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Numerical simulations of failure behavior around a circular opening in a non-persistently jointed rock mass under biaxial compression

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International Journal of Mining Science and Technology 2016年第4期26卷 729-738页

作者： Yang Xuxu Jing Hongwen Chen kunfu Rock Mass Modeling and Computational Rock Mechanics Laboratories University of Arizona State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and Technology

Pre-existing discontinuities change the mechanical properties of rock masses,and further influence failure behavior around an underground *** present study,the failure behavior in both Inner and Outer zones around a circular opening in a non-persistently jointed rock mass under biaxial compression was investigated through numerical ***,the micro parameters of the PFC^(3D) model were carefully calibrated using the macro mechanical properties determined in physical experiments implemented on jointed rock ***,a parametrical study was undertaken of the effect of stress condition,joint dip angle and joint *** low initial stress,the confining stress improves the mechanical behavior of the surrounding rock masses;while under high initial stress,the surrounding rock mass failed immediately following *** small dip angles the cracks around the circular opening developed generally outwards in a step-path failure pattern;whereas,at high dip angles the surrounding rock mass failed in an instantaneous intact rock failure ***,the stability of the rock mass around the circular opening deteriorated significantly with increasing joint persistency.

关键词： Underground opening Failure behavior Non-persistent joints Rock mass PFC^3D

Stress evolution and support mechanism of a bolt anchored in a rock mass with a weak interlayer

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International Journal of Mining Science and Technology 2017年第3期27卷 573-580页

作者： Ding Shuxue Jing Hongwen Chen kunfu Xu Guo'an Meng Bo State Key Laboratory for Geomechanics & Deep Underground Engineering School of Mechanics and Civil Engineering China University of Mining & Technology Xuzhou 221116 China

By applying experimental method, the bolt stress and supporting mechanism is studied during the deformation process of a rock mass containing a weak interlayer. The force measuring bolt is installed manually and instrumented five pairs of symmetrical strain gauges. The experimental results show that the fully grouted bolt suffers tensile, compressive, bending and shear stress at the same time. The bolt stress evolution is closely related to the deformation stages of the rock mass which are very gradually varying stage, gradually varying stage at the pre-peak and suddenly varying stage at the post peak *** axial compressive stress in the bolt is mainly induced by the moment. Thus, in most cases the axial compressive stress is distributed on one side of the bolt. For axial stresses, induced by the axial force and the bending moment at the post-peak stage, three types of changing are observed, viz. increasingincreasing type, decreasing-increasing type and increasing-decreasing type. The stress characteristics of the bolt section in the weak interlayer are significantly different from those in the hard rock. The failure models of the anchored bolt are tensile failure and shear failure, respectively. The bolt not only provides constraints on the free surface of the rock mass, but also resists the axial and lateral loading by the bending moment. This study provides valuable guidelines for bolting support design and its safety assessment.

关键词： Fully grouted bolt Stress evolution Support mechanism Weak interlayer Deformation process

Failure mechanism and stability control of a large section of very soft roadway surrounding rock shear slip

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International Journal of Mining Science and Technology 2013年第1期23卷 127-134页

作者： Meng Bo Jing Hongwen Chen kunfu Su Haijian State Key Laboratory of Geomechanics and Deep Underground Engineering China University of Mining & Technology School of Mechanics and Civil Engineering China University of Mining & Technology

The measured data and simulation test phenomenon of surrounding rock deformation and failure at the project site indicate that shear failure which firstly occurs in surrounding rock, block slip and second shear failure are the root cause of deformation and damage of supporting structure of the surrounding rock at a large scale. We derived limit load of surrounding rock shear slip failure and reasonable support resistance of given load by means of shear slip line field theory, discussed the main factors which influence the limit load of surrounding rock. Shear slip line field and limit load of circular tunnel surrounding rock were obtained by means of physical simulation test, which agreed well with the theoretical analysis results. Based on the theoretical analysis and physical simulation test, the cause deformation and failure at large scale of Xinshanghai No. 1 coal mine big section ingate was analyzed, and the shear failure resistance and block slip in surrounding rock were proposed as the core technical supporting ideas. Proper range of supporting resistance which came from calculation was suggested. The support scheme which is mainly composed of large grouting anchor, sprayed anchor net support technique and full-face grille concrete finally ended the dilemma of repeated failure and mending of ingate and created critical conditions for smooth production in the coal mine.

