新产品——钢带增强聚乙烯螺旋波纹管

钢带增强聚乙烯螺旋波纹管是一种创新的埋地排水管,把钢材的高刚度、高强度和聚乙烯的柔韧、耐腐结合在一起,突出的优点是环刚度高和节约原材料.     

Significance of fluid regime in biological filtration

A dispersed flow model previously developed to study substrate utilization in unsaturated media was experimentally verified and its practical application was considered. For this purpose, measurements were made using tap water and a synthetic feed solution. The importance of the change in fluid regime as regards to the simultaneous transport and reaction within biological filters were demonstrated. The effect of drop formation and the breakage of liquid jets inside the filters on substrate utilization was also shown.     

材质对蜂窝纸板缓冲性能的影响

对两种不同材质的蜂窝纸板静态应力应变性能和动态缓冲结果进行了比较分析。讨论了蜂窝纸板力学性能对应变速度的敏感性及两种纸板的缓冲性能差异。缓冲试验结果表明。在不同的冲击应变率下蜂窝纸板的材质影响蜂窝纸板缓冲性能。     

Growth and characterization of GaAs films deposited on Ge/Si composite substrates by metalorganic chemical vapor deposition

We report the results of studies which have been made on heteroepitaxial layers of GaAs and AlGaAs grown by metalorganic chemical vapor deposition on composite substrates that consist of four different types of heteroepitaxial layered structures of Ge and Ge-Si grown by molecular beam epitaxy on (100)-oriented Si substrates. It is found that of the four structures studied, the preferred composite substrate is a single layer of Ge ∼1 μm thick grown directly on a Si buffer layer. The double-crystal X-ray rocking curves of 2 μm thick GaAs films grown on such substrates have FWHM values as small as 168 arc sec. Transmission electron micrographs of these Ge/Si composite substrates has shown that the number of dislocations in the Ge heteroepitaxial layer can be greatly reduced by an anneal at about 750° C for 30 min which is simultaneously carried out during the growth of the GaAs layer. The quality of the GaAs layers grown on these composite substrates can be greatly improved by the use of a five-period GaAs-GaAsP strained-layer superlattice (SLS). Using the results of these studies, low-threshold optically pumped AlGaAs-GaAs DH laser structures have been grown by MOCVD on MBE Ge/Si composite substrates.     

Development of High Thermal Conductivity Aluminum Nitride Ceramic

AIN ceramics with densities varying from 3.18 to 3.30 g/cm³ and room-temperature thermal conductivities varying from 88 to 193 W/m K were produced. Different sintering conditions, packing powders, AIN powder sources, carbon additive, and sintering times were evaluated, and the key processing parameters which cause the differences in density and thermal conductivity were identified. SEM, TEM, and EDS were used to characterize the correlation between thermal conductivity, microstructure, and processing parameters. The important parameters which control the thermal conductivity of AIN ceramics are discussed.     

关于彩涂压型钢板构件设计中的选材问题

近年来 ,在彩涂压型钢板构件设计应用中 ,由于不重视、不了解如何合理选材 ,在实际工程的材料订货中也都不提出对材料性能的技术要求 ,致使供货材质、材性不能满足使用要求 ,存在降低彩板构件承载力或减少其使用寿命的隐患 ,应引起设计人员的注意。同时对当前如何按使用条件及材料供应条件合理地选定彩板材料的性能技术要求 ,包括基板钢材的级别及力学性能、板厚及公差控制要求、镀锌层质量与彩涂层类别以及参照的技术标准等 ,提出了一些建议 ,供设计应用参考。最后还对板的强度、厚度以及镀铝锌板的选用问题进行了讨论     

MCM用氮化铝共烧多层陶瓷基板的研究

通过实验优化AlN(氮化铝)瓷料配方及排胶工艺,对共烧W(钨)导体浆料性能及AlN多层基板的高温共烧工艺进行了研究,并对AlN多层基板的界面进行了扫描电镜分析。采用AlN流延生瓷片与W高温共烧的方法,成功地制备出了高热导率的AlN多层陶瓷基板,其热导率为190 W/(m·K),线膨胀系数为4.6106℃1(RT~400℃),布线层数9层,W导体方阻为9.8 m,翘曲度为0.01 mm/50 mm,完全满足高功率MCM的使用要求。     

Growth of Ga x In1−x As y P1−y using ethyldimethylindium andt-butylphophine

The growth of GaInAsP lattice matched to GaAs using tertiary-butylphosphine and ethyldimethylindium to replace the more conventional phosphine and trimethylindium is described. The quaternary compound lattice matched to GaAs has received far less attention than related compositions that lattice match InP. Using the new sources, most of the growth problems experienced by previous workers have been avoided. Uniform compositions have been grown reproducibly without evidence of gas-phase, adduct-forming reactions. Bothn- andp-type films have been grown. Heteroepitaxy of high quality GalnAsP layers on Ge has also been achieved, and microstructural results are presented.     

Batch cultures of Penicillium camembertii on glucose and amino acids—model for growth and ammonium production

BACKGROUND: Three groups of amino acids were previously characterized based on their ability to be assimilated as carbon source by Penicillium camembertii. To describe the diauxic growth recorded on glucose and amino acids from the second group, such as arginine, an unstructured model was previously developed, based on the sequential consumption of both carbon substrates, glucose, followed after its exhaustion, by arginine. The model was modified to describe also the behaviour recorded during growth on other amino acids. RESULTS: The growth model involved the carbon substrate consumption (Verlhust model) and the biomass on carbon substrate yield. Glucose was therefore considered during P. camembertii growth on nitrogen source amino acids (lysine—first group); and amino acid consumption was considered during growth on carbon source amino acids (glutamate—third group), with glucose being dissimilated only for energy supply. The excess nitrogen from amino acids was released as ammonium; the linking of this production to growth was found to increase with the ability of the amino acid to be assimilated as carbon source by P. camembertii. CONCLUSION: The various metabolic behaviours recorded during P. camembertii growth on amino acids, in the presence of a primary carbon source such as glucose, were proved to be satisfactorily described by the model, showing the robustness of the model. Copyright © 2007 Society of Chemical Industry     

Germanium islands embedded in strained silicon quantum wells grown on patterned substrates

Germanium islands were embedded in strained silicon quantum wells in order to provide an improved electron confinement in vicinity of the islands. Growth was performed on relaxed SiGe layers. Patterned substrates were used, favouring lattice relaxation as well permitting the fabrication of small Ge islands at deposition temperatures above 500 °C. Photoluminescence analysis reveals a strongly reduced dislocation related signal. The low temperature spectra are dominated by intense signals from the germanium islands. The origin of these signals were investigated by removing the islands by etching, analysing reference samples without a silicon quantum well, varying the germanium deposition and the growth temperature.