Development of a multidirectional simple shear testing device

A new simple shear testing device capable of applying multidirectional loading to soil specimens has been developed. The Texas A&M University multidirectional simple shear (TAMU-MDSS) device provides the ability to apply a large range of shear stresses and complex loading paths, such as figure-eight and circular patterns, to a cylindrical soil specimen confined by a wire-reinforced membrane. The load and torque experienced by the sample are directly measured by a multi-axis load cell installed above the specimen. Backpressure saturation of the specimen is made possible by the devicés ability to apply pressure in the chamber and backpressure to the water lines. Excess pore pressure is measured by a pressure transducer during the shearing phase of the testing. This paper describes the development of the TAMU-MDSS system and the capabilities of the device and presents test results on saturated clay soil specimens subjected to monotonic, unidirectional cyclic, and multidirectional loading. Copyright © 2013 by ASTM International.

Synthesis of biodiesel from waste cooking oil using immobilized lipase in fixed bed reactor

Waste cooking oil (WCO) is the residue from the kitchen, restaurants, food factories and even human and animal waste which not only harm people's health but also causes environmental pollution. The production of biodiesel from waste cooking oil to partially substitute petroleum diesel is one of the measures for solving the twin problems of environment pollution and energy shortage. In this project, synthesis of biodiesel was catalyzed by immobilized Candida lipase in a three-step fixed bed reactor. The reaction solution was a mixture of WCO, water, methanol and solvent (hexane). The main product was biodiesel consisted of fatty acid methyl ester (FAME), of which methyl oleate was the main component. Effects of lipase, solvent, water, and temperature and flow of the reaction mixture on the synthesis of biodiesel were analyzed. The results indicate that a 91.08% of FAME can be achieved in the end product under optimal conditions. Most of the chemical and physical characters of the biodiesel were superior to the standards for 0(#)diesel (GB/T 19147) and biodiesel (DIN V51606 and ASTM D-6751).

Lipase-catalyzed synthesis of biodiesel from acid oil in fixed bed reactor

Acid oil, which is a by-product in vegetable oil refining, mainly contains free fatty acids (FFAs) and acylglycerols and is a feedstock for production of biodiesel fuel now. The transesterification of acid oil and methanol to biodiesel was catalyzed by immobilized Candida lipase in fixed bed reactors. The reactant solution was a mixture of acid oil, water, methanol and solvent (hexane) and the main product was biodiesel composed of fatty acid methyl ester (FAME) of which the main component was methyl oleate. The effects of lipase content, solvent content, water content temperature and flow velocity of the reactant on the reaction were analyzed. The experimental results indicate that a maximum FAME content of 90.18% can be obtained in the end product under optimum conditions. Most of the chemical and physical properties of the biodiesel were superior to the standards for 0(#) diesel (GB/T 19147) and biodiesel (DIN V51606 and ASTM D6751).

稀土磷化物的制备及其性质研究

由于科学的发展和社会的需要、探索新的半导体材料、开辟稀土化合物的新用途成了重大的研究课题。众所周知，Ⅲ_a-Ⅴ_a族化合物是已被广泛应用的重要半导体材料。而对于Ⅲ_b-Ⅴ_a族化合物是否是半导体还在探索中。人们对Ⅲ_b-Ⅴ_a族化合物的磁学光学、电学性质及热电性质做了大量的研究。但是，对其是否是半导体未能得出一致的结论。Sclar等人总结了求Ⅲ-Ⅴ族化合物带宽度的公式，预言稀土单氮族化合物是半导体；Yim等人测量了稀土磷化物的吸收光谱，由此证实了其半导体性；Hasegawa用Apw法计算了GdX (x = N、P、As、Sb)的能带，计算得出GdP的能带重迭，故他认为LnP是金属性材料；(Ln=稀土元素）。Guntherodt测量了GdP晶体介电常数与波长关系，由此得出GdP是高载流了浓度材料，他由此解释了GdP电阻率低的现象，但对其是否是半导体未做结论。大量的研究已证实了LnN是半导体，而对LnP却未能得出一致结论。本文以La、Nd、Sm、Y为代表研究了稀土磷化物的光学性质、电学性质和热电性质。由实验结果证实了稀土磷化物是N型半导体。稀土磷化物多晶粉末是用元素合成法制备的。合成LnP的最佳条件为：温度：950 ℃-1000 ℃；时间：10 ～ 36小时；真空度：3 * 10~(-5)笔。对制备后的LnP做了X-ray衍射分析，确定了LnP有氯化钠结构。其中，YP没有ASTM卡，我们参照其衍射图计算了它的晶面间距值，得出其晶格常数为a = 5.652A，计算的d_(nkL)值与实验值符合很好。通过实验证实了合成的LnP是单一化合物。在实验中测量了LnP薄膜的吸收光谱并将其与GaAs的吸收光谱做了比较，证实了稀土磷化物是直接跃迁型材料。同时也求出了LnP的禁带宽度值。其中，NdP、LaP、YP的禁带宽度值是首次得到，文献中未见有报导。从La到Y随着晶格常数变小，禁带宽度值亦减小，该实验结果与Sclar用经验式计算的结果是一致的。在实验中还利用热探针、霍尔系数和热电菌率系数测量了LnP的导电类型，结果表明它们是N型半导体。用四探针测量了它们的电阻率为～10~(-3)ncm。并研究了它们的电阻与温度关系，发现LnP具有半导体的重要特征－电阻的负湿度系数。同时，从电阻与温度关系求出了LnP的激活能、该值较小，说明LnP中存在浅施主能级，我们分析是由于磷缺位在LnP形成正电中心而引入的。所测量的LnP的热电功率系数为近百μv/℃。也以热电功率系数与温度的关系求得了LnP的激活能，这与从电阻与湿度关系所得的激活能值是相符的。这证实了我们对LnP存在浅施主能级所做的判断。本文还对上述试验结果做了简要分析讨论。提出了LnP的能带图。我们认为：稀土磷化物是直接跃迁型的N型半导体。

