CdS纳米粒子的制备方法

CdS纳米粒子作为一种十分重要的光电功能材料，近年来引起人们的广泛关注，各种各样的制备方法也由此应运而生。因制备方法不同，所得CdS纳米粒子的粒径、粒度均匀性、纯度及相结构等也各不相同，并进而会对它们的属性（如光电性质）产生很大的影响。如何以材料的形式付诸应用，依据功能的需求，实现对半导体纳米粒子的粒径、形状、粒度均匀性分布以及纯度等的控制是目前CdS纳米粒子制备方法的发展方向。     

功能化CdS纳米晶的合成及CdS/聚苯乙烯纳米杂化材料的研究

以氯化镉和硫化钠为原料,采用巯基乙醇为有机配体,在H2O/DMF的溶剂中,制得分散均匀且表面富含羟基基团CdS纳米晶溶液.我们使用γ-甲基丙烯氧丙基三甲氧基硅烷(MPS)来修饰CdS纳米晶的表面,得到双键官能团化的CdS纳米晶.通过原位自由基聚合方法,成功地得到了聚苯乙烯基CdS纳米晶复合材料.利用傅里叶红外光谱仪(FT-IR)、透射电子显微镜(TEM)、紫外-可见光吸收光谱仪(UV-vis)、X射线衍射分析仪(XRD)、热重分析仪(TGA)、荧光光谱 (PL) 考察了CdS纳米晶及CdS/聚苯乙烯复合材料的结构和光学性能的关系规律.结果表明巯基乙醇表现出良好的光学性能,其配体不是简单的物理吸附于纳米晶表面,而是以化学键的形式和纳米晶表面镉原子相结合.相比于纯的聚苯乙烯材料,聚苯乙烯基CdS纳米晶材料表现出良好的光学和热学性能.     

应用DNA模版自组装CdS纳米线

近年来,由于具有双螺旋补偿结构,DNA分子作为智能模版被广泛应用于设计棒状或管状类的纳米结构.本文报道了应用DNA双螺旋模版将CdS纳米粒子自组装为CdS纳米线.制备的CdS纳米线由几根纳米线紧密缠绕在一起,也呈螺旋形结构,该结构在无机材料中是很少见的.该结构形成的主要原因归功于CdS纳米粒子和DNA分子间的强烈静电互作用,由于含自由基的CdS纳米粒子带负电荷,而氨基的DNA核酸根带正电荷.研究结果表明应用DNA模版制备纳米线是一种简便、高效的技术和方法.同时,DNA模版法也为从底上制备纳米级的材料和物体提供了广阔的空间.     

中空CdS/ZnS纳米核壳材料的制备及其光催化性能探究

采用化学浴法制备聚苯乙烯(PS)/CdS纳米核壳材料,在超声波的作用下采用化学浴法制备PS/CdS/ZnS纳米核壳材料,最后溶液刻蚀除去中心模板,得到中空的CdS/ZnS核壳材料。利用SEM、TEM、EDX、XRD和UV-Vis等测试手段对样品的形貌、成分、粒度、微观结构和吸光度等进行了表征。结果表明:该方法制备的CdS/ZnS纳米材料具有空心双壳层结构,颗粒大小均匀,内壳层厚度为85~100nm,外壳层厚度约为40nm,在可见光下具有良好的稳定催化效能,能够多次回收循环利用。     

CdS纳米棒与二维MoS2异质结的构建及其对罗丹明B的光催化降解的研究

采用钼酸铵作为钼源,硫脲作为硫源,通过水热法构建CdS纳米棒与二维MoS2异质结材料,通过XRD、SEM、TEM、PL、UV-vis等技术对异质结进行表征,结果表明,片状MoS2自组装形成的类球体与CdS纳米棒所形成的异质结(MoS2所占质量分数分别为1％、5％、10％),能够有效提高CdS的可见光吸收强度,光生载流子...     

