钙催化剂在生物降解脂肪族聚酯合成中的应用

生物降解高分子在环境保护以及组织工程、药物控制释放、骨固定等医药领域有着广泛的应用。特别是以聚丙交酷（PLA）、聚乙交酯（PGA）、聚。一己内酯（PCL）以及它们的共聚物为代表的化学合成生物降解高分子材料，由于具有优异的性能、可以大规模生产、成本较低等优点，得到了人们广泛的关注。作为生物医用材料，对无毒性的要求很严。而现在所用的脂肪族聚酯大都是用金属盐、金属有机化合物等作为催化剂合成出来的，不可避免残留一些催化剂所用的金属元素。研究表明，即使是已经获得美国FDA批准的，现在用得最普遍的辛酸亚锡所残留的锡也可能引起一些细胞毒性。因此对毒性小且活性高的催化剂的研究是非常有意义。钙离子对人体是没有毒性的，因而这几年已引起了人们的兴趣，但文献中报道的钙催化剂，如CaHZ等，催化活性尚不够让人满意。本文对高效的钙催化剂在生物降解脂肪族聚酯中的应用进行详细的研究，得到了一些有意义的结论：1、用EO和PO处理的有机氨钙催化剂（Ca／EO和Ca／PO）聚合了CL和LLA。发现CL聚合速度很快，M／I=650时70℃反应3h后收率已达到90％以上，LLA的聚合速度比CL要慢，M／I=650、70℃反应10h后收率才达到90％以上。以上聚合反应有明显的活性聚合的特点：反应初期Mv和收率和聚合时间呈线性关系；Mv在一定范围内和M／I成线性关系。2、用红外、原子吸收和核磁共振等分析手段阐明了有机氨钙催化剂的结构：结构，而且这两个催化剂的活性中心分别是均是Ca-O键。CL和LLA的开环聚合可能是以配位一插入的机理进行的。3、用C。／PO催化剂聚合LLA时有一定程度的消旋化反应发生，曳NMR研究表明相当于88％的LLA和12％外消旋以共聚。提高反应温度到110℃时比旋光度只有-125℃说明消旋化反应比较严重。4、用C。／PO催化剂先聚合CL再聚合LLA的方法合成了PCL-PLA两嵌段共聚物，并用泊NMR，13C NMR，GPC，DSC，WAXD进行了表征。其绝对和相对分子量可以通过M／I和投料比进行控制。定量碳谱图表明有较严重的消旋化反应发生，相当于84％的LLA和16％外消旋LA共聚。DSC和似XD分析表明，PLA段的分子量小时PLA段不结晶，当PLA段的分子量达到一定程度（3000以上）后PCL一PLA嵌段共聚物有相分离现象发生。5、以各种分子量的PEG为引发剂用氨钙催化剂和开环聚合CL，合成了一系列PCL-PEG-PCL三嵌段共聚物，并用妞NMR，laCNMR，GPC，DSC，做XD进行了表征。聚合物的结构可以通过改变PEG的分子量和CL／PEG投料比来调整。从DSC和wAXD分析可以得出以下几个结论：PCL-PEG-PCL嵌段共聚物有相分离现象发生，形成PCL和PEG微相区域；PEG段的结晶行为受先结晶的PCL段的影响；PCL段的分子量越大PEG段的Tc和Tm越低，其结晶度越低。6、以各种分子量的PEG为引发剂用氨钙催化剂80℃下开环聚合LLA24小时，合成了一系列PLA-PEG-PLA三嵌段共聚物，和别的催化剂比起来温度低得多，反应时间也短得多。可以通过改变PEG的分子量和CL／PEG投料比来调整聚合物的结构。DSC和WAXD分析表明，PLA-PEG-PLA三嵌段共聚物中PEG段的结晶能力受PLA段的影响非常大：当PEG段的分子量很小时（如1000）很难结晶；即使当PEG段的分子量较大时如果PLA段的分子量达到一定程度时PEG段同样也不结晶；而且PLA段的结晶行为受本身分子量的影响比较大，其Tc和伽随着分子量增加有较大的提高。7、合成了MPEG-PLA两嵌段共聚物，发现合成PLA段的分子量大的聚合物比较困难，MPEG-PCL两嵌段共聚物很难合成。DsC和WAXD分析表明，PLA段对MPEG段结晶有一定程度的影响，但是比三嵌段共聚物的影响要小得多。8、用荧光光谱和IHNMR研究了上面合成出的几个样品的胶束行为。发现cmc由大到小的顺序为MPEG（5000）-PLA（5100），PLA（3050）-PEG（4600）-PLA（3050），PCL（2270）-PEG（5000）-PCL（2270），PCL（4600）-PEG（4600）-PCL（4600）。PCL-PEG-PCL三嵌段共聚物在水中形成了具有核一壳结构的胶束。9、以苯甲醇处理的有机氨钙催化剂开环聚合了CL。泊NMR谱图表明得到的聚合物具有苯端基。这一结果为用硝苯基乙醇代替苯甲醇制备催化剂，然后开环聚合CL或LA得到硝基苯端基的脂肪族聚酯打下了实验基础。

