丝素蛋白/ 羟基磷灰石复合材料的制备及性能表征

为了改善羟基磷灰石( HAP) 的脆性和新骨诱导性, 采用共沉淀法合成HAP , 盐溶法制备丝素蛋白(SF) , 在胶体状态下将HAP 和SF 复合得到了SF/ HAP 复合材料。采用扫描电镜(SEM) 、X 射线衍射(XRD) ,傅立叶红外光谱( FIR) 对复合材料结构和化学组成进行了分析, 在模拟体液中检验了复合材料的生物活性, 并对其抗压强度进行了测定。结果表明: HAP 与SF 在纳米尺度进行了复合, 复合材料中SF 主要以β-折叠构象存在,酰胺Ⅴ红外特征峰消失,β-折叠构象的其他峰发生了移动, 表明HAP 与SF 间存在化学结合; 模拟体液中浸泡18 天后, 复合材料表面形成了片层状的HAP ; 与纯的HAP 晶体比较, 复合材料结构稳定, 具有较好生物活性和骨诱导性, 其抗压强度可达63 MPa , 可望成为理想的骨组织替换和工程支架材料。      

非织造多孔丝素蛋白/纳米羟基磷灰石复合支架材料的制备和表征

采用水刺法制备了多孔丝素蛋白(SF)支架,通过原位矿化法制备了纳米羟基磷灰石(HAP)/丝素蛋白复合材料。HAP呈现均匀棒状结构,而没有丝素蛋白支架时HAP仅形成颗粒状结构,这表明蛋白支架可诱导HAP形成均匀棒状结构,这可能是源于丝素蛋白中羧基和溶液中Ca2+的静电作用;丝素蛋白支架起到了复合材料基材和HAP原位生长的高分子模板双重作用。采用红外光谱、X射线衍射和力学性能测试对复合材料的结构性能进行了表征,红外谱图表明,HAP中的PO3-4与SF中的—NH2存在强烈的氢键相互作用,而X射线衍射图谱则表明复合材料中SF的保持了β折叠结构和结晶性能,使得复合材料具有良好的力学性能和多孔性能,有利于成骨细胞在支架上的增殖,同时,该方法制备的复合材料力学性能好,可大面积制备,成本低、制备方便,易于实现工业化,可望广泛用于骨修复支架材料。     

氧化石墨烯/丝素蛋白凝胶结构及其性能研究

目前医用凝胶材料普遍存在力学强度较差及生物降解速度过快等问题。以蚕丝丝素蛋白(SF)凝胶为基础材料,加入氧化石墨烯(GO),并将1-乙基-(3-二甲基氨基丙基)碳二亚胺盐酸盐(EDC)及N-羟基琥珀酰亚胺(NHS)作为交联剂制备SF/GO复合凝胶,旨在改善凝胶材料的力学性能,使其在保证复合凝胶材料应有的力学强度的同时,发挥丝素蛋白、氧化石墨烯的生物学效应及凝胶材料的多孔支架作用。实验结果显示,EDC的加入可以使得SF、GO共混形成稳定、均匀的无规卷曲结构,扫描电镜(SEM)显示SF/GO凝胶具有典型的多孔结构。GO的加入可以有效缩短复合材料的凝胶时间,同时复合凝胶材料的力学性能得到明显改善,其压缩强度提高40%以上。GO的加入还可明显延长材料的降解时间。基于SF/GO的复合凝胶在组织修复及再生领域具有较好的应用前景。     

丝素蛋白在室温离子液体中的溶解与再生性能研究

室温离子液体1-烯丙基-3-甲基氯代咪唑和1-(2-羟乙基)-3-甲基氯代咪唑是丝素蛋白的新型良溶剂.丝素蛋白在1-烯丙基-3-甲基氯代咪唑和1-(2-羟乙基)-3-甲基氯代咪唑中的溶解度分别为14.5%(质量分数)(100℃)和8.0%(质量分数)(80℃).向离子液体丝素溶液中加入乙醇或正丁醇可获得再生丝素蛋白.XRD和FT-Raman研究表明再生丝素蛋白膜的构象主要是β-折叠结构.TGA数据表明再生丝素蛋白的热稳定性比天然丝素纤维有所降低,热失重残留物有所增加.同时,机械性能和溶失率分析结果显示从离子液体中再生的丝素蛋白表现出良好的湿态机械性能和优异的稳定性.     

