Saturation Magnetization Intensity Research Articles

Mono-Sized Anion-Exchange Magnetic Microspheres for Protein Adsorption.

In this study, mono-sized anion-exchange microspheres with polyglycidylmethacrylate were engineered and processed to introduce magnetic granules by penetration–deposition approaches. The obtained magnetic microspheres showed a uniform particle diameter of 1.235 μm in average and a good spherical shape with a saturation magnetic intensity of 12.48 emu/g by VSM and 12% magnetite content by TGA. The magnetic microspheres showed no cytotoxicity when the concentration was below 10 μg/mg. The magnetic microspheres possess respective adsorption capacity for three proteins including Bovine albumin, Hemoglobin from bovine blood, and Cytochrome C. These magnetic microspheres are also potential biomaterials as targeting medicine carriers or protein separation carriers at low concentration.

Electromagnetic and mechanical properties of FA-GBFS geopolymer composite used for induction heating of airport pavement

A soft magnetic layer in the airport pavement can shape magnetic field and improve the induction heating efficiency. During the preparation of soft magnetic material, binder matrix material is mixed with magnetic susceptible inclusions such as iron powders, resulting in the high magnetic and mechanical performances of the soft magnetic layer. Geopolymer, which shows high cohesion strength as well as little environmental impact, appears to be a promising binder candidate. The motivation of this work is to unveil the formation mechanisms of electromagnetic and mechanical properties of FA-GBFS geopolymer composite from the perspective of initial SiO2/Al2O3 molar ratio, so as to provide a theoretical basis for the design of geopolymer-based soft magnetic layer. Results show that the magnetic properties of FA-GBFS geopolymer composite are mainly generated by the Na+ movement. Both geopolymer reaction and calcium silicate hydration reaction exist within the FA-GBFS geopolymer composite, and the synergy of the two chemical reactions determines the electromagnetic and mechanical properties of the FA-GBFS geopolymer composite. Besides, the optimized FA-GBFS geopolymer composite can not only present a saturation magnetization intensity up to 25 times that of cement, but also meet the mechanical requirement of airport pavement.

Symmetrically Controlled Design of Twin Alumina-Co Composite Thin Films

Self-assembled dual-working electrode electrolytic cells were designed to produce twin alumina-Co composite films with highly symmetrical microstructures using a deflected electric field-assisted alternating current electrodeposition method. The results show that the deposition current density, microstructure, and optical and magnetic properties of the twin composite films exhibit a high degree of symmetry. The distribution of magnetic Co particles in the alumina nanopores can be changed by adjusting the magnitude of the deflected electric field, resulting in a synchronous symmetrical change in the microstructure of the composite films, which enables the fine-tuning of the magneto-optical properties of the twin alumina-Co composite films at the microscopic scale. The current density distribution on the surface of the twin composite films along the direction of the deflected electric field was quantitatively analyzed by theoretical calculations and numerical simulations. The results show that the deposition current density gradually increases from 0.024 A/m2 in region C to 0.056 A/m2 in region A at 6 V deflection voltage. The saturation magnetization intensity gradually increases along the radial direction, which is 118, 130, and 150 kA/m, respectively

A novel magnetic ZnFe2O4 aerogel photocatalyst for visible light reduction of Cr(VI) at high concentrations: Facile synthesis, enhanced activity and photocatalytic mechanism, combined with first-principles calculations

Herein, we prepared a novel magnetic ZnFe 2 O 4 aerogel capable of visible light reduction of Cr(VI) via the sol-gel method. The influences of different heat treatment temperatures on the physical phase, structure, and properties of the catalysts were systematically investigated. Photocatalytic experiments revealed that the 400 °C heat-treated ZnFe 2 O 4 aerogel exhibited the optimal photocatalytic performance. To attenuate the influence of catalyst adsorption on the photocatalytic experiments, the concentration of Cr(VI) solution was as high as 100 mg/L. The reduction rate of Cr(VI) was significantly higher than that of some previously reported ZnFe 2 O 4 photocatalysts after visible light irradiation for 120 min. A plausible photocatalytic reaction mechanism was deduced based on the first-principles DFT calculations and photoelectrochemical experiments. In addition, the 400 °C heat-treated ZnFe 2 O 4 aerogel possessed a high specific surface area of 115.31 m 2 /g and a saturation magnetization intensity of 10.6 emu/g, which allowed for recovery by magnetic separation.

