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Enhancement of Sinter Densification of SrO-BaO-Nb_2O_5-SiO_2 Tungsten-Bronze Glass-ceramics by Doping with P_2O_5

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Journal of Materials Science & Technology 2013年第8期29卷 731-736页

作者： J.c.chen Y.Zhang Shenyang Research and Development centre for Advanced Materials Institute of Metal ResearchChinese Academy of Sciences State Key Laboratory of New ceramics and Fine Processing Institute of Nuclear and New Energy TechnologyTsinghua University

Densification behaviors of SrO-BaO-Nb2O5-SiO2 based glass-ceramics prepared by conventional sintering were investigated with an emphasis on the influence of P2O5 content. Although P2O5 dopant did not modify the surface crystallization mechanism, it resulted in a decrease of the glass transition temperature, which facilitates the viscous glass flow necessary for sintering. However, premature crystallization of （Sr, Ba）Nb2O6 induced by addition of excess amount of P2O5 essentially retarded sintering due to the formation of closed pores in the matrix. The SrO-BaO-Nb2O5-SiO2 glass with 1.0 mol% P2O5 （SBN-1P） showed the best sinter densification, which was accomplished at about 850 ℃.

关键词： Sintering densification DieLectric properties Glass-ceramic

Reactive wetting behaviors of Sn/cu systems: A molecular dynamics study

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Nano-Micro Letters 2010年第2期2卷 60-67页

作者： J.Y.Hsieh J.L.chen c.chen H.c.Lin S.S.Yang c.c.Hwang Department of Mechanical Engineering Ming Hsin University of Science and Technology Institute of Precision Mechatronic Engineering Ming Hsin University of Science and Technology Department of Mechanical Engineering Wu Feng Institute of Technology Department of Information Management Meiho Institute of Technology Department of Engineering Science National Cheng Kung University

Influences of temperature and Sn-cu droplet's composition on reactive wettings of cu(100), cu(110), and cu(111) surfaces were analyzed, by using molecular dynamics(MD) calculations. As a result, the spreading on cu(110)(cu(100)) has the fastest(slowest) wetting kinetics. A higher temperature or a diluter cu content in the Sn-cu alloy droplet results in a higher wettability. Moreover, this work has addressed a theory for positioning the interface separating the liquidus and solidus alloys in the spreading film to confirm the hypothesis that the reactive wetting will come to the end when the interface saturates with the temperature-dependent solidus weight fraction of cu.

关键词： Wetting Surface alloying Molecular dynamics Droplet

A new localization theory of adaptive machining of near-net-shape blades

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chinese Journal of Aeronautics 2021年第6期34卷 18-32页

作者： Neng WAN Xiaogang SHEN Zhiyong cHANG Zezhong c.chen Department of Mechanical Engineering Northwestern Polytechnical UniversityXi'an 710072China Department of Mechanical Industrial and Aerospace EngineeringConcordia UniversityMontrealQuebec H3G IMSCanada

In the fabrication of aero-engine blades,a great deal is gained when massive material removal is avoided at the end of the process,and as little as possible material is left on the blade *** to the uncertainty of pre-process,the billet shapes are ***,the near-net-shape billet doesn’t cover the blade design surface to be ***,blade localization is necessary for these billets before the *** conventional localization methods,the design surface’s location focused on guaranteeing enough material to be ***,because the to-becut surface is in near-net and free-form shape,it is difficult to find a valid localized surface model to generate the tool *** from the localized surface is taken as rigid in previous investigation,it is allowed to deviate from the design surface no more than the tolerance *** term of this principle,the tolerance band is utilized to promote localization ability.A series of optimization models with different priorities is established to avoid the abandonment expensive blade ***,with the experiments performed on the near-net-shape blades,the blade localization theory and the promotion of localization ability are verified.

关键词： Blade localization curvature constraint Machining surface Near-net-shape blade Tolerance constraint

Reduced non-cpG methylation is a potential epigenetic target after spinal cord injury

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Neural Regeneration Research 2023年第11期18卷 2489-2496页

作者： Zhourui Wu chen Li Ran Zhu Yiqiu cao Thomas c.chen Liming cheng Key Laboratory of Spine and Spinal cord Injury Repair and Regeneration(Tongji University) Ministry of EducationShanghaiChina Division of Spine Department of OrthopedicsTongji HospitalTongji University School of MedicineShanghaiChina Institute of Spinal and Spinal cord Injury Tongji University School of MedicineShanghaiChina Department of Neurosurgery Keck School of MedicalUniversity of Southern CaliforniaLos AngelesCAUSA

