Ag_2CO_3/Ag/g-C_3N_4 Z-型异质结的制备及可见光催化降解RhB

通过煅烧处理和沉淀反应合成以Ag纳米粒子为电子媒介的Z-型光催化剂Ag_2CO_3/Ag/g-C_3N_4。在可见光照射下,降解RhB评价Ag_2CO_3/Ag/g-C_3N_4复合物的光催化活性。结果表明:Ag2CO3/Ag/g-C3N4样品显示出比纯Ag_2CO_3和g-C_3N_4更强的光催化活性,当g-C3N4与Ag_2CO_3/Ag质量比为20%时,复合物呈现出最好的光催化性能,这归因于在Ag_2CO_3和g-C_3N_4间形成的Z-型异质结构,其有效促进电子转移速率和光生电子-空穴的分离。Z-型异质结构扩展了可见光吸收波长范围(从450nm到670nm),这是由于Ag纳米粒子表面离子共振的结果。捕获实验证实,在光催化降解RhB反应中,·O_2~-和空穴h~+是主要活性物质,·OH是次要活性物质,并提出了增强光催化活性的机理。     

硫化镉和硫化银与多壁碳纳米管复合材料合成的研究

本文以硝酸镉和硫脲为镉源和硫源,用溶剂热技术在乙二胺和水的混合溶剂中合成CdS/MWNTs复合材料;再以硝酸银和硫化钠为银源和硫源,十二烷基磺酸钠(SDS)为表面活性剂,以水为溶剂在室温下合成Ag2S/MWNTs复合材料并采用TEM、XRD对复合材料进行表征,结果表明:CdS纳米晶和Ag2S纳米粒子成功长到了多壁碳纳米...     

三氟乙酸掺杂的聚苯胺微/纳米管的制备和表征

三氟乙酸(TFA)为掺杂剂,过硫酸铵为氧化剂,在氧化还原反应过程中,通过改变三氟乙酸和苯胺(An)单体的物质的量比([TFA]/[An]),实现了聚苯胺微/纳米结构的可控自组装。在较低的苯胺浓度下,即[TFA]/[An]=2或1时,聚苯胺形态为颗粒状;随着反应体系中苯胺浓度的升高,物质的量比[TFA]/[An]=0.5,0.25时,产物能形成聚苯胺微/纳米管,其外径大约为200 nm~300 nm,空心处内径大约为30 nm~80 nm,微/纳米管表面凹凸不平,存在圆球状聚苯胺颗粒。聚苯胺微/纳米管为掺杂态,在电子吸收光谱中,分别在350 nm附近和630 nm处出现吸收峰。聚苯胺微/纳米管的电导率为10-3S/cm~10-4S/cm。XRD结构分析表明,聚苯胺微/纳米管为部分结晶性材料。     

L-半胱氨酸法制备银纳米线材料及其电化学性能

为了加快银纳米线材料的合成速度,在制备过程中利用L-半胱氨酸作为反应过程中形成Ag2S胶体的硫源,将合成银纳米线的前驱体硝酸银的浓度提高到了1 mol/L,利用扫描电子显微镜、透射电子显微镜和X射线衍射仪对制备的银纳米线材料进行了表征,利用循环伏安法和电化学阻抗法对银纳米线修饰的铂电极电化学性能进行了研究.结果表明:L-半胱氨酸的引入可以明显降低体系中硝酸的浓度,提高银纳米线的产量,使得银纳米线的合成时间降低到20 min;电化学实验结果表明:制备的银纳米线材料具备良好的电子传递能力、较大的比表面积和较强的电化学性能,利用这些特点有望改善无酶传感器的性能.     

双修饰Fe3O4/CdSe/CdS荧光磁性复合物的制备及其表征

采用共沉淀法制得Fe3O4溶胶,用γ-缩水甘油醚氧丙基三甲氧基硅烷(KH-560)对其表面进行改性,制得有机硅改性的纳米Fe3O4磁性粒子;用L-半胱氨酸盐酸盐(L-Cys)将油相的CdSe/CdS转成水相并带上氨基的CdSe/CdS纳米晶;将其复合制备了Fe3O4/CdSe/CdS荧光磁性双功能纳米复合物颗粒。该Fe3O4/CdSe/CdS复合物颗粒平均尺寸约为40nm,饱和磁化强度为21.287A.m2/kg,该纳米粒子既具有优异的荧光特性,也具有较强的超顺磁性。     

