oxygen affinity of blood was measured in 16 patients (nonsmokers) without anemia and with clinical evidence of low cardiac output. Of these patients, 12 were catheterized and showed an arteriovenous oxygen concentration difference across the lungs greater than 5 ml/100 ml. The partial pressure of oxygen required to half-saturate their blood with oxygen (P50) averaged 29.4 mm Hg (SD ± 1.9). Blood from normal subjects (nonsmokers) had an average P50 of 27.3 mm Hg (SD ± 0.9). The decreased oxygen affinity found in blood of patients with low levels of cardiac output is considered as a compensatory adjustment to poor tissue blood flow, promoting the diffusion of oxygen from blood in tissue capillaries to intracellular sites of utilizaton.
TL;DR: In this article, the authors compared the electron emission density for LaB6 cathodes with that for other common cathode types and found that poisoning is related to the gas pressure, cathode temperature and heat of adsorption.
Abstract: Electron‐emission density for LaB6 cathodes is compared with that for other common cathode types. Equations for describing the poisoning mechanism are presented. Poisoning is related to the gas pressure, cathode temperature, and heat of adsorption. Posioning was measured with a flowing gas system which maintained a constant pressure in the vicinity of the cathode for varying adsorption rates. Poisoning rates were determined by the cathode temperature and gas pressure. An equilibrium poisoned emission level was reached within a few minutes for each cathode temperature and gas pressure. Poisoning gases used were oxygen, carbon dioxide, air, hydrogen, nitrogen, and argon. Oxygen was the most active poisoning gas and argon the least active. No poisoning results until a critical pressure is reached; the emission then decays rapidly with increasing pressure. Resistance to poisoning increases with increasing cathode temperature. At a cathode temperature of 1570°C, the critical poisoning pressure for oxygen is ab...