Photocatalytic H2 production from acetic acid solution over CuO/SnO2 nanocomposites under UV irradiation

The CuO/SnO₂ composites have been prepared by the simple co-precipitation method and further characterized by the XRD, FESEM and Raman spectroscopy. The photocatalytic H₂ production from acetic acid (HAc) solution over CuO/SnO₂ photocatalyst has been investigated at room temperature under UV irradiation. Effects of CuO loading, photocatalyst concentration, acetic acid concentration and pH on H₂ production have been systematically studied. Compared with pure SnO₂, the 33.3 mol%CuO/SnO₂ composite exhibited approximately twentyfold enhancement of H₂ production. The H₂ yield is about 0.66 mol-H₂/mol-HAc obtained under irradiation for prolonged time. The Langmuir-type model is applied to study the dependence of hydrogen production rate on HAc concentration. A possible mechanism for photocatalytic degradation of acetic acid over CuO/SnO₂ photocatalyst is proposed as well. Our results provide a method for pollutants removal with simultaneous hydrogen generation. Due to simple preparation, high H₂ production activity and low cost, the CuO/SnO₂ photocatalyst will find wide application in the coming future of hydrogen economy.     

Research on GA-BP neural network model of surface roughness in air drum sanding process for poplar

Roughness is an important property of wood surface and has a significant influence on the interface bonding strength and surface coating quality. At present, there is little research on theoretical models for poplar fine sanding. In this study, poplar wood was fine-sanded with an air drum. An orthogonal experiment was carried out to study the effects of abrasive grain size, feed rate, belt speed, air drum deformation and air drum pressure on the surface roughness of poplar wood. The simulation models of the longitudinal roughness and the lateral roughness of the sanding surface were established based on BP neural network optimized by genetic algorithm (GA-BP neural network), and verified by the experimental data. The results show that the influence of sanding parameters on longitudinal roughness and lateral roughness is similar. The order of influence is abrasive grain size?>?belt speed?>?feed speed?>?air drum deformation and air drum pressure. The longitudinal roughness and lateral roughness of the surface of the poplar can be well predicted by GA-BP neural network. The average relative error of the predicted longitudinal roughness and lateral roughness are 2.67% and 2.65%, respectively.

     

长临界组合通路的重构算法

讨论了组合电路中长临界组合通路的重构变换算法,并证明了该算法的正确性及时地优化的有效性。     

起爆药包形状对多孔粒状铵油炸药猛度测试的影响

《炸药猛度试验铅柱压缩法》（GB/T 12440-1990）关于多孔粒状铵油炸药猛度r 测试,仅提及使用5 g起爆药包,并未规定起爆药包的形状。为分析起爆药包形状对多孔粒状铵油炸药猛度测试的影响,采用5种不同形状的起爆药包（即球形药包、圆柱形药包、圆锥形药包、圆台形药包和倒圆台形药包）,通过铅柱压缩法测试了多孔粒状铵油炸药的猛度。结果表明：药包形状对猛度测试结果影响较大,采用圆锥形药包测得的猛度值最大,且偏差较大;采用球形药包测得的猛度值离散程度最小,数据最稳定可靠。     

Highly Efficient Pd/Tetraphosphine Catalytic System for Copper-Free Sonogashira Reactions of Aryl Bromides with Terminal Alkynes

Abstract  

In this study, an easily synthesized polydentate ligand N,N,N’,N’-tetra(diphenylphosphinomethyl)-1,2-ethylenediamine (1) in combination with [Pd(C₃H₅)Cl]₂ was found to be an active catalyst in copper-free Sonogashira reactions. Most substrates, including steric hindered phenyl bromides and heteroaryl bromides, could couple efficiently with terminal alkynes in the presence of low catalyst loading (0.1 mol%) and this catalytic system showed excellent functional group tolerance. The influence of water in this system was also preliminarily investigated via ³¹P NMR in situ; that is, appropriate water favors the reaction while excess hindered this reaction.     

