Characterization of YBCO Bulk samples by local AC-susceptometry

Melt processed HTSC bulk samples usually show a high inhomogeneity. These inhomogeneities influence application-relevant properties such as the lévitation force or the trapped field. In this contribution a technique is presented which allows investigation of these inhomogeneous properties. The measurements are performed by scanning the sample surface with a small coil system and detecting the first and third harmonic of the inductive response. The critical current density jc is calculated from the measured signal using a modified critical state model. Jcdistributions yielded by this technique are shown. © 1997 IEEE.

槐花提取化合物K3体外抗HIV-1活性的研究

目的:研究槐花提取化合物K3的体外抗HIV-1活性,并对其抗HIV-1机制进行初步探讨.方法:采用MTT比色法检测化合物对各种细胞的毒性.用合胞体形成计数法,p24抗原捕获ELISA法及RT-PCR等多种方法研究化合物体外抗HIV-1活性.结论:槐花提取化合物K3体外有较好的抗HIV-1活性,能够抑制病毒实验株(HIV-1ⅢB,耐药株(HIV-1 74v)和临床分离株(HIV-1KM018)等多种病毒株的复制,且其作用机制是多靶点的,不仅可以抑制病毒的进入,还可以抑制HIV-1逆转录酶活性.

青鳉与三刺鱼嗅觉受体(OR)基因的鉴定与进化分析

嗅觉是动物至关重要的感官,而嗅觉受体基因则构成了嗅觉的基础.嗅觉受体跟环境气味分子的相互作用被认为是嗅觉过程发生的第一步.气味分子结合被认为发生在由跨膜区形成的一个口袋结构中,而直接结合位点叫做绑定位点.以往的研究显示,绑定位点可能因为功能分化而受到正向选择.本研究对青鳉和三刺鱼的基因组中鉴定了OR基因,并对这些序列进行了进化分析.通过不同跨膜区与整个编码区的选择压力的比较,发现跨膜区4,5,6有较高的平均Ka/Ks值,这可能在某种程度上由正向选择所致.同时发现,许多受正向选择的位点主要分布在跨膜区.通过

中国水污染综合治理的生态学思考

<正>中国水污染现状当前的中国,水污染和水体富营养化已成为严重的环境问题。经济合作组织(OECD)2007年7月17日的报告称,中国主要城市水质近一半不完全符合饮用水源水质标准。污染源当中,最主要的是粪便排污,其次为工业和农业化学污染;

线虫系统发育研究进展

线虫是多样性仅次于昆虫的一个动物类群．秀丽隐杆线虫已经成为现代发育生物学、遗传学和基因组学研究的重要模式材料．然而线虫的系统位置及其系统发育关系一直争议颇多．近年来，分子系统发育研究使经典线虫系统学面临巨大的挑战，不仅提出了线虫属于蜕皮动物以及线虫五大分支系统等新观点，同时为动物分子鉴定和系统发育多样性研究提供了新思路．

Characterization of the Rana grylio virus 3 beta-hydroxysteroid dehydrogenase and its novel role in suppressing virus-induced cytopathic effect

The 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) isoenzymes play a key role in cellular steroid hormone synthesis. Here, a 3 beta-HSD gene homolog,was cloned from Rana grylio virus (RGV), a member of family Iridoviridae. RGV 3 beta-HSD gene has 1068 bp, encoding a 355 aa predicted protein. Transcription analyses showed that RGV 3 beta-HSD gene was transcribed immediate-early during infection from an initiation site 19 nucleotides upstream of the translation start site. Confocal microscopy revealed that the 3 beta-HSD-EGFP fusion protein was exclusively colocalized with the mitochondria marker (pDsRed2-Mito) in EPC cells. Upon morphological observation and MTT assay, it was revealed that overexpression of RGV 3 beta-HSD in EPC cells could apparently suppress RGV-induced cytopathic effect (CPE). The present studies indicate that the RGV immediate-early 3 beta-HSD gene encodes a mitochondria-localized protein, which has a novel role in suppressing virus-induced CPE. All these suggest that RGV 3 beta-HSD might be a protein involved in host-virus interaction. @ 2006 Elsevier Inc. All rights reserved.

Investigation of mode characteristics for microdisk resonators by S-matrix and three-dimensional finite-difference time-domain technique

The mode characteristics of a three-dimensional (3D) microdisk with a vertical refractive index distribution of n(2)/3.4/n(2) are investigated by the S-matrix method and 3D finite-difference time-domain (FDTD) technique. For the microdisk with a thickness of 0.2 mu m. and a radius of 1 mu m, the mode wavelengths and quality factors for the HE7,1 mode obtained by 3D FDTD simulation and the S-matrix method are in good agreement as n(2) increases from 1.0 to 2.6. But the Q factor obtained by the 3D FDTD rapidly decreases from 1.12 X 10(4) to 379 as n2 increases from 2.65 to 2.8 owing to the vertical radiation losses, which cannot be predicted by the proposed S-matrix method. The comparisons also show that quality factors obtained from the analytical solution of two-dimensional microdisks under the effective index approximation are five to seven times smaller than those of the 3D FDTD as n(2) = 1 and R = 1 mu m. (c) 2006 Optical Society of America.

Modification of emission wavelength of self-assembled In(Ga)As/GaAs quantum dots covered by InxGa1-xAs(0 <= x <= 0.3) layer

Red shifts of emission wavelength of self-organized In(Cla)As/GaAs quantum dots (QDs) covered by 3 nm thick InxGa1-xAs layer with three different In mole fractions (x = 0.1, 0.2 and 0.3, respectively) have been observed. Transmission electron microscopy images demonstrate that the stress along growth direction in the InAs dots was reduced due to introducing the InxGa1-xAs (x = 0.1, 0.2 and 0.3) covering layer instead of GaAs layer. Atomic force microscopy pictures show a smoother surface of InAs islands covered by an In0.2Ga0.8As layer. It is explained by the calculations that the redshifts of the photoluminescence (PL) spectra from the QDs covered by the InxGa1-xAs (x greater than or equal to 0.1) layers were mainly due to the reducing of the strain other than the InAs/GaAs intermixing in the InAs QDs. The temperature dependent PL spectra further confirm that the InGaAs covering layer can effectively suppress the temperature sensitivity of PL emissions. 1.3 mum emission wavelength with a very narrow linewidth of 19.2 mcV at room temperature has been obtained successfully from In,In0.5Ga0.5As/GaAs self-assembled QDs covered by a 3-nm In0.2Ga0.2As strain reducing layer. (C) 2001 Elsevier Science B.V. All rights reserved.