DNA methylation is a critical epigenetic regulator in the occurrence and development of diseases and is closely related to various functional responses in relation to spinal cord *** investigate the role of DNA methylation in spinal cord injury,we constructed a library with reduced-representation bisulfite sequencing data obtained at various time points(day 0-42)after spinal cord injury in *** DNA methylation levels,specifically non-cpG(cHG and cHH)methylation levels,decreased modestly following spinal cord *** post-spinal cord injury were classified as early(day 0-3),intermediate(day7-14),and late(day 28-42)based on similarity and hie rarchical cluste ring of global DNA methylation *** non-cpG methylation level,which included cHG and cHH methylation levels,was markedly reduced despite accounting for a minor proportion of total methylation *** multiple genomic sites,including the 5’untranslated regions,promoter,exon,intron,and 3’untranslated regions,the non-cpG methylation level was markedly decreased following spinal cord injury,whereas the cpG methylation level remained unchanged at these *** one-half of the differentially methylated regions were located in intergenic areas;the other differentially methylated regions in both cpG and non-cpG regions were cluste red in intron regions,where the DNA methylation level was *** function of genes associated with differentially methylated regions in promoter regions was also *** Gene Ontology analysis results,DNA methylation was implicated in a number of essential functional responses to spinal cord injury,including neuronal synaptic connection creation and axon ***,neither cpG methylation nor non-cpG methylation was implicated in the functional response of glial or inflammatory *** summary,our work elucidated the dynamic pattern of DNA methylation in the spinal co rd following injury and identified reduced noncpG meth

关键词： cpG methylation cytosine fraction differentially methylated regions DNA methylation DNA methyltransferases dynamic signatures Gene Ontology non-cpG methylation single-cell RNA-Seq spinal cord injury

The Numerical Analysis of Strain Behavior at Solder Joint and Interface of Flip chip Package

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厦门大学学报（自然科学版） 2002年第S1期41卷 186-188页

作者： S c chen Y c Lin Department of Mechatronics Engineering National Changhua University of EducationDepartment of Mechatronics EngineeringNational Changhua University of Education Changhua 50058 Taiwan ChinaChanghua 50058 Taiwan China

The flip chip package is a kind of advanced electri ca l packages. Due to the requirement of miniaturization, lower weight, higher dens ity and higher performance in the advanced electric package, it is expected that flip chip package will soon be a mainstream technology. The silicon chip is dir ectly connected to printing circuit substrate by SnPb solder joints. Also, the u nderfill, a composite of polymer and silica particles, is filled in the gap betw een the chip and substrate around the solder joints to improve the reliabili ty of solder joints. When flip chip package specimen is tested with thermal cycl ing, the cyclic stress/strain response that exists at the underfill interfaces and solder joints may result in interfacial crack initiation and propagation. Therefore, the chip cracking and the interfacial delamination between underfill and chip corner have been investigated in many studies. Also, most researches h ave focused on the effect of fatigue and creep properties of solder joint induce d by the plastic strain alternation and accumulation. The nuderfill must have lo w viscosity in the liquid state and good adhesion to the interface after solidif ying. Also, the mechanical behavior of such epoxy material has much dependen ce on temperature in its glass transition temperature range that is usually cove red by the temperature range of thermal cycling test. Therefore, the materia l behavior of underfill exists a significant non-linearity and the assumption o f linear elastic can lack for accuracy in numerical analysis. Through numerical analysis, this study had some comparisons about the effect of linear and non -linear properties of underfill on strain behaviors around the interface of fli p chip assembly. Especially, the deformation tendency inside solder bumps could be predicted. Also, it is worthily mentioned that we have pointed out which comp onent of plastic strain, thus, either normal or shear, has dominant influence to the fatigue and creep of sold

关键词： The Numerical Analysis of Strain Behavior at Solder Joint and Interface of Flip chip Package

An automated approach to calculating the maximum diameters of multiple cutters and their paths for sectional milling of centrifugal impellers on a 4_(1/2)-axis cNc machine

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chinese Journal of Aeronautics 2019年第4期32卷 1030-1039页

作者： Baohai WU Zezhong c.chen Ming LUO Dinghua ZHANG Feiyan HAN School of Mechanical Engineering Northwestern Polytechnical University Department of Mechanical Industrial and Aerospace EngineeringConcordia University college of Mechanical Engineering Xi'an University of Science and Technology

Power generators and chemical engineering compressors include heavy and large centrifugal impellers. To produce these impellers in high-speed machining, a 4?-axis milling machine(or a 4-axis machine plus an indexing table) is often used in the industry, which is more rigid than a5-axis milling machine. Since impeller blades are designed with complex B-spline surfaces and impeller channels spaces vary significantly, it is more efficient to use multiple cutters as large as possible to cut a channel in sections and a blade surface in patches, instead of only using a small cutter to machine a whole blade and a channel. Unfortunately, no approach has been established to automatically calculate the largest diameters of cutters and their paths, which include the indexing table angles. To address this problem, an automated and optimization approach is proposed. Based on the structure of a 4?-axis machine, a geometric model for a cutter gouging/interfering the impeller is formulated, and an optimization model of the cutter diameter in terms of the indexing table angle is established at a cutter contact(cc) point on a blade surface. Then, the diameters of the tools,their orientations, and the indexing table angles are optimized, and each tool's paths are generated for machining its corresponding impeller section. As a test, an impeller is efficiently machined with these tools section by section; thus, this approach is valid. It can be directly used in the industry to improve efficiency of machining centrifugal impellers.