反相微乳液合成单分散的四方形SnO_2纳米晶(英文)

通过设计反相微乳液反应体系,在水热条件下缓慢氧化SnF_2,合成了单分散的四方形SnO_2纳米晶,利用X射线多晶粉末衍射、扫描电镜、高分辩透射电镜对合成样品的形貌和结构进行了表征.实验结果表明,通过控制油胺的添加量调控微乳液水相的pH值,可以对SnO_2的形貌进行调控.使用适当量的油胺,可以获得分散性极好、大小为10 nm左右的规则四方SnO_2纳米晶.合适的pH值有利于晶核的定向生长,从而在微乳液反应器中形成了规则的SnO_2四方纳米晶。     

Ag-TiO_2纳米悬浮液的制备及其导热性与黏性

为了提高TiO_2纳米流体的导热性能,将Ag纳米颗粒与TiO_2纳米颗粒混合,利用两步法制备出不同银钛物质的量比的Ag-TiO_2纳米悬浮液,并研究其导热性能与黏性。采用X射线衍射仪和扫描电子显微镜表征Ag-TiO_2纳米颗粒晶型和形貌;通过沉降法、激光粒度分析和吸光度测量法探究Ag-TiO_2纳米悬浮液的稳定性。结果表明:Ag纳米颗粒含量低有利于Ag-TiO_2纳米悬浮液稳定;质量分数为0. 3%的银钛物质的量的比为1∶6、1∶4、1∶2的Ag-TiO_2悬浮液,导热系数在常温下比TiO_2悬浮液导热系数分别增加了0. 83%、1. 66%、2. 33%,而黏度与基液水相比分别增加了37. 5%、27. 5%、22. 5%;银钛物质的量比为1∶2的Ag-TiO_2纳米悬浮液导热系数高于银钛物质的量比为1∶6和1∶4悬浮液的,而其黏度却低于银钛物质的量比为1∶6和1∶4悬浮液的。     

无模板法可控合成多层次结构二氧化钛微球

以1,4-二氧六环为溶剂,采用溶剂热法成功实现无模板法可控合成二氧化钛多层次结构微球。通过系统改变反应体系中浓盐酸与四异丙醇钛(TTIP)相对物质的量比能够有效调控二氧化钛形貌。当浓盐酸与TTIP物质的量比控制在0(或0.7或0.9)、1.8、3.6与5.7时,所得产物分别为纳米颗粒构建二氧化钛微球、纳米棒修饰二氧化钛微球、纳米棒花菜结构以及纳米棒海胆结构。在成功进行形貌调控的基础上,进一步探讨了二氧化钛多种结构的形成机理,并对其光催化产氢性能进行了表征。研究发现,在这4种结构中,纳米棒修饰二氧化钛微球具有最佳的光催化性能,这可能是由于同时存在金红石和锐钛矿两种晶型而形成异质结结构所导致。     

微乳液法制备纳米TiO_2粉体的研究

以硫酸法钛白粉生产中间产物偏钛酸为原料,通过微乳法制备纳米TiO_2粉体,分析微乳法制备纳米粒子的反应过程及机理,研究反应物浓度、水与表面活性剂摩尔比以及表面活性剂用量对纳米颗粒粒径的影响。研究结果显示通过此微乳液体系,在偏钛酸溶液中钛盐摩尔浓度为2.0mol/L、水与表面活性剂摩尔比为50∶1、正己醇与曲拉通X-100的质量比为1∶0.3条件下,制备的TiO_2纳米粉体形状规则,平均粒径为25nm,具有分散度好、粒度分布均匀等特点。     

硫酸钙纳米棒的简易合成与光致发光特性

用水(溶液)/AEO/环己烷/正戊醇的微乳体系, 制备了分散性良好、尺寸均一的单斜结构CaSO_4·0.662H₂O 纳米棒, 其平均直径为50nm, 长度为800~1600nm. 研究表明, 当水/ 表比(ω)为6~15、油/表比(γ)在5~12之间、反应物浓度为0.05~0.3mol/L时, 适合于棒状硫酸钙的合. 性质研究发现, 纳米硫酸钙在339nm处有较强的紫光发射, 这在纳电子器件等领域有广阔的应用前景.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.