WorldWideScience

Sample records for susceptibility magnetic

  1. Magnetic susceptibilities of minerals

    Science.gov (United States)

    Rosenblum, Sam; Brownfield, I.K.

    2000-01-01

    Magnetic separation of minerals is a topic that is seldom reported in the literature for two reasons. First, separation data generally are byproducts of other projects; and second, this study requires a large amount of patience and is unusually tedious. Indeed, we suspect that most minerals probably are never investigated for this property. These data are timesaving for mineralogists who concentrate mono-mineralic fractions for chemical analysis, age dating, and for other purposes. The data can certainly be used in the ore-beneficiation industries. In some instances, magnetic-susceptibility data may help in mineral identification, where other information is insufficient. In past studies of magnetic separation of minerals, (Gaudin and Spedden, 1943; Tille and Kirkpatrick, 1956; Rosenblum, 1958; Rubinstein and others, 1958; Flinter, 1959; Hess, 1959; Baker, 1962; Meric and Peyre, 1963; Rojas and others, 1965; and Duchesne, 1966), the emphasis has been on the ferromagnetic and paramagnetic ranges of extraction. For readers interested in the history of magnetic separation of minerals, Krumbein and Pettijohn (1938, p. 344-346) indicated nine references back to 1848. The primary purpose of this paper is to report the magnetic-susceptibility data on as many minerals as possible, similar to tables of hardness, specific gravity, refractive indices, and other basic physical properties of minerals. A secondary purpose is to demonstrate that the total and best extraction ranges are influenced by the chemistry of the minerals. The following notes are offered to help avoid problems in separating a desired mineral concentrate from mixtures of mineral grains.

  2. 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

  3. 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

  4. 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.

  5. Frequency dependence of magnetic susceptibility of weakly ...

    African Journals Online (AJOL)

    This paper reports the frequency dependence of magnetic susceptibility of weakly contaminated soil sediments. Low field magnetic susceptibility measurements were carried out on soil sediments at Bomo irrigation dam, Samaru College of Agriculture, Ahmadu Bello University, (ABU), Zaria, using the MS2D field loop.

  6. 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.

  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. 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.

  9. 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

  10. 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

  11. 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

  12. Anisotropy of the magnetic susceptibility of gallium

    Science.gov (United States)

    Pankey, T.

    1960-01-01

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

  13. 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

  14. Nonlinear susceptibility magnitude imaging of magnetic nanoparticles

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  15. Determination of magnetic susceptibility of sedimentation rock in Java island

    International Nuclear Information System (INIS)

    Rahmawati; Rauf, Nurlela; Bijaksana, Satria

    2002-01-01

    Determination of magnetic susceptibility of sedimentation rock in java island. It has been done a research on detemlination of magnetic susceptibility of sedimentation and intrusion rock. A simple magnetic separation method was used to separate material with high contain magnetic mineral from the low contain magnetic mineral. Besides a data measurement from magnetic susceptibility and intensity there are also X-ray diffraction data available as suppolling data. The result shown that every material has magnetic mineral In it with different contain. And sedimentation rock has higher magnetic mineral than the intrusion rock

  16. Analysis of MR Image in the Measurement of Magnetic Susceptibility

    Czech Academy of Sciences Publication Activity Database

    Bartušek, Karel; Gescheidtová, E.; Smékal, Z.

    2006-01-01

    Roč. 8, č. 1 (2006), 4203:17-26 ISSN 1738-9682 Institutional research plan: CEZ:AV0Z20650511 Keywords : magnetic resonance * magnetic susceptibility * MR image * tomographic scanner Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  17. 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 ...

  18. 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.

  19. 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.

  20. MR measurement of alloy magnetic susceptibility: towards developing tissue-susceptibility matched metals.

    Science.gov (United States)

    Astary, Garrett W; Peprah, Marcus K; Fisher, Charles R; Stewart, Rachel L; Carney, Paul R; Sarntinoranont, Malisa; Meisel, Mark W; Manuel, Michele V; Mareci, Thomas H

