东湖沉积物中微生物磷脂的垂向分布

以武汉东湖柱状沉积物为研究对象,利用磷脂法测定了3个采样点各层的微生物量,同时测定了沉积物中各层的pH,简要分析了沉积物中磷脂含量的垂向分布与pH垂向分布的相关性。结果表明:各样点沉积物中磷脂平均含量分别为:1号点59.40nmol/g.dw,2号点为20.56nmol/g.dw,3号点为31.57nmol/g.dw。在沉积物的垂向分布上,微生物量与pH均随着沉积物深度的增加而降低,并且存在很高的相关系数。

湖北省钟祥市南湖水生态环境评价

国家“十五”重大科技专项(2202AA601021); 国家杰出青年科学基金项目(39925007); 中国科学院知识创新工程重要方向项目(KSCX2SW102); 中国科学院水生生物研究所学科前沿课题(2002); 淡水生态与生物技术国家重点实验室课题(2002FB11)项目资助

顶空固相微萃取-气相色谱-质谱测定水中异味化合物

采用顶空固相微萃取-气相色谱/质谱联用测定了水中常见的3种异味化合物,即2-甲基异茨醇、土腥素和β-柠檬醛。研究并讨论了纤维头的类型、盐的种类和浓度、温度、萃取时间、搅拌和解吸时间等因素对异味化合物萃取量的影响。结果表明:在水样中加入30%(W/V)的NaCl溶液,采用65μmPDMS/DVB纤维头,在搅拌的条件下,于60℃顶空萃取40min为异味化合物固相微萃取的最佳条件。在优化的条件下,使异味化合物吸附于纤维涂层后,将其在250℃高温下解吸,再用GC-MS分析。土腥素、β-柠檬醛、2-甲基异茨醇的检出

An organizing center in a planar model of neuronal excitability

This paper studies the excitability properties of a generalized FitzHugh-Nagumo model. The model differs from the classical FitzHugh-Nagumo model in that it accounts for the effect of cooperative gating variables such as activation of calcium currents. Excitability is explored by unfolding a pitchfork bifurcation that is shown to organize five different types of excitability. In addition to the three classical types of neuronal excitability, two novel types are described and distinctly associated to the presence of cooperative variables. © 2012 Society for Industrial and Applied Mathematics.

A comparison of 0°-0° and 45°-45° bridge-seeded, YBCO single grains

A variety of multiseeding techniques have been investigated over the past 20 yr in an attempt to enlarge bulk (RE)BCO superconducting samples fabricated by the top-seeded melt growth (TSMG) process for practical applications. Unfortunately, these studies have failed to establish whether technically useful values of trapped field can be achieved in multiseeded bulk samples. In this work specially designed, 0°-0° and 45°-45° bridge seeds of different lengths have been employed to produce improved alignment of the seeds during the TSMG process. The ability of these bridge-seeded samples to trap magnetic field, which is the key superconducting property for practical applications of bulk (RE)BCO, is compared for the samples seeded using 0°-0° and 45°-45° bridge seeds of different lengths. The grain boundaries produced by these bridge seeds are analyzed in detail, and the similarities and differences between the two bridge-seeding processes are discussed. © 2013 The American Ceramic Society.

Efficient parametric uncertainty analysis within the hybrid Finite Element/Statistical Energy Analysis method

