Acylierung von Heterocyclen mit Kohlensäurederivaten. II. Endo- und exo-Carbamoylierung von 2-Amino-benzimidazol-Derivaten mit Isocyanaten. Mechanismus der Acylgruppenwanderung

Acylation of Heterocycles with Carbonic Acid Derivatives. II. Endo and Exo Carbamoylation of 2-Amino-benzimidazole Derivatives with Isocyanates. Mechanism of the Acyl Group Migration 2-Amino-benzimidazoles react with isocyanates with good yields to give 2-amino-1-carbamoyl-aminobenzimidazoles 1 at −30°C and the corresponding 2-carbamoyl isomeres 2 at room temperature, respectively. The isomerization mechanism was studied by crossover experiments and kinetic measurements and has been found to consist of inter- and monomolecular acyl transfer.     

Fuelwood: The “other” renewable energy source for Africa?

In recent years, increasing concerns over rising oil prices, supply shortfalls and the environmental impacts of fossil fuel use have fed growing interest in renewable energy sources for Sub-Saharan Africa. Although traditional biofuels already enjoy widespread popularity, their use has often been actively discouraged due to the lingering influence of “fuelwood crisis” era narratives. In particular, urban fuelwood consumption is frequently portrayed as a cause of environmental degradation leading to energy insecurity among low-income households, especially where the resource is commercialized. Such views have had significant influence among policy makers, often resulting in repressive forestry legislation. In contrast, however, a number of researchers have demonstrated that wood energy dependence is often not a significant cause of deforestation and can provide important livelihood opportunities. This article reassesses urban fuelwood sourcing and its impacts using a recent case study conducted by the authors in Maun, Botswana and results previously reported in the literature. Findings indicate that although harvesting is unregulated, its impacts are significantly mitigated by collectors' strong preferences for source sites with abundant dead wood, low competition and recognized access rights. As well, fuelwood vending is found to provide critical support to rural incomes and a key source of low-cost urban energy. As such, the benefits of fuelwood use and avoidance of negative effects will most effectively be achieved by decentralised management approaches that build on local institutions and understandings of the resource.     

分布式设备远程监控系统研究

针对现有设备远程监控系统不能真正有效地支持分布式网络化生产和管理模式,提出一种基于中间件技术的分布式工业设备远程维护系统,该系统不依赖于具体的硬件和软件平台,设备能方便地加入或退出系统。阐述了系统总体结构和系统安全性设计,重点分析了实现分布式结构的关键技术—查询服务器的4个机制及其实现技术方案,并讨论了系统的总体通讯方案,为分布式设备远程服务系统的实现提供了很好的参考价值。该系统有效地提升了企业关键设备的维护效能,为设备远程监控系统的应用推广奠定了基础。     

Computer simulation of the initial rafting process of a nickel-base single-crystal superalloy

Rafting of the γ/γ′ morphology of nickel-base superalloys is a well-known phenomenon during high-temperature deformation. The initial stages of this type of directional coarsening were modeled two-dimensionally by the method of finite elements (FEs) using an energy-perturbation approach. In addition to the elastic energy density, the effect of the local difference of the hydrostatic stresses in γ and γ′ in combination with the different lattice parameters of the two phases was considered in the calculations as a further driving force. From the results of modeling, the deformation-induced internal stresses and strains were determined and used to evaluate the direction-dependent lattice parameters and lattice misfits of the two phases. The results agree well with experimentally determined values.     

Neue Konstruktionsprinzipien bei Tunnelinnenschalen

New Design Philosophy of Inner Tunnel Linings Examinations are presented aiming at the optimisation of reinforcement and thickness of an inner tunnel lining in order to improve the behaviour at serviceability (SLS) and ultimate limit state (ULS). It is expected that especially an acceleration of the construction progress leads to advantages in competition compared with conventionally reinforced linings. A reduced thickness of a lining out of steel fibre concrete (SFB) or a combination of reinforced concrete and steel fibres (SFvSTB) came out best when being experimentally and theoretically examined. Particularly with regard to the cracking formation at SLS, that rules the design of watertight linings, the slender lining is advantageous compared to a conventionally reinforced one (STB).     

