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Sample records for dependent magnetic susceptibility

  1. Temperature dependence of magnetic susceptibility in the vicinity of martensitic transformation in ferromagnetic shape memory alloys.

    Science.gov (United States)

    Zablotskii, V; Pérez-Landazábal, J I; Recarte, V; Gómez-Polo, C

    2010-08-11

    Temperature dependences of low-field quasistatic magnetic susceptibility in the vicinity of martensitic transitions in an NiFeGa alloy are studied both by experiment and analytically. Pronounced reversible jumps of the magnetic susceptibility were observed near the martensitic transition temperature. A general description of the temperature dependences of the susceptibility in ferromagnetic austenite and martensite phases and the susceptibility jump at the transition is suggested. As a result, the main factors governing the temperature dependences of the magnetic susceptibility in the magnetic shape memory alloys are revealed. The magnetic susceptibility jump value is found to be related to changes of: (i) magnetic anisotropy; (ii) magnetic domain wall geometrical constraints (those determined by the alignment and size of twin variants) and (iii) mean magnetic domain spacing.

  2. Magnetic field dependent polarizability and electric field dependent diamagnetic susceptibility of a donor in Si

    Science.gov (United States)

    Muthukrishnaveni, M.; Srinivasan, N.

    2016-09-01

    The polarizability and diamagnetic susceptibility values of a shallow donor in Si are computed. These values are obtained for the cases bar{E}allel bar{B} and bar{E} bot bar{B}. The anisotropy introduced by these perturbations are properly taken care of in the expressions derived for polarizability and magnetic susceptibility. Our results show that the numerical value of the contribution from electric field to diamagnetic susceptibility is several orders smaller than that of the magnetic field effect. Polarizability values are obtained in a magnetic field by two different methods. The polarizability values decrease as the intensity of magnetic field increases. Using the Clausius-Mossotti relation, the anisotropic values of the refractive indices for different magnetic fields are estimated.

  3. Universal logarithmic temperature dependence of magnetic susceptibility of one-dimensional electrons at critical values of magnetic field

    OpenAIRE

    Vekua, Temo

    2014-01-01

    We study the leading low temperature dependence of magnetic susceptibility of one-dimensional electrons with fixed total number of particles at the magnetic fields equal to zero temperature critical values where magnetic field induces commensurate-incommensurate quantum phase transitions. For free and repulsively interacting electrons there is only one such critical field corresponding to the transition to the fully polarized state. For attractively interacting electrons besides saturation fi...

  4. Universal linear-temperature dependence of static magnetic susceptibility in iron-pnictides

    OpenAIRE

    Zhang, Guang-Ming; Su, Yue-Hua; Lu, Zhong-Yi; Weng, Zheng-Yu; Lee, Dung-Hai; Xiang, Tao

    2008-01-01

    A universal linear-temperature dependence of the uniform magnetic susceptibility has been observed in the nonmagnetic normal state of iron-pnictides. This non-Pauli and non-Curie-Weiss-like paramagnetic behavior cannot be understood within a pure itinerant picture. We argue that it results from the existence of a wide antiferromagnetic fluctuation window in which the local spin-density-wave correlations exist but the global directional order has not been established yet.

  5. Frequency-dependent magnetic susceptibility of magnetite and cobalt ferrite nanoparticles embedded in PAA hydrogel.

    Science.gov (United States)

    van Berkum, Susanne; Dee, Joris T; Philipse, Albert P; Erné, Ben H

    2013-05-14

    Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking of the gel. Here, acrylic acid monomers are adsorbed onto ferrite nanoparticles, which subsequently participate in polymerization during synthesis of poly(acrylic acid)-based hydrogels (PAA). To demonstrate the fixation of the nanoparticles to the polymer, our original approach is to measure low-field AC magnetic susceptibility spectra in the 0.1 Hz to 1 MHz range. In the hydrogel, the magnetization dynamics of small iron oxide nanoparticles are comparable to those of the particles dispersed in a liquid, due to fast Néel relaxation inside the particles; this renders the ferrogel useful for chemical sensing at frequencies of several kHz. However, ferrogels holding thermally blocked iron oxide or cobalt ferrite nanoparticles show significant decrease of the magnetic susceptibility resulting from a frozen magnetic structure. This confirms that the nanoparticles are unable to rotate thermally inside the hydrogel, in agreement with their irreversible fixation to the polymer network.

  6. Frequency-Dependent Magnetic Susceptibility of Magnetite and Cobalt Ferrite Nanoparticles Embedded in PAA Hydrogel

    Directory of Open Access Journals (Sweden)

    Ben H. Erné

    2013-05-01

    Full Text Available Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking of the gel. Here, acrylic acid monomers are adsorbed onto ferrite nanoparticles, which subsequently participate in polymerization during synthesis of poly(acrylic acid-based hydrogels (PAA. To demonstrate the fixation of the nanoparticles to the polymer, our original approach is to measure low-field AC magnetic susceptibility spectra in the 0.1 Hz to 1 MHz range. In the hydrogel, the magnetization dynamics of small iron oxide nanoparticles are comparable to those of the particles dispersed in a liquid, due to fast Néel relaxation inside the particles; this renders the ferrogel useful for chemical sensing at frequencies of several kHz. However, ferrogels holding thermally blocked iron oxide or cobalt ferrite nanoparticles show significant decrease of the magnetic susceptibility resulting from a frozen magnetic structure. This confirms that the nanoparticles are unable to rotate thermally inside the hydrogel, in agreement with their irreversible fixation to the polymer network.

  7. Frequency-Dependent Magnetic Susceptibility of Magnetite and Cobalt Ferrite Nanoparticles Embedded in PAA Hydrogel

    Science.gov (United States)

    van Berkum, Susanne; Dee, Joris T.; Philipse, Albert P.; Erné, Ben H.

    2013-01-01

    Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking of the gel. Here, acrylic acid monomers are adsorbed onto ferrite nanoparticles, which subsequently participate in polymerization during synthesis of poly(acrylic acid)-based hydrogels (PAA). To demonstrate the fixation of the nanoparticles to the polymer, our original approach is to measure low-field AC magnetic susceptibility spectra in the 0.1 Hz to 1 MHz range. In the hydrogel, the magnetization dynamics of small iron oxide nanoparticles are comparable to those of the particles dispersed in a liquid, due to fast Néel relaxation inside the particles; this renders the ferrogel useful for chemical sensing at frequencies of several kHz. However, ferrogels holding thermally blocked iron oxide or cobalt ferrite nanoparticles show significant decrease of the magnetic susceptibility resulting from a frozen magnetic structure. This confirms that the nanoparticles are unable to rotate thermally inside the hydrogel, in agreement with their irreversible fixation to the polymer network. PMID:23673482

  8. Non-Universal temperature dependencies of the low frequency ac magnetic susceptibility in high Tc superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Di Gioacchino, D.; Celani, F.; Tripodi, P. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati; Testa, A.M. [Consiglio Nazionale per le Ricerche, Monterotondo, RM, (Italy). Istituto di Chimica dei Materiali; Pace, S. [INFM, Univ. Salerno, Salerno (Italy). Dept. of Physics

    1999-07-01

    The paper is organized as follows. In Sec. 2 the non-linear diffusion problem is formulated in terms of a partial differential equation, together with the parallel resistor model for the 1-5 characteristics. To study in some detail the effects of thermally activated processes in different cases, we have chosen different temperature functional dependencies for the pinning potential, U{sub p}(T), and the critical current density, J{sub c}(T), related to particular pinning models. Local magnetic field profiles, magnetization cycles and {chi}n (T) are discussed in Sec. 3. Moreover, a comparison of numerical results with available experimental data and analytical approximated predictions is also presented. Finally, Sec. 4 is devoted to summary and conclusions.

  9. Magnetic susceptibility properties of polluted soils

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An investigation of magnetic properties using magnetic susceptibility (X) and frequency-dependent susceptibility (Xfd) was conducted on representative modern pollutants, which include smelted slag dust, automobile exhaust dust and coal ash. Their magnetic susceptibility values are more than 500×10-8 m3/kg, and frequency-dependent susceptibility values less than 3%, indicating that ample ferrimagnetic and scanty superparamagnetic grains occurred in the studied pollutants. Similar to the artificially synthetic polluted soils, the industrially-polluted soils display a negative relationship between magnetic susceptibility and frequency-dependent susceptibility. However, the unpolluted soils, e.g. the Quaternary loess in the Chinese Loess Plateau, show a positive relationship between them. In this note, we propose a convenient and effective approach for identifying the polluted soils.

  10. Frequency-Dependent Magnetic Susceptibility of Magnetite and Cobalt Ferrite Nanoparticles Embedded in PAA Hydrogel

    NARCIS (Netherlands)

    van Berkum, S.; Dee, J.T.; Philipse, A.P.; Erné, B.H.

    2013-01-01

    Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking

  11. Frequency-Dependent Magnetic Susceptibility of Magnetite and Cobalt Ferrite Nanoparticles Embedded in PAA Hydrogel

    NARCIS (Netherlands)

    van Berkum, S.; Dee, J.T.; Philipse, A.P.; Erné, B.H.

    2013-01-01

    Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking o

  12. Materials with low DC magnetic susceptibility for sensitive magnetic measurements

    CERN Document Server

    Khatiwada, Rakshya; Kendrick, Rachel; Khosravi, Marjan; Peters, Michael; Smith, Erick; Snow, Mike

    2015-01-01

    Materials with very low DC magnetic susceptibility have many scientific applications. To our knowledge however, relatively little research has been conducted with the goal to produce a totally nonmagnetic material. This phrase in our case means after spatially averaging over macroscopic volumes, it possesses an average zero DC magnetic susceptibility. We report measurements of the DC magnetic susceptibility of three different types of nonmagnetic materials at room temperature: (I) solutions of paramagnetic salts and diamagnetic liquids, (II) liquid gallium-indium alloys and (III) pressed powder mixtures of tungsten and bismuth. The lowest measured magnetic susceptibility among these candidate materials is in the order of 10^-9 cgs volume susceptibility units, about two orders of magnitude smaller than distilled water. In all cases, the measured concentration dependence of the magnetic susceptibility is consistent with that expected for the weighted sum of the susceptibilities of the separate components within...

  13. Investigation of the ac magnetic field dependence of the first and the third harmonics of the ac susceptibility in a granular Bi-2223 sample

    Energy Technology Data Exchange (ETDEWEB)

    Ozogul, O. [Ankara University, Faculty of Science, Department of Physics, Tandogan, 06100 Ankara (Turkey)

    2005-07-01

    The field and temperature dependencies of the first and third harmonics of the ac magnetic susceptibilities of a granular Bi-2223 superconductor have been investigated. Model calculations have been performed on the basis of a theoretical model that incorporates collective creep concepts in a critical-state equation by considering the temperature-dependent effective volume fraction. The predictions of the model for the field and temperature dependencies of the first and third harmonics were found to be in good agreement with experimental data. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Anisotropies of field-dependent in-phase and out-of-phase magnetic susceptibilities of some pyrrhotite-bearing rocks

    Science.gov (United States)

    Hrouda, Frantisek; Chadima, Martin; Jezek, Josef

    2017-04-01

    Pyrrhotite shows strong and non-linear variations of both the in-phase and out-of-phase magnetic susceptibilities with magnetizing field unlike to magnetite and paramagnetic minerals whose susceptibility is field independent if measured in low fields. Consequently, the magnetic sub-fabric of pyrrhotite unaffected by magnetite/paramagnetics can be directly investigated either through the anisotropy of field-dependent in-phase susceptibility (hdAMS) or through the anisotropy of out-of-phase susceptibility (opAMS). If the driving fields used for the susceptibility measurement are really low, within the range of validity of the Rayleigh Law, both the field-dependent component of the hdAMS and the opAMS are represented by the field-independent second rank Rayleigh Tensor. The determination of the Rayleigh Tensor via hdAMS requires the AMS measurements in several fields within the Rayleigh Law range, while in the determination of the Rayleigh Tensor via opAMS the measurement in one field is sufficient. It should be noted that if the AMS is measured by the KLY5 Kappabridge, the opAMS is measured simultaneously with standard in-phase AMS (ipAMS) during one measuring process. The Rayleigh Tensors determined by the above two methods should be more or less identical provided that the opAMS of pyrrhotite is dominantly due to weak field hysteresis, virtually unaffected by electrical eddy currents or viscous relaxation. In a collection of various pyrrhotite-bearing rocks, both the hdAMS and opAMS were investigated using the KLY5 Kappabridge and the correlations between the Rayleigh Tensors determined by the above two methods were made in terms of the anisotropy degree, shape parameter, and the orientations of principal directions. Reasonable correlations were found indicating that the pyrrhotite opAMS is dominantly due to weak field hysteresis. As the opAMS is measured automatically and simultaneously with standard ipAMS, the advantage of the opAMS in the determination of the

  15. 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.

  16. New insights into the paleoclimatic interpretation of the temperature dependence of the magnetic susceptibility and magnetization of Mid-Late Pleistocene loess/palaeosols in Central Asia and the Chinese Loess Plateau

    Science.gov (United States)

    Zan, Jinbo; Fang, Xiaomin; Yan, Maodu; Li, Bingshuai

    2016-11-01

    The temperature dependence of magnetic susceptibility (χ-T curves) and magnetization (M-T curves) has been used as a routine rock magnetic tool to characterize the magnetic mineralogy and magnetic granulometry of Chinese loess/palaeosols. However, paleoclimatic interpretation of these thermomagnetic analyses remains controversial. In the present study, total organic carbon (TOC), thermomagnetic and low-temperature magnetic experiments on Mid-Late Pleistocene loess/palaeosols in Central Asia and the Chinese Loess Plateau (CLP) have been conducted. We found that the M (T) cooling curves at room temperature were mostly lower than the corresponding heating curves, whereas for the χ (T) analyses the cooling curves at room temperature were always much higher than the heating curves. Low-temperature magnetic measurements demonstrated that a large amount of superparamagnetic ferrimagnetic particles were produced during the thermal treatment and resulted in the aforementioned differences. This finding further indicated that the use of the M - T curves to estimate the relative content of maghemite in the loess/paleosols from the CLP was problematic. In addition, a positive correlation exists between the TOC and the frequency-dependent susceptibility (χFD) in the CLP, suggesting that stronger pedogenesis would result in the simultaneous increase in the content of both maghemite and organic matter. Consequently, the parameters △χ1 (representing the relative content of pedogenic maghemite), △χ2 ([χph-χ] +△χ1) and χph (related to the organic matter concentration), which can be calculated from the χ - T analyses, can potentially be used as new indicators of pedogenesis and paleoclimate in Central Asia and the CLP.

  17. New insights into the palaeoclimatic interpretation of the temperature dependence of the magnetic susceptibility and magnetization of Mid-Late Pleistocene loess/palaeosols in Central Asia and the Chinese Loess Plateau

    Science.gov (United States)

    Zan, Jinbo; Fang, Xiaomin; Yan, Maodu; Li, Bingshuai

    2017-02-01

    The temperature dependence of magnetic susceptibility (χ-T curves) and magnetization (M-T curves) has been used as a routine rock magnetic tool to characterize the magnetic mineralogy and magnetic granulometry of Chinese loess/palaeosols. However, palaeoclimatic interpretation of these thermomagnetic analyses remains controversial. In the present study, total organic carbon (TOC), thermomagnetic and low-temperature magnetic experiments on Mid-Late Pleistocene loess/palaeosols in Central Asia and the Chinese Loess Plateau (CLP) have been conducted. We found that the M (T) cooling curves at room temperature were mostly lower than the corresponding heating curves, whereas for the χ (T) analyses the cooling curves at room temperature were always much higher than the heating curves. Low-temperature magnetic measurements demonstrated that a large amount of superparamagnetic ferrimagnetic particles were produced during the thermal treatment and resulted in the aforementioned differences. This finding further indicated that the use of the M-T curves to estimate the relative content of maghemite in the loess/palaeosols from the CLP was problematic. In addition, a positive correlation exists between the TOC and the frequency-dependent susceptibility (χFD) in the CLP, suggesting that stronger pedogenesis would result in the simultaneous increase in the content of both maghemite and organic matter. Consequently, the parameters ▵χ1 (representing the relative content of pedogenic maghemite), ▵χ2 ([χph - χ] +▵χ1) and χph (related to the organic matter concentration), which can be calculated from the χ-T analyses, can potentially be used as new indicators of pedogenesis and palaeoclimate in Central Asia and the CLP.

  18. Accuracy of magnetic resonance based susceptibility measurements

    Science.gov (United States)

    Erdevig, Hannah E.; Russek, Stephen E.; Carnicka, Slavka; Stupic, Karl F.; Keenan, Kathryn E.

    2017-05-01

    Magnetic Resonance Imaging (MRI) is increasingly used to map the magnetic susceptibility of tissue to identify cerebral microbleeds associated with traumatic brain injury and pathological iron deposits associated with neurodegenerative diseases such as Parkinson's and Alzheimer's disease. Accurate measurements of susceptibility are important for determining oxygen and iron content in blood vessels and brain tissue for use in noninvasive clinical diagnosis and treatment assessments. Induced magnetic fields with amplitude on the order of 100 nT, can be detected using MRI phase images. The induced field distributions can then be inverted to obtain quantitative susceptibility maps. The focus of this research was to determine the accuracy of MRI-based susceptibility measurements using simple phantom geometries and to compare the susceptibility measurements with magnetometry measurements where SI-traceable standards are available. The susceptibilities of paramagnetic salt solutions in cylindrical containers were measured as a function of orientation relative to the static MRI field. The observed induced fields as a function of orientation of the cylinder were in good agreement with simple models. The MRI susceptibility measurements were compared with SQUID magnetometry using NIST-traceable standards. MRI can accurately measure relative magnetic susceptibilities while SQUID magnetometry measures absolute magnetic susceptibility. Given the accuracy of moment measurements of tissue mimicking samples, and the need to look at small differences in tissue properties, the use of existing NIST standard reference materials to calibrate MRI reference structures is problematic and better reference materials are required.

  19. Magnetic susceptibility of tetragonal titanium dioxide

    Science.gov (United States)

    Senftle, F.E.; Pankey, T.; Grant, F.A.

    1960-01-01

    Careful measurements have been made of the magnetic susceptibility of the rutile and anatase crystalline forms of titanium dioxide. The magnetic susceptibility of a single crystal of high-purity rutile was found to be (0.067??0.0015)??10-6 emu per gram, and was temperature-independent from 55??to 372??K. Difficulty was encountered in obtaining a good value of the magnetic susceptibility of anatase because of impurities. However, a value of 0.02??10-6 emu per gram was obtained as a maximum value for anatase powder. A discussion is given for the different values obtained for anatase and rutile. ?? 1960 The American Physical Society.

  20. Complex susceptibility measurements of a suspension of magnetic beads

    Energy Technology Data Exchange (ETDEWEB)

    Fannin, P.C. [Department of Electronic and Electrical Engineering, Trinity College, Dublin 2 (Ireland)]. E-mail: pfannin@tcd.ie; Mac Oireachtaigh, C. [Department of Electronic and Electrical Engineering, Trinity College, Dublin 2 (Ireland); Cohen-Tannoudji, L. [Laboratoire Colloides et Materiaux Divises, CNRS UMR7612, ESPCI, 10 Rue Vauquelin, F-75005 Paris (France); Bertrand, E. [Laboratoire Colloides et Materiaux Divises, CNRS UMR7612, ESPCI, 10 Rue Vauquelin, F-75005 Paris (France); Bibette, J. [Laboratoire Colloides et Materiaux Divises, CNRS UMR7612, ESPCI, 10 Rue Vauquelin, F-75005 Paris (France)

    2006-05-15

    Measurements of the frequency and field dependence of the complex magnetic susceptibility, {chi}{sub s}({omega},H)={chi}{sub s}{sup '}({omega},H)-i{chi}{sub s}{sup '}'({omega},H), of a suspension of magnetic beads in water over the frequency range 200Hz to 1MHz are presented. The magnetic polarizing field, H, is applied to the sample, first in a forward direction and then in a reverse direction and from a plot of the static susceptibility, {chi}{sub 0S}, against polarizing field H, the existence of a hysteresis effect is demonstrated.

  1. Magnetic Susceptibility of Wet vs. Dry Sediment and Mass Normalized vs. Volume Normalized Magnetic Susceptibility

    Science.gov (United States)

    Kletetschka, G.; Hruba, J.; Nabelek, L.

    2015-12-01

    The measurement of magnetic susceptibility in sediments represents a fast and non-destructive technique that can be used to deduce the concentration of magnetic minerals [1, 2]. Magnetic minerals change their magnetic properties with temperature [3]. Heating (during a fire, laboratory, with the purpose of manufacturing a product, etc.) can modify a number of sediment properties [4, 5]. Heat-induced sediment mineralogical changes may cause irreversible changes in the sediment mineral structure and composition, and they occur at a wide range of temperature [6]. We provided measurements of magnetic susceptibility on samples from the Stara Jimka (SJ) paleo lacustrine site in the Bohemian Forest using magnetic susceptibility meter MS-30. Sediment samples of approximately 0.2 cm thickness were weighed and put into plastic containers. First, measurements of magnetic susceptibility were taken on wet samples. Then the containers were put into the oven and sediment was dried at temperature of 110°C. After drying and cooling to room temperature, measurements of magnetic susceptibility were repeated. Dry samples were also weighed. Comparison of magnetic susceptibility of dry versus wet samples showed higher values of magnetic susceptibility of dry samples. This enhancement was probably caused during oven-drying, when constituents of sediment (mainly clays) underwent heat-induced changes. We also compared volume normalized values of magnetic susceptibility with mass normalized values. Mass normalized magnetic susceptibility was burdened by greater noise. References: [1] QUIJANO, L. et al. 2001. Magnetic Susceptibilty in Topsoils and Bulk Cores of Cultivated Calcisols. [2] DEARING, J. A. 1994. Environmental Magnetic Susceptibility. [3] HANESCH, M. and SCHOLGER, R. 2005. The Influence of Soil Type on the Magnetic Susceptibility Measured throughout Soil Profiles. [4] FARWIG, V. J. et al. 2004. The Effects of Heating on Mineral Magnetic Enhancement of Soils. [5] KLETETSCHKA, G

  2. Clay mineralogy and magnetic susceptibility of Oxisols in geomorphic surfaces

    Directory of Open Access Journals (Sweden)

    Livia Arantes Camargo

    2014-06-01

    Full Text Available Studies analyzing the variability of clay minerals and magnetic susceptibility provide data for the delineation of site-specific management areas since many of their attributes are important to agronomy and the environment. This study aimed to evaluate the spatial variability of clay minerals, magnetic susceptibility, adsorbed phosphorus and physical attributes in Oxisols of sandstones in different geomorphic surfaces. For that purpose, soil samples were collected every 25 m along a transect located within the area where the geomorphic surfaces were identified and mapped. The transect occupied the central portion of 500 ha, where it was also sampled for density purposes with one sample per six hectares. Soil samples were collected at a depth of 0.0-0.2 m. The results of the physical, chemical, mineralogical and magnetic susceptibility analyses were subjected to statistical and geostatistical analyses. The nature of the clay minerals and magnetic susceptibility was dependent on the variation of the soil parent material. High values of magnetic susceptibility were associated with the presence of maghemite and magnetite of coarse size. The spatial variability of crystallinity and the content of Fe oxides, as well as magnetic susceptibility, were dependent on the age of the geomorphic surfaces. The youngest surface had greater spatial variability of these attributes. The iron (goethite and hematite and aluminum (gibbsite oxides in the youngest geomorphic surface influenced the low values of soil density and high values of total pore volume, micropores and P adsorption. The characterization of the spatial variability of Fe oxides and susceptibility allowed for the delineation of homogeneous areas.

  3. The magnetic susceptibility of European agricultural soils

    Science.gov (United States)

    Fabian, K.; Reimann, C.

    2012-04-01

    The GEMAS (Geochemical mapping of agricultural soils) project, a cooperation project between EuroGeoSurveys and Eurometaux, aims at providing soil quality data for Europe. Samples of arable soil were taken during 2008 at an average density of 1 site/2500 km2 covering the member states of the European Union (except Malta and Romania) and several neighbouring countries (e.g., Norway, Serbia, Ukraine). While the primary aim of the GEMAS project is to produce REACH (Registration, Evaluation and Authorisation of CHemicals - EC, 2006) consistent soil geochemistry data at the continental scale, the data set is also optimally apt to provide the first continental scale overview of magnetic properties in European soils. Soil samples from the upper 20 cm were taken as composites from 5 sites spread over a ca. 100 m2 area in a large agricultural field (Ap-sample). The samples were air dried and sieved to pass a 2 mm nylon screen. Weight normalized magnetic susceptibility of these dried samples was measured using a Sapphire Instruments SI2B susceptibility meter with dynamic background removal. The here presented maps of magnetic susceptibility in relation to geochemical composition and geological structures for the first time allow to outline the large scale influence of tectonics and climate on magnetic mineral concentration in European soils. The data set also provides the background variability for regional studies aiming to relate magnetic susceptibility of soils to local contamination sources.

  4. Field-dependence of AC susceptibility in titanomagnetites

    Science.gov (United States)

    Jackson, M.; Moskowitz, B.; Rosenbaum, J.; Kissel, Catherie

    1998-01-01

    AC susceptibility measurements as a function of field amplitude Hac and of frequency show a strong field dependence for a set of synthetic titanomagnetites (Fe3-xTixO4) and for certain basalts from the SOH-1 Hawaiian drill hole and from Iceland. In-phase susceptibility is constant below fields of about 10-100 A/m, and then increases by as much as a factor of two as Hsc is increased to 2000 A/m. Both the initial field-independent susceptibilities and field-dependence of susceptibility are systematically related to composition: initial susceptibility is 3 SI for a single-crystal sphere of TMO (x = 0) and decreases with increasing titanium content; field-dependence is nearly zero for TM0 and increases systematically to a maximum near TM60 (x = 0.6). This field dependence can in some cases be mistaken for frequency dependence, and leaf to incorrect interpretations of magnetic grain size and composition when titanomagnetite is present.

  5. Anisotropy of the magnetic susceptibility of gallium

    Science.gov (United States)

    Pankey, T.

    1960-01-01

    The bulk magnetic susceptibilities of single gallium crystals and polycrystalline gallium spheres were measured at 25??C. The following anisotropic diamagnetic susceptibilities were found: a axis (-0.119??0. 001)??10-6 emu/g, b axis (-0.416??0.002)??10 -6 emu/g, and c axis (-0.229??0.001) emu/g. The susceptibility of the polycrystalline spheres, assumed to be the average value for the bulk susceptibility of gallium, was (-0.257??0.003)??10-6 emu/g at 25??C, and (-0.299??0.003)??10-6 emu/g at -196??C. The susceptibility of liquid gallium was (0.0031??0.001) ??10-6 emu/g at 30??C and 100??C. Rotational diagrams of the susceptibilities in the three orthogonal planes of the unit cell were not sinusoidal. The anisotropy in the single crystals was presumably caused by the partial overlap of Brillouin zone boundaries by the Fermi-energy surface. The large change in susceptibility associated with the change in state was attributed to the absence of effective mass influence in the liquid state. ?? 1960 The American Institute of Physics.

  6. Magnetic susceptibilities of cluster-hierarchical models

    Science.gov (United States)

    McKay, Susan R.; Berker, A. Nihat

    1984-02-01

    The exact magnetic susceptibilities of hierarchical models are calculated near and away from criticality, in both the ordered and disordered phases. The mechanism and phenomenology are discussed for models with susceptibilities that are physically sensible, e.g., nondivergent away from criticality. Such models are found based upon the Niemeijer-van Leeuwen cluster renormalization. A recursion-matrix method is presented for the renormalization-group evaluation of response functions. Diagonalization of this matrix at fixed points provides simple criteria for well-behaved densities and response functions.

  7. Anisotropy of magnetic susceptibility of rocks induced by experimental deformation

    Directory of Open Access Journals (Sweden)

    J. Zhou

    1997-06-01

    Full Text Available In the present paper, the influence of the rheological process on the Anisotropy of Magnetic Susceptibility (AMS of rocks is studied experimentally. The cylindrical samples of quartz-magnetite rock undergo a process under the confining stress of 300 MPa, temperature of 500-800 °C and strain rate of 5 ´ 10-5 - 1 ´ 10-4/s. The residual deformation after the above process ranges 9-42%, depending on the experimental condition. It is found that the magnetic susceptibilities and the shapes of magnetic grains in these samples are almost isotropic before deformation. After being deformed, these samples show certain amounts of anisotropy of magnetic susceptibility and the axes of maximum principal susceptibilities deviate from the original ones more or less. Furthermore, the grains become oblate-ellipsoidal and a certain preferred orientation occurs. The grain shape anisotropy seems to be the main reason for AMS formation. It appears that there is a limitation of the piezomagnetic theory in explaining some tectonomagnetic phenomena. The results obtained in this study imply that ductile deformation at high temperature and pressure in depth during a long time-process may result in another kind of response in rock magnetism, which could be a new mechanism of tectonomagnetic variation.

  8. Correlation of AC Loss Data from Magnetic Susceptibility Measurements with YBCO Film Quality (Postprint)

    Science.gov (United States)

    2012-02-01

    AFRL-RZ-WP-TP-2012-0100 CORRELATION OF AC LOSS DATA FROM MAGNETIC SUSCEPTIBILITY MEASUREMENTS WITH YBCO FILM QUALITY (POSTPRINT) Paul N...CORRELATION OF AC LOSS DATA FROM MAGNETIC SUSCEPTIBILITY MEASUREMENTS WITH YBCO FILM QUALITY (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT...spreading of the temperature-dependent ac susceptibility curves with increasing applied magnetic field, the quality of the YBCO film generally

  9. Magnetic Susceptibility in the Vertebral Column

    Science.gov (United States)

    Schick, F.; Nagele, T.; Lutz, O.; Pfeffer, K.; Giehl, J.

    1994-01-01

    A magnetic resonance method is described which provides good-quality field-mapping images of the spine, although the in vivo signals from red bone marrow of the vertebral bodies exhibit similar fractions of lipid and water protons with their chemical-shift difference of 3.4 ppm. The susceptibilities of bone marrow and intervertebral disks were examined in 20 cadaveric human spines, 9 healthy volunteers, and 9 patients with degenerative disk alterations. The influence of geometrical properties was studied in cylindrical spine phantoms of different size and contents with different susceptibility. The measurements reveal interindividual differences of the susceptibility of the intervertebral disks in healthy subjects. Three out of nine degenerated disks with low signal in T2-weighted spin-echo images showed irregularities of the field distribution within the nucleus pulposus.

  10. Calculation of nonlinear magnetic susceptibility tensors for a uniaxial antiferromagnet

    Science.gov (United States)

    Lim, Siew-Choo; Osman, Junaidah; Tilley, D. R.

    2000-11-01

    In this paper, we present a derivation of the nonlinear susceptibility tensors for a two-sublattice uniaxial antiferromagnet up to the third-order effects within the standard definition by which the rf magnetization m is defined as a power series expansion in the rf fields h with the susceptibility tensors χ(q) as the coefficients. The starting point is the standard set of torque equations of motion for this problem. A complete set of tensor elements is derived for the case of a single-frequency input wave. Within a circular polarization frame (pnz) expressions are given for the first-order susceptibility, second-harmonic generation, optical rectification, third-harmonic generation and intensity-dependent susceptibility. Some of the coefficients with representative resonance features in the far infrared are illustrated graphically and we conclude with a brief discussion of the implications of the resonance features arising from the calculations and their potential applications.

  11. 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.

  12. Nonlinear susceptibility magnitude imaging of magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ficko, Bradley W., E-mail: Bradley.W.Ficko@Dartmouth.edu; Giacometti, Paolo; Diamond, Solomon G.

    2015-03-15

    This study demonstrates a method for improving the resolution of susceptibility magnitude imaging (SMI) using spatial information that arises from the nonlinear magnetization characteristics of magnetic nanoparticles (mNPs). In this proof-of-concept study of nonlinear SMI, a pair of drive coils and several permanent magnets generate applied magnetic fields and a coil is used as a magnetic field sensor. Sinusoidal alternating current (AC) in the drive coils results in linear mNP magnetization responses at primary frequencies, and nonlinear responses at harmonic frequencies and intermodulation frequencies. The spatial information content of the nonlinear responses is evaluated by reconstructing tomographic images with sequentially increasing voxel counts using the combined linear and nonlinear data. Using the linear data alone it is not possible to accurately reconstruct more than 2 voxels with a pair of drive coils and a single sensor. However, nonlinear SMI is found to accurately reconstruct 12 voxels (R{sup 2}=0.99, CNR=84.9) using the same physical configuration. Several time-multiplexing methods are then explored to determine if additional spatial information can be obtained by varying the amplitude, phase and frequency of the applied magnetic fields from the two drive coils. Asynchronous phase modulation, amplitude modulation, intermodulation phase modulation, and frequency modulation all resulted in accurate reconstruction of 6 voxels (R{sup 2}>0.9) indicating that time multiplexing is a valid approach to further increase the resolution of nonlinear SMI. The spatial information content of nonlinear mNP responses and the potential for resolution enhancement with time multiplexing demonstrate the concept and advantages of nonlinear SMI. - Highlights: • Development of a nonlinear susceptibility magnitude imaging model • Demonstration of nonlinear SMI with primary and harmonic frequencies • Demonstration of nonlinear SMI with primary and intermodulation

  13. Nonlinear susceptibility magnitude imaging of magnetic nanoparticles

    Science.gov (United States)

    Ficko, Bradley W.; Giacometti, Paolo; Diamond, Solomon G.

    2015-03-01

    This study demonstrates a method for improving the resolution of susceptibility magnitude imaging (SMI) using spatial information that arises from the nonlinear magnetization characteristics of magnetic nanoparticles (mNPs). In this proof-of-concept study of nonlinear SMI, a pair of drive coils and several permanent magnets generate applied magnetic fields and a coil is used as a magnetic field sensor. Sinusoidal alternating current (AC) in the drive coils results in linear mNP magnetization responses at primary frequencies, and nonlinear responses at harmonic frequencies and intermodulation frequencies. The spatial information content of the nonlinear responses is evaluated by reconstructing tomographic images with sequentially increasing voxel counts using the combined linear and nonlinear data. Using the linear data alone it is not possible to accurately reconstruct more than 2 voxels with a pair of drive coils and a single sensor. However, nonlinear SMI is found to accurately reconstruct 12 voxels (R2=0.99, CNR=84.9) using the same physical configuration. Several time-multiplexing methods are then explored to determine if additional spatial information can be obtained by varying the amplitude, phase and frequency of the applied magnetic fields from the two drive coils. Asynchronous phase modulation, amplitude modulation, intermodulation phase modulation, and frequency modulation all resulted in accurate reconstruction of 6 voxels (R2>0.9) indicating that time multiplexing is a valid approach to further increase the resolution of nonlinear SMI. The spatial information content of nonlinear mNP responses and the potential for resolution enhancement with time multiplexing demonstrate the concept and advantages of nonlinear SMI.

  14. Quantification of entanglement from magnetic susceptibility for a Heisenberg spin 1/2 system

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Tanmoy; Singh, Harkirat; Das, Diptaranjan; Sen, Tamal K. [Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur Campus, PO BCKV Campus Main Office, Mohanpur – 741252, Nadia, West Bengal (India); Mitra, Chiranjib, E-mail: chiranjib@iiserkol.ac.in [Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur Campus, PO BCKV Campus Main Office, Mohanpur – 741252, Nadia, West Bengal (India)

    2012-10-01

    We report temperature and magnetic field dependent magnetization and quantification of entanglement from the experimental data for dichloro (thiazole) copper (II), a Heisenberg spin chain system. The plot of magnetic susceptibility vs. temperature indicates an infinite spin chain. Isothermal magnetization measurements (as functions of magnetic field) were performed at various temperatures below the antiferromagnetic (AFM) ordering, where the AFM correlations persist significantly. These magnetization curves are fitted to the Bonner–Fisher model. Magnetic susceptibility is used as an entanglement witness to quantify the amount of entanglement in the system. -- Highlights: ► Magnetic properties of a Heisenberg spin chain system are studied. ► Experimental data is fitted to theoretical models. ► Magnetic susceptibility is used as a macroscopic witness of entanglement. ► Entanglement is extracted from experimental data.

  15. Role of magnetic susceptibility weighted imaging in evaluation of ...

    African Journals Online (AJOL)

    Role of magnetic susceptibility weighted imaging in evaluation of brain lesions. ... Log in or Register to get access to full text downloads. ... SWI detects the signal loss created by disturbance of a homogeneous magnetic field; these ...

  16. Non-Magnetic Factors Affecting Magnetic Susceptibility of the Loess-Paleosol Sequences in the Chinese Loess Plateau

    Science.gov (United States)

    Wang, H.; Feng, Z.

    2009-12-01

    Several different proposals have been adopted to explain the linkage between the magnetic susceptibility of loess-paleosol sequences and the associated past climate. First, the intensity of dustfall controlled the variation in the susceptibility. Second, the degree of pedogenesis controlled the variation. A third proposal states that the susceptibility signal is a result of the competing processes between pedogenic enhancement and detrital inheritance. This paper examines the acceptability as the summer monsoon proxy from nonmagnetic perspectives. Several conclusions can be drawn from our data. First, clay translocation within the Last Interglacial paleosol S1 profiles must have moved some of the magnetic minerals downward so that the susceptibility reflects only the post-translocation distribution of the magnetic susceptibility-producing minerals. Second, the best-developed paleosol S1S3 (equivalent to MIS 5e) at most of the sections studied is not well expressed by the magnetic susceptibility because this paleosol developed in underlying coarse loess (L2) and coarse textures tend to lower the susceptibility. Third, carbonate concentration is negatively correlated with the magnetic susceptibility or suppresses the magnetic susceptibility peak when the susceptibility enhancement exceeds the carbonate dilution effect. It should be stressed that the susceptibility signal and its contributors in eolian sequences can be site- and time-dependent within the Chinese Loess Plateau. A stronger eolian component northwestward and a stronger pedogenic component southeastward are the general trends, but the trends can be complicated by those site- and time-dependent factors. Therefore, a more comprehensive model is needed to more precisely address the relationship between the paleoclimate and the proxy.

  17. Magnetic susceptibility, magnetization, magnetic moment and characterization of Carancas meteorite

    CERN Document Server

    Rosales, Domingo

    2015-01-01

    On September, 15th, 2007, in the community of Carancas (Puno, Peru) a stony meteorite formed a crater explosive type with a mean diameter of 13.5 m. some samples meteorite fragments were collected. The petrologic analysis performed corresponds to a meteorite ordinary chondrite H 4-5. In this paper we have analyzed the magnetic properties of a meteorite fragment with a proton magnetometer. Also in order to have a complete characterization of the Carancas meteorite and its crater, from several papers, articles and reports, we have made a compilation of the most important characteristics and properties of this meteorite.

  18. A partial susceptibility approach to analysing the magnetic properties of environmental materials: a case study

    Science.gov (United States)

    Xie, Shanju; Dearing, John A.; Bloemendal, Jan

    1999-09-01

    An approach to expressing the magnetic properties of environmental materials in terms of the contributions of the magnetic susceptibilities of specific magnetic components is reported. The approach links the partial susceptibilities of discrete particles, domains or mineral fractions with the concentration-dependent parameters by means of multiple linear regression methods. The case study, using the Liverpool street dust data set, demonstrates that the technique is able to model the contributions of the main magnetic components satisfactorily. Several factors may have a significant impact on the regression results. These include the validity of the linear proportional relationships between partial susceptibilities and the relevant concentration-dependent parameters, the adequacy of the variable selection procedure and the regression model, and the suitability of certain magnetic parameters.

  19. Magnetic susceptibility of the Xifeng section and its paleoclimate significance

    Institute of Scientific and Technical Information of China (English)

    SUN Yubing; CHEN Tianhu; XIE Qiaoqin

    2009-01-01

    Magnetic susceptibility (MS) is one of the most important indicators of the East-Asia summer monsoon. Presented in this study is a high resolution magnetic susceptibility record from the Xifeng section, which consists of Quaternary loess-paleosol sequence and Pliocene red clay. Variations in magnetic susceptibility are well correlated with the δ18O record in deep-sea sediments and the eolian flux of Greenland. The climatic evolution in the Xifeng section shows that since the Late Tertiary, the driving force of the East-Asia paleo-monsoon is correlated with solar radiation on a 10-ka time scale.

  20. Toward Modelling Topsoil Magnetic Susceptibility for Demining Activities

    Science.gov (United States)

    Hannam, J. A.; Dearing, J. A.

    2003-12-01

    The Landmine Monitor estimates that landmines cause up to 20,000 fatalities and casualties worldwide every year, in over 100 countries affected by landmine contamination. Although detection technologies have become more sophisticated, the metal detector still remains the most widely employed detection system in landmine affected regions. With increased use of minimum metal mines, the performance and sensitivity of metal detectors are increasingly challenged. In addition to mine constituents, depth of burial and orientation, soil properties significantly affect metal detection capabilities. Soils with high magnetic susceptibility, in particular those dominated by viscous components, interfere with the response signal in both frequency and time domain metal detection systems. Using Bosnia and Herzegovina (BiH) as a pilot region, we created an expert system to predict topsoil susceptibility from environmental information within a SOTER data base. Initially, the knowledge base is constructed from published relationships of environmental parameters and magnetic susceptibility and knowledge of experts in the field of soil magnetism. The knowledge base is underpinned by environmental conditions that are known to enhance or reduce magnetic susceptibility in topsoils. Where semi-quantitative data exists, transfer-functions are used to provide first approximations of susceptibility classes and offer a basis for a probability score for the susceptibility class. As a first approximation, susceptibility values are categorized into five continuous classes delimited by published magnetic susceptibility ranges in topsoils. The predicted susceptibility maps result in regional contrasts, delineated by the spatial scale of the environmental information. Further development of the model using a Baysean rule-based system with fuzzy boundaries is anticipated. Validation of the model is proposed using archived soil survey samples from BiH. In addition to providing essential data for

  1. Echo time-dependent quantitative susceptibility mapping contains information on tissue properties.

    Science.gov (United States)

    Sood, Surabhi; Urriola, Javier; Reutens, David; O'Brien, Kieran; Bollmann, Steffen; Barth, Markus; Vegh, Viktor

    2017-05-01

    Magnetic susceptibility is a physical property of matter that varies depending on chemical composition and abundance of different molecular species. Interest is growing in mapping of magnetic susceptibility in the human brain using magnetic resonance imaging techniques, but the influences affecting the mapped values are not fully understood. We performed quantitative susceptibility mapping on 7 Tesla (T) multiple echo time gradient recalled echo data and evaluated the trend in 10 regions of the human brain. Temporal plots of susceptibility were performed in the caudate, pallidum, putamen, thalamus, insula, red nucleus, substantia nigra, internal capsule, corpus callosum, and fornix. We implemented an existing three compartment signal model and used optimization to fit the experimental result to assess the influences that could be responsible for our findings. The temporal trend in susceptibility is different for different brain regions, and subsegmentation of specific regions suggests that differences are likely to be attributable to variations in tissue structure and composition. Using a signal model, we verified that a nonlinear temporal behavior in experimentally computed susceptibility within imaging voxels may be the result of the heterogeneous composition of tissue properties. Decomposition of voxel constituents into meaningful parameters may lead to informative measures that reflect changes in tissue microstructure. Magn Reson Med 77:1946-1958, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  2. Magnetic Susceptibilities as they appeared to me - An Amperian approach

    Energy Technology Data Exchange (ETDEWEB)

    Van den Bosch, A.

    2008-08-15

    Starting from scratch, the book narrates a systematic story of the basic ideas you need for understanding quasi static magnetic susceptibilities. The story leans on the authors 25 year experience measuring susceptibilities following the Faraday technique (related with solid state physics, radiation effects, materials and magneto chemistry). The base of magnetism, the current-current interaction, is the linkage between the topics treated. The number of mathematical equations are reduced to a minimum and can be skipped without losing the thread of the story. The story is positive towards the sound bases of magnetism. However, room is left for the interpretation of measuring data. As the word susceptibility covers different meanings, the story answers for different situations the question: what is susceptible to what for creating what?

  3. Probe imaging studies of magnetic susceptibility and permeability for sensitive characterisation of carbonate reservoir rocks

    Science.gov (United States)

    Ivakhnenko, Aleksandr; Bigaliyeva, Akmaral; Dubinin, Vladislav

    2016-04-01

    In this study were disclosed the main principals of identifying petrophysical properties of carbonate reservoirs such as porosity, permeability and magnetic susceptibility. While exploring and developing reservoir there are significant diversity of tasks that can be solved by appropriate knowledge of properties which are listed above. Behavior of fluid flow, distribution of hydrocarbons and other various industrial applications can be solved by measuring areal distribution of these petrophysical parameters. The results demonstrate how magnetic probe and hysteresis measurements correlate with petrophysical parameters in carbonate reservoirs. We made experimental measurements and theoretical calculations of how much magnetic susceptibility depends on the porosity of the rocks and analyzed data with graphics. In theoretical model of the carbonate rocks we considered calcite, dolomite, quartz and combinations of calcite and dolomite, calcite and Fe-dolomite, calcite and quartz, calcite and aragonite with increasing concentrations of the dolomite, Fe-dolomite, quartz and aragonite up to 50% with step of 5%. Here we defined dependence of magnetic susceptibility from the porosity: the higher porosity measurements, the less slope of magnetic susceptibility, consequently mass magnetization is higher for diamagnetic and lower for paramagnetic carbonate rocks, but in the both cases magnetic susceptibility tries to reach zero with increasing of the total porosity. Rock measurements demonstrate that reservoir zones of the low diamagnetic magnetic susceptibility are generally correlated with higher permeability and also porosity distribution. However for different carbonate reservoirs we establish different relationships depending on the complexity of their mineralogy and texture. Application of integral understanding in distribution of permeability, porosity and mineral content in heterogeneous carbonates represented by this approach can be useful tool for carbonate reservoir

  4. Identification of the vortex glass phase by harmonics of the AC magnetic susceptibility

    OpenAIRE

    Adesso, M G; Polichetti, M.; Pace, S.

    2005-01-01

    We compared the AC magnetic susceptibility behaviour for the vortex glass phase and for the creep phenomena with an inhomogeneous pinning potential. The temperature dependence of the harmonics of the susceptibility have been numerically simulated with these two models, and we studied them as a function of the frequency, in terms of Cole-Cole plots. From our analysis we show that it is possible to distinguish between the two different phases, because of their clear differences in the Cole-Cole...

  5. Magnetic susceptibility at high fields of Pb{sub 2}V{sub 3}O{sub 9}

    Energy Technology Data Exchange (ETDEWEB)

    Waki, T. [Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan)]. E-mail: twac@issp.u-tokyo.ac.jp; Tsujii, N. [National Institute for Materials Science, Sengen 1-2-1, Tsukuba 305-0047 (Japan); Itoh, Y. [Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Michioka, C. [Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Yoshimura, K. [Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Suzuki, O. [National Institute for Materials Science, Sengen 1-2-1, Tsukuba 305-0047 (Japan); Kitazawa, H. [National Institute for Materials Science, Sengen 1-2-1, Tsukuba 305-0047 (Japan); Kido, G. [National Institute for Materials Science, Sengen 1-2-1, Tsukuba 305-0047 (Japan)

    2007-08-01

    The temperature dependence of magnetic susceptibility was measured for the S=12 quasi one dimensional antiferromagnet Pb{sub 2}V{sub 3}O{sub 9} under the steady magnetic field up to {mu}{sub 0}H=30 T. This material has alternating exchange interaction and a spin-gap at zero magnetic field. An anomaly of magnetic susceptibility indicating the field-induced antiferromagnetic long-range order was observed in high magnetic fields. The Neel temperature at high fields is much lower than the calculated value based on the standard mean-field theory of field-induced magnetic order.

  6. Ac magnetic susceptibility study of in vivo nanoparticle biodistribution

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, L; Veintemillas-Verdaguer, S; Serna, C J; Morales, M P [Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC, Sor Juana Ines de la Cruz 3, Cantoblanco 28049, Madrid (Spain); MejIas, R; Barber, D F [Centro Nacional de BiotecnologIa, CNB-CSIC, Darwin 3, Cantoblanco 28049, Madrid (Spain); Lazaro, F J, E-mail: lucia@icmm.csic.es [Departamento de Ciencia y Tecnologia de Materiales y Fluidos, Universidad de Zaragoza, Maria de Luna 3, 50018, Zaragoza (Spain)

    2011-06-29

    We analysed magnetic nanoparticle biodistribution, before and after cytokine conjugation, in a mouse model by ac susceptibility measurements of the corresponding resected tissues. Mice received repeated intravenous injections of nanoparticle suspension for two weeks and they were euthanized 1 h after the last injection. In general, only 10% of the total injected nanoparticles after multiple exposures were found in tissues. The rest of the particles may probably be metabolized or excreted by the organism. Our findings indicate that the adsorption of interferon to DMSA-coated magnetic nanoparticles changes their biodistribution, reducing the presence of nanoparticles in lungs and therefore their possible toxicity. The specific targeting of the particles to tumour tissues by the use of an external magnetic field has also been studied. Magnetic nanoparticles were observed by transmission electron microscopy in the targeted tissue and quantified by ac magnetic susceptibility.

  7. Magnetic susceptibility and exchange coupling in the mineral ardennite

    Science.gov (United States)

    Thorpe, A.N.; Senftle, F.E.; Donnay, G.

    1969-01-01

    Ardennite, a rare silicate mineral, contains about 19 wt.% manganese. Some of the manganese atoms are in positions which are close enough to allow negative exchange and hence a reduction of the total magnetic susceptibility. It is shown that the susceptibility can be accounted for approximately by the treatment of Earnshaw and Lewis (1958) for S = 5 2 and a Hamiltonian H = -2g??Hb-2JS1??S2. ?? 1969.

  8. Magnetic susceptibility of Inconel alloys 718, 625, and 600 at cryogenic temperatures

    Science.gov (United States)

    Goldberg, Ira B.; Mitchell, Michael R.; Murphy, Allan R.; Goldfarb, Ronald B.; Loughran, Robert J.

    1990-01-01

    After a hydrogen fuel bleed valve problem on the Discovery Space Shuttle was traced to the strong magnetization of Inconel 718 in the armature of the linear variable differential transformer near liquid hydrogen temperatures, the ac magnetic susceptibility of three samples of Inconel 718 of slightly different compositions, one sample of Inconel 625, and on sample of Inconel 600 were measured as a function of temperature. Inconel 718 alloys are found to exhibit a spin glass state below 16 K. Inconel 600 exhibits three different magnetic phases, the lowest-temperature state (below 6 K) being somewhat similar to that of Inconel 718. The magnetic states of the Inconel alloys and their magnetic susceptibilities appear to be strongly dependent on the exact composition of the alloy.

  9. Geostatistical Microscale Study of Magnetic Susceptibility in Soil Profile and Magnetic Indicators of Potential Soil Pollution.

    Science.gov (United States)

    Zawadzki, Jarosław; Fabijańczyk, Piotr; Magiera, Tadeusz; Rachwał, Marzena

    Directional variograms, along the soil profile, can be useful and precise tool that can be used to increase the precision of the assessment of soil pollution. The detail analysis of spatial variability in the soil profile can be also an important part of the standardization of soil magnetometry as a screening method for an assessment of soil pollution related to the dust deposition. The goal of this study was to investigate the correlation between basic parameters of spatial correlations of magnetic susceptibility in the soil profile, such as a range of correlation and a sill, and selected magnetometric indicators of soil pollution. Magnetic indicators were an area under the curve of magnetic susceptibility versus a depth in the soil profile, values of magnetic susceptibility at depths ranging from 1 to 10 cm, and maximum and background values of magnetic susceptibility in the soil profile. These indicators were previously analyzed in the literature. The results showed that a range of correlation of magnetic susceptibility was significantly correlated with magnetic susceptibility measured at depths 1, 2, and 3 cm. It suggests that a range of correlation is a good measure of pollutants' dispersion in the soil profile. The sill of the variogram of magnetic susceptibility was found to be significantly correlated with the area under the curve of plot of magnetic susceptibility that is related to the soil pollution. In consequence, the parameters of microscale spatial variability of magnetic susceptibility in s soil profile are important measures that take into consideration the spatial aspect of s soil pollution.

  10. Magnetic irreversibility in granular superconductors: ac susceptibility study

    Energy Technology Data Exchange (ETDEWEB)

    Perez, F.; Obradors, X.; Fontcuberta, J. (ICMAB, CSIC, Bellaterra, Barcelona (Spain)); Vallet, M.; Gonzalez-Calbet, J. (Lab. Magnetismo Aplicado, RENFE-U.C. Madrid, Las Matas (Spain))

    1991-12-01

    Ac susceptibility measurements of a ceramic weak-coupled superconductor in very low ac fields (2mG, 111Hz) are reported. We present evidence for the observation of the magnetic irreversibility following a ZFC-FC thermal cycling by means of ac susceptibilty measurements. It is shown that this technique also reflect local magnetic field effects in granular superconductors, as previously suggested in microwave surface resistance and I-V characteristics. (orig.).

  11. Assessing magnetic nanoparticle aggregation in polymer melts by dynamic magnetic susceptibility measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sierra-Bermúdez, Sergio [Department of Chemical Engineering, University of Puerto Rico, P.O. Box 9000 Mayaguez, PR 00681 PR (United States); Maldonado-Camargo, Lorena P. [Department of Chemical Engineering, University of Florida, 1006 Center Drive, Gainesville, FL 32603 (United States); Orange, François [Department of Physics and Nanoscopy Facility, College of Natural Sciences, University of Puerto Rico, PO Box 70377, San Juan, PR 00936-8377 (United States); Guinel, Maxime J.-F. [Department of Physics and Nanoscopy Facility, College of Natural Sciences, University of Puerto Rico, PO Box 70377, San Juan, PR 00936-8377 (United States); Department of Chemistry, College of Natural Sciences, University of Puerto Rico, PO Box 70377, San Juan, PR 00936-8377 (United States); Rinaldi, Carlos, E-mail: carlos.rinaldi@bme.ufl.edu [J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, PO Box 116131, Gainesville, FL 32611-6131 (United States)

    2015-03-15

    Aggregation of magnetic nanoparticles in polymer melts was assessed using dynamic magnetic susceptibility measurements. Magnetic nanocomposites consisting of polybutadiene/CoFe{sub 2}O{sub 4} and polystyrene/CoFe{sub 2}O{sub 4} mixtures were prepared using different techniques and characterized using dynamic magnetic susceptibility measurements. The presence of nanoparticle aggregates determined using magnetic measurements was confirmed with transmission electron microscopy examinations. The results were in good agreement with predictions from the Flory–Huggins interaction parameters. - Highlights: • Oleic acid coated magnetic nanoparticles (MNPs) were dispersed in polymer melts. • MNPs dispersed well in polybutadiene but not in polystyrene. • Dynamic magnetic susceptibility (DMS) measurements assessed presence of aggregates. • DMS predictions were confirmed by transmission electron microscopy. • The Flory-Huggins interaction parameter correlated with MNP dispersion.

  12. Understanding the Magnetic Susceptibility Measurements by Using an Analytical Scale

    Science.gov (United States)

    Cano, M. E.; Cordova-Fraga, T.; Sosa, M.; Bernal-Alvarado, J.; Baffa, O.

    2008-01-01

    A description of the measurement procedure, related theory and experimental data analysis of the magnetic susceptibility of materials is given. A short review of previous papers in the line of this subject is presented. This work covers the whole experimental process, in detail, and presents a pragmatic approach for pedagogical sake. (Contains 2…

  13. Analysis of the susceptibility of condensed oxygen under high pressures and in strong magnetic fields

    Science.gov (United States)

    Kilit Doğan, E.; Yurtseven, H.

    2017-03-01

    The temperature dependence of the magnetic susceptibility is analyzed at some constant pressures by a power-law formula using the experimental data from the literature for the α - β and β - γ transitions in oxygen. A weak discontinuous (nearly continuous) transition occurring from the α to the β phase, becomes more discontinuous (weakly first order) for the β - γ transition as observed experimentally, which can be explained in terms of the critical exponents deduced from our analysis. The magnetic field dependence of the differential susceptibility is also analyzed in this study for the α -O2 at 4.2 K by a power-law formula using the experimental data. λ-type of observed behaviour of the differential susceptibility is discussed in terms of our analysis for the α -O2 .

  14. Dynamic magnetic hysteresis and nonlinear susceptibility of antiferromagnetic nanoparticles

    Science.gov (United States)

    Kalmykov, Yuri P.; Ouari, Bachir; Titov, Serguey V.

    2016-08-01

    The nonlinear ac stationary response of antiferromagnetic nanoparticles subjected to both external ac and dc fields of arbitrary strength and orientation is investigated using Brown's continuous diffusion model. The nonlinear complex susceptibility and dynamic magnetic hysteresis (DMH) loops of an individual antiferromagnetic nanoparticle are evaluated and compared with the linear regime for extensive ranges of the anisotropy, the ac and dc magnetic fields, damping, and the specific antiferromagnetic parameter. It is shown that the shape and area of the DMH loops of antiferromagnetic particles are substantially altered by applying a dc field that permits tuning of the specific magnetic power loss in the nanoparticles.

  15. Accuracy of MRI-based Magnetic Susceptibility Measurements

    Science.gov (United States)

    Russek, Stephen; Erdevig, Hannah; Keenan, Kathryn; Stupic, Karl

    Magnetic Resonance Imaging (MRI) is increasingly used to map tissue susceptibility to identify microbleeds associated with brain injury and pathologic iron deposits associated with neurologic diseases such as Parkinson's and Alzheimer's disease. Field distortions with a resolution of a few parts per billion can be measured using MRI phase maps. The field distortion map can be inverted to obtain a quantitative susceptibility map. To determine the accuracy of MRI-based susceptibility measurements, a set of phantoms with paramagnetic salts and nano-iron gels were fabricated. The shapes and orientations of features were varied. Measured susceptibility of 1.0 mM GdCl3 solution in water as a function of temperature agreed well with the theoretical predictions, assuming Gd+3 is spin 7/2. The MRI susceptibility measurements were compared with SQUID magnetometry. The paramagnetic susceptibility sits on top of the much larger diamagnetic susceptibility of water (-9.04 x 10-6), which leads to errors in the SQUID measurements. To extract out the paramagnetic contribution using standard magnetometry, measurements must be made down to low temperature (2K). MRI-based susceptometry is shown to be as or more accurate than standard magnetometry and susceptometry techniques.

  16. Magnetic Susceptibility of Molecular Carbon: Nanotubes and Fullerite

    Science.gov (United States)

    Ramirez, A. P.; Haddon, R. C.; Zhou, O.; Fleming, R. M.; Zhang, J.; McClure, S. M.; Smalley, R. E.

    1994-07-01

    Elemental carbon can be synthesized in a variety of geometrical forms, from three-dimensional extended structures (diamond) to finite molecules (C60 fullerite). Results are presented here on the magnetic susceptibility of the least well-understood members of this family, nanotubes and C60 fullerite. (i) Nanotubes represent the cylindrical form of carbon, intermediate between graphite and fullerite. They are found to have significantly larger orientation-averaged susceptibility, on a per carbon basis, than any other form of elemental carbon. This susceptibility implies an average band structure among nanotubes similar to that of graphite. (ii) High-resolution magnetic susceptibility data on C60 fullerite near the molecular orientational-ordering transition at 259 K show a sharp jump corresponding to 2.5 centimeter-gram-second parts per million per mole of C60. This jump directly demonstrates the effect of an intermolecular cooperative transition on an intramolecular electronic property, where the susceptibility jump may be ascribed to a change in the shape of the molecule due to lattice forces.

  17. Dynamic magnetic susceptibility of systems with long-range magnetic order

    Energy Technology Data Exchange (ETDEWEB)

    Vannette, Matthew Dano [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    The utility of the TDR as an instrument in the study of magnetically ordered materials has been expanded beyond the simple demonstration purposes. Results of static applied magnetic field dependent measurements of the dynamic magnetic susceptibility, χ, of various ferromagnetic (FM) and antiferromagnetic (AFM) materials showing a range of transition temperatures (1-800 K) are presented. Data was collected primarily with a tunnel diode resonator (TDR) at different radio-frequencies (~10-30 MHz). In the vicinity of TC local moment ferromagnets show a very sharp, narrow peak in χ which is suppressed in amplitude and shifted to higher temperatures as the static bias field is increased. Unexpectedly, critical scaling analysis fails for these data. It is seen that these data are frequency dependent, however there is no simple method whereby measurement frequency can be changed in a controllable fashion. In contrast, itinerant ferromagnets show a broad maximum in χ well below TC which is suppressed and shifts to lower temperatures as the dc bias field is increased. The data on itinerant ferromagnets is fitted to a semi-phenomenological model that suggests the sample response is dominated by the uncompensated minority spins in the conduction band. Concluding remarks suggest possible scenarios to achieve frequency resolved data using the TDR as well as other fields in which the apparatus may be exploited.

  18. Temperature dependence of magnetic moments of nanoparticles and their dipole interaction in magnetic fluids

    Energy Technology Data Exchange (ETDEWEB)

    Lebedev, A.V.

    2015-01-15

    Magnetic susceptibility measurements were carried out for magnetite-based fluids over a wide temperature range. The fluids were stabilized with commonly used surfactants (fatty acids) and new surfactants (polypropylene glycol and tallow acids). The coefficients of temperature dependence of the particle magnetic moments were determined by fitting of the measured and calculated values of magnetic susceptibility. The influence of the inter-particle dipole–dipole interaction on the susceptibility was taken into account in the framework of A.O. Ivanov's model. The corrections for thermal expansion were determined by density measurements of the carrier fluid. The obtained values of temperature coefficients correlate to the solidification temperature of the fluid samples. For fluids with a low solidification temperature the value of the temperature coefficient of particle magnetization coincides with its value for bulk magnetite. - Highlights: • Susceptibility measurements made for magnetic fluids over a wide temperature range. • Temperature coefficients of particle magnetization found from susceptibility data. • The value of coefficients correlates to the solidification temperature of the fluid. • For the lowest solidification temperature the coefficient corresponds to that of bulk magnetite.

  19. Eddy currents in the anisotropy of out-of-phase magnetic susceptibility measurement - A model study

    Science.gov (United States)

    Jezek, Josef; Hrouda, Frantisek

    2016-04-01

    Analytical solutions of Maxwell equations for eddy currents caused by AC field in a conductive sphere, known from 1950s, provide a general formula for magnetic susceptibility. It contains the parameters describing the sphere (its size, conductivity and permeability), surrounding medium (permeability) and the applied field (frequency). The formula is complex and without numerical evaluation it is difficult to distinguish the real (in-phase) and imaginary (out-of-phase) part of susceptibility. Representing all the parameters by only two, relative permeability (sphere vs. medium) and skin ratio (summarizing the effect of sphere size, conductivity and permeability, and frequency of the field), we derive approximate formulas for both phases and the phase angle. These are valid for a reasonable range of parameters (from rock magnetism point of view) and enable us to study their influence. The in-phase susceptibility depends very weakly on the fourth power of the skin ratio while the out-of-phase susceptibility depends more strongly on its second power. The coefficients of the dependence are expressed by means of relative permeability. The approximations of in-phase and out-of-phase susceptibilities provide a possibility to assess possible effects of eddy currents in rocks in case of low content of conductive minerals and solve problems of the type by which size one piece of a mineral in the measured sample can produce a phase shift that is observed by measurement. Examples of magnetite and pyrrhotite are given.

  20. Temperature dependence of topological susceptibility using gradient flow

    CERN Document Server

    Taniguchi, Yusuke; Kanaya, Kazuyuki; Kitazawa, Masakiyo; Suzuki, Hiroshi; Umeda, Takashi; Iwami, Ryo; Wakabayashi, Naoki

    2016-01-01

    We study temperature dependence of the topological susceptibility with the $N_{f}=2+1$ flavors Wilson fermion. We have two major interests in this paper. One is a comparison of gluonic and fermionic definitions of the topological susceptibility. Two definitions are related by the chiral Ward-Takahashi identity but their coincidence is highly non-trivial for the Wilson fermion. By applying the gradient flow both for the gauge and quark fields we find a good agreement of these two measurements. The other is a verification of a prediction of the dilute instanton gas approximation at low temperature region $T_{pc}< T<1.5T_{pc}$, for which we confirm the prediction that the topological susceptibility decays with power $\\chi_{t}\\propto(T/T_{pc})^{-8}$ for three flavors QCD.

  1. Characterization and quantification of path dependency in landslide susceptibility

    Science.gov (United States)

    Samia, Jalal; Temme, Arnaud; Bregt, Arnold; Wallinga, Jakob; Guzzetti, Fausto; Ardizzone, Francesca; Rossi, Mauro

    2017-09-01

    Landslides cause major environmental damage, economic losses and casualties. Although susceptibility to landsliding is usually considered an exclusively location-specific phenomenon, indications exist that landslide history co-determines susceptibility to future landslides. In this contribution, we quantified the role of landslide path dependency (the effect of landslides on landslides) using a multi-temporal landslide inventory from Italy. The fraction of landslides following earlier landslides in the same location exhibited an exponential decay, with susceptibility increasing 15-fold right after an initial landslide, and returning to pre-landslide values after about 25 years. We investigated the role of the geometry and location of a previous landslide for the occurrence of follow-up landslides. Larger landslides are more likely to cause follow-up landslides. Also landslide shape, topographic wetness index, the vertical distance to the nearest channel network, the absolute profile curvature and relative slope position of an earlier landslide, however, are important in predicting whether a follow-up landslide occurs. Combined in a binary logistic model, these attributes correctly predict 60% of times whether a landslide will be followed-up. These findings open the way for time-variant mapping of susceptibility to landslides, by including the effect of the spatio-temporal history of landsliding on susceptibility.

  2. Detecting compaction disequilibrium with anisotropy of magnetic susceptibility

    Science.gov (United States)

    Schwehr, Kurt; Tauxe, Lisa; Driscoll, Neal; Lee, Homa

    2006-11-01

    In clay-rich sediment, microstructures and macrostructures influence how sediments deform when under stress. When lithology is fairly constant, anisotropy of magnetic susceptibility (AMS) can be a simple technique for measuring the relative consolidation state of sediment, which reflects the sediment burial history. AMS can reveal areas of high water content and apparent overconsolidation associated with unconformities where sediment overburden has been removed. Many other methods for testing consolidation and water content are destructive and invasive, whereas AMS provides a nondestructive means to focus on areas for additional geotechnical study. In zones where the magnetic minerals are undergoing diagenesis, AMS should not be used for detecting compaction state. By utilizing AMS in the Santa Barbara Basin, we were able to identify one clear unconformity and eight zones of high water content in three cores. With the addition of susceptibility, anhysteretic remanent magnetization, and isothermal remanent magnetization rock magnetic techniques, we excluded 3 out of 11 zones from being compaction disequilibria. The AMS signals for these three zones are the result of diagenesis, coring deformation, and burrows. In addition, using AMS eigenvectors, we are able to accurately show the direction of maximum compression for the accumulation zone of the Gaviota Slide.

  3. Influence of Packing Size of Magnetic Filter on Efficiency of Catching Impurities with Different Dispersibility and Susceptibility

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The paper is devoted to investigation of influence of the size of a single filter packing on efficiency of catching impurities with various dispersity and magnetic susceptibility. It is revealed that the time of transferring of the process of cluster forming to stable state depends on packing size. The results can be used to make multilevel packings of magnetic filters.

  4. Magnetic resonance imaging susceptibility artifacts due to metallic foreign bodies.

    Science.gov (United States)

    Hecht, Silke; Adams, William H; Narak, Jill; Thomas, William B

    2011-01-01

    Susceptibility artifacts due to metallic foreign bodies may interfere with interpretation of magnetic resonance (MR) imaging studies. Additionally, migration of metallic objects may pose a risk to patients undergoing MR imaging. Our purpose was to investigate prevalence, underlying cause, and diagnostic implications of susceptibility artifacts in small animal MR imaging and report associated adverse effects. MR imaging studies performed in dogs and cats between April 2008 and March 2010 were evaluated retrospectively for the presence of susceptibility artifacts associated with metallic foreign bodies. Studies were performed using a 1.0 T scanner. Severity of artifacts was graded as 0 (no interference with area of interest), 1 (extension of artifact to area of interest without impairment of diagnostic quality), 2 (impairment of diagnostic quality but diagnosis still possible), or 3 (severe involvement of area of interest resulting in nondiagnostic study). Medical records were evaluated retrospectively to identify adverse effects. Susceptibility artifacts were present in 99/754 (13.1%) of MR imaging studies and were most common in examinations of the brachial plexus, thorax, and cervical spine. Artifacts were caused by identification microchips, ballistic fragments, skin staples/suture material, hemoclips, an ameroid constrictor, and surgical hardware. Three studies were nondiagnostic due to the susceptibility artifact. Adverse effects were not documented.

  5. Stress dependent vector magnetic properties in electrical steel

    Energy Technology Data Exchange (ETDEWEB)

    Ktena, Aphrodite, E-mail: aktena@teihal.gr [Department of Electrical Engineering, TEI of Chalkida, Psachna, Evia 34400 (Greece); Davino, Daniele; Visone, Ciro [Engineering Department, University of Sannio (Italy); Hristoforou, Evangelos [Laboratory of Metallurgy, National Technical University of Athens (Greece)

    2014-02-15

    The dependence of macroscopic magnetic properties on applied and residual stresses is promising for development of new magnetic non-destructive evaluation techniques in ferrous materials. The reliability of AC magnetometry, in determining the effect of strain on magnetic macroscopic parameters, is evaluated against scalar and vector Vibrating Sample Magnetometer measurements on strained electrical steel samples after unloading. Hysteresis loops have been measured at 0°, 30°, 45°, 60° and 90° to the direction of the applied stress. Vector magnetic properties reveal a stress-related anisotropy component, which increases with strain and deteriorates after fracture. The effect of residual stress on the saturation and remanent magnetization, as well as the differential susceptibility, is discussed with respect to data from AC magnetometry at 0.1 Hz. The results of the latter are representative of the magnetic configuration of the material under test and make it a promising candidate for NDE applications in steels.

  6. Spectroscopic AC susceptibility imaging (sASI) of magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ficko, Bradley W., E-mail: Bradley.W.Ficko@Dartmouth.edu; Nadar, Priyanka M.; Diamond, Solomon G.

    2015-02-01

    This study demonstrates a method for alternating current (AC) susceptibility imaging (ASI) of magnetic nanoparticles (mNPs) using low cost instrumentation. The ASI method uses AC magnetic susceptibility measurements to create tomographic images using an array of drive coils, compensation coils and fluxgate magnetometers. Using a spectroscopic approach in conjunction with ASI, a series of tomographic images can be created for each frequency measurement set and is termed sASI. The advantage of sASI is that mNPs can be simultaneously characterized and imaged in a biological medium. System calibration was performed by fitting the in-phase and out-of-phase susceptibility measurements of an mNP sample with a hydrodynamic diameter of 100 nm to a Brownian relaxation model (R{sup 2}=0.96). Samples of mNPs with core diameters of 10 and 40 nm and a sample of 100 nm hydrodynamic diameter were prepared in 0.5 ml tubes. Three mNP samples were arranged in a randomized array and then scanned using sASI with six frequencies between 425 and 925 Hz. The sASI scans showed the location and quantity of the mNP samples (R{sup 2}=0.97). Biological compatibility of the sASI method was demonstrated by scanning mNPs that were injected into a pork sausage. The mNP response in the biological medium was found to correlate with a calibration sample (R{sup 2}=0.97, p<0.001). These results demonstrate the concept of ASI and advantages of sASI. - Highlights: • Development of an AC susceptibility imaging model. • Comparison of AC susceptibility imaging (ASI) and susceptibility magnitude imaging (SMI). • Demonstration of ASI and spectroscopic ASI (sASI) using three different magnetic nanoparticle types. • SASI scan separation of three different magnetic nanoparticles samples using 5 spectroscopic frequencies. • Demonstration of biological feasibility of sASI.

