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1.
使有磁性的微粒均匀地分散在水里,全部液体就像磁铁那样发挥作用。在这个实验中,要研究不容易凝聚的稳定胶体的制作方法及其性质。这种磁性液体(通常叫做磁性流体)有  相似文献   

2.
磁性壳聚糖-聚丙烯酸微球的制备及表征   总被引:12,自引:0,他引:12  
罗志敏  马秀玲  陈盛  钱伟 《化学通报》2005,68(7):551-554
壳聚糖通过与丙烯酸接枝共聚制得壳聚糖聚丙烯酸悬浮液,在铁磁流体(Fe3O4)与聚乙二醇(分散剂)存在下通过与戊二醛交联,制备了磁性壳聚糖聚丙烯酸微球。用扫描电镜、红外光谱对合成的高分子微球进行形貌观察和结构表征,并进行了元素分析和磁性能测试,研究了磁性微球对牛血清白蛋白(BSA)的吸附效果。结果表明,合成的磁性微球外表呈球形,粒径为100~400nm;当Fe含量为2.47%时,磁性微球的饱和磁化强度约为1.30emug,磁矫顽力为280Oe,磁化率为2.16×10-4(常温下),属于顺磁性材料;其对BSA有较好的吸附效果,饱和吸附量约为400mgg。  相似文献   

3.
分子印迹聚合物与磁性纳米材料结合,制备成磁性分子印迹纳米敏感膜,这样做不仅可以发挥分子印迹聚合材料的优势,而且磁性纳米粒子可有效提高电化学传感器的灵敏度、稳定性以及生物相容性等。近年来将磁性分子印迹纳米敏感膜应用于电化学传感器制备成的磁性分子印迹电化学传感器得到了较快的发展。本文就近5年来磁性分子印迹电化学传感器敏感膜所用的磁性材料、敏感膜制备方法以及磁性分子印迹电化学传感器在环境、食品以及临床方面的应用进行了综述总结。  相似文献   

4.
李巍  杨子煜  侯仰龙  高松 《化学进展》2020,32(10):1437-1451
自旋电子学的研究重点在于同时利用电子的电荷和自旋两个自由度对信息进行处理和存储,其具有运行速度快、存储密度高和能耗低等优势。毫无疑问,发展二维磁性纳米材料的可控合成方法及磁性调控策略,对于新型自旋电子学器件的构筑具有重要的科学意义和应用价值。然而,目前得到的二维磁性纳米材料的种类十分有限,而且合成方法及磁性调控手段相对单一,极大地限制了该领域的发展。本文首先根据磁性的来源,对二维磁性纳米材料进行了分类,介绍了诱导产生的磁性和具有本征磁性的二维纳米材料,然后详细地归纳了二维磁性纳米材料常见的合成方法,如机械剥离法、电化学剥离法、化学气相沉积法以及液相合成方法等。此外,着重总结了二维材料磁性的主要调控手段,最后展望了该领域遇到的瓶颈、未来的研究重点及应用前景。  相似文献   

5.
磁性贵金属纳米颗粒因具有高效的催化性能和可重复利用性而受到广泛关注。本文描述了磁性贵金属纳米颗粒的基本结构,介绍了磁性贵金属催化剂的基本组成部分,概括了磁性贵金属纳米颗粒的制备方法,阐述了国内外磁性贵金属纳米颗粒的创新研究,指出了发展磁性贵金属纳米催化剂亟待解决的问题,并对磁性贵金属纳米颗粒的应用前景进行了展望。  相似文献   

6.
溶液的临界现象   总被引:2,自引:1,他引:1  
自然界中大量物理体系的相变中存在着临界现象.距今120多年前,人们在流体气-液相变的研究中第一次发现了临界态(称为气-液临界点)的存在.1895年,Pierre Curie 在测量镍的磁性状态方程时观察到铁磁体在某一特征温度(后来称为居里点)以下会产生宏观磁矩.Curie 发现在居里点平均磁矩趋于零的方式与二氧化碳在气-液临界点附近气液二相的密度差  相似文献   

7.
磁性聚合物微球作为一种新兴起的复合功能材料,由于具有纳米尺寸、超顺磁性、良好的生物相容性、低毒性诸多优点,受到了人们广泛而深入的研究。本文简要介绍了无机磁性粒子的制备方法和磁性聚合物微球的分类,主要对磁性高分子微球的传统制备方法和涌现新方法新技术进行了阐述,并分析了各种制备磁性聚合物微球方法的优缺点及主要影响因素。除此之外,本文也介绍了磁性聚合物微球近年来最新研究成果及应用领域,并对高分子微球未来发展趋势和存在的问题进行了分析。  相似文献   