Optimization of magnetization and mechanical properties of Fe-Ni-based alloys by Response Surface Methodology

Fe-Ni-based alloy can have both excellent soft magnetic properties and low Curie temperature. In this paper, 46 groups of Fe-Ni-based alloys are designed by Response Surface Methodology and prepared by arc melting and annealing, and their saturated magnetic polarization intensity (Js) and tensile strength (Rm) are analyzed. The results show that Js and Rm can be fitted with quartic and cubic models to predict the response values. The simultaneous addition of Ni and Cu to the Fe-based alloy has the greatest effect on the Js and Rm. Fe-32Ni-2.7Cr-1.45Cu-1.5Si-2Mn alloy has a Js of 0.51 T, Rm of 302.7 MPa, and Tc of 70 °C, respectively, which can be a potential material for deicing. Importantly, all results show that the response surface methodology can be used to optimize and design multi-component alloy composition while reducing the number of experiments.

Effects of annealing time on nanoscale structural heterogeneity and magnetic properties of Fe<sub>80</sub>Si<sub>9</sub>B<sub>10</sub>Cu<sub>1</sub> amorphous alloy

The evolution of nanoscale structural heterogeneity and its effect on magnetic properties of Fe<sub>80</sub>Si<sub>9</sub>B<sub>10</sub>Cu<sub>1</sub> amorphous alloy during structural relaxation after being annealed for different times are investigated in this work. The nanoscale structural heterogeneity is found to degenerate gradually with relaxation by using the small-angle X-ray scattering and atomic force microscope. Combined with Mössbauer spectroscopy analysis results, the enhanced comprehensive soft magnetic properties of the relaxed alloys can be attributed to the degeneration of nanoscale structural heterogeneity. From the flow unit model, the volume fraction of flow units decreases with relaxation proceeding, and some of the flow units annihilate and transform into the ideal elastic matrix. On the one hand, the relaxed sample with greater packing density has stronger magnetic exchange interaction and higher saturation magnetic flux intensity. On the other hand, the number density of quasi-dislocation dipoles decreases with the annihilation of flow units in the relaxation process, leading the pinning effect of the domain wall to be weakened. Consequently, the magnetic anisotropy decreases after relaxation, which results in the reduction of coercivity. In this work, the structural mechanism of the evolution of magnetic properties in the relaxation process of Fe<sub>80</sub>Si<sub>9</sub>B<sub>10</sub>Cu<sub>1</sub> amorphous alloy is investigated from the perspective of structural heterogeneity, which is helpful in establishing the correlation between the structure and magnetic properties of Fe-based amorphous alloys.

Eco-friendly and acid-resistant magnetic porous carbon derived from ZIF-67 and corn stalk waste for effective removal of imidacloprid and thiamethoxam from water

Neonicotinoids, extensively present in water environment, can adversely affect the ecological safety and human health. Herein, a low-cost magnetic porous carbon ZIF-67/CS@C derived from ZIF-67 and agricultural waste corn stalk (CS) is designed and applied for adsorptive removal of imidacloprid and thiamethoxam from water. The adsorbent is fabricated by carbonizing ZIF-67/CS hybrid pre-prepared through an in-situ decoration of ZIF-67 on the surface of CS, and then acid picking to elute the unstable constituents. In the carbonization, Co2+ ions are reduced to magnetic Co0 nanoparticles, with the result that ZIF-67/CS@C shows a strong magnetic response (saturation magnetization intensity is 12.25 emu‧g−1) and can be easily magnetically separated. Meanwhile, Co nanoparticles are protectively encapsulated in well-developed graphitized wall, which endows ZIF-67/CS@C with good acid resistance (only 0.23% of Co is leached out at pH 1.0). More importantly, reasonable pore size distribution (most pore sizes match or are 3–6 times that of imidacloprid and thiamethoxam) and high external surface area (280 m2‧g−1) are obtained, which makes ZIF-67/CS@C super adsorbent. The adsorption capacities for imidacloprid and thiamethoxam can reach as high as 189 and 133 mg‧g−1, respectively. Moreover, after six consecutive recycling processes, the adsorption efficiencies are still above 95%, which reveals excellent reusability of ZIF-67/CS@C. Mechanism analysis affirms that pore-filling, H-bond, and π-π EDA interaction are mainly responsible for driving imidacloprid and thiamethoxam adsorption. Finally, ZIF-67/CS@C with a great security towards Daphnia carinata survival and wheat growth is eco-friendly. This study can be easily adapted to different biomass wastes and MOFs, thus potentially enabling the preparation of more novel adsorbents.

