共查询到20条相似文献，搜索用时 265 毫秒
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介绍了共混法和插层复合法两种PE纳米塑料的制备方法，纳米粒子填充到PE中表现出良好的力学性能、耐磨性能、加工性能、电学性能、磁性能和热性能．概述了PE纳米塑料的研究进展情况，指出目前聚乙烯纳米塑料的研究、开发和应用还处于起步阶段，有待研究的理论和实际问题还很多，但作为一种重要的新型材料，其应用必将具有广阔的前景。 相似文献
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纳米颗粒材料制备科学与工程基础研究进展 总被引：2，自引：0，他引：2
纳米结构材料一般由纳米颗粒、纳米晶及纳米薄膜等结构组装而成，
其特异性能也取决于这些基本构成单元，因此纳米颗粒的制备在纳米技术领域占有重要地位
。基于“纳米颗粒材料制备科学与工程基础研究”国家自然科学基金重点项目所取得的重要
进展及成果，本文论述了不同结构及组成的纳米颗粒的制备方法及形态控制策略，提出了纳
米颗粒化学制备过程的工程特征及放大策略，分析了纳米颗粒材料表面处理技术及相关理论
问题，对有待开展研究的领域和方向提出了建议。 相似文献
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针对不同条件符合颗粒表征,探讨了影响湿化学法包覆硅灰石4种主要因素,以及影响包覆效果的机理。实验研究了正硅酸乙酯在酸或碱的条件下水解形成硅溶胶,在一定的反应温度下在硅灰石表面凝胶形核,形成纳米二氧化硅的包覆层。实验通过控制反应物的水硅比、反应温度、时间和PH值来制备不同工艺下的复合颗粒,寻找最佳的反应条件。实验得出最佳工艺：水硅比=10,反应温度为50℃,反应时间2h,PH值为5～6。 相似文献
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在磁性Fe3O4纳米粒子存在下,利用烯烃聚合后过渡金属催化剂α-二亚胺钯在温和条件下催化环戊烯原位聚合,通过聚环戊烯(PCP)在磁性纳米粒子表面原位异相成核结晶,成功获得一系列PCP包覆磁性Fe3O4纳米粒子。分别通过X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、热重分析(TGA)、差示扫描量热分析(DSC)、扫描电镜(SEM)和透射电镜(TEM)技术对产物结构进行了表征,结果表明PCP已成功包覆于磁性Fe3O4纳米粒子表面,所得复合型磁性纳米粒子仍具有较好的磁性能。 相似文献
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纳米材料的广泛研究为纳米结构薄膜材料的开发和研究提供了坚实的基础.目前,利用自组装的方法制备类似生物材料的有序纳米结构,技术也已经较为成熟.本文采用聚乙二醇（PEG）作为有机添加剂,通过控制PEG的量,可以制备出更小尺寸和形状的二氧化钛薄膜纳米颗粒膜. 相似文献
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I. Rabias H. Pratsinis G. Drossopoulou M. Fardis T. Maris N. Boukos N. Tsotakos D. Kletsas E. Tsilibary G. Papavassiliou 《Biomicrofluidics》2007,1(4)
Ultrasmall superparamagnetic iron oxide nanoparticles coated with gummic acid have been investigated as possible constituents of aqueous ferrofluids for biomedical applications and especially for MRI contrast agent. The structural characteristics and the size of the nanoparticles have been analyzed as well as the magnetic properties. In order to evaluate any possible capabilities as a contrast agent, the relaxation time, T2, of hydrogen protons in the colloidal solutions of nanoparticles have been measured in order to gain information on the relaxation behavior compared to other MRI contrast agents. The in vitro cytotoxicity of the obtained magnetic nanoparticles of iron oxide coated with gummic acid was investigated by two separate methods (MTT and FACS analysis) and by using three different normal and transformed cell lines. Our results showed that the synthesized nanoparticles had no toxic effect on any of the cell lines used. 相似文献
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Wei Lin Joseph L Kirschvink Greig A Paterson Dennis A Bazylinski Yongxin Pan 《国家科学评论(英文版)》2020,7(2):472
A broad range of organisms, from prokaryotes to higher animals, have the ability to sense and utilize Earth''s geomagnetic field—a behavior known as magnetoreception. Although our knowledge of the physiological mechanisms of magnetoreception has increased substantially over recent decades, the origin of this behavior remains a fundamental question in evolutionary biology. Despite this, there is growing evidence that magnetic iron mineral biosynthesis by prokaryotes may represent the earliest form of biogenic magnetic sensors on Earth. Here, we integrate new data from microbiology, geology and nanotechnology, and propose that initial biomineralization of intracellular iron nanoparticles in early life evolved as a mechanism for mitigating the toxicity of reactive oxygen species (ROS), as ultraviolet radiation and free-iron-generated ROS would have been a major environmental challenge for life on early Earth. This iron-based system could have later been co-opted as a magnetic sensor for magnetoreception in microorganisms, suggesting an origin of microbial magnetoreception as the result of the evolutionary process of exaptation. 相似文献
