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Sample records for magnetic susceptibility study

  1. Magnetic susceptibility and magnetization studies of some commercial austenitic stainless steels

    International Nuclear Information System (INIS)

    Collings, E.W.

    1979-01-01

    Results of magnetic susceptibility measurements using the Curie magnetic force technique are reported for six AISI 300-series alloys 310S, 304, 304L, 304N, 316, 316L as well as AWS 330 weld metal and Inconel 625. The temperature ranged from 5 to 416 0 K. Magnetization measurements over the temperature range 3 to 297 0 K, performed using a vibrating-sample magnetometer, are also reported. Alloy compositions and sample preparation procedures are discussed and numerical results of the study are presented. Magnetic characteristics of the four principal types of austenitic stainless steels studied are summarized

  2. Study of the magnetic susceptibilities of some plutonium derivatives

    International Nuclear Information System (INIS)

    Raphael, G.

    1969-06-01

    We present a detailed description of an automatic recording apparatus for magnetic susceptibility measurement of radioactive samples in the temperature range 4 K - 1200 K. We have measured the magnetic susceptibility of various plutonium compounds: - PuO 2 , Pu 2 O 3 , PuO 2-x , - PuS, Pu 2 S 3 , Pu 3 S 4 , (U x Pu 1-x )S - PuN - PuC 1-x (N,O,H,vacancy), Pu 2 C 3 , (U 0.85 Pu 0.15 )C. The curves of susceptibilities versus temperature show many magnetic transitions. The interpretation of these results shows the existence of magnetic moments carried by the 5 f electrons and localized on the metallic sites as well as the great influence of the 'crystal field' in all these compounds. (author) [fr

  3. Magnetic susceptibility characterisation of superparamagnetic microspheres

    Science.gov (United States)

    Grob, David Tim; Wise, Naomi; Oduwole, Olayinka; Sheard, Steve

    2018-04-01

    The separation of magnetic materials in microsystems using magnetophoresis has increased in popularity. The wide variety and availability of magnetic beads has fuelled this drive. It is important to know the magnetic characteristics of the microspheres in order to accurately use them in separation processes integrated on a lab-on-a-chip device. To investigate the magnetic susceptibility of magnetic microspheres, the magnetic responsiveness of three types of Dynabeads microspheres were tested using two different approaches. The magnetophoretic mobility of individual microspheres is studied using a particle tracking system and the magnetization of each type of Dynabeads microsphere is measured using SQUID relaxometry. The magnetic beads' susceptibility is obtained at four different applied magnetic fields in the range of 38-70 mT for both the mobility and SQUID measurements. The susceptibility values in both approaches show a consistent magnetic field dependence.

  4. Finite perturbation studies of magnetic susceptibility and shielding with GIAO

    International Nuclear Information System (INIS)

    Zaucer, M.; Pumpernik, D.; Hladnik, M.; Azman, A.

    1977-01-01

    The magnetic susceptibility tensor and proton and fluorine magnetic shielding tensors are calculated for F 2 and (FHF) - using an ab initio finite perturbation method with gauge-invariant atomic orbitals (GIAO). The discussion of the basis set deficiency shows that the calculated values for the susceptibilities are reliable. Simple additivity (Pascal rule) for the susceptibility is confirmed. (orig.) [de

  5. Magnetic susceptibility measurements of boring cores obtained from regional hydrological study project

    International Nuclear Information System (INIS)

    Hasegawa, Ken

    2010-02-01

    We measured the magnetic susceptibility of boring cores obtained from the Regional Hydrological Study Project to interpret the aeromagnetic survey data which was carried out in Tono area with about 40km square surrounding Tono Geoscience Center. The result of measurements indicates that the magnetic susceptibility of the Toki Granite is not distributed uniformly and the maximum value becomes two orders in magnitude larger than its minimum value. (author)

  6. Acoustic investigation of magnetic susceptibility of liquid metals

    International Nuclear Information System (INIS)

    Tekuchev, V.V.; Barashkov, B.I.; Ivanova, I.V.; Rygalov, L.N.

    2008-01-01

    An acoustic method is proposed for studying the specific magnetic susceptibility of metal melts. For the first time, magnetic susceptibilities of francium, beryllium, scandium, yttrium, vanadium, niobium, rhenium, palladium, and platinum in the liquid phase at their melting points, as well as temperature dependences of magnetic susceptibilities of cesium, yttrium, and vanadium over the temperature range from melting points to boiling points have been estimated [ru

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

    International Nuclear Information System (INIS)

    Khatiwada, R; Kendrick, R; Khosravi, M; Peters, M; Smith, E; Snow, W M; Dennis, L

    2016-01-01

    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 experimental error. These results verify the well-known Wiedemann additivity law for the magnetic susceptibility of inert mixtures of materials and thereby realize the ability to produce materials with small but tunable magnetic susceptibility. For our particular scientific application, we are also looking for materials with the largest possible number of neutrons and protons per unit volume. The gallium–indium alloys fabricated and measured in this work possess to our knowledge the smallest ratio of volume magnetic susceptibility to nucleon number density per unit volume for a room temperature liquid, and the tungsten-bismuth pressed powder mixtures possess to our knowledge the smallest ratio of volume magnetic susceptibility to nucleon number density per unit volume for a room temperature solid. This ratio is a figure of merit for a certain class of precision experiments that search for possible exotic spin-dependent forces of Nature. (paper)

  8. High-frequency, transient magnetic susceptibility of ferroelectrics

    Science.gov (United States)

    Grimes, Craig A.

    1996-10-01

    A significant high-frequency magnetic susceptibility was measured both in weakly polarized and nonpolarized samples of barium titanate, lead zirconate titanate, and carnauba wax. Magnetic susceptibility measurements were made from 10 to 500 MHz using a thin film permeameter at room temperature; initial susceptibilities ranged from 0.1 to 2.5. These values are larger than expected for paramagnets and smaller than expected for ferromagnets. It was found that the magnetic susceptibility decreases rapidly with exposure to the exciting field. The origin of the magnetic susceptibility is thought to originate with the applied time varying electric field associated with the susceptibility measurements. An electric field acts to rotate an electric dipole, creating a magnetic quadrupole if the two moments are balanced, and a net magnetic dipole moment if imbalanced. It is thought that local electrostatic fields created at ferroelectric domain discontinuities associated with grain boundaries create an imbalance in the anion rotation that results in a net, measurable, magnetic moment. The origin of the magnetic aftereffect may be due to the local heating of the material through the moving charges associated with the magnetic moment.

  9. Magnetic irreversibility in granular superconductors: ac susceptibility study

    International Nuclear Information System (INIS)

    Perez, F.; Obradors, X.; Fontcuberta, J.; Vallet, M.; Gonzalez-Calbet, J.

    1991-01-01

    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.)

  10. Magnetic susceptibility, nanorheology, and magnetoviscosity of magnetic nanoparticles in viscoelastic environments

    Science.gov (United States)

    Ilg, Patrick; Evangelopoulos, Apostolos E. A. S.

    2018-03-01

    While magnetic nanoparticles suspended in Newtonian solvents (ferrofluids) have been intensively studied in recent years, the effects of viscoelasticity of the surrounding medium on the nanoparticle dynamics are much less understood. Here we investigate a mesoscopic model for the orientational dynamics of isolated magnetic nanoparticles subject to external fields, viscous and viscoelastic friction, as well as the corresponding random torques. We solve the model analytically in the overdamped limit for weak viscoelasticity. By comparison to Brownian dynamics simulations we establish the limits of validity of the analytical solution. We find that viscoelasticity not only slows down the magnetization relaxation, shifts the peak of the imaginary magnetic susceptibility χ″ to lower frequencies, and increases the magnetoviscosity but also leads to nonexponential relaxation and a broadening of χ″. The model we study also allows us to test a recent proposal for using magnetic susceptibility measurements as a nanorheological tool using a variant of the Germant-DiMarzio-Bishop relation. We find for the present model and certain parameter ranges that the relation of the magnetic susceptibility to the shear modulus is satisfied to a good approximation.

  11. The magnetic susceptibility of soils in Krakow, southern Poland

    Science.gov (United States)

    Wojas, Anna

    2017-06-01

    Studies into the magnetic susceptibility have been used to assess the soils contamination in the Krakow area. The results of topsoil (over a 2 × 2 km grid), subsoil (37 shallow holes) and soil samples (112) measurements were presented as maps of soil magnetic susceptibility (both volume and mass) illustrating the distribution of parameters in topsoil horizon (0-10 cm) and differential magnetic susceptibility maps between topsoil horizon and subsoil (40-60 cm). All evidence leads to the finding that the highest values of magnetic susceptibility of soil are found exclusively in industrial areas. Taking into consideration the type of land use, the high median value (89.8 × 10-8 m3kg-1) was obtained for samples of cultivated soils and is likely to be connected with occurrence of fertile soil (chernozem). Moreover, enrichment of soils with Pb and Zn accompanies magnetic susceptibility anomalies in the vicinity of the high roads and in the steelworks area, respectively.

  12. 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.

  13. Magnetic susceptibilities of integrable quantum ladders

    International Nuclear Information System (INIS)

    Park, Soo A; Lee, K.

    2001-01-01

    As an extension of previous studies, we consider the magnetic susceptibilities of a coupled spin chain model at low temperature and of a more realistic model at low temperature and of a more realistic model having a t-J ladder structure at zero temperature. The magnetic susceptibilities for both models are obtained numerically when the coupling constant is greater than its critical value. In this region, the ladders behave as a single chain for H c and as two independent chains for H>H c , showing a divergence at H c . This divergence is expected to smear out at a finite temperature

  14. Structural properties and magnetic susceptibility of iron-intercalated titanium ditelluride

    International Nuclear Information System (INIS)

    Pleshchev, V.G.; Titov, A.N.; Titova, S.G.; Kuranov, A.V.

    1997-01-01

    Structural peculiarities and magnetic susceptibility of titanium ditelluride, intercalated by iron, are studied. It is established that the basic motive of crystal structure by intercalation is preserved and the iron atoms are locates in the van der Waals gaps in positions with octahedral coordination. It is shown that the magnetic susceptibility of the Fe 0.25 TiT 2 sample increases approximately by 20 times. The magnetic susceptibility for the Fe 0.33 TiTe 2 samples becomes even much higher

  15. Features of magnetic susceptibility and inhomogeneous magnetic state in La-Sr manganites

    International Nuclear Information System (INIS)

    Dovgij, V.T.; Linnik, A.I.; Kamenev, V.I.; Prokopenko, V.K.; Mikhajlov, V.I.; Khokhlov, V.A.; Kadontseva, A.M.; Linnik, T.A.; Davydejko, N.V.; Turchenko, V.A.

    2007-01-01

    Anomalous magnetic susceptibility has been observed in mono- and polycrystalline (ceramic) samples of La-Sr manganites. The oscillations of the magnetic susceptibility observed for monocrystal samples in the vicinity of the Curie temperature (and in the paramagnetic region) are explained by the existence of magnetic clusters. The appearance of susceptibility oscillations in ceramic samples is attributed to the formation of magnetic clusters, which may occur both in grains (at the interface between ferro- and antiferromagnetic phases) and at the grain boundaries [ru

  16. Low-temperature susceptibility of concentrated magnetic fluids

    Science.gov (United States)

    Pshenichnikov, Alexander F.; Lebedev, Alexander V.

    2004-09-01

    The initial susceptibility of concentrated magnetic fluids (ferrocolloids) has been experimentally investigated at low temperatures. The results obtained indicate that the interparticle dipole-dipole interactions can increase the susceptibility by several times as compared to the Langevin value. It is shown that good agreement between recent theoretical models and experimental observations can be achieved by introducing a correction for coefficients in the series expansion of susceptibility in powers of density and aggregation parameter. A modified equation for equilibrium susceptibility is offered to sum over corrections made by Kalikmanov (Statistical Physics of Fluids, Springer-Verlag, Berlin, 2001) and by B. Huke and M. Lücke (Phys. Rev. E 67, 051403, 2003). The equation gives good quantitative agreement with the experimental data in the wide range of temperature and magnetic particles concentration. It has been found that in some cases the magnetic fluid solidification occurs at temperature several tens of kelvins higher than the crystallization temperature of the carrier liquid. The solidification temperature of magnetic fluids is independent of particle concentration (i.e., magneto-dipole interparticle interactions) and dependent on the surfactant type and carrier liquid. This finding allows us to suggest that molecular interactions and generation of some large-scale structure from colloidal particles in magnetic fluids are responsible for magnetic fluid solidification. If the magnetic fluid contains the particles with the Brownian relaxation mechanism of the magnetic moment, the solidification manifests itself as the peak on the "susceptibility-temperature" curve. This fact proves the dynamic nature of the observed peak: it arises from blocking the Brownian mechanism of the magnetization relaxation.

  17. 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.

  18. Definition of a magnetic susceptibility of conglomerates with magnetite particles. Particularities of defining single particle susceptibility

    Science.gov (United States)

    Sandulyak, A. A.; Sandulyak, A. V.; Ershova, V.; Pamme, N.; Ngmasom, B.; Iles, A.

    2017-11-01

    Data of a magnetic susceptibility of ferro-and the ferrimagnetic particles of many technogenic, natural, special media are especially demanded for the solution of various tasks connected with purposeful magnetic impact on these particles. One of productive approaches to definition of a magnetic susceptibility χ of these particles consists in receiving experimental data of a susceptibility of disperse samples 〈 χ 〉 with a disperse phase of these particles. The paper expounds and analyses the results of experiments on defining (by Faraday method in a magnetic field with intensity H = 90-730 kA/m) the magnetic susceptibility 〈 χ 〉 of disperse samples (conglomerates) with a given volume ratio γ of magnetite particles (γ = 0.0065-0.25). The corresponding families of concentration and field dependences are provided alongside with discussing the applicability of linear and exponential functions to describe these dependences. We consider the possibility of defining single particles susceptibility χ (with simultaneous obtaining field dependence of this susceptibility) by the commonly used relation χ = 〈 χ 〉 /γ both at relatively small (preferable for accuracy reasons) values γ - to γ = 0.02…0.025, as well as at increased values γ - up to γ = 0.25. The data χ are provided depending on H and correlating with known data at H matter magnetic susceptibility χm (for the case when the particles are traditionally likened to balls with the characteristic for them demagnetising factor equalling 1/3) complies with the anticipated inverse function χm ∼ 1/H in the studied area H (where magnetization M expressed as M = χH reaches saturation M = Const).

  19. Out-of-phase magnetic susceptibility and environmental magnetism

    Czech Academy of Sciences Publication Activity Database

    Hrouda, F.; Chadima, Martin; Ježek, J.

    2016-01-01

    Roč. 18 (2016), EGU2016-6808 ISSN 1607-7962. [European Geosciences Union General Assembly 2016. 17.04.2016-22.04.2016, Vienna] Institutional support: RVO:67985831 Keywords : paleomagnetism * magnetic susceptibility * environmental magnetism Subject RIV: DE - Earth Magnetism, Geodesy, Geography http://meetingorganizer.copernicus.org/EGU2016/EGU2016-6808.pdf

  20. Absolute method of measuring magnetic susceptibility

    Science.gov (United States)

    Thorpe, A.; Senftle, F.E.

    1959-01-01

    An absolute method of standardization and measurement of the magnetic susceptibility of small samples is presented which can be applied to most techniques based on the Faraday method. The fact that the susceptibility is a function of the area under the curve of sample displacement versus distance of the magnet from the sample, offers a simple method of measuring the susceptibility without recourse to a standard sample. Typical results on a few substances are compared with reported values, and an error of less than 2% can be achieved. ?? 1959 The American Institute of Physics.

  1. Initial magnetic susceptibility of the diluted magnetopolymer elastic composites

    International Nuclear Information System (INIS)

    Borin, D.Yu.; Odenbach, S.

    2017-01-01

    In this work diluted magnetopolymer elastic composites based on magnetic microparticles are experimentally studied. Considered samples have varied concentration of the magnetic powder and different structural anisotropy. Experimental data on magnetic properties are accomplished by microstructural observations performed using X-Ray tomography. Influence of the particles amount and structuring effects on the initial magnetic susceptibility of the composites as well as the applicability of the Maxwell-Garnett approximation, which is widely used in considerations of magnetopolymer elastic composites, are evaluated. It is demonstrated that the approximation works well for diluted samples containing randomly distributed magnetic particles and for the diluted samples with chain-like structures oriented perpendicular to an externally applied field, while it fails to predict the susceptibility of the samples with structures oriented parallel to the field. Moreover, it is shown, that variation of the chains morphology does not significantly change the composite initial magnetic susceptibility. - Highlights: • The Maxwell-Garnet prediction works well for the diluted isotropic composites. • The Maxwell-Garnet prediction can be used for composites with structures oriented perpendicular to an applied field. • Chains oriented parallel to an applied field significantly increase the composite initial magnetic susceptibility. • The number and thickness of chains is not of the highest importance for the diluted composites. • The crucial reason of the observed effect is expected to be the demagnetisation factor of the chains.

  2. Real-time and quantitative isotropic spatial resolution susceptibility imaging for magnetic nanoparticles

    Science.gov (United States)

    Pi, Shiqiang; Liu, Wenzhong; Jiang, Tao

    2018-03-01

    The magnetic transparency of biological tissue allows the magnetic nanoparticle (MNP) to be a promising functional sensor and contrast agent. The complex susceptibility of MNPs, strongly influenced by particle concentration, excitation magnetic field and their surrounding microenvironment, provides significant implications for biomedical applications. Therefore, magnetic susceptibility imaging of high spatial resolution will give more detailed information during the process of MNP-aided diagnosis and therapy. In this study, we present a novel spatial magnetic susceptibility extraction method for MNPs under a gradient magnetic field, a low-frequency drive magnetic field, and a weak strength high-frequency magnetic field. Based on this novel method, a magnetic particle susceptibility imaging (MPSI) of millimeter-level spatial resolution (<3 mm) was achieved using our homemade imaging system. Corroborated by the experimental results, the MPSI shows real-time (1 s per frame acquisition) and quantitative abilities, and isotropic high resolution.

  3. Magnetic susceptibility in the edged topological disordered nanoscopic cylinder

    International Nuclear Information System (INIS)

    Faizabadi, Edris; Omidi, Mahboubeh

    2011-01-01

    The effects of edged topological disorder on magnetic susceptibility are investigated in a nanoscopic cylinder threaded by a magnetic flux. Persistent current versus even or odd number of electrons shows different signs in ordered and disordered cylinders and also in short or long ones. In addition, temperature-averaged susceptibility has only diamagnetic signs in strong regimes and it is associated with paramagnetic signs in ordered and weak disordered ones. Besides, in an edged topological disordered cylinder, the temperature-averaged susceptibility decreases by raising the temperature somewhat and then increasing initiates and finally at high temperature tends to zero as the ordered one. - Research highlights: → Magnetic susceptibility in one-dimensional topological disordered quantum ring. → Edged topological disorder effect on magnetic susceptibility in nanoscopic cylinder. → Edged topological disorder effect on temperature-averaged susceptibility in cylinder.

  4. Effect of centrifugation on dynamic susceptibility of magnetic fluids

    International Nuclear Information System (INIS)

    Pshenichnikov, Alexander; Lebedev, Alexander; Lakhtina, Ekaterina; Kuznetsov, Andrey

    2017-01-01

    Highlights: • Six samples of magnetic fluid were obtained by centrifuging two base ferrocolloids. • Aggregates in magnetic fluids are main reason of dynamic susceptibility dispersion. • Centrifugation is an effective way of changing the dynamic susceptibility. - Abstract: The dispersive composition, dynamic susceptibility and spectrum of times of magnetization relaxation for six samples of magnetic fluid obtained by centrifuging two base colloidal solutions of the magnetite in kerosene was investigated experimentally. The base solutions differed by the concentration of the magnetic phase and the width of the particle size distribution. The procedure of cluster analysis allowing one to estimate the characteristic sizes of aggregates with uncompensated magnetic moments was described. The results of the magnetogranulometric and cluster analyses were discussed. It was shown that centrifugation has a strong effect on the physical properties of the separated fractions, which is related to the spatial redistribution of particles and multi-particle aggregates. The presence of aggregates in magnetic fluids is interpreted as the main reason of low-frequency (0.1–10 kHz) dispersion of the dynamic susceptibility. The obtained results count in favor of using centrifugation as an effective means of changing the dynamic susceptibility over wide limits and obtaining fluids with the specified type of susceptibility dispersion.

  5. Effect of centrifugation on dynamic susceptibility of magnetic fluids

    Energy Technology Data Exchange (ETDEWEB)

    Pshenichnikov, Alexander, E-mail: pshenichnikov@icmm.ru; Lebedev, Alexander; Lakhtina, Ekaterina; Kuznetsov, Andrey

    2017-06-15

    Highlights: • Six samples of magnetic fluid were obtained by centrifuging two base ferrocolloids. • Aggregates in magnetic fluids are main reason of dynamic susceptibility dispersion. • Centrifugation is an effective way of changing the dynamic susceptibility. - Abstract: The dispersive composition, dynamic susceptibility and spectrum of times of magnetization relaxation for six samples of magnetic fluid obtained by centrifuging two base colloidal solutions of the magnetite in kerosene was investigated experimentally. The base solutions differed by the concentration of the magnetic phase and the width of the particle size distribution. The procedure of cluster analysis allowing one to estimate the characteristic sizes of aggregates with uncompensated magnetic moments was described. The results of the magnetogranulometric and cluster analyses were discussed. It was shown that centrifugation has a strong effect on the physical properties of the separated fractions, which is related to the spatial redistribution of particles and multi-particle aggregates. The presence of aggregates in magnetic fluids is interpreted as the main reason of low-frequency (0.1–10 kHz) dispersion of the dynamic susceptibility. The obtained results count in favor of using centrifugation as an effective means of changing the dynamic susceptibility over wide limits and obtaining fluids with the specified type of susceptibility dispersion.

  6. Magnetism of a sigma-phase Fe{sub 60}V{sub 40} alloy: Magnetic susceptibilities and magnetocaloric effect studies

    Energy Technology Data Exchange (ETDEWEB)

    Bałanda, Maria [Institute of Nuclear Physics, Polish Academy of Science, PL-31-342 Kraków (Poland); Dubiel, Stanisław M., E-mail: Stanislaw.Dubiel@fis.agh.edu.pl [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, PL-30-059 Kraków (Poland); Pełka, Robert [Institute of Nuclear Physics, Polish Academy of Science, PL-31-342 Kraków (Poland)

    2017-06-15

    Highlights: • Sigma-phase Fe{sub 60}V{sub 40} alloy was studied by means of AC and DC magnetic susceptibilities. • Re-entrant character of the magnetism has been evidenced. • Curie temperature was found as ∼169 K and the spin-freezing temperature as ∼164 K. • Critical exponents β = 0.6, γ = 1.0 and Δ = 1.6 were determined. • Magnetocaloric effect was investigated. - Abstract: Magnetic properties of a sigma-phase Fe{sub 60}V{sub 40} intermetallic compound were studied by means of ac and dc magnetic susceptibility and magnetocaloric effect measurements. The compound is a soft magnet yet it was found to behave like a re-entrant spin-glass system. The magnetic ordering temperature was found to be T{sub C} ≈ 170 K, while the spin-freezing temperature was ∼164 K. Its relative shift per decade of ac frequency was 0.002, a value smaller than that typical of canonical spin-glasses. Magnetic entropy change, ΔS, in the vicinity of T{sub C} was determined for magnetic field, H, ranging between 5 and 50 kOe. Analysis of ΔS in terms of the power law yielded the critical exponent, n, vs. temperature with the minimum value of 0.75 at T{sub C}, while from the analysis of a relative shift of the maximum value of ΔS with the field a critical exponent Δ = 1.7 was obtained. Based on scaling laws relationships values of other two exponents viz. β = 0.6 and γ = 1 were determined.

  7. Inflationary susceptibilities, duality and large-scale magnetic fields generation

    CERN Document Server

    Giovannini, Massimo

    2013-01-01

    We investigate what can be said about the interaction of scalar fields with Abelian gauge fields during a quasi-de Sitter phase of expansion and under the assumption that the electric and the magnetic susceptibilities do not coincide. The duality symmetry, transforming the magnetic susceptibility into the inverse of the electric susceptibility, exchanges the magnetic and electric power spectra. The mismatch between the two susceptibilities determines an effective refractive index affecting the evolution of the canonical fields. The constraints imposed by the duration of the inflationary phase and by the magnetogenesis requirements pin down the rate of variation of the susceptibilities that is consistent with the observations of the magnetic field strength over astrophysical and cosmological scales but avoids back-reaction problems. The parameter space of this magnetogenesis scenario is wider than in the case when the susceptibilities are equal, as it happens when the inflaton or some other spectator field is ...

  8. Magnetic relaxation phenomena in the chiral magnet Fe1 -xCoxSi : An ac susceptibility study

    Science.gov (United States)

    Bannenberg, L. J.; Lefering, A. J. E.; Kakurai, K.; Onose, Y.; Endoh, Y.; Tokura, Y.; Pappas, C.

    2016-10-01

    We present a systematic study of the ac susceptibility of the chiral magnet Fe1 -xCoxSi with x =0.30 covering four orders of magnitude in frequencies from 0.1 Hz to 1 kHz, with particular emphasis to the pronounced history dependence. Characteristic relaxation times ranging from a few milliseconds to tens of seconds are observed around the skyrmion lattice A phase, the helical-to-conical transition and in a region above TC. The distribution of relaxation frequencies around the A phase is broad, asymmetric, and originates from multiple coexisting relaxation processes. The pronounced dependence of the magnetic phase diagram on the magnetic history and cooling rates as well as the asymmetric frequency dependence and slow dynamics suggest more complicated physical phenomena in Fe0.7Co0.3Si than in other chiral magnets.

  9. Crystal structure and magnetic susceptibility of UOSe single crystals

    International Nuclear Information System (INIS)

    Kaczorowski, D.; Muenster Univ.; Poettgen, R.; Jeitschko, W.; Gajek, Z.; Zygmunt, A.

    1993-01-01

    The crystal structure and magnetic susceptibility behaviour of UOSe single crystals have been studied. UOSe crystalizes in the tetragonal PbFC1-type structure (space group P4/nmm) with the lattice parameters: a = 390.38(5) pm and c = 698.05(9) pm. It orders antiferromagnetically at T N =100±2 K and exhibits a very strong anisotropy in the susceptibility vs temperature variation. The magnetic and thermodynamic properties of UOSe are successfully interpreted in the framework of a perturbative ab initio crystal field approach. (Author)

  10. Crystal structure and magnetic susceptibility of UOSe single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kaczorowski, D. (Polish Academy of Sciences, Wroclaw (Poland). Inst. for Low Temperature and Structure Research Muenster Univ. (Germany). Anorganisch-Chemisches Inst.); Poettgen, R.; Jeitschko, W. (Muenster Univ. (Germany). Anorganisch-Chemisches Inst.); Gajek, Z.; Zygmunt, A. (Polish Academy of Sciences, Wroclaw (Poland). Inst. for Low Temperature and Structure Research)

    1993-01-01

    The crystal structure and magnetic susceptibility behaviour of UOSe single crystals have been studied. UOSe crystalizes in the tetragonal PbFC1-type structure (space group P4/nmm) with the lattice parameters: a = 390.38(5) pm and c = 698.05(9) pm. It orders antiferromagnetically at T[sub N]=100[+-]2 K and exhibits a very strong anisotropy in the susceptibility vs temperature variation. The magnetic and thermodynamic properties of UOSe are successfully interpreted in the framework of a perturbative ab initio crystal field approach. (Author).

  11. Effects of phase constitution of Zr-Nb alloys on their magnetic susceptibilities

    International Nuclear Information System (INIS)

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

    2009-01-01

    The magnetic susceptibilities and microstructures of Zr-Nb binary alloys were investigated to develop a new metallic biomaterial with a low magnetic susceptibility for magnetic resonance imaging (MRI). The magnetic susceptibility was measured with a magnetic susceptibility balance, and the microstructure was evaluated with an X-ray diffractometer (XRD), an optical microscope (OM), and a transmission electron microscope (TEM). Zr-Nb alloys as-cast showed a minimum value of magnetic susceptibility between 3 and 9 mass% Nb, and the value abruptly increased up to 20 mass% Nb, followed by a gradual increase with the increase of the Nb content. XRD, OM, and TEM revealed that the minimum value of the susceptibility was closely related to the appearance of the athermal ω phase in the β phase. Since the magnetic susceptibility of Zr-3Nb alloy consisting of an α' phase was as low as that of Zr-9Nb alloy consisting of the β and ω phases, that of the ω phase was lower than that of the α' and β phases. When Zr-16Nb alloy was heat-treated, the isothermal ω phase appeared, and, simultaneously, the magnetic susceptibility decreased. Therefore, the ω phase contributes to the decrease of the magnetic susceptibility, independently of the formation process of the ω phase. The magnetic susceptibility of the Zr-3Nb alloy as-cast was almost one-third that of Ti-6Al-4V alloy, which is commonly used for medical implant devices. Zr-Nb alloys are useful for medical devices used under MRI. (author)

  12. Magnetic susceptibility of curium pnictides

    International Nuclear Information System (INIS)

    Nave, S.E.; Huray, P.G.; Peterson, J.R.; Damien, D.A.; Haire, R.G.

    1981-09-01

    The magnetic susceptibility of microgram quantities of 248 CmP and 248 CmSb has been determined with the use of a SQUID micromagnetic susceptometer over the temperature range 4.2 to 340 K and in the applied magnetic field range of 0.45 to 1600 G. The fcc (NaCl-type) samples yield magnetic transitions at 73K and 162 K for the phosphide and antimonide, respectively. Together with published magnetic data for CmN and CmAs, these results indicate spatially extended exchange interactions between the relatively localized 5f electrons of the metallic actinide atoms

  13. Effect of centrifugation on dynamic susceptibility of magnetic fluids

    Science.gov (United States)

    Pshenichnikov, Alexander; Lebedev, Alexander; Lakhtina, Ekaterina; Kuznetsov, Andrey

    2017-06-01

    The dispersive composition, dynamic susceptibility and spectrum of times of magnetization relaxation for six samples of magnetic fluid obtained by centrifuging two base colloidal solutions of the magnetite in kerosene was investigated experimentally. The base solutions differed by the concentration of the magnetic phase and the width of the particle size distribution. The procedure of cluster analysis allowing one to estimate the characteristic sizes of aggregates with uncompensated magnetic moments was described. The results of the magnetogranulometric and cluster analyses were discussed. It was shown that centrifugation has a strong effect on the physical properties of the separated fractions, which is related to the spatial redistribution of particles and multi-particle aggregates. The presence of aggregates in magnetic fluids is interpreted as the main reason of low-frequency (0.1-10 kHz) dispersion of the dynamic susceptibility. The obtained results count in favor of using centrifugation as an effective means of changing the dynamic susceptibility over wide limits and obtaining fluids with the specified type of susceptibility dispersion.

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

    International Nuclear Information System (INIS)

    Ficko, Bradley W.; Nadar, Priyanka M.; Diamond, Solomon G.

    2015-01-01

    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 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 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 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

  15. Nature of the magnetic susceptibility of dysprosium. Paramagnetic susceptibility of dysprosium - yttrium alloys

    International Nuclear Information System (INIS)

    Demidov, V.G.; Levitin, R.Z.; Chistyakov, O.D.

    1976-01-01

    The paramagnetic susceptibility of single crystals of dysprosium-yttirum alloys is measured in the basal plane and along the hexagonal axis. It is shown that the susceptibility of the alloys obeys the Curie-Weiss law, the effective magnetic moments allong the different directions being the same and the paramagnetic Curie temperatures being different. The difference between the paramagnetic Curie temperatures in the basal plane and along the hexagonal axis is independent of the dysprosium concentration in the alloy. As a comparison with the theoretical models of magnetic anisotropy shows, this is an indication that the magnetic anisotropy of dysprosium - yttrium alloys is of a single-ion nature

  16. Quantitative susceptibility mapping (QSM): Decoding MRI data for a tissue magnetic biomarker

    Science.gov (United States)

    Wang, Yi; Liu, Tian

    2015-01-01

    In MRI, the main magnetic field polarizes the electron cloud of a molecule, generating a chemical shift for observer protons within the molecule and a magnetic susceptibility inhomogeneity field for observer protons outside the molecule. The number of water protons surrounding a molecule for detecting its magnetic susceptibility is vastly greater than the number of protons within the molecule for detecting its chemical shift. However, the study of tissue magnetic susceptibility has been hindered by poor molecular specificities of hitherto used methods based on MRI signal phase and T2* contrast, which depend convolutedly on surrounding susceptibility sources. Deconvolution of the MRI signal phase can determine tissue susceptibility but is challenged by the lack of MRI signal in the background and by the zeroes in the dipole kernel. Recently, physically meaningful regularizations, including the Bayesian approach, have been developed to enable accurate quantitative susceptibility mapping (QSM) for studying iron distribution, metabolic oxygen consumption, blood degradation, calcification, demyelination, and other pathophysiological susceptibility changes, as well as contrast agent biodistribution in MRI. This paper attempts to summarize the basic physical concepts and essential algorithmic steps in QSM, to describe clinical and technical issues under active development, and to provide references, codes, and testing data for readers interested in QSM. Magn Reson Med 73:82–101, 2015. © 2014 The Authors. Magnetic Resonance in Medicine Published by Wiley Periodicals, Inc. on behalf of International Society of Medicine in Resonance. This is an open access article under the terms of the Creative commons Attribution License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited. PMID:25044035

  17. Magnetic susceptibility measurement using 2D magnetic resonance imaging

    Czech Academy of Sciences Publication Activity Database

    Marcon, P.; Bartušek, Karel; Burdkova, M.; Dokoupil, Zdeněk

    2011-01-01

    Roč. 22, č. 10 (2011), 105702:1-8 ISSN 0957-0233 R&D Projects: GA ČR GAP102/11/0318; GA MŠk ED0017/01/01 Institutional research plan: CEZ:AV0Z20650511 Keywords : magnetic flux density * magnetic susceptibility * MRI * MR signal * reaction field Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.494, year: 2011

  18. Soil magnetic susceptibility as indicator of radioactive contamination

    International Nuclear Information System (INIS)

    Curda, S.

    2006-01-01

    Measurement of magnetic susceptibility is a method, which is used in many areas of research. The locality Ak-Tjuz is typical example of old ecological load. One of the negative effects represents radioactive contamination. This situation is caused by environmental disaster in 1964. For useful reparation it is really necessary to determinate the surface range of contamination. And measurement of the magnetic susceptibility could be the suitable method for that kind of monitoring. (author)

  19. Magnetic susceptibility: a proxy method of estimating increased pollution

    International Nuclear Information System (INIS)

    Kluciarova, D.; Gregorova, D.; Tunyi, I.

    2004-01-01

    A need for rapid and inexpensive (proxy) methods of outlining areas exposed to increased pollution by atmospheric particulates of industrial origin caused scientists in various fields to use and validate different non-traditional (or non-chemical) techniques. Among them, soil magnetometry seems to be a suitable tool. This method is based on the knowledge that ferrimagnetic particles, namely magnetite, are produced from pyrite during combustion of fossil fuel. Besides the combustion processes, magnetic particles can also originate from road traffic, for example, or can be included in various waste-water outlets. In our study we examine the magnetic susceptibility as a convenient measure of determining the concentration of (ferri) magnetic minerals by rapid and non-destructive means. We used for measure KLY-2 Kappabridge. Concentration of ferrimagnetic minerals in different soils is linked to pollution sources. Higher χ values were observed in soils on the territory in Istebne (47383x10 -6 SI ). The susceptibility anomaly may be caused by particular geological circumstances and can be related to high content of ferromagnetic minerals in the host rocks. Positive correlation of magnetic susceptibility are conditioned by industrial contamination mainly by metal working factories and by traffic. The proposed method can be successfully applied in determining heavy metal pollution of soils on the city territories. (authors)

  20. Spatial distribution of topsoil magnetic susceptibility in Sawahlunto City, West Sumatera

    Science.gov (United States)

    Afdal; Wahyuni, E. S.

    2018-03-01

    A research to determine the spatial distribution of top soil magnetic suceptibility at Sawahlunto City, West Sumatra has been conducted. The top soil samples were taken at four locations ie the downtown area, the steam power plant area, the agricultural area, and coal mine area. At each location, the soil samples were taken at 10 points at a depth of 20 cm. Magnetic susceptibility were measured using Bartington MS2B Magnetic Susceptibility Meter. The topsoil samples from Sawahlunto city have relatively low average value of the magnetic susceptibility that is 67.0×10-8 m3/kg. The magnetic susceptibility of topsoil samples from downtown area have the average and the highest value of magnetic susceptibility (100.6×10-8 and 259.9×10-8 m3/kg), and followed by sample from the steam power plant area (98.4×10-8 and 258.0×10-8 m3/kg), the agricultural area (56.2×10-8 and 83.7×10-8 m3/kg), and coal mine area (12.9×10-8 and 26.8×10-8 m3/kg). Soil samples from the steam power plant area have the widest range of magnetic susceptibility value range from 0.3 × 10-8 to 258.0 × 10-8 m3/kg.

  1. Soil and water pollution studies from a waste site deposit in Bantama, Kumasi, Ghana using magnetic susceptibility measurements

    International Nuclear Information System (INIS)

    Hadi, M.; Preko, K.; Ashia, T.

    2012-01-01

    The magnetic susceptibility of soil and water samples from around the Uadara barracks waste site deposit in Bantama, a suburb of Kumasi was measured with the aim of investigating the potential threat of pollution to the soil, streams, fish ponds and other water sources at the site around Armed Forces Senior High School campus which shares the same premises with the barracks. The studied soil samples were picked from the near surface (∼10 cm depth) along profiles taken from the waste site towards the stream and the ponds. Again, water samples were picked along the stream and from ten (10) ponds aligned along the stream. Laboratory measurements of the magnetic susceptibility were done using the Bartington MS2 metre and the MS2B dual frequency sensor for the soil samples, and the MS2G sensor for the water samples. The soil samples from the site registered an average magnetic susceptibility of 180. 04 x 10 -5 SI whereas the water samples recorded an average of -2.3 x 10 -6 SI showing a significant increment in comparison with the standard water magnetic susceptibility of -9.04 x 10 -6 SI. Thus, not withstand the lithology of the area studied, the presence of heavy metals and other chemical waste materials form the Uadara barracks garbage deposit site were found to greatly pollute the soil and particularly the water bodies around the Armed Forces Senior High School. (au)

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

    International Nuclear Information System (INIS)

    Van den Bosch, A.

    2008-01-01

    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?

  4. Effect of structural transition on magnetic susceptibility of tantalum carbide

    International Nuclear Information System (INIS)

    Lipatnikov, V.N.; Gusev, A.I.; Rempel', A.A.; Shvejkin, G.P.

    1987-01-01

    Ordering of carbon atoms and vacancies in nonmetal sublattice of TaC y is investigated for the first time by methods of magnetic susceptibility and structural neutron diffraction analysis. Measurements of magnetic susceptibility were conducted on high-sensitive magnetic scales in temperature interval of 300 - 1300 K with holding at each temperature up to the establishment of constant, nonchanging in the course of time value of susceptibility x. When investigating x-hardened tantalum carbide within the interval of TaC 0.82 - TaC 0.85 compositions under the conditions of slow heating, it was observed nonrecorded earlier irreversible decrease of susceptibility at temperature of 960 - 1000 K. With further temperature increase T>T tr it was observed at first even and than uneven increase of x value at a temperature of T tr equal to 1090, 1130 and 1150 K for TaC 0.82 , TaC 0.83 and TaC 0.85 respectively. The measuring of magnetic susceptibility of the same samples at temperature decrease reveals the presence of susceptibility temperature hysteresis in the interval of 1070 - 1090, 1100 - 1130 and 1120 - 1150 for TaC 0.82 , TaC 0.83 and TaC 0.85 . Reversible susceptibility jump corresponding to the temperature hysteresis range at dependences of x(T), is connected with equilibrium structural phase transition of order-disorder

  5. Ising model on tangled chain - 2: Magnetization and susceptibility

    International Nuclear Information System (INIS)

    Mejdani, R.

    1993-05-01

    In the preceding paper we have considered an Ising model defined on tangled chain to study the behaviour of the free energy and entropy, particularly in the zero-field and zero-temperature limit. In this paper, following the main line and basing on some results of the previous work, we shall study in the ''language'' of state configurations the behaviour of the magnetization and the susceptibility for different conditions of the model, to understand better the competition between the ferromagnetic bonds along the chain and the antiferromagnetic additional bonds across the chain. Particularly interesting is the behaviour of the susceptibility in the zero-field and zero-temperature limit. Exact solutions for the magnetization and susceptibility, generated by analytical calculations and iterative algorithms, are described. The additional bonds, introduced as a form of perfectly disorder, indicate a particular effect on the spin correlation. We found that the condition J=-J' between the ferromagnetic interaction J along the chain and the antiferromagnetic interaction J' across the chain is somewhat as a ''transition-region'' condition for this behaviour. (author). 16 refs, 14 figs

  6. Mean magnetic susceptibility regularized susceptibility tensor imaging (MMSR-STI) for estimating orientations of white matter fibers in human brain.

    Science.gov (United States)

    Li, Xu; van Zijl, Peter C M

    2014-09-01

    An increasing number of studies show that magnetic susceptibility in white matter fibers is anisotropic and may be described by a tensor. However, the limited head rotation possible for in vivo human studies leads to an ill-conditioned inverse problem in susceptibility tensor imaging (STI). Here we suggest the combined use of limiting the susceptibility anisotropy to white matter and imposing morphology constraints on the mean magnetic susceptibility (MMS) for regularizing the STI inverse problem. The proposed MMS regularized STI (MMSR-STI) method was tested using computer simulations and in vivo human data collected at 3T. The fiber orientation estimated from both the STI and MMSR-STI methods was compared to that from diffusion tensor imaging (DTI). Computer simulations show that the MMSR-STI method provides a more accurate estimation of the susceptibility tensor than the conventional STI approach. Similarly, in vivo data show that use of the MMSR-STI method leads to a smaller difference between the fiber orientation estimated from STI and DTI for most selected white matter fibers. The proposed regularization strategy for STI can improve estimation of the susceptibility tensor in white matter. © 2014 Wiley Periodicals, Inc.

  7. Magnetic susceptibility measuring probe utilizing a compensation coil

    International Nuclear Information System (INIS)

    Bonnet, Jean; Fournet, Julien.

    1978-01-01

    This invention concerns a magnetic susceptibility measuring probe. It is used, inter alia, in logging, to wit continuous logging of the magnetic susceptibility of the ground throughout the length of a bore hole. The purpose of this invention is to increase the sensitivity of this type of probe by creating a side focusing effect . To this end, it provides for the use of a compensation winding, coaxial with the measurement winding and arranged symmetrically to the latter with respect to the centre of the induction windings [fr

  8. Magnetic susceptibility of molecular carbon: nanotubes and fullerite

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, A P; Haddon, R C; Zhou, O; Fleming, R M; Zhang, J; McClure, S M; Smalley, R E [AT T Bell Laboratories, Murray Hill, NJ (United States)

    1994-07-01

    Elemental carbon can be synthesized in a variety of geometrical forms, from three-dimensional extended structures (diamond) to finite molecules (C[sub 60] fullerite). Results are presented here on the magnetic susceptibility of the least well-understood members of this family, nanotubes and C[sub 60] fullerite. (1) 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. (2) High-resolution magnetic susceptibility data on C[sub 60] 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 C[sub 60]. 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.

  9. Susceptibility effects in nuclear magnetic resonance imaging

    International Nuclear Information System (INIS)

    Ziener, Christian Herbert

    2008-01-01

    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.)

  10. Magnetic susceptibility of 244Cm metal and 249Cf metal

    International Nuclear Information System (INIS)

    Fujita, D.K.; Parsons, T.C.; Edelstein, N.; Noe, M.; Peterson, J.R.

    1975-07-01

    The first magnetic susceptibility measurements made on the expanded fcc phase of 249 Cf metal are reported. Further measurements are needed on other Cf metal phases. Another measurement of the magnetic susceptibility of 244 Cm metal in a limited temperature range has been reported. The result does not agree with previously reported values. Further work is continuing on the synthesis of 244 Cm metal and 248 Cm metal and magnetic measurements on these samples. (auth)

  11. Magnetic-susceptibility and heat-capacity measurements on PrRhSb

    International Nuclear Information System (INIS)

    Malik, S.K.; Takeya, H.; Gschneidner, K.A. Jr.

    1994-01-01

    Magnetic-susceptibility (ac and dc) and heat-capacity measurements have been carried out on the compound PrRhSb. These measurements reveal two magnetic transitions in this compound---one at about 18 K and the other around 6 K. In the dc susceptibility the 18-K transition is evident as the temperature below which a magnetic correlation sets in and the susceptibility is found to be field dependent. The lower transition manifests as a peak in the susceptibility of zero-field-cooled samples which were measured in low applied fields. The electronic-specific-heat coefficient, γ, is found to be 33 mJ/mol K 2 between 40 and 70 K after correcting for the lattice contribution taken to be the same as in its La analog. The γ value is fairly large for a Pr compound and may be indicative of moderately heavy quasiparticles. A Kondo-type interaction of the Pr 4f electrons with the conduction electrons may be responsible for high-magnetic-ordering temperatures and the moderately large γ value in this compound

  12. The use of magnetic susceptibility measurements to determine ...

    African Journals Online (AJOL)

    This research work presents a study on the application of magnetic susceptibility measurements and geochemical analysis for mapping or assessing heavy metal pollution in the agricultural soil in road proximity. The research work was also done to check any runoff of heavy metals pollution to the Owabi dam which serves ...

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    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

  14. 3D and 4D magnetic susceptibility tomography based on complex MR images

    Science.gov (United States)

    Chen, Zikuan; Calhoun, Vince D

    2014-11-11

    Magnetic susceptibility is the physical property for T2*-weighted magnetic resonance imaging (T2*MRI). The invention relates to methods for reconstructing an internal distribution (3D map) of magnetic susceptibility values, .chi. (x,y,z), of an object, from 3D T2*MRI phase images, by using Computed Inverse Magnetic Resonance Imaging (CIMRI) tomography. The CIMRI technique solves the inverse problem of the 3D convolution by executing a 3D Total Variation (TV) regularized iterative convolution scheme, using a split Bregman iteration algorithm. The reconstruction of .chi. (x,y,z) can be designed for low-pass, band-pass, and high-pass features by using a convolution kernel that is modified from the standard dipole kernel. Multiple reconstructions can be implemented in parallel, and averaging the reconstructions can suppress noise. 4D dynamic magnetic susceptibility tomography can be implemented by reconstructing a 3D susceptibility volume from a 3D phase volume by performing 3D CIMRI magnetic susceptibility tomography at each snapshot time.

  15. Neptunium tetrabromide: a Moessbauer and magnetic susceptibility study below 200K

    International Nuclear Information System (INIS)

    Stevens, J.L.; Jones, E.R. Jr.; Stone, J.A.; Karraker, D.G.

    1974-01-01

    NpBr 4 was studied by 237 Np Moessbauer resonance from 4.2 to 20 0 K and by vibrating-sample magnetometer from 2.2 to 70.5 0 K. The magnetic susceptibility exhibits typical Curie-Weiss behavior about 20 0 K and displays a sharp peak at 12.5 +- 0.5 0 K indicating an antiferromagnetic transition. The Moessbauer spectrum at 4.2 0 K agrees with previous work by Stone and Pillinger [J.A. Stone and W.L. Pillinger, Sym. Faraday Soc., 1, 77(1967)]. At approximately 13 0 K, there is a small decline in H/sub eff/ with paramagnetic relaxation effects remaining at higher temperatures. (U.S.)

  16. Magnetization, magnetic susceptibility, effective magnetic moment of Fe3+ ions in Bi25FeO39 ferrite

    International Nuclear Information System (INIS)

    Zatsiupa, A.A.; Bashkirov, L.A.; Troyanchuk, I.O.; Petrov, G.S.; Galyas, A.I.; Lobanovsky, L.S.; Truhanov, S.V.

    2014-01-01

    Magnetic susceptibility for ferrite Bi 25 FeO 39 is measured at 5–950 K in the magnetic field of 0.86 T. It is shown that Bi 25 FeO 39 is paramagnetic in the temperature range 5−950 K. The saturation magnetization is equal to 5.04μ B per formula unit at 5 K in a magnetic field of 10 T. It is found that at 5−300 K the effective magnetic moment of Fe 3+ ions in Bi 25 FeO 39 is equal to 5.82μ B . - Graphical abstract: The dependence of the magnetization (n, μ B ) on the magnetic field for one formula unit of Bi 25 FeO 39 at 5 K. - Highlights: • Magnetic susceptibility for Bi 25 FeO 39 is measured at 5–950 K in the magnetic field of 0.86 T. • It is shown that Bi 25 FeO 39 is paramagnetic in the temperature range 5−950 K. • The saturation magnetization is equal to 5.04μ B per formula unit at 5 K in a magnetic field of 10 T

  17. Detection of superparamagnetic particles in soils developed on basalts using frequency- and amplitude-dependent magnetic susceptibility

    Science.gov (United States)

    Grison, H.; Petrovsky, E.; Kapicka, A.

    2016-12-01

    In rock, soil and environmental studies dealing with magnetic methods, the frequency-dependent magnetic susceptibility (κFD%) is parameter generally accepted as a tool for identification of ultrafine superparamagnetic (SP) particles. This parameter became an indicator of pedogenic magnetic fraction (increased pedogenesis). Despite the number of studies using this parameter, knowledge about threshold values of κFD% is not clear enough and this parameter may be misinterpreted. Moreover, in strongly magnetic soils, magnetic signal of the SP (mostly pedogenic) minerals may be masked by dominant lithological signal, carried by coarse-grain mineral fraction; therefore, influence of pedogenesis is hard to detect. The aim of this contribution is to compare results in determination of ultrafine SP magnetic particles in soils determined using different instruments: (a) Bartington MS2B dual-frequency meter, and (b) more sensitive AGICO Kappameter MFK1-FA. The values of the κFD % obtained by the Bartington MS2B varied from 0.9 to 5.8% (mass-specific magnetic susceptibility from 119 to 1533 × 10-8 m3/kg) while the AGICO MFK1-FA varied from 3.7 to 8.2% (mass-specific magnetic susceptibility from 295 to 1843 × 10-8 m3/kg). Although both instruments suggest significant portion of SP magnetic particles, the results can't be interpreted using the generally accepted threshold values based on Bartington data. However, our results suggest that relation between the mass-specific magnetic susceptibility and κFD% along whole soil profile may serve as suitable tool in discriminating between lithogenic and pedogenic control of magnetic fraction in the soil profile. Moreover, we propose new concept of identification of SP particles, based on field-dependent magnetic susceptibility. Its behaviour shows distinct features with significant change at amplitudes of about 100 A/m. Below this value, susceptibility decreases with increasing amplitude, reflecting saturation of magnetization due

  18. 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.

  19. Static magnetic susceptibility of radiopaque NiTiPt and NiTiEr

    Science.gov (United States)

    Chovan, Drahomír; Gandhi, Abbasi; Butler, James; Tofail, Syed A. M.

    2018-04-01

    Magnetic properties of metallic alloys used in biomedical industry are important for the magnetic resonance imaging (MRI). If the alloys were to be used for long term implants or as guiding devices, safety of the patient as well as the medical staff has to be ensured. Strong response to the external magnetic field can cause mechanical damage to the patients body. In this paper we present magnetic susceptibility of nickel rich, ternary NiTiPt and NiTiEr to static magnetic field. We show that the magnetic susceptibility of these radiopaque alloys has values in low paramagnetic region comparable to the binary nickel-titanium. Furthermore, we studied the effect of the thermal and mechanical treatments on magnetic properties. Despite deviation from linear M (H) treated samples spanning small region around H = 0 , the linearity of the M (H) and χ =d M /d H values suggest that these ternary alloys are safe to use under MRI conditions.

  20. Quantitative interpretation of the magnetic susceptibility frequency dependence

    Science.gov (United States)

    Ustra, Andrea; Mendonça, Carlos A.; Leite, Aruã; Jovane, Luigi; Trindade, Ricardo I. F.

    2018-05-01

    Low-field mass-specific magnetic susceptibility (MS) measurements using multifrequency alternating fields are commonly used to evaluate concentration of ferrimagnetic particles in the transition of superparamagnetic (SP) to stable single domain (SSD). In classical palaeomagnetic analyses, this measurement serves as a preliminary assessment of rock samples providing rapid, non-destructive, economical and easy information of magnetic properties. The SP-SSD transition is relevant in environmental studies because it has been associated with several geological and biogeochemical processes affecting magnetic mineralogy. MS is a complex function of mineral-type and grain-size distribution, as well as measuring parameters such as external field magnitude and frequency. In this work, we propose a new technique to obtain quantitative information on grain-size variations of magnetic particles in the SP-SSD transition by inverting frequency-dependent susceptibility. We introduce a descriptive parameter named as `limiting frequency effect' that provides an accurate estimation of MS loss with frequency. Numerical simulations show the methodology capability in providing data fitting and model parameters in many practical situations. Real-data applications with magnetite nanoparticles and core samples from sediments of Poggio le Guaine section of Umbria-Marche Basin (Italy) provide additional information not clearly recognized when interpreting cruder MS data. Caution is needed when interpreting frequency dependence in terms of single relaxation processes, which are not universally applicable and depend upon the nature of magnetic mineral in the material. Nevertheless, the proposed technique is a promising tool for SP-SSD content analyses.

  1. Magnetic susceptibility of YbN

    International Nuclear Information System (INIS)

    Zhou, Y.; Bowen, S.P.; Koelling, D.D.; Monnier, R.

    1991-01-01

    Applying the Zwicknagl, Zevin, and Fulde (ZZF) approximation for the spectral densities of the occupied and empty f states resulting from a degenerate-Anderson-impurity model, which incorporates crystal fields, we compute the low-temperature magnetic susceptibility of YbN. The model, in which each crystal-field level couples to the band states with its own hybridization function, has previously been successfully applied without the ZZF approximation to explain the specific-heat structure at low temperatures. The ZZF approximation removes the spurious zero-temperature behavior of the parent noncrossing approximation for the susceptibility. Surprisingly, even at the low crystal-field degeneracy (N=2) of YbN, the Shiba relation is very nearly satisfied. The appropriate experimental impurity susceptibility for comparison is extracted from the measurement by removing an empirical exchange interaction. The resultant Kondo temperature (T 0 =8.49 K) is consistent with previous specific-heat estimates (10--11 K), and the agreement with experiment is good

  2. High temperature magnetic susceptibility of the Nb-H system

    International Nuclear Information System (INIS)

    Welter, J.-M.

    1983-01-01

    The magnetic susceptibility chi(T,x) of various NbHsub(x) specimens with 0 - 5 to 1.25 x 10 - 5 cm 3 g - 1 in this hydrogen concentration range and exhibits a marked break at x approximately 0.6. An estimate of the Pauli paramagnetic spin susceptibility chisub(P) for the two limiting concentrations allowed the evaluation of the orbital paramagnetic susceptibility chisub(O). For x = 0 and x approximately 0.8 the values of chisub(P) are 1.05 x 10 - 5 cm 3 g - 1 and 0.39 x 10 - 5 cm 3 g - 1 respectively and the values of chisub(O) are 1.73 x 10 - 5 cm 3 g - 1 and 1.08 x 10 - 5 cm 3 g - 1 respectively. The magnetic susceptibility decreases by approximately 10% on going from the concentrated solid solution to the monohydride. (Auth.)

  3. Confined Brownian motion of individual magnetic nanoparticles on a chip: Characterization of magnetic susceptibility.

    NARCIS (Netherlands)

    van Ommering, K.; Nieuwenhuis, J.H.; IJzendoorn, van L.J.; Koopmans, B.; Prins, M.W.J.

    2006-01-01

    An increasing number of biomedical applications requires detailed knowledge of the magnetic susceptibility of individual particles. With conventional techniques it is very difficult to analyze individual particles smaller than 1 µm. The authors demonstrate how the susceptibility of individual

  4. Magnetic susceptibility measurements on Bi - Sn alloys

    International Nuclear Information System (INIS)

    Mustaffa bin Haji Abdullah

    1985-01-01

    Magnetic susceptibility measurements on eight samples of tin-rich and three samples of bismuth-rich Bi-Sn alloys were made from 85K to 300K by Faraday's method. The susceptibilities of the eight tin-rich samples are positive and greater than the susceptibility of pure tin. The values are approximately constant at low temperatures but decreasing a little bit with increasing temperature. This result is interpreted as due to the predominant contribution of the Pauli spin paramagnetic susceptibility. A small decrease in susceptibility with temperature is interpreted as due to the effect of the second order term in the expression for spin paramagnetic susceptibility. The fluctuation of the susceptibility for alloys of different composition is interpreted as due to the effect of the density of states at the Fermi levels. The three samples of bismuth-rich alloys show a transition to diamagnetic property, where the diamagnetism is increased with temperature. This result is predominant and due to the diamagnetic contribution from the ions. The increase in susceptibility with temperature is interpreted as due to an increase in the effective radii of the ions due to thermal expansion. (author)

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

    International Nuclear Information System (INIS)

    Fano, Walter Gustavo; Boggi, Silvina; Razzitte, Adrian Cesar

    2011-01-01

    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.

  6. 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

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, D. Sanjeev, E-mail: sanjeevchs@gmail.com [School of Physics, University of Hyderabad, Hyderabad 500046 (India); Mukhopadhyay, Soma [Department of Physics, CMR College of Engineering and Technology, Hyderabad (India); Chatterjee, Ashok [School of Physics, University of Hyderabad, Hyderabad 500046 (India)

    2016-11-15

    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. - Highlights: • Temperature has no effect on magnetization and susceptibility in the diamagnetic regime but reduces the height of the paramagnetic peak. • Electron-electron interaction reduces magnetization and susceptibility in the diamagnetic region. • Rashba spin–orbit interaction shifts the paramagnetic peak towards higher magnetic fields. • Dresselhaus spin–orbit interaction shifts the paramagnetic peak towards lower magnetic fields. • Spin–orbit interaction has no effect on magnetization and susceptibility at larger temperatures.

  7. The use of magnetic susceptibility as a forensic search tool.

    Science.gov (United States)

    Pringle, Jamie K; Giubertoni, Matteo; Cassidy, Nigel J; Wisniewski, Kristopher D; Hansen, James D; Linford, Neil T; Daniels, Rebecca M

    2015-01-01

    There are various techniques available for forensic search teams to employ to successfully detect a buried object. Near-surface geophysical search methods have been dominated by ground penetrating radar but recently other techniques, such as electrical resistivity, have become more common. This paper discusses magnetic susceptibility as a simple surface search tool illustrated by various research studies. These suggest magnetic susceptibility to be a relatively low cost, quick and effective tool, compared to other geophysical methods, to determine disturbed ground above buried objects and burnt surface remains in a variety of soil types. Further research should collect datasets over objects of known burial ages for comparison purposes and used in forensic search cases to validate the technique. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  8. Magnetic Susceptibility and Heavy Metals in Guano from South Sulawesi Caves

    Science.gov (United States)

    Rifai, H.; Putra, R.; Fadila, M. R.; Erni, E.; Wurster, C. M.

    2018-04-01

    Measurement of some magnetic properties have been performed on vertical profile from South Sulawesi caves (Mampu and Bubau) by using low cost, rapid, sensitive and non destructive magnetic method. The aim is to attempt to use magnetic characters as a fingerprint for anthropogenic pollution in the caves. Guano samples were collected every 5 cm at a certain section of Mampu and Bubau cave, South Sulawesi, starting from surface through 300 cm in depth of mampu Cave and 30 cm of Bubau Cave. The magnetic parameters such as magnetic susceptibility and percentage frequency dependence susceptibility were measured using the Bartington MS2-MS2B instruments and supported by X-Ray Fluoroscence (XRF) to know their element composition. The results show that the samples had variations in magnetic susceptibility from 3.5 to 242.6 x 10‑8 m3/kg for Mampu Cave and from 8.6 to 106.5 x 10‑8 m3/kg for Bubau Cave and also magnetic domain. Then, the XRF results show that the caves contain several heavy metals. Magnetic and heavy metal analyses showing that the magnetic minerals in caves are lithogenic (Fe-bearing minerals) in origin and anthropogenic (Zn content) in the caves.

  9. SU-F-I-24: Feasibility of Magnetic Susceptibility to Relative Electron Density Conversion Method for Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Ito, K; Kadoya, N; Chiba, M; Matsushita, H; Jingu, K [Tohoku University Graduate School of Medicine, Sendai, Miyagi (Japan); Sato, K; Nagasaka, T; Yamanaka, K [Tohoku University Hospital, Sendai, Miyagi (Japan); Dobashi, S; Takeda, K [Tohoku University, Sendai, Miyagi (Japan)

    2016-06-15

    Purpose: The aim of this study is to develop radiation treatment planning using magnetic susceptibility obtained from quantitative susceptibility mapping (QSM) via MR imaging. This study demonstrates the feasibility of a method for generating a substitute for a CT image from an MRI. Methods: The head of a healthy volunteer was scanned using a CT scanner and a 3.0 T MRI scanner. The CT imaging was performed with a slice thickness of 2.5 mm at 80 and 120 kV (dual-energy scan). These CT images were converted to relative electron density (rED) using the CT-rED conversion table generated by a previous dual-energy CT scan. The CT-rED conversion table was generated using the conversion of the energy-subtracted CT number to rED via a single linear relationship. One T2 star-weighted 3D gradient echo-based sequence with four different echo times images was acquired using the MRI scanner. These T2 star-weighted images were used to estimate the phase data. To estimate the local field map, a Laplacian unwrapping of the phase and background field removal algorithm were implemented to process phase data. To generate a magnetic susceptibility map from the local field map, we used morphology enabled dipole inversion method. The rED map was resampled to the same resolution as magnetic susceptibility, and the magnetic susceptibility-rED conversion table was obtained via voxel-by-voxel mapping between the magnetic susceptibility and rED maps. Results: A correlation between magnetic susceptibility and rED is not observed through our method. Conclusion: Our results show that the correlation between magnetic susceptibility and rED is not observed. As the next step, we assume that the voxel of the magnetic susceptibility map comprises two materials, such as water (0 ppm) and bone (-2.2 ppm) or water and marrow (0.81ppm). The elements of each voxel were estimated from the ratio of the two materials.

  10. Magnetic susceptibility as a method of investigation of short-range order in strongly nonstoichiometric carbides

    International Nuclear Information System (INIS)

    Nazarova, S.Z.; Gusev, A.I.

    2001-01-01

    Magnetic susceptibility in disordered and ordered carbides of transition metals (M = Ti, Zr, Hf, Nb, Ta) was studied, the results are generalized. It was ascertained that the change in carbide susceptibility induced by deviation from stoichiometry stems from specific features of electronic spectra of the compounds. The use of magnetic susceptibility for determining structural disorder-order transitions is discussed. It is shown that change in the contribution made by orbital paramagnetism, resulting from short-range order formation, is the reason of decrease in susceptibility of nonstoichiometric carbides during the ordering. Experimentally obtained data on susceptibility permitted evaluating short- and far-range order parameters in NbC y , TaC y , TiC y and HfC y carbides [ru

  11. Magnetic susceptibility imaging with a nonionic contrast agent

    International Nuclear Information System (INIS)

    Cacheris, W.; Rocklage, S.M.; Quay, S.; Dow, W.; Love, D.; Worah, D.; Lim, K.

    1988-01-01

    The magnetic susceptibility mechanism for MR imaging contrast enhancement has the advantage of providing useful information, such as cerebral blood flow, without crossing the blood-brain barrier. In this paper the authors report the use of a highly effective, relatively nontoxic chelate as a magnetic susceptibility agent. Dy-DTPA-bis(methylamide) (Dy-DTPA-BMA) has an extremely low acute toxicity (LD-50, intravenous, mice ∼ 40 mmol/kg). Doses of 1 mmol/kg and 2 mmol/kg Dy-DTPA-BMA lowered the initial signal intensity 63% to 57%, respectively. The utility of this technique in detecting areas of reduced blood flow within the brain was demonstrated by imaging a rabbit with a cerebral perfusion deficit

  12. Estimating susceptibility and magnetization within the Earth's continental crust: Petrophysical and Satellite approaches

    Science.gov (United States)

    Purucker, M. E.; McEnroe, S. A.

    2014-12-01

    Magnetic models (Xchaos) made from Champ and Orsted data are used to place constraints on the average magnetic susceptibility and its variability in the continental crust. Estimates of magnetic crustal thickness are made in a two-step process. The first step uses a recent seismic model (Crust1.0) to estimate the thickness of crystalline crust above the Moho, modified in the Andes and the Himalayas to account for the non-magnetic lower crust there. The second step calculates the magnetic field expected from such a layer of crystalline rock assuming the magnetization is solely induced in the earth's main field by rock of constant magnetic susceptibility, and modifies the starting crustal thickness to bring it into agreement with the Xchaos model. This global model removes spherical harmonic degrees less than 15 to account for the core field mask. We restrict our attention to the continental crust, in particular to Australia, western North America, and Scandinavia. Petrophysical and petrological data from Scandinavian rocks that have been deep in the crust help place limits on susceptibility values. Our simulations use two susceptibilities, 0.02 and 0.04 SI. The mean crystalline crustal thickness from the seismic model is 42 and 37 km in western North America and Australia, respectively, and the modification with the magnetic data makes little change to the mean crustal thickness, irrespective of whether the susceptibility is 0.02 or 0.04 SI. However, the modification with the magnetic data does make a significant difference to the standard deviation of the crustal thickness, increasing it by a factor of two in the case of a susceptibility of 0.04, and by a factor of four in the case of a susceptibility of 0.02. The changes to the standard deviation of the crustal thickness are also evident in the Scandinavian data, but the mean crystalline crustal thickness of 45 km is significantly larger than that found from either magnetic model (33 and 30 km). The differences

  13. Characterization of tissue magnetic susceptibility-induced distortions for MRIgRT

    International Nuclear Information System (INIS)

    Stanescu, T.; Wachowicz, K.; Jaffray, D. A.

