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Experimental Investigation on the Strength and Ductility Performance of Steel-Timber-Steel Joints with Screw and Steel-Tube Fasteners

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Journal of Renewable Materials 2023年第12期11卷 4175-4195页

作者： Huifeng Yang Mingwang Wu Rixin Gu Hang Cao Kai Xiao Benkai Shi College of Civil Engineering Nanjing Tech UniversityNanjing211816China

This article presents experimental results of steel-timber-steel(STS)joints loaded parallel to grain.Eight groups of specimens were designed,and tensile tests were performed.The fastener types and fastener numbers were considered to evaluate the tensile strengths and ductility performances of the STS joints.The screws with 6 mm diameter and the innovative steel-tubes with 18 mm diameter were adopted as connecting fasteners.The experimental results were discussed in terms of yielding and ultimate strengths,slip stiffness,and ductility factors.The ductility classification and failure mechanisms of each group of specimens were analyzed.It was demonstrated that the STS joint with large diameter steel-tubes showed acceptable ductility,which was close to the ductility of the STS joint with small diameter screws,thanks to the hollow structure of the steel-tube.The theoretical strengths of various failure modes for the joints with small diameter screws or large diameter steel-tubes were calculated and compared with the experimental results.The ductile performance of the STS joint was discussed by comparing the theoretical strengths of various failure modes.The effective number of the STS joint with multifasteners was also analyzed by considering the failure mechanisms in aspects of tensile strength and slip stiffness.

关键词： Steel-timber-steel joint screw steel-tube ductility experimental investigation timber structure

Spatial distribution and export of nutrients and metal elements in the subterranean estuary of Daya Bay

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海洋学报:英文版 2023年第8期42卷 77-86页

作者： Zhaoxi Liu Mingchen Ge Qianqian Wang Xuejing Wang Kai Xiao Gang Li Hailong Li School of Water Resources and Environmental Science China University of GeosciencesBeijing 100083China School of Environmental Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Institute of Surface-Earth System Science School of Earth System ScienceTianjin UniversityTianjin 300072China

Subterranean estuaries(STE)are important seawater-groundwater mixing zones with complex biogeochemical processes,which play a vital role in the migration and transformation of dissolved materials.In this study,we first investigated the spatial distributions of dissolved inorganic nitrogen(DIN),dissolved inorganic phosphorous(DIP),dissolved inorganic silicon(DSi)and metal elements(As,Ba,Cr,Cu,Fe,Mn,Ni,Pb,and Zn)in STE including upper intertidal,seepage face and subtidal zones.We then estimated submarine groundwater discharge(SGD)and associated nutrient and metal element fluxes.From the generalized Darcy’s law method,SGD was estimated to be 30.13 cm/d,which was about 7 times larger than the inflow(4.16 cm/d).The nutrient and metal fluxes from SGD were estimated to be(5.33±4.99)mmol/(m^(2)·d)for DIN,(0.22±0.03)mmol/(m^(2)·d)for DIP,(16.20±2.05)mmol/(m^(2)·d)for DSi,(1325.06±99.10)μmol/(m^(2)·d)for Fe,(143.41±25.13)μmol/(m^(2)·d)for Mn,(304.06±81.07)μmol/(m^(2)·d)for Zn,(140.21±13.33)μmol/(m^(2)·d)for Cu,(84.49±2.94)μmol/(m^(2)·d)for Pb,(37.38±5.51)μmol/(m^(2)·d)for Ba,(27.88±3.89)μmol/(m^(2)·d)for Cr,(10.10±6.33)μmol/(m^(2)·d)for Ni,and(6.25±3.45)μmol/(m^(2)·d)for As.The nutrient and metal fluxes from SGD were relatively higher than those from the inflow,suggesting that nearshore groundwater acted as the sources of nutrients and metal elements discharging into the sea.The environmental potential pollution of coastal seawater was evaluated by pollution factor index(Pi),comprehensive water quality index(CWQI),and ecological risk index(ERI).Pb mainly caused potential danger of nearshore environment with considerable contamination(Pi=5.78±0.19),heavy pollution(CWQI=4.09)and high ecological risk(ERI=18.00).This study contributed to better understanding the behavior of nutrients and metal elements and improving the sustainable management of STE under the pressure of anthropogenic activities and climate change.

