Journal articles on the topic 'O2 gas mixture'
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1
Efremov, Alexandr M., and Kwang-Ho Kwon. "PLASMA PARAMETERS AND COMPOSITION IN CF4/O2/Ar GAS MIXTURE." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 60, no. 1 (March 1, 2017): 50. http://dx.doi.org/10.6060/tcct.2017601.5518.
Abstract:
For citation:Efremov A.M., Kwon K.-H. Plasma parameters and composition in CF4/O2/Ar gas mixture. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 1. P. 50-55.The effects of O2/Ar mixing ratio in CF4/O2/Ar mixture on both plasma parameters and fluxes of active species determining the dry etching kinetics in this gas system were analyzed. The investigation combined plasma diagnostics by Langmuir probes and zero-dimensional plasma modeling. It was found that the substitution of Ar with O2 at constant fraction of CF4 in a feed gas does not result in the non-monotonic change in F atom density, as it was repeatedly reported for the binary CF4/O2 gas mixtures. The mechanisms of this phenomenon as well as its possible impact on the etching/polymerization kinetics were discussed in details.
2
Zhang, Boya, Yuyang Yao, Mai Hao, Xingwen Li, Jiayu Xiong, and Anthony B. Murphy. "Study of the dielectric breakdown strength of CO2–O2 mixtures by considering ion kinetics in a spatial–temporal growth avalanche model." Journal of Applied Physics 132, no. 9 (September 7, 2022): 093302. http://dx.doi.org/10.1063/5.0093568.
Abstract:
The gas mixture CO2–O2 has been considered as an insulation and arc-quenching medium in gas-insulated switchgears. In this paper, the dielectric breakdown properties of CO2–O2 mixtures at different O2 concentrations and gas pressures were studied theoretically by considering ion kinetics in a spatial–temporal growth avalanche model. A kinetic scheme that includes all the main reactions likely to occur in CO2–O2 mixtures is presented. An improved method to calculate the dielectric strength of the gas mixture is developed, based on an avalanche model that considers both spatial growth and temporal processes. Next, the reaction rates of ionization, attachment, detachment and ion conversion, the effective ionization Townsend coefficient αeff/N, and reduced critical electric field strength ( E/N) cr in CO2–O2 mixtures at different mixing ratios and gas pressures are analyzed in detail. Finally, a pulsed Townsend experiment is performed to verify the validity and accuracy of the calculation method. Based on this, one detachment reaction rate is modified to yield more accurate results. Better consistency between the results and the experimental values supports the validity of the kinetic system, reaction rates, and the improved calculation method.
3
Kirkden, RD, L. Niel, SA Stewart, and DM Weary. "Gas killing of rats: the effect of supplemental oxygen on aversion to carbon dioxide." Animal Welfare 17, no. 1 (February 2008): 79–87. http://dx.doi.org/10.1017/s0962728600032012.
Abstract:
AbstractHigh concentrations of carbon dioxide (CO2), used for killing laboratory rodents, are known to be more strongly aversive to rats than sweet food items are attractive. This study investigated whether the maintenance of a high oxygen (O2) concentration, using a gas mixture of 70% CO2 and 30% O2, would reduce aversion to CO2 during a gradual-fill procedure. Eight male Wistar rats, aged 10 months, were housed individually in an apparatus consisting of two cages, one higher than the other and joined by a tube. In a series of trials, subjects entered the lower cage for a reward of 20 sweet food items. The gas was turned on at the moment the rat started eating the reward items and flowed into the lower cage at a fixed rate. There were four treatments: 1) 100% CO2 at 14.5% cage volume min–1; 2) gas mixture at 14.5% min–1; 3) gas mixture at 21.0% min–1, which delivered CO2 at approximately 14.5% min–1 and 4) air, with each subject tested with each treatment four times. Measures of willingness to stay and eat in the lower cage (latency to stop eating, latency to leave and the number of reward items eaten) were much lower in all three gas treatments than in air, indicating that the CO2 and the CO2 + O2 mixture were both more strongly aversive than sweet food items were attractive. Comparing the gas mixture with 100% CO2, the latency to leave and the number of reward items eaten were slightly higher in the CO2 + O2 mixture at 21% min–1 than in CO2 at 14.5% min–1, indicating that the addition of O2 slightly reduced the aversiveness of CO2 in the gradual-fill procedure. This reduction is not enough to warrant recommending the use of CO2 + O2 mixtures for killing rats.
4
Tian, Shuangshuang, Xiaoping Jin, Xiaoxing Zhang, Xiaohan Li, Zian Yuan, and Li Chen. "Study on thermal decomposition characteristics of C6F12O/O2/CO2 gas mixtures." AIP Advances 12, no. 11 (November 1, 2022): 115003. http://dx.doi.org/10.1063/5.0123968.
Abstract:
Due to its excellent insulation properties and environmental characteristics, C6F12O gas mixture shows a wide range of applications prospects in low and medium voltage gas insulated equipment. The thermal decomposition characteristics of gas insulating medium are of great importance for the industrial application of gases and the operation and maintenance of equipment. In this paper, the type and concentration of the main products of the thermal decomposition of C6F12O/O2/CO2 gas mixture are researched experimentally with different O2 mixing ratios, and the effective gas production rate is analyzed. The mechanism of thermal decomposition of C6F12O/O2/CO2 gas mixture is studied based on ReaxFF molecular dynamics. The experimental results show that the main thermal decomposition products are CF4, C2F6, C3F6, C3F8, C4F10, C5F12, and C6F14. The addition of O2 promotes the thermal decomposition of the C6F12O/O2/CO2 gas mixture. Theoretical studies show that the C6F12O in the mixture undergoes the multistage decomposition reaction. The main particles of all levels of decomposition are C3F7COCF2, CF3, CF3CFC(O) (CF2), CF2CO, C3F7, C3F7C(O) (CF2), CFC(O) (CF2), FCCO, F, CF3CFCF2, CO, and CF2. The results of the research can provide some reference for the engineering application and maintenance of C6F12O gas mixture insulated equipment.
5
NAKAGAWA, Yuichi, Yasuhiko YOSHIDA, Tadataka YAMASHITA, and Junji FURUKAWA. "Plasma polymerization of butadiene-O2 mixture gas." KOBUNSHI RONBUNSHU 46, no. 4 (1989): 209–13. http://dx.doi.org/10.1295/koron.46.209.
6
Kobtsev, Vitaly, Sergey Kostritsa, Dmitrii Kozlov, Alexey Pelevkin, Valery Smirnov, Natalia Titova, Sergey Torokhov, Konstantin Vereshchagin, and Sergey Volkov. "CARS and Fluorescent study of ignition of H2/O2 mixtures upon photodissociation of O2 molecular." MATEC Web of Conferences 209 (2018): 00010. http://dx.doi.org/10.1051/matecconf/201820900010.
Abstract:
The research is devoted to gas mixtures ignition by UV laser radiation. The dissociation of O2 molecules by a pulse of excimer ArF laser radiation at 193-nm wavelength with formation of the chemically active oxygen atoms initiating chain reactions which cause ignition of H2/O2 mixture was employed. The experimental test bench was created with CARS and fluorescent techniques for experimental investigation of some peculiarities of mixture ignition and combustion caused by such photo-dissociation, at conditions typical for combustion chamber. Two-dimensional numerical modeling of combustion process in model combustion chamber, based on kinetic mechanism of H2 oxidation including atom O(1P) and radicals OH(A2Σ+), was performed.
7
Talviste, Rasmus, Kalev Erme, Peeter Paris, Jüri Raud, Toomas Plank, and Indrek Jõgi. "Effective ionization coefficient in mixtures of Ar and O2 determined using the Townsend discharge." AIP Advances 12, no. 10 (October 1, 2022): 105213. http://dx.doi.org/10.1063/5.0098014.
Abstract:
Precise knowledge of the fundamental ionization properties of gases, such as the effective ionization coefficient, is crucial for discharges in mixtures of Ar:O2, which are significant for a wide range of plasma applications. This study determined the effective ionization coefficient in electronegative gas mixtures of Ar:O2 in the pressure range of 10–800 Torr and reduced electric field strength E/ N range of 40–1200 Td utilizing a steady-state non-self-sustaining Townsend discharge. The reduced effective ionization coefficient α e/ N increased with E/ N and decreased with increasing O2 content in the gas mixture. The experimental results were compared with a model which was based on calculating the ionization and attachment coefficients with BOLSIG+. The ion conversion of O− to O2−, detachment from O2−, and formation of O3 were accounted for similarly as has been done with N2:O2 mixtures. Reasonably good agreement between the measurements and the model calculations was achieved for Ar:O2 mixtures with the O2 content between 20% and 70%. A discrepancy of more than 20% between measurement and calculations was observed at low E/ N values when the O2 content was below 20% and at high E/ N values when the O2 content was above 70%. Several possible explanations were proposed for the observed discrepancy; however, more elaborate models are required. The reduced critical electric field E/ N crit, where the apparent effective ionization coefficient is zero, was determined as a function of the O2 content in the Ar:O2 mixtures. E/ N crit increased with increasing O2 content in the mixture.
