层层自组装SiO_2/木材复合材料的超疏水性及其形成机制

通过层层自组装技术制备纳米SiO_2薄膜,利用1H,1H,2H,2H-全氟辛基三乙氧基硅烷(POTS)作为疏水改性剂制备出了超疏水木材。EDXA、FT-IR、XRD、SEM分析证实经过层层自组装处理后,木材表面生长出了纳米SiO2薄膜,后续修饰处理的POTS试剂后与纳米SiO_2通过化学键结合生长于木材表面。接触角测试显示,当木材表面自组装5层后,制备的木材具有超疏水性能,接触角高达161°。TG分析表明超疏水木材具有较好的热稳定性。超疏水木材表面的形成机制可以归纳为层层自组装的纳米SiO_2薄膜在木材表面构建了微纳米级粗糙结构,并经后续低表面能物质POTS的修饰处理使得木材表面由亲水转变为超疏水。     

静电纺丝法制备超疏水氟硅改性纳米SiO_2/PET共混膜

利用1H,1H,2H,2H-全氟辛基三氯硅烷对SiO_2纳米粒子进行表面改性,制备得到氟硅改性SiO_2纳米粒子(M-SiO_2),并将其与聚对苯二甲酸乙二酯(PET)共混后溶于六氟异丙醇(HFIP)溶剂中进行静电纺丝。采用接触角测量仪、扫描电镜和X射线光电子能谱研究了M-SiO_2/PET电纺膜的疏水性能、表面形貌以及化学组成。结果表明,静电纺丝法制备的M-SiO_2/PET共混电纺膜对水的接触角可高达155.2°,并且对水的滞后角仅为3.4°,即具有超疏水性能。     

仿生超疏水棉织物的制备与表面分析

以荷叶表面微/纳米结构为参考模型,先用硅溶胶处理天然棉织物,再用N-β-氨乙基-γ-氨丙基聚二甲基硅氧烷(ASO-1)对其进行修饰,获得了微/纳米二元粗糙的超疏水织物,水滴在该织物表面接触角可达160.5°。场发射扫描电子显微镜(FE-SEM)观察发现超疏水纤维表面存在大量均匀分布的纳米微凸体。接触角分析表明织物织造过程中形成的微米级粗糙度和ASO-1膜的存在是织物疏水的主要原因,纳米微凸体能减少纤维与水的接触面积,提高水在纤维表面的接触角,使织物由疏水转变为超疏水。最后用X射线光电子能谱仪(XPS)证实了纤维表面SiO2粒子和ASO-1膜的存在。     

钢铁表面超疏水膜的制备与表征

采用水热法结合氟硅烷修饰直接在钢铁表面制备超疏水膜。疏水膜的疏水性与钢铁基底的微纳米结构有重要关系。结果表明,以乙二胺为溶剂,经140℃水热反应4h和160℃水热反应5h,可以在钢铁表面制得具有次级网状结构的正八面体、花状等微纳米精细结构,再经氟硅烷修饰后表现出良好的超疏水性,与水滴的接触角分别达到156.49和165.31°。XRD的分析结果表明,该微纳米结构的主要成分是Fe3O4,它的形成一方面提供了制备超疏水表面所必须的微纳米精细结构,另一方面又为与氟硅烷发生反应生成牢固的薄膜创造了条件。电化学分析结果表明,超疏水膜层的存在显著降低了钢铁基底的腐蚀倾向。     

SiO_2/PDMS复合透明超疏水涂层的制备与性能研究

使用十八烷基三氯硅烷对纳米SiO_2原料进行了表面疏水改性,然后采用二步旋涂法在玻璃基片上制备了SiO_2/聚二甲基硅氧烷(SiO_2/PDMS)复合透明超疏水涂层。结果表明:纳米SiO_2及其团聚体镶嵌在硅橡胶基体表面形成粗糙结构,SiO_2/PDMS复合材料表面水接触角高达164.5°,水滚动角为4.7°;另外,SiO_2/PDMS复合材料在350~800nm波长范围其透光率大于75%,具有较高的透明性。     

化学浴沉积法制备防污自洁聚偏氟乙烯膜

基于"荷叶效应"原理,利用聚偏氟乙烯(PVDF)涂膜构筑微米结构,氧等离子体诱导化学沉积法构筑纳米结构。采用接触角测量仪、原子力显微镜及X光电子能谱仪等研究了PVDF膜表面的微结构及化学组成与疏水性能的关系。结果显示,PVDF溶液涂膜后可形成直径8μm的微球,甲基三氯硅烷修饰的PVDF膜与水的接触角为157°;二甲基二氯硅烷/甲基三氯硅烷混合液修饰的PVDF膜的表面接触角为155°,滚动角2°;集灰实验证明,两种修饰方法制备的PVDF膜均具有良好的防污自洁性能。     

