Calculation of Some Properties of the Cubic Oxides of II-VIII Group Metals

Experimental data on the bulk modulus of elasticity, thermal expansion coefficient, specific heat capacity, specific volume, Grueneisen constant, and atomization energy of the cubic monoxides of Mg, Ca, Sr, Cd, Ba, Eu, Th, U, Pu, Ti, Zr, V, Nb, Ta, Cr, Mn, Fe, Co, and Ni were analyzed. Using six correlation relationships values of unknown properties and adjusted values of known properties at 298 K were calculated.

     

铝含量对封严涂层用铜铝骨架合金热性质影响的第一性原理计算

CuAl 合金是重要的可磨耗封严涂层骨架材料,Al 含量会对涂层的性能产生显著影响。为了明确不同 Al 含量对可磨耗封严涂层的热性能产生的影响,文章采用基于密度泛函理论的第一性原理方法,使用特殊准随机结构对 Al 含量从 0 至 18.750at.% 的 α 相的铜铝二元合金进行了建模,并结合准谐近似方法研究了其弹性常数、熔点、热膨胀系数、比热容等性质。利用真空感应熔炼法制备了 Al 名义含量为11.0at.%、15.0 at.%、18.9 at.% 三组不同组分的铜铝合金,对其熔点、热膨胀系数与比热容进行了实验表征。计算结果表明,随着 Al 含量的增加CuAl 无序固溶体的熔点呈下降趋势,CuAl 合金的热膨胀系数呈升高趋势,CuAl 合金的定压比热容先升高后降低,计 算值与实验测量值符合良好。本工作可以为铜铝合金涂层成分设计提供一定理论与实验数据参考。     

Determination of Honeycomb Material Properties: Existing Theories and an Alternative Dynamic Approach

This paper examines several available analytic and experimental methods to determine the orthotropic material properties of honeycomb. Fifteen published sets of simple equations for the material properties were reviewed and their values calculated for a specific honeycomb aluminum core. The same core was tested with ASTM standard methods and the agreement between the theoretical material properties and the experimental results was considered. To reduce the time and cost for the experimental determination, a simple technique for measuring the main dynamic material properties of honeycomb is introduced. A good agreement was found between the major theoretical out-of-plane material properties of honeycomb, the experimental ASTM methods, and the presented dynamic approach.     

Specification Requirement for Thermal Stability of Sintered NdFeB Materials for Electrical Machines

Based on IEC standards and Chinese national standards of sintered NdFeB materials, in the paper the hightemperature, room-temperature properties and thermal stability of about one hundred samples of NdFeB materials for electrical machines were measured and analyzed.These materials are produced by ten representative manufactories in China.Combined with the analysis results, the paper points out that the magnetic properties of sintered NdFeB materials for electrical machines should meet not only the specific values in standards, such as Br, (BH)max ,HcJ ,but also the requirement of temperature coefficients a (Br) , a (HcJ).     

Modeling Hydrological Processes in Hillslope Watershed of Humid Tropics

Hydrological studies were conducted in a lateritic hillslope watershed of Kerala, a humid tropical region in India. The watershed characteristics, soil moisture properties, and hydrological processes were evaluated. The prominent mechanisms of runoff generation were identified as saturated through flow and saturated source areas. A 2D lateral saturated flow model linked with a vertical column model was developed to simulate these hydrological processes. The model with calibrated effective values of hydraulic conductivity and specific yield was found to be capable of predicting the hillslope hydrological processes.     

Properties and Performance of a Pulverized Fly Ash Grout

A laboratory investigation was conducted in order to develop a new grout based on fly ash produced in Greece. Ptolemaida fly ash was selected because of its hydraulic properties and was pulverized (Blaine specific surface over 8,300 cm2/gr, D15 = 1.3?μm, D50 = 6?μm, and D85 = 20?μm) in order to improve its groutability and its hydraulic activity. Pulverized fly ash (PFA) suspensions with selected additives have properties comparable to those of ordinary and microfine cement suspensions. Clean sands were injected using two specially constructed devices. Hydraulic conductivity, unconfined compression, and UU and CU-PP triaxial compression tests were conducted on grouted sand specimens. Coarse sands can be grouted effectively with PFA suspensions. Conventional groutability ratios were found to overestimate the groutability of these suspensions. Grouting with PFA suspensions reduces sand hydraulic conductivity by up to seven orders of magnitude and yields unconfined compression strength values up to 3,000 kPa. The Mohr–Coulomb failure criterion represents the behavior of grouted sand with cohesion values ranging from 280 to 450 kPa and angle of internal friction slightly higher than that of the sands.     