核壳结构CdS/ZnS@rGA的制备及光催化性能研究

为研究纳米CdS/ZnS@rGA复合材料在可见光下的光催化性能,采用一步溶剂热法合成了以ZnS为壳的CdS/ZnS核壳纳米粒子,将CdS/ZnS核壳纳米粒子附着在rGO纳米片上,并组装成CdS/ZnS@rGA复合气凝胶,用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等对样品进行了表征,通过亚甲基蓝(MB)的光催化降解实验表明：CdS/ZnS@rGA复合气凝胶的形成不仅可以提高CdS的光稳定性,还可以增强对MB吸附能力,同时对MB的降解有明显的促进作用。可见光反应90 min, 50 mg的CdS/ZnS@rGA对100 mL 20 mg/L MB的去除率最高达到99%。经过5次循环实验,该材料仍具有较好的可重复利用性。     

单齿络合剂辅助水热合成CdS纳米棒

以单齿络合剂甲胺为辅助通过水热法制备了CdS纳米棒,所得CdS纳米棒分别用TEM、XRD、Raman和PL等技术进行了表征.研究了络合剂甲胺的浓度对CdS纳米晶体形貌的影响.实验发现当络合剂甲胺的浓度为1、5和20wt％时,水热合成CdS纳米晶体的形貌分别为纳米颗粒、短纳米棒和长纳米棒.这也表明络合剂的类型即单齿或双齿络合剂并不是水热合成CdS纳米棒形成的关键因素.基于实验结果,提出了一个可能的水热合成CdS纳米棒的形成机制:络合物结构—控制机理.     

TiO_2纳米棒-ZnO纳米片分级结构的制备及光电性能

采用两步水热法在无种子层的基础上制备了新颖的TiO_2纳米棒-ZnO纳米片分级结构。采用旋涂辅助连续离子反应方法分别在TiO_2纳米棒阵列和TiO_2纳米棒-ZnO纳米片分级结构中沉积窄禁带半导体光敏剂CdS纳米晶,形成CdS/TiO_2纳米棒复合膜和CdS/TiO_2-ZnO分级纳米结构复合膜。利用SEM、TEM、XRD、紫外-可见吸收光谱、瞬态光电流图谱等分析手段对样品的形貌结构以及电极的光吸收和光电性能进行了表征和测试。结果表明,沉积光敏层CdS后,TiO2纳米棒-ZnO纳米片分级纳米结构膜的瞬态光电流明显高于TiO_2纳米棒阵列膜,尤其是在500nm处光电响应出现明显增强;以P3HT为p型聚合物材料组装杂化太阳电池,光伏性能测试结果表明,以P3HT/CdS/TiO_2-ZnO分级结构复合膜制备的杂化太阳电池能量转换效率可达0.65%,与P3HT/CdS/TiO2复合膜制备的杂化太阳电池的能量转换效率相比提高了58%。     

CdS纳米晶薄膜的制备及光电性能研究

利用化学浴沉积法,以N(CH2CH2OH)3为络合剂,Cd(CH3COO)2·2H2O和(NH2)2CS为前驱体溶液制备了CdS纳米晶薄膜,利用FESEM、XRD考察了前驱体浓度、络合剂浓度、前驱体溶液的pH值、反应温度等因素对CdS纳米晶薄膜的表面形貌、晶粒大小及晶体结构的影响,在最佳工艺条件下可以制得表面平整,结构致密的CdS纳米晶薄膜。UV-Vis光谱表明CdS在短波长区域有较强的吸收,符合作为窗口材料和过渡层的要求;光电性能测试表明CdS具有较好的光电响应,呈特征n型半导体特性。     

掺In纳米ZnO、CdS薄膜结构、光学特性分析

采用真空气相沉积法在玻璃衬底上制备纳米级ZnO和CdS薄膜.研究掺In和热处理对ZnO、CdS薄膜结构、光学特性的影响.实验给出,适当掺杂能够明显改善纳米ZnO、CdS薄膜的物相结构,ZnO薄膜的晶粒尺寸随掺杂含量的增加而减小,CdS薄膜晶粒尺寸随掺杂含量的增加而变大,但薄膜的光透射性有所降低.在短波范围内,ZnO薄膜的光透率好于CdS薄膜;在500 nm～1000 nm范围内,CdS薄膜的光透率好.掺In后ZnO薄膜的光学带宽从3.2eV减小至2.85 eV;掺In后CdS薄膜光学带宽从2.42 eV减小至2.35eV.     

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.     

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.……     

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...     

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.     

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.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

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.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...