壳聚糖/聚乳酸复合纳米纤维的制备及抗菌性能研究

采用静电纺丝技术制备聚乳酸(PLA)质量分数为8%的纳米纤维及壳聚糖(CS)与聚乳酸(PLA)质量比为1/5、1/10、1/15、1/20、1/40的复合纳米纤维。借助扫描电子显微镜(SEM)观察和红外光谱(FT-IR)分析,并利用振荡烧瓶法测试抗菌性能。结果表明:CS的含量对纳米纤维的形态影响很大,且PLA与CS能很好地复合;复合纳米纤维对大肠杆菌和金黄色葡萄球菌有良好的抗菌作用,当CS与PLA质量比大于1/10时,对2种菌的抑菌率达90%以上。     

静电纺PLGA/姜黄素复合薄膜的制备及抗凝血研究

为了研究姜黄素的抗凝血性能,采用静电纺丝技术,以生物可降解PLGA为载体制备了PLGA与姜黄素质量比分别为4:1、2:1和3:2的纳米纤维复合薄膜.采用傅里叶变换红外光谱研究了复合薄膜的组成成分,结果显示姜黄素与PLGA的特征峰均出现在复合薄膜的红外图谱中;利用扫描电镜(SEM)及相关分析软件分析了不同质量比时纳米纤维膜的表面形态及直径分布.在实验范围内,复合纳米纤维的平均直径为370～800nm,均匀性较好,且纤维平均直径随姜黄素含量的增加而增大.同时研究了复合薄膜的部分凝血活酶时间(APTT),结果表明,复合薄膜的APTT比原血浆的延长了18s,说明PLGA/姜黄素复合薄膜具有良好的抗凝血性能,且抗凝血性能随姜黄素含量的增加而进一步提高.     

羽毛角蛋白/PVA复合纳米纤维膜的制备及表征

以羽毛角蛋白(FK)和聚乙烯醇(PVA)为原料,水为溶剂,通过静电纺丝技术制备了FK/PVA复合纳米纤维膜.探讨了复合纳米纤维中FK与PVA的相容性,研究了FK的添加对纤维膜微观形貌、结晶度、热稳定性、亲水性等性能的影响.SEM结果表明,在聚合物总质量分数为14％的条件下制备的FK/PVA复合纳米纤维,表面平整光滑,平均直径为250～320 nm,FK含量越大,直径越小.FTIR结果表明,FK与PVA具有良好的相容性,分子间存在氢键作用力.XRD结果表明,FK的加入破坏了PVA分子的规整排列,复合纳米纤维膜的结晶度下降.TG分析与接触角测试结果表明,随着体系中FK配比的增大,复合纳米纤维膜的热稳定性和亲水性均得到提高.     

热塑性聚氨酯纳米粘土复合泡沫结构与性能的研究

要研究了纳米粘土含量对热塑性聚氨酯(TPU)复合泡沫的结构与性能的影响。通过扫描电镜(SEM)观察TPU泡沫的微孔结构发现:随着纳米粘土含量的增加,微孔的直径显著减小且数量明显增加。拉伸测试发现纳米粘土含量增加到5%(质量分数)时,TPU复合泡沫的力学性能增加了56.3%,而复合泡沫的密度却减小了12.5%。研究认为可以通过改变纳米填料的含量,来调节聚合物复合泡沫的微观结构和机械性能,这对微孔聚合物泡沫的工业生产有着重要的指导意义。     

单宁/醋酸复合纳米纤维的制备及抗菌性研究

利用静电纺丝技术制备了质量分数为11％的醋酸纳米纤维以及单宁(TA)质量分数为1％、3％、5％的单宁/醋酸复合纳米纤维膜;采用扫描电镜和傅里叶红外光谱进行了形貌表征和成分分析,用改良的振荡烧瓶法测试了纳米膜的抗菌性能.结果表明:在试验范围内均能制得连续均匀、表面光滑的纳米级纤维;TA的添加对纤维形态有影响,随着添加量的增多,纤维直径和CV值都有所增加;复合纳米膜中存在TA成分,证实了二者能够进行复合,有良好的相容性;单宁/醋酸复合纤维膜对大肠杆菌和金黄色葡萄球菌有优良的抗菌效果,当TA含量仅为1％时,抑菌率就已达到85％以上,TA含量越大,抗菌效果也越显著.     

