可注射乙酰化乙二醇壳聚糖/泊洛沙姆复合水凝胶的制备及药物缓释研究EI北大核心CSCD

泊洛沙姆(poloxamer)是一种温敏性聚合物,在浓度为15.0%(质量分数,下同)~30.0%时可形成凝胶。为改善泊洛沙姆在体温下的成胶浓度和药物缓释性能,以泊洛沙姆407为基底,与新型温敏性乙酰化乙二醇壳聚糖复合,制得了温敏性乙酰化乙二醇壳聚糖/泊洛沙姆复合水凝胶。通过傅里叶变换红外光谱(FT-IR)、试管倒置法、旋转流变仪、扫描电子显微镜(SEM)和紫外-可见分光光度计(UV-vis)对乙酰化乙二醇壳聚糖/泊洛沙姆的结构、温敏性、力学性能、微观形貌和体外药物释放性能进行表征。结果表明,乙酰化乙二醇壳聚糖/泊洛沙姆溶液具有热可逆温敏性溶胶-凝胶转变行为。通过控制乙酰化乙二醇壳聚糖/泊洛沙姆的质量比,能够使溶胶-凝胶转变温度处于室温与体温(25~37℃)之间,缩短凝胶化时间(382s),降低泊洛沙姆407在体温下的成胶浓度(6%)。乙酰化乙二醇壳聚糖/泊洛沙姆复合水凝胶具有高度孔隙化的三维结构,其孔径大小处于10~60μm范围内,且表现出较高的力学性能。乙酰化乙二醇壳聚糖/泊洛沙姆复合水凝胶对抗癌药物吉西他滨具有缓释作用,载药凝胶的释药时间可达72 h。乙酰化乙二醇壳聚糖/泊洛沙姆复合水凝胶在可注射药物缓释载体方面具有重要的应用前景。     

温度敏感型PCL-Pluronic-PCL水凝胶的合成与性能

通过泊洛沙姆(Pluronic)引发己内酯(ε-CL)开环反应,合成了一种较低分子量的PCL-Pluronic-PCL多嵌段共聚物,并采用FT-IR和1H-NMR对其结构进行表征。这种PCL-Pluronic-PCL共聚物有良好的水溶性,并且当其水溶液浓度高于临界凝胶浓度(CGC)时,随着温度的变化呈现出凝胶-溶胶转变特性。采用试管法测试共聚物水溶液的凝胶-溶胶转变。该共聚物水凝胶在可注射药物控制释放系统等方面有着广泛的潜在应用价值。     

前端聚合法制备聚N-异丙基丙烯酰胺/碳纳米管复合水凝胶及其性能

用前端聚合法制备了聚(N-异丙基丙烯酰胺)/多壁碳纳米管(PNIPAM/MWCNTS)复合水凝胶,对产物的微观形貌、温敏性、力学性能和释药性能进行了研究。结果表明,PNIPAM/MWCNTS复合水凝胶具有温度敏感性,MWCNTS的加入不影响水凝胶的低临界转变温度,随MWCNTS含量增加,水凝胶吸水能力降低,力学强度显著提高,当MWCNTS的含量由0%增至10%时,水凝胶的压缩强度从88 k Pa增加到666 k Pa。复合水凝胶具有良好的药物缓释性能。     

IPN智能水凝胶药物缓释体系的设计及评价

为研究水凝胶的缓释作用,制备了一种新型pH敏感型互穿网络(IPN)水凝胶药物缓释体系.以天然多糖材料海藻酸钠(SA)和壳聚糖(CS)为原料,利用高碘酸钠氧化SA引入醛基与CS的水溶性衍生物羧化壳聚糖(CMCS)进行化学交联,同时将SA和钙离子进行物理交联,外层再用CS复合凝聚形成聚电解质膜覆盖,从而得到以多种方式交联的具有IPN结构的缓释水凝胶.采用多种方法表征水凝胶的物理化学结构,并探索了复合水凝胶的最佳性能条件,通过溶胀实验和释药测试研究其性能.结果表明,当氧化海藻酸钠(OSA)和CMCS的共混比例为2:3、氯化钙溶液浓度为2％、CS浓度为2％、包膜时间为30 min时,水凝胶的最大溶胀率可以达到33.59.此水凝胶对模型药物牛血清白蛋白(BSA)、吲哚美辛(IDM)有明显缓释作用,说明此复合水凝胶有望开发成一种集多种交联方式为一体的新型药物缓控释系统.     

