基于磁畴聚合模型的磁记忆效应机理研究

研究了铁磁构件在受载时产生磁记忆效应的机理。结合试件的断裂机制和位错理论,分析了试件组织的微观变化。建立畴壁聚合模型,探讨了构件形成的有取向的宏观磁化。在应力集中区域或微观损伤区域建立带磁偶极子模型,计算试件表面的泄漏磁场。结果表明,畴壁聚合模型可以解释应力集中区域或微观损伤区域的磁场变化。

功能化有机聚合物磁球对金属离子磁固相萃取的研究进展

磁固相萃取(MSPE)借助磁性材料的固有特性,通过磁分离便可实现样液分离,且操作简便快捷,效率高。综述了功能化有机聚合物、离子印迹聚合物、金属有机框架以及有机限进材料功能磁球的制备及其在金属离子MSPE分离富集或去除方面的应用,并对未来的研究方向进行了展望。

分子模拟辅助设计磁敏型分子印迹聚合物的制备及性能研究

结合计算模拟方法和分子印迹技术,采用电子转移反应生成催化剂进行原子转移自由基聚合方法,以二苯并噻吩(DBT)为目标物,设计并制备了一种新型磁敏型分子印迹聚合物(MMIPs)。运用多种表征方法对MMIPs形貌进行了研究,利用气相色谱法研究了MMIPs的吸附性能。结果表明,MMIPs的比表面积和孔体积分别为104.755和0.115 m2/g;MMIPs的饱和磁化强度为19.45 emu/g。采用静态吸附实验研究了MMIPs的吸附动力学、吸附等温线和特异性识别能力。MMIPs的动力学结合特性符合Elovich动力学方程,在298,308和318 K时,MMIPs的平衡吸附容量分别为31.81,36.27和43.13 mg/g。在不同吸附温度下,MMIPs吸附能力随浓度的变化符合Sips等温模型。选择性识别实验表明,在其它结构类似化合物的存在下,MMIPs对DBT具有选择性吸附能力。

磁选柱及其工业应用

介绍了磁选柱结构、分选原理、工业试验和工业生产情况。生产实践表明 ,磁选柱分选低品位磁选精矿 ,在给矿品位 5 0 %～ 6 3%情况下 ,可获得高于 6 5 %～ 6 7%的高品位铁精矿 ,并能简化流程 ,大幅度降低生产成本。工业应用情况表明 。

硬磁软材料的磁致变形数值研究

光滑有限元基于光滑应变技术,在进行数值积分时避免使用等参变换,在模拟软材料大变形问题具有一定的优势。建立了基于光滑应变技术的硬磁软材料大变形模拟的数值格式,给出了数值格式中所需要的应力张量和本构张量。采用该数值格式研究了不同长高比下的硬磁软材料梁在外部磁场激励下的弯曲特性,得到的磁载荷-位移曲线和试验结果进行了对比;模拟了含有不同残余磁场方向分布的硬磁软材料结构在外磁场作用下的形态演化过程,计算的最终变形形态与试验结果进行比较。计算结果表明:采用该数值格式得到的结果与试验结果吻合较好;在不受约束的前提下,硬磁软材料内部残余磁场方向突变处变形较大。研究结果可为由硬磁软材料组成的软体机器人和智能柔性结构的力学分析与变形调控设计提供参考。

Preparation and characterization of composite microspheres of nano zinc ferrite/poly(D,L-lactide-co-alanine)

Magnetic nano zinc ferrite fliuds were synthesized using an improved liquid phase chemical method, which would be used to replace tradditional iron oxides magnetic material. A novel copolymer （PLAA） with D, L-lactide （D, L-LA） and alanine was synthesized using stannous octoate as initiator. Magnetic polymer microspheres were fabricated with nano zinc ferrite fluid coated with alanine modified poly lactide. These as-prepared zinc ferrite fluids, modified poly lactide and magnetic composites, were characterized with X-ray diffraction diffractometer, FT-IR spectrometer, nuclear magnetic resonance spectrometer, scanning electron microscope, transmission electron microscope, vibrating sample magnetometer, and thermogravimetric analyzer. The results demonstrate that the as-prepared zinc ferrite is spinel type of ZnFe2O4 nano crystals with particle size of 20-45 nm and magnetization of 32×10^-3 A.m2. Alanine is copolymerized with lactide, and the prepared composite magnetic microsphere is coated with the modified polylactide, with mass fraction of 45.5% of PLA, particle size ranging from 80-300 nm, and magnetization of 10.6×10^-3 A·m^2, which suggests ZnFe2O4 enjoys a stable magnetization after being coated by polymer.