关键词： subterranean estuaries submarine groundwater discharge nutrients metal elements pollution assessment Daya Bay

Chronic Kidney Disease Induces Cognitive Impairment in the Early Stage

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Current Medical Science 2023年第5期43卷 988-997页

作者： Yu WANG kai CHEN Zi-xuan QIAO xiao-rong BAO Department of Nephrology Jinshan HospitalFudan UniversityShanghai 201508China

Objective Previous research indicates a link between cognitive impairment and chronic kidney disease(CKD),but the underlying factors are not fully understood.This study aimed to investigate the progression of CKD-induced cognitive impairment and the involvement of cognition-related proteins by developing early-and late-stage CKD models in Sprague-Dawley rats.Methods The Morris water maze test and the step-down passive avoidance task were performed to evaluate the cognitive abilities of the rats at 24 weeks after surgery.Histopathologic examinations were conducted to examine renal and hippocampal damage.Real-time PCR,Western blotting analysis,and immunohistochemical staining were carried out to determine the hippocampal expression of brain-derived neurotrophic factor(BDNF),choline acetyltransferase(ChAT),and synaptophysin(SYP).Results Compared with the control rats,the rats with early-stage CKD exhibited mild renal damage,while those with late-stage CKD showed significantly increased serum creatinine levels as well as apparent renal and brain damage.The rats with early-stage CKD also demonstrated significantly impaired learning abilities and memory compared with the control rats,with further deterioration observed in the rats with late-stage CKD.Additionally,we observed a significant downregulation of cognition-related proteins in the hippocampus of rats with early-stage CKD,which was further exacerbated with declining renal function as well as worsening brain and renal damage in rats with late-stage CKD.Conclusion These results suggest the importance of early screening to identify CKD-induced cognitive dysfunction promptly.In addition,the downregulation of cognition-related proteins may play a role in the progression of cognitive dysfunction.

关键词： chronic kidney disease cognitive impairment Morris water maze test brain-derived neurotrophic factor choline acetyltransferase synaptophysin

Expression and prognosis of inducible T-cell co-stimulator and its ligand in Chinese stage I–III lung adenocarcinoma patients

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Animal Models and Experimental Medicine 2023年第5期6卷 464-473页

作者： xiao-kai Zhan Xi-Kun Liu Sen Zhang Hong Chen Division of Oncology and Hematology Beijing Chao-Yang HospitalCapital Medical UniversityBeijingP.R.China State Key Laboratory of Bioactive Substances and Functions of Natural Medicines Institute of Materia MedicaChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingP.R.China Pathology Department Beijing Chao-Yang HospitalCapital Medical UniversityBeijingP.R.China

Background:Immunotherapy has become the fastest-adopting treatment paradigm for lung cancer with improved survival.By binding with its ligand(inducible T-cell costimulator and its ligand[ICOSL]),an inducible T-cell co-stimulator(ICOS)could contribute to reversing immunosuppression and improving immune response and thus be a potential target for cancer immunotherapy.Methods:We selected 54 formalin-fixed,paraffin-embedded tumor tissues from cases with stage I–III lung adenocarcinoma cancer.Immunohistochemical expression of ICOS and ICOSL was evaluated.The correlation with clinical parameters in Chinese patients was also compared with TCGA results.Results:The positive rates of ICOS and ICOSL were 68%and 81.5%,respectively,in lung tumor tissues.Of these,9 cases had a low expression of ICOS,and 22 cases had a high expression of ICOS;ICOSL expression was low in 20 cases and high in 24 cases.According to the International Association for the Study of Lung Cancer(8th edition),phase I lesions were detected in 21 cases,phase II lesions in 15 cases,and phase III lesions in 18 cases.The median survival time of all patients was 44.5 months,and the median disease-free survival was 32 months.Univariate analysis showed that the factors significantly associated with overall survival were tumor size,regional lymph node involvement,stage,and expression level of ICOS/ICOSL.Survival analysis using log-rank test indicated that the lower ICOS+cell infiltration may predict poor prognosis,whereas lower ICOSL protein expression may be associated with better prognosis,but ICOSL data need further validation in larger samples due to inconsistency in TCGA mRNA prediction.Conclusion:ICOS/ICOSL might be associated with prognosis of lung cancer,and ICOS and its ligand may be potential therapeutic targets in non-small cell lung cancer.

