WorldWideScience

Sample records for magnetic particles displaying

  1. Development of a novel method for screening of estrogenic compounds using nano-sized bacterial magnetic particles displaying estrogen receptor

    Energy Technology Data Exchange (ETDEWEB)

    Yoshino, Tomoko [Department of Biotechnology, Tokyo University of Agriculture and Technology, 2 24 16 Naka-cho, Koganei, Tokyo 184-8588 (Japan); Kato, Fukuichi [Department of Biotechnology, Tokyo University of Agriculture and Technology, 2 24 16 Naka-cho, Koganei, Tokyo 184-8588 (Japan); Takeyama, Haruko [Department of Biotechnology, Tokyo University of Agriculture and Technology, 2 24 16 Naka-cho, Koganei, Tokyo 184-8588 (Japan); Nakai, Makoto [Chemicals Assessment Center, Chemicals Evaluation and Research Institute, 1600 Shimo-Takano, Sugito-machi, Kitakatsushika-gun, Saitama 345-0043 (Japan); Yakabe, Yoshikuni [Chemicals Assessment Center, Chemicals Evaluation and Research Institute, 1600 Shimo-Takano, Sugito-machi, Kitakatsushika-gun, Saitama 345-0043 (Japan); Matsunaga, Tadashi [Department of Biotechnology, Tokyo University of Agriculture and Technology, 2 24 16 Naka-cho, Koganei, Tokyo 184-8588 (Japan)]. E-mail: tmatsuna@cc.tuat.ac.jp

    2005-03-14

    In this study, nano-sized bacterial magnetic particles (BMPs) displaying human estrogen receptor ligand binding domain (ERLBD) on the surface was successfully produced by the magnetic bacterium, Magnetospirillum magneticum AMB-1. Furthermore, a non-isotopic binding assay for estrogenic compounds using the BMPs displaying ERLBD was developed. A BMP membrane-specific protein, Mms16, was used as an anchor molecule to localize ERLBD on the surface of BMPs. ERLBD-BMP complexes were simply extracted by magnetic separation from ruptured AMB-1 transformants and used for the assay based on the competitive binding of alkaline phosphatase conjugated 17{beta}-estradiol (ALP-E2) as a tracer. Dissociation constant of the receptor was 2.3 nM. Inhibition curves were evaluated by the decrease in luminescence intensity resulting from the enzymatic reaction of alkaline phosphatase. The overall simplicity of this receptor binding assay results in a method that can be easily adapted to a high throughput format. Moreover, this method can be integrated into a fully-automated ligand screening system using magnetic separation.

  2. Magnetic particle characterization-magnetophoretic mobility and particle size.

    Science.gov (United States)

    Zhou, Chen; Boland, Eugene D; Todd, Paul W; Hanley, Thomas R

    2016-06-01

    Quantitative characterization of magnetic particles is useful for analysis and separation of labeled cells and magnetic particles. A particle velocimeter is used to directly measure the magnetophoretic mobility, size, and other parameters of magnetic particle suspensions. The instrument provides quantitative video analysis of particles and their motion. The trajectories of magnetic particles in an isodynamic magnetic field are recorded using a high-definition camera/microscope system for image collection. Image analysis software then converts the image data to the parameters of interest. The distribution of magnetophoretic mobility is determined by combining fast image analysis with velocimetry measurements. Particle size distributions have been characterized to provide a better understanding of sample quality. The results have been used in the development and operation of analyzer protocols for counting particle concentrations accurately and measuring magnetic susceptibility and size for simultaneous display for routine application to particle suspensions and magnetically labeled biological cells. © 2016 International Society for Advancement of Cytometry.

  3. Isolation of technogenic magnetic particles

    Energy Technology Data Exchange (ETDEWEB)

    Catinon, Mickaël, E-mail: mickael.catinon@gmail.com [Laboratoire LECA, UMR 5553, Equipe Pollution, Environnement, Ecotoxicologie et Ecoremédiation, Univ. J. Fourier, 38041 Grenoble (France); Ayrault, Sophie, E-mail: sophie.ayrault@lsce.ispl.fr [Laboratoire des Sciences du Climat et de l' Environnement, UMR 8212, CEA-CNRS-UVSQ/IPSL, 91198 Gif-sur-Yvette (France); Boudouma, Omar, E-mail: boudouma@ccr.jussieu.fr [Service du MEB, UFR928, Université Pierre et Marie Curie, 75252 Paris VI (France); Bordier, Louise, E-mail: Louise.Bordier@lsce.ipsl.fr [Laboratoire des Sciences du Climat et de l' Environnement, UMR 8212, CEA-CNRS-UVSQ/IPSL, 91198 Gif-sur-Yvette (France); Agnello, Gregory, E-mail: contact@evinrude.fr [Evinrude, Espace St Germain, 38200 Vienne (France); Reynaud, Stéphane, E-mail: stephane.reynaud@ujf-grenoble.fr [Laboratoire LECA, UMR 5553, Equipe Pollution, Environnement, Ecotoxicologie et Ecoremédiation, Univ. J. Fourier, 38041 Grenoble (France); Tissut, Michel, E-mail: michel.tissut@ujf-grenoble.fr [Laboratoire LECA, UMR 5553, Equipe Pollution, Environnement, Ecotoxicologie et Ecoremédiation, Univ. J. Fourier, 38041 Grenoble (France)

    2014-03-01

    Technogenic magnetic particles (TMPs) emitted by various industrial sources, such as smelting plants, end up after atmospheric transfer on the soil surface. In the present study, we characterised the origin and composition of such particles emitted by a large iron smelting plant and deposited on particular substrates, namely tombstones, which act as a very interesting and appropriate matrix when compared to soil, tree bark, lichens or attic dust. The isolation and subsequent description of TMPs require a critical step of separation between different components of the sample and the magnetic particles; here, we described an efficient protocol that fulfils such a requirement: it resorts to water suspension, sonication, repeated magnetic extraction, sedimentation, sieving and organic matter destruction at 550 °C in some instances. The isolated TMPs displayed a noticeable crystalline shape with variable compositions: a) pure iron oxides, b) iron + Cr, Ni or Zn, and c) a complex structure containing Ca, Si, Mg, and Mn. Using Scanning Electron Microscope Energy Dispersive X-ray (SEM–EDX), we obtained profiles of various and distinct magnetic particles, which allowed us to identify the source of the TMPs. - Highlights: • The developed method offers a low-cost approach of large-scale dry deposition. • Tombstones are excellent supports for sampling these atmospheric deposits. • Smelted elements crystallise after cooling, giving typical technogenic magnetic particles (TMPs). • Coupling microscopic and bulk analyses allows identifying TMP origin. • Magnetic TMPs issued from steel industry were separated by a new technique.

  4. Biomedical applications of magnetic particles

    CERN Document Server

    Mefford, Thompson

    2017-01-01

    Magnetic particles are increasingly being used in a wide variety of biomedical applications. Written by a team of internationally respected experts, this book provides an up-to-date authoritative reference for scientists and engineers. The first section presents the fundamentals of the field by explaining the theory of magnetism, describing techniques to synthesize magnetic particles, and detailing methods to characterize magnetic particles. The second section describes biomedical applications, including chemical sensors and cellular actuators, and diagnostic applications such as drug delivery, hyperthermia cancer treatment, and magnetic resonance imaging contrast.

  5. Magnetic Particle Technology

    Science.gov (United States)

    Oliveira, Luiz C.A.; A. Rios, Rachel V.R.; Fabris, Jose D.; Lago, Rachel M.; Sapag, Karim

    2004-01-01

    An exciting laboratory environment is activated by the preparation and novel use of magnetic materials to decontaminate water through adsorption and magnetic removal of metals and organics. This uncomplicated technique is also adaptable to the possible application of adsorbents to numerous other environmental substances.

  6. [Construction of Lactobacillus rhamnosus GG particles surface display system].

    Science.gov (United States)

    Su, Runyu; Nie, Boyao; Yuan, Shengling; Tao, Haoxia; Liu, Chunjie; Yang, Bailiang; Wang, Yanchun

    2017-01-25

    To describe a novel particles surface display system which is consisted of gram-positive enhancer matrix (GEM) particles and anchor proteins for bacteria-like particles vaccines, we treated Lactobacillus rhamnosus GG bacteria with 10% heated-TCA for preparing GEM particles, and then identified the harvested GEM particles by electron microscopy, RT-PCR and SDS-PAGE. Meanwhile, Escherichia coli was induced to express hybrid proteins PA3-EGFP and P60-EGFP, and GEM particles were incubated with them. Then binding of anchor proteins were determined by Western blotting, transmission electron microscopy, fluorescence microscopy and spectrofluorometry. GEM particles preserved original size and shape, and proteins and DNA contents of GEM particles were released substantially. The two anchor proteins both had efficiently immobilized on the surface of GEM. GEM particles that were bounded by anchor proteins were brushy. The fluorescence of GEM particles anchoring PA3 was slightly brighter than P60, but the difference was not significant (P>0.05). GEM particles prepared from L. rhamnosus GG have a good binding efficiency with anchor proteins PA3-EGFP and P60-EGFP. Therefore, this novel foreign protein surface display system could be used for bacteria-like particle vaccines.

  7. Particles trajectories in magnetic filaments

    CERN Document Server

    Bret, Antoine

    2015-01-01

    The motion of a particle in a spatially harmonic magnetic field is a basic problem involved, for example, in the mechanism of formation of a collisionless shock. In such settings, it is generally reasoned that particles entering a Weibel generated turbulence are trapped inside it, provided their Larmor radius in the peak field is smaller than the field coherence length. The goal of this work is to put this heuristic conclusion on firm ground by studying, both analytically and numerically, such motion. A toy model is analyzed, consisting of a relativistic particle entering a region of space occupied by a spatially harmonic field. The particle penetrates the magnetic structure in a direction aligned with the magnetic filaments. Although the conclusions are not trivial, the main result is confirmed.

  8. Particles trajectories in magnetic filaments

    Energy Technology Data Exchange (ETDEWEB)

    Bret, A. [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain); Instituto de Investigaciones Energéticas y Aplicaciones Industriales, Campus Universitario de Ciudad Real, 13071 Ciudad Real (Spain)

    2015-07-15

    The motion of a particle in a spatially harmonic magnetic field is a basic problem involved, for example, in the mechanism of formation of a collisionless shock. In such settings, it is generally reasoned that particles entering a Weibel generated turbulence are trapped inside it, provided their Larmor radius in the peak field is smaller than the field coherence length. The goal of this work is to put this heuristic conclusion on firm ground by studying, both analytically and numerically, such motion. A toy model is analyzed, consisting of a relativistic particle entering a region of space occupied by a spatially harmonic field. The particle penetrates the magnetic structure in a direction aligned with the magnetic filaments. Although the conclusions are not trivial, the main result is confirmed.

  9. Magnetic guidance of charged particles

    Directory of Open Access Journals (Sweden)

    Dirk Dubbers

    2015-09-01

    Full Text Available Many experiments and devices in physics use static magnetic fields to guide charged particles from a source onto a detector, and we ask the innocent question: What is the distribution of particle intensity over the detector surface? One should think that the solution to this seemingly simple problem is well known. We show that, even for uniform guide fields, this is not the case, and we present analytical point spread functions (PSF for magnetic transport that deviate strongly from previous results. The “magnetic” PSF shows unexpected singularities, which were recently also observed experimentally, and which make detector response very sensitive to minute changes of position, field amplitude, or particle energy. In the field of low-energy particle physics, these singularities may become a source of error in modern high precision experiments, or may be used for instrument tests.

  10. Preparation of Panel and Charged Particles for Electrophoretic Display

    Science.gov (United States)

    Choi, Hyung Suk; Park, Jin Woo; Park, Lee Soon; Lee, Jung Kyung; Han, Yoon Soo; Kwon, Younghwan

    Studies on the formulation of photosensitive paste for transparent soft mold press (TSMP) method have been performed. With the optimum formulation of the photosensitive paste the box-type barrier rib with good flexibility and high solvent resistance was fabricated, suitable for the panel material of the electrophoretic display. Cationically-charged white particles were prepared by using TiO2 nanoparticles, silane coupling agent with amino groups, dispersant and acetic acid. The cationically charged TiO2 particles exhibited 74.09 mV of zeta potential and 3.11 × 10-5 cm2/Vs of mobility. Electrophoretic display fabricated with the charged TiO2 particles exhibited 10 V of low driving voltage and maximum contrast ratio (5.3/1) at 30 V.

  11. Traveling Wave Magnetic Particle Imaging

    OpenAIRE

    Vogel, Patrick

    2016-01-01

    Magnetic Particle Imaging (MPI) ist eine noch sehr junge Technologie unter den nicht-invasiven tomographischen Verfahren. Seit der ersten Veröffentlichung 2005 wurden einige Scannertypen und Konzepte vorgestellt, welche durch die Messung des Antwortsignals von superparamagnetischen Eisennanopartikeln (SPIOs) auf wechselnde Magnetfelder ein dreidi-mensionales Bild ihrer Verteilung berechnen können. Durch die direkte Messung des Tracers handelt es sich beim MPI um eine sehr sensitive und hochsp...

  12. Magnetic particle motion in a Poiseuille flow

    NARCIS (Netherlands)

    Haverkort, J.W.; et al, not CWI

    2009-01-01

    The manipulation of magnetic particles in a continuous flow with magnetic fields is central to several biomedical applications, including magnetic cell separation and magnetic drug targeting. A simplified twodimensional 2D equation describing the motion of particles in a planar Poiseuille flow is co

  13. Effective particle magnetic moment of multi-core particles

    Energy Technology Data Exchange (ETDEWEB)

    Ahrentorp, Fredrik; Astalan, Andrea; Blomgren, Jakob; Jonasson, Christian [Acreo Swedish ICT AB, Arvid Hedvalls backe 4, SE-411 33 Göteborg (Sweden); Wetterskog, Erik; Svedlindh, Peter [Department of Engineering Sciences, Uppsala University, Box 534, SE-751 21 Uppsala (Sweden); Lak, Aidin; Ludwig, Frank [Institute of Electrical Measurement and Fundamental Electrical Engineering, TU Braunschweig, D‐38106 Braunschweig Germany (Germany); IJzendoorn, Leo J. van [Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Westphal, Fritz; Grüttner, Cordula [Micromod Partikeltechnologie GmbH, D ‐18119 Rostock (Germany); Gehrke, Nicole [nanoPET Pharma GmbH, D ‐10115 Berlin Germany (Germany); Gustafsson, Stefan; Olsson, Eva [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg (Sweden); Johansson, Christer, E-mail: christer.johansson@acreo.se [Acreo Swedish ICT AB, Arvid Hedvalls backe 4, SE-411 33 Göteborg (Sweden)

    2015-04-15

    In this study we investigate the magnetic behavior of magnetic multi-core particles and the differences in the magnetic properties of multi-core and single-core nanoparticles and correlate the results with the nanostructure of the different particles as determined from transmission electron microscopy (TEM). We also investigate how the effective particle magnetic moment is coupled to the individual moments of the single-domain nanocrystals by using different measurement techniques: DC magnetometry, AC susceptometry, dynamic light scattering and TEM. We have studied two magnetic multi-core particle systems – BNF Starch from Micromod with a median particle diameter of 100 nm and FeraSpin R from nanoPET with a median particle diameter of 70 nm – and one single-core particle system – SHP25 from Ocean NanoTech with a median particle core diameter of 25 nm.

  14. Investigations on the magnetization behavior of magnetic composite particles

    Science.gov (United States)

    Eichholz, Christian; Knoll, Johannes; Lerche, Dietmar; Nirschl, Hermann

    2014-11-01

    In life sciences the application of surface functionalized magnetic composite particles is establishing in diagnostics and in downstream processing of modern biotechnology. These magnetic composite particles consist of non-magnetic material, e.g. polystyrene, which serves as a matrix for the second magnetic component, usually colloidal magnetite. Because of the multitude of magnetic cores these magnetic beads show a complex magnetization behavior which cannot be described with the available approaches for homogeneous magnetic material. Therefore, in this work a new model for the magnetization behavior of magnetic composite particles is developed. By introducing an effective magnetization and considering an overall demagnetization factor the deviation of the demagnetization of homogeneously magnetized particles is taken into account. Calculated and experimental results show a good agreement which allows for the verification of the adapted model of particle magnetization. Besides, a newly developed magnetic analyzing centrifuge is used for the characterization of magnetic composite particle systems. The experimental results, also used for the model verification, give both, information about the magnetic properties and the interaction behavior of particle systems. By adding further components to the particle solution, such as salts or proteins, industrial relevant systems can be reconstructed. The analyzing tool can be used to adapt industrial processes without time-consuming preliminary tests with large samples in the process equipments.

  15. Evaluation of magnetic heating of asymmetric magnetite particles

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Xin [School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing (China); Sabyrov, Kairat [Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States (United States); Klein, Todd [Department of Electrical Engineering, University of Minnesota, Minneapolis, MN 55455 (United States); Lee Penn, R. [Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States (United States); Wiedmann, Timothy S., E-mail: wiedm001@umn.edu [Department of Pharmaceutics, University of Minnesota, Minneapolis, MN 55455 (United States)

    2015-05-01

    Characterization and theoretical description of relatively large (>100 nm), asymmetric magnetic particles remain of interest particularly for applications to the mechanical damage of cells. In this work, we have examined the properties of three types of magnetite, Fe{sub 3}O{sub 4}, particles that were prepared by hydrogen reduction of hematite, α-Fe{sub 2}O{sub 3}. Transmission electron microscopy was used to measure the size and aspect ratio (AR), which were 1.8, 3.4 and 6.6, and all displayed magnetic hysteresis with corresponding saturation magnetization values of 65, 47, and 26 emu/g, respectively. With application of an alternating magnetic field to low concentrations, the temperature increased linearly with time, and the specific loss power (SLP) increased with increasing aspect ratio with values of 11.8, 24, and 26.8 W/g. The SLP increased linearly with the square of the applied magnetic field at low concentrations, but deviations were noted for high concentrations of the 2.4 and 6.6 AR particles. SLP was also dependent on frequency, but the functional relationship was not reliably determined. In consideration of the possible heating mechanisms, none provided a satisfactorily explanation for all types of particles. While these particles are not satisfactory for magnetic hyperthermia, they may have promise for causing cell death by magnetically inducing the particles to physically rotate or vibrate. - Highlights: • Magnetite particles were prepared with dimension of 93×52 nm, 165×48 nm and 207×32 nm. • Particles had hysteresis with M{sub s} of 65 (AR=1.8), 47 (AR=3.4), and 26 emu/g (AR=6.6). • Specific loss power indicated particle–particle interactions. • SLP increased with the square of the magnetic field strength at low concentration. • Particle may have promise to induce cell death by physical rotation.

  16. Preparation and application of streptavidin magnetic particles

    Institute of Scientific and Technical Information of China (English)

    ZHANG ZhiFeng; ZHU HongLi; TANG YiTong; CUI Ting; GENG TingTing; CHEN Chao; CUI YaLi

    2007-01-01

    Two kinds of streptavidin magnetic particles, namely streptavidin GoldMag particles and streptavidin amino terminal particles were prepared by the methods of physical adsorption and covalent interaction respectively. The streptavidin coated on magnetic particle surface, crucial to many applications, was greatly influenced by the choice of the different buffer. Compared with Dynalbeads(r)M-270 streptavidin, the binding capacity for biotin of different streptavidin magnetic particles was determined by enzyme inhibition method, and the coupling capacity and activity of biotinylated oligonucleotide on their surface were also analyzed. The results indicated that the streptavidin GoldMag particle prepared by physical adsorption was stable in STE (NaCl-Tris-EDTA) buffer that was frequently used in nucleic acid hybridization and detection. The streptavidin amino terminal particles prepared by covalent interaction could be used both in STE buffer and PBS (phosphate buffered saline) buffer. The biotin binding capacity for 1 mg of streptavidin GoldMag particles and streptavidin amino terminal particles was 4950 and 5115 pmol respectively. The capacity of biotinylated oligonucleotide (24 bp) coupled on 1 mg of GoldMag and amino terminal magnetic particles was 2839 and 2978 pmol separately. These data were about 6-7 times higher than those of Dynabeads(r)M-270 streptavidin. The hybridization results with FITC-labeled complementary probe on magnetic particle surface demonstrated that the oligonucleotide coupled on streptavidin magnetic particles had high biological activity.

  17. Preparation and application of streptavidin magnetic particles

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Two kinds of streptavidin magnetic particles,namely streptavidin GoldMag particles and streptavidin amino terminal particles were prepared by the methods of physical adsorption and covalent interaction respectively.The streptavidin coated on magnetic particle surface,crucial to many applications,was greatly influenced by the choice of the different buffer.Compared with DynalbeadsM-270 streptavidin, the binding capacity for biotin of different streptavidin magnetic particles was determined by enzyme inhibition method,and the coupling capacity and activity of biotinylated oligonucleotide on their sur- face were also analyzed.The results indicated that the streptavidin GoldMag particle prepared by physical adsorption was stable in STE(NaCl-Tris-EDTA)buffer that was frequently used in nucleic acid hybridization and detection.The streptavidin amino terminal particles prepared by covalent interaction could be used both in STE buffer and PBS(phosphate buffered saline)buffer.The biotin binding ca- pacity for 1 mg of streptavidin GoldMag particles and streptavidin amino terminal particles was 4950 and 5115 pmol respectively.The capacity of biotinylated oligonucleotide(24 bp)coupled on 1 mg of GoldMag and amino terminal magnetic particles was 2839 and 2978 pmol separately.These data were about 6-7 times higher than those of DynabeadsM-270 streptavidin.The hybridization results with FITC-labeled complementary probe on magnetic particle surface demonstrated that the oligonucleotide coupled on streptavidin magnetic particles had high biological activity.

  18. Guiding plant virus particles to integrin-displaying cells

    Science.gov (United States)

    Hovlid, Marisa L.; Steinmetz, Nicole F.; Laufer, Burkhardt; Lau, Jolene L.; Kuzelka, Jane; Wang, Qian; Hyypiä, Timo; Nemerow, Glen R.; Kessler, Horst; Manchester, Marianne; Finn, M. G.

    2012-05-01

    Viral nanoparticles (VNPs) are structurally regular, highly stable, tunable nanomaterials that can be conveniently produced in high yields. Unmodified VNPs from plants and bacteria generally do not show tissue specificity or high selectivity in binding to or entry into mammalian cells. They are, however, malleable by both genetic and chemical means, making them useful scaffolds for the display of large numbers of cell- and tissue-targeting ligands, imaging moieties, and/or therapeutic agents in a well-defined manner. Capitalizing on this attribute, we modified the genetic sequence of the Cowpea mosaic virus (CPMV) coat protein to display an RGD oligopeptide sequence derived from human adenovirus type 2 (HAdV-2). Concurrently, wild-type CPMV was modified via NHS acylation and Cu(i)-catalyzed azide-alkyne cycloaddition (CuAAC) chemistry to attach an integrin-binding cyclic RGD peptide. Both types of particles showed strong and selective affinity for several different cancer cell lines that express RGD-binding integrin receptors.Viral nanoparticles (VNPs) are structurally regular, highly stable, tunable nanomaterials that can be conveniently produced in high yields. Unmodified VNPs from plants and bacteria generally do not show tissue specificity or high selectivity in binding to or entry into mammalian cells. They are, however, malleable by both genetic and chemical means, making them useful scaffolds for the display of large numbers of cell- and tissue-targeting ligands, imaging moieties, and/or therapeutic agents in a well-defined manner. Capitalizing on this attribute, we modified the genetic sequence of the Cowpea mosaic virus (CPMV) coat protein to display an RGD oligopeptide sequence derived from human adenovirus type 2 (HAdV-2). Concurrently, wild-type CPMV was modified via NHS acylation and Cu(i)-catalyzed azide-alkyne cycloaddition (CuAAC) chemistry to attach an integrin-binding cyclic RGD peptide. Both types of particles showed strong and selective affinity

  19. Particle acceleration at a reconnecting magnetic separator

    CERN Document Server

    Threlfall, J; Parnell, C E; Oskoui, S Eradat

    2014-01-01

    While the exact acceleration mechanism of energetic particles during solar flares is (as yet) unknown, magnetic reconnection plays a key role both in the release of stored magnetic energy of the solar corona and the magnetic restructuring during a flare. Recent work has shown that special field lines, called separators, are common sites of reconnection in 3D numerical experiments. To date, 3D separator reconnection sites have received little attention as particle accelerators. We investigate the effectiveness of separator reconnection as a particle acceleration mechanism for electrons and protons. We study the particle acceleration using a relativistic guiding-centre particle code in a time-dependent kinematic model of magnetic reconnection at a separator. The effect upon particle behaviour of initial position, pitch angle and initial kinetic energy are examined in detail, both for specific (single) particle examples and for large distributions of initial conditions. The separator reconnection model contains ...

  20. Modeling of magnetic particle suspensions for simulations

    CERN Document Server

    Satoh, Akira

    2017-01-01

    The main objective of the book is to highlight the modeling of magnetic particles with different shapes and magnetic properties, to provide graduate students and young researchers information on the theoretical aspects and actual techniques for the treatment of magnetic particles in particle-based simulations. In simulation, we focus on the Monte Carlo, molecular dynamics, Brownian dynamics, lattice Boltzmann and stochastic rotation dynamics (multi-particle collision dynamics) methods. The latter two simulation methods can simulate both the particle motion and the ambient flow field simultaneously. In general, specialized knowledge can only be obtained in an effective manner under the supervision of an expert. The present book is written to play such a role for readers who wish to develop the skill of modeling magnetic particles and develop a computer simulation program using their own ability. This book is therefore a self-learning book for graduate students and young researchers. Armed with this knowledge,...

  1. Magnetic Particle Technique: Lab Case of CAMAN

    Directory of Open Access Journals (Sweden)

    Sonia Ruth Rincón Urbina

    2015-10-01

    Full Text Available This article presents the general procedure for the use of the technique of magnetic particles; generally describes the main characteristics of the test and inspection procedure from CAMAN Lab developed at the Graduate School of the Colombian Air Force. The method used in the research and development of the project was documentary, in order to establish the rules and regulations required for certification of the magnetic particles technique in nondestructive testing laboratory by the Aeronautical Authority. Finally, based on the data analysis, an Inspection Procedure Manual was developed in order to certify the magnetic particles technique.

  2. EXTREMELY LOW FREQUENCY MAGNETIC FIELD SUSCEPTIBILITY OF VISUAL DISPLAY UNITS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Extremely low frequency (ELF) magnetic field susceptibility is an index of visual display unit (VDU) quality and performance. This paper provided field measured data on the susceptibility for a large variety of VDUs. A test rig was built to study the susceptibility of VDUs to magnetic fields at fundamental and third harmonic frequencies. It was found that the susceptibility level is largely dependent on refresh rate of the VDU and the orientation of the external ELF field. It was also found that the VDU susceptibility is significantly increased in the presence of harmonic frequency magnetic fields. About 30% of the tested samples have susceptibility levels higher than that stated in IEC 1000-4-8 standard.

  3. Alignment of magnetic uniaxial particles in a magnetic field: Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Golovnia, O.A., E-mail: golovnya@imp.uran.ru [Institute of Metal Physics, Str. S. Kovalevskoy, 18, 620990 Ekaterinburg (Russian Federation); Popov, A.G [Institute of Metal Physics, Str. S. Kovalevskoy, 18, 620990 Ekaterinburg (Russian Federation); Sobolev, A.N. [South Ural State University (National Research University), av. Lenina, 76, 454080 Chelyabinsk (Russian Federation); Hadjipanayis, G.C. [Department of Physics and Astronomy, University of Delaware, 217 Sharp Lab, Newark, DE 19716 (United States)

    2014-09-01

    The numerical investigations of the process of alignment of magnetically uniaxial Nd–Fe–B powders in an applied magnetic field were carried out using the discrete element method (DEM). It is shown that magnetic alignment of ensemble of spherical particles provides extremely high degree of alignment, which is achieved in low magnetic fields. A model of formation of anisotropic particles as a combination of spherical particles is suggested. The influence of the shape anisotropy and friction coefficient on the alignment degree was analyzed. The increase in the friction coefficient leads to a decrease in the alignment degree; the simulation results are in qualitative agreement with experimental dependences. It is shown that in magnetic fields higher than 5 T, the calculated field dependences of the alignment degree quantitatively render the experimental data. The increase of about 6% in the alignment degree in the experiments with addition of internal lubricant can be explained by the decrease of 14% in friction coefficient. - Highlights: • We simulate the magnetic alignment of ensemble of Nd–Fe–B spherical uniaxial particles. • Anisotropic particles as a combination of spherical particles are constructed. • Influence of the particle shape anisotropy and friction on the alignment is analyzed. • We compare calculated and experimental data on field dependence of magnetic alignment. • The results render the experimental dependence.

  4. Magnetic tweezers for manipulation of magnetic particles in single cells

    Science.gov (United States)

    Ebrahimian, H.; Giesguth, M.; Dietz, K.-J.; Reiss, G.; Herth, S.

    2014-02-01

    Magnetic tweezers gain increasing interest for applications in biology. Here, a setup of magnetic tweezers is introduced using micropatterned conducting lines on transparent glass slides. Magnetic particles of 1 μm diameter were injected in barley cell vacuoles using a microinject system under microscopic control. Time dependent tracking of the particles after application of a magnetic field was used to determine the viscosity of vacuolar sap in vivo relative to water and isolated vacuolar fluid. The viscosity of vacuolar sap in cells was about 2-fold higher than that of extracted vacuolar fluid and 5 times higher than that of water.

  5. Self-assembly of smallest magnetic particles.

    Science.gov (United States)

    Mehdizadeh Taheri, Sara; Michaelis, Maria; Friedrich, Thomas; Förster, Beate; Drechsler, Markus; Römer, Florian M; Bösecke, Peter; Narayanan, Theyencheri; Weber, Birgit; Rehberg, Ingo; Rosenfeldt, Sabine; Förster, Stephan

    2015-11-24

    The assembly of tiny magnetic particles in external magnetic fields is important for many applications ranging from data storage to medical technologies. The development of ever smaller magnetic structures is restricted by a size limit, where the particles are just barely magnetic. For such particles we report the discovery of a kind of solution assembly hitherto unobserved, to our knowledge. The fact that the assembly occurs in solution is very relevant for applications, where magnetic nanoparticles are either solution-processed or are used in liquid biological environments. Induced by an external magnetic field, nanocubes spontaneously assemble into 1D chains, 2D monolayer sheets, and large 3D cuboids with almost perfect internal ordering. The self-assembly of the nanocubes can be elucidated considering the dipole-dipole interaction of small superparamagnetic particles. Complex 3D geometrical arrangements of the nanodipoles are obtained under the assumption that the orientation of magnetization is freely adjustable within the superlattice and tends to minimize the binding energy. On that basis the magnetic moment of the cuboids can be explained.

  6. Magnetic iron particles with high magnetization useful for immunoassay

    Energy Technology Data Exchange (ETDEWEB)

    Tokoro, Hisato [Hitachi Metals, Ltd., Advanced Electronics Research Laboratory, 5200 Mikajiri, Kumagaya, Saitama 360-0843 (Japan)], E-mail: hisato_tokoro@hitachi-metals.co.jp; Nakabayashi, Takashi; Fujii, Shigeo [Hitachi Metals, Ltd., Advanced Electronics Research Laboratory, 5200 Mikajiri, Kumagaya, Saitama 360-0843 (Japan); Zhao Hong; Haefeli, Urs O. [Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC V6T 1Z3 (Canada)

    2009-05-15

    TiO{sub 2}-encapsulated metallic Fe particles (Ti-O/Fe) were synthesized through a solid phase reaction. The Ti-O/Fe particles were non-toxic to tumor cells in a cell viability assay. After silica coating using a sol-gel method, streptavidin was covalently bound onto the Ti-O/Fe particles. Thus produced HMMI particles showed higher magnetization (114 Am{sup 2}/kg) and a larger specific surface area (15 m{sup 2}/g) than conventional streptavidin-immobilized magnetite particles. The high magnetization allowed for rapid magnetic separation, while the additional large specific surface area improved the detection of the adiponectin antigen both in terms of extended detection range and higher assay speed.

  7. MDF: Magnetic Particle Imaging Data Format

    CERN Document Server

    Knopp, Tobias; Bringout, Gael; Ahlborg, Mandy; Rahmer, Jürgen; Hofmann, Martin

    2016-01-01

    Magnetic particle imaging (MPI) is a tomographic method to determine the spatial distribution of magnetic nanoparticles. In this document a file format for the standardized storage of MPI data is introduced. The aim of the Magnetic Particle Imaging Data Format (MDF) is to provide a coherent way of exchanging MPI data acquired with different MPI scanners worldwide. The focus of the file format is on sequence parameters, raw measurement data, calibration data, and reconstruction data. The format is based on the hierarchical document format (HDF) in version 5 (HDF5).

  8. Metallic magnetic bolometers for particle detection

    Energy Technology Data Exchange (ETDEWEB)

    Bandler, S.R.; Enss, C.; Lanou, R.E.; Maris, H.J.; More, T.; Porter, F.S.; Seidel, G.M. (Brown Univ., Providence, RI (United States))

    1993-11-01

    The magnetization of localized spins in metals is discussed as a sensor for the low temperature calorimetric detection of particles. The magnetization of localized paramagnetic ions in metals can be used as a very sensitive sensor for the calorimetric detection of particles at low temperatures. The strong coupling of the localized spins to the conduction electrons results in very fast thermal equilibration between the two systems. Even though the concentration of spins must be kept small in metals to avoid spin-spin coupling by indirect exchange, the metallic magnetic bolometer can achieve very high sensitivities. In general, the sensitivity increases very rapidly with decreasing temperature.

  9. Nonthermal Particle Acceleration in Magnetic Reconnection

    Science.gov (United States)

    Guo, Fan; Li, Hui; Zhang, Haocheng; Daughton, William; Liu, Yi-Hsin; Lloyd-Ronning, Nicole

    2017-08-01

    Magnetic reconnection is a leading mechanism for dissipating magnetic energy and accelerating nonthermal particles in Poynting-flux-dominated flows. In this study, we investigate nonthermal particle acceleration during magnetic reconnection in a magnetically dominated plasma using fully kinetic simulations. We have studied the magnetically dominated regime by varying σe = 103-105 and mass ratios. The results demonstrate that reconnection quickly establishes power-law energy distributions for both electrons and ions within several (2-3) light-crossing times. For the cases with periodic boundary conditions, the power-law index is 1 < p < 2 for both electrons and ions. We study particle acceleration in magnetic reconnection via large-scale 3D kinetic simulations to examine several effects that may be important, including pre-existing fluctuations, kink and secondary tearing instabilities, and open boundary conditions. The results show that particle acceleration in reconnection layers is surprisingly robust despite the development of 3D turbulence and instabilities. The main acceleration mechanism is a Fermi-like acceleration through the drift motions of charged particles. We discuss the implication of this study in the context of Poynting-flux dominated jets and pulsar winds, especially the applications for explaining nonthermal high-energy emissions.

  10. Superconducting Magnets for Particle Accelerators

    CERN Document Server

    Rossi, L

    2012-01-01

    Superconductivity has been the most influential technology in the field of accelerators in the last 30 years. Since the commissioning of the Tevatron, which demonstrated the use and operability of superconductivity on a large scale, superconducting magnets and rf cavities have been at the heart of all new large accelerators. Superconducting magnets have been the invariable choice for large colliders, as well as cyclotrons and large synchrotrons. In spite of the long history of success, superconductivity remains a difficult technology, requires adequate R&D and suitable preparation, and has a relatively high cost. Hence, it is not surprising that the development has also been marked by a few setbacks. This article is a review of the main superconducting accelerator magnet projects; it highlights the main characteristics and main achievements, and gives a perspective on the development of superconducting magnets for the future generation of very high energy colliders.

  11. Magnetic normal modes in nano-particles

    Energy Technology Data Exchange (ETDEWEB)

    Grimsditch, M. [Materials Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States)]. E-mail: grimsditch@anl.gov; Giovannini, L. [Dipartimento di Fisica, Universita di Ferrara and Istituto Nazionale per la Fisica della Materia, Via del Paradiso 12, I-44100 Ferrara (Italy); Montoncello, F. [Dipartimento di Fisica, Universita di Ferrara and Istituto Nazionale per la Fisica della Materia, Via del Paradiso 12, I-44100 Ferrara (Italy); Nizzoli, F. [Dipartimento di Fisica, Universita di Ferrara and Istituto Nazionale per la Fisica della Materia, Via del Paradiso 12, I-44100 Ferrara (Italy); Leaf, G. [Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Kaper, H. [Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Karpeev, D. [Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2004-12-31

    We have recently developed two methods to calculate the magnetic normal modes of a magnetic nano-particle. One of the methods is based on a conventional micromagnetic approach in which the time evolution of the magnetization of each cell is monitored. After filtering in frequency domain, the magnetic normal modes can be reconstructed. The second method is based on solving the same micromagneitc system in a dynamical matrix formulation. The results of the two methods, applied to a rectangular parallelepiped of Fe, will be presented and compared.

  12. Field free line magnetic particle imaging

    CERN Document Server

    Erbe, Marlitt

    2014-01-01

    Marlitt Erbe provides a detailed introduction into the young research field of Magnetic Particle Imaging (MPI) and field free line (FFL) imaging in particular. She derives a mathematical description of magnetic field generation for FFL imaging in MPI. To substantiate the simulation studies on magnetic FFL generation with a proof-of-concept, the author introduces the FFL field demonstrator, which provides the world's first experimentally generated rotated and translated magnetic FFL field complying with the requirements for FFL reconstruction. Furthermore, she proposes a scanner design of consi

  13. Extended particle-based simulation for magnetic-aligned compaction of hard magnetic particles

    Energy Technology Data Exchange (ETDEWEB)

    Soda, Rikio; Takagi, Kenta; Ozaki, Kimihiro, E-mail: r-soda@aist.go.jp

    2015-12-15

    In order to understand the magnetic-aligned compaction process, we develop a three-dimensional (3D) discrete element method for simulating the motion of hard magnetic particles subjected to strong compression and magnetic fields. The proposed simulation model also considers the exact magnetic force involved via the calculation of the magnetic moment. First, to validate the simulation model, single-action compaction in the absence of a magnetic field was calculated. The calculated compaction curves are in good quantitative agreement with experimental ones. Based on this simulation model, the alignment behavior of Nd–Fe–B particles during compression under the application of a static magnetic field. The developed simulation model enables the visualization of particle behavior including the misorientation of the magnetization easy axis, which provided the quantitative relationships between applied pressure and particle misorientation. - Highlights: • A practical 3D DEM simulation technique for magnetic-aligned compaction was developed. • An extended simulation model was introduced for hard magnetic particles. • Magnetic-aligned compaction was simulated using the developed simulation model.

  14. Magnetic particle mixing with magnetic micro-convection for microfluidics

    Science.gov (United States)

    Kitenbergs, Guntars; E¯rglis, Kaspars; Perzynski, Régine; Cěbers, Andrejs

    2015-04-01

    In this paper we discuss the magnetic micro-convection phenomenon as a tool for mixing enhancement in microfluidics systems in cases when one of the miscible fluids is a magnetic particle colloid. A system of a water-based magnetic fluid and water is investigated experimentally under homogeneous magnetic field in a Hele-Shaw cell. Subsequent image analysis both qualitatively and quantitatively reveals the high enhancement of mixing efficiency provided by this method. The mixing efficiency dependence on the magnetic field and the physical limits is discussed. A suitable model for a continuous-flow microfluidics setup for mixing with magnetic micro-convection is also proposed and justified with an experiment. In addition, possible applications in improving the speed of ferrohydrodynamic sorting and magnetic label or selected tracer mixing in lab on a chip systems are noted.

  15. Surface magnetism of ferromagnetic ultrafine particles

    Institute of Scientific and Technical Information of China (English)

    ZHEN; Peng(甄鹏); LI; Hua(李华); HU; Weijun(胡维军); MEI; Liangmo(梅良模)

    2002-01-01

    The electronic structures and atomic magnetic moments of Nin clusters ( n = 2-6) have been studied. Compared with crystalline nickel, some clusters increase obviously in magnetism; some decrease obviously; and some show ferrimagnetism. The symmetry of clusters has great effect on magnetic moment. If they are similar in symmetry, the clusters are similar in magnetic moment. The magnetic moment for small clusters does not seem to increase or decrease monotonically with the change in their size, because adding or removing one atom may fully change the symmetry of small clusters. As the surface layer of ultrafine particles is made of many different polyhedrons with low symmetry and the alignment of the polyhedrons is complicated, the whole surface layer presents shortrange order. The calculated results explain the abnormal phenomena about surface magnetism that have been in existence for a long time.

  16. Cobalt nano-particles for application in magnetic data storage

    CERN Document Server

    Holmes, B M

    2002-01-01

    Particulate magnetic media has been produced through a novel technique, whereby the rapid thermal decomposition of reactively sputtered pre-cursor thin films of cobalt nitride results in a two dimensional array of hcp cobalt particles. The samples produced have been examined and characterised, magnetically, optically, and magneto-optically with respect to the thickness of the precursor films of CoN. Samples with a volume thickness of less than 20A have been found to fall within the superparamagnetic size range, whilst samples thicker than this are found to consist of single domain ferromagnetic particles. The media displays magnetic properties that are greatly enhanced compared to those of bulk Co. The diameters of the particles have been found to be approximately equal to the optimum size range required for high-density magnetic storage. An analysis of the magnetic properties of a core set of samples has enabled a value to be obtained for both the thickness of the oxide shell as well as the effective anisotr...

  17. Permanent magnet system to guide superparamagnetic particles

    Science.gov (United States)

    Baun, Olga; Blümler, Peter

    2017-10-01

    A new concept of using permanent magnet systems for guiding superparamagnetic nano-particles on arbitrary trajectories over a large volume is proposed. The basic idea is to use one magnet system which provides a strong, homogeneous, dipolar magnetic field to magnetize and orient the particles, and a second constantly graded, quadrupolar field, superimposed on the first, to generate a force on the oriented particles. In this configuration the motion of the particles is driven predominantly by the component of the gradient field which is parallel to the direction of the homogeneous field. As a result, particles are guided with constant force and in a single direction over the entire volume. The direction is simply adjusted by varying the angle between quadrupole and dipole. Since a single gradient is impossible due to Gauß' law, the other gradient component of the quadrupole determines the angular deviation of the force. However, the latter can be neglected if the homogeneous field is stronger than the local contribution of the quadrupole field. A possible realization of this idea is a coaxial arrangement of two Halbach cylinders. A dipole to evenly magnetize and orient the particles, and a quadrupole to generate the force. The local force was calculated analytically for this particular geometry and the directional limits were analyzed and discussed. A simple prototype was constructed to demonstrate the principle in two dimensions on several nano-particles of different size, which were moved along a rough square by manual adjustment of the force angle. The observed velocities of superparamagnetic particles in this prototype were always several orders of magnitude higher than the theoretically expected value. This discrepancy is attributed to the observed formation of long particle chains as a result of their polarization by the homogeneous field. The magnetic moment of such a chain is then the combination of that of its constituents, while its hydrodynamic radius

  18. Modeling of magnetic material displaying magnetic aftereffect with slow decay rates

    Energy Technology Data Exchange (ETDEWEB)

    Gu, S., E-mail: shuogu@gwmail.gwu.edu [Department of Electrical and Computer Engineering, George Washington University, Washington DC 20052 (United States); Jin, Y.; Chen, P.; Yan, C.; Della Torre, E.; Bennett, L.H. [Department of Electrical and Computer Engineering, George Washington University, Washington DC 20052 (United States)

    2012-05-01

    For magnetic materials that display slow decay rates, the entire relaxation process cannot be observed experimentally within a reasonable time interval. While magnetic aftereffect behavior has been understood and analyzed quantitatively in general, the important parameters of magnetic materials with slow decay cannot be easily extracted. We present comprehensive experimental characterization of time, field, and temperature dependence of magnetic properties of a magnetic nanocomposite, which exhibits slow decay. Based on the measurement results and previously developed Preisach-Arrhenius model, we propose an analytical model that can predict the shape of the entire aftereffect curves at different temperatures with only the major hysteresis loop and one aftereffect curve at a specific holding field within the region of interest. The model is validated with both simulated data and measured data. This model allows the derivation of an analytical formula for the time variation of the magnetization based on a Gaussian distribution.

  19. Structure organization and magnetic properties of microscale ferrogels: The effect of particle magnetic anisotropy

    Science.gov (United States)

    Ryzhkov, Aleksandr V.; Melenev, Petr V.; Balasoiu, Maria; Raikher, Yuriy L.

    2016-08-01

    The equilibrium structure and magnetic properties of a ferrogel object of small size (microferrogel(MFG)) are investigated by coarse-grained molecular dynamics. As a generic model of a microferrogel (MFG), a sample with a lattice-like mesh is taken. The solid phase of the MFG consists of magnetic (e.g., ferrite) nanoparticles which are mechanically linked to the mesh making some part of its nodes. Unlike previous models, the finite uniaxial magnetic anisotropy of the particles, as it is the case for real ferrogels, is taken into account. For comparison, two types of MFGs are considered: MFG-1, which dwells in virtually non-aggregated state independently of the presence of an external magnetic field, and MFG-2, which displays aggregation yet under zero field. The structure states of the samples are analyzed with the aid of angle-resolved radial distribution functions and cluster counts. The results reveal the crucial role of the matrix elasticity on the structure organization as well as on magnetization of both MFGs. The particle anisotropy, which plays insignificant role in MFG-1 (moderate interparticle magnetodipole interaction), becomes an important factor in MFG-2 (strong interaction). There, the restrictions imposed on the particle angular freedom by the elastic matrix result in notable diminution of the particle chain lengths as well as the magnetization of the sample. The approach proposed enables one to investigate a large variety of MFGs, including those of capsule type and to purposefully choose the combination of their magnetoelastic parameters.

  20. An Educational Display of the Solar Magnetic Cycle: Year 2

    Science.gov (United States)

    Jones, H. P.; Gearen, M. V.; Jacoby, S. H.

    1999-05-01

    We are developing an educational module to improve student and public understanding of the Sun's magnetic cycle. The instructional package features a CDROM compatible with most personal computers available in the home or classroom with a day-by-day record of an entire magnetic cycle as recorded in magnetograms from the National Solar Observatory Kitt Peak Vacuum Telescope (NSO/KPVT) near Tucson, AZ. These data have in fact been crucial to developing our present understanding of the solar cycle and its terrestrial effects. In the second year of the project, we have loaded the data to compact disks both as individual "gif" files for inspection and analysis and as QuickTime movies, have prepared the first version of the accompanying textual material, and are developing macros to aid extraction of information from the data for various laboratory exercises. We will display samples of these images and movies, and will furnish copies of the compact disks and accompanying textual material for testing and comment.

  1. Toner Display Based on Movement of Tribo-electrically Charged Particles

    Institute of Scientific and Technical Information of China (English)

    Takashi Kitamura

    2004-01-01

    The mechanism of toner display based on an electrical movement of black and white charged particles has been investigated. Two kinds of particles of black and white charged in the different electric polarity are enclosed in two ITO transparent electrodes using an insulating spacer. The particle movement is controlled by the external electric field applied between two transparent electrodes. The black toner is adhered on the electrode by an electrostatic force across the CTL to display a black image. The toners can be put back to the counter electrode by applying a reverse electric field, and a white image is formed. The black and white solid images are displayed by the switch of polarity of applied voltage in toner display cell. The polarity of charge and the value of charge to mass ratio of two particles were measured by observation of the particle separation on the surface-type electrodes and using q/m meter, respectively.

  2. Magnetic properties of nano-composite particles

    Science.gov (United States)

    Xu, Xia

    Chemical synthesis routes for hollow spherical BaFe12O 19, hollow mesoporous spherical BaFe12O19, worm-shape BaFe12O19 and FeCo particles were developed. These structured particles have great potentials for the applications including magnetic recording medium, catalyst support, and energy storage. Magnetically exchange coupled hard/soft SrFe12O19/FeCo and MnBi/FeCo composites were synthesized through a newly proposed process of magnetic self-assembly. These exchange coupled composites can be potentially used as rare-earth free permanent magnets. Hollow spherical BaFe12O19 particles (shell thickness ˜5 nm) were synthesized from eth-ylene glycol assisted spray pyrolysis. Hollow mesoporous spherical BaFe12O19 particles (shell thickness ˜100 nm) were synthesized from ethanol assisted spray pyrolysis, followed by alkaline ethylene glycol etching at 185 °C. An alpha-Fe2O3 and BaCO3 nanoparticle mixture was synthesized with reverse microemulsion, followed by annealing at 900 °C for 2 hours to get worm-shape BaFe 12O19 particles, which consisted of 3-7 stacked hexagonal plates. FeCo nanoparticles were synthesized by reducing FeCl2 and CoCl2 in diphenyl ether with n-butyllithium at 200 °C in an inert gas environment. The surfactant of oleic acid was used in the synthesis to make particles well dispersed in nonpolar solvents (such as hexane). SrFe12O19/FeCo core/shell particles were prepared through a magnetic self-assembly process. The as-synthesized soft FeCo nanoparticles were magnetically attracted by hard SrFe12O19 parti-cles, forming a SrFe12O19/FeCo core/shell structure. The magnetic self-assembly mechanism was confirmed by applying alternating-current demagnetization to the core/shell particles, which re-sulted in a separation of SrFe 12O19 and FeCo particles. MnBi/FeCo composites were synthesized, and the exchange coupling between MnBi and FeCo phases was demonstrated by smooth magnetic hysteresis loop of MnBi/FeCo composites. The thermal stability of Mn

  3. Particle collider magnet self-destructs

    CERN Multimedia

    Higgins, Alexander G

    2007-01-01

    "A 43-foot-long magnet for the world's largest particle collider broke "with a loud band and a cloud of dust" during a high-pressure test, and officils said Tuesday they are working to find a replacement part." (1 page)

  4. Characterization of composite particles responsive to electric and magnetic fields

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xiaopeng; GUO Hongxia

    2004-01-01

    The multilayer particles with responses to electric and magnetic fields are a prerequisite for particles assembled under external fields. Three routes to produce particles responsive to electric and magnetic fields are presented in this article. The size and morphology, properties as well as the electric-magnetic responses of three kinds of particles are comparatively discussed. This will provide a useful basis for the control of the behavior of the particles in suspensions by external electric and magnetic fields.

  5. Second International Workshop on Magnetic Particle Imaging

    CERN Document Server

    Borgert, Jörn; Magnetic Particle Imaging : A Novel SPIO Nanoparticle Imaging Technique

    2012-01-01

    Magnetic Particle Imaging (MPI) is a novel imaging modality. In MPI superparamagnetic iron oxide nanoparticles are used as tracer materials. The volume is the proceeding of the 2nd international workshop on magnetic particle imaging (IWMPI). The workshop aims at covering the status and recent developments of both, the instrumentation and the tracer material, as each of them is equally important in designing a well performing MPI. For instance, the current state of the art in magnetic coil design for MPI is discussed. With a new symmetrical arrangement of coils, a field-free line (FFL) can be produced that promises a significantly higher sensitivity compared with the standard arrangement for a FFP. Furthermore, the workshop aims at presenting results from phantom and pre-clinical studies.

  6. Glassy behavior in magnetic fine particles

    CERN Document Server

    Muro, M G D; Labarta, A

    2000-01-01

    A detailed study of the static and dynamic magnetic properties of nanocrystalline barium hexaferrite powder was done. Particles of about 10 nm diameter exhibit the main features attributed to glassy behavior. Different results make evident the presence of strong interactions in the studied system. This glassy state is mostly attributed to the frustration induced by magnetic interactions between randomly distributed particles, although the surface spins contribution cannot be discarded. The effective energy barrier distribution obtained from the analysis of the time dependence of the thermoremanence in terms of the T ln (t/tau sub 0) scaling shows a maximum located at energies higher than the mean anisotropy energy barrier. When doing the relaxation experiments after field cooling at increasing fields, the obtained effective energy distribution progressively resembles the anisotropy energy distribution. Therefore, we demonstrate how the glassy state can be erased by applying a magnetic field.

  7. Magnetic particle mixing with magnetic micro-convection for microfluidics

    Energy Technology Data Exchange (ETDEWEB)

    Kitenbergs, Guntars, E-mail: guntars.kitenbergs@lu.lv [MMML Lab, Department of Theoretical Physics, University of Latvia, Zeļļu 8, LV-1002 Riga (Latvia); Sorbonne Universites, UPMC Univ Paris 06, UMR 8234, PHENIX, 4 place Jussieu, F-75005 Paris (France); CNRS, UMR 8234, PHENIX, 4 place Jussieu, F-75005 Paris (France); Erglis, Kaspars, E-mail: kaspars.erglis@lu.lv [MMML Lab, Department of Theoretical Physics, University of Latvia, Zeļļu 8, LV-1002 Riga (Latvia); Perzynski, Régine, E-mail: regine.perzynski@upmc.fr [Sorbonne Universites, UPMC Univ Paris 06, UMR 8234, PHENIX, 4 place Jussieu, F-75005 Paris (France); CNRS, UMR 8234, PHENIX, 4 place Jussieu, F-75005 Paris (France); Cēbers, Andrejs, E-mail: aceb@tok.sal.lv [MMML Lab, Department of Theoretical Physics, University of Latvia, Zeļļu 8, LV-1002 Riga (Latvia)

    2015-04-15

    In this paper we discuss the magnetic micro-convection phenomenon as a tool for mixing enhancement in microfluidics systems in cases when one of the miscible fluids is a magnetic particle colloid. A system of a water-based magnetic fluid and water is investigated experimentally under homogeneous magnetic field in a Hele–Shaw cell. Subsequent image analysis both qualitatively and quantitatively reveals the high enhancement of mixing efficiency provided by this method. The mixing efficiency dependence on the magnetic field and the physical limits is discussed. A suitable model for a continuous-flow microfluidics setup for mixing with magnetic micro-convection is also proposed and justified with an experiment. In addition, possible applications in improving the speed of ferrohydrodynamic sorting and magnetic label or selected tracer mixing in lab on a chip systems are noted. - Highlights: • We study the magnetic micro-convection as a mixing method in microfluidics. • We show that the method enhances mixing with magnetic field squared dependency. • We propose a flow cell setup for mixing and justify it with a sample experiment. • The mixing method can be easily implemented in an existing microfluidics setup.

  8. Argonne lectures on particles accelerator magnets

    Energy Technology Data Exchange (ETDEWEB)

    Devred, A

    1999-09-01

    The quest for elementary particles has promoted the development of particle accelerators producing beams of increasingly higher energies. In a synchrotron, the particle energy is directly proportional to the product of the machine's radius times the bending magnets' field strength. Present proton experiments at the TeV scale require facilities with circumferences ranging from a few to tens of kilometers and relying on a large number (several hundred to several thousand) high field dipole magnets and high field gradient quadrupole magnets. These electro-magnets use high-current-density, low-critical-temperature superconducting cables and are cooled down at liquid helium temperature. They are among the most costly and the most challenging components of the machine. After explaining what are the various types of accelerator magnets and why they are needed (lecture 1), we briefly recall the origins of superconductivity and we review the parameters of existing superconducting particle accelerators (lecture 2). Then, we review the superconducting materials that are available at industrial scale (chiefly, NbTi and Nb{sub 3}Sn) and we explain in details the manufacturing of NbTi wires and cables (lecture 3). We also present the difficulties of processing and insulating Nb{sub 3}Sn conductors, which so far have limited the use of this material in spite of its superior performances. We continue by discussing the two dimensional current distributions which are the most appropriate for generating pure dipole and quadrupole fields and we explain how these ideal distributions can be approximated by so called cos{theta} and cos 2{theta} coil designs (lecture 4). We also present a few alternative designs which are being investigated and we describe the difficulties of realizing coil ends. Next, we present the mechanical design concepts that are used in existing accelerator magnets (lecture 5) and we describe how the magnets are assembled (lecture 6). Some of the toughest

  9. Biodegradable Magnetic Particles for Cellular MRI

    Science.gov (United States)

    Nkansah, Michael Kwasi

    Cell transplantation has the potential to treat numerous diseases and injuries. While magnetic particle-enabled, MRI-based cell tracking has proven useful for visualizing the location of cell transplants in vivo, current formulations of particles are either too weak to enable single cell detection or have non-degradable polymer matrices that preclude clinical translation. Furthermore, the off-label use of commercial agents like Feridex®, Bangs beads and ferumoxytol for cell tracking significantly stunts progress in the field, rendering it needlessly susceptible to market externalities. The recent phasing out of Feridex from the market, for example, heightens the need for a dedicated agent specifically designed for MRI-based cell tracking. To this end, we engineered clinically viable, biodegradable particles of iron oxide made using poly(lactide-co-glycolide) (PLGA) and demonstrated their utility in two MRI-based cell tracking paradigms in vivo. Both micro- and nanoparticles (2.1±1.1 μm and 105±37 nm in size) were highly magnetic (56.7-83.7 wt% magnetite), and possessed excellent relaxometry (r2* relaxivities as high as 614.1 s-1mM-1 and 659.1 s -1mM-1 at 4.7 T respectively). Magnetic PLGA micropartides enabled the in vivo monitoring of neural progenitor cell migration to the olfactory bulb in rat brains over 2 weeks at 11.7 T with ˜2-fold greater contrast-to-noise ratio and ˜4-fold better sensitivity at detecting migrated cells in the olfactory bulb than Bangs beads. Highly magnetic PLGA nanoparticles enabled MRI detection (at 11.7 T) of up to 10 rat mesenchymal cells transplanted into rat brain at 100-μm resolution. Highly magnetic PLGA particles were also shown to degrade by 80% in mice liver over 12 weeks in vivo. Moreover, no adverse effects were observed on cellular viability and function in vitro after labeling a wide range of cells. Magnetically labeled rat mesenchymal and neural stem cells retained their ability to differentiate into multiple

  10. Homogeneous Biosensing Based on Magnetic Particle Labels

    KAUST Repository

    Schrittwieser, Stefan

    2016-06-06

    The growing availability of biomarker panels for molecular diagnostics is leading to an increasing need for fast and sensitive biosensing technologies that are applicable to point-of-care testing. In that regard, homogeneous measurement principles are especially relevant as they usually do not require extensive sample preparation procedures, thus reducing the total analysis time and maximizing ease-of-use. In this review, we focus on homogeneous biosensors for the in vitro detection of biomarkers. Within this broad range of biosensors, we concentrate on methods that apply magnetic particle labels. The advantage of such methods lies in the added possibility to manipulate the particle labels by applied magnetic fields, which can be exploited, for example, to decrease incubation times or to enhance the signal-to-noise-ratio of the measurement signal by applying frequency-selective detection. In our review, we discriminate the corresponding methods based on the nature of the acquired measurement signal, which can either be based on magnetic or optical detection. The underlying measurement principles of the different techniques are discussed, and biosensing examples for all techniques are reported, thereby demonstrating the broad applicability of homogeneous in vitro biosensing based on magnetic particle label actuation.

  11. On the Possible Trajectories of Particles with Spin. II. Particles in the Stationary Homogeneous Magnetic Field

    CERN Document Server

    Tarakanov, Alexander N

    2016-01-01

    The behavior of spinning particles in the stationary homogeneous magnetic field is considered and all types of trajectories for massive and massless particles are found. It is shown that spin of particles in a magnetic field is always arranged parallel or antiparallel to the field. Helicity $e$ plays a role of electric charge. The oscillation frequency of massless particle in a magnetic field increases.

  12. Magnetic particle imaging of blood coagulation

    Energy Technology Data Exchange (ETDEWEB)

    Murase, Kenya, E-mail: murase@sahs.med.osaka-u.ac.jp; Song, Ruixiao; Hiratsuka, Samu [Department of Medical Physics and Engineering, Division of Medical Technology and Science, Faculty of Health Science, Graduate School of Medicine, Osaka University, Osaka 565-0871 (Japan)

    2014-06-23

    We investigated the feasibility of visualizing blood coagulation using a system for magnetic particle imaging (MPI). A magnetic field-free line is generated using two opposing neodymium magnets and transverse images are reconstructed from the third-harmonic signals received by a gradiometer coil, using the maximum likelihood-expectation maximization algorithm. Our MPI system was used to image the blood coagulation induced by adding CaCl{sub 2} to whole sheep blood mixed with magnetic nanoparticles (MNPs). The “MPI value” was defined as the pixel value of the transverse image reconstructed from the third-harmonic signals. MPI values were significantly smaller for coagulated blood samples than those without coagulation. We confirmed the rationale of these results by calculating the third-harmonic signals for the measured viscosities of samples, with an assumption that the magnetization and particle size distribution of MNPs obey the Langevin equation and log-normal distribution, respectively. We concluded that MPI can be useful for visualizing blood coagulation.

  13. Magnetic particle imaging of blood coagulation

    Science.gov (United States)

    Murase, Kenya; Song, Ruixiao; Hiratsuka, Samu

    2014-06-01

    We investigated the feasibility of visualizing blood coagulation using a system for magnetic particle imaging (MPI). A magnetic field-free line is generated using two opposing neodymium magnets and transverse images are reconstructed from the third-harmonic signals received by a gradiometer coil, using the maximum likelihood-expectation maximization algorithm. Our MPI system was used to image the blood coagulation induced by adding CaCl2 to whole sheep blood mixed with magnetic nanoparticles (MNPs). The "MPI value" was defined as the pixel value of the transverse image reconstructed from the third-harmonic signals. MPI values were significantly smaller for coagulated blood samples than those without coagulation. We confirmed the rationale of these results by calculating the third-harmonic signals for the measured viscosities of samples, with an assumption that the magnetization and particle size distribution of MNPs obey the Langevin equation and log-normal distribution, respectively. We concluded that MPI can be useful for visualizing blood coagulation.

  14. Magnetic interaction of Janus magnetic particles suspended in a viscous fluid.

    Science.gov (United States)

    Seong, Yujin; Kang, Tae Gon; Hulsen, Martien A; den Toonder, Jaap M J; Anderson, Patrick D

    2016-02-01

    We studied the magnetic interaction between circular Janus magnetic particles suspended in a Newtonian fluid under the influence of an externally applied uniform magnetic field. The particles are equally compartmentalized into paramagnetic and nonmagnetic sides. A direct numerical scheme is employed to solve the magnetic particulate flow in the Stokes flow regime. Upon applying the magnetic field, contrary to isotropic paramagnetic particles, a single Janus particle can rotate due to the magnetic torque created by the magnetic anisotropy of the particle. In a two-particle problem, the orientation of each particle is found to be an additional factor that affects the critical angle separating the nature of magnetic interaction. Using multiparticle problems, we show that the orientation of the particles has a significant influence on the dynamics of the particles, the fluid flow induced by the actuated particles, and the final conformation of the particles. Straight and staggered chain structures observed experimentally can be reproduced numerically in a multiple particle problem.

  15. Particle Demagnetization in Collisionless Magnetic Reconnection

    Science.gov (United States)

    Hesse, Michael

    2006-01-01

    The dissipation mechanism of magnetic reconnection remains a subject of intense scientific interest. On one hand, one set of recent studies have shown that particle inertia-based processes, which include thermal and bulk inertial effects, provide the reconnection electric field in the diffusion region. In this presentation, we present analytical theory results, as well as 2.5 and three-dimensional PIC simulations of guide field magnetic reconnection. We will show that diffusion region scale sizes in moderate and large guide field cases are determined by electron Larmor radii, and that analytical estimates of diffusion region dimensions need to include description of the heat flux tensor. The dominant electron dissipation process appears to be based on thermal electron inertia, expressed through nongyrotropic electron pressure tensors. We will argue that this process remains viable in three dimensions by means of a detailed comparison of high resolution particle-in-cell simulations.

  16. Magnetic Properties of Nanometer-sized Crystalline and Amorphous Particles

    DEFF Research Database (Denmark)

    Mørup, Steen; Bødker, Franz; Hansen, Mikkel Fougt;

    1997-01-01

    Amorphous transition metal-metalloid alloy particles can be prepared by chemical preparation techniques. We discuss the preparation of transition metal-boron and iron-carbon particles and their magnetic properties. Nanometer-sized particles of both crystalline and amorphous magnetic materials...... are superparamagnetic at finite temperatures. The temperature dependence of the superparamagnetic relaxation time and the influence of inter-particle interactions is discussed. Finally, some examples of studies of surface magnetization of alpha-Fe particles are presented....

  17. Magnetic Properties of Nanometer-sized Crystalline and Amorphous Particles

    DEFF Research Database (Denmark)

    Mørup, Steen; Bødker, Franz; Hansen, Mikkel Fougt

    1997-01-01

    Amorphous transition metal-metalloid alloy particles can be prepared by chemical preparation techniques. We discuss the preparation of transition metal-boron and iron-carbon particles and their magnetic properties. Nanometer-sized particles of both crystalline and amorphous magnetic materials...... are superparamagnetic at finite temperatures. The temperature dependence of the superparamagnetic relaxation time and the influence of inter-particle interactions is discussed. Finally, some examples of studies of surface magnetization of alpha-Fe particles are presented....

  18. Magnetic Particle Testing, RQA/M1-5330.16.

    Science.gov (United States)

    National Aeronautics and Space Administration, Huntsville, AL. George C. Marshall Space Flight Center.

    As one in the series of classroom training handbooks, prepared by the U.S. space program, instructional material is presented in this volume concerning familiarization and orientation on magnetic particle testing. The subject is divided under the following headings: Introduction, Principles of Magnetic Particle Testing, Magnetic Particle Test…

  19. Computational Simulations of Magnetic Particle Capture in Arterial Flows

    NARCIS (Netherlands)

    Haverkort, J.W.; Kenjeres, S.; Kleijn, C.R.

    2009-01-01

    The aim of Magnetic Drug Targeting (MDT) is to concentrate drugs, attached to magnetic particles, in a specific part of the human body by applying a magnetic field. Computational simulations are performed of blood flow and magnetic particle motion in a left coronary artery and a carotid artery, usin

  20. Tracer design for magnetic particle imaging (invited).

    Science.gov (United States)

    Ferguson, R Matthew; Khandhar, Amit P; Krishnan, Kannan M

    2012-04-01

    Magnetic particle imaging (MPI) uses safe iron oxide nanoparticle tracers to offer fundamentally new capabilities for medical imaging, in applications as vascular imaging and ultra-sensitive cancer therapeutics. MPI is perhaps the first medical imaging platform to intrinsically exploit nanoscale material properties. MPI tracers contain magnetic nanoparticles whose tunable, size-dependent magnetic properties can be optimized by selecting a particular particle size and narrow size-distribution. In this paper we present experimental MPI measurements acquired using a homemade MPI magnetometer: a zero-dimensional MPI imaging system designed to characterize tracer performance by measuring the derivative of the time-varying tracer magnetization, M'(H(t)), at a driving frequency of 25 kHz. We show that MPI performance is optimized by selecting phase-pure magnetite tracers of a particular size and narrow size distribution; in this work, tracers with 20 nm median diameter, log-normal distribution shape parameter, σ(v), equal to 0.26, and hydrodynamic diameter equal to 30 nm showed the best performance. Furthermore, these optimized MPI tracers show 4 × greater signal intensity (measured at the third harmonic) and 20% better spatial resolution compared with commercial nanoparticles developed for MRI.

  1. Torsion profiling of proteins using magnetic particles.

    Science.gov (United States)

    van Reenen, A; Gutiérrez-Mejía, F; van IJzendoorn, L J; Prins, M W J

    2013-03-05

    We report a method to profile the torsional spring properties of proteins as a function of the angle of rotation. The torque is applied by superparamagnetic particles and has been calibrated while taking account of the magnetization dynamics of the particles. We record and compare the torsional profiles of single Protein G-Immunoglobulin G (IgG) and IgG-IgG complexes, sandwiched between a substrate and a superparamagnetic particle, for torques in the range between 0.5 × 10(3) and 5 × 10(3) pN·nm. Both molecular systems show torsional stiffening for increasing rotation angle, but the elastic and inelastic torsion stiffnesses are remarkably different. We interpret the results in terms of the structural properties of the molecules. The torsion profiling technique opens new dimensions for research on biomolecular characterization and for research on bio-nanomechanical structure-function relationships.

