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Li, Yalong, Xiaoxing Zhang, Yalong Xia, Yi Li, Zhuo Wei, Yi Wang, and Song Xiao. "Study on the Compatibility of Eco-Friendly Insulating Gas C5F10O/N2 and C5F10O/Air with Copper Materials in Gas-Insulated Switchgears." Applied Sciences 11, no. 1 (December 28, 2020): 197. http://dx.doi.org/10.3390/app11010197.
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Sulfur hexafluoride (SF6) is widely used in the power industry because of its excellent insulation and arc extinguishing performance. However, the high greenhouse effect of this material is being restricted by many countries around the world, thereby discouraging its usage. As a potential alternative to SF6, the compatibility of C5F10O with conductive copper materials used in electrical equipment is of great significance in ensuring the safe and stable operation of environmentally friendly gas-insulated equipment. In this paper, the interaction among C5F10O/N2, C5F10O/air gas mixture, and copper was studied via experiments and simulations. When the C5F10O/N2 (or air) gas mixture comes in contact with copper at the gas–solid interface, a small portion of C5F10O is decomposed to form C3F6 (or C3F6 and C3F6O) at high temperatures. Meanwhile, at low temperatures (120 °C), the C5F10O/air gas mixture becomes more compatible with copper than with the C5F10O/N2 gas mixture. When the experiment temperatures range between 170 °C and 220 °C, the compatibility of the C5F10O/air gas mixture with copper is significantly inferior to its compatibility with copper. Under high temperatures, the C5F10O/air gas mixture shows severe corrosion on the copper surface due to the presence of O2, forms a thick cubic grain, and emits irritating gases. The simulations show that the carbonyl group in C5F10O is chemically active and can be easily adsorbed on the copper surface. An anti-corrosion treatment must be performed on copper materials in manufacturing equipment. The findings provide an important reference for the application of C5F10O gas mixture.
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Nechmi, Houssem Eddine, Michail Michelarakis, Abderrahmane (Manu) Haddad, and Gordon Wilson. "Clarifications on the Behavior of Alternative Gases to SF6 in Divergent Electric Field Distributions under AC Voltage." Energies 14, no. 4 (February 18, 2021): 1065. http://dx.doi.org/10.3390/en14041065.
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Negative and positive partial discharge inception voltages and breakdown measurements are reported in a needle-plane electrode system as a function of pressure under AC voltage for natural gases (N2, CO2, and O2/CO2), pure NovecTM gases (C4F7N and C5F10O) and NovecTM in different natural gas admixtures. For compressed 4% C4F7N–96% CO2 and 6% C5F10O–12% O2–82% CO2 gas mixtures, the positive-streamer mode is identified as the breakdown mechanism. Breakdown and negative partial discharge inception voltages of 6% C5F10O–12% O2–82% CO2 are higher than those of 4% C4F7N–96% CO2. At 8.8 bar abs, the breakdown voltage of 6% C5F10O–12% O2–82% CO2 is equal to that of 12.77% O2–87.23% CO2 (buffer gas). Synergism in negative partial discharge inception voltage/electric field fits with the mean value and the sum of each partial pressure individually component for a 20% C4F7N–80% CO2 and 6% C5F10O–12% O2–82% CO2, respectively. In 9% C4F7N–91% CO2, the comparison of partial discharge inception electric fields is Emax (CO2) = Emax(C4F7N), and Emax (12.77% O2–87.23% CO2) = Emax(C5F10O) in 19% C5F10O–81%(12.77% O2–87.23% CO2). Polarity reversal occurs under AC voltage when the breakdown polarity changes from negative to positive cycle. Polarity reversal electric field EPR was quantified. Fitting results show that EPR (CO2) = EPR(9% C4F7N–91% CO2) and EPR(SF6) = EPR (22% C4F7N–78% CO2). EPR (4% C4F7N–96% CO2) = EPR (12.77% O2–87.23% CO2) and EPR (6% C5F10O–12% O2–82% CO2) < EPR (4% C4F7N–96% CO2) < EPR (CO2).
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Zhang, Yue, Xiaoxing Zhang, Yi Li, Yalong Li, Qi Chen, Guozhi Zhang, Song Xiao, and Ju Tang. "Effect of oxygen on power frequency breakdown voltage and decomposition characteristics of the C5F10O/N2/O2 gas mixture." RSC Advances 9, no. 33 (2019): 18963–70. http://dx.doi.org/10.1039/c9ra03275d.
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C5F10O gas mixture is a SF6 potential substitute with high insulation strength and is a new type of environmentally friendly insulating gas. By adding oxygen to C5F10O gas mixture, insulation strength can be improved and carbon deposition can be suppressed.
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She, Congdong, Fuping Zeng, Liangjun Dai, Long Li, Qiang Yao, and Ju Tang. "Degradation Behaviors and Mechanism of Nitrile Butadiene Rubber Caused by Insulating Medium C5F10O." Polymers 15, no. 10 (May 12, 2023): 2282. http://dx.doi.org/10.3390/polym15102282.
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C5F10O is a promising insulating medium in the manufacturing of environmentally friendly gas-insulated switchgears (GISs). The fact that it is not known whether it is compatible with sealing materials used in GISs limits its application. In this paper, the deterioration behaviors and mechanism of nitrile butadiene rubber (NBR) after prolonged exposure to C5F10O are studied. The influence of C5F10O/N2 mixture on the deterioration process of NBR is analyzed through a thermal accelerated ageing experiment. The interaction mechanism between C5F10O and NBR is considered based on microscopic detection and density functional theory. Subsequently, the effect of this interaction on the elasticity of NBR is calculated through molecular dynamics simulations. According to the results, the polymer chain of NBR can slowly react with C5F10O, leading to deterioration of its surface elasticity and loss of inside additives, mainly ZnO and CaCO3. This consequently reduces the compression modulus of NBR. The interaction is related to CF3 radicals formed by the primary decomposition of C5F10O. The molecular structure of NBR will be changed in the molecular dynamics simulations due to the addition reaction with CF3 on NBR’s backbone or branched chains, resulting in changes in Lame constants and a decrease in elastic parameters.
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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.
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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.
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Wu, King Kung, and Wen Chung Chang. "High-Quality Polysilicon Thin Film Recrystallization by Laser Annealing." Advanced Materials Research 382 (November 2011): 26–29. http://dx.doi.org/10.4028/www.scientific.net/amr.382.26.