真空干燥动力学实验平台的设计及测试

真空干燥既能保证干燥后物料品质, 又能提高干燥速率, 且具有干燥温度低, 温差热应力小和适用于热敏性物料干燥等优点。相对于传统热风干燥, 作为热敏性作物的稻谷采用真空干燥可以有效降低爆腰率和提高发芽率。为研究稻谷真空干燥动力学特性, 设计搭建了可准确控制相对压力、温度并实时测量质量的干燥动力学实验平台。该平台包括真空控制模块、温度控制模块、质量称量模块、实时数据采集与控制模块以及数据处理模块。对实验平台的真空控制、温度控制和质量测量性能进行测试分析, 结果表明该平台能够实现相对压力和温度的准确控制并实现干燥数据的实时精确采集。     

SDS-6500R高频超声C扫描水浸探伤技术及应用

介绍了超声波图像可视装置SDS-6500R,及其对缺陷的定性判断原理和定量分析方法。利用该设备,对炼钢厂生产的连铸坯样品（截面为20mm×20mm）进行了超声C扫描探伤,并通过金相显微镜观察对探伤结果进行验证。结果表明,使用50MHz的高频水浸聚焦探头,该设备可以有效探测被检测件中〉30μm的非金属夹杂物等缺陷,将夹杂物和气孔区分开来,而且对缺陷数量的统计结果也比较精确,适用于实验室检测和分析。     

蝎毒组分Ⅲ对人头颈部鳞状细胞癌细胞生长的影响

目的 观察蝎毒组分Ⅲ(SVC-Ⅲ)对人头颈部鳞状细胞癌细胞株(AGZY-973)生长的影响,试图找出SVC Ⅲ抑制鳞状细胞癌的最佳浓度。方法 采用噻唑蓝(MTT)法检测经不同浓度SVC-Ⅲ 作用下AGZY-973 生长抑制率。结果 SVC Ⅲ能抑制该细胞的生长,SVC-Ⅲ可导致AGZY-973 细胞代谢MTT 的能力显著低于对照组,生长抑制率达68.96%(P <0.01)。当SVC Ⅲ的浓度<40 mg·L^-1时,剂量效应关系明显;而SVC-Ⅲ的浓度>40 mg·L^-1时无剂量效应关系。5-Fu 治疗组生长抑制率达55.27% P <0.01)。结论 SVC-Ⅲ是存在于东亚钳蝎蝎毒中的一种抗肿瘤成分,能够抑制AGZY-973 的生长,并在一定浓度范围内存在剂量效应关系。     

Determining optimum conditions for hydrogen production from glucose by an anaerobic culture using response surface methodology (RSM)

Hydrogen fermentation is a very complex process and is greatly influenced by many factors. Previous studies have demonstrated that temperature, pH and substrate are important factors controlling biological H₂ production. Response surface methodology with central composite design was used in this study to optimize H₂ production from glucose by an anaerobic culture. The individual and interactive effects of pH, temperature and glucose concentration on H₂ production were also evaluated. The optimum conditions for maximum H₂ yield of 1.75 mol-H₂ mol-glucose⁻¹ were found as temperature 38.8 °C, pH 5.7 and glucose concentration 9.7 g L⁻¹. The linear effects of temperature and pH as well as their quadratic effects on H₂ yield were significant, while the interactive effects of three parameters were minor.     

无机胶粘岩土的抗渗性能研究

首先介绍了渗透性评价指标的测定方法．通过对4组试块(24个试样)进行pH值测试、金属元素含量的测定，得出了岩土的pH值小于7，显酸性，对提高抗渗性能作用较大，岩土的金属元素含量对抗渗性能影响不大；又进行了抗渗试验，得出了渗透系数与抗渗标号的关系，氟硅酸钠对抗渗性能影响较大；并进行X射线衍射的成分分析，对岩土的渗透性能进行剖析。