  7. Cryogenic Magnetic Transition of D-and L-Alanine:Magnetic Field Dependence of Specific Heat and DC Magnetic Susceptibility%D-和L-丙氨酸的低温磁相变——磁场变化下的比热和直流磁化率

    Institute of Scientific and Technical Information of China (English)

    王文清; 沈新春; 龚

    2010-01-01

    To understand the intrinsic asymmetries of D-and L-alanine crystal lattices,the magnetic field dependence of zero-field and 1,3,and 5T on the heat capacity were measured from 2 to 20 K.The obtained heat capacity data shows linear behavior that follows:C(T)=aT3+b/T2.The first aT3 term is from the lattice phonon contribution with Cv=(12/5)π4R(T/⊙D)3 (⊙D is the Debye temperature).The second b/T2 term in the fitting formula is the magnetic contribution.In this experiment,the obtained Cp data for the D-and L-alanine single crystals show a Boson peak,which is seen as a maximum in the Cp/T3 versus Tplots in the low temperature region from 2-20 K at different fields.The four Cp/T3 versus T curves show a split between D-and L-alanine from 2-12 K and this is due to the magnetic contribution.This is absent between 12 and 20 K,which indicates the Schottky anomaly.The temperature of the Boson peak is 9.44 K for D-alanine and 10.86 K for L-alanine,and ⊙D is 151.5 and 152.7 K for D-alanine and L-alanine in zero-field,respectively.DC magnetic susceptibility data show the chiral behavior in nuclear spin-electron spin hyperfine interaction at very low temperature.%为了解D-和L-丙氨酸单晶品格在极低温下是否存在磁手性相变,在2-20 K下改变磁场强度(0,1,3,5T)测定其比热.实验结果表明比热和温度之间的函数关系很好地符合C(T)=aT3+b/T2方程,其中aT3项为晶格声子的贡献,可由公式Cv=(12/5)π4R(T/()D)3来描述(()D为德拜温度),b/T2项为磁场对比热的贡献.实验发现,在2-20 K范围内D-和L-丙氨酸单晶在不同磁场强度下均存在Boson峰(在Cp/T3-T曲线中表现为一个最大值).磁的贡献导致D-和L-丙氨酸单晶的四条Gp/T3-T曲线在2-12 K时不重合,且在12-20 K时消失,此即Schottky反常.零磁场下,D-和L-丙氨酸的Boson峰分别为9.44和10.86 K;德拜温度分别为151.5和152.7 K.结合磁场强度1 T下的直流磁化率测定,发现在温度低于5 K时,D-和L-丙氨酸单

  8. Temperature dependence of the AGOR magnetic field

    NARCIS (Netherlands)

    Roobol, LP; Brandenburg, S; Schreuder, HW; Baron, E; Lieuvin, M

    1999-01-01

    It has been found necessary to change the magnet currents gradually during long term operation of the AGOR cyclotron due to temperature changes in the iron, which are caused by the correction coils. These changes influence the magnetisation in various ways: through a change in susceptibility, satura

  9. Nonlinear dynamic susceptibilities of interacting and noninteracting magnetic nanoparticles

    CERN Document Server

    Joensson, P; García-Palacios, J L; Svedlindh, P

    2000-01-01

    The linear and cubic dynamic susceptibilities of solid dispersions of nanosized maghemite gamma-Fe sub 2 O sub 3 particles have been measured for three samples with a volume concentration of magnetic particles ranging from 0.3% to 17%, in order to study the effect of dipole-dipole interactions. Significant differences between the dynamic response of the samples are observed. While the linear and cubic dynamic susceptibilities of the most dilute sample compare reasonably well with the corresponding expressions proposed by Raikher and Stepanov for noninteracting particles, the nonlinear dynamic response of the most concentrated sample exhibits at low temperatures similar features as observed in a Ag(11 at% Mn) spin glass.

  10. PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) and EPI diffusion-weighted MR imaging at 3.0 T: pontine magnetic susceptibility artifacts depend on pneumatization of the sphenoid sinus

    Energy Technology Data Exchange (ETDEWEB)

    Sohn, Chul Ho; Kim, In Soo [College of Medicine, Keimyung University, Daegu (Korea, Republic of)

    2006-10-15

    In the case of well pneumatized sphenoid sinus, magnetic susceptibility artifact can be visualized at the brainstem and especially at the pons on echo-planar imaging (EPI) diffusion-weighted imaging. Fast spin-echo periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) is a novel imaging method that can reduce these artifacts. In 3.0 T MR, we first evaluate the degree of the relationship of pneumatization of the sphenoid sinus with the occurrence of magnetic susceptibility artifacts (MSA) on the echo planar imaging (EPI) diffusion-weighted imaging (DWI), and we evaluated using PROPELLER-DWI for cancellation of MSAs of the pons in the patients who had MSAs on the EPI-DWI. Sixty subjects (mean age: 58 years old and there were 30 men) who were classified according to the two types of sphenoid sinus underwent EPI-DWI. The two types of sphenoid sinus were classified by the degree of pneumatization on the sagittal T2-weighted image. The type-1 sphenoid sinus was 0% to less than 50% aeration of the bony sellar floor, and type-2 was 50% or more aeration of the boney sellar floor. Each of 10 subjects (n = 20/60, mean age: 53) of the two types had PROPELLER and EPI-DWI performed simultaneously. We first evaluated the absence or presence of MSAs at the pons in the two types, and we compared EPI and PROPELLER-DWI in the subjects who underwent the two MR sequences simultaneously. We used 3.0 T MR (Signa VHi, GE, MW, U.S.A.) with a standard head coil. All the MR images were interpreted by one neuroradiologiest. For the type-1, two (6.7%) cases had MSAs and 28 (93.7%) cases did not have MSAs on the EPI-DWI. For the type-2, twenty-seven (90%) cases had MSAs and 3 (10%) cases did not have MSAs on the EPI-DWI. The degree of pneumatization of the sphenoid sinus was related with the occurrence of MSAs of the pons, according to the chi-square test ({rho} = 0.000). All twenty cases who had PROPELLER-DWI performed had no MASs at the pons regardless of

  11. Magnetic susceptibility and relation to initial 87Sr/86Sr for granitoids of the central Sierra Nevada, California

    Science.gov (United States)

    Bateman, P.C.; Dodge, F.C.W.; Kistler, R.W.

    1991-01-01

    Measurement of the magnetic susceptibility of more than 6000 samples of granitic rock from the Mariposa 1?? by 2?? quadrangle, which crosses the central part of the Sierra Nevada batholith between 37?? and 38??N latitude, shows that magnetic susceptibility values are above 10-2 SI units in the east and central parts of the batholith and drop abruptly to less than 10-3 SI units in the western foothills. In a narrow transitional zone, intermediate values (10-3 to 10-2) prevail. Magnetic susceptibility appears to decrease slightly westward within the zones of both high and low values. Magnetic susceptibility in plutonic rocks is chiefly a function of the abundance of magnetite, which depends, in turn, on the total iron content of the rocks and their oxidation ratio. Correlations of magnetic susceptibility with initial 87Sr/86Sr suggest that oxidation ratios have been inherited from the source regions for the magmas from which the rocks crystallized. Reduction of Fe3+ to Fe2+ by organic carbon or other reducing substances may also have affected magnetic susceptibility. -from Authors

  12. The AC magnetic susceptibility of high temperature superconductors

    CERN Document Server

    Salim, M

    2001-01-01

    This research concerns the development of AC magnetic susceptometers and use of susceptometers in analysing high temperature superconductors. Two of the designs were a differential magnetic susceptometer (DMS) and a double coil screening susceptometer (DCSS) whose descriptions are given in detail including coil design, field measurements, susceptometer operation, experimental instrumentation, phase adjustment, susceptometer calibration and sensitivity for each design. Theoretical details are given regarding each design in order to calculate the complex external and internal susceptibility. Investigation concerning the demagnetisation factor of different geometries, and the significant features and limitation for each design are also provided. The susceptometers were applied to a wide range of YBCO samples, which includes bulk samples with different geometry (i.e. Slabs, disk, powder and thick film) and thin films with different oxygen contents. Several silver sheathed Bi-2223 tapes were also involved. This al...

  13. Mapping soil magnetic susceptibility and mineralogy in Ukraine

    Science.gov (United States)

    Menshov, Oleksandr; Pereira, Paulo; Kruglov, Oleksandr; Sukhorada, Anatoliy

    2017-04-01

    Soil suatainable planning is fundamental for agricultural areas. Soil mapping and modeling are increasingly used in agricultural areas in the entire world (Brevik et al., 2016). They are beneficial to land managers, to reduce soil degradation, increase soil productivity and their restoration. Magnetic susceptibility (MS) methods are low cost and accurate for the developing maps of agricultural areas.. The objective of this work is to identify the minerals responsible for MS increase in soils from the two study areas in Poltava and Kharkiv region. The thermomagnetic analyses were conducted using the KLY-4 with an oven apparatus. The hysteresis parameters were measured with the Rotating Magnetometer at the Geophysical Centre Dourbes, Belgium. The results showed that all of samples from Kharkiv area and the majortity of the samples collected in Poltava area represent the pseudo single domain (PSD) zone particles in Day plot. According to Hanesch et al. (2006), the transformation of goethite, ferrihydrite or hematite to a stronger ferrimagnetic phase like magnetite or maghemite is common in strongly magnetic soils with high values of organic carbon content. In our case of thermomagnetic study, the first peak on the heating curve near 260 ˚C indicates the presence of ferrihydrite which gradually transforms into maghemite (Jordanova et al., 2013). A further decrease in the MS identified on the heating curve may be related to the transformation of the maghemite to hematite. A second MS peak on the heating curve near 530 ˚C and the ultimate loss of magnetic susceptibility near 580 ˚C were caused by the reduction of hematite to magnetite. The shape of the thermomagnetic curves suggests the presence of single domain (SD) particles at room temperature and their transformation to a superparamagnetic (SP) state under heating. Magnetic mineralogical analyses suggest the presence of highly magnetic minerals like magnetite and maghemite as well as slightly magnetic goethite

  14. Zero-field-cooled and field-cooled magnetizations and magnetic susceptibility of itinerant ferromagnet SrRuO3

    Institute of Scientific and Technical Information of China (English)

    侯登录; 姜恩永; 白海力

    2002-01-01

    Zero-field-cooled (ZFC) magnetization, field-cooled (FC) magnetization, ac magnetic susceptibility and majorhysteresis loops of itinerant ferromagnet SrRuO3 have been measured at magnetic ordering temperatures ranging from5 to 160 K. An empirical model is proposed to calculate the measured ZFC magnetization. The result indicates that thecalculated ZFC magnetization compares well with the measured one. Based on the generalized Preisach model, boththe ZFC and FC curves are reproduced by numerical simulations. The critical temperature and critical exponents aredetermined by measuring the ac magnetic susceptibility in different bias magnetic fields at temperatures in the vicinityof the point of phase transition.

  15. Effect of Anti-dots on the Magnetic Susceptibility in a Superconducting Long Prism

    Science.gov (United States)

    Aguirre, C. A.; Joya, Miryam R.; Barba-Ortega, J.

    2017-02-01

    The magnetic susceptibility of a long mesoscopic superconducting square prism containing one/two (dot) anti-dots is calculated in the framework of the Ginzburg-Landau theoretical model. This magnetic susceptibility shows jumps at each of the vortex transition fields. We studied the influence of the number, size and geometry of the anti-dots on the magnetic susceptibility in a superconducting sample. We found interesting physical behavior when several kinds of materials filled into the anti-dot are considered.

  16. Magnetic susceptibility and magnetic resonance measurements of the moisture content and hydration condition of a magnetic mixture material

    Science.gov (United States)

    Tsukada, K.; Kusaka, T.; Saari, M. M.; Takagi, R.; Sakai, K.; Kiwa, T.; Bito, Y.

    2014-05-01

    We developed a magnetic measurement method to measure the moisture content and hydration condition of mortar as a magnetic mixture material. Mortar is a mixture of Portland cement, sand, and water, and these materials exhibit different magnetic properties. The magnetization-magnetic field curves of these components and of mortars with different moisture contents were measured, using a specially developed high-temperature-superconductor superconducting quantum interference device. Using the differences in magnetic characteristics, the moisture content of mortar was measured at the ferromagnetic saturation region over 250 mT. A correlation between magnetic susceptibility and moisture content was successfully established. After Portland cement and water are mixed, hydration begins. At the early stage of the hydration/gel, magnetization strength increased over time. To investigate the magnetization change, we measured the distribution between bound and free water in the mortar in the early stage by magnetic resonance imaging (MRI). The MRI results suggest that the amount of free water in mortar correlates with the change in magnetic susceptibility.

  17. Magnetic susceptibility and magnetic resonance measurements of the moisture content and hydration condition of a magnetic mixture material

    Energy Technology Data Exchange (ETDEWEB)

    Tsukada, K., E-mail: tsukada@cc.okayama-u.ac.jp; Kusaka, T.; Saari, M. M.; Takagi, R.; Sakai, K.; Kiwa, T. [The Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-Naka, Okayama 700-8530 (Japan); Bito, Y. [Central Research Lab., Hitachi. Ltd., 1-280 Higashi-Koigakubo, Kokubunji, Tokyo 185-8601 (Japan)

    2014-05-07

    We developed a magnetic measurement method to measure the moisture content and hydration condition of mortar as a magnetic mixture material. Mortar is a mixture of Portland cement, sand, and water, and these materials exhibit different magnetic properties. The magnetization–magnetic field curves of these components and of mortars with different moisture contents were measured, using a specially developed high-temperature-superconductor superconducting quantum interference device. Using the differences in magnetic characteristics, the moisture content of mortar was measured at the ferromagnetic saturation region over 250 mT. A correlation between magnetic susceptibility and moisture content was successfully established. After Portland cement and water are mixed, hydration begins. At the early stage of the hydration/gel, magnetization strength increased over time. To investigate the magnetization change, we measured the distribution between bound and free water in the mortar in the early stage by magnetic resonance imaging (MRI). The MRI results suggest that the amount of free water in mortar correlates with the change in magnetic susceptibility.

  18. Characterization and quantification of path dependency in landslide susceptibility

    NARCIS (Netherlands)

    Samia, Jalal; Temme, Arnaud; Bregt, Arnold; Wallinga, Jakob; Guzzetti, Fausto; Ardizzone, Francesca; Rossi, Mauro

    2017-01-01

    Landslides cause major environmental damage, economic losses and casualties. Although susceptibility to landsliding is usually considered an exclusively location-specific phenomenon, indications exist that landslide history co-determines susceptibility to future landslides. In this contribution,

  19. Magnetic Susceptibility of liquid Gd-NM (NM = Cu, Ga, Ge) alloys

    Science.gov (United States)

    Shimakura, Hironori; Tahara, Shuta; Okada, Tatsuya; Ohno, Satoru

    2017-08-01

    For rare earth alloys, the indirect interaction of RKKY is at work between rare-earth atoms. Therefore, the magnetism of them depends on the number of conduction electrons and the distance between rare-earth metals. In this work, to reveal the relationship between the number of conduction electrons and magnetic property of rare earth metal alloys, magnetic susceptibility measurements for liquid Gd-NM (NM = Cu, Ga, Ge) was performed by Faraday method. As the results, it was observed that the sign of paramagnetic Curie temperature of Cu-Gd alloys are positive at all composition, while Ga-Gd and Ge-Gd alloys show negative paramagnetic Curie temperature at certain composition. Moreover, it was indicated when the alloy at certain composition shows highest melting temperature, it has the lowest paramagnetic Curie temperature.

  20. Magnetic Susceptibility Measurements as a Proxy for Hydrocarbon Biodegradation

    Science.gov (United States)

    Mewafy, F.; Atekwana, E. A.; Slater, L. D.; Werkema, D.; Revil, A.; Ntarlagiannis, D.; Skold, M.

    2011-12-01

    Magnetic susceptibility (MS) measurements have been commonly used in paleoclimate studies, as a proxy for environmental pollution such as heavy metal contamination, and for delineating zones of oil seeps related to hydrocarbon exploration. Few studies have assessed the use of MS measurements for mapping zones of oil pollution. In this study, we investigated the variation in magnetic susceptibility across a hydrocarbon contaminated site undergoing biodegradation. Our objective was to investigate if MS measurements could be used as a proxy indicator of intrinsic bioremediation linked to the activity of iron reducing bacteria. An improved understanding of the mechanisms generating geophysical signatures associated with microbial enzymatic activity could permit the development of geophysical imaging technologies for long-term, minimally invasive and sustainable monitoring of natural biodegradation at oil spill sites. We used a Bartington MS probe to measure MS data along fifteen boreholes within contaminated (both free phase and dissolved phase hydrocarbon plumes) and clean areas. Our results show the following: (1) an enhanced zone of MS straddling the water table at the contaminated locations, not observed at the clean locations; (2) MS values within the free product plume are higher compared to values within the dissolved product plume; (3) the MS values within the vadoze zone above the free product plume are higher compared to values within the dissolved product plume; 4) the zone of high MS is thicker within the free product plume compared to the dissolved product plume. We suggest that the zone of enhanced MS results from the precipitation of magnetite related to the oxidation of the hydrocarbons coupled to iron reduction. Our data documents a strong correlation between MS and hydrocarbon concentration. We conclude that recognition of these zones of enhanced magnetite formation allows for the application of MS measurements as a: (1) low cost, rapid monitoring

  1. Effect of electron-electron interaction on the magnetic moment and susceptibility of a parabolic GaAs quantum dot

    Science.gov (United States)

    Boda, Aalu; Kumar, D. Sanjeev; Sankar, I. V.; Chatterjee, Ashok

    2016-11-01

    The problem of a parabolically confined two-dimensional semiconductor GaAs quantum dot with two interacting electrons in the presence of an external magnetic field and the spin-Zeeman interaction is studied using a method of numerical diagonalization. The energy spectrum is calculated as a function of the magnetic field. The magnetic moment (M) and the magnetic susceptibility (χ) show zero temperature diamagnetic peaks due to the exchange induced singlet-triplet transitions. The position and the number of these peaks depend both on the confinement strength of the quantum dot and the strength of the electron-electron interaction (β) .

  2. Critical behaviour of the local magnetic susceptibility in a ferromagnetic film

    Science.gov (United States)

    Korneta, W.; Pytel, Z.

    1985-07-01

    The nearest-neighbour Ising model of a ferromagnetic film in which couplings between surface spins may differ from couplings between remaining spins is considered. Using the mean-field approximation, the local magnetic susceptibility defined as the derivative of the local magnetization with respect to the external uniform magnetic field is obtained. The behaviour of the local magnetic susceptibility near the ordinary, surface-bulk and surface phase transitions and in a range of temperatures where physical quantities have pseudocritical behaviour is discussed. The critical behaviour of the local magnetic susceptibility in a three-dimensional semi-infinite model is also given for comparison.

  3. Models for the magnetic ac susceptibility of granular superferromagnetic CoFe/Al$_2$O$_3$

    OpenAIRE

    Petracic, O.; Glatz, A.; Kleemann, W.

    2004-01-01

    The magnetization and magnetic ac susceptibility, $\\chi = \\chi' - i \\chi''$, of superferromagnetic systems are studied by numerical simulations. The Cole-Cole plot, $\\chi''$ vs. $\\chi'$, is used as a tool for classifying magnetic systems by their dynamical behavior. The simulations of the magnetization hysteresis and the ac susceptibility are performed with two approaches for a driven domain wall in random media. The studies are motivated by recent experimental results on the interacting nano...

  4. Magnetic susceptibility induced white matter MR signal frequency shifts--experimental comparison between Lorentzian sphere and generalized Lorentzian approaches.

    Science.gov (United States)

    Luo, J; He, X; Yablonskiy, D A

    2014-03-01

    The nature of the remarkable phase contrast in high-field gradient echo MRI studies of human brain is a subject of intense debates. The generalized Lorentzian approach (He and Yablonskiy, Proc Natl Acad Sci USA 2009;106:13558-13563) provides an explanation for the anisotropy of phase contrast, the near absence of phase contrast between white matter and cerebrospinal fluid, and changes of phase contrast in multiple sclerosis. In this study, we experimentally validate the generalized Lorentzian approach. The Generalized Lorentzian Approach suggests that the local contribution to frequency shifts in white matter does not depend on the average tissue magnetic susceptibility (as suggested by Lorentzian sphere approximation), but on the distribution and symmetry of magnetic susceptibility inclusions at the cellular level. We use ex vivo rat optic nerve as a model system of highly organized cellular structure containing longitudinally arranged myelin and neurofilaments. The nerve's cylindrical shape allowed accurate measurement of its magnetic susceptibility and local frequency shifts. We found that the volume magnetic susceptibility difference between nerve and water is -0.116 ppm, and the magnetic susceptibilities of longitudinal components are -0.043 ppm in fresh nerve, and -0.020 ppm in fixed nerve. The frequency shift observed in the optic nerve as a representative of white matter is consistent with generalized Lorentzian approach but inconsistent with Lorentzian sphere approximation. Copyright © 2013 Wiley Periodicals, Inc.

  5. Magnetic susceptibilities of liquid Cr-Au, Mn-Au and Fe-Au alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ohno, S.; Shimakura, H. [Niigata University of Pharmacy and Applied Life Sciences, Higashijima, Akiha-ku, Niigata 956-8603 (Japan); Tahara, S. [Faculty of Science, University of the Ryukyus, Nishihara-cho, Okinawa 903-0213 (Japan); Okada, T. [Niigata College of Technology, Kamishin’eicho, Nishi-ku, Niigata 950-2076 (Japan)

    2015-08-17

    The magnetic susceptibility of liquid Cr-Au, Mn-Au, Fe-Au and Cu-Au alloys was investigated as a function of temperature and composition. Liquid Cr{sub 1-c}Au{sub c} with 0.5 ≤ c and Mn{sub 1-c}Au{sub c} with 0.3≤c obeyed the Curie-Weiss law with regard to their dependence of χ on temperature. The magnetic susceptibilities of liquid Fe-Au alloys also exhibited Curie-Weiss behavior with a reasonable value for the effective number of Bohr magneton. On the Au-rich side, the composition dependence of χ for liquid TM-Au (TM=Cr, Mn, Fe) alloys increased rapidly with increasing TM content, respectively. Additionally, the composition dependences of χ for liquid Cr-Au, Mn-Au, and Fe-Au alloys had maxima at compositions of 50 at% Cr, 70 at% Mn, and 85 at% Fe, respectively. We compared the composition dependences of χ{sub 3d} due to 3d electrons for liquid binary TM-M (M=Au, Al, Si, Sb), and investigated the relationship between χ{sub 3d} and E{sub F} in liquid binary TM-M alloys at a composition of 50 at% TM.

  6. The initial magnetic susceptibility of polydisperse ferrofluids: A comparison between experiment and theory over a wide range of concentration

    Science.gov (United States)

    Solovyova, Anna Y.; Goldina, Olga A.; Ivanov, Alexey O.; Lebedev, Aleksandr V.; Elfimova, Ekaterina A.

    2016-08-01

    Temperature dependencies of the static initial magnetic susceptibility for ferrofluids at various concentrations are studied using experiment and statistical-mechanical theories. Magnetic susceptibility measurements are carried out for twelve samples of magnetite-based fluids stabilized with oleic acid over a wide range of temperatures (210 K ≲T ≲ 390 K); all samples have the same granulometric composition but different volume ferroparticle concentrations (0.2 ≲ φ ≲ 0.5). Experimental results are analyzed using three theories: the second-order modified mean-field theory (MMF2) [A. O. Ivanov and O. B. Kuznetsova, Phys. Rev. E 64, 41405 (2001)]; its correction for polydisperse ferrofluids arising from Mayer-type cluster expansion and taking into account the first terms of the polydisperse second virial coefficient [A. O. Ivanov and E. A. Elfimova, J. Magn. Magn. Mater 374, 327 (2015)]; and a new theory based on MMF2 combined with the first terms of the polydisperse second and third virial contributions to susceptibility. It turns out that the applicability of each theory depends on the experimental sample density. If twelve ferrofluid samples are split into three groups of strong, moderate, and low concentrated fluids, the temperature dependences of the initial magnetic susceptibility in each group are very precisely described by one of the three theories mentioned above. The determination of a universal formula predicting a ferrofluid susceptibility over a broad range of concentrations and temperatures remains as a challenge.

  7. Approximate relationship of coal bed methane and magnetic characteristics of rock via magnetic susceptibility logging

    Science.gov (United States)

    Zhao, Yonghui; Wu, Jiansheng; Zhang, Pingsong; Xiao, Pengfei

    2012-02-01

    In coal bed methane (CBM) exploration, how to improve the accuracy for locating and evaluating the CBM deposits is still a problem due to the rarity of occurrence of CBM. Combined with the distribution of the CBM content in the Huainan coalfield, the approximate relationship between the occurrence of CBM and the magnetic properties of the coal bed and adjacent mudstone have been widely discussed by magnetic logging. Experimental results show that magnetic susceptibility of the coal bed and adjacent mudstone would clearly increase with the CBM content in a coal bed. According to the results of the experiment, the prediction of the CBM content has been accomplished for different coal beds, and the results are consistent with the distribution of the CBM content throughout the whole coalfield. Preliminary data analysis reveals that there is indeed a correlation between the changes of magnetic rock characteristics and the occurrence of the CBM, and this finding may shed some light on the evaluation of CBM.

  8. Second-order-like cluster-monomer transition within magnetic fluids and its impact upon the magnetic susceptibility.

    Science.gov (United States)

    Zhong, Jing; Xiang, Qing; Massa, Letícia O; Qu, Fanyao; Morais, Paulo C; Liu, Wenzhong

    2012-03-05

    The low-field (below 5 Oe) ac and dc magnetic response of a magnetic fluid [MF] sample in the range of 305 to 360 K and 410 to 455 K was experimentally and theoretically investigated. We found a systematic deviation of Curie's law, which predicts a linear temperature dependence of inverse initial susceptibility in the range of our investigation. This finding, as we hypothesized, is due to the onset of a second-order-like cluster-to-monomer transition with a critical exponent which is equal to 0.50. The susceptibility data were well fitted by a modified Langevin function, in which cluster dissociation into monomers, at the critical temperature [T*], was included. In the ac experiments, we found that T* was reducing from 381.8 to 380.4 K as the frequency of the applied field increases from 123 to 173 Hz. In addition, our ac experiments confirm that only monomers respond for the magnetic behavior of the MF sample above T*. Furthermore, our Monte Carlo simulation and analytical results support the hypothesis of a thermal-assisted dissociation of chain-like structures.PACS: 75.75.-C; 75.30.Kz; 75.30.Cr.

  9. 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.

  10. Frequency dependent magnetization of superconductor strip

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Kailash Prasad [Landcare Research, Palmerston North (New Zealand); Raj, Ashish [Computer Science in Radiology, Weill Medical College, Cornell University, NY (United States); Brandt, Ernst Helmut [Max-Planck-Institut fuer Metallforschung, POB 800665, D-70506 Stuttgart (Germany); Sastry, Pamidi V P S S, E-mail: thakurk@landcareresearch.co.nz, E-mail: asr2004@med.cornell.edu, E-mail: ehb@mf.mpg.de, E-mail: pamidi@caps.fsu.edu [Center for Advanced Power Systems, Florida State University, Tallahassee, FL 32310 (United States)

    2011-04-15

    The frequency dependence of magnetic ac loss of thin superconductor strip subjected to an ac magnetic field perpendicular to the surface of the strip is investigated by incorporating a flux creep model into the critical state model of Brandt and Indenbom. It is found that the reduced ac loss exhibits a maximum value at a frequency f{sub m}, which is a rapidly varying function of the applied ac magnetic field. At low magnetic field, f{sub m} becomes zero, and ac loss decreases with frequency as a power law ({approx}f{sup -2/n}). Whereas at high magnetic field f{sub m} becomes infinite and ac loss increases with frequency, still following the power law ({approx}f{sup 1/n}). The analytical results are substantiated with experimental data and the results of a 2D finite element simulation.

  11. Impacts of geology and land use on magnetic susceptibility and selected heavy metals in surface soils of Mashhad plain, northeastern Iran

    Science.gov (United States)

    Karimi, Alireza; Haghnia, Gholam Hosain; Ayoubi, Shamsollah; Safari, Tayebeh

    2017-03-01

    Magnetic susceptibility is a fast, inexpensive and reliable technique for estimating and monitoring the anthropogenic contamination of soil with heavy metals. However, it is essential to determine the factors affecting magnetic susceptibility before applying this technique to environmental studies. The objectives of this study were to investigate i) the effect of parent materials and land use on the magnetic susceptibility and concentrations of Fe, Ni, Pb and Zn, and ii) capability of magnetic susceptibility as an indicator of anthropogenic heavy metals contamination of soil in Mashhad plain, northeastern Iran. One hundred seventy-eight composite surface soil samples (0-10 cm) were taken. The aqua-regia extractable concentrations of Fe, Ni, Zn and Pb were determined by atomic absorption spectroscopy. Magnetic susceptibility at low and high frequency (χlf and χhf) were measured and frequency dependent susceptibility (χfd) was calculated. The average concentrations of Fe, Ni, Pb and Zn were 22,812, 61.4, 74.1 and 31.6 mg kg- 1, respectively. The highest contents of Pb (69.1 mg kg- 1) and Zn (149 mg kg- 1) were observed in urban area. The highest concentration of Ni was 41,538 mg kg- 1 observed in the soils developed from ultramafic rocks. Magnetic susceptibility varied from 20.3 on marly sediments to 311.8 × 10- 8 m3 kg- 1 on ultramafic rocks. A positive strong correlation (Pvalue < 0.01, r = 0.88) was obtained between Ni and χlf. There were no significant relationships between Zn and Pb with χlf, therefore it seems that magnetic susceptibility has not been affected significantly by anthropogenic activities which enhanced Pb and Zn concentrations in urban soils. The results indicated that magnetic susceptibility was mainly controlled by Ni containing minerals with lithogenic origin. Therefore, in the soils studied, magnetic susceptibility could not be employed as indicator of anthropogenic contamination of soil with heavy metals.

  12. Comparison of optomagnetic and AC susceptibility readouts in a magnetic nanoparticle agglutination assay for detection of C-reactive protein

    DEFF Research Database (Denmark)

    Fock, Jeppe; Parmvi, Mattias; Strömberg, Mattias

    2017-01-01

    conjugated with CRP antibodies. Both methods detect agglutination as a shift to lower frequencies in measurements of the dynamics in response to an applied oscillating magnetic field. The magnetic susceptibility method probes the magnetic response whereas the optomagnetic technique probes the modulation...... of laser light transmitted through the sample. The two techniques provided highly correlated results upon agglutination when they measure the decrease of the signal from the individual MNPs (turn-off detection strategy), whereas the techniques provided different results, strongly depending on the read...

  13. Magnetic susceptibility, chemical element content and morphology of magnetic mineral in surface sediment of Kamp Walker and Hubay rivers as an inlet of Sentani lake, Papua-Indonesia

    Science.gov (United States)

    Zulaikah, Siti; Sisinggih, Dian; Bungkang, Yusuf; Dani, Zem; Ong, Mahfud David

    2017-07-01

    As an inlet of Sentani lake, Kamp Walker and Hubay rivers have a different environment characteristic, i.e. Kamp Walker has a proximate inhabitant, while Hubay has a relatively more natural environment. In this study, we conduct measurement of magnetic susceptibility, Fe content and morphology of magnetic mineral extracted from the two rivers surface sediment. The magnetic susceptibility of low frequency (χlf) of sediment samples from the two rivers are varies from 11.11 × 10-6 kg/m3 to 24.96 10-6 kg/m3 for Kamp Walker with dependence frequency susceptibility (χfd) from 0.031% to 0.367%. Meanwhile, for HubayRivers we find the χlf varies from 4.56 × 10-6 kg/m3 to 16.93 × 10-6 kg/m3 and χfd from 0.104% to 1.033%. Fe content of the sample from the two river are also has a different average i.e around 60% for Hubay and 50% for Kamp Walker, that may because of the source of magnetic minerals on sediment are mainly a lithogenic magnetic mineral in Hubay, and anthropogenic magnetic mineral in Kamp Walker. The morphology of magnetic mineral, based on the SEM image shows a rounded and crystalline shape.

  14. Basaltic lava characterization using magnetic susceptibility identification and presence of opaque minerals in Ijen volcanic complex, Banyuwangi, East Java

    Science.gov (United States)

    Pratama, Aditya; Hafidz, Abd.; Bijaksana, Satria; Abdurrachman, Mirzam

    2017-07-01

    Reliable volcanic map and deep understanding of magmatic processes are very important in exploration of natural resources and mitigation of volcanic hazards. The conservative method in volcanic mapping still depends on qualitative approach thus it often failed to characterize volcanic products properly. Rock magnetic methods are quantitative approaches that classify rocks based on their magnetic properties. In this study, magmatic processes in basaltic lavas from Ijen volcanic complex in Banyuwangi, East Java were studied using combined rock magnetic and petrogenesis approaches. Samples of basaltic lavas from 13 localities, taken from three eruption sources were measuredfor their mass-specific magnetic susceptibility. The samples were then also subjected to petrographic and X-ray Fluorescence Spectrometry (XRF) analyses for their minerals composition and petrogenesis. Preliminary results show that the distinction in magnetic characters might be due to the quantity of magnetic minerals contained in rocks.

  15. Complex magnetic susceptibility setup for spectroscopy in the extremely low-frequency range

    NARCIS (Netherlands)

    Kuipers, B.W.M.; Bakelaar, I.A.; Klokkenburg, M.; Erne, B.H.

    2008-01-01

    A sensitive balanced differential transformer was built to measure complex initial parallel magnetic susceptibility spectra in the 0.01–1000 Hz range. The alternating magnetic field can be chosen sufficiently weak that the magnetic structure of the samples is only slightly perturbed and the low freq

  16. Determination of Magnetic Parameters of Maghemite (γ-Fe2O3) Core-Shell Nanoparticles from Nonlinear Magnetic Susceptibility Measurements

    Science.gov (United States)

    Syvorotka, Ihor I.; Pavlyk, Lyubomyr P.; Ubizskii, Sergii B.; Buryy, Oleg A.; Savytskyy, Hrygoriy V.; Mitina, Nataliya Y.; Zaichenko, Oleksandr S.

    2017-04-01

    Method of determining of magnetic moment and size from measurements of dependence of the nonlinear magnetic susceptibility upon magnetic field is proposed, substantiated and tested for superparamagnetic nanoparticles (SPNP) of the "magnetic core-polymer shell" type which are widely used in biomedical technologies. The model of the induction response of the SPNP ensemble on the combined action of the magnetic harmonic excitation field and permanent bias field is built, and the analysis of possible ways to determine the magnetic moment and size of the nanoparticles as well as the parameters of the distribution of these variables is performed. Experimental verification of the proposed method was implemented on samples of SPNP with maghemite core in dry form as well as in colloidal systems. The results have been compared with the data obtained by other methods. Advantages of the proposed method are analyzed and discussed, particularly in terms of its suitability for routine express testing of SPNP for biomedical technology.

  17. Zero—field—cooled and field—cooled magnetizations and magnetic susceptibility of itinerant ferromagnet SrRuO3

    Institute of Scientific and Technical Information of China (English)

    侯登录; 姜恩永; 等

    2002-01-01

    Zero-field-cooled(ZFC) magnetization,field-cooled(FC) magnetization,ac magnetic susceptibility and major hysteresis loops of itinerant ferromagnet SrRuO3 have been measured at magnetic ordering temperatures ranging from 5 to 160K.An empirical model is proposed to calculate the measured ZFC magnetization.The result indicates that the calculated ZFC magnetization compares well with the measured one.Based on the generalized Preisach model.both the ZFC and FC curves are reproduced by numerical simulations.The critical temperature and critical exponents are determined by measuring the ac magnetic susceptibility in different bias magnetic fields at temperatures in the vicinity of the point of phase transition.

  18. Anisotropy of out-of-phase magnetic susceptibility of rocks as a tool for direct determination of magnetic subfabrics of some minerals: an introductory study

    Science.gov (United States)

    Hrouda, František; Chadima, Martin; Ježek, Josef; Pokorný, Jiří

    2017-01-01

    The magnetic susceptibility measured in alternating field can in general be resolved into a component that is in-phase with the applied field and a component that is out-of-phase. While in non-conductive diamagnetic, paramagnetic and many ferromagnetic materials the phase is effectively zero, in some ferromagnetic minerals, such as pyrrhotite, hematite, titanomagnetite or small magnetically viscous grains of magnetite, it is clearly non-zero. The anisotropy of out-of-phase susceptibility (opAMS) can then be used as a tool for the direct determination of the magnetic subfabrics of the minerals with non-zero phase. The error in determination of out-of-phase susceptibility non-linearly increases with decreasing phase angle. This may result in imprecise determination of the opAMS in specimens with very low phase angle. The degree of opAMS is higher than that of ipAMS, which may in contrast result in slightly increasing precision n the opAMS determination. It is highly recommended to inspect the results of the statistical tests of each specimen and to exclude the specimens whose opAMS is determined with insufficient precision from further processing. In rocks, whose magnetism is dominated by the mineral with non-zero out-of-phase susceptibility, the principal directions of the opAMS and ipAMS are virtually coaxial, while the degree of opAMS is higher than that of ipAMS. In some specific cases, the opAMS provides us with similar data to those provided by anisotropies of low-field dependent susceptibility and frequency-dependent susceptibility. The advantage of the opAMS compared to the other two anisotropies is its simultaneous measurement with the ipAMS during one measuring process, while the other two anisotropies require the AMS measurements in several fields or at least at two operating frequencies.

  19. Using magnetic susceptibility to discriminate between soil moisture regimes in selected loess and loess-like soils in northern Iran

    Science.gov (United States)

    Valaee, Morteza; Ayoubi, Shamsollah; Khormali, Farhad; Lu, Sheng Gao; Karimzadeh, Hamid Reza

    2016-04-01

    This study used discriminant analysis to determine the efficacy of magnetic measures for discriminating between four soil moisture regimes in northern Iran. The study area was located on loess deposits and loess-like soils containing similar parent material. Four soil moisture regimes including aridic, xeric, udic, and aquic were selected. A total of 25 soil profiles were drug from each regime and composite soil samples were collected within the moisture control section. A set of magnetic measures including magnetic susceptibility at low (χlf) and high (χhf) frequencies, frequency-dependent magnetic susceptibility (χfd), saturation isothermal remnant magnetization (SIRM), and isothermal remnant magnetization (IRM100 mT, IRM 20 mT) were measured in the laboratory. Dithionite citrate bicarbonate (Fed) and acid oxalate (Feo) contents of all soil samples were also determined. The lowest and highest χlf and χhf were observed in aquic and udic moisture regimes, respectively. A similar trend was obtained for Fed and Fed-Feo. The significant positive correlation between Fed and SIRM (r = 0.60; P < 0.01) suggested the formation of stable single domains (SSD) due to pedogenic processes. The results of discriminant analysis indicated that a combination of magnetic measures could successfully discriminate between the selected moisture regimes in the study area (average accuracy = 80%). It can thus be concluded that magnetic measures could be applied as a powerful indicator for differentiation of soil moisture regimes in the study area.

  20. Static dipole magnetic susceptibilities of relativistic hydrogenlike atoms: A semianalytical approach

    Science.gov (United States)

    Poszwa, A.; Rutkowski, A.

    2007-03-01

    The binding energies and magnetic susceptibilities for states evolving from 1s1/2 , 2s1/2 , 2p1/2 , 2p3/2 , 3s1/2 , 3d3/2 , and 3d5/2 are calculated using power-series solutions of the Dirac equation for hydrogenic atoms in static and uniform magnetic B . The accuracy of the binding energies for low and medium magnetic fields exceeds that of previous variational calculations. In the low-magnetic-field limit the highly accurate values of energies are used to determine the relativistic Paschen-Back effect and relativistic magnetic susceptibilities by expansion of the fully relativistic energy into power series of the parameter B/Z2 . The linear term of this series is related to the relativistic Paschen-Back effect and the square term is proportional to the relativistic dipole magnetic susceptibility of the atom.

  1. Chalcogen-height dependent magnetic interactions and magnetic order switching in FeSexTe1-x.

    Science.gov (United States)

    Moon, Chang-Youn; Choi, Hyoung Joon

    2010-02-05

    Magnetic properties of iron chalcogenide superconducting materials are investigated using density-functional calculations. We find that the stability of magnetic phases is very sensitive to the height of chalcogen species from the Fe plane: while FeTe with optimized Te height has the double-stripe (pi, 0) magnetic ordering, the single-stripe (pi, pi) ordering becomes the ground state when Te is lowered below a critical height by, e.g., Se doping. This behavior is understood by opposite Te-height dependences of the superexchange interaction and a longer range magnetic interaction mediated by itinerant electrons. We also demonstrate a linear temperature dependence of the macroscopic magnetic susceptibility in the single-stripe phase in contrast with the constant behavior in the double-stripe phase. Our findings provide a comprehensive and unified view on the magnetism in FeSexTe1-x and iron pnictide superconductors.

  2. Investigation of the complex susceptibility of magnetic beads containing maghemite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Fannin, P.C. [Department of Electronic and Electrical Engineering, Trinity College, Dublin 2 (Ireland)]. E-mail: pfannin@tcd.ie; Cohen-Tannoudji, L. [Laboratoire Colloides et Materiaux Divises, CNRS UMR7612, ESPCI, 10 Rue Vauquelin, F-75005, Paris (France); Bertrand, E. [Laboratoire Colloides et Materiaux Divises, CNRS UMR7612, ESPCI, 10 Rue Vauquelin, F-75005, Paris (France); Giannitsis, A.T. [Department of Electronic and Electrical Engineering, Trinity College, Dublin 2 (Ireland); Mac Oireachtaigh, C. [Department of Electronic and Electrical Engineering, Trinity College, Dublin 2 (Ireland); Bibette, J. [Laboratoire Colloides et Materiaux Divises, CNRS UMR7612, ESPCI, 10 Rue Vauquelin, F-75005, Paris (France)

    2006-08-15

    We report on frequency and field-dependent complex susceptibility, {chi}{sub s}({omega})={chi}{sub s}{sup '}({omega})-i{chi}{sub s}{sup '}'({omega}), measurements of a magnetic colloidal system consisting of 200nm spherical beads, containing maghemite ({gamma}Fe{sub 2}O{sub 3}) nanoparticles. The relaxation properties of both the magnetic colloid and a free suspension of the {gamma}Fe{sub 2}O{sub 3} particles, are investigated over the frequency range 200Hz-1MHz. Under a polarizing field H, an absorption peak is detected in the {chi}{sub s}{sup '}' component at frequencies f{sub max} between 1.1 and 1.7kHz. We show that this absorption peak can be attributed to the Neel relaxation of the inner maghemite nanoparticles. It is also shown that the general trend for the value of f{sub max} and the amplitude of both {chi}{sub s}{sup '} and {chi}{sub s}{sup '}' is to increase with increasing H. Furthermore, the relation between {chi}{sub s}{sup '}({omega}) and {chi}{sub s}{sup '}'({omega}) and their dependence on frequency, {omega}/2{pi}, is investigated by means of the magnetic analogue of the Cole-Cole plot and a measure of the Cole-Cole distribution parameter {alpha}{sub s} is determined.

  3. Classification of soil magnetic susceptibility and prediction of metal detector performance: case study of Angola

    Science.gov (United States)

    Preetz, Holger; Altfelder, Sven; Hennings, Volker; Igel, Jan

    2009-05-01

    Soil magnetic properties can seriously impede the performance of metal detectors used in landmine clearance operations. For a proper planning of clearance operations pre-existing information on soil magnetic susceptibility can be helpful. In this study we briefly introduce a classification system to assess soil magnetic susceptibilities from geoscientific maps. The classification system is based on susceptibility measurements conducted on archived lateritic soil samples from 15 tropical countries. The system is applied to a soil map of Angola, resulting in a map that depicts soil magnetic susceptibilities as a worst case scenario. An additional layer depicting the surveyed mine affected communities in Angola is added to the map, which demonstrates that a large number of those are located in areas where soil is expected to impede metal detector performance severely.

  4. Longitudinal Susceptibility of S = 1/2 Low-Dimensional Heisenberg Ferromagnet in a Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    CHEN Yuan; XIANG Ying; HU Ai-Yuan

    2008-01-01

    Longitudinal susceptibility of the spin-1/2 low-dimensional Heisenberg ferromagnet in a magnetic field, is studied by the Green's function method within the random phase approximation. The static and dynamic longitudinal susceptibilities are calculated in the low- and high-field regions. Power laws for the position and height of the static susceptibility maximum are shown not to support the predictions of Landau theory.

  5. Magnetic susceptibility of the QCD vacuum in a nonlocal SU(3) PNJL model

    CERN Document Server

    Pagura, V P; Noguera, S; Scoccola, N N

    2016-01-01

    The magnetic susceptibility of the QCD vacuum is analyzed in the framework of a nonlocal SU(3) Polyakov-Nambu-Jona-Lasinio model. Considering two different model parametrizations, we estimate the values of the $u$ and $s$-quark tensor coefficients and magnetic susceptibilities and then we extend the analysis to finite temperature systems. Our numerical results are compared to those obtained in other theoretical approaches and in lattice QCD calculations.

  6. Influence of dipolar interactions on the magnetic susceptibility spectra of ferrofluids

    Science.gov (United States)

    Sindt, Julien O.; Camp, Philip J.; Kantorovich, Sofia S.; Elfimova, Ekaterina A.; Ivanov, Alexey O.

    2016-06-01

    The frequency-dependent magnetic susceptibility of a ferrofluid is calculated under the assumption that the constituent particles undergo Brownian relaxation only. Brownian-dynamics simulations are carried out in order to test the predictions of a recent theory [A. O. Ivanov, V. S. Zverev, and S. S. Kantorovich, Soft Matter 12, 3507 (2016), 10.1039/C5SM02679B] that includes the effects of interparticle dipole-dipole interactions. The theory is based on the so-called modified mean-field approach and possesses the following important characteristics: in the low-concentration, noninteracting regime, it gives the correct single-particle Debye-theory results; it yields the exact leading-order results in the zero-frequency limit; it includes particle polydispersity correctly from the outset; and it is based on firm theoretical foundations allowing, in principle, systematic extensions to treat stronger interactions and/or higher concentrations. The theory and simulations are compared in the case of a model monodisperse ferrofluid, where the effects of interactions are predicted to be more pronounced than in a polydisperse ferrofluid. The susceptibility spectra are analyzed in detail in terms of the low-frequency behavior, the position of the peak in the imaginary (out-of-phase) part, and the characteristic decay time of the magnetization autocorrelation function. It is demonstrated that the theory correctly predicts the trends in all of these properties with increasing concentration and dipolar coupling constant, the product of which is proportional to the Langevin susceptibility χL. The theory is in quantitative agreement with the simulation results as long as χL≲1 .

  7. Rock magnetic and anisotropy of magnetic susceptibility(AMS) of earthquake affected soft sediments: Examples from Shillong and Latur (Deccan Trap), India.

    Science.gov (United States)

    Lakshmi, B. V., ,, Dr.; Gawali, Mr. Praveen B.; Deenadayalan, K., ,, Dr.; Ramesh, D. S., ,, Prof.

    2017-04-01

    Rock magnetic and anisotropy of magnetic susceptibility (AMS) of earthquake affected soft sediments: Examples from Shillong and Latur (Deccan Trap), India. B.V.Lakshmi, Praveen B.Gawali, K.Deenadayalan and D.S.Ramesh Indian Institute of Geomagnetism, plot 5, sector 18, Near Kalamboli Highway, New Panvel(W), Navi Mumbai 410218 Combined rock magnetism and anisotropy of magnetic susceptibility (AMS) studies on earthquake induced soft and non-soft sediments from Shillong and Latur, India have thrown up interesting results. The morphology of hysteresis loops, the pattern of isothermal remanent magnetization (IRM) acquisition, and temperature dependence of susceptibility indicate that titano-magnetite/magnetite is the main magnetic carrier in these sediments. We also analyzed the anisotropy of magnetic susceptibility (AMS) of liquefaction features within the seismically active Dauki fault, Shillong Plateau. We discovered that host sediments (non-liquefied), are characterized by an oblate AMS ellipsoid and liquefied sediment are characterized by a triaxial AMS ellipsoid, well grouped maximum susceptibility axis K1 (NNW-SSE trend). Field evidence and AMS analysis indicate that most of these features were emplaced by injection inferred to be due to seismically triggered fluidization. Anisotropy of magnetic susceptibility (AMS) of deformed and undeformed unconsolidated clay samples of Deccan Trap terrain from the 2000-year-old paleoearthquake site of Ther village, Maharashtra, India, was also studied. Such deposits are rare in the compact basaltic terrain because of which the results acquired are very important. The undeformed clay samples exhibit typical sedimentary fabric with an oblate AMS ellipsoid, whereas the deformed samples are tightly grouped in the inferred compression direction, probably effected by an earthquake, exhibiting prolate as well as oblate AMS ellipsoids. Rock magnetic and AMS methodology can help understand the behavior of different sediments to the

  8. Lengthscale dependence of dynamic four-point susceptibilities in glass formers

    OpenAIRE

    Chandler, David; Juan P Garrahan; Jack, Robert L.; Maibaum, Lutz; Pan, Albert C.

    2006-01-01

    Dynamical four-point susceptibilities measure the extent of spatial correlations in the dynamics of glass forming systems. We show how these susceptibilities depend on the length scales that necessarily form part of their definition. The behaviour of these susceptibilities is estimated by means of an analysis in terms of renewal processes within the context of dynamic facilitation. The analytic results are confirmed by numerical simulations of an atomistic model glass-former, and of two kinet...

  9. Static electric and magnetic multipole susceptibilities for Dirac one-electron atoms in the ground state

    Science.gov (United States)

    Szmytkowski, Radosław; Łukasik, Grzegorz

    2016-09-01

    We present tabulated data for several families of static electric and magnetic multipole susceptibilities for hydrogenic atoms with nuclear charge numbers from the range 1 ⩽ Z ⩽ 137. Atomic nuclei are assumed to be point-like and spinless. The susceptibilities considered include the multipole electric polarizabilities α E L → E L and magnetizabilities (magnetic susceptibilities) χ M L → M L with 1 ⩽ L ⩽ 4 (i.e., the dipole, quadrupole, octupole and hexadecapole ones), the electric-to-magnetic cross-susceptibilities α E L → M(L - 1) with 2 ⩽ L ⩽ 5 and α E L → M(L + 1) with 1 ⩽ L ⩽ 4, the magnetic-to-electric cross-susceptibilities χ M L → E(L - 1) with 2 ⩽ L ⩽ 5 and χ M L → E(L + 1) with 1 ⩽ L ⩽ 4 (it holds that χ M L → E(L ∓ 1) =α E(L ∓ 1) → M L), and the electric-to-toroidal-magnetic cross-susceptibilities α E L → T L with 1 ⩽ L ⩽ 4. Numerical values are computed from general exact analytical formulas, derived by us elsewhere within the framework of the Dirac relativistic quantum mechanics, and involving generalized hypergeometric functions 3F2 of the unit argument.

  10. Magnetic susceptibility application : A window onto ancient environments and climatic variations: Foreword

    NARCIS (Netherlands)

    Da Silva, Anne Christine; Whalen, M. T.; Hladil, J.; Chadimova, L.; Chen, D.; Spassov, S.; Boulvain, F.; Devleeschouwer, X.

    2015-01-01

    Magnetic susceptibility (MS) is a powerful tool, which is being applied increasingly on sedimentary rocks to constrain stratigraphic correlations, or as a palaeo-environmental or palaeo-climatic tool. The origin of the magnetic minerals responsible for the variations in MS can be linked to various

  11. Magnetic susceptibility application : A window onto ancient environments and climatic variations: Foreword

    NARCIS (Netherlands)

    Da Silva, Anne Christine; Whalen, M. T.; Hladil, J.; Chadimova, L.; Chen, D.; Spassov, S.; Boulvain, F.; Devleeschouwer, X.

    2015-01-01

    Magnetic susceptibility (MS) is a powerful tool, which is being applied increasingly on sedimentary rocks to constrain stratigraphic correlations, or as a palaeo-environmental or palaeo-climatic tool. The origin of the magnetic minerals responsible for the variations in MS can be linked to various p

  12. Experimental and theoretical investigations of the magnetic susceptibility and anisotropy of Nd(OH)3

    Science.gov (United States)

    Karmakar, S.

    1985-08-01

    Measurements are reported on the magnetic susceptibilities and anisotropies of single crystals of Nd(OH)3 in the temperature range between 300 and 77 K. The intermediate-coupling scheme with J mixing under the crystal field of C3h symmetry is used to obtain the crystal-field energy levels and their eigenfunctions. Matrix elements of the Coulomb, spin-orbit, and crystal-field interactions within the f3 configuration are calculated. The g values are found to be g=3.65+/-0.01 and g⊥=1.95+/-0.01 in close agreement with the experimental values quoted by P. D. Scott (Ph.D. dissertation, Yale University, 1970). The calculated crystal-field splitting explains successfully the temperature dependence of the specific heat as observed by Chirico and Westrum [J. Chem. Thermodyn. 12, 311 (1980)] in the temperature range between 350 and 20 K. Saturated magnetizations parallel and perpendicular to the applied magnetic field are found to be 271 and 145 emu/cm3, respectively.

  13. Wave Vector Dependent Susceptibility at T>Tc in a Dipolar Ising Ferromagnet

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Holmes, L. M:; Guggenheim, H. J.

    1974-01-01

    The wave-vector-dependent susceptibility of LiTbF4 has been investigated by means of neutron scattering. The observations show a singularity of the susceptibility near wave vector Q=0 which is characteristic of the dipolar Coulomb interaction and good agreement with theory is obtained...

  14. Pressure Dependence of the Magnetization in the Ferromagnetic Superconductor UGe2

    Science.gov (United States)

    Pfleiderer, C.; Huxley, A. D.

    2002-09-01

    We report measurements of the pressure dependence of the low-temperature magnetization that show that the two pressure induced magnetic transitions in UGe2 are of first order. Further, the pressure dependence of the uniform susceptibility relative to the superconducting transition is not as expected if the latter is driven by the proximity to a ferromagnetic quantum critical point. Our data instead suggest that the superconducting pairing could be associated with a sharp spike in the electronic density of states that is also responsible for the lower pressure magnetic transition.

  15. Calculation of susceptibility through multiple orientation sampling (COSMOS): a method for conditioning the inverse problem from measured magnetic field map to susceptibility source image in MRI.

    Science.gov (United States)

    Liu, Tian; Spincemaille, Pascal; de Rochefort, Ludovic; Kressler, Bryan; Wang, Yi

    2009-01-01

    Magnetic susceptibility differs among tissues based on their contents of iron, calcium, contrast agent, and other molecular compositions. Susceptibility modifies the magnetic field detected in the MR signal phase. The determination of an arbitrary susceptibility distribution from the induced field shifts is a challenging, ill-posed inverse problem. A method called "calculation of susceptibility through multiple orientation sampling" (COSMOS) is proposed to stabilize this inverse problem. The field created by the susceptibility distribution is sampled at multiple orientations with respect to the polarization field, B(0), and the susceptibility map is reconstructed by weighted linear least squares to account for field noise and the signal void region. Numerical simulations and phantom and in vitro imaging validations demonstrated that COSMOS is a stable and precise approach to quantify a susceptibility distribution using MRI.

  16. Three-dimensional analysis of magnetic susceptibility in areas with different type of land use

    Science.gov (United States)

    Zawadzki, Jarosław; Fabijańczyk, Piotr

    2015-04-01

    The knowledge of the type of semivariance and its parameters such as nugget-effect, range of correlation and sill, that quantitatively characterize spatial variability of a studied environmental phenomenon, can be essential for both measurements planning and analysis of results. In particular this is the truth in the case of magnetometric measurements of soil pollution. Field magnetometry is internationally recognized as valuable, convenient and affordable tool for soil pollution screening and assessment. However, this geophysical method usually requires support of detailed statistical and geostatistical analyses. The goal of this study was to evaluate the parameters of spatial variability of soil magnetic susceptibility depending on the terrain usage. To do so, several types of study area were specially selected: forest, arable field and urban park. Some of the study areas were neighboring to each other, in order to ensure that the anthropogenic pressure was the same at each site. In order to analyze soil magnetic susceptibility in 3-dimensional space, measurements were performed on the soil surface and in soil profile, using the MS2D and MS2C Bartington instruments, respectively. MS2D measurements were performed using quasi-regular grids, and at each sample point 10 single MS2D readings were carried out in the circle with the diameter of about 2 meters. MS2C measurements were performed using soil cores collected in the field, down to the depth of about 30cm. Such approach combines the advantages of both types of measurements and allows to get deeper insight into the distribution of soil pollution. As the first step of the analysis, the semivariances of magnetic susceptibility were calculated and thoroughly modeled for all different forms of land use, on the basis of only the MS2D measurements. Then, the MS2D and MS2C measurements were jointed into one three-dimensional data set, and were used together to calculate and model the semivariances. Finally, the

  17. RHIC susceptibility to variations in systematic magnetic harmonic errors

    Energy Technology Data Exchange (ETDEWEB)

    Dell, G.F.; Peggs, S.; Pilat, F.; Satogata, T.; Tepikian, S.; Trbojevic, D.; Wei, J.

    1994-08-01

    Results of a study to determine the sensitivity of tune to uncertainties of the systematic magnetic harmonic errors in the 8 cm dipoles of RHIC are reported. Tolerances specified to the manufacturer for tooling and fabrication can result in systematic harmonics different from the expected values. Limits on the range of systematic harmonics have been established from magnet calculations, and the impact on tune from such harmonics has been established.

  18. Magnetic Susceptibility Analysis of Soil Affected by Hydrocarbon in Wonocolo Traditional Oil Field, Indonesia

    Science.gov (United States)

    Ulfah, Melianna; Wijatmoko, Bambang; Fitriani, Dini

    2017-04-01

    Magnetic susceptibility of soil affected by hydrocarbon was studied through cored soil samples in two zones (Zone One and Zone Two) of an oil field in Wonocolo Village, East Java. We also collected soil samples as the background from a residential area near the oil field (Zone Three). The Zone One, consisted two cores near producing well; the Zone Two consisted two cores obtained from near a dry hole well and a discontinued well; and the Zone Three consisted two cores to validate the initial soil magnetic susceptibility value in this area. The hydrocarbon content measurement was also done for the upper part of each cores using distillation method to identify the correlation between magnetic susceptibility and hydrocarbon content. From magnetic susceptibility measurement in dual frequency, samples from the Zone One and Zone Two have magnetic susceptibility range from 6,1 × 10-8 m3kg-1 - 160 × 10-8 m3kg-1 and 15,7 × 10-8 m3kg-1 - 417,9 × 10-8 m3kg-1, respectively. Whereas background samples from Zone Three have magnetic susceptibility range from 4,8 × 10-8 m3kg-1 to 81,1 × 10-8 m3kg-1. We found low χfd (%) in samples with high magnetic susceptibility values, shown that there was no indication of superparamagnetic minerals in the samples. The hydrocarbon content measurement shows the value range of 8% - 14% only exists in the upper part of all cores in Zone One and one core in Zone Two. From this analysis, we assume that other than the volume of the hydrocarbon content in soil, the period of petroleum hydrocarbon deposition in soil and the fossil fuel combustion generated in the study site could differently increase the soil magnetic susceptibility value in this area. Positive correlation between the two parameters hopefully could contribute to develop environmental magnetic methods for detecting oil spills in soil, especially to remediate former hydrocarbon exploration and production area.

  19. Micromagnetic susceptometer for the measurement of the magnetic susceptibility of the actinides

    Energy Technology Data Exchange (ETDEWEB)

    Nave, S. E.

    1979-08-01

    A device with the sensitivity for measuring the magnetic susceptibility of small volume samples (10/sup -7/ cm/sup 3/) as a function of temperature from 4.2K to 300K is described as designed specifically for measurements with microgram or submicrogram quantities of the actinide metals. Specifically, results are given for the susceptibility of curium-248 in the temperature range from 4.2K to 300K.

  20. Relationship between Magnetic Susceptibility and Heavy Metals Concentration in Polluted Soils of Lenjanat Region, Isfahan

    Directory of Open Access Journals (Sweden)

    Salehi M. H.

    2013-04-01

    Full Text Available This study analyzed the relationship between soil magnetic susceptibility and the content of Cd, Cu, Ni, and Fe on 233 samples from polluted soils of Lenjanat Region in the Isfahan. The aim was to investigate the suitability of such measurements for indicating heavy metal pollution. Heavy metal contents were determined after extraction with nitric acid. Basic soil characteristics were determined using common methods. Geochemical analysis of soil samples showed close correlation between Cd, Ni and Fe. Cd concentration was the highest of all the elements studied. The correlation between the analyzed metals and magnetic susceptibility are positive and significant for Fe and Cu. Results suggests that magnetic susceptibility can be used as a guideline to find contaminated urban areas with Fe and Cu in this region.

  1. Susceptibility effects in nuclear magnetic resonance imaging; Suszeptibilitaetseffekte in der Kernspinresonanzbildgebung

    Energy Technology Data Exchange (ETDEWEB)

    Ziener, Christian Herbert

    2008-07-01

    The properties of dephasing and the resulting relaxation of the magnetization are the basic principle on which all magnetic resonance imaging methods are based. The signal obtained from the gyrating spins is essentially determined by the properties of the considered tissue. Especially the susceptibility differences caused by magnetized materials (for example, deoxygenated blood, BOLD-effect) or magnetic nanoparticles are becoming more important for biomedical imaging. In the present work, the influence of such field inhomogeneities on the NMR-signal is analyzed. (orig.)

  2. Comparison between theory and simulations for the magnetization and the susceptibility of polydisperse ferrofluids.

    Science.gov (United States)

    Szalai, I; Nagy, S; Dietrich, S

    2013-11-20

    The influence of polydispersity on the magnetization of ferrofluids is studied based on a previously published magnetization equation of state (Szalai and Dietrich, 2011 J. Phys.: Condens. Matter 23 326004) and computer simulations. The polydispersity of the particle diameter is described by the gamma distribution function. Canonical ensemble Monte Carlo simulations have been performed in order to test these theoretical results for the initial susceptibility and the magnetization. The results for the magnetic properties of the polydisperse systems turn out to be in quantitative agreement with our present simulation data. In addition, we find good agreement between our theory and experimental data for magnetite-based ferrofluids.

  3. D.C. electrical conductivity and magnetic susceptibility of polythiophene doped with iodine

    Science.gov (United States)

    Chourasia, Ashish B.; Kelkar, Deepali S.

    2013-06-01

    Polythiophene was chemically synthesized, undoped and then re-doped with iodine. FTIR spectra confirm iodine doping. XRD analysis is used to calculate crystallinity of the samples. Electrical conductivity measurements were carried out using two probe technique in the temperature range from 300 K to 373 K. Undoped and doped samples show semi conducting nature. After doping the conductivity increases by eight orders of magnitude at 318 K. Magnetic susceptibility measurements were carried out using Guoy's method, both samples show diamagnetic nature. Conductivity and magnetic susceptibility measurements indicate that predominant charge carriers, in the iodine doped polythiophene, are bipolarons.

  4. Magnetic susceptibility of Al2RE compounds in crystal and liquid states

    Institute of Scientific and Technical Information of China (English)

    N.S. Uporova; S.A. Uporov; V.E. Sidorov

    2011-01-01

    Magnetic susceptibility of Al2RE (RE=Y,Ce,Sm,Gd,Dy,Ho,Yb) compounds was studied experimentally in wide temperature (T=290-2000 K) and field (B=0.3-1.3 T) intervals.The abnormal increase in susceptibility beginning above the melting point was fixed for all the compositions.The values for the effective magnetic moments per RE atoms in these compounds were found to be smaller than the values typical for free ions RE3+.The results were discussed in supposition of the directed bonds between aluminum and rare-earth atoms.

  5. Low-temperature magnetic susceptibility of concentrated ferrofluids: The influence of polydispersity

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Alexey O., E-mail: Alexey.Ivanov@usu.ru; Elfimova, Ekaterina A.

    2015-01-15

    In this paper we address the question of theoretical explanation of extremely high low-temperature initial magnetic susceptibility of concentrated ferrofluids. These laboratory synthesized samples [A.F. Pshenichnikov, A.V. Lebedev, J. Chem. Phys. 121(11) (2004) 5455; Colloid J. 67(2) (2005) 189] demonstrated the record-breaking values χ∼120–150 at temperatures ∼ 230–240 K. The existing models predict such high susceptibility only under the assumption of unreasonably large dipolar coupling constant, which is out of the range of applicability. Here we calculate the second virial contribution to susceptibility for polydisperse ferrofluid, modeled by the dipolar hard sphere fluid. In the resulting expression there exists the parameter, which plays a part of dipolar coupling constant and which is defined in a form of double averaging of high powers of particle sizes over the granulometric distribution. For real particle size distribution this effective parameter at least twice exceeds the commonly defined polydisperse dipolar coupling constant. We show that the low-temperature magnetic susceptibility of the record-breaking ferrofluids could be explained theoretically on the basis of the first terms of the polydisperse second virial contribution in combination with the second-order modified mean field model. - Highlights: • Record-breaking magnetic susceptibility of ferrofluids at low temperatures. • Second virial contribution to magnetic susceptibility of polydisperse ferrofluids. • Interparticle dipole correlations are more pronounced in dense ferrofluids. • Presented model describes the ferrofluid susceptibility χ∼120 at temperature 240 K.

  6. Effects of Size, deGennes and Ginzburg-Landau Parameters on the Magnetic Susceptibility of an Isotropic Superconductor

    Science.gov (United States)

    Aguirre, C. A.; González, J. D.; Barba-Ortega, J.

    2016-01-01

    The magnetic signature of a nanoscopic superconductor immersed in a magnetic applied field H_e is calculated numerically. The calculated magnetic susceptibility partial M / partial H_e of a superconducting nanoprism shows discontinuities and a quasiperiodic modulation at the vortex transition fields H_T (fields for which one or several vortices enter/leave the sample). In this contribution, we studied the influence of the sample size, the Ginzburg-Landau parameter κ and the deGennes parameter b on the magnetic susceptibility in a type-II isotropic superconductor. We found distinct signatures of the magnetic susceptibility when superconducting samples of two and three dimensions are considered.

  7. AC susceptibility as a tool to probe the dipolar interaction in magnetic nanoparticles

    OpenAIRE

    Landi, Gabriel T.; Arantes, Fabiana R; Cornejo, Daniel R.; Bakuzis, Andris F.; Andreu, Irene; Natividad, Eva

    2016-01-01

    The dipolar interaction is known to substantially affect the properties of magnetic nanoparticles. This is particularly important when the particles are kept in a fluid suspension or packed inside nano-carriers. In addition to its usual long-range nature, in these cases the dipolar interaction may also induce the formation of clusters of particles, thereby strongly modifying their magnetic anisotropies. In this paper we show how AC susceptibility may be used to obtain important information re...

  8. Spin-glass-like behaviour in ball milled Fe{sub 30}Cr{sub 70} alloy studied by ac magnetic susceptibility

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Blanco, D.; Gorria, P. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Fernandez-Martinez, Alejandro [Lawrence Livermore National Laboratory 7000 East Avenue, Livermore, CA 9455 (United States); Perez, M.J. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Cuello, Gabriel J. [Institut Laue-Langevin, BP 156, 6, rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Blanco, J.A., E-mail: jabr@uniovi.es [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain)

    2011-06-15

    Research highlights: > Spin-glass-like behaviour o owing an re-entrant spin-glass transition. > No critical divergence observed in the maxima of the real and magnetic susceptibility on ball milled Fe{sub 30}Cr{sub 70}. > High temperature Curie-Weiss behavior of the magnetic susceptibility on ball milled Fe{sub 30}Cr{sub 70}. > Moderate shift of the freezing temperature per frequency in ball milled Fe{sub 30}Cr{sub 70} obtained from the temperature dependence of the real magnetic susceptibility - Abstract: Nominal nanostructured Fe{sub 30}Cr{sub 70} obtained from ball milling during 110 h has been investigated from dc magnetization and ac magnetic susceptibility. The as-milled sample is not monophasic and is formed of two phases, Fe{sub 20{+-}2}Cr{sub 80{+-}2} ({approx}86 {+-} 2%) and iron ({approx}14 {+-} 2%). The ac susceptibility measurements show evidence of a re-entrant spin-glass-like transition for the Fe{sub 20}Cr{sub 80} phase below 30 K. The shift of the freezing temperature per frequency decade is moderate when compared to that found in conventional spin-glass alloys. A Vogel-Fulcher activation process can be used to explain the frequency variation. The results are also analyzed in terms of Cole-Cole formalism for extracting information of relaxation time ({tau} {approx} 10{sup -5} to 10{sup -4} s).

  9. Obtaining the magnetic susceptibility of the heme complex from DFT calculations

    Science.gov (United States)

    Pereira, L. M. O.; Resende, S. M.; Leite Alves, H. W.

    2016-09-01

    Magnetic field interactions with particles, as observed in magnetophoresis, are becoming important tool to understand the nature of the iron role in heme molecular complex, besides other useful applications. Accurate estimations of some macroscopic magnetic properties from quantum mechanical calculations, such as the magnetic susceptibility, can also check the reliability of the heme microscopic models. In this work we report, by using the Stoner criterion, a simple way to obtain the magnetic susceptibility of the heme complex from Density Functional Theory calculations. Some of our calculated structural properties and electronic structure show good agreement with both the available experimental and theoretical data, and the results show that its groundstate is a triplet 3A state. From the obtained results, we have evaluated the exchange interaction energy, J = 0.98 eV, the associated magnetic energy gain, Δ EM =-0.68 eV, and the magnetic susceptibility, χ0=1.73 ×10-6 cm3/mol for the heme alone (with uncompleted Fe ligands). If we consider the heme complex with the two histidine residues (completing the Fe ligands), we have then obtained χ0=5.27 ×10-12 cm3/g, which is in good agreement with experimental magnetophoresis data.

  10. Obtaining the magnetic susceptibility of the heme complex from DFT calculations

    Directory of Open Access Journals (Sweden)

    L. M. O. Pereira

    2016-09-01

    Full Text Available Magnetic field interactions with particles, as observed in magnetophoresis, are becoming important tool to understand the nature of the iron role in heme molecular complex, besides other useful applications. Accurate estimations of some macroscopic magnetic properties from quantum mechanical calculations, such as the magnetic susceptibility, can also check the reliability of the heme microscopic models. In this work we report, by using the Stoner criterion, a simple way to obtain the magnetic susceptibility of the heme complex from Density Functional Theory calculations. Some of our calculated structural properties and electronic structure show good agreement with both the available experimental and theoretical data, and the results show that its groundstate is a triplet 3A state. From the obtained results, we have evaluated the exchange interaction energy, J = 0.98 eV, the associated magnetic energy gain, ΔEM=−0.68 eV, and the magnetic susceptibility, χ0=1.73×10−6 cm3/mol for the heme alone (with uncompleted Fe ligands. If we consider the heme complex with the two histidine residues (completing the Fe ligands, we have then obtained χ0=5.27×10−12 cm3/g, which is in good agreement with experimental magnetophoresis data.

  11. Multifractal magnetic susceptibility distribution models of hydrothermally altered rocks in the Needle Creek Igneous Center of the Absaroka Mountains, Wyoming

    Science.gov (United States)

    Gettings, M.E.