  2. Test particles in a magnetized conformastatic spacetime

    CERN Document Server

    Gutiérrez-Piñeres, Antonio C; Quevedo, Hernando

    2016-01-01

    A class of exact conformastatic solutions of the Einstein-Maxwell field equations is presented in which the gravitational and electromagnetic potentials are completely determined by a harmonic function. We derive the equations of motion for neutral and charged particles in a spacetime background characterized by this class of solutions. As an example, we focus on the analysis of a particular harmonic function which generates a singularity-free and asymptotically flat spacetime and, therefore, describes the gravitational field of a punctual mass endowed with a magnetic field. In this particular case, we investigate the main physical properties of equatorial circular orbits. We show that due to the electromagnetic interaction, it is possible to have charged test particles which stay at rest with respect to a static observer located at infinity. Additionally, we obtain an analytic expression for the perihelion advance of test particles. Our theoretical predictions are compared with the observational data calibra...

  3. EDITORIAL: Cluster issue on fine particle magnetism

    Science.gov (United States)

    Fiorani, D.

    2008-07-01

    This Cluster issue of Journal of Physics D: Applied Physics arises from the 6th International Conference on Fine Particle Magnetism (ICFPM) held in Rome during 9-12 October 2007 at the headquarters of the National Research Council (NCR). It contains a collection of papers based on both invited and contributed presentations at the meeting. The ICFPM Conferences have previously been held in Rome, Italy (1991), Bangor, UK (1996), Barcelona, Spain (1999), Pittsburgh, USA (2002) and London, UK (2004). The aim of this series of Conferences is to bring together the experts in the field of nanoparticle magnetism at a single forum to discuss recent developments in both theoretical and experimental aspects, and technological applications. The Conference programme included sessions on: new materials, novel synthesis and processing techniques, with special emphasis on self-organized magnetic arrays; theory and modelling; surface and interface properties; transport properties; spin dynamics; magnetization reversal mechanisms; magnetic recording media and permanent magnets; biomedical applications and advanced investigation techniques. I would like to thank the European Physical Society and the Innovative Magnetic and Superconducting Materials and Devices Project of the Materials and Devices Department and the Institute of Structure of Matter (ISM) of CNR for their support. Thanks are also due to the members of the Programme Committee, to the local Organizing Committee, chaired by Elisabetta Agostinelli and to all the Conference participants. I am also indebted to the many scientists who contributed to assuring the high-quality of this Cluster by donating their time to reviewing the manuscripts contained herein. Finally, I'd like to dedicate this issue to the memories of Jean Louis Dormann, a great expert in nanoparticle magnetism, who was one of the promoters and first organizers of this series of Conferences, and of Grazia Ianni, the Conference secretary, who died before her

  4. Particle flocculation and filtration by high-gradient magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Tsouris, C. [Oak Ridge National Lab., TN (United States); Yiacoumi, S. [Georgie Inst. of Technology, Atlanta, GA (United States)

    1997-01-01

    Flocculation and filtration of micrometer-sized particles in a high-gradient magnetic field (HGMF) were investigated. Experiments were conducted using a cryogenic magnet of 6 Tesla maximum strength. Hematite particles were used for flocculation and filtration experiments. A new approach of using magnetic fields to enhance separation of weakly magnetic particles was also investigated. This approach is based on magnetic seeding which involves flocculation of existing non-magnetic particles with injected paramagnetic particles. A particle-flocculation model was developed based on trajectory analysis. External forces due to gravity and magnetism, and interparticle forces such as electrostatic, hydrodynamic, magnetic dipole, and van der Waals forces, were taken into consideration in these models.

  5. Associated Particle Tagging (APT) in Magnetic Spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, David V.; Baciak, James E.; Stave, Sean C.; Chichester, David; Dale, Daniel; Kim, Yujong; Harmon, Frank

    2012-10-16

    Summary In Brief The Associated Particle Tagging (APT) project, a collaboration of Pacific Northwest National Laboratory (PNNL), Idaho National Laboratory (INL) and the Idaho State University (ISU)/Idaho Accelerator Center (IAC), has completed an exploratory study to assess the role of magnetic spectrometers as the linchpin technology in next-generation tagged-neutron and tagged-photon active interrogation (AI). The computational study considered two principle concepts: (1) the application of a solenoidal alpha-particle spectrometer to a next-generation, large-emittance neutron generator for use in the associated particle imaging technique, and (2) the application of tagged photon beams to the detection of fissile material via active interrogation. In both cases, a magnetic spectrometer momentum-analyzes charged particles (in the neutron case, alpha particles accompanying neutron generation in the D-T reaction; in the tagged photon case, post-bremsstrahlung electrons) to define kinematic properties of the relevant neutral interrogation probe particle (i.e. neutron or photon). The main conclusions of the study can be briefly summarized as follows: Neutron generator: • For the solenoidal spectrometer concept, magnetic field strengths of order 1 Tesla or greater are required to keep the transverse size of the spectrometer smaller than 1 meter. The notional magnetic spectrometer design evaluated in this feasibility study uses a 5-T magnetic field and a borehole radius of 18 cm. • The design shows a potential for 4.5 Sr tagged neutron solid angle, a factor of 4.5 larger than achievable with current API neutron-generator designs. • The potential angular resolution for such a tagged neutron beam can be less than 0.5o for modest Si-detector position resolution (3 mm). Further improvement in angular resolution can be made by using Si-detectors with better position resolution. • The report documents several features of a notional generator design incorporating the

  6. 2008 LHC Open Days LHC magnets on display

    CERN Multimedia

    2008-01-01

    Over the last few years you’ve probably seen many of the 15 m long blue LHC dipole magnets being ferried around the site. Most of them are underground now, but on the LHC Open Days on 5 and 6 April the magnets will also play a central role on the surface. Installation of one of the LHC dipole magnets on the Saint-Genis roundabout on 7 March. The LHC dipole testing facility with several magnets at various stages of testing. The 27 km ring of the LHC consists of 1232 double-aperture superconducting dipole magnets, 360 short straight sections (SSS) and 114 special SSS for the insertion regions. On the Open Day, you will be able to "Follow the LHC magnets" through different stages around the site, culminating in their descent into the tunnel. Discover all the many components that have to be precisely integrated in the magnet casings, and talk to the engine...

  7. Test particles in a magnetized conformastatic spacetime

    Science.gov (United States)

    Gutiérrez-Piñeres, Antonio C.; Capistrano, Abraão J. S.; Quevedo, Hernando

    2016-06-01

    A class of exact conformastatic solutions of the Einstein-Maxwell field equations is presented in which the gravitational and electromagnetic potentials are completely determined by a harmonic function. We derive the equations of motion for neutral and charged particles in a spacetime background characterized by this class of solutions. As an example, we focus on the analysis of a particular harmonic function, which generates a singularity-free and asymptotically flat spacetime that describes the gravitational field of a punctual mass endowed with a magnetic field. In this particular case, we investigate the main physical properties of equatorial circular orbits. We show that due to the electromagnetic interaction, it is possible to have charged test particles which stay at rest with respect to a static observer located at infinity. Additionally, we obtain an analytic expression for the perihelion advance of test particles and the corresponding explicit value in the case of a punctual magnetic mass. We show that the analytical expressions obtained from our analysis are sufficient for being confronted with observations in order to establish whether such objects can exist in nature.

  8. Use of bacteriophage particles displaying influenza virus hemagglutinin for the detection of hemagglutination-inhibition antibodies.

    Science.gov (United States)

    Domm, William; Brewer, Matthew; Baker, Steven F; Feng, Changyong; Martínez-Sobrido, Luis; Treanor, John; Dewhurst, Stephen

    2014-03-01

    Bacteriophage lambda capsids provide a flexible molecular scaffold that can be engineered to display a wide range of exogenous proteins, including full-length viral glycoproteins produced in eukaryotic cells. One application for such particles lies in the detection of virus-specific antibodies, since they may obviate the need to work with infectious stocks of highly pathogenic or emerging viruses that can pose significant biosafety and biocontainment challenges. Bacteriophage lambda capsids were produced that displayed an insect-cell derived, recombinant H5 influenza virus hemagglutinin (HA) on their surface. The particles agglutinated red blood cells efficiently, in a manner that could be blocked using H5 HA-specific monoclonal antibodies. The particles were then used to develop a modified hemagglutinination-inhibition (HAI) assay, which successfully identified human sera with H5 HA-specific HAI activity. These results demonstrate the utility of HA-displaying bacteriophage capsids for the detection of influenza virus-specific HAI antibodies.

  9. Particle parameter analyzing system. [x-y plotter circuits and display

    Science.gov (United States)

    Hansen, D. O.; Roy, N. L. (Inventor)

    1969-01-01

    An X-Y plotter circuit apparatus is described which displays an input pulse representing particle parameter information, that would ordinarily appear on the screen of an oscilloscope as a rectangular pulse, as a single dot positioned on the screen where the upper right hand corner of the input pulse would have appeared. If another event occurs, and it is desired to display this event, the apparatus is provided to replace the dot with a short horizontal line.

  10. Acceleration of superparamagnetic particles with magnetic fields

    Science.gov (United States)

    Stange, R.; Lenk, F.; Bley, T.; Boschke, E.

    2017-04-01

    High magnetic capture efficiency in the context of Biomagnetic Separation (BMS) using superparamagnetic particles (SMPs) requires efficient mixing and high relative velocities between cellular and other targets and SMPs. For this purpose, batch processes or microfluidic systems are commonly used. Here, we analyze the characteristics of an in-house developed batch process experimental setup, the Electromagnetic Sample Mixer (ESM) described earlier. This device uses three electromagnets to increase the relative velocity between SMPs and targets. We carry out simulations of the magnetic field in the ESM and in a simpler paradigmatic setup, and thus were able to calculate the force field acting on the SMPs and to simulate their relative velocities and fluid dynamics due to SMP movement. In this way we were able to show that alternate charging of the magnets induces a double circular stream of SMPs in the ESM, resulting in high relative velocities of SMPs to the targets. Consequently, due to the conservation of momentum, the fluid experiences an acceleration induced by the SMPs. We validated our simulations by microscopic observation of the SMPs in the magnetic field, using a homemade apparatus designed to accommodate a long working-distance lens. By comparing the results of modeling this paradigmatic setup with the experimental observations, we determined that the velocities of the SMPs corresponded to the results of our simulations.

  11. A magnetic particle micro-trap for large trapping surfaces

    KAUST Repository

    Gooneratne, Chinthaka P.

    2012-01-08

    Manipulation of micron-size magnetic particles of the superparamagnetic type contributes significantly in many applications like controlling the antibody/antigen binding process in immunoassays. Specifically, more target biomolecules can be attached/tagged and analyzed since the three dimensional structure of the magnetic particles increases the surface to volume ratio. Additionally, such biomolecular-tagged magnetic particles can be easily manipulated by an external magnetic field due to their superparamagnetic behavior. Therefore, magnetic particle- based immunoassays are extensively applied in micro-flow cytometry. The design of a square-loop micro-trap as a magnetic particle manipulator as well as numerical and experimental analysis is presented. Experimental results showed that the micro-trap could successfully trap and concentrate magnetic particles from a large to a small area with a high spatial range.

  12. Magnetic poly(lactide-co-glycolide) (PLGA) and cellulose particles for MRI-based cell tracking

    Science.gov (United States)

    Nkansah, Michael K.; Thakral, Durga; Shapiro, Erik M.

    2010-01-01

    Biodegradable, superparamagnetic micro- and nanoparticles of poly(lactide-co-glycolide) (PLGA) and cellulose were designed, fabricated and characterized for magnetic cell labeling. Monodisperse nanocrystals of magnetite were incorporated into micro- and nanoparticles of PLGA and cellulose with high efficiency using an oil-in-water single emulsion technique. Superparamagnetic cores had high magnetization (72.1 emu/g). The resulting polymeric particles had smooth surface morphology and high magnetite content (43.3 wt% for PLGA and 69.6 wt% for cellulose). While PLGA and cellulose nanoparticles displayed highest r2* values per millimole of iron (399 s-1mM-1 for cellulose and 505 s-1mM-1 for PLGA), micron-sized PLGA particles had a much higher r2* per particle than either. After incubation for a month in citrate buffer (pH 5.5), magnetic PLGA particles lost close to 50% of their initial r2* molar relaxivity, while magnetic cellulose particles remained intact, preserving over 85% of their initial r2* molar relaxivity. Lastly, mesenchymal stem cells and human breast adenocarcinoma cells were magnetically labeled using these particles with no detectable cytotoxicity. These particles are ideally suited for non-invasive cell tracking in vivo via MRI and due to their vastly different degradation properties, offer unique potential for dedicated use for either short (PLGA-based particles) or long term (cellulose-based particles) experiments. PMID:21404328

  13. Magnetic poly(lactide-co-glycolide) and cellulose particles for MRI-based cell tracking.

    Science.gov (United States)

    Nkansah, Michael K; Thakral, Durga; Shapiro, Erik M

    2011-06-01

    Biodegradable, superparamagnetic microparticles and nanoparticles of poly(lactide-co-glycolide) (PLGA) and cellulose were designed, fabricated, and characterized for magnetic cell labeling. Monodisperse nanocrystals of magnetite were incorporated into microparticles and nanoparticles of PLGA and cellulose with high efficiency using an oil-in-water single emulsion technique. Superparamagnetic cores had high magnetization (72.1 emu/g). The resulting polymeric particles had smooth surface morphology and high magnetite content (43.3 wt % for PLGA and 69.6 wt % for cellulose). While PLGA and cellulose nanoparticles displayed highest r 2* values per millimole of iron (399 sec(-1) mM(-1) for cellulose and 505 sec(-1) mM(-1) for PLGA), micron-sized PLGA particles had a much higher r 2* per particle than either. After incubation for a month in citrate buffer (pH 5.5), magnetic PLGA particles lost close to 50% of their initial r 2* molar relaxivity, while magnetic cellulose particles remained intact, preserving over 85% of their initial r 2* molar relaxivity. Lastly, mesenchymal stem cells and human breast adenocarcinoma cells were magnetically labeled using these particles with no detectable cytotoxicity. These particles are ideally suited for noninvasive cell tracking in vivo via MRI and due to their vastly different degradation properties, offer unique potential for dedicated use for either short (PLGA-based particles) or long-term (cellulose-based particles) experiments.

  14. Hysteresis effects in the cores of particle accelerator magnets

    CERN Document Server

    AUTHOR|(CDS)2086181; Schoerling, Daniel

    A study of the hysteresis effects in the cores of particle accelerator magnets has been performed in the framework of the work presented in this thesis. This study has been focused on normal conducting particle accelerator magnets whose cores are manufactured using ferromagnetic materials. The magnetic circuits have been modelled using the developed models: one model for the magnetic circuit and one for the magnetization of the material in the core. The parameters of the magnetic circuit model have been identified with the help of simulations which rely on the finite element method (Opera 3D), while the parameters of the magnetic hysteresis model have been identified through experimental measurements performed using a method developed in the framework of this work. The modelling results have been validated by means of experimental measurements performed on two magnets: one small size magnet which has been specifically designed and manufactured, and one magnet which is currently used in a particle accelerator ...

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

    Institute of Scientific and Technical Information of China (English)

    Zhiya; Ma; Huizhou; Liu

    2007-01-01

    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.

  16. Charged-particle orbits near a magnetic null point

    OpenAIRE

    Jaroensutasinee, K.; Rowlands, G.

    2000-01-01

    An approximate analytical expression is obtained for the orbits of a charged particle moving in a cusp magnetic field. The particle orbits pass close to or through a region of zero magnetic field before being reflected in regions where the magnetic field is strong. Comparison with numerically evaluated orbits shows that the analytical formula is surprisingly good and captures all the main features of the particle motion. A map describing the long-time behaviour of such orbits is obtained.

  17. Remote Control of T Cell Activation Using Magnetic Janus Particles.

    Science.gov (United States)

    Lee, Kwahun; Yi, Yi; Yu, Yan

    2016-06-20

    We report a strategy for using magnetic Janus microparticles to control the stimulation of T cell signaling with single-cell precision. To achieve this, we designed Janus particles that are magnetically responsive on one hemisphere and stimulatory to T cells on the other side. By manipulating the rotation and locomotion of Janus particles under an external magnetic field, we could control the orientation of the particle-cell recognition and thereby the initiation of T cell activation. This study demonstrates a step towards employing anisotropic material properties of Janus particles to control single-cell activities without the need of complex magnetic manipulation devices.

  18. Microwave characteristics of low density flaky magnetic particles

    Energy Technology Data Exchange (ETDEWEB)

    Wenqiang, Zhang, E-mail: zwqzwqzwqzwq@126.com [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China); College of Engineering, China Agricultural University, Beijing 100083 (China); Deyuan, Zhang [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China); Jun, Cai, E-mail: jun_cai@buaa.edu.cn [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China)

    2013-04-15

    Diatomite coated with thin Fe films were obtained by the Chemical Vapor Deposition process. The resultant Fe-coated flaky diatomite particles had low densities (2.7–4.0 g/cm{sup 3}) and high saturation magnetization (93–157 emu/g). Annealing treatment led to grain growth and an increased saturation magnetization. The high frequency properties of the composites consisting of Fe-coated flaky diatomite particles and wax were investigated. The permittivity and permeability increased with increasing flaky magnetic particles content in the composite and increasing the Fe weight percentage of the particles. The reflection loss of the composite was found dependent on the absorber material thickness, wax:flaky magnetic particles ratios, the Fe content, as well as the annealing treatment. At a thickness of 1 mm, the composite records a minimum reflection loss of −18 dB at 6 GHz. - Highlights: ► We synthesize the flaky magnetic particles with the diatomite as template. ► The flaky magnetic particles coating layers are constituted by α-Fe. ► The flaky magnetic particles have good static magnetic properties. ► The flaky magnetic particles are a kind light weight high performance microwave absorber.

  19. Fluorescent-magnetic Janus particles prepared via seed emulsion polymerization.

    Science.gov (United States)

    Kaewsaneha, Chariya; Bitar, Ahmad; Tangboriboonrat, Pramuan; Polpanich, Duangporn; Elaissari, Abdelhamid

    2014-06-15

    Anisotropic polymeric colloidal or Janus particles possessing simultaneous magnetic and fluorescent properties were successfully prepared via the swelling-diffusion or the in situ emulsion polymerization method. In the swelling-diffusion process, magnetic emulsions (an organic ferrofluid dispersed in aqueous medium) were synthesized and used for seeds of submicron magnetic Janus particles. After swelling the anisotropic particles obtained by 1-pyrene-carboxaldehyde fluorescent dye dissolved in tetrahydrofuran, well-defined fluorescent-magnetic Janus particles were produced. In the in situ emulsion polymerization, styrene monomer mixed with fluorescent dye monomers, i.e., 1-pyrenylmethyl methacrylate (PyMMA) or fluorescein dimethacrylate (FDMA), and an oil-soluble initiator (2,2'-azobis(2-isobutyronitrile)) were emulsified in the presence of magnetic seed emulsions. The confocal microscopic images showed the fluorescent-magnetic Janus particles with high fluorescent intensity when a fluorescent crosslinker monomer FDMA was employed.

  20. Projection x-space magnetic particle imaging.

    Science.gov (United States)

    Goodwill, Patrick W; Konkle, Justin J; Zheng, Bo; Saritas, Emine U; Conolly, Steven M

    2012-05-01

    Projection magnetic particle imaging (MPI) can improve imaging speed by over 100-fold over traditional 3-D MPI. In this work, we derive the 2-D x-space signal equation, 2-D image equation, and introduce the concept of signal fading and resolution loss for a projection MPI imager. We then describe the design and construction of an x-space projection MPI scanner with a field gradient of 2.35 T/m across a 10 cm magnet free bore. The system has an expected resolution of 3.5 × 8.0 mm using Resovist tracer, and an experimental resolution of 3.8 × 8.4 mm resolution. The system images 2.5 cm × 5.0 cm partial field-of views (FOVs) at 10 frames/s, and acquires a full field-of-view of 10 cm × 5.0 cm in 4 s. We conclude by imaging a resolution phantom, a complex "Cal" phantom, mice injected with Resovist tracer, and experimentally confirm the theoretically predicted x-space spatial resolution.

  1. Improved properties of magnetic particles by combination of different polymer materials as particle matrix

    Energy Technology Data Exchange (ETDEWEB)

    Gruettner, Cordula E-mail: info@micromod.de; Rudershausen, Sandra; Teller, Joachim

    2001-07-01

    The properties of individual types of magnetic particles were improved by combining different polymer matrix materials. The hybrids of magnetic polysaccharide-polystyrene, silica-polystyrene, silica-polysaccharide, polysaccharide-poly(alkylcyanoacrylate) and polysaccharide-poly(lactic acid) particles are discussed and characterized by electrokinetic measurements and studies of their protein binding capacity. The improved properties of these magnetic particles lead to novel applications in diagnostics, molecular biology and biomedicine.

  2. Torsion stiffness of a protein pair determined by magnetic particles

    NARCIS (Netherlands)

    Janssen, X.J.A.; Van Noorloos, J.M.; Jacob, A.; Van IJzendoorn, L.J.; De Jong, A.M.; Prins, M.W.J.

    2012-01-01

    We demonstrate the ability to measure torsion stiffness of a proteincomplex by applying a controlled torque on a magnetic particle. Asa model system we use protein G bound to an IgG antibody. The protein pair is held between a magnetic particle and a polystyrene substrate. The angular orientation of

  3. Dendrimer-coated magnetic particles for radionuclide separation

    NARCIS (Netherlands)

    Grüttner, Cordula; Böhmer, Volker; Casnati, Alessandro; Dozol, Jean-Francois; Reinhoudt, David; Reinoso garcia, M.M.; Rudershausen, Sandra; Teller, Joachim; Ungaro, Rocco; Verboom, Willem; Wang, Pingshan

    2005-01-01

    Magnetic particles were synthesised for radionuclide removal from nuclear wastes by magnetic separation. Dendrimers with terminal amino groups attached to the particle surface were used to bind chelating groups for lanthanides and actinides. This led to a 50–400-fold increase of the distribution

  4. Switching Behaviour of Magnetic Particles with Dipolar Interaction

    Institute of Scientific and Technical Information of China (English)

    XU Chen; HUI Pak-Ming; CHOW Chow-Wang; LI Zhen-Ya

    2005-01-01

    We study the switching in the magnetic moments of interacting magnetic particles. The dynamics of the magneticmoments is governed by a coupled set of Landau-Lifshitz-Gilbert equations. The magnetic particles are assumed to be spherical in shape, single domain, and have uniaxial anisotropy. Effects of dipolar interaction between the particles, anisotropy energy, an applied switching field with finite spatial extent and a small bias field are considered. When the separation between the particles is small, the dipolar field is significant and it affects the reversal of the magnetic moments. The final configuration attained depends sensitively on the decaying length of the switching field, the inter-particle separation, and the initial configuration. A bias field tends to suppress the effects of a spatially decaying switching field and dipolar interaction between neighbouring particles.

  5. Properties of baculovirus particles displaying GFP analyzed by fluorescence correlation spectroscopy.

    Science.gov (United States)

    Toivola, Jouni; Ojala, Kirsi; Michel, Patrik O; Vuento, Matti; Oker-Blom, Christian

    2002-12-01

    Recombinant baculovirus particles displaying green fluorescent protein (GFP) fused to the major envelope glycoprotein gp64 of the Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) were characterized by fluorescence correlation spectroscopy (FCS). FCS detected Brownian motion of single, intact recombinant baculovirus display particles with a diffusion coefficient (D) of (2.89 +/- 0.74) x 10(-8) cm2s(-1) and an apparent hydrodynamic radius of 83.35 +/- 21.22 nm. In the presence of sodium dodecyl sulfate (SDS), Triton X-100, and octylglucoside, the diffusion time was reduced to the 0.2 ms range (D = 7.57 x 10(-7) cm2s(-1)), showing that the fusion proteins were anchored in the viral envelope. This allowed for a calculation of the number of single gp64 fusion proteins incorporated in the viral membrane. A mean value of 3.2 fluorescent proteins per virus particle was obtained. Our results show that FCS is the method of choice for studying enveloped viruses such as a display virus with one component being GFP.

  6. Full particle orbit effects in regular and stochastic magnetic fields

    Science.gov (United States)

    Ogawa, Shun; Cambon, Benjamin; Leoncini, Xavier; Vittot, Michel; del Castillo-Negrete, Diego; Dif-Pradalier, Guilhem; Garbet, Xavier

    2016-07-01

    We present a numerical study of charged particle motion in a time-independent magnetic field in cylindrical geometry. The magnetic field model consists of an unperturbed reversed-shear (non-monotonic q-profile) helical part and a perturbation consisting of a superposition of modes. Contrary to most of the previous studies, the particle trajectories are computed by directly solving the full Lorentz force equations of motion in a six-dimensional phase space using a sixth-order, implicit, symplectic Gauss-Legendre method. The level of stochasticity in the particle orbits is diagnosed using averaged, effective Poincare sections. It is shown that when only one mode is present, the particle orbits can be stochastic even though the magnetic field line orbits are not stochastic (i.e., fully integrable). The lack of integrability of the particle orbits in this case is related to separatrix crossing and the breakdown of the global conservation of the magnetic moment. Some perturbation consisting of two modes creates resonance overlapping, leading to Hamiltonian chaos in magnetic field lines. Then, the particle orbits exhibit a nontrivial dynamics depending on their energy and pitch angle. It is shown that the regions where the particle motion is stochastic decrease as the energy increases. The non-monotonicity of the q-profile implies the existence of magnetic ITBs (internal transport barriers) which correspond to shearless flux surfaces located in the vicinity of the q-profile minimum. It is shown that depending on the energy, these magnetic ITBs might or might not confine particles. That is, magnetic ITBs act as an energy-dependent particle confinement filter. Magnetic field lines in reversed-shear configurations exhibit topological bifurcations (from homoclinic to heteroclinic) due to separatrix reconnection. We show that a similar but more complex scenario appears in the case of particle orbits that depend in a non-trivial way on the energy and pitch angle of the

  7. Full particle orbit effects in regular and stochastic magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Shun, E-mail: shun.ogawa@cpt.univ-mrs.fr [Aix Marseille Univ., Univ. Toulon, CNRS, CPT, Marseille (France); CEA, IRFM, F-13108 St. Paul-lez-Durance Cedex (France); Cambon, Benjamin; Leoncini, Xavier; Vittot, Michel [Aix Marseille Univ., Univ. Toulon, CNRS, CPT, Marseille (France); Castillo-Negrete, Diego del [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6169 (United States); Dif-Pradalier, Guilhem; Garbet, Xavier [CEA, IRFM, F-13108 St. Paul-lez-Durance Cedex (France)

    2016-07-15

    We present a numerical study of charged particle motion in a time-independent magnetic field in cylindrical geometry. The magnetic field model consists of an unperturbed reversed-shear (non-monotonic q-profile) helical part and a perturbation consisting of a superposition of modes. Contrary to most of the previous studies, the particle trajectories are computed by directly solving the full Lorentz force equations of motion in a six-dimensional phase space using a sixth-order, implicit, symplectic Gauss-Legendre method. The level of stochasticity in the particle orbits is diagnosed using averaged, effective Poincare sections. It is shown that when only one mode is present, the particle orbits can be stochastic even though the magnetic field line orbits are not stochastic (i.e., fully integrable). The lack of integrability of the particle orbits in this case is related to separatrix crossing and the breakdown of the global conservation of the magnetic moment. Some perturbation consisting of two modes creates resonance overlapping, leading to Hamiltonian chaos in magnetic field lines. Then, the particle orbits exhibit a nontrivial dynamics depending on their energy and pitch angle. It is shown that the regions where the particle motion is stochastic decrease as the energy increases. The non-monotonicity of the q-profile implies the existence of magnetic ITBs (internal transport barriers) which correspond to shearless flux surfaces located in the vicinity of the q-profile minimum. It is shown that depending on the energy, these magnetic ITBs might or might not confine particles. That is, magnetic ITBs act as an energy-dependent particle confinement filter. Magnetic field lines in reversed-shear configurations exhibit topological bifurcations (from homoclinic to heteroclinic) due to separatrix reconnection. We show that a similar but more complex scenario appears in the case of particle orbits that depend in a non-trivial way on the energy and pitch angle of the

  8. Development of efficient RNA interference system using EGF-displaying phagemid particles

    Institute of Scientific and Technical Information of China (English)

    Hua JIANG; Xiu-mei CAI; Bi-zhi SHI; Jie ZHANG; Zong-hai LI; Jian-ren GU

    2008-01-01

    Aim:To develop an efficient RNA interference system using phagemid particles displaying the epidermal growth factor (EGF) ligand. Methods:pSilencer 1.0-siEGFP and pSilencer4.1-siAkt plasmids were constructed by gene clone technology. The modified helper phage genome (plasmid) M 13KO7EGFCT was used to pack-age phagemids, such as pSilencer 1.0-siEGFP and pSilencer4.1-siAkt. ELISA was used to quantify the titer of the progeny virus particles. Single-strand DNA was extracted and analyzed by agarose gel electrophoresis to evaluate the percentage of the phagemid particles. The expression level of the reporter gene enhanced green fluorescence protein (EGFP) was determined by transducing phagemid par-ticles packaging pSileneer 1.0-siEGFP into cells. The level of Akt gene expression in cells transduced phagemid particles packaging pSilencer4. 1-siAkt was exam-ined by Western blotting. Hydroxycamptothecin (HCPT) was used to enhance the gene transduction efficiency. Results:RNAi vectors pSilencer1.0-siEGFP and pSilencer4.1-siAkt were successfully constructed. Phagemid-encoding siRNA can be packaged efficiently. After the cells were infected by EGF displaying phagemid particles in the presence of HCPT, the expression of the target gene EGFPor Akt was substantially downregulated. Conclusion:Cell-targeted phagemid particles are efficient siRNA delivery vectors in the presence of HCPT.

  9. Prospective of ultradispersic magnetic particles in biological experiments in microgravity

    Science.gov (United States)

    Nechitailo, Galina S.; Kuznetsov, Anatoli; Malashin, S.

    All organisms on Earth use gravity for their lifecycles. Microgravity disturbs the lifecycles significantly: orientation ability is damaged, thermo and mass exchange processes are changed, adaptation mechanisms are destroyed. A recovering the normal life cycle of organism in future long-term mission requires an artificial gravity which is complicate and not realistic with present technologies. We propose to use a magnetic properties of the biological objects for recovering of the gravity-dependent biological processes in organism during space flight. Based on result of magnetic properties investigation in gravity-sensitive plant cells, we have prepared and carried out the experiments on space station MIR. For the experiments, Magnitogravistat device was designed and installed on the station. The aim of the experiment was to replace a gravity factor of plant with a magnetic factor. The magnetic effect is based on the fact, that a magnetic particle of V volume is under the force F=ΔæVHgradH in the magnetic gradient gradH, where Δæ is the difference between the magnetic susceptibility of particle and media. When the particles are placed into the cell, the cell can be managed by the magnetic field. In laboratory experiment the iron-carbon particles of 1-2 um with nanostructurised surface and high adsorption properties have been used. The particles can be suspended in water and adsorbed chemicals including cell metabolites. In strong magnetic field, the particles can be agglomerated and the liquid substrate can be replaced. The local magnetic field near the particles can influence on cell processes. The magnetic field causes a cell differentiation and can influence on cell proliferation. A new space experiment with magnetic particles is planned to get a knowledge on cell influence and to improve a cell metabolism.

  10. A biodetection method using magnetic particles and micro traps

    KAUST Repository

    Li, Fuquan

    2012-03-09

    The general working principle of magnetoresistive sensors for biological applications is to specifically attach bioanalytesto magnetic particles and then detect the particles that are immobilized on the sensor surface. The immobilization of the particles on the sensor surface commonly uses biomolecular interactions, e.g., antigen-antibody. Thus, the sensor surface needs to be functionalized via biological treatments in order to capture certain bioanalytes. In the presented work, a new method is proposed, which does not rely on functionalization of the sensor surface. Current carrying microstructures in combination with mechanical micro traps are used to immobilize magnetic particles. Analyte detection is based on the difference in size between bare magnetic particles and particles with analyte attached, which causes a different number of particles to be captured in the micro traps.

  11. Quantifying the motion of magnetic particles in excised tissue: Effect of particle properties and applied magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Kulkarni, Sandip, E-mail: sandip.d.kulkarni@gmail.com [Fischell Department of Bioengineering, University of Maryland at College Park, MD 20742 (United States); Ramaswamy, Bharath; Horton, Emily; Gangapuram, Sruthi [Fischell Department of Bioengineering, University of Maryland at College Park, MD 20742 (United States); Nacev, Alek [Weinberg Medical Physics, LLC (United States); Depireux, Didier [The Institute for Systems Research, University of Maryland at College Park, MD 20742 (United States); Otomagnetics, LLC (United States); Shimoji, Mika [Fischell Department of Bioengineering, University of Maryland at College Park, MD 20742 (United States); Otomagnetics, LLC (United States); Shapiro, Benjamin [Fischell Department of Bioengineering, University of Maryland at College Park, MD 20742 (United States); The Institute for Systems Research, University of Maryland at College Park, MD 20742 (United States); Otomagnetics, LLC (United States)

    2015-11-01

    This article presents a method to investigate how magnetic particle characteristics affect their motion inside tissues under the influence of an applied magnetic field. Particles are placed on top of freshly excised tissue samples, a calibrated magnetic field is applied by a magnet underneath each tissue sample, and we image and quantify particle penetration depth by quantitative metrics to assess how particle sizes, their surface coatings, and tissue resistance affect particle motion. Using this method, we tested available fluorescent particles from Chemicell of four sizes (100 nm, 300 nm, 500 nm, and 1 μm diameter) with four different coatings (starch, chitosan, lipid, and PEG/P) and quantified their motion through freshly excised rat liver, kidney, and brain tissues. In broad terms, we found that the applied magnetic field moved chitosan particles most effectively through all three tissue types (as compared to starch, lipid, and PEG/P coated particles). However, the relationship between particle properties and their resulting motion was found to be complex. Hence, it will likely require substantial further study to elucidate the nuances of transport mechanisms and to select and engineer optimal particle properties to enable the most effective transport through various tissue types under applied magnetic fields.

  12. An Electrochemiluminescence Immunosensor Based on Gold-Magnetic Nanoparticles and Phage Displayed Antibodies.

    Science.gov (United States)

    Mu, Xihui; Tong, Zhaoyang; Huang, Qibin; Liu, Bing; Liu, Zhiwei; Hao, Lanqun; Dong, Hua; Zhang, Jinping; Gao, Chuan

    2016-02-27

    Using the multiple advantages of the ultra-highly sensitive electrochemiluminescence (ECL) technique, Staphylococcus protein A (SPA) functionalized gold-magnetic nanoparticles and phage displayed antibodies, and using gold-magnetic nanoparticles coated with SPA and coupled with a polyclonal antibody (pcAb) as magnetic capturing probes, and Ru(bpy)₃(2+)-labeled phage displayed antibody as a specific luminescence probe, this study reports a new way to detect ricin with a highly sensitive and specific ECL immunosensor and amplify specific detection signals. The linear detection range of the sensor was 0.0001~200 µg/L, and the limit of detection (LOD) was 0.0001 µg/L, which is 2500-fold lower than that of the conventional ELISA technique. The gold-magnetic nanoparticles, SPA and Ru(bpy)₃(2+)-labeled phage displayed antibody displayed different amplifying effects in the ECL immunosensor and can decrease LOD 3-fold, 3-fold and 20-fold, respectively, compared with the ECL immunosensors without one of the three effects. The integrated amplifying effect can decrease the LOD 180-fold. The immunosensor integrates the unique advantages of SPA-coated gold-magnetic nanoparticles that improve the activity of the functionalized capturing probe, and the amplifying effect of the Ru(bpy)₃(2+)-labeled phage displayed antibodies, so it increases specificity, interference-resistance and decreases LOD. It is proven to be well suited for the analysis of trace amounts of ricin in various environmental samples with high recovery ratios and reproducibility.

  13. An Electrochemiluminescence Immunosensor Based on Gold-Magnetic Nanoparticles and Phage Displayed Antibodies

    Directory of Open Access Journals (Sweden)

    Xihui Mu

    2016-02-01

    Full Text Available Using the multiple advantages of the ultra-highly sensitive electrochemiluminescence (ECL technique, Staphylococcus protein A (SPA functionalized gold-magnetic nanoparticles and phage displayed antibodies, and using gold-magnetic nanoparticles coated with SPA and coupled with a polyclonal antibody (pcAb as magnetic capturing probes, and Ru(bpy32+-labeled phage displayed antibody as a specific luminescence probe, this study reports a new way to detect ricin with a highly sensitive and specific ECL immunosensor and amplify specific detection signals. The linear detection range of the sensor was 0.0001~200 µg/L, and the limit of detection (LOD was 0.0001 µg/L, which is 2500-fold lower than that of the conventional ELISA technique. The gold-magnetic nanoparticles, SPA and Ru(bpy32+-labeled phage displayed antibody displayed different amplifying effects in the ECL immunosensor and can decrease LOD 3-fold, 3-fold and 20-fold, respectively, compared with the ECL immunosensors without one of the three effects. The integrated amplifying effect can decrease the LOD 180-fold. The immunosensor integrates the unique advantages of SPA-coated gold-magnetic nanoparticles that improve the activity of the functionalized capturing probe, and the amplifying effect of the Ru(bpy32+-labeled phage displayed antibodies, so it increases specificity, interference-resistance and decreases LOD. It is proven to be well suited for the analysis of trace amounts of ricin in various environmental samples with high recovery ratios and reproducibility.

  14. Iron free permanent magnet systems for charged particle beam optics

    Energy Technology Data Exchange (ETDEWEB)

    Lund, S.M.; Halbach, K.

    1995-09-03

    The strength and astounding simplicity of certain permanent magnet materials allow a wide variety of simple, compact configurations of high field strength and quality multipole magnets. Here we analyze the important class of iron-free permanent magnet systems for charged particle beam optics. The theory of conventional segmented multipole magnets formed from uniformly magnetized block magnets placed in regular arrays about a circular magnet aperture is reviewed. Practical multipole configurations resulting are presented that are capable of high and intermediate aperture field strengths. A new class of elliptical aperture magnets is presented within a model with continuously varying magnetization angle. Segmented versions of these magnets promise practical high field dipole and quadrupole magnets with an increased range of applicability.

  15. Electrically operated magnetic switch designed to display reduced leakage inductance

    Science.gov (United States)

    Cook, Edward G.

    1994-01-01

    An electrically operated magnetic switch is disclosed herein for use in opening and closing a circuit between two terminals depending upon the voltage across these terminals. The switch so disclosed is comprised of a ferrite core in the shape of a toroid having opposing ends and opposite inner and outer sides and an arrangement of electrically conductive components defining at least one current flow path which makes a number of turns around the core. This arrangement of components includes a first plurality of electrically conducive rigid rods parallel with and located outside the outer side of the core and a second plurality of electrically conductive rigid rods parallel with and located inside the inner side of the core. The arrangement also includes means for electrically connecting these rods together so that the define the current flow path. In one embodiment, this latter means uses rigid cross-tab means. In another, preferred embodiment, printed circuits on rigid dielectric substrates located on opposite ends of the core are utilized to interconnect the rods together.

  16. A magnetometer for estimating the magnetic moment of magnetic micro-particles

    Science.gov (United States)

    Punyabrahma, P.; Jayanth, G. R.

    2017-01-01

    Magnetic micro-particles find a variety of applications as actuators at the micrometer and nanometer length scales. While the actuation gain is directly proportional to their magnetic moment, there are relatively few technologies available to estimate the magnetic moment of individual magnetic particles. This paper proposes a magnetometer for direct measurement of the magnetic moment of ferromagnetic micro-particles. The magnetometer comprises a novel micro-scale force sensor capable of interacting with magnetic particles and deflecting in response to the force of interaction. It also comprises a high-resolution measurement system, a source of magnetizing field, and a nanopositioner. The principle of operation of the magnetometer is discussed and is shown to enable the determination of the magnetic moment even of the buried magnetic particles, and those of irregular geometry. Subsequently, the force sensor, the measurement system, and the magnetic field sources are designed, fabricated, and calibrated. Finally, the magnetometer is employed to measure the magnetic moments of both fixed and untethered permanent magnetic particles and also of a fixed soft ferromagnetic particle. In all cases, the estimated magnetic moment is shown to agree with the theoretical estimate with an average error of about 16%.

  17. Magnetic moment conservation and particles acceleration in turbulence

    Science.gov (United States)

    Dalena, S.; Greco, A.; Matthaeus, W. H.

    2010-12-01

    The present work concerns the study of particle magnetic moment conservation in the presence of turbulent magnetic fields. As we know from the particle orbit theory, for slow temporal and spatial magnetic field variations(i.e. if their characteristic length and time are greater than the particle orbit diameter and the time spent by a particle to execute one orbit, respectively), the magnetic moment, defined as μ = (v^2⊥ /B) (averaged over the particle gyroperiod) is an adiabatic invariant and remains constant during particle motion. But in presence of a well developed magnetic turbulence μ can undergo rapid variations and might not be constant anymore. Of course, this fact could influence particle acceleration and could have a considerable implications in many astrophysical problems, such as coronal heating. In order to reproduce and extend some of the results obtained by Karimabadi et al. 1992, we study the interaction between ions and a single or a couple of electromagnetic waves. We varied both the wave frequency and the cosine of pitch angle at which particles are injected, in order to observe in this very simple case which is the limit for magnetic moment conservation. We also will reconsider the results of Dmitruk and Matthaeus (2006) regarding particle acceleration in turbulence, taking into account statistics of the magnetic moment (see also Lehe et al., 2010). Later we will add more waves to obtain a complete turbulent spectrum. The final aim of this research work is the understanding the behavior of particles magnetic moment during magnetic reconnection phenomena. H. Karimabadi, D. Krauss-Varban and T. Teresawa, JGR, 97, 13853, 1992. P. Dmitruk and W. H. Matthaeus, JGR, 11, A12110, 2006. R. Lehe, I. J. Parrish and E. Quataert, Astrophys. J. 707, 404, 2009.

  18. Engineering RNA phage MS2 virus-like particles for peptide display

    Science.gov (United States)

    Jordan, Sheldon Keith

    Phage display is a powerful and versatile technology that enables the selection of novel binding functions from large populations of randomly generated peptide sequences. Random sequences are genetically fused to a viral structural protein to produce complex peptide libraries. From a sufficiently complex library, phage bearing peptides with practically any desired binding activity can be physically isolated by affinity selection, and, since each particle carries in its genome the genetic information for its own replication, the selectants can be amplified by infection of bacteria. For certain applications however, existing phage display platforms have limitations. One such area is in the field of vaccine development, where the goal is to identify relevant epitopes by affinity-selection against an antibody target, and then to utilize them as immunogens to elicit a desired antibody response. Today, affinity selection is usually conducted using display on filamentous phages like M13. This technology provides an efficient means for epitope identification, but, because filamentous phages do not display peptides in the high-density, multivalent arrays the immune system prefers to recognize, they generally make poor immunogens and are typically useless as vaccines. This makes it necessary to confer immunogenicity by conjugating synthetic versions of the peptides to more immunogenic carriers. Unfortunately, when introduced into these new structural environments, the epitopes often fail to elicit relevant antibody responses. Thus, it would be advantageous to combine the epitope selection and immunogen functions into a single platform where the structural constraints present during affinity selection can be preserved during immunization. This dissertation describes efforts to develop a peptide display system based on the virus-like particles (VLPs) of bacteriophage MS2. Phage display technologies rely on (1) the identification of a site in a viral structural protein that is

  19. An experimental and numerical investigation of flat panel display cell using magnetic fluid

    CERN Document Server

    Seo, J W; Park, S J; Lee, H S

    2002-01-01

    Optical and fluid dynamical properties of magnetic fluid have been studied experimentally and numerically using a test device with a water-base magnetite magnetic fluid. It has been found that the 3.5 mu m thick fluid film absorbs most of the incoming visible light and can be actuated fast enough to realize display devices. The computational simulation shows that the surface tension of the liquid plays the most dominant roles for the test device, and a device that can actuate the magnetic fluid magnetically is proposed.

  20. Micro-magnetic simulation study on the magnetic particle imaging performance of anisotropic mono-domain particles.

    Science.gov (United States)

    Weizenecker, Jürgen; Gleich, Bernhard; Rahmer, Jürgen; Borgert, Jörn

    2012-11-21

    The performance of magnetic mono-domain particles is of crucial importance in magnetic particle imaging (MPI). So far, the behavior of mono-domain particles has been modeled within the framework of Langevin theory. This theory predicts the dependence of the MPI signal on the particle core size, but cannot account for the influence of the shape, i.e. the anisotropy of the particle core. In this study we present the first micro-magnetic ab initio simulation of spectra of anisotropic particles with different core diameters in an oscillating magnetic field at 25 and 100 kHz. We find that the MPI signal strongly depends on the anisotropy of the magnetic core. Thus, a difference of 3 nm between the principal axes of a prolate ellipsoid with the volume of a 30 nm sphere can result in a complete loss of the MPI signal. Smaller anisotropies, however, can increase the MPI performance of the particle. The simulations show that the effect of the anisotropy on the MPI signal depends on the frequency of the oscillating magnetic field. At 100 kHz, the optimal signal is found at smaller anisotropies than at 25 kHz. Furthermore, the simulations show that experimental spectroscopic results for Resovist® can only be explained quantitatively by particles with a magnetic core size of at least 25 nm.

  1. Measurement of magnetic fluctuation-induced particle flux (invited).

    Science.gov (United States)

    Ding, W X; Brower, D L; Yates, T Y

    2008-10-01

    Magnetic field fluctuation-induced particle transport has been directly measured in the high-temperature core of the MST reversed field pinch plasma. Measurement of radial particle transport is achieved by combining various interferometry techniques, including Faraday rotation, conventional interferometry, and differential interferometry. It is observed that electron convective particle flux and its divergence exhibit a significant increase during a sawtooth crash. In this paper, we describe the basic techniques employed to determine the particle flux.

  2. Review- Numerical simulation of chainlike cluster movement of feeble magnetic particles by induced magnetic dipole moment under high magnetic fields

    Directory of Open Access Journals (Sweden)

    Tsutomu Ando, Noriyuki Hirota and Hitoshi Wada

    2009-01-01

    Full Text Available In this paper, the motion of a chainlike cluster of feeble magnetic particles induced by high magnetic field is discussed on the basis of the results of numerical simulations. The simulations were performed on glass particles with a diameter of 0.8 mm; and the viscosity, applied magnetic field and magnetic properties of the surrounding medium were changed. In addition to the magnetic field and the difference in magnetic susceptibility between the particles and the surrounding medium, the obtained results indicate that the viscosity is an essential factor for the formation of the chainlike alignment of feeble magnetic particles. We also carried out simulations using glass particles with a smaller diameter of 0.1 mm. Chainlike clusters were produced similar to those of ferromagnetic particles formed in a ferromagnetic fluid.

  3. Magnetofluidic concentration and separation of non-magnetic particles using two magnet arrays.

    Science.gov (United States)

    Hejazian, Majid; Nguyen, Nam-Trung

    2016-07-01

    The present paper reports the use of diluted ferrofluid and two arrays of permanent magnets for the size-selective concentration of non-magnetic particles. The micro magnetofluidic device consists of a straight channels sandwiched between two arrays of permanent magnets. The permanent magnets create multiple capture zones with minimum magnetic field strength along the channel. The complex interaction between magnetic forces and hydrodynamic force allows the device to operate in different regimes suitable for concentration of non-magnetic particles with small difference in size. Our experimental results show that non-magnetic particles with diameters of 3.1 μm and 4.8 μm can be discriminated and separated with this method. The results from this study could be used as a guide for the design of size-sensitive separation devices for particle and cell based on negative magnetophoresis.

  4. Magnetized Particle Motion Around Black Hole in Braneworld

    CERN Document Server

    Rahimov, Ozodbek

    2010-01-01

    We investigate the motion of a magnetized particle orbiting around a black hole in braneworld placed in asymptotically uniform magnetic field. The influence of brane parameter on effective potential of the radial motion of magnetized spinning particle around the braneworld black hole using Hamilton-Jacobi formalism is studied. It is found that circular orbits for photons and slowly moving particles may become stable near $r = 3M$. It was argued that the radii of the innermost stable circular orbits are sensitive on the change of brane parameter. Similar discussion without Weil parameter has been considered by de Felice et all in~Ref. \\refcite{rs99,98}.

  5. Thermal Stability of RNA Phage Virus-Like Particles Displaying Foreign Peptides

    Directory of Open Access Journals (Sweden)

    Peabody David S

    2011-05-01

    Full Text Available Abstract Background To be useful for genetic display of foreign peptides a viral coat protein must tolerate peptide insertions without major disruption of subunit folding and capsid assembly. The folding of the coat protein of RNA phage MS2 does not normally tolerate insertions in its AB-loop, but an engineered single-chain dimer readily accepts them as long as they are restricted to one of its two halves. Results Here we characterize the effects of peptide insertions on the thermal stabilities of MS2 virus-like particles (VLPs displaying a variety of different peptides in one AB-loop of the coat protein single-chain dimer. These particles typically denature at temperatures around 5-10°C lower than unmodified VLPs. Even so, they are generally stable up to about 50°C. VLPs of the related RNA phage PP7 are cross-linked with intersubunit disulfide bonds and are therefore significantly more stable. An AB-loop insertion also reduces the stability of PP7 VLPs, but they only begin to denature above about 70°C. Conclusions VLPs assembled from MS2 single-chain dimer coat proteins with peptide insertions in one of their AB-loops are somewhat less stable than the wild-type particle, but still resist heating up to about 50°C. Because they possess disulfide cross-links, PP7-derived VLPs provide an alternate platform with even higher stability.

  6. Magnetic properties of magnetic liquids with iron-oxide particles - the influence of anisotropy and interactions

    DEFF Research Database (Denmark)

    Johansson, C.; Hanson, M.; Pedersen, Michael Stanley

    1997-01-01

    Magnetic liquids containing iron-oxide particles were investigated by magnetization and Mossbauer measurements. The particles were shown to be maghemite with a spontanious saturation magentization Ms = 320 kA m-1 at 200 K and a normalized high-field susceptibility x/M0 = 5.1x10-6 mkA-1, practical......-field-cooled magnetization and isothermal remanence decay, is influenced by interactions and strongly dependent on the applied magnetic field....

  7. Preparation of magnetic polymer particles with nanoparticles of Fe(0).

    Science.gov (United States)

    Buendía, S; Cabañas, G; Alvarez-Lucio, G; Montiel-Sánchez, H; Navarro-Clemente, M E; Corea, M

    2011-02-01

    Iron nanoparticles (Fe(0)), were encapsulated into polymethyl methacrylate (PMMA), by means of emulsion polymerization techniques in a semicontinuous process. The final average diameter of the composite particle was calculated until three times of average particle of iron particles and were stabilized with a non-ionic surfactant. They were then characterized by scanning electron microscopy and dynamic light scattering. Their magnetic properties were determined by parallel field vibrating-sample magnetometry method. The results indicated that the magnetic properties are a function of polymer concentration in the nanocomposite particle.

  8. Self-consistent magnetic properties of magnetite tracers optimized for magnetic particle imaging measured by ac susceptometry, magnetorelaxometry and magnetic particle spectroscopy

    Science.gov (United States)

    Ludwig, Frank; Remmer, Hilke; Kuhlmann, Christian; Wawrzik, Thilo; Arami, Hamed; Ferguson, R. Mathew; Krishnan, Kannan M.

    2014-06-01

    Sensitivity and spatial resolution in magnetic particle imaging are affected by magnetic properties of the nanoparticle tracers used during imaging. Here, we have carried out a comprehensive magnetic characterization of single-core iron oxide nanoparticles that were designed for MPI. We used ac susceptometry, fluxgate magnetorelaxometry, and magnetic particle spectroscopy to evaluate the tracer's magnetic core size, hydrodynamic size, and magnetic anisotropy. Our results present a self-consistent set of magnetic and structural parameters for the tracers that is consistent with direct measurements of size using transmission electron microscopy and dynamic light scattering and that can be used to better understand their MPI performance.

  9. Self-consistent magnetic properties of magnetite tracers optimized for magnetic particle imaging measured by ac susceptometry, magnetorelaxometry and magnetic particle spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ludwig, Frank; Remmer, Hilke; Kuhlmann, Christian; Wawrzik, Thilo [Institute of Electrical Measurement and Fundamental Electrical Engineering, TU Braunschweig, Hans-Sommer-Str. 66, D-38106 Braunschweig (Germany); Arami, Hamed; Ferguson, R. Mathew [Department of Materials Science and Engineering Box 352120, University of Washington, Seattle, WA 98195 (United States); Krishnan, Kannan M., E-mail: kannanmk@uw.edu [Department of Materials Science and Engineering Box 352120, University of Washington, Seattle, WA 98195 (United States)

    2014-06-01

    Sensitivity and spatial resolution in magnetic particle imaging are affected by magnetic properties of the nanoparticle tracers used during imaging. Here, we have carried out a comprehensive magnetic characterization of single-core iron oxide nanoparticles that were designed for MPI. We used ac susceptometry, fluxgate magnetorelaxometry, and magnetic particle spectroscopy to evaluate the tracer's magnetic core size, hydrodynamic size, and magnetic anisotropy. Our results present a self-consistent set of magnetic and structural parameters for the tracers that is consistent with direct measurements of size using transmission electron microscopy and dynamic light scattering and that can be used to better understand their MPI performance.

  10. Magnetic stochasticity in magnetically confined fusion plasmas chaos of field lines and charged particle dynamics

    CERN Document Server

    Abdullaev, Sadrilla

    2014-01-01

    This is the first book to systematically consider the modern aspects of chaotic dynamics of magnetic field lines and charged particles in magnetically confined fusion plasmas.  The analytical models describing the generic features of equilibrium magnetic fields and  magnetic perturbations in modern fusion devices are presented. It describes mathematical and physical aspects of onset of chaos, generic properties of the structure of stochastic magnetic fields, transport of charged particles in tokamaks induced by magnetic perturbations, new aspects of particle turbulent transport, etc. The presentation is based on the classical and new unique mathematical tools of Hamiltonian dynamics, like the action--angle formalism, classical perturbation theory, canonical transformations of variables, symplectic mappings, the Poincaré-Melnikov integrals. They are extensively used for analytical studies as well as for numerical simulations of magnetic field lines, particle dynamics, their spatial structures and  statisti...

  11. Strong magnetic response of submicron Silicon particles in the infrared

    CERN Document Server

    Garcia-Etxarri, A; Froufe-Perez, L S; Lopez, C; Chantada, L; Scheffold, F; Aizpurua, J; Nieto-Vesperinas, M; Saenz, J J

    2010-01-01

    High-permittivity dielectric particles with resonant magnetic properties are being explored as constitutive elements of new metamaterials and devices in the microwave regime. Magnetic properties of low-loss dielectric nanoparticles in the visible or infrared are not expected due to intrinsic low refractive index of optical materials in these regimes. Here we analyze the dipolar electric and magnetic response of loss-less dielectric spheres made of moderate permittivity materials. For low material refractive index there are no sharp resonances due to strong overlapping between different multipole contributions. However, we find that Silicon particles with refractive index 3.5 and radius approx. 200nm present a dipolar and strong magnetic resonant response in telecom and near-infrared frequencies, (i.e. at wavelengths approx. 1.2-2 micrometer). Moreover, the light scattered by these Si particles can be perfectly described by dipolar electric and magnetic fields, quadrupolar and higher order contributions being ...

  12. Stochastic particle acceleration in multiple magnetic islands during reconnection.

    Science.gov (United States)

    Hoshino, Masahiro

    2012-03-30

    A nonthermal particle acceleration mechanism involving the interaction of a charged particle with multiple magnetic islands is proposed. The original Fermi acceleration model, which assumes randomly distributed magnetic clouds moving at random velocity V(c) in the interstellar medium, is known to be of second-order acceleration of O(V(c)/c)(2) owing to the combination of head-on and head-tail collisions. In this Letter, we reconsider the original Fermi model by introducing multiple magnetic islands during reconnection instead of magnetic clouds. We discuss that the energetic particles have a tendency to be distributed outside the magnetic islands, and they mainly interact with reconnection outflow jets. As a result, the acceleration efficiency becomes first order of O(V(A)/c), where V(A) and c are the Alfvén velocity and the speed of light, respectively.

  13. Brownian Dynamics of charged particles in a constant magnetic field

    CERN Document Server

    Hou, L J; Piel, A; Shukla, P K

    2009-01-01

    Numerical algorithms are proposed for simulating the Brownian dynamics of charged particles in an external magnetic field, taking into account the Brownian motion of charged particles, damping effect and the effect of magnetic field self-consistently. Performance of these algorithms is tested in terms of their accuracy and long-time stability by using a three-dimensional Brownian oscillator model with constant magnetic field. Step-by-step recipes for implementing these algorithms are given in detail. It is expected that these algorithms can be directly used to study particle dynamics in various dispersed systems in the presence of a magnetic field, including polymer solutions, colloidal suspensions and, particularly complex (dusty) plasmas. The proposed algorithms can also be used as thermostat in the usual molecular dynamics simulation in the presence of magnetic field.

  14. Adsorption of Proteins with Tannin Modified Chitosan Magnetic Particles

    Institute of Scientific and Technical Information of China (English)

    CHANG Yue; SU ZhiXing; WANG YunPu

    2001-01-01

    @@ Magnetic polymer particles have been widely used in biochemistry and medicine in recent years [1-4], mainly due to their property of relatively rapid and easy separation. There were many ways for preparation of magnetic particles [5-9]. We know natural polymer having convenient site such as-NH2,-COOH,-OH,-CONH2, etc. for the affinity ligand attachment. The literature reported chitosan as magnetic polymer matrix, dye as affinity ligand to purify bovine serum albumin and lysozyme[10l. Tannin, a natural product having multiple adjacent hydroxy groups, has extremely high affinity to adsorb protein or alkaloid. However, the information about tannin modified magnetic support is still sparse. Therefore, tannin modified chitosan magnetic particle was prepared and the adsorption of trypsin and aprotinin were studied.

  15. Adsorption of Proteins with Tannin Modified Chitosan Magnetic Particles

    Institute of Scientific and Technical Information of China (English)

    CHANG; Yue

    2001-01-01

    Magnetic polymer particles have been widely used in biochemistry and medicine in recent years [1-4], mainly due to their property of relatively rapid and easy separation. There were many ways for preparation of magnetic particles [5-9]. We know natural polymer having convenient site such as-NH2,-COOH,-OH,-CONH2, etc. for the affinity ligand attachment. The literature reported chitosan as magnetic polymer matrix, dye as affinity ligand to purify bovine serum albumin and lysozyme[10l. Tannin, a natural product having multiple adjacent hydroxy groups, has extremely high affinity to adsorb protein or alkaloid. However, the information about tannin modified magnetic support is still sparse. Therefore, tannin modified chitosan magnetic particle was prepared and the adsorption of trypsin and aprotinin were studied.……

  16. Fermionic Particle Production by Varying Electric and Magnetic Fields

    Science.gov (United States)

    Sogut, Kenan; Yanar, Hilmi; Havare, Ali

    2016-11-01

    Creation of fermionic particles by a time-dependent electric field and a space-dependent magnetic field is studied with the Bogoulibov transformation method. Exact analytic solutions of the Dirac equation are obtained in terms of the Whittaker functions and the particle creation number density depending on the electric and magnetic fields is determined. Supported by the Research Fund of Mersin University in TURKEY with project number: 2016-1-AP4-1425

  17. Magnetic properties of hybrid elastomers with magnetically hard fillers: rotation of particles

    Science.gov (United States)

    Stepanov, G. V.; Borin, D. Yu; Bakhtiiarov, A. V.; Storozhenko, P. A.

    2017-03-01

    Hybrid magnetic elastomers belonging to the family of magnetorheological elastomers contain magnetically hard components and are of the utmost interest for the development of semiactive and active damping devices as well as actuators and sensors. The processes of magnetizing of such elastomers are accompanied by structural rearrangements inside the material. When magnetized, the elastomer gains its own magnetic moment resulting in changes of its magneto-mechanical properties, which remain permanent, even in the absence of external magnetic fields. Influenced by the magnetic field, magnetized particles move inside the matrix forming chain-like structures. In addition, the magnetically hard particles can rotate to align their magnetic moments with the new direction of the external field. Such an elastomer cannot be demagnetized by the application of a reverse field.

  18. Lens-free imaging of magnetic particles in DNA assays.

    Science.gov (United States)

    Colle, Frederik; Vercruysse, Dries; Peeters, Sara; Liu, Chengxun; Stakenborg, Tim; Lagae, Liesbet; Del-Favero, Jurgen

    2013-11-01

    We present a novel opto-magnetic system for the fast and sensitive detection of nucleic acids. The system is based on a lens-free imaging approach resulting in a compact and cheap optical readout of surface hybridized DNA fragments. In our system magnetic particles are attracted towards the detection surface thereby completing the labeling step in less than 1 min. An optimized surface functionalization combined with magnetic manipulation was used to remove all nonspecifically bound magnetic particles from the detection surface. A lens-free image of the specifically bound magnetic particles on the detection surface was recorded by a CMOS imager. This recorded interference pattern was reconstructed in software, to represent the particle image at the focal distance, using little computational power. As a result we were able to detect DNA concentrations down to 10 pM with single particle sensitivity. The possibility of integrated sample preparation by manipulation of magnetic particles, combined with the cheap and highly compact lens-free detection makes our system an ideal candidate for point-of-care diagnostic applications.

  19. Particle acceleration near magnetic nulls using MMS data

    Science.gov (United States)

    Eriksson, Elin; Vaivads, Andris; Khotyaintsev, Yuri; Graham, Daniel; Markidis, Stefano; Peng, Ivy Bo; André, Mats; Burch, James; Lindqvist, Per-Arne; Ergun, Robert; Torbert, Roy; Magnes, Werner; Russell, Christopher; Giles, Barbara; Pollock, Craig

    2016-04-01

    Regions with vanishing magnetic field, also referred to as magnetic nulls, are of high interest in plasma physics. Near magnetic nulls particles become unmagnetized and can by interacting with electric fields be accelerated up to high energies. Magnetic nulls have been observed and studied before using using Cluster data with different methods. Magnetic nulls found by Cluster have been obtained with spacecraft separation comparable to ion scales and particle instrumentation is not sufficient to resolve in detail physical processes of particle acceleration around the null. Now we use the MMS (Magnetospheric Multiscale) data to study these processes in detail. The MMS separation is well below the ion scale and data from particle instruments has sufficient resolution during burst mode to resolve these processes for our events. We study nulls in detail during phase 1a of the MMS mission. Burst data during this phase are mainly from the magnetopause, but some intervals cover the magnetosheath, bowshock, and solar wind. We particularly focus on magnetic nulls associated with strong currents, which can potentially be associated with the electron diffusion region of magnetic reconnection. There we also expect particle acceleration to occur. A preliminary study has already identified several nulls of high interest in the burst data. We present a detailed study of these nulls.

  20. Hysteresis of the Magnetic Particle in a Dipolar Ising Model

    Institute of Scientific and Technical Information of China (English)

    WU Yin-Zhong; LI Zhen-Ya

    2002-01-01

    Zero-temperature Monte Carlo simulations are used to investigate the hysteresis of a magnetic particle ina dipolarIsing model. The magnetic particle is described in a system of permanent dipoles, and the dipoles are locatedin a cubic lattice site. The effects of the shape and the size of the particle on the hysteresis loop at zero temperatureare obtained. For strong exchange interactions, the shapes of magnetic hysteresis loops approach rectangle. For weakexchange interactions, the effects of the size and the shape of the particle on the loops are more remarkable than thoseof strong exchange interactions case. The slope of the hysteresis loop decreases with the increase of the ratio of thesemi major axis to the semi minor axis of the ellipsoidal magnetic particle, and there is an increase of the slope of thehysteresis with the decrease of the size of the magnetic particle. The effects of the shape and size of the particle on thecoercive force at zero temperature are also investigated.

  1. Reactivation from latency displays HIV particle budding at plasma membrane, accompanying CD44 upregulation and recruitment

    Directory of Open Access Journals (Sweden)

    Sano Kouichi

    2009-07-01

    Full Text Available Abstract Background It has been accepted that HIV buds from the cell surface in T lymphocytes, whereas in macrophages it buds into intracellular endosomes. Recent studies, on the other hand, suggest that HIV preferentially buds from the cell surface even in monocytic cells. However, most studies are based on observations in acutely infected cells and little is known about HIV budding concomitant with reactivation from latency. Such studies would provide a better understanding of a reservoir for HIV. Results We observed HIV budding in latently infected T lymphocytic and monocytic cell lines following TNF-α stimulation and examined the upregulation of host factors that may be involved in particle production. Electron microscopy analysis revealed that reactivation of latently infected J1.1 cells (latently infected Jurkat cells with HIV-1 and U1 cells (latently infected U937 cells with HIV-1 displayed HIV particle budding predominantly at the plasma membrane, a morphology that is similar to particle budding in acutely infected Jurkat and U937 cells. When mRNA expression levels were quantified by qRT-PCR, we found that particle production from reactivated J1.1 and U1 cells was accompanied by CD44 upregulation. This upregulation was similarly observed when Jurkat and U937 cells were acutely infected with HIV-1 but not when just stimulated with TNF-α, suggesting that CD44 upregulation was linked with HIV production but not with cell stimulation. The molecules in endocytic pathways such as CD63 and HRS were also upregulated when U1 cells were reactivated and U937 cells were acutely infected with HIV-1. Confocal microscopy revealed that these upregulated host molecules were recruited to and accumulated at the sites where mature particles were formed at the plasma membrane. Conclusion Our study indicates that HIV particles are budded at the plasma membrane upon reactivation from latency, a morphology that is similar to particle budding in acute

  2. Magnetic core-shell silica particles

    NARCIS (Netherlands)

    Claesson, E.M.

    2007-01-01

    This thesis deals with magnetic silica core-shell colloids and related functionalized silica structures. Synthesis routes have been developed and optimized. The physical properties of these colloids have been investigated, such as the magnetic dipole moment, dipolar structure formation and

  3. Magnetic core-shell silica particles

    NARCIS (Netherlands)

    Claesson, E.M.

    2007-01-01

    This thesis deals with magnetic silica core-shell colloids and related functionalized silica structures. Synthesis routes have been developed and optimized. The physical properties of these colloids have been investigated, such as the magnetic dipole moment, dipolar structure formation and rotationa

  4. The advantages and challenges of superconducting magnets in particle therapy

    Science.gov (United States)

    Gerbershagen, Alexander; Calzolaio, Ciro; Meer, David; Sanfilippo, Stéphane; Schippers, Marco

    2016-08-01

    This paper provides an overview of the current developments in superconducting magnets for applications in proton and ion therapy. It summarizes the benefits and challenges regarding the utilization of these magnets in accelerating systems (e.g. superconducting cyclotrons) and gantries. The paper also provides examples of currently used superconducting particle therapy systems and proposed designs.

  5. Microstripes for transport and separation of magnetic particles

    DEFF Research Database (Denmark)

    Donolato, Marco; Dalslet, Bjarke Thomas; Hansen, Mikkel Fougt

    2012-01-01

    We present a simple technique for creating an on-chip magnetic particle conveyor based on exchange-biased permalloy microstripes. The particle transportation relies on an array of stripes with a spacing smaller than their width in conjunction with a periodic sequence of four different externally...

