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Factors contributing to the oxygen concentration over the Qinghai-Tibetan Plateau and its contribution rate calculation

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Science China Earth Sciences 2024年第2期67卷 497-509页

作者： Peijun SHI Ying ZHANG Yanqiang CHEN Wenquan ZHU Xiaokang HU Heyi YANG Lu JIANG Yonggui MA Haiping TANG State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal UniversityBeijing100875China Key Laboratory of Environmental Change and Natural Disaster Ministry of EducationBeijing Normal UniversityBeijing100875China The Institute for Disaster Management and Reconstruction Sichuan UniversityChengdu610065China Academy of Plateau Science and Sustainability People’s Government of Qinghai Province&Beijing Normal UniversityXining810016China

A decline in atmospheric oxygen concentration is projected in the 21st century given the background of global *** Qinghai-Tibetan Plateau is located at a high altitude,and thus,it faces a hypoxia challenge;however,knowledge of the factors contributing to its atmospheric oxygen concentration is still ***,we conducted joint observations of ecosystem oxygen production and carbon sinks and near-surface atmospheric oxygen concentrations on the Qinghai-Tibetan Plateau and meteorological elements at Beijing Fangshan *** seasonal differences and statistical methods,we calculated the relative contribution rates of vegetation to changes in atmospheric oxygen *** results indicate that solar radiation,atmospheric humidity,and ecosystem oxygen consumption and production have a significant impact on the atmospheric oxygen concentration,and the impact shows temporal and spatial *** significantly impacts the oxygen concentration,with a contribution rate of 16.7%–24.5%,which is underestimated in existing *** findings provide important insights into the factors that influence atmospheric oxygen concentration and highlight the contribution of *** better understand the oxygen dynamics of the Qinghai-Tibetan Plateau,we recommend further field observations of soil respiration and vegetation photosynthesis to clarify the contributions of carbon storage,carbon sinks and other factors to the near-surface atmospheric oxygen concentration.

关键词： Qinghai-Tibetan Plateau oxygen concentration Relative contribution rate Air temperature Vegetation

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Effects of oxygen concentration and irradiation defects on the oxidation corrosion of body-centered-cubic iron surfaces:A first-principles study

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Chinese Physics B 2022年第8期31卷 566-577页

作者： Zhiqiang Ye Yawei Lei Jingdan Zhang Yange Zhang Xiangyan Li Yichun Xu Xuebang Wu C.S.Liu Ting Hao Zhiguang Wang Key Laboratory of Materials Physics Institute of Solid State PhysicsHFIPSChinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China School of Mechanical Engineering Suzhou University of Science and TechnologySuzhou 215009China Institute of Modern physics Chinese Academy of SciencesLanzhou 730000China

Oxidation corrosion of steels usually occurs in contact with the oxygen-contained environment, which is accelerated by high oxygen concentration and irradiation. The oxidation mechanism of steels is investigated by the adsorption/solution of oxygen atoms on/under body-centered-cubic(bcc) iron surfaces, and diffusion of oxygen atoms on the surface and in the near-surface region. Energetic results indicate that oxygen atoms prefer to adsorb at hollow and long-bridge positions on the Fe(100) and(110) surfaces, respectively. As the coverage of oxygen atoms increases, oxygen atoms would repel each other and gradually dissolve in the near-surface and bulk region. As vacancies exist, oxygen atoms are attracted by vacancies, especially in the near-surface and bulk region. Dynamic results indicate that the diffusion of O atoms on surfaces is easier than that into near-surface, which is affected by oxygen coverage and vacancies. Moreover, the effects of oxygen concentration and irradiation on oxygen density in the near-surface and bulk region are estimated by the Mc Lean’s model with a simple hypothesis.

关键词： oxidation corrosion oxygen concentration irradiation defects bcc-Fe surfaces first-principles study

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Effects of argon gas flow rate and guide shell on oxygen concentration in Czochralski silicon growth

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Rare Metals 2006年第1期25卷 7-10页

作者： REN Bingyan ZHAO Long ZHAO Xiuling WANG Huixian CAO Zhongqian ZHU Huimin FU Hongbo School of Material Science and Engineering Hebei University of Technology Tianjin 300130 China Hebei Ningjin Jinglong Semiconductor Factory Ningjin 055550 China Yunnan Semiconductor Device Factory Kunming 650033 China

φ200 mm silicon single crystals were grown in the φ450 mm hot zone of a Czochralski （CZ） furnace. By modifying the pattern and the velocity of the argon flow, the silicon single crystals with different oxygen concentrations were obtained. Through numerical simulation, the velocity of the argon gas flow was plotted for the first time. The experiment resuits were analyzed and the optimum condition of the argon flow with the lowest oxygen concentration was obtained.

