磁铁矿/磁黄铁矿复合矿物强化电修复治理Cr(VI)污染性能及含铬产物分析

整合还原固定材料与电修复技术,是增强Cr(VI)污染治理效果的有效方法。利用磁铁矿/磁黄铁矿复合材料构建矿物强化电修复的Cr(VI)治理体系,研究Cr(VI)的去除效果,比较该治理体系与电修复体系的Cr(VI)返溶率,并利用Raman光谱仪、X射线衍射仪、环境扫描电子显微镜及能谱仪对含铬产物进行表征。结果表明:对Cr(VI)含量为350 mg/kg的污染模拟土壤,Cr(VI)去除率近100%,总铬(TCr)去除率可达96%;矿物强化电修复实验组中Cr(VI)返溶率降低54%以上;铬与铁元素的分布相关性高,铬以矿物相的形式稳定存在。实验证明,电修复中整合矿物可以提升铬的去除率并强化铬的矿化。本工作为长效稳定地修复Cr(VI)污染场地提供了新思路。

室温磁电材料的制备与性能

室温下具有磁电性能的多铁性材料是近年来研究的热点,分析了室温铁磁电单相材料和复合材料的制备方法及其性能,特别是外延生长、二次烧结和无机/有机复合技术分别对单相铁磁电薄膜、颗粒弥散型以及层状铁磁电复合材料结构与性能的影响。结果表明,通过诱导晶格变形、消除体系杂相,能获得具有强室温磁电性能的单相磁电材料。通过提高磁性颗粒在复合材料中的分散程度,可以明显增强弥散型磁电复合材料的磁电性能。将磁性和铁电材料进行层状复合,选择合适的外场耦合模式,得到了高磁电耦合系数的复合材料。

某微细粒复合菱-磁铁矿石综合回收研究

针对某铁矿石矿物组成复杂、菱铁矿和磁铁矿共生密切,且磁铁矿嵌布粒度细、分布分散,有害元素硫含量较高等复杂条件。在探索试验的基础上,最终确定阶段磨矿、原矿磁选预富集-细磨反浮选脱硫-磁选-焙烧-磁选的工艺流程,产出以磁性铁为主的高品位铁精矿和以菱铁矿焙烧产物为主的低品位铁精矿。全流程试验获得高品位铁精矿铁品位62.56%、回收率26.38%,中品位铁精矿铁品位55.54%、回收率48.12%的指标。

Substrate temperature dependence of chemical state and magnetoresistance characteristics of Co–TiO2 nanocomposite films

Co−TiO2 nanocomposite films were prepared via magnetron sputtering at various substrate temperatures.The films comprise Co particles dispersed in an amorphous TiO2 matrix and exhibit coexisting ferromagnetic and superparamagnetic properties.When the substrate temperature increases from room temperature to 400℃,Co particles gradually grow,and the degree of Co oxidation significantly decreases.Consequently,the saturation magnetization increases from 0.13 to 0.43 T at the same Co content by increasing the substrate temperature from room temperature to 400℃.At a high substrate temperature,conductive pathways form among some of the clustered Co particles.Thus,resistivity rapidly declines from 1600 to 76μΩ·m.The magnetoresistive characteristic of Co−TiO2 films is achieved even at resistivity of as low as 76μΩ·m.These results reveal that the obtained nanocomposite films have low Co oxidation,high magnetization and magnetoresistance at room temperature.

Porous TiO2-coated Magnetic Core-Shell Nanocomposites：Preparation and Enhanced Photocatalytic Activity

The core-shell structured TiO2/SiO2 @Fe3O4 photocatalysts were prepared using Fe3O4 as magnetic core,tetraethoxysilane（TEOS） as silica source and tetrabutyl titanate（TBOT） as titanium sources.The as-obtained structure was composed of a SiO2@Fe3O4 core and a porous TiO2 shell.The diameter of SiO2@Fe3O4 core was about 205 nm with thickness of porous TiO2 of about 5-6 nm.The 9%TiO2/6%SiO2@Fe3O4 microspheres possess the highest BET surface area and the BJH pore volume,which are 373.5 m2.g-1 and 0.28 cm3.g-1,respectively.The 9%TiO2/6%SiO2@Fe3O4 photocatalyst exhibited an excellent performance for the degradation of methyl orange and methylene blue dyes.Two different dyes were completely decolorized in 60 min under UV irradiation.The photocatalytic activity and the amount of catalyst were almost not decrease after recycling for 6 times by using external magnetic field.

