TRANSIENT SCANNING ELECTRON BEAM ANNEALING METHODS USED TO STUDY DIFFUSION AND DEFECTS IN IMPLANTED SILICON.

Rapid thermal annealing of arsenic and boron difluoride implants, such as those used for source/drain regions in CMOS, has been carried out using a scanning electron beam annealer, as part of a study of transient diffusion effects. Three types of e-beam anneal have been performed, with peak temperatures in the range 900 -1200 degree C; the normal isothermal e-beam anneals, together with sub-second fast anneals and 'dual-pulse' anneals, in which the sample undergoes an isothermal pre-anneal followed by rapid heating to the required anneal temperature is less than 0. 5s. The diffusion occuring during these anneal cycles has been modelled using SPS-1D, an implant and diffusion modelling program developed by one of the authors. This has been modified to incorporate simulated temperature vs. time cycles for the anneals. Results are presented applying the usual equilibrium clustering model, a transient point-defect enhancement to the diffusivity proposed recently by Fair and a new dynamic clustering model for arsenic. Good agreement with SIMS measurements is obtained using the dynamic clustering model, without recourse to a transient defect model.

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。

干旱对不同冬小麦旗叶光合产物供应能力的影响

研究干旱对小麦旗叶光合产物供应能力的影响,揭示小麦抗旱高产的生理机制,为提高小麦的抗旱能力及高产稳产提供理论依据。【方法】在防雨池栽培条件下,以旱地冬小麦品种长武134(抗旱性强)和水地冬小麦品种陕253(抗旱性弱)为试材,以适宜水分处理为对照(CK,土壤含水量为田间持水量的70%～75%),研究干旱处理(土壤含水量为田间持水量的50%～55%)对不同冬小麦旗叶光合产物供应速率(净光合速率和蔗糖合成能力)和供应持续期的影响。【结果】与对照相比,干旱处理降低了冬小麦灌浆中后期旗叶净光合速率,缩短了净光合速率高值持续期(PAD),其中长武134降幅较小,净光合速率较高;干旱处理提高了冬小麦灌浆初期旗叶的蔗糖磷酸合成酶(SPS)活性,其中长武134增幅较大,且在灌浆中后期依然能保持相对较高的蔗糖供应能力;干旱处理缩短了冬小麦叶绿素含量缓降期(RSP),提高了丙二醛(MDA)含量,加速了旗叶的衰老,缩短了光合产物的供应持续期,其中长武134受干旱影响较小;干旱处理降低了冬小麦灌浆中后期主茎穗粒质量积累量及其速率,其中长武134降幅较小。【结论】干旱条件下,抗旱品种长武134旗叶在灌浆中后期可维持较高的光合产物...