This paper is concerned with the development of efficient algorithms for propagating parametric uncertainty within the context of the hybrid Finite Element/Statistical Energy Analysis (FE/SEA) approach to the analysis of complex vibro-acoustic systems. This approach models the system as a combination of SEA subsystems and FE components; it is assumed that the FE components have fully deterministic properties, while the SEA subsystems have a high degree of randomness. The method has been recently generalised by allowing the FE components to possess parametric uncertainty, leading to two ensembles of uncertainty: a non-parametric one (SEA subsystems) and a parametric one (FE components). The SEA subsystems ensemble is dealt with analytically, while the effect of the additional FE components ensemble can be dealt with by Monte Carlo Simulations. However, this approach can be computationally intensive when applied to complex engineering systems having many uncertain parameters. Two different strategies are proposed: (i) the combination of the hybrid FE/SEA method with the First Order Reliability Method which allows the probability of the non-parametric ensemble average of a response variable exceeding a barrier to be calculated and (ii) the combination of the hybrid FE/SEA method with Laplace's method which allows the evaluation of the probability of a response variable exceeding a limit value. The proposed approaches are illustrated using two built-up plate systems with uncertain properties and the results are validated against direct integration, Monte Carlo simulations of the FE and of the hybrid FE/SEA models. © 2013 Elsevier Ltd.

桌面虚拟现实环境下的双手交互技术

面向桌面虚拟环境,在分析通用交互设备特点的基础上,提出了具有广泛适用性的双手交互的设备组合;根据虚拟现实通用交互任务的需求,结合设备特点,提出了为左、右手设备分配不同的子任务的策略;组合不同的单手交互技术,提出了包括基于辅助平面的双手交互等3个适用于典型桌面设备组合的双手交互技术;开发了双手交互技术工具箱,并进行了应用验证·

南海北部白云凹陷08CF7岩心沉积物的磁化率特征及其意义

以汕头市六区一县为研究区域，采用1996—2007年土地利用详查变更数据，分析

海底沉积物声衰减同轴差距衰减测量法与其他测量方法的对比研究

以精度较高的现场测量Hamilton的原位测量所得数据为标准，对比研究了钱正明的直立同轴衰减测量法、刘强

ZnO单晶的缺陷及其对材料性质的影响

利用X射线衍射技术、荧光光谱、霍尔效应和光学显微等方法分别研究了ZnO单晶的品格完整性、深能级缺陷、电学性质、位错和生长极性．通过比较ZnO单晶材料在退火前后的测试结果，分析了材料的缺陷属性和缺陷对材料性质、晶体完整性的影响．

High-Integrated-Photosensitivity Negative-Electron-Affinity GaAs Photocathodes with Multilayer Be-Doping Structures

The effect of changing Be doping concentration in GaAs layer on the integrated photosensitivity for nega- tive-electron-affinity GaAs photocathodes is investigated. Two GaAs samples with the monolayer structure and the muhilayer structure are grown by molecular beam epitaxy. The former has a constant Be concentration of 1 × 10^19 cm^-3, while the latter includes four layers with Be doping concentrations of 1 × 10^19, 7 × 10^18, 4 × 10^18, and 1 × 10^18 cm^-3 from the bottom to the surface. Negative-electron-affinity GaAs photocathodes are fabricated by exciting the sample surfaces with alternating input of Cs and O in the high vacuum system. The spectral response results measured by the on-line spectral response measurement system show that the integrated photosensitivity of the photocathode with the muhilayer structure enhanced by at least 50% as compared to that of the monolayer structure. This attributes to the improvement in the crystal quality and the increase in the surface escape probability. Different stress situations are observed on GaAs samples with monolayer structure and muhilayer structure, respectively.

非原生掺杂半绝缘磷化铟（InP）及其应用对比

过去的几年中，由于1.31和1.55μm波长半导体激光器在光纤通信领域得到了广泛的应用，磷化铟（InP）衬底材料的研究和规模化生产因此受到了极大的推动，并已逐步成为继硅（Si）和砷化镓（GaAs）之后又一重要的化合物半导体材料。与GaAs相比，InP晶体具有高的饱和电场漂移速度、良好的导热性和较强的抗辐射能力等优点，因此更适合于制造高频、高速、大功率及外层空间用微波器件和电路。从实际使用的情况看，n和p型InP衬底的性能已基本满足要求，而半绝缘类型衬底则无论从一致性还是均匀性方面都需要较大程度地改善。相应地，这种改善的途径和方法已成为半导体材料的研究热点之一。