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Search Results: 1 - 10 of 49591 matches for " GUAN Yi-xin "
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Matrix models of 4-dimensional quantum Hall fluids
Yi-Xin Chen
Physics , 2002,
Abstract: We propose two non-abelian Chern-Simons matrix models as the effective descriptions of 4-dimensional quantum Hall fluids. One of them describes a new type of 4-dimensional quantum Hall fluid on the space of quaternions, the other provides the description of non-commutative field theory for Zhang and Hu's 4-dimensional quantum Hall fluid of $S^4$. The complete sets of physical quantum states of these matrix models are determined, and the properties of quantum Hall fluids related with them are discussed.
Rigid open membrane and non-abelian non-commutative Chern-Simons theory
Yi-Xin Chen
Physics , 2002,
Abstract: In the Berkooz-Douglas matrix model of M theory in the presence of longitudinal $M5$-brane, we investigate the effective dynamics of the system by considering the longitudinal $M5$-brane as the background and the spherical $M5$-brane related with the other space dimensions as the probe brane. Due to there exists the background field strength provided by the source of the longitudinal $M5$-brane, an open membrane should be ended on the spherical $M5$-brane based on the topological reason. The formation of the bound brane configuration for the open membrane ending on the 5-branes in the background of longitudinal 5-brane can be used to model the 4-dimensional quantum Hall system proposed recently by Zhang and Hu. The description of the excitations of the quantum Hall soliton brane configuration is established by investigating the fluctuations of $D0$-branes living on the bound brane around their classical solution derived by the transformations of area preserving diffeomorphisms of the open membrane. We find that this effective field theory for the fluctuations is an SO(4) non-commutative Chern-Simons field theory. The matrix regularized version of this effective field theory is given in order to allow the finite $D0$-branes to live on the bound brane. We also discuss some possible applications of our results to the related topics in M-theory and to the 4-dimensional quantum Hall system.
Quantum Measured Information
Yi-Xin Chen
Physics , 1999,
Abstract: A framework for a quantum information theory is introduced that is based on the measure of quantum information associated with probability distribution predicted by quantum measuring of state. The entanglement between states of measured system and "pointer" states of measuring apparatus, which is generated by dynamical process of quantum measurement, plays a dominant role in expressing quantum characteristics of information theory. The quantum mutual information of transmission and reception of quantum states along a noisy quantum channel is given by the change of quantum measured information. In our approach, it is not necessary to purify the transmitted state by means of the reference system. It is also clarified that there exist relations between the approach given in this letter and those given by other authors.
Quasiparticle excitations and hierarchies of 4-dimensional quantum Hall fluid states in the matrix models
Yi-Xin Chen
Physics , 2002,
Abstract: We investigate the condensate mechanism of the low-lying excitations in the matrix models of 4-dimensional quantum Hall fluids recently proposed by us. It is shown that there exist some hierarchies of 4-dimensional quantum Hall fluid states in the matrix models, and they are similar to the Haldane's hierarchy in the 2-dimensional quantum Hall fluids. However, these hierarchical fluid states appear consistently in our matrix models without any requirement of modifications of the matrix models.
Study on Disulfide Bond Formation Protein A in Escherichia coli
大肠杆菌二硫键形成蛋白A(DsbA)研究进展

LUO Man,GUAN Yi-Xin,YAO Shan-Jing,
罗曼
,关怡新,姚善泾

生物工程学报 , 2007,
Abstract: Disulfide bond formation protein A, DsbA, is one of the important proteins located in E. coli periplasm, which is a foldase facilitating the folding of nascent secreted proteins, especially for those with many pairs of disulfide bonds. The crystal structure and phylogenetic analysis of DsbA and DsbA-mediated protein folding, alternatively in vivo and in vitro, are summarized. Both the extremely low pK_a of Cys~ 30 , about 3.5, and the destabilizing effect of the active site disulfide contribute to its strong oxidizing power. The Cys~ 30 is also considered as the most important residue closely related to its activity using site-directed mutagenesis methodology. DsbA could effectively assist proteins folding, both in vivo coexpressed with the target protein, and in vitro replenished as foldases. Moreover, DsbA also has the chaperone-like activity in the assistant refolding of genetically engineered inclusion bodies.
Study on Disulfide Bond Formation Protein A in Escherichia coli
大肠杆菌二硫键形成蛋白A(DsbA)研究进展