    2012-01-01

    Purpose: MR image geometric integrity is one of the building blocks of MRI-guided radiotherapy. In particular, tissue magnetic susceptibility-induced effects are patient-dependent and their behavior is difficult to assess and predict. In this study, the authors investigated in detail the characteristics of susceptibility (χ) distortions in the context of MRIgRT, including the case of two common MR-linac system configurations. Methods: The magnetic field distortions were numerically simulated for several imaging parameters and anatomical sites, i.e., brain, lung, pelvis (with air pockets), and prostate. The simulation process consisted of (a) segmentation of patient CT data into susceptibility relevant anatomical volumes (i.e., soft-tissue, bone and air/lung), (b) conversion of CT data into susceptibility masks by assigning bulk χ values to the structures defined at (a), (c) numerical computations of the local magnetic fields by using a finite difference algorithm, and (d) generation of the geometric distortion maps from the magnetic field distributions. For each patient anatomy, the distortions were quantified at the interfaces of anatomical structures with significantly different χ values. The analysis was performed for two specific orientations of the external main magnetic field (B 0 ) characteristic to the MR-linac systems, specifically along the z-axis for a bore MR scanner and in the (x,y)-plane for a biplanner magnet. The magnetic field local perturbations were reported in ppm. The metrics used to quantify the geometric distortions were the maximum, mean, and range of distortions. The numerical simulation algorithm was validated using phantom data measurements. Results: Susceptibility-induced distortions were determined for both quadratic and patient specific geometries. The numerical simulations showed a good agreement with the experimental data. The measurements were acquired at 1.5 and 3 T and with an encoding gradient varying between 3 and 20 mT/m by

  14. Characterization of tissue magnetic susceptibility-induced distortions for MRIgRT.

    Science.gov (United States)

    Stanescu, T; Wachowicz, K; Jaffray, D A

    2012-12-01

    MR image geometric integrity is one of the building blocks of MRI-guided radiotherapy. In particular, tissue magnetic susceptibility-induced effects are patient-dependent and their behavior is difficult to assess and predict. In this study, the authors investigated in detail the characteristics of susceptibility (χ) distortions in the context of MRIgRT, including the case of two common MR-linac system configurations. The magnetic field distortions were numerically simulated for several imaging parameters and anatomical sites, i.e., brain, lung, pelvis (with air pockets), and prostate. The simulation process consisted of (a) segmentation of patient CT data into susceptibility relevant anatomical volumes (i.e., soft-tissue, bone and air∕lung), (b) conversion of CT data into susceptibility masks by assigning bulk χ values to the structures defined at (a), (c) numerical computations of the local magnetic fields by using a finite difference algorithm, and (d) generation of the geometric distortion maps from the magnetic field distributions. For each patient anatomy, the distortions were quantified at the interfaces of anatomical structures with significantly different χ values. The analysis was performed for two specific orientations of the external main magnetic field (B(0)) characteristic to the MR-linac systems, specifically along the z-axis for a bore MR scanner and in the (x,y)-plane for a biplanner magnet. The magnetic field local perturbations were reported in ppm. The metrics used to quantify the geometric distortions were the maximum, mean, and range of distortions. The numerical simulation algorithm was validated using phantom data measurements. Susceptibility-induced distortions were determined for both quadratic and patient specific geometries. The numerical simulations showed a good agreement with the experimental data. The measurements were acquired at 1.5 and 3 T and with an encoding gradient varying between 3 and 20 mT∕m by using an annular

  15. Limits of out-of-phase susceptibility in magnetic granulometry of rocks and soils

    Czech Academy of Sciences Publication Activity Database

    Hrouda, F.; Pokorný, J.; Chadima, Martin

    2015-01-01

    Roč. 59, č. 2 (2015), s. 294-308 ISSN 0039-3169 Institutional support: RVO:67985831 Keywords : out-of-phase susceptibility * frequency-dependent susceptibility measurement accuracy * environmetal magnetism * loess * soil * paleoclimatic reconstruction Subject RIV: DE - Earth Magnetism , Geodesy, Geography Impact factor: 0.818, year: 2015

  16. Magnetic susceptibility measurement of solid oxygen at pressures up to 3.3 GPa

    Energy Technology Data Exchange (ETDEWEB)

    Mito, M., E-mail: mitoh@tobata.isc.kyutech.ac.jp; Yamaguchi, S.; Tsuruda, H.; Deguchi, H. [Faculty of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550 (Japan); Ishizuka, M. [Renovation Center of Instruments for Science Education and Technology, Osaka University, Toyonaka 560-8531 (Japan)

    2014-01-07

    The magnetic susceptibility of solid oxygen had long been observed only in the restricted pressure region below 0.8 GPa. We succeeded in extending the pressure region up to 3.3 GPa by clamping condensed oxygen in the sample chamber of a miniature diamond anvil cell and measuring the dc magnetic susceptibility using a superconducting quantum interference device magnetometer. In this experiment, the well-known α–β and β–γ transitions are observed in the phase diagram, suggesting consistency with the previous results of X-ray and Raman studies. In addition, a new magnetic anomaly is observed in the β phase.

  17. Upgrading of magnetic susceptibility of conodont sample residues before magnetic separation

    Czech Academy of Sciences Publication Activity Database

    Carls, P.; Slavík, Ladislav

    2005-01-01

    Roč. 38, č. 2 (2005), s. 171-172 ISSN 0024-1164. [Lethaia Seminar. Oslo , 15.06.2005] R&D Projects: GA AV ČR(CZ) KSK6005114 Keywords : magnetic susceptibility * heavy liquids * conodont concentration Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.562, year: 2005

  18. 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

  19. 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

  20. Influence of Radiation Damage and Isochronal Annealing on the Magnetic Susceptibility of Pu1-xAmx Alloys

    International Nuclear Information System (INIS)

    McCall, Scott K.; Fluss, Michael J.; Chung, Brandon W.; Haire, Richard G.

    2008-01-01

    Results of radiation damage in Pu and Pu 1-x Am x alloys studied with magnetic susceptibility, χ(T), and resistivity are presented. Damage accumulated at low temperatures increases χ(T) for all measured alloys, with the trend generally enhanced as the lattice expands. There is a trend towards saturation observable in the damage induced magnetic susceptibility data. that is not evident in similar damage induced resistivity data taken on the same specimen. A comparison of isochronal annealing curves measured by both resistivity and magnetic susceptibility on a 4.3 at% Ga stabilized δ-Pu specimen show that Stage I annealing, where interstitials begin to move, is largely transparent to the magnetic measurement. This indicates that interstitials have little impact on the damage induced increase in the magnetic susceptibility. The isochronal annealing curves of the Pu 1-x Am x alloys do not show distinct annealing stages as expected for alloys. However, samples near 20% Am concentration show an unexpected increase in magnetization beginning when specimens are annealed to 35 K. This behavior is also reflected in a time dependent increase in the magnetic susceptibility of damaged specimens indicative of first order kinetics. These results suggest there may be a metastable phase induced by radiation damage and annealing in Pu 1-x Am x alloys. (authors)

  1. Translation balance for measuring magnetic susceptibilities at high or low temperatures (1962)

    International Nuclear Information System (INIS)

    Blaise, A.; Peuch, M.A.

    1962-01-01

    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 -8 and 10 -4 u.e.m. C.G.S., can be measured. (authors) [fr

  2. Mapping Magnetic Susceptibility Anisotropies of White Matter in vivo in the Human Brain at 7 Tesla

    Science.gov (United States)

    Li, Xu; Vikram, Deepti S; Lim, Issel Anne L; Jones, Craig K; Farrell, Jonathan A.D.; van Zijl, Peter C. M.

    2012-01-01

    High-resolution magnetic resonance phase- or frequency- shift images acquired at high field show contrast related to magnetic susceptibility differences between tissues. Such contrast varies with the orientation of the organ in the field, but the development of quantitative susceptibility mapping (QSM) has made it possible to reproducibly image the intrinsic tissue susceptibility contrast. However, recent studies indicate that magnetic susceptibility is anisotropic in brain white matter and, as such, needs to be described by a symmetric second-rank tensor (χ¯¯). To fully determine the elements of this tensor, it would be necessary to acquire frequency data at six or more orientations. Assuming cylindrical symmetry of the susceptibility tensor in myelinated white matter fibers, we propose a simplified method to reconstruct the susceptibility tensor in terms of a mean magnetic susceptibility, MMS = (χ∥ + 2χ⊥)/3 and a magnetic susceptibility anisotropy, MSA = χ∥ − χ⊥, where χ∥ and χ⊥ are susceptibility parallel and perpendicular to the white matter fiber direction, respectively. Computer simulations show that with a practical head rotation angle of around 20°–30°, four head orientations suffice to reproducibly reconstruct the tensor with good accuracy. We tested this approach on whole brain 1×1×1 mm3 frequency data acquired from five healthy subjects at 7 T. The frequency information from phase images collected at four head orientations was combined with the fiber direction information extracted from diffusion tensor imaging (DTI) to map the white matter susceptibility tensor. The MMS and MSA were quantified for regions in several large white matter fiber structures, including the corona radiata, posterior thalamic radiation and corpus callosum. MMS ranged from −0.037 to −0.053 ppm (referenced to CSF being about zero). MSA values could be quantified without the need for a reference and ranged between 0.004 and 0.029 ppm, in line with

  3. Magnon heat capacity and magnetic susceptibility of the spin Lieb lattice

    Energy Technology Data Exchange (ETDEWEB)

    Yarmohammadi, Mohsen, E-mail: m.yarmohammadi69@gamil.com

    2016-11-01

    Using linear response theory, Heisenberg model Hamiltonian and Green's function technique, the influences of Dzyaloshinskii–Moriya interaction (DMI), external magnetic field and next-nearest-neighbor (NNN) coupling on the density of magnon modes (DMM), the magnetic susceptibility (MS) and the magnon heat capacity (MHC) of a spin Lieb lattice, a face-centered square lattice, are investigated. The results reveal a band gap in the DMM and 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 ferromagnetism in spin Lieb-based nanosystems, MS is investigated. Further, we report a Schottky anomaly in the MHC. The results show that the effects of the magnetic field on the MHC and MS have different behaviors in two temperature regions. In the low temperature region, MHC and MS increase when the magnetic field strength increases. On the other hand, the MHC and MS reduce with increasing the magnetic field strength in the high temperature region. Also comprehensive numerical modelling of the DMM, the MS and the MHC of a spin Lieb lattice yields excellent qualitative agreement with the experimental data. - Highlights: • Theoretical calculation of density of states of the spin Lieb lattice. • The investigation of the effect of external magnetic field on the magnon heat capacity and magnetic susceptibility. • The investigation of the effect of NNN coupling and the DMI strength on the magnon heat capacity and magnetic susceptibility.

  4. Method of magnetic susceptibility mapping of drilled cores. Experimental measurements for geologic structures determination

    International Nuclear Information System (INIS)

    Delrive, C.

    1993-01-01

    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 -5 SI units and can generate magnetic susceptibility maps with 4 x 4 mm 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

  5. Magnetic susceptibility of Gd/sub 3/Ga/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Hacker, H Jr; Gupta, R M [Duke Univ., Durham, N.C. (USA). Dept. of Electrical Engineering

    1976-03-01

    The magnetic susceptibility of the intermetallic compound Gd/sub 3/Ga/sub 2/ has been measured by the Faraday method over the range 8 - 300 K. The data indicate antiferromagnetic behavior below 53 K. Above 100 K, the mass susceptibility obeys the Curie-Weiss law, chisub(g)=4.45X10/sup -2//(T+23)emu/gOe. The corresponding effective moment is 8.51 Bohr magnetons.

  6. Magnetic hysteresis and complex susceptibility as measures of ac losses in a multifilamentary NbTi superconductor

    International Nuclear Information System (INIS)

    Goldfarb, R.B.; Clark, A.F.

    1985-01-01

    Magnetization and ac susceptibility of a standard NbTi superconductor were measured as a function of longitudinal dc magnetic field. The ac-field-amplitude and frequency dependences of the complex susceptibility are examined. The magnetization is related to the susceptibility by means of a theoretical derivation based on the field dependence of the critical current density. Hysteresis losses, obtained directly from dc hysteresis loops and derived theoretically from ac susceptibility and critical current density, were in reasonable agreement

  7. Continuous Real-time Measurements of Vertical Distribution of Magnetic Susceptibility In Soils

    Science.gov (United States)

    Petrovsky, E.; Hulka, Z.; Kapicka, A.; Magprox Team

    Measurements of top-soil magnetic susceptibility are used in approximative outlining polluted areas. However, one of the serious limitations of the method is discrimina- tion between top-soil layers enhanced by atmospherically deposited anthropogenic particles from those dominated by natural particles migrating from magnetically-rich basement rocks. For this purpose, measurements of vertical distribution of magnetic susceptibility along soil profiles is one of the most effective ways in estimating the effect of lithogenic contribution. Up to now, in most cases soil cores have to be mea- sured in laboratory. This method is quite time consuming and does not allow flexible decision about the suitability of the measured site for surface magnetic mapping. In our contribution we will present a new device enabling continuous real-time measure- ments of vertical distribution of magnetic susceptibility directly in field, performed in holes after soil coring. The method is fast, yielding smooth curves (6 data points per 1 mm dept), at least as sensitive as laboratory methods available until now, and at- tached notebook enables direct, on-line control of the lithogenic versus anthropogenic contributions.

  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. Anisotropy of susceptibility in rocks which are magnetically nonlinear even in low fields

    Science.gov (United States)

    Hrouda, František; Chadima, Martin; Ježek, Josef

    2018-06-01

    Theory of the low-field anisotropy of magnetic susceptibility (AMS) assumes a linear relationship between magnetization and magnetizing field, resulting in field-independent susceptibility. This is valid for diamagnetic and paramagnetic minerals by definition and also for pure magnetite, while in titanomagnetite, pyrrhotite and hematite the susceptibility may be clearly field-dependent even in low fields used in common AMS meter. Consequently, the use of the linear AMS theory is fully legitimate in the former minerals, but in principle incorrect in the latter ones. Automated measurement of susceptibility in 320 directions in variable low-fields ranging from 5 to 700 A m-1 was applied to more than 100 specimens of various pyrrhotite-bearing and titanomagnetite-bearing rocks. Data analysis showed that the anisotropic susceptibility remains well represented by an ellipsoid in the entire low-field span even though the ellipsoid increases its volume and eccentricity. The principal directions do not change their orientations with low-field in most specimens. Expressions for susceptibility as a function of field were found in the form of diagonal tensor whose elements are polynomials of low order. In a large proportion of samples, the susceptibility expressions can be further simplified to have one common skeleton polynomial.

  10. Magnetic susceptibility measurement using 3D NMR

    Czech Academy of Sciences Publication Activity Database

    Marcon, P.; Bartušek, Karel; Kořínek, Radim

    2011-01-01

    Roč. 24, Suppl. 1 (2011), s. 381-382 ISSN 0968-5243. [ESMRMB 2011 Congress. 06.10.2011-08.10.2011, Leipzig] R&D Projects: GA ČR GAP102/11/0318 Institutional research plan: CEZ:AV0Z20650511 Keywords : MRI * artifact correction * magnetic susceptibility * gradient echo Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  11. Analysis of the magnetic susceptibility well log in drill hole UE25a-5, Yucca Mountain, Nevada Test Site

    International Nuclear Information System (INIS)

    Hagstrum, J.T.; Daniels, J.J.; Scott, J.H.

    1980-01-01

    Magnetic susceptibility measurements have been shown to be dependent upon the magnetite content of rocks with variations in rock susceptibility arising from changes in the shape, size, composition, and quantity of the contained magnetite grains. The present study was undertaken to determine the factor(s) responsible for the variation in magnetic susceptibility measurements from borehole UE25a-5 on the Nevada Test Site (NTS). The well logs and sample analyses presented in this paper form part of a larger geophysical well-logging project studying the physical properties of welded tuffs at NTS. The ash-flow sheets at NTS appear to be the products of single compositionally zoned magmas that tend, within a cooling unit, to erupt hotter, more mafic, and more crystal-rich with time. These factors, however, have little effect on the degree to which the tuffs become welded. Furthermore, zones of crystallization and alteration are superimposed upon the welded units. X-ray data show poor correspondence between the relative abundance of magnetite in a sample and the borehole magnetic susceptibility measurement associated with it. Curie balance experiments demonstrate no change in the magnetic mineralogy that could account for the susceptibility variation. Thin-section observations corroborate the x-ray data, but indicate a proportional relationship between the borehole susceptibility measurements and the grain-size distribution of magnetite. The association of magnetic susceptibility anomalies with the crystal-rich zones of the welded tuffs will aid in the identification and correlation of the eruptive sequences at NTS

  12. Magnetic susceptibility of functional groups

    International Nuclear Information System (INIS)

    Herr, T.; Ferraro, M.B.; Contreras, R.H.

    1990-01-01

    Proceeding with a series of works where new criteria are applied to the the calculation of the contribution of molecular fragments to certain properties, results are presented for a group of 1-X-benzenes and 1-X-naphtalenes for the magnetic susceptibility constant. Both the diamagnetic and paramagnetic parts are taken into account. To reduce the problems associated with the Gauge dependence originated in the approximations made, Gauge independent atomic orbitals (GIAO) orbitals are used in the atomic orbital basis. Results are discussed in terms of functional groups. (Author). 17 refs., 1 fig., 3 tabs

  13. Review of magnetic susceptibility logging and its application to uranium exploration

    International Nuclear Information System (INIS)

    George, D.C.; Scott, J.H.

    1982-01-01

    Borehole measurement of magnetic susceptibility can show anomalies associated with mineralization or alteration. The detection of small anomalies is necessary, so efforts have been made in recent years to improve the sensitivity and the stability of magnetic susceptibility logging tools. Typical tools contain a single coil constructed as a solenoid wound on ferrite rods about 30cm long. The coil is heated to a constant temperature to reduce drift, and careful design is necessary to optimize temperature control and to maximize sensitivity. Measurements of coil resistance and inductance, which indicate conductivity and susceptibility, are made using a Maxwell bridge circuit. Circuit analysis shows that conductivity measurements are difficult and that stringent requirements are placed on phase stability of measurement circuitry. Corrections to the observed log are necessary to account for borehole size. The response of the tool to a thin zones of anomalous susceptibility is double peaked and a set of curves has been developed for interpretation. Calibrations of the tools are made by measuring the tool's response in models of known susceptibility

  14. Magnetic susceptibility of transition metal alloys with a hcp structure

    International Nuclear Information System (INIS)

    Volkenshtejn, N.V.; Galoshina, Eh.V.; Gorina, N.B.; Korenovskij, N.L.; Polyakova, V.P.; Savitskij, E.M.

    1978-01-01

    The angular dependence of the magnetic susceptibility of single crystals of Ru-Nb, Re-W and Os-Re alloys is investigated in the region of the hexagonal closely packed structure. The spin susceptibility is estimated on the basis of available data on the electron specific heat. The principal values of the orbital component of the susceptibility are determined under the assumption of isotopy of the spin contribution to the susceptibility. In Ru-Nb alloys the magnitudes of the orbital contributions and the susceptibility anisotropy are found to increase; in Re-W the spin contribution is noticeably greater whereas the orbital susceptibility is smaller, as is the anistropy. In the Os-Re alloy the orbital contributions increase and the susceptibility anisotropy is constant. It is suggested that the addition of the second component changes the overlapping of the d-electron wave functions

  15. Disk-cylinder method for using NMR to measure magnetic susceptibility

    International Nuclear Information System (INIS)

    Burnham, A.K.

    1978-01-01

    The sphere-cylinder method of using nuclear magnetic resonance (NMR) to measure the magnetic susceptibility of diamagnetic and paramagnetic materials has been generalized to the disk-cylinder method. A two-fold increase in sensitivity was obtained. Accuracies of 0.1% of the diamagnetism of water should be readily obtainable

  16. Atom-vacancy ordering and magnetic susceptibility of nonstoichiometric hafnium carbide

    International Nuclear Information System (INIS)

    Gusev, A.I.; Zyryanova, A.N.

    1999-01-01

    Experimental results on magnetic susceptibility of nonstoichiometric hafnium carbide HfC y (0.6 0.71 , HfC 0.78 and HfC 0.83 in the range of 870-930 K the anomalies are revealed which are associated with superstructure short-range ordering in a non-metallics sublattice. It is shown that a short-range order in HfC 0.71 and HfC 0.78 carbides corresponds to Hf 3 C 2 ordered phase, and in HfC 0.83 carbide - to Hf 6 C 5 ordered phase. HfC 0.78 carbide is found to possesses zero magnetic susceptibility in temperature range 910-980 K [ru

  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 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.

  19. Synthesis and magnetic hyperthermia studies on high susceptible Fe1-xMgxFe2O4 superparamagnetic nanospheres

    Science.gov (United States)

    Manohar, A.; Krishnamoorthi, C.

    2017-12-01

    Majority studies on magnetic hyperthermia properties were carried out by modifying the saturation mass magnetization (Ms) of the samples. Here efforts were made to enhance the specific heat generation rate (SHGR) of single domain superparamagnetic (SP) material by modifying its magnetic susceptibility. Well crystallined, inverse spinel structured and close to monosize Fe1-xMgxFe2O4 (x = 0, 0.1, 0.2, 0.3, 0.4, & 0.5) compounds with nanosphere geometry (diameter 10 nm) were synthesized by solvothermal reflux method at ≈ 300 °C . In the literature it is reported that magnesium ferrites synthesized at high temperatures yield mixed (normal & inverse) spinel structures. The inverse spinel structure was confirmed by X-ray powder diffraction (XRPD), lattice vibrations and magnetic characteristics of the compounds. The Ms of the compounds decrease with increase of substituent Mg2+ concentration. Under high excitation energy the inter-valance charge transfer whereas under low excitation energy the intra-valance charge transfer process were predominant. The as-synthesized nanospheres were encapsulated by hydrophobic oleic acid and were exchanged by hydrophilic poly(acrylic acid) by chemical exchange process. Estimated magnetic hyperthermia power or SHGR of the x = 0, 0.3 & 0.5 were 11, 11.4 & 22.4 W per gram of respective compounds, respectively, under 63.4 kA m-1 field amplitude and 126 kHz frequency. The SHGR enhances with Mg2+ concentration though its Ms reduces and is attributed to reduced spin-orbital coupling in the compounds with enhanced Mg2+ concentration. This may pave a new way to develop magnetic hyperthermia material by modifying magnetic susceptibility of the compounds against to the reported Ms modification approach. The obtained high SHGR of the biocompatible compounds could be used in magnetic hyperthermia applications in biomedical field.

  20. Magnetic susceptibility of one-dimensional ferromagnetic CsFeCl3 crystals

    International Nuclear Information System (INIS)

    Tsuboi, T.; Chiba, M.

    1989-01-01

    The parallel and perpendicular magnetic susceptibilities of one-dimensional ferromagnetic CsFeCl 3 crystals have been calculated from magnetization measured as a function of temperature in the range 0 to 70 K by means of a superconducting quantum interference device (SQUID). The experimental results have been compared with data from the literature for other Cs-and Rb-containing crystals with ferromagnetic or antiferromagnetic linear chains. Reliable values of the exchange and anisotropy energies can be estimated from experimental susceptibility data using theoretical g-values and the dynamical correlated-effective field approximation

  1. Study of amorphous semiconductors doped with rare earths (Gd and Er) and conducting polymers by EPR techniques and magnetic susceptibility

    International Nuclear Information System (INIS)

    Sercheli, Mauricio da Silva

    1999-01-01

    This thesis involves the study of amorphous semiconductors and conducting polymers, which have been characterized by EPR and magnetic susceptibility measurements, and to a lesser extent by Raman spectroscopy and RBS. The semiconductors were studied using thin films of silicon doped with rare earth metals, e.g. erbium and gadolinium, which had their magnetic properties studied. Using these studies we could determine the state of valence of the rare earths as well as their concentrations in the silicon matrix. According to our results, the valence of the rare earth metal ions is 3+, and we were able to conclude that 4f electronic shells could not be used for the calculation of the conducting band in this system. Furthermore, the analysis of the data on the magnetic susceptibility of the Er 3+ ion with cubic crystalline acting field, gave us the opportunity to estimate the overall splitting of their electronic states for the first time. The conducting polymers were studied using samples of poly(3-methylthiophene) doped with ClO 4 - , which show a phase transition in the range of 230 K to 130 K. The electron paramagnetic resonance also gives important information on the crystallization, doping level and the presence of polarons or bipolarons in conducting polymers. (author)

  2. Magnetic susceptibilities of Ca/sub y/U/sub 1-y/O/sub 2+x/ solid solutions

    International Nuclear Information System (INIS)

    Hinatsu, Y.; Fujino, T.

    1988-01-01

    Magnetic susceptibilities of Ca/sub y/U/sub 1-y/O/sub 2+x/ solid solutions with fluorite structure were measured from 4.2 K to room temperature. An antiferromagnetic transition was observed for all the solid solutions examined in this study (y ≤ 0.33). The Neel temperature of the oxygen-hypostoichiometric solid solutions (x 2 solid solutions, but different from that of (U,Th)O 2 solid solutions. The effective magnetic moment decreased with increasing calcium concentration, which indicates the oxidation of uranium in the solid solutions. From the analysis of the magnetic susceptibility data, it was found that the oxidation state of uranium was either tetravalent or pentavalent. The Neel temperature of the hyperstoichiometric solid solutions (x > 0) did not change appreciably with calcium concentrations. From the comparison of the magnetic susceptibility data of the hypostoichiometric solid solutions with those of the hyperstoichiometric solid solutions, the effect of oxygen vacancies is more significant than that of interstitial oxygens on the decrease of magnetic interactions between uranium ions

  3. Magnetic susceptibility of CoFeBSiNb alloys in liquid state

    Energy Technology Data Exchange (ETDEWEB)

    Sidorov, V., E-mail: vesidor@mail.ru [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Hosko, J. [Institute of Physics SAS, Bratislava (Slovakia); Mikhailov, V.; Rozkov, I.; Uporova, N. [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Svec, P.; Janickovic, D.; Matko, I.; Svec Sr, P. [Institute of Physics SAS, Bratislava (Slovakia); Malyshev, L. [Ural Federal University, Ekaterinburg (Russian Federation)

    2014-03-15

    The influence of small additions of gallium and antimony on magnetic susceptibility of the bulk glass forming Co{sub 47}Fe{sub 20.9}B{sub 21.2}Si{sub 4.6}Nb{sub 6.3} alloy was studied in a wide temperature range up to 1830 K by the Faraday’s method. The undercooling for all the samples was measured experimentally. Both Ga and Sb additions were found to increase liquidus and solidification temperatures. However, gallium atoms strengthen interatomic interaction in the melts, whereas antimony atoms reduce it. - Highlights: • Bulk metallic glasses from CoFeBSiNb-based alloys were produced as in situ composites. • Magnetic susceptibility of these alloys was measured in a wide temperature range including liquid state. • Undercooling of these melts was measured experimentally. • Ga additions strengthen interatomic interaction in BMG melts, whereas Sb atoms reduce it.

  4. Evolution of fabric in Chitradurga granite (south India) - A study based on microstructure, anisotropy of magnetic susceptibility (AMS) and vorticity analysis

    Science.gov (United States)

    Mondal, Tridib Kumar

    2018-01-01

    In this paper, the fabric in massive granite ( 2.6 Ga) from the Chitradurga region (Western Dharwar Craton, south India) is analyzed using microstructure, anisotropy of magnetic susceptibility (AMS) study and kinematic vorticity analysis. The microstructural investigation on the granite shows a progressive textural overprint from magmatic, through high-T to low-T solid-state deformation textures. The mean magnetic foliation in the rocks of the region is dominantly NW-SE striking which have developed during regional D1/D2 deformation on account of NE-SW shortening. The plunge of the magnetic lineation varies from NW to vertical to SE, and interpreted to be a consequence of regional D3 deformation on account of NW-SE to E-W shortening. The vorticity analysis from magnetic fabric in the region reveals that the NW-SE oriented fabric formed under pure shear condition during D1/D2 regional deformation. However, some parts of the region particularly close to the adjacent Chitradurga Shear Zone show that the magnetic fabrics are oblique to the foliation as well as shear zone orientation and inferred to be controlled by simple shearing during D3 regional deformation. The shape preferred orientation (SPO) analysis from oriented thin sections suggest that the shape of the recrystallized quartz grains define the magnetic fabric in Chitradurga granite and the degree of the SPO reduces away from the Chitradurga Shear Zone. It is interpreted that the change in magnetic fabrics in some parts of the granite in the region are dominantly controlled by the late stage sinistral shearing which occurred during the development of Chitradurga Shear Zone. Anisotropy of magnetic susceptibility (AMS) data of granite from the Chitradurga region (West Dharwar Craton, southern India). Km = Mean susceptibility; Pj = corrected degree of magnetic anisotropy; T = shape parameter. K1 and K3 are the maximum and minimum principal axes of the AMS ellipsoid, respectively. dec = Declination; inc

  5. Viscosity of magnetic fluids must be modified in calculations of dynamic susceptibility

    Energy Technology Data Exchange (ETDEWEB)

    Lebedev, A.V., E-mail: lav@icmm.ru

    2017-06-01

    The frequency dependences of dynamic susceptibility were measured for a series of magnetic fluid samples with the same dispersed composition at different temperatures. Coincidence of normalized dynamic susceptibility curves plotted for different concentrations was obtained only after introducing correction for the value of dynamic viscosity of the magnetic fluid. The value of the correction coefficient doesn’t depend on temperature and is the universal function of the hydrodynamic concentration of particles. - Highlights: • Dynamic susceptibility was measured at different temperatures and concentrations. • Coincidence of curves requires a correction of value of viscosity in calculations. • This correction is function of the hydrodynamic concentration of particles. • With this function the rotation of particles are described correctly.

  6. Effect of tensile stress on the 3D reversible and irreversible differential magnetic susceptibilities

    International Nuclear Information System (INIS)

    Mao, Weihua; Atherton, David L.

    2001-01-01

    Magnetic hysteresis loops in three orthogonal directions are measured for a line pipe steel sample while the external magnetic field is applied in a direction perpendicular to the tensile stress direction. The total magnetization vector is calculated. This tends to the stress direction when tensile stress is applied. The reversible and irreversible differential magnetic susceptibilities are derived. It is found that the susceptibilities in all three directions are enhanced with increasing tensile stress, although the increase in the stress direction is much larger than in the other directions. [copyright] 2001 American Institute of Physics

  7. Diagenetic versus detrital origin of the magnetic susceptibility variations in some carbonate Frasnian-Famennian boundary sections from Northern Africa and Western Europe: implications for paleoenvironmental reconstructions

    Science.gov (United States)

    Riquier, Laurent; Averbuch, Olivier; Devleeschouwer, Xavier; Tribovillard, Nicolas

    2010-10-01

    To provide a new insight into the diagenetic versus detrital origin of the magnetic susceptibility variations in ancient carbonate sequences, a study was conducted within four Frasnian-Famennian platform carbonate sections from Germany, France and Morocco. The study includes along-section magnetic susceptibility and carbonate content measurements complemented by analyses of magnetic hysteresis parameters, inorganic geochemistry and clay mineralogy. Our results show that the magnetic susceptibility evolution is dominantly controlled by the variations in the concentration of low-coercivity ferromagnetic magnetite grains and, to a lesser extent, of paramagnetic clays. In more detail, hysteresis ratios suggest the coexistence of two magnetite populations with significantly different grain size: (1) a dominantly coarse-grained detrital fraction including a mixture of multi-domain and single-domain particles (2) an authigenic fine-grained fraction composed of a mixture of single-domain and superparamagnetic particles. Despite a diagenetic imprint on the clay assemblages, no relationship is established between magnetic susceptibility and illite crystallinity, therefore discarding a noticeable distortion of primary within-section magnetic susceptibility evolution. The overall inherited character of the magnetic susceptibility fluctuations is corroborated by a significant correlation of magnetic susceptibility with terrigenous proxies (Zr, Th). The poorer correlation of magnetic susceptibility with the Fe content is consistent with the existence of a very fine-grained authigenic magnetite component that possibly induces a global magnetic susceptibility increase at the section scale, but no distortion of the within-section evolution. The magnetic susceptibility curves presented here provide a general record of climate-driven detrital influx and carbonate productivity through Frasnian-Lower Famennian times.

  8. 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

  9. Tensor of effective susceptibility in random magnetic composites: Application to two-dimensional and three-dimensional cases

    Science.gov (United States)

    Posnansky, Oleg P.

    2018-05-01

    The measuring of dynamic magnetic susceptibility by nuclear magnetic resonance is used for revealing information about the internal structure of various magnetoactive composites. The response of such material on the applied external static and time-varying magnetic fields encodes intrinsic dynamic correlations and depends on links between macroscopic effective susceptibility and structure on the microscopic scale. In the current work we carried out computational analysis of the frequency dependent dynamic magnetic susceptibility and demonstrated its dependence on the microscopic architectural elements while also considering Euclidean dimensionality. The proposed numerical method is efficient in the simulation of nuclear magnetic resonance experiments in two- and three-dimensional random magnetic media by choosing and modeling the influence of the concentration of components and internal hierarchical characteristics of physical parameters.

  10. Modified thermogravimetric apparatus to measure magnetic susceptibility on-line during annealing of metastable ferromagnetic materials

    International Nuclear Information System (INIS)

    Luciani, G.; Constantini, A.; Branda, F.; Ausanio, G.; Hison, C.; Iannotti, V.; Luponio, C.; Lanotte, L.

    2004-01-01

    The insertion of proper coils to generate a magnetic field, with controlled gradient, in a standard thermogravimetric apparatus is shown to be a valid solution to measure on-line, upon heat treatment, the magnetic susceptibility in ribbon shaped samples of a metastable ferromagnetic material. The method is very useful to individuate the annealing conditions that optimise soft or hard magnetic properties without using separate apparatuses for heat treatment, control of the structural phase transition and characterization of magnetic susceptibility

  11. Integrated geophysical characterisation of Sunyani municipal solid waste disposal site using magnetic gradiometry, magnetic susceptibility survey and electrical resistivity tomography

    Science.gov (United States)

    Appiah, Isaac; Wemegah, David Dotse; Asare, Van-Dycke Sarpong; Danuor, Sylvester K.; Forson, Eric Dominic

    2018-06-01

    Non-invasive geophysical investigation using magnetic gradiometry, magnetic susceptibility survey and electrical resistivity tomography (ERT) was carried out on the Sunyani Municipal Assembly (SMA) solid waste disposal (SWD) site. The study was aimed at delineating the physical boundaries and the area extent of the waste deposit, mapping the distribution of the waste at the site, detecting and delineating zones of leachate contamination and its preferential migration pathways beneath the waste deposit and its surroundings. The results of both magnetic susceptibility and gradiometric methods displayed in anomaly maps clearly delineated the physical boundaries of the waste deposit with an approximate area extent of 82,650 m2 that are characterised by high magnetic susceptibilities between 426 × 10-5 SI and 9890 × 10-5 SI. They also revealed high magnetic anomalies erratically distributed within the waste deposit attributable to its heterogeneous and uncontrolled nature. The high magnetic anomalies outside the designated waste boundaries were also attributed to indiscriminate deposition of the waste. Similarly, the ERT sections delineated and characterised zones of leachate contamination beneath the waste body and its close surroundings as well as pathways for leachate migration with low resistivity signatures up to 43.9 Ωm. In spite of the successes reported herein using the ERT, this research also revealed that the ERT is less effective in estimating the thickness of the waste deposit in unlined SWD sites due to leachate infiltration into the ground beneath it that masks the resistivities of the top level ground and makes it indistinguishable from the waste body.

  12. Perfusion imaging with magnetic-susceptibility contrast media

    International Nuclear Information System (INIS)

    Rosen, B.R.; Belliveau, J.W.; Betteridge, D.; Cohen, M.S.; Weisskoff, R.M.; Vevea, J.M.; Rzedzian, R.P.; Brady, T.J.

    1989-01-01

    In animal models, transient signal los on T2-weighted images has been well documented following intravenous injection of high-magnetic-susceptibility contrast agents that are compartmentalized within the brain intravascular space. These signal changes have been correlated with physiologic parameters, such as blood flow and volume. The advent of whole-body single-shot imaging capability, coupled with the approval of paramagnetic contrasts agents for human use, has enabled the authors to demonstrate susceptibility contrast in the human brain, allowing for generation of functional images. With use of a 1.5-T imaging system gradient-echo images (TE = 60 msec) were acquired in 75 msec. Sequential single-sections images were sampled every 1 second following bolus administration of 0.1 mmol/kg of Gd-DTPA

  13. Anisotropy of susceptibility in rocks that are magnetically non-linear even in weak fields

    Czech Academy of Sciences Publication Activity Database

    Chadima, Martin; Ježek, J.; Hrouda, F.

    2017-01-01

    Roč. 19, EGU General Assembly 2017 (2017) ISSN 1029-7006. [European Geosciences Union General Assembly. 23.04.2017-28.04.2017, Vienna] Institutional support: RVO:67985831 Keywords : anisotropy of magnetic susceptibility * field-dependent susceptibility * second-rank tensor Subject RIV: DE - Earth Magnetism, Geodesy, Geography http://meetingorganizer.copernicus.org/EGU2017/EGU2017-7210-1.pdf

  14. Influence of oxygen disordering on static magnetic susceptibility of YBa2Cu3O7-x ceramics

    International Nuclear Information System (INIS)

    Sokolov, B.Yu.; Vil'danov, R.R.

    2008-01-01

    Influence of disordering of the populated oxygen positions in YBa 2 Cu 3 O 7-x ceramic's structure on its static magnetic susceptibility in the range of temperatures T>Tc is investigated. For occurrence of disordering the initial ceramics YBa 2 Cu 3 O 6,9 was annealed at T=520 C with the subsequent quenching in liquid nitrogen. Evolutions of a magnetic susceptibility and resistance of annealed ceramics during its air storage at a room temperature were studied. It is revealed that, unlike the initial optimum doped ceramics, annealed samples have appreciable temperature dependence of a magnetic susceptibility. Interpretation of results is executed on the basis of model of electronic phase separation and occurrence of a pseudo gap in a energy spectrum of free carriers of a superconductor. (authors)

  15. 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

  16. Magnetic susceptibility, specific heat and magnetic structure of CuNi2(PO4)2

    International Nuclear Information System (INIS)

    Escobal, Jaione; Pizarro, Jose L.; Mesa, Jose L.; Larranaga, Aitor; Fernandez, Jesus Rodriguez; Arriortua, Maria I.; Rojo, Teofilo

    2006-01-01

    The CuNi 2 (PO 4 ) 2 phosphate has been synthesized by the ceramic method at 800 deg. C in air. The crystal structure consists of a three-dimensional skeleton constructed from MO 4 (M II =Cu and Ni) planar squares and M 2 O 8 dimers with square pyramidal geometry, which are interconnected by (PO 4 ) 3- oxoanions with tetrahedral geometry. The magnetic behavior has been studied on powdered sample by using susceptibility, specific heat and neutron diffraction data. The bimetallic copper(II)-nickel(II) orthophosphate exhibits a three-dimensional magnetic ordering at, approximately, 29.8 K. However, its complex crystal structure hampers any parametrization of the J-exchange parameter. The specific heat measurements exhibit a three-dimensional magnetic ordering (λ-type) peak at 29.5 K. The magnetic structure of this phosphate shows ferromagnetic interactions inside the Ni 2 O 8 dimers, whereas the sublattice of Cu(II) ions presents antiferromagnetic couplings along the y-axis. The change of the sign in the magnetic unit-cell, due to the [1/2, 0, 1/2] propagation vector determines a purely antiferromagnetic structure. - Graphical abstract: Magnetic structure of CuNi2(PO4)2

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

    Energy Technology Data Exchange (ETDEWEB)

    Landi, Gabriel T., E-mail: gtlandi@gmail.com [Universidade Federal do ABC, 09210-580 Santo André (Brazil); Arantes, Fabiana R. [Universidade Federal do ABC, 09210-580 Santo André (Brazil); Cornejo, Daniel R. [Instituto de Física da Universidade de São Paulo, São Paulo 05508-090 (Brazil); Bakuzis, Andris F. [Instituto de Física, Universidade Federal de Goiás, 74690-900 Goiânia-GO (Brazil); Andreu, Irene; Natividad, Eva [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Zaragoza 50018 (Spain)

    2017-01-01

    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 within 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 information regarding the influence of the dipolar interaction in a sample. We develop a model which includes both aspects of the dipolar interaction and may be fitted directly to the susceptibility data. The usual long-range nature of the interaction is implemented using a mean-field approximation, whereas the particle-particle aggregation is modeled using a distribution of anisotropy constants. The model is then applied to two samples studied at different concentrations. One consists of spherical magnetite nanoparticles dispersed in oil and the other of cubic magnetite nanoparticles embedded on polymeric nanospheres. We also introduce a simple technique to address the presence of the dipolar interaction in a given sample, based on the height of the AC susceptibility peaks for different driving frequencies. - Highlights: We discuss the importance of the dipolar interaction in magnetic nanoparticle samples. It is shown that AC susceptibility may be used to estimate the extent of this interaction. We develop a model that accounts for particle aggregation. The theoretical model is then fitted to distinct magnetite samples.

  18. Magnetic susceptibilities of bynary non-electrolyte mixtures

    International Nuclear Information System (INIS)

    Caceres, P.; Acevedo, I.L.; Postigo, M.A.; Kartz, M.

    1987-01-01

    Molar magnetic susceptibilities are determined by the Goy method for the following two systems: 1-propanol + methyl acetate and 2-propanol + methyl acetate at 298 K where the three molecules are polar and the alcohol molecules are associated in their pure state. Excess diamagnetic susceptibilties are calculated to obtain information about possible interactions. Diamagnetic suscetibilities were related with molecular polarizabilities by Boyer-Donzelot's equation and compared with experimental results. (author) [pt

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

    International Nuclear Information System (INIS)

    Vannette, Matthew Dano

    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, ?, 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 ? 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 ? 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.

  20. Electric susceptibility of a magnetized plasma under electromagnetically induced transparency

    International Nuclear Information System (INIS)

    Kawamori, E

    2011-01-01

    This study derives the electric susceptibility tensor of a cold magnetized plasma under electromagnetically induced transparency (EIT) regime (Litvak and Tokman 2002 Phys. Rev. Lett. 88 095003, Shvets and Wurtele 2002 Phys. Rev. Lett. 89 115003) in which an intense right-hand circularly polarized pump wave is injected parallel to the background magnetic field. A dispersion relation of the wave in the electron cyclotron frequency range for an arbitrary propagation angle is obtained from this susceptibility tensor. In the case of purely parallel propagation of the probe wave, the dispersion relation obtained by Litvak, Shvets and others is recaptured. A new finding is that a stop band emerges between left-hand cutoff and upper hybrid frequencies, in which originally an extraordinary-mode (X) branch exists, in the case of perpendicular propagation to the background magnetic field under the EIT. The bandwidth of the stop band expands as the pump wave is intensified. For the situation of launching the probe wave from the high-field side in a tokamak, the accessibility of the probe wave to the region where the EIT effect appears is investigated. The EIT region which is a resonance layer created by the EIT is accessible to the probe wave, indicating the possibility of the application of EIT to control the spatial position of wave power deposition.

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

    African Journals Online (AJOL)

    Introduction: Susceptibility-weighted imaging (SWI) is a new method in MR imaging. SWI detects the signal loss created by disturbance of a homogeneous magnetic field; these disturbances can be caused by paramagnetic, ferromagnetic, or diamagnetic substances. There are many neurologic conditions that can benefit ...

  3. Detection of the pedogenic magnetic fraction in volcanic soils developed on basalts using frequency-dependent magnetic susceptibility: comparison of two instruments

    Science.gov (United States)

    Grison, Hana; Petrovsky, Eduard; Kapicka, Ales; Hanzlikova, Hana

    2017-05-01

    In studies of the magnetic properties of soils, the frequency-dependent magnetic susceptibility percentage (χFD%) is often used for the identification of ultrafine magnetically superparamagnetic/stable single-domain (SP/SSD) particles. This parameter is commonly used as an indicator for increased pedogenesis. In strongly magnetic soils, the SP/SSD magnetic signal (mostly bio-pedogenic) may be masked by lithological signals; making pedogenesis hard to detect. In this study, we compare results for the detection of ultrafine SP/SSD magnetic particles in andic soils using two instruments: a Bartington MS2B dual-frequency meter and an AGICO Kappabridge MFK1-FA. In particular, the study focuses on the effect of pedogenesis by investigating the relationship between specific soil magnetic and chemical properties (soil organic carbon and pHH2O). The values of χFD% obtained with the MS2B varied from 2.4 to 5.9 per cent, and mass-specific magnetic susceptibility (χLF) from 283 to 1688 × 10-8 m3 kg-1, while values of χFD% and χLF obtained with the MFK1-FA varied from 2.7 to 8.2 per cent and from 299 to 1859 × 10-8 m3 kg-1, respectively. Our results suggest that the detection of the SP/SSD magnetic fraction can be accomplished by comparing relative trends of χFD% along the soil profile. Moreover, the discrimination between bio-pedogenic and lithogenic magnetic contributions in the SP/SSD fraction is possible by comparing the χFD% and χLF data determined in the fine earth (<2 mm) and the coarse fraction (4-10 mm) samples down the soil profile.

  4. Magnetic susceptibility of road deposited sediments at a national scale – Relation to population size and urban pollution

    International Nuclear Information System (INIS)

    Jordanova, Diana; Jordanova, Neli; Petrov, Petar

    2014-01-01

    Magnetic properties of road dusts from 26 urban sites in Bulgaria are studied. Temporal variations of magnetic susceptibility (χ) during eighteen months monitoring account for approximately 1/3rd of the mean annual values. Analysis of heavy metal contents and magnetic parameters for the fraction d  2  = −0.84) is observed between the ratio ARM/χ and Pb content. It suggests that Pb is related to brake/tyre wear emissions, releasing larger particles and higher Pb during slow driving – braking. Bulk χ values of road dusts per city show significant correlation with population size and mean annual NO 2 concentration on a log-normal scale. The results demonstrate the applicability of magnetic measurements of road dusts for estimation of mean NO 2 levels at high spatial density, which is important for pollution modelling and health risk assessment. - Highlights: • temporal variations of road dust magnetic susceptibility comprise 1/3 of the signal. • high negative correlation between Pb content and magnetic ratio ARM/χ is obtained. • brake- and tyre ware emissions are the main pollution sources of the road dusts. • road dust magnetic susceptibility rises parallel with logarithm of population size. • linear correlation is found between mean NO 2 concentrations and susceptibility. - Magnetic susceptibility of road dusts on a national scale increases proportionally to the population size and mean NO 2 concentrations due to the effect of traffic related pollution

  5. Magnetic susceptibility of sodium disilicate glasses containing PuO2

    International Nuclear Information System (INIS)

    Aldred, A.T.

    1979-01-01

    A solubility limit of approx. 6 mol % PuO 2 in sodium disilicate (Na 2 O.2SiO 2 ) glass has been determined. Magnetic susceptibility measurements on these glasses yield approximate Curie-Weiss behavior, in contrast to the temperature-independent susceptibility of crystalline PuO 2 . This result is interpreted to indicate that the local site symmetry around the Pu ion in the sodium disilicate glass is much different than in crystalline PuO 2 . The effective paramagnetic moments determined from the temperature dependence of the susceptibility are found to be consistent with calculated free-ion values based on the most likely 5f electron configurations

  6. Quantitative analysis of magnetic resonance imaging susceptibility artifacts caused by neurosurgical biomaterials. Comparison of 0.5, 1.5, and 3.0 tesla magnetic fields

    International Nuclear Information System (INIS)

    Matsuura, Hideki; Inoue, Takashi; Ogasawara, Kuniaki; Sasaki, Makoto; Konno, Hiromu; Kuzu, Yasutaka; Nishimoto, Hideaki; Ogawa, Akira

    2005-01-01

    Magnetic resonance (MR) imaging is an important diagnostic tool for neurosurgical diseases but susceptibility artifacts caused by biomaterial instrumentation frequently causes difficulty in visualizing postoperative changes. The susceptibility artifacts caused by neurosurgical biomaterials were compared quantitatively by 0.5, 1.5, and 3.0 Tesla MR imaging. MR imaging of uniform size and shape of pieces ceramic (zirconia), pure titanium, titanium alloy, and cobalt-based alloy was performed at 0.5, 1.5, and 3.0 Tesla. A linear region of interest was defined across the center of the biomaterial in the transverse direction, and the susceptibility artifact diameter was calculated. Susceptibility artifacts developed around all biomaterials at all magnetic field strengths. The artifact diameters caused by pure titanium, titanium alloy, and cobalt-based alloy increased in the order of 0.5, 1.5, to 3.0 Tesla magnetic fields. The artifact diameter of ceramic was not influenced by magnetic field strength, and was the smallest of all biomaterials at all magnetic field strengths. The artifacts caused by biomaterials except ceramic increase with the magnetic field strength. Ceramic instrumentation will minimize artifacts in all magnetic fields. (author)

  7. 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

  8. Moessbauer and magnetic susceptibility measurements on M-type hexagonal Ba - ferrite

    International Nuclear Information System (INIS)

    Lipka, J.; Gruskova, A.; Sitek, J.; Miglierini, M.; Groene, R.; Hucl, M.; Toth, I.; Orlicky, O.

    1990-01-01

    Samples of stoichiometric BaFe 12 O 19 and Co, Ti substituted barium ferrite were prepared by chemical wet method. Moessbauer spectroscopy, magnetic susceptibility measurements, X-ray diffraction, infrared spectroscopy were conducted to examine the mechanism of formation. The observed magnetic characteristics and electron scanning microscopy show that single domain coprecipitated powders were formed. (orig.)

  9. Low signal-to-noise FDEM in-phase data: Practical potential for magnetic susceptibility modelling

    Science.gov (United States)

    Delefortrie, Samuël; Hanssens, Daan; De Smedt, Philippe

    2018-05-01

    In this paper, we consider the use of land-based frequency-domain electromagnetics (FDEM) for magnetic susceptibility modelling. FDEM data comprises both out-of-phase and in-phase components, which can be related to the electrical conductivity and magnetic susceptibility of the subsurface. Though applying the FDEM method to obtain information on the subsurface conductivity is well established in various domains (e.g. through the low induction number approximation of subsurface apparent conductivity), the potential for susceptibility mapping is often overlooked. Especially given a subsurface with a low magnetite and maghemite content (e.g. most sedimentary environments), it is generally assumed that susceptibility is negligible. Nonetheless, the heterogeneity of the near surface and the impact of anthropogenic disturbances on the soil can cause sufficient variation in susceptibility for it to be detectable in a repeatable way. Unfortunately, it can be challenging to study the potential for susceptibility mapping due to systematic errors, an often poor low signal-to-noise ratio, and the intricacy of correlating in-phase responses with subsurface susceptibility and conductivity. Alongside use of an accurate forward model - accounting for out-of-phase/in-phase coupling - any attempt at relating the in-phase response with subsurface susceptibility requires overcoming instrument-specific limitations that burden the real-world application of FDEM susceptibility mapping. Firstly, the often erratic and drift-sensitive nature of in-phase responses calls for relative data levelling. In addition, a correction for absolute levelling offsets may be equally necessary: ancillary (subsurface) susceptibility data can be used to assess the importance of absolute in-phase calibration though hereby accurate in-situ data is required. To allow assessing the (importance of) in-phase calibration alongside the potential of FDEM data for susceptibility modelling, we consider an experimental

  10. Study of magnetization switching in coupled magnetic nanostructured systems

    Science.gov (United States)

    Radu, Cosmin

    A study of magnetization dynamics experiments in nanostructured materials using the rf susceptibility tunnel diode oscillator (TDO) method is presented along with a extensive theoretical analysis. An original, computer controlled experimental setup that measures the change in susceptibility with the variation in external magnetic field and sample temperature was constructed. The TDO-based experiment design and construction is explained in detail, showing all the elements of originality. This experimental technique has proven reliable for characterizing samples with uncoupled magnetic structure and various magnetic anisotropies like: CrO2, FeCo/IrMn and Co/SiO2 thin films. The TDO was subsequently used to explore the magnetization switching in coupled magnetic systems, like synthetic antiferromagnet (SAF) structures. Magnetoresistive random access memory (MRAM) is an important example of devices where the use of SAF structure is essential. To support the understanding of the SAF magnetic behavior, its configuration and application are reviewed and more details are provided in an appendix. Current problems in increasing the scalability and decreasing the error rate of MRAM devices are closely connected to the switching properties of the SAF structures. Several theoretical studies that were devoted to the understanding of the concepts of SAF critical curve are reviewed. As one can notice, there was no experimental determination of SAF critical curve, due to the difficulties in characterizing a magnetic coupled structure. Depending of the coupling strength between the two ferromagnetic layers, on the SAF critical curve one distinguishes several new features, inexistent in the case of uncoupled systems. Knowing the configuration of the SAF critical curve is of great importance in order to control its switching characteristics. For the first time a method of experimentally recording the critical curve for SAF is proposed in this work. In order to overcome technological

  11. Magnetic susceptibility of semiconductor melts

    International Nuclear Information System (INIS)

    Kutvitskij, V.A.; Shurygin, P.M.

    1975-01-01

    The temperature dependences chi of various alloys confirm the existence of cluster formations in molten semiconductors, the stability of these formations in melts being considerably affected by the anion nature. The concentrational dependences of the magnetic susceptibility for all the investigated systems exhibit the diamagnetism maxima corresponding to the compound compositions. Heating the melt causes ''smearing'' the maxima, which is related with the cluster structure dissociation. The existence of the maxima concentrational dependence chi corresponding to BiTe and BiSe is found in the isotherms. The non-linear dependence of chi on the composition shows the absence of a single-valued relation between the phase diagram and the chi-diagram for melts

  12. Calculation of the magnetic susceptibilities of transition metal monocarbides, mononitrides and monoxides

    International Nuclear Information System (INIS)

    Eibler, R.; Neckel, A.

    1975-01-01

    Results of Augmented Plane Wave (APW) band structure calculations are used to determine the magnetic susceptibilities of some transition metal monocarbides, mononitrides and monoxides (TiC, TiN, TiO, VC, VN, VO, NbC, NbN) assuming stoichiometric composition. Contributions to the susceptibility arising from the orbital para- and diamagnetism and the spin paramagnetism are determined separately. The orbital susceptibility terms are calculated by means of the model of Kubo and Obata. The calculated susceptibilities are compared with measured values. The approximations in the calculation of the orbital susceptibility terms are discussed especially with regard to the agreement between calculated and measured susceptibilities for the individual compounds. Similar calculations are performed for the susceptibilities of non-stoichiometric VCsub(x)-phase, for which APR-Virtual Crystal Approximation (VCA) band structure calculations are available. (author)

  13. Susceptibility and magnetization of a random Ising model

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, D; Srivastava, V [Roorkee Univ. (India). Dept. of Physics

    1977-08-01

    The susceptibility of a bond disordered Ising model is calculated by configurationally averaging an Ornstein-Zernike type of equation for the two spin correlation function. The equation for the correlation function is derived using a diagrammatic method due to Englert. The averaging is performed using bond CPA. The magnetization is also calculated by averaging in a similar manner a linearised molecular field equation.

  14. Quantitative susceptibility mapping (QSM) as a means to measure brain iron? A post mortem validation study

    Science.gov (United States)

    Langkammer, Christian; Schweser, Ferdinand; Krebs, Nikolaus; Deistung, Andreas; Goessler, Walter; Scheurer, Eva; Sommer, Karsten; Reishofer, Gernot; Yen, Kathrin; Fazekas, Franz; Ropele, Stefan; Reichenbach, Jürgen R.

    2012-01-01

    Quantitative susceptibility mapping (QSM) is a novel technique which allows determining the bulk magnetic susceptibility distribution of tissue in vivo from gradient echo magnetic resonance phase images. It is commonly assumed that paramagnetic iron is the predominant source of susceptibility variations in gray matter as many studies have reported a reasonable correlation of magnetic susceptibility with brain iron concentrations in vivo. Instead of performing direct comparisons, however, all these studies used the putative iron concentrations reported in the hallmark study by Hallgren and Sourander (1958) for their analysis. Consequently, the extent to which QSM can serve to reliably assess brain iron levels is not yet fully clear. To provide such information we investigated the relation between bulk tissue magnetic susceptibility and brain iron concentration in unfixed (in situ) post mortem brains of 13 subjects using MRI and inductively coupled plasma mass spectrometry. A strong linear correlation between chemically determined iron concentration and bulk magnetic susceptibility was found in gray matter structures (r = 0.84, p < 0.001), whereas the correlation coefficient was much lower in white matter (r = 0.27, p < 0.001). The slope of the overall linear correlation was consistent with theoretical considerations of the magnetism of ferritin supporting that most of the iron in the brain is bound to ferritin proteins. In conclusion, iron is the dominant source of magnetic susceptibility in deep gray matter and can be assessed with QSM. In white matter regions the estimation of iron concentrations by QSM is less accurate and more complex because the counteracting contribution from diamagnetic myelinated neuronal fibers confounds the interpretation. PMID:22634862

  15. Quantum renormalizations in anisotropic multisublattice magnets and the modification of magnetic susceptibility under irradiation

    Science.gov (United States)

    Val'kov, V. V.; Shustin, M. S.

    2015-11-01

    The dispersion equation of a strongly anisotropic one-dimensional magnet catena-[FeII(ClO4)2{FeIII(bpca)2}]ClO4 containing alternating high-spin (HS) ( S = 2) and low-spin (LS) ( S = 1/2) iron ions is obtained by the diagram technique for Hubbard operators. The analysis of this equation yields six branches in the excitation spectrum of this magnet. It is important that the crystal field for ions with spin S = 2 is described by the Hamiltonian of single-ion easy-plane anisotropy, whose orientation is changed by 90° when passing from one HS iron ion to another. The U( N) transformation technique in the atomic representation is applied to diagonalize a single-ion Hamiltonian with a large number of levels. It is shown that the modulation of the orientation of easy magnetization planes leads to a model of a ferrimagnet with easy-axis anisotropy and to the formation of energy spectrum with a large gap. For HS iron ions, a decrease in the mean value of the spin projection due to quantum fluctuations is calculated. The analysis of the specific features of the spectrum of elementary excitations allows one to establish a correspondence to a generalized Ising model for which the magnetic susceptibility is calculated in a wide range of temperatures by the transfer-matrix method. The introduction of a statistical ensemble that takes into account the presence of chains of different lengths and the presence of iron ions with different spins allows one to describe the experimentally observed modification of the magnetic susceptibility of the magnet under optical irradiation.

  16. Evaluating the Effects of Magnetic Susceptibility in UXO Discrimination Problems (SERDP SEED Project UX-1285)

    National Research Council Canada - National Science Library

    Pasion, Leonard R; Billings, Stephen D; Oldenburg, Douglas W; Sinex, David; Li, Yaoguo

    2003-01-01

    Using numerical simulations based on magnetic susceptibility properties observed at Kaho'olawe, Hawaii, we have examined the effect of magnetic soil on static magnetic method and time-domain electromagnetic (TEM...

  17. Magnetic susceptibility of free charge carriers in bismuth tellurides (Bi2Te3)

    International Nuclear Information System (INIS)

    Guha Thakurta, S.R.; Dutta, A.K.

    1977-01-01

    Principal magnetic susceptibilities of both p- and n-type Bi 2 Te 3 crystals have been measured over the range of temperature 90 deg K to 650 deg K. The observed susceptibilities are diamagnetic and temperature dependent. This temperature dependence has been attributed to the contribution of the free charge carriers to the susceptibilities. From the observed susceptibilities the carrier-susceptibilities have been separately obtained which are found to be paramagnetic. From the total carrier-susceptibilities, the susceptibilities of the carriers which are thermally liberated in the intrinsic region have been separated. From an analysis of the carrier-susceptibilities the band gap and its temperature coefficient have been found out and these compare favourably with those obtained from electrical measurements. (author)

  18. Variable Temperature Equipment for a Commercial Magnetic Susceptibility Balance

    Science.gov (United States)

    Lotz, Albert

    2008-01-01

    Variable temperature equipment for the magnetic susceptibility balance MSB-MK1 of Sherwood Scientific, Ltd., is described. The sample temperature is controlled with streaming air heated by water in a heat exchanger. Whereas the balance as sold commercially can be used only for room temperature measurements, the setup we designed extends the…

  19. Soil magnetic susceptibility mapping as a pollution and provenance tool: an example from southern New Zealand

    Science.gov (United States)

    Martin, A. P.; Ohneiser, C.; Turnbull, R. E.; Strong, D. T.; Demler, S.

    2018-02-01

    The presence or absence, degree and variation of heavy metal contamination in New Zealand soils is a matter of ongoing debate as it affects soil quality, agriculture and human health. In many instances, however, the soil heavy metal concentration data do not exist to answer these questions and the debate is ongoing. To address this, magnetic susceptibility (a common proxy for heavy metal contamination) values were measured in topsoil (0-30 cm) and subsoil (50-70 cm) at grid sites spaced at 8 km intervals across ca. 20 000 km2 of southern New Zealand. Samples were measured for both mass- and volume-specific magnetic susceptibility, with results being strongly, positively correlated. Three different methods of determining anomalies were applied to the data including the topsoil-subsoil difference method, Tukey boxplot method and geoaccumulation index method, with each method filtering out progressively more anomalies. Additional soil magnetic (hysteresis, isothermal remanence and thermomagnetic) measurements were made on a select subset of samples from anomalous sites. Magnetite is the dominant remanence carrying mineral, and magnetic susceptibility is governed by that minerals concentration in soils, rather than mineral type. All except two anomalous sites have a dominant geogenic source (cf. anthropogenic). By proxy, heavy metal contamination in southern New Zealand soils is minimal, making them relatively pristine. The provenance of the magnetic minerals in the anomalous sites can be traced back to likely sources in outcrops of igneous rocks within the same catchment, terrane or rock type: a distance of Soil provenance is a key step when mapping element or isotopic distribution, vectoring to mineralization or studying soil for agricultural suitability, water quality or environmental regulation. Measuring soil magnetic susceptibility is a useful, quick and inexpensive tool that usefully supplements soil geochemical data.

  20. Spin dynamics of Mn12-acetate in the thermally activated tunneling regime: ac susceptibility and magnetization relaxation

    Science.gov (United States)

    Pohjola, Teemu; Schoeller, Herbert

    2000-12-01

    In this work, we study the spin dynamics of Mn12-acetate molecules in the regime of thermally assisted tunneling. In particular, we describe the system in the presence of a strong transverse magnetic field. Similar to recent experiments, the relaxation time/rate is found to display a series of resonances; their Lorentzian shape is found to stem from the tunneling. The dynamic susceptibility χ(ω) is calculated starting from the microscopic Hamiltonian and the resonant structure manifests itself also in χ(ω). Similar to recent results reported on another molecular magnet, Fe8, we find oscillations of the relaxation rate as a function of the transverse magnetic field when the field is directed along a hard axis of the molecules. This phenomenon is attributed to the interference of the geometrical or Berry phase. We propose susceptibility experiments to be carried out for strong transverse magnetic fields to study these oscillations and for a better resolution of the sharp satellite peaks in the relaxation rates.

  1. Study of the magnetic susceptibilities of some plutonium derivatives; Etude des susceptibilites magnetiques de quelques derives du plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Raphael, G [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1969-06-01

    We present a detailed description of an automatic recording apparatus for magnetic susceptibility measurement of radioactive samples in the temperature range 4 K - 1200 K. We have measured the magnetic susceptibility of various plutonium compounds: - PuO{sub 2}, Pu{sub 2}O{sub 3}, PuO{sub 2-x}, - PuS, Pu{sub 2}S{sub 3}, Pu{sub 3}S{sub 4}, (U{sub x}Pu{sub 1-x})S - PuN - PuC{sub 1-x}(N,O,H,vacancy), Pu{sub 2}C{sub 3}, (U{sub 0.85}Pu{sub 0.15})C. The curves of susceptibilities versus temperature show many magnetic transitions. The interpretation of these results shows the existence of magnetic moments carried by the 5 f electrons and localized on the metallic sites as well as the great influence of the 'crystal field' in all these compounds. (author) [French] Nous decrivons d'une facon detaillee un appareil permettant de mesurer d'une facon continue et automatique des susceptibilites magnetiques sur des echantillons radioactifs dans un domaine de temperature s'etalant de 4 K a 1200 K. Nous avons mesure les susceptibilites magnetiques de certains composes du plutonium tels que: - PuO{sub 2}, Pu{sub 2}O{sub 3}, PuO{sub 2-x} - PuS, Pu{sub 2}S{sub 3}, Pu{sub 3}S{sub 4}, (U{sub x}Pu{sub 1-x})S - PuN - PuC{sub 1-x}(N,O,H,vacancy), Pu{sub 2}C{sub 3}, (U{sub 0.85}Pu{sub 0.15})C. Les courbes de susceptibilite magnetique en fonction de la temperature mettent en evidence de nombreuses transitions magnetiques. L'interpretation de ces resultats a montre l'existence de moments magnetiques portes par les electrons f et localises sur les sites metalliques ainsi que l'influence tres grande du champ cristallin. (auteur)

  2. Study of flow fractionation characteristics of magnetic chromatography utilizing high-temperature superconducting bulk magnet

    Directory of Open Access Journals (Sweden)

    Satoshi Fukui, Yoshihiro Shoji, Jun Ogawa, Tetsuo Oka, Mitsugi Yamaguchi, Takao Sato, Manabu Ooizumi, Hiroshi Imaizumi and Takeshi Ohara

    2009-01-01

    Full Text Available We present numerical simulation of separating magnetic particles with different magnetic susceptibilities by magnetic chromatography using a high-temperature superconducting bulk magnet. The transient transport is numerically simulated for two kinds of particles having different magnetic susceptibilities. The time evolutions were calculated for the particle concentration in the narrow channel of the spiral arrangement placed in the magnetic field. The field is produced by the highly magnetized high-temperature superconducting bulk magnet. The numerical results show the flow velocity difference of the particle transport corresponding to the difference in the magnetic susceptibility, as well as the possible separation of paramagnetic particles of 20 nm diameter.

  3. Study of flow fractionation characteristics of magnetic chromatography utilizing high-temperature superconducting bulk magnet.

    Science.gov (United States)

    Fukui, Satoshi; Shoji, Yoshihiro; Ogawa, Jun; Oka, Tetsuo; Yamaguchi, Mitsugi; Sato, Takao; Ooizumi, Manabu; Imaizumi, Hiroshi; Ohara, Takeshi

    2009-02-01

    We present numerical simulation of separating magnetic particles with different magnetic susceptibilities by magnetic chromatography using a high-temperature superconducting bulk magnet. The transient transport is numerically simulated for two kinds of particles having different magnetic susceptibilities. The time evolutions were calculated for the particle concentration in the narrow channel of the spiral arrangement placed in the magnetic field. The field is produced by the highly magnetized high-temperature superconducting bulk magnet. The numerical results show the flow velocity difference of the particle transport corresponding to the difference in the magnetic susceptibility, as well as the possible separation of paramagnetic particles of 20 nm diameter.