关键词： inorganic non-metal material CZSi numerical simulation guide shell oxygen concentration

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Effects of oxygen concentration in Monocrystalline Silicon on Reverse Leakage Current of PIN Rectifier Diodes

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Journal of Wuhan University of Technology(Materials Science) 2021年第4期36卷 472-477页

作者： SUN Xinli GUO Hui ZHANG Yuming GUO Bingjian LI Xingpeng CAO Zhen State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology School of MicroelectronicsXidian UniversityXi'an 710071China Xi'an Zhongjing Semiconductor Materials Co. Ltd.Xi'an 710071China

The effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diodes were *** fabricated the PIN rectifier diodes with different initial oxygen concentrations,and analyzed the electrical properties,anisotropic preferred etching by means of optical microscopy,Fourier transform infrared spectroscopy and transmission electron *** is pointed out that the reverse leakage current increases exponentially with the increasing initial oxygen ***,we researched and analyzed the mechanism of the effects of initial oxygen concentration on the reverse leakage current of PIN rectifier *** is shown that the oxygen precipitations present in an "S" curve with increasing initial oxygen concentration after high temperature *** main reason is that the nucleation and growth of oxygen precipitation at high temperature induce bulk oxidation-induced defects (B-OSF),which are mainly dislocations,and a small amount of rod stacking *** density of B-OSF increases with the increasing initial oxygen *** existence of B-OSF has great effects on the reverse leakage current of PIN rectifier diode.

关键词： oxygen concentration PIN rectifier diode induced defect reverse leakage current

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Relationship between oxygen concentration, respiration and filtration rate in blue mussel Mytilus edulis

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Journal of Oceanology and Limnology 2018年第2期36卷 395-404页

作者： TANG Baojun Hans Ulrik RIISGARD Marine Biological Research Centre University of Southern Denmark Hindsholmvej 11 DK-5300 Kerteminde Denmark East China Sea Fisheries Research Institute Chinese Academy of Fishery Sciences Shanghai 200090 China

The large water-pumping and particle-capturing gills of the filter-feeding blue mussel Mytilus edulis are oversized for respiratory purposes. Consequently, the oxygen uptake rate of the mussel has been suggested to be rather insensitive to decreasing oxygen concentrations in the ambient water, since the diffusion rate of oxygen from water flowing through the mussel determines oxygen uptake. We tested this hypothesis by measuring the oxygen uptake in mussels exposed to various oxygen concentrations. These concentrations were established via N2-bubbling of the water in a respiration chamber with mussels fed algal cells to stimulate fully opening of the valves. It was found that mussels exposecl to oxygen concentrations decreasing from 9 to 2 mg O2/L resulted in a slow but significant reduction in the respiration rate, while the filtration rate remained high and constant. Thus, a decrease of oxygen concentration by 78% only resulted in a 25% decrease in respiration rate. However, at oxygen concentrations below 2 mg O2/L M. edulis responded by gradually closing its valves, resulting in a rapid decrease of filtration rate, concurrent with a rapid reduction of respiration rate. These observations indicated that M. edulis is no longer able to maintain its normal aerobic metabolism at oxygen concentration below 2 mg O2/L, and there seems to be an energy-saving mechanism in bivalve molluscs to strongly reduce their activity when exposed to low oxygen conditions.

关键词： Mytilus edulis filtration rate respiration rate oxygen concentration valve-opening degree

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Prediction of oxygen concentration and temperature distribution in loose coal based on BP neural network

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Mining Science and Technology 2009年第2期19卷 216-219页

作者： ZHANG Yong-jian WU Guo-guang XU Hong-feng MENG Xian-liang WANG Guang-you School of Chemical Engineering and Technology China University of Mining ＆ Technology Xuzhou Jiangsu 221008 China

An effective method for preventing spontaneous combustion of coal stockpiles on the ground is to control the air-flow in loose coal. In order to determine and predict accurately oxygen concentrations and temperatures within coal stockpiles, it is vital to obtain information of self-heating conditions and tendencies of spontaneous coal combustion. For laboratory conditions, we designed our own experimental equipment composed of a control-heating system, a coal column and an oxygen concentration and temperature monitoring system, for simulation of spontaneous combustion of block coal （13-25 mm） covered with fine coal （0-3 mm）. A BP artificial neural network （ANN） with 150 training samples was gradually established over the course of our experiment. Heating time, relative position of measuring points, the ratio of fine coal thickness, artificial density, voidage and activation energy were selected as input variables and oxygen concentration and temperature of coal column as output variables. Then our trained network was applied to predict the trend on the untried experimental data. The results show that the oxygen concentration in the coal column could be reduced below the minimum still able to induce spontaneous combustion of coal - 6% by covering the coal pile with fine coal, which would meet the requirement to prevent spontaneous combustion of coal stockpiles. Based on the prediction of this ANN, the average errors of oxygen concentration and temperature were respectively 0.5% and 7 ℃, which meet actual tolerances. The implementation of the method would provide a practical guide in understanding the course of self-heating and spontaneous combustion of coal stockpiles.