8.
高强  冯钰锜 《色谱》2014,32(10):1043-1051
磁性固相萃取是当前对复杂样品中痕量目标物进行有效分离富集的热门技术,功能化磁性微纳米粒子是该技术应用中的关键材料。本文综述了各种已报道的功能化磁性微纳米材料,总结了包括表面嫁接有机小分子、表面包覆碳或无机氧化物、表面嫁接或包覆聚合物、载体表面或孔道内负载磁性纳米粒子、载体骨架内掺入磁性纳米粒子、物理共混法制备磁性功能材料在内的6种功能化方法,并对功能化磁性微纳米材料在食物样品前处理中的应用进行了简要评述。  相似文献   

9.
杜凯  朱艳红  徐辉碧  杨祥良 《化学进展》2011,(11):2287-2298
多功能磁性纳米粒由于其独特的性质而受到广泛的关注。磁性纳米粒可以与荧光探针、生物靶向分子或抗肿瘤药物等相结合实现磁性纳米粒的多功能化,因此在多模式成像、癌症的靶向诊断与治疗中有较好的应用前景。本文介绍了磁性纳米粒的合成以及多功能磁性纳米粒的构建方法,重点介绍了核壳型、哑铃型和组合杂化型三种不同类型多功能磁性纳米粒的合成...  相似文献   

10.
磁性壳聚糖微球是通过一定的方法用壳聚糖将磁性材料包埋而形成的磁性微球,其内核为纳米级的磁性金属微粒,外层为壳聚糖.壳聚糖含有大量的氨基和羟基,使其具有特定的理化性质,由此奠定了壳聚糖的许多生物学特性及加工特性的基础.另一方面,其磁性内核使磁性壳聚糖微球具有很好的顺磁性,利用外加磁场可以很方便地进行分离.因此磁性壳聚糖在固定化酶、污水处理、食品工业和生物医药等方面具有广泛的用途,磁性壳聚糖的制备及应用的相关研究也越来越受到重视.本文作者对磁性壳聚糖微球的制备和应用进行评述.  相似文献   

11.
Ionic magnetic fluid (ferrofluid) is a stable suspension of magnetic nanoparticles in water. Cobalt ferrite nanoparticles are interesting in view of high-density recording storage. The size of the magnetic particles strongly influences the physical properties of the ferrofluids. In this study, we describe the synthesis of ionic magnetic fluid in the presence of tartrate ions. By varying the amount of organic ligands, nanoparticles in a large range of size are obtained: the mean diameter varies from 3 to 10 nm. The effect of tartrate ions on the stability of the ionic magnetic fluid is also studied in relation with the size of the magnetic particles and the amount of adsorbed ligand.  相似文献   

12.
The present work studies Kelvin-Helmholtz waves propagating between two magnetic fluids. The system is composed of two semi-infinite magnetic fluids streaming throughout porous media. The system is influenced by an oblique magnetic field. The solution of the linearized equations of motion under the boundary conditions leads to deriving the Mathieu equation governing the interfacial displacement and having complex coefficients. The stability criteria are discussed theoretically and numerically, from which stability diagrams are obtained. Regions of stability and instability are identified for the magnetic fields versus the wavenumber. It is found that the increase of the fluid density ratio, the fluid velocity ratio, the upper viscosity, and the lower porous permeability play a stabilizing role in the stability behavior in the presence of an oscillating vertical magnetic field or in the presence of an oscillating tangential magnetic field. The increase of the fluid viscosity plays a stabilizing role and can be used to retard the destabilizing influence for the vertical magnetic field. Dual roles are observed for the fluid velocity in the stability criteria. It is found that the field frequency plays against the constant part for the magnetic field.  相似文献   

13.
The density functional theory of inhomogeneous simple fluids is extended to an Ising magnetic fluid in contact with a solid surface, which is subjected to an external uniform or nonuniform magnetic field. The system is described by two coupled integral equations regarding the magnetic moment and fluid density distributions. The dependence of the contact angle that a nanodrop makes with the solid surface on the parameters involved in the magnetic interactions between the molecules of fluid and between the molecules of fluid and an external magnetic field is calculated. For the uniform magnetic field, the contact angle increases with increasing magnetic field, approaching an asymptotic value that depends on the strength of the fluid-fluid magnetic interactions. In the nonuniform field generated by a permanent magnet, the contact angle first increases with increasing magnetic field B(M) and then decreases, with the decrease being almost linear for large values of B(M). The obtained results are in qualitative agreement with the experimental data on the contact angle of magnetic drops on a solid surface available in the literature.  相似文献   

