聚乳酸非织造材料可生物降解环境中菌群结构分析及调控

为建立非织造材料可生物降解性能的快速检测方法,选择土壤这一自然降解环境介质进行生物降解试验。通过对富集土壤中的混合菌群液配制成生物快速降解环境,运用平板计数和PCR-DGGE技术对该环境中降解前后的细菌菌群结构变化进行分析。结果表明,所富集的土壤细菌混合菌群不仅在传代转接过程,还是在整个生物降解试验周期中,优势菌的数量和种类始终保持相对稳定,确保生物降解的持续性。同时根据对非织造材料生物降解过程中的无机碳含量检测分析,验证了在整个降解周期中细菌菌群发生生物降解的有效性;并通过调节不同浓度的降解试验菌液,可以调控生物降解的速度,从而实现不同的生物降解效果。     

PLA非织造材料可生物降解环境中菌群结构分析及调控

为建立非织造材料可生物降解性能的快速检测方法,选择土壤这一自然降解环境介质进行生物降解试验,通过对富集土壤中的混合菌群液配制成生物快速降解环境,运用平板计数和PCR-DGGE技术对该环境中降解前后的细菌菌群结构变化进行分析。结果表明,所富集的土壤细菌混合菌群不仅在传代转接过程,还是在整个生物降解试验周期中,优势菌的数量和种类始终保持相对稳定,确保生物降解的持续性。同时根据对非织造材料生物降解过程中的无机碳含量检测分析,验证了在整个降解周期中细菌菌群发生生物降解的有效性,并通过调节不同浓度的降解试验菌液,可以调控生物降解的速度,从而实现不同的生物降解效果。     

小麦苗期根系mRNA的稳定性分析

转录后调控是基因表达调控的重要方式,其中mRNA稳定性是转录后调控的有效途径之一．实验采用cDNA—AFLP技术,对小麦杂交种3338／2463与其亲本苗期根系中的mRNA稳定性进行了分析．结果显示,在所检测到的2995条带中,有96条的丰度经3’脱氧腺苷处理60min后在至少一个材料中表现为明显降低,占总数的3．21％,表明这些条带所代表的mRNA半衰期比较短,可能是不稳定mRNA．同源比对分析结果显示,在所鉴定出的74个编码不稳定mRNA的基因中,有30个与已知功能基因具有较高的同源性,其中既有转录因子和信号转导基因,还有一些结构基因,而其余44个为功能未知基因．比较分析发现,杂交种与亲本之间不稳定mRNA的比例没有显著差异,但是不同基因型之间不稳定mRNA的降解速度不同,其中WRKY和线粒体半ABC转运蛋白基因在杂交种中的下调表达可能与其mRNA在杂交种与亲本中的稳定性差异有关．     

小麦苗期根系mRNA的稳定性分析

转录后调控是基因表达调控的重要方式,其中mRNA稳定性是转录后调控的有效途径之一.实验采用cDNA-AFLP技术,对小麦杂交种3338/2463与其亲本苗期根系中的mRNA稳定性进行了分析.结果显示,在所检测到的2995条带中,有96条的丰度经3′脱氧腺苷处理60 min后在至少一个材料中表现为明显降低,占总数的3.21%,表明这些条带所代表的mRNA半衰期比较短,可能是不稳定mRNA.同源比对分析结果显示,在所鉴定出的74个编码不稳定mRNA的基因中,有30个与已知功能基因具有较高的同源性,其中既有转录因子和信号转导基因,还有一些结构基因,而其余44个为功能未知基因.比较分析发现,杂交种与亲本之间不稳定mRNA的比例没有显著差异,但是不同基因型之间不稳定mRNA的降解速度不同,其中WRKY和线粒体半ABC转运蛋白基因在杂交种中的下调表达可能与其mRNA在杂交种与亲本中的稳定性差异有关.     

