缺硫对万寿菊镉积累的影响

采用营养液培养法,研究了缺硫对万寿菊(Tagetes erecta)各器官镉积累的影响,以及巯基化合物和有机酸等在各器官镉积累中的作用。结果表明:0.1 mg.L-1镉处理7 d,缺硫处理显著降低了植物根、茎和叶中的镉含量,较对照分别降低了47%、38%和61%;缺硫对植物体内半胱氨酸、γ-谷氨酰半胱氨酸、谷胱甘肽和有机酸的合成没有显著影响,而且3种巯基化合物的含量都很低;缺硫植物根部合成的植物络合素的量显著降低,这可能是植物体内镉积累减少的主要原因;在植物的各器官中,叶片中的有机酸含量最高,而在叶片中未检测到植物络合素,由此可推断,叶片中积累的镉主要与有机酸结合;缺硫影响了根部植物络合素的合成,进而降低了植物体内镉的积累,而缺硫没有影响植物体内有机酸的合成,有机酸可能仅是参与植物组织中与镉的络合作用。

基于半监督学习的P2P协议识别

协议识别是进行有效的网络管理与控制的重要条件，由于新的P2P软件（以Skype,Emule，BitComet，迅雷为代表）开始使用加密协议和协议伪装等技术手段来防止被网管探测、识别、封堵，传统的根据协议特征码来识别的方式已经难以识别这些软件产生的流量。基于流量特征的P2P协议识别的方法是目前研究的主要方向，将机器学习的理论与模型运用到协议识别领域是发展的一个趋势。通过对传输层数据包(包括TCP和UDP数据包)进行分析，并结合P2P系统所表现出来的流量特征，来识别某个网络流是否属于P2P。这类方法包括：TCP/UDP端口识别技术、网络直径分析技术、节点角色分析技术、协议对分析技术和地址端口对分析技术等，但是其准确性和识别率不如特征码识别。本文就基于半监督聚类的模型运用到识别具体P2P应用的可能性进行了分析与实验，提出了一种基于Newton-Raphson方法学习特征权值矩阵的训练的办法，在依据P2P应用特征选取连接特征的基础上进一步提高系统识别准确率和召回率。在本文的实验环境下，针对具体的BitComet和Emule应用的识别器的识别率和召回率均达到了85%左右，在加密协议的识别上取得了不错的效果。如何优化系统的识别准确率和召回率，提高系统效率是本文重点研究并试图解决的问题，主要包括以下三个方面的成果：一、实验并分析了基于半监督学习的聚类模型在加密P2P应用识别上的效果，同时总结了一套分析P2P协议特征的办法。二、将Newton-Raphson方法引入到连接特征的选取上，将特征权值矩阵用于距离的计算，进一步提高了训练和识别的效果。三、基于KD-Tree的识别器的实现使得整个在线识别过程能在内核的协议层高效实现，有效的控制了系统的计算复杂度。

Improved Melting Strength of Polypropylene by Reactive Compounding With Ultrafine Full-Vulcanized Polybutadiene Rubber (UFBR) Particles

Ultrafine full-vulcanized polybutadiene rubber (UFBR) in particle sizes of ca. 50-100 nm has been used for modifying mechanical and processing performances of polypropylene (PP), and PP-g-maleic anhydride (PP-MA) has been used as a compatibilizer for enhancing the interfacial adhesion between the two components. The results show that PP/UFBR possesses rheological behaviors such as highly branched PP when UFBR content in blends reaches 10 wt%, while in contrast, the much low content of UFBR combining small amount of PP-MA endows the material with rheological characteristics of high melt strength materials like highly branched PP.

Correlation analysis of the structures and gas-liquid chromatographic retention indices of amines

Quantitative structure-retention relationship(QSRR) was studied for amines to gas-liquid chromatography on three stationary phases of different polarities with the topological indices A(m) (A(m1), A(m2), A(m3)) and gravitational index GI. The algorithm of "Leaps and Bounds" was performed for selection of the variables. And the multi-regression and the quasi-Newton neural networks were employed for the calculation with better results.

Structure-activity relationships for antiplasmodial activity among aminoquinolines

The extended gravitational index G(Q) and quantum-chemical descriptors were calculated for the relationship analysis of aminoquinolines. An evolutionary algorithm was described for variable selection and building QSAR models. And the quasi-newton neural networks were employed with better results.