    2005-01-01

    Magnetic susceptibility was measured for 700 samples of drill core from thirteen drill holes in the porphyry copper-molybdenum deposit of the Stinkingwater mining district in the Absaroka Mountains, Wyoming. The magnetic susceptibility measurements, chemical analyses, and alteration class provided a database for study of magnetic susceptibility in these altered rocks. The distribution of the magnetic susceptibilities for all samples is multi-modal, with overlapping peaked distributions for samples in the propylitic and phyllic alteration class, a tail of higher susceptibilities for potassic alteration, and an approximately uniform distribution over a narrow range at the highest susceptibilities for unaltered rocks. Samples from all alteration and mineralization classes show susceptibilities across a wide range of values. Samples with secondary (supergene) alteration due to oxidation or enrichment show lower susceptibilities than primary (hypogene) alteration rock. Observed magnetic susceptibility variations and the monolithological character of the host rock suggest that the variations are due to varying degrees of alteration of blocks of rock between fractures that conducted hydrothermal fluids. Alteration of rock from the fractures inward progressively reduces the bulk magnetic susceptibility of the rock. The model introduced in this paper consists of a simulation of the fracture pattern and a simulation of the alteration of the rock between fractures. A multifractal model generated from multiplicative cascades with unequal ratios produces distributions statistically similar to the observed distributions. The reduction in susceptibility in the altered rocks was modelled as a diffusion process operating on the fracture distribution support. The average magnetic susceptibility was then computed for each block. For the purpose of comparing the model results with observation, the simulated magnetic susceptibilities were then averaged over the same interval as the

  12. Multifractal magnetic susceptibility distribution models of hydrothermally altered rocks in the Needle Creek Igneous Center of the Absaroka Mountains, Wyoming

    Directory of Open Access Journals (Sweden)

    M. E. Gettings

    2005-01-01

    Full Text Available Magnetic susceptibility was measured for 700 samples of drill core from thirteen drill holes in the porphyry copper-molybdenum deposit of the Stinkingwater mining district in the Absaroka Mountains, Wyoming. The magnetic susceptibility measurements, chemical analyses, and alteration class provided a database for study of magnetic susceptibility in these altered rocks. The distribution of the magnetic susceptibilities for all samples is multi-modal, with overlapping peaked distributions for samples in the propylitic and phyllic alteration class, a tail of higher susceptibilities for potassic alteration, and an approximately uniform distribution over a narrow range at the highest susceptibilities for unaltered rocks. Samples from all alteration and mineralization classes show susceptibilities across a wide range of values. Samples with secondary (supergene alteration due to oxidation or enrichment show lower susceptibilities than primary (hypogene alteration rock. Observed magnetic susceptibility variations and the monolithological character of the host rock suggest that the variations are due to varying degrees of alteration of blocks of rock between fractures that conducted hydrothermal fluids. Alteration of rock from the fractures inward progressively reduces the bulk magnetic susceptibility of the rock. The model introduced in this paper consists of a simulation of the fracture pattern and a simulation of the alteration of the rock between fractures. A multifractal model generated from multiplicative cascades with unequal ratios produces distributions statistically similar to the observed distributions. The reduction in susceptibility in the altered rocks was modelled as a diffusion process operating on the fracture distribution support. The average magnetic susceptibility was then computed for each block. For the purpose of comparing the model results with observation, the simulated magnetic susceptibilities were then averaged over the same

  13. Temperature dependence of the magnetization of canted spin structures

    DEFF Research Database (Denmark)

    Jacobsen, Henrik; Lefmann, Kim; Brok, Erik;

    2012-01-01

    Numerous studies of the low-temperature saturation magnetization of ferrimagnetic nanoparticles and diamagnetically substituted ferrites have shown an anomalous temperature dependence. It has been suggested that this is related to freezing of canted magnetic structures. We present models for the ......Numerous studies of the low-temperature saturation magnetization of ferrimagnetic nanoparticles and diamagnetically substituted ferrites have shown an anomalous temperature dependence. It has been suggested that this is related to freezing of canted magnetic structures. We present models...

  14. The AC multi-harmonic magnetic susceptibility measurement setup at the LNF-INFN

    CERN Document Server

    Wang, Shenghao; Di Gioacchino, Daniele; Wu, Ziyu

    2014-01-01

    The AC magnetic susceptibility is a fundamental method in materials science, which allows to probe the dynamic magnetic response of magnetic materials and superconductors. The LAMPS laboratory at the Laboratori Nazionali di Frascati of the INFN hosts an AC multi-harmonic magnetometer that allows performing experiments with an AC magnetic field ranging from 0.1 to 20 Gauss and in the frequency range from 17 to 2070 Hz. A DC magnetic field from 0 to 8 T produced by a superconducting magnet can be applied, while data may be collected in the temperature range 4.2-300 K using a liquid He cryostat under different temperature cycles setups. The first seven AC magnetic multi-harmonic susceptibility components can be measured with a magnetic sensitivity of 1x10-6 emu and a temperature precision of 0.01 K. Here we will describe in detail about schematic of the magnetometer, special attention will be dedicated to the instruments control, data acquisition framework and the user-friendly LabVIEW-based software platform.

  15. 3D linear inversion of magnetic susceptibility data acquired by frequency domain EMI

    Science.gov (United States)

    Thiesson, J.; Tabbagh, A.; Simon, F.-X.; Dabas, M.

    2017-01-01

    Low induction number EMI instruments are able to simultaneously measure a soil's apparent magnetic susceptibility and electrical conductivity. This family of dual measurement instruments is highly useful for the analysis of soils and archeological sites. However, the electromagnetic properties of soils are found to vary over considerably different ranges: whereas their electrical conductivity varies from ≤ 0.1 to ≥ 100 mS/m, their relative magnetic permeability remains within a very small range, between 1.0001 and 1.01 SI. Consequently, although apparent conductivity measurements need to be inverted using non-linear processes, the variations of the apparent magnetic susceptibility can be approximated through the use of linear processes, as in the case of the magnetic prospection technique. Our proposed 3D inversion algorithm starts from apparent susceptibility data sets, acquired using different instruments over a given area. A reference vertical profile is defined by considering the mode of the vertical distributions of both the electrical resistivity and of the magnetic susceptibility. At each point of the mapped area, the reference vertical profile response is subtracted to obtain the apparent susceptibility variation dataset. A 2D horizontal Fourier transform is applied to these variation datasets and to the dipole (impulse) response of each instrument, a (vertical) 1D inversion is performed at each point in the spectral domain, and finally the resulting dataset is inverse transformed to restore the apparent 3D susceptibility variations. It has been shown that when applied to synthetic results, this method is able to correct the apparent deformations of a buried object resulting from the geometry of the instrument, and to restore reliable quantitative susceptibility contrasts. It also allows the thin layer solution, similar to that used in magnetic prospection, to be implemented. When applied to field data it initially delivers a level of contrast

  16. Magnetic susceptibility at zero and nonzero chemical potential in QCD and QED

    CERN Document Server

    Orlovsky, V D

    2014-01-01

    Magnetic susceptibility of the quark matter in QCD is calculated in a closed form for an arbitrary chemical potential \\mu. For small \\mu, \\mu T^2, the oscillations as functions of eB occur, characteristic of the de Haas-van Alphen effect. Results are compared with available lattice data.

  17. Magnetic susceptibility in the deep layers of the primary motor cortex in Amyotrophic Lateral Sclerosis

    Directory of Open Access Journals (Sweden)

    M. Costagli

    2016-01-01

    Full Text Available Amyotrophic Lateral Sclerosis (ALS is a progressive neurological disorder that entails degeneration of both upper and lower motor neurons. The primary motor cortex (M1 in patients with upper motor neuron (UMN impairment is pronouncedly hypointense in Magnetic Resonance (MR T2* contrast. In the present study, 3D gradient-recalled multi-echo sequences were used on a 7 Tesla MR system to acquire T2*-weighted images targeting M1 at high spatial resolution. MR raw data were used for Quantitative Susceptibility Mapping (QSM. Measures of magnetic susceptibility correlated with the expected concentration of non-heme iron in different regions of the cerebral cortex in healthy subjects. In ALS patients, significant increases in magnetic susceptibility co-localized with the T2* hypointensity observed in the middle and deep layers of M1. The magnetic susceptibility, hence iron concentration, of the deep cortical layers of patients' M1 subregions corresponding to Penfield's areas of the hand and foot in both hemispheres significantly correlated with the clinical scores of UMN impairment of the corresponding limbs. QSM therefore reflects the presence of iron deposits related to neuroinflammatory reaction and cortical microgliosis, and might prove useful in estimating M1 iron concentration, as a possible radiological sign of severe UMN burden in ALS patients.

  18. Magnetic susceptibility in the deep layers of the primary motor cortex in Amyotrophic Lateral Sclerosis.

    Science.gov (United States)

    Costagli, M; Donatelli, G; Biagi, L; Caldarazzo Ienco, E; Siciliano, G; Tosetti, M; Cosottini, M

    2016-01-01

    Amyotrophic Lateral Sclerosis (ALS) is a progressive neurological disorder that entails degeneration of both upper and lower motor neurons. The primary motor cortex (M1) in patients with upper motor neuron (UMN) impairment is pronouncedly hypointense in Magnetic Resonance (MR) T2* contrast. In the present study, 3D gradient-recalled multi-echo sequences were used on a 7 Tesla MR system to acquire T2*-weighted images targeting M1 at high spatial resolution. MR raw data were used for Quantitative Susceptibility Mapping (QSM). Measures of magnetic susceptibility correlated with the expected concentration of non-heme iron in different regions of the cerebral cortex in healthy subjects. In ALS patients, significant increases in magnetic susceptibility co-localized with the T2* hypointensity observed in the middle and deep layers of M1. The magnetic susceptibility, hence iron concentration, of the deep cortical layers of patients' M1 subregions corresponding to Penfield's areas of the hand and foot in both hemispheres significantly correlated with the clinical scores of UMN impairment of the corresponding limbs. QSM therefore reflects the presence of iron deposits related to neuroinflammatory reaction and cortical microgliosis, and might prove useful in estimating M1 iron concentration, as a possible radiological sign of severe UMN burden in ALS patients.

  19. Magnetic Susceptibility as a Proxy for Investigating Microbial Mediated Iron Reduction

    Science.gov (United States)

    We investigated magnetic susceptibility (MS) variations in hydrocarbon contaminated sediments. Our objective was to determine if MS can be used as an intrinsic bioremediation indicator due to the activity of iron-reducing bacteria. A contaminated and an uncontaminated core were r...

  20. Anisotropic magnetic susceptibility of erbium and ytterbium in zircon, ZrSiO4

    Science.gov (United States)

    Thorpe, A.N.; Briggs, Charles; Tsang, T.; Senftle, F.; Alexander, Corrine

    1977-01-01

    Magnetic susceptibility measurements have been made for both Er- and Yb-doped (1̃03ppm) zircon single crystals with the magnetic field perpendicular and parallel to the [001] axis. Large susceptibility anisotropies were found in both cases. Our observed anisotropies of ZrSiO4: Yb indicate small populations (1̃9%) of Yb ions at the axial (tetragonal) sites, as the susceptibility of ZrSiO4: Yb would be nearly isotropic if the Yb ions only occupied the orthorhombic sites. For Er3+ in orthorhombic sites of zircon, our data indicate that the first excited state is paramagnetic with gx = 9 and gy 5̃ at 20 cm-1 above the ground state (gx 0̃, gy 1̃5). The first excited state is quite similar to the ground states observed for Er3+ in many host lattices. ?? 1977.

  1. Magnetic field induced third order susceptibility of third order harmonic generation in a ZnMgSe strained quantum well

    Energy Technology Data Exchange (ETDEWEB)

    Mark, J. Abraham Hudson, E-mail: a.john.peter@gmail.com; Peter, A. John, E-mail: a.john.peter@gmail.com [Dept. of Physics, SSM Institute of Engineering and Technology, Dindigul-624002 (India)

    2014-04-24

    Third order susceptibility of third order harmonic generation is investigated in a Zn{sub 0.1}Mg{sub 0.9}Se/Zn{sub 0.8}Mg{sub 0.2}Se/Zn{sub 0.1}Mg{sub 0.9}Se quantum well in the presence of magnetic field strength. The confinement potential is considered as the addition of energy offsets of the conduction band (or valence band) and the strain-induced potential in our calculations. The material dependent effective mass is followed throughout the computation because it has a high influence on the electron energy levels in low dimensional semiconductor systems.

  2. Magnetoresistance, susceptibility and magnetization measurements on RNiBC compounds (R = Er, Ho, Dy, Tb, and Gd)

    Science.gov (United States)

    Tróchez, J. C.; Sánchez, D. R.; Giordanengo, B.; Fontes, M. B.; Continentino, Múcio; Baggio-Saitovitch, E. M.

    1997-08-01

    We studied magnetic behavior of the RNiBC compounds by magnetic and transport measurements. At low temperatures, each compound has different magnetic structure. Magnetoresistivity data are in good accordance with theory of magnetic elementary interactions, susceptibility reveals the magnetic transition and Curie Weiss behavior and magnetization shows low value of the saturation compared with the free R+3 ion that confirm that crystalline electric field is strong as in the RNi2B2C series.

  3. Global Lithospheric Apparent Susceptibility Distribution Converted from Geomagnetic Models by CHAMP and Swarm Satellite Magnetic Measurements

    Science.gov (United States)

    Du, Jinsong; Chen, Chao; Xiong, Xiong; Li, Yongdong; Liang, Qing

    2016-04-01

    Recently, because of continually accumulated magnetic measurements by CHAMP satellite and Swarm constellation of three satellites and well developed methodologies and techniques of data processing and geomagnetic field modeling etc., global lithospheric magnetic anomaly field models become more and more reliable. This makes the quantitative interpretation of lithospheric magnetic anomaly field possible for having an insight into large-scale magnetic structures in the crust and uppermost mantle. Many different approaches have been utilized to understand the magnetized sources, such as forward, inversion, statistics, correlation analysis, Euler deconvolution, signal transformations etc. Among all quantitative interpretation methods, the directly converting a magnetic anomaly map into a magnetic susceptibility anomaly map proposed by Arkani-Hamed & Strangway (1985) is, we think, the most fast quantitative interpretation tool for global studies. We just call this method AS85 hereinafter for short. Although Gubbins et al. (2011) provided a formula to directly calculate the apparent magnetic vector distribution, the AS85 method introduced constraints of magnetized direction and thus corresponding results are expected to be more robust especially in world-wide continents. Therefore, in this study, we first improved the AS85 method further considering non-axial dipolar inducing field using formulae by Nolte & Siebert (1987), initial model or priori information for starting coefficients in the apparent susceptibility conversion, hidden longest-wavelength components of lithospheric magnetic field and field contaminations from global oceanic remanent magnetization. Then, we used the vertically integrated susceptibility model by Hemant & Maus (2005) and vertically integrated remanent magnetization model by Masterton et al. (2013) to test the validity of our improved method. Subsequently, we applied the conversion method to geomagnetic field models by CHAMP and Swarm satellite

  4. In situ measurement of alternating current magnetic susceptibility of Pd-hydrogen system for determination of hydrogen concentration in bulk.

    Science.gov (United States)

    Akamaru, Satoshi; Hara, Masanori; Matsuyama, Masao

    2012-07-01

    An alternating current magnetic susceptometer for use as a hydrogen gauge for hydrogen-storage materials was designed and developed. The experimental system can simultaneously measure the hydrogen equilibrium pressure and the magnetic susceptibility of metal hydrides. The background voltage of the susceptometer was stabilized for a long period of time, without any adjustments, by attaching an efficient compensation circuit. The performance of the susceptometer at a static hydrogen concentration was demonstrated by measuring the magnetic susceptibility of a Pd-hydrogen system under equilibrium conditions. The in situ measurement of the magnetic susceptibility of Pd during hydrogen absorption was carried out using the susceptometer. Since the in situ magnetic susceptibility obtained at a lower initial hydrogen pressure agreed with the magnetic susceptibility measured at a static hydrogen concentration, the susceptometer could be used to determine the hydrogen concentration in Pd in situ. At a higher initial hydrogen pressure, enhancement of the magnetic susceptibility was observed at the beginning of hydrogen absorption because the magnetic moments induced by the large temporary strain generated in the Pd affected the magnetic susceptibility.

  5. Magnetic susceptibility and magnetoresistance of neutron-irradiated doped SI whiskers

    Energy Technology Data Exchange (ETDEWEB)

    Druzhinin, A.A., E-mail: druzh@polynet.lviv.ua [Lviv Polytechnic National University, S. Bandera Str., 12, Lviv 79013 (Ukraine); International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw (Poland); Ostrovskii, I.P.; Khoverko, Yu.M. [Lviv Polytechnic National University, S. Bandera Str., 12, Lviv 79013 (Ukraine); International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw (Poland); Rogacki, K. [International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw (Poland); Litovchenko, P.G.; Pavlovska, N.T. [Institute of Nuclear Researches, NAS of Ukraine, 47, Prospect Nauky, 03028 Kyiv (Ukraine); Pavlovskyy, Yu.V.; Ugrin, Yu.O. [Ivan Franko Drohobych State Pedagogical University, 24, Franko str., 82100 Drohobych (Ukraine)

    2015-11-01

    The effect of 8.6·10{sup 17} n/cm{sup 2} fast neutron irradiation on the magnetic susceptibility and magnetoresistance of Si whiskers with impurity concentration near metal–insulator transition (MIT) has been studied. Neutron irradiated specimens with boron concentration away of MIT are mainly diamagnetic with a small amount of paramagnetic centers originated from dangling bonds on the whisker surface. It has been established that at temperatures near 4.2 K, a significant contribution to the conductivity is made by light charge carriers of low concentration but with high mobility. The as grown whiskers with impurity concentration correspondent to MIT showed hysteresis loops in magnetization at temperature of liquid helium. Besides hysteresis loops in magnetoresistance was observed for whiskers under compression stress at low temperature up to 7 K. The possible reason of the effect can be magnetic interaction between impurities centers in subsurface region of the whisker with the orbital moment of dangle bounds in the whisker core–shell interstices. - Highlights: • Neutron irradiation influence on magnetic susceptibility of Si whiskers is studied. • Neutron irradiated Si whiskers with boron concentration away of MIT are diamagnetic. • Whiskers in the vicinity to MIT showed hysteresis loops in magnetoresistance. • Whiskers in the vicinity to MIT showed hysteresis loops in magnetic susceptibility.

  6. Can the magnetic susceptibility record of Chinese Red Clay sequence be used for palaeomonsoon reconstructions?

    Science.gov (United States)

    Zhao, Guoyong; Han, Yan; Liu, Xiuming; Chang, Liao; Lü, Bin; Chen, Qu; Guo, Xuelian; Yan, Junhui; Yan, Jun

    2016-03-01

    Red Clay underlying the loess-palaeosol sequences on the Chinese Loess Plateau is an eolian deposit. There is a controversy over whether magnetic susceptibility (χ) variations in Red Clay sequence can be used as an indicator of summer palaeomonsoon intensity. This study investigates the magnetic mineralogy, magnetic concentration and magnetic grain size distribution of Jiaxian Red Clay with multimagnetic methods. Our results indicate that the magnetic properties of Jiaxian Red Clay are similar to those of the Quaternary loess-palaeosol sequences, and ultrafine ferrimagnetic grains produced during pedogenesis are responsible for an increase in susceptibility, therefore the χ enhancement mechanism of Red Clay is similar to that of the overlying loess-palaeosol sequences. This paper explores χ variations in the Red Clay sequence through spatial and temporal analysis. The susceptibility variation of six sites along a NNE to SSW transect correlate to palaeoclimatic cycles, so χ can be used to trace the summer palaeomonsoon intensity from a spatial perspective. However, a simple loess-derived calibration function cannot be used to quantitative reconstruct the palaeomonsoon intensity variations thought time. An adjusted calibration function for palaeosols from Red Clay sequence needs to be developed, so that χ can be used to quantitative reconstruct palaeomonsoon intensity. Further study is necessary to develop such a transfer function.

  7. Mapping soil erosion using magnetic susceptibility. A case study in Ukraine

    Directory of Open Access Journals (Sweden)

    P. Nazarok

    2014-03-01

    Full Text Available The intrinsic element grouping of the magnetic susceptibility (MS values is conducted. The relation between MS values and erosion index is shown. The objective of the investigation is study of the information about magnetic susceptibility of soils as a diagnostic criterion to erodibility. The investigations were conducted in the limits of Tcherkascy Tishki territory, Kharkiv district. The soils of the territory are presented by catenary row of chernozems. The study area was used in the field crop rotation. The soil conservation technologies have not been applied. The data analyze confirmed high correlation of the MS, erosive index and humus content. The possibility of MS cartogram using at the soil erodibility map is presented. The magnetic methods can be extensively used at the soil erosion investigations thanks to the speed and low cost.

  8. The complex initial reluctivity, permeability and susceptibility spectra of magnetic materials

    Science.gov (United States)

    Hamilton, N. C.

    2015-03-01

    The HF complex permeability spectrum of a magnetic material is deduced from the measured impedance spectrum, which is then normalized to a series permeability spectrum. However, this series permeability spectrum has previously been shown to correspond to a parallel magnetic circuit, which is not appropriate. Some of the implications of this truth are examined. This electric/magnetic duality has frustrated efforts to interpret the shape of the complex magnetic permeability spectra of materials, and has hindered the application of impedance spectroscopy to magnetic materials. In the presence of magnetic loss, the relationship between the relative magnetic permeability and the magnetic susceptibility is called into question. The use of reluctivity spectra for expressing magnetic material properties is advocated. The relative loss factor, tanδm/μi is shown to be an approximation for the imaginary part of the reluctivity. A single relaxation model for the initial reluctivity spectra of magnetic materials is presented, and its principles are applied to measurements of a high permeability ferrite. The results are presented as contour plots of the spectra as a function of temperature.

  9. Environmental mechanism of magnetic susceptibility changes of lacustrine sediments from Lake Hulun, China

    Institute of Scientific and Technical Information of China (English)

    胡守云; 王苏民; Erwin; Appel; 吉磊

    2000-01-01

    The changes of magnetic susceptibility (κ) are correlated with those of corresponding sedimentological, geochemical, mineralogical and biological results, which verifies that κ can be taken as one of the environmental proxies. However, usually the exact origin of magnetic signal is poorly understood, and is difficult to relate with the environmental evolution. Magnetic properties of material derived from the catchment and sedimentary environment may affect the accumulation, preservation, or authigenesis and diagenesis of magnetic minerals. In the Lake Hulun region in Inner Mongolia, it is found that muddy sediments, deposited during high water level period (corresponding to humid climate), have comparatively high κ values. In contrast, the sandy sediments, deposited during low water level period (corresponding to arid climate), have low κ values. Detailed rock magnetic investigation confirms that detrital magnetite derived from volcanic rocks in the catchment exists in both muddy and sandy sediments

  10. Very high field magnetization and AC susceptibility of native horse spleen ferritin

    Energy Technology Data Exchange (ETDEWEB)

    Guertin, R.P. [Department of Physics and Astronomy, Room 201, Science and Technology Center, Tufts University, Medford, MA 02155 (United States)]. E-mail: robert.guertin@tufts.edu; Harrison, N. [National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Zhou, Z.X. [MS6056, Oak Ridge National Laboratory, Oak Ridge, TN 37830 (United States); McCall, S. [Lawrence Livermore National Laboratory, PO Box 808, Livermore, CA 94551 (United States); Drymiotis, F. [Department of Physics and Astronomy, Clemson University, Clemson, SC 29634 (United States)

    2007-01-15

    The magnetization of native horse spleen ferritin protein is measured in pulsed magnetic fields to 55 T at T=1.52 K. The magnetization rises smoothly with negative curvature due to uncompensated Fe{sup 3+} spins and with a large high field slope due to the underlying antiferromagnetic ferritin core. Even at highest fields the magnetic moment is only {approx}4% of the saturation moment of the full complement of Fe{sup 3+} in the ferritin molecule. The AC magnetic susceptibility, {chi} {sub AC}(T,f), responding to the uncompensated spins, reaches a maximum near the superparamagnetic blocking temperature with the temperature of the maximum, T {sub M}, varying with excitation frequency, T {sub M} {sup -1} {alpha} log f for 10{<=}f{<=}10{sup 4} Hz.

  11. Signal changes in cortical laminar necrosis - evidence from susceptibility-weighted magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kesavadas, Chandrasekharan; Santhosh, Kannath; Thomas, Bejoy; Gupta, Arun Kumar; Kapilamoorthy, Tirur Raman; Bodhey, Narendra; Pendharker, Hima; Patro, Satyanarayana [Sree Chitra Tirunal Institute for Medical Sciences and Technology, Department of Imaging Sciences and Interventional Radiology, Trivandrum (India)

    2009-05-15

    Two types of infarcts can be identified depending on the circumstances leading to its generation-infarcts with pannecrosis and infarcts with selective neuronal loss. Cortical laminar necrosis (CLN) can occur due to various etiologies of which infarctions and hypoxia are the commonest. Infarction results in pannecrosis whereas hypoxia and incomplete infarction result in selective neuronal loss with the presence of viable cells, glial proliferations, and deposition of paramagnetic substances. We investigated patients with CLN with susceptibility-weighted imaging (SWI), a technique highly sensitive to even traces of paramagnetic agents or hemorrhagic components. We retrospectively reviewed medical records of patients diagnosed with CLN as per standard criterion. Demographic characteristics and etiologies were recorded. Findings in magnetic resonance images including SWI were analyzed. We identified 11 patients with CLN, six males and five females with age range of 4-64 years. Etiologies included hypoxia in two patients and infarction in the nine patients. SWI detected diffuse linear hypointensities along the gyral margins in CLN due to hypoxic ischemic encephalopathy. Linear dot like hypointensities were identified in one patient with infarction. CLN due to hypoxic ischemic encephalopathy display linear gyral hypointensities and basal ganglia hypointensities that are identifiable in SWI and may represent mineralization. This might be related to iron transport across the surviving neurons from basal ganglia to the cortex, which is not possible in complete infarction. SWI may be helpful in understanding the pathophysiological aspects of CLN due to complete infarction and hypoxia. (orig.)

  12. Lyapunov functions and global stability for SIR and SEIR models with age-dependent susceptibility

    KAUST Repository

    Korobeinikov, Andrei

    2013-01-01

    We consider global asymptotic properties for the SIR and SEIR age structured models for infectious diseases where the susceptibility depends on the age. Using the direct Lyapunov method with Volterra type Lyapunov functions, we establish conditions for the global stability of a unique endemic steady state and the infection-free steady state.

  13. Lyapunov functions and global stability for SIR and SEIR models with age-dependent susceptibility.

    Science.gov (United States)

    Melnik, Andrey V; Korobeinikov, Andrei

    2013-04-01

    We consider global asymptotic properties for the SIR and SEIR age structured models for infectious diseases where the susceptibility depends on the age. Using the direct Lyapunov method with Volterra type Lyapunov functions, we establish conditions for the global stability of a unique endemic steady state and the infection-free steady state.

  14. Field Dependence, Efficiency of Information Processing in Working Memory and Susceptibility to Orientation Illusions among Architects

    Directory of Open Access Journals (Sweden)

    Młyniec Agnieszka

    2016-04-01

    Full Text Available This study examined cognitive predictors of susceptibility to orientation illusions: Poggendorff, Ponzo, and Zöllner. It was assumed that lower efficiency of information processing in WM and higher field dependence are conducive to orientation illusions. 61 architects (30 women aged M = 29, +/- 1.6, and 49 university students (29 women aged M = 23.53, +/- 4.24, were tested with Witkin’s EFT to assess their field dependence; the SWATT method was used as a measure of WM efficiency, and susceptibility to visual illusions was verified with a series of computer tasks. We obtained a small range of the explained variance in the regression models including FDI and WM indicators. On the basis of WM efficiency indicators, we managed to confirm the existence of memory predictors of susceptibility to illusions (they are rather weak, as they explain from 6% to 14% of the variance of the dependent variable. Among the architects, lower efficiency of WM processing (weaker inhibition, task-switching and higher field dependence are responsible for greater susceptibility to orientation illusions.

  15. Non-perturbative treatment of molecules in linear magnetic fields: calculation of anapole susceptibilities.

    Science.gov (United States)

    Tellgren, Erik I; Fliegl, Heike

    2013-10-28

    In the present study a non-perturbative approach to ab initio calculations of molecules in strong, linearly varying, magnetic fields is developed. The use of London atomic orbitals (LAOs) for non-uniform magnetic fields is discussed and the standard rationale of gauge-origin invariance is generalized to invariance under arbitrary constant shifts of the magnetic vector potential. Our approach is applied to study magnetically induced anapole moments (or toroidal moments) and the related anapole susceptibilities for a test set of chiral and nonchiral molecules. For the first time numerical anapole moments are accessible on an ab initio level of theory. Our results show that the use of London atomic orbitals dramatically improves the basis set convergence also for magnetic properties related to non-uniform magnetic fields, at the cost that the Hellmann-Feynman theorem does not apply for a finite LAO basis set. It is shown that the mixed anapole susceptibility can be related to chirality, since its trace vanishes for an achiral molecule.

  16. Application of Anisotropy of Magnetic Susceptibility to large-scale fault kinematics: an evaluation

    Science.gov (United States)

    Casas, Antonio M.; Roman-Berdiel, Teresa; Marcén, Marcos; Oliva-Urcia, Belen; Soto, Ruth; Garcia-Lasanta, Cristina; Calvin, Pablo; Pocovi, Andres; Gil-Imaz, Andres; Pueyo-Anchuela, Oscar; Izquierdo-Llavall, Esther; Vernet, Eva; Santolaria, Pablo; Osacar, Cinta; Santanach, Pere; Corrado, Sveva; Invernizzi, Chiara; Aldega, Luca; Caricchi, Chiara; Villalain, Juan Jose

    2017-04-01

    Major discontinuities in the Earth's crust are expressed by faults that often cut across its whole thickness favoring, for example, the emplacement of magmas of mantelic origin. These long-lived faults are common in intra-plate environments and show multi-episodic activity that spans for hundred of million years and constitute first-order controls on plate evolution, favoring basin formation and inversion, rotations and the accommodation of deformation in large segments of plates. Since the post-Paleozoic evolution of these large-scale faults has taken place (and can only be observed) at shallow crustal levels, the accurate determination of fault kinematics is hampered by scarcely developed fault rocks, lack of classical structural indicators and the brittle deformation accompanying fault zones. These drawbacks are also found when thick clayey or evaporite levels, with or without diapiric movements, are the main detachment levels that facilitate large displacements in the upper crust. Anisotropy of Magnetic Susceptibility (AMS) provides a useful tool for the analysis of fault zones lacking fully developed kinematic indicators. However, its meaning in terms of deformational fabrics must be carefully checked by means of outcrop and thin section analysis in order to establish the relationship between the orientation of magnetic ellipsoid axes and the transport directions, as well as the representativity of scalar parameters regarding deformation mechanisms. Timing of faulting, P-T conditions and magnetic mineralogy are also major constraints for the interpretation of magnetic fabrics and therefore, separating ferro- and para-magnetic fabric components may be necessary in complex cases. AMS results indicate that the magnetic lineation can be parallel (when projected onto the shear plane) or perpendicular (i.e. parallel to the intersection lineation) to the transport direction depending mainly on the degree of shear deformation. Changes between the two end-members can

  17. Identification of Heavy Metal Pollution Derived From Traffic in Roadside Soil Using Magnetic Susceptibility.

    Science.gov (United States)

    Yang, Pingguo; Ge, Jing; Yang, Miao

    2017-06-01

    The study integrates surface and vertical distribution of magnetic susceptibility and heavy metal contents (Pb, Cu, Zn and Fe) to characterize the signature of vehicle pollutants in roadside soils at Linfen city, China. Sites with reforestation and without vegetation cover were investigated. The results showed that magnetic susceptibility and heavy metal contents were higher at the roadside without trees than in the reforest belt. The variations of magnetic susceptibility and heavy metal contents decreased both with distance and with depth. The maximum value was observed at 5-10 m away from the roadside edge. The vertical distribution in soil revealed accumulation of pollutants in 0-5 cm topsoils. The average contents were higher than the background values and in the order Fe (107.21 g kg(-1)), Zn (99.72 mg kg(-1)), Pb (90.99 mg kg(-1)), Cu (36.14 mg kg(-1)). Coarse multi domain grains were identified as the dominating magnetic particles. Multivariate statistical and SEM/EDX analyses suggested that the heavy metals derived from traffic sources. Trees act as efficient receptors and green barrier, which can reduce vehicle derived pollution.

  18. Magnetic shielding and exotic spin-dependent interactions

    CERN Document Server

    Kimball, D F Jackson; Li, Y; Thulasi, S; Pustelny, S; Budker, D; Zolotorev, M

    2016-01-01

    Experiments searching for exotic spin-dependent interactions typically employ magnetic shielding between the source of the exotic field and the interrogated spins. We explore the question of what effect magnetic shielding has on detectable signals induced by exotic fields. Our general conclusion is that for common experimental geometries and conditions, magnetic shields should not significantly reduce sensitivity to exotic spin-dependent interactions, especially when the technique of comagnetometry is used. However, exotic fields that couple to electron spin can induce magnetic fields in the interior of shields made of a soft ferro- or ferrimagnetic material. This induced magnetic field must be taken into account in the interpretation of experiments searching for new spin-dependent interactions and raises the possibility of using a flux concentrator inside magnetic shields to amplify exotic spin-dependent signals.

  19. The Physical Property of Susceptibility for One-Dimensional Ferrimagnetic Chain with Alternating Spins 1 and 1/2 in Finite Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    XIE Gang; HAN Ru-Shan

    2001-01-01

    We further calculate the dependence of xT on T in high magnetic fields,where X denotes susceptibility and T is temperature,using our previous research work - Green function's decoupling approximate approach,for the one-dimensional ferrimagnetic chain with alternating spins 1 and 1/2.We find a linear correlation in certain range of magnetic field between the temperature of xT maximum and the magnetic field.Moreover,we simply analyze its physical meaning by our approach.``

  20. Exploring the Magnetic Susceptibility of a Haldane Compound Sm2BaNiO5: Optical Spectroscopy of Sm^{3+} Kramers Doublets

    Science.gov (United States)

    Galkin, A. S.; Klimin, S. A.

    2016-12-01

    An optical spectroscopic study of quasi-Haldane chain nickelate Sm2BaNiO5 is presented. A temperature-dependent splitting of the ground-state Kramers doublet of the Sm^{3+} ion due to an antiferromagnetic ordering at TN = 55 K has been obtained experimentally and used to calculate the Schottky-type anomaly in magnetic susceptibility. The value of the magnetic moment of Sm^{3+} ion at zero temperature has been estimated within the model of the ground doublet. One-dimensional magnetic behavior of the nickel subsystem is emphasized.

  1. Frequency and Magnetic Field Dependence of the Skin Depth in Co-rich Soft Magnetic Microwires

    Directory of Open Access Journals (Sweden)

    A. Zhukov

    2016-11-01

    Full Text Available We studied giant magnetoimpedance (GMI effect in magnetically soft amorphous Co-rich microwires in the extended frequency range. From obtained experimentally dependences of GMI ratio on magnetic field and different frequencies we estimated the penetration depth and its dependence on applied magnetic field and frequency

  2. Rotational dynamics of magnetic silica spheres studied by measuring the complex magnetic susceptibility

    NARCIS (Netherlands)

    Claesson, E.M.; Erne, B.H.; Philipse, A.P.

    2007-01-01

    The weak permanent magnetic dipole moment of cobalt ferrite-doped colloidal silica spheres was increased by exposure to a saturating magnetic field. The resulting change of the rotational dynamics of the magnetic microspheres in a weak alternating field was measured from low to high volume fraction

  3. Spatial variability of soil magnetic susceptibility in an agricultural field located in Eastern Ukraine

    Science.gov (United States)

    Menshov, Oleksandr; Pereira, Paulo; Kruglov, Oleksandr

    2015-04-01

    .05 MS×10-9 m3/kg, and a minimum and a maximum value of 499.33 and 862.27 MS×10-9 m3/kg respectively. The standard deviation was 85.62 and the coefficient of variation 12.48%. This shows that the spatial variability of soil MS was low. The Global Morans I index was of 0.841, a z-score of 7.741 with a psoil MS had a clustered pattern. The variogram results showed that the gaussian model was the the best fitted. The nugget effect was 0.1007. the sill 0.9905 and the nugget/sill ratio of 0.10, which shows that soil MS has a strong spatial dependency. The results of the interpolation tests showed that the errors distribution followed the normal distribution, the average predicted values were similar to the observed and the correlation between these two distributions was high (between 0.85-0.90) in all the cases. The method that predicted better soil MS was LP2 and the less accurate was SK. Soil MS presented high values in the southwestern part and low in the northeast area of the plot. It is clearly observed a increase of soil MS from the top of the slope to the bottom. Acknowledgments RECARE (Preventing and Remediating Degradation of Soils in Europe Through Land Care, FP7-ENV-2013-TWO STAGE), funded by the European Commission; and for the COST action ES1306 (Connecting European connectivity research). References Boyko, T., Scholger, R., Stanjek, H., MAGPROX team (2004) Topsoil magnetic suseptibility mapping as a tool for pollution monitoring: Repetability of in situ measurments. Journal of Applied Geophysics, 55, 249-259. Dankoub, Z., Ayoubi, S., Khademi, H., Sheng-Gao, L. (2012) Spatial distribution of magnetic properties and selected heavy metals in calcareous soils as affected by land use in the Isfahan Region, Central Iran. Pedosphere, 22, 33-47. Girault, F., Poitou, C., Perrier, F., Koirala, B.P., Bhattarai, M. (2011) Soil characterization using patterns of magnetic susceptibility versus effective radimu concentration. Natural Hazards Earth System Science, 11, 2285

  4. [Susceptibility weighted magnetic resonance sequences "SWAN, SWI and VenoBOLD": technical aspects and clinical applications].

    Science.gov (United States)

    Hodel, J; Rodallec, M; Gerber, S; Blanc, R; Maraval, A; Caron, S; Tyvaert, L; Zuber, M; Zins, M

    2012-05-01

    Susceptibility-weighted MR sequences, T2 star weighted angiography (SWAN, General Electric), Susceptibility weighted imaging (SWI, Siemens) and venous blood oxygen level dependant (VenoBOLD, Philips) are 3D spoiled gradient-echo sequence that provide a high sensitivity for the detection of blood degradation products, calcifications, and iron deposits. For all these sequences, an appropriate echo time allows for the visualization of susceptibility differences between adjacent tissues. However, each of these sequences presents a specific technical background. The purpose of this review was to describe 1/the technical aspects of SWAN, VenoBOLD and SWI sequences, 2/the differences observed in term of contrast within the images, 3/the key imaging findings in neuroimaging using susceptibility-weighted MR sequences.

  5. Magnetic susceptibility and its relationship with paleoenvironments, diagenesis and remagnetization: examples from the Devonian carbonates of Belgium

    NARCIS (Netherlands)

    Da Silva, A.-C.; Dekkers, M.J.; Mabille, C.; Boulvain, F.

    2012-01-01

    To better understand the origin of the initial magnetic susceptibility (χin) signal in carbonate sequences, a rock magnetic investigation that includes analysis of acquisition curves of the isothermal remanent magnetization (IRM) and hysteresis parameters, was undertaken on Devonian carbonates from

  6. Anisotropies of anhysteretic remanence and magnetic susceptibility of marly clays from Central Italy

    Directory of Open Access Journals (Sweden)

    L. Sagnotti

    1994-06-01

    Full Text Available Marly clays from an Upper Pliocene unit at Valle Ricca (Rorne were investigated for their Anisotropy of Anhysteretic Remanence (AAR and Anisotropy of Magnetic Susceptibility (AMS. The study of AAR was accomplished for the first time in ltaly, developing a suitable laboratory technique and adapting a standard statistical procedure. The comparison between anhysteretic remanence and magnetic susceptibility anisotropies discriminates the fabric of the ferromagnetic fraction from that of the paramagnetic matrix of the rock. The separation of fabric components was applied to distinguish subsequent geological processes that affected the total rock fabric. The results indicate that the clayey units are particularly suitable for the empirical investigation of fabric to strain relationship in weakly deformed rocks.

  7. Temperature dependence of microwave oscillations in magnetic tunnel junctions with a perpendicularly magnetized free layer

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Peng; Feng, Jiafeng, E-mail: hxwei@iphy.ac.cn, E-mail: jiafengfeng@iphy.ac.cn; Wei, Hongxiang, E-mail: hxwei@iphy.ac.cn, E-mail: jiafengfeng@iphy.ac.cn; Han, Xiufeng [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Fang, Bin; Zhang, Baoshun; Zeng, Zhongming [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Ruoshui Road 398, Suzhou 215123 (China)

    2015-01-05

    We experimentally study the temperature dependence of the spin-transfer-torque-induced microwave oscillations in MgO-based magnetic tunnel junction nanopillars with a perpendicularly magnetized free layer. We demonstrate that the oscillation frequency increases rapidly with decreasing temperature, which is mainly ascribed to the temperature dependence of both the saturation magnetization and the perpendicular magnetic anisotropy. We also find that a strong temperature dependence of the output power while a nonmonotonic temperature dependence of spectral linewidth are maintained for a constant dc bias in measured temperature range. Possible mechanisms leading to the different dependences of oscillation frequency, output power, and linewidth are discussed.

  8. Reinvestigation of superconducting phase diagram of UGe{sub 2} by AC magnetic susceptibility experiment

    Energy Technology Data Exchange (ETDEWEB)

    Ban, S. [Deptartment of Physics, University of Nagoya, Nagoya, 464-8602 (Japan)]. E-mail: f060214d@mbox.nagoya-u.ac.jp; Deguchi, K. [Deptartment of Physics, University of Nagoya, Nagoya, 464-8602 (Japan); Aso, N. [Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581 (Japan); Homma, Y. [Oarai Branch, Inst. for Mater. Research, University of Tohoku, Ibaraki 311-1313 (Japan); Shiokawa, Y. [Oarai Branch, Inst. for Mater. Research, University of Tohoku, Ibaraki 311-1313 (Japan); Sato, N.K. [Deptartment of Physics, University of Nagoya, Nagoya, 464-8602 (Japan)

    2007-03-15

    We report a superconducting phase diagram of the ferromagnetic superconductor UGe{sub 2} investigated by AC magnetic susceptibility measurements. In contrast to previous phase diagrams, we found that the superconducting transition temperature and volume fraction show a 'M-shaped' structure as a function of pressure. From this observation, we suggest that both of two critical points will play a crucial role in the occurrence of superconductivity in UGe{sub 2}.

  9. Magnetic susceptibility, transport properties, XPS and electronic structure of UCoGa{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Morkowski, J.A. E-mail: jmorkows@ifmpan.poznan.pl; Szajek, A.; Bukowski, Z.; Sulkowski, C.; Troc, R.; Chelkowska, G

    2004-05-01

    Monocrystals of the tetragonal compound UCoGa{sub 5} were grown. Magnetic susceptibility, electrical resistivity and thermoelectric power were measured both along the tetragonal c-axis and in the perpendicular direction. The electronic band structure was calculated by the tight-binding linear muffin-tin orbitals method in the atomic sphere approximation, with spin-orbit interactions taken into account. The X-ray photoemission spectrum was measured and calculated with a satisfactory agreement.

  10. Test of magnetic susceptibility and grain-size age models of loess

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Ages of the stratigraphic boundary MIS1/2 and MIS3/4 of the Yuanbu loess section in Linxia are used as the basis of the nodal control age. The age of MIS1/2 and MIS3/4 are obtained from the latest international research result-the climatic events recorded in the stalagmite in the Hulu Cave in Nanjing, that MIS1/2 is 11.5 kaB. P. and MIS3/4 is 59.8 kaB.P.. The ages of the two climatic events contain three nodal age control models (Model 1: 0 kaB. P. -59.8 kaB. P.; Model 2: 0 kaB. P. -11.5 kaB. P. and 11.5kaB. P. -59.8 kaB. P.; Model 3: 11.5 kaB. P. -59.8 kaB. P. ), which are used as the nodal control age separately. The deposition times of various stratigraphic horizons are calculated by using the magnetic susceptibility age model and grain-size age model, and then compared with each other. In addition, the AMS14C age, OSL age and the ages of YD and H events are compared with the ages of the corresponding horizons calculated by the three models of nodal control ages. From the analyses of lithologic characters and climatic stages it has been found that both the magnetic susceptibility age model and the grain-size age model have some defects. Because the accurate control ages are selected as the nodal points of the glacial period or interglacial period, the stratigraphic deposition times determined by the high resolution of magnetic susceptibility age model and grain-size age model approximate to the actual ages. As for the relative accuracy of the two age models, the magnetic susceptibility age model is more accurate than the grain-size age model.

  11. Application of orthorhombic standardization in magnetic susceptibility studies of localized spin models with S=1, 3/2, 2, 5/2

    Energy Technology Data Exchange (ETDEWEB)

    Pełka, Robert, E-mail: Robert.Pelka@ifj.edu.pl [H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, E. Radzikowskiego 152, 31-342 Kraków (Poland); Rudowicz, Czesław [Faculty of Chemistry, A. Mickiewicz University, Umultowska 89B, 61-614 Poznań (Poland)

    2016-09-15

    The standardization idea is nowadays tacitly accepted in EMR area, however, its usefulness in magnetism studies has not been fully recognized as yet. This idea arises due to intrinsic features of orthorhombic Hamiltonians of any physical nature, including the crystal (ligand) field (CF/LF) Hamiltonians or the zero-field splitting (ZFS) ones. Standardization limits the ratio of the orthorhombic parameter to the axial one to a fixed range between 0 and a specific value that depends on the notation used. For the ZFS parameters expressed in the conventional spin Hamiltonian (SH) notation the ratio λ=E/D can always be limited to the range (0, ±1/3) by appropriate choice of coordinate system. Implications of standardization of orthorhombic spin Hamiltonians for interpretation of experimental magnetic susceptibility data are considered. Using a numerical example, we show the existence of alternative solutions for ZFS parameters potentially obtainable from fitting experimental magnetic data and discuss their importance. For the first time algebraic applications of the standardization to the expressions for magnetic susceptibility tensor derived earlier for localized spin models with S=1, 3/2, 2, 5/2 and with rhombic anisotropy are explored. The numerical and algebraic results allow us to formulate an 'invariance principle'. These considerations facilitate interpretation of experimental magnetic data and provide an additional check of correctness of analytical magnetic susceptibility expressions.

  12. Magnetic Susceptibility of Soil to Differentiate Soil Environments in Southern Brazil

    Directory of Open Access Journals (Sweden)

    Priscila Vogelei Ramos

    Full Text Available ABSTRACT The interest in new techniques to support digital soil mapping (DSM is increasing. Numerous studies pointed out that the measure of magnetic susceptibility (MS can be extremely useful in the identification of properties related with factors and processes of soil formation, applied to soil mapping. This study addressed the effectiveness of magnetic soil susceptibility to identify and facilitate the distinction of different pedogenic environments of a representative hillslope in the highland Planalto Médio in the state of Rio Grande do Sul (RS, Brazil. In a 350-ha area in the municipality of Santo Augusto, RS, a representative transect was selected, trenches opened for soil characterization and 29 grid points marked at regular distances of 50 m, where soil samples were collected (layers 0.00-0.05, 0.05-0.15, 0.15-0.30, and 0.30-0.60 m to analyze soil properties. Data from the transect samples were subjected to descriptive statistics. Limits of the pedogenetic environments along the slope were identified by the Split Moving Window (SMW Boundary Analysis. The combined use of soil magnetic susceptibility and the SMW technique was effective in identifying different pedogenetic environments in the study area.

  13. Polarized dependence of nonlinear susceptibility in a single layer graphene system in infrared region

    Science.gov (United States)

    Solookinejad, G.

    2016-09-01

    In this study, the linear and nonlinear susceptibility of a single-layer graphene nanostructure driven by a weak probe light and an elliptical polarized coupling field is discussed theoretically. The Landau levels of graphene can be separated in infrared or terahertz regions under the strong magnetic field. Therefore, by using the density matrix formalism in quantum optic, the linear and nonlinear susceptibility of the medium can be derived. It is demonstrated that by adjusting the elliptical parameter, one can manipulate the linear and nonlinear absorption as well as Kerr nonlinearity of the medium. It is realized that the enhanced Kerr nonlinearity can be possible with zero linear absorption and nonlinear amplification at some values of elliptical parameter. Our results may be having potential applications in quantum information science based on Nano scales devices.

  14. Polarized dependence of nonlinear susceptibility in a single layer graphene system in infrared region

    Energy Technology Data Exchange (ETDEWEB)

    Solookinejad, G., E-mail: ghsolooki@gmail.com

    2016-09-15

    In this study, the linear and nonlinear susceptibility of a single-layer graphene nanostructure driven by a weak probe light and an elliptical polarized coupling field is discussed theoretically. The Landau levels of graphene can be separated in infrared or terahertz regions under the strong magnetic field. Therefore, by using the density matrix formalism in quantum optic, the linear and nonlinear susceptibility of the medium can be derived. It is demonstrated that by adjusting the elliptical parameter, one can manipulate the linear and nonlinear absorption as well as Kerr nonlinearity of the medium. It is realized that the enhanced Kerr nonlinearity can be possible with zero linear absorption and nonlinear amplification at some values of elliptical parameter. Our results may be having potential applications in quantum information science based on Nano scales devices.

  15. Estimating the contribution of Brownian and Néel relaxation in a magnetic fluid through dynamic magnetic susceptibility measurements

    Energy Technology Data Exchange (ETDEWEB)

    Maldonado-Camargo, L. [Department of Chemical Engineering, University of Florida, Gainesville, FL 32611 (United States); Torres-Díaz, I. [J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611 (United States); Chiu-Lam, A. [Department of Chemical Engineering, University of Florida, Gainesville, FL 32611 (United States); Hernández, M. [J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611 (United States); Rinaldi, C., E-mail: carlos.rinaldi@bme.ufl.edu [Department of Chemical Engineering, University of Florida, Gainesville, FL 32611 (United States); J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611 (United States)

    2016-08-15

    We demonstrate how dynamic magnetic susceptibility measurements (DMS) can be used to estimate the relative contributions of Brownian and Néel relaxation to the dynamic magnetic response of a magnetic fluid, a suspension of magnetic nanoparticles. The method applies to suspensions with particles that respond through Brownian or Néel relaxation and for which the characteristic Brownian and Néel relaxation times are widely separated. First, we illustrate this using magnetic fluids consisting of mixtures of particles that relax solely by the Brownian or Néel mechanisms. Then, it is shown how the same approach can be applied to estimate the relative contributions of Brownian and Néel relaxation in a suspension consisting of particles obtained from a single synthesis and whose size distribution straddles the transition from Néel to Brownian relaxation. - Highlights: • Method to estimate the contributions of the relaxation mechanism to the magnetic response. • Method applies to cases where the Brownian and Néel peaks do not overlap. • The method applies for ferrofluids prepared with as–synthesized particles.

  16. Static magnetic susceptibility, crystal field and exchange interactions in rare earth titanate pyrochlores

    NARCIS (Netherlands)

    Malkin, B. Z.; Lummen, T. T. A.; van Loosdrecht, P. H. M.; Dhalenne, G.; Zakirov, A. R.

    2010-01-01

    The experimental temperature dependence (T = 2-300 K) of single crystal bulk and site susceptibilities of rare earth titanate pyrochlores R2Ti2O7 (R = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) is analyzed in the framework of crystal field theory and a mean field approximation. Analytical expressions for the s

  17. Preparation of novel bovine hemoglobin surface-imprinted polystyrene nanoparticles with magnetic susceptibility

    Institute of Scientific and Technical Information of China (English)

    LI Lin; HE XiWen; CHEN LangXing; ZHANG YuKui

    2009-01-01

    In this research,a surface imprinting strategy has been adopted in protein imprinting.Bovine hemoglobin surface-imprinted polystyrene (PS) nanoparticles with magnetic susceptibility have been synthesized through multistage core-shell polymerization system using 3-aminophenylboronic acid (APBA)as functional and cross-linking monomers.SuperparamagneUc molecularly imprinted polystyrene nanospheres with poly(APBA) thin films have been synthesized and used for the first time for protein molecular imprinting in an aqueous solution.The magnetic susceptibility is imparted through the successful encapsulation of Fe3O4 nanoparticles.The morphology,adsorption,and recognition properties of superparamagnetic molecularly imprinted polymers (MIPs) have been investigated using transmission electron microscopy,X-ray diffraction,thermogravimetric analysis,and vibrating sample magnetometer.Rebinding experimental results show that poly(APBA) MIPs-coated superparamagnetic PS nanoparticles have high adsorption capacity for template protein bovine hemoglobin and comparatively low nonspecific adsorption.The imprinted superparamagnetlc nanoparticles could easily reach the adsorption equilibrium and achieve magnetic separation in an external magnetic field,thus avoiding some problems of the bulk polymer.

  18. Preparation of novel bovine hemoglobin surface-imprinted polystyrene nanoparticles with magnetic susceptibility

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this research, a surface imprinting strategy has been adopted in protein imprinting. Bovine hemo-globin surface-imprinted polystyrene (PS) nanoparticles with magnetic susceptibility have been syn-thesized through multistage core-shell polymerization system using 3-aminophenylboronic acid (APBA) as functional and cross-linking monomers. Superparamagnetic molecularly imprinted polystyrene nanospheres with poly(APBA) thin films have been synthesized and used for the first time for protein molecular imprinting in an aqueous solution. The magnetic susceptibility is imparted through the successful encapsulation of Fe3O4 nanoparticles. The morphology, adsorption, and recognition prop-erties of superparamagnetic molecularly imprinted polymers (MIPs) have been investigated using transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, and vibrating sample magnetometer. Rebinding experimental results show that poly(APBA) MIPs-coated superparamagnetic PS nanoparticles have high adsorption capacity for template protein bovine hemoglobin and compara-tively low nonspecific adsorption. The imprinted superparamagnetic nanoparticles could easily reach the adsorption equilibrium and achieve magnetic separation in an external magnetic field, thus avoid-ing some problems of the bulk polymer.

  19. Quantum Size- Dependent Third- Order Nonlinear Optical Susceptibility in Semiconductor Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    SUN Ting; XIONG Gui-guang

    2005-01-01

    The density matrix approach has been employed to investigate the optical nonlinear polarization in a single semiconductor quantum dot(QD). Electron states are considered to be confined within a quantum dot with infinite potential barriers. It is shown, by numerical calculation, that the third-order nonlinear optical susceptibilities for a typical Si quantum dot is dependent on the quantum size of the quantum dot and the frequency of incident light.

  20. Light-dependent magnetic compass in Iberian green frog tadpoles

    Science.gov (United States)

    Diego-Rasilla, Francisco Javier; Luengo, Rosa Milagros; Phillips, John B.

    2010-12-01

    Here, we provide evidence for a wavelength-dependent effect of light on magnetic compass orientation in Pelophylax perezi (order Anura), similar to that observed in Rana catesbeiana (order Anura) and Notophthalmus viridescens (order Urodela), and confirm for the first time in an anuran amphibian that a 90° shift in the direction of magnetic compass orientation under long-wavelength light (≥500 nm) is due to a direct effect of light on the underlying magnetoreception mechanism. Although magnetic compass orientation in other animals (e.g., birds and some insects) has been shown to be influenced by the wavelength and/or intensity of light, these two amphibian orders are the only taxa for which there is direct evidence that the magnetic compass is light-dependent. The remarkable similarities in the light-dependent magnetic compasses of anurans and urodeles, which have evolved as separate clades for at least 250 million years, suggest that the light-dependent magnetoreception mechanism is likely to have evolved in the common ancestor of the Lissamphibia (Early Permian, ~294 million years) and, possibly, much earlier. Also, we discuss a number of similarities between the functional properties of the light-dependent magnetic compass in amphibians and blue light-dependent responses to magnetic stimuli in Drosophila melanogaster, which suggest that the wavelength-dependent 90° shift in amphibians may be due to light activation of different redox forms of a cryptochrome photopigment. Finally, we relate these findings to earlier studies showing that the pineal organ of newts is the site of the light-dependent magnetic compass and recent neurophysiological evidence showing magnetic field sensitivity in the frog frontal organ (an outgrowth of the pineal).

  1. Static magnetic susceptibility, crystal field and exchange interactions in rare earth titanate pyrochlores.

    Science.gov (United States)

    Malkin, B Z; Lummen, T T A; van Loosdrecht, P H M; Dhalenne, G; Zakirov, A R

    2010-07-14

    The experimental temperature dependence (T = 2-300 K) of single crystal bulk and site susceptibilities of rare earth titanate pyrochlores R(2)Ti(2)O(7) (R = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) is analyzed in the framework of crystal field theory and a mean field approximation. Analytical expressions for the site and bulk susceptibilities of the pyrochlore lattice are derived taking into account long range dipole-dipole interactions and anisotropic exchange interactions between the nearest neighbor rare earth ions. The sets of crystal field parameters and anisotropic exchange coupling constants have been determined and their variations along the lanthanide series are discussed.

  2. Environmental mechanism of magnetic susceptibility changes of lacustrine sediments from Lake Hulun, China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The changes of magnetic susceptibility (κ) are correlated with those of corresponding sedimentological, geochemical, mineralogical and biological results, which verifies that κ can be taken as one of the environmental proxies. However, usually the exact origin of magnetic signal is poorly understood, and is difficult to relate with the environmental evolution. Magnetic properties of material derived from the catchment and sedimentary environment may affect the accumulation, preservation, or authigenesis and diagenesis of magnetic minerals. In the Lake Hulun region in Inner Mongolia, it is found that muddy sediments, deposited during high water level period (corresponding to humid climate), have comparatively high κ values. In contrast, the sandy sediments, deposited during low water level period (corresponding to arid climate), have low κ values. Detailed rock magnetic investigation confirms that detrital magnetite derived from volcanic rocks in the catchment exists in both muddy and sandy sediments. During high water level period, secondary ferrimagnetic iron sulphide was produced in muddy sediments under relatively reductive conditions. Ferrimagnetic iron sulphide, coexisting with detrital magnetite, predominates the magnetic properties of muddy sediments, resulting in increasing κ. This paper reveals the significance of authigenic ferrimagnetic iron sulphide produced after sediment deposition.

  3. Dependence of the magnetization on the interface morphology in ultra-thin magnetic/non-magnetic films: Monte Carlo approach

    Energy Technology Data Exchange (ETDEWEB)

    Razouk, A. [Laboratoire de Physique et Mecanique des Materiaux, Faculte des Sciences et Techniques, Universite Sultan Moulay Slimane, BP 523, 23000 Beni-Mellal (Morocco); Sahlaoui, M., E-mail: msahlaoui@yahoo.fr [Laboratoire de Physique et Mecanique des Materiaux, Faculte des Sciences et Techniques, Universite Sultan Moulay Slimane, BP 523, 23000 Beni-Mellal (Morocco); Sajieddine, M. [Laboratoire de Physique et Mecanique des Materiaux, Faculte des Sciences et Techniques, Universite Sultan Moulay Slimane, BP 523, 23000 Beni-Mellal (Morocco)

    2009-07-30

    Using Monte Carlo simulations, we have studied the dependence of magnetic properties on interface morphology in magnetic/non-magnetic (M/NM) multilayers. Our aim is to relate macroscopic magnetic properties of the multilayers to their concentration profile at the interface. Our model consists of an alternate staking of magnetic and non-magnetic layers with disordered interfaces. We have considered different concentration and the existence of local magnetic domains at the interface. The results indicate the crucial dependence of magnetization amplitude with interface multilayers atomic composition and the spatial arrangement of magnetic atoms. In particular, we show that isolated islands at the interface leads to the apparition of super-paramagnetic behavior.

  4. The effect of pressure on the magnetic susceptibility of RInCu4 (R = Gd, Er and Yb)

    Science.gov (United States)

    Svechkarev, I. V.; Panfilov, A. S.; Dolja, S. N.; Nakamura, H.; Shiga, M.

    1999-06-01

    The magnetic susceptibility of the intermetallic compounds RInCu4 (R = Gd, Er and Yb) was measured under helium gas pressure up to 2 kbar at the fixed temperatures 78, 150 and 300 K. For YbInCu4, which exhibits a first-order valence phase transition at TVicons/Journals/Common/simeq" ALT="simeq" ALIGN="TOP"/>40 K, the Grüneisen parameter for the Kondo energy, icons/Journals/Common/Omega" ALT="Omega" ALIGN="TOP"/>Kicons/Journals/Common/equiv" ALT="equiv" ALIGN="TOP"/>-dlnTK/dlnV = -32, is large and typical for Ce-based heavy-fermion systems in magnitude but opposite in sign. The effect of atomic disorder is discussed on the basis of the data for a chemically disordered sample; the pressure effect at T = 78 K is strongly enhanced due to the spatial dispersion of pressure-sensitive TV, and hence dTV/dP = -2.0 K kbar-1 is obtained by assuming a Gaussian distribution of TV. On the basis of an extrapolation of the experimental pressure dependence, a (P,T) phase diagram is proposed for YbInCu4. Reference compounds with stable f moments, GdInCu4 and ErInCu4, show negligible pressure dependences of the susceptibility.

  5. Measurement of the magnetic field-dependent refractive index of magnetic fluids in bulk

    Institute of Scientific and Technical Information of China (English)

    Ting Liu; Xianfeng Chen; Ziyun Di; Junfeng Zhang; Xinwan Li; Jianping Chen

    2008-01-01

    An optical alignment-free and highly accurate method is employed to measure the magnetic field-dependent refractive index of magnetic fluid(MF) in bulk.The measured refractive index decreases significantly with the increasing magnetic strength and then tends to saturate in the high intensity range.By applying a tunable magnetic field ranging between 0 and 1661 Oe,the maximum shift of the refractive index of MF in bulk iS found to be 0.0231.

  6. Magnetic susceptibility of oxygen adsorbed on the surface of spherical and fibrous activated carbon.

    Directory of Open Access Journals (Sweden)

    Kiyoshi Kawamura

    2009-02-01

    Full Text Available The magnetic susceptibilities of oxygen adsorbed on the surface of bead-shaped activated carbon and activated carbon fibers were evaluated as a function of temperature between 4.2 K and 300 K, and found to exhibit a sharp peak at around 50 K. This implies that the adsorbed oxygen molecules form an antiferromagnetic state. The relation between the susceptibility and the adsorbed mass suggest that the thickness of the adsorbed oxygen is thin enough to consider a two-dimensional structure for bead–shaped activated carbon and carbon fibers across the fiber axis but thick enough to regard it as three-dimensional along the fiber axis. The result is discussed with reference to the study on one-dimensional oxygen array.

  7. No K/T boundary at Anjar, Gujarat, India: Evidence from magnetic susceptibility and carbon isotopes

    Indian Academy of Sciences (India)

    H J Hansen; D M Mohabey; P Toft

    2001-06-01

    The paper describes the variation pattern of magnetic susceptibility of Lameta sediments and isotopic variation of organic 13C from Chui Hill, Bergi, Kholdoda, Pisdura and Girad. The susceptibility pattern and a negative carbon isotopic anomaly allows fixation of the K/T boundary at these localities and they dier in these aspects from the inter-trappean sediments at Anjar. Paleomagnetic measurements of the Anjar sediment and the overlying basalt ow demonstrate reversed polarity. The Lameta sediments with dinosaur nests at Kheda and the overlying intertrappean sediments are of normal polarity The clay layers at Anjar, associated closely with Ir-enrichments, are strongly leached, rhyolitic bentonites containing low-quartz paramorphs after high-quartz with glass inclusions. It is concluded, that the inter-trappean lake deposits at Anjar were deposited in the early part of magnetochron 29R and are unrelated to the K/T boundary.

  8. Magnetic susceptibility of QCD at zero and at finite temperature from the lattice

    CERN Document Server

    Bali, G S; Constantinou, M; Costa, M; Endrodi, G; Katz, S D; Panagopoulos, H; Schaefer, A

    2012-01-01

    The response of the QCD vacuum to a constant external (electro)magnetic field is studied through the tensor polarization of the chiral condensate and the magnetic susceptibility at zero and at finite temperature. We determine these quantities using lattice configurations generated with the tree-level Symanzik improved gauge action and N_f=1+1+1 flavors of stout smeared staggered quarks with physical masses. We carry out the renormalization of the observables under study and perform the continuum limit both at T>0 and at T=0, using different lattice spacings. Finite size effects are studied by using various spatial lattice volumes. The magnetic susceptibilities \\chi_f reveal a diamagnetic behavior; we obtain at zero temperature \\chi_u=-(2.08 +/- 0.08) 1/GeV^2, \\chi_d=-(2.02 +/- 0.09) 1/GeV^2 and \\chi_s=-(3.4 +/- 1.4) 1/GeV^2 for the up, down and strange quarks, respectively, in the MSBar scheme at a renormalization scale of 2 GeV. We also find the polarization to change smoothly with the temperature in the con...

  9. Universal temperature dependence of the magnetization of gapped spin chains.

    Science.gov (United States)

    Maeda, Yoshitaka; Hotta, Chisa; Oshikawa, Masaki

    2007-08-03

    A Haldane chain under applied field is analyzed numerically, and a clear minimum of magnetization is observed as a function of temperature. We elucidate its origin using the effective theory near the critical field and propose a simple method to estimate the gap from the magnetization at finite temperatures. We also demonstrate that there exists a relation between the temperature dependence of the magnetization and the field dependence of the spin-wave velocity. Our arguments are universal for general axially symmetric one-dimensional spin systems.

  10. Structure, magnetic susceptibility, and specific heat of the spin-orbital-liquid candidate FeS c2S4 : Influence of Fe off-stoichiometry

    Science.gov (United States)

    Tsurkan, V.; Prodan, L.; Felea, V.; Filippova, I.; Kravtsov, V.; Günther, A.; Widmann, S.; Krug von Nidda, H.-A.; Deisenhofer, J.; Loidl, A.

    2017-08-01

    We report structure, susceptibility, and specific heat studies of stoichiometric and off-stoichiometric poly- and single crystals of the A -site spinel compound FeS c2S4 . In stoichiometric samples, no long-range magnetic order is found down to 1.8 K. The magnetic susceptibility of these samples is field independent in the temperature range 10-400 K and does not show irreversible effects at low temperatures. In contrast, the magnetic susceptibility of samples with iron excess shows substantial field dependence at high temperatures and manifests a pronounced magnetic irreversibility at low temperatures with a difference between zero-field cooled (ZFC) and field cooled (FC) susceptibilities and a maximum at 10 K, reminiscent of a magnetic transition. Single-crystal x-ray diffraction of the stoichiometric samples revealed a single phase spinel structure without site inversion. In single crystalline samples with Fe excess, in addition to the main spinel phase, a second ordered single-crystal phase was detected with the diffraction pattern of a vacancy-ordered superstructure of iron sulfide, close to the 5C polytype F e9S10 . Specific heat studies reveal a broad anomaly, which evolves below 20 K in both stoichiometric and off-stoichiometric crystals. We show that the low-temperature specific heat can be well described by considering the low-lying spin-orbital electronic levels of F e2 + ions. Our results demonstrate significant influence of excess Fe ions on intrinsic magnetic behavior of FeS c2S4 and provide support for the spin-orbital liquid scenario proposed in earlier studies for the stoichiometric compound.

  11. Design and development of novel MRI compatible zirconium- ruthenium alloys with ultralow magnetic susceptibility

    Science.gov (United States)

    Li, H. F.; Zhou, F. Y.; Li, L.; Zheng, Y. F.

    2016-04-01

    In the present study, novel MRI compatible zirconium-ruthenium alloys with ultralow magnetic susceptibility were developed for biomedical and therapeutic devices under MRI diagnostics environments. The results demonstrated that alloying with ruthenium into pure zirconium would significantly increase the strength and hardness properties. The corrosion resistance of zirconium-ruthenium alloys increased significantly. High cell viability could be found and healthy cell morphology observed when culturing MG 63 osteoblast-like cells and L-929 fibroblast cells with zirconium-ruthenium alloys, whereas the hemolysis rates of zirconium-ruthenium alloys are 316L stainless steel, Co–Cr alloys and Ti-based alloys, the magnetic susceptibilities of the zirconium-ruthenium alloys (1.25 × 10‑6 cm3·g‑1–1.29 × 10‑6 cm3·g‑1 for zirconium-ruthenium alloys) are ultralow, about one-third that of Ti-based alloys (Ti–6Al–4V, ~3.5 × 10‑6 cm3·g‑1, CP Ti and Ti–6Al–7Nb, ~3.0 × 10‑6 cm3·g‑1), and one-sixth that of Co–Cr alloys (Co–Cr–Mo, ~7.7 × 10‑6 cm3·g‑1). Among the Zr–Ru alloy series, Zr–1Ru demonstrates enhanced mechanical properties, excellent corrosion resistance and cell viability with lowest magnetic susceptibility, and thus is the optimal Zr–Ru alloy system as therapeutic devices under MRI diagnostics environments.

  12. A Model of Mercury's Magnetospheric Magnetic Field with Dependence on Magnetic Activity

    Science.gov (United States)

    Korth, H.; Tsyganenko, N. A.; Johnson, C. L.; Philpott, L. C.; Anderson, B. J.; Solomon, S. C.; McNutt, R. L., Jr.

    2015-12-01

    Accurate knowledge of Mercury's magnetospheric magnetic field is required to characterize the planet's internal field and the structure of the magnetosphere. We present the first model of Mercury's magnetospheric magnetic field that includes a dependence on magnetic activity. The model consists of individual modules for magnetic fields of internal origin, approximated by a dipole of magnitude 190 nT RM3, where RM is Mercury's radius, offset northward by 479 km along the spin axis, and of external origin resulting from currents flowing on the magnetopause boundary and in the cross-tail current sheet. The magnetic field is confined within a magnetopause shape derived from Magnetometer observations by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft and dependent on magnetic activity. The cross-tail current is prescribed having a disk shape near the planet and extending into a sheet at larger distances. The magnitude of the tail current, which also depends on magnetic activity, is fit to minimize the root-mean-square residual between the model magnetic field and the field within the magnetosphere observed by MESSENGER. The model was fit separately for magnetic field observations within distinct levels of magnetic activity. Linear fits of model parameters versus magnetic activity allows continuous scaling of the model to magnetic activity. The magnetic field contribution from each module is shielded individually by a scalar potential function, which was fit to minimize the root-mean-square normal magnetic field component at the magnetopause. The resulting model reproduces the dependence of the magnetospheric size and tail current intensity on magnetic activity, and allows more accurate characterization of the internal field.

  13. EPR and Magnetic Susceptibility Investigation of Fe Ions in B2O3-SrF2 Glass Matrix

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The structural and magnetic properties of an oxide-fluoride mixed vitreous matrix 2B2O3@SrF2, were explored by using Fe impurities as probes. Information about the structural units involving iron ions, their valence state, the strengths and type of interactions involving them was obtained using EPR spectroscopy and magnetic susceptibility measurements.

  14. Zero-temperature perturbative calculation of the magnetic susceptibility of the free fermion system

    Energy Technology Data Exchange (ETDEWEB)

    Ciccariello, Salvino; De Col, Alvise [Dipartimento di Fisica ' G Galilei' and Unita INFM, Padova (Italy)

    2001-11-01

    Using the zero-temperature perturbative expansion, we show how to obtain the correct value of the magnetic susceptibility of a system of free fermions at zero temperature. To this aim, it is first observed that the Feynman rules for the perturbative expansion of the Green function substantially do not change when the ground state is substituted with a generic eigenstate of the unperturbed system. Then, the requirement that the resulting Green function has the correct Lehmann representation uniquely determines the unperturbed eigenstate which yields the interacting ground state by adiabatically switching on the interaction. (author)

  15. Self-assembled magnetic bead biosensor for measuring bacterial growth and antimicrobial susceptibility testing.

    Science.gov (United States)

    Kinnunen, Paivo; McNaughton, Brandon H; Albertson, Theodore; Sinn, Irene; Mofakham, Sima; Elbez, Remy; Newton, Duane W; Hunt, Alan; Kopelman, Raoul

    2012-08-20

    Bacterial antibiotic resistance is one of the major concerns of modern healthcare worldwide, and the development of rapid, growth-based, antimicrobial susceptibility tests is key for addressing it. The cover image shows a self-assembled asynchronous magnetic bead rotation (AMBR) biosensor developed for rapid detection of bacterial growth. Using the biosensors, the minimum inhibitory concentration of a clinical E. coli isolate can be measured within two hours, where currently tests take 6-24 hours. A 16-well prototype is also constructed for simple and robust observation of the self-assembled AMBR biosensors.

  16. Magnetic susceptibility, artifact volume in MRI, and tensile properties of swaged Zr-Ag composites for biomedical applications.