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Amorphous silicon (a:Si) recrystalized to poly-silicon (poly:Si) in different gas environments by excimer laser annealing (ELA) is studied. Variations of threshold laser power for the generation of surface ablation in pure N2 gas and the mixture of N2:98% and O2:2% environments are also investigated, respectively. From experiments, it is found the combination of N2:98% and O2:2% gas can enhance the threshold laser power from 320mJ/cm2 to 390mJ/cm2 for the suppressing of surface ablation phenomenon. In the condition of average grain over 0.25um, the process window (i.e. laser power for processing ability) is 30mJ/cm2 for pure N2 only, but is 50mJ/cm2 for the combination of N2:98% and O2:2%.
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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.
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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.
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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.
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Xiao, Dezhi, Cheng Cheng, Jie Shen, Yan Lan, Hongbing Xie, Xingsheng Shu, Yuedong Meng, Jiangang Li, and Paul K. Chu. "Characteristics of atmospheric-pressure non-thermal N2 and N2/O2 gas mixture plasma jet." Journal of Applied Physics 115, no. 3 (January 21, 2014): 033303. http://dx.doi.org/10.1063/1.4862304.
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Pramanik, Bimal Kumar, and AKM Akhtar Hossain. "UV Emission from N2/O2 Pulse Microwave Plasma." Rajshahi University Journal of Science 38 (October 10, 2013): 1–8. http://dx.doi.org/10.3329/rujs.v38i0.16543.
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The emission spectrum from pulse microwave discharge of N2/O2 gas mixture in the UV range (from 200 400 nm) was studied in a cylindrical quartz tube aiming to apply it as a mercury free UV light source. The UV light in the 200-280 nm range has germicidal effect which can be used for water purification. In our previous work we used continuous microwave power to produce UV emission from N2/O2 discharge. In the present work we used pulse microwave power instead of continuous microwave power. We studied the dependence of pulse width and pulse interval on the intensity of the UV emission from N2/O2 discharge. Experimental results showed that the UV emission intensity emitted from N2/O2 gas discharge in 200- 400 nm region does not vary with pulse width and pulse interval but depends on applied average power. DOI: http://dx.doi.org/10.3329/rujs.v38i0.16543 Rajshahi University J. of Sci. 38, 01-08 (2010)
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Chen, Gao Cheng, Li Ming He, Bing Bing Zhao, Hua Lei Zhang, Zi Chen Zhao, Hao Zeng, Jian Ping Lei, and Xiong Liu. "Effects of Working Medium Gases on Emission Spectral and Temperature Characteristics of a Plasma Igniter." Journal of Spectroscopy 2019 (August 29, 2019): 1–10. http://dx.doi.org/10.1155/2019/5395914.
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Ar, N2, O2, and N2-O2 mixture under different O2 components were separately used as the working medium gas of a plasma igniter to study the influence of working-medium-gas type and O2 concentration on emission spectral and temperature characteristics of a direct-current arc plasma igniter. The emission spectra of the plasma jet were also analyzed using the optical emission spectroscopy method, and the influence rule of working medium gas and O2 concentration on electron temperature and vibrational temperature of the plasma jet was calculated and analyzed. The experimental results show that the emission spectra of the plasma jet had significant differences when diverse working gases were used as the working medium of the igniter. With increasing O2 concentration in the working medium gas, the spectral line intensity of oxygen-containing particles in emission spectra of the plasma jet was significantly enhanced, and the spectral intensities of nitrogen-containing particles, NO molecular bands, the second positive system of N2C3∏u−B3∏g, and the first negative system of N2+B2∑u+−X2∑u+ were also enhanced obviously. Both electron and vibrational temperature of the plasma jet increased gradually with increasing O2 concentration in the working medium gas, and first increased and then decreased with increasing axial distance from the plasma jet.
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Oyama, K. I., M. Shimoyama, J. Y. Liu, and C. Z. Cheng. "Possible interaction between thermal electrons and vibrationally excited N<sub>2</sub> in the lower E-region." Annales Geophysicae 29, no. 3 (March 25, 2011): 583–90. http://dx.doi.org/10.5194/angeo-29-583-2011.
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Abstract. As one of the tasks to find the energy source(s) of thermal electrons, which elevate(s) electron temperature higher than neutral temperature in the lower ionosphere E-region, energy distribution function of thermal electron was measured with a sounding rocket at the heights of 93–131 km by the applying second harmonic method. The energy distribution function showed a clear hump at the energy of ~0.4 eV. In order to find the reason of the hump, we conducted laboratory experiment. We studied difference of the energy distribution functions of electrons in thermal energy range, which were measured with and without EUV radiation to plasma of N2/Ar and N2/O2 gas mixture respectively. For N2/Ar gas mixture plasma, the hump is not clearly identified in the energy distribution of thermal electrons. On the other hand for N2/O2 gas mixture, which contains vibrationally excited N2, a clear hump is found when irradiated by EUV. The laboratory experiment seems to suggest that the hump is produced as a result of interaction between vibrationally excited N2 and thermal electrons, and this interaction is the most probable heating source for the electrons of thermal energy range in the lower E-region. It is also suggested that energy distribution of the electrons in high energy part may not be Maxwellian, and DC probe measures the electrons which are non Maxwellian, and therefore "electron temperature" is calculated higher.
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Hsu, Jin-Cherng, Yung-Hsin Lin, and Paul W. Wang. "X-ray Photoelectron Spectroscopy Analysis of Nitrogen-Doped TiO2 Films Prepared by Reactive-Ion-Beam Sputtering with Various NH3/O2 Gas Mixture Ratios." Coatings 10, no. 1 (January 4, 2020): 47. http://dx.doi.org/10.3390/coatings10010047.
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Nitrogen-doped TiO2 films were prepared by reactive ion-beam sputtering deposition (IBSD) in a mixed atmosphere of NH3 and O2 at a substrate temperature of 400 °C. X-ray photoelectron spectra revealed the presence of six ions, i.e., N3−, N2−, N1−, N+, N2+, and N3+, respectively, in the films. The amorphous films had complex, randomly oriented chemical bonds. The Tauc–Lorentz model was employed to determine the bandgap energy of the amorphous films prepared using different NH3/O2 gas mixing ratios by ellipsometry. In addition, the optical constants of the films were measured. With the increase in the NH3/O2 gas mixture ratio to 3.0, the bandgap of N-doped TiO2 narrowed to ~2.54 eV.
