Luminescent chemically-etched porous poly-crystalline silicon on insulating substrates

Polycrystalline silicon deposited on insulating substrates has been chemically-etched to form thin films of porous material exhibiting room temperature visible photoluminescence with emission wavelengths of around 650 nm. Material of 4000 ? thickness was quickly converted to porous silicon within 15 s of etching, with an etch rate of 1–1.5 μm/h. In contrast to anodization, chemical-etching parameters have little effect on modulating the resultant peak wavelength. Peak photoluminescence intensity was achieved 8–12 s of etching in 1:3:5 parts HF:HNO₃:H₂O at room temperature with ambient lighting. The chemical etching process and its etch characteristics have been discussed in relation to its suitability for large area thin film devices.     

Innovative wick design for multi-source, flat plate heat pipes

We present a novel micro-heat pipe wick design and fabrication technique to significantly boost the effective thermal conductivity of the heat pipe relative to the monolithic substrate material. Extensive porous flow modeling of the process has provided critical information on the key parameters and the resulting anisotropic wick designs have shown robust performance improvements. A methanol charged copper device reported in this paper showed a maximum thermal conductivity of 760 W/m K prior to dry out. This represents a 1.9× increase over the conductivity of solid copper.     

Porous silicon as an intermediate layer for thin-film solar cell

The potential of porous silicon (PS) with dual porosity structure as an intermediate layer for ultra-thin film solar cells is described. It is shown that a double-layered PS with a porosity of % allows to grow epitaxial Si film at medium temperature (725°–800°C) and at the same time serves as a gettering/diffusion barrier for impurities from potentially contaminated low-cost substrate. A 3.5 μm thin-film cell with reasonable efficiency is realized using such a PS intermediate layer.     

Fabrication of porous bioactive glass particles by one step sintering

In this study, we reported a facile method to prepare porous bioactive glass microparticles. Porous particles were synthesized by sintering hollow bioactive glass microspheres obtained using a sol-gel co-template technology. The results showed that porous bioactive glass particles possessed a narrow particle size distribution, a relatively porous surface morphology and a hollow structure. It is worth to say that the resulting microparticles present an amorphous structure although the sintering temperature was improved compared to hollow microspheres. The presence of macropore on the shell may provide an efficient method to carry drugs in the hollow cores. Considering the high deposit rate of nanoscale apatite for bioactive glass materials, the porous microparticles should have potential applications in drug and bioactive molecules delivery, in addition to bone tissue regeneration.     

比较不同来源钙剂对大鼠骨密度的影响

目的:研究纳米碳酸钙、微晶体羟磷灰钙、乳钙对大鼠骨密度和钙表观吸收率的影响。方法:SPF级4周龄雌性SD大鼠90只,随机分为9组,即纳米碳酸钙、微晶体羟磷灰钙、乳钙低、高剂量组和相应剂量碳酸钙对照组(低、高剂量组饲料钙含量分别为500mg/100g和1000mg/100g),以及低钙对照组(饲料钙含量为150mg/100g)。喂养13周,测钙表观吸收率、骨钙含量和骨密度。结果:不同钙剂组大鼠骨密度均明显高于低钙对照组(P0.05);不同钙剂低剂量组大鼠钙表观吸收率介于52.96%～68.16%之间,高剂量组吸收率介于41.78%～61.30%,均明显低于低钙对照组(P0.05)。结论:与低钙对照组相比,纳米碳酸钙、微晶体羟磷灰钙、乳钙均可明显改善大鼠的骨密度。     

Microwave puffing: Determination of optimal conditions using a coupled multiphase porous media - Large deformation model

Increased interest in microwave puffing is due to its ability to obtain low-fat and ready-to-eat healthy products. Determination of optimal conditions for this complex process has been difficult and although several patents exist on the concept, we are yet to see any large scale commercial use. A fundamental physics based modeling approach integrated with relevant experimentation, developed in this work, is an ideal framework to understand and optimize microwave puffing. The results showed that puffing may not be successful unless carried out using an intensive heating source such as microwaves. Addition of infrared and hot air leads to better quality product whereas using forced air convection is not desirable. There is an optimum initial moisture content depending on the puffing conditions. The study provides critical guidelines to food product/process developers for successful development, control and automation of microwave puffing, thereby leading to value-added nutritious products.