    2013-08-01

    Magnetic resonance imaging (MRI) can be used to relate structure to function mapped with high-temporal resolution electrophysiological recordings using metal electrodes. Additionally, MRI may be used to guide the placement of electrodes or conductive cannula in the brain. However, the magnetic susceptibility mismatch between implanted metals and surrounding brain tissue can severely distort MR images and spectra, particularly in high magnetic fields. In this study, we present a modified MR method of characterizing the magnetic susceptibility of materials that can be used to develop biocompatible, metal alloys that match the susceptibility of host tissue in order to eliminate MR distortions proximal to the implant. This method was applied at 4.7T and 11.1T to measure the susceptibility of a model solid-solution alloy of Cu and Sn, which is inexpensive but not biocompatible. MR-derived relative susceptibility values of four different compositions of Cu-Sn alloy deviated by less than 3.1% from SQUID magnetometry absolute susceptibility measurements performed up to 7T. These results demonstrate that the magnetic susceptibility varies linearly with atomic percentage in these solid-solution alloys, but are not simply the weighted average of Cu and Sn magnetic susceptibilities. Therefore susceptibility measurements are necessary when developing susceptibility-matched, solid-solution alloys for the elimination of susceptibility artifacts in MR. This MR method does not require any specialized equipment and is free of geometrical constraints, such as sample shape requirements associated with SQUID magnetometry, so the method can be used at all stages of fabrication to guide the development of a susceptibility matched, biocompatible device. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Topsoil magnetic susceptibility mapping: data reproducibility and compatibility, measurement strategy

    Czech Academy of Sciences Publication Activity Database

    Schibler, L.; Boyko, T.; Ferdyn, M.; Gajda, B.; Höll, S.; Jordanova, Neli; Rösler, W.

    2002-01-01

    Roč. 46, č. 1 (2002), s. 43-57 ISSN 0039-3169 Grant - others:EU 5FP RTD Project MAGPROX(XE) No.EVK2-CT-1999-00019 Institutional research plan: CEZ:AV0Z3012916 Keywords : soil magnetism * industrial pollution * magnetic susceptibility Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.571, year: 2002

  2. The influence of soil moisture on magnetic susceptibility measurements

    Science.gov (United States)

    Maier, G.; Scholger, R.; Schön, J.

    2006-06-01

    An important methodological question for magnetic susceptibility measurements is if a variation of the soil conductivity, as a result of a change in soil moisture, influences the measured susceptibility values. An answer to this question is essential because an accurate magnetic susceptibility mapping requires a grid of comparable magnetic susceptibility values, which indicate the magnetic iron-mineral contents of the soils. Therefore, in the framework of the MAGPROX project (EU-Project EVK2-CT-1999-00019), the study aims at investigating the influence of soil moisture and the possible correlation between magnetic susceptibility and electric conductivity. This approach was realised by model experiments in the laboratory and a field monitoring experiment, which was performed in an analogical manner as the model. For the laboratory experiment, a plastic tub with a water in- and outflow system and installed lines of electrodes was used. The measurements were carried out with layers of different magnetic material within the experimental sand formation under varying water saturation conditions. For the field experiment, which was carried out from July to December 2003, two test sites were selected. The magnetic susceptibility was measured by means of the recently developed vertical soil profile kappa meter SM400 and a commonly used Bartington MS2D probe. The electric resistivity was recorded using a 4-point light system (laboratory) and a ground conductivity meter EM38 (field). The knowledge of the resistivity of the sand formation enabled an estimation of porosity and water saturation in consideration of the Archie equations. The laboratory experiment results showed a very slight variation of measured magnetic susceptibility under different degrees of moisture, indicating mainly the influence from the diamagnetic contribution of the water volume. A measurement error in connection with the measurement method, for example caused by an interfering effect of soil

  3. 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.

  4. 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)

  5. 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?

  6. 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?

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

    Indian Academy of Sciences (India)

    Oriented samples of sediments from Ariyalur Group, Cauvery Basin, south India, were studied for low field anisotropy of magnetic susceptibility (AMS) measurements to unravel the magnetic fabrics and pale- ocurrent directions. The results of AMS parameters of the sediments indicate primary depositional fabrics.

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

    Indian Academy of Sciences (India)

    Oriented samples of sediments from Ariyalur Group, Cauvery Basin, south India, were studied for low field anisotropy of magnetic susceptibility (AMS) measurements to unravel the magnetic fabrics and paleocurrent directions. The results of AMS parameters of the sediments indicate primary depositional fabrics for Sillakkudi ...

  9. A simple and accurate relative alternative magnetic susceptibility measurement technique

    Energy Technology Data Exchange (ETDEWEB)

    Zawilski, B.M., E-mail: zawilski@grenoble.cnrs.f [Institut Neel-MCMF--CNRS-UJF 25, Rue des Martyrs, F 38042 Grenoble Cedex (France); Marcus, J.; Plaindoux, P. [Institut Neel-MCMF-CNRS-UJF 25, Rue des Martyrs, F 38042 Grenoble Cedex (France)

    2010-09-15

    Investigation of relative AC magnetic susceptibility interests for many magnetic transition studies such as superconductor transition. A technique based on mutual or self inductive measure provides a fast and relatively easy (no contact) way to determinate the temperature of any transition affecting the magnetic susceptibility. The half Wheatstone inductive/resistive bridge is used instead of the usual RLC quarter bridge in order to balance the bore inductance of the coil. A comparison between quarter and half bridge measurements illustrates the accuracy of our device.