LUO Man,GUAN Yi-Xin,YAO Shan-Jing,
罗曼
,关怡新,姚善泾

微生物学报 , 2007,
Abstract: Disulfide bond formation protein A, DsbA, is one of the important proteins located in E. coli periplasm, which is a foldase facilitating the folding of nascent secreted proteins, especially for those with many pairs of disulfide bonds. The crystal structure and phylogenetic analysis of DsbA and DsbA-mediated protein folding, alternatively in vivo and in vitro, are summarized. Both the extremely low pKa of Cys30, about 3.5, and the destabilizing effect of the active site disulfide contribute to its strong oxidizing power. The Cys30is also considered as the most important residue closely related to its activity using site-directed mutagenesis methodology. DsbA could effectively assist proteins folding, both in vivo coexpressed with the target protein, and in vivo replenished as foldases. Moreover, DsbA also has the chaperone-like activity in the assistant refolding of genetically engineered inclusion bodies.
Formation of dimers in refolding of recombinant human interferon-γ by ion-exchange chromatography
离子交换层析复性重组人γ-干扰素折叠二聚体的形成

JIN Ting,GUAN Yi-xin,YAO Shan-jing,
靳挺
,关怡新,姚善泾

浙江大学学报(农业与生命科学版) , 2006,
Abstract: SP Sepharose Fast Flow离子交换层析柱作为蛋白质复性系统,采用尿素梯度法进行重组人γ-干扰素包涵体蛋白质的复性实验.结果表明,尿素梯度离子交换层析法能有效地复性重组人γ-干扰素包涵体,复性后的重组人γ-干扰素的纯度达95%,蛋白收率达54%,比活为7.5×105IU?mg-1.以Superdex 75凝胶作为体积排阻层析介质,对离子交换层析复性的样品进行分析,表明离子交换层析复性的样品中没有重组人γ-干扰素聚集体存在.荧光光谱分析表明重折叠的重组人γ-干扰素的构象接近于其天然二聚体构象.
An image analysis method for quantification of hepatic perfusion based on contrast-enhanced ultrasound imaging  [PDF]
Yi-xin Li, Fang Yang, Ning Gu
Journal of Biomedical Science and Engineering (JBiSE) , 2008, DOI: 10.4236/jbise.2008.12019
Abstract: Information about hepatic perfusion is used in clinical liver disease diagnosis. An image analy-sis system can help physicians make efficient and accurate diagnosis. The objective of this study is to propose an image analysis method for the quantification of the hepatic perfusion based on contrast-enhanced ultrasound imaging (CEUI). The proposed method contains frame selection, image registration, digital subtraction and grey-scale calculation. Then, by processing an image sequence, a time-intensity curve (TIC) for hepatic perfusion is derived. The kernel of this image analysis technology is digital subtrac-tion and its accuracy is improved by frame selec-tion and image registration. The advantage of this method is that it can obtain the perfusion information of the whole liver which is rarely ob-tained by traditional image analysis technology; therefore, it is a supplement of the traditional image analysis method. This method is applied on the quantification of a rabbit’s hepatic perfu-sion and the result shows the efficiency of it.
A Colorimetric Method to Assay Biological Activity of Recombinant Human IFN-γ
重组人γ干扰素复性过程中体外活性检测方法研究*

FEI Zheng-Zheng GUAN Yi-Xin YAO Shan-Jing,
费峥峥
,关怡新,姚善泾

微生物学通报 , 2004,
Abstract: 结晶紫染色法由于具有客观、精确的特点,适用于大量抗肿瘤药物的药敏测定。本实验对此方法进行了探讨和条件优化,考察了结晶紫染液的用量及作用时间、溶媒提取时间、孔板效应及边缘效应等,并将其应用于重组人γ干扰素包涵体初步复性的体外活性检测之中。
Hydroxylation of 16α, 17α-epoxy-4-pregenene-3,20-dione by Absidia coerulea with Pseudo-crystallo Feed
拟结晶投料环氧黄体酮犁头霉羟化过程研究

WANG Jia,GUAN Yi-Xin,WANG Hai-Qing,YAO Shan-Jing,
王嘉
,关怡新,王海清,姚善泾

生物工程学报 , 2006,
Abstract: The 11-hydroxylation of 16alpha,17alpha-epoxy-4-pregenene-3,20-dione as a useful intermediate for the preparation of hormones can be achieved by the mycelium of Absidia coerulea at higher conversion rate than using other strains. In this paper 16alpha,17alpha-epoxy-4-pregenene-3,20-dione mixed with a little water, beta-cyclodextrin, Tween-80 was introduced into the fermentation broth after ultrasonication to increase pseudo-water-solubility of the hydrophobic substrate. This pseudo-crystallo feed could avoid the toxicity of organic solvents and was more available for the microbial transformation. The multi layer feed-forward neural network was used to setup a model which indicated the relationship between medium and feed components and the conversion rate. Particle swarm optimization (PSO), which was a stochastic global optimization algorithm and of which the convergence speed was high, was applied to obtain the optimal concentration of the medium and feed components. At optimum conditions with the pseudo-crystallo feed, the conversion rate of 16alpha,17alpha-epoxy-4-pregenene-3,20-dione at an initial concentration of 10 g/L was 87.5% in shaking flasks. The conversion rate of the substrate was up to 86.6% at higher concentration of 20 g/L feed in a 3.7 L fermentor.
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