  6. Particle size- and concentration-dependent separation of magnetic nanoparticles

    Science.gov (United States)

    Witte, Kerstin; Müller, Knut; Grüttner, Cordula; Westphal, Fritz; Johansson, Christer

    2017-04-01

    Small magnetic nanoparticles with a narrow size distribution are of great interest for several biomedical applications. When the size of the particles decreases, the magnetic moment of the particles decreases. This leads to a significant increase in the separation time by several orders of magnitude. Therefore, in the present study the separation processes of bionized nanoferrites (BNF) with different sizes and concentrations were investigated with the commercial Sepmag Q system. It was found that an increasing initial particle concentration leads to a reduction of the separation time for large nanoparticles due to the higher probability of building chains. Small nanoparticles showed exactly the opposite behavior with rising particle concentration up to 0.1 mg(Fe)/ml. For higher iron concentrations the separation time remains constant and the measured Z-average decreases in the supernatant at same time intervals. At half separation time a high yield with decreasing hydrodynamic diameter of particles can be obtained using higher initial particle concentrations.

  7. Beaming of particles and synchrotron radiation in relativistic magnetic reconnection

    CERN Document Server

    Kagan, Daniel; Piran, Tsvi

    2016-01-01

    Relativistic reconnection has been invoked as a mechanism for particle acceleration in numerous astrophysical systems. According to idealised analytical models reconnection produces a bulk relativistic outflow emerging from the reconnection sites (X-points). The resulting radiation is therefore highly beamed. Using two-dimensional particle-in-cell (PIC) simulations, we investigate particle and radiation beaming, finding a very different picture. Instead of having a relativistic average bulk motion with isotropic electron velocity distribution in its rest frame, we find that the bulk motion of particles in X-points is similar to their Lorentz factor gamma, and the particles are beamed within about 5/gamma. On the way from the X-point to the magnetic islands, particles turn in the magnetic field, forming a fan confined to the current sheet. Once they reach the islands they isotropise after completing a full Larmor gyration and their radiation is not strongly beamed anymore. The radiation pattern at a given freq...

  8. Quantitative screening of yeast surface-displayed polypeptide libraries by magnetic bead capture.

    Science.gov (United States)

    Yeung, Yik A; Wittrup, K Dane

    2002-01-01

    Magnetic bead capture is demonstrated here to be a feasible alternative for quantitative screening of favorable mutants from a cell-displayed polypeptide library. Flow cytometric sorting with fluorescent probes has been employed previously for high throughput screening for either novel binders or improved mutants. However, many laboratories do not have ready access to this technology as a result of the limited availability and high cost of cytometers, restricting the use of cell-displayed libraries. Using streptavidin-coated magnetic beads and biotinylated ligands, an alternative approach to cell-based library screening for improved mutants was developed. Magnetic bead capture probability of labeled cells is shown to be closely correlated with the surface ligand density. A single-pass enrichment ratio of 9400 +/- 1800-fold, at the expense of 85 +/- 6% binder losses, is achieved from screening a library that contains one antibody-displaying cell (binder) in 1.1 x 10(5) nondisplaying cells. Additionally, kinetic screening for an initial high affinity to low affinity (7.7-fold lower) mutant ratio of 1:95,000, the magnetic bead capture method attains a single-pass enrichment ratio of 600 +/- 200-fold with a 75 +/- 24% probability of loss for the higher affinity mutant. The observed high loss probabilities can be straightforwardly compensated for by library oversampling, given the inherently parallel nature of the screen. Overall, these results demonstrate that magnetic beads are capable of quantitatively screening for novel binders and improved mutants. The described methods are directly analogous to procedures in common use for phage display and should lower the barriers to entry for use of cell surface display libraries.

  9. Immunogenic Subviral Particles Displaying Domain III of Dengue 2 Envelope Protein Vectored by Measles Virus

    Directory of Open Access Journals (Sweden)

    Indira S. Harahap-Carrillo

    2015-07-01

    Full Text Available Vaccines against dengue virus (DV are commercially nonexistent. A subunit vaccination strategy may be of value, especially if a safe viral vector acts as biologically active adjuvant. In this paper, we focus on an immunoglobulin-like, independently folded domain III (DIII from DV 2 envelope protein (E, which contains epitopes that elicits highly specific neutralizing antibodies. We modified the hepatitis B small surface antigen (HBsAg, S in order to display DV 2 DIII on a virus-like particle (VLP, thus generating the hybrid antigen DIII-S. Two varieties of measles virus (MV vectors were developed to express DIII-S. The first expresses the hybrid antigen from an additional transcription unit (ATU and the second additionally expresses HBsAg from a separate ATU. We found that this second MV vectoring the hybrid VLPs displaying DIII-S on an unmodified HBsAg scaffold were immunogenic in MV-susceptible mice (HuCD46Ge-IFNarko, eliciting robust neutralizing responses (averages against MV (1:1280 NT90, hepatitis B virus (787 mIU/mL, and DV2 (1:160 NT50 in all of the tested animals. Conversely, the MV vector expressing only DIII-S induced immunity against MV alone. In summary, DV2 neutralizing responses can be generated by displaying E DIII on a scaffold of HBsAg-based VLPs, vectored by MV.

  10. Proposal to Search for Magnetically Charged Particles with Magnetic Charge 1e

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, Michael K. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Fryberger, David [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-11-02

    A model for composite elementary Standard Model (SM) particles based upon magnetically bound vorton pairs, we briefly introduce here, predicts the existence of a complete family of magnetically charged particles, as well as their neutral isotopic partners (all counterparts to the SM elementary particles), in which the lowest mass (charged) particle would be an electrically neutral stable lepton, but which carries a magnetic charge equivalent to 1e. This new particle, which we call a magneticon (a counterpart to the electron) would be pair produced at all e+e- colliders at an Ecm above twice its mass. In addition, PP and PPbar colliders should also be able to produce these new particles through the Drell-Yan process. To our knowledge, no monopole search experiment has been sensitive to such a low-charged magnetic monopole above a particle mass of about 5 GeV/c2. Hence, we propose that a search for such a stable particle of magnetic charge 1e should be undertaken. We have taken the ATLAS detector at the LHC as an example in which this search might be done. To this end, we modeled the magnetic fields and muon trigger chambers of this detector. We show results from a simple Monte Carlo simulation program to indicate how these particles might look in the detector and describe how one might search for these new particles in the ATLAS data stream.

  11. Colloidal self assembly of non-magnetic particles in magnetic nanofluid

    Science.gov (United States)

    Jadav, Mudra; Patel, Rajesh

    2015-06-01

    Here we present a technique using magnetic nanofluid to induce bidispersed suspension of nonmagnetic particles to assemble into colloidal chain, triangle, rectangle, ring-flower configurations. By changing the amplitude and direction of the magnetic field, we could tune the structure of nonmagnetic particles in magnetic nanofluid. The structures are assembled using magneto static interactions between effectively nonmagnetic particles dispersed in magnetizable magnetic nanofluid. The assembly of complex structures out of simple colloidal building blocks is of practical interest in photonic crystals and DNA biosensors.

  12. Colloidal self assembly of non-magnetic particles in magnetic nanofluid

    Energy Technology Data Exchange (ETDEWEB)

    Jadav, Mudra; Patel, Rajesh, E-mail: rjp@mkbhavuni.edu.in, E-mail: rpat7@yahoo.co [Department of Physics, Maharaja Krishnakumarsinhji Bhavnagar University, Bhavnagar-364002 (India)

    2015-06-24

    Here we present a technique using magnetic nanofluid to induce bidispersed suspension of nonmagnetic particles to assemble into colloidal chain, triangle, rectangle, ring-flower configurations. By changing the amplitude and direction of the magnetic field, we could tune the structure of nonmagnetic particles in magnetic nanofluid. The structures are assembled using magneto static interactions between effectively nonmagnetic particles dispersed in magnetizable magnetic nanofluid. The assembly of complex structures out of simple colloidal building blocks is of practical interest in photonic crystals and DNA biosensors.

  13. Noncommutative magnetic moment of charged particles

    CERN Document Server

    Adorno, T C; Shabad, A E; Vassilevich, D V

    2011-01-01

    It has been argued, that in noncommutative field theories sizes of physical objects cannot be taken smaller than an elementary length related to noncommutativity parameters. By gauge-covariantly extending field equations of noncommutative U(1)_*-theory to the presence of external sources, we find electric and magnetic fields produces by an extended charge. We find that such a charge, apart from being an ordinary electric monopole, is also a magnetic dipole. By writing off the existing experimental clearance in the value of the lepton magnetic moments for the present effect, we get the bound on noncommutativity at the level of 10^4 TeV.

  14. Rotating magnetic field induced oscillation of magnetic particles for in vivo mechanical destruction of malignant glioma.

    Science.gov (United States)

    Cheng, Yu; Muroski, Megan E; Petit, Dorothée C M C; Mansell, Rhodri; Vemulkar, Tarun; Morshed, Ramin A; Han, Yu; Balyasnikova, Irina V; Horbinski, Craig M; Huang, Xinlei; Zhang, Lingjiao; Cowburn, Russell P; Lesniak, Maciej S

    2016-02-10

    Magnetic particles that can be precisely controlled under a magnetic field and transduce energy from the applied field open the way for innovative cancer treatment. Although these particles represent an area of active development for drug delivery and magnetic hyperthermia, the in vivo anti-tumor effect under a low-frequency magnetic field using magnetic particles has not yet been demonstrated. To-date, induced cancer cell death via the oscillation of nanoparticles under a low-frequency magnetic field has only been observed in vitro. In this report, we demonstrate the successful use of spin-vortex, disk-shaped permalloy magnetic particles in a low-frequency, rotating magnetic field for the in vitro and in vivo destruction of glioma cells. The internalized nanomagnets align themselves to the plane of the rotating magnetic field, creating a strong mechanical force which damages the cancer cell structure inducing programmed cell death. In vivo, the magnetic field treatment successfully reduces brain tumor size and increases the survival rate of mice bearing intracranial glioma xenografts, without adverse side effects. This study demonstrates a novel approach of controlling magnetic particles for treating malignant glioma that should be applicable to treat a wide range of cancers.

  15. Particle size dependent rheological property in magnetic fluid

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jie; Pei, Lei; Xuan, Shouhu, E-mail: xuansh@ustc.edu.cn; Yan, Qifan; Gong, Xinglong, E-mail: gongxl@ustc.edu.cn

    2016-06-15

    The influence of the particle size on the rheological property of magnetic fluid was studied both by the experimental and computer simulation methods. Firstly, the magnetic fluids were prepared by dispersing Fe{sub 3}O{sub 4} nanospheres with size varied from 40 nm to 100 nm and 200 nm in the solution. Then, the rheological properties were investigated and it was found that the relative magnetorheological effects increased with increasing the particle size. Finally, the molecular dynamic simulation was used to analyze the mechanical characteristics of the magnetic fluid and the chain-like model agreed well with the experimental result. The authentic chain-like structure observed by a microscope agreed with the simulation results. The three particles composed of the similar cluster nanostructure, thus they exhibited similar magnetic property. To this end, the unique assembling microstructures was the origination of the mechanical difference. And it was found that the higher MR (magnetorheological) effects of the large particle based magnetic fluid was originated from the stronger assembling microstructure under the applying magnetic field. - Highlights: • 40 nm, 100 nm and 200 nm Fe{sub 3}O{sub 4} nanospheres were dispersed in water. • The magnetorheological effect increased with increasing the particle sizes. • Molecular dynamic simulation was used in this article.

  16. On magnetic guidance of charged particles

    Science.gov (United States)

    Backe, H.

    2016-04-01

    High precision beta decay experiments with polarized neutrons, employing magnetic guiding fields for the decay electrons in combination with energy dispersive detectors, initiated detailed studies of the point spread function (PSF) for homogeneous magnetic fields. A PSF describes the radial probability distribution of mono-energetic electrons at the detector plane which were emitted from a point-like source. With regard to accuracy considerations for high-precision experiments unwanted singularities occur as function of the radial detector coordinate which have recently been discussed in detail by Dubbers (2015) [3]. In the present article mathematical inconsistencies in the approximations to calculate PSFs have been corrected. In addition, numerical orbit calculations have been performed for inhomogeneous magnetic fields which show that, on the one hand, generalizations on the basis of adiabaticity considerations must be handled with care but indicate, on the other hand, that non-adiabaticity would not prevent a proposed check of magnetic field configurations.

  17. Properties of magnetic nano-particles

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1997-01-01

    The intrinsic thermodynamic magnetic properties of clusters are discussed using spin wave theory for a Heisenberg model, with a fixed magnitude of the spins S-i = S and site independent nearest neighbor exchange interaction. The consequences of the more realistic Hubbard model is considered...... in which we allow for a magnetization profile at T = 0 and a structural relaxation, which in turn will give rise to a site dependent exchange interaction. Et is concluded that correlation effects among the electrons play a very important role in small clusters, albeit not modifying the thermodynamic...... properties drastically. The finite cluster size gives foremost rise to a discrete excitation spectrum with a large energy gap to the ground state. The relaxation of the magnetization during the reversal of the external magnetic field is discussed. A first step towards a quantitative understanding...

  18. Protein purification using magnetic adsorbent particles

    DEFF Research Database (Denmark)

    Franzreb, M; Siemann-Herzberg, M.; Hobley, Timothy John

    2006-01-01

    separations are fast, gentle, scaleable, easily automated, can achieve separations that would be impossible or impractical to achieve by other techniques, and have demonstrated credibility in a wide range of disciplines, including minerals processing, wastewater treatment, molecular biology, cell sorting...... and clinical diagnostics. However, despite the highly attractive qualities of magnetic methods on a process scale, with the exception of wastewater treatment, few attempts to scale up magnetic operations in biotechnology have been reported thus far. The purpose of this review is to summarise the current state...... of other suspended solids. Thus, it becomes possible to magnetically separate selected target species directly out of crude biological process liquors (e.g. fermentation broths, cell disruptates, plasma, milk, whey and plant extracts) simply by binding them on magnetic adsorbents before application...

  19. Using pot-magnets to enable stable and scalable electromagnetic tactile displays.

    Science.gov (United States)

    Zarate, Juan; Shea, Herbert

    2016-07-19

    We present the design, fabrication, characterization and psychophysical testing of a scalable haptic display based on electromagnetic (EM) actuators. The display consists of a 4x4 array of taxels, each of which can be in a raised or a lowered position, thus generating different static configurations. One of the most challenging aspects when designing densely-packed arrays of EM actuators is obtaining large actuation forces while simultaneously generating only weak interactions between neighboring taxels. In this work we introduce a lightweight and effective magnetic shielding architecture. The moving part of each taxel is a cylindrical permanent magnet embedded in a ferromagnetic pot, forming a pot-magnet. An array of planar microcoils attracts or repels each pot-magnet. This configuration reduces the interaction between neighboring magnets by more than one order of magnitude, while the coil/magnet interaction is only reduced by 10%. For 4 mm diameter pins on an 8 mm pitch, we obtained displacements of 0.55 mm and forces of 40 mN using 1.7 W. We measured the accuracy of human perception under two actuation configurations which differed in the force vs. displacement curve. We obtained 91% of correct answers in pulling configuration and 100% in pushing configuration.

  20. Synthesis and Manipulation of Biofunctional Magnetic Particles

    Science.gov (United States)

    2007-06-18

    membrane . 2. Uses of Maqnetic Interactions in Biochemistry and Biophysics. * High-Field Concentrators. One of the key components to magnetic...nucleus and on the surface membrane at the opposite pole of the cell. 0 Electromagnetic needles with submicron pole tip radii for nanomanipulation of...of MicroElectroMechanical Systems". Provisional filed 9/21/04- abandoned. Case 1950 abandoned - title: "Fabrication of Magnetic Microfiltration

  1. Very high coercivity magnetic stripes produced by particle rotation

    Energy Technology Data Exchange (ETDEWEB)

    Naylor, R.B.

    1992-12-01

    This paper describes a current research program at Sandia National Laboratories whereby magnetic stripes are produced through the use of a new particle rotation technology. This new process allows the stripes to be produced in bulk and then held in a latent state so that they may be encoded at a later date. Since particle rotation is less dependent on the type of magnetic particle used, very high coercivity particles could provide a way to increase both magnetic tamper-resistance and accidental erasure protection. This research was initially funded by the Department of Energy, Office of Safeguard and Security as a portion of their Science and Technology Base Development, Advanced Security Concepts program. Current program funding is being provided by Sandia National Laboratories as part of their Laboratory Directed Research and Development program.

  2. Magnetic resonance imaging by using nano-magnetic particles

    Energy Technology Data Exchange (ETDEWEB)

    Shokrollahi, H., E-mail: Shokrollahi@sutech.ac.ir [Electroceramics Group, Department of Materials Science and Engineering, Shiraz University of Technology, Shiraz (Iran, Islamic Republic of); Khorramdin, A. [Electroceramics Group, Department of Materials Science and Engineering, Shiraz University of Technology, Shiraz (Iran, Islamic Republic of); Isapour, Gh. [Department of Materials and Engineering, Hakim Sabzevari University (Iran, Islamic Republic of)

    2014-11-15

    Magnetism and magnetic materials play a major role in various biological applications, such as magnetic bioseparation, magnetic resonance imaging (MRI), hyperthermia treatment of cancer and drug delivery. Among these techniques, MRI is a powerful method not only for diagnostic radiology but also for therapeutic medicine that utilizes a magnetic field and radio waves. Recently, this technique has contributed greatly to the promotion of the human quality life. Thus, this paper presents a short review of the physical principles and recent advances of MRI, as well as providing a summary of the synthesis methods and properties of contrast agents, like different core materials and surfactants. - Highlights: • This paper studies the physics of MRI as a powerful diagnostic technique. • MRI uses the differentiation between healthy and pathological tissues. • The relaxation times can be shortened by the use of a magnetic contrast agent. • The magnetic nanoparticles act as contrast agents, helping to increase the resolution. • Different synthesis methods can influence the magnetic resonance behavior.

  3. Influence of Magnetic Field Amplitude on Quantity and Sizes of Disintegration Fragments of Magnetic Particles Cluster

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The disintegration of a mass of magnetic particles is investigated at pulsing switching on a magnetic field. The influence of field value on quantity, sizes and allocation of fragments of disintegration is explored. The presence of two critical fields, defining the process of disintegration, is revealed. The results can be used at manufacture of packings to magnetic filters.

  4. Switchable Magnetic Bottles and Field Gradients for Particle Traps

    CERN Document Server

    Vogel, Manuel; Quint, Wolfgang; von Lindenfels, David; Wiesel, Marco

    2014-01-01

    Versatile methods for the manipulation of individual quantum systems, such as confined particles, have become central elements in current developments in precision spectroscopy, frequency standards, quantum information processing, quantum simulation, and alike. For atomic and some subatomic particles, both neutral and charged, a precise control of magnetic fields is essen- tial. In this paper, we discuss possibilities for the creation of specific magnetic field configurations which find appli- cation in these areas. In particular, we pursue the idea of a magnetic bottle which can be switched on and off by transition between the normal and the superconducting phase of a suitable material in cryogenic environments, for example in trap experiments in moderate magnetic fields. Methods for a fine-tuning of the magnetic field and its linear and quadratic components in a trap are presented together with possible applications.

  5. Magnetic field flow phenomena in a falling particle receiver

    Science.gov (United States)

    Armijo, Kenneth M.; Ho, Clifford; Anderson, Ryan; Christian, Joshua; Babiniec, Sean; Ortega, Jesus

    2016-05-01

    Concentrating solar power (CSP) falling particle receivers are being pursued as a desired means for utilizing low-cost, high-absorptance particulate materials that can withstand high concentration ratios (˜1000 suns), operating temperatures above 700 °C, and inherent storage capabilities which can be used to reduce to levelized cost of electricity (LCOE)1. Although previous falling particle receiver designs have proven outlet temperatures above 800 °C, and thermal efficiencies between 80-90%, performance challenges still exist to operate at higher concentration ratios above 1000 suns and greater solar absorptance levels. To increase absorptance, these receivers will require enhanced particle residence time within a concentrated beam of sunlight. Direct absorption solid particle receivers that can enhance this residence time will have the potential to achieve heat-transfer media temperatures2 over 1000 °C. However, depending on particle size and external forces (e.g., external wind and flow due to convective heat losses), optimized particle flow can be severely affected, which can reduce receiver efficiency. To reduce particle flow destabilization and increase particle residence time on the receiver an imposed magnetic field is proposed based on a collimated design for two different methodologies. These include systems with ferromagnetic and charged particle materials. The approaches will be analytically evaluated based on magnetic field strength, geometry, and particle parameters, such as magnetic moment. A model is developed using the computational fluid dynamics (CFD) code ANSYS FLUENT to analyze these approaches for a ˜2 MWth falling particle receiver at Sandia National Laboratories5,6. Here, assessment will be made with respect to ferromagnetic particles such as iron-oxides, as well as charged particles. These materials will be parametrically assessed (e.g., type, size, dipole moment and geometry) over a range of magnetic permeability, μ values. Modeling

  6. Energetic particle transport across the mean magnetic field: before diffusion

    CERN Document Server

    Laitinen, T

    2016-01-01

    Current particle transport models describe the propagation of charged particles across the mean field direction in turbulent plasmas as diffusion. However, recent studies suggest that at short time-scales, such as soon after solar energetic particle (SEP) injection, particles remain on turbulently meandering field lines, which results in non-diffusive initial propagation across the mean magnetic field. In this work, we use a new technique to investigate how the particles are displaced from their original field lines, and quantify the parameters of the transition from field-aligned particle propagation along meandering field lines to particle diffusion across the mean magnetic field. We show that the initial decoupling of the particles from the field lines is slow, and particles remain within a Larmor radius from their initial meandering field lines for tens to hundreds of Larmor periods, for 0.1-10 MeV protons in turbulence conditions typical of the solar wind at 1~AU. Subsequently, particles decouple from th...

  7. Statistical analysis of magnetically soft particles in magnetorheological elastomers

    Science.gov (United States)

    Gundermann, T.; Cremer, P.; Löwen, H.; Menzel, A. M.; Odenbach, S.

    2017-04-01

    The physical properties of magnetorheological elastomers (MRE) are a complex issue and can be influenced and controlled in many ways, e.g. by applying a magnetic field, by external mechanical stimuli, or by an electric potential. In general, the response of MRE materials to these stimuli is crucially dependent on the distribution of the magnetic particles inside the elastomer. Specific knowledge of the interactions between particles or particle clusters is of high relevance for understanding the macroscopic rheological properties and provides an important input for theoretical calculations. In order to gain a better insight into the correlation between the macroscopic effects and microstructure and to generate a database for theoretical analysis, x-ray micro-computed tomography (X-μCT) investigations as a base for a statistical analysis of the particle configurations were carried out. Different MREs with quantities of 2–15 wt% (0.27–2.3 vol%) of iron powder and different allocations of the particles inside the matrix were prepared. The X-μCT results were edited by an image processing software regarding the geometrical properties of the particles with and without the influence of an external magnetic field. Pair correlation functions for the positions of the particles inside the elastomer were calculated to statistically characterize the distributions of the particles in the samples.

  8. Arrangement at the nanoscale: Effect on magnetic particle hyperthermia

    Science.gov (United States)

    Myrovali, E.; Maniotis, N.; Makridis, A.; Terzopoulou, A.; Ntomprougkidis, V.; Simeonidis, K.; Sakellari, D.; Kalogirou, O.; Samaras, T.; Salikhov, R.; Spasova, M.; Farle, M.; Wiedwald, U.; Angelakeris, M.

    2016-11-01

    In this work, we present the arrangement of Fe3O4 magnetic nanoparticles into 3D linear chains and its effect on magnetic particle hyperthermia efficiency. The alignment has been performed under a 40 mT magnetic field in an agarose gel matrix. Two different sizes of magnetite nanoparticles, 10 and 40 nm, have been examined, exhibiting room temperature superparamagnetic and ferromagnetic behavior, in terms of DC magnetic field, respectively. The chain formation is experimentally visualized by scanning electron microscopy images. A molecular Dynamics anisotropic diffusion model that outlines the role of intrinsic particle properties and inter-particle distances on dipolar interactions has been used to simulate the chain formation process. The anisotropic character of the aligned samples is also reflected to ferromagnetic resonance and static magnetometry measurements. Compared to the non-aligned samples, magnetically aligned ones present enhanced heating efficiency increasing specific loss power value by a factor of two. Dipolar interactions are responsible for the chain formation of controllable density and thickness inducing shape anisotropy, which in turn enhances magnetic particle hyperthermia efficiency.

  9. Radiolysis and hydrolysis of magnetically assisted chemical separation particles

    Energy Technology Data Exchange (ETDEWEB)

    Buchholz, B.A.; Nunez, L.; Vandegrift, G.F.

    1995-05-01

    The magnetically assisted chemical separation (MACS) process is designed to separate transuranic (TRU) elements out of high-level waste (HLW) or TRU waste. Magnetic microparticles (1--25 {mu}m) were coated with octyl (phenyl)N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) dissolved in tributyl phosphate (TBP) and tested for removing TRU elements from acidic nitrate solutions. The particles were contacted with nitric acid solutions and Hanford plutonium finishing plant (PFP) simulant, irradiated with a high intensity {sup 60}Co {gamma}-ray source, and evaluated for effectiveness in removing TRU elements from 2m HNO{sub 3} solutions. The resistance of the coatings and magnetic cores to radiolytic damage and hydrolytic degradation was investigated by irradiating samples of particles suspended in a variety of solutions with doses of up to 5 Mrad. Transmission electron microscopy (TEM), magnetic susceptibility measurements, and physical observations of the particles and suspension solutions were used to assess physical changes to the particles. Processes that affect the surface of the particles dramatically alter the binding sites for TRU in solution. Hydrolysis played a larger role than radiolysis in the degradation of the extraction capacity of the particles.

  10. Solar energetic particle propagation in 3-dimensional heliospheric magnetic field

    Science.gov (United States)

    Zhang, M.; Qin, G.; Rassoul, H.

    2008-05-01

    We present the first model calculation of solar energetic particle propagation in realistic 3-dimensional heliopsheric magnetic field. The model includes essentially all the particle transport mechanisms: streaming along magnetic fields, convection with the solar wind, pitch-angle diffusion, focusing, perpendicular diffusion, and pitch-angle dependent adiabatic cooling. We solve the Fokker-Planck transport equation with simulation of backward stochastic processes in a fixed reference frame. Here we focus on high-energy E > ~ 10 MeV solar energetic particles that are accelerated and injected near the Sun. The source of solar energetic particles can be either solar flares or coronal mass ejections, both having limited coverage of latitude and longitude on the solar surface. We compute the particle flux and anisotropy profiles at various observation locations in interplanetary space up to 5 AU from the ecliptic to the solar poles. We found that solar energetic particles are observed no matter whether an observer is directly connected to solar source by the magnetic field. Our model calculation results can explain why we often see solar energetic particles reach an almost uniform reservoir in the inner heliosphere a few days after the onset of a solar energetic particle event and then the intensities of particles in a broad range of energies decay uniformly everywhere. This phenomenon can happen without a need of particle diffusion barrier in the outer heliosphere. We will discuss what mechanism is responsible for the formation of such a reservoir and what role the perpendicular diffusion plays in the transport of solar energetic particles.

  11. Full particle orbit effects in regular and stochastic magnetic fields

    CERN Document Server

    Ogawa, Shun; Leoncini, Xavier; Vittot, Michel; del Castillo-Negrete, Diego; Dif-Pradalier, Guilhem; Garbet, Xavier

    2016-01-01

    We study numerically the motion of a charged particle evolving in a periodic cylindric static magnetic field, in order to investigate a magnetic model of internal transport barrier (ITB). Starting from an initial ideal configuration with a given q-profile, we perturb the magnetic structure by adding first only one mode, and then two modes. In the first two considered cases magnetic field lines are integrable, while they become chaotic when two modes are present. Regarding the particle motion, while it is integrable in the ideal configuration, we show that generic chaotic motion arises as soon as one of the magnetic mode is present. Given the presence of two conserved quantities, the existence of chaos in phase space implies that a conserved quantity related to the magnetic moment cannot exist globally in phase space. Regarding the motion when two modes are present and magnetic field lines are chaotic, the particles trajectory analysis indicates that the regions where chaotic motion occurs decreases as the ene...

  12. Exploring multifunctional potential of commercial ferrofluids by magnetic particle hyperthermia

    Energy Technology Data Exchange (ETDEWEB)

    Sakellari, Despoina, E-mail: dsakel@physics.auth.gr; Mathioudaki, Stella; Kalpaxidou, Zoi; Simeonidis, Konstantinos; Angelakeris, Makis

    2015-04-15

    In this work we examine a selection of commercially available magnetic iron oxide nanoparticles as candidates for magnetic particle hyperthermia applications combining their primary modality with additional heat triggered actions. Contrary to lab-made magnetic nanoparticles, commercial ferrofluids may be rapidly pushed through the medical approval processes since their applicability has already been addressed successfully (i.e., formulation, reproducibility, toxicity and quality assurance) in conjunction with the strong companies′ drive in the fast delivery of the new therapy to the patient. Four samples are under study with variable hydrodynamic diameters from two companies (Micromod and Chemicell) consisting of iron-oxide magnetic nanoparticles. The tunable magnetic heating characteristics of the ferrofluids were correlated with particle, field and colloidal solution features. Our work revealed a size-dependent magnetic heating efficiency together with fast thermal response, features that are crucial for adequate thermal efficiency combined with minimum treatment duration and show the potential of such materials as multifunctional theranostic agents. - Highlights: • Commercial ferrofluids were examined as magnetic particle hyperthermia candidates. • Results show an enhanced heating efficiency. • Heating efficiency can be tuned by field amplitude and hydrodynamic size of NPs. • Coating material seems to be a key parameter for the optimum thermal response.

  13. Synthesis, structural and magnetic characterization of soft magnetic nanocrystalline ternary FeNiCo particles

    Science.gov (United States)

    Toparli, Cigdem; Ebin, Burçak; Gürmen, Sebahattin

    2017-02-01

    The present study focuses on the synthesis, microstructural and magnetic properties of ternary FeNiCo nanoparticles. Nanocrystalline ternary FeNiCo particles were synthesized via hydrogen reduction assisted ultrasonic spray pyrolysis method in single step. The effect of precursor concentration on the morphology and the size of particles was investigated. The syntheses were performed at 800 °C. Structure, morphology and magnetic properties of the as-prepared products were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) studies. Scherer calculation revealed that crystallite size of the ternary particles ranged between 36 and 60 nm. SEM and TEM investigations showed that the particle size was strongly influenced by the precursor concentration and Fe, Ni, Co elemental composition of individual particles was homogeneous. Finally, the soft magnetic properties of the particles were observed to be a function of their size.

  14. Particle energization in a chaotic force-free magnetic field

    Science.gov (United States)

    Li, Xiaocan; Li, Gang; Dasgupta, Brahmananda

    2015-04-01

    A force-free field (FFF) is believed to be a reasonable description of the solar corona and in general a good approximation for low-beta plasma. The equations describing the magnetic field of FFF is similar to the ABC fluid equations which has been demonstrated to be chaotic. This implies that charged particles will experience chaotic magnetic field in the corona. Here, we study particle energization in a time-dependent FFF using a test particle approach. An inductive electric field is introduced by turbulent motions of plasma parcels. We find efficient particle acceleration with power-law like particle energy spectra. The power-law indices depend on the amplitude of plasma parcel velocity field and the spatial scales of the magnetic field fluctuation. The spectra are similar for different particle species. This model provide a possible mechanism for seed population generation for particle acceleration by, e.g., CME-driven shocks. Generalization of our results to certain non-force-free-field (NFFF) is straightforward as the sum of two or multiple FFFs naturally yield NFFF.

  15. FIRST-ORDER PARTICLE ACCELERATION IN MAGNETICALLY DRIVEN FLOWS

    Energy Technology Data Exchange (ETDEWEB)

    Beresnyak, Andrey [Naval Research Laboratory, Washington, DC 20375 (United States); Li, Hui [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2016-03-10

    We demonstrate that particles are regularly accelerated while experiencing curvature drift in flows driven by magnetic tension. Some examples of such flows include spontaneous turbulent reconnection and decaying magnetohydrodynamic turbulence, where a magnetic field relaxes to a lower-energy configuration and transfers part of its energy to kinetic motions of the fluid. We show that this energy transfer, which normally causes turbulent cascade and heating of the fluid, also results in a first-order acceleration of non-thermal particles. Since it is generic, this acceleration mechanism is likely to play a role in the production of non-thermal particle distribution in magnetically dominant environments such as the solar chromosphere, pulsar magnetospheres, jets from supermassive black holes, and γ-ray bursts.

  16. Rotating magnetic particle microrheometry in biopolymer fluid dynamics: mucus microrheology.

    Science.gov (United States)

    Besseris, George J; Yeates, Donovan B

    2007-09-14

    The polymer properties of canine mucus were investigated through the method of rotating magnetic particle microrheometry. Mucus is visualized as a physically entangled biopolymer of low polydispersity in a water-based solution. Mucus was modeled according to the constitutive law of a Doi-Edwards fluid. The magnetic-particle equation of rotational motion is analytically solved in the linear viscoelastic limit rendering theoretical flow profiles which are used to fit the experimental trace signals of the particle remanent-magnetic-field decay. The zero-shear-rate viscosity was found to be 18,000 P and the relaxation time at about 42 s. The molecular weight between entanglements for mucins was estimated at 1.7 MDa rendering an estimation of about seven physical cross-links per molecule. Rheological investigations were extended also to diluted and concentrated rations of the normal mucus simulating the conditions found in more physiological extremes.

  17. Biohazard Detoxification Method Utilizing Magnetic Particles

    Science.gov (United States)

    2007-05-01

    extracorporeal blood circulation and cardiocirculatory bypass," Int. J. Artif . Organs. 25, 297-305 (2002). 23M.C. Yang and C.C. Lin, "In vitro...would bind to blood -borne toxins due to selective receptors attached to the nanosphere surface. After circulation, a suitable artery or vein is accessed...with a small, hand held magnetic filter unit. The blood is purified of the toxin-loaded nanospheres within the unit and the clean blood is returned

  18. Effective magnetization of the dust particles in a complex plasma

    Science.gov (United States)

    Kählert, Hanno

    2012-10-01

    The large mass and size of the dust particles in a complex plasma has several advantages, including low characteristic frequencies on the order of a few Hz and the ability to record their motion with video cameras. However, these properties pose major difficulties for achieving strong magnetization. While the light electrons and ions can be magnetized by (superconducting) magnets, magnetizing the heavy dust component is extremely challenging. Instead of further increasing the magnetic field strengths or decreasing the particle size, we use the analogy between the Lorentz force and the Coriolis force experienced by particles in a rotating reference frame to create ``effective magnetic fields'' which is a well-established technique in the field of trapped quantum gases [1]. To induce rotation in a complex plasma, we take advantage of the neutral drag force, which allows to transmit the motion of a rotating neutral gas to the dust particles [2]. The equations of motion in the rotating frame agree with those in a stationary gas except for the additional centrifugal and Coriolis forces [3]. Due to the slow rotation frequencies (˜ Hz) and contrary to the situation in a strong magnetic field, only the properties of the heavy dust particles are notably affected. Experiments with a rotating electrode realize the desired velocity profile for the neutral gas and allow us to verify the efficiency of the concept [3].[4pt] This work was performed in collaboration with J. Carstensen, M. Bonitz, H. L"owen, F. Greiner, and A. Piel.[4pt] [1] A. L. Fetter, Rev. Mod. Phys. 81, 647 (2009)[0pt] [2] J. Carstensen, F. Greiner, L.-J. Hou, H. Maurer, and A. Piel, Phys. Plasmas 16, 013702 (2009)[0pt] [3] H. K"ahlert, J. Carstensen, M. Bonitz, H. L"owen, F. Greiner, and A. Piel, submitted for publication, arXiv:1206.5073

  19. Magnetic properties of iron particles embedded in multiwall carbon nanotubes.

    Science.gov (United States)

    Arya, Ved Prakash; Prasad, V; Kumar, P S Anil

    2009-09-01

    Iron nanoparticles are embedded in multiwall carbon nanotubes by the chemical vapor deposition, where benzene and ferrocene are taken as precursor materials. Varying quantity of iron particles are embedded in these tubes by taking different amount of ferrocene. These particles exhibit a magnetic moment up to 98 emu/g and an enhanced coercivity in the range of 500-2000 Oe. Negative magnetoresistance approximately 10% is observed in the presence of magnetic field up to 11 T applied at various temperatures in the range of 1.3 K-300 K. It is argued that the enhanced coercivity is due to the shape anisotropy. The negative magnetoresistance is believed to be due to the weak localization and spin dependent scattering of electrons by the ferromagnetic particles. In addition we also observe a dependence of the magnetoresistance on the direction of applied field and this is correlated with the shape anisotropy of the Fe particles.

  20. Extreme Particle Acceleration via Magnetic Reconnection in the Crab Nebula

    Science.gov (United States)

    Cerutti, Benoit; Uzdensky, D. A.; Begelman, M. C.

    2012-01-01

    The discovery by Agile and Fermi of intense day-long synchrotron gamma-ray flares above 100 MeV in the Crab Nebula challenges classical models of pulsar wind nebulae and particle acceleration. We argue that the flares are powered by magnetic reconnection in the nebula. Using relativistic test-particle simulations, we show that particles are naturally focused into a thin fan beam, deep inside the reconnection layer where the magnetic field is small. The particles then suffer less from synchrotron losses and pile up at the maximum energy given by the electric potential drop in the layer. Applying this model to the Crab Nebula, we find that the emerging synchrotron emission spectrum above 100 MeV is consistent with the September 2010 flare observations. No detectable emission is expected at other wavelengths. This scenario provides a viable explanation for the Crab Nebula gamma-ray flares.

  1. Small oscillations of two interacting particles in a magnetic field

    Science.gov (United States)

    del Pino, L. A.; Curilef, S.

    2016-11-01

    The classical behavior of two interacting particles in the presence of a uniform magnetic field is studied in the small oscillations approximation. Using the Lagrangian formalism, the equations of motion are derived, as are their solutions and constants of motion. Normal modes of oscillations and their corresponding normal coordinates are obtained that strongly depend on the initial condition; therefore, we observe that the oscillation along the line that joins the particles is non-isochronous. In addition, particular attention has been paid to the planar motion, without the pseudomomentum component parallel to the magnetic field, where one longitudinal mode and two transversal modes are obtained.

  2. Frequency Mixing Magnetic Detection Scanner for Imaging Magnetic Particles in Planar Samples.

    Science.gov (United States)

    Hong, Hyobong; Lim, Eul-Gyoon; Jeong, Jae-Chan; Chang, Jiho; Shin, Sung-Woong; Krause, Hans-Joachim

    2016-06-09

    The setup of a planar Frequency Mixing Magnetic Detection (p-FMMD) scanner for performing Magnetic Particles Imaging (MPI) of flat samples is presented. It consists of two magnetic measurement heads on both sides of the sample mounted on the legs of a u-shaped support. The sample is locally exposed to a magnetic excitation field consisting of two distinct frequencies, a stronger component at about 77 kHz and a weaker field at 61 Hz. The nonlinear magnetization characteristics of superparamagnetic particles give rise to the generation of intermodulation products. A selected sum-frequency component of the high and low frequency magnetic field incident on the magnetically nonlinear particles is recorded by a demodulation electronics. In contrast to a conventional MPI scanner, p-FMMD does not require the application of a strong magnetic field to the whole sample because mixing of the two frequencies occurs locally. Thus, the lateral dimensions of the sample are just limited by the scanning range and the supports. However, the sample height determines the spatial resolution. In the current setup it is limited to 2 mm. As examples, we present two 20 mm × 25 mm p-FMMD images acquired from samples with 1 µm diameter maghemite particles in silanol matrix and with 50 nm magnetite particles in aminosilane matrix. The results show that the novel MPI scanner can be applied for analysis of thin biological samples and for medical diagnostic purposes.

  3. Single-Particle Quantum Dynamics in a Magnetic Lattice

    Energy Technology Data Exchange (ETDEWEB)

    Venturini, Marco

    2001-02-01

    We study the quantum dynamics of a spinless charged-particle propagating through a magnetic lattice in a transport line or storage ring. Starting from the Klein-Gordon equation and by applying the paraxial approximation, we derive a Schroedinger-like equation for the betatron motion. A suitable unitary transformation reduces the problem to that of a simple harmonic oscillator. As a result we are able to find an explicit expression for the particle wavefunction.

  4. Controlling temperature in magnetic hyperthermia with low Curie temperature particles

    Science.gov (United States)

    Astefanoaei, Iordana; Dumitru, Ioan; Chiriac, Horia; Stancu, Alexandru

    2014-05-01

    Hyperthermia induced by the heating of magnetic particles (MPs) in alternating magnetic field receives a considerable attention in cancer therapy. An interesting development in the studies dedicated to magnetically based hyperthermia is the possibility to control the temperature using MPs with selective magnetic absorption properties. This paper analyzes the temperature field determined by the heating of MPs having low Curie temperature (a FeCrNbB particulate system) injected within a malignant tissue, subjected to an ac magnetic field. The temperature evolution within healthy and tumor tissues was analyzed by finite element method simulations in a thermo-fluid model. The cooling effect produced by blood flowing in blood vessels was considered. This effect is intensified at the increase of blood velocity. The FeCrNbB particles, having the Curie temperature close to the therapeutic range, transfer the heat more homogeneous in the tumor keeping the temperature within the therapeutic range in whole tumor volume. Having the possibility to automatically control the temperature within a tumor, these particle type opens new research horizons in the magnetic hyperthermia.

  5. Modeling of particles orientation in magnetic field in drying magnetic coatings

    Science.gov (United States)

    Potanin, Andrei A.; Reynolds, George; J. Hirko, Ronald

    2000-03-01

    Filament coating is studied as a model of magnetic tape manufacturing. Freshly coated filament is driven through a solenoid magnet which orients particles. After drying the coated filament, its squareness is measured as a function of the magnet position, field and the filament speed during coating. Production and model mixes are tested, which differ in dispersion quality and drying rate. A mean-field model is used to describe orientation of particles in the coating. The model fits experiments with two parameters: particles mobility and a mean-field interaction coefficient. Well dispersed kneaded mix has higher mobility and weaker interactions than non-kneaded mixes. The model well agrees with the data for squareness decay with magnet separation from the mix deposition point, thereby providing a theoretical tool for finding proper magnet position on the production coating lines.

  6. Simulation of magnetic hysteresis loops and magnetic Barkhausen noise of α-iron containing nonmagnetic particles

    Directory of Open Access Journals (Sweden)

    Yi Li

    2015-07-01

    Full Text Available The magnetic hysteresis loops and Barkhausen noise of a single α-iron with nonmagnetic particles are simulated to investigate into the magnetic hardening due to Cu-rich precipitates in irradiated reactor pressure vessel (RPV steels. Phase field method basing Landau-Lifshitz-Gilbert (LLG equation is used for this simulation. The results show that the presence of the nonmagnetic particle could result in magnetic hardening by making the nucleation of reversed domains difficult. The coercive field is found to increase, while the intensity of Barkhausen noise voltage is decreased when the nonmagnetic particle is introduced. Simulations demonstrate the impact of nucleation field of reversed domains on the magnetization reversal behavior and the magnetic properties.

  7. Simulation of magnetic hysteresis loops and magnetic Barkhausen noise of α-iron containing nonmagnetic particles

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yi; Li, Qiulin; Liu, Wei, E-mail: liuw@mail.tsinghua.edu.cn [School of Material Science and Engineering, Tsinghua University, Beijing, 100084 (China); Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055 (China); Xu, Ben [School of Material Science and Engineering, Tsinghua University, Beijing, 100084 (China); Hu, Shenyang; Li, Yulan [Energy Materials Division, Pacific Northwest National Laboratory, Richland, WA, 99352 (United States)

    2015-07-15

    The magnetic hysteresis loops and Barkhausen noise of a single α-iron with nonmagnetic particles are simulated to investigate into the magnetic hardening due to Cu-rich precipitates in irradiated reactor pressure vessel (RPV) steels. Phase field method basing Landau-Lifshitz-Gilbert (LLG) equation is used for this simulation. The results show that the presence of the nonmagnetic particle could result in magnetic hardening by making the nucleation of reversed domains difficult. The coercive field is found to increase, while the intensity of Barkhausen noise voltage is decreased when the nonmagnetic particle is introduced. Simulations demonstrate the impact of nucleation field of reversed domains on the magnetization reversal behavior and the magnetic properties.

  8. Particle trajectories in Weibel magnetic filaments with a flow-aligned magnetic field

    Science.gov (United States)

    Bret, Antoine

    2016-08-01

    > . In the absence of an external guiding magnetic field, these filaments can block the incoming flow, initiating the shock formation, if their size is larger than the Larmor radius of the incoming particles in the peak field. Here we show that this result still holds in the presence of an external magnetic field, provided it is not too high. Yet, for 0\\gtrsim Bf/2, the filaments become unable to stop any particle, regardless of its initial velocity.

  9. Physical properties of elongated magnetic particles: magnetization and friction coefficient anisotropies.

    Science.gov (United States)

    Vereda, Fernando; de Vicente, Juan; Hidalgo-Alvarez, Roque

    2009-06-02

    Anisotropy counts: A brief review of the main physical properties of elongated magnetic particles (EMPs) is presented. The most important characteristic of an EMP is the additional contribution of shape anisotropy to the total anisotropy energy of the particle, when compared to spherical magnetic particles. The electron micrograph shows Ni-ferrite microrods fabricated by the authors.We present an overview of the main physical properties of elongated magnetic particles (EMPs), including some of their more relevant properties in suspension. When compared to a spherical magnetic particle, the most important characteristic of an EMP is an additional contribution of shape anisotropy to the total anisotropy energy of the particle. Increasing aspect ratios also lead to an increase in both the critical single-domain size of a magnetic particle and its resistance to thermally activated spontaneous reversal of the magnetization. For single-domain EMPs, magnetization reversal occurs primarily by one of two modes, coherent rotation or curling, the latter being facilitated by larger aspect ratios. When EMPs are used to prepare colloidal suspensions, other physical properties come into play, such as their anisotropic friction coefficient and the consequent enhanced torque they experience in a shear flow, their tendency to align in the direction of an external field, to form less dense sediments and to entangle into more intricate aggregates. From a more practical point of view, EMPs are discussed in connection with two interesting types of magnetic colloids: magnetorheological fluids and suspensions for magnetic hyperthermia. Advances reported in the literature regarding the use of EMPs in these two systems are included. In the final section, we present a summary of the most relevant methods documented in the literature for the fabrication of EMPs, together with a list of the most common ferromagnetic materials that have been synthesized in the form of EMPs.

  10. Symmetry breaking of particle trajectories due to magnetic interactions in a dilute suspension

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, F.R., E-mail: frcunha@unb.br [Vortex Laboratory of Fluid Mechanics of Complex Flows and Departamento de Engenharia Mecanica, Faculdade de Tecnologia, Universidade de Brasilia, Campus Universitario Darcy Ribeiro, 70910-900 Brasilia, DF (Brazil); Gontijo, R.G., E-mail: rafaelgabler@gmail.com [Vortex Laboratory of Fluid Mechanics of Complex Flows and Departamento de Engenharia Mecanica, Faculdade de Tecnologia, Universidade de Brasilia, Campus Universitario Darcy Ribeiro, 70910-900 Brasilia, DF (Brazil); Sobral, Y.D., E-mail: ydsobral@unb.br [Vortex Laboratory of Fluid Mechanics of Complex Flows and Departamento de Matematica, Instituto de Ciencias Exatas, Universidade de Brasilia, Campus Universitario Darcy Ribeiro, 70910-900 Brasilia, DF (Brazil)

    2013-01-15

    This work presents a numerical study of the relative trajectories of two magnetic particles interacting in a dilute suspension. The suspension is composed of magnetic spherical particles of different radius and density immersed in a Newtonian fluid. The particles settle relative to one another under the action of gravity and, when in close proximity, exert on each other magnetic force and torque due to their permanent magnetization. The equations of motion for both translation and rotation of the particles are solved and particle inertia is included in the calculation. The numerical simulations are based on the direct computations of the hydrodynamic and of the magnetic interactions between the rigid particles in the regime of non-zero Stokes number. A detailed study of the relative trajectories of two magnetic particles in a dilute suspension allows us to explore irreversible interactions that lead to particle aggregation and particle migration induced by the breaking of the time reversibility of the creeping flow due to magnetic effects. The calculation shows that the rotation of the particles produced by magnetic interactions change significantly the dynamics of collisions of magnetic particle. - Highlights: Black-Right-Pointing-Pointer Relative trajectories of magnetic particles. Black-Right-Pointing-Pointer Magnetic interactions of particles under a gravity field. Black-Right-Pointing-Pointer Magnetic interactions break relative trajectories reversibility. Black-Right-Pointing-Pointer Particle Rotation decrease the rate of aggregation. Black-Right-Pointing-Pointer Dispersion in a magnetic suspension due to magnetic interactions.

  11. Oleic acid coated magnetic nano-particles: Synthesis and characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Panda, Biswajit, E-mail: bpanda@mes.ac.in; Goyal, P. S. [Pillai’s Institute of Information Technology, Engineering, Media Studies and Research, Dr. K. M. Vasudevan Pillai’s Campus, New Panvel, 410 206 (India)

    2015-06-24

    Magnetic nano particles of Fe{sub 3}O{sub 4} coated with oleic acid were synthesized using wet chemical route, which involved co-precipitation of Fe{sup 2+} and Fe{sup 3+} ions. The nano particles were characterized using XRD, TEM, FTIR, TGA and VSM. X-ray diffraction studies showed that nano particles consist of single phase Fe{sub 3}O{sub 4} having inverse spinel structure. The particle size obtained from width of Bragg peak is about 12.6 nm. TEM analysis showed that sizes of nano particles are in range of 6 to 17 nm with a dominant population at 12 - 14 nm. FTIR and TGA analysis showed that -COOH group of oleic acid is bound to the surface of Fe{sub 3}O{sub 4} particles and one has to heat the sample to 278° C to remove the attached molecule from the surface. Further it was seen that Fe{sub 3}O{sub 4} particles exhibit super paramagnetism with a magnetization of about 53 emu/ gm.

  12. Magnetic particle imaging: introduction to imaging and hardware realization.

    Science.gov (United States)

    Buzug, Thorsten M; Bringout, Gael; Erbe, Marlitt; Gräfe, Ksenija; Graeser, Matthias; Grüttner, Mandy; Halkola, Aleksi; Sattel, Timo F; Tenner, Wiebke; Wojtczyk, Hanne; Haegele, Julian; Vogt, Florian M; Barkhausen, Jörg; Lüdtke-Buzug, Kerstin

    2012-12-01

    Magnetic Particle Imaging (MPI) is a recently invented tomographic imaging method that quantitatively measures the spatial distribution of a tracer based on magnetic nanoparticles. The new modality promises a high sensitivity and high spatial as well as temporal resolution. There is a high potential of MPI to improve interventional and image-guided surgical procedures because, today, established medical imaging modalities typically excel in only one or two of these important imaging properties. MPI makes use of the non-linear magnetization characteristics of the magnetic nanoparticles. For this purpose, two magnetic fields are created and superimposed, a static selection field and an oscillatory drive field. If superparamagnetic iron-oxide nanoparticles (SPIOs) are subjected to the oscillatory magnetic field, the particles will react with a non-linear magnetization response, which can be measured with an appropriate pick-up coil arrangement. Due to the non-linearity of the particle magnetization, the received signal consists of the fundamental excitation frequency as well as of harmonics. After separation of the fundamental signal, the nanoparticle concentration can be reconstructed quantitatively based on the harmonics. The spatial coding is realized with the static selection field that produces a field-free point, which is moved through the field of view by the drive fields. This article focuses on the frequency-based image reconstruction approach and the corresponding imaging devices while alternative concepts like x-space MPI and field-free line imaging are described as well. The status quo in hardware realization is summarized in an overview of MPI scanners.

  13. Magnetic particles as affinity matrix for purification of antithrombin

    Science.gov (United States)

    Mercês, A. A. D.; Maciel, J. C.; Carvalho Júnior, L. B.

    2015-11-01

    Immobilization of biomolecules onto insoluble supports is an important tool for the fabrication of a diverse range of functional materials. It provides advantages: enhanced stability and easy separation. In this work two different magnetic composites were synthesized (MAG-PANI-HS and mDAC-HS) to human antithrombin purification. The magnetic particles (MAG) were obtained by co-precipitation method of iron salts II and III and subsequently coated with polyaniline (MAG-PANI particles). Dacron (polyethylene terephthalate) suffered a hydrazinolysis reaction to obtain a powder (Dacron hydrazide) which was subsequently magnetized (mDAC particles) also by co-precipitation method. Heparan sulfate (HS) was immobilized to MAG-PANI and mDAC retained respectively 35μg and 38.6μg per of support. The magnetic composite containing HS immobilized (MAG-PANI-HS and mDAC-HS) was incubated with human blood plasma (1mL) and then washed with NaCl gradients. Electrophoresis of proteins present in eluates showed bands of antithrombin (58kDa). A reduction in the antithrombin activity was detected in plasma that were incubated in the composites magnetic with HS immobilized, suggesting that the antithrombin was removed of the human blood plasma and then purified. Therefore, the above results suggest that both preparations: MAG-PANI-HS and mDAC-HS are able to affinity purify antithrombin, an important component of blood coagulation.

  14. Dust Particle Dynamics in The Presence of Highly Magnetized Plasmas

    Science.gov (United States)

    Lynch, Brian; Konopka, Uwe; Thomas, Edward; Merlino, Robert; Rosenberg, Marlene

    2016-10-01

    Complex plasmas are four component plasmas that contain, in addition to the usual electrons, ions, and neutral atoms, macroscopic electrically charged (nanometer to micrometer) sized ``dust'' particles. These macroscopic particles typically obtain a net negative charge due to the higher mobility of electrons compared to that of ions. Because the electrons, ions, and dust particles are charged, their dynamics may be significantly modified by the presence of electric and magnetic fields. Possible consequences of this modification may be the charging rate and the equilibrium charge. For example, in the presence of a strong horizontal magnetic field (B >1 Tesla), it may be possible to observe dust particle gx B deflection and, from that deflection, determine the dust grain charge. In this poster, we present recent data from performing multiple particle dropping experiments to characterize the g x B deflection in the Magnetized Dusty Plasma Experiment (MDPX). This work is supported by funding from the U. S. Department of Energy Grant Number DE - SC0010485 and the NASA/Jet Propulsion Laboratory, JPL-1543114.

  15. Heliospheric Magnetic Fields, Energetic Particles, and the Solar Cycle

    Indian Academy of Sciences (India)

    Peter Kiraly

    2000-09-01

    The heliosphere is the region filled with magnetized plasma of mainly solar origin. It extends from the solar corona to well beyond the planets, and is separated from the interstellar medium by the heliopause. The latter is embedded in a complex and still unexplored boundary region. The characteristics of heliospheric plasma, fields, and energetic particles depend on highly variable internal boundary conditions, and also on quasi-stationary external ones. Both galactic cosmic rays and energetic particles of solar and heliospheric origin are subject to intensity variations over individual solar cycles and also from cycle to cycle. Particle propagation is controlled by spatially and temporally varying interplanetary magnetic fields, frozen into the solar wind. An overview is presented of the main heliospheric components and processes, and also of the relevant missions and data sets. Particular attention is given to flux variations over the last few solar cycles, and to extrapolated effects on the terrestrial environment.

  16. Dual-frequency magnetic particle imaging of the Brownian particle contribution

    Science.gov (United States)

    Viereck, Thilo; Kuhlmann, Christian; Draack, Sebastian; Schilling, Meinhard; Ludwig, Frank

    2017-04-01

    Magnetic particle imaging (MPI) is an emerging medical imaging modality based on the non-linear response of magnetic nanoparticles to an exciting magnetic field. MPI has been recognized as a fast imaging technique with high spatial resolution in the mm range. For some applications of MPI, especially in the field of functional imaging, the determination of the particle mobility (Brownian rotation) is of great interest, as it enables binding detection in MPI. It also enables quantitative imaging in the presence of Brownian-dominated particles, which is otherwise implausible. Discrimination of different particle responses in MPI is possible via the joint reconstruction approach. In this contribution, we propose a dual-frequency acquisition scheme to enhance sensitivity and contrast in the detection of different particle mobilities compared to a standard single-frequency MPI protocol. The method takes advantage of the fact, that the magnetization response of the tracer is strongly frequency-dependent, i.e. for low excitation frequencies a stronger Brownian contribution is observed.

  17. Particle acceleration, magnetization and radiation in relativistic shocks

    Science.gov (United States)

    Derishev, Evgeny V.; Piran, Tsvi

    2016-08-01

    The mechanisms of particle acceleration and radiation, as well as magnetic field build-up and decay in relativistic collisionless shocks, are open questions with important implications to various phenomena in high-energy astrophysics. While the Weibel instability is possibly responsible for magnetic field build-up and diffusive shock acceleration is a model for acceleration, both have problems and current particle-in-cell simulations show that particles are accelerated only under special conditions and the magnetic field decays on a very short length-scale. We present here a novel model for the structure and the emission of highly relativistic collisionless shocks. The model takes into account (and is based on) non-local energy and momentum transport across the shock front via emission and absorption of high-energy photons. This leads to a pre-acceleration of the fluid and pre-amplification of the magnetic fields in the upstream region. Both have drastic implications on the shock structure. The model explains the persistence of the shock-generated magnetic field at large distances from the shock front. The dissipation of this magnetic field results in a continuous particle acceleration within the downstream region. A unique feature of the model is the existence of an `attractor', towards which any shock will evolve. The model is applicable to any relativistic shock, but its distinctive features show up only for sufficiently large compactness. We demonstrate that prompt and afterglow gamma-ray bursts' shocks satisfy the relevant conditions, and we compare their observations with the predictions of the model.

  18. Chaotic motion of charged particles in toroidal magnetic configurations.

    Science.gov (United States)

    Cambon, Benjamin; Leoncini, Xavier; Vittot, Michel; Dumont, Rémi; Garbet, Xavier

    2014-09-01

    We study the motion of a charged particle in a tokamak magnetic field and discuss its chaotic nature. Contrary to most of recent studies, we do not make any assumption on any constant of the motion and solve numerically the cyclotron gyration using Hamiltonian formalism. We take advantage of a symplectic integrator allowing us to make long-time simulations. First considering an idealized magnetic configuration, we add a nongeneric perturbation corresponding to a magnetic ripple, breaking one of the invariant of the motion. Chaotic motion is then observed and opens questions about the link between chaos of magnetic field lines and chaos of particle trajectories. Second, we return to an axisymmetric configuration and tune the safety factor (magnetic configuration) in order to recover chaotic motion. In this last setting with two constants of the motion, the presence of chaos implies that no third global constant exists, we highlight this fact by looking at variations of the first order of the magnetic moment in this chaotic setting. We are facing a mixed phase space with both regular and chaotic regions and point out the difficulties in performing a global reduction such as gyrokinetics.

  19. A characterisation of the magnetically induced movement of NdFeB-particles in magnetorheological elastomers

    Science.gov (United States)

    Schümann, M.; Borin, D. Y.; Huang, S.; Auernhammer, G. K.; Müller, R.; Odenbach, S.

    2017-09-01

    Magnetorheological elastomers are a type of smart hybrid material where elastic properties of a soft elastomer matrix are combined with magnetic properties of magnetic micro particles. This combination leads to a complex interplay of magnetic and elastic phenomena, of which the magnetorheological effect is the best described. In this paper, magnetically hard NdFeB-particles were used to obtain remanent magnetic properties. X-ray microtomography has been utilised to analyse the particle movement induced by magnetic fields. A particle tracking was performed; thus, it was possible to characterise the movement of individual particles. Beyond that, a comprehensive analysis of the orientation of all particles was performed at different states of magnetisation and global particle arrangements. For the first time, this method was successfully applied to a magnetorheological material with a technically relevant amount of magnetic NdFeB-particles. A significant impact of the magnetic field on the rotation and translation of the particles was shown.

  20. Fractional dynamics of charged particles in magnetic fields

    Science.gov (United States)

    Coronel-Escamilla, A.; Gómez-Aguilar, J. F.; Alvarado-Méndez, E.; Guerrero-Ramírez, G. V.; Escobar-Jiménez, R. F.

    2016-02-01

    In many physical applications the electrons play a relevant role. For example, when a beam of electrons accelerated to relativistic velocities is used as an active medium to generate Free Electron Lasers (FEL), the electrons are bound to atoms, but move freely in a magnetic field. The relaxation time, longitudinal effects and transverse variations of the optical field are parameters that play an important role in the efficiency of this laser. The electron dynamics in a magnetic field is a means of radiation source for coupling to the electric field. The transverse motion of the electrons leads to either gain or loss energy from or to the field, depending on the position of the particle regarding the phase of the external radiation field. Due to the importance to know with great certainty the displacement of charged particles in a magnetic field, in this work we study the fractional dynamics of charged particles in magnetic fields. Newton’s second law is considered and the order of the fractional differential equation is (0;1]. Based on the Grünwald-Letnikov (GL) definition, the discretization of fractional differential equations is reported to get numerical simulations. Comparison between the numerical solutions obtained on Euler’s numerical method for the classical case and the GL definition in the fractional approach proves the good performance of the numerical scheme applied. Three application examples are shown: constant magnetic field, ramp magnetic field and harmonic magnetic field. In the first example the results obtained show bistability. Dissipative effects are observed in the system and the standard dynamic is recovered when the order of the fractional derivative is 1.

  1. Magnetic, Structural, and Particle Size Analysis of Single- and Multi-Core Magnetic Nanoparticles

    DEFF Research Database (Denmark)

    Ludwig, Frank; Kazakova, Olga; Barquin, Luis Fernandez

    2014-01-01

    We have measured and analyzed three different commercial magnetic nanoparticle systems, both multi-core and single-core in nature, with the particle (core) size ranging from 20 to 100 nm. Complementary analysis methods and same characterization techniques were carried out in different labs...... and the results are compared with each other. The presented results primarily focus on determining the particle size—both the hydrodynamic size and the individual magnetic core size—as well as magnetic and structural properties. The used analysis methods include transmission electron microscopy, static...... and dynamic magnetization measurements, and Mössbauer spectroscopy. We show that particle (hydrodynamic and core) size parameters can be determined from different analysis techniques and the individual analysis results agree reasonably well. However, in order to compare size parameters precisely determined...

  2. Quantitative Magnetic Separation of Particles and Cells Using Gradient Magnetic Ratcheting.

    Science.gov (United States)

    Murray, Coleman; Pao, Edward; Tseng, Peter; Aftab, Shayan; Kulkarni, Rajan; Rettig, Matthew; Di Carlo, Dino

    2016-04-13

    Extraction of rare target cells from biosamples is enabling for life science research. Traditional rare cell separation techniques, such as magnetic activated cell sorting, are robust but perform coarse, qualitative separations based on surface antigen expression. A quantitative magnetic separation technology is reported using high-force magnetic ratcheting over arrays of magnetically soft micropillars with gradient spacing, and the system is used to separate and concentrate magnetic beads based on iron oxide content (IOC) and cells based on surface expression. The system consists of a microchip of permalloy micropillar arrays with increasing lateral pitch and a mechatronic device to generate a cycling magnetic field. Particles with higher IOC separate and equilibrate along the miropillar array at larger pitches. A semi-analytical model is developed that predicts behavior for particles and cells. Using the system, LNCaP cells are separated based on the bound quantity of 1 μm anti-epithelial cell adhesion molecule (EpCAM) particles as a metric for expression. The ratcheting cytometry system is able to resolve a ±13 bound particle differential, successfully distinguishing LNCaP from PC3 populations based on EpCAM expression, correlating with flow cytometry analysis. As a proof-of-concept, EpCAM-labeled cells from patient blood are isolated with 74% purity, demonstrating potential toward a quantitative magnetic separation instrument.

  3. Theory of using magnetic deflections to combine charged particle beams

    Energy Technology Data Exchange (ETDEWEB)

    Steckbeck, Mackenzie K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Doyle, Barney Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

    Several radiation effects projects in the Ion Beam Lab (IBL) have recently required two disparate charged particle beams to simultaneously strike a single sample through a single port of the target chamber. Because these beams have vastly different mass–energy products (MEP), the low-MEP beam requires a large angle of deflection toward the sample by a bending electromagnet. A second electromagnet located further upstream provides a means to compensate for the small angle deflection experienced by the high-MEP beam during its path through the bending magnet. This paper derives the equations used to select the magnetic fields required by these two magnets to achieve uniting both beams at the target sample. A simple result was obtained when the separation of the two magnets was equivalent to the distance from the bending magnet to the sample, and the equation is given by: Bs= 1/2(rc/rs) Bc, where Bs and Bc are the magnetic fields in the steering and bending magnet and rc/rs is the ratio of the radii of the bending magnet to that of the steering magnet. This result is not dependent upon the parameters of the high MEP beam, i.e. energy, mass, charge state. Therefore, once the field of the bending magnet is set for the low-MEP beam, and the field in the steering magnet is set as indicted in the equation, the trajectory path of any high-MEP beam will be directed into the sample.

  4. Fabrication and manipulation of polymeric magnetic particles with magnetorheological fluid

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Lopez, Jaime [Centro de Acustica Aplicada y Evaluacion No Destructivos (CAEND), CSIC-UPM, C/Serrano 144, 28006, Madrid (Spain); Shum, Ho Cheung, E-mail: ashum@hku.hk [Department of Mechanical Engineering, University of Hong Kong, 7/F Haking Wong Building, Pokfulam Road (Hong Kong); Elvira, Luis; Montero de Espinosa, Francisco [Centro de Acustica Aplicada y Evaluacion No Destructivos (CAEND), CSIC-UPM, C/Serrano 144, 28006, Madrid (Spain); Weitz, David A., E-mail: weitz@seas.harvard.edu [Department of Physics and School of Engineering and Applied Sciences, Harvard University, 9 and 15 Oxford Street, Cambridge, MA 02138 (United States)

    2013-01-15

    Polymeric magnetic microparticles have been created using a microfluidic device via ultraviolet (UV) polymerization of double emulsions, resulting in cores of magnetorheological (MR) fluids surrounded by polymeric shells. We demonstrate that the resultant particles can be manipulated magnetically to achieve triggered rupture of the capsules. This illustrates the great potential of our capsules for triggered release of active ingredients encapsulated in the polymeric magnetic microparticles. - Highlights: Black-Right-Pointing-Pointer Polymeric microparticles encapsulating MR fluids have been fabricated. Black-Right-Pointing-Pointer A double-emulsion-templated approach using microfluidic techniques has been used. Black-Right-Pointing-Pointer The monodisperse microparticles obtained are easily manipulated under magnetic field. Black-Right-Pointing-Pointer These microparticles have great potential for encapsulation-and-release applications.

  5. Orbital polarization and magnetization for independent particles in disordered media

    CERN Document Server

    Schulz-Baldes, Hermann

    2012-01-01

    Formulas for the contribution of the conduction electrons to the polarization and magnetization are derived for disordered systems and within a one-particle framework. These results generalize known formulas for Bloch electrons and the presented proofs considerably simplify and strengthen prior justifications. The new formulas show that orbital polarization and magnetization are of geometric nature. This leads to quantization for a periodically driven Piezo effect as well as the derivative of the magnetization w.r.t. the chemical potential. It is also shown how the latter is connected to boundary currents in Chern insulators. The main technical tools in the proofs are an adaption of Nenciu's super-adiabatic theory to C$^*$-dynamical systems and Bellissard's Ito derivatives w.r.t. the magnetic field.