8
Prokic-Cvetkovic, Radica, Andjelka Milosavljevic, Aleksandar Sedmak, and Olivera Popovic. "The influence of the oxygen equivalent in a gas-mixture on the structure and toughness of microalloyed steel weldments." Journal of the Serbian Chemical Society 71, no. 3 (2006): 313–21. http://dx.doi.org/10.2298/jsc0603313p.
Abstract:
Testing were carried out on two steels. The first was microalloyed with Nb and second with Ti, Nb and V. The impact toughness of weld metals of these steels was evaluated using an instrumented Charpy pendulum. Five different gas mixtures (Ar, CO2, O2) were used to determine the optimal gas shielded metal arc process for both steels. The oxygen equivalent was used as a representative parameter of a mixture to follow, in particularly, its effect on the microstructure, toughness and crack propagation energy of the weld metal. For these investigated steels, the optimum gas mixture was established (5%CO2, 0.91%O2, balance Ar), which provided the maximum crack propagation energy, due to the microstructure which consisted dominantly of acicular ferrite.
9
Zagidullin, M. V., and N. A. Khvatov. "Kinetics of O2(1Δ) self-quenching in the O2— O2(1Δ) — H2O gas mixture." Quantum Electronics 40, no. 9 (November 13, 2010): 800–803. http://dx.doi.org/10.1070/qe2010v040n09abeh014368.
10
Efremov, Alexander M., Dmitry B. Murin, and Sergey V. Belyaev. "ON MECHANISMS OF INCREASING HCL DISSOCIATION DEGREE IN GLOW DISCHARGE PLASMA." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 61, no. 7 (June 18, 2018): 62. http://dx.doi.org/10.6060/ivkkt.20186107.5697.
Abstract:
The influence of initial compositions of the binary HCl+Ar and HCl+O2 gas mixtures on the hydrogen chloride dissociation kinetics in low temperature gas discharge plasma was investigated. The experiments were carried out under the conditions of direct current glow discharge at constant total gas pressure (100 Pa) and discharge current (25 mA). The data on electro-physical plasma parameters and plasma composition were obtained by modeling procedure based on the simultaneous solution of Boltzmann kinetic equation and the equations of chemical kinetics for neutral and charged species in a steady-state approximation. It was found that an increase in the second component fraction in both gas mixtures results in the sufficient increase in the HCl dissociation degree (aHCl = 23–43% for 0–80% Ar and 23–90% for 0–80% O2), which is associated with different mechanisms. Particularly, in the HCl+Ar gas mixture, an effect of increasing aHCl is provided by an increase in the electron impact dissociation frequency due to the change in electro-physical plasma parameters, such as electron mean energy and electron density. For the HCl+O2 gas mixture, such mechanism is almost negligible because of the weak disturbances in both electron energy distribution and formation/decay balance for charged species in the combination of two molecular electronegative gases. At the same time, the HCl dissociation kinetics in this gas system appears to be strongly dependent on the gas-phase interactions with ground state of oxygen atoms O(3P), metastable atoms O(1D) and OH radicals. It was found that the rates of corresponding processes begin to exceed the HCl electron impact dissociation rate at 20% O2 in HCl+O2.Forcitation:Efremov A.M., Murin D.B., Belyaev S.V. On mechanisms of increasing hcl dissociation degree in glow discharge plasma. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 7. P. 61-66
11
Yamada, Y., A. Ito, K. Kuono, H. Yoshida, and Y. Kobayashi. "Laser deposition of iron in oxygen atmosphere." Proceedings in Radiochemistry 1, no. 1 (September 1, 2011): 429–33. http://dx.doi.org/10.1524/rcpr.2011.0078.
Abstract:
AbstractIron oxide films were produced by pulsed laser deposition (PLD) of 57Fe metal in an oxygen atmosphere and their compositions were studied by Mössbauer spectroscopy. The effects of gas-phase reactions were investigated by varying the pressure of O2 gas or an O2/Ar gas mixture. When PLD was performed in a high-pressure O2 atmosphere, the main product in the film was trivalent iron oxide particles. When the O2 pressure was reduced, hematite Fe2O3 became dominant in the film, while wüstite FeO was produced at very low O2 pressures. PLD in an O2/Ar gas mixture produced films of trivalent iron oxide particles and hematite solid, but wüstite was not produced. Increasing the substrate temperature during deposition induced annealing of the films, reducing the lattice defect density. X-ray diffraction patterns were obtained to confirm the assignments, and the surface morphologies of the films were investigated by scanning electron microscopy.
12
Malvin, G. M., and M. P. Hlastala. "Effects of lung volume and O2 and CO2 content on cutaneous gas exchange in frogs." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 251, no. 5 (November 1, 1986): R941—R946. http://dx.doi.org/10.1152/ajpregu.1986.251.5.r941.
Abstract:
The effects of lung O2 and CO2 content and volume on cutaneous gas exchange and perfusion were investigated in the frog, Rana pipiens. (Ha)-anesthetized frogs were equilibrated with 9.5% Freon-22 (Fr, chlorodifluoromethane) and 1.1% Ha. Cutaneous elimination of Fr, Ha, and CO2 into a small sample chamber on the abdomen was measured with a mass spectrometer. Introducing an air mixture into the lung decreased cutaneous Fr, Ha, and CO2 elimination. Lung inflation with an O2 mixture decreased cutaneous gas elimination more than with the air mixture. Inflation with a N2 mixture had no effect. The response to lung inflation with the air mixture was not affected by adding 4.8% CO2 to the air mixture or by atropine. Voluntary lung ventilation decreased CO2 and Fr elimination. The results indicate that intrapulmonary O2 is a factor regulating skin breathing. If a change in lung volume is also a factor, it requires a concomitant change in lung O2. Intrapulmonary CO2 and cholinergic nerves are not involved in cutaneous respiration across the abdomen.
13
Khan, Muhammad Ibrahim, Muhammad Aslam Khan, Muhammad Iqbal Zaman, Najeeb ur Rehman, Asad Masood, and Naqib Ullah. "Enhancement of O-atom density through collisions with Ne by laser-produced plasma in Ne–O2 gas mixtures and possible energy transfer mechanism." International Journal of Modern Physics B 33, no. 18 (July 20, 2019): 1950198. http://dx.doi.org/10.1142/s0217979219501984.
Abstract:
Laser-produced plasma in Ne and O2 gases and Ne–O2 gas mixture with different O2 fractions have been investigated. The plasma were produced by focusing a laser beam of 5 ns pulse duration from a Nd:YAG laser ([Formula: see text] = 1064 nm) through a lens of 5 cm focal length into the chamber filled with different gas species at different pressures. Possible enhancement in O-atom densities through collisions with metastable Ne atoms by the laser-created plasma in Ne–O2 gas mixtures and possible energy transfer mechanism was studied. Study of energy transfer through collisions was carried out by comparisons of the line intensities of the emitted spectra from laser-created plasma in gas mixtures and pure gases with the technique of optical emission spectroscopy (OES). Strong evidence of energy transfer from Ne to O was recorded. From the result, it was suggested that the high-lying metastable levels of Ne were responsible for enhancement of O-atoms density in gas mixture and Ne also play important role in energy transfer mechanism through collision. Also, behaviors of the line intensities under different laser energies were studied. Behaviors of line intensities and line widths were the main parameters measured. Stark broadening of lines in Ne with different laser energies was recorded. The electron temperature T[Formula: see text] and number density N[Formula: see text] were found to be 1.01 eV and 9.44 × 10[Formula: see text] cm[Formula: see text] in Ne at different laser energy/pulse with total pressure of 1000 mbar.
14
Wu, Eugene Y., Khalid W. Barazanji, and Robert L. Johnson. "Sources of error ina- aD O 2 calculated from blood stored in plastic and glass syringes." Journal of Applied Physiology 82, no. 1 (January 1, 1997): 196–202. http://dx.doi.org/10.1152/jappl.1997.82.1.196.
