Oxygen-nitrogen Gas Mixtures Research Articles

On the applicability of the theory of ideal adsorption solutions to equilibria in the N2-O2-zeolite NaX system

Experimental data on the joint adsorption of a nitrogen-oxygen gas mixture on zeolite NaX were analyzed using the theory of ideal adsorption solutions. Acceptable accuracy was obtained in calculations of binary isotherms from the adsorption isotherms of the pure gas mixture components. The calculated binary isotherms can be used to determine the parameters of the mathematical models of binary adsorption, for instance, competitive adsorption models.

Comparison of coplanar and surface barrier discharges operated in oxygen–nitrogen gas mixtures

The characteristics of the surface barrier discharge (SBD) and the coplanar barrier discharge (CBD) operated in nitrogen–oxygen gas mixtures are investigated. The measurements of the electrode current and voltage are performed for an excitation frequency of typically 3 kHz and a discharge voltage of typically 3 and 10 kV for SBD and CBD, respectively. For all oxygen percentages over 15%, the partial discharges (PD) carry much more charge for SBD than for CBD. For pure nitrogen the PD is longer and carries more charge for CBD than for SBD.

Spatial distribution of surface treatment efficiency in coplanar barrier discharge operated with oxygen–nitrogen gas mixtures

The influence of the gas mixture of oxygen and nitrogen on the treatment efficiency distribution is investigated. The treatment efficiency is evaluated by contact angle measurement on polypropylene (PP) samples placed in varying distance from the coplanar barrier discharge electrode module. A planar electrode operated with 4 kHz signal and power of typically 10–21 W is used for treatment. A strong variation of contact angle as a function of distance from the CDB electrode surface is observed for samples treated 4 s in nitrogen discharge. Contact angle changes within 0.3 mm from 37.9 to 62.5° and it reaches 94.1° for 1.5-mm distance. It is already very close to the value of 103° measured on untreated PP. Much smaller treatment depth is obtained for mixture of nitrogen and oxygen. The experiments are performed without gas flow.

Ion contribution to the astrophysical important 388.86, 471.32 and 501.56 nm He I spectral lines broadening

Characteristics of the astrophysical important Stark broadened 388.86 nm, 471.32 nm and 501.56 nm He I spectral line profiles have been measured at electron densities between 4.4·10 22 and 8.2·10 22 m −3 and electron temperatures between 18,000 and 33,000 K in plasmas created in five various discharge conditions using a linear, low-pressure, pulsed arc as an optically thin and reproductive plasma source operated in a helium–nitrogen–oxygen gas mixture. On the basis of the observed asymmetry of the line profiles, we have obtained their ion broadening parameters ( A) caused by influence of the ion microfield and also the influence of the ion dynamic effect ( D) to the line shape. Our A and D parameters represent the first data obtained experimentally by the use of the line profile deconvolution procedure. We have found stronger influence of the ion contribution to these He I line profiles than the semiclassical theoretical approximation provides. This can be important for some astrophysical plasma modelling or for diagnostics.

Heliox improves ventilation during high-frequency oscillatory ventilation in pediatric patients.

OBJECTIVE: To describe improved ventilation during high-frequency oscillatory ventilation when a nitrogen-oxygen gas mixture is replaced by a helium-oxygen gas mixture. DESIGN: Case series. SETTING: A tertiary pediatric intensive care unit. PATIENTS: Five patients with hypoxemic respiratory failure who developed persistent respiratory acidosis during treatment with high-frequency oscillatory ventilation. INTERVENTIONS: Introduction of helium-oxygen into a conventional high-frequency oscillatory ventilation circuit. MEASUREMENTS AND MAIN RESULTS: Blood gas values (pH, Pco2, and Po2) were compared in these patients during treatment with high-frequency oscillatory ventilation with nitrogen-oxygen gas flow and then for several hours after a change in treatment to helium-oxygen gas flow. An initial 24% decrease in Pco2 was documented, and an ultimate 43% decrease in Pco2 was observed. The mechanism for this improved ventilation may be related to improved gas flow properties as well as increased CO2 diffusion resulting from helium's low-mass density. Oxygenation was not adversely affected in any way. CONCLUSION: In patients with hypoxemic respiratory failure and in whom respiratory acidosis develops during high-frequency oscillatory ventilation, the use of helium-oxygen rather than nitrogen-oxygen may improve ventilation and decrease ventilator-related trauma. Further investigation is needed to validate these findings and to elucidate the mechanisms of improved ventilation.

Heliox improves pulmonary mechanics in a pediatric porcine model of induced severe bronchospasm and independent lung mechanical ventilation.

