磁力旋流器磁系的磁场分析

设计了一种中心吸附铁化合物的磁力旋流器，利用试验和数值模拟的方法，对比分析了磁力旋流器磁场强度和分离性能。在试验中，简化了磁力旋流器磁系的结构，改变导磁铁片厚度、铁芯结构、磁系结构等参数，分析磁系对含铁化合物的吸附能力。利用数值模拟方法得到磁系的磁场强度，为分离能力预测提供依据。结果表明：磁场强度与导磁铁片的厚度成反比，随着导磁铁片厚度增大，磁场强度减小，磁力旋流器对铁化合物颗粒的吸附能力减弱，试验中导磁铁片的厚度为2mm时分离效果最好；铁棒铁芯磁系与铁管铁芯磁系相比具有更大的磁场强度；挤压式磁系与普通磁系相比具有更大的磁场强度。导磁铁片厚度的增大会使磁系端面漏磁量减少，铁芯侧面漏磁量增大；铁棒铁芯磁系的漏磁量相对较小，挤压式磁系的漏磁相对较小。     

磁屏蔽效应对磁场除垢防垢效果的影响

在磁场除垢防垢应用中,管道材料性质的差异会导致流体介质内部的真实磁场大小与理论值存在一定偏差,即磁屏蔽现象,这会大大影响磁处理效果。因此,采用对照试验方法建立两套装置,研究螺线管缠绕段材料分别为铁管和塑料管时,磁屏蔽效应对磁处理效果的影响。试验结果表明,减小磁屏蔽效应,电子除垢仪的除垢、防垢及缓蚀效果得到了提升。     

Development of high-performance magnetic thin film for high-density magnetic recording

This overview describes our recent study on fabrication processes of high-performance magnetic thin films for high-density magnetic recording. Particularly, it is emphasized that electrochemical processes play significant roles in fabricating the recording heads and media used for the high-density recording. Newly developed electrodeposition methods for fabricating CoNiFe and CoFe soft magnetic thin films with high-saturation magnetic flux density are shown, and the key points for obtaining them are highlighted. It is summarized that the effective seedlayers for the sputter-deposited [Co/Pd]_n multilayered films, which are promising candidates as magnetic recording media with strong perpendicular magnetic anisotropy for the high-density magnetic recording, have been developed. We have recently succeeded in developing the novel electroless deposition methods for the CoNiFe-based soft magnetic underlayers of double-layered perpendicular magnetic recording media and for the patterned medium consisting of CoNiP magnetic nano-dot arrays, which are briefly explained.     

The heating effect of iron-cobalt magnetic nanofluids in an alternating magnetic field: application in magnetic hyperthermia treatment

In this research, FeCo alloy magnetic nanofluids were prepared by reducing iron(III) chloride hexahydrate and cobalt(II) sulfate heptahydrate with sodium borohydride in a water/CTAB/hexanol reverse micelle system for application in magnetic hyperthermia treatment. X-ray diffraction, electron microscopy, selected area electron diffraction, and energy-dispersive analysis indicate the formation of bcc-structured iron-cobalt alloy. Magnetic property assessment of nanoparticles reveals that some samples are single-domain superparamagnetic, while others are single- or multi-domain ferromagnetic. The stability of the magnetic fluids was achieved by using a CTAB/1-butanol surfactant bilayer. Results of Gouy magnetic susceptibility balance experiments indicate good stability of FeCo nanoparticles even after dilution. The inductive properties of corresponding magnetic fluids including temperature rise and specific absorption rate were determined. Results show that with increasing of the nanoparticle size in the single-domain size regime, the generated heat increases, indicating the significant effect of the hysteresis loss. Finally, the central parameter controlling the specific absorption rate of nanoparticles was introduced, the experimental results were compared with those of the Stoner-Wohlfarth model and linear response theory, and the best sample for magnetic hyperthermia treatment was specified.     