Abstract:
Wu, Eugene Y., Khalid W. Barazanji, and Robert L. Johnson, Jr. Sources of error in a-aDO2 calculated from blood stored in plastic and glass syringes. J. Appl. Physiol. 82(1): 196–202, 1997.—We studied the effects of time delay on blood gases, pH, and base excess in blood stored in glass and plastic syringes on ice and the effects of resulting errors on calculated alveolar-to-arterial [Formula: see text] difference (a-[Formula: see text]). Matched samples of dog whole blood were tonometered with gas mixtures of 5% CO2-12% O2-83% N2 ( mixture A), 10% CO2-5% O2-85% N2 ( mixture B), and 2.88% CO2-4% O2-93.12% N2 ( mixture C). Tonometered blood samples were transferred to 5-ml glass (5G), 5-ml plastic (5P), and 3-ml plastic (3P) syringes and stored on ice. Blood gases were measured every 1 h up to 6 h. In 5G,[Formula: see text] progressively decreased in blood tonometered with mixture A but rose in blood tonometered with mixtures B and C. O2 saturation progressively fell in all cases. In 5G, blood [Formula: see text]progressively rose regardless of which gas mixture was used, and pH as well as base excess progressively fell. The rise in[Formula: see text] was faster in plastic than in glass syringes, and O2 saturation always rose in plastic syringes. Differences between storage in plastic and glass syringes on [Formula: see text] change were greatest when initial blood [Formula: see text] was highest ( mixture A). At the highest[Formula: see text], O2 exchange was faster in 3P than in 5P. The rise of [Formula: see text] was just as fast in plastic as in glass syringes, but in both the rise in[Formula: see text] was faster at a higher initial[Formula: see text] ( mixture B) than at lower initial[Formula: see text] ( mixtures B and C). Rates of[Formula: see text] and[Formula: see text] change in matched samples were significantly faster in 3P than in 5P. Errors due to rises in[Formula: see text] and[Formula: see text] cause additive errors in calculateda-[Formula: see text], and when blood is stored in plastic syringes for >1 h significant errors result. Errors are greater in normoxic blood, in which estimateda-[Formula: see text]decreased by >10 Torr after 6 h on ice in plastic syringes, than in hypoxic blood.
15
Liu, Wei Long, Shu Huei Hsieh, and Wen Jauh Chen. "Manufacture and Characterization of TiO2 Nanowires by CVD." Advanced Materials Research 415-417 (December 2011): 697–700. http://dx.doi.org/10.4028/www.scientific.net/amr.415-417.697.
Abstract:
Under the catalysis of Co metal, the nanosized titania could be grown on Ti substrate at elevated temperature under a gas mixture of N2, O2, CH4 , and H2O. The nanosized titania was characterized by scanning electron microscope for its morphology, and by an energy dispersion spectrometer for its composition. The results showed that the straight and long titania nanowire could be formed at 900°C under a gas mixture of N2, O2, and CH4. When H2O vapor was added to the gas mixture, the titania nanowire became somewhat curved. The tiania nanowire was oxygen deficient, i.e. TiO2-X.
16
Iwata, Kazuya, Sou Suzuki, Reo Kai, and Ryoichi Kurose. "Direct numerical simulation of detonation–turbulence interaction in hydrogen/oxygen/argon mixtures with a detailed chemistry." Physics of Fluids 35, no. 4 (April 2023): 046107. http://dx.doi.org/10.1063/5.0144624.
Abstract:
Direct numerical simulation is conducted to address the detonation–turbulence interaction in a stoichiometric hydrogen/oxygen/argon mixture. The argon dilution rate is varied so that the mixture composition is 2H2 + O2 + 7Ar and 2H2 + O2 + Ar to discuss the effects of cell regularity on the sensitivity to turbulence. Turbulent Reynolds number and turbulent Mach number are taken to be common for both mixtures. The results show that the shock and flame of detonation in both mixtures are significantly deformed into corrugated ones in the turbulent flow, producing many small unburned gas pockets. However, one-dimensional time-averaged profiles reveal the different sensitivity of the mixtures: in the highly diluted mixture (2H2 + O2 + 7Ar), the reaction progress is not much influenced by turbulence, whereas in the less-diluted mixture (2H2 + O2 + Ar), the reaction takes place more rapidly with turbulence. Analysis of the properties of turbulence and turbulent fluctuations in the detonations clarifies that the direct contribution of turbulence to the flame front is weaker; there is no clear correlation between the heat release and the curvature of the flame. On the other hand, a broader Mach number distribution just upstream of the shock front creates more hot spots in the less-diluted mixture, which results in a shorter induction length. These results indicate that the main contribution of turbulence is creation of different shock strength, which could lead to different reaction rates depending on the cell regularity.
17
Pramanik, B. K., Somlal Das, K. Subrata Pr, and A. Hatta. "Effect of Rare Gas Admixture on N2 /O2 Gas Mixture Discharge." Journal of Engineering and Applied Sciences 5, no. 5 (May 1, 2010): 347–53. http://dx.doi.org/10.3923/jeasci.2010.347.353.
18
Efremov, Alexander M., Vladimir B. Betelin, and Kwang-Ho Kwon. "PLASMA PARAMETERS AND SiO2 ETCHING KINETICS IN C4F8 + Ar + O2 GAS MIXTURE." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 63, no. 6 (May 13, 2020): 37–43. http://dx.doi.org/10.6060/ivkkt.20206306.6163.
Abstract:
The effect of Ar/O2 mixing ratio on plasma parameters, steady-state densities of active species and SiO2 etching kinetics in the three-component C4F8+Ar+O2 gas mixture was studied under typical conditions of reactive ion etching process (inductive 13.56 MHz RF discharge, total gas pressure of 6 mTorr, input power of 700 W and bias power of 200 W). The investigation combined etching rate measurements, plasma diagnostics by Langmuir probes and 0-dimensional (global) plasma modeling in order to determine steady-state densities and fluxes of plasma active species. It was found that the full substitution of Ar for O2 at constant fraction of fluorocarbon gas (in fact, the transition from 50% C4F8 + 50% Ar to 50% C4F8 + 50% O2 gas system): 1) results in weakly non-monotonic (with a maximum) SiO2 etching rate with close values for both O2-free and Ar-free plasmas; 2) causes the monotonic decrease in both F atom flux and ion energy flux; and 3) suppresses the formation of the fluorocarbon polymer film on the etched surface through its oxidative destruction pathway. The model-based analysis of SiO2 etching kinetics allowed one to conclude that an increase in effective probability for SiO2 + F reaction contradicts with the behavior ion energy flux as well as demonstrate the agreement with the change in gas-phase parameters characterizing the fluorocarbon film thickness. Therefore, an increase in O2 content in a feed gas influences the effective reaction probability by decreasing fluorocarbon film thickness and providing better access of F atoms to the etched surface.
19
Hong, Jong Woo, Hyun Woo Tak, Young Hun Choi, Hee Jung Kim, Dong Woo Kim, and Geun Young Yeom. "Etch Characteristics of Low-K Materials Using CF3I/C4F8/Ar/O2 Inductively Coupled Plasmas." Science of Advanced Materials 14, no. 7 (July 1, 2022): 1258–64. http://dx.doi.org/10.1166/sam.2022.4312.
Abstract:
In this study, pulsed CF3I/C4F8/Ar/O2 inductively coupled plasmas have been studied for low-k etching, and the effects of CF3I addition to C4F8/Ar/O2 on the plasma characteristics and etch characteristics of low-k materials were investigated. The increased ratio of CF3I/(CF3I+C4F8) in the gas mixture increased CF3 radicals while decreasing CF2 radicals in the plasma, and which are related to the etching and polymerization, respectively. Therefore, the etch rates of SiCOH increased with increasing the CF3I ratio. However, the etch selectivity over an amorphous carbon layer and photoresist was the highest at the ratio of 0.5 because the CF2/F flux ratio from the plasma and the C/F ratio on the polymer layer were the highest at the CF3I ratio of 0.5. The SiCOH damage was decreased with increasing CF3I ratio and the SiCOH damage appeared to be very low, particularly when the CF3I ratio was ≥0.5 by showing low Si–CH3 bond loss, low F penetration, and a low surface roughness. Therefore, it is believed that, as opposed to the C4F8/Ar/O2 gas mixture only, mixing 50% CF3I into the C4F8/Ar/O2 gas mixtures resulted in not only a high etch selectivity over mask materials, but also a potentially reduced etch damage.
20
Chen, F. J., A. S. Menon, S. V. Lichtenstein, N. Zamel, and A. S. Slutsky. "Mechanisms of gas exchange with different gases during constant-flow ventilation." Journal of Applied Physiology 68, no. 1 (January 1, 1990): 88–93. http://dx.doi.org/10.1152/jappl.1990.68.1.88.
Abstract:
To investigate the mechanisms responsible for the difference in gas exchange during constant-flow ventilation (CFV) when using gases with different physical properties, we used mixtures of 70% N2-30% O2 (N2-O2) and 70% He-30% O2 (He-O2) as the insufflating gases in 12 dogs. All dogs but one had higher arterial PCO2 (PaCO2) with He-O2 compared with N2-O2. At a flow of 0.37 +/- 0.12 l/s, the mean PaCO2's with N2-O2 and He-O2 were 41.3 +/- 13.9 and 53.7 +/- 20.3 Torr, respectively (P less than 0.01); at a flow rate of 0.84 +/- 0.17 l/s, the mean PaCO2's were 29.1 +/- 11.3 and 35.3 +/- 13.6 Torr, respectively (P less than 0.01). The chest was then opened to alter the apposition between heart and the lungs, thereby reducing the extent of cardiogenic oscillations by 58.4 +/- 18.4%. This intervention did not significantly alter the difference in PaCO2 between N2-O2 and He-O2 from that observed in the intact animals, although the individual PaCO2 values for each gas mixture did increase. When the PaCO2 was plotted against stagnation pressure (rho V2), the difference in PaCO2 between N2-O2 and He-O2 was nearly abolished in both the closed- and open-chest animals. These findings suggest that the different PaCO2's obtained by insufflating gases with different physical properties at a fixed flow rate, catheter position, and lung volume result mainly from a difference in the properties of the jet.
