Butters Varying in <Emphasis Type="Italic">trans</Emphasis> 18:1 and <Emphasis Type="Italic">cis</Emphasis>-9,<Emphasis Type="Italic">trans-</Emphasis>11 Conjugated Linoleic Acid Modify Plasma Lipoproteins in the Hypercholesterolemic Rabbit

The experiment was designed to study the effects of butters differing in conjugated linoleic acid (CLA) and trans 18:1 contents on lipoproteins associated with the risk of atherogenesis. New Zealand White male rabbits (9.6 weeks; 2.1 kg) were assigned for 6 or 12 weeks to three diets (n = 6 per diet) made of conventional pellets with 0.2% cholesterol and with 12% fat provided from a butter poor in trans-10 and trans-11 18:1 and in CLA (standard group), or rich in trans-10 18:1 (trans-10 18:1 group) or rich in trans-11 18:1 and in cis-9,trans-11 CLA (trans-11 18:1/CLA group). Blood samples were collected at the end of dietary treatments. Lipoproteins were separated by gradient-density ultracentrifugation. Lipid classes were determined enzymatically and apolipoproteins A-I and B by radial immunodiffusion. Mainly in the 12-week rabbits, higher plasma triglycerides and apolipoprotein B levels shown in the standard and trans-10 18:1 groups compared with those in the trans-11 18:1/CLA group are associated with higher plasma levels of very low density lipoproteins (VLDL) and low density lipoproteins (LDL) also shown in these two groups. In the 12-week rabbits, a shift towards denser LDL, considered as more atherogenic, was shown only in the trans-10 18:1 group. In these animals, the VLDL + LDL to HDL ratio was 1.7-2.3 times higher in the trans-10 18:1 group than in the other groups (P = 0.076). These results suggest a rather neutral effect of trans-11 18:1/CLA butter towards the risk of atherogenesis, whereas trans-10 18:1 butter would tend to be detrimental.     

胶粘剂在刀具制造中的应用

在自动化生产中,金属切削刀具在使用条件下的质量大多数情况下取决于刀片的夹固方法。若采用粘接技术,则既可以避免传统夹固方法的一些缺点,又可以省去一些工序,如铣、磨、钳工加工等等工序。然而用胶粘剂来装配刀具的方法仍未能得到广泛的应用,这是因为已知牌号的胶粘剂不具备足够的物理饥饿性能。当研制出用含碳和有机硅的化合物改往的一系列高强度胶粘剂之后,大大地扩大了刀具胶接接头的使用温度范围。表中示有在较高温度下一些切削工具用胶粘剂的物理一机械性能试验结果。     

Thermoelectric properties of Bi_（1.5）Pb_（0.5）Sr_（2-x）La_xCo_2O_y polycrystalline materials

Polycrystalline samples of Bi 1.5 Pb 0.5 Sr 2-x La x Co 2 O y (x = 0.1, 0.2, 0.3) with a layered structure were prepared by solid-state reaction method. All samples are p-type semiconductors. The thermoelectric properties, namely, the electric resistivity (ρ), Seebeck coefficient (S), and power factor (S 2 /ρ) of the samples are dependent on chemical composition. The values of ρ, S, and S 2 /ρ increase with an increase in temperature for all samples. The substitution of Pb 2+ for Bi 3+ and La 3+ for Sr 2+ improves the thermoelectric properties of the Bi 2 Sr 2 Co 2 O y system owing to the simultaneous decrease of electric resistivity and increase of Seebeck coefficient. As a result, the optimal thermoelectric property has been obtained in Bi 1.5 Pb 0.5 Sr 1.7 La 0.3 Co 2 O y and the power factor can reach 2.1 × 10-4 W·m-1 K-2 at 998 K.     

The effect of lactose, NaCl and an aero/anaerobic environment on the tyrosine decarboxylase activity of Lactococcus lactis subsp. cremoris and Lactococcus lactis subsp. lactis

The aim of this work was to study, under model conditions, combined effects of the concentration of lactose (0-1% w/v), NaCl (0-2% w/v) and aero/anaerobiosis on the growth and tyramine production in 3 strains of Lactococcus lactis subsp. lactis and 2 strains of L. lactis subsp. cremoris. The levels of the factors tested were chosen with respect to the conditions which can occur during the real process of natural cheese production, including the culture temperature (10 ± 1 °C). In all strains tested, tyrosine decarboxylation was most influenced by NaCl concentration; the highest production of tyramine was obtained within the culture with the highest (2% w/v) salt concentration applied. Two of the strains L. lactis subsp. lactis produced tyramine only in broth with the highest NaCl concentration tested. In the remaining 3 strains of L. lactis, tyramine was detected under all conditions applied. The tested concentration of lactose and aero/anaerobiosis had a less significant effect on tyramine decarboxylation. However, it was also found that at the same concentrations of NaCl and lactose, a higher amount of tyramine was detected under anaerobic conditions. In all strains tested, tyramine decarboxylation started during the active growth phase of the cells.     

