检索结果-南通市图书馆

China Foundry 2019年第1期16卷 53-62页

作者： Xiao-feng Huang Ya-jie ma qiao-qiao Zhang Lang-lang Wei Jian-qiao Yang State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals Lanzhou University of TechnologyLanzhou 730050China

The content and kind of trace elements in magnesium alloys have important effects on their ascast and semi-solid microstructures. In this research work, effects of trace Cr on as-cast and semi-solid microstructures of ZC61 magnesium alloy were investigated by metal mold casting and semi-solid isothermal heat treatment. The results show that the addition of Cr can refine the α-Mg phase without generating a new phase, noticeably change the eutectic phase, and decrease the average size of solid particles at the same isothermal heat treatment conditions. Non-dendritic microstructures of all alloys are constituted of α_1-Mg phases, α_2-Mg phases and eutectic phases after water quenching. With isothermal temperature increased or holding time prolonged, the eutectic microstructure(α-Mg+MgZn_2+CuMgZn) at the grain boundaries in as-cast alloy is melted preferentially and then turned into semi-solid non-dendritic microstructure by processes of initial coarsening, microstructure separation, spheroidizing and final coarsening. Especially when the ZC61-0.1 Cr alloy was treated at 585 ℃ for 30 min, the ideal non-dendritic microstructure can be obtained, and the corresponding solid particle size and shape factor were 37.5 μm and 1.33, respectively. The coarsening process of solid α-Mg phase at higher temperature or longer time, which is affected by both combining growth and Ostwald ripening mechanism, is refrained when Cr is added to the ZC61 alloy.

关键词： ZC61 magnesium alloy Cr content semi-solid isothermal heat treatment non-dendritic microstructure microstructural evolution

Influential factors of spatial performance in metro-led urban underground public space:A case study in Shanghai

在线全文

学校读者我要写书评

暂无评论

Underground Space 2023年第1期8卷 229-251页

作者： Chen-Xiao ma Fang-Le Peng Yong-Kang qiao Hu Li Research Center for Underground Space&Department of Geotechnical Engineering Tongji UniversityShanghai 200092PR China Ji’nan Rail Transit Group Co. Ltd.Ji’nan 250014Shandong ProvincePR China

Spatial performance measures the space usage of each underground segment in metro-led urban underground public space(UUPS).It usually varies in different UUPS segments and at different *** environmental factors and space attractors can influence spatial performance in UUPS including spatial configurations,transportation facilities,space design characteristics,and commercial and work-ing *** study intends to figure out the temporal and spatial distribution patterns of spatial performance in UUPS and then reveal the main influential factors and their impact *** UUPS in Jiangwan–Wujiaochang Sub-center was selected as the study *** counting methods and multiple regression models were employed to collect the pedestrian data and quantitatively analyze the correlations between pedestrian flows and candidate influential *** study verified that spatial configurations were the most important factors instead of underground or surface *** existed an interactive effect among pedestrian move-ments,spatial configurations,and commerce distribution in metro-led *** width and the distribution of metro stations could partly affect spatial *** influential mechanisms of metro stations were different on weekdays and at *** segments belonging to shopping malls in UUPS had a negative impact on spatial performance only on *** of this study can provide insights for more efficient layout planning and design of metro-led UUPS in Chinese metropolitan cities.

关键词： Urban underground public space Metro-led area Spatial performance Cordon count Multiple regression method

Numerical simulation of mechanical properties of straight pipe and elbow during in-service welding

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Welding 2018年第4期27卷 33-40页

作者： qiao ling Han Tao College of Mechanical and Electronic Engineering China University of Petroleum

Elbows are the most vulnerable parts in pipeline network systems. The residual stress for in-service welding repair has significant impacts on the mechanical properties of straight pipes and elbows. In this paper,the thermal elastic-plastic finite element method is employed to investigate the mechanical field during the in-service welding. The prediction of residual stress and deformation in the straight pipe and elbow is performed based on the validation of the numerical models. And the effects of the curvature radius and defects on the elbow are investigated. The results show that the residual stress distribution is uneven along various directions after welding. And the mechanical properties of the elbow decrease when the curvature radius is small. Compared to the intact elbow,the residual stress of the elbow with defects concentrates in the defective area. The depth of defect is the main factors affecting the mechanical properties of the elbow. A systematic analysis of the mechanical properties of straight pipes and elbows is proposed to provide guidance to the in-service welding.