关键词： Automated path generation 4_(1/2)-Axis cNc machining centrifugal impeller machining cutter diameter optimization Sectional machining

A Practical Predefined-Time Stability criterion and Its Application to Uncertain Nonlinear Systems

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Journal of Systems Science & complexity 2024年第6期37卷 2556-2578页

作者： XU Hao YU Dengxiu SUI Shuai XU Bowen chen c.L.Philip Unmanned System Research Institute Northwestern Polytechnical UniversityXi'an 710072China college of Science Liaoning University of TechnologyJinzhou 121001China School of Artificial Intelligence Optics and ElectronicsNorthwestern Polytechnical UniversityXi'an 710072China School of computer Science and Engineering South China University of Technology and Pazhou LabGuangzhou 510641China

In this paper,the singularity-free predefined-time fuzzy adaptive tracking control problem is studied for non-strict feedback(NSF)nonlinear systems considering mismatched external *** innovative practical predefined-time stability(PPTS)criterion is proposed to provide the theoretical basis for subsequent control *** to the existing predefined-time stability(PTS)criterion,this criterion has a broader application range and can solve the control design issues of nonlinear systems with system *** logic systems(FLSs)are employed to identify unknown nonlinear *** on the backstepping control technology,a singularity-free predefined-time control(PTc)design method is proposed,in which the hyperbolic tangent function is utilized to avoid the singular problem,and the nature of fuzzy basis function is adopted to resolve the algebraic loop *** PPTS of the closed-loop NSF nonlinear system is proven with the Lyapunov theory and the proposed PPTS ***,the efficiency of the presented PTc design method is verified by several sets of simulations on a single link manipulator system.

关键词： Fuzzy adaptive control nonlinear systems practical predefined-time stability predefinedtime control singularity-free control

Nanoscale strain engineering of graphene and graphene-based devices

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Acta Mechanica Sinica 2016年第3期32卷 497-509页

作者： N.-c.Yeh c.-c.Hsu M.L.Teague J.-Q.Wang D.A.Boyd c.-c.chen Department of Physics Institute for Quantum Information and Matter and Kavli Nanoscience InstituteCalifornia Institute of Technology Department of Physics Fudan University Department of Physics California Institute of Technology

Structural distortions in nano-materials can induce dramatic changes in their electronic properties. This situation is well manifested in graphene, a two-dimensional honeycomb structure of carbon atoms with only one atomic layer thickness. In particular, strained graphene can result in both charging effects and pseudo-magnetic fields, so that controlled strain on a perfect graphene lattice can be tailored to yield desirable electronic properties. Here, we describe the theoretical foundation for strain-engineering of the electronic properties of graphene, and then provide experimental evidence for strain-induced pseudo-magnetic fields and charging effects in monolayer graphene. We further demonstrate the feasibility of nano-scale strain engineering for graphene-based devices by means of theoretical simulations and nano-fabrication technology.

关键词： Graphene Strain-engineering Nanostructures Dirac fermions Pseudo-magnetic field Valleytronics

Insights on the use of biosimilars in the treatment of inflammatory bowel disease

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World Journal of Gastroenterology 2017年第11期23卷 1932-1943页

作者： Michael K Zheng David Q Shih Gary c chen F.Widjaja Foundation Inflammatory Bowel and Immunobiology Research InstituteCedars-Sinai Medical Center comprehensive Digestive Institute of Nevada

Biologic therapy, such as those that target tumor necrosis factor(TNF) signaling, has proven to be an efficacious method of treatment for patients with inflammatory bowel disease(IBD) with regards to symptom management and mucosal healing. However, the rising prevalence of IBD worldwide and the everincreasing burden of biologic pharmaceuticals in the health care industry is alarming for insurance companies, clinicians, and patients. The impending patent expiry and the relatively high costs of biologics, particularly anti-TNF agents, have paved the way for biosimilar development for IBD. The United States Food and Drug Administration defines a biosimilar as a biological product that is highly similar to its reference medicinal product, with no clinically meaningful differences in terms of safety, purity, and potency. The hope with biosimilars is that their entry into the market will be able to drive competition between pharmaceutical companies to reduce prices like that of the generic market, and that access to appropriate biologic treatments for IBD patients is increased in the long-term. Yet, there are challenging issues such as indication extrapolation and interchangeability that are still being debated in the field of IBD and must be addressed in future issued guidance. This review will discuss the issues and implications concerning the use of biosimilar therapy for IBD.

关键词： Biosimilar Biologic Inflammatory bowel disease Ulcerative colitis crohn’s disease Indication extrapolation Interchangeability