脂肪族聚醚/聚酯-聚氨基酸嵌段聚合物的合成与表征

在最近的二三十年间，人们发现生物降解高分子在医药领域有很高的应用价值。如脂肪族聚酯，例如PGA（聚乙交酯），PLA（聚丙交脂），是一类重要的生物降解材料。由于它们的低免疫性和高的生物相容性，这一类材料被广泛应用于医药领域。众所周知，PEG（聚乙二醇）具有显著的生物相关性及优异的理化性质，包括：亲水性，溶于水及多种有机溶剂，无毒，不产生抗体及免疫性反应。这使得PEG被广泛应用于医药领域。同时它还被应用于与聚酯生成两亲性嵌段聚合物以改进聚酯的性能，生成具有一些新的特性的聚合物。在以上这些生物降解材料的应用过程中，人们发现需要在聚合物中引入功能基团以满足挂载药物，生物活性物质或在基因转移方面的应用。众所周知一些天然氨基酸具有活性基团，例如谷氨酸和天冬氨酸具有梭基，赖氨酸具有氨基，能够满足这类需求。于是我们就尝试着将聚氨基酸引入聚酯中，形成共聚物。同时共聚物中聚氨基酸段的存在改变了共聚物的降解性，使得它们能够被酶所降解。本文合成了端基为氨基的聚乙二醇单甲醚-聚丙交酯两嵌段聚合物（MPEG-PLA）以及将之应用于α-氨基酸-N-羧酸配（NCA）的开环聚合合成了聚乙二醇单甲醚一聚丙交酯-聚γ-苄基-L-谷氨酸三嵌段聚合物（MPEG-PLA-PBLG）。由于生物医用高分子材料用途的特殊性，需要聚合物中残留的催化剂易于除去或要求催化剂是无毒的。有机氨钙催化剂由于中心原子是人体中含量最多的金属元素一钙，因此非常适合于这一领域。本文运用氨钙催化剂合成了端基为氨基的聚。一己内酯并用为大分子引发剂，引发γ-苄基-L-谷氨酸NCA，合成了聚ε-己内酯-聚γ-苄基-L-谷氨酸两嵌段聚合物（PCL-PBLG）。三嵌段聚合物（MPEG-PLA-PBLG）以及两嵌段聚合物（PCL-PBIG）由泊NMR，IR，GPC，DSC进行了表征，证明了它们是所要制得的目标化合物。

可生物降解聚合物药物载体及其制备技术

药物释放体系因其具有提高药物的疗效，降低药物的毒副作用，减少药物的服用次数，拓宽给药途径等特点，而成为近几年来人们研究的热点。生物可降解高分子，由于它们在体内可以降解，降解产物可以被机体吸收或代谢，不存在积累在体内的危险，因此成为药物释放体系的载体的首选材料。特别是脂肪族聚酷类高分子，在与聚乙二醇形成嵌段共聚物后，不仅具有生物可降解性，而月＿大大地改善了材料与人体的生物相容性，作为药物载体材料时，延长了药物在体内的循环时间，降低了免疫响应性，引起了人们的极大兴趣。因此本论文主要是以MPEG-PLA两嵌段聚合物为药物的载体材料，详细研究了高分子量的MPEG-PLA两嵌段聚合物对紫杉醇的包裹，研究了MPEG-PLA和PLGA聚合物合金对胰岛素固体粉末的包裹，以及低分子量的MPEG-PLA的紫杉醇前药的合成、表征和由它制备而成的胶束的一些性质，取得了一些有意义的结果：1、采用改进的O／W乳液法，用高分子量的MPEG-PLA嵌段共聚物实现了对紫杉醇的纳米化包裹，并证实了聚合物的分子量对所制备的纳米微球的粒径的影响：分子量越大，粒径越大。同时发现了微球粒径越小，药物的包裹量越低。2、用扫描电镜（SEM）、光电子能谱（XPS）、差热分析（DSC）对纳米微球进行了分析和测定，结果表明，微球的尺寸在30Om-800nm范围，紫杉醇在纳米微球的表面几乎不存在，而是以无定形的状态分布在纳米微球中。3、对纳米微球中紫杉醇体外释放行为进行了侧定。它们显现出了明显的双相行为，即在初期释放速度很快，随后的释放速度变慢。同时，研究了MPEG-PLA的分子量对释放行为的影响：聚合物分子量越大，紫杉醇释放的速度就越慢。4、用固体粉末法和双乳液法对胰岛素进行了包裹，其中固体粉末法采用的是PLGA和MPEG-PLA两聚合物的混合溶液对纳米胰岛素颗粒进行了包裹，包裹率分析表明：固体粉末法对药物的包裹率高于双乳液法。所得的微球都是很好的球形，其尺寸在1-3um左右，它的剖面是核壳结构，胰岛素以晶粒的形式被包裹在微球中间。5、对固体粉末法和双乳液法制备的微球的体外释放行为进行了对比，发现由两种聚合物合金制备的微球的暴释现象得到了缓解，同时发现两种聚合物的配比不一样，其暴释缓解的程度不一样。6、以辛酸亚锡为催化剂成功地合成了低分子量的MPEG-PLA两嵌段聚合物。二经基乙酸配与过量的叔丁醇在DMAP存在下反应，成功制得了二轻基乙酸单叔丁酷。MPEG-PLA的端经基与二经基乙酸单叔丁酷在DCC参与下脱水酷化再将叔丁基去保护，便得到端梭基的MPEG-PLA。7、端基为梭基的MPEG-PLA与紫杉醇的2’-羟基或7-轻基进行了酷化反应，制备出MPEG-PLA-紫杉醇前药。8、制备了四种低分子量的MPEG-PLA-紫杉醇前药，用1H NMR和GPC进行了表征分析。紫杉醇前药中紫杉醇的含量最高可达到20％，依赖于MPEG-PLA中PLA段的长度。9、用荧光探针法考察了MPEG-PLA两嵌段聚合物和MPEG-PLA-紫杉醇前药的胶束化行为，发现前药总比相对应的两嵌段聚合物有更低的临界胶束浓度（CMC）。用透射电镜观察了胶束的形貌和尺寸大小，以及接药前后胶束尺寸的变化。发现都是很好的球状胶束，MPEG-PLA两嵌段聚合物和MPEG-PLA-紫杉醇前药胶束的平均粒径分别为25±3nm和33士Znm，说明聚合物在接药后，随着疏水部分分子量的增加，所形成的胶束粒径也增大。