A3碳钢表面PDMS-SiO_2/PANI超疏水膜的制备及其防腐蚀性能

为了提高超疏水膜的使用寿命,通过改变聚二甲基硅氧烷修饰的二氧化硅(PDMS-SiO_2)纳米粒子的含量,用简单的提拉法在A3碳钢表面构建一层包含聚苯胺(PANI)、PDMS-SiO_2和环氧树脂的超疏水膜。通过扫描电镜(SEM)、红外光谱仪和接触角测量仪对其表面进行表征。PDMS-SiO_2纳米粒子不仅能够增加膜的表面粗糙度,而且能够降低膜的表面能,当PDMS-SiO_2含量达到25.0%时,所制备的膜具有超疏水性。采用电化学工作站对复合膜的防腐蚀性能进行研究,结果表明:与传统的聚苯胺环氧树脂涂层相比,采用PDMS-SiO_2/PANI构建的超疏水膜具有更好的防腐蚀效果。     

氟化PVA-SiO2薄膜单面疏水性的研究与表征

目的 研究开发一种具有单面疏水性能的聚乙烯醇薄膜材料作为包装材料。方法 将质量分数为12%、醇解度为88%的PVA溶液与质量分数为5%的纳米SiO2溶液按体积比为1∶1混合并加热搅拌,通过流延干燥的方式制备PVA-SiO2薄膜。然后分别用体积分数为2.5%,5%,7.5%的十七氟癸基三甲氧基硅烷（FAS）-乙醇溶液以浸泡方式修饰薄膜的其中一面,并通过溶解性测试、接触角测试、场发射扫描电子显微镜（FE-SEM）、傅里叶变换衰减全反射红外光谱测试（ATR-FTIR）等方法表征改性结果。结果 结果表明薄膜单面疏水性得到改善,改性后的薄膜在水中的溶解时间增加,且接触角均在120°以上,表明FAS起到了降低表面能的作用;FE-SEM结果显示,Si元素含量对薄膜的疏水性能有着重要影响;ATR-FTIR显示,FAS改性成功将氟原子引入到薄膜表面,且增加了硅原子的数量。其中用质量分数为5%的FAS-乙醇溶液修饰后的薄膜疏水性最好,接触角达到了126.21°。结论 与未改性薄膜相比,经FAS单面疏水改性的PVA-SiO2薄膜疏水性能得到大大提高,拓宽了PVA薄膜材料的应用领域。     

双层透明耐磨超疏水膜层的制备及界面结构控制

以正硅酸乙酯为前驱体,以溶胶-凝胶法制备的SiO_2溶胶作为黏结剂,首先将SiO_2溶胶在玻璃上旋涂成膜作为底层黏结层,再将亲水型气相SiO_2纳米颗粒与SiO_2溶胶混合后在底层上旋涂成膜作为上层微纳米凹凸膜层,制得双层透明耐磨微纳米凹凸膜层;同时采用KH560嫁接改性的SiO_2纳米颗粒替代未处理的SiO_2纳米颗粒,制得改性双层透明耐磨微纳米凹凸膜层,研究了膜层制备工艺以及SiO_2纳米颗粒改性对膜层界面结构的影响。结果表明,当旋涂转速为400 r/min、膜厚为1.39μm时,底层黏结层具有优异的透光性和耐磨性;紫外臭氧照射20 min后,水接触角为0°,形成高化学活性的亲水性表面。经氟硅烷表面修饰,双层透明耐磨微纳米凹凸膜层和改性双层透明耐磨微纳米凹凸膜层的水接触角分别为151.23°、150.82°,呈现超疏水性;在1 kg/cm~2的荷载作用下,往复打磨200次后,它们的水接触角分别达到121.97°和126.45°,平均面粗糙度保持率高达51.62%和66.33%,下降幅度小,呈现优良的耐磨特性。耐磨特性与界面处的空隙、孔洞密切关联;SiO_2纳米颗粒的改性能够有效地减少界面处的空隙、孔洞,提升膜层的耐磨特性。     

铜表面的纳米结构制备及其浸润性研究

通过水热法在铜表面成功制备了一层具有纳米机构的超亲水薄膜,其表面的接触角可达到6°。随后用氟硅烷对其表面进行修饰,使表面由超亲水变成了超疏水,接触角达到了156°,滚动角小于10°。用扫描电镜、接触角测量仪、X射线衍射仪等技术对超疏水表面进行了表征和分析。X射线衍射分析表明,铜表面的片状结构为氧化铜。扫描电镜对铜表面形貌观察显示,温度、反应时间对表面的形貌影响比较大。片状结构之间的空隙和低表面的修饰是导致超疏水性能的主要原因。将铜超疏水表面放在不同高度的水底一段时间,取出后对其接触角进行测量,结果发现超疏水性能消失,接触角变小。     

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.     

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.     

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.……     

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.     

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.