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Focusing and sorting cells and particles utilizing microfluidic phenomena have been flourishing areas of development in recent years. These processes are largely beneficial in biomedical applications and fundamental studies of cell biology as they provide cost-effective and point-of-care miniaturized diagnostic devices and rare cell enrichment techniques. Due to inherent problems of isolation methods based on the biomarkers and antigens, separation approaches exploiting physical characteristics of cells of interest, such as size, deformability, and electric and magnetic properties, have gained currency in many medical assays. Here, we present an overview of the cell/particle sorting techniques by harnessing intrinsic hydrodynamic effects in microchannels. Our emphasis is on the underlying fluid dynamical mechanisms causing cross stream migration of objects in shear and vortical flows. We also highlight the advantages and drawbacks of each method in terms of throughput, separation efficiency, and cell viability. Finally, we discuss the future research areas for extending the scope of hydrodynamic mechanisms and exploring new physical directions for microfluidic applications. 相似文献
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Ioannis Rabias Danai Tsitrouli Eleni Karakosta Thomas Kehagias Georgios Diamantopoulos Michael Fardis Dimosthenis Stamopoulos Thomas G. Maris Polykarpos Falaras Nikolaos Zouridakis Nikolaos Diamantis Georgios Panayotou Dimitrios A. Verganelakis Garyfalia I. Drossopoulou Effie C. Tsilibari Georgios Papavassiliou 《Biomicrofluidics》2010,4(2)
One of the most significant challenges implementing colloidal magnetic nanoparticles in medicine is the efficient heating of microliter quantities by applying a low frequency alternating magnetic field. The ultimate goal is to accomplish nonsurgically the treatment of millimeter size tumors. Here, we demonstrate the synthesis, characterization, and the in vitro as well as in vivo efficiency of a dextran coated maghemite (γ-Fe2O3) ferrofluid with an exceptional response to magnetic heating. The difference to previous synthetic attempts is the high charge of the dextran coating, which according to our study maintains the colloidal stability and good dispersion of the ferrofluid during the magnetic heating stage. Specifically, in vitro 2 μl of the ferrofluid gives an outstanding temperature rise of 33 °C within 10 min, while in vivo treatment, by infusing 150 μl of the ferrofluid in animal model (rat) glioma tumors, causes an impressive cancer tissue dissolution. 相似文献
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We present the conformal coating of non-spherical magnetic particles in a co-laminar flow
microfluidic system. Whereas in the previous reports spherical particles had been coated with thin
films that formed spheres around the particles; in this article, we show the coating of
non-spherical particles with coating layers that are approximately uniform in thickness. The novelty
of our work is that while liquid-liquid interfacial tension tends to minimize the surface area of
interfaces—for example, to form spherical droplets that encapsulate spherical particles—in our
experiments, the thin film that coats non-spherical particles has a non-minimal interfacial area. We
first make bullet-shaped magnetic microparticles using a stop-flow lithography method that was
previously demonstrated. We then suspend the bullet-shaped microparticles in an aqueous solution and
flow the particle suspension with a co-flow of a non-aqueous mixture. A magnetic field gradient from
a permanent magnet pulls the microparticles in the transverse direction to the fluid flow, until the
particles reach the interface between the immiscible fluids. We observe that upon crossing the
oil-water interface, the microparticles become coated by a thin film of the aqueous fluid. When we
increase the two-fluid interfacial tension by reducing surfactant concentration, we observe that the
particles become trapped at the interface, and we use this observation to extract an approximate
magnetic susceptibility of the manufactured non-spherical microparticles. Finally, using