STM investigation of the growth structure of Cu-phthalocyanine films with submolecular resolution

In this study Cu-phthalocyanine (CuPc) films have been investigated by scanning tunneling microscopy to get quantitative insight into the morphology of the films from the micrometer range down to nanometer resolution to see the arrangement of the molecules. The molecules on the surface have been found to be arranged in a slipped stacking order rather than in the expected zig-zag orientation normally found for CuPc crystals. The cystal structure could be identified to be an α-polymorph. The STM image of the individual molecules on the surface is in good agreement with calculations of the charge density of the LUMO for an isolated molecule. A model for the growth of the crystals was derived from this study.     

K-Ar Dating of Authigenic Illites and Its Applications to the Study of Hydrocarbon Charging Histories of Typical Sandstone Reservoirs in Tarim Basin, China

1. Introduction The Tarim basin in China is a large composite superimposed basin, in which the commercial hydrocarbon flows have been discovered at 10 different stratigraphic intervals: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Triassic, Ju…     

支持复杂设备运行的全新服务模式——协同服务

由于复杂设备的高度集成和智能化,现有的工业服务模式已不能满足企业需求.在阐述复杂设备协同服务支持必要性的基础上,分析了协同服务与传统工业服务模式的差别,简要论述了建立协同服务支持的关键技术:复杂设备协同服务的组织形式、协同服务的识别与商业模型构建和设备控制与信息支撑技术,为协同服务支持的进一步研究打下了基础.     

Behavior of (1 1 1) grains during the thermal treatment of copper film studied in situ by electron back-scatter diffraction

An annealed Cu blanket film was investigated in situ at high temperature using electron back-scatter diffraction (EBSD). The primary aim of the experiment was to study the changes in the (1 1 1) texture in the Cu film where the microstructure was already stabilized by previous annealing treatment. Two separate investigations were carried out at the same location of the film for better statistical reliability of data. It was found that the (1 1 1) planes got increasingly inclined to the specimen surface with increasing temperature. Additionally, a change in the strength of {1 1 1}〈1 1 0〉 and {1 1 1}〈1 1 2〉 texture components was observed with increasing temperature. Absence of these phenomena in freestanding Cu film indicates the impact of substrate on the behavior of (1 1 1) grains. The effect of substrate on the peculiar behavior of the (1 1 1) grains has been explained by a model which describes the contribution of both dislocations and diffusion to the observed phenomenon. The tilting of the (1 1 1) grains is discussed with reference to the recently reported Bauschinger effect in the Cu films.     

Transport properties of helium near the liquid-vapor critical point. II. Thermal conductivity of a3He-4He mixture

Measurements of the thermal conductivity are reported for an 80%³He-20%⁴He mixture above the critical point along several isotherms and near-critical isochores, using the same techniques and apparatus described for a study of³He. Using again the assumption that the observed conductivity can be decomposed into a sum of a regular and a singular contribution _reg and _sing, it is shown that along two near-critical isochores, _sing diverges. In particular, along the isochore showing the largest at the phase transition, the divergence is nearly the same as for³He and can be roughly characterized by a simple power law (T-T_c)^– with 0.58. This observation is contrary to predictions that foresee _sing0 asT _c is approached. The relaxation times characterizing the attainment of steady state conditions after switching the heat flux on and off show a similar behaviour as a function of reduced temperature as do those for pure³He. This result might indicate a substantial coupling between concentration and entropy diffusion. In the Appendix, the correlation length for³He nearT _c is calculated from heat conductivity, viscosity, and specific heat data.Work supported by Grant DMR 8024056 of the National Science Foundation.