BACKGROUND: A helium-oxygen gas mixture (heliox) has low gas density and low turbulence and resistance through narrowed airways. The effects of heliox on pulmonary mechanics following severe methacholine-induced bronchospasm were investigated and compared to those of a nitrogen-oxygen gas mixture (nitrox) in an innovative pediatric porcine, independent lung, mechanical ventilation model. RESULTS: All of the lungs showed evidence of severe bronchospasm after methacholine challenge. Prospective definition of 'heliox response' was a 15% or greater improvement in lung function in the lung receiving heliox compared with the matched lung receiving nitrox. Seven out of 10 pigs responded to heliox therapy with respect to resistance and eight out of 10 pigs responded to heliox therapy with respect to compliance and tidal volume (P < 0.03). After crossover from nitrox to heliox, eight out of eight lungs significantly improved with respect to tidal volume, resistance and compliance (P < 0.001). After crossover from heliox to nitrox all eight lungs showed a significant increase in resistance and a significant decrease in tidal volume (P < 0.001). CONCLUSIONS: In a pediatric porcine model of acute, severe methacholine-induced bronchospasm and independent lung mechanical ventilation, administration of heliox improves pulmonary mechanics, gas flow, and ventilation. Administration of heliox should be considered for support of pediatric patients with acute, severe bronchospasm requiring mechanical ventilation through small artificial airways.

Low Temperature CEMS of Corrosion Products by Sulfuric Acid Water

Conversion electron Mossbauer spectroscopy (CEMS) was used to study the corrosion products by sulfuric acid water. The acid water was put on the iron foil and evaporated under the atmosphere of several oxygen ratios in nitrogen-oxygen gas mixture in order to investigate the influence of oxygen contents on the corrosion products. The hyperfine fields of the observed sextets at 15 K suggest that the corrosion products consist of α-FeOOH, γ-FeOOH and γ-Fe2O3. The amount of γ-FeOOH becomes larger as the oxygen concentration increases. It is also found that the amount of γ-Fe2O3 becomes the largest at 1.4 % of the oxygen concentration.

Myoglobin oxygen dissociation by multiwavelength spectroscopy.

Multiwavelength optical spectroscopy was used to determine the oxygen-binding characteristics for equine myoglobin. Oxygen-binding relationships as a function of oxygen tension were determined for temperatures of 10, 25, 35, 37, and 40 degrees C, at pH 7.0. In addition, dissociation curves were determined at 37 degrees C for pH 6.5, 7.0, and 7.5. Equilibration was achieved with a myoglobin solution, at the desired temperature and pH, and 16 oxygen-nitrogen gas mixtures of known oxygen fraction. Correction for the inevitable presence of metmyoglobin was made by using a three-component least squares analysis and by correcting the end point oxymyoglobin spectra for the presence of metmyoglobin. The PO2 at which myoglobin is half-saturated with O2 (P50) was determined to be 2.39 Torr at pH 7.0 and 37 degrees C. The myoglobin dissociation curve was well fit by the Hill equation [saturation = PO2/(PO2 + P50)].

マグロ切り身のガス置換包装による品質保持

Changes in metmyoglobin (metMb) ratio to total Mb, viable bacterial numbers, sensory evaluation of odor, and K-value were examined for tuna fillets packaged with oxygen-nitrogen gas mixture in low gas-permeable plastic bags during 5°C storage. K-value was not affected by oxygen concentration. MetMb formation, growth of aerobic bacteria, and development of undesirable odor were inhibited by packaging containing less than 0.1% oxygen. Packaging with 4% and 9% oxygen were inferior to that with 21% oxygen (air) because of promoting metMb formation. Packaging with 70% oxygen was effective to keep the fresh red color of dorsal meat with low fat content for short time storage less than 3 days.

Switching effect at a platinum electrode on stabilized zirconia during oxygen reduction in the presence of NO

A galvanic cell based upon the use of stabilized zirconia as solid oxygen ion conductor has been used to measure cathodic reduction currents at a porous platinum electrode in both nitrogen-oxygen gas mixtures with and without small amounts of NO (up to 5450 ppm).

The rate of gas-soluble growth in tissue under decompression. Mathematical modelling

A mathematical model simulating the formation of gas bubbles in biological tissues under decompression is presented. It is written as a system of partial differential equations solved on a computer. For the nitrogen-oxygen gas mixture, used for respiration in deep-water immersions, the effects of the physico-chemical properties of the gases, the magnitude of pressure differentials and the density of bubble- formation centres on the bubble size and rate growth were studied. It is shown that in the case of drastic pressure differentials the formation of bubbles capable producing microcirculatory disturbances is accomplished within a few seconds.

Effect of changes in systemic oxygen tension on middle ear gas exchange.

