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Formation estimation and evolution mechanism of the pressure arch for non-circular tunnels under asymmetrical stress field

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Science China(Technological Sciences) 2024年第9期67卷 2919-2938页

作者： SUN ZhenYu ZHANG DingLi xu tong CHEN xu Key Laboratory for Urban Underground Engineering of Ministry of Education Beijing Jiaotong UniversityBeijing 100044China

The tunneling-induced stress redistribution is dependent on the tunnel shape and the in-situ stress field, and the previous arch characterization method based on the circumferential or maximum principal stresses is only suitable for the circular tunnels under the hydrostatic stress field. In this study, a unified characterization method of the pressure arch for non-circular tunnels under the arbitrary stress field is proposed. By comparing the variations of compressive stress in different directions due to excavation, the ratio of the most significant increase in compressive stress is presented to characterize the arch effect, and the corresponding numerical algorithm is given. Since the proposed method takes the stress element as the basic analytical model, it can be easily applied to various complex excavation situations. Thereafter, combined with the established folding catastrophic model, an objective and unified quantitative method of the pressure arch boundaries is given. Using the proposed method, the longitudinal evolution of the pressure arch is analyzed. According to the expansion rate of the arch boundaries, three evolution stages including the initial formation, rapid expansion and stabilization are categorized. Parametric studies are conducted to illustrate the effect of ground properties and support stiffness on the pressure arch formation. It is found that the ground strength parameters and burial depth affect the arch range at a decreasing rate, while they have little effect on the arch shape. The lateral pressure coefficient has a significant effect on both the shape and range of the pressure arch. Increasing the support stiffness helps reduce the pressure arch range with a decreasing rate, while the synchronous variation of the elastic moduli of the surrounding rock and support does not affect the arch range under a certain relative elastic modulus. Finally, field monitoring is conducted to validate the proposed method in actual support design.

关键词： pressure arch stress redistribution numerical simulation quantitative characterization longitudinal evolution parametric study

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Crystal facet-dependent CO_(2) cycloaddition to epoxides over ZnO catalysts

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Frontiers of Chemical Science and Engineering 2024年第5期18卷 49-59页

作者： Yongjian Wei Ying Li Yunfei xu Yinghui Sun tong xu Haiou Liang Jie Bai Inner Mongolia Key Laboratory of Industrial Catalysis Hohhot 010051China College of Chemical Engineering Inner Mongolia University of TechnologyHohhot 010051China

With regard to green chemistry and sustainable development,the fixation of CO_(2) into epoxides to form cyclic carbonates is an attractive and promising pathway for CO_(2) *** oxides,renowned as promising eco-friendly catalysts for industrial production,are often undervalued in terms of their impact on the CO_(2)addition *** this work,we successfully developed ZnO nanoplates with(002)surfaces and ZnO nanorods with(100)surfaces via morphology-oriented regulation to explore the effect of crystal faces on CO_(2) *** quantitative data obtained from electron paramagnetic resonance spectroscopy indicated that the concentration of oxygen vacancies on the ZnO nanoplate surfaces was more than twice that on the ZnO nanorod *** functional theory calculations suggested that the(002)surfaces have lower adsorption energies for CO_(2) and epichlorohydrin than the(100)*** a result,the yield of cyclochloropropene carbonate on the ZnO nanoplates(64.7%)was much greater than that on the ZnO nanorods(42.3%).Further evaluation of the reused catalysts revealed that the decrease in the oxygen vacancy concentration was the primary factor contributing to the decrease in catalytic *** on these findings,a possible catalytic mechanism for CO_(2) cycloaddition with epichlorohydrin was *** work provides a new idea for the controllable preparation of high-performance ZnO catalysts for the synthesis of cyclic carbonates from CO_(2) and epoxides.

关键词： carbon dioxide cycloaddition zinc oxide crystal face oxygen vacancy

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Prediction model on hydrolysis kinetics of phthalate monoester:A density functional theory study

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Journal of Environmental Sciences 2024年第1期135卷 51-58页

作者： tong xu Jingwen Chen Deming Xia Weihao Tang Jiansheng Cui Chun Liu Shuangjiang Li College of Environmental Science and Engineering Hebei University of Science and TechnologyShijiazhuang 050000China Key Laboratory of Industrial Ecology and Environmental Engineering(Ministry of Education) School of Environmental Science and TechnologyDalian University of TechnologyDalian 116024China National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and ManagementInstitute of Eco-environmental and Soil SciencesGuangdong Academy of SciencesGuangzhou 510650China