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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.
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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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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.
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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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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.
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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.
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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.
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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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RUIZ-CAPILLAS, CLAUDIA, and ANTONIO MORAL. "Formation of Biogenic Amines in Bulk-Stored Chilled Hake (Merluccius merluccius L.) Packed under Atmospheres." Journal of Food Protection 64, no. 7 (July 1, 2001): 1045–50. http://dx.doi.org/10.4315/0362-028x-64.7.1045.
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The production of biogenic amines in the lots of whole hake stored bulk under a controlled or modified atmosphere for 12 days with the gas mixture 40% CO2:40% O2:20% N2 and after packing in trays under a modified atmosphere in the same mixture of gases or with air was studied. Results indicated a close relation between the development of trimethylamine nitrogen (TMA-N) and the sensory parameters gill appearance and odor but not with the general appearance of the skin and eyes. These results were related to changes observed in the concentration of gases (CO2 and O2) during storage containers and trays. The lot of bulk-stored whole hake in controlled atmospheres for 12 days with the gas mixture 40% CO2:40% O2:20% N2 and then packed in trays with the same atmosphere exhibited TMA-N levels below the 12.5 mg/100 g limit designated by the legislation in force (Directive 91/143/EU) on day 31 of storage when the sensory parameters general appearance and skin and gill color were not rejected. Histamine and tyramine levels were less than 1 mg/kg, putrescine levels were approximately 7 mg/kg, and cadaverine and agmatine levels were 33.91 and 20.33 mg/100 g, respectively.
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Moreno Fernández, Harol, Marco Zangrando, Guillaume Sauthier, Alejandro R. Goñi, Vincent Carlino, and Eric Pellegrin. "Towards chemically neutral carbon cleaning processes: plasma cleaning of Ni, Rh and Al reflective optical coatings and thin Al filters for free-electron lasers and synchrotron beamline applications." Journal of Synchrotron Radiation 25, no. 6 (October 25, 2018): 1642–49. http://dx.doi.org/10.1107/s1600577518014017.
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The choice of a reflective optical coating or filter material has to be adapted to the intended field of application. This is mainly determined by the required photon energy range or by the required reflection angle. Among various materials, nickel and rhodium are common materials used as reflective coatings for (soft) X-ray mirrors. Similarly, aluminium is one of the most commonly used materials for extreme ultraviolet and soft X-ray transmission filters. However, both of these types of optics are subject to carbon contamination, which can be increasingly problematic for the operation of the high-performance free-electron laser and synchrotron beamlines. As an attempt to remove this type of contamination, an inductively coupled plasma source has been used in conjunction with N2/O2/H2 and N2/H2 feedstock gas plasmas. Results from the chemical surface analysis of the above materials before and after plasma treatment using X-ray photoelectron spectroscopy are reported. It is concluded that a favorable combination of an N2/H2 plasma feedstock gas mixture leads to the best chemical surface preservation of Ni, Rh and Al while removing the carbon contamination. However, this feedstock gas mixture does not remove C contamination as rapidly as, for example, an N2/O2/H2 plasma which induces the surface formation of NiO and NiOOH in Ni and RhOOH in Rh foils. As an applied case, the successful carbon removal from ultrathin Al filters previously used at the FERMI FEL1 using an N2/H2 plasma is demonstrated.
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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.
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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.
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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.
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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.
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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.
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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.
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Palharini, Maria Cecília de Arruda, Angelo Pedro Jacomino, Ana Luíza Pinheiro, Marcos José Trevisan, and Claire Isabel Grígoli de Luca Sarantópoulos. "Dynamics of gas levels inside packages containing minimally processed Pera orange." Food Science and Technology 32, no. 4 (September 11, 2012): 742–46. http://dx.doi.org/10.1590/s0101-20612012005000100.
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The purpose of this study was to evaluate the changes in concentrations of O2 and CO2 inside packages of minimally processed Pera orange. Previously selected oranges that were washed, sanitized, and chilled were peeled using hydrothermal treatment (immersion of fruits in water at 50 °C for 8 minutes). The peeled oranges were then packed in five different plastic packages under passive and active modified atmosphere (5% O2 + 10% CO2 + 85% N2). The fruits were stored at 6 °C and 12 °C. The package headspace gas composition was evaluated for twelve days at 6 °C and nine days at 12 °C. The polypropylene film (32 µm) promoted modified atmosphere similar to that initially injected (5% O2 + 10% CO2 + 85% N2) at 6 °C and 12 °C. With regard to the atmosphere modification system, the injection of a gas mixture anticipated achieving an equilibrium atmosphere inside the packages at 12 °C. At 6 °C, the gas composition inside the packages was kept close to that of the injection, but the equilibrium was not verified.
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Esposito, Elisa, Irene Mazzei, Marcello Monteleone, Alessio Fuoco, Mariolino Carta, Neil McKeown, Richard Malpass-Evans, and Johannes Jansen. "Highly Permeable Matrimid®/PIM-EA(H2)-TB Blend Membrane for Gas Separation." Polymers 11, no. 1 (December 30, 2018): 46. http://dx.doi.org/10.3390/polym11010046.
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The effect on the gas transport properties of Matrimid®5218 of blending with the polymer of intrinsic microporosity PIM-EA(H2)-TB was studied by pure and mixed gas permeation measurements. Membranes of the two neat polymers and their 50/50 wt % blend were prepared by solution casting from a dilute solution in dichloromethane. The pure gas permeability and diffusion coefficients of H2, He, O2, N2, CO2 and CH4 were determined by the time lag method in a traditional fixed volume gas permeation setup. Mixed gas permeability measurements with a 35/65 vol % CO2/CH4 mixture and a 15/85 vol % CO2/N2 mixture were performed on a novel variable volume setup with on-line mass spectrometric analysis of the permeate composition, with the unique feature that it is also able to determine the mixed gas diffusion coefficients. It was found that the permeability of Matrimid increased approximately 20-fold with the addition of 50 wt % PIM-EA(H2)-TB. Mixed gas permeation measurements showed a slightly stronger pressure dependence for selectivity of separation of the CO2/CH4 mixture as compared to the CO2/N2 mixture, particularly for both the blended membrane and the pure PIM. The mixed gas selectivity was slightly higher than for pure gases, and although N2 and CH4 diffusion coefficients strongly increase in the presence of CO2, their solubility is dramatically reduced as a result of competitive sorption. A full analysis is provided of the difference between the pure and mixed gas transport parameters of PIM-EA(H2)-TB, Matrimid®5218 and their 50:50 wt % blend, including unique mixed gas diffusion coefficients.
