Morphological and structural studies of sPS/aPS blends

The morphology and structure of the syndiotactic polystyrene (sPS)/atactic polystyrene (aPS) blends with various compositions have been studied by means of DSC, optical microscopy, SAXS, and WAXD. The results show that aPS is miscible with amorphous region of sPS. There is no macroscopic evidence that aPS forms separated domains in the blends. The decrease in crystallinity of sPS in the blends implies segregation of the aPS to the interfibrillar regions of the spherulites of sPS. The constancy of interlamellar distance and melting points indicates that the fibrillar structural units of sPS is unchanged on addition of aPS to sPS, and the unchanging parameters of the sPS unit cells mean that aPS does not enter the unit cells of sPS.

Surface-Bound Selectin-Ligand Binding Is Regulated By Carrier Diffusion

Two-dimensional (2D) kinetics of receptor-ligand interactions governs cell adhesion in many biological processes. While the dissociation kinetics of receptor-ligand bond is extensively investigated, the association kinetics has much less been quantified. Recently receptor-ligand interactions between two surfaces were investigated using a thermal fluctuation assay upon biomembrane force probe technique (Chen et al. in Biophys J 94:694-701, 2008). The regulating factors on association kinetics, however, are not well characterized. Here we developed an alternative thermal fluctuation assay using optical trap technique, which enables to visualize consecutive binding-unbinding transition and to quantify the impact of microbead diffusion on receptor-ligand binding. Three selectin constructs (sLs, sPs, and PLE) and their ligand P-selectin glycoprotein ligand 1 were used to conduct the measurements. It was indicated that bond formation was reduced by enhancing the diffusivity of selectin-coupled carrier, suggesting that carrier diffusion is crucial to determine receptor-ligand binding. It was also found that 2D forward rate predicted upon first-order kinetics was in the order of sPs > sLs > PLE and bond formation was history-dependent. These results further the understandings in regulating association kinetics of surface-bound receptor-ligand interactions.

A large-area photolithography technique based on surface plasmons leakage modes

An atomic force microscope (AFM) assisted surface plasmons leakage radiation photolithography technique has been numerically demonstrated by using two-dimensional finite-difference time-domain (2D-FDTD) method. With the aid of a metallic AFM tip, particular characteristic of the Kretstchmann configuration to excite surface plasmons (SPs) is utilized to achieve large-area patterns with high spatial resolution and contrast, the photoresist could be exposed with low power laser due to the remarkable local field enhancement at the metal/dielectric interface and the resonant localized SPs modes near the tip. Good tolerance on the film thickness and incident angle has been obtained, which provides a good practicability for experiments. This photolithography technique proposed here can realize large-area, high-resolution, high-contrast, nondestructive, arbitrary-structure fabrication of nanoscale devices. (c) 2007 Elsevier B.V. All rights reserved.