Immobilization of penicillin G acylase on paramagnetic polymer microspheres with epoxy groups

Paramagnetic polymer microspheres were synthesized by the inverse suspension polymerizationmethod through polymerization of glycidyl methacrylate,ally glycidyl ether and methacrylamide onthe surface of silica‐coated Fe3O4nanoparticles using N,N’‐methylene‐bis(acrylamide)as across‐linking agent.Penicillin G acylase(PGA)was covalently immobilized on the surface of theparamagnetic microspheres by reacting the amino groups of the PGA molecules with the epoxygroups of the paramagnetic polymer microspheres.The effect of the SiO2coating and the amount ofparamagnetic Fe3O4nanoparticles on the initial activity and the operational stability of the immobilizedPGA was investigated.The results indicated that SiO2played an important role in the polymerization process and paramagnetic polymer microspheres with a SiO2‐coated Fe3O4nanoparticles mass content of7.5%are an optimal support material for PGA immobilization.Immobilized PGA on the paramagnetic polymer microspheres shows a high initial activity of430U/g(wet)and retains99%of its initial activity after recycling10times.Furthermore,immobilized PGA exhibits high thermal stability,pH stability and excellent reusability,which can be rapidly recycled by the aid of magnet.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.

Effect of magnetic field on property and structure of polyaniline doped with multiple sulfonic acids

Polyaniline(PAn)doped with multiple sulfonic acid system of dodecylbenzenesulfonic acid(DBSA)and sulfosalicylic acid(SSA)was synthesized by emulsion polymerization using ammonium persulfate(APS)as an oxidizing agent in the presence and the absence of a constant magnetic field(MF)of 0.8 T.The structure and properties of the PAn were characterized by X-ray diffractometer(XRD),thermogravimetric apparatus(TGA),FT-IR spectroscope(FT-IR)and four probe digital multimeter.The results indicate that,when the molar ratio of DBSA to SSA is 1/3,that of dopant to An is 3/2,that of APS to An is 4/5 in the synthesizing media,and the doping time is 3 h,the conductivity of the PAn synthesized in the presence of the MF of 0.8 T reaches 5.88 S/cm,which is higher than that of the PAn synthesized in the absence of the MF.The thermal stability,the crystallinity and the doping degree of the PAn synthesized in the presence of the MF are also improved.MF not only enhances the conductivity,but also reduces the doping time,the dosage of the dopant and the oxidizing agent when the conductivity reaches the maximum.

油船slop舱中油水混合物的分离速度模型

通过分析油船洗舱水中油水重力分离的物理过程 ,建立油滴上浮过程中碰撞聚合后的速度模型 。

Syntheses, Structures and Magnetic Properties of Two Co(II) Coordination Polymers with 2,5-Pyridine Dicarboxylic Acid

The hydro(solvo)thermal reactions of cobalt powder or its chloride with 2,5- pyridine dicarboxylic acid (H2PYDC) yielded two new complexes: [Co(II)2(PYDC)2(H2O)2- (H2O)4]n 1 and {Co(II)[NH2(CH3)2]2(PYDC)2}n 2. It is observed that the reactive solvents result in different connectivity modes of ligand and diverse dimensional extension of crystal structures. The correlation between structure and magnetic property will be discussed in this paper. Crystal data for 1: space group P1, a = 7.0419(17), b = 8.937(2), c = 9.6182(19) ?, α = 91.532(4), β = 99.869(10), γ = 107.889(11)o, V = 565.5(2) ?3, Z = 1, Dc = 1.845 g/cm3, μ = 1.56 mm-1, F(000) = 322 , R = 0.0505 and wR = 0.1580; and those for 2: space group C2/c, a = 14.9075(6), b = 8.2523(3), c = 16.9643(2) ?, β = 100.982(2)o, V = 2048.75(11) ?3, Z = 4, Dc = 1.560 g/cm3, μ = 0.892 mm-1, F(000) = 996, R = 0.0443 and wR = 0.1134.