As primary degradation products of phthalate esters,phthalate monoesters(MPEs)have been widely detected in various aquatic environments and drawn growing toxicological *** kinetics that is of importance for assessing environmental persistence of chemicals remain elusive for ***,kinetics of base-catalyzed and neutral hydrolysis for 18 MPEs with different leaving groups was investigated by density functional theory *** indicate that MPEs with leaving groups having p Kaof<10 prefer dissociative transition *** are more persistent than their parents,and their hydrolysis half-lives were calculated to vary from 3.4 min to 79.2 years(p H=7–9).A quantitative structure-activity relationship model was developed for predicting the hydrolysis kinetics *** was found that p Kaof the leaving groups and electronegativity of the MPEs are key factors determining the hydrolysis *** work may lay a theoretical foundation for better understanding the chemical process that governs MPE persistence in aquatic environments.

关键词： Phthalate monoesters Phthalate esters Hydrolysis Density functional theory Quantitative structure-activity relationship

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Enhanced High-Temperature Energy Storage Performance of All-Organic Composite Dielectric via Constructing Fiber-Re in forced Structure

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Energy & Environmental Materials 2024年第2期7卷 299-307页

作者： Mengjia Feng Yu Feng Changhai Zhang Tiandong Zhang xu tong Qiang Gao Qingguo Chen Qingguo Chi Key Laboratory of Engineering Dielectrics and Its Application Ministry of EducationHarbin University of Science and TechnologyHarbin 150080China School of Electrical and Electronic Engineering Harbin University of Science and TechnologyHarbin 150080China

Optimizing the high-temperature energy storage characteristics of energy storage dielectrics is of great significance for the development of pulsed power devices and power control *** a polymer with a higher glass transition temperature(T_(g))as the matrix is one of the effective ways to increase the upper limit of the polymer operating ***,current high-T_(g)polymers have limitations,and it is difficult to meet the demand for high-temperature energy storage dielectrics with only one *** example,polyetherimide has high-energy storage efficiency,but low breakdown strength at high *** has high corona resistance,but low high-temperature energy storage *** this work,combining the advantages of two polymer,a novel high-T_(g)polymer fiber-reinforced microstructure is *** is designed as extremely fine fibers distributed in the composite dielectric,which will facilitate the reduction of high-temperature conductivity loss for *** the same time,due to the high-temperature resistance and corona resistance of polyimide,the high-temperature breakdown strength of the composite dielectric is *** the polyimide content with the best high-temperature energy storage characteristics is determined,molecular semiconductors(ITIC)are blended into the polyimide fibers to further improve the high-temperature ***,excellent high-temperature energy storage properties are *** 0.25 vol%ITIC-polyimide/polyetherimide composite exhibits high-energy density and high discharge efficiency at 150℃(2.9 J cm^(-3),90%)and 180℃(2.16 J cm^(-3),90%).This work provides a scalable design idea for high-performance all-organic high-temperature energy storage dielectrics.

关键词： all-organic energy storage density high-temperature high-temperature breakdown strength

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Spatio-Temporal Characteristics of Heavy Precipitation Forecasts from ECMWF in Eastern China

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Journal of Tropical Meteorology 2024年第1期30卷 29-41页

作者：徐同谭燕顾问 Shanghai Typhoon Institute and Key Laboratory of Numerical Modeling for Tropical Cyclone of China Meteorological AdministrationShanghai 200030 China State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100080 China Shanghai Ecological Forecasting and Remote Sensing Center Shanghai 200030 China

This study examines the spatio-temporal characteristics of heavy precipitation forecasts in eastern China from the European Centre for Medium-Range Weather Forecasts(ECMWF) using the time-domain version of the Method for Object-based Diagnostic Evaluation(MODE-TD). A total of 23 heavy rainfall cases occurring between 2018 and 2021 are selected for analysis. Using Typhoon “Rumbia” as a case study, the paper illustrates how the MODE-TD method assesses the overall simulation capability of models for the life history of precipitation systems. The results of multiple tests with different parameter configurations reveal that the model underestimates the number of objects’ forecasted precipitation tracks, particularly at smaller radii. Additionally, the analysis based on centroid offset and area ratio tests for different classified precipitation objects indicates that the model performs better in predicting large-area, fast-moving, and longlifespan precipitation objects. Conversely, it tends to have less accurate predictions for small-area, slow-moving, and shortlifespan precipitation objects. In terms of temporal characteristics, the model overestimates the forecasted movement speed for precipitation objects with small-area, slow movement, or both long and short lifespans while underestimating it for precipitation with fast movement. In terms of temporal characteristics, the model tends to overestimate the forecasted movement speed for precipitation objects with small-area, slow movement, or both long and short lifespans while underestimating it for precipitation with fast movement. Overall, the model provides more accurate predictions for the duration and dissipation of precipitation objects with large-area or long-lifespan(such as typhoon precipitation) while having large prediction errors for precipitation objects with small-area or short-lifespan. Furthermore, the model’s simulation results regarding the generation of precipitation objects show that it performs relati

