碳酸盐矿化菌调控碳酸钙结晶动力学、形态学的研究

选用实验室自培育碳酸盐矿化菌,研究了体系、细菌体体系、细菌分泌物液体系对碳酸钙结晶动力学,晶体形貌影响.研究发现细菌液浓度增加,抑制碳酸钙成核动力学"平台区"由0增加到7.8min;细菌体作为异相成核点加速结晶过程;分泌物抑制晶体成核,并随着与Ca2 混合时间的不同,"平台期"延长.球形碳酸钙的产生是由细菌分泌物调控;Ca2 同有机质表面-COO-和CO结合,并且随着相互间作用程度的增加,球状碳酸钙不规整表面逐步转变为光滑表面.本研究对于微生物诱导碳酸钙的工程性应用如混凝土微裂缝修复、古建筑表面防护处理、微纳米碳酸钙颗粒制备等具有一定指导意义.     

用于高频声表面波器件的CVD金刚石衬底的研究

使用纳米金刚石粉研磨工艺预处理硅片衬底抛光面,在低气压成核的条件下,以丙酮和氢气为反应物,采用传统的热丝辅助化学气相沉积法,制备了自支撑金刚石膜;通过射频磁控溅射法沉积氧化锌薄膜在自支撑金刚石膜的成核面,形成氧化锌/自支撑金刚石膜结构.通过光学显微镜、扫描电镜及原子力显微镜测试自支撑金刚石膜成核面的表面形貌.研究结果表明:成核期的低气压有助于提高成核密度,成核面表面粗糙度约为1.5 nm;拉曼光谱显示1334 cm-1附近尖锐的散射峰与金刚石SP3键相对应,成核面含有少量的石墨相,且受到压应力的作用;ZnO/自支撑金刚石膜结构的XRD谱显示,氧化锌薄膜有尖锐的(002)面衍射峰,是c轴择优取向生长的.     

原位沉析羟基磷灰石-壳聚糖骨组织工程支架材料的研制

仿生构建羟基磷灰石-壳聚糖复合材料是制备骨组织修复材料的重要途径之一.本研究利用有机官能团对无机物矿化的调控作用,在壳聚糖多孔支架表面原位沉析羟基磷灰石(HAp).在仿生溶液中,采用简单的化学处理,使HAp晶体在壳聚糖多孔支架表面原位沉析.研究结果表明壳聚糖分子结构中的氨基作为成核位点,在碱性条件下首先与吸附Ca2 ,再通过静电作用力吸附仿生溶液中的PO43-、OH-等其它离子促使HAp晶体在壳聚糖支架材料表面的成核、长大.此类材料有望成为一种生物活性的骨组织工程材料.     

金属间化合物的制备方法

金属间化合物高温下具有很多优异的性能,如高熔点、高硬度等,本文介绍了金属间化合物的几种制备方法,如机械合金化、自蔓延高温合成、放电等离子烧结、等离子表面重熔法等,总结了各方法的特点以及所存在的问题。     

微乳液法制备成核剂对聚丙烯改性的影响

采用微乳液作为成核剂载体将苯甲酸钠加入聚丙烯,研究其对聚丙烯力学性能及结晶行为的影响。将成核剂苯甲酸钠溶解于水中作为水相,与油相Marcol-52、表面活性剂吐温60和助表面活性剂正己醇共混,制备了一种含有苯甲酸钠成核剂的微乳液。将苯甲酸钠微乳液和成核剂粉末分别加入聚丙烯中熔融共混后测试。力学性能、小角X射线散射、偏光显微镜及差示扫描量热仪等结果表明,与苯甲酸钠粉末比较,采用微乳液法将成核剂分散到聚丙烯中,能够使聚丙烯获得更高的取向度、弯曲弹性模量和弯曲强度,而且成核剂能在聚丙烯结晶过程中产生更多的晶核,提高了聚丙烯的结晶度。     

表面活性剂在纳米氧化铝制备中的应用研究

回顾了近年来国内外对于表面活性剂在氧化铝制备过程中的应用研究现状,结合氧化铝制备中中间产物的研究成果,综述了阴离子、阳离子表面活性剂对纳米氧化铝颗粒大小、形貌以及孔结构等的控制作用.分析了吸附机理以及各种因素如表面活性剂物性、溶液pH值、离子强度等对吸附作用的影响.在此基础上探讨了表面活性剂在该领域的应用前景.     

Ce掺杂钛基二氧化锡电极的制备及电催化性能研究

采用高温热氧化法制备了稀土Ce掺杂SnO2/Sb电极,以SEM、EDX、XRD以及XPS等分析方法对所制备电极进行了形貌、组成及结构的表征,并根据Scherrer公式计算了电极表面SnO2的平均晶粒尺寸.结果显示,所制备电极涂层由纳米级的微晶SnO2构成,Ce的掺杂使Sb向电极表面富集,同时Ce本身也有向电极表面富集的趋势;Ce的掺杂影响了SnO2晶粒的成核过程,可能减少了晶格中的氧缺位.对苯酚的电化学氧化降解实验研究表明,Ce的掺杂降低了SnO2/Sb电极对苯酚降解中间产物的降解效率.     