  10. 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.

  11. 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.

  12. 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.

  13. Magnetic susceptibility mapping of soil pollution

    International Nuclear Information System (INIS)

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

    2006-01-01

    Fast and cost-effective detection of industrial pollution can significantly promote its ecological, economic and social assesment. A magnetometric method, used for qualitative determination of anthropogenic contamination, meets these requirements but needs further development in more quantitative terms.lt could be used successfully in numerous cases when heavy metals coexists with strongly magnetic iron oxide particles in the source dust. We presented a magnetic study which examines the utility of magnetometric techniques for rapid, qualitative detection of metallic pollutants in soils. In the present paper we tested the use of rock-magnetic method designed to access the degree of pollution of soil taken from Novaky situated in the south-western of Slovakia. The aim was to identify magnetic particles and to link magnetic pollution, to trace distribution and concentration of contaminants in soil. About 40 years the rainwater overflow the dump and flooded out the ash waste from the brown coal power plant in Novaky. Soil samples have been taken from 3 horizons (20, 40 and 60 cm) and measured by KLY-kappabridge in the Slovak Academy of Sciences, in Geophysical Institute in Bratislava. Our results clearly demonstrate that magnetic anomalies can be explained by human activity. (authors)

  14. Ac magnetic susceptibility study of in vivo nanoparticle biodistribution

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-06-29

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

  15. 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.

  16. Magnetic susceptibility of multiferroics and chemical ordering

    Czech Academy of Sciences Publication Activity Database

    Maryško, Miroslav; Laguta, Valentyn; Raevski, I. P.; Kuzian, R. O.; Olekhnovich, N.M.; Pushkarev, A.V.; Radyush, Yu.V.; Raevskaya, S. I.; Titov, V.V.; Kubrin, S.P.

    2017-01-01

    Roč. 7, č. 5 (2017), s. 1-6, č. článku 056409. ISSN 2158-3226 R&D Projects: GA ČR GA13-11473S Institutional support: RVO:68378271 Keywords : multiferroic * spin glass * antiferromagnetic * ferroelectrics Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.568, year: 2016

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

    International Nuclear Information System (INIS)

    Sierra-Bermúdez, Sergio; Maldonado-Camargo, Lorena P.; Orange, François; Guinel, Maxime J.-F.; Rinaldi, Carlos

    2015-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-15

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

  19. Multifractal model of magnetic susceptibility distributions in some igneous rocks

    Directory of Open Access Journals (Sweden)

    M. E. Gettings

    2012-11-01

    Full Text Available Measurements of in-situ magnetic susceptibility were compiled from mainly Precambrian crystalline basement rocks beneath the Colorado Plateau and ranges in Arizona, Colorado, and New Mexico. The susceptibility meter used measures about 30 cm3 of rock and measures variations in the modal distribution of magnetic minerals that form a minor component volumetrically in these coarsely crystalline granitic to granodioritic rocks. Recent measurements include 50–150 measurements on each outcrop, and show that the distribution of magnetic susceptibilities is highly variable, multimodal and strongly non-Gaussian. Although the distribution of magnetic susceptibility is well known to be multifractal, the small number of data points at an outcrop precludes calculation of the multifractal spectrum by conventional methods. Instead, a brute force approach was adopted using multiplicative cascade models to fit the outcrop scale variability of magnetic minerals. Model segment proportion and length parameters resulted in 26 676 models to span parameter space. Distributions at each outcrop were normalized to unity magnetic susceptibility and added to compare all data for a rock body accounting for variations in petrology and alteration. Once the best-fitting model was found, the equation relating the segment proportion and length parameters was solved numerically to yield the multifractal spectrum estimate. For the best fits, the relative density (the proportion divided by the segment length of one segment tends to be dominant and the other two densities are smaller and nearly equal. No other consistent relationships between the best fit parameters were identified. The multifractal spectrum estimates appear to distinguish between metamorphic gneiss sites and sites on plutons, even if the plutons have been metamorphosed. In particular, rocks that have undergone multiple tectonic events tend to have a larger range of scaling exponents.

  20. 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 ...

  1. 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 ...