医用藻酸盐敷料体外降解的研究

研究藻酸盐医用敷料体外降解的规律及不同降解时间其产物对内皮细胞增殖情况的影响,为藻酸盐医用敷料在临床使用中提供参考。以PBS缓冲液(模拟体液环境)为降解介质,对藻酸盐敷料进行体外降解;用藻酸盐敷料的失重率、分子质量变化表征本体的变化规律;用降解液中降解产物的糖醛酸含量变化表征降解产物的变化规律。将降解液与内皮细胞共培养,用MTT法检测内皮细胞增殖情况。藻酸盐敷料在模拟体液环境条件下,可以被降解,42 d失重率为61.2%,降解过程中其分子质量逐渐减小,最终产物为糖醛酸,其浓度不断增大。不同时间的降解产物均能促进内皮细胞的增殖。藻酸盐医用敷料体外降解比较快,完全降解的最终产物为糖醛酸,其降解液可以促进内皮细胞的增殖、分化,提高细胞新陈代谢能力,增加新细胞的再生速度,促进伤口的愈合。     

高聚合度PVC在硫酸中的老化

用红外光谱法研究了高聚合度PVC在硫酸中的老化现象。通过不同介质条件下硫酸对不同聚集合度PVC的作用。在对化硫酸作用前后和不同作用程度下的PVC光谱图中,发现硫酸先后与PVC中的稳定剂和不稳定基因作用,发生从降解到焦化的变化,是复杂的物理和化学过程。对高聚合度PVC在实际应用中的耐溶剂性和防老化工作,有较大参考价值。     

一步合成的聚乙醇酸在不同介质中的熔融水解

用一步合成法制备聚乙醇酸,并系统研究了熔融状态下在蒸馏水和氢氧化钠水溶液两种介质中的降解规律.降解过程中,在两种介质中,聚乙醇酸质量损失率均呈现出逐渐增大的趋势、熔点和特性黏数及介质pH值均逐渐降低,结晶度起初增大随后下降.在蒸馏水中降解,聚乙醇酸的结构无变化;在氢氧化钠水溶液中降解,结构变化较大.聚乙醇酸在氢氧化钠水溶液中熔融降解比在蒸馏水中显著.     

重组慢病毒介导的NMD途径因子UPF1和SMG1可诱导干扰细胞株的构建

无义介导的mRNA降解途径是一个比较完善的异常mRNA的降解机制,结合在外显子拼接复合体上的多种蛋白决定NMD途径对异常转录物的识别和降解的启动,其中UPF1和SMG1发挥主要功能.UPF1是一个RNA解旋酶和RNA依赖的ATP酶;而SMG1具有磷脂酰肌醇激酶活性,负责UPF1的磷酸化.本研究构建了含有UPF1和SMG-1基因发夹结构的诱导开关基因表达干扰质粒.利用慢病毒介导转化哺乳动物细胞HEK293T细胞得到重组病毒,经鉴定后感染细胞AD_293,目的基因在细胞中得以高效表达.通过继代培养和单克隆化,得到强力霉素诱导干扰UPF1和SMG-1表达的稳定细胞株.     

固定化微生物细胞降解苯酚的研究进展

从固定化细胞的微生物选择、细胞固定化载体的选择以及不同因素对固定化细胞降解苯酚效果的影响等方面介绍了固定化细胞技术在降解苯酚中的研究进展,指出了固定化细胞技术在降解苯酚应用中所存在的一些问题,并展望了固定化细胞技术应用于苯酚降解的前景。     

耐旱苔藓植物生理学及分子生物学研究进展

耐旱的藓类能快速脱水并存活,这种能力可由快速建立起来的对环境变化的耐受机制来反映.再水化时光合系统的原初恢复非常迅速,不依赖蛋白质的合成;ABA处理可显著改变PSII的生理特征;建成型的保护机制和再水化诱导的恢复机制才使苔藓植物显得独特.大量研究证明再水化期间Tortularuralis基因表达的改变,主要在转录后水平上调控,从性质上稳定的mRNA库选择和/或编码不同rehydrinmRNAs的结果.Tortularuralis有选择地吸收re-hydrinmRNAs,在脱水组织中贮存为mRNPs,为再水化做准备,这不仅保护了mRNAs,而且一旦获得水后,增加了反应速度.山墙藓Tortularuralis将会是研究耐干旱的重要模式植物.     

Asymmetric inheritance of centrosomally localized mRNAs during embryonic cleavages

During development, different cell fates are generated by cell-cell interactions or by the asymmetric distribution of patterning molecules. Asymmetric inheritance is known to occur either through directed transport along actin microfilaments into one daughter cell or through capture of determinants by a region of the cortex inherited by one daughter. Here we report a third mechanism of asymmetric inheritance in a mollusc embryo. Different messenger RNAs associate with centrosomes in different cells and are subsequently distributed asymmetrically during division. The segregated mRNAs are diffusely distributed in the cytoplasm and then localize, in a microtubule-dependent manner, to the pericentriolar matrix. During division, they dissociate from the core mitotic centrosome and move by means of actin filaments to the presumptive animal daughter cell cortex. In experimental cells with two interphase centrosomes, mRNAs accumulate on the correct centrosome, indicating that differences between centrosomes control mRNA targeting. Blocking the accumulation of mRNAs on the centrosome shows that this event is required for subsequent cortical localization. These events produce a complex pattern of mRNA localization, in which different messages distinguish groups of cells with the same birth order rank and similar developmental potentials.     