Self-assembled monolayer growth of phospholipids on hydrophobic surface toward mimetic biomembranes: Scanning probe microscopy study

Atomic force microscopy (AFM) and lateral force microscopy (LFM) were used simultaneously to analyze a model membrane bilayer structure consisting of a phospholipid outer monolayer deposited onto organosilane-derivatized mica surfaces, which were constructed by using painting and self-assembly methods. The phospholipid used as outer monolayer was dimyristoylphosphatidylcholine (DMPC). The hydrocarbon-covered substrate that formed the inner half bilayer was composed of a self-assembly monolayer (SAM) of octadecyltrichloroorganosilane (OTS) on mica. SAMs of DMPC were formed by exposing hydrophobic mica to a solution of DMPC in decane/isobutanol and subsequently immersing into pure water. AFM images of samples immersed in solution for varying exposure times showed that before forming a complete monolayer the molecules aggregated into dense islands (2.2-2.6 nm high) on the surface. The islands had a compact and rounded morphology. LFM, coupled with topographic data obtained with the atomic force mode, had made possible the distinction between DMPC and OTS. The rate constant of DMPC growth was calculated. This is the first systematic study of the SAM formation of DMPC by AFM and LFM imaging. It reveals more direct information about the film morphology than previous studies with conventional surface analytical techniques such as infrared spectroscopy, X-ray, or fluorescence microscopy.

Chemical Constituents of a Marine-Derived Endophytic Fungus Penicillium commune G2M

Cultivation of the endophytic fungus Penicillium commune, which was isolated from the semi-mangrove plant Hibiscus tiliaceus, afforded one new compound 1-O-(2,4-dihydroxy-6-methylbenzoyl)-glycerol (1) along with thirteen known products, including 1-O-acetylglycerol (2), N-acetyltryptophan (3), 3-indolylacetic acid methyl ester (4), 1-(2,4-dihydroxy-3,5-dimethylphenyl)ethanone (5), 2-(2,5-dihydroxyphenyl)acetic acid (6), (4R,5S)-5-hydroxyhexan-4-olide (7), thymidine (8), uracil (9), thymine (10), ergosterol (11), beta-sitosterol (12), beta-daucosterol (13), and ergosta-7,22-dien-3 beta,5 alpha,6 beta-triol (14). The structures of these compounds were established by detailed NMR spectroscopic analysis, as well as by comparison with literature data or with authentic samples.

A simple and low-cost airlift photobioreactor for microalgal mass culture

A simple, low-cost, and efficient airlift photobioreactor for microalgal mass culture was designed and developed. The reactor was made of Plexiglas, and composed of three major parts: outer tube, draft tube and air duct. The fluid-dynamic characteristics of the airlift reactor were studied. The system proved to be well suited to the mass cultivation of a marine microalga, Chlorella sp. In batch culture, the biomass volumetric output rate of 0.21 g l(-1) d(-1) was obtained at the superficial gas velocity of 4 mm s(-1) in the draft tube.

Population genetics of Crassostrea ariakensis in Asia inferred from microsatellite markers

Crassostrea ariakensis is an important aquacultured oyster species in Asia, its native region. During the past decade, consideration was given to introducing C. ariakensis into Chesapeake Bay, in the United States, to help revive the declining native oyster industry and bolster the local ecosystem. Little is known about the ecology and biology of this species in Asia due to confusion with nomenclature and difficulty in accurately identifying the species of wild populations in their natural environment. Even less research has been done on the population genetics of native populations of C. ariakensis in Asia. We examined the magnitude and pattern of genetic differentiation among 10 wild populations of C. ariakensis from its confirmed distribution range using eight polymorphic microsatellite markers. Results showed a small but significant global theta (ST) (0.018), indicating genetic heterogeneity among populations. Eight genetically distinct populations were further distinguished based on population pairwise theta (ST) comparisons, including one in Japan, four in China, and three populations along the coast of South Korea. A significant positive association was detected between genetic and geographic distances among populations, suggesting a genetic pattern of isolation by distance. This research represents a novel observation on wild genetic population structuring in a coastal bivalve species along the coast of the northwest Pacific.

Bottom simulating reflector and gas seepage in Okinawa Trough: Evidence of gas hydrate in an active back-arc basin

To look for gas hydrate, 22 multi-channel and 3 single-channel seismic lines on the East China Sea (ECS) shelf slope and at the bottom of the Okinawa Trough were examined. It was found that there was indeed bottom simulating reflector (BSR) occurrence, but it is very rare. Besides several BSRs, a gas seepage was also found. As shown by the data, both the BSR and gas seepage are all related with local geological structures, such as mud diapir, anticline, and fault-controlled graben-like structure. However, similar structural "anomalies" are quite common in the tectonically very active Okinawa Trough region, but very few of them have developed BSR or gas seepage. The article points out that the main reason is probably the low concentration of organic carbon of the sediment in this area. It was speculated that the rare occurrence of gas hydrates in this region is governed by structure-controlled fluid flow. Numerous faults and fractures form a network of high-permeability channels in the sediment and highly fractured igneous basement to allow fluid circulation and ventilation. Fluid flow in this tectonic environment is driven primarily by thermal buoyancy and takes place on a wide range of spatial scales. The fluid flow may play two roles to facilitate hydrate formation: to help gather enough methane into a small area and to modulate the thermal regime.

