Current Status on Stem Cells and Cancers of the Gastric Epithelium

Gastric cancer is still a leading cause of cancer-related mortality worldwide in spite of declining incidence. Gastric cancers are, essentially, adenocarcinomas and one of the strongest risk factors is still infection with Helicobacter pylori. Within the last years, it became clear that gastric self-renewal and carcinogenesis are intimately linked, particularly during chronic inflammatory conditions. Generally, gastric cancer is now regarded as a disease resulting from dysregulated differentiation of stem and progenitor cells, mainly due to an inflammatory environment. However, the situation in the stomach is rather complex, consisting of two types of gastric units which show bidirectional self-renewal from an unexpectedly large variety of progenitor/stem cell populations. As in many other tumors, cancer stem cells have also been characterized for gastric cancer. This review focuses on the various gastric epithelial stem cells, how they contribute to self-renewal and which routes are known to gastric adenocarcinomas, including their stem cells.     

SPEM2XPDL模型转换研究*

将软件过程技术与工作流技术相结合,严格定义了SPEM2XPDL模型转换规则,设计并实现了一个SPEM2XPDL模型转换引擎.此引擎将SPEM描述的软件过程转换为符合工作流定义(XPDL)的工作流过程,从而可基于工作流管理系统对软件过程提供执行支持.SPEM模型经引擎转换后在工作流管理系统Shark上的成功执行表明了引擎的可用性.     

基于SPEM2XPDL模型转换的软件过程执行

SPEM(software process engineering metamodel)是国际标准化组织制定的标准元模型,正日益成为软件过程建模领域的行业标准,但在过程执行方面,SPEM还存在不足.将软件过程看作是一种特殊的工作流,提出了一种应用工作流运行机制支持软件过程执行的方法.通过将SPEM模型转换为XPDL(XML process definition language)模型,利用XPDL引擎支持SPEM模型的执行.制定了SPEM和XPDL之间的映射规则,设计了转换算法并开发了转换引擎.该方法被应用在SoftPM项目中,成功地基于XPDL引擎Shark实现了对软件过程模型的执行支持.     

Study of a proton exchange membrane fuel cells catalyst subjected to anodic operating conditions, by synchrotron-based scanning photoelectron microscopy (SPEM) and high lateral-resolution X-ray photoelectron spectroscopy

In this paper we report an investigation of the degradation of the Pt/C electrocatalyst of an anodic membrane-electrode assembly (MEA) after 1000 h of operation in a laboratory single-cell PEMFC, using synchrotron-based space-resolved photoelectron spectroscopy. This study is complemented by the analysis of a pristine MEA and reference materials, as well as by electrochemical measurements, SEM imaging and energy-dispersive X-ray fluorescence spectroscopy (EDX). Catalyst ageing correlates with a corrugation of morphology, as observed by SEM and scanning photoelectron microscopy (SPEM), corresponding to Pt nanoparticle agglomeration. Moreover - on the basis of high lateral resolution SPEM, X-ray photoelectron spectroscopy (XPS) and EDX analyses, - we found that, after operation, Pt is transported onto the fibres of the gas-diffusion layer (GDL). Space-resolved XPS shows a peak shift of the Pt 4f_7/2 level to higher and lower binding energies with respect to Pt(1 1 1) and pristine Pt black, respectively, corresponding to nanocrystallinity in the first case and agglomeration in the second one. No oxidised Pt was found in any location of the anodically used MEA.     

基于SPEM扩展元模型的PSP实施方法*

提出了一种支持PSP过程的SPEM扩展元模型P-SPEM,并给出了基于P-SPEM的PSP实施过程及支持该过程的原型工具.其中使用PROBE方法帮助个体进行项目计划和估算,用DEA分析方法综合评价工程师的过程性能,有效地指导工程师实施PSP.     