  4. 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.

  5. Mössbauer spectroscopy, magnetization, magnetic susceptibility, and low temperature heat capacity of α-Na2NpO4

    International Nuclear Information System (INIS)

    Smith, Anna L; Hen, Amir; Magnani, Nicola; Colineau, Eric; Griveau, Jean-Christophe; Raison, Philippe E; Caciuffo, Roberto; Konings, Rudy J M; Sanchez, Jean-Pierre; Cheetham, Anthony K

    2016-01-01

    The physical and chemical properties at low temperatures of hexavalent disodium neptunate α-Na 2 NpO 4 are investigated for the first time in this work using Mössbauer spectroscopy, magnetization, magnetic susceptibility, and heat capacity measurements. The Np(VI) valence state is confirmed by the isomer shift value of the Mössbauer spectra, and the local structural environment around the neptunium cation is related to the fitted quadrupole coupling constant and asymmetry parameters. Moreover, magnetic hyperfine splitting is reported below 12.5 K, which could indicate magnetic ordering at this temperature. This interpretation is further substantiated by the existence of a λ-peak at 12.5 K in the heat capacity curve, which is shifted to lower temperatures with the application of a magnetic field, suggesting antiferromagnetic ordering. However, the absence of any anomaly in the magnetization and magnetic susceptibility data shows that the observed transition is more intricate. In addition, the heat capacity measurements suggest the existence of a Schottky-type anomaly above 15 K associated with a low-lying electronic doublet found about 60 cm −1 above the ground state doublet. The possibility of a quadrupolar transition associated with a ground state pseudoquartet is thereafter discussed. The present results finally bring new insights into the complex magnetic and electronic peculiarities of α-Na 2 NpO 4 . (paper)

  6. Magnetic susceptibility as a simple tracer for fluvial sediment source ascription during storm events.

    Science.gov (United States)

    Rowntree, Kate M; van der Waal, Bennie W; Pulley, Simon

    2017-06-01

    ) coincided with the flood peak. Low X lf values indicated that mudstones in the lower catchment soils dominated the sediment load throughout the entire event. Sediment tracing using a single property (X lf) was thus used effectively to study changing sediment sources both between and during a flood event in a catchment with strongly contrasting magnetic signatures in different areas. The results support the use of magnetic susceptibility as a simple and cheap tool to determine sediment provenance that can be used to guide catchment restoration in similar environments. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Magnetic properties of U(Ni1-xCux)2Si2 solid solutions in the vicinity of x = 0.50 studied by neutron diffraction and AC-susceptibility

    International Nuclear Information System (INIS)

    Kuznietz, M.; Andre, G.; Bouree, F.; Pinto, H.; Ettedgui, H.; Melamud, M.

    1993-01-01

    The magnetic properties of two U(Ni 1-x Cu x ) 2 Si 2 solid in the vicinity of x = 0.50 (denoted I and II) have been studied by neutron diffraction and ac-susceptibility. Both materials have ThCr 2 Si 2 -type crystallographic structure. AC-susceptibility shows antiferromagnetic transitions at T N 150±5 K in UNiCuSi 2 (I) and 155±5 K in UNiCuSi 2 (II), followed by several transitions with ferrimagnetic (F) character at lower temperatures. Apart from the transitions to AF-I structure at T N =150K and 152K none of the F transitions is observed by neutron diffraction. Short-range magnetic order, involving several consecutive ferromagnetic planes or ferrimagnetic groups of planes in the AF-I phase, detected by ac-susceptibility and not by neutron diffraction in both materials and therefore significant to x ∼ 0.50, is proposed to explain the unusual susceptibility. (Author)

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

    Digital Repository Service at National Institute of Oceanography (India)

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

    Three sediment cores in a north–south transect (3 degrees N to 13 degrees S) from different sediment types of the Central Indian Ocean Basin (CIOB) are studied to understand the possible relationship between magnetic susceptibility (Chi) and Al, Fe...

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

    Czech Academy of Sciences Publication Activity Database

    Hrouda, F.; Chadima, Martin; Ježek, J.

    2017-01-01

    Roč. 19, EGU General Assembly 2017 (2017) ISSN 1029-7006. [European Geosciences Union General Assembly. 23.04.2017-28.04.2017, Vienna] Institutional support: RVO:67985831 Keywords : anisotropy of magnetic susceptibility * field-dependent susceptibility * pyrrhotite Subject RIV: DE - Earth Magnetism, Geodesy, Geography http://meetingorganizer.copernicus.org/EGU2017/EGU2017-7091.pdf

  10. The ground state magnetic moment and susceptibility of a two electron Gaussian quantum dot

    Science.gov (United States)

    Boda, Aalu; Chatterjee, Ashok

    2018-04-01

    The problem of two interacting electrons moving in a two-dimensional semiconductor quantum dot with Gaussian confinement under the influence of an external magnetic field is studied by using a method of numerical diagonalization of the Hamiltonian matrix with in the effective-mass approximation. The energy spectrum is calculated as a function of the magnetic field. We find the ground state magnetic moment and the magnetic susceptibility show zero temperature diamagnetic peaks due to exchange induced singlet-triplet oscillations. The position and the number of these peaks depend on the size of the quantum dot and also strength of the electro-electron interaction. The theory is applied to a GaAs quantum dot.

  11. Specific heat and magnetic susceptibility vs long range order in V3Ga

    International Nuclear Information System (INIS)

    Junod, A.; Fluekiger, R.; Treyvaud, A.; Muller, J.

    1976-01-01

    A new technique of studying the magnetic susceptibility together with the specific heat and the superconducting transition of typical A15-type compounds in different ordering states enables us to consistently isolate the spin paramagnetism. Satisfactory results are obtained for V 3 Ga and these are compared with data on V 3 Au and Nb 3 (Au-Pt). (author)

  12. Moessbauer, electron paramagnetic resonance and magnetic susceptibility studies of photosensitive nitrile hydratase from Rhodococcus sp. N-771

    International Nuclear Information System (INIS)

    Nagamune, Teruyuki; Honda, Jun; Kobayashi, Yoshio; Sasabe, Hiroyuki; Endo, Isao; Ambe, Fumitoshi; Teratani, Yoshitaka; Hirata, Akira

    1992-01-01

    Moessbauer, magnetic susceptibility and electron paramagnetic resonance (EPR) studies of inactive and photoactivated NHase enzymes were performed to elucidate the electronic change of non-heme two-iron atom center of the enzyme by photoactivation. These spectroscopic investigations revealed that both the two iron atoms of the active NHase could be assigned to low-spin ferric state, and those of the inactive NHase could each be assigned to low-spin ferric and low-spin ferrous ones. From these results, it was concluded that one of the non-heme iron atoms is oxidized in the inactive NHase during photoactivation. (orig.)

  13. Application of magnetic susceptibility as a function of temperature, field and frequency

    Czech Academy of Sciences Publication Activity Database

    Chadima, Martin

    2011-01-01

    Roč. 1, č. 2 (2011), E03-E03 ISSN N. [Latinmag Biennial Meeting /2./. 23.11.2011-26.11.2011, Tandil] Institutional research plan: CEZ:AV0Z30130516 Keywords : palaeomagnetism * magnetic susceptibility * geophysics Subject RIV: DE - Earth Magnetism, Geodesy, Geography http://www. geofisica .unam.mx/LatinmagLetters/LL11-0102P/E/E03-chadima-1.pdf

  14. Characterizing the magnetic susceptibility tensor of lanthanide-containing polymethylated-DOTA complexes

    Energy Technology Data Exchange (ETDEWEB)

    Strickland, Madeleine [National Institutes of Health, Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute (United States); Schwieters, Charles D. [National Institutes of Health, Office of Intramural Research, Center for Information Technology (United States); Göbl, Christoph [Technische Universität München, Department of Chemistry (Germany); Opina, Ana C. L. [National Institutes of Health, Imaging Probe Development Center, National Heart, Lung, and Blood Institute (United States); Strub, Marie-Paule [National Institutes of Health, Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute (United States); Swenson, Rolf E.; Vasalatiy, Olga [National Institutes of Health, Imaging Probe Development Center, National Heart, Lung, and Blood Institute (United States); Tjandra, Nico, E-mail: tjandran@nhlbi.nih.gov [National Institutes of Health, Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute (United States)

    2016-10-15

    Lanthanide complexes based on the DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) cage are commonly used as phase contrast agents in magnetic resonance imaging, but can also be utilized in structural NMR applications due to their ability to induce either paramagnetic relaxation enhancement or a pseudocontact shift (PCS) depending on the choice of the lanthanide. The size and sign of the PCS for any given atom is determined by its coordinates relative to the metal center, and the characteristics of the lanthanide’s magnetic susceptibility tensor. Using a polymethylated DOTA tag (Ln-M8-SPy) conjugated to ubiquitin, we calculated the position of the metal center and characterized the susceptibility tensor for a number of lanthanides (dysprosium, thulium, and ytterbium) under a range of pH and temperature conditions. We found that there was a difference in temperature sensitivity for each of the complexes studied, which depended on the size of the lanthanide ion as well as the isomeric state of the cage. Using {sup 17}O-NMR, we confirmed that the temperature sensitivity of the compounds was enhanced by the presence of an apically bound water molecule. Since amide-containing lanthanide complexes are known to be pH sensitive and can be used as probes of physiological pH, we also investigated the effect of pH on the Ln-M8-SPy susceptibility tensor, but we found that the changes in this pH range (5.0–7.4) were not significant.

  15. Characterizing the magnetic susceptibility tensor of lanthanide-containing polymethylated-DOTA complexes

    International Nuclear Information System (INIS)

    Strickland, Madeleine; Schwieters, Charles D.; Göbl, Christoph; Opina, Ana C. L.; Strub, Marie-Paule; Swenson, Rolf E.; Vasalatiy, Olga; Tjandra, Nico

    2016-01-01

    Lanthanide complexes based on the DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) cage are commonly used as phase contrast agents in magnetic resonance imaging, but can also be utilized in structural NMR applications due to their ability to induce either paramagnetic relaxation enhancement or a pseudocontact shift (PCS) depending on the choice of the lanthanide. The size and sign of the PCS for any given atom is determined by its coordinates relative to the metal center, and the characteristics of the lanthanide’s magnetic susceptibility tensor. Using a polymethylated DOTA tag (Ln-M8-SPy) conjugated to ubiquitin, we calculated the position of the metal center and characterized the susceptibility tensor for a number of lanthanides (dysprosium, thulium, and ytterbium) under a range of pH and temperature conditions. We found that there was a difference in temperature sensitivity for each of the complexes studied, which depended on the size of the lanthanide ion as well as the isomeric state of the cage. Using "1"7O-NMR, we confirmed that the temperature sensitivity of the compounds was enhanced by the presence of an apically bound water molecule. Since amide-containing lanthanide complexes are known to be pH sensitive and can be used as probes of physiological pH, we also investigated the effect of pH on the Ln-M8-SPy susceptibility tensor, but we found that the changes in this pH range (5.0–7.4) were not significant.

  16. Low-temperature magnetic susceptibility of the solid solutions (ErxY1-x)3Al5O12

    International Nuclear Information System (INIS)

    Bagdasarov, Kh.S.; Dodokin, A.P.; Sorokin, A.A.

    1988-01-01

    Measurements of magnetic susceptibility of erbium-yttrium alumogarnets in the 0.04-4.2 K temperature range are carried out. (Er x I 1-x ) 3 Al 5 O 12 monocrystals were grown by the method of vertical directed crystallization. The specimens were produced as 5 cm high cylinders 0.63 cm in diameter; the axis of the cylinders coincided with the (100) direction of the crystals. Magnetic susceptibility was measured by the Harsthorn bridge method at the frequency of 33 Hz. The analysis of measurement results shows that susceptibility of the investigated crystals at T >or approx. 2T N is well described by the Curie-Weiss law. Existence of threshold concentration of the magnetic component testifies to an essential role of exchange interactions in establishment of the magnetic order in Er 3 Al 5 O 12

  17. A kinetic model to explain the grain size and organic matter content dependence of magnetic susceptibility in transitional marine environments: A case study in Ria de Muros (NW Iberia)

    Science.gov (United States)

    Mohamed, Kais J.; Andrade, Alba; Rey, Daniel; Rubio, Belén.; Bernabeu, Ana María.

    2017-06-01

    Magnetic minerals in marine sediments are sensitive indicators of processes such as provenance changes, climatic controls, pollution, and postdepositional geochemical changes. Magnetic susceptibility is the bulk property of the sediments most commonly used to understand the magnetic characteristics of sediments. Before conclusions can be drawn from changes in this parameter, it is important to understand what factors and to what extent control changes in magnetic susceptibility. The magnetic susceptibility of surficial sediments in the Galician Rias Baixas, in NW Spain, has been shown to covary with sediment texture and organic matter content. Downcore, the magnetic properties of these sediments experience drastic changes as a result of strong dissolution caused by early diagenesis. In this paper, we further explore the relationship between these factors and formalize the observed covariations as the result of a simple second-order kinetic model dependent on the content of organic matter in surficial sediments in the Ria de Muros. The reanalysis of previously reported data from the Rias de Vigo and Pontevedra confirmed the validity of this model and suggested further controls such as wave climate and water depth in the rates at which magnetic susceptibility changes are controlled by organic matter content.

  18. Automatic magnetic susceptibility measurements between 4 K and 1200 K

    International Nuclear Information System (INIS)

    Raphael, G.

    1969-01-01

    We give a detailed description of a Faraday magnetic susceptibility balance which operates from 4 K to 1200 K. Some preliminary results on platinum and tantalum illustrate the precision and the sensitivity of the measurements. The apparatus has been designed for measurements on the plutonium compounds which present severe health hazards. (author) [fr

  19. Magnetic susceptibilities and thermal expansion of artificial graphites

    International Nuclear Information System (INIS)

    Cornuault, P.; Herpin, A.; Hering, H.; Seguin, M.; Commissariat a l'Energie Atomique, Saclay

    1960-01-01

    Starting from measurements of the magnetic susceptibility made in the two principal directions of a graphite bar, the distribution function of the normals to the carbon planes in the crystallites has been evaluated. The effect of different variation in the manufacturing process on this crystalline anisotropy has been studied. From this crystalline anisotropy we have calculated the thermal expansion coefficient possessed by a compact mass of crystallites having exactly the same orientational anisotropy as the porous body consideration. The difference between this and the observed expansion coefficient leads to the determination of the expansion of the non-graphitic part of the mass which turns out to have a negative value and is also anisotropic. We have attempted to draw some conclusions from this result. (author) [fr

  20. The influence of interparticle correlations and self-assembly on the dynamic initial magnetic susceptibility spectra of ferrofluids

    International Nuclear Information System (INIS)

    Ivanov, A.O.; Kantorovich, S.S.; Elfimova, E.A.; Zverev, V.S.; Sindt, J.O.; Camp, P.J.

    2017-01-01

    Using computer simulations and a mean-field theoretical approach, we study how the growth in dipolar interparticle correlations manifests itself in the frequency-dependent initial magnetic susceptibility of a ferrofluid. Our recently developed theory gives the correct single-particle Debye-theory results in the low-concentration, non-interacting regime; and it yields the exact leading-order contributions from interparticle correlations. The susceptibility spectra are analysed in terms of the low-frequency behaviours of the real and imaginary parts, and the position of the peak in the imaginary part. By comparing the theoretical predictions to the results from Brownian dynamics simulations, it is possible to identify the conditions where correlations are important, but where self-assembly has not developed. We also provide a qualitative explanation for the behaviour of spectra beyond the mean-field limit. - Highlights: • The interparticle interaction influences the dynamic susceptibility spectra of magnetic fluids. • The imaginary part maximum shifts to lower frequencies due to the dipolar interparticle interaction. • Chain formation should influence the susceptibility spectrum by shifting the absorption peak to lower frequencies.

  1. The influence of interparticle correlations and self-assembly on the dynamic initial magnetic susceptibility spectra of ferrofluids

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, A.O., E-mail: alexey.ivanov@urfu.ru [Institute of Mathematics and Computer Sciences, Ural Federal University, Lenin Avenue 51, 620000 Ekaterinburg (Russian Federation); Kantorovich, S.S. [Institute of Mathematics and Computer Sciences, Ural Federal University, Lenin Avenue 51, 620000 Ekaterinburg (Russian Federation); Faculty of Physics, University of Vienna, Sensengasse 8, 1090 Vienna (Austria); Elfimova, E.A.; Zverev, V.S. [Institute of Mathematics and Computer Sciences, Ural Federal University, Lenin Avenue 51, 620000 Ekaterinburg (Russian Federation); Sindt, J.O. [School of Chemistry, University of Edinburgh, David Brewster Road, Edinburgh EH9 3FJ, Scotland (United Kingdom); Camp, P.J. [Institute of Mathematics and Computer Sciences, Ural Federal University, Lenin Avenue 51, 620000 Ekaterinburg (Russian Federation); School of Chemistry, University of Edinburgh, David Brewster Road, Edinburgh EH9 3FJ, Scotland (United Kingdom)

    2017-06-01

    Using computer simulations and a mean-field theoretical approach, we study how the growth in dipolar interparticle correlations manifests itself in the frequency-dependent initial magnetic susceptibility of a ferrofluid. Our recently developed theory gives the correct single-particle Debye-theory results in the low-concentration, non-interacting regime; and it yields the exact leading-order contributions from interparticle correlations. The susceptibility spectra are analysed in terms of the low-frequency behaviours of the real and imaginary parts, and the position of the peak in the imaginary part. By comparing the theoretical predictions to the results from Brownian dynamics simulations, it is possible to identify the conditions where correlations are important, but where self-assembly has not developed. We also provide a qualitative explanation for the behaviour of spectra beyond the mean-field limit. - Highlights: • The interparticle interaction influences the dynamic susceptibility spectra of magnetic fluids. • The imaginary part maximum shifts to lower frequencies due to the dipolar interparticle interaction. • Chain formation should influence the susceptibility spectrum by shifting the absorption peak to lower frequencies.

  2. 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.

    2016-01-01

    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 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. PMID:27090955

  3. Finite-size effects on the dynamic susceptibility of CoPhOMe single-chain molecular magnets in presence of a static magnetic field

    Science.gov (United States)

    Pini, M. G.; Rettori, A.; Bogani, L.; Lascialfari, A.; Mariani, M.; Caneschi, A.; Sessoli, R.

    2011-09-01

    The static and dynamic properties of the single-chain molecular magnet Co(hfac)2NITPhOMe (CoPhOMe) (hfac = hexafluoroacetylacetonate, NITPhOMe = 4'-methoxy-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) are investigated in the framework of the Ising model with Glauber dynamics, in order to take into account both the effect of an applied magnetic field and a finite size of the chains. For static fields of moderate intensity and short chain lengths, the approximation of a monoexponential decay of the magnetization fluctuations is found to be valid at low temperatures; for strong fields and long chains, a multiexponential decay should rather be assumed. The effect of an oscillating magnetic field, with intensity much smaller than that of the static one, is included in the theory in order to obtain the dynamic susceptibility χ(ω). We find that, for an open chain with N spins, χ(ω) can be written as a weighted sum of N frequency contributions, with a sum rule relating the frequency weights to the static susceptibility of the chain. Very good agreement is found between the theoretical dynamic susceptibility and the ac susceptibility measured in moderate static fields (Hdc≤2 kOe), where the approximation of a single dominating frequency for each segment length turns out to be valid. For static fields in this range, data for the relaxation time, τ versus Hdc, of the magnetization of CoPhOMe at low temperature are also qualitatively reproduced by theory, provided that finite-size effects are included.

  4. Fully automated measurement of anisotropy of magnetic susceptibility using 3D rotator

    Czech Academy of Sciences Publication Activity Database

    Studýnka, J.; Chadima, Martin; Suza, P.

    2014-01-01

    Roč. 629, 26 August (2014), s. 6-13 ISSN 0040-1951 Institutional support: RVO:67985831 Keywords : AMS * Kappabridge * susceptibility tensor Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 2.872, year: 2014

  5. Critical behavior of the magnetic susceptibility of the uniaxial ferromagnet LiHoF4

    DEFF Research Database (Denmark)

    Beauvillain, P.; Renard, J. P.; Laursen, Ib

    1978-01-01

    The magnetic susceptibility of two LiHoF4 single crystals has been measured in the range 1.2-4.2 K. Ferromagnetic order occurs at Tc=1.527 K. Above 2.5 K, the susceptibilities parallel and perpendicular to the fourfold c axis are well interpreted by the molecular-field approximation, taking...

  6. Anomalous behaviour of the magnetic susceptibility of the mixed spin-1 and spin- 1/2 anisotropic Heisenberg model in the Oguchi approximation

    International Nuclear Information System (INIS)

    Bobak, Andrej; Dely, Jan; Pokorny, Vladislav

    2010-01-01

    The effects of both an exchange anisotropy and a single-ion anisotropy on the magnetic susceptibility of the mixed spin-1 and spin- 1/2 Heisenberg model are investigated by the use of an Oguchi approximation. Particular emphasis is given to the simple cubic lattice with coordination number z = 6 for which the magnetic susceptibility is determined numerically. Anomalous behaviour in the thermal variation of the magnetic susceptibility in the low-temperature region is found due to the applied negative single-ion anisotropy field strength. Also, the difference between the behaviours of the magnetic susceptibility of the Heisenberg and Ising models is discussed.

  7. 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.

  8. Magnetic study of iron sorbitol

    Energy Technology Data Exchange (ETDEWEB)

    Lazaro, F.J. E-mail: osoro@posta.unizar.es; Larrea, A.; Abadia, A.R.; Romero, M.S

    2002-09-01

    A magnetic study of iron sorbitol, an iron-containing drug to treat the iron deficiency anemia is presented. Transmission electron microscopy reveals that the system contains nanometric particles with an average diameter of 3 nm whose composition is close to two-line ferrihydrite. The characterisation by magnetisation and AC susceptibility measurements indicates superparamagnetic behaviour with progressive magnetic blocking starting at 8 K. The quantitative analysis of the magnetic results indicates that the system consists of an assembly of very small magnetic moments, presumably originated by spin uncompensation of the antiferromagnetic nanoparticles, with Arrhenius type magnetic dynamics.

  9. Magnetic susceptibility of scandium-hydrogen and lutetium-hydrogen solid-solution alloys from 2 to 3000K

    International Nuclear Information System (INIS)

    Stierman, R.J.

    1982-12-01

    Results for pure Sc show that the maximum and minimum in the susceptibility discovered earlier are enhanced as the impurity level of iron in scandium decreases. The Stoner enhancement factor, calculated from low-temperature heat capacity data, susceptibility data, and band-structure calculations show Sc to be a strongly enhanced paramagnet. Below 2 0 K, the magnetic anisotropy between the hard and easy directions of scandium decreases linearly with decreasing temperature, tending toward zero at 0 K. The large increase in the susceptibility of Sc at lower temperatures indicates magnetic ordering. Pure Lu and Lu-H alloys showed an anisotropy in susceptibility vs orientation; thus the samples were not random polycrystalline samples. Pure Lu shows the shallow maximum and minimum, but the increase in susceptibility at low temperatures is larger than previously observed. The susceptibility-composition dependence of the Lu-H alloys also did not match other data. The susceptibility-composition dependence does not match the composition dependence of the electronic specific heat constant below 150 K, showing the electronic specific heat is being affected by terms other than phonon-electron and pure electron-electron interactions

  10. Magnetic susceptibility measurements of σ plutonium alloys. Contribution to the study of the 5f electrons localization in the plutonium

    International Nuclear Information System (INIS)

    Meot-Reymond, S.

    1996-01-01

    Physical properties of actinide metals are essentially ruled by the 5f electrons localization. From a theoretically point of view, this localization is more important in the δ-phase than in the α-one. To compare their magnetic behaviour, low temperature magnetic susceptibility measurements have been performed and previous-resistivity data have been analysed. Experimental results and theoretical data can be conciliate by the existence of a Kondo effect in the δ-Pu phase. (author)

  11. A.c. susceptibility measurements in the presence of d.c. magnetic fields for Nd-Ba-Cu-O superconductors

    International Nuclear Information System (INIS)

    Watahiki, M.; Murakami, M.; Yoo, S.I.

    1997-01-01

    We report the temperature and magnetic field dependence of the complex a.c. susceptibility with bias d.c. magnetic fields for melt-processed Nd-Ba-Cu-O superconductor. The onset temperature (T onset ) of the real part of a.c. susceptibility shifted to a lower temperature with increasing d.c. magnetic field. The superconducting transition temperature (T c ) determined by d.c. magnetization measurements did not shift appreciably to a lower-temperature region with increasing d.c. magnetic field. The distinction between T onset and T c indicates that the a.c. susceptibility measurements detect the energy dissipation generated by the motion of flux lines. We have also measured flux profiles and found that there was no appreciable change in flux penetration below and above the peak field, which suggests that the peak effect in Nd-Ba-Cu-O is not due to the phase transition in the flux line lattice. (author)

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

    Czech Academy of Sciences Publication Activity Database

    Zablotskyy, Vitaliy A.; Pérez-Landazábal, J.I.; Recarte, V.; Gómez-Polo, C.

    2010-01-01

    Roč. 22, č. 31 (2010), 316004/1-316004/7 ISSN 0953-8984 Institutional research plan: CEZ:AV0Z10100520 Keywords : shape memory alloys * magnetic susceptibility * martensitic transition * magnetic domains Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.332, year: 2010

  13. Surveying the anthropogenic impact of the Moldau river sediments and nearby soils using magnetic susceptibility

    Czech Academy of Sciences Publication Activity Database

    Knab, M.; Hoffmann, V.; Petrovský, Eduard; Kapička, Aleš; Jordanova, N.; Appel, E.

    2006-01-01

    Roč. 49, č. 4 (2006), s. 527-535 ISSN 0943-0105 Institutional research plan: CEZ:AV0Z3012916 Keywords : Moldau river sediments * magnetic susceptibility * anthropogenic impact Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.610, year: 2006

  14. Kohn anomalies in momentum dependence of magnetic susceptibility of some three-dimensional systems

    Science.gov (United States)

    Stepanenko, A. A.; Volkova, D. O.; Igoshev, P. A.; Katanin, A. A.

    2017-11-01

    We study a question of the presence of Kohn points, yielding at low temperatures nonanalytic momentum dependence of magnetic susceptibility near its maximum, in electronic spectra of some threedimensional systems. In particular, we consider a one-band model on face-centered cubic lattice with hopping between the nearest and next-nearest neighbors, which models some aspects of the dispersion of ZrZn2, and the two-band model on body-centered cubic lattice, modeling the dispersion of chromium. For the former model, it is shown that Kohn points yielding maxima of susceptibility exist in a certain (sufficiently wide) region of electronic concentrations; the dependence of the wave vectors, corresponding to the maxima, on the chemical potential is investigated. For the two-band model, we show the existence of the lines of Kohn points, yielding maximum susceptibility, whose position agrees with the results of band structure calculations and experimental data on the wave vector of antiferromagnetism of chromium.

  15. Effects of magnetic and nonmagnetic impurities on the spin susceptibility of a noncentrosymmetrical superconductor: Application to CePt3Si

    Science.gov (United States)

    Yavari, H.; Mokhtari, M.; Tamaddonpour, M.

    2013-10-01

    The combined effect of nonmagnetic and magnetic impurities on the spin susceptibility of a noncentrosymmetrical superconductor by considering a Cooper pairing model with a two-component order parameter composed of spin-singlet and spin-triplet pairing components is investigated. For clean superconductor CePt3Si, the low-temperature dependence (T →0) of spin susceptibility is linear which suggests that the gap function has line nodes, consistent with our gap model. We will show that in the presence of magnetic impurities the susceptibility does not vanish even in the absence of spin orbit coupling and in the region where the energy gap still is finite, and in the low concentration of magnetic impurities the spin susceptibility at zero temperature is proportional to impurity concentration.

  16. 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

  17. Magnetic susceptibility and zone structure of solid solutions in ZrC-NbN and Zrsub(0.5)Nbsub(0.5)Csub(x)Nsub(1-x) systems

    International Nuclear Information System (INIS)

    Gusev, A.I.; Dubrovskaya, L.B.; Shvejkin, G.P.

    1975-01-01

    Face-centered cubic solid solutions in the systems ZrC-NbN and Zrsub(0.5)Nbsub(0.5)Csub(x)Nsub(1-x) arranged to the mutual substitution type have been synthesized. The concentration and temperature dependences of the magnetic susceptibility have been studied. The extremal nature of the concentrational dependences of the magnetic susceptibility and the magnetic susceptibility temperature coefficient in the system ZrC-NbN is determined. The possibility is shown of considering the stoichiometric carbides and nitrides of the transition metals of the same period within the framework of the model of a single zone structure

  18. Feasibility study of determining axial stress in ferromagnetic bars using reciprocal amplitude of initial differential susceptibility obtained from static magnetization by permanent magnets

    Science.gov (United States)

    Deng, Dongge; Wu, Xinjun

    2018-03-01

    An electromagnetic method for determining axial stress in ferromagnetic bars is proposed. In this method, the tested bar is under the static magnetization provided by permanent magnets. The tested bar do not have to be magnetized up to the technical saturation because reciprocal amplitude of initial differential susceptibility (RAIDS) is adopted as the feature parameter. RAIDS is calculated from the radial magnetic flux density Br Lo = 0.5 at the Lift-off Lo = 0.5 mm, radial magnetic flux density Br Lo = 1 at the Lift-off Lo = 1 mm and axial magnetic flux density Bz Lo = 1 at the Lift-off Lo = 1 mm from the surface of the tested bar. Firstly, the theoretical derivation of RAIDS is carried out according to Gauss' law for magnetism, Ampere's Law and the Rayleigh relation in Rayleigh region. Secondly, the experimental system is set up for a 2-meter length and 20 mm diameter steel bar. Thirdly, an experiment is carried out on the steel bar to analyze the relationship between the obtained RAIDS and the axial stress. Experimental results show that the obtained RAIDS decreases almost linearly with the increment of the axial stress inside the steel bar in the initial elastic region. The proposed method has the potential to determine tensile axial stress in the slender cylindrical ferromagnetic bar.

  19. On the relevance of the ac magnetic susceptibility on the study of superconductors

    International Nuclear Information System (INIS)

    Khoder, A.F.; Couach, M.; Barbara, B.

    1988-01-01

    It is shown that the ac susceptibility method allows to study in details the bulk superconductivity of as well homogeneous and inhomogeneous materials, such as high-T c superconductors. Shielding and Meissner effects at T c can be distinguished by a careful analysis of x' and x'' components of the susceptibility

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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.

  1. Neutron diffraction, specific heat and magnetic susceptibility of Ni3(PO4)2

    International Nuclear Information System (INIS)

    Escobal, J.; Pizarro, J.L.; Mesa, J.L.; Rojo, J.M.; Bazan, B.; Arriortua, M.I.; Rojo, T.

    2005-01-01

    The Ni 3 (PO 4 ) 2 phosphate was synthesized by the ceramic method in air atmosphere. The crystal structure consists of a three-dimensional skeleton constructed from Ni 3 O 14 edge-sharing octahedra, which are interconnected by (PO 4 ) 3- oxoanions with tetrahedral geometry. The magnetic behavior was studied on powdered sample by using susceptibility, specific heat and neutron diffraction data. The nickel(II) orthophosphate exhibits a three-dimensional magnetic ordering at approximately 17.1 K. However, its complex crystal structure hampers any parametrization of the J-exchange parameter. The specific heat measurements of Ni 3 (PO 4 ) 2 exhibit a three-dimensional magnetic ordering (λ-type) peak at 17.1 K. Measurements above T N suggest the presence of a small short-range order in this phase. The total magnetic entropy was found to be 28.1 KJ/mol at 50 K. The magnetic structure of the nickel(II) phosphate exhibits ferromagnetic interactions inside the Ni 3 O 14 trimers which are antiferromagnetically coupled between them, giving rise to a purely antiferromagnetic structure

  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. Quantification of susceptibility artifacts in 0.5, 1.5 and 3.0 tesla magnetic resonance imaging produced from various biomaterials

    International Nuclear Information System (INIS)

    Matsuura, Hideki

    2002-01-01

    Several studies have examined various biomaterials to minimize susceptibility artifacts using low magnetic fields such as 0.5 Tesla or 1.5 Tesla, but no work has been done with high magnetic field. The purpose of the present study was to quantify the susceptibility artifacts produced from various biomaterials for neurosurgical implants in 0.5, 1.5 and 3.0 Tesla MR scanner. We performed MR imaging of six kinds of ceramics, two kinds of Co-based alloys with different combination, pure titanium, titanium alloy and stainless steel. Images were transferred to computer and analyzed. On all biomaterials, susceptibility artifacts developed parallel to the direction of the main magnetic field at both ends. Ceramics had considerably smaller artifact diameter compared with other biomaterials. Among ceramics, the artifact diameter of zirconia was the smallest. There were few differences between the artifact diameter of pure titanium and that of titanium alloy. Ceramics are promising biomaterials for minimum artifacts in higher field MR system. Although it is necessary to carry out degradation tests or retention force evaluation of the ceramics, we considered the ceramics are the most suitable biomaterials for the artifacts in MR imaging. (author)

  4. High magnetic susceptibility granodiorite as a source of surface magnetic anomalies in the King George Island, Antarctica

    Science.gov (United States)

    Kon, S.; Nakamura, N.; Funaki, M.; Sakanaka, S.

    2012-12-01

    Change in plate motion produces convergence of the two oceanic lithospheres and the formation of volcanic island arcs above the subducted older and thicker plate. The association of calc-alkaline diorites to tonalites and granodiorites (ACG) is typical plutonic rocks of the volcanic arcs. In the many island arcs that surround the Pacific Ocean, ACG generally forms shallow level plutons and is closely associated with volcanic rocks. The Japan Arc setting had occurred the emplacement of the highly magnetic granitoid along the fore-arc basin before back-arc spreading at middle Miocene, showing a linear positive magnetic anomaly. Similar magnetic anomalies have also been exhibited along the Circum-Pacific Belt. Along East Antarctica, it is well known that the South Shetland Islands have been formed by back-arc spreading related to the subduction along the South Shetland trench during the late Cretaceous and middle Miocene. Moreover, geology in the South Shetland Islands consists of lava flows with subordinate pyroclastic deposits, intrusive dykes-sills, granitic plutons, displaying a typical subduction-related calc-alkaline volcanic association. However, there is little report on the presence of fore-arc granitoid. Here we report the distribution and structure of the granitic plutons around Marian Cove in the King George Island, South Shetland, East Antarctica by surface geological survey and magnetic anisotropic studies. Then we compare the distribution of granitic plutons with surface magnetic anomalies through our ship-borne and foot-borne magnetic surveys. The granitic plutons are distributed only shallow around the Marian cove in the King George Island, and the plutons had been intruded in the Sejong formation with pyroclastic deposits and basaltic/rhyoritic lavas, suggesting the post back-arc spreading. We sampled 8 plutons, 12 basaltic lavas and 6 andestic dykes, all located within four kilometer radius from the Korean Antarctic research station (King Sejong

  5. Geochemical normalization of magnetic susceptibility for investigation of floodplain sediments

    Czech Academy of Sciences Publication Activity Database

    Faměra, Martin; Matys Grygar, Tomáš; Elznicová, J.; Grison, Hana

    2018-01-01

    Roč. 77, č. 5 (2018), č. článku 189. ISSN 1866-6280 R&D Projects: GA ČR(CZ) GA15-00340S Institutional support: RVO:61388980 ; RVO:67985530 Keywords : Background functions * Geochemical normalization * Mass-specific magnetic susceptibility * Post-depositional processes * Provenance Subject RIV: DD - Geochemistry OBOR OECD: Environmental sciences (social aspects to be 5.7); Geology (GFU-E) Impact factor: 1.569, year: 2016

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

    Energy Technology Data Exchange (ETDEWEB)

    Buot, Felix A., E-mail: fbuot@gmu.edu [Computational Materials Science Center, George Mason University, Fairfax, VA 22030 (United States); TCSE Center, Spintronics Group, Physics Department, University of San Carlos, Talamban, Cebu 6000 (Philippines); C& LB Research Institute, Carmen, Cebu 6005 (Philippines); Otadoy, Roland E.S.; Rivero, Karla B. [TCSE Center, Spintronics Group, Physics Department, University of San Carlos, Talamban, Cebu 6000 (Philippines)

    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.

  7. 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 (ptesting 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-middle Holocene. We hypothesize that prolonged drought during the early and middle Holocene reduced flood frequency and magnitude and the likelihood of soil burial, resulting in longer soil forming intervals and higher Xlf values. Although precipitation influences the Xlf signature, the results from this study suggest that the magnetic susceptibility values of well-drained buried floodplain soils along the Delaware River Valley are partly a function of time.

  8. Magnetic susceptibility of LaxCe1-xF3 single crystals

    International Nuclear Information System (INIS)

    Paradowski, M.L.; Pacyna, A.W.; Bombik, A.; Korczak, W.; Korczak, S.Z.

    2000-01-01

    The magnetic susceptibility of La x Ce 1-x F 3 single crystals, for 0 eff and paramagnetic Curie temperature θ p have been obtained, using the Curie-Weiss law in the temperature range 100-300 K. The interconfiguration excited energy E ex , the spin-fluctuation temperature T sf , and the g-values, corresponding to three Kramers doublets in the 2 F 5/2 ground multiplet of Ce 3+ ion in La x Ce 1-x F 3 have been determined, using quantum theory of paramagnetic susceptibility. The mixed-valent and crystal field effects influence significantly the g-values. The effect of the dilution of the paramagnetic Ce 3+ ions with diamagnetic La 3+ ions is also discussed

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

    Directory of Open Access Journals (Sweden)

    Shimakura Hironori

    2017-01-01

    Full Text Available 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.

  10. Magnetic excitation and local magnetic susceptibility of the excitonic insulator Ta2NiSe5 investigated by 77Se NMR

    Science.gov (United States)

    Li, Shang; Kawai, Shunsuke; Kobayashi, Yoshiaki; Itoh, Masayuki

    2018-04-01

    77Se NMR measurements were made on polycrystalline and single-crystalline samples to elucidate local magnetic susceptibility and magnetic excitation of Ta2NiSe5 , which is proposed to undergo an exciton condensation accompanied by a structural transition at Tc=328 K . We determine the 77Se Knight shift tensors for the three Se sites and analyze their anisotropy based on the site symmetry. The temperature dependence of the Knight shift is discussed on the basis of spin and orbital susceptibilities calculated for two-chain and two-dimensional three-band models. The large fraction of the Se 4 p orbital polarization due to the mixing between Ni 3 d and Se 4 p orbitals is estimated from the analysis of the transferred hyperfine coupling constant. Also the nuclear spin-lattice relaxation rate 1 /T1 is found not to show a coherent peak just below Tc and to obey the thermally activated temperature dependence with a spin gap energy of 1770 ±40 K . This behavior of 1 /T1 monitors the exciton condensation as proposed by the theoretical study of 1 /T1 based on the three-chain Hubbard model for the excitonic insulator.

  11. Susceptibility Tensor Imaging (STI) of the Brain

    Science.gov (United States)

    Li, Wei; Liu, Chunlei; Duong, Timothy Q.; van Zijl, Peter C.M.; Li, Xu

    2016-01-01

    Susceptibility tensor imaging (STI) is a recently developed MRI technique that allows quantitative determination of orientation-independent magnetic susceptibility parameters from the dependence of gradient echo signal phase on the orientation of biological tissues with respect to the main magnetic field. By modeling the magnetic susceptibility of each voxel as a symmetric rank-2 tensor, individual magnetic susceptibility tensor elements as well as the mean magnetic susceptibility (MMS) and magnetic susceptibility anisotropy (MSA) can be determined for brain tissues that would still show orientation dependence after conventional scalar-based quantitative susceptibility mapping (QSM) to remove such dependence. Similar to diffusion tensor imaging (DTI), STI allows mapping of brain white matter fiber orientations and reconstruction of 3D white matter pathways using the principal eigenvectors of the susceptibility tensor. In contrast to diffusion anisotropy, the main determinant factor of susceptibility anisotropy in brain white matter is myelin. Another unique feature of susceptibility anisotropy of white matter is its sensitivity to gadolinium-based contrast agents. Mechanistically, MRI-observed susceptibility anisotropy is mainly attributed to the highly ordered lipid molecules in myelin sheath. STI provides a consistent interpretation of the dependence of phase and susceptibility on orientation at multiple scales. This article reviews the key experimental findings and physical theories that led to the development of STI, its practical implementations, and its applications for brain research. PMID:27120169

  12. Magnetic properties of natural pyrrhotite Part I : Behaviour of initial susceptibility and saturation-magnetization-related rock-magnetic parameters in a grain-size dependent framework

    NARCIS (Netherlands)

    Dekkers, M.J.

    1988-01-01

    The grain-size dependence of the initial susceptibility, saturation magnetization, saturation remanence , coercive force, remanent coercive force and remanent acquisition coercive force, is reported for four natural pyrrhotites in a grain-size range from 250 µm down to <5 µm.

  13. 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.

  14. Magnetic viscosity, susceptibility and fluctuation fields in sintered NdFeB

    International Nuclear Information System (INIS)

    Tomka, G.J.; Bissell, P.R.; O'Grady, K.; Chantrell, R.W.

    1990-01-01

    Magnetic viscosity and irreversible susceptibility of a sample of anisotropic sintered NdFeB have been measured using a vibrating sample magnetometer. The fluctuation field as a function of local field is found to decrease with increasing demagnetizing field with a dip at the coercivity. This behavior is compared with an existing computer model based on a non-interacting system of fine, uniaxial, randomly oriented particles

  15. IDENTIFYING ANTHROPOGENIC METALLIC POLLUTANTS USING FREQUENCY DEPENDENT MAGNETIC SUSCEPTIBILITY MEASUREMENTS IN ABUJA METROPOLIS

    Directory of Open Access Journals (Sweden)

    Jatto S. Solomon

    2017-07-01

    Full Text Available Soil formed from lithological and weathering processes of parent rocks generally exhibit paramagnetic properties due to some minerals contained in the rocks and thus have significant value of magnetic susceptibility. This susceptibility arising from the influence of the parent rocks tend to mask anthropogenic grains pollutants released into the environment by human activities. Hence, it becomes difficult to identify the effect of the lithological and anthropogenic magnetic susceptibility in complex soil found in urban areas. The superparamagnetic effect of lithological soil, a single state domain and multi-domain state of anthropogenic grains can easily be investigated by frequency dependent measurements where readings between 0-2.0% indicates the absence of lithological influence, 2.0-8.0% indicates multi-domain grains or mixture of both single stage and multi-domian grains and 8.0-12% indicates the superparamagntic (SP grain from lithological origin. In this work frequency dependent measurements were carried out along 5 selected road networks within the 5 districts of Abuja phase 1. Measurements were also carried out in 379 random points at the surface and depth of 40.0cm to investigate the distribution of anthropogenic grains in Abuja metropolis using the Bartington susceptibility meter. Frequency dependent measurements along the selected road networks indicate0-3.0% immediately after the roads pavement to a distance of about 3.0m from the road, indicating that the magnetic susceptibility arise mostly form anthropogenic influence rather than lithological processes. At the distance of 3.0-8.0m, frequency dependent values of about 3.0-8.0% were recorded, indicating mixture of both superparamagnetic and multi-domain grains. Beyond the distance of 8.0m, the frequency dependent values are mostly above 8.0.0%, indicating virtually all SP grains. The spatial distribution frequency dependent surface map shows the presence of anthropogenic grains in

  16. Susceptibility tensor imaging (STI) of the brain.

    Science.gov (United States)

    Li, Wei; Liu, Chunlei; Duong, Timothy Q; van Zijl, Peter C M; Li, Xu

    2017-04-01

    Susceptibility tensor imaging (STI) is a recently developed MRI technique that allows quantitative determination of orientation-independent magnetic susceptibility parameters from the dependence of gradient echo signal phase on the orientation of biological tissues with respect to the main magnetic field. By modeling the magnetic susceptibility of each voxel as a symmetric rank-2 tensor, individual magnetic susceptibility tensor elements as well as the mean magnetic susceptibility and magnetic susceptibility anisotropy can be determined for brain tissues that would still show orientation dependence after conventional scalar-based quantitative susceptibility mapping to remove such dependence. Similar to diffusion tensor imaging, STI allows mapping of brain white matter fiber orientations and reconstruction of 3D white matter pathways using the principal eigenvectors of the susceptibility tensor. In contrast to diffusion anisotropy, the main determinant factor of the susceptibility anisotropy in brain white matter is myelin. Another unique feature of the susceptibility anisotropy of white matter is its sensitivity to gadolinium-based contrast agents. Mechanistically, MRI-observed susceptibility anisotropy is mainly attributed to the highly ordered lipid molecules in the myelin sheath. STI provides a consistent interpretation of the dependence of phase and susceptibility on orientation at multiple scales. This article reviews the key experimental findings and physical theories that led to the development of STI, its practical implementations, and its applications for brain research. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  17. Influence of deuterium on the magnetic susceptibility and thermal expansion of the mixed valence compound CePd3

    International Nuclear Information System (INIS)

    Weinzierl, P.; Blaschko, O.; Fratzl, P.; Krexner, G.; Ernst, G.; Hilscher, G.

    1984-01-01

    The possibility of studying mixed valent rare earth compounds by addition of interstitially solved hydrogen is discussed. First measurements of the thermal expansion and of the magnetic susceptibility of 4 K in intermediate valent CePd 3 Dsub(0.05) are presented. (orig.) [de

  18. Changes of deep gray matter magnetic susceptibility over 2years in multiple sclerosis and healthy control brain

    Directory of Open Access Journals (Sweden)

    Jesper Hagemeier

    Full Text Available In multiple sclerosis, pathological changes of both tissue iron and myelin occur, yet these factors have not been characterized in a longitudinal fashion using the novel iron- and myelin-sensitive quantitative susceptibility mapping (QSM MRI technique. We investigated disease-relevant tissue changes associated with myelin loss and iron accumulation in multiple sclerosis deep gray matter (DGM over two years. One-hundred twenty (120 multiple sclerosis patients and 40 age- and sex-matched healthy controls were included in this prospective study. Written informed consent and local IRB approval were obtained from all participants. Clinical testing and QSM were performed both at baseline and at follow-up. Brain magnetic susceptibility was measured in major DGM structures. Temporal (baseline vs. follow-up and cross-sectional (multiple sclerosis vs. controls differences were studied using mixed factorial ANOVA analysis and appropriate t-tests. At either time-point, multiple sclerosis patients had significantly higher susceptibility in the caudate and globus pallidus and lower susceptibility in the thalamus. Over two years, susceptibility increased significantly in the caudate of both controls and multiple sclerosis patients. Inverse thalamic findings among MS patients suggest a multi-phase pathology explained by simultaneous myelin loss and/or iron accumulation followed by iron depletion and/or calcium deposition at later stages. Keywords: Quantitative susceptibility mapping, QSM, Iron, Multiple sclerosis, Longitudinal study

  19. Characterization of magnetic core-shell nanoparticles by fluxgate magnetorelaxometry, ac susceptibility, transmission electron microscopy and photon correlation spectroscopy-A comparative study

    International Nuclear Information System (INIS)

    Ludwig, Frank; Heim, Erik; Schilling, Meinhard

    2009-01-01

    We have compared the structure parameters of magnetic core-shell nanoparticles determined from fluxgate magnetorelaxometry measurements applying the moment superposition model with the results from other methods. For the characterization of the magnetic cores, the nanoparticles are immobilized by freeze-drying. The core size distribution estimated for superparamagnetic Fe 3 O 4 magnetic nanoparticles (MNPs) with polyacrylic acid shell agrees well with that from transmission electron microscopy measurements. The distribution of hydrodynamic diameters of nanoparticle suspensions estimated from magnetorelaxometry measurements is in good agreement with that obtained from ac susceptibility and photon correlation spectroscopy measurements. Advantages of magnetorelaxometry compared to the other two integral techniques are that it is fast and the signal is less dominated by larger particles.

  20. Comparison of Magnetic Susceptibility Tensor and Diffusion Tensor of the Brain.

    Science.gov (United States)

    Li, Wei; Liu, Chunlei

    2013-10-01

    Susceptibility tensor imaging (STI) provides a novel approach for noninvasive assessment of the white matter pathways of the brain. Using mouse brain ex vivo , we compared STI with diffusion tensor imaging (DTI), in terms of tensor values, principal tensor values, anisotropy values, and tensor orientations. Despite the completely different biophysical underpinnings, magnetic susceptibility tensors and diffusion tensors show many similarities in the tensor and principal tensor images, for example, the tensors perpendicular to the fiber direction have the highest gray-white matter contrast, and the largest principal tensor is along the fiber direction. Comparison to DTI fractional anisotropy, the susceptibility anisotropy provides much higher sensitivity to the chemical composition of the white matter, especially myelin. The high sensitivity can be further enhanced with the perfusion of ProHance, a gadolinium-based contrast agent. Regarding the tensor orientations, the direction of the largest principal susceptibility tensor agrees with that of diffusion tensors in major white matter fiber bundles. The STI fiber tractography can reconstruct the fiber pathways for the whole corpus callosum and for white matter fiber bundles that are in close contact but in different orientations. There are some differences between susceptibility and diffusion tensor orientations, which are likely due to the limitations in the current STI reconstruction. With the development of more accurate reconstruction methods, STI holds the promise for probing the white matter micro-architectures with more anatomical details and higher chemical sensitivity.

  1. Magnetic study of turbidites

    Science.gov (United States)

    Tanty, Cyrielle; Valet, Jean Pierre; Carlut, Julie

    2015-04-01

    Turbidites induce sedimentary reworking and re-deposition caused by tsunami, earthquake, volcanic processes, and other catastrophic events. They result from rapid depositional processes and are thus considered not being pertinent for comparison with pelagic sediments. Turbidites are evidently ruled out from paleomagnetic records dealing with time-series. Consequently, no attention has ever been paid to the magnetization of turbidites which is fully justified if the high level of turbulence governing the depositional processes influences the acquisition of magnetization. In certain conditions like channeled turbidity currents, levees of sediment are generated and then associated with relatively calm although very fast redeposition processes. Such conditions will thus govern the subsequent acquisition of magnetization through mechanical lock-in of the magnetic grains. This situation is actually quite similar to what happens during the experiences of artificial redeposition that are conducted in laboratory. Therefore, combining laboratory experiments and studies of natural turbidites could reveal important information on the processes involved in the acquisition of magnetization, especially if the comparison with the overlying hemipelagic sediments does not show any striking difference. We will present the results of magnetic measurements performed on four different and relatively recent turbidites. We selected different origins associated either with spillover of channeled turbidity currents or with co-seismic faulting. Each event is characterized by a different thickness (ten to few tens of cm), lithology and mean granulometry (few tens of μm to hundreds of μm). We have carried out measurements of magnetic susceptibility, magnetic remanence, anisotropy of magnetic susceptibility (AMS) and we also scrutinize the evolution of various rock magnetic parameters (ARM, IRM, S ratio, magnetic grain sizes, hysteresis parameters…). The magnetic characteristics of the

  2. Mechanism of formation of volcanic bombs: insights from a pilot study of anisotropy of magnetic susceptibility and preliminary assessment of analytical models

    Science.gov (United States)

    Cañón-Tapia, Edgardo

    2017-07-01

    Volcanic bombs and achneliths are a special type of pyroclastic fragments formed by mildly explosive volcanic eruptions. Models explaining the general shapes of those particles can be divided in two broad categories. The most popular envisages the acquisition of shapes of volcanic bombs as the result of the rush of air acting on a fluid clot during flight, and it includes many variants. The less commonly quoted model envisages their shapes as the result of forces acting at the moment of ejection of liquid from the magma pool in the conduit, experiencing an almost negligible modification through its travel through air. Quantitative evidence supporting either of those two models is limited. In this work, I explore the extent to which the anisotropy of magnetic susceptibility (AMS) might be useful in the study of mechanisms of formation of volcanic bombs by comparing measurements made on two spindle and two bread-crusted bombs. The results of this pilot study reveal that the degree of anisotropy of spindle bombs is larger, and their principal susceptibility axes are better clustered than on bread-crusted bombs. Also, the orientation of the principal susceptibility axes is consistent with two specific models (one of the in-flight variants and the general ejection model). Consequently, the reported AMS measurements, albeit limited in number, indicate that it is reasonable to focus attention on only two specific models to explain the acquisition of the shapes of volcanic bombs. Based on a parallel theoretical assessment of analytical models, a third alternative is outlined, envisaging volcanic bomb formation as a two-stage process that involves the bursting of large ( m) gas bubbles on the surface of a magma pond. The new model advanced here is also consistent with the reported AMS results, and constitutes a working hypothesis that should be tested by future studies richer in data. Fortunately, since this work also establishes that AMS can be used to determine magnetic

  3. Studies of. gamma. -ray irradiation effects on tris(. beta. -diketonato)iron(III) and cobalt(III) coordination compounds by means of Moessbauer spectroscopy and magnetic susceptibility measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Y.; Endo, K.; Sano, H. (Tokyo Metropolitan Univ. (Japan). Faculty of Science)

    1981-06-01

    Both absorption Moessbauer spectroscopy and magnetic susceptibility measurements on tris(..beta..-diketonato)iron(III) and cobalt(III) compounds indicate that ligands which have phenyl group as a substituent are more stable to ..gamma..-ray radiolysis, in accordance with previous results of emission Moessbauer spectroscopic studies of /sup 57/Co-labelled tris (..beta..-diketonato)cobalt(III) compounds.

  4. Quantitative Susceptibility Mapping: Contrast Mechanisms and Clinical Applications

    Science.gov (United States)

    Liu, Chunlei; Wei, Hongjiang; Gong, Nan-Jie; Cronin, Matthew; Dibb, Russel; Decker, Kyle

    2016-01-01

    Quantitative susceptibility mapping (QSM) is a recently developed MRI technique for quantifying the spatial distribution of magnetic susceptibility within biological tissues. It first uses the frequency shift in the MRI signal to map the magnetic field profile within the tissue. The resulting field map is then used to determine the spatial distribution of the underlying magnetic susceptibility by solving an inverse problem. The solution is achieved by deconvolving the field map with a dipole field, under the assumption that the magnetic field is a result of the superposition of the dipole fields generated by all voxels and that each voxel has its unique magnetic susceptibility. QSM provides improved contrast to noise ratio for certain tissues and structures compared to its magnitude counterpart. More importantly, magnetic susceptibility is a direct reflection of the molecular composition and cellular architecture of the tissue. Consequently, by quantifying magnetic susceptibility, QSM is becoming a quantitative imaging approach for characterizing normal and pathological tissue properties. This article reviews the mechanism generating susceptibility contrast within tissues and some associated applications. PMID:26844301

  5. Magnetic resonance characteristics and susceptibility weighted imaging of the brain in gadolinium encephalopathy.

    Science.gov (United States)

    Samardzic, Dejan; Thamburaj, Krishnamoorthy

    2015-01-01

    To report the brain imaging features on magnetic resonance imaging (MRI) in inadvertent intrathecal gadolinium administration. A 67-year-old female with gadolinium encephalopathy from inadvertent high dose intrathecal gadolinium administration during an epidural steroid injection was studied with multisequence 3T MRI. T1-weighted imaging shows pseudo-T2 appearance with diffusion of gadolinium into the brain parenchyma, olivary bodies, and membranous labyrinth. Nulling of cerebrospinal fluid (CSF) signal is absent on fluid attenuation recovery (FLAIR). Susceptibility-weighted imaging (SWI) demonstrates features similar to subarachnoid hemorrhage. CT may demonstrate a pseudo-cerebral edema pattern given the high attenuation characteristics of gadolinium. Intrathecal gadolinium demonstrates characteristic imaging features on MRI of the brain and may mimic subarachnoid hemorrhage on susceptibility-weighted imaging. Identifying high dose gadolinium within the CSF spaces on MRI is essential to avoid diagnostic and therapeutic errors. Copyright © 2013 by the American Society of Neuroimaging.

  6. AC susceptibility enhancement studies in magnetic systems

    International Nuclear Information System (INIS)

    Mukherjee, S.; Ranganathan, R.; Chakravarti, A.; Sil, S.

    2001-01-01

    Enhancement of AC susceptibility has been observed for typical ferromagnets (Gd), reentrant spin glasses like (Fe 1.5 Mn 1.5 Si) and canted spin systems (Ce(Fe 0.96 Al 0.04 ) 2 ). The data have been interpreted with the help of a simulation model based on dry friction-like pinning of domain walls for systems having ferromagnetic domain structures. A strong pinning mechanism appears in the reentrant spin glass like and canted spin systems at low temperatures in addition to the intrinsic one in the ferromagnetic phase. The temperature variation of the pinning potential has been given qualitatively for the reentrant spin glass like systems

  7. Magnetic and structural properties of an octanuclear Cu(II) S=1/2 mesoscopic ring: Susceptibility and NMR measurements

    International Nuclear Information System (INIS)

    Lascialfari, A.; Jang, Z. H.; Borsa, F.; Gatteschi, D.; Cornia, A.; Rovai, D.; Caneschi, A.; Carretta, P.

    2000-01-01

    Magnetic susceptibility, 1 H NMR and 63 Cu NMR-NQR experiments on two slightly different species of the molecular S=1/2 antiferromagnetic (AF) ring Cu8, [Cu 8 (dmpz) 8 (OH) 8 ]·2C 5 H 5 N (Cu8P) and [Cu 8 (dmpz) 8 (OH) 8 ]·2C 5 H 5 NO 2 (Cu8N), are presented. The magnetic energy levels are calculated exactly for an isotropic Heisenberg model Hamiltonian in zero magnetic field. From the magnetic susceptibility measurements we estimate the AF exchange coupling constant J∼1000 K and the resulting gap Δ∼500 K between the S T =0 ground state and the S T =1 first excited state. The 63,65 Cu NQR spectra indicate the presence of four crystallographically inequivalent copper nuclei in each ring. From the combination of the 63 Cu NQR spectra and of the 63 Cu NMR spectra at high magnetic field, we estimate the quadrupole coupling constant v Q of each site and the average asymmetry parameter η of the electric-field gradient tensor. The nuclear spin-lattice relaxation rate (NSLR) decreases exponentially on decreasing temperature for all nuclei investigated. The gap parameter extracted from 63 Cu NQR-NSLR is the same as for the susceptibility while a smaller value is obtained from the 63 Cu NMR-NSLR in an external magnetic field of 8.2 T. (c) 2000 The American Physical Society

  8. Experimental investigation of temperature dependence of the magnetic susceptibility (T) of manganites La1-xAxMnO3

    International Nuclear Information System (INIS)

    Salakhitdinova, M.; Kuvandikov, O.; Shakarov, Kh.; Shodiev, Z.

    2007-01-01

    Full text: he interest to lanthanoid manganites is based that enormous magnetoresistance is found in them and this materials are capable to test diverse structural and magnetic phase transformations. The work is devoted to experimental investigation of temperature dependence of the magnetic susceptibility (T) of manganites La 1-x A x MnO 3 which doped with Ag, K, Sr metals in wide temperature interval 50-8500 C, as well as to determination of their magnetic characteristics from this dependence. The dependence (T) was measured by the Faraday method with high-temperature magnetic pendulum balance in the atmosphere of refined helium. Maximal relative error of the measurements did not exceed 3 %. The analysis of experimental (T) dependence of investigated manganites has shown that the rise of stoichiometric rate of doped metals the temperature dependence of magnetic susceptibility of manganites monotonously is decreased. (authors)

  9. Polarized Neutron Diffraction as a Tool for Mapping Molecular Magnetic Anisotropy: Local Susceptibility Tensors in Co(II) Complexes.

    Science.gov (United States)

    Ridier, Karl; Gillon, Béatrice; Gukasov, Arsen; Chaboussant, Grégory; Cousson, Alain; Luneau, Dominique; Borta, Ana; Jacquot, Jean-François; Checa, Ruben; Chiba, Yukako; Sakiyama, Hiroshi; Mikuriya, Masahiro

    2016-01-11

    Polarized neutron diffraction (PND) experiments were carried out at low temperature to characterize with high precision the local magnetic anisotropy in two paramagnetic high-spin cobalt(II) complexes, namely [Co(II) (dmf)6 ](BPh4 )2 (1) and [Co(II) 2 (sym-hmp)2 ](BPh4 )2 (2), in which dmf=N,N-dimethylformamide; sym-hmp=2,6-bis[(2-hydroxyethyl)methylaminomethyl]-4-methylphenolate, and BPh4 (-) =tetraphenylborate. This allowed a unique and direct determination of the local magnetic susceptibility tensor on each individual Co(II) site. In compound 1, this approach reveals the correlation between the single-ion easy magnetization direction and a trigonal elongation axis of the Co(II) coordination octahedron. In exchange-coupled dimer 2, the determination of the individual Co(II) magnetic susceptibility tensors provides a clear outlook of how the local magnetic properties on both Co(II) sites deviate from the single-ion behavior because of antiferromagnetic exchange coupling. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. A semimetal model of the normal state magnetic susceptibility and transport properties of Ba(Fe1-xCox)2As2

    International Nuclear Information System (INIS)

    Sales, B.C.; McGuire, M.A.; Sefat, A.S.; Mandrus, D.

    2010-01-01

    A simple two-band 3D model of a semimetal is constructed to determine which normal state features of the Ba(Fe 1-x Co x ) 2 As 2 superconductors can be qualitatively understood within this framework. The model is able to account in a semiquantitative fashion for the measured magnetic susceptibility, Hall, and Seebeck data, and the low temperature Sommerfeld coefficient for 0 < x < 0.3 with only three parameters for all x. The purpose of the model is not to fit the data but to provide a simple starting point for thinking about the physics of these interesting materials. Although many of the static magnetic properties, such as the increase of the magnetic susceptibility with temperature, are reproduced by the model, none of the spin-fluctuation dynamics are addressed. A general conclusion from the model is that the magnetic susceptibility of most semimetals should increase with temperatures.

  11. Microstructural characterisation and change in a.c. magnetic susceptibility of duplex stainless steel during spinodal decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Lo, K.H., E-mail: KHLO@umac.m [Department of Electromechanical Engineering, University of Macau, Macau (China); Department of Physics and Materials Science, City University of Hong Kong (Hong Kong); Lai, J.K.L. [Department of Physics and Materials Science, City University of Hong Kong (Hong Kong)

    2010-06-15

    The microstructural changes during long-term (up to 10,000 h) spinodal decomposition in a duplex stain less steel, 7MoPLUS, have been characterised using TEM, a.c. magnetic susceptibility, X-ray diffractometry, microhardness measurement and optical microscopy. The microstructural changes and deformation microstructures of ferrite and austenite upon spinodal decomposition are characterised. The use of a.c. magnetic susceptibility to study the progress of spinodal decomposition is discussed. Above 450 {sup o}C, recent research by K.L. Weng et al. Mater. Sci. Eng. A 379 (2004) 119 has established that spinodal decomposition leads to crisscrossing of dislocations and the development of mottled contrast in the ferrite phase. The present work has shown that at 350 {sup o}C (the low-end of the spinodal range), crisscrossing of dislocations still occurs, but mottled contrast is absent. The G phase tends to be in contact with dislocations and its precipitation lags behind the occurrence of spinodal decomposition. No noticeable microstructural changes could be observed in the austenite phase in the spinodal temperature regime.

  12. Outlining precision boundaries among areas with different variability standards using magnetic susceptibility and geomorphic surfaces

    OpenAIRE

    Matias,Sammy S. R.; Marques Júnior,José; Siqueira,Diego S.; Pereira,Gener T.

    2014-01-01

    There is an increasing demand for detailed maps that represent in a simplified way the knowledge of the variability of a particular area or region maps. The objective was to outline precision boundaries among areas with different accuracy variability standards using magnetic susceptibility and geomorphic surfaces. The study was conducted in an area of 110 ha, which identified three compartment landscapes based on the geomorphic surfaces model. To determinate pH, organic matter, phosphorus, po...

  13. 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.

  14. Relationships between magnetic susceptibility and heavy metals in urban topsoils in the arid region of Isfahan, central Iran

    Science.gov (United States)

    Karimi, Rezvan; Ayoubi, Shamsollah; Jalalian, Ahmad; Sheikh-Hosseini, Ahmad Reza; Afyuni, Majid

    2011-05-01

    Recently methods dealing with magnetometry have been proposed as a proper proxy for assessing the heavy metal pollution of soils. A total of 113 topsoil samples were collected from public parks and green strips along the rim of roads with high-density traffic within the city of Isfahan, central Iran. The magnetic susceptibility (χ) of the collected soil samples was measured at both low and high frequency (χlf and χhf) using the Bartington MS2 dual frequency sensor. As, Cd, Cr, Ba, Cu, Mn, Pb, Zn, Sr and V concentrations were measured in the all collected soil samples. Significant correlations were found between Zn and Cu (0.85) and between Zn and Pb (0.84). The χfd value of urban topsoil varied from 0.45% to 7.7%. Low mean value of χfd indicated that the magnetic properties of the samples are predominately contributed by multi-domain grains, rather than by super-paramagnetic particles. Lead, Cu, Zn, and Ba showed positive significant correlations with magnetic susceptibility, but As, Sr, Cd, Mn, Cr and V, had no significant correlation with the magnetic susceptibility. There was a significant correlation between pollution load index (PLI) and χlf. PLI was computed to evaluate the soil environmental quality of selected heavy metals. Moreover, the results of multiple regression analysis between χlf and heavy metal concentrations indicated the LnPb, V and LnCu could explain approximately 54% of the total variability of χlf in the study area. These results indicate the potential of the magnetometric methods to evaluate the heavy metal pollution of soils.

  15. Measurements of temperature dependence of 'localized susceptibility'

    CERN Document Server

    Shiozawa, H; Ishii, H; Takayama, Y; Obu, K; Muro, T; Saitoh, Y; Matsuda, T D; Sugawara, H; Sato, H

    2003-01-01

    The magnetic susceptibility of some rare-earth compounds is estimated by measuring magnetic circular dichroism (MCD) of rare-earth 3d-4f absorption spectra. The temperature dependence of the magnetic susceptibility obtained by the MCD measurement is remarkably different from the bulk susceptibility in most samples, which is attributed to the strong site selectivity of the core MCD measurement.