带侧羧基的脂肪族生物降解聚合物

生物降解脂肪族聚酷如聚乙交醋（PGA）、聚丙交醋（PLA）、聚。一己内酷（PCL）以及它们的共聚物由于具有良好的生物相容性和生物降解性而在外科手术缝合线、组织工程、药物控制释放、骨固定等领域得到很多应用。但是，它们自身缺乏功能基团，亲水性差，因而在应用上受到很大限制。因此，含有功能侧基生物降解聚合物的制备在过去十年中受到大家极大的关注。功能基团的引入对于调节聚合物的性能如：亲水性、生物降解性和药物的渗透性等非常重要。需要特别指出的是，功能基团的引入为把药物和其它生物活性物质与聚合物结合进而扩大聚合物的应用范围提供了机会。本文合成了几个功能化单体并且通过共聚的方法制备了几种新型的两亲性功能化聚合物。这些改性后的聚合物可以通过化学键接上药物或者其它生物活性物质，有望作为靶向控释药物载体和智能化的组织工程支架材料。具体的研究结果如下：1．以2，2-二羟甲基丙酸节酷为功能单体，通过两步法成功合成了一系列新的带功能基团的聚酷酞胺，并通过1H NMR和FTIR对聚合物的化学结构进行了表征，DSC结果表明所合成的聚酯酰胺的Tm和Tg分别在150℃和0℃左右；2．合成了功能化的环状单体（35）-3-［（苄氧羰基）乙基」吗啉-2，5-二酮（BEMD），并以PEG作为引发剂，Sn（Oct）2作为催化剂，通过L一LA和BEMD的开环共聚合得到共聚物PLGBG-PEG-PLGBG；随后用10％铭碳催化氢化得到带有侧梭基的两亲性嵌段共聚物PLGG-PEG-PLGG和其它两亲性嵌段共聚物一样，PLGG-PEG-PLGG在水溶液中能够自组装成胶束，用花作为荧光探针，通过荧光光谱法研究了其形成胶束的过程并测定了它们的临界胶束浓度，发现在总的分子量大致相当的情况下，PLGG-PEG4600-PLGG比PLGG-PEG2000-PLGG有较高的临界胶束浓度；场发射电子显微镜表征结果显示胶束具有均一的球形特征，动态光散射结果表明该胶束具有较窄的单峰粒径分布；蛋白酶K溶液中的降解研究表明带有侧梭基的PLGG-PEG-PLGG比PLA具有更快的降解速率；人胚关节软骨细胞培养结果表明所合成的聚合物PLGG-PEG-PLGG显示出较好的细胞相容性。3．在缩合剂DCC和催化剂DMAP存在下，带有侧梭基的两亲性嵌段共聚物PLGOPEG-PLGG和紫杉醇发生缩合反应得到两亲性嵌段共聚物一紫杉醇键合药P（LGG-paclitaxel）-PEG-P（LGG-paclitaxel）。它具有两亲性嵌段共聚物的性质，能够自组装成胶束，场发射电子显微镜表征结果表明胶束具有均一的球形特征，动态光散射结果表明该胶束具有较窄的粒径分布，平均粒径为119.4nm。该胶束的药物释放具有pH敏感性，酸性环境中比生理环境中（pH＝7.4）具有较快的释放速率。P（LGG-Paclitaxel）-PEG-P（LGG-paclitaxel）胶束的壳层由良好亲水性的PEG组成，避免了胶束纳米粒子在血液循环中被人体网状内皮系统吞噬，保证有充足的时间通过EPR效应在肿瘤部位聚集，进而通过细胞内吞进入细胞并在细胞内的酸性环境中释放药物，进一步的研究工作有待深入进行。4．合成了功能化的环状碳酸酷单体MBC，以MPEG作为引发剂，ZnEt2作为催化剂，LLA和MBC发生开环共聚合，以较高的转化率，得到高分子量共聚物MPEG-b-P（LA-co-MBC）。13C NMR表明LLA和确c发生了无规共聚合；DSC征结果表明MPEG-b-P（LA-co-MBC）为无定型态聚合物，Tg在20-50℃之间，随着MBc含量的增加而降低；MPEG-b-P（LA-co-MBC）脱保护后得到带侧梭基的MPEG-b-P（LA-co-MCC），它的Tg明显提高，可能是聚合物侧梭基之间强的氢键作用力以及梭基对水解反应的催化作用造成的；脱保护前后的共聚物在蛋白酶K溶液中的降解研究表明，MPEG-b-P（LA-co-MCC）的降解速率大于MPEG-b-P（LA-co-MBC）的降解速率；人胚关节软骨细胞培养结果表明，所合成的MPEG-b-P（LA-co-MCC）是一种具有良好生物相容性的新型生物降解材料。5．利用本实验室开发的一种新型有机氨锯引发剂Sr-PO在温和的条件下通过顺序加料聚合的方法合成了新的嵌段共聚物PCL-b-PMBC。WAXD结果表明 PCL-b-PMBc中PCL的衍射峰均可观察到，只是衍射峰的强度随着PMBC含量的增加而减弱。DSC结果表明PCL-b-PMBC中PCL的Tm在57到52℃之间，并且随着PMBC含量的增加而降低。PCL-b-PMBC的玻璃化转变在-41.6 到-23.3℃之间，随着PMBC含量的增加而增加，这表明PMBC和PCL之间 有着强的相互作用，尽管两段不是完全相容的。PCL-b-PMBC的侧节醋在10％把碳催化下氢化还原为带侧梭基的PCL-b-PMCC后，衍射峰和结晶焙大大降低，说明侧梭基的存在使得分子链间有着强的氢键相互作用而不利于结晶。由以上分析可知，PCL-b-PMCC侧梭基的存在将会使共聚物的降解速度大大提高，而且因为功能梭基的存在可以使共聚物通过化学键连接上药物、短肤、寡糖或者其它生物活性物质，从而扩大该聚合物在生物医学领域的应用范围。

