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Effect of 6H-SiC crystal growth shapes on thermo-elastic stress in the growing crystal

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International Journal of Minerals,Metallurgy and Materials 2012年第7期19卷 622-627页

作者： Yong-gui Shi Pei-yun Dai Jian-feng Yang Zhi-hao Jin hu-lin liu State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an 710049 China

The effect of 6H-SiC crystal growth shapes on the thermo-elastic stress distribution in the growing crystal was systematically in- vestigated by using a finite element method. The thermo-elastic stress distribution in the crystal with a flat growth shape was more homoge- neous than that in the crystals with concave and convex growth shapes, and the value of thermo-elasticity in the crystal with a fiat growth shape was also smaller than that in the two other types of crystals. The maximum values of thermo-elastic stress appeared at interfaces be- tween the crystal and the graphite lid. If the lid was of the same properties as 6H-SiC, the thermo-elastic stress would decrease in two orders of magnitude. Thus, to grow 6H-SiC single crystals of high quality, a transition layer of SiC formed by deposition or reaction is suggested; meanwhile the thermal field in the growth chamber should be adjusted to maintain the crystals with fiat growth shapes.

关键词： silicon carbide thermo-elasticity physical vapor transport single crystals crystal growth finite element method

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Association between antibiotic exposure and adverse outcomes of children and pregnant women: evidence from an umbrella review

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World Journal of Pediatrics 2023年第12期19卷 1139-1148页

作者： Ya Li lin-hu liu Zhong-Yu Jian Pu-Han Li Xi Jin Hong Li Kun-Jie Wang Department of Urology Institute of Urology(Laboratory of Reconstructive Urology)West China HospitalSichuan UniversityNo.37 Guo Xue AlleyWuhou DistrictChengduSichuanPeople's Republic of China West China Biomedical Big Data Center Sichuan UniversityChengduPeople's Republic of China

Background Antibiotics are widely prescribed among children and pregnant women,but their safety profile is *** study aimed to summarize and appraise current evidence for the potential impact of antibiotic exposure on pregnancy outcomes and children’s *** PubMed,Embase,Web of Science and the Cochrane Database of Systematic Reviews were searched from inception to June ***-analyses of any study design comparing the impact of antibiotic exposure with nonexposure among children,pregnant women and prepregnant women on adverse health outcomes of children and pregnancy were *** quality of evidence was assessed by a Measurement Tool to Assess Systematic Reviews 2(AMSTAR2)and the Grading of Recommendations,Assessment,Development and Evaluation(GRADE).Data were reanalyzed,and the credibility of the evidence was *** Out of 2956 studies identified,19 articles with 39 associations were *** 19 of the associations(48.72%)were statistically significant with a P value≤0.05,while only six were supported by highly suggestive *** with postnatal antibiotic exposure had a higher risk of developing asthma odds ratio(OR):1.95,95%confidence interval(CI):1.76–2.17,wheezing(OR:1.81,95%CI 1.65–1.97)and allergic rhinoconjunctivitis(OR:1.66,95%CI 1.51–1.83),with prediction intervals excluding the *** assessed by both AMSTAR2 and GRADE of included meta-analyses were very low in *** Antibiotic exposure in early life was associated with children’s long-term health,especially in cases of allergic *** exposure might also influence children’s health in some aspects but requires more high-quality *** adverse effects of antibiotics on pregnancy outcomes were not observed in our *** with higher quality and better quantification of antibiotic exposure are needed in the future.