  6. Transport coefficients and orientational distributions of spheroidal particles with magnetic moment normal to the particle axis (Analysis for an applied magnetic field normal to the shear plane).

    Science.gov (United States)

    Satoh, Akira; Ozaki, Masataka

    2006-06-15

    We have investigated the influence of the magnetic field strength, shear rate, and rotational Brownian motion on transport coefficients such as viscosity and diffusion coefficient, and also on the orientational distributions of rodlike particles of a dilute colloidal dispersion. The rodlike particle is modeled as a magnetic spheroidal particle which has a magnetic moment normal to the particle axis; such a particle may typically be a hematite particle. In the present study, an external magnetic field is applied in the direction normal to the shear plane of a simple shear flow. The basic equation of the orientational distribution function has been derived from the balance of torques and solved numerically. The results obtained here are summarized as follows. Although the orientational distribution function shows a sharp peak in the shear flow direction for a very strong magnetic field, such a peak is not restricted to the field direction alone, but continues in every direction of the shear plane. This is due to the characteristic particle motion that the particle can rotate around the axis of the magnetic moment in the shear plane, although the magnetic moment nearly points to the magnetic field direction. This particle motion in the shear plane causes negative values of the viscosity due to the magnetic field. The viscosity decreases, attains a minimum value, and then converges to zero as the field strength increases. Additionally, the diffusion coefficient is significantly influenced by such characteristic particle motion in the shear plane for a strong magnetic field.

  7. Biomarker detection of global infectious diseases based on magnetic particles.

    Science.gov (United States)

    Carinelli, Soledad; Martí, Mercè; Alegret, Salvador; Pividori, María Isabel

    2015-09-25

    Infectious diseases affect the daily lives of millions of people all around the world, and are responsible for hundreds of thousands of deaths, mostly in the developing world. Although most of these major infectious diseases are treatable, the early identification of individuals requiring treatment remains a major issue. The incidence of these diseases would be reduced if rapid diagnostic tests were widely available at the community and primary care level in low-resource settings. Strong research efforts are thus being focused on replacing standard clinical diagnostic methods, such as the invasive detection techniques (biopsy or endoscopy) or expensive diagnostic and monitoring methods, by affordable and sensitive tests based on novel biomarkers. The development of new methods that are needed includes solid-phase separation techniques. In this context, the integration of magnetic particles within bioassays and biosensing devices is very promising since they greatly improve the performance of a biological reaction. The diagnosis of clinical samples with magnetic particles can be easily achieved without pre-enrichment, purification or pretreatment steps often required for standard methods, simplifying the analytical procedures. The biomarkers can be specifically isolated and preconcentrated from complex biological matrixes by magnetic actuation, increasing specificity and the sensitivity of the assay. This review addresses these promising features of the magnetic particles for the detection of biomarkers in emerging technologies related with infectious diseases affecting global health, such as malaria, influenza, dengue, tuberculosis or HIV.

  8. Reflected Charged Particle Populations around Dipolar Lunar Magnetic Anomalies

    Science.gov (United States)

    Deca, Jan; Divin, Andrey

    2016-10-01

    In this work we analyze and compare the reflected particle populations for both a horizontal and a vertical dipole model embedded in the lunar surface, representing the solar wind interaction with two different lunar magnetic anomaly (LMA) structures. Using the 3D full-kinetic electromagnetic code iPic3D, in combination with a test-particle approach to generate particle trajectories, we focus on the ion and electron dynamics. Whereas the vertical model electrostatically reflects ions upward under both near-parallel and near-perpendicular angles with respect to the lunar surface, the horizontal model only has a significant shallow component. Characterizing the electron dynamics, we find that the interplay of the mini-magnetosphere electric and magnetic fields is capable of temporarily trapping low-energy electrons and possibly ejecting them upstream. Our results are in agreement with recent high-resolution observations. Low- to medium-altitude ion and electron observations might be excellent indicators to complement orbital magnetic field measurements and better uncover the underlying magnetic field structure. The latter is of particular importance in defining the correlation between LMAs and lunar swirls, and further testing the solar wind shielding hypothesis for albedo markings due to space weathering. Observing more reflected ions does not necessarily point to the existence of a mini-magnetosphere.

  9. Magnetic coupling mechanisms in particle/thin film composite systems

    Directory of Open Access Journals (Sweden)

    Giovanni A. Badini Confalonieri

    2010-12-01

    Full Text Available Magnetic γ-Fe2O3 nanoparticles with a mean diameter of 20 nm and size distribution of 7% were chemically synthesized and spin-coated on top of a Si-substrate. As a result, the particles self-assembled into a monolayer with hexagonal close-packed order. Subsequently, the nanoparticle array was coated with a Co layer of 20 nm thickness. The magnetic properties of this composite nanoparticle/thin film system were investigated by magnetometry and related to high-resolution transmission electron microscopy studies. Herein three systems were compared: i.e. a reference sample with only the particle monolayer, a composite system where the particle array was ion-milled prior to the deposition of a thin Co film on top, and a similar composite system but without ion-milling. The nanoparticle array showed a collective super-spin behavior due to dipolar interparticle coupling. In the composite system, we observed a decoupling into two nanoparticle subsystems. In the ion-milled system, the nanoparticle layer served as a magnetic flux guide as observed by magnetic force microscopy. Moreover, an exchange bias effect was found, which is likely to be due to oxygen exchange between the iron oxide and the Co layer, and thus forming of an antiferromagnetic CoO layer at the γ-Fe2O3/Co interface.

  10. Selective activation of mechanosensitive ion channels using magnetic particles.

    Science.gov (United States)

    Hughes, Steven; McBain, Stuart; Dobson, Jon; El Haj, Alicia J

    2008-08-01

    This study reports the preliminary development of a novel magnetic particle-based technique that permits the application of highly localized mechanical forces directly to specific regions of an ion-channel structure. We demonstrate that this approach can be used to directly and selectively activate a mechanosensitive ion channel of interest, namely TREK-1. It is shown that manipulation of particles targeted against the extended extracellular loop region of TREK-1 leads to changes in whole-cell currents consistent with changes in TREK-1 activity. Responses were absent when particles were coated with RGD (Arg-Gly-Asp) peptide or when magnetic fields were applied in the absence of magnetic particles. It is concluded that changes in whole-cell current are the result of direct force application to the extracellular loop region of TREK-1 and thus these results implicate this region of the channel structure in mechano-gating. It is hypothesized that the extended loop region of TREK-1 may act as a tension spring that acts to regulate sensitivity to mechanical forces, in a nature similar to that described for MscL. The development of a technique that permits the direct manipulation of mechanosensitive ion channels in real time without the need for pharmacological drugs has huge potential benefits not only for basic biological research of ion-channel gating mechanisms, but also potentially as a tool for the treatment of human diseases caused by ion-channel dysfunction.

  11. Charged particle motion near a linear magnetic null

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.; Cary, J.R.

    1983-08-01

    Charged particle motion near the null of a two-dimensional magnetic field is studied. Specifically, the magnetic field is given by the vector potential A = zpsi/sub 0/((y/a)/sup 2/+(epsilonx/a)/sup 2/), in which psi/sub 0/,a, and epsilon are constants with epsilon parameterizing the ellipticity of the flux surfaces. Conservation of canonical z momentum p/sub z/ reduces the number of nontrivial degrees of freedom to two. Scaling reduces the number of parameters in the system to two, epsilon and sigma (the sign of p/sub z/ ). Analytical and numerical methods are used to study the nature of orbits. The results are expressed conveniently in terms of epsilon and Qequivalent(2mE)/sup 1/2//p/sub z/. When epsilon is unity, the additional symmetry implies integrability. When epsilon is less than unity (the case epsilon>1 is trivially related) three regimes are found: (1) For Vertical BarQVertical Bar>>1 particle orbits are regular, (2) for epsilon/sup 3/2/< or approx. =Vertical BarQVertical Bar< or approx. =1 most particle orbits are stochastic, and (3) for Vertical BarQVertical Bar<particle orbits are regular, with the third invariant being the magnetic moment.

  12. Particle Acceleration in Relativistic Magnetized Collisionless Electron-Ion Shocks

    CERN Document Server

    Sironi, Lorenzo

    2010-01-01

    We investigate shock structure and particle acceleration in relativistic magnetized collisionless electron-ion shocks by means of 2.5D particle-in-cell simulations with ion-to-electron mass ratios (m_i/m_e) ranging from 16 to 1000. We explore a range of inclination angles between the pre-shock magnetic field and the shock normal. In "subluminal" shocks, where relativistic particles can escape ahead of the shock along the magnetic field lines, ions are efficiently accelerated via a Fermi-like mechanism. The downstream ion spectrum consists of a relativistic Maxwellian and a high-energy power-law tail, which contains ~5% of ions and ~30% of ion energy. Its slope is -2.1. Upstream electrons enter the shock with lower energy than ions, so they are more strongly tied to the field. As a result, only ~1% of the incoming electrons are Fermi-accelerated at the shock before being advected downstream, where they populate a steep power-law tail (with slope -3.5). For "superluminal" shocks, where relativistic particles ca...

  13. Hydrodynamic and magnetic fractionation of superparamagnetic nanoparticles for magnetic particle imaging

    Energy Technology Data Exchange (ETDEWEB)

    Löwa, Norbert, E-mail: norbert.loewa@ptb.de [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany); Knappe, Patrick [Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, 12205 Berlin (Germany); Wiekhorst, Frank; Eberbeck, Dietmar [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany); Thünemann, Andreas F. [Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, 12205 Berlin (Germany); Trahms, Lutz [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany)

    2015-04-15

    Resovist{sup ®} originally developed as a clinical liver contrast agent for Magnetic Resonance Imaging exhibits also an outstanding performance as a tracer in Magnetic Particle Imaging (MPI). In order to study the physical mechanism of the high MPI performance of Resovist{sup ®}, we applied asymmetric flow field–flow fractionation (A4F) and static magnetic fractionation (SMF) to separate Resovist{sup ®} into a set of fractions with defined size classes. As A4F based on an elution method separates MNP according to their hydrodynamic size, SMF fractionates a particle distribution by its magnetic moment. The obtained fractions of both separation techniques were then magnetically characterized by magnetorelaxometry measurements to extract the corresponding effective magnetic anisotropy and hydrodynamic size distribution parameters. Additionally, the MPI performance of each fraction was assessed using magnetic particle spectroscopy. With both separation techniques fractions (normalized to their iron amount) an MPI signal gain of a factor of two could be obtained, even though the distribution of effective anisotropy and hydrodynamic size were significantly different. Relating these findings to the results from magnetic characterization allows for a better understanding of the underlying mechanisms of MPI performance of Resovist{sup ®}. This knowledge may help to improve the design of novel MPI tracers and development of separation methods.

  14. Test particle acceleration in torsional spine magnetic reconnection

    Science.gov (United States)

    Hosseinpour, M.

    2014-10-01

    Three-dimensional (3D) magnetic reconnection is taking place commonly in astrophysical and space plasmas, especially in solar flares which are rich sources of highly energetic particles. One of the proposed mechanisms for steady-state 3D magnetic reconnection is "torsional spine reconnection". By using the magnetic and electric fields for "torsional spine reconnection", we numerically investigate the features of test particle acceleration with input parameters for the solar corona. We show that efficient acceleration of a relativistic proton is possible near the null point where it can gain up to 100 MeV of kinetic energy within a few milliseconds. However, varying the injection position results in different scenarios for proton acceleration. A proton is most efficiently accelerated when it is injected at the point where the magnetic field lines change their curvature in the fan plane. Moreover, a proton injected far away from the null point cannot be accelerated and, even in some cases, it is trapped in the magnetic field. In addition, adopting either spatially uniform or non-uniform localized plasma resistivity does not much influence the features of trajectory.

  15. Magnetic Particle Detection (MPD) for In-Vitro Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Minard, Kevin R.; Littke, Matthew H.; Wang, Wei; Xiong, Yijia; Teeguarden, Justin G.; Thrall, Brian D.

    2013-05-15

    In-vitro tests intended for evaluating the potential health effects of magnetic nanoparticles generally require an accurate measure of cell dose to promote the consistent use and interpretation of biological response. Here, a simple low-cost inductive sensor is developed for quickly determining the total mass of magnetic nanoparticles that is bound to the plasma membrane and internalized by cultured cells. Sensor operation exploits an oscillating magnetic field (f0 = 250 kHz) together with the nonlinear response of particle magnetization to generate a harmonic signal (f3 = 750 kHz) that varies linearly with particulate mass (R2 > 0.999) and is sufficiently sensitive for detecting ~ 100 ng of carboxyl-coated iron-oxide nanoparticles in under a second. When exploited for measuring receptor-mediated nanoparticle uptake in RAW 264.7 macrophages, results show that achieved dosimetry performance is comparable with relatively expensive analytical techniques that are much more time-consuming and labor-intensive to perform. Described sensing is therefore potentially better suited for low-cost in-vitro assays that require fast and quantitative magnetic particle detection.

  16. Magnetic particle imaging an introduction to imaging principles and scanner instrumentation

    CERN Document Server

    Knopp, Tobias

    2012-01-01

    This is an overview of recent progress in magnetic particle imaging, which uses various static and oscillating magnetic fields and tracer materials made from iron oxide nanoparticles to perform background-free measurements of the particles' local concentration.

  17. Pose control of the chain composed of magnetic particles using external uniform and gradient magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, J. F., E-mail: zhoujianfeng@njtech.edu.cn; Shao, C. L.; Gu, B. Q. [Nanjing Tech University, School of Mechanical and Power Engineering (China)

    2016-01-15

    Magnetic particles (MPs) are known to respond to a magnetic field and can be moved by magnetic force, which make them good carriers in bioengineering and pharmaceutical engineering. In this paper, a pose control method for the straight chain composed of MPs is proposed, and the chain with one pose can be moved to another position with another pose using alternately employed uniform and gradient magnetic fields. Based on computer simulations, it is revealed that in the uniform magnetic field, the MPs form a straight chain with the same separation space along the field lines, and once the uniform magnetic field rotates, the chain also rotates with the field. In the gradient magnetic field, the MPs move toward the higher field so that the translation of the chain can be realized. The simulation results indicate that while the uniform magnetic field is rotating, there exists certain hysteresis between the chain and the field, and the chain is not straight anymore. So the uniform magnetic field should rest at the target angle for a period to make the chain fully relax to be straight. For nanoMP, its magnetic moment directly determines the gradient magnetic force which is much smaller than the dipole–dipole force among MPs. Therefore, the translation of the chain is much more time-consuming than rotation. To enlarge the translational velocity, it is suggested to increase the size of MPs or the magnetic field gradient.

  18. Magnetic particle hyperthermia—a promising tumour therapy?

    Science.gov (United States)

    Dutz, Silvio; Hergt, Rudolf

    2014-11-01

    We present a critical review of the state of the art of magnetic particle hyperthermia (MPH) as a minimal invasive tumour therapy. Magnetic principles of heating mechanisms are discussed with respect to the optimum choice of nanoparticle properties. In particular, the relation between superparamagnetic and ferrimagnetic single domain nanoparticles is clarified in order to choose the appropriate particle size distribution and the role of particle mobility for the relaxation path is discussed. Knowledge of the effect of particle properties for achieving high specific heating power provides necessary guidelines for development of nanoparticles tailored for tumour therapy. Nanoscale heat transfer processes are discussed with respect to the achievable temperature increase in cancer cells. The need to realize a well-controlled temperature distribution in tumour tissue represents the most serious problem of MPH, at present. Visionary concepts of particle administration, in particular by means of antibody targeting, are far from clinical practice, yet. On the basis of current knowledge of treating cancer by thermal damaging, this article elucidates possibilities, prospects, and challenges for establishment of MPH as a standard medical procedure.

  19. Accurate quantification of magnetic particle properties by intra-pair magnetophoresis for nanobiotechnology

    Science.gov (United States)

    van Reenen, Alexander; Gao, Yang; Bos, Arjen H.; de Jong, Arthur M.; Hulsen, Martien A.; den Toonder, Jaap M. J.; Prins, Menno W. J.

    2013-07-01

    The application of magnetic particles in biomedical research and in-vitro diagnostics requires accurate characterization of their magnetic properties, with single-particle resolution and good statistics. Here, we report intra-pair magnetophoresis as a method to accurately quantify the field-dependent magnetic moments of magnetic particles and to rapidly generate histograms of the magnetic moments with good statistics. We demonstrate our method with particles of different sizes and from different sources, with a measurement precision of a few percent. We expect that intra-pair magnetophoresis will be a powerful tool for the characterization and improvement of particles for the upcoming field of particle-based nanobiotechnology.

  20. Biosensor based on measurements of the clustering dynamics of magnetic particles

    DEFF Research Database (Denmark)

    2014-01-01

    Disclosed herein is a biosensor for optical detection of Brownian relaxation dynamics of magnetic particles measured by light transmission. The magnetic particles can be functionalized with biological ligands for the detection of target analytes in a sample.......Disclosed herein is a biosensor for optical detection of Brownian relaxation dynamics of magnetic particles measured by light transmission. The magnetic particles can be functionalized with biological ligands for the detection of target analytes in a sample....

  1. On the energization of charged particles by fast magnetic reconnection

    Science.gov (United States)

    Sharma, Rohit; Mitra, Dhrubaditya; Oberoi, Divya

    2017-09-01

    We study the role of turbulence in magnetic reconnection, within the framework of magnetohydrodynamics, using three-dimensional direct numerical simulations. For small turbulent intensity, we find that the reconnection rate obeys Sweet-Parker scaling. For large enough turbulent intensity, reconnection rate departs significantly from Sweet-Parker behaviour, becomes almost a constant as a function of the Lundquist number. We further study energization of test-particles in the same set-up. We find that the speed of the energized particles obeys a Maxwellian distribution, whose variance also obeys Sweet-Parker scaling for small turbulent intensity but depends weakly on the Lundquist number for large turbulent intensity. Furthermore, the variance is found to increase with the strength of the reconnecting magnetic field.

  2. On the energisation of charged particles by fast magnetic reconnection

    CERN Document Server

    Sharma, Rohit; Oberoi, Divya

    2016-01-01

    We study the role of turbulence in magnetic reconnection, within the framework of magneto-hydrodynamics, using three-dimensional direct numerical simulations. For small turbulent intensity we find that the reconnection rate obeys Sweet-Parker scaling. For large enough turbulent intensity reconnection rate departs significantly from Sweet-Parker behaviour, becomes almost a constant as a function of the Lundquist number. We further study energisation of test-particles in the same setup. We find that the speed of the energised particles obeys a Maxwellian distribution, whose variance also obeys Sweet-Parker scaling for small turbulent intensity but depends weakly on the Lundquist number for large turbulent intensity. Furthermore, the variance is found to increase with the strength of the reconnecting magnetic field.

  3. Arnold Diffusion of Charged Particles in ABC Magnetic Fields

    Science.gov (United States)

    Luque, Alejandro; Peralta-Salas, Daniel

    2017-06-01

    We prove the existence of diffusing solutions in the motion of a charged particle in the presence of ABC magnetic fields. The equations of motion are modeled by a 3DOF Hamiltonian system depending on two parameters. For small values of these parameters, we obtain a normally hyperbolic invariant manifold and we apply the so-called geometric methods for a priori unstable systems developed by A. Delshams, R. de la Llave and T.M. Seara. We characterize explicitly sufficient conditions for the existence of a transition chain of invariant tori having heteroclinic connections, thus obtaining global instability (Arnold diffusion). We also check the obtained conditions in a computer-assisted proof. ABC magnetic fields are the simplest force-free-type solutions of the magnetohydrodynamics equations with periodic boundary conditions, and can be considered as an elementary model for the motion of plasma-charged particles in a tokamak.

  4. Visual Basic VPython Interface: Charged Particle in a Magnetic Field

    Science.gov (United States)

    Prayaga, Chandra

    2006-12-01

    A simple Visual Basic (VB) to VPython interface is described and illustrated with the example of a charged particle in a magnetic field. This interface allows data to be passed to Python through a text file read by Python. The first component of the interface is a user-friendly data entry screen designed in VB, in which the user can input values of the charge, mass, initial position and initial velocity of the particle, and the magnetic field. Next, a command button is coded to write these values to a text file. Another command button starts the VPython program, which reads the data from the text file, numerically solves the equation of motion, and provides the 3d graphics animation. Students can use the interface to run the program several times with different data and observe changes in the motion.

  5. Magnetic particle translation as a surrogate measure for synovial fluid mechanics.

    Science.gov (United States)

    Shah, Yash Y; Maldonado-Camargo, Lorena; Patel, Neal S; Biedrzycki, Adam H; Yarmola, Elena G; Dobson, Jon; Rinaldi, Carlos; Allen, Kyle D

    2017-07-26

    The mechanics of synovial fluid vary with disease progression, but are difficult to quantify quickly in a clinical setting due to small sample volumes. In this study, a novel technique to measure synovial fluid mechanics using magnetic nanoparticles is introduced. Briefly, microspheres embedded with superparamagnetic iron oxide nanoparticles, termed magnetic particles, are distributed through a 100μL synovial fluid sample. Then, a permanent magnet inside a protective sheath is inserted into the synovial fluid sample. Magnetic particles translate toward the permanent magnet and the percentage of magnetic particles collected by the magnet in a given time can be related to synovial fluid viscosity. To validate this relationship, magnetic particle translation was demonstrated in three phases. First, magnetic particle translation was assessed in glycerol solutions with known viscosities, demonstrating that as fluid viscosity increased, magnetic particle translation decreased. Next, the relationship between magnetic particle translation and synovial fluid viscosity was assessed using bovine synovial fluid that was progressively degenerated via ultrasonication. Here, particle collection in a given amount of time increased as fluid degenerated, demonstrating that the relationship between particle collection and fluid mechanics holds in non-Newtonian synovial fluid. Finally, magnetic particle translation was used to assess differences between healthy and OA affected joints in equine synovial fluid. Here, particle collection in a given time was higher in OA joints relative to healthy horses (pmagnetic particle translation in a clinical setting to evaluate synovial fluid mechanics in limited volumes of synovial fluid sample. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Magnetic relaxation in chain-of-spheres ferromagnetic particles

    CERN Document Server

    Yang, J S

    2002-01-01

    The thermal activation of elongated ferromagnetic particles is analyzed using a chain-of-spheres model. The spheres within the chain are assumed to be coupled magnetically with dipolar interaction. The effect of uniaxial magnetocrystalline anisotropy along the chain is also taken into account. It was shown that the behavior of thermal switching critically depends on the relative strength of shape anisotropy and magnetocrystalline anisotropy, field orientation, sweep field rate and temperature.

  7. Optimal interactions of light with magnetic and electric resonant particles

    CERN Document Server

    Colom, Remi; Bonod, Nicolas; Stout, Brian

    2015-01-01

    This work studies the limits of far and near-field electromagnetic response of sub-wavelength scatterers, like the unitary limit and of lossless scatterers, and the ideal absorption limit of lossy particles. These limit behaviors are described in terms of analytic formulas that approximate finite size effects while rigorously including radiative corrections. This analysis predicts the electric and/or magnetic limit responses of both metallic and dielectric nanoparticles while quantitatively describing near-field enhancements.

  8. Precision Tension Control System Using Magnetic Particle Clutch

    Institute of Scientific and Technical Information of China (English)

    王春香; 杨汝清; 王永章; 路华

    2004-01-01

    The control of the stability of the filament tension is one of the crucial techniques ensuring the component quality of the composite materials. The open-loop tension control system, with industrial control computer as the core,magnetic particle clutch as the actuator, equipped with compensation technique is researched and manufactured.It can assure the tension control stability of the yarn in filament winding process and increase the control precision of the whole system.

  9. Magnetic Field Generation and Particle Energization in Relativistic Shear Flows

    Science.gov (United States)

    Liang, Edison; Boettcher, Markus; Smith, Ian

    2012-10-01

    We present Particle-in-Cell simulation results of magnetic field generation by relativistic shear flows in collisionless electron-ion (e-ion) and electron-positron (e+e-) plasmas. In the e+e- case, small current filaments are first generated at the shear interface due to streaming instabilities of the interpenetrating particles from boundary perturbations. Such current filaments create transverse magnetic fields which coalesce into larger and larger flux tubes with alternating polarity, eventually forming ordered flux ropes across the entire shear boundary layer. Particles are accelerated across field lines to form power-law tails by semi-coherent electric fields sustained by oblique Langmuir waves. In the e-ion case, a single laminar slab of transverse flux rope is formed at the shear boundary, sustained by thin current sheets on both sides due to different drift velocities of electrons and ions. The magnetic field has a single polarity for the entire boundary layer. Electrons are heated to a fraction of the ion energy, but there is no evidence of power-law tail forming in this case.

  10. Viscous properties of ferrofluids containing both micrometer-size magnetic particles and fine needle-like particles

    Science.gov (United States)

    Ido, Yasushi; Nishida, Hitoshi; Iwamoto, Yuhiro; Yokoyama, Hiroki

    2017-06-01

    Ferrofluids containing both micrometer-size spherical magnetic particles and nanometer-size needle-like nonmagnetic hematite particles were newly produced. Average length of long axis of the needle-like nonmagnetic particles was 194 nm and the aspect ratio was 8.3. Shear stress and viscosity were measured using the rheometer with the additional equipment for viscosity measurements in the presence of magnetic field. When the total volume fraction of particles in the fluid is constant (0.30), there is the specific mixing ratio of the particles to increase viscosity of the fluid drastically in the absence of magnetic field due to the percolation phenomenon. The fluid of the specific mixing ratio shows solid-like behavior even in the absence of magnetic field. Mixing the needle-like nonmagnetic particles causes strong yield stress and strong viscous force in the presence of magnetic field.

  11. Control of lattice spacing in a triangular lattice of feeble magnetic particles formed by induced magnetic dipole interactions

    Directory of Open Access Journals (Sweden)

    Noriyuki Hirota, Tsutomu Ando, Ryo Tanaka, Hitoshi Wada and Yoshio Sakka

    2009-01-01

    Full Text Available We studied methods of controlling the spacing between particles in the triangular lattice formed by feeble magnetic particles through induced magnetic dipole interaction. Formation of a triangular lattice is described by the balance between the magnetic force and the interaction of induced magnetic dipoles. The intensity of the magnetic force is proportional to the volume of particles V and the difference in the magnetic susceptibilities between the particles and the surrounding medium Δχ. On the other hand, the intensity of the induced magnetic dipole interaction depends on the square of V and Δχ. Therefore, altering the magnetic susceptibility difference by changing the susceptibility of the surrounding medium, volume of the particles, and intensity and spatial distribution of the applied magnetic field effectively controls the distance between the particles. In this study, these three methods were evaluated through experiment and molecular dynamics simulations. The distance between the particles, i.e. the lattice constant of the triangular lattice, was varied from 1.7 to 4.0 in units of the particle diameter. Formation of self-organized triangular lattice through the induced magnetic dipole interaction is based on magnetism, a physical property that all materials have. Therefore, this phenomenon is applicable to any materials of any size. Consequently, structure formation through induced magnetic dipole interaction is a potential way of fabricating materials with ordered structures.

  12. Optical measurement of anisotropic magnetic susceptibility for diamagnetic fine particles

    Science.gov (United States)

    Kitamura, Naoyuki; Takahashi, Kohki; Mogi, Iwao; Awaji, Satoshi; Watanabe, Kazuo

    2016-01-01

    We have developed an apparatus that allows the observation of the transient rotational motion of fine particles under a high magnetic field in order to determine anisotropic magnetic susceptibility. The anisotropic susceptibilities of spherical nanoparticles of bismuth and commercially available carbon nanofibers were determined. The estimated Δχ = 3.9 × 10-5 of spherical bismuth nanoparticles with a diameter of 370 nm was fairly consistent with the value determined previously by the magnetic field dependence of diffraction peak intensity in the X-ray diffraction (XRD) pattern, but was slightly smaller than the value for the bulk crystal. In contrast, the transient behavior of carbon nanofibers did not obey the theoretical motion of a single crystal. The wide distribution of fiber lengths, the irregularity of the structure in the fiber, and the connections between the fibers are suggested for the anomalous behavior.

  13. Ferromagnetic particles as magnetic resonance imaging temperature sensors.

    Science.gov (United States)

    Hankiewicz, J H; Celinski, Z; Stupic, K F; Anderson, N R; Camley, R E

    2016-08-09

    Magnetic resonance imaging is an important technique for identifying different types of tissues in a body or spatial information about composite materials. Because temperature is a fundamental parameter reflecting the biological status of the body and individual tissues, it would be helpful to have temperature maps superimposed on spatial maps. Here we show that small ferromagnetic particles with a strong temperature-dependent magnetization, can be used to produce temperature-dependent images in magnetic resonance imaging with an accuracy of about 1 °C. This technique, when further developed, could be used to identify inflammation or tumours, or to obtain spatial maps of temperature in various medical interventional procedures such as hyperthermia and thermal ablation. This method could also be used to determine temperature profiles inside nonmetallic composite materials.

  14. Method for using magnetic particles in droplet microfluidics

    Science.gov (United States)

    Shah, Gaurav Jitendra (Inventor); Kim, Chang-Jin (Inventor)

    2012-01-01

    Methods of utilizing magnetic particles or beads (MBs) in droplet-based (or digital) microfluidics are disclosed. The methods may be used in enrichment or separation processes. A first method employs the droplet meniscus to assist in the magnetic collection and positioning of MBs during droplet microfluidic operations. The sweeping movement of the meniscus lifts the MBs off the solid surface and frees them from various surface forces acting on the MBs. A second method uses chemical additives to reduce the adhesion of MBs to surfaces. Both methods allow the MBs on a solid surface to be effectively moved by magnetic force. Droplets may be driven by various methods or techniques including, for example, electrowetting, electrostatic, electromechanical, electrophoretic, dielectrophoretic, electroosmotic, thermocapillary, surface acoustic, and pressure.

  15. Particle acceleration, magnetization and radiation in relativistic shocks

    CERN Document Server

    Derishev, Evgeny V

    2015-01-01

    What are the mechanisms of particle acceleration and radiation, as well as magnetic field build up and decay in relativistic shocks are open questions with important implications to various phenomena in high energy astrophysics. While the Weibel instability is possibly responsible for magnetic field build up and diffusive shock acceleration is a model for acceleration, both have problems and current PIC simulation show that particles are accelerated only under special conditions and the magnetic field decays on a short length scale. We present here a novel model for the structure and the emission of highly relativistic collisionless shocks. The model takes into account (and is based on) non-local energy and momentum transport across the shock front via emission and absorption of high-energy photons. This leads to a pre-acceleration of the fluid and pre-amplificaiton of the magnetic fields in the upstream region. Both have drastic implications on the shock structure. The model explains the persistence of the s...

  16. Consistent energy barrier distributions in magnetic particle chains

    Energy Technology Data Exchange (ETDEWEB)

    Laslett, O., E-mail: O.Laslett@soton.ac.uk [Engineering and the Environment, University of Southampton, Southampton, SO16 7QF (United Kingdom); Ruta, S.; Chantrell, R.W. [Department of Physics, University of York, York YO10 5DD (United Kingdom); Barker, J. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Friedman, G. [Electrical and Computer Engineering Department, Drexel University, Philadelphia, PA 19104 (United States); Hovorka, O. [Engineering and the Environment, University of Southampton, Southampton, SO16 7QF (United Kingdom)

    2016-04-01

    We investigate long-time thermal activation behaviour in magnetic particle chains of variable length. Chains are modelled as Stoner–Wohlfarth particles coupled by dipolar interactions. Thermal activation is described as a hopping process over a multidimensional energy landscape using the discrete orientation model limit of the Landau–Lifshitz–Gilbert dynamics. The underlying master equation is solved by diagonalising the associated transition matrix, which allows the evaluation of distributions of time scales of intrinsic thermal activation modes and their energy representation. It is shown that as a result of the interaction dependence of these distributions, increasing the particle chain length can lead to acceleration or deceleration of the overall relaxation process depending on the initialisation procedure.

  17. Simulations of Energetic Particles Interacting with Dynamical Magnetic Turbulence

    Science.gov (United States)

    Hussein, M.; Shalchi, A.

    2016-02-01

    We explore the transport of energetic particles in interplanetary space by using test-particle simulations. In previous work such simulations have been performed by using either magnetostatic turbulence or undamped propagating plasma waves. In the current paper we simulate for the first time particle transport in dynamical turbulence. To do so we employ two models, namely the damping model of dynamical turbulence and the random sweeping model. We compute parallel and perpendicular diffusion coefficients and compare our numerical findings with solar wind observations. We show that good agreement can be found between simulations and the Palmer consensus range for both dynamical turbulence models if the ratio of turbulent magnetic field and mean field is δB/B0 = 0.5.

  18. Online reconstruction of 3D magnetic particle imaging data

    Science.gov (United States)

    Knopp, T.; Hofmann, M.

    2016-06-01

    Magnetic particle imaging is a quantitative functional imaging technique that allows imaging of the spatial distribution of super-paramagnetic iron oxide particles at high temporal resolution. The raw data acquisition can be performed at frame rates of more than 40 volumes s-1. However, to date image reconstruction is performed in an offline step and thus no direct feedback is available during the experiment. Considering potential interventional applications such direct feedback would be mandatory. In this work, an online reconstruction framework is implemented that allows direct visualization of the particle distribution on the screen of the acquisition computer with a latency of about 2 s. The reconstruction process is adaptive and performs block-averaging in order to optimize the signal quality for a given amount of reconstruction time.

  19. Particles that slide over the water surface: Synthesis and characterization of iron oxides particles coated with PDMS, with hydrophobic and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Souza Neto, Francisco N.de [Sciences and Technology Unit of the University – UnUCET, State University of Goiás, 75132-903 Anápolis, GO (Brazil); Araújo, Olacir Alves, E-mail: olacir.araujo@ueg.br [Sciences and Technology Unit of the University – UnUCET, State University of Goiás, 75132-903 Anápolis, GO (Brazil); Guilherme, Luciana R.; Garg, Vijayendra K. [Sciences and Technology Unit of the University – UnUCET, State University of Goiás, 75132-903 Anápolis, GO (Brazil); Oliveira, Aderbal C.; Souza, Paulo E.N. de [Institute of Physics, University of Brasília, 70910-900 Brasília, DF (Brazil); Franco Júnior, Adolfo [Institute of Physics, Federal University of Goiás, 74001-970 Goiânia, GO (Brazil)

    2015-07-15

    water surface when magnetic field is applied. This character was used successfully, by testing, for removal of small fraction vegetable oil on the water surface. - Graphical abstract: Display Omitted - Highlights: • Magnetic iron oxide synthesized by coprecipitation. • Magnetic iron oxide particles coated with polydimethylsiloxane. • Particles with hydrophobic and magnetic properties, which slide over the water surface.

  20. A Model for Predicting Magnetic Targeting of Multifunctional Particles in the Microvasculature

    CERN Document Server

    Furlani, E J

    2006-01-01

    A mathematical model is presented for predicting magnetic targeting of multifunctional carrier particles that are designed to deliver therapeutic agents to malignant tissue in vivo. These particles consist of a nonmagnetic core material that contains embedded magnetic nanoparticles and therapeutic agents such as photodynamic sensitizers. For in vivo therapy, the particles are injected into the vascular system upstream from malignant tissue, and captured at the tumor using an applied magnetic field. The applied field couples to the magnetic nanoparticles inside the carrier particle and produces a force that attracts the particle to the tumor. In noninvasive therapy the applied field is produced by a permanent magnet positioned outside the body. In this paper a mathematical model is developed for predicting noninvasive magnetic targeting of therapeutic carrier particles in the microvasculature. The model takes into account the dominant magnetic and fluidic forces on the particles and leads to an analytical expr...

  1. Magnetic particle imaging: current developments and future directions

    Directory of Open Access Journals (Sweden)

    Panagiotopoulos N

    2015-04-01

    Full Text Available Nikolaos Panagiotopoulos,1 Robert L Duschka,1 Mandy Ahlborg,2 Gael Bringout,2 Christina Debbeler,2 Matthias Graeser,2 Christian Kaethner,2 Kerstin Lüdtke-Buzug,2 Hanne Medimagh,2 Jan Stelzner,2 Thorsten M Buzug,2 Jörg Barkhausen,1 Florian M Vogt,1 Julian Haegele1 1Clinic for Radiology and Nuclear Medicine, University Hospital Schleswig Holstein, Campus Lübeck, 2Institute of Medical Engineering, University of Lübeck, Lübeck, Germany Abstract: Magnetic particle imaging (MPI is a novel imaging method that was first proposed by Gleich and Weizenecker in 2005. Applying static and dynamic magnetic fields, MPI exploits the unique characteristics of superparamagnetic iron oxide nanoparticles (SPIONs. The SPIONs’ response allows a three-dimensional visualization of their distribution in space with a superb contrast, a very high temporal and good spatial resolution. Essentially, it is the SPIONs’ superparamagnetic characteristics, the fact that they are magnetically saturable, and the harmonic composition of the SPIONs’ response that make MPI possible at all. As SPIONs are the essential element of MPI, the development of customized nanoparticles is pursued with the greatest effort by many groups. Their objective is the creation of a SPION or a conglomerate of particles that will feature a much higher MPI performance than nanoparticles currently available commercially. A particle’s MPI performance and suitability is characterized by parameters such as the strength of its MPI signal, its biocompatibility, or its pharmacokinetics. Some of the most important adjuster bolts to tune them are the particles’ iron core and hydrodynamic diameter, their anisotropy, the composition of the particles’ suspension, and their coating. As a three-dimensional, real-time imaging modality that is free of ionizing radiation, MPI appears ideally suited for applications such as vascular imaging and interventions as well as cellular and targeted imaging. A number

  2. Highly sensitive detection of protein biomarkers via nuclear magnetic resonance biosensor with magnetically engineered nanoferrite particles.

    Science.gov (United States)

    Jeun, Minhong; Park, Sungwook; Lee, Hakho; Lee, Kwan Hyi

    Magnetic-based biosensors are attractive for on-site detection of biomarkers due to the low magnetic susceptibility of biological samples. Here, we report a highly sensitive magnetic-based biosensing system that is composed of a miniaturized nuclear magnetic resonance (NMR) device and magnetically engineered nanoferrite particles (NFPs). The sensing performance, also identified as the transverse relaxation (R2) rate, of the NMR device is directly related to the magnetic properties of the NFPs. Therefore, we developed magnetically engineered NFPs (MnMg-NFP) and used them as NMR agents to exhibit a significantly improved R2 rate. The magnetization of the MnMg-NFPs was increased by controlling the Mn and Mg cation concentration and distribution during the synthesis process. This modification of the Mn and Mg cation directly contributed to improving the R2 rate. The miniaturized NMR system, combined with the magnetically engineered MnMg-NFPs, successfully detected a small amount of infectious influenza A H1N1 nucleoprotein with high sensitivity and stability.

  3. Magnetic separation of general solid particles realised by a permanent magnet

    Science.gov (United States)

    Hisayoshi, K.; Uyeda, C.; Terada, K.

    2016-12-01

    Most existing solids are categorised as diamagnetic or weak paramagnetic materials. The possibility of magnetic motion has not been intensively considered for these materials. Here, we demonstrate for the first time that ensembles of heterogeneous particles (diamagnetic bismuth, diamond and graphite particles, as well as two paramagnetic olivines) can be dynamically separated into five fractions by the low field produced by neodymium (NdFeB) magnets during short-duration microgravity (μg). This result is in contrast to the generally accepted notion that ordinary solid materials are magnetically inert. The materials of the separated particles are identified by their magnetic susceptibility (χ), which is determined from the translating velocity. The potential of this approach as an analytical technique is comparable to that of chromatography separation because the extraction of new solid phases from a heterogeneous grain ensemble will lead to important discoveries about inorganic materials. The method is applicable for the separation of the precious samples such as lunar soils and/or the Hayabusa particles recovered from the asteroids, because even micron-order grains can be thoroughly separated without sample-loss.

  4. Incrusting structure of nanosized Fe3O4 particles in magnetic fluids

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Jinsheng(张金升); YIN; Yansheng; (尹衍升); Lü; Yinong; (吕忆农); ZHANG; Yinyan; (张银燕); MA; Laipeng; (马来鹏); ZHANG; Shuqing; (张淑卿)

    2003-01-01

    High-performance nanosized Fe3O4 magnetic fluids are prepared by chemical co-pre- cipitate method. The microstructure of magnetic fluids is characterized using a transmission electron microscope (TEM) and high-resolution electron microscope (HREM). The results are satisfactory. The nanosized magnetic particles have diameter of 8-10 nm and the minimum diameter is 4 nm, belonging to super-paramagnetic material. The nanosized magnetic particles crystallized completely and have clear crystal boundary. The surfactant used in the test coats the magnetic particles homogeneously and forms a uniform and complete elastic spherical shell of amorphous phase around the magnetic particles. The study proves that the incrusting layer of surfactant has the protective effect and stable effect on the magnetic particles. These effects can enhance and maintain the magnetic properties of the magnetic fluids effectively.

  5. Nonaqueous magnetic nanoparticle suspensions with controlled particle size and nuclear magnetic resonance properties.

    Science.gov (United States)

    Meledandri, Carla J; Stolarczyk, Jacek K; Ghosh, Swapankumar; Brougham, Dermot F

    2008-12-16

    We report the preparation of monodisperse maghemite (gamma-Fe2O3) nanoparticle suspensions in heptane, by thermal decomposition of iron(III) acetylacetonate in the presence of oleic acid and oleylamine surfactants. By varying the surfactant/Fe precursor mole ratio during synthesis, control was exerted both over the nanocrystal core size, in the range from 3 to 6 nm, and over the magnetic properties of the resulting nanoparticle dispersions. We report field-cycling 1H NMR relaxation analysis of the superparamagnetic relaxation rate enhancement of nonaqueous suspensions for the first time. This approach permits measurement of the relaxivity and provides information on the saturation magnetization and magnetic anisotropy energy of the suspended particles. The saturation magnetization was found to be in the expected range for maghemite particles of this size. The anisotropy energy was found to increase significantly with decreasing particle size, which we attribute to increased shape anisotropy. This study can be used as a guide for the synthesis of maghemite nanoparticles with selected magnetic properties for a given application.

  6. Particles trajectories in Weibel magnetic filaments with a flow-aligned magnetic field

    CERN Document Server

    Bret, Antoine

    2016-01-01

    For a Weibel shock to form, two plasma shells have to collide and trigger the Weibel instability. At saturation, this instability generates in the overlapping region magnetic filaments with peak field $B_f$. In the absence of an external guiding magnetic field, these filaments can block the incoming flow, initiating the shock formation, if their size is larger than the Larmor radius of the incoming particles in the peak field. Here we show that this results still holds in the presence of an external magnetic field $B_0$, provided it is not too high. Yet, for $B_0 \\gtrsim B_f/2$, the filaments become unable to stop any particle, regardless of its initially velocity.

  7. Preparation and drug releasing property of magnetic chitosan-5-fluorouracil nano-particles

    Institute of Scientific and Technical Information of China (English)

    WANG Dong-sheng; LI Jian-guo; LI He-ping; TANG Fa-qing

    2009-01-01

    In order to synthesize the targeting drug carrier system, magnetic chitosan-5-fluorouracil nano-particles were prepared by using 5-fluorouracil (5-Fu) as model drug, Fe_3O_4 nano-particles as kernel, chitosan as enveloping material and glutaraldehyde as cross linking agent through ultrasonic technique. The morphology of the magnetic chitosan-5-Fu nano-particles was observed with a transmission electron microscope(TEM). The results showed that magnetic chitosan-5-Fu nano-particles were prepared in spherical structure with a size range of 50-60 nm. The delivering capacity and drug releasing properties of magnetic chitosan-5-Fu nano-particles were investigated by UV-vis spectrum analysis. The results showed that the loading capacity was 13.4% and the cumulative release percentage in the phosphate buffer (pH=7.2) solutions was 68% in 30 h. These data indicate that the wrapped drug of magnetic chitosan-5-Fu nano-particles was slowly-released. The magnetic response of magnetic chitosan-5-Fu nano-particles was studied by UV-vis spectrometer to detect the changes of solution absorbance. Without external magnetic field, the nano-particle deposition rate was slow. When being subjected to 8 mT magnetic field, the particle sedimentation rate was increased rapidly. The results showed that magnetic chitosan-5-Fu nano-particles have a magnetic stability and strong targeting characteristics.

  8. Preparation and characterization of magnetic levan particles as matrix for trypsin immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Maciel, J.C. [Programa de Pos-Graduacao em Ciencias Biologicas, Universidade Federal de Pernambuco, Cidade Universitaria, 50670-901 Recife, PE (Brazil); Andrad, P.L. [Programa de Pos-Graduacao em Ciencia de Materiais, Universidade Federal de Pernambuco, Cidade Universitaria, 50679-901 Recife, PE (Brazil); Neri, D.F.M., E-mail: davidfmneri@yahoo.com.br [Universidade Federal do Vale do Sao Francisco, 56304-205 Petrolina, PE (Brazil); Carvalho, L.B. [Departamento de Bioquimica, Universidade Federal de Pernambuco, Cidade Universitaria, 50679-901 Recife, PE (Brazil); Cardoso, C.A. [Departamento de Fisica, Universidade Federal de Sao Carlos, 13565-905 Sao Carlos, PE (Brazil); Calazans, G.M.T. [Departamento de Antibioticos, Universidade Federal de Pernambuco, Cidade Universitaria, 50670-901 Recife, PE (Brazil); Albino Aguiar, J. [Departamento de Fisica, Universidade Federal de Pernambuco, Cidade Universitaria, 50679-901 Recife, PE (Brazil); Silva, M.P.C. [Departamento de Bioquimica, Universidade Federal de Pernambuco, Cidade Universitaria, 50679-901 Recife, PE (Brazil)

    2012-04-15

    Magnetic levan was synthesized by co-precipitating D-fructofuranosyl homopolysaccharide with a solution containing Fe{sup 2+} and Fe{sup 3+} in alkaline conditions at 100 Degree-Sign C. The magnetic levan particles were characterized by scanning electron microscopy (SEM), magnetization measurements, X-ray diffractometry (XRD) and infrared spectroscopy (IR). Afterwards, magnetic levan particles were functionalized by NaIO{sub 4} oxidation and used as matrices for trypsin covalent immobilization. Magnetite and magnetic levan particles were both heterogeneous in shape and levan-magnetite presented bigger sizes compared to magnetite according to SEM images. Magnetic levan particles exhibited a magnetization 10 times lower as compared to magnetite ones, probably, due to the coating layer. XRD diffractogram showed that magnetite is the dominant phase in the magnetic levan. Infrared spectroscopy showed characteristics absorption bands of levan and magnetite (O-H, C-O-C and Fe-O bonds). The immobilized trypsin derivative was reused 10 times and lost 16% of its initial specific activity only. Therefore, these magnetic levan particles can be proposed as an alternative matrices for enzyme immobilization. - Highlights: Black-Right-Pointing-Pointer The magnetic levan particles presented larger size variation than magnetite particles due to the changes produced by coating. Black-Right-Pointing-Pointer The utilization of magnetic levan particles showed to be efficacious for immobilization of enzymes as trypsin. Black-Right-Pointing-Pointer Magnetic particles can be planned as other matrix for immobilization of biomolecule in various division processes in biotechnology.

  9. Magnetic particle imaging: from proof of principle to preclinical applications

    Science.gov (United States)

    Knopp, T.; Gdaniec, N.; Möddel, M.

    2017-07-01

    Tomographic imaging has become a mandatory tool for the diagnosis of a majority of diseases in clinical routine. Since each method has its pros and cons, a variety of them is regularly used in clinics to satisfy all application needs. Magnetic particle imaging (MPI) is a relatively new tomographic imaging technique that images magnetic nanoparticles with a high spatiotemporal resolution in a quantitative way, and in turn is highly suited for vascular and targeted imaging. MPI was introduced in 2005 and now enters the preclinical research phase, where medical researchers get access to this new technology and exploit its potential under physiological conditions. Within this paper, we review the development of MPI since its introduction in 2005. Besides an in-depth description of the basic principles, we provide detailed discussions on imaging sequences, reconstruction algorithms, scanner instrumentation and potential medical applications.

  10. Simulated annealing: an application in fine particle magnetism

    Energy Technology Data Exchange (ETDEWEB)

    Legeratos, A.; Chantrell, R.W.; Wohlfarth, E.P.

    1985-07-01

    Using a model of a system of interacting fine ferromagnetic particles, a computer simulation of the dynamical approach to local or global minima of the system is developed for two different schedules of the application of ac and dc magnetic fields. The process of optimization, i.e., the achievement of a global minimum, depends on the rate of reduction of the ac field and on the symmetry of the ac field cycles. The calculations carried out to illustrate these effects include remanence curves and the zero field remanence for both schedules under different conditions. The growth of the magnetization during these processes was studied, and the interaction energy was calculated to best illustrate the optimization.

  11. Motion of test particles in a magnetized conformastatic background

    CERN Document Server

    Gutiérrez-Piñeres, Antonio C

    2015-01-01

    A class of exact conformastatic solutions of the Einstein-Maxwell field equations is presented in which the gravitational and electromagnetic potentials are completely determined by a harmonic function only. The motion of test particles is investigated in the background of a space-time characterized by this class of solutions. We focus on the study of circular stable and unstable orbits obtained by taking account particular harmonic functions defining the gravitational potential. We show that is possible to have repulsive force generated by the charge distribution of the source. As the space-time here considered is singularity free we conclude that this phenomena is not exclusive to the case of naked singularities. Additionally, we obtain an expression for the perihelion advance of the test particles in a general magnetized conformastatic space-time.

  12. Simulating Magnetized Laboratory Plasmas with Smoothed Particle Hydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Jeffrey N. [Univ. of California, Davis, CA (United States)

    2009-01-01

    The creation of plasmas in the laboratory continues to generate excitement in the physics community. Despite the best efforts of the intrepid plasma diagnostics community, the dynamics of these plasmas remains a difficult challenge to both the theorist and the experimentalist. This dissertation describes the simulation of strongly magnetized laboratory plasmas with Smoothed Particle Hydrodynamics (SPH), a method born of astrophysics but gaining broad support in the engineering community. We describe the mathematical formulation that best characterizes a strongly magnetized plasma under our circumstances of interest, and we review the SPH method and its application to astrophysical plasmas based on research by Phillips [1], Buerve [2], and Price and Monaghan [3]. Some modifications and extensions to this method are necessary to simulate terrestrial plasmas, such as a treatment of magnetic diffusion based on work by Brookshaw [4] and by Atluri [5]; we describe these changes as we turn our attention toward laboratory experiments. Test problems that verify the method are provided throughout the discussion. Finally, we apply our method to the compression of a magnetized plasma performed by the Compact Toroid Injection eXperiment (CTIX) [6] and show that the experimental results support our computed predictions.

  13. GEMPIC: Geometric ElectroMagnetic Particle-In-Cell Methods

    CERN Document Server

    Kraus, Michael; Morrison, Philip J; Sonnendrücker, Eric

    2016-01-01

    We present a novel framework for Finite Element Particle-in-Cell methods based on the discretization of the underlying Hamiltonian structure of the Vlasov-Maxwell system. We derive a semi-discrete Poisson bracket, which satisfies the Jacobi identity , and apply Hamiltonian splitting schemes for time integration. Techniques from Finite Element Exterior Calculus ensure conservation of the divergence of the magnetic field and Gauss' law as well as stability of the field solver. The resulting methods are gauge-invariant, feature exact charge conservation and show excellent long-time energy and momentum behavior.

  14. Magnetic geometry and particle source drive of supersonic divertor regimes

    Science.gov (United States)

    Bufferand, H.; Ciraolo, G.; Dif-Pradalier, G.; Ghendrih, P.; Tamain, Ph; Marandet, Y.; Serre, E.

    2014-12-01

    We present a comprehensive picture of the mechanisms driving the transition from subsonic to supersonic flows in tokamak plasmas. We demonstrate that supersonic parallel flows into the divertor volume are ubiquitous at low density and governed by the divertor magnetic geometry. As the density is increased, subsonic divertor plasmas are recovered. On detachment, we show the change in particle source can also drive the transition to a supersonic regime. The comprehensive theoretical analysis is completed by simulations in ITER geometry. Such results are essential in assessing the divertor performance and when interpreting measurements and experimental evidence.

  15. Competition of magnetic and hydrodynamic forces on ellipsoidal particles under shear: Influence of the Earth's magnetic field on particle alignment in viscous media

    Science.gov (United States)

    Jezek, Josef; Gilder, Stuart A.

    2006-12-01

    We present a model that describes the rotation of ellipsoidal magnetic particles in a viscous fluid under the influence of hydrodynamic and magnetic forces, with an aim to better understand how sediments acquire their remanent magnetizations. Analyses of the governing equations elucidate how magnetic particles will rotate for different values of leading parameters including particle shape, remanent and induced magnetic intensity, magnetic field intensity and direction, strain rate, shear direction, and viscosity. Numerical solution of the governing equations makes it possible to visualize the rotation path and the magnetic direction of a particle through time. Thus the model can discern the timescales and trajectories of magnetic particles rotating due to torque of the magnetic field couple while simultaneously entrained in a velocity gradient. For example, in a layer of viscosity 104 Pa s, prolate magnetite starting at any initial orientation and subjected to simple shear with a strain rate of 3.17 × 10-8 s-1 needs 4 months to rotate within 3° of the Earth's field direction. Under the same conditions, hydrodynamic forces will govern the orientation of oblate hematite whose moment will be perpetually randomly oriented with respect to the magnetic field direction. When applied to laboratory experiments, the viscous model successfully matches the observed data, particularly after accounting for mechanical interaction and flocculation effects. Magnetic anisotropies calculated from multiparticle systems of hematite yield typical sedimentary fabrics with relatively low percentages of anisotropy (<5%) and maximum principal axes that lie in the sedimentation plane.

  16. Aggregation process of paramagnetic particles in fluid in the magnetic field.

    Science.gov (United States)

    Pei, Ning; Cheng, Xiaoye; Huang, Zheyong; Wang, Xiang; Yang, Kai; Wang, Ye; Gong, Yongyong

    2016-07-01

    Magnetic targeting is a promising therapeutic strategy for localizing systemically delivered magnetic responsive drugs or cells to target tissue, but excessive aggregation of magnetic particles could result in vascular embolization. To analyze the reason for embolization, the attractive process of magnetic particles in magnetic field (MF) was studied in this paper by analyzing the form of the aggregated paramagnetic particles while the particle suspension flowed through a tube, which served as a model of blood vessels. The effects of magnetic flux density and fluid velocity on the formation of aggregated paramagnetic particles were investigated. The number of large aggregated clusters dramatically increased with increment in the magnetic flux density and decreased with increment in the fluid velocity. The analysis of accumulative process demonstrates the MF around initially attracted particles was focused, which induced the formation of clusters and increased the possibility of embolism. Bioelectromagnetics. 37:323-330, 2016. © 2016 Wiley Periodicals, Inc.

  17. Magnetic separation of particles and cells in ferrofluid flow through a straight microchannel using two offset magnets

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Jian; Deng, Yanxiang [Department of Mechanical Engineering, Clemson University, Clemson, SC 29634-0921 (United States); Vedantam, Pallavi; Tzeng, Tzuen-Rong [Department of Biological Sciences, Clemson University, Clemson, SC 29634-0314 (United States); Xuan, Xiangchun, E-mail: xcxuan@clemson.edu [Department of Mechanical Engineering, Clemson University, Clemson, SC 29634-0921 (United States)

    2013-11-15

    The separation of particles and cells is critical in many chemical and biological applications. This work presents a simple idea for utilizing a pair of permanent magnets to continuously separate diamagnetic particles and cells in ferrofluid flow through a straight microchannel. The first magnet is placed close to the microchannel for focusing the particle mixture to a single stream without the use of a sheath flow. The second magnet, which is offset from the first magnet and placed farther from the channel, is to displace the aligned particles to dissimilar flow paths for a continuous sorting. This idea is first demonstrated through the separation of 3 μm- and 10 μm-diameter polystyrene particles, where the effects of flow speed and magnet distance are both examined. The experimental data are found to fit well with the predictions of an analytical model. Furthermore, a continuous separation of live yeast cells from 10 μm polystyrene particles is implemented in the same device. - Highlights: • We develop a simple diamagnetic particle and cell separation technique in ferrofluids. • Two offset magnets are used to achieve a sheath-free continuous separation in a straight microchannel. • The technique is demonstrated through the magnetic separation of polystyrene particles and yeast cells. • The effects of ferrofluid speed and magnet-channel distance are examined on particle separation. • The predictions from an analytical model agree with the experimental data quantitatively.

  18. Simultaneous bioassays in a microfluidic channel on plugs of different magnetic particles.

    Science.gov (United States)

    Bronzeau, Sandrine; Pamme, Nicole

    2008-02-18

    Magnetic particles coated with specific biomolecules are often used as solid supports for bioassays but conventional test tube based techniques are time consuming and labour intensive. An alternative is to work on magnetic particle plugs immobilised inside microfluidic channels. Most research so far has focussed on immobilising one type of particle to perform one type of assay. Here we demonstrate how several assays can be performed simultaneously by flushing a sample solution over several plugs of magnetic particles with different surface coatings. Within a microchannel, three plugs of magnetic particles were immobilised with external magnets. The particles featured surface coatings of glycine, streptavidin and protein A, respectively. Reagents were then flushed through the three plugs. Molecular binding occurred between matching antigens and antibodies in continuous flow and was detected by fluorescence. This first demonstration opens the door to a quicker and easier technique for simultaneous bioassays using magnetic particles.

  19. Magnetic study of M-type doped barium hexaferrite nanocrystalline particles

    Energy Technology Data Exchange (ETDEWEB)

    Alsmadi, A. M., E-mail: abdel.alsmadi@ku.edu.kw [Physics Department, Kuwait University, 13060 Safat (Kuwait); Physics Department, The Hashemite University, 13115 Zarqa (Jordan); Bsoul, I. [Physics Department, Al al-Bayt University, Mafraq (Jordan); Mahmood, S. H. [Physics Department, The University of Jordan, Amman (Jordan); Alnawashi, G. [Physics Department, The Hashemite University, 13115 Zarqa (Jordan); Prokeš, K.; Siemensmeyer, K.; Klemke, B. [Helmholtz Zentrum für Matearialien und Energie, 14109 Berlin (Germany); Nakotte, H. [Physics Department, New Mexico State University, Las Cruces, New Mexico 88003 (United States)

    2013-12-28

    Co-Ti and Ru-Ti substituted barium ferrite nanocrystalline particles BaFe{sub 12−2x}Co{sub x}Ti{sub x}O{sub 19} with (0≤x≤1) and BaFe{sub 12−2x}Ru{sub x}Ti{sub x}O{sub 19} with (0≤x≤0.6) were prepared by ball milling method, and their magnetic properties and their temperature dependencies were studied. The zero-field-cooled (ZFC) and field-cooled (FC) processes were recorded at low magnetic fields and the ZFC curves displayed a broad peak at a temperature T{sub M}. In all samples under investigation, a clear irreversibility between the ZFC and FC curves was observed below room temperature, and this irreversibility disappeared above room temperature. These results were discussed within the framework of random particle assembly model and associated with the magnetic domain wall motion. The resistivity data showed some kind of a transition from insulator to perfect insulator around T{sub M}. At 2 K, the saturation magnetization slightly decreased and the coercivity dropped dramatically with increasing the Co-Ti concentration x. With Ru-Ti substitution, the saturation magnetization showed small variations, while the coercivity decreased monotonically, recording a reduction of about 73% at x = 0.6. These results were discussed in light of the single ion anisotropy model and the cationic distributions based on previously reported neutron diffraction data for the CoTi substituted system, and the results of our Mössbauer spectroscopy data for the RuTi substituted system.

  20. Separation of two attractive ferromagnetic ellipsoidal particles by hydrodynamic interactions under alternating magnetic field

    Science.gov (United States)

    Abbas, Micheline; Bossis, Georges

    2017-06-01

    In applications where magnetic particles are used to detect and dose targeted molecules, it is of major importance to prevent particle clustering and aggregation during the capture stage in order to maximize the capture rate. Elongated ferromagnetic particles can be more interesting than spherical ones due to their large magnetic moment, which facilitates their separation by magnets or the detection by optical measurement of their orientation relaxation time. Under alternating magnetic field, the rotational dynamics of elongated ferromagnetic particles results from the balance between magnetic torque that tends to align the particle axis with the field direction and viscous torque. As for their translational motion, it results from a competition between direct magnetic particle-particle interactions and solvent-flow-mediated hydrodynamic interactions. Due to particle anisotropy, this may lead to intricate translation-rotation couplings. Using numerical simulations and theoretical modeling of the system, we show that two ellipsoidal magnetic particles, initially in a head-to-tail attractive configuration resulting from their remnant magnetization, can repel each other due to hydrodynamic interactions when alternating field is operated. The separation takes place in a range of low frequencies fc 1magnetic field to particle magnetization strength, whereas fc 1 tends to zero when this ratio increases.

  1. Particle Acceleration and Plasma Dynamics during Magnetic Reconnection in the Magnetically-dominated Regime

    CERN Document Server

    Guo, Fan; Daughton, William; Li, Hui

    2015-01-01

    Magnetic reconnection is thought to be the driver for many explosive phenomena in the universe. The energy release and particle acceleration during reconnection have been proposed as a mechanism for producing high-energy emissions and cosmic rays. We carry out two- and three-dimensional kinetic simulations to investigate relativistic magnetic reconnection and the associated particle acceleration. The simulations focus on electron-positron plasmas starting with a magnetically dominated, force-free current sheet ($\\sigma \\equiv B^2/(4\\pi n_e m_e c^2) \\gg 1$). For this limit, we demonstrate that relativistic reconnection is highly efficient at accelerating particles through a first-order Fermi process accomplished by the curvature drift of particles along the electric field induced by the relativistic flows. This mechanism gives rise to the formation of hard power-law spectra $f \\propto (\\gamma-1)^{-p}$ and approaches $p = 1$ for sufficiently large $\\sigma$ and system size. Eventually most of the available magne...

  2. Plasmonic nanoantennas for multipurpose particle manipulation and enhanced optical magnetism

    Science.gov (United States)

    Roxworthy, Brian James

    surface, likely by means of fs-augmented near-field gradient forces. Using this particle-fusing behavior as inspiration, a novel class of "capped" nanoantennas is designed, and their plasmonic response is theoretically investigated. The specific example of capped-bowtie nanoantennas (c-BNAs) is chosen, and it is shown that the c-BNAs have the unique ability to simultaneously enhance both magnetic and electric fields by more than three and four orders of magnitude, respectively. This ability improves on currently available designs that enhance magnetic fields at the expense of a mitigated electric response. The spectral response of the c-BNAs is dominated by two distinct resonant peaks: one in the visible (VIS) and one in the near-infrared (NIR), and the spectral behavior of the c-BNAs is examined as a function of cap thickness, bowtie gap spacing, and c-BNA array spacing. Finally, a new pillar-bowtie nanoantenna (p-BNA) design, comprising Au BNA arrays suspended on 500 nm tall SiO2 pillars, is introduced as a candidate system to show, for the first time, that the mechanical degree of freedom (DOF) can be used to create in situ reconfigurable plasmonic nanoantennas. Reconfigurability is achieved using electron-beam manipulation in a scanning electron microscope (SEM), whereby the electron beam induces strong electromagnetic gradient forces in the p-BNA gap that causes the two arms to deform toward the common gap center. In characterizing this behavior as a function of SEM accelerating voltage and magnification, design curves are produced that enable controlled, repeatable fabrication of nanoantennas with gap sizes as small as 5 nm by actuation of the mechanical DOF of the pillars. As a proof of this novel design principle, the optical response of two, 10 x 10 modified p-BNA regions comprising 5- and 15-nm gap antennas is characterized using spatially localized reflection spectroscopy based on a supercontinuum optical source. (Abstract shortened by UMI.).

  3. Relaxation-based viscosity mapping for magnetic particle imaging

    Science.gov (United States)

    Utkur, M.; Muslu, Y.; Saritas, E. U.

    2017-05-01

    Magnetic particle imaging (MPI) has been shown to provide remarkable contrast for imaging applications such as angiography, stem cell tracking, and cancer imaging. Recently, there is growing interest in the functional imaging capabilities of MPI, where ‘color MPI’ techniques have explored separating different nanoparticles, which could potentially be used to distinguish nanoparticles in different states or environments. Viscosity mapping is a promising functional imaging application for MPI, as increased viscosity levels in vivo have been associated with numerous diseases such as hypertension, atherosclerosis, and cancer. In this work, we propose a viscosity mapping technique for MPI through the estimation of the relaxation time constant of the nanoparticles. Importantly, the proposed time constant estimation scheme does not require any prior information regarding the nanoparticles. We validate this method with extensive experiments in an in-house magnetic particle spectroscopy (MPS) setup at four different frequencies (between 250 Hz and 10.8 kHz) and at three different field strengths (between 5 mT and 15 mT) for viscosities ranging between 0.89 mPa · s-15.33 mPa · s. Our results demonstrate the viscosity mapping ability of MPI in the biologically relevant viscosity range.

  4. Design and validation of magnetic particle spectrometer for characterization of magnetic nanoparticle relaxation dynamics

    Directory of Open Access Journals (Sweden)

    Nicolas Garraud

    2017-05-01

    Full Text Available The design and validation of a magnetic particle spectrometer (MPS system used to study the linear and nonlinear behavior of magnetic nanoparticle suspensions is presented. The MPS characterizes the suspension dynamic response, both due to relaxation and saturation effects, which depends on the magnetic particles and their environment. The system applies sinusoidal excitation magnetic fields varying in amplitude and frequency and can be configured for linear measurements (1 mT at up to 120 kHz and nonlinear measurements (50 mT at up to 24 kHz. Time-resolved data acquisition at up to 4 MS/s combined with hardware and software-based signal processing allows for wide-band measurements up to 50 harmonics in nonlinear mode. By cross-calibrating the instrument with a known sample, the instantaneous sample magnetization can be quantitatively reconstructed. Validation of the two MPS modes are performed for iron oxide and cobalt ferrite suspensions, exhibiting Néel and Brownian relaxation, respectively.

  5. Slew-rate dependence of tracer magnetization response in magnetic particle imaging.

    Science.gov (United States)

    Shah, Saqlain A; Ferguson, R M; Krishnan, K M

    2014-10-28

    Magnetic Particle Imaging (MPI) is a new biomedical imaging technique that produces real-time, high-resolution tomographic images of superparamagnetic iron oxide nanoparticle tracers. Currently, 25 kHz and 20 mT/μ0 excitation fields are common in MPI, but lower field amplitudes may be necessary for patient safety in future designs. Here, we address fundamental questions about MPI tracer magnetization dynamics and predict tracer performance in future scanners that employ new combinations of excitation field amplitude (Ho ) and frequency (ω). Using an optimized, monodisperse MPI tracer, we studied how several combinations of drive field frequencies and amplitudes affect the tracer's response, using Magnetic Particle Spectrometry and AC hysteresis, for drive field conditions at 15.5, 26, and 40.2 kHz, with field amplitudes ranging from 7 to 52 mT/μ0. For both fluid and immobilized nanoparticle samples, we determined that magnetic response was dominated by Néel reversal. Furthermore, we observed that the peak slew-rate (ωHo) determined the tracer magnetic response. Smaller amplitudes provided correspondingly smaller field of view, sometimes resulting in excitation of minor hysteresis loops. Changing the drive field conditions but keeping the peak slew-rate constant kept the tracer response almost the same. Higher peak slew-rates led to reduced maximum signal intensity and greater coercivity in the tracer response. Our experimental results were in reasonable agreement with Stoner-Wohlfarth model based theories.