Single-step synthesis of magnetic chitosan composites and application for chromate(Cr(Ⅵ))removal

Magnetic chitosan composites(Fe3O4@chitosan) were synthesized in one single-step, characterized and applied in Cr(VI) removal from water. With the increase of loading proportion of chitosan, Cr(Ⅵ) adsorption capacity of Fe3O4@chitosan composites increased from 10.771 to 21.040 mg/g. The optimum adsorption capacities of Cr(VI) on Fe3O4@chitosan-3 were found in a pH range of 3.0-5.0. Kinetic study results show that the adsorption process follows pseudo-second-order model, indicating that the rate-limiting step in the adsorption of Cr(Ⅵ) involves chemisorptions. Moreover, FT-IR spectra analysis confirms that the amine and hydroxyl groups of chitosan are predominantly responsible for binding. Results from this work demonstrate that the prepared Fe3O4@chitosan composites possess great potential in Cr(Ⅵ) removal from contaminated water.

Adsorption and degradation of norfloxacin by a novel molecular imprinting magnetic Fenton-like catalyst

In this study,a novel magnetically separable adsorbent,molecular imprinting magnetic γ-Fe_2O_3/crosslinked chitosan composites(MIPs),were prepared by a microemulsion process.Adsorption and Fenton-like oxidative degradation of a model pharmaceutical pollutant norfloxacin(NOR) by using MIPs were investigated.Various characterization methods were used to study the properties of MIPs,and it is suggested that the hydroxyl groups are the main adsorption sites for NOR.MIPs present better selective adsorption for NOR than its reference antibiotic sulfadiazine.The NOR adsorption data can be well fitted by Langmuir isotherm model and pseudosecond-order kinetic model.The optimum pH range for NOR adsorption is 7-10.In addition,the MIP-catalyzed Fenton-like system(MIPs/H_2O_2) exhibits remarkably faster removal rate for NOR than the case of γ-Fe_2O_3/H_2O_2.The result indicates that MIPs will be a good functional material in decontamination of pharmaceutical wastewaters since MIPs can be magnetically recycled after the treatment.

Preparation and Characterization of Non-porous Superparamagnetic Microspheres with Epoxy Groups by Dispersion Polymerization

Non-porous superparamagnetic polymer microspheres with epoxy groups were prepared by dispersion polymerization of glycidyl methacrylate (GMA) in the presence of magnetic iron oxide (Fe3O4) nanoparticles coated with oleic acid. The polymerization was carried out in the ethanol/water medium using polyvinylpyrrolidone (PVP) and 2,2’-azobisisobutyronitrile (AIBN) as stabilizer and initiator, respectively. The magnetic microspheres obtained were characterized with scanning electron microscopy (SEM), vibrating sample magnetometry (VSM) and Fourier transform infrared spectroscopy (FTIR). The results showed that the magnetic microspheres had an average size of-1μm with superparamagnetic characteristics. The saturation magnetization was found to be 4.5emu.g-1. There was abundance of epoxy groups with density of 0.028 mmol·g^-1 in microspheres. The magnetic PGMA microspheres have extensive potential uses in magnetic bioseparation and biotechnology.

PREPARATION OF POLYMER PARTICLES WITH HIGH CONTENT OF MAGNETIC MATERIAL

A method for preparing polymer microspheres with high magnetic content is introduced.First of all,the ferrofluid prepared by co precipitation was treated with ethanol.Then,in the presence of the treated Fe 3O 4 particles,the dispersion polymerization of acrylamide was performed using poly (ethylene glycol) (PEG) as dispersant,AIBN as initiator,and ethanol as dispersing medium.The effects of the dispersing medium,the agitation intensity,the amount and properties of magnetic particles on the polymerization and magnetic content in the polymer microspheres are discussed.Finally,polyacrylamide particles having as high as 32.2% (by weight) magnetic Fe 3O 4 particles were prepared.

Preparation and Characterization of Magnetic Resin Made from Chitosan and Cerium

In this study, the water-based ferromagnetic fluid and magnetic resin made from chitosan and cerium complex （MRCCC） were successfully prepared by using the chemical co-precipitation technique and by the reversed-phase suspension cross-linking polymerization. MRCCC presented uniform and narrow panicle size distribution as determined by the Laser Panicles Sizer. The Inductively Coupled Plasma-Atomic Emission Spectrometry （ICP-AES）, Fourier transform infrared spectroscopy （FT-IR）, differential scanning calorimetry （DSC） and X-ray powder diffraction （XRD） study demonstrated that there were iron and cerium existing in MRCCC. The movement of MRCCC under magnetic field proved its magnetic property. The swelling kinetics in water or solutions with different pH indicated that MRCCC could be applied in solutions with pH greater than 1.0. The ferromagnetic fluid particles were stable in MRCCC soaked in solutions with pH 〉2.0. In view of these results, MRCCC can be used as material for separation, clarification, adsorption, sustained release and hydrolysis activity.

