Microstructure and mechanical properties of Ti 45Al 5Nb + (0–0.5C) sheets

The possible application of gamma titanium aluminides in aerospace industry requires a detailed understanding of the microstructure–property relationship of sheets made from this material. This paper reports the mechanical properties of sheets up to 1000 °C, based on alloy concepts with high Nb concentrations and small additions of C. Sheets were manufactured by rolling powder metallurgical compacts with compositions Ti 45Al 5Nb and Ti 45Al 5Nb 0.5C. The microstructures of both sheets are “near gamma” and consist of γ-TiAl and ₂-Ti₃Al phases. The texture of both phases is very weak. The strengths levels are very high and that of the C-containing sheet exceeds that of the C-free material at RT by 200 MPa. The mechanical properties of Ti 45Al 5Nb are independent of the direction in the sheet, in the whole temperature range from RT to 1000 °C. However, for the C-containing sheet this is true only in the upper temperature range.     

陶瓷树脂内衬复合钢管介绍

采用树脂材料密暑离心铝热法制备陶瓷瓷钢管内衬层气孔，从而获得具有防护耐磨双重功能的复合管材。产品内衬层与钢管基体结合强度高，可在真空状态下长期运行，在高温下内初不鼓泡、不折皱。     

A simple nutrient-tolerance (NT) test for the characterization of the different types of oligocarbotolerant and oligocarbophile water bacteria from non-carbonated mineral water

Comparative determination of the specific growth kinetics in mineral water and low and higher concentrated broths at 20 degrees C of 25 selected Gram-negative bacteria isolated from natural non-carbonated mineral water yielded three groups: (1) facultative oligocarbotolerants--with faster growth in normal broth (In g l-1: yeast extract 2.5; casein peptone 5.0; glucose 1.0); (2) obligate oligocarbotolerants--with equal rates of growth in normal and 1:10 diluted broth; and (3) oligocarbophiles--with faster growth in 1:10 diluted broth and in mineral water. In addition, three nutrient types, 'eu-, meso- and oligotrophic' could be distinguished on the basis of full, weak and no growth in brain-heart infusion broth. Further characterization was made between slow and very slow growth types in 1:10 diluted broth. All 25 isolates were psychrotrophic with a minimum growth temperature below 0 degree C. The optimum and maximum temperatures of growth in 1:10 diluted broth, as determined in a temperature gradient incubator were between 20 and 32, and between 29 and 34 degrees C with an average of 26 and 31 degrees C, respectively. Based on these results a very simple nutrient-tolerance test was proposed. After inoculation of the three media, 1:10 diluted broth, normal broth and brain-heart infusion, it is only necessary to check whether or when visible turbidity occurs during 2 weeks incubation at 20 degrees C. This allows additional characterization of bacteria from natural mineral water, which are often difficult to identify, on the basis of growth characteristics in various types of nutrient media.     

1.5 mu m band travelling-wave semiconductor optical amplifiers with window facet structure

1.5 mu m band travelling-wave semiconductor optical amplifiers (TWAs), characterised by their window facet structure and symmetrised active waveguide, have been developed. 1.5 dB spectral gain ripple and 1.3 dB TE-TM mode gain difference at 22 dB signal gain were achieved simultaneously. An average facet reflectivity as low as 0.06% was estimated.<>     

A new 4H-SiC normally off lateral channel vertical JFET with extremely low power losses: source inserted double-gate structure with a supplementary highly doped region

A novel silicon carbide (SiC) normally off lateral channel vertical junction field-effect transistor (LC-VJFET), namely a source-inserted double-gate structure with a supplementary highly doped region (SHDR), was proposed for achieving extremely low power losses in high-power switching applications. The proposed architecture was based on the combination of an additional source electrode inserted between two adjacent surface gate electrodes and a unique SHDR in the vertical channel region. Two-dimensional numerical simulations for the static and resistive switching characteristics were performed to analyze and optimize the SiC LC-VJFET structures for this purpose. Based on the simulation results, the excellent performance of the proposed structure was compared with optimized conventional structures with regard to total power losses. Finally, the proposed structure showed about a 20% reduction in on-state loss (P/sub on/) compared to the conventional structures, due to the effective suppression of the JFET effect. Furthermore, the switching loss (P/sub sw/) of the proposed structure was found to be much lower than the results of the conventional structures, about a 75% /spl sim/ 95% reduction, by significantly reducing both input capacitance (C/sub iss/) and reverse transfer capacitance (C/sub rss/) of the device.     

Correlation analysis for non-invasive quantitative monitoring of biological activity of recombinant enzyme using green fluorescence protein in Escherichia coli under various culture environments

Monitoring of biological activity for target enzyme is important for its production in recombinant expression systems. Previously, we demonstrated that green fluorescent protein (GFP) as a fusion partner is successfully tooled for facile, in vivo, and non-invasive quantification of target enzyme levels based on a linear relationship between GFP fluorescence and enzyme (chloramphenicol acetyltransferase; CAT) activity. Here, we investigated the effects of culture environmental variations (initial glucose amount, surface aeration, and inducer concentration) on correlation between GFP fluorescence and CAT activity, and established a general linear correlation as a unique criterion for quantitative monitoring of CAT biological activity. This general correlation for GFP fusion strategy can be applied for non-invasive and on-line monitoring of recombinant enzyme production under various culture conditions without further experimental calibrations.     

Influence of Si<Subscript>3</Subscript>N<Subscript>4</Subscript> passivation on surface trapping in SiC metal-semiconductor field-effect transistors

The SiC metal-semiconductor field-effect transistors (MESFETs) have been reported to have current instability and strong dispersion caused by trapping phenomena at the surface and in the substrate, which degrade direct-current (DC) and radio-frequency (RF) performance. This paper illustrates the change in electrical characteristics of SiC MESFETs after Si₃N₄ passivation. Because of a reduction of surface trapping effects, Si₃N₄ passivation can diminish current collapse under pulsed DC conditions, increasing the RF power performance. The reduction of surface trapping effects is verified by the change in the ratio of the drain current to the gate current under pinch-off conditions.     

Tertiary treatment of biologically treated piggery wastewater using vibratory shear-enhanced RO membrane.

This study presents a good example for the tertiary treatment of biologically treated piggery wastewater using vibratory shear enhanced RO membrane (VSEP RO). Through a simple process combination, utilizing Bioceramic SBR(BCS) and VSEP RO, at Gimhae plant livestock wastewater is treated excellently to meet the strict effluent standards. Application of RO membrane directly to the biologically treated effluent has been successful without any pretreatment to reduce high suspended solids. The combination of VESP UF followed by RO filtration processes produced a higher recovery rate in the 3-week pilot test.     

关于城市照明维护质量考核指标体系探讨

城市道路照明是支撑城市正常运行和健康发展的基础,是重要的城市基础设施,对改善人居环境、促进社会经济发展意义重大。目前,道路照明维护质量考核无真正可以量化或可执行的考核依据,严重制约了道路照明维护质量,本文针对道路照明设施的维护质量考核体系进行探讨。     

Bendable and Splitter-Integrated Optical Subassembly Based on a Flexible Optical Board

A bendable and splitter-integrated optical subassembly (OSA) is suggested as a short-distance board-to-board optical interconnection. This OSA was fabricated by simply packaging a vertical-cavity surface-emitting laser on a flexible optical board having an embedded 1 $times$ 8 optical splitter waveguide. Finally, we measured various optical characteristics of the OSA, including insertion, twist, and bending losses.