Laws of change in certain properties of borides of transition metals

An analysis of available experimental data on thermal and elastic properties of (U, Pu, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo)—diborides and (Sc, Y, lantanides)—hexaborides is carried out. With the help of correlative relations, mutually corresponding values of thermal expansion, bulk modulus of elasticity, specific heat capacity, and Gruneisen parameter of the above borides are calculated for 298 K.     

Partial properties of four glycosidases in normal human lens and variations in their enzyme activities during aging and with the advance of lens coloration

This paper reports the active glycosidases in normal human lenses and their partial properties. In addition, variations in their enzyme activities during aging and with the advance of lens coloration were also examined. Five glycosidases, alpha-glucosidase, beta-D-glucuronidase, N-acetyl-beta-D-glucosaminidase, beta-D-cellobiosidase, and alpha-L-fucosidase, were detected as active glycosidases in the normal human lens. However, the activity of beta-D-cellobiosidase was considerably low as compared to the other four glycosidases. Thus, this enzyme was omitted from this study. The four glycosidases, alpha-D-glucosidase, beta-D-glucuronidase, N-acetyl-beta-D-glucosaminidase, and alpha-L-fucosidase, showed that their enzyme activities fell abruptly between the ages of 40 and 50. Furthermore, the Km values of their enzymes exhibited some variability during aging. Namely, the Km values of their enzymes indicated the lowest value between the 40 age group and 50 age group, suggesting that the substrate affinity became the strongest at these age groups. Then, variations in enzyme activity with the advance of lens coloration were examined. In each cases, the specific activity of detectable glycosidases in color lenses, white to brown, decreased. In particular, the specific activity of enzymes in the brown lens was very low, indicating that glycosidases in the brown lens may scarcely display their enzyme activities.     

Rare earth nanostructures based on PrO_x/CNT composites as potential electrodes for an asymmetric pseudocapacitor cell

Rare earth metal oxides have been widely used as pseudocapacitor electrodes owing to their unique physical and electronic properties.The present paper reports the synthesis and pseudocapacitor applications of praseodymium oxides,owing to their unique physical properties.PrO_x/unzipped carbonnanotubes were synthesized following a hydrothermal approach.Detailed morphological as well as electrochemical analyses were performed to elucidate how the unique properties of PrO_x affect the charge storage ability.Special emphasis was given on the effect of anion intercalation due to the surface oxygen vacancies in PrO_x which would contribute towards the pseudocapacitive energy storage.Oxygen intercalation was exploited for the first time in fluorite crystals for fast energy storage and a specific capacitance value as high as 1099 F/g was obtained with the electrodes.An asymmetric supercapacitor prototype was also fabricated with a V_2 O_5/graphene counter electrode and the energy and power density values obtained are as high as 52.08 Wh/kg and 2.9 kW/kg,respectively.     

氧化石墨烯掺杂量与pH值对石墨烯气凝胶储能性能的影响

采用溶胶凝胶法制备石墨烯气凝胶（GA）,并研究了前驱液中的pH值与氧化石墨烯（GO）的质量分数对GA材料储能性能的影响。使用X射线粉末衍射（XRD）、X射线光电子能谱（XPS）、氮气吸脱附分析、扫描电子显微镜（SEM）对样品微观结构与形貌进行表征。用循环伏安（CV）、恒流充放电（CP）、电化学交流阻抗（EIS）测试了样品的电化学性能。结果表明,前驱液中的pH值及GO质量分数的不同会影响GA中团簇颗粒的大小和数量,进一步影响GA三维结构。在pH值为6.3、GO 的质量分数为1%时,制得的GA比表面积最大为530 m2?g?1,在1 A?g?1的电流密度下比电容高达364 F?g?1。此外,将该材料制成对称超级电容器具有高的库伦效率,在1 A?g?1下进行CP测试,得到电容器的比电容为98 F?g?1,循环800次后其循环稳定性能为初始比电容值的95.9%。      