Effect of Annealing Temperature on the Soft Magnetic Properties of Fe<sub>70.43</sub>Nb<sub>10.77</sub>Si<sub>15.77</sub>Cu<sub>2.34</sub>B<sub>0.69</sub> Amorphous Aanostrips at 20K, 300K

Since Fe-based amorphous alloys are widely used in magnetic separators, sensors and other fields, it is of practical significance to carry out research on amorphous strips used in this field.The effects of annealing temperature on the soft magnetic properties of Fe70.43Nb10.77Si15.77Cu2.34B0.69 amorphous nanostrips with 25 μm and 28 μm thickness prepared by the single roll cold method were investigated at 20 and 300K.Five specimens were annealed at472.12K, 672.12K, 772.12K, 822.12Kand 872.12K, respectively, and their microstructure and magnetic properties were tested viametallographic microscopy, X-ray diffraction, and vibrating specimen magnetometer. At cryogenic temperatureof 20K, specimens annealed at 672,12K exhibited the best magnetic properties, including the coercive forceof8.1265A/m, saturation magnetic induction intensity of1.4351T,and its residual value of 0.2462T. The comparative analysis of experimental results obtained strongly indicates that the soft magnetic properties of the amorphous alloy are significantly improved by the particular annealing treatment.

Adsorption Mechanism of Cadmium by Superparamagnetic Nano-Fe3 O4@SiO2 Functionalized Materials

The treatment of cadmium-containing wastewater is of great significance for the emission control of the heavy metal cadmium. Here, a superparamagnetic nano-Fe3O4@SiO2 functionalized material (MFS) was prepared via a co-precipitation method, and the adsorption thermodynamic and kinetic characteristics of Cd2+ were studied by isothermal adsorption tests and kinetic experiments. The adsorption process and mechanism of MFS with respect to Cd2+ were also studied using BET, XRD, and SEM. The Langmuir equation well described the isothermal adsorption characteristics of MFS, and the maximum adsorption capacity was 69.49 mg·g-1. The standard free energy (ΔG), enthalpy (ΔH), and entropy changes (ΔS) showed that the adsorption reaction was a spontaneous, endothermic, and entropic process. The optimal initial pH of the adsorption reaction was 7. The four interfering ions (Mg2+, SO42-, Ca2+, and NO3-) in the solution had a certain inhibitory effect on the adsorption reaction. The pseudo-second-order kinetic model showed that the adsorption process of Cd2+ was divided into two stages, namely a rapid external diffusion stage and a slow internal diffusion stage. The removal rate of Cd2+ was still>73% after using the MFS three times. The BET, XRD, FTIR, and VSM analyses showed that SiO2 was successfully modified on the Fe3O4 surface. MFS is mainly spherical in structure with an average particle size of 38.7 nm and has a saturated magnetic intensity of 85.38 emu·g-1. The XRD, EDS, and XPS analyses revealed that Cd2+ was successfully adsorbed by the material, and the main mechanism was the coordination reaction between Cd2+ and -OH on the surface of the material.

The irradiation variation of amorphous alloy FeSiB using for fusion devices induced by 2 MeV He ions

Because of its unique long range disordered structure and numerous free volume, amorphous alloy is considered to be able to accommodate the damage caused by ion bombardment and has good irradiation resistance. 2 MeV He+ ions were selected to irradiate amorphous alloy Fe80Si7B13, and it was found that the arrangement of atoms in the amorphous alloy became uneven. In the bubble layer located near the He ion range which was about 3.5 μm from the surface, the local atoms had a tendency of ordered arrangement. Under the irradiation, no obvious damage could be observed on the surface of the amorphous alloy, while the surface roughness increased, which reduced the surface relative reflectivity of the amorphous alloy. After the irradiation, the Fe-based amorphous alloy maintained the soft magnetic performance. The variation of atomic arrangement in the amorphous alloy enhanced its saturation magnetic induction intensity.