关键词： Antibiotic exposure Gut microbiome Prenatal exposure Postnatal exposure Umbrella review

Development of a net ozone production rate detection system based on dual-channel cavity ring-down spectroscopy

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Journal of Environmental Sciences 2025年第3期149卷 419-430页

作者： Jinzhao Tong Renzhi hu Changjin hu Xiaoyan liu Haotian Cai Chuan lin liujun Zhong JiaweiWang Pinhua Xie School of Environmental Science and Optoelectronic Technology University of Science and Technology of ChinaHefei 230026China Anhui Institute of Optics and Fine Mechanics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China School of Pharmacy Anhui Medical UniversityHefei 230032China

A novel system for measuring net photochemical ozone production rates in the atmosphere based on cavity ring-down spectroscopy(OPR-CRDS)was *** system consists of two chambers(a reaction chamber and a reference chamber)and a dual-channel O_(x)-CRDS *** minimize the wall loss of O_(x)in the chambers,the inner surfaces of both chambers are coated with Teflon *** performance of the OPR-CRDS system was *** was found that even though the photolysis frequency(J value)decreased by 10%,the decrease in the P(O_(3))caused by the ultraviolet-blocking film coating was less than 3%.The two chambers had a good consistency in the mean residence time and the measurement of NO_(2)and O_(x)under the condition of no *** detection limit of the OPR-CRDS was determined to be 0.20 ppbv/*** further verify the accuracy of the system,the direct measurement values of the OPR-CRDS systemwere comparedwith the calculation results based on radical(OH,HO_(2),and RO_(2))reactions,and a good correlation was obtained between the measured and calculated ***,the developed instrument was applied to obtain the comprehensive field observations at an urban site in the Yangtze River Delta(China)for 40 days,the time series and change characteristics of the P(O_(3))were obtained directly,and the good environmental adaptability and stability of the OPR-CRDS system were *** is expected that the new instrument will be beneficial to investigations of the relationship between P(O_(3))and its precursors.

关键词： Ozone Net photochemical production rate CRDS Atmospheric chemistry

Aging behavior of large area MCP–PMT

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Nuclear Science and Techniques 2016年第2期27卷 136-140页

作者： Wen-Wen Wang Sen Qian Ming Qi Jing-Kai Xia Ya-Ping Cheng Zhe Ning Yue-Kun Heng Shu-lin liu Shu-Guang Si Jian-Ning Sun Dong Li Xing-Chao Wang Guo-Rui huang Jing-Shou Tian Yong-lin Wei hu-lin liu Wei-hua Li Xing Wang Li-Wei Xin Nanjing University Nanjing 210093 China State Key Laboratory of Particle Detection and Electronics(Institute of High Energy Physics CAS) Beijing 100049China Institute of High Energy Physics Chinese Academy of Science Beijing 100049 China University of Chinese Academy of Sciences Beijing China Nanjing North Night Vision Tech. Ltd. Nanjing 211106China Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi'an 710068 China

The Institute of High Energy Physics, Chinese Academy of Sciences have designed a new type of photomultiplier tube(PMT) based on microchannel plates(MCPs) with large area photocathode, known as large area microchannel plate photomultiplier tube(MCP–PMT). The aging characteristics of the large area MCP–PMTs are different from dynode PMTs and small proximity-focus MCP–PMT. In this work, a prototype large area MCP–PMT was aged by operating with nearly 1000 photoelectrons per pulse for 3 months, and aging process of the MCP–PMT was discussed based on the aging curve.

关键词： MCP-PMT 面积老化行为光电倍增管高能物理研究所微通道板中国科学院近贴聚焦

维普期刊数据库

Crystal Structure of a Novel Phosphorane (C_(30H27N3O12P-4) with Three P-P Bonds

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Chinese Journal of Structural Chemistry 2000年第4期19卷 275-280页

作者： WANG Wen hu ② WENG lin Hong liu Lun Zu (State Key Laboratory of Elemento Organic Chemistry, Institute of Elemento Organic Chemistry, Nankai University, Tianjin 300071, China) 南开大学元素有机化学国家重点实验室天津 30 0 0 71

The first phosphorane 3, C 30H 27N 3O 12P 4, M r =745.43, bearing three P-P bonds, was synthesized and its crystal structure was determined by X ray diffraction method. The crystal data are as follows: colorless crystals, orthorhombic, space group P2 12 12 1, a=9.4387(1), b=18.424(2), c=19.358(2) , V=3366.57(7)  3, D c =1.471Mg/m 3, λ (Mo Kα )=0.71073 , μ (Mo Kα )=0.291mm -1, F(000)=1536, Z =4. The structure was refined to R =0.0598 and wR(F 2 )=0.0758 for 5946 observed reflections [ I>2σ(I )]. The geometry of the P(4) atom is pyramidal, whereas the coordination geometry around the P(1), P(2) and P(3) atoms is a strongly distorted trigonal bipyramid.

