负载对苯二酚的聚苯乙烯-二乙烯苯交联微球的制备及缓释行为(英文)

采用超声波改进的二步种子溶胀法制备粒径2.4～9μm的多孔聚苯乙烯-二乙烯苯微球,单分散的聚苯乙烯微球由分散聚合制备并以其作为种球。论文考察了种球类型、超声分散时间、种球和溶胀剂以及交联单体比率等因素对多孔微球形貌及孔结构的影响,并采用扫描电镜、BET等手段对微球性能进行了表征。研究发现超声辅助分散的引入可使产物的粒径分布更窄并将第一步溶胀时间由传统的24h缩短至10h。实验结果表明:种球的单分散性对最终产物的形貌有决定性影响,它的任何形貌缺陷都将在最终产物中被扩大;随着溶胀剂/种球比率和交联单体/种球比率的增加,最终产物的粒径和比表面积增大,孔径减小。以对苯二酚为模型组分,考察其在制得的多孔微球上的缓释行为,发现制得的多孔聚合物微球在用作化妆品活性组分载体时,表现出良好的缓释性能。     

种子聚合法制备单分散交联聚苯乙烯微球的研究

用无皂乳液聚合法合成了直径大于２μｍ的聚苯乙烯种子，合成的种子先用小分子化合物溶胀，再用单体溶胀后聚合，得到了直径为４～８μｍ的单分散交联聚苯乙烯／二乙烯苯微球。研究了甲醇浓度和苯乙烯浓度对种子直径的影响以及小分子化合物的种类和用量、溶胀温度和时间、溶胀剂用量等对生成的微球的直径和分散度的影响。     

基于微流控技术合成单分散聚丙烯酰胺微球

采用T型微流控芯片产生单分散液滴技术制备了尺寸均匀的交联聚丙烯酰胺(PAM)水凝胶微球,考察了芯片中分散相和连续相压力与液滴尺寸的关系,以及丙烯酰胺单体、交联剂和引发剂用量对PAM水凝胶溶胀能力的影响。结果表明,通过调节芯片中连续相和分散相的压力可以获得直径为5~25μm的单分散液滴;PAM微球的体积溶胀能力随引发剂量增加而增强,随单体或交联剂量增加而减弱;当交联剂加入量为单体质量的0.06%时,PAM微球在水中溶胀后的体积是干燥状态下的40倍;交联剂可实现大范围调控PAM水凝胶微球的溶胀能力。     

多孔聚合物微球成孔技术的最新研究进展

综述了多孔聚合物微球的制备方法及成孔机理。种子溶胀法和微膜乳化法用于制备具有微孔、中孔结构的单分散聚合物微球;而大孔聚合物微球的制备通常采用传统的悬浮聚合,并通过后交联法改善其孔性能,提高其比表面积。     

羧基化单分散交联微孔聚苯乙烯微球的制备

以苯乙烯为主单体,丙烯酸为功能单体,二乙烯基苯(DVB)为交联剂,偶氮二异丁腈为引发剂,乙腈和甲苯为溶剂,采用回流沉淀聚合法合成了单分散羧基化交联聚苯乙烯微球;然后以1,2-二氯乙烷为溶胀剂,二甲氧基甲烷为外交联剂,在三氯化铁的催化下发生傅-克超交联反应,实现微孔化。采用傅里叶变换红外光谱、扫描电子显微镜、激光粒度及Zeta电位、比表面积及孔隙分析对微球结构进行了表征。结果表明,通过实验可以得到具有良好球形形貌和单分散性的交联微孔聚苯乙烯微球;随着丙烯酸含量增加,交联微球的带电量增加;随着DVB含量的增加,实现了微孔化且比表面积呈上升趋势,其中当DVB用量为60%时,其比表面积达到606.06 m2/g。     

静电喷雾法制备壳聚糖/康普瑞丁载药微球

本研究采用静电喷雾法,以壳聚糖为基质材料,康普瑞丁为模型药物制备微球。实验中采用AcOH/H2O和AcOH/H2O/EtOH两种溶剂,分析了微球形貌和粒径分布的影响因素,并且对CS-CA4微球的缓释性能进行了测定。结果表明,壳聚糖浓度、溶剂配比及乙醇和康普瑞丁的加入会使壳聚糖微球呈球状、中间塌陷的类球状、棒状等不同形貌,微球粒径存在较大差异;通过AcOH/H2O/EtOH复合溶剂将疏水性药物康普瑞丁载入壳聚糖微球,制备出的壳聚糖/康普瑞丁载药微球分散性好,粒径分布均匀,平均粒径仅为0.27μm;使用戊二醛蒸汽交联48h的微球缓释效果明显。     

多孔羟基磷灰石微球的药物缓释性能

用锂钙硼（LCB）玻璃在磷酸盐溶液中的原位转化反应制备多孔羟基磷灰石（HA）微球,表征微球的物相组成、孔结构和形貌,以溶菌酶为药物模型研究了药物的缓释性能。结果表明,所制备的HA微球具有较好的孔结构。当溶菌酶溶液的浓度较低时,HA微球将溶菌酶吸附在微球的外表面;当浓度较高时,更多的溶菌酶扩散进入HA微球的微孔中,使缓释...     

预交联法制备海藻酸钠复合微球及其缓释性能

采用预交联法制备海藻酸钠(SA)/凹土(ATP)复合微球(PCM)以克服常规制备方法导致微球交联不均匀的缺陷,从而改善微球的缓释性能。将ATP先与Ca~(2+)进行部分离子交换制备Ca~(2+)-ATP,然后在与SA复合过程中同时进行预交联形成交联密度有所提高的微球内核,再采用滴注法制备该复合微球。利用红外光谱、扫描电镜和电子照片对微球结构和形貌进行表征,考察了Ca~(2+)浓度对PCM力学强度、溶胀率、载药和缓释性能的影响。结果表明,PCM在1h的累计释放率由预交联前的68%降为50%,显著改善了微球的"突释"。释放动力学研究表明,微球的释药可用Ritger-Peppas方程很好地拟合,释药速率受骨架溶蚀和药物扩散双重控制。     

壳聚糖微球的制备及其对防污剂Sea-Nine 211缓释性能的研究

采用乳化交联法中的复乳法(o/w/o型)制备负载Sea-Nine 211的壳聚糖(CS)微球,并用扫描电镜和红外光谱对其结构及形貌进行了表征。应用正交试验设计,考察了壳聚糖浓度、投料比、交联剂浓度对微球制备的影响。载有疏水性防污剂Sea-Nine 211的壳聚糖微球的包覆率和缓释性能都比较良好,缓释的防污剂对海洋硅藻三角褐指藻的生长有抑制作用。     

壳聚糖微球的制备及其对防污剂Sea-Nine 211缓释性能的研究

采用乳化交联法中的复乳法(o/w/o型)制备负载Sea-Nine 211的壳聚糖(CS)微球,并用扫描电镜和红外光谱对其结构及形貌进行了表征。应用正交试验设计,考察了壳聚糖浓度、投料比、交联剂浓度对微球制备的影响。载有疏水性防污剂Sea-Nine 211的壳聚糖微球的包覆率和缓释性能都比较良好,缓释的防污剂对海洋硅藻三角褐指藻的生长有抑制作用。     

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.……     

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.     

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.     

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.