The effect of alterations in the systemic oxygen tension on middle ear (ME) gas exchange was studied in three juvenile rhesus monkeys (Macaca mulatta) using five different inspired oxygen concentrations ranging from 15% to 100%. The anesthetized animals were ventilated for 4 hours, breathing the set of predetermined, constant oxygen-nitrogen gas mixtures. During this period, arterial and venous oxygen and carbon dioxide partial pressures were measured at 30-minute intervals; total ME gas pressure was determined indirectly using tympanometry at 10-minute intervals. Systemic oxygen blood gas tension showed predictable changes which were dependent on the fraction of inspired oxygen. However, fluctuations in the total ME gas pressure were insignificant. Findings suggested that increased systemic oxygen partial pressure does not influence ME gas exchange.

Combustion of a carbon surface in a stagnation point flow field

In the present paper the combustion behavior of a carbon surface exposed to the stagnation flow of a moist oxygen-nitrogen gas mixture is investigated theoretically. Calculations have been performed for finite homogeneous reaction rates as well as for the two limiting cases of a frozen and of an infinitely fast homogeneous reaction. For various velocity gradients, oxygen mass fractions, and humidities of the ambient flow, the theoretically determined dependence of the combustion rate upon the surface temperature is compared with the experimental combustion rate data of Matsui et al. It is shown by these comparisons that the Boudouard reaction C + CO 2 = 2CO must be relatively slow. In this case the rate of combustion is strongly influenced by the homogeneous reaction rate in the extended surface temperature range from about 1200 to 2000K. In this regime the decrease of the rate of combustion with increasing humidity, which has been observed experimentally by Matsui et al., is confirmed by the numerical results. This decrease is due to the acceleration of the homogeneous reaction by small amounts of water vapor, and it occurs only in the case of a slow Boudouard reaction. The theoretical results concerning the effects of the velocity gradient and the ambient oxygen mass fraction on the burning rate also show good agreement with the experimental data of Matsui et al. It is shown that the interactions between chemical and transport processes, which determine the combustion rate, cannot be reproduced by simply considering the limiting cases, as has often been done in the past.

Separation factor of nitrogen-oxygen gas mixtures on carbon adsorbent

1. In equilibrium and nonequilibrium adsorption of air components on the carbon molecular sieve CMS-4A in the room-temperature range, nitrogen and oxygen are adsorbed under equal conditions almost identically. The separation of air into components under near-equilibrium conditions can give only a very slight enrichment with oxygen, up to about 30%. Because of the absence of any significant difference in the kinetics of nitrogen adsorption, the use of the short-cycle adsorption technique will not give any positive effect. 2. The application of carbon sorbents to separate air into components is attractive only if a kinetic effect is present; if there is no kinetic effect, the use of carbon adsorbents is inadvisable from the thermodynamic point of view, owing to the small difference between the differential heats of adsorption of N2 and O2 and between the integration constants. 3. For approximate engineering calculations (with an accuracy of 10–15%), we can recommend precalculation of the temperature dependence of the separation factor in equilibrium adsorption of gas or vapor mixtures under the condition of applicability of the Langmuir equation, using only the individual adsorption isotherms for each component of the mixture.

The interaction of oxygen, radiation exposure and seed water content on γ-irradiated barley seeds

The roles of oxygen concentration, seed water content, and their interaction in the γ-ray-induced damage to dry barley seeds were investigated. Himalaya (C.I. 620) barley seeds were adjusted to water contents ranging from 2 to 10%, irradiated with 60Co γ-rays, and soaked at 0°C in distilled water bubbled with oxygen-nitrogen gas mixtures containing 0.0, 3.1, 6.25, 12.5, 25, 50 and 100% oxygen. Biological effects of the treatments were recorded as M 1 seedling injury. Essentially no oxygen enhancement of biological damage was obtained with an oxygen concentration of 3.1% in the gas phase of the soaking solution. The minimum OCHG needed to cause an oxygen enhancement of biological damage (3.1% OCHG) increased with increasing seed water content between 1.8 and 10.0%, and decreased as the radiation dose increased, suggesting a triple factor interaction. For moderate levels of injury (between 20 and 60%), a nearly linear increase in seedling injury was obtained when the OCHG was increased in an exponential fashion. For greater seedling injury, the response tended toward a sigmoid shaped curve, probably due to limitations of the biological parameter. The same types of response were obtained when the results were analyzed in terms of oxygen enhancement ratios (OER) obtained from seedling injury data. Decreases in oxygen-independent radiosensitivity, determined by the increase in radiation exposure required to induce 40% injury with anaerobic soakings, were obtained as the seed water content was increased from 2.0 to 9.9%. The same pattern of radiosensitivity was observed with aerobic soakings and was more pronounced at intermediate levels of OCHG. The change in radiosensitivity of seeds between seed water contents of 2.0 and 7.7% was consistent with published EPR data. The increase in response at intermediate OCHG was in part a reflection of the influence of seed water content on the level of OCHG needed to produce an oxygen enhancement of damage. Cooling seeds of 6.1% water content to dry ice temperatures immediately after irradiation at 0°C decreased both oxygen-dependent and oxygen-independent damage. The decreases in damage were greater at 20 krad than at 10 krad and tended to be greater at the higher OCHG.

