乙烯基倍半硅氧烷杂化膜的制备及其光学性能

利用溶胶-凝胶法制备了乙烯基倍半硅氧烷(VS)和TEOS改性的乙烯基倍半硅氧烷(VST),以VS和VST为中间体,制备了杂化膜材料m-VS和m-VST,用红外光谱、扫描探针电镜对杂化材料进行了表征,并通过紫外-可见-近红外分光光度计研究了VS和VST膜材料的光学性能.结果表明:m-VS在波长200～300nm的紫外吸收最大,在400～700nm涂膜玻璃片的透光率可提高到90%以上,TEOS质量分数为20%时,杂化膜的增透作用最大,可用于日光温室的透光材料.     

POSS/聚合物杂化材料研究进展

多面体低聚倍半硅氧烷(POSS)作为一种特殊的纳米级有机-无机杂化材料,可以与聚合物进行分子级复合,得到具有特殊性能的POSS/聚合物杂化材料,这成为近年来材料科学领域的研究热点之一。从POSS/聚合物杂化材料制备方法出发,主要介绍了几类典型的POSS/聚合物杂化材料的结构和性能,并对POSS/聚合物杂化材料的应用前景进行了展望。     

分子内杂化纳米结构体多面体低聚倍半硅氧烷研究进展

多面体低聚倍半硅氧烷(POSS)是基于化学键合作用形成的分子内杂化体系,其改性后的材料是一类具有广泛潜在应用价值的新型有机-无机杂化材料。文中介绍了多面体低聚倍半硅氧烷单体的结构、性能、单体及其衍生物的合成,以及其改性聚合物材料在航空、航天、卫生、电子等高科技领域内的应用前景。针对国内的研究现状,指出低聚倍半硅氧烷-聚合物杂化体系研究所存在的问题。     

碳纳米管/铁氰化镍/聚苯胺杂化膜对抗坏血酸的电催化氧化

采用循环伏安一步共聚法在碳纳米管修饰的铂基体上制备了立方体的铁氰化镍/聚苯胺/碳纳米管杂化膜;采用循环伏安法和计时电流法测试了杂化膜对抗坏血酸的电催化氧化性能;通过扫描电子显微镜(SEM)观察了杂化膜电极的表观形貌。结果表明,该电极对抗坏血酸具有较高的电催化氧化活性;在0.1 mol/L PBS和0.1 mol/L KNO3的溶液中,该杂化膜电极对抗坏血酸的催化氧化电流与其浓度在1×10-5～1.4×10-4mol/L呈良好的线性关系,相关性系数R=0.996 6,检出限为6.09×10-6mol/L,同时具有较高的灵敏度754.8 mA.M-1.cm-2,并采用计时电流法对抗坏血酸催化氧化的扩散系数和催化速率常数进行了研究。     

导热型硅橡胶电子灌封杂化材料研究

用不同的进料工艺,以六甲基二硅氧烷、四甲基二乙烯基二硅氧烷和硅酸四乙酯为原料,合成一种反应型SiO2单体.由连续进料工艺得到的SiO2单体,羟基含量低,可使硅橡胶的拉伸强度提高10～11倍,击穿强度升高4kV·(mm)-1左右.在硅橡胶-SiO2-Al2O3杂化材料体系中,引入偶联剂3-MPS,有助于α-Al2O3与硅橡胶间界面作用的增强.     