Preparation and characterization of carbonyl iron soft magnetic composites with magnesioferrite insulating coating layer

Spherical carbonyl iron(Fe)powders were coated with magnesioferrite(MgFe2O4)insulating coating layer and then mixed with epoxy-modified silicone resin(ESR).Soft magnetic composites(SMCs)were fabricated by compaction of the coated powders and annealing treatment.Transmission electron microscopy(TEM),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffractometry(XRD)and X-ray photoelectron spectroscopy(XPS)revealed that the MgFe2O4 layer was coated on the surface of the iron powders.The magnetic properties of SMCs were determined using a vibrating sample magnetometer and an auto testing system for magnetic materials.The results showed that the SMCs prepared at 800 MPa and 550℃ exhibited a significant core loss of 167.5 W/kg at 100 kHz and 50 mT.

Effect of Fe_2O_3/SiO_2 ratio on maghemite-silica particulate nanocomposites

Abstract： Maghemite-silica particulate nanocomposites were prepared by modified 2-step sol-gel process. Superparamagnetic maghemite nanoparticles were successfully produced using Massart＇s procedure. Nanocomposites consisting of synthesized maghemite nanoparticles and silica were produced by dispersing the as-synthesized maghemite nanoparticles into the silica particulate form. The system was then heated at 140 ℃for 3 d. A variety of mass ratios of Fe2O3/SiO2 was investigated. Moreover, no surfactant or other unnecessary precursor was involved. The nanocomposites were characterized using XRD, BET and AGM. The XRD diffraction patterns show the reflection corresponding to maghemite nanoparticles and a visible wide band at 20 from 20° to 35° which are the characteristics of the amorphous phase of the silica gel. The patterns also exhibit the presence of only maghemite and SiO2 amorphous phase, which indicates that there is no chemical reaction between the silica particulate gel and maghemite nanoparticles to form other compounds. The calculated crystallite size for encapsulated maghemite nanoparticles is smaller than the as-synthesized maghemite nanoparticles indicating the dissolution of the nanoparticles. Very high surface area is attained for the produced nanocomposites （360-390 m^2/g）. This enhances the sensitivity and the reactivity of the nanocomposites. The shapes of the magnetization curves for nanocomposites are very similar to the as-synthesized maghemite nanoparticles. Superparamagnetic behaviour is exhibited by all samples, indicating that the size of the maghemite nanoparticles is always within the nanometre range. The increase in iron content gives rise to a small particle growth.

A comparison of soft magnetic composites designed from different ferromagnetic powders and phenolic resins

Soft magnetic composites （SMCs） were prepared from three different ferromagnetic powder particles： iron powder ASC 100.29, spherical FeSi particles and vitroperm （Fe73CulNb3Si16B7） flakes. Two types of hybrid organic-inorganic phenolic resins modified with either silica nanoparticles or boron were used to design a thin insulating layer perfect- ly covering the ferromagnetic particles. Fourier transform infrared （FTIR） spectrometry confirmed an incorporation of silica or boron into the polymer matrix, which manifested itself through an improved thermal stability of the hybrid resins verified by thermogravimetric-differential scanning calorimetry （TG-DSC） analysis. The core-shell particles prepared from the ferromagnetic powder particles and the modified hybrid resins were further compacted to the cylindrical and toroidal shapes for the mechanical, electrical and magnetic testing. A uniform distribution of the resin between the ferromagnetic particles was evidenced by scanning electron microscope （SEM） analysis, which was also reflected in a rather high value of the electrical resistivity. A low porosity and extraordinary high values of mechanical hardness and flexural strength were found in SMC consisting of the iron powder and phenolic resin modified with boron. The coercive fields of the prepared samples were comparable with the commercial SMCs.