中空纤维膜促进成核的冷却结晶过程

利用中空纤维膜组件的高单位体积换热面积和优异的传热能力,实现膜界面骤冷促进成核,并利用膜界面流场的综合作用力,完成溶液冷却结晶的自动成核和晶种添加功能.以硫脲水溶液作为研究体系,研究PTFE中空纤维膜促进冷却结晶过程.结果表明,利用膜诱导晶核产生的时间为195 s,无膜参与的自发成核冷却结晶诱导时间为280 s.同时,在相同的温度、原料浓度以及搅拌速度下,由于利用膜促进成核的冷却结晶能够有效调控晶种产生的速率和数量并实现自动输送,制备的晶体产品形貌完整、纯度高(99.5%)、平均粒径大(1.35 mm,相比于其他无膜技术提高30%以上)且粒径分布集中.     

负偏压增强金刚石膜与衬底结合强度的理论研究

由于金刚石与Si有较大的晶格失配度和表面能差,利用化学气相沉积(CVD)制备金刚石膜时,金刚石在镜面光滑的Si表面上成核率非常低.而负衬底偏压能够提高金刚石在镜面光滑的Si表面上的成核率,表明金刚石核与Si表面的结合力也得到增强.利用负偏压增强CVD系统制备金刚石膜时,气体辉光放电产生的离子对Si表面轰击,使得Si衬底表面产生了微缺陷(凹坑),增大了金刚石膜与Si衬底的结合面积.本工作主要从理论上研究离子轰击对金刚石膜与Si衬底结合力的影响.     

热致相分离法制备聚偏氟乙烯微孔膜的研究

热致相分离法是一种制备聚合物微孔材料的有效方法.介绍了聚合物初始浓度、稀释剂、降温速率、成核剂、萃取剂等因素对热致相分离法制备聚偏氟乙烯(PVDF)微孔材料的影响,并对热致相分离法制备聚偏氟乙烯(PVDF)微孔膜的最新研究进展进行了介绍.     

纳米磁靶向复合材料的研究进照

纳米磁靶向复合材料将纳米技术和磁靶向技术有机结合起来,借助纳米磁性材料的奇异特性,在肿瘤的磁靶向治疗领域具有很大的应用潜力而备受关注.介绍了纳米磁靶向复合材料的组成、制备及应用于肿瘤磁靶向治疗中的研究进展,并对其发展前景进行了展望.     

纳米复合技术在新型建材中的应用

为了研究纳米材料的基础应用技术,综述了纳米复合技术在研制新型建材中的应用情况,重点介绍了纳米复合技术在新型功能建筑涂料方面的进展,论述了纳米复合技术应用于制备纳米结构型和功能型复合水泥混凝土的进展和思路,并简单讨论了纳米复合技术和纳米复合材料在其他军民领域的应用前景。通过论述认为,纳米复合技术为纳米材料的广泛应用提供了可靠的技术基础和理论指导,也为研制新型建材提供了新的思路。     

纳米巨磁电阻材料的电化学制备及其应用

巨磁电阻材料大多采用物理法制备．与溅射法、分子束外延等方法相比，电化学法具有设备简单、成本低廉、低温操作、过程可控等优势，是制备巨磁电阻材料的良好途径．为此，针对国内外巨磁电阻材料的研究状况，结合多年来本研究室在该领域的研究工作，介绍了一维纳米多层线、二维纳米金属多层膜、自旋阀和颗粒膜等巨磁电阻材料的电化学制备方法、表征及磁电阻性能．简述了巨磁电阻材料在超高灵敏度微型传感器、巨磁电阻磁盘、读出磁头、磁随机存储器和磁电子器件等方面的应用，并对发展前景和研究方向进行了展望．[编者按]     

Core-shell and segmented polymer-metal composite nanostructures

Composite nanostructures (approximately 200 nm wide and several micrometers long) of metal and polyaniline (PANI) in two new variations of core-shell (PANI-Au) and segmented (Au-PANI and Ni-Au-PANI) architectures were fabricated electrochemically within anodized aluminum oxide (AAO) membranes. Control over the structure of these composites (including the length of the gold shells in the core-shell structures) was accomplished by adjusting the time and rate of electrodeposition and the pH of the solution from which the materials were grown. Exposure of the core-shell structures to oxygen plasma removed the PANI and yielded aligned gold nanotubes. In the segmented structures, a self-assembled monolayer (SAM) of thioaniline nucleated the growth of PANI on top of metal nanorods and acted as an adhesion layer between the metal and PANI components.     