关键词： phosphorane P-P bond pyramid trigonal bipyramid

Nitrogen-cycling processes under long-term compound heavy metal(loids)pressure around a gold mine:Stimulation of nitrite reduction

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Journal of Environmental Sciences 2025年第1期147卷 571-581页

作者： Xuesong hu Xiaoxia liu Shuo Zhang Caihong Yu School of Chemical&Environmental Engineering China University of Mining and Technology(Beijing)Beijing 100083China Beijing Cultivated Land Construction and Protection Center Beijing 100020China

Mining and tailings deposition can cause serious heavy metal(loids)pollution to the surrounding soil *** microorganisms adapt their metabolism to such conditions,driving alterations in soil *** study aims to elucidate the response patterns of nitrogen-cycling microorganisms under long-term heavy metal(loids)*** results showed that the diversity and abundance of nitrogen-cyclingmicroorganisms showed negative feedback to heavy metal(loids)*** microorganisms were shown to be the dominant microorganisms with over 60%of relative abundance and a complex community structure including 27 ***,the key bacterial species in the denitrification process were calculated using a random forest model,where the top three key species(Pseudomonas stutzei,Sphingobium japonicum and Leifsonia rubra)were found to play a prominent role in nitrite *** gene analysis and qPCR revealed that nirK,which is involved in nitrite reduction,significantly accumulated in the most metal-rich soil with the increase of absolute abundance of 63.86%.The experimental results confirmed that the activity of nitrite reductase(Nir)encoded by nirK in the soil was increased at high concentrations of heavy metal(loids).Partial least squares-path model identified three potential modes of nitrite reduction processes being stimulated by heavy metal(loids),the most prominent of which contributed to enhanced nirK abundance and soil Nir activity through positive stimulation of key *** results provide new insights and preliminary evidence on the stimulation of nitrite reduction processes by heavy metal(loids).

关键词： N cycle Nitrite reduction Nitrite reductase Metagenome Key species

New progresses of fine-grained sediment gravity-flow deposits and their importance for unconventional shale oil and gas plays

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Petroleum Science 2025年第1期22卷 1-15页

作者： Tian Yang Ying-lin liu State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Chengdu University of Technology) Institute of Sedimentary Geology Key Laboratory of Deep-time Geography and Environment Reconstruction and Applications of Ministry of Natural Resources Chengdu University of Technology

Fine-grained sediments are widely distributed and constitute the most abundant component in sedimentary systems, thus the research on their genesis and distribution is of great significance. In recent years, fine-grained sediment gravity-flows(FGSGF) have been recognized as an important transportation and depositional mechanism for accumulating thick successions of fine-grained sediments. Through a comprehensive review and synthesis of global research on FGSGF deposition, the characteristics,depositional mechanisms, and distribution patterns of fine-grained sediment gravity-flow deposits(FGSGFD) are discussed, and future research prospects are clarified. In addition to the traditionally recognized low-density turbidity current and muddy debris flow, wave-enhanced gravity flow, lowdensity muddy hyperpycnal flow, and hypopycnal plumes can all form widely distributed FGSGFD. At the same time, the evolution of FGSGF during transportation can result in transitional and hybrid gravityflow deposits. The combination of multiple triggering mechanisms promotes the widespread development of FGSGFD, without temporal and spatial limitations. Different types and concentrations of clay minerals, organic matters, and organo-clay complexes are the keys to controlling the flow transformation of FGSGF from low-concentration turbidity currents to high-concentration muddy debris flows. Further study is needed on the interaction mechanism of FGSGF caused by different initiations, the evolution of FGSGF with the effect of organic-inorganic synergy, and the controlling factors of the distribution patterns of FGSGFD. The study of FGSGFD can shed some new light on the formation of widely developed thin-bedded siltstones within shales. At the same time, these insights may broaden the exploration scope of shale oil and gas, which have important geological significances for unconventional shale oil and gas.

