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Applied Magnetic Field (applied + magnetic_field)
Selected AbstractsEmission Intensity Enhancement of DC Arc Plasma Induced by External Oscillating Magnetic FieldCONTRIBUTIONS TO PLASMA PHYSICS, Issue 10 2007M. M. Stoiljkovi Abstract Direct current (dc) arc plasma with continuous aerosol supply was coupled with an external oscillatingmagnetic field of a few tens of mT and a frequency of up to 1 kHz. Such configuration was used to alter the plasma-related radiative properties. The magnetic field was oriented perpendicularly to the electric field in the plasma and forced the arc column to oscillate as a whole with respect to the surrounding atmosphere. The magnitude of the appliedmagnetic.eld controls the amplitude of the oscillatory motion. Several parameters that can contribute to the radiative properties of the plasma were investigated (arc current, composition of aerosol introduced into the plasma, amplitude and frequency of the magnetic field applied). Spectral emission from different zones of the plasma column was measured by optical emission spectroscopy (OES). In comparison to steady-state plasma, the applied magnetic field induces an intensity enhancement of emission of the most analytes considered. The intensity enhancement is strongly affected by the amplitude and frequency of plasma column oscillations, i.e. by plasma column velocity. Also, intensity enhancement depends on the plasma zone observed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Thermal and EPR investigations of thallium gallium disulphide single crystalCRYSTAL RESEARCH AND TECHNOLOGY, Issue 7 2009M. Acikgoz Abstract In this research, the results of the differential scanning calorimetry (DSC) and electron paramagnetic resonance (EPR) investigations of TlGaS2 single crystal are presented. Specific heat capacity (Cp) anomalies of layered TlGaS2 have been obtained by using a new DSC technique for such crystals. Remarkable heat capacity anomalies have been revealed at the temperatures of 137.7 K, 174.5 K and 238.5 K. It is found that the anomalies appear at maximum with a small deviation (by 3-4%) from the regular values, and Cp discontinuity amounted to approximately 5%. Additionally, EPR spectra of Fe doped TlGaS2 single crystals have been recorded at various temperatures down to 6 K for different orientations of the applied magnetic field. Transformations of present EPR spectra are not sufficient for the confirmation of structural phase transitions, in contrast to the cases in iso structural TlInS2 and TlGaSe2 compounds. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Recent developments in modelling of liquid phase electroepitaxy under applied magnetic fieldCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4-5 2005S. Dost Abstract Growth of single crystals under magnetic field is of interest for suppressing the adverse effect of natural convection and for better mixing in the liquid solution, which are the favorable conditions for prolonged growth and high quality crystals. In this short review article, recent developments in the modelling of electroepitaxy under magnetic field are presented. An application is given for the liquid phase electroepitaxial growth of GaAs bulk single crystals under a static magnetic field. Experimental results, that have shown that the growth rate under an applied static magnetic field is proportional to the applied magnetic field, and increases with the field intensity level, are predicted from the present model. The model also predicts growth interface shapes accurately. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Generation of Monodisperse Inorganic,Organic Janus Microspheres in a Microfluidic DeviceADVANCED FUNCTIONAL MATERIALS, Issue 10 2009Naveen Prasad Abstract This study presents a simple synthetic approach for the in situ preparation of monodisperse hybrid Janus microspheres (HJM) having organic and inorganic parts in a PDMS-based microfluidic device. Based on the mechanism of shear-force-driven break-off, merged droplets of two photocurable oligomer solutions having distinctive properties are generated into an immiscible continuous phase. Functionalized perfluoropolyether (PFPE) as the organic phase and hydrolytic allylhydridopolycarbosilane (AHPCS) as the inorganic phase are used for the generation in aqueous medium of HJM with well-defined morphology and high monodispersity (average diameter of 162,µm and a 3.5% coefficient of variation). The size and shape of the HJM is controlled by varying the flow rate of the disperse and continuous phases. The HJM have two distinctive regions: a hydrophobic hemisphere (PFPE) having a smooth surface and a relatively hydrophilic