21
Seol, Youbin, Hong Young Chang, Seung Kyu Ahn, and Shin Jae You. "Study on characteristics of electron parameters on inert gas addition in a capacitively coupled SF6/O2 plasma." AIP Advances 12, no. 12 (December 1, 2022): 125117. http://dx.doi.org/10.1063/5.0127857.
Abstract:
In this paper, characteristics of electron parameters of SF6/O2 and inert gas mixture in a capacitively coupled plasma were studied. Here, gases such as He, Ar, and Xe were added to SF6/O2 mixture and electron energy probability functions (EEPFs) were measured. The electron parameters were acquired, which agreed well with EEPF behaviors. Normally, the inert gas functioned as an electron source and the electron density tended to increase. When the inert gas ratio exceeded other gases, the effect of the mixture varied on each gas. He showed its unique behaviors with the increase in electron temperature. Ar and Xe showed consistent behaviors with increasing electron density and decreasing electron temperature as the inert gas proportion increases. Different behaviors of the electron parameters in inert gases can be explained by the complex contribution of electron attachment of SF6 and the ionization rate of each inert gas.
22
Doan Hoang The, Golosov D.A., Jin Zhang, Kananovich N.A., Zavadski S.N., and Melnikov S.N. "Influence of the method of gas supply to the chamber on the processes of reactive magnetron sputtering of Ti-Al composite target." Technical Physics 68, no. 3 (2023): 381. http://dx.doi.org/10.21883/tp.2023.03.55814.261-22.
Abstract:
The paper demonstrates study results of the processes of reactive magnetron sputtering of a Ti-Al composite target in an Ar/O2 gas mixture with various methods of gas supply to the chamber. It has been established that, regardless of the method of gas supply, when changing the oxygen concentration in the Ar/O2 gas mixture, the ratio of the Al and Ti content in the deposited Ti1-xAlxOy films changes. The metal content ratio in the deposited films varies in proportion to the change in the ratio of the control lines intensities of the optical emission of aluminum AlI (396.15 nm) and titanium TiI (395.82 nm) in plasma. This makes it possible to effectively use the method of optical emission spectroscopy to predict and control the content of metals in deposited films. Based on studies of the dielectric characteristics of deposited Ti1-xAlxOy films, it was discovered that with separate gas supply (Ar is supplied to the target region, O2 is supplied to the substrate region), in contrast to the joint gas supply (the Ar/O2 gas mixture is supplied to the target region), it is possible to deposit dielectric films in the transient mode at relatively high sputtering rates. In this case, the oxygen supply to the substrate region makes it possible to increase the oxygen content in the films up to 60-64%. Keywords: preactive magnetron sputtering, composite target, thin films, titanium-aluminum oxide, elemental composition, permittivity, dielectric loss tangent.
23
Xiao, Song, Shuangshuang Tian, Xiaoxing Zhang, Yann Cressault, Ju Tang, Zaitao Deng, and Yi Li. "The Influence of O2 on Decomposition Characteristics of c-C4F8/N2 Environmental Friendly Insulating Gas." Processes 6, no. 10 (September 29, 2018): 174. http://dx.doi.org/10.3390/pr6100174.
Abstract:
The c-C4F8 gas is considered to have great potential as a gaseous medium for gas-insulated equipment, due to its good insulation properties and its relatively low greenhouse gas potential (GWP) relative to SF6. However, the decomposition is an important indicator of its use in equipment. In this paper, the decomposition characteristics of c-C4F8 and the influence by oxygen have been explored through experiments and theoretical calculations. Firstly, the breakdown test of mixed gas was carried out and the precipitated elements of the electrodes and breakdown products of gas mixture were analyzed by X-ray photoelectron spectroscopy (XPS) and gas chromatography mass spectrometry (GC-MS). At the same time, the differences in decomposition products have also been studied when a small amount of O2 was present. The path and mechanism of c-C4F8 decomposition is then discussed, based on density functional theory (DFT). The results show that the black powdery substance descends on the electrode surface after the breakdown of the mixture of c-C4F8/N2 gas containing O2, and its main constituent elements are C, O and F. O2 can promote the decomposition of c-C4F8. The mixture with O2 produced a large number of additional toxic and corrosive COF2 in addition to generating more CF4, C2F4, C2F6, C3F6 and C3F8. The GWP values of the products are lower than SF6. Comprehensive insulation properties and decomposition characteristics, c-C4F8 should not be mixed with dry air for use, and the oxygen content should be strictly controlled in c-C4F8 mixed gas.
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Lim, Young Min, Bok Su Jang, and Jin Hyun Koh. "The Effect of Shielding Gas and Arc Voltage on the Bead Shape and Pore Generation of Galvanized Steel Pipe Welds with Gas Metal Arc Welding." Advanced Materials Research 746 (August 2013): 240–44. http://dx.doi.org/10.4028/www.scientific.net/amr.746.240.
Abstract:
The present study was carried out to investigate the effect of shielding gases (Ar, CO2, Ar+5%CO2, Ar+10%CO2, Ar+20%CO2, Ar+2%O2, Ar+5%O2 and Ar+10%O2) and arc voltage (16-24V) on the bead shape and porosity formation of galvanized steel pipe welds made by a gas metal arc welding process. It was confirmed that the bead height was lowered and bead width was wider with increasing voltages. Bead shapes made by Ar was narrow and convex due to a high surface tension while those made by mixture gas compositions such as Ar+CO2 and Ar+O2t became wider and smoother due to a lower surface tension. The pores were generated the least at low arc voltages of 16-20V and they were more formed over 22V. It was confirmed that Ar produced the most porosity while active and mixture gases such as CO2 and Ar+10%CO2 , Ar+5%O2 and Ar+10%O2 produced little pores by forming ZnO in the weld pool.
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Sinha, Nidhi, Mi-Young Song, Hyonu Chang, Heechol Choi, Hyun-Jae Jang, Yeon-Ho Oh, and Ki-Dong Song. "Electron Impact Cross Sections and Transport Studies of C3F6O." Applied Sciences 13, no. 23 (November 23, 2023): 12612. http://dx.doi.org/10.3390/app132312612.
Abstract:
Electron impact scattering from C3F6O is studied in this work. The R-matrix method was used for the calculations of elastic, momentum transfer, and excitation cross sections. The attachment cross section was obtained through a parametric estimator based on the R-matrix outputs. The Binary-Encounter-Bethe (BEB) method was used for computing the ionization cross section. The obtained cross section set was used for the transport studies using the BOLSIG+ code, which is a two-term Boltzmann equation solver. The present calculation was performed for steady-state Townsend experimental conditions for E/N, covering a range of 100–1000 Td. The critical dielectric strength of pure C3F6O was found to be 475 Td, which is much greater than that of SF6 (355 Td). The effect of the addition of different buffer gases, such as CO2, N2, and O2, was also examined. For the C3F6O–CO2, C3F6O–N2, and C3F6O–O2 mixtures with 65%, 55%, and 60% C3F6O, respectively, the critical dielectric strength was determined to be essentially the same as that of pure SF6. The presence of synergism was confirmed for these gas mixtures. We further derived the Paschen curve using a fitting method with the transport parameters as the basic inputs. The minimum breakdown voltage of C3F6O accounted for only 55% of that of SF6. The buffer gas mixture improved the condition; however, the performance of CO2 and O2 mixtures was not satisfactory. The addition of N2 as the buffer gas significantly improved the breakdown property of the gas. The mixture of ≥99% of N2 or ≤1% of C3F6O gave a better breakdown characteristic than SF6. Any proportion ≥90% of N2 or ≤10% of C3F6O was suitable in the higher pressure ranges. The present work demonstrates the potential of C3F6O as a substitute gas for SF6 with a negligible environmental threat.
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Lambauer, Vera, and Regina Kratzer. "Lab-Scale Cultivation of Cupriavidus necator on Explosive Gas Mixtures: Carbon Dioxide Fixation into Polyhydroxybutyrate." Bioengineering 9, no. 5 (May 10, 2022): 204. http://dx.doi.org/10.3390/bioengineering9050204.