稀土-聚合物纳米复合材料的制备与表征

纳米材料以其特有的优异性能成为下一代信息技术、能源技术和生物医学技术的重要基础。纳米材料的研究是一个多学科交叉的领域，受到各国科学家及政府的极大重视，成为当前科学研究的热点前沿领域之一。近年来，无机纳米微粒与聚合物复合而成的无机-有机纳米复合材料可能成为集无机、有机、纳米等诸多材料的优良特性于一身的新型功能材料，倍受各国研究者的关注，对无机-有 机纳米复合材料的研究构成了当前纳米材料领域的新热点。我们在当今科学研究的前沿领域内，通过大量文献调研，选择稀土化合物为 目标化合物，开展了研究工作。采用新方法制备了ZnS、ZnS:Eu、ZnS:Mn、ZnS:Mn,Eu和CeO_2纳米微粒，制备了稀土硫化物、CeO_2纳米微粒与聚苯乙烯的纳米复合材料，对所制备的材料进行了表征，研究了反应过程及材料的发光特性，取得了一些创新性结果。1．首次采用固相法在接近室温和室温条件下，分别以硫代乙酰胺(TAA)和硫化钠为原料与醋酸锌进行反应，成功地制备出ZnS纳米微粒，通过XRD、TEM、SPS、荧光光谱等对样品进行了表征，通过差热分析对反应机理进行了研究，得到以下结论：(1)．ZnS纳米微粒具有立方面心结构，为闪锌矿型ZnS。发现TAA与醋酸锌通过低温固相法制备ZnS纳米微粒的最佳温度为100℃，低于此温度反应进行得不完全。提高反应温度将使ZnS纳米微粒的尺寸增大。(2)．100℃下合成的ZnS纳米微粒的晶粒粒径为3.2 nm，TEM观察到的每个ZnS纳米微粒是由更小的ZnS晶粒构成的多晶颗粒，平均颗粒尺寸为40 nm左右。(3)．TAA与醋酸锌反应的历程几乎同时经历了以下几个过程，其中包括TAA的熔融，TAA的分解并产生硫化氢，产生的硫化氢与醋酸锌反应生成醋酸及ZnS，醋酸的气化等，ZnS纳米微粒在上述过程中得以迅速生成，产生的气体物质起到了控制颗粒进一步生长的作用。2．首次采用低温固相法制备出掺杂的ZnS纳米微粒，ZnS:Eu、ZnS:Mn和ZnS:Mn，Eu，研究了制备条件对粒径及发光的影响。研究表明，灼烧温度对掺杂的ZnS纳米微粒的尺寸影响较大，温度升高粒径随之增大：灼烧时间及掺杂浓度对粒径影响很小。荧光光谱中出现了掺杂离子的特征发光，增大掺杂离子浓度及提高灼烧温度可使发光增强。3．首次发现ZnS:Mn纳米粒子经紫外光照射后出现了荧光增强现象。无论是波长为254 nm还是365 nm的紫外光照射后都可以观察到上述现象，并且发现在一定时间范围内，发光亮度随着照射时间的延长而增强。产生这种现象的原因可能是纳米微粒的表面态得到改善，使无辐射通道减少，因而辐射强度提高。4．首次采用表面光电压谱对ZnS纳米微粒进行了表征，观察到表面光电压谱发生了蓝移，ZnS纳米微粒有丰富的表面态。荧光光谱中观察到产生于表面态的陷阱荧光，并发生蓝移。5．采用W/O微乳液法，选用多种非离子型表面活性剂，成功地制备出粒径很小、颗粒均匀的CeO_2纳米晶，对制备过程中的影响因素(如灼烧温度、水与表面活性剂的摩尔比、Ce~(3+)的浓度、灼烧时间、表面活性剂种类等)进行了详细研究。结果如下：(1)．灼烧温度是影响CeO_2纳米微粒尺寸及形貌的关键因素。找到制备纯净的Ce02纳米晶的最佳温度为500℃，低于此温度CeO_2为无定形态，高于此温度则CeO_2纳米微粒的形貌规整但粒径增大。CeO_2纳米微粒的晶格畸变率随着灼烧温度的升高和粒径的增大而减小。(2)．W(水与表面活性剂的摩尔比)、Ce~(3+)浓度、灼烧时间、表面活性剂种类等也对CeO_2纳米微粒的尺寸有影响，但其影响小于灼烧温度的影响。(3)．首次在高分辨条件下通过TEM观察到CeO_2纳米晶的条纹相结构。6．首次将CeO_2纳米微粒与聚苯乙烯复合，成功地制备出CeO_2聚苯乙烯纳米复合材料，对材料进行了表征。(1)．CeO_2/聚苯乙烯纳米复合材料的IR光谱中有Ce-O键的振动吸收，且比通常CeO_2的Ce-O键的振动吸收向高能方向移动，说明CeO_2粒径较小。(2)．XPS谱中Ce的3d_(5/2)和3d_(3/2)结合能较CeO_2的标准谱向高能方向发生了移动，表明CeO_2与表面活性剂及聚苯乙烯之间存在着某种化学键作用。7．首次采用原位合成法制备出稀土硫化物聚苯乙烯纳米复合材料，并通过荧光光谱、磁性、光电子能谱、透射电镜等手段对它们进行了表征。研究了该复合材料的磁性质、荧光光谱、XPS谱、微结构与掺稀土聚苯乙烯相比发生的变化，分析了产生上述变化的原因。(1)．在掺Eu聚苯乙烯复合材料的激发光谱和发射光谱中可见Eu~(3+)的激发和发射峰。Eu~(3+)离子处于对称性很低的聚合物环境中，发射光谱中所出现的~5D_0 → ~7F_J(J = 0，l，2，3，4)跃迁的发射峰中~7F_l和~7F_2等能级解除简并发生了能级劈裂。随着Eu浓度增大，Eu~(3+)离子的发射峰强度增加。(2)．稀土硫化物聚苯乙烯纳米复合材料的发射光谱中在400 nm左右有宽带发射，且经紫外光照射后其发光强度降低，这是由于H_2S与Eu~(3+)发生而生成的不很稳定的Eu~(2+)经紫外光照射后被氧化成更为稳定的Eu~(3+)。(3)．稀土硫化物聚苯乙烯纳米复合材料和掺Eu聚苯乙烯复合材料相比，在荧光光谱、磁性、XPS谱和微结构等方面存在较大的差别。研究表明，在稀土硫化物聚苯乙烯复合材料中有较多的Eu~(3+)离子处于无反演对称性的格位，使得它的发射光谱在615 nm处的发光峰为最强；稀土硫化物聚苯乙烯纳米复合材料的饱和磁化强度较掺Eu聚苯乙烯复合材料的低；稀土硫化物聚苯乙烯纳米复合材料的球粒尺寸明显大于掺Eu聚苯乙烯复合材料的球粒尺寸，远大于纯聚苯乙烯的球粒尺寸。

