Carbon-coated magnetic particles increase tissue temperatures after laser irradiation

Purpose:This work focused on the investigation the hyperthermia performance of the carboncoated magnetic particles(CCMPs)in laser-induced hyperthermia.Materials and methods:We prepared CCMPs using the organic carbonization method,and then characterized them with transmission electron microscopy(TEM),ultraviolet-visible(UV-Vis)spectrophotometry,vibrating sample magnetometer(VSM)and X-ray di®raction(XRD).In order to evaluate their performance in hyperthermia,the CCMPs were tested in laser-induced thermal therapy(LITT)experiments,in which we employed a fully distributedfiber Bragg grating(FBG)sensor to profile the tissue's dynamic temperature change under laser irradiation in real time.Results:The sizes of prepared CCMPs were about several micrometers,and the LITT results show that the tissue injected with the CCMPs absorbed more laser energy,and its temperature increased faster than the contrast tissue without CCMPs.Conclusions:The CCMPs may be of great help in hyperthermia applications.

Preparation of Fe_3O_4/PS Magnetic Particles by Dispersion Polymerization

Fe_3O_4/PS magnetic particles with core/shell structure has been prepared in the presence of Fe3O4 magnetic fluid in ethanol/water mixture.Magnetic particles with diameter size range from 5. 54 t0 187. 32 μm were obtained by different reaction conditions.Some parameters such as ethanol, PEG and monomer which affect particle size diameter and size distribution are discussed briefly in this paper.

PREPARATION OF Fe_3O_4/PSt MAGNETIC PARTICLES IN THE PRESENCE OF MAGNETIC FLUID IN ETHANOL/WATER MIXTURE

Fe_3O_4/Polystyrene(PSt) magnetic particles with core/shell structure have been prepared in thepresence of Fe_3O_4 magnetic fluid in ethanol/water medium by dispersion polymeriation of styrene. A Fe_3O_4particle formation mechanism was proposed. According to this mechanism, the size of particle nuclei isdetermined by the extent of aggregation of Fe_3O_4 /oligomer. Magnetic particles with diameter ranging from 5to 200 μm were prepared under different reaction conditions. Some polymerization parameters such as theconcentration of monomer, stabilizer, initiator, and ethanol which affect particle size and size distribution arediscussed and their effect on particle formation are explained by the proposed mechanism.

Interaction forces between soft magnetic particles in uniform and non-uniform magnetic fields

The influence of the magnetization of a soft magnetic sphere on the surrounding magnetic field is measured and characterized.The interaction force between two soft magnetic particles is directly measured using an ultra precision load sensor in uniform and non-uniform magnetic fields. The interaction force largely follows an inverse fourth power law as a function of separation distance between particle centers. At small distances,the effect of magnetization of one particle on the magnetization of its adjacent particle causes the attractive（repulsive） force to be larger（smaller） than that predicted by the inverse fourth power law.The theoretical prediction based on a modified dipole model,that takes into account the coupling effect of the magnetization among soft magnetic particles,gives excellent agreement with the measured force in a uniform magnetic field.The interaction force under a non-uniform applied magnetic field can be reasonably predicted using the dipole-dipole interaction model when the local magnetic field is used to determine the magnetization.

Synthesis and surface modification of magnetic particles for application in biotechnology and biomedicine

Magnetic particles have numerous applications in biotechnology and biomedicine. In this paper we reviewed the synthesis, surface modification and some applications of magnetic particles with focus on their synthesis and surface modification. Various methods have been developed for the production of magnetic particles （magnetic nanoparticles and magnetic composite particles）. For future application magnetic particles must be modified to obtain stability and surface functional groups. Finally, the application of magnetic particles in magnetic separation, drug delivery, hyperthermia, and magnetic resonance imaging are discussed.