Citric acid coated ultrasmall superparamagnetic iron oxide nanoparticles conjugated with lactoferrin for targeted negative MR imaging of glioma.

The proposed study was to develop the preparation of ultrasmall superparamagnetic iron oxide nanoparticles (USPIONs) modified with citric acid, with surface conjugated with lactoferrin (Lf), which used as a potential targeted contrast agent for magnetic resonance imaging (MRI) of brain glioma. USPIONs were prepared by the thermal decomposition method. The hydrophobic USPIONs were coated with citric acid by the ligand exchange method. Then, Lf was conjugated into the surface of USPIONs. The obtained Lf-USPIONs were analyzed by fourier transform infrared (FTIR) spectroscopy and polyacrylamide gel electrophoresis. The size, size distribution, shape and superparamagnetic property of Lf-USPIONs were investigated with TEM and vibrating sample magnetometer (VSM). Both FTIR and electrophoresis analysis demonstrated the successful conjugation of Lf to the surface of USPIONs. The average size of Lf-USPIONs was about 8.4 ± 0.5 nm, which was determined using the statistics of measured over 100 nanoparticles in the TEM image, with a negative charge of -7.3 ± 0.2 mV. TEM imaging revealed that Lf-USPIONs were good in dispersion and polygonal in morphology. VSM results indicated that Lf-USPIONs were superparamagnetic and the saturated magnetic intensity was about 69.8 emu/g. The Lf-USPIONs also showed good biocompatibility in hemolysis, cytotoxicity, cell migration and blood biochemistry studies. MR imaging results in vitro and in vivo indicated that Lf-USPIONs exhibited good negative contrast enhancement. Taken together, Lf-USPIONs hold great potential for brain gliomas MR imaging as a nanosized targeted contrast agent.

Petromagnetic Properties of Fallow Soils as an Indicator of the Organic-Matter Content

The magnetic properties of chernozem soils, dark and light gray forest soils, and sod-podzolic soils present in the Republic of Tatarstan have been researched and described using the petromagnetism method, coercive spectrometry, and X-ray phase analysis with the purpose of improving the soil monitoring system in relation to fallow and virgin soils. In the course of soil genesis, iron compounds undergo transformations and the magnetic parameters of the soil profile change in comparison with the parent rocks. It can be said that the magnetic profile reflects the pedogenesis processes. A statistically significant relationship between the humus content on the one hand and the susceptibility and intensity of remanent saturation magnetization (Jrs) on the other hand has been identified. A technique making it possible to separate the contributions of lithogenic and pedogenic magnetic minerals to the saturation remanence (Jrs) intensity has been developed on the basis of coercive spectrometry. In the studied soils, the pedogenic component primarily consists of the organogenic extracellular constituent of the magnetite–maghemite association, which is the best candidate to proxy in assessments of the humus concentration in soils at various depths with magnetic methods.

Multifunctional Fe3O4@SiO2-CDs magnetic fluorescent nanoparticles as effective carrier of gambogic acid for inhibiting VX2 tumor cells

This paper reports a dual-functional platform that can be used for synergistic therapy, including drug release and magnetic targeting. The platform is realized through an amide reaction between high-fluorescence carbon quantum dots (CD) prepared by microwave method and amino-functional Fe3O4@SiO2 with high saturation magnetic strength and a core-shell structure to obtain multifunctional magnetic fluorescent nanocomposite particles Fe3O4@SiO2-CDs. The structure, drug release behavior, cytotoxicity, fluorescence and distribution in vivo of Fe3O4@SiO2-CDs nanoparticles were studied. The results show that the Fe3O4@SiO2-CDs with a dynamic diameter of about 155.0 nm and a magnetic saturation intensity of 31.2 emu/g has a higher loading of gambogic acid (GA), and is more conducive to drug release in an environment of pH = 5.7. In addition, Fe3O4@SiO2-CDs has low cytotoxicity and can enter VX2 cells. However, GA-loaded Fe3O4@SiO2-CDs has an inhibitory effect on VX2 cells, and the cell survival rate is less than 20% at a concentration of 100 μg/mL. Magnetic targeting experiments show that bifunctional magnetic nanoparticles have an outstanding magnetic targeting effect on tumors.