浅谈Internet上的材料科技信息资源

为了方便材料研究者和开发者快速检索所需的材料科技信息资源,建立了一个以英文网页为主的搜索引警式的材料科技信息平台,抽样分析了Internet上材料信息资源的分布规律和发展趋势,以满足信息平台分类的需要,综合分析结果表明,当前材料科技信息网站资源正朝着英文化,综合化,商业化方向发展,充分利用本文建立的平台可加快材料工作者信息检索的速度。     

纳米陶瓷粉体的制备

纳米陶瓷是一种新型纳米材料,是现代陶瓷技术发展的最新领域。纳米陶瓷具有一些普通陶瓷所没有的优越性,如高硬度、高韧性、低温超塑性、易加工性等。为了使纳米陶瓷具有优良的性能,必须要有高纯度、化学组成均匀、颗粒大小能满足要求且粒度分布较窄的纳米陶瓷粉体作为原料。本文中主要介绍了纳米陶瓷粉体的制备方法:固相法、液相法和气相法,并分析比较了不同方法的优点与不足。     

Self-assembled hexagonal ordering of Si nanocrystals embedded in SiO(2) nanodots

Highly dense hexagonally ordered two-dimensional arrays of Si nanocrystals embedded in SiO(2)?nanodots were fabricated on a silicon substrate by using a self-assembled porous anodic alumina thin film as a masking layer through which electrochemical oxidation of the Si substrate and ultralow energy Si implantation took place. After removal of the alumina film and high temperature annealing of the samples, hexagonally ordered Si nanocrystals embedded within SiO(2) nanodots were obtained, having sizes in the few tens of nanometer range. The fabricated ordered structures show significant potential for applications either in basic physics experiments or as building blocks for nanoelectronic and nanophotonic devices.     

Nanoporous polymeric materials: A new class of materials with enhanced properties

Nanoporous polymeric materials are porous materials with pore sizes in the nanometer range (i.e., below 200 nm), processed as bulk or film materials, and from a wide set of polymers. Over the last several years, research and development on these novel materials have progressed significantly, because it is believed that the reduction of the pore size to the nanometer range could strongly influence some of the properties of porous polymers, providing unexpected and improved properties compared to conventional porous and microporous polymers and non-porous solids.In this review, the key properties of these nanoporous polymeric materials (mechanical, thermal, dielectric, optical, filtration, sensing, etc.) are analyzed. The experimental and theoretical results obtained up to date related to the structure–property relations are presented. In several sections, in order to present a more compressive approach, the trends obtained for nanoporous polymers are compared to those for metallic and ceramic nanoporous systems. Moreover, some specific characteristics of these materials, such as the consequences of the confinement of both gas and solid phases, are described. Likewise, the main production methods are briefly described. Finally, some of the potential applications of these materials are also discussed in this paper.     

Bionanocomposites: A New Concept of Ecological,Bioinspired, and Functional Hybrid Materials

Bionanocomposites represent an emerging group of nanostructured hybrid materials. They are formed by the combination of natural polymers and inorganic solids and show at least one dimension on the nanometer scale. Similar to conventional nanocomposites, which involve synthetic polymers, these biohybrid materials also exhibit improved structural and functional properties of great interest for different applications. The properties inherent to the biopolymers, that is, biocompatibility and biodegradability, open new prospects for these hybrid materials with special incidence in regenerative medicine and in environmentally friendly materials (green nanocomposites). Research on bionanocomposites can be regarded as a new interdisciplinary field closely related to significant topics such as biomineralization processes, bioinspired materials, and biomimetic systems. The upcoming development of novel bionanocomposites introducing multifunctionality represents a promising research topic that takes advantage of the synergistic assembling of biopolymers with inorganic nanometer‐sized solids.     

Multiple Functionalities of Polyelectrolyte Multilayer Films: New Biomedical Applications

The design of advanced functional materials with nanometer‐ and micrometer‐scale control over their properties is of considerable interest for both fundamental and applied studies because of the many potential applications for these materials in the fields of biomedical materials, tissue engineering, and regenerative medicine. The layer‐by‐layer deposition technique introduced in the early 1990s by Decher, Moehwald, and Lvov is a versatile technique, which has attracted an increasing number of researchers in recent years due to its wide range of advantages for biomedical applications: ease of preparation under “mild” conditions compatible with physiological media, capability of incorporating bioactive molecules, extra‐cellular matrix components and biopolymers in the films, tunable mechanical properties, and spatio‐temporal control over film organization. The last few years have seen a significant increase in reports exploring the possibilities offered by diffusing molecules into films to control their internal structures or design “reservoirs,” as well as control their mechanical properties. Such properties, associated with the chemical properties of films, are particularly important for designing biomedical devices that contain bioactive molecules. In this review, we highlight recent work on designing and controlling film properties at the nanometer and micrometer scales with a view to developing new biomaterial coatings, tissue engineered constructs that could mimic in vivo cellular microenvironments, and stem cell “niches.”