  6. Effects of Magnetic Particles Entrance Arrange-ments on Mixing Efficiency of a Magnetic Bead Micromixer

    Institute of Scientific and Technical Information of China (English)

    Reza Kamali∗; Seyed Alireza Shekoohi; Alireza Binesh

    2014-01-01

    In this study, a computer code is developed to numerically investigate a magnetic bead micromixer under different conditions. The micromixer consists of a microchannel and numerous micro magnetic particles which enter the micromixer by fluid flows and are actuated by an alternating magnetic field normal to the main flow. An important feature of micromixer which is not considered before by researchers is the particle entrance arrangement into the micromixer. This parameter could effectively affect the micromixer efficiency. There are two general micro magnetic particle entrance arrangements in magnetic bead micromixers: determined position entrance and random position entrance. In the case of determined position entrances, micro magnetic particles enter the micromixer at specific positions of entrance cross section. However, in a random position entrance, particles enter the microchannel with no order. In this study mixing efficiencies of identical magnetic bead micromixers which only differ in particle entrance arrangement are numerically investigated and compared. The results reported in this paper illustrate that the prepared computer code can be one of the most powerful and beneficial tools for the magnetic bead micromixer performance analysis. In addition, the results show that some features of the magnetic bead micromixer are strongly affected by the entrance arrangement of the particles.

  7. Intracellular performance of tailored nanoparticle tracers in magnetic particle imaging

    Energy Technology Data Exchange (ETDEWEB)

    Arami, Hamed; Krishnan, Kannan M., E-mail: kannanmk@uw.edu [Department of Materials Science and Engineering, University of Washington, P.O. Box 352120, Seattle, Washington 98195-2120 (United States)

    2014-05-07

    Magnetic Particle Imaging (MPI) is a quantitative mass-sensitive, tracer-based imaging technique, with potential applications in various cellular imaging applications. The spatial resolution of MPI, in the first approximation, improves by decreasing the full width at half maximum (FWHM) of the field-derivative of the magnetization, dm/dH of the nanoparticle (NP) tracers. The FWHM of dm/dH depends critically on NPs’ size, size distribution, and their environment. However, there is limited information on the MPI performance of the NPs after their internalization into cells. In this work, 30 to 150 μg of the iron oxide NPs were incubated in a lysosome-like acidic buffer (0.2 ml, 20 mM citric acid, pH 4.7) and investigated by vibrating sample magnetometry, magnetic particle spectroscopy, transmission electron microscopy, and dynamic light scattering (DLS). The FWHM of the dm/dH curves of the NPs increased with incubation time and buffer to NPs ratio, consistent with a decrease in the median core size of the NPs from ∼20.1 ± 0.98 to ∼18.5 ± 3.15 nm. Further, these smaller degraded NPs formed aggregates that responded to the applied field by hysteretic reversal at higher field values and increased the FWHM. The rate of core size decrease and aggregation were inversely proportional to the concentration of the incubated NPs, due to their slower biodegradation kinetics. The results of this model experiment show that the MPI performance of the NPs in the acidic environments of the intracellular organelles (i.e., lysosomes and endosomes) can be highly dependent on their rate of internalization, residence time, and degradation.

  8. Micro-magnetic particles frit for capillary electrochromatography.

    Science.gov (United States)

    Oguri, Shigeyuki; Oga, Chiari; Takeda, Haruna

    2007-07-20

    This paper presents a new method for making frit using soft-ferrite-based micro-magnetic particles (MMPs) in a micro-space, such as in a capillary tube. The MMPs-frit was made by injecting an aliquot of 10 microm (outer diameter; o.d.)-MMPs-suspension in methanol (ca. 1mg/ml) into a capillary tube (75 microm inner diameter (i.d.) x 375 microm o.d. x ca. 35 cm length) that was already sandwiched between a pair of cylindrical Neodium (Nd-Fe-B) magnets (1.5 mm o.d. x 1.5 mm height, 280 mT) at a position where the frit was made. The MMPs were trapped in the capillary tube as a frit due to the attraction of the magnets placed at surface on the capillary tube. With regard to durability, the frit was stable for methanol flow with a flow rate of 400 microl/min at room temperature. Using such a frit, a capillary column (20 cm long) was prepared by injecting a 5 microm (o.d.)-ODS-particle suspension in methanol (ca. 0.4 mg/microl) into the capillary tube. The MMPs-frits-ODS-packed column was stable for methanol for a flow pressure less than 20MPa. When comparing the present column with a conventional sintered-frits-ODS-packed column for the purposes of separating five kinds of biogenic amines by means of an on-column derivatization capillary electrochromatography (CEC), the performance of the MMPs-frits capillary column was almost equivalent to that of the sintered-frits-ODS-packed column.

  9. Intracellular performance of tailored nanoparticle tracers in magnetic particle imaging.

    Science.gov (United States)

    Arami, Hamed; Krishnan, Kannan M

    2014-05-07

    Magnetic Particle Imaging (MPI) is a quantitative mass-sensitive, tracer-based imaging technique, with potential applications in various cellular imaging applications. The spatial resolution of MPI, in the first approximation, improves by decreasing the full width at half maximum (FWHM) of the field-derivative of the magnetization, dm/dH of the nanoparticle (NP) tracers. The FWHM of dm/dH depends critically on NPs' size, size distribution, and their environment. However, there is limited information on the MPI performance of the NPs after their internalization into cells. In this work, 30 to 150 μg of the iron oxide NPs were incubated in a lysosome-like acidic buffer (0.2 ml, 20 mM citric acid, pH 4.7) and investigated by vibrating sample magnetometry, magnetic particle spectroscopy, transmission electron microscopy, and dynamic light scattering (DLS). The FWHM of the dm/dH curves of the NPs increased with incubation time and buffer to NPs ratio, consistent with a decrease in the median core size of the NPs from ∼20.1 ± 0.98 to ∼18.5 ± 3.15 nm. Further, these smaller degraded NPs formed aggregates that responded to the applied field by hysteretic reversal at higher field values and increased the FWHM. The rate of core size decrease and aggregation were inversely proportional to the concentration of the incubated NPs, due to their slower biodegradation kinetics. The results of this model experiment show that the MPI performance of the NPs in the acidic environments of the intracellular organelles (i.e., lysosomes and endosomes) can be highly dependent on their rate of internalization, residence time, and degradation.

  10. Simulation of magnetic drug targeting through tracheobronchial airways in the presence of an external non-uniform magnetic field using Lagrangian magnetic particle tracking

    Energy Technology Data Exchange (ETDEWEB)

    Pourmehran, O., E-mail: oveis87@yahoo.com; Rahimi-Gorji, M.; Gorji-Bandpy, M., E-mail: gorji@nit.ac.ir; Gorji, T.B.

    2015-11-01

    Drug delivery technologies are an important area within biomedicine. Targeted drug delivery aims to reduce the undesired side effects of drug usage by directing or capturing the active agents near a desired site within the body. Herein, a numerical investigation of magnetic drug targeting (MDT) using aerosol drugs named polystyrene particle (PMS40) in human lung is presented considering one-way coupling on the transport and capture of the magnetic particle. A realistic 3D geometry based on CT scan images is provided for CFD simulation. An external non-uniform magnetic field is applied. Parametric investigation is conducted and the influence of particle diameter, magnetic source position, and magnetic number (Mn) on the deposition efficiency and particle behavior is reported. According to the results, the magnetic field increased deposition efficiency of particles in a target region, the efficiency of deposition and MDT technique has a direct relation with increasing the particle diameter for magnetic number of 1 Tesla (T) and lower (Mn≤1(T)). Also it can be seen that there is an inverse relation between the particle diameter and deposition efficiency when Mn is more than 1 (T). - Highlights: • A realistic 3D geometry of human tracheobronchial airway based on CT scan image. • External non-uniform magnetic field applied to target the magnetic drug career. • Lagrangian particle tracking using discrete phase model applied. • The efficiency of deposition is dependent of magnetic number and particle diameter.

  11. Relaxation in x-space magnetic particle imaging.

    Science.gov (United States)

    Croft, Laura R; Goodwill, Patrick W; Conolly, Steven M

    2012-12-01

    Magnetic particle imaging (MPI) is a new imaging modality that noninvasively images the spatial distribution of superparamagnetic iron oxide nanoparticles (SPIOs). MPI has demonstrated high contrast and zero attenuation with depth, and MPI promises superior safety compared to current angiography methods, X-ray, computed tomography, and magnetic resonance imaging angiography. Nanoparticle relaxation can delay the SPIO magnetization, and in this work we investigate the open problem of the role relaxation plays in MPI scanning and its effect on the image. We begin by amending the x-space theory of MPI to include nanoparticle relaxation effects. We then validate the amended theory with experiments from a Berkeley x-space relaxometer and a Berkeley x-space projection MPI scanner. Our theory and experimental data indicate that relaxation reduces SNR and asymmetrically blurs the image in the scanning direction. While relaxation effects can have deleterious effects on the MPI scan, we show theoretically and experimentally that x-space reconstruction remains robust in the presence of relaxation. Furthermore, the role of relaxation in x-space theory provides guidance as we develop methods to minimize relaxation-induced blurring. This will be an important future area of research for the MPI community.

  12. Design of superparamagnetic nanoparticles for magnetic particle imaging (MPI).

    Science.gov (United States)

    Du, Yimeng; Lai, Pui To; Leung, Cheung Hoi; Pong, Philip W T

    2013-09-11

    Magnetic particle imaging (MPI) is a promising medical imaging technique producing quantitative images of the distribution of tracer materials (superparamagnetic nanoparticles) without interference from the anatomical background of the imaging objects (either phantoms or lab animals). Theoretically, the MPI platform can image with relatively high temporal and spatial resolution and sensitivity. In practice, the quality of the MPI images hinges on both the applied magnetic field and the properties of the tracer nanoparticles. Langevin theory can model the performance of superparamagnetic nanoparticles and predict the crucial influence of nanoparticle core size on the MPI signal. In addition, the core size distribution, anisotropy of the magnetic core and surface modification of the superparamagnetic nanoparticles also determine the spatial resolution and sensitivity of the MPI images. As a result, through rational design of superparamagnetic nanoparticles, the performance of MPI could be effectively optimized. In this review, the performance of superparamagnetic nanoparticles in MPI is investigated. Rational synthesis and modification of superparamagnetic nanoparticles are discussed and summarized. The potential medical application areas for MPI, including cardiovascular system, oncology, stem cell tracking and immune related imaging are also analyzed and forecasted.

  13. Microcapillary flow behavior of magnetic nanofluids in the presence of plate shaped bentonite particles

    Energy Technology Data Exchange (ETDEWEB)

    Parmar, Mayur; Virpura, Hiral [Department of Physics, Bhavnagar University, Bhavnagar 364001, GJ (India); Patel, Rajesh, E-mail: rjp@bhavuni.edu [Department of Physics, Bhavnagar University, Bhavnagar 364001, GJ (India); Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States)

    2013-04-15

    Plate shaped bentonite particles of size ∼600 nm and thickness ∼2 nm are dispersed in a magnetic nanofluid. Magnetic field dependent flow behavior of this composite suspension is studied using a horizontal microcapillary placed between the poles of an electromagnet. The plate shaped bentonite particle produces extra hindrance to the flow under the application of moderate magnetic field and produces an enhanced magnetoviscous effect. 75% volume concentration of bentonite produces eight times larger change in magnetic field dependent viscosity than does the pure magnetic nanofluid. Hindrance to the flow is due to the chain like structure of magnetic nanoparticles, tumbling and rotational motion of bentonite particles and interaction between magnetic and bentonite particles. The field-induced structures are also observed using an optical microscope. Results offer several advantages over the inverse MR effect as well as to study the motion of biological cells and tissues under the effect of magnetic field. -- Highlights: ► Dispersed plate shaped bentonite particles in magnetic fluids to study capillary viscosity. ► Increased viscosity is due to the hindrance to the rotation of the bentonite particles. ► Increase in viscosity is five times larger for bentonite particles than the pure magnetic fluids. ► This is a new kind of magnetoviscous effect, dispersing anisotropic particles in magnetic fluids.

  14. Particle Capture Efficiency in a Multi-Wire Model for High Gradient Magnetic Separation

    CERN Document Server

    Eisenträger, Almut; Griffiths, Ian M

    2014-01-01

    High gradient magnetic separation (HGMS) is an efficient way to remove magnetic and paramagnetic particles, such as heavy metals, from waste water. As the suspension flows through a magnetized filter mesh, high magnetic gradients around the wires attract and capture the particles, removing them from the fluid. We model such a system by considering the motion of a paramagnetic tracer particle through a periodic array of magnetized cylinders. We show that there is a critical Mason number (ratio of viscous to magnetic forces) below which the particle is captured irrespective of its initial position in the array. Above this threshold, particle capture is only partially successful and depends on the particle's entry position. We determine the relationship between the critical Mason number and the system geometry using numerical and asymptotic calculations. If a capture efficiency below 100% is sufficient, our results demonstrate how operating the HGMS system above the critical Mason number but with multiple separa...

  15. Enhancement of iron content in spinach plants stimulated by magnetic nano particles

    Science.gov (United States)

    Yulianto, Agus; Astuti, Budi; Amalia, Saptaria Rosa

    2016-04-01

    In our previous study, the iron content in spinach plants could be detected by magnetic susceptibility values. In the present work, magnetic nano particles were found from the iron sand. The magnetic nano particles are synthesis by using co-precipitation process and sol-gel technique. The stimulation of magnetic nano particles in the plant has been done by the provision of magnetic nano particles in growing media. After certain time, plant samples was characterized using susceptibility-meter MS2B and atomic absorption spectroscopy to measure the magnetic susceptibility and the amount of iron content that absorbed of the plant, respectively. The iron content in the spinach plants was increased when the magnetic nano particles was injected in the growing media.

  16. Encouragement of Enzyme Reaction Utilizing Heat Generation from Ferromagnetic Particles Subjected to an AC Magnetic Field.

    Science.gov (United States)

    Suzuki, Masashi; Aki, Atsushi; Mizuki, Toru; Maekawa, Toru; Usami, Ron; Morimoto, Hisao

    2015-01-01

    We propose a method of activating an enzyme utilizing heat generation from ferromagnetic particles under an ac magnetic field. We immobilize α-amylase on the surface of ferromagnetic particles and analyze its activity. We find that when α-amylase/ferromagnetic particle hybrids, that is, ferromagnetic particles, on which α-amylase molecules are immobilized, are subjected to an ac magnetic field, the particles generate heat and as a result, α-amylase on the particles is heated up and activated. We next prepare a solution, in which α-amylase/ferromagnetic particle hybrids and free, nonimmobilized chitinase are dispersed, and analyze their activities. We find that when the solution is subjected to an ac magnetic field, the activity of α-amylase immobilized on the particles increases, whereas that of free chitinase hardly changes; in other words, only α-amylase immobilized on the particles is selectively activated due to heat generation from the particles.

  17. Encouragement of Enzyme Reaction Utilizing Heat Generation from Ferromagnetic Particles Subjected to an AC Magnetic Field.

    Directory of Open Access Journals (Sweden)

    Masashi Suzuki

    Full Text Available We propose a method of activating an enzyme utilizing heat generation from ferromagnetic particles under an ac magnetic field. We immobilize α-amylase on the surface of ferromagnetic particles and analyze its activity. We find that when α-amylase/ferromagnetic particle hybrids, that is, ferromagnetic particles, on which α-amylase molecules are immobilized, are subjected to an ac magnetic field, the particles generate heat and as a result, α-amylase on the particles is heated up and activated. We next prepare a solution, in which α-amylase/ferromagnetic particle hybrids and free, nonimmobilized chitinase are dispersed, and analyze their activities. We find that when the solution is subjected to an ac magnetic field, the activity of α-amylase immobilized on the particles increases, whereas that of free chitinase hardly changes; in other words, only α-amylase immobilized on the particles is selectively activated due to heat generation from the particles.

  18. SolCalc: A Suite for the Calculation and the Display of Magnetic Fields Generated by Solenoid Systems

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, M. L. [Fermilab

    2014-07-01

    SolCalc is a software suite that computes and displays magnetic fields generated by a three dimensional (3D) solenoid system. Examples of such systems are the Mu2e magnet system and Helical Solenoids for muon cooling systems. SolCalc was originally coded in Matlab, and later upgraded to a compiled version (called MEX) to improve solving speed. Matlab was chosen because its graphical capabilities represent an attractive feature over other computer languages. Solenoid geometries can be created using any text editor or spread sheets and can be displayed dynamically in 3D. Fields are computed from any given list of coordinates. The field distribution on the surfaces of the coils can be displayed as well. SolCalc was benchmarked against a well-known commercial software for speed and accuracy and the results compared favorably.

  19. High performance wash-free magnetic bioassays through microfluidically enhanced particle specificity.

    Science.gov (United States)

    Bechstein, Daniel J B; Lee, Jung-Rok; Ooi, Chin Chun; Gani, Adi W; Kim, Kyunglok; Wilson, Robert J; Wang, Shan X

    2015-06-30

    Magnetic biosensors have emerged as a sensitive and versatile platform for high performance medical diagnostics. These magnetic biosensors require well-tailored magnetic particles as detection probes, which need to give rise to a large and specific biological signal while showing very low nonspecific binding. This is especially important in wash-free bioassay protocols, which do not require removal of particles before measurement, often a necessity in point of care diagnostics. Here we show that magnetic interactions between magnetic particles and magnetized sensors dramatically impact particle transport and magnetic adhesion to the sensor surfaces. We investigate the dynamics of magnetic particles' biomolecular binding and magnetic adhesion to the sensor surface using microfluidic experiments. We elucidate how flow forces can inhibit magnetic adhesion, greatly diminishing or even eliminating nonspecific signals in wash-free magnetic bioassays, and enhancing signal to noise ratios by several orders of magnitude. Our method is useful for selecting and optimizing magnetic particles for a wide range of magnetic sensor platforms.

  20. Electron microscopy observations of surface morphologies and particle arrangement behaviors of magnetic fluids

    Institute of Scientific and Technical Information of China (English)

    沈辉; 徐雪青; 王伟

    2003-01-01

    The surface morphology of quasi-periodic stripe-shaped patterns of magnetite fluids was observed in applied perpendicular magnetic fields by means of scanning electron microscopy. The nanoparticles of the magnetite fluids are arranged in oriental quasilinear chains in applied perpendicular magnetic fields as observed using transmission electron microscopy. This arrangement results from particle-particle interactions and particle-carrier liquids interactions, which are eventually controlled by the magnetic fields distribution.

  1. Formation of spectrum of accelerated particles and the hydromagnetic turbulence in the variable magnetic field

    CERN Document Server

    Savane, Y S; Faza-Barry, M; Lomonossov, V

    2002-01-01

    We study the acceleration of charged particles by the variable magnetic field. The study is based on the determination of spectrum of accelerated particles and the spectrum of hydro magnetic turbulence. We plan the self-consistent system of equation and we also find out the solution of the system for the spectrum of particles and hydro magnetic turbulence with the conditions of effective acceleration in the cosmic space of solar system.

  2. Microcapillary flow behavior of magnetic nanofluids in the presence of plate shaped bentonite particles

    Science.gov (United States)

    Parmar, Mayur; Virpura, Hiral; Patel, Rajesh

    2013-04-01

    Plate shaped bentonite particles of size ˜600 nm and thickness ˜2 nm are dispersed in a magnetic nanofluid. Magnetic field dependent flow behavior of this composite suspension is studied using a horizontal microcapillary placed between the poles of an electromagnet. The plate shaped bentonite particle produces extra hindrance to the flow under the application of moderate magnetic field and produces an enhanced magnetoviscous effect. 75% volume concentration of bentonite produces eight times larger change in magnetic field dependent viscosity than does the pure magnetic nanofluid. Hindrance to the flow is due to the chain like structure of magnetic nanoparticles, tumbling and rotational motion of bentonite particles and interaction between magnetic and bentonite particles. The field-induced structures are also observed using an optical microscope. Results offer several advantages over the inverse MR effect as well as to study the motion of biological cells and tissues under the effect of magnetic field.

  3. Understanding the focusing of charged particle for 2D sheet beam in a cusped magnetic field

    CERN Document Server

    Banerjee, Tusharika S; Reddy, K T V

    2016-01-01

    The requirement of axial magnetic field for focusing and transportation of sheet beam using cusped magnets is less as compared to solenoid magnetic fields which is uniform. There is often some confusion about how a cusped magnetic field focuses high current density sheet beam because it is generally understood that non-uniform magnetic field cannot guide the particle beam along its axis of propagation .In this paper, we perform simple analysis of the dynamics of sheet beam in a cusped magnetic field with single electron model and emphasize an intuitive understanding of interesting features (as beam geometry, positioning of permanent magnets, particle radius,particle velocity,radius of curvature of particle inside cusped magnetic field)

  4. Magnetic nanoparticles in different biological environments analyzed by magnetic particle spectroscopy

    Science.gov (United States)

    Löwa, Norbert; Seidel, Maria; Radon, Patricia; Wiekhorst, Frank

    2017-04-01

    Quantification of magnetic iron oxide nanoparticles (MNP) in biological systems like cells, tissue, or organs is of vital importance for development of novel biomedical applications, e.g. magnetofection, drug targeting or hyperthermia. Among others, the recently developed magnetic measurement technique magnetic particle spectroscopy (MPS) provides signals that are specific for MNP. MPS is based on the non-linear magnetic response of MNP exposed to a strong sinusoidal excitation field of up to 25 mT amplitude and 25 kHz frequency. So far, it has been proven a powerful tool for quantification of MNP in biological systems. In this study we investigated in detail the influence of typical biological media on the magnetic behavior of different MNP systems by MPS. The results reveal that amplitude and shape (ratio of harmonics) of the MPS spectra allow for perceptively monitoring changes in MNP magnetism caused by different physiological media. Additionally, the observed linear correlation between MPS amplitude and shape alterations can be used to reduce the quantification uncertainty for MNP suspended in a biological environment.

  5. Electric and magnetic dipolar response of small dielectric particles: Scattering anisotropy and optical forces

    Directory of Open Access Journals (Sweden)

    R. Gomez-Medina

    2011-09-01

    Full Text Available We predict that real small dielectric particles made of non-magnetic materials present non-conventional scattering properties similar to those previously reported for somewhat hypothetical magnetodielectric particles.

  6. Use of a magnetic fluid for particle size analysis by a sedimentation method

    Energy Technology Data Exchange (ETDEWEB)

    Dikansky, Yury [Department of Physics, Stavropol State University, 1 Pushkin Street, Stavropol 355009 (Russian Federation)], E-mail: dikansky@mail.ru; Zakinyan, Arthur; Bedganian, Marita [Department of Physics, Stavropol State University, 1 Pushkin Street, Stavropol 355009 (Russian Federation)

    2009-05-15

    A new method of particle size analysis of micrometer-sized particles is discussed. The improved method of sedimentation analysis with magnetic fluids has the potential and versatility to characterize polydisperse systems.

  7. The effect of cooling on particle trajectories and acceleration in relativistic magnetic reconnection

    CERN Document Server

    Kagan, Daniel; Piran, Tsvi

    2016-01-01

    The maximum synchrotron burnoff limit of 160 MeV represents a fundamental limit to radiation resulting from electromagnetic particle acceleration in one-zone ideal plasmas. In magnetic reconnection, however, particle acceleration and radiation are decoupled because the electric field is larger than the magnetic field in the diffusion region. We carry out two-dimensional particle-in-cell simulations to determine the extent to which magnetic reconnection can produce synchrotron radiation above the burnoff limit. We use the test particle comparison (TPC) method to isolate the effects of cooling by comparing the trajectories and acceleration efficiencies of test particles incident on such a reconnection region with and without cooling them. We find that the cooled and uncooled particle trajectories are typically similar during acceleration in the reconnection region, and derive an effective limit on particle acceleration that is inversely proportional to the average magnetic field experienced by the particle duri...

  8. Nondestructive Testing Magnetic Particle RQA/M1-5330.11.

    Science.gov (United States)

    National Aeronautics and Space Administration, Huntsville, AL. George C. Marshall Space Flight Center.

    As one in the series of programmed instruction handbooks, prepared by the U. S. space program, home study material is presented in this volume concerning familiarization and orientation on magnetic particle properties. The subject is presented under the following headings: Magnetism, Producing a Magnetic Field, Magnetizing Currents, Materials and…

  9. Allergens displayed on virus-like particles are highly immunogenic but fail to activate human mast cells.

    Science.gov (United States)

    Engeroff, P; Caviezel, F; Storni, F; Thoms, F; Vogel, M; Bachmann, M F

    2017-08-08

    The goal of allergen-specific immunotherapy is the induction of protective immune responses in the absence of anaphylactic reactions. We have previously shown that Fel d 1, the major cat allergen, displayed in a repetitive fashion on virus-like particles (VLPs) may fulfill these criteria. Specifically, Fel d 1 on VLPs induced strongly increased protective IgG responses compared to free allergen in mice while anaphylactic reactions were essentially abolished. Here we extend these findings to human mast cells and offer a mechanistic explanation for the reduced anaphylactic activity. We differentiated human mast cells in vitro from blood-derived stem cell progenitors and sensitized the cells with a monoclonal Fel d 1-specific IgE. We compared the capability of Fel d 1 to induce mast cell activation in its free form versus displayed on VLPs and we performed allergen binding studies by surface plasmon resonance as well as flow cytometry. We show that free Fel d 1 induces degranulation of IgE-sensitized mast cells whereas Fel d 1 displayed on VLPs fails to induce mast cell activation. We demonstrate that this inability to activate mast cells is based on a biophysical as well as a biochemical mechanism. Firstly, Fel d 1 on VLPs showed a strongly impaired ability to bind to surface-bound IgE. Secondly, despite residual binding, repetitively displayed allergen on VLPs failed to cause mast cell activation. These findings indicate that repetitively displaying allergens on VLPs increases their immunogenicity while reducing their potential to cause anaphylactic reactions by essentially eliminating IgE-mediated activation of mast cells. © 2017 EAACI and John Wiley and Sons A/S. Published by John Wiley and Sons Ltd.

  10. Necrosis of HepG2 cancer cells induced by the vibration of magnetic particles

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Biran [Laboratoire de Physique de la Matière Condensée (LPMC), CNRS UMR 7336, Université de Nice Sophia Antipolis, Parc Valrose, 06108 Nice (France); Institut de Chimie de Nice, UMR 7272, Université de Nice Sophia Antipolis, CNRS, 28 Avenue de Valrose, F-06100 Nice (France); Bienvenu, Céline [Institut de Chimie de Nice, UMR 7272, Université de Nice Sophia Antipolis, CNRS, 28 Avenue de Valrose, F-06100 Nice (France); Mendez-Garza, Juan; Lançon, Pascal; Madeira, Alexandra [Laboratoire de Physique de la Matière Condensée (LPMC), CNRS UMR 7336, Université de Nice Sophia Antipolis, Parc Valrose, 06108 Nice (France); Vierling, Pierre [Institut de Chimie de Nice, UMR 7272, Université de Nice Sophia Antipolis, CNRS, 28 Avenue de Valrose, F-06100 Nice (France); Di Giorgio, Christophe, E-mail: christophe.di-giorgio@unice.fr [Institut de Chimie de Nice, UMR 7272, Université de Nice Sophia Antipolis, CNRS, 28 Avenue de Valrose, F-06100 Nice (France); Bossis, Georges, E-mail: bossis@unice.fr [Laboratoire de Physique de la Matière Condensée (LPMC), CNRS UMR 7336, Université de Nice Sophia Antipolis, Parc Valrose, 06108 Nice (France)

    2013-10-15

    Experiments of magnetolysis, i.e., destruction of cells induced with magnetic particles (MPs) submitted to the application of a magnetic field, were conducted on HepG2 cancer cells. We herein demonstrate the usefulness of combining anisotropic MPs with an alternative magnetic field in magnetolysis. Thus, the application of an alternative magnetic field of low frequency (a few Hertz) in the presence of anisotropic, submicronic particles allowed the destruction of cancer cells “in vitro”. We also show that a constant magnetic field is far less efficient than an oscillating one. Moreover, we demonstrate that, at equal particle volume, it is much more efficient to utilize spindle shaped particles rather than spherical ones. In order to get deeper insight into the mechanism of magnetolysis experiments, we performed a study by AFM, which strongly supports that the magnetic field induces the formation of clusters of particles becoming then large enough todamage cell membranes. - Highlights: • Magnetic force was applied on cancer cells through magnetic particles. • The penetration depth was predicted, both for spherical and ellipsoidal particles. • Alternative force was shown to damage the cells contrary to static force. • The effect of indentation of magnetic particles was compared to the one of AFM tips. • The damage was attributed to the formation of clusters of particles.

  11. Magnetization Reversal Process of Single Crystal α-Fe Containing a Nonmagnetic Particle

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yi [Tsinghua Univ., Beijing (China); Tsinghua Univ., Shenzhen (China); Xu, Ben [Tsinghua Univ., Beijing (China); Hu, Shenyang Y. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Li, Yulan [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Li, Qiu-Lin [Tsinghua Univ., Beijing (China); Tsinghua Univ., Shenzhen (China); Liu, Wei [Tsinghua Univ., Beijing (China); Tsinghua Univ., Shenzhen (China)

    2015-09-25

    The magnetization reversal process and hysteresis loops in a single crystal α-iron with nonmagnetic particles are simulated in this work based on the Landau-Lifshitz–Gilbert equation. The evolutions of the magnetic domain morphology are studied, and our analyses show that the magnetization reversal process is affected by the interaction between the moving domain wall and the existing nonmagnetic particles. This interaction strongly depends on the size of the particles, and it is found that particles with a particular size contribute the most to magnetic hardening.

  12. Simulation of dynamic magnetic particle capture and accumulation around a ferromagnetic wire

    Science.gov (United States)

    Choomphon-anomakhun, Natthaphon; Ebner, Armin D.; Natenapit, Mayuree; Ritter, James A.

    2017-04-01

    A new approach for modeling high gradient magnetic separation (HGMS)-type systems during the time-dependent capture and accumulation of magnetic particles by a ferromagnetic wire was developed. This new approach assumes the fluid (slurry) viscosity, comprised of water and magnetic particles, is a function of the magnetic particle concentration in the fluid, with imposed maxima on both the particle concentration and fluid viscosity to avoid unrealistic limits. In 2-D, the unsteady-state Navier-Stokes equations for compressible fluid flow and the unsteady-state continuity equations applied separately to the water and magnetic particle phases in the slurry were solved simultaneously, along with the Laplace equations for the magnetic potential applied separately to the slurry and wire, to evaluate the velocities and concentrations around the wire in a narrow channel using COMSOL Multiphysics. The results from this model revealed very realistic magnetically attractive and repulsive zones forming in time around the wire. These collection zones formed their own impermeable viscous phase during accumulation that was also magnetic with its area and magnetism impacting locally both the fluid flow and magnetic fields around the wire. These collection zones increased with an increase in the applied magnetic field. For a given set of conditions, the capture ability peaked and then decreased to zero at infinite time during magnetic particle accumulation in the collection zones. Predictions of the collection efficiency from a steady-state, clean collector, trajectory model could not show this behavior; it also agreed only qualitatively with the dynamic model and then only at the early stages of collection and more so at a higher applied magnetic field. Also, the collection zones decreased in size when the accumulation regions included magnetic particle magnetization (realistic) compared to when they excluded it (unrealistic). Overall, this might be the first time a mathematical

  13. Chemical Synthesis of Highly Magnetic, Air-Stable Silica-Coated iron Particles

    Institute of Scientific and Technical Information of China (English)

    姜洪英; 钟伟; 汤怒江; 刘先松; 都有为

    2003-01-01

    Highly magnetic and air-stable silica-coated Fe particles have been prepared by a rapid and simple method. The specific magnetization of the sample can be as high as 201 Am2/kg even including silica, which is a non-magnetic material. The iron particle coated with silica is passivated and protected from oxidation. The influences of H2 reduction temperature on structure and magnetic properties are also studied.

  14. Particles deposition induced by the magnetic field in the coronary bypass graft model

    Energy Technology Data Exchange (ETDEWEB)

    Bernad, Sandor I., E-mail: sandor.bernad@upt.ro [Centre of Advanced Research in Engineering Sciences, Romanian Academy, Timisoara Branch, 300223 Timisoara (Romania); Totorean, Alin F. [Department of Mechanical Machines, Equipment and Transportation, Politehnica University of Timisoara, RO-300222 Timisoara (Romania); Vekas, Ladislau, E-mail: vekas.ladislau@gmail.com [Centre of Advanced Research in Engineering Sciences, Romanian Academy, Timisoara Branch, 300223 Timisoara (Romania)

    2016-03-01

    Bypass graft failures is a complex process starting with intimal hyperplasia development which involve many hemodynamic and biological factors. This work presents experimental results regarding the possibility to use magnetic drug delivery to prevent the development of the intimal hyperplasia using a simplified but intuitive model. The primary goal is to understand the magnetic particle deposition in the anastomosis region of the bypass graft taking into account the complex flow field created in this area which involves recirculation region, flow mixing and presence of particles with high residence time. The three-dimensional geometry model was used to simulate the motion and accumulation of the particles under the magnetic field influence in anastomotic region of the coronary bypass graft. The flow patterns are evaluated both numerically and experimentally and show a good correlation in term of flow parameters like vortex length and flow stagnation point positions. Particle depositions are strongly dependent on the magnet position and consequently of the magnetic field intensity and field gradient. Increased magnetic field controlled by the magnet position induces increased particle depositions in the bypass graft anastomosis. The result shows that particle depositions depend on the bypass graft angle, and the deposition shape and particle accumulation respectively, depend by the flow pattern in the anastomosis region. - Highlights: • Particularity of the particle targeting in the bypass graft anastomosis. • Hemodynamic characteristics influence about the particle deposition. • Particle accumulation induces changes of the flow field in the graft anastomosis. • Bypass graft geometries influence the particle deposition.

  15. Core-shell composite particles composed of biodegradable polymer particles and magnetic iron oxide nanoparticles for targeted drug delivery

    Science.gov (United States)

    Oka, Chiemi; Ushimaru, Kazunori; Horiishi, Nanao; Tsuge, Takeharu; Kitamoto, Yoshitaka

    2015-05-01

    Core-shell composite particles with biodegradability and superparamagnetic behavior were prepared using a Pickering emulsion for targeted drug delivery based on magnetic guidance. The composite particles were composed of a core of biodegradable polymer and a shell of assembled magnetic iron oxide nanoparticles. It was found that the dispersibility of the nanoparticles is crucial for controlling the core-shell structure. The addition of a small amount of dispersant into the nanoparticle's suspension could improve the dispersibility and led to the formation of composite particles with a thin magnetic shell covering a polymeric core. The composite particles were also fabricated with a model drug loaded into the core, which was released via hydrolysis of the core under strong alkaline conditions. Because the core can also be biodegraded by lipase, this result suggests that the slow release of the drug from the composite particles should occur inside the body.

  16. Simulating net particle production and chiral magnetic current in a CP-odd domain

    CERN Document Server

    Fukushima, Kenji

    2015-01-01

    We elucidate the numerical formulation to simulate net production of particles and anomalous currents with CP-breaking background fields which cause an imbalance of particles over anti-particles. For a concrete demonstration we numerically impose pulsed electric and magnetic fields to observe that the dynamical chiral magnetic current follows together with the net particle production. The produced particle density is quantitatively consistent with the axial anomaly, while the chiral magnetic current is suppressed by a delay before the the onset of the current generation.

  17. Sequences for real-time magnetic particle imaging

    Directory of Open Access Journals (Sweden)

    Weber Matthias

    2015-09-01

    Full Text Available Magnetic Particle Imaging (MPI is a new imaging modality with the potential to be a new medical tool for angiographic diagnostics. It is capable of visualizing the spatial distribution of super-paramagnetic nanoparticles in high temporal and spatial resolution. Furthermore, the new spatial encoding scheme of a field free line (FFL promises a ten-fold higher sensitivity. So far, all know imaging devices featuring this new technique feature slow data acquisition and thus, are far away from real-time imaging capability. An actual real-time approach requires a complex field generator and an application of currents with very precise amplitude and phase. Here, we present the first implementation and calibration of a dynamic FFL field sequence enabling the acquisition of 50 MPI images per second in a mouse sized scanner.

  18. Quantum-mechanical relaxation model for characterization of fine particles magnetic dynamics in an external magnetic field

    Science.gov (United States)

    Mischenko, I.; Chuev, M.

    2016-12-01

    Principal difference of magnetic nanoparticles from the bulk matter which cannot be ignored when constructing upon them combined metamaterials and modern devices is the essential influence on their behavior thermal fluctuations of the environment. These disturbances lead to specific distributions of the particles characteristics and to stochastic reorientations of their magnetic moments. On the basis of quantum-mechanical representation of the particle possessing intrinsic magnetic anisotropy and being placed onto the external magnetic field we developed general approach to describe equilibrium magnetization curves and relaxation Mössbauer spectra of magnetic nanoparticles for diagnostics of magnetic nanomaterials in the whole temperature or external field ranges. This approach has universal character and may be applied not only to the systems under thermal equilibrium, but may in principle describe macroscopic dynamical phenomena such as magnetization reversal.

  19. Rheology and orientational distributions of rodlike particles with magnetic moment normal to the particle axis for semi-dense dispersions (analysis by means of mean field approximation).

    Science.gov (United States)

    Satoh, Akira; Sakuda, Yasuhiro

    2007-04-15

    We have considered a semi-dense dispersion composed of ferromagnetic rodlike particles with a magnetic moment normal to the particle axis to investigate the rheological properties and particle orientational distribution in a simple shear flow as well as an external magnetic field. We have adopted the mean field approximation to take into account magnetic particle-particle interactions. The basic equation of the orientational distribution function has been derived from the balance of the torques and solved numerically. The results obtained here are summarized as follows. For a very strong magnetic field, the magnetic moment of the rodlike particle is strongly restricted in the field direction, so that the particle points to directions normal to the flow direction (and also to the magnetic field direction). This characteristic of the particle orientational distribution is also valid for the case of a strong particle-particle interaction, as in the strong magnetic field case. To the contrary, for a weak interaction among particles, the particle orientational distribution is governed by a shear flow as well as an applied magnetic field. When the magnetic particle-particle interaction is strong under circumstances of an applied magnetic field, the magnetic moment has a tendency to incline to the magnetic field direction more strongly. This leads to the characteristic that the viscosity decreases with decreasing the distance between particles, and this tendency becomes more significant for a stronger particle-particle interaction. These characteristics concerning the viscosity are quite different from those for a semi-dense dispersion composed of rodlike particles with a magnetic moment along the particle direction.

  20. Biodegradable and magnetic core-shell composite particle prepared by emulsion solvent diffusion method

    Science.gov (United States)

    Oka, Chiemi; Ushimaru, Kazunori; Horiishi, Nanao; Tsuge, Takeharu; Kitamoto, Yoshitaka

    2016-02-01

    The present paper describes optimization of preparation conditions of a core-shell composite particle, and its heat generation by alternating magnetic fields. The composite particles are prepared with a modified emulsion solvent diffusion method, which is combined with Pickering emulsion stabilized by magnetic nanoparticles. In this method, the magnetic nanoparticles act as an emulsifier, and its amount and size are crucial to morphology of the composite particles. The magnetic nanoparticles of 8-9 nm would be strongly adsorbed at a liquid-liquid interface rather than the larger nanoparticles. At the optimized concentration of the magnetic nanoparticle’s suspension for the preparation, small and uniform composite particles are obtained since the amount of the nanoparticles is enough to prevent coalescence of droplets during the formation of the composites. The heat generation by alternating magnetic fields emerged certainly. This result suggests the composite particles have a property as a heat-generating carrier for hyperthermia treatment.

  1. Preparation and characterization of temperature-responsive magnetic composite particles for multi-modal cancer therapy.

    Science.gov (United States)

    Yao, Aihua; Chen, Qi; Ai, Fanrong; Wang, Deping; Huang, Wenhai

    2011-10-01

    The temperature-responsive magnetic composite particles were synthesized by emulsion-free polymerization of N-isopropylacrylamide (NIPAAm) and acrylamide (Am) in the presence of oleic acid-modified Fe(3)O(4) nanoparticles. The magnetic properties and heat generation ability of the composite particles were characterized. Furthermore, temperature and alternating magnetic field (AMF) triggered drug release behaviors of vitamin B(12)-loaded composite particles were also examined. It was found that composite particles enabled drug release to be controlled through temperature changes in the neighborhood of lower critical solution temperature. Continuous application of AMF resulted in an accelerated release of the loaded drug. On the other hand, intermittent AMF application to the composite particles resulted in an "on-off", stepwise release pattern. Longer release duration and larger overall release could be achieved by intermittent application of AMF as compared to continuous magnetic field. Such composite particles may be used for magnetic drug targeting followed by simultaneous hyperthermia and drug release.

  2. Zero-velocity magnetophoretic method for the determination of particle magnetic susceptibility.

    Science.gov (United States)

    Watarai, Hitoshi; Duc, Hoang Trong Tien; Lan, Tran Thi Ngoc; Zhang, Tianyi; Tsukahara, Satoshi

    2014-01-01

    A simple zero-velocity method to determine the particle magnetic susceptibility by measuring the magnetophoretic velocity was proposed. The principle is that the magnetophoretic velocity of a particle in a liquid medium must be zero when the magnetic susceptibilities of the medium and the particle are equal, or the gravity force and the magnetophoretic force are balanced. By changing the medium magnetic susceptibility and measuring the magnetophoretic velocity of a particle, the particle magnetic susceptibility was determined from the medium magnetic susceptibility under the zero-velocity condition. The feasibility of the method was demonstrated for polystyrene particles using a Dy(III) solution in the horizontal migration mode and different organic solvents in the vertical migration mode.

  3. Orientational order and translational dynamics of magnetic particle assemblies in liquid crystals.

    Science.gov (United States)

    Peroukidis, Stavros D; Klapp, Sabine H L

    2016-08-10

    Implementing extensive molecular dynamics simulations we explore the organization of magnetic particle assemblies (clusters) in a uniaxial liquid crystalline matrix comprised of rodlike particles. The magnetic particles are modelled as soft dipolar spheres with diameter significantly smaller than the width of the rods. Depending on the dipolar strength coupling the magnetic particles arrange into head-to-tail configurations forming various types of clusters including rings (closed loops) and chains. In turn, the liquid crystalline matrix induces long range orientational ordering to these structures and promotes their diffusion along the director of the phase. Different translational dynamics are exhibited as the liquid crystalline matrix transforms either from isotropic to nematic or from nematic to smectic state. This is caused due to different collective motion of the magnetic particles into various clusters in the anisotropic environments. Our results offer a physical insight for understanding both the structure and dynamics of magnetic particle assemblies in liquid crystalline matrices.

  4. Few-particle quantum magnetism with ultracold atoms

    Energy Technology Data Exchange (ETDEWEB)

    Murmann, Simon

    2015-11-25

    This thesis reports on the deterministic preparation of magnetically ordered states in systems of few fermionic atoms. We follow the concept of quantum simulation and use {sup 6}Li atoms in two different hyperfine states to mimic the behavior of electrons in a solidstate system. In a first experiment, we simulate the two-site Hubbard model by using two atoms in an isolated double-well potential. We prepare the two-particle ground state of this model with a fidelity exceeding 90%. By introducing strong repulsive interactions, we are able to realize a pure spin model and describe the energy spectrum with a two-site Heisenberg Hamiltonian. In a second experiment, we realize Heisenberg spin chains of up to four atoms in a single strongly-elongated trapping potential. Here, the atoms self-align along the potential axis due to strong repulsive interactions. We introduce two novel measurement techniques to identify the state of the spin chains and thereby confirm that we can deterministically prepare antiferromagnetic ground-state systems. This constitutes the first observation of quantum magnetism with fermionic atoms that exceeds nearest-neighbor correlations. Both the double-well system and the spin chains can be seen as building blocks of larger ground-state spin systems. Their deterministic preparation therefore opens up a new bottom-up approach to the experimental realization of quantum many-body systems with ultracold atoms.

  5. The Isolation of DNA by Polycharged Magnetic Particles: An Analysis of the Interaction by Zeta Potential and Particle Size

    Directory of Open Access Journals (Sweden)

    Yazan Haddad

    2016-04-01

    Full Text Available Magnetic isolation of biological targets is in major demand in the biotechnology industry today. This study considers the interaction of four surface-modified magnetic micro- and nanoparticles with selected DNA fragments. Different surface modifications of nanomaghemite precursors were investigated: MAN37 (silica-coated, MAN127 (polyvinylpyrrolidone-coated, MAN158 (phosphate-coated, and MAN164 (tripolyphosphate-coated. All particles were positive polycharged agglomerated monodispersed systems. Mean particle sizes were 0.48, 2.97, 2.93, and 3.67 μm for MAN37, MAN127, MAN164, and MAN158, respectively. DNA fragments exhibited negative zeta potential of −0.22 mV under binding conditions (high ionic strength, low pH, and dehydration. A decrease in zeta potential of particles upon exposure to DNA was observed with exception of MAN158 particles. The measured particle size of MAN164 particles increased by nearly twofold upon exposure to DNA. Quantitative PCR isolation of DNA with a high retrieval rate was observed by magnetic particles MAN127 and MAN164. Interaction between polycharged magnetic particles and DNA is mediated by various binding mechanisms such as hydrophobic and electrostatic interactions. Future development of DNA isolation technology requires an understanding of the physical and biochemical conditions of this process.

  6. The Isolation of DNA by Polycharged Magnetic Particles: An Analysis of the Interaction by Zeta Potential and Particle Size.

    Science.gov (United States)

    Haddad, Yazan; Xhaxhiu, Kledi; Kopel, Pavel; Hynek, David; Zitka, Ondrej; Adam, Vojtech

    2016-04-20

    Magnetic isolation of biological targets is in major demand in the biotechnology industry today. This study considers the interaction of four surface-modified magnetic micro- and nanoparticles with selected DNA fragments. Different surface modifications of nanomaghemite precursors were investigated: MAN37 (silica-coated), MAN127 (polyvinylpyrrolidone-coated), MAN158 (phosphate-coated), and MAN164 (tripolyphosphate-coated). All particles were positive polycharged agglomerated monodispersed systems. Mean particle sizes were 0.48, 2.97, 2.93, and 3.67 μm for MAN37, MAN127, MAN164, and MAN158, respectively. DNA fragments exhibited negative zeta potential of -0.22 mV under binding conditions (high ionic strength, low pH, and dehydration). A decrease in zeta potential of particles upon exposure to DNA was observed with exception of MAN158 particles. The measured particle size of MAN164 particles increased by nearly twofold upon exposure to DNA. Quantitative PCR isolation of DNA with a high retrieval rate was observed by magnetic particles MAN127 and MAN164. Interaction between polycharged magnetic particles and DNA is mediated by various binding mechanisms such as hydrophobic and electrostatic interactions. Future development of DNA isolation technology requires an understanding of the physical and biochemical conditions of this process.

  7. Large scale manufacture of magnetic polymer particles using membranes and microfluidic devices

    Institute of Scientific and Technical Information of China (English)

    Qingchun; Yuan; Richard; A.; Williams

    2007-01-01

    Magnetic polymer particles have found applications in diverse areas such as biomedical treatments, diagnosis and separation technology. These applications require the particles to have controlled sizes and narrow size distributions to gain better control and reproducibility in use. This paper reviews recent developments in the preparation of magnetic polymer particles at nano- and micro-scales by encapsulating magnetic components with dissolved or in situ formed polymers. Particle manufacture using emulsification and embedment methods produces magnetic polymer particles at micro-scale dimensions. However, the production of particles in this range using conventional emulsification methods affords very limited control over particle sizes and polydispersity. We report on alternative routes using membrane and microfluidics emulsification techniques, which have a capability to produce monodisperse emulsions and polymer microspheres (with coefficients of variation of less than 10%) in the range from submicrometer to a few 100 μm. The performance of these manufacturing methods is assessed with a view to future applications.

  8. PREPARATION OF Fe3O4/PSt MAGNETIC PARTICLES IN THE PRESENCE OF MAGNETIC FLUID IN ETHANOL/WATER MIXTURE

    Institute of Scientific and Technical Information of China (English)

    Xiao-bin Ding; Zong-hua Sun; Guo-xiang Wan; Ying-yan Jiang

    1999-01-01

    Fe3O4/Polystyrene(PSt) magnetic particles with core/shell structure have been prepared in the presence of Fe3O4 magnetic fluid in ethanol/water medium by dispersion polymerization of styrene. A Fe3O4particle formation mechanism was proposed. According to this mechanism, the size of particle nuclei is determined by the extent of aggregation of Fe3O4/oligomer. Magnetic particles with diameter ranging from 5to 200μm were prepared under different reaction conditions. Some polymerization parameters such as the concentration of monomer, stabilizer, initiator, and ethanol which affect particle size and size distribution are discussed and their effect on particle formation are explained by the proposed mechanism.

  9. Thixotropic Phenomena in Water: Quantitative Indicators of Casimir-Magnetic Transformations from Vacuum Oscillations (Virtual Particles

    Directory of Open Access Journals (Sweden)

    Michael A. Persinger

    2015-09-01

    Full Text Available The ~1.5 × 10−20 J which is considered a universal quantity and is associated with the movement of protons in water also relates to the ratio of the magnetic moment of a proton divided by its unit charge, multiplied by viscosity and applied over the O-H distance. There is quantitative evidence that thixotropy, the “spontaneous” increased viscosity in water when undisturbed, originates from the transformation of virtual particles or vacuum oscillations to real states through conversion of Casimir-magnetic energies that involve the frequency of the neutral hydrogen line and the upper bound threshold value for intergalactic magnetic fields. The results indicate that ½ of a single electron orbit is real (particle and the other ½ is virtual (wave. The matter equivalent per s for virtual-to-real states for electrons in 1 mL of water with a neutral pH is consistent with the numbers of protons (H+ and the measured range of molecules in the coherent domains for both width and duration of growth and is similar to widths of intergalactic dust grains from which planets and stars may condense. The de Broglie momentum for the lower boundary of the width of coherent domains multiplied by the fine structure velocity of an electron is concurrent with the quantum when one proton is being removed from another and when the upper boundary of the rest mass of a photon is transformed by the product of velocities for putative “entanglement” and light. Theoretical and experimental results indicate that components of thixotropy, such as specific domains of intercalated water molecules, could display excess correlations over very large distances. Because the energies of the universal quantity and water converge it may be a special conduit for discrete transformations from virtual to real states.

  10. Technogenic Magnetic Particles in Alkaline Dusts from Power and Cement Plants

    OpenAIRE

    2012-01-01

    During this study, we investigated the mineralogical characterization of technogenic magnetic particles (TMPs) contained in alkaline industrial dust and fly ash emitted by coal burning power plants and cement plants. The reaction of tested dust samples varied between values of pH 8 and pH 12. Their magnetic properties were characterized by measurement of magnetic susceptibility (χ), frequency dependence of magnetic susceptibility (χfd), and temperature dependence of magnetic susceptibility. M...

  11. Sugar Beet Yield and Quality Characteristics as Affected by Magnetic Field and Silver Nano Particles

    Directory of Open Access Journals (Sweden)

    H Feizi

    2012-02-01

    Full Text Available In order to study the effects of magnetic field, silver nano particles and micronutrient fertilizers on sugar beet, an experiment was conducted at Razavi Research and Technology Institute, Mashhad, Iran. Experiment carried out with seven treatments based on randomized complete block design with three replications. Treatments included (T1 magnetic field and silver nano particles + Kemira fertilizer (T2 magnetic field and silver nano particles + Humax fertilizer (T3 magnetic field and silver nano particles (T4 Kemira fertilizer (T5 Librel fertilizer (T6 Humax fertilizer and (T7 control. The results showed that exposure of sugar beet with magnetic field and silver nano particles (T3 increased root yield about 43 percent more than control. Magnetic field and silver nano particles stimulated shoot yield twice more than control. Magnetic field + silver nano particles treatment showed the highest sugar yield (12.71 ton/ha but T4 and control treatments showed the lowest sugar yield. Experimental treatments had no significant effects on root quality except potassium content. It is expectable that magnetic field and silver nano particles could be suitable as an alternative for chemical fertilizers to reduce their application.

  12. Biosensor based on the measurements of clustering dynamics of magnetic particles using a double pass setup

    DEFF Research Database (Denmark)

    2014-01-01

    Disclosed herein is a biosensor for optical detection of Brownian relaxation dynamics of magnetic particles measured by light transmission. The magnetic particles can be functionalized with biological ligands for the detection of target analytes in a sample. The setup may be implemented in a disc...

  13. Evidence for the presence of biogenic magnetic particles in the nocturnal migratory brown planthopper, Nilaparvata lugens.

    Science.gov (United States)

    Pan, Weidong; Wan, Guijun; Xu, Jingjing; Li, Xiaoming; Liu, Yuxin; Qi, Liping; Chen, Fajun

    2016-01-05

    Biogenic magnetic particles have been detected in some migratory insects, which implies the basis of magnetoreception mechanism for orientation and navigation. Here, the biogenic magnetic particles in the migratory brown planthopper (BPH), Nilaparvata lugens were qualitatively measured by SQUID magnetometry, and their characteristics were further determined by Prussian Blue staining, electron microscopy and energy dispersive x-ray spectroscopy. The results indicate that there were remarkable magnetic materials in the abdomens and not in the head or thorax of the 3(rd)-5(th) instar nymphs, and in macropterous and brachypterous female and male adults of BPH. The size of magnetic particles was shown to be between 50-450 nm with a shape factor estimate of between 0.8-1.0 for all the tested BPHs. Moreover, the amount of magnetic particles was associated with the developmental stage (the 3(rd)-5(th) instar), wing form (macropterous vs. brachypterous) and sex. The macropterous female adults had the largest amount of magnetic particles. Although the existence of magnetic particles in the abdomens of BPH provides sound basis for the assumption of magnetic orientation, further behavioral studies and complementary physical characterization experiments should be conducted to determine whether the orientation behavior of BPH is associated with the magnetic particles detected in this study.

  14. Approximate Integrals of rf-driven Particle Motion in Magnetic Field

    Energy Technology Data Exchange (ETDEWEB)

    I.Y. Dodin; N.J. Fisch

    2004-04-26

    For a particle moving in nonuniform magnetic field under the action of an rf wave, ponderomotive effects result from rf-driven oscillations nonlinearly coupled with Larmor rotation. Using Lagrangian and Hamiltonian formalism, we show how, despite this coupling, two independent integrals of the particle motion are approximately conserved. Those are the magnetic moment of free Larmor rotation and the quasi-energy of the guiding center motion parallel to the magnetic field. Under the assumption of non-resonant interaction of the particle with the rf field, these integrals represent adiabatic invariants of the particle motion.

  15. Fermi~I particle acceleration in converging flows mediated by magnetic reconnection

    CERN Document Server

    Bosch-Ramon, V

    2012-01-01

    Converging flows with strong magnetic fields of different polarity can accelerate particles through magnetic reconnection. If the particle mean free path is larger than the thickness of the reconnection layer, but much smaller than the entire reconnection structure, the particle will mostly interact with the incoming flows potentially with a very low escape probability. We explore, in general and also in some specific scenarios, the possibility of particles being accelerated in a magnetic reconnection layer by interacting only with the incoming flows. We characterize converging flows undergoing magnetic reconnection, and derive analytical estimates for the particle energy distribution, acceleration rate, and maximum energies achievable in these flows. We also discuss a possible scenario, based on jets dominated by magnetic fields of changing polarity, in which this mechanism may operate. The proposed acceleration mechanism operates if the thickness of the reconnection layer is much smaller than its transversa...

  16. Magnetic properties in an ash flow tuff with continuous grain size variation: a natural reference for magnetic particle granulometry

    Science.gov (United States)

    Till, J.L.; Jackson, M.J.; Rosenbaum, J.G.; Solheid, P.

    2011-01-01

    The Tiva Canyon Tuff contains dispersed nanoscale Fe-Ti-oxide grains with a narrow magnetic grain size distribution, making it an ideal material in which to identify and study grain-size-sensitive magnetic behavior in rocks. A detailed magnetic characterization was performed on samples from the basal 5 m of the tuff. The magnetic materials in this basal section consist primarily of (low-impurity) magnetite in the form of elongated submicron grains exsolved from volcanic glass. Magnetic properties studied include bulk magnetic susceptibility, frequency-dependent and temperature-dependent magnetic susceptibility, anhysteretic remanence acquisition, and hysteresis properties. The combined data constitute a distinct magnetic signature at each stratigraphic level in the section corresponding to different grain size distributions. The inferred magnetic domain state changes progressively upward from superparamagnetic grains near the base to particles with pseudo-single-domain or metastable single-domain characteristics near the top of the sampled section. Direct observations of magnetic grain size confirm that distinct transitions in room temperature magnetic susceptibility and remanence probably denote the limits of stable single-domain behavior in the section. These results provide a unique example of grain-size-dependent magnetic properties in noninteracting particle assemblages over three decades of grain size, including close approximations of ideal Stoner-Wohlfarth assemblages, and may be considered a useful reference for future rock magnetic studies involving grain-size-sensitive properties.

  17. Prospects for searching axion-like particle dark matter with dipole, toroidal and wiggler magnets

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Oliver K. [Yale Univ., New Haven, CT (United States). Dept. of Physics; Betz, Michael; Caspers, Fritz [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Jaeckel, Joerg [Institute for Particle Physics Phenomenology, Durham (United Kingdom); Lindner, Axel; Ringwald, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Semertzidis, Yannis [Brookhaven National Lab., Upton, NY (United States); Sikivie, Pierre [Florida Univ., Gainesville, FL (United States). Dept. of Physics; Zioutas, Konstantin [Patras Univ. (Greece)

    2011-10-15

    In this work we consider searches for dark matter made of axions or axion-like particles (ALPs) using resonant radio frequency cavities inserted into dipole magnets from particle accelerators, wiggler magnets developed for accelerator based advanced light sources, and toroidal magnets similar to those used in particle physics detectors. We investigate the expected sensitivity of such ALP dark matter detectors and discuss the engineering aspects of building and tuning them. Brief mention is also made of even stronger field magnets that are becoming available due to improvements in magnetic technology. It is concluded that new experiments utilizing already existing magnets could greatly enlarge the mass region in searches for axion-like dark matter particles. (orig.)

  18. A Model for Predicting Magnetic Particle Capture in a Microfluidic Bioseparator

    CERN Document Server

    Furlani, E P; Ng, K C; Sahoo, Y; Wortman, J C

    2006-01-01

    A model is presented for predicting the capture of magnetic micro/nano-particles in a bioseparation microsystem. This bioseparator consists of an array of conductive elements embedded beneath a rectangular microfluidic channel. The magnetic particles are introduced into the microchannel in solution, and are attracted and held by the magnetic force produced by the energized elements. Analytical expressions are obtained for the dominant magnetic and fluidic forces on the particles as they move through the microchannel. These expressions are included in the equations of motion, which are solved numerically to predict particle trajectories and capture time. This model is well-suited for parametric analysis of particle capture taking into account variations in particle size, material properties, applied current, microchannel dimensions, fluid properties, and flow velocity.

  19. Magnetic particle motions within living cells. Measurement of cytoplasmic viscosity and motile activity.

    Science.gov (United States)

    Valberg, P A; Feldman, H A

    1987-01-01

    Submicrometer magnetic particles, ingested by cells and monitored via the magnetic fields they generate, provide an alternative to optical microscopy for probing movement and viscosity of living cytoplasm, and can be used for cells both in vitro and in vivo. We present methods for preparing lung macrophages tagged with magnetic particles for magnetometric study. Interpretation of the data involves fitting experimental remanent-field decay curves to nonlinear mechanistic models of intracellular particle motion. The model parameters are sensitive to mobility and apparent cytoplasmic viscosity experienced by particle-containing organelles. We present results of parameter estimation for intracellular particle behavior both within control cells and after (a) variable magnetization duration, (b) incubation with cytochalasin D, and (c) particle twisting by external fields. Magnetometric analysis showed cytoplasmic elasticity, dose-dependent motion inhibition by cytochalasin D, and a shear-thinning apparent viscosity. Images FIGURE 1 FIGURE 2 PMID:3676436

  20. Optimization of influencing factors of nucleic acid adsorption onto silica-coated magnetic particles: application to viral nucleic acid extraction from serum.

    Science.gov (United States)

    Sun, Ning; Deng, Congliang; Liu, Yi; Zhao, Xiaoli; Tang, Yan; Liu, Renxiao; Xia, Qiang; Yan, Wenlong; Ge, Guanglu

    2014-01-17

    We present a detailed study of nucleic acid adsorption onto silica-coated magnetic particles in the presence of guanidinium thiocyanate, and extraction of nucleic acid from two important transfusion-transmitted viruses using these particles. Silica-coated magnetic particles were prepared by encapsulating Fe3O4 nanoparticles with tetraethylorthosilicate (TEOS) hydrolysis. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS) and vibrating sample magnetometer (VSM) were used for particle characterization. The results indicate that silica-coated magnetic particles are spheroid with a narrow hydrodynamic size distribution of about 500nm. VSM data indicates that these particles display paramagnetic behavior with saturation magnetization of about 30emu/g. The adsorption capacities were evaluated with DNA from salmon sperm and RNA of Escherichia coli strain JM109 in the presence of guanidinium thiocyanate. The maximum of adsorption is up to 10.6mg DNA or 7.7mg RNA per 1g of silica-coated magnetic particles with 4M guanidinium thiocyanate (GTC) at pH 5.5 without adding ethanol. The influencing factors were analyzed in term of the adsorption of nucleic acids onto silica-coated magnetic particles. The adsorption capacity in acidic condition is found to be larger than that in alkaline condition and increases with adding equivalent volume of ethanol. A simple method was therefore established to extract nucleic acids of two important transfusion-transmitted viruses from serum and compared with the commercial kits. The results indicate that the extraction method based on silica-coated magnetic particles can be adapted to rapidly and facilely isolate viral nucleic acid for diagnosis of viral infection from serum within 30min, irrespective of genome compositions of virus.

  1. Comparison of Influenza Virus Particle Purification Using Magnetic Sulfated Cellulose Particles with an Established Centrifugation Method for Analytics.

    Science.gov (United States)

    Serve, Anja; Pieler, Michael Martin; Benndorf, Dirk; Rapp, Erdmann; Wolff, Michael Werner; Reichl, Udo

    2015-11-03

    A method for the purification of influenza virus particles using novel magnetic sulfated cellulose particles is presented and compared to an established centrifugation method for analytics. Therefore, purified influenza A virus particles from adherent and suspension MDCK host cell lines were characterized on the protein level with mass spectrometry to compare the viral and residual host cell proteins. Both methods allowed one to identify all 10 influenza A virus proteins, including low-abundance proteins like the matrix protein 2 and nonstructural protein 1, with a similar impurity level of host cell proteins. Compared to the centrifugation method, use of the novel magnetic sulfated cellulose particles reduced the influenza A virus particle purification time from 3.5 h to 30 min before mass spectrometry analysis.

  2. Thermal relaxation of interacting fine magnetic particles - field-cooled and zero-field-cooled magnetization variation

    Energy Technology Data Exchange (ETDEWEB)

    Jing Ju Lu; Hong Yuan Deng; Huei Li Huang E-mail: hlhuang@phys.ntu.edu.tw

    2000-02-01

    Dipole interaction makes average energy barrier of magnetic fine particles for thermal relaxation reduced while the corresponding blocking temperature distribution is a function of both dipolar interaction strength and particle size distribution of the system. Flatness and fast drop-off of the {lambda}-shape behavior of the field-cooled and zero-field-cooled magnetization varies with both dipolar intereaction strength and field level applied.

  3. Detecting molecules and cells labeled with magnetic particles using an atomic magnetometer

    Energy Technology Data Exchange (ETDEWEB)

    Yu Dindi; Ruangchaithaweesuk, Songtham; Yao Li; Xu Shoujun, E-mail: sxu7@uh.edu [University of Houston, Department of Chemistry (United States)

    2012-09-15

    The detection of magnetically labeled molecules and cells involves three essential parameters: sensitivity, spatial resolution, and molecular specificity. We report on the use of atomic magnetometry and its derivative techniques to achieve high performance in terms of all these parameters. With a sensitivity of 80 fT/{radical}Hz for dc magnetic fields, we show that 7,000 streptavidin-conjugated magnetic microparticles magnetized by a permanent magnet produce a magnetic field of 650 pT; this result predicts that a single such particle can be detected during one second of signal averaging. Spatial information is obtained using a scanning magnetic imaging scheme. The spatial resolution is 20 {mu}m with a detection distance of more than 1 cm; this distance is much longer than that in previous reports. The molecular specificity is achieved using force-induced remnant magnetization spectroscopy, which currently uses an atomic magnetometer for detection. As an example, we perform measurement of magnetically labeled human CD4+ T cells, whose count in the blood is the diagnostic criterion for human immunodeficiency virus infection. Magnetic particles that are specifically bound to the cells are resolved from nonspecifically bound particles and quantitatively correlate with the number of cells. The magnetic particles have an overall size of 2.8 {mu}m, with a magnetic core in nanometer regime. The combination of our techniques is predicted to be useful in molecular and cellular imaging.

  4. Influence of Particle Size on Magnetic Properties of Soils in Zhejiang Province, China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The relationship between magnetic properties and particle size of soils derived from metamorphic rock,basalt, granite, Quaternary red clay, limestone and mudstone from Zhejiang Province, East China was stu died. Based on the variations of the mass magnetic susceptibility (x), anhysteretic remanent magnetization (ARM), and saturation isothermal remanent magnetizatization (SIRM) with soil particle size, the relationship could be classified into three groups. For the soils derived from metamorphic rock and basalt, magnetic values were the highest in the gravel and coarse sand fractions and decreased with decreasing soil particle size. The soils derived from sedimentary rock had a bimodal distribution of magnetic values, with peaks in 1~0.5 and 0.005~0.000 5 mm fractions. The soil developed on granite was characterized by a peak of magnetic valuein 0.001~0.000 5 mm fractions. Frequency-dependent susceptibility (xfd) and ratios of magnetic parameters (ARM/x, SIRM/x and SIRM/ARM) of soil particle fractions showed that variations in ferrimagnetic grainsize paralleled those in particle size. xfd peaked in clay fraction and decreased with increasing particle size,irrespective of soil parent materials. The acquisition curves of IRM and demagnetization parameter of different soil particles indicated that there were different agnetic minerals assemblages in different particle fractions..

  5. Controlled capillary assembly of magnetic Janus particles at fluid-fluid interfaces.

    Science.gov (United States)

    Xie, Qingguang; Davies, Gary B; Harting, Jens

    2016-08-21

    Capillary interactions can be used to direct assembly of particles adsorbed at fluid-fluid interfaces. Precisely controlling the magnitude and direction of capillary interactions to assemble particles into favoured structures for materials science purposes is desirable but challenging. In this paper, we investigate capillary interactions between magnetic Janus particles adsorbed at fluid-fluid interfaces. We develop a pair-interaction model that predicts that these particles should arrange into a side-side configuration, and carry out simulations that confirm the predictions of our model. Finally, we investigate the monolayer structures that form when many magnetic Janus particles adsorb at the interface. We find that the particles arrange into long, straight chains exhibiting little curvature, in contrast with capillary interactions between ellipsoidal particles. We further find a regime in which highly ordered, lattice-like monolayer structures form, which can be tuned dynamically using an external magnetic field.

  6. Trajectory of Charged Particle in Combined Electric and Magnetic Fields Using Interactive Spreadsheets

    Science.gov (United States)

    Tambade, Popat S.

