一株金黄色葡萄球菌噬菌体SAK84P的分离鉴定

金黄色葡萄球菌(Staphylococcus aureus,S.aureus)是一类革兰氏阳性致病菌,临床分离株通常对于多种抗生素具有耐药性.从该菌中分离出高效、广谱的专一性噬菌体,对于治疗临床耐药金黄色葡萄球菌的感染具有重要意义.该文以S.aureus K84为宿主菌,从污水中分离出一株烈性噬菌体SAK84P.通过透...     

复杂性测度在肌电信号模式识别中的应用

针对表面肌电信号(SEMG)的非平稳特性,提出了一种以复杂性测度和支持向量机(SVM)相结合的肌电信号模式识别新方法。肌电信号的复杂度作为一种新的肌电信号特征,算法简单。支持向量机是一种新的机器学习机制。通过对采集的四通道表面肌电信号进行分析,提取其复杂性测度信息构建特征矢量,利用“一对一”分类策略和二叉树构建的多类支持向量机分类器,很好地实现了对前臂的八种动作表面肌电信号的模式分类。实验表明,由支持向量机对肌电信号的复杂度特征进行分类,具有很好的稳定性和准确率,为肌电信号及其它非平稳生理电信号的模式分类提供了一种新思路。     

御“马”于千里之外 安天“木马防线”初试

安天实验室(www.antiy．com)最新推出的反木马鞍件——“木马防线”能查杀3万多种恶意木马，蠕虫等病毒，其木马防火墙与在线监控功能可以把木马盗杀在激活之前，此外还提供了多种易用的系统工具，供手工检查木马之用。     

生物免疫传感器检测迟缓爱德华氏菌研究

迟缓爱德华氏菌(E.tarda)是最为严重的水产动物致病菌之一,准确、即时的检测手段是预防控制该菌传播的关键所在.通过量子点(QDs)标记E.tarda单克隆抗体(Ab),利用生物免疫传感器技术实现E.tarda的快速、特异性检测.结果显示,QDs-Ab的荧光通过加入氧化石墨烯(GO)产生淬灭,构建了捕获目标细菌的探针,GO最适淬灭浓度为60μg/L.细菌捕获探针中加入E.tarda后,能够检测到重新恢复强度的橙色荧光.针对E.tarda设计的生物免疫传感器的特异性,选取灿烂弧菌、溶藻胶弧菌、副溶血弧菌和嗜水气单胞菌作为对照,结果显示,对照组不能明显引起荧光强度的改变,而实验组却能显著提高荧光强度.本研究建立的基于荧光能量共振转移(FRET)的具有高灵敏度和特异性的生物传感器检测方法在细菌的早期诊断中有良好的应用潜质.     

主攻防御分三级KV2010带你逐步深化

杀毒能力并不是权衡一个杀软的关键因素，其最重要的应是防御。一旦感染了病毒，很多数据就将遭到严重的破坏，此时再杀毒已经为时晚矣。因此，要想彻底杜绝病毒应该早早地把病毒置之门外。但是，首先你要学会开启自己所用的杀毒软件的主动防御功能，下面以江民公司的KV2010为例来说明。     

基于肌音信号图像化和卷积神经网络的手语识别研究

时间序列信号被广泛应用于各种模式识别的场合,针对大量目标的时间序列信号模式识别率低的问题,借助多种图像化手段,将时间序列信号转换为图像,采用图像分类算法实现模式识别.实验中采集了前臂上30种手语对应的肌音信号(Mechanomyography,MMG),将其转换为不同风格的图像,设计卷积神经网络(Convolution Neural Network,CNN)框架,对图像化的肌音信号训练集建立模式识别的分类模型,并且应用迁移学习(transfer learning)算法对模型进行多次优化,建立的分类模型识别率达98.7％,高于普通机器学习算法的识别率.实验结果证明了图像化处理时间序列信号可以有效提高多分类肌音信号模式识别的识别率,该研究可以为其他时间序列信号的模式识别研究提供参考.     