fluorescence imaging, we confirm the uniformity of the thin film coating along the entire curved
surface of the bullet-shaped particles. To the best of our knowledge, this is the first
demonstration of conformal coating of non-spherical particles using microfluidics. 相似文献
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Definable surface chemistry is essential for many applications of microfluidic polymer systems. However, small cross-section channels with a high surface to volume ratio enhance passive adsorption of molecules that depletes active molecules in solution and contaminates the channel surface. Here, we present a one-step photochemical process to coat the inner surfaces of closed microfluidic channels with a nanometer thick layer of poly(ethylene glycol) (PEG), well known to strongly reduce non-specific adsorption, using only commercially available reagents in an aqueous environment. The coating consists of PEG diacrylate (PEGDA) covalently grafted to polymer surfaces via UV light activation of the water soluble photoinitiator benzoyl benzylamine, a benzophenone derivative. The PEGDA coating was shown to efficiently limit the adsorption of antibodies and other proteins to <5% of the adsorbed amount on uncoated polymer surfaces. The coating could also efficiently suppress the adhesion of mammalian cells as demonstrated using the HT-29 cancer cell line. In a subsequent equivalent process step, protein in aqueous solution could be anchored onto the PEGDA coating in spatially defined patterns with a resolution of <15 μm using an inverted microscope as a projection lithography system. Surface patterns of the cell binding protein fibronectin were photochemically defined inside a closed microfluidic device that was initially homogeneously coated by PEGDA. The resulting fibronectin patterns were shown to greatly improve cell adhesion compared to unexposed areas. This method opens for easy surface modification of closed microfluidic systems through combining a low protein binding PEG-based coating with spatially defined protein patterns of interest. 相似文献
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金属材料的发展与人类文明和进步息息相关。非晶合金材料是一类原子结构长程无序,具有独特优异性能的新型金属材料。近年来,非晶合金材料的研发、相关科学问题的研究、在高新技术领域的应用得到快速发展,并对金属材料的设计和研发、结构材料、绿色节能材料、磁性材料、催化材料、信息材料等领域产生深刻的影响。为此,文章在回顾非晶合金材料研究和研发历史过程的基础上,分析了当前其学科的前沿科学问题、发展方向,以及我国在该领域发展的问题、机遇和挑战,并提出相应的启示和建议,以期为加快新金属材料的发展,特别是在高新技术领域的应用提供管窥之见。 相似文献
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Magnetophoretic manipulation in microsystem using carbonyl iron-polydimethylsiloxane microstructures
Magalie Faivre Renaud Gelszinnis Jér?me Degouttes Nicolas Terrier Charlotte Rivière Rosaria Ferrigno Anne-Laure Deman 《Biomicrofluidics》2014,8(5)
This paper reports the use of a recent composite material, noted hereafter i-PDMS, made of carbonyl iron microparticles mixed in a PolyDiMethylSiloxane (PDMS) matrix, for magnetophoretic functions such as capture and separation of magnetic species. We demonstrated that this composite which combine the advantages of both components, can locally generate high gradients of magnetic field when placed between two permanent magnets. After evaluating the magnetic susceptibility of the material as a function of the doping ratio, we investigated the molding resolution offered by i-PDMS to obtain microstructures of various sizes and shapes. Then, we implemented 500 μm i-PDMS microstructures in a microfluidic channel and studied the influence of flow rate on the deviation and trapping of superparamagnetic beads flowing at the neighborhood of the composite material. We characterized the attraction of the magnetic composite by measuring the distance from the i-PDMS microstructure, at which the beads are either deviated or captured. Finally, we demonstrated the interest of i-PDMS to perform magnetophoretic functions in microsystems for biological applications by performing capture of magnetically labeled cells. 相似文献