甲醇介质中溶剂热合成六方CdS中空纳米球

以甲醇为溶剂, 硝酸镉和硫脲为原料, 通过溶剂热法合成了CdS中空纳米球, 采用TEM、EDS和XRD对样品形貌和结构进行了表征. TEM与EDS分析显示产物主要为洋葱状CdS中空纳米球, 外径为5～17nm, 空腔直径为3～14nm. XRD分析结果表明,CdS中空纳米球为六方纤锌矿结构. 并初步考察了醇类溶剂对形成CdS纳米结构的影响. 结果表明,当以无水乙醇或正戊醇为溶剂时,产物分别为CdS颗粒团簇或CdS纳米颗粒组装的微球,说明甲醇对中空结构的形成起了重要作用. 以甲醇作溶剂时, 中空纳米球的形成可能是CdS纳米片层高压下卷曲形成的.      

分步水热热解合成单分散碳微球

以水溶性淀粉为原料,经分步水热处理和高温热解制备出粒径范围为0.1~0.4μm的碳微球,分别采用扫描电子显微镜(SEM)、X射线衍射(XRD)仪和傅里叶变换红外光谱仪(FT-IR)对碳微球的形貌、晶体结构和化学键进行分析,并探讨了反应条件对碳微球形貌和结构的影响。结果表明,第一步水热反应中保温温度和时间对碳微球的分散性有重要的影响,在保温温度为160℃,时间为2h的工艺条件下获得的碳微球表现出最优的分散性;第一步水热后取出的部分溶液与第二步水热中新加溶液的体积比、第二步水热中新加溶液的浓度是影响碳微球平均粒径和产量的重要因素,即平均粒径和产量随着溶液体积比的减小而增大,而随新加溶液浓度的增大而增大;但上述工艺参数对碳微球的晶体结构和化学键影响甚小。     

中空CdS核壳材料在可见光下催化处理印染废水的探究

采用水浴法以醋酸镉、硫代乙酰胺为前驱体,聚苯乙烯微球为模版合成PS@CdS核壳复合材料,高温煅烧后得到中空的CdS核壳材料。利用SEM、TEM、XRD和FT-IR等测试手段对样品的形貌、成分、微观结构和粒度等进行了表征。结果表明:水浴法制备的CdS纳米材料具有空心结构,颗粒均匀呈杨梅状,壳层厚度约90~95nm,在可见光下具有良好的催化效能。     

硫化镉-聚苯乙烯微球的简易合成及在紫外固化涂料中的应用

文中用烯丙基硫脲(AT)为功能辅助单体与苯乙烯聚合,并为Cd2+提供配位点,在Cd2+存在下,无皂乳液聚合制备了聚合物微球。由硫代乙酰胺(TAA)释放S2-,形成CdS,成功制备CdS/PS纳米复合微球。研究表明,控制乙酸镉(CdAc2)、偶氮二异丁基脒盐酸盐(AIBA)、TAA加料量可制得如球形、锥形、圆形的不同形貌复合粒子。再用环氧丙烯酸树脂为成膜物,将所制复合微球添到涂料基料中,制备了紫外光固化有机/无机纳米杂化荧光涂膜,其具有良好荧光性,最佳实验配方下光固化时间为10 s,固化涂膜铅笔硬度为5 H,耐冲击强度达到50 kg·cm,可耐受碱、酸及水的浸泡72 h以上。     

CdS空心微球的制备与表征

以不同粒径的苯乙烯-丙稀酸(酯)共聚物(PSA)乳胶粒为模板,制备出均匀的PSA/CdS核壳复合结构的微球,用有机溶剂溶去模板PSA后,分别制备了不同粒径的CdS空心微球.透射电镜分析结果表明,以直径250、340和600nm的PSA乳胶粒为模板,所得CdS空心球的粒径均匀,直径分别为340、450和800nm.紫外可见吸收光谱显示3个CdS空心球样品的最大吸收分别为480nm、410nm和485nm.     

聚丙烯酸微凝胶的细乳液聚合法制备与表征

以丙烯腈(AN)、二乙烯苯(DVB)等为原料,通过细乳液聚合法合成出交联聚丙烯腈(PAN)纳米微球,在碱性条件下水解制得聚丙烯酸(PAA)微凝胶。通过红外光谱(FT-IR)、透射电镜(TEM)和激光粒度仪对PAN微球和PAA微凝胶的结构、形貌和性质进行了表征,研究不同pH缓冲液下PAA微凝胶的响应行为。结果表明,PAN微球形貌为不规则球形、平均粒径105nm,PAA微凝胶形貌为规则球形、平均粒径230nm,PAA微凝胶在不同pH缓冲液中表现出良好的pH响应性。     

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.     

聚甲基丙烯酰胺基偶氮苯微球的制备及其光响应性

利用对氨基偶氮苯与甲基丙烯酰氯反应合成了甲基丙烯酰胺基偶氮苯(MAAAB),以MAAAB为单体,偶氮二异丁腈(AIBN)为引发剂,聚乙烯基吡咯烷酮(PVP)为分散剂,乙醇/水为分散介质,利用分散聚合法制备了聚甲基丙烯酰氨基偶氮苯(PMAAAB)微球,同时考察了引发剂、分散剂浓度以及醇水比对微球形貌和粒径的影响。采用红外光谱、凝胶渗透色谱、扫描电镜、纳米粒度仪等对单体和聚合物的结构、微球形貌和粒径进行了表征和测试,并考察了PMAAAB微球的光响应性。结果表明,PMAAAB微球的粒径在0~2.0μm,粒径分布较窄;PMAAAB微球的粒径随分散剂用量、醇水比的增加而减小;引发剂用量增加,微球粒径增大;随着UV照射时间的延长,微球粒径变大,照射80 min后达到平衡;可见光作用下,微球粒径及其分布均减小,照射20 min后达到平衡;在紫外-可见光交替作用下,PMAAAB微球粒径表现出可逆的变化。     

埃洛石纳米管热敏复合微球的制备及吸附性能

通过种子乳液聚合法在埃洛石纳米管(HNTs)表面包覆聚N-异丙基丙烯酰胺(PNIPAM),制备了HNTs/PNIPAM热敏复合微球。利用红外光谱仪(FT-IR)、粒度仪、比表面积测试仪(BET)对复合微球的结构和形貌进行了分析,通过分光光度法研究了复合微球对亚甲基蓝的吸附性能。结果表明,复合微球粒径约为1.8μm,比表面积约为18.2m2/g;其体积相转变温度约为33.6℃,具有热敏性。实验条件下,复合微球对溶液中亚甲基蓝(MB)的吸附率为99.4%,吸附MB后的复合微球在室温下再生60min后,MB解吸附趋于平衡,进一步在40℃进行解吸附时,微球中MB可以进一步释放。     

不同形貌的TiO_2微球可控合成与机理研究

在盐酸溶液体系中,以TiCl4为原料,采用水热法制备分形结构金红石TiO_2微球。通过对水热温度、反应物配比、加入NaCl等水热条件的考察,讨论了不同水热条件对TiO_2晶型和形貌的影响。利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对不同形貌的TiO_2微球样品进行表征。SEM分析表明水热合成TiO_2微球的形貌和大小可控,XRD表明合成的TiO_2微球均为金红石型,最后提出了金红石型TiO_2微球的合成机理。     

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.……     

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.     

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...     

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 ...