关键词： MODE-TD ECMWF heavy precipitation Eastern China

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Establishment of microneurovascular units in alginate hydrogel microspheres to reveal the anti-hypoxic effect of salidroside

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Journal of Pharmaceutical Analysis 2024年第6期14卷 926-929页

作者： Shiyu Chen Yuxuan Li Yingrui Zhang Hongren Yao tong xu Yi Zhang Jin-Ming Lin Xian-Li Meng State Key Laboratory of Southwestern Chinese Medicine Resources Innovative Institute of Chinese Medicine and PharmacyChengdu University of Traditional Chinese MedicineChengdu611137China Beijing Key Laboratory of Microanalytical Methods and Instrumentation Department of ChemistryKey Laboratory of Bioorganic Phosphorus Chemistry&Chemical Biology(Ministry of Education)Tsinghua UniversityBeijing100084China School of Ethnic Medicine Chengdu University of Traditional Chinese MedicineChengdu611137China

Microneurovascular units(mNVUs),comprising neurons,micro-glia,and blood-brain barrier(BBB)endothelial cells,are pivotal to the central nervous system and are associated with cerebral hypoxia and brain *** hypoxia triggers microglial overactivity,causing inflammation,neuronal injury,and disruption of the BBB[1].Salidroside(Sal),a key compound in Tibetan medicine Rhodiola crenulata,mitigates hypoxia-induced metabolic disorders and neuronal damage by preserving mitochondrial function[2].

关键词： injuries preserving Tibetan

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Spatio-temporal evolution and topographic gradient effect of land use and ecosystem service value in the Lhasa River Basin

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Journal of Mountain Science 2024年第6期21卷 2059-2074页

作者： ZHOU Jianwei FENG Bin WU Hua xu tong CHEN Linna ZHAO Xinyong GUO Qiyun LI Jiatong ZHANG Chenguang ZHU Kangcheng KONG Yuzhong School of Ecology and Environment Tibet UniversityLhasa 850000China School of Engineering Tibet UniversityLhasa 850000China Joint Laboratory of Plateau Surface Remote Sensing Tibet UniversityLhasa 850000China

The Lhasa River Basin forms an essential human settlement area in the southern part of the Qinghai-Tibet *** study employed ecosystem service value(ESV)evaluation model,terrain gradient grading,and Geodetector to analyze land use and ESV in the Lhasa River Basin from 1985 to *** findings reveal that:(1)From 1985 to 2020,grassland was the dominant land *** was a trend of grassland reduction and the expansion of other land types.(2)ESV has increased over the research period(with a total increase of 0.84%),with higher values in the southeast and lower values in the *** contributed the most to ESV,and climate regulation and hydrological regulation were the ecosystem services that contribute the most to ESV.(3)Natural factors like NDVI and altitude,as well as economic factors like population density and distance from roads,influenced the spatial differentiation of ESV,the explanatory power of NDVI reached up to *** interaction between factors had a greater impact than individual *** research results can provide theoretical support for national spatial planning and ecological environment protection in the Lhasa River Basin and other similar areas.

关键词： Ecosystem services value Land use Terrain gradient effect Lhasa River Basin Driving factors

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Prevalence and clinical impact of sarcopenia in liver transplant recipients:A meta-analysis

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World Journal of Gastroenterology 2024年第8期30卷 956-968页

作者： Min-Jie Jiang Mu-Chen Wu Zhong-Hui Duan Jing Wu Xiao-tong xu Juan Li Qing-Hua Meng Department of Hepatology Beijing You-An HospitalCapital Medical UniversityBeijing 100069China Department of Emergency Beijing You-An HospitalCapital Medical UniversityBeijing 100069China