超声波促进SiO_2-环氧杂化树脂的合成及表征

在醇水混合溶剂中利用超声波促进气相白炭黑表面接枝环氧硅氧烷,制备纳米SiO_2-环氧杂化树脂。以激光粒径分析仪、红外光谱、热重分析、旋转黏度计、高氯酸环氧测定法表征合成产物。研究环氧硅氧烷/气相SiO_2质量比及超声时间对产物环氧值及接枝效率的影响。超声波能有效打开白炭黑的次级粒子,经原生粒子表面羟基的缩合反应,接枝环氧基团;杂化树脂的环氧值随环氧硅氧烷/气相SiO_2质量比、超声时间的延长而增加;在8%硅氧烷溶液于70℃超声处理20 min,接枝效率达72%,SiO_2表面羟基接枝率为17%;平均每颗SiO_2粒子表面接枝8×103个环氧基,得环氧值为0.02的杂化树脂。接枝的环氧基团可有效减小气相SiO_2的触变性。     

硫杂芴-三苯胺树枝形分子的合成与电致发光特性研究

选择硫杂芴为π-中心、三苯胺为"枝",合成了新型硫杂芴-三苯胺树枝形分子-2,8-双-[4-三苯胺乙烯基-4',4"-二(三苯胺乙烯基)]硫杂芴(简称STG2),进行了核磁共振谱和质谱表征.以硫芴-三苯胺树枝形分子(简称ST-G2)为发光层,制备了结构为ITO/TCTA/ST-G2/BCP/Mg:Ag的3层发光器件,测试了器件的电致发光性能.该器件在6V开启,12V电压下亮度和效率接近1000cd/m2和0.21m/W.     

PEG大分子硅氧烷制备药物缓释杂化纳米纤维膜

采用Jones试剂对聚乙二醇(PEG)进行修饰并合成端基为-Si(OEt)3的PEG大分子硅氧烷,将其与TiO2溶胶进行共水解缩合,制得PEG/SiO2-TiO2杂化纺丝液。在杂化纺丝液中加入头孢唑啉钠,经静电纺丝法制备载药杂化纳米纤维膜。对杂化电纺纤维膜的结构与形态进行了表征,并研究了其药物释放性能。红外光谱(FT-IR)研究了PEG大分子硅氧烷合成机理和产物结构;扫描电镜(SEM)照片显示,纳米纤维的平均直径约为115 nm,载药纳米纤维平均直径约为130 nm;紫外可见光(UV-Vis)光谱分析表明,载药纤维的初期释放速度较快,随时间推移释放速率逐渐降低,具有良好的药物缓释性能。     

原子转移自由基聚合制备PMMA/POSS杂化材料

以八(γ-氯丙基)倍半硅氧烷(OCP-POSS)为引发剂,通过原子转移自由基聚合(ATRP)制备了PMMA/OCP-POSS有机/无机杂化材料.采用GPC、DSC和TGA对杂化材料的结构与性能进行了表征.结果表明,在DMF、异丙醇、甲苯等3种不同溶剂中均可合成分子量分布较窄的PMMA杂化材料.以DMF为溶剂,所得PMMA/OCP-POSS杂化材料的分子量分布系数可达到1.18.与分子量相当的线形PMMA相比,含OCP-POSS的PMMA杂化材料具有更高的玻璃化转变温度和热稳定性.     

非线性光学含氟PI/SiO2杂化波导纳米材料的研究

以含氟的二胺5,5'-(六氟异丙基)-二-(2-氨基苯酚)及二酐4,4'-(六氟异丙基)-苯二酸酐为单体.首先合成了经酰胺化的主链上带有活性羟基的含氟聚酰亚胺,再通过Mitsunobu反应将活性生色分子分散红1共价链接到聚酰亚胺的侧链骨架上,合成了二阶非线性光学(NLO)含氟聚酰亚胺.采用溶胶-凝胶技术,利用偶联剂APTES制备带有发色团的及含有硅氧烷端分子的聚酰胺酸,其中的Si(OR)3基经水解、缩合后,与正硅酸乙酯在催化剂作用下反应,经杂化、凝胶后,得到热稳定性高的杂化材料.将制得的含氟聚酰亚胺/SiO2杂化材料,利用FT-IR、SEM、TEM、XRD、DSC等手段对其进行了表征.杂化材料的玻璃化转变温度(Tg)为382℃,比纯聚酰亚胺的Tg(306℃)高76℃,表现出优良的高温热稳定性.     

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 ...