流媒体分发与传输关键技术研究

随着Internet技术的飞速发展，流媒体分发技术取得了长足的进步，同时，日益增加的用户、视频数据和流媒体交互式需求，也给大规模流媒体分发服务带来了新的挑战。另外一方面，随着宽带无线接入技术发展的日新月异，如何有效利用多种接入方式为用户提供更高质量的流媒体服务是当前通信技术领域迫切需要解决的问题。本文对基于应用层支持交互式的P2P流媒体分发技术及基于传输层支持Multihoming的SCTP流媒体传输技术进行了相关研究，主要贡献和创新点如下： 第一、提出了一种支持随机访问的协作式P2P流媒体分发方案。该方案采用平衡二叉树将媒体对象进行分布式分段预取缓存，用于媒体流快速定位，利用缓存重叠机制构建非结构化网络，用于节点间常规媒体流分发。分别设计了媒体预取算法及邻居节点搜索算法，给出了节点失效恢复策略及支持随机访问的协作过程。仿真试验结果表明，在随机访问及网络波动过程中，该方案能够提供高平滑质量的P2P媒体流服务。 第二、提出了一种基于数据驱动及分布式存储的P2P VoD解决方案。该方案融合了平衡多叉树与基于数据驱动的随机图网络两种拓扑。利用gossip算法构建和维护随机图网络中的邻居节点关系，采用数据驱动机制进行邻居节点间媒体流的分发，进一步降低了源服务器的负载。设计了一种基于平衡多叉树的分布式预取缓存算法，提高了随机访问的搜索效率。仿真试验结果和分析表明，两种网络拓扑的协作机制有效地解决了P2P VoD中视频传输及交互式操作问题。 第三、设计和实现了一种基于Trace驱动及SCTP的MPEG-4视频传输评估平台Evalvid-SCTP。Evalvid-SCTP提供了在仿真环境下SCTP流媒体实时传输及视频质量评估的解决方案。在Multihoming环境下，Evalvid-SCTP可以有效地分析SCTP在不同网络条件和负载下的流媒体传输行为特征和传输质量。 第四、提出了SCTP流媒体单路径传输最佳协议参数配置策略及多路径并行传输策略。评估了在单路径传输机制下快速重传策略、超时重传策略、路径故障检测门限值设置，三者配合时在多种网络条件下的流媒体传输性能，并综合以上各种发现提出了在不同的路径条件下应该采取的重传路径选择策略以及路径故障检测门限值设置方案。评估了在多路径并行传输下融合SCTP部分可靠特性的流媒体传输性能，提出了针对流媒体传输，多路径并行传输应采取的策略。