region (AHPCS) with a rough, porous surface. In addition, pyrolysis and subsequent oxidation of these HJM convert them into SiC-based ceramic hemispheres through the removal of the organic portion and etching off the silica shell. The selective incorporation of magnetic nanoparticles into the inorganic part shows the feasibility of the forced assembly of HJM in an applied magnetic field. [source] The reliability of emplacement temperature estimates using palaeomagnetic methods: a case study from Santorini, GreeceGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2000Leon Bardot The mode of origin of volcaniclastic deposits can be difficult to determine from field constraints, and the palaeomagnetic technique of emplacement temperature (Te) determination provides a powerful discriminatory test for primary volcanic origin. This technique requires that the low-blocking-temperature (Tb) component of remanence in the direction of the Earth's field in inherited lithic clasts is of thermal origin and was acquired during transport and cooling in a hot pyroclastic flow; otherwise, the Te determination may be inaccurate. If the low- Tb component is not of thermal origin it may be a viscous remanent magnetization (VRM) or a chemical remanent magnetization (CRM). The acquisition of a VRM depends on the duration of exposure to an applied magnetic field, and thus the laboratory unblocking temperature (Tub) of a VRM of a certain age imposes a minimum Te that can be determined for that deposit. Palaeointensity experiments were carried out to assess the magnetic origin (pTRM, CRM, or a combination of both) of the low- Tb component in a number of samples from pyroclastic deposits from Santorini, Greece. Seven of the 24 samples used in these experiments passed the stringent tests for reliable palaointensity determination. These values demonstrated, for six of the samples, that the low- Tb component was of thermal origin and therefore that the estimate of Te was valid. In the other 17 samples, valuable information was gained about the characteristics of the magnetic alteration that occurred during the palaeointensity experiments, allowing assessment of the reliability of Te estimates in these cases. These cases showed that if a CRM is present it has a direction parallel to the applied field, and not parallel to the direction of the parent grain. They also show that, even if a CRM is present, it does not necessarily affect the estimate of Te. Two samples used in these experiments displayed curvature between their two components of magnetization. Data from this study indicate that the curvature in these vector plots is probably due to the presence of MD grains and not CRM, although CRM is not ruled out as the cause of curvature in other samples with two vector components. [source] Magnetic Field-Induced Phase Transformation in NiMnCoIn Magnetic Shape-Memory Alloys,A New Actuation Mechanism with Large Work OutputADVANCED FUNCTIONAL MATERIALS, Issue 7 2009Haluk E. Karaca Abstract Magnetic shape memory alloys (MSMAs) have recently been developed into a new class of functional materials that are capable of magnetic-field-induced actuation, mechanical sensing, magnetic refrigeration, and energy harvesting. In the present work, the magnetic &!hyphen;field-induced martensitic phase transformation (FIPT) in Ni45Mn36.5Co5In13.5 MSMA single crystals is characterized as a new actuation mechanism with potential to result in ultra-high actuation work outputs. The effects of the applied magnetic field on the transformation temperatures, magnetization, and superelastic response are investigated. The magnetic work output of NiMnCoIn alloys is determined to be more than 1,MJ m,3 per Tesla, which is one order of magnitude higher than that of the most well-known MSMAs, i.e., NiMnGa alloys. In addition, the work output of NiMnCoIn alloys is orientation independent, potentially surpassing the need for single crystals, and not limited by a saturation magnetic field, as opposed to NiMnGa MSMAs. Experimental and theoretical transformation strains and magnetostress levels are determined as a function of crystal orientation. It is found that [111]-oriented crystals can demonstrate a magnetostress level of 140,MPa T,1 with 1.2% axial strain under compression. These field-induced stress and strain levels are significantly higher than those from existing piezoelectric and magnetostrictive actuators. A thermodynamical framework is introduced to comprehend the magnetic energy contributions during FIPT. The present work reveals that the magnetic FIPT mechanism is promising for magnetic actuation applications and provides new opportunities for applications requiring high actuation work-outputs