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Komarov, Ivan, Daria Kharlamova, Bulat Makhmutov, Sofia Shabalova, and Ilya Kaplanovich. "Natural Gas-Oxygen Combustion in a Super-Critical Carbon Dioxide Gas Turbine Combustor." E3S Web of Conferences 178 (2020): 01027. http://dx.doi.org/10.1051/e3sconf/202017801027.
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The paper presents results for chemical kinetics of combustion process in the combustor of oxy-fuel cycle super-critical carbon dioxide gas turbine based on the Allam thermodynamic cycle. The work shows deviation of the normal flame propagation velocity for the case of transition from the traditional natural gas combustion in the N2 diluent environment to the combustion at super-high pressure up to 300 bar in CO2 diluent. The chemical kinetics parametric study involved the Chemkin code with the GRI-Mesh 3.0 kinetic mechanism. This mechanism provides good correspondence between calculation results and test data. The CO2 and N2 diluents temperature, pressure and contents influence the flame propagation velocity and the chemical kinetics parameters in the two gas turbine types. It is demonstrated that the CO2 diluent slows down chemical reactions stronger than the N2 one. The flame propagation velocity in carbon dioxide is four time smaller than in the N2 one. In the oxy-fuel cycle combustor a pressure increase reduces the flame propagation velocity. Increase of the CO2 content from 60 to 79% reduces the flame propagation velocity for 65% at atmospheric pressure and for 94% at super-critical pressure. An increase of the combustor inlet mixture temperature from 300 to 1100 K at super-critical pressure causes the flame propagation velocity increase for 94%. The flame propagation velocities compatible with the traditional gas turbines may be reached at the CO2 diluent content of the O2 + CO2 mixture in the active combustion zone must be below 50%.
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Nie, Masaki, Hirosuke Kobayashi, Motoaki Sugawara, Tomoyuki Tomita, Kuniyoshi Ohara, and Hirokuni Yoshimura. "Helium inhalation enhances vasodilator effect of inhaled nitric oxide on pulmonary vessels in hypoxic dogs." American Journal of Physiology-Heart and Circulatory Physiology 280, no. 4 (April 1, 2001): H1875—H1881. http://dx.doi.org/10.1152/ajpheart.2001.280.4.h1875.
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There are theoretical and experimental indications that the presence of He as a balance gas markedly increase the diffusion velocity of other gases contained in a gas mixture. We allowed dogs with pulmonary vasoconstriction induced by hypoxia to inhale a mixture of 5 parts per million (ppm) of nitric oxide (NO) and O2 balanced with He (NO in He) instead of N2 (NO in N2). The dilating effect of NO in He and NO in N2 on the pulmonary artery was evaluated by determining conventional pulmonary hemodynamic parameters, mean pulmonary artery (PA) pressure (MPAP), and pulmonary vascular resistance indexed to body surface area (PVRI), pulmonary impedance ( Z), and the recently developed hemodynamic index, time-corrected wave intensity (WI). The main findings in this study were as follows: 1) hypoxia increased MPAP, PVRI, Z at 0 Hz ( Z 0), Z at the first harmonics, characteristic impedance ( Z c), the reflection coefficient (Γ), and the first peak of WI; 2) NO in N2 reduced Z 0and Γ; and 3) NO in He reduced the first peak of WI and reduced Z 0 and Γ more than NO in N2. The enhanced vasodilatory effect of NO in He might be associated with facilitated diffusion of NO diluted in the gas mixture with He. In conclusion, increased efficacy of NO in He offers the possibility to reduce the inhaled NO concentration.
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Kusworo, Tutuk Djoko, Ahmad Fauzi Ismail, Azeman Mustafa, and Kang Li. "THE EFFECT OF TYPE ZEOLITE ON THE GAS TRANSPORT PROPERTIES OF POLYIMIDE-BASED MIXED MATRIX MEMBRANES." Reaktor 12, no. 2 (November 8, 2008): 68. http://dx.doi.org/10.14710/reaktor.12.2.68-77.
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The permeation rates of O2, N2, CO2 and CH4 has been studied for polyimide-polyethersulfone (PI/PES) blends-zeolite mixed matrix membranes synthesized in our laboratory. The study investigated the effect of zeolite loading and different zeolite type on the gas separation performance of these mixed matrix membranes. Frequency shifts and absorption intensity changes in the FTIR spectra of the PI/PES blends as compared with those of the pure polymers indicate that there is a mixing of polymer blends at the molecular level. Differential scanning calorimetry measurements of pure and PI/PES blends membranes have showed one unique glass transition temperature that supports the miscible character of the PI/PES mixture. The PI/PES-zeolite 4A mixed matrix membrane with 25 wt % zeolite loading produced the highest O2/N2 and CO2/CH4 selectivity of around 7.45 and 46.05, respectively.
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Li, Mei, Xiang Yu Zhao, Wei Shao, Chuan Bao Ma, Rui Xue Zheng, and Ya Dong Chen. "Thermal Stability of an Epoxy Adhesive." Advanced Materials Research 1053 (October 2014): 257–62. http://dx.doi.org/10.4028/www.scientific.net/amr.1053.257.
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An epoxy adhesive and its curing agent are tested using differential scaning calorimetry under different atmospheres and after different exposure times to natural air to analyze its thermal properties. The results show that after the pure epoxy, the curing agent and the adhesive mixture of them are exposed in natural air for different period of time, all show different levels of decline in thermal stability and more complicated reactions when tested in the DSC and TGA in O2 and air, while the thermal properties remain stable when they are tested in an inert gas like N2. And according to the mechanical property tests and SEM results, the mechanical properties of the adhesive mixture in N2 are better than that in air. The results indicate that inert gas can protect the property of this kind of adhesive and thus increase its bond strength.