关键词： Fine-grained sediment gravity-flow Depositional mechanism Transportation and evolution Distribution pattern Shale oil and gas

Soil colloids can significantly enhance spreading of polybromodiphenyl ethers in groundwater by serving as an effective carrier

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Journal of Environmental Sciences 2025年第1期147卷 93-100页

作者： lin Duan Min Li Jiameng liu Wei Chen College of Environmental Science and Engineering Ministry of Education Key Laboratory of Pollution Processes and Environmental CriteriaTianjin Key Laboratory of Environmental Remediation and Pollution ControlNankai UniversityTianjin 300350China

Polybromodiphenyl ethers(PBDEs),the widely used flame retardants,are common contaminants in surface soils at e-waste recycling *** association of PBDEs with soil colloids has been observed,indicating the potential risk to groundwater due to colloid-facilitated ***,the extent to which soil colloidsmay enhance the spreading of PBDEs in groundwater is largely ***,we report the co-transport of decabromodiphenyl ester(BDE-209)and soil colloids in saturated porous *** colloids released froma soil sample collected at an e-waste recycling site in Tianjin,China,contain high concentration of PBDEs,with BDE-209 being the most abundant conger(320±30 mg/kg).The colloids exhibit relatively high mobility in saturated sand columns,under conditions commonly observed in groundwater ***,under all the tested conditions(i.e.,varying flow velocity,pH,ionic species and ionic strength),the mass of eluted BDE-209 correlates linearly with that of eluted soil colloids,even though the mobility of the colloids varies markedly depending on the specific hydrodynamic and solution chemistry conditions ***,the mass of BDE-209 retained in the columns also correlates strongly with themass of retained ***,the PBDEs remain bound to soil colloids during transport in porous *** in this study indicate that soil colloidsmay significantly promote the transport of PBDEs in groundwater by serving as an effective *** might be the reason why the highly insoluble and adsorptive PBDEs are found in groundwater at some PBDE-contaminated sites.

关键词： Polybromodiphenyl ethers Soil colloids E-waste recycling sites Groundwater Facilitated transport

Improving Multi-task GNNs for Molecular Property Prediction via Missing Label Imputation

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Machine Intelligence Research 2025年第1期22卷 131-144页

作者： Fenyu hu Dingshuo Chen Qiang liu Shu Wu University of Chinese Academy of Sciences Beijing100190China Center for Research on Intelligent Perception and Computing State Key Laboratory of Multimodal Artificial Intelligence SystemsInstitute of AutomationChinese Academy of SciencesBeijing100190China

The prediction of molecular properties is a fundamental task in the field of drug ***,graph neural networks(GNNs)have been gaining prominence in this *** a molecule tends to have multiple correlated properties,there is a great need to develop the multi-task learning ability of ***,limited by expensive and time-consuming human annotations,collecting complete labels for each task is *** a result,most existing benchmarks involve many missing labels in training data,and the performance of GNNs is impaired due to the lack of sufficient supervision *** overcome this obstacle,we propose to improve multi-task molecular property prediction by missing label ***,a bipartite graph is first introduced to model the molecule-task co-occurrence ***,the imputation of missing labels is transformed into predicting missing edges on this bipartite *** predict the missing edges,a graph neural network is devised,which can learn the complex molecule-task co-occurrence *** that,we select reliable pseudo labels according to the uncertainty of the prediction *** with enough and reliable supervision information,our approach achieves state-of-the-art performance on a variety of real-world datasets.

关键词： Graph classification imbalance learning prediction bias mixture of experts multiview representations