茂金属间规聚苯乙烯结晶行为和结构性质的研究

间规聚苯乙烯（sPS）作为一种新型的工程塑料，结晶速度快，多晶型问题非常复杂。本工作主要利用多种测试分析手段对sPS的晶体结构，结晶行为进行了较系统的研究。系统地研究了温度与sPS各种晶型生成的对应关系，发现由α'型向α"型转变发生在一较窄的温度区间，有一个随温度突变的过程，并且与α'型晶体相比，α"型晶体的晶胞较小，晶体堆砌更为紧密。根据WAXD理论和多峰分解法，推导出各晶型的结晶度计算公式。依据WAXD衍射分析推知冷结晶温度高于230 ℃时有少量β型晶体生成。利用红外定量分析证实了sPS等温熔体结晶时，随结晶温度的升高，α型晶体成分迅速减少，β型成分急剧增加，晶型转分发生在较窄温度区间内。应用DSC分析采用多种方法系统地研究了sPS的结晶动力学。在等温熔体结晶过程中，温度较低时为二维圆盘状生长，结晶较快，存在二次结晶现象；结晶温度较高时为一维纤维状生长，结晶速度较慢，没有二次结晶发生；结晶温度处在二者中间范围为二维圆盘状和一维纤维状混合生长。同时发现在239 ℃处发生了结晶方式由方式II向方式III的转变，据此计算出sPS各结晶动力学参数，比较折叠链功（q）sPS与iPS非常接近，说明二者分子链刚性相当。在等温冷结晶过程中，没有二次结晶发生，晶体的生长方式不随结晶温度的变化而变化。在非等温熔体结晶过程中，慢速降温二次结晶不出现，降温速率越快，二次结晶出现越早。在非等温冷结晶过程中，升温速率适中才会出现二次结晶。用我们组建立的方法可很好地描述sPS的非等温结晶行为。

亚波长金属光栅的光耦合增强效应及透射局域化的模拟研究

介质层上的亚波长金属光栅产生的表面等离子体(surface plasmons,SPs)可以极大地增强光栅下介质层内的透射光强.增强作用从500 nm延续到近红外区域.在波长610 nm附近有接近110%的增强,在波长700 nm及740nm处也有180%左右的增强.而这个波长范围与薄膜太阳能电池的吸收谱很相近,因此这种结构有望大幅度提高薄膜太阳能电池及不同波长光探测嚣等光电转换器件的光耦合效率.