The influence of successive irradiation of He and H ions on the structure, morphology and property of metallic glass Fe80B13Si7

500 keV He ions and 250 keV H ions was used to irradiate the metallic glass Fe80B13Si7. When the fluence increased to 2 × 1017 He ions/cm2 + 1 × 1018H ions/cm2 or 1 × 1018 He ions/cm2 + 5 × 1017H ions/cm2, no crystallization or obvious surface damage appeared in the metallic glass. Compared with the case of He ions or H ions irradiation, the successive irradiation of both ions roughened the surface of the Fe-based metallic glass. Under the successive irradiation, the He bubble layer thickened due to the diffusion of bubbles, and the size of bubbles decreased while the number density increased. The metallic glass Fe80B13Si7 still maintained good soft magnetic property under the successive irradiation, while its saturation magnetic induction intensity and coercive force changed slightly.

The structure of copper ferrite prepared by five methods and its catalytic activity on lignin oxidative degradation

Effects of copper ferrites with different prepared methods on the catalytic degradation of lignin with hydrogen peroxide as oxidant is studied. The microstructure, spectral properties and magnetic properties of copper ferrites prepared with five methods were characterized. The results showed that the microcosmic appearance of the catalysts prepared by the five methods was nanoparticles or irregular blocks. All the samples have strong magnetic properties. However the magnetic saturation intensity, residual magnetic intensity and coercivity of copper ferrite prepared by different methods are distinct. The degradation rate and the content of benzene-ring substances were the highest when lignin decomposed under the catalyst of copper ferrite prepared by ethylene glycol assisted sol-gel process, while the content of open-ring substances was the highest when lignin decomposed under the catalyst of copper ferrite made by co-precipitation. Compared with Fenton catalyst, The copper ferrite catalyst easily be separated and good repetitive catalytic performance when used in the lignin degradation. In addition, the crystal structure of copper ferrite play an important role on the catalytic degradation properties of lignin.

Adsorption characteristics and mechanism of norfloxacin in water by γ-Fe2O3@BC

Using waste pomelo peel as raw material, pomelo peel-based biochar (BC) was prepared by pyrolysis at 400 °C, and the pomelo peel-based biochar was prepared by loading γ-Fe2O3 onto the surface of the pomelo peel-based biochar by unlimited oxygen chemical precipitation. The results showed that the pomelo peel biochar loaded with γ-Fe2O3 had higher specific surface area and larger pore volume. The load of γ-Fe2O3 gives γ-Fe2O3@BC excellent magnetic separation ability, and its magnetic saturation intensity is as high as 30.60 emu/g. BC and γ-Fe2O3@BC were applied to remove norfloxacin (NOR) from a water body. It was found that the adsorption of NOR by both of them followed the pseudo-second-order kinetic model. The adsorption isotherm mainly conforms to the Sips model, and the adsorption process of NOR is a spontaneous endothermic reaction. The pH and ionic strength have a great influence on the adsorption of NOR by BC and γ-Fe2O3@BC, and they play a role mainly by influencing the morphology of NOR in water. The adsorption mechanism showed that cation exchange and hydrogen bonding were the main forces for BC to adsorb NOR. Moreover, the γ-Fe2O3 particles enhanced the hydrophobicity of the pomelo peel-based biochar, making the hydrophobicity become the main force for the adsorption of NOR by the γ-Fe2O3@BC. The adsorption-desorption experiment showed that after four cycles of recycling, the adsorption capacity of γ-Fe2O3@BC for NOR was still up to 61.43% of the initial adsorption capacity, and it had a good recycling property.

