共混与同轴静电纺载药纳米纤维的制备、表征及比较

采用共混和同轴静电纺制备了负载盐酸四环素药物的聚乙烯醇-苯乙烯吡啶盐(PVA-SbQ)/玉米醇溶蛋白(Zein)复合纳米纤维,在紫外光照射下得到光交联载药PVA-SbQ/Zein复合纳米纤维。利用扫描电镜(SEM)对不同纤维的形貌和直径分布进行了分析;采用透射电镜(TEM)对不同静电纺丝法制备的纳米纤维结构进行了观察和比较;强力测试表明同轴静电纺丝制备的纳米纤维力学性能更强;傅里叶变换红外光谱(FT-IR)曲线表明载药PVA-SbQ/Zein复合纳米纤维保持了原有的化学功能基团;最后比较了两种方法制备的载药纳米纤维膜的药物释放行为。     

PVA-SbQ/透明质酸复合纳米纤维的制备及表征

以不同质量分数(0%、0.5%、1%、2%)的透明质酸和聚乙烯醇-苯乙烯基吡啶盐缩合物(PVA-SbQ)为原料,通过高压静电纺丝制得PVA-SbQ/透明质酸复合纳米纤维。利用扫描电子显微镜(SEM)观察比较光交联前后复合纳米纤维的形貌特征,采用傅里叶变换红外光谱(FT-IR)测试分析复合纳米纤维膜的化学性质,利用热重分析仪(TGA)表征复合纳米纤维膜的热稳定性能,采用界面张力仪表征复合纳米纤维膜的吸水性能。结果表明,透明质酸的加入使PVA-SbQ/透明质酸复合纳米纤维直径增加,热稳定性降低,吸水性能下降。光交联后,PVA-SbQ/透明质酸复合纳米纤维膜中纤维粗细不均匀,纤维排列更加紧密。该复合材料作为面膜材料的基材具有良好的应用前景。     

静电纺制备负载环丙沙星聚乳酸己内酯纳米纤维膜

静电纺丝可简单有效地制备聚合物纳米纤维。所得纤维具有多孔结构和较高的比表面积,在组织工程、伤口敷料及生物医药等方面具有潜在用途。通过静电纺丝技术,制备载药聚乳酸己内酯(PLCL)纳米纤维膜,载入抗菌型药物环丙沙星,应用于伤口敷料。采用傅里叶红外光谱仪、扫描电子显微镜和接触角等表征手段对载药前后的纳米纤维膜进行表征。扫描电子显微镜观察到纤维膜表面光滑,载药后纤维直径变小。抗菌及药物释放实验表明纤维膜具有抗菌性,在药物释放上可起到缓释效果,此纤维材料有望应用在伤口敷料上。     

CS/PA66复合纳米纤维的静电纺丝制备与药物缓释性研究

采用单一溶剂甲酸溶解壳聚糖(CS)和聚酰胺66(PA66),以静电纺丝的方式成功制得不同质量比的CS/PA66复合纳米纤维,通过红外光谱、扫描电镜等对复合纳米纤维的形貌、结构进行表征。结果证明:采用静电纺丝制得不同CS∶PA66质量配合比CS/PA66复合纳米纤维,纤维直径为40~100nm,纤维分布均匀,具有很好的连续性,增加黏度和电导率能够减小CS/PA66复合纳米纤维直径,提高复合纳米纤维堆叠密集度。CS∶PA66质量配合比为2∶8,CS/PA66复合纤维载药量为20%,释放50h,药物累计释放率最高达到88%,CS/PA66作为载药体系具有较好的药物缓释效果。     

抗菌活性微球与PVA静电纺复合纤维膜的构建与其长效缓释性能研究

姜科药物姜黄素具有消毒杀菌、抗炎抗癌等多重医药作用，是理想的天然药物材料，但是其稳定性较差，吸收率较低，在人体中代谢较快，导致其生物利用度较低。通过反向乳液聚合制备了壳聚糖/姜黄素微球，并利用静电纺丝技术将其与聚乙烯醇(PVA)混纺制备成壳聚糖/姜黄素微球与PVA共混纤维膜。通过红外光谱和扫描电镜(SEM)对得到的纳米纤维膜进行性能表征，并通过调控微球与PVA比例提高纳米纤维膜的力学性能、缓释性能以及抑菌率。结果表明：当微球与PVA质量比为1∶5时，共混纤维膜机械性能最佳；药物累计释放测试结果表明，体外释放时长可达54h,缓释曲线符合Ritger-Peppas模型；抗菌测试结果表明，对于金黄色葡萄球菌，载药纤维膜的抑菌率可达99.9%。     