  2. 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

  3. 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…

  4. 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)

  5. Determining magnetic susceptibilities of everyday materials using an electronic balance

    Science.gov (United States)

    Laumann, Daniel; Heusler, Stefan

    2017-05-01

    The magnetic properties of an object and its interaction with an external magnetic field can be described through the magnetic (volume) susceptibility χV, which divides nearly all kinds of matter into diamagnetic, paramagnetic, and ferromagnetic substances. Quantitative measurements of χV are usually technically sophisticated or require the investigation of substances with high values of χV to reveal meaningful results. Here, we show that both diamagnetic and paramagnetic effects in everyday materials can be measured using only an electronic balance and a neodymium magnet, both of which are within the reach of typical introductory college and high school physics classrooms. The experimental results match related literature values remarkably well.

  6. 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

  7. 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

  8. 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

  9. Nonlinear dynamic susceptibilities of interacting and noninteracting magnetic nanoparticles

    CERN Document Server

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

    2000-01-01

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

  10. Mapping soil magnetic susceptibility and mineralogy in Ukraine

    Science.gov (United States)

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

    2017-04-01

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

  11. 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.

  12. 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

  13. 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

  14. 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.

  15. Magnetic susceptibility of Mn(III) complexes of hydroxamate siderophores.

    Science.gov (United States)

    Springer, Stephen D; Butler, Alison

    2015-07-01

    The hydroxamate siderophores putrebactin, desferrioxamine B, and desferrioxamine E bind Mn(II) and promote the air oxidation of Mn(II) to Mn(III) at pH>7.1. The magnetic susceptibility of the manganese complexes were determined by the Evans method and the stoichiometry was probed with electrospray ionization mass spectrometry (ESIMS). The room temperature magnetic moments (μeff) for the manganese complexes of desferrioxamines B and E were 4.85 BM and 4.84 BM, respectively, consistent with a high spin, d(4), Mn(III) electronic configuration. The manganese complex of putrebactin had a magnetic moment of 4.98 BM, consistent with incomplete oxidation of Mn(II), as confirmed by X band EPR spectroscopy. Mass spectra of the Mn(III) desferrioxamine B and E complexes showed complexes at m/z 613.26 and 653.26, respectively, consistent with 1:1 complexation. Mass spectral peaks for manganese putrebactin at m/z 797.31 and 1221.41 corresponds to 1:2 and 2:3 Mn:putrebactin complexation. This study directly confirms the Mn(III) oxidation state in hydroxamate siderophore complexes. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-05-07

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

  18. 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

  19. [Studying cerebral perfusion using magnetic susceptibility techniques: technique and applications].

    Science.gov (United States)

    Guzmán-de-Villoria, J A; Fernández-García, P; Mateos-Pérez, J M; Desco, M

    2012-01-01

    Perfusion MRI makes it possible to evaluate the cerebral microvasculature through changes in signal due to a tracer passing through blood vessels. The most commonly used technique is based on the magnetic susceptibility of gadolinium in T2*-weighted sequences, and the most commonly evaluated parameters are cerebral blood volume, cerebral blood flow, and mean transit time. Diverse technical aspects, like the sequence used, and the dose and speed of contrast material injection, must be taken into account in perfusion MRI studies. It is also essential to consider possible sources of error like contrast material leaks due to changes in the permeability of the blood-brain barrier. The most widely used clinical applications of perfusion MRI include the determination of the degree of aggressiveness of gliomas, the differentiation of some histological types of tumors or pseudotumors, and the evaluation of the penumbral area in acute ischemia. Copyright © 2011 SERAM. Published by Elsevier Espana. All rights reserved.

  20. 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

  1. 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

  2. Magnetic susceptibility mapping of the human thorax using a SQUID biomagnetometer.

    Science.gov (United States)

    Davies, S C; Ni, C; Fardy, J; Rassi, D

    1994-01-01

    Biomagnetism is essentially the study of the weak magnetic fields generated by biological organisms, in particular the human body. The human thorax is composed of a variety of tissues and organs of slightly different magnetic susceptibility. In an applied magnetic field (of the order of milliTeslas) these small differences in susceptibility lead to measurable field variations (of the order of nanoTeslas) at the body surface which may be of diagnostic value. Physiological processes such as cardiac activity, cardiac output, blood flow and respiratory related lung volume changes also contribute to the observed signal. In this study susceptibility 'maps' were obtained by measuring the magnetic field at several hundred points over the thorax. Results indicate that magnetic susceptibility mapping produces low-resolution images of internal body structures from which is should be possible to detect pathologies that cause alterations in tissue susceptibility.