KV300的硬盘维护功能及技巧

超级巡警KV300是目前较流行的一种反病毒软件，由于其直杀病能力强大、使用方便、查杀病毒速度迅速等诸多优点，倍受广大电脑用户的喜爱。另一方面KV300还具有快速检测、修复与维护硬盘的特殊功能，同时可以直接观察硬盘的隐含扇区，尤其是当硬盘出现故障不能自行引导而瘫痪时，用户即便未备份硬盘主引导信息，KV300能照样运行，检测硬盘故障所在，并可查杀已瘫痪硬盘上的病毒，这是许多软件所不具备的，更显其独特本领。通常正常硬盘应具备有引导的最关键信息：①主引导记录信息，位于硬盘的起始部分即0面0道1扇区，长度为512字节；②D…     

地衣芽孢杆菌α-耐高温淀粉酶基因的克隆及在大肠杆菌中的表达

地衣芽孢杆菌(Bacilluslicheniformis)是产生具有重要工业生产价值的耐高温α -淀粉酶(α -amylase)的优良菌株。在提取地衣芽孢杆菌基因组DNA基础上 ,通过PCR方法克隆了耐高温淀粉酶的全长基因1539bp ,与pUCm -T载体连接转化入克隆菌DH5α中 ,经过酶切鉴定筛选出阳性的克隆菌 ,再提取质粒与表达载体pET-28a( )酶切后连接转化入宿主菌DE3中 ,其阳性重组子在37℃1.0mmol·L-1IPTG诱导下 ,α -淀粉酶的基因得到了较好的表达。表达产物经SDS -PAGE鉴定 ,确定表达蛋白的相对分子量为63000左右 ,与理论推导的分子量相一致。     

刺科线虫中国新记录种-纤细居中线虫(Geocenamus tenuidens)的描述

详细描述了植物寄生线虫新记录属居中属(Geocenamus)的一新记录种——纤细居中线虫(Geocenamus tenuidens)。居中属线虫是我国首次发现的刺科线虫的一新记录属。纤细居中线虫的鉴别特征为虫体环纹明显；头区显著缢缩，鳞球状，头环5个；口孔突出；口针纤细，锥部长于杆部；侧线6条；雌虫阴门凹陷，阴道壁加厚，具有阴门唇；双卵巢，对伸；尾较短，亚圆筒形，末端具环纹；雄虫尾轻微弯曲，宽阔的交合伞包至尾端；交合刺不伸出泄殖腔。该种线虫与其近缘种北方居中线虫(Geocenamus arctic)的区别：纤细居中线虫口针相对较短，尾末端具环纹；北方居中线虫口针较长，尾末端光滑。     

用植物病毒载体表达小球状病毒抗原蛋白的研究

将引起人类腹泻主要病原物小球状病毒(Small round structured virus;SRSV)编码抗原蛋白基因的全长序列1605bp,导入来自三叶草黄脉病毒(Clover yellow vein virus;ClYVV)侵染性全长cDNA克隆的侵染性植物病毒表达载体pClYVV/CP/W基因组的NIb/CP基因之间,构建了重组病毒克隆pClYVV-NV1.6。用上述重组病毒克隆接种蚕豆植物,表现了与野生型ClYVV相同的症状。从发病叶中提取总RNA,用反转录PCR(RT-PCR)对上述重组病毒克隆的转录进行了检测,结果表明,外源基因在F4子代病毒基因组中仍然稳定存在。从发病叶中提取总蛋白,用酶联免疫吸附分析(Enzyme-linked immunosorbent assay;ELISA)及蛋白质杂交(Western blotting;WB)对上述重组病毒克隆表达的目的基因产物抗原蛋白进行了测定,结果表明,重组病毒克隆pClYVV-NV1.6之目的基因产物的表达量随寄主植物发病后时间的推移而变化,最大表达是在寄主植物发病后第9天,最大表达量为每克鲜叶可表达160.00μg,这一研究结果为用植物生产抗SRSV口服疫苗提供了有力的基础。     

ZnFe2O4 tubes: Synthesis and application to gas sensors with high sensitivity and low-energy consumption

ZnFe₂O₄ tubes with mesoscale dimensions were synthesized by pyrolysis of polyvinyl alcohol (PVA)-mediated xerogel using porous alumina as a template. The product formation was analyzed by X-ray powder diffraction (XRD), Fourier transformation infrared spectroscopy (FT-IR), thermogravimetry and differential thermal analysis (TG–DTA), scanning electronic microscopy (SEM), transmission electron microscopy (TEM) and high-resolution TEM (HRTEM). This synthetic method yielded open-ended ZnFe₂O₄ tubes with a typical length of several micrometers, an outer diameter of about 200 nm, and an average thin wall of 20 nm composed of small nanocrystals. Application of the ZnFe₂O₄ tubes as gas sensor materials displayed low-energy consumption and high sensitivity to organics such as ethanol and acetone, due to the unique interconnected channel structure and small crystal size of the tubes, showing their potential application in sensor areas.     