一种含纳米银的物理交联壳聚糖-泊洛沙姆膜的制备与表征

为了简单方便地制备出一种柔韧性、吸水能力较好的,并具有一定抑菌特性的薄膜,通过调节溶解在稀醋酸溶液中的壳聚糖-泊洛沙姆溶胶pH值的方法,制备出了具有优良抑菌特性、柔韧性与吸水特性的薄膜。薄膜通过物理交联法制备,并进行了力学测试、薄膜断面SEM测试、吸水能力测试以及抑菌圈试验。测试结果显示,所制备的薄膜的拉伸强度和断裂伸长率与泊洛沙姆和甘油的浓度有关。在薄膜的断面SEM测试中发现,泊洛沙姆的加入,会使凝胶断面出现孔洞,孔洞的最大直径10μm。在吸水能力测试中发现,在PBS溶液中,4‰与6‰泊洛沙姆组和2%甘油组具有更好地吸水能力;而在生理盐水溶液中,8‰泊洛沙姆组和2%甘油组具有更好的吸水能力。在抑菌圈试验中,发现不同泊洛沙姆浓度制备出的薄膜基本上均具有明显的抑菌圈。最后,通过综合以上特性,优选出泊洛沙姆和甘油的浓度分别为6‰和2%。由于其制备的方便性、薄膜较好的柔韧性、吸水性,以及有效的抑菌特性,壳聚糖-泊洛沙姆薄膜有望在烧伤治疗、伤口化脓性感染的治疗方面得以应用。     

纳米银/壳聚糖复合水凝胶的原位制备、表征及抗菌性能研究

在壳聚糖/1,2-丙二醇凝胶中采用抗坏血酸原位还原硝酸银生成纳米银,进而通过碱液置换得到具有不同纳米银含量的物理交联的纳米银/壳聚糖复合水凝胶.紫外-可见光谱、X射线衍射图谱和低分辨率TEM照片的结果表明,复合水凝胶内形成了分散良好的纳米银.高分辨率TEM照片结果表明纳米银的直径在20～50nm之间,但其结晶状态并不均一.抗菌性实验证明,纳米银/壳聚糖复合水凝胶对大肠杆菌和金黄色葡萄球菌均有抗菌效果.     

溶胶法原位复合聚乙烯醇/羟基磷灰石水凝胶的结构与性能研究

研究了制备聚乙烯醇(PVA)/羟基磷灰石(HA)复合水凝胶的溶胶法原位复合技术,将无机纳米粉体的溶胶-凝胶合成反应引入高分子基体。对该法制备的复合水凝胶的相结构、微观形貌和拉伸强度进行了分析,并与物理共混法复合水凝胶加以比较。结果表明,溶胶法原位复合可以在富水基体中制备晶相的HA粉体,且粉体粒径小于200nm,分散良好,复合材料的力学性能也有进一步改善。     

壳聚糖/聚乙烯醇/CMK-8复合水凝胶的制备及其对双酚A的吸附性能研究

通过一锅合成法制备了CMK-8粉末，将其与适量的壳聚糖和聚乙烯醇复合制备了壳聚糖/聚乙烯醇/CMK-8复合水凝胶。对其进行扫描电镜(SEM)表征并考察了温度、pH、水凝胶量等因素对该复合水凝胶对双酚A的吸附影响。结果表明：该复合水凝胶表面光滑，内部具有紧密的网络结构，对双酚A具有较大的吸附量。在35.0℃、pH为8.0、水凝胶量为1.0g/L时，该复合水凝胶对双酚A的吸附量达到最大，最大吸附量可以达到75.7mg/g。该复合水凝胶的制作工艺较简单且对双酚A吸附量也很可观，为复合水凝胶在污染物吸附的应用提供了重要的参考价值。     

壳聚糖/SiO2复合涂层的缓释性能研究

为了了解壳聚糖含量对壳聚糖/SiO2复合涂层缓释性能的影响,将氧氟沙星直接溶于壳聚糖醋酸水溶液中,采用溶胶-凝胶法制备了壳聚糖/SiO2复合涂层。通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、原子力显微镜(AFM)、比表面积及孔径分析仪和光学接触角测量仪(OCA)进行结构和表面分析,并对载药复合膜的释放性能进行了研究。结果显示复合涂层具有良好的缓释性能,其缓释周期和释放率受到壳聚糖含量的影响。     

有机/无机纳米复合水凝胶的制备与应用

纳米材料具有直径小、比表面积大以及易于实现表面功能化的优点,受到广泛的关注。与普通水凝胶相比,将无机纳米材料分散在水凝胶中制备的有机/无机纳米复合水凝胶的力学性能、光学性能、热力学性能都有较大提高。主要综述了TiO₂、SiO₂、Fe₃O₄等无机物作为填充剂或交联剂制备纳米复合水凝胶的方法,如共混法、原位法等,并分析了其在环保、医药等领域的应用。     

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.