关键词： Chinese patients ICOS ICOSL lung adenocarcinoma prognostic factor

Geochemical Characteristics of the Upper Permian Longtan Formation from Northeastern Sichuan Basin:Implications for the Depositional Environment and Organic Matter Enrichment

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Acta Geologica Sinica(English Edition) 2023年第4期97卷 1196-1213页

作者： xiao Wei ZHANG Bing YANG kai WANG Yan WEN Siyu MA kai CAO Gaoquan Earth Exploration and Information Technology Key Laboratory of Ministry of Education Chengdu University of TechnologyChengdu 610059China State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Chengdu University of TechnologyChengdu 610059China Institute of sedimentary geology Chengdu University of TechnologyChengdu 610059China

A set of organic-rich shales of the upper Permian Longtan Formation,which is widely developed in the northeastern part of the Sichuan Basin,is a key formation for the next step of exploration and development.At present,most studies on this set of formations have focused on the reservoir characteristics and reservoir formation mechanism of the shales,and basic studies on the palaeoenvironment and organic matter(OM)enrichment mechanism have not been fully carried out.In this paper,we recovered the sedimentary palaeoenvironment by mineralogical,elemental geochemical and organic geochemical analyses,and explored the enrichment mechanism of OM under the constraints of palaeoenvironmental evolution.The shales can be divided into two stages of sedimentary evolution:compared with the shales of the Lower Longtan Formation,the shales of the Upper Longtan Formation are relatively rich in quartz,poor in clay and carbonate minerals,and the OM type changes from typeⅢto typeⅡ_(2).The depositional environment has undergone a change from sea level rise,from warm and wet climate to dry and cold climate,and from oxygen-poor condition restricted to open reduction environment;the land source input has decreased,the siliceous mineral content has increased,the biological productivity has improved,and the deposition rate has changed from high to low.A depositional model was established for the shales of the Longtan Formation,reflecting the differential reservoir formation pattern of organic matter.For the Lower Longtan Formation shales,the most important factors controlling OM content are terrestrial source input and deposition rate,followed by paleoclimate and paleooxygen conditions.For the Upper Longtan Formation shales,the most important controlling factor is paleo-productivity,followed by sedimentation rate.The depositional model constructed for the Upper and Lower Longtan Formation shales can reproduce the enrichment of organic matter and provide a basis for later exploration and development.

关键词： geochemical characteristics sedimentary environment organic matter accumulation upper Permian northeastern Sichuan Basin

Low Grip Strength and Increased Mortality Hazard among Middle-Aged and Older Chinese Adults with Chronic Diseases

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Biomedical and Environmental Sciences 2023年第3期36卷 213-221页

作者： XIE kai Hong HAN xiao ZHENG Wei Jun ZHUANG Su Fang School of Nursing Zhejiang Chinese Medical UniversityHangzhou 311400ZhejiangChina School of health humanities Peking UniversityBeijing 100000China School of Public Health Zhejiang Chinese Medical UniversityHangzhou 311400ZhejiangChina Office of Disciplinary Inspection and Supervision The Third Affiliated Hospital of Zhejiang Chinese Medical UniversityHangzhou 311006ZhejiangChina

Objective This study aims to evaluate the association between lower grip strength and mortality hazard.Methods We selected 10,280 adults aged 45 to 96 years old from the China Health and Retirement Longitudinal Study and used multivariate Cox proportional hazard models to assess the association of grip strength with mortality hazard.In addition,we explored the possibility of a nonlinear relationship using a 4-knot restricted spline regression.Results We found that elevated grip strength was associated with lower mortality up to a certain threshold.The baseline quartile values of grip strength were 30,37,and 44 kg for males and 25,30,and35 kg for females.After adjusting for confounders,with category 1 as the reference group,the adjusted HRs were 0.58(0.42-0.79)in males and 0.70(0.48-0.99)in females(category 4).We also found a linear association between grip strength values and all-cause death risk(males,P=0.274;females,P=0.883)using restricted spline regression.For males with a grip strength<37 kg and females with a grip strength<30 kg,grip strength and death were negatively associated.Conclusion Grip strength below a sex-specific threshold is inversely associated with mortality hazard among middle-aged and older Chinese adults with chronic diseases.