海水和海泥中阴极保护系统的边界元计算

随着人们对能源需求的不断增加，深海海洋油气开发已引起了人们越来越大的兴趣，随之而来的是对海洋构筑物的设计和防护提出了更高的要求。由于在传统的阴极保护工程设计中，大多采用实际测量或经验估计的方法来掌握电位分布规律，很难真实的反映构筑物的实际状态，为了确保安全，往往采用较大的安全系数，不但会造成金属材料的浪费，而且还会在构筑物的局部造成保护不足或过保护。 本文研究了边界元方法（BEM）利用数值仿真技术对阴极保护状态下的海洋构筑物的保护状态进行模拟，从而获得阴极保护状态下的金属材料的电位分布。采用常数单元对于二维问题进行了研究，推导出了边界积分方程的离散化形式，并结合阴极保护环境下的阳极和阴极的极化曲线作为边界条件，建立了线性方程组。采用Newton-Raphson 迭代法和分段拟线性化的方法对边界条件做了线性化处理，应用FORTRAN语言开发出阴极保护的边界元仿真求解程序CPBEM，并利用该程序选择合适的算例进行了验证，结果表明该程序是有效和可行的。 通过管线钢在不同温度海泥埋片的腐蚀失重实验，证明了如果有充足的氧的供给的情况下，温度每增加10oC，腐蚀速度便增加一倍。阴极保护系统数值仿真的精确度最主要的影响因素就是阴极和阳极的极化曲线。而金属材料的极化曲线往往受到多种环境因素的影响，本文系统的讨论了在海泥介质中两种管线钢的腐蚀行为，对管线钢极化行为产生影响的各种环境因素，以及这些因素与金属的腐蚀速度之间的关系。首次将灰关联分析的手段运用到海泥介质的腐蚀，研究了环境因素对于ERW，SML两种管线钢在海泥中的腐蚀速率的影响。

Boundary Element Method (BEM) Analysis for Galvanic Corrosion of Hot Dip Galvanized Steel Immersed in Seawater

A numerical analysis of galvanic corrosion of hot-dip galvanized steel immersed in seawater was presented. The analysis was based on the boundary element methods (BEMs) coupled with Newton-Raphson iterative technique to treat the nonlinear boundary conditions, which were determined by the experimental polarization curves. Results showed that galvanic current density concentrates on the boundary of steel substrate and zinc coating, and the sacrificial protection of zinc coating to steel substrate results in overprotection of steel cathode. Not only oxygen reduction but also hydrogen reduction could occur as cathode reactions, which probably led up to the adsorption and absorption of hydrogen atoms. Flat galvanized steel tensile sample shows a brittle behavior similar to hydrogen embrittlement according to the SSRT (show strain rate test) in seawater.

唐古特大黄的粉末X射线衍射图谱

采用粉末X射线衍射法对3个唐古特大黄和1个掌叶大黄样品进行分析,获得了唐古特大黄的特征峰值及标准X射线衍射图谱.

藏药大果大戟中的巨大戟烷型二萜酯类成分

目的研究藏药大果大戟Euphorbia wallichii丙酮提取物中的化学成分。方法用溶剂提取，常规硅胶柱色谱分离和葡聚糖凝胶Sephadex LH-20纯化，采用化学方法和现代波谱分析技术（包括IR，HRESIMS，HRSIMS，1D和2DNMR等）鉴定其化学结构。结果从青海产大果大戟根的丙酮提取物中分离得到6个化合物，分别鉴定为：羊毛甾醇（lanosterol，Ⅰ）、巨大戟二萜-20-肉豆蔻酸酯（ingenol-20-myristinate，Ⅱ）、巨大戟二萜-3-肉豆蔻酸酯（ingenol-3-myristinate，Ⅲ）、没食子酸（gallicacid，Ⅳ）、1-O-a-L-阿拉伯糖-（1→6）-β-D-葡萄糖苷-3，7-二甲基-2-烯-7-羟基-辛醇（1-O-a-L-arabinofuranosyl-（1→6）-β-D-glucopyranosyl-3，7-dimethyl-oct-2-en-7-ol，Ⅴ）、1-O-没食子酰葡萄糖苷（1-O-galloyl-β-D-glucose，Ⅵ）。结论巨大戟烷型二萜酯类化合物Ⅱ和Ⅲ为新化合物，其他化合物均为首次从该植物中分离得到，单萜二糖苷类化合物Ⅴ系首次在该属中发现。