Oxidation of tantalum in oxygen-nitrogen and oxygen-inert gas mixtures

The oxidation of tantalum in oxygen-nitrogen and oxygen-inert gas mixtures at925°C has been studied. The oxygen pressure was close to 0.5 atm in all experiments, and partial pressures of the second component of from 0 to 180 Torr were employed. Spherical specimens were used to provide quantitatively significant kinetic data. A model has been proposed which suggests that the oxygen pressure at the reaction interface close to the metal surface is lower than the external pressure because of the finite permeability of the porous outer oxide layer, and that the inert gas effectively reduces the permeability. The model gives good quantitative agreement with the experimental results.

Preparation of oxygen samples for [formula omitted] measurements by a combined gas chromatography-burning technique

Oxygen is quantitatively separated from oxygen-nitrogen gas mixtures by gaschromatography and adsorbed at a molecular sieve at liquid nitrogen temperature. After the desorption of oxygen from the molecular sieve the liberated oxygen can be converted to carbon dioxide. This is achieved by heating a graphite disk through focusing the radiation of a halogen lamp onto its surface.

Quenching of vibrationally excited nitric oxide by molecular oxygen and nitrogen

Vibrationally excited NO‡(X 2Π, v≳0) was produced by energetic electrons impacting on nitrogen–oxygen gas mixtures. The time decay of the NO‡ fundamental vibration–rotation bands in the presence of varying concentrations of N2 and O2 was measured. The quenching rate constants of NO(v=1) by N2 and O2 were determined to be kO2=2.4±1.5×10−14 and kN2=1.7±0.7×10−16 cm3 sec−1, respectively. Two quenching models are considered, independent and proportional to the vibrational level of the excited NO‡(v). If quenching of NO‡ by O2 is independent of v, the quoted rate constant kO2 becomes 75% larger. Computer intensity calculations of NO‡(Δv=1) are compared to radiometric intensity measurements. Intensity calculations using the uncertainty limits of the experimentally measured kO2 support the reliability of determined rate constants.

Effects of increased ambient pressure and nitrogen on man's monosynaptic reflexes.

Neurological signs during dives may result from altered excitability of central neurons. The present study assesses the effect of an increase in pressure from 1 to 3 ATA on the excitability of muscle spindles and alpha motoneurons by comparing the EMG amplitudes of the mechanically and electrically elicited monosynaptic reflexes of the gastrocnemius-soleus muscle in 10 normal adults breathing a normoxic oxygen-nitrogen gas mixture. At the surface the amplitude of the electrically elicited H response was matched to that of the mechanically elicited Achilles tendon reflex (ATR), but at depth these amplitudes became significantly different. In every subject the amplitude of the ATR, which depends upon the excitability of both muscle spindles and the alpha motoneurons, was reduced on an average of 38% (with a range of 12-75%). The H response bypasses the muscle spindles and hence, depends primarily upon alpha motoneuron excitability. Its amplitude was unaltered in four, reduced in three, and increased in three subjects. Since the ATR was always depressed despite the direction of change in the H response, we have concluded that an increase in ambient pressure (i.e., pressure per se, or nitrogen, or both) must have decreased the responsiveness of muscle spindles to the tendon tap via a reduction in fusimotor activity.

Factors affecting the precision and accuracy of Po 2, measurements using the clark electrode

The results of a laboratory quality control survey for Po 2 estimation are given. The scheme was based on the interchange between laboratories of blood specimens arriving for routine analysis, of partially equilibrated blood samples, and of oxygen-nitrogen gas mixtures. The analytical results of these samples were used to detect and quantitate errors in the measurement of Po 2. A major cause of both systematic and random errors in the Po 2 results was found to be the technique of sampling standards for calibration of the electrode. Different methods for calibrating the oxygen electrode were compared by analysing standard oxygen-nitrogen gas mixtures. The results showed that atmospheric air is a reliable standard, and that oxygen-nitrogen gas mixtures provide a convenient and accurate means of assessing the precision and accuracy of routine Po 2 measurements.