Coupling magnetic particles with flocculants to enhance demulsification and separation of waste cutting emulsion for engineering applications

Magnetic particles were coupled with a flocculant to enhance the demulsification and separation of waste cutting emulsions.The optimal magnetic particle size and critical magnetic field conditions were investigated to achieve large-scale engineering application of magnetic demulsification separation for waste cutting emulsion treatment.The micro-scale magnetic particles were found to show comparable effects to nano-scale magnetic particles on enhancing the demulsification and separation of cutting emulsions,which are beneficial for broadening the selectivity of low-cost magnetic particles.The critical magnetic separation region was determined to be an area 40 mm from the magnetic field source.Compared to the flocculant demulsification,the magnetic demulsification separation exhibited a significant advantage in accelerating flocs-water separation by decreasing the separation time of flocs from 180-240 min to less than 15 min,compressing the flocs by reducing the floc volume ratio from 60%-90%to lower than 20%,and showing excellent adaptability to the variable properties of waste cutting emulsions.Coupled with the design of the magnetic disk separator,continuous demulsification separation of the waste cutting emulsion was achieved at 1.0 t/hr for at least 10 hr to obtain clear effluent with 81%chemical oxygen demand removal and 89%turbidity reduction.This study demonstrates the feasibility of applying magnetic demulsification separation to large-scale continuous treatment of waste emulsion.Moreover,it addresses the flocs-water separation problems that occur in practical flocculant demulsification engineering applications.

Old commercialized magnetic particles new trick: Intrinsic internal standard

Magnetic particles (MPs) are the most widely used commercialized engineering particles, which gained great success in various biological applications. Inspired by their intrinsic Fe isotope composition, we discovered a commercialized MPs-internal standard's novel function to realize the accurate quantification of biomolecules. The bioassay of carcinoembryonic antigen (CEA) was chosen as a modal system. The Fe isotope in MPs and Au isotope in report probes were simultaneously and sensitively detected by the elemental mass spectrometry. ^(197)Au/^(57)Fe isotopic ratios and CEA concentrations showed good linearity in the range of 0.6-300 ng/mL, with a detection limit of 0.09 ng/mL (3σ). The accuracy and precision of the proposed MPs-based immunoassay were greatly improved, by eliminating potential MPs loss during magnetic separation and absolute intensity fluctuations. Considering the exceptional availability and universality of commercialized MPs, the proposed method might open a new avenue for MPs' biological applications.

Fabrication of SrFe_(12-x)Ni_xO_(19) nanoparticles and investigation on their structural, magnetic and dielectric properties

Sr Fe12-xNixO19 nanoparticles(x = 0–1) were synthesized by a combustion sol–gel method. Their structure, dielectric and magnetic properties were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM), an LCR metry, and vibrating sample magnetometry(VSM).The results reveal that all samples of Ni doped compounds(Sr Fe12-xNixO19) with x < 0.2 are single phase. It appears that the Fe3+ ions are substituted by Ni2+ ions on the crystallographic sites of the Sr Fe12O19 structure; however, for x ≥ 0.2, the secondary Ni phase ferrite(Ni Fe2O3) appears, which reduces the saturation magnetization and coercivity. In addition, Ni doping reduces the dielectric constant, dielectric loss, and alternating current(ac) electrical conductivity of the samples. The variation in ac conductivity(σac) with frequency shows that the electrical conductivity in these ferrites is mainly attributed to the electron hopping mechanism.Therefore; all the single-phase Ni doped samples are suitable for use in magnetic recording media and microwave devices.

Modeling and measurement of curing properties of photocurable polymer containing magnetic particles and microcapsules

In microstereolithography,three-dimensional microstructures are created by scanning an ultraviolet laser on a photocurable resin and stacking several such layers to form the desired structure.By mixing different types of particles in the resin,the formed microstructures exhibit various physical properties.For example,the magnetism and density of the microstructure can be controlled by adding magnetic particles and microcapsules to the resin.This method has been used to fabricate magnetic micromachines.Although such functional resins are useful,the incorporated magnetic particles and microcapsules can affect the fabrication resolution,making it difficult to fabricate microstructures with high precision.Thus,it is necessary to understand the effects of such microparticles and microcapsules on the fabrication process.In this study,we propose a simple model of curing resins containing magnetic particles and microcapsules to explain the effects of the magnetic particles and microcapsules.The proposed model can explain the observed curing characteristics of a resin that contains particles for all concentrations as well as for different types of magnetic particles and microcapsules.Finally,using the proposed model,we discuss how to improve the characteristics of resins containing microparticles to realize the high-resolution fabrication of three-dimensional microstructures with desirable material properties.