    2011-01-01

    The objective of this article is to graphically illustrate to the students the physical phenomenon of motion of charged particle under the action of simultaneous electric and magnetic fields by simulating particle motion on a computer. Differential equations of motions are solved analytically and path of particle in three-dimensional space are…

  7. Mixing of photons with massive spin-two particles in a magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Biggio, Carla [Universidad Autonoma de Madrid (Spain). Dept. de Fisica Teorica]|[Max-Planck-Institut fuer Physik, Muenchen (Germany)]|[Genova Univ. (Italy). Dipt. di Fisica; Masso, Eduard [Universitat Autonoma de Barcelona (Spain). Inst. di Fisica D' Altes Energies; Redondo, Javier [Universitat Autonoma de Barcelona (Spain). Inst. di Fisica D' Altes Energies]|[Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2008-12-15

    We study the mixing of photons with hypothetical massive spin-two particles in the presence of a magnetic field. Mixing phenomena have been studied in the case of axion-like particles and strictly massless spin-two particles (gravitons) but not in this case. We find several interesting differences between them. (orig.)

  8. Charged Particle Trajectories in Sweeper Magnet for LISA Commissioning Run

    Science.gov (United States)

    Barker, Alyson; Garrett, Sierra; Taylor, Nathaniel; Rogers, Warren F.; MoNA Collaboration

    2013-10-01

    The Large multi-Institutional Scintillator Array (LISA) located at NSCL, MSU, is used in conjunction with the Modular Neutron Array (MoNA) and the Sweeper Magnet for experiments investigating the properties of exotic neutron-rich nuclei near the neutron dripline. In the LISA commissioning experiment, designed to study neutron unstable 24O excited states, decay energy calculations require careful determination of charged fragment and neutron trajectories following breakup. Tracking of charged particles through the Sweeper Chamber is accomplished using two Cathode Readout Drift Chamber (CRDC) detectors separated by 1.8 m. During analysis of individual charged fragment passages through both CRDCs we recognized a majority of events had incomplete charge collection in the center pads. Without correction, standard peak location algorithms incorrectly determined the individual event centroids thereby reducing trajectory resolution. We developed a method and algorithm for correctly determining the centroids to restore trajectory resolution, critical for neutron breakup event reconstruction and decay energy determination. Work supported by NSF grant PHY-1101745.

  9. Magnetic pumping as a source of particle heating

    Science.gov (United States)

    Lichko, Emily; Egedal, Jan; Daughton, William; Kasper, Justin

    2016-10-01

    Magnetic pumping is a means of heating plasmas for both fusion and astrophysical applications. This study presents a generalized model, related to the compressional pumping model Fisk & Gloeckler applied to the solar wind (2006). Unlike previous models, this model includes diffusion of the anisotropic features which develop in velocity space, thereby allowing energy to be transferred to the particles directly from the turbulence. By using various orderings, the drift kinetic equation can be reduced to a more general form of Parker's equation with an anisotropic distribution function. Through expansions in both pitch angle and in space, it can be shown that this equation has power law solutions and results in an overall heating of the plasma. This form of heating is related to transit-time damping. Kinetic simulations were performed to test the theoretical model and explore regimes where spatial and velocity diffusion are of the same order of importance, regimes not easily available to analytical calculations. These simulations appear to confirm the pumping model in the appropriate limits.

  10. Influence of surface modification of SrFe12O19 particles with oleic acid on magnetic microsphere preparation

    Institute of Scientific and Technical Information of China (English)

    Sifang Kong; Peipei Zhang; Xiufang Wen; Pihui Pi; Jiang Cheng; Zhuoru Yang; Jing Hai

    2008-01-01

    Oleic acid was used as surface modification agent to improve the hydrophobicity of magnetic strontium hexaferrite particles. The structure and properties of treated magnetic particles were characterized by scanning electronic microscopy (SEM), Fourier transform infrared spectra (FTIR), powder X-ray diffraction (XRD) and magnetic property measurement system (MPMS). The results show that oleic acid is chemically enwrapped on the surface of SrFe12O19 particles. Magnetic particles modified by oleic acid are highly dispersible and strongly responsive to magnetism but with slight decrease in saturated magnetization. The affinity between magnetic particles and monomers is improved by surface modification, resulting in increased particle incorporation in magnetic polymeric microspheres. The surface modification mechanism of magnetic particles by oleic acid is addressed in this work.

  11. Heat Transfer Simulation for Optimization and Treatment Planning of Magnetic Hyperthermia Using Magnetic Particle Imaging

    CERN Document Server

    Banura, Natsuo; Nishimoto, Kohei; Murase, Kenya

    2016-01-01

    This study was undertaken to develop a system for heat transfer simulation for optimization and treatment planning of magnetic hyperthermia treatment (MHT) using magnetic particle imaging (MPI). First, we performed phantom experiments to obtain the regression equation between the MPI pixel value and the specific absorption rate (SAR) of magnetic nanoparticles (MNPs), from which the MPI pixel value was converted to the SAR value in the simulation. Second, we generated the geometries for use in the simulation by processing X-ray computed tomography (CT) and MPI images of tumor-bearing mice injected intratumorally with MNPs (Resovist). The geometries and MPI images were then imported into software based on a finite element method (COMSOL Multiphysics) to compute the time-dependent temperature distribution for 20 min after the start of MHT. There was an excellent correlation between the MPI pixel value and the SAR value (r = 0.956). There was good agreement between the time course of the temperature rise in the t...

  12. Temperature-Switchable Agglomeration of Magnetic Particles Designed for Continuous Separation Processes in Biotechnology.

    Science.gov (United States)

    Paulus, Anja S; Heinzler, Raphael; Ooi, Huey Wen; Franzreb, Matthias

    2015-07-01

    The purpose of this work was the synthesis and characterization of thermally switchable magnetic particles for use in biotechnological applications such as protein purification and enzymatic conversions. Reversible addition-fragmentation chain-transfer polymerization was employed to synthesize poly(N-isopropylacrylamide) brushes via a "graft-from" approach on the surface of magnetic microparticles. The resulting particles were characterized by infrared spectroscopy and thermogravimetric analysis and their temperature-dependent agglomeration behavior was assessed. The influence of several factors on particle agglomeration (pH, temperature, salt type, and particle concentration) was evaluated. The results showed that a low pH value (pH 3-4), a kosmotropic salt (ammonium sulfate), and a high particle concentration (4 g/L) resulted in improved agglomeration at elevated temperature (40 °C). Recycling of particles and reversibility of the temperature-switchable agglomeration were successfully demonstrated for ten heating-cooling cycles. Additionally, enhanced magnetic separation was observed for the modified particles. Ionic monomers were integrated into the polymer chain to create end-group functionalized particles as well as two- and three-block copolymer particles for protein binding. The adsorption of lactoferrin, bovine serum albumin, and lysozyme to these ion exchange particles was evaluated and showed a binding capacity of up to 135 mg/g. The dual-responsive particles combined magnetic and thermoresponsive properties for switchable agglomeration, easy separability, and efficient protein adsorption.

  13. High-gradient permanent magnet apparatus and its use in particle collection

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Mengdawn; Ludtka, Gerard Michael; Avens, Larry R.

    2016-07-12

    A high-gradient permanent magnet apparatus for capturing paramagnetic particles, the apparatus comprising: (i) at least two permanent magnets positioned with like poles facing each other; (ii) a ferromagnetic spacer separating the like poles; and (iii) a magnetizable porous filling material in close proximity to the at least two permanent magnets. Also described is a method for capturing paramagnetic particles in which a gas or liquid sample containing the paramagnetic particles is contacted with the high-gradient permanent magnet apparatus described above; wherein, during the contacting step, the gas or liquid sample contacts the magnetizable porous filling material of the high-gradient permanent magnet apparatus, and at least a portion of the paramagnetic particles in the gas or liquid sample is captured on the magnetizable porous filling material.

  14. Role of particle masses in the magnetic field generation driven by the parity violating interaction

    CERN Document Server

    Dvornikov, Maxim

    2016-01-01

    Recently the new model for the generation of strong large scale magnetic fields in neutron stars, driven by the parity violating interaction, was proposed. In this model, the magnetic field instability results from the modification of the chiral magnetic effect in presence of the electroweak interaction between ultrarelativistic electrons and nucleons. In the present work we study how a nonzero mass of charged particles, which are degenerate relativistic electrons and nonrelativistic protons, influences the generation of the magnetic field in frames of this approach. For this purpose we calculate the induced electric current of these charged particles, electroweakly interacting with background neutrons and an external magnetic field, exactly accounting for the particle mass. This current is calculated by two methods: using the exact solution of the Dirac equation for a charged particle in external fields and computing the polarization operator of a photon in matter composed of background neutrons. We show tha...

  15. Motion behavior of non-metallic particles under high frequency magnetic field

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhong-tao; GUO Qing-tao; YU Feng-yun; LI Jie; ZHANG Jian; LI Ting-ju

    2009-01-01

    Non-metallic particles, especially alumina, are the main inclusions in aluminum and its alloys. Numerical simulation and the corresponding experiments were carried out to study the motion behavior of alumina particles in commercial pure aluminum under high frequency magnetic field. At the meantime, multi-pipe experiment was also done to discuss the prospect of continuous elimination of non-metallic particles under high frequency magnetic field. It is shown that: 1) results of numerical simulation are in good agreement with the experimental results, which certificates the rationality of the simulation model; 2) when the intensity of high frequency magnetic field is 0.06 T, the 30 μm alumina particles in melt inner could migrate to the edge and be removed within 2 s; 3) multi-pipe elimination of alumina particles under high frequency magnetic field is also effective and has a good prospect in industrial application.

  16. Particles deposition induced by the magnetic field in the coronary bypass graft model

    Science.gov (United States)

    Bernad, Sandor I.; Totorean, Alin F.; Vekas, Ladislau

    2016-03-01

    Bypass graft failures is a complex process starting with intimal hyperplasia development which involve many hemodynamic and biological factors. This work presents experimental results regarding the possibility to use magnetic drug delivery to prevent the development of the intimal hyperplasia using a simplified but intuitive model. The primary goal is to understand the magnetic particle deposition in the anastomosis region of the bypass graft taking into account the complex flow field created in this area which involves recirculation region, flow mixing and presence of particles with high residence time. The three-dimensional geometry model was used to simulate the motion and accumulation of the particles under the magnetic field influence in anastomotic region of the coronary bypass graft. The flow patterns are evaluated both numerically and experimentally and show a good correlation in term of flow parameters like vortex length and flow stagnation point positions. Particle depositions are strongly dependent on the magnet position and consequently of the magnetic field intensity and field gradient. Increased magnetic field controlled by the magnet position induces increased particle depositions in the bypass graft anastomosis. The result shows that particle depositions depend on the bypass graft angle, and the deposition shape and particle accumulation respectively, depend by the flow pattern in the anastomosis region.

  17. Magnetic properties of tidal flat sediments of the Yangtze Estuary and its relationship with particle size

    Institute of Scientific and Technical Information of China (English)

    张卫国; 俞立中

    2003-01-01

    This paper considers the magnetic properties of tidal flat sediments of the Yangtze Estuary and its relationship with particle size. The results indicate that magnetite of multi-domain (MD)/pseudo-single domain (PSD) in size dominates the magnetic properties of the samples. In addition to detrital magnetite, spherical magnetic particles are found in the magnetically strongest sediments near Shidongkou sewage outlet, which are ascribed to the product of industrial pollution. Particle size plays a strong role on the magnetic properties of the sediments. Magnetic susceptibility (Χ) and saturation isothermal remanent magnetization (SIRM) are positively correlated with the proportion of the fraction of 8-16 μm. However, magnetic parameters indicating fine-grained ferrimagnetic minerals, e.g. Susceptibility of anhysteric remanent magnetization (ΧARM), are highly correlated with the fine fraction of <4 μm and even the fraction of <32 μm. The results indicate that, when Χ Is used as a proxy for pollutant content, it is necessary to consider the possible influence of particle size on it. Due to the significant relationship between ΧARM and the fine component proportion, ΧARM can be applied to the normalization of pollutant content for particle size effect.

  18. Core–shell composite particles composed of biodegradable polymer particles and magnetic iron oxide nanoparticles for targeted drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Oka, Chiemi; Ushimaru, Kazunori [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan); Horiishi, Nanao [Bengala Techno Laboratory, 9-5-1006, 1-1 Kodai, Miyamae-ku, Kawasaki 216-0007 (Japan); Tsuge, Takeharu [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan); Kitamoto, Yoshitaka, E-mail: kitamoto.y.aa@m.titech.ac.jp [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan)

    2015-05-01

    Core–shell composite particles with biodegradability and superparamagnetic behavior were prepared using a Pickering emulsion for targeted drug delivery based on magnetic guidance. The composite particles were composed of a core of biodegradable polymer and a shell of assembled magnetic iron oxide nanoparticles. It was found that the dispersibility of the nanoparticles is crucial for controlling the core–shell structure. The addition of a small amount of dispersant into the nanoparticle's suspension could improve the dispersibility and led to the formation of composite particles with a thin magnetic shell covering a polymeric core. The composite particles were also fabricated with a model drug loaded into the core, which was released via hydrolysis of the core under strong alkaline conditions. Because the core can also be biodegraded by lipase, this result suggests that the slow release of the drug from the composite particles should occur inside the body. - Highlights: • Core−shell composites with biodegradability and magnetism are prepared. • O/W emulsion stabilized by iron oxide nanoparticles is utilized for the preparation. • The nanoparticle's dispersibility is crucial for controlling the composite structure. • Composites loading a model drug are also prepared. • The model drug is released with decomposition of the composites.

  19. Magnetic relaxation and correlating effective magnetic moment with particle size distribution in maghemite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Pisane, K.L. [Department of Physics & Astronomy, West Virginia University, Morgantown, WV 26506 (United States); Despeaux, E.C. [Department of Pharmaceutical Sciences, West Virginia University, Morgantown, WV 26506 (United States); Seehra, M.S., E-mail: mseehra@wvu.edu [Department of Physics & Astronomy, West Virginia University, Morgantown, WV 26506 (United States)

    2015-06-15

    The role of particle size distribution inherently present in magnetic nanoparticles (NPs) is examined in considerable detail in relation to the measured magnetic properties of oleic acid-coated maghemite (γ-Fe{sub 2}O{sub 3}) NPs. Transmission electron microscopy (TEM) of the sol–gel synthesized γ-Fe{sub 2}O{sub 3} NPs showed a log-normal distribution of sizes with average diameter 〈D〉=7.04 nm and standard deviation σ=0.78 nm. Magnetization, M, vs. temperature (2–350 K) of the NPs was measured in an applied magnetic field H up to 90 kOe along with the temperature dependence of the ac susceptibilities, χ′ and χ″, at various frequencies, f{sub m}, from 10 Hz to 10 kHz. From the shift of the blocking temperature from T{sub B}=35 K at 10 Hz to T{sub B}=48 K at 10 kHz, the absence of any significant interparticle interaction is inferred and the relaxation frequency f{sub o}=2.6×10{sup 10} Hz and anisotropy constant K{sub a}=5.48×10{sup 5} erg/cm{sup 3} are determined. For TT{sub B}, the data of M vs. H up to 90 kOe at several temperatures are analyzed two different ways: (i) in terms of the modified Langevin function yielding an average magnetic moment per particle μ{sub p}=7300(500) μ{sub B}; and (ii) in terms of log-normal distribution of moments yielding 〈μ〉=6670 µ{sub B} at 150 K decreasing to 〈μ〉=6100 µ{sub B} at 300 K with standard deviations σ≃〈μ〉/2. It is argued that the above two approaches yield consistent and physically meaningful results as long as the width parameter, s, of the log-normal distribution is less than 0.83. - Highlights: • Magnetic properties of γ-Fe{sub 2}O{sub 3} nanoparticles, size=7.04(0.78)nm, are reported. • Attempt frequency f{sub o}=2.6×10{sup 10} Hz and no interparticle interactions are inferred. • M vs. H above T{sub B} analyzed using modified Langevin yields µ{sub p}≈7300 µ{sub B} per particle. • M vs. H above T

  20. Particle Size-Specific Magnetic Measurements as a Tool for Enhancing Our Understanding of the Bulk Magnetic Properties of Sediments

    Directory of Open Access Journals (Sweden)

    Robert G. Hatfield

    2014-10-01

    Full Text Available Bulk magnetic properties of soils and sediments are often sensitive proxies for environmental change but commonly require interpretation in terms of the different sources of magnetic minerals (or components that combine to generate them. Discrimination of different components in the bulk magnetic record is often attempted through endmember unmixing and/or high resolution measurements that can require intensive measurement plans, assume linear additivity, and sometimes have difficulty in discriminating a large number of sources. As an alternative, magnetic measurements can be made on isolated sediment fractions that constitute the bulk sample. When these types of measurements are taken, heterogeneity is frequently observed between the magnetic properties of different fractions, suggesting different magnetic components often associate with different physical grain sizes. Using a particle size-specific methodology, individual components can be isolated and studied and bulk magnetic properties can be linked to, and isolated from, sedimentological variations. Deconvolving sedimentary and magnetic variability in this way has strong potential for increased understanding of how magnetic fragments are carried in natural systems, how they vary with different source(s, and allows for a better assessment of the effect environmental variability has in driving bulk magnetic properties. However, despite these benefits, very few studies exploit the information they can provide. Here, I present an overview of the different sources of magnetic minerals, why they might associate with different sediment fractions, how bulk magnetic measurements have been used to understand the contribution of different components to the bulk magnetic record, and outline how particle size-specific magnetic measurements can assist in their better understanding. Advantages and disadvantages of this methodology, their role alongside bulk magnetic measurements, and potential future

  1. Test particle transport in perturbed magnetic fields in tokamaks

    NARCIS (Netherlands)

    de Rover, M.; Schilham, A.M.R.; Montvai, A.; Cardozo, N. J. L.

    1999-01-01

    Numerical calculations of magnetic field line trajectories in a tokamak are used to investigate the common hypotheses that (i) field lines in a chaotic field make a Gaussian random walk and (ii) that the poloidal component of the magnetic field is uniform in regions with a chaotic magnetic field. Bo

  2. Coated magnetic particles in electrochemical systems: Synthesis, modified electrodes, alkaline batteries, and paste electrodes

    Science.gov (United States)

    Unlu, Murat

    Magnetic field effects on electrochemical reactions have been studied and shown to influence kinetics and dynamics. Recently, our group has introduced a novel method to establish magnetic field effects by incorporating inert, magnetic microparticles onto the electrode structure. This modification improved several electrochemical systems including modified electrodes, alkaline batteries, and fuel cells. This dissertation describes the applicability of magnetic microparticles and the understanding of magnetic field effects in modified electrodes, alkaline batteries, and paste electrodes. Magnetic effects are studied on electrodes that are coated with an ion exchange polymer that embeds chemically inert, commercial, magnetic microparticles. The flux (electrolysis current) of redox probe to the magnetically modified system is compared to a similar non-magnetic electrode. Flux enhancements of 60% are achieved at magnetically modified electrode as compared to non-magnetic controls. In addition to modifying electrode surfaces, the incorporation of magnetic microparticles into the electrode material itself establishes a 20% increase in flux. Possible magnetic field effects are evaluated. Study of samarium cobalt modified electrolytic manganese dioxide, EMD electrodes further establish a magnetic effect on alkaline cathode performance. Magnetic modification improves alkaline battery performance in primary and secondary applications. The reaction mechanism is examined through voltammetric methods. This work also includes coating protocols to produce inert magnetic microparticles with high magnetic content. Magnetite powders are encapsulated in a polymer matrix by dispersion polymerization. Composite particles are examined in proton exchange membrane fuel cells to study carbon monoxide tolerance.

  3. On-chip free-flow magnetophoresis: Separation and detection of mixtures of magnetic particles in continuous flow

    NARCIS (Netherlands)

    Pamme, Nicole; Eijkel, Jan C.T.; Manz, Andreas

    2006-01-01

    The complete separation of mixtures of magnetic particles was achieved by on-chip free-flow magnetophoresis. In continuous flow, magnetic particles were deflected from the direction of larninar flow by a perpendicular magnetic field depending on their magnetic susceptibility and size and on the flow

  4. Visualized effect of oxidation on magnetic recording fidelity in pseudo-single-domain magnetite particles

    DEFF Research Database (Denmark)

    Almeida, Trevor P.; Kasama, Takeshi; Muxworthy, Adrian R.

    2014-01-01

    fidelity of Fe3O4 particles is greatly diminished over time by progressive oxidation to less magnetic iron oxides, such as maghemite (γ-Fe2O3), with consequent alteration of remanent magnetization potentially having important geological significance. Here we use the complementary techniques...... of environmental transmission electron microscopy and off-axis electron holography to induce and visualize the effects of oxidation on the magnetization of individual nanoscale Fe3O4 particles as they transform towards γ-Fe2O3. Magnetic induction maps demonstrate a change in both strength and direction of remanent...

  5. Modeling and Characterization of Charged Particle Trajectories in an Oscillating Magnetic Field

    CERN Document Server

    Irawan, Dani; Khotimah, Siti Nurul; Latief, Fourier Dzar Eljabbar; Novitrian,

    2015-01-01

    A constant magnetic field has frequently been discussed and has been known that it can cause a charged particle to form interesting trajectories such as cycloid and helix in presence of electric field, but a changing magnetic field is rarely discussed. In this work, modeling and characterization of charged particle trajectories in oscillating magnetic field is reported. The modeling is performed using Euler method with speed corrector. The result shows that there are two types of trajectory patterns that will recur for every $180 n T_0$ ($n = 0, 1, 2, ..$) in increasing of magnetic field oscillation period, where $T_0$ is about $6.25\\times10^{-7}$ s.

  6. A Novel Virus-Like Particle Based Vaccine Platform Displaying the Placental Malaria Antigen VAR2CSA.

    Directory of Open Access Journals (Sweden)

    Susan Thrane

    Full Text Available Placental malaria caused by Plasmodium falciparum is a major cause of mortality and severe morbidity. Clinical testing of a soluble protein-based vaccine containing the parasite ligand, VAR2CSA, has been initiated. VAR2CSA binds to the human receptor chondroitin sulphate A (CSA and is responsible for sequestration of Plasmodium falciparum infected erythrocytes in the placenta. It is imperative that a vaccine against malaria in pregnancy, if administered to women before they become pregnant, can induce a strong and long lasting immune response. While most soluble protein-based vaccines have failed during clinical testing, virus-like particle (VLP based vaccines (e.g., the licensed human papillomavirus vaccines have demonstrated high efficacy, suggesting that the spatial assembly of the vaccine antigen is a critical parameter for inducing an optimal long-lasting protective immune response. We have developed a VLP vaccine display platform by identifying regions of the HPV16 L1 coat protein where a biotin acceptor site (AviTagTM can be inserted without compromising VLP-assembly. Subsequent biotinylation of Avi-L1 VLPs allow us to anchor monovalent streptavidin (mSA-fused proteins to the biotin, thereby obtaining a dense and repetitive VLP-display of the vaccine antigen. The mSA-VAR2CSA antigen was delivered on the Avi-L1 VLP platform and tested in C57BL/6 mice in comparison to two soluble protein-based vaccines consisting of naked VAR2CSA and mSA-VAR2CSA. The mSA-VAR2CSA Avi-L1 VLP and soluble mSA-VAR2CSA vaccines induced higher antibody titers than the soluble naked VAR2CSA vaccine after three immunizations. The VAR2CSA Avi-L1 VLP vaccine induced statistically significantly higher endpoint titres compared to the soluble mSA-VAR2CSA vaccine, after 1st and 2nd immunization; however, this difference was not statistically significant after 3rd immunization. Importantly, the VLP-VAR2CSA induced antibodies were functional in inhibiting the binding of

  7. Particle Acceleration, Magnetic Field Generation and Emission from Relativistic Jets and Supernova Remnants

    Science.gov (United States)

    Nishikawa, K.-I.; Hartmann, D. H.; Hardee, P.; Hededal, C.; Mizunno, Y.; Fishman, G. J.

    2006-01-01

    We performed numerical simulations of particle acceleration, magnetic field generation, and emission from shocks in order to understand the observed emission from relativistic jets and supernova remnants. The investigation involves the study of collisionless shocks, where the Weibel instability is responsible for particle acceleration as well as magnetic field generation. A 3-D relativistic particle-in-cell (RPIC) code has been used to investigate the shock processes in electron-positron plasmas. The evolution of theWeibe1 instability and its associated magnetic field generation and particle acceleration are studied with two different jet velocities (0 = 2,5 - slow, fast) corresponding to either outflows in supernova remnants or relativistic jets, such as those found in AGNs and microquasars. Slow jets have intrinsically different structures in both the generated magnetic fields and the accelerated particle spectrum. In particular, the jet head has a very weak magnetic field and the ambient electrons are strongly accelerated and dragged by the jet particles. The simulation results exhibit jitter radiation from inhomogeneous magnetic fields, generated by the Weibel instability, which has different spectral properties than standard synchrotron emission in a homogeneous magnetic field.

  8. Observational evidence for local particle acceleration associated with magnetically confined magnetic islands in the heliosphere - a review

    Science.gov (United States)

    Khabarova, O. V.; Zank, G. P.; Malandraki, O. E.; Li, G.; le Roux, J. A.; Webb, G. M.

    2017-01-01

    The occurrence of unusual energetic particle enhancements up to several MeV/nuc at leading edges of corotating interaction regions (CIRs), near the heliospheric current sheet and downstream of interplanetary shocks at 1AU has puzzled observers for a long time. Commonly accepted mechanisms of particle energization, such as a classical diffusive shock acceleration mechanism or magnetic reconnection at current sheets, are unable to explain these phenomena. We present a review of recently obtained observational results that attribute these atypical energetic particle events to local acceleration of particles in regions filled with small-scale magnetic islands confined by currents sheets of various origins. The observations are in very good accordance with the theory of stochastic particle energization in the supersonic solar wind via a sea of small-scale flux-ropes interacting dynamically (Zank et al., 2014, 2015; le Roux et al., 2015, 2016).

  9. Particle capture efficiency in a multi-wire model for high gradient magnetic separation

    KAUST Repository

    Eisenträger, Almut

    2014-07-21

    High gradient magnetic separation (HGMS) is an efficient way to remove magnetic and paramagnetic particles, such as heavy metals, from waste water. As the suspension flows through a magnetized filter mesh, high magnetic gradients around the wires attract and capture the particles removing them from the fluid. We model such a system by considering the motion of a paramagnetic tracer particle through a periodic array of magnetized cylinders. We show that there is a critical Mason number (ratio of viscous to magnetic forces) below which the particle is captured irrespective of its initial position in the array. Above this threshold, particle capture is only partially successful and depends on the particle\\'s entry position. We determine the relationship between the critical Mason number and the system geometry using numerical and asymptotic calculations. If a capture efficiency below 100% is sufficient, our results demonstrate how operating the HGMS system above the critical Mason number but with multiple separation cycles may increase efficiency. © 2014 AIP Publishing LLC.

  10. High-throughput top-down fabrication of uniform magnetic particles.

    Directory of Open Access Journals (Sweden)

    Julia Litvinov

    Full Text Available Ion Beam Aperture Array Lithography was applied to top-down fabrication of large dense (10(8-10(9 particles/cm(2 arrays of uniform micron-scale particles at rates hundreds of times faster than electron beam lithography. In this process, a large array of helium ion beamlets is formed when a stencil mask containing an array of circular openings is illuminated by a broad beam of energetic (5-8 keV ions, and is used to write arrays of specific repetitive patterns. A commercial 5-micrometer metal mesh was used as a stencil mask; the mesh size was adjusted by shrinking the stencil openings using conformal sputter-deposition of copper. Thermal evaporation from multiple sources was utilized to form magnetic particles of varied size and thickness, including alternating layers of gold and permalloy. Evaporation of permalloy layers in the presence of a magnetic field allowed creation of particles with uniform magnetic properties and pre-determined magnetization direction. The magnetic properties of the resulting particles were characterized by Vibrating Sample Magnetometry. Since the orientation of the particles on the substrate before release into suspension is known, the orientation-dependent magnetic properties of the particles could be determined.

  11. Theoretical predictions for spatially-focused heating of magnetic nanoparticles guided by magnetic particle imaging field gradients

    Energy Technology Data Exchange (ETDEWEB)

    Dhavalikar, Rohan [Department of Chemical Engineering, University of Florida, 1030 Center Drive, Gainesville, FL 32611 (United States); Rinaldi, Carlos, E-mail: carlos.rinaldi@bme.ufl.edu [Department of Chemical Engineering, University of Florida, 1030 Center Drive, Gainesville, FL 32611 (United States); J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, 1275 Center Drive, Gainesville, FL 32611 (United States)

    2016-12-01

    Magnetic nanoparticles in alternating magnetic fields (AMFs) transfer some of the field's energy to their surroundings in the form of heat, a property that has attracted significant attention for use in cancer treatment through hyperthermia and in developing magnetic drug carriers that can be actuated to release their cargo externally using magnetic fields. To date, most work in this field has focused on the use of AMFs that actuate heat release by nanoparticles over large regions, without the ability to select specific nanoparticle-loaded regions for heating while leaving other nanoparticle-loaded regions unaffected. In parallel, magnetic particle imaging (MPI) has emerged as a promising approach to image the distribution of magnetic nanoparticle tracers in vivo, with sub-millimeter spatial resolution. The underlying principle in MPI is the application of a selection magnetic field gradient, which defines a small region of low bias field, superimposed with an AMF (of lower frequency and amplitude than those normally used to actuate heating by the nanoparticles) to obtain a signal which is proportional to the concentration of particles in the region of low bias field. Here we extend previous models for estimating the energy dissipation rates of magnetic nanoparticles in uniform AMFs to provide theoretical predictions of how the selection magnetic field gradient used in MPI can be used to selectively actuate heating by magnetic nanoparticles in the low bias field region of the selection magnetic field gradient. Theoretical predictions are given for the spatial decay in energy dissipation rate under magnetic field gradients representative of those that can be achieved with current MPI technology. These results underscore the potential of combining MPI and higher amplitude/frequency actuation AMFs to achieve selective magnetic fluid hyperthermia (MFH) guided by MPI. - Highlights: • SAR predictions based on a field-dependent magnetization relaxation model.

  12. [Effects of the size of magnetic particles of immobilized enzyme reactors on the digestion performance].

    Science.gov (United States)

    Zhang, Jiao; Zhou, Lianqi; Tian, Fang; Zhang, Yangjun; Qian, Xiaohong

    2013-02-01

    We applied immobilized enzyme reactors prepared with different sizes of magnetic particles into protein and proteome digestion. In addition, the influences of different sizes of the magnetic particles were studied on the reunion, enzyme efficiency and leakage sites. The experimental results showed that in comparison with the submicron magnetic particles, the amount of trypsin immobilized on the magnetic nanoparticles was 3. 5 times more than that of the submicron magnetic particles. However, the enzymatic efficiency was at the same level when the same amount of trypsin was used, and the reunion phenomenon was obviously improved when the size of the magnetic nanoparticles increased. Taking the immobilized enzyme reactor of 20 nm magnetic nanoparticles as an example, the digestion performance was further examined. The experimental results showed that rapid digestion could be achieved within 1 mm when the mass ratio of the trypsin and bovine serum albumin was 1:1. The peptide number of 0 missed cleavage site and the sequence coverage changed little after the protein was digested for 10 mm. It was concluded that the digestion efficiency of the immobilized enzyme reactor was much better than that of the in-solution digestion. When the immobilized enzyme reactors and the free trypsin were used for digestion, little differences of the leakage sites were found. Therefore, the immobilized enzyme reactors prepared with different sizes of magnetic particles can be applied in proteomic research for quick and efficient digestion.

  13. Particle energisation in a collapsing magnetic trap model: the relativistic regime

    CERN Document Server

    Oskoui, Solmaz Eradat

    2014-01-01

    In solar flares, a large number of charged particles is accelerated to high energies. By which physical processes this is achieved is one of the main open problems in solar physics. It has been suggested that during a flare, regions of the rapidly relaxing magnetic field can form a collapsing magnetic trap (CMT) and that this trap may contribute to particle energisation.} In this Research Note we focus on a particular analytical CMT model based on kinematic magnetohydrodynamics. Previous investigations of particle acceleration for this CMT model focused on the non-relativistic energy regime. It is the specific aim of this Research Note to extend the previous work to relativistic particle energies. Particle orbits were calculated numerically using the relativistic guiding centre equations. We also calculated particle orbits using the non-relativistic guiding centre equations for comparison. For mildly relativistic energies the relativistic and non-relativistic particle orbits mainly agree well, but clear devia...

  14. Addressing of LnCaP Cell Using Magnetic Particles Assisted Impedimetric Microelectrode.

    Science.gov (United States)

    Nguyen, Dung Thi Xuan; Tran, Trong Binh; Nguyen, Phuong-Diem; Min, Junhong

    2016-03-01

    In this study, we provide a facile, effective technique for a simple isolation and enrichment of low metastatic prostate tumor cell LNCaP using biocompatible, magnetic particles asissted impedimetric sensing system. Hydrophobic cell membrane anchors (BAM) were generated onto magnetic particles which diameters vary from 50 nm to 5 μm and were used to capture LNCaP cells from the suspension. Finally, magnetic particle-LNCaP complex were addressed onto the surface of the interdigitated microelectrode (IDM). Cell viability was monitored by our laboratory developed-technique Electrical Cell Substrate Impedance Sensing (ECIS). The results reavealed that 50 nm-magnetic particles showed best performance in terms of cell separation and cell viability. This technique provides a simple and efficient method for the direct addressing of LNCaP cell on the surface and enhances better understanding of cell behavior for cancer management in the near future.

  15. Application of Gelatin-Coated Magnetic Particles for Isolation of Genomic DNA from Bones.

    Science.gov (United States)

    Khanpetch, Pongsak; Intorasoot, Sorasak; Prasitwattanseree, Sukon; Mekjaidee, Karnda; Mahakkanukrauh, Pasuk

    2015-07-01

    To develop a method for human genomic DNA extraction from bone using gelatin-coated magnetic particles. Thirty human metacarpal with the bone age ranging from 36 to 93 years were included in the present study. Genomic DNA was extracted from bones using gelatin-coated magnetic particles. The concentration and purity of DNA were analyzed in comparison with a reference method. In addition, the quality of extracted DNA was examined for sex determination by conventional polymerase chain reaction (PCR). The average DNA concentration using gelatin coated magnetic particles exhibited approximately 15 times higher than a reference method with an insignificantly difference of the DNA purity in both methods. Twelve (40%) and fifteen (50%) samples out of thirty DNA isolated using established and reference method, respectively, could be amplified and sex correctly determined by PCR. Gelatin coated magnetic particle is rapid, simple, and well-suited for isolation of DNA from bones.

  16. Use of mucolytics to enhance magnetic particle retention at a model airway surface

    Energy Technology Data Exchange (ETDEWEB)

    Ally, Javed [Department of Mechanical Engineering, University of Alberta, Edmonton, Alta., T6G 2G8 (Canada); Roa, Wilson [Department of Oncology, University of Alberta, Edmonton, Alta., T6G 1Z2 (Canada); Amirfazli, A. [Department of Mechanical Engineering, University of Alberta, Edmonton, Alta., T6G 2G8 (Canada)], E-mail: a.amirfazli@ualberta.ca

    2008-06-15

    A previous study has shown that retention of magnetic particles at a model airway surface requires prohibitively strong magnetic fields. As mucus viscoelasticity is the most significant factor contributing to clearance of magnetic particles from the airway surface, mucolytics are considered in this study to reduce mucus viscoelasticity and enable particle retention with moderate strength magnetic fields. The excised frog palate model was used to simulate the airway surface. Two mucolytics, N-acetylcysteine (NAC) and dextran sulfate (DS) were tested. NAC was found to enable retention at moderate field values (148 mT with a gradient of 10.2 T/m), whereas DS was found to be effective only for sufficiently large particle concentrations at the airway surface. The possible mechanisms for the observed behavior with different mucolytics are also discussed based on aggregate formation and the loading of cilia.

  17. Use of mucolytics to enhance magnetic particle retention at a model airway surface

    Science.gov (United States)

    Ally, Javed; Roa, Wilson; Amirfazli, A.

    A previous study has shown that retention of magnetic particles at a model airway surface requires prohibitively strong magnetic fields. As mucus viscoelasticity is the most significant factor contributing to clearance of magnetic particles from the airway surface, mucolytics are considered in this study to reduce mucus viscoelasticity and enable particle retention with moderate strength magnetic fields. The excised frog palate model was used to simulate the airway surface. Two mucolytics, N-acetylcysteine (NAC) and dextran sulfate (DS) were tested. NAC was found to enable retention at moderate field values (148 mT with a gradient of 10.2 T/m), whereas DS was found to be effective only for sufficiently large particle concentrations at the airway surface. The possible mechanisms for the observed behavior with different mucolytics are also discussed based on aggregate formation and the loading of cilia.

  18. Stimulated Brillouin scattering of an electromagnetic wave in weakly magnetized plasma with variably charged dust particles

    Indian Academy of Sciences (India)

    Sourabh Bal; M Bose

    2009-10-01

    We have investigated analytically the stimulated Brillouin scattering (SBS) of an electromagnetic wave in non-dissipative weakly magnetized plasma in the presence of dust particles with variable charge.

  19. Magnetically assisted chemical separation (MACS) process: Preparation and optimization of particles for removal of transuranic elements

    Energy Technology Data Exchange (ETDEWEB)

    Nunez, L.; Kaminski, M.; Bradley, C.; Buchholz, B.A.; Aase, S.B.; Tuazon, H.E.; Vandegrift, G.F. [Argonne National Lab., IL (United States); Landsberger, S. [Univ. of Illinois, Urbana, IL (United States)

    1995-05-01

    The Magnetically Assisted Chemical Separation (MACS) process combines the selectivity afforded by solvent extractants with magnetic separation by using specially coated magnetic particles to provide a more efficient chemical separation of transuranic (TRU) elements, other radionuclides, and heavy metals from waste streams. Development of the MACS process uses chemical and physical techniques to elucidate the properties of particle coatings and the extent of radiolytic and chemical damage to the particles, and to optimize the stages of loading, extraction, and particle regeneration. This report describes the development of a separation process for TRU elements from various high-level waste streams. Polymer-coated ferromagnetic particles with an adsorbed layer of octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) diluted with tributyl phosphate (TBP) were evaluated for use in the separation and recovery of americium and plutonium from nuclear waste solutions. Due to their chemical nature, these extractants selectively complex americium and plutonium contaminants onto the particles, which can then be recovered from the solution by using a magnet. The partition coefficients were larger than those expected based on liquid[liquid extractions, and the extraction proceeded with rapid kinetics. Extractants were stripped from the particles with alcohols and 400-fold volume reductions were achieved. Particles were more sensitive to acid hydrolysis than to radiolysis. Overall, the optimization of a suitable NMCS particle for TRU separation was achieved under simulant conditions, and a MACS unit is currently being designed for an in-lab demonstration.

  20. Lassa virus-like particles displaying all major immunological determinants as a vaccine candidate for Lassa hemorrhagic fever

    Directory of Open Access Journals (Sweden)

    Cashman Kathleen A

    2010-10-01

    Full Text Available Abstract Background Lassa fever is a neglected tropical disease with significant impact on the health care system, society, and economy of Western and Central African nations where it is endemic. Treatment of acute Lassa fever infections has successfully utilized intravenous administration of ribavirin, a nucleotide analogue drug, but this is not an approved use; efficacy of oral administration has not been demonstrated. To date, several potential new vaccine platforms have been explored, but none have progressed toward clinical trials and commercialization. Therefore, the development of a robust vaccine platform that could be generated in sufficient quantities and at a low cost per dose could herald a subcontinent-wide vaccination program. This would move Lassa endemic areas toward the control and reduction of major outbreaks and endemic infections. To this end, we have employed efficient mammalian expression systems to generate a Lassa virus (LASV-like particle (VLP-based modular vaccine platform. Results A mammalian expression system that generated large quantities of LASV VLP in human cells at small scale settings was developed. These VLP contained the major immunological determinants of the virus: glycoprotein complex, nucleoprotein, and Z matrix protein, with known post-translational modifications. The viral proteins packaged into LASV VLP were characterized, including glycosylation profiles of glycoprotein subunits GP1 and GP2, and structural compartmentalization of each polypeptide. The host cell protein component of LASV VLP was also partially analyzed, namely glycoprotein incorporation, though the identity of these proteins remain unknown. All combinations of LASV Z, GPC, and NP proteins that generated VLP did not incorporate host cell ribosomes, a known component of native arenaviral particles, despite detection of small RNA species packaged into pseudoparticles. Although VLP did not contain the same host cell components as the native

  1. Multifield measurement of magnetic fluctuation-induced particle flux in a high-temperature toroidal plasma

    Science.gov (United States)

    Lin, L.; Ding, W. X.; Brower, D. L.

    2016-12-01

    Magnetic fluctuation-induced particle transport is explored in the high-temperature, high-beta interior of the Madison symmetric torus (MST) reversed-field pinch by performing a multifield measurement of the correlated product of magnetic and density fluctuations associated with global resistive tearing modes. Local density fluctuations are obtained by inverting the line-integrated interferometry data after resolving the mode helicity through correlation techniques. The local magnetic and current density fluctuations are then reconstructed using a parameterized fit of Faraday-effect polarimetry measurements. Reconstructed 2D images of density and current density perturbations in a poloidal cross section exhibit significantly different spatial structure. Combined with their relative phase, the magnetic-fluctuation-induced particle transport flux and its spatial distribution are resolved. The convective magnetic fluctuation-induced particle flux profile is measured for both standard and high-performance plasmas in MST with tokamak-like confinement, showing large reduction in the flux during improved confinement.

  2. Theoretical predictions for spatially-focused heating of magnetic nanoparticles guided by magnetic particle imaging field gradients

    Science.gov (United States)

    Dhavalikar, Rohan; Rinaldi, Carlos

    2016-12-01

    Magnetic nanoparticles in alternating magnetic fields (AMFs) transfer some of the field's energy to their surroundings in the form of heat, a property that has attracted significant attention for use in cancer treatment through hyperthermia and in developing magnetic drug carriers that can be actuated to release their cargo externally using magnetic fields. To date, most work in this field has focused on the use of AMFs that actuate heat release by nanoparticles over large regions, without the ability to select specific nanoparticle-loaded regions for heating while leaving other nanoparticle-loaded regions unaffected. In parallel, magnetic particle imaging (MPI) has emerged as a promising approach to image the distribution of magnetic nanoparticle tracers in vivo, with sub-millimeter spatial resolution. The underlying principle in MPI is the application of a selection magnetic field gradient, which defines a small region of low bias field, superimposed with an AMF (of lower frequency and amplitude than those normally used to actuate heating by the nanoparticles) to obtain a signal which is proportional to the concentration of particles in the region of low bias field. Here we extend previous models for estimating the energy dissipation rates of magnetic nanoparticles in uniform AMFs to provide theoretical predictions of how the selection magnetic field gradient used in MPI can be used to selectively actuate heating by magnetic nanoparticles in the low bias field region of the selection magnetic field gradient. Theoretical predictions are given for the spatial decay in energy dissipation rate under magnetic field gradients representative of those that can be achieved with current MPI technology. These results underscore the potential of combining MPI and higher amplitude/frequency actuation AMFs to achieve selective magnetic fluid hyperthermia (MFH) guided by MPI.

  3. Particle acceleration by fluctuating electric fields at a magnetic field null point

    CERN Document Server

    Petkaki, P

    2007-01-01

    Particle acceleration consequences from fluctuating electric fields superposed on an X-type magnetic field in collisionless solar plasma are studied. Such a system is chosen to mimic generic features of dynamic reconnection, or the reconnective dissipation of a linear disturbance. We explore numerically the consequences for charged particle distributions of fluctuating electric fields superposed on an X-type magnetic field. Particle distributions are obtained by numerically integrating individual charged particle orbits when a time varying electric field is superimposed on a static X-type neutral point. This configuration represents the effects of the passage of a generic MHD disturbance through such a system. Different frequencies of the electric field are used, representing different possible types of wave. The electric field reduces with increasing distance from the X-type neutral point as in linear dynamic magnetic reconnection. The resulting particle distributions have properties that depend on the ampli...

  4. Particle Diffusion and Acceleration by Shock Wave in Magnetized Filamentary Turbulence

    CERN Document Server

    Honda, M; Honda, Mitsuru; Honda, Yasuko S.

    2005-01-01

    We expand the off-resonant scattering theory for particle diffusion in magnetized current filaments that can be typically compared to astrophysical jets, including active galactic nucleus jets. In a high plasma beta region where the directional bulk flow is a free-energy source for establishing turbulent magnetic fields via current filamentation instabilities, a novel version of quasi-linear theory to describe the diffusion of test particles is proposed. The theory relies on the proviso that the injected energetic particles are not trapped in the small-scale structure of magnetic fields wrapping around and permeating a filament but deflected by the filaments, to open a new regime of the energy hierarchy mediated by a transition compared to the particle injection. The diffusion coefficient derived from a quasi-linear type equation is applied to estimating the timescale for the stochastic acceleration of particles by the shock wave propagating through the jet. The generic scalings of the achievable highest ener...

  5. On The Relativistic Classical Motion of a Radiating Spinning Particle in a Magnetic Field

    CERN Document Server

    Kar, Arnab

    2010-01-01

    We propose classical equations of motion for a charged particle with magnetic moment, taking radiation reaction into account. This generalizes the Landau-Lifshitz equations for the spinless case. In the special case of spin-polarized motion in a constant magnetic field (synchrotron motion) we verify that the particle does lose energy. Previous proposals did not predict dissipation of energy and also suffered from runaway solutions analogous to those of the Lorentz-Dirac equations of motion.

  6. On the relativistic classical motion of a radiating spinning particle in a magnetic field

    Science.gov (United States)

    Kar, Arnab; Rajeev, S. G.

    2011-04-01

    We propose classical equations of motion for a charged particle with magnetic moment, taking radiation reaction into account. This generalizes the Landau-Lifshitz equations for the spinless case. In the special case of spin-polarized motion in a constant magnetic field (synchrotron motion) we verify that the particle does lose energy. Previous proposals did not predict dissipation of energy and also suffered from runaway solutions analogous to those of the Lorentz-Dirac equations of motion.

  7. Synthesis of Co/Co3O4 Nanocomposite Particles Relevant to Magnetic Field Processing

    DEFF Research Database (Denmark)

    Srivastava, A.K.; Madhavi, S.; Menon, Mohan

    2010-01-01

    Co/Co3O4 nanocomposite particles of various morphologies were synthesized by the reverse micelle technique. Equiaxed, rod and faceted crystals with rectangular, pentagonal and hexagonal cross sections were observed. Annealing resulted in the formation of a composite of cobalt oxide (Co3O4) and fcc...... cobalt (Co). Removal of boron residues from the final product was established by surface characterization. Magnetic moment of these nanocomposite particles is relevant to magnetic field processing....

  8. Is the 3-D magnetic null point with a convective electric field an efficient particle accelerator?

    Science.gov (United States)

    Guo, J.-N.; Büchner, J.; Otto, A.; Santos, J.; Marsch, E.; Gan, W.-Q.

    2010-04-01

    Aims: We study the particle acceleration at a magnetic null point in the solar corona, considering self-consistent magnetic fields, plasma flows and the corresponding convective electric fields. Methods: We calculate the electromagnetic fields by 3-D magnetohydrodynamic (MHD) simulations and expose charged particles to these fields within a full-orbit relativistic test-particle approach. In the 3-D MHD simulation part, the initial magnetic field configuration is set to be a potential field obtained by extrapolation from an analytic quadrupolar photospheric magnetic field with a typically observed magnitude. The configuration is chosen so that the resulting coronal magnetic field contains a null. Driven by photospheric plasma motion, the MHD simulation reveals the coronal plasma motion and the self-consistent electric and magnetic fields. In a subsequent test particle experiment the particle energies and orbits (determined by the forces exerted by the convective electric field and the magnetic field around the null) are calculated in time. Results: Test particle calculations show that protons can be accelerated up to 30 keV near the null if the local plasma flow velocity is of the order of 1000 km s-1 (in solar active regions). The final parallel velocity is much higher than the perpendicular velocity so that accelerated particles escape from the null along the magnetic field lines. Stronger convection electric field during big flare explosions can accelerate protons up to 2 MeV and electrons to 3 keV. Higher initial velocities can help most protons to be strongly accelerated, but a few protons also run the risk to be decelerated. Conclusions: Through its convective electric field and due to magnetic nonuniform drifts and de-magnetization process, the 3-D null can act as an effective accelerator for protons but not for electrons. Protons are more easily de-magnetized and accelerated than electrons because of their larger Larmor radii. Notice that macroscopic MHD

  9. ORBXYZ: A 3D single-particle orbit code for following charged particle trajectories in equilibrium magnetic fields

    Science.gov (United States)

    Anderson, D. V.; Cohen, R. H.; Ferguson, J. R.; Johnston, B. M.; Sharp, C. B.; Willmann, P. A.

    1981-06-01

    The single particle orbit code, TIBRO, was modified extensively to improve the interpolation methods used and to allow use of vector potential fields in the simulation of charged particle orbits on a 3D domain. A 3D cubic B-spline algorithm is used to generate spline coefficients used in the interpolation. Smooth and accurate field representations are obtained. When vector potential fields are used, the 3D cubic spline interpolation formula analytically generates the magnetic field used to push the particles. This field has del.BETA = 0 to computer roundoff. When magnetic induction is used the interpolation allows del.BETA does not equal 0, which can lead to significant nonphysical results. Presently the code assumes quadrupole symmetry, but this is not an essential feature of the code and could be easily removed for other applications.

  10. Improving heat generation of magnetic nanoparticles by pre-orientation of particles in a static three tesla magnetic field

    Science.gov (United States)

    Beck, Mathias M.; Lammel, Christian; Gleich, Bernhard

    2017-04-01

    Inductive heating of electrically insulating materials like fiberglass reinforced thermoplastics (FRTP) without susceptors is not possible. However, due to their low thermal conductivity a volumetric heat generation method is advisable to reach short heating times to melt this material for reshaping. This can be done with magnetic nanoparticles as susceptors within the thermoplastic of the FRTP using Néel relaxation. During the heating process the particle's magnetic moment rotates with the field while the particle itself is fixed within the thermoplastic. Therefore the heat dissipation of each particle depends on its orientation within the field. To achieve the maximum heat generation of the particles we pre-oriented the particles within a plastic at the best angle to the applied AC field for induction. To do this, five mass percent nanoparticles were dispersed in an epoxy resin, which was then hardened at room temperature in a static three Tesla magnetic field. After its solidification the heating behavior of the sample was compared to a reference sample, which was hardened without a field. The oriented particles showed an increased heating rate when oriented parallel to the applied AC field. The absorption rate was 3.3 times as high as the undirected reference sample. When the alternating electromagnetic field was perpendicular to the oriented particles, the specific absorption rate was similar to that of the reference sample. We compare this result with theory and with calculations from literature, and conduct a numerical simulation.

  11. Development of Single-side Magnet Array for Super Paramagnetic Nano-particle Targeting

    Directory of Open Access Journals (Sweden)

    Wei He

    2014-04-01

    Full Text Available Permanent magnets are interesting for the use in magnetic drug targeting devices. The magnetic fields and forces with distances from magnets have limited the depth of targeting. Producing greater forces at deep depth by optimally designed magnet arrays would allow treatment of a wider class of patients. In this study, we present a design of a permanent magnet array for deep magnetic capture of super paramagnetic iron oxide nano-particles, which consists of an array of 3 individual bar permanent magnet positioned to achieve a reasonably magnitude magnetic field and its gradient within a deeply region. These configurations were simulated with two-dimensional finite-element methods. The super paramagnetic iron oxide nano-particles were adopted Fe3O4 particles with diameter 40 nm by chemical co-precipitation method. Performance factors were defined to relate magnetic field force with mass. The field strength and gradient were measured by a Hall probe and agreed well with the simulations.

  12. The Generation of a Large-Scale Galactic Magnetic Field by Electric Currents of Energetic Particles

    Science.gov (United States)

    Dolginov, A. Z.; Toptygin, I. N.

    2003-06-01

    We consider the generation of a magnetic field in the Galaxy by the electric currents excited by cosmic-ray particles in the disk and halo. We assume that the sources of relativistic particles are distributed continuously and uniformly in the Galactic disk, their total power is equal to the observed value, and the particles themselves undergo anisotropic diffusion in a homogeneous medium. We take into account the differential rotation of the Galactic disk but disregard the turbulence gyrotropy (the alpha-effect). The strength of the generated magnetic field in our model is shown to strongly depend on the symmetry of the relativistic proton and thermal electron diffusion tensors, as well as on the relations between the tensor components. In particular, if the diffusion is isotropic, then no magnetic field is generated. For the independent tensor components estimated from observed parameters of the Galactic medium and with a simultaneous allowance made for the turbulent field dissipation processes, the mechanism under consideration can provide an observable magnetic-field strength of the order of several microgauss. This mechanism does not require any seed magnetic field, which leads us to suggest that relativistic particles can give an appreciable and, possibly, determining contribution to the formation of the global Galactic magnetic field. However, a final answer can be obtained only from a nonlinear self-consistent treatment, in which the symmetry and magnitude of the particle diffusion tensor components should be determined together with the calculation of the magnetic field.

  13. Modeling of magnetic hystereses in soft MREs filled with NdFeB particles

    Science.gov (United States)

    Kalina, K. A.; Brummund, J.; Metsch, P.; Kästner, M.; Borin, D. Yu; Linke, J. M.; Odenbach, S.

    2017-10-01

    Herein, we investigate the structure-property relationships of soft magnetorheological elastomers (MREs) filled with remanently magnetizable particles. The study is motivated from experimental results which indicate a large difference between the magnetization loops of soft MREs filled with NdFeB particles and the loops of such particles embedded in a comparatively stiff matrix, e.g. an epoxy resin. We present a microscale model for MREs based on a general continuum formulation of the magnetomechanical boundary value problem which is valid for finite strains. In particular, we develop an energetically consistent constitutive model for the hysteretic magnetization behavior of the magnetically hard particles. The microstructure is discretized and the problem is solved numerically in terms of a coupled nonlinear finite element approach. Since the local magnetic and mechanical fields are resolved explicitly inside the heterogeneous microstructure of the MRE, our model also accounts for interactions of particles close to each other. In order to connect the microscopic fields to effective macroscopic quantities of the MRE, a suitable computational homogenization scheme is used. Based on this modeling approach, it is demonstrated that the observable macroscopic behavior of the considered MREs results from the rotation of the embedded particles. Furthermore, the performed numerical simulations indicate that the reversion of the sample’s magnetization occurs due to a combination of particle rotations and internal domain conversion processes. All of our simulation results obtained for such materials are in a good qualitative agreement with the experiments.

  14. Magnetic properties of 3D nanocomposites consisting of an opal matrix with embedded spinel ferrite particles

    Science.gov (United States)

    Rinkevich, A. B.; Korolev, A. V.; Samoylovich, M. I.; Kleshcheva, S. M.; Perov, D. V.

    2016-02-01

    The magnetic properties of 3D nanocomposites representing Mn-Zn, Ni-Zn, Co-Zn, La-Co-Zn, and Nd-Co-Zn spinel ferrite particles embedded in the interspherical spaces of opal matrices are studied. Experimental data are obtained in the temperature interval 2-300 K by measuring the magnetization at a static magnetic field strength of up to 50 kOe and the ac magnetic susceptibility at an alternating magnetic field amplitude of 4 kOe and a frequency of 80 Hz.

  15. Impact of strong magnetic fields on collision mechanism for transport of charged particles

    CERN Document Server

    Bostan, Mihai

    2012-01-01

    One of the main applications in plasma physics concerns the energy production through thermo-nuclear fusion. The controlled fusion is achieved by magnetic confinement i.e., the plasma is confined into a toroidal domain (tokamak) under the action of huge magnetic fields. Several models exist for describing the evolution of strongly magnetized plasmas, most of them by neglecting the collisions between particles. The subject matter of this paper is to investigate the effect of large magnetic fields with respect to a collision mechanism. We consider here linear collision Boltzmann operators and derive, by averaging with respect to the fast cyclotronic motion due to strong magnetic forces, their effective collision kernels.

  16. Impact of Strong Magnetic Fields on Collision Mechanism for Transport of Charged Particles

    Science.gov (United States)

    Bostan, Mihai; Gamba, Irene M.

    2012-09-01

    One of the main applications in plasma physics concerns the energy production through thermo-nuclear fusion. The controlled fusion is achieved by magnetic confinement i.e., the plasma is confined into a toroidal domain (tokamak) under the action of huge magnetic fields. Several models exist for describing the evolution of strongly magnetized plasmas, most of them by neglecting the collisions between particles. The subject matter of this paper is to investigate the effect of large magnetic fields with respect to a collision mechanism. We consider here linear collision Boltzmann operators and derive, by averaging with respect to the fast cyclotronic motion due to strong magnetic forces, their effective collision kernels.

  17. Motion behavior of particles in air-solid magnetically stabilized fluidized beds for separation

    Institute of Scientific and Technical Information of China (English)

    Song Shulei; Zhao Yuemin; Luo Zhenfu; Tang Ligang

    2012-01-01

    In order to study the settling mechanism of particles in an air-solid magnetically stabilized fluidized bed (MSFB) for separation,we carried out free settling and quasi-zero settling tests on the tracing particles.The results show that the main resistance forces as the tracing particles settled in an air-solid MSFB were motion resistance force and yield force.The motion resistance and yield forces greatly hindered the free settling of the particles by greatly decreasing the acceleration for settling process of the particles.The acceleration decreased from 3022.62 cm/s2 to zero in 0.1 s,and in the end,the particles stopped in the air-solid MSFB.The yield force on particles increased with increasing the magnetic field intensity,resulting in decrease of the quasi-zero settling displacement.However,the yield force on particles decreased with increasing the fluidized air velocity,leading to increase of the quasi-zero settling displacement.When the structure and operating parameters of the air-solid MSFB were set up,the yield stress on particles stopped in an air-solid MSFB was a function of diameter and density of particles.The settling displacements of equal diameter particles increased with increasing their densities,and the settling displacements of equal density particles increased with increasing their diameters.

  18. Intraluminal magnetisation of bowel by ferromagnetic particles for retraction and manipulation by magnetic probes.

    Science.gov (United States)

    Wang, Z; André, P; McLean, D; Brown, S I; Florence, G J; Cuschieri, A

    2014-11-01

    Feasibility studies are needed to demonstrate that safe and effective manipulation of bowel during Minimal Access Surgery (MAS) can be obtained by use of magnetic force. This paper characterises two classes of magnetic particles: stainless steel microparticles (SS-μPs) and iron oxide nanoparticles (IO-nPs) in terms of their magnetisation, chemical composition, crystallinity, morphology and size distribution. Both magnetic particles were dispersed in a high viscosity biological liquid for intraluminal injection of bowel. Ex vivo porcine bowel segments were then retracted by permanent magnetic probes of 5.0 and 10mm diameter. Strong retraction forces reaching 6N maximum were obtained by magnetic fluid based on dispersion of SS-μPs. In contrast, the IO-nP-based magnetic liquid generated less attraction force, due to both lower magnetic and solution properties of the IO-nPs. The comparison of the two particles allowed the identification of the rules to engineer the next generation of particles. The results with SS-μPs provide proof on concept that intraluminal injection of magnetic fluid can generate sufficient force for efficient bowel retraction. Thereafter we shall carry out in vivo animal studies for efficacy and safety of both types of ferrofluids.

  19. Particle in short-range potential in two dimensional structure in magnetic field

    NARCIS (Netherlands)

    Andreev, S. P.; Pavlova, T. V.

    2006-01-01

    An exact solution is given for the problem of determining the ground state of a charge particle in a zero range force field located in a quantum well and in a magnetic field. The dependence of the electron's ground state on the potential depth and the magnetic field is investigated in a semiconducto

  20. Tuning the Colloidal Crystal Structure of Magnetic Particles by External Field

    NARCIS (Netherlands)

    Pal, Antara; Malik, Vikash; He, Le; Erne, Ben H.; Yin, Yadong; Kegel, Willem K.; Petukhov, A. V.

    2015-01-01

    Manipulation of the self-assembly of magnetic colloidal particles by an externally applied magnetic field paves a way toward developing novel stimuli responsive photonic structures. Using microradian X-ray scattering technique we have investigated the different crystal structures exhibited by self-a

  1. World's largest particle accelerator nears completion with last quadripolar magnet installed

    CERN Multimedia

    2007-01-01

    "The last quadripolar magnet was brought down into the tunnel of the world's largest particle accelerator; the CERN's1 LHC, or Large Hadron Collider. This magnet is part of a series of 392 units which will ensure that the beams are kept on track all along their trajectory through the tunnel." (1 page)

  2. Anomalous Particle Size Dependence of Magnetic Relaxation Phenomena in Goethite Nanoparticles

    DEFF Research Database (Denmark)

    Frandsen, Cathrine; Madsen, Daniel Esmarch; Boothroyd, Chris B.

    2015-01-01

    By use of Mossbauer spectroscopy we have studied the magnetic properties of samples of goethite nanoparticles with different particle size. The spectra are influenced by fluctuations of the magnetization directions, but the size dependence is not in accordance with the Neel-Brown expression for s...

  3. Development of a flaw detection material for the magnetic particle method

    Science.gov (United States)

    Chesnokova, A. A.; Kalayeva, S. Z.; Ivanova, V. A.

    2017-08-01

    The issues of increasing the effectiveness of the magnetic particle method of nondestructive testing by using a new flaw detection material is considered in the paper. The requirements for flaw detection materials are determined, which ensure the effectiveness of the inspection method. A new flaw detection material - magnetic fluids from iron-containing waste products - has been developed.

  4. Nearly finished LHC particle smasher breaks at support point to magnets

    CERN Multimedia

    Atkins, William

    2007-01-01

    "The proton-proton Large Hadron Collider (LHC) particle accelerator is being built at Geneva, Switzerland's CERN - the world's largest particle physics laboratory. However, a support assembly structure for critical magnets failed while being tested on March 27, 2007." (1/2 page)

  5. Magnetic trapping of superconducting submicron particles produced by laser ablation in superfluid helium

    Science.gov (United States)

    Takahashi, Yuta; Suzuki, Junpei; Yoneyama, Naoya; Tokawa, Yurina; Suzuki, Nobuaki; Matsushima, Fusakazu; Kumakura, Mitsutaka; Ashida, Masaaki; Moriwaki, Yoshiki

    2017-02-01

    We produced spherical superconducting submicron particles by laser ablation of their base metal tips in superfluid helium, and trapped them using a quadrupole magnetic field owing to the diamagnetism caused by the Meissner effect. We also measured their critical temperatures of superconductivity, by observing the threshold temperatures for the confinement of superconducting submicron particles in the trap.

  6. Nearly finished LHC particle smasher breaks at support point to magnets

    CERN Multimedia

    Atkins, William

    2007-01-01

    "The proton-proton Large Hadron Collider (LHC) particle accelerator is being built at Geneva, Switzerland's CERN - the world's largest particle physics laboratory. However, a support assembly structure for critical magnets failed while being tested on March 27, 2007." (1/2 page)

  7. Stochastic Ripple Diffusion of Energetic Particles in Reversed Magnetic Shear Tokamak

    Institute of Scientific and Technical Information of China (English)

    GAO Qing-Di; LONG Yong-Xing

    2004-01-01

    @@ The stochastic ripple diffusion is investigated in a realistic reversed magnetic shear discharge. Rippled field produces variations in the velocity of trapped particles leading to excursion of the tip position for successive banana bounces. When the excursion is large enough, the trapped energetic particles are lost rapidly via stochastic banana diffusion.

  8. Grid Connected Power Supplies for Particle Accelerator Magnets

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Ørndrup

    and smaller converter size. A high efficiency converter based on Silicon Carbide switching devices is also presented exhibiting above 96 % efficiency for the entire power range. Finally reliability issues are considered as the reliability of a particle accelerator supply is of utmost importance. Particle...

  9. Surface functionalized nano-magnetic particles for wastewater treatment: adsorption and desorption of mercury.

    Science.gov (United States)

    Tri, Pham Minh; Khim, Kwa Soo; Hidajat, K; Uddin, M S

    2009-02-01

    The present study deals with adsorption and desorption of mercury on surface functionalized nano-magnetic particles. The nano-magnetic particles (Fe3O4) were synthesized by chemical precipitation of Fe2+ and Fe3+ salts at 80 degrees C at alkaline condition and inert atmosphere. The particle surface was then functionalized in two different ways: surface charge controlled by solution pH and coating the surface with polymer (vinylpyrrolidone) with thiodiglycolic acid as the primary surfactant and 4-vinylaniline as the secondary surfactant. It was found that the adsorption of mercury was pH dependent and maximum adsorption occurred at pH of 7.5 with bare particles and at pH 10 for polymer grafted particles. Maximum adsorption of mercury was found to be 280 mg/g particle.

  10. Engineering and characterization of mesoporous silica-coated magnetic particles for mercury removal from industrial effluents

    Science.gov (United States)

    Dong, Jie; Xu, Zhenghe; Wang, Feng

    2008-03-01

    Mesoporous silica coatings were synthesized on dense liquid silica-coated magnetite particles using cetyl-trimethyl-ammonium chloride (CTAC) as molecular templates, followed by sol-gel process. A specific surface area of the synthesized particles as high as 150 m 2/g was obtained. After functionalization with mercapto-propyl-trimethoxy-silane (MPTS) through silanation reaction, the particles exhibited high affinity of mercury in aqueous solutions. Atomic force microscopy (AFM), zeta potential measurement, thermal gravimetric analysis (TGA), analytical transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and atomic absorption spectroscopy (AAS) were used to characterize the synthesis processes, surface functionalization, and mercury adsorption on the synthesized magnetite particles. The loading capacity of the particles for mercury was determined to be as high as 14 mg/g at pH 2. A unique feature of strong magnetism of the synthesized nanocomposite particles makes the subsequent separation of the magnetic sorbents from complex multiphase suspensions convenient and effective.

  11. Calculation, display, and analysis of the nature of nonsymmetric nuclear magnetic resonance shielding tensors: Application to three-membered rings

    Science.gov (United States)

    Hansen, Aage E.; Bouman, Thomas D.

    1989-09-01

    The components of the full nuclear shielding tensor are analyzed with particular regard to the origins of the antisymmetric component of the shielding of nuclei at low-symmetry molecular sites. As an aid we propose the study and display of the shielding response vector, i.e., the nuclear shielding field per unit applied magnetic field. The analysis is based on ab initio calculations in the localized orbital-local origin method for cyclopropane, cyclopropene, ethylene oxide, ethylene imine, and diazirine, and also includes a discussion of the mechanism for the large antisymmetric component predicted for the unsaturated nuclei in cyclopropene and diazirine, both in terms of bond and lone pair contributions and in terms of a decomposition of the dominant paramagnetic contributions into molecular point group species. Display of the component of the shielding vector parallel to the applied field is shown to be a valuable alternative to the common ellipsoid representations. Display of the components perpendicular to the applied field provides a picture of the relation of the antisymmetry to molecular structure and suggests its direct observation through monitoring the perpendicular response. Finally, we show that, contrary to a recent claim, the eigensolutions of the full tensor in the presence of antisymmetry play no role in the observed anisotropies.

  12. Exact Green function for neutral Pauli-Dirac particle with anomalous magnetic momentum in linear magnetic field

    Science.gov (United States)

    Merdaci, Abdeldjalil; Jellal, Ahmed; Chetouani, Lyazid

    2017-09-01

    It is shown that the propagator of the neutral Pauli-Dirac particle with an anomalous magnetic moment μ in an external linear magnetic field B(x) = B +B‧ x is the causal Green function Sc(xb ,xa) of the Pauli-Dirac equation. The corresponding Green function is calculated via path integral method in global projection, giving rise to the exact eigenspinor expressions. The effective action is used to explicitly determine the production rate in vacuum of neutral Dirac particle in terms of B‧ and μ, which is B independent.