甲壳素纳米晶须/聚乳酸复合纤维膜的制备及表征

采用静电纺丝技术制备了甲壳素纳米晶须/聚乳酸复合纳米纤维膜并对其进行了表征分析.借助扫描电子显微镜(SEM) 及相关测试软件,测出复合纳米纤维平均直径在500～1000nm之间;当甲壳素纳米晶须含量低于7％时,对复合纳米纤维的可纺性及形貌影响较小;但当其含量高于7％时,复合纳米纤维表面变得粗糙.傅立叶红外变换光谱仪(FT-IR)和X射线衍射仪(XRD)观察分析表明,甲壳素纳米晶须已成功加入到聚乳酸纤维中.拉伸试验结果表明,当纳米晶须含量为3％时,复合膜的拉伸强度提高了63.65％,进一步增加纳米晶须含量,其增强作用呈下降趋势,甚至出现负增强.     

静电纺丝法制备温敏性PNIPAAm/EC复合纳米纤维

采用静电纺丝技术成功制备出温敏性PNIPAAm/EC复合纳米纤维并使用扫描电子显微镜(SEM)、傅里叶变换红外光谱(FT-IR)、凝胶渗透色谱(GPC)及接触角(CA)对复合纤维进行表征。结果表明:制备的复合纳米纤维直径为360~400nm,当纺丝液中聚N-异丙基丙烯酰胺(PNIPAAm)与乙基纤维素(EC)的质量比为1∶2时,纤维形貌最佳,且随着EC含量增加,纤维直径减少;当温度为25℃时,材料表现为较强的亲水性,当温度为40℃时,材料疏水性明显增强。实验结果可以证明PNIPAAm/EC复合纳米纤维具有良好的温敏性能,可应用为温敏性智能型载药材料。     

静电纺丝法ZrO_2/PVDF-PAN超级电容器隔膜的制备及其电化学性能

采用静电纺丝法,以聚偏氟乙烯(PVDF)和聚丙烯腈(PAN)为基体,通过改变ZrO_2的含量,制备了ZrO_2/PVDF-PAN复合纤维膜。用SEM和比表面积测试仪(BET)分别对复合纤维膜的形貌和比表面积进行了表征。结果表明:纳米ZrO_2的加入量对ZrO_2/PVDF-PAN复合纤维膜的形貌有较大影响,随着纳米ZrO_2含量的增加,纤维表面变得凹凸不平,提高了纤维膜的比表面积,进而提高了纤维膜的吸液率,且当ZrO_2含量为PVDF和PAN总质量的0.4%时达到最大值。将复合纤维膜组装成超级电容器,利用电化学工作站对其循环伏安(CV)和交流阻抗(EIS)性能进行测试,研究了ZrO_2的加入对复合纤维膜电化学性能的影响。结果表明:ZrO_2的加入提高了ZrO_2/PVDF-PAN复合纤维膜的电导率,当ZrO_2含量为0.4%时其电化学综合性能最好,其中比容量达126.0F/g,离子电导率为9.31×10~(-3) S/cm。     

电纺PEI/PVP复合纳米纤维的制备与表征

利用静电纺丝技术制备了纳米级别的聚醚酰亚胺(PEI)/聚乙烯吡咯烷酮(PVP)复合纤维,考察了不同的纺丝工艺参数对PEI/PVP纤维形貌的影响。利用扫描电镜对纤维表面进行观察;通过红外光谱分析纤维中复合物间的相互作用;采用示差扫描量热分析(DSC)检测纤维的热性能。实验表明,以二氯甲烷(DCM)和N,N-二甲基乙酰胺(DMAC)为混合溶剂,体积比为5:1～6:1,聚醚酰亚胺与聚乙烯吡咯烷酮重量比为1∶1～1∶5范围内时,静电纺丝高压为12kV,流速为1mL/h时,使用混纺技术可获得表面光滑、粗细均匀的PEI/PVP复合纳米纤维,纤维直径在400～700nm之间。红外光谱和DSC结果表明,聚合物之间通过氢键作用、静电吸引发生相互作用而复合形成纳米纤维,并且复合纤维良好的保持了PEI优异的热稳定性。     

羽毛多肽改性P(MA-AA)纳米纤维膜的制备及其表征

利用静电纺丝技术,制备了P(MA-AA)与羽毛多肽质量比分别为100/0、95/5、90/10、85/15、80/20复合纳米纤维膜。利用红外光谱和扫描电镜(SEM)对复合纳米纤维膜进行表征,分别利用电子强力机和表面张力仪对复合纳米纤维膜力学性能和亲水性能进行测试。SEM图分析表明:加入羽毛多肽后,纤维形貌得到很大改善,纤维的直径随着多肽含量的增加而逐渐减小;复合纳米纤维膜的断裂强度先增加后减小,断裂伸长率由156.5%减小到52.3%;羽毛多肽的加入显著提高了纳米纤维膜的亲水性能。     

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 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.     

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.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.