    Science.gov (United States)

    Imai, Haruki; Tanaka, Yoji; Nomura, Naoyuki; Doi, Hisashi; Tsutsumi, Yusuke; Ono, Takashi; Hanawa, Takao

    2017-02-01

    Zr-Ag composites were fabricated to decrease the magnetic susceptibility by compensating for the magnetic susceptibility of their components. The Zr-Ag composites with a different Zr-Ag ratio were swaged, and their magnetic susceptibility, artifact volume, and mechanical properties were evaluated by magnetic balance, three-dimensional (3-D) artifact rendering, and a tensile test, respectively. These properties were correlated with the volume fraction of Ag using the linear rule of mixture. We successfully obtained the swaged Zr-Ag composites up to the reduction ratio of 96% for Zr-4, 16, 36, 64Ag and 86% for Zr-81Ag. However, the volume fraction of Ag after swaging tended to be lower than that before swaging, especially for Ag-rich Zr-Ag composites. The magnetic susceptibility of the composites linearly decreased with the increasing volume fraction of Ag. No artifact could be estimated with the Ag volume fraction in the range from 93.7% to 95.4% in three conditions. Young's modulus, ultimate tensile strength (UTS), and 0.2% yield strength of Zr-Ag composites showed slightly lower values compared to the estimated values using a linear rule of mixture. The decrease in magnetic susceptibility of Zr and Ag by alloying or combining would contribute to the decrease of the Ag fraction, leading to the improvement of mechanical properties.

  17. Effects of phase constitution on magnetic susceptibility and mechanical properties of Zr-rich Zr-Mo alloys.

    Science.gov (United States)

    Suyalatu; Kondo, Ryota; Tsutsumi, Yusuke; Doi, Hisashi; Nomura, Naoyuki; Hanawa, Takao

    2011-12-01

    The effects of the microstructures and phases of Zr-rich Mo alloys on their magnetic susceptibilities and mechanical properties were investigated in order to develop a Zr alloy with low magnetic susceptibility for use in magnetic resonance imaging (MRI). The magnetic susceptibility was measured with a magnetic susceptibility balance, while mechanical properties were evaluated by a tensile test. The microstructure was evaluated with an X-ray diffractometer, an optical microscope, and a transmission electron microscope. Evaluation of the microstructures revealed that the α' phase was the dominant form at less than 2% Mo content in the as-cast alloy. The ω phase was formed in as-cast Zr-3Mo but disappeared with aging at 973 K. Magnetic susceptibility was reflected in the phase constitution: the susceptibility showed a local minimum at Zr-(0.5-1)Mo with mostly α' phase and a minimum at Zr-3Mo with mostly β and ω phases. The magnetic susceptibility of as-cast Zr-3Mo increased at 973 K due to disappearance of the ω phase. However, the susceptibility was still as low as that of as-cast Zr-1Mo. The ultimate tensile strength of α'-based Zr-Mo alloys was tailored from 674 to 970 MPa, and the corresponding elongation varied from 11.1% to 2.9%. Because Zr-Mo alloys containing ω phase were found, through tensile tests, to be brittle this phase should be avoided, irrespective of the low magnetic susceptibility, in order to maintain mechanical reliability. Elongation of the Zr-3Mo alloy was dramatically improved when the phase constitution was changed to α and β phases by aging at 973 K for 86.4 ks. The magnetic susceptibilities of the α'-based Zr-Mo alloys are one-third those of Ti-6Al-4V and Ti-6Al-7Nb, and thus these Zr alloys are useful for medical devices under MRI. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  18. Inter-band effects of magnetic field on orbital susceptibility and Hall conductivity - case of bismuth

    Energy Technology Data Exchange (ETDEWEB)

    Fukuyama, H. [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan)

    2006-07-03

    Interband effects of magnetic field on orbital susceptibility and Hall conductivity have been theoretically studied with special reference to single crystal bismuth (Bi), whose energy bands near the band-edges are similar to those of Dirac electrons. It has long been known that orbital susceptibilty in Bi has a maximum when the Fermi energy is located in the band-gap and then the density of states at the Fermi energy is vanishing. This implies that the magnetic field induces persistent current even in the insulating state. On the other hand, weak-field Hall conductivity, which reflects transport current, has turned out to be vanishing if the Fermi energy is in the band-gap. Interesting possibility has been pointed out of the inter-band contributions to the Hall conductivity once the Fermi energy lies slightly in the energy band. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  19. Automated equipment for determining the magnetic susceptibility of steels and alloys

    Directory of Open Access Journals (Sweden)

    G. V. Snizhnoi

    2012-10-01

    Full Text Available Automated equipment for determining the susceptibility of steels and alloys proposed. The principle of operation of equipment units and their main characteristics are presented. Microprocessor system with AVR microcontrollers from ATMEL for equipment used. The algorithm of the program a microprocessor system for automatic operation of equipment considered. Dependence of the current compensation of the current force field as a text file on your computer equipment can be formed.

  20. Magnetic Field Dependence and Q of the Josephson Plasma Resonance

    DEFF Research Database (Denmark)

    Pedersen, Niels Falsig; Finnegan, T. F.; Langenberg, D. N.

    1972-01-01

    The results of an experimental study of the magnetic field dependence of the Josephson-plasma-resonance frequency and linewidth in Pb-Pb oxide-Pb tunnel junctions are reported. In the presence of an external magnetic field, the plasma mode is found to be sensitive to an antisymmetric component...... of supercurrent density which is not observed in conventional measurements of the field-dependent critical current. The frequency and field dependence of the plasma-resonance linewidth are interpreted as evidence that the previously unobserved quasiparticle-pair-interference tunnel current predicted by Josephson...

  1. A preliminary attempt to identify atmospherically-derived pollution particles in English topsoils from magnetic susceptibility measurements

    Science.gov (United States)

    Hay, K. L.; Dearing, J. A.; Baban, S. M. J.; Loveland, P.

    This study identifies topsoils in England having increased magnetic susceptibility (xlf) values attributable to the presence of anthropogenically produced pollution particles, such as fly-ash. The database consists of 1176 topsoils taken at 10 km intervals across the whole of England, and tested for magnetic susceptibility at low and high frequencies. Soils containing significant concentrations of pollution particles were identified using two criteria; xlf (values > 0.38 10-6m3kg-1) and xfd% (values < 3%). The ‘polluted’ topsoils are located in the south-east around London, the Midlands, the north around the conurbations of Manchester, Merseyside and West Yorkshire, and in the north-east around Newcastle and Teeside. The heavy metal concentration of the soils are elevated above background levels, and have strong positive relationships with magnetic susceptibility and other magnetic parameters.

  2. [Heavy Metals Accmultio in the Caofeidian Reclamation Soils: Indicated by Soil Magnetic Susceptibility].

    Science.gov (United States)

    Xue, Yong; Zhou, Qian; Li, Yuan; Zhang, Hai-bo; Hu, Xue-feng; Luo, Yong-ming

    2016-04-15

    The environmental magnetism method has been widely applied to identify soil heavy metal pollution, which is characterized by simplicity, efficiency, non-destructivity and sensitivity. The present study used magnetic susceptibility to assess the accumulation of heavy metals in soils of the Caofeidian industrial zone which is a typical reclamation area in northern China. The study area was divided into three sub-zones based on the function, including industrial zone, living zone, natural tidal flat and wetland. A total of 35 topsoil samples (0-10 cm) and 3 soil profiles were collected from the three sub-zones. Magnetic susceptibility (X(lf)), iron oxide (Fe2O3) contents and heavy metals contents (Cr, Ni, Cu, Zn, As, Pb, Mn and V) of the samples were analyzed. The results showed that X(lf) values and heavy metals contents exhibited higher spatial variability in the top soil of the industrial zone, indicating the severe impacts of industrial activities. In the soil profiles of the industrial and living zones, all heavy metals were enriched to different degrees in the upper layer (0-20 cm). However, there was no significant change of heavy metal contents in the soil profiles of tidal flat which was far from the industrial area. The X(lf) value was significantly (P soil. This indicated that X(lf) could be used as an indicator for heavy metal accumulation in the industrial zone. However, the X(lf) value was not suitable to be an indicator to show the heavy metal accumulation in the soils of living zone and natural tidal flat. This might be associated with the different sources of magnetic materials among the different sub-zones and the special characteristics of the soils in the tidal flat and wetland.

  3. RECONSTRUCTING PALEO-SMT POSITIONS ON THE CASCADIA MARGIN USING MAGNETIC SUSCEPTIBILITY

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Joel [Univ. of New Hampshire, Durham, NH (United States); Phillips, Stephen [Univ. of New Hampshire, Durham, NH (United States)

    2014-09-30

    Magnetic susceptibility (κ) is a mixed signal in marine sediments, representing primary depositional and secondary diagenetic processes. Production of hydrogen sulfide via anaerobic oxidation of methane (AOM) at the sulfate-methane transition (SMT) and organoclastic sulfate reduction above the SMT can result in the dissolution of iron oxides, altering κ in sediments in methane gas and gas hydrate bearing regions. We investigated records of κ on the Cascadia margin (ODP Sites 1249 and 1252; IODP Site 1325) using a Zr/Rb heavy mineral proxy from XRF core scanning to identify intervals of primary detrital magnetic susceptibility and intervals and predict intervals affected by magnetite dissolutions. We also measured total sulfur content, grain size distributions, total organic carbon (TOC) content, and magnetic mineral assemblage. The upper 100 m of Site 1252 contains a short interval of κ driven by primary magnetite, with multiple intervals (> 90 m total) of decreased κ correlated with elevated sulfur content, consistent with dissolution of magnetite and re-precipitation of pyrite. In the upper 90 m of Site 1249, κ is almost entirely altered by diagenetic processes, with much of the low κ explained by a high degree of pyritization, and some intervals affected by the precipitation of magnetic iron sulfides. At Site 1325, κ between 0-20 and 51-73 mbsf represents primary mineralogy, and in the interval 24-51 mbsf, κ may be reduced due to pyritization. This integrated approach allows for a prediction of primary κ and the amount of κ loss at each site when compared to actual κ measurements. In the case of magnetite dissolution and full pyritization, these drawdowns in κ are supported by sulfur measurements, and the exposure times of magnetite to hydrogen sulfide can be modeled. The presence of methane and methane hydrates at these sites, as well as large variations in TOC content, suggest that the past migration rates of the SMT and variation in sulfate

  4. Age-dependent susceptibility to phenobarbital-resistant neonatal seizures: role of chloride co-transporters

    Directory of Open Access Journals (Sweden)

    Seok Kyu eKang

    2015-05-01

    Full Text Available Ischemia in the immature brain is an important cause of neonatal seizures. Temporal evolution of acquired neonatal seizures and their response to anticonvulsants are of great interest, given the unreliability of the clinical correlates and poor efficacy of first-line anti-seizure drugs. The expression and function of the electroneutral chloride co-transporters KCC2 and NKCC1 influence the anti-seizure efficacy of GABAA-agonists. To investigate ischemia-induced seizure susceptibility and efficacy of the GABAA-agonist phenobarbital (PB, with NKCC1 antagonist bumetanide (BTN as an adjunct treatment, we utilized permanent unilateral carotid-ligation to produce acute ischemic-seizures in postnatal day 7, 10 and 12 CD1 mice. Immediate post-ligation video-electroencephalograms (EEGs quantitatively evaluated baseline and post-treatment seizure burdens. Brains were examined for stroke-injury and western blot analyses to evaluate the expression of KCC2 and NKCC1. Severity of acute ischemic seizures post-ligation was highest at P7. PB was an efficacious anti-seizure agent at P10 and P12, but not at P7. BTN failed as an adjunct, at all ages tested and significantly blunted PB-efficacy at P10. Significant acute post-ischemic downregulation of KCC2 was detected at all ages. At P7, males displayed higher age-dependent seizure susceptibility, associated with a significant developmental lag in their KCC2 expression. This study established a novel neonatal mouse model of PB-resistant seizures that demonstrates age/sex-dependent susceptibility. The age-dependent profile of KCC2 expression and its post-insult downregulation may underlie the PB-resistance reported in this model. Blocking NKCC1 with low-dose BTN following PB treatment failed to improve PB-efficacy.

  5. Vortex dynamics and irreversibility line in optimally doped SmFeAsO0.8F0.2 from ac susceptibility and magnetization measurements

    Science.gov (United States)

    Prando, G.; Carretta, P.; de Renzi, R.; Sanna, S.; Palenzona, A.; Putti, M.; Tropeano, M.

    2011-05-01

    Ac susceptibility and static magnetization measurements were performed in the optimally doped SmFeAsO0.8F0.2 superconductor. The field-temperature phase diagram of the superconducting state was drawn, and, in particular, the features of the flux lines were derived. The dependence of the intragrain depinning energy on the magnetic field intensity was derived in the thermally activated flux-creep framework, enlightening a typical 1/H dependence in the high-field regime. The intragrain critical current density was extrapolated in the zero-temperature and zero-magnetic-field limit, showing a remarkably high value Jc0(0)~2×107 A/cm2, which demonstrates that this material is rather interesting for potential future technological applications.

  6. $N_f=1+2$ mass dependence of the topological susceptibility

    CERN Document Server

    Frison, Julien; Yamada, Norikazu

    2016-01-01

    A massless up quark has long been proposed as a solution to the strong CP problem. While this solution is sometimes thought to have been excluded, it is actually still ill-defined. In this work, we study the mass dependence of the physical observable $\\chi_t$, the topological susceptibility. Assigning an unphysically large value to the down mass allows to be more sensitive to the non-perturbative effects behind the $m_u=0$ ambiguity. Preliminary results are presented for four masses of clover fermions.

  7. Magnetic susceptibility and element composition mangrove sediments in Malang, East Java

    Science.gov (United States)

    Azzahro, Rosyida; Zulaikah, Siti; Diantoro, Markus; Budi, Pranitha Septiana

    2017-07-01

    Mangrove sediment has a unique environmental absorption characteristics, as it has two sources of sediment which are from allocthonous sediment and authochtonous sediment. In this research, the mangrove sediment samples are taken from Clungup Mangrove Conservation in Malang, East Java, Indonesia. The samples are taken from four spots around the mouth of the river, and four spots around mangrove conservation. Those samples are analyzed based on the magnetic characteristics and the element composition to reveal the magnetic properties and element composition so in the future they can be used as indicators to trace the source of magnetic minerals that are precipitated in the mangrove ecosystem. The magnetic susceptibility value based on mass for mangrove sediment around the river area h as the range of (38,8-2130)×10-8m3kg-1, while for the conservation area has the range of (0,97-122,5)×10-8m3kg-1. Based on XRF analysis, the mangrove sediment both from the river area and mangrove conservation area has a non-metallic element S, Br, metallic element Ca, Si, Al, K, Ti, Sr, and heavy metallic element Fe, Ni, Cu, Cr, Zn, Zr, Mn, and V, with the highest concentration of Fe element followed by Ca, Al, Si, and Ti.

  8. Thermomagnetic behavior of magnetic susceptibility – heating rate and sample size effects

    Directory of Open Access Journals (Sweden)

    Diana eJordanova

    2016-01-01

    Full Text Available Thermomagnetic analysis of magnetic susceptibility k(T was carried out for a number of natural powder materials from soils, baked clay and anthropogenic dust samples using fast (11oC/min and slow (6.5oC/min heating rates available in the furnace of Kappabridge KLY2 (Agico. Based on the additional data for mineralogy, grain size and magnetic properties of the studied samples, behaviour of k(T cycles and the observed differences in the curves for fast and slow heating rate are interpreted in terms of mineralogical transformations and Curie temperatures (Tc. The effect of different sample size is also explored, using large volume and small volume of powder material. It is found that soil samples show enhanced information on mineralogical transformations and appearance of new strongly magnetic phases when using fast heating rate and large sample size. This approach moves the transformation at higher temperature, but enhances the amplitude of the signal of newly created phase. Large sample size gives prevalence of the local micro- environment, created by evolving gases, released during transformations. The example from archeological brick reveals the effect of different sample sizes on the observed Curie temperatures on heating and cooling curves, when the magnetic carrier is substituted magnetite (Mn0.2Fe2.70O4. Large sample size leads to bigger differences in Tcs on heating and cooling, while small sample size results in similar Tcs for both heating rates.

  9. Geophysical monitoring of simulated graves with resistivity, magnetic susceptibility, conductivity and GPR in Colombia, South America.

    Science.gov (United States)

    Molina, Carlos Martin; Pringle, Jamie K; Saumett, Miguel; Evans, Gethin T

    2016-04-01

    In most Latin American countries there are significant numbers of both missing people and forced disappearances, ∼71,000 Colombia alone. Successful detection of buried human remains by forensic search teams can be difficult in varying terrain and climates. Three clandestine burials were simulated at two different depths commonly encountered in Latin America. In order to gain critical knowledge of optimum geophysical detection techniques, burials were monitored using: ground penetrating radar, magnetic susceptibility, bulk ground conductivity and electrical resistivity up to twenty-two months post-burial. Radar survey results showed good detection of modern 1/2 clothed pig cadavers throughout the survey period on 2D profiles, with the 250MHz antennae judged optimal. Both skeletonised and decapitated and burnt human remains were poorly imaged on 2D profiles with loss in signal continuity observed throughout the survey period. Horizontal radar time slices showed good anomalies observed over targets, but these decreased in amplitude over the post-burial time. These were judged due to detecting disturbed grave soil rather than just the buried targets. Magnetic susceptibility and electrical resistivity were successful at target detection in contrast to bulk ground conductivity surveys which were unsuccessful. Deeper burials were all harder to image than shallower ones. Forensic geophysical surveys should be undertaken at suspected burial sites.

  10. Magnetic susceptibility variations of carbonates controlled by sea-level changes——Examples in Devonian to Carboniferous strata in southern Guizhou Province,China

    Institute of Scientific and Technical Information of China (English)

    张世红; 王训练; 朱鸿

    2000-01-01

    This paper presents magnetic susceptibility results of 578 samples from three De-vono-Carboniferous carbonate successions in the Yangtze Block. They indicate that the magnetic susceptibility variations in carbonates are controlled by ancient sea-level changes. It is particularly so if the supply of detrital materials was low, when the magnetic susceptibility was mainly controlled by the content of authigenic minerals. If the supply of detrital materials was high, the average susceptibility value would be higher, but there is still a correlation between susceptibility and sea-level curves. A sea level rise would lead to a decrease in the content of the detrital materials, and therefore to a decrease in the susceptibility values. On the top of HST, the uplift and exposure events may lead to elevated magnetic susceptibility values. Carbonate susceptibilities can therefore be considered as one of the environmental proxy data for the research of sequence stratigraphy.

  11. Magnetic susceptibility variations of carbonates controlled by sea-level changes--Examples in Devonian to Carboniferous strata in southern Guizhou Province, China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper presents magnetic susceptibility results of 578 samples from three Devono-Carboniferous carbonate successions in the Yangtze Block. They indicate that the magnetic susceptibility variations in carbonates are controlled by ancient sea-level changes. It is particularly so if the supply of detrital materials was low, when the magnetic susceptibility was mainly controlled by the content of authigenic minerals. If the supply of detrital materials was high, the average susceptibility value would be higher, but there is still a correlation between susceptibility and sea-level curves. A sea level rise would lead to a decrease in the content of the detrital materials, and therefore to a decrease in the susceptibility values. On the top of HST, the uplift and exposure events may lead to elevated magnetic susceptibility values. Carbonate susceptibilities can therefore be considered as one of the environmental proxy data for the research of sequence stratigraphy.

  12. Angular-dependent magnetization reversal processes in artificial spin ice

    Science.gov (United States)

    Burn, D. M.; Chadha, M.; Branford, W. R.

    2015-12-01

    The angular dependence of the magnetization reversal in interconnected kagome artificial spin ice structures has been studied through experimental MOKE measurements and micromagnetic simulations. This reversal is mediated by the propagation of magnetic domain walls along the interconnecting bars, which either nucleate at the vertex or arrive following an interaction in a neighboring vertex. The physical differences in these processes show a distinct angular dependence allowing the different contributions to be identified. The configuration of the initial magnetization state, either locally or on a full sublattice of the system, controls the reversal characteristics of the array within a certain field window. This shows how the available magnetization reversal routes can be manipulated and the system can be trained.

  13. Molecular engineering of lanthanide ion chelating phospholipids generating assemblies with a switched magnetic susceptibility.

    Science.gov (United States)

    Isabettini, Stéphane; Massabni, Sarah; Hodzic, Arnel; Durovic, Dzana; Kohlbrecher, Joachim; Ishikawa, Takashi; Fischer, Peter; Windhab, Erich J; Walde, Peter; Kuster, Simon

    2017-08-09

    Lanthanide ion (Ln(3+)) chelating amphiphiles are powerful molecules for tailoring the magnetic response of polymolecular assemblies. Mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dimyristoyl-sn-glycero-3-phospho-ethanolamine-diethylene triaminepentaacetate (DMPE-DTPA) complexed to Ln(3+) deliver highly magnetically responsive bicelles. Their magnetic properties are readily tuned by changing the bicellar size or the magnetic susceptibility Δχ of the bilayer lipids. The former technique is intrinsically bound to the region of the phase diagram guarantying the formation of bicelles. Methods aiming towards manipulating the Δχ of the bilayer are comparatively more robust, flexible and lacking. Herein, we synthesized a new Ln(3+) chelating phospholipid using glutamic acid as a backbone: DMPE-Glu-DTPA. The chelate polyhedron was specifically engineered to alter the Δχ, whilst remaining geometrically similar to DMPE-DTPA. Planar asymmetric assemblies hundreds of nanometers in size were achieved presenting unprecedented magnetic alignments. The DMPE-Glu-DTPA/Ln(3+) complex switched the Δχ, achieving perpendicular alignment of assemblies containing Dy(3+) and parallel alignment of those containing Tm(3+). Moreover, samples with chelated Yb(3+) were more alignable than the Tm(3+) chelating counterparts. Such a possibility has never been demonstrated for planar Ln(3+) chelating polymolecular assemblies. The physico-chemical properties of these novel assemblies were further studied by monitoring the alignment behavior at different temperatures and by including 16 mol% of cholesterol (Chol-OH) in the phospholipid bilayer. The DMPE-Glu-DTPA/Ln(3+) complex and the resulting assemblies are promising candidates for applications in numerous fields including pharmaceutical technologies, structural characterization of membrane biomolecules by NMR spectroscopy, as contrasting agents for magnetic resonance imaging, and for the development of smart

  14. Field orientation dependence of magnetization reversal in thin films with perpendicular magnetic anisotropy

    Science.gov (United States)

    Fallarino, Lorenzo; Hovorka, Ondrej; Berger, Andreas

    2016-08-01

    The magnetization reversal process of hexagonal-close-packed (hcp) (0001) oriented Co and C o90R u10 thin films with perpendicular magnetic anisotropy (PMA) has been studied as a function of temperature and applied magnetic field angle. Room temperature pure cobalt exhibits two characteristic reversal mechanisms. For angles near in-plane field orientation, the magnetization reversal proceeds via instability of the uniform magnetic state, whereas in the vicinity of the out-of-plane (OP) orientation, magnetization inversion takes place by means of domain nucleation. Temperature dependent measurements enable the modification of the magnetocrystalline anisotropy and reveal a gradual disappearance of the domain nucleation process during magnetization reversal for elevated temperatures. Ultimately, this suppression of the domain nucleation process leads to the exclusive occurrence of uniform state instability reversal for all field orientations at sufficiently high temperature. Comparative magnetic measurements of C o90R u10 alloy samples allow the identification and confirmation of the high temperature remanent magnetization state of cobalt as an OP stripe domain state despite the reduction of magnetocrystalline anisotropy. Detailed micromagnetic simulations supplement the experimental results and corroborate the physical understanding of the temperature dependent behavior. Moreover, they enable a comprehensive identification of the complex energy balance in magnetic films with PMA, for which three different magnetic phases occur for sufficiently high anisotropy values, whose coexistence point is tricritical in nature.

  15. Uncertainty of spatial distributions of soil magnetic susceptibility in areas of different type of land cover and anthropogenic pressure

    Science.gov (United States)

    Zawadzki, Jaroslaw; Fabijańczyk, Piotr

    2016-04-01

    There is still a high interest in the improvement of soil magnetometry procedures that would increase its accuracy. Soil magnetometry is usually used as a fast screening method that is used to assess the degree of soil pollution. As the magnetometric measurements do not provide the exact information about the concentration of elements in soil, it is very important to determine the uncertainty of the spatial distributions of soil magnetic susceptibility. The goal of this study was to analyze and present geostatistical methods of assessing the uncertainty of spatial distribution of soil magnetic susceptibility in areas of different land cover and anthropogenic pressure. In particular, spatial distributions of magnetic susceptibility measured on the soil surface using a MS2D Bartington device were calculated using indicator methods that make it possible to calculate the probability of exceeding the critical levels of soil magnetic susceptibility. Measurements were performed in areas located in the Upper Silesian Industrial Area in Poland, and in Norway. In these areas soil magnetic susceptibility was measured on the soil surface using a MS2D Bartington device. Additionally, soil samples were taken in order to perform chemical measurements that included the determination of a concentration of selected elements. Acknowledgment The research leading to these results has received funding from the Polish-Norwegian Research Programme operated by the National Centre for Research and Development underthe Norwegian Financial Mechanism 2009-2014 in the frame of Project IMPACT - Contract No Pol-Nor/199338/45/2013.

  16. Anisotropy of magnetic susceptibility (AMS) in the Siilinjärvi carbonatite complex, eastern Finland

    Science.gov (United States)

    Almqvist, Bjarne; Karell, Fredrik; Högdahl, Karin; Malehmir, Alireza; Heino, Pasi; Salo, Aleksi

    2017-04-01

    We present a set of AMS measurements on samples from the Siilinjärvi alkaline-carbonatite complex in eastern Finland. The complex has a tabular shape (ca. 16 km long, 1.5 km wide) that strikes north-south and is constrained within a steeply dipping N-S oriented deformation zone. It consists of a mixture of lithologies, including carbonatite, fenite and glimmerite (mica-rich rocks), which is hosted within a Precambrian granite and gneiss. After emplacement of the carbonatite, the complex was subsequently intruded by diabase dykes. Deformation has occurred in several episodes after dyke intrusions, and strain is heterogeneously distributed among the different lithologies. Strain localizes mainly within glimmerite and carbonatite, and at the contacts between dykes and glimmerite/carbonatite where shear zones develop locally. Structures provide indications for both simple (strike-slip) and pure shear components in the deformation history of the complex, although the former may dominate. Thirty-six localities were sampled, providing 272 specimens for AMS measurements, within the southern and eastern parts of the Siilinjärvi open-pit mine (within the complex), mainly from diabase dykes, glimmerite and carbonatites; a smaller number of samples were collected from fenite. Sampling was carried out in order to investigate magnetic fabrics in relation to the emplacement of the dykes and their structural relationship to the glimmerite/carbonatite. Structural measurements were made to accompany the magnetic fabric study. The magnetic fabric shows a magnetic foliation plane that is oriented north-south, with sub-horizontal k3-axes oriented nearly east-west. Magnetic lineation (k1) clusters sub-vertically, but does show a tendency to spread along the north-south magnetic foliation great circle. The dataset can be further divided into two sub-sets based on the bulk susceptibility (km) and degree of anisotropy (P). The bulk of the data set ( 70 %), belonging to samples of diabase

  17. Enhancement of Second- and Third-Order Nonlinear Optical Susceptibilities in Magnetized Semiconductors

    Institute of Scientific and Technical Information of China (English)

    M. Singh; P. Aghamkar; S. Duhan

    2008-01-01

    Using electromagnetic treatment, an expression of effective nonlinear optical susceptibility Xe[= Xe(2) + Xe(3) E] is obtained for Ⅲ-Ⅴ semiconducting crystals in an applied transverse dc magnetic field under off-resonant transition regime. The origin of nonlinear interaction lies in nonlinear polarization arising from the crystal properties such as piezoelectricity and electrostriction. Numerical estimates have been made by a representative n-InSb crystal at 77K duly irradiated by a pulsed lO.6-μm CO2 laser under off-resonant transition regime. Efforts are dedicated to optimizing doping level and externally applied dc magnetic field to achieve maximum Xe(2) and Xe(3). The results are found to be in good agreement with the available literature. The analysis shows that Xe(2) and Xe(3)can be significantly enhanced in doped Ⅲ-Ⅴ semiconductors by the proper selection of doping concentration and dc magnetic field, which confirms its potential as a candidate material for the fabrication of nonlinear optical devices.

  18. Magnetic susceptibility and hardness of Au-xPt-yNb alloys for biomedical applications.

    Science.gov (United States)

    Uyama, Emi; Inui, Shihoko; Hamada, Kenichi; Honda, Eiichi; Asaoka, Kenzo

    2013-09-01

    Metal devices in the human body induce serious metal artifacts in magnetic resonance imaging (MRI). Metals artifacts are mainly caused by a volume magnetic susceptibility (χv) mismatch between a metal device and human tissue. In this research, Au-xPt-yNb alloys were developed for fabricating MRI artifact-free biomedical metal devices. The magnetic properties, hardness and phase constitutions of these alloys were investigated. The Au-xPt-8Nb alloys showed satisfactory χv values. Heat treatments did not clearly change the χv values for Au-xPt-8Nb alloys. The Vickers hardness (HV) of these two alloys was much higher than that of high-Pt alloys; moreover, aging at 700°C increased the HV values of these two alloys. A dual phase structure consisting of face-centered cubic α1 and α2 phases was observed and aging at 700°C promoted phase separation. The Au-5Pt-8Nb and Au-10Pt-8Nb alloys showed satisfactory χv values and high hardness and are thus suggested as candidates for MRI artifact-free alloys for biomedical applications.

  19. Carrier-dependent magnetic anisotropy of Gd-adsorbed graphene

    Science.gov (United States)

    Lu, Yuan; Zhou, Tie-ge; Shao, Bin; Zuo, Xu; Feng, Min

    2016-05-01

    Using first-principles calculation based on density functional theory, we study the magnetic anisotropy of Gd-adsorbed graphene and its dependence on carrier accumulation. We show that carrier accumulation not only impacts the magnitude of magnetic anisotropy but also switches its sign. Hole accumulation enhances the perpendicular anisotropy up to ˜16 meV per Gd atom, while electron accumulation switches the anisotropy from perpendicular to in-plane direction. Moreover, we find that the first order perturbation of spin-orbit coupling interaction induces a pseudo-gap at Γ for the perpendicular magnetization, which leads to the the anomalous magnetic anisotropy for the neutral composite. Our findings pave the way for magneto-electric materials based on rare-earth-decorated graphene for voltage-controlled spintronics.

  20. Carrier-dependent magnetic anisotropy of Gd-adsorbed graphene

    Directory of Open Access Journals (Sweden)

    Yuan Lu

    2016-05-01

    Full Text Available Using first-principles calculation based on density functional theory, we study the magnetic anisotropy of Gd-adsorbed graphene and its dependence on carrier accumulation. We show that carrier accumulation not only impacts the magnitude of magnetic anisotropy but also switches its sign. Hole accumulation enhances the perpendicular anisotropy up to ∼16 meV per Gd atom, while electron accumulation switches the anisotropy from perpendicular to in-plane direction. Moreover, we find that the first order perturbation of spin-orbit coupling interaction induces a pseudo-gap at Γ for the perpendicular magnetization, which leads to the the anomalous magnetic anisotropy for the neutral composite. Our findings pave the way for magneto-electric materials based on rare-earth-decorated graphene for voltage-controlled spintronics.

  1. Gate-dependent orbital magnetic moments in carbon nanotubes

    DEFF Research Database (Denmark)

    Jespersen, Thomas Sand; Grove-Rasmussen, Kasper; Flensberg, Karsten;

    2011-01-01

    We investigate how the orbital magnetic moments of electron and hole states in a carbon nanotube quantum dot depend on the number of carriers on the dot. Low temperature transport measurements are carried out in a setup where the device can be rotated in an applied magnetic field, thus enabling...... accurate alignment with the nanotube axis. The field dependence of the level structure is measured by excited state spectroscopy and excellent correspondence with a single-particle calculation is found. In agreement with band structure calculations we find a decrease of the orbital magnetic moment...... with increasing electron or hole occupation of the dot, with a scale given by the band gap of the nanotube....

  2. Temperature dependence of magnetocurrent in a magnetic tunnel transistor

    NARCIS (Netherlands)

    Park, B.G.; Banerjee, T.; Min, B.C.; Sanderink, J.G.M.; Lodder, J.C.; Jansen, R.

    2005-01-01

    The temperature dependence of magnetocurrent (MC) and transfer ratio has been investigated in a magnetic tunnel transistor (MTT) with a ferromagnetic (FM) emitter of Co or Ni80Fe20. MTT devices of sizes ranging from 10 to 100 µm in diameter were fabricated using a standard photolithography process a

  3. Ferromagnetic resonance, transverse bias initial inverse susceptibility and torque studies of magnetic properties of Co2MnSi thin films

    Directory of Open Access Journals (Sweden)

    Devolder T.

    2013-01-01

    Full Text Available Magnetic properties of Co2MnSi thin films of 20 nm and 50 nm in thickness grown by radio frequency sputtering on a-plane sapphire substrates have been studied. X-ray diffraction (XRD revealed that the cubic Co2MnSi axis is normal to the substrate and that well defined preferential in-plane orientations are present. The static magnetic properties were studied at room temperature by conventional magneto-optical Kerr effect (MOKE, transverse bias initial inverse susceptibility and torque (TBIIST MOKE. The dynamic magnetic properties were investigated by micro-strip ferromagnetic resonance (MS-FMR at room temperature. The resonance and TBIIST measurements versus the direction of the in-plane applied magnetic field reveal that the in-plane anisotropy results from the superposition of a two-fold and a four-fold symmetry. The directions of the principal axes of the twofold anisotropy are sample dependent. The angular dependence of remanent normalized magnetizations and coercive fields, studied by MOKE are analyzed within the frame of a coherent rotation model. A good agreement is observed between the field anisotropy values obtained from MSFMR and from TBIIST data. Frequency and angular dependence of FMR linewidth has been studied. Apparent damping coefficient of 0.0112 has been measured for 50 nm thick sample.

  4. Magnetic susceptibility at zero and nonzero chemical potential in QCD and QED

    Science.gov (United States)

    Orlovsky, V. D.; Simonov, Yu. A.

    2015-04-01

    Magnetic susceptibility of the quark and electron gas is calculated in a closed form for any chemical potential μ summing the whole Matsubara series. For the quark gas and small μ≪T a strong rise with T is found due to Polyakov loop factors L(T), in good agreement with lattice data. For the electron gas the lowest Matsubara term (n = 1) contributes 40% larger than the exact answer. In the case of small T, √ {eB} ≳ T, the oscillations as functions of eB occur, characteristic of the de Haas-van Alphen effect. Results are compared with available lattice data and with the case of relativistic electron gas, which obtains putting L(T)≡1.

  5. Fahr disease: use of susceptibility-weighted imaging for diagnostic dilemma with magnetic resonance imaging.

    Science.gov (United States)

    Sahin, Neslin; Solak, Aynur; Genc, Berhan; Kulu, Ugur

    2015-08-01

    Fahr disease (FD) is a well-defined rare neurodegenerative disease that is characterized by idiopathic bilateral symmetric extensive striopallidodentate calcifications. The patients may present with diverse manifestations, most commonly movement disorder, cognitive impairment, and ataxia. Computed tomography (CT) is considered to be critical for accurate diagnosis because it is difficult to reliably identify calcifications by routine magnetic resonance imaging (MRI). Susceptibility-weighted imaging (SWI) is a relatively new 3D gradient-echo (GE) MR sequence with special phase and magnitude processing. SWI phase images can recognize calcifications definitively with higher sensitivity compared to other MRI sequences. In this article, we present two cases of FD with different manifestations and neuroimaging in different age groups and genders, which were diagnosed by SWI and confirmed with CT, and we discuss the contribution of SWI in the diagnosis of FD. In conclusion, we suggest integrating SWI with MRI protocol to identify calcifications in suspicion of neurodegenerative disorders.

  6. Magnetic susceptibility data for some exposed bedrock in the western conterminous United States

    Science.gov (United States)

    Gettings, Mark E.; Bultman, Mark W.

    2014-01-01

    In-place rock magnetic susceptibility measurements for 746 sites in the western conterminous United States are reported in a database. Of these 746 sites, 408 sites are in the Silverton Caldera area of the San Juan Mountains of southwestern Colorado. Of the 408 sites in the Silverton Caldera area, 106 sites are underground. The remaining 338 sites outside the Silverton Caldera area were on outcropping rock, are distributed from southern Arizona to northwestern Wyoming, and include data from California, Nevada, Utah, Colorado, and New Mexico. Rock-density measurements are included for some sites. These data have been collected by various U.S. Geological Survey studies from 1991 through 2012 and are intended to help improve geophysical modeling of the Earth’s crust in the Western United States. A map-based graphical user interface is included to facilitate use of the data.

  7. Dynamic susceptibility contrast magnetic resonance imaging in neuropsychiatry: present utility and future promise

    Energy Technology Data Exchange (ETDEWEB)

    Renshaw, P.F.; Levin, J.M.; Kaufman, M.J.; Ross, M.H. [Brain Imaging Center, McLean Hospital, 115 Mill Street, Belmont, MA 02178 (United States); Lewis, R.F.; Harris, G.J. [Neuroimaging Research Laboratory, New England Medical Center, Boston, Massachusetts (United States)

    1997-12-31

    Dynamic susceptibility contrast magnetic resonance imaging (DSC MRI) provides a noninvasive means to create high resolution maps of the regional distribution of cerebral blood volume (CBV). Most DSC MRI studies conducted to date have focused on the evaluation of patients with cerebral neoplasms, ischemia or infarction, and epilepsy. However, preliminary work suggests that DSC MRI may also provide clinically important information for the evaluation of patients with neuropsychiatric disorders, especially dementia and schizophrenia. Additionally, with appropriate modification, DSC MRI may be used to reliably evaluate the effects of pharmacological challenges on cerebral hemodynamics. As pharmacotherapy is an important component in the treatment of a range of psychiatric disorders, the dynamic assessment of changes in cerebral perfusion associated with drug administration may ultimately lead to the development of ``brain function tests`` for a wide range of disorders. (orig.) With 4 figs., 50 refs.

  8. Magnetic susceptibility and heat capacity of graphene in two-band Harrison model

    Science.gov (United States)

    Mousavi, Hamze; Bagheri, Mehran; Khodadadi, Jabbar

    2015-11-01

    Using a two-band tight-binding Harrison model and Green's function technique, the influences of both localized σ and delocalized π electrons on the density of states, the Pauli paramagnetic susceptibility, and the heat capacity of a graphene sheet are investigated. We witness an extension in the bandwidth and an increase in the number of Van-Hove singularities as well. As a notable point, besides the magnetic nature which includes diamagnetism in graphene-based nanosystems, a paramagnetic behavior associated with the itinerant π electrons could be occurred. Further, we report a Schottky anomaly in the heat capacity. This study asserts that the contribution of both σ and π electrons play dominant roles in the mentioned physical quantities.

  9. Magnetic susceptibility as a proxy for investigating microbially mediated iron reduction

    Science.gov (United States)

    Mewafy, Farag M.; Atekwana, Estella A.; Werkema, D. Dale, Jr.; Slater, Lee D.; Ntarlagiannis, Dimitrios; Revil, André; Skold, Magnus; Delin, Geoffrey N.

    2011-11-01

    We investigated magnetic susceptibility (MS) variations in hydrocarbon contaminated sediments. Our objective was to determine if MS can be used as an intrinsic bioremediation indicator due to the activity of iron-reducing bacteria. A contaminated and an uncontaminated core were retrieved from a site contaminated with crude oil near Bemidji, Minnesota and subsampled for MS measurements. The contaminated core revealed enriched MS zones within the hydrocarbon smear zone, which is related to iron-reduction coupled to oxidation of hydrocarbon compounds and the vadose zone, which is coincident with a zone of methane depletion suggesting aerobic or anaerobic oxidation of methane is coupled to iron-reduction. The latter has significant implications for methane cycling. We conclude that MS can serve as a proxy for intrinsic bioremediation due to the activity of iron-reducing bacteria iron-reducing bacteria and for the application of geophysics to iron cycling studies.

  10. Susceptibility weighted imaging: a new tool in magnetic resonance imaging of stroke

    Energy Technology Data Exchange (ETDEWEB)

    Santhosh, K. [Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum (India); Kesavadas, C. [Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum (India)], E-mail: chandkesav@yahoo.com; Thomas, B.; Gupta, A.K.; Thamburaj, K.; Kapilamoorthy, T. Raman [Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum (India)

    2009-01-15

    Susceptibility weighted imaging (SWI) is a magnetic resonance (MR) technique that is exquisitely sensitive to paramagnetic substances, such as deoxygenated blood, blood products, iron, and calcium. This sequence allows detection of haemorrhage as early as 6 h and can reliably detect acute intracerebral parenchymal, as well as subarachnoid haemorrhage. It detects early haemorrhagic transformation within an infarct and provides insight into the cerebral haemodynamics following stroke. It helps in the diagnosis of cerebral venous thrombosis. It also has applications in the work-up of stroke patients. The sequence helps in detecting microbleeds in various conditions, such as vasculitis, cerebral autosomal dominant arteriopathy, subacute infarcts and leucoencephalopathy (CADASIL), amyloid angiopathy, and Binswanger's disease. The sequence also aids in the diagnosis of vascular malformations and perinatal cerebrovascular injuries. This review briefly illustrates the utility of this MR technique in various aspects of stroke diagnosis and management.

  11. Effect of Low-Frequency AC Magnetic Susceptibility and Magnetic Properties of CoFeB/MgO/CoFeB Magnetic Tunnel Junctions

    Directory of Open Access Journals (Sweden)

    Yuan-Tsung Chen

    2014-01-01

    Full Text Available In this investigation, the low-frequency alternate-current (AC magnetic susceptibility (χac and hysteresis loop of various MgO thickness in CoFeB/MgO/CoFeB magnetic tunneling junction (MTJ determined coercivity (Hc and magnetization (Ms and correlated that with χac maxima. The multilayer films were sputtered onto glass substrates and the thickness of intermediate barrier MgO layer was varied from 6 to 15 Å. An experiment was also performed to examine the variation of the highest χac and maximum phase angle (θmax at the optimal resonance frequency (fres, at which the spin sensitivity is maximal. The results reveal that χac falls as the frequency increases due to the relationship between magnetization and thickness of the barrier layer. The maximum χac is at 10 Hz that is related to the maximal spin sensitivity and that this corresponds to a MgO layer of 11 Å. This result also suggests that the spin sensitivity is related to both highest χac and maximum phase angle. The corresponding maximum of χac is related to high exchange coupling. High coercivity and saturation magnetization contribute to high exchange-coupling χac strength.

  12. Distribution characteristics of magnetic susceptibility of the surface sediments in the southern Yellow Sea

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The characteristic distributions of magnetic susceptibility (MS) are analyzed on the basis of susceptibility of 172 surface sediment samples in the southern Yellow Sea (SYS). The preliminary results are as follows: first, the distributions clearly correspond to different modern sediment assemblages in the continental sea, which indicates different sediment origins. With the 30 μCGS isoline being taken as demarcation line, the study area can then be divided into section H (high MS value area) and section L (low MS value area). Section H is mainly adjacent to land with two main sources of the Changjiang River and the Huanghe River.Section L is mainly an eddy sediment area, where Yellow Sea Cold Water is entrenched all the year round. The distribution pattern of MS could tell apart strong or weak hydrodynamic conditions and has a close relation to the circulation system in this area. At the areas of the SYS Circumfluent and northern East China Sea (NECS) Circumfluent (weak hydrodynamic), the MS has low values, while in the areas of Coastal Current (strong hydrodynamic), the values are high. At the same time, the oxidizing areas tend to take on higher MS, while the reducing areas have lower one. It seems safe to say that the MS in the continental sea reflects more of the sediment origin and sedimentary environment, which is different from that of loess, lake and surface soil as a climate proxy.

  13. Distribution characteristics of magnetic susceptibility of the surface sediments in the southern Yellow Sea

    Institute of Scientific and Technical Information of China (English)

    GEShulan; SHIXuefa; HANYibing

    2003-01-01

    The characteristic distributions of magnetic susceptibility (MS) are analyzed on the basis of susceptibility of 172 surface sediment samples in the southern Yellow Sea (SYS). The preliminary results are as follows: first, the distributions clearly correspond to different modern sediment assemblages in the continental sea, which indicates different sediment origins. With the 30 μCGS isoline being taken as demarcation line, the study area can then be divided into section H (high MS value area) and section L (low MS value area). Section H is mainly adjacent to land with two main sources of the Changjiang River and the Huanghe River.Section L is mainly an eddy sediment area, where Yellow Sea Cold Water is entrenched all the year round. The distribution pattern of MS could tell apart strong or weak hydrodynamic conditions and has a close relation to the circulation system in this area. At the areas of the SYS Circumfluent and northern East China Sea (NECS) Circumfluent (weak hydrodynamic), the MS has low values, while in the areas of Coastal Current (strong hydrodynamic), the values are high.At the same time, the oxidizing areas tend to take on higher MS, while the reducing areas have lower one. It seems safe to say that the MS in the continental sea reflects more of the sediment origin and sedimentary environment, which is different from that of loess, lake and surface soil as a climate proxy.

  14. Design and development of novel MRI compatible zirconium- ruthenium alloys with ultralow magnetic susceptibility.

    Science.gov (United States)

    Li, H F; Zhou, F Y; Li, L; Zheng, Y F

    2016-04-19

    In the present study, novel MRI compatible zirconium-ruthenium alloys with ultralow magnetic susceptibility were developed for biomedical and therapeutic devices under MRI diagnostics environments. The results demonstrated that alloying with ruthenium into pure zirconium would significantly increase the strength and hardness properties. The corrosion resistance of zirconium-ruthenium alloys increased significantly. High cell viability could be found and healthy cell morphology observed when culturing MG 63 osteoblast-like cells and L-929 fibroblast cells with zirconium-ruthenium alloys, whereas the hemolysis rates of zirconium-ruthenium alloys are zirconium-ruthenium alloys (1.25 × 10(-6) cm(3)·g(-1)-1.29 × 10(-6) cm(3)·g(-1) for zirconium-ruthenium alloys) are ultralow, about one-third that of Ti-based alloys (Ti-6Al-4V, ~3.5 × 10(-6) cm(3)·g(-1), CP Ti and Ti-6Al-7Nb, ~3.0 × 10(-6) cm(3)·g(-1)), and one-sixth that of Co-Cr alloys (Co-Cr-Mo, ~7.7 × 10(-6) cm(3)·g(-1)). Among the Zr-Ru alloy series, Zr-1Ru demonstrates enhanced mechanical properties, excellent corrosion resistance and cell viability with lowest magnetic susceptibility, and thus is the optimal Zr-Ru alloy system as therapeutic devices under MRI diagnostics environments.

  15. Prediction of Ba, Mn and Zn for tropical soils using iron oxides and magnetic susceptibility

    Science.gov (United States)

    Marques Júnior, José; Arantes Camargo, Livia; Reynaldo Ferracciú Alleoni, Luís; Tadeu Pereira, Gener; De Bortoli Teixeira, Daniel; Santos Rabelo de Souza Bahia, Angelica

    2017-04-01

    Agricultural activity is an important source of potentially toxic elements (PTEs) in soil worldwide but particularly in heavily farmed areas. Spatial distribution characterization of PTE contents in farming areas is crucial to assess further environmental impacts caused by soil contamination. Designing prediction models become quite useful to characterize the spatial variability of continuous variables, as it allows prediction of soil attributes that might be difficult to attain in a large number of samples through conventional methods. This study aimed to evaluate, in three geomorphic surfaces of Oxisols, the capacity for predicting PTEs (Ba, Mn, Zn) and their spatial variability using iron oxides and magnetic susceptibility (MS). Soil samples were collected from three geomorphic surfaces and analyzed for chemical, physical, mineralogical properties, as well as magnetic susceptibility (MS). PTE prediction models were calibrated by multiple linear regression (MLR). MLR calibration accuracy was evaluated using the coefficient of determination (R2). PTE spatial distribution maps were built using the values calculated by the calibrated models that reached the best accuracy by means of geostatistics. The high correlations between the attributes clay, MS, hematite (Hm), iron oxides extracted by sodium dithionite-citrate-bicarbonate (Fed), and iron oxides extracted using acid ammonium oxalate (Feo) with the elements Ba, Mn, and Zn enabled them to be selected as predictors for PTEs. Stepwise multiple linear regression showed that MS and Fed were the best PTE predictors individually, as they promoted no significant increase in R2 when two or more attributes were considered together. The MS-calibrated models for Ba, Mn, and Zn prediction exhibited R2 values of 0.88, 0.66, and 0.55, respectively. These are promising results since MS is a fast, cheap, and non-destructive tool, allowing the prediction of a large number of samples, which in turn enables detailed mapping of

  16. Detection of coal combustion products in stream sediments by chemical analysis and magnetic-susceptibility measurements

    Energy Technology Data Exchange (ETDEWEB)

    Franciskovic-Bilinski, S. [Rudjer Boskovic Institute, Zagreb (Croatia)

    2008-02-15

    Coal slag and ash, obtained from burning coal in a textile factory in Duga Resa (Croatia) was discharged directly into the Mreznica River for 110 y (1884-1994), from where it travelled to the Korana River and further to the Kupa River at Karlovac, a total of about 50 km from its source. Of 54 elements determined by inductively coupled plasma mass spectrometry (ICP-MS) in the {lt}2 mm sediment fraction, a number of anomalously high levels were recorded. The geoaccumulation index (I{sub geo}) for the anomalous elements were: Hg (1.88), B (4.05), Na (1.44). Al (2.05), V (1.65), Cr (1.20), Fe (1.18), Ni (2.10), Cu (2.37), Sr (0.97), Zr (3.27), Mo (3.34) and U (4.03). Low-field magnetic susceptibility (MS) was measured for each sample. The I{sub geo} for MS in the anomalous region is 5.85. Correlation analysis showed good correlation ({gt}0.90) of MS with: B (0.96), U (0.95), Zr (0.94), Sr (0.93), Na (0.92), Mo (0.92) and Ni (0.90). Cluster analysis of R-modality indicates that MS is linked to B, Mo, Na and U. Low correlation of MS with Fe (0.36) suggests that Fe in stream sediments is not in a ferromagnetic form. Neither maghemite, nor magnetite phases were identified by X-ray diffraction (XRD) in the sediments. Low-field magnetic susceptibility provides an indicator of contamination of river sediments by transported coal slag and ash, although it cannot be prescribed to a single element.

  17. Evolution of Cu-Zn-Si oxide catalysts in the course of reduction and reoxidation as studied by in situ X-ray diffraction analysis, transmission electron microscopy, and magnetic susceptibility methods

    NARCIS (Netherlands)

    Minyukova, T.P.; Shtertser, N.V.; Khassin, A.A.; Plyasova, L.M.; Kustova, G.N.; Zaikovskii, V.I.; Shvedenkov, Y.G.; Baronskaya, N.A.; van den Heuvel, J.C.; Kuznetsova, A.V.; Davydova, L.P.; Yur'eva, T.M.

    2008-01-01

    The reduced and reoxidized Cu-Zn-Si oxide catalysts as layered copper-zinc hydroxo silicates with the zincsilite structure were studied using in situ and ex situ X-ray diffraction analysis, transmission electron microscopy, and the temperature dependence of magnetic susceptibility. The catalysts wer

  18. Time-Dependent Nonlinear Optical Susceptibility of an Out-of-Equilibrium Soft Material

    Science.gov (United States)

    Ghofraniha, Neda; Conti, Claudio; Ruocco, Giancarlo; Zamponi, Francesco

    2009-01-01

    We investigate the time-dependent nonlinear optical absorption of a clay dispersion (Laponite) in an organic dye (rhodamine B) water solution displaying liquid-arrested state transition. Specifically, we determine the characteristic time τD of the nonlinear susceptibility buildup due to the Soret effect. By comparing τD with the relaxation time provided by standard dynamic light scattering measurements we report on the decoupling of the two collective diffusion times at the two very different length scales during the aging of the out-of-equilibrium system. With this demonstration experiment we also show the potentiality of nonlinear optics measurements in the study of the late stage of arrest in soft materials.

  19. Dependence of polar hole density on magnetic and solar conditions

    Science.gov (United States)

    Hoegy, W. R.; Grebowsky, J. M.

    1991-01-01

    Electron densities from the Langmuir probes on the Atmospheric Explorer C and Dynamics Explorer 2 are used for analyzing the behavior of the high-altitude night-side F region polar hole as a function of solar and magnetic activity and of universal time (UT). The polar region of invariant latitude from 70 deg to 80 deg and MLT from 22 to 03 hours is examined. The strongest dependencies are observed in F10.7 and UT; a strong hemispherical difference due to the offset of the magnetic poles from the earth's rotation axis is observed in the UT dependence of the ionization hole. A seasonal variation in the dependence of ion density on solar flux is indicated, and an overall asymmetry in the density level between hemispheres is revealed, with the winter-hole density about a factor of 10 greater in the north than in the south.

  20. Effect of suction-dependent soil deformability on landslide susceptibility maps

    Science.gov (United States)

    Lizarraga, Jose J.; Buscarnera, Giuseppe; Frattini, Paolo; Crosta, Giovanni B.

    2016-04-01

    This contribution presents a physically-based, spatially-distributed model for shallow landslides promoted by rainfall infiltration. The model features a set of Factor of Safety values aimed to capture different failure mechanisms, namely frictional slips with limited mobility and flowslide events associated with the liquefaction of the considered soils. Indices of failure associated with these two modes of instability have been derived from unsaturated soil stability principles. In particular, the propensity to wetting-induced collapse of unsaturated soils is quantified through the introduction of a rigid-plastic model with suction-dependent yielding and strength properties. The model is combined with an analytical approach (TRIGRS) to track the spatio-temporal evolution of soil suction in slopes subjected to transient infiltration. The model has been tested to reply the triggering of shallow landslides in pyroclastic deposits in Sarno (1998, Campania Region, Southern Italy). It is shown that suction-dependent mechanical properties, such as soil deformability, have important effects on the predicted landslide susceptibility scenarios, resulting on computed unstable zones that may encompass a wide range of slope inclinations, saturation levels, and depths. Such preliminary results suggest that the proposed methodology offers an alternative mechanistic interpretation to the variability in behavior of rainfall-induced landslides. Differently to standard methods the explanation to this variability is based on suction-dependent soil behavior characteristics.

  1. MR susceptibility imaging

    Science.gov (United States)

    Duyn, Jeff

    2013-04-01

    This work reviews recent developments in the use of magnetic susceptibility contrast for human MRI, with a focus on the study of brain anatomy. The increase in susceptibility contrast with modern high field scanners has led to novel applications and insights into the sources and mechanism contributing to this contrast in brain tissues. Dedicated experiments have demonstrated that in most of healthy brain, iron and myelin dominate tissue susceptibility variations, although their relative contribution varies substantially. Local variations in these compounds can affect both amplitude and frequency of the MRI signal. In white matter, the myelin sheath introduces an anisotropic susceptibility that has distinct effects on the water compartments inside the axons, between the myelin sheath, and the axonal space, and renders their signals dependent on the angle between the axon and the magnetic field. This offers opportunities to derive tissue properties specific to these cellular compartments.

  2. Temperature-Dependent Giant Magnetoimpedance Effect in Amorphous Soft Magnets

    Science.gov (United States)

    Kurniawan, M.; Roy, R. K.; Panda, A. K.; Greve, D. W.; Ohodnicki, P.; McHenry, M. E.

    2014-12-01

    Giant magnetoimpedance (GMI)-based devices offer potential as next-generation low-cost, flexible, ultrasensitive sensors. They can be used in applications that include current sensors, field sensors, stress sensors, and others. Challenging applications involve operation at high temperatures, and therefore studies of GMI temperature dependence and performance of soft magnetic materials are needed. We present a high-temperature GMI study on an amorphous soft magnetic microwire from room temperature to 560°C. The GMI ratio was observed to be nearly constant at ˜86% at low temperatures and to decrease rapidly at ˜290°C, finally reaching a near-zero value at 500°C. The rapid drop in GMI ratio at 290°C is associated with a reduction in the long-range ferromagnetic order as measured by the spontaneous magnetization ( M) at the Curie temperature ( T c). We also correlated the impedance with the magnetic properties of the material. From room temperature to 290°C, the impedance was found to be proportional to the square root of the magnetization to magnetic anisotropy ratio. Lastly, M( T) has been fit using a Handrich-Kobe model, which describes the system with a modified Brillouin function and an asymmetrical distribution of exchange interactions. We infer that the structural fluctuations of the amorphous phase result in a relatively small asymmetry in the fluctuation parameters.

  3. The magnetic susceptibility, specific heat and dielectric constant of hexagonal YMnO3, LuMnO3 and ScMnO3

    Science.gov (United States)

    Tomuta, D. G.; Ramakrishnan, S.; Nieuwenhuys, G. J.; Mydosh, J. A.

    2001-05-01

    We report the magnetic susceptibility, specific heat and dielectric constant for high-purity polycrystalline samples of three hexagonal manganites: YMnO3, LuMnO3 and ScMnO3. These materials can exhibit a ferroelectric transition at very high temperatures (TFE>700 K). At lower temperatures there is magnetic ordering of the frustrated Mn3+ spins (S = 2) on a triangular Mn lattice (YMnO3: TN = 71 K LuMnO3: TN = 90 K and ScMnO3: TN = 130 K). The transition is characterized by a sharp kink in the magnetic susceptibility at TN below which it continues to increase due to the frustration on the triangular lattice. The specific heat shows one clear continuous phase transition at TN, which is independent of external magnetic field up to 9 T with an entropy content as expected for Mn3+ ions. The temperature-dependent dielectric constant displays a distinct anomaly at TN.

  4. Frequency-Dependent Properties of Magnetic Nanoparticle Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Majetich, Sara [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    2016-05-17

    In the proposed research program we will investigate the time- and frequency-dependent behavior of ordered nanoparticle assemblies, or nanoparticle crystals. Magnetostatic interactions are long-range and anisotropic, and this leads to complex behavior in nanoparticle assemblies, particularly in the time- and frequency-dependent properties. We hypothesize that the high frequency performance of composite materials has been limited because of the range of relaxation times; if a composite is a dipolar ferromagnet at a particular frequency, it should have the advantages of a single phase material, but without significant eddy current power losses. Arrays of surfactant-coated monodomain magnetic nanoparticles can exhibit long-range magnetic order that is stable over time. The magnetic domain size and location of domain walls is governed not by structural grain boundaries but by the shape of the array, due to the local interaction field. Pores or gaps within an assembly pin domain walls and limit the domain size. Measurements of the magnetic order parameter as a function of temperature showed that domains can exist at high temoerature, and that there is a collective phase transition, just as in an exchange-coupled ferromagnet. Dipolar ferromagnets are not merely of fundamental interest; they provide an interesting alternative to exchange-based ferromagnets. Dipolar ferromagnets made with high moment metallic particles in an insulating matrix could have high permeability without large eddy current losses. Such nanocomposites could someday replace the ferrites now used in phase shifters, isolators, circulators, and filters in microwave communications and radar applications. We will investigate the time- and frequency-dependent behavior of nanoparticle crystals with different magnetic core sizes and different interparticle barrier resistances, and will measure the magnetic and electrical properties in the DC, low frequency (0.1 Hz - 1 kHz), moderate frequency (10 Hz - 500

  5. The magnetic susceptibility measurements of turbidity current sediments from Fuxian Lake of Yunnan Province and their correlations with earthquakes

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    This paper has advanced a new method for determining historical earthquakes. Its object of study is lake sediments. The research method is environmental magnetism represented by susceptibility. The purpose is extracting historical earthquake informations from lake sediments to explore the correlation between the turbidity current sediments initiated by the earthquakes and historical earthquakes round Fuxian Lake.

  6. Heliocentric distance dependence of the interplanetary magnetic field

    Science.gov (United States)

    Behannon, K. W.

    1978-01-01

    Numerous spacecraft measurements bearing on the heliocentric distance dependencies of both large- and small-scale properties of the interplanetary magnetic field (IMF) are assembled and compared. These data tend to indicate that the average of the radial field component varies as the inverse square of distance. However, the azimuthal component is rather strongly a function of time, being influenced by both the time-dependent solar wind speed and the evolution of the source field at the sun. Thus, unless the solar wind speed dependence is taken into account, individual sets of measurements by a single spacecraft give an azimuthal component gradient which is steeper than the inverse distance dependence predicted from the Parker spiral model. A least squares fit to the composite (five spacecraft) solar rotation average data set gives a result close to the inverse distance dependence. Preliminary Helios results suggest general consistency with the spiral model.

  7. Rock magnetic properties, magnetic susceptibility, and organic geochemistry comparison in core LZ1029-7 Lake El'gygytgyn, Far Eastern Russia

    Directory of Open Access Journals (Sweden)

    K. J. Murdock

    2012-09-01

    Full Text Available Susceptibility measurements performed on initial short (3–16 m cores taken from Lake El'gygytgyn exhibited a large range in values. This observation led to the suggestion of widespread magnetite dissolution within the sediments due to anoxic conditions within the lake. Rock magnetic properties and their comparison with magnetic susceptibility, Total Organic Carbon (TOC, and bulk δ13Corg proxies in core LZ1029-7 provide an insight into the character of the magnetic minerals present within the lake and can further the understanding of processes that may be present in the newer long core sediments Susceptibility measurements (χ of discrete samples corroborate the two order of magnitude difference seen in previous continuous susceptibility measurements (κ, correlating high values with interglacial periods and low values with glacial intervals. Hysteresis parameters defined the majority of the magnetic material to be magnetite of PSD size. TOC values increase while δ13Corg values decrease in one section of LZ1029-7, which is defined as the Last Glacial Maximum (LGM, and help confine the age of the core to approximately 62 kyr. Increases in TOC during the most recent glacial interval suggest increased preservation of organic carbon during these times High TOC and low magnetic susceptibility during the LGM support the theory of perennial ice cover during glacial periods, which would lead to lake stratification and therefore anoxic bottom water conditions. Low temperature magnetic measurements also confirmed the presence of magnetite, but also indicated titanomagnetite, siderite and/or rhodochrosite, and vivianite were present. The latter three minerals are found only in anoxic environments, and further support the notion of magnetite dissolution.

  8. Rock magnetic properties, magnetic susceptibility, and organic geochemistry comparison in core LZ1029-7 Lake El'gygytgyn, Russia Far East

    Directory of Open Access Journals (Sweden)

    K. J. Murdock

    2013-02-01

    Full Text Available Susceptibility measurements performed on initial short (~ 16 m cores PG1351 taken from Lake El'gygytgyn exhibited a large range in values. This observation led to the suggestion of widespread magnetite dissolution within the sediments due to anoxic conditions within the lake. Rock magnetic properties and their comparison with magnetic susceptibility, total organic carbon (TOC, and bulk δ13Corg proxies in core LZ1029-7, taken from the same site as the previously drilled PG1351, provide an insight into the character of the magnetic minerals present within the lake and can further the understanding of processes that may be present in the newer long core sediments. Susceptibility measurements (χ of discrete samples corroborate the two order of magnitude difference seen in previous continuous susceptibility measurements (κ, correlating high values with interglacial periods and low values with glacial intervals. Hysteresis parameters indicate that the majority of the magnetic material to be magnetite of PSD size. TOC values increase while δ13Corg values decrease in one section of LZ1029-7, which is defined as the Last Glacial Maximum (LGM, and help confine the age of the core to approximately 62 ka. Increases in TOC during the most recent glacial interval suggest increased preservation of organic carbon during this period. High TOC and low magnetic susceptibility during the LGM support the theory of perennial ice cover during glacial periods, which would lead to lake stratification and therefore anoxic bottom water conditions. Low temperature magnetic measurements confirmed the presence of magnetite, but also indicated titanomagnetite and possibly siderite, rhodochrosite, and/or vivianite were present. The latter three minerals are found only in anoxic environments, and further support the notion of magnetite dissolution.

  9. Magnetic susceptibility of dust-loaded leaves as a proxy of traffic-related heavy metal pollution in Kathmandu city, Nepal

    Science.gov (United States)

    Gautam, Pitambar; Blaha, Ulrich; Appel, Erwin

    Dust-loaded tree leaves from Kathmandu have been analyzed for magnetic susceptibility ( χ) and heavy metal (HM) contents. For 221 samples of leaves of cypress (mainly Cupressus corneyana), silky oak ( Grevillea robusta) and bottlebrush ( Callistemon lanceolatus), χ has a range of (0.01-54)×10 -8 m 3 kg -1 with a median of about 10.0×10 -8 m 3 kg -1. Trees situated close to the busy road intersections, near the main bus station and sectors of roads with steep slope yield elevated susceptibility. Chemical analysis of 20 samples of varying susceptibility by atomic absorption spectrometry yields the following maximum HM contents: Fe (1.3 wt%), Mn (281.9 ppm), Zn (195.2 ppm), Cu (41.5 ppm), Pb (38.4 ppm), Ni (8.1 ppm), Cr (6.4 ppm), Co (4.1 ppm) and Cd (1.2 ppm). The logarithmic susceptibility on dry mass basis ( χ) shows significant linear relationship with HM contents: Pearson's correlation coefficient r>0.8 with Zn, Fe, Cr; r>0.7 with Mn, Cu; r>0.6 with Pb, Ni. Magnetic phases are of soft (magnetite/maghemite) and hard (hematite) coercivities. Microscopy of magnetic extracts reveals spherules (mostly of 2-20 μm diameter) originated from vehicle exhausts through the combustion process as well as crystalline grains of lithogenic origin. The dust accumulation in leaves took place mainly after monsoon (beginning of October 2001) till the sampling period (first half of February 2002). Despite the dependence of susceptibility and HM contents on a variety of spatial and temporal factors (amount of particulate matter (PM), efficiency of deposition/removal of PM by wind, precipitation, birds etc.), a significant correlation of susceptibility to HM implies that the former serves as an effective proxy of metallic pollution. Hence, susceptibility-based bio-monitoring technique is recommended as an economic and rapid tool for assessment of environmental pollution in urban areas like Kathmandu.

  10. Constraints on deformation of the Southern Andes since the Cretaceous from anisotropy of magnetic susceptibility

    Science.gov (United States)

    Maffione, Marco; Hernandez-Moreno, Catalina; Ghiglione, Matias C.; Speranza, Fabio; van Hinsbergen, Douwe J. J.; Lodolo, Emanuele

    2015-12-01

    The southernmost segment of the Andean Cordillera underwent a complex deformation history characterized by alternation of contractional, extensional, and strike-slip tectonics. Key elements of southern Andean deformation that remain poorly constrained, include the origin of the orogenic bend known as the Patagonian Orocline (here renamed as Patagonian Arc), and the exhumation mechanism of an upper amphibolite facies metamorphic complex currently exposed in Cordillera Darwin. Here, we present results of anisotropy of magnetic susceptibility (AMS) from 22 sites in Upper Cretaceous to upper Eocene sedimentary rocks within the internal structural domain of the Magallanes fold-and-thrust belt in Tierra del Fuego (Argentina). AMS parameters from most sites reveal a weak tectonic overprint of the original magnetic fabric, which was likely acquired upon layer-parallel shortening soon after sedimentation. Magnetic lineation from 17 sites is interpreted to have formed during compressive tectonic phases associated to a continuous N-S contraction. Our data, combined with the existing AMS database from adjacent areas, show that the Early Cretaceous-late Oligocene tectonic phases in the Southern Andes yielded continuous contraction, variable from E-W in the Patagonian Andes to N-S in the Fuegian Andes, which defined a radial strain field. A direct implication is that the exhumation of the Cordillera Darwin metamorphic complex occurred under compressive, rather than extensional or strike-slip tectonics, as alternatively proposed. If we agree with recent works considering the curved Magallanes fold-and-thrust belt as a primary arc (i.e., no relative vertical-axis rotation of the limbs occurs during its formation), then other mechanisms different from oroclinal bending should be invoked to explain the documented radial strain field. We tentatively propose a kinematic model in which reactivation of variably oriented Jurassic faults at the South American continental margin controlled

  11. Mud crab susceptibility to disease from white spot syndrome virus is species-dependent

    Directory of Open Access Journals (Sweden)

    Sritunyalucksana Kallaya

    2010-11-01

    susceptible than S. paramamosain. Based on our single-challenge and serial challenge results, and on previous published work showing that S. serrata is relatively unaffected by WSSV infection, we propose that susceptibility to white spot disease in the genus Scylla is species-dependent and may also be dose-history dependent. In practical terms for shrimp farmers, it means that S. olivacea and S. paramamosain may pose less threat as WSSV carriers than S. serrata. For crab farmers, our results suggest that rearing of S. serrata would be a better choice than S. paramamosain or S. olivacea in terms of avoiding losses from seasonal outbreaks of white spot disease.

  12. Folic acid induces salicylic acid-dependent immunity in Arabidopsis and enhances susceptibility to Alternaria brassicicola.

    Science.gov (United States)

    Wittek, Finni; Kanawati, Basem; Wenig, Marion; Hoffmann, Thomas; Franz-Oberdorf, Katrin; Schwab, Wilfried; Schmitt-Kopplin, Philippe; Vlot, A Corina

    2015-08-01

    Folates are essential for one-carbon transfer reactions in all organisms and contribute, for example, to de novo DNA synthesis. Here, we detected the folate precursors 7,8-dihydropteroate (DHP) and 4-amino-4-deoxychorismate (ADC) in extracts from Arabidopsis thaliana plants by Fourier transform ion cyclotron resonance-mass spectrometry. The accumulation of DHP, but not ADC, was induced after infection of plants with Pseudomonas syringae delivering the effector protein AvrRpm1. Application of folic acid or the DHP precursor 7,8-dihydroneopterin (DHN) enhanced resistance in Arabidopsis to P. syringae and elevated the transcript accumulation of the salicylic acid (SA) marker gene pathogenesis-related1 in both the treated and systemic untreated leaves. DHN- and folic acid-induced systemic resistance was dependent on SA biosynthesis and signalling. Similar to SA, folic acid application locally enhanced Arabidopsis susceptibility to the necrotrophic fungus Alternaria brassicicola. Together, the data associate the folic acid pathway with innate immunity in Arabidopsis, simultaneously activating local and systemic SA-dependent resistance to P. syringae and suppressing local resistance to A. brassicicola.

  13. Additive susceptibility to insulin-dependent diabetes conferred by HLA-DQB1 and insulin genes.

    Science.gov (United States)

    She, J X; Bui, M M; Tian, X H; Muir, A; Wakeland, E K; Zorovich, B; Zhang, L P; Liu, M C; Thomson, G; Maclaren, N K

    1994-01-01

    Several genomic polymorphisms at the insulin (INS) gene and its flanking regions were analyzed in 197 unrelated Caucasian patients affected by insulin-dependent diabetes (IDDM) and 159 ethnically matched, normal controls ascertained from the South-Eastern United States. We found that the frequency of homozygotes for the common variant at the insulin gene was significantly increased in the diabetic population (RR = 2.0, p INS gene. We determined the HLA-DQB1 genotypes by denaturing gradient gel electrophoresis (DGGE) and/or sequence-specific primers (SSP) techniques to assess the possible interactions between INS and HLA. DQB1*0302 had the strongest predisposing effect on IDDM susceptibility (RR = 9.3) and DQB1*0602 the strongest protective effect (RR = 0.02). However, a significant predisposing effect of DQB1*0201 could be demonstrated only after removal of the effects of DQB1*0302 and DQB1*0602. Analyses of the genotypes revealed that all genotypes containing 0602 were protective and that the heterozygous genotype 0201/0302 and homozygous genotype 0302/0302 confer the highest risk (RR = 20.9 and 12.9 respectively). However, heterozygous genotypes 0302/X (X excludes 0201, 0302 and 0602) have a significantly lower predisposing risk. Similarly, there is heterogeneity in risk between predisposing 0201/0201 homozygous individuals and protective 0201/X individuals. When subjects were stratified by HLA genotypes, the relative risks conferred by INS did not vary, thus suggesting that the susceptibility effects conferred by HLA and INS are additive rather than interactive.

  14. Metastable Zr-Nb alloys for spinal fixation rods with tunable Young's modulus and low magnetic resonance susceptibility.

