聚苯乙烯微球表面合成CdSe纳米晶

以聚苯乙烯(PS)单分散微球为模板, 利用表面化学沉积, 在PS微球表面合成了CdSe纳米晶. 透射电子显微镜(TEM)观察发现, CdSe纳米晶以岛状形貌分布在PS微球表面, X射线衍射(XRD)分 析显示合成CdSe纳米晶具有立方相结构. 通过对产物形貌的演变过程进行观察分析表明, PS球周围的双电层结构对该形貌的形成起决定作用.     

棒状纳米微晶纤维素诱导制备花状TiO2纳米晶体

以棒状纳米微晶纤维素(Nanocrystalline cellulose,NCC)为形貌诱导剂,TiCl4为原料,采用水解法在70℃的温度下反应4～6 h,制备了TiO2花状纳米晶体.采用TEM、HRTEM、XRD和FTIR对不同条件下制得的TiO2晶体的微观形貌、晶粒尺寸和晶相组成进行了表征,探讨了TiCl4的用量及反应时间对晶体形貌和晶型的影响,并对其形成机理进行分析.纳米微晶纤维素表面富含大量羟基,可与TiO2之间形成氢键连接,促使TiO2在其表面的异质成核和生长,同时纳米微晶纤维素在TiO2表面的吸附作用,改变了各晶面的表面能和生长速度,使TiO2沿着[110]方向优先生长形成一维针状物,针状物再进一步聚集形成花状聚集体.以甲基橙为目标污染物,测试了所得TiO2纳米花状晶体的光催化性能.结果表明,随着TiCl4用量的增多及反应时间的延长,所制得的TiO2纳米晶体中金红石含量增多,形貌逐渐复杂化,光催化性能下降.     

水热法仿生合成纳米二氧化锰及其形貌调控

以高锰酸钾为锰源,甘氨酸为模板在硝酸体系中仿生合成纳米二氧化锰。利用SEM、XRD、N2吸附脱附对制得样品进行表征,通过改变反应温度和时间对样品的晶型晶貌进行定向调控。结果表明,在反应时间1h,温度为70℃得到了片状花球-MnO2、90℃得到棒状-MnO2;而在70℃下反应8h则制得针花状-MnO2,通过实验分析得出纳米二氧化锰微观晶貌和晶型的演变规律。     

水热合成棒状氧化钇粉体的生长过程和生长机理的研究

以氨水作为矿化剂,硝酸钇为原料,利用低温水热法合成棒状纳米晶和微米晶。进一步利用XRD、SEM、TEM对水热合成产物进行了表征。研究结果表明,在pH值=9、水热合成温度80℃、反应时间为4h时得到低结晶度的片状水合氧化钇纳米晶。随水热反应的进行,无定形水合硝酸氧钇在高温高压条件下开始结晶形成Y2(OH)5(NO3).H2O,随着水热反应温度和压力的进一步升高,组成由Y2(OH)5(NO3).H2O逐渐向Y4O(OH)9(NO3)转变。当合成温度升高到180℃,合成了结晶度完好的水合硝酸氧钇棒型微米晶。经过600℃的热处理成功得到了棒状结构的氧化钇。水热条件下不同形貌水合硝酸氧钇的生长过程遵循溶解-再结晶机制,并且存在重结晶生长。     

CdSe纳米晶／MEH—PPV复合型光电池研究

采用单前驱体热解法、高温微乳液法合成了高质量的CdSe纳米晶,将CdSe纳米晶按照一定比例与聚苯乙烯撑（MEH—PPV）共混制成光电池,利用TEM、XRD等研究了纳米晶的形貌结构特征,结果显示,所合成的半导体CdSe纳米晶为闪锌矿结构,直径在3-5nm之间,复合光电池最好的器件能量转化达到0．85％,     

CdSe薄膜的溶剂热制备及其光电化学性能研究

以CdCl2.2.5H2O为镉源,以Se粉为硒源,在苄胺体系中,180℃溶荆热条件下制备了CdSe纳米晶薄膜.并用XRD、SEM、TEM、UV-vis等对产物进行了一系列的表征,结果表明在该条件下可以得到粒径在10～20nm、较为均匀的CdSe纳米晶薄膜.同时在标准的三电极体系下,测试了CdSe纳米晶薄膜电极的光电化学...     

立方体形貌的BaTiO3纳米粒子的融盐法制备与表征

用TiO2和Ba(OH)2为钛源和钡源,以NaOH和KOH为熔剂,采用融盐法成功地合成了Ba-TiO3纳米粒子.用XRD、SEM、TEM、ED、EDS和FT-IR对产品的结构、形貌和成份进行了表征.结果表明,在反应温度为200℃、反应时间为24h时能得到形状为立方体、大小分布均匀、粒径约为20～55nm的钛酸钡纳米粒子;随反应时间增加,粒子形貌由立方体逐渐变为球形,且粒径增大.所得产品为立方晶相、结晶良好、纯度高的BaTiO3纳米粒子.另外,还初步探讨了融盐法制备BaTiO3纳米粒子的形成机理.     

反应时间对CaWO_4∶Eu~(3+)纳米晶形貌及发光性能影响

采用溶剂热法,以钨酸钠(Na_2WO_4·2H_2O)和氯化钙(CaCl_2)为原料,在V(醇)∶V(水)=3∶1,十二烷基磺酸钠(SDS)摩尔分数为1%,pH=7,180℃下,制备出了四方晶系结构的球形铕掺杂钨酸钙(CaWO_4∶Eu~(3+))纳米晶。通过X射线衍射(XRD)、扫描电镜(SEM)及荧光光谱(PL)对不同条件下制备出的产物的物相、形貌以及荧光性质进行表征,探讨了反应时间对产物形貌及发光性能的影响。结果表明,在不同反应时间下合成出了不同形貌的CaWO_4∶Eu~(3+)纳米晶。从荧光发射光谱可以看出,反应时间为24h的体系下合成出的球形CaWO_4∶Eu~(3+)纳米晶在393nm激发下于612nm处有强发射峰。由此,反应时间对CaWO_4∶Eu~(3+)纳米晶的物相和形貌及发光性能起到重要作用。     

羧甲基纤维素钠模板法制备纳米硒

报道了羧甲基纤维素钠存在下制备纳米硒的方法,得到了球形、棒状和线状纳米硒。研究了反应时间、反应物浓度、温度、超声等实验条件对产物粒度大小、形貌的影响,采用光谱法、透射电镜、扫描电镜、X射线衍射等手段对产物进行了表征。     

单分散硫化铜纳米晶的生长及调控

以氯化铜、油胺和硫粉为反应物,利用热注入化学反应制备单分散硫化铜纳米晶.通过加入其它表面活性剂可以对纳米晶的尺寸,形貌和稳定性进行调控.这些表面活性剂包括苄胺、油酸、硬脂酸、十二烷基硫醇、三辛基氧化膦和烷基胺等.在一定条件下硫化铜纳米晶还可以自组装为蛇状纳米结构和玉米棒状纳米结构.最后利用X射线衍射仪、透射电镜和高分辨透射电镜对硫化铜纳米晶的结构和形貌进行了表征.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

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.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

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.……     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

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.     

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.     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.     

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.