with relatively large actuation frequencies. One potential issue is the requirement for relatively high critical magnetic fields and field intervals (1.5,3,T) for the onset of FIPT and for reversible FIPT, respectively. [source] Design and Fabrication of Magnetically Functionalized Core/Shell Microspheres for Smart Drug DeliveryADVANCED FUNCTIONAL MATERIALS, Issue 2 2009Xiuqing Gong Abstract The fabrication of magnetically functionalized core/shell microspheres by using the microfluidic flow-focusing (MFF) approach is reported. The shell of each microsphere is embedded with magnetic nanoparticles, thereby enabling the microspheres to deform under an applied magnetic field. By encapsulating a drug, for example, aspirin, inside the microspheres, the drug release of the microspheres is enhanced under the compression,extension oscillations that are induced by an AC magnetic field. This active pumping mode of drug release can be controlled by varying the frequency and magnitude of the applied magnetic field as well as the time profile of the magnetic field. UV absorption measurements of cumulative aspirin release are carried out to determine the influence of these factors. The drug release behavior is found to be significantly different depending on whether the applied field varies sinusoidally or in a step-function manner with time. [source] Cover Picture: Synthesis of Gadolinium-Labeled Shell-Crosslinked Nanoparticles for Magnetic Resonance Imaging Applications (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 8 2005Mater. Abstract Robust, amphiphilic core,shell nanoparticles that are selectively labeled with gadolinium in the hydrophilic and water-swollen shell layer are depicted in the cover picture. These well-defined nanostructured materials exhibit high relaxivity, a large loading capacity, and are based upon a biocompatible platform for ultimate function in magnetic resonance imaging (MRI) applications, as reported by Wooley and co-workers on p.,1248. Shell-crosslinked knedel-like nanoparticles (SCKs; "knedel" is a Polish term for dumplings) were derivatized with gadolinium chelates and studied as robust magnetic-resonance-imaging-active structures with hydrodynamic diameters of 40,±,3,nm. SCKs possessing an amphiphilic core,shell morphology were produced from the aqueous assembly of diblock copolymers of poly-(acrylic acid) (PAA) and poly(methyl acrylate) (PMA), PAA52,b,PMA128, and subsequent covalent crosslinking by amidation upon reaction with 2,2,-(ethylenedioxy)bis(ethylamine) throughout the shell layer. The properties of these materials, including non-toxicity towards mammalian cells, non-immunogenicity within mice, and capability for polyvalent targeting, make them ideal candidates for utilization within biological systems. The synthesis of SCKs derivatized with GdIII and designed for potential use as a unique nanometer-scale contrast agent for MRI applications is described herein. Utilization of an amino-functionalized diethylenetriaminepentaacetic acid,Gd analogue allowed for direct covalent conjugation throughout the hydrophilic shell layer of the SCKs and served to increase the rotational correlation lifetime of the Gd. In addition, the highly hydrated nature of the shell layer in which the Gd was located allowed for rapid water exchange; thus, the resulting material demonstrated large ionic relaxivities (39,s,1,mM,1) in an applied magnetic field of 0.47,T at 40,°C and, as a result of the large loading capacity of the material, also demonstrated high molecular relaxivities (20,000,s,1,mM,1). [source] Control of Double-Vortex Domain Configurations in a Shape-Engineered Trilayer Nanomagnet SystemADVANCED MATERIALS, Issue 4 2010Lei Huang A shape-engineered trilayer ferromagnetic/non-magnetic/ferromagnetic nanostructure is lithographically fabricated to support four stable flux-closure domain configurations at remanence. Quantitative phase measurements using electron holography reveal the detailed magnetization reversal process and demonstrate how four domain states with distinct vortex chirality combinations can be controllably achieved by systematic manipulation of the applied magnetic field (see image). [source] Biomagnetic fluid flow in a 3D rectangular ductINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 12 2004E. E. Tzirtzilakis1 Abstract The laminar, incompressible, three-dimensional, fully developed viscous flow of a non-conducting biomagnetic fluid in a impermeable rectangular duct is numerically studied in the presence of an applied magnetic field. It is assumed that the magnetic field strength is sufficiently strong to saturate the biofluid and the magnetization is given as a function of the magnetic field intensity. The