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Direct numerical simulation of hypersonic transition induced by an isolated cylindrical roughness element

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Science China(Physics,Mechanics & Astronomy) 2014年第12期57卷 2330-2345页

作者： DUAN zhi Wei XIAO zhi Xiang fu Song School of Aerospace Tsinghua University

Hypersonic boundary layer transition induced by an isolated cylindrical roughness element is investigated using direct numerical simulation method based on a finite volume *** simulate the transition procedure by resolving the generation and evolvement of small-scale coherent structures,and capture the shock wave at the same time,high-order minimum dispersion and controllable dissipation scheme is validated and then *** results are compared with the available measurements in the quiet wind tunnel,such as the dominated frequency and root mean square of *** computational dominated frequency of 19.23 k Hz is very close to the experimental one,21 k ***,the disturbances of the roughness are mostly generated by the"jet"just before the roughness,and then they travel and develop downstream with the shear layer and vortex *** transition is mainly dominated by the instabilities of both the horseshoe vortex and the shear layer.

关键词： hypersonic boundarry layer transtion roughness

Purification and Characterization of the Catalytic Domain of Protein Tyrosine Phosphatase SHP-1 and the Preparation of Anti-ΔSHP-1 Antibodies

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Chemical Research in Chinese Universities 2008年第5期24卷 592-596页

作者： LI Wan-nan ZHUANG Yan LI He SUN Ying fu Yao WU Xiao-xia ZHAO zhi-zhuang fu xue-qi Edmond H. Fischer Signal Transduction Laboratory College of Life Sciences Key Laboratory for Molecular Enzymology ＆ Engineering Ministry of Education dilin UniversilT Changchun 130021 P. R. China Department of Pathology The University of Oklahoma Health Science Center OK 73104 USA

This study is focused on the expression of an SH2 domain-truncated form of protein tyrosine phosphatase SHP-1（designated ΔSHP-1） and the preparation of its polyclonal antibodies. A cDNA fragment encoding ΔSHP-1 was amplified by PCR and then cloned into the pT7 expression vector. The recombinant pT7-ΔSHP-1 plasmid was used to transform Rosetta（DE3） E. coli cells. ΔSHP-1 was distributed in the exclusion body of E. coli cell extracts and was purified through a two-column chromatographic procedure. The purified enzyme exhibited an expected molecular weight on SDS-gels and HPLC gel filtration columns. It possesses robust tyrosine phosphatase activity and shows typical enzymatic characteristics of classic tyrosine phosphatases. To generate polyclonal anti-ΔSHP-1 antibodies, purified recombinant ΔSHP-1 was used to immunize a rabbit. The resultant anti-serum was subjected to purification on ΔSHP-1 antigen affinity chromatography. The purified polyclonal antibody displayed a high sensitivity and specificity toward ΔSHP-1. This study thus provides the essential materials for further investigating the biological function and pathological implication of SHP-1 and screening the inhibitors and activators of the enzyme for therapeutic drug development.

关键词： SHP-1 Protein tyrosine phosphatase Polyclonal antibodies

Topological phase transition in cavity optomechanical system with periodical modulation

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Chinese Physics B 2022年第7期31卷 104-111页

作者： zhi-Xu Zhang Lu Qi Wen-xue Cui Shou Zhang Hong-fu Wang Department of Physics College of ScienceYanbian UniversityYanji 133002China School of Physics Harbin Institute of TechnologyHarbin 150001China

We investigate the topological phase transition and the enhanced topological effect in a cavity optomechanical system with periodical *** calculating the steady-state equations of the system,the steady-state conditions of cavity fields and the restricted conditions of effective optomechanical couplings are *** is found that the cavity optomechanical system can be modulated to different topological Su–Schrieffer–Heeger(SSH)phases via designing the optomechanical couplings ***,combining the effective optomechanical couplings and the probability distributions of gap states,we reveal the topological phase transition between trivial SSH phase and nontrivial SSH phase via adjusting the decay rates of cavity ***,we find that the enhanced topological effect of gap states can be achieved by enlarging the size of system and adjusting the decay rates of cavity fields.