  16. Quantitative Susceptibility Mapping Indicates a Disturbed Brain Iron Homeostasis in Neuromyelitis Optica - A Pilot Study.

    Directory of Open Access Journals (Sweden)

    Thomas Martin Doring

    Full Text Available Dysregulation of brain iron homeostasis is a hallmark of many neurodegenerative diseases and can be associated with oxidative stress. The objective of this study was to investigate brain iron in patients with Neuromyelitis Optica (NMO using quantitative susceptibility mapping (QSM, a quantitative iron-sensitive MRI technique. 12 clinically confirmed NMO patients (6 female and 6 male; age 35.4y±14.2y and 12 age- and sex-matched healthy controls (7 female and 5 male; age 33.9±11.3y underwent MRI of the brain at 3 Tesla. Quantitative maps of the effective transverse relaxation rate (R2* and magnetic susceptibility were calculated and a blinded ROI-based group comparison analysis was performed. Normality of the data and differences between patients and controls were tested by Kolmogorov-Smirnov and t-test, respectively. Correlation with age was studied using Spearman's rank correlation and an ANCOVA-like analysis. Magnetic susceptibility values were decreased in the red nucleus (p0.95; between -15 and -22 ppb depending on reference region with a trend toward increasing differences with age. R2* revealed significantly decreased relaxation in the optic radiations of five of the 12 patients (p<0.0001; -3.136±0.567 s-1. Decreased relaxation in the optic radiation is indicative for demyelination, which is in line with previous findings. Decreased magnetic susceptibility in the red nucleus is indicative for a lower brain iron concentration, a chemical redistribution of iron into less magnetic forms, or both. Further investigations are necessary to elucidate the pathological cause or consequence of this finding.

  17. Magnetic studies of dusts in the urban environment

    International Nuclear Information System (INIS)

    Xie, S.

    2000-12-01

    Dusts are one of the major public health concerns in the urban environment. This study investigates the application of magnetic techniques in the studies of urban dust pollution. Measurements of magnetic properties, element concentrations, and the organic matter content were carried out on Liverpool (UK) street dust and/or Bootle (UK) deposited dust. Mixed dominant ferrimagnetic phases are found in Liverpool street dust although magnetite is probably a major one. The partial susceptibility technique is able to model the contributions of main magnetic components satisfactorily in Liverpool street dust. There are similar spatial distributions for some measurements, such as χLF and Pb, whilst there are different patterns for some measurements, such as χLF and the organic matter content. There are good linear correlations between the organic matter content and some magnetic mineral concentration-related parameters for < 1mm (bulk) samples. Among them, frequency dependent susceptibility (χFD) shows the highest correlation coefficient value. χFD percentage demonstrates a significant correlation with the organic matter content for size fraction and bulk samples. This suggests that re-entrainment of soil is probably a major source of the organic material present in street dust. The ratio χARM /SIRM shows a highly significant correlation with the organic matter content for <150μm fraction samples. The study demonstrates that the simple, rapid, and non-destructive magnetic measurements may be used as proxies for the organic matter content in street dust. Associations between magnetic properties and element concentrations are investigated by using correlation analysis and factor analysis, which may be a potential approach for source identification of magnetic material in the environment. The study suggests that ferrimagnetic minerals are the dominant magnetic component in Bootle dust samples. Both studied sites show similar magnetic properties, but they can be

  18. Magnetic susceptibility correlation of km-thick Eifelian–Frasnian sections (Ardennes and Moravia)

    Czech Academy of Sciences Publication Activity Database

    Boulvain, F.; da Silva, A.C.; Mabille, C.; Hladil, Jindřich; Geršl, M.; Koptíková, Leona; Schnabl, Petr

    2010-01-01

    Roč. 13, č. 4 (2010), s. 309-318 ISSN 1374-8505 R&D Projects: GA AV ČR IAA300130702; GA AV ČR IAAX00130702 Institutional research plan: CEZ:AV0Z30130516 Keywords : Devonian limestone * magnetic susceptibility * Moravian Karst * Ardennes Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.645, year: 2010 http://popups.ulg.ac.be/Geol/docannexe.php?id=3181

  19. Susceptibility-Weighted Imaging and Quantitative Susceptibility Mapping in the Brain

    Science.gov (United States)

    Liu, Chunlei; Li, Wei; Tong, Karen A.; Yeom, Kristen W.; Kuzminski, Samuel

    2015-01-01

    Susceptibility-weighted imaging (SWI) is a magnetic resonance imaging (MRI) technique that enhances image contrast by using the susceptibility differences between tissues. It is created by combining both magnitude and phase in the gradient echo data. SWI is sensitive to both paramagnetic and diamagnetic substances which generate different phase shift in MRI data. SWI images can be displayed as a minimum intensity projection that provides high resolution delineation of the cerebral venous architecture, a feature that is not available in other MRI techniques. As such, SWI has been widely applied to diagnose various venous abnormalities. SWI is especially sensitive to deoxygenated blood and intracranial mineral deposition and, for that reason, has been applied to image various pathologies including intracranial hemorrhage, traumatic brain injury, stroke, neoplasm, and multiple sclerosis. SWI, however, does not provide quantitative measures of magnetic susceptibility. This limitation is currently being addressed with the development of quantitative susceptibility mapping (QSM) and susceptibility tensor imaging (STI). While QSM treats susceptibility as isotropic, STI treats susceptibility as generally anisotropic characterized by a tensor quantity. This article reviews the basic principles of SWI, its clinical and research applications, the mechanisms governing brain susceptibility properties, and its practical implementation, with a focus on brain imaging. PMID:25270052

  20. Susceptibility-weighted imaging and quantitative susceptibility mapping in the brain.

    Science.gov (United States)

    Liu, Chunlei; Li, Wei; Tong, Karen A; Yeom, Kristen W; Kuzminski, Samuel

    2015-07-01

    Susceptibility-weighted imaging (SWI) is a magnetic resonance imaging (MRI) technique that enhances image contrast by using the susceptibility differences between tissues. It is created by combining both magnitude and phase in the gradient echo data. SWI is sensitive to both paramagnetic and diamagnetic substances which generate different phase shift in MRI data. SWI images can be displayed as a minimum intensity projection that provides high resolution delineation of the cerebral venous architecture, a feature that is not available in other MRI techniques. As such, SWI has been widely applied to diagnose various venous abnormalities. SWI is especially sensitive to deoxygenated blood and intracranial mineral deposition and, for that reason, has been applied to image various pathologies including intracranial hemorrhage, traumatic brain injury, stroke, neoplasm, and multiple sclerosis. SWI, however, does not provide quantitative measures of magnetic susceptibility. This limitation is currently being addressed with the development of quantitative susceptibility mapping (QSM) and susceptibility tensor imaging (STI). While QSM treats susceptibility as isotropic, STI treats susceptibility as generally anisotropic characterized by a tensor quantity. This article reviews the basic principles of SWI, its clinical and research applications, the mechanisms governing brain susceptibility properties, and its practical implementation, with a focus on brain imaging. © 2014 Wiley Periodicals, Inc.

  1. Magnetic and structural properties of an octanuclear Cu(II) S=1/2 mesoscopic ring: Susceptibility and NMR measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lascialfari, A. [Department of Physics ' ' A. Volta' ' and Unita INFM, University of Pavia, Via Bassi 6, I-27100 Pavia, (Italy); Jang, Z. H. [Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States); Borsa, F. [Department of Physics ' ' A. Volta' ' and Unita INFM, University of Pavia, Via Bassi 6, I-27100 Pavia, (Italy); Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States); Gatteschi, D. [Department of Chemistry, University of Florence, Via Maragliano 77, I-50144 Florence, (Italy); Cornia, A. [Department of Chemistry, University of Modena, Via Campi 183, I-41100 Modena, (Italy); Rovai, D. [Department of Chemistry, University of Florence, Via Maragliano 77, I-50144 Florence, (Italy); Caneschi, A. [Department of Chemistry, University of Florence, Via Maragliano 77, I-50144 Florence, (Italy); Carretta, P. [Department of Physics ' ' A. Volta' ' and Unita INFM, University of Pavia, Via Bassi 6, I-27100 Pavia, (Italy)

    2000-03-01

    Magnetic susceptibility, {sup 1}H NMR and {sup 63}Cu NMR-NQR experiments on two slightly different species of the molecular S=1/2 antiferromagnetic (AF) ring Cu8, [Cu{sub 8}(dmpz){sub 8}(OH){sub 8}]{center_dot}2C{sub 5}H{sub 5}N (Cu8P) and [Cu{sub 8}(dmpz){sub 8}(OH){sub 8}]{center_dot}2C{sub 5}H{sub 5}NO{sub 2} (Cu8N), are presented. The magnetic energy levels are calculated exactly for an isotropic Heisenberg model Hamiltonian in zero magnetic field. From the magnetic susceptibility measurements we estimate the AF exchange coupling constant J{approx}1000 K and the resulting gap {delta}{approx}500 K between the S{sub T}=0 ground state and the S{sub T}=1 first excited state. The {sup 63,65}Cu NQR spectra indicate the presence of four crystallographically inequivalent copper nuclei in each ring. From the combination of the {sup 63}Cu NQR spectra and of the {sup 63}Cu NMR spectra at high magnetic field, we estimate the quadrupole coupling constant v{sub Q} of each site and the average asymmetry parameter {eta} of the electric-field gradient tensor. The nuclear spin-lattice relaxation rate (NSLR) decreases exponentially on decreasing temperature for all nuclei investigated. The gap parameter extracted from {sup 63}Cu NQR-NSLR is the same as for the susceptibility while a smaller value is obtained from the {sup 63}Cu NMR-NSLR in an external magnetic field of 8.2 T. (c) 2000 The American Physical Society.

  2. The influence of molecular order and microstructure on the R2* and the magnetic susceptibility tensor.

    Science.gov (United States)

    Wisnieff, Cynthia; Liu, Tian; Wang, Yi; Spincemaille, Pascal

    2016-06-01

    In this work, we demonstrate that in the presence of ordered sub-voxel structure such as tubular organization, biomaterials with molecular isotropy exhibits only apparent R2* anisotropy, while biomaterials with molecular anisotropy exhibit both apparent R2* and susceptibility anisotropy by means of susceptibility tensor imaging (STI). To this end, R2* and STI from gradient echo magnitude and phase data were examined in phantoms made from carbon fiber and Gadolinium (Gd) solutions with and without intrinsic molecular order and sub-voxel structure as well as in the in vivo brain. Confidence in the tensor reconstructions was evaluated with a wild bootstrap analysis. Carbon fiber showed both apparent anisotropy in R2* and anisotropy in STI, while the Gd filled capillary tubes only showed apparent anisotropy on R2*. Similarly, white matter showed anisotropic R2* and magnetic susceptibility with higher confidence, while the cerebral veins displayed only strong apparent R2* tensor anisotropy. Ordered sub-voxel tissue microstructure leads to apparent R2* anisotropy, which can be found in both white matter tracts and cerebral veins. However, additional molecular anisotropy is required for magnetic susceptibility anisotropy, which can be found in white matter tracts but not in cerebral veins. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Size and diluted magnetic properties of diamond shaped graphene quantum dots: Monte Carlo study

    Science.gov (United States)

    Masrour, R.; Jabar, A.

    2018-05-01

    The magnetic properties of diamond shaped graphene quantum dots have been investigated by varying their sizes with the Monte Carlo simulation. The magnetizations and magnetic susceptibilities have been studied with dilutions x (magnetic atom), several sizes L (carbon atom) and exchange interaction J between the magnetic atoms. The all magnetic susceptibilities have been situated at the transitions temperatures of each parameters. The obtained values increase when increases the values of x, L and J. The effect of exchanges interactions and crystal field on the magnetization has been discussed. The magnetic hysteresis cycles for several dilutions x, sizes L, exchange interactions J and temperatures T. The magnetic coercive increases with increasing the exchange interactions and decreases when the temperatures values increasing.

  4. Slope and Land Use Changing Effects on Soil Properties and Magnetic Susceptibility in Hilly Lands, Yasouj Region

    Directory of Open Access Journals (Sweden)

    rouhollaah vafaeezadeh

    2017-02-01

    Full Text Available Introduction: Land use changes are the most reasons which affect natural ecosystem protection. Forest soils have high organic matter and suitable structure, but their land use management change usually affects soil properties and decreases soil quality. There are several outcomes of such land use changes and intensification: accelerated soil erosion and decline of soil nutrient conditions, change of hydrological regimes and sedimentation and loss of primary forests and their biodiversity. Establishing effects of land use and land cover changes on soil properties have implications for devising management strategies for sustainable use. Forest land use change in Yasouj caused soil losses and decreased soil quality. The objectives of this study were to assess some soil physical and chemical properties and soil magnetic susceptibility changes in different land uses and slope position. Materials and Methods: Soil samples were taken from natural forest, degraded forest and dryland farm from different slops (0-10, 10-20 and 20-30 percent in sout east of Yasouj. They were from 0–10 cm depth in a completely randomized design with five replications. Soil moisture and temperature regimes in the study area are xeric and mesic, respectively. Particle size distribution was determined by the hydrometer method and soil organic matter, CaCO3 equivalent and bulk density was determined using standard procedures described in Methods of Soil Analysis book. Magnetic susceptibility was measured at low and high frequency of 0.46 kHz (χlf and 4.6 kHz (χHf respectively with a Bartington MS2D meter using approximately 20 g of soil held in a four-dram clear plastic vial. Frequency dependent susceptibility (χfd is expressed as the difference between the high and the low frequency measurements as a percentage of χ at low frequency. Results and Discussion: Soil texture was affected by land use change from silty clay loam in forest to silty loam in dry land farm

  5. Monte Carlo study of the magnetic properties in a bilayer dendrimer structure with non-magnetic layers

    Science.gov (United States)

    Jabar, A.; Masrour, R.

    2017-12-01

    In this paper, we study the Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions and magnetic layer effects on the bilayer transitions of a spin-5/2 Blume-Capel model formed by two magnetic blocs separated by a non-magnetic spacer of finite thickness. The thermalization process of magnetization for systems sizes has been given. We have shown that the magnetic order in the two magnetic blocs depend on the thickness of the magnetic layer. In the total magnetization profiles, the susceptibility peaks correspond to the reduced critical temperature. This critical temperature is displaced towards higher temperatures when increasing the number of magnetic layers. In addition, we have discussed and interpreted the behaviors of the magnetic hysteresis loops.

  6. Quantitative susceptibility mapping of human brain at 3T: a multisite reproducibility study.

    Science.gov (United States)

    Lin, P-Y; Chao, T-C; Wu, M-L

    2015-03-01

    Quantitative susceptibility mapping of the human brain has demonstrated strong potential in examining iron deposition, which may help in investigating possible brain pathology. This study assesses the reproducibility of quantitative susceptibility mapping across different imaging sites. In this study, the susceptibility values of 5 regions of interest in the human brain were measured on 9 healthy subjects following calibration by using phantom experiments. Each of the subjects was imaged 5 times on 1 scanner with the same procedure repeated on 3 different 3T systems so that both within-site and cross-site quantitative susceptibility mapping precision levels could be assessed. Two quantitative susceptibility mapping algorithms, similar in principle, one by using iterative regularization (iterative quantitative susceptibility mapping) and the other with analytic optimal solutions (deterministic quantitative susceptibility mapping), were implemented, and their performances were compared. Results show that while deterministic quantitative susceptibility mapping had nearly 700 times faster computation speed, residual streaking artifacts seem to be more prominent compared with iterative quantitative susceptibility mapping. With quantitative susceptibility mapping, the putamen, globus pallidus, and caudate nucleus showed smaller imprecision on the order of 0.005 ppm, whereas the red nucleus and substantia nigra, closer to the skull base, had a somewhat larger imprecision of approximately 0.01 ppm. Cross-site errors were not significantly larger than within-site errors. Possible sources of estimation errors are discussed. The reproducibility of quantitative susceptibility mapping in the human brain in vivo is regionally dependent, and the precision levels achieved with quantitative susceptibility mapping should allow longitudinal and multisite studies such as aging-related changes in brain tissue magnetic susceptibility. © 2015 by American Journal of Neuroradiology.

  7. 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

  8. Quantitative Susceptibility Mapping of Human Brain Reflects Spatial Variation in Tissue Composition

    Science.gov (United States)

    Li, Wei; Wu, Bing; Liu, Chunlei

    2011-01-01

    Image phase from gradient echo MRI provides a unique contrast that reflects brain tissue composition variations, such as iron and myelin distribution. Phase imaging is emerging as a powerful tool for the investigation of functional brain anatomy and disease diagnosis. However, the quantitative value of phase is compromised by its nonlocal and orientation dependent properties. There is an increasing need for reliable quantification of magnetic susceptibility, the intrinsic property of tissue. In this study, we developed a novel and accurate susceptibility mapping method that is also phase-wrap insensitive. The proposed susceptibility mapping method utilized two complementary equations: (1) the Fourier relationship of phase and magnetic susceptibility; and (2) the first-order partial derivative of the first equation in the spatial frequency domain. In numerical simulation, this method reconstructed the susceptibility map almost free of streaking artifact. Further, the iterative implementation of this method allowed for high quality reconstruction of susceptibility maps of human brain in vivo. The reconstructed susceptibility map provided excellent contrast of iron-rich deep nuclei and white matter bundles from surrounding tissues. Further, it also revealed anisotropic magnetic susceptibility in brain white matter. Hence, the proposed susceptibility mapping method may provide a powerful tool for the study of brain physiology and pathophysiology. Further elucidation of anisotropic magnetic susceptibility in vivo may allow us to gain more insight into the white matter microarchitectures. PMID:21224002

  9. Magnetic susceptibility and electron–phonon (e–p) interaction in some U and Ce based heavy fermion (HF) systems

    International Nuclear Information System (INIS)

    Sahoo, J.; Shadangi, N.; Nayak, P.

    2015-01-01

    Here an attempt is made to explore the variation of magnetic susceptibility with temperature for different values of the position of f-level (d) and electron–phonon interaction (EPI) strength (r) in some U and Ce based heavy Fermion (HF) systems within Periodic Anderson Model (PAM) in the presence of a static magnetic field B and interaction of phonons with electrons of hybridization band. Since magnetic susceptibility χ is related to the f-electron occupation n ±σ f , the expression for the latter is analytically derived through f–f correlation function following the Green function technique of Zubarev. The numerical analysis of χ as a function of temperature ‘T’ is done for different values of d and r. The results show a good agreement with the experiments for some U and Ce based HFs. An explanation for the existence of a critical value of d w.r.t. E F for switching of nature of χ∼T from U to Ce based HF systems is provided. Our calculated value of the temperature T χmax corresponding to the peak position of χ for small values of hybridization constant γ=0.002 and 0.0036 coincides with the experimental value of 19 K for UPt 3 and 35 K for UPd 2 Al 3 reported by Frings et al. and Geibel et al. respectively. - Highlights: • Variation of magnetic susceptibility χ with temperature T is studied for some HF systems. • Periodic Anderson Model in presence of magnetic field and electron–phonon interaction is used for numerical evaluation. • The existence of a critical value of the position of f-level(d) is proposed for distinction between χ∼T behavior of U and Ce based HF systems. • Results obtained are in good agreement with the experimental observations for some Ce and U based HF systems. • Theoretically evaluated temperature corresponding to the peak value of χ matches with the experimental results of UPt 3 and UPd 2 Al 3

  10. 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.

  11. Symmetric Anderson impurity model: Magnetic susceptibility, specific heat and Wilson ratio

    Science.gov (United States)

    Zalom, Peter; Pokorný, Vladislav; Janiš, Václav

    2018-05-01

    We extend the spin-polarized effective-interaction approximation of the parquet renormalization scheme from Refs. [1,2] applied on the symmetric Anderson model by adding the low-temperature asymptotics of the total energy and the specific heat. We calculate numerically the Wilson ratio and determine analytically its asymptotic value in the strong-coupling limit. We demonstrate in this way that the exponentially small Kondo scale from the strong-coupling regime emerges in qualitatively the same way in the spectral function, magnetic susceptibility and the specific heat.

  12. Study on magnetic property and fracture behavior of magnetic materials

    International Nuclear Information System (INIS)

    Miya, Kenzo; Demachi, Kazuyuki; Aoto, Kazumi; Nagae, Yuji

    2002-04-01

    Establishment of evaluation methods of material degradation before crack initiation is needed very much to enhance the reliability of structural components. We remark magnetic methods in this report. Our objectives are to reveal the relation between degradation and magnetic property and to develop evaluation methods of material degradation, especially plastic deformation and stress corrosion cracking (SCC). In the former part of this report, evaluation methods for plastic deformation are discussed. At first, the study that shows the relation between the magnetic flux leakage and plastic deformation is reviewed. We developed the inverse analysis method of magnetization to specify the degradation distribution. Moreover, we propose inverse analysis of magnetic susceptibility for quantitative evaluation. In the latter part, the topic is SCC. We measured the magnetic flux leakage from the sample induced a SCC crack (Inconel 600). Inconel 600 is a paramagnetic material at room temperature but the sample shows ferromagnetic and the magnetic flux leakage was changed near the SCC crack. The possibility of detection of a SCC crack is shown by the inverse analysis result from the magnetic flux leakage. Finally, it is recognized by observation of the micro magnetic distributions by using a magnetic force microscope that the magnetization has relation with chromium depletion near grain boundaries and it is weak near the SCC crack. From these results, the magnetic method is very effective for evaluation of degradation. (author)

  13. In Situ Magnetic Susceptibility Variations at Two Contaminated Sites: Brandywine, MD and Bemidji, MN

    Science.gov (United States)

    Donaldson, Y. Y.; Kessouri, P.; Ntarlagiannis, D.; Johnson, T. C.; Day-Lewis, F. D.; Johnson, C. D.; Bekins, B. A.; Slater, L. D.

    2017-12-01

    Geophysical methods are widely used monitoring tools for investigating subsurface processes. Compared to more traditional methods, they are low cost and minimally invasive. Magnetic susceptibility (MS) is a geophysical technique particularly sensitive to the presence of ferri/ ferro-magnetic particles such as iron oxides (e.g., magnetite, hematite and goethite). These oxides can be formed through microbially mediated redox reactions, inducing changes in the soil properties that can be observed by MS measurements. Monitoring MS changes over time provides indications of iron mineral transformations in the ground. These transformations are of particular interest for the characterization of contaminated sites. We acquired borehole MS measurements from two contaminated sites: Brandywine, MD and Bemidji, MN. Active remediation was applied at Brandywine, whereas natural attenuation has been geophysically monitored at Bemidji since 2011 using MS log measurements. High MS values were observed at both sites within the contaminated area only. We hypothesize that this is due to iron reducing bacteria reducing Fe-(III) to Fe-(II) and utilizing contaminants and/or amendments injected as a carbon source. At Bemidji, elevated MS readings were observed in the smear zone and correlate to the presence of magnetite. Furthermore, time-lapse MS observations at Bemidji indicate a decay in signal amplitude over time suggesting further redox transformation into less magnetic particles. For both field examples presented here, we observe variations in magnetic susceptibility within the contaminated areas that can be linked with redox reactions and mineral transformations occurring during the degradation of organic contaminants.

  14. 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.

  15. Simultaneous MR quantification of hepatic fat content, fatty acid composition, transverse relaxation time and magnetic susceptibility for the diagnosis of non-alcoholic steatohepatitis.

    Science.gov (United States)

    Leporq, B; Lambert, S A; Ronot, M; Vilgrain, V; Van Beers, B E

    2017-10-01

    Non-alcoholic steatohepatitis (NASH) is characterized at histology by steatosis, hepatocyte ballooning and inflammatory infiltrates, with or without fibrosis. Although diamagnetic material in fibrosis and inflammation can be detected with quantitative susceptibility imaging, fatty acid composition changes in NASH relative to simple steatosis have also been reported. Therefore, our aim was to develop a single magnetic resonance (MR) acquisition and post-processing scheme for the diagnosis of steatohepatitis by the simultaneous quantification of hepatic fat content, fatty acid composition, T 2 * transverse relaxation time and magnetic susceptibility in patients with non-alcoholic fatty liver disease. MR acquisition was performed at 3.0 T using a three-dimensional, multi-echo, spoiled gradient echo sequence. Phase images were unwrapped to compute the B 0 field inhomogeneity (ΔB 0 ) map. The ΔB 0 -demodulated real part images were used for fat-water separation, T 2 * and fatty acid composition quantification. The external and internal fields were separated with the projection onto dipole field method. Susceptibility maps were obtained after dipole inversion from the internal field map with single-orientation Bayesian regularization including spatial priors. Method validation was performed in 32 patients with biopsy-proven, non-alcoholic fatty liver disease from which 12 had simple steatosis and 20 NASH. Liver fat fraction and T 2 * did not change significantly between patients with simple steatosis and NASH. In contrast, the saturated fatty acid fraction increased in patients with NASH relative to patients with simple steatosis (48 ± 2% versus 44 ± 4%; p magnetic susceptibility decreased (-0.30 ± 0.27 ppm versus 0.10 ± 0.14 ppm; p magnetic susceptibility as NASH marker was 0.91 (95% CI: 0.79-1.0). Simultaneous MR quantification of fat content, fatty acid composition, T 2 * and magnetic susceptibility is feasible in the liver. Our preliminary results

  16. Susceptibility investigation of the nanoparticle coating-layer effect on the particle interaction in biocompatible magnetic fluids

    International Nuclear Information System (INIS)

    Morais, P.C.; Santos, J.G.; Silveira, L.B.; Gansau, C.; Buske, N.; Nunes, W.C.; Sinnecker, J.P.

    2004-01-01

    AC susceptibility was used to investigate the effect of the surface-coating layer in two biocompatible, magnetite-based, magnetic fluid samples. Dextran and dimercaptosuccinic acid (DMSA) were the surface coating species. The temperature and frequency dependence of the peak susceptibility was discussed using the Vogel-Fulcher relation, from which the typical energy barrier (temperature correction) values of 1340±20 K (70±3 K) and 1230±30 K (86±5 K) were obtained for the dextran- and DMSA-coated nanoparticles, respectively

  17. Anisotropy of magnetic susceptibility (AMS) studies of Campanian ...

    Indian Academy of Sciences (India)

    trial, paralic and shallow marine strata. It com- prises of lower ... Sillakkudi sandstone was deposited under shallow ..... Jelinek V 1978 Statistical processing of anisotropy of mag- ... reorientation of magnetic fabrics in deep-sea sediments at.

  18. Monte Carlo study of the magnetic properties of GdSb alloys

    Energy Technology Data Exchange (ETDEWEB)

    Masrour, R., E-mail: rachidmasrour@hotmail.com [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, Sidi Bouzid, Safi, BP, 46000 63 (Morocco); LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Av. Ibn Batouta, B.P. 1014, Rabat (Morocco); Bahmad, L. [LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Av. Ibn Batouta, B.P. 1014, Rabat (Morocco); Hlil, E.K. [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble cedex 9 (France); Hamedoun, M. [Institute of Layers and Nanotechnologies, MAScIR, Rabat (Morocco); Benyoussef, A. [LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Av. Ibn Batouta, B.P. 1014, Rabat (Morocco); Institute of Layers and Nanotechnologies, MAScIR, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco)

    2014-03-15

    The magnetic properties of antiferromagnetic GdSb layers have been studied using Monte Carlo simulations within the Ising model framework. The considered Hamiltonian includes first nearest-neighbor, an external magnetic field and a crystal field. The thermal magnetizations and magnetic susceptibilities are computed for a fixed size. In addition, the Néel temperature is deduced. The magnetization versus the exchange interactions and crystal field are studied for a fixed system size, N=5, 7 and 9 sites. The magnetic hysteresis cycle versus temperature is also established. - Highlights: • Determination of the Néel temperature of GdSb by MC simulations. • Magnetic hysteresis cycle of GdSb. • Determination of saturation magnetization and field coercive in GdSb.

  19. Influence of the interaction between the inter- and intragranular magnetic responses in the analysis of the ac susceptibility of a granular FeSe0.5Te0.5 superconductor

    Science.gov (United States)

    Mancusi, D.; Polichetti, M.; Cimberle, M. R.; Pace, S.

    2015-09-01

    The temperature-dependent fundamental ac susceptibility of a granular superconductor in the absence of dc fields has been analyzed by developing a phenomenological model for effective magnetic fields, taking into account the influence of the magnetic interaction between the intergranular and the intragranular magnetizations due to demagnetizing effects. For this purpose a policrystal Fe-based superconductor FeSe0.5Te0.5 sample has been studied. By the frequency dependence of the peaks of the temperature-dependent imaginary part of the fundamental complex susceptibility, the dependence on temperature of the characteristic times both for intergranular and intragranular relaxations of magnetic flux are derived, and the corresponding relaxation processes due to combinations of the flux creep, the flux flow and the thermally activated flux flow regimes are identified on the basis of the effective magnetic fields both at the sample surface and at the grains’ surfaces. Such characteristic times, through the Havriliak-Negami function, determine the temperature and the frequency dependences of the complex susceptibility. The comparison of the numerically obtained curves with the experimental ones confirms the relevance, for identifying the intergranular and intragranular contributions to the ac magnetic response and the corresponding flux dynamical regimes, of the interaction between the intergranular and intragranular magnetizations due to demagnetizing effects.

  20. 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.

  1. Susceptibility tensor imaging and tractography of collagen fibrils in the articular cartilage.

    Science.gov (United States)

    Wei, Hongjiang; Gibbs, Eric; Zhao, Peida; Wang, Nian; Cofer, Gary P; Zhang, Yuyao; Johnson, G Allan; Liu, Chunlei

    2017-11-01

    To investigate the B 0 orientation-dependent magnetic susceptibility of collagen fibrils within the articular cartilage and to determine whether susceptibility tensor imaging (STI) can detect the 3D collagen network within cartilage. Multiecho gradient echo datasets (100-μm isotropic resolution) were acquired from fixed porcine articular cartilage specimens at 9.4 T. The susceptibility tensor was calculated using phase images acquired at 12 or 15 different orientations relative to B 0 . The susceptibility anisotropy of the collagen fibril was quantified and diffusion tensor imaging (DTI) was compared against STI. 3D tractography was performed to visualize and track the collagen fibrils with DTI and STI. STI experiments showed the distinct and significant anisotropic magnetic susceptibility of collagen fibrils within the articular cartilage. STI can be used to measure and quantify susceptibility anisotropy maps. Furthermore, STI provides orientation information of the underlying collagen network via 3D tractography. The findings of this study demonstrate that STI can characterize the orientation variation of collagen fibrils where diffusion anisotropy fails. We believe that STI could serve as a sensitive and noninvasive marker to study the collagen fibrils microstructure. Magn Reson Med 78:1683-1690, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  2. Measurement of magnetic susceptibility on tailings cores report on cores obtained from the Ontario Research Foundation lysimeter experiment

    International Nuclear Information System (INIS)

    1984-10-01

    Bulk susceptibility and induced magnetic remanence results are reported for 40 cores obtained from the uranium tailings lysimeter experiment at the Ontario Research Foundation. Both methods indicate a broad threefold subdivision of the tailings pile. An upper zone is characterized by an enhanced susceptibility level, which is related to enhanced concentration of both magnetite and hematite. Depletion zones, where present, are of limited areal extent and strongly developed. An intermediate zone is characterized by a mixture of large areas of reduced susceptibility that separate smaller regions of slightly enhanced susceptibility. The zones of susceptibility depletion appear to define a dendritic drainage pattern. Locally in this zone magnetite is enhanced and hematite depleted. In the lowermost zone susceptibility levels are reduced over most of the tailings bed. Only in the upper most right hand corner is there any vestige of a positive susceptibility concentration. Both magnetite and hematite are strongly depleted in this lower zone. Visually it is apparent that this lowermost depleted zone correlates to the zones of strongest 'yellowcake' development

  3. 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

    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 of a ...

  4. Avaliação da susceptibilidade magnética usando uma balança analítica Evaluation of the magnetic susceptibility using an analytical scale

    Directory of Open Access Journals (Sweden)

    Antonio Adilton O. Carneiro

    2003-12-01

    Full Text Available A simple system to measure the magnetic susceptibility of different materials is presented. The system uses an analytical scale with sensitivity on the order of micrograms and a permanent NdBFe magnet, based in the Rankine method. In this apparatus, the sample is placed near to the magnet that is fixed on the scale. Depending on the magnetic properties of the sample, an attractive or repulsive force will appear between the magnet and the magnetizing sample. Measuring this force, registered by the scale as a mass, the magnetic parameters such as: permeability and susceptibility of the sample can be determined. Despite it is simplicity the method is quantitative, precise and easily reproducible in many laboratories, what makes it attractive for teaching experiments.

  5. Magnetic properties of Ni/Au core/shell studied by Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Masrour, R., E-mail: rachidmasrour@hotmail.com [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, Sidi Bouzid, Safi, 63 4600 (Morocco); LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Av. Ibn Batouta, B.P. 1014, Rabat (Morocco); Bahmad, L. [LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Av. Ibn Batouta, B.P. 1014, Rabat (Morocco); Hamedoun, M. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Benyoussef, A. [LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Av. Ibn Batouta, B.P. 1014, Rabat (Morocco); Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco); Hlil, E.K. [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble cedex 9 (France)

    2014-01-10

    The magnetic properties of ferromagnetic Ni/Au core/shell have been studied using Monte Carlo simulations within the Ising model framework. The considered Hamiltonian includes the exchange interactions between Ni–Ni, Au–Au and Ni–Au and the external magnetic field. The thermal total magnetizations and total magnetic susceptibilities of core/shell Ni/Au are computed. The critical temperature is deduced. The exchange interaction between Ni and Au atoms is obtained. In addition, the total magnetizations versus the external magnetic field and crystal filed for different temperature are also established.

  6. Magnetic properties of carbonyl iron particles in magnetorheological fluids

    International Nuclear Information System (INIS)

    Gorodkin, S R; James, R O; Kordonski, W I

    2009-01-01

    Knowledge of the magnetic properties of dispersed magnetic particles is a prerequisite to the design an MR fluid with desired performance. A term specific susceptibility is introduced for characterization of particle susceptibility. The study was performed with the Bartington MS2B magnetic susceptibility system on small samples volume. Specific magnetic susceptibility of iron particles was found to be a linear function of median particle size. Structural change in the fluid, including particle organization, led to susceptibility drift and may affect fluid performance. It was shown that susceptibility data can be used for evaluation of the concentration of carbonyl iron particles in MR fluids.

  7. Interferometric study on the mass transfer in cryogenic distillation under magnetic field

    Science.gov (United States)

    Bao, S. R.; Zhang, R. P.; Y Rong, Y.; Zhi, X. Q.; Qiu, L. M.

    2017-12-01

    Cryogenic distillation has long been used for the mass production of industrial gases because of its features of high efficiency, high purity, and capability to produce noble gases. It is of great theoretical and practical significance to explore methods to improve the mass transfer efficiency in cryogenic distillation. The negative correlation between the susceptibility of paramagnetic oxygen and temperature provides a new possibility of comprehensive utilization of boiling point and susceptibility differences in cryogenic distillation. Starting from this concept, we proposed a novel distillation intensifying method by using gradient magnetic field, in which the magnetic forces enhance the transport of the oxygen molecules to the liquid phase in the distillation. In this study, a cryogenic testbed was designed and fabricated to study the diffusion between oxygen and nitrogen under magnetic field. A Mach-Zehnder interferometer was used to visualize the concentration distribution during the diffusion process. The mass transfer characteristics with and without magnetic field, in the chamber filled with the magnetized medium, were systematically studied. The concentration redistribution of oxygen was observed, and the stable stratified diffusion between liquid oxygen and nitrogen was prolonged by the non-uniform magnetic field. The experimental results show that the magnetic field can efficiently influence the mass transfer in cryogenic distillation, which can provide a new mechanism for the optimization of air separation process.

  8. High-order coupled cluster method study of frustrated and unfrustrated quantum magnets in external magnetic fields

    International Nuclear Information System (INIS)

    Farnell, D J J; Zinke, R; Richter, J; Schulenburg, J

    2009-01-01

    We apply the coupled cluster method (CCM) in order to study the ground-state properties of the (unfrustrated) square-lattice and (frustrated) triangular-lattice spin-half Heisenberg antiferromagnets in the presence of external magnetic fields. Approximate methods are difficult to apply to the triangular-lattice antiferromagnet because of frustration, and so, for example, the quantum Monte Carlo (QMC) method suffers from the 'sign problem'. Results for this model in the presence of magnetic field are rarer than those for the square-lattice system. Here we determine and solve the basic CCM equations by using the localized approximation scheme commonly referred to as the 'LSUBm' approximation scheme and we carry out high-order calculations by using intensive computational methods. We calculate the ground-state energy, the uniform susceptibility, the total (lattice) magnetization and the local (sublattice) magnetizations as a function of the magnetic field strength. Our results for the lattice magnetization of the square-lattice case compare well to the results from QMC approaches for all values of the applied external magnetic field. We find a value for the magnetic susceptibility of χ = 0.070 for the square-lattice antiferromagnet, which is also in agreement with the results from other approximate methods (e.g., χ = 0.0669 obtained via the QMC approach). Our estimate for the range of the extent of the (M/M s =) 1/3 magnetization plateau for the triangular-lattice antiferromagnet is 1.37 SWT = 0.0794. Higher-order calculations are thus suggested for both SWT and CCM LSUBm calculations in order to determine the value of χ for the triangular lattice conclusively.

  9. Magnetic susceptibility and electrical conductivity of metallic dental materials and their impact on MR imaging artifacts

    Czech Academy of Sciences Publication Activity Database

    Starčuková, Jana; Starčuk jr., Zenon; Hubálková, H.; Linetskiy, I.

    2008-01-01

    Roč. 24, č. 6 (2008), s. 715-723 ISSN 0109-5641 R&D Projects: GA MZd NR8110 Institutional research plan: CEZ:AV0Z20650511 Keywords : metallic dental materials * dental alloys * amalgams * MR imaging * magnetic susceptibility * electric conductivity * image artifact Subject RIV: FF - HEENT, Dentistry Impact factor: 2.941, year: 2008

  10. Crystal shape-dependent magnetic susceptibility and Curie law crossover in the spin ices Dy2Ti2O7 and Ho2Ti2O7

    International Nuclear Information System (INIS)

    Bovo, L; Bramwell, S T; Jaubert, L D C; Holdsworth, P C W

    2013-01-01

    We present an experimental determination of the isothermal magnetic susceptibility of the spin ice materials Dy 2 Ti 2 O 7 and Ho 2 Ti 2 O 7 in the temperature range 1.8–300 K. The use of spherical crystals has allowed accurate correction for demagnetizing fields and allowed the true bulk isothermal susceptibility χ T (T) to be estimated. This has been compared against a theoretical expression based on a Husimi tree approximation to the spin ice model. Agreement between experiment and theory is excellent at T > 10 K, but systematic deviations occur below that temperature. Our results largely resolve an apparent disagreement between neutron scattering and bulk measurements that has been previously noted. They also show that the use of non-spherical crystals in magnetization studies of spin ice may introduce very significant systematic errors, although we note some interesting—and possibly new—systematics concerning the demagnetizing factor in cuboidal samples. Finally, our results show how experimental susceptibility measurements on spin ices may be used to extract the characteristic energy scale of the system and the corresponding chemical potential for emergent magnetic monopoles. (paper)

  11. Micro-scale grain-size analysis and magnetic properties of coal-fired power plant fly ash and its relevance for environmental magnetic pollution studies

    Energy Technology Data Exchange (ETDEWEB)

    Blaha, U.; Sapkota, B.; Appel, E.; Stanjek, H.; Rosler, W. [University of Tubingen, Tubingen (Germany). Inst. of Geoscience

    2008-11-15

    Two fly ash samples from a black coal-fired power plant (Bexbach, Germany) were investigated for their magnetic properties, particle structure, grain-size distribution and chemical composition. Grain-size distribution was determined on bulk samples and on magnetic extracts. Magnetic susceptibility of different grain-size fractions was analyzed with respect to the according amount of fractions, high- and low-temperature dependence of magnetic susceptibility and thermal demagnetization of IRM identified magnetite and hematite as magnetic phases. Magnetic spherules were quantitatively extracted from bulk fly ash samples and examined using SEM/EDX analysis. Particle morphology and grain-size analysis on the magnetically extracted material were studied. Individual spherule types were identified and internal structures of selected polished particles were investigated by SEM and EDX analyses. Main element contents of the internal structures which consist of 'magnetite' crystals and 'glassy' matrix were systematically determined and statistically assessed. The chemical data of the micro-scale structures in the magnetic spherules were compared with XRF data from bulk material, revealing the relative element distribution in composed magnetic spherules. Comparison of the bulk sample grain-size (0.5-300 {mu}m) and grain-size spectra from magnetic extracts (1-186.5 {mu}m) shows that strongly magnetic particles mainly occur in the fine fractions of < 63 {mu}m. This study comprises a comprehensive characterization of coal-fired power plant fly ash, using magnetic, chemical, and microscopic methods. The results can serve as reference data for a variety of environmental magnetic studies.

  12. Anomalous magnetic susceptibility values and traces of subsurface microbial activity in carbonate banks on San Salvador Island, Bahamas

    Czech Academy of Sciences Publication Activity Database

    Hladil, Jindřich; Carew, J. L.; Mylroie, J. E.; Pruner, Petr; Kohout, Tomáš; Jell, J. S.; Lacka, B.; Langrová, Anna

    2004-01-01

    Roč. 50, č. 2 (2004), s. 161-182 ISSN 0172-9179 R&D Projects: GA AV ČR(CZ) IAA3013209 Keywords : carbonate rocks * magnetic susceptibility * subsurface microbial diagenesis Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.857, year: 2004

  13. High-field susceptibility in ferromagnetic NpOs2

    International Nuclear Information System (INIS)

    Dunlap, B.D.; Aldred, A.T.; Lam, D.J.; Davidson, G.R.

    1975-01-01

    NpOs 2 is known to be a ferromagnet with a Curie temperature of 7.5 0 K. Previous bulk magnetization measurements indicated a field-induced magnetization even well below the transition temperature. By a measurement of the local high-field susceptibility, using the Moessbauer effect in 237 Np, a susceptibility of (1.2 +- 0.2) x 10 -2 emu/mole at 1.6 0 K is obtained, in general agreement with the bulk measurement. Such a large susceptibility is best understood by a model f itinerant magnetism, although other properties of the material indicate localized behavior

  14. An experimental study of magnetic-field and temperature dependence on magnetic fluid’s heating power

    International Nuclear Information System (INIS)

    Beković, Miloš; Trlep, Mladen; Jesenik, Marko; Goričan, Viktor; Hamler, Anton

    2013-01-01

    This paper firstly presents a measurement system for determining the magnetic properties of magnetic fluids, based on three pickup coils. The accuracy of the system was tested on known samples and then used for the characterization of magnetic losses (heating power P) on the magnetic fluid sample using two different methods. The first method is based on determining the hysteresis loop area and the second on determining the complex susceptibility; and showed that both methods are equivalent. The aim of this paper was to identify the heating power of the liquid at a known value for the magnetic field, and the arbitrary temperature. Thus, we explored the actual reduction in the heating power due to the heating of the sample, which cannot be achieved without the temperature regulated heat bath using established calorimetric methods. -- Highlights: ► A new measurement system was tested with numerous samples, and results were promising. ► Magnetic fluid heating power was determined using a system of J-compensated coil. ► Complex susceptibility method results equal losses as hysteresis loops approach. ► Temperature dependent heating power was explored without the heath-bath . ► For larger magnetic fields a linear H dependence of heating power is revealed

  15. Zero-field-cooled/field-cooled magnetization study of Dendrimer model

    Energy Technology Data Exchange (ETDEWEB)

    Arejdal, M., E-mail: arejdal.achdad@gmail.com [Laboratory of Magnetism and Physics of High Energies, Department of Physics, L.M.P.H.E (URAC-12), Faculty of Sciences, Mohammed V University, Rabat (Morocco); Bahmad, L. [Laboratory of Magnetism and Physics of High Energies, Department of Physics, L.M.P.H.E (URAC-12), Faculty of Sciences, Mohammed V University, Rabat (Morocco); Benyoussef, A. [Hassan II Academy of Science and Technology, Rabat (Morocco)

    2017-01-01

    Being motivated by Dendrimer model with mixed spins σ=3 and S=7/2, we investigated the magnetic nanoparticle system in this study. We analyzed and discussed the ground-state phase diagrams and the stable phases. Then, we elaborated and explained the magnetic properties of the system by using Monte Carlo Simulations (MCS) in the framework of the Ising model. In this way, we determined the blocking temperature, which is deduced through studying the partial-total magnetization and susceptibility as a function of the temperature, and we established the effects of both the exchange coupling interaction and the crystal field on the hysteresis loop.

  16. Magnetic and Electrical Properties of Leachate

    Directory of Open Access Journals (Sweden)

    Kartika Kirana

    2011-11-01

    Full Text Available Heavy metals content as well as magnetic and electrical properties of leachate from Sarimukti, West Java were studied in an attempt to seek correlation between heavy metals content and magnetic/electrical properties. Such correlation is expected to open the way for the use of magnetic/electrical properties as proxy indicators for the concentration of heavy metals in the leachate. The number of leachate samples studied is 21; 15 were taken spatially at depth of 1 m while the remaining 6 samples were taken vertically at a particular point. Measurement results showed that the heavy metals content in the leachate has a smaller concentration, except for Fe. The correlation between magnetic susceptibility and heavy metals content was found to be not so significant. The best correlation coefficient between magnetic susceptibility with heavy metals in leachate was found in Zn. Correlation between electrical conductivity and heavy metal is also not so significant, except for Zn and Cd. The use of magnetic properties as proxy indicator for heavy metals content in leachate is plausible provided that the magnetic susceptibility exceeds certain threshold value. Correlation between magnetic susceptibility, electrical conductivity and heavy metal content would be good if each quantity has a large value.

  17. 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 optical gels.

  18. Neural - levelset shape detection segmentation of brain tumors in dynamic susceptibility contrast enhanced and diffusion weighted magnetic resonance images

    International Nuclear Information System (INIS)

    Vijayakumar, C.; Bhargava, Sunil; Gharpure, Damayanti Chandrashekhar

    2008-01-01

    A novel Neuro - level set shape detection algorithm is proposed and evaluated for segmentation and grading of brain tumours. The algorithm evaluates vascular and cellular information provided by dynamic contrast susceptibility magnetic resonance images and apparent diffusion coefficient maps. The proposed neural shape detection algorithm is based on the levels at algorithm (shape detection algorithm) and utilizes a neural block to provide the speed image for the level set methods. In this study, two different architectures of level set method have been implemented and their results are compared. The results show that the proposed Neuro-shape detection performs better in differentiating the tumor, edema, necrosis in reconstructed images of perfusion and diffusion weighted magnetic resonance images. (author)

  19. 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.

  20. Magnetic fabric and flow direction in the Ediacaran Imider dyke swarms (Eastern Anti-Atlas, Morocco), inferred from the Anisotropy of Magnetic Susceptibility (AMS)

    Science.gov (United States)

    Otmane, Khadija; Errami, Ezzoura; Olivier, Philippe; Berger, Julien; Triantafyllou, Antoine; Ennih, Nasser

    2018-03-01

    Located in the Imiter Inlier (Eastern Saghro, Anti-Atlas, Morocco), Ediacaran volcanic dykes have been studied for their petrofabric using Anisotropy of Magnetic Susceptibility (AMS) technique. Four dykes, namely TF, TD, FF and FE show andesitic compositions and are considered to belong to the same dyke swarm. They are oriented respectively N25E, N40E, N50E, and N10E and have been emplaced during a first tectonic event. The dyke FW, oriented N90E displays a composition of alkali basalt and its emplacement is attributed to a subsequent tectonic event. These rocks are propylitized under greenschist facies conditions forming a secondary paragenesis constituted by calcite, chlorite, epidote and sericite. The dykes TF, TD, FF and FE are sub-volcanic calc-alkaline, typical of post-collisional basalts/andesites, belonging to plate margin andesites. The FW dyke shows a within-plate basalt signature; alkaline affinity reflecting a different petrogenetic process. The thermomagnetic analyses show a dominantly ferromagnetic behaviour in the TF dyke core carried by single domain Ti-poor magnetite, maghemite and pyrrhotite. The dominantly paramagnetic susceptibilities in TF dyke rims and TD, FE, FF and FW dykes are controlled by ilmenite, amphibole, pyroxene and chlorite. The magnetic fabrics of the Imider dykes, determined by our AMS study, allows us to reconstitute the tectonic conditions which prevailed during the emplacement of these two generations of volcanic dykes. The first tectonic event was characterized by a roughly NE-SW compression and the second tectonic event is characterized by an E-W shortening followed by a relaxation recording the end of the Pan-African orogeny in the eastern Anti-Atlas.

  1. Downhole logs of natural gamma radiation and magnetic susceptibility and their use in interpreting lithostratigraphy in AND-1B, Antarctica

    Science.gov (United States)

    Williams, T.; Morin, R. H.; Jarrard, R. D.; Jackolski, C. L.; Henrys, S. A.; Niessen, F.; Magens, D.; Kuhn, G.; Monien, D.; Powell, R. D.

    2010-12-01

    The ANDRILL McMurdo Ice Shelf (MIS) project drilled 1285 metres of sediment representing the last 14 million years of glacial history. Downhole geophysical logs were acquired to a depth of 1018 metres, and are complementary to data acquired from the core itself. We describe here the natural gamma radiation (NGR) and magnetic susceptibility logs, and their application to understanding lithological and paleoenvironmental change at ANDRILL McMurdo Ice Shelf Hole AND-1B. Natural gamma radiation logs cover the whole interval from the sea floor to 1018 metres, and magnetic susceptibility and other logs covered the open-hole intervals between 692-1018 and 237-342 metres. NGR logs were stacked and corrected for signal attenuation through the drill pipe, and magnetic susceptibility logs were corrected for drift. In the upper part of AND-1B, clear alternations between low and high NGR values distinguish between diatomite (lacking minerals containing naturally radioactive K, U, and Th) and diamict (containing K-bearing clays, K-feldspar, and heavy minerals). In the lower open-hole logged section, NGR and magnetic susceptibility can also distinguish claystones (rich in K-bearing clay minerals, relatively low in magnetite) and diamicts (relatively high in magnetite), while sandstones generally have high resistivity log values at AND-1B. On the basis of these three downhole logs, three sets of facies can be predicted correctly for 74% of the 692-1018m interval. The logs were then used to predict facies for the 7% of this interval that was unrecovered by coring. Similarly, the NGR log provides the best information on the lithology of the poorly recovered top 25m of AND-1B. Given the understanding of the physical property characteristics of different facies, it is also possible to identify subtle changes in lithology from the physical properties, and help refine parts of the lithostratigraphy (for example, the varying terrigenous content of diatomites).

  2. A high sensitivity SQUID-method for the measurement of magnetic susceptibility of small samples in the temperature range 1.5 K-40 K and application on small palladium particles

    International Nuclear Information System (INIS)

    Tu Nguyen Quang.

    1979-01-01

    In this paper a method is developed for magnetic susceptibility measurements which is superior to the common methods. The method is based on the SQUID-principle (Superconducting Quantum Interference Device) using the tunnel effect of a superconducting point contact and magnetic flux quantization for measuring electric and magnetic quantities. Due to this refined method susceptibility changes of very small palladium particles could be detected in the temperature range 1.5 K-40 K with respect to the bulk. In addition susceptibility differences of particle distributions with different means diameters (81 Angstroem and 65 Angstroem) have been measured for the first time. A quantitative comparison of the measurements with theoretical results shows satisfactory agreement. (orig./WBU) [de

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

    International Nuclear Information System (INIS)

    Renshaw, P.F.; Levin, J.M.; Kaufman, M.J.; Ross, M.H.; Lewis, R.F.; Harris, G.J.

    1997-01-01

    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.)

  4. Ab initio quantum chemical calculation as a tool of evaluating diamagnetic susceptibility of magnetically levitating substances

    International Nuclear Information System (INIS)

    Fujiwara, Y; Tanimoto, Y

    2009-01-01

    On magnetic force evaluation necessary for magnetically levitated diamagnetic substances, isotropic diamagnetic susceptibility estimation by the ab initio quantum chemical calculation using Gaussian03W was verified for more than 300 molecules in a viewpoint of the accuracy in the absolute value and the calculation level affording good cost performance. From comparison, the method of B3PW91 / 6-311+G(d,p) was found to give the adequate absolute value by the relation of (observed) = (1.03 ± 0.005) x (calculated) - (1.22 ± 0.60) x 10 -6 in a unit of cm 3 mol -1 and good cost performance.

  5. Ab initio quantum chemical calculation as a tool of evaluating diamagnetic susceptibility of magnetically levitating substances

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, Y [Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Tanimoto, Y [Faculty of Pharmacy, Osaka Ohtani University, Nishikiorikita, Tondabayashi 584-8540 (Japan)], E-mail: fuji0710@sci.hiroshima-u.ac.jp

    2009-03-01

    On magnetic force evaluation necessary for magnetically levitated diamagnetic substances, isotropic diamagnetic susceptibility estimation by the ab initio quantum chemical calculation using Gaussian03W was verified for more than 300 molecules in a viewpoint of the accuracy in the absolute value and the calculation level affording good cost performance. From comparison, the method of B3PW91 / 6-311+G(d,p) was found to give the adequate absolute value by the relation of (observed) = (1.03 {+-} 0.005) x (calculated) - (1.22 {+-} 0.60) x 10{sup -6} in a unit of cm{sup 3} mol{sup -1} and good cost performance.

  6. Strongly magnetic soil developed on a non-magnetic rock basement: A case study from NW Bulgaria

    Czech Academy of Sciences Publication Activity Database

    Grison, Hana; Petrovský, Eduard; Jordanova, N.; Kapička, Aleš

    2011-01-01

    Roč. 55, č. 4 (2011), s. 697-716 ISSN 0039-3169 R&D Projects: GA AV ČR(CZ) KJB300120604 Institutional research plan: CEZ:AV0Z30120515 Keywords : magnetic susceptibility * magnetite * soil * pollution * climate * limestone Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.700, year: 2011

  7. Paleomagnetism and Anisotropy of Magnetic Susceptibility study of the Miocene Jack Springs Tuff (Nevada, USA)

    Science.gov (United States)

    Shields, S.; Petronis, M. S.; Pluhar, C. J.; Gordon, L.

    2014-12-01

    The mid-Miocene Jack Springs Tuff (JST) outcrops across the western Mina Deflection accommodation zone, west-central Nevada and into eastern California. Previously, the source location for the JST was unknown, yet recent studies northwest of Mono Lake, CA have identified a relatively un-rotated structural block in which to reference the paleomagnetic data. Although new studies have indicated that this block may be rotated up to 13º, we argue that the probable source area is located near the Bodie Hills, CA. At this site, the paleomagnetic reference direction is D = 353°, I = 43°, α95 = 7.7° (Carlson et al, 2013). Based on these data, the JST can be used to measure absolute vertical-axis rotation as well as enable reconstruction of the paleo-topography using the corrected anisotropy of magnetic susceptibility (AMS) data. A total of 19 sites were sampled to constrain Cenozoic to recent vertical axis rotation within the region and AMS experiments were conducted to determine the flow direction of the JST. Curie point estimates indicate that the JST ranges in titanium concentration from 0.042 to 1.10, indicating a low to moderate titanomagnetite phase (Akimoto, 1962). Demagnetization experiments reveal mean destructive fields of the NRM ranging between 15mT and 40mT suggesting that both multi-domain to pseudo-single domain grains are the dominant ferromagnetic phases that carry the remanence and AMS fabric. Preliminary paleomagnetic data yield stable single component demagnetization behavior for most sites that, after structural correction, indicate clockwise vertical axis rotation ranging from +20°± 10° to +60°± 11° between multiple fault blocks. The uncorrected AMS data yield oblate magnetic fabrics that can be used to infer the transport direction, source region, and paleovalley geometry of the JST. These data are tentatively interpreted to indicate west to east transport of the JST across the Mono Basin region into the Mina Deflection that was erupted and

  8. Estimation of Soil Erosion by Using Magnetic Method: A Case Study of an Agricultural Field in Southern Moravia (Czech Republic)

    Science.gov (United States)

    Petrovsky, E.; Grison, H.; Kapicka, A.; Dlouha, S.; Kodesova, R.; Jaksik, O.

    2013-05-01

    In this study we have applied magnetism of soils for estimation of erosion at an agricultural land. The testing site is situated in loess region in Southern Moravia (in Central Europe). The approach is based on well-established method of differentiation of magnetic parameters of the topsoil and the subsoil horizons as a result of in situ formation of strongly magnetic iron oxides. Our founding is established on a simple tillage homogenization model described by Royall (2001) using magnetic susceptibility and its frequency dependence to estimate soil loss caused by the tillage and subsequent erosion. The original dominant Soil Unit in the investigated area is Haplic Chernozem, which is due to intensive erosion progressively transformed into different Soil Units. The site is characterized by a flat upper part while the middle part, formed by a substantive side valley, is steeper (up to 15°). The side valley represents a major line of concentrated runoff emptying into a colluvial fan. Field measurements of the topsoil volume magnetic susceptibility were carried out by the Bartington MS2D probe. Data are resulting in regular grid of 101 data points, where the bulk soil material was gathered for further laboratory investigations. Moreover, vertical distribution of magnetic susceptibility (deep to 40 cm) was measured on selected transects using the SM400 kappameter. In the laboratory, after drying and sieving of collected soil samples, mass-specific magnetic susceptibility and its frequency-dependent susceptibility was measured. In order to identify magnetic minerals the thermomagnetic analyses were performed using the AGICO KLY-4S Kappabridge with CS-3 furnace. Hysteresis loops were carried out on vibrating magnetometer ADE EV9 to assess the grain-size distribution of ferrimagnetic particles. Hereafter, the isothermal remanent magnetization acqusition followed by D.C. demagnetization were done. All these laboratory magnetic measurements were performed in order to

  9. 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 (Pjcentral 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 center. K1 (maximum) axes are mainly gently plunging (tendency to preferring

  10. Finite-size behaviour of generalized susceptibilities in the whole phase plane of the Potts model

    Science.gov (United States)

    Pan, Xue; Zhang, Yanhua; Chen, Lizhu; Xu, Mingmei; Wu, Yuanfang

    2018-01-01

    We study the sign distribution of generalized magnetic susceptibilities in the temperature-external magnetic field plane using the three-dimensional three-state Potts model. We find that the sign of odd-order susceptibility is opposite in the symmetric (disorder) and broken (order) phases, but that of the even-order one remains positive when it is far away from the phase boundary. When the critical point is approached from the crossover side, negative fourth-order magnetic susceptibility is observable. It is also demonstrated that non-monotonic behavior occurs in the temperature dependence of the generalized susceptibilities of the energy. The finite-size scaling behavior of the specific heat in this model is mainly controlled by the critical exponent of the magnetic susceptibility in the three-dimensional Ising universality class. Supported by Fund Project of National Natural Science Foundation of China (11647093, 11405088, 11521064), Fund Project of Sichuan Provincial Department of Education (16ZB0339), Fund Project of Chengdu Technological University (2016RC004) and the Major State Basic Research Development Program of China (2014CB845402)

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

    Science.gov (United States)

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

    2011-01-01

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

  12. Neutron Diffraction Studies of Nuclear Magnetic Ordering in Copper

    DEFF Research Database (Denmark)

    Jyrkkiö, T.A.; Huiku, M.T.; Siemensmeyer, K.

    1989-01-01

    for measurements in the ordered state; both our calculations and the experiments yield 1 nW beam heating. Polarized neutron experiments show that the scattered intensities from the strong fcc reflections are severely reduced by extinction. This makes the sample not very suitable for further studies with polarized...... to depend strongly on the external magnetic field between zero and the critical fieldB c=0.25 mT, indicating the existence of at least two antiferromagnetic phases. The results are compared to previous measurements of the magnetic susceptibility. Theoretical calculations do not provide a full explanation...

  13. Hydrostatic Pressure Study on 3-K Phase Superconductivity in Sr2RuO4-Ru Eutectic Crystals by AC Magnetic Susceptibility Measurements

    International Nuclear Information System (INIS)

    Yaguchi, Hiroshi; Watanabe, Hiromichi; Sakaue, Akira

    2012-01-01

    We have investigated the effect of hydrostatic pressure on 3-K phase superconductivity in Sr 2 RuO 4 -Ru eutectic crystals by means of AC magnetic susceptibility measurements. We have found that the application of hydrostatic pressure suppresses the superconducting transition temperature T c of the 3-K phase with a pressure coefficient of dT c /dP ≈ −0.2 K/GPa, similar to the case of the 1.5-K phase. We have also observed that the effect of hydrostatic pressure on the 3-K phase seems to be elastic whilst that of uniaxial pressure is plastic.

  14. Theoretical study of in-plane response of magnetic field sensor to magnetic beads in an in-plane homogeneous field

    DEFF Research Database (Denmark)

    Damsgaard, Christian Danvad; Hansen, Mikkel Fougt

    2008-01-01

    We present a systematic theoretical study of the average in-plane magnetic field on square and rectangular magnetic field sensors from a single magnetic bead and a monolayer of magnetic beads magnetized by an in-plane externally applied homogeneous magnetic field. General theoretical expressions...... are derived such that the sensor response and its dependence on the sensor size, spacer layer thickness, bead diameter, and bead susceptibility can easily be evaluated. The average magnetic field from a single bead close to the sensor shows a strong dependence on the position of the bead and a change of sign...... when the bead passes the edge of the sensor in the direction of the applied field. Analytical approximations are derived for the average field from a homogeneous monolayer of beads for beads much smaller than the sensor dimension and for a bead size chosen to minimize the position sensitivity...

  15. Harmonic and static susceptibilities of YBa2Cu3O7

    International Nuclear Information System (INIS)

    Ishida, T.; Goldfarb, R.B.; Okayasu, S.; Kazumata, Y.; Franz, J.; Arndt, T.; Schauer, W.

    1993-01-01

    Intergranular properties of the sintered superconductor YBa 2 Cu 3 O 7 have been studied in terms of complex harmonic magnetic susceptibility χ n χ n ' - iχ n '' (n integer) as well as DC susceptibility χ dc . As functions of temperature T, χ 1 ' and χ 1 '' depend on both the AC magnetic-field amplitude H ac and the magnitude of a superimposed DC field H dc . Only odd-harmonic susceptibilities are observed below the critical temperature, T c , for zero H dc while both odd and even harmonics are observed for nonzero H dc . With T constant, odd-harmonic susceptibilities are even functions of H dc , whereas even-harmonic susceptibilities are odd functions of H dc . Experimental intergranular characteristics of χ n ' and χ n '' are in good agreement with theoretical predictions from a simplified Kim model of magnetization. In contrast, even-harmonic susceptibilities measured for a GdBa 2 Cu 3 O 7 thin film and an YBa 2 Cu 3 O 7 single crystal are not prominent due to missing weak links, whereas odd-harmonic susceptibilities are remarkable. A survey of several models for the harmonic response of superconductors is presented. The DC susceptibility curve for the zero-field-cooled YBa 2 Cu 3 O 7 sample, χ ZFC (T), has a two-step structure arising from intra- and inter-granular components, similar to χ 1 '. DC susceptibility measured upon warming, χ FCW (T), shows a negative peak near T c for the sample cooled rapidly in small DC fields. DC susceptibility measured upon cooling, χ FCC (T), does not show a peak. A negative peak is not seen in measurements on a powdered sample. The negative peak can be explained by intergranular flux depinning upon warming. (orig.)

  16. 87Sr/86Sr dating and preliminary interpretation of magnetic susceptibility logs of giant piston cores from the Rio Grande Rise in the South Atlantic

    Science.gov (United States)

    Lacasse, Christian Michel; Santos, Roberto Ventura; Dantas, Elton Luiz; Vigneron, Quentin; de Sousa, Isabela Moreno Cordeiro; Harlamov, Vadim; Lisniowski, Maria Aline; Pessanha, Ivo Bruno Machado; Frazão, Eugênio Pires; Cavalcanti, José Adilson Dias

    2017-12-01

    Giant piston cores recovered from shallow depths (optimized matching with an internationally recognized timescale of 87Sr/86Sr seawater variation through geological times. Depth-to-age conversion of the magnetic susceptibility logs was implemented based on the identification of correlative peaks between cores and the developed 87Sr/86Sr age model. The influence of Northern Hemisphere glaciation is reflected in these new stratigraphic logs by a gradual increase from ∼2.7 Ma in the lower signal of magnetic susceptibility (below background level), to values approaching the arithmetic means, likely reflecting an overall increase in terrigenous input. The Rio Grande Rise cores have very low Plio-Pleistocene sedimentation rates (∼0.4-0.8 cm/ka), similar to gravity cores from the oligotrophic subtropical South Atlantic (below ∼2000 mbsl), and for which an inverse correlation between carbonate content and magnetic susceptibility was established. The coring depths on the Rio Grande Rise encompass strong gradients in oxygen concentration and other seawater parameters that define today's AAIW/UCDW transition. Depth-dependent variation in sedimentation rates since the onset of Northern Hemisphere glaciation coincides with the incursion of intermediate waters (UCDW, AAIW) in response to the overall reduction of NADW export to the Southern Ocean. Background levels of magnetic susceptibility in the cores suggest that this variation is mainly attributed to terrigenous input. The source region of this material has yet to be traced by considering in particular the mineral composition and paramagnetic properties of the detrital clays.

