负载型贵金属纳米粒子作为光/超声催化剂在化学合成和降解污染物方面的应用

综述了Au/TiO2、Au/ZrO2、Ag/AgCl等负载型贵金属纳米粒子作为有效的光/超声催化剂在化学合成和降解污染物方面的应用.负载型贵金属纳米粒子能够有效地将太阳能转化为化学能.在紫外光或可见光的辐照下,负载型贵金属纳米粒子能够催化一系列的选择性化学转化,如醇类化合物氧化为醛/酮类化合物、硫醇氧化为二硫化合物、苯氧化为苯酚、硝基苯类化合物还原为偶氮化合物等.在超声波辐射下,负载型贵金属纳米粒子能够有效地催化分解水产氢.此外,在紫外光或可见光的辐照下,负载型贵金属纳米粒子能够有效地催化降解多种污染物,如醛类、醇类、酸类、酚类化合物和染料等.在超声波辐射下,负载型贵金属纳米粒子也能够有效地催化降解包括染料在内的有机污染物.     

反相高效液相色谱法测定肾复康胶囊中的野黄芩苷和芦丁

建立了肾复康胶囊中野黄芩苷和芦丁的反相高效液相色谱测定方法。以甲醇-水为提取溶剂,采用超声提取法对样品进行前处理。以0.02 mol/L磷酸二氢钾缓冲溶液(含1.0％（体积分数）冰醋酸)-甲醇（体积比为63∶37）为流动相,于330 nm波长下检测,肾复康提取液中野黄芩苷和芦丁可达基线分离,分析时间在20 min内。野黄芩苷和芦丁在10 ~300 mg/L内,其峰面积与浓度之间线性关系良好,目标物的加标回收率大于98％。该方法适用于肾复康胶囊及相关药材中野黄芩苷和芦丁黄酮类化合物的测定和质量控制。     

中英高中物理教材中关于电场内容的比较

针对学生在电场学习中的障碍,借鉴和比较中英两国在电场内容上的不同处理,从教学实践和教材编写方面提出意见.     

Deposition Behavior and Mechanism of Ni Nanoparticles on Surface of SiC Particles in Solution Systems

Ni-deposited SiC particles are prepared successfully by a facile chemical reaction approach. The structure and morphology analyses demonstrate the Ni nanoparticles have been deposited on the surface of SiC particles. The deposition behavior of Ni on the surface of SiC particles is investigated. Pd-Sn catalytic nuclei formed in the pretreatment process promote the redox reaction and lead to the reduction of Ni^2＋ to metal nickel. Moreover, the kinetic mechanism of the reaction process of Ni%2＋ and H2PO^-2 has also been discussed in detail. Kinetic models have been established.     

某火车站售票厅吸声降噪

铁路车站售票厅功能日趋多样化,因其客流量大、嘈杂,声环境有待改善.测试了某售票厅内的噪声,确定其主要噪声源,针对测试结果,提出了吸声降噪方案,建立售票厅降噪前后的声场仿真模型,计算了售票厅的吸声降噪量.研究表明,售票厅内平均声压级为74.2 dB(A),主要噪声源是售票员与顾客交流时由扬声器发出的声音.综合考虑降噪量和混响时间,吸水性海绵降噪效果较佳.采用吸水海绵降噪时,室内平均降噪量为5.4 dB,降噪后售票厅内平均声压级为68.8 dB(A),混响时间为1.2～1.3 s,声压级达到限值要求,混响时间符合最佳混响时间要求.     

Microwave Absorbing Materials： Solutions for Real Functions under Ideal Conditions of Microwave Absorption

We present general equations for metal-substrate single-layer microwave absorbing materials. The optimum electromagnetic parameters and matching thicknesses for electric-loss, magnetic-loss, and electromagnetic-loss materials are given, and possible solutions for the equations and the corresponding theoretic curves are discussed as well. The results may be helpful for designing high-performance microwave absorbing materials.     

