负载Pd纳米粒子聚合物颗粒的制备及其催化性能研究

使聚N-乙烯基乙酰胺（PNVA）大分子单体与苯乙烯（St）和丙烯腈（AN）进行三元分散共聚,制得了粒径分布较均一、表面带有花纹状的PNVA-g-PAN/PSt聚合物颗粒,进而以PdCl2为金属源,乙醇为还原剂,采用醇热法将Pd2＋离子还原成Pd纳米粒子并负载于聚合物颗粒表面。透射电子显微镜（TEM）观察表明Pd纳米粒子在聚合物颗粒表面且分布均匀。X射线衍射（XRD）花样图显示Pd纳米粒子为立方晶系,其粒径在9nm左右。热重分析（TGA）结果表明PNVA-g-PAN/PSt聚合物颗粒表面所含Pd纳米粒子的质量分数为0.15%～0.30%。在Pd纳米粒子存在的条件下,可使葡萄糖容易转化为葡萄糖酸,表明该负载型Pd纳米粒子具有良好的催化氧化作用。     

负载型纳米Pt颗粒的制备及催化性能研究

通过分散共聚制备了聚N-异丙基丙烯酰胺接枝聚丙烯腈/聚苯乙烯(PNlPAAm-gPAN/PSt)聚合物微球,以氯铂酸(H2PtCl6)为金属源,乙醇为还原剂,将与酰胺基团配位的铂离子(Pt4 )还原成纳米铂(Pt)颗粒,负载在表面具有特殊形态的聚合物微球表面,制得了分散稳定的负载型纳米Pt颗粒,可用于催化苯胺的聚合等,通过改变反应温度可控制苯胺的聚合速率.     

负载型纳米Pt颗粒的制备及催化性能研究EI北大核心

通过分散共聚制备了聚N-异丙基丙烯酰胺接枝聚丙烯腈/聚苯乙烯(PNIPAAm-g-PAN/PSt)聚合物微球,以氯铂酸(H2PtCl6)为金属源,乙醇为还原剂,将与酰胺基团配位的铂离子(Pt4+)还原成纳米铂(Pt)颗粒,负载在表面具有特殊形态的聚合物微球表面,制得了分散稳定的负载型纳米Pt颗粒,可用于催化苯胺的聚合等,通过改变反应温度可控制苯胺的聚合速率。     

Pd-Ag合金纳米粒子合成及其催化性能研究

采用W/O微乳液法合成Pd-Ag合金纳米粒子并结合微乳浸渍工艺制备了负载型Pd-Ag/Al_2O_3催化剂。利用紫外-可见分光光度计和透射电子显微镜对合成的Pd-Ag合金纳米粒子进行表征,并考察了对乙炔加氢反应的催化性能。结果表明,在聚氧乙烯(4)月桂醚(Brij30)/正辛烷/水微乳液体系中加入聚乙烯基吡咯烷酮(PVP),对生成的纳米粒子起到二次保护作用,Pd与Ag以合金纳米粒子形式稳定存在且粒径大小均一,粒径在1～2nm,可随PVP以薄膜形态负载并分散在Al_2O_3表面。当PVP相对分子质量为8000～10000,cPVP8:c(Pd+Ag)=0.1时,合成的Pd-Ag合金纳米粒子数量最多,粒径最小,制备的Pd-Ag/Al_2O_3催化剂具有良好的乙炔加氢活性和选择性。     

紫外辐照法制备载银P(St-co-MMA)复合微球的研究

以聚乙烯吡咯烷酮(PVP)为分散剂,2,2-二甲氧基-2-苯基苯乙酮(BDK)为引发剂,在乙醇和水(V(乙醇)/V(水)=7/3)的混合介质中,由紫外(UV)光引发苯乙烯(St)和甲基丙烯酸甲酯(MMA)进行分散共聚,研究了影响P(St-co-MMA)收率及其微球粒径的因素;在微球分散液中加入一定浓度的AgNO3,经UV原位催化Ag+还原,制备出了负载有Ag纳米颗粒的P(St-co-MMA)复合微球。用透射电子显微镜(TEM)、激光光散射(LLS)和X射线衍射(XRD)对微球的粒径及Ag纳米颗粒的负载情况进行了表征,发现P(St-co-MMA)微球的粒径均一,可控制在500～800nm之间,Ag纳米颗粒较均匀地负载于微球的表面,平均大小为20nm。     

交联PS微球负载纳米Ni颗粒的制备及表征

采用种子聚合法制备出交联聚苯乙烯(PS)微球,经预处理在微球表面引入官能团,采用化学镀法在微球表面负载纳米级Ni颗粒,利用FI-IR、SEM、XRD等测试手段对其进行表征,结果表明:PS微球粒径均匀,平均粒径约为4.3μm,表面光滑;微球负载的纳米Ni颗粒分散性良好、平均晶粒度为9.41nm.利用负载微球对高氯酸铵(AP)进行催化实验,表明负载微球可使AP高温分解峰降低94.2℃左右.研究表明:采用PS微球负载可提高纳米Ni颗粒的分散性,进而提高了Ni颗粒的催化性能.     