Acetylene sensor based on Pt/ZnO thick films as prepared by flame spray pyrolysis

ZnO nanoparticles loaded with 0.2-2.0 at.% Pt have been successfully produced in a single step by flame spray pyrolysis (FSP) technique using zinc naphthenate and platinum(II) acetylacetonate, as precursors dissolved in xylene and their acetylene sensing characteristics have been investigated. The particle properties were analyzed by XRD, BET, TEM, SEM and EDS. Under the 5/5 (precursor/oxygen) flame condition, ZnO nanoparticles and nanorods were observed. The crystallite sizes of ZnO spherical and hexagonal particles were found to be ranging from 5 to 20 nm while ZnO nanorods were seen to be 5-20 nm in width and 20-40 nm in length. In addition, very fine Pt nanoparticles with diameter of ∼1 nm were uniformly deposited on the surface of ZnO particles. From gas-sensing characterization, acetylene sensing characteristics of ZnO nanoparticles is significantly improved as Pt content increased from 0 to 2  at.%. The 2 at.% Pt loaded ZnO sensing film showed an optimum C₂H₂ response of ∼836 at 1% acetylene concentration and 300 °C operating temperature. A low detection limit of 50 ppm was obtained at 300 °C operating temperature. In addition, Pt loaded ZnO sensing films exhibited good selectivity towards hydrogen, methane and carbon monoxide.     

Designing a parallel cloud based comparative genomics workflow to improve phylogenetic analyses

Over the last years, comparative genomics analyses have become more compute-intensive due to the explosive number of available genome sequences. Comparative genomics analysis is an important a prioristep for experiments in various bioinformatics domains. This analysis can be used to enhance the performance and quality of experiments in areas such as evolution and phylogeny. A common phylogenetic analysis makes extensive use of Multiple Sequence Alignment (MSA) in the construction of phylogenetic trees, which are used to infer evolutionary relationships between homologous genes. Each phylogenetic analysis aims at exploring several different MSA methods to verify which execution produces trees with the best quality. This phylogenetic exploration may run during weeks, even when executed in High Performance Computing (HPC) environments. Although there are many approaches that model and parallelize phylogenetic analysis as scientific workflows, exploring all MSA methods becomes a complex and expensive task to be performed. If scientists determine a priorithe most adequate MSA method to use in the phylogenetic analysis, it would save time, and, in some cases, financial resources. Comparative genomics analyses play an important role in optimizing phylogenetic analysis workflows. In this paper, we extend the SciHmm scientific workflow, aimed at determining the most suitable MSA method, to use it in a phylogenetic analysis. SciHmm uses SciCumulus, a cloud workflow execution engine, for parallel execution. Experimental results show that using SciHmm considerably reduces the total execution time of the phylogenetic analysis (up to 80%). Experiments also show that trees built with the MSA program elected by using SciHmm presented more quality than the remaining, as expected. In addition, the parallel execution of SciHmm shows that this kind of bioinformatics workflow has an excellent cost/benefit when executed in cloud environments.     

A refined circular template matching method for classification of human cytomegalovirus capsids in TEM images

An automatic image analysis method for describing, segmenting, and classifying human cytomegalovirus capsids in transmission electron micrograph (TEM) images of host cell nuclei has been developed. Three stages of the capsid assembly process in the host cell nucleus have been investigated. Each class is described by a radial density profile, which is the average grey-level at each radial distance from the center. A template, constructed from the profile, is used to find possible capsid locations by correlation based matching. The matching results are further refined by size and distortion analysis of each possible capsid, resulting in a final segmentation and classification.     

纳米SnO2材料的晶化及其对气敏特性的影响’

本文对以无水SnCl_4为源、采用低温等离子体法制备的10nm量级的SnO_2粉料的晶化现象进行了多方面的讨论.由DTA得到了这种粉料的晶化温度;结合IR分析了升温过程中粉料的失重原因;从X-射线衍射谱图中分析了制得粉料的热稳定性.在晶化温度前后对粉料进行热处理,得到了不同的电导-温度曲线.比较了两种温度烧结制得的气敏元件的灵敏度.     