不同葡萄糖/果糖类型桃果实发育期间可溶性糖的变化规律和代谢

以成熟果实中不同葡萄糖/果糖（G/F）类型的6个桃品种（G/F≈1品种：‘冈山白’、‘山一白桃’和‘燕红’;高G/F品种：‘张黄7号’、‘龙246’和‘临白7号’）为试材，采用高效液相色谱法测定果实发育期果实和叶片中可溶性糖含量，并在盛花后74 d或101 d测定了‘冈山白’、‘山一白桃’、‘张黄 7号’和‘龙 246’新梢韧皮部中可溶性糖的含量;测定了果实发育过程中‘山一白桃’和‘临白7号’果实中的可溶性糖和淀粉代谢相关酶的活性。研究成熟果实中不同G/F类型桃果实内G/F差异的部位和时期;分析桃果实内G/F差异的可溶性糖代谢调控机理。 成熟果实中不同G/F类型桃果实中均以蔗糖作为主要碳水化合物积累形式，花后43–85 d蔗糖含量很低，随后持续快速积累直至果实成熟;花后43–85 d山梨醇有升高趋势，在果实成熟前40 d左右迅速降低;葡萄糖和果糖含量在果实发育早期较高，之后逐渐降低;但两类不同G/F桃在整个果实发育过程中G/F值与果实成熟时相似。叶片中贮藏的可溶性糖主要是蔗糖和山梨醇，在果实整个发育期间，G/F≈1品种叶片中G/F约1-3，而高G/F品种叶片中G/F约为2-7。G/F≈1品种‘冈山白’和‘山一白桃’与高G/F品种‘张黄 7号’和‘龙 246’韧皮部中山梨醇占总可溶性糖47-63％，显著高于蔗糖、葡萄糖和果糖的含量，G/F为0.8-0.91，且两类不同G/F桃品种间G/F值不存在显著差异。 成熟果实中G/F≈1类型的‘山一白桃’和高G/F值类型的‘临白7号’整个果实发育过程中，葡萄糖、山梨醇和淀粉的含量在这两个品种间一般没有明显差异;‘山一白桃’果实中的果糖含量显著高于‘临白7号’果实中的果糖;果实最后迅速生长期，‘山一白桃’果实中的蔗糖明显高于‘临白7号’。‘山一白桃’和‘临白7号’果实中的NAD+依赖型山梨醇脱氢酶（NAD+-SDH）活性低，两者有相似的变化趋势，一般无显著差异。‘临白7号’果实中的NADP+依赖型山梨醇脱氢酶（NADP+-SDH）和山梨醇氧化酶（SOX）活性一直高于‘山一白桃’，两者NADP+-SDH和SOX的活性分别在花后93-123 d和花后43-93 d有显著差异。‘临白7号’果实中的果糖激酶（FK）活性一般高于‘山一白桃’。花后43-93 d，‘临白7号’果实中的磷酸蔗糖合成酶（SPS）和蔗糖合成酶（SS）活性一般显著‘山一白桃’。果实最后迅速生长期，蔗糖快速积累，葡萄糖、果糖、山梨醇和淀粉含量迅速降低，同时伴随有SPS和SS活性的迅速升高。在整个果实发育过程中，两个品种果实中的淀粉酶活性较高，其果实中的淀粉含量和淀粉酶活性都有明显的下降趋势。 研究结果表明，整个果实发育过程中桃果实中均存在G/F≈1和高G/F现象，光合产物在韧皮部的运输对桃果实的G/F没有显著的影响，果实中G/F的差异主要由于果实内糖代谢差异所导致。‘临白7号’果实中山梨醇向果糖方向的转化能力与‘山一白桃’一般没有显著差异，由于不同时期较高的NADP+-SDH和SOX活性，使得山梨醇向葡萄糖方向的转化能力明显高于‘山一白桃’，同时，‘临白7号’果实中的FK活性一般高于‘山一白桃’，因此导致‘临白7号’果实中G/F高于‘山一白桃’。

原生动物生物指数的进一步验证及其适用性分析

利用意大利河流TorrenteStirone和Parma的原生动物数据及水质化学数据 ,对作者所建立的原生动物生物指数的适用性进行了验证 ,结果表明 ,所得CPV与化学综合污染指数有显著的相关 ,说明建立的生物指数有广泛的适用性。文中对SPV的使用方法、适用范围、应注意的问题进行了分析和讨论。

Cloning, characterization and promoter analysis of common carp hairy/Enhancer-of-split-related gene, her6

Some members of hairy/Enhancer-of-split-related gene (HES) family have important effects on axial mesoderm segmentation and the establishment and maintenance of the somite fringe. In fishes. the her6 gene, a member of the HES family, is the homologue Of heS1 in mammals and chicken. In this study, the her6 gene and its full-length cDNA from the common carp (Cyprinus carpio) were isolated and characterized. The genomic sequence of common carp her6 is approximately 1.7 kb. with four exons and three introns, and the full-length cDNA of 1314 bp encodes a Putative polypeptide of 271 amino acids. To analyse the promoter sequence of common carp her6. sequences of various lengths upstream from the transcription initiation site of her6 were fused to enhanced green fluorescent. protein gene (eGFP) and introduced into zebrafish embryos by microinjection to generate transgenic embryos. Our results show that the upstream sequence of 500 bp can direct highly efficient and tissue-specific expression of eGFP in zebrafish embryos. whereas a fragment of 200 bp containing the TATA box and a partial suppressor of hairless paired site sequence (SPS) is not sufficient to drive eGFP expression in zebrafish embryos.

Use of the aquatic protozoa to formulate a community biotic index for an urban water system

Protozoan were collected from 16 stations in water system of Changde City (China) using the PFU method. Sampling programs were conduced on a yearly basis, with seasonal frequency at diverse sites in the water system and 488 species of protozoa was identified. At the same time, Water sampling from these stations was conducted and various water chemical parameters, including DO, COD, BOD5, NH3, TP, and Volatile Phenol, were analyzed. The aim of the research was, on one hand, using chemical method to take an investigation to the water pollution status of Changde City; on the other hand, using protozoan to make an evaluation to the water quality. With the chemical water parameters and protozoa data, a biotic index was derived for the investigated region. The species pollution value (SPV) of 469 protozoa species was established, and the community pollution value (CPV) calculated from SPV was used to evaluate water quality. The method of the biotic index was tested and the result showed that CPV calculated from SPV had a close correlation with the degree of water pollution (p < 0.00001). This indicated that the method of the biotic index is reliable. The water quality degrees divided by CPV were suggested. (c) 2004 Elsevier B.V. All rights reserved.