  17. Gamma-ray spectrometry, electrical resistivity, and magnetic susceptibility of agricultural soils in the Northwest region of the Parana State, Brazil; Gamaespectrometria, resistividade eletrica e susceptibilidade magnetica de solos agricolas no noroeste do estado do Parana

    Energy Technology Data Exchange (ETDEWEB)

    Becegato, Valter Antonio [Universidade do Estado de Santa Catarina-UDESC, Centro de Ciencias Agroveterinarias, Lages, SC (Brazil); Ferreira, Francisco Jose Fonseca, E-mail: becegato@cav.udesc.br, E-mail: francisco.ferreira@ufpr.br [Universidade Federal do Parana (LPGA/UFPR), Curitiba, PR (Brazil). Dept. de Geologia. Lab. de Pesquisas em Geofisica Aplicada

    2005-10-15

    Gamma-ray spectrometry, electrical resistivity, and magnetic susceptibility measurements were taken from agricultural areas near the City of Maringa, in the Northwest region of the Parana state, south Brazil, in order to characterize the spatial distribution of radionuclides (K, eU, and eTh), the apparent resistivity, and the magnetic susceptibility determined for soils. Three different types of soils are present in this agricultural area: Alfisoil, clayey texture Oxisoil, both deriving from Lower Cretaceous basalts of the Serra Geral Formation; and medium texture Oxisoil from reworked Serra Geral and Goio-Ere formations, the latter deriving from sandstones of the Upper Cretaceous Caiua Group. It could be observed that in more clayey soils both concentration of radionuclides and susceptibility values are higher than in more sandy soils, especially due to the higher adsorption in the former and to the higher availability of magnetic minerals in the latter. The average ppm and Bq Kg{sup -1} grades for K, eU, and eTh in the areas under anthropic activity are of 1766-54.75, 0.83-10.22, and 1.78-7.27, respectively. These grades are significantly higher than those of non-occupied or non-fertilized areas (1101-34.15 K, 0.14-1.69 eU, and 1.31-5.36 eTh in ppm and Bq Kg-1, respectively.) Correlations were observed between uranium and clay, uranium and magnetic susceptibility, uranium and organic matter, and between electric resistivity and clay grades. Varied concentrations of radionuclides were also observed in different fertilizer formulations applied to soy and wheat cultures. Apparent electric resistivity values between 25 and 647 Ohm.m and magnetic susceptibility values between 0.28 e 1.10 x 10-3 SI due to clay and magnetic minerals represented important soil discrimination factors in the study area that can be incorporated as easy, low-cost soil mapping tools. (author)

  18. Magnetic susceptibility and spectral gamma logs in the Tithonian-Berriasian pelagic carbonates in the Tatra Mts (Western Carpathians, Poland): Palaeoenvironmental changes at the Jurassic/Cretaceous boundary

    Czech Academy of Sciences Publication Activity Database

    Grabowski, J.; Schnyder, J.; Sobien, K.; Koptíková, Leona; Krzemiński, L.; Pszczółkowski, A.; Hejnar, J.; Schnabl, Petr

    2013-01-01

    Roč. 43, June 2013 (2013), s. 1-17 ISSN 0195-6671 Institutional support: RVO:67985831 Keywords : Berriasian * Gamma-ray spectrometry * magnetic susceptibility * palaeoenvironmental trends * Tithonian Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 2.390, year: 2013

  19. 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.

  20. 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

    Magnetic susceptibility (MS) have been used to characterize soil properties. It gives an indirect information about heavy metals content and degree of human impacts on soil contamination derived from atmospheric pollution (Girault et al., 2011). This method is inexpensive in relation to chemical analysis and very useful to track soil pollution, since several toxic components deposited on soil surface are rich in particulates produced by oxidation processes (Boyko et al., 2004; Morton-Bernea et al., 2009). Thus, identify the spatial distribution of MS is of major importance, since can give an indirect information of high metals content (Dankoub et al., 2012). This allows also to distinguish the pedogenic and technogenic origin magnetic signal. For example Ukraine chernozems contain fine-grained oxidized magnetite and maghemite of pedogenic origin formed by weathering of the parent material (Jeleńska et al., 2004). However, to a correct understanding of variables distribution, the identification of the most accurate interpolation method is fundamental for a better interpretation of map information (Pereira et al., 2013). The objective of this work is to study the spatial variability of soil MS in an agricultural fields located in the Tcherkascy Tishki area (50.11°N, 36.43 °E, 162 m a.s.l), Ukraine. Soil MS was measured in 77 sampling points in a north facing slope. To estimate the best interpolation method, several interpolation methods were tested, as inverse distance to a weight (IDW) with the power of 1,2,3,4 and 5, Local Polynomial (LP) with the power of 1 and 2, Global Polynomial (GP), radial basis functions - spline with tension (SPT), completely regularized spline (CRS), multiquatratic (MTQ), inverse multiquatratic (IMTQ), and thin plate spline (TPS) - and some geostatistical methods as, ordinary kriging (OK), Simple Kriging (SK) and Universal Kriging (UK), used in previous works (Pereira et al., 2014). On average, the soil MS of the studied plot had 686

  1. Effects of tissue susceptibility on brain temperature mapping.

    Science.gov (United States)

    Maudsley, Andrew A; Goryawala, Mohammed Z; Sheriff, Sulaiman

    2017-02-01

    A method for mapping of temperature over a large volume of the brain using volumetric proton MR spectroscopic imaging has been implemented and applied to 150 normal subjects. Magnetic susceptibility-induced frequency shifts in gray- and white-matter regions were measured and included as a correction in the temperature mapping calculation. Additional sources of magnetic susceptibility variations of the individual metabolite resonance frequencies were also observed that reflect the cellular-level organization of the brain metabolites, with the most notable differences being attributed to changes of the N-Acetylaspartate resonance frequency that reflect the intra-axonal distribution and orientation of the white-matter tracts with respect to the applied magnetic field. These metabolite-specific susceptibility effects are also shown to change with age. Results indicate no change of apparent brain temperature with age from 18 to 84 years old, with a trend for increased brain temperature throughout the cerebrum in females relative for males on the order of 0.1°C; slightly increased temperatures in the left hemisphere relative to the right; and a lower temperature of 0.3°C in the cerebellum relative to that of cerebral white-matter. This study presents a novel acquisition method for noninvasive measurement of brain temperature that is of potential value for diagnostic purposes and treatment monitoring, while also demonstrating limitations of the measurement due to the confounding effects of tissue susceptibility variations. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Note: Commercial SQUID magnetometer-compatible NMR probe and its application for studying a quantum magnet.

    Science.gov (United States)

    Vennemann, T; Jeong, M; Yoon, D; Magrez, A; Berger, H; Yang, L; Živković, I; Babkevich, P; Rønnow, H M

    2018-04-01

    We present a compact nuclear magnetic resonance (NMR) probe which is compatible with a magnet of a commercial superconducting quantum interference device magnetometer and demonstrate its application to the study of a quantum magnet. We employ trimmer chip capacitors to construct an NMR tank circuit for low temperature measurements. Using a magnetic insulator MoOPO 4 with S = 1/2 (Mo 5+ ) as an example, we show that the T-dependence of the circuit is weak enough to allow the ligand-ion NMR study of magnetic systems. Our 31 P NMR results are compatible with previous bulk susceptibility and neutron scattering experiments and furthermore reveal unconventional spin dynamics.

  3. Note: Commercial SQUID magnetometer-compatible NMR probe and its application for studying a quantum magnet

    Science.gov (United States)

    Vennemann, T.; Jeong, M.; Yoon, D.; Magrez, A.; Berger, H.; Yang, L.; Živković, I.; Babkevich, P.; Rønnow, H. M.

    2018-04-01

    We present a compact nuclear magnetic resonance (NMR) probe which is compatible with a magnet of a commercial superconducting quantum interference device magnetometer and demonstrate its application to the study of a quantum magnet. We employ trimmer chip capacitors to construct an NMR tank circuit for low temperature measurements. Using a magnetic insulator MoOPO4 with S = 1/2 (Mo5+) as an example, we show that the T-dependence of the circuit is weak enough to allow the ligand-ion NMR study of magnetic systems. Our 31P NMR results are compatible with previous bulk susceptibility and neutron scattering experiments and furthermore reveal unconventional spin dynamics.

  4. Low-field susceptibilities of rare earth spin glass alloys

    International Nuclear Information System (INIS)

    Sarkissian, B.V.B.

    1977-01-01

    Static susceptibility in various applied fields and AC susceptibility data on Sc 13% Gd and Sc 4.5% Tb spin glass alloys are reported. The data show that the sharp peak at the freezing temperature, Tsub(g), normally observed in the low-field susceptibility of spin glasses containing 3d magnetic impurities is observed here in the case of Gd, which is an S state solute, but not for Tb. On the contrary, for the Sc-Tb alloy a rather rounded maximum is observed which becomes slightly sharper with increasing applied magnetic fields. (author)

  5. Magnetic properties of checkerboard lattice: a Monte Carlo study

    Science.gov (United States)

    Jabar, A.; Masrour, R.; Hamedoun, M.; Benyoussef, A.

    2017-12-01

    The magnetic properties of ferrimagnetic mixed-spin Ising model in the checkerboard lattice are studied using Monte Carlo simulations. The variation of total magnetization and magnetic susceptibility with the crystal field has been established. We have obtained a transition from an order to a disordered phase in some critical value of the physical variables. The reduced transition temperature is obtained for different exchange interactions. The magnetic hysteresis cycles have been established. The multiples hysteresis cycle in checkerboard lattice are obtained. The multiples hysteresis cycle have been established. The ferrimagnetic mixed-spin Ising model in checkerboard lattice is very interesting from the experimental point of view. The mixed spins system have many technological applications such as in domain opto-electronics, memory, nanomedicine and nano-biological systems. The obtained results show that that crystal field induce long-range spin-spin correlations even bellow the reduced transition temperature.

  6. Technique for magnetic susceptibility determination in the highly doped semiconductors by electron spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Veinger, A. I.; Zabrodskii, A. G.; Tisnek, T. V.; Goloshchapov, S. I.; Semenikhin, P. V. [Ioffe Institute of the Russian Academy of Sciences, St. Petersburg (Russian Federation)

    2014-08-20

    A method for determining the magnetic susceptibility in the highly doped semiconductors is considered. It is suitable for the semiconductors near the metal - insulator transition when the conductivity changes very quickly with the temperature and the resonance line form distorts. A procedure that is based on double integration of the positive part of the derivative of the absorption line having a Dyson shape and takes into account the depth of the skin layer is described. Analysis is made for the example of arsenic-doped germanium samples at a rather high concentration corresponding to the insulator-metal phase transition.

  7. Geochemical normalization of magnetic susceptibility – a simple tool for distinction the sediment provenance and post-depositional processes in floodplain sediments

    Czech Academy of Sciences Publication Activity Database

    Faměra, Martin; Matys Grygar, Tomáš; Elznicová, J.

    2017-01-01

    Roč. 19, APR (2017) ISSN 1607-7962. [EGU General Assembly 2017. 23.04.2017-28.04.2017, Vienna] Institutional support: RVO:61388980 Keywords : Magnetic susceptibility Subject RIV: DD - Geochemistry http://meetingorganizer.copernicus.org/EGU2017/EGU2017-2797.pdf

  8. Scaling of the susceptibility vs. magnetic-field sweep rate in Fe8 molecular magnet

    Science.gov (United States)

    Jordi, M.; Hernandez-Mínguez, A.; Hernandez, J. M.; Tejada, J.; Stroobants, S.; Vanacken, J.; Moshchalkov, V. V.

    2004-12-01

    The dependence of the magnetization reversal on the sweep rate of the applied magnetic field has been studied for single crystals of Fe8 magnetic molecules. Our experiments have been conducted at temperatures below 1 K and sweep rates of the magnetic field between 103 T/s to 104 T/s. The systematic shift of the values of the magnetic field at which the magnetization reversal occurs, indicates that this reversal process is not governed by the Landau-Zener transition model. Our data can be explained in terms of the superradiance emission model proposed by Chudnovsky and Garanin (Phys. Rev. Lett. 89 (2002) 157201).

  9. Zn induced in-gap electronic states in La214 probed by uniform magnetic susceptibility: relevance to the suppression of superconducting T c

    Science.gov (United States)

    Islam, R. S.; Naqib, S. H.

    2018-02-01

    Substitution of isovalent non-magnetic defects, such as Zn, in the CuO2 plane strongly modifies the magnetic properties of strongly electron correlated hole doped cuprate superconductors. The reason for enhanced uniform magnetic susceptibility, χ, in Zn substituted cuprates is debatable. Generally the defect induced magnetic behavior has been analyzed mainly in terms of two somewhat contrasting scenarios. The first one is due to independent localized moments appearing in the vicinity of Zn arising because of the strong electronic/magnetic correlations present in the host compound and the second one is due to transfer of quasiparticle (QP) spectral weight and creation of weakly localized low-energy electronic states associated with each Zn atom in place of an in-plane Cu. If the second scenario is correct, one should expect a direct correspondence between Zn induced suppression of the superconducting transition temperature, T c, and the extent of the enhanced magnetic susceptibility at low temperature. In this case, the low-T enhancement of χ would be due to weakly localized QP states at low energy and these electronic states will be precluded from taking part in Cooper pairing. We explore this second possibility by analyzing the χ(T) data for La2-x Sr x Cu1-y Zn y O4 with different hole contents, p (=x), and Zn concentrations (y) in this paper. The results of our analysis support this scenario.

  10. Quantitative Susceptibility Mapping in Parkinson's Disease.

    Science.gov (United States)

    Langkammer, Christian; Pirpamer, Lukas; Seiler, Stephan; Deistung, Andreas; Schweser, Ferdinand; Franthal, Sebastian; Homayoon, Nina; Katschnig-Winter, Petra; Koegl-Wallner, Mariella; Pendl, Tamara; Stoegerer, Eva Maria; Wenzel, Karoline; Fazekas, Franz; Ropele, Stefan; Reichenbach, Jürgen Rainer; Schmidt, Reinhold; Schwingenschuh, Petra

    2016-01-01

    Quantitative susceptibility mapping (QSM) and R2* relaxation rate mapping have demonstrated increased iron deposition in the substantia nigra of patients with idiopathic Parkinson's disease (PD). However, the findings in other subcortical deep gray matter nuclei are converse and the sensitivity of QSM and R2* for morphological changes and their relation to clinical measures of disease severity has so far been investigated only sparsely. The local ethics committee approved this study and all subjects gave written informed consent. 66 patients with idiopathic Parkinson's disease and 58 control subjects underwent quantitative MRI at 3T. Susceptibility and R2* maps were reconstructed from a spoiled multi-echo 3D gradient echo sequence. Mean susceptibilities and R2* rates were measured in subcortical deep gray matter nuclei and compared between patients with PD and controls as well as related to clinical variables. Compared to control subjects, patients with PD had increased R2* values in the substantia nigra. QSM also showed higher susceptibilities in patients with PD in substantia nigra, in the nucleus ruber, thalamus, and globus pallidus. Magnetic susceptibility of several of these structures was correlated with the levodopa-equivalent daily dose (LEDD) and clinical markers of motor and non-motor disease severity (total MDS-UPDRS, MDS-UPDRS-I and II). Disease severity as assessed by the Hoehn & Yahr scale was correlated with magnetic susceptibility in the substantia nigra. The established finding of higher R2* rates in the substantia nigra was extended by QSM showing superior sensitivity for PD-related tissue changes in nigrostriatal dopaminergic pathways. QSM additionally reflected the levodopa-dosage and disease severity. These results suggest a more widespread pathologic involvement and QSM as a novel means for its investigation, more sensitive than current MRI techniques.

  11. Rock Magnetic Study of IODP/ICDP Expedition 364 Site M0077A Drill Cores: Post-Impact Sediments, Impact Breccias, Melt, Granitic Basement and Dikes

    Science.gov (United States)

    Fucugauchi, J. U.; Perez-Cruz, L. L.; Rebolledo-Vieyra, M.; Tikoo, S.; Zylberman, W.; Lofi, J.

    2017-12-01

    Drilling at Site M0077 sampled post-impact sediments overlying a peak ring consisting of impact breccias, melt rock and granitoids. Here we focus on characterizing the peak ring using magnetic properties, which vary widely and depend on mineralogy, depositional and emplacement conditions and secondary alterations. Rock magnetic properties are integrated with Multi-Sensor Core Logger (MSCL) data, vertical seismic profile, physical properties, petrographic and chemical analyses and geophysical models. We measure low-field magnetic susceptibility at low- and high-frequencies, intensity and direction of natural remanent magnetization (NRM) and laboratory-induced isothermal (IRM) and anhysteretic (ARM) magnetizations, alternating-field demagnetization of NRM, IRM and NRM, susceptibility variation with temperature, anisotropy of magnetic susceptibility, hysteresis and IRM back-field demagnetization. Post-impact carbonates show low susceptibilities and NRM intensities, variable frequency-dependent susceptibilities and multivectorial remanences residing in low and high coercivity minerals. Hysteresis loops show low coercivity saturation magnetizations and variable paramagnetic mineral contents. Impact breccias (suevites) and melt rock show higher susceptibilities, low frequency-dependent susceptibilities, high NRM, ARM and IRM intensities and moderate ARM intensity/susceptibility ratios. Magnetic signal is dominated by fine-grained magnetite and titanomagnetites with PSD domain states. Melt rocks at the base of impactite section show the highest susceptibilities and remanence intensities. Basement section is characterized by low susceptibilities in the granites and higher values in the dikes, with NRM and ARM intensities increasing towards the base. The high susceptibilities and remanence intensities correlate with high seismic velocities, density and decreased porosity and electrical resistivity. Fracturing and alteration account for the reduced seismic velocities

  12. Magnetic evidence for heavy metal pollution of topsoil in Shanghai, China

    Science.gov (United States)

    Wang, Guan; Liu, Yuan; Chen, Jiao; Ren, Feifan; Chen, Yuying; Ye, Fangzhou; Zhang, Weiguo

    2018-03-01

    This study presents the results obtained from magnetic susceptibility and heavy metal (Cu, Zn, Pb, and Cr) concentration measurements of soil profiles collected from arable land and urban parks in Baoshan District, an industrial district of Shanghai, China. The study focuses on the investigation of vertical variations in magnetic susceptibilities and heavy metal concentrations and on correlations between magnetic susceptibilities and heavy metal concentrations in soil profiles. The results demonstrate that magnetic enhancement in the surface layer of the soil profile is associated with increased heavy metal pollution. The enrichment factors (EF) and the Tomlinson Pollution Load Index (PLI-EF) are calculated for estimating the level of heavy metal pollution of soil profiles in the study. The significant positive correlations between heavy metal contents, enrichment factors (EF), Tomlinson pollution load index (PLI-CF), modified Tomlinson pollution load index (PLI-EF), and magnetic susceptibility (c) indicate that much of the heavy metal contamination in the study area is linked to combustion derived particulate emissions. The results confirm that the combined magnetic measurement and heavy metal concentration analysis could provide useful information for soil monitoring in urban environments. However, the use of magnetic technique to locate the heavy metal pollution boundary in the soil profile of this studied area should be confirmed by further geochemical analysis.

  13. 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. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  14. A kinetic model that explains the dependence of magnetic susceptibility of sediment on grain size and organic matter content in transitional marine environments. Testing case studies in estuarine-like environments of NW Iberia

    Science.gov (United States)

    Rey, D.; Mohamed, K. J.; Andrade, A.; Rubio, B.; Bernabeu, A. M.

    2017-12-01

    The wide use of magnetic proxies to study pollution, sedimentological processes, and environmental and paleoclimatic changes is currently limited by the lack of transference functions that closely correlate with the unmeasurable variables. Among them, magnetic susceptibility (MS) is the oldest and most popular, but have yet to live up to its expectations. This paper explores and quantifies how MS values of surficial sediments in transitional environments depends on grain size and on what can be said about the spatial distribution of hydrodynamic forces and the potential modulation of MS by sediment and organic matter provenances. The concentration of (oxyhydr)oxides in sands (d50 > 63 microns) is primarily controlled by their degree of dilution in the diamagnetic framework, which is larger for coarser grainsizes. In contrast, the concentration of (oxyhydr)oxides in muddy sediments is controlled by their dissolution rate during very early diagenesis, which is controlled by their content in organic matter (TOC), inversely dependent of grainsize. The balance between both components results in the study area in sands of d50 = 68 microns displaying the maximum MS values. The influence of organic matter on the dissolution of magnetite in surficial sediments can be quantified using a simple kinetic model. The model reveals the existence of a negative exponential relationship between magnetic susceptibility and grain size, that depends on the TOC of the fine-grained fraction. The model accurately predicts that a TOC increase of 0.35% results in a 50% reduction in the concentration of magnetite in the sediments of the Ría the Muros. We have also encountered this relationship not universal in this form, as its quantification is strongly modulated by coarse sediment mineralogy, TOC lability and by other factors such as wave climate, depth, and sediment oxygenation. Better understanding and quantification of the role that TOC, hydrodynamics, and changes in the geochemical

  15. Observation of unusual critical region behavior in the magnetic susceptibility of EuSe

    Science.gov (United States)

    Bykovetz, N.; Klein, J.; Lin, C. L.

    2018-05-01

    The Europium Chalcogenides (EuCh: EuO, EuS, EuSe, and EuTe) have been regarded as model examples of simple, cubic, Heisenberg exchange coupled magnetic systems, with a ferromagnetic nearest-neighbor exchange constant J1 and an antiferromagnetic next-nearest-neighbor constant J2. Unlike the other EuCh, EuSe exhibits a range of complex magnetic behaviors, the latter being attributed to EuSe being near the point where J2=-J1, where its magnetism appears to consist of nearly de-coupled 2D ferromagnetic sheets. Analysis of precision SQUID measurements of the magnetic susceptibility χ in EuSe showed that in the region from ˜Tc to ˜2Tc, a fit of the data to the critical equation χ = χ2Tc(T/Tc-1)-γ gives γ=2.0, an exponent not predicted by any current theory. Additionally, this fit predicts that Tc should be ˜0K. We tentatively interpret this by saying that in the paramagnetic region the system "thinks" EuSe should not order above T=0. Tc=0K is predicted by the Mermin-Wagner theorem (MW) for Heisenberg-coupled 2D magnetic systems, and we can show that when J2=-J1, MW can also be applied to the J1, J2 exchange model of the EuCh to give a rigorous Tc=0 prediction. Under 10 kbar applied pressure EuSe exhibits a different γ and fitted Tc. An additional, and rather strange, critical-region effect was discovered. The EuSe sample was found to exhibit a relaxation effect in a small range of temperatures, just above and just below the actual Tc of 4.7K, with time constants of up to 5 minutes. We cannot yet fully explain this observed macroscopic effect.

  16. Magnetic interactions in iron (III) porphyrin chlorides

    International Nuclear Information System (INIS)

    Ernst, J.; Subramanian, Japyesan; Fuhrhop, J.H.

    1977-01-01

    Intermolecular exchange interactions in iron(III) porphyrin chlorides (porphyrin = OEP, proto, TPP) have been studied by X-ray structure, EPR and magnetic susceptibility studies. The crystal structure of Fe(III)OEP-Cl was found to be different from that of the other two. Different types of exchange broadened EPR-spectra are obtained which are attributable to the arrangement in the crystals. The EPR results correlate well with magnetic susceptibility data. (orig.) [de

  17. Critical behavior of AC antiferromagnetic and ferromagnetic susceptibilities of a spin-1/2 metamagnetic Ising system

    International Nuclear Information System (INIS)

    Gulpinar, Gul; Vatansever, Erol

    2012-01-01

    In this study, the temperature variations of the equilibrium and the non-equilibrium antiferromagnetic and ferromagnetic susceptibilities of a metamagnetic system are examined near the critical point. The kinetic equations describing the time dependencies of the total and staggered magnetizations are derived by utilizing linear response theory. In order to obtain dynamic magnetic relaxation behavior of the system, the stationary solutions of the kinetic equations in existence of sinusoidal staggered and physical external magnetic fields are performed. In addition, the static and dynamical mean field critical exponents are calculated in order to formulate the critical behavior of antiferromagnetic and ferromagnetic magnetic response of a metamagnetic system. Finally, a comparison of the findings of this study with previous theoretical and experimental studies is represented and it is shown that a good agreement is found with our results. - Highlights: ► Staggered dynamic susceptibility diverges as T→T N in the low frequency region. ► Dynamic total susceptibility exhibits a finite jump discontinuity as T→T N while wτ 2 ⪡1. ► The slope of the staggered magnetic dispersion curve chances in sign as T→T N .

  18. Study of amorphous semiconductors doped with rare earths (Gd and Er) and conducting polymers by EPR techniques and magnetic susceptibility; Estudo de semicondutores amorfos dopados com terras raras (Gd e Er) e de polimeros condutores atraves das tecnicas de RPE e susceptibilidade magnetica

    Energy Technology Data Exchange (ETDEWEB)

    Sercheli, Mauricio da Silva

    1999-07-01

    This thesis involves the study of amorphous semiconductors and conducting polymers, which have been characterized by EPR and magnetic susceptibility measurements, and to a lesser extent by Raman spectroscopy and RBS. The semiconductors were studied using thin films of silicon doped with rare earth metals, e.g. erbium and gadolinium, which had their magnetic properties studied. Using these studies we could determine the state of valence of the rare earths as well as their concentrations in the silicon matrix. According to our results, the valence of the rare earth metal ions is 3+, and we were able to conclude that 4f electronic shells could not be used for the calculation of the conducting band in this system. Furthermore, the analysis of the data on the magnetic susceptibility of the Er{sup 3+} ion with cubic crystalline acting field, gave us the opportunity to estimate the overall splitting of their electronic states for the first time. The conducting polymers were studied using samples of poly(3-methylthiophene) doped with ClO{sub 4}{sup -}, which show a phase transition in the range of 230 K to 130 K. The electron paramagnetic resonance also gives important information on the crystallization, doping level and the presence of polarons or bipolarons in conducting polymers. (author)

  19. Paramagnetic resonance and susceptibility of ilmenite, FeTiO3 crystal

    Science.gov (United States)

    Mcdonald, P. F.; Parasiris, A.; Pandey, R. K.; Gries, B. L.; Kirk, W. P.

    1991-01-01

    Large high-purity single crystals of FeTiO3 with ilmenite structure have been grown from a stoichiometric melt of Fe2O3 and TiO2 under an inert atmosphere using the modified Czochralski technique. Susceptibility and X-band paramagnetic resonance studies have been performed. Susceptibility measurements indicate a Neel temperature of about 59 K. The paramagnetic resonance spectrum for magnetic field perpendicular to the crystal c axis consists of a portion of a single, very intense approximately Lorentzian absorption line with its peak at about 600 G and half width at half maximum almost 1200 G. The absorption extends to zero magnetic field. For magnetic field approximately parallel to the c axis, the paramagnetic absorption is much smaller and may be considered a superposition of two approximately Lorentzian line shapes. The magnetic resonance measurements indicate a weak temperature dependence and large angular anisotropy.

  20. Magnetic properties in kagomé lattice with RKKY interaction: A Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Masrour, R., E-mail: rachidmasrour@hotmail.com [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, 63, 46000 Safi (Morocco); Laboratoire de Magnétisme et Physique des Hautes Energies L.M.P.H.E.URAC 12, Université Mohammed V, Faculté des Sciences, B.P. 1014, Rabat (Morocco); Jabar, A. [Laboratoire de Magnétisme et Physique des Hautes Energies L.M.P.H.E.URAC 12, Université Mohammed V, Faculté des Sciences, B.P. 1014, Rabat (Morocco); Benyoussef, A. [Laboratoire de Magnétisme et Physique des Hautes Energies L.M.P.H.E.URAC 12, Université Mohammed V, Faculté des Sciences, B.P. 1014, Rabat (Morocco); Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco); Hamedoun, M. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco)

    2016-03-01

    The magnetic properties of the kagomé lattice have been studied with Ruderman–Kittel–Kasuya–Yosida (RKKY) exchange interactions in a spin-7/2 Ising model using Monte Carlo simulations. The RKKY interaction between the two magnetic layers is considered for different distances. The magnetizations and magnetic susceptibilities of this lattice are given for different triquadratic interactions around each triangular face. The critical temperature is obtained for a fixed size. The magnetic hysteresis cycle of kagomé lattice with RKKY interactions is obtained for different temperatures and for different crystal field with a fixed size of nonmagnetic layer. - Highlights: • We study the RKKY interaction in kagomé lattice using the Monte Carlo simulations. • The transition temperature is obtained for kagomé lattice with RKKY interaction. • The coercive field is obtained for kagomé lattice with RKKY interaction.

  1. Suitable reference tissues for quantitative susceptibility mapping of the brain.

    Science.gov (United States)

    Straub, Sina; Schneider, Till M; Emmerich, Julian; Freitag, Martin T; Ziener, Christian H; Schlemmer, Heinz-Peter; Ladd, Mark E; Laun, Frederik B

    2017-07-01

    Since quantitative susceptibility mapping (QSM) quantifies magnetic susceptibility relative to a reference value, a suitable reference tissue has to be available to compare different subjects and stages of disease. To find such a suitable reference tissue for QSM of the brain, melanoma patients with and without brain metastases were measured. Twelve reference regions were chosen and assessed for stability of susceptibility values with respect to multiple intra-individual and inter-individual measurements, age, and stage of disease. Cerebrospinal fluid (CSF), the internal capsule and one region in the splenium of the corpus callosum are the regions with the smallest standard deviations of the mean susceptibility value. The mean susceptibility is 0.010 ± 0.014 ppm for CSF in the atrium of the lateral ventricles (csf post ), -0.060 ± 0.019 ppm for the posterior limb of the internal capsule (ci2), and -0.008 ± 0.019 ppm for the splenium of the corpus callosum. csf post and ci2 show nearly no dependence on age or stage of disease, whereas some other regions, e.g., the red nucleus, show moderate dependence on age or disease. The internal capsule and CSF appear to be the most suitable reference regions for QSM of the brain in the melanoma patients studied. Both showed virtually no dependence on age or disease and small variations among patients. Magn Reson Med 78:204-214, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  2. Magnetic properties of dendrimer structures with different coordination numbers: A Monte Carlo study

    Science.gov (United States)

    Masrour, R.; Jabar, A.

    2016-11-01

    We investigate the magnetic properties of Cayley trees of large molecules with dendrimer structure using Monte Carlo simulations. The thermal magnetization and magnetic susceptibility of a dendrimer structure are given with different coordination numbers, Z=3, 4, 5 and different generations g=3 and 2. The variation of magnetizations with the exchange interactions and crystal fields have been given of this system. The magnetic hysteresis cycles have been established.

  3. Magnetic phase transitions in Er7Rh3 studied on single crystals

    International Nuclear Information System (INIS)

    Tsutaoka, Takanori; Obata, Keisuke; Cheyvuth, Seng; Koyama, Keiichi

    2014-01-01

    Highlights: • Magnetic and electrical properties of Er 7 Rh 3 were studied on single crystals. • The magnetic phase diagram along the c-axis was constructed. • The field-induced magnetic transitions in Er 7 Rh 3 can be explained by the magnetic structure with two magnetic propagation vectors. • The anomalies of electrical resistivity can also be described by the magnetic structure in Er 7 Rh 3 . - Abstract: Magnetic phase transitions in Er 7 Rh 3 with the Th 7 Fe 3 type hexagonal structure have been studied on single crystals by measuring magnetization, magnetic susceptibility and electrical resistivity. Er 7 Rh 3 possesses antiferromagnetic state below T N = 13 K. In the ordered state, the two successive magnetic transitions at T t1 = 6.2 K and T t2 = 4.5 K were observed. Several field-induced magnetic transitions were also observed along the a- and c-axes below T N ; magnetic field H – temperature T phase diagram along the c-axis was constructed. The field-induced magnetic transitions in Er 7 Rh 3 can be explained by the magnetic structure with two magnetic propagation vectors which were derived by the previous neutron diffraction studies. Electrical resistivity shows humps just below the magnetic transition temperatures, T N and T t1 due to the super-zone gap formation at the Fermi level; these anomalies can also be described by the magnetic structure changes in Er 7 Rh 3

  4. [Quantitative magnetic resonance imaging of brain iron deposition: comparison between quantitative susceptibility mapping and transverse relaxation rate (R2*) mapping].

    Science.gov (United States)

    Guan, Ji-Jing; Feng, Yan-Qiu

    2018-03-20

    To evaluate the accuracy and sensitivity of quantitative susceptibility mapping (QSM) and transverse relaxation rate (R2*) mapping in the measurement of brain iron deposition. Super paramagnetic iron oxide (SPIO) phantoms and mouse models of Parkinson's disease (PD) related to iron deposition in the substantia nigra (SN) underwent 7.0 T magnetic resonance (MR) scans (Bruker, 70/16) with a multi-echo 3D gradient echo sequence, and the acquired data were processed to obtain QSM and R2*. Linear regression analysis was performed for susceptibility and R2* in the SPIO phantoms containing 5 SPIO concentrations (30, 15, 7.5, 3.75 and 1.875 µg/mL) to evaluate the accuracy of QSM and R2* in quantitative iron analysis. The sensitivities of QSM and R2* mapping in quantitative detection of brain iron deposition were assessed using mouse models of PD induced by 1-methyl-4-phenyl-1,2,3,6-tetrahy-dropyridine (MPTP) in comparison with the control mice. In SPIO phantoms, QSM provided a higher accuracy than R2* mapping and their goodness-of-fit coefficients (R 2 ) were 0.98 and 0.89, respectively. In the mouse models of PD and control mice, the susceptibility of the SN was significantly higher in the PD models (5.19∓1.58 vs 2.98∓0.88, n=5; Pbrain iron deposition than R2*, and the susceptibility derived by QSM can be a potentially useful biomarker for studying PD.

  5. 57Fe Moessbauer effect studies of magnetic ordering in Lasub(1-x) Srsub(x)CoO3

    International Nuclear Information System (INIS)

    Bhide, V.G.; Rajoria, D.S.

    1975-01-01

    A detailed investigation of the Lasub(1-x)Srsub(x)CoO 3 system was performed for the entire range of Sr concentrations using X-ray diffraction for structural studies, DTA for phase transition analysis, Moessbauer and magnetic susceptibility studies for magnetic properties, and electrical resistivity and Seebeck coefficient studies for electron transport properties. Among other interesting results, samples with x > 0.125 were found to show ferromagnetic ordering. (A.K.)

  6. Distribution of Heavy-Metal Contamination in Regulated River-Channel Deposits: a Magnetic Susceptibility and Grain-Size Approach; River Morava, Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Famera, M.; Bábek, O.; Matys Grygar, Tomáš; Nováková, Tereza

    2013-01-01

    Roč. 224, č. 5 (2013), 1525-1-1525-18 ISSN 0049-6979 R&D Projects: GA AV ČR IAAX00130801 Institutional support: RVO:61388980 Keywords : Fluvial transport * Fly-ash spherules * Geochemical background * Heavy metals * Lithology * Magnetic susceptibility Subject RIV: DD - Geochemistry Impact factor: 1.685, year: 2013

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

    Energy Technology Data Exchange (ETDEWEB)

    Yulianto, Agus; Astuti, Budi; Amalia, Saptaria Rosa [Physics Department, Faculty of Mathematics and Natural Science, Universitas Negeri Semarang (Indonesia)

    2016-04-19

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

  8. Soil erosion at agricultural land in Moravia loess region estimated by using magnetic properties

    Science.gov (United States)

    Kapicka, Ales; Dlouha, Sarka; Petrovsky, Eduard; Jaksik, Ondrej; Grison, Hana; Kodesova, Radka

    2014-05-01

    A detailed field study on a small test site of agricultural land situated in loess region in Southern Moravia (Czech Republic) and subsequent laboratory analyses have been carried out in order to test the applicability of magnetic methods for the estimation of soil erosion. Chernozem, the original dominant soil unit in the wider area, is nowadays progressively transformed into different soil units along with intensive soil erosion. As a result, an extremely diversified soil cover structure has resulted from the erosion. The site was characterized by a flat upper part while the middle part, formed by a substantive side valley, is steeper (up to 15°). We carried out field measurements of magnetic susceptibility on a regular grid, resulting in 101 data points. The bulk soil material for laboratory investigation was gathered from all the grid points. We found a strong correlation between the volume magnetic susceptibility (field measurement) and mass specific magnetic susceptibility measured in the laboratory (R2 = 0.80). Values of the magnetic susceptibility are spatially distributed depending on the terrain. Higher values were measured in the flat upper part (where the original top horizon remained). The lowest values of magnetic susceptibility were obtained on the steep valley sides. Here the original topsoil was eroded and mixed by tillage with the soil substrate (loess). The soil profile that was unaffected by erosion was investigated in detail. The vertical distribution of magnetic susceptibility along this "virgin" profile was measured in laboratory on the samples from layers along the whole profile with 2-cm spacing. The undisturbed profile shows several soil horizons. Horizons Ac and A show a slight increase in magnetic susceptibility up to a depth of about 70 cm. Horizon A/Ck is characterized by a decrease in susceptibility, and the underlying C horizon (h > 103 cm) has a very low value of magnetic susceptibility. The differences between the values of

  9. Possible origins of the susceptibility contrast in the brain. Presidential award proceedings

    International Nuclear Information System (INIS)

    Fukunaga, Masaki; Li, T.Q.; Lee, J.; Matsuura, Eiji; Gelderen, P.V.; Zwart, J.A. de; Merkle, H.; Duyn, J.H.

    2011-01-01

    The magnetic susceptibility contrast derived from high resolution T 2 *-weighted magnetic resonance (MR) imaging at ultra high field strength has been used to reveal laminar contrast in the gray matter (GM) and fiber bundle-like structure in the white matter (WM) of the human brain. This contrast has been attributed to subtle variations in the magnetic properties of brain tissue, which possibly reflect varying iron and myelin content and haemoglobin in the microvasculature. To investigate the origin of this contrast, MRI data from postmortem brain samples were compared with histological staining for iron and myelin. The laminar susceptibility variations in GM strongly correlate with local iron content, which generally co-localized with myelin. On the other hand, fiber bundles in white matter, shows strong susceptibility contrast in the absence of iron while myelin is high. The results suggest that iron contributes significantly to susceptibility contrast across the cortical GM, but myelin is the dominant source of susceptibility in WM bundles. (author)

  10. Theoretical study of the magnetic exchange interaction in catena-μ-Tris[oxalato(2-)-O1,O2;O3,O4]-dicopper complex with interlocked helical chains

    International Nuclear Information System (INIS)

    Negodaev, Igor; Queralt, Nuria; Caballol, Rosa; Graaf, Coen de

    2011-01-01

    Graphical abstract: From electronic structure calculations on fragments to the magnetic susceptibility after resolving the magnetic topology. Research highlights: → Estimates of magnetic couplings in an extended structure with Cu bridged by oxalato. → Determination of the magnetic structure based on the calculated magnetic couplings. → Calculation of the magnetic susceptibility curve from the local magnetic couplings. - Abstract: The coupling of the spin moments has been studied in an oxalato-based 3D extended structure with Cu(II) ions as magnetic sites. The ab initio calculations reveal that two of the three different magnetic interaction paths are characterized by a strong coupling, while the third one presents weaker interaction. Based on these calculated values, the magnetic topology of the material is determined as an alternating chain with weak interchain coupling. A theoretical estimate of the temperature dependence of the magnetic susceptibility is derived from the diagonalization of the Heisenberg Hamiltonian for a multi-center magnetic model with boundary conditions. The theoretical procedure can serve as guide in an experimental determination of the magnetic coupling parameters in 3D extended structure with oxalato-bridges as found in the hexagonal layers of the bifunctional materials.

  11. Magnetic susceptibility of the rare earth tungsten oxide bronzes of the defected perovskite-type structure (Rsub(x)WO/sub 3/)

    Energy Technology Data Exchange (ETDEWEB)

    Gesicki, A; Polaczek, A [Warsaw Univ. (Poland)

    1975-01-01

    Magnetic susceptibility of rare earth tungsten bronzes Rsub(x)WO/sub 3/ of cubic symmetry was measured in the 80-293 K range with the Gouy method. In disagreement with the data reported by other authors it was stated that the Curie-Weiss law with negative Weiss parameter was fulfilled in each case. Possible coupling mechanisms are briefly discussed.

  12. Elastic oscillation damping and magnetic susceptibility in Y19Fe81 spin glass in the temperature range 70-300 K

    International Nuclear Information System (INIS)

    Zolotukhin, I.V.; Balalaev, S.Yu.

    1990-01-01

    Relaxation properties of Y 19 Fe 81 spin glass (SG) were investigated by means of internal friction(IF). Relaxation process resulting from transition to SG state was determined at sound range frequencies in amorphous alloy. On the basis of the obtained results concerning IF and magnetic susceptibility it follows, that relaxation of certain part of cluster magnetic moments lies within 10 -5 -10 -3 s limits with 0.11±0.06 eV activation energy. IF technique is shown to be used for investigation into relaxation properties, in particular, for acquisition of data on temperature of transition to SG' state

  13. Experimental study of fly-ash migration by using magnetic method

    Czech Academy of Sciences Publication Activity Database

    Kapička, Aleš; Kodešová, R.; Petrovský, Eduard; Hůlka, Z.; Grison, Hana; Kaška, M.

    2011-01-01

    Roč. 55, č. 4 (2011), s. 683-696 ISSN 0039-3169 R&D Projects: GA AV ČR IAA300120701 Grant - others:GA AV ČR(CZ) M100120901 Institutional research plan: CEZ:AV0Z30120515 Keywords : environmental magnetism * fly-ash migration * magnetic susceptibility * SM400 Kappameter Subject RIV: DK - Soil Contamination ; De-contamination incl. Pesticides Impact factor: 0.700, year: 2011

  14. 3D Inversion of Magnetic Data through Wavelet based Regularization Method

    Directory of Open Access Journals (Sweden)

    Maysam Abedi

    2015-06-01

    Full Text Available This study deals with the 3D recovering of magnetic susceptibility model by incorporating the sparsity-based constraints in the inversion algorithm. For this purpose, the area under prospect was divided into a large number of rectangular prisms in a mesh with unknown susceptibilities. Tikhonov cost functions with two sparsity functions were used to recover the smooth parts as well as the sharp boundaries of model parameters. A pre-selected basis namely wavelet can recover the region of smooth behaviour of susceptibility distribution while Haar or finite-difference (FD domains yield a solution with rough boundaries. Therefore, a regularizer function which can benefit from the advantages of both wavelets and Haar/FD operators in representation of the 3D magnetic susceptibility distributionwas chosen as a candidate for modeling magnetic anomalies. The optimum wavelet and parameter β which controls the weight of the two sparsifying operators were also considered. The algorithm assumed that there was no remanent magnetization and observed that magnetometry data represent only induced magnetization effect. The proposed approach is applied to a noise-corrupted synthetic data in order to demonstrate its suitability for 3D inversion of magnetic data. On obtaining satisfactory results, a case study pertaining to the ground based measurement of magnetic anomaly over a porphyry-Cu deposit located in Kerman providence of Iran. Now Chun deposit was presented to be 3D inverted. The low susceptibility in the constructed model coincides with the known location of copper ore mineralization.

  15. Magnetism of soils applied for estimation of erosion at an agricultural land

    Science.gov (United States)

    Kapicka, Ales; Dlouha, Sarka; Grison, Hana; Jaksik, Ondrej; Kodesova, Radka; Petrovsky, Eduard

    2013-04-01

    A detailed field study on small test site of agricultural land situated in loess region in Southern Moravia (Czech Republic), followed by laboratory analyses, has been carried out in order to test the applicability of magnetic methods in soil erosion estimation. The approach is based on the well-established differentiation in magnetic signature of topsoil from subsoil horizons as a result of "in situ" formation of strongly magnetic iron oxides e.g. (Maher 1986). Introducing a simple tillage homogenization model for predicting magnetic signal after uniform mixing of soil material as a result of tillage and subsequent erosion, Royall (2001) showed that magnetic susceptibility and its frequency dependence can be used to estimate soil loss. Haplic Chernozem is an original dominant soil unit in the wider area, nowadays progressively transformed into different soil units along with intensive soil erosion. The site was characterized by a flat upper part while the middle part, formed by a substantive side valley, is steeper (up to 15°). The side valley represented a major line of concentrated runoff emptying into a colluvial fan (Zadorova et al., 2011; Jaksik et al., 2011). Field measurements of magnetic susceptibility were carried out on regular grid, resulting in 101 data points. Bulk soil material for laboratory investigation was gathered from all grid points. Mass specific magnetic susceptibility χ and its frequency dependence kFD was used to estimate the significance of SP ferrimagnetic particles of pedogenic origin. Thermomagnetic analyses, hysteresis measurement and SEM were used in order to determine dominant ferrimagnetic carriers in top-soil and sub-soil layers. Strong correlation was found between the volume magnetic susceptibility (field measurement) and mass specific magnetic susceptibility measured in the laboratory (R2 = 0.80). At the same time, no correlations were found between the values of kFD and mass specific susceptibility. Values of organic carbon

  16. Moessbauer study of the magnetic phase transformations in SnMn3N

    International Nuclear Information System (INIS)

    Nagy, D.L.; Zimmer, G.J.; Lohner, T.; Senateur, J.P.

    1975-01-01

    Moessbauer measurements were performed on SnMn 3 N with the aim of verifying the magnetic phase transformations at 175 and 230 K and the Neel transition at 475 K as well as of seeking an explanation for the anomalous peak in magnetic susceptibility about 380 K. Moessbauer spectra were taken at several temperatures between 83 and 475 K and evaluated by a least square fitting program. Abrupt changes in the hyperfine field were found at 175, 230 and 350 K indicating first-order magnetic phase transformations at these temperatures; the 350 K transformation is certainly related to the anomaly in susceptibility. About 475 only a smooth change in the hyperfine field was found suggesting the Neel transition to be of the second order. An attempt is made to explain the relatively high hyperfine field in the cubic antiferromagnetic phase. (A.K.)

  17. AC susceptibility of thin Pb films in intermediate and mixed state

    Energy Technology Data Exchange (ETDEWEB)

    Janu, Zdenek, E-mail: janu@fzu.cz [Institute of Physics of the AS CR, v.v.i., Na Slovance 2, CZ-182 21 Prague 8 (Czech Republic); Svindrych, Zdenek [Institute of Physics of the AS CR, v.v.i., Na Slovance 2, CZ-182 21 Prague 8 (Czech Republic); Trunecek, Otakar [Charles University in Prague, Faculty of Mathematics and Physics, Ke Karlovu 3, CZ-121 16 Prague 2 (Czech Republic); Kus, Peter; Plecenik, Andrej [Komenius University in Bratislava, Faculty of Mathematics, Physics, and Informatics, Mlynska dolina, 842 48 Bratislava 4 (Slovakia)

    2011-12-15

    Thickness dependent transition in AC susceptibility between intermediate and mixed state in type-I superconducting films. The temperature induced crossover between reversible and irreversible behavior was observed in the thicker film. The temperature dependence of the AC susceptibility in mixed state follows prediction of model based on Bean critical state. The temperature dependence of the harmonics of the complex AC susceptibility in the intermediate state is explained. Thin films of type I superconductors of a thickness comparable or less than a flux penetration length behave like type II superconductors in a mixed state. With decreasing film thickness normal domains carrying a magnetic flux get smaller with smaller number of flux quanta per domain and finally transform into single quantum flux lines, i.e. quantum vortices similar to those found in type II superconductors. We give an evidence of this behavior from the measurements of the nonlinear response of a total magnetic moment to an applied AC magnetic field, directly from the temperature dependence of an AC susceptibility.

  18. 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.

  19. Low Field Magnetic and Thermal Hysteresis in Antiferromagnetic Dysprosium

    Directory of Open Access Journals (Sweden)

    Iuliia Liubimova

    2017-06-01

    Full Text Available Magnetic and thermal hysteresis (difference in magnetic properties on cooling and heating have been studied in polycrystalline Dy (dysprosium between 80 and 250 K using measurements of the reversible Villari effect and alternating current (AC susceptibility. We argue that measurement of the reversible Villari effect in the antiferromagnetic phase is a more sensitive method to detect magnetic hysteresis than the registration of conventional B(H loops. We found that the Villari point, recently reported in the antiferromagnetic phase of Dy at 166 K, controls the essential features of magnetic hysteresis and AC susceptibility on heating from the ferromagnetic state: (i thermal hysteresis in AC susceptibility and in the reversible Villari effect disappears abruptly at the temperature of the Villari point; (ii the imaginary part of AC susceptibility is strongly frequency dependent, but only up to the temperature of the Villari point; (iii the imaginary part of the susceptibility drops sharply also at the Villari point. We attribute these effects observed at the Villari point to the disappearance of the residual ferromagnetic phase. The strong influence of the Villari point on several magnetic properties allows this temperature to be ranked almost as important as the Curie and Néel temperatures in Dy and likely also for other rare earth elements and their alloys.

  20. Structure, magnetism, and theoretical study of a mixed-valence Co(II)3Co(III)4 heptanuclear wheel: lack of SMM behavior despite negative magnetic anisotropy.

    Science.gov (United States)

    Chibotaru, Liviu F; Ungur, Liviu; Aronica, Christophe; Elmoll, Hani; Pilet, Guillaume; Luneau, Dominique

    2008-09-17

    A mixed-valence Co(II)/Co(III) heptanuclear wheel [Co(II)3Co(III)4(L)6(MeO)6] (LH2 = 1,1,1-trifluoro-7-hydroxy-4-methyl-5-aza-hept-3-en-2-one) has been synthesized and its crystal structure determined using single-crystal X-ray diffraction. The valence state of each cobalt ion was established by bond valence sum calculations. Studies of the temperature dependence of the magnetic susceptibility and the field dependence of the magnetization evidence ferromagnetic interactions within the compound. In order to understand the magnetic properties of this Co7 wheel, we performed ab initio calculations for each cobalt fragment at the CASSCF/CASPT2 level, including spin-orbit coupling effects within the SO-RASSI approach. The four Co(III) ions were found to be diamagnetic and to give a significant temperature-independent paramagnetic contribution to the susceptibility. The spin-orbit coupling on the three Co(II) sites leads to separations of approximately 200 cm(-1) between the ground and excited Kramers doublets, placing the Co7 wheel into a weak-exchange limit in which the lowest electronic states are adequately described by the anisotropic exchange interaction between the lowest Kramers doublets on Co(II) sites. Simulation of the exchange interaction was done within the Lines model, keeping the fully ab initio treatment of magnetic anisotropy effects on individual cobalt fragments using a recently developed methodology. A good description of the susceptibility and magnetization was obtained for nearest-neighbor (J1) and next-nearest-neighbor (J2) exchange parameters (1.5 and 5.5 cm(-1), respectively). The strong ferromagnetic interaction between distant cobalt ions arises as a result of low electron-promotion energies in the exchange bridges containing Co(III) ions. The calculations showed a large value of the magnetization along the main magnetic axis (10.1 mu(B)), which is a combined effect of the ferromagnetic exchange interaction and negative magnetic anisotropy on

  1. A phenomenological approach to study the effect of uniaxial anisotropy on the magnetization of ferromagnetic nanoparticles

    Science.gov (United States)

    Sánchez-Marín, N.; Cuchillo, A.; Knobel, M.; Vargas, P.

    2018-04-01

    We study the effect of the uniaxial anisotropy in a system of ideal, noninteracting ferromagnetic nanoparticles by means of a thermodynamical model. We show that the effect of the anisotropy can be easily assimilated in a temperature shift Ta∗, in analogy to what was proposed by Allia et al. (2001) in the case of interacting nanomagnets. The phenomenological anisotropic Ta∗ parameter can be negative, indicating an antiferromagnetic-like behavior, or positive, indicating a ferromagnetic-like character as seen in the inverse susceptibility behavior as a function of temperature. The study is done considering an easy axis distribution to take into account the anisotropy axis dispersion in real samples (texture). In the case of a volumetric uniform distribution of anisotropy axes, the net effect makes Ta∗ to vanish, and the magnetic susceptibility behaves like a conventional superparamagnetic system, whereas in the others a finite value is obtained for Ta∗ . When magnetic moment distribution is considered, the effect is to enhance the Ta∗ parameter, when the dispersion of the magnetic moments becomes wider.

  2. Magnetism and magnetic mineralogy of ash flow tuffs from Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Schlinger, C.M.; Veblen, D.R.; Rosenbaum, J.G.

    1991-01-01

    The magnetic susceptibility χ and remanent magnetization of an ash flow sheet are profoundly influenced by cooling history after emplacement. Maxima and minima in χ measured along profiles at Yucca Mountain, Nevada, identify persistent magnetic marker horizons within vitric portions of the Tiva Canyon and underlying Topopah Spring Members of the Paintbrush Tuff. The observed stratigraphic changes in magnetic properties reflect variations in amounts and mineralogy of Fe-Ti oxide phenocrysts, and the presence, shape, size, and mineralogy of magnetic Fe-oxide microcrystals that precipitated at high temperature after emplacement of each sheet. The size variations of the precipitated Fe-oxides, which were established using transmission electron microscopy (TEM) and petrographic observation, are consistent both with variations in magnetic susceptibility measured at the outcrop and with variations in the intensity of remanent magnetization. Several interpretations of the shape anisotropy of the precipitated Fe-oxide are possible, including growth by a dislocation mechanism. Additionally, the observed elongation of precipitated microcrystals is consistent with theoretical predictions for growth in a uniaxial stress field. Susceptibility variations as established at the outcrop, as well as in the borehole, offer a potentially useful tool for stratigraphic correlation of ash flow sheets

  3. The critical properties of magnetic films

    International Nuclear Information System (INIS)

    Saber, M.; Ainane, A.; Essaoudi, I.; Miguel, J.J. de

    2010-01-01

    Within the framework of the transverse spin-1/2 Ising model and by using the effective field theory with a probability distribution technique that accounts for the self spin correlations, we have studied the critical properties of an L-layer film of simple cubic symmetry in which the exchanges strength are assumed to be different from the bulk values in N S surface layers. We derive and illustrate the expressions for the phase diagrams, order parameter profiles and susceptibility. In such films, the critical temperature can shift to either lower or higher temperature compared with the corresponding bulk value. We calculate also some magnetic properties of the film, such as the layer magnetizations, their averages and their profiles and the longitudinal susceptibility of the film. The film longitudinal susceptibility still diverges at the film critical temperature as does the bulk longitudinal susceptibility.

  4. Utilizing of magnetic parameters for evaluation of soil erosion rates on two different agricultural sites

    Science.gov (United States)

    Kapicka, A.; Grison, H.; Petrovsky, E.; Jaksik, O.; Kodesova, R.

    2015-12-01

    Field measurements of magnetic susceptibility were carried out on regular grid, resulting in 101 data points at Brumovice and 65 at Vidim locality. Mass specific magnetic susceptibility χ and its frequency dependence χFD was used to estimate the significance of SP ferrimagnetic particles of pedogenic origin in topsoil horizons. The lowest magnetic susceptibility was obtained on the steep valley sides. Here the original topsoil was eroded and mixed by tillage with the soil substrate (loess). Soil profiles unaffected by erosion were investigated in detail. The vertical distribution of magnetic susceptibility along these "virgin" profiles was measured in laboratory on samples collected with 2-cm spacing. The differences between the distribution of susceptibility in the undisturbed soil profiles and the magnetic signal after uniform mixing of the soil material as a result of erosion and tillage are fundamental for the estimation of soil loss in the studied test fields. Maximum cumulative soil erosion depth in Brumovice and Vidim is around 100 cm and 50 cm respectively. The magnetic method is suitable for mapping at the chernozem localities and measurement of soil magnetic susceptibility is in this case useful and fast technique for quantitative estimation of soil loss caused by erosion. However, it is less suitable (due to lower magnetic differentiation with depth) in areas with luvisol as dominant soil unit. Acknowledgement: This study was supported by NAZV Agency of the Ministry of Agriculture of the Czech Republic through grant No QJ1230319.

  5. Magnetic properties of Zn(P/sub x/As/sub 1-x/)2 alloys

    International Nuclear Information System (INIS)

    Vitkina, T.Z.; Smolyarenko, E.M.; Trukhan, V.M.

    1987-01-01

    The authors study the magnetic properties of Zn(P/sub x/As/sub 1-x/) 2 alloys. The concentration-dependent magnetic susceptibility of these alloys is shown, as is the temperature dependence of the magnetic susceptibility in solid solutions of the alloys. The diamagnetic susceptibility associated with the valence electrons displays a marked change for a transition to the bound state inasmuch as the valence electrons constitute the chemical bonding in the crystal. The diamagnetic component of the susceptibility of the valence electrons is calculated according to the MO LCAO approximation on the assumption that there is sp 3 -hybridization of the atomic wave function

  6. Magnetic Fabrics and Source Implications of Chisulryoung Ignimbrites, South Korea

    Directory of Open Access Journals (Sweden)

    Hoabin Hong

    2016-08-01

    Full Text Available The anisotropy of magnetic susceptibility (AMS of late Cretaceous ash-flow tuffs in Chisulryoung Volcanic Formation, southeastern Korea was studied to define the primary pyroclastic flow azimuth. AMS data revealed a dominant oblate fabric with a tight clustering of k3 (minimum axis of magnetic susceptibility and shallow dispersal of k1 (maximum axis of magnetic susceptibility and k2 (intermediate axis of magnetic susceptibility. Dominance of oblate fabrics indicates clast imbrications imposed by compaction and welding. Flow azimuth inferred from AMS data indicates the nearby intrusive welded tuff (IWT as the source of calderas for ignimbrites. Such an inference is supported by geologic investigations, in which the IWT displays eutaxitic textures nearly parallel to its subvertical contacts. The results are compatible with a unique prolate fabric and an anomalously high inclination observed for the IWT, possibly produced by rheomorphic flows as the welded tuff is squeezed along the rough-surfaced dyke walls due to agglutination.

  7. Magnetic properties of fishes from rivers near Semarang, Central Java

    Science.gov (United States)

    Khumaedi; Nurbaiti, U.; Setyaningsi, N. E.

    2018-03-01

    Magnetic properties, in the form of magnetic susceptibility (χ) and frequency-dependent susceptibility (χ fd) were measured on scores of samples made of fishes from river nearby Semarang, Central Java. Semarang is one of the major cities in Indonesia, where the river systems are very likely to be contaminated by anthropogenic activities. The objective of this study is to identify the presence of heavy metals in the fishes that will determine the suitability of these fishes for healthy food. The results show that magnetic susceptibility varies from -0.3 to 13.8 × 10-8 m3/kg, while the frequency-dependent susceptibility is less than 3% indicating the predominance of ferromagnetic minerals. Quantitative chemical analyses on four samples show consistently high concentration of Ca, while Fe, Hg, Cu, Pb, Cd, and Ni present a few in some of the samples. This finding shows that the fishes are suitable for the ongoing research on environmental magnetism.

  8. Intrinsic functional brain mapping in reconstructed 4D magnetic susceptibility (χ) data space.

    Science.gov (United States)

    Chen, Zikuan; Calhoun, Vince

    2015-02-15

    By solving an inverse problem of T2*-weighted magnetic resonance imaging for a dynamic fMRI study, we reconstruct a 4D magnetic susceptibility source (χ) data space for intrinsic functional mapping. A 4D phase dataset is calculated from a 4D complex fMRI dataset. The background field and phase wrapping effect are removed by a Laplacian technique. A 3D χ source map is reconstructed from a 3D phase image by a computed inverse MRI (CIMRI) scheme. A 4D χ data space is reconstructed by repeating the 3D χ source reconstruction for each time point. A functional map is calculated by a temporal correlation between voxel signals in the 4D χ space and the timecourse of the task paradigm. With a finger-tapping experiment, we obtain two 3D functional mappings in the 4D magnitude data space and in the reconstructed 4D χ data space. We find that the χ-based functional mapping reveals co-occurrence of bidirectional responses in a 3D activation map that is different from the conventional magnitude-based mapping. The χ-based functional mapping can also be achieved by a 3D deconvolution of a phase activation map. Based on a subject experimental comparison, we show that the 4D χ tomography method could produce a similar χ activation map as obtained by the 3D deconvolution method. By removing the dipole effect and other fMRI technological contaminations, 4D χ tomography provides a 4D χ data space that allows a more direct and truthful functional mapping of a brain activity. Published by Elsevier B.V.

  9. AC susceptibility and NQR measurements on CeCu6 below 5 mK

    International Nuclear Information System (INIS)

    Jin, C.; Lee, D.M.; Pollack, L.; Smith, E.N.; Markert, J.T.; Maple, M.B.; Hinks, D.G.

    1994-01-01

    We have measured the zero field ac magnetic susceptibility of single and polycrystalline CeCu 6 samples down to 100 μK. For the single crystal sample, the susceptibility shows pronounced anisotropic behavior with respect to the crystal orientation. At ∼3 mK the susceptibility along two different crystal orientations shows a broad peak, and at 500 μK the susceptibility shows a second peak along one orientation and a plateau along the other. The susceptibility of the polycrystalline sample has a similar peak at 3 mK. NQR measurements are under way to study the Cu nuclear spin system in this compound in order to gain additional information about the nature of the peaks. (orig.)

  10. The study of magnetic properties and relaxation processes in Co/Au bimetallic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hrubovčák, Pavol [Department of Condensed Matter Physics, P.J. Šafárik University, Park Angelinum 9, Košice (Slovakia); Zeleňáková, Adriana, E-mail: adriana.zelenakova@upjs.sk [Department of Condensed Matter Physics, P.J. Šafárik University, Park Angelinum 9, Košice (Slovakia); Zeleňák, Vladimir [Department of Inorganic Chemistry, P.J. Šafárik University, Moyzesova 11, Košice (Slovakia); Kováč, Jozef [Institute of Experimental Physics, SAS, Watsonova 41, Košice (Slovakia)

    2015-11-15

    Co/Au bimetallic fine nanoparticles were prepared employing the method of microemulsion using reverse micelle as nanoreactor, controlling the particles size. Magnetic and structural properties of two different samples Co/Au1 and Co/Au2 with almost comparable size of Co core and different size of Au layer were studied. The investigation of magnetic relaxation processes present in the particles was carried out by means of ac and dc magnetization data obtained at different temperatures and magnitudes of magnetic field. We observed the existence of superspin glass state characterized by the strong inter-particle interactions in the nanoparticle systems. In this paper, we discuss the attributes of novel superspin glass magnetic state reflected on various features (saturated FC magnetization at low temperatures, shift of the Cole–Cole arc downwards) and calculated parameters (relaxation time, critical exponent zv ∼ 10 and frequency dependent criterion p < 0.05). Comparison of the magnetic properties of two studied samples show that the thickness of diamagnetic Au shell significantly influences the magnetic interactions and change the relaxation dynamics. - Highlights: • Co/Au fine nanoparticles prepared by reverse micelle as nanoreactor, controlling the size. • Existence of superspin glass state confirmed from ac magnetic susceptibility study. • Individual particles exhibit the collective behavior below glass temperature T{sub SSG}. • Influence of diamagnetic shell on the magnetic properties of core–shell nanoparticles.

  11. A comparative study of magnetic properties of MnFe2O4 nanoparticles prepared by thermal decomposition and solvothermal methods

    Directory of Open Access Journals (Sweden)

    B Aslibeiki

    2017-09-01

    Full Text Available A comparative study of magnetic properties of MnFe2O4 ferrite nanoparticles prepared by two different methods has been reported. The first sample (S1 was synthesized by thermal decomposition of metal nitrates. And the second sample (S2 was prepared by solvothermal method using Tri-ethylene glycol (TEG. Magnetic hysteresis loops at 300 and 5 K; magnetization and AC susceptibility measurements versus temperature confirmed the effective role of TEG on the magnetic properties of nanoparticles. The results showed that, at 300 K the saturation magnetization (MS of S2 sample is 46% greater than that of S1 sample. At 5 K, the difference in MS of the samples raised to 60%. AC susceptibility measurements at different frequencies and also magnetization versus temperature under field cooling and zero field cooling processes revealed that, the TEG molecules influence the surface spins order of S2 sample. The sample S1 showed strongly interacting superspin glass state, while the sample S2 consists of weakly interacting superparamagnetic nanoparticles.

  12. Magntic susceptibility as a proxy to heavy metal content in the sediments of Anzali wetland, Iran

    Directory of Open Access Journals (Sweden)

    Naseh Mohammad Reza Vesali

    2012-12-01

    Full Text Available Abstract Heavy metal concentrations and magnetic susceptibility of sediment samples were analyzed as indicators of urban and industrial contamination in Anzali wetland in Gilan, Iran. The aim was to investigate the suitability of magnetic properties measurements for indicating heavy metal pollution. The concentration of six heavy metals (Ni, Cr, Cd, Zn, Fe, and Pb was determined in different depths of four sediment core samples within four different regions of the wetland (Abkenar, Hendekhaleh, Shijan and Siakeshim. Average concentration of heavy metals in the sediment cores was higher than the severe effect level (SEL for Ni, Cr and Fe (77.26, 113.63 ppm and 5.2%, respectively and lower than SEL for Cd, Zn and Pb (0.84, 137.7, 29.77 ppm, respectively. It was found that the trend of metal concentrations with the depth is different in each core and is related to the pollution discharges into the rivers entering the wetland. Core magnetic susceptibility measurements also showed different magnetic properties in each core. Cluster analysis was applied using Pearson correlation coefficient between heavy metal concentrations and magnetic properties across each core. Significant relationship was found to exist between magnetic susceptibility and the concentration of Ni in Abkenar and the concentration of Fe in other regions. Whereas Abkenar is almost the isolated and uncontaminated region of the wetland, it revealed a difference in magnetic properties between contaminated and uncontaminated sediments. It was concluded that magnetic properties of samples from contaminated zone were mostly related to Fe content. The result of this study demonstrated that magnetic susceptibility measurements could be applied as a proxy method for heavy metal pollution determination in marine environments in Iran especially as a rapid and cost-effective introductory site assessments.

  13. Neutron diffraction studies on structural and magnetic properties of RE2NiGe3 (RE=La, Ce)

    International Nuclear Information System (INIS)

    Kalsi, Deepti; Rayaprol, S.; Siruguri, V.; Peter, Sebastian C.

    2014-01-01

    We report the crystallographic properties of RE 2 NiGe 3 (RE=La, Ce) synthesized by arc melting. Rietveld refinement on the powder neutron diffraction (ND) data suggest both compounds are isostructural and crystallize in the non-centrosymmetric Er 2 RhSi 3 type structure having hexagonal space group P6 ¯ 2c. In the crystal structure of RE 2 NiGe 3 , two dimensional arrangements of nickel and germanium atoms lead to the formation of hexagonal layers with rare earth atoms sandwiched between them. Magnetic susceptibility measurements performed in low fields exhibit antiferromagnetic ordering in cerium compound around (T o =) 3.2 K. Neutron diffraction measurements at 2.8 K (i.e., at Tmagnetic order. - Graphical abstract: The compounds La 2 NiGe 3 and Ce 2 NiGe 3 crystallize in the Er 2 RhSi 3 type. Magnetic susceptibility show antiferromagnetic ordering for Ce 2 NiGe 3 at 3.2 K and neutron diffraction confirms the absence of long range ordering. - Highlights: RE 2 NiGe 3 (RE=La, Ce) crystallize in the ordered superstructure of the AlB 2 type. Magnetic susceptibility measurements exhibit antiferromagnetic ordering in Ce 2 NiGe 3 . Structure and magnetism of RE 2 NiGe 3 (RE=La, Ce) are studied by neutron diffraction

  14. RHIC susceptibility to variations in systematic magnetic harmonic errors

    International Nuclear Information System (INIS)

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

    1994-01-01

    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

  15. Development of a nano-tesla magnetic field shielded chamber and highly precise AC-susceptibility measurement coil at μK temperatures

    Science.gov (United States)

    Kumar, Anil; Prakash, Om; Ramakrishanan, S.