生姜化感作用机理及其栽培模式研究

近年来，随着对作物重茬（连年种植）障碍原因的深入研究，植物的化感作用越来越受到国内外众多学者的重视。而作为重要调料和药用植物的生姜，其连作障碍也备受关注，系统地研究生姜化感作用将有助于理解和最终解决生姜连作障碍问题。本文通过研究生姜不同部位、不同浓度的水浸液对与其间作的两个物种（大豆和四季葱）种子的萌发及幼苗生长的影响，从而证明生姜化感作用的存在；并通过温室盆栽实验研究了生姜的自毒作用（即研究生姜不同部位、不同浓度的水浸液对其幼苗的形态、生理生化、光合作用、土壤酶、土壤微生物多样性及土壤养分的影响），从而揭示生姜退化和衰老的机制，并为生姜筛选出合适的间作物种提供科学依据，对生姜连作障碍提出科学的解决方法。主要研究结果如下： 1. 与对照相比，生姜所有部位（根茎、茎、叶）、所有浓度（10、20、40、 80 g l-1）的水浸液均抑制了大豆种子和葱籽的萌发率、幼苗生长、水分吸收和脂肪酶活性，并且其抑制程度随着水浸液浓度的增加而增强，其生姜各部位水浸液抑制效应的强弱顺序为茎＞叶＞根茎。这一结果表明生姜根茎、茎、叶含有能够抑制大豆种子和葱籽种子萌发和幼苗生长的水溶性化感物质。根茎是生姜的主要收获部位，而生姜的残株（主要是茎和叶）应该从大田中处理掉以减轻其抑制效应。生姜水浸液中主要化感成分包括：根茎水浸液中主要是丁香酸和伞花内脂；茎水浸液中主要是阿魏酸，且其含量最高为73.4 ug/g；叶水浸液中除了阿魏酸，其他六种物质均检测出来，但含量较高的主要有丁香酸、伞花内脂和香豆酸。 2. 生姜茎和叶不同浓度的水浸液均显著抑制了生姜幼苗的株高、每株叶片数和叶面积，其抑制程度随着水浸液浓度的增加而有所增强，而生姜幼苗每株分枝数差异不显著；同时生姜水浸液也极大程度地影响了生姜幼苗的生物量（包括地下生物量、地上生物量和总生物量，均为鲜重）。在同一浓度下，茎水浸液对生姜幼苗形态指标及生物量指标均显示出最强的抑制作用，叶水浸液次之，根茎水浸液最弱。与对照相比，低浓度的生姜根茎水浸液提高了生姜幼苗叶片内四种抗氧化酶（SOD、POD、CAT、APX）活性，高浓度的根茎水浸液抑制了四种抗氧化酶活性，而茎和叶水浸液均随着浓度的增加而抑制了四种抗氧化酶活性，三种水浸液均随着浓度的增加降低了生姜幼苗叶片内叶绿素的含量，而增加了生姜幼苗叶片的相对电导率和丙二醛含量。同时，三种水浸液均随着浓度的增加降低了生姜幼苗的光合参数（包括胞间CO2浓度、气孔导度、蒸腾速率及净光合速率）。 3. 三种生姜水浸液对所测六种土壤酶活性均产生了不同程度的影响，其中影响最大的是酸性磷酸酶和蔗糖酶，在10 g l-1 时就达到了显著水平，并且所有酶均有随着水浸液浓度增加而增大的趋势；相同部位的水浸液随着浓度的增加，细菌和真菌的数量呈增加趋势，而放线菌的数量呈减少趋势；三种生姜水浸液均随着浓度的增加降低了土壤中有机质的含量，加剧了土壤中硝态氮含量的积累，根茎水浸液对土壤有效磷、速效钾和铵态氮均显示出低浓度提高其含量而高浓度降低其含量的趋势，而茎和叶水浸液则随着浓度的增加均降低了其含量。 4. 与生姜单作相比，所有间作系统均在旺盛生长期和收获期不同程度地提高了土壤酶活性，同时也增加了土壤细菌数量及土壤微生物总数但不显著；所有间作系统在旺盛生长期和收获期均不同程度地影响了土壤真菌及放线菌数量（增加或减少），所有间作系统间的多样性指数差异不显著，除了旺盛生长期四种作物（生姜-大豆-四季葱-大蒜）的间作模式显著降低了多样性指数，其值仅为生姜单作的33.18%；生姜与大豆间作不仅提高了19.6%的生姜产量而且获得了较好的经济效益，并且，所有间作系统均显著抑制了生姜姜瘟病的发生。 5. 不同栽培模式不同程度地影响了收获期生姜的株高、分枝数、根茎产量及内在品质。其中处理2显著地促进了生姜的分枝（10.5%），同时处理2、3和4也促进了生姜的生长（株高分别增加了15.0%、11.4%和14.0%），并且这三个处理提高了生姜的产量；处理2和3能有效提高生姜块茎中维生素C（分别较单作生姜显著提高了3.29%和4.05%）、处理3显著提高了可溶性糖（8.2%）、姜辣素（4.6%）和蛋白质等有益物质的含量，降低硝酸盐有害物质的含量（处理2显著降低了14.0%），改善了姜块的外观和内在品质。并且，生姜与大豆间作具有最高的纯收入和产投比，分别较生姜单作提高了24.80%和8.8%。Recently, allelopathy has been more and more paid attentions by national and foreign scholars with profound research on reasons of crop replanted (continuous planted) obstacle. Ginger rhizome is valuable all over the world either as a spice or herbal medicine and ginger replanted obstacle is also paid attentions. Systematic research on ginger allelopathy will contribute to understanding and ultimate solving problem of ginger replanted obstacle. The effects of ginger aqueous extracts with different parts and concentrations on seed germination and early seedling growth of soybean and chive were studied in this article to testify that ginger existed allelopathy. Furthermore, ginger autotoxicity was also studied by pot experiment in greenhouse (namely research on effects of ginger aqueous extracts with different parts and concentrations on morphological indexes, physiological and biochemical indexes, photosynthesis, soil enzymes, soil microbial diversity and soil nutrients) to reveal mechanism of ginger degeneration and senescence, provide scientific basis for selecting appropriate intercropping species and put forward scientific resolvent for ginger replanted obstacle. The main results were as follows: 1. All aqueous extracts at all concentrations inhibited seed germination, seedling growth, water uptake and lipase activity of soybean and chive compared with the control, and the degree of inhibition increased with the incremental extracts concentration. The degree of toxicity of different ginger plant parts can be classified in order of decreasing inhibition as stem＞leaf＞rhizome. The results of this study suggested that rhizome, stem and leaf of ginger contained water soluble allelochemicals which could inhibit seed germination and seedling growth of soybean and chive. The rhizome is the main harvested part of ginger. The residue (mainly stems and leaves) of the ginger plant should be removed from the field so as to diminish its inhibitory effect. The main allelopathic components of three kind of aqueous extracts were as follows: Rhizome extract chiefly contained syringic acid and vmbelliferone and stem extract mainly contained frulic acid whose content was the highest (73.4 ug/g). The other six substances were detected except of frulic acid, but only contents of syringic acid, vmbelliferone and p-coumaric acid were higher. 