Microwave-assisted green synthesis of MnO2 nanoplates with environmental catalytic activity

In this paper, MnO₂ nanoplates were synthesized in aqueous solution under the microwave irradiation, without using any templates, catalysts, and organic reagents. The as-prepared MnO₂ nanoplates were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), high-resolution TEM (HRTEM), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and thermo-gravimetric (TG) analysis, and nitrogen sorption measurements. Microwave irradiation could produce MnO₂ with uniform size and well-defined shape as well as high crystallinity. On the basis of experimental results, a possible formation mechanism of MnO₂ nanoplates was proposed. Furthermore, the resulting MnO₂ nanoplates were found to exhibit remarkable environmental catalytic performance in degradation of Rhodamine B (RhB) in aqueous solution, indicating these MnO₂ nanoplates is very promising for wastewater treatment.     

南港渡槽4~#墩基悬空原因简析与加固措施

文章对南港渡槽4#墩基础悬空的原因作简要分析,提出加固方案,并对施工中的技术要点和措施进行阐述。     

Numerical and experimental investigation of preform design in non-axisymmetric warm forming

This paper describes a numerical and experimental investigation of preform design in non-axisymmetric warm forming in order to achieve a large reduction in the volume of flash. A titanium TA2 watch-case-like component was used as an example. Sixteen different shapes of hollow preforms were specially designed for finite-element simulation. Their diameters of the center-holes were designed based on the values of the diameters of end-face configurations of punches and ejectors. The corresponding thicknesses of the preforms were determined by the assumption of constant volume. Under the same processing conditions, the diameter of center-hole of the preform should be the inner diameter of ejector such that its volume of flash was able to be greatly reduced to 6% of the volume of the formed component whereas the volume of flash was approximately 25% in the conventional implementation. Experiments were subsequently performed to verify the simulation results. This study rationally demonstrates the success of the preform design for warm forming of non-axisymmetric components, and provides great improvement in the utilization of material in the bulk forming process. Thus, the achievement is a tremendous saving in materials, more than a fourfold, particularly for these rare and expensive alloys.     

发酵乳杆菌(Lactobacillus fermentum)YB5生理特征的研究

为了开发优良的益生菌菌株,对分离自酸奶的发酵乳杆菌(Lactobacillus fermentum)YB5的生理特性进行了系统研究。耐渗透压试验结果表明,发酵乳杆菌YB5具有一定的耐渗透压能力,其在4%NaCl溶液中生长正常,而在6%NaCl溶液中生长受到抑制;耐酸性试验结果表明发酵乳杆菌YB5具有较强的耐酸性,能够在pH值2.5的培养基中生长;双层平板法抑菌试验结果表明,发酵乳杆菌YB5能产生抑菌物质,该物质对革兰氏阳性菌有明显的抑制作用;YB5抑菌活性具有较强的热稳定性,经40℃或60℃热处理后,其抑菌活性增强;YB5抑菌活性耐酸性,在弱酸和中性环境中其活性降低或丧失。淀粉酶活力检测结果表明,发酵乳杆菌YB5在生长过程中能产生淀粉酶。YB5的这些特性预示着其在食品加工中具有很好的应用潜力。     

粘接剂在恢复热轧主轧机机架设计精度上的应用

在冶金机械设备中,由于特殊的工作环境,主轧机机架磨损非常严重,其精度很难保证,而采用机械加工的方法处理难度较大.本文介绍一种采用修补剂对主轧机机架进行修补恢复主轧机机架设计精度的方法,为解决相似问题提供了一种新的方法和思路.     

近年废胶粉改性道路沥青的研究

介绍了近年道路沥青方面的肢粉研究情况。主要有：胶粉的添加及工艺条件变化对沥青性能的影响，肢粉与沥青的相容性，肢粉改性沥青老化以及改性机理等国内外研究现状及其简要评论。     

宣钢锅炉备煤系统的自动控制

介绍了宣钢动力厂锅炉备煤自动化控制系统的确定、总体方案的设计、具体实施、安装调试及运行效果。     

近地表速度变化对地震波传播的影响

地表起伏和近地表速度变化是影响地震波传播的两个重要因素。采用基于坐标变换的起伏地表弹性波正演模拟方法，对纵向变速、横向变速、随机变速等一系列速度模型进行了正演数值模拟，分析了起伏地表情况下近地表速度的不同变化对正演模拟记录的影响，得出近地表变速带厚度较薄、纵向层状变速明显、横向块状变速剧烈以及介质速度随机变化较大时都会导致噪声严重、模拟记录信噪比变低的结论。