  3. 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

  4. 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.

  5. Utility of magnetic susceptibility values for the petrographic analysis of weathering crust basement samples

    Directory of Open Access Journals (Sweden)

    Alfredo Hernández-Ramsay

    2018-01-01

    Full Text Available This article exposes the resolving power of the magnetic susceptibility measurements in basement minerals samples of the lateritic weathering profile as an element of complementary analysis in the petrographic characterization of the rocks, and useful in the mapping of the magnetic heterogeneities of the basement. The comparison of the magnetic susceptibility data with the petrographic data of different samples revealed that even in samples that correspond to homogeneous lithotypes, great heterogeneities and differences can be manifested from the physical-mineralogical point of view. In general, a high concordance was observed between the intensity of the weathering processes in the rock samples, and the values of the magnetic susceptibility of such samples. The results support the possibility of extrapolating the composition information to samples with magnetic susceptibility measurements and without petrographic studies.

  6. 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

  7. 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

  8. Local magnetic susceptibility of the muon in the S=1/2V{sub 15} molecular nano-magnet

    Energy Technology Data Exchange (ETDEWEB)

    Salman, Z., E-mail: z.salman1@physics.ox.ac.u [Department of Physics, Clarendon Laboratory, Oxford University, Parks Road, Oxford OX1 3PU (United Kingdom); ISIS Facility, Rutherford Appleton Laboratory, Chilton, Oxfordshire OX11 0QX (United Kingdom); Kiefl, R.F. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Canadian Institute for Advanced Research (Canada); Chow, K.H. [Department of Physics, University of Alberta, Edmonton, AB, T6G 2G7 (Canada); MacFarlane, W.A. [Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Keeler, T.A. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Parolin, T.J. [Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Wang, D. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada)

    2009-04-15

    We report muon spin rotation measurements of the local magnetic susceptibility around a positive muon in the V{sub 15} spin 1/2 molecular nano-magnet. We find that the measured temperature dependence of the local susceptibility agrees with bulk. No temperature dependence is observed below 200 mK, indicating that at these temperatures the V{sub 15} molecular spin resides in its S=1/2 ground state.

  9. 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

  10. 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

    ...) method in UXO discrimination problems. We have demonstrated that the static magnetic susceptibility can be effectively modeled using a correlated random process, and that Wiener optimal filter can be used as a preprocessing tool to remove...

  11. 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

  12. 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 into ...

  13. 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

  14. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-01-01

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

  16. 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.

  17. Enhancement of MS2D Bartington point measurement of soil magnetic susceptibility

    Science.gov (United States)

    Fabijańczyk, Piotr; Zawadzki, Jarosław

    2015-04-01

    Field magnetometry is fast method used to assess the potential soil pollution. The most popular device used to measure the soil magnetic susceptibility on the soil surface is a MS2D Bartington. Single reading using MS2D device of soil magnetic susceptibility is low time-consuming but often characterized by considerable errors related to the instrument or environmental and lithogenic factors. Typically, in order to calculate the reliable average value of soil magnetic susceptibility, a series of MS2D readings is performed in the sample point. As it was analyzed previously, such methodology makes it possible to significantly reduce the nugget effect of the variograms of soil magnetic susceptibility that is related to the micro-scale variance and measurement errors. The goal of this study was to optimize the process of taking a series of MS2D readings, whose average value constitutes a single measurement, in order to take into account micro-scale variations of soil magnetic susceptibility in proper determination of this parameter. This was done using statistical and geostatistical analyses. The analyses were performed using field MS2D measurements that were carried out in the study area located in the direct vicinity of the Katowice agglomeration. At 150 sample points 10 MS2D readings of soil magnetic susceptibility were taken. Using this data set, series of experimental variograms were calculated and modeled. Firstly, using single random MS2D reading for each sample point, and next using the data set increased by adding one more MS2D reading, until their number reached 10. The parameters of variogram: nugget effect, sill and range of correlation were used to determine the most suitable number of MS2D readings at sample point. The distributions of soil magnetic susceptibility at sample point were also analyzed in order to determine adequate number of readings enabling to calculate reliable average soil magnetic susceptibility. The research leading to these results has

  18. 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

  19. 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

  20. High magnetic field susceptibility and neutron scattering measurements for ZnFe2O4 single crystal

    International Nuclear Information System (INIS)

    Kamazawa, Kazuya; Nakajima, Kenji; Kohn, Key; Tsunoda, Yorihiko

    2004-01-01

    We studied field dependences of magnetic susceptibility and neutron scattering measurements for frustrated normal spinel ZnFe 2 O 4 . Although a peak which is similar to the antiferromagnetic transition is observed at 13 K in the magnetic susceptibility, there is no magnetic long-range order in our neutron scattering measurements. When we measure the magnetic susceptibility under the high magnetic field, the peak position moves toward the high temperature. In the neutron scattering measurements, magnetic diffuse scattering around the nuclear Bragg peaks disappear under the magnetic field of 3 T

  1. 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.