system of the partial differential equations, resulting after the introduction of appropriate non-dimensional variables, is solved applying an efficient numerical technique based on a pressure-linked pseudotransient method on a common grid. Results concerning the existence and the uniqueness of the solution, are also given. The obtained results, for different values for the parameters entering into the problem under consideration, show that the flow is appreciably influenced by the presence of the magnetic field. Copyright © 2004 John Wiley & Sons, Ltd. [source] Receptor-Mediated Self-Assembly of Multi-Component Magnetic Nanowires,ADVANCED MATERIALS, Issue 3 2004K. Salem The directed orientation of ferromagnetic nanowires tethered to spatially controlled regions of a surface is reported. The Figure is a light microscope image of 9,,m-long, two-segment Au/Ni nanowires with a biotinylated Au segment tethered to patterned avidin tracks. The aspect ratio of the nickel segments is ,,50, so the magnetic easy axis is parallel to the wire axis. The nanowires have rotated to be parallel to an applied magnetic field. [source] Magneto-dielectric properties of the Y3Fe5O12 and Gd3Fe5O12 dielectric ferrite resonator antennasMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2008P. B. A. Fechine Abstract The main objective of this work was to study the magnetic and dielectric properties of Y3Fe5O12 and Gd3Fe5O12 garnets resonator antennas obtained from a new procedure in the solid state ceramic technique. These ferrite resonator antennas (FRAs) had the ability to change their characteristics as a function of the applied magnetic field. The Y3Fe5O12 resonator was able to increase the antenna frequency range with application of external magnetic field. Some of the properties of dielectric resonator antennas (DRAs) can be actively controlled by using low-loss ferrite materials. When unbiased, these ferrite resonator antennas (FRAs) exhibit similar behavior to DRAs. However, when a DC magnetic bias is applied, the tensor nature of the ferrite permeability is invoked, and various parameters can be controlled electronically. We also studied the magnetic behavior of the antennas and did a numerical study of the gain and directivity of the ferrite resonator antennas. These results can be important to develop wideband third-generation (3G) cellular phones and other wireless products. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2852,2857, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23824 [source] Magnetic field-dependence study of the magnetocaloric properties of a superparamagnetic nanoparticle system: a Monte Carlo simulationPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2008D. Serantes Abstract The influence of the applied magnetic field on the magnetocaloric properties of a fine magnetic particle system has been studied using a Monte Carlo technique. By simulating zero field cooling (ZFC) curves under different strengths of the applied magnetic field, we have analyzed the variation of the entropy for temperatures above the maximum of the ZFC curves, where the process is reversible. The entropy curves have been observed to behave in a different fashion at low values of the magnetic field, where the peak only slightly shifts to higher temperatures with increasing fields. For larger fields, the peak rapidly shifts to higher temperatures, while the overall shape of the curve broadens over a wide temperature range. It is also observed that the blocking temperature as a function of the magnetic field shows the feature of a change from a bell-like shape to a monotonically decreasing function, resembling what is found experimentally for intermediate values of the sample concentration. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Microwave measurement uncertainty due to applied magnetic fieldPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2007S. Perero Abstract In recent years there has been a wide interest in the production and analysis of films and nanostructures of different types for their microwave properties up to the mm-wave range. In order to characterize the electromagnetic behavior of these devices new experimental techniques need to be developed and assessed. Typically the measurements involve the use of vector network analyzer, and require several calibration steps. In this paper, we present a summary of the calibration techniques and evaluate the uncertainties obtained under different conditions, with a particular focus on the effect of the applied magnetic field upon uncertainty. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Characteristic magnetic length-scales in Vitroperm , Combining Kerr microscopy and small-angle neutron scatteringPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 15 2004A. Grob Abstract We present a study of the magnetic-field dependence of the magnetic microstructure of the nanocrystalline soft magnet Vitroperm (Fe73Si16B7Nb3Cu1), which was treated so as to exhibit a macroscopic magnetic anisotropy. The samples were analysed using Kerr microscopy and small-angle neutron scattering (SANS). As the applied magnetic field is decreased starting from saturation, we find that two processes occur independently: the formation of a domain structure with the net magnetisation of the domains aligned along the macroscopic easy axis and the increase in magnitude of static, nanometer-scale fluctuations of the spin orientation. The domain structure observations from Kerr microscopy are in excellent agreement with the results of the SANS experiments. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Magnetic-field dependence of electrothermal conductivity in YBCOPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11 2008A. Mariño Abstract Experimental measurements of the electrothermal conductivity (P) near Tc, as a function of external magnetic field were carried out in undoped YBCO (123) superconducting samples. The electrothermal conductivity which relates electrical and thermal currents, depends on the applied magnetic field in high Tc materials, contrary to conventional low Tc superconductors where P is nearly independent of the magnetic field. The experimental P (B, T) data determined from resistivity and thermopower measurements were analyzed in terms of theoretical models and showed a behavior consistent with an order-parameter symmetry (OPS) of d -wave type. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Spin polarization of a non-magnetic high g-factor semiconductor at low magnetic fieldPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 12 2007J. Lee Abstract We have studied the spin polarization of HgCdTe by measuring Shubnikov-de Haas oscillations. The magnetic field have been applied in parallel and perpendicular to the current. Relatively long spin relaxation time was observed since only spin conserved transition is allowed by selection rules. The electronic spin is completely polarized when the applied magnetic field is larger than 0.5 Tesla, which can be easily generated by micromagnets deposited on the surface of the specimen. Thus, the spin-manipulation such as spin up/down junction can be realized with this semiconductor. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Thermal hysteresis of the phase-transition temperature of single-crystal GdB6PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2006M. Reiffers Abstract The phase transition of a single-crystal sample of GdB6, oriented along the ,111, axis using the temperature dependence of electrical resistivity , (T ), susceptibility , (T ) and heat capacity C (T ) under an applied magnetic field was studied. , (T ) has shown 2 anomalies , a sharp drop at TN1 = 15.4 K and a small maximum at TN2 = 9.1 K with thermal hysteresis effect. , (T ) shows the anomalies at both transition temperatures. C (T ) shows similar thermal hysteresis effect at TN2. The small maximum at TN2 decreases its position to lower temperatures with increasing magnetic field. The peak at TN1 is practically unaffected by an applied magnetic field up to 9 T. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Field-induced effects in the S = 1 two-dimensional Heisenberg antiferromagnetPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 10 2005M. E. Gouvêa Abstract We use the self-consistent harmonic approximation to study the spin S = 1 Heisenberg antiferromagnet on a two-dimensional lattice in a uniform applied magnetic field. The magnetic field destroys the ,,(3) symmetry and an XY -like behavior, with a Berezinskii,Kosterlitz,Thouless (BKT) transition, is expected. We obtain the field dependence of the transition temperature for fields varying in a wide range. There has been experimental evidence that, for low dimensional spin systems, a gap can be induced by the applied magnetic field. We also investigate the behavior of this field-induced gap. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Lattice Green function for electrons in magnetic fieldPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2003Maciej M. Ma Abstract The energy spectrum of electrons on a square lattice in an applied magnetic field composes the famous Hofstadter butterfly with a recursive internal subband structure. An effective method for calculating the Green function for such a system is proposed. The standard approach requires an explicit knowledge of the eigenstates and eigenenergies of the system; here we derive a Harper-like equation, that allows us to calculate the Green function for the lattice electrons in the field directly. The method is particularly useful in the weak-field regime, where the standard calculations are cumbersome. [source] Possible anomalous Hall effect of Be/Si pair delta-doped GaAs structuresPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2008J. P. Noh Abstract Beryllium/Silicon pair delta-doped GaAs structures grown by molecular-beam epitaxy exhibit Hall resistance which has highly nonlinear dependence on the applied magnetic field. The dependence of the occurrence of the nonlinear Hall resistance on the sample structure is investigated. A significantly large increase in the non-linearity and magnitude of the Hall resistance is observed from a sample structure whose buffer layer is grown under the low As flux and thick buffer layer condition. The non-linearity of the Hall resistance is found to depend on a single parameter B /T, where B and T are the magnetic field and temperature, respectively. From another sample structure in which an AlGaAs barrier with a single Be delta-doped layer is placed near the Be/Si pair delta-doped layer, a similar nonlinear Hall resistance is observed. On the basis of these results, it is suggested that the anomalous Hall effect results from interplay between itinerant holes in the valence band and localized spins in the delta-doped layer in these structures. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nuclear field effect on the spin dynamics of electron localized on a donor in a single quantum wellPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2008C. Testelin Abstract We use photoinduced Faraday rotation (PFR) in presence of an applied magnetic field to study the spin dynamics of localized electrons. The sample is a CdTe/CdMgTe quantum well (QW) of width 80 Å containing a layer of iodine donors at its center, with concentration 1011 cm,2. The spin polarization of donor-bound electrons is built via the optical polarization of donor-bound excitons, their hole spin relaxation, and their recombination. In a transverse (in-plane) magnetic field, PFR shows damped Larmor oscillations from which we deduce a 18 ns electron-spin decoherence time, and a transverse Landé factor of 1.29. In addition, for oblique optical incidence the electron-nuclei hyperfine interaction builds a nuclear spin polarization in presence of polarized electrons. This leads to the construction of an effective magnetic field, the Overhauser field, acting on the electronic spins. The Larmor frequency is then different for ,+ or ,, polarizations of the exciting light. The dependence of the phenomenon on the optical incidence allows the determination of the maximal Overhauser field, which is about 10 mT, at least two orders of magnitude weaker than for III-V semiconductors. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Overhauser shift in photoluminescence of excitons with fine structure from a single self-assembled InAlAs quantum dotPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2006T. Mukumoto Abstract We report optical pumpingof nuclear spinpolarizationinasingle self-assembledIn0.75Al0.25As/Al0.3Ga0.7As quantum dot where the exciton has a fine structure. Through the change of state mixing that is induced by the anisotropic exchange interaction and the applied magnetic field, the relationship between the magnitude of the Overhauser shift and the optically injected electron spin polarization is discussed. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Determination of the pinned vortex fraction in type-II superconductorsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2006A. Bouaaddi Abstract In this article we intend to study the pinned vortex fraction in a type II superconductors. The sample used is the YBa2Cu3O7-,. This fraction pinned is determined from the comparison of the experimental results and the theoretical results previously definite. In continuation one will study the variations of this fraction according to the temperature of the applied magnetic field and the electric current crossing the sample. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis and magnetic properties of novel polymeric complexes containing bithiazole ringsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 12 2007Weihong Lin Abstract A novel linear polymer (PFABT) containing bithiazole rings was synthesized by polycondensation of 2,2,-diamino-4,4,-bithiazole (DABT) and formaldehyde. The complexes of PFABT with two transition metal ions (Fe2+, Cu2+) were prepared for the first time. The polymer was determined through FT-IR, 1H-NMR and elemental analysis (EA), and the complexes were characterized by FT-IR. The magnetic behaviors of these complexes were measured as a function of magnetic field strength (0,50,kOe) at 4,K and as a function of temperature (4,300,K) under an applied magnetic field of 30,kOe. The results show that PFABT-Cu2+ is a ferromagnet while PFABT-Fe2+ is an anti-ferromagnet. Copyright © 2007 John Wiley & Sons, Ltd. [source] Relaxation dynamics of the rheological properties of ferrofluidsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2009Dmitry Borin We studied experimentally the shear stress relaxation of two different ferrofluids under the action of an external magnetic field by stepwise changes of shear rate. It has been found that ferrofluids able to form significant structures under the influence of an applied magnetic field show a slow relaxation phenomenon. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Magnetoresistance in dilute p-Si/SiGe in parallel and tilted magnetic fieldsANNALEN DER PHYSIK, Issue 12 2009I.L. Drichko Abstract We report the results of an experimental study of the magnetoresistance ,xx and ,xy in two samples of p-Si/SiGe with low carrier concentrations p = 8.2 × 1010 cm -2 and p = 2 × 1011 cm -2. The research was performed in the temperature range of 0.3,2 K and in the magnetic fields of up to 18 T, parallel or tilted with respect to the two-dimensional (2D) channel plane. The large in-plane magnetoresistance can be explained by the influence of the in-plane magnetic field on the orbital motion of the charge carriers in the quasi-2D system. The measurements of ,xx and ,xy in the tilted magnetic field showed that the anomaly in ,xx, observed at filling factor , = 3/2 is practically nonexistent in the conductivity ,xx. The anomaly in ,xx at , = 2 might be explained by overlapping of the levels with different spins 0 , and 1 , when the tilt angle of the applied magnetic field is changed. The dependence of g-factor g*(,)/g*(00) on the tilt angle , was determined. [source] Microstructural, thermal, and electrical properties of Bi1.7V0.3Sr2Ca2Cu3Ox glass-ceramic superconductorCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2004T. S. Kayed Abstract A glass-ceramic Bi1.7V0.3Sr2Ca2Cu3Ox superconductor was prepared by the melt-quenching method. The compound was characterized by scanning electron microscopy, x-ray diffraction, differential thermal analysis, current-voltage characteristics, transport resistance measurements, and Hall effect measurements. Two main phases (BSCCO 2212 and 2223) were observed in the x-ray data and the values of the lattice parameters quite agree with the known values for 2212 and 2223 phases. The glass transition temperature was found to be 426 °C while the activation energy for crystallization of glass has been found to be Ea = 370.5 kJ / mol. This result indicates that the substitution of vanadium increased the activation energy for the BSCCO system. An offset Tc of 80 K was measured and the onset Tc was 100 K. The Hall resistivity ,H was found to be almost field-independent at the normal state. A negative Hall coefficient was observed and no sign reversal of ,H or RH could be noticed. The mobility and carrier density at different temperatures in the range 140-300 K under different applied magnetic fields up to 1.4 T were also measured and the results are discussed. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] In vitro exposure apparatus for ELF magnetic fieldsBIOELECTROMAGNETICS, Issue 8 2004Jürgen Schuderer Abstract For in vitro studies on the effect of extremely low frequency (ELF) magnetic field exposures in different laboratories, a programmable, high precision exposure system enabling blinded exposures has been developed and fully characterized. It is based on two shielded 4 coil systems that fit inside a commercial incubator. The volume of uniform B field exposure with 1% field tolerance is 50% larger compared to a Merrit 4 coil system with the same coil volume. The uncertainties for the applied magnetic fields have been specified to be less than 4%. The computer controlled apparatus allows signal waveforms that are composed of several harmonics, blind protocols, monitoring of exposure and environmental conditions and the application of B fields up to 3.6 mT root-mean-square amplitude. Sources of artifacts have been characterized: sham isolation >43 dB, parasitic incident E fields <1 V/m, no recognizable temperature differences in the media for exposure or sham state, and vibrations of the mechanically decoupled dish holder <0.1 m/s2 (= 0.01 g), which is only twice the sham acceleration background level produced by the incubator and fan vibrations. Bioelectromagnetics 25:582,591, 2004. © 2004 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||