Abstract:
Aerobic, hydrogen oxidizing bacteria are capable of efficient, non-phototrophic CO2 assimilation, using H2 as a reducing agent. The presence of explosive gas mixtures requires strict safety measures for bioreactor and process design. Here, we report a simplified, reproducible, and safe cultivation method to produce Cupriavidus necator H16 on a gram scale. Conditions for long-term strain maintenance and mineral media composition were optimized. Cultivations on the gaseous substrates H2, O2, and CO2 were accomplished in an explosion-proof bioreactor situated in a strong, grounded fume hood. Cells grew under O2 control and H2 and CO2 excess. The starting gas mixture was H2:CO2:O2 in a ratio of 85:10:2 (partial pressure of O2 0.02 atm). Dissolved oxygen was measured online and was kept below 1.6 mg/L by a stepwise increase of the O2 supply. Use of gas compositions within the explosion limits of oxyhydrogen facilitated production of 13.1 ± 0.4 g/L total biomass (gram cell dry mass) with a content of 79 ± 2% poly-(R)-3-hydroxybutyrate in a simple cultivation set-up with dissolved oxygen as the single controlled parameter. Approximately 98% of the obtained PHB was formed from CO2.
27
Malpas, S. C., A. Shweta, W. P. Anderson, and G. A. Head. "Functional response to graded increases in renal nerve activity during hypoxia in conscious rabbits." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 271, no. 6 (December 1, 1996): R1489—R1499. http://dx.doi.org/10.1152/ajpregu.1996.271.6.r1489.
Abstract:
Changes in renal sympathetic nerve activity (SNA) are postulated to influence renal function in selective ways, such that different levels of activation produce particular renal responses, initially in renin release, then sodium excretion, with changes in renal hemodynamics occurring only with much greater stimulus intensities. The aim of this study was to determine the renal hemodynamic and excretory responses to graded physiological increases in renal SNA induced by breathing different hypoxic gas mixtures. Experiments were performed in seven conscious rabbits subjected to four gas mixtures (14% O2, 10% O2, 10% O2 + 3% CO2, and 10% O2 + 5% CO2) and instrumented for recording of renal nerve activity. After a 30-min control period, rabbits were subjected to one of the four gas mixtures for 30 min, and then room air was resumed for a further 30 min. The four gas mixtures increased renal SNA by 14, 38, 49, and 165% respectively, but arterial pressure (thus renal perfusion pressure) was not altered by any of the gas mixtures. The greatest level of sympathetic activation produced significant falls in glomerular filtration rate (GFR), renal blood flow, sodium and fluid excretion, and significant increases in plasma renin activity. These returned to levels not significantly different from control conditions in the 30-min period after the gas mixture. When the changes to the various gas mixtures were analyzed within each rabbit, a significant linear relationship was found with all variables to the increase in SNA. Renal denervation in a separate group of seven rabbits completely abolished all of the above responses to the different gas mixtures. Thus graded activation of renal nerves induced by changes in inspired gas mixtures resulted in graded decreases in renal blood flow, GFR, and sodium excretion and graded increases in renin activity, with the changes occurring across a similar range of nerve activities; there was no evidence for a selective change in any renal variable.
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Mammarappallil, MD, PhD, Joseph, Richard E. Moon MD, Neil R. MacIntyre MD, W. Michael Foster PhD, Samantha J. Womack MS, Maureen D. Ainslie MS RT(R)MR, H. Page McAdams, MD, Ahmed F. Halaweish PhD, Kingshuk Choudury PhD, and H. Cecil Charles PhD. "Cardio-Respiratory tolerability of perfluoropropaneEnhanced MRI of pulmonary ventilation." Journal of Lung, Pulmonary & Respiratory Research 7, no. 4 (December 30, 2020): 107–15. http://dx.doi.org/10.15406/jlprr.2020.07.00239.
Abstract:
Rationale: Recent advances in perfluoropropane magnetic resonance imaging of the lung have provided the means to assess pulmonary ventilation and gas distribution throughout the pulmonary airways and acini in a non-invasive manner. Objectives: The increased density of the inhaled PFP/O2 gas mixture generates longer wash-in times compared to wash-out while breathing room air and leads to slight increases in airway resistance (Raw) and respiratory effort by the subject during imaging. As a consequence of these gas-related effects, we sought to evaluate the cardio-respiratory tolerability of the PFP/O2 gas mixtures in our sequential breath-hold imaging protocol in normal subjects and subjects with obstructive lung disease. Methods: Tolerability was determined by evaluation of changes in vital signs (Heart Rate, Systolic and Diastolic Blood Pressure, Respiratory Rate and Temperature (otic)) at 3 time points (screening, pre-imaging and post-imaging) Measurements and Main Results: Assessment of vital signs before and after the administration of perfluoropropane gas mixture by matched pair analysis demonstrated statistically different values for Heart rate (Mean Difference =-2.417 bpm), Systolic BP (Mean Difference=6.95 mmHg), Diastolic BP (Mean Difference=3.86 mmHg) and SpO2 (Mean Difference=0.56%) even though these do not represent physiologically significant differences compared to activities of daily living such as climbing a flight of stairs. Conclusions: Our data demonstrate no negative outcomes in using PFP gas to image pulmonary ventilation. The PFP gas mixture is safe, well tolerated, and provides a three dimensional ‘picture’ (representation) of inhaled gas distribution for subject cohorts of normal and obstructive lung disease.
29
Hu, Xuechao, and Junhui Dong. "Regeneration Mechanism of Sulfur Absorption Via Samarium-doped Cerium Adsorbents in the Gas Atmosphere of O2/N2." Materials 13, no. 5 (March 9, 2020): 1225. http://dx.doi.org/10.3390/ma13051225.
Abstract:
Sulfides existing in many high-temperature gas mixtures have a negative effect on various industrial applications. Ce-based adsorbents are becoming a hotspot in the high-temperature desulfurization process owing to their excellent thermal stability at high temperatures and regeneration capacity. In this study, we investigate the regeneration path of samarium-doped cerium (SDC) sorbent at high temperature. The SDC adsorbent showed a good sulfur removal ability and excellent regeneration capacity. Ce2O2S and Ce(SO4)2 are observed in the used adsorbent, and Ce2O2S is the main sulfur-containing species. The regeneration path of the Ce2O2S is the key to the regeneration mechanism of the adsorbent. There are two regeneration paths for the Ce2O2S at high temperature in O2/N2 gas mixture. In air stream, the Ce2O2S is oxidized to Ce2O2SO4 and then decomposes into CeO2 and SO2. In a 2% O2/N2 gas condition, the Ce2O2S directly generates CeO2 and elemental sulfur with O2 assistance.
30
Wani, Javed Ahmad, Sadia Ali Wani, and Salma Mariyam. "Intraoperative Evaluation of Effects of Different Gas Mixtures (Oxygen 100%, O2 50%:N2O 50%, Air on Cuff Pressure of PLMA (Proseal LMA)." International Journal of Research and Review 8, no. 12 (December 28, 2021): 716–23. http://dx.doi.org/10.52403/ijrr.20211287.
Abstract:
Introduction:- we study the intra operative evaluation of different gas mixture(oxygen 100%, O2 50%:N2O 50%, AIR on cuff pressure of PLMA. Aims and Objectives:- To study intracuff pressure changes and the change in final volume of gas mixture during inflation and deflation during intraoperative period and postoperative complications. Material and Methods:- This double blind, prospective Study was conducted in Department of Anaesthesiology, Maharishi Markandeshwar Institute of Medical Sciences and Research, Mullana, Ambala following approval from institutional ethical committee and written informed patient consent. The sample size of 120 patient aged 18 to 60 years, belonging to ASA physical status 1 and 2 undergoing surgery in general anesthesia with PLMA as airway device divided into three group on the basis of PMLA cuff gas mixture:-Group O - oxygen 100%, Group ON - Nitrous 50%: Oxygen 50%, Group A – Air. Results and Conclusion:- Combination of N2O and O2 resulted in decreased intracuff pressure and air lead to a slight increase in intracuff pressure with O2 providing relatively stable cuff pressures. Keywords: PLMA,100% Oxygen, Air, Oxygen 50% N2O 50%, Air.
31
Hussain GHAYB, Dawser. "ESTIMATION OF POWER DEPOSITION IN ICP REACTOR." MINAR International Journal of Applied Sciences and Technology 4, no. 4 (December 1, 2022): 147–57. http://dx.doi.org/10.47832/2717-8234.13.13.
Abstract:
In the present paper, the power deposited in the inductively coupled radiofrequency (RF) discharges is investigated by a two-dimensional fluid model. The discharge process was sustained in Ar / O2 gases mixture with 50:50 percentage of mixture volume. The discharge properties in the mixture obtained. An operating RF frequency of 13.56 MHz and applied voltage of 20 kV are simulated. A simple known international design of the reactor was chosen with 5 turn coil. Input power of the reactor was 1500 W. This numerical study done using plasma multiphysics model. Results show that the power deposition shows enhancement in behavior as the pressure increased. Keywords: ICP Plasma, Ar Gas, O2 Gas, Power Deposition, Electric Potential
32
Namie, Masanari, Jae-Ho Kim, and Susumu Yonezawa. "Enhanced Dyeing of Polypropylene Using Fluorine–Oxygen Gas Mixtures." Colorants 2, no. 3 (August 31, 2023): 552–64. http://dx.doi.org/10.3390/colorants2030027.