Reversible thermoflocculation of magnetic core-shell particles induced by remote magnetic heating

We developed multifunctional magnetic polymer brushes with a tailorable thermoresponsive dispersion behavior that can be activated by AC magnetic fields. Via surface-initiated ATRP, magnetic core-shell nanoparticles are obtained that are composed of nanosized superparamagnetic iron oxide cores and a copolymer shell. The shell consists of oligo(ethylene glycol) methylether methacrylate (OEGMA) and methoxyethyl methacrylate (MEMA) copolymers that show a lower critical solution temperature (LCST) in water.The hybrid structures are easily dispersible in water at room temperature, and show a reversible thermoflocculation at critical temperatures adjustable by the copolymer composition. The phase separation can alternatively be initiated and recorded by magnetic heating caused by magnetic losses in AC fields. This method offers a convenient way for the remote-controlled heating and agglomeration of disperse systems.     

磁性液体的应用

磁性液体是一种特殊的新型纳米功能材料，是由磁性纳米微粒(一般要求小于10m)均匀弥散于某种液体基液中所构成的稳定的胶体体系。磁性纳米微粒和基液浑成一体，因此，具有将磁性和流动性两者合而为一的特性，从而衍生出一系列新颖奇异的性质。本文简要介绍了磁性液体应用领域的最新进展。     

二次表面修饰制备工艺的磁粉对磁性流体的性能提高

通过二次表面修饰技术制备磁粉,来对现有磁粉制备技术进行改进,进而提高现有磁粉的整体性能,并研究二次表面修饰技术制备磁粉对磁粉及磁性流体性能的影响。     

磁屏蔽装置在磁力泵上的应用浅析

本文分析了磁力泵的结构和工作原理,对磁屏蔽装置进行了探讨,该种装置可在不破坏原有磁力泵优点的基础上,解决磁力泵磁泄漏对周围电子仪器产生干扰的问题。因此磁屏蔽装置具有磁泄漏量小、对泵体周围仪表不产生电磁干扰等优点,具有重要应用和推广价值。     

磁性负载纳米TiO_2催化剂的制备与光催化性能

采用溶胶-凝胶法在复合磁性载体上负载纳米二氧化钛膜,得到了易于磁性固液分离的复合光催化剂,运用XRD、BET、SEM等方法表征它的物质性质,并以典型的偶氮染料甲基橙为目标污染物,研究了不同工艺条件下制备的催化剂的光催化剂的活性。结果表明:以钛酸丁酯为原料,采用溶胶-凝胶法在复合载体上负载4次,500℃保温2 h,得到的磁载催化剂活性最高,处理初始浓度为20 mg/L,pH值为7,2 h降解率达到46%,同时此催化剂能够用磁场回收利用。     

磁场强化磁性液体自然对流传热的机理

在重力场中流体密度变化产生自然对流,在磁力场中磁性液体的表观密度随外加磁场强度的变化而明显变化,磁场可以改变磁性液体的自然对流.通过对磁场中的磁性液体的静力学计算和分析,建立一个由均匀磁场和均匀梯度磁场同轴叠加的合成磁场,合成磁场使磁场引起的磁性液体密度变化各处均等,各处的自然对流传热均等,从而使磁性液体的表观密度和自然对流传热系数得以准确测量,由此建立起磁性液体的磁场强度、表观密度、Grashof数之间的关联式.磁场强度的增大使磁性液体表观密度增大,使磁性液体处于超重状态,是磁场强化磁性液体自然对流传热的机理.     

Research progress on magnetic nanoparticles for magnetic induction hyperthermia of malignant tumor