电纺纤维负载钯纳米颗粒的制备及催化α-辛烯加氢性能的研究

通过电纺丝技术制备了聚合物纤维负载钯纳米颗粒催化剂并研究了其催化α-辛烯的加氢性能。聚丙烯腈（PAN）和苯乙烯-丙烯腈共聚物（PSAN）首先负载PdCl2，然后pd^2＋在水合肼的作用下还原成pd^0，并得到PAN-Pd和PSAN-Pd的DMF溶液，最后利用静电纺丝技术制备出了含有钯纳米颗粒的电纺纤维状催化剂，对所制备的催化剂进行了TEM表征，结果显示纤维直径分布范围为70-220nm，纳米钯颗粒直径在15～50nm之间。实验中利用催化剂对α-辛烯催化氢化的结果考察了其活性和重复使用性，还讨论了纤维直径，钯纳米颗粒和载体对催化加氢性能的影响。     

PDEAm接枝PAN/PSt温敏性聚合物微球的制备及表征

利用链转移自由基聚合制得了端羟基化的聚N,N-二乙基丙烯酰胺(PDEAm-OH)低聚物,进而与丙烯酰氯缩合得到温敏性的PDEAm大分子单体,利用FT-IR、1 H NMR和UV对该大分子单体的结构、末端双键含量和温敏性进行了表征,测得该大分子单体的最低临界溶解温度(LCST)为36.4℃。将PDEAm大分子单体与丙烯腈(AN)、苯乙烯(St)在乙醇/水混合介质中进行三元分散共聚,制得了PDEAm接枝聚丙烯腈/聚苯乙烯(PDEAm-g-PAN/PSt)聚合物微球,由扫描电子显微镜SEM观察到的结果表明,聚合物微球表面具有明显的突起形态,其粒径均一,分散稳定性好,改变聚合反应条件可控制所得聚合物微球的形貌和粒径。该聚合物微球的粒径随温度的升高而减小,表明其具有温度敏感性。     

Au纳米粒子混合“肠状”Pd纳米线的Au-Pd/C催化剂的制备与表征

用化学还原法制备Au-Pd双金属混合纳米胶体溶液,然后负载在活性炭上获得Au-Pd/C催化剂,利用TEM表征了纳米粒子负载前后的尺寸与形态,并用XPS技术表征了纳米Au-Pd/C催化剂上Au、Pd的表面化学状态,讨论了胶体溶液混合前后所得到的催化剂上Au、Pd的结合能变化。结果得到了Au混合“肠状”Pd纳米线的Au-Pd/C催化剂,两者结合产生的协同催化效应同时降低了Au和Pd的结合能。     

氮掺杂空心碳纳米球嵌入氮掺杂石墨烯负载钯纳米粒子作为甲酸氧化的高效电催化剂（英文）

低成本、高活性、耐久性好的高效电催化剂对直接甲酸燃料电池的应用起着至关重要的作用。本文采用简单经济的方法,研究了以三维层状多孔结构嵌入氮掺杂石墨烯(NG)的氮掺杂空心碳纳米球(NHCN)负载Pd纳米粒子作为直接甲酸燃料电池催化剂。由于具有独特的氮原子掺杂三维互联层状多孔结构,Pd纳米颗粒尺寸较小的Pd/NHCN@NG催化剂具有较大的催化活性表面积、优越的电催化活性、较高的稳态电流密度和较强的抗CO中毒能力,明显超过传统的Pd/C、Pd/NG和Pd/NHCN催化剂对甲酸电氧化的催化性能。通过优化HCN/GO比,当HCN/GO质量比为1∶1时,Pd/NHCN@NG催化剂对甲酸的催化氧化性能最佳,其活性是Pd/C的4.21倍。本工作开发了一种优越的碳基电催化剂载体材料,为燃料电池的发展带来了广阔的应用前景。     

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.     

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.……     

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.     

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.     

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.