CORBA与Web Services的交互方法

企业信息化建设过程中构建了大量的CORBA应用.目前的B2B服务集成是在Internet上平台独立、松散耦合的集成.CORBA的特性决定了它不能满足这种需求,而Web Services基于一系列标准开放的技术规范和协议可以满足B2B集成的需求.但基于IIOP的通信却比依赖SOAP的通信有效得多.提出了一种CORBA应用与Web Services交互的方法以便高效实施B2B集成,这样既保护企业原来的投资又保证B2B集成新系统高效运行.     

The impact of microRNAs on protein output

MicroRNAs are endogenous approximately 23-nucleotide RNAs that can pair to sites in the messenger RNAs of protein-coding genes to downregulate the expression from these messages. MicroRNAs are known to influence the evolution and stability of many mRNAs, but their global impact on protein output had not been examined. Here we use quantitative mass spectrometry to measure the response of thousands of proteins after introducing microRNAs into cultured cells and after deleting mir-223 in mouse neutrophils. The identities of the responsive proteins indicate that targeting is primarily through seed-matched sites located within favourable predicted contexts in 3' untranslated regions. Hundreds of genes were directly repressed, albeit each to a modest degree, by individual microRNAs. Although some targets were repressed without detectable changes in mRNA levels, those translationally repressed by more than a third also displayed detectable mRNA destabilization, and, for the more highly repressed targets, mRNA destabilization usually comprised the major component of repression. The impact of microRNAs on the proteome indicated that for most interactions microRNAs act as rheostats to make fine-scale adjustments to protein output.     

特殊报文对标识字段比特随机性的影响研究

校园网出口流量存在大量的特殊报文（长度为40字节且标识字段值为0的口报文），本文运用信息论中熵的概念来定义随机测度，研究特殊报文对标识字段比特随机测度值的影响．实验结果表明，将特殊报文另行处理，则比特随机测度值不仅有明显提高而且变化幅度更小。     

A Partially Non-Cryptographic Security Routing Protocol in Mobile Ad Hoc Networks

In this paper, we propose a partially non-cryptographic security routing protocol （PNCSR） that protects both routing and data forwarding operations through the same reactive approach. PNCSR only apply public-key cryptographic system in managing token, but it doesn＇t utilize any cryptographic primitives on the routing messages. In PNCSR, each node is fair. Local neighboring nodes collaboratively monitor each other and sustain each other. It also uses a novel credit strategy which additively increases the token lifetime each time a node renews its token. We also analyze the storage, computation, and communication overhead of PNCSR, and provide a simple yet meaningful overhead comparison. Finally, the simulation results show the effectiveness of PNCSR in various situations.     

Study on the network delay of periodic information in the NCS based on EPA

The network delay of the periodic messages transmission in the network control system (NCS) based on Ethernet for plant automation (EPA) is analyzed from the theoretical and experimental perspective in this paper. The composition and the characteristics of the network delay of EPA periodic messages transmission in a subnet is studied through analyzing the information transmission regularity and EPA deterministic scheduling mechanism. On this basis, the queuing delay at communication schedule management entity (EPACSME) that is the most important component of network delay is analyzed, during which the formulas for the queuing delay of periodic messages and other real time parameters are proposed. Furthermore, an experiment is developed to test each component of network delay of periodic messages transmission in a EPA subnet. According to the experimental and the theoretical analysis, the conclusion is drawn that the delay during which the periodic messages wait for the periodic messages transmission time slice is the main factor that causes considerable network delay, and improvement method is presented.     

DNA sequence and expression of the B95-8 Epstein-Barr virus genome

The complete (172,282 base pairs) nucleotide sequence of the B95-8 strain of Epstein-Barr virus has been established using the dideoxynucleotide/M13 sequencing procedure. Many RNA polymerase II promoters have been mapped and the mRNAs from these promoters have been assigned to the latent or early/late productive virus cycles. Likely protein-coding regions have been identified and three of these have been shown to encode a ribonucleotide reductase, a DNA polymerase and two surface glycoproteins.