As a new malignant tumor therapy method with low side effect, high safety and efficiency, magnetic induction hyperthermia (MIH) has attracted great attention in recent years. As magnetic induction heating media, magnetic nanoparticles (MNPs) are critical for the development of MIH. For clinical safety, the MNPs need a high heating efficiency to reduce the applied dose, minimizing the risk of side effect. Increasing the saturation magnetization and initial susceptibility, adjusting the magnetocrystalline anisotropy constant and particle size to the optimal values are the effective methods of improving heating efficiency. On the other hand, a suitable Curie temperature is desired to realize the self-regulation of the therapy temperature, avoiding the use of clumsy and expensive temperature monitoring and control devices. Substituting the magnetic ions in tetrahedral (A) site of the spinel ferrite with nonmagnetic ions or magnetic ions with smaller magnetic moments can effectively reduce the superexchange interaction between the A and B (octahedral) sites, decreasing Curie temperature. Yet, the reduction of the Curie temperature by ion doping usually reduces the saturation magnetization, decreasing heating efficiency. Increasing the fraction of heat generated by relaxation loss and increasing the saturation magnetization may be used to improve the heating efficiency.     

Effect of a homogeneous magnetic field on the viscoelastic behavior of magnetic elastomers

Viscoelastic behavior of highly elastic magnetic elastomers has been studied by three different experimental techniques: elongation, static and dynamic shears. It has been shown that the elastic modulus of the materials increases considerably in an external homogeneous magnetic field of up to 0.3 T (100-fold increase of the tangential modulus has been observed at small 1-4% deformations). The appearance of the new effect of pseudo-plasticity induced by the magnetic field has been observed leading to a considerable (up to 100-fold) increase in the shear loss modulus of the composites.     

磁性催化剂反应器耦合磁分离装置

反应磁分离耦合装置兼具化学反应和流固相分离的功能,有助于提高反应效率、降低分离能耗、缩短工艺流程和避免催化剂磨损流失。综述近年来反应磁分离耦合装置的研究进展,流化态耦合磁分离装置包括磁稳流化床反应器和流化床耦合旋流磁分离装置,悬浮态耦合磁分离装置包括磁分离耦合悬浮态光催化反应器和釜式反应器耦合磁分离装置。指出磁性催化剂反应器和磁分离耦合装置应用中需要解决的关键问题是:规范生产适用于磁性催化剂反应器耦合磁分离装置的磁性催化剂以及构建磁性催化剂反应器耦合磁分离装置过程中必须引入磁场发生器。     

磁絮凝膜过滤工艺中附加磁场强化清洗

基于磁强化絮凝膜过滤(MEFMF)工艺中磁絮体和含磁滤饼层的特性,设计了在线(on-line)和离线(off-line)磁强化清洗(MEC)工艺.在磁场和曝气剪切的协同作用下,含磁滤饼层脱离膜纤维表面,膜通量恢复率较常规物理清洗(RC)明显提高.在离线磁强化清洗时,设计反洗装置中心的磁感应强度为6 mT,曝气强度为500 L·m^-2·min^-1,控制清洗时间为5 min,维持反洗压力0.04 MPa,可达到最佳的膜清洗效果,通量恢复率达97%以上.在外加磁场强化清洗过程中,滤饼层中的磁种发生磁化作用,滤饼层表现出微弱的宏观磁性,在磁场的作用下向磁极运动,使得膜通量恢复率明显提高.此外,在MEFMF工艺中采用间歇磁强化清洗,可以更加有效地去除引起不可逆膜污染的胶体和有机物,降低膜污染速率,减缓膜污染.     

Grain growth kinetics and magnetic properties of a V-doped ZnO dilute magnetic oxide

Zn_0.95V_0.05O ceramics, elaborated from milled ZnO and V₂O₅ nanopowders, were sintered at 900, 1000 and 1100 °C for 1, 2, 4, 6, 10 and 14 h. The growth kinetics was studied identifying the grain growth exponent, the activation energy and the pre-exponential factor. The high V₂O₅ concentration allowed a rapid grain growth at 900 °C only at the very first stages (t < 1 h). Meanwhile, at temperatures of 1000 and 1100 °C, the grain growth was extremely fast with a growth exponent of 0.72. The magnetic properties of the samples indicate that ferromagnetism exist in all samples in different magnitudes depending on the sintering conditions. In particular, the maximum magnetization was obtained on the sample sintered at 1100 °C for 14 h, despite the reduction of V concentration. Additionally, secondary paramagnetic phases were detected in the samples sintered at lower temperatures and shorter sintering times.     

