Kinetic study on the metallothermic reduction of chromite ore using magnesium scrap

A study on the metallothermic reduction of chromite ore is presented and discussed, using magnesium scrap as reducing agent. Microstructural analysis corroborated the distribution of phases inside the particles, where Fe and Cr were located at the centre surrounded by layers of reaction products, mainly MgO. The maximum conversion efficiency of Fe and Cr was 38% at 1050°C, after a reaction time of 3 hours, using 75% excess of magnesium scrap. A kinetic study was performed fitting the experimental data to available kinetic models, where the data adjusted to the chemical reaction model, especially at the beginning of reaction. A second reaction stage was confirmed once the experimental data was adjusted to the Jander diffusion model. For the chemical reaction model, the constant rate and the activation energy were 0.32?h^?1 and 60.12?kJ?mol^?1, respectively. For the diffusion model, the rate constant was 0.20?h^?1 and the activation energy 47.04?kJ?mol^?1.     

Thermal kinetics investigation on light oil oxidation during high-pressure hypoxic air injection process

In this work, the effects of oxygen concentration and reservoir cutting on thermokinetic characteristics of light oil were analyzed using thermogravimetry (TG/DTG). Results show that three consecutive oxidation reactions of distinct chemical mechanism (low-temperature oxidation [LTO], fuel deposition [FD], and high-temperature oxidation) are detected for all tested samples. Hypoxic air weakens the LTO and FD process and causes a poor FD performance, while reservoir cutting positively influences the thermal characteristics of oil. Kinetic parameters comparison exhibits that the positive effect of reservoir cutting on oil oxidation is significantly stronger than the negative impact caused by hypoxic air. The existence of reservoir cutting greatly reduces the activation energy of oil oxidation in hypoxic air environment, which is a positive signal for the implementation of high-pressure hypoxic air injection process.     

Optimisation of the extraction conditions of natural colourant carthamin from safflower (Carthamus tinctorius L.) by response surface methodology

Alkali‐solution and acid‐isolation method (ASAI) and aqueous two‐phase system separation method (ATSS) have been reported to extract natural colourant carthamin from Carthamus tinctorius. In this study, these two methods were compared based on the optimisation results of extraction conditions by response surface methodology. In ASAI, the maximum extraction yield reached 0.779% at pH value of potassium carbonate solution of 11.16, ratio of potassium carbonate solution to raw material of fifteen and extraction time of 18 min, while 2.652% was achieved with concentration of acetone of 58%, ratio of acetone solution to raw material of twenty‐three and extraction time of 41 min in ATSS. From the point of view of extraction yield, ATSS had more superiority than ASAI. However, more pure carthamin was provided in ASAI according to HPLC assay. The obtained results in our experiments could be utilised for further researches of carthamin.     

透层油、粘层油在沥青混凝土路面中的作用

对透层油和粘层油的作用机理进行了分析,阐明了其在路面结构中的作用,详细介绍了透层粘层的施工工艺,并提出了在施工过程中的注意事项。     

A two-pronged approach for springback variability assessment using sparse polynomial chaos expansion and multi-level simulations

In this study, we show that stochastic analysis of metal forming process requires both a high precision and low cost numerical models in order to take into account very small perturbations on inputs (physical as well as process parameters) and to allow for numerous repeated analysis in a reasonable time. To this end, an original semi-analytical model dedicated to plain strain deep drawing based on a Bending-Under-Tension numerical model (B-U-T model) is used to accurately predict the influence of small random perturbations around a nominal solution estimated with a full scale Finite Element Model (FEM). We introduce a custom sparse variant of the Polynomial Chaos Expansion (PCE) to model the propagation of uncertainties through this model at low computational cost. Next, we apply this methodology to the deep drawing process of U-shaped metal sheet considering up to 8 random variables.     

ZZ9900/29.5/50型支架护帮装置限压阀板的改进

对ZZ9900/29.5/50型支撑掩护式大采高液压支架护帮装置限压控制系统限压阀板存在的缺陷进行了分析、改进.     

A near-infrared dye for dye-sensitized solar cell: Catecholate-functionalized zinc phthalocyanine

The design and synthesis of an asymmetrical zinc phthalocyanine sensitizer modified with a catechol anchoring group is reported. The performance of this sensitizer was evaluated in a dye-sensitized solar cell. A strong interaction between the catechol dye and TiO₂ (with the formation of a five-membered charge-transfer complex) was evidenced by a strong shift in the Q-band of the ZnPc-Cat from 680 nm in solution to 750 nm on TiO₂, along with an appreciable absorption tail extending to ∼1000 nm. The fabricated solar cell containing the phthalocyanine sensitizer showed relatively high light-to-electron conversion efficiency (η = 0.92%), considering that few catechol dyes exceed η = 0.7% in dye-sensitized solar cells. Values of I_sc = 2.53 mA cm⁻² and V_oc = 540 mV were obtained, referring to a standard N719 cell (η = 6.46%). A comparison of zinc phthalocyanine sensitizers bearing different anchoring groups affirmed the superiority of carboxylate groups relative to those bearing catechol groups in terms of cell performance.     

农药作为海洋防污剂的应用

纵观海洋防污剂发展史，我们可以发现它和农药之间有着不解之缘，也可以说农药的发展推动了防污剂的发展。文章对曾经用过、正在使用、有可能应用为海洋防污剂的农药品种逐一介绍。     

X-RAY镀层测厚仪检测及校正方法浅析

基于X-RAY荧光光谱方法的基础理论,简单分析了能量散射X-RAY荧光光谱分析法的工作原理,通过对准直器尺寸、测量时间、应用程式、基材等参数的选择,分析了X-RAY镀层测厚仪检测及校正的方法。结果表明,检测校正后的X-RAY镀层测厚仪,测量结果的相对误差、相对标准差小,且该方法对企业生产具有指导意义。