Thermophysical Properties of Platinum-Copper Alloys

Platinum and copper along with their alloys have been used in a broad range of applications including jewelry, coinage, electrical and electronic devices, and many others. Their thermophysical properties play an important role in casting processes and are required as input data for casting simulation. The focus of this work was to investigate these properties by different methods. Platinum, copper, and four platinum-copper alloys, namely, Pt96Cu04, Pt68Cu32, Pt50Cu50, and Pt25Cu75, were investigated within this work. The melting range and thermal expansion were measured at fem by differential scanning calorimetry and dilatometry, respectively. At TU Graz, wire-shaped samples were investigated by an ohmic pulse heating technique. This technique delivers thermophysical properties of electrically conducting materials far into the liquid phase. These measurements allow the calculation of specific heat capacity and the temperature dependencies of electrical resistivity, enthalpy, and density of these alloys in the solid and liquid phases. Thermal conductivity and thermal diffusivity as a function of temperature are estimated from resistivity data using the Wiedemann?CFranz law at the end of the solid phase and at the beginning of the liquid phase. The results are compared with the available literature values.     

Human skeletal muscle mitochondria in aging: lack of detectable morphological and enzymic defects

We have investigated structural and functional properties of skeletal muscle mitochondria obtained from biopsies from young and old individuals. The morphometric analysis of muscle sections revealed a tendency to an increase of total area, numerical density and volume density of mitochondria in the aged. The enzymatic activities of NADH-Coenzyme Q reductase, succinate cytochrome c reductase, ubiquinol-cytochrome c reductase exhibited a high variability of specific activities without any correlation with age. Expression of the values as enzyme turnovers reduced the variability but was unable to reveal any age-dependent modification.     

稀土对呋喃树脂-柔性石墨复合材料性能的影响

本文研究了不同种类稀土对呋喃树脂－柔性石墨复合材料性能的影响。结果表明，复合材料的肖氏硬度、电阻率、压缩率及回弹率明显地依赖于稀土种类与用量，在本实验条件下加入０．９％（ｗｔ）ＣｅＯ２时，材料的综合性能最佳；而体积密度基本不受ＣｅＯ２用量影响。结合表面形貌ＳＥＭ分析，从稀土活性中心对树脂与石墨之间界面粘结力的影响以及稀土对树脂固化过程的助催化两方面初步探讨了稀土的作用机理。     

Phosphoglycerate kinase from young and old Turbatrix aceti

Phosphoglycerate kinase (ATP:3-phospho-D-glycerate-1-phosphotransferase, EC 2.7.2.3) from young and old Turbatrix aceti has been purified to homogeneity. The "old" enzyme exhibits a marked reduction in specific activity both in crude homogenates and in pure form when compared to preparations from young nematodes. The specific activities for pure "young" and "old" enzymes are 650-750 and 300-400 units/mg, respectively. All other properties of "young" and "old" enzymes were nearly identical, including molecular weight (43 000), Km, behavior on columns, thermal stability and mobility during gel electrophoresis at three pH values. The results are discussed in terms of the possible mechanism of formation of "altered" enzymes. In addition, certain properteis of the nematode phosphoglycerate kinase are compared with those of the enzyme from yeast and rabbit muscle.     

In times of survival, the right of silence

The purpose of this study was to assess cortical and cancellous bone responses to unilateral limb immobilization and, subsequently, to remobilization with exercise, in a young adult canine model. Right forelimbs of 14 1-2-year old mongrel dogs were immobilized in a non-weight-bearing position by a bandage for 16 weeks. Six control dogs were untreated. At 16 weeks, seven immobilized and three control dogs were euthanized. The remaining seven immobilized dogs began a recovery protocol consisting of 16 weeks of kennel confinement (without the right forelimb bandaged) followed by 16 weeks of treadmill exercise conducted three times per week. These seven dogs and three control dogs were euthanized at 48 weeks. Bone mineral density of the proximal radii was determined with dual-energy X-ray absorptiometry and humeral middiaphyseal cross-sectional areas were determined with computed tomography. Humeri were tested in cranio-caudal three-point bending to failure. Cancellous bone cores from the lateral humeral condyles had wet apparent density determined and were tested to failure in compression. Mechanical properties, bone density, and cross-sectional areas were compared between immobilized (right forelimb), contralateral weight bearing (left forelimb), and control forelimbs with Kruskal-Wallis and post hoc tests. At 16 weeks, bone mineral density, cortical load, yield, and stiffness as well as cancellous bone failure stress, yield stress, and modulus were significantly lower (p < 0.02) for immobilized limbs than control limbs. Immobilized limb cancellous bone mechanical properties were 28%-74% of control values, and cortical bone mechanical properties were 71%-98% of control values. After 32 weeks of remobilization, cortical and cancellous bone mechanical properties were not different from control values except that cortical bone failure stress and modulus were significantly higher (p < 0.01) between remobilized and control limbs. In summary, 16 weeks of forelimb immobilization was associated with significantly lower mechanical properties, and with greater differences in cancellous than cortical bone properties. Mechanical properties were not different from control values after 32 weeks of recovery that included 16 weeks of treadmill exercise.     