Chemically resolved dynamical imaging of catalytic reactions on composite surfaces

The catalytic reduction of NO by hydrogen is investigated at (T = 650 K and (p≈10^-6 mbar on a microstructured Rh/Pt(100) surface consisting of Pt(100) domains surrounded by a 600 Åthick Rh film. Synchrotron radiation scanning photoemission microscopy (SPEM), using photons focused into a spot of less than 0.2 μm diameter, is employed as a spatially and chemically resolving in situ technique. The chemical waves which arise in the bistable system NO+H₂/Rh are imaged with SPEM monitoring the N 1s and O 1s photoelectrons. The reaction fronts initiate transitions from an inactive oxygen-covered surface (Θ_O≈0.25 ML) to a reactive nitrogen-covered surface (Θ_N≈0.06 ML). At the Pt/Rh interface, synergetic effects can be observed: the chemical waves on the Rh film nucleate preferentially at the Pt/Rh interface. This nucleation is poisoned by carbon contamination on the Pt area but is prevented in the vicinity of the Pt/Rh interface by the adjacent clean Rh film. No segregation of Pt to the surface was observed for the 600 Å thick Rh film.     

工作流元模型到SPEM的扩展与映射

为了提高软件开发效率、实现软件过程管理规范化,将工作流技术应用于软件开发过程,实现软件过程自动化管理。软件过程工程元模型(SPEM)是软件过程建模的基础,是一种通用的框架,适合不同类型的生命周期模型。根据软件过程的特点,扩展了工作流元模型,制定了SPEM和工作流元模型之间的映射规则,实现了这两种元模型之间的映射,以瀑布模型为例验证了具有软件过程特点的工作流元模型的有效性。通过工作流引擎解析映射后的工作流元模型,实现软件过程的自动化管理。     

面向对象的软件过程SPEM模型的地位与作用

软件过程是为了构建或者增强一个软件系统而定义的一系列步骤,高质量的软件过程可以帮助开发团队成功地完成开发工作.为了更有效地提高软件过程的质量,人们从各种角度为软件过程建模,利用各种过程模型来规划、定义、建立和实施软件过程.本文介绍了一种面向对象的软件过程SPEM模型,详细分析了它的地位和作用,并通过实例直观地展现了一个SPEM模型.     

An improved smoothed particle electromagnetics method in 3D time domain simulations

In this paper, an enhanced variant of the meshless smoothed particle electromagnetics (SPEM) method is performed in order to solve PDEs in time domain describing 3D transient electromagnetic phenomena. The method appears to be very efficient in approximating spatial derivatives in the numerical treatment of Maxwell's curl equations. In many cases, very often, accuracy degradation, due to a lack of particle consistency, severely limits the usefulness of this approach. A numerical corrective strategy, which allows to restore the SPEM consistency, without any modification of the smoothing kernel function and its derivatives, is presented. The method allows to restore the same order of consistency for both interior and the boundary regions outperforming the original version of SPEM as far as accuracy and stability are concerned. Therefore, computational details are reported and simulations, using uniform and non‐uniform particles distribution in 3D domains, are performed for the first time in order to validate the proposed approach. Copyright © 2011 John Wiley & Sons, Ltd.     

C68: A non-IPR fullerene capable of binding extraordinary amounts of Cs atoms

The non-IPR fulleride compound Cs_xC₆₈ was investigated in analogy to previous experiments on Cs_xC₅₈. While the vibrational properties as well as the electronic structure in the valence band range appear to be pretty similar to Cs_xC₅₈, a striking difference could be observed by XPS and Photoemission Microscopy analysis: apparently, C₆₈ forms different phases within a thick film including islands in which it is able to store more than 70 Cs atoms per fullerene cage and to keep these amounts even after annealing over 1100 K. This means that Cs_xC₆₈ constitutes the highest alkali metal doping degree of any Fullerene species known so far. Spatially resolved photoemission analysis also revealed that the Cs-rich fulleride phases constitute a unique chemical state that has never been observed before.