2. Stem and leaf aqueous extracts of ginger with different concentrations significantly inhibited plant height, leaf numbers per plant and leaf area, and the degree of inhibition increased with the incremental extracts concentration. However, tiller number per plant of ginger seedling showed no significant difference. At the same time, ginger aqueous extracts also influenced biomass including under-ground biomass, above-ground biomass and total biomass (fresh weight) to a large extent. Under the same concentration, stem aqueous extract showed the mostly inhibitory effect on morphological indexes and biomass indexes of ginger seedling. Rhizome aqueous extract showed the leastly inhibitory effect and leaf aqueous extract was intervenient. Enhanced concentration of ginger aqueous extracts significantly reduced total chlorophyll content, accompanying with increases in memberane permeability (REL) and lipid peroxidation (MDA). Compared with the control, rhizome ginger aqueous extract of lower concentration (10 g l-1) increased the activities of major antioxidant enzymes (superoxide dismutase, SOD; peroxidase, POD; catalase, CAT; ascorbate peroxidase, APX) of ginger leaf tissue and higher concentration inhibited the activities of four antioxidant enzymes. However, stem and leaf aqueous extract inhibited the activities of four antioxidant enzymes with increase in concentration. Meanwhile, enhanced concentration of ginger aqueous extracts significantly reduced photo-parameters of ginger seedling (including CO2 concentration, stoma conductivity, net photosynthesis rate and transpiration rate). 3. Rhizome, stem and leaf ginger aqueous extract showed different effect on six soil enzyme activities, and acid phosphatase and invertase showed significant effect when aqueous extract concentration got 10 g l-1. Furthermore, six soil enzyme activities increased with increase in aqueous extract concentration. Bcterial and fungi number tended to increase while antinomyces tented to decrease with the increase in aqueous extract concentration of identical part. Ginger aqueous extracts reduced soil organic matter content with increased concentration, accompanying with NO3-—N accumulation in soil. Rhizome aqueous extract showed the same tendency for available P, available K and NH4+—N, namely lower concentration increased their contents in soil and higher concentration reduced their contents. While stem and leaf aqueous extracts reduced their contents with the increamental concentration. 4. All intercropping systems increased soil enzyme activities to different extent both at VGS and at HS compared to solo ginger. All intercropping systems increased the colony numbers of soil bacteria and total of soil microbe but not significantly either at VGS or at HS. All intercropping systems increased the colony numbers of soil fungi and actinomytes to a different extent (increase or decrease) both at VGS and at HS. For DI, difference between all cultivation patterns and S-G was not significant either at VGS or at HS except that G-S-C-G whose value was only 33.18% of S-G at VGS significantly decreased. G-S not only increased ginger yield by 19.6% but also obtained better economic benefit. Furthermore, all intercropping systems significantly inhibited occurrence of bacterial wilt of ginger. 5. Different cultivated pattern influenced plant height, tiller numbers, rhizome yields and intrinsic quality of ginger. Treatment 2 significantly facilitated tiller occurring (10.5%). Treatment 2, 3 and 4 promoted ginger growth (plant height respectively increased 15.0%、11.4% and 14.0%) and enhanced rhizome yields. Treatment 2 and 3 effectively increased vitamin C content (significantly increased 3.29% and 4.05% compared to solo ginger). Treatment 3 significantly increased contents of beneficial substances such as soluble sugar (8.2%), gingerols (4.6%) and protein. Treatment 2 significantly decreased contents of deleterious substance namely nitrate (14.0%) and improved appearance and intrinsic quality of ginger rhizome. Furthermore, treatment 2 (ginger/soybean intercropping) could obtain better economic benefit and showed the highest net income and ratio of benefit and cost whose values respectively increased by 24.80% and 8.8% compared to solo ginger.

