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Deformation heterogeneity of Ti under cryogenic channel-die compression

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Progress in Natural Science:Materials International 2011年第4期21卷 277-285页

作者： K.H.KIM S.K.HWANG division of Materials Science and engineering Inha University

Commercial purity Ti was subjected to channel die compression in liquid nitrogen for the purpose of studying its deformation characteristics from the viewpoint of the grain refinement induced by severe plastic *** specimens showed microstructural heterogeneity in that the initial blocky grains of about 50 urn in size turned into a mixture of the easily deforming soft grains and the hard grains revealing local concentration of dislocations and deformation *** electron back scattered diffraction analysis the in-grain misorientation-axis distribution was studied,from which it was found that the deformation heterogeneity resulted from the anisotropy of individual grains with respect to the compression die:while the soft grains were those oriented favorably for the prismslip,the hard ones were oriented for non-prism slips and deformation *** difference in the response of individual grains,therefore,led to a remarkable effect of the crystal texture of specimens on the maximum strain that can be imposed on specimens without *** on the present results,a way to achieve expedient grain refinement through the cryogenic plane-strain compression was suggested.

关键词： titanium cryogenic deformation texture microstructure

Optimizing the thickness of Ta_(2)O_(5) interfacial barrier layer to limit the oxidization of Ta ohmic interface and ZrO_(2) switching layer for multilevel data storage

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Journal of Materials Science & Technology 2022年第11期106卷 98-107页

作者： Muhammad Ismail Haider Abbas Chandreswar Mahata Changhwan Choi Sungjun Kim division of Electronics and Electrical engineering Dongguk UniversitySeoul 04620Republic of Korea division of Materials Science and engineering Hanyang UniversitySeoul 04763Republic of Korea

The multilevel storage capability of nonvolatile resistive random access memory(ReRAM)is greatly de-sired to accomplish high functioning memory *** this study,Ta_(2)O_(5) thin film with different thick-nesses(2,4,and 6 nm)was exploited as an appropriate interfacial barrier layer for limiting the formation of the interfacial layer between the 10 nm thick sputtering deposited resistive switching(RS)layer and Ta ohmic electrode to improve the switching cycle endurance and *** show that lower form-ing voltage,narrow distribution of SET-voltages,good dc switching cycles(10^(3)),high pulse endurance(10^(6) cycles),long retention time(10^(4) s at room temperature and 100℃),and reliable multilevel resis-tance states were obtained at an appropriate thickness of∼2 nm Ta_(2)O_(5) interfacial barrier layer instead of without Ta_(2)O_(5) and with∼4 nm,and∼6 nm Ta_(2)O_(5) barrier layer,ZrO_(2)-based memristive ***,multilevel resistance states have been scientifically investigated via modulating the compliance current(CC)and RESET-stop voltages,which displays that all of the resistance states were distinct and stayed stable without any considerable deprivation over 10^(4) s retention time and 104 pulse endurance *** I-V characteristics of RESET-stop voltage(from−1.7 to−2.3 V)of HRS are found to be a good linear fit with the Schottky *** can be seen that Schottky barrier height rises by increasing the stop-voltage during RESET-operation,resulting in enhancing the data storage memory window(on/offratio).Moreover,RESET-voltage and CC control of HRS and LRS revealed the physical origin of the RS mecha-nism,which entails the formation and rupture of conducting *** is thoroughly investigated that proper optimization of the barrier layer at the ohmic interface and the switching layer is essential in memristive *** results demonstrate that the ZrO_(2)-based memristive device with an optimized∼2 nm Ta_(2)O_(5) barrier

关键词： Resistive switching Ta_(2)O_(5)/ZrO_(2)bilayer film Barrier layer thickness Multilevel resistance states RESET-stop voltage

Computational Approaches for Prioritizing Candidate Disease Genes Based on PPI Networks

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Tsinghua Science and Technology 2015年第5期20卷 500-512页

作者： Wei Lan Jianxin Wang Min Li Wei Peng Fangxiang Wu the School of Information Science and engineering Central South University the Department of Mechanical engineering and division of Biomedical engineering University of Saskatchewan

With the continuing development and improvement of genome-wide techniques, a great number of candidate genes are discovered. How to identify the most likely disease genes among a large number of candidates becomes a fundamental challenge in human health. A common view is that genes related to a specific or similar disease tend to reside in the same neighbourhood of biomolecular networks. Recently, based on such observations,many methods have been developed to tackle this challenge. In this review, we firstly introduce the concept of disease genes, their properties, and available data for identifying them. Then we review the recent computational approaches for prioritizing candidate disease genes based on Protein-Protein Interaction（PPI） networks and investigate their advantages and disadvantages. Furthermore, some pieces of existing software and network resources are summarized. Finally, we discuss key issues in prioritizing candidate disease genes and point out some future research directions.