Synthesis of a novel magnetic–luminescent bifunctional imaging materials by introducing WO3–x interlayer

A novel Fe3O4@WO3–x@YF3:Ce3+, Tb3+ imaging material was prepared by two-step method. Compared with the YF3:Ce3+, Tb3+, the luminescence intensity of Fe3O4@WO3–x@YF3:Ce3+,Tb3+ is obviously boosted. It showed that the protect effect and LSPR of WO3–x shielding layer play a role in enhancing the luminescence properties of the YF3: Ce3+, Tb3+. MTT assays showed that biomaterials have no poisonousness or harmful after-effects in cells. The magnetic saturation intensity is not obviously weakened by inserting WO3–x layer. The method can boost the luminescent property of the magnetic–luminescent material and stimulate its applications in cell imaging, targeting delivery, and thermotherapy. In this study, Fe3O4@WO3–x@YF3:Ce3+,Tb3+ magnetic-luminescent bi-functional nanocomposites with best luminescent performance were synthesized by a simple direct precipitation method. Furthermore, the enhancement mechanism has been found as LSPR of WO3−x. The nanocomposites are potential application in tumor imaging and tumor precise surgery.

Study of preparation and characteristics of transition metal-doped ZnO: Li thin films deposited by magnetron co-sputtering*

The metals (Co, Cu) -doped ZnO: Li films are prepared on Si (100) by using the magnetron co-sputtering method. Using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and vibrating sample magnetometer (VSM), the structure, surface morphology and magnetic properties of the films are measured. All the samples show room temperature ferromagnetism. The saturation magnetization intensity increases from 3.67 emu/cm3 to 5.78 emu/cm3, and the coercive force increases from 70Oe to 82Oe after annealing for Co-doped ZnO: Li films. The magnetism does not significantly change before and after annealing for Cu-doped ZnO: Li films.

Iron Nanoparticles for Low-Power Local Magnetic Hyperthermia in Combination with Immune Checkpoint Blockade for Systemic Antitumor Therapy.

Magnetic hyperthermia (MHT) utilizing heat generated by magnetic nanoparticles under alternating magnetic field (AMF) is an effective local tumor ablation method but can hardly treat metastatic tumors. In this work, we discover that pure iron nanoparticles (FeNPs) with high magnetic saturation intensity after being modified by biocompatible polymers are stable in aqueous solution and could be employed as a supereffective MHT agent to generate sufficient heating under a low-power AFM. Effective MHT ablation of tumors is then achieved, using either locally injected FeNPs or intravenously injected FeNPs with the help of locally applied tumor-focused constant magnetic field to enhance the tumor accumulation of those nanoparticles. We further demonstrate that the combination of FeNP-based MHT with local injection of nanoadjuvant and systemic injection of anticytotoxic T-lymphocyte antigen-4 (anti-CTLA4) checkpoint blockade would result in systemic therapeutic responses to inhibit tumor metastasis. A robust immune memory effect to prevent tumor recurrence is also observed after the combined MHT-immunotherapy. This work not only highlights that FeNPs with appropriate surface modification could act as a supereffective MHT agent but also presents the great promises of combining MHT with immunotherapy to achieve long-lasting systemic therapeutic outcome after local treatment.

Fabrication of magnetic lignosulfonate using ultrasonic-assisted in situ synthesis for efficient removal of Cr(Ⅵ) and Rhodamine B from wastewater.

A novel and eco-friendly one-step approach has been developed to fabricate magnetic lignosulfonate (MLS) with high performance in wastewater treatment. The obtained MLS was characterized by FTIR, XRD, SEM, TEM, VSM. The results showed that MLS had a good magnetic behavior in an applied magnetic field and its saturation magnetization intensity was up to 43.98 emu/g. Moreover, MLS exhibited excellent adsorption properties for Cr(Ⅵ) (57.14 mg/g) and Rhodamine B (22.47 mg/g). Simultaneously, the adsorption kinetics and adsorption isotherm experiments indicated that the data was agreed well with the pseudo-second-order and Langmuir model, respectively. After five regeneration cycles, the desorption efficiencies of Cr(Ⅵ) and Rhodamine B could reach more than 70% and 85%, respectively. Hence, the magnetic lignosulfonate is a promising material as a highly adsorptive and recyclable adsorbent for removing metal ions and cationic pollutants in wastewater.