用CR-39对空间重离子的鉴别模型(英文)

根据重离子在CR39中能量损失率公式,建立了一个鉴别空间重离子的数学模型LET=cZdRb.通过传能线密度与剩余射程之间的关系曲线,获得了该模型的系数.在实验中发现的CR39蚀刻率与离子有限传能线密度的关系VT=A·(REL)BE<350,被用来与该数学模型相关联,并得到一等式R=A0.0455Z3.18V-1T.最终,借助于标定实验得到了离子鉴别公式Z3.18=64541.08+2.53(dR/dV-1T).

8B的库仑离解和天体物理学S17因子的测量

对太阳中微子问题，即在地球上观测到的太阳中微子通量同标准太阳模型理论预言之间的巨大差异的解释，依赖于~7Be(p,γ)~8B反应在低能区的反应截面，即S_(17)因子，而目前测量结果中过大的不确定性(>20%)，使得有必要对这一因子重新给予精确的测定。作为对直接质子俘获截面测量的替代，库仓离解方法被利用以获取S_(17)因子。采用入射能量E(~8B) = 254MeV/u的放射性~8B次级束流，并利用其大接收度磁谱仪KaoS，我们在GSI进行的实验通过对反应事例的逐个鉴别和不变质量分析，得到对应于S_(17)因子的质子俘获反应~7Be(p,γ)~8B的时间反演过程~8B(p,γ)~7Be的反应总截面σ_(CD) = 287 ± 15mb，以及作为反应碎片间相对动能函数的微分反应截面(dσ_(CD))/(dE_(rel))(E_(rel))。通过对微分反应截面中各种多级跃迁成份的分离，并经由细致平衡原理，我们计算得到了S_(17)因子，并在理论计算的帮助下，将其外推到太阳能区：S_(17)(0) = 21.2 ± 0.9eV·b及S_(17)(20KeV) = 20.6 ±0.9eV·b。

Biodegradable Interpolyelectrolyte Complexes Based on Methoxy Poly(ethylene glycol)-b-poly(alpha,L-glutamic acid) and Chitosan

We synthesized methoxy poly(ethylene glycol)-b-poly(alpha,L-glutamic acid) (mPEGGA) diblock copolymer by ring-opening polymerization of N-carboxy anhydride of gamma-benzyl-L-glutamate (NCA) using amino-terminated methoxy polyethylene glycol (mPEG) as macroinitiator. Polyelectrolyte complexation between mPEGGA as neutral-block-polyanion and chitosan (CS) as polycation has been scrutinized in aqueous solution as well as in the solid state.

A Biodegradable Diblcok Copolymer Poly(ethylene glycol)-block-poly(L-lactide-co-2-methyl-2-carboxyl-propylene carbonate): Docetaxel and RGD Conjugation

A diblcok copolymer monomethoxy poly (ethylene glycol)-block-poly(L-lactide-co-2-methyl-2-carboxyl-propylene carbonate) (MPEG-b-P(LA-co-MCC)) was obtained by copolymerization of L-lactide (LA) and 2-methyl-2-benzoxycarbonyl-propylene carbonate (MBC) and subsequent catalytic hydrogenation. The pendant carboxyl groups of the copolymer MPEG-b-P(LA-co-MCC) were conjugated with antitumor drug docetaxel and tripeptide arginine-glycine-aspartic acid (RGD), respectively.

The Study of Electroactive Block Copolymer Containing Aniline Pentamer Isolated from Different Solvents

For the films and powder of polymers containing conductive oligomer are usually obtained from solution, the choice of better solvents for the regular arrangement of oligomers is very important for the higher conductivity. Because of the poor solubility of the oligomers, it is difficult to study the arrangement directly in most common solvents, so, we synthesized a triblock copolymer, mPEG2k-aniline pentamer-mPEG2k, as the model to investigate the arrangement-solvent relationship. For the poor solubility of the AP block in common solvents, the copolymer self-assembled into spheric micelles in toluene and into lamellar crystals in water and THF. The crystallinity (X-c) and crystallization temperature (T-c) values of mPEG blocks in powders prepared from different solvents differed obviously, which may be the effect of different self-assembled structures. From the two-phase model of one-dimensional electron density correlation function of SAXS, the long period of copolymer prepared from THF was presumably equal to the long period of pure mPEG plus the chain length of AP, which demonstrates that the AP blocks arrange regularly in the noncrystalline regions.