关键词： Grip strength Death Chronic disease

Improving Ductility and Anisotropy by Dynamic Recrystallization in Ti/Mg Laminated Metal Composite

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Acta Metallurgica Sinica(English Letters) 2022年第12期35卷 1946-1958页

作者： Taiqian Mo Huaqiang xiao Bo Lin Wei Li kai Ma School of Mechanical Engineering Guizhou UniversityGuiyang 550025China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Ti/Mg laminated metal composites(LMCs)were processed by hot roll bonding and subsequent annealing at 200℃and300℃for 1 h,and the effect of dynamic recrystallization on the microstructure and anisotropy behavior was investigated in detail.The results revealed that,in both as-rolled and annealed Ti/Mg LMCs,the inhomogeneous distribution in the microstructure of Mg layers near the interface and near the center was related to the effect of friction between the roller and sheet surface and uncoordinated deformation between constituent layers.With increasing annealing temperature,Ti/Mg LMCs exhibited excellent elongation without sacrificing strength properties,which was mainly due to the improvement in bonding strength and the increasing strain gradient at the interface between soft and hard layers after annealing treatment.Besides,the increasing Schmid factors(SFs)of prismatic slip and pyramidal slip in Mg layers contributed to the improved plastic deformation ability of Ti/Mg LMCs.The experimental analysis indicated that the presence of Mg alloys resulted in the microstructure and mechanical properties of LMCs were different along various loading directions,and annealing treatment can effectively inhibit the anisotropic behavior of Ti/Mg LMCs resulting from the weakening of basal texture in the Mg layer.

关键词： Ti/Mg laminated metal composites Dynamic recrystallization Microstructure Mechanical propertiesAnisotropy

Investigation on thermal characteristics and desensitization mechanism of improved step ladder-structured nitrocellulose

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Defence Technology（防务技术） 2023年第2期20卷 93-102页

作者： Cheng-kai Pu Yu Luan Ming-jun Yi Zheng-gang xiao Key Laboratory of Special Energy Materials Ministry of EducationSchool of Chemistry and Chemical EngineeringNanjing University of Science and TechnologyNanjing210094People's Republic of China

Nitrocellulose,or cellulose nitrate,has received considerable interest due to its various applications,such as propellants,coating agents and gas generators.However,its high mechanical sensitivity caused many accidents during its storage and usage in ammunition.In this work,two kinds of insensitive step ladderstructured nitrocellulose(LNC)with different nitrogen contents were synthesized.The products were characterized by FT-IR,Raman,XRD,SEM,elemental analysis,TGA,DSC,accelerating rate calorimeter analysis(ARC),and drop weight test to study their molecular structure,thermal characteristics and desensitization performance.Compared with raw nitrocellulose,LNC has a sharper exothermic peak in the DSC and ARC curves.The H50values of the two kinds of LNC increased from 25.76 to 30.01 cm for low nitrogen content and from 18.02 to 21.84 cm for high nitrogen content,respectively.The results show that the ladder-structure of LNC which provides regular molecular arrangement and a soft buffer made with polyethylene glycol could affect the energy releasing process of LNC and reduce the sensitivity of LNC.Insensitive LNC provides an alternative to be used as a binder in insensitive propellants formulation.

关键词： Nitrocellulose Decomposition Desensitization Ladder structure Thermal characteristic Polyethylene glycol

A practical ANN model for predicting the excavation-induced tunnel horizontal displacement in soft soils

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Underground Space 2022年第2期7卷 278-293页

作者： Zhong-kai Huang Dong-Mei Zhang xiao-Chuang Xie Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Department of Geotechnical EngineeringTongji UniversityShanghaiChina

The objective of this study is to propose an artificial neural network(ANN)model to predict the excavation-induced tunnel horizontal displacement in soft soils.For this purpose,a series of finite element data sets from rigorously verified numerical models were collected to be utilized for the development of the ANN model.The excavation width,the excavation depth,the retaining wall thickness,the ratio of the average shear strength to the vertical effective stress,the ratio of the average unloading/reloading Young’s modulus to the vertical effective stress,the horizontal distance between the tunnel and retaining wall,and the ratio of the buried depth of the tunnel crown to the excavation depth were chosen as the input variables,while the excavation-induced tunnel horizontal displacement was considered as an output variable.The results demonstrated the feasibility of the developed ANN model to predict the excavation-induced tunnel horizontal displacement.The proposed ANN model in this study can be applied to predict the excavation-induced tunnel horizontal displacement in soft soils for practical risk assessment and mitigation decision.

关键词： Artificial neural network Excavation Tunnel horizontal displacement Soft soils