高能脉冲精密冷补技术用于修复零件表面局部缺损

高能脉冲精密冷补技术由于其独特的能量输出方式,在实现金属零件表面修复时具有修复速度快、热量输入小和结合强度高的特点。通过对液压柱塞杆划伤表面的实际修复和修复区域的性能测试,结果表明:修复层与基体无明显气孔,结合紧密,HAZ宽度为130μm,修复层平均显微硬度为520 HV,耐磨性能较基体提高36.4%。说明高能脉冲精密冷补技术是一种操作简单,性能可靠的新型修复技术。     

MARTENSITIC AND R PHASE TRANSFOR MATIONS IN NiTiand NiTiHf

１　ＩＮＴＯＤＵＣＴＩＯＮＳｈａｐｅｍｅｍｏｒｙａｌｌｏｙｓ（ＳＭＡｓ）ａｒｅｅｘｃｅｌｌｅｎｔｃａｎｄｉｄａｔｅｓｆｏｒｃｏｎｔｒｏｌｓｙｓｔｅｍｓａｎｄａｒｅｃｏｍｍｏｎｌｙｒｅｆｅｒｒｅｄｔｏａｓ“ｓｍａｒｔ”ｍａｔｅｒｉａｌｓｄｕｅｔｏｔｈｅｉｒａｂｉｌｉｔｙｔｏｃｈａｎｇｅｓｈａｐｅｗｉｔｈｔｅｍｐｅｒａｔｕｒｅ．Ｔｈｅｓｅａｌｌｏｙｓｃａｎａｌｓｏｇｅｎｅｒａｔｅｓｉｇｎｉｆｉｃａｎｔａｍｏｕｎｔｓｏｆｓｔｒａｉｎ（ａｎｄｓｔｒｅｓｓ）ａｎｄａｒｅｉｄｅａｌｆｏｒｕｓｅｉｎａｃｔ…     

Ultrasensitive determination of polycyclic aromatic compounds with atmospheric-pressure laser ionization as an interface for GC/MS

Recently we introduced atmospheric pressure laser ionization (APLI) as a complementary ionization method for coupling LC-MS systems (HPLC and CEC), allowing ionization of nonpolar aromatic compounds via near-resonant two-photon excitation. In this paper, we demonstrate that APLI with the same source enclosure as for LC coupling is also suited for hyphenation of GC with atmospheric-pressure ionization mass spectrometry. This technique permits the qualitative and quantitative determination of aromatic compounds in an ultralow concentration range, as we show here with polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs, and hetero-PAHs as examples. The outstanding sensitivity is demonstrated for chrysene, with a detection limit of 22 amol. Polar functional groups reduce the sensitivity, but after methylation or silylation, the analytes can also be determined very sensitively in complex matrixes, as is shown with 1-hydroxypyrene in urine.     

基于统计模型及有限元法的重力坝变形模量反演

鉴于坝体和坝基力学参数选择的合理性对大坝结构分析及安全评价指标拟定的重要性,结合实际监测资料,提出了基于统计模型和有限元法进行重力坝坝体和坝基变形模量反演的方法,在分析地基范围取值、坝体变形模量取值对坝基变形模量反演影响的基础上,建立合适的有限元模型和统计模型,通过有限元计算拟合实测资料中的水压分量,根据最小二乘法原理反演大坝变形模量。将基于统计模型和有限元法反演混凝土重力坝变形模量的方法应用于某实际工程,结合实测资料反演了典型坝段坝基和坝体的变形模量,计算结果合理可信,精度较高。     

基于综合判据的重力坝深层抗滑稳定性分析

为研究层状岩体坝基上的重力坝深层抗滑稳定性,以某混凝土重力坝溢流坝段为例,采用单软弱夹层分析法和双软弱夹层分析法两种建模方法,综合D-K曲线特征、相关性检验结果、塑性区分布以及接触面状态分析,确定了坝基的深层抗滑稳定安全系数,进而揭示了地基塑性破坏导致坝体失稳的机理。     

消除混凝土坝应力网格效应的三次等效应力法

针对混凝土坝有限元等效应力在角缘部位的失真问题,基于挡水结构的弹性力学解,提出一种改进三次等效应力法,即选取三次多项式模拟混凝土坝水平截面的正应力分布,确定多项式的待定系数,得到三次等效应力分布形式。以混凝土重力坝和拱坝为例,分别以线弹性有限元法、线性等效应力法、改进的三次等效应力法计算混凝土坝建基面的法向正应力和主应力,结果表明改进的三次等效应力法计算结果不仅有效减小了对计算网格的依赖性,且与线弹性有限元计算结果相当接近。结果可为混凝土坝的安全性评价提供参考。