Abstract:
Surface fluorination with pure F2 gas can easily make the surface on PP (polypropylene) hydrophobic, and it causes limited dyeability, as reported in a previous paper. In this study, to produce a more hydrophilic surface, surface fluorination of PP was performed at 25 °C, total gas pressure of 13.3 kPa, and reaction time of 1 h using F2 and O2 mixtures with different proportions of F2 gas. The surface roughness of the fluorinated PP samples was about 1.5 times higher than that of the untreated sample (5 nm). Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy (XPS) results showed that the PP-derived bonds (-C-C- and -CHx) decreased because they were converted into polar groups (-C–O, -CHF-, and -CFx), which increased the surface electronegativity of the PP. The variation in the F2 gas proportion in the gas mixture significantly affected the hydrophilicity and surface composition of the PP. At F2 gas proportions of <70%, the hydrophilicity of the fluorinated PP samples was increased. Notably, the hydrophilic and negatively charged PP surface enhanced the dyeing of the polymer with basic methylene blue (MB). In contrast, at F2 gas proportions of >90%, the PP surface became hydrophobic owing to increased numbers of hydrophobic -CF3 bonds. Thus, enhanced PP dyeing can be controlled based on the composition of the F2 and O2 gas mixture.
33
Efremov, Aleksandr M., Vladimir B. Betelin, Kwang-Ho Kwon, and Dmitriy G. Snegirev. "PLASMA PARAMETERS AND KINETICS OF ACTIVE SPECIES IN HBr + Cl2 + O2 GAS MIXTURE." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 62, no. 7 (July 21, 2019): 72–79. http://dx.doi.org/10.6060/ivkkt.20196207.5947.
Abstract:
In this work, we performed the combined (experimental and model-based) study of gas-phase plasma characteristics for HBr + Cl2 + O2 gas mixture under conditions of low-pressure inductive 13.56 MHz discharge. The data on internal plasma parameters, plasma chemistry as well as the steady-state plasma composition were obtained using a combination of Langmuir probe diagnostics and 0-dimensional (global) plasma modeling. Both experimental and modeling procedures were carried out at constant total gas pressure (p = 10 mTorr), input power (W = 500 W), bias power (Wdc = 200 W) and O2 fraction in a feed gas (y(O2) = 11 %). The variable parameter was the HBr + Cl2 mixing ratio, which was changed in the range of 0 – 89 % Cl2. It was found that, under the given set of experimental conditions, the substitution of HBr for Cl2: 1) results in increasing both mean electron energy and electron density; 2) causes the mon-monotonic (with a maximum at ~ 45 % Cl2) change in Br atom density; and 3) provides an increase in O atom density at y(O2) = const. The possible impacts of HBr + Cl2 mixing ratio on Si and SiO2 etching kinetics were estimated through the analysis of model-predicted fluxes for plasma active species (Br, Cl and O atoms, positive ions).
34
Bertuglia, S., A. Colantuoni, G. Coppini, and M. Intaglietta. "Hypoxia- or hyperoxia-induced changes in arteriolar vasomotion in skeletal muscle microcirculation." American Journal of Physiology-Heart and Circulatory Physiology 260, no. 2 (February 1, 1991): H362—H372. http://dx.doi.org/10.1152/ajpheart.1991.260.2.h362.
Abstract:
Arteriolar vasomotion was characterized in the skin muscle of the unanesthetized hamster skinfold window preparation and related to the specific arterioles that give rise to the different types of activity. The arterioles were classified according to the Strahler method: order 0 was assigned to capillaries and order 4 to the largest arterioles. The arterioles showed vasomotion with a specific range of frequencies that varied according to the vessel order; the highest fundamental frequency (9.1 +/- 3.9 cycles/min) was detected in the smallest order 1 arterioles and the lowest frequency (2.1 +/- 0.9 cycles/min) in order 4 vessels. Hypoxia (8, 11, and 15% O2 gas mixture inspiration) increased the frequency of vasomotion, decreased mean and effective diameters, and reduced capillary blood flow. The effects were more pronounced with an 8 and 11% O2 gas mixture. Hypoxia caused high-frequency vasomotion to shift from order 1 and 2 arterioles to the beginning of order 3 arterioles, which in this condition dominated the daughter vessels and generated the prominent activity (24 +/- 4 cycles/min, 11% O2 gas mixture). Hypertoxia (100% O2) induced differentiated arteriolar responses. The smallest vessels showed prolonged constriction, decreased mean and effective diameters, and reduced frequency of vasomotion. Capillary blood flow was restricted. Order 3 vessels did not constrict or dilate.
35
Efremov, Alexander M., and Alexander M. Sobolev. "FEATURES OF SiO2 REACTIVE-ION ETCHING KINETICS IN CF4 + Ar + O2 AND C4F8 + Ar + O2 GAS MIXTURES." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 63, no. 9 (August 3, 2020): 21–27. http://dx.doi.org/10.6060/ivkkt.20206309.6198.
Abstract:
The effect of Ar/O2 mixing ratio on gas-phase characteristics and SiO2 etching kinetics in CF4 + Ar + O2 and C4F8 + Ar + O2 plasmas was studied under conditions of 13.56 MHz inductive RF discharge. The constant processing parameters were fraction of fluorocarbon component in a feed gas (50%) total gas pressure (6 mTorr), input power (700 W) and bias power (200 W). It was found that the full substitution of Ar for O2 in both gas systems results in non-monotonic (with a maximum at ~ 25% Ar + 25% O2) SiO2 etching rates as well as in monotonically increasing photoresist etching rate with higher absolute values for CF4-containing mixture. The steady-state densities of active species were determined using a combination of plasma diagnostics by Langmuir probes and 0-dimensional (global) plasma modeling. Corresponding results indicated that both gas systems are characterized by quite close parameters of electron and ion components while exhibit sufficient differences in the kinetics of neutral species, especially in the presence of O2. The latter produces opposite changes in F atom density as well as in effective probability of ion-assisted chemical reaction vs. Ar/O2 mixing ratio. Relationships between type of fluorocarbon component and heterogeneous process kinetics were analyzed through the set of gas-phase-related parameters (fluxes, flux-to-flux ratios) characterizing chemical etching pathways for SiO2 and formation/destruction balance for the fluorocarbon polymer film. It was suggested that the transition toward O2-rich plasma in the low-polymerizing CF4 + Ar + O2 plasma suppresses the effective probability for SiO2 + F reaction through decreasing efficiency for oxide bond breaking and desorption of etching products due to decreasing ion energy flux. Oppositely, an increase in O2 content in the high-polymerizing C4F8 + Ar + O2 mixture lifts up the effective reaction probability by decreasing fluorocarbon film thickness and providing better access of F atoms to the etched surface.
36
Hornby, L., A. L. Coates, and L. C. Lands. "Effect of analyzer on determination of mixed venous PCO2 and cardiac output during exercise." Journal of Applied Physiology 79, no. 3 (September 1, 1995): 1032–38. http://dx.doi.org/10.1152/jappl.1995.79.3.1032.
Abstract:
Cardiac output (CO) during exercise can be determined noninvasively by using the indirect Fick CO2-rebreathing technique. CO2 measurements for this technique are usually performed with an infrared analyzer (IA) or mass spectrometer (MS). However, IA CO2 measurements are susceptible to underreading in the face of high O2 concentrations because of collision broadening. We compared an IA (Ametek model CD-3A) with a MS (Marquette model MGA-1100) to see the effect this would have on mixed venous PCO2 (PVCO2) and CO measurements. After calibration with room air and a gas mixture of 5% CO2–12% O2–83% N2, both devices were tested with three different gas mixtures of CO2 in O2. For each gas mixture, IA gave lower CO2 values than did the MS (4.1% CO2: IA, 3.85 +/- 0.01% and MS, 4.13 +/- 0.01%; 9.2% CO2: IA, 8.44 +/- 0.07% and MS, 9.19 +/- 0.01%; 13.8% CO2: IA, 12.57 +/- 0.15% and MS, 13.82 +/- 0.01%). Warming and humidifying the gases did not alter the results. The IA gave lower values than did the MS for eight other medical gases in lower concentrations of O2 (40–50%). Equilibrium and exponential rebreathing procedures were performed. Values determined by the IA were > 10% higher than those determined by the MS for both rebreathing methods. We conclude that all IAs must be checked for collision broadening if they are to be used in environments where the concentration of O2 is > 21%. If collision broadening is present, then either a special high O2-CO2 calibration curve must be constructed, or the IA should not be used for both arterial PCO2 and PVCO2 estimates because it may produce erroneously low PVCO2 values, with resultant overestimation of CO.
37
Kobayashi, K., T. Hiraki, and T. Nagasakaki. "Oxidation of Pure Solid CaS with Ar-O2 Gas Mixture." High Temperature Materials and Processes 31, no. 4-5 (October 30, 2012): 667–73. http://dx.doi.org/10.1515/htmp-2012-0104.
