用仿生自组装法制备的新型生物复合材料及表征

通过仿生自组装法在室温下制备了纳米碳酸化羟基磷灰石/胶原(nCHAC)复合材料,并采用X射线衍射(XRD)、热分析(TGA)和透射电镜(TEM)进行了观察和分析.结果表明,该材料具有与天然骨相同的纳米尺度和胶原蛋白无机相,含有(2.8～14.7)w%的碳酸化HA成分;其显微结构是矿化的胶原纤维束,类似于天然骨的分级结构.揭示了碳酸化HA和胶原含量不同的复合材料中,具有微小差别的自组装单元.碳酸的百分含量影响矿物的晶体尺寸和胶原纤维的组装.因此,nCHAC复合材料是有前途的硬组织修复用材料,其所具有的特殊性能要归功于生物仿生制备出的nCHAC材料有与天然骨类似的成分和类似的微观结构.     

羟基磷灰石/ 胶原类骨仿生复合材料的制备及表征

通过体外模拟天然骨生物矿化和材料自组装的形成机制, 研究制备了类骨羟基磷灰石/ 胶原仿生复合材料并对材料进行了表征。结果表明: 纳米羟基磷灰石均匀分布在胶原基质上并择优取向排列, 该复合材料的成分和微观结构与天然骨类似。      

生物可吸收储存式药物控释载体制备研究

针对骨科疾病治疗中传统的用药方式存在的问题,研究制备了一种生物可吸收靶向式药物控释载体。首先在体外模拟天然骨的生物矿化过程,利用材料的自组装机制合成了羟基磷灰石／胶原类骨仿生复合材料,再采用热致分相／非溶剂抽提成孔技术进一步与聚乳酸复合制备了三维多孔储存式药物控释载体。通过对材料的表征和模型化合物控释实验,结果显示羟基磷灰石／胶原复合材料与天然骨类似,羟基磷灰石／胶原／聚乳酸储存式载体能达到控制释放的目的。     

国家“863”“973”攻关项目“纳米人工骨”获美国专利

经过近两年的审核和考察，由清华大学材料系崔福斋教授课题组研究的纳米人工骨，日前获得美国专利局颁发的专利批准通知，这为拓展海外市场奠定了基础。作为国家“863”、“973”计划支持的攻关项目，纳米人工骨(NB系列纳米晶胶原基骨材料)与原有传统人工骨材料的最大区别在于，修复后的骨头和人体骨完全一样，不会在体内留下植入物。它仿照人类的骨头生成的机理，采用自组装方法制备纳米晶羟基磷灰石／胶原复合的生物硬组织修复材料，使复合材料具有纳米有序结构的天然骨分级和多孔结构。     

孔结构渐变聚己内酯/羟基磷灰石仿生骨材料

为获得具有类似人骨的渐变孔结构、力学性能良好的羟基磷灰石(hydroxyapatite,HA)/聚己内酯(polycaprolactone,PCL)仿生骨材料,采用水热法制备了HA粉末,通过溶剂共混法将其与PCL复合,并采用浇铸/NaCl微粒浸出法制备了多孔状HA/PCL复合材料.通过控制造孔剂NaCl的粒径和用量得到了不同孔径、不同孔隙率的HA/PCL复合材料及具有渐变孔结构的HA/PCL复合材料.利用光学显微镜观察了其孔结构,结果为孔径在100～300μm,最大孔隙率达到80%.同时研究了它们在人体体温附近(37±5)℃的力学性能,结果表明渐变孔结构的HA/PCL复合材料的力学性能较单一孔结构的HA/PCL复合材料有了很大的提高.通过梯度造孔不仅可获得与人骨极为类似的多孔仿生材料,同时还可大幅提高多孔材料的力学性能.     

碳磷灰石的制备和性能研究

羟基磷灰石(HA)被认为是目前最有吸引力的骨组织替代材料,与纯HA相比,碳磷灰石(CHA)在化学组成上更接近于人骨和牙齿等硬组织,且具有更好的生物相容性和更高的骨传导性,因此有望成为新型的骨组织替代材料.综述了目前国内外关于碳磷灰石的研究,主要介绍了CHA中碳酸根的取代类型、机理及制备方法,碳酸根的取代对HA结构及各方面性能的影响,以及碳酸根含量的测定等,并指出仿生法合成CHA及其复合材料是最新的研究热点,也是今后骨植入材料研究中的一个重要方向.     

基于仿生技术的高强度复合材料的研究进展

自然界造物的方式是人们制备高强度复合材料的榜样,自然材料的优异特性可以归结为长期自然进化和自然选择条件下所形成多尺度的多级组装结构。阐述了目前研究较多的仿生技术的特点,挖掘了这几类仿生材料的主要组成成分和多级结构实现高强度的机制,重点论述四大类仿生高强度复合材料:基于植物的仿生复合材料、基于动物的仿生复合材料、基于细菌的仿生复合材料、基于天然矿石的仿生复合材料的制备过程和增强机制的研究;揭示了通过仿生手段实现复合材料高强度的原理,并指出其应用领域和目前研究中存在的问题。     

注射式骨修复多孔复合材料的性能研究

骨缺损在临床上是一种常见现象,通过制备纳米羟基磷灰石/聚酰胺66复合材料粉末,并以纳米羟基磷灰石/聚酰胺66和海藻酸钠的混合粉末作为主要固体成分,以聚乙烯醇水溶液为主要液相,通过混合搅拌制备了注射式骨修复多孔复合材料.通过X射线衍射(XRD)、红外(IR)、扫描电镜(SEM)和透射电镜(TEM)对材料的性能进行表征,表征结果表明制备的注射式骨修复材料中含有与天然骨中相似的无机成分,具有好的生物相容性和生物活性.材料的固化时间与材料的固液比、比表面积和温度等因素有关.通过调整材料的固相、液相比例,可以获得不同固化时间和不同孔隙率的骨修复材料.     

破译人骨组装“密码”“断骨再生”梦想成真

清华材料系崔福斋教授带领的研究团队在人骨修复材料领域取得了突破性的成果,不仅破译了人骨的组装“密码”,而且其研究成果在临床应用中取得了良好的治疗效果,让人类“断骨再生”梦想成真！团队主要研究了胶原分子的自组装与调控钙磷盐晶体生长的机理,并研究了人类骨痂的分级结构。在此基础上,根据仿生的思路,在体外模拟生物矿化和自组装过程,发明了纳米晶磷酸钙胶原基骨修复材料。材料的孔隙率约为80％,     

矿化胶原的组装机理

矿化胶原是骨牙结缔组织中的基本结构单元.从材料学角度认识其组装机理是研发骨牙再生材料的基础和前题.概述了近年来围绕矿化胶原的分级结构和自组装机理的研究进展,以及在此基础上的仿生合成所取得的成果.重点说明目前对胶原生物矿化机理的了解程度以及尚在探索中的重要课题.从这项研究也可看到生物材料,特别是组织工程框架材料和再生医学工程中仿生思路的重要性.     

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.