  2. 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

  3. ESR and magnetic susceptibilities in the '2223' superconductors

    International Nuclear Information System (INIS)

    Geru, I.I.; Pop, A.V.; Konopko, L.A.; Ilonca, Gh.; Pop, V.; Cosma, I.

    1995-01-01

    Electron paramagnetic resonance (EPR) of the (Bi Pb)-(Sr Ba)-Ca-Cu-O high T c superconductor was performed. The a.c. susceptibility shows two superconducting transitions at 109 K and 88 K respectively. An unusual behaviour is observed at 240 K in the EPR linewidth and in the Lande factor (the g value). (author) 3 figs., 12 refs

  4. 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.

  5. In situ identification, pairing, and classification of meteorites from Antarctica through magnetic susceptibility measurements

    Science.gov (United States)

    Folco, Luigi; Rochette, Pierre; Gattacceca, JéRôMe; Perchiazzi, Natale

    2006-03-01

    We report on the effectiveness of using magnetic measurements in the search for meteorites on the Antarctic ice sheet, which is thus far the Earth's most productive terrain. Magnetic susceptibility measurements carried out with a pocket meter (SM30) during the 2003/04 PNRA meteorite collection expedition to northern Victoria Land (Antarctica) proved to be a rapid, sensitive, non-destructive means for the in situ identification, pairing, and classification of meteorites. In blue ice fields characterized by the presence of moraines and glacial drifts (e.g., Miller Butte, Roberts Butte, and Frontier Mountain), magnetic susceptibility measurements allowed discrimination of meteorites from abundant terrestrial stones that look like meteorites thanks to the relatively high magnetic susceptibility of the former with respect to terrestrial rocks. Comparative measurements helped identify 16 paired fragments found at Johannessen Nunataks, thereby reducing unnecessary duplication of laboratory analyses and statistical bias. Following classifications schemes developed by us in this and previous works, magnetic susceptibility measurements also helped classify stony meteorites directly in the field, thereby providing a means for selecting samples with higher research priority. A magnetic gradiometer capable of detecting perturbations in the Earth's magnetic field induced by the presence of meteorites was an efficient tool for locating meteorites buried in snow along the downwind margin of the Frontier Mountain blue ice field. Based on these results, we believe that magnetic sensors should constitute an additional payload for robotic search for meteorites on the Antarctic ice sheet and, by extension, on the surface of Mars where meteorite accumulations are predicted by theoretical works. Lastly, magnetic susceptibility data was successfully used to crosscheck the later petrographic classification of the 123 recovered meteorites, allowing the detection of misclassified or peculiar

  6. Magnetic Susceptibility depending on the Thermal Degradation of HK-40 Steel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeong Min; Park, Jong Seo; Nahm, Seung Hoon [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of); Son, De Rac [Hannam University, Daejeon (Korea, Republic of); Kim, Dong Gyun [Kyungpook National University, Daegu (Korea, Republic of); Han, Sang In; Choi, Song Chun [Korea Gas Safety Corporation, Siheung (Korea, Republic of); Ryu, Dae Hyun [Hansei University, Gunpo (Korea, Republic of)

    2004-02-15

    Since the used materials of furnace heater tube with different kinds of thermal degradation were not commonly available, the HK-40 steel specimens were heat-treated isothermally at elevated temperature to simulate the microstructure at the service temperature. HK-40 steel specimens with five different aging time were prepared by isothermal heat treatment at 1050 .deg. C . The characteristics of the magnetic susceptibility have been investigated for the degradation evaluation of HK-40 steel. The magnetic susceptibility at room temperature increases as the extent of degradation of the materials increases. The variation of magnetic susceptibility was compared with the variation of tensile properties and Vickers hardness. To investigate the effect of the microsturctural change on the characteristics of tensile properties, hardness and magnetic susceptibility, the microstructures were examined by a scanning electron microscope(SEM) and the chemical compositions were analyzed by a energy spectrometer of SEM. As a result, the magnetic susceptibility method can be suggested as one of the nondestructive evaluation methods for the degradation of the HK-40 steel

  7. 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

  8. Simultaneous effects of electron-electron interactions, Rashba spin-orbit interaction and magnetic field on susceptibility of quantum dots

    Science.gov (United States)

    Khordad, R.