    Science.gov (United States)

    Zhao, X L; Li, L; Niinomi, M; Nakai, M; Zhang, D L; Suryanarayana, C

    2017-10-15

    Good ductility, low magnetic susceptibility, and tunable Young's modulus are highly desirable properties for materials usage as spinal fixation rods. In this study, the effects of niobium content on the microstructure, magnetic susceptibility, and mechanical properties of Zr-xNb (13≤x≤23wt%) alloys were investigated. For the Zr-15Nb and Zr-17Nb alloys, a remarkable increase in Young's modulus was achieved due to the occurrence of deformation-induced ω phase transformation. This was the result of the competition of two factors associated with the Nb content: an increase of the stability of β phase and a decrease of the amount of athermal ω phase with increasing Nb content. When the Nb content was 15% or 17%, the amount of deformation-induced ω phase was maximum. Moreover, the magnetic susceptibility decreased with the deformation-induced β→ω phase transformation, and the Zr-17Nb alloy with apparent kink bands exhibited a smaller amount of springback than the Zr-15Nb alloy with {332} 〈113〉 mechanical twins. Furthermore, the ions released from the Zr-xNb alloys in accelerated immersion tests were at a very low level. The combination of low initial Young's modulus, and its remarkable variation induced by deformation, low magnetic susceptibility, good ductility, and smaller springback make the Zr-17Nb alloy a potential candidate for spinal fixation rods. For the rods of spinal fixation devices, it is important but difficult to lower the springback for bending formativeness while keeping the low initial Young's modulus for biocompatibility and lower the magnetic susceptibility for postoperative examination simultaneously. In this study, Zr-17Nb alloy was successfully developed via deformation-induced ω phase transformation during loading, simultaneously meeting the abovementioned properties for spinal fixation rods. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  15. Temperature-dependent magnetic EXAFS investigation of Gd

    CERN Document Server

    Wende, H; Poulopoulos, P N; Rogalev, A; Goulon, J; Schlagel, D L; Lograsso, T A; Baberschke, K

    2001-01-01

    Magnetic EXAFS (MEXAFS) is the helicity-dependent counterpart of the well-established EXAFS technique. By means of MEXAFS it is possible not only to analyze the local magnetic structure but also to learn about magnetic fluctuations. Here we present the MEXAFS of a Gd single crystal at the L sub 3 sub , sub 2 -edges in the temperature range of 10-250 K. For the first time MEXAFS was probed over a large range in reduced temperature of 0.04<=T/T sub C<=0.85 with T sub C =293 K. We show that the vibrational damping described by means of a Debye temperature of theta sub D =160 K must be taken into account for the spin-dependent MEXAFS before analyzing magnetic fluctuations. For a detailed analysis of the MEXAFS and the EXAFS, the experimental data are compared to ab initio calculations. This enables us to separate the individual single- from the multiple-scattering contributions. The MEXAFS data have been recorded at the ID 12A beamline of the European Synchrotron Radiation Facility (ESRF). To ensure that th...

  16. Temperature dependence of magnetic anisotropies in ultra-thin films

    CERN Document Server

    Hucht, A

    1999-01-01

    shown that in contrast to other works the temperature driven spin reorientation transition in the monolayer is discontinuous also in the simulations, whereas in general it is continuous for the bilayer. Consequently the molecular field theory and the Monte Carlo simulations agree qualitatively. Exemplary for thicker films the influence of an external magnetic field is investigated in the bilayer, furthermore the effective anisotropies K sub n (T) of the phenomenological Landau theory are calculated numerically for the microscopic model. Analytic expressions for the dependence of the anisotropies K sub n (T) on the parameters of the model are obtained by the means of perturbation theory, which lead to a deeper understanding of the spin reorientation transition. Accordingly to this the origin for the spin reorientation transition lies in the differing temperature dependence of the dipolar and spin-orbit parts of the K sub n (T). Additionally the magnetization in the surface of the film decreases more rapidly wi...

  17. Magnetic susceptibility of Dirac fermions, Bi-Sb alloys, interacting Bloch fermions, dilute nonmagnetic alloys, and Kondo alloys

    Science.gov (United States)

    Buot, Felix A.; Otadoy, Roland E. S.; Rivero, Karla B.

    2017-03-01

    Wide ranging interest in Dirac Hamiltonian is due to the emergence of novel materials, namely, graphene, topological insulators and superconductors, the newly-discovered Weyl semimetals, and still actively-sought after Majorana fermions in real materials. We give a brief review of the relativistic Dirac quantum mechanics and its impact in the developments of modern physics. The quantum band dynamics of Dirac Hamiltonian is crucial in resolving the giant diamagnetism of bismuth and Bi-Sb alloys. Quantitative agreement of the theory with the experiments on Bi-Sb alloys has been achieved, and physically meaningful contributions to the diamagnetism has been identified. We also treat relativistic Dirac fermion as an interband dynamics in uniform magnetic fields. For the interacting Bloch electrons, the role of translation symmetry for calculating the magnetic susceptibility avoids any approximation to second order in the field. The expressions for magnetic susceptibility of dilute nonmagnetic alloys give a firm theoretical foundation of the empirical formulas used in fitting experimental results. The unified treatment of all the above calculations is based on the lattice Weyl-Wigner formulation of discrete phase-space quantum mechanics. For completeness, the magnetic susceptibility of Kondo alloys is also given since Dirac fermions in conduction band and magnetic impurities exhibit Kondo effect.

  18. Irreversibility line and magnetic field dependence of the critical current in superconducting MgB sub 2 bulk samples

    CERN Document Server

    Gioacchino, D D; Tripodi, P; Grimaldi, G

    2003-01-01

    The third harmonic components of the ac susceptibility of MgB sub 2 bulk samples have been measured as a function of applied magnetic fields, together with standard magnetization cycles. The irreversibility line (IL) of the magnetic field has been extracted from the onset of the third harmonic components. Using a (1 - t) supalpha glass/liquid best fit where alpha 1.27 IL shows a coherent length xi divergence with exponent nu = 0.63, which indicates a 3D behaviour. Moreover, using the numerical solution of the non-linear magnetic diffusion equation, considering the creep model in a 3D vortex glass, a good description of the vortex dynamics has been obtained. The behaviour of the magnetization amplitude (approx Hz) and the ac susceptibility signals (kHz), at different applied magnetic fields, 3.5 T < H sub d sub c < 4.5 T, and at the reduced temperature 0.86 < t < 0.93 (T = 22 K), shows that the superconducting dynamic response of vortices in the MgB sub 2 samples is not evidently dependent on the f...

  19. Magnetic susceptibility of MnZn and NiZn soft ferrites using Laplace transform and the Routh-Hurwitz criterion

    Energy Technology Data Exchange (ETDEWEB)

    Fano, Walter Gustavo, E-mail: gustavo.gf2005@gmail.co [Faculty of Engineering, National University of the Patagonia San Juan Bosco, Ruta 1 km4, (9000) Comodoro Rivadavia, Chubut (Argentina); Boggi, Silvina; Razzitte, Adrian Cesar [Faculty of Engineering, University of Buenos Aires, Av. Paseo Colon 850, 1063 Buenos Aires (Argentina)

    2011-06-15

    This paper is devoted to study the Routh-Hurwitz stability criterion from the MnZn and NiZn soft ferrites using a phenomenological model with the gyromagnetic spin contribution and domain wall contribution. The magnetodynamic equation and the harmonic oscillator equation have been used to obtain the domain walls and the spin contribution of the magnetic susceptibility. The ferrite materials have been considered as linear, time invariant, isotropic and homogeneous, and the magnetization vector is proportional to the magnetic field vector. The resulting expression of the magnetization in time domain of both ferrites under study has been obtained by mean of the inverse Laplace transformation applying the residue method. The poles of the magnetic susceptibility have negative real parts, which ensures that the response decays exponentially to zero as the time increase. The degree of the numerator's polynomial of the magnetic susceptibility is less than the degree of denominator's polynomial in the magnetic susceptibility function: and the poles are located in the half left s-plane. Then the system is bounded-input, bounded-output (BIBO), and the results agree with the Routh-Hurwitz stability criterion for the MnZn and NiZn soft ferrites. - Research Highlights: Laplace transform of the magnetic susceptibility of the MnZn and NiZn soft ferrites. Routh-Hurwitz stability criterion of magnetic materials. Bode plot of magnetic susceptibility. Inverse Laplace transform using residue theorem.

  20. Electronic structure and magnetic properties of solids

    Science.gov (United States)

    Savrasov, Sergej Y.; Toropova, Antonina; Katsnelson, Mikhail I.; Lichtenstein, Alexander I.; Antropov, Vladimir; Kotliar, Gabriel

    2005-05-01

    We review basic computational techniques for simulations of various magnetic properties of solids. Several applications to compute magnetic anisotropy energy, spin wave spectra, magnetic susceptibilities and temperature dependent magnetisations for a number of real systems are presented for illustrative purposes.

  1. Electronic structure and magnetic properties of solids

    OpenAIRE

    Savrasov, S. Y.; Toropova, A.; Katsnelson, M. I.; Lichtenstein, A. I.; Antropov, V.; Kotliar, G.

    2005-01-01

    We review basic computational techniques for simulations of various magnetic properties of solids. Several applications to compute magnetic anisotropy energy, spin wave spectra, magnetic susceptibilities and temperature dependent magnetisations for a number of real systems are presented for illustrative purposes.

  2. Geomagnetic field intensity and quantitative paleorainfall reconstruction from Chinese loess using 10Be and magnetic susceptibility

    Science.gov (United States)

    Beck, W.; zhou, W.; Li, C.; Wu, Z.; White, L.; Xian, F.

    2011-12-01

    7Be is produced in the atmosphere by cosmic ray spallation reactions and carried to the ground attached to aerosols, usually encapsulated in rain or snow. Numerous studies have shown that its flux to the ground is proportional to rainfall amount. Unfortunately, with a half life of only a few weeks, this observation has little relevance for reconstruction past rainfall amounts in paleosoils. Fortunately, 7Be has a long-lived sister isotope (10Be) with a half life of ~1.5 Ma which can be used for such purposes. There are a number of complications, however. First, 10Be atmospheric production rate changes when the geomagnetic field intensity changes. Secondly, 10Be half life is long enough that 10Be which fell to the ground attached to dust some time in the past can become resuspended, meaning that there are two sources of 10Be, one meteoric, and the other recycled aeolian dust. Fortunately, we have found a method to deconvolute this knotty situation and have applied it to soils of the Chinese Loess Plateau, allowing us to reconstruct records of both geomagnetic field intensity and paleorainfall. To do so, we use the additional parameters magnetic susceptibility and coercivity to help define the inherited amount of each component, and to define what fraction of the variations in 10Be are associated with magnetic field fluctuations, versus that linked to rainfall variations. We also use a sediment age/depth model to convert 10Be concentration to 10Be flux, and finally, we use the modern 7Be vs. rainfall relationship and 10Be/7Be atmospheric production rate ratio to calculate quantitative paleorainfall rates. We have used these techniques to generate several such records ranging from the Holocene to MIS13 (Circa 525 ka BP), and will compare some of these to U-series dated speleothem records of δ18O.

  3. Granular Responses of GdBa2Cu3O7-δ Using ac Magnetic Susceptibility Measurement under ac and dc Magnetic Fields

    Science.gov (United States)

    Namuco, S. B.; Lao, M. L.; Sarmago, R. V.

    Granularity of bulk materials has a great impact on the characterization of superconductors as well as its path towards room temperature applications. Bulk GdBCO that has crystal formation and Tc close to YBCO were fabricated using the conventional solid state route method. AC magnetic susceptibility measurement is done on the sample to observe the granular responses brought about by small magnetic field values that is superimposed with DC magnetic field. Results show that compared to YBCO, GdBCO show more sensitive behaviour with the addition of DC magnetic field. It is shown in the results that abrupt response in the AC loss peaks observed in χ" is more prominent in GdBCO even at lower applied magnetic fields.

  4. Magnetic susceptibility as an indicator to paleo-environmental pollution in an urban lagoon near Istanbul city

    Science.gov (United States)

    Alpar, Bedri; Unlu, Selma; Altinok, Yildiz; Ongen, Sinan

    2014-05-01

    For assessing anthropogenic pollution, magnetic susceptibility profiles and accompanying data were measured along three short cores recovered at the southern part of an urban lagoon; Kucukcekmece, Istanbul, Turkey. This marine inlet, connected to the Sea of Marmara by a very narrow channel, was used as a drinking water reservoir 40-50 years ago before it was contaminated by municipal, agricultural and industrial activities, mainly carried by three streams feeding the lagoon. The magnetic signals decrease gradually from the lake bottom towards the core base showing some characteristic anomalies. These signatures were tested as an environmental magnetic parameter against the lithological diversity (silici-clastic, total organic matter and carbonate), metal enrichments with larger variations (Pb, Mn, Zn, Ni, Co, Cr, U and Al) and probable hydrocarbon contamination. Mineral assemblage was determined by a computer driven X-ray diffractometer. The heavy metal concentrations and total petroleum hydrocarbons (TPH) were measured by ICP-MS and UVF spectrometry, respectively. Magnetic susceptibility shows slightly higher values in interlayers containing higher silici-clastic material and organic content which may suggest first-order changes in the relative supplies of terrigenous and biogenic materials. On the basis of cluster analyses, enhanced magnetic signals could be correlated with the elevated concentrations of Co, Zn, U, Pb and TPH along the cores. The Pb concentrations at the upper parts of the cores were higher than the "Severe Effect Level" and could pose a potential risk for living organisms. Greater amounts of organic carbon tend to accumulate in muddy sediments. In fact, there are a few studies reporting some relationship between enhanced magnetic signals and organic contamination mainly due to petroleum aromatic hydrocarbons. In conclusion, the magnetic susceptibility changes in sedimentary depositional environments could be used as a rapid and cost

  5. Size-dependent magnetic properties of branchlike nickel oxide nanocrystals

    Science.gov (United States)

    Liu, Dan; Li, Dongsheng; Yang, Deren

    2017-01-01

    Branchlike nickel oxide nanocrystals with narrow size distribution are obtained by a solution growth method. The size-dependent of magnetic properties of the nickel oxides were investigated. The results of magnetic characterization indicate that the NiO nanocrystals with size below 12.8 nm show very weak ferromagnetic state at room temperature due to the uncompensated spins. Both of the average blocking temperature (Tb) and the irreversible temperature (Tirr) increase with the increase of nanoparticle sizes, while both the remnant magnetization and the coercivity at 300 K increase with the decrease of the particle sizes. Moreover, the disappearance of two-magnon (2M) band and redshift of one-phonon longitudinal (1LO) and two-phonon LO in vibrational properties due to size reduction are observed. Compared to the one with the spherical morphological, it is also found that nano-structured nickel oxides with the branchlike morphology have larger remnant magnetization and the coercivity at 5 K due to their larger surface-to-volume ratio and greater degree of broken symmetry at the surface or the higher proportion of broken bonds.

  6. X-ray scattering and magnetic susceptibility study of doped CuGeO sub 3

    CERN Document Server

    Wang, Y J; Lamarra, S C; Chou, F C; Kim, Y J; Masuda, T; Tsukada, I; Uchinokura, K; Birgeneau, R J

    2003-01-01

    We report comprehensive synchrotron x-ray scattering and magnetic susceptibility studies of the doped spin-Peierls materials Cu sub 1 sub - sub x Zn sub x GeO sub 3 and CuGe sub 1 sub - sub y Si sub y O sub 3. Temperature versus dopant concentration phase diagrams are mapped out for both Zn and Si dopants. The phase diagrams of both Cu sub 1 sub - sub x Zn sub x GeO sub 3 and CuGe sub 1 sub - sub y Si sub y O sub 3 closely resemble that of Cu sub 1 sub - sub x Mg sub x GeO sub 3 , including the observation that the spin gap is established at a much higher temperature than the temperature at which the spin-Peierls dimerization attains long-range order. The spin-Peierls transitions in doped samples exhibit unusual phase transition behavior, characterized by highly rounded phase transitions, Lorentzian squared lineshapes, and very long relaxation times. Phenomenological explanations for these observations are given by considering the effects of competing random bond interactions as well as random fields generate...

  7. Magnetic Susceptibility as a Tool for Investigating Igneous Rocks—Experience from IODP Expedition 304

    Directory of Open Access Journals (Sweden)

    Roger C. Searle

    2008-07-01

    Full Text Available Continuous measurements of magnetic susceptibility have been commonly used on Ocean Drilling Program (ODP and Integrated Ocean Drilling Program (IODPexpeditions to study minor lithological variations (forexample, those related to climatic cycles in sedimentary rocks, but they have been less frequently used on igneous rocks, although important post-cruise studies have utilized them (e.g., Ildefonse and Pezard, 2001. Here I report its use (and that of the closely related electrical conductivity on IODP Expedition 304 to examine igneous crustal rocks. Expedition 304/305 targeted the Atlantis Massif, an oceanic core complex on the Mid-Atlantic Ridge, and recovered a suite of igneous rocks comprising mainly gabbros, troctolites, and some diabases (Blackman et al., 2006; Ildefonse et al., 2006, 2007; IODP Expeditions 304 and 305 Scientists, 2005. Shipboard measurements (on D/V JOIDES Resolution of physical properties were made to characterize lithological units and alteration products, to correlate cored material with down-hole logging data, and to interpret broader-scale geophysical data.

  8. Dynamic Susceptibility Contrast Magnetic Resonance Imaging Protocol of the Normal Canine Brain

    Science.gov (United States)

    Stadler, Krystina L.; Pease, Anthony P.; Ballegeer, Elizabeth A.

    2017-01-01

    Perfusion magnetic resonance imaging (MRI), specifically dynamic susceptibility MRI (DSC-MRI) is routinely performed as a supplement to conventional MRI in human medicine for patients with intracranial neoplasia and cerebrovascular events. There is minimal data on the use of DSC-MRI in veterinary patients and a DSC-MRI protocol in the veterinary patient has not been described. Sixteen normal dogs, 6 years or older were recruited for this study. The sample population included 11 large dogs (>11 kg) and 5 small dogs (11 kg, a useable AIF and perfusion map was generated. One dog less than 11 kg received the same contrast dose and rate. In this patient, the protocol did not generate a useable AIF. The remainder of the dogs less than 11 kg followed a protocol of 0.2 mmol/kg gadolinium-based contrast media at 1.5 ml/s with a 10 ml saline flush at 1.5 ml/s. A useable AIF and perfusion map was generated in the remaining dogs <11 kg using the higher contrast dose and slower rate protocol. This study establishes a contrast dose and administration rate for canine DSC-MRI imaging that is different in dogs greater than 11 kg compared to dogs less than 11 kg. These protocols may be used for future applications to evaluate hemodynamic disturbances in canine intracranial pathology.

  9. Magnetic resonance susceptibility weighted imaging in detecting intracranial calcification and hemorrhage

    Institute of Scientific and Technical Information of China (English)

    ZHU Wen-zhen; QI Jian-pin; ZHAN Chuan-jia; SHU Hong-ge; ZHANG Lin; WANG Cheng-yuan; XIA Li-ming; HU Jun-wu; FENG Ding-yi

    2008-01-01

    Background Computed tomography (CT) is better than routine magnetic resonance imaging (MRI) in detecting intracranial calcification. This study aimed to assess the value of MR susceptibility weighted imaging (SWI) in the detection and differentiation of intracranial calcification and hemorrhage.Methods Enrolled in this study were 35 patients including 13 cases of calcification demonstrated by CT and 22 cases of intracerebral hemorrhage. MR sequences used in all the subjects included axial T1WI, T2WI and SWI. The phase shift (PS) of calcification and hemorrhage on SWI was calculated and their signal features on corrected phase images were compared. The sensitivity of T1WI, T2WI and SWI in detecting intracranial calcification and hemorrhage was analyzed statistically.Results The detection rate of SWI for cranial calcification was 98.2%, significantly higher than that of T1 Wl and T2WI. It was not significantly different from that of CT (P >0.05). There were 49 hemorrhagic lesions at different stages detected n SWI, 30 on T2WI and 18 on T1WI. The average PS of calcification and hemorrhage was +0.734han routine MRI in detecting micro-hemorrhage, SWI may play an important role in differentiating cerebral diseases associated with calcification or hemorrhage.

  10. Correspondence between neutron depolarization and higher order magnetic susceptibility to investigate ferromagnetic clusters in phase separated systems.

    Science.gov (United States)

    Manna, Kaustuv; Samal, D; Bera, A K; Elizabeth, Suja; Yusuf, S M; Kumar, P S Anil

    2014-01-08

    It is a tough task to distinguish a short-range ferromagnetically correlated cluster-glass phase from a canonical spin-glass-like phase in many magnetic oxide systems using conventional magnetometry measurements. As a case study, we investigate the magnetic ground state of La0.85Sr0.15CoO3, which is often debated based on phase separation issues. We report the results of two samples of La0.85Sr0.15CoO3 (S-1 and S-2) prepared under different conditions. Neutron depolarization, higher harmonic ac susceptibility and magnetic relaxation studies were carried out along with conventional magnetometry measurements to differentiate subtle changes at the microscopic level. There is no evidence of ferromagnetic correlation in the sample S-2 attributed to a spin-glass phase, and this is compounded by the lack of existence of a second order component of higher harmonic ac susceptibility and neutron depolarization. A magnetic relaxation experiment at different temperatures complements the spin glass characteristic in S-2. All these signal a sharp variance when we consider the cluster-glass-like phase (phase separated) in S-1, especially when prepared from an improper chemical synthesis process. This shows that the nonlinear ac susceptibility is a viable tool to detect ferromagnetic clusters such as those the neutron depolarization study can reveal.

  11. Magnetic susceptibility measurements as proxy method to monitor soil pollution: the case study of S. Nicola di Melfi.

    Science.gov (United States)

    D'Emilio, Mariagrazia; Caggiano, Rosa; Coppola, Rosa; Macchiato, Maria; Ragosta, Maria

    2010-10-01

    The development of in situ, cheep, noninvasive, and fast strategies for soil monitoring is a crucial task for environmental research. In this paper, we present the results of three field surveys carried out in an industrial area of Southern Italy: S. Nicola di Melfi. The monitoring procedure is based on soil magnetic susceptibility measurements carried out by means of experimental protocols that our research group developed during the last years. This field surveys is supported by both geological characterization of the area and analytical determinations of metal concentrations in soils. Magnetic studies were carried out not only in situ but also in laboratory. Results show that, taking into account the influence due to the geomorphologic difference, soil magnetic susceptibility is an optimal indicator of the anthropogenic impact. So, our monitoring strategy discloses that the combined use of magnetic susceptibility measurements and soil geomorphology information may be used as a useful tool for the temporal monitoring of pollution evolution and for a fast screening of polluted zones.

  12. Solar Magnetic Flux Tube Simulations with Time-Dependent Ionization

    CERN Document Server

    Fawzy, Diaa E; Rammacher, Wolfgang

    2012-01-01

    In the present work we expand the study of time-dependent ionization previously identified to be of pivotal importance for acoustic waves in solar magnetic flux tube simulations. We focus on longitudinal tube waves (LTW) known to be an important heating agent of solar magnetic regions. Our models also consider new results of wave energy generation as well as an updated determination of the mixing length of convection now identified as 1.8 scale heights in the upper solar convective layers. We present 1-D wave simulations for the solar chromosphere by studying tubes of different spreading as function of height aimed at representing tubes in environments of different magnetic filling factors. Multi-level radiative transfer has been applied to correctly represent the total chromospheric emission function. The effects of time-dependent ionization are significant in all models studied. They are most pronounced behind strong shocks and in low density regions, i.e., the middle and high chromosphere. Concerning our m...

  13. Magnetic susceptibility to identify landscape segments on a detailed scale in the region of Jaboticabal, São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    Mariana dos Reis Barrios

    2012-08-01

    Full Text Available The agricultural potential is generally assessed and managed based on a one-dimensional vision of the soil profile, however, the increased appreciation of sustainable production has stimulated studies on faster and more accurate evaluation techniques and methods of the agricultural potential on detailed scales. The objective of this study was to investigate the possibility of using soil magnetic susceptibility for the identification of landscape segments on a detailed scale in the region of Jaboticabal, São Paulo State. The studied area has two slope curvatures: linear and concave, subdivided into three landscape segments: upper slope (US, concave, middle slope (MS, linear and lower slope (LS, linear. In each of these segments, 20 points were randomly sampled from a database with 207 samples forming a regular grid installed in each landscape segment. The soil physical and chemical properties, CO2 emissions (FCO2 and magnetic susceptibility (MS of the samples were evaluated represented by: magnetic susceptibility of air-dried fine earth (MS ADFE, magnetic susceptibility of the total sand fraction (MS TS and magnetic susceptibility of the clay fraction (MS Cl in the 0.00 - 0.15 m layer. The principal component analysis showed that MS is an important property that can be used to identify landscape segments, because the correlation of this property within the first principal component was high. The hierarchical cluster analysis method identified two groups based on the variables selected by principal component analysis; of the six selected variables, three were related to magnetic susceptibility. The landscape segments were differentiated similarly by the principal component analysis and by the cluster analysis using only the properties with higher discriminatory power. The cluster analysis of MS ADFE, MS TS and MS Cl allowed the formation of three groups that agree with the segment division established in the field. The grouping by cluster

  14. Susceptibility of CoFeB/AlOx/Co Magnetic Tunnel Junctions to Low-Frequency Alternating Current

    Directory of Open Access Journals (Sweden)

    Yuan-Tsung Chen

    2013-10-01

    Full Text Available This investigation studies CoFeB/AlOx/Co magnetic tunneling junction (MTJ in the magnetic field of a low-frequency alternating current, for various thicknesses of the barrier layer AlOx. The low-frequency alternate-current magnetic susceptibility (χac and phase angle (θ of the CoFeB/AlOx/Co MTJ are determined using an cac analyzer. The driving frequency ranges from 10 to 25,000 Hz. These multilayered MTJs are deposited on a silicon substrate using a DC and RF magnetron sputtering system. Barrier layer thicknesses are 22, 26, and 30 Å. The X-ray diffraction patterns (XRD include a main peak at 2θ = 44.7° from hexagonal close-packed (HCP Co with a highly (0002 textured structure, with AlOx and CoFeB as amorphous phases. The full width at half maximum (FWHM of the Co(0002 peak, decreases as the AlOx thickness increases; revealing that the Co layer becomes more crystalline with increasing thickness. χac result demonstrates that the optimal resonance frequency (fres that maximizes the χac value is 500 Hz. As the frequency increases to 1000 Hz, the susceptibility decreases rapidly. However, when the frequency increases over 1000 Hz, the susceptibility sharply declines, and almost closes to zero. The experimental results reveal that the mean optimal susceptibility is 1.87 at an AlOx barrier layer thickness of 30 Å because the Co(0002 texture induces magneto-anisotropy, which improves the indirect CoFeB and Co spin exchange-coupling strength and the χac value. The results concerning magnetism indicate that the magnetic characteristics are related to the crystallinity of Co.

  15. Model calculation of the static magnetic susceptibility in light rare earth metallic systems

    Science.gov (United States)

    Hammoud, Y.; Parlebas, J. C.

    1991-05-01

    Using the impurity Anderson model in the large N_f approximation, where N_f is the orbital and spin degeneracy of the f level, we calculate the zero temperature static paramagnetic susceptibility of light rare earth metallic systems. The calculation is performed for large values of the Coulomb U_ff electron-electron interactions with respect of the V hybridization of f1 and f2 configurations with the conduction states (i.e. f0 configuration) : we only keep the leading terms in a development in successive powers of 1/U_ff and V. Our numerical results on the magnetic susceptibility start from a simple analytic expression and are discussed in terms of the f level position, the hybridization V, the shape and filling of the conduction band and also the finite U_ff effects. Finally we present calculated curves for the susceptibility versus V in connection with the αγ transition of cerium and utilizing the same parameters as those used previously to obtain core level LIII absorption spectra : also in the case of the susceptibility, the hybridization appears to be an important parameter to describe the phase change from γ to α cerium. Nous utilisons le modèle d'Anderson à une impureté dans l'approximation des grands N_f où N_f est la dégénérescence d'orbitale et de spin du niveau f et nous calculons alors la susceptibilité paramagnétique statique (à température nulle) dans les systèmes métalliques de terres rares légères. Nous effectuons notre calcul pour des valeurs de l'interaction de Coulomb U_ff grandes par rapport à l'hybridation V des configurations f1 et f2 avec les états de conduction (c.-à-d. la configuration f0): nous ne retenons que les termes les plus imporatnts dans un développement en puissances successives de 1/U_ff et V. Ensuite nous discutons nos résultats numériques à partir d'une forme analytique simple obtenue pour la susceptibilité magnétique en fonction de la position du niveau f, de l'hybridation V, de la forme et du

  16. Magnetic susceptibility as a direct measure of oxidation state in LiFePO4 batteries and cyclic water gas shift reactors.

    Science.gov (United States)

    Kadyk, Thomas; Eikerling, Michael

    2015-08-14

    The possibility of correlating the magnetic susceptibility to the oxidation state of the porous active mass in a chemical or electrochemical reactor was analyzed. The magnetic permeability was calculated using a hierarchical model of the reactor. This model was applied to two practical examples: LiFePO4 batteries, in which the oxidation state corresponds with the state-of-charge, and cyclic water gas shift reactors, in which the oxidation state corresponds to the depletion of the catalyst. In LiFePO4 batteries phase separation of the lithiated and delithiated phases in the LiFePO4 particles in the positive electrode gives rise to a hysteresis effect, i.e. the magnetic permeability depends on the history of the electrode. During fast charge or discharge, non-uniform lithium distributionin the electrode decreases the hysteresis effect. However, the overall sensitivity of the magnetic response to the state-of-charge lies in the range of 0.03%, which makes practical measurement challenging. In cyclic water gas shift reactors, the sensitivity is 4 orders of magnitude higher and without phase separation, no hysteresis occurs. This shows that the method is suitable for such reactors, in which large changes of the magnetic permeability of the active material occurs.

  17. Magnetization and susceptibility of a parabolic InAs quantum dot with electron-electron and spin-orbit interactions in the presence of a magnetic field at finite temperature

    Science.gov (United States)

    Kumar, D. Sanjeev; Mukhopadhyay, Soma; Chatterjee, Ashok

    2016-11-01

    The magnetization and susceptibility of a two-electron parabolic quantum dot are studied in the presence of electron-electron and spin-orbit interactions as a function of magnetic field and temperature. The spin-orbit interactions are treated by a unitary transformation and an exactly soluble parabolic interaction model is considered to mimic the electron-electron interaction. The theory is finally applied to an InAs quantum dot. Magnetization and susceptibility are calculated using canonical ensemble approach. Our results show that Temperature has no effect on magnetization and susceptibility in the diamagnetic regime whereas electron-electron interaction reduces them. The temperature however reduces the height of the paramagnetic peak. The Rashba spin-orbit interaction is shown to shift the paramagnetic peak towards higher magnetic fields whereas the Dresselhaus spin-orbit interaction shifts it to the lower magnetic field side. Spin-orbit interaction has no effect on magnetization and susceptibility at larger temperatures.

  18. Cocaine dependent individuals with attenuated striatal activation during reinforcement learning are more susceptible to relapse.

    Science.gov (United States)

    Stewart, Jennifer L; Connolly, Colm G; May, April C; Tapert, Susan F; Wittmann, Marc; Paulus, Martin P

    2014-08-30

    Cocaine-dependent individuals show altered brain activation during decision making. It is unclear, however, whether these activation differences are related to relapse vulnerability. This study tested the hypothesis that brain-activation patterns during reinforcement learning are linked to relapse 1 year later in individuals entering treatment for cocaine dependence. Subjects performed a Paper-Scissors-Rock task during functional magnetic resonance imaging (fMRI). A year later, we examined whether subjects had remained abstinent (n=15) or relapsed (n=15). Although the groups did not differ on demographic characteristics, behavioral performance, or lifetime substance use, abstinent patients reported greater motivation to win than relapsed patients. The fMRI results indicated that compared with abstinent individuals, relapsed users exhibited lower activation in (1) bilateral inferior frontal gyrus and striatum during decision making more generally; and (2) bilateral middle frontal gyrus and anterior insula during reward contingency learning in particular. Moreover, whereas abstinent patients exhibited greater left middle frontal and striatal activation to wins than losses, relapsed users did not demonstrate modulation in these regions as a function of outcome valence. Thus, individuals at high risk for relapse relative to those who are able to abstain allocate fewer neural resources to action-outcome contingency formation and decision making, as well as having less motivation to win on a laboratory-based task.

  19. Susceptibility of pea, horse bean and bean to viruses in dependence on the age of the inoculated plants

    Directory of Open Access Journals (Sweden)

    Władysław Błaszczak

    2013-12-01

    Full Text Available Three cultivars of pea did not differ in their susceptibility to Cucumber Mosaic Virus (CMV notwithstanding the age of the inoculated plants. But their susceptibility to infection with Bean Yellow Mosaic Virus (BYMV differed. Horse bean cultivars 'Nadwiślański' and 'Major' proved to be less susceptible to Broad Bean True Mosaic Virus (BBTMV when older plants were-inoculated. Two bean cultivars 'Złota Saxa' and 'Earle' appeared to be susceptible to BBTMV only in the phase of developing primary leaves and the age-dependent resistance to infection increased faster in plants of the cv. 'Złota Saxa'. Both cultivars of bean showed also age-dependent resistance to infection by BYMV. All these viruses restricted growth and yield of plants. The decreases were greater when younger plants were inoculated. These dependences appeared most distinctly in pea cv. 'Sześciotygodniowy' infected with CMV and in two cultivars of bean infected with BYMV.

  20. Antiferromagnetism in the organic conductor bis-tetramethyltetraselenafulvalene hexafluoroarsenate [(TMTSF)2AsF6]: Static magnetic susceptibility

    DEFF Research Database (Denmark)

    Mortensen, Kell; Tomkiewicz, Yaffa; Bechgaard, Klaus

    1982-01-01

    temperature, evidence for magnetic crossover is observed. The experimental results show (TMTSF)2X, X- = AsF6- and PF6- to be members of a family with quite similar physical properties. The data are discussed on the basis of Overhauser's treatment of itinerant antiferromagnetism.......The anisotropy in the static magnetic susceptibility of bis-tetramethyltetraselenafulvalene hexafluoroarsenate [(TMTSF)2AsF6] has been investigated above and below the metal-to-insulator transition for a range of fields between 0.5 and 30 kG. The results are consistent with the expectations...

  1. Magnetic Susceptibility Signals to Reconstruct Lena River Freshwater Discharge Events in the Laptev Sea and Neelov Bay, Russian Arctic.

    Science.gov (United States)

    Rivera, J.; Williams, D. F.; Karabanov, E. B.; Kuzmin, M.; Buchinskyi, V.

    2004-12-01

    River discharge into the Arctic is known to cause changes in sea ice production and consecutively affect global climate. The Russian Lena River is one of the major contributors into the Arctic Ocean, delivering approximately 770 km3/year of freshwater and about 21 x106/year tons of suspended material. Here we present preliminary evidence of fresh water discharge events from the Lena River into the Laptev Sea, Russian Arctic. During two separate coring-oceanographic expeditions in July and September, 2003, over 25 piston, gravity and vibro cores were collected from Neelov Bay and along a transect that extends from the delta floodplain onto the Laptev shelf. Preliminary results from our cores demonstrate that high magnetic susceptibility signals are a good indicator of river sediments deposition and provide an estimate of the number and magnitude of the river discharge. Sedigraph analyses in combination with Wet Sieving analysis (grain size > 3phi) reveal changes in grain size distributions and accurate grain size compositions along the core, which are well correlated with high magnetic susceptibility peaks. Based on lithostratigraphic interpretations and magnetic susceptibility correlations, at least 6 major sections are identified as possible discharge events in two transects that extends from the Lena River Delta into the Laptev Sea Shelf. The magnitude of the magnetic susceptibility peaks appears to reflect the strength of flow and the resulting spatial distribution of sediments during each deposition event associated with each unit. In Neelov Bay, cores in Transect 2 show the possibility that terrestrial material may be from a different source than Bykovskaya channel in the south-east part of the bay. This terrestrial material may be transported from coastal sources by wave refraction or by wind, and/or submarine currents. Future work will help us to understand and reconstruct the chronology of observed sedimentological events.

  2. Relationship between chemical composition and magnetic susceptibility in the alkaline volcanics from the Isparta area, SW Turkey

    Indian Academy of Sciences (India)

    Ömer Elitok; Züheyr Kamacı; M Nuri Dolmaz; Kamil Yılmaz; Meltem Şener

    2010-12-01

    Potassium-rich volcanic rocks in the Isparta area (SW Turkey)consist mainly of older (Pliocene) volcanic rock suites (e.g., lamprophyre, basaltic trachyandesite, trachyandesite, trachyte) and younger (Quaternary) caldera forming lava dome/flows (e.g., tephriphonolite, trachyte) and pyroclastics (ash/pumice fall deposits and ignimbritic flows). The magnetic susceptibility () was performed for both groups. The magnetic susceptibility value of the less evolved rocks characterized by SiO2 > 57 wt%(e.g., basaltic trachyandesite, tephriphonolite, lamprophyric rocks) and having mostly mafic phenocrysts such as pyroxene, amphibole, and biotite-phlogopite is over 10 (10−3 [SI]). Fine to medium-grained and subhedral to anhedral opaque minerals are scattered especially in the matrix phase of the less evolved volcanic rocks. However, the value of the more evolved rocks (e.g., trachyte and trachyandesites) with SiO2 over 57 wt%vary between 0.1 and 28, but most of them below 10.SI values are negatively correlated with SiO2, Na2O, but positively correlated with Fe2O3, CaO, MnO, P2O5 and MgO contents, suggesting inverse variation of SI with fractionation of potassic magma. That is to say that less evolved volcanic rocks have relatively higher magnetic susceptibility values in the volcanic suite.Fine to medium-grained and subhedral to anhedral Fe-Ti oxides are scattered mainly in the matrix phase of the less evolved volcanics, presumably cause the pronounced relatively higher magnetic susceptibility.

  3. Magnetic susceptibility and Landau diamagnetism of a quantum collisional Plasmas with arbitrary degree of degeneration of electronic gas

    CERN Document Server

    Latyshev, A V

    2013-01-01

    The kinetic description of magnetic susceptibility and Landau diamagnetism of quantum collisional plasmas with any degeration of electronic gas is given. The correct expression of electric conductivity of quantum collisional plasmas with any degeration of electronic gas (see A. V. Latyshev and A. A. Yushkanov, Transverse electrical conductivity of a quantum collisional plasma in the Mermin approach. - Theor. and Math. Phys., V. 175(1):559-569 (2013)) is used.

  4. Shape Biased Low Power Spin Dependent Tunneling Magnetic Field Sensors

    Science.gov (United States)

    Tondra, Mark; Qian, Zhenghong; Wang, Dexin; Nordman, Cathy; Anderson, John

    2001-10-01

    Spin Dependent Tunneling (SDT) devices are leading candidates for inclusion in a number of Unattended Ground Sensor applications. Continued progress at NVE has pushed their performance to 1OOs of pT I rt. Hz 1 Hz. However, these sensors were designed to use an applied field from an on-chip coil to create an appropriate magnetic sensing configuration. The power required to generate this field (^100mW) is significantly greater than the power budget (^lmW) for a magnetic sensor in an Unattended Ground Sensor (UGS) application. Consequently, a new approach to creating an ideal sensing environment is required. One approach being used at NVE is "shape biasing." This means that the physical layout of the SDT sensing elements is such that the magnetization of the sensing film is correct even when no biasing field is applied. Sensors have been fabricated using this technique and show reasonable promise for UGS applications. Some performance trade-offs exist. The power is easily tinder 1 MW, but the sensitivity is typically lower by a factor of 10. This talk will discuss some of the design details of these sensors as well as their expected ultimate performance.

  5. The interplanetary magnetic field: radial and latitudinal dependences

    CERN Document Server

    Khabarova, Olga V

    2013-01-01

    Results of the analysis of spacecraft measurements at 1-5.4 AU are presented within the scope of the large-scale interplanetary magnetic field (IMF) structure investigation. The work is focused on revealing of the radial IMF component (Br) variations with heliocentric distance and latitude as seen by Ulysses. It was found out that |Br| decreases as ~r^-5/3 in the ecliptic plane vicinity (10 deg. of latitude). This is consistent with the previous results obtained on the basis of five spacecraft in-ecliptic measurements (Khabarova, Obridko, 2012). The difference between the experimentally found (r^-5/3) and commonly used (r^-2) radial dependence of Br may lead to mistakes in the IMF recalculations from point to point in the heliosphere. This can be one of the main sources of the 'magnetic flux excess' effect, which is exceeding of the distantly measured magnetic flux over the values obtained through the measurements at the Earth orbit. It is shown that the radial IMF component can be considered as independent o...

  6. Plasma Beta Dependence of Magnetic Compressibility in Solar Wind Turbulence

    Science.gov (United States)

    Chapman, S. C.; Hnat, B.; Kiyani, K. H.; Sahraoui, F.

    2014-12-01

    The turbulent signature of MHD scales in the near-Earth solar wind are known to be primarily incompressible which manifests itself in magnetic field fluctuation vector components to be aligned primarily perpendicular to the background magnetic field -- so-called "Variance Anisotropy". This, and other facts, have been seen as evidence for a majority Alfvenic turbulence cascade; with a small component (10%) of compressible fluctuations. When one approaches scales on the order of the ion-inertial length and the Larmor radius, this behaviour changes and it is now becoming increasingly evident that the spectral break at these scales is also accompanied by an increase in magnetic compressibility. This has been attributed to a phase change in the physics at these scales -- from fluid to kinetic -- and in particular to the dominant role of the Hall-effect at sub-ion scales. We will be presenting results from the Cluster mission to show how this increase in the compressibility is dependent on the ion plasma beta and what implications this has for the physics at sub-ion scales in the context of prominent theories and models for kinetic plasma turbulence.

  7. Detection of microcalcifications by characteristic magnetic susceptibility effects using MR phase image cross-correlation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Baheza, Richard A. [Department of Biomedical Engineering and Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee 37232-2310 (United States); Welch, E. Brian [Institute of Imaging Science and Departments of Radiology and Radiological Sciences and Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37232-2310 (United States); Gochberg, Daniel F. [Institute of Imaging Science and Departments of Radiology and Radiological Sciences, and Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37232-2310 (United States); Sanders, Melinda [Department of Pathology, Vanderbilt University, Nashville, Tennessee 37232-2310 (United States); Harvey, Sara [Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee 37232-2310 (United States); Gore, John C. [Institute of Imaging Science and Departments of Biomedical Engineering, Radiology and Radiological Sciences, Physics and Astronomy, and Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232-2310 (United States); Yankeelov, Thomas E., E-mail: thomas.yankeelov@vanderbilt.edu [Institute of Imaging Science and Departments of Radiology and Radiological Sciences, Biomedical Engineering, Physics and Astronomy, and Cancer Biology, Vanderbilt University, Nashville, Tennessee 37232-2310 (United States)

    2015-03-15

    Purpose: To develop and evaluate a new method for detecting calcium deposits using their characteristic magnetic susceptibility effects on magnetic resonance (MR) images at high fields and demonstrate its potential in practice for detecting breast microcalcifications. Methods: Characteristic dipole signatures of calcium deposits were detected in magnetic resonance phase images by computing the cross-correlation between the acquired data and a library of templates containing simulated phase patterns of spherical deposits. The influence of signal-to-noise ratio and various other MR parameters on the results were assessed using simulations and validated experimentally. The method was tested experimentally for detection of calcium fragments within gel phantoms and calcium-like inhomogeneities within chicken tissue at 7 T with optimized MR acquisition parameters. The method was also evaluated for detection of simulated microcalcifications, modeled from biopsy samples of malignant breast cancer, inserted in silico into breast magnetic resonance imaging (MRIs) of healthy subjects at 7 T. For both assessments of calcium fragments in phantoms and biopsy-based simulated microcalcifications in breast MRIs, receiver operator characteristic curve analyses were performed to determine the cross-correlation index cutoff, for achieving optimal sensitivity and specificity, and the area under the curve (AUC), for measuring the method’s performance. Results: The method detected calcium fragments with sizes of 0.14–0.79 mm, 1 mm calcium-like deposits, and simulated microcalcifications with sizes of 0.4–1.0 mm in images with voxel sizes between (0.2 mm){sup 3} and (0.6 mm){sup 3}. In images acquired at 7 T with voxel sizes of (0.2 mm){sup 3}–(0.4 mm){sup 3}, calcium fragments (size 0.3–0.4 mm) were detected with a sensitivity, specificity, and AUC of 78%–90%, 51%–68%, and 0.77%–0.88%, respectively. In images acquired with a human 7 T scanner, acquisition times below 12

  8. Task-evoked brain functional magnetic susceptibility mapping by independent component analysis (χICA).

    Science.gov (United States)

    Chen, Zikuan; Calhoun, Vince D

    2016-03-01

    Conventionally, independent component analysis (ICA) is performed on an fMRI magnitude dataset to analyze brain functional mapping (AICA). By solving the inverse problem of fMRI, we can reconstruct the brain magnetic susceptibility (χ) functional states. Upon the reconstructed χ dataspace, we propose an ICA-based brain functional χ mapping method (χICA) to extract task-evoked brain functional map. A complex division algorithm is applied to a timeseries of fMRI phase images to extract temporal phase changes (relative to an OFF-state snapshot). A computed inverse MRI (CIMRI) model is used to reconstruct a 4D brain χ response dataset. χICA is implemented by applying a spatial InfoMax ICA algorithm to the reconstructed 4D χ dataspace. With finger-tapping experiments on a 7T system, the χICA-extracted χ-depicted functional map is similar to the SPM-inferred functional χ map by a spatial correlation of 0.67 ± 0.05. In comparison, the AICA-extracted magnitude-depicted map is correlated with the SPM magnitude map by 0.81 ± 0.05. The understanding of the inferiority of χICA to AICA for task-evoked functional map is an ongoing research topic. For task-evoked brain functional mapping, we compare the data-driven ICA method with the task-correlated SPM method. In particular, we compare χICA with AICA for extracting task-correlated timecourses and functional maps. χICA can extract a χ-depicted task-evoked brain functional map from a reconstructed χ dataspace without the knowledge about brain hemodynamic responses. The χICA-extracted brain functional χ map reveals a bidirectional BOLD response pattern that is unavailable (or different) from AICA. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Relationship between chemical composition and magnetic susceptibility in sediment cores from Central Indian Ocean Basin

    Indian Academy of Sciences (India)

    J N Pattan; G Parthiban; V K Banakar; A Tomer; M Kulkarni

    2008-04-01

    Three sediment cores in a north–south transect (3°N to 13°S) from different sediment types of the Central Indian Ocean Basin (CIOB) are studied to understand the possible relationship between magnetic susceptibility () and Al, Fe, Ti and Mn concentrations. The calcareous ooze core exhibit lowest (12.32 × 10-7m3 kg−1), Al (2.84%), Fe (1.63%) and Ti (0.14%), terrigenous clay core with moderate (29.9 × 10-7 m3 kg−1) but highest Al (6.84%), Fe (5.20%) and Ti (0.44%), and siliceous ooze core with highest (38.06 × 10-7 m3 kg−1) but moderate Al (4.49%), Fe (2.80%) and Ti (0.19%) contents. The distribution of and detrital proxy elements (Al, Fe, and Ti) are identical in both calcareous and siliceous ooze. Interestingly, in terrigenous core, the behaviour of is identical to only Ti content but not with Al and Fe suggesting possibility of Al and Fe having a non-detrital source. The occurrence of phillipsite in terrigenous clay is evident by the Al-K scatter plot where trend line intersects K axis at more than 50% of total K suggesting excess K in the form of phillipsite. Therefore, the presence of phillipsite might be responsible for negative correlation between and Al ( = −0.52). In siliceous ooze the strong positive correlations among , Alexc and Feexc suggest the presence of authigenic Fe-rich smectite. High Mn content (0.5%) probably in the form of manganese micronodules is also contributing to in both calcareous and siliceous ooze but not in the terrigenous core where mean Mn content (0.1%) is similar to crustal abundance. Thus, systematically records the terrigenous variation in both the biogenic sediments but in terrigenous clay it indirectly suggests the presence of authigenic minerals.

  10. Doping evolution of the magnetic susceptibility and transport properties of Fe{sub 1+{delta}T}e{sub 1-x}Se{sub x} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y; Kremer, R K; Lin, C T [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany)

    2011-03-15

    A study of the doping evolution of the magnetic susceptibility and transport properties was performed on Fe{sub 1+{delta}T}e{sub 1-x}Se{sub x} (x = 0, 0.22, 0.32, 0.37 and 0.40) single crystals grown by the self-flux method. For x = 0, 0.22 and 0.32 the paramagnetic susceptibility {chi}(T) in the high-temperature regime can be well fitted with a modified Curie-Weiss law. The Curie-Weiss temperature {theta}{sub p} systematically decreases with increasing Se content, indicating the breakdown of the predominant antiferromagnetic (AFM) interactions originating from FeTe (x = 0). Bulk superconductivity is established for x = 0.37 and 0.40, while {chi}(T) monotonically increases with increasing temperature in the high-temperature regime, as widely observed in iron arsenides. The resistivity {rho}{sub ab} simultaneously changes from a semiconducting behavior for x = 0, 0.22, and 0.32 to metallic transport below 200 K for x = 0.37 and 0.40. A sudden drop of the Hall coefficient R{sub H} from positive to negative values signifies the AFM transition of the sample for x = 0 at T{sub N} = 68 K, as evidenced by the magnetic susceptibility measurements. For x = 0.22 and 0.32, R{sub H} is positive and monotonically increases with decreasing temperature. A dramatic change in R{sub H} is observed for x = 0.37 and 0.40, where the positive R{sub H} starts to decrease below T{sub N} = 68 K. A change of sign further occurs at 40 K for x = 0.40. The anomalous doping-dependent behavior for both magnetic susceptibility {chi}(T) and Hall coefficient R{sub H} can be interpreted with the scenario that the Fe{sub 1+{delta}T}e{sub 1-x}Se{sub x} system undergoes a critical transition from the ({pi}, 0) magnetic order of FeTe to the dominant ({pi}, {pi}) spin fluctuations of FeSe with the establishment of bulk superconductivity.

  11. Brain Phosphorus Magnetic Resonance Spectroscopy Imaging of Sleep Homeostasis and Restoration in Drug Dependence

    Directory of Open Access Journals (Sweden)

    George H. Trksak

    2007-01-01

    Full Text Available Numerous reports have documented a high occurrence of sleep difficulties in drug-dependent populations, prompting researchers to characterize sleep profiles and physiology in drug abusing populations. This mini-review examines studies indicating that drug-dependent populations exhibit alterations in sleep homeostatic and restoration processes in response to sleep deprivation. Sleep deprivation is a principal sleep research tool that results in marked physiological challenge, which provides a means to examine sleep homeostatic processes in response to extended wakefulness. A report from our laboratory demonstrated that following recovery sleep from sleep deprivation, brain high-energy phosphates particularly beta–nucleoside triphosphate (beta-NTP are markedly increased as measured with phosphorus magnetic resonance spectroscopy (MRS. A more recent study examined the effects of sleep deprivation in opiate-dependent methadone-maintained (MM subjects. The study demonstrated increases in brain beta-NTP following recovery sleep. Interestingly, these increases were of a markedly greater magnitude in MM subjects compared to control subjects. A similar study examined sleep deprivation in cocaine-dependent subjects demonstrating that cocaine-dependent subjects exhibit greater increases in brain beta-NTP following recovery sleep when compared to control subjects. The studies suggest that sleep deprivation in both MM subjects and cocaine-dependent subjects is characterized by greater changes in brain ATP levels than control subjects. Greater enhancements in brain ATP following recovery sleep may reflect a greater disruption to or impact of sleep deprivation in drug dependent subjects, whereby sleep restoration processes may be unable to properly regulate brain ATP and maintain brain high-energy equilibrium. These studies support the notion of a greater susceptibility to sleep loss in drug dependent populations. Additional sleep studies in drug abusing

  12. Composition dependent behavior in the ternary mixed magnetic insulator Co1-xMnyNix-yCl2·2H2O

    Science.gov (United States)

    DeFotis, G. C.; Hampton, A. S.; Wallin, T. J.; Trowell, K. T.; Pothen, J. M.; Welshhans, E. A.; Havas, K. C.

    2016-05-01

    The properties of ternary mixed magnetic Co1-xMnyNix-yCl2·2H2O are examined by dc magnetization and susceptibility measurements, from 1.8 to 300 K as a function of composition. This is only the second ternary magnetic insulator so studied. The three transition metal chloride dihydrate components are known to differ in the degree of spin anisotropy and in the distribution of ferromagnetic and antiferromagnetic exchange interactions within and between strongly coupled chemical and structural chains. The Curie and Weiss constants, in χM=C/(T-θ) fits to high temperature susceptibilities, are compared with weighted averages of pure component values. The observed Weiss constant is almost uniformly less negative than calculated. Maxima in low temperature susceptibilities vary widely in presence and location with composition. Some compositions exhibit no susceptibility maximum, many exhibit one maximum, and three exhibit two maxima. A T(x,y) diagram is constructed. Magnetization vs field isotherms exhibit different shapes as a function of composition, with hysteresis markedly composition dependent. For three mixtures hysteresis loops are studied as a function of temperature. An activation process model does not describe the temperature dependence well.

  13. Fluconazole Susceptibility in Cryptococcus gattii Is Dependent on the ABC Transporter Pdr11.

    Science.gov (United States)

    Yang, Mai Lee; Uhrig, John; Vu, Kiem; Singapuri, Anil; Dennis, Michael; Gelli, Angie; Thompson, George R

    2015-12-07

    Cryptococcus gattii isolates from the Pacific Northwest have exhibited higher fluconazole MICs than isolates from other sites. The mechanism of fluconazole resistance in C. gattii is unknown. We sought to determine the role of the efflux pumps Mdr1 and Pdr11 in fluconazole susceptibility. Using biolistic transformation of the parent isolate, we created a strain lacking Mdr1 (mdr1Δ) and another strain lacking Pdr11 (pdr11Δ). Phenotypic virulence factors were assessed by standard methods (capsule size, melanin production, growth at 30 and 37 °C). Survival was assessed in an intranasal murine model of cryptococcosis. Antifungal MICs were determined by the M27-A3 methodology. No differences in key virulence phenotypic components were identified. Fluconazole susceptibility was unchanged in the Mdr1 knockout or reconstituted isolates. However, fluconazole MICs decreased from 32 μg/ml for the wild-type isolate to fluconazole susceptibility in C. gattii. Genomic and expression differences between resistant and susceptible C. gattii clinical isolates should be assessed further in order to identify other potential mechanisms of resistance.

  14. Being in "Bad" Company: Power Dependence and Status in Adolescent Susceptibility to Peer Influence

    Science.gov (United States)

    Vargas, Robert

    2011-01-01

    Theories of susceptibility to peer influence have centered on the idea that lower status adolescents are likely to adopt the behaviors of high status adolescents. While status is important, social exchange theorists have shown the value of analyzing exchange relations between actors to understand differences in power. To build on status-based…

  15. The Latitudinal Gradient of Rainfall, Mineralogy, Albedo and Magnetic Susceptibility in West Africa

    Science.gov (United States)

    Williams, E. R.; Balsam, W.; Schaaf, C.; Yang, X.; Zhang, Q.; Ji, J.; Rossman, G.; Garimella, S.; Oldfield, F.; Lyons, J. R.; Ellwood, B.; Hartman, H.; Hicks, E.; Mansot, J. L.; Cesaire, T.; Thomas, P.

    2008-12-01

    In order to investigate the effect of climate on soil and surface sediment properties we examined four transects around the Sahara Desert. The transects were located in Mali, Niger, Benin, Togo, Egypt and Morocco and, with the exception of Egypt, each crossed a significant climatological rainfall gradient. The Egyptian transect was designed to characterize one of the driest portions of the Sahara Desert. Our study included laboratory measurements of mineralogy (XRD), elemental composition (XRF), grain size, optical reflectance (lab), magnetic susceptibility (MS)and remanences. In addition, albedo was determined from the MODIS satellite imagery from space. Many of our laboratory measurements exhibited variations with the rainfall gradient. Iron oxides (hematite and goethite), kaolinite, Al2O3, and TiO2 increased with increasing rainfall whereas SiO2, illite, and grain size decreased with increasing rainfall. Both laboratory-determined reflectivity and satellite-determine albedo decreased as rainfall increased. In part, this decrease in reflectivity/albedo with increasing rainfall appears to be the result of hematite, the dominant coloring agent for the soil in this region and the origin of the 'red' Sahel. The physical interpretation of these results centers on rainfall as a long-term leaching agent of surface material, and the control of physical properties by specific mineralogy. SiO2 is highly reflective and iron oxides are strongly absorptive in the visible range. The solubility of SiO2 in rainwater is orders of magnitude larger than all the iron oxides, with hematite the least soluble. It has long been recognized that leaching by rainfall produces dark red laterite in the near-surface oxidizing environment, a prominent geological feature throughout the high rainfall belt of West Africa. Laterite beds represent simultaneous enrichments of all iron oxides and a reduction in SiO2 by leaching. In the Sahara desert where rainfall is minimal (<10 mm/yr), SiO2 is

  16. Model for the orientation, magnetic field, and temperature dependence of the specific heat of CeCu6

    Science.gov (United States)

    Edelstein, A. S.

    1988-03-01

    The results of a model calculation of the orientation, magnetic field, and temperature dependence of the specific heat C of CeCu6 are found to be in good agreement with the single-crystal data of Amato et al. The model incorporates both the Kondo and crystal-field effects. It is suggested that the low-temperature Wilson's ratio C/Tχ, where χ is the susceptibility, may not change in an applied field H and that both C/T and χ at low temperatures as a function of H may be proportional to the many-body density of states at the energy μH.

  17. Evaluation of diamagnetic susceptibility effect on magnetic resonance phase images using gradient echo. On the partial volume effect in calcification

    Energy Technology Data Exchange (ETDEWEB)

    Sakuma, Toshiharu; Yamada, Naoaki; Yamada, Yukinori; Doi, Toyozo [National Cardiovascular Center, Suita, Osaka (Japan)

    1995-02-01

    To examine the ability of magnetic resonance imaging to visualize the diamagnetic susceptibility effects of calcification, phantom experiments using small lead balls in a dilute solution of copper chloride in water were carried out. Gradient echo phase images of the phantoms were obtained using varying imaging parameters (TR, TE, flip angle, slice thickness), and phase shift due to the lead balls was measured. Five choroid plexuses and three pineal glands with calcification were also examined using gradient echo phase images. As a result, it could be seen that the phase shift increased in proportion to both echo time and the ratio held by lead and calcification in a voxel (partial volume effect), and was independent of repetition time and flip angle. It could be confirmed that the gradient echo phase images are useful for detecting the diamagnetic susceptibility effects of calcification. (author).

  18. Magnetic Susceptibility in Surface Sediments in the Southern South China Sea and Its Implication for Sub-sea Methane Venting

    Institute of Scientific and Technical Information of China (English)

    Chen Zhong; Yan Wen; Tang Xianzan; Liu Jianguo; Chen Muhong; Yang Huaping

    2009-01-01

    In order to understand the characteristics of magnetic variability and their possible implication for sub-sea methane venting,magnetic susceptibility (MS) of 145 surface sediment samples from the southern South China Sea (SCS) was investigated.Magnetic particles extracted from 20 representative samples were also examined for their mineral,chemical compositions and micromorphology.Results indicate that MS values range between -7.73×10-8 and 45.06x10-8 m3/kg.The high MS zones occur at some hydrecarbon-bearing basins and along main tectonic zones,and low ones are distributed mainly within the river delta or along continental shelves.Iron concretions and manganese concretions are not main contributors for high MS values in sediments,while authigenic iron sulphide minerals are possibly responsible for the MS enhancement.This phenomenon is suspected to be produced by the reducing environment where the high upward venting methane beneath the seafloor reacts with seawater sulfate,resulting in seep precipitation of highly susceptible intermediate mineral pyrrhotite,greigite and paramagnetic pyrite.It suggests that MS variability is possibly one of the geochemical indicators for mapping sub-sea zones of methane venting in the southern SCS.

  19. Lithology and chronology of ice-sheet fluctuations (magnetic susceptibility of cores from the western Ross Sea)

    Science.gov (United States)

    Jennings, Anne E.

    1993-01-01

    The goals of the marine geology part of WAIS include reconstructing the chronology and areal extent of ice-sheet fluctuations and understanding the climatic and oceanographic influences on ice-sheet history. As an initial step toward attaining these goals, down-core volume magnetic susceptibility (MS) logs of piston cores from three N-S transects in the western Ross Sea are compared. The core transects are within separate petrographic provinces based on analyses of till composition. The provinces are thought to reflect the previous locations of ice streams on the shelf during the last glaciation. Magnetic susceptibility is a function of magnetic mineral composition, sediment texture, and sediment density. It is applied in the western Ross Sea for two purposes: (1) to determine whether MS data differentiates the three transects (i.e., flow lines), and thus can be used to make paleodrainage reconstructions of the late Wisconsinan ice sheet; and (2) to determine whether the MS data can aid in distinguishing basal till diamictons from diamictons of glacial-marine origin and thus, aid paleoenvironmental interpretations. A comparison of the combined data of cores in each transect is presented.

  20. Magnetic properties of high temperature superconductors. AC susceptibility and magnetostriction studies

    Energy Technology Data Exchange (ETDEWEB)

    Heill, L.K.

    1995-05-01

    The author of this thesis has measured the ac magnetic response function {mu} = {mu}`+i{mu}`` in melt-powder-melt-growth YBa{sub 2}Cu{sub 3}O{sub 7} (Y123) with insulating Y{sub 2}BaCuO{sub 5} (Y211) and in single crystal YBa{sub 2}Cu{sub 3}O{sub 7} (SC) in applied dc fields up to 8 T, oriented both parallel and perpendicular to the crystalline c-axis. Both samples are cubes with sides of about 1 mm. The response of the two samples was mapped out as a function of temperature, excitation field amplitude and frequency, dc field and field orientation. It is found that for both samples the loss peak line (LPL) and hence the irreversibility line (IL) exists at higher temperatures and fields for perpendicular field orientation than for parallel. Strong frequency but weak amplitude dependence is observed for parallel orientation, vice versa for perpendicular orientation. The measured response is strongly non-linear for perpendicular orientation, and intermediate between linear (ohmic) and extremely non-linear (Bean critical state) for parallel orientation. The situation at parallel orientation is close to but above the transition into a vortex solid state, and a power law temperature dependence with exponent 1.5 is obtained for the vortex glass transition line. For perpendicular orientation the response is consistent with that expected in a vortex solid. Pinning barriers are found by means of thermal activation analysis. Anomalous loss peaks {mu}``(T) are observed for the SC sample for intermediate fields in perpendicular orientation. Large magnetostriction is found in a flat single crystal Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} sample at low temperature and fields up to 6 T applied along the c-axis. 332 refs., 59 figs., 7 tabs.

  1. Association between Gc genotype and susceptibility to TB is dependent on vitamin D status.

    Science.gov (United States)

    Martineau, A R; Leandro, A C C S; Anderson, S T; Newton, S M; Wilkinson, K A; Nicol, M P; Pienaar, S M; Skolimowska, K H; Rocha, M A; Rolla, V C; Levin, M; Davidson, R N; Bremner, S A; Griffiths, C J; Eley, B S; Bonecini-Almeida, M G; Wilkinson, R J

    2010-05-01

    Group-specific component (Gc) variants of vitamin D binding protein differ in their affinity for vitamin D metabolites that modulate antimycobacterial immunity. We conducted studies to determine whether Gc genotype associates with susceptibility to tuberculosis (TB). The following subjects were recruited into case-control studies: in the UK, 123 adult TB patients and 140 controls, all of Gujarati Asian ethnic origin; in Brazil, 130 adult TB patients and 78 controls; and in South Africa, 281 children with TB and 182 controls. Gc genotypes were determined and their frequency was compared between cases versus controls. Serum 25-hydroxyvitamin D (25(OH)D) concentrations were obtained retrospectively for 139 Gujarati Asians, and case-control analysis was stratified by vitamin D status. Interferon (IFN)-gamma release assays were also performed on 36 Gujarati Asian TB contacts. The Gc2/2 genotype was strongly associated with susceptibility to active TB in Gujarati Asians, compared with Gc1/1 genotype (OR 2.81, 95% CI 1.19-6.66; p = 0.009). This association was preserved if serum 25(OH)D was or =20 nmol.L(-1) (p = 0.36). Carriage of the Gc2 allele was associated with increased PPD of tuberculin-stimulated IFN-gamma release in Gujarati Asian TB contacts (p = 0.02). No association between Gc genotype and susceptibility to TB was observed in other ethnic groups studied.

  2. Alloy and composition dependence of hydrogen embrittlement susceptibility in high-strength steel fasteners

    Science.gov (United States)

    Brahimi, S. V.; Yue, S.; Sriraman, K. R.

    2017-06-01

    High-strength steel fasteners characterized by tensile strengths above 1100 MPa are often used in critical applications where a failure can have catastrophic consequences. Preventing hydrogen embrittlement (HE) failure is a fundamental concern implicating the entire fastener supply chain. Research is typically conducted under idealized conditions that cannot be translated into know-how prescribed in fastener industry standards and practices. Additionally, inconsistencies and even contradictions in fastener industry standards have led to much confusion and many preventable or misdiagnosed fastener failures. HE susceptibility is a function of the material condition, which is comprehensively described by the metallurgical and mechanical properties. Material strength has a first-order effect on HE susceptibility, which increases significantly above 1200 MPa and is characterized by a ductile-brittle transition. For a given concentration of hydrogen and at equal strength, the critical strength above which the ductile-brittle transition begins can vary due to second-order effects of chemistry, tempering temperature and sub-microstructure. Additionally, non-homogeneity of the metallurgical structure resulting from poorly controlled heat treatment, impurities and non-metallic inclusions can increase HE susceptibility of steel in ways that are measurable but unpredictable. Below 1200 MPa, non-conforming quality is often the root cause of real-life failures. This article is part of the themed issue 'The challenges of hydrogen and metals'.

  3. Magnetic field dependence of the lowest-frequency edge-localized spin wave mode in a magnetic nanotriangle.

    Science.gov (United States)

    Lin, C S; Lim, H S; Wang, Z K; Ng, S C; Kuok, M H; Adeyeye, A O

    2011-03-01

    An understanding of the spin dynamics of nanoscale magnetic elements is important for their applications in magnetic sensing and storage. Inhomogeneity of the demagnetizing field in a non-ellipsoidal magnetic element results in localization of spin waves near the edge of the element. However, relative little work has been carried out to investigate the effect of the applied magnetic fields on the nature of such localized modes. In this study, micromagnetic simulations are performed on an equilateral triangular nanomagnet to investigate the magnetic field dependence of the mode profiles of the lowest-frequency spin wave. Our findings reveal that the lowest-frequency mode is localized at the base edge of the equilateral triangle. The characteristics of its mode profile change with the ground state magnetization configuration of the nanotriangle, which, in turn, depends on the magnitude of the in-plane applied magnetic field.

  4. Quantum Effects on an Atom with a Magnetic Quadrupole Moment in a Region with a Time-Dependent Magnetic Field

    Science.gov (United States)

    Fonseca, I. C.; Bakke, K.

    2017-01-01

    The quantum description of an atom with a magnetic quadrupole moment in the presence of a time-dependent magnetic field is analysed. It is shown that the time-dependent magnetic field induces an electric field that interacts with the magnetic quadrupole moment of the atom and gives rise to a Landau-type quantization. It is also shown that a time-independent Schrödinger equation can be obtained, i.e., without existing the interaction between the magnetic quadrupole moment of the atom and the time-dependent magnetic field, therefore, the Schrödinger equation can be solved exactly. It is also analysed this system subject to scalar potentials.

  5. Age-dependent susceptibilities of Bulinus truncatus snails to an aqueous extract of Pulicaria crispa (Forssk.) Oliv. (Asteraceae) leaves.

    Science.gov (United States)

    Ali, Elnour A; Bushara, Hamid O; Ali, Faisal S; Hussein, Mansour F

    2009-05-01

    This study was carried out to investigate the potential use of the herb Pulicaria crispa in the biological control of different developmental stages of Bulinus truncatus, a major snail intermediate host of urinary schistosomiasis. Age-dependent susceptibilities of mature adult snails, immature snails, juveniles, and one-day old egg masses to aqueous extracts of Pulicaria crispa leaves collected from Khartoum (Sudan) and Riyadh (Saudi Arabia) was determined and compared. The results show the juvenile snails are the most susceptible, followed in descending order by one-day old egg masses, immature snails, and mature adult snails. The P. crispa sample collected from Riyadh was significantly more potent against B. truncatus than that collected from Khartoum, as indicated by the least (LC50) and (LC90) values for all B. truncatus ages.

  6. Two novel CPs with double helical chains based rigid tripodal ligands: Syntheses, crystal structures, magnetic susceptibility and fluorescence properties

    Science.gov (United States)

    Wang, Xiao; Hou, Xiang-Yang; Zhai, Quan-Guo; Hu, Man-Cheng

    2016-11-01

    Two three-dimensional coordination polymers (CPs), namely [Cd(bpydb)- (H2bpydb)]n·0.5nH2O (1), and [Cu2(bpydb)2]n (2) (2,6-di-p-carboxyphenyl-4,4'- bipyridine1 = H2bpydb), containing a novel double-helical chains, which have been solvothermal synthesized, characterized, and structure determination. CPs 1-2 reveal the new (3,5)-net and (3,6)-net alb topology, respectively. The fluorescence properties of CPs 1-2 were investigated, and magnetic susceptibility measurements indicate that compound 1 has dominating antiferromagnetic couplings between metal ions.

  7. Magnetic Susceptibility and Geochemistry Records in the Yax-1 Borehole in the Chicxulub Impact Crater: A paleoclimatic approach in the K/Pg and P/E Boundaries.

    Science.gov (United States)

    Marca-Castillo, M.; Perez-Cruz, L. L.; Fucugauchi, J. U.; Buitrón Sánchez, B. E.

    2015-12-01

    Chicxulub impact crater is located in the northwestern sector of Yucatan Peninsula, Mexico. It is the best-preserved multi-ring impact crater on Earth. Several studies have been focused in this crater structure due its association with the Cretaceous/Paleogenous boundary events. The aim of this study is document the abrupt climate changes during the K/Pg and P/E boundaries based on the stratigraphy, magnetic properties (magnetic susceptibility) and geochemical (major elements) records in the Yaxcopoil-1 (Yax-1) borehole in the Chicxulub impact crater. The Yax 1 was drilled at 20° 44' 38.45'' N, 89° 43' 6.70'' W. Two intervals from 830 to 750 and between 750 and 700 m depth were selected for this study. Magnetic susceptibility logs and X-Ray Fluorescence (XRF) measures were taken every 10 cm using a Bartington magnetic susceptibility meter and a Thermo Scientific Niton XL3tGOLDD XRF analyzer. Results show variations in magnetic susceptibility logs and major elements (Ca, Si, Fe, Ti and Si) content in the K/Pg boundary at ca. 794 m depth. Magnetic susceptibility decrease abruptly, Ca values increase, and the other elements show low values. Geochemical results, manly the Ca-record, suggest that the P/E boundary might have happened around 745 m depth. These values are compared with 13C isotopes and they coincide with the Carbon Isotope Excursion (CIE), suggesting their relationship with the abrupt climate change and with the ocean acidification.

  8. Quantitative evaluation of susceptibility effects caused by dental materials in head magnetic resonance imaging

    Science.gov (United States)

    Strocchi, S.; Ghielmi, M.; Basilico, F.; Macchi, A.; Novario, R.; Ferretti, R.; Binaghi, E.

    2016-03-01

    This work quantitatively evaluates the effects induced by susceptibility characteristics of materials commonly used in dental practice on the quality of head MR images in a clinical 1.5T device. The proposed evaluation procedure measures the image artifacts induced by susceptibility in MR images by providing an index consistent with the global degradation as perceived by the experts. Susceptibility artifacts were evaluated in a near-clinical setup, using a phantom with susceptibility and geometric characteristics similar to that of a human head. We tested different dentist materials, called PAL Keramit, Ti6Al4V-ELI, Keramit NP, ILOR F, Zirconia and used different clinical MR acquisition sequences, such as "classical" SE and fast, gradient, and diffusion sequences. The evaluation is designed as a matching process between reference and artifacts affected images recording the same scene. The extent of the degradation induced by susceptibility is then measured in terms of similarity with the corresponding reference image. The matching process involves a multimodal registration task and the use an adequate similarity index psychophysically validated, based on correlation coefficient. The proposed analyses are integrated within a computer-supported procedure that interactively guides the users in the different phases of the evaluation method. 2-Dimensional and 3-dimensional indexes are used for each material and each acquisition sequence. From these, we drew a ranking of the materials, averaging the results obtained. Zirconia and ILOR F appear to be the best choice from the susceptibility artefacts point of view, followed, in order, by PAL Keramit, Ti6Al4V-ELI and Keramit NP.

