Synthesis of mesoporous silica (SBA-16) nanoparticles using silica extracted from stem cane ash and its application in electrocatalytic oxidation of methanol

In this work, a new catalyst based on modified mesoporous silica SBA-16 is proposed and used for electrochemical oxidation of methanol. Mesoporous silica SBA-16 nanoparticles are synthesized hydrothermally under the acidic medium using SiO₂/F127/BuOH/HCl/H₂O gel. Pure SiO₂ powder is prepared from inexpensive and environmentally friendly silica source of stem cane ash (SCA). The synthesized SBA-16 is characterized using X-ray diffraction, scanning electronic microscopy, transmission electron microscopy, Brumauer–Emmett–Teller (BET) and FT-IR techniques. The synthesized SBA-16 is modified with Ni(II) by dispersion in a 0.1 M nickel chloride solution. A modified carbon paste electrode (CPE) is prepared by mixing of NiSBA-16 to carbon paste (NiSBA-16CPE). The electrocatalytic oxidation of methanol was studied on modified electrode by cyclic voltammetry and chronoamperometry. From cyclic voltammetry, it is observed that the oxidation current is extremely increased by using NiSBA-16CPE compared to the nonmodified CPE. The incorporation of Ni²⁺ into SBA-16 channels provides the active sites for catalysis of methanol oxidation. Also, the rate constant for the catalytic reaction (k) of methanol is obtained.     

烧结温度对Ni16Cr9Al多孔材料性能的影响

以粒度小于25 μm的Ni16Cr9Al预合金粉末为原料,采用模压成形、真空烧结的方法制备了Ni16Cr9Al多孔材料,研究了烧结温度对Ni16Cr9Al多孔材料性能的影响。结果表明：Ni16Cr9Al粉末压坯在烧结过程中由于烧结颈的形成、长大,体积发生收缩,随着温度的升高,烧结体的孔隙度和孔径减小,强度提高,1130 ℃具有良好的三维孔隙结构,高于1150 ℃,孔隙减少,材料逐渐致密     

嗜酸兼性异养菌Acidiphilium sp.DX1-1的分离、特征及其浸矿行为(英文)

研究了一株源自江西德兴铜矿矿区的中温嗜酸兼性异养菌Acidiphilium sp.DX1-1的分离、鉴定、特征及其浸矿行为。菌株Acidiphilium sp.DX1-1为短杆状革兰氏阴性菌,最适合的生长温度为30℃,最适合的生长pH约为3.5。该菌株具有广泛的底物利用特性,可以利用有机物进行异养生长并在细胞内积累聚羟基丁酸酯,也可以利用单质硫、三价铁等无机物进行自养生长。系统发育分析表明DX1-1属于Acidiphilium属,与Acidiphilium cryptum and Acidiphilium multivorum的同源性大于99%。在铁闪锌矿生物浸出过程中,Acidiphilium sp.DX1-1表现出极强的浸矿能力,其作用不仅仅是之前报道的作为其他自养嗜酸浸矿细菌的辅助者。在初始pH3.5时,DX1-1能够在一个月内单独地浸出铁闪锌矿中40%的锌。该浸出率高于它与A.ferrooxidans混合以及A.ferrooxidans单独浸出铁闪锌矿(初始pH均为2.0)的浸出率。     

微生物法净化烟气中NO的机理

为搞清微生物法净化烟气中NO的机理,采集脱氮塔生物膜高效功能菌群样品,建立 16S rRNA基因、nxrA功能基因各自相应的克隆文库,研究脱氮塔脱氮效率最高时微生物的群落结构及功能特征。结果表明：具有反硝化作用的异养菌较具有硝化作用的自养菌在数量和种类上均占绝对优势,但其在功能上却达到了一定程度的动态平衡,出现循环液中NO -3浓度范围基本稳定的状态。反硝化菌造成了体系中的N素损失,使循环液中NO -3不被大量累积。硝化杆菌属的Nitrobactor winogradskyi与Nitrobacter alkalicus等细菌发生了将NO氧化为NO -2,NO -3的硝化作用;变形菌门β亚群（Betaproteobacteria）、变形菌门γ亚群（Gammaproteobacteria）、厚壁菌门（Firmicutes）等微生物发生了将NO -2,NO -3还原为N2或N2O的反硝化作用。     

无线传感网络在瓦斯智能监控系统的应用

从我国煤矿安全生产情况出发,提出了利用Zigbee技术来构建无线传感器网络。在矿井的底部安装许多无线传感器节点,使这些节点分布在矿井的各个角落而且彼此很密集,这些节点就好像构成了一张网,可以检测到矿井下的各个角落的信息,实现煤矿瓦斯的无线监测。主要从节点的硬件设计方案和软件流程图2个方面来做介绍。     

Characterization and catalytic properties of mesoporous CuO/SBA-16 prepared by different impregnation methods

