Surface treatmet of sillimanite-based microspheres for strength enhancement of high-temperature lightweight cement composites

The compressive strength of high-temperature lightweight cementing materials containing sillimanite-based hollow microspheres as a filler can be improved by treating the surfaces of the microspheres with a calcium hydroxide-saturated solution at temperatures up to 200° C. The precipitation of an epitaxial layer formed by an interaction between the hot calcium hydroxide solution end the surface of the sphere played an essential role in developing favourable bonding characteristics at the interfaces and in promoting the hydration of the cement matrix. Bonding is associated with the formation of an intermediate layer of aluminium-rich calcium silicate hydrate, produced by an interfacial reaction of the cement paste with the epitaxy under the hydrothermal environment at 300° C. A dense intermediate layer consisting of a rim structure of 4m thickness acts in cross-linking and coupling functions that serve to connect the cement matrix and spheres, thereby improving the interfacial bond strength. The presence of the epitaxial layer on the treated sphere surfaces leads to the formation of a well-crystallized tobermorite matrix phase, which is responsible for the development of strength in autoclaved lightweight cements.     

微软未来的概念操作系统——Singularity

每一个操作系统都是一系列的设计理念的体现，这些设计上的选择包括语言的选择、程序保护的方式、安全模式、系统抽象等。现代操作系统，包括Windows、Linux、Mac OS X以及BSD在设计理念上都有许多共通之处，这种共性并非偶然。究其根原，是因为上述操作系统都是基于二十世纪六十年代到七十年代所形成的操作系统结构理论和开发工具完成的。在这样的前提之下，操作系统的设计者们采用几乎类似的设计理念完成相近的设计，是完全可以预料的结果。     

Generating super stimulated-echoes in MRI and their application to hyperpolarized C-13 diffusion metabolic imaging

Stimulated-echoes in MR can be used to provide high sensitivity to motion and flow, creating diffusion and perfusion weighting as well as T(1) contrast, but conventional approaches inherently suffer from a 50% signal loss. The super stimulated-echo, which uses a specialized radio-frequency (RF) pulse train, has been proposed in order to improve the signal while preserving motion and T(1) sensitivity. This paper presents a novel and straightforward method for designing the super stimulated-echo pulse train using inversion pulse design techniques. This method can also create adiabatic designs with an improved response to RF transmit field variations. The scheme was validated in phantom experiments and shown in vivo to improve signal-to-noise ratio (SNR). We have applied a super stimulated-echo to metabolic MRI with hyperpolarized (13)C-labeled molecules. For spectroscopic imaging of hyperpolarized agents, several repetition times are required but only a single stimulated-echo encoding is feasible, which can lead to unwanted motion blurring. To address this, a super stimulated-echo preparation scheme was used in which the diffusion weighting is terminated prior to the acquisition, and we observed a SNR increases of 60% in phantoms and 49% in vivo over a conventional stimulated-echo. Experiments following injection of hyperpolarized [1-(13)C] -pyruvate in murine transgenic cancer models have shown improved delineation for tumors since signals from metabolites within tumor tissues are retained while those from the vasculature are suppressed by the diffusion preparation scheme.     

Silver-based intermetallic heterostructures in Sb2Te3 thick films with enhanced thermoelectric power factors

In this work, Ag(x)Te(y)-Sb(2)Te(3) heterostructured films are prepared by ligand exchange using hydrazine soluble metal chalcogenide. Because of the created interfacial barrier, cold carriers are more strongly scattered than hot ones and thereby an over 50% enhanced thermoelectric power factor (~2 μW/(cm·K(2))) is obtained at 150 °C. This shows the possibility of engineering multiphases to further improve thermoelectric performance beyond phonon scattering through a low-temperature solution processed route.     

The history of solid-solution-strengthened Ni alloys for aqueous corrosion service

While nickel has been known for centuries as a material for various uses, including the Ni-Fe expansion alloys that were developed around 1896, the history of the solid-solution-strengthened nickel-based alloys begins with the development of the Ni-Cualloy Monel^® in 1996. Since that time many other alloys have been developed containing other elements and possessing significantly different corrosion resistance. These developments have also been aided by developments in the metallurgical processing of nickel alloys. This paper will discuss the major nickel alloy developments that have allowed and expanded the use of these alloys in the chemical processing industry.