Research on laser welding of vehicle body

Based on many experiments of CO₂ laser welding of vehicle body, joint microstructure and stress–strain curve of specimen are analyzed. The deep punching performance acquired by adopting Ar as protective gas is better than that of the one acquired by adopting N₂ as protective gas. Meanwhile the percentage of zinc in welding seam can be effectively controlled by means of blowing side protective gas. In this paper, welding penetration and width are shown to vary with laser power and speed of welding. The results indicate that some flaws such as gas hole, crack and softening of HAZ do not appear in laser welding seam in sheet steel of automobile bodies if technology parameters optimizes. The deep punching performance of tailor-welding sheet is fine.     

Investigation of DNA-protein sequence-specific interactions with a ds-DNA array

The sequence specific recognitions between DNAs and proteins play important roles in many biological functions. The use of double-stranded DNA arrays (ds-DNA arrays) for studying sequence specific recognition between DNAs and proteins is a promising method. Here we report the use of a ds-DNA probe with multi operation sites of restriction proteins in the middle sequence to investigate DNA-protein sequence-specific interactions including methylation. We arranged EcoR I site and Rsa I site on the same duplex DNA probe to fabricate ds-DNA arrays. We used the ds-DNA arrays to study DNA-restriction enzyme reactions before and after duplex DNA methylation under different probe concentration and reaction time conditions. Our results indicated that the ds-DNA arrays can be further biochemically modified and made accessible for interactions between DNAs and proteins in complex multi-step gene-regulation processes.     

On coleman outer automorphism groups of finite groups

Let G be a finite group and Out _Col(G) the Coleman outer automorphism group of G(for the definition, see below). The question whether Out_Col(G) is a p′-group naturally arises from the study of the normalizer problem for integral group rings, where p is a prime. In this article, some sufficient conditions for Out_Col(G) to be a p′-group are obtained. Our results generalize some well-known theorems.     

二极大子群为TI-子群的有限群的类保持Coleman自同构

设$H$是有限群$G$的一个子群,若对任意$g\in G$, $H\cap H^g=1$或者$H$,则称$H$为TI-子群. 设$G$是一个所有二极大子群为TI-子群的有限群,本文证明了$G$的每个类保持Coleman自同构是内自同构. 作为本结果的一个直接推论,得到了这样的群$G$有正规化子性质.     

On p-hypercenter of Finite Groups

In this paper, we investigate p-hypercenter of the finite group, and obtain some propertiesof p-hypercenter. As its application, we draw some conclusions on the p-nilpotent groups, ourconclusions generalize some well-known results.Throughout this paper, G is a finite group, p is a prime number. Set Zp(G) ={g ∈ G |'[g, G] 5 O.' (G)} and call it the p-center of G. Z;(G)(the p-hypercenter of G) is the largestterm of the chain of subgroupsWe give the characterizations of Z7(G) as follows:Pr…     

基于信息量度量的企业管理复杂性评价方法——神东煤炭公司管理复杂性评价

应用物理学、数学、力学、信息论、统计学和管理学等理论方法 ,提出了管理力、管理功和管理复杂度的基本概念、定义、基本原理和研究范围 ;并基于管理熵理论的基本原理 ,建立了企业管理系统复杂性评价的新尺度和评价方法 ;构造了尺度的矢量空间、数学模型及量化模型 ;对神东煤炭集团公司的企业组织管理系统复杂性进行了实例分析与评价 .     

Systematic evaluation of biocompatibility of magnetic Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles with six different mammalian cell lines

This article systematically evaluated the biocompatibility of multiple mammalian cell lines to 11-nm DMSA-coated Fe₃O₄ magnetic nanoparticles (MNPs). Cells including RAW264.7, THP-1, Hepa1-6, HepG2, HL-7702, and HeLa were incubated with six different concentrations (0, 20, 30, 40, 50, and 100 μg/mL) of MNPs for 48 h, and then the cell labeling, iron loading, cell viability, apoptosis, cycle, and oxidative stress were all quantitatively evaluated. The results revealed that all the cells were effectively labeled by the nanoparticles; however, the iron loading of RAW264.7 was significantly higher than that of other cells at any dose. The proliferations of all the cells were not significantly suppressed by MNPs at the studied dose except HepG2 that was exposed to 100 μg/mL MNPs. The investigation of oxidative stress demonstrated that the levels of total superoxide dismutase and xanthine oxidase had no significant changes in all the cells treated by all the doses of MNPs, while the levels of malonyldialdehyde activity of MNP-treated cells significantly increased. The nanoparticles did not produce any significant effect on cell cycles at any of the doses, but resulted in significant apoptosis of THP-1 and HepG2 cells at the highest concentration of 100 μg/mL. At a concentration of 30 μg/mL which was used in human studies with an intravascular nanoparticle imaging agent (Combidex), the nanoparticles efficiently labeled all the cells studied, but did not produce any significant influence on their viability, oxidative stress, and apoptosis and cycle. Therefore, the nanoparticles were concluded with better biocompatibility, which provided some useful information for its clinical applications.     

具有唯一非平凡正规子群的有限群的Coleman自同构

Let G be a finite group with a unique nontrivial normal subgroup. It is shown that every Coleman automorphism of G is an inner automorphism.