    2018-03-01

    In this work, we have theoretically studied susceptibility of an InAs quantum dot in the presence of Rashba spin-orbit interaction (SOI), electron-electron (e--e-) interaction, and magnetic field. We have used two potential models, shifted parabolic and inverse lateral shifted parabolic potentials. We have first solved the Schrodinger equation to obtain energy levels and then obtain the susceptibility using canonical ensemble. It is found that the susceptibility at low magnetic field is negative and then it becomes positive with increasing the magnetic field. This transition occurs at a particular magnetic field. The transition diamagnetism to paramagnetism occurs at lower magnetic field when the temperature increases. The susceptibility reduces with increasing temperature without considering the Rashba SOI. With considering e--e- interaction, the peak position of susceptibility shifts toward lower magnetic fields. Also, the temperature has an effect on width and height of susceptibility.

  9. 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.

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

    Science.gov (United States)

    Ulfah, Melianna; Wijatmoko, Bambang; Fitriani, Dini

    2017-04-01

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

  11. 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

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

    Science.gov (United States)

    Starcuková, Jana; Starcuk, Zenon; Hubálková, Hana; Linetskiy, Igor

    2008-06-01

    The aim of this study was to test the hypothesis that dental materials vary significantly in MR-relevant material parameters-magnetic susceptibility and electrical conductivity, and that knowledge of these parameters may be used to estimate the quality of MR imaging in the presence of devices made of such materials. Magnetic susceptibility, electrical conductivity and artifacts were evaluated for 45 standardized cylindrical samples of dental alloys and amalgams. Magnetic susceptibility was determined by fitting the phase of gradient-echo MR images to numerically modeled data. Electrical conductivity was determined by standard electrotechnical measurements. Artifact sizes were measured in spin-echo (SE) and gradient-echo (GE) images at 1.5T according to the standards of the American Society for Testing and Materials. It has been confirmed that dental materials differ considerably in their magnetic susceptibility, electrical conductivity and artifacts. For typical dental devices, magnetic susceptibility differences were found of little clinical importance for diagnostic SE/GE imaging of the neck and brain, but significant for orofacial imaging. Short-TE GE imaging has been found possible even in very close distances from dental devices made of amalgams, precious alloys and titanium alloys. Nickel-chromium and cobalt-chromium artifacts were found still acceptable, but large restorations of aluminum bronzes may preclude imaging of the orofacial region. The influence of electrical conductivity on the artifact size was found negligible. MR imaging is possible even close to dental devices if they are made of dental materials with low magnetic susceptibility. Not all materials in current use meet this requirement.

  13. 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.)

  14. Modified mean-field theory of the magnetic properties of concentrated, high-susceptibility, polydisperse ferrofluids.

    Science.gov (United States)

    Solovyova, Anna Yu; Elfimova, Ekaterina A; Ivanov, Alexey O; Camp, Philip J

    2017-11-01

    The effects of particle-size polydispersity on the magnetostatic properties of concentrated ferrofluids are studied using theory and computer simulation. The second-order modified mean-field (MMF2) theory of Ivanov and Kuznetsova [Phys. Rev. E 64, 041405 (2001)1063-651X10.1103/PhysRevE.64.041405] has been extended by calculating additional terms of higher order in the dipolar coupling constant in the expansions of the initial magnetic susceptibility and the magnetization curve. The theoretical predictions have been tested rigorously against results from Monte Carlo simulations of model monodisperse, bidisperse, and highly polydisperse ferrofluids. Comparisons have been made between systems with the same Langevin susceptibility and the same saturation magnetization. In all cases, the new theoretical magnetization curve shows better agreement with simulation data than does the MMF2 theory. As for the initial susceptibility, MMF2 theory is most accurate for the monodisperse model, while the new theory works best for polydisperse systems with a significant proportion of large particles. These results are important for the analysis and characterization of recently synthesized polydisperse ferrofluids with record-breaking values of the initial magnetic susceptibility.

  15. Magnetic susceptibility and heavy metals contamination in soils of Southern Poland

    Science.gov (United States)

    Strzyszcz, Z.; Magiera, T.