Abstract:
SynopsisOxidation behavior of CaS in oxidizing atmosphere has been investigated for the regeneration process of desulfurization slag by oxidation. The temperature range of oxidation of CaS reagent with Ar-21%O2 gas was 973 to 1423 K. The weight gain was observed in the lower temperature range and reached at the maximum value at 1173 K while weight gain turned to decrease when the reaction temperature was higher than 1173 K. It was clarified that CaS was oxidized to CaSO4 under 1173 K or to CaO over 1373 K by the measurement of oxidation rate, XRD and thermodynamic analysis. The results strongly suggested that sulfur removal from the sulfur containing slag may be possible at temperatures of 1223 K or higher by the oxidation of with air.
38
Yoshida, Yu, Naoyuki Hatayama, and Kunihiro Seki. "Study on the Preservation with CO (PCO = 200–2,000 hPa), Resuscitation, and Heterotopic Transplantation of an Isolated Rat Heart." Cell Transplantation 18, no. 5-6 (May 2009): 535–40. http://dx.doi.org/10.1177/096368970901805-608.
Abstract:
In this experiment, CO was used as a gas mixture in a reversible relationship with O2. CO was added in a gas form mixed with O2. An isolated donor rat heart was obtained, exposed to a gas mixture such as PO2 = 1,800 hPa and PCO = 200 hPa, and PO2 = 1,000 hPa and PCO = 1,000 hPa in a 2 ATA high-pressure chamber and preserved in a refrigerator at 4°C. This report demonstrates that significant reproducibility has been verified. The heart was removed from the refrigerator 24 h later and heterotopic heart transplantation was performed in the right neck of a recipient rat and the pulsating of the transplanted heart was detected by an electrocardiogram.
39
Huang, Lijun, Chaoqiong Fang, Ting Pan, Qigang Zhu, Tiangeng Geng, Guixiang Li, Xiao Li, and Jiayuan Yu. "Hydrogen Production via Electrolysis of Wastewater." Nanomaterials 14, no. 7 (March 25, 2024): 567. http://dx.doi.org/10.3390/nano14070567.
Abstract:
The high energy consumption of traditional water splitting to produce hydrogen is mainly due to complex oxygen evolution reaction (OER), where low-economic-value O2 gas is generated. Meanwhile, cogeneration of H2 and O2 may result in the formation of an explosive H2/O2 gas mixture due to gas crossover. Considering these factors, a favorable anodic oxidation reaction is employed to replace OER, which not only reduces the voltage for H2 production at the cathode and avoids H2/O2 gas mixture but also generates value-added products at the anode. In recent years, this innovative strategy that combines anodic oxidation for H2 production has received intensive attention in the field of electrocatalysis. In this review, the latest research progress of a coupled hydrogen production system with pollutant degradation/upgrading is systematically introduced. Firstly, wastewater purification via anodic reaction, which produces free radicals instead of OER for pollutant degradation, is systematically presented. Then, the coupled system that allows for pollutant refining into high-value-added products combined with hydrogen production is displayed. Thirdly, the photoelectrical system for pollutant degradation and upgrade are briefly introduced. Finally, this review also discusses the challenges and future perspectives of this coupled system.
40
Rakhadilov, Bauyrzhan, Dastan Buitkenov, Zhuldyz Sagdoldina, Zhanat Idrisheva, Manira Zhamanbayeva, and Dauir Kakimzhanov. "Preparation and Characterization of NiCr/NiCr-Al2O3/Al2O3 Multilayer Gradient Coatings by Gas Detonation Spraying." Coatings 11, no. 12 (December 10, 2021): 1524. http://dx.doi.org/10.3390/coatings11121524.
Abstract:
This paper investigates the influence of the technological parameters of detonation spraying on the phase composition of NiCr- and Al2O3-based coatings. It was determined that the phase composition of Al2O3 coatings during detonation spraying strongly depends on the barrel filling volume with the gas mixture. The acetylene–oxygen mixture, which is the most frequently used fuel in the detonation spraying of powder materials, was used as a fuel gas. To obtain a ceramic layer based on Al2O3, spraying was performed at an acetylene–oxygen O2/C2H2 mixture ratio of 1.856; the volume of filling of the detonation gun barrel with an explosive gas mixture was 63%. To obtain a NiCr-based metallic layer, spraying was performed at the O2/C2H2 ratio of 1.063; the volume of filling of the detonation gun barrel with an explosive gas mixture was 54%. Based on a study of the effect of the detonation spraying mode on the phase composition of NiCr and Al2O3 coatings, NiCr/NiCr-Al2O3/Al2O3-based multilayer coatings were obtained. Mixtures of NiCr/Al2O3 powders with different component ratios were used to obtain multilayer gradient coatings. The structural-phase composition, mechanical and tribological properties of multilayer gradient metal–ceramic coatings in which the content of the ceramic phase changes smoothly along the depth were experimentally investigated. Three-, five- and six-layer gradient coatings were obtained by alternating metallic (NiCr) and ceramic (Al2O3) layers. The phase composition of all coatings was found to correspond to the removal of information from a depth of 20–30 μm. It was determined that the five-layer gradient coating, consisting of the lower metal layer (NiCr), the upper ceramic layer (Al2O3) and the transition layer of the mechanical mixture of metal and ceramics, is characterized by significantly higher hardness (15.9 GPa), wear resistance and adhesion strength.
41
Li, Hu, Koichi Ishii, Shun Sasaki, Mao Kamiyama, Akinori Oda, and Kazuki Denpoh. "Understanding plasma enhanced chemical vapor deposition mechanisms in tetraethoxysilane-based plasma." Journal of Vacuum Science & Technology B 41, no. 2 (March 2023): 022208. http://dx.doi.org/10.1116/6.0002409.
Abstract:
The mechanisms of plasma-enhanced chemical vapor deposition using tetraethoxysilane (TEOS)-based plasma were investigated by monitoring the plasma via experimental and computational approaches using a quadrupole mass spectrometer/residual gas analyzer and coupled plasma-gas flow simulation. For experimental measurements, plasma was generated from a TEOS/inert gas mixture, that is, Ar/TEOS or He/TEOS. The results showed that a larger number of TEOS fragments (i.e., silicon complex species) were generated in the He/TEOS plasma than in the Ar/TEOS plasma. Plasma simulation showed that the He/TEOS plasma has a higher electron temperature than the Ar/TEOS plasma, enhancing the dissociation reactions by electron impact. The spatial distributions of TEOS fragments of this mixture observed in the plasma simulation showed that the number of TEOS fragments reaching the wafer surface increased as the O2 ratio of the gas mixture increased. However, a further increase in the O2 flow rate beyond a certain ratio caused the number of signals to decrease. This is attributed to the changes in the determining step from the gas-phase reaction of SiO production to the diffusion of SiO from the portion near the inlet. We also found that metastable species such as Ar*, O2*, and O* are the main contributors to the generation of atomic oxygen (O), which is closely related to the high deposition rate.
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Huszczuk, A., BJ Whipp, and K. Wasserman. "A respiratory gas exchange simulator for routine calibration in metabolic studies." European Respiratory Journal 3, no. 4 (April 1, 1990): 465–68. http://dx.doi.org/10.1183/09031936.93.03040465.
Abstract:
We have developed a method for simulating respiratory gas exchange for on-line calibration of metabolic measurement systems. It utilizes a pump which intakes a mixture of atmospheric air and a known flow of precision-analysed calibration gas (21% CO2, 79% N2). It expels the resulting mixture with flow wave form and profiles of gas concentration which closely resemble those of normal expiration. Control of the calibration mixture's inflow allows the investigator to set any desired metabolic rate regardless of the minute ventilatory rate. This separation of metabolic from ventilatory rates provides a stringent test of the computational performance of the respiratory gas exchange measurement systems. The apparatus can reproduce any range of respiratory and metabolic performance (currently ranging from 0.2-5 l.min-1 O2 uptake and CO2 output) with accuracy +/- 2%.
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Han, Jingning, Zhifu Yin, Helin Zou, Wenqiang Wang, and Jianbo Feng. "A New Dry Etching Method with the High Etching Rate for Patterning Cross–Linked SU–8 Thick Films." Journal of Electrical Engineering 67, no. 3 (May 1, 2016): 212–16. http://dx.doi.org/10.1515/jee-2016-0030.
Abstract:
Abstract Photo sensitive polymer SU-8, owing to its excellent mechanical properties and dielectric properties on polymerization, is widely used in MEMS device fabrications. However, the removing, stripping or re-patterning of the cross-linked SU-8 is a difficult issue. In this paper, CF4/O2 gas mixture provided by a plasma asher equipment was used for the patterning of cross-linked SU-8 material. The RF power, the temperature of the substrate holder, chamber pressure and gas concentration were optimized for the cross-linked SU-8 etching process. When the CF4/O2 mixture contains about 5%CF4 by volume, the etching rate can be reached at 5.2 μm/min.