Development of a biotic index using the correlation of protozoan communities with chemical water quality

A method of comparing data on protozoan communities with chemical parameters is presented. Using data from an extensive survey of the River Hanjiang in China, each species of protozoa has been given a species pollution value (SPV) related to its occurrence in waters with different degrees of pollution. A comprehensive chemical index is calculated for each site based on water quality standards for eight chemical parameters. The index is calculated from the relationship between the observed levels of each chemical at a site, compared with the limits of the drinking water quality standards of the People's Republic of China. From the distribution of each species at sites with differing chemical index values, a SPV is calculated. The SPV for each species is obtained by summing the logarithmic value of 10 times the chemical pollution divided by the number of chemical parameters, then divided by the stations where the species occurs. The community pollution value (CPV), which is the average SPVs of all protozoa at a site, is used to evaluate water quality. The CPV has been shown to have a close correlation with the degree of water pollution. It is not necessary for all the protozoa in a sample to have SPVs listed in this paper, provided at least 56% of the protozoa in a sample have an SPV value, the CPV will be applicable.

Application and validation of a new biotic index using data from several water systems

Protozoans of Lake Donghu were collected from five stations using the PFU method. The sampling was conducted for one year and two times a month. The aim of this research was to test the applicability of a new protozoa biotic index, species pollution value (SPV) and community pollution value (CPV), established by the authors using data from the River Hanjiang. Each station's CPV was calculated from the SPV and the correlation analysis between the CPV and the comprehensive chemical index of stations I, II, III showed a significant correlation between them. The pollution status of the five stations was correctly evaluated by the CPV. These results suggested that the biotic index could be applied in water systems other than the River Hanjiang. The SPV of some protozoa species in Lake Donghu, not observed in the River Hanjiang were established. In order to further test the applicability of the biotic index, protozoan and chemistry data from the Rivers Torrente Stirone and Parma of Italy were used. The results showed that the CPV for the two rivers had a close relationship with the chemical water quality, which indicated that the biotic index could be applied in other parts of the world for the monitoring and estimating of water quality. Since the results of testing and verifying the biotic index in some other water systems in China were also satisfactory, this indicated that the biotic index has an extensive suitability for freshwater ecosystems. As long as more than 50% of the species in a sample have a SPV, the CPV calculated from the SPV is reliable for monitoring and evaluating water quality.

Salt tolerance of Microcoleus vaginatus Gom., a cyanobacterium isolated from desert algal crust, was enhanced by exogenous carbohydrates

Microcoleus vaginatus isolated from a desert algal crust of Shapotou was cultured in BG-11 medium containing 0.2mol l(-1) NaCl or 0.2mol l(-1) NaCl plus 100mg l(-1) sucrose, extracellular polymeric substances (EPS) or hot water-soluble polysaccharides (HWP), respectively. Photosynthetic oxygen evolution rates, photosystem 11 activity (Fv/Fm) and dark respiration of NaCl-stressed cells were enhanced significantly by the added sucrose or EPS under salt stress conditions (0.2mol l(-1) NaCl). Compared with cells treated with salt alone, sodium contents in cells reduced significantly; the content of cellular total carbohydrate did not change, and intracellular sucrose, water-soluble sugar increased significantly following the addition of exogenous carbohydrates. Sucrose synthase (SS) activity of NaCl-stressed cells increased following the addition of sucrose, and sucrose phosphate synthase (SPS) activity of NaCl-stressed cells increased following the addition of exogenous sucrose, EPS or HWP compared with cells stressed with NaCl only. The results suggested that the extruded EPS might be re-absorbed by cells of M. vaginatus as carbon source, they could increase salt tolerance of M. vaginatus through the changes of carbohydrate metabolism and the selective uptake of sodium ions. (C) 2003 Elsevier Science Ltd. All rights reserved.