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Takahashi, Akihiko, and Kiyoto Nishijima. "Numerical Analysis of Electrical Breakdown Induced by Laser Irradiation in N2/O2 Gas Mixture." Japanese Journal of Applied Physics 34, Part 1, No. 5A (May 15, 1995): 2471–75. http://dx.doi.org/10.1143/jjap.34.2471.
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KAMBARA, S., R. KURIYAMA, T. OSAKABE, and K. YUKIMURA. "Hydrogen oxidation in H2/O2/N2 gas mixture by pulsed DBD at atmospheric pressure." International Journal of Hydrogen Energy 33, no. 22 (November 2008): 6792–99. http://dx.doi.org/10.1016/j.ijhydene.2008.07.024.
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Galakhova, Anastasiia, and Gisbert Riess. "Fast gas chromatography–mass spectrometry method for the detection of gas phase composition of polyurethane foam and its role in foam thermal conductivity." Journal of Cellular Plastics 56, no. 5 (March 17, 2020): 531–45. http://dx.doi.org/10.1177/0021955x20912206.
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This paper presents an enhanced gas chromatography–mass spectrometry method for the separation of cell gases in polyurethane foam. The novel method was then tested on several polyurethane foams produced at different mixing times, showing successful results. The measurement of gas content in polyurethane foams has been rarely considered in published literature. This parameter, indeed, plays a critical role in the deterioration of polyurethane foam thermal conductivity. This is because of the diffusion of gases which is the main mechanism of foam aging. Hence, an improved gas chromatography–mass spectrometry method was developed to offer simultaneous separation of several types of gas in only one column, using gas chromatography as its main concept. The composition of a sample gas consisting of N2, O2, CO2, and C5H10 was accurately calculated by measuring the ratio of each peak area on the chromatograms, with argon being used for sampling. This fast and simple method was found to be useful, on one hand for the accurate determination of C5H10 and CO2 cell gases used as blowing agents, and on the other hand for N2 and O2 air gases that diffuse rapidly from the surrounding environment into foam cells. The effect of mixing time on foam kinetics, cellular structure, foam thermal conductivity, and the overall thermal conductivity of cell gas mixture was also investigated. By complex analysis of foam density, the presence of open cells, cell size, and thermal conductivity of cell gas mixture, the lowest measured value of foam thermal conductivity was explained. The major goal of these experiments was to show the importance of foam cell gas analysis, together with foam structure, which is uniquely done to contribute to the understanding of polyurethane foam thermal conductivity. The thermal conductivity of cell gas mixture is considered as an example of the potential applications of this novel gas chromatography–mass spectrometry method.
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Lee, W. H., J. G. Lee, and P. J. Reucroft. "XPS study of carbon fiber surfaces treated by thermal oxidation in a gas mixture of O2/(O2+N2)." Applied Surface Science 171, no. 1-2 (February 2001): 136–42. http://dx.doi.org/10.1016/s0169-4332(00)00558-4.
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Badmaev, S. D., N. O. Akhmetov, A. A. Pechenkin, V. A. Sobyanin, and V. N. Parmon. "Low temperature partial oxidation of dimethyl ether to hydrogen-rich gas over CuO-CeO2/γ-Al2O3 catalysts for fuel cell feeding." Доклады Академии наук 487, no. 4 (August 27, 2019): 396–400. http://dx.doi.org/10.31857/s0869-56524874396-400.
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The promise of СuO-CeO2/γ-Al2O3 catalysts for partial oxidation of dimethyl ether (DME) to hydrogen-rich gas for fuel cell feeding was demonstrated. The catalysts provided complete conversion of DME to hydrogen-rich gas with low (≤ 0,8 vol.%) CH4 content and Н2 productivity ~3,1 l/(gcat · h) at 350 °C under ambient pressure using a reaction mixture (molar ratio): DME : O2 : N2 = 1 : 1 : 4 (DME : air = 1 : 5) at a flow rate 7 l/(gcat · h).
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Шумов, И. В., В. В. Антонова, Е. А. Боева, В. Т. Долгих, and О. А. Гребенчиков. "NEUROPROTECTIVE PROPERTIES OF KRYPTON IN PHOTO-INDUCED CEREBRAL INFARCTION IN RATS." Vestnik SurGU. Meditsina 16, no. 3 (2023): 89–96. http://dx.doi.org/10.35266/2304-9448-2023-3-89-96.
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The study aims to assess the effect of a two-hour inhalation with a krypton and oxygen mixture following the photo-induced cerebral infarction simulation on the manifestation of neurological deficits and the degree of brain injury in rats. The tests were conducted on male Wistar rats weighting 250 to 300 g (n = 20). Following photo-induced cerebral infarction simulation, the rodents underwent inhalation with a nitrogen and oxygen mixture N2 70%/O2 30% (group Nitrogen; n = 10) or a krypton and oxygen gas mixture Kr 70%/O2 30% (group Krypton; n = 10) for two hours. For the next 14 days, the rats were examined. On the 3rd, 7th, and 14th days, the authors performed a neurological test Limb placement, as well as euthanasia and brain removal for histological and mmunohistochemical examinations. It was determined that a two-hour inhalation with a krypton and oxygen gas mixture substantiated more prominent rehabilitation of rats’ neurological states by the seventh day, as well as increased the reparation and regeneration of their injured brains.
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Yang, Suo, Praise Noah Johnson, and Taaresh Sanjeev Taneja. "(Invited) Plasma-Assisted Ammonia Combustion and Flare Gas Reforming to Enhance Reactivity and Control Emission." ECS Meeting Abstracts MA2023-01, no. 20 (August 28, 2023): 1496. http://dx.doi.org/10.1149/ma2023-01201496mtgabs.