    2014-04-01

    A special sample measurement chamber has been developed to perform experiments at ultralow temperatures and ultralow magnetic field. A high permeability material known as cryoperm 10 and Pb is used to shield the measurement space consisting of the signal detecting set-up and the sample. The detecting setup consists of a very sensitive susceptibility coil wound on OFHC Cu bobbin.

  16. Iron-titanium oxide minerals and magnetic susceptibility anomalies in the Mariano Lake-Lake Valley cores - Constraints on conditions of uranium mineralization in the Morrison Formation, San Juan Basin, New Mexico

    International Nuclear Information System (INIS)

    Reynolds, R.L.; Fishman, N.S.; Scott, J.H.; Hudson, M.R.

    1986-01-01

    Petrographic study of the Mariano Lake-Lake Valley cores reveals three distinct zones of postdepositional alteration of detrital Fe-Ti (iron-titanium) oxide minerals in the Westwater Canyon Member of the Upper Jurassic Morrisson Formation. In the uranium-bearing and adjacent portions of the Westwater Canyon, these detrital Fe-Ti oxide minerals have been thoroughly altered by leaching of iron. Stratigraphically lower parts of the Westwater Canyon and the underlying Recapture Member are characterized by preservation of Fe-Ti oxide grains, primarily magnetite and ilmenite, and of hematite, and by an absence or uranium concentrations. Partly destroyed Fe-Ti oxide minerals occupy an interval between the zones of destruction and preservation. Alteration patterns of the Fe-Ti oxide minerals are reflected in bore-hole magnetic susceptibility logs. Magnetic susceptibility response in the upper parts of the Westwater Canyon Member is flat and uniformly <500 μSI units, but at greater depths it fluctuates sharply, from <1,000 to nearly 8,000 μSI units. The boundary between uniformly low and high magnetic susceptibility response corresponds closely to the interval that divides the zone of completely altered from the zone of preserved detrital Fe-Ti oxide minerals. The alteration pattern suggests that solutions responsible for destruction of the Fe-ti oxide minerals originated in the overlying Brushy Basin Member of the Morrison Formation. Previous studies indicate that these solutions were rich in soluble organic matter and perhaps in uranium. Uranium precipitation may have been controlled by a vertically fluctuation interface between organic-rich solutions and geochemically different fluids in which the detrital Fe-Ti oxide minerals were preserved

  17. Neutron diffraction studies of magnetic ordering in superconducting ErNi2B2C and TmNi2B2C in an applied magnetic field

    DEFF Research Database (Denmark)

    Toft, Katrine Nørgaard

    The field-induced magnetic structures of ErNi2B2C and TmNi2B2C in are especially interesting because the field suppresses the superconducting order parameter and therefore the magnetic properties can be studied while varying the strength ofsuperconductivity. ErNi2B2C: For magnetic fields along all.......483,0,0). The appearance of the QN phase wasinitially believed to be caused by the suppression of superconductivity. This suppression should make it favorable to create a magnetic order with a Q-vector determined by the maximum in the magnetic susceptibility at the Fermi surface nesting vector QN.The phase diagram...... three symmetry directions, the observed magnetic structures have a period corresponding to the Fermi surface nesting structure. The phase diagrams present all the observed magnetic structures.Two results remain unresolved: 1. When applying the magnetic field along [010], the minority domain (QNB = (0,Q...

  18. Environmental magnetic studies on some Quaternary sediments of varied depositional settings in the Indian sub-continent

    Digital Repository Service at National Institute of Oceanography (India)

    Sangode, S.J.; Sinha, R.; Phartiyal, B.; Chauhan, O.S.; Mazari, R.K.; Bagati, T.N.; Suresh, N.; Mishra, S.; Kumar, R.; Bhattacharjee, P.

    susceptibility, high field hysteresis parameters and their ratios and bivariate plots. Besides applying the conventional models, new and multi-parametric environmental magnetic models for finer discrimination of the mineral magnetic assemblages (MMA) amongst...

  19. Effects of white matter microstructure on phase and susceptibility maps.

    Science.gov (United States)

    Wharton, Samuel; Bowtell, Richard

    2015-03-01

    To investigate the effects on quantitative susceptibility mapping (QSM) and susceptibility tensor imaging (STI) of the frequency variation produced by the microstructure of white matter (WM). The frequency offsets in a WM tissue sample that are not explained by the effect of bulk isotropic or anisotropic magnetic susceptibility, but rather result from the local microstructure, were characterized for the first time. QSM and STI were then applied to simulated frequency maps that were calculated using a digitized whole-brain, WM model formed from anatomical and diffusion tensor imaging data acquired from a volunteer. In this model, the magnitudes of the frequency contributions due to anisotropy and microstructure were derived from the results of the tissue experiments. The simulations suggest that the frequency contribution of microstructure is much larger than that due to bulk effects of anisotropic magnetic susceptibility. In QSM, the microstructure contribution introduced artificial WM heterogeneity. For the STI processing, the microstructure contribution caused the susceptibility anisotropy to be significantly overestimated. Microstructure-related phase offsets in WM yield artifacts in the calculated susceptibility maps. If susceptibility mapping is to become a robust MRI technique, further research should be carried out to reduce the confounding effects of microstructure-related frequency contributions. © 2014 Wiley Periodicals, Inc.

  20. Magnetic Resonance Imaging of Surgical Implants Made from Weak Magnetic Materials

    Science.gov (United States)

    Gogola, D.; Krafčík, A.; Štrbák, O.; Frollo, I.

    2013-08-01

    Materials with high magnetic susceptibility cause local inhomogeneities in the main field of the magnetic resonance (MR) tomograph. These inhomogeneities lead to loss of phase coherence, and thus to a rapid loss of signal in the image. In our research we investigated inhomogeneous field of magnetic implants such as magnetic fibers, designed for inner suture during surgery. The magnetic field inhomogeneities were studied at low magnetic planar phantom, which was made from four thin strips of magnetic tape, arranged grid-wise. We optimized the properties of imaging sequences with the aim to find the best setup for magnetic fiber visualization. These fibers can be potentially exploited in surgery for internal stitches. Stitches can be visualized by the magnetic resonance imaging (MRI) method after surgery. This study shows that the imaging of magnetic implants is possible by using the low field MRI systems, without the use of complicated post processing techniques (e.g., IDEAL).

  1. Gd3+-ESR and magnetic susceptibility of GdCu4Al8 and GdMn4Al8

    International Nuclear Information System (INIS)

    Coldea, R.; Coldea, M.; Pop, I.

    1994-01-01

    Gd ESR of GdCu 4 Al 8 and GdMn 4 Al 8 and magnetic susceptibility of GdCu 4 Al 8 , GdMn 4 Al 8 , and YMn 4 Al 8 were measured in the temperature range of 290K--460K and 90K--1050K, respectively. The occurrence of the Mn moment in YMn 4 Al 8 and GdMn 4 Al 8 is strongly correlated with the critical value of d∼2.6 angstrom of the Mn-Mn distance below which the Mn moment is not stable. The experimental data for GdMn 4 Al 8 , compared with the data for the isostructural compounds GdCu 4 Al 8 and YMn 4 Al 8 , show that near the critical value of d, the existence of Mn moment depends not only on the value of d, but also on the local magnetic surroundings. It has been revealed that the magnetic character of Mn moment in YMn 4 Al 8 and GdMn 4 Al 8 changes from an itinerant electron type to a local-moment type with increasing temperature

  2. Use of Magnetic Parameters to Asses Soil Erosion Rates on Agricultural Site

    Science.gov (United States)

    Petrovsky, E.; Kapicka, A.; Dlouha, S.; Jaksik, O.; Grison, H.; Kodesova, R.

    2014-12-01

    A detailed field study on a small test site of agricultural land situated in loess region in Southern Moravia (Czech Republic) and laboratory analyses were carried out in order to test the applicability of magnetic methods in assessing soil erosion. Haplic Chernozem, the original dominant soil unit in the area, is nowadays progressively transformed into different soil units along with intense soil erosion. As a result, an extremely diversified soil cover structure has developed due to the erosion. The site was characterized by a flat upper part while the middle part, formed by a substantive side valley, is steeper. We carried out field measurements of magnetic susceptibility on a regular grid, resulting in 101 data points. The bulk soil material for laboratory investigation was gathered from all the grid points. Values of the magnetic susceptibility are spatially distributed depending on the terrain. Higher values were measured in the flat upper part (where the original top horizon remained). The lowest values of were obtained on the steep valley sides. Here the original topsoil was eroded and mixed by tillage with the soil substrate (loess). A soil profile unaffected by erosion was investigated in detail. The vertical distribution of magnetic susceptibility along this "virgin" profile was measured in laboratory on the samples collected with 2-cm spacing. The undisturbed profile shows several soil horizons. Horizons Ac and A show a slight increase in magnetic susceptibility up to a depth of about 70 cm. Horizon A/Ck is characterized by a decrease in susceptibility, and the underlying C horizon (h > 103 cm) has a very low value of magnetic susceptibility. The differences between the values of susceptibility in the undisturbed soil profile and the magnetic signal after uniform mixing the soil material as a result of tillage and erosion are fundamental for the estimation of soil loss in the studied test field. Using the uneroded profile from the studied locality as a

  3. Application of the magnetic fluid as a detector for changing the magnetic field

    Science.gov (United States)

    Zyatkov, D.; Yurchenko, A.; Yurchenko, V.; Balashov, V.

    2018-05-01

    In article the possibility of use of magnetic fluid as a sensitive element for fixing of change of induction of magnetic field in space is considered. Importance of solvable tasks is connected with search of the perspective magnetic substances susceptible to weak magnetic field. The results of a study of the capacitive method for fixing the change in the magnetic field on the basis of a ferromagnetic liquid are presented. The formation of chain structures in the ferrofluid from magnetic particles under the influence of the applied magnetic field leads to a change in the capacitance of the plate condenser. This task has important practical value for development of a magnetosensitive sensor of change of magnetic field.

  4. 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.

  5. Microfluidic high gradient magnetic cell separation

    Science.gov (United States)

    Inglis, David W.; Riehn, Robert; Sturm, James C.; Austin, Robert H.

    2006-04-01

    Separation of blood cells by native susceptibility and by the selective attachment of magnetic beads has recently been demonstrated on microfluidic devices. We discuss the basic principles of how forces are generated via the magnetic susceptibility of an object and how microfluidics can be combined with micron-scale magnetic field gradients to greatly enhance in principle the fractionating power of magnetic fields. We discuss our efforts and those of others to build practical microfluidic devices for the magnetic separation of blood cells. We also discuss our attempts to integrate magnetic separation with other microfluidic features for developing handheld medical diagnostic tools.

  6. Rock magnetism of the offshore soils of Lake Qinghai in the western China

    Directory of Open Access Journals (Sweden)

    Peng eZhang

    2016-05-01

    Full Text Available Lake Qinghai is the largest lake in China and situated in an important climate-sensitive zone on the northeastern margin of the Tibetan Plateau, making it an ideal place to study the environmental evolution of the northwest China as well as the interplay between the Asian monsoon and the westerlies in late Quaternary. In this study, detailed rock magnetic measurements were carried out on the offshore soils of Lake Qinghai. The dry grassland samples have higher magnetic susceptibility than that of the wet grassland samples, which suggests a higher concentration of magnetic minerals in the dry grassland and lower concentration of magnetic minerals in the wet grassland near the lake edge. The high concentration of the superparamagnetic (SP magnetic minerals related to pedogenesis may also contribute to the high magnetic susceptibility of the dry grassland. The low magnetic susceptibility of the wet grassland may result from the conversion of strongly to weakly magnetic minerals and/or the dissolution of magnetic minerals. In addition, the Hm/(Gt+Hm value has a positive correlation with the water content, thus can be taken as an effective proxy for the soil moisture.

  7. A preliminary magnetic study of Sawa lake sediments, Southern Iraq

    Science.gov (United States)

    Ameen, Nawrass

    2016-04-01

    A preliminary magnetic study combined with chemical analyses was carried out in Sawa Lake in Al-Muthanna province, southern Iraq, about 22 km south west of Samawa city (31°18'48.80"N, 45°0'25.25"E). The lake is about 4.74 km length, 1.75 km width and 5.5 m height, it is surrounded by a salt rim which is higher than the lake water by about 2.8 m and sea water by about 18.5 m (Naqash et al., 1977 in Hassan, 2007). The lake is an elongated closed basin with no surface water available to it, it may be fed by groundwater of the Euphrates and Dammam aquifers through system of joints and cracks. This study aims to investigate the concentrations of selected heavy metals as pollutants and magnetic susceptibility (MS) and other magnetic properties of sediment samples from fifty sites collected from the bottom of the lake, the study area lies in an industrial area. The results show spatial variations of MS with mean value of about 4.58 x 10-8 m3 kg-1. Scanning electron microscopy and magnetic mineralogy parameters indicate the dominance of soft magnetic phase like magnetite and presence of hard magnetic phase like hematite. Spatial variations of MS combined with the concentrations of heavy metals suggests the efficiency of magnetic methods as effective, inexpensive and non-time consuming method to outlining the heavy metal pollution. References: Hassan W.F., 2007. The Physio-chemical characteristic of Sawa lake water in Samawa city-Iraq. Marine Mesopotamica, 22(2), 167-179.

  8. Magnetic properties of Surabaya river sediments, East Java, Indonesia

    Science.gov (United States)

    Mariyanto, Bijaksana, Satria

    2017-07-01

    Surabaya river is one of urban rivers in East Java Province, Indonesia that is a part of Brantas river that flows in four urban and industrial cities of Mojokerto, Gresik, Sidoarjo, and Surabaya. The urban populations and industries along the river pose serious threat to the river mainly for their anthropogenic pollutants. This study aims to characterize the magnetic properties of sediments in various locations along Surabaya river and correlate these magnetic properties to the level of pollution along the river. Samples are taken and measured through a series of magnetic measurements. The mass-specific magnetic susceptibility of sediments ranges from 259.4 to 1134.8 × 10-8 m3kg-1. The magnetic minerals are predominantly PSD to MD magnetite with the grain size range from 6 to 14 μm. The mass-specific magnetic susceptibility tends to decreases downstream as accumulation of magnetic minerals in sediments is affected not only by the amount of household and industrial wastes but also by sediment dredging, construction of embankments, and extensive erosion arround the river. Sediments located in the industrial zone on the upstream area tend to have higher mass-specific magnetic susceptibility than in the non-industrial zones on the downstream area.

  9. Magnetic properties of dendrimer structures with different coordination numbers: A Monte Carlo study

    International Nuclear Information System (INIS)

    Masrour, R.; Jabar, A.

    2016-01-01

    We investigate the magnetic properties of Cayley trees of large molecules with dendrimer structure using Monte Carlo simulations. The thermal magnetization and magnetic susceptibility of a dendrimer structure are given with different coordination numbers, Z=3, 4, 5 and different generations g=3 and 2. The variation of magnetizations with the exchange interactions and crystal fields have been given of this system. The magnetic hysteresis cycles have been established. - Highlights: • The dendrimer structure is investigated using Monte Carlo simulations. • The transition temperatures are obtained for different coordination numbers and generations. • The magnetic hysteresis cycle has been established. • The dendrimer structure exhibit the superparamagnetic behavior.

  10. Magnetic properties of dendrimer structures with different coordination numbers: A Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Masrour, R., E-mail: rachidmasrour@hotmail.com; Jabar, A.

    2016-11-01

    We investigate the magnetic properties of Cayley trees of large molecules with dendrimer structure using Monte Carlo simulations. The thermal magnetization and magnetic susceptibility of a dendrimer structure are given with different coordination numbers, Z=3, 4, 5 and different generations g=3 and 2. The variation of magnetizations with the exchange interactions and crystal fields have been given of this system. The magnetic hysteresis cycles have been established. - Highlights: • The dendrimer structure is investigated using Monte Carlo simulations. • The transition temperatures are obtained for different coordination numbers and generations. • The magnetic hysteresis cycle has been established. • The dendrimer structure exhibit the superparamagnetic behavior.

  11. Can Dynamic Susceptibility Contrast Magnetic Resonance Imaging Replace Single-Photon Emission Computed Tomography in the Diagnosis of Patients with Alzheimer's Disease? A Pilot Study

    International Nuclear Information System (INIS)

    Cavallin, L.; Danielsson, R.; Oeksengard, A.R.; Wahlund, L.O.; Julin, P.; Frank, A.; Engman, E.L.; Svensson, L.; Kristoffersen Wiberg, M.

    2006-01-01

    Purpose: To compare single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI) in a cohort of patients examined for suspected dementia, including patients with no objective cognitive impairment (control group), mild cognitive impairment (MCI), and Alzheimer's disease (AD). Material and Methods: Twenty-four patients, eight with AD, 10 with MCI, and six controls were investigated with SPECT using 99m Tc-hexamethylpropyleneamine oxime (HMPAO) and dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) with gadobutrol. Three observers performed a visual interpretation of the SPECT and MR images using a four-point visual scale. Results: SPECT was superior to DSC-MRI in differentiating normal from pathological. All three observers showed statistically significant results in discriminating between the control group, AD, and MCI by SPECT, with a P value of 0.0006, 0.04, and 0.01 for each observer. The statistical results were not significant for MR (P values 0.8, 0.1, and 0.2, respectively). Conclusion: DSC-MRI could not replace SPECT in the diagnosis of patients with Alzheimer's disease. Several patient- and method-related improvements should be made before this method can be recommended for clinical practice

  12. Enhanced Methods to Estimate the Efficiency of Magnetic Nanoparticles in Imaging

    Directory of Open Access Journals (Sweden)

    Ann M. Hirt

    2017-12-01

    Full Text Available Magnetic resonance imaging (MRI and magnetic particle imaging (MPI are powerful methods in the early diagnosis of diseases. Both imaging techniques utilize magnetic nanoparticles that have high magnetic susceptibility, strong saturation magnetization, and no coercivity. FeraSpinTM R and its fractionated products have been studied for their imaging performances; however, a detailed magnetic characterization in their immobilized state is still lacking. This is particularly important for applications in MPI that require fixation of magnetic nanoparticles with the target cells or tissues. We examine the magnetic properties of immobilized FeraSpinTM R, its size fractions, and Resovist®, and use the findings to demonstrate which magnetic properties best predict performance. All samples show some degree of oxidation to hematite, and magnetic interaction between the particles, which impact negatively on image performance of the materials. MRI and MPI performance show a linear dependency on the slope of the magnetization curve, i.e., initial susceptibility, and average blocking temperature. The best performance of particles in immobilized state for MPI is found for particle sizes close to the boundary between superparamagnetic (SP and magnetically ordered, in which only Néel relaxation is important. Initial susceptibility and bifurcation temperature are the best indicators to predict MRI and MPI performance.

  13. Helical patterns of magnetization and magnetic charge density in iron whiskers

    Science.gov (United States)

    Templeton, Terry L.; Hanham, Scott D.; Arrott, Anthony S.

    2018-05-01

    Studies with the (1 1 1) axis along the long axis of an iron whisker, 40 years ago, showed two phenomena that have remained unexplained: 1) In low fields, there are six peaks in the ac susceptibility, separated by 0.2 mT; 2) Bitter patterns showed striped domain patterns. Multipole columns of magnetic charge density distort to form helical patterns of the magnetization, accounting for the peaks in the susceptibility from the propagation of edge solitons along the intersections of the six sides of a (1 1 1) whisker. The stripes follow the helices. We report micromagnetic simulations in cylinders with various geometries for the cross-sections from rectangular, to hexagonal, to circular, with wide ranges of sizes and lengths, and different anisotropies, including (0 0 1) whiskers and the hypothetical case of no anisotropy. The helical patterns have been there in previous studies, but overlooked. The surface swirls and body helices are connected, but have their own individual behaviors. The magnetization patterns are more easily understood when viewed observing the scalar divergences of the magnetization as isosurfaces of magnetic charge density. The plus and minus charge densities form columns that interact with unlike charges attracting, but not annihilating as they are paid for by a decrease in exchange energy. Just as they start to form the helix, the columns are multipoles. If one could stretch the columns, the self-energy of the charges in a column would be diminished while making the attractive interactions of the unlike charges larger. The columns elongate by becoming helical. The visualization of 3-D magnetic charge distributions aids in the understanding of magnetization in soft magnetic materials.

  14. Magnetic Properties of Dy in Pb2Sr2DyCu3O8

    International Nuclear Information System (INIS)

    Skanthakumar, S.; Soderholm, L.; Movshovich, R.

    1999-01-01

    Superconductivity can be induced at high temperatures in Pb 2 Sr 2 RCu 3 O 8 (R - rare earth) by partially doping Ca 2+ for R 3+ . In order to understand the interplay between magnetism and superconductivity, the magnetic properties of the parent compounds, Pb 2 Sr 2 RCu 3 O 8 , have been studied. The work presented here includes magnetic susceptibility and specific heat measurements on R=Dy and extends the previous studies on R=Ce, Pr, Tb, Ho and Er. Specific heat experiments suggest that the Dy ions order antiferromagnetically with an ordering temperature of 1.3K. The magnetic susceptibility data are in good agreement with the susceptibility calculated using crystal field parameters that are extrapolated from previous modeling of the R=Er and Ho analogs of this series

  15. A non-magnetic spacer layer effect on spin layers (7/2,3) in a bi-layer ferromagnetic dendrimer structure: Monte Carlo study

    Science.gov (United States)

    Jabar, A.; Tahiri, N.; Bahmad, L.; Benyoussef, A.

    2016-11-01

    A bi-layer system consisting of layers of spins (7/2, 3) in a ferromagnetic dendrimer structure, separated by a non-magnetic spacer, is studied by Monte Carlo simulations. The effect of the RKKY interactions is investigated and discussed for such system. It is shown that the magnetic properties in the two magnetic layers depend strongly on the thickness of the magnetic and non-magnetic layers. The total magnetizations and susceptibilities are studied as a function of the reduced temperature. The effect of the reduced exchange interactions as well as the reduced crystal field is outlined. On other hand, the critical temperature is discussed as a function of the magnetic layer values. To complete this study we presented and discussed the magnetic hysteresis cycles.

  16. Microstructure, magnetic and Moessbauer studies on spark-plasma sintered Sm-Co-Fe/Fe(Co) nanocomposite magnets

    Energy Technology Data Exchange (ETDEWEB)

    Rao, N V Rama; Saravanan, P; Gopalan, R; Raja, M Manivel; Rao, D V Sreedhara; Chandrasekaran, V [Defence Metallurgical Research Laboratory, Hyderabad-500 058 (India); Sivaprahasam, D [International Advanced Research Centre for Powder Metallurgy and New Materials Hyderabad-500 005 (India); Ranganathan, R [Saha Institute of Nuclear Physics, Kolkata-700 064 (India)], E-mail: rg_gopy@yahoo.com

    2008-03-21

    Nanocomposite powders comprising Sm-Co-Fe intermetallic phases and Fe(Co) were synthesized by high-energy ball milling and were consolidated into bulk magnets by the spark-plasma sintering (SPS) technique. While the microstructure of the SPS samples was characterized by transmission electron microscopy (TEM), the solubility of Fe in different phases was investigated using Moessbauer spectroscopy. TEM studies revealed that the spark-plasma sintered sample has Sm(Co,Fe){sub 5} as a major phase with Sm{sub 2}(Co,Fe){sub 17}, Sm(Co,Fe){sub 2} and Fe(Co) as secondary phases. The size of the nanocrystalline grains of all these phases was found to be in the range 50-100 nm. The Moessbauer spectra of the as-milled powders exhibited two different subspectra: a sextet corresponding to the Fe phase and a broad sextet associated with the Fe(Co) phase; while that of the SPS sample showed four different subspectra: a sextet corresponding to Fe and other three sextets corresponding to the Fe(Co), Sm(Co,Fe){sub 5} and Sm{sub 2}(Co,Fe){sub 17} phases; these results are in accordance with the TEM observation. Recoil magnetization and reversible susceptibility measurements revealed magnetically single phase behaviour of the SPS magnets.

  17. The use of total susceptibility in the analysis of long term PM10 (PM2.5) collected at Hungarian air quality monitoring stations

    Science.gov (United States)

    Márton, Emö; Domján, Ádám; Lautner, Péter; Szentmarjay, Tibor; Uram, János

    2013-04-01

    first, indicating that a sizable part of the magnetic grains is coming from nearby capitals rather than from more distant sources. We found no correlation between magnetic susceptibility and toxic metals. On the other hand the weaker vehicle traffic during week-ends, especially on Sundays is evident in the total susceptibilities, although it is also seen as a tendency in the mass of the pollutants and in the mass susceptibilities. While the generally used mass susceptibility seems to be useful as an indication for the heaviness of vehicle traffic in the area of the studied monitoring stations, it is a total failure for expressing correctly seasonal variations. The reason is that much more non-magnetic than magnetic pollutants are produced during heating season, especially by household heating with coal and wood. The consequence is that in the total susceptibility the higher production of the magnetic particles during heating season is evident, while in the mass susceptibility the trend is opposite, i.e. the magnetic pollution seems to be less intensive during heating season than otherwise. Acknowledgement: This work was financially supported by the Hungarian Scientific Research Fund (project no. OTKA K 75395).

  18. Magnetic Soils Profiles in the Volga-Kama Forest-Steppe Region

    Directory of Open Access Journals (Sweden)

    L.A. Fattakhova

    2016-09-01

    Full Text Available The magnetic properties of virgin forest-steppe soils developed on the originally vertically uniform unconsolidated parent material have been investigated. The profile samples of virgin dark-grey forest light-clayey soil derived from a siltstone of the Kazan layer of the Upper Permian and virgin leached medium-thick fertile light-clayey chernozem derived from a Quaternary heavy deluvial loam have been considered. Both soils are characterized by the accumulative type of magnetic susceptibility and F-factor values distribution patterns with depth. In the humus part of the soil profile, magnetics are present pre-dominantly in the < 2.5 µm fraction. The coercivity spectra allowed to determine the contribution of dia-/paramagnetic and ferromagnetic components to magnetic susceptibility. It has been found that magnetic susceptibility enhancement in the organogenic horizons of virgin forest-steppe soils occurs due to the contribution of ferromagnetic components. The results indicate a strong positive linear correlation between the magnetic susceptibility and oxalate-extractable Fe, as well as between the magnetic susceptibility and Schwertmann’s criterion values. Using the method of thermomagnetic analysis of the < 2.5 µm fraction, it has been found that the magnetic susceptibility enhancement in the profiles of forest-steppe soils took place due to the formation of maghemite-magnetite associations. The predominantly ferromagnetic fraction consists of small single-domain grains.

  19. Magnetic field dependent atomic tunneling in non-magnetic glasses

    International Nuclear Information System (INIS)

    Ludwig, S.; Enss, C.; Hunklinger, S.

    2003-01-01

    The low-temperature properties of insulating glasses are governed by atomic tunneling systems (TSs). Recently, strong magnetic field effects in the dielectric susceptibility have been discovered in glasses at audio frequencies at very low temperatures. Moreover, it has been found that the amplitude of two-pulse polarization echoes generated in non-magnetic multi-component glasses at radio frequencies and at very low temperatures shows a surprising non-monotonic magnetic field dependence. The magnitude of the latter effect indicates that virtually all TSs are affected by the magnetic field, not only a small subset of systems. We have studied the variation of the magnetic field dependence of the echo amplitude as a function of the delay time between the two excitation pulses and at different frequencies. Our results indicate that the evolution of the phase of resonant TSs is changed by the magnetic field

  20. Magnetic field dependent atomic tunneling in non-magnetic glasses

    Science.gov (United States)

    Ludwig, S.; Enss, C.; Hunklinger, S.

    2003-05-01

    The low-temperature properties of insulating glasses are governed by atomic tunneling systems (TSs). Recently, strong magnetic field effects in the dielectric susceptibility have been discovered in glasses at audio frequencies at very low temperatures. Moreover, it has been found that the amplitude of two-pulse polarization echoes generated in non-magnetic multi-component glasses at radio frequencies and at very low temperatures shows a surprising non-monotonic magnetic field dependence. The magnitude of the latter effect indicates that virtually all TSs are affected by the magnetic field, not only a small subset of systems. We have studied the variation of the magnetic field dependence of the echo amplitude as a function of the delay time between the two excitation pulses and at different frequencies. Our results indicate that the evolution of the phase of resonant TSs is changed by the magnetic field.

  1. Magnetic Properties and Phase Composition of Metamaterials Based on an Opal Matrix with 3 d-Transition Metal Particles

    Science.gov (United States)

    Rinkevich, A. B.; Korolev, A. V.; Samoilovich, M. I.; Perov, D. V.; Nemytova, O. V.

    2018-02-01

    The magnetic properties of metamaterials based on an opal matrix with transition-metal (iron, nickel, cobalt) particles have been studied. Magnetization curves and magnetic hysteresis loops have been measured and the dependences of real and imaginary parts of magnetization have been determined using the dynamic ac susceptibility measuring procedure. Structural studies of metamaterials have been performed. The saturation magnetization and coercive force of the studied metamaterials have been found to depend weakly on the temperature. The temperature dependence of magnetic susceptibility at a temperature above 30 K can be described adequately by Curie-Weiss law and, at lower temperature, deviates from the law.

  2. 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

  3. Magnetization reversal of a type-II superconductor thin disk under the action of a constant magnetic field

    International Nuclear Information System (INIS)

    Koval'chuk, D.G.; Chornomorets', M.P.

    2010-01-01

    The applicability of relations obtained by Clem and Sanchez for the ac magnetic susceptibility of type-II superconductor thin films to the case where an additional constant magnetic field is applied perpendicularly to the film has been analyzed in the framework of the critical state model. The issues concerning the sample 'memory' and the influence of the magnetic field change prehistory on the current sample state have been discussed. It has been shown that the ac component of the magnetic moment and, hence, the amplitudes of ac magnetic susceptibility harmonics are established within one period of the ac magnetic field irrespective of the field prehistory.

  4. An integrated rock magnetic and EPR study in soil samples from a hydrocarbon prospective area

    Science.gov (United States)

    González, F.; Aldana, M.; Costanzo-Álvarez, V.; Díaz, M.; Romero, I.

    Magnetic susceptibility (MS) and organic matter free radical concentration (OMFRC) determined by electron paramagnetic resonance, have been measured in soil samples (≈1.5 m depth) from an oil prospective area located at the southern flank of the Venezuelan Andean Range. S-ratios close to 1, as well as high temperature susceptibility analyses, reveal magnetite as the chief magnetic phase in most of these samples. Ethane concentrations, MS and OMFRC normalized data have been plotted against the relative position of 22 sampling sites sequentially arranged from north to south. Although there is not a linear correlation between MS and OMFRC data, these two profiles seem to vary in like fashion. A MS and OMFRC southern anomaly coincides with the zone of highest ethane concentration that overlies a “Cretaceous kitchen”. OMFRC highs could be linked to the degradation or alteration of organic matter, the possible result of hydrocarbon gas leakage, whose surface expression is the stressed fern observed by remote sensing studies previously performed in the area. Ethane anomalies are associated to this seepage that also produces changes in the magnetic mineralogies detected as MS positive anomalies.

  5. Magnetic and magneto-optical properties of CdS:Mn quantum dots in PVA matrix

    International Nuclear Information System (INIS)

    Fediv, V I; Savchuk, A I; Frasunyak, V M; Makoviy, V V; Savchuk, O A

    2010-01-01

    We have studied the magnetic and magneto-optical properties of CdS:Mn quantum dots in polyvinyl alcohol matrix synthesized by co-precipitation method. The size of quantum dots was estimated by means of absorption spectroscopy. The results of measurements of magnetic susceptibility as a function of temperature and spectral dependence of the Faraday rotation of CdS:Mn quantum dots / polyvinyl alcohol composites are presented. In this work magnetic susceptibility was investigated by Faraday's method at the temperatures of (78-300) K in magnetic fields of (0.05-0.8) T. The inverse magnetic susceptibility as a function of temperature follows a Curie Weiss law. Formation of ferromagnetic coupling between magnetic ions is supposed. Magneto-optical Faraday rotation has been investigated in the wavelength region (400-700) nm at temperature 300 K in a magnetic field up to 5 T. Sign of the Verdet constant is found to be negative.

  6. In Vitro Antibiotic Susceptibility Studies Of Bacteria Associated With ...

    African Journals Online (AJOL)

    In vitro tests of the susceptibility of isolates of bacterial keratitis pathogens to antibiotics were carried out in this study. Staphylococcus aureus was the most frequently isolated organisms followed by Pseudomonas aeruginosa and Streptococcus pneumoniae. Antibiotic sensitivity testing showed a high susceptibility to ...

  7. Magnetic Properties of One-Dimensional Ferromagnetic Mixed-Spin Model within Tyablikov Decoupling Approximation

    International Nuclear Information System (INIS)

    Chen Yuan; Song Chuangchuang; Xiang Ying

    2010-01-01

    In this paper, we apply the two-time Green's function method, and provide a simple way to study the magnetic properties of one-dimensional spin-(S,s) Heisenberg ferromagnets. The magnetic susceptibility and correlation functions are obtained by using the Tyablikov decoupling approximation. Our results show that the magnetic susceptibility and correlation length are a monotonically decreasing function of temperature regardless of the mixed spins. It is found that in the case of S=s, our results of one-dimensional mixed-spin model is reduced to be those of the isotropic ferromagnetic Heisenberg chain in the whole temperature region. Our results for the susceptibility are in agreement with those obtained by other theoretical approaches. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  8. Application of magnetic, geochemical and micro-morphological methods in environmental studies of urban pollution generated by road traffic

    Energy Technology Data Exchange (ETDEWEB)

    Bucko, M.

    2012-11-01

    Road traffic is at present one of the major sources of environmental pollution in urban areas. Magnetic particles, heavy metals and other compounds generated by traffic can greatly affect ambient air quality and have direct implications for human health. The general aim of this research was to identify and characterize magnetic vehicle-derived particulates using magnetic, geochemical and micro-morphological methods. A combination of three different methods was used to discriminate sources of particular anthropogenic particles. Special emphasis was placed on the application of various collectors (roadside soil, snow, lichens and moss bags) to monitor spatial and temporal distribution of traffic pollution on roadsides. The spatial distribution of magnetic parameters of road dust accumulated in roadside soil, snow, lichens and moss bags indicates that the highest concentration of magnetic particles is in the sampling points situated closest to the road edge. The concentration of magnetic particles decreases with increasing distance from the road indicating vehicle traffic as a major source of emission. Significant differences in horizontal distribution of magnetic susceptibility were observed between soil and snow. Magnetic particles derived from road traffic deposit on soil within a few meters from the road, but on snow up to 60 m from the road. The values of magnetic susceptibility of road dust deposited near busy urban motorway are significantly higher than in the case of low traffic road. These differences are attributed to traffic volume, which is 30 times higher on motorway than on local road. Moss bags placed at the edge of urban parks situated near major roads show higher values of magnetic susceptibility than moss bags from parks located near minor routes. Enhanced concentrations of heavy metals (e.g. Fe, Mn, Zn, Cu, Cr, Ni and Co) were observed in the studied samples. This may be associated with specific sources of vehicle emissions (e.g. exhaust and non

  9. Magnetic property and pressure effect of a single crystal CeRhGe

    International Nuclear Information System (INIS)

    Ueda, Taiki; Honda, Daisuke; Shiromoto, Tomoyuki; Thamizhavel, Arumugam; Sugiyama, Kiyohiro; Settai, Rikio; Onuki, Yoshichika; Metoki, Naoto; Honda, Fuminori; Kaneko, Koji; Haga, Yoshinori; Matsuda, Tatsuma D.; Kindo, Kouichi

    2005-01-01

    We measured the electrical resistivity, specific heat, magnetic susceptibility, high-field magnetization, neutron scattering and electrical resistivity under pressure for CeRhGe. The anisotropy of the magnetic susceptibility and magnetization are very large, reflecting the orthorhombic crystal structure. The magnetic easy-axis is found to be oriented along the a-axis. From the neutron scattering experiment, the magnetic structure is, however, not simple, indicating an incommensurate antiferromagnetic structure. The magnetic susceptibility and magnetization were analyzed on the basis of the crystalline electric field scheme of localized-4f energy levels, indicating a very large splitting energy of the 4f levels. (author)

  10. A mechanism for the downturn in inverse susceptibility in triangle-based frustrated spin systems

    International Nuclear Information System (INIS)

    Isoda, M

    2008-01-01

    A mechanism for the downturn of inverse magnetic susceptibility below an intermediate temperature, recently observed in many experiments, is proposed as an intrinsic feature of lattices with triangle-based frustrated geometries. The temperature at the bending of the inverse susceptibility curve may be related to the features of other thermodynamic properties; the hump of the specific heat and the emergence of a 1/3 plateau in magnetization under a magnetic field. This fact is derived through a Monte Carlo simulation study of the Ising model on triangular and kagome lattices, and the exact calculation for the single and small-sized triangle clusters, on both the Ising and Heisenberg models. These results may indicate the dominance of S(S z ) = 1/2 quantum (classical) trimer formation in the intermediate-energy regime in two-dimensional triangle-based lattices

  11. Rock magnetic signature of paleoenvironmental changes in the Izu Bonin rear arc over the last 1 Ma

    Science.gov (United States)

    Kars, Myriam; Vautravers, Maryline; Musgrave, Robert; Kodama, Kazuto

    2015-04-01

    During April and May 2014, IODP Expedition 350 drilled a 1806.5 m deep hole at Site U1437 in the Izu-Bonin rear arc, in order to understand, among other objectives, the compositional evolution of the arc since the Miocene and track the missing half of the subduction factory. The good recovery of mostly fine grained sediments at this site enables a high resolution paleontological and rock magnetic studies. Particularly, variations in magnetic properties and mineralogy are well documented. Natural remanent magnetization and magnetic susceptibility vary with a saw-tooth pattern. Routine rock magnetic measurements performed on about 400 samples in the first 120 meters of Hole U1437B showed that pseudo single domain to multidomain magnetite is the main carrier of the remanence. The origin of magnetite is likely detrital. The magnetic susceptibility variations depend on many factors (e.g. lithology, magnetic mineralogy, and also dilution by the carbonate matrix). The magnetic susceptibility is also used as a proxy, at first order, for magnetic minerals concentration. In order to highlight changes in magnetic minerals concentration, it's necessary to correct for the carbonate dilution effect. Onboard and onshore carbonate measurements by coulometry show that the carbonate content of the samples can be up to ~60%. About 70 samples were measured onshore. After correcting the susceptibility by the carbonate content measured on the same samples, it appears that the pattern of the magnetic susceptibility before and after correction is similar. Then the magnetic susceptibility variations do not result from carbonate dilution but reflect fluctuating influx of the detrital sediment component. The delta O18 variations obtained on foraminifers (N. dutertrei) show MIS 1 to MIS 25 over the studied interval covering the last 1 Ma (see Vautravers et al., this meeting). Rock magnetic properties, concentration and grain size variations of the magnetic minerals will be compared to

  12. Fine particle magnetic mineralogy of archaeological ceramics

    International Nuclear Information System (INIS)

    Atkinson, D; King, J A

    2005-01-01

    This study investigated the magnetic mineralogy of a worldwide collection of archaeological pottery. The mineral types, the mass fractions and the domain states of the constituent magnetic fine particles were elucidated from a range of measurements including magnetic hysteresis behaviour, the acquisition of isothermal remanence, low field susceptibility and thermomagnetic curves. The magnetic mineralogy of most samples was dominated by magnetite. Titanomagnetites with limited titanium substitution and cation deficient magnetites (indicative of low temperature oxidation) were dominant in some samples. Haematite was detected in 53% of the samples, but seldom contributed much to the saturation magnetization. Magnetic particle sizes are skewed to smaller sizes, with sherds mostly having a large superparamagnetic or a stable single domain fraction. Low temperature susceptibility data suggest that 30% of samples had some multidomain component. The percentage by mass of magnetic material in the ancient pottery studied was less than 0.8% for all but one of the samples and the majority of samples contain less than 0.3% by weight of magnetic fine particles. The presence of low temperature oxidation in many samples and the occurrence of a multidomain component in a third of the collection suggest that ancient pottery may not always be suitable for determining the intensity of the ancient geomagnetic field

  13. Perfusion MRI of brain tumours: a comparative study of pseudo-continuous arterial spin labelling and dynamic susceptibility contrast imaging

    Energy Technology Data Exchange (ETDEWEB)

    Jaernum, Hanna; Steffensen, Elena G.; Simonsen, Carsten Wiberg; Jensen, Finn Taagehoej [Aalborg Hospital/Aarhus University Hospital, Department of Radiology, Aalborg (Denmark); Knutsson, Linda [Lund University, Department of Medical Radiation Physics, Lund (Sweden); Fruend, Ernst-Torben [Aalborg Hospital/Aarhus University Hospital, Department of Radiology, Aalborg (Denmark); GE Healthcare - Applied Science Lab Europe, Aalborg (Denmark); Lundbye-Christensen, Soeren [Aalborg Hospital/Aarhus University Hospital, Department of Cardiology, Center for Cardiovascular Research, Aalborg (Denmark); Shankaranarayanan, Ajit [Global Applied Science Lab, GE Healthcare, Menlo Park, CA (United States); Alsop, David C. [Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA (United States); Larsson, Elna-Marie [Aalborg Hospital/Aarhus University Hospital, Department of Radiology, Aalborg (Denmark); Uppsala University Hospital, Department of Radiology, Uppsala (Sweden)

    2010-04-15

    The purpose of this study was to compare the non-invasive 3D pseudo-continuous arterial spin labelling (PC ASL) technique with the clinically established dynamic susceptibility contrast perfusion magnetic resonance imaging (DSC-MRI) for evaluation of brain tumours. A prospective study of 28 patients with contrast-enhancing brain tumours was performed at 3 T using DSC-MRI and PC ASL with whole-brain coverage. The visual qualitative evaluation of signal enhancement in tumour was scored from 0 to 3 (0 = no signal enhancement compared with white matter, 3 = pronounced signal enhancement with equal or higher signal intensity than in grey matter/basal ganglia). The extent of susceptibility artefacts in the tumour was scored from 0 to 2 (0 = no susceptibility artefacts and 2 = extensive susceptibility artefacts (maximum diameter > 2 cm)). A quantitative analysis was performed with normalised tumour blood flow values (ASL nTBF, DSC nTBF): mean value for region of interest (ROI) in an area with maximum signal enhancement/the mean value for ROIs in cerebellum. There was no difference in total visual score for signal enhancement between PC ASL and DSC relative cerebral blood flow (p = 0.12). ASL had a lower susceptibility-artefact score than DSC-MRI (p = 0.03). There was good correlation between DSC nTBF and ASL nTBF values with a correlation coefficient of 0.82. PC ASL is an alternative to DSC-MRI for the evaluation of perfusion in brain tumours. The method has fewer susceptibility artefacts than DSC-MRI and can be used in patients with renal failure because no contrast injection is needed. (orig.)

  14. High field surface magnetic study of Fe{sub 3}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kihal, A. [Laboratoire de Magnetisme et Spectroscopie des Solides (LM2S), Universite Badji Mokhtar, BP-12 Annaba (Algeria); LNCMI-G, CNRS-UJF, 25 Rue des Martyrs, BP-166, 38042 Grenoble-Cedex 9 (France); Fillion, G. [LNCMI-G, CNRS-UJF, 25 Rue des Martyrs, BP-166, 38042 Grenoble-Cedex 9 (France); Bouzabata, B. [Laboratoire de Magnetisme et Spectroscopie des Solides (LM2S), Universite Badji Mokhtar, BP-12 Annaba (Algeria); Barbara, B. [Institut Neel, CNRS-UJF, 25 Rue des Martyrs, BP-166, 38042 Grenoble-Cedex 9 (France)

    2012-03-15

    Magnetic properties of magnetite (Fe{sub 3}O{sub 4}) powders, milled for various times up to 15 h, are studied by magnetization measurements. For the starting powder, like in the bulk single crystal, the approach to magnetic saturation is mainly ruled by the usual 1/H and 1/H{sup 2} terms. But for the milled samples, as the grain size decreases, a 1/H{sup 1/2} term rises as the leading term and is interpreted in the framework of the theory of Chudnovsky et al. accounting for the effect of a random anisotropy generated near the surface, aside from a large constant high field susceptibility related to the canted spins at the surface. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Magnetic properties of a single iron atomic chain encapsulated in armchair carbon nanotubes: A Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Masrour, R., E-mail: rachidmasrour@hotmail.com [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, PB 63, 46000 Safi (Morocco); Jabar, A. [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, PB 63, 46000 Safi (Morocco); Hamedoun, M. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Benyoussef, A. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco); Hlil, E.K. [Institut Néel, CNRS, Université Grenoble Alpes, 25 rue des Martyrs BP 166, 38042 Grenoble cedex 9 (France)

    2017-06-15

    Highlights: • Magnetic properties of Fe atom chain wrapped in armchair carbon nanotubes have been studied. • Transition temperature of iron and carbon have been calculated using Monte Carlo simulations. • The multiples magnetic hysteresis have been found. - Abstract: The magnetic properties have been investigated of FeCu{sub x}C{sub 1−x} for a Fe atom chain wrapped in armchair (N,N) carbon nanotubes (N = 4,6,8,10,12) diluted by Cu{sup 2+} ions using Monte Carlo simulations. The thermal total magnetization and magnetic susceptibility are found. The reduced transition temperatures of iron and carbon have been calculated for different N and the exchange interactions. The total magnetization is obtained for different exchange interactions and crystal field. The Magnetic hysteresis cycles are obtained for different N, the reduced temperatures and exchange interactions. The multiple magnetic hysteresis is found. This system shows it can be used as magnetic nanostructure possessing potential current and future applications in permanent magnetism, magnetic recording and spintronics.

  16. Magnetic fields and density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Salsbury Jr., Freddie [Univ. of California, Berkeley, CA (United States)

    1999-02-01

    A major focus of this dissertation is the development of functionals for the magnetic susceptibility and the chemical shielding within the context of magnetic field density functional theory (BDFT). These functionals depend on the electron density in the absence of the field, which is unlike any other treatment of these responses. There have been several advances made within this theory. The first of which is the development of local density functionals for chemical shieldings and magnetic susceptibilities. There are the first such functionals ever proposed. These parameters have been studied by constructing functionals for the current density and then using the Biot-Savart equations to obtain the responses. In order to examine the advantages and disadvantages of the local functionals, they were tested numerically on some small molecules.

  17. Magnetic fields and density functional theory

    International Nuclear Information System (INIS)

    Salsbury, Freddie Jr.

    1999-01-01

    A major focus of this dissertation is the development of functionals for the magnetic susceptibility and the chemical shielding within the context of magnetic field density functional theory (BDFT). These functionals depend on the electron density in the absence of the field, which is unlike any other treatment of these responses. There have been several advances made within this theory. The first of which is the development of local density functionals for chemical shieldings and magnetic susceptibilities. There are the first such functionals ever proposed. These parameters have been studied by constructing functionals for the current density and then using the Biot-Savart equations to obtain the responses. In order to examine the advantages and disadvantages of the local functionals, they were tested numerically on some small molecules

  18. The resonance susceptibility of two-layer exchange-coupled ferromagnetic film with a combined uniaxial and cubic anisotropy in the layers

    Energy Technology Data Exchange (ETDEWEB)

    Shul’ga, N.V., E-mail: shulga@anrb.ru; Doroshenko, R.A.

    2016-12-01

    A numerical investigation of the resonance dynamic susceptibility of ferromagnetic exchange-coupled two-layer films with a combined cubic and uniaxial magnetic anisotropy of the layers has been performed. It has been found that the presence of cubic anisotropy leads to the fact that much of the off-diagonal components of the dynamic susceptibility are nonzero. The change of the ferromagnetic resonance frequencies and dynamic susceptibility upon the magnetization along the [100], [010], and [011] directions have been calculated. The evolution of the profile of the dynamic susceptibility occurring during the magnetization has been described. The impact of changes in the distribution of equilibrium and dynamic components of the magnetization on the dependences of the components of the dynamic susceptibility and the ferromagnetic resonance frequency on the external magnetic fields has been discussed. - Highlights: • The extremes in the dependences of integrated dynamic susceptibility components are observed at low fields. • Lower extremes can be observed at a shift of the localization of the lower FMR mode toward the interface between the layers. • The features of the distribution of the dynamic susceptibility over the thickness have been discussed. • The cubic anisotropy leads to the fact that the off-diagonal integrated dynamic susceptibility components are essential. • FMR signal can be excited in vicinity of the interlayer boundary.

  19. Whole tissue AC susceptibility after superparamagnetic iron oxide contrast agent administration in a rat model

    International Nuclear Information System (INIS)

    Lazaro, Francisco Jose; Gutierrez, Lucia; Rosa Abadia, Ana; Soledad Romero, Maria; Lopez, Antonio; Jesus Munoz, Maria

    2007-01-01

    A magnetic AC susceptibility characterisation of rat tissues after intravenous administration of superparamagnetic iron oxide (Endorem ( R)), at the same dose as established for Magnetic Resonance Imaging (MRI) contrast enhancement in humans, has been carried out. The measurements reveal the presence of the contrast agent as well as that of physiological ferritin in liver and spleen while no traces have been magnetically detected in heart and kidney. This preliminary work opens suggestive possibilities for future biodistribution studies of any type of magnetic carriers

  20. Magnetic Order and Crystal Field Excitations in Er2Ru2O7: A Neutron Scattering Study

    International Nuclear Information System (INIS)

    Ehlers, Georg; Gardner, Jason

    2009-01-01

    The magnetic pyrochlore Er 2 Ru 2 O 7 has been studied with neutron scattering and susceptibility measurements down to a base temperature of 270 mK. For the low temperature phase in which the Er sublattice orders, new magnetic Bragg peaks are reported which can be indexed with integer (hkl) for a face centered cubic cell. Inelastic measurements reveal a wealth of crystal field levels of the Er ion and a copious amount of magnetic scattering below 15 meV. The three lowest groups of crystal field levels are at 6.7, 9.1 and 18.5 meV.

  1. Magnetic Viscosity for Cyclostratigraphic Logging of Argillaceous Sediment

    Directory of Open Access Journals (Sweden)

    Alain Tabbagh

    2009-09-01

    Full Text Available Magnetic susceptibility (MS is currently used as a directly representative proxy for the study of climatic variations, and for cyclostratigraphic studies. It depends on the concentration of magnetic minerals in the rocks, but does not allow identifying the magnetic minerals. In the case of argillaceous sediments, the paramagnetism of clay particles often plays a major role in determining the magnitude of their magnetic susceptibility, while the presence of ferrimagnetic iron oxides or sulfides cannot be assessedusing susceptibility measurements alone. Among the different methods that can be used to detect ferrimagnetic particles magnetic viscosity (MV characterizing the delay corresponding to the acquisition or loss of induced magnetization, has the same advantages as MS. Itsmeasurement is direct, rapid and has been proven to be very efficient in detecting the presence of secondary ferrimagnetic minerals in soils. A MV measurement technique was tested on cores taken from a borehole, in Callovian-Oxfordian formations in the eastern Paris Basin (France (Fig. 1. Although the MV values are very small, they have cyclic variations of which strongest values are found at the base of the Lower Oxfordian. These values, when correlated to MS,Gamma Ray (GR and a sequential interpretation of a borehole drilled close-by are found to be associated with the maximum clay fraction in the core samples, a MS maximum, and a major transgression event. Consequently, a significant increase in ferrimagnetic minerals can be associated with this event.

  2. Tectono-sedimentary analysis using the anisotropy of magnetic susceptibility: a study of the terrestrial and freshwater Neogene of the Orava Basin

    Science.gov (United States)

    Łoziński, Maciej; Ziółkowski, Piotr; Wysocka, Anna

    2017-10-01

    The Orava Basin is an intramontane depression filled with presumably fine-grained sediments deposited in river, floodplain, swamp and lake settings. The basin infilling constitutes a crucial record of the neoalpine evolution of the Inner/Outer Carpathian boundary area since the Neogene, when the Jurassic-Paleogene basement became consolidated, uplifted and eroded. The combination of sedimentological and structural studies with anisotropy of magnetic susceptibility (AMS) measurements provided an effective tool for recognition of terrestrial environments and deformations of the basin infilling. The lithofacies-oriented sampling and statistical approach to the large dataset of AMS specimens were utilized to define 12 AMS facies based on anisotropy degree (P) and shape (T). The AMS facies allowed a distinction of sedimentary facies ambiguous for classical methods, especially floodplain and lacustrine sediments, as well as revealing their various vulnerabilities to tectonic modification of AMS. A spatial analysis of facies showed that tuffites along with lacustrine and swamp deposits were generally restricted to marginal and southern parts of the basin. Significant deformations were noticed at basin margins and within two intrabasinal tectonic zones, which indicated the tectonic activity of the Pieniny Klippen Belt after the Middle Miocene. The large southern area of the basin recorded consistent N-NE trending compression during basin inversion. This regional tectonic rearrangement resulted in a partial removal of the southernmost basin deposits and shaped the basin's present-day extent.

  3. Rock magnetic characterization of faulted sediments with associated magnetic anomalies in the Albuquerque Basin, Rio Grande rift, New Mexico

    Science.gov (United States)

    Hudson, M.R.; Grauch, V.J.S.; Minor, S.A.

    2008-01-01

    Variations in rock magnetic properties are responsible for the many linear, short-wavelength, low-amplitude magnetic anomalies that are spatially associated with faults that cut Neogene basin sediments in the Rio Grande rift, including the San Ysidro normal fault, which is well exposed in the northern part of the Albuquerque Basin. Magnetic-susceptibility measurements from 310 sites distributed through a 1200-m-thick composite section of rift-filling sediments of the Santa Fe Group and prerift Eocene and Cretaceous sedimentary rocks document large variations of magnetic properties juxtaposed by the San Ysidro fault. Mean volume magnetic susceptibilities generally increase upsection through eight map units: from 1.7 to 2.2E-4 in the prerift Eocene and Cretaceous rocks to 9.9E-4-1.2E-3 in three members of the Miocene Zia Formation of the Santa Fe Group to 1.5E-3-3.5E-3 in three members of the Miocene-Pleistocene Arroyo Ojito Formation of the Santa Fe Group. Rock magnetic measurements and petrography indicate that the amount of detrital magnetite and its variable oxidation to maghemite and hematite within the Santa Fe Group sediments are the predominant controls of their magnetic property variations. Magnetic susceptibility increases progressively with sediment grain size within the members of the Arroyo Ojito Formation (deposited in fluvial environments) but within members of the Zia Formation (deposited in mostly eolian environments) reaches highest values in fine to medium sands. Partial oxidation of detrital magnetite is spatially associated with calcite cementation in the Santa Fe Group. Both oxidation and cementation probably reflect past flow of groundwater through permeable zones. Magnetic models for geologic cross sections that incorporate mean magnetic susceptibilities for the different stratigraphic units mimic the aeromagnetic profiles across the San Ysidro fault and demonstrate that the stratigraphic level of dominant magnetic contrast changes with

  4. Quantification of susceptibility change at high-concentrated SPIO-labeled target by characteristic phase gradient recognition.

    Science.gov (United States)

    Zhu, Haitao; Nie, Binbin; Liu, Hua; Guo, Hua; Demachi, Kazuyuki; Sekino, Masaki; Shan, Baoci

    2016-05-01

    Phase map cross-correlation detection and quantification may produce highlighted signal at superparamagnetic iron oxide nanoparticles, and distinguish them from other hypointensities. The method may quantify susceptibility change by performing least squares analysis between a theoretically generated magnetic field template and an experimentally scanned phase image. Because characteristic phase recognition requires the removal of phase wrap and phase background, additional steps of phase unwrapping and filtering may increase the chance of computing error and enlarge the inconsistence among algorithms. To solve problem, phase gradient cross-correlation and quantification method is developed by recognizing characteristic phase gradient pattern instead of phase image because phase gradient operation inherently includes unwrapping and filtering functions. However, few studies have mentioned the detectable limit of currently used phase gradient calculation algorithms. The limit may lead to an underestimation of large magnetic susceptibility change caused by high-concentrated iron accumulation. In this study, mathematical derivation points out the value of maximum detectable phase gradient calculated by differential chain algorithm in both spatial and Fourier domain. To break through the limit, a modified quantification method is proposed by using unwrapped forward differentiation for phase gradient generation. The method enlarges the detectable range of phase gradient measurement and avoids the underestimation of magnetic susceptibility. Simulation and phantom experiments were used to quantitatively compare different methods. In vivo application performs MRI scanning on nude mice implanted by iron-labeled human cancer cells. Results validate the limit of detectable phase gradient and the consequent susceptibility underestimation. Results also demonstrate the advantage of unwrapped forward differentiation compared with differential chain algorithms for susceptibility

  5. Magnetic and thermodynamic properties of Ising model with borophene structure in a longitudinal magnetic field

    Science.gov (United States)

    Shi, Kaile; Jiang, Wei; Guo, Anbang; Wang, Kai; Wu, Chuang

    2018-06-01

    The magnetic and thermodynamic properties of borophene structure have been studied for the first time by Monte Carlo simulation. Two-dimensional borophene structure consisting of seven hexagonal B36 units is described by Ising model. Each B36 basic unit includes three benzene-like with spin-3/2. The general formula for the borophene structure is given. The numerical results of the magnetization, the magnetic susceptibility, the internal energy and the specific heat are studied with various parameters. The possibility to test the predicted magnetism in experiment are illustrated, for instance, the maximum on the magnetization curve. The multiple hysteresis loops and the magnetization plateaus are sensitive to the ferromagnetic or ferrimagnetic exchange coupling in borophene structure. The results show the borophene structure could have applications in spintronics, which deserves further studies in experiments.

  6. Unusual magnetic properties of UGa{sub 3} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kaczorowski, D.; Klamut, P.W.; Czopnik, A.; Jezowski, A. [Polska Akademia Nauk, Wroclaw (Poland). Inst. Niskich Temperatur i Badan Strukturalnych

    1998-01-01

    The magnetic behaviour of single-crystalline UGa{sub 3} has been studied by means of DC- and AC-magnetic susceptibility and thermal conductivity measurements. As many as three pronounced singularities have been found in both, the {chi}(T) and {kappa}(T) variations. The features at T{sub N} = 65 K are associated with an antiferromagnetic phase transition while those at T{sub 1} = 40 K and T{sub 2} = 8 K have an unknown origin. At low temperatures a significant diamagnetic response is observed in {chi}`(T) accompanied by a rapid rise in {chi}{sup ``}(T). This behaviour of the AC-susceptibility is strongly dependent on the frequency of the alternating magnetic field and on the strength of the external steady magnetic field. (orig.) 7 refs.

  7. Probing white-matter microstructure with higher-order diffusion tensors and susceptibility tensor MRI

    Science.gov (United States)

    Liu, Chunlei; Murphy, Nicole E.; Li, Wei

    2012-01-01

    Diffusion MRI has become an invaluable tool for studying white matter microstructure and brain connectivity. The emergence of quantitative susceptibility mapping and susceptibility tensor imaging (STI) has provided another unique tool for assessing the structure of white matter. In the highly ordered white matter structure, diffusion MRI measures hindered water mobility induced by various tissue and cell membranes, while susceptibility sensitizes to the molecular composition and axonal arrangement. Integrating these two methods may produce new insights into the complex physiology of white matter. In this study, we investigated the relationship between diffusion and magnetic susceptibility in the white matter. Experiments were conducted on phantoms and human brains in vivo. Diffusion properties were quantified with the diffusion tensor model and also with the higher order tensor model based on the cumulant expansion. Frequency shift and susceptibility tensor were measured with quantitative susceptibility mapping and susceptibility tensor imaging. These diffusion and susceptibility quantities were compared and correlated in regions of single fiber bundles and regions of multiple fiber orientations. Relationships were established with similarities and differences identified. It is believed that diffusion MRI and susceptibility MRI provide complementary information of the microstructure of white matter. Together, they allow a more complete assessment of healthy and diseased brains. PMID:23507987

  8. Structural, dielectric and magnetic studies of magnetoelectric trirutile Fe{sub 2}TeO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Kaushik, S. D., E-mail: sdkaushik@csr.res.in [UGC-DAE-Consortium for Scientific Research Mumbai Centre, R-5 Shed, BARC, Mumbai-400085 (India); Sahu, B.; Mohapatra, S. R.; Singh, A. K. [Department of Physics and Astronomy, National Institute of Technology, Rourkela-769008, Odisha (India)

    2016-05-23

    We have investigated structural, magnetic and dielectric properties of Fe{sub 2}TeO{sub 6} which is a magnetoelectric antiferromagnet with the trirutile lattice. Rietveld analysis of room temperature X-ray diffraction data shows the phase purity of the sample with tetragonal trirutile structure (space group P4{sub 2}/mnm). The DC susceptibility measurement performed on polycrystalline powders exhibits antiferromagnetic ordering below transition temperature ~ 210K. The employment of Curie-Weiss law to inverse magnetic susceptibility only in the temperature range 350-260 K indicates the magnetic ordering starts developing before the transition temperature. The temperature dependent dielectric measurements show an intrinsic behavior of dielectric constant below 150 K while a continuous increase in dielectric constant with temperature above 150 K may be attributed to a small increase in electrical conduction, known commonly in the literatures.

  9. Soil characterization using patterns of magnetic susceptibility versus effective radium concentration

    Directory of Open Access Journals (Sweden)

    F. Girault

    2011-08-01

    Full Text Available Low-field magnetic susceptibility χm and effective radium concentration ECRa, obtained from radon emanation, have been measured in the laboratory with 129 soil samples from Nepal. Samples along horizontal profiles in slope debris or terrace scarps showed rather homogeneous values of both χm and ECRa. One sample set, collected vertically on a lateritic terrace scarp, had homogeneous values of ECRa while χm increased by a factor of 1 to 10 for residual soils and topsoils. However, for a set of samples collected on three imbricated river terraces, values of ECRa, homogeneous over a given terrace, displayed a gradual increase from younger to older terraces. By contrast, χm showed more homogeneous mean values over the three terraces, with a larger dispersion, however, for the younger one. Similarly, Kathmandu sediments exhibited a large increase in ECRa from sand to clay layers, while χm increased moderately. The combination of χm and ECRa, thus, provides a novel tool to characterize quantitatively various soil groups and may be of interest to distinguish modes of alteration or deposition histories.

  10. Slow magnetic relaxation in a cobalt magnetic chain.

    Science.gov (United States)

    Yang, Chen-I; Chuang, Po-Hsiang; Lu, Kuang-Lieh

    2011-04-21

    A homospin ladder-like chain, [Co(Hdhq)(OAc)](n) (1; H(2)dhq = 2,3-dihydroxyquinoxaline), shows a single-chain-magnet-like (SCM-like) behavior with the characteristics of frequency dependence of the out-of-phase component in alternating current (ac) magnetic susceptibilities and hysteresis loops. © The Royal Society of Chemistry 2011

  11. Investigation study of geometric dimensions of the magnetic system of the switched-reluctance machine influence on magnetic moment

    Science.gov (United States)

    Petrushin, A.; Shevkunova, A.

    2018-02-01

    The article deals with the investigation concentrated to optimizing the active part of the switched-reluctance motor with the aim of increasing the value of the average electromagnetic torque. Susceptibility of the average value of the electromagnetic torque to changes of the geometric dimensions of the magnetic system found in the optimization process was set.

  12. The universal relation between thermopower and magnetic susceptibility for a charge ordered manganite: Bi1-xSrxMnO3 (0.5≤x≤0.8)

    International Nuclear Information System (INIS)

    Kim, Byung Hoon; Kim, Jun Sung; Park, Tae Hoi; Park, Seung Joo; Kim, Kyung Hyun; Kim, Bog G; Park, Yung Woo

    2007-01-01

    The relation between the thermoelectric power (S) and magnetic susceptibility (χ) for Bi 1-x Sr x MnO 3 (0.5≤x≤0.8) has been established empirically. A simple linear equation for the relation between the two transport coefficients is deduced from the experimental data. From this relation, we extract the Peltier heat and S for this material. They are composed of two terms: one has a magnetic origin and the other originates from the configuration entropy. The universality of this relation is found by applying the relation to other magnetically interacting systems including colossal magnetoresistance materials and high T C cuprate

  13. Genetic architecture for susceptibility to gout in the KARE cohort study.

    Science.gov (United States)

    Shin, Jimin; Kim, Younyoung; Kong, Minyoung; Lee, Chaeyoung

    2012-06-01

    This study aimed to identify functional associations of cis-regulatory regions with gout susceptibility using data resulted from a genome-wide association study (GWAS), and to show a genetic architecture for gout with interaction effects among genes within each of the identified functions. The GWAS was conducted with 8314 control subjects and 520 patients with gout in the Korea Association REsource cohort. However, genetic associations with any individual nucleotide variants were not discovered by Bonferroni multiple testing in the GWAS (P>1.42 × 10(-7)). Genomic regions enrichment analysis was employed to identify functional associations of cis-regulatory regions. This analysis revealed several biological processes associated with gout susceptibility, and they were quite different from those with serum uric acid level. Epistasis for susceptibility to gout was estimated using entropy decomposition with selected genes within each biological process identified by the genomic regions enrichment analysis. Some epistases among nucleotide sequence variants for gout susceptibility were found to be larger than their individual effects. This study provided the first evidence that genetic factors for gout susceptibility greatly differed from those for serum uric acid level, which may suggest that research endeavors for identifying genetic factors for gout susceptibility should not be heavily dependent on pathogenesis of uric acid. Interaction effects between genes should be examined to explain a large portion of phenotypic variability for gout susceptibility.

  14. Aspects of the magnetism of ferrous chloride

    International Nuclear Information System (INIS)

    Carrara, P.