关键词： topological phase transition periodical modulation enhanced topological effect

Variational Principle for Topological Pressure on Subsets of Free Semigroup Actions

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Acta Mathematica Sinica,English Series 2021年第9期37卷 1401-1414页

作者： Xing fu ZHONG zhi Jing CHEN School of Mathematics and Statistics Guangdong University of Foreign StudiesGuangzhou 510006P.R.China School of Mathematics and Systems Science Guangdong Polytechnic Normal UniversityGuangzhou 510665P.R.China

We investigate the relations between Pesin–Pitskel topological pressure on an arbitrary subset and measure-theoretic pressure of Borel probability measures for finitely generated semigroup ***(X,G)be a system,where X is a compact metric space and G is a finite family of continuous maps on *** a continuous function f on X,we define Pesin–Pitskel topological pressure PG(Z,f)for any subset Z■X and measure-theoretical pressure Pμ,G(X,f)for anyμ∈M(X),where M(X)denotes the set of all Borel probability measures on *** any non-empty compact subset Z of X,we show that PG(Z,f)=sup{Pμ,G(X,f):μ∈M(X),μ(Z)=1}.

关键词： Topological pressure measure-theoretic pressure semigroup of continuous maps variational principle

Generalized dominance-based rough set approach to security evaluation with imprecise information

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High Technology Letters 2010年第3期16卷 254-262页

作者： Zhao Liang xue zhi School of Electronic and Electric Engineering Shanghai Jiaotong University Shanghai 200240 P.R. China

The model of grey multi-attribute group decision-making （MAGDM） is studied, in which the attribute values are grey numbers. Based on the generalized dominance-based rough set approach （G-DR- SA）, a synthetic security evaluation method is presented. With-the grey MAGDM security evaluation model as its foundation, the extension of technique for order performance by similarity to ideal solution （TOPSIS） integrates the evaluation of each decision-maker （DM） into a group＇s consensus and obtains the expected evaluation results of information system. Via the quality of sorting （QoS） of G-DRSA, the inherent information hidden in data is uncovered, and the security attribute weight and DMs＇ weight are rationally obtained. Taking the computer networks in a certain university as objects, the example illustrates that this method can effectively remove the bottleneck of the grey MAGDM model and has practical significance in the synthetic security evaluation.

关键词： security evaluation grey number multi-attribute group decision-making (MAGDM) generalized dominance-based rough set approach (G-DRSA)

Drag increment induced by a small-scale forward-facing step in Mach number5 turbulent boundary layer flows

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Chinese Journal of Aeronautics 2020年第10期33卷 2491-2498页

作者： Yifei xue Jie REN Jinling LUO Song fu School of Aerospace Engineering Tsinghua UniversityBeijing 100084China Department of Mechanical Engineering University of NottinghamNottingham NG72RDUnited Kingdom Beijing Aerospace Technology Institute Beijing 100074China

Small-scale roughness elements or imperfections are inevitable over the surface of a flight *** aerodynamics of these small-scale structures is difficult to predict but may play an important role in the design of a flight vehicle at high *** forward-facing step is a typical type of roughness *** experiments have been conducted to study the aerodynamics of supersonic forward-facing step,especially with a step height larger than boundary layer ***,few studies focus on small *** improve the understanding of small-scale forwardfacing step flow,we perform a series of simulations to analyze its aerodynamic influence on a Mach number 5 turbulent boundary *** general flow structures are analyzed and *** shock waves can be induced by the step even if the step height is much smaller than the boundary layer *** significant shocks are the separation shock and the reattachment *** influenced area by the step is *** the increase of the step height,the non-dimensional influence area decreases and gradually converges when the step height reaches the boundary layer *** are two normalized distributions of the skin friction coefficient and pressure coefficient associated with step *** using the normalized parameters,a power-law relationship between the step height and the drag increment coefficient is revealed and fits the simulation results *** is further illustrated that this relationship still holds when changing the inlet angle of attack,but needs slight modification with the angle of attack.

