Quantitative off-axis electron holography of GaAs p-n junctions prepared by focused ion beam milling

Focused Ion beam (FIB) prepared GaAs p-n junctions have been examined using off-axis electron holography. Initial analysis of the holograms reveals an experimentally determined built-in potential in the junctions that is significantly smaller than predicted from theory. In this paper we show that through combinations of in situ annealing and in situ biasing of the specimens, by varying the intensity of the incident electron beam, and by modifying the FIB operating parameters, we can develop an improved understanding of phenomena such as the electrically 'inactive' thickness and subsequently recover the predicted value of the built-in potential of the junctions.
PACS numbers: 85.30.De     

数据挖掘在CRM中的应用设计

讨论了在客户关系管理 (CRM)中用于客户细分和建立客户轮廓的数据挖掘技术。首先指出 CRM的概念和分类 ,然后分析了几种数据挖掘方法 ,最后提出面向 CRM的数据挖掘应用设计。     

Single cell-based analysis of torenia petal pigments by a combination of ArF excimer laser micro sampling and nano-high performance liquid chromatography (HPLC)-mass spectrometry

The molecular constituents of the petal pigments of the Torenia plant (Torenia hybrida) were analyzed on a single-cell basis by a combination of newly developed laser-microsampling and nano-flow liquid chromatography-electro spray ionization mass spectrometry (LC-ESIMS) techniques. Our method should provide a facile method for obtaining precise metabolic profiles of each cell in a single plant tissue.     

Involvement of yeast YOL151W/GRE2 in ergosterol metabolism

The Saccharomyces cerevisiae gene YOL151W/GRE2 is widely used as a model gene in studies on yeast regulatory responses to osmotic and oxidative stress. Nevertheless, information concerning the physiological role of this enzyme, a distant homologue of mammalian 3-beta-hydroxysteroid dehydrogenases, is scarce. Combining quantitative phenotypic profiling and protein expression analysis studies, we here report the involvement of yeast Gre2p in ergosterol metabolism. Growth was significantly and exclusively reduced in gre2Delta strains subjected to environmental stress straining the cell membrane. Furthermore, whereas no compensatory mechanisms were activated due to loss of Gre2p during growth in favourable conditions (synthetic defined media, no stress), a striking and highly specific induction of the ergosterol biosynthesis pathway, represented by the enzymes Erg10p, Erg19p and Erg6p, was observed in gre2Delta during growth in a stress condition in which lack of Gre2p significantly affects growth. Involvement of Gre2p in ergosterol metabolism was confirmed by application of an array of selective inhibitors of lipid biosynthesis, as gre2Delta displayed vastly impaired tolerance exclusively to agents targeting the ergosterol biosynthesis. The approach outlined here, combining broad-spectrum phenotypic profiling, expression analysis during conditions reducing the growth of the mutant and functional confirmation by application of highly selective inhibitors, may prove a valuable tool in gene functional analysis.     

Incorporation of oxygen during oxidative annealing of thermally evaporated In films

The paper describes studies on compositional, morphological and optical characteristics of thin indium oxide films prepared by annealing thermally evaporated indium metal films in 423-723 K temperature range in air. The incorporation of oxygen in the films has been probed by depth profiling oxygen using ¹⁸O(p, α)¹⁵N nuclear reaction and 3.05 MeV ¹⁶O(α, α)¹⁶O resonant scattering. The morphology of the films has been examined by atomic force microscopy while their structure by glancing incidence X-ray diffraction. As grown In films are polycrystalline and consist of well-aligned (In) hillocks. The hillocks in thin films (∼12 nm) are nanosized and conical in shape while those in thicker films (∼130 nm) are micron-sized with rather flat tops. Nanosized hillocks impart films enhanced reactivity towards oxygen. Consequently thinner films contain high amount of adsorbed oxygen in as-deposited state and undergo facile oxidation. The hillocks are obliterated in the process. The enhanced reactivity is attributed to high surface energy, generally associated with nanoparticles, and residual stress. These films exhibit high transmission (>90%) on annealing beyond 473 K. Micro-sized hillocks, on the other hand lend pronounced roughness to the films. Roughness and lower surface free energy which manifests in the form of flatter hillock tops, make the films oxidation-resistant. Depth profile measurements in thicker films show that oxidation starts at the surface and proceeds into the interiors of the film with increase in the duration of annealing. The films are deficient in oxygen, even as X-ray diffraction shows the formation of polycrystalline indium oxide. These have low transmission (<30%) and their band gaps increase with the temperature and duration of annealing. The increase in band gap is attributed to the gradual oxidation of interior regions that are initially significantly deficient in oxygen and improvement in crystallinity.     

基于LC-MS/MS的酸乳肽谱及ACE抑制活性

利用液相色谱-串联质谱(liquid chromatography-tandem mass spectrometry,LC-MS/MS)的方法,对4种酸乳(优味舒风味发酵乳、风味发酵乳、初乳24+K风味发酵乳和十天风味发酵乳)的肽谱进行分析,分别鉴定到152、125、364条和274条肽段。利用血管紧张素转换酶(angiotensin converting enzyme,ACE)的抑制活性比较以上4种酸乳的生物活性,在相同质量浓度2.0 mg/L时,4种酸乳ACE抑制率分别为46.84%、42.75%、77.41%和63.84%。初乳24+K风味发酵乳含有肽的数量大、ACE抑制活性高可能与其独特的原料成分相关。对4种酸乳的肽谱及ACE抑制活性的考察,为进一步研究酸乳肽的功能特点和ACE抑制活性提供了理论依据。     

中子深度分析技术的反演迭代计算

针对中子深度剖面分析(NDP),采用蒙特卡罗模拟和概率迭代反演方法计算了硼在硅基底样品内的深度分布。结合CARR堆NDP实验装置,利用MCNP和Geant4软件模拟了标准样品SRM2137中硼元素的能谱图,通过MATLAB软件反演迭代推算解析出了标准样品中元素对应的浓度深度变化图。经验证,反演迭代计算方法适用于NDP系统。     

基于流程剖面的弹性工作流系统设计与实现

工作流技术在办公自动化系统内得到了广泛的应用,却面临业务流程的多样性和易变性等应用难点。针对这一问题,发现办公自动化系统中的流程多样性和易变性的主要原因在于不同人员、不同部门之间的协作,而不是单个流程环节的变化。基于此,所研发的弹性工作流系统首先依据部门职能细粒度的区分与定义部门的原子职能、定义并实现与原子职能匹配的、不可再分的原子业务,形成流程剖面。业务流程的新建和更改等则依据流程剖面,将业务流程实现为原子业务的组合与拼接,支持原子业务之间的任意组合,并以此来满足部门间协作等带来的业务流程易变性等需求。该系统既保留了柔性工作流引擎的多变性,同时也具有传统刚性工作流引擎易用性的特点。