14.
Natural cilia are hairlike microtubule-based structures that are able to move fluid on the micrometer scale using asymmetric motion. In this article, we follow a biomimetic approach to design artificial cilia lining the inner surfaces of microfluidic channels with the goal of propelling fluid. The artificial cilia consist of polymer films filled with superparamagnetic nanoparticles, which can mimic the motion of natural cilia when subjected to a rotating magnetic field. To obtain the magnetic field and associated magnetization local to the cilia, we solve the Maxwell equations, from which the magnetic body moments and forces can be deduced. To obtain the ciliary motion, we solve the dynamic equations of motion, which are then fully coupled to the Navier-Stokes equations that describe the fluid flow around the cilia, thus taking full account of fluid inertial forces. The dimensionless parameters that govern the deformation behavior of the cilia and the associated fluid flow are arrived at using the principle of virtual work. The physical response of the cilia and the fluid flow for different combinations of elastic, fluid viscous, and inertia forces are identified.  相似文献   

15.
合成出了带有反应性基团的铁酞菁单体 ,并实现了与苯乙烯单体在磁流体存在下的分散聚合而得磁性高分子微球 .研究了微球结构、组成 ,测定了其磁响应性和光导性  相似文献   

16.
A velocity and absorption coefficient of sound for magnetic fluid (MF) based on water are studied in the frequency range of 12–132 MHz as a function of the concentration of dispersed phase, the uniform magnetic field, the storage time, and the temperature. The MF dispersed phase consist of magnetite Fe3O4 particles stabilized with sodium oleate. The parameters of sound propagation are measured within temperature interval 0–80°C. Densities of MF and sodium oleate are also measured as a function of temperature. Volume concentrations of magnetic fluid components (water, magnetite, and sodium oleate adsorbed on the surface of magnetic particles) are determined. Densities, heat capacities, coefficients of heat conductivity and thermal expansion of aggregates are estimated. Aggregate size distribution in the studied magnetic fluid is described by the log-normal function. Parameters characterizing the aggregate size distribution are determined and their interpretation is given.  相似文献   

17.
磁性液体的合成及生物医学应用   总被引:6,自引:0,他引:6  
本文综述了纳米磁粉的化学合成及磁性液体的一般制备方法及其磁性、磁流变性和磁熵热效应等在靶向给药、栓塞治疗、温热治疗上的应用。  相似文献   

18.
超顺磁性高分子微球的制备与表征   总被引:18,自引:2,他引:18  
用化学共沉淀方法制备了Fe3O4纳米微粒,并用油酸(十八烯酸)和十二烷基苯磺酸钠为双层表面活性剂进行表面修饰,制备了稳定的水分散性纳米Fe3O4可聚合磁流体.在Fe3O4磁流体存在下,将苯乙烯与甲基丙烯酸通过乳液聚合方法制备了磁性高分子微球.透射电镜研究表明,Fe3O4微粒的平均粒径在10nm左右,乳液聚合形成的磁性高分子微球的粒径平均约为130nm;用超导量子干涉仪对微粒及高分子微球进行了磁性表征,结果表明,合成的Fe3O4纳米微粒以及磁性高分子微球均具有超顺磁性.同时,还用红外光谱及X射线衍射表征了磁性高分子微球的化学成分和晶体结构.用热失重方法测得磁性高分子微球中磁性物质的含量为23.6%.  相似文献   

19.
磁流变液是一种形态和性能受外加磁场控制的新型智能材料。在汽车、建筑、医疗、航空航天多种领域具有重要的应用价值,但磁流变液沉降性问题一直是影响其广泛应用的难题。因此,首先从载液、磁性颗粒和添加剂三方面出发,简要回顾了近几年在磁流变液沉降性方面的研究,指出了影响磁流变液沉降性的因素主要有:载液的粘度、磁性颗粒的形状和尺寸、磁性颗粒与载液之间的密度差、添加剂的种类与添加量等。并给出了有效提高磁流变液沉降性的可行策略,最后从磁流变液的沉降现象与应用方面对沉降性研究进行了展望。  相似文献   

20.
The influence of uniform constant magnetic and electric fields, acting simultaneously, on a magnetic fluid drop is theoretically investigated. The drop is suspended in another magnetic fluid that is immiscible with the former. Both fluids are regarded as incompressible, viscous, weakly electrically conducting, polarizable, and magnetizable. The relative orientation of electric and magnetic intensity vectors is arbitrary. The equation for the surface of the drop is obtained in the approximation of small distortion of the drop. It is shown that the surface is an ellipsoid whose semiaxes can be expressed in terms of the intensity vectors of the electric and magnetic fields. The relations determining the orientation of its principal axes are also obtained. Copyright 2001 Academic Press.  相似文献   

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