  13. Iron oxide nanoparticle-micelles (ION-micelles for sensitive (molecular magnetic particle imaging and magnetic resonance imaging.

    Directory of Open Access Journals (Sweden)

    Lucas W E Starmans

    Full Text Available BACKGROUND: Iron oxide nanoparticles (IONs are a promising nanoplatform for contrast-enhanced MRI. Recently, magnetic particle imaging (MPI was introduced as a new imaging modality, which is able to directly visualize magnetic particles and could serve as a more sensitive and quantitative alternative to MRI. However, MPI requires magnetic particles with specific magnetic properties for optimal use. Current commercially available iron oxide formulations perform suboptimal in MPI, which is triggering research into optimized synthesis strategies. Most synthesis procedures aim at size control of iron oxide nanoparticles rather than control over the magnetic properties. In this study, we report on the synthesis, characterization and application of a novel ION platform for sensitive MPI and MRI. METHODS AND RESULTS: IONs were synthesized using a thermal-decomposition method and subsequently phase-transferred by encapsulation into lipidic micelles (ION-Micelles. Next, the material and magnetic properties of the ION-Micelles were analyzed. Most notably, vibrating sample magnetometry measurements showed that the effective magnetic core size of the IONs is 16 nm. In addition, magnetic particle spectrometry (MPS measurements were performed. MPS is essentially zero-dimensional MPI and therefore allows to probe the potential of iron oxide formulations for MPI. ION-Micelles induced up to 200 times higher signal in MPS measurements than commercially available iron oxide formulations (Endorem, Resovist and Sinerem and thus likely allow for significantly more sensitive MPI. In addition, the potential of the ION-Micelle platform for molecular MPI and MRI was showcased by MPS and MRI measurements of fibrin-binding peptide functionalized ION-Micelles (FibPep-ION-Micelles bound to blood clots. CONCLUSIONS: The presented data underlines the potential of the ION-Micelle nanoplatform for sensitive (molecular MPI and warrants further investigation of the Fib

  14. Structural changes in microferrogels cross-linked by magnetically anisotropic particles

    Science.gov (United States)

    Ryzhkov, A. V.; Raikher, Yu. L.

    2017-06-01

    Chaining of magnetic nanoparticles in a microscopic ferrogel (MFG) due to interparticle interaction and external field is analyzed by the coarse-grained molecular dynamics. The embedded nanoparticles, unlike existing conventional models, are assumed to possess uniaxial magnetic anisotropy. By that, the consideration is brought closer to reality. Evolution of particle chains, both in length and straightness, is handled with the aid of ;axial; radial distribution function that is sensitive to orientation of the aggregates. The effect of the particle magnetic anisotropy on the structural alterations as well as on volume changes of MFGs is demonstrated.

  15. Energetic Particles inside Magnetic Clouds: a tentative search for their origin

    Science.gov (United States)

    Rodriguez-Pacheco, Javier

    During solar activity cycle 21st maximum, the instrumentation aboard ISEE-3 spacecraft observed many ener getic particles events, several of them associated with Magnetic Clouds (MCs). In this paper, we focus our study on the December 19th 1980 event, which was related with an MC that showed one of the most intense magnetic field strength ever observed. We have studied the energetic particle (36 keV - 1,6 MeV) spectra and directional distribution evolutions just before, inside and after the MC passage, with the aim of finding the origin of the energetic particles detected inside the MC.

  16. Activity of an enzyme immobilized on superparamagnetic particles in a rotational magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Mizuki, Toru; Watanabe, Noriyuki; Nagaoka, Yutaka [Bio-Nano Electronics Research Centre, Toyo University, Saitama 350-8585 (Japan); Fukushima, Tadamasa [Shimadzu GLC Ltd., Phenomenex Support Centre, Tokyo 110-0016 (Japan); Morimoto, Hisao; Usami, Ron [Bio-Nano Electronics Research Centre, Toyo University, Saitama 350-8585 (Japan); Maekawa, Toru, E-mail: maekawa@toyonet.toyo.ac.jp [Bio-Nano Electronics Research Centre, Toyo University, Saitama 350-8585 (Japan)

    2010-03-19

    We immobilize {alpha}-amylase extracted from Bacillus Iicheniformis on the surfaces of superparamagnetic particles and investigate the effect of a rotational magnetic field on the enzyme's activity. We find that the activity of the enzyme molecules immobilized on superparamagnetic particles increases in the rotational magnetic field and reaches maximum at a certain frequency. We clarify the effect of the cluster structures formed by the superparamagnetic particles on the activity. Enzyme reactions are enhanced even in a tiny volume of solution using the present method, which is very important for the development of efficient micro reactors and micro total analysis systems ({mu}-TAS).

  17. Search for exotic stable charged particles and magnetic monopoles at ALICE

    CERN Document Server

    Bader, Maria Karolina Margit

    2014-01-01

    The report describes an exploratory study of beyond the standard model particles like exotic stable charged particles and magnetic monopoles at ALICE. These particles typically posses very high masses and are reconstructable in high energy and high momentum regions. A procedure to obtain the mass spectra from the Time-of-Flight detector (TOF) and the Time-Projection Chamber (TPC) is described as well as a analysis of the TOF background signal. In addition the possibility to search for magnetic monopoles in the data and expected structures of free quarks are investigated.

  18. Self-organized magnetic particles to tune the mechanical behavior of a granular system

    Science.gov (United States)

    Cox, Meredith; Wang, Dong; Barés, Jonathan; Behringer, Robert P.

    2016-09-01

    Above a certain density a granular material jams. This property can be controlled by either tuning a global property, such as the packing fraction or by applying shear strain, or at the micro-scale by tuning grain shape, inter-particle friction or externally controlled organization. Here, we introduce a novel way to change a local granular property by adding a weak anisotropic magnetic interaction between particles. We measure the evolution of the pressure, P, and coordination number, Z, for a packing of 2D photo-elastic disks, subject to uniaxial compression. A fraction R m of the particles have embedded cuboidal magnets. The strength of the magnetic interactions between particles is too weak to have a strong direct effect on P or Z when the system is jammed. However, the magnetic interactions play an important role in the evolution of latent force networks when systems containing a large enough fraction of the particles with magnets are driven through unjammed to jammed states. In this case, a statistically stable network of magnetic chains self-organizes before jamming and overlaps with force chains once jamming occurs, strengthening the granular medium. This property opens a novel way to control mechanical properties of granular materials.

  19. Simultaneous steering and imaging of magnetic particles using MRI toward delivery of therapeutics

    Science.gov (United States)

    Felfoul, Ouajdi; Becker, Aaron T.; Fagogenis, Georgios; Dupont, Pierre E.

    2016-01-01

    Magnetic resonance navigation (MRN) offers the potential for real-time steering of drug particles and cells to targets throughout the body. In this technique, the magnetic gradients of an MRI scanner perform image-based steering of magnetically-labelled therapeutics through the vasculature and into tumours. A major challenge of current techniques for MRN is that they alternate between pulse sequences for particle imaging and propulsion. Since no propulsion occurs while imaging the particles, this results in a significant reduction in imaging frequency and propulsive force. We report a new approach in which an imaging sequence is designed to simultaneously image and propel particles. This sequence provides a tradeoff between maximum propulsive force and imaging frequency. In our reported example, the sequence can image at 27 Hz while still generating 95% of the force produced by a purely propulsive pulse sequence. We implemented our pulse sequence on a standard clinical scanner using millimetre-scale particles and demonstrated high-speed (74 mm/s) navigation of a multi-branched vascular network phantom. Our study suggests that the magnetic gradient magnitudes previously demonstrated to be sufficient for pure propulsion of micron-scale therapeutics in magnetic resonance targeting (MRT) could also be sufficient for real-time steering of these particles. PMID:27666666

  20. Polydopamine-Coated Magnetic Composite Particles with an Enhanced Photothermal Effect.

    Science.gov (United States)

    Zheng, Rui; Wang, Sheng; Tian, Ye; Jiang, Xinguo; Fu, Deliang; Shen, Shun; Yang, Wuli

    2015-07-29

    Recently, photothermal therapy (PTT) that utilizes photothermal conversion (PTC) agents to ablate cancer under near-infrared (NIR) irradiation has attracted a growing amount of attention because of its excellent therapeutic efficacy and improved target selectivity. Therefore, exploring novel PTC agents with an outstanding photothermal effect is a current research focus. Herein, we reported a polydopamine-coated magnetic composite particle with an enhanced PTC effect, which was synthesized simply through coating polydopamine (PDA) on the surface of magnetic Fe3O4 particles. Compared with magnetic Fe3O4 particles and PDA nanospheres, the core-shell nanomaterials exhibited an increased NIR absorption, and thus, an enhanced photothermal effect was obtained. We demonstrated the in vitro and in vivo effects of the photothermal therapy using our composite particles and their ability as a contrast agent in the T2-weighted magnetic resonance imaging. These results indicated that the multifunctional composite particles with enhanced photothermal effect are superior to magnetic Fe3O4 particles and PDA nanospheres alone.

  1. In vivo liver visualizations with magnetic particle imaging based on the calibration measurement approach

    Science.gov (United States)

    Dieckhoff, J.; Kaul, M. G.; Mummert, T.; Jung, C.; Salamon, J.; Adam, G.; Knopp, T.; Ludwig, F.; Balceris, C.; Ittrich, H.

    2017-05-01

    Magnetic particle imaging (MPI) facilitates the rapid determination of 3D in vivo magnetic nanoparticle distributions. In this work, liver MPI following intravenous injections of ferucarbotran (Resovist®) was studied. The image reconstruction was based on a calibration measurement, the so called system function. The application of an enhanced system function sample reflecting the particle mobility and aggregation status of ferucarbotran resulted in significantly improved image reconstructions. The finding was supported by characterizations of different ferucarbotran compositions with the magnetorelaxometry and magnetic particle spectroscopy technique. For instance, similar results were obtained between ferucarbotran embedded in freeze-dried mannitol sugar and liver tissue harvested after a ferucarbotran injection. In addition, the combination of multiple shifted measurement patches for a joint reconstruction of the MPI data enlarged the field of view and increased the covering of liver MPI on magnetic resonance images noticeably.

  2. Particle size optimization of SrFe12O19 magnetic nanoparticles

    DEFF Research Database (Denmark)

    Ahlburg, Jakob

    2015-01-01

    Particle size optimization of SrFe12O19 magnetic nanoparticles. J. Ahlburg,a M. S. Músquiza, C. Zeuthena, S. Kjeldgaarda, M. Stingaciua, M. Christensena aCenter for Materials Crystallography, Departement of Chemistry & iNano, Aarhus University, Denmark Since the invention of the electric motor...... and the number of publications has grown exponentially for the last 50 years. [3] SrFe12O19 has excellent magnetic properties due to the high anisotropy of the unitcell and by making nanoparticles it is possible to have single magnetic domain particles. [4] This will greatly improve the energy product pr. Volume......, which is needed in small devices. When nanoparticles of SrFe12O19 are formed the growth is furthermore such that platelets are formed making them easy to stack when forming a bulk magnet. In these studies we want to control the size and shape of the particles by using a simple setup suitable for rapid...

  3. Immobilization of cellulases on magnetic particles to enable enzyme recycling during hydrolysis of lignocellulose

    DEFF Research Database (Denmark)

    Alftrén, Johan

    on commercial magnetic particles coated with streptavidin. The procedure enabled simultaneous purification and immobilization from crude cell lysate because of the very strong interaction and high affinity between biotin and streptavidin. A third method of immobilizing enzymes was employed in paper IV where two...... feedstocks containing insolubles. This could potentially be overcome by immobilizing the cellulases on magnetically susceptible particles. Consequently, the immobilized cellulases could be magnetically recovered and recycled for a new cycle of enzymatic hydrolysis of cellulose. The main objective...... of this thesis was to examine the possibility of immobilizing cellulases on magnetic particles in order to enable enzyme re-use. Studies at lab and pilot scale (20 L) were conducted using model and real substrates. In paper I and III beta-glucosidase or a whole cellulase mixture was covalently immobilized...

  4. Magnetic Dynamics of Fine Particles Studied by Inelastic Neutron Scattering

    DEFF Research Database (Denmark)

    Hansen, Mikkel Fougt; Bødker, Franz; Mørup, Steen;

    2000-01-01

    We give an introduction to inelastic neutron scattering and the dynamic scattering function for magnetic nanoparticles. Differences between ferromagnetic and antiferromagnetic nanoparticles are discussed and we give a review of recent results on ferromagnetic Fe nanoparticles and canted antiferro......We give an introduction to inelastic neutron scattering and the dynamic scattering function for magnetic nanoparticles. Differences between ferromagnetic and antiferromagnetic nanoparticles are discussed and we give a review of recent results on ferromagnetic Fe nanoparticles and canted...

  5. Modern Display Technologies and Applications

    Science.gov (United States)

    1982-01-01

    conventional tubes, LSI circuitry offers the possibility of correcting some of the deficiencies in electron-optic perform- ance and may lead to acceptable...certain ceramic materials such as PLZT (lead lanthanum zirconate titanate) can be utilized for display applications. PLZT is transparent in the visible...consuming power (3.8.12). 3.8.4.2 State of development, Magnetic particles have been made of polyethylene with powdered Strontium ferrite as a filler

  6. Acceleration of charged particles due to chaotic scattering in the combined black hole gravitational field and asymptotically uniform magnetic field

    CERN Document Server

    Stuchlík, Zdeněk

    2015-01-01

    To test the role of large-scale magnetic fields in accretion processes, we study dynamics of charged test particles in vicinity of a black hole immersed into an asymptotically uniform magnetic field. Using the Hamiltonian formalism of charged particle dynamics, we examine chaotic scattering in the effective potential related to the black hole gravitational field combined with the uniform magnetic field. Energy interchange between the translational and oscillatory modes od the charged particle dynamics provides mechanism for charged particle acceleration along the magnetic field lines. This energy transmutation is an attribute of the chaotic charged particle dynamics in the combined gravitational and magnetic fields only, the black hole rotation is not necessary for such charged particle acceleration. The chaotic scatter can cause transition to the motion along the magnetic field lines with small radius of the Larmor motion or vanishing Larmor radius, when the speed of the particle translational motion is larg...

  7. Clinically viable magnetic poly(lactide-co-glycolide) (PLGA) particles for MRI-based cell tracking

    Science.gov (United States)

    Granot, Dorit; Nkansah, Michael K.; Bennewitz, Margaret F.; Tang, Kevin S.; Markakis, Eleni A.; Shapiro, Erik M.

    2013-01-01

    Purpose To design, fabricate, characterize and in vivo assay clinically viable magnetic particles for MRI-based cell tracking. Methods PLGA encapsulated magnetic nano- and microparticles were fabricated. Multiple biologically relevant experiments were performed to assess cell viability, cellular performance and stem cell differentiation. In vivo MRI experiments were performed to separately test cell transplantation and cell migration paradigms, as well as in vivo biodegradation. Results Highly magnetic nano- (~100 nm) and microparticles (~1–2 μm) were fabricated. Magnetic cell labeling in culture occurred rapidly achieving 3–50 pg Fe/cell at 3 hrs for different particles types, and >100 pg Fe/cell after 10 hours, without the requirement of a transfection agent, and with no effect on cell viability. The capability of magnetically labeled mesenchymal or neural stem cells to differentiate down multiple lineages, or for magnetically labeled immune cells to release cytokines following stimulation, was uncompromised. An in vivo biodegradation study revealed that NPs degraded ~80% over the course of 12 weeks. MRI detected as few as 10 magnetically labeled cells, transplanted into the brains of rats. Also, these particles enabled the in vivo monitoring of endogenous neural progenitor cell migration in rat brains over 2 weeks. Conclusion The robust MRI properties and benign safety profile of these particles make them promising candidates for clinical translation for MRI-based cell tracking. PMID:23568825

  8. Development of Modeling and Simulation for Magnetic Particle Inspection Using Finite Elements

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jun-Youl [Iowa State Univ., Ames, IA (United States)

    2003-01-01

    Magnetic particle inspection (MPI) is a widely used nondestructive inspection method for aerospace applications essentially limited to experiment-based approaches. The analysis of MPI characteristics that affect sensitivity and reliability contributes not only reductions in inspection design cost and time but also improvement of analysis of experimental data. Magnetic particles are easily attracted toward a high magnetic field gradient. Selection of a magnetic field source, which produces a magnetic field gradient large enough to detect a defect in a test sample or component, is an important factor in magnetic particle inspection. In this work a finite element method (FEM) has been employed for numerical calculation of the MPI simulation technique. The FEM method is known to be suitable for complicated geometries such as defects in samples. This thesis describes the research that is aimed at providing a quantitative scientific basis for magnetic particle inspection. A new FEM solver for MPI simulation has been developed in this research for not only nonlinear reversible permeability materials but also irreversible hysteresis materials that are described by the Jiles-Atherton model. The material is assumed to have isotropic ferromagnetic properties in this research (i.e., the magnetic properties of the material are identical in all directions in a single crystal). In the research, with a direct current field mode, an MPI situation has been simulated to measure the estimated volume of magnetic particles around defect sites before and after removing any external current fields. Currently, this new MPI simulation package is limited to solving problems with the single current source from either a solenoid or an axial directional current rod.

  9. Development of Modeling and Simulation for Magnetic Particle Inspection Using Finite Elements

    Energy Technology Data Exchange (ETDEWEB)

    Jun-Youl Lee

    2003-05-31

    Magnetic particle inspection (MPI) is a widely used nondestructive inspection method for aerospace applications essentially limited to experiment-based approaches. The analysis of MPI characteristics that affect sensitivity and reliability contributes not only reductions in inspection design cost and time but also improvement of analysis of experimental data. Magnetic particles are easily attracted toward a high magnetic field gradient. Selection of a magnetic field source, which produces a magnetic field gradient large enough to detect a defect in a test sample or component, is an important factor in magnetic particle inspection. In this work a finite element method (FEM) has been employed for numerical calculation of the MPI simulation technique. The FEM method is known to be suitable for complicated geometries such as defects in samples. This thesis describes the research that is aimed at providing a quantitative scientific basis for magnetic particle inspection. A new FEM solver for MPI simulation has been developed in this research for not only nonlinear reversible permeability materials but also irreversible hysteresis materials that are described by the Jiles-Atherton model. The material is assumed to have isotropic ferromagnetic properties in this research (i.e., the magnetic properties of the material are identical in all directions in a single crystal). In the research, with a direct current field mode, an MPI situation has been simulated to measure the estimated volume of magnetic particles around defect sites before and after removing any external current fields. Currently, this new MPI simulation package is limited to solving problems with the single current source from either a solenoid or an axial directional current rod.

  10. Artifacts in field free line magnetic particle imaging in the presence of inhomogeneous and nonlinear magnetic fields

    Directory of Open Access Journals (Sweden)

    Medimagh Hanne

    2015-09-01

    Full Text Available Introduction: Magnetic Particle Imaging (MPI is an emerging medical imaging modality that detects super-paramagnetic particles exploiting their nonlinear magnetization response. Spatial encoding can be realized using a Field Free Line (FFL, which is generated, rotated and translated through the Field of View (FOV using a combination of magnetic gradient fields and homogeneous excitation fields. When scaling up systems and/or enlarging the FOV in comparison to the scanner bore, ensuring homogeneity and linearity of the magnetic fields becomes challenging. The present contribution describes the first comprehensive, systematic study on the influence of magnetic field imperfections in FFL MPI. Methods: In a simulation study, 14 different FFL scanner setups have been examined. Starting from an ideal scanner using perfect magnetic fields, defined imperfections have been introduced in a range of configurations (nonlinear gradient fields, inhomogeneous excitation fields, or inhomogeneous receive fields, or a combination thereof. In the first part of the study, the voltage induced in the receive channels parallel and perpendicular to the FFL translation have been studied for discrete FFL angles. In the second part, an imaging process has been simulated comparing different image reconstruction approaches. Results: The induced voltage signals demonstrate illustratively the effect of the magnetic field imperfections. In images reconstructed using a Radon-based approach, the magnetic field imperfections lead to pronounced artifacts, especially if a deconvolution using the point spread function is performed. In images reconstructed using a system function based approach, variations in local image quality become visible. Conclusion: For Radon-based image reconstruction in FFL MPI in the presence of inhomogeneous and nonlinear magnetic fields, artifact correction methods will have to be developed. In this regard, a first approach has recently been presented by

  11. Using Moessbauer spectroscopy as key technique in the investigation of nanosized magnetic particles for drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Morais, P. C., E-mail: pcmor@unb.br [Universidade de Brasilia, Nucleo de Fisica Aplicada, Instituto de Fisica (Brazil)

    2008-01-15

    This paper describes how cobalt ferrite nanoparticles, suspended as ionic or biocompatible magnetic fluids, can be used as a platform to built complex nanosized magnetic materials, more specifically magnetic drug delivery systems. In particular, the paper is addressed to the discussion of the use of the Moessbauer spectroscopy as an extremely useful technique in supporting the investigation of key aspects related to the properties of the hosted magnetic nanosized particle. Example of the use of the Moessbauer spectroscopy in accessing information regarding the nanoparticle modification due to the empirical process which provides long term chemical stability is included in the paper.

  12. Plasma transport in stochastic magnetic fields. I. General considerations and test particle transport

    Energy Technology Data Exchange (ETDEWEB)

    Krommes, J.A.; Kleva, R.G.; Oberman, C.

    1978-05-01

    A systematic theory is developed for the computation of electron transport in stochastic magnetic fields. Small scale magnetic perturbations arising, for example, from finite-..beta.. micro-instabilities are assumed to destroy the flux surfaces of a standard tokamak equilibrium. Because the magnetic lines then wander in a volume, electron radial flux is enhanced due to the rapid particle transport along as well as across the lines. By treating the magnetic lines as random variables, it is possible to develop a kinetic equation for the electron distribution function. This is solved approximately to yield the diffusion coefficient.

  13. A magnetic nano-particle ink for tunable microwave applications

    KAUST Repository

    Ghaffar, Farhan A.

    2016-12-19

    Inkjet printing or printing for realization of inexpensive and large area electronics has unearthed as an attractive fabrication technique. Though at present, mostly the metallic inks are printed on regular microwave substrates. In this paper, a fully printed multilayer fabrication process is demonstrated where the substrate is also realized through printing. A novel Fe2O3 based magnetic ink is used as a substrate while an in-house silver organo complex (SOC) ink is developed for metallic layers. Complete magnetostatic and microwave characterization of the ink is presented. At the end, a tunable patch antenna is shown as an application using the magnetic ink as the substrate. The antenna shows a tuning range of 12.5 % for a magnetic field strength of 3 kOe.

  14. Nonlinear interaction of charged particles with strong laser pulses in a magnetic undulator

    Directory of Open Access Journals (Sweden)

    H. K. Avetissian

    2010-08-01

    Full Text Available Laser acceleration due to the nonlinear-threshold phenomena of charged particle “reflection” and capture by slowed wave in a magnetic undulator is considered. The obtained numerical results prove the particle reflection and capture phenomena in the field of actual laser pulses with temporal and space profiles which lead to the particles acceleration. In contrast to the reflection regime where particle acceleration takes place already at the constant undulator step, in the capture regime it is necessary to increase adiabatically the undulator step along the laser pulse propagation direction by the certain self-consistent variation law corresponding to acceleration rate.

  15. Particle Acceleration in Collapsing Magnetic Traps with a Braking Plasma Jet

    CERN Document Server

    Borissov, Alexei; Threlfall, James

    2016-01-01

    Collapsing magnetic traps (CMTs) are one proposed mechanism for generating non-thermal particle populations in solar flares. CMTs occur if an initially stretched magnetic field structure relaxes rapidly into a lower-energy configuration, which is believed to happen as a by-product of magnetic reconnection. A similar mechanism for energising particles has also been found to operate in the Earth's magnetotail. One particular feature proposed to be of importance for particle acceleration in the magnetotail is that of a braking plasma jet, i.e. a localised region of strong flow encountering stronger magnetic field which causes the jet to slow down and stop. Such a feature has not been included in previously proposed analytical models of CMTs for solar flares. In this work we incorporate a braking plasma jet into a well studied CMT model for the first time. We present results of test particle calculations in this new CMT model. We observe and characterise new types of particle behaviour caused by the magnetic stru...

  16. Superparamagnetic particle dynamics and mixing in a rotating capillary tube with a stationary magnetic field.

    Science.gov (United States)

    Lee, Jun-Tae; Abid, Aamir; Cheung, Ka Ho; Sudheendra, L; Kennedy, Ian M

    2012-09-01

    The dynamics of superparamagnetic particles subject to competing magnetic and viscous drag forces have been examined with a uniform, stationary, external magnetic field. In this approach, competing drag and magnetic forces were created in a fluid suspension of superparamagnetic particles that was confined in a capillary tube; competing viscous drag and magnetic forces were established by rotating the tube. A critical Mason number was determined for conditions under which the rotation of the capillary prevents the formation of chains from individual particles. The statistics of chain length were investigated by image analysis while varying parameters such as the rotation speed and the viscosity of the liquid. The measurements showed that the rate of particle chain formation was decreased with increased viscosity and rotation speed ; the particle dynamics could be quantified by the same dimensionless Mason number that has been demonstrated for rotating magnetic fields. The potential for enhancement of mixing in a bioassay was assessed using a fast chemical reaction that was diffusion-limited. Reducing the Mason below the critical value, so that chains were formed in the fluid, gave rise to a modest improvement in the time to completion of the reaction.

  17. Heat-Affected Behavior of the Magnetic Properties of Iron Nano-Particles

    Institute of Scientific and Technical Information of China (English)

    柳刚; 吕楠; 秦伯雄; 范荣焕; 郭院波

    2004-01-01

    The high surface energy makes metal nano-particles reactive and easy to get oxidized or burned in the open air, which results in decreasing or entirely losing their functions and properties. In this paper, the mag netic property behavior of iron nano-particle, which is one kind of the typical magnetic nano-materials, has been investigated. The iron nano-particles were heated to different temperatures in an open-air stove. After that, they were firstly examined by TEM to observe the changes of their outline of shapes and then measured by VSM to trace the changes of their magnetic properties. The test results show that iron nano-particles can keep their magnetic property with saturation magnetic induction intensity B, around 136-161 emu/g, remanent magnetic induction intensity Br around 14.8-17.4 emu/g and coercive force Hc around 290-302 Oe when the temperature goes up to 523 K. The explanation to such outstanding oxidization-proof ability has been given that there exists a single crystal and lattice-shared Gamma-Fe2O3 shell covering the pure iron core, which prevents the spherical iron nano-particles from further oxidization.

  18. Brownian particle-kinetics in a superparamagnetic ferrofluid subjected to static magnetic-field

    Science.gov (United States)

    Trisnanto, Suko Bagus; Kitamoto, Yoshitaka

    2017-01-01

    The stochastic Brownian particle-kinetics in a superparamagnetic ferrofluid at room temperature is of significance in nullifying total magnetization vectors of the suspended particles. Correspondingly, the apparent magnetization response observed under static magnetic field shows no hysteresis loop, but being linear at a given finite field-difference. Owing to this superparamagnetism, we propose a differential magnetometry to analyze the static field-induced particle-kinetics and further to identify the effective field-strength in reorienting particle-moments toward the applied field direction. A polydispersive ferrofluid containing iron-oxide nanoparticles, in practice, is subjected to a very-low oscillatory-field, immediately after applying the static-field. For a given frequency, we confirm a decreasing ac susceptibility as dc field-strength increases, which suggests a statistically less fluctuating magnetization-vectors. Via numerical integration of ac susceptibility recorded, we furthermore estimate the nonlinear quasi-static magnetization at various measurement frequencies. The resulting nonlinearity is attributable to the contributing relaxation dynamics of the particles. More importantly, the difference between dc and ac susceptibilities is found to be field-strength and frequency-dependent. Its value is further maximized at an effective field-strength, from which we identified the coexisting energy-barriers.

  19. Modeling Superparamagnetic Particles in Blood Flow for Applications in Magnetic Drug Targeting

    Directory of Open Access Journals (Sweden)

    Iris Rukshin

    2017-06-01

    Full Text Available Magnetic drug targeting is a technique that involves the binding of medicine to magnetizable particles to allow for more specific transport to the target location. This has recently come to light as a method of drug delivery that reduces the disadvantages of conventional, systemic treatments. This study developed a mathematical model for tracking individual superparamagnetic nanoparticles in blood flow in the presence of an externally applied magnetic field. The model considers the magnetic attraction between the particles and the external magnet, influence of power law flow, diffusive interaction between the particles and blood, and random collisions with red blood cells. A stochastic system of differential equations is presented and solved numerically to simulate the paths taken by particles in a blood vessel. This study specifically focused on localized cancer treatment, in which a surface tumor is accessed through smaller blood vessels, which are more conducive to this delivery method due to slower flow velocities and smaller diameters. The probability of the particles reaching the tumor location is found to be directly dependent on ambient factors; thus, diffusion through Brownian motion and red blood cell collisions, different magnetic field and force models, blood viscosities, and release points are considered.

  20. Pulsed magnetic field from video display terminals enhances teratogenic effects of cytosine arabinoside in mice

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, H.; Wu, R.Y.; Shao, B.J.; Fu, Y.D.; Yao, G.D.; Lu, D.J. [Zhejiang Medical Univ. (China)

    1995-05-01

    Eighty-nine Swiss Webster mice were randomly divided into four groups: a control group, a pulsed magnetic field (PMF) group, a cytosine arabinoside (ara-C, a teratogen) group, and a combined PMF + ara-C group. Mice in the PMF and PMF + ara-C groups were irradiated with a PMF (a sawtooth waveform with 52 {mu}s rise time, 12{mu}s decay time, and 15.6 kHz frequency) at a peak magnetic flux density of 40 {mu}T for 4 hours daily on days 6-17 of gestation. The mice in the ara-C and the PMF + ara-C groups were injected intraperitoneally on day 9 of gestation with 10 mg/kg of ara-C. The incidence of resorption and dead fetuses was not affected by PMF but was increased by ara-C injection. The malformation incidence of cleft palate (CP) and/or cleft lip (CL) was significantly higher in all three of the treated groups than in the control group (P < 0.05). If, however, statistical analyses had been done on litters rather than on individual fetuses, they would show that the incidence of CP and/or CL in the PMF group is not significantly greater than that in the control group. A significantly higher incidence of CP and/or CL was found in the PMF + ara-C group (49%) than the ara-C alone group (26.1%). These data suggest that PMF might enhance the development of ara-C-induced CP and/or CL. The incidence of minor variations in skeletal development, including reduction of skeletal calcification and loss of skeleton, was not statistically significant in the PMF group. However, it was higher in the two ara-C-treated groups, and there was no significant difference between the ara-C alone group and the ara-C + PMF group. From these results it is concluded that the very weak embryotoxic effects of PMF exposure may be revealed and enhanced in combination with a teratogenic agent.

  1. Particle Yields in Heavy Ion Collisions and the Influence of Strong Magnetic Fields

    Directory of Open Access Journals (Sweden)

    M. G. de Paoli

    2014-01-01

    Full Text Available It is expected that the magnetic fields in heavy ion collisions are very high. In this work, we investigate the effects of a strong magnetic field on particle ratios within a thermal model of particle production. We model matter as a free gas of baryons and mesons under the influence of an external magnetic field varying from zero to 30mπ2 through an  χ2 fitting to some data sets of the STAR experiment. For this purpose, we use the Dirac, Rarita-Schwinger, Klein-Gordon, and Proca equations subject to magnetic fields in order to obtain the energy expressions and the degeneracy for spin 1/2, spin 3/2, spin 0, and spin 1 particles, respectively. Our results show that, if the magnetic field can be considered as slowly varying and leaves its signature on the particle yields, a field of the order of 6mπ2 produces an improved fitting to the experimental data as compared to the calculations without magnetic field.

  2. Investigation on Tc tuned nano particles of magnetic oxides for hyperthermia applications.

    Science.gov (United States)

    Giri, Jyotsnendu; Ray, Amlan; Dasgupta, S; Datta, D; Bahadur, D

    2003-01-01

    Superparamagnetic as well as fine ferrimagnetic particles such as Fe3O4, have been extensively used in magnetic field induced localized hyperthermia for the treatment of cancer. The magnetic materials with Curie temperature (Tc) between 42 and 50 degrees C, with sufficient biocompatibility are the best candidates for effective treatment such that during therapy it acts as in vivo temperature control switch and thus over heating could be avoided. Ultrafine particles of substituted ferrite Co(1-a)Zn(a)Fe2O4 and substituted yttrium-iron garnet Y3Fe(5-x)Al(x)O12 have been prepared through microwave refluxing and citrate-gel route respectively. Single-phase compounds were obtained with particle size below 100 nm. In order to make these magnetic nano particles biocompatible, we have attempted to coat these above said composition by alumina. The coating of alumina was done by hydrolysis method. The coating of hydrous aluminium oxide has been done over the magnetic particles by aging the preformed solid particles in the solution of aluminium sulfate and formamide at elevated temperatures. In vitro study is carried out to verify the innocuousness of coated materials towards cells. In vitro biocompatibility study has been carried out by cell culture method for a period of three days using human WBC cell lines. Study of cell counts and SEM images indicates the cells viability/growth. The in vitro experiments show that the coated materials are biocompatible.

  3. Measurement of the adhesion force between particles for high gradient magnetic separation of pneumatic conveyed powder products

    Energy Technology Data Exchange (ETDEWEB)

    Senkawa, K., E-mail: senkawa@qb.see.eng.osaka-u.ac.jp [Osaka University, A1 Bldg, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Nakai, Y.; Mishima, F.; Akiyama, Y.; Nishijima, S. [Osaka University, A1 Bldg, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2011-11-15

    In the industrial plants such as foods, medicines or industrial materials, there are big amount of issues on contamination by metallic wear debris originated from pipes of manufacturing lines. In this study, we developed a high gradient magnetic separation system (HGMS) under the dry process by using superconducting magnet to remove the ferromagnetic particles. One of the major problems of dry HGMS systems is, however, the blockage of magnetic filter caused by particle coagulation or deposition. In order to actualize the magnetic separation without blockage, we introduced pneumatic conveyance system as a new method to feed the powder. It is important to increase the drag force acting on the sufficiently dispersed particles, which require strong magnetic fields. To generate the strong magnetic fields, HGMS technique was examined which consists of a magnetic filter and a superconducting solenoid magnet. As a result of the magnetic separation experiment, it was shown that the separation efficiency changes due to the difference of the cohesive property of the particles. On the basis of the result, the adhesion force which acts between the ferromagnetic particles and the medium particles used for the magnetic separation was measured by Atomic Force Microscope (AFM), and cohesion of particles was studied from the aspect of interparticle interaction. We assessed a suitable flow velocity for magnetic separation according to the cohesive property of each particle based on the result.

  4. Java-based framework for processing and displaying short-echo-time magnetic resonance spectroscopy signals.

    Science.gov (United States)

    De Neuter, B; Luts, J; Vanhamme, L; Lemmerling, P; Van Huffel, S

    2007-02-01

    Magnetic resonance spectroscopy (MRS) can be used to determine in a non-invasive way the concentrations of certain chemical substances, also called metabolites. The spectra of MRS signals contain peaks that correspond to the metabolites of interest. Short-echo-time signals are characterized by heavily overlapping metabolite peaks and require sophisticated processing methods. To be useful in a clinical environment tools are needed that can process those signals in an accurate and fast way. Therefore, we developed novel processing methods and we designed a freely available and open-source framework (http://www.esat.kuleuven.ac.be/sista/members/biomed) in which the processing methods can be integrated. The framework has a set of abstract classes, called hot spots, and its goal is to provide a general structure and determine the control flow of the program. It provides building blocks or components in order to help developers with integrating their methods in the framework via a plug-in system. The framework is designed with the unified modeling language (UML) and implemented in Java. When a developer implements the framework he gets an application that acts like a simple and user-friendly graphical user interface (GUI) for processing MRS data. This article describes in detail the structure and implementation of the framework and the integration of our processing methods in it.

  5. Aggregation dynamics and magnetic properties of magnetic micrometer-sized particles dispersed in a fluid under the action of rotating magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Llera, María [Instituto de Ciencias, Universidad Nacional de General Sarmiento, Buenos Aires (Argentina); Codnia, Jorge [Instituto de Ciencias, Universidad Nacional de General Sarmiento, Buenos Aires (Argentina); Centro de Investigaciones en Láseres y Aplicaciones, CITEDEF-CONICET, Buenos Aires (Argentina); Jorge, Guillermo A., E-mail: gjorge@ungs.edu.ar [Instituto de Ciencias, Universidad Nacional de General Sarmiento, Buenos Aires (Argentina)

    2015-06-15

    We present a dynamic study of soft magnetic, commercial Fe and Ni micrometer-sized particles dispersed in oleic acid and subjected to a variable (rotating) magnetic field in the horizontal plane. A very complex structure is formed after the particles decant towards the bottom liquid–solid interface and the magnetic field is applied for several minutes. The dynamics of structure formation was studied by means of the registration and analysis of microscopic video images, through a Matlab image analysis script. Several parameters, such as the number of clusters, the perimeter-based fractal dimension and circularity, were calculated as a function of time. The time evolution of the number of clusters was found to follow a power-law behavior, with an exponent consistent with that found in other studies for magnetic systems, whereas the typical formation time depends on the particle diameter and field configuration. Complementarily, the magnetic properties of the formed structure were studied, reproducing the experiment with liquid paraffin as the containing fluid, and then letting it solidify. The sample obtained was studied by vibrating sample magnetometry. The magnetization curves show that the material obtained is a planar magnetically anisotropic material, which could eventually be used as an anisotropic magnetic sensor or actuator. - Highlights: • Dynamic study of Fe and Ni particles in oleic acid under rotating fields. • A very complex system of interconnected clusters was observed. • Larger particles had a smaller aggregation time. • A power law behavior of the number of clusters vs. time. • A Fe-paraffin sample with planar anisotropy characterized.

  6. Magnetic dynamics of fine particles studied by inelastic neutron scattering

    CERN Document Server

    Hansen, M F; Moerup, S; Lefmann, K; Clausen, K N; Lindgaard, P A

    2000-01-01

    We give an introduction to inelastic neutron scattering and the dynamic scattering function for magnetic nanoparticles. Differences between ferromagnetic and antiferromagnetic nanoparticles are discussed and we give a review of recent results on ferromagnetic Fe nanoparticles and canted antiferromagnetic alpha-Fe sub 2 O sub 3 nanoparticles.

  7. Edge effect in charged-particle analyzing magnets

    NARCIS (Netherlands)

    Braams, C.M.

    1964-01-01

    The manner in which local saturation of pole pieces with sharp edges affects the fall-off of the magnetic induction in the fringing-field region is discussed and measured. Local saturation appears to set in at a field strength well below that at which over-all saturation of the pole pieces becomes n

  8. Edge effect in charged-particle analyzing magnets

    NARCIS (Netherlands)

    Braams, C.M.

    The manner in which local saturation of pole pieces with sharp edges affects the fall-off of the magnetic induction in the fringing-field region is discussed and measured. Local saturation appears to set in at a field strength well below that at which over-all saturation of the pole pieces becomes

  9. Application of AI techniques to a voice-actuated computer system for reconstructing and displaying magnetic resonance imaging data

    Science.gov (United States)

    Sherley, Patrick L.; Pujol, Alfonso, Jr.; Meadow, John S.

    1990-07-01

    To provide a means of rendering complex computer architectures languages and input/output modalities transparent to experienced and inexperienced users research is being conducted to develop a voice driven/voice response computer graphics imaging system. The system will be used for reconstructing and displaying computed tomography and magnetic resonance imaging scan data. In conjunction with this study an artificial intelligence (Al) control strategy was developed to interface the voice components and support software to the computer graphics functions implemented on the Sun Microsystems 4/280 color graphics workstation. Based on generated text and converted renditions of verbal utterances by the user the Al control strategy determines the user''s intent and develops and validates a plan. The program type and parameters within the plan are used as input to the graphics system for reconstructing and displaying medical image data corresponding to that perceived intent. If the plan is not valid the control strategy queries the user for additional information. The control strategy operates in a conversation mode and vocally provides system status reports. A detailed examination of the various AT techniques is presented with major emphasis being placed on their specific roles within the total control strategy structure. 1.

  10. High performance current controller for particle accelerator magnets supply

    DEFF Research Database (Denmark)

    Maheshwari, Ram Krishan; Bidoggia, Benoit; Munk-Nielsen, Stig;

    2013-01-01

    The electromagnets in modern particle accelerators require high performance power supply whose output is required to track the current reference with a very high accuracy (down to 50 ppm). This demands very high bandwidth controller design. A converter based on buck converter topology is used in ...

  11. Big magnet glitch at world's top particle accelerator

    CERN Multimedia

    Weiss, Giselle

    2007-01-01

    "Officials at CERN, near Geneva, believe they have found a solution to the latest hitch in the construction of the Large Hadron Collider (LHC), a state-of-the-art particle accelerator that straddles the Franco-Swiss border." (1 page)

  12. A complete model of solar energetic particle propagation in 3-dimensional interplanetary magnetic field

    Science.gov (United States)

    Zhang, Ming; Rassoul, Hamid; Qin, Gang

    We present a model calculation of solar energetic particle propagation in a realistic 3-d Interplanetary magnetic field. The model includes essentially all the particle transport mechanisms: streaming along magnetic fields, convection with the solar wind, pitch-angle diffusion, magnetic focusing, cross-field diffusion, and adiabatic cooling with pitch-angle dependence. We solve a Fokker-Planck transport equation with simulation of stochastic processes in a fixed reference frame, in which an observer on a spacecraft is roughly stationary. For simplicity, as the first model calculation of this sort, we focus on high-energy E > 10 MeV solar energetic particles that are accelerated near the Sun and then released into interplanetary space. The source of solar energetic particles can be either solar flares or coronal mass ejections, both having limited coverage of latitude and longitude on the solar surface. We compute the particle flux and anisotropy profiles for various observation locations in interplanetary space up to 5 AU from the ecliptic to the poles. Our model calculation results can explain why we often see solar energetic particles reach an almost uniform reservoir in the inner heliosphere a few days after onset of a solar energetic particle event and then the intensities of particles in a broad range of particle energies decay uniformly everywhere. This phenomenon can happen without a need of particle diffusion barrier in the outer heliosphere. We will discuss what mechanism is behind the formation of such a reservoir and what role the cross-field diffusion plays in the transport of solar energetic particles.

  13. Particle transport in magnetized media around black holes and associated radiation

    CERN Document Server

    Vieyro, Florencia L

    2012-01-01

    Galactic black hole coronae are composed of a hot, magnetized plasma. The spectral energy distribution produced in this component of X-ray binaries can be strongly affected by different interactions between locally injected relativistic particles and the matter, radiation and magnetic fields in the source. We study the non-thermal processes driven by the injection of relativistic particles into a strongly magnetized corona around an accreting black hole. We compute in a self-consistent way the effects of relativistic bremsstrahlung, inverse Compton scattering, synchrotron radiation, and the pair-production/annihilation of leptons, as well as hadronic interactions. Our goal is to determine the non-thermal broadband radiative output of the corona. The set of coupled kinetic equations for electrons, positrons, protons, and photons are solved and the resulting particle distributions are computed self-consistently. The spectral energy distributions of transient events in X-ray binaries are calculated, as well as t...

  14. Magnetic Particles Coupled to Disposable Screen Printed Transducers for Electrochemical Biosensing

    Directory of Open Access Journals (Sweden)

    Paloma Yáñez-Sedeño

    2016-09-01

    Full Text Available Ultrasensitive biosensing is currently a growing demand that has led to the development of numerous strategies for signal amplification. In this context, the unique properties of magnetic particles; both of nano- and micro-size dimensions; have proved to be promising materials to be coupled with disposable electrodes for the design of cost-effective electrochemical affinity biosensing platforms. This review addresses, through discussion of selected examples, the way that nano- and micro-magnetic particles (MNPs and MMPs; respectively have contributed significantly to the development of electrochemical affinity biosensors, including immuno-, DNA, aptamer and other affinity modes. Different aspects such as type of magnetic particles, assay formats, detection techniques, sensitivity, applicability and other relevant characteristics are discussed. Research opportunities and future development trends in this field are also considered.

  15. Magnetic Particles Coupled to Disposable Screen Printed Transducers for Electrochemical Biosensing

    Science.gov (United States)

    Yáñez-Sedeño, Paloma; Campuzano, Susana; Pingarrón, José M.

    2016-01-01

    Ultrasensitive biosensing is currently a growing demand that has led to the development of numerous strategies for signal amplification. In this context, the unique properties of magnetic particles; both of nano- and micro-size dimensions; have proved to be promising materials to be coupled with disposable electrodes for the design of cost-effective electrochemical affinity biosensing platforms. This review addresses, through discussion of selected examples, the way that nano- and micro-magnetic particles (MNPs and MMPs; respectively) have contributed significantly to the development of electrochemical affinity biosensors, including immuno-, DNA, aptamer and other affinity modes. Different aspects such as type of magnetic particles, assay formats, detection techniques, sensitivity, applicability and other relevant characteristics are discussed. Research opportunities and future development trends in this field are also considered. PMID:27681733

  16. Design and characterization of a device to quantify the magnetic drug targeting efficiency of magnetic nanoparticles in a tube flow phantom by magnetic particle spectroscopy

    Science.gov (United States)

    Radon, Patricia; Löwa, Norbert; Gutkelch, Dirk; Wiekhorst, Frank

    2017-04-01

    The aim of magnetic drug targeting (MDT) is to transfer a therapeutic drug coupled to magnetic nanoparticles (MNP) to desired disease locations (e.g. tumor region) with the help of magnetic field gradients. To transfer the MDT approach into clinical practice a number of important issues remain to be solved. We developed and characterized an in-vitro flow phantom to provide a defined and reproducible MDT environment. The tube system of the flow phantom is directed through the detection coil of a magnetic particle spectroscopy (MPS) device to determine the targeting efficiency. MPS offers an excellent temporal resolution of seconds and an outstanding specific sensitivity of some nanograms of iron. In the flow phantom different MNP types, magnet geometries and tube materials can be employed to vary physical parameters like diameter, flow rate, magnetic targeting gradient, and MNP properties.

  17. Emerging boom in nano magnetic particle incorporated high-Tc superconducting materials and technologies - A South African perspective

    CSIR Research Space (South Africa)

    Srinivasu, VV

    2009-01-01

    Full Text Available With a strategy to establish and embrace the emerging nano particle incorporated superconductivity technology (based on the HTS materials and nano magnetic particles) in South Africa, the author has initiated the following research activity in South...

  18. Nuclear Technology. Course 32: Nondestructive Examination (NDE) II. Module 32-3, Fundamentals of Magnetic Particle Testing.

    Science.gov (United States)

    Groseclose, Richard

    This third in a series of six modules for a course titled Nondestructive Examination (NDE) Techniques II explains the principles of magnets and magnetic fields and how they are applied in magnetic particle testing, describes the theory and methods of magnetizing test specimens, describes the test equipment used, discusses the principles and…

  19. Case Studies on Superconducting Magnets for Particle Accelerators

    CERN Document Server

    Ferracin, P

    2014-01-01

    During the CERN Accelerator School 'Superconductivity for accelerators', the students were divided into 18 groups, and 6 different exercises (case studies), involving the design and analysis of superconducting magnets and RF cavities, were assigned. The problems covered a broad spectrum of topics, from properties of superconducting materials to operation conditions and general dimensions of components. The work carried out by the students turned out to be an extremely useful opportunity to review the material explained during the lectures, to become familiar with the orders of magnitude of the key parameters, and to understand and compare different design options. We provide in this paper a summary of the activities related to the case studies on superconducting magnets and present the main outcomes.

  20. Optical and magnetic characterization of theranostic magnetite particles (Conference Presentation)

    Science.gov (United States)

    Cialla-May, Dana; Patze, Sophie; Mueller, Robert; Weber, Karina; Popp, Jürgen

    2017-02-01

    Magnetic nanoparticles (MNPs) have a major role as contrast agent in diagnostic imaging and therapeutic monitoring. In order to research on MNP exposition, degradation and elimination of those nano composites as well as the consequences of the MNP exposition in relation with social economic relevant diseases (cancer, infectious diseases), the comprehensive characterization of magnetic and structural properties is of high importance. Within this contribution, the magnetic characterization of theranostic relevant MNPs is introduced. Applying a vibrating sample magnetometer (VSM), it is found, that the nanocomposites show superparamagnetic behavior and the recorded data confirm iron oxide cores (magnetite/maghemite). Employing Raman spectroscopy, the typical fingerprint information of magnetite is detected. By increasing the laser power, the transition to maghemite and hematite due to the oxidation of the magnetic core is illustrated. Moreover, IR spectroscopy is applied to characterize the coating material e.g. starch or other biocompatible polymers. To determine the stability of MNPs as well as the MNP's elimination under physiological conditions, different buffer systems were tested i.e. simulated body fluid (SBF) and artificial lysosomal fluid (ALF). The investigated MNPs are stable in SBF; thus, the stability in blood after injection of the contrast agent is guaranteed. Finally, the storage in ALF leads to a complete decomposition of the MNPs, which reflects the conditions in lysosomes and guarantee for a fast MNP elimination. Acknowledgement: We thank the Federal Ministry of Education and Research (BMBF), Germany as well as the Project Management Jülich (PTJ), Germany for funding the research project NanoBEL (03XP0003F).

  1. Phenomena of charged particles transport in variable magnetic fields

    CERN Document Server

    Savane, S Y; Faza-Barry, M; Vladmir, L

    2002-01-01

    This present work is dedicated to the study of the dynamical phenomena for the transport of ions in the presence of variable magnetic fields in front of the Jupiter wave shock. We obtain the spectrum of the accelerated ions and we study the conditions of acceleration by solving the transport equation in the planetocentric system. We discuss the theoretical results obtained and make a comparison with the experimental parameters in the region of acceleration behind the Jupiter wave shock.

  2. Polystyrene-Core-Silica-Shell Hybrid Particles Containing Gold and Magnetic Nanoparticles.

    Science.gov (United States)

    Tian, Jia; Vana, Philipp

    2016-02-18

    Polystyrene-core-silica-shell hybrid particles were synthesized by combining the self-assembly of nanoparticles and the polymer with a silica coating strategy. The core-shell hybrid particles are composed of gold-nanoparticle-decorated polystyrene (PS-AuNP) colloids as the core and silica particles as the shell. PS-AuNP colloids were generated by the self-assembly of the PS-grafted AuNPs. The silica coating improved the thermal stability and dispersibility of the AuNPs. By removing the "free" PS of the core, hollow particles with a hydrophobic cage having a AuNP corona and an inert silica shell were obtained. Also, Fe3O4 nanoparticles were encapsulated in the core, which resulted in magnetic core-shell hybrid particles by the same strategy. These particles have potential applications in biomolecular separation and high-temperature catalysis and as nanoreactors.

  3. Moessbauer study of Martensitic transformation and collective magnetic excitations in Fe9Ni1 fine particles

    Institute of Scientific and Technical Information of China (English)

    H.M.Widatallah; 黄润生; 等

    1996-01-01

    The austenite to martensity ransformation in fine Fe90Ni.10 particles prepared by evaporation is studied by Moessbauer technique.Unlike bulk Fe.9Ni.1 which is entirely transformed to martensite.these particles show a remarkable austenite stability upon cooling upto liquid nitrogen temperature.This stability is associated with the oxide surface layer formed on the particles and also with their small size.A hyperfine field approach is employed to analyze the martensitic transformation in the particles.It is also shown that,in contrast with large particles ,the temperature variation of the Moessbauer average hyperfine field of the fine particles can be satisfactorily explained in terms of the collective magnetic excitations model.

  4. ON THE DISTRIBUTION OF PARTICLE ACCELERATION SITES IN PLASMOID-DOMINATED RELATIVISTIC MAGNETIC RECONNECTION

    Energy Technology Data Exchange (ETDEWEB)

    Nalewajko, Krzysztof [Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, Stanford University, 2575 Sand Hill Road M/S 29, Menlo Park, CA 94025 (United States); Uzdensky, Dmitri A.; Werner, Gregory R. [Center for Integrated Plasma Studies, Physics Department, University of Colorado, UCB 390, Boulder, CO 80309-0390 (United States); Cerutti, Benoit [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Begelman, Mitchell C., E-mail: knalew@stanford.edu [JILA, University of Colorado and National Institute of Standards and Technology, 440 UCB, Boulder, CO 80309 (United States)

    2015-12-20

    We investigate the distribution of particle acceleration sites, independently of the actual acceleration mechanism, during plasmoid-dominated, relativistic collisionless magnetic reconnection by analyzing the results of a particle-in-cell numerical simulation. The simulation is initiated with Harris-type current layers in pair plasma with no guide magnetic field, negligible radiative losses, no initial perturbation, and using periodic boundary conditions. We find that the plasmoids develop a robust internal structure, with colder dense cores and hotter outer shells, that is recovered after each plasmoid merger on a dynamical timescale. We use spacetime diagrams of the reconnection layers to probe the evolution of plasmoids, and in this context we investigate the individual particle histories for a representative sample of energetic electrons. We distinguish three classes of particle acceleration sites associated with (1) magnetic X-points, (2) regions between merging plasmoids, and (3) the trailing edges of accelerating plasmoids. We evaluate the contribution of each class of acceleration sites to the final energy distribution of energetic electrons: magnetic X-points dominate at moderate energies, and the regions between merging plasmoids dominate at higher energies. We also identify the dominant acceleration scenarios, in order of decreasing importance: (1) single acceleration between merging plasmoids, (2) single acceleration at a magnetic X-point, and (3) acceleration at a magnetic X-point followed by acceleration in a plasmoid. Particle acceleration is absent only in the vicinity of stationary plasmoids. The effect of magnetic mirrors due to plasmoid contraction does not appear to be significant in relativistic reconnection.

  5. On-chip determination of C-reactive protein using magnetic particles in continuous flow.

    Science.gov (United States)

    Phurimsak, Chayakom; Tarn, Mark D; Peyman, Sally A; Greenman, John; Pamme, Nicole

    2014-11-01

    We demonstrate the application of a multilaminar flow platform, in which functionalized magnetic particles are deflected through alternating laminar flow streams of reagents and washing solutions via an external magnet, for the rapid detection of the inflammatory biomarker, C-reactive protein (CRP). The two-step sandwich immunoassay was accomplished in less than 60 s, a vast improvement on the 80-300 min time frame required for enzyme-linked immunosorbent assays (ELISA) and the 50 min necessary for off-chip magnetic particle-based assays. The combination of continuous flow and a stationary magnet enables a degree of autonomy in the system, while a detection limit of 0.87 μg mL(-1) makes it suitable for the determination of CRP concentrations in clinical diagnostics. Its applicability was further proven by assaying real human serum samples and comparing those results to values obtained using standard ELISA tests.

  6. Micromagnetic simulation of vortex-antivortex magnetization in permalloy nano particle

    Science.gov (United States)

    Purnama, B.; Muhammady, S.; Suharyana

    2017-02-01

    A process of vortex-antivortex magnetization reversal in a Permalloy nano particle with uniform polarity of magnetization has been investigated numerically. Micromagnetic simulation is performed using the Landau–Lifshitz–Gilbert equation. A short field pulse is applied in a film plane anti parallel to magnetization direction. Sequences of simulation of reversals mechanism are evaluated for thickness of nano particle. As the results in the case of thickness of 20 nm thin layer, magnetization reversal realizes through a creation-annihilation of Neel-Bloch wall pair. Contrarily, reversal mechanism via a creation-annihilation process of vortex-antivortex pair occurs for thickness of 60 nm thin layer. By analyzing barrier energy of the sample, we find that a maximum barrier energy reaches a threshold value (e.g., ∼ 2.6×106 erg/cm3 for Permalloy in this simulation).

  7. Combined Néel and Brown rotational Langevin dynamics in magnetic particle imaging, sensing, and therapy

    Energy Technology Data Exchange (ETDEWEB)

    Reeves, Daniel B., E-mail: dbr@Dartmouth.edu [Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States); Weaver, John B. [Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States); Department of Radiology, Geisel School of Medicine, Hanover, New Hampshire 03755 (United States)

    2015-11-30

    Magnetic nanoparticles have been studied intensely because of their possible uses in biomedical applications. Biosensing using the rotational freedom of particles has been used to detect biomarkers for cancer, hyperthermia therapy has been used to treat tumors, and magnetic particle imaging is a promising new imaging modality that can spatially resolve the concentration of nanoparticles. There are two mechanisms by which the magnetization of a nanoparticle can rotate, a fact that poses a challenge for applications that rely on precisely one mechanism. The challenge is exacerbated by the high sensitivity of the dominant mechanism to applied fields. Here, we demonstrate stochastic Langevin equation simulations for the combined rotation in magnetic nanoparticles exposed to oscillating applied fields typical to these applications to both highlight the existing relevant theory and quantify which mechanism should occur in various parameter ranges.

  8. Particle Energization During Magnetic Storms with Steady Magnetospheric Convection

    Science.gov (United States)

    Kissinger, J.; Kepko, L.; Baker, D. N.; Kanekal, S. G.; Li, W.; McPherron, R. L.; Angelopoulos, V.

    2013-12-01

    Relativistic electrons pose a space weather hazard to satellites in the radiation belts. Although about half of all geomagnetic storms result in relativistic electron flux enhancements, other storms decrease relativistic electron flux, even under similar solar wind drivers. Radiation belt fluxes depend on a complex balance between transport, loss, and acceleration. A critically important aspect of radiation belt enhancements is the role of the 'seed' population--plasma sheet particles heated and transported Earthward by magnetotail processes--which can become accelerated by wave-particle interactions with chorus waves. While the effect of substorms on seed electron injections has received considerable focus, in this study we explore how quasi-steady convection during steady magnetospheric convection (SMC) events affects the transport and energization of electrons. SMC events are long-duration intervals of enhanced convection without any substorm expansions, and are an important mechanism in coupling magnetotail plasma populations to the inner magnetosphere. We detail the behavior of the seed electron population for stormtime SMC events using the Van Allen Probes in the outer radiation belt and THEMIS in the plasma sheet and inner magnetosphere. Together, the two missions provide the ability to track particle transport and energization from the plasma sheet into the radiation belts. We present SMC events with Van Allen Probes/THEMIS conjunctions and compare plasma sheet fast flows/enhanced transport to radiation belt seed electron enhancements. Finally we utilize statistical analyses to quantify the relative importance of SMC events on radiation belt electron acceleration in comparison to isolated substorms.

  9. Affinity selection of Nipah and Hendra virus-related vaccine candidates from a complex random peptide library displayed on bacteriophage virus-like particles

    Energy Technology Data Exchange (ETDEWEB)

    Peabody, David S.; Chackerian, Bryce; Ashley, Carlee; Carnes, Eric; Negrete, Oscar

    2017-01-24

    The invention relates to virus-like particles of bacteriophage MS2 (MS2 VLPs) displaying peptide epitopes or peptide mimics of epitopes of Nipah Virus envelope glycoprotein that elicit an immune response against Nipah Virus upon vaccination of humans or animals. Affinity selection on Nipah Virus-neutralizing monoclonal antibodies using random sequence peptide libraries on MS2 VLPs selected peptides with sequence similarity to peptide sequences found within the envelope glycoprotein of Nipah itself, thus identifying the epitopes the antibodies recognize. The selected peptide sequences themselves are not necessarily identical in all respects to a sequence within Nipah Virus glycoprotein, and therefore may be referred to as epitope mimics VLPs displaying these epitope mimics can serve as vaccine. On the other hand, display of the corresponding wild-type sequence derived from Nipah Virus and corresponding to the epitope mapped by affinity selection, may also be used as a vaccine.

  10. Magnetic properties, microstructure and mineralogical phases of technogenic magnetic particles (TMPs) in urban soils: Their source identification and environmental implications.

    Science.gov (United States)

    Lu, Shenggao; Yu, Xiuling; Chen, Yuyin

    2016-02-01

    Magnetic measurement is an effective method to determine spatial distribution and the degree of heavy metal pollution and to identify various anthropogenic sources of heavy metals. The objectives of this investigation are to characterize the magnetic properties, microstructure and mineralogical phases of technogenic magnetic particles (TMPs) in urban soils and to discuss their potential environmental implications. The TMPs are separated from the urban topsoils of Luoyang city, China. The magnetic properties, morphology, and mineral phase of TMPs are studied using mineral magnetic measurement, scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM/EDS), X-ray diffraction, and synchrotron-radiation-based microprobe. The content of TMPs in urban topsoils ranges from 0.05 to 1.95% (on average 0.32%). The magnetic susceptibility of TMPs ranges from 4559×10(-8) to 23,661×10(-8) m(3) kg(-1) (on average 13,637×10(-8) m(3) kg(-1)). Thermomagnetic and bulk X-ray diffraction analyses indicate that main magnetic minerals of TMPs are magnetite (Fe3O4) and hematite (α-Fe2O3). The morphology of TMPs observed by SEM includes three shape types: spherule, irregular-shaped, and aggregate particles. The size of spherical TMPs ranges from 30 to about 200 μm, with the largest percentage of 30-50 μm. Synchrotron-radiation-based microprobe (μ-XRF and μ-XRD) indicates that TMPs are enriched with heavy metals Pb, Cd, Zn, Cu, and Cr, which are incorporated into lattice or adsorbed on the surface of magnetite/hematite. The content of TMPs significantly relates with the Tomlinson Pollution Load Index (PLI) (R(2)=0.467), suggesting that it can be used as proxy indicator of degree of heavy metal contamination in urban soils. The magnetic properties, microstructure and mineralogical phases of TMPs can serve as the identification of pollution sources in urban soils.

  11. SLAC T-510: Radio emission from particle cascades in the presence of a magnetic field

    Science.gov (United States)

    Mulrey, Katharine

    2017-03-01

    Cosmic ray induced particle cascades radiate in radio frequencies in the Earth's atmosphere. Geomagnetic and Askaryan emission provide an effective way to detect ultra-high energy cosmic rays. The SLAC T-510 experiment was the first to measure magnetically induced radiation from particle cascades in a controlled laboratory setting. An electron beam incident upon a dense dielectric target produced a particle cascade in the presence of a variable magnetic field. Antennas covering a band of 30-3000 MHz sampled RF emission in vertical and horizontal polarizations. Results from T-510 are compared to particle-level RF-emission simulations which are critical for reconstructing the energy and composition of detected ultra-high energy cosmic ray air showers. We discuss the experimental set up, the data processing, the systematic errors and the main results of the experiment, which we found in a good agreement with the simulations.

  12. Chaotic Dynamics of Test Particle in the Gravitational Field with Magnetic Dipoles

    Institute of Scientific and Technical Information of China (English)

    CHEN Ju-Hua; WANG Yong-Jiu

    2003-01-01

    We investigate the dynamics of the test particle in the gravitational field with magnetic dipoles in thispaper. At first we study the gravitational potential by numerical simulations. We find, for appropriate parameters, thatthere are two different cases in the potential curve, one of which is the one-well case with a stable critical point, and theother is the three-well case with three stable critical points and two unstable ones. As a consequence, the chaotic motionwill rise. By performing the evolution of the orbits of the test particle in the phase space, we find that the orbits of thetest particle randomly oscillate without any periods, even sensitively depending on the initial conditions and parameters.chaotic motion of the test particle in the field with magnetic dipoles becomes even obvious as the value of the magneticdipoles increases.

  13. Inductively Coupled Plasma: Fundamental Particle Investigations with Laser Ablation and Applications in Magnetic Sector Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Saetveit, Nathan Joe [Iowa State Univ., Ames, IA (United States)

    2008-01-01

    Particle size effects and elemental fractionation in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) are investigated with nanosecond and femtosecond laser ablation, differential mobility analysis, and magnetic sector ICP-MS. Laser pulse width was found to have a significant influence on the LA particle size distribution and the elemental composition of the aerosol and thus fractionation. Emission from individual particles from solution nebulization, glass, and a pressed powder pellet are observed with high speed digital photography. The presence of intact particles in an ICP is shown to be a likely source of fractionation. A technique for the online detection of stimulated elemental release from neural tissue using magnetic sector ICP-MS is described. Detection limits of 1 μg L-1 or better were found for P, Mn, Fe, Cu, and Zn in a 60 μL injection in a physiological saline matrix.

  14. Encapsulation of anticancer drug and magnetic particles in biodegradable polymer nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Koneracka, M; Zavisova, V; Tomasovicova, N; Kopcansky, P; Timko, M; JurIkova, A; Csach, K; Kavecansky, V; Lancz, G [Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, Kosice (Slovakia); Muckova, M [Hameln rds a.s., Horna 36, Modra (Slovakia)], E-mail: konerack@saske.sk

    2008-05-21

    In this study, we have prepared PLGA (poly-D,L-lactide-co-glycolide) nanospheres loaded with biocompatible magnetic fluid and anticancer drug taxol by a modified nanoprecipitation technique and investigated their magnetic properties. A magnetic fluid, MF-PEG, with a biocompatible layer of polyethylene glycol (PEG), was chosen as a magnetic carrier. The PLGA, whose copolymer ratio of D,L-lactide to glycolide is 85:15, was utilized as a capsulation material. Taxol, as an important anticancer drug, was chosen for its significant role against a wide range of tumours. The morphology and particle size distributions of the prepared nanospheres were investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) and showed a spherical shape of prepared nanospheres with size 250 nm. Infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetry (TGA) analysis confirmed incorporation of magnetic particles and taxol into the PLGA polymer. The results showed good encapsulation with magnetite content 21.5 wt% and taxol 0.5 wt%. Magnetic properties of magnetic fluids and taxol within the PLGA polymer matrix were investigated by SQUID magnetometry from 4.2 to 300 K. The SQUID measurements showed superparamagnetism of prepared nanospheres with a blocking temperature of 160 K and saturation magnetization 1.4 mT.

  15. Apoferritin Modified Magnetic Particles as Doxorubicin Carriers for Anticancer Drug Delivery

    Directory of Open Access Journals (Sweden)

    Vojtech Adam

    2013-06-01

    Full Text Available Magnetic particle mediated transport in combination with nanomaterial based drug carrier has a great potential for targeted cancer therapy. In this study, doxorubicin encapsulation into the apoferritin and its conjugation with magnetic particles was investigated by capillary electrophoresis with laser-induced fluorescence detection (CE-LIF. The quantification of encapsulated doxorubicin was performed by fluorescence spectroscopy and compared to CE-LIF. Moreover, the significant enhancement of the doxorubicin signal was observed by addition of methanol into the sample solution.

  16. Building bio-assays with magnetic particles on a digital microfluidic platform.

    Science.gov (United States)

    Kokalj, Tadej; Pérez-Ruiz, Elena; Lammertyn, Jeroen

    2015-09-25

    Digital microfluidics (DMF) has emerged as a promising liquid handling technology for a variety of applications, demonstrating great potential both in terms of miniaturization and automation. DMF is based on the manipulation of discrete, independently controllable liquid droplets, which makes it highly reconfigurable and reprogrammable. One of its most exclusive advantages, compared to microchannel-based microfluidics, is its ability to precisely handle solid nano- and microsized objects, such as magnetic particles. Magnetic particles have become very popular in the last decade, since their high surface-to-volume ratio and the possibility to magnetically separate them from the matrix make them perfect suitable as a solid support for bio-assay development. The potential of magnetic particles in DMF-based bio-assays has been demonstrated for various applications. In this review we discuss the latest developments of magnetic particle-based DMF bio-assays with the aim to present, identify and analyze the trends in the field. We also discuss the state-of-the art of device integration, current status of commercialization and issues that still need to be addressed. With this paper we intend to stimulate researchers to exploit and unveil the potential of these exciting tools, which will shape the future of modern biochemistry, microbiology and biomedical diagnostics.