CuO/SBA-16 catalysts were prepared by two different routes - the conventional impregnation method and the modified impregnation method with pH adjustment. These catalysts were characterized by X-ray diffraction (XRD), atomic absorption spectrometry (AAS), N₂ physisorption and hydrogen temperature programmed reduction (H₂-TPR) measurements which reveal that the cubic cagelike (Im3m) pore structure of the parent SBA-16 molecule sieves was well maintained throughout the synthesis. After introduction of Cu, a different CuO dispersion exists on these catalysts. The CuO/SBA-16 prepared by modified impregnation method has a single highly dispersed CuO which is considered as a highly efficient species for hydroxylation of phenol with H₂O₂. CuO/SBA-16 prepared by the conventional impregnation method shows the presence of bulk CuO species which is undesirable for this reaction.     

基于AVR单片机的液晶显示系统的设计

液晶作为当前常用的仪器仪表显示器件之一,通常采用MCS-51单片机进行驱动,存在外围接口电路相对复杂的特点.本文实现了一种以AVR系列单片机为显示控制芯片,以FMl2232为液晶显示器的应用系统.其电路相对简单,同时具有较强的二次开发能力,能够应用于很多需要液晶显示场合.     

Theoretical and experimental study on hydrodynamic characteristics of fluidization in air-sand conical beds

This work was aimed at modeling hydrodynamic characteristics of fluidization in conical beds using quartz sand as the inert bed material and air as the fluidizing agent. The minimum fluidization velocity, u_mf, and the minimum velocity of full fluidization, u_mff, were determined by Peng and Fan's models modified for conical fluidized bed. Meanwhile, the pressure drop across a bed, Δp (including Δp_max and Δp_mff corresponding to u_mf and u_mff, respectively), was predicted by using modified Ergun's equations for variable superficial air velocity at an air distributor, u₀. The predicted results were validated by experimental data for some operating conditions. Effects of the sand particle size, cone angle and static bed height on the fluidization pattern and hydrodynamic characteristics are discussed. With the proposed models, the Δp-u₀ diagram were obtained with rather high accuracy for the conical air-sand beds of 30-45^° cone angles and 20-30 cm static bed heights, when using 300- sand particles. For the predicted u_mf and u_mff, the relative computational errors were found to be within 20% for wide ranges of operating variables, whereas Δp_max and Δp_mff could be predicted with lower (10-15%) relative errors. With higher cone angles and/or bed heights, the computational accuracy was found to deteriorate.     

Formation and behavior of composite CO2 hydrate particles in a high-pressure water tunnel facility

Sinking CO₂ composite particles consisting of seawater, liquid CO₂, and CO₂ hydrate were produced by a coaxial flow injector fed with liquid CO₂ and artificial seawater. The particles were injected into a high-pressure water tunnel facility to permit determination of their settling velocities and dissolution rates. Injections were performed at fixed pressures approximately equivalent to 1200-m, 1500-m, and 1800-m depths and at temperatures varying from approximately 2 to 5 °C. Immediately after injection, the cylindrical particles were observed to break away from the injector tip and often aggregated into sinking clusters. The seawater flow in the tunnel was then adjusted in a countercurrent flow mode to suspend the particles in an observation window so that images of the particles could be recorded for later analysis. The flow would often break or cause rearrangement of some of the clusters. Selected individual particles and some clusters were studied until they became too hydrodynamically unstable to follow. In general, the flow required to suspend clusters or individual particles decreased with time as the particles dissolved. For example, one particle was produced and observed for over 6 min at an average pressure of 15.022 MPa and an average temperature of 5.1 °C. Its sinking rate, determined from the flow required for stabilization, changed from 37.2 to 3.3 mm/s over this time. Particle sinking rates were compared to correlations from the literature for uniform cylindrical objects. Reasonable agreement was observed for short times; however, the observed decrease in sinking velocity with time was greater than that predicted by the correlations for longer times. Particle dissolution rates, based on changes in diameter, were also determined and varied from 5 to . A pseudo-homogeneous mass transfer model was used to predict single-particle dissolution rates. Good agreement was achieved between experimental dissolution data and the modeling results.     

15MnVR与16MnR钢在氢氧化钠溶液中的抗应力腐蚀试验研究

采用楔形张开加载（WOL）恒位移预裂纹试样研究了16MnR钢和15MnVR钢在氢氧化钠溶液中的抗应力腐蚀性能。测得了180℃下30％NaOH溶液中两种材料的应力腐蚀临界应力强度因子和裂纹扩展速率,即16MnR材料的应力府蚀裂纹扩展速率da／dt为0．039～0．040mm／h,KISCC不大于82．75～90．85MPa·m^0.5,15MnVR材料的应力腐蚀裂纹扩展速率da／dt为0．018mm／h,KM。不大于87．58～102．44MPa·m^0.5。同时采用扫描电镜和能谱技术对断口进行了相应的观察和理论分析,得出NaOH溶液中两种材料均为沿晶开裂。