丝素蛋白膜表面的等离子体磺酸化及体外抗凝血性能

从蚕丝中提取的丝素蛋白（Silk fibroin）制备成薄膜,首次采用二氧化硫等离子体处理在材料表现引入了磺酸基因;同时丝素蛋白膜用氨气等离子体处理后在表面接入氨基,利用1,3－丙磺酸内酯与氨基的反应在材料表面接枝磺酸。采用X光电子能谱和全反射红光谱分析材料的表面性质。材料的体外抗弟血性能由外凝血时间;凝血酶原时间（PT）、部分凝血活酶时间（APTT）和凝血酶时间（TT）作为评价标准。结果表明两种处理方法均能在丝素蛋白膜表面有效地接枝磺酸基因,而且材料的抗凝血性能有显著提高。     

聚乙二醇缩水甘油醚对丝素蛋白膜的改性

合成了不同分子量的聚乙二醇缩水甘油醚（PEGO），用1H－NMR，红外吸收光谱对其进行了表征，并将其用于改性丝素膜，用X射线衍射法，氨基酸分析仪研究了PEGO改性丝素膜的结构，并对改性丝素膜中的溶出率以及力学性能进行了测试，结果表明，PEGO可以改变丝素膜的结构，降低丝素大分子的溶出率，改性后的丝素膜具有较好的拉伸强度和较大的断裂伸长率，得到了较为柔韧的改性丝素膜。     

丝素改性胶原膜的低温等离子体改性及体外抗凝血性研究

选用SO2、NH3、CO2三种工作气体，采用低温等离子体技术对丝素改性胶原膜进行了表面改性。运用X光电子能谱分析了材料的表面性质。材料的体外抗凝血性能由体外凝血时间——凝血酶原时间(PT)、部分凝血活酶时间(APTT)、凝血酶时间(TT)作为评价标准。结果表明，SO2、CO2等离子体处理可分别在材料表面引入磺酸和酸酸基团，材料的体外抗凝血性得到很大的改善。NH3等离子体处理可以增加材料表面的氨基的数目，它对材料的抗凝血性没有贡献。     

CVDP制备的聚对亚苯基二亚甲基的表面磺化改性

采用化学气相沉积聚合(CVDP)的方法制备了聚对亚苯基二亚甲基(PPX)涂层,再通过发烟硫酸的化学表面改性成功地在PPX的芳香环上引入磺酸基团,可作为进一步功能化的反应基团.与PPX相比,表面磺化改性PPX(PPX-SO3Na)的接触角变小,亲水性增加,更有利于作为生物医用材料.采用原子力显微镜(AFM)测定PPX和磺化PPX的表面形貌,结果表明,表面磺化改性后的PPX变得更光滑,更有利于作抗凝血涂层材料.Fenton试剂测得PPX-SO3Na的抗化学氧化时间略低于PPX,但由于膜的主链主要是由苯环连接而成的,相对其它常用聚合物来说依然具有较好的抗化学氧化性能.     

浸渍法在聚丙烯基体上负载二氧化钛薄膜

采用TiO2浆料浸渍法在聚丙烯塑料上负载纳米二氧化钛薄膜.研究了不同表面处理方法、表面处理条件和浆料固相含量对TiO2薄膜的形成和结构的影响.用扫描电镜观察了TiO2薄膜的表面形态,用傅立叶变换红外光谱仪和X射线光电子能谱分析了表面处理后聚丙烯表面所带基团、原子及化学态.研究表明,经过离子溅射表面镀Ti膜处理和表面磺化处理后,可改善聚丙烯表面与TiO2粒子间的亲和度,以镀Ti膜的表面形成的TiO2薄膜结构较均匀致密.表面磺化处理存在最佳时间,时间过长,会使表面产生点蚀,影响成膜质量.最佳处理时间与磺化速率有关.浆料中TiO2含量越高,浆料粘度越大,膜越容易开裂和脱落,较低粘度的浆料可获得结构较均匀的膜.     