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Qadir, Salman, Muhammad Ahsan, and Arshad Hussain. "Computational Fluid Dynamics Analysis of a Hollow Fiber Membrane Module for Binary Gas Mixture." Gases 3, no. 2 (May 22, 2023): 77–91. http://dx.doi.org/10.3390/gases3020005.
Abstract:
The membrane gas separation process has gained significant attention using the computational fluid dynamics (CFD) technique. This study considered the CFD method to find gas concentration profiles in a hollow fiber membrane (HFM) module to separate the binary gas mixture. The membrane was considered with a fiber thickness where each component’s mass fluxes could be obtained based on the local partial pressures, solubility, diffusion, and the membrane’s selectivity. COMSOL Multiphysics was used to solve the numerical solution at corresponding operating conditions and results were compared to experimental data. The two different mixtures, CO2/CH4 and N2/O2, were investigated to obtain concentration gradient and mass flux profiles of CO2 and O2 species in an axial direction. This study allows assessing the feed pressure’s impact on the HFM system’s overall performance. These results demonstrate that the increment in feed pressures decreased the membrane system’s separation performance. The impact of hollow fiber length indicates that increasing the active fiber length has a higher effective mass transfer region but dilutes the permeate-side purities of O2 (46% to 28%) and CO2 (93% to 73%). The results show that increasing inlet pressure and a higher concentration gradient resulted in higher flux through the membrane.
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Ryu, Hyun Wook, Yong Joo Park, Hyo Sup Noh, and Jin Seong Park. "Characteristics of SnO2 Thin Films Deposited by RF Magnetron Sputtering." Materials Science Forum 449-452 (March 2004): 993–96. http://dx.doi.org/10.4028/www.scientific.net/msf.449-452.993.
Abstract:
SnO2 thin films were prepared on SiO2/Si substrate by RF-Magentron Sputtering method, varying the deposition time and Ar-to-O2 flow ratio. The post-annealing was conducted at 500 oC and 700 oC in Ar and O2 atmosphere, respectively. Film characteristics were very sensitive to the gas flow ratio during the deposition and the conditions of post-annealing. The Film thickness decreased with decreasing of Ar flow ratio at a constant amount (50 sccm) of total gas flow. Especially, the film deposited under Ar-O2 mixture gas (Ar-to-O2 ratio of 50%) showed clearly aggregated morphology of small particles (cauliflower) in a wide range of area. In the annealed films, these cauliflowers separated some small grains, decreasing the film thickness.
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Park, Jin-Seong, In-Sung Park, Seon Yong Kim, Taehoon Lee, Jinho Ahn, Tae-Hun Shim, and Jea-Gun Park. "Plasma Etching of SiO2 with CF3I Gas in Plasma-Enhanced Chemical Vapor Deposition Chamber for In-Situ Cleaning." Science of Advanced Materials 11, no. 12 (December 1, 2019): 1667–72. http://dx.doi.org/10.1166/sam.2019.3634.
Abstract:
Non-global-warming CF3I gas has been investigated as a removal etchant for SiO2 film. Thermally fabricated SiO2 films were etched by the plasma generated with a gas mixture of CF3I and O2 (CF3I/O2) in the plasma-enhanced chemical vapor deposition chamber. The etch rate of SiO2 films was studied along with the process parameters of plasma etching such as chamber pressure, etching gas flow ratio of CF3I to CF3I/O2, plasma power, and chamber temperature. Increasing the chamber pressure from 400 to 1,000 mTorr decreased the etch rate of SiO2 film. The etch rate of this film showed a minimum value at a gas flow ratio of 0.71 in CF3I to CF3I/O2 and then increased at a higher CF3I gas flow ratio. In addition, the elevated plasma power increased the etch rate. However, the chamber temperature has little effect on the etch rate of SiO2 films. When only CF3I gas without O2 was supplied for etching, polymerized fluorocarbon was formed on the surface, indicating the role of oxygen in ashing the polymerized fluorocarbon during the etching process.
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Joyce, C. J., A. B. Baker, and R. R. Kennedy. "Gas uptake from an unventilated area of lung: computer model of absorption atelectasis." Journal of Applied Physiology 74, no. 3 (March 1, 1993): 1107–16. http://dx.doi.org/10.1152/jappl.1993.74.3.1107.
Abstract:
A computer model of gas uptake from an area of nonventilated lung, such as a pulmonary lobe with an occluded bronchus or an alveolus with an occluded airway, is presented. Previous analyses have assumed that when an inert gas is present, equilibration of O2 and CO2 with mixed venous blood is sufficiently rapid to be treated as instantaneous. This is valid for insoluble gases such as N2 or He when the fractional concentration of inspired O2 (FIO2) is < or = 0.6 but is invalid for a relatively soluble gas such as N2O. When a mixture of O2 and an inert gas is breathed, the time for an area of unventilated lung to collapse depends on the solubility of the inert gas and FIO2. When the solubility is low (N2 or He), collapse takes longer than when 100% O2 is breathed, and the lower the FIO2 the longer the time to collapse. When the gas is more soluble (N2O) and FIO2 is > 0.3, collapse is more rapid than when 100% O2 is breathed.
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Bhattacharya, Deb Sankar, Thorben Swirski, Burkhard Böhm, Raimund Ströhmer, and Thomas Trefzger. "Study on the performance of a resistive Micromegas in a controlled O2 environment." Journal of Instrumentation 17, no. 06 (June 1, 2022): P06023. http://dx.doi.org/10.1088/1748-0221/17/06/p06023.
Abstract:
Abstract Being the state of the art, the Micro-Pattern Gaseous Detectors (MPGD) are widely accepted in almost every particle collider experiment. Micromegas is a type of MPGD which is famous for its simple single-stage amplification, high and stable gain, low ion feedback, and excellent spatial and temporal resolutions. The chance of O2 contamination in a gaseous detector is not negligible as the abundance of O2 in air is nearly 21%. Contamination of detector-gas by O2 may occur due to insufficient gas-tightness or the use of long plastic pipes. Being an electronegative gas, O2 attach with the electrons inside a gaseous detector and influence the performance. The concern is higher when the detector has a large scale extension. We are reporting our measurements on the diffusion of O2 through a couple of commonly used plastic pipes. Then, in a hermetic gas system, by infusing O2 in a controlled and precise way, we have measured the effects of O2 on the performance of a resistive Micromegas. In pure Ar-CO2 mixture, we have also compared the gas-gain of the Micromegas with simulation to better estimate the gas-gap. The effects of temperature and pressure fluctuations on our study have also been investigated.
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Tsuruta, Akihiro, Takafumi Akamatsu, Kojiro Naito, Takayoshi Hirai, Seiichiro Murase, and Yoshitake Masuda. "Gas Sensing Properties of High-Purity Semiconducting Single-Walled Carbon Nanotubes for NH3, H2, and NO." ECS Journal of Solid State Science and Technology 10, no. 12 (December 1, 2021): 121004. http://dx.doi.org/10.1149/2162-8777/ac4218.
Abstract:
Gas sensors are advantageous as they can be applied in various fields. The metal-oxide semiconductor gas sensor is the most widely used gas sensor. In this study, the gas-sensing properties of high-purity semiconducting single-walled carbon nanotubes (SWCNTs), which behave as p-type semiconductors, are analyzed at temperatures of 50, 100, and 200 °C for NH3, H2, and NO at various O2 concentrations. The SWCNTs are separated from a mixture of metallic and semiconducting SWCNTs based on the agarose gel column chromatography. The SWCNT gas sensor responds to all the gases in 20% O2, and the gas selectivity to NH3 and H2 is controlled by the operating temperature. NO transforms to NO2 in the presence of O2 and decreases the resistance of the sensor as an oxidizing gas. The sensor can detect NH3, H2, and NO without O2. Along with the good conductivity of the SWCNTs, the good conductive paths between the SWCNTs through the semiconducting polymer dispersant reduce the noise of the sensor resistance and enable the detection of small changes in the resistance to minimal gas concentration.
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Čížek, Milan. "Reduction of nitrogen oxide by ammonia. Oxidation state of V2O5/Al2O3 catalysts and reaction mechanism." Collection of Czechoslovak Chemical Communications 55, no. 10 (1990): 2390–94. http://dx.doi.org/10.1135/cccc19902390.
Abstract:
When the (NO + NH3 + O2) reaction is carried out over V2O5/Al2O3, the catalysts are partially reduced, and prereduced catalysts are oxidized by the reaction mixture at a slower rate than by an O2 + N2 mixture. The degree of catalyst reduction in the (NO + NH3 + O2) reaction depends on the gas phase composition and particularly on the vanadium loading of the catalyst. The initial oxidation state of catalyst has an effect on the catalyst activity for the reaction. Rate-determining reduction and oxidation steps of the so-called reduction-oxidation mechanism are proposed on the basis of a comparison of the reduction and oxidation of the catalyst by the reaction components.