Mechanism on Effect of Surface Plasmons Coupling with InGaN/GaN Quantum Wells: Enhancement and Suppression of Photoluminescence Intensity

The photoluminescence (PL) intensity enhancement and suppression mechanism on surface plasmons (SPs) coupling with InGaN/GaN quantum wells (QWs) have been systematically studied. The SP-QW coupling behaviors in the areas of GaN cap layer coated with silver thin film were compared at different temperatures and excitation powers. It is found that the internal quantum efficiency (IQE) of the light emitting diodes (LEDs) varies with temperature and excitation power, which in turn results in anomalous emission enhancement and suppression tendency related to SP-QW coupling. The observation is explained by the balance between the extraction efficiency of SPs and the IQE of LEDs

Simulation of light coupling enhancement and localization of transmission field via subwavelength metallic gratings

Surface plasmons(SPs) generated in nano metallic gratings on medium layer can greatly enhance the transmission field through the metallic gratings. The enhancement effect is achieved from lambda = 500 nm to near-infrared domain. The enhancement rate is about 110 % at the wavelength of about 6 10 nm and about 180 % at lambda = 700 nm and 740 nm where most kinds of thin film solar cells have a high spectral response. These structures should provide a promising way to increase the coupling efficiency of thin film solar cells and optical detectors of different wavelength response.

The investigations on semi-insulating GaAs by surface photovoltaic spectroscopy

The surface photovoltage (SPV) effect induced by the defect states in semi-insulating (SI) GaAs was studied. The PV response below the band edge was measured at room temperature with a de optical biasing. The spectra were found to be strongly dependent on the surface recombination and were attributed to formation of the carrier concentration gradient near the surface region, showing that SPV is a very sensitive and nondestructive technique for characterizing the surface quality of the SI-GaAs wafers.

一种基于软件过程仿真的软件项目风险管理方法

软件开发是一项高度复杂的活动，涉及到人员、过程、产品、客户等多种因素，这些因素中存在着大量的不确定性，在软件项目中表现为风险。风险能够给软件项目带来严重的危害，造成工程延期、成本超支、软件产品质量低下等各种问题，因此软件项目管理者必须对软件项目风险进行有效的管理。 软件项目风险管理是软件项目管理中不可或缺的重要组成部分，但是在实际的软件项目中，软件项目风险管理却常常被忽略，很多项目管理者凭自己的经验和直觉来管理软件项目风险。造成这种现象的原因除了软件企业的文化因素外，主要是因为软件项目管理者缺少操作层面上有效的风险管理方法和工具。 软件过程仿真能够分析软件过程的动态行为特性，预测软件过程执行的性能，是一种很好的软件项目分析和管理工具。软件过程仿真已经广泛应用于包括风险管理在内的软件项目管理的多个方面。多项研究已经表明软件过程仿真作为一种有效的风险管理方法和工具，能够很好的支持软件项目风险管理过程。 为了指导软件项目管理者使用软件过程仿真进行风险管理，本文提出了一种基于软件过程仿真的软件项目风险管理方法（SPS-RM）。该方法是一种使用软件过程仿真进行软件项目风险管理的通用方法框架，实现了“风险监控风险影响分析风险解决”的风险管理过程，并且为每个风险管理活动都提供了相应的过程仿真模型。SPS-RM方法还包括使用软件过程仿真进行风险管理的通用步骤，以及建立和分析过程仿真模型的一般方法，并为模型、步骤和方法都提供了详细的指导说明。 本文的主要贡献包括： 对软件过程仿真在软件项目风险管理中的应用和研究现状进行了调研。调研的目的是为了获得当前的研究进展，找出目前存在的问题，并指出未来可能的研究方向。调研的结果为本文的研究方向提供了很好的指导，也为本文的具体研究内容提供了良好的理论和实际依据。 提出了一种基于软件过程仿真的软件项目风险管理方法（SPS-RM）。该方法是一个使用软件过程仿真进行软件项目风险管理的通用方法框架，其目的是指导广大的软件项目管理者使用软件过程仿真有效的管理软件项目风险。SPS-RM是本文的核心方法，后面对两个具体风险的研究都是基于该方法进行的。 提出了需求变更风险分析仿真方法（RVSim）。需求变更是一种在软件项目中常见的、对软件项目影响较大的风险。本文基于SPS-RM方法对需求变更风险进行研究，提出了需求变更风险分析仿真方法。该方法以需求的横向和纵向跟踪信息为基础，对需求变更的处理过程进行仿真，能够量化的给出单个需求变更或者一系列需求变更对软件项目的时间和工作量的影响，帮助项目管理者更好的理解和管理需求变更风险。 提出了人员离职风险解决仿真方法（LF-ETRS）。人员离职是软件项目中的另一个重要风险。本文基于SPS-RM方法对人员离职风险进行研究，提出了人员离职风险解决仿真方法。该方法的主要特点是首次在对软件项目中的人员进行建模时同时考虑了人的学习和遗忘行为，因此能够更加准确的预测人员替代所需的时间和成本。另外，该方法还考虑了除人员替代外的其他解决措施，通过对多种解决措施进行建模和仿真，项目管理者可以根据项目的实际情况和仿真结果选择最合适的措施来解决人员离职风险。