Analysis of sulfur-containing compounds in crude oils by comprehensive two-dimensional gas chromatography with sulfur chemiluminescence detection

This paper reports an analytical method for separating, identifying, and quantifying sulfur-containing compounds in crude oil fraction (IBP-360degreesC) samples based on comprehensive two-dimensional gas chromatography coupled with a sulfur chemiluminescence detector. Various sulfur-containing compounds and their groups were analyzed with one direct injection. 3620 peaks were detected including 1722 thiols/thioethers/ disulfides/1-ring thiophenes, 953 benzothiophenes, 704 dibenzothiophenes, and 241 benzonaphthothiophenes. The target sulfur compounds and their groups were identified based on the group separation feature and structured retention of comprehensive two-dimensional gas chromatography as well as standard substances. The quantitative analysis of major sulfur-containing compounds and total sulfur was based on the linear response of the sulfur chemiluminescence detector using the internal standard method. The sulfur contents of target sulfur compounds and their groups in 4 crude oil fractions were also determined. The recoveries for standard sulfur-containing compounds were in the range of 90-102%. The quantitative result of total sulfur in the Oman crude oil fraction sample was compared with those from ASTM D 4294 standard method (total S by X-ray fluorescence spectrometry), the relative deviation (RD%) was 4.2% and the precision of the method satisfactory.

Determination of sulfur-containing compounds in diesel oils by comprehensive two-dimensional gas chromatography with a sulfur chemiluminescence detector

This article reports an analytical method for separating, identifying and quantitating sulfur-containing compounds and their groups in diesel oils (170-400degreesC) using comprehensive two-dimensional gas chromatography coupled with a sulfur chemiluminescence detector. The identification of target compounds and their groups was based on standard substances, the group separation feature and the-effect of comprehensive two-dimensional gas chromatography. The quantitative analysis on major sulfur compounds and total sulfur was carried out based on the linear response of sulfur chemiluminescence detector and the internal standards method. The results of total sulfur determination in the samples were compared with those from ASTM D 4294 standard method, the R.S.D. percentage were <6.02%, correctness of this method can meet the industrial requirement. To the end, the method developed was used to investigate the sulfur-containing compounds in different diesel oils, the result shows that the distribution of sulfur-containing compounds in diesel oils from different process units are apparently different. The sulfur compounds in fluid catalytic cracking (FCC), residuum fluid catalytic cracking (RFCC) diesel oils mainly exist in the form of alkyl-substituted dibenzothiophenes that add up to about 40-50% of the total sulfur, while this number is only 6-8 and 20-28% in visbreaking (VB) and delayed-coking (DC) diesel oils, respectively. (C) 2003 Elsevier B.V. All rights reserved.

Structure and luminescent properties of YAG : Eu, Bi synthesized by sol-gel method

(Y1-xEux)(3)Al5O12 and (Y1-x-yEuxBiy)(3)Al5O12 were prepared by so-gel method. Their structures of the luminophor are similar to that of YAG, which is recorded on the ASTM card and belongs to a cubic system. The luminescent properties show that the reaction temperature of the current sol-gel method is in the range of 400-500 degrees C, which is lower than that of the conventional solid state reaction. The luminophors have the strongest emission intensity when the values of x and y are 0.06 and 0.013, respectively.

ABF_4: Eu~(2+)和A_2SiF_6: Eu~(2+)中Eu~(2+)的光谱结构

合成了Eu~(2+)激活的ABF_4和A_2SiF_6(A=Na、K、Rb、Cs)复合氟化物磷光体,得到了与ASTM一致的结晶学数据,在这些体系中都观察到了Eu~(2+)的f→跃迁锐峰发射,其中NaBF_4:Eu~(2+)和Na_2SiF_6:Eu~(2-)中Eu~(2+)所处基质晶格的配位数较低。

Luz transmitida y dispersada por materiales para coberturas de invernaderos

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