  9. The curved Magallanes fold and thrust belt: Tectonic insights from a paleomagnetic and anisotropy of magnetic susceptibility study

    Science.gov (United States)

    Poblete, F.; Roperch, P.; Hervé, F.; Diraison, M.; Espinoza, M.; Arriagada, C.

    2014-12-01

    The Magallanes fold and thrust belt (FTB) presents a large-scale curvature from N-S oriented structures north of 52°S to nearly E-W in Tierra del Fuego Island. We present a paleomagnetic and anisotropy of magnetic susceptibility (AMS) study from 85 sites sampled in Cretaceous to Miocene marine sediments. Magnetic susceptibility is lower than 0.0005 SI for 76 sites and mainly controlled by paramagnetic minerals. AMS results indicate that the sedimentary fabric is preserved in the undeformed areas of Tierra del Fuego and the more external thrust sheets units, where an incipient lineation due to layer parallel shortening is recorded. Prolate AMS ellipsoids, indicating a significant tectonic imprint in the AMS fabric, are observed in the internal units of the belt. AMS results show a good correlation between the orientation of the magnetic lineation and the fold axes. However, in Península Brunswick, the AMS lineations are at ~20° counterclockwise to the strike of the fold axes. Pretectonic stable characteristic remanent magnetizations (ChRM) were determined in seven sites. A counterclockwise rotation (21.2° ± 9.2°) is documented by ChRM data from four sites near the hinge of the belt in Península Brunswick and near Canal Whiteside while there is no evidence of rotation near the nearly E-W oriented Vicuña thrust within Tierra del Fuego. The curved shape of the Cenozoic Magallanes FTB is not related to vertical axis rotation, and thus, the Magallanes FTB can be considered as a primary arc.

  10. Particle size dependence of the magnetic and magneto-caloric properties of HoCrO3

    Science.gov (United States)

    Yin, Shiqi; Sauyet, Theodore; Seehra, Mohindar S.; Jain, Menka

    2017-02-01

    Magnetic and magneto-caloric properties of polycrystalline powder samples of HoCrO3 with four different particle sizes are reported here. The samples were prepared by citrate method and were annealed at 700, 900, 1100, and 1300 °C to yield average particle sizes of 60 nm, 190 nm, 320 nm, and 425 nm, respectively, as determined by the analysis of X-ray diffraction patterns and images obtained by scanning electron microscopy. Additional structural characterization was done using Raman spectroscopy. Measurements of the magnetization of the samples were done from 5 K to 300 K in magnetic fields up to 70 kOe. Analysis of the temperature dependence of the paramagnetic susceptibility in terms of the modified Curie-Weiss law, including the Dzyaloshinsky-Moriya (DM) interaction, show small but systematic changes in the Néel temperature TNC r of Cr3+ ions, exchange constant J, and the DM interaction with variation in particle size. However, below TNC r the largest size-dependent effects are observed at 5 K, and the measured magnitudes of coercivity field HC are 1930, 2500, 4660, and 7790 Oe for the 60 nm, 190 nm, 320 nm, and 425 nm size particles, respectively, which can be interpreted by a single domain model. Enhancement of the particle size gives about a fourfold increase in the magnitude of the energy product, HC * MS, where MS is the saturation magnetization. However, as the particle size rises, an opposite trend is observed in the max magnetic entropy (ΔSM = 8.73, 7.22, 7.77, and 6.70 J/kg K) and the refrigerant capacity (RC = 388, 354, 330, and 310 J/kg) for the 60 nm, 190 nm, 320 nm, and 425 nm size particles, respectively. These results suggest ways to optimize the properties of HoCrO3 for applications in magnetic storage and magnetic refrigeration.

  11. Applying the anisotropy of magnetic susceptibility technique to the study of the tectonic evolution of the West Spitsbergen Fold-and-Thrust Belt

    OpenAIRE

    Dudzisz, Katarzyna; Szaniawski, Rafał; Michalski, Krzysztof; Manby, Geoffrey

    2016-01-01

    We demonstrate the use of the anisotropy of magnetic susceptibility (AMS) method to determine the orientation of the principal tectonic strain directions developed during the formation of the West Spitsbergen Fold-and-Thrust Belt (WSFTB). The AMS measurements and extensive rock-magnetic studies of the Lower Triassic rocks reported here were focused on the recognition of the magnetic fabric, the identification of ferromagnetic minerals and an estimation of the influence of ferro- and paramagne...

  12. Susceptibility of Caenorhabditis elegans to Burkholderia infection depends on prior diet and secreted bacterial attractants.

    Directory of Open Access Journals (Sweden)

    Vaughn S Cooper

    Full Text Available The nematode Caenorhabditis elegans may be killed by certain pathogenic bacteria and thus is a model organism for studying interactions between bacteria and animal hosts. However, growing nematodes on prey bacteria may influence their susceptibility to potential pathogens. A method of axenic nematode culture was developed to isolate and quantify interactions between C. elegans and potentially pathogenic strains of the Burkholderia cepacia complex. Studying these dynamics in liquid solution rather than on agar surfaces minimized nematode avoidance behavior and resolved more differences among isolates. Most isolates of B. cenocepacia, B. ambifaria and B. cepacia caused 60-80% mortality of nematodes after 7 days, whereas isolates of B. multivorans caused less mortality (<25% and supported nematode reproduction. However, some B. cenocepacia isolates recovered from chronic infections were much less virulent (5-28% mortality. As predicted, prior diet altered the outcome of interactions between nematodes and bacteria. When given the choice between Burkholderia and E. coli as prey on agar, axenically raised nematodes initially preferred most lethal Burkholderia isolates to E. coli as a food source, but this was not the case for nematodes fed E. coli, which avoided toxic Burkholderia. This food preference was associated with the cell-free supernatant and thus secreted compounds likely mediated bacterial-nematode interactions. This model, which isolates interactions between bacteria and nematodes from the effects of prior feeding, demonstrates that bacteria can influence nematode behavior and their susceptibility to pathogens.

  13. 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...

  14. Improving the method of low-temperature anisotropy of magnetic susceptibility (LT-AMS) measurements in air

    Science.gov (United States)

    Issachar, R.; Levi, T.; Lyakhovsky, V.; Marco, S.; Weinberger, R.

    2016-07-01

    This study examines the limitations of the method of low-temperature anisotropy of magnetic susceptibility (LT-AMS) measurements in air and presents technical improvements that significantly reduce the instrumental drift and measurement errors. We analyzed the temperature profile of porous chalk core after cooling in liquid nitrogen and found that the average temperature of the sample during the LT-AMS measurement in air is higher than 77K and close to 92K. This analysis indicates that the susceptibility of the paramagnetic minerals are amplified by a factor ˜3.2 relative to that of room temperature AMS (RT-AMS). In addition, it was found that liquid nitrogen was absorbed in the samples during immersing and contributed diamagnetic component of ˜-9 × 10-6 SI to the total mean susceptibility. We showed that silicone sheet placed around and at the bottom of the measuring coil is an effective thermal protection, preventing instrument drift by the cold sample. In this way, the measuring errors of LT-AMS reduced to the level of RT-AMS, allowing accurate comparison with standard AMS measurements. We examined the applicability of the LT-AMS measurements on chalk samples that consist weight) of paramagnetic minerals and showed that it helps to efficiently enhance the paramagnetic fabric. The present study offers a practical approach, which can be applied to various types of rocks to better delineate the paramagnetic phase using conventional equipment.

  15. Susceptibility of pRb-deficient epidermis to chemical skin carcinogenesis is dependent on the p107 allele dosage.

    Science.gov (United States)

    Santos, Mirentxu; Ruiz, Sergio; Lara, M Fernanda; Segrelles, Carmen; Moral, Marta; Martínez-Cruz, Ana Belén; Ballestín, Claudio; Lorz, Corina; García-Escudero, Ramón; Paramio, Jesús M

    2008-11-01

    Functional inactivation of the pRb-dependent pathway is a general feature of human cancer. However, only a reduced spectrum of tumors displays inactivation of the Rb gene. This can be attributed, at least partially, to the possible overlapping functions carried out by the related retinoblastoma family members p107 and p130. We observed that loss of pRb in epidermis, using the Cre/LoxP technology, results in proliferation and differentiation defects. These alterations are partially compensated by the elevation in the levels of p107. Moreover, epidermis lacking pRb and p107, but not pRb alone, develops spontaneous tumors, and double deficient primary keratinocytes are highly susceptible to Ha-ras-induced transformation. Two-stage chemical carcinogenesis experiments in mice lacking pRb in epidermis revealed a reduced susceptibility in papilloma formation and an increase in the malignant conversion. We have now explored whether the loss of one p107 allele, inducing a decrease in the levels of p107 up to normal levels could restore the susceptibility of pRb-deficient skin to two-stage protocol. We observed partial restoration in the incidence, number, and size of tumors. However, there is no increased malignancy despite sustained p53 activation. We also observed a partial reduction in the levels of proapoptotic proteins in benign papillomas. These data confirm our previous suggestions on the role of p107 as a tumor suppressor in epidermis in the absence of pRb.

  16. Photothermal investigation of local and depth dependent magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Pelzl, J; Meckenstock, R, E-mail: pelzl@fks.rub.d [Institute of Experimental Physics, Solid State Spectroscopy, Ruhr-University, D-44780 Bochum (Germany)

    2010-03-01

    To achieve a spatially resolved measurement of magnetic properties two different photothermal approaches are used which rely on heat dissipated by magnetic resonance absorption or thermal modulation of the magnetic properties, respectively. The heat produced by modulated microwave absorption is detected by the classical photothermal methods such as photoacoustic effect and mirage effect. Examples comprise depth resolution of the magnetization of layered tapes and visualisation of magnetic excitations in ferrites. The second photothermal technique relies on the local modulation of magnetic properties by a thermal wave generated with an intensity modulated laser beam incident on the sample. This technique has a higher spatial resolution and sensitivity and has been used to characterize lateral magnetic properties of multilayers and spintronic media. To extend the lateral resolution of the ferromagnetic resonance detection into the nm-range techniques have been developed which are based on the detection of the modulated thermal microwave response by the thermal probe of an atomic force microscope (AFM) or by detection the thermal expansion of the magnetic sample in the course of the resonant microwave absorption with an AFM or tunnelling microscope. These thermal near field based techniques in ferromagnetic resonance have been successfully applied to image magnetic inhomogeneities around nano-structures and to measure the ferromagnetic resonance from magnetic nano-dots.

  17. Density, porosity and magnetic susceptibility of the Ko\\v{s}ice meteorite shower and homogeneity of its parent meteoroid

    CERN Document Server

    Kohout, Tomáš; Tóth, Juraj; Husárik, Marek; Gritsevich, Maria; Britt, Daniel; Borovička, Jiří; Spurný, Pavel; Igaz, Antal; Svoreň, Ján; Kornoš, Leonard; Vereš, Peter; Koza, Július; Zigo, Pavol; Gajdoš, Štefan; Világi, Jozef; Čapek, David; Krišandová, Zuzana; Tomko, Dušan; Šilha, Jiří; Schunová, Eva; Bodnárová, Marcela; Búzová, Diana; Krejčová, Tereza

    2014-01-01

    Bulk and grain density, porosity, and magnetic susceptibility of 67 individuals of Ko\\v{s}ice H chondrite fall were measured. The mean bulk and grain densities were determined to be 3.43 g/cm$^\\text{3}$ with standard deviation (s.d.) of 0.11 g/cm$^\\text{3}$ and 3.79 g/cm$^\\text{3}$ with s.d. 0.07 g/cm$^\\text{3}$, respectively. Porosity is in the range from 4.2 to 16.1%. The logarithm of the apparent magnetic susceptibility (in 10$^\\text{-9}$ m$^\\text{3}$/kg) shows narrow distribution from 5.17 to 5.49 with mean value at 5.35 with s.d. 0.08. These results indicate that all studied Ko\\v{s}ice meteorites are of the same composition down to ~g scale without presence of foreign (non-H) clasts and are similar to other H chondrites. Ko\\v{s}ice is thus a homogeneous meteorite fall derived from a homogeneous meteoroid.

  18. Scale Dependence of Magnetic Helicity in the Solar Wind

    Science.gov (United States)

    Brandenburg, Axel; Subramanian, Kandaswamy; Balogh, Andre; Goldstein, Melvyn L.

    2011-01-01

    We determine the magnetic helicity, along with the magnetic energy, at high latitudes using data from the Ulysses mission. The data set spans the time period from 1993 to 1996. The basic assumption of the analysis is that the solar wind is homogeneous. Because the solar wind speed is high, we follow the approach first pioneered by Matthaeus et al. by which, under the assumption of spatial homogeneity, one can use Fourier transforms of the magnetic field time series to construct one-dimensional spectra of the magnetic energy and magnetic helicity under the assumption that the Taylor frozen-in-flow hypothesis is valid. That is a well-satisfied assumption for the data used in this study. The magnetic helicity derives from the skew-symmetric terms of the three-dimensional magnetic correlation tensor, while the symmetric terms of the tensor are used to determine the magnetic energy spectrum. Our results show a sign change of magnetic helicity at wavenumber k approximately equal to 2AU(sup -1) (or frequency nu approximately equal to 2 microHz) at distances below 2.8AU and at k approximately equal to 30AU(sup -1) (or nu approximately equal to 25 microHz) at larger distances. At small scales the magnetic helicity is positive at northern heliographic latitudes and negative at southern latitudes. The positive magnetic helicity at small scales is argued to be the result of turbulent diffusion reversing the sign relative to what is seen at small scales at the solar surface. Furthermore, the magnetic helicity declines toward solar minimum in 1996. The magnetic helicity flux integrated separately over one hemisphere amounts to about 10(sup 45) Mx(sup 2) cycle(sup -1) at large scales and to a three times lower value at smaller scales.

  19. Temperature and magnetization-dependent band-gap renormalization and optical many-body effects in diluted magnetic semiconductors

    OpenAIRE

    2005-01-01

    We calculate the Coulomb interaction induced density, temperature and magnetization dependent many-body band-gap renormalization in a typical diluted magnetic semiconductor GaMnAs in the optimally-doped metallic regime as a function of carrier density and temperature. We find a large (about 0.1 eV) band gap renormalization which is enhanced by the ferromagnetic transition. We also calculate the impurity scattering effect on the gap narrowing. We suggest that the temperature, magnetization, an...

  20. Origin of the magnetic susceptibility maximum in CaCu3Ru4O12 and electronic states in the A-site substituted compounds

    Science.gov (United States)

    Kao, Ting-Hui; Sakurai, Hiroya; Yu, Shan; Kato, Harukazu; Tsujii, Naohito; Yang, Hung-Duen

    2017-07-01

    CaCu3Ru4O12 shows a broad maximum at around 200 K in temperature dependence of magnetic susceptibility, whose origin is under debate. The present study addresses this problem, using high-quality samples of Ca1 -xAxCu3Ru4O12 (A = La, Na, and Sr) made by high-pressure synthesis technique. Unlike in a previous report, the maximum shifts to lower temperatures for the La substitution, becomes obscure by the Na substitution, and is less influenced by the Sr substitution. This behavior strongly suggests that the susceptibility maximum is caused by a sharp peak in the density of states just above the Fermi level, which induces strong spin fluctuations. Furthermore, the nature of electronic states of LaCu3Ru4O12 and NaCu3Ru4O12 are discussed; the former likely bears a Kondo character, and the latter has spin fluctuations of different origin below approximately 150 K.

  1. Simultaneous Quantitative MRI Mapping of T1, T2* and Magnetic Susceptibility with Multi-Echo MP2RAGE

    Science.gov (United States)

    Kober, Tobias; Möller, Harald E.; Schäfer, Andreas

    2017-01-01

    The knowledge of relaxation times is essential for understanding the biophysical mechanisms underlying contrast in magnetic resonance imaging. Quantitative experiments, while offering major advantages in terms of reproducibility, may benefit from simultaneous acquisitions. In this work, we demonstrate the possibility of simultaneously recording relaxation-time and susceptibility maps with a prototype Multi-Echo (ME) Magnetization-Prepared 2 RApid Gradient Echoes (MP2RAGE) sequence. T1 maps can be obtained using the MP2RAGE sequence, which is relatively insensitive to inhomogeneities of the radio-frequency transmit field, B1+. As an extension, multiple gradient echoes can be acquired in each of the MP2RAGE readout blocks, which permits the calculation of T2* and susceptibility maps. We used computer simulations to explore the effects of the parameters on the precision and accuracy of the mapping. In vivo parameter maps up to 0.6 mm nominal resolution were acquired at 7 T in 19 healthy volunteers. Voxel-by-voxel correlations and the test-retest reproducibility were used to assess the reliability of the results. When using optimized paramenters, T1 maps obtained with ME-MP2RAGE and standard MP2RAGE showed excellent agreement for the whole range of values found in brain tissues. Simultaneously obtained T2* and susceptibility maps were of comparable quality as Fast Low-Angle SHot (FLASH) results. The acquisition times were more favorable for the ME-MP2RAGE (≈ 19 min) sequence as opposed to the sum of MP2RAGE (≈ 12 min) and FLASH (≈ 10 min) acquisitions. Without relevant sacrifice in accuracy, precision or flexibility, the multi-echo version may yield advantages in terms of reduced acquisition time and intrinsic co-registration, provided that an appropriate optimization of the acquisition parameters is performed. PMID:28081157

  2. CoCrTa thin films for magnetic recording media: structure, magnetic properties and time-dependence effect

    NARCIS (Netherlands)

    Phan le kim, P.L.K.

    This thesis has been devoted to deposition process, structures, magnetic properties and time-dependence effect of CoCrTa magnetic thin films for recording media. The experimental study began from Chapter 5 by investigating properties of single layer CoCrTa thin films, produced under different

  3. Field-Dependent Magnetic Phase Transitions in Mixed-Valent TmSe

    DEFF Research Database (Denmark)

    Bjerrum Møller, Hans; Shapiro, S. M.; Birgenau, R. J.

    1977-01-01

    A neutron diffraction study of the field-dependent magnetic ordering in TmSe is reported. The magnetic strucutre in zero field is antiferromagnetic fcc type I with TN=3.2 K. The magnetic phase diagram may be understood as a successive domain reorientation and metamagnetic transitions for T...

  4. Dependence of the location of the Martian magnetic lobes on the interplanetary magnetic field direction

    Science.gov (United States)

    Romanelli, Norberto; Mazelle, Christian; Bertucci, Cesar; Gomez, Daniel

    2016-04-01

    The magnetic field topology surrounding the Martian atmosphere is mainly the result of gradients in the velocity of the solar wind (SW). Such variations in the SW velocity are in turn the result of a massloading process and forces associated with electric currents flowing around the ionosphere of Mars [Nagy et al 2004, Mazelle et al 2004, Brain et al 2015]. In particular, in the regions where the collisionless regime holds, the interplanetary magnetic field (IMF) frozen into the SW piles up in front of the stagnation region of the flow. At the same time, the magnetic field lines are stretched in the direction of the unperturbed SW as this stream moves away from Mars, giving rise to a magnetotail [Alfvén, 1957]. As a result and in contrast with an obstacle with and intrinsic global magnetic field, the structure and organization of the magnetic field around Mars depends on the direction of the IMF and its variabilities [Yeroshenko et al., 1990; Crider et al., 2004; Bertucci et al., 2003; Romanelli et al 2015]. In this study we use magnetometer data from the Mars Global Surveyor (MGS) spacecraft during portions of the premapping orbits of the mission to study the variability of the Martian-induced magnetotail as a function of the orientation of the IMF. The time spent by MGS in the magnetotail lobes during periods with positive solar wind flow-aligned IMF component B∥IMF suggests that their location as well as the position of the central polarity reversal layer (PRL) are displaced in the direction antiparallel to the IMF cross-flow component B⊥IMF . Analogously, in the cases where B∥IMF is negative, the lobes are displaced in the direction of B⊥IMF. We find this behavior to be compatible with a previously published B⊥IMF analytical model of the IMF draping, where for the first time, the displacement of a complementary reversal layer (denoted as IPRL for inverse polarity reversal layer) is deduced from first principles [Romanelli et al 2014]. We also

  5. Magnetic layer thickness dependence of all-optical magnetization switching in GdFeCo thin films

    Science.gov (United States)

    Yoshikawa, Hiroki; El Moussaoui, Souliman; Terashita, Shinnosuke; Ueda, Ryohei; Tsukamoto, Arata

    2016-07-01

    To clarify the relationship between all-optical magnetization switching (AOS) and nonlocal and nonadiabatic energy dissipation process, we focus on the contribution from energy dissipation in the depth direction. Differently designed structure dependence of created magnetic domain is observed from the reversal phenomenon, AOS, or multidomains by thermomagnetic nucleation (TMN) in GdFeCo multilayer thin films. TMN depends on the shared absorbed energy throughout the continuous metallic volume. On the other hand, AOS critically depends on nonadiabatic energy dissipation process with the electron system in sub-picoseconds. Furthermore, the laser fluence dependence of AOS-created domain sizes indicates that the value of irradiated laser fluence threshold per magnetic domain volume is almost constant. However, a lower laser irradiation fluence below 1-2 mW has a larger value and thickness dependence. From these results, we suggest that AOS depends on energy dissipation from the incident surface in the depth direction for a few picoseconds.

  6. Calculation of static and dynamic linear magnetic response in approximate time-dependent density functional theory.

    Science.gov (United States)

    Krykunov, Mykhaylo; Autschbach, Jochen

    2007-01-14

    We report implementations and results of time-dependent density functional calculations (i) of the frequency-dependent magnetic dipole-magnetic dipole polarizability, (ii) of the (observable) translationally invariant linear magnetic response, and (iii) of a linear intensity differential (LID) which includes the dynamic dipole magnetizability. The density functional calculations utilized density fitting. For achieving gauge-origin independence we have employed time-periodic magnetic-field-dependent basis functions as well as the dipole velocity gauge, and have included explicit density-fit related derivatives of the Coulomb potential. We present the results of calculations of static and dynamic magnetic dipole-magnetic dipole polarizabilities for a set of small molecules, the LID for the SF6 molecule, and dispersion curves for M-hexahelicene of the origin invariant linear magnetic response as well as of three dynamic polarizabilities: magnetic dipole-magnetic dipole, electric dipole-electric dipole, and electric dipole-magnetic dipole. We have also performed comparison of the linear magnetic response and magnetic dipole-magnetic dipole polarizability over a wide range of frequencies for H2O and SF6.

  7. Magnetic susceptibility of Alq{sub 3} powder, pure and Al-doped 8-hydroxyquinoline

    Energy Technology Data Exchange (ETDEWEB)

    Burke, Franklyn, E-mail: frburke@tcd.i [School of Physics and CRANN, Trinity College, Dublin 2 (Ireland); Abid, Mohamed; Stamenov, Plamen; Coey, J.M.D. [School of Physics and CRANN, Trinity College, Dublin 2 (Ireland)

    2010-05-15

    Single-crystal nanowires several microns long and 100-200 nm in diameter were grown by physical vapour deposition from mixed Alq{sub 3}/gamma-Al{sub 2}O{sub 3} powder. The crystals are orthorhombic Al-doped 8-hydroxyquinoline. The molar susceptibility is -3x10{sup -9} at room temperature, and it shows a Curie-law upturn below about 50 K. The approach to saturation at low temperature indicates a density of S=1/2 defects 4x10{sup -4} per formula unit. Pure 8-hydroxyquinoline and aluminium (Alq{sub 3}) behave similarly. Pressed pellets exhibit much increased paramagnetic susceptibility due to iron ions scavanged from the steel die. Subsequent melting of these samples produces a ferromagnetic signal of order 0.01 A m{sup 2} kg{sup -1}, which is attributed to metallic iron nanoclusters in the organic material.

  8. Magnetization at the interface of Cr2O3 and paramagnets with large stoner susceptibility

    Science.gov (United States)

    Cao, Shi; Street, M.; Wang, Junlei; Wang, Jian; Zhang, Xiaozhe; Binek, Ch; Dowben, P. A.

    2017-03-01

    From the Cr 2p3/2 x-ray magnetic circular dichroism signal, there is clear evidence of interface polarization with overlayers of both Pd and Pt on chromia (Cr2O3). The residual boundary polarization of chomia is stronger for a Pt overlayer than in the case of a Pd overlayer. The reduction of chromia boundary magnetization with a paramagnetic metal overlayer, compared to the free surface, is interpreted as a response to the induced spin polarization in Pt and Pd. Magnetization induced in a Pt overlayer, via proximity to the chromia boundary magnetization, is evident in the polar magneto-optical Kerr measurements. These results are essential to explainations why Pt and Pd are excellent spacer layers for voltage controlled exchange bias, in the [Pd/Co] n /Pd/Cr2O3 and [Pt/Co] n /Pt/Cr2O3 perpendicular magneto-electric exchange bias systems. The findings pave the way to realize ultra-fast reversal of induced magnetization in a free moment paramagnetic layer, with possible application in voltage-controlled magnetic random access memory.

  9. Magnetization at the interface of Cr2O3 and paramagnets with large stoner susceptibility.

    Science.gov (United States)

    Cao, Shi; Street, M; Wang, Junlei; Wang, Jian; Zhang, Xiaozhe; Binek, Ch; Dowben, P A

    2017-03-15

    From the Cr 2p3/2 x-ray magnetic circular dichroism signal, there is clear evidence of interface polarization with overlayers of both Pd and Pt on chromia (Cr2O3). The residual boundary polarization of chomia is stronger for a Pt overlayer than in the case of a Pd overlayer. The reduction of chromia boundary magnetization with a paramagnetic metal overlayer, compared to the free surface, is interpreted as a response to the induced spin polarization in Pt and Pd. Magnetization induced in a Pt overlayer, via proximity to the chromia boundary magnetization, is evident in the polar magneto-optical Kerr measurements. These results are essential to explainations why Pt and Pd are excellent spacer layers for voltage controlled exchange bias, in the [Pd/Co] n /Pd/Cr2O3 and [Pt/Co] n /Pt/Cr2O3 perpendicular magneto-electric exchange bias systems. The findings pave the way to realize ultra-fast reversal of induced magnetization in a free moment paramagnetic layer, with possible application in voltage-controlled magnetic random access memory.

  10. MR imaging differentiation of Fe(2+) and Fe(3+) based on relaxation and magnetic susceptibility properties.

    Science.gov (United States)

    Dietrich, Olaf; Levin, Johannes; Ahmadi, Seyed-Ahmad; Plate, Annika; Reiser, Maximilian F; Bötzel, Kai; Giese, Armin; Ertl-Wagner, Birgit

    2017-04-01

    The aim of this study is to evaluate the MR imaging behavior of ferrous (Fe(2+)) and ferric (Fe(3+)) iron ions in order to develop a noninvasive technique to quantitatively differentiate between both forms of iron. MRI was performed at 3 T in a phantom consisting of 21 samples with different concentrations of ferrous and ferric chloride solutions (between 0 and 10 mmol/L). A multi-echo spoiled gradient-echo pulse sequence with eight echoes was used for both T 2* and quantitative susceptibility measurements. The transverse relaxation rate, R 2* = 1/T 2*, was determined by nonlinear exponential fitting based on the mean signals in each sample. The susceptibilities, χ, of the samples were calculated after phase unwrapping and background field removal by fitting the spatial convolution of a unit dipole response to the measured internal field map. Relaxation rate changes, ΔR 2*(c Fe), and susceptibility changes, Δχ(c Fe), their linear slopes, as well as the ratios ΔR 2*(c Fe) / Δχ(c Fe) were determined for all concentrations. The linear slopes of the relaxation rate were (12.5 ± 0.4) s(-1)/(mmol/L) for Fe(3+) and (0.77 ± 0.09) s(-1)/(mmol/L) for Fe(2+) (significantly different, z test P relaxation behaviors in MRI but similar susceptibility patterns. These properties can be used to differentiate ferrous and ferric samples.

  11. Consistent behaviour of AC susceptibility and transport properties in magnetic superconductor RuSr 2GdCu 2O 8

    Science.gov (United States)

    Očko, M.; Živkovic, I.; Prester, M.; Drobac, Dj.; Ariosa, D.; Berger, H.; Pavuna, D.

    2004-02-01

    We report on AC susceptibility, resistivity, thermopower and measurements of sintered magnetic superconductor RuSr 2GdCu 2O 8. The antiferromagnetic phase transition at 133 K is seen clearly in the AC susceptibility as well as in the derivative of resistivity and thermopower. Above the antiferromagnetic transition, we have found some new evidences of the similarity between HTC compounds and the magnetic superconductor. The onset of superconductivity is observed by both transport methods at 46 K, and an explanation why it is not seen in the AC susceptibility data is given. The end of the SC transition occurs at about 24 K in all measured properties. We discuss the steps of broad SC transition, especially the maximum in susceptibility at 34 K, and compare our results with related studies reported in the literature.

  12. Consistent behaviour of AC susceptibility and transport properties in magnetic superconductor RuSr{sub 2}GdCu{sub 2}O{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Ocko, M. E-mail: ocko@ifs.hr; Zivkovic, I.; Prester, M.; Drobac, Dj.; Ariosa, D.; Berger, H.; Pavuna, D

    2004-02-01

    We report on AC susceptibility, resistivity, thermopower and measurements of sintered magnetic superconductor RuSr{sub 2}GdCu{sub 2}O{sub 8}. The antiferromagnetic phase transition at 133 K is seen clearly in the AC susceptibility as well as in the derivative of resistivity and thermopower. Above the antiferromagnetic transition, we have found some new evidences of the similarity between HTC compounds and the magnetic superconductor. The onset of superconductivity is observed by both transport methods at 46 K, and an explanation why it is not seen in the AC susceptibility data is given. The end of the SC transition occurs at about 24 K in all measured properties. We discuss the steps of broad SC transition, especially the maximum in susceptibility at 34 K, and compare our results with related studies reported in the literature.

  13. Padé approximations for the magnetic susceptibilities of Heisenberg antiferromagnetic spin chains for various spin values.

    Science.gov (United States)

    Law, J M; Benner, H; Kremer, R K

    2013-02-13

    The temperature dependence of the spin susceptibilities of S = 1, 3/2, 2, 5/2 and 7/2 Heisenberg antiferromagnetic 1D spins chains with nearest-neighbor coupling was simulated via quantum Monte Carlo calculations, within the reduced temperature range of 0.005 ≤ T* ≤ 100, and fitted to a Padé approximation with deviations between the simulated and fitted data of the same order of magnitude as or smaller than the quantum Monte Carlo simulation error. To demonstrate the practicality of our theoretical findings, we compare these results with the susceptibility of the well known 1D chain compound TMMC ([(CH(3))(4)N[MnCl(3)

  14. Applying the anisotropy of magnetic susceptibility technique to the study of the tectonic evolution of the West Spitsbergen Fold-and-Thrust Belt

    Directory of Open Access Journals (Sweden)

    Katarzyna Dudzisz

    2016-12-01

    Full Text Available We demonstrate the use of the anisotropy of magnetic susceptibility (AMS method to determine the orientation of the principal tectonic strain directions developed during the formation of the West Spitsbergen Fold-and-Thrust Belt (WSFTB. The AMS measurements and extensive rock-magnetic studies of the Lower Triassic rocks reported here were focused on the recognition of the magnetic fabric, the identification of ferromagnetic minerals and an estimation of the influence of ferro- and paramagnetic minerals on magnetic susceptibility. At most sites, the paramagnetic minerals controlled the magnetic susceptibility, and at only one site the impact of ferromagnetic minerals was higher. The AMS technique documented the presence of different types of magnetic fabrics within the sampled sites. At two sites, a normal (Kmin perpendicular to the bedding magnetic fabric of sedimentary origin was detected. This was associated with a good clustering of the maximum AMS axes imposed by tectonic strain. The Kmax magnetic lineation directions obtained here parallel the general NNW–SSE trend of the WSFTB fold axial traces and thrust fronts. The two other investigated sites possessed mixed and inverted fabrics, the latter of which appear to reflect the presence of iron-bearing carbonates.

  15. Magnetic field-dependent shape anisotropy in small patterned films studied using rotating magnetoresistance

    OpenAIRE

    Xiaolong Fan; Hengan Zhou; Jinwei Rao; Xiaobing Zhao; Jing Zhao; Fengzhen Zhang; Desheng Xue

    2015-01-01

    Based on the electric rotating magnetoresistance method, the shape anisotropy of a Co microstrip has been systematically investigated. We find that the shape anisotropy is dependent not only on the shape itself, but also on the magnetization distribution controlled by an applied magnetic field. Together with micro-magnetic simulations, we present a visualized picture of how non-uniform magnetization affects the values and polarities of the anisotropy constants and . From the perspective of po...

  16. Shape Dependence of Low-Temperature Magnetic Relaxation of Mn12Ac

    Institute of Scientific and Technical Information of China (English)

    LIU Hai-Qing; SU Shao-Kui; JING Xiu-nian; LIU Ying; LI Yan-rong; HE Lun-Hua; GE Pei-Wen; YAN Qi-Wei; WANG Yun-Ping

    2008-01-01

    We report the discovery that the low-temperature magnetic relaxation in Mn,12 Ac single crystals strongly depends on the shape of the samples. The relaxation time exhibits a minimum at the phase transition point between ferromagnetic and antiferromagnetic phases. The shape dependence is attributed to the dipolar interaction between molecular magnets.

  17. THE PRODUCTIVITY OF SUGAR BEET MONOGERM LINES DEPENDING ON CERCOSPORA (Cercospora beticola Sacc. SUSCEPTIBILITY

    Directory of Open Access Journals (Sweden)

    Andrija Kristek

    2003-06-01

    Full Text Available The producing values of monogerm CMS lines of sugar beet and their tolerance on cercospora leaf spot are investigated in Osijek during two years (2001, 2002 under the following conditions: natural infection and full protection with fungicides. The parameters for evaluation were root quality and yield, just as visual review of leaf damages. Twenty eight genetically divergent CMS lines and two standards were confirmed by the examinations. The test results indicate achieved progress in breeding and monogerm CMS lines value which can be used for obtaining new hybrids and further improvements. Three investigated lines achieved high root yield on the level of standards and even ten lines had the same or higher digestion than better standard. It was found out that in the case of fungicide apply, root yield increased on the average by 7.09 t/ha (16%, sugar content by 0.81% (rel. 5% and sugar yield by 1.38 t/ha (22.8%. Protection measures with fungicides had higher influence on production results of line being susceptible to cercospora and compared to cercospora tolerant lines.

  18. Single-crystal growth, crystallography, magnetic susceptibility, heat capacity, and thermal expansion of the antiferromagnetic S=1 chain compound CaV[subscript 2]O[subscript 4

    Energy Technology Data Exchange (ETDEWEB)

    Niazi, A.; Bud' ko, S.L.; Schlagel, D.L.; Yan, J.Q.; Lograsso, T.A.; Kreyssig, A.; Das, S.; Nandi, S.; Goldman, A.I.; Honecker, A.; McCallum, R.W.; Reehuis, M.; Pieper, O.; Lake, B.; Johnston, D.C.; (Ames; Gö); (tingen); (HMI); (MXPL-F)

    2009-05-01

    The compound CaV{sub 2}O{sub 4} contains V{sup +3} cations with spin S=1 and has an orthorhombic structure at room temperature containing zigzag chains of V atoms running along the c axis. We have grown single crystals of CaV{sub 2}O{sub 4} and report crystallography, static magnetization, magnetic susceptibility x, ac magnetic susceptibility, heat capacity C{sub p}, and thermal expansion measurements in the temperature T range of 1.8--350 K on the single crystals and on polycrystalline samples. An orthorhombic-to-monoclinic structural distortion and a long-range antiferromagnetic (AF) transition were found at sample-dependent temperatures T{sub S}{approx}108--145 K and T{sub N}{approx}51--76 K, respectively. In two annealed single crystals, another transition was found at {approx}200 K. In one of the crystals, this transition is mostly due to V{sub 2}O{sub 3} impurity phase that grows coherently in the crystals during annealing. However, in the other crystal the origin of this transition at 200 K is unknown. The x(T) shows a broad maximum at {approx}300 K associated with short-range AF ordering and the anisotropy of x above T{sub N} is small. The anisotropic x(T{yields}0) data below T{sub N} show that the (average) easy axis of the AF magnetic structure is the b axis. The C{sub p}(T) data indicate strong short-range AF ordering above T{sub N}, consistent with the x(T) data. We fitted our x data by a J{sub 1}-J{sub 2} S=1 Heisenberg chain model, where J{sub 1}(J{sub 2}) is the (next)-nearest-neighbor exchange interaction. We find J{sub 1}{approx}230 K and surprisingly, J{sub 2}/J{sub 1}{approx}0 (or J{sub 1}/J{sub 2}{approx}0). The interaction J{sub {perpendicular}} between these S=1 chains leading to long-range AF ordering at T{sub N} is estimated to be J{sub {perpendicular}}/J{sub 1}{approx_equal}0.04.

  19. In vivo screening of hepatocellular carcinoma using AC susceptibility of anti-alpha fetoprotein-activated magnetic nanoparticles.

    Directory of Open Access Journals (Sweden)

    Jen-Jie Chieh

    Full Text Available With antibody-mediated magnetic nanoparticles (MNPs applied in cancer examinations, patients must pay at least twice for MNP reagents in immunomagnetic reduction (IMR of in vitro screening and magnetic resonance imaging (MRI of in vivo tests. This is because the high maintenance costs and complex analysis of MRI have limited the possibility of in vivo screening. Therefore, this study proposes novel methods for in vivo screening of tumors by examining the AC susceptibility of bound MNPs using scanning superconducting-quantum-interference-device (SQUID biosusceptometry (SSB, thereby demonstrating high portability and improved economy. The favorable agreement between in vivo tests using SSB and MRI demonstrated the feasibility of in vivo screening using SSB for hepatocellular carcinoma (HCC targeted by anti-alpha fetoprotein (AFP-mediated MNPs. The magnetic labeling was also proved by in vitro tests using SSB and biopsy assays. Therefore, patients receiving bioprobe-mediated MNPs only once can undergo in vivo screening using SSB in the future.

  20. Paleomagnetic and Anisotropy of Magnetic Susceptibility (AMS analyses of the Plio-Pleistocene extensional Todi basin, Central Italy

    Directory of Open Access Journals (Sweden)

    L. Alfonsi

    1997-06-01

    Full Text Available In the last few years paleomagnetic investigations within the Apennine chain have revealed that the area is characterized by a complex pattern of deformation, not linkable to a simple and homogeneous process. In order to estimate the amount, sense and timing of vertical axis rotations within the Central Apennines, Neogene continental basins have been investigated for paleomagnetic studies. The paleomagnetic results obtained in the Plio-Pleistocene Todi basin showed that the Upper Pliocene-Lower Pleistocene evolution, associated with major dip-slip tectonics, has not involved vertical axis rotation since that time. The Anisotropy of Magnetic Susceptibility analysis (AMS, carried out on the same samples treated for paleomagnetic determination, revealed the presence of two groups of specimens characterized by different magnetic lineation directions. One direction trends NE-SW and is parallel to the orientation of the regional extension stress typical of the area. This direction is observed throughout the northern basin. The other, restricted to the southern basin, trends N-S and shows no links with the tectonic, hydrological-sedimentary conditions of the area. The results of the AMS analysis will be presented and discussed in the light of the rock magnetic results and the tectonic framework of the area.

  1. Magnetic susceptibility study of Ce{sup 3+} in PbCeA (A=Te, Se, S)

    Energy Technology Data Exchange (ETDEWEB)

    Gratens, X., E-mail: xgratens@gmail.com [Instituto de Fisica, Universidade de Sao Paulo, 05315-970, Sao Paulo (Brazil); Isber, S., E-mail: si00@aub.edu.lb [American University of Beirut, Department of Physics, Bliss Street, PO Box 11-0236, Beirut 1107-2020 (Lebanon); Charar, S., E-mail: salam.charar@iut-nimes.fr [Group d' Etudes des Semiconducteurs (GES), Universite Montpellier II, CC074, 34095 Montpellier Cedex 5 (France); Golacki, Z. [Institute of Physics, Polish Academy of Sciences, Pl.02-668 Warsaw (Poland)

    2012-09-15

    The magnetic susceptibility of Pb{sub 1-x}Ce{sub x}A (A=S, Se and Te) crystals with Ce{sup 3+} concentrations 0.006{<=}x{<=}0.036 was investigated in the temperature range from 2 K to 300 K. The magnetic susceptibility data was found to be consistent with a {sup 2}F{sub 5/2} lowest manifold for Ce{sup 3+} ions with a crystal-field splitting {Delta}=E({Gamma}{sub 8})-E({Gamma}{sub 7}) of about 340 K, 440 K and 540 K for Pb{sub 1-x}Ce{sub x}Te, Pb{sub 1-x}Ce{sub x}Se, and Pb{sub 1-x}Ce{sub x}S, respectively. For all the three compounds the doublet {Gamma}{sub 7} lies below the {Gamma}{sub 8} quadruplet which confirms the substitution of Pb{sup 2+} by Ce{sup 3+} ions in the host crystals. The observed values for the crystal-field splitting are in good agreement with the calculated ones based on the point-charge model. Moreover, the effective Lande factors were determined by X-band ({approx}9.5 GHz), electron paramagnetic measurements (EPR) to be g=1.333, 1.364, and 1.402 for Ce ions in PbA, A = S, Se and Te, respectively. The small difference with the predicted Lande factor g of 10/7 for the {Gamma}{sub 7} (J=5/2) ground state was attributed to crystal-field admixture. - Highlights:: Black-Right-Pointing-Pointer Magnetic susceptibility of Pb{sub 1-x}Ce{sub x}A (A=Te, Se and S). Black-Right-Pointing-Pointer Computed the zero-field splitting of Ce{sup 3+} ion in lead chalcogenides. Black-Right-Pointing-Pointer Explained the existence of four Ce{sup 3+} sites in PbA (A=Te, Se and S).

  2. Growth and magnetic properties dependence of the Co–Cu/Cu films electrodeposited under high magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Franczak, Agnieszka, E-mail: agnieszka.franczak@mtm.kuleuven.be [Laboratoire d’Ingénierie et Sciences des Matériaux (LISM EA 4695), Université de Reims Champagne-Ardenne, UFR Sciences et Naturelles, Bat. 6, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2 (France); Department of Materials Science (MTM), KU Leuven, Kasteelpark Arenberg 44, 3001 Haverlee (Leuven) (Belgium); Levesque, Alexandra [Laboratoire d’Ingénierie et Sciences des Matériaux (LISM EA 4695), Université de Reims Champagne-Ardenne, UFR Sciences et Naturelles, Bat. 6, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2 (France); Zabinski, Piotr [Laboratory of Physical Chemistry and Electrochemistry, Faculty of Non-Ferrous Metals, AGH University of Science and Technology, al. A. Mickiewicza 30, 30059 Krakow (Poland); Li, Donggang [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, 314 Box, 110004 Shenyang (China); Czapkiewicz, Maciej [Department of Electronics, AGH University of Science and Technology, al. A. Mickiewicza 30, 30059 Krakow (Poland); Kowalik, Remigiusz [Laboratory of Physical Chemistry and Electrochemistry, Faculty of Non-Ferrous Metals, AGH University of Science and Technology, al. A. Mickiewicza 30, 30059 Krakow (Poland); Bohr, Frédéric [Laboratoire d’Ingénierie et Sciences des Matériaux (LISM EA 4695), Université de Reims Champagne-Ardenne, UFR Sciences et Naturelles, Bat. 6, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2 (France); and others

    2015-07-15

    The present work is focused on the investigations of magnetic properties dependence on microstructure of Co–Cu/Cu films electrodeposited under superimposed high magnetic field. The experimental results indicate a strong effect of an external magnetic field on the morphology of deposited films, more precisely on the Co:Cu ratio that determines the film growth. It is shown that the Co–Cu/Cu films electrodeposited without superimposed magnetic field consisted of two clearly visible features: compact film with incorporated granular particles. Under a superimposed external high magnetic field the privilege growth of the particles was induced. As a consequence, development of the well-defined branched structure of Co–Cu/Cu film was observed. In contrary, the phase compositional investigations do not reveal any changes in the phase formation during electrodeposition under magnetic field conditions. Thus, it is assumed that a strong growth of Co–Cu/Cu films in (111) direction under magnetic or non-magnetic electrodeposition conditions is related with the growth of Cu (111) plane and embedded into it some of the Co fcc atoms of same (111) orientation, as well as the Co hcp atoms that grows in the (002) direction. This non-equilibrium growth of Co–Cu/Cu films under magnetic deposition conditions affects strongly the magnetic properties of deposited films, revealing that films obtained under magnetic fields higher than 3 T were no more magnetic materials. - Highlights: • Co–Cu/Cu electrodeposits were obtained at elevated temperature under HMFs. • The effects of HMFs on microstructure and magnetic properties were investigated. • Interesting morphological changes due to HMFs has been observed. • Changes in Co:Cu ratio due to HMFs modified the magnetic properties of deposits.

  3. Experimental mathematics on the magnetic susceptibility of the square lattice Ising model

    Energy Technology Data Exchange (ETDEWEB)

    Boukraa, S [LPTHIRM and Departement d' Aeronautique, Universite de Blida (Algeria); Guttmann, A J; Jensen, I [ARC Centre of Excellence for Mathematics and Statistics of Complex Systems, Department of Mathematics and Statistics, University of Melbourne, Victoria 3010 (Australia); Hassani, S; Zenine, N [Centre de Recherche Nucleaire d' Alger, 2 Bd. Frantz Fanon, BP 399, 16000 Alger (Algeria); Maillard, J-M [LPTMC, Universite de Paris, Tour 24, 4eme etage, case 121, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Nickel, B [Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1 (Canada)], E-mail: boukraa@mail.univ-blida.dz, E-mail: tonyg@ms.unimelb.edu.au, E-mail: I.Jensen@ms.unimelb.edu.au, E-mail: maillard@lptmc.jussieu.fr, E-mail: maillard@lptl.jussieu.fr, E-mail: njzenine@yahoo.com

    2008-11-14

    We calculate very long low- and high-temperature series for the susceptibility {chi} of the square lattice Ising model as well as very long series for the five-particle contribution {chi}{sup (5)} and six-particle contribution {chi}{sup (6)}. These calculations have been made possible by the use of highly optimized polynomial time modular algorithms and a total of more than 150 000 CPU hours on computer clusters. The series for {chi} (low- and high-temperature regimes), {chi}{sup (5)} and {chi}{sup (6)} are now extended to 2000 terms. In addition, for {chi}{sup (5)}, 10 000 terms of the series are calculated modulo a single prime, and have been used to find the linear ODE satisfied by {chi}{sup (5)} modulo a prime. A diff-Pade analysis of the 2000 terms series for {chi}{sup (5)} and {chi}{sup (6)} confirms to a very high degree of confidence previous conjectures about the location and strength of the singularities of the n-particle components of the susceptibility, up to a small set of 'additional' singularities. The exponents at all the singularities of the Fuchsian linear ODE of {chi}{sup (5)} and the (as yet unknown) ODE of {chi}{sup (6)} are given: they are all rational numbers. We find the presence of singularities at w = 1/2 for the linear ODE of {chi}{sup (5)}, and w{sup 2} = 1/8 for the ODE of {chi}{sup (6)}, which are not singularities of the 'physical' {chi}{sup (5)} and {chi}{sup (6)}, that is to say the series solutions of the ODE's which are analytic at w = 0. Furthermore, analysis of the long series for {chi}{sup (5)} (and {chi}{sup (6)}) combined with the corresponding long series for the full susceptibility {chi} yields previously conjectured singularities in some {chi}{sup (n)}, n {>=} 7. The exponents at all these singularities are also seen to be rational numbers. We also present a mechanism of resummation of the logarithmic singularities of the {chi}{sup (n)} leading to the known power-law critical behaviour occurring in

  4. Developments in deep brain stimulation using time dependent magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Crowther, L.J.; Nlebedim, I.C.; Jiles, D.C.

    2012-03-07

    The effect of head model complexity upon the strength of field in different brain regions for transcranial magnetic stimulation (TMS) has been investigated. Experimental measurements were used to verify the validity of magnetic field calculations and induced electric field calculations for three 3D human head models of varying complexity. Results show the inability for simplified head models to accurately determine the site of high fields that lead to neuronal stimulation and highlight the necessity for realistic head modeling for TMS applications.

  5. 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.

  6. Magnetizing angle dependence of harmonics of magnetic induction and magnetostriction in electrical steel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, C.G. E-mail: cgkim@omega.sunmoon.ac.kr; Kim, H.C.; Ahn, S.J.; Cha, S.Y.; Chang, S.K

    2000-06-02

    The harmonics of magnetic induction and magnetostriction during AC magnetization in electrical steel were measured as a function of the magnetizing angle with respect to [0 0 1] axis, phi (cursive,open) Greek. The relative amplitudes of odd and even harmonics, respectively, for magnetic induction and magnetostriction decrease with the harmonic order, accompanying the contraction of the amplitudes. The decreasing contraction order of magnetostriction harmonics with phi (cursive,open) Greek is shown to be an even number multiple of that of magnetic induction. This relationship could provide an easy distinction of harmonics characteristics of magnetostriction from that of magnetic induction.

  7. Age-Dependent Susceptibility to Enteropathogenic Escherichia coli (EPEC Infection in Mice.

    Directory of Open Access Journals (Sweden)

    Aline Dupont

    2016-05-01

    Full Text Available Enteropathogenic Escherichia coli (EPEC represents a major causative agent of infant diarrhea associated with significant morbidity and mortality in developing countries. Although studied extensively in vitro, the investigation of the host-pathogen interaction in vivo has been hampered by the lack of a suitable small animal model. Using RT-PCR and global transcriptome analysis, high throughput 16S rDNA sequencing as well as immunofluorescence and electron microscopy, we characterize the EPEC-host interaction following oral challenge of newborn mice. Spontaneous colonization of the small intestine and colon of neonate mice that lasted until weaning was observed. Intimate attachment to the epithelial plasma membrane and microcolony formation were visualized only in the presence of a functional bundle forming pili (BFP and type III secretion system (T3SS. Similarly, a T3SS-dependent EPEC-induced innate immune response, mediated via MyD88, TLR5 and TLR9 led to the induction of a distinct set of genes in infected intestinal epithelial cells. Infection-induced alterations of the microbiota composition remained restricted to the postnatal period. Although EPEC colonized the adult intestine in the absence of a competing microbiota, no microcolonies were observed at the small intestinal epithelium. Here, we introduce the first suitable mouse infection model and describe an age-dependent, virulence factor-dependent attachment of EPEC to enterocytes in vivo.

  8. 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.

  9. Anisotropy of magnetic susceptibility analysis of the Cantera Ignimbrite, San Luis Potosi, México: flow source recognition

    Science.gov (United States)

    Caballero-Miranda, C. I.; Torres-Hernández, J. R.; Alva-Valdivia, L. M.

    2009-01-01

    Anisotropy of magnetic susceptibility (AMS) was selected as the key technique to find the source of the widespread Cantera Ignimbrite and to seek its possible relationship with the San Luis Potosí Caldera. Eighteen sites (372 specimens from 155 cores) from the Oligocene Cantera Ignimbrite were sampled. AMS was measured on a KLY2 Kappabridge. AMS data were processed with Anisoft 3 software using Jelinek statistics as well as `SpheriStat' principal components and density distribution. Mean susceptibilities range from 290 to 5026 × 10-6 SI (average = 2526 × 10-6 SI). The anisotropy degree ( P j) ranges from 1.005 to 1.055, with only one site displaying a value of 1.134 ( P j average = 1.031). AMS ellipsoid shapes are mostly oblate, with the T-factor ranging from 0.843 to 0.144 ( T average = 0.529), although one site is mainly prolate ( T = -0.005), and three additional sites have an important proportion of prolate specimens. Magnetic fabrics of most sites shows k3 axes around nearly circular distributions and k 1- k 2 axes around elongated-girdle distributions defining sub-horizontal foliation planes; exceptions to this are related to sites with a significant percentage of prolate specimens. Flow directions inferred from AMS analysis indicate several ignimbrite sources located along selected NW-SE linear features (faults and fractures such as El Potosino Fault) as well as along the rim of the caldera structure. The geometry of volcanic outcrops, the NW-SE faulting-fracture system, as well as the AMS results suggest that this is a caldera structure resembling the trapdoor-type (Lipman, 1997).

  10. Influenza infection suppresses NADPH oxidase-dependent phagocytic bacterial clearance and enhances susceptibility to secondary MRSA infection

    Science.gov (United States)

    Sun, Keer; Metzger, Dennis W.

    2014-01-01

    Methicillin-resistant S. aureus (MRSA) has emerged as a leading contributor to mortality during recent influenza pandemics. The mechanism for this influenza-induced susceptibility to secondary S. aureus infection is poorly understood. Here we show that innate antibacterial immunity was significantly suppressed during the recovery stage of influenza infection, despite the fact that MRSA super-infection had no significant effect on viral burdens. Compared to mice infected with bacteria alone, post-influenza MRSA infected mice exhibited impaired bacterial clearance, which was not due to defective phagocyte recruitment, but rather coincided with reduced intracellular reactive oxygen species (ROS) levels in alveolar macrophages and neutrophils. NADPH oxidase is responsible for ROS production during phagocytic bacterial killing, a process also known as oxidative burst. We found that gp91phox-containing NADPH oxidase activity in macrophages and neutrophils was essential for optimal bacterial clearance during respiratory MRSA infections. In contrast to WT animals, gp91phox−/− mice exhibited similar defects in MRSA clearance before and after influenza infection. Using gp91phox+/− mosaic mice, we further demonstrate that influenza infection inhibits a cell-intrinsic contribution of NADPH oxidase to phagocyte bactericidal activity. Together, our results establish that influenza infection suppresses NADPH oxidase-dependent bacterial clearance and leads to susceptibility to secondary MRSA infection. PMID:24563256

  11. Magnetization of a Current-Carrying Superconducting Disk with B-Dependent Critical Current Density

    Science.gov (United States)

    Sohrabi, Mahdi; Babaei-Brojeny, Ali A.

    2010-11-01

    In the frame work of the critical state model (CSM), the magnetic response of a thin type-II superconducting disk that carries a radial transport current and is subjected to an applied magnetic field have been studied. To this end, we have studied the process of the magnetic flux-penetration. For a disk initially containing no magnetic flux but carrying a radial current, when a perpendicular magnetic field is applied, magnetic flux-penetration occurs in three stages: (1) the magnetic flux gradually penetrates from the edges of the disk until an instability occurs, (2) there is a rapid inflow of magnetic flux into the disk’s central region, which becomes resistive, and (3) magnetic flux continues to enter the disk, while persistent azimuthal currents flow in an outer annular region where the net current density is equal to J c . Also the behavior of a current-carrying disk subjected to an AC magnetic field is calculated. The magnetic flux, the current profiles and the magnetization hysteresis loops are calculated for several commonly used J c ( B) dependences. Finally, the results of the applications of the local field-dependent of the critical current density J c ( B) are compared with those obtained from the Bean model.

  12. Temperature-dependent dynamic correlations in suspensions of magnetic nanoparticles in a broad range of concentrations: a combined experimental and theoretical study.

    Science.gov (United States)

    Ivanov, Alexey O; Kantorovich, Sofia S; Zverev, Vladimir S; Elfimova, Ekaterina A; Lebedev, Alexander V; Pshenichnikov, Alexander F

    2016-07-21

    The interweave of competing individual relaxations influenced by the presence of temperature and concentration dependent correlations is an intrinsic feature of superparamagnetic nanoparticle suspensions. This unique combination gives rise to multiple applications of such suspensions in medicine, nanotechnology and microfluidics. Here, using theory and experiment, we investigate dynamic magnetic susceptibility in a broad range of temperatures and frequencies. Our approach allows, for the first time to our knowledge, to separate clearly the effects of superparamagnetic particle polydispersity and interparticle magnetic interactions on the dynamic spectra of these systems. In this way, we not only provide a theoretical model that can predict well the dynamic response of magnetic nanoparticles systems, but also deepen the understanding of the dynamic nanoparticle self-assembly, opening new perspectives in tuning and controlling the magnetic behaviour of such systems in AC fields.

  13. Size-dependent magnetic transitions in CoFe0.1Cr1.9O4 nanoparticles studied by magnetic and neutron-polarization analysis.

    Science.gov (United States)

    Kumar, D; Galivarapu, J K; Banerjee, A; Nemkovski, K S; Su, Y; Rath, Chandana

    2016-04-29

    Multiferroic, CoCr2O4 bulk material undergoes successive magnetic transitions such as a paramagnetic to collinear and non-collinear ferrimagnetic state at the Curie temperature (TC) and spiral ordering temperature (TS) respectively and finally to a lock-in-transition temperature (Tl). In this paper, the rich sequence of magnetic transitions in CoCr2O4 after mixing the octahedral site with 10% of iron are investigated by varying the size of the particle from 10 to 50 nm. With the increasing size, while the TC increases from 110 to 119 K which is higher than the TC (95 K) of pure CoCr2O4, the TS remains unaffected. In addition, a compensation of magnetization at 34 K and a lock-in transition at 10 K are also monitored in 50 nm particles. Further, we have examined the magnetic-ordering temperatures through neutron scattering using a polarized neutron beam along three orthogonal directions after separating the magnetic scattering from nuclear-coherent and spin-incoherent contributions. While a sharp long-range ferrimagnetic ordering down to 110 K and a short-range spiral ordering down to 50 K are obtained in 50 nm particles, in 10 nm particles, the para to ferrimagnetic transition is found to be continuous and spiral ordering is diffused in nature. Frequency-dependent ac susceptibility (χ) data fitted with different phenomenological models such as the Neel-Arrhenius, Vogel-Fulcher and power law, while ruling out the canonical spin-glass, cluster-glass and interacting superparamagnetism, reveal that both particles show spin-glass behavior with a higher relaxation time in 10 nm particles than in 50 nm. The smaller spin flip time in 50 nm particles confirms that spin dynamics does not slow down on approaching the glass transition temperature (Tg).

  14. Size-dependent magnetic transitions in CoFe0.1Cr1.9O4 nanoparticles studied by magnetic and neutron-polarization analysis

    Science.gov (United States)

    Kumar, D.; Galivarapu, J. K.; Banerjee, A.; Nemkovski, K. S.; Su, Y.; Rath, Chandana

    2016-04-01

    Multiferroic, CoCr2O4 bulk material undergoes successive magnetic transitions such as a paramagnetic to collinear and non-collinear ferrimagnetic state at the Curie temperature (T C) and spiral ordering temperature (T S) respectively and finally to a lock-in-transition temperature (T l). In this paper, the rich sequence of magnetic transitions in CoCr2O4 after mixing the octahedral site with 10% of iron are investigated by varying the size of the particle from 10 to 50 nm. With the increasing size, while the T C increases from 110 to 119 K which is higher than the T C (95 K) of pure CoCr2O4, the T S remains unaffected. In addition, a compensation of magnetization at 34 K and a lock-in transition at 10 K are also monitored in 50 nm particles. Further, we have examined the magnetic-ordering temperatures through neutron scattering using a polarized neutron beam along three orthogonal directions after separating the magnetic scattering from nuclear-coherent and spin-incoherent contributions. While a sharp long-range ferrimagnetic ordering down to 110 K and a short-range spiral ordering down to 50 K are obtained in 50 nm particles, in 10 nm particles, the para to ferrimagnetic transition is found to be continuous and spiral ordering is diffused in nature. Frequency-dependent ac susceptibility (χ) data fitted with different phenomenological models such as the Neel-Arrhenius, Vogel-Fulcher and power law, while ruling out the canonical spin-glass, cluster-glass and interacting superparamagnetism, reveal that both particles show spin-glass behavior with a higher relaxation time in 10 nm particles than in 50 nm. The smaller spin flip time in 50 nm particles confirms that spin dynamics does not slow down on approaching the glass transition temperature (T g).

  15. Modalities of anisotropy of magnetic susceptibility in fine-grained sedimentary rocks deformed in a contraction-dominated setting - A case study of the Central Armorican Domain, Brittany, France

    OpenAIRE

    Haerinck, Tom

    2014-01-01

    An integrated rock-magnetic and mineralogical approach is performed for a case study of low-grade metasedimentary rocks from the Central Armorican Domain (CAD). The objective is twofold. Firstly, gaining a better understanding of the relation between the mineral sources of magnetic susceptibility and the anisotropy of magnetic susceptibility (AMS). Secondly, verifying whether the magnetic fabrics have a potential as a regional strain marker. For this goal, a lithostratigraphical reference uni...

  16. Percolation Model of the Temperature Dependence of Exotic Magnetic Field in Doped Manganese Perovskites

    Institute of Scientific and Technical Information of China (English)

    QU Shao-Hua; YAO Kai-Lun; LIU Zu-Li; FU Hua-Hua

    2005-01-01

    @@ We investigate the magnetic transitions in a (La1-xBx)2/3Ca1/3MnO3 system, which consists of paramagnetic and ferromagnetic domains, based on a magnetic theoretical percolation model In the mean-field approximation,the resistance as a function of temperature and magnetic field has been derived analytically and simulated numerically. It is found that the dependence of the critical temperature on magnetic field is linear when applied magnetic field is not too strong. Our theoretical predications are in good agreement with recent experimental observations.

  17. Grain size dependent magnetic discrimination of Iceland and South Greenland terrestrial sediments in the northern North Atlantic sediment record

    Science.gov (United States)

    Hatfield, Robert G.; Stoner, Joseph S.; Reilly, Brendan T.; Tepley, Frank J.; Wheeler, Benjamin H.; Housen, Bernard A.

    2017-09-01

    We use isothermal and temperature dependent in-field and magnetic remanence methods together with electron microscopy to characterize different sieved size fractions from terrestrial sediments collected in Iceland and southern Greenland. The magnetic fraction of Greenland silts (3-63 μm) and sands (>63 μm) is primarily composed of near-stoichiometric magnetite that may be oxidized in the finer clay (<3 μm) fractions. In contrast, all Icelandic fractions dominantly contain titanomagnetite of a range of compositions. Ferrimagnetic minerals preferentially reside in the silt-size fraction and exist as fine single-domain (SD) and pseudo-single-domain (PSD) size inclusions in Iceland samples, in contrast to coarser PSD and multi-domain (MD) discrete magnetites from southern Greenland. We demonstrate the potential of using magnetic properties of the silt fraction for source unmixing by creating known endmember mixtures and by using naturally mixed marine sediments from the Eirik Ridge south of Greenland. We develop a novel approach to ferrimagnetic source unmixing by using low temperature magnetic susceptibility curves that are sensitive to the different crystallinity and cation substitution characteristics of the different source regions. Covariation of these properties with hysteresis parameters suggests sediment source changes have driven the magnetic mineral variations observed in Eirik Ridge sediments since the last glacial maximum. These observations assist the development of a routine method and interpretative framework to quantitatively determine provenance in a geologically realistic and meaningful way and assess how different processes combine to drive magnetic variation in the North Atlantic sediment record.

  18. Seismic and magnetic susceptibility anisotropy of middle-lower continental crust: Insights for their potential relationship from a study of intrusive rocks from the Serre Massif (Calabria, southern Italy)

    Science.gov (United States)

    Punturo, Rosalda; Mamtani, Manish A.; Fazio, Eugenio; Occhipinti, Roberta; Renjith, A. R.; Cirrincione, Rosolino

    2017-08-01

    We investigated the relationships between fabric, seismic and magnetic anisotropy on lithotypes representative of a continental crust exposed in the Serre Massif (Southern Italy). In particular, from five granitoids and one metagabbro, cubes were cut according to the fabric elements and seismic properties up to 400 MPa confining pressure were measured with a triaxial multi-anvil apparatus; we also calculated the elastic properties based on the mineral content and composition. In granitoids, measured average compressional wave velocity (Vp) of the fracture-free aggregate at 400 MPa is 6.2 km/s, whereas average shear wave velocity (Vs) is 3.6 km/s, with Poisson's ratio ranging from 0.240 to 0.257, related to the modal proportions of quartz. In metagabbro, average Vp and Vs at 400 MPa are 6.9 km/s and 3.7 km/s, respectively. Results showed that intrinsic velocity distribution, after microcracks closure, depends on progressive alignment of anisotropic minerals such as biotite, amphibole and pyroxene, with maxima velocities localized within the foliation plane. Mean magnetic susceptibility, Km, of the granitic rocks is units, indicating that paramagnetic minerals such as biotite and amphibole control the intensity of magnetic anisotropy. Comparison of seismic and magnetic anisotropies highlighted the different role of constituting minerals over the petrophysical properties. Moreover, a positive correlation between seismic and magnetic anisotropy has been recognized, indicating that biotite and amphibole contribute to the petrophysical and textural anisotropy in the middle crust. Conversely, in metagabbro, the anisotropy of magnetic susceptibility (AMS) is controlled by magnetite and pyrrhotite although these form < 10% of the rock, which dominantly comprises paramagnetic minerals such as biotite and orthopyroxene. Unlike granitoids, in metagabbro the petrophysical properties are controlled by the paramagnetic minerals, while the magnetic anisotropy is controlled by the

  19. Pollution detected innovation of hazardous and toxic substance disposal by magnetic susceptibility method in Cikijing River, Rancaekek for testing water quality standards

    Science.gov (United States)

    Prananda, Yovan; Taufik, Febri; Alief, R.; Fikrianti, S.; M. Hardian, T.; Widodo

    2017-07-01

    Water pollution can defect surround the source of pollution. An example is Cikijing River, located in Rancaekek, Bandung which has expected contaminated by water disposal. Total loss approach by Total Economic Valuation is Rp 11.385.847.532.188 (± 11.4 trillion). One of the dangerous effect is the water quality in there. The aim of this research is to know and prove water disposal contaminated in that river. This research was conducted by mapping the magnetic anomaly which obtained from the surrounding river. Afterward, modeling the research is conducted to get the susceptibility value. In the previous research, the geological condition of our research field is Kosambi Formation (clay, sandstone, shale). The Kosambi Formation susceptibility value estimated 0.017cgs unit there after it used to be background susceptibility. As the result of modeling magnetic anomaly from the anomaly map, the susceptibility contrast shows negative value. The relation between magnetic anomaly and susceptibility indicated the hazardous and toxic substance pollution, which affected Cikijing River and around there.

  20. Rapamycin enhances the susceptibility of both androgen-dependent and-independent prostate carcinoma cells to docetaxel

    Institute of Scientific and Technical Information of China (English)

    LIU Qing-jun; XU Xiu-hong; SHANG Dong-hao; TIAN Ye; L(U) Wen-cheng; ZHANG Yu-hai

    2010-01-01

    Background Docetaxel (DOC) therapy is well tolerated and shows high response rates in patients with hormone refractory prostate cancer (HRPC). There are many reports on the effect of rapamycin (RPM) on the treatment of carcinogenesis. The goal of this study was to test whether RPM could enhance the susceptibility of both androgen-dependent and -independent prostate carcinoma cells to DOC.Methods Prostate cancer (PC) cell lines (LNCap, PC3 and AILNCap) were cultured and treated with RPM and DOC alone or in combination. The effects of therapeutic agents on cells were determined by the WST-1 assay. Apoptosis induction was confirmed by flow cytometric analysis. The apopcyto caspase colorimetric assay kit was applied to measure the activities of caspases 3 and 9. The antitumor effects of RPM and DOC against PC cells were also assessed in nude mice using four randomized groups: control, RPM, DOC and combination drug therapy by measuring tumor size. All the animals tolerated both RPM and DOC without significant weight loss.Results RPM and DOC caused dosage-dependent growth suppression of PC cells. RPM could increase the susceptibility of PC cells to DOC significantly, and combined treatment with RPM and DOC caused synergistic growth suppression in all examined PC cell lines by isobolographic analysis. Both RPM and DOC significantly induced apoptosis in a dosage-dependent manner. RPM (10 nmol/L), DOC (1 nmol/L), and combined treatment induced apoptosis rate were 8%, 17% and 38%, respectively (the control was 2%). RPM could promote the apoptosis induced by DOC in PC cell lines. Both RPM and DOC significantly increased the caspase activity in a dosage-dependent manner. The relative activities of caspase 9 in control, RPM, DOC and RPM+DOC groups were 0.22±0.02, 0.36±0.06, 0.47±0.05 and 0.84±0.08, respectively. The relative activities of cespase 3 were 0.21±0.02, 0.24±0.05, 0.42±0.06 and 0.81±0.09, respectively. Either RPM or DOC alone significantly inhibited the

  1. Using Bulk Magnetic Susceptibility to Resolve Internal and External Signals in the NMR Spectra of Plant Tissues

    Science.gov (United States)

    Shachar-Hill, Yair; Befroy, Douglas E.; Pfeffer, Philip E.; Ratcliffe, R. George

    1997-07-01

    Internal and external NMR signals from a variety of plant cells and plant tissues can be resolved by changing the bulk magnetic susceptibility (BMS) of the perfusing medium with [Gd (EDTA)]-or Dy(DTPA-BMA). This separation is observed in samples consisting of cylindrical cells oriented along theB0field, and is consistent with established theoretical predictions about BMS effects. Evidence is presented that the shifted signals represent material outside the tissue as well as some contribution from intercellular spaces and cell walls, while intracellular signals are unshifted. The paramagnetic complexes used to separate the signals are shown to be nontoxic and to have no effect on a number of transport processes. The method has been applied to roots, shoots, and giant algal cells, facilitating the interpretation of thein vivospectra from a range of biologically important magnetic isotopes. The potential of the method for studies of transport is illustrated with experiments showing: (i)14N/15N isotopic exchange of nitrate in roots; (ii) the influx of HDO into root and shoot segments; and (iii) the use of saturation transfer to follow water movement into and out of plant cells.

  2. Investigation of the field dependent spin structure of exchange coupled magnetic heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Gurieva, Tatiana

    2016-05-15

    This thesis describes the investigation of the field dependent magnetic spin structure of an antiferromagnetically (AF) coupled Fe/Cr heterostructure sandwiched between a hardmagnetic FePt buffer layer and a softmagnetic Fe top layer. The depth-resolved experimental studies of this system were performed via Magneto-optical Kerr effect (MOKE), Vibrating Sample Magnetometry (VSM) and various measuring methods based on nuclear resonant scattering (NRS) technique. Nucleation and evolution of the magnetic spiral structure in the AF coupled Fe/Cr multilayer structure in an azimuthally rotating external magnetic field were observed using NRS. During the experiment a number of time-dependent magnetic side effects (magnetic after-effect, domain-wall creep effect) caused by the non-ideal structure of a real sample were observed and later explained. Creation of the magnetic spiral structure in rotating external magnetic field was simulated using a one-dimensional micromagnetic model.The cross-sectional magnetic X-ray diffraction technique was conceived and is theoretically described in the present work. This method allows to determine the magnetization state of an individual layer in the magnetic heterostructure. It is also applicable in studies of the magnetic structure of tiny samples where conventional x-ray reflectometry fails.

  3. Size-dependent MR relaxivities of magnetic nanoparticles

    Science.gov (United States)

    Joos, Alexander; Löwa, Norbert; Wiekhorst, Frank; Gleich, Bernhard; Haase, Axel

    2017-04-01

    Magnetic nanoparticles (MNPs) can be used as carriers for magnetic drug targeting and for stem cell tracking by magnetic resonance imaging (MRI). For these applications, it is crucial to quantitatively determine the spatial distribution of the MNP concentration, which can be approached by MRI relaxometry. Theoretical considerations and experiments have shown that R2 relaxation rates are sensitive to the aggregation state of the particles, whereas R2* is independent of aggregation state and therefore suited for MNP quantification if the condition of static dephasing is met. We present a new experimental approach to characterize an MNP system with respect to quantitative MRI based on hydrodynamic fractionation. The first results qualitatively confirm the outer sphere relaxation theory for small MNPs and show that the two commercial MRI contrast agents Resovist® and Endorem® should not be used for quantitative MRI because they do not fulfill the condition for static dephasing. Our approach could facilitate the choice of MNPs for quantitative MRI and help clarifying the relationship between size, magnetism and relaxivity of MNPs in the future.

