聚乙二醇修饰物混合曲拉通X100-硫酸盐-液-固萃取体系分离纯化基因重组蛋白的可行性研究

以工程菌中被绿色荧光蛋白修饰的基因重组蛋白为对象,构建了聚乙二醇天冬氨酸修饰物PEG-ASP-Cu(Ⅱ)混合曲拉通X-100-硫酸盐-水液-固萃取体系纯化该融合蛋白.探讨了在体系中适用的表征目标蛋白的荧光方法,通过实验确定了采用恒波长同步荧光法测定日标蛋白质,可排除萃取体系中其他因素,尤其曲拉通X-100对目标蛋白测定的影响,得出最件测定条件.通过验证可知该萃取体系对目标蛋白最佳正萃分离条件和最佳反萃条件.结果表明:未加入修饰物的单纯液-固萃取体系对目标蛋白萃取固相收得率在50％～89％;加入修饰物后,体系对目标蛋白的一次萃取固相收得率提升并稳定在97％以上,最高达100％,一次反萃取率达68％.     

Bankruptcy prediction using a discrete‐time duration model incorporating temporal and macroeconomic dependencies

The purpose of this paper is to build an alternative method of bankruptcy prediction that accounts for some deficiencies in previous approaches that resulted in poor out‐of‐sample performances. Most of the traditional approaches suffer from restrictive presumptions and structural limitations and fail to reflect the panel properties of financial statements and/or the common macroeconomic influence. Extending the work of Shumway (2001), we present a duration model with time‐varying covariates and a baseline hazard function incorporating macroeconomic dependencies. Using the proposed model, we investigate how the hazard rates of listed companies in the Korea Stock Exchange (KSE) are affected by changes in the macroeconomic environment and by time‐varying covariate vectors that show unique financial characteristics of each company. We also investigate out‐of‐sample forecasting performances of the suggested model and demonstrate improvements produced by allowing temporal and macroeconomic dependencies. Copyright © 2008 John Wiley & Sons, Ltd.     

SPIN90 dephosphorylation is required for cofilin-mediated actin depolymerization in NMDA-stimulated hippocampal neurons

Actin plays a fundamental role in the regulation of spine morphology (both shrinkage and enlargement) upon synaptic activation. In particular, actin depolymerization is crucial for the spine shrinkage in NMDAR-mediated synaptic depression. Here, we define the role of SPIN90 phosphorylation/dephosphorylation in regulating actin depolymerization via modulation of cofilin activity. When neurons were treated with NMDA, SPIN90 was dephosphorylated by STEP61 (striatal-enriched protein tyrosine phosphatase) and translocated from the spines to the dendritic shafts. In addition, phosphorylated SPIN90 bound cofilin and then inhibited cofilin activity, suggesting that SPIN90 dephosphorylation is a prerequisite step for releasing cofilin so that cofilin can adequately sever actin filaments into monomeric form. We found that SPIN90 YE, a phosphomimetic mutant, remained in the spines after NMDAR activation where it bound cofilin, thereby effectively preventing actin depolymerization. This led to inhibition of the activity-dependent redistribution of cortactin and drebrin A, as well as of the morphological changes in the spines that underlie synaptic plasticity. These findings indicate that NMDA-induced SPIN90 dephosphorylation and translocation initiates cofilin-mediated actin dynamics and spine shrinkage within dendritic spines, thereby modulating synaptic activity.     

沥青路面早期破坏原因的浅探

文章从路面设计、路面施工、养护管理及其他环节,结合本人的工程实践,分析了沥青路面早期破坏的原因.     

运用用户满意策略实施政府机构改革

用户满意的概念源于全面质量管理,这是一个研究西方的商业机构如何将顾客满意作为商业活动的一个基本目标,并将其置于获取利润之上的管理学原理.本文主要阐述政府部门如何运用用户满意的概念来改进管理实践.公共管理领域中用户满意的概念定义为公共组织或机构如何履行自己的责任和义务.政府机构做得好坏取决于他们的国家管理类型,即是以下四种方式中的哪一种:"弱"型、"强"型、"过渡"型和"世袭"型,政府的管理采取上述方式中的哪一种既决定着其各个部门如何履行其职责,也决定着该政府如何利用用户满意策略来改进管理和机构.     

用四极型SIMS对砷化镓中硅定量分析的研究

ＧａＡｓ中Ｓｉ的定量分析是典型的ＳＩＭＳ分析课题，有明确的应用背景。文中对影响ＳＩＭＳ定量分析的一些基本因素进行了实验研究，用Ｏ２＋源和Ｃｓ＋源对均匀掺硅和离子注入硅的ＧａＡｓ样品进行了定量分析，考察了实验的稳定性。     

An amino-acid substitution involved in phenylketonuria is in linkage disequilibrium with DNA haplotype 2

Phenylketonuria (PKU) is an autosomal recessive human genetic disorder caused by a deficiency of hepatic phenylalanine hydroxylase (PAH, phenylalanine 4-monooxygenase, EC 1.14.16.1). PKU is a common inborn error of amino-acid metabolism in caucasian populations and approximately 1 in 50 individuals are carriers of a PKU allele. To define the molecular basis of PKU, we characterized twelve restriction fragment-length polymorphism (RFLP) haplotypes of the PAH locus in the northern European population and observed that 90% of the PKU alleles in this population are confined to four common RFLP haplotypes. We have recently reported a splicing mutation in the PAH gene that is associated with RFLP haplotype 3 which is present at about 40% of mutant alleles. We now report the molecular lesion associated with the RFLP haplotype 2 mutant allele. This defect is caused by a C-to-T transition in exon 12 resulting in an amino-acid substitution (Arg to Trp) at residue 408 of PAH. Direct hybridization analysis of the point mutation using a specific oligonucleotide probe demonstrated that this mutation is also in linkage disequilibrium with RFLP haplotype 2 alleles that make up about 20% of mutant PAH genes.     

Integration of Machining and Measuring Processes Using On-Machine Measurement Technology

This paper presents an integration methodology for ma chining and measuring processes using OMM (On-Machine Measurement) technology b ased on CAD/CAM/CAI integration concept. OMM uses a CNC machining center as a me asuring station by changing the tools into measuring probes such as touch-type, laser and vision. Although the measurement accuracy is not good compared to tha t of the CMM (Coordinate Measuring Machine), there are distinctive advantages us ing OMM in real situation. In this paper, two topics a...     

固相胰酶催化Leu~(B30)胰岛素的半合成

用猪、牛等动物胰岛素对糖尿病患者做冶疗时,因这些胰岛素对人体是异体蛋白,在不同程度上具有一定的免疫反应性,长期服药会产生副作用。因此,近年来酶促半合成人胰岛素的研究受到了人们的重视。据报道,Leu~(B30)胰岛素对人体具有最小的免疫反应性,且又有与人胰岛素相同的治疗作用。用固定化酶来进行Leu~(B30)胰岛素的半合成至今未见报道。我们以猪胰岛素为原料,用固相胰酶催化半合成了Leu~(B30)胰岛素,并以天然胰酶促半合成为对     

三维布局的一种优化算法

分析了布局问题的特性，综合利用“爬山”策略思想和实体的八叉树操作语言，提出一种适合于三维实体布局的优化算法。实例表明，该算法能从任一初始布局方案快速收敛到一个局部最优的布局。此外，对实体八叉树旋转的操作语言进行了研究并给出相应的算法。