关键词： candidate disease-gene prioritization protein-protein interaction network human disease computational tools

Surface characteristics of chemical conversion coating for Mg-Al alloy

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中国有色金属学会会刊：英文版 2009年第4期19卷 892-897页

作者： Masazumi OKIDO Ryoichi ICHINO Seong-Jong KIM Seok-Ki JANG Nagoya University division of Marine engineering Mokpo Maritime University

The chemical conversion coating was formed on Mg alloy for low cost and harmlessness in environment by using the colloidal silica as the main *** film formed at 298 K was thick,which was thought to be the combination of Si and *** salt spray test,the ratio of black rust on the specimen that did not conducted chemical conversion treatment was five times or more than those of the chemical conversion treated *** film of chemical conversion coating produced by alkali treatment process was thinner than the specimen produced in basic chemical conversion treatment solution.

关键词：化学转化膜镁铝合金表面特性环境无害化盐雾试验涂膜厚度低成本硅溶胶

Influence of alkali metal doping on surface properties and catalytic activity/selectivity of CaO catalysts in oxidative coupling of methane

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Journal of Natural Gas Chemistry 2008年第4期17卷 313-320页

作者： V.H.Rane S.T.Chaudhari V.R.Choudhary Chemical engineering and Process Development division National Chemical Laboratory

Surface properties （viz. surface area, basicity/base strength distribution, and crystal phases） of alkali metal doped CaO （alkali metal/Ca= 0.1 and 0.4） catalysts and their catalytic activity/selectivity in oxidative coupling of methane （OCM） to higher hydrocarbons at different reaction conditions （viz. temperature, 700 and 750 ℃; CH4/O2 ratio, 4.0 and 8.0 and space velocity, 5140-20550 cm^3 ·g^-1·h^-1） have been investigated. The influence of catalyst calcination temperature on the activity/selectivity has also been investigated. The surface properties （viz. surface area, basicity/base strength distribution） and catalytic activity/selectivity of the alkali metal doped CaO catalysts are strongly influenced by the alkali metal promoter and its concentration in the alkali metal doped CaO catalysts. An addition of alkali metal promoter to CaO results in a large decrease in the surface area but a large increase in the surface basicity （strong basic sites） and the C2＋ selectivity and yield of the catalysts in the OCM process. The activity and selectivity are strongly influenced by the catalyst calcination temperature. No direct relationship between surface basicity and catalytic activity/selectivity has been observed. Among the alkali metal doped CaO catalysts, Na-CaO （Na/Ca = 0.1, before calcination） catalyst （calcined at 750 ℃）, showed best performance （C2＋ selectivity of 68.8% with 24.7% methane conversion）, whereas the poorest performance was shown by the Rb-CaO catalyst in the OCM process.

关键词： oxidative coupling of methane alkali metal doped CaO catalysts basicity/base strength distribution catalytic activity/selectivity

Optimal Design of Splitters Attached to Turbo Blower Impeller by RSM

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Journal of Thermal Science 2012年第3期21卷 215-222页

作者： Choon-Man Jang Ka-Ram Choi Environmental engineering Research division Korea Institute of Construction Technology

This paper describes the optimization of the impeller having splitters for a turbo *** design variables,chord of splitter and pitch of splitter,are introduced to enhance the blower *** pressure and ef-ficiency are selected as an object function,and the optimization of the blower impeller is performed by a response surface method (RSM).Three-dimensional Navier-Stokes equations are introduced to analyze the internal flow of the blower and to find the value of the object function for each *** the shape optimization of the splitters attached to the impeller in the turbo blower,pressure and efficiency at the design flow condition are suc-cessively increased by 5.9 percent and 17.9 percent respectively based on the reference *** higher blower efficiency obtained by optimization of impeller having splitters is mainly caused by reducing the number of im-peller blades and optimal design of splitters in the blade passage while pressure increase keeps almost the same with the reference *** the object function of pressure,pressure increase is obtained at the design and off-design conditions while efficiency keeps higher compared to the reference *** enhancement of blow-er performance is due to the reduction of reverse and circulation flows in the blade passage.