    The anthropogenic character of the increase in magnetic susceptibility of Silesian soils is doubtless. The dependence between the magnetic susceptibility of industrial dust and the concentration of heavy metals was investigated. Correlation coefficients between those two parameters range for metallurgic dust from 0.911 to 0.998 for Ni and Zn, for fly ashes from 0.710 to 0.820, for Pb and Zn, for cement dust from 0.261 to 0.519 for Ni and Pb, respectively. The anthropogenic character of this dependence is also confirmed by the values of the correlation coefficients between magnetic susceptibility and dust emission, fly ash, metallurgic dust, cement dust, are 0.903, 0.867, 0.918 and 0.365, respectively. For immission the correlation coefficients are as follow: 0.817, 0.656, 0.440 for dustfall, suspended dust and iron fall, respectively. In magnetic particles selected from fly ashes high concentrations of Pb, Zn, Ni and Cu were found. Regarding dependence of magnetic susceptibility on concentration of heavy metals in soils Upper Silesian Industrial Region the correltion coefficients were: between 0.616 - 0.986 for Zn, 0.724 - 0.979 for Pb, and 0.175 - 0.581 for Cd. These values were lower for 90 soil profiles collected from an area of 22 000 km 2 (Katowice Forest State Directorate) resulting from varying conditions of emission and immission of industrial pollutants.

  16. Possibility of third-order magnetic susceptibility investigations in magnetic materials

    International Nuclear Information System (INIS)

    Bazhan, A.N.

    2004-01-01

    Three-coordinate vector magnetometer for investigations of the magnetic field dependencies of the three separate magnetic moment components, along and perpendicular to the applied magnetic field, is described. Additionally to investigations of the sample magnetic moments orientations with respect to sample axis in magnetically ordered materials, possibilities in investigations of non-linear magnetic field dependencies of sample magnetic moments components of some paramagnetic materials are discussed

  17. Discrimination of lithogenic and anthropogenic influences on topsoil magnetic susceptibility in Central Europe

    Czech Academy of Sciences Publication Activity Database

    Magiera, T.; Strzyszcz, Z.; Kapička, Aleš; Petrovský, Eduard

    2006-01-01

    Roč. 130, 3-4 (2006), s. 299-311 ISSN 0016-7061 R&D Projects: GA AV ČR KSK3046108; GA AV ČR IBS3012354 Grant - others:EC(XE) EVK2-CT-1999-00019 Institutional research plan: CEZ:AV0Z3012916 Keywords : magnetic susceptibility * soil profiles * anthropogenic pollution Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 2.124, year: 2006

  18. 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

  19. Sixty years of anisotropy of magnetic susceptibility in deformed sedimentary rocks

    OpenAIRE

    Parés, Josep M.

    2015-01-01

    The use of the Anisotropy of Magnetic Susceptibility (AMS) has become a rather common practice in Earth Sciences since the pioneer note by Graham (1954). The versatility of the technique, and the rapidness in obtaining and processing AMS data largely improved in the past thirty years, and has generated a wealth of literature, notably on mudrock fabrics. The assessment of the current trends in magnetic fabric studies reveals that AMS has one of its largest potential in sedimentary rocks from s...

  20. Influence of iron valency on the magnetic susceptibility of a microbially produced iron sulphide

    Energy Technology Data Exchange (ETDEWEB)

    Marius, M S; James, P A B; Bahaj, A S; Smallman, D J [University of Southampton, School of Civil Engineering and the Environment, Southampton, SO17 1BJ (United Kingdom)

    2005-01-01

    Microbial iron sulphide is well known as an adsorbent for the treatment of metallic ion polluted wastewater. Under certain culture conditions a highly magnetic iron sulphide can be produced which would enable a low cost biomagnetic separation process to be developed. This paper illustrates that by raising the ferrous content of a ferrous - ferric sulphate rich medium the magnetic susceptibility of the iron sulphide produced is increased.

  1. Influence of iron valency on the magnetic susceptibility of a microbially produced iron sulphide.

    Science.gov (United States)

    Marius, M. S.; James, P. A. B.; Bahaj, A. S.; Smallman, D. J.

    2005-01-01

    Microbial iron sulphide is well known as an adsorbent for the treatment of metallic ion polluted wastewater. Under certain culture conditions a highly magnetic iron sulphide can be produced which would enable a low cost biomagnetic separation process to be developed. This paper illustrates that by raising the ferrous content of a ferrous - ferric sulphate rich medium the magnetic susceptibility of the iron sulphide produced is increased.

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

    Science.gov (United States)

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

    2016-01-01

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

  3. The detection of common cycles in magnetic susceptibility observed in distant magnetostratigraphic sections

    Czech Academy of Sciences Publication Activity Database

    Man, Otakar; Pruner, Petr; Schnabl, Petr

    2012-01-01

    Roč. 56, č. 3 (2012), