中国八种家鼠C-带核型的比较研究

对我国大陆八种家鼠的C-带核型进行了比较研究, 并将C-带差异数量化 进 行模糊聚类分析 结果表明: 八种家鼠的C-带核型相互间存在一定的差异, 通过 分析, 得到了八种家鼠的聚 类分析分支图, 分为二大组: 斯氏家鼠和环齿鼠为 一组 其余种类为另一组。图版1图1表4参23

两种长臂猿染色体的C���和Ag-NORs的比较研究

白眉长臂猿和白颊长臂猿的染色体C���核型中除多数染色体有着丝点C���外,一些染色体上还出现插入C���和着丝点C���弱化或减少现象;白眉长臂猿有全异染色质臂;白颊长臂猿有较多的端位C���。白眉长臂猿有两个Ag-NORs,而白颊长臂猿的Ag-NORs雌体有4个,雄体有5个,Y染色体上有NOR。

p53蛋白质C���的三维结构及生物功能区

利用p53 C���118个氨基酸的mRNA二级结构和Chou-Fasman蛋白质二级结构预测原则,预测p53蛋白质C���289-325为卷曲肽段,368-393段包括两段螺旋结构:#alpha#_(1)368-373、#alpha#_(2)381-388。其中三段已知的蛋白质二级结构与此mRNA二级结构单元间有准确的对应关系。与四种以多重序列联配为基础的蛋白质二级结构预测方法(准确率均为73.20%左右)相对照,预测结果基本一致。结合单体聚合区31个氨基酸晶体结构,在SGI INDIGO~(2)工作站上构建了p53 C���108个残基的三维结构。进一步揭示了p53 C���诸多生物功能区之间的空间构象关系。

The three dimensional structure and biological domains of the p53 C-terminus.

It was expected that there are a coil (289 similar to 325) and two a helix (alpha(1)368 similar to 373, alpha(2)381 similar to 388) structures in p53 protein C-terminal region based on its mRNA secondary structure template and Chou-Fasman's protein secondary structure principle of prediction. The result was conformed by the other four methods of protein secondary structure prediction that are based on the multiple sequence alignment (accuracy = 73.20%). Combine with the 31 amino acids crystal structure of the oligomerization, the three dimensional conformation of p53 C-terminal 108 residues was built using the SGI INDIGO(2) computer. This structure further expounds the relationship among those biological function domains of p53 C- terminus at three-dimensional level.

Molecular modeling on some human interleukins sharing gamma c of interleukin-2 receptor, and structure-function relationships

Five models for human interleukin-7 (HIL-7), HIL-9, HIL-13, HIL-15 and HIL-17 have been generated by SYBYL software package. The primary models were optimized using molecular dynamics and molecular mechanics methods. The final models were optimized using a steepest descent algorithm and a subsequent conjugate gradient method. The complexes with these interleukins and the common gamma chain of interleukin-2 receptor (IL-2R) were constructed and subjected to energy minimization. We found residues, such as Gln127 and Tyr103, of the common gamma chain of IL-2R are very important. Other residues, e.g. Lys70, Asn128 and Glu162, are also significant. Four hydrophobic grooves and two hydrophilic sites converge at the active site triad of the gamma chain. The binding sites of these interleukins interaction with the common gamma chain exist in the first helical and/or the fourth helical domains. Therefore, we conclude that these interleukins binds to the common gamma chain of IL-2R by the first and the fourth helix domain. Especially at the binding sites of some residues (lysine, arginine, asparagine, glutamic acid and aspartic acid), with a discontinuous region of the common gamma chain of IL-2R, termed the interleukins binding sites (103-210). The study of these sites can be important for the development of new drugs. (C) 2000 Elsevier Science B.V. All rights reserved.

High prevalence of HIV-1 and hepatitis C virus coinfection among injection drug users in the southeastern region of Yunnan, China

The southeastern region of Yunnan province is a key site for drug trafficking and HIV-1 infection spread from the west of Yunnan and Laos to southeastern China. To investigate the prevalence of HIV-1 infection and hepatitis C virus (HCV) coinfection among injection drug users (IDUs) in southeastern Yunnan, three cohorts of 285 addicts, including 242 IDUs and 43 oral drug users, living in the cities of Gejiu and Kaiyuan and the county of Yanshan were studied. HIV-1 and HCV infections were detected by enzyme-linked immunosorbent assay and/or polymerase chain reaction. Data on the age, sex, risk behavior, drug use history, employment, ethnic background, and marriage status were obtained by interview. The overall prevalence of HIV-1 infection was 71.9%. The rate of HCV coinfection among 138 HIV-1-infected IDUs was 99.3%. Most HIV-infected IDUs were 20 to 35 years old (86.7%) and were ethnic Han (75.9%), suggesting that the epidemic in Yunnan is no longer confined to non-Han ethnic minorities, HIV prevalence in female IDUs (81.2%) was significantly higher than in male IDUs (68.2%) (p <.05). The prevalence of HIV infection reached 68.4% after 1 year of injection drug use. Needle/syringe sharing is the major high risk factor for the spread of HIV-1 and HCV infections. Large-scale educational campaigns are urgently needed to reduce the spread of HIV and HCV infection in these regions.

Deposition of c-axis orientation aluminum nitride films on flexible polymer substrates by reactive direct-current magnetron sputtering

Aluminum nitride (AlN) piezoelectric thin films with c-axis crystal orientation on polymer substrates can potentially be used for development of flexible electronics and lab-on-chip systems. In this study, we investigated the effects of deposition parameters on the crystal structure of AlN thin films on polymer substrates deposited by reactive direct-current magnetron sputtering. The results show that low sputtering pressure as well as optimized N 2/Ar flow ratio and sputtering power is beneficial for AlN (002) orientation and can produce a highly (002) oriented columnar structure on polymer substrates. High sputtering power and low N 2/Ar flow ratio increase the deposition rate. In addition, the thickness of Al underlayer also has a strong influence on the film crystallography. The optimal deposition parameters in our experiments are: deposition pressure 0.38 Pa, N 2/Ar flow ratio 2:3, sputtering power 414 W, and thickness of Al underlayer less than 100 nm. © 2012 Elsevier B.V. All rights reserved.

Room-temperature remote-plasma sputtering of c-axis oriented zinc oxide thin films

Highly c-axis oriented ZnO films have been deposited at room temperature with high rates (∼50 nm·min -1) using an innovative remote plasma sputtering configuration, which allows independent control of the plasma density and the sputtering ion energy. The ZnO films deposited possess excellent crystallographic orientation, high resistivity (>10 9 Ω·m), and exhibit very low surface roughness. The ability to increase the sputtering ion energy without causing unwanted Ar + bombardment onto the substrate has been shown to be crucial for the growth of films with excellent c-axis orientation without the need of substrate heating. In addition, the elimination of the Ar + bombardment has facilitated the growth of films with very low defect density and hence very low intrinsic stress (100 MPa for 3 μm-thick films). This is over an order of magnitude lower than films grown with a standard magnetron sputtering system. © 2012 American Institute of Physics.

饲料中不同维生素C���量对长吻的影响

用维生素C���量为38、364和630mg/kg的三种饲料饲喂初体重为(23.19±0.58)g的长吻8个月,实验结果表明,38mg/kgVC���料组饲喂的长吻表现出了典型的VC���乏症状:体色发黑,脊椎侧弯,鳍边由开始的萎缩直到腐烂、贫血、特定生长率显著降低(p<0.05)。并且38mg/kgVC���料组长吻的生理指标也受到影响:血清溶菌酶活性显著下降(p<0.05),肝脏的SOD活性及MDA含量均显著升高(p<0.05),血清皮质醇没有显著差异(p>0.05),但各处理组长吻肝脏中均未检测到诱导型HS

低C/N对湿地中硝化反硝化作用的影响

通过监测几种形态氮的变化,研究了人工湿地小试系统在不同浓度和低C/N条件下的除氮效果和反硝化途径.结果发现,湿地对浓度为5.5～50.5mg/L的NH4+-N有很好的去除效果,去除率可达95%以上.在此浓度范围内,NH4+-N的进、出水浓度呈线性关系,R2值为0.9971.当进水含氮量低于16.4mg/L时,湿地的除氮效率随进水浓度的增加而明显增加.进水含氮量为16.4～51.4mg/L时,湿地的除氮效率为85%以上,且浓度对去除率无显著影响.当C/N<1时,湿地系统对总氮的去除率为86.3%,而碳源充足

3D modeling of high-T c superconductors by finite element software

A three-dimensional (3D) numerical model is proposed to solve the electromagnetic problems involving transport current and background field of a high-T c superconducting (HTS) system. The model is characterized by the E-J power law and H-formulation, and is successfully implemented using finite element software. We first discuss the model in detail, including the mesh methods, boundary conditions and computing time. To validate the 3D model, we calculate the ac loss and trapped field solution for a bulk material and compare the results with the previously verified 2D solutions and an analytical solution. We then apply our model to test some typical problems such as superconducting bulk array and twisted conductors, which cannot be tackled by the 2D models. The new 3D model could be a powerful tool for researchers and engineers to investigate problems with a greater level of complicity.