An all-silicon Raman laser

The possibility of light generation and/or amplification in silicon has attracted a great deal of attention for silicon-based optoelectronic applications owing to the potential for forming inexpensive, monolithic integrated optical components. Because of its indirect bandgap, bulk silicon shows very inefficient band-to-band radiative electron-hole recombination. Light emission in silicon has thus focused on the use of silicon engineered materials such as nanocrystals, Si/SiO2 superlattices, erbium-doped silicon-rich oxides, surface-textured bulk silicon and Si/SiGe quantum cascade structures. Stimulated Raman scattering (SRS) has recently been demonstrated as a mechanism to generate optical gain in planar silicon waveguide structures. In fact, net optical gain in the range 2-11 dB due to SRS has been reported in centimetre-sized silicon waveguides using pulsed pumping. Recently, a lasing experiment involving silicon as the gain medium by way of SRS was reported, where the ring laser cavity was formed by an 8-m-long optical fibre. Here we report the experimental demonstration of Raman lasing in a compact, all-silicon, waveguide cavity on a single silicon chip. This demonstration represents an important step towards producing practical continuous-wave optical amplifiers and lasers that could be integrated with other optoelectronic components onto CMOS-compatible silicon chips.     

Tas1r3, encoding a new candidate taste receptor, is allelic to the sweet responsiveness locus Sac

The ability to taste the sweetness of carbohydrate-rich foodstuffs has a critical role in the nutritional status of humans. Although several components of bitter transduction pathways have been identified, the receptors and other sweet transduction elements remain unknown. The Sac locus in mouse, mapped to the distal end of chromosome 4 (refs. 7-9), is the major determinant of differences between sweet-sensitive and -insensitive strains of mice in their responsiveness to saccharin, sucrose and other sweeteners. To identify the human Sac locus, we searched for candidate genes within a region of approximately one million base pairs of the sequenced human genome syntenous to the region of Sac in mouse. From this search, we identified a likely candidate: T1R3, a previously unknown G protein-coupled receptor (GPCR) and the only GPCR in this region. Mouse Tas1r3 (encoding T1r3) maps to within 20,000 bp of the marker closest to Sac (ref. 9) and, like human TAS1R3, is expressed selectively in taste receptor cells. By comparing the sequence of Tas1r3 from several independently derived strains of mice, we identified a specific polymorphism that assorts between taster and non-taster strains. According to models of its structure, T1r3 from non-tasters is predicted to have an extra amino-terminal glycosylation site that, if used, would interfere with dimerization.     

Effects of C and Mn elements on deformation-enhanced ferrite transformation in low carbon (Mn) steels

Effects of C and Mn contents on the deformation-enhanced ferrite transformation (DEFT) in low carbon (Mn) steels have been investigated by hot compression. The microstructures of 2-4μm ultra-fine equiaxed ferrite grains with minors distributed homogeneously can be obtained by DEFT in all the tested steels. The more pronounced refinement is achieved as the C or Mn content increasing because of the higher-density nucleating sites and lower growth rate. The effectiveness of C on the level of refinement is more obvious than that of Mn.     

苄叉丙酮磺酸钠的合成

合成了丁苄叉丙酮磺酸钠，讨论了影响磺化反应的主要因素，其结构经元素分析，ＩＲ，ＭＳ确证，该合成方法转化率较高，工艺较简单，污染少。     

Optical Fiber Grating Sensor for Force Measurement of Anchor Cable

The development of the sensor suitable for measuring large load stress to the anchor cable becomes an important task in bridge construction and maintenance. Therefore, a new type of optical fiber sensor was developed in the laboratory - optical fiber grating sensor for force measurement of anchor cable （OFBFMAC）. No similar report about this kind of sensor has been found up to now in China and other countries. This sensor is proved to be an effective way of monitoring in processes of anchor cable installation, cable cutting, cable force regulation, etc, with the accurate and repeatable measuring results. Its successful application in the tie bar cable force safety monitoring for Wuhan Qingchuan bridge is a new exploration of optical fiber grating sensing technology in bridge tie bar monitoring system.     

薄膜的场致发光

估计进导带的具体结构，计算了碰撞激发截面，从其六个主要特征中看出过热电子能量的重要性，提出了分层优化方案，对预热，加速，发光层分别优化以提高过热电子能量，并以谱线丰富的Ｅｒ＾３＋离子作为发光材料的激活剂，利用其发光强度的蓝或绿红比定性地表示电子的能量，从发光的亮度、效率、蓝红或绿红比都显著了这一方案的优越性。进一步分析了过热电子的能量分布，倍增发生的区域及其系数，场致发光强度与能级寿命的关系、发光     

Buffer management optimization strategy for satellite ATM

1.INTRODUCTIONIn order tosupport integrated services and provide differ-ent quality of service(QoS)guarantees,asynchronoustransfer mode(ATM)technology is advocated in manymulti media broadbandsatellite systems that are under de-velopment worldwide[1].As the performance of satellitechannelsis muchlessreliablethanthose of terrestrial fiberoptics,satellite systems haveto deal withthis problemonphysical layer andlinklayer.For example,somelinklay-er control(LLC)protocols based on ARQ(autom…     

A DYNAMIC OPTIMAL ADVERTISING MODEL FOR NEW PRODUCTS

Many dynamic optimal control models for advertising make efforts to solve the problem of determining optimal advertising expenditures and other variables of interest over time for a firm or several competing firms,However,after analyzing the extant literature,one can find that few dynamic optimal advertising models available consider the problem within the product diffusion framework.Furthermore,the established models involving product diffusion are inspired by the Bass model,which has been out of date.This paper poses a dynamic optimal advertising model for new products,which considers the product diffusion based on the relative newly developed generalized version of the Bass model.In this paper,the optimal control model is used to derive the optimal advertising expenditure policy,which gives some implications to advertising practice.     

Experimental measurements and theoretical calculations of the atomic structure of materials with subangstrom resolution and picometer precision

Lattice defects are unavoidable structural units in materials and play an important role in determining material properties. Compared with the periodic structure of crystals, the atomic configurations of the lattice defects are determined by the coordinates of a large number of atoms, making it difficult to experimentally investigate them. In computational materials science, multiparameter optimization is also a difficult problem and experimental verification is usually required to determine the possibility of obtaining the structure and properties predicted by cal- culations. Using our recent studies on oxide surfaces as examples, we introduce the method of integrated aberra- tion-corrected electron microscopy and the first-principles calculations to analyze the atomic structure of lattice defects. The atomic configurations of defects were mea- sured using quantitative high-resolution electron micros- copy at subangstrom resolution and picometer precision, and then the electronic structure and dynamic behavior of materials can be studied at the atomic scale using the first- principles calculations. The two methods complement each other and can be combined to increase the understanding of the atomic structure of materials in both the time and space dimensions, which will benefit materials design at the atomic scale.     

Effects of solidifi cation cooling rate on the corrosion resistance of Mg – Zn–Ca alloy

This study was carried out to investigate the effect of solidification cooling rate on the corrosion resistance of an Mg–Zn–Ca alloy developed for biomedical applications. A wedge shaped copper mould was used to obtain different solidification cooling rates. Electrochemical and immersion tests were employed to measure the corrosion resistance of Mg–Zn–Ca alloy. It was found that increasing cooling rate resulted in a significant improvement in the corrosion resistance of the Mg–Zn–Ca alloy. The findings were explained in terms of solidification behaviour in association with the change in solubility of the alloying elements, microstructural homogeneity and refinement and chemical homogeneity as well as the increased cooling rates.