二氧化锡纳米粉料的制备及其气敏性能

采用低温等离子体法以无水四氯化锡为源物质制备了二氧化锡超微粉料,TEM照片显示粉料粒度均匀,粒径为10nm量级,并且阴极高压越高,粒径越小。用该粉料制备的气敏元件,测定了气体灵敏度与温度及浓度的关系,显示了比一般无渗杂氧化锡元件灵敏度高的特点,可望开发成为广普型气敏传感器。还讨论了元件的灵敏度和电导温度特性随不同热处理温度的变化。大的比表面积在这种类型传感器运行机制中起着重要作用.     

系统发育与古细菌Val-tRNA合成酶耐热性的关系

嗜热古细菌和常温古细菌的氨基酰-tRNA合成酶在生物合成蛋白质中都起着至关重要的作用,它们的功能相似而耐热性相差很大。为了阐明氨基酰-tRNA合成酶的耐热机制,本文从进化角度研究了具有全基因组的8种超高温古细菌、3种高温古细菌和2种常温古细菌的Val-tRNA合成酶耐热性的差异。从构建的进化树可知,不同的微生物依据其耐热性而严格的分开;进化关系较近的4种微生物,都是产甲烷的古细菌;序列比对结果表明,耐热Val-tRNA合成酶中的带电荷氨基酸随着进化,突变为疏水性氨基酸,表明常温Val-tRNA合成酶中缺乏像耐热Val-tRNA合成酶中形成盐桥的氨基酸。这表明盐桥是氨基酰-tRNA合成酶耐热的主要因素。     

基于粗粒化的流感病毒蛋白进化树构建*

在127065条血凝素、神经氨酸酶流感病毒蛋白基础上,提出基于粗粒化的病毒蛋白进化树的构建方法.首先基于病毒蛋白序列特征,给出序列间相似性度量,提取流感病毒系统层次递阶结构,并定义层次聚类指标,确定最佳聚类数.然后基于距离中心最近的原则提取流感病毒系统代表.最后采用距离度量构造流感病毒进化树.实验表明,相同流感病毒具有宿主相同、时间跨度较小、爆发地点相近,更倾向于处于相同分支的特点,这与已有的文献吻合,因此该方法有利于挖掘病毒变异轨迹.     

Some Algorithmic Challenges in Genome-Wide Ortholog Assignment

Genome-scale assignment of orthologous genes is a fundamental and challenging problem in computational biology and has a wide range of applications in comparative genomics, functional genomics, and systems biology. Many methods based on sequence similarity, phylogenetic analysis, chromosomal syntenic information, and genome rearrangement have been proposed in recent years for ortholog assignment. Although these methods produce results that largely agree with each other, their results may still contain signi...     

广义统计区域合并的SAR图像浮筏养殖信息提取

目的 海水浮筏养殖是海域使用动态监测中的重要类型,合成孔径雷达（SAR）卫星遥感影像可以克服海洋气象环境的影响,有效反映浮筏养殖区域。由于浮筏养殖信息受乘性相干斑噪声污染严重,为了降低噪声敏感性,改进得到广义局部二值模式（GLBP）,进而将其用于改进广义统计区域合并算法（GSRM）,构建以GLBP_GSRM为核心的多特征集成模型,得到更具纹理一致性的超像素,实现浮筏养殖信息精确提取。方法 根据SAR数据的乘性噪声特性改进局部二值模式算子得到GLBP算子,将其加入GSRM的合并准则中,结合纹理信息的超像素分割能得到更具纹理一致性的超像素,有效抑制相干斑噪声。进而利用非下采样轮廓波变换得到轮廓信息丰富数据特征,使用FCS（fuzzy compactness and separation）算法聚类实现浮筏养殖信息的无监督提取。结果 实验选取辽宁省长海县邻近海域作为研究区域,针对C波段的Radarsat-2 SAR和X波段的TerraSAR图像,分别比较同一图像不同区域和不同图像同一区域的提取结果,结合实地现场调查结果表明所提模型对不同类型SAR图像均能精确无监督地提取浮筏养殖信息,分类精度均高于85%,明显优于经典无监督算法,验证模型的有效性。结论 所提模型充分集成纹理特征、空间特征和轮廓特征,有效解决相干斑噪声干扰信息提取的问题,针对不同类型SAR遥感图像,均能在复杂的海洋背景中实现有效地无监督浮筏养殖信息提取,提高海水养殖自动监测准确度。