High-Sensitivity Detection of Fruit Tree Viruses UsingBacterial Magnetic Particles

Prunus necrotic ring spot virus （PNRSV） and grapevine fanleaf virus （GFLV） were detected by fluoroimmunoassay using bacterial magnetic particles （BMPs）, and a double antibody sandwich enzyme linked immunosorbent assay （DAS-ELISA）. For the fluoroimmunoassay, fluorescein isothiocyanate labeled anti-PNRSV antibody or anti-GFLV antibody was conjugated onto BMPs of Magnetospirillum gryphiswaldense MSR-1. With this method, a very low minimum antigen concentration （1×10^6 dilution of the original sample concentration） could be detected. Using DAS-ELISA, the minimum antigen detection concentration was the original sample concentration. Thus, comparing these two methods, a BMP-based method could increase the sensitivity up to six orders of magnitude （10^6） higher than an ELISA-based method of detection PNRSV and GFLV.

Magnetic Particle Imaging for Magnetic Hyperthermia Treatment: Visualization and Quantification of the Intratumoral Distribution and Temporal Change of Magnetic Nanoparticles in Vivo

Purpose: Magnetic hyperthermia treatment (MHT) is a strategy for cancer therapy using the tem-perature rise of magnetic nanoparticles (MNPs) under an alternating magnetic field (AMF). Re-cently, a new imaging method called magnetic particle imaging (MPI) has been introduced. MPI allows imaging of the spatial distribution of MNPs. The purpose of this study was to investigate the feasibility of visualizing and quantifying the intratumoral distribution and temporal change of MNPs and predicting the therapeutic effect of MHT using MPI. Materials and Methods: Colon-26 cells (1 × 106 cells) were implanted into the backs of eight-week-old male BALB/c mice. When the tumor volume reached approximately 100 mm3, mice were divided into untreated (n = 10) and treated groups (n = 27). The tumors in the treated group were directly injected with MNPs (Resovist?) with iron concentrations of 500 mM (A, n = 9), 400 mM (B, n = 8), and 250 mM (C, n = 10), respectively, and MHT was performed using an AMF with a frequency of 600 kHz and a peak amplitude of 3.5 kA/m. The mice in the treated group were scanned using our MPI scanner immediately before, immediately after, 7 days, and 14 days after MHT. We drew a region of interest (ROI) on the tumor in the MPI image and calculated the average, maximum, and total MPI values and the number of pixels by taking the threshold value for extracting the contour as 40% of the maximum MPI value (pixel value) within the ROI. These parameters in the untreated group were taken as zero. We also measured the relative tumor volume growth (RTVG) defined by (V-V0)/V0, where V0 and V are the tumor volumes immediately before and after MHT, respectively. Results: The average, maximum, and total MPI values decreased up to 7 days after MHT and remained almost constant thereafter in all groups, whereas the number of pixels tended to increase with time. The RTVG values in Groups A and B were significantly lower than those in the control group 3 days or more and 5 days or more after MHT, respectively. The above four parameters were significantly inversely correlated with the RTVG values 5, 7, and 14 days after MHT. Conclusion: MPI can visualize and quantify the intratumoral distribution and temporal change of MNPs before and after MHT. Our results suggest that MPI will be useful for predicting the therapeutic effect of MHT and for the treatment planning of MHT.

Two-Phase Flow of Blood with Magnetic Dusty Particles in Cylindrical Region: A Caputo Fabrizio Fractional Model

The present study is focused on the unsteady two-phase flow of blood in a cylindrical region.Blood is taken as a counter-example of Brinkman type fluid containing magnetic(dust)particles.The oscillating pressure gradient has been considered because for blood flow it is necessary to investigate in the form of a diastolic and systolic pressure.The transverse magnetic field has been applied externally to the cylindrical tube to study its impact on both fluids as well as particles.The system of derived governing equations based on Navier Stoke’s,Maxwell and heat equations has been generalized using the well-known Caputo–Fabrizio(C–F)fractional derivative.The considered fractional model has been solved analytically using the joint Laplace and Hankel(L&H)transformations.The effect of various physical parameters such as fractional parameter,Gr,M and
γ on blood and magnetic particles has been shown graphically using the Mathcad software.The fluid behaviour is thinner in fractional order as compared to the classical one.