高性能MnBi永磁合金研究进展

MnBi永磁合金是一种具有很大吸引力的材料,一是MnBi永磁合金有着不同寻常的铁磁性,还有不同与其他磁体的物理性能等特性,同时材料成本低,无稀土添加。MnBi永磁合金具有高温下的磁晶各向异性和与其他磁性材料不同的正矫顽力温度系数,有望成为高温应用下的高性能永磁材料而使得广泛研究者关注。但由于其相的转变过于复杂,制备高性能、高纯度MnBi永磁合金仍有一定的难度。针对MnBi永磁材料的制备工艺、元素的掺杂、复合的永磁材料的薄膜、粉末、块体材料的研究,阐述了高性能MnBi永磁合金的发展状况与最新研究进展,为制备高性能的MnBi永磁材料提供了基础,为实现现代化的生产创造了可能。

Di- and tetranuclear heterometallic CuⅡ-LnⅢ complexes (Ln = Gd and Dy): Synthesis, structure and magnetic properties

Four 3d-4f heterometallic complexes, [CuⅡ-LnⅢ(bpt)2(NO3)3(MeOH)] (Ln = Gd, 1; Dy, 2; bptH = 3,5-bis(pyrid-2-yl)-l,2,4- triazole), [CuⅡ-LnⅢ(μ-OH)2(bpt)4C14 (H2O)2]·6H2O (Ln = Gd, 3; Dy, 4), have been synthesized under solvothermal condi- tions. X-ray structural analyses reveal that 1 and 2 are isostructural while 3 and 4 are isostructural. In each complex, the copper and gadolinium or dysprosium ions are linked by two triazolate bridges and form a CuⅡ-LnⅢ dinuclear unit. The intramolecu- lar Cu-Ln distances are 4.542, 4.525, 4.545 and 4.538 ] for 1, 2, 3 and 4, respectively. Two dinuclear CuLn units are bridged by two OH- groups into the zig-zag tetranuclear {cunzLnm2} structures with the Ln(Ⅲ)...Ln(Ⅲ) distances of 3.742 and 3.684 for 3 and 4, respectively. Magnetic studies show that the antiferromagnetic CulI-Lnm interactions occur in 1 (Jcu = -0,21 cm-1) and 2. The antiferromagnetic interaction occurs in complex 3 with JcuGa = -0.82 cm-1 and JcdGd = --0.065 cm-1, while domi- nant ferromagnetic interaction occurs in complex 4.

Novel nanocomposites based on a strawberry-like gold-coated magnetite （Fe@Au） for protein separation in multiple myeloma serum samples

A new process to produce magnetite partially coated with strawberry-like gold nanoparticles in aqueous media is reported. The fast response to magnetic fields and optical properties of gold nanoparticle-based colloidal systems are the two main advantages of this new Fe@Au nanomaterial. These advantages allow for the use of this new colloidal nanomaterial for various purposes in proteomics and biomedicine, as proteins can bind to the surface, and the surface can also be funcfionalized. As proof-of-concept, the new Fe@Au nanoparticles have been assessed in biomarker discovery as a tool for pre-concentration and separation of proteins from complex proteomes. To this end, sera from healthy people were compared with sera from patients diagnosed with multiple myeloma. The application of this new Fe@Au nanomaterial combined with mass spectrometry has allowed for the identification of 53 proteins, and it has also shown that the heat shock protein HSP75 and the plasma protease C1 inhibitor are potential biomarkers for diagnostics and control of multilvle mveloma vro^ression.

Multifunctional dextran micelles as drug delivery carriers and magnetic resonance imaging probes

Multifunctional nanoparticles combining diagnostic and therapeutic agents into a single platform make cancer theranostics possible and have attracted wide interests in the field. In this study, a multifunctional nanocomposite based on dextran and superparamagnetic iron oxide nanoparticles （SPIO） was prepared for drug delivery and magnetic resonance imaging （MRI）. Amphiphilic dextran was synthesized by grafting stearyl acid onto the carbohydrate backbone, and micelle was formed by the resulted amphiphilic dextran with low critical micelle concentration at 1.8 mg L^-1. Doxorubicin （DOX） and a cluster of the manganese-doped iron oxide nanoparticles （Mn-SPIO） nanocrystals were then coencapsulated successfully inside the core of dextran micelles, resulting in nanocomposites with diameter at about 100 nm. Cell culture experiments demonstrated the potential of these Mn-SPIO/DOX nanocomposites as an effective multifunctional nanoplat- lk）rm for the delivery of anticancer drug DOX with a loading content （DLC） of 16 %. Confocal laser scanning microscopy reveals that the Mn-SPIO/DOX had excellent internalization ability against MCF-7/Adr cells after 2-h labeling compared with flee DOX.HCI. Under a 3.0-T MRI scanner, Mn-SPIO/ DOX nanocomposite-labeled cells in gelatin phantom show much darker images than the control. Their transverse relaxation （T2） rate is also significantly higher than that of the control cells （33.9 versus 2.3 s^-1）. Our result offers an effective strategy to treat MCF-7/Adr at optimized low dosages with imaging capability.