关键词： in-service welding elbow residual stress curvature radius pressure defects

THE STUDY OF THE YELLOW SEA WARM CURRENT AND ITS SEASONAL VARIABILITY

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2009年第2期21卷 159-165页

作者： XU ling-ling WU De-xing LIN Xiao-pei ma Chao Physical Oceanography Laboratory Ocean University of China Qingdao 266100 China

The Yellow Sea Warm Current （YSWC） penetrates northward along the Yellow Sea Trough, and brings warm and saline water towards the Bohai Sea. The YSWC becomes much less intrusive in summer and is limited mostly in the southern trough, contrasting with a deep winter penetration well into the trough. The seasonal variability of the YSWC has prompted a debate regarding which controls the YSWC and its seasonal variability. In this article, the annual mean and seasonal variability of the YSWC was examined by using a 3-D ocean model together with several experiments. The results show that in the annual mean the YSWC is a compensating current firstly for the southward Korea Coastal Current （KCC）, which is mainly caused by the Kuroshio Current （KC）. The local wind-stress forcing plays an important but secondary role. However, the local monsoonal forcing plays a prominent role in modulating the seasonal variability. A deep northwestward intrusion of the YSWC in winter, for instance, is mainly due to a robustly developed China Coastal Current （CCC） which draws water along the Yellow Sea trough to feed a southward flow all the way from the Bohai Sea to the Taiwan Strait.

关键词： Yellow Sea Warm Current (YSWC) Kuroshio local wind monsoon

PI3K/Akt/mTOR Signaling as Targets for Developing Anticancer Agents from marine Organisms

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean University of China 2021年第3期20卷 688-694页

作者： GUO Mingyue ZUO ling qiao Gan LIU Minghua CAO Shousong LIN Xiukun Department of Pharmacology School of PharmacySouthwest Medical UniversityLuzhou 646000China Central Nervous System Drug Key Laboratory of Sichuan Province Luzhou 646000China

The PI3K/Akt/mTOR signaling pathway is one of the most frequently dysregulated pathways in *** the PI3K-mediated pathway has been an important strategy for developing novel anticancer *** the past decades,more than 40 inhibitors of the PI3K/Akt/mTOR pathway have been developed at different clinical ***,everolimus,idelalisib,and copanlisib have been approved for clinical use by the Food and Drug Administration of the United States(FDA).However,the toxic-ity and drug resistance limit their efficiency in the *** compounds with greater potency and selectivity,as well as im-proved therapeutic indices with reduced toxicity,are clearly *** the past three decades,a lot of bioactive ingredients with anticancer effects by affecting the PI3K-mediated pathways have been found from marine *** the present mini-review,anticancer compounds from marine source that target the PI3K/Akt/mTOR signaling were *** molecular entities and their modes of action were *** marine compounds targeting special factors of the PI3K/Akt/mTOR were highlighted.

关键词： marine organisms PI3K/Akt/mTOR pathway anticancer activity

Effect of geometric shape of plate on residual stress and deformation distribution for butt-weld joint

在线全文

学校读者我要写书评

暂无评论

China Welding 2018年第3期27卷 20-26页

作者： qiao ling Han Tao College of Mechanical and Electronic Engineering China University of PetroleumQingdao 266580China

This paper presents a numerical simulation of deformation and residual stress in butt-weld joint for different shaped plates. Within the framework of numerical investigation, 3 types of models and a double ellipsoidal heat source were implemented in finite element simulation. As for an effect of geometric shape, the weld-induced deformation and residual stress should be taken into account during designing the welded structure. And for U-shape plates, the effect of curvature radius on the mechanical properties was also obtained, which is a significant factor affecting its service life. The simulation results revealed that the plate processed into U-shape could reduce the deformation and residual stress near the weld. And the deformation and residual stress in U-shape plate with circular arc transition were further reduced. Furthermore, the effect of curvature radius on the mechanical properties of plates was not general considered as the bigger curvature radius the better mechanical properties. The results concluded that the geometric shape significantly affects the mechanical properties, which provides prediction for structural design.

关键词： numerical simulation residual stress deformation processing shape

A New and Efficient Synthesis of 2H-3, 1-Benzoxazine Compounds

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2005年第11期16卷 1424-1426页

作者： Jia Rong LI Shu ling ma School of Chemical Engineering and Environment Beijing Institute of Technology Beijing 100081

2H-3, 1-Benzoxazine derivatives were synthesized by cyclocondensation of 5-nitro-2- cyanoaniline with relative ketone or aldehyde with ZnCl2 as a catalyst. This is a new efficient synthetic route of 2H-3, 1-benzoxazin... 详细信息

关键词： 2H-3 1-Benzoxazine cyclocondensation synthesis

Evaluating the Stability of Active manganese Sites During Electrochemical Reactions by Cyclic Voltammetry