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Increasing emphasis on the de-carbonization of energy production has led researchers to consider carbon-free, renewable, and green fuels such as hydrogen (H2) and ammonia (NH3). While H2 suffers from the major challenges of production difficulties, transportation, and storage, NH3 is plagued with challenges of low flame speeds causing unstable flames, high autoignition temperatures resulting in longer ignition delays, narrow flammability limits, and higher levels of NOx emission. Among the different solutions to overcome these challenges of NH3 combustion, non-equilibrium plasma-based igniters are significant owing to the promotion of localized volumetric ignition kernel development by both thermal and chemical assistance. Computational investigation of plasma-assisted combustion of ammonia-air mixtures in constant volume and constant pressure reactors are conducted, to determine the impact of operating conditions on ignition delays and NOx emissions. A mechanism has been assembled in this work using well-validated plasma reactions of NH3 with O2 and N2, alongside plasma kinetics of air from the literature. Subsequently, the newly developed mechanism was used to investigate the plasma-assisted oxidation of NH3. In particular, the impact of the reduced electric field (E/N), equivalence ratio, pressure, pulse frequency, and energy density on the ignition delays and NOx emission were investigated. A Global Pathway-based Analysis algorithm for plasma-assisted systems (PGPA) is used to analyze the nanosecond pulsed nonequilibrium plasma-assisted combustion of NH3/air mixtures. Firstly, a faster ignition and lower production of NOx are observed in the case of plasma discharges compared to thermal energy deposition, owing to the enhanced production of OH radicals and the early reforming of NH3 to produce N2 and H2 with plasma, respectively. At lower reduced electric fields (E/N), PGPA analyses elucidated the significance of gas heating due to vibrational-translational cycles of NH3 and N2 on the increased reactivity of NH3/air mixtures as compared to ignition at a higher E/N. The fuel-lean mixture is observed to exhibit higher production of NOx than stoichiometric and fuel-rich mixtures, resulting from plasma chemistry involving oxygen radical and electronic excited states of N2. Higher rates of collisional quenching at higher pressures during the inter-pulse gaps are found to result in a lesser amount of electronically excited states of N2 and O2, resulting in lower production of air-bound NOx during the pulses. Complementing combustion enhancements, the study also considers the role of plasma-assisted systems in gas reforming, thereby imparting specific desired characteristics lacking in the original mixture. For instance, plasma-assisted reforming can be utilized to control emissions by reforming specific emission precursors or by improving the gas reactivity to promote clean combustion. Natural gas associated with oil wells and natural gas fields is a significant source of greenhouse gas emissions and airborne pollutants. Flaring/burning of the associated gas removes greenhouse gases like methane (CH4) and other hydrocarbons. Our study explores the possibility of enhancing the flaring of associated gas mixtures (C1 – C4 alkane mixture) using nanosecond pulsed non-equilibrium plasma discharges. A well-studied conventional combustion chemistry for small alkanes is coupled with the plasma kinetics of CH4, C2H6, C3H8, and N2, including electron-impact excitations, dissociations, and ionization reactions. The newly developed plasma-based flare gas chemistry is then utilized to investigate repetitively pulsed nonequilibrium plasma-assisted reforming and subsequent combustion of the flare gas mixture diluted with N2 at different conditions. The results indicate an enhanced production of H2 and C2H4 in the reformed gas mixture, owing to the electron-impact dissociations of alkanes and subsequent H-abstractions and recombination reactions, thereby resulting in a mixture of CH4, H2, C2H4, C2H2, and other unsaturated C3. The reformed mixture exhibits significantly high reactivity as exhibited by their increased flame speeds and shorter ignition delays. The reformed mixture is also observed to promote increased CH4 destruction levels and complete flaring, thereby reducing the emissions of CH4 and other hydrocarbons.
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Su, Yiru, Siyao Liu, and Xuechao Gao. "Impact of Impure Gas on CO2 Capture from Flue Gas Using Carbon Nanotubes: A Molecular Simulation Study." Molecules 27, no. 5 (March 1, 2022): 1627. http://dx.doi.org/10.3390/molecules27051627.
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We used a grand canonical Monte Carlo simulation to study the influence of impurities including water vapor, SO2, and O2 in the flue gas on the adsorption of CO2/N2 mixture in carbon nanotubes (CNTs) and carboxyl doped CNT arrays. In the presence of single impure gas, SO2 yielded the most inhibitions on CO2 adsorption, while the influence of water only occurred at low pressure limit (0.1 bar), where a one-dimensional chain of hydrogen-bonded molecules was formed. Further, O2 was found to hardly affect the adsorption and separation of CO2. With three impurities in flue gas, SO2 still played a major role to suppress the adsorption of CO2 by reducing the adsorption amount significantly. This was mainly because SO2 had a stronger interaction with carbon walls in comparison with CO2. The presence of three impurities in flue gas enhanced the adsorption complexity due to the interactions between different species. Modified by hydrophilic carboxyl groups, a large amount of H2O occupied the adsorption space outside the tube in the carbon nanotube arrays, and SO2 produced competitive adsorption for CO2 in the tube. Both of the two effects inhibited the adsorption of CO2, but improved the selectivity of CO2/N2, and the competition between the two determined the adsorption distribution of CO2 inside and outside the tube. In addition, it was found that (7, 7) CNT always maintained the best CO2/N2 adsorption and separation performance in the presence of impurity gas, for both the cases of single CNT and CNT array.
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Yang, Ming, Veena M. Bhopale, and Stephen R. Thom. "Separating the roles of nitrogen and oxygen in high pressure-induced blood-borne microparticle elevations, neutrophil activation, and vascular injury in mice." Journal of Applied Physiology 119, no. 3 (August 1, 2015): 219–22. http://dx.doi.org/10.1152/japplphysiol.00384.2015.
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An elevation in levels of circulating microparticles (MPs) due to high air pressure exposure and the associated inflammatory changes and vascular injury that occur with it may be due to oxidative stress. We hypothesized that these responses arise due to elevated partial pressures of N2 and not because of high-pressure O2. A comparison was made among high-pressure air, normoxic high-pressure N2, and high-pressure O2 in causing an elevation in circulating annexin V-positive MPs, neutrophil activation, and vascular injury by assessing the leakage of high-molecular-weight dextran in a murine model. After mice were exposed for 2 h to 790 kPa air, there were over 3-fold elevations in total circulating MPs as well as subgroups bearing Ly6G, CD41, Ter119, CD31, and CD142 surface proteins—evidence of neutrophil activation; platelet-neutrophil interaction; and vascular injury to brain, omentum, psoas, and skeletal muscles. Similar changes were found in mice exposed to high-pressure N2 using a gas mixture so that O2 partial pressure was the same as that of ambient air, whereas none of these changes occurred after exposures to 166 kPa O2, the same partial pressure that occurs during high-pressure air exposures. We conclude that N2 plays a central role in intra- and perivascular changes associated with exposure to high air pressure and that these responses appear to be a novel form of oxidative stress.