聚偏氟乙烯微孔膜一步法亲水化改性研究

采用高能电子束预辐照接枝的方法,研究了液相丙烯酸(AAc)和苯乙烯磺酸钠(SSS)双元混合体系对聚偏氟乙烯(PVDF)微孔膜的接枝改性,用一步法直接制备了含有羧酸基团和磺酸基团的强亲水性PVDF微孔膜.考察了辐照剂量、反应时间、反应温度、单体浓度、单体配比以及反应溶液pH值等对接枝率的影响.采用FT-IR、接触角和水通量表征改性前后的膜表面性质和膜性能.结果表明,接枝改性后膜的亲水性增强,接触角随接枝率的增加而降低,水通量随接枝率的增加呈现出先升后降的变化,这主要是由于高接枝率时膜表面和膜孔被接枝链堵塞.     

丝素抗凝血材料的研究进展

综述了丝素材料在抗凝血方面的研究进展,主要从材料表面肝素化、硫酸化、低温等离子体接枝改性、材料表面内皮化或者几种方法协同作用等展开,对比评述了其优缺点,阐述了对丝素材料表面进行抗凝血改性的研究进展.     

磺化聚芳醚酮砜的热降解动力学

通过热重分析仪(TGA)对作为质子交换膜材料使用的磺化聚芳醚酮砜(SPAEKS)进行了热性能研究.采用不同的升温速率,分别用Kissinger方法和Flynn-Wall-Ozawa方法研究了不同磺化度的SPAEKS在氮气氛围下磺酸基团完全脱落前的热降解动力学.研究表明,通过Kissinger方法计算得到SPAEKS的活...     

增强微孔二氧化硅氢气分离膜疏水性的研究现状

综述了提高微孔二氧化硅膜疏水性的方法以及微孔二氧化硅膜材料在氢气分离方面的应用.孔表面羟基是导致微孔二氧化硅膜亲水的主要原因,因此在溶胶-凝胶反应阶段用疏水基团来修饰溶胶,可以在最终材料的孔表面引入疏水基团,降低羟基浓度,从而提高其疏水性.修饰后的二氧化硅膜孔结构没有显著的变化,可以应用于氢气分离等领域.     

SPA用于丝素膜的生物改性研究

用生长因子RGD半抗原（GLY-ARG-GLY-ASP-SER-PRO-LYS)连接到卵清蛋白Ovalbumin(OVA)载体上诱发出了抗RGD抗体IgG，并用丝素溶液包埋SPA(Staphylo-coccal protein A，简称A蛋白或SPA)制成不溶性SPA丝素膜为材料，然后用诱发出的RGD抗体IgG结合到不溶性SPA丝素膜的表面，制成IgG-SPA丝素膜，再在其上结合粘附生长因子RGD，制成RGD-IgG-SPA丝素膜。利用这一丝素膜培养血管内皮细胞(Vas-cular Endothelial Cell，简称EC细胞)，用四甲基偶氮些盐比色方法(MTT法)检测细胞的生长增殖情况。结果表明，RGD-IgG-SPA丝素膜能有效促进EC细胞的生长。对不溶性SPA丝素膜和IgG以及IgG和RGD之间的生物结合力测定，表明其结合力远大于离解力。同时在细胞培养液中没有检测到丝素膜中SPA的渗漏。RGD-IgG-SPA丝素膜为其作具有的这些优良性质为血管支架打下了基础。     

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.     

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.     

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 ...     

Effect of Oxide Assisted Metal Nanoparticles on Microstructure and Morphology of Gallium oxide Nanowires

Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.     

The Influence of Nitrogen and Boron Implant into Silicon Substrate on the Phase and Internal Stress of c-BN Films

Cubic boron nitride(c-BN) film was deposited on a Si (100) substrate by the RF-magnetron sputtering.The mainly problems for fabrication of c-BN films are the low purity and high intrinsic compressive stress. In order to solve the two problems, the c-BN film with the buffer interlayer was deposited on the substrate which had been implanted with nitrogen and/or boron ions. The results show: the implantation of nitrogen ions can obviously increase c-BN content and reduce the internal stress slightly; while the implantation of boron shows no obvious improvement to the content of c-BN, which can reduce the internal stress in the film obviously. In addition, it is suggested that the implantation of nitrogen and boron shows the best result, which not only can increase the content of c-BN, but also reduce the internal stress in the c-BN film obviously.