Gd Doped Hollow Nanoscale Coordination Polymers as Multimodal Imaging Agents and a Potential Drug Delivery Carriers

Gd doped hollow nanoscale coordination polymers with multimodal imaging capabilities were synthesized by solvothermal method and further coated by silica layer.The in vitro tests demonstrated uncoated and silica-coated nanoprobes exhibit longitudinal relaxivities(r1)of 7.38 and 13.57(mmol/L)-1·s-1,and transverse relaxivities(r2)of 180.6 and 304.8(mmol/L)-1·s-1,showing fairly good dual T1&T2 contrast effects,and it also emits excellent multicolor uorescence under laser beams of various wavelengths.With the com-bination of magnetic resonance imaging(MRI)(both T1 and T2)and uorescence optical imaging(FOI),the nanoprobes could correlate preoperative diagnosis with intraoperative pathology.Furthermore,it also exhibits high drug loading capacity of 1166 mg/g and en-capsulation efficiency of 83.29%,which makes it a potential platform as drug carriers.The MTT assay demonstrates the moderate toxicity of the NPs,and after the silica coating process,not only the MRI contrast effects but also the biocompatibility have been enhanced.The versatility of the highly integrated systems can make up for the limitations of each imaging modality and exhibit great potentials for cancer theranostics.

Electromagnetic Pump Made in a Hybrid Polymer-Ceramic Technology--Preliminary Results

This paper describes technology of the electromagnetic pump made in a hybrid polymer-ceramic technology. The pumping mechanism is realized with a mutual excitation between an electromagnetic coil and a neodymium magnet bonded to a flexible membrane. A PDMS （poly（dimethylsiloxane）） material was used to manufacture a membrane sufficient for the presented micropump. A fish trap construction is adapted to the ceramic technology. The bonding process of ceramics and polymer, using plasma oxidation method, is described as well. Moreover, a membrane deflection depending on magnet dimensions and applied voltage was measured.

STUDY ON SYNTHESIS AND RELAXIVITY OF PARAMAGNETIC POLYESTER METAL COMPLEXES FOR MRI

Fifteen new polyester ligands were prepared by copolymerndion Of EDTA(ethylenediaminetetraacetic acid ) dianhydride or DTPA (dikthylenetriaminepenlaacetic acid) dianhydrtde and dihydric alcohol or dihydric phenol. Theirparanzagnetic metal complexes were also synthesized. All polyester ligands andmetal complexes were characterized by IHNMR, IR spectra and elemental analyses. Preliminary study showed that the polyester .metal complexes had higher relaxation effectiveness as compared to corresponding small molecular metal complexes.

Brain MRI Segmentation Using KFCM and Chan-Vese Model

To extract region of interests （ROI） in brain magnetic resonance imaging （MRI） with more than two objects and improve the segmentation accuracy, a hybrid model of a kemel-based fuzzy c-means （KFCM） clustering algorithm and Chan-Vese （CV） model for brain MRI segmentation is proposed. The approach consists of two succes- sive stages. Firstly, the KFCM is used to make a coarse segmentation, which achieves the automatic selection of initial contour. Then an improved CV model is utilized to subdivide the image. Fuzzy membership degree from KFCM clus- tering is incorporated into the fidelity term of the 2-phase piecewise constant CV model to obtain accurate multi-object segmentation. Experimental results show that the proposed model has advantages both in accuracy and in robustness to noise in comparison with fuzzy c-means （FCM） clustering, KFCM, and the hybrid model of FCM and CV on brain MRI segmentation.

Preparation of Thin Film Composite Nanofiltration Membrane by Interfacial Polymerization with 3,5-Diaminobenzoylpiperazine and Trimesoyl Chloride

A new aromatic diamine,3,5-diaminobenzoylpiperazine （3,5-DABP）,was synthesized from 3,5-diaminobenzoic acid and 1-formyl piperazine.The structure of 3,5-DABP was identified by FT-IR spectra and 1H NMR spectra.With 3,5-DABP as aqueous monomer and trimesoyl chloride （TMC） as organic monomer,thin film composite （TFC） nanofiltration membranes were prepared by interfacial polymerization technology.The salt rejection order of these TFC membranes is Na2SO4MgSO4MgCl2NaCl.This sequence indicates that the membranes are negatively charged.