  4. Neuron firing frequency dependence on the static magnetic field intensity

    Science.gov (United States)

    Azanza, M. J.; del Moral, A.

    1995-02-01

    The effects of static magnetic field (SMF) of B intensity ( B = 0.003-0.72 T) on neurons are studied. The firing frequency f decreases exponentially with B2 and a threshold field B0 (≈ 0.57 T), where f abruptly drops to zero, is observed. A suitable model is developed where SMF's liberate membrane bounded Ca 2+ ions.

  5. The wavelength dependence of Faraday rotation in magnetic fluids

    Science.gov (United States)

    Yusuf, Nihad A.; Rousan, Akram A.; El-Ghanem, Hassan M.

    1988-09-01

    Measurements of Faraday rotation over the wavelength range 450-633 nm in a dilute Fe3O4 particle magnetic fluid are reported. The results, in agreement with the theory, show an enhancement of Faraday rotation near the wavelength λ≊500 nm.

  6. Millennial-centennial Scales Climate Changes of Holocene Indicated by Magnetic Susceptibility of High-resolution Section in Salawusu River Valley China

    Institute of Scientific and Technical Information of China (English)

    LU Yingxia; LI Baosheng; WEN Xiaohao; QIU Shifan; WANG Fengnian; NIU Dongfeng; LI Zhiwen

    2010-01-01

    The upmost segment(Holocene series)of the Milanggouwan stratigraphic section(MGS1)in the Salawusu River valley shows 11 sedimentary cycles of dune sands and fluvio-lacustrine facies,or dune sands and paleosols.The analysis of the magnetic susceptibility of this segment suggests that there are 11 magnetic susceptibility cycles with the value alternating from low to high,in which the layers of the dune sands correspond to the lower value of the magnetic susceptibility and the layers of fluvio-lacustrine facies and paleosols correspond to the higher peaks.The study reveals that the low and high magnetic susceptibility values indicate the climate dominated by cold-arid winter monsoon and warm-humid summer monsoon of East Asia,respectively,and the study area has experienced at least 22 times of mil-lennial-centennial scales climate alternation from the cold-arid to the warm-humid during the Holocene.In terms of the time and the climate nature,the variations basically correspond to those of the North Atlantic and some records of cold-warm changes in China as well.They might be caused by the alternation of winter and summer monsoons in the Mu Us Desert induced by global climate fluctuations in the Holocene.

  7. Magnetic susceptibility as a high-resolution correlation tool and as a climatic proxy in Paleozoic rocks - Merits and pitfalls: Examples from the Devonian in Belgium

    NARCIS (Netherlands)

    Da Silva, A.-C.; De Vleeschouwer, D.; Boulvain, F.; Claeys, P.; Fagel, N.; Humblet, M.; Mabille, C.; Michel, J.; Sardar Abadi, M.; Pas, D.; Dekkers, M.J.

    2013-01-01

    Low-field magnetic susceptibility (χin) measurements are quick and sensitive enabling the creation of high-resolution records; making χin an attractive correlation tool and a proxy for paleoclimate and paleoenvironments. In geologically young material – foremost in Cenozoic sediments – χin belongs t

  8. High-Resolution Magnetic Susceptibility Stratigraphy Spanning Late Devonian Global Change from a New Scientific Drillcore in Canning Basin, Northwest Australia

    Science.gov (United States)

    Diamond, M. R.; Raub, T. D.; Kirschvink, J. L.; Playton, T. E.; Hocking, R. M.; Haines, P.; Tulipani, S.

    2010-12-01

    New shallow scientific drillcore has been recovered through the Frasnian-Famennian extinction boundary in northwest Australia’s Canning Basin. Previous work in the McWhae Ridge outcrop belt has identified patterns of turnover in trilobites and other fauna, change from sponge- and coral-dominated reefs to post-extinction microbial-dominated reefs, apparent sea level changes, and carbon isotopic evidence of late Devonian crisis. Continuous magnetic susceptibility (MS) stratigraphy yields highly structured oscillations spanning ~42 m of reef-slope carbonate. These oscillations appear to identify late Frasnian “Kellwasser” events and they may record sedimentary response to orbital variations, establishing a high-resolution relative chronostratigraphy of late Devonian global change. Magnetic susceptibility stratigraphy has been proposed as a generally useful chronometer for late Devonian time. Most of fifteen published MS stratigraphies crossing the Frasnian-Famennian boundary appear to share major excursions with the new McWhae Ridge result. Although upland tectonism in Canning Basin may be a caveat to straightforward eustatic interpretation of magnetic susceptibility variations, we suggest the higher-resolution and fresh drillcore context of this result prioritizes it as a standard for Frasnian-Famennian magnetic susceptibility variation.

  9. Temperature Dependence and Magnetic Field Dependence of Quantum Point Contacts in Si-Inversion Layers

    NARCIS (Netherlands)

    Wang, S.L.; Son, P.C. van; Wees, B.J. van; Klapwijk, T.M.

    1992-01-01

    The conductance of ballistic point contacts in high-mobility Si-inversion layers has been studied at several temperatures between 75 and 600 mK both without and in a magnetic field (up to 12T). When the width of constriction is varied in zero magnetic field, step-like features at multiples of 4e2/h

  10. Field dependent magnetic anisotropy of Ga0.2Fe0.8 thin films

    Science.gov (United States)

    Resnick, Damon A.; McClure, A.; Kuster, C. M.; Rugheimer, P.; Idzerda, Y. U.

    2011-04-01

    Using longitudinal MOKE in combination with a variable strength rotating magnetic field, called the rotational MOKE (ROTMOKE) method, we show that the magnetic anisotropy for a Ga0.2Fe0.8 single crystal film with a thickness of 17 nm, grown on GaAs (001) with a thick ZnSe buffer layer, depends linearly on the strength of the applied magnetic field. The torque moment curves generated using ROTMOKE are well fit with a model that accounts for the uniaxial, cubic, or fourfold anisotropy, as well as additional terms with a linear dependence on the applied magnetic field. The uniaxial and cubic anisotropy fields, taken from both the hard and the easy axis scans, are seen to remain field independent. The field dependent terms are evidence of a large affect of the magnetostriction and its contribution to the effective magnetic anisotropy in GaxFe1-x thin films.

  11. Field dependent magnetic anisotropy of Fe1-xZnx thin films

    Science.gov (United States)

    Resnick, Damon A.; McClure, A.; Kuster, C. M.; Rugheimer, P.; Idzerda, Y. U.

    2013-05-01

    Using longitudinal magneto-optical Kerr effect in combination with a variable strength rotating magnetic field, called the Rotational Magneto-Optic Kerr Effect (ROTMOKE) method, we show that the magnetic anisotropy for thin Fe82Zn18 single crystal films, grown on MgO(001) substrates, depends linearly on the strength of the applied magnetic field at low fields but is constant (saturates) at fields greater than 350 Oe. The torque moment curves generated using ROTMOKE are well fit with a model that accounts for the uniaxial and cubic anisotropy with the addition of a cubic anisotropy that depends linearly on the applied magnetic field. The field dependent term is evidence of a large effect on the effective magnetic anisotropy in Fe1-xZnx thin films by the magnetostriction.

  12. Time-dependent rotatable magnetic anisotropy in polycrystalline exchange-bias systems: Dependence on grain-size distribution

    Science.gov (United States)

    Müglich, Nicolas David; Gaul, Alexander; Meyl, Markus; Ehresmann, Arno; Götz, Gerhard; Reiss, Günter; Kuschel, Timo

    2016-11-01

    Angular-resolved measurements of the exchange-bias field and the coercive field are a powerful tool to distinguish between different competing magnetic anisotropies in polycrystalline exchange-bias layer systems. No simple analytical model is as yet available which considers time-dependent effects such as enhanced coercivity in magnetic easy and hard axis configurations arising from the grain-size distribution of the antiferromagnet. In this work, we expand an existing model class describing polycrystalline exchange-bias systems by a rotatable magnetic anisotropy taking into account the relaxation time of thermally unstable grains. Our calculations show that coercivity mediated by the rotatable magnetic anisotropy can be distinguished from coercivity arising from ferromagnetic anisotropy by the shape of the angular dependence. Additionally, we performed angular-resolved magnetization curve measurements using vectorial magneto-optic Kerr magnetometry. Fitting the proposed model to the experimental data shows excellent agreement and reveals the ferromagnetic anisotropy and properties connected to the grain-size distribution of the antiferromagnet. Therefore, a distinction between the different influences on coercivity and magnetic anisotropy becomes available.

  13. Density dependent magnetic field and the equation of state of hyperonic matter

    CERN Document Server

    Casali, Rudiney Hoffmann

    2013-01-01

    We are interested on the effects, caused by strong variable density dependent magnetic fields, on hyperonic matter, its symmetry energy, equations of state and mass-radius relations. The inclusion of the anomalous magnetic moment of the particles involved in a stellar system is performed, and some results are compared with the cases that do not take this correction under consideration. The Lagrangian density used follows the nonlinear Walecka model plus the leptons subjected to an external magnetic field.

  14. 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.

  15. 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...

  16. Size-dependent magnetic properties of iron oxide nanoparticles

    Science.gov (United States)

    Patsula, Vitalii; Moskvin, Maksym; Dutz, Silvio; Horák, Daniel

    2016-01-01

    Uniform iron oxide nanoparticles in the size range from 10 to 24 nm and polydisperse 14 nm iron oxide particles were prepared by thermal decomposition of Fe(III) carboxylates in the presence of oleic acid and co-precipitation of Fe(II) and Fe(III) chlorides by ammonium hydroxide followed by oxidation, respectively. While the first method produced hydrophobic oleic acid coated particles, the second one formed hydrophilic, but uncoated, nanoparticles. To make the iron oxide particles water dispersible and colloidally stable, their surface was modified with poly(ethylene glycol) and sucrose, respectively. Size and size distribution of the nanoparticles was determined by transmission electron microscopy, dynamic light scattering and X-ray diffraction. Surface of the PEG-functionalized and sucrose-modified iron oxide particles was characterized by Fourier transform infrared (FT-IR) and Raman spectroscopy and thermogravimetric analysis (TGA). Magnetic properties were measured by means of vibration sample magnetometry and specific absorption rate in alternating magnetic fields was determined calorimetrically. It was found, that larger ferrimagnetic particles showed higher heating performance than smaller superparamagnetic ones. In the transition range between superparamagnetism and ferrimagnetism, samples with a broader size distribution provided higher heating power than narrow size distributed particles of comparable mean size. Here presented particles showed promising properties for a possible application in magnetic hyperthermia.

  17. [The magnetic susceptibility of the melanin in the eyes of representatives of different vertebrate classes].

    Science.gov (United States)

    Zagal'skaia, E O

    1995-01-01

    The magnetoperceptivity (Chi) and element composition of eye pigment epitelium (EPE) melanin in vertebrate animals were measured. The minimal values of EPE Chi were found in winter-sleeping and anabiotic animals (Ursus arctos, Rana temporaria). The magnetoperception was high in migrating animals (Oncorhynchus keta, 0. gorbuscha, Anas crecca) and in wild gray rats as well, EPE magnetoperceptivity in albino rats wasn't practicaly established. In the majority of cases the quantity of magnetoperceptivity correlates with per-cent content of iron. The evident correlation between melanin magnet properties and the life strategy of the investigated animals allows to propose the participance of eye pigment epithelium in orientation and navigation of the animals.

  18. Micafungin triggers caspase-dependent apoptosis in Candida albicans and Candida parapsilosis biofilms, including caspofungin non-susceptible isolates.

    Science.gov (United States)

    Shirazi, F; Kontoyiannis, D P

    2015-01-01

    Candida biofilms play an important role in infections associated with medical devices and are resistant to antifungals. We hypothesized that the echinocandin micafungin (MICA) exerts an enhanced antifungal activity against caspofungin (CAS)-susceptible (CAS-S) and CAS-non-susceptible (CAS-NS) Candida albicans and Candida parapsilosis which is at least in part through apoptosis, even in the biofilm environment. Apoptosis was characterized by detecting reactive oxygen species (ROS) accumulation, depolarization of mitochondrial membrane potential (MMP), DNA fragmentation, lack of plasma membrane integrity, and metacaspase activation following exposure of Candida biofilm to MICA for 3h at 37°C in RPMI 1640 medium. The minimum inhibitory concentration was higher for CAS (2.0-16.0 μg/mL) than for MICA (1.0-8.0 μg/mL) for Candida biofilms. Elevated intracellular ROS levels and depolarization of MMP was evident in CAS-S C. albicans (3.0-4.2 fold) and C. parapsilosis (4.8-5.4 fold) biofilms compared with CAS-NS (1.2 fold) after exposure to MICA (0.25x-1xMIC). Elevated intracellular ROS levels and depolarization of MMP was evident in CAS-S C. albicans (3.0-4.2 fold) and C. parapsilosis (4.8-5.4 fold) biofilms compared with CAS-NS (1.2 fold) after exposure to MICA (0.25x-1xMIC). Finally higher ß-1, 3 glucan levels were seen in sessile cells compared to planktonic cells, especially in CAS-NS strains. MICA treatment might induce a metacaspase-dependent apoptotic process in biofilms of both CAS-S C. albicans and C. parapsilosis, and to some degree in CAS-NS strains.

  19. Influence of magnetic fields on hysteretic ac losses in bulk MgB{sub 2} superconductor investigated by using Hall probe ac susceptibility method

    Energy Technology Data Exchange (ETDEWEB)

    Varilci, A [Faculty of Arts and Sciences, Department of Physics, Abant Izzet Baysal University, 14280 Bolu (Turkey)

    2007-04-15

    We report the results of an investigation of the influence of magnetic fields on hysteretic ac losses in bulk MgB{sub 2} superconductor by using Hall probe ac susceptibility. The external magnetic field in this study had an ac part with frequency 10 Hz and magnitude in the range 240-1200 A m{sup -1} and no dc part. We have measured the imaginary part of the magnetic susceptibility and analysed data by using Bean's critical state model of cylindrical geometry for four different temperature values 39.55, 39.51, 39.47 and 39.41 K. The result of this analysis indicates that Bean's model is adequate to explain the experimental findings. Calculated hysteretic ac loss versus applied magnetic field curve is given by using the critical state model. We have also measured the magnetization versus applied magnetic field and determined the first critical magnetic field of a MgB{sub 2} sample as 500 A m{sup -1} at 35 K.

  20. Polarized light modulates light-dependent magnetic compass orientation in birds.

    Science.gov (United States)

    Muheim, Rachel; Sjöberg, Sissel; Pinzon-Rodriguez, Atticus

    2016-02-09

    Magnetoreception of the light-dependent magnetic compass in birds is suggested to be mediated by a radical-pair mechanism taking place in the avian retina. Biophysical models on magnetic field effects on radical pairs generally assume that the light activating the magnetoreceptor molecules is nondirectional and unpolarized, and that light absorption is isotropic. However, natural skylight enters the avian retina unidirectionally, through the cornea and the lens, and is often partially polarized. In addition, cryptochromes, the putative magnetoreceptor molecules, absorb light anisotropically, i.e., they preferentially absorb light of a specific direction and polarization, implying that the light-dependent magnetic compass is intrinsically polarization sensitive. To test putative interactions between the avian magnetic compass and polarized light, we developed a spatial orientation assay and trained zebra finches to magnetic and/or overhead polarized light cues in a four-arm "plus" maze. The birds did not use overhead polarized light near the zenith for sky compass orientation. Instead, overhead polarized light modulated light-dependent magnetic compass orientation, i.e., how the birds perceive the magnetic field. Birds were well oriented when tested with the polarized light axis aligned parallel to the magnetic field. When the polarized light axis was aligned perpendicular to the magnetic field, the birds became disoriented. These findings are the first behavioral evidence to our knowledge for a direct interaction between polarized light and the light-dependent magnetic compass in an animal. They reveal a fundamentally new property of the radical pair-based magnetoreceptor with key implications for how birds and other animals perceive the Earth's magnetic field.

  1. Polarized light modulates light-dependent magnetic compass orientation in birds

    Science.gov (United States)

    Muheim, Rachel; Sjöberg, Sissel; Pinzon-Rodriguez, Atticus

    2016-01-01

    Magnetoreception of the light-dependent magnetic compass in birds is suggested to be mediated by a radical-pair mechanism taking place in the avian retina. Biophysical models on magnetic field effects on radical pairs generally assume that the light activating the magnetoreceptor molecules is nondirectional and unpolarized, and that light absorption is isotropic. However, natural skylight enters the avian retina unidirectionally, through the cornea and the lens, and is often partially polarized. In addition, cryptochromes, the putative magnetoreceptor molecules, absorb light anisotropically, i.e., they preferentially absorb light of a specific direction and polarization, implying that the light-dependent magnetic compass is intrinsically polarization sensitive. To test putative interactions between the avian magnetic compass and polarized light, we developed a spatial orientation assay and trained zebra finches to magnetic and/or overhead polarized light cues in a four-arm “plus” maze. The birds did not use overhead polarized light near the zenith for sky compass orientation. Instead, overhead polarized light modulated light-dependent magnetic compass orientation, i.e., how the birds perceive the magnetic field. Birds were well oriented when tested with the polarized light axis aligned parallel to the magnetic field. When the polarized light axis was aligned perpendicular to the magnetic field, the birds became disoriented. These findings are the first behavioral evidence to our knowledge for a direct interaction between polarized light and the light-dependent magnetic compass in an animal. They reveal a fundamentally new property of the radical pair-based magnetoreceptor with key implications for how birds and other animals perceive the Earth’s magnetic field. PMID:26811473

  2. Field dependence of the magnetic correlations of the frustrated magnet SrDy2O4

    Science.gov (United States)

    Gauthier, N.; Fennell, A.; Prévost, B.; Désilets-Benoit, A.; Dabkowska, H. A.; Zaharko, O.; Frontzek, M.; Sibille, R.; Bianchi, A. D.; Kenzelmann, M.

    2017-05-01

    The frustrated magnet SrDy2O4 exhibits a field-induced phase with a magnetization plateau at 1 /3 of the saturation value for magnetic fields applied along the b axis. We report here a neutron scattering study of the nature and symmetry of the magnetic order in this field-induced phase. Below T ≈0.5 K, there are strong hysteretic effects, and the order is short- or long-ranged for zero-field and field cooling, respectively. We find that the long-range ordered magnetic structure within the zigzag chains is identical to that expected for the one-dimensional axial next-nearest neighbor Ising (ANNNI) model in longitudinal fields. The long-range ordered structure in field contrasts with the short-range order found at zero field, and is probably reached through enhanced quantum fluctuations with increasing fields.

  3. Magnetic anisotropy of polycrystalline magnetoferritin investigated by SQUID and electron magnetic resonance

    Science.gov (United States)

    Moro, F.; de Miguel, R.; Jenkins, M.; Gómez-Moreno, C.; Sells, D.; Tuna, F.; McInnes, E. J. L.; Lostao, A.; Luis, F.; van Slageren, J.

    2014-06-01

    Magnetoferritin molecules with an average inorganic core diameter of 5.7±1.6 nm and polycrystalline internal structure were investigated by a combination of transmission electron microscopy, magnetic susceptibility, magnetization, and electron magnetic resonance (EMR) experiments. The temperature and frequency dependence of the magnetic susceptibility allowed for the determination of the magnetic anisotropy on an experimental time scale which spans from seconds to nanoseconds. In addition, angle-dependent EMR experiments were carried out for the determination of the nanoparticle symmetry and internal magnetic field. Due to the large surface to volume ratio, the nanoparticles show larger and uniaxial rather than cubic magnetic anisotropies compared to bulk maghemite and magnetite.

  4. Quark Mass Dependence of Nucleon Magnetic Moment and Charge Radii

    Institute of Scientific and Technical Information of China (English)

    MA Wei-Xing; ZHOU Li-Juan; GU Yun-Ting; PING Rong-Gang

    2005-01-01

    Understanding hadron structure within the framework of QCD is an extremely challenging problem. Our purpose here is to explain the model-independent consequences of the approximated chiral symmetry of QCD for two famous results concerning the quark structure of the nucleon. We show that both the apparent success of the constituent quark model in reproducing the ratio of proton to neutron magnetic moments and the apparent success of the Foldy term in reproducing the observed charge radius of the neutron are coincidental. That is, a relatively small change of the current quark mass would spoil both results.

  5. Angular Dependence of Lateral and Levitation Forces in Asymmetric Small Magnet/Superconducting Systems

    Institute of Scientific and Technical Information of China (English)

    H. M. Al-Khateeb; M. K. Alqadi; F. Y. Alzoubi; N. Y. Ayoub

    2007-01-01

    The dipole-dipole interaction model is used to calculate the angular dependence of lateral and levitation forces on a small permanent magnet and a cylindrical superconductor in the Meissner state lying laterally offthe symmetric axis of the cylinder. Under the assumption that the lateral displacement of the magnet is small compared with the physical dimensions of the system, we obtain analytical expressions for the lateral and levitation forces as functions of geometrical parameters of the superconductor as well as the height, the lateral displacement and the orientation of magnetic moment of the magnet. The effect of thickness and radius of the superconductor on the levitation force is similar to that for a symmetric magnet/superconducting cylinder system, but within the range of lateral displacement. The splitting in the levitation force increases with the increasing angle of orientation of the magnetic moment of the magnet. For a given lateral displacement of the magnet, the lateral force vanishes when the magnetic moment is perpendicular to the surface of the superconductor and has a maximum value when the moment is parallel to the surface. For a given orientation of the magnetic moment, the lateral force has a linear relationship with the lateral displacement. The stability of the magnet above the superconducting cylinder is discussed in detail.

  6. Estimation of the frequency and magnetic field dependence of the skin depth in Co-rich magnetic microwires from GMI experiments

    Directory of Open Access Journals (Sweden)

    Arcady Zhukov

    2016-09-01

    Full Text Available We studied giant magnetoimpedance (GMI effect in magnetically soft amorphous Co-rich microwires in the extended frequency range. From obtained experimentally dependences of the GMI ratio on magnetic field at different frequencies we estimated the penetration depth and its dependence on applied magnetic field and frequency.

  7. Magnetic field-dependent shape anisotropy in small patterned films studied using rotating magnetoresistance.

    Science.gov (United States)

    Fan, Xiaolong; Zhou, Hengan; Rao, Jinwei; Zhao, Xiaobing; Zhao, Jing; Zhang, Fengzhen; Xue, Desheng

    2015-11-13

    Based on the electric rotating magnetoresistance method, the shape anisotropy of a Co microstrip has been systematically investigated. We find that the shape anisotropy is dependent not only on the shape itself, but also on the magnetization distribution controlled by an applied magnetic field. Together with micro-magnetic simulations, we present a visualized picture of how non-uniform magnetization affects the values and polarities of the anisotropy constants K1 and K2. From the perspective of potential appliantions, our results are useful in designing and understanding the performance of micro- and nano-scale patterned ferromagnetic units and the related device properties.

  8. Acute Tumor Response to ZD6126 Assessed by Intrinsic Susceptibility Magnetic Resonance Imaging

    Directory of Open Access Journals (Sweden)

    Simon P. Robinson

    2005-05-01

    Full Text Available The effective magnetic resonance imaging (MRI transverse relaxation rate R2* was investigated as an early acute marker of the response of rat GH3 prolactinomas to the vascular-targeting agent, ZD6126. Multigradient echo (MGRE MRI was used to quantify R2*, which is sensitive to tissue deoxyhemoglobin levels. Tumor R2* was measured prior to, and either immediately for up to 35 minutes, or 24 hours following administration of 50 mg/kg ZD6126. Following MRI, tumor perfusion was assessed by Hoechst 33342 uptake. Tumor R2* significantly increased to 116 ± 4% of baseline 35 minutes after challenge, consistent with an ischemic insult induced by vascular collapse. A strong positive correlation between baseline R2* and the subsequent increase in R2* measured 35 minutes after treatment was obtained, suggesting that the baseline R2* is prognostic for the subsequent tumor response to ZD6126. In contrast, a significant decrease in tumor R2* was found 24 hours after administration of ZD6126. Both the 35-minute and 24-hour R2* responses to ZD6126 were associated with a decrease in Hoechst 33342 uptake. Interpretation of the R2* response is complex, yet changes in tumor R2* may provide a convenient and early MRI biomarker for detecting the antitumor activity of vascular-targeting agents.

  9. Temperature dependence of magnetism near defects in SrB sub 6

    CERN Document Server

    Jarlborg, T

    2003-01-01

    The temperature (T) dependence of magnetic moments in SrB sub 6 is studied through spin-polarized band calculations for a supercell of Sr sub 2 sub 7 B sub 1 sub 5 sub 6 containing a B sub 6 vacancy. The magnetic moment decays rather quickly with T despite the fact that only electronic Fermi-Dirac effects are included. This result and the T dependence of moments near an La impurity can hardly explain the reports of a very high Curie temperature in hexaborides, but suggest that the magnetism is caused by some other type of impurity. (letter to the editor)

  10. Radial oscillations of magnetized proto strange stars in temperature- and density-dependent quark mass model

    Indian Academy of Sciences (India)

    V K Gupta; Asha Gupta; S Singh; J D Anand

    2003-10-01

    We report on the study of the mass–radius (–) relation and the radial oscillations of magnetized proto strange stars. For the quark matter we have employed the very recent modification, the temperature- and density-dependent quark mass model of the well-known density-dependent quark mass model. We find that the effect of magnetic field, both on the maximum mass and radial frequencies, is rather small. Also a proto strange star, whether magnetized or otherwise, is more likely to evolve into a strange star rather than transform into a black hole.

  11. Temperature Dependence and Magnetic Properties of Injection Molding Tool Materials Used in Induction Heating

    DEFF Research Database (Denmark)

    Guerrier, Patrick; Nielsen, Kaspar Kirstein; Hattel, Jesper Henri

    2015-01-01

    , in this paper, been characterized for their temperature-dependent magnetic properties. The properties have been measured using a vibrating sample magnetometer, able to reach to 350 °C. The established material database comprises the B–H loops, from which the mean B–H curve, relative permeability versus magnetic......To analyze the heating phase of an induction heated injection molding tool precisely, the temperature-dependent magnetic properties, B–H curves, and the hysteresis loss are necessary for the molding tool materials. Hence, injection molding tool steels, core materials among other materials have...

  12. Time Dependent Influence of Rotating Magnetic Field on Bacterial Cellulose

    Directory of Open Access Journals (Sweden)

    Karol Fijałkowski

    2016-01-01

    Full Text Available The aim of the study was to assess the influence of rotating magnetic field (RMF on the morphology, physicochemical properties, and the water holding capacity of bacterial cellulose (BC synthetized by Gluconacetobacter xylinus. The cultures of G. xylinus were exposed to RMF of frequency that equals 50 Hz and magnetic induction 34 mT for 3, 5, and 7 days during cultivation at 28°C in the customized RMF exposure system. It was revealed that BC exposed for 3 days to RMF exhibited the highest water retention capacity as compared to the samples exposed for 5 and 7 days. The observation was confirmed for both the control and RMF exposed BC. It was proved that the BC exposed samples showed up to 26% higher water retention capacity as compared to the control samples. These samples also required the highest temperature to release the water molecules. Such findings agreed with the observation via SEM examination which revealed that the structure of BC synthesized for 7 days was more compacted than the sample exposed to RMF for 3 days. Furthermore, the analysis of 2D correlation of Fourier transform infrared spectra demonstrated the impact of RMF exposure on the dynamics of BC microfibers crystallinity formation.

  13. Spin-Dependent Hopping Transport in Magnetic Perovskites

    Science.gov (United States)

    Bruynseraede, Y.; Wagner, P.; Gordon, I.; Trappeniers, L.; Herlach, F.; Moshchalkov, V.

    1998-03-01

    Epitaxial films of Nd_0.5Sr_0.5MnO3 show a transition from paramagnetic-semiconducting to ferromagnetic-quasimetallic behavior at TC = 207 K and a colossal negative magnetoresistivity (CMR) of 750 % at 150 K, 12 T. Hall effect studies indicate a slightly increasing carrier density at the para- to ferromagnetic transition from 0.3 to 0.5 holes per unit cell. External magnetic fields do not affect these densities and the CMR effect is therefore caused by a field-induced enhancement of carrier mobility. The mobility gain can be described by a Mott-type model in which the hopping barrier is extended by a term related to the mutual spin orientation at neighbouring hopping sites, i. e. Mn ions of different valency. This model predicts a scaling behaviour of the CMR effect at constant temperature proportional to the Brillouin function \\cal B in the ferromagnetic state, and to \\cal B^2 for the paramagnet. Both results are confirmed by CMR measurements in pulsed magnetic fields up to 50 T.

  14. Secondary magnetic field harmonics dependence on vacuum beam chamber geometry

    Directory of Open Access Journals (Sweden)

    S. Y. Shim

    2013-08-01

    Full Text Available The harmonic magnetic field properties due to eddy currents have been studied with respect to the geometry of the vacuum beam chamber. We derived a generalized formula enabling the precise prediction of any field harmonics generated by eddy currents in beam tubes with different cross-sectional geometries. Applying our model to study the properties of field harmonics in beam tubes with linear dipole magnetic field ramping clearly proved that the circular cross section tube generates only a dipole field from eddy currents. The elliptic tube showed noticeable magnitudes of sextupole and dipole fields. We demonstrate theoretically that it is feasible to suppress the generation of the sextupole field component by appropriately varying the tube wall thickness as a function of angle around the tube circumference. This result indicates that it is possible to design an elliptical-shaped beam tube that generates a dipole field component with zero magnitude of sextupole. In a rectangular-shaped beam tube, one of the selected harmonic fields can be prevented if an appropriate wall thickness ratio between the horizontal and vertical tube walls is properly chosen. Our generalized formalism can be used for optimization of arbitrarily complex-shaped beam tubes, with respect to suppression of detrimental field harmonics.

  15. Investigation on magnetic field dependent modulus of epoxidized natural rubber based magnetorheological elastomer

    Science.gov (United States)

    Yunus, N. A.; Mazlan, S. A.; Ubaidillah; Aziz, S. A. A.; Khairi, M. H. Ahmad; Wahab, N. A. A.; Shilan, S. T.

    2016-11-01

    This paper presents an investigation on the use of epoxidized natural rubber (ENR) as a matrix of magnetorheological elastomers (MREs). Isotropic ENR-based MRE samples were synthesized by homogeneously mixed the ENR compound with carbonyl iron particles (CIPs). The microstructure of the sample was observed, and the magnetic field-dependent moduli were analyzed using rheometer. The influences of excitation frequency, CIPs content and magnetic field on the field-dependent moduli of ENR-based MREs were evaluated through dynamic shear test. The microstructure of MRE samples demonstrated the dispersed CIPs in the ENR matrix. The remarkable increment of storage and loss moduli of the ENR-based MREs has exhibited the magnetically controllable storage and loss moduli of the samples when exposed to the magnetic field. Consequently, the CIPs content, frequency and magnetic field were significantly influenced the dynamic moduli of the ENR-based MREs.

  16. Dissociation of O(2-)2 defects into paramagnetic O(-) in wide band-gap insulators - A magnetic susceptibility study of magnesium oxide

    Science.gov (United States)

    Batllo, F.; Leroy, R. C.; Parvin, K.; Freund, F.

    1990-01-01

    The magnetic susceptibility of single-crystal MgO has been measured in the temperature range 300-1000 K, using a Faraday balance. The high-purity crystal (less than 100 ppm transition metals), grown from the melt in a H2O-containing atmosphere, was found to be paramagnetic due to the presence of defects on the O(2-) sublattice. The defects derive from OH(-) introduced into the MgO matrix by the dissolution of traces of H2O during crystal growth. The OH(-) converts into O(2-)2 and H2. Each O(2-)2 represents two coupled, spin-paired O(-) states. The observed strongly temperature-dependent paramagnetism can be described by three contributions that overlay the intrinsic diamagnetism of MgO and arise from the low level of transition-metal impurities, O(-) generated by 0(2-)2 dissociation, and O(-) states trapped by quenching from high temperatures from previous experiments.

  17. Specific heat and frequency-dependent ac-susceptibility of PrNi2 below 1 K

    Science.gov (United States)

    Greidanus, F. J. A. M.; De Jongh, L. J.; Huiskamp, W. J.; Buschow, K. H. J.

    1982-01-01

    Ac-susceptibility measurements on PrNi2 show broad anomalies, the temperature of the susceptibility maximum shifting from 0.3-0.5 K as the frequency is varied in between 3 Hz and 3 kHz. On the other hand the specific heat is featureless in the same temperature range. The behaviour is interpreted in terms of a mixed electronic-nuclear phase transition. Strong relaxation effects are observed in the susceptibility at temperatures close to the maxima.

  18. Time as An Important Soil-Forming Factor Influencing Modern and Ancient Magnetic Susceptibility Enhancement Along the Delaware River Valley, USA

    Science.gov (United States)

    Stinchcomb, G. E.; Peppe, D. J.; Driese, S. G.

    2011-12-01

    Magnetic susceptibility is an increasingly popular low-cost method for rapidly assessing paleoclimate and paleoenvironmental impact on buried soils. The goal of this study is to determine the primary influence(s) on soil magnetic susceptibility along floodplain, terrace and upland soils in the middle Delaware River Valley, USA, using environmental magnetic, pedologic, and stratigraphic techniques. Two-hundred thirty samples were collected from age-constrained sandy, quartz-rich, floodplain, terrace, and upland soils (Entisols, Inceptisols). A Kruskal-Wallis (K-W) and post-hoc Tukey-Kramer (T-K) (α=0.05) multiple comparisons analysis on 176 mass-specific low-field susceptibility (Xlf) assays show that A and B horizons are magnetically enhanced compared to C and E horizons (p<0.0001). Results of descriptive soil micromorphology show that A and B horizons contain anywhere from 10-50% more amorphous organic matter and clay films along pores than do C and E horizons. Enhanced Xlf values also correlate positively (R^2=0.63) with the soil molecular weathering ratio of Alumina/Bases, suggesting that increased weathering likely results in the formation of pedogenic magnetic minerals and enhanced magnetic susceptibility signal. Additional K-W and T-K testing show that Xlf results, when grouped by floodplain-terrace designation (i.e., chronofunction) are significantly different (p<0.0001). The older T3 terrace and upland Xlf values (0.34±0.14 10^-6 m^3 kg^-1) are greater than the younger T2 terrace (0.18±0.06 10^-6 m^3 kg^-1) values, which are greater than modern floodplain (0.09±0.01 10^-6 m^3 kg^-1) Xlf values. These data suggest that longer intervals of soil formation enhance the Χlf value. This hypothesis is further supported when 159 Xlf values are plotted vs. age for the entire Holocene. A locally-weighted regression smoothing curve (LOESS) shows two distinct intervals of magnetic enhancement during previously established dry intervals, the early and late

  19. Model analysis of magnetic susceptibility of Sr2IrO4 : A two-dimensional Jeff=1/2 Heisenberg system with competing interlayer couplings

    Science.gov (United States)

    Takayama, Tomohiro; Matsumoto, Akiyo; Jackeli, George; Takagi, Hidenori

    2016-12-01

    We report the analysis of magnetic susceptibility χ (T ) of Sr2IrO4 single crystal in the paramagnetic phase. We formulate the theoretical susceptibility based on isotropic Heisenberg antiferromagnetism incorporating the Dzyaloshinsky-Moriya interaction exactly, and include the interlayer couplings in a mean-field approximation. χ (T ) above TN was found to be well described by the model, indicating the predominant Heisenberg exchange consistent with the microscopic theory. The analysis points to a competition of nearest and next-nearest-neighbor interlayer couplings, which results in the up-up-down-down configuration of the in-plane canting moments identified by the diffraction experiments.

  20. A nonlinear stability analysis in a double-diffusive magnetized ferrofluid with magnetic-field-dependent viscosity saturating a porous medium

    National Research Council Canada - National Science Library

    Sunil; Mahajan, Amit

    2009-01-01

    A rigorous nonlinear stability result is derived by introducing a suitable generalized energy functional for a magnetized ferrofluid layer heated and soluted from below with magnetic-field-dependent (MFD...

  1. A blood-oxygenation-dependent increase in blood viscosity due to a static magnetic field.

    Science.gov (United States)

    Yamamoto, Toru; Nagayama, Yuki; Tamura, Mamoru

    2004-07-21

    As the magnetic field of widely used MR scanners is one of the strongest magnetic fields to which people are exposed, the biological influence of the static magnetic field of MR scanners is of great concern. One magnetic interaction in biological subjects is the magnetic torque on the magnetic moment induced by biomagnetic substances. The red blood cell is a major biomagnetic substance, and the blood flow may be influenced by the magnetic field. However, the underlying mechanisms have been poorly understood. To examine the mechanisms of the magnetic influence on blood viscosity, we measured the time for blood to fall through a glass capillary inside and outside a 1.5 T MR scanner. Our in vitro results showed that the blood viscosity significantly increased in a 1.5 T MR scanner, and also clarified the mechanism of the interaction between red blood cells and the external magnetic field. Notably, the blood viscosity increased depending on blood oxygenation and the shear rate of the blood flow. Thus, our findings suggest that even a 1.5 T magnetic field may modulate blood flow.

  2. Effect of Low-Frequency Alternative-Current Magnetic Susceptibility in Ni80Fe20 Thin Films

    Directory of Open Access Journals (Sweden)

    Yuan-Tsung Chen

    2012-01-01

    Full Text Available X-ray diffraction (XRD results indicate that the NiFe thin films had a face-centered cubic (FCC structure. Post-annealing treatment increased the crystallinity of NiFe films over those at room temperature (RT, suggesting that NiFe crystallization yields FCC (111 texturing. Post-annealing treatments increase crystallinity over that obtained at RT. This paper focuses on the maximum alternative-current magnetic susceptibility (χac value of NiFe thin films with resonance frequency (fres at low frequencies from 10 Hz to 25000 Hz. These results demonstrate that the χac of NiFe thin films increased with post-annealing treatment and increasing thickness. The NiFe (111 texture suggests that the relationship between magneto-crystalline anisotropy and the maximum χac value with optimal resonance frequency (fres increased spin sensitivity at optimal fres. The results obtained under the three conditions revealed that the maximum χac value and optimal fres of a 1000 Å-thick NiFe thin film are 3.45 Hz and 500 Hz, respectively, following postannealing at TA=250°C for 1 h. This suggests that a 1000 Å NiFe thin film post-annealed at TA=250°C is suitable for gauge sensor and transformer applications at low frequencies.

  3. Magnetic susceptibility variations of the Ediacaran cap carbonates in the Yangtze platform and their implications for paleoclimate

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Magnetic susceptibility (MS) data were obtained from 11 sections of the Doushantuo (Ediacaran) cap carbonate that directly overlies the Nantuo glacial diamictite in the southeastern margin of the Yangtze platform. The MS data revealed two regionally correlatable peaks at the bottom and top of the cap carbonate, separated by an interval of low values. The lower MS peak coincides with high percentage of insoluble siliciclastic residues that are compositionally identical to the matrix of the underlying diamictite, suggesting its origin controlled mainly by detrital components during the first phase of cap carbonate deposition at the end of the glaciation. The upper MS peak is associated with high clay content and iron sulfides, and can be interpreted as either derived from enhanced greenhouse weathering that could have brought more terrigenous components into the ocean, or the result of ocean anoxia at the late stage of cap carbonate deposition that could led to formation of abundant iron sulfides. The regionally consistent MS curves from the cap carbonates provided the first geophysical record for the rapid climate change from icehouse to greenhouse conditions in the aftermath of the Neoproterozoic "snowball Earth" event.

  4. Comparative research on soil magnetic susceptibility and Chroma and grain of grassland soil and farmland soil in alpine region

    Science.gov (United States)

    Jie, Yuan; Guangchao, Cao; Chongyi, E.; Gang, Jiang; Youjing, Yuan; Cheng, Xiang

    2017-03-01

    This thesis aims at researching unchanged perennial farmland and grassland soil on the northern of Qinghai Lake basin and differences between soil magnetic susceptibility, chroma and soil particle size composition of grassland and farmland in lengthways profile(0-60cm). The result shows that the distinction of Xlf between grassland and farmland is smaller above 15cm, and farmland Xlf is finer than grassland below 15cm. The Xfd of grassland is finer than farmland above 30cm, which has a little difference below 30cm. Farmland chroma value is finer than the grassland generally. The lightness of grassland has increased trend and farmland has the decrease trend above 30cm, the lightness of grassland and farmland has no other changes below 30cm, the change of redness and yellowness in lengthways profile has a decrease trend from 0 to 60cm; the clay and silt content of grassland are finer than farmland except sand content; the sand maximum content of farmland in 0-10cm segment; 20 to 35 cm segment sand content decrease and began to increase from 35-60cm segment; the soil particle size composition has a big difference, in particular, when it is above 30cm, it has a little difference below 30cm.

  5. A study on transformation of some transition metal oxides in molten steelmaking slag to magnetically susceptible compounds

    Directory of Open Access Journals (Sweden)

    Shatokha V.

    2013-01-01

    Full Text Available Sustainable development of steelmaking requires solving a number of environmental problems. Economically feasible and environmentally friendly recycling of slag wastes is of special concern. Research of the team representing National Metallurgical Academy of Ukraine, Royal Institute of Technology, Carnegie Mellon University and URS Corp revealed a possibility of the controlled phase transformations in the liquid silicate melts followed by formation of the magnetically susceptible compounds. This approach enables selective recovery of metal values from slag. In this paper, the results obtained and further research directions are discussed. A possibility to exploit physical properties of the transition metals, typical for the metallurgical slags (such as Fe, Mn, V and others, and corresponding specific properties of their compounds, such as non-stoichiometry, mixed valency, pseudomorphosis, thermodynamic stability etc, in production of value-added materials from slag wastes is discussed. The results of the studies of thermodynamics and kinetics of oxidation in slags followed by phase transformation with binary, ternary and complex oxides under various physicochemical conditions are discussed in the view of their application for production of the materials with predefined physical properties. Peculiarities of precipitation in slags with various basicities are analysed and demonstrate capacity of the proposed approach in the production of the material with a given structure and size - for example, nano-sized crystals with structure of spinel. The approaches towards industrial realization of the developed method are also discussed.

  6. Temperature Dependence of Magnetization at Zero Applied Magnetic Field in Nearly Two Dimensional Ferromagnets

    Science.gov (United States)

    Widodo, Chomsin S.; Fujii, Muneaki

    2012-12-01

    NMR measurement have been made at low temperatures on the crystal structure of K2CuF4 and (C3H7NH3)2CuCl4 at zero applied magnetic field. 63Cu, 65Cu and 35Cl NMR have been used to measure spontaneous magnetization at the temperature range 2 K down to 30 mK. We have made the NMR experiments using a 3He-4He dilution refrigerator by conventional pulsed NMR method without external magnetic field. The magnetization at zero applied magnetic field in the nearly two-dimensional ferromagnet K2CuF4 of the experimental data is in a good agreement with Yamaji-Kondo theory and θc = 0.3, which is applied the double-time Green's function method incorporated with Tyablikov's decoupling. For temperature 1.1 K down to 0.26 K, the spontaneous magnetization of (C3H7NH3)2CuCl4 is support (t log t')-formalism from the spin wave theory.

  7. A cluster-glass magnetic state in R5Pd2 (R = Ho, Tb) compounds evidenced by AC-susceptibility and neutron scattering measurements.

    Science.gov (United States)

    Gubkin, A F; Sherstobitova, E A; Terentyev, P B; Hoser, A; Baranov, N V

    2013-06-12

    AC- and DC-susceptibility, high-field magnetization and neutron diffraction measurements have been performed in order to study the magnetic state of R5Pd2 (R = Ho, Tb) compounds. The results show that both compounds undergo cluster-glass freezing upon cooling below Tf. According to the neutron diffraction a long-range magnetic order is absent down to 2 K and magnetic clusters with short-range incommensurate antiferromagnetic correlations exist not only below Tf but also in a wide temperature range above the freezing temperature (at least up to 2Tf). A complex cluster-glass magnetic state existing in Ho5Pd2 and Tb5Pd2 down to low temperatures results in rather complicated magnetization behavior in DC and AC magnetic fields. Such an unusual magnetic state in compounds with a high rare-earth concentration may be associated with the layered type of their crystal structure and with substantial atomic disorder, which results in frustrations in the magnetic subsystem.

  8. Origin of the magnetic-field dependence of the nuclear spin-lattice relaxation in iron

    CERN Document Server

    Seewald, G; Körner, H J; Borgmann, D; Dietrich, M

    2008-01-01

    The magnetic-field dependence of the nuclear spin-lattice relaxation at Ir impurities in Fe was measured for fields between 0 and 2 T parallel to the [100] direction. The reliability of the applied technique of nuclear magnetic resonance on oriented nuclei was demonstrated by measurements at different radio-frequency (rf) field strengths. The interpretation of the relaxation curves, which used transition rates to describe the excitation of the nuclear spins by a frequency-modulated rf field, was confirmed by model calculations. The magnetic-field dependence of the so-called enhancement factor for rf fields, which is closely related to the magnetic-field dependence of the spin-lattice relaxation, was also measured. For several magnetic-field-dependent relaxation mechanisms, the form and the magnitude of the field dependence were derived. Only the relaxation via eddy-current damping and Gilbert damping could explain the observed field dependence. Using reasonable values of the damping parameters, the field depe...

  9. Temperature dependence of the magnetization of disc shaped NiO nanoparticles

    DEFF Research Database (Denmark)

    Klausen, Stine Nyborg; Lindgard, P.A.; Lefmann, Kim

    2002-01-01

    as a temperature dependent contribution of a structural peak in contrast to bulk NiO. The two magnetic signals vanish at the same temperature. The data are interpreted on the basis of an extended mean field model on disc shaped NiO particles. This model includes the finite size dependence of the effective field...

  10. Perpendicular magnetic anisotropy at the interface between ultrathin Fe film and MgO studied by angular-dependent x-ray magnetic circular dichroism

    Energy Technology Data Exchange (ETDEWEB)

    Okabayashi, J. [Research Center for Spectrochemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Koo, J. W.; Mitani, S. [National Institute for Materials Science (NIMS), Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8577 (Japan); Sukegawa, H. [National Institute for Materials Science (NIMS), Tsukuba 305-0047 (Japan); Takagi, Y.; Yokoyama, T. [Institute of Molecular Science, Okazaki, Aichi 444-8585 (Japan)

    2014-09-22

    Interface perpendicular magnetic anisotropy (PMA) in ultrathin Fe/MgO (001) has been investigated using angular-dependent x-ray magnetic circular dichroism (XMCD). We found that anisotropic orbital magnetic moments deduced from the analysis of XMCD contribute to the large PMA energies, whose values depend on the annealing temperature. The large PMA energies determined from magnetization measurements are related to those estimated from the XMCD and the anisotropic orbital magnetic moments through the spin-orbit interaction. The enhancement of anisotropic orbital magnetic moments can be explained mainly by the hybridization between the Fe 3d{sub z}{sup 2} and O 2p{sub z} states.

  11. Molecular network, pathway, and functional analysis of time-dependent gene changes associated with pancreatic cancer susceptibility to oncolytic vaccinia virotherapy

    Directory of Open Access Journals (Sweden)

    Dana Haddad

    2016-01-01

    Conclusions: Our study reveals the ability to assess time-dependent changes in gene expression patterns in pancreatic cancer cells associated with infection and susceptibility to vaccinia viruses. This suggests that molecular assays may be useful to develop safer and more efficacious oncolyticvirotherapies and support the idea that these treatments may target pathways implicated in pancreatic cancer resistance to conventional therapies.

  12. Composition dependent behavior in the ternary mixed magnetic insulator Co{sub 1−x}Mn{sub y}Ni{sub x−y}Cl{sub 2}·2H{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    DeFotis, G.C., E-mail: gxdefo@wm.edu; Hampton, A.S.; Wallin, T.J.; Trowell, K.T.; Pothen, J.M.; Welshhans, E.A.; Havas, K.C.

    2016-05-01

    The properties of ternary mixed magnetic Co{sub 1−x}Mn{sub y}Ni{sub x−y}Cl{sub 2}·2H{sub 2}O are examined by dc magnetization and susceptibility measurements, from 1.8 to 300 K as a function of composition. This is only the second ternary magnetic insulator so studied. The three transition metal chloride dihydrate components are known to differ in the degree of spin anisotropy and in the distribution of ferromagnetic and antiferromagnetic exchange interactions within and between strongly coupled chemical and structural chains. The Curie and Weiss constants, in χ{sub M}=C/(T−θ) fits to high temperature susceptibilities, are compared with weighted averages of pure component values. The observed Weiss constant is almost uniformly less negative than calculated. Maxima in low temperature susceptibilities vary widely in presence and location with composition. Some compositions exhibit no susceptibility maximum, many exhibit one maximum, and three exhibit two maxima. A T(x,y) diagram is constructed. Magnetization vs field isotherms exhibit different shapes as a function of composition, with hysteresis markedly composition dependent. For three mixtures hysteresis loops are studied as a function of temperature. An activation process model does not describe the temperature dependence well.

  13. Magnetic Modes in Rare Earth Perovskites: A Magnetic-Field-Dependent Inelastic Light Scattering study

    Science.gov (United States)

    Saha, Surajit; Cao, Bing-Chen; Motapothula, M.; Cong, Chun-Xiao; Sarkar, Tarapada; Srivastava, Amar; Sarkar, Soumya; Patra, Abhijeet; Ghosh, Siddhartha; Ariando; Coey, J. M. D.; Yu, Ting; Venkatesan, T.

    2016-11-01

    Here, we report the presence of defect-related states with magnetic degrees of freedom in crystals of LaAlO3 and several other rare-earth based perovskite oxides using inelastic light scattering (Raman spectroscopy) at low temperatures in applied magnetic fields of up to 9 T. Some of these states are at about 140 meV above the valence band maximum while others are mid-gap states at about 2.3 eV. No magnetic impurity could be detected in LaAlO3 by Proton-Induced X-ray Emission Spectroscopy. We, therefore, attribute the angular momentum-like states in LaAlO3 to cationic/anionic vacancies or anti-site defects. Comparison with the other rare earth perovskites leads to the empirical rule that the magnetic-field-sensitive transitions require planes of heavy elements (e.g. lanthanum) and oxygen without any other light cations in the same plane. These magnetic degrees of freedom in rare earth perovskites with useful dielectric properties may be tunable by appropriate defect engineering for magneto-optic applications.

  14. Magnetic Modes in Rare Earth Perovskites: A Magnetic-Field-Dependent Inelastic Light Scattering study

    Science.gov (United States)

    Saha, Surajit; Cao, Bing-Chen; Motapothula, M.; Cong, Chun-Xiao; Sarkar, Tarapada; Srivastava, Amar; Sarkar, Soumya; Patra, Abhijeet; Ghosh, Siddhartha; Ariando; Coey, J. M. D.; Yu, Ting; Venkatesan, T.

    2016-01-01

    Here, we report the presence of defect-related states with magnetic degrees of freedom in crystals of LaAlO3 and several other rare-earth based perovskite oxides using inelastic light scattering (Raman spectroscopy) at low temperatures in applied magnetic fields of up to 9 T. Some of these states are at about 140 meV above the valence band maximum while others are mid-gap states at about 2.3 eV. No magnetic impurity could be detected in LaAlO3 by Proton-Induced X-ray Emission Spectroscopy. We, therefore, attribute the angular momentum-like states in LaAlO3 to cationic/anionic vacancies or anti-site defects. Comparison with the other rare earth perovskites leads to the empirical rule that the magnetic-field-sensitive transitions require planes of heavy elements (e.g. lanthanum) and oxygen without any other light cations in the same plane. These magnetic degrees of freedom in rare earth perovskites with useful dielectric properties may be tunable by appropriate defect engineering for magneto-optic applications. PMID:27845368

  15. Magnetic Modes in Rare Earth Perovskites: A Magnetic-Field-Dependent Inelastic Light Scattering study.

    Science.gov (United States)

    Saha, Surajit; Cao, Bing-Chen; Motapothula, M; Cong, Chun-Xiao; Sarkar, Tarapada; Srivastava, Amar; Sarkar, Soumya; Patra, Abhijeet; Ghosh, Siddhartha; Ariando; Coey, J M D; Yu, Ting; Venkatesan, T

    2016-11-15

    Here, we report the presence of defect-related states with magnetic degrees of freedom in crystals of LaAlO3 and several other rare-earth based perovskite oxides using inelastic light scattering (Raman spectroscopy) at low temperatures in applied magnetic fields of up to 9 T. Some of these states are at about 140 meV above the valence band maximum while others are mid-gap states at about 2.3 eV. No magnetic impurity could be detected in LaAlO3 by Proton-Induced X-ray Emission Spectroscopy. We, therefore, attribute the angular momentum-like states in LaAlO3 to cationic/anionic vacancies or anti-site defects. Comparison with the other rare earth perovskites leads to the empirical rule that the magnetic-field-sensitive transitions require planes of heavy elements (e.g. lanthanum) and oxygen without any other light cations in the same plane. These magnetic degrees of freedom in rare earth perovskites with useful dielectric properties may be tunable by appropriate defect engineering for magneto-optic applications.

  16. 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.

  17. Magnetic-field-induced dose effects in MR-guided radiotherapy systems: dependence on the magnetic field strength.

    Science.gov (United States)

    Raaijmakers, A J E; Raaymakers, B W; Lagendijk, J J W

    2008-02-21

    Several institutes are currently working on the development of a radiotherapy treatment system with online MR imaging (MRI) modality. The main difference between their designs is the magnetic field strength of the MRI system. While we have chosen a 1.5 Tesla (T) magnetic field strength, the Cross Cancer Institute in Edmonton will be using a 0.2 T MRI scanner and the company Viewray aims to use 0.3 T. The magnetic field strength will affect the severity of magnetic field dose effects, such as the electron return effect (ERE): considerable dose increase at tissue air boundaries due to returning electrons. This paper has investigated how the ERE dose increase depends on the magnetic field strength. Therefore, four situations where the ERE occurs have been simulated: ERE at the distal side of the beam, the lateral ERE, ERE in cylindrical air cavities and ERE in the lungs. The magnetic field comparison values were 0.2, 0.75, 1.5 and 3 T. Results show that, in general, magnetic field dose effects are reduced at lower magnetic field strengths. At the distal side, the ERE dose increase is largest for B = 0.75 T and depends on the irradiation field size for B = 0.2 T. The lateral ERE is strongest for B = 3 T but shows no effect for B = 0.2 T. Around cylindrical air cavities, dose inhomogeneities disappear if the radius of the cavity becomes small relative to the in-air radius of the secondary electron trajectories. At larger cavities (r > 1 cm), dose inhomogeneities exist for all magnetic field strengths. In water-lung-water phantoms, the ERE dose increase takes place at the water-lung transition and the dose decreases at the lung-water transition, but these effects are minimal for B = 0.2 T. These results will contribute to evaluating the trade-off between magnetic field dose effects and image quality of MR-guided radiotherapy systems.

  18. Geochemical normalization of magnetic susceptibility - a simple tool for distinction the sediment provenance and post-depositional processes in floodplain sediments

    Science.gov (United States)

    Famera, Martin; Matys Grygar, Tomas; Elznicova, Jitka

    2017-04-01

    Magnetic susceptibility is highly appreciated in sedimentary and environmental geology. It may also reflect provenance of the sediment and post-depositional changes therein, including soil-forming processes. We studied the applicability of Fe-normalization of mass-specific magnetic susceptibility (MS) and Ti-normalization of Fe concentrations in description of fluvial sediments from five different catchments. We dealt with two catchments with some "mafic" source rocks (Fe-rich rocks) and three almost purely "felsic" catchments (source rocks with dominant quartz and feldspars). The fine-grained floodplain sediments (from clayey silts to fine sands) were obtained by drill coring and analysed for Fe and Ti concentrations using X-ray fluorescence spectroscopy (EDXRF) and MS using kappabridge. To correct MS for the sedimentological grain-size effects and possible magnetic enrichment, we used background functions constructed in the same way like for heavy metals. The representative profiles downward the floodplain sediments demonstrate the following MS stratigraphy: (1) 15-50 cm thick top stratum A, usually with MS and heavy metal enrichment, (2) underlying stratum B with stable values of MS, MS/Fe and Fe/Ti and (3) the lowermost stratum C with variable Fe concentrations and MS and high-chroma reductimorphic features due to micro-accumulations of Fe and Mn oxides in discoloured matrix, or grey colour due to permanently removed Fe(III) oxide pigment. The boundary between strata B and C can be at a depth of several decimetres to more than 1 metre depending on the thickness of floodplain fines, site-specific river incision and water table fluctuation. For the construction of MS background functions we used Fe concentrations as an independent variable (a predictor). It allows for calculation of MS of sediments as it would not be affected by post-depositional changes and pollution. Pristine MS is than predicted for any sample using formula MS_PRISTINE = const·cFe + const

  19. The emergence of age-dependent social cognitive deficits after generalized insult to the developing brain: a longitudinal prospective analysis using susceptibility-weighted imaging.

    Science.gov (United States)

    Ryan, Nicholas P; Catroppa, Cathy; Cooper, Janine M; Beare, Richard; Ditchfield, Michael; Coleman, Lee; Silk, Timothy; Crossley, Louise; Beauchamp, Miriam H; Anderson, Vicki A

    2015-05-01

    Childhood and adolescence are critical periods for maturation of neurobiological processes that underlie complex social and emotional behavior including Theory of Mind (ToM). While structural correlates of ToM are well described in adults, less is known about the anatomical regions subsuming these skills in the developing brain or the impact of cerebral insult on the acquisition and establishment of high-level social cognitive skills. This study aimed to examine the differential influence of age-at-insult and brain pathology on ToM in a sample of children and adolescents with traumatic brain injury (TBI). Children and adolescents with TBI (n = 112) were categorized according to timing of brain insult: (i) middle childhood (5-9 years; n = 41); (ii) late childhood (10-11 years; n = 39); and (iii) adolescence (12-15 years; n = 32) and group-matched for age, gender, and socioeconomic status to a typically developing (TD) control group (n = 43). Participants underwent magnetic resonance imaging including a susceptibility-weighted imaging (SWI) sequence 2-8 weeks postinjury and were assessed on a battery of ToM tasks at 6- and 24-months after injury. Results showed that for adolescents with TBI, social cognitive dysfunction at 6- and 24-months postinjury was associated with diffuse neuropathology and a greater number of lesions detected using SWI. In the late childhood TBI group, we found a time-dependent emergence of social cognitive impairment, linked to diffuse neuropathology. The middle childhood TBI group demonstrated performance unrelated to SWI pathology and comparable to TD controls. Findings indicate that the full extent of social cognitive deficits may not be realized until the associated skills reach maturity. Evidence for brain structure-function relationships suggests that the integrity of an anatomically distributed network of brain regions and their connections is necessary for the acquisition and establishment of high-level social

  20. Magnetic Rotational Spectroscopy with Nanorods to Probe Time-Dependent Rheology of Microdroplets (Postprint)

    Science.gov (United States)

    2012-05-10

    Rheology of polymer solutions/ gels (e.g., hazardous fluids containing thickeners) and biofluids depends on the concen- tration, level of cross-linking...AFRL-RX-TY-TP-2012-0041 MAGNETIC ROTATIONAL SPECTROSCOPY WITH NANORODS TO PROBE TIME-DEPENDENT RHEOLOGY OF MICRODROPLETS (POSTPRINT...Rotational Spectroscopy with Nanorods to Probe Time- Dependent Rheology of Microdroplets (POSTPRINT) FA8650-09-D-5900-0002 QL102011 *Tokarev

  1. Magnetic Anisotropic Susceptibility Studies on Impact Structures in the Serra Geral Basalt, Paraná Basin, Brazil

    Science.gov (United States)

    Crosta, A. P.; MacDonald, W. D.

    2009-12-01

    Studies of magnetic properties of shocked basalt are underway for two impact craters in the 132 Ma Serra Geral basalt of southern Brazil: the Vista Alegre crater (25.95°S, 41.69°W) in the state of Paraná, with a diameter of 12.4 km, and the Vargeão crater (26.81°S, 52.17°W) in Santa Catarina, of 9.5 km. Shatter cones and quartz planar deformation features (pdfs) have been found at both structures. Uplifted crater rims and external ejecta deposits have been removed by erosion at both craters. The interior of the Vista Alegre crater contains ejecta fallback deposits, typically reworked and weathered, and basalts of the crater floor are poorly exposed. In contrast, shocked basalts are exposed across the interior of the Vargeão structure, ejecta fallback deposits have been removed by erosion, and a central domal uplift of quartzose strata from beneath the basalt is found. Discounting the possibility of differential erosion rates, these differences might suggest that the Vargeão is the older of the two structures. Laboratory experiments elsewhere have suggested that major axes of the ellipse of anisotropic susceptibility (K1 major; K3 minor) could be aligned with the direction of propagation of the shockwave accompanying impact processes. Insufficient exposures exist at Vista Alegre to test this hypothesis. Oriented samples along a NNW-trending diametral profile across the better exposed Vargeão structure did not show a radial alignment of either K1 or K3 relative to the centre of that structure. In general, the mean susceptibility at Vargeão is lower towards the center; the degree of anisotropy is low (Pj<1.01), and the highest degree of anisotropy is in basalts adjacent to the central uplift. The shape factor (T) varies considerably (-0.5 (prolate) to +0.7 (oblate)); most magnetofabrics are oblate. Only 3 of 16 sites are prolate, and those are near the crater margin. K3 (minimum) axes are mainly steep, with a mean direction steep and slightly north of the

  2. Translation balance for measuring magnetic susceptibilities at high or low temperatures (1962); Balance de translation pour la mesure des susceptibilites magnetiques a haute ou basse temperature (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Blaise, A.; Peuch, M.A. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1962-07-01

    A translation balance is described for the measurement of the magnetic susceptibilities of liquids or solids in the temperature range from 1.7 to 1400 deg. K. Measurements are made within a magnetic field adjustable from 3400 to 16000 oersteds, in any desired atmosphere. Susceptibilities between 10{sup -8} and 10{sup -4} u.e.m. C.G.S., can be measured. (authors) [French] La balance de translation decrite ici permet la mesure des susceptibilites magnetiques des liquides ou des solides dans la gamme de temperature allant de 1,7 a 1400 deg. K. Les mesures sont effectuees dans un champ magnetique ajustable de 3400 a 16000 oersteds, sous atmosphere controlee. La gamme des mesures de susceptibilite s'etend de 10{sup -8} a 10{sup -4} u.e.m. C.G.S. (auteurs)

  3. Magnetic-field and temperature dependence of the energy gap in InN nanobelt

    Directory of Open Access Journals (Sweden)

    K. Aravind

    2012-03-01

    Full Text Available We present tunneling measurements on an InN nanobelt which shows signatures of superconductivity. Superconducting transition takes place at temperature of 1.3K and the critical magnetic field is measured to be about 5.5kGs. The energy gap extrapolated to absolute temperature is about 110μeV. As the magnetic field is decreased to cross the critical magnetic field, the device shows a huge zero-bias magnetoresistance ratio of about 400%. This is attributed to the suppression of quasiparticle subgap tunneling in the presence of superconductivity. The measured magnetic-field and temperature dependence of the superconducting gap agree well with the reported dependences for conventional metallic superconductors.

  4. The magnetic retina: light-dependent and trigeminal magnetoreception in migratory birds.

    Science.gov (United States)

    Mouritsen, Henrik; Hore, P J

    2012-04-01

    Recent advances have brought much new insight into the physiological mechanisms and required characteristics of the sensory molecules that enable birds to use magnetic fields for orientation. European robins almost certainly have two magnetodetection senses, one associated with the ophthalmic branch of the trigeminal nerve, and one based on light-dependent radical-pair processes in both eyes. The first brain areas processing magnetic information from each of these two senses have been identified. It has been experimentally verified that Earth-strength magnetic fields can affect photo-induced chemical reactions and that these reactions can respond to magnetic field direction. Diagnostic behavioural experiments have provided clues to identify putative magnetoreceptive molecules in the retina. We discuss the implications of these and other recent findings and outline crucial open questions with an emphasis on the light-dependent mechanism.

  5. Temperature and bias voltage dependence of Co/Pd multilayer-based magnetic tunnel junctions with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Kugler, Zoe, E-mail: zkugler@physik.uni-bielefeld.d [Bielefeld University, Department of Physics, Universitaetsstr. 25, 33615 Bielefeld (Germany); Drewello, Volker; Schaefers, Markus; Schmalhorst, Jan; Reiss, Guenter; Thomas, Andy [Bielefeld University, Department of Physics, Universitaetsstr. 25, 33615 Bielefeld (Germany)

    2011-01-15

    Temperature- and bias voltage-dependent transport measurements of magnetic tunnel junctions (MTJs) with perpendicularly magnetized Co/Pd electrodes are presented. Magnetization measurements of the Co/Pd multilayers are performed to characterize the electrodes. The effects of the Co layer thickness in the Co/Pd bilayers, the annealing temperature, the Co thickness at the MgO barrier interface, and the number of bilayers on the tunneling magneto resistance (TMR) effect are investigated. TMR-ratios of about 11% at room temperature and 18.5% at 13 K are measured and two well-defined switching fields are observed. The results are compared to measurements of MTJs with Co-Fe-B electrodes and in-plane anisotropy.

  6. A record of Quaternary humidity fluctuations on the NE Tibetan Plateau based on magnetic susceptibility variations in lacustrine sediments of the Qaidam Basin

    Science.gov (United States)

    Herb, Christian; Koutsodendris, Andreas; Zhang, Weilin; Appel, Erwin; Pross, Jörg; Fang, Xiaomin

    2013-04-01

    Magnetic susceptibility (?) and other magnetic proxies play an important role in paleoclimatic studies as they hold the potential for high-resolution records of past environmental change. Nevertheless, it is necessary to understand the cause of the variation in magnetic proxies by comparing them to more direct climate proxies such as pollen or stable isotopes. In this study we have compiled a high-resolution magnetic proxy dataset of the ca. 940-m-long core SG-1, which was drilled in the lacustrine sediments of the western Qaidam Basin on the northeastern Tibetan Plateau. Our record spans the entire Quaternary (~2.8 to 0.1 Ma). The magnetic susceptibility record is compared to the Artemisia/Chenopodiaceae (A/C) ratio, which is used to discriminate between dry and more humid phases in the Qaidam Basin, based on (i) 41 samples spanning the Middle Pleistocene Transition (MPT; ~1 Ma BP) and (ii) additional 40 samples selected from intervals of minimum and maximum ? values throughout the core. For the drill core SG-1, we observe a high correlation of the A/C ratio with ? results: minima of ? correspond to maxima of the A/C ratio (representing more humid phases) and vice versa. Additionally, spectral analysis of the ? record shows the emergence of the 100-ka Milankovitch cycle after the MPT. This testifies to the fact that cyclic variation of ? represents a response to global climate change.

  7. Magnetic state dependent transient lateral photovoltaic effect in patterned ferromagnetic metal-oxide-semiconductor films

    Directory of Open Access Journals (Sweden)

    Isidoro Martinez

    2015-11-01

    Full Text Available We investigate the influence of an external magnetic field on the magnitude and dephasing of the transient lateral photovoltaic effect (T-LPE in lithographically patterned Co lines of widths of a few microns grown over naturally passivated p-type Si(100. The T-LPE peak-to-peak magnitude and dephasing, measured by lock-in or through the characteristic time of laser OFF exponential relaxation, exhibit a notable influence of the magnetization direction of the ferromagnetic overlayer. We show experimentally and by numerical simulations that the T-LPE magnitude is determined by the Co anisotropic magnetoresistance. On the other hand, the magnetic field dependence of the dephasing could be described by the influence of the Lorentz force acting perpendiculary to both the Co magnetization and the photocarrier drift directions. Our findings could stimulate the development of fast position sensitive detectors with magnetically tuned magnitude and phase responses.

  8. Magnetization reversal in a site-dependent anisotropic Heisenberg ferromagnet under electromagnetic wave propagation

    Directory of Open Access Journals (Sweden)

    L. Kavitha

    2016-02-01

    Full Text Available Information density and switching of magnetization offers an interesting physical phenomenon which invoke magneto-optical techniques employed on the magnetic medium. In this paper, we explore the soliton assisted magnetization reversal in the nanosecond regime in the theoretical framework of the Landau–Lifshitz–Maxwell (LLM model. Starting from the Landau–Lifshitz equation, we employ the reductive perturbation method to derive an inhomogeneous nonlinear Schrödinger equation, governing the nonlinear spin excitations of a site-dependent anisotropic ferromagnetic medium under the influence of electromagnetic (EM field in the classical continuum limit. From the results, it is found that the soliton undergoes a flipping thereby indicating the occurrence of magnetization reversal behavior in the nanoscale regime due to the presence of inhomogeneity in the form of a linear function. Besides, the spin components of magnetization are also evolved as soliton spin excitations.

  9. Gravitational Waves from Pulsars and Their Braking Indices: The Role of a Time Dependent Magnetic Ellipticity

    CERN Document Server

    de Araujo, José C N; Costa, César A

    2016-01-01

    We study the role of time dependent magnetic ellipticities ($\\epsilon_{B}$) on the calculation of the braking index of pulsars. Moreover, we study the consequences of such a $\\epsilon_{B}$ on the amplitude of gravitational waves (GWs) generated by pulsars with measured braking indices. We show that, since the ellipticity generated by the magnetic dipole is extremely small, the corresponding amplitude of GWs is much smaller than the amplitude obtained via the spindown limit.

  10. Doping-dependent magnetization plateaus of a coupled spin-electron chain: exact results

    Science.gov (United States)

    Strečka, Jozef; Čisárová, Jana

    2016-10-01

    A coupled spin-electron chain composed of localized Ising spins and mobile electrons is exactly solved in an external magnetic field within the transfer-matrix method. The ground-state phase diagram involves in total seven different ground states, which differ in the number of mobile electrons per unit cell and the respective spin arrangements. A rigorous analysis of the low-temperature magnetization process reveals doping-dependent magnetization plateaus, which may be tuned through the density of mobile electrons. It is demonstrated that the fractional value of the electron density is responsible for an enhanced magnetocaloric effect due to an annealed bond disorder of the mobile electrons.

  11. Magnetic field dependence of the threshold electric field in unconventional charge density waves

    Science.gov (United States)

    Dóra, Balázs; Virosztek, Attila; Maki, Kazumi

    2002-04-01

    Many experiments suggest that the unidentified low-temperature phase of α-(BEDT-TTF)2KHg(SCN)4 is most likely unconventional charge density wave (UCDW). To further extend this identification we present our theoretical study of the threshold electric field of UCDW in a magnetic field. The magnetic field-temperature phase diagram is very similar to those in a d-wave superconductor. The optical conductivity shows clear features characteristic to both UDW and magnetic field. We find a rather strong field dependence of the threshold electric field, which shows qualitatively good agreement with the experimental data.

  12. Magnetization-dependent viscosity in brute-force-polarized liquid 3He

    DEFF Research Database (Denmark)

    Vermeulen, G.A.; Schuhl, A.; Joffrin, J.

    1988-01-01

    A new method to measure the magnetization dependence of the viscosity in polarized liquid He3 is presented. The magnetization is obtained by "brute-force polarization" at 45 mK in magnetic fields up to 11 T; it is subsequently destroyed by saturation of the NMR signal. Our result, a relative...... increase of the viscosity of (31.5)×10-3 at 3.9% polarization and a pressure of 30 bars, disagrees with a prediction based on the "nearly metamagnetic" model....

  13. Using magnetic susceptibility to facilitate more rapid, reproducible and precise delineation of hydric soils in the midwestern USA

    Science.gov (United States)

    Grimley, D.A.; Arruda, N.K.; Bramstedt, M.W.