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Cheng, Chuchu, Fangjie Xu, Wenwen Shi, Qiaoyun Wang, and Caijin Huang. "Photocatalysis: A Possible Vital Contributor to the Evolution of the Prebiotic Atmosphere and the Warming of the Early Earth." Catalysts 13, no. 9 (September 20, 2023): 1310. http://dx.doi.org/10.3390/catal13091310.
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The evolution of the early atmosphere was driven by changes in its chemical composition, which involved the formation of some critical gases. In this study, we demonstrate that nitrous oxide (N2O) can be produced from Miller’s early atmosphere (a mixture of CH4, NH3, H2, and H2O) by way of photocatalysis. Both NH3 and H2O were indispensable for the production of N2O by photocatalysis. Different conditions related to seawater and reaction temperature are also explored. N2O has a strong greenhouse gas effect, which is more able to warm the Earth than other gases and offers a reasonable explanation for the faint young Sun paradox on the early Earth. Moreover, the decomposition of N2O into N2 and O2 can be boosted by soft irradiation, providing a possible and important origin of atmospheric O2 and N2. The occurrence of O2 propelled the evolution of the atmosphere from being fundamentally reducing to oxidizing. This work describes a possible vital contribution of photocatalysis to the evolution of the early atmosphere.
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Li, Xiao Hua, Xing Wei, Yi Xi Cai, Wen He Han, and Kang Hua Li. "Experimental Study on NO Pre-Oxidation in C3H6/NO/N2/O2 Mixture by Non-Thermal Plasma." Advanced Materials Research 712-715 (June 2013): 590–96. http://dx.doi.org/10.4028/www.scientific.net/amr.712-715.590.
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By using self-designed non-thermal plasma reactor, the influences of discharge power, initial concentration of C3H6 and O2 concentration on NO pro-oxidation in C3H6/NO/N2/O2 mixture were studied. The obtained results indicate that with the increasing of discharge power, NO2/NOx ratio grows firstly and then decreases after reaching a peak value, while NOx conversion efficiency and N2O concentration gradually rise. Increasing initial concentration of C3H6 or O2 concentration would help to enhance NO oxidation efficiency. With the same discharge power, NOx conversion efficiency grows with the increasing of C3H6 initial concentration while reduces with the increasing of O2 concentration. Controlling the concentration of C3H6 and O2 in exhaust gas can lead the NO2/NOx ratio to reach 50%, which is benefit to NOx conversion with SCR system.
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Marco de Lucas, María del Carmen, Franck Torrent, Gianni-Paolo Pillon, Pascal Berger, and Luc Lavisse. "Seeking the Oxidation Mechanism of Debris in the Fretting Wear of Titanium Functionalized by Surface Laser Treatments." Coatings 13, no. 6 (June 16, 2023): 1110. http://dx.doi.org/10.3390/coatings13061110.
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Surface laser treatment (SLT) using nanosecond IR lasers has been shown to improve the tribological behaviour of titanium. Here, we studied the fretting wear of SLT-functionalized pure titanium in a mixture of reactive gases O2 (20 vol.%) + N2 (80 vol.%). The contact geometry was a ball on a plane and the ball was made of bearing steel. The very small amplitude of relative displacement between reciprocating parts in fretting wear makes the evacuation of wear particles difficult. Moreover, the oxidation mechanism of the debris depends on the accessibility of the surrounding atmosphere to the tribological contact. This work focused in the analysis of debris generation and oxidation mechanisms, and sought to differentiate the role of oxygen forming part of the ambient O2 + N2 gas mixture from oxygen present in the surface layer of the SL-treated titanium. Before the fretting test, the surface of the commercially pure titanium plates was treated with a laser under a mixture of O2 + N2 gases with oxygen enriched in the 18O isotope. Then, the fretting tests were performed in regular air containing natural oxygen. Micro-Raman spectroscopy and ion beam analysis (IBA) techniques were used to analyse the TiO2 surface layers and fretting scars. Iron oxide particles were identified by Raman spectroscopy and IBA as the third body in the tribological contact. The spatial distribution of 18O, Ti, 16O and Fe in the fretting scars was studied by IBA. The analysis showed that the areas containing high concentrations of Fe displayed also high concentrations of 16O, but smaller concentrations of 18O and Ti. Therefore, it was concluded that tribological contact allows the oxidation of iron debris by its reaction with ambient air.
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Ikpe, A. E., and I. B. Owunna. "A 3D modelling of the in-cylinder combustion dynamics of two stroke internal combustion engine in its service condition." Nigerian Journal of Technology 39, no. 1 (April 3, 2020): 161–72. http://dx.doi.org/10.4314/njt.v39i1.18.
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In this study, a two stroke internal combustion engine was successfully modeled as a closed cycle with the intake, compression, expansion and exhaust processes considered in two strokes of the reciprocating piston. The in-cylinder combusted gases with respect to air-fuel mixture of 14.4:1 in the two stroke engine model were analyzed, showing the dynamics of the combusted gases, the flame pressure and temperature trajectories. It was observed that provided compression and expansion takes place at air-fuel mixture near ideal condition (14.7:1), the combusted gas temperature which occurred in the range of 293.92-3000.60 K is directly proportional to the cylinder gas pressure which occurred in the range of 60.76-80.20 bar. With a heat transfer coefficient of 581.236 W/m2K, the maximum temperature of the IC engine material was found to be 2367.56K at equilibrium and the maximum shear stress was found to be 176 x 102 MPa (1.76 x 105 bar). The 14.4:1 air-fuel mixture implies that 26% O2, 73% N2 and 1% trace gases are the in-cylinder air constituent that will react with 1 mole of hydrocarbon to form the combusted products of 96.2% CO2, 3.2% H2O and 0.6% N2. This will vary in conditions where the air-fuel mixture changes.
Keywords: Modelling, Gas dynamics, Two stroke, IC engine, Air-fuel mixture.
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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.
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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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Nowicki, P. T., N. B. Hansen, J. R. Hayes, J. A. Menke, and R. R. Miller. "Intestinal blood flow and O2 uptake during hypoxemia in the newborn piglet." American Journal of Physiology-Gastrointestinal and Liver Physiology 251, no. 1 (July 1, 1986): G19—G24. http://dx.doi.org/10.1152/ajpgi.1986.251.1.g19.