Study on Optimizing High-Gradient Magnetic Separation—Part 1: Improvement of Magnetic Particle Retention Based on CFD Simulations

The introduction of functionalized magnetizable particles for the purification of enzymes or for the multi-use of pre-immobilized biocatalysts offers a great potential for time and cost savings in biotechnological process design. The selective separation of the magnetizable particles is performed for example by a high-gradient magnetic separator. In this study FEM and CFD simulations of the magnetic field and the fluid flow field within a filter chamber of a magnetic separator were carried out, to find an optimal separator design. The motion of virtual magnetizable particles was calculated with a one-way coupled Lagrangian approach in order to test many geometric and parametric variations in reduced time. It was found that a flow homogenisator smoothed the fluid flow, so that the linear velocity became nearly equal over the cross section in the direction of flow. Furthermore the retention of magnetizable particles increases with a high total edge length within the filter matrix.

Study on Optimizing High-Gradient Magnetic Separation—Part 2: Experimental Evaluation of the Performance of a New Designed Magnetic Filter

The introduction of functionalized magnetizable particles and high-gradient magnetic separation represents a time and money saving alternative to conventional purification and separation unit operations in the biotechnical sector. This technique has some advantages especially for the recycling of immobilized enzymes. A new magnetic filter with sight glasses was constructed and produced to study the performance of high-gradient magnetic separation at varied parameters. By optical analysis the buildup of a clogging was identified as the major parameter which affected the separation performance. For the cleaning procedure, a two-phase flow of water with highly dispersed air bubbles was tested which led to a nearly complete cleaning of the filter chamber.

Aggregation of ferromagnetic and paramagnetic atoms at edges of graphenes and graphite

In this work we report that when ferromagnetic metals （Fe, Co and Ni） are thermMly evaporated onto n-layer graphenes and graphite, a metal nanowire and adjacent nanogaps can be found along the edges regardless of its zigzag or armchair structure. Similar features can also be observed for paramagnetic metals, such as Mn, Al and Pd. Meanwhile, metal nanowires and adjacent nanogaps cannot be found for diamagnetic metals （Au and Ag）. An external magnetic field during the evaporation of metals can make these unique features disappear for ferromagnetic and paramagnetic metal; and the morphologies of diamagnetic metal do not change after the application of an external magnetic field. We discuss the possible reasons for these novel and interesting results, which include possible one-dimensional ferromagnets along the edge and edge-related binding energy.

Electromagnetic Shells of Atoms and the Periodic System of Elements

Experimental and theoretical researches performed by the author (period: 1969-present) showed that the magnetic spinor particles (magnetic charges) are real structural components of atoms and substance and are immediate sources of all mag-netic fields and magnetic manifestations in Nature. Magnetic charges, which constitute together with electrical charges the atomic shells, got of the Author’s title: magnetons and antimagnetons (respectively, with magnetic charges g− and g+, under fundamental condition: g = e). Besides, together with electrons and magnetic charges in the structures of atomic shells, in the same quantities as the electrons, exist real electric antispinors, i.e. the true antielectrons. In the structures of the atomic shells on each electron fitted still three a real spinor particles: two magnetic (magneton and antimagneton) and one electric, i.e. true antielectron with a charge of e+. The spinor particles in atomic shells exist in the form of the two spinor associations: the electromagnetic dibispinors or S-Gravitons and magnetic bispinors (spinorial magnetic dipoles). Magnetic bispinors, which inhabited on the 3d and 4f-shells are the sources of the atomic magnetic fields and are responsible at all magnetic manifestations of the so-called magnetic atoms (iron, nickel, cobalt and others). In composition of S-Graviton is two related bispinor (electric and magnetic). S-Gravitons make up bulk of the charged density of atomic shells and are direct sources of the atomic gravitational field.If to replace all electrons on known of the atomic levels and sub-levels on S-Gravitons, can get an idea about the real electromagnetic device atomic shells most of the elements making up the Periodic Table. In article shows features the structural organization real (electromagnetic) shells of atoms that make up the periodic system of elements, as well as is considered the possibility of adaptation of the well-known quantum numbers, the Pauli’s principle and Hund’s rule, in relation to the atomic electromagnetic device. The main reasons for the fact that the real magnetic charges, as well as the true antielectrons, were “buried alive” in the modern theories are as physics confinement them in atoms and substance, which is cardinally different from the confinement, for example, electrons, so and vicious electromagnetic concept of Maxwell. In the framework of this concept really existing in atoms and substance the magnetic charges, have been mistakenly substituted on acts of the mechanical displacement of electrical charges.