    1968-01-01

    This work is a critical review of the existing work on ferrous chloride and presents, as well, a number of new experimental results. First, a careful analysis of the level structure of ferrous ions in the crystalline field shows that the crystalline anisotropy is of the same order of magnitude as the exchange interactions, a feature which gives rise to some particular effects, such as an upward curvature of the magnetization curve at 0 K in a perpendicular magnetic field. Further, the very low temperature (T > 0.4 K) thermal variation of both the specific heat and magnetic susceptibility evidences a magnetic component in elementary excitations. This result suggests the presence of a large magneto-elastic coupling. Finally, an experimental study of the H-T phase diagram near T N and of the critical behaviour of the specific heat and parallel susceptibility was performed. (author) [fr

  15. The effect of colloidal stabilization upon ferrimagnetic resonance in magnetic fluids in the presence of a polarizing magnetic field

    CERN Document Server

    Fannin, P C; Socoliuc, V; Istratuca, G M; Giannitsis, A T

    2003-01-01

    The complex magnetic susceptibility of two magnetic fluids, with different degrees of colloidal stabilization, has been measured over the frequency range 100 MHz to 6 GHz. The colloidal stabilization of the magnetic fluids has been investigated using magneto-optical measurements. Based on complex magnetic susceptibility measurements, chi(omega) chi'(omega)-i chi''(omega), the dependence of the maximum absorption frequency at resonance, f sub m sub a sub x , and of line width, DELTA f, on an external magnetic polarizing field, H, over the range 0-1.45 kOe, has been examined for both magnetic fluids. The experimental results have been interpreted in terms of magnetic interparticle interactions and particle agglomeration.

  16. In vitro studies of magnetically enhanced transfection in COS-7 cells

    International Nuclear Information System (INIS)

    Ang, D.; Tay, C.Y.; Tan, L.P.; Preiser, P.R.; Ramanujan, R.V.

    2011-01-01

    In the magnetically enhanced gene delivery technique, DNA complexed with polymer coated aggregated magnetic nanoparticles (AMNPs) is used for effecting transfection. The aim of this study is to examine the relationship between transfection efficiency and the physical characteristics of the polymer coated AMNPs. In vitro studies of transfection efficiency in COS-7 cells were carried out using pEGFP-N1 and pMIR-REPORT complexed polyethylenimine (PEI) coated iron oxide magnetic nanoparticles. PEI coated AMNPs (PEI-AMNPs) with average individual particle diameters in the range of 8 nm to 30 nm were studied and characterized by transmission electron microscopy, vibrating sample magnetometry, X-ray diffractometry, thermal gravimetric analysis and photon correlation spectroscopy methods. PEI-A8MNP and PEI-A30MNP yielded higher transfection efficiency compared to commercial polyMAG particles as well as PEI of equivalent molar ratio of nitrogen/phosphorous (N/P ratio). The transfection efficiency was related to the physical characteristics of the PEI-AMNPs and its complexes: transfection efficiency was strongly positively correlated with saturation magnetization (Ms) and susceptibility (χ), strongly negatively correlated with N/P ratio, moderately positively correlated to zeta potential and moderately negatively correlated to hydrodynamic diameter of the complex. PEI-A8MNP and PEI-A30MNP possessing higher Ms, χ, lower N/P ratio and smaller complex size exhibited higher transfection efficiency compared to PEI-A16MNP which have weaker magnetic properties, higher N/P ratio and larger complex size. We have demonstrated that optimization of the physical properties of PEI-AMNPs is needed to maximize transfection efficiency. - Research highlights: →The transfection efficiency in magnetically enhanced gene delivery was studied. →Transfection efficiency was strongly positively correlated to magnetic properties. →Transfection efficiency was strongly negatively correlated with

  17. Complex magnetic behaviour and evidence of a superspin glass state in the binary intermetallic compound Er5Pd2

    Science.gov (United States)

    Sharma, Mohit K.; Yadav, Kavita; Mukherjee, K.

    2018-05-01

    The binary intermetallic compound Er5Pd2 has been investigated using dc and ac magnetic susceptibilities, magnetic memory effect, isothermal magnetization, non-linear dc susceptibility, heat capacity and magnetocaloric effect studies. Interestingly, even though the compound does not show geometrical frustration it undergoes glassy magnetic phase transition below 17.2 K. Investigation of dc magnetization and heat capacity data divulged absence of long-ranged magnetic ordering. Through the magnetic memory effect, time dependent magnetization and ac susceptibility studies it was revealed that the compound undergoes glass-like freezing below 17.2 K. Analysis of frequency dependence of this transition temperature through scaling and Arrhenius law; along with the Mydosh parameter indicate, that the dynamics in Er5Pd2 are due to the presence of strongly interacting superspins rather than individual spins. This phase transition was further investigated by non-linear dc susceptibility and was characterized by static critical exponents γ and δ. Our results indicate that this compound shows the signature of superspin glass at low temperature. Additionally, both conventional and inverse magnetocaloric effect was observed with a large value of magnetic entropy change and relative cooling power. Our results suggest that Er5Pd2 can be classified as a superspin glass system with large magnetocaloric effect.

  18. Monte Carlo study of magnetic nanoparticles adsorbed on halloysite Al2Si2O5(OH) 4 nanotubes

    Science.gov (United States)

    Sotnikov, O. M.; Mazurenko, V. V.; Katanin, A. A.

    2017-12-01

    We study properties of magnetic nanoparticles adsorbed on the halloysite surface. For that a distinct magnetic Hamiltonian with a random distribution of spins on a cylindrical surface was solved by using a nonequilibrium Monte Carlo method. The parameters for our simulations, the anisotropy constant, nanoparticle size distribution, saturated magnetization, and geometrical characteristics of the halloysite template, were taken from recent experiments. We calculate the hysteresis loops and temperature dependence of the zero-field-cooling (ZFC) susceptibility, the maximum of which determines the blocking temperature. It is shown that the dipole-dipole interaction between nanoparticles moderately increases the blocking temperature and weakly increases the coercive force. The obtained hysteresis loops (e.g., the value of the coercive force) for Ni nanoparticles are in reasonable agreement with the experimental data. We also discuss the sensitivity of the hysteresis loops and ZFC susceptibilities to the change in anisotropy and dipole-dipole interaction, as well as the 3 d -shell occupation of the metallic nanoparticles; in particular we predict larger coercive force for Fe than for Ni nanoparticles.

  19. 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.

  20. Measurement of susceptibility artifacts with histogram-based reference value on magnetic resonance images according to standard ASTM F2119.

    Science.gov (United States)

    Heinrich, Andreas; Teichgräber, Ulf K; Güttler, Felix V

    2015-12-01

    The standard ASTM F2119 describes a test method for measuring the size of a susceptibility artifact based on the example of a passive implant. A pixel in an image is considered to be a part of an image artifact if the intensity is changed by at least 30% in the presence of a test object, compared to a reference image in which the test object is absent (reference value). The aim of this paper is to simplify and accelerate the test method using a histogram-based reference value. Four test objects were scanned parallel and perpendicular to the main magnetic field, and the largest susceptibility artifacts were measured using two methods of reference value determination (reference image-based and histogram-based reference value). The results between both methods were compared using the Mann-Whitney U-test. The difference between both reference values was 42.35 ± 23.66. The difference of artifact size was 0.64 ± 0.69 mm. The artifact sizes of both methods did not show significant differences; the p-value of the Mann-Whitney U-test was between 0.710 and 0.521. A standard-conform method for a rapid, objective, and reproducible evaluation of susceptibility artifacts could be implemented. The result of the histogram-based method does not significantly differ from the ASTM-conform method.

  1. Electron magnetic resonance study of monovalent Na doping in Pr0.6Sr0.4−xNaxMnO3 manganites

    International Nuclear Information System (INIS)

    Thaljaoui, Rachid; Boujelben, Wahiba; Pękała, Marek; Szydłowska, Jadwiga; Cheikhrouhou, Abdelwaheb

    2012-01-01

    Highlights: ► New monovalent doped manganites Pr 0.6 Sr 0.4−x Na x MnO 3 (x = 0, 0.05). ► Comparison of electron magnetic resonance spectra in ferro- and paramagnetic phases. ► Double exchange interactions weakened by Na doping as indicated by activation energy. ► Magnetic susceptibility derived from resonance intensity obeys Curie–Weiss law. - Abstract: Effect of monovalent Na doping on the magnetic properties is studied in Pr 0.6 Sr 0.4−x Na x MnO 3 system (x = 0, 0.05) using X-band electron magnetic resonance and magnetization measurements. Temperature variation of magnetic resonance spectra of doped and undoped manganites is analyzed for paramagnetic and ferromagnetic states and compared to similar systems. In paramagnetic phase the magnetic susceptibility proportional to resonance signal intensity is found to obey the Curie–Weiss law. The effective magnetic moment becomes smaller in doped manganite. The paramagnetic Curie temperature derived from signal intensity equals to 312 and 306 K for the undoped and doped manganites, respectively, and is close to values obtained from magnetization variation in paramagnetic phase. The activation energy determined using the adiabatic small polaron hopping model is higher for the undoped than the doped manganite, which proves that the Na doping slightly reduces the Mn 3+ /Mn 4+ double exchange interactions.

  2. Original Paper Multicenter study on antibiotic susceptibility ...

    African Journals Online (AJOL)

    Multicenter study on antibiotic susceptibility/resistance trends in the western region of Cameroon ... antibiotic era, IDs used to be serious threats because of lack or insufficient ...... antimicrobial use in livestock; AMR. Control., 116-122. Vandini ...

  3. Magnetic and Geochemical Properties of Andic Soils from the Massif Central, France

    Science.gov (United States)

    Grison, H.; Petrovsky, E.; Dlouha, S.; Kapicka, A.

    2014-12-01

    Ferrimagnetic iron oxides are the key magnetic minerals responsible for enhancement of the magnetic susceptibility in soils. Soils with andic properties contain high amount of Fe-oxides, but only few attempts were made to characterize these soils using magnetic methods. Magnetic susceptibility is in particular suitable for its sensitivity and fast measurement; the presence of Fe-oxides can be easily identified directly in the field. The aim of our study is to describe main magnetic and geochemical properties of soils rich in Fe oxides derived from strongly magnetic volcanic basement. The studied sites are located at the basalt parent rock formed during Pleistocene, Pliocene and Miocene. Investigated soils are exposed to the mountainous climate with the perudic soil moisture regime and cryic temperature soil regime. Seven basalt soil profiles with typical andic properties were analyzed down to parent rock by a set of magnetic and geochemical methods. The magnetic susceptibility was measured in situ and in laboratory using the Bartington MS2D and AGICO MFK1. Its temperature dependence was measured in order to assess phase transformations of magnetic minerals using the KLY4. Magnetic data were completed by the hysteresis, IRM and DCD measurements using ADE EV9 VSM. Geochemical data include soil reaction (pH), organic carbon, cations exchange capacity, and extractable iron and aluminium in the soil extracted by a dithionite-citrate, acid-ammonium oxalate and a pyrophosphate solution. Scanning electron microscopy was done for top/sub-soil and rock samples. Geochemical soil properties reflecting iron oxide stability correlate well with mass-specific magnetic susceptibility. Well pronounced relationship was observed between magnetic grain size, precipitation and soil pH, second group is reflecting concentration of feri-magnetic particles and age of parent rock, and the third group reflects degree of weathering and the thermomagnetic indices expressing changes in magneto

  4. Magnetic characteristics of industrial dust from different sources of emission: A case study of Poland

    Czech Academy of Sciences Publication Activity Database

    Szuszkiewicz, M.; Magiera, T.; Kapička, Aleš; Petrovský, Eduard; Grison, Hana; Goluchowska, B.

    2015-01-01

    Roč. 116, May (2015), s. 84-92 ISSN 0926-9851 R&D Projects: GA ČR GAP210/10/0554; GA ČR GA13-10775S Institutional support: RVO:67985530 Keywords : magnetic susceptibility * hysteresis parameters * industrial dusts * technogenic magnetic particles * iron oxides Subject RIV: DI - Air Pollution ; Quality Impact factor: 1.355, year: 2015

  5. Mapping of soil erosion and redistribution on two agricultural areas in Czech Republic by using of magnetic parameters.

    Science.gov (United States)

    Kapicka, Ales; Stejskalova, Sarka; Grison, Hana; Petrovsky, Eduard; Jaksik, Ondrej; Kodesova, Radka

    2015-04-01

    Soil erosion is one of the major concerns in sustainability of agricultural systems in different areas. Therefore there is a need to develop suitable innovative indirect methods of soil survey. One of this methods is based on well established differentiation in magnetic signature with depth in soil profile. Magnetic method can be applied in the field as well as in the laboratory on collected soil samples. The aim of this study is to evaluate suitability of magnetic method to assess soil degradation and construct maps of cumulative soil loss due to erosion at two morphologically diverse areas with different soil types. Dominant soil unit in the first locality (Brumovice) is chernozem, which is gradually degraded on slopes to regosols. In the second site (Vidim), the dominant soil unit is luvisol, gradualy transformed to regosol due to erosion. Field measurements of magnetic susceptibility were carried out on regular grid, resulting in 101 data points in Brumovice and 65 in Vidim locality. Mass specific magnetic susceptibility χ and its frequency dependence χFD was used to estimate the significance of SP ferrimagnetic particles of pedogenic origin in top soil horizons. Strong correlation was found between the volume magnetic susceptibility (field measurement) and mass- specific magnetic susceptibility measured in the laboratory (Kapicka et al 2013). Values of magnetic susceptibility are spatially distributed depending on terrain position. Higher values were measured at the flat parts (where the original topsoil horizon remained). The lowest values magnetic susceptibility were obtained on the steep valley sides. Here the original topsoil was eroded and mixed by tillage with the soil substrate (loess). Positive correlation between the organic carbon content and volume magnetic susceptibility (R2= 0.89) was found for chernozem area. The differences between the values of susceptibility in the undisturbed soil profile and the magnetic signal after uniform mixing of the

  6. Strain indicators and magnetic fabric in intraplate fault zones: Case study of Daroca thrust, Iberian Chain, Spain

    Science.gov (United States)

    Casas-Sainz, A. M.; Gil-Imaz, A.; Simón, J. L.; Izquierdo-Llavall, E.; Aldega, L.; Román-Berdiel, T.; Osácar, M. C.; Pueyo-Anchuela, Ó.; Ansón, M.; García-Lasanta, C.; Corrado, S.; Invernizzi, C.; Caricchi, C.

    2018-04-01

    Anisotropy of magnetic susceptibility (AMS) has been applied to the study of shallow fault zones, although interpretation of the results requires establishing clear relationships between petrofabric and magnetic features, magnetic behaviour of fault rocks, and an extensive knowledge of P-T conditions. In this work, we demonstrate that magnetic methods can be applied to the study of heterogeneous fault zones, provided that a series of requisites are met. A major fault zone within the Iberian plate (Daroca thrust), showing transpressional movements during Cenozoic time was chosen for this purpose, because of the exceptional outcrops of fault gouge and microbreccia and its relevance within the context of the northeastern Iberian Plate. Magnetic fabrics were analysed and the results were compared with foliation and S-C structures measured within the fault zone. Clay mineral assemblages suggest maximum burial depths shallower than 2 km (kinematic indicators are consistent with a reverse movement for most of the fault zone.

  7. Pre-excavation studies of prehistoric cave sites by magnetic prospecting

    Science.gov (United States)

    Itkis., Sonia; Matskevich, Zinovii; Meshveliani, Tengiz

    2014-05-01

    Detailed magnetic survey was performed for caves study in Israel (1995-1996) within the framework of the Beit Shemesh Regional Project (Judean Shephelah). The experience accumulated in Israel we applied later (2010) in two Georgian prehistoric cave sites: Cherula and Kotias-Klde. The magnetic method is based on the contrast in magnetic properties between a target object (e.g., buried archaeological feature) and the host medium (i.e, the surrounding bedrock and soil). The feasibility of the magnetic method for cave revealing was evaluated by magnetic susceptibility (κ) measurements of surrounding soil and rocks, and archaeological features: stones making up the walls, ceramic fragments and cave fill. According to data obtained, the κ of soil within caves (cave fill) is higher than that of surrounding soil. The enhancement of cave fill κ occurs because processes associated with human habitation: repeated heating and accumulation of organic debris. Both these processes provide good conditions for the conversion of the iron oxide found within the soil to a strongly ferromagnetic form (Mullins, 1977; Maher, 1986; Dalan and Banerjee, 1998, Itkis and Eppelbaum, 1999; Itkis, 2003) The presence of highly magnetic ceramics in caves also enhances magnetic contrast between practically non-magnetic bed rock (chalk in Ramat Beit Shemesh Site (Israel) and limestone (Georgian sites) and the cave fill, increasing the potential of the magnetic method to reveal caves (Itkis, 2011). Based on magnetic survey results, an excavation revealed a cave with a large amount of well preserved pottery and finds typical of the Early Bronze Age. Both studied cave sites in Georgia were located in Chiatura region of Imeretia province. Cherula site is a karstic rockshelter with a single chamber, ca 100 sq. m. The site was briefly tested in 1970s'. The area excavated in 2010 went to the depth of 60 cm below the present day surface; the limestone bedrock was not reached. The excavation revealed

  8. Can Dynamic Susceptibility Contrast Magnetic Resonance Imaging Replace Single-Photon Emission Computed Tomography in the Diagnosis of Patients with Alzheimer's Disease? A Pilot Study

    Energy Technology Data Exchange (ETDEWEB)

    Cavallin, L.; Danielsson, R.; Oeksengard, A.R.; Wahlund, L.O.; Julin, P.; Frank, A.; Engman, E.L.; Svensson, L.; Kristoffersen Wiberg, M. [Karolinska Univ. Hospital, Stockholm (Sweden). Div. of Radiology

    2006-11-15

    Purpose: To compare single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI) in a cohort of patients examined for suspected dementia, including patients with no objective cognitive impairment (control group), mild cognitive impairment (MCI), and Alzheimer's disease (AD). Material and Methods: Twenty-four patients, eight with AD, 10 with MCI, and six controls were investigated with SPECT using {sup 99m}Tc-hexamethylpropyleneamine oxime (HMPAO) and dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) with gadobutrol. Three observers performed a visual interpretation of the SPECT and MR images using a four-point visual scale. Results: SPECT was superior to DSC-MRI in differentiating normal from pathological. All three observers showed statistically significant results in discriminating between the control group, AD, and MCI by SPECT, with a P value of 0.0006, 0.04, and 0.01 for each observer. The statistical results were not significant for MR (P values 0.8, 0.1, and 0.2, respectively). Conclusion: DSC-MRI could not replace SPECT in the diagnosis of patients with Alzheimer's disease. Several patient- and method-related improvements should be made before this method can be recommended for clinical practice.

  9. 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.

  10. Van Vleck temperature independent susceptibilities in the rare earth double nitrates

    International Nuclear Information System (INIS)

    Commander, R.J.; Finn, C.B.P.

    1978-01-01

    Measurements of the magnetic susceptibilities between 4.2 and 1.1 K of the rare earth zinc nitrates are reported. It is shown that the results for the Van Vleck temperature independent susceptibilities for cerium magnesium nitrate and cerium zinc nitrate are consistent with the published low lying level schemes for these two salts. (author)

  11. Magnetic and superconducting properties of Ir-doped EuFe2As2

    International Nuclear Information System (INIS)

    B Paramanik, U; Hossain, Z; L Paulose, P; Ramakrishnan, S; K Nigam, A; Geibel, C

    2014-01-01

    The magnetic and superconducting properties of 14% Ir-doped EuFe 2 As 2 are studied by means of dc and ac magnetic susceptibilities, electrical resistivity, specific heat and 151 Eu and 57 Fe Mössbauer spectroscopy (MS) measurements. Doping of Ir in EuFe 2 As 2 suppresses the Fe spin density wave transition and in turn gives rise to high temperature superconductivity below 22.5 K with a reentrant feature at lower temperature. Magnetization and 151 Eu Mössbauer data indicate that the Eu 2+ spins order magnetically below 18 K. 57 Fe MS studies show a line broadening in the absorption spectra below 18 K due to transferred hyperfine field from the magnetically ordered Eu sublattices. A pronounced λ-shape peak in the specific heat supports a second-order phase transition of Eu 2+ magnetic ordering with a strong ferromagnetic component, as confirmed by the magnetic field dependences of the transition. For a single crystal, the in-plane resistivity (ρ ab ) and out-of-plane susceptibility (χ c ) show superconducting transitions with zero resistance and diamagnetism, respectively. But the in-plane susceptibility (χ ab ) does not show any diamagnetic shielding against external fields. The observed non-zero resistance in the temperature range 10–17.5 K, below the superconducting transition temperature, suggests the possible existence of a spontaneous vortex state in this superconductor. (papers)

  12. Magnetic properties of Gd5(Si1.5Ge2.5) near the temperature and magnetic field induced first order phase transition

    International Nuclear Information System (INIS)

    Levin, E.M.; Gschneidner, K.A.; Pecharsky, V.K.

    2001-01-01

    The temperature (from 5 to 300 K) and DC magnetic field (from 0 to 90 kOe) dependencies of the DC magnetization and magnetic susceptibility, and the temperature (from 5 to 350 K) dependency of the AC magnetic susceptibility of Gd 5 (Si 1.5 Ge 2.5 ) have been studied. The temperature and/or magnetic field induced magnetic phase transition in Gd 5 (Si 1.5 Ge 2.5 ) is a first order ferromagnet-paramagnet transition. The temperature of the magnetic transition in low AC magnetic field is 206 and 217 K for cooling and heating, respectively. The DC magnetic field increases the transition temperature by ∼0.36 K/kOe indicating that the paramagnetic phase can be reversibly transformed into the ferromagnetic phase. When the magnetic field is removed, the ferromagnetic phase transforms into the paramagnetic phase showing a large remanence-free hysteresis. The magnetic phase diagram based on the isothermal magnetic field dependence of the DC magnetization at various temperatures for Gd 5 (Si 1.5 Ge 2.5 ) is proposed. The magnetic field dependence of the magnetization in the vicinity of the first order phase transition shows evidence for the formation of a magnetically heterogeneous system in the volume of Gd 5 (Si 1.5 Ge 2.5 ) specimen where the magnetically ordered (ferromagnetic) and disordered (paramagnetic) phases co-exist

  13. Joint eigenvector estimation from mutually anisotropic tensors improves susceptibility tensor imaging of the brain, kidney, and heart.

    Science.gov (United States)

    Dibb, Russell; Liu, Chunlei

    2017-06-01

    To develop a susceptibility-based MRI technique for probing microstructure and fiber architecture of magnetically anisotropic tissues-such as central nervous system white matter, renal tubules, and myocardial fibers-in three dimensions using susceptibility tensor imaging (STI) tools. STI can probe tissue microstructure, but is limited by reconstruction artifacts because of absent phase information outside the tissue and noise. STI accuracy may be improved by estimating a joint eigenvector from mutually anisotropic susceptibility and relaxation tensors. Gradient-recalled echo image data were simulated using a numerical phantom and acquired from the ex vivo mouse brain, kidney, and heart. Susceptibility tensor data were reconstructed using STI, regularized STI, and the proposed algorithm of mutually anisotropic and joint eigenvector STI (MAJESTI). Fiber map and tractography results from each technique were compared with diffusion tensor data. MAJESTI reduced the estimated susceptibility tensor orientation error by 30% in the phantom, 36% in brain white matter, 40% in the inner medulla of the kidney, and 45% in myocardium. This improved the continuity and consistency of susceptibility-based fiber tractography in each tissue. MAJESTI estimation of the susceptibility tensors yields lower orientation errors for susceptibility-based fiber mapping and tractography in the intact brain, kidney, and heart. Magn Reson Med 77:2331-2346, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  14. Ellipsoids (v1.0): 3-D magnetic modelling of ellipsoidal bodies

    Science.gov (United States)

    Takahashi, Diego; Oliveira, Vanderlei C., Jr.

    2017-09-01

    A considerable amount of literature has been published on the magnetic modelling of uniformly magnetized ellipsoids since the second half of the nineteenth century. Ellipsoids have flexibility to represent a wide range of geometrical forms, are the only known bodies which can be uniformly magnetized in the presence of a uniform inducing field and are the only finite bodies for which the self-demagnetization can be treated analytically. This property makes ellipsoids particularly useful for modelling compact orebodies having high susceptibility. In this case, neglecting the self-demagnetization may strongly mislead the interpretation of these bodies by using magnetic methods. A number of previous studies consider that the self-demagnetization can be neglected for the case in which the geological body has an isotropic susceptibility lower than or equal to 0.1 SI. This limiting value, however, seems to be determined empirically and there has been no discussion about how this value was determined. In addition, the geoscientific community lacks an easy-to-use tool to simulate the magnetic field produced by uniformly magnetized ellipsoids. Here, we present an integrated review of the magnetic modelling of arbitrarily oriented triaxial, prolate and oblate ellipsoids. Our review includes ellipsoids with both induced and remanent magnetization, as well as with isotropic or anisotropic susceptibility. We also discuss the ambiguity between confocal ellipsoids with the same magnetic moment and propose a way of determining the isotropic susceptibility above which the self-demagnetization must be taken into consideration. Tests with synthetic data validate our approach. Finally, we provide a set of routines to model the magnetic field produced by ellipsoids. The routines are written in Python language as part of the Fatiando a Terra, which is an open-source library for modelling and inversion in geophysics.

  15. Ellipsoids (v1.0: 3-D magnetic modelling of ellipsoidal bodies

    Directory of Open Access Journals (Sweden)

    D. Takahashi

    2017-09-01

    Full Text Available A considerable amount of literature has been published on the magnetic modelling of uniformly magnetized ellipsoids since the second half of the nineteenth century. Ellipsoids have flexibility to represent a wide range of geometrical forms, are the only known bodies which can be uniformly magnetized in the presence of a uniform inducing field and are the only finite bodies for which the self-demagnetization can be treated analytically. This property makes ellipsoids particularly useful for modelling compact orebodies having high susceptibility. In this case, neglecting the self-demagnetization may strongly mislead the interpretation of these bodies by using magnetic methods. A number of previous studies consider that the self-demagnetization can be neglected for the case in which the geological body has an isotropic susceptibility lower than or equal to 0.1 SI. This limiting value, however, seems to be determined empirically and there has been no discussion about how this value was determined. In addition, the geoscientific community lacks an easy-to-use tool to simulate the magnetic field produced by uniformly magnetized ellipsoids. Here, we present an integrated review of the magnetic modelling of arbitrarily oriented triaxial, prolate and oblate ellipsoids. Our review includes ellipsoids with both induced and remanent magnetization, as well as with isotropic or anisotropic susceptibility. We also discuss the ambiguity between confocal ellipsoids with the same magnetic moment and propose a way of determining the isotropic susceptibility above which the self-demagnetization must be taken into consideration. Tests with synthetic data validate our approach. Finally, we provide a set of routines to model the magnetic field produced by ellipsoids. The routines are written in Python language as part of the Fatiando a Terra, which is an open-source library for modelling and inversion in geophysics.

  16. Study of magnetic structure of neptunium compounds: Np As, Np Sb, Np Se et Np Ru2 Si2

    International Nuclear Information System (INIS)

    Bonnisseau, D.

    1987-11-01

    Magnetic behavior and localization of 5f electrons in actinide compounds is studied experimentally by Moessbauer spectroscopy and neutron diffraction. Binary actinide compounds with a NaCl structure are examined and properties of U, Pu and Np monopnictides and monochalcogenides are recalled. Results of neutron diffraction by NpAs and NpSb are discussed and results of magnetic susceptibility, magnetization, Moessbauer spectroscopy and neutron diffraction measurements on NpSe and NpTe are presented. Magnetic properties of NpRu 2 Si 2 are also presented. Heavy fermion system electronic and magnetic properties are described and theory is discussed. Electronic and magnetic properties of CeCu 2 Si 2 , CeRu 2 Si 2 and URu 2 Si 2 are compared to NpRu 2 Si 2 which has the same crystal structure [fr

  17. Magnetization of Paraffin-Based Magnetic Nanocolloids

    Science.gov (United States)

    Dikanskii, Yu. I.; Ispiryan, A. G.; Kunikin, S. A.; Radionov, A. V.

    2018-01-01

    Using paraffin-based magnetic nanocolloids as an example, the reasons for maxima in the temperature dependence of the magnetic susceptibility of magnetic colloids have been discussed. The behavior of these dependences in a wide temperature interval has been analyzed for colloids in solid and liquid states. It has been concluded that the maximum observed at the melting point of paraffin can be attributed to freezing Brownian degrees of freedom in magnetite coarse particles, the magnetic moment of which is intimately related to the solid matrix. The second main maximum, which arises in the solid state, is explained by the superparamagnetic-magnetically hard transition of most fine particles at lower temperatures. It has been noted that the flatness of this maximum results from the polydispersity of the magnetic nanoparticle ensemble.

  18. Preliminary Geochemical and Rock Magnetic Study of a Stalagmite From Quintana Roo, Northeastern Yucatan Peninsula

    Science.gov (United States)

    Urrutia-Fucugauchi, J.; Perez-Cruz, L.; Zhao, X.; Rebolledo-Vieyra, M.; Rodriguez, A.

    2012-04-01

    We present the preliminary results of geochemical, stable isotopes and rock magnetic studies of a stalagmite from a cave in eastern Quintana Roo, northern Yucatan peninsula. In the past years, there has been increased interest in understanding the paleoclimatic and paleoenvironmental evolution of the Yucatan peninsula and northern Central America, investigating the relationships between climate variations and the development of the Maya civilization. In particular, the variations in regional precipitation and occurrence of several drought periods, which might have been related to the collapse of the Classic Maya period. Stable isotope data on speleothems from different sites in Yucatan and Central America have provided evidence on changes in precipitation, which have affected the Maya region. The stalagmite is ~47 cm long and about 4-5 cm wide at its base. It was collected from the Hilariós Well cave in Tulum, Quintana Roo. Magnetic susceptibility and geochemical analyses have been completed as part of the initial characterization of the stalagmite, with measurements taken every centimeter. Geochemical analyses have been carried out for x-ray fluorescence, with a Niton XRF analyzer. Magnetic susceptibility was determined with a Bartington MS2 instrument using the high resolution surface probe. Additional rock magnetic analyses include magnetic hysteresis loops and isothermal remanent magnetization (IRM) acquisition, and saturation IRM demagnetization, which have been measured with a MicroMag instrument. Hysteresis loops are diamagnetic, with small varying low-coercivity ferromagnetic components. The elemental compositions of major oxides and trace elements vary with depth. Calcium is the major element and displays a pattern of small amplitude fluctuations with a trend to lower values at the bottom, which are also shown in other elements such as barium. Silica and elements such as titanium and strontium are positively correlated and show an apparent cyclic pattern

  19. Mineral transformations and magnetic properties: example of an uranium rich front of oxido-reduction

    International Nuclear Information System (INIS)

    Mergaux, O.; Samama, J.C.

    1987-01-01

    In sedimentary environments, the mineral associations and the associated magnetic properties may be ascribed to superimposed processes of sedimentation, diagenesis and epigenesis. In the case of uranium sandstone deposits, the epigenetic processes of oxido-reduction are responsible for both concentration in uranium and specific mineral transformations which are related to variations in the magnetic properties of the rocks. These variations are illustrated by the Treville deposit (Southwestern France), where uranium rich bodies have developed within the Tertiary sandstones. The unaltered sandstones are characterized by a low magnetic susceptibility (scarcity of ferrimagnetic species but abundance of paramagnetic species). The siderite rich facies forming part of the front does not display any significant change in the mean magnetic susceptibility whilst the uranium-pyrite facies which belongs to the same front indicates a much lower susceptibility. The mean susceptibility facies resulting from pyrite and siderite oxidation remains unchanged. The facies of alteration of the iron rich silicates is responsible for higher susceptibility. The comparison between measured susceptibility and computed susceptibility helps in interpreting the role of the various species in the overall susceptibility of the rocks. It may also help in restituting the mineral associations from magnetic and chemical logging

  20. Clinical applications of susceptibility weighted MR imaging of the brain - a pictorial review

    International Nuclear Information System (INIS)

    Thomas, Bejoy; Somasundaram, Sivaraman; Thamburaj, Krishnamoorthy; Kesavadas, Chandrasekharan; Kumar Gupta, Arun; Bodhey, Narendra K.; Raman Kapilamoorthy, Tirur

    2008-01-01

    Susceptibility-weighted imaging (SWI) is a novel magnetic resonance (MR) technique that exploits the magnetic susceptibility differences of various tissues, such as blood, iron and calcification. This pictorial review covers many clinical conditions illustrating its usefulness. SWI consists of using both magnitude and phase images from a high-resolution, three-dimensional fully velocity-compensated gradient echo sequence. Phase mask is created from the MR phase images, and multiplying these with the magnitude images increase the conspicuity of the smaller veins and other sources of susceptibility effects, which is depicted using minimal intensity projection (minIP). The phase images are useful in differentiating between diamagnetic and paramagnetic susceptibility effects of calcium and blood, respectively. This unique MR sequence will help in detecting occult low flow vascular lesions, calcification and cerebral microbleed in various pathologic conditions and aids in characterizing tumors and degenerative diseases of the brain. This sequence also can be used to visualize normal brain structures with conspicuity. Susceptibility-weighted imaging is useful in differentiating and characterizing diverse brain pathologies. (orig.)

  1. Size effect on magnetic properties of a nano-graphene bilayer structure: A Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Masrour, R. [Laboratory of Materials, Process, Environment and Quality, Cady Ayyad University, National School of Applied Sciences, Safi (Morocco); Laboratoire de Magnetisme et Physique des Hautes Energies L.M.P.H.E.URAC 12, Universite Mohammed V-Agdal, Faculte des Sciences, B.P. 1014 Rabat (Morocco); Bahmad, L., E-mail: bahmad@fsr.ac.ma [Laboratoire de Magnetisme et Physique des Hautes Energies L.M.P.H.E.URAC 12, Universite Mohammed V-Agdal, Faculte des Sciences, B.P. 1014 Rabat (Morocco); Benyoussef, A. [Laboratoire de Magnetisme et Physique des Hautes Energies L.M.P.H.E.URAC 12, Universite Mohammed V-Agdal, Faculte des Sciences, B.P. 1014 Rabat (Morocco)

    2012-11-15

    In this paper we use the Monte Carlo simulations to investigate the magnetic properties of an Ising ferromagnetic-antiferromagnetic model. The system is based on a nano-graphene structure-like bilayer with two bloc sizes: N=24 and 42 spins. For each size N, the upper layer A is formed with spin -3/2, whereas the lower layer B is composed of spin -5/2. We only consider the first nearest-neighbor interactions between the sites i and j. The magnetic properties are studied, in the absence as well as in the presence of a crystal magnetic field, and an external magnetic field. The increasing temperature and crystal field as well as the inter-layer coupling constant, are also studied for this system sizes N=24 and 42 spins. The zero-field-cooled and the field cooled magnetization behaviors are investigated for different values of external magnetic field and a fixed value of exchange interaction between the two blocs. The magnetizations as well as the magnetic susceptibilities versus the temperature are used in order to obtain blocking temperature. The saturation magnetization and coercive field are also obtained for the two sizes of the studied system. It is found that the blocking temperature decreases on increasing the crystal magnetic field and/or the external magnetic field, for a fixed system size. On the other hand, it is found that the blocking temperature increases on increasing the system size from N=24 to 42 spins, for fixed values of external and the crystal magnetic fields. - Highlights: Black-Right-Pointing-Pointer Magnetic properties of an Ising ferromagnetic-antiferromagnetic bilayer is studied. Black-Right-Pointing-Pointer Monte Carlo simulations are used. Black-Right-Pointing-Pointer Zero-field-cooled (ZFC) and field cooled (FC) magnetization behaviors for nano-graphene are obtained.

  2. Characterization of magnetically enhanced buried soil layer in arid environment

    Science.gov (United States)

    Petrovsky, E.; Grison, H.; Kapicka, A.; Silva, P. F.; Font, E.

    2011-12-01

    Magnetic susceptibility (MS) of soils, reflecting the presence of magnetite/maghemite, can be used in several environmental applications. Magnetic topsoil mapping is often used to outline areas polluted by atmospherically deposited dust. However, in these studies, the magnetically enhanced layer is usually shallow, some 5-6 cm under the surface. In our contribution, we present the case when the magnetic susceptibility is enhanced in deeper soil layers. Investigated soils are mostly sandy soils, from several localities in Portugal, in a zone with arid climate. Sample profiles were collected always in forests or forest stands with pines, cork oaks or eucalyptus trees in two areas: around the city of Sines (on the coast south of Lisbon) and around the city of Abrantes (inland, north-east of Lisbon). Both areas are presumably affected by one major source of pollution - power plant. Surface magnetic susceptibility measurements were performed by Bartington MS2D loop; values vary from 10 to 300 x 10-5 SI units. Vertical distribution of magnetic susceptibility was measured already in situ using the SM400 (ZHInstruments) on profiles about 40cm in length. Mass-specific MS was determined using Bartington MS2B dual frequency meter and Agico MFK1. Nine vertical profiles were selected for detailed analyses including the ARM, IRM and hysteresis measurements. Distinctly enhanced magnetic layers were detected in deeper horizons. This enhancement can be ascribed to several mechanisms. Migration of magnetic particles seems to be probable, as observed in our model experiments with sand columns. In coastal areas, the enhanced layer could be due to tsunami deposits, as described in other areas. Finally, in particular at sites close to power plants, the construction works followed by surface remediation have to be also considered as one of the possible mechanisms.

  3. Characterization of quasi-one-dimensional S=1/2 Heisenberg antiferromagnets Sr2Cu(PO4)2 and Ba2Cu(PO4)2 with magnetic susceptibility, specific heat, and thermal analysis

    International Nuclear Information System (INIS)

    Belik, A.A.; Azuma, M.; Takano, M.

    2004-01-01

    Properties of Sr 2 Cu(PO 4 ) 2 and Ba 2 Cu(PO 4 ) 2 having [Cu(PO 4 ) 2 ] ∞ linear chains in their structures with Cu-O-P-O-Cu linkages were studied by magnetic susceptibility (T=2-400 K, H=100 Oe) and specific heat measurements (T=0.45-21 K). Magnetic susceptibility versus temperature curves, χ(T), showed broad maxima at T M =92 K for Sr 2 Cu(PO 4 ) 2 and T M =82 K for Ba 2 Cu(PO 4 ) 2 characteristic of quasi-one-dimensional systems. The χ(T) data were excellently fitted by the spin susceptibility curve for the uniform S=1/2 chain (plus temperature-independent and Curie-Weiss terms) with g=2.153(4) and J/k B =143.6(2) K for Sr 2 Cu(PO 4 ) 2 and g=2.073(4) and J/k B =132.16(9) K for Ba 2 Cu(PO 4 ) 2 (Hamiltonian H=JΣS i S i+1 ). The similar J/k B values were obtained from the specific heat data. No anomaly was observed on the specific heat from 0.45 to 21 K for both compounds indicating that the temperatures of long-range magnetic ordering, T N , were below 0.45 K. Sr 2 Cu(PO 4 ) 2 and Ba 2 Cu(PO 4 ) 2 are an excellent physical realization of the S=1/2 linear chain Heisenberg antiferromagnet with k B T N /J 2 CuO 3 (k B T N /J∼0.25%) and γ-LiV 2 O 5 (k B T N /J 2 Cu(PO 4 ) 2 and Ba 2 Cu(PO 4 ) 2 were stable in air up to 1280 and 1150 K, respectively

  4. Investigation of polluted alluvial soils by magnetic susceptibility methods: a case study of the Litavka River

    Czech Academy of Sciences Publication Activity Database

    Dlouhá, Šárka; Petrovský, Eduard; Kapička, Aleš; Borůvka, L.; Ash, Ch.; Drábek, O.

    2013-01-01

    Roč. 8, č. 4 (2013), s. 151-157 ISSN 1801-5395 Institutional support: RVO:67985530 Keywords : environmental magnetism * Fluvisols * magnetite/maghemite * risk elements Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.615, year: 2013

  5. Recent advances in anisotropy of magnetic remanence: New software and practical examples

    Czech Academy of Sciences Publication Activity Database

    Chadima, Martin

    -, special issue (2012), s. 59-60 ISSN 1335-2806. [Castle meeting New Trends in Geomagnetism : Paleo, rock and environmental magnetism/13./. 17.06.2012-23.06.2012, Zvolen] Institutional support: RVO:67985831 Keywords : magnetic susceptibility * anisotropy * anisotropy of magnetic susceptibility Subject RIV: DE - Earth Magnetism, Geodesy, Geography http://gauss.savba.sk/GPIweb/conferences/Castle2012/abstrCastle.pdf

  6. Finite-Size Effects in Single Chain Magnets: An Experimental and Theoretical Study

    Science.gov (United States)

    Bogani, L.; Caneschi, A.; Fedi, M.; Gatteschi, D.; Massi, M.; Novak, M. A.; Pini, M. G.; Rettori, A.; Sessoli, R.; Vindigni, A.

    2004-05-01

    The problem of finite-size effects in s=1/2 Ising systems showing slow dynamics of the magnetization is investigated introducing diamagnetic impurities in a Co2+-radical chain. The static magnetic properties have been measured and analyzed considering the peculiarities induced by the ferrimagnetic character of the compound. The dynamic susceptibility shows that an Arrhenius law is observed with the same energy barrier for the pure and the doped compounds while the prefactor decreases, as theoretically predicted. Multiple spin reversal has also been investigated.

  7. Experimental study of the magnetic phase transition in the MnSi itinerant helimagnet

    International Nuclear Information System (INIS)

    Stishov, S. M.; Petrova, A. E.; Khasanov, S.; Panova, G. Kh.; Shikov, A. A.; Lashley, J. C.; Wu, D.; Lograsso, T. A.

    2008-01-01

    Magnetic susceptibility, heat capacity, thermal expansion, and resistivity of a high-quality single crystal of MnSi were carefully studied at ambient pressure. The calculated change in magnetic entropy in the temperature range 0-30 K is less than 0.1R, a low value that emphasizes the itinerant nature of magnetism in MnSi. A linear temperature term dominates the behavior of the thermal expansion coefficient in the range 30-150 K, which correlates to a large enhancement of the linear electronic term in the heat capacity. A surprising similarity between variation of the heat capacity, the thermal expansion coefficient, and the temperature derivative of resistivity through the phase transition in MnSi is observed. Specific forms of the heat capacity, thermal expansion coefficient, and temperature derivative of resistivity at the phase transition to a helical magnetic state near 29 K are interpreted as a combination of sharp first-order features and broad peaks or shallow valleys of yet unknown origin. The appearance of these broad satellites probably hints at a frustrated magnetic state in MnSi slightly above the transition temperature. Present experimental findings bring the current views on the phase diagram of MnSi into question

  8. SCC susceptibility of cold-worked stainless steel with minor element additions

    International Nuclear Information System (INIS)

    Nakano, Junichi; Nemoto, Yoshiyuki; Tsukada, Takashi; Uchimoto, Tetsuya

    2011-01-01

    To examine the effects of minor elements on stress corrosion cracking (SCC) susceptibility of low carbon stainless steels with a work hardened layer, a high purity type 304 stainless steel was fabricated and minor elements, Si, S, P, C or Ti, were added. A work hardened layer was introduced by shaving on the surface of stainless steels. The specimens were exposed to a boiling 42% MgCl 2 solution for 20 h and the number and the length of initiated cracks were examined. SCC susceptibility of the specimen with P was the highest and that of the specimen with C was the lowest in all specimens. By magnetic force microscope examination, a magnetic phase expected to be a martensitic phase was detected near the surface. Since corrosion resistance of martensite is lower than that of austenite, the minor elements additions would affect SCC susceptibility through the amount of the transformed martensite.

  9. Neutron Scattering studies of magnetic molecular magnets

    International Nuclear Information System (INIS)

    Chaboussant, G.

    2009-01-01

    This work deals with inelastic neutron scattering studies of magnetic molecular magnets and focuses on their magnetic properties at low temperature and low energies. Several molecular magnets (Mn 12 , V 15 , Ni 12 , Mn 4 , etc.) are reviewed. Inelastic neutron scattering is shown to be a perfectly suited spectroscopy tool to -a) probe magnetic energy levels in such systems and -b) provide key information to understand the quantum tunnel effect of the magnetization in molecular spin clusters. (author)

  10. Studies on maize inbred lines susceptibility to herbicides

    Directory of Open Access Journals (Sweden)

    Stefanović Lidija

    2010-01-01

    Full Text Available This paper presents the analysis of results obtained during long- term studies on the response of maize inbred lines to herbicides. Under the agroecological conditions of Zemun Polje the response (reaction of maize inbred lines to herbicides of different classes was investigated. Biological tests were performed and some agronomic, morphological, physiological and biochemical parameters were determined when the response of maize inbred lines to herbicides was estimated. The use of active ingredients of herbicides from triazine, acetanilide, thiocarbamate to new chemical groups (sulfonylurea etc., have been resulted in changes in weed suppression and susceptibility of inbred lines. Obtained results show that effects of herbicides on susceptible maize genotypes can be different: they can slowdown the growth and development and affect the plant height; they can also affect the stages of the tassel and ear development and at the end they can reduced grain yield of the tested inbreds. Numerous studies confirmed the existence of differences in susceptibility level of maize genotypes in relation to herbicides. According to gained results the recommendations for growers are made on the possibility of the application of new herbicides in the hybrid seed production.

  11. Anisotropic magnetic properties of Dy{sub 6}Cr{sub 4}Al{sub 43} single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, Arvind, E-mail: arvindmaurya@tifr.res.in; Thamizhavel, A., E-mail: arvindmaurya@tifr.res.in; Dhar, S. K., E-mail: arvindmaurya@tifr.res.in [Department of Condensed Matter Physics and Material Science, Tata Institute of Fundamental Research, Mumbai-400005 (India)

    2014-04-24

    We have studied the anisotropic magnetic behavior of the rare earth intermetallic compound Dy{sub 6}Cr{sub 4}Al{sub 43}. This compound crystallizes in the hexagonal symmetry and orders ferromagnetically at 8.3 K as confirmed by the magnetic susceptibility and heat capacity measurements. A significant anisotropy in the magnetization is observed between the c axis and the ab-plane. The easy axis liesin theab-plane at low temperatures; however it orients itselfalong the c-axis above 170 K as inferred from the susceptibility data.

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

    Czech Academy of Sciences Publication Activity Database

    Hrouda, F.; Chadima, Martin; Ježek, J.; Pokorný, J.

    2017-01-01

    Roč. 208, č. 1 (2017), s. 385-402 ISSN 0956-540X R&D Projects: GA AV ČR IAAX00130801 Institutional support: RVO:67985831 Keywords : magnetic and electrical properties * magnetic fabrics and anisotropy * magnetic mineralogy and petrology * rock and mineral magnetism Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 2.414, year: 2016

  13. Magnetic and magneto-elastic properties of a single crystal of TbB{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Granovsky, S.A.; Amara, M.; Galera, R.M. [Laboratoire Louis Neel, CNRS, BP 166, Grenoble (France); Kunii, S. [Department of Physics, Faculty of Science, Tohoku University, Aramaki, Aoba-ku, Sendai (Japan)

    2001-07-23

    The magnetic and magneto-elastic properties of a single crystal of TbB{sub 6} are studied. In the ordered range metamagnetic behaviours are observed and complex phase diagrams are determined for magnetic fields along fourfold and threefold directions. In the paramagnetic phase the third-order magnetic susceptibilities and the parastriction curves show anisotropic behaviour which could be accounted for by crystalline electric field (CEF) effects. A set of CEF parameters is proposed on the basis of the analysis of the experimental magnetic and quadrupolar susceptibilities. Though non-negligible, the deduced quadrupolar couplings are weak in comparison with those previously determined in PrB{sub 6}. (author)

  14. Risky business: a longitudinal study examining cigarette smoking initiation among susceptible and non-susceptible e-cigarette users in Canada.

    Science.gov (United States)

    Aleyan, Sarah; Cole, Adam; Qian, Wei; Leatherdale, Scott T

    2018-05-26

    Given that many adolescent e-cigarette users are never-smokers, the possibility that e-cigarettes may act as a gateway to future cigarette smoking has been discussed in various studies. Longitudinal data are needed to explore the pathway between e-cigarette and cigarette use, particularly among different risk groups including susceptible and non-susceptible never-smokers. The objective of this study was to examine whether baseline use of e-cigarettes among a sample of never-smoking youth predicted cigarette smoking initiation over a 2-year period. Longitudinal cohort study. 89 high schools across Ontario and Alberta, Canada. A sample of grade 9-11 never-smoking students at baseline (n=9501) who participated in the COMPASS study over 2 years. Participants completed in-class questionnaires that assessed smoking susceptibility and smoking initiation. Among the baseline sample of non-susceptible never-smokers, 45.2% of current e-cigarette users reported trying a cigarette after 2 years compared with 13.5% of non-current e-cigarette users. Among the baseline sample of susceptible never-smokers, 62.4% of current e-cigarette users reported trying a cigarette after 2 years compared with 36.1% of non-current e-cigarette users. Overall, current e-cigarette users were more likely to try a cigarette 2 years later. This association was stronger among the sample of non-susceptible never-smokers (AOR=5.28, 95% CI 2.81 to 9.94; pe-cigarette use may contribute to the development of a new population of cigarette smokers. They also support the notion that e-cigarettes are expanding the tobacco market by attracting low-risk youth who would otherwise be unlikely to initiate using cigarettes. Careful consideration will be needed in developing an appropriate regulatory framework that prevents e-cigarette use among youth. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless

  15. Generalized magnetic susceptibilities in metals: application of the analytic tetrahedron linear energy method to Sc

    International Nuclear Information System (INIS)

    Rath, J.; Freeman, A.J.

    1975-01-01

    A detailed study of the generalized susceptibility chi(vector q) of Sc metal determined from an accurate augmented-plane-wave method calculation of its energy-band structure is presented. The calculations were done by means of a computational scheme for chi(vector q) derived as an extension of the work of Jepsen and Andersen and Lehmann and Taut on the density-of-states problem. The procedure yields simple analytic expressions for the chi(vector q) integral inside a tetrahedral microzone of the Brillouin zone which depends only on the volume of the tetrahedron and the differences of the energies at its corners. Constant-matrix-element results have been obtained for Sc which show very good agreement with the results of Liu, Gupta, and Sinha (but with one less peak) and exhibit a first maximum in chi(vector q) at (0, 0, 0.31) 2π/c [vs (0, 0, 0.35) 2π/c obtained by Liu et al.] which relates very well to dilute rare-earth alloy magnetic ordering at vector q/sub m/ = (0, 0, 0.28) 2π/c and to the kink in the LA-phonon dispersion curve at (0, 0, 0.27) 2π/c. (U.S.)

  16. Nanosecond-resolved temperature measurements using magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Wenbiao; Zhang, Pu [School of Automation, Huazhong University of Science and Technology, Wuhan 430074 (China); Liu, Wenzhong, E-mail: lwz7410@hust.edu.cn [School of Automation, Huazhong University of Science and Technology, Wuhan 430074 (China); Key Laboratory of Image Processing and Intelligent Control, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2016-05-15

    Instantaneous and noninvasive temperature measurements are important when laser thermotherapy or welding is performed. A noninvasive nanosecond-resolved magnetic nanoparticle (MNP) temperature measurement system is described in which a transient change in temperature causes an instantaneous change in the magnetic susceptibilities of the MNPs. These transient changes in the magnetic susceptibilities are rapidly recorded using a wideband magnetic measurement system with an upper frequency limit of 0.5 GHz. The Langevin function (the thermodynamic model characterizing the MNP magnetization process) is used to obtain the temperature information. Experiments showed that the MNP DC magnetization temperature-measurement system can detect a 14.4 ns laser pulse at least. This method of measuring temperature is likely to be useful for acquiring the internal temperatures of materials irradiated with lasers, as well as in other areas of research.

  17. A new derivation of the plasma susceptibility tensor for a hot magnetized plasma without infinite sums of products of Bessel functions

    International Nuclear Information System (INIS)

    Qin Hong; Phillips, Cynthia K.; Davidson, Ronald C.

    2007-01-01

    The susceptibility tensor of a hot, magnetized plasma is conventionally expressed in terms of infinite sums of products of Bessel functions. For applications where the particle's gyroradius is larger than the wavelength, such as alpha particle dynamics interacting with lower-hybrid waves, and the focusing of charged particle beams using a solenoidal field, the infinite sums converge slowly. In this paper, a new derivation of the plasma susceptibility tensor is presented which exploits a symmetry in the particle's orbit to simplify the integration along the unperturbed trajectories. As a consequence, the infinite sums appearing in the conventional expression are replaced by definite double integrals over one gyroperiod, and the cyclotron resonances of all orders are captured by a single term. Furthermore, the double integrals can be carried out and expressed in terms of Bessel functions of complex order, in agreement with expressions deduced previously using the Newburger sum rule. From this new formulation, it is straightforward to derive the asymptotic form of the full hot plasma susceptibility tensor for a gyrotropic but otherwise arbitrary plasma distribution in the large gyroradius limit. These results are of more general importance in the numerical evaluation of the plasma susceptibility tensor. Instead of using the infinite sums occurring in the conventional expression, it is only necessary to evaluate the Bessel functions once according to the new expression, which has significant advantages, especially when the particle's gyroradius is large and the conventional infinite sums converge slowly. Depending on the size of the gyroradius, the computational saving enabled by this representation can be several orders-of-magnitude

  18. Magnetic study of the low temperature anomalies in the underdoped PrBCO compound

    Science.gov (United States)

    Lahoubi, Mahieddine

    2018-05-01

    The low temperature anomalous magnetic properties of a non-superconducting PrBCO6+x compound in an underdoped oxygen state of concentration (x = 0.44) are characterized by paraprocess magnetic susceptibility χH(T) measurements carried out as a function of temperature T under different values of a DC magnetic field H up to 110 kOe. The derivatives dχH(T)/dT curves reveal a significant reduction with increasing H in the Néel temperature TN = 9 K of the Pr antiferromagnetic (AFM) ordering for which the transition subsists at 100 kOe. The small anomaly at T2 = 6-7 K is confirmed at 20 kOe and the previous spin reorientation attributed to this transition temperature seems to be suppressed above 60 kOe. The well defined anomaly in the vicinity of the low-critical point Tcr = 4-5 K which occurs simultaneously, is still present when the strength of H is increased up to 100 kOe. Weak field induced phase transitions are observed between T2 and TN at a low transition-field (Ht<11 kOe) in the differential magnetic susceptibility dMT(H)/dH as a function of H deduced from the isothermal magnetizations MT(H) with H up to 21 kOe, whereas a weak ferromagnetic behavior of the Pr sublattice appears below Tcr. The magnetic field effects give rise to more evidence for the Pr-Cu(2) coupling with 'exchange-frustrated AFM' interactions and ascertain the main role of the Pr sublattice whereas the Cu(2) sublattice seems to be less efficient.

  19. Environmental studies in two communes of Santiago de Chile by the analysis of magnetic properties of particulate matter deposited on leaves of roadside trees

    Science.gov (United States)

    Muñoz, David; Aguilar, Bertha; Fuentealba, Raúl; Préndez, Margarita

    2017-03-01

    Emissions from motor vehicles are considered to be one of the main sources of airborne particulate matter in Santiago. International researchers have shown that particulate matter contains metal oxides and magnetic particles, both of which are emitted mainly from vehicles exhaust pipes. On the other hand, trees are effective in reducing such contamination, so that they act as passive collectors of particulate matter. This work presents the results obtained from the first magnetic study of the particulate matter collected in two areas of the city of Santiago de Chile. Magnetic susceptibility and Saturation Isothermic Remanent Magnetization (SIRM) were determined in leaves from abundant urban trees and from urban dust samples. Results indicate that most of the samples contain ferromagnetic minerals with magnetite (Fe3O4) as the main carrier. Values of magnetic susceptibility (SI ×10-6 m3/kg) in the range 0.04-0.24 for leaves and in the range 10-45 for urban dust were determinated. In one of the city areas studied, significant correlation between the particulate matter deposited on leaves of Platanus orientalis and measured traffic flows was obtained. In addition, it was possible to estimate that the species Platanus orientalis and Acer negundo have a better ability to capture particulate matter than the species Robinia pseudoacacia.

  20. Advantages of frequency-domain modeling in dynamic-susceptibility contrast magnetic resonance cerebral blood flow quantification.

    Science.gov (United States)

    Chen, Jean J; Smith, Michael R; Frayne, Richard

    2005-03-01

    In dynamic-susceptibility contrast magnetic resonance perfusion imaging, the cerebral blood flow (CBF) is estimated from the tissue residue function obtained through deconvolution of the contrast concentration functions. However, the reliability of CBF estimates obtained by deconvolution is sensitive to various distortions including high-frequency noise amplification. The frequency-domain Fourier transform-based and the time-domain singular-value decomposition-based (SVD) algorithms both have biases introduced into their CBF estimates when noise stability criteria are applied or when contrast recirculation is present. The recovery of the desired signal components from amid these distortions by modeling the residue function in the frequency domain is demonstrated. The basic advantages and applicability of the frequency-domain modeling concept are explored through a simple frequency-domain Lorentzian model (FDLM); with results compared to standard SVD-based approaches. The performance of the FDLM method is model dependent, well representing residue functions in the exponential family while less accurately representing other functions. (c) 2005 Wiley-Liss, Inc.

  1. Moessbauer and magnetic studies of parent material from argentine pampas soils

    International Nuclear Information System (INIS)

    Bidegain, J. C.; Bartel, A. A.; Sives, F. R.; Mercader, R. C.

    2007-01-01

    In order to establish a correlation between the different types of soils using hyperfine and magnetic parameters as climatic and environmental proxies, we have studied the differentiation of soil developed around 38.5 o south latitude, in the central Pampas of Argentina, by means of Moessbauer spectroscopy and environmental magnetism. The soils transect (climosequence) investigated stretches from the drier west (around 64 o W) to the more humid east (at around 59 o W) in the Buenos Aires Province, covering a distance of 600 km. The soils studied developed during recent Holocene geologic times in a landscape characterized by small relict plateaus, slopes and depressions, dunes and prairies. The parent material consists of eolian sandy silts overlying calcrete layers. The low mean annual precipitation in the western parts of the region gives rise to soils without B-horizons, which limits the agricultural use of land. The preliminary results show an increase of the paramagnetic Fe 3+ relative concentration from west to east in the soils investigated. Magnetite is probably mainly responsible for the observed enhancement in the susceptibility values. The magnetic response of the parent material is similar to that of the loess part of the previously investigated loess-paleosol sequences of the Argentine loess plateau.

  2. SCC susceptibility of cold-worked stainless steel with minor element additions

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, Junichi, E-mail: nakano.junnichi@jaea.go.jp [Japan Atomic Energy Agency, Shirakatashirane 2-4, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 (Japan); Nemoto, Yoshiyuki, E-mail: yoshiyuki.nemoto@oecd.org [OECD Nuclear Energy Agency, Le Seine St-Germain, 12, boulevard des Iles, F-92130 Issy-les-Moulineaux (France); Tsukada, Takashi, E-mail: tsukada.takashi@jaea.go.jp [Japan Atomic Energy Agency, Shirakatashirane 2-4, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 (Japan); Uchimoto, Tetsuya, E-mail: uchimoto@ifs.tohoku.ac.jp [Tohoku University, Aoba-ku, Sendai-shi, Miyagi-ken 980-8577 (Japan)

    2011-10-01

    To examine the effects of minor elements on stress corrosion cracking (SCC) susceptibility of low carbon stainless steels with a work hardened layer, a high purity type 304 stainless steel was fabricated and minor elements, Si, S, P, C or Ti, were added. A work hardened layer was introduced by shaving on the surface of stainless steels. The specimens were exposed to a boiling 42% MgCl{sub 2} solution for 20 h and the number and the length of initiated cracks were examined. SCC susceptibility of the specimen with P was the highest and that of the specimen with C was the lowest in all specimens. By magnetic force microscope examination, a magnetic phase expected to be a martensitic phase was detected near the surface. Since corrosion resistance of martensite is lower than that of austenite, the minor elements additions would affect SCC susceptibility through the amount of the transformed martensite.

  3. Magnetic properties of alluvial soils polluted with heavy metals

    Science.gov (United States)

    Dlouha, S.; Petrovsky, E.; Boruvka, L.; Kapicka, A.; Grison, H.

    2012-04-01

    Magnetic properties of soils, reflecting mineralogy, concentration and grain-size distribution of Fe-oxides, proved to be useful tool in assessing the soil properties in terms of various environmental conditions. Measurement of soil magnetic properties presents a convenient method to investigate the natural environmental changes in soils as well as the anthropogenic pollution of soils with several risk elements. The effect of fluvial pollution with Cd, Cu, Pb and Zn on magnetic soil properties was studied on highly contaminated alluvial soils from the mining/smelting district (Příbram; CZ) using a combination of magnetic and geochemical methods. The basic soil characteristics, the content of heavy metals, oxalate, and dithionite extractable iron were determined in selected soil samples. Soil profiles were sampled using HUMAX soil corer and the magnetic susceptibility was measured in situ, further detailed magnetic analyses of selected distinct layers were carried out. Two types of variations of magnetic properties in soil profiles were observed corresponding to indentified soil types (Fluvisols, and Gleyic Fluvisols). Significantly higher values of topsoil magnetic susceptibility compared to underlying soil are accompanied with high concentration of heavy metals. Sequential extraction analysis proved the binding of Pb, Zn and Cd in Fe and Mn oxides. Concentration and size-dependent parameters (anhysteretic and isothermal magnetization) were measured on bulk samples in terms of assessing the origin of magnetic components. The results enabled to distinguish clearly topsoil layers enhanced with heavy metals from subsoil samples. The dominance of particles with pseudo-single domain behavior in topsoil and paramagnetic/antiferromagnetic contribution in subsoil were observed. These measurements were verified with room temperature hysteresis measurement carried out on bulk samples and magnetic extracts. Thermomagnetic analysis of magnetic susceptibility measured on

  4. Magnetic signature of industrial pollution of stream sediments and correlation with heavy metals: case study from South France

    Czech Academy of Sciences Publication Activity Database

    Desenfant, F.; Petrovský, Eduard; Rochette, P.

    2004-01-01

    Roč. 152, 1/4 (2004), s. 297-312 ISSN 0049-6979 R&D Projects: GA AV ČR KSK3012103 Institutional research plan: CEZ:AV0Z3012916 Keywords : Arc river * heavy metals * magnetic susceptibility Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 1.058, year: 2004

  5. Thermally-activated vortex dynamics in bismuth calcium strontium copper oxide (Bi2CaSr2Cu2O8+δ) studied by complex susceptibility measurements

    NARCIS (Netherlands)

    Emmen, J.H.P.M.; Brabers, V.A.M.; Jonge, de W.J.M.

    1991-01-01

    Complex AC magnetic susceptibility has been measured on Bi2CaSr2Cu2O8+d single crystals with hnc, Hdc|c-axis. It will be shown that field, frequency and temperature dependence of both ¿' and ¿¿ in a constant but sufficiently large DC magnetic field can quantitatively be described by

  6. Orbital magnetism in ensembles of ballistic billiards

    International Nuclear Information System (INIS)

    Ullmo, D.; Richter, K.; Jalabert, R.A.

    1993-01-01

    The magnetic response of ensembles of small two-dimensional structures at finite temperatures is calculated. Using semiclassical methods and numerical calculation it is demonstrated that only short classical trajectories are relevant. The magnetic susceptibility is enhanced in regular systems, where these trajectories appear in families. For ensembles of squares large paramagnetic susceptibility is obtained, in good agreement with recent measurements in the ballistic regime. (authors). 20 refs., 2 figs

  7. Environmental magnetism and magnetic mapping of urban metallic pollution (Paris, France)

    Science.gov (United States)

    Isambert, Aude; Franke, Christine; Macouin, Mélina; Rousse, Sonia; Philip, Aurélio; de Villeneuve, Sybille Henry

    2017-04-01

    Airborne pollution in dense urban areas is nowadays a subject of major concern. Fine particulate pollution events are ever more frequent and represent not only an environmental and health but also a real economic issue. In urban atmosphere, the so-called PM2.5 (particulate matter pollution and determine their sources (Sagnotti et al., 2012). In this study, we report on magnetic measurements of traffic-related airborne PM in the city of Paris, France. Two distinct environments were sampled and analyzed along the Seine River: the aquatic environment in studying fluvial bank and river bed sediments and the atmospheric environment by regarding magnetic particles trapped in adjacent tree barks (Platanus hispanica). About 50 sediment samples and 350 bark samples have been collected and analysed to determine their magnetic properties (susceptibility, hysteresis parameters, IRM, frequency-dependent susceptibility) and to estimate the presence and spatial concentration of superparamagnetic or multi-domain particles for each sample type. The bark results allow proposing a high spatial resolution mapping (pollution. In addition to that, the sampling of banks and riverbed sediments of the Seine allow a global estimation on the anthropogenic versus detrital and biologic input in the city of Paris. The first results presented here show a general increase of the concentration in magnetic particles from upstream to downstream Paris probably linked to urban pollutions as previously observed for suspended particulate matter (Franke et al. 2009; Kayvantash, 2016). Sagnotti, L., & Winkler, A. (2012). On the magnetic characterization and quantification of the superparamagnetic fraction of traffic-related urban airborne PM in Rome, Italy. Atmospheric environment, 59, 131-140. Franke, C., Kissel, C., Robin, E., Bonté, P., & Lagroix, F. (2009). Magnetic particle characterization in the Seine river system: Implications for the determination of natural versus anthropogenic input

  8. Fundamental studies of superconductors using scanning magnetic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kirtley, J R [Center for Probing the Nanoscale, Stanford University, Stanford, CA (United States)

    2010-12-01

    in rings of highly underdoped cuprates places limits on spin-charge separation in these materials. Studies of spontaneous generation of fluxoids upon cooling rings through the superconducting transition provide clues to dynamical processes relevant to the early development of the universe, while studies of vortex motion in cuprate grain boundaries allow the measurement of current-voltage characteristics at the femtovolt scale for these technologically important defects. Scanning SQUID susceptometry allows the measurement of superconducting fluctuations on samples comparable in size to the coherence length, revealing stripes in susceptibility believed to be associated with enhanced superfluid density on the twin boundaries in the pnictide superconductor Co doped Ba-122, and indicating the presence of spin-like excitations, which may be a source of noise in superconducting devices, in a wide variety of materials. Scanning magnetic microscopies allow the absolute value of penetration depths to be measured locally over a wide temperature range, providing clues to the symmetry of the order parameter in unconventional superconductors. Finally, MFM tips can be used to manipulate vortices, providing information on flux trapping in superconductors.

  9. Fundamental studies of superconductors using scanning magnetic imaging

    Science.gov (United States)

    Kirtley, J. R.