Carboxylate-bridged helical chains based on an azo carboxylate oximate ligand

Two helical one-dimensional complexes [Mnn（MeOH）4][MnlV（L）2]·2MeOH （1） and [Mnm（salen）][Mnm（L）2] （2） （H2L = HON=C（Ph）N=NC6HaCO2H） contain the noninnocent ligand [Mn（L）2]2- and innocent low-spin [Mn（L）2]-. Intrachain anti- ferromagnetic interaction between adjacent manganese syn-anti and anti-anti carboxylate bridges have been high-spin and low-spin Mn（llI） ions in complex 2. ions via the syn-anti carboxylate bridges in complex 1. Alternate found to transmit ferro- and antiferromagnetic coupling between

An inverted triplesalen ligand by a convergent synthesis and its influence on trinuclear Fe_3~Ⅲ complexes

The inverted triplesalen ligand H6feldMe has been synthesized from 2,4,6-triformyl-phloroglucinol and a ketimine salen half-unit in a convergent synthesis. NMR, IR, and UV-vis spectroscopy reveal that this ligand is not in the O-protonated tau- tomer but in the N-protonated tautomer with substantial heteroradialene contribution. This ligand and the conventional triple- salen ligand H6talent-au2 have been used to synthesize the trinuclear Fem complexes [（feldMe）（FeCl）3] and [（talent-Bu2）（FeC1）3], respectively. The molecular structures of these complexes were obtained by single-crystal X-ray diffraction. Two trinuclear Fem complexes of [（feldMe）（FeCl）3] dimerize via two Fe-phenolate bonds, whereas due to steric hindrance no dimerization is observed for [（talent-Bu2）（FeC1）3]. The structural data also reveal some heteroradialene contribution in the trinuclear complexes. Whereas UV-vis and MOlSbauer spectroscopy are not suitable to distinguish between the two complexes, FT-IR spectra show characteristic features due to the different substitution patterns of the conventional and the inverted triplesalen ligands. Another handle is provided by electrochemistry. Whereas both complexes exhibit an irreversible oxidation wave （0.94 V vs. Fc＋/Fc for [（feldMe）（FeC1）3] and 0.84 V vs. Fc~/Fc for [（talent-Bu2）（FeC1）3]）, which is assigned to the oxidation of the central backbone, higher potential oxidations are reversible for [（talent-Bu2）（FeC1）3]） but irreversible for [（feldMe）（FeC1）3]. This is attributed to the reversible oxidation of the terminal phenolates in the di-tert-butyl substituted [（talentBu2）（FeCl）3] in contrast to the mono-methyl-substituted phenolates in [（feld^ae）（FeC1）3]. The magnetic properties of [（talen^-Bu2）（FeC1）3] reveal a very small ferromagnetic coupling with significant zero-field splitting of the Feul S = 5/2 ions. In contrast, the dimerization of two trinu- clear complexes in [（feldMe）（FeCl）3] results in antiferromagnetic interactions between the two phenolate-bridged FeIII ions, which mask the intra-trinuclear interactions transmitted by the central phloroglucinol backbone.

Entropy Generation Analysis in Convective Ferromagnetic Nano Blood Flow Through a Composite Stenosed Arteries with Permeable Wall

The study of heat transfer is of significant importance in many biological and biomedical industry problems.This investigation comprises of the study of entropy generation analysis of the blood flow in the arteries with permeable walls. The convection through the flow is studied with compliments to the entropy generation. Governing problem is formulized and solved for low Reynold's number and long wavelength approximations. Exact analytical solutions have been obtained and are analyzed graphically. It is seen that temperature for pure water is lower as compared to the copper water. It gains magnitude with an increase in the slip parameter.