液压支架电液控制系统技术的发展与现状分析

分析了支架电液控制系统对煤矿生产的重要性,介绍国内外液压支架电液控制系统技术发展概况,电液控制系统的原理和关键技术。分析中国发展支架电液系统技术落后的原因,对国内液压支架电液控制系统发展提出建议。     

复合沙棘原液对高脂血症大鼠的降脂作用

目的:探究复合沙棘原液对高脂血症模型大鼠的降血脂作用的影响。方法:将60只Wistar大鼠随机分为空白对照组、高脂模型组、阳性对照组(洛伐他汀胶囊1.80 mg/kg·bw)、复合沙棘原液低(3.57 mL/kg·bw)、中(7.14 mL/kg·bw)、高(14.28 mL/kg·bw)剂量组,并通过高脂饲料喂养法构建高脂血症大鼠模型。空白对照组和高脂模型组灌胃等量生理盐水,实验组大鼠分别灌胃相应剂量的复合沙棘原液及洛伐他汀混悬液。给药28 d后,观察与分析各组大鼠的体重、Lee’s指数、血清血脂水平、抗氧化水平、肝脏指数及肝脏病理形态。结果:与空白对照组相比,高脂模型组大鼠体重、Lee’s指数均极显著升高(P<0.01),表明模型构建成功;阳性对照组、复合沙棘原液高剂量组与高脂模型组相比血清中总胆固醇(total cholesterol,TC)、甘油三酯(triglyceride,TG)、低密度脂蛋白胆固醇(low-density lipoprotein cholesterol,LDL-C)、丙二醛(malondialdehyde, MDA)含量均降低,高密度脂蛋白胆固醇(h...     

基于响应面法优化高产乙酸乙酯大曲清香型白酒二米查酒醅恒温发酵工艺

以大曲清香型白酒大米查酒糟为发酵底物,二米查酒醅发酵工艺为基础,以酒醅中乙酸乙酯含量及酒精度为考察指标,采用单因素试验及响应面试验对二米查酒醅恒温发酵工艺进行优化。结果表明,最优大曲清香型白酒二米查酒醅恒温发酵工艺条件为大曲添加量12%,辅料添加量8.8%,水分添加量44%,发酵温度28℃,发酵时间21 d。在此优化条件下,二米查酒醅中乙酸乙酯含量最高,为（0.69±0.01）g/kg,比优化前（0.39 g/kg）提高76.9%。     

厚松散层下煤层开采地表沉陷模拟研究

以国内某大型煤矿为原型,采用FLAC3D有限差分软件对厚松散层下,内部煤矿开采过程中地表沉陷进行数值模拟,并对模拟结果进行了分析和探讨.研究表明:随着煤炭资源的采出,地表沉陷不断增大,并且相比于一般条件,厚松散层下煤炭开采所产生的地表沉陷影响范围变大.     

Catalytic activity of Ni–YSZ–CeO2 anode for the steam reforming of methane in a direct internal-reforming solid oxide fuel cell

As one of the key technologies in the development of a direct internal-reforming solid oxide fuel cell, catalytic activity and stability of a Ni–YSZ–CeO₂ anode on a zirconia electrolyte for the steam reforming of methane was investigated by experiments using a differential fuel cell reactor. The effects of the partial pressure of CH₄, H₂O and H₂, and temperature as well as the electrochemical oxidation on the catalytic activity were analyzed. It was found that the catalytic activity of the Ni–YSZ–CeO₂ anode was higher than that of the Ni–YSZ reported especially at low temperature. A deterioration of the catalytic activity of the anode was observed at low P_H2 and high P_H2O atmosphere, and also at high current densities. This might be caused by the oxidation of the Ni surface by H₂O in the reaction gas and that produced by the anodic reaction. A rate equation for a fractional function for the steam reforming on open circuit was also proposed.     

藻蓝蛋白-壳聚糖复合膜的制备及性能表征

以壳聚糖为基材,将藻蓝蛋白添加到壳聚糖膜中制成复合膜,探讨藻蓝蛋白添加配比对复合膜的理化性质、机械性能、及抑菌性的影响。结果表明:随着藻蓝蛋白添加比例增加(0.5%~1.0%,w/v),复合膜的水蒸气透过性与抗拉强度减小,而不透明度、抑菌活性及断裂伸长率增加。当藻蓝蛋白添加比例为1.0%时,复合膜表面、内部结构更均一致密,具有最大的不透明度(3.927 Abs₆₀₀·mm-1)、断裂伸长率(79.73%)和最低的水蒸气透过系数(1.273×10-10g·m-1·s-1·Pa-1)。1.0%复合膜对大肠杆菌的抑菌圈直径最大,为22.36 mm。该研究可为藻蓝蛋白-壳聚糖复合活性膜的应用提供理论依据。     

