INFLUENCE OF SURFACE-ACTIVE ELEMENTS ON FLUID FLOW OF MIG WELDPOOL

A mathematical model describing the behavior of metal inert gas (MIG) welding isformulated in the paper. By means of numerical simulation, the influence of surface-active elements on fluid flow of MIG weldpool is studied. The calculation resultsshow that by adding surface-active elements, the fluid flow behavior is drasticallychanged and the flow fluid flows from lower to upper in vertical direction at the rearof weldpool (w>0). The physical phenomenon is explained from the viewpoint of fluidflow behavior of weldpool that the properties of weld metal is greatly improved andthe content of diffused hydrogen is reduced, thus providing a basis for developing newwelding materials.     

APPLICATION OF THE UNIFIED STATISTICAL MATERIAL DATABASE FOR DESIGN AND LIFE／RISK ASSESSMENT OF HIGH TEMPERATURE COMPONENTS

Statistical manipulation of material data was conducted for probabilistic life assessment or risk-based design and maintenance for high temperature components of power plants. To obtain the statistical distribution of material properties, dominant parameters affecting material properties are introduced into normalization of statistical variables. Those parameters are hardness, chemical composition, characteristic microstructural features and so on. Creep and fatigue properties are expressed by normalized parameters and the unified statistical distributions are obtained. These probability distribution functions show good coincidence statistically with the field database of steam turbine components. It was concluded that the unified statistical baseline approach is useful for the risk management of components in power plants.     

Si-Al COATING ON PURE MOLYBDENUM SUBSTRATE AND ITS CYCLIC OXIDATION BEHAVIOR

The halide-activated pack cementation method is utilized to codeposit aluminum and silicon on Mo substrate. Emphasis is placed on the microstructure and elevated-temperature oxidation resistance of coatings. The results show that hexagonal Mo (Si, Al)2 as a main phase and a little amount of the lower disilicide Mo3Si3 was formed on Mo substrate through the halide-activated pack cementation method. The resultant Si-Al coating on Mo substrate exhibits excellent cyclic oxidation resistance. The excellent cyclic oxidation resistance of the coatings is attributed to the formation of alumina on the coatings during the oxidation.     

金刚石有序排列锯片切割性能的研究

在金刚石锯片刀头表面上，金刚石颗粒的切割效率取决于金刚石颗粒之间的间距分布和单个金刚石的磨损状况。在这项研究中，试图分析金刚石颗粒之间的间距分布，在锯片的加工中，金刚石颗粒是人工有序排布的，将这种金刚石有序排列的锯片的切割特性与普通锯片的切割特性做了对比。金刚石颗粒的平均间距定为4mm，使用浓度为1．1ct/cm^3的美国40/50目的金刚石。在完成切割之后，在金刚石有序排列的锯片上，80％的金刚石颗粒可观测到其间距仍保持在2～6mm的范围内，     

Dietary intakes and food sources of fatty acids for Belgian women, focused on n-6 and n-3 polyunsaturated fatty acids

The intake of fat, saturated and monounsaturated FA (SFA and MUFA), and omega-6 and omega-3 PUFA has been estimated in 641 Belgian women (age 18-39 y). Their food intake was recorded using a 2-d food diary. The PUFA included were linoleic (LA), alpha-linolenic (LNA), arachidonic (AA), eicosapentaeonoic (EPA), docosapentaenoic (DPA) and docosahexaenoic (DHA) acids. The mean total fat intake corresponded to 34.3% of total energy intake (E). The mean intake of the FA groups corresponded to 13.7%, 13.1%, and 6.0% of E, for SFA, MUFA, and PUFA, respectively. The mean intake of LA was 5.3% of E and of LNA was 0.6% of E, with a mean LA/LNA ratio of 8.7. The mean intake of AA was 0.03% of E. The mean intake of EPA, DPA, and DHA was 0.4%, 0.01%, and 0.06% of E, respectively. According to the Belgian recommendations, the total fat and SFA intake was too high for about three-quarters of the population. The mean LA and overall n-6 PUFA intake corresponded with the recommendation, with part of the population exceeding the upper level. Conversely, the population showed a large deficit for LNA and n-3 PUFA. The major food source for LA and LNA was fats and oils, followed by cereal products. The main sources of long-chain PUFA were fish and seafood, and meat, poultry, and eggs. From a public health perspective, it seems desirable to tackle the problem of low n-3 PUFA intake.     