关键词： Rock mechanics Surrounding rock Shear and slip Shear and slip resistance Limit load

Effects of riboflavin and desferrioxamine B on Fe(Ⅱ)oxidation by 0_(2)

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Fundamental Research 2022年第2期2卷 208-217页

作者： Peng Zhang Philippe Van Cappellen kunfu Pi Songhu Yuan State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences68 Jincheng StreetEast Lake High-Tech Development ZoneWuhanHubei 430078China Ecohydrology Research Group Water Institute and Department of Earth and Environmental SciencesUniversity of WaterlooWaterlooOntario N2L 3G1Canada Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science School of Environmental StudiesChina University of Geosciences68 Jincheng StreetEast Lake High-Tech Development ZoneWuhanHubei 430078China

Flavins and siderophores secreted by various plants,fungi and bacteria under iron(Fe)deficient conditions play important roles in the biogeochemical cycling of Fe in the *** the mechanisms of flavin and siderophore mediated Fe(Ⅱ)reduction and dissolution under anoxic conditions have been widely studied,the influence of these compounds on Fe(ID)oxidation under oxic conditions is still *** this study,we investi-gated the kinetics of aqueous Fe(Ⅱ)(17.8μM)oxidation by O_(2)at pH 5-7 in the presence of riboflavin(oxidized(RBF)and reduced(RBFH_(2)))and desferrioxamine B(DFOB)as representative flavins and siderophores,*** showed that the addition of RBF/RBFH_(2)or DFOB markedly accelerates the oxidation of aqueous Fe(Ⅱ)by O_(2).For instance,at pH 6,the rate of Fe(Ⅱ)oxidation was enhanced 20-70 times when 10μM RBFH_(2)was *** mechanisms responsible for the accelerated Fe(Ⅰ)oxidation are related to the redox reactivity and complexation ability of RBFH_(2),RBF and *** RBFH_(2)does not readily complex Fe(Ⅰ)/Fe(Ⅱ),it can activate O_(2)and generate reactive oxygen species,which then rapidly oxidize Fe(Ⅱ).In contrast,both RBF and DFOB do not reduce O_(2)but react with Fe(Ⅱ)to form RBF/DFOB-complexed Fe(Ⅱ),which in turn accelerates Fe(Ⅰ)***,the lower standard reduction potential of the Fe(Ⅰ)-DFOB complex,compared to the Fe(Ⅰ)-RBF complex,correlates with a higher oxidation rate constant for the Fe(Ⅰ)-DFOB *** study reveals an overlooked catalytic role of flavins and siderophores that may contribute to Fe(Ⅱ)/Fe(Ⅱ)cycling at oxic-anoxic interfaces.

关键词： Riboflavin Desferrioxamine B Ferrous iron Abiotic oxidation Oxygen

Does the Domestic Value Added Induced by China's Exports Really Belong to China?

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China & World Economy 2012年第5期20卷 83-102页

作者： Yuwan Duan Cuihong Yang kunfu Zhu Xikang Chen Academy of Mathematics and Systems Science Chinese Academy of Sciences

Since 2001, the exports of foreign-invested enterprises （FIEs） have accounted for more than 50percent of China＇s total exports. As foreign capital occupies a high proportion of the total capital of FIEs, most FIEs ＇ capital gains are foreign factor income. Although these gains are calculated as apart of China＇s GDP, they do not belong to China＇s national income. To determine the real contribution of exports to China ＂s welfare, the present paper analyses the impact of exports on China ＂s national income using a non-competitive input output model capturing processing trade. The results show that every US$1000 of China＇s exports generates US$506.8 of national income. The real contribution of exports to China ＂s welfare is much smaller than what we expected. This suggests that China should endeavor to improve the gains from international markets orfind another engine to maintain its economic growth.