关键词： Aerodynamics Drag increment Forward-facing step Hypersonic flow Turbulent boundary layer

Y_5Si_3C and Y_3Si_2C_2: Theoretically predicted MAX phase like damage tolerant ceramics and promising interphase materials for SiC_f/SiC composites

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Journal of Materials Science & Technology 2019年第3期35卷 313-322页

作者： Yanchun Zhou Huimin Xiang fu-zhi Dai Science and Technology on Advanced functional Composite Laboratory Aerospace Research Institute of Materials & Processing Technology

Researching for interphase materials that can protect SiC fibers from oxygen and water vapor attacks has become one of the most important issues for the applications of SiC_f/SiC composites in high-temperature combustion environment. However, such kinds of interphase materials are not available yet. Herein,we report theoretically predicted properties of two promising interphase materials Y_5Si_3 C and Y_3Si_2C_*** crystallizing in different structures, they share the common features of layered structure,anisotropic chemical bonding, anisotropic electrical and mechanical properties, and low shear deformation resistance. The bulk moduli for Y_5Si_3C and Y_3Si_2C_2 are 78 and 93 GPa, respectively; while their shear moduli are 52 and 50GPa, respectively. The maximum to minimum Young's modulus ratios are1.44 for Y_5Si_3C and 3.27 for Y_3Si_2C_2. Based on the low shear deformation resistance and low Pugh's ratios(G/B = 0.666 forY_5Si_3C and 0.537 for Y_3Si_2C_2; G: shear modulus; B: bulk modulus), they are predicted as damage tolerant and soft ceramics with predicted Vickers hardness of 9.6 and 6.9 GPa, *** cleavage plane and possible slip systems are(000 l) and(0001)[1120] and(1010)[0001] forY_5Si_3C,and those for Y_3Si_2C_2 are {h00} and(010)[101]. Since the oxidation products are water-vapor resistant Y2 Si2 O7, Y2 SiO5 and/or Y_2 O_3 upon oxidation, and the volume expansions are ca 140% and ca 26% for Y_5Si_3C and Y_3Si_2C_2, they are expected to seal the interfacial cracks in SiC_f/SiC composites. The unique combination of easy cleavage, low shear deformation resistance, volume expansions upon oxidation, and the resistance of the oxidation products to water vapor attack warrant them promising as interphase materials of SiC_f/SiC composites for water-vapor laden environment applications.

关键词： Y5Si3C Y3Si2C2 Interphase material Damage tolerant ceramics Electronic structure

PRLs Promote Spreading, Adhesion, and Proliferation of Human SW480 and SW620 Cells

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Chemical Research in Chinese Universities 2006年第1期22卷 68-72页

作者： LI Zhao-fa XU xue-song SHEN Xing-gui LI Qing-shan ZHAO zhi-zhuang fu xue-qi LI Yu-lin LI Yi-lei Edmond H. Fischer Signal Transduction Laboratory College of Life Sciences Jilin University Changchun 130021 P. R. China China-Japan Union Hospital Jilin University Changchun 130031 P. R. China The Key Laboratory of Pathobiology Ministry of Education Jilin University Changchun 130023 P. R. China

Recent studies suggest that PRL-3 is involved in the metastasis of colorectal cancer, but the mechanism concerning that has not been well defined. This article expresses PRL-1, PRL-2, and PRL-3 and the catalytically inactive mutant forms of those enzymes in SW620 and SW480 cells, two human cell lines derived from non-metastatic cancer and metastatic colorectal cancer, respectively. While the expression of the native forms of PRLs promotes the spreading, adhesion, and proliferation of these cells, the expression of their mutant forms inhibits the earlier-mentioned processes. These data thus provide a cellular mechanism for the role of PRL-3 in tumor metastasis and suggest that all the three PRLs have similar functions.

关键词： PRL Metastasis Proliferation Expression SW480 cell SW620 cell

Enzyme-catalyzed Transesterification of Unusual Substrate: Synthesis of Acyclovir and L-ascorbic Acid (Vitamin C) Vinyl Esters

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Chinese Chemical Letters 2003年第2期14卷 163-166页

作者： Xing Tao xue De Shui Lu zhi Chun CHEN Qi WU Ying CAI Xian fu LIN Department of Chemistry Zhejiang UniversityHangzhou 310027

The synthesis of acyclovir and L-ascorbic acid with divinyladipate was performed with alkaline protease from Bacillus subtilis and lipase from Lipozyme (immobilized from Mucor miehei) in different anhydrous organic so... 详细信息

关键词： Alkaline protease lipase transesterification acyclovir vitamin C vinyl ester.