杯［4］吡咯涂敷C18反相色谱柱分离阴离子及酚类化合物杯吡咯涂敷的HPLC固定相的初步研究

用meso-八甲基杯［4］吡咯静态涂敷MN-C18填料,制备了一种新型大环化合物涂敷固定相。以去离子水作为流动相,考察了有机阴离子(邻苯二甲酸氢根、水杨酸根、苯甲酸根离子)及酚类化合物(间苯三酚、对苯二酚、间氨基酚、间苯二酚、邻苯二酚、苯酚)的色谱分离。与未涂敷柱相比,新型涂敷固定相成功地实现了对3种阴离子的基线分离;对酚类化合物的保留显著增加,同时提高了分离度(尤其是间氨基酚与间苯二酚、间苯三酚与对苯二酚两对峰)。这可归因于杯吡咯与被分析物间存在的氢键相互作用,初步的实验结果也表明杯吡咯对阴离子及中性客     

肝生素治疗40例重型乙型病毒性肝炎的疗效初探

应用肝生素治疗各种重型乙型病毒性肝炎,结果表明,４０例重型乙型病毒肝炎患者经肝生素治疗,治疗组死亡１５例,病死率３７．５％,对照组死亡２６例,病死率６５．０％,两组比较有显著差异。肝生素在重型肝炎的早中期治疗效果特别理想,可认为肝生素是目前治疗重型病毒性肝炎比较理想的护肝药物。     

顶管隧道上穿既有地铁隧道影响机制

为了研究顶管隧道上穿既有地铁隧道施工对既有隧道及周围土体的影响,以电缆隧道上跨西安地铁5号线为研究背景,基于自主设计室内顶管顶进试验装置,采用模型试验和有限元数值模拟相结合的方法研究顶管隧道上跨既有地铁隧道影响机制。试验主要对地表位移、既有隧道应变和既有隧道上方的土压力进行分析,并通过数值模拟对模型试验进行补充研究和对比验证。研究结果表明：地表位移与顶管隧道的埋置深度成反比,当新建隧道埋深小于1.5D(D为隧道直径)时,埋深对地表位移影响较大;顶管轴线两侧土体变化趋势基本对称,与顶管轴线距离越大,土体变形量越小;顶管隧道施工对既有隧道引起位移变化的影响主要集中在顶管正交于既有隧道的位置,既有隧道随着顶管隧道的顶进,逐渐呈隆起状态,并且隧道的拱腰位置隆起要早于拱顶;隧道拱顶纵向最大附加应变均发生在隧道中部即对称面位置,且离顶管隧道轴线越近,附加应变变化也越大;附加应变的变化与夹土层厚度成反比;因试验中有多种客观因素的影响,数值模拟和模型试验的结果虽在数值上有一定差异,但变化规律存在着一致性,由此进一步验证了模型试验结论的可靠性。     

Carbon materials with quasi-graphene layers: the dielectric, percolation properties and the electronic transport mechanism

We investigate the dielectric properties of multi-walled carbon nanotubes (MWCNTs) and graphite filling in SiO₂ with the filling concentration of 2-20 wt.% in the frequency range of 10²-10⁷ Hz. MWCNTs and graphite have general electrical properties and percolation phenomena owing to their quasi-structure made up of graphene layers. Both permittivity ε and conductivity σ exhibit jumps around the percolation threshold. Variations of dielectric properties of the composites are in agreement with the percolation theory. All the percolation phenomena are determined by hopping and migrating electrons, which are attributed to the special electronic transport mechanism of the fillers in the composites. However, the twin-percolation phenomenon exists when the concentration of MWCNTs is between 5-10 wt.% and 15-20 wt.% in the MWCNTs/SiO₂ composites, while in the graphite/SiO₂ composites, there is only one percolation phenomenon in the graphite concentration of 10-15 wt.%. The unique twin-percolation phenomenon of MWCNTs/SiO₂ is described and attributed to the electronic transfer mechanism, especially the network effect of MWCNTs in the composites. The formation of network plays an essential role in determining the second percolation threshold of MWCNTs/SiO₂.