    2010-12-01

    cuprates places limits on spin-charge separation in these materials. Studies of spontaneous generation of fluxoids upon cooling rings through the superconducting transition provide clues to dynamical processes relevant to the early development of the universe, while studies of vortex motion in cuprate grain boundaries allow the measurement of current-voltage characteristics at the femtovolt scale for these technologically important defects. Scanning SQUID susceptometry allows the measurement of superconducting fluctuations on samples comparable in size to the coherence length, revealing stripes in susceptibility believed to be associated with enhanced superfluid density on the twin boundaries in the pnictide superconductor Co doped Ba-122, and indicating the presence of spin-like excitations, which may be a source of noise in superconducting devices, in a wide variety of materials. Scanning magnetic microscopies allow the absolute value of penetration depths to be measured locally over a wide temperature range, providing clues to the symmetry of the order parameter in unconventional superconductors. Finally, MFM tips can be used to manipulate vortices, providing information on flux trapping in superconductors.

  10. Microfacies description linked to the magnetic and non-magnetic proxy as a promising environmental tool: Case study from alluvial deposits of the Nile river

    Czech Academy of Sciences Publication Activity Database

    Lisá, Lenka; Lisý, Pavel; Chadima, Martin; Čejchan, Petr; Bajer, A.; Cílek, Václav; Suková, L.; Schnabl, Petr

    2012-01-01

    Roč. 266, July (2012), s. 25-33 ISSN 1040-6182 Institutional research plan: CEZ:AV0Z30130516 Keywords : Frequency dependent magnetic susceptibility * alluvium * Nile * grain size * TOC * human impact Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.962, year: 2012

  11. Assessing MRI susceptibility artefact through an indicator of image distortion

    Directory of Open Access Journals (Sweden)

    Illanes Alfredo

    2016-09-01

    Full Text Available Susceptibility artefacts in magnetic resonance imaging (MRI caused by medical devices can result in a severe degradation of the MR image quality. The quantification of susceptibility artefacts is regulated by the ASTM standard which defines a manual method to assess the size of an artefact. This means that the estimated artefact size can be user dependent. To cope with this problem, we propose an algorithm to automatically quantify the size of such susceptibility artefacts. The algorithm is based on the analysis of a 3D surface generated from the 2D MR images. The results obtained by the automatic algorithm were compared to the manual measurements performed by study participants. The results show that the automatic and manual measurements follow the same trend. The clear advantage of the automated algorithm is the absence of the inter- and intra-observer variability. In addition, the algorithm also detects the slice containing the largest artefact which was not the case for the manual measurements.

  12. Quantitative and qualitative assessment of structural magnetic resonance imaging data in a two-center study

    OpenAIRE

    Chalavi Sima; Simmons Andrew; Dijkstra Hildebrand; Barker Gareth J; Reinders AAT Simone

    2012-01-01

    Abstract Background Multi-center magnetic resonance imaging (MRI) studies present an opportunity to advance research by pooling data. However, brain measurements derived from MR-images are susceptible to differences in MR-sequence parameters. It is therefore necessary to determine whether there is an interaction between the sequence parameters and the effect of interest, and to minimise any such interaction by careful choice of acquisition parameters. As an exemplar of the issues involved in ...

  13. Local order and magnetism of amorphous and disordered solids

    International Nuclear Information System (INIS)

    Friedt, J.M.

    1985-01-01

    Some topics related with the magnetic properties and local order in amorphous and disordered solids studied by Moessbauer spectroscopy, EXAFS, static and dynamical susceptibilities are presented. (L.C.) [pt

  14. Hydrothermally-induced changes in mineralogy and magnetic properties of oxidized A-type granites

    Science.gov (United States)

    Nédélec, Anne; Trindade, Ricardo; Peschler, Anne; Archanjo, Carlos; Macouin, Mélina; Poitrasson, Franck; Bouchez, Jean-Luc

    2015-01-01

    The changes in magnetic mineralogy due to the hydrothermal alteration of A-type granitic rocks have been thoroughly investigated in samples from the granite of Tana (Corsica, France), and compared with other A-type granites: Meruoca (NE Brazil), Bushveld (South Africa), Mount Scott (Wichita Mountains, Oklahoma, USA) and the stratoid hypersolvus granites of Madagascar. The altered red-colored samples and their non-altered equivalents were magnetically characterized by means of magnetic susceptibility measurements, hysteresis loops, remanent coercivity spectra, and Lowrie test. It is shown that hydrothermalization in magnetite-bearing granites is related to the formation of fine-grained magnetite and hematite, and to coeval depletion in the content of primary low-coercive coarse-grained magnetite. These mineralogical changes give typical rock magnetic signatures, namely lower susceptibility magnitudes and anisotropy degrees, prolate AMS (anisotropy of magnetic susceptibility) fabrics and increased coercivities. Optical microscopy and SEM (scanning electronic microscopy) images suggest that the orientation of the secondary magnetic minerals is related to fluid-pathways and micro-fractures formed during the hydrothermal event and therefore may be unrelated to magma emplacement and crystallization fabrics. Changes in magnetic mineralogy and grain-size distribution have also to be considered for any paleomagnetic and iron isotope studies in granites.

  15. Magnetic particles as tracers of industrial pollution

    Czech Academy of Sciences Publication Activity Database

    Petrovský, Eduard; Kapička, Aleš; Jordanova, Neli; Fialová, Hana

    č. 26 (2002), s. 131-132 ISSN 1590-2595. [Fundamental rock magnetism and environmental applications. Erice, 26.06.2002-01.07.2002] Institutional research plan: CEZ:AV0Z3012916 Keywords : magnetic particles * industrial pollution * fly ashes * magnetic susceptibility Subject RIV: DE - Earth Magnetism, Geodesy, Geography

  16. Development of a magnetic nanoparticle susceptibility magnitude imaging array

    International Nuclear Information System (INIS)

    Ficko, Bradley W; Nadar, Priyanka M; Hoopes, P Jack; Diamond, Solomon G

    2014-01-01

    There are several emerging diagnostic and therapeutic applications of magnetic nanoparticles (mNPs) in medicine. This study examines the potential for developing an mNP imager that meets these emerging clinical needs with a low cost imaging solution that uses arrays of digitally controlled drive coils in a multiple-frequency, continuous-wave operating mode and compensated fluxgate magnetometers. The design approach is described and a mathematical model is developed to support measurement and imaging. A prototype is used to demonstrate active compensation of up to 185 times the primary applied magnetic field, depth sensitivity up to 2.5 cm (p < 0.01), and linearity over five dilutions (R 2  > 0.98, p < 0.001). System frequency responses show distinguishable readouts for iron oxide mNPs with single magnetic domain core diameters of 10 and 40 nm, and multi-domain mNPs with a hydrodynamic diameter of 100 nm. Tomographic images show a contrast-to-noise ratio of 23 for 0.5 ml of 12.5 mg Fe ml −1  mNPs at 1 cm depth. A demonstration involving the injection of mNPs into pork sausage shows the potential for use in biological systems. These results indicate that the proposed mNP imaging approach can potentially be extended to a larger array system with higher-resolution. (paper)

  17. Genome-wide association study identifies novel breast cancer susceptibility loci

    Science.gov (United States)

    Easton, Douglas F.; Pooley, Karen A.; Dunning, Alison M.; Pharoah, Paul D. P.; Thompson, Deborah; Ballinger, Dennis G.; Struewing, Jeffery P.; Morrison, Jonathan; Field, Helen; Luben, Robert; Wareham, Nicholas; Ahmed, Shahana; Healey, Catherine S.; Bowman, Richard; Meyer, Kerstin B.; Haiman, Christopher A.; Kolonel, Laurence K.; Henderson, Brian E.; Marchand, Loic Le; Brennan, Paul; Sangrajrang, Suleeporn; Gaborieau, Valerie; Odefrey, Fabrice; Shen, Chen-Yang; Wu, Pei-Ei; Wang, Hui-Chun; Eccles, Diana; Evans, D. Gareth; Peto, Julian; Fletcher, Olivia; Johnson, Nichola; Seal, Sheila; Stratton, Michael R.; Rahman, Nazneen; Chenevix-Trench, Georgia; Bojesen, Stig E.; Nordestgaard, Børge G.; Axelsson, Christen K.; Garcia-Closas, Montserrat; Brinton, Louise; Chanock, Stephen; Lissowska, Jolanta; Peplonska, Beata; Nevanlinna, Heli; Fagerholm, Rainer; Eerola, Hannaleena; Kang, Daehee; Yoo, Keun-Young; Noh, Dong-Young; Ahn, Sei-Hyun; Hunter, David J.; Hankinson, Susan E.; Cox, David G.; Hall, Per; Wedren, Sara; Liu, Jianjun; Low, Yen-Ling; Bogdanova, Natalia; Schürmann, Peter; Dörk, Thilo; Tollenaar, Rob A. E. M.; Jacobi, Catharina E.; Devilee, Peter; Klijn, Jan G. M.; Sigurdson, Alice J.; Doody, Michele M.; Alexander, Bruce H.; Zhang, Jinghui; Cox, Angela; Brock, Ian W.; MacPherson, Gordon; Reed, Malcolm W. R.; Couch, Fergus J.; Goode, Ellen L.; Olson, Janet E.; Meijers-Heijboer, Hanne; van den Ouweland, Ans; Uitterlinden, André; Rivadeneira, Fernando; Milne, Roger L.; Ribas, Gloria; Gonzalez-Neira, Anna; Benitez, Javier; Hopper, John L.; McCredie, Margaret; Southey, Melissa; Giles, Graham G.; Schroen, Chris; Justenhoven, Christina; Brauch, Hiltrud; Hamann, Ute; Ko, Yon-Dschun; Spurdle, Amanda B.; Beesley, Jonathan; Chen, Xiaoqing; Mannermaa, Arto; Kosma, Veli-Matti; Kataja, Vesa; Hartikainen, Jaana; Day, Nicholas E.; Cox, David R.; Ponder, Bruce A. J.; Luccarini, Craig; Conroy, Don; Shah, Mitul; Munday, Hannah; Jordan, Clare; Perkins, Barbara; West, Judy; Redman, Karen; Driver, Kristy; Aghmesheh, Morteza; Amor, David; Andrews, Lesley; Antill, Yoland; Armes, Jane; Armitage, Shane; Arnold, Leanne; Balleine, Rosemary; Begley, Glenn; Beilby, John; Bennett, Ian; Bennett, Barbara; Berry, Geoffrey; Blackburn, Anneke; Brennan, Meagan; Brown, Melissa; Buckley, Michael; Burke, Jo; Butow, Phyllis; Byron, Keith; Callen, David; Campbell, Ian; Chenevix-Trench, Georgia; Clarke, Christine; Colley, Alison; Cotton, Dick; Cui, Jisheng; Culling, Bronwyn; Cummings, Margaret; Dawson, Sarah-Jane; Dixon, Joanne; Dobrovic, Alexander; Dudding, Tracy; Edkins, Ted; Eisenbruch, Maurice; Farshid, Gelareh; Fawcett, Susan; Field, Michael; Firgaira, Frank; Fleming, Jean; Forbes, John; Friedlander, Michael; Gaff, Clara; Gardner, Mac; Gattas, Mike; George, Peter; Giles, Graham; Gill, Grantley; Goldblatt, Jack; Greening, Sian; Grist, Scott; Haan, Eric; Harris, Marion; Hart, Stewart; Hayward, Nick; Hopper, John; Humphrey, Evelyn; Jenkins, Mark; Jones, Alison; Kefford, Rick; Kirk, Judy; Kollias, James; Kovalenko, Sergey; Lakhani, Sunil; Leary, Jennifer; Lim, Jacqueline; Lindeman, Geoff; Lipton, Lara; Lobb, Liz; Maclurcan, Mariette; Mann, Graham; Marsh, Deborah; McCredie, Margaret; McKay, Michael; McLachlan, Sue Anne; Meiser, Bettina; Milne, Roger; Mitchell, Gillian; Newman, Beth; O'Loughlin, Imelda; Osborne, Richard; Peters, Lester; Phillips, Kelly; Price, Melanie; Reeve, Jeanne; Reeve, Tony; Richards, Robert; Rinehart, Gina; Robinson, Bridget; Rudzki, Barney; Salisbury, Elizabeth; Sambrook, Joe; Saunders, Christobel; Scott, Clare; Scott, Elizabeth; Scott, Rodney; Seshadri, Ram; Shelling, Andrew; Southey, Melissa; Spurdle, Amanda; Suthers, Graeme; Taylor, Donna; Tennant, Christopher; Thorne, Heather; Townshend, Sharron; Tucker, Kathy; Tyler, Janet; Venter, Deon; Visvader, Jane; Walpole, Ian; Ward, Robin; Waring, Paul; Warner, Bev; Warren, Graham; Watson, Elizabeth; Williams, Rachael; Wilson, Judy; Winship, Ingrid; Young, Mary Ann; Bowtell, David; Green, Adele; deFazio, Anna; Chenevix-Trench, Georgia; Gertig, Dorota; Webb, Penny

    2009-01-01

    Breast cancer exhibits familial aggregation, consistent with variation in genetic susceptibility to the disease. Known susceptibility genes account for less than 25% of the familial risk of breast cancer, and the residual genetic variance is likely to be due to variants conferring more moderate risks. To identify further susceptibility alleles, we conducted a two-stage genome-wide association study in 4,398 breast cancer cases and 4,316 controls, followed by a third stage in which 30 single nucleotide polymorphisms (SNPs) were tested for confirmation in 21,860 cases and 22,578 controls from 22 studies. We used 227,876 SNPs that were estimated to correlate with 77% of known common SNPs in Europeans at r2>0.5. SNPs in five novel independent loci exhibited strong and consistent evidence of association with breast cancer (P<10−7). Four of these contain plausible causative genes (FGFR2, TNRC9, MAP3K1 and LSP1). At the second stage, 1,792 SNPs were significant at the P<0.05 level compared with an estimated 1,343 that would be expected by chance, indicating that many additional common susceptibility alleles may be identifiable by this approach. PMID:17529967

  18. Monte Carlo method for magnetic impurities in metals

    Science.gov (United States)

    Hirsch, J. E.; Fye, R. M.

    1986-01-01

    The paper discusses a Monte Carlo algorithm to study properties of dilute magnetic alloys; the method can treat a small number of magnetic impurities interacting wiith the conduction electrons in a metal. Results for the susceptibility of a single Anderson impurity in the symmetric case show the expected universal behavior at low temperatures. Some results for two Anderson impurities are also discussed.

  19. Magnetic properties of sheet silicates

    International Nuclear Information System (INIS)

    Ballet, O.; Coey, J.M.D.

    1982-01-01

    Susceptibility, magnetisation and Moessbauer measurements are reported for a representative selection of 2:1 layer phyllosilicates. Eight samples from the mica, vermiculite and smectite groups include examples diluted in iron which are paramagnetic at all temperatures, as well as iron-rich silicates which order magnetically below 10 K. Anisotropic susceptibility of crystals of muscovite, biotite and vermiculite is quantitatively explained with a model where the Fe 2+ ions lie in sites of effective trigonal symmetry, the trigonal axis lying normal to the sheets. The ferrous ground state is an orbital singlet. Ferric iron gives an isotropic contribution to the susceptibility. Fe 2+ -Fe 2+ exchange interactions are ferromagnetic with Gapprox. equal to2 K, whereas Fe 3+ -Fe 3+ coupling is antiferromagnetic in the purely ferric minerals. A positive paramagnetic Curie temperature for glauconite may be attributable to Fe 2+ → Fe 3+ charge transfer. Magnetic order was found to set in inhomogeneously for glauconite at 1-7 K. One biotite sample showed an antiferromagnetic transition at Tsub(N) = 7 K marked by a well-defined susceptibility maximum. Its magnetic structure, consisting of ferromagnetic sheets with moments in their planes coupled antiferromagnetically by other, weak interactions, resembles that found earlier for the 1:1 mineral greenalite. (orig.)

  20. A wheel-shaped single-molecule magnet of [MnII 3MnIII 4]: quantum tunneling of magnetization under static and pulse magnetic fields.

    Science.gov (United States)

    Koizumi, Satoshi; Nihei, Masayuki; Shiga, Takuya; Nakano, Motohiro; Nojiri, Hiroyuki; Bircher, Roland; Waldmann, Oliver; Ochsenbein, Stefan T; Güdel, Hans U; Fernandez-Alonso, Felix; Oshio, Hiroki

    2007-01-01

    The reaction of N-(2-hydroxy-5-nitrobenzyl)iminodiethanol (=H3(5-NO2-hbide)) with Mn(OAc)2* 4 H2O in methanol, followed by recrystallization from 1,2-dichloroethane, yielded a wheel-shaped single-molecule magnet (SMM) of [MnII 3MnIII 4(5-NO2-hbide)6].5 C2H4Cl2 (1). In 1, seven manganese ions are linked by six tri-anionic ligands and form the wheel in which the two manganese ions on the rim and the one in the center are MnII and the other four manganese ions are MnIII ions. Powder magnetic susceptibility measurements showed a gradual increase with chimT values as the temperature was lowered, reaching a maximum value of 53.9 emu mol(-1) K. Analyses of magnetic susceptibility data suggested a spin ground state of S=19/2. The zero-field splitting parameters of D and B 0 4 were estimated to be -0.283(1) K and -1.64(1)x10(-5) K, respectively, by high-field EPR measurements (HF-EPR). The anisotropic parameters agreed with those estimated from magnetization and inelastic neutron scattering experiments. AC magnetic susceptibility measurements showed frequency-dependent in- and out-of-phase signals, characteristic data for an SMM, and an Arrhenius plot of the relaxation time gave a re-orientation energy barrier (DeltaE) of 18.1 K and a pre-exponential factor of 1.63x10(-7) s. Magnetization experiments on aligned single crystals below 0.7 K showed a stepped hysteresis loop, confirming the occurrence of quantum tunneling of the on magnetization (QTM). QTM was, on the other hand, suppressed by rapid sweeps of the magnetic field even at 0.5 K. The sweep-rate dependence of the spin flips can be understood by considering the Landau-Zener-Stückelberg (LZS) model.

  1. Magnetic properties of cores from the Wenchuan Earthquake Fault Scientific Drilling Hole-2 (WFSD-2), China

    Science.gov (United States)

    Zhang, L., Jr.; Sun, Z.; Li, H.; Cao, Y.; Ye, X.; Wang, L.; Zhao, Y.; Han, S.

    2015-12-01

    During an earthquake, seismic slip and frictional heating may cause the physical and chemical alterations of magnetic minerals within the fault zone. Rock magnetism provides a method for understanding earthquake dynamics. The Wenchuan earthquake Fault Scientific Drilling Project (WFSD) started right after 2008 Mw7.9 Wenchuan earthquake, to investigate the earthquake faulting mechanism. Hole 2 (WFSD-2) is located in the Pengguan Complex in the Bajiaomiao village (Dujiangyan, Sichuan), and reached the Yingxiu-Beichuan fault (YBF). We measured the surface magnetic susceptibility of the cores in WFSD-2 from 500 m to 1530 m with an interval of 1 cm. Rocks at 500-599.31 m-depth and 1211.49-1530 m-depth are from the Neoproterozoic Pengguang Complex while the section from 599.31 m to 1211.49 m is composed of Late Triassic sediments. The magnetic susceptibility values of the first part of the Pengguan Complex range from 1 to 25 × 10-6 SI, while the second part ranges from 10 to 200 × 10-6 SI, which indicate that the two parts are not from the same rock units. The Late Triassic sedimentary rocks have a low magnetic susceptibility values, ranging from -5 to 20 × 10-6 SI. Most fault zones coincide with the high value of magnetic susceptibility in the WFSD-2 cores. Fault rocks, mainly fault breccia, cataclasite, gouge and pseudotachylite within the WFSD-2 cores, and mostly display a significantly higher magnetic susceptibility than host rocks (5:1 to 20:1). In particular, in the YBF zone of the WFSD-2 cores (from 600 to 960 m), dozens of stages with high values of magnetic susceptibility have been observed. The multi-layered fault rocks with high magnetic susceptibility values might indicate that the YBF is a long-term active fault. The magnetic susceptibility values change with different types of fault rocks. The gouge and pseudotachylite have higher values of magnetic susceptibility than other fault rocks. Other primary rock magnetism analyses were then performed to

  2. Effect of gamma radiation on the magnetic properties of a carbon-fiber-reinforced plastic with a polysulfone matrix

    International Nuclear Information System (INIS)

    Rodin, Yu.P.; Arkhipov, A.A.; Korkhov, V.P.; Pudnik, V.V.

    1994-01-01

    In the present article, the authors report results of a study of the change in the magnetic susceptibility of a carbon-fiber-reinforced plastic based on a thermoplastic matrix -- aromatic polysulfone -- in relation to the absorbed dose of γ-radiation. The study results show that the change in the magnetic susceptibility of specimens which have absorbed different doses of gamma radiation correlates with the change in their mechanical properties, thermal behavior, and structural changes. A method is described for measuring susceptibility which can be used successfully to study the structure and properties of polymer materials and composites based on them. 3 refs., 3 figs

  3. Measurement of weak electric currents in copper wire phantoms using MRI: influence of susceptibility enhancement.

    Science.gov (United States)

    Huang, Ruiwang; Posnansky, Oleg; Celik, Abdullah; Oros-Peusquens, Ana-Maria; Ermer, Veronika; Irkens, Marco; Wegener, H-Peter; Shah, N Jon

    2006-08-01

    The use of magnetic resonance imaging (MRI)-based methods for the direct detection of neuronal currents is a topic of intense investigation. Much experimental work has been carried out with the express aim of establishing detection thresholds and sensitivity to flowing currents. However, in most of these experiments, magnetic susceptibility enhancement was ignored. In this work, we present results that show the influence of a susceptibility artefact on the detection threshold and sensitivity. For this purpose, a novel phantom, consisting of a water-filled cylinder with two wires of different materials connected in series, was constructed. Magnitude MR images were acquired from a single slice using a gradient-echo echo planar imaging (EPI) sequence. The data show that the time course of the detected MR signal magnitude correlates very well with the waveform of the input current. The effect of the susceptibility artefacts arising from the two different wires was examined by comparing the magnitudes of the MR signals at different voxel locations. Our results indicate the following: (1) MR signal enhancement arising from the magnetic susceptibility effect influences the detection sensitivity of weak current; (2) the detection threshold and sensitivity are phantom-wire dependent; (3) sub-mu A electric current detection in a phantom is possible on a 1.5-T MR scanner in the presence of susceptibility enhancement.

  4. Magnetic properties of singlet ground state systems

    International Nuclear Information System (INIS)

    Diederix, K.M.

    1979-01-01

    Experiments are described determining the properties of a magnetic system consisting of a singlet ground state. Cu(NO 3 ) 2 .2 1/2H 2 O has been studied which is a system of S = 1/2 alternating antiferromagnetic Heisenberg chains. The static properties, spin lattice relaxation time and field-induced antiferromagnetically ordered state measurements are presented. Susceptibility and magnetic cooling measurements of other compounds are summarised. (Auth.)

  5. c-axis ac susceptibility in high-Tc superconductors

    International Nuclear Information System (INIS)

    Waldmann, O.; Lichtschlag, G.; Talalaevskii, A.; Kleiner, R.; Mueller, P.; Steinmeyer, F.; Gerhaeuser, W.

    1996-01-01

    We have investigated the angle and magnetic field dependence of the ac susceptibility in Bi 2 Sr 2 CaCu 2 O 8 and YBa 2 Cu 3 O 7 single crystals at low external fields. The ac field was applied perpendicular to the CuO 2 planes. The first and third harmonics of the ac susceptibility exhibit remarkably sharp features when the dc field component perpendicular to the CuO 2 planes passes a threshold field H th . H th is strongly temperature dependent, but is independent of the parallel field component. We propose a simple model which excellently explains the data. Within this model the peak structures are related to the irreversibility line. We discuss the implications of the model for the interpretation of the ac susceptibility. copyright 1996 The American Physical Society

  6. Theoretical investigation of electronic and magnetic properties of MnAu layers

    Energy Technology Data Exchange (ETDEWEB)

    Masrour, R., E-mail: rachidmasrour@hotmail.com [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, BP 63, 46000, Sidi Bouzid, Safi (Morocco); LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Hlil, E.K. [Institut Neel, CNRS et Universite Joseph Fourier, BP 166, F-38042 Grenoble cedex 9 (France); Hamedoun, M. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Benyoussef, A. [LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco); Mounkachi, O. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Bahmad, L. [LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco)

    2013-01-15

    Self-consistent ab initio calculations, based on the density functional theory (DFT) approach and using the full potential linear augmented plane wave (FLAPW) method, are performed to investigate both electronic and magnetic properties of the MnAu layers. Polarized spin and spin-orbit coupling are included in calculations within the framework of the antiferromagnetic state between two adjacent Mn layers. Magnetic moment considered to lie along a axes are computed. The data obtained from the ab initio calculations are then used as input for the high temperature series expansions (HTSEs) calculation to compute other magnetic parameters. The exchange integrals between the magnetic atoms in the same layer and between the magnetic atoms in the bilayers adjacent are given by using mean field theory. The HTSEs of the magnetic susceptibility of MnAu antiferromagnetic spin-S through two model: Ising and XY layers consisting of l=2, 3, 4, 5, 6 and bulk ({infinity}) interacting layers, are studied to sixth order series in {beta}=1/k{sub B}T obtained for free-surface boundary conditions. The effects of finite size on critical-point behavior are studied by extrapolation of the high-temperature series. The Neel temperature T{sub N}(l) as a function of the number of l spin layers is obtained by HTSEs of the magnetic susceptibility series by using the Pade approximant method and by MFT theory. The critical exponent {gamma} associated with the magnetic susceptibility is deduced. T{sub N}(l) for the l-layers are estimated from the divergence of the staggered susceptibility with an exponent for Ising model of {gamma}(1)=2.96, and for XY model of {gamma}(2)=2.82, which is consistent with the basic assumptions of scaling laws. Our estimates for the shift exponent of the Neel temperature for the two models are obtained. - Highlights: Black-Right-Pointing-Pointer ab initio calculations is using to investigate both electronic and magnetic properties of the MnAu layers. Black

  7. Theoretical investigation of electronic and magnetic properties of MnAu layers

    International Nuclear Information System (INIS)

    Masrour, R.; Hlil, E.K.; Hamedoun, M.; Benyoussef, A.; Mounkachi, O.; Bahmad, L.

    2013-01-01

    Self-consistent ab initio calculations, based on the density functional theory (DFT) approach and using the full potential linear augmented plane wave (FLAPW) method, are performed to investigate both electronic and magnetic properties of the MnAu layers. Polarized spin and spin–orbit coupling are included in calculations within the framework of the antiferromagnetic state between two adjacent Mn layers. Magnetic moment considered to lie along a axes are computed. The data obtained from the ab initio calculations are then used as input for the high temperature series expansions (HTSEs) calculation to compute other magnetic parameters. The exchange integrals between the magnetic atoms in the same layer and between the magnetic atoms in the bilayers adjacent are given by using mean field theory. The HTSEs of the magnetic susceptibility of MnAu antiferromagnetic spin-S through two model: Ising and XY layers consisting of l=2, 3, 4, 5, 6 and bulk (∞) interacting layers, are studied to sixth order series in β=1/k B T obtained for free-surface boundary conditions. The effects of finite size on critical-point behavior are studied by extrapolation of the high-temperature series. The Néel temperature T N (l) as a function of the number of l spin layers is obtained by HTSEs of the magnetic susceptibility series by using the Padé approximant method and by MFT theory. The critical exponent γ associated with the magnetic susceptibility is deduced. T N (l) for the l-layers are estimated from the divergence of the staggered susceptibility with an exponent for Ising model of γ(1)=2.96, and for XY model of γ(2)=2.82, which is consistent with the basic assumptions of scaling laws. Our estimates for the shift exponent of the Néel temperature for the two models are obtained. - Highlights: ► ab initio calculations is using to investigate both electronic and magnetic properties of the MnAu layers. ► Obtained data from ab initio calculations are used as input for the HTSEs

  8. Investigating hyperoxic effects in the rat brain using quantitative susceptibility mapping based on MRI phase.

    Science.gov (United States)

    Hsieh, Meng-Chi; Kuo, Li-Wei; Huang, Yun-An; Chen, Jyh-Horng

    2017-02-01

    To test whether susceptibility imaging can detect microvenous oxygen saturation changes, induced by hyperoxia, in the rat brain. A three-dimensional gradient-echo with a flow compensation sequence was used to acquire T2*-weighted images of rat brains during hyperoxia and normoxia. Quantitative susceptibility mapping (QSM) and QSM-based microvenous oxygenation venography were computed from gradient-echo (GRE) phase images and compared between the two conditions. Pulse oxygen saturation (SpO 2 ) in the cortex was examined and compared with venous oxygen saturation (SvO 2 ) estimated by QSM. Oxygen saturation change calculated by a conventional Δ R2* map was also compared with the ΔSvO 2 estimated by QSM. Susceptibilities of five venous and tissue regions were quantified separately by QSM. Venous susceptibility was reduced by nearly 10%, with an SvO 2 shift of 10% during hyperoxia. A hyperoxic effect, confirmed by SpO 2 measurement, resulted in an SvO 2 increase in the cortex. The ΔSvO 2 between hyperoxia and normoxia was consistent with what was estimated by the Δ R2* map in five regions. These findings suggest that a quantitative susceptibility map is a promising technique for SvO 2 measurement. This method may be useful for quantitatively investigating oxygenation-dependent functional MRI studies. Magn Reson Med 77:592-602, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  9. Linear optical response of carbon nanotubes under axial magnetic field

    Science.gov (United States)

    Moradian, Rostam; Chegel, Raad; Behzad, Somayeh

    2010-04-01

    We considered single walled carbon naotubes (SWCNTs) as real three dimensional (3D) systems in a cylindrical coordinate. The optical matrix elements and linear susceptibility, χ(ω), in the tight binding approximation in terms of one-dimensional wave vector, kz and subband index, l are calculated. In an external axial magnetic field optical frequency dependence of linear susceptibility are investigated. We found that axial magnetic field has two effects on the imaginary part of the linear susceptibility spectrum, in agreement with experimental results. The first effect is broadening and the second, splitting. Also we found that for all metallic zigzag and armchair SWCNTs, the axial magnetic field leads to the creation of a peak with energy less than 1.5 eV, contrary to what is observed in the absence of a magnetic field.

  10. Investigations of the magnetic properties in the pyrochlore Ho{sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Schoenemann, Rico; Herrmannsdoerfer, Thomas; Green, Elizabeth Lauren; Wang, Zhaosheng; Wosnitza, Joachim [Dresden High Magnetic Field Laboratory, Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Skrotzki, Richard [Dresden High Magnetic Field Laboratory, Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Department of Chemistry and Food Chemistry, TU Dresden, Dresden (Germany); Kaneko, Hiroshi; Suzuki, Haruhiko [Faculty of Mathematics and Physics, Kanazawa University, Kanazawa (Japan)

    2013-07-01

    Pyrochlore compounds such as R{sub 2}Ti{sub 2}O{sub 7} (where R is Ho or Dy) have an highly degenerate ground state where the R{sup 3+} moments obey the ''ice rules''. This provides access to study extraordinary physical phenomena, like the formation of magnetic monopoles. Recent publications evidence monopoles which can be probed using high frequency (adiabatic) susceptibility measurements. We performed ac susceptibility measurements on a single-crystal Ho{sub 2}Ti{sub 2}O{sub 7} sample at low temperatures down to 30 mK and magnetic fields up to 14 T. Based on isothermal frequency sweeps we were able to determine spin relaxation rates. Both the real and imaginary parts of the temperature-dependent magnetic susceptibility measurements show the spins freezing below 1 K and provide insight into the magnetic-monopole density.

  11. Geophysical Modelling and Multi-Scale Studies in the Arctic Seiland Igneous Province: Millimeter to Micrometer Scale Mapping of the Magnetic Sources by High Resolution Magnetic Microscopy

    Science.gov (United States)

    Pastore, Z.; Church, N. S.; McEnroe, S. A.; Oda, H.; ter Maat, G. W.

    2017-12-01

    Rocks samples can have wide range of magnetic properties depending on composition, amount of ferromagnetic minerals, grain sizes and microstructures. These influence the magnetic anomalies from the micro to the global scale making the study of the magnetic properties of interest for multiple applications. Later geological processes such as serpentinization can significantly influence these properties and change the nature of the magnetic anomalies. Particularly, magnetic properties such as remanent magnetization and magnetic susceptibility are directly linked to the magnetic mineralogy composition and grain size and can provide useful information about the geological history of the source. Scanning magnetic microscopy is a highly sensitive and high-resolution magnetometric technique for mapping the magnetic field over a planar surface of a rock sample. The device measures the vertical component of the field above the thin sections and the technique offers a spatial resolution down to tens of micrometers and thus can be used to investigate discrete magnetic mineral grains or magnetic textures and structures, and the magnetic history of the sample. This technique allows a direct correlation between the mineral chemistry (through both electron and optical microscopy) and the magnetic properties. We present as case-study three thin section magnetic scans of two dunite samples from the Reinfjord Ultramafic complex, in northern Norway. The selected thin sections show different magnetic properties which reflect the magnetic petrology. One of the thin sections is from a pristine dunite sample; the other two are highly serpentinized with newly formed magnetite found in multiple, few micrometer thick, veins. We present the preliminary results obtained applying a forward modelling approach on the magnetic anomaly maps acquired over the thin sections. Modelling consists of uniformly-magnetized polygonal bodies whose geometry is constrained by the thickness of the thin section

  12. Magnetic Measurements of Atmospheric Dust Deposition in Soils

    Science.gov (United States)

    Kapička, Aleš; Petrovský, Eduard; Grison, Hana; Podrázský, Vilém; Křížek, Pavel

    2010-05-01

    Atmospheric dust of anthropogenic origin contains significant portion of minerals characterized by ferrimagnetic properties [1,2]. These minerals, mostly iron oxides, can serve as tracers of industrial pollutants in soil layers. Moreover, recent results, e.g., [3,4] show significant correlation between concentration-dependent magnetic parameters (e.g., low-field magnetic susceptibility) and concentration of heavy metals (e.g., Pb, Zn, Cd). In our paper we have investigated magnetic properties of depth soil profiles from Krušné hory Mountains (Czech Republic), which belong to a highly contaminated, so-called Black Triangle in central Europe. Emissions are determined by considerable concentration of big sources of pollution (power plants burning fossil fuel, metallurgical and chemical industry). Increased values of magnetic susceptibility (25 - 200 × 10-5 SI) were clearly identified in the top-soil layers. Thermomagnetic analyses and SEM observation indicate that the accumulated anthropogenic ferrimagnetics dominate these layers. Magnetic enhancement is limited to depths of 4-7 cm below the soil surface, usually in F-H or top of Ah soil horizons; deeper soil horizons contain mainly magnetically weak materials and are characterized by much lower values of susceptibility (up to 30 × 10-5 SI). Significant magnetic parameters (e.g., Curie temperature Tc) and SEM results of contaminated topsoils are comparable with magnetic parameters of atmospheric dust, collected (using high-volume samplers) at the same localities.

  13. Detecting atmospheric pollution in surface soils using magnetic measurements: A reappraisal using an England and Wales database

    International Nuclear Information System (INIS)

    Blundell, A.; Hannam, J.A.; Dearing, J.A.; Boyle, J.F.

    2009-01-01

    Industrial activity such as burning of fossil fuels produces magnetically enhanced particulates. These particulates consist of coarse-grained multidomain and stable single domain magnetic minerals. Two threshold values of low field magnetic susceptibility (χ LF ) and frequency dependent susceptibility percentage (χ FD %) discriminate ferrimagnetic minerals of these sizes and can act as a tracer of magnetic pollution. Application of the thresholds to a magnetic topsoil data set (n = 5656 across England and Wales) revealed 637 samples potentially dominated by pollution particulates. The magnetic parameters of these samples display a negative correlation with distance to urban areas and positive correlations with metals associated with anthropogenic activity (Cu, Pb, and Zn). Results of experimentation with threshold values and modelling of magnetic anomalies suggest that regional factors such as geology and potential for pedogenic secondary magnetic enhancement should be considered when setting threshold values. - An application of magnetic susceptibility and frequency dependent susceptibility thresholds across England and Wales to determine topsoil dominated by pollution derived particles.

  14. Nonlinear nuclear magnetic resonance in ferromagnets

    International Nuclear Information System (INIS)

    Nurgaliev, T.

    1988-01-01

    The properties of nonlinear nuclear magnetic resonance (NMR) have been studied theoretically by taking into account the interaction between NMR and FMR in the ferromagnets. The Landau-Lifshitz-Bloch equations, describing the electron and nuclear magnetization behaviour in ferromagnets are presented in an integral form for a weakly excited electronic system. The stationary solution of these equations has been analysed in the case of equal NMR and FMR frequencies: the criteria for the appearance of two stable dynamic states is found and the high-frequency magnetic susceptibility for these systems is investigated. 2 figs., 8 refs

  15. Magnetic interactions and magnetic anisotropy in exchange coupled 4f-3d systems: a case study of a heterodinuclear Ce3+-Fe3+ cyanide-bridged complex.

    Science.gov (United States)

    Sorace, Lorenzo; Sangregorio, Claudio; Figuerola, Albert; Benelli, Cristiano; Gatteschi, Dante

    2009-01-01

    We report here a detailed single-crystal EPR and magnetic study of a homologous series of complexes of the type Ln-M (Ln = La(III), Ce(III); M = Fe(III), Co(III)). We were able to obtain a detailed picture of the low-lying levels of Ce(III) and Fe(III) centres through the combined use of single-crystal EPR and magnetic susceptibility data. We show that classical ligand field theory can be of great help in rationalising the energies of the low-lying levels of both the transition-metal and rare-earth ions. The combined analysis of single-crystal EPR and magnetic data of the coupled system Ce-Fe confirmed the great complexity of the interactions involving rare-earth elements. With little uncertainty, it turned out clearly that the description of the interaction involving the lowest lying spin levels requires the introduction of the isotropic, anisotropic and antisymmetric terms.

  16. [Blood detoxification using superparamagnetic nanoparticles (magnetic hemodialysis)].

    Science.gov (United States)

    Ciochină, Al D; Untu, Alina; Iacob, Gh

    2010-01-01

    The authors present an experimental study realized in order to simulate blood detoxification with the help of supermagnetic nanoparticles. The particles used are red oxide nanoparticles which are considered to be equivalent from a magnetic susceptibility and dynamic diameter point of view to the complex structures of magnetite nanoparticles. Two types of custom HGMS matrices have been used--a threaded one and a micro-spheres one. For testing red oxide particles have been purposefully created to have a lower magnetic susceptibility than magnetite or iron-carbon particles used in other experimental studies. Different concentrations of iron oxide, glycerine and water have been prepared, creating a 3.5 cP viscosity (equivalent to the one of the blood); the concentrations of the prepared solutions varied between 0.16 mg/mL and 2 mg/mL, with the background magnetic field value ranging from 0.25 T to 0.9 T, in order to observer the effectiveness of filtering at different intensities. The efficiency of HGMS filtering in experimental conditions was almost completely successful (99.99%) in all experimental conditions, both with the threaded and micro-spheres matrices. The high gradient magnetic separation system of nanoparticles has maximum efficiency and has the potential of being implemented in a medical blood detoxification device.

  17. Solid-liquid transition in Nb powder determined by third harmonic susceptibility

    International Nuclear Information System (INIS)

    Oliveira, A.A.M.; Lisboa-Filho, P.N.; Ortiz, W.A.

    2008-01-01

    Measurements of the third harmonic of the AC-susceptibility were employed to determine the boundaries of the linear regime of the magnetic response of Nb powder. Non-linear contributions to the magnetic response reveal the occurrence of a structured phase, disappearing as the vortex lattice melts to the liquid state. A systematic study of the third harmonic was conducted to determine how its onset temperature depends on experimental parameters, such as the frequency and amplitude of the excitation field. The melting line (ML) has been extracted from the onset temperature measured at low-frequencies and low-excitation fields in the presence of DC magnetic fields. The study indicates that the ML can be described by a 3D vortex-glass model, except at lower fields, where the system experiences a depinning crossover, and the best description of the experimental data is provided by a 3D Bose-glass model

  18. Solid-liquid transition in Nb powder determined by third harmonic susceptibility

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, A.A.M. [Grupo de Supercondutividade e Magnetismo, Departamento de Fisica, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil)], E-mail: ana@df.ufscar.br; Lisboa-Filho, P.N. [Laboratorio de Materiais Supercondutores, Departamento de Fisica, Universidade Estadual Paulista, Bauru, SP (Brazil); Ortiz, W.A. [Grupo de Supercondutividade e Magnetismo, Departamento de Fisica, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil)

    2008-07-15

    Measurements of the third harmonic of the AC-susceptibility were employed to determine the boundaries of the linear regime of the magnetic response of Nb powder. Non-linear contributions to the magnetic response reveal the occurrence of a structured phase, disappearing as the vortex lattice melts to the liquid state. A systematic study of the third harmonic was conducted to determine how its onset temperature depends on experimental parameters, such as the frequency and amplitude of the excitation field. The melting line (ML) has been extracted from the onset temperature measured at low-frequencies and low-excitation fields in the presence of DC magnetic fields. The study indicates that the ML can be described by a 3D vortex-glass model, except at lower fields, where the system experiences a depinning crossover, and the best description of the experimental data is provided by a 3D Bose-glass model.

  19. Geochemistry and Cyclostratigraphy of Magnetic Susceptibility data from the Frasnian-Famennian event interval in western Canada: Insights in the pattern and timing of a biotic crisis

    Science.gov (United States)

    Whalen, M. T.; De Vleeschouwer, D.; Sliwinski, M. G.; Claeys, P. F.; Day, J. E.

    2012-12-01

    during a single short eccentricity cycle (100 ky) while the UKE was more protracted, lasting approximately two short eccentricity cycles (200 ky). This work demonstrates the utility of long time series of magnetic susceptibility data used in conjunction with other multi-proxy data to provide insight into events in geologic time. These results corroborate earlier studies that pointed out fundamental differences in the LKE and UKE wherein the LKE appears to be related to relatively rapid climate and sea level change whereas the UKE seems to be related to more protracted climatic cooling associated with the beginning of an icehouse climate.

  20. Environmental magnetism and effective radium concentration: the case study of the painted cave of Pech Merle, France

    Science.gov (United States)

    Isambert, Aude; Girault, Frédéric; Perrier, Frédéric; Bouquerel, Hélène; Bourges, François

    2017-04-01

    Painted caves, showing testimony of prehistoric art, are nowadays subject to intense attention to understand the conditions of stability and avoid degradation. The preservation of cultural sequences and archaeological artefacts represents especially a crucial issue in the case of caves opened to visitors. For this purpose, a better knowledge of these preserved environments that imprint paleoenvironmental conditions at the time of deposition is needed. In this context, different environmental parameters of the Pech Merle cave, in France, are currently actively monitored including temperature, hygrometry, and gas measurements such as CO2 and radon-222 (decay product of radium-226). This temporal monitoring needs to be complemented by a detailed characterisation of the site, including petrophysical and mineralogical properties. To better constrain the environmental and paleoenvironmental context, more than 100 samples including soils, sediments, rocks and speleothems were collected inside and outside the cave area. We report here magnetic properties of powdered samples (low-field susceptibility, hysteresis parameters, and saturation magnetization) coupled with effective radium concentration (ECRa) measurements. We observe that magnetic susceptibility, which ranges over 5 orders of magnitude from calcareous rocks to topsoils and argillaceous filling deposits, correlates well with ECRa values. This correlation, previously observed (Girault et al., 2016) in very different geological contexts, could be interpreted as a common concentration of sources, also indicating a signature of natural samples to the contrary of anthropic environments disturbed by human activities, in which case the association is blurred. This study demonstrates the general interest of combining two different parameters - here low-field magnetic susceptibility and effective radium concentration determined using non-destructive techniques in the field and in the laboratory - to physically characterize

  1. Complex Susceptibility Measurement Using Multi-frequency Slingram EMI Instrument

    OpenAIRE

    Simon , François Xavier; Tabbagh , Alain; Thiesson , Julien; Donati , J.C.; Sarris , A.

    2014-01-01

    International audience; Complex magnetic susceptibility is a well-known property both theoretically and experimentally. To achieve this measurement, different ways have been tested, like TDEM or multi-frequential measurement on soil sample. In this study we carry out the measurements by the use of a multi-frequential EMI Slingram instrument to collect data quickly and in-situ. The use of multi-frequency data is also a way to correct effects of the conductivity on the in-phase component and ef...

  2. Magnetic-superexchange interactions of uranium(IV) chloride-addition complexes with amides, 2

    International Nuclear Information System (INIS)

    Miyake, Chie; Hinatsu, Yukio; Imoto, Shosuke

    1983-01-01

    The magnetic susceptibilities of five cyclic amide (lactam)-addition complexes of uranium(IV) chloride were measured between room temperature and 2 K. Magnetic-exchange interaction was found only for N-methyl-substituted amide complexes, and a dimer structure was assumed for them on the basis of their chemical properties. Treating interdimer interaction with a molecular-field approximation, the magnetic susceptibilities were calculated to be in good agreement with the experimental results in the temperature region of the maxima in chi sub(A). The transmission of antiparallel spin coupling via the π orbitals of the bridging amide ligands is proposed to explain the strong intradimer superexchange interaction for the uranium(IV) chloride-amide complexes with the magnetic-susceptibility maximum. (author)

  3. Mineral magnetism of atmospheric dust over southwest coast of India: Impact of anthropogenic activities and implications to public health

    Science.gov (United States)

    Warrier, Anish Kumar; Shankar, R.; Manjunatha, B. R.; Harshavardhana, B. G.

    2014-03-01

    We have used rock magnetic techniques in this study to assess atmospheric pollution at five stations in and around Mangalore city on the southwestern coast of India. Samples of dust were collected from two suburban areas (Thokkottu and Pumpwell located respectively ~ 10 km and 3 km from the city center), the city center itself (Milagres) and industrial/port areas (Panambur and Mangalore Refinery and Petrochemicals Limited (MRPL)). Low-frequency magnetic susceptibility (χlf), frequency-dependent susceptibility (χfd), susceptibility of anhysteretic remanent magnetization (χARM) and isothermal remanent magnetization (IRM 20 to 1000 mT) were determined on 23 dust samples and inter-parametric ratios calculated. Results show that samples from suburban areas (particularly Thokkottu) are characterized by low χlf (Company Limited (KIOCL) at Panambur and its storage and export through the nearby New Mangalore Port. However, the dust sample from MRPL has magnetically "soft" minerals like magnetite. This magnetic mineral may have originated from petroleum refining processes at MRPL. Particulate pollution from industrial activities and motor vehicle exhaust is a threat to human health and is known to cause cardiovascular and respiratory ailments. Therefore, the pollution levels brought out by this study warrant a comprehensive epidemiological study in the area of study.

  4. Dielectric and diamagnetic susceptibilities near percolative superconductor-insulator transitions.

    Science.gov (United States)

    Loh, Yen Lee; Karki, Pragalv

    2017-10-25

    Coarse-grained superconductor-insulator composites exhibit a superconductor-insulator transition governed by classical percolation, which should be describable by networks of inductors and capacitors. We study several classes of random inductor-capacitor networks on square lattices. We present a unifying framework for defining electric and magnetic response functions, and we extend the Frank-Lobb bond-propagation algorithm to compute these quantities by network reduction. We confirm that the superfluid stiffness scales approximately as [Formula: see text] as the superconducting bond fraction p approaches the percolation threshold p c . We find that the diamagnetic susceptibility scales as [Formula: see text] below percolation, and as [Formula: see text] above percolation. For models lacking self-capacitances, the electric susceptibility scales as [Formula: see text]. Including a self-capacitance on each node changes the critical behavior to approximately [Formula: see text].

  5. Magnetic and elastic properties of the antiferromagnet uranium mononitride

    International Nuclear Information System (INIS)

    Van Doorn, C.F.

    1976-10-01

    The magnetic and elastic properties of antiferromagnetic uranium mononitride single crystals are studied in the thesis from the measurements of the temperature dependences of the magnetic susceptibility, electrical resistivity and elastic constants. The elastic constants C 11 , C 12 and C 44 were determined in the temperature interval 4 to 300 K by ultrasonic measurements of the five possible wave velocities in the [100] and [110] directions. A test for internal consistency was also made. A dip of about 9 percent occurs in C 11 at a temperature of 5 to 6 K lower than the Neel temperature T(N) (equals about 53 K). Starting at T(N), a renormalization in C 44 is proportional to the square of the sublattice magnetization also occurs. Both these results agree with model calculations which include spin-phonon interactions. The investigation of this anomaly was extended by measuring the electrical resistivity of a sample cut from the same crystal as that on which the elasticity was measured. No anomalous behavior was observed at the temperature where C 11 displays its anomaly. However, a discontinuity in the temperature derivative of the resistance was found at T(N). The possible effect of a magnetic field on the resistivity, as well as on the elasticity, was investigated without any measurable effect. The magnetic susceptibility was measured with a Foner magnetometer between 4 and 1 000 K. It was found that above the Neel temperature the paramagnetic susceptibility followed a revised Curie-Weiss law. In an attempt to ascertain the ionic state of the 5f-uranium ion in UN, use was made of the experimentally determined Weiss constant, spin disorder resistivity and Knight shift. A calculation was made that gave a good representation of the ratio of the experimental susceptibilities along the [100] and [110] directions in the ordered region [af

  6. Synthesis, characterization and a.c. magnetic analysis of magnetite nanoparticles

    International Nuclear Information System (INIS)

    Riani, P.; Napoletano, M.; Canepa, F.

    2011-01-01

    In the last years, the study of Fe-based magnetic nanoparticles (MNP) has attracted increasing interest either for the physical properties shown by nanosized materials (electric and magnetic properties are strongly affected by dimension and surface effects) either for the different technological applications of these materials (catalysis, drug delivery, magnetic resonance imaging, contaminants removal from groundwater, new exchange coupled magnets, soft nanomagnets for high frequency applications, etc.). In this article, the results obtained in the synthesis and characterization of the Fe 3 O 4 MNP is reported. The magnetite nanoparticles were synthesized by a modified Massart method. Structural characterization was performed using X-ray diffraction analysis and a complete morphological and dimensional study was carried out by means of Transmission Electron Microscopy, and a.c. magnetic susceptibility measured as a function of the frequency of the applied magnetic field. Diameters of the superparamagnetic Fe 3 O 4 nanoparticles are ranging from 2 to 10 nm, as evidenced by all the techniques employed. The size distribution of the hydrated aggregates in solution has been obtained by quantitative analysis of the frequency dependence of the a.c. susceptibility. The mathematical approach adopted will be described and all the obtained results will be compared and discussed.

  7. Temperature-dependent magnetic properties of a magnetoactive elastomer: Immobilization of the soft-magnetic filler

    Science.gov (United States)

    Bodnaruk, Andrii V.; Brunhuber, Alexander; Kalita, Viktor M.; Kulyk, Mykola M.; Snarskii, Andrei A.; Lozenko, Albert F.; Ryabchenko, Sergey M.; Shamonin, Mikhail

    2018-03-01

    The magnetic properties of a magnetoactive elastomer (MAE) filled with μm-sized soft-magnetic iron particles have been experimentally studied in the temperature range between 150 K and 310 K. By changing the temperature, the elastic modulus of the elastomer matrix was modified, and it was possible to obtain magnetization curves for an invariable arrangement of particles in the sample and in the case when the particles were able to change their position within the MAE under the influence of magnetic forces. At low (less than 220 K) temperatures, when the matrix becomes rigid, the magnetization of the MAE does not show a hysteresis behavior, and it is characterized by a negative value of the Rayleigh constant. At room temperature, when the polymer matrix is compliant, a magnetic hysteresis exists where the dependence of the differential magnetic susceptibility on the magnetic field exhibits local maxima. The appearance of these maxima is explained by the elastic resistance of the matrix to the displacement of particles under the action of magnetic forces.

  8. An ac susceptibility study in capped Ni/Ni(OH)2 core-shell nanoassemblies: dual peak observations

    International Nuclear Information System (INIS)

    Godsell, Jeffrey F; Roy, Saibal; Bala, Tanushree; Ryan, Kevin M.

    2011-01-01

    In this study, the ac susceptibility (χ' and χ'') variation with temperature (10-100 K) for oleic acid (OA) capped Ni/Ni(OH) 2 core-shell nanoparticle assemblies are reported at frequencies varying from 0.1 to 1000 Hz. Nanoparticle assemblies, with two average particle diameters of ∼34 nm and ∼14 nm, were synthesized using a wet chemical synthesis approach. Two peaks in the ac susceptibility versus temperature curves are clearly discernable for each of the samples. The first, occurring at ∼22 K was attributed to the paramagnetic/antiferromagnetic transition of the Ni(OH) 2 present in the shell. The second higher temperature peak was attributed to the superparamagnetic blocking of the pure Ni situated at the core of the nanoparticles. The higher temperature peaks in both the χ' and χ'' curves were observed to increase with increasing frequency. Thus the Neel and the blocking temperatures for such core-shell nanoassemblies were clearly identified from the ac analysis, whereas they were not discernible (superimposed) even from very low dc (FC/ZFC) field measurements. Interparticle interactions within the assemblies were studied through the fitting of phenomenological laws to the experimental datasets. It is observed that even with an OA capping layer, larger Ni/Ni(OH) 2 nanoparticles experience a greater degree of sub-capping layer oxidation thus producing lower magnetic interaction strengths.

  9. The Theory of the Reentrant Effect in Susceptibility of Cylindrical Mesoscopic Samples

    International Nuclear Information System (INIS)

    Gogadze, G.A.

    2006-01-01

    A theory has been developed to explain the anomalous behavior of the magnetic susceptibility of a normal metal-superconductor (NS) structure in weak magnetic fields at milli kelvin temperatures. The effect was discovered experimentally [A. C. Mota et al., Phys. Rev. Lett. 65, 1514 (1990)]. In cylindrical superconducting samples covered with a thin normal pure metal layer, the susceptibility exhibited a reentrant effect: it started to increase unexpectedly when the temperature was lowered below 100 mK. The effect was observed in mesoscopic NS structures when the N and S metals were in good electric contact. The theory proposed is essentially based on the properties of the Andreev levels in the normal metal. When the magnetic field (or temperature) changes, each of the Andreev levels coincides from time to time with the chemical potential of the metal. As a result, the state of the NS structure experiences strong degeneracy, and the quasiparticle density of states exhibits resonance spikes. This generates a large paramagnetic contribution to the susceptibility, which adds to the diamagnetic contribution, thus leading to the reentrant effect. The explanation proposed was obtained within the model of free electrons. The theory provides a good description of the experimental results

  10. The magnetic structures and the magnetic phase diagram of the TbMn{sub 2}(Ge,Si){sub 2} system

    Energy Technology Data Exchange (ETDEWEB)

    Granovsky, S.A. [Department of Physics, M.V. Lomonosov Moscow State University, GSP-2, 119992 Moscow (Russian Federation) and TU Dresden, Institut fuer Festkoerperphysik, D-01062, Dresden (Germany)]. E-mail: ser@plms.phys.msu.ru; Gaidukova, I.Yu. [Department of Physics, M.V. Lomonosov Moscow State University, GSP-2, 119992 Moscow (Russian Federation); Doerr, M. [TU Dresden, Institut fuer Festkoerperphysik, D-01062, Dresden (Germany); Loewenhaupt, M. [TU Dresden, Institut fuer Festkoerperphysik, D-01062, Dresden (Germany); Markosyan, A.S. [Department of Physics, M.V. Lomonosov Moscow State University, GSP-2, 119992 Moscow (Russian Federation); State Center for Condensed Matter Physics, Rogova str.5., 123060 Moscow (Russian Federation); Ritter, C. [Institut Laue-Langevin, 38042 Grenoble Cedex 9 (France)

    2007-03-15

    Magnetic structures and magnetic phase transitions in natural-layered TbMn{sub 2}(Ge {sub x} Si{sub 1-} {sub x} ){sub 2} compounds have been studied by magnetisation, low-field AC-susceptibility, electrical resistivity and neutron-diffraction experiments. Non-collinear magnetic structures were observed in the concentration range 0 magnetic x-T phase diagram of the TbMn{sub 2}(Ge {sub x} Si{sub 1-} {sub x} ){sub 2} system is constructed and the role of magnetic couplings of different type for the stabilisation of the various magnetic structures is discussed.

  11. Analysis of critical state response in thin films by AC susceptibility measurements

    Czech Academy of Sciences Publication Activity Database

    Youssef, A.; Švindrych, Z.; Hadač, J.; Janů, Zdeněk

    2008-01-01

    Roč. 18, č. 2 (2008), s. 1589-1592 ISSN 1051-8223 R&D Projects: GA ČR GA102/05/0942 Institutional research plan: CEZ:AV0Z10100520 Keywords : AC susceptibility * critical state * harmonics * thin film * axial magnetic-field * superconductor disks * cylinders Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.919, year: 2008

  12. Magnetic response of superconducting mesoscopic-size YBCO powder

    Energy Technology Data Exchange (ETDEWEB)

    Deimling, C.V. [Grupo de Supercondutividade e Magnetismo, Departamento de Fisica, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil)], E-mail: cesard@df.ufscar.br; Motta, M.; Lisboa-Filho, P.N. [Laboratorio de Materiais Supercondutores, Departamento de Fisica, Universidade Estadual Paulista, Bauru, SP Brazil (Brazil); Ortiz, W.A. [Grupo de Supercondutividade e Magnetismo, Departamento de Fisica, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil)

    2008-07-15

    In this work it is reported the magnetic behavior of submicron and mesoscopic-size superconducting YBCO powders, prepared by a modified polymeric precursors method. The grain size and microstructure were analyzed using scanning electron microscopy (SEM). Measurements of magnetization and AC-susceptibility as a function of temperature were performed with a quantum design SQUID magnetometer. Our results indicated significant differences on the magnetic propreties, in connection with the calcination temperature and the pressure used to pelletize the samples. This contribution is part of an effort to study vortex dynamics and magnetic properties of submicron and mesoscopic-size superconducting samples.

  13. Moessbauer and magnetic investigation of Fe-Mn alloy

    International Nuclear Information System (INIS)

    Yousif, A.A.

    1994-01-01

    Moessbauer, X-ray, magnetization and susceptibility measurements were performed to study Fe 100-x Mn x , x = 5, 15, 39, 50. The different phases of Fe-Mn were identified, and hyperfine interaction parameters and average magnetic moments of some samples were determined. The average hyperfine field and average magnetic moment decrease as x increases. The influence of the Mn neighbourhood on the derived parameters is discussed in the light of calculations using the first principle discrete variational method in the local density approximation. (orig.)

  14. 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

  15. Method of magnetic separation and apparatus therefore

    Science.gov (United States)

    Oder, Robin R. (Inventor)

    1991-01-01

    An apparatus for magnetically separating and collecting particulate matter fractions of a raw sample according to relative magnetic susceptibilities of each fraction so collected is disclosed. The separation apparatus includes a splitter which is used in conjunction with a magnetic separator for achieving the desired fractionation.

  16. New Mn(II, Ni(II, Cd(II, Pb(II complexes with 2-methylbenzimidazole and other ligands. Synthesis, spectroscopic characterization, crystal structure, magnetic susceptibility and biological activity studies

    Directory of Open Access Journals (Sweden)

    Shayma A. Shaker

    2016-11-01

    Full Text Available Synthesis and characterization of Mn(II, Ni(II, Cd(II and Pb(II mixed ligand complexes of 2-methylbenzimidazole with other ligands have been reported. The structure of the ligands and their complexes was investigated using elemental analysis, IR, UV–Vis, (1H, 13C NMR spectroscopy, molar conductivity and magnetic susceptibility measurements. In all the studies of complexes, the 2-methylbenzimidazole behaves as a neutral monodentate ligand which is coordinated with the metal ions through the N atom. While benzotriazole behaves as a neutral bidentate ligand which is coordinated with the Ni(II ion through the two N atoms. Moreover, the N-acetylglycine behaves as a bidentate ligand which is coordinated with the Mn(II, Ni(II and Pb(II ions through the N atom and the terminal carboxyl oxygen atom. The magnetic and spectral data indicate the tetrahedral geometry for Mn(II complex, irregular tetrahedral geometry for Pb(II complex and octahedral geometry for Ni(II complex. The X-ray single crystal diffraction method was used to confirm a centrosymmetric dinuclear Cd(II complex as each two metal ions are linked by a pair of thiocyanate N = S bridge. Two 2-methylbenzimidazole N-atom donors and one terminal thiocyanate N atom complete a highly distorted square pyramid geometry around the Cd atom. Besides, different cell types were used to determine the inhibitory effect of Mn(II, Ni(II, Cd(II and Pb(II complexes on cell growth using MTT assay. Cd(II complex showed cytotoxic effect on various types of cancer cell lines with different EC50 values.

  17. Magnetic properties of a URhSi single crystal

    Czech Academy of Sciences Publication Activity Database

    Honda, F.; Andreev, Alexander V.; Sechovský, V.; Prokeš, K.

    329-333, - (2003), s. 486-488 ISSN 0921-4526 R&D Projects: GA ČR GA202/02/0739 Keywords : URhSi * magnetization * magnetic susceptibility * specific heat Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.908, year: 2003

  18. Magnetic resonance imaging susceptibility artifacts in the cervical vertebrae and spinal cord related to monocortical screw-polymethylmethacrylate implants in canine cadavers.

    Science.gov (United States)

    Jones, Brian G; Fosgate, Geoffrey T; Green, Eric M; Habing, Amy M; Hettlich, Bianca F

    2017-04-01

    OBJECTIVE To characterize and compare MRI susceptibility artifacts related to titanium and stainless steel monocortical screws in the cervical vertebrae and spinal cord of canine cadavers. SAMPLE 12 canine cadavers. PROCEDURES Cervical vertebrae (C4 and C5) were surgically stabilized with titanium or stainless steel monocortical screws and polymethylmethacrylate. Routine T1-weighted, T2-weighted, and short tau inversion recovery sequences were performed at 3.0 T. Magnetic susceptibility artifacts in 20 regions of interest (ROIs) across 4 contiguous vertebrae (C3 through C6) were scored by use of an established scoring system. RESULTS Artifact scores for stainless steel screws were significantly greater than scores for titanium screws at 18 of 20 ROIs. Artifact scores for titanium screws were significantly higher for spinal cord ROIs within the implanted vertebrae. Artifact scores for stainless steel screws at C3 were significantly less than at the other 3 cervical vertebrae. CONCLUSIONS AND CLINICAL RELEVANCE Evaluation of routine MRI sequences obtained at 3.0 T revealed that susceptibility artifacts related to titanium monocortical screws were considered mild and should not hinder the overall clinical assessment of the cervical vertebrae and spinal cord. However, mild focal artifacts may obscure small portions of the spinal cord or intervertebral discs immediately adjacent to titanium screws. Severe artifacts related to stainless steel screws were more likely to result in routine MRI sequences being nondiagnostic; however, artifacts may be mitigated by implant positioning.

  19. Phase separation and magnetic ordering studied by high resolution neutron diffraction

    International Nuclear Information System (INIS)

    Caspi, E.N.; Melamud, M.; Pinto, H.; Shaked, H.; Chmaissem, O.; Jorgensen, J.D.; Short, S.

    1999-01-01

    Complete text of publication follows. In a previous work on the (U 1-x Nd x )Co 2 Ge 2 system, two magnetic transitions were observed in the temperature dependencies of the magnetic susceptibility and in the intensity of the magnetic reflections in neutron diffraction [1]. Because of insufficient resolution, it was not clear whether this is due to clustering or phase separation. In both cases the U-rich regions are expected to order magnetically at higher temperature than the U-poor ones, resulting in two magnetic transitions. In order to resolve this question a temperature dependent TOF neutron diffraction of the x = 0.25 compound has been performed on the SEPD at Argonne's IPNS [2]. The temperature dependent diffractograms were refined by the Rietveld method. It was found that the compound separates into two phases: x = 0.4 (55 wt%) and x = 0.1 (45 wt%). The temperature dependence of the magnetic moment was obtained for each phase, with the transition temperatures: T N (x=0.4) = 130 K, and T N (x=0.1) = 165 K. (author) [1] E. Caspi et al., Phys. Rev. B, 57 (198) 449.; [2] J.D. Jorgensen et al., J. Appl. Cryst. 22 (1989) 321

  20. Time-course assessment of the aggregation and metabolization of magnetic nanoparticles.

    Science.gov (United States)

    Rojas, José M; Gavilán, Helena; Del Dedo, Vanesa; Lorente-Sorolla, Eduardo; Sanz-Ortega, Laura; da Silva, Gustavo B; Costo, Rocío; Perez-Yagüe, Sonia; Talelli, Marina; Marciello, Marzia; Morales, M Puerto; Barber, Domingo F; Gutiérrez, Lucía

    2017-08-01

    To successfully develop biomedical applications for magnetic nanoparticles, it is imperative that these nanoreagents maintain their magnetic properties in vivo and that their by-products are safely metabolized. When placed in biological milieu or internalized into cells, nanoparticle aggregation degree can increase which could affect magnetic properties and metabolization. To evaluate these aggregation effects, we synthesized citric acid-coated iron oxide nanoparticles whose magnetic susceptibility can be modified by aggregation in agar dilutions and dextran-layered counterparts that maintain their magnetic properties unchanged. Macrophage models were used for in vitro uptake and metabolization studies, as these cells control iron homeostasis in the organism. Electron microscopy and magnetic susceptibility studies revealed a cellular mechanism of nanoparticle degradation, in which a small fraction of the particles is rapidly degraded while the remaining ones maintain their size. Both nanoparticle types produced similar iron metabolic profiles but these profiles differed in each macrophage model. Thus, nanoparticles induced iron responses that depended on macrophage programming. In vivo studies showed that nanoparticles susceptible to changes in magnetic properties through aggregation effects had different behavior in lungs, liver and spleen. Liver ferritin levels increased in these animals showing that nanoparticles are degraded and their by-products incorporated into normal metabolic routes. These data show that nanoparticle iron metabolization depends on cell type and highlight the necessity to assess nanoparticle aggregation in complex biological systems to develop effective in vivo biomedical applications. Magnetic iron oxide nanoparticles have great potential for biomedical applications. It is however imperative that these nanoreagents preserve their magnetic properties once inoculated, and that their degradation products can be eliminated. When placed in a