关键词： loose coal neural netwOrk spontaneous combustion of coal oxygen concentration temperature prediction

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Multiple Respiratory Gas Monitoring Causes Changes of Inspired oxygen concentration in Closed Anesthesia System

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Journal of Huazhong University of Science and Technology(Medical Sciences) 1997年第1期17卷 54-56页

作者：李士通汪正平曾邦雄刘俊杰 Department of Anesthesiology Xiehe Hospital Tongji Medical University Wuhan

Effect of multiple respiratory gas monitoring (MRGM ) on inspiredconcentration of oxygen in circult system during closed anesthesia was studied in 5l adult patients scheduled for abdominal surgery. Required flow rate of fresh oxygen (OFR), inspired oxygen concentration (FiO2 ) and oxygen saturation of pulse oximeter (SpO2) were measured continu0usly. Patients were equally divided into three groups at randorn, group C (no MRGN used ), group M, (using MRGM with its tail gas returned to circuit system), group M2 (using MRGM without tail gas returned ). The results revealed that during 180 min of closed anesthesia, OFR required in group C and M, were about 200-230 ml/min, and in group M, it was ab0ut 400 ml/min. In group C FiO2 decreased by about 10 % after 60 min of closed anesthesia (Poxygen than its sample gas drawn fr0m circuit system simuItaneously.

关键词： closed anesthesia oxygen concentration multiple respiratory gas monitor

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Nitrogen removal from wastewater and bacterial diversity in activated sludge at different COD/N ratios and dissolved oxygen concentrations

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Journal of Environmental Sciences 2012年第6期24卷 990-998页

作者： Magdalena Zielińska Katarzyna Bernat Agnieszka Cydzik-Kwiatkowska Joanna Sobolewska Irena Wojnowska-Baryla Department of Environmental Biotechnology University of Warmia and Mazury in OlsztynS oneczna St.45G10-709 OlsztynPoland

The impact of the organic carbon to nitrogen ratio （chemical oxygen demand （COD）/N） in wastewater and dissolved oxygen （DO） concentration on carbon and nitrogen removal efficiency, and total bacteria and ammonia-oxidizing bacteria （AOB） communities in activated sludge in constantly aerated sequencing batch reactors （SBRs） was determined. At DO of 0.5 and 1.5 mg O2/L during the aeration phase, the efficiency of ammonia oxidation exceeded 90%, with nitrates as the main product. Nitrification and denitrification achieved under the same operating conditions suggested the simultaneous course of these processes. The most effective nitrogen elimination （above 50%） was obtained at the COD/N ratio of 6.8 and DO of 0.5 mg O2/L. Total bacterial diversity was similar in all experimental series, however, for both COD/N ratios of 6.8 and 0.7, higher values were observed at DO of 0.5 mg O2/L. The diversity and abundance of AOB were higher in the reactors with the COD/N ratio of 0.7 in comparison with the reactors with the COD/N of 6.8. For both COD/N ratios applied, the AOB population was not affected by oxygen concentration. Amplicons with sequences indicating membership of the genus Nitrosospira were the determinants of variable technological conditions.

关键词： nitrogen removal activated sludge COD/N ratio oxygen concentration ammonia-oxidizing bacteria microbial diversity

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Experiment and Prediction of Fire Extinguishment with Water Mist in an Enclosed Room

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Journal of Thermal Science 2013年第1期22卷 71-79页

作者： Jianbo Zhao Lijun Yang School of Astronautics Beihang University

The correlation between oxygen concentration and fire temperature when fire was extinguished with water mist was theoretically studied. The Semenov theory was applied to analyze the critical condition when fire was extin- guished with water mist, from which the correlation could be obtained. The water mist experiments were carded out by varying the fire size, atomizer number, ceiling height, system pressure, and pre-burn time in an enclosed room. The oxygen concentration near the edge of the liquid pool and the fire temperature above the center of the liquid pool were measured. A comparison of the experimental data with the correlation was made under different conditions. The results showed that fire extinguishment was a stochastic process which could be affected by many factors. This theoretical model could predict the correlation between ftre temperature and oxygen concentration when fire was extinguished with water mist in an enclosed room and it can also be treated as a critical condition for fire extinguishment.

关键词： water mist fire temperature oxygen concentration

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Experimental study of an aircraft fuel tank inerting system

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Chinese Journal of Aeronautics 2015年第2期28卷 394-402页

作者： Cai Yan Bu Xueqin Lin Guiping Sun Bing Zeng Yu Li Zixuan School of Aeronautic Science and Engineering Beihang University

In this work, a simulated aircraft fuel tank inerting system has been successfully estab- lished based on a model tank. Experiments were conducted to investigate the influences of different operating parameters on the inerting effectiveness of the system, including flow rate of the inert gas （nitrogen-enriched air）, inert gas concentration, fuel load of the tank and different inerting approaches. The experimental results show that under the same operating conditions, the time span of a complete inerting process decreased as the flow rate of inert gas was increased; the time span using the inert gas with 5% oxygen concentration was much longer than that using pure nitrogen; when the fuel tank was inerted using the ullage washing approach, the time span increased as the fuel load was decreased; the ullage washing approach showed the best inerting performance when the time span of a complete inerting process was the evaluation criterion, but when the decrease of dissolved oxygen concentration in the fuel was also considered to characterize the inerting effective- ness, the approach of ullage washing and fuel scrubbing at the same time was the most effective.

关键词： Flow rate Fuel tank Inert oxygen concentration Time span Ullage

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