Theranostic magnetic nanoparticles

Early detection and treatment of disease is the most important component of a favorable prognosis. Biomedical researchers have thus invested tremendous effort in improving imaging techniques and treatment methods. Over the past decade, concepts and tools derived from nanotechnology have been applied to overcome the problems of conventional techniques for advanced diagnosis and therapy. In particular, advances in nanoparticle technology have created new paradigms for theranostics, which is defined as the combination of therapeutic and diagnostic agents within a single platform. In this Account, we examine the potential advantages and opportunities afforded by magnetic nanoparticles as platform materials for theranostics. We begin with a brief overview of relevant magnetic parameters, such as saturation magnetization, coercivity, and magnetocrystalline anisotropy. Understanding the interplay of these parameters is critical for optimizing magnetic characteristics needed for effective imaging and therapeutics, which include magnetic resonance imaging (MRI) relaxivity, heat emission, and attractive forces. We then discuss approaches to constructing an MRI nanoparticle contrast agent with high sensitivity. We further introduce a new design concept for a fault-free contrast agent, which is a T1 and T2 dual mode hybrid. Important capabilities of magnetic nanoparticles are the external controllability of magnetic heat generation and magnetic attractive forces for the transportation and movement of biological objects. We show that these functions can be utilized not only for therapeutic hyperthermia of cancer but also for controlled release of cancer drugs through the application of an external magnetic field. Additionally, the use of magnetic nanoparticles to drive mechanical forces is demonstrated to be useful for molecular-level cell signaling and for controlling the ultimate fate of the cell. Finally, we show that targeted imaging and therapy are made possible by attaching a variety of imaging and therapeutic components. These added components include therapeutic genes (small interfering RNA, or siRNA), cancer-specific ligands, and optical reporting dyes. The wide range of accessible features of magnetic nanoparticles underscores their potential as the most promising platform material available for theranostics.     

磁性粉煤灰空心微珠表面印迹聚合物选择性识别头孢氨苄

利用共沉淀法制备了粉煤灰空心微珠磁性复合材料（MFACs）,以乙烯基改性的MFACs为基质材料,利用乳液聚合法制备磁性粉煤灰空心微珠表面印迹聚合物（MMIPs）。通过SEM、FT-IR、TGA、XRD和VSM等方法对其物理化学性质进行表征,其比表面积123.65 m²·g^-1,且具有较好的热稳定性、超顺磁性（M_s=12.155 emu·g^-1）。通过系列吸附实验研究表明,Langmuir等温模型能较好地拟合MMIPs对头孢氨苄（cefalexin,CFX）的吸附平衡数据,25℃时MMIPs的单分子层吸附容量为69.55 mg·g^-1。准二级动力学模型能较好地描述MMIPs对CFX吸附动力学行为,选择性实验研究表明,MMIPs对CFX具有较好地选择识别性。结合高效液相色谱分析技术,MMIPs已成功应用于环境样品中痕量CFX的分离/富集。     

磁性生物活性陶瓷的制备

采用溶胶-凝胶法制备前驱体,经高温烧结制备出磁性生物活性陶瓷。利用体外实验方法,结合X射线衍射、扫描电子显微镜和红外光谱分析了材料结构、晶相和生物活性。结果显示,溶胶-凝胶法可制备出微细的非晶态前驱体粉末,经1 050℃烧结的玻璃陶瓷主晶相为β-硅灰石和铁酸钴、磷硅灰石。陶瓷粉末平均粒径为300 nm。烧结的材料在模拟人体血浆浓度的模拟体液中浸泡7 d,在材料表面可生成大量磷灰石,显示出较好的生物活性。     

磁极结构对磁流体密封性能的影响

研究了磁流体密封装置中磁极的组合方式、磁极的级数、磁源的磁场方向和密封间隙对密封性能的影响。实验结果表明,磁流体密封性能随级数的增加和间隙的减小而有所提高,且与磁极组合方式和磁场方向有关