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Previous work has indicated that the neonatal intestinal circulation responds to hypoxemia with vasoconstriction and subsequent intestinal ischemia. This work was carried out in newborn lambs, a ruminant species, and may not be representative of all newborns. Therefore, we measured intestinal blood flow, vascular resistance, tissue O2 uptake, and cardiac output during normoxemia and varying degrees of hypoxemia in newborn piglets, a nonruminant species. Hypoxemia was induced by adding N2 gas to the inspired gas mixture, and measurements were obtained over a wide range of arterial O2 contents (2.2–15.6 ml O2 X dl-1). Intestinal blood flow increased in response to moderate hypoxemia and decreased in response to severe hypoxemia. The changes in intestinal blood flow were primarily due to change in intestinal vascular resistance, not cardiac output. Intestinal O2 was independent of arterial O2 content until the latter decreased below approximately 6.5 ml O2 X dl-1. These data indicate that the response of the neonatal intestinal circulation to hypoxemia is species specific and that the nonruminant neonatal intestine is capable of vasodilation in response to moderate hypoxemia.
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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.
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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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Alisoy, Hafiz Z., Ali Yesil, Murat Koseoglu, and Ibrahim Unal. "An approach for unipolar corona discharge in N2/O2 gas mixture by considering townsend conditions." Journal of Electrostatics 69, no. 4 (August 2011): 284–90. http://dx.doi.org/10.1016/j.elstat.2011.04.002.
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Lee, Jung-Kyu, Hyo-Chang Lee, and Chin-Wook Chung. "E–H mode transition in inductively coupled plasma using Ar, O2, N2, and mixture gas." Current Applied Physics 11, no. 5 (September 2011): S149—S153. http://dx.doi.org/10.1016/j.cap.2011.04.009.
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Wang, Yong, Danqing Huang, Jing Liu, Yaru Zhang, and Lian Zeng. "Alternative Environmentally Friendly Insulating Gases for SF6." Processes 7, no. 4 (April 15, 2019): 216. http://dx.doi.org/10.3390/pr7040216.
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Sulfur hexafluoride (SF6) shows excellent insulation performance as an insulating gas. It is suitable for various climate conditions due to its low boiling point (−64 °C). Therefore, it has been widely used in power grid equipment. However, its global warming potential (GWP) is 23,500 times higher than that of CO2. Thus, it is imperative to find an environmentally friendly insulating gas with excellent insulation performance, lower GWP, and which is harmless to equipment and workers to replace SF6. In this review, four possible alternatives, including perfluorocarbons, trifluoroiodomethane, perfluorinated ketones, and fluoronitrile are reviewed in terms of basic physicochemical properties, insulation properties, decomposition properties, and compatibility with metals. The influences of trace H2O or O2 on their insulation performances are also discussed. The insulation strengths of these insulating gases were comparable to or higher than that of SF6. The GWPs of these insulating gases were lower than that of SF6. Due to their relatively high boiling point, they should be used as a mixture with buffering gases with low boiling points. Based on these four characteristics, perfluorinated ketones (C5F10O and C6F12O) and fluoronitrile (C4F7N) could partially substitute SF6 in some electrical equipment. Finally, some future needs and perspectives of environmentally friendly insulating gases are addressed for further studies.
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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.
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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.
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Eves, Neil D., Stewart R. Petersen, and Richard L. Jones. "Effects of Helium and 40% O2 on Graded Exercise With Self-Contained Breathing Apparatus." Canadian Journal of Applied Physiology 28, no. 6 (December 1, 2003): 910–26. http://dx.doi.org/10.1139/h03-065.
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Maximal exercise performance is decreased when breathing from a self-contained breathing apparatus (SCBA), owing to a ventilatory limitation imposed by the increased expiratory resistance. To test the hypothesis that decreasing the density of the breathing gas would improve maximal exercise performance, we studied 15 men during four graded exercise tests with the SCBA. Participants breathed a different gas mixture during each test: normoxia (NOX; 21% O2, 79% N2), hyperoxia (HOX; 40% O2, 60% N2), normoxic helium (HE-OX; 21% O2, 79% He), and hyperoxic helium (HE-HOX; 40% O2, 60% He). Compared to NOX, power output at the ventilatory threshold and at maximal exercise significantly increased with both hyperoxic mixtures. Minute ventilation was increased at peak exercise with both helium mixtures, and maximal aerobic power ([Formula: see text]) was significantly increased by 12.9 ± 5.6%, 10.2 ± 6.3%, and 21.8 ± 5.6% with HOX, HE-OX, and HE-HOX, respectively. At peak exercise, the expired breathing resistance imposed by the SCBA was significantly decreased with both helium mixtures, and perceived respiratory distress was lower with HE-HOX. The results show that HE-OX improved maximal exercise performance by minimizing the ventilation limitation. The performance-enhancing effect of HOX may be explained by increased arterial oxygen content. Moreover, HE-HOX appeared to combine the effects of helium and hyperoxia on [Formula: see text]Key words:[Formula: see text] breathing resistance, ventilatory limitation, heliox, firefighting
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Day, Brian A., and Christopher E. Wilmer. "Genetic Algorithm Design of MOF-based Gas Sensor Arrays for CO2-in-Air Sensing." Sensors 20, no. 3 (February 10, 2020): 924. http://dx.doi.org/10.3390/s20030924.
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Gas sensor arrays, also known as electronic noses, leverage a diverse set of materials to identify the components of complex gas mixtures. Metal-organic frameworks (MOFs) have emerged as promising materials for electronic noses due to their high-surface areas and chemical as well as structural tunability. Using our recently reported genetic algorithm design approach, we examined a set of 50 MOFs and searched through over 1.125 × 1015 unique array combinations to identify optimal arrays for the detection of CO2 in air. We found that despite individual MOFs having lower selectivity for O2 or N2 relative to CO2, intelligently selecting the right combinations of MOFs enables accurate prediction of the concentrations of all components in the mixture (i.e., CO2, O2, N2). We also analyzed the physical properties of the elements in the arrays to develop an intuition for improving array design. Notably, we found that an array whose MOFs have diversity in their volumetric surface areas has improved sensing. Consistent with this observation, we found that the best arrays consistently had greater structural diversity (e.g., pore sizes, void fractions, and surface areas) than the worst arrays.