SYNTHESIS AND CHARACTERIZATION OF A CROSSLINKING POLYETHYLENIMINE AS SMART GENE CARRIER AND EFFECTS OF PEGYLATION DEGREE

A smart biodegradable cationic polymer (CBA-PEI) based on the disulfide bond-containing cross-linker cystamine bisacrylamide (CBA) and low molecular weight branched polyethylenimine (1800-Da, PEI1800) was successfully synthesized by Michael addition reaction in our recent study. Furthermore, a series of copolymers (CBA-PEI-PEG) with different PEGylation degree were obtained by the mPEG-SPA (5000-Da) reacting with CBA-PEI at various weight ratios directly. The molecular structures of the resulting polymers CBA-PEI and CBA-PEI-PEG were evaluated by nuclear magnetic resonance spectroscopy (H-1-NMR) and capillary viscosity measurements, all of which had successfully verified formation of the copolymers. The polymer/DNA complexes based on CBA-PEI and CBA-PEI-PEG were measured by dynamic light scattering and gel retardation assay. The results showed that the particle size and zeta potential of complexes were reduced with increasing amount of PEG grafting, even no particle formation. The particle size of CBA-PEI/DNA complexes was in range of 103.1 to 129.1 nm, and the zeta potential was in range of 14.2 to 24.3 mV above the 2:1 weight ratio. In the same measure condition, the particle size of CBA-PEI-PEG complexes was reduced to a range of 32.2 to 55 nm, and the zeta potential was in range of 9.3 to 13.8 mV at the 2:1 weight ratio.

Physical diffusion and electron-transfer dynamics of electroactive solutes in polymer electrolytes .2. Effect of the ionic size of supporting electrolytes

The diffusion coefficients(D-app) and the heterogeneous electron-transfer rate constants(k(s)) for ferrocene in MPEG/salt electrolytes were determined by using steady-state voltammetry. The temperature dependence of the two parameters obeys the Arrhenius equation. The effect of the ionic size of six supporting electrolytes on diffusion and electron transfer dynamics of ferrocene was discussed.

Physical diffusion and electron-transfer dynamics of electroactive solutes in polymer electrolytes .1. Effect of the nature of electroactive solutes

The diffusion coefficients(D-app) and the heterogeneous electron-transfer rate constants(k(s)) for ferrocene and its seven derivatives in MPEG/LiClO4 electrolyte were determined by using steady-state voltammetry. The two parameters increase with increasing temperature, indicating Arrhenius behavior. The effects of the nature of electroactive solute molecules on D-app, k(s), and the half-wave potentials(E-1/2) are discussed.

Molecular cloning and expression of a Relish gene in Chinese mitten crab Eriocheir sinensis

P>NF-kappa B is a B-cell specific transcription factor that plays crucial roles in inflammation, immunity, apoptosis, development and differentiation. In the present study, a novel NF-kappa B-like transcription factor Relish was cloned from Chinese mitten crab Eriocheir sinensis (designated as EsRelish) by rapid amplification of cDNA ends (RACE) technique based on expressed sequence tag (EST). The full-length cDNA of EsRelish was of 5034 bp, consisting of a 5' untranslated region (UTR) of 57 bp, a 3' UTR of 1335 bp with two mRNA instability motifs (ATTTA), a polyadenylation signal sequence (AATAAA) and a poly (A) tail, and an open reading frame (ORF) of 3645 bp encoding a polypeptide of 1214 amino acids with a calculated molecular mass of 134.8 kDa and a theoretical isoelectric point of 5.26. There were a typical Rel homology domain (RHD), two nuclear localization signal (NLS) sequences (KR), an inhibitor kappa B (I kappa B)-like domain with six ankyrin repeats, a PEST region and a death domain in the deduced amino acid sequence of EsRelish. Conserved domain, higher similarity with other Rel/NF-kappa Bs and phylogenetic analysis suggested that EsRelish was a member of the NF-kappa B family. Quantitative real-time RT-PCR was employed to detect the mRNA transcripts of EsRelish in different tissues and its temporal expression in hemocytes of E. sinensis challenged with Pichia methanolica and Listonella anguillarum. The EsRelish mRNA was found to be constitutively expressed in a wide range of tissues. It could be mainly detected in the hemocytes, gonad and hepatopancreas, and less degree in the gill, muscle and heart. The expression level of EsRelish mRNA in hemocytes was up-regulated from at 3, 6, 9 and 12 h after P. methanolica challenge. In L. anguillarum challenge, it was up-regulated at 9, 12 and 24 h. The results collectively indicated that EsRelish was potentially involved in the immune response against fungus and bacteria.