丝素蛋白/纳米生物玻璃复合多孔支架的结构与性能

采用冷冻干燥法制备了丝素蛋白(SF)/纳米生物玻璃(NBG)复合多孔支架材料。并用XRD、FT-IR、SEM等对SF/NBG复合支架进行了结构与性能表征。结果表明,SF/NBG复合多孔支架孔连通性较好,孔径为150～300μm,孔隙率为80.6%～90.3%;同时NBG的加入促进了复合多孔支架中SF的构象部分由无规卷曲向β-折叠转变。复合多孔支架抗压强度和抗压模量相比于纯SF多孔支架有较大提高。采用模拟体液浸泡实验研究了复合支架的体外生物活性,并用XRD、FT-IR和FESEM对试样表面进行了表征。结果显示,复合多孔支架经模拟体液浸泡7d后,表面沉积出类骨羟基磷灰石(HA)层,NBG的加入能加快复合多孔支架表面沉积类骨HA的速度。研究结果显示SF/NBG复合多孔支架材料有望作为生物活性良好的骨组织修复材料。     

PBS-SF核-壳结构复合超细纤维膜的制备及性能

利用同轴静电纺丝方法, 制备聚丁二酸丁二酯(PBS)-丝素蛋白(SF)核-壳结构复合超细纤维膜, 并对复合超细纤维膜进行FE-SEM、 TEM形态表征, 分析了内层纺丝流率对纤维形貌的影响; 通过FTIR和XRD测试, 比较了甲醇处理前后复合超细纤维膜分子结构和结晶性能的变化, 并进行力学性能测试。结果表明: 通过对纤维核层PBS、 壳层SF和横截面的观察, 复合超细纤维有明显的核-壳结构, 可以清晰看出纤维的核层PBS和壳层SF; 随着核层纺丝流率的增大, 超细纤维的平均直径增大; 甲醇处理后, 复合超细纤维膜中壳层SF分子结构由无规构象转变为β-折叠构象, 复合超细纤维膜核层衍射吸收强度减小, 但整个核-壳结构复合超细纤维膜结晶性能无明显变化; 甲醇处理后拉伸破坏应力从14.9 MPa增大到17.2 MPa, 但拉伸破坏应变从96.8%减小到81.8%。      

纳米羟基磷灰石／丝素蛋白生物复合材料的制备和表征

采用硝酸钙-丝素蛋白溶液与磷酸钠原位合成纳米羟基磷灰石(HA),在反应过程中丝蛋白(SF)诱导HA晶体生长,仿生合成HA/SF复合材料,用TEM、IR、TGA、XRD和SEM进行表征。结果表明,HA为CO23-部分替代型,粒径为10 nm~40 nm之间的弱结晶类骨晶体,在形貌和结晶度等方面与人体骨磷灰石相似。HA/SF复合材料中丝蛋白的含量约为25%,HA和SF两相存在强烈化学键合作用。SEM观察结果表明,HA微粒被SF完全包裹,两者之间没有明显相分离。     

羟基磷灰石/丝素蛋白复合材料的制备

以蚕丝丝素蛋白(SF)作为羟基磷灰石(HA)沉积的模板,制备HA/SF复合粉末,用扫描电镜(SEM)、热重分析(TGA)、X射线衍射(XRD)和傅立叶变换红外光谱(FT-IR)对复合粉末进行分析和鉴定。结果表明,合成产物是HA/SF复合物,其平均粒径约为275.7 nm,其中丝素蛋白含量为17.8%(质量分数)。复合粉末经等静压成型后能够制得弯曲和压缩强度分别为19.87 M Pa和28.65 M Pa的HA/SF复合材料,以N aC l为致孔剂能够制得平均孔径约为61μm、孔隙率为40%的多孔HA/SF复合材料。     

不同剪切速率下高浓度再生丝素蛋白水溶液性质与结构的研究

主要研究了不同剪切速率下,丝素蛋白浓度、pH值、钙离子和丝胶含量对高浓度再生丝素蛋白水溶液性质的影响,并采用偏光显微镜和拉曼光谱对剪切前后的溶液结构进行了观察分析.结果表明,高浓度再生丝素蛋白水溶液经过一定的剪切作用后呈现出各向异性的特点,且随着各种因素的调节,溶液出现各向异性的临界剪切速率也随之改变.同时,在一定的剪切条件下,高浓度再生丝素蛋白水溶液中的丝素蛋白分子可发生由无规卷曲向α-螺旋构象的转变,并有进一步形成β-折叠构象的趋势.     

丝素蛋白含量对纳米羟基磷灰石仿生矿化和体外细胞相容性的影响

通过制备含有不同丝素蛋白(SF)含量的丝素蛋白/纳米羟基磷灰石复合材料, 着重研究丝素蛋白含量对纳米羟基磷灰石(n-HA)仿生矿化过程中晶体成核与生长及体外细胞相容性的影响. 结果表明: SF的加入对n-HA晶体的成核和生长具有明显的调控作用; 丝素含量的大小对n-HA晶体成核和生长没有明显的区别, 但对晶粒在有机大分子中的聚集状态有明显的影响: 当SF含量不超过20wt%时, n-HA晶粒呈现放射状团簇, 当SF含量超过20wt%时, n-HA晶粒无序团聚. 体外细胞相容性结果显示, SF的加入可以促进材料与细胞的界面亲和性, 但SF含量对这种亲和性的影响不明显, 20wt%和30wt%的SF含量对增殖能力具有较强的促进作用.     

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.     

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.