Effects of zinc deficiency on protein synthesis and expression of specific mRNAs in rat liver

The effects of zinc deficiency on protein synthesis and expression of specific mRNAs were assessed in rat liver. Zinc deficiency had no apparent effect on liver weight, protein content, or RNA content when these properties were compared with values obtained using pair-fed rats. However, zinc deficiency resulted in a lower rate of hepatic protein synthesis. The decreased rate of protein synthesis was due to a decrease in the rate of synthesis of proteins retained in the liver, with no apparent change in the synthesis of secreted proteins. Analysis of expression of specific gene products, as assessed by in vitro translation of total RNA followed by two-dimensional gel analysis, showed that the expression of only a few mRNAs was altered by zinc deficiency. The patterns of change in gene expression resulting from zinc deficiency varied from almost complete repression to full expression. In additional studies, cDNA clones to serum retinol-binding protein and transthyretin were used to examine the effect of zinc deficiency on the relative abundance of mRNA for these two proteins. The relative abundance of mRNA for transthyretin was specifically elevated as a result of zinc deficiency. In contrast, the relative abundance of mRNA for hepatic serum retinol-binding protein was increased in both zinc-deficient and pair-fed rats. Therefore, the observed change in mRNA for serum retinol-binding protein was apparently at least in part due to the inanition that accompanies zinc deficiency. Overall, the results suggest that zinc can regulate the synthesis of specific proteins in rat liver through changes in the relative abundance of specific mRNAs.     

A multisample assay for inhibitors of phosphatidylinositol phospholipase C: identification of naturally occurring peptide inhibitors with antiproliferative activity

A convenient and reliable multisample assay for the screening of inhibitors of the growth factor signalling enzyme phosphatidylinositol specific phospholipase C (PtdInsPLC) has been developed. Three naturally occurring peptide inhibitors of PtdInsPLC have been identified, myroridin K, streptothricin B and edeine, with IC50 values of 8.3, 6.7 and 16.1 microM, respectively. All three peptides inhibited colony formation of HT-29 human colon adenocarcinoma cells, with IC50 values of 7.2, 3.9 and 13.0 microM, respectively. The compounds also inhibited the growth of other human cancer cells in culture. One of the peptides, myroridin K, has previously been reported to have in vivo antitumour activity. It is possible that inhibition of PtdInsPLC is responsible for the cell growth inhibition and antitumour properties of the peptide compounds.     

Modeling Concrete Masonry Walls Subjected to Explosive Loads

Concrete masonry unit walls subjected to blast pressure were analyzed with the finite element method, with the goal of developing a computationally efficient and accurate model. Wall behavior can be grouped into three modes of failure, which correspond to three ranges of blast pressures. Computational results were compared to high-speed video images and debris velocities obtained from experimental data. A parametric analysis was conducted to determine the sensitivity of computed results to critical modeling values. It was found that the model has the ability to replicate experimental results with good agreement. However, it was also found that, without knowledge of actual material properties of the specific wall to be modeled, computational results are not reliable predictors of wall behavior.     

三元乙丙橡胶老化与气候关联性及老化程度全国分布预测

利用三元乙丙橡胶(EPDM)在我国11个典型大气站点暴晒3年的老化数据及气候环境数据,基于对EPDM老化行为分析以及气候环境对EPDM作用机制,探究EPDM老化与气候因子之间的关联性.通过因子分析与逼近理想解排序法,将多个老化指标转化为综合老化值;由灰色关联度分析,得到影响EPDM老化的关键气候因子为辐照度、湿度、温度和降雨;通过BP人工神经网络,建立EPDM综合老化值与气候因子间关联模型.利用我国97个地市级城市气象数据,预测EPDM在未试验地区综合老化值,可视化得到EPDM在我国的老化分布图.图形表明,EPDM在我国西部地区,新疆南部、云南南端、广东南部、海南、台湾等地区老化程度较严重.