    2004-01-01

    Standard field indicators, currently used for hydric soil delineations [USDA-NRCS, 1998. Field indicators of hydric soils in the United States, Version 4.0. In: G.W. Hurt et al. (Ed.), United States Department of Agriculture-NRCS, Fort Worth, TX], are useful, but in some cases, they can be subjective, difficult to recognize, or time consuming to assess. Magnetic susceptibility (MS) measurements, acquired rapidly in the field with a portable meter, have great potential to help soil scientists delineate and map areas of hydric soils more precisely and objectively. At five sites in Illinois (from 5 to 15 ha in area) with contrasting soil types and glacial histories, the MS values of surface soils were measured along transects, and afterwards mapped and contoured. The MS values were found to be consistently higher in well-drained soils and lower in hydric soils, reflecting anaerobic deterioration of both detrital magnetite and soil-formed ferrimagnetics. At each site, volumetric MS values were statistically compared to field indicators to determine a critical MS value for hydric soil delineation. Such critical values range between 22??10-5 and 33??10-5 SI in silty loessal or alluvial soils in Illinois, but are as high as 61??10-5 SI at a site with fine sandy soil. A higher magnetite content and slower dissolution rate in sandy soils may explain the difference. Among sites with silty parent material, the lowest critical value (22??10-5 SI) occurs in soil with low pH (4.5-5.5) since acidic conditions are less favorable to ferrimagnetic mineral neoformation and enhance magnetite dissolution. Because of their sensitivity to parent material properties and soil pH, critical MS values must be determined on a site specific basis. The MS of studied soil samples (0-5 cm depth) is mainly controlled by neoformed ultrafine ferrimagnetics and detrital magnetite concentrations, with a minor contribution from anthropogenic fly ash. Neoformed ferrimagnetics are present in all samples

  14. Light-dependent magnetic compass orientation in amphibians and insects: candidate receptors and candidate molecular mechanisms

    Science.gov (United States)

    Phillips, John B.; Jorge, Paulo E.; Muheim, Rachel

    2010-01-01

    Magnetic compass orientation by amphibians, and some insects, is mediated by a light-dependent magnetoreception mechanism. Cryptochrome photopigments, best known for their role in circadian rhythms, are proposed to mediate such responses. In this paper, we explore light-dependent properties of magnetic sensing at three levels: (i) behavioural (wavelength-dependent effects of light on magnetic compass orientation), (ii) physiological (photoreceptors/photopigment systems with properties suggesting a role in magnetoreception), and (iii) molecular (cryptochrome-based and non-cryptochrome-based signalling pathways that are compatible with behavioural responses). Our goal is to identify photoreceptors and signalling pathways that are likely to play a specialized role in magnetoreception in order to definitively answer the question of whether the effects of light on magnetic compass orientation are mediated by a light-dependent magnetoreception mechanism, or instead are due to input from a non-light-dependent (e.g. magnetite-based) magnetoreception mechanism that secondarily interacts with other light-dependent processes. PMID:20124357

  15. Vector spin modeling for magnetic tunnel junctions with voltage dependent effects

    Energy Technology Data Exchange (ETDEWEB)

    Manipatruni, Sasikanth, E-mail: sasikanth.manipatruni@intel.com; Nikonov, Dmitri E.; Young, Ian A. [Exploratory Integrated Circuits, Components Research, Intel Corp., Hillsboro, Oregon 97124 (United States)

    2014-05-07

    Integration and co-design of CMOS and spin transfer devices requires accurate vector spin conduction modeling of magnetic tunnel junction (MTJ) devices. A physically realistic model of the MTJ should comprehend the spin torque dynamics of nanomagnet interacting with an injected vector spin current and the voltage dependent spin torque. Vector spin modeling allows for calculation of 3 component spin currents and potentials along with the charge currents/potentials in non-collinear magnetic systems. Here, we show 4-component vector spin conduction modeling of magnetic tunnel junction devices coupled with spin transfer torque in the nanomagnet. Nanomagnet dynamics, voltage dependent spin transport, and thermal noise are comprehended in a self-consistent fashion. We show comparison of the model with experimental magnetoresistance (MR) of MTJs and voltage degradation of MR with voltage. Proposed model enables MTJ circuit design that comprehends voltage dependent spin torque effects, switching error rates, spin degradation, and back hopping effects.

  16. The Effect Of A Magnetic Field Dependent Viscosity On The Thermal Convection In A Ferromagnetic Fluid In A Porous Medium

    National Research Council Canada - National Science Library

    Sunil; Pavan Kumar Bharti; Divya Sharma; R. C. Sharma

    2004-01-01

    The effect of the magnetic field dependent (MFD) viscosity on the thermal convection in a ferromagnetic fluid in the presence of a uniform vertical magnetic field is considered for a fluid layer in a porous medium, heated from below...

  17. Time-Transgressive Nature of the Magnetic Susceptibility Record across the Chinese Loess Plateau at the Pleistocene/Holocene Transition.

    Directory of Open Access Journals (Sweden)

    Yajie Dong

    Full Text Available The loess stratigraphic boundary at the Pleistocene/Holocene transition defined by the magnetic susceptibility (MS has previously been assumed to be synchronous with the Marine Isotope Stage (MIS 2/1 boundary, and approximately time-synchronous at different sections across the Chinese Loess Plateau (CLP. However, although this assumption has been used as a basis for proxy-age model of Chinese loess deposits, it has rarely been tested by using absolute dating methods. In this study, we applied a single-aliquot regenerative-dose (SAR protocol to the 45-63 μm quartz grain-size fraction to derive luminescence ages for the last glacial and Holocene sections of three loess sections on a transect from southeast to northwest across the CLP. Based on the 33 closely spaced optically stimulated luminescence (OSL samples from the three sections, OSL chronologies were established using a polynomial curve fit at each section. Based on the OSL chronology, the timing of the Pleistocene/Holocene boundary, as defined by rapid changes in MS values, is dated at ~10.5 ka, 8.5 ka and 7.5 ka in the Yaoxian section, Jingchuan and Huanxian sections respectively. These results are clearly inconsistent with the MIS 2/1 boundary age of 12.05 ka, and therefore we conclude that the automatic correlation of the Pleistocene/Holocene transition, as inferred from the MS record, with the MIS 2/1 boundary is incorrect. The results clearly demonstrate that the marked changes in MS along the southeast to northwest transect are time-transgressive among the different sites, with the timing of significant paleosol development as indicated by the MS record being delayed by 3-4 ka in the northwest compared to the southeast. Our results suggest that this asynchronous paleosol development during the last deglacial was caused by the delayed arrival of the summer monsoon in the northwest CLP compared to the southeast.

  18. Thermal relaxation of magnetic clusters in amorphous Hf_{57}Fe_{43} alloy

    OpenAIRE

    Pajic, Damir; Zadro, Kreso; Ristic, Ramir; Zivkovic, Ivica; Skoko, Zeljko; Babic, Emil

    2006-01-01

    The magnetization processes in binary magnetic/nonmagnetic amorphous alloy Hf_{57}Fe_{43} are investigated by the detailed measurements of magnetic hysteresis loops, temperature dependence of magnetization, relaxation of magnetization and magnetic ac susceptibility, including a nonlinear term. Blocking of magnetic moments at lower temperatures is accompanied with the slow relaxation of magnetization and magnetic hysteresis loops. All of the observed properties are explained with the superpara...

  19. Temperature dependence of magnetically induced deformation of Ni-Mn-Ga martensite

    Science.gov (United States)

    L'Vov, V. A.; Glavatska, N.; Aaltio, I.; Söderberg, O.; Glavatskiy, I.; Hannula, S.-P.

    2008-05-01

    In the present work the contributions of the temperature-dependent (i) crystal lattice parameters (related to the magnetic anisotropy energy), (ii) Young's modulus, (iii) saturation magnetization and (iv) thermal fluctuations of the microstress to the temperature dependence of the magnetic field induced strain (MFIS) in Ni-Mn-Ga martensite are considered in the framework of a statistical model. Both individual and cooperative effects of these factors on the achievable MFIS value and on the characteristic values of the magnetic fields, which trigger and saturate MFIS, are estimated. It is shown that all the factors affect both the achievable MFIS value and characteristic fields under the real experimental conditions, and none of them can be neglected in the quantitative theoretical analysis of the experimental strain-field dependencies obtained for different temperature values. In addition, the influence of specimen shape on the characteristic fields is illustrated for different temperature values. For the available experimental dependencies (i) (iii) and the reasonable set of model parameters the switching magnetic field proved to be equal to 160 kA/m when the temperature was by 15 K below the martensite start temperature and raised to 320 kA/m when the temperature was by 45 K below the martensite start temperature. Obtained results agree with the experimental data reported by O. Heczko and L. Straka, in J. Appl. Phys. 94, 7139 (2003).

  20. Resonance dependence of gravitropicreactionof cress roots in weak combined magnetic fields.

    Science.gov (United States)

    Bogatina, N. I.; Sheykina, N. V.; Kordyum, E. L.

    The gravitropic reaction of cress was studied in combined magnetic fields, that is the static magnetic field of the order of Earth's one and parallel to it alternating magnetic field. The frequency region for alternating magnetic field was varied in wide diapason ( from 1 Hz up to 45 Hz). The magnitude of alternating magnetic field was equal to 6 microT. The magnetic field conditions were well reproducible. For this purpose the external magnetic field was shielded in the work volume and artificial magnetic field was created in the volume. Both ferromagnetic metal shield and superconductive one with warm volume for work were used. The magnetic noises inside both of ferromagnetic metal and superconductive shields were measured to provide the well reproducible characteristics of artificial field created in the work volume. The objects of investigation were the roots of cress after 2-3-days germination. They were located in the closed humid room, that was located inside the shield in the artificially created magnetic field. All roots were in the darkness. For control we used the analogous roots located in the analogous volume but only in the static magnetic field of the Earth. We measured the divergence angle of the root from its primary direction of growing. We obtained the following results. The curve of dependence of measured angles on the frequency of alternating component of magnetic field had series of sharp peaks. These peaks were well reproducible and their location depended on the magnitude of the static component of magnetic field. The frequency of peak location is in direct proportion with its magnitude. The analysis showed that the location of peaks coincided very well with the cyclotron frequencies of the following ions: Ca+2, Cu+1 , K+1: Fe+3: Ag+1: and with the cyclotron frequencies of ions of phytohormons such as ions of indolile-acetic acid, abscise acid and gibberellins. Some quantitive analogies between the gravitropic process and the effect of

  1. Time-dependent Suppression of Oscillatory Power in Evolving Solar Magnetic Fields

    Science.gov (United States)

    Krishna Prasad, S.; Jess, D. B.; Jain, R.; Keys, P. H.

    2016-05-01

    Oscillation amplitudes are generally smaller within magnetically active regions like sunspots and plage when compared to their surroundings. Such magnetic features, when viewed in spatially resolved power maps, appear as regions of suppressed power due to reductions in the oscillation amplitudes. Employing high spatial- and temporal-resolution observations from the Dunn Solar Telescope (DST) in New Mexico, we study the power suppression in a region of evolving magnetic fields adjacent to a pore. By utilizing wavelet analysis, we study for the first time how the oscillatory properties in this region change as the magnetic field evolves with time. Image sequences taken in the blue continuum, G-band, Ca ii K, and Hα filters were used in this study. It is observed that the suppression found in the chromosphere occupies a relatively larger area, confirming previous findings. Also, the suppression is extended to structures directly connected to the magnetic region, and is found to get enhanced as the magnetic field strength increased with time. The dependence of the suppression on the magnetic field strength is greater at longer periods and higher formation heights. Furthermore, the dominant periodicity in the chromosphere was found to be anti-correlated with increases in the magnetic field strength.

  2. Engineered materials for all-optical helicity-dependent magnetic switching

    Science.gov (United States)

    Mangin, S.; Gottwald, M.; Lambert, C.-H.; Steil, D.; Uhlíř, V.; Pang, L.; Hehn, M.; Alebrand, S.; Cinchetti, M.; Malinowski, G.; Fainman, Y.; Aeschlimann, M.; Fullerton, E. E.

    2014-03-01

    The possibility of manipulating magnetic systems without applied magnetic fields have attracted growing attention over the past fifteen years. The low-power manipulation of the magnetization, preferably at ultrashort timescales, has become a fundamental challenge with implications for future magnetic information memory and storage technologies. Here we explore the optical manipulation of the magnetization in engineered magnetic materials. We demonstrate that all-optical helicity-dependent switching (AO-HDS) can be observed not only in selected rare earth-transition metal (RE-TM) alloy films but also in a much broader variety of materials, including RE-TM alloys, multilayers and heterostructures. We further show that RE-free Co-Ir-based synthetic ferrimagnetic heterostructures designed to mimic the magnetic properties of RE-TM alloys also exhibit AO-HDS. These results challenge present theories of AO-HDS and provide a pathway to engineering materials for future applications based on all-optical control of magnetic order.

  3. Influence of anisotropy of magnetic susceptibility (AMS) on paleomagnetic sampling in volcanic glasses: a case study on rheomorphic ignimbrites of the Yellowstone hotspot-track, southern Idaho

    Science.gov (United States)

    Finn, D.; Coe, R. S.; Murphy, J.; Bodiford, S.; Kelly, H.; Foster, S.; Spinardi, F.; Reichow, M. K.; Knott, T.; Branney, M. J.

    2012-12-01

    Large-scale explosive volcanism, associated with the Yellowstone hotspot, occurred in the central Snake River Plain between 12.5-8 Ma. It is characterized by unusually high-temperature, intensely welded, rheomorphic rhyolitic ignimbrites, typical of what is now known as 'Snake River (SR)-type volcanism'. Individual eruption volumes likely exceed 450 km3 but are poorly known due to the difficulty of correlating units between widely spaced (50-200 km) exposures along the north and south of the plain, when some occurred too close-spaced in time for radiometric resolution. Our goal is to use a combination of paleomagnetic, petrographic, chemical and field characterization to establish robust correlations, allowing us to develop a regional stratigraphy, and constrain ignimbrite eruption volumes and frequencies. This presentation focuses on how to sample rheomorphic, SR-type ignimbrites for paleomagnetic studies given the potential effects of hot, rheomorphic deformation. Individual SR-type ignimbrite cooling-units have an upper and lower glassy margins (vitrophyre) enclosing a lithoidal (microcrystalline) zone. We have sampled dozens of ignimbrites in detail and have observed that the lithoidal interiors are preferable to the glassy margins for paleomagnetic studies. We hypothesize that the glassy margins retain an anisotropic fabric related to emplacement compaction and/or shearing that affects their ability to accurately record the magnetic field during cooling. In the lithoidal interiors this anisotropic fabric was overprinted by continued grain growth and/or alteration and, therefore, may accurately record the paleomagnetic field. Paleomagnetic samples from vitrophyres generally have a higher anisotropy in magnetic susceptibility than lithoidal samples. The remanent magnetic directions recorded in samples with high anisotropy of magnetic susceptibility are often deflected away from the site mean and closer to the plane of easy magnetic susceptibility. Since the

  4. Nonlinear Temperature Dependence of Magnetization of Two-Band Superconductors Near Upper Critical Field

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Temperature dependence of the magnetization M(T) of two-band superconductors is studied in the vicinity of upper critical field Hc2 by using a two-band Ginzburg-Landau (GL) theory. It is shown that magnetization M(T) has a nonlinear character due to positive curvature of upper critical field Hc2(T) and temperature dependence of effective Ginzburg-Landau parameter (n)eff(T). The results are shown to be in qualitative agreement with experimental data for the superconducting magnesium diboride, MgB2.

  5. Magnetic field and temperature dependence of the critical vortex velocity in type-II superconducting films.

    Science.gov (United States)

    Grimaldi, G; Leo, A; Cirillo, C; Attanasio, C; Nigro, A; Pace, S

    2009-06-24

    We study the vortex dynamics in the instability regime induced by high dissipative states well above the critical current in Nb superconducting strips. The magnetic field and temperature behavior of the critical vortex velocity corresponding to the observed dynamic instability is ascribed to intrinsic non-equilibrium phenomena. The Larkin-Ovchinnikov (LO) theory of electronic instability in high velocity vortex motion has been applied to interpret the temperature dependence of the critical vortex velocity. The magnetic field dependence of the vortex critical velocity shows new features in the low-field regime not predicted by LO.

  6. Overcoming the concentration-dependence of responsive probes for magnetic resonance imaging

    Science.gov (United States)

    Ekanger, Levi A.

    2015-01-01

    In magnetic resonance imaging, contrast agents are molecules that increase the contrast-to-noise ratio of non-invasively acquired images. The information gained from magnetic resonance imaging can be increased using responsive contrast agents that undergo chemical changes, and consequently changes to contrast enhancement, for example in response to specific biomarkers that are indicative of diseases. A major limitation with modern responsive contrast agents is concentration-dependence that requires the concentration of contrast agent to be known: an extremely challenging task in vivo. Here, we review advances in several strategies aimed at overcoming the concentration-dependent nature of responsive contrast agents. PMID:25579206

  7. Magnetic field and temperature dependence of the critical vortex velocity in type-II superconducting films

    Energy Technology Data Exchange (ETDEWEB)

    Grimaldi, G; Leo, A; Cirillo, C; Attanasio, C; Nigro, A; Pace, S [CNR-INFM Laboratorio Regionale SuperMat, Via Salvador Allende, I-84081 Baronissi (Italy)], E-mail: grimaldi@sa.infn.it

    2009-06-24

    We study the vortex dynamics in the instability regime induced by high dissipative states well above the critical current in Nb superconducting strips. The magnetic field and temperature behavior of the critical vortex velocity corresponding to the observed dynamic instability is ascribed to intrinsic non-equilibrium phenomena. The Larkin-Ovchinnikov (LO) theory of electronic instability in high velocity vortex motion has been applied to interpret the temperature dependence of the critical vortex velocity. The magnetic field dependence of the vortex critical velocity shows new features in the low-field regime not predicted by LO.

  8. Gap-related trapped magnetic flux dependence between single and combined bulk superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Z., E-mail: zgdeng@gmail.co [Laboratory of Applied Physics, Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, Tokyo 135-8533 (Japan); Miki, M.; Felder, B.; Tsuzuki, K.; Shinohara, N.; Uetake, T.; Izumi, M. [Laboratory of Applied Physics, Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, Tokyo 135-8533 (Japan)

    2011-05-15

    Highlights: {yields} Rectangular YBCO bulks to realize a compact combination. {yields} The gap effect was added to consider in the trapped flux density mapping. {yields} The trapped-flux dependence between single and combined bulks is gap related. {yields} It is possible to estimate the total magnetic flux of bulk combinations. - Abstract: Aiming at examining the trapped-flux dependence between single and combined bulk superconductors for field-pole applications, three rectangular Y{sub 1.65}Ba{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) bulks with a possibly compact combination were employed to investigate the trapped-flux characteristics of single and combined bulks with a field-cooling magnetization (FCM) method. A gap-related dependence was found between them. At lower gaps of 1 mm and 5 mm, the peak trapped fields and total magnetic flux of combined bulks are both smaller than the additive values of each single bulk, which can be ascribed to the demagnetization influences of the field around the bulk generated by the adjacent ones. While, at larger gaps like 10 mm, the situation becomes reversed. The combined bulks can attain bigger peak trapped fields as well as total magnetic flux, which indicates that the magnetic field by the bulk combination can reach higher gaps, thanks to the bigger magnetic energy compared with the single bulk. The presented results show that, on one hand, it is possible to estimate the total trapped magnetic flux of combined bulks by an approximate additive method of each single bulk while considering a demagnetization factor; on the other hand, it also means that the performance of combined bulks will be superior to the addition of each single bulk at larger gaps, thus preferable for large-scaled magnet applications.

  9. History dependence of the magnetic properties of single-crystal Fe1 -xCoxSi

    Science.gov (United States)

    Bauer, A.; Garst, M.; Pfleiderer, C.

    2016-06-01

    We report the magnetization, ac susceptibility, and specific heat of optically float-zoned single crystals of Fe1 -xCoxSi , 0.20 ≤x ≤0.50 . We determine the magnetic phase diagrams for all major crystallographic directions and cooling histories. After zero-field cooling, the phase diagrams resemble that of the archetypal stoichiometric cubic chiral magnet MnSi. Besides the helical and conical state, we observe a pocket of skyrmion lattice phase just below the helimagnetic ordering temperature. At the phase boundaries between these states evidence for slow dynamics is observed. When the sample is cooled in small magnetic fields, the phase pocket of skyrmion lattice may persist metastably down to the lowest temperatures. Taken together with the large variation in the transition temperatures, transition fields, and helix wavelength as a function of the composition, this hysteresis identifies Fe1 -xCoxSi as an ideal material for future experiments exploring, for instance, the topological unwinding of the skyrmion lattice.

  10. Slow relaxation of the magnetization in an Isostructural series of Zinc-lanthanide complexes: an integrated EPR and AC susceptibility study

    Science.gov (United States)

    Amjad, Asma; Madalan, Augustin; Andruh, Marius; Caneschi, Andrea; Sorace, Lorenzo; University of Bucharest, Faculty of Chemistry, Inorganic Chemistry Laboratory, Bucharest, Romania Collaboration

    2015-03-01

    Lanthanide based molecular complexes have shown potential to behave as single molecule magnets proficient to function above cryogenic temperatures. In this work we explore the dynamics of one such family, [Zn(LH)2Ln](NO3)3 .6H2O - (Ln = Nd3+, Dy3+, Tb3+, Ho3+, Er3+, Yb3+) . The series has a single lanthanide ion as a magnetic center in a low symmetry environment; the dynamics and energy landscape of the series is explored using X-band EPR, AC and DC susceptibility over a range of temperature, field and frequency. DC magnetic data show χT value consistent with expected behavior. EPR spectra for Er3+ and Yb3+ complexes shows EPR spectra typical for easy-plane and quasi-isotropic systems respectively, thus explaining the lack of out of phase susceptibility even in an external applied filed. However, Dy3+ derivative show slow relaxation of the magnetization in zero field up to 15 K and is, accordingly EPR silent.

  11. T3SS-dependent differential modulations of the jasmonic acid pathway in susceptible and resistant genotypes of Malus spp. challenged with Erwinia amylovora.

    Science.gov (United States)

    Dugé De Bernonville, Thomas; Gaucher, Matthieu; Flors, Victor; Gaillard, Sylvain; Paulin, Jean-Pierre; Dat, James F; Brisset, Marie-Noëlle

    2012-06-01

    Fire blight is a bacterial disease of Maloideae caused by Erwinia amylovora (Ea). This necrogenic enterobacterium uses a type III secretion system (T3SS) to inject type III effectors into the plant cells to cause disease on its susceptible hosts, including economically important crops like apple and pear. The expressions of marker genes of the salicylic acid (SA) and jasmonic acid (JA) defense regulation pathways were monitored by RT-qPCR in leaves of two apple genotypes, one susceptible and one resistant, challenged with a wild type strain, a T3SS-deficient strain or water. The transcriptional data taken together with hormone level measurements indicated that the SA pathway was similarly induced in both apple genotypes during infection by Ea. On the contrary, the data clearly showed a strong T3SS-dependent down-regulation of the JA pathway in leaves of the susceptible genotype but not in those of the resistant one. Accordingly, methyl-jasmonate treated susceptible plants displayed an increased resistance to Ea. Bacterial mutant analysis indicated that JA manipulation by Ea mainly relies on the type III effector DspA/E. Taken together, our data suggest that the T3SS-dependent down-regulation of the JA pathway is a critical step in the infection process of Malus spp. by Ea.

  12. Multi-Sensor Core Logger (MSCL) P-wave velocity, gamma-ray density, and magnetic susceptibility whole-core logs of sediment cores collected in 2009 offshore from Palos Verdes, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of the data release includes Multi-Sensor Core Logger (MSCL) P-wave velocity, gamma-ray density, and magnetic susceptibility whole-core logs of sediment...

  13. Dependence of magnetization on crystal fields and exchange interactions in magnetite

    Energy Technology Data Exchange (ETDEWEB)

    Ouaissa, Mohamed, E-mail: m.ouaissa@yahoo.fr [Laboratoire de Génie Physique et Environnement, Faculté des Sciences, Université Ibn Tofail, Campus Universitaire BP 133, Kénitra 14000 (Morocco); Benyoussef, Abdelilah [Laboratory of Magnetism and Physics of High Energy, Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Abo, Gavin S. [Department of Electrical and Computer Engineering and MINT Center, The University of Alabama, Tuscaloosa, AL 35487 (United States); Ouaissa, Samia; Hafid, Mustapha [Laboratoire de Génie Physique et Environnement, Faculté des Sciences, Université Ibn Tofail, Campus Universitaire BP 133, Kénitra 14000 (Morocco); Belaiche, Mohammed [Laboratoire de Magnétisme, Matériaux Magnétiques, Microonde et Céramique, Ecole Normale Supérieure, Université Mohammed V-Agdal, B.P. 9235, Océan, Rabat (Morocco)

    2015-11-15

    In this work, we study the magnetization of magnetite (Fe{sub 3}O{sub 4}) with different exchange interactions and crystal fields using variational method based on the Bogoliubov inequality for the Gibbs free energy within the mean field theory. The magnetic behavior was investigated in the absence and presence of crystal fields. The investigations also revealed that the transition temperature depends on the crystal fields of the octahedral and tetrahedral sites. Magnetite exhibits ferrimagnetic phase with second order transition to paramagnetic phase at 850 K. This result is confirmed using the mean field theory within the Heisenberg model. Important factors that can affect the magnetic behavior of the system are exchange interactions and crystal field. Indeed, a new magnetic behavior was observed depending on these parameters. A first order phase transition from ferrimagnetic to ferromagnetic was found at low temperature, and a second order transition from ferromagnetic to paramagnetic was observed at high temperature. - Highlights: • Magnetization of magnetite versus temperature was studied by mean field theory. • The critical temperature of magnetite (Fe{sub 3}O{sub 4}) was approximately obtained. • Effect of sublattice crystal fields on the magnetization of Fe{sub 3}O{sub 4} was investigated.

  14. Layering and temperature-dependent magnetization and anisotropy of naturally produced Ni/NiO multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Pappas, S. D.; Trachylis, D.; Velgakis, M. J. [Laboratory of High-Tech Materials, School of Engineering, University of Patras, 26504 Patras (Greece); Kapaklis, V.; Joensson, P. E.; Papaioannou, E. Th. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Delimitis, A. [Chemical Process Engineering Research Institute (CPERI), Centre for Research and Technology Hellas (CERTH), 57001 Thermi, Thessaloniki (Greece); Poulopoulos, P. [Laboratory of High-Tech Materials, School of Engineering, University of Patras, 26504 Patras (Greece); Institut fuer Experimentalphysik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin-Dahlem (Germany); Materials Science Department, University of Patras, 26504 Patras (Greece); Fumagalli, P. [Institut fuer Experimentalphysik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin-Dahlem (Germany); Politis, C. [Laboratory of High-Tech Materials, School of Engineering, University of Patras, 26504 Patras (Greece); Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, Texas 76019 (United States)

    2012-09-01

    Ni/NiO multilayers were grown by magnetron sputtering at room temperature, with the aid of the natural oxidation procedure. That is, at the end of the deposition of each single Ni layer, air is let to flow into the vacuum chamber through a leak valve. Then, a very thin NiO layer ({approx}1.2 nm) is formed. Simulated x-ray reflectivity patterns reveal that layering is excellent for individual Ni-layer thickness larger than 2.5 nm, which is attributed to the intercalation of amorphous NiO between the polycrystalline Ni layers. The magnetization of the films, measured at temperatures 5-300 K, has almost bulk-like value, whereas the films exhibit a trend to perpendicular magnetic anisotropy (PMA) with an unusual significant positive interface anisotropy contribution, which presents a weak temperature dependence. The power-law behavior of the multilayers indicates a non-negligible contribution of higher order anisotropies in the uniaxial anisotropy. Bloch-law fittings for the temperature dependence of the magnetization in the spin-wave regime show that the magnetization in the multilayers decreases faster as a function of temperature than the one of bulk Ni. Finally, when the individual Ni-layer thickness decreases below 2 nm, the multilayer stacking vanishes, resulting in a dramatic decrease of the interface magnetic anisotropy and consequently in a decrease of the perpendicular magnetic anisotropy.

  15. Influence of time dependent longitudinal magnetic fields on the cooling process, exchange bias and magnetization reversal mechanism in FM core/AFM shell nanoparticles: a Monte Carlo study

    Science.gov (United States)

    Yüksel, Yusuf; Akıncı, Ümit

    2016-12-01

    Using Monte Carlo simulations, we have investigated the dynamic phase transition properties of magnetic nanoparticles with ferromagnetic core coated by an antiferromagnetic shell structure. Effects of field amplitude and frequency on the thermal dependence of magnetizations, magnetization reversal mechanisms during hysteresis cycles, as well as on the exchange bias and coercive fields have been examined, and the feasibility of applying dynamic magnetic fields on the particle have been discussed for technological and biomedical purposes.

  16. Spin interference in Rashba metal ring in a time-dependent magnetic field

    Science.gov (United States)

    Chen, Ji; Abdul Jalil, Mansoor Bin; Ghee Tan, Seng

    2013-05-01

    We investigate spin transport in a metal square ring with a strong Rashba spin orbit coupling (RSOC) effect, in the presence of a time-dependent magnetic field. We show that RSOC can be regarded as a spin-dependent gauge field which imparts a spin-dependent geometric phase (Aharonov-Casher phase) to conduction electrons in the ring. Combining the Aharonov-Bohm phase due to the time-dependent magnetic field with the able Aharonov-Casher phase due to RSOC, we are able to construct a spin interference condition, which modulates spin transport in the ring. The spin transport in the system is calculated via the tight-binding non-equilibrium Green's function formalism. Based on our transport calculations, we proposed a potential application of the Rashba square ring system as an alternating spin current generator.

  17. Azimuthal dependence of the Garton-Tomkins orbit in crossed magnetic and electric fields

    Science.gov (United States)

    Bleasdale, C.; Lewis, R. A.; Bruno-Alfonso, A.

    2016-08-01

    Work on classical closed orbits in the diamagnetic Kepler problem is predominately focused on the chaos observed in the polar launch angle as opposed to the azimuthal launch angle. This is due to atomic systems, along with widely studied external-field geometries (parallel magnetic and electric fields or pure magnetic field), being uniform in azimuthal angle, rendering the azimuthal angle unimportant. In the case of crossed magnetic and electric fields, this is no longer the case, and closed orbits do present an azimuthal launch angle dependence. In atomic systems, due to their spherical symmetry, the electric-field orientation in the plane perpendicular to the magnetic field does not affect the spectrum of orbits. However, in shallow n -type donors in anisotropic semiconductors such as silicon, the orientation of the external fields with respect to conduction-band valleys will be important. In this work we examine the Garton-Tomkins orbit in crossed magnetic and electric fields, and analyze how it and its harmonics' azimuthal dependencies behave through variation of the scaled field or scaled energy. At low scaled fields, harmonics have either twofold or fourfold azimuthal dependencies determined by the rotational symmetry of the individual harmonics. As the scaled field or scaled energy is increased, several harmonics undergo significant bifurcations, resulting in large azimuthal angular regions of essentially closed orbits, which will lead to strong resonances in experimental work.

  18. Method of magnetic susceptibility mapping of drilled cores. Experimental measurements for geologic structures determination; Methode de cartographie de susceptibilite magnetique sur carottes de forage. Mesures experimentales pour la determination de structures geologiques

    Energy Technology Data Exchange (ETDEWEB)

    Delrive, C.

    1993-11-08

    The evaluation of the safety of a deep geologic repository for dangerous materials requires the knowledge of the interstitial system of the surrounding host rock. A method is proposed for the determination of geologic structures (in particular fractures) from the magnetic susceptibility mapping of drilled cores. The feasibility of the method has been demonstrated using a SQUID magneto-gradient meter. A measurement tool using a new magnetic susceptibility captor and a testing bench have been developed. This tool allows the measurement of rocks with a magnetic susceptibility greater than 10{sup -5} SI units and can generate magnetic susceptibility maps with 4 x 4 mm{sup 2} pixels. A magnetic visibility criterion has been defined which allows to foresee if a structure is visible or not. According to the measurements done, it is shown that any centimeter-scale structure with a sufficient magnetic contrast (20%) with respect to the matrix is visible. Therefore, the dip and the orientation of such structure can be determined with a 3 degree and a 5 degree precision, respectively. The position of the structure along the core axis is known with a 4 mm precision. On the other hand, about half of the magnetic contrasts observed do not correspond to the visual analyses and can be explained by very small variations of the mineralogic composition. This last point offers some interesting ways for future research using magnetic susceptibility mapping. (J.S.). 31 refs., 90 figs., 18 tabs., 2 photos., 6 appends.

  19. Age dependent variation of magnetic fabric on dike swarms from Maio Island (Cape Verde)

    Science.gov (United States)

    Moreira, Mário; Madeira, José; Mata, João.; Represas, Patrícia

    2010-05-01

    Maio is one of the oldest and most eroded islands of Cape Verde Archipelago. It comprises three major geological units: (1) an old raised sea-floor sequence of MORB covered by Jurassic(?)-Cretaceous deep marine sediments; (2) an intrusive 'Central Igneous Complex' (CIC), forming a dome-like structure in the older rocks; and (3) a sequence of initially submarine, then subaerial, extrusive volcanic formations and sediments. Based on the trend distribution of 290 dikes, we performed magnetic sampling on 26 basic and one carbonatite dikes. Anisotropy of magnetic susceptibility (AMS) was measured to infer geometries of magmatic flow. Dikes were sampled in both chilled margins were larger shear acting on particles embedded in the magmatic flow is expected. Sampling involved 11 dikes (N=195) intruding MORB pillows from the Upper Jurassic 'Batalha Formation' (Bt fm); 6 dikes (N=95) intruding the Lower Cretaceous 'Carquejo Formation' (Cq fm), and 10 dikes (N=129) intruding the submarine sequence of the Neogene 'Casas Velhas Formation' (CV fm). The studied hypabissal rocks are usually porphyritic, with phenocrysts of clinopyroxene and/or olivine set on an aphanitic groundmass. Dikes intruding CV fm trend N-S to NE-SW and plunge to SW. In Bt fm, dikes make ≈ 99% of the outcrops, span all directions and include frequent low dip sills. Dikes intruding Cq fm are shallow (mostly parallel to the limestone strata), dip 30o- 40o to the E, and trend N-S to NE-SW. Bulk susceptibility of the 26 basic dikes presents an average value of k = 47 ± 26 (×10-3) SI. The carbonatite dike intruding Bt fm has lower susceptibility: k = 4.6 ± 1.2 (×10-3) SI. More than 80% of the dikes show normal and triaxial magnetic fabric. Anisotropy is usually low, with P' < 1.08, but in CV fm dikes the anisotropy is higher and grows (up to P' ≈ 1.5) towards the centre of the volcano. Dominant magnetic fabric in CV fm is planar but in dikes from Cq fm and Bt fm it varies between oblate and prolate

  20. Zero-field NMR of nematic liquid crystals with positive and negative magnetic susceptibility anisotropies. [Propyl-, pentyl-, and heptylbicyclo-hexylcarbonitriles, p-ethoxybenzylidene-p-butylaniline (EBBA)

    Energy Technology Data Exchange (ETDEWEB)

    Thayer, A.M.; Luzar, M.; Pines, A.

    1987-04-09

    Nematic liquid crystal systems with positive and negative magnetic susceptibility anisotropies are studied by NMR in high and zero magnetic fields. The behavior of the system in zero field is dictated by the form of the zero-field Hamiltonian, the symmetry of the liquid crystal phase, and the initial state of the magnetization. Zero-field evolution is initiated both with and without the use of dc pulsed fields in the field cycle. Pulsed dc fields are also used to remove the effects of residual field inhomogeneities by zero-field spin echoes. The order parameters measured in an applied field and in the absence of a field are found to be the same within experimental error for both types of liquid crystal.

  1. On the effect of time-dependent inhomogeneous magnetic fields in electron–positron pair production

    Directory of Open Access Journals (Sweden)

    Christian Kohlfürst

    2016-05-01

    Full Text Available Electron–positron pair production in space- and time-dependent electromagnetic fields is investigated. Especially, the influence of a time-dependent, inhomogeneous magnetic field on the particle momenta and the total particle yield is analyzed for the first time. The role of the Lorentz invariant E2−B2, including its sign and local values, in the pair creation process is emphasized.

  2. Latitudinal Dependence of Cosmic Rays Modulation at 1 AU and Interplanetary-Magnetic-Field Polar Correction

    CERN Document Server

    Bobik, P; Boschini, M J; Consolandi, C; Della Torre, S; Gervasi, M; Grandi, D; Kudela, K; Pensotti, S; Rancoita, P G; Rozza, D; Tacconi, M

    2012-01-01

    The cosmic rays differential intensity inside the heliosphere, for energy below 30 GeV/nuc, depends on solar activity and interplanetary magnetic field polarity. This variation, termed solar modulation, is described using a 2-D (radius and colatitude) Monte Carlo approach for solving the Parker transport equation that includes diffusion, convection, magnetic drift and adiabatic energy loss. Since the whole transport is strongly related to the interplanetary magnetic field (IMF) structure, a better understanding of his description is needed in order to reproduce the cosmic rays intensity at the Earth, as well as outside the ecliptic plane. In this work an interplanetary magnetic field model including the standard description on ecliptic region and a polar correction is presented. This treatment of the IMF, implemented in the HelMod Monte Carlo code (version 2.0), was used to determine the effects on the differential intensity of Proton at 1\\,AU and allowed one to investigate how latitudinal gradients of proton...

  3. Size-Dependent Accumulation of PEGylated Silane-Coated Magnetic Iron Oxide Nanoparticles in Murine Tumors

    DEFF Research Database (Denmark)

    Larsen, Esben Kjær Unmack; Nielsen, T.; Wittenborn, T.

    2009-01-01

    Magnetic nanoparticles (MNP) can be used as contrast-enhancing agents to visualize tumors by magnetic resonance imaging (MRI). Here we describe an easy synthesis method of magnetic nanoparticles coated with polyethylene glycol (PEG) and demonstrate size-dependent accumulation in murine tumors...... following intravenous injection. Biocompatible iron oxide MNPs coated with PEG were prepared by replacing oleic acid with a biocompatible and commercially available silane-PEG to provide an easy and effective method for chemical coating. The colloidal stable PEGylated MNPs were magnetically separated...... into two distinct size subpopulations of 20 and 40 nm mean diameters with increased phagocytic uptake observed for the 40 nm size range in vitro. MRI detection revealed greater iron accumulation in murine tumors for 40 nm nanoparticles after intravenous injection. The enhanced MRI contrast of the larger...

  4. Spin-dependent tunneling time in periodic diluted-magnetic-semiconductor/nonmagnetic-barrier superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ping-Fan; Guo, Yong, E-mail: guoy66@tsinghua.edu.cn [Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)

    2016-02-01

    We investigate the tunneling time (dwell time) in periodic diluted-magnetic-semiconductor/nonmagnetic-barrier (DMS/NB) superlattices subjected to an external magnetic field. It is found that spin-dependent resonant bands form in the spectra of dwell time, which can be effectively manipulated by not only the external magnetic field but also the geometric parameters of the system. Moreover, an intuitive semiclassical delay is defined to illustrate the behavior of the dwell time, and the former one is shown to be the result of “smoothing out” the latter one. We also find that the dwell time in diluted-magnetic-semiconductor/semiconductor superlattices behaves surprisingly different from the DMS/NB case, especially for spin-down electrons.

  5. Sublattice dependent magnetic response of dual Cr doped graphene monolayer: a full potential approach

    Science.gov (United States)

    Thakur, Jyoti; Kashyap, Manish K.; Taya, Ankur; Rani, Priti; Saini, Hardev S.

    2017-01-01

    In the present scenario, many researchers are exploring the possibility of inducing a magnetic channel in graphene by introducing various types of defects. To examine the Cr-Cr interactions in dual Cr doped graphene monolayer for magnetic response and spin polarization, the first-principles density functional theory based calculations are performed. Further, the possibility of achieving 100 % spin polarization in various possible configurations of dual Cr-doping have been explored. Dual doping of Cr atoms in graphene monolayer preferring ferromagnetic ordering, generates a spin magnetic state with a local moment of 4.00 µB. Depending upon the relative position of two Cr impurities in graphene, the ground states of doped systems are found be ferromagnetic, antiferromagnetic or paramagnetic. The origin of particular magnetic state observed in all possible dual Cr-doping configurations has been explained on the basis of RKKY indirect exchange interactions.

  6. Composition dependence of the magnetic properties of strontium hexaferrite doped with rare earth ions

    Science.gov (United States)

    Singh, Taminder; Batra, M. S.; Singh, Iqbal; Katoch, Arun

    2014-09-01

    Rare earth substituted ferrite Sr1-xRExFe12O19 (where RE = La, Gd and Dy, x = 0.0, 0.10, 0.20 and 0.30), have been prepared by employing the ceramic technique and subsequent heat treatment. The magnetic properties of the calcined samples were characterized with a Vibrating Sample Magnetometer (VSM). The samples were sintered at 1150°C for 8 hours. The samples were characterized for magnetic properties such as specific saturation magnetization MS, specific remanence magnetization Mr, and coercivity Hc as well as microstructure. It has been observed that all these parameters depend on the composition and heat treatment of the prepared samples. The coercively Hc exhibits an increase as the RE content increases in Sr1-xRExFe12O19 ferrite. With increasing RE content the MS and Mr decrease due to dissolution of RE ion into hexaferrite lattice.

  7. Magnetic field dependence of the diffusion of single dextran molecules within a hydrogel containing magnetite nanoparticles.

    Science.gov (United States)

    Al-Baradi, Ateyyah M; Mykhaylyk, Oleksandr O; Blythe, Harry J; Geoghegan, Mark

    2011-03-07

    We consider the effect of applied magnetic fields on the diffusion of single dextran molecules labeled with fluorescein isothiocyanate within a ferrogel [a composite of magnetite nanoparticles in a poly(methacrylic acid) hydrogel] using fluorescence correlation spectroscopy. We show that the mesh size of the ferrogel is controlled by the applied magnetic field, B, and scales as exp(-(4)√ξ(3)B(2)/2μ(0)k(B)T), where ξ is a correlation length, μ(0) the magnetic constant, k(B) the Boltzmann constant, and T is the absolute temperature. The diffusion coefficient of the dextran can be modeled with a simple Stokes-Einstein law, containing the same scaling behavior with magnetic field as the swelling of the hydrogel. Furthermore, the magnetic field-dependent release of dextran from the hydrogel is also controlled by the same relationship. The samples were characterized by small angle x-ray scattering (SAXS) and magnetometry experiments. Magnetic hysteresis loops from these ferrogels and zero field cooled∕field cooled measurements reveal single domain ferromagnetic behavior at room temperature with a similar coercivity for both as-prepared and fully swollen ferrogels, and for increasing magnetic nanoparticle concentration. SAXS experiments, such as the hysteresis loops, show that magnetite does not aggregate in these gels.

  8. Temperature-dependent magnetostriction as the key factor for martensite reorientation in magnetic field

    Science.gov (United States)

    L'vov, Victor A.; Kosogor, Anna

    2016-09-01

    The magnetic field application leads to spatially inhomogeneous magnetostriction of twinned ferromagnetic martensite. When the increasing field and magnetostrictive strain reach certain threshold values, the motion of twin boundaries and magnetically induced reorientation (MIR) of twinned martensite start. The MIR leads to giant magnetically induced deformation of twinned martensite. In the present article, the threshold field (TF) and temperature range of observability of MIR were calculated for the Ni-Mn-Ga martensite assuming that the threshold strain (TS) is temperature-independent. The calculations show that if the TS is of the order of 10-4, the TF strongly depends on temperature and MIR can be observed only above the limiting temperature (~220 K). If the TS is of the order of 10-6, the TF weakly depends on temperature and MIR can be observed at extremely low temperatures. The obtained theoretical results are in agreement with available experimental data.

  9. Extended gyrokinetic field theory for time-dependent magnetic confinement fields

    Energy Technology Data Exchange (ETDEWEB)

    Sugama, H.; Watanabe, T.-H.; Nunami, M. [National Institute for Fusion Science, Toki 509-5292 (Japan)

    2014-01-15

    A gyrokinetic system of equations for turbulent toroidal plasmas in time-dependent axisymmetric background magnetic fields is derived from the variational principle. Besides governing equations for gyrocenter distribution functions and turbulent electromagnetic fields, the conditions which self-consistently determine the background magnetic fields varying on a transport time scale are obtained by using the Lagrangian, which includes the constraint on the background fields. Conservation laws for energy and toroidal angular momentum of the whole system in the time-dependent background magnetic fields are naturally derived by applying Noether's theorem. It is shown that the ensemble-averaged transport equations of particles, energy, and toroidal momentum given in the present work agree with the results from the conventional recursive formulation with the WKB representation except that collisional effects are disregarded here.

  10. Size and voltage dependence of effective anisotropy in sub-100-nm perpendicular magnetic tunnel junctions

    Science.gov (United States)

    Piotrowski, Stephan K.; Bapna, Mukund; Oberdick, Samuel D.; Majetich, Sara A.; Li, Mingen; Chien, C. L.; Ahmed, Rizvi; Victora, R. H.

    2016-07-01

    Magnetic tunnel junctions with perpendicular magnetic anisotropy are investigated using a conductive atomic force microscope. The 1.23 -nm Co40Fe40B20 recording layer coercivity exhibits a size dependence which suggests single-domain behavior for diameters ≤100 nm. Focusing on devices with diameters smaller than 100 nm, we determine the effect of voltage and size on the effective device anisotropy Keff using two different techniques. Keff is extracted both from distributions of the switching fields of the recording and reference layers and from measurement of thermal fluctuations of the recording layer magnetization when a field close to the switching field is applied. The results from both sets of measurements reveal that Keff increases monotonically with decreasing junction diameter, consistent with the size dependence of the demagnetization energy density. We demonstrate that Keff can be controlled with a voltage down to the smallest size measured, 64 nm.

  11. The magnetic field dependence of cross-effect dynamic nuclear polarization under magic angle spinning

    Energy Technology Data Exchange (ETDEWEB)

    Mance, Deni; Baldus, Marc, E-mail: m.baldus@uu.nl [NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, 3584 CH Utrecht (Netherlands); Gast, Peter; Huber, Martina [Department of Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, PO Box 9504, 2300 RA Leiden (Netherlands); Ivanov, Konstantin L., E-mail: ivanov@tomo.nsc.ru [International Tomography Center, Siberian Branch of the Russian Academy of Science, Institutskaya 3a, Novosibirsk 630090, Russia and Novosibirsk State University, Pirogova 2, Novosibirsk 63009 (Russian Federation)

    2015-06-21

    We develop a theoretical description of Dynamic Nuclear Polarization (DNP) in solids under Magic Angle Spinning (MAS) to describe the magnetic field dependence of the DNP effect. The treatment is based on an efficient scheme for numerical solution of the Liouville-von Neumann equation, which explicitly takes into account the variation of magnetic interactions during the sample spinning. The dependence of the cross-effect MAS-DNP on various parameters, such as the hyperfine interaction, electron-electron dipolar interaction, microwave field strength, and electron spin relaxation rates, is analyzed. Electron spin relaxation rates are determined by electron paramagnetic resonance measurements, and calculations are compared to experimental data. Our results suggest that the observed nuclear magnetic resonance signal enhancements provided by MAS-DNP can be explained by discriminating between “bulk” and “core” nuclei and by taking into account the slow DNP build-up rate for the bulk nuclei.

  12. Co thickness dependence of structural and magnetic properties in spin quantum cross devices utilizing stray magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Kaiju, H., E-mail: kaiju@es.hokudai.ac.jp; Kasa, H.; Mori, S.; Misawa, T.; Abe, T.; Nishii, J. [Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 001-0020 (Japan); Komine, T. [Faculty of Engineering, Ibaraki University, Hitachi, Ibaraki 316-8511 (Japan)

    2015-05-07

    We investigate the Co thickness dependence of the structural and magnetic properties of Co thin-film electrodes sandwiched between borate glasses in spin quantum cross (SQC) devices that utilize stray magnetic fields. We also calculate the Co thickness dependence of the stray field between the two edges of Co thin-film electrodes in SQC devices using micromagnetic simulation. The surface roughness of Co thin films with a thickness of less than 20 nm on borate glasses is shown to be as small as 0.18 nm, at the same scanning scale as the Co film thickness, and the squareness of the hysteresis loop is shown to be as large as 0.96–1.0. As a result of the establishment of polishing techniques for Co thin-film electrodes sandwiched between borate glasses, we successfully demonstrate the formation of smooth Co edges and the generation of stray magnetic fields from Co edges. Theoretical calculation reveals that a strong stray field beyond 6 kOe is generated when the Co thickness is greater than 10 nm at a junction gap distance of 5 nm. From these experimental and calculation results, it can be concluded that SQC devices with a Co thickness of 10–20 nm can be expected to function as spin-filter devices.

  13. Zebra finches have a light-dependent magnetic compass similar to migratory birds.

    Science.gov (United States)

    Pinzon-Rodriguez, Atticus; Muheim, Rachel

    2017-04-01

    Birds have a light-dependent magnetic compass that provides information about the spatial alignment of the geomagnetic field. It is proposed to be located in the avian retina and mediated by a light-induced, radical-pair mechanism involving cryptochromes as sensory receptor molecules. To investigate how the behavioural responses of birds under different light spectra match with cryptochromes as the primary magnetoreceptor, we examined the spectral properties of the magnetic compass in zebra finches. We trained birds to relocate a food reward in a spatial orientation task using magnetic compass cues. The birds were well oriented along the trained magnetic compass axis when trained and tested under low-irradiance 521 nm green light. In the presence of a 1.4 MHz radio-frequency electromagnetic (RF)-field, the birds were disoriented, which supports the involvement of radical-pair reactions in the primary magnetoreception process. Birds trained and tested under 638 nm red light showed a weak tendency to orient ∼45 deg clockwise of the trained magnetic direction. Under low-irradiance 460 nm blue light, they tended to orient along the trained magnetic compass axis, but were disoriented under higher irradiance light. Zebra finches trained and tested under high-irradiance 430 nm indigo light were well oriented along the trained magnetic compass axis, but disoriented in the presence of a RF-field. We conclude that magnetic compass responses of zebra finches are similar to those observed in nocturnally migrating birds and agree with cryptochromes as the primary magnetoreceptor, suggesting that light-dependent, radical-pair-mediated magnetoreception is a common property for all birds, including non-migratory species. © 2017. Published by The Company of Biologists Ltd.

  14. Analysis of the static magnetic field-dependent optical transmission of Ni nanorod colloidal suspensions

    Science.gov (United States)

    Krämer, Florian; Gratz, Micha; Tschöpe, Andreas

    2016-07-01

    The magnetic field-dependent optical transmission of dilute Ni nanorod aqueous suspensions was investigated. A series of four samples of nanorods were synthesized using the AAO template method and processed to stable colloids. The distributions of their length and diameter were characterized by analysis of TEM images and revealed average diameters of ˜25 nm and different lengths in the range of 60 nm-1100 nm. The collinear magnetic and optical anisotropy was studied by static field-dependent transmission measurements of linearly polarized light parallel and perpendicular to the magnetic field direction. The experimental results were modelled assuming the field-dependent orientation distribution function of a superparamagnetic ensemble for the uniaxial ferromagnetic nanorods in liquid dispersion and extinction cross sections for longitudinal and transversal optical polarization derived from different approaches, including the electrostatic approximation and the separation of variables method, both applied to spheroidal particles, as well as finite element method simulations of spheroids and capped cylindrical particles. The extinction cross sections were compared to reveal the differences associated with the approximations of homogeneous polarization and/or particle shape. The consequences of these approximations for the quantitative analysis of magnetic field-dependent optical transmission measurements were investigated and a reliable protocol derived. Furthermore, the changes in optical cross sections induced by electromagnetic interaction between two nanorods in parallel end-to-end and side-by-side configuration as a function of their separation were studied.

  15. Mixing of photons with light pseudoscalars in time-dependent magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Arias, Paola; Arza, Ariel; Gamboa, Jorge [Universidad de Santiago de Chile, Departmento de Fisica, Santiago (Chile)

    2016-11-15

    The effects of an external time-dependent magnetic field in the conversion probability of photon- to axion-like particles are studied. Our findings show that for a certain time regime, the amplitude of the produced axion-like field can be enlarged with respect to the static case, thus enhancing the probability of conversion. (orig.)

  16. Mixing of photons with light pseudoscalars in time-dependent magnetic fields

    Science.gov (United States)

    Arias, Paola; Arza, Ariel; Gamboa, Jorge

    2016-11-01

    The effects of an external time-dependent magnetic field in the conversion probability of photon- to axion-like particles are studied. Our findings show that for a certain time regime, the amplitude of the produced axion-like field can be enlarged with respect to the static case, thus enhancing the probability of conversion.

  17. Mixing of photons with light pseudoscalars in time-dependent magnetic fields

    CERN Document Server

    Arias, Paola; Gamboa, Jorge

    2016-01-01

    The effects of an external time-dependent magnetic field in the conversion probability of photon-to-axion-like particles are studied. Our findings show that for a certain time regime, the amplitude of the produced axion-like field can be enlarged with respect to the static case, thus, enhancing the probability of conversion.

  18. Gauge Invariance of a Time-Dependent Harmonic Oscillator in Magnetic Dipole Approximation

    Institute of Scientific and Technical Information of China (English)

    WANG Fei; QIAN Shang-Wu; FU Li-Ping; WANG Jing-Shan; GUO Ke-Tao

    2008-01-01

    A manifestly gauge-invariant formulation of non-relativistic quantum mechanics is applied to the case of time-dependent harmonic oscillator in the magnetic dipole approximation. A genera/ equation for obtaining gauge-invariant transition probability amplitudes is derived.

  19. Maxwell equation violation by density dependent magnetic fields in neutron stars

    CERN Document Server

    Menezes, Débora P

    2016-01-01

    We show that the widely used density dependent magnetic field prescriptions, necessary to account for the variation of the field intensity from the crust to the core of neutron stars violate one of the Maxwell equations. We estimate how strong the violation is when different equations of state are used and check for which cases the pathological problem can be cured.

  20. A new differential equations-based model for nonlinear history-dependent magnetic behaviour

    CERN Document Server

    Aktaa, J

    2000-01-01

    The paper presents a new kind of numerical model describing nonlinear magnetic behaviour. The model is formulated as a set of differential equations taking into account history dependence phenomena like the magnetisation hysteresis as well as saturation effects. The capability of the model is demonstrated carrying out comparisons between measurements and calculations.

  1. Common and Low Frequency Variants in MERTK Are Independently Associated with Multiple Sclerosis Susceptibility with Discordant Association Dependent upon HLA-DRB1*15:01 Status.

    Directory of Open Access Journals (Sweden)

    Michele D Binder

    2016-03-01

    Full Text Available Multiple Sclerosis (MS is a chronic inflammatory demyelinating disease of the central nervous system. The risk of developing MS is strongly influenced by genetic predisposition, and over 100 loci have been established as associated with susceptibility. However, the biologically relevant variants underlying disease risk have not been defined for the vast majority of these loci, limiting the power of these genetic studies to define new avenues of research for the development of MS therapeutics. It is therefore crucial that candidate MS susceptibility loci are carefully investigated to identify the biological mechanism linking genetic polymorphism at a given gene to the increased chance of developing MS. MERTK has been established as an MS susceptibility gene and is part of a family of receptor tyrosine kinases known to be involved in the pathogenesis of demyelinating disease. In this study we have refined the association of MERTK with MS risk to independent signals from both common and low frequency variants. One of the associated variants was also found to be linked with increased expression of MERTK in monocytes and higher expression of MERTK was associated with either increased or decreased risk of developing MS, dependent upon HLA-DRB1*15:01 status. This discordant association potentially extended beyond MS susceptibility to alterations in disease course in established MS. This study provides clear evidence that distinct polymorphisms within MERTK are associated with MS susceptibility, one of which has the potential to alter MERTK transcription, which in turn can alter both susceptibility and disease course in MS patients.

  2. Quantitative Susceptibility Mapping-Based Microscopy of Magnetic Resonance Venography (QSM-mMRV for In Vivo Morphologically and Functionally Assessing Cerebromicrovasculature in Rat Stroke Model.

    Directory of Open Access Journals (Sweden)

    Meng-Chi Hsieh

    Full Text Available Abnormal cerebral oxygenation and vessel structure is a crucial feature of stroke. An imaging method with structural and functional information is necessary for diagnosis of stroke. This study applies QSM-mMRV (quantitative susceptibility mapping-based microscopic magnetic resonance venography for noninvasively detecting small cerebral venous vessels in rat stroke model. First, susceptibility mapping is optimized and calculated from magnetic resonance (MR phase images of a rat brain. Subsequently, QSM-mMRV is used to simultaneously provide information on microvascular architecture and venous oxygen saturation (SvO2, both of which can be used to evaluate the physiological and functional characteristics of microvascular changes for longitudinally monitoring and therapeutically evaluating a disease model. Morphologically, the quantification of vessel sizes using QSM-mMRV was 30% smaller than that of susceptibility-weighted imaging (SWI, which eliminated the overestimation of conventional SWI. Functionally, QSM-mMRV estimated an average SvO2 ranging from 73% to 85% for healthy rats. Finally, we also applied QSM to monitor the revascularization of post-stroke vessels from 3 to 10 days after reperfusion. QSM estimations of SvO2 were comparable to those calculated using the pulse oximeter standard metric. We conclude that QSM-mMRV is useful for longitudinally monitoring blood oxygen and might become clinically useful for assessing cerebrovascular diseases.

  3. Quantitative Susceptibility Mapping-Based Microscopy of Magnetic Resonance Venography (QSM-mMRV) for In Vivo Morphologically and Functionally Assessing Cerebromicrovasculature in Rat Stroke Model.

    Science.gov (United States)

    Hsieh, Meng-Chi; Tsai, Ching-Yi; Liao, Min-Chiao; Yang, Jenq-Lin; Su, Chia-Hao; Chen, Jyh-Horng

    2016-01-01

    Abnormal cerebral oxygenation and vessel structure is a crucial feature of stroke. An imaging method with structural and functional information is necessary for diagnosis of stroke. This study applies QSM-mMRV (quantitative susceptibility mapping-based microscopic magnetic resonance venography) for noninvasively detecting small cerebral venous vessels in rat stroke model. First, susceptibility mapping is optimized and calculated from magnetic resonance (MR) phase images of a rat brain. Subsequently, QSM-mMRV is used to simultaneously provide information on microvascular architecture and venous oxygen saturation (SvO2), both of which can be used to evaluate the physiological and functional characteristics of microvascular changes for longitudinally monitoring and therapeutically evaluating a disease model. Morphologically, the quantification of vessel sizes using QSM-mMRV was 30% smaller than that of susceptibility-weighted imaging (SWI), which eliminated the overestimation of conventional SWI. Functionally, QSM-mMRV estimated an average SvO2 ranging from 73% to 85% for healthy rats. Finally, we also applied QSM to monitor the revascularization of post-stroke vessels from 3 to 10 days after reperfusion. QSM estimations of SvO2 were comparable to those calculated using the pulse oximeter standard metric. We conclude that QSM-mMRV is useful for longitudinally monitoring blood oxygen and might become clinically useful for assessing cerebrovascular diseases.

  4. Anisotropy of magnetic susceptibility (AMS) studies of Campanian–Maastrichtian sediments of Ariyalur Group, Cauvery Basin, Tamil Nadu, India: An appraisal to Paleocurrent directions

    Indian Academy of Sciences (India)

    G Papanna; M Venkateshwarlu; V Periasamy; R Nagendra

    2014-03-01

    Oriented samples of sediments from Ariyalur Group, Cauvery Basin, south India, were studied for low field anisotropy of magnetic susceptibility (AMS) measurements to unravel the magnetic fabrics and paleocurrent directions. The results of AMS parameters of the sediments indicate primary depositional fabrics for Sillakkudi, Ottakovil and Kallamedu sandstone formations and secondary fabric for Kallankurichchi limestone formation. The obtained low degree of anisotropy (), oblate shape AMS ellipsoid and distribution of maximum (1) and minimum (3) susceptibility axes on equal area projection confirm the primary sedimentary fabric for Sillakkudi, Ottakovil and Kallamedu Formations. In the case of ferruginous, lower arenaceous, Gryphaea limestone and upper arenaceous limestone beds of Kallankurichchi Formation have recorded more than one fabric. The observed AMS parameters like shape factor () (prolate to oblate), value and random distribution of minimum (3) and maximum (1) susceptibility axes are supported for secondary fabrics in Kallankurichchi Formation as a result of post-depositional processes. Based on petrographic studies, it can be established that 1 AMS axis of biotite mineral could represent the flow direction. The established paleocurrent direction for Sillakkudi is NW–SE direction while Ottakovil and Kallamedu Formations recorded NE–SW direction. Overall the paleoflow directions observed for Ariyalur Group is NE–SW to NW–SE.

  5. Anisotropy of magnetic susceptibility (AMS) studies of Campanian-Maastrichtian sediments of Ariyalur Group, Cauvery Basin, Tamil Nadu, India: An appraisal to Paleocurrent directions

    Science.gov (United States)

    Papanna, G.; Venkateshwarlu, M.; Periasamy, V.; Nagendra, R.

    2014-03-01

    Oriented samples of sediments from Ariyalur Group, Cauvery Basin, south India, were studied for low field anisotropy of magnetic susceptibility (AMS) measurements to unravel the magnetic fabrics and paleocurrent directions. The results of AMS parameters of the sediments indicate primary depositional fabrics for Sillakkudi, Ottakovil and Kallamedu sandstone formations and secondary fabric for Kallankurichchi limestone formation. The obtained low degree of anisotropy ( P j ), oblate shape AMS ellipsoid and distribution of maximum ( K 1) and minimum ( K 3) susceptibility axes on equal area projection confirm the primary sedimentary fabric for Sillakkudi, Ottakovil and Kallamedu Formations. In the case of ferruginous, lower arenaceous, Gryphaea limestone and upper arenaceous limestone beds of Kallankurichchi Formation have recorded more than one fabric. The observed AMS parameters like shape factor ( T) (prolate to oblate), q value and random distribution of minimum ( K 3) and maximum ( K 1) susceptibility axes are supported for secondary fabrics in Kallankurichchi Formation as a result of post-depositional processes. Based on petrographic studies, it can be established that K 1 AMS axis of biotite mineral could represent the flow direction. The established paleocurrent direction for Sillakkudi is NW-SE direction while Ottakovil and Kallamedu Formations recorded NE-SW direction. Overall the paleoflow directions observed for Ariyalur Group is NE-SW to NW-SE.

  6. High Magnetic Susceptibility in a Highly Saline Sulfate-Rich Aquifer Undergoing Biodegradation of Hydrocarbon Results from Sulfate Reduction.

    Science.gov (United States)

    Atekwana, E. A.; Enright, A.; Ntarlagiannis, D.; Slater, L. D.; Bernier, R.; Beaver, C. L.; Rossbach, S.

    2016-12-01

    We investigated the chemical and stable carbon isotope composition of groundwater in a highly saline aquifer contaminated with hydrocarbon. Our aim to evaluate hydrocarbon degradation and to constrain the geochemical conditions that generated high anomalous magnetic susceptibility (MS) signatures observed at the water table interface. The occurrence of high MS in the water table fluctuating zone has been attributed to microbial iron reduction, suggesting the use of MS as a proxy for iron cycling. The highly saline aquifer had total dissolved solids concentrations of 3.7 to 29.3 g/L and sulfate concentrations of 787 to 37,100 mg/L. We compared our results for groundwater locations with high hydrocarbon contamination (total petroleum hydrocarbon (TPH) >10 mg/L), at lightly contaminated (TPH contaminations. Our results for the terminal electron acceptors (TEAs) dissolved oxygen (DO), nitrate (NO3-), dissolved iron (Fe2+) , dissolved manganese (Mn2+), sulfate (SO42-) and methane (CH4) suggest a chemically heterogeneous aquifer, probably controlled by heterogeneous distribution of TEAs and contamination (type of hydrocarbon, phase and age of contamination). The concentrations of dissolved inorganic carbon (DIC) ranged from 67 to 648 mg C/L and the stable carbon isotope (δ13CDIC) ranged from -30.0‰ to 1.0 ‰ and DIC-δ13CDIC modeling indicates that the carbon in the DIC is derived primarily from hydrocarbon degradation. The concentrations of Fe2+ in the aquifer ranged from 0.1 to 55.8 mg/L, but was mostly low, averaging 2.7+10.9 mg/L. Given the low Fe2+ [AE1] in the aqueous phase and the high MS at contaminated locations, we suggest that the high MS observed does not arise from iron reduction but rather from sulfate reduction. Sulfate reduction produces H2S which reacts with Fe2+ to produce ferrous sulfide (Fe2+S) or the mixed valence greigite (Fe2+Fe3+2S4). We conclude that in highly saline aquifers with high concentrations of sulfate and contaminated with

  7. Translation of Pur-α is targeted by cellular miRNAs to modulate the differentiation-dependent susceptibility of monocytes to HIV-1 infection.

    Science.gov (United States)

    Shen, Chan-Juan; Jia, Yan-Hui; Tian, Ren-Rong; Ding, Ming; Zhang, Chiyu; Wang, Jian-Hua

    2012-11-01

    The postentry restriction of HIV-1 replication in monocytes can be relieved when they differentiate to dendritic cells (DCs) or macrophages. Multiple mechanisms have been proposed to interpret the differentiation-dependent susceptibility of monocytes to HIV-1 infection, and the absence of host-cell-encoded essential factors for HIV-1 completing the life cycle may provide an explanation. We have analyzed the gene expression profile in monocytes by mRNA microarray and compared it with that of differentiated DCs. We demonstrated that purine-rich element binding protein α (Pur-α), a host-cell-encoded ubiquitous, sequence-specific DNA- and RNA-binding protein, showed inadequate expression in monocytes, and the translation of Pur-α mRNA was repressed by cell-expressed microRNA (miRNA). These Pur-α-targeted miRNAs modulated the differentiation-dependent susceptibility of monocytes/DCs to HIV-1 infection, because rescue of Pur-α expression by transfection of miRNA inhibitors relieved the restriction of HIV-1 infection in monocytes, and ectopic input of miRNA mimics significantly reduced HIV-1 infection of monocyte-derived DCs (MDDCs). Collectively, our data emphasized that inadequate host factors contribute to HIV-1 restriction in monocytes, and cellular miRNAs modulate differentiation-dependent susceptibility of host cells to HIV-1 infection. Elaboration of HIV-1 restriction in host cells facilitates our understanding of viral pathogenesis and the search for a new antiviral strategy.

  8. Imaging technique for magnetic susceptibility and resistivity by electromagnetic tomography. 1. Numerical experiments; EM tomography ni yoru taijiritsu to hiteiko no imaging gijutsu. 1. Suchi jikken ni yoru kisoteki kento

    Energy Technology Data Exchange (ETDEWEB)

    Sakashita, S.; Fukuoka, K. [OYO Corp., Tokyo (Japan)

    1998-10-01

    This paper proposes imaging techniques which utilize electromagnetic waves in a wide frequency band for magnetic susceptibility and resistivity, and describes the basic investigation results by numerical experiments. The electromagnetic tomography generates electromagnetic waves by passing current through a receiving coil, to measure their magnetic components by an induction coil. The magnetic field generated by the electromagnetic waves can be handled as a pseudo-static one, when the current is passed at a sufficiently low frequency, and the field response measured by an induction coil contains information mainly regarding magnetic susceptibility. The field generates induction as transmitting frequency is increased, and the measured magnetic response contains mainly regarding resistivity. They can be measured for imaging susceptibility, when distance between the holes is 50 to 100m or less and transmitting frequency is 100 to 10Hz or less. The use of the expanded Born approximation allows to establish a high-speed model for imaging resistivity. 23 refs., 13 figs.

  9. Temperature dependent spin and orbital magnetization in TbCo{sub 2}: Magnetic Compton scattering and first-principles investigations

    Energy Technology Data Exchange (ETDEWEB)

    Ahuja, B.L., E-mail: blahuja@yahoo.com [Department of Physics, M.L. Sukhadia University, Udaipur 313001 (India); Mund, H.S. [Department of Physics, M.L. Sukhadia University, Udaipur 313001 (India); Sahariya, Jagrati [Department of Physics, Manipal University Jaipur, Jaipur 303007 (India); Dashora, Alpa [Department of Physics, University of Mumbai, Vidyanagri, Santacruz (E), Mumbai 400098 (India); Halder, Madhumita; Yusuf, S.M. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Itou, M.; Sakurai, Y. [Japan Synchrotron Radiation Research Institute, SPring8, 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan)

    2015-06-05

    Highlights: • Presented temperature dependent spin momentum densities in TbCo{sub 2}. • Explored spin and orbital magnetic moments at different sites. • Contribution of local and itinerant moments in TbCo{sub 2} is explained. • First-principles calculations are performed to supplement the experiment. - Abstract: Spin-polarized Compton profiles of TbCo{sub 2} have been measured to elucidate the interesting behavior of spin and orbital moments at different temperatures. The magnetic Compton profiles (MCPs) have been analyzed in terms of site specific spin moments due to Tb-4f electrons, Co and itinerant electrons. The temperature dependence of the orbital moment has been deduced using Compton and magnetometry data ranging between 6 and 300 K. The present data exhibit a decrease in the ratio of orbital to spin moments from 43.9% to 35.0% (while going from 6 to 300 K). First-principles calculations within DFT + U scheme have also been performed to confirm the spin-, orbital- and site specific-magnetic moments in TbCo{sub 2}. An antiparallel exchange coupling between the Tb-4f and Co spin moments is found. The orbital moment is found to have a parallel coupling with the Tb spin moment, as evident from the experimental MCPs. From first-principles data it is seen that the orbital moments of Tb and Co sites are antiparallel to each other, as in the case of their spin magnetic moments. The present experimental study also shows an existence of an itinerant moment which is coupled ferromagnetically with the Tb-4f spin moment.

  10. Concentration dependence of the wings of a dipole-broadened magnetic resonance line in magnetically diluted lattices

    Energy Technology Data Exchange (ETDEWEB)

    Zobov, V. E., E-mail: rsa@iph.krasn.ru [Russian Academy of Sciences, Kirenskii Institute of Physics, Siberian Branch (Russian Federation); Kucherov, M. M. [Siberian Federal University, Institute of Space and Information Technologies (Russian Federation)

    2017-01-15

    The singularities of the time autocorrelation functions (ACFs) of magnetically diluted spin systems with dipole–dipole interaction (DDI), which determine the high-frequency asymptotics of autocorrelation functions and the wings of a magnetic resonance line, are studied. Using the self-consistent fluctuating local field approximation, nonlinear equations are derived for autocorrelation functions averaged over the independent random arrangement of spins (magnetic atoms) in a diamagnetic lattice with different spin concentrations. The equations take into account the specificity of the dipole–dipole interaction. First, due to its axial symmetry in a strong static magnetic field, the autocorrelation functions of longitudinal and transverse spin components are described by different equations. Second, the long-range type of the dipole–dipole interaction is taken into account by separating contributions into the local field from distant and near spins. The recurrent equations are obtained for the expansion coefficients of autocorrelation functions in power series in time. From them, the numerical value of the coordinate of the nearest singularity of the autocorrelation function is found on the imaginary time axis, which is equal to the radius of convergence of these expansions. It is shown that in the strong dilution case, the logarithmic concentration dependence of the coordinate of the singularity is observed, which is caused by the presence of a cluster of near spins whose fraction is small but contribution to the modulation frequency is large. As an example a silicon crystal with different {sup 29}Si concentrations in magnetic fields directed along three crystallographic axes is considered.

  11. Modeling Spin Fluctuations and Magnetic Excitations from Time-Dependent Density Functional Theory

    Science.gov (United States)

    Gorni, Tommaso; Timrov, Iurii; Dal Corso, Andrea; Baroni, Stefano

    Harnessing spin fluctuations and magnetic excitations in materials is key in many fields of technology, spanning from memory devices to information transfer and processing, to name but a few. A proper understanding of the interplay between collective and single-particle spin excitations is still lacking, and it is expected that first-principle simulations based on TDDFT may shed light on this interplay, as well as on the role of important effects such as relativistic ones and related magnetic anisotropies. All the numerical approaches proposed so far to tackle this problem are based on the computationally demanding solution of the Sternheimer equations for the response orbitals or the even more demanding solution of coupled Dyson equations for the spin and charge susceptibilities. The Liouville-Lanczos approach to TDDFT has already proven to be a valuable alternative, the most striking of its features being the avoidance of sums over unoccupied single-particle states and the frequency-independence of the main numerical bottleneck. In this work we present an extension of this methodology to magnetic systems and its implementation in the Quantum ESPRESSO distribution, together with a few preliminary results on the magnon dispersions in bulk Fe.

  12. Susceptibility of pancreatic beta cells to fatty a