关键词： Turbo Blower Splitter Numerical Simulation Optimal Design Pressure Response Surface Method

Review:Advances in research of stress-assisted corrosion fatigue problem

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Journal of Zhejiang University-Science A(Applied Physics & engineering) 2007年第2期8卷 221-227页

作者： TANG Zhi-bo LI Qiang division of engineering Zhejiang Ocean University Zhoushan 316004 China

Ceramic materials are notable for their rigidity, insulation and resistance to hostile environment, Nevertheless, if a stressed ceramic component is exposed to chemical attack, it may suffer from a form of delayed fracture known as static fatigue. From the point of view of a designer, it is clearly desirable to determine the behavior of sub-critical crack growth; the crack path and crack growth rate, as a function of material properties and loading conditions are of particular interest. This paper presents a review of advances in stress assisted corrosion problem in history and its corresponding numerical approaches in the last decades, and finally, comes uo with consideration and crucial suggestions for future work.

关键词： Stress corrosion Finite element method (FEM) Fracture Static fatigue Meshless local Petrov-Galerkin (MLPG)

3D biofabrication of vascular networks for tissue regeneration:A report on recent advances

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Journal of Pharmaceutical Analysis 2018年第5期8卷 277-296页

作者： M.D.Sarker Saman Naghieh N.K.Sharma Xiongbiao Chen division of Biomedical engineering College of Engineering University of Saskatchewan Department of Mechanical engineering College of Engineering University of Saskatchewan

Rapid progress in tissue engineering research in past decades has opened up vast possibilities to tackle the challenges of generating tissues or organs that mimic native structures. The success of tissue engineered constructs largely depends on the incorporation of a stable vascular network that eventually anastomoses with the host vasculature to support the various biological functions of embedded cells. In recent years, significant progress has been achieved with respect to extrusion, laser, micro-molding, and electrospinning-based techniques that allow the fabrication of any geometry in a layer-by-layer fashion. Moreover, decellularized matrix, self-assembled structures, and cell sheets have been explored to replace the biopolymers needed for scaffold fabrication. While the techniques have evolved to create specific tissues or organs with outstanding geometric precision, formation of interconnected, functional, and perfused vascular networks remains a challenge. This article briefly reviews recent progress in 3D fabrication approaches used to fabricate vascular networks with incorporated cells, angiogenic factors, proteins, and/or peptides. The influence of the fabricated network on blood vessel formation, and the various features, merits, and shortcomings of the various fabrication techniques are discussed and summarized.

关键词： 3D bioprinting Tissue engineering Vascularization Extrusion Laser-based printing Co-axial printing

Effects of Ni doping on the structural properties and collapse of magnetic ordering in NdFe_(1-x)Ni_xO_3(0.1 ≤x≤ 0.7) orthoferrites

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Chinese Physics B 2016年第2期25卷 496-503页

作者： I.Ahmad M.J.Akhtar M.Siddique Department of Metallurgy and Materials engineering PIEAS Physics division PINSTECH

Nd Fe_（1-x）Ni_xO_3（0.1 ≤ x ≤ 0.7） orthoferrites are synthesized by solid state reaction method, and the structural properties of these materials are investigated by employing x-ray diffraction（XRD）, scanning electron microscopy（SEM） and M o¨ssbauer spectroscopy. The orthorhombic structure is observed in all systems; however, with the increase in Ni doping,the increase in tolerance factor and the decrease in the cell volume are observed. Orthorhombic distortion decreases with Ni content increasing up to 50%, while above 50% Ni doping it increases. SEM examination indicates the increases in grain size and intermixing of grains with increase in Ni concentration. Comparison between bulk and theoretical densities shows that in each of all samples porosity is less than 2%. M？ssbauer spectroscopic investigations are performed to explain local structure, Fe oxidation states and collapse of the magnetic ordering. In these samples the Fe oxidation state remains＋3 and there is no considerable increase in hole states observed; however due to mismatch of the ionic radii between Fe^（3＋） and Ni^（3＋）, octahedral distortions, sagging and distribution of hyperfine parameters increase with increase in Ni concentration. The major factors behind the collapse of magnetic ordering in the Ni-doped systems are the weakening of the super-exchange interactions, decrease in the Neel temperature, increase in spin–spin relaxation frequency and high spin to low spin transition.

关键词： ceramic crystal structure electron microscopy Mossbauer spectroscopy