Usefulness of Magnetic Particle Imaging for Monitoring the Effect of Magnetic Targeting

Purpose: Magnetic targeting refers to the attachment of therapeutic agents to magnetizable particles such as magnetic nanoparticles (MNPs) and then applying magnetic fields to concentrate them to the targeted region such as solid tumors. The purpose of this study was to investigate the usefulness of magnetic particle imaging (MPI) for monitoring the effect of magnetic targeting using tumor-bearing mice. Materials and Methods: Colon-26 cells (1 × 106 cells) were implanted into the backs of eight-week-old male BALB/c mice. When the tumor volume reached approximately 100 mm3, the mice were divided into treated (n = 8) and untreated groups (n = 8). The tumors in the treated group were directly injected with MNPs (Resovist?, 250 mM) and a neodymium magnet was attached to the tumor surface, whereas the magnet was not attached to the tumor in the untreated group. The mice were imaged using our MPI scanner and the average and maximum MPI values were obtained by drawing a region of interest (ROI) on the tumor, with the threshold value for extracting the contour of the tumor being taken as 40% of the maximum MPI value in the ROI. The relative tumor volume growth (RTVG) was calculated from (V ? V0)/V0, where V0 and V represented the tumor volume immediately before and after the injection of MNPs, respectively. Results: The average and maximum MPI values in the treated group were significantly higher than those in the untreated group 3 days after the injection of MNPs, suggesting the effectiveness of magnetic targeting. There were no significant differences in RTVG between the two groups. Conclusion: Our preliminary results suggest that MPI is useful for monitoring the effect of magnetic targeting.

Surface Modification of a-Fe Metal Particles by Chemical Surface Coating

The structure of a-Fe metal magnetic recording particles coated with silane coupling agents have been studied by TEM, FT-IR, EXAFS, Mossbauer. The results show that a close, uniform, firm and ultra thin layer, which is beneficial to the magnetic and chemical stability, has been formed by the cross-linked chemical bond Si-O-Si. And the organic molecule has chemically bonded to the particle surface, which has greatly affected the surface Fe atom electronic structure. Furthermore, the covalent bond between metal particle surface and organic molecule has obvious effect on the near edge structure of the surface Fe atoms.

Recent developments of the reconstruction in magnetic particle imaging

Magnetic particle imaging(MPI)is an emerging molecular imaging technique with high sensitivity and temporal-spatial resolution.Image reconstruction is an important research topic in MPI,which converts an induced voltage signal into the image of superparamagnetic iron oxide particles concentration distribution.MPI reconstruction primarily involves system matrix-and x-space-based methods.In this review,we provide a detailed overview of the research status and future research trends of these two methods.In addition,we review the application of deep learning methods in MPI reconstruction and the current open sources of MPI.Finally,research opinions on MPI reconstruction are presented.We hope this review promotes the use of MPI in clinical applications.

Observation of Magnetic Dipole Forbidden Transitions in LHD and Its Application to Burning Plasma Diagnostics

Magnetic dipole forbidden （M1） transition was studied in large helical device （LHD） and F-, Si- and Ti-like M1 transitions are successfully observed for highly ionized Ar, Kr, Mo and Xe ions. The wavelengths measured in visible range for the heavy elements, which are carefully determined with extremely small uncertainties of 0.02 - 0.05 A as a standard wavelength of usual electric dipole （El） plasma emissions, are compared with theoretical predictions. The result shows a good agreement with recent Hatree-Fock calculation including semi-empirical adjustment. The M1 intensity for the F-like ions is examined by analyzing the intensity ratio of M1 to El. Density dependence of the ratio is experimentally verified by comparing with collisional- radiative model calculation on level population. The M1/E1 line ratio for the F-like ions is applied to the α （He^2＋） particle diagnostics in ITER, in which a steady-state operation of burning plasmas based on D-T fusion reaction is expected with α particle heating. Unfortunately, the present estimation suggests a negative result for the α particle measurement because the ratio is largely enhanced by the collisional excitation with bulk ions due to high ion temperature of ITER of 10 keV as assumed and the resultant effect of the collisional excitation with α particles becomes less. Meanwhile, the M1 transition, in particular, Ti-like WLIII （W^52＋） transition （3627 A） emitted in visible range, is very useful for diagnostics of the impurity behavior and the core plasma parameters in ITER.