在线全文

学校读者我要写书评

暂无评论

Transactions of Tianjin University 2022年第3期28卷 193-198页

作者： Ziang ma Jisi Li Tao ling Key Laboratory for Advanced Ceramics and machining Technology of Ministry of Education TianjinChina Key Laboratory of Composite and Functional materials School of Materials Science and EngineeringTianjin UniversityTianjin 300072China

manganese oxides are a promising class of electrocatalysts for renewable energy devices,such as fuel ***(Ⅲ) ions with e_(g) electron filling of-1 are the active sites for manganese-based ***,Mn(Ⅲ) sites may be disproportionated during electrochemical reactions,thus reducing the number of Mn(Ⅲ) active sites and decreasing the catalytic activity of manganese *** this work,we developed a facile cyclic voltammetry method to monitor the evolution of Mn(Ⅲ) sites on a series of manganese oxides under "working" *** proposed a descriptor S_(Mn(Ⅲ)) to describe the stability of Mn(Ⅲ).Our simulated and experimental results show that the higher is S_(Mn(Ⅲ)),the higher the active Mn(Ⅲ)density,and the higher the electrocatalytic activity of the manganese oxide electrocatalyst.

关键词： manganese oxides Mn(III)sites Cyclic voltammetry

Atomically precise Au_(25)(GSH)_(18)nanoclusters versus plasmonic Au nanocrystals:Evaluating charge impetus in solar water oxidation

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2023年第6期34卷 195-199页

作者： qiao-ling Mo Xiao-Cheng Dai Yang Xiao Fang-Xing Xiao College of materials Science and Engineering Fuzhou UniversityNew CampusMinhou 350108China Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350108China

Atomically precise metal nanoclusters(NCs)have been deemed as an emerging class of metal nanomaterials owing to fascinating size-dependent physicochemical properties,discrete energy band structure,and quantum confinement effect,which are distinct from conventional metal nanoparticles(NPs).Nevertheless,metal NCs suffer from photoinduced self-oxidative aggregation accompanied by in-situ transformation to metal NPs,markedly reducing the photosensitization of metal ***,maneuvering the generic instability of metal NCs,we perform the charge transport impetus comparison between atomically precise metal NCs and plasmonic metal NPs counterpart obtained from in-situ self-transformation of metal NCs in photoelectrochemical(PEC)water splitting *** conceptual demonstration,we proposed two quintessential heterostructures,which include TNTAs-Au_(25)heterostructure fabricated by electrostatically depositing glutathione(GSH)-protected Au_(25)(GSH)_(18)NCs on the TiO_(2)nanotube arrays(TNTAs)substrate,and TNTAs-Au heterostructure constructed by triggering self-transformation of Au_(25)(GSH)_(18)NCs to plasmonic Au NPs in TNTAs-Au_(25)via *** results indicate that photoelectrons produced over Au_(25)NCs are superior to hot electrons of plasmonic Au NPs in stimulating the interracial charge transport toward solar water *** is mainly ascribed to the significantly accelerated carrier transport kinetics,prolonged carrier lifespan,and substantial photosensitization effect of Au_(25)NCs compared with plasmonic Au NPs,resulting in the considerably enhanced PEC water splitting performance of TNTAs-Au_(25)relative to plasmonic TNTAs-Au counterpart under visible light *** work would provide important implications for rationally designing atomically precise metal NCsbased photosystems toward solar energy conversion.

关键词： Metal nanoclusters Surface Plasmon resonance Interfacial charge transfer Photoelectrochemical water splitting

Application of three-dimensional electron diffraction in structure determination of zeolites

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2024年第4期43卷 39-47页

作者： Yuhang Li Yang ling Yanhang ma School of Physical Science and Technology&Shanghai Key Laboratory of High-resolution Electron Microscopy ShanghaiTech UniversityShanghai201210China

Zeolites have received great attention due to their wide applications in various fields such as catalysis,adsorp-tion/separation,ion exchange,*** the atomic crystal structure of zeolites is crucial to understanding their functions and exploring their *** to the difficulty of synthesizing large single crystals,the structures of many zeolites cannot be solved using conventional single-crystal X-ray diffraction(SCXRD)***-dimensional electron diffraction(3D ED)has witnessed rapid development during the past decade and has shown its powerful ability in the structure determination of *** this review,we will briefly introduce the history of 3D ED and summarize recent advances in the application of 3D ED for the analysis of zeolite structures,along with several typical examples in this research field.

关键词： Electron diffraction Three-dimensional electron diffraction Zeolite Structure solution Electron crystallography