  17. A study of full particle orbit effects in stochastic magnetic fields

    Science.gov (United States)

    Ogawa, Shun; Cambon, Benjamin; Leoncini, Xavier; Del-Castillo Negrete, Diego; Vittot, Michel; Dif-Pradalier, Guilhem; Garbet, Xavier

    2015-11-01

    Full orbit effects of charged particle motion in a stochastic magnetic field are investigated. Particles move following the Lorentz force in a prescribed static magnetic field with no electric field in a cylinder with periodic boundary condition. The magnetic field model consists of the perturbation of equilibrium fields with monotonic and reversed shear q-profiles. Unlike the gyrokinetic theory, the adiabatic invariance of the magnetic momentum is not assumed, and the full Hamiltonian equations of motion are numerically integrated by using a symplectic method. Contrary to the simpler case of magnetic field line tracing, the dynamical properties of full orbit is not easily straightforward. To address this issue, we propose a method to construct reduced Poincaré plots from the full particle trajectory in three-dimensional space. This diagnostic is used to clarify the nontrivial relationship between the integrability and stochasticity of field lines and particle orbits. A problem of particular interest is the study of finite Larmor radius effects on the stochasticity and the topology of orbits.

  18. Statistical optimization of effective parameters on saturation magnetization of nanomagnetite particles

    Energy Technology Data Exchange (ETDEWEB)

    Ramimoghadam, Donya [Nanotechnology & Catalysis Research Centre (NANOCAT), IPS Building, University of Malaya, 50603 Kuala Lumpur (Malaysia); Bagheri, Samira, E-mail: samira_bagheri@edu.um.my [Nanotechnology & Catalysis Research Centre (NANOCAT), IPS Building, University of Malaya, 50603 Kuala Lumpur (Malaysia); Yousefi, Amin Termeh [ChECA IKohza, Department of Environmental & Green Technology (EGT), Malaysia Japan International Institute of Technology (MJIIT), University Technology Malaysia - UTM, Kuala Lumpur (Malaysia); Abd Hamid, Sharifah Bee [Nanotechnology & Catalysis Research Centre (NANOCAT), IPS Building, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-11-01

    In this study, nanomagnetite particles have been successfully prepared via the coprecipitation method. The effect of the key explanatory variables on the saturation magnetization of synthetic nanomagnetite particles was investigated using the response surface methodology (RSM). The correlation of the involved parameters with the growth process was examined by employing the central composite design method through designating set up experiments that will determine the interaction of the variables. The vibrating sample magnetometer (VSM) was used to confirm the statistical analysis. Furthermore, the regression analysis monitors the priority of the variables' influence on the saturation magnetization of nanomagnetite particles by developing the statistical model of the saturation magnetization. According to the investigated model, the highest interaction of variable belongs to the pH and temperature with the optimized condition of 9–11, and 75–85 °C, respectively. The response obtained by VSM suggests that the saturation magnetization of nanomagnetite particles can be controlled by restricting the effective parameters. - Highlights: • Nanomagnetite particles have been prepared via the coprecipitation method. • Effects of key variables on M{sub s} of synthetic nanomagnetite investigated by RSM. • The VSM was used to confirm the statistical analysis. • Optimized condition belongs to pH of 9–11, and temperature of 75–85 °C.

  19. The energetics of relativistic magnetic reconnection: ion-electron repartition and particle distribution hardness

    CERN Document Server

    Melzani, Mickaël; Folini, Doris; Winisdoerffer, Christophe; Favre, Jean M

    2014-01-01

    Collisionless magnetic reconnection is a prime candidate to account for flare-like or steady emission, outflow launching, or plasma heating, in a variety of high-energy astrophysical objects, including ones with relativistic ion-electron plasmas. But the fate of the initial magnetic energy in a reconnection event remains poorly known: what is the amount given to kinetic energy, the ion/electron repartition, and the hardness of the particle distributions? We explore these questions with 2D particle-in-cell simulations of ion-electron plasmas. We find that 45 to 75% of the total initial magnetic energy ends up in kinetic energy, this fraction increasing with the inflow magnetization. Depending on the guide field strength, ions get from 30 to 60% of the total kinetic energy. Particles can be separated into two populations that only weakly mix: (i) particles initially in the current sheet, heated by its initial tearing and subsequent contraction of the islands; and (ii) particles from the background plasma that p...

  20. Monte Carlo simulation of magnetization switching in a Heisenberg model for small ferromagnetic particles

    OpenAIRE

    Hinzke, Denise; Nowak, Ulrich

    1999-01-01

    Using Monte Carlo methods we investigate the thermally activated magnetization switching of small ferromagnetic particles driven by an external magnetic field. For low uniaxial anisotropy one expects that the spins rotate coherently while for sufficiently large anisotropy the reversal should be due to nucleation. The latter case has been investigated extensively by Monte Carlo simulation of corresponding Ising models. In order to study the crossover from coherent rotation to nucleation we use...

  1. Particle with spin 2 and anomalous magnetic moment in external electromagnetic and gravitational fields

    CERN Document Server

    Kisel, V V; Red'kov, V M

    2011-01-01

    Tensor 50-component form of the first order relativistic wave equation for a particle with spin 2 and anomalous magnetic moment is extended to the case of an arbitrary curved space-time geometry. An additional parameter considered in the presence of only electromagnetic field as related to anomalous magnetic moment, turns to determine additional interaction terms with external geometrical background through Ricci R_{kl} and Riemann R_{klmn} tensors.

  2. Effects of nearly massless, spin-zero particles on light propagation in a magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Maiani, L.; Petronzio, R.; Zavattini, E.

    1986-08-07

    Very light or massless spin-zero particles coupled to two photons, such as axions or genuine Goldstone bosons, induce small changes in the polarization state of a laser beam travelling in a magnetic field. Severe bounds on mass and coupling can be obtained through the observation of changes in polarization plane and ellipticity of the beam, at the level of accuracy allowed by present technologies. A positive signal would determine mass, coupling and parity of this hypothetical particle.

  3. Radiation of Relativistic Particles in a Quasi-Homogeneous Magnetic Field

    CERN Document Server

    Epp, V

    2016-01-01

    Spectrum of radiation of a relativistic particle moving in a nonhomogeneous magnetic field is considered. The spectrum depends on the pitch-angle $\\alpha$ between the velocity direction and a line tangent to the field line. In case of very small $\\alpha$ the particle generates so-called curvature radiation, in an intermediate case undulator-kind radiation is produced. In this paper we present the calculations of radiation properties in a case when both curvature and undulator radiation is observed.

  4. Monitoring of magnetic nano-particles in EOR by using the CSEM modeling and inversion.

    Science.gov (United States)

    Heo, J. Y.; KIM, S.; Jeong, G.; Hwang, J.; Min, D. J.

    2016-12-01

    EOR, which injects water, CO2, or other chemical components into reservoirs to increase the production rate of oil and gas, has widely been used. To promote efficiency of EOR, it is important to monitor distribution of injected materials in reservoirs. Using nano-particles in EOR has advantages that the size of particles is smaller than the pore and particles can be characterized by various physical properties. Specifically, if we use magnetic nano-particles, we can effectively monitor nano-particles by using the electromagnetic survey. CSEM, which can control the frequency range of source, is good to monitor magnetic nano-particles under various reservoir circumstances. In this study, we first perform numerical simulation of 3D CSEM for reservoir under production. In general, two wells are used for EOR: one is for injection, and the other is for extraction. We assume that sources are applied inside the injection well, and receivers are deployed inside the extraction well. To simulate the CSEM survey, we decompose the total fields into primary and secondary fields in Maxwell's equations. For the primary fields, we calculate the analytic solutions of the layered earth. With the calculated primary fields, we compute the secondary fields due to anomalies using the edge-based finite-element method. Finally, we perform electromagnetic inversion for both conductivity and permeability to trace the distribution of magnetic nano-particles. Since these two parameters react differently according to the frequency range of sources, we can effectively describe the distribution of magnetic nano-particles by considering two parameters at the same time. Acknowledgements This work was supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP) and the Ministry of Trade, Industry & Energy(MOTIE) of the Republic of Korea (No. 20168510030830), and by the International Cooperation (No. 2012-8510030010) of KETEP, and by the Dual Use Technology Program, granted

  5. Effect of magnetic anisotropy and particle size distribution on temperature dependent magnetic hyperthermia in Fe3O4 ferrofluids

    Science.gov (United States)

    Palihawadana Arachchige, Maheshika; Nemala, Humeshkar; Naik, Vaman; Naik, Ratna

    Magnetic hyperthermia (MHT) has a great potential as a non-invasive cancer therapy technique. Specific absorption rate (SAR) which measures the efficiency of heat generation, mainly depends on magnetic properties of nanoparticles such as saturation magnetization (Ms) and magnetic anisotropy (K) which depend on the size and shape. Therefore, MHT applications of magnetic nanoparticles often require a controllable synthesis to achieve desirable magnetic properties. We have synthesized Fe3O4 nanoparticles using two different methods, co-precipitation (CP) and hydrothermal (HT) techniques to produce similar XRD crystallite size of 12 nm, and subsequently coated with dextran to prepare ferrofluids for MHT. However, TEM measurements show average particle sizes of 13.8 +/-3.6 nm and 14.6 +/-3.6 nm for HT and CP samples, implying the existence of an amorphous surface layer for both. The MHT data show the two samples have very different SAR values of 110 W/g (CP) and 40W/g (HT) at room temperature, although they have similar Ms of 70 +/-4 emu/g regardless of their different TEM sizes. We fitted the temperature dependent SAR using linear response theory to explain the observed results. CP sample shows a larger magnetic core with a narrow size distribution and a higher K value compared to that of HT sample.

  6. Correlation between morphology and magnetic properties of electrochemically produced cobalt powder particles

    Directory of Open Access Journals (Sweden)

    Maksimović Vesna M.

    2015-01-01

    Full Text Available Cobalt 3D powder particles were successfully prepared by the galvanostatic electrodeposition. Electrodeposited cobalt powder were characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, Energy Dispersive Spectroscopy (EDS analysis and SQUID magnetometry. It has been shown that morphology, structure and magnetic properties of cobalt particles are closely associated and can be easily controlled by adjusting process parameters of electrodeposition. Morphology of cobalt powder particles is strongly affected by hydrogen evolution reaction as a parallel reaction to cobalt electrodeposition. Depending on the applied current density, the two types of powder particles were formed: dendrites at lower and spongy-like particles at higher current densities. Morphologies and structures of powder particles are correlated with their magnetic properties, and compared with those of the bulk cobalt. In comparison with the properties of bulk cobalt, the obtained 3D structures exhibited a decreased saturation magnetization (MS, but an enhanced coercivity (HC which is explained by their peculiar morphology. [Projekat Ministarstva nauke Republike Srbije, br. III 45012

  7. Size-Dependent Photodynamic Anticancer Activity of Biocompatible Multifunctional Magnetic Submicron Particles in Prostate Cancer Cells.

    Science.gov (United States)

    Choi, Kyong-Hoon; Nam, Ki Chang; Malkinski, Leszek; Choi, Eun Ha; Jung, Jin-Seung; Park, Bong Joo

    2016-09-06

    In this study, newly designed biocompatible multifunctional magnetic submicron particles (CoFe₂O₄-HPs-FAs) of well-defined sizes (60, 133, 245, and 335 nm) were fabricated for application as a photosensitizer delivery agent for photodynamic therapy in cancer cells. To provide selective targeting of cancer cells and destruction of cancer cell functionality, basic cobalt ferrite (CoFe₂O₄) particles were covalently bonded with a photosensitizer (PS), which comprises hematoporphyrin (HP), and folic acid (FA) molecules. The magnetic properties of the CoFe₂O₄ particles were finely adjusted by controlling the size of the primary CoFe₂O₄ nanograins, and secondary superstructured composite particles were formed by aggregation of the nanograins. The prepared CoFe₂O₄-HP-FA exhibited high water solubility, good MR-imaging capacity, and biocompatibility without any in vitro cytotoxicity. In particular, our CoFe₂O₄-HP-FA exhibited remarkable photodynamic anticancer efficiency via induction of apoptotic death in PC-3 prostate cancer cells in a particle size- and concentration-dependent manner. This size-dependent effect was determined by the specific surface area of the particles because the number of HP molecules increased with decreasing size and increasing surface area. These results indicate that our CoFe₂O₄-HP-FA may be applicable for photodynamic therapy (PDT) as a PS delivery material and a therapeutic agent for MR-imaging based PDT owing to their high saturation value for magnetization and superparamagnetism.

  8. Improving the design and analysis of superconducting magnets for particle accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Ramesh Chandra [Univ. of Rajasthan, Jaipur (India). Dept. of Physics

    1996-11-01

    High energy particle accelerators are now the primary means of discovering the basic building blocks of matter and understanding the forces between them. In order to minimize the cost of building these machines, superconducting magnets are used in essentially all present day high energy proton and heavy ion colliders. The cost of superconducting magnets is typically in the range of 20--30% of the total cost of building such machines. The circulating particle beam goes through these magnets a large number of times (over hundreds of millions). The luminosity performance and life time of the beam in these machines depends significantly on the field quality in these magnets. Therefore, even a small error in the magnetic field shape may create a large cumulative effect in the beam trajectory to throw the particles of the magnet aperture. The superconducting accelerator magnets must, therefore, be designed and constructed so that these errors are small. In this thesis the research and development work will be described 3which has resulted in significant improvements in the field quality of the superconducting magnets for the Relativistic Heavy Ion Collider (RHIC). The design and the field quality improvements in the prototype of the main collider dipole magnet for the Superconducting Super Collider (SSC) will also be presented. RHIC will accelerate and collide two counter rotating beams of heavy ions up to 100 GeV/u and protons up to 250 GeV. It is expected that RHIC will create a hot, dense quark-gluon plasma and the conditions which, according to the Big Bang theory, existed in the early universe.

  9. Biological Experiments in Microgravity Conditions Using Magnetic Micro- and Nano-Particles

    Science.gov (United States)

    Nechitailo, Galina S.; Kuznetsov, Anatoli; Kuznetsov, Oleg

    2016-07-01

    Gravity affects all living organisms on Earth, and plays a role in multiple processes in them. In microgravity conditions (e.g., on board of a spacecraft) many of these processes are disturbed, e.g., spatial orientation is lost, mass and heat exchange is distorted, many adaptive mechanisms no longer function, etc. Negation of these adverse effects by creation of pseudo-gravity to by centrifugation is complicated, expensive and unpractical. We propose to use naturally occurring magnetic heterogeneity of all living cells and high gradient magnetic fields as an alternative approach to negating the adverse effects of microgravity on living systems. In non-uniform magnetic field, magnetically heterogeneous objects experience a system of ponderomotive forces. For a weak magnetic particle, the net ponderomotive magnetic force: Fm = Δχ•V•grad(H2/2), where Δχ is the difference of susceptibilities of the particle and the surrounding media, V is the volume of the particle, grad(H2/2) is the dynamic factor of the magnetic field. We studied magnetic heterogeneity of plant gravity receptor cells, prepared and conducted experiments on board of the space station "Mir" on providing a gravity-like stimulus for flax seedlings using high gradient magnetic field ("Magnetogravistat" experiment). Later, a more sophisticated version of this experiment was flown on STS-107. These experiments provided new data on the mechanisms of plant gravity reception and created a method for substituting gravity for a living organism by a force of a different physical nature, to negate the adverse effects of microgravity. Since the ponderomotive force is proportional to the dynamic factor of the field grad(H2/2), the stronger the field, and the faster it changes over distance, the higher is the dynamic factor and the stronger the ponderomotive force. Therefore, in the small vicinity of a small ferromagnetic particle (preferably metallic micro or nano-particles), the forces are very significant

  10. Self-Magnetization of charged particles and Bose-Einstein Condensation

    CERN Document Server

    Rojas, H P; Cuesta, H M

    2004-01-01

    We discuss the Bose-Einstein condensation of relativistic vector charged particles in a strong external magnetic field in very dense matter, as may be paired spin-up electrons. We show that for electrons such systems may maintain self-consistently magnetic fields of order in between the interval $10^{10}-10^{13}$ Gauss. This could be the origin of large magnetic fields in some white dwarfs, but may also impose bounds due to the arising of strong anisotropy in the pressures, which may produce a transverse collapse of the star.

  11. Repeating Pulsed Magnet System for Axion-like Particle Searches and Vacuum Birefringence Experiments

    CERN Document Server

    Yamazaki, T; Namba, T; Asai, S; Kobayashi, T; Matsuo, A; Kindo, K; Nojiri, H

    2016-01-01

    We have developed a repeating pulsed magnet system which generates magnetic fields of about 10 T in a direction transverse to an incident beam over a length of 0.8 m with a repetition rate of 0.2 Hz. Its repetition rate is by two orders of magnitude higher than usual pulsed magnets. It is composed of four low resistance racetrack coils and a 30 kJ transportable capacitor bank as a power supply. The system aims at axion-like particle searches with a pulsed light source and vacuum birefringence measurements. We report on the details of the system and its performances.

  12. Repeating pulsed magnet system for axion-like particle searches and vacuum birefringence experiments

    Science.gov (United States)

    Yamazaki, T.; Inada, T.; Namba, T.; Asai, S.; Kobayashi, T.; Matsuo, A.; Kindo, K.; Nojiri, H.

    2016-10-01

    We have developed a repeating pulsed magnet system which generates magnetic fields of about 10 T in a direction transverse to an incident beam over a length of 0.8 m with a repetition rate of 0.2 Hz. Its repetition rate is by two orders of magnitude higher than usual pulsed magnets. It is composed of four low resistance racetrack coils and a 30 kJ transportable capacitor bank as a power supply. The system aims at axion-like particle searches with a pulsed light source and vacuum birefringence measurements. We report on the details of the system and its performances.

  13. Effect of carrier and particle concentration on ultrasound properties of magnetic nanofluids.

    Science.gov (United States)

    Patel, Jay Kumar; Parekh, Kinnari

    2015-01-01

    Ultrasound wave propagation in nanofluids and its rheological behavior has been studied as a function of solid volume fraction, temperature and magnetic field for magnetic nanofluids synthesized in kerosene and transformer oil. Ultrasonic velocity decreases while viscosity increases with increasing volume fraction. The attenuation of ultrasonic wave is explained using dipolar coupling co-efficient which favors oligomer structures with increasing number density of particles. The structure formation increases further with increase in magnetic field which is prominent in transformer oil compared to kerosene. This difference can be due to the structural difference between these two carriers.

  14. Dynamics of particles around a Schwarzschild-like black hole in the presence of quintessence and magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Jamil, Mubasher; Hussain, Saqib; Majeed, Bushra [National University of Sciences and Technology (NUST), School of Natural Sciences (SNS), Islamabad (Pakistan)

    2015-01-01

    We have investigated the dynamics of a neutral and a charged particle around a static and spherically symmetric black hole in the presence of quintessence matter and external magnetic field. We explore the conditions under which the particle moving around the black hole could escape to infinity after colliding with another particle. The innermost stable circular orbit (ISCO) for the particles are studied in detail. Mainly the dependence of ISCO on dark energy and on the presence of external magnetic field in the vicinity of black hole is discussed. By using the Lyapunov exponent, we compare the stabilities of the orbits of the particles in the presence and absence of dark energy and magnetic field. The expressions for the center of mass energies of the colliding particles near the horizon of the black hole are derived. The effective force on the particle due to dark energy and magnetic field in the vicinity of black hole is also discussed. (orig.)

  15. Coulomb scatter of diamagnetic dust particles in a cusp magnetic trap under microgravity conditions

    Energy Technology Data Exchange (ETDEWEB)

    Myasnikov, M. I., E-mail: miasnikovmi@mail.ru; D’yachkov, L. G.; Petrov, O. F.; Vasiliev, M. M., E-mail: mixxy@mail.ru; Fortov, V. E. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation); Savin, S. F.; Serova, E. O. [Korolev Rocket and Space Corporation Energia, ul. Lenina 4A (Russian Federation)

    2017-02-15

    The effect of a dc electric field on strongly nonideal Coulomb systems consisting of a large number (~10{sup 4}) of charged diamagnetic dust particles in a cusp magnetic trap are carried out aboard the Russian segment of the International Space Station (ISS) within the Coulomb Crystal experiment. Graphite particles of 100–400 μm in size are used in the experiments. Coulomb scatter of a dust cluster and the formation of threadlike chains of dust particles are observed experimentally. The processes observed are simulated by the molecular dynamics (MD) method.

  16. Functional Mimetics of the HIV-1 CCR5 Co-Receptor Displayed on the Surface of Magnetic Liposomes.

    Science.gov (United States)

    Kuzmina, Alona; Vaknin, Karin; Gdalevsky, Garik; Vyazmensky, Maria; Marks, Robert S; Taube, Ran; Engel, Stanislav

    2015-01-01

    Chemokine G protein coupled receptors, principally CCR5 or CXCR4, function as co-receptors for HIV-1 entry into CD4+ T cells. Initial binding of the viral envelope glycoprotein (Env) gp120 subunit to the host CD4 receptor induces a cascade of structural conformational changes that lead to the formation of a high-affinity co-receptor-binding site on gp120. Interaction between gp120 and the co-receptor leads to the exposure of epitopes on the viral gp41 that mediates fusion between viral and cell membranes. Soluble CD4 (sCD4) mimetics can act as an activation-based inhibitor of HIV-1 entry in vitro, as it induces similar structural changes in gp120, leading to increased virus infectivity in the short term but to virus Env inactivation in the long term. Despite promising clinical implications, sCD4 displays low efficiency in vivo, and in multiple HIV strains, it does not inhibit viral infection. This has been attributed to the slow kinetics of the sCD4-induced HIV Env inactivation and to the failure to obtain sufficient sCD4 mimetic levels in the serum. Here we present uniquely structured CCR5 co-receptor mimetics. We hypothesized that such mimetics will enhance sCD4-induced HIV Env inactivation and inhibition of HIV entry. Co-receptor mimetics were derived from CCR5 gp120-binding epitopes and functionalized with a palmitoyl group, which mediated their display on the surface of lipid-coated magnetic beads. CCR5-peptidoliposome mimetics bound to soluble gp120 and inhibited HIV-1 infectivity in a sCD4-dependent manner. We concluded that CCR5-peptidoliposomes increase the efficiency of sCD4 to inhibit HIV infection by acting as bait for sCD4-primed virus, catalyzing the premature discharge of its fusion potential.

  17. Functional Mimetics of the HIV-1 CCR5 Co-Receptor Displayed on the Surface of Magnetic Liposomes.

    Directory of Open Access Journals (Sweden)

    Alona Kuzmina

    Full Text Available Chemokine G protein coupled receptors, principally CCR5 or CXCR4, function as co-receptors for HIV-1 entry into CD4+ T cells. Initial binding of the viral envelope glycoprotein (Env gp120 subunit to the host CD4 receptor induces a cascade of structural conformational changes that lead to the formation of a high-affinity co-receptor-binding site on gp120. Interaction between gp120 and the co-receptor leads to the exposure of epitopes on the viral gp41 that mediates fusion between viral and cell membranes. Soluble CD4 (sCD4 mimetics can act as an activation-based inhibitor of HIV-1 entry in vitro, as it induces similar structural changes in gp120, leading to increased virus infectivity in the short term but to virus Env inactivation in the long term. Despite promising clinical implications, sCD4 displays low efficiency in vivo, and in multiple HIV strains, it does not inhibit viral infection. This has been attributed to the slow kinetics of the sCD4-induced HIV Env inactivation and to the failure to obtain sufficient sCD4 mimetic levels in the serum. Here we present uniquely structured CCR5 co-receptor mimetics. We hypothesized that such mimetics will enhance sCD4-induced HIV Env inactivation and inhibition of HIV entry. Co-receptor mimetics were derived from CCR5 gp120-binding epitopes and functionalized with a palmitoyl group, which mediated their display on the surface of lipid-coated magnetic beads. CCR5-peptidoliposome mimetics bound to soluble gp120 and inhibited HIV-1 infectivity in a sCD4-dependent manner. We concluded that CCR5-peptidoliposomes increase the efficiency of sCD4 to inhibit HIV infection by acting as bait for sCD4-primed virus, catalyzing the premature discharge of its fusion potential.

  18. Particle image velocimetry for an automatic cooling device using temperature-sensitive magnetic fluid

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    An automatic cooling device has been developed by using a temperature-sensitive magnetic fluid as the coolant. A particle image velocimetry (PIV) system was used to measure the flow velocity of the fluid inside the loop. The efficiency of the device under varying conditions such as the heat load and the power of cooling were ex- perimentally investigated. The effect of cooperation between external magnetic field and thermal field on the performance of the device was studied. As expected, a continuous flow induced by the thermal and magnetic field was observed in the loop, where heat was transferred by the circulating magnetic fluid. The synergic effect between the magnetic field and the temperature gradient has impact on the performance of the device.

  19. Particle image velocimetry for an automatic cooling device using temperature-sensitive magnetic fluid

    Institute of Scientific and Technical Information of China (English)

    LIAN WenLei; LI Qiang; XUAN YiMin

    2008-01-01

    An automatic cooling device has been developed by using a temperature-sensitive magnetic fluid as the coolant. A particle image velocimetry (PIV) system was used to measure the flow velocity of the fluid inside the loop. The efficiency of the device under varying conditions such as the heat load and the power of cooling were ex-perimentally investigated. The effect of cooperation between external magnetic field and thermal field on the performance of the device was studied. As expected, a continuous flow induced by the thermal and magnetic field was observed in the loop, where heat was transferred by the circulating magnetic fluid. The synergic effect between the magnetic field and the temperature gradient has impact on the performance of the device.

  20. Particle Transport along Magnetic Null Lines as Sputter or Antihydrogen Source

    Science.gov (United States)

    Lane, R. A.; Ordonez, C. A.

    Particle transport along null magnetic lines is investigated using classical trajectory Monte Carlo simulations and described as a traveling wave and through diffusion equations. A magnetic null line is defined as a one-dimensional region where the magnetic field magnitude is zero. This region may take any shape in three-dimensional space. The field used in the simulations is generated by two infinite wires of negligible thickness carrying identical current and separated by a small distance. Thus, an infinite magnetic null line exists directly between the wires. The particle trajectories are simulated by solving the equations of motion for each simulated particle of a mono- energetic set. Each is considered individually, with all trajectories starting from the same position along the null line. Each trajectory is simulated until it reaches a specified distance from the initial point or a maximum time elapses. The simulation is repeated using a full set for multiple endpoints and maximum times for ten different amounts of current in the wires. Each current value is selected so that no particles can travel more than seven times the distance between the wires from the null line. The fraction of particles that reach the endpoint in a given time is calculated and used to describe particle transport parallel to the null line. The results are given in normalized, dimensionless units and their possible applications as an antihydrogen source and use in ultra-high purity sputter are discussed. The results are used to find the conditions necessary to obtain a steady and uniform particle flux suitable for ultra-high purity sputter, assuming that plasma is generated near the null line.

  1. A series of tetrathiafulvalene-based lanthanide complexes displaying either single molecule magnet or luminescence-direct magnetic and photo-physical correlations in the ytterbium analogue.

    Science.gov (United States)

    Pointillart, Fabrice; Le Guennic, Boris; Cauchy, Thomas; Golhen, Stéphane; Cador, Olivier; Maury, Olivier; Ouahab, Lahcène

    2013-05-20

    The reaction between (4,5-bis(2-pyridyl-N-oxidemethylthio)-4',5')-ethylenedithiotetrathiafulvene (L(1)) or -methyldithiotetrathiafulvene (L(2)) ligands and Ln(hfac)3·nH2O precursors (Ln(III) = Pr, Tb, Dy, Er, and Yb) leads to the formation of seven dinuclear complexes of formula [Ln2(hfac)6(H2O)x(L(y))2] (x = 2 and y = 1 for Ln(III) = Pr (1); x = 0 and y = 1 for Ln(III) = Tb (2), Dy (3), Er (4) and Yb (5); x = 0 and y = 2 for Ln(III) = Tb (6) and Dy (7)). Their X-ray structures reveal that the coordination environment of each Ln(III) center is filled by two N-oxide groups coming from two different ligands L(y). UV-visible absorption properties have been experimentally measured and rationalized by TD-DFT calculations. The temperature dependences of static magnetic measurements have been fitted. The ground state corresponds to the almost pure |M(J) = ±13/2〉 while the first excited state (±0.77|±11/2〉 ± 0.50|±3/2〉 ± 0.39|±5/2〉) is located at 19 cm(-1) and 26.9 cm(-1) respectively for 3 and 7. Upon irradiation at 77 K and at room temperature, in the range 25,000-20,835 cm(-1), both compounds 4 and 5 display a metal-centered luminescence attributed to (4)I(13/2) → (4)I(15/2) (6660 cm(-1)) and (2)F(5/2) → (2)F(7/2) (9972 cm(-1)) transitions, respectively. Emission spectroscopy provides a direct probe of the |±5/2〉 ground state multiplet splitting, which has been confronted to magnetic data. The energy separation of 225 cm(-1) between the ground state and the first excited level (M(J) = ±3/2) fits exactly the second emission line (234 cm(-1)). While no out-phase-signal is detected for 3, the change of ligand L(1) → L(2) induces a change of coordination sphere symmetry around the Dy(III) increasing the energy splitting between the ground and first excited states, and 7 displays a single molecule magnet behavior.

  2. Field-tuned quantum tunnelling of the magnetization in small magnetic particles

    NARCIS (Netherlands)

    García-Pablos, D.; García, N.; Raedt, H. De

    1998-01-01

    We present staircase magnetization curves for single-spin models of uniaxial magnets as obtained from the numerically exact solution of the time-dependent Schrödinger equation. Steps are shown to correspond to field-tuned tunnelling between different pairs of nearly degenerate energy levels. The rol

  3. Interface deformations affect the orientation transition of magnetic ellipsoidal particles adsorbed at fluid–fluid interfaces

    NARCIS (Netherlands)

    Davies, G.; Kruger, T.; Coveney, P.V.; Harting, J.D.R.; Bresme, F.

    2014-01-01

    Manufacturing new soft materials with specific optical, mechanical and magnetic properties is a significant challenge. Assembling and manipulating colloidal particles at fluid interfaces is a promising way to make such materials. We use lattice-Boltzmann simulations to investigate the response of ma

  4. Exact solutions for quantum mechanical particle with spin 1 in the external homogeneous magnetic field

    CERN Document Server

    Kisel, V V; Red'kov, V M

    2010-01-01

    With the use of the general covariant matrix 10-dimensional Petiau -- Duffin -- Kemmer formalism in cylindrical coordinates and tetrad there are constructed exact solutions of the quantum-mechanical equation for a particle with spin 1 in presence of an external homogeneous magnetic field. There are separated three linearly independent types of solutions; in each case the formula for energy levels has been found.

  5. Cylindrical active coated nano-particles excited by electric and magnetic line sources

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Liu, Y.; Malureanu, Radu

    2011-01-01

    Cylindrical active coated nano-particles comprised of a silica nano-cylinder core covered with a plasmonic nano-shell are investigated with regard to their near- and far-field properties. The source of excitation is taken to be an electric or a magnetic line current, while three different plasmonic...

  6. Cylindrical active coated nano-particles excited by electric and magnetic line sources

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Liu, Y.; Malureanu, Radu

    2011-01-01

    Cylindrical active coated nano-particles comprised of a silica nano-cylinder core covered with a plasmonic nano-shell are investigated with regard to their near- and far-field properties. The source of excitation is taken to be an electric or a magnetic line current, while three different plasmonic...

  7. Eddy Current, Magnetic Particle and Hardness Testing, Aviation Quality Control (Advanced): 9227.04.

    Science.gov (United States)

    Dade County Public Schools, Miami, FL.

    This unit of instruction includes the principles of eddy current, magnetic particle and hardness testing; standards used for analyzing test results; techniques of operating equipment; interpretation of indications; advantages and limitations of these methods of testing; care and calibration of equipment; and safety and work precautions. Motion…

  8. Interface deformations affect the orientation transition of magnetic ellipsoidal particles adsorbed at fluid–fluid interfaces

    NARCIS (Netherlands)

    Davies, G.; Kruger, T.; Coveney, P.V.; Harting, Jens Dieter Rolf; Bresme, F.

    2014-01-01

    Manufacturing new soft materials with specific optical, mechanical and magnetic properties is a significant challenge. Assembling and manipulating colloidal particles at fluid interfaces is a promising way to make such materials. We use lattice-Boltzmann simulations to investigate the response of

  9. An electrochemical immunosensor for carcinoembryonic antigen enhanced by self-assembled nanogold coatings on magnetic particles.

    Science.gov (United States)

    Li, Jianping; Gao, Huiling; Chen, Zhiqiang; Wei, Xiaoping; Yang, Catherine F

    2010-04-14

    A quick and reproducible electrochemical-based immunosensor technique, using magnetic core/shell particles that are coated with self-assembled multilayer of nanogold, has been developed. Magnetic particles that are structured from Au/Fe(3)O(4) core-shells were prepared and aminated after a reaction between gold and thiourea, and additional multilayered coatings of gold nanoparticles were assembled on the surface of the core/shell particles. The carcinoembryonic antibody (anti-CEA) was immobilized on the modified magnetic particles, which were then attached on the surface of solid paraffin carbon paste electrode (SPCE) by an external magnetic field. This is an assembly of a novel immuno biosensor for carcinoembryonic antigen (CEA). The sensitivity and response features of this immunoassay are significantly affected by the surface area and the biological compatibility of the multilayered nanogold. The linear range for the detection of CEA was from 0.005 to 50 ng mL(-1) and the limit of detection (LOD) was 0.001 ng mL(-1). The LOD is approximately 500 times more sensitive than that of the traditional enzyme-linked immunosorbent assay for CEA detection.

  10. High saturation magnetization of γ-Fe2O3 nano-particles by a facile one-step synthesis approach

    Science.gov (United States)

    Cao, Derang; Li, Hao; Pan, Lining; Li, Jianan; Wang, Xicheng; Jing, Panpan; Cheng, Xiaohong; Wang, Wenjie; Wang, Jianbo; Liu, Qingfang

    2016-09-01

    We have demonstrated the synthesis of γ-Fe2O3 nano-particles through a facile and novel calcination process in the air. There is no pH regulation, gas atmosphere, additive, centrifugation or other complicated procedures during the preparing process. A detailed formation process of the nano-particles is proposed, and DMF as a polar solvent may slower the reaction process of calcination. The structures, morphologies, and magnetic properties of γ-Fe2O3 nano-particles were investigated systematically, and the pure γ-Fe2O3 nano-particles obtained at 200 °C display uniform morphology good magnetic property. The saturation magnetization of obtained pure γ-Fe2O3 is about 74 emu/g, which is comparable with bulk material (76 emu/g) and larger than other results. In addition, the photocatalytic activity for degradation of methylene blue is also studied, which shows proper photocatalytic activity.

  11. Simulations of ion acceleration at non-relativistic shocks: ii) magnetic field amplification and particle diffusion

    CERN Document Server

    Caprioli, Damiano

    2014-01-01

    We use large hybrid (kinetic ions-fluid electrons) simulations to study ion acceleration and generation of magnetic turbulence due to the streaming of energetic particles that are self-consistently accelerated at non-relativistic shocks. When acceleration is efficient (at quasi-parallel shocks), we find that the magnetic field develops transverse components and is significantly amplified in the pre-shock medium. The total amplification factor is larger than 10 for shocks with Mach number $M=100$, and scales with the square root of $M$. We find that in the shock precursor the energy spectral density of excited magnetic turbulence is proportional to spectral energy distribution of accelerated particles at corresponding resonant momenta, in good agreement with the predictions of quasilinear theory of diffusive shock acceleration. We discuss the role of Bell's instability, which is predicted and found to grow faster than resonant instability in shocks with $M\\gtrsim 30$. Ahead of these strong shocks we distinguis...

  12. Modeling of radio emission from a particle cascade in a magnetic field and its experimental validation

    Science.gov (United States)

    Zilles, Anne

    2017-03-01

    The SLAC T-510 experiment was designed to compare controlled laboratory measurements of radio emission of particle showers to predictions using particle-level simulations, which are relied upon in ultra-high-energy cosmic-ray air shower detection. Established formalisms for the simulation of radio emission physics, the "endpoint" formalism and the "ZHS" formalism, lead to results which can be explained by a superposition of magnetically induced transverse current radiation and charge-excess radiation due to the Askaryan effect. Here, we present the results of Geant4 simulations for the SLAC T-510 experiment, taking into account the details of the experimental setup (beam energy, target geometry and material, magnetic field configuration, and refraction effects) and their comparison to measured data with respect to e.g. signal polarisation, linearity with magnetic field, and angular distribution. We find that the microscopic calculations reproduce the measurements within uncertainties and describe the data well.

  13. Electron-scale shear instabilities: magnetic field generation and particle acceleration in astrophysical jets

    CERN Document Server

    Alves, E P; Fonseca, R A; Silva, L O

    2014-01-01

    Strong shear flow regions found in astrophysical jets are shown to be important dissipation regions, where the shear flow kinetic energy is converted into electric and magnetic field energy via shear instabilities. The emergence of these self-consistent fields make shear flows significant sites for radiation emission and particle acceleration. We focus on electron-scale instabilities, namely the collisionless, unmagnetized Kelvin-Helmholtz instability (KHI) and a large-scale dc magnetic field generation mechanism on the electron scales. We show that these processes are important candidates to generate magnetic fields in the presence of strong velocity shears, which may naturally originate in energetic matter outburst of active galactic nuclei and gamma-ray bursters. We show that the KHI is robust to density jumps between shearing flows, thus operating in various scenarios with different density contrasts. Multidimensional particle-in-cell (PIC) simulations of the KHI, performed with OSIRIS, reveal the emergen...

  14. Magnetic nanocomposites of periodic mesoporous silica: The influence of the silica substrate dimensionality on the inter-particle magnetic interactions

    Energy Technology Data Exchange (ETDEWEB)

    Zeleňáková, Adriana, E-mail: azelenak@upjs.sk [Department of Solid State Physics, P.J. Šafárik University, Park Angelinum 9, Košice (Slovakia); Zeleňák, Vladimir [Department of Inorganic Chemistry, P.J. Šafárik University, Moyzesova 11, Košice (Slovakia); Bednarčík, Jozef [DESY-Hasylab, Notkestrasse 85, Hamburg (Germany); Hrubovčák, Pavol [Department of Solid State Physics, P.J. Šafárik University, Park Angelinum 9, Košice (Slovakia); Kováč, Jozef [Institute of Experimental Physics, SAS, Watsonova 41, Košice (Slovakia)

    2014-01-05

    Highlights: • Hematite particles inside porous silica with 2D hexagonal and 3D cubic symmetry. • Magnetic properties are strongly affected by the dimensionality of porous matrix. • Weak dipolar interactions observed in superparamagnetic hexagonal α-Fe{sub 2}O{sub 3}@SBA-15. • Strong interactions leading to superspin-glass observed in cubic α-Fe{sub 2}O{sub 3}@SBA-16. -- Abstract: Magnetic nanocomposites consisting of iron oxide (hematite, α-Fe{sub 2}O{sub 3}) nanoparticles loaded into the pores of the periodically ordered mesoporous silica with hexagonal (SBA-15) or cubic (SBA-16) symmetry were investigated. The characterization of the samples was carried out by N{sub 2} adsorption/desorption, Small-angle X-ray scattering (SAXS), High-energy X-ray diffraction (HE-XRD) and HRTEM measurements. The magnetic properties of the prepared nanocomposites were investigated by the SQUID magnetometry. It was shown, that in spite of its non-magnetic nature the silica matrix significantly influences the magnetism of the samples. The magnetic properties are strongly affected by the strength of inter-particle interactions and dimensionality of the porous matrix. Weak dipolar interactions between superparamagnetic (SPM) hematite nanoparticles were observed in the nanocomposite with hexagonally ordered silica channels (α-Fe{sub 2}O{sub 3}@SBA-15), while the strong interactions between hematite nanoparticles, suggesting the superspin glass behavior (SSG), were observed in the nanocomposite with silica matrix of cubic symmetry (α-Fe{sub 2}O{sub 3}@SBA-16)

  15. Two dimensional, electronic particle tracking in liquids with a graphene-based magnetic sensor array

    Science.gov (United States)

    Neumann, Rodrigo F.; Engel, Michael; Steiner, Mathias

    2016-07-01

    The investigation and control of liquid flow at the nanometer scale is a key area of applied research with high relevance to physics, chemistry, and biology. We introduce a method and a device that allows the spatial resolution of liquid flow by integrating an array of graphene-based magnetic (Hall) sensors that is used for tracking the movement of magnetic nanoparticles immersed in a liquid under investigation. With a novel device concept based on standard integration processes and experimentally verified material parameters, we numerically simulate the performance of a single sensor pixel, as well as the whole sensor array, for tracking magnetic nanoparticles having typical properties. The results demonstrate that the device enables (a) the detection of individual nanoparticles in the liquid with high accuracy and (b) the reconstruction of a particle's flow-driven trajectory across the integrated sensor array with sub-pixel precision as a function of time, in what we call the ``Magnetic nanoparticle velocimetry'' technique. Since the method does not rely on optical detection, potential lab-on-chip applications include particle tracking and flow analysis in opaque media at the sub-micron scale.The investigation and control of liquid flow at the nanometer scale is a key area of applied research with high relevance to physics, chemistry, and biology. We introduce a method and a device that allows the spatial resolution of liquid flow by integrating an array of graphene-based magnetic (Hall) sensors that is used for tracking the movement of magnetic nanoparticles immersed in a liquid under investigation. With a novel device concept based on standard integration processes and experimentally verified material parameters, we numerically simulate the performance of a single sensor pixel, as well as the whole sensor array, for tracking magnetic nanoparticles having typical properties. The results demonstrate that the device enables (a) the detection of individual

  16. Formation of hard power laws in the energetic particle spectra resulting from relativistic magnetic reconnection.

    Science.gov (United States)

    Guo, Fan; Li, Hui; Daughton, William; Liu, Yi-Hsin

    2014-10-10

    Using fully kinetic simulations, we demonstrate that magnetic reconnection in relativistic plasmas is highly efficient at accelerating particles through a first-order Fermi process resulting from the curvature drift of particles in the direction of the electric field induced by the relativistic flows. This mechanism gives rise to the formation of hard power-law spectra in parameter regimes where the energy density in the reconnecting field exceeds the rest mass energy density σ ≡ B(2)/(4πnm(e)c(2))>1 and when the system size is sufficiently large. In the limit σ ≫ 1, the spectral index approaches p = 1 and most of the available energy is converted into nonthermal particles. A simple analytic model is proposed which explains these key features and predicts a general condition under which hard power-law spectra will be generated from magnetic reconnection.

  17. The Effect of Particle Concentration on the Heating Rate of Ferrofluids for Magnetic Hyperthermia

    Directory of Open Access Journals (Sweden)

    Malaescu I.

    2015-12-01

    Full Text Available The complex magnetic susceptibility χ(f = χ′(f - i χ″(f, of a ferrofluid sample with magnetite particles dispersed in kerosene and stabilized with oleic acid, over the range 0.1 GHz to 6 GHz, was determined. The initial sample has been successively diluted with kerosene (with a dilution rate of 2/3, thus obtaining further three samples. Using the complex magnetic susceptibility measurements of each sample, the frequency field and particle concentration dependencies of the heating rate of the ferrofluid samples, were analyzed. The results show the possibility of using the heating rate of ferrofluid samples with different particle concentrations, in hyperthermia applications.

  18. Dynamics of magnetically trapped particles foundations of the physics of radiation belts and space plasmas

    CERN Document Server

    Roederer, Juan G

    2014-01-01

    This book is a new edition of Roederer’s classic Dynamics of Geomagnetically Trapped Radiation, updated and considerably expanded. The main objective is to describe the dynamic properties of magnetically trapped particles in planetary radiation belts and plasmas and explain the physical processes involved from the theoretical point of view. The approach is to examine in detail the orbital and adiabatic motion of individual particles in typical configurations of magnetic and electric fields in the magnetosphere and, from there, derive basic features of the particles’ collective “macroscopic” behavior in general planetary environments. Emphasis is not on the “what” but on the “why” of particle phenomena in near-earth space, providing a solid and clear understanding of the principal basic physical mechanisms and dynamic processes involved. The book will also serve as an introduction to general space plasma physics, with abundant basic examples to illustrate and explain the physical origin of diff...

  19. Particle capture in axial magnetic filters with power law flow model

    CERN Document Server

    Abbasov, T; Koksal, M

    1999-01-01

    A theory of capture of magnetic particle carried by laminar flow of viscous non-Newtonian (power law) fluid in axially ordered filters is presented. The velocity profile of the fluid flow is determined by the Kuwabara-Happel cell model. For the trajectory of the particle, the capture area and the filter performance simple analytical expressions are obtained. These expressions are valid for particle capture processes from both Newtonian and non-Newtonian fluids. For this reason the obtained theoretical results make it possible to widen the application of high-gradient magnetic filtration (HGMF) to other industrial areas. For Newtonian fluids the theoretical results are shown to be in good agreement with the experimental ones reported in the literature. (author)

  20. Particle capture in axial magnetic filters with power law flow model

    Science.gov (United States)

    Abbasov, T.; Herdem, S.; Köksal, M.

    1999-05-01

    A theory of capture of magnetic particle carried by laminar flow of viscous non-Newtonian (power law) fluid in axially ordered filters is presented. The velocity profile of the fluid flow is determined by the Kuwabara-Happel cell model. For the trajectory of the particle, the capture area and the filter performance simple analytical expressions are obtained. These expressions are valid for particle capture processes from both Newtonian and non-Newtonian fluids. For this reason the obtained theoretical results make it possible to widen the application of high-gradient magnetic filtration (HGMF) to other industrial areas. For Newtonian fluids the theoretical results are shown to be in good agreement with the experimental ones reported in the literature.

  1. Particle capture in axial magnetic filters with power law flow model

    Energy Technology Data Exchange (ETDEWEB)

    Abbasov, T.; Herdem, S.; Koksal, M. [Inonu University, Engineering Faculty, Department of Electrical and Electronics, Malatya (Turkey)

    1999-05-21

    A theory of capture of magnetic particle carried by laminar flow of viscous non-Newtonian (power law) fluid in axially ordered filters is presented. The velocity profile of the fluid flow is determined by the Kuwabara-Happel cell model. For the trajectory of the particle, the capture area and the filter performance simple analytical expressions are obtained. These expressions are valid for particle capture processes from both Newtonian and non-Newtonian fluids. For this reason the obtained theoretical results make it possible to widen the application of high-gradient magnetic filtration (HGMF) to other industrial areas. For Newtonian fluids the theoretical results are shown to be in good agreement with the experimental ones reported in the literature. (author)

  2. Technogenic Magnetic Particles in Alkaline Dusts from Power and Cement Plants.

    Science.gov (United States)

    Magiera, Tadeusz; Gołuchowska, Beata; Jabłońska, Mariola

    2013-01-01

    During this study, we investigated the mineralogical characterization of technogenic magnetic particles (TMPs) contained in alkaline industrial dust and fly ash emitted by coal burning power plants and cement plants. The reaction of tested dust samples varied between values of pH 8 and pH 12. Their magnetic properties were characterized by measurement of magnetic susceptibility (χ), frequency dependence of magnetic susceptibility (χ(fd)), and temperature dependence of magnetic susceptibility. Mineralogical and geochemical analyses included scanning electron microscopy with energy dispersive spectroscopy, microprobe analysis and X-ray diffraction. The TMPs in fly ash from hard coal combustion have the form of typical magnetic spherules with a smooth or corrugated surface as well as a skeletal morphology, composed of iron oxides (magnetite, maghemite, and magnesioferrite) that occurred in the form of incrustation on the surface of mullite, amorphous silica, or aluminosilicate particles. The TMPs observed in fly ash from lignite combustion have a similar morphological form but a different mineralogical composition. Instead of magnetite and magnesioferrite, maghemite and hematite with lower χ values were the prevailing magnetic minerals, which explains the much lower magnetic susceptibility of this kind of ash in comparison with the ash from hard coal combustion, and probably results from the lower temperature of lignite combustion. Morphology and mineralogical composition of TMPs in cement dust is more diverse. The magnetic fraction of cement dust occurs mostly in the form of angular and octahedral grains of a significantly finer granulation (cement dust is calcium ferrite (CaFe(3)O(5)). The greatest impact on the magnetic susceptibility of cement dust results from iron-bearing additives (often waste materials from other branches of industry), which should be considered the most dangerous to the environment. Stoichiometric analysis of micro-particles confirmed

  3. Factors affecting magnetic retention of particles in the upper airways: an in vitro and ex vivo study.

    Science.gov (United States)

    Ally, J; Amirfazli, A; Roa, W

    2006-01-01

    This paper presents the results of experiments using an in vitro model and an ex vivo animal model (Rana catesbeiana) to study magnetic particle retention in the conducting airways, specifically the trachea and bronchi. The purpose of these experiments was to determine the significant factors for retention of magnetic particles deposited from an aerosol at the airway surface using a magnetic field. The results indicate that the apparent viscosity of the mucus layer at low shear rates is the most significant obstacle to particle retention. The results also show that particle size and aggregation play major roles in particle retention. The mucus transport rate, unlike the effect of fluid velocity in intravenous applications, did not appear to be a determining factor for particle retention. It was also found that a suitably designed magnetic system, aside from having a high intensity, needs to exert a strong radial field to promote particle aggregation. The findings suggest that one possible approach to magnetic particle retention could be delivery of a mucolytic agent along with the drug particles. This study provides the fundamentals needed for development of a targeted magnetic drug delivery system for inhaled therapeutic aerosol particles.

  4. Fe3O4/BSA particles induce osteogenic differentiation of mesenchymal stem cells under static magnetic field.

    Science.gov (United States)

    Jiang, Pengfei; Zhang, Yixian; Zhu, Chaonan; Zhang, Wenjing; Mao, Zhengwei; Gao, Changyou

    2016-12-01

    Differentiation of stem cells is influenced by many factors, yet uptake of the magnetic particles with or without magnetic field is rarely tackled. In this study, iron oxide nanoparticles-loaded bovine serum albumin (BSA) (Fe3O4/BSA) particles were prepared, which showed a spherical morphology with a diameter below 200 nm, negatively charged surface, and tunable magnetic property. The particles could be internalized into bone marrow mesenchymal stem cells (MSCs), and their release from the cells was significantly retarded under external magnetic field, resulting in almost twice intracellular amount of the particles within 21 d compared to that of the magnetic field free control. Uptake of the Fe3O4/BSA particles enhanced significantly the osteogenic differentiation of MSCs under a static magnetic field, as evidenced by elevated alkaline phosphatase (ALP) activity, calcium deposition, and expressions of collagen type I and osteocalcin at both mRNA and protein levels. Therefore, uptake of the Fe3O4/BSA particles brings significant influence on the differentiation of MSCs under magnetic field, and thereby should be paid great attention for practical applications. Differentiation of stem cells is influenced by many factors, yet uptake of the magnetic particles with or without magnetic field is rarely tackled. In this study, iron oxide nanoparticles-loaded bovine serum albumin (BSA) (Fe3O4/BSA) particles with a diameter below 200nm, negatively charged surface, tunable Fe3O4 content and subsequently adjustable magnetic property were prepared. The particles could be internalized into bone marrow mesenchymal stem cells (MSCs), and their release from the cells was significantly retarded under external magnetic field. Uptake of the Fe3O4/BSA particles enhanced significantly the osteogenic differentiation of MSCs under a constant static magnetic field, while the magnetic particles and external magnetic field alone do not influence significantly the osteogenic differentiation

  5. The Effect of Magnetic Topology on the Escape of Flare Particles

    Science.gov (United States)

    Antiochos, S. K.; Masson, S.; DeVore, C. R.

    2012-01-01

    Magnetic reconnection in the solar atmosphere is believed to be the driver of most solar explosive phenomena. Therefore, the topology of the coronal magnetic field is central to understanding the solar drivers of space weather. Of particular importance to space weather are the impulsive Solar Energetic particles that are associated with some CME/eruptive flare events. Observationally, the magnetic configuration of active regions where solar eruptions originate appears to agree with the standard eruptive flare model. According to this model, particles accelerated at the flare reconnection site should remain trapped in the corona and the ejected plasmoid. However, flare-accelerated particles frequently reach the Earth long before the CME does. We present a model that may account for the injection of energetic particles onto open magnetic flux tubes connecting to the Earth. Our model is based on the well-known 2.5D breakout topology, which has a coronal null point (null line) and a four-flux system. A key new addition, however, is that we include an isothermal solar wind with open-flux regions. Depending on the location of the open flux with respect to the null point, we find that the flare reconnection can consist of two distinct phases. At first, the flare reconnection involves only closed field, but if the eruption occurs close to the open field, we find a second phase involving interchange reconnection between open and closed. We argue that this second reconnection episode is responsible for the injection of flare-accelerated particles into the interplanetary medium. We will report on our recent work toward understanding how flare particles escape to the heliosphere. This work uses high-resolution 2.5D MHD numerical simulations performed with the Adaptively Refined MHD Solver (ARMS).

  6. Magnetic turbulence and particle dynamics in the Earth’s magnetotail

    Directory of Open Access Journals (Sweden)

    G. Zimbardo

    Full Text Available The influence of magnetic turbulence in the near-Earth magnetotail on ion motion is investigated by numerical simulation. The magnetotail current sheet is modelled as a magnetic field reversal with a normal magnetic field com-ponent Bn , plus a three-dimensional spectrum of magnetic fluctuations dB which represents the observed magnetic turbulence. The dawn-dusk electric field Ey is also considered. A test particle simulation is performed using different values of Bn and of the fluctuation level dB/B0. We show that when the magnetic fluctuations are taken into account, the particle dynamics is deeply affected, giving rise to an increase in the cross tail transport, ion heating, and current sheet thickness. For strong enough turbulence, the current splits in two layers, in agreement with recent Cluster observations.

    Key words. Magnetospheric physics (magnetospheric configuration and dynamics – Interplanetary physics (MHD waves and turbulence – Electromagnetics (numerical methods

  7. Spin Switch and Qubit Register from a Spin Particle Controlled by a Time-Dependent Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    WANG Shun-Jin; JIA Cheng-Long; AN Jun-Hong; LUO Hong- Gang

    2004-01-01

    @@ A spin particle subjected to any time-dependent magnetic field is investigated in detail at different magnetic field configurations. Spin flip probability, spin alignment, cyclic and noncyclic nonadiabatic geometric phases are calculated exactly and their analytical expressions are presented. Our theoretical study shows that a spin particle controlled by a resonant time-dependent magnetic field can be used as efficient controllable devices of spin switch or qubit register.

  8. 1999 Review of superconducting dipole and quadrupole magnets for particle accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Devred, A. [CEA/Saclay, Dept. d' Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l' Instrumentation Associee (DAPNIA), 91 - Gif-sur-Yvette (France); CERN, Conseil Europeen pour la recherche nucleaire, Laboratoire europeen pour la physique des particules Geneve (Switzerland)

    1999-12-01

    The quest for elementary particles has promoted the development of particle accelerators producing beams of increasingly higher energies. In a synchrotron-type accelerator, the particle energy is directly proportional to the product of the machine's radius times the bending magnets' field strength. Present proton experiments at the TeV scale require facilities with circumferences ranging from a few to tens of kilometers and relying on a large number (several hundreds to several thousands) of high field dipole magnets and high field gradient quadrupole magnets. These electro-magnets use high current density, low critical temperature superconducting cables and are cooled down at liquid helium temperature. They are among the most costly and the most challenging components of the machine. After explaining what are the various types of accelerator magnets and why they are needed (section 1), we present a brief history of large superconducting particle accelerators, and we detail ongoing superconducting accelerator magnet R and D programs around the world (Section 2). Then, we review the superconducting materials that are available at industrial scale (chiefly, NbTi and Nb3Sn), and we describe the manufacturing of NbTi wires and cables (section 3). We also present the difficulties of processing and insulating Nb3Sn conductors which, so far, have limited the use of this material in spite of its superior performances. We continue by presenting the complex formalism used to represent two-dimensional fields (section 4), and we discuss the two-dimensional current distributions that are the most appropriate for generating pure dipole and pure quadrupole fields (section 5). We explain how these ideal distributions can be approximated by so-called cos{theta} and cos{sup 2}{theta} coil designs and we describe the difficulties of realizing coil ends. Next, we present the mechanical design concepts that have been developed to restrain magnet coils and to ensure proper

  9. Particle-In-Cell Simulations of the Solar Wind Interaction with Lunar Crustal Magnetic Anomalies: Magnetic Cusp Regions

    Science.gov (United States)

    Poppe, A. R.; Halekas, J. S.; Delory, G. T.; Farrell, W. M.

    2012-01-01

    As the solar wind is incident upon the lunar surface, it will occasionally encounter lunar crustal remanent magnetic fields. These magnetic fields are small-scale, highly non-dipolar, have strengths up to hundreds of nanotesla, and typically interact with the solar wind in a kinetic fashion. Simulations, theoretical analyses, and spacecraft observations have shown that crustal fields can reflect solar wind protons via a combination of magnetic and electrostatic reflection; however, analyses of surface properties have suggested that protons may still access the lunar surface in the cusp regions of crustal magnetic fields. In this first report from a planned series of studies, we use a 1 1/2-dimensional, electrostatic particle-in-cell code to model the self-consistent interaction between the solar wind, the cusp regions of lunar crustal remanent magnetic fields, and the lunar surface. We describe the self-consistent electrostatic environment within crustal cusp regions and discuss the implications of this work for the role that crustal fields may play regulating space weathering of the lunar surface via proton bombardment.

  10. Magnetic properties, microstructure and mineralogical phases of technogenic magnetic particles (TMPs) in urban soils: Their source identification and environmental implications

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Shenggao, E-mail: lusg@zju.edu.cn [College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Yu, Xiuling [College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Chen, Yuyin [Institute of Biological Resources, Zhejiang University, Hangzhou 310058 (China)

    2016-02-01

    Magnetic measurement is an effective method to determine spatial distribution and the degree of heavy metal pollution and to identify various anthropogenic sources of heavy metals. The objectives of this investigation are to characterize the magnetic properties, microstructure and mineralogical phases of technogenic magnetic particles (TMPs) in urban soils and to discuss their potential environmental implications. The TMPs are separated from the urban topsoils of Luoyang city, China. The magnetic properties, morphology, and mineral phase of TMPs are studied using mineral magnetic measurement, scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM/EDS), X-ray diffraction, and synchrotron–radiation-based microprobe. The content of TMPs in urban topsoils ranges from 0.05 to 1.95% (on average 0.32%). The magnetic susceptibility of TMPs ranges from 4559 × 10{sup −8} to 23,661 × 10{sup −8} m{sup 3} kg{sup −1} (on average 13,637 × 10{sup −8} m{sup 3} kg{sup −1}). Thermomagnetic and bulk X-ray diffraction analyses indicate that main magnetic minerals of TMPs are magnetite (Fe{sub 3}O{sub 4}) and hematite (α-Fe{sub 2}O{sub 3}). The morphology of TMPs observed by SEM includes three shape types: spherule, irregular-shaped, and aggregate particles. The size of spherical TMPs ranges from 30 to about 200 μm, with the largest percentage of 30–50 μm. Synchrotron–radiation-based microprobe (μ-XRF and μ-XRD) indicates that TMPs are enriched with heavy metals Pb, Cd, Zn, Cu, and Cr, which are incorporated into lattice or adsorbed on the surface of magnetite/hematite. The content of TMPs significantly relates with the Tomlinson Pollution Load Index (PLI) (R{sup 2} = 0.467), suggesting that it can be used as proxy indicator of degree of heavy metal contamination in urban soils. The magnetic properties, microstructure and mineralogical phases of TMPs can serve as the identification of pollution sources in urban soils. - Graphical

  11. Magnetic manipulation of actin orientation, polymerization, and gliding on myosin using superparamagnetic iron oxide particles.

    Science.gov (United States)

    Chen, Yun; Guzik, Stephanie; Sumner, James P; Moreland, John; Koretsky, Alan P

    2011-02-11

    The actin cytoskeleton controls cell shape, motility, as well as intracellular molecular trafficking. The ability to remotely manipulate actin is therefore highly desirable as a tool to probe and manipulate biological processes at the molecular level. We demonstrate actin manipulation by labeling actin filaments with superparamagnetic iron oxide particles (IOPs) and applying a uniform magnetic field to affect actin orientation, polymerization and gliding on myosin. We show for the first time magnetic manipulation of magnetizable actin filaments at the molecular level while gliding on a bed of myosin molecules and during polymerization. A model for the magnetic alignment and guiding mechanism is proposed based on the torque from the induced molecular anisotropy due to interactions between neighboring IOPs distributed along magnetically labeled actin molecules.

  12. A simulation study on image reconstruction in magnetic particle imaging with field-free-line encoding

    CERN Document Server

    Murase, Kenya

    2016-01-01

    The purpose of this study was to present image reconstruction methods for magnetic particle imaging (MPI) with a field-free-line (FFL) encoding scheme and to propose the use of the maximum likelihood-expectation maximization (ML-EM) algorithm for improving the image quality of MPI. The feasibility of these methods was investigated by computer simulations, in which the projection data were generated by summing up the Fourier harmonics obtained from the MPI signals based on the Langevin function. Images were reconstructed from the generated projection data using the filtered backprojection (FBP) method and the ML-EM algorithm. The effects of the gradient of selection magnetic field (SMF), the strength of drive magnetic field (DMF), the diameter of magnetic nanoparticles (MNPs), and the number of projection data on the image quality of the reconstructed images were investigated. The spatial resolution of the reconstructed images became better with increasing gradient of SMF and with increasing diameter of MNPs u...

  13. Particle-in-cell Simulations of Global Relativistic Jets with Helical Magnetic Fields

    CERN Document Server

    Duţan, Ioana; Mizuno, Yosuke; Niemiec, Jacek; Kobzar, Oleh; Pohl, Martin; Gómez, Jose L; Pe'er, Asaf; Frederiksen, Jacob T; Nordlund, Åke; Meli, Athina; Sol, Helene; Hardee, Philip E; Hartmann, Dieter H

    2016-01-01

    We study the interaction of relativistic jets with their environment, using 3-dimensional relativistic particle-in-cell simulations for two cases of jet composition: (i) electron-proton ($e^{-}-p^{+}$) and (ii) electron-positron ($e^{\\pm}$) plasmas containing helical magnetic fields. We have performed simulations of "global" jets containing helical magnetic fields in order to examine how helical magnetic fields affect kinetic instabilities such as the Weibel instability, the kinetic Kelvin-Helmholtz instability and the Mushroom instability. We have found that these kinetic instabilities are suppressed and new types of instabilities can grow. For the $e^{-}-p^{+}$ jet, a recollimation-like instability occurs and jet electrons are strongly perturbed, whereas for the $e^{\\pm}$ jet, a recollimation-like instability occurs at early times followed by kinetic instability and the general structure is similar to a simulation without a helical magnetic field. We plan to perform further simulations using much larger sys...

  14. Nano-magnetic particles used in biomedicine: core and coating materials.

    Science.gov (United States)

    Karimi, Z; Karimi, L; Shokrollahi, H

    2013-07-01

    Magnetic nanoparticles for medical applications have been developed by many researchers. Separation, immunoassay, drug delivery, magnetic resonance imaging and hyperthermia are enhanced by the use of suitable magnetic nanoparticles and coating materials in the form of ferrofluids. Due to their low biocompatibility and low dispersion in water solutions, nanoparticles that are used for biomedical applications require surface treatment. Various kinds of coating materials including organic materials (polymers), inorganic metals (gold, platinum) or metal oxides (aluminum oxide, cobalt oxide) have been attracted during the last few years. Based on the recent advances and the importance of nanomedicine in human life, this paper attempts to give a brief summary on the different ferrite nano-magnetic particles and coatings used in nanomedicine.

  15. Magnetic property and microstructure of single crystalline Nd2Fe14B ultrafine particles ball milled from HDDR powders

    Energy Technology Data Exchange (ETDEWEB)

    Li, WF; Hu, XC; Cui, BZ; Yang, JB; Han, JZ; Hadjipanayis, GC

    2013-08-01

    In this work we report the microstructure and magnetic property of single crystalline Nd2Fe14B ultrafine particles ball milled from HDDR Nd-Fe-B alloys. The average size of the particles is 283 nm, and TEM observation reveals that these particles are single crystalline. The coercivity of these particles is 6.0 kOe, which is much higher than that of the particles ball milled from sintered and hot pressed Nd-Fe-B magnets. Micromagnetic analysis shows that the coercivity degradation is caused by surface damage during ball milling. (C) 2013 Elsevier B.V. All rights reserved.

  16. High gradient magnetic filtration of cupric oxide and fly ash particles

    Energy Technology Data Exchange (ETDEWEB)

    Lua, A.C. [Nanyang Technological University (Singapore). School of Mechanical and Production Engineering

    1996-12-31

    High gradient magnetic filtration (HGMF) tests have been carried out on cupric oxide particles and power plant fly ash which were dispersed in air streams. An experimental test rig was set up to conduct these tests. Results showed that for cupric oxide particles, filtration efficiencies of up to 95% were obtained for submicron sizes with dust loadings of up to 0.36 time the matrix volume. For fly ash, filtration efficiencies of up to 65% were obtained for submicron particles. However, all particle sizes showed progressive deterioration in efficiencies with loading. At the end of the test, the matrix had collected 0.52 times its own mass of fly ash. 2 refs., 7 figs.

  17. Compact dielectric particles as a building block for low-loss magnetic metamaterials.

    Science.gov (United States)

    Popa, Bogdan-Ioan; Cummer, Steven A

    2008-05-23

    We characterize experimentally a compact dielectric particle that can be used to design very low-loss artificial electromagnetic materials (metamaterials). Focusing on magnetic media, we show that the particle can behave almost identically to the well-known split-ring resonators (SRRs) widely used in present designs, without suffering from the Ohmic losses that can limit the applicability of SRRs especially at high frequencies. We experimentally compare qualitatively and quantitatively the dielectric particle with a typical split-ring resonator of the same size built on a low-loss dielectric substrate and show that at GHz frequencies the quality factor of the dielectric particle is more than 3 times bigger than that of its metallic counterpart. Low-loss and simple geometry are significant advantages compared to conventional metal SRRs.

  18. Multi-step process for concentrating magnetic particles in waste sludges

    Science.gov (United States)

    Watson, John L.

    1990-01-01

    This invention involves a multi-step, multi-force process for dewatering sludges which have high concentrations of magnetic particles, such as waste sludges generated during steelmaking. This series of processing steps involves (1) mixing a chemical flocculating agent with the sludge; (2) allowing the particles to aggregate under non-turbulent conditions; (3) subjecting the mixture to a magnetic field which will pull the magnetic aggregates in a selected direction, causing them to form a compacted sludge; (4) preferably, decanting the clarified liquid from the compacted sludge; and (5) using filtration to convert the compacted sludge into a cake having a very high solids content. Steps 2 and 3 should be performed simultaneously. This reduces the treatment time and increases the extent of flocculation and the effectiveness of the process. As partially formed aggregates with active flocculating groups are pulled through the mixture by the magnetic field, they will contact other particles and form larger aggregates. This process can increase the solids concentration of steelmaking sludges in an efficient and economic manner, thereby accomplishing either of two goals: (a) it can convert hazardous wastes into economic resources for recycling as furnace feed material, or (b) it can dramatically reduce the volume of waste material which must be disposed.

  19. Functional expression of an scFv on bacterial magnetic particles by in vitro docking

    Energy Technology Data Exchange (ETDEWEB)

    Sugamata, Yasuhiro; Tanaka, Tsuyoshi; Matsunaga, Tadashi; Yoshino, Tomoko, E-mail: y-tomoko@cc.tuat.ac.jp

    2014-02-28

    Highlights: • We present a novel expression system called “in vitro docking” on bacterial magnetic particles. • An scFv–Fc was functionally expressed on bacterial magnetic