Equilibrium and spectroscopic studies on the complexation of tris(1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato)lanthanoids(III) with tris(2,4-pentanedionato)cobalt(III) as complex ligand

Complexation equilibrium between tris(1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato)lanthanoids(III) (Ln(tta)₃, Ln=La, Eu, and Lu) and tris(2,4-pentanedionato)cobalt(III) (Co(acac)₃) has been studied by the liquid–liquid distribution technique. A 1:1 adduct of [Ln(tta)₃Co(acac)₃], i.e., a binuclear complex, was formed in benzene, and the stability constants were determined to be 10^4.64, 10^2.95, and 10^2.07 for La, Eu, and Lu respectively. The molar absorptivity of Co(acac)₃ for the ¹T_1g←¹A_1g transition increased with the adduct formation with Ln(tta)₃ in the order of Lu≪Eu<La. A ⁵⁹Co NMR study showed that a resonance of Co(acac)₃ shifted to the higher field with the adduct formation. The chemical exchange between free and complexed Co(acac)₃ was very slow in La but fast in Lu, while both the slow- and fast-exchange species existed in Eu.     

Nickel-doped cobalt molybdate nanorods with excellent cycle stability for aqueous asymmetric supercapacitor

Herein, nickel-doped cobalt molybdate (Ni_xCo_1-xMoO₄, x = 0, 0.1, 0.3, 0.4, 0.5, 0.6) with nanorods structure are successfully prepared through a facile co-precipitation approach. The molar ratio of nickel and cobalt would affect the morphologies. The Ni_0.5Co_0.5MoO₄ electrode exhibits satisfactory specific capacity and rate performance (325.9 C/g at 0.5 A/g, 260 C/g at 10 A/g). Moreover, the asymmetric supercapacitor (ASC) device is assembled using Ni_0.5Co_0.5MoO₄ and carbon spheres as positive and negative electrodes, respectively. The ASC device possesses high energy density of 31.57 Wh/kg at the power density of 400 W/kg, and even maintains high energy density of 13.56 Wh/kg at the power density of 8000 W/kg. Meantime, the ASC device possesses excellent capacitance retention rate and coulomb efficiency after 5000 charge-discharge cycles. And a red light-emitted diode is illumed using two ASC devices in series.     

Methane release from actively yielding coal and its implications for yield zone determination

One measure of the capacity of coal pillars to support load is the proportion of material in them which can be classified as “yielded”. As a means of determining the extent of yielded material in a pillar, the relation between methane emission and yielding has been investigated through laboratory testing at the Denver Research Center, U.S. Bureau of Mines. Sample yielding, as defined by drops in axial load during uniaxial compression, was monitored coincident with methane concentration, axial deformation, acoustic emission, temperature and gas pressure. While acoustic emission gave an ambiguous measure of yielding, methane release correlated with significant drops in load. No increases in methane concentration were observed before yielding, so increases in methane emission may be correlated with structural yielding of the sample. A large permanent increase in concentration observed at final yielding indicates that a major proportion of gas is in the micropore and unconnected crack system of the coal. Thus, the release of this bound-up portion of gas provides a proportional measure of the degree of structural damage experienced by the coal.     

Grain-orientation-engineered multilayer NaSr2Nb5O15 ferroelectric ceramics via templated grain growth

It is difficult to take both texture degree and density into account by the conventional method, especially when one-dimensional particles are used as templates to prepare textured ferroelectric ceramics. Here, we proposed a strategy to improve the texture degree and density of ceramics simultaneously by a grain-orientation-engineered technique. To solve the problem of directional arrangement of template particles, template layers without mixed matrix were prepared by the brushing technique. Dense textured NaSr₂Nb₅O₁₅ ceramics with grain size gradient distribution were designed by the lamination of template and matrix layers. An evaluation method of texture degree was developed. Ferroelastic and ferroelectric domains were observed simultaneously in the oriented grains, which was further confirmed that the ferroelectric-ferroelastic phase transition occurred for the NaSr₂Nb₅O₁₅ ceramics at the low temperature. The obtained textured NaSr₂Nb₅O₁₅ ceramics exhibited the high piezoelectric constant (d₃₃ =134 pC/N). The present research offers a route for designing grain-oriented ferroelectric ceramics.