BACKGROUND The prevalence of sarcopenia in patients undergoing liver transplantation(LT)remains to be determined partly because of different diagnostic *** has recently been recognized as a new prognostic factor for predicting outcomes in LT *** To estimate the prevalence of sarcopenia and evaluate its clinical effect on LT *** This systematic search was conducted in PubMed,Web of Science,Embase,and Cochrane Library for original English-language articles that investigated the prevalence and influence of sarcopenia in patients undergoing LT from database inception to November 30,*** studies of the definition of sarcopenia that estimate sarcopenia prevalence and evaluate its effect on clinical outcomes and the risk of mortality were *** Twenty-five studies involving 7760 patients undergoing LT were *** pooled prevalence of sarcopenia in patients undergoing LT was 40.7%[95%confidence intervals(95%CI):32.1-49.6].The 1-,3-,and 5-year cumulative probab-ilities of post-LT survival in patients with preoperative sarcopenia were all lower than those without sarcopenia(P<0.05).Sarcopenia was associated with an increased risk of post-LT mortality in patients undergoing LT(adjusted hazard ratio:1.58;95%CI:1.21-2.07).Patients with preoperative sarcopenia had a longer intensive care unit stay,a high risk ratio of sepsis,and serious post-LT complications than those without *** Sarcopenia is prevalent in a substantial proportion of patients undergoing LT and is strongly and independently associated with higher a risk of mortality risk.

关键词： Sarcopenia Liver transplantation Mortality Clinical outcomes

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漏洞自动修复研究综述

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软件学报 2024年第1期35卷 136-158页

作者：徐同同刘逵夏鑫华为公司软件工程应用技术实验室浙江杭州310007

软件漏洞是计算机软件系统安全方面的缺陷,给现代软件及其应用数据的完整性、安全性和可靠性带来巨大威胁.人工治理漏洞费时且易错,为了更好应对漏洞治理挑战,研究者提出多种自动化漏洞治理方案,其中漏洞自动修复方法近来得到研究者广... 详细信息

软件漏洞是计算机软件系统安全方面的缺陷,给现代软件及其应用数据的完整性、安全性和可靠性带来巨大威胁.人工治理漏洞费时且易错,为了更好应对漏洞治理挑战,研究者提出多种自动化漏洞治理方案,其中漏洞自动修复方法近来得到研究者广泛关注.漏洞自动修复技术旨在辅助开发人员修复漏洞,涵盖漏洞根因定位、补丁生成、补丁验证等功能.现有工作缺乏对漏洞修复技术系统性的分类与讨论,为了促进漏洞修复技术发展,加深研究人员对漏洞修复问题的认知理解,对现有漏洞修复方法技术的理论、实践、适用场景和优缺点进行全面洞察,并撰写了漏洞自动修复技术的研究综述.主要内容包括:(1)按照修复漏洞类型不同整理归纳特定类型漏洞的修复方法以及通用类型漏洞的修复方法;(2)按照所采用的技术原理将不同修复方法进行分类与总结;(3)归纳漏洞修复主要挑战;(4)展望漏洞修复未来发展方向.

关键词：软件漏洞漏洞自动修复漏洞分析漏洞定位

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Functional predictability of universal gene circuits in diverse microbial hosts

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Quantitative Biology 2024年第2期12卷 129-140页

作者： Chenrui Qin tong xu xuejin Zhao Yeqing Zong Haoqian M.Zhang Chunbo Lou Qi Ouyang Long Qian Peking-Tsinghua Joint Center for Life Sciences Peking UniversityBeijingChina CAS Key Laboratory of Microbial Physiological and Metabolic Engineering Institute of MicrobiologyChinese Academy of SciencesBeijingChina Bluepha Co. LtdBeijingChina Center for Cell and Gene Circuit Design CAS Key Laboratory of Quantitative Engineering BiologyGuangdong Provincial Key Laboratory of Synthetic GenomicsShenzhen Key Laboratory of Synthetic GenomicsShenzhen Institute of Synthetic BiologyShenzhen Institutes of Advanced TechnologyChinese Academy of SciencesShenzhenChina Center for Quantitative Biology Academy for Advanced Interdisciplinary StudiesPeking UniversityBeijingChina

Although the principles of synthetic biology were initially established in model bacteria,microbial producers,extremophiles and gut microbes have now emerged as valuable prokaryotic chassis for biological *** the host range in which designed circuits can function reliably and predictably presents a major challenge for the concept of synthetic biology to *** this work,we systematically characterized the cross-species universality of two transcriptional regulatory modules—the T7 RNA polymerase activator module and the repressors module—in three non-model *** found striking linear relationships in circuit activities among different organisms for both *** model fitting revealed host non-specific parameters defining the universality of both ***,a genetic NOT gate and a band-pass filter circuit were constructed from these modules and tested in non-model *** models employing host non-specific parameters were successful in quantitatively predicting circuit behaviors,underscoring the potential of universal biological parts and predictive modeling in synthetic bioengineering.

关键词： circuit predictability host-independent genetic circuits host-nonspecific parameters parts characterization transcriptional regulatory modules

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