单取向聚酰亚胺纳米纤维膜及其同质复合薄膜的制备

通过静电纺丝的方法制备了单轴取向的聚酰亚胺(PI)纳米纤维膜,并且采用不同环化温度的纳米纤维膜与聚酰亚胺基体进行复合,制备了一种PI纳米纤维增强PI复合薄膜。通过扫描电子显微镜(SEM)研究了纳米纤维的取向情况,以及纳米纤维膜与其基体的界面粘接情况;采用红外光谱对不同热处理温度PI纳米纤维膜的亚胺化程度进行了表征;并对复合薄膜的力学性能进行了表征。结果表明:通过提高滚筒转速可以得到高度取向结构的纳米纤维膜;纳米纤维膜的环化程度随热处理温度升高而提高;纳米纤维的亚胺化程度越低,其与基体之间的界面粘接性越好,复合薄膜的力学性能越佳。     

聚乳酸/杆菌肽静电纺丝纤维的体外释药研究

为探讨聚乳酸纤维结构形貌对杆菌肽药物的缓慢释放行为及作用机理,通过静电纺丝法制备了聚乳酸/杆菌肽单轴纤维、聚乳酸/杆菌肽串珠和(聚乳酸/杆菌肽)-聚乳酸同轴核-壳纤维等聚乳酸/杆菌肽药物缓释体系,并采用红外光谱法和差热分析法对其化学结构和热性能进行了表征.利用紫外分光光度计法研究了不同载药体系的体外药物释放行为,并探索了不同降解时期载药纤维的质量和形貌变化规律.研究表明:杆菌肽与聚乳酸主要为物理结合;聚乳酸单轴纤维和串珠对杆菌肽的扩散释放机理,属于纯Fick扩散;采用单轴和同轴静电纺丝技术可以获得两种不同释药特性的载药纤维.单轴纤维和串珠能够将药物快速释放,适合抗生素的治疗;同轴纤维中药物受控释放,更适合长期、小剂量的药物释放.     

同轴射流技术制备纳米复合材料研究进展

简要介绍了基于电流体动力学射流技术的静电纺丝和静电喷涂的基本原理和发展过程,重点讨论了两种同轴射流技术——同轴静电纺丝和同轴静电喷涂技术的研究现状,包括纳/微米包囊、壳-芯结构的纳米纤维和中空纳米纤维或纳米管的制备。介绍了该技术在药物释放体系、组织工程支架、载药医用敷料和缝合线等方面的潜在应用前景,并对其未来发展进行了展望。      

新型PVA/PEI/MWCNTs纳米纤维制备及其释药研究

采用高压静电纺丝技术制备聚乙烯醇(PVA)/聚乙烯亚胺(PEI)/多壁碳纳米管(MWCNTs)复合纳米纤维并对其进行表征及释药研究。扫描电子显微镜观察结果表明,按不同质量比的PVA/PEI电纺纤维,当其质量比为75∶25时,纤维形貌最佳;随着MWCNTs的增加,纤维直径呈下降趋势,当MWCNTs含量达到3.0wt%时,纤维中出现串珠,透射电镜结果表明PVA/PEI对MWCNTs具有良好的包裹作用,纳米纤维直径在100nm左右,以酮洛芬为模型药物,制备载药纤维膜并在模拟肠液中考察其体外释放行为。     

醋纤基载药纳米纤维膜制备及药物缓释行为研究

为了提高药物灰黄霉素(GSV)的稳定性,静电纺制得载不同量GSV的醋酸纤维素(CA)/β-环糊精(β-CD)纳米纤维膜。采用扫描电镜(SEM)、傅里叶变换红外光谱(FT-IR)、X射线衍射(XRD)、紫外-可见光(UV-Vis)对载药纤维膜进行表征和分析,结果表明:随着载药量的增加,纤维直径变大,药物能完全包覆在纳米纤维内部,具有较高的热稳定性,药物缓释效果好。制得的醋纤基载药纳米纤维膜的纤维平均直径最高达507nm,经过72h后药物释放率最高达到80%。     

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.