Diminished macrophage cholesterol removal rate by the altered HDL metabolism in the Nagase analbuminemic rat

Dyslipoproteinemia of the Nagase analbuminemic rat (NAR) is characterized by elevated concentrations of VLDL and LDL attributed to increased rates of liver lipoprotein synthesis. Increased lysophosphatidylcholine (LPC) in NAR HDL has been attributed to high plasma LCAT activity. We show here that, as compared with Sprague-Dawley rats (SDR), NAR plasma triacylglycerol (TAG), total cholesterol (TC), HDL TAG, protein, total phospholipids (PL), LPC, and PS are increased. These alterations rendered the NAR HDL particle more susceptible to the activity of the enzyme hepatic lipoprotein lipase (HL), which otherwise was unaltered in our study. Fractional catabolic rates in blood of the autologous ¹²⁵I-apoHDL (median and lower quartile values), were, respectively, 0.231 and 1.645 (n=10) in NAR as compared with 0.140 and 0.109 (n=10) in SDR (P=0.012), corresponding to synthesis rates of HDL protein of 89.8±33.7 mg/d in NAR and 17.4±6.5 mg/d in SDR (P=0.0122). Furthermore, Swiss mouse macrophage free-cholesterol (FC) efflux rates, measured as the percent [¹⁴C]-cholesterol efflux/6 h, were 8.2±2.3 (n=9) in NAR HDL and 11.2±3.2 (n=10) in SDR HDL (P=0.03). Therefore, in NAR the modification of the HDL composition slows down the cell FC efflux rate, and together with the increased rate of plasma HDL metabolism influences the reverse cholesterol transport system.     

Desaturation indices in liver, muscle, and bone of growing male and female mice fed trans-10, cis-12 conjugated linoleic acid

trans-10, cis-12-CLA (t10,c12-CLA) inhibits lipid deposition in adipose tissue of many species, but it also enhances lipid deposition in liver. We evaluated effects of dietary t10,c12-CLA content and gender on carcass composition, FA profile of selected tissues, and expression of FA synthase (FAS) and stearoyl-CoA desaturase-1 (SCD) mRNA in adipose tissue. Male and female (63 of each) CD-1 mice were assigned a diet containing 0.0, 0.15, or 0.30% t10,c12-CLA at 4 wk of age. Seven mice per dietary group within gender were sacrificed after 2,4 or 6 wk. The CLA isomer caused dose-dependent reductions in dry carcass weight and fat content, without altering protein content, but carcass fat and epididymal fat pad weights of males were reduced to a greater extent than carcass fat and inguinal fat pad weights of females. FAS and SCD mRNA in adipose tissue was more abundant in females than males, but expression in both genders decreased as the t10, c12-CLA content of the diet increased. Although the weight of gastrocnemius muscle was not influenced by diet, total FA content of the muscle of both genders decreased in response to dietary t10,c12-CLA content. Femur weight of male mice increased as the t10,c12-CLA content of the diet increased, but the weight increase was associated with a reduction in total FA content. The Δ9 desaturation indices for muscle and femur suggested a linear reduction in SCD activity, whereas Δ9 indices for liver indicated linear enhancement of SCD activity. Overall, results suggested that growing male mice were more susceptible than females to t10,c12-CLA inhibition of lipid deposition.     

锌-三氧化二铬复合镀层的特性

采用由氧化锌12g/L、氢氧化钠94 g/L、2-氨基-3-羧基吡啶4.2 g/L、四乙烯五胺17g/L、三乙醇胺2g/L、专利表面活性剂0.5 g/L及碳三氧化二铬(粒径2μm)0～ 11 g/L组成的镀液,于温度50℃、pH 6.5和电流密度4A/dm2的条件下,在低碳钢上电镀Zn-Cr2O3复合镀层.其显微硬度采...     

Preparation of Pt Ag alloy nanoisland/graphene hybrid composites and its high stability and catalytic activity in methanol electro-oxidation

In this article, PtAg alloy nanoislands/graphene hybrid composites were prepared based on the self-organization of Au@PtAg nanorods on graphene sheets. Graphite oxides (GO) were prepared and separated to individual sheets using Hummer's method. Graphene nano-sheets were prepared by chemical reduction with hydrazine. The prepared PtAg alloy nanomaterial and the hybrid composites with graphene were characterized by SEM, TEM, and zeta potential measurements. It is confirmed that the prepared Au@PtAg alloy nanorods/graphene hybrid composites own good catalytic function for methanol electro-oxidation by cyclic voltammograms measurements, and exhibited higher catalytic activity and more stability than pure Au@Pt nanorods and Au@AgPt alloy nanorods. In conclusion, the prepared PtAg alloy nanoislands/graphene hybrid composites own high stability and catalytic activity in methanol electro-oxidation, so that it is one kind of high-performance catalyst, and has great potential in applications such as methanol fuel cells in near future.