MOCVD of AlGaAs/GaAs with novel group III compounds

The MOCVD of AlGaAs and GaAs from coordinatively saturated group III source materialsi.e. 1–3-dimethyl-aminopropyl-l-galla-cyclohexane ((C₅H₁₀)Ga(C₂N(CH_{3 2}) and the corresponding Al compound) was investigated. It was demonstrated that these precursors, which are inherently free of alkoxy contamination, are suitable for epitaxial growth of GaAs layers and structures of GaAs/AlGaAs. For comparison, data achieved with TEA (Al(C₂H₅)₃) or TⁱBA (Alⁱ(C₄H₉)₃) and TEG (Ga(C₂H₅)₃) are presented. A basic finding of this study is that due to the low thermal stability of TEA, TⁱBA and TEG the layers grown from these compounds suffer from insufficient homogeneity of layer thickness and composition. In contrast, the coordinatively saturated compounds show a reactivity suitable for large area growth. Additionally, intrinsic impurity (N, C) uptake appears to be low and electrical as well as PL data show the satisfactory quality of GaAs and AlGaAs layers grown from this new type of precursors. Specifically, a reduction of oxygen incorporation compared to growth from the standard trialkyls is indicated by PL measurements on layers grown at different temperatures.     

MCM-41纳米粒子的制备

以十六烷基三甲基溴化铵(CTAB)为模板剂,通过添加MCM-41前驱体合成了MCM-41纳米粒子,采用XRD、SEM、FTIR等手段对样品进行了分析表征。结果表明加入MCM-41前驱体合成的固体产物具有MCM-41特有的六方排列的孔道结构和较高的有序度,所合成的MCM-41平均粒径为70 nm。     

前体物质对辅酶Q_(10)生物合成的影响

首次研究了以辅酶Q10 (CoQ10 )主要侧链供给前体物质———茄尼醇和醌环供给前体———羟基苯甲酸和辅酶Q0 对粟酒裂殖酵母(Schizosaccharomycespromb 2 1794 - 2 3) 生产CoQ10 产量的影响,并对前体的转化工艺进行了初步研究。确定了适宜于粟酒裂殖酵母生长及高转化前体生成CoQ10 的条件为:酵母在2 8℃下,2 2 0r/min于发酵培养基中培养18h后,加入0 5 g/L茄尼醇继续发酵培养18h ,进行前体转化反应。结果表明,单独添加茄尼醇能达到最大产量33 1mg/L ,比对照样品增加了91% ,任2种前体物质共同添加都要比单独添加茄尼醇时产量低。茄尼醇和CoQ0 共同添加时,单位细胞胞外辅酶CoQ10 的产量达到最高的1 35mg/g ,比对照样品增加了117%。     

Life cycle optimization of building energy systems

A life cycle optimization model intended to potentially reduce the environmental impacts of energy use in commercial buildings is presented. A combination of energy simulation, life cycle assessment, and operations research techniques are used to develop the model. In addition to conventional energy systems, such as the electric grid and a gas boiler, cogeneration systems which concurrently generate power and heat are investigated as an alternative source of energy. Cogeneration systems appeared to be an attractive alternative to conventional systems when considering life cycle environmental criteria. Internal combustion engine and microturbine (MT) cogeneration systems resulted in a reduction of up to 38% in global warming potential compared with conventional systems, while solid oxide fuel cell and MT cogeneration systems resulted in a reduction of up to 94% in tropospheric ozone precursor potential (TOPP). Results include a Pareto-optimal frontier between reducing costs and reducing the selected environmental indicators.     

The effects of the morphology on the CIGS thin films prepared by CuInGa single precursor

Cu(In_xGa_1−x)Se₂ (CIGS) thin films were prepared by selenization of CuInGa single-layer metallic precursors. At the first stage, CuInGa metallic precursors were deposited onto soda lime glass by direct current (DC) magnetron sputtering system using a CuInGa ternary alloy target with a composition ratio of Cu:In:Ga of 1:0.7:0.3. The precursor films were reacted with Se vapor in vacuum evaporation system. By means of X-ray diffraction (XRD), field emission scanning electron microscope (SEM) and electron probe microanalysis (EPMA), it was found that CIGS thin films exhibit large facetted grains and single chalcopyrite phase with preferred orientation along (1 1 2) plane. Meanwhile, the surface roughness of the CIGS films can be determined by the morphology of the precursor films.     

Hydrolysis of grape monoterpenyl glycosides by Candida molischiana and Candida wickerhamii β-glucosidases

The exocellular β-glucosidases of Candida molischiana and Candida wickerhamii are able to hydrolyse geranyl, neryl, citronellyl, linalyl and α-terpinyl-β-D -glucopyranosides. The nature of the aglycone residue greatly affects the rate of hydrolysis. Glucosides with a tertiary alcohol as aglycone residue are more slowly hydrolysed than those with a primary alcohol. The β-glucosidase from C molischiana is also able to hydrolse α-L-arabinofuranosides. This results in the release of monoterpenols from a glycoside extract from grape juice.     

Kinetics of clusters of elementary damages in loaded materials: Probabilistic cellular automation modeling

A probabilistic cellular automation is used to model accumulation of elementary damages and evolution of their clustering arrangement. Kinetic characteristics of the dynamics of the cluster quantity and evolution of the time correlation functions for the cluster quantity and elementary damage quantity are studied. It is established that their behavior has some features that are possible to interpret as the precursors of transition of the system to the pre-failure stage of evolution. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 1, pp. 49–60, January–February, 2006.