5-Desazapteridine,synthese und NMR-spektroskopie

A simple synthesis of 28 new 6-alkyl- and 5,6-cycloalkeno-5-deazapteridines, also referred to as pyrido[2′,3′-d]pyrimidines, is described. 4-Aminouracils with various substituents at position 2 and N,N-unsubstituted β-enaminocarbonyl compounds such as 3-aminoacroleins and 2-aminomethylenecycloalkanones are the starting materials. The method is also applied to the preparation of terpenoid 5-deazapteridines from 2-aminomethylene terpene ketones. The fragmentation pattern of these heterocycles in the mass spectra is outlined, and the proton and carbon-13 NMR spectra are discussed.     

Photon channelling in foams

Experiments by Gittings, Bandyopadhyay and Durian (Europhys. Lett. 65, 414 (2004)) demonstrate that light possesses a higher probability to propagate in the liquid phase of a foam due to total reflection. The authors term this observation photon channelling which we investigate in this article theoretically. We first derive a central relation in the work of Gitting et al. without any free parameters. It links the photon's path-length fraction f in the liquid phase to the liquid fraction ɛ. We then construct two-dimensional Voronoi foams, replace the cell edges by channels to represent the liquid films and simulate photon paths according to the laws of ray optics using transmission and reflection coefficients from Fresnel's formulas. In an exact honeycomb foam, the photons show superdiffusive behavior. It becomes diffusive as soon as disorder is introduced into the foams. The dependence of the diffusion constant on channel width and refractive index is explained by a one-dimensional random-walk model. It contains a photon channelling state that is crucial for the understanding of the numerical results. At the end, we shortly comment on the observation that photon channelling only occurs in a finite range of ɛ.     

Laser-induced fluorescence measurement of the ion-energy-distribution function in a collisionless reconnection experiment

Observations in space and laboratory plasmas suggest magnetic reconnection as a mechanism for ion heating and formation of non-Maxwellian ion velocity distribution functions (IVDF). Laser-induced fluorescence measurements of the IVDF parallel to the X line of a periodically driven reconnection experiment are presented. A time-resolved analysis yields the evolution of the IVDF within a reconnection cycle. It is shown that reconnection causes a strong increase of the ion temperature, where the strongest increase is found at the maximum reconnection rate. Monte Carlo simulations demonstrate that ion heating is a consequence of the in-plane electric field that forms around the X line in response to reconnection.     

Evaluation of various fire retardants for use in wood flour-polyethylene composites

Wood-plastic composites represent a growing class of materials used by the residential construction industry and the furniture industry. For some applications in these industries, the fire performance of the material must be known, and in some cases improved. However, the fire performance of wood-plastic composites is not well understood, and there is little information regarding the effectiveness of various fire retardants in the public domain. We used oxygen index and cone calorimeter tests to characterize the fire performance of wood flour-polyethylene composites, and compared the results with unfilled polyethylene and solid wood. We then evaluated the effect of five additive-type fire retardants on fire performance. Generally, magnesium hydroxide and ammonium polyphosphate improved the fire performance of WPCs the most while a bromine-based fire retardant and zinc borate improved fire performance the least.     

POWER7创新微处理器架构从里到外由上至下突破运算效能

由于网络的发达,计算机运算已逐渐从数据中心移至全球网络,今日的信息人员不再思考该如何利用数据中心来管理PC网络或ERP系统,而是考虑该如何让网格（Grid）自我管理。以智能电表为例，透过网络与电表的链接．未来将不再是一个月读表一次，而是每15分钟读表一次．这样的改变．将造成数据量快速地膨胀．需要靠更强大的运算核心才能达成任务。     

Chassis dynamometers

Chassis dynamometers are a valuable tool for evaluating the performance of full vehicles. The basic concept is flexible enough that a very wide range of
wheeled vehcles can be tested. They are routinely used to evaluate drive train performance, full vehicle noise and vibration characteristics and other ve-
hicle parameters. Of course, their use is limited to situations in which complete, running vehicles are available. For situations in which that is not true, four poster and shaker tables can be used. These systems are described in the next article in this series.     

Simulations and Sensitivity Analysis of the Vestibulo-Ocular Reflex

Computer simulations and sensitivity analysis of vestibulo-ocular reflex (VOR) gain and phase were performed. The analyses were used to identify neural structures and anatomic sites capable of producing abnormal VOR gain and phase behaviors reported to exist in blind adults.