关键词： domestic factor income domestic value added exports foreign factor income

Effects of extrusion and enzymatic debranching on the structural characteristics and digestibility of corn and potato starches

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Food Bioscience 2022年第3期47卷 654-661页

作者： Qing Liu Yihui Wang Yueyue Yang Shichao Bian Xing Zhou kunfu Zhu Lulian Xu Zhengyu Jin Aiquan Jiao State Key Laboratory of Food Science and Technology Jiangnan UniversityWuxi214122China School of Food Science and Technology Jiangnan UniversityWuxi214122China Shandong Zhushi Pharmaceutical Group Co. LtdHeze274300China Department of Pediatric Endocrinology The Affiliated Wuxi Children's Hospital of Nanjing Medical UniversityWuxi214023China Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province Jiangnan UniversityWuxi214122China

Amylose content has a profound impact on the contents of slowly digestible starch and resistant *** debranching is a safe method to increase the amylose content,however,the lower substrate concentration and high viscosity of fully gelatinized starch limit the efficiency and yield of this *** paper aims to explore the effects of extrusion and enzymatic debranching on increasing the amylose content thereby increasing slowly digestible starch and resistant starch *** starch concentrations (10%,15%,and 20%) of extruded corn starch (ECS) and extruded potato starch (EPS) were used to *** debranched ECS and debranched EPS showed high amylose content of approximately 90%,indicating that all samples with different starch concentrations achieved high-efficiency enzymatic *** high-performance liquid chromatograph results indicated that the samples were mainly short *** samples exhibit a typical B-type crystalline structure and the relative crystallinity of them exceeds 37%.The short amylose exhibited rapid rearrangement ability,with the gelatinization temperature range of rescanning determined as 80–125℃,this will facilitate the formation of slowly digestible starch and resistant *** slowly digestible starch and resistant starch contents of the samples (debranched ECS and debranched EPS) were between 23% and 30% and between 31% and 37%,*** results indicate that the extrusion and enzymatic debranching of a high substrate concentration can efficiently increase the amylose content,thereby significantly reducing the digestibility of starch,and has broad prospects of the actual production of slowly digestible starch and resistant starch.

关键词： Starch Extrusion Enzymatic debranching Structural characteristics Digestibility

Effects of different ratios of soluble to insoluble dietary fiber on growth performance and intestinal health of piglets

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Animal Nutrition 2024年第3期18卷 257-271页

作者： Luya Feng Zhenfu Luo Jing Wang kunfu Wu Wenliang Wang Zhimou Liu Juping Wen Zhenbin Wang Gregory JDuns Xiaokang Ma Bi'e Tan Hunan Provincial Key Laboratory for the Products Quality Regulation of Livestock and Poultry College of Animal Science and TechnologyHunan Agricultural UniversityChangsha 410128China Yuelushan Laboratory Changsha 410128China Hunan Nuoze Biological Technology Co. Ltd.Yiyang 413001China

This study investigated the impact of different ratios of soluble to insoluble dietary fiber(SDF:IDF)formulations by sugar beet pulp(SBP)supplementation on piglet growth performance,nutrient digestibility,immune function,intestinal morphology,intestinal microbiota and intestinal health.A total of 60 crossbred piglets(Duroc×[Landrace×Yorkshire])at 40 d old with body weight of 10.0±0.3 kg were randomly assigned to 5 treatments with 6 replicates per treatment and 2 piglets per replicate in a 21-d *** dietary treatments included a corn-soybean meal diet(0%SBP supplementation;CON),and diets supplemented with 2%,4%,6%,and 8%SBP,representing different SDF:IDF ratios at 10.16%,13.53%,16.79%,19.86%,and 24.81%,*** results indicated that the 8%SBP treatment had a negative effect on feed-to-gain ratio(linear,P=0.009)compared with the CON treatment(P=0.021).The apparent total tract digestibility(ATTD)of crude protein was lower in treatments supplemented with SBP(P=0.002)and showed a linear decrease(P=0.001),while the ATTD of IDF showed a linear increase(P=0.037)in four SBP treatments compared to the CON *** 4%SBP treatment increased serum concentrations of triglyceride(quadratic,P=0.019)and K(linear,P<0.0037),and decreased alanine transaminase concentration(quadratic,P=0.015)compared with the CON *** concentrations of Cit,Cys,Ile,Leu,Orn,Arg,taurine,urea,1-methylhistidine,α-aminoadipic acid,α-aminobutyric acid and cystathionine in the 4%SBP treatment were highest among all treatments(P<0.05).The serum concentrations of interleukin-6,interleukin-8,interleukin-10,transforming growth factor-β,and tumor necrosis factor-αin the 6%SBP treatment were higher than those in the CON treatment(P<0.05),which also increased mucin-2 and G protein-coupled receptor 41 mRNA expression(P<0.05)in colonic mucosa compared with the CON treatment and improved the intestinal barrier *** containing more than 19.86%SDF:IDF could impair the intestinal healt

关键词： Soluble dietary fiber Insoluble dietary fiber Sugar beet pulp Growth performance Intestinal health Piglet

IP3R-mediated Ca2＋ signals govern hematopoietic and cardiac divergence of Flk1＋ cells via the calcineurin-N FATc3-Etv2 pathway

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Journal of Molecular Cell Biology 2017年第4期9卷 274-288页

作者： Yi-Jie Wang Jijun Huang Wenqiang Liu Xiaochen Kou Huayuan Tang Hong Wang Xiujian Yu Shaorong Gao kunfu Ouyang Huang-Tian Yang Key Laboratory of Stem Cell Biology and Laboratory of Molecular Cardiology Institute of Health Sciences Shanghai Institutes for Biological Sciences Chinese Academy of Sciences & Shanghai liao Tong University School of Medicine Shanghai 200031 China Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital School of Life Sciences and Technology Tongji University Shanghai 200092 China Drug Discovery Center Key Laboratory of Chemical Genomics Peking University Shenzhen Graduate School Shenzhen 518055 China Second Affiliated Hospital/Zhejiang University Hangzhou 310009 China

Ca2＋ signals participate in various cellular processes with spatial and temporal dynamics, among which, inositol 1,4,5-trisphosphate receptors （IP3Rs）-mediated Ca2＋ signals are essential for early development. However, the underlying mechanisms of IP3R- regulated cell fate decision remain largely unknown. Here we report that IP3Rs are required for the hematopoietic and cardiac fate divergence of mouse embryonic stem cells （mESCs）. Deletion of IP3Rs （IP3R-tKO） reduced FIkl＋/PDGFRα- hematopoietic mesoderm, c-Kit＋/CD41＋ hematopoietic progenitor ceil population, and the colony-forming unit activity, but increased cardiac progenitor markers as well as cardiomyocytes. Concomitantly, the expression of a key regulator of hematopoiesis, Ely2, was reduced in IP3R-tKO cells, which could be rescued by the activation of Ca2＋ signals and calcineurin or overexpression of constitutively active form of NFATc3. Furthermore, IP3R-tKO impaired specific targeting of Ely2 by NFATc3 via its evolutionarily conserved cis-element in differentiating ESCs. Importantly, the activation of Ca2＋-calcineurin-NFAT pathway reversed the phenotype of IP3R-tKO cells. These findings reveal an unrecognized governing role of IP3Rs in hematopoietic and cardiac fate commitment via IP3Rs-Ca2＋-calcineurin-NFATc3- Etv2 pathway.

关键词： IP3Rs Ca2+ signals mesoderm specification hematopoietic and cardiac fate Etv2

MicroRNAs Regulate the Wnt/Ca2+ Signaling Pathway to Promote the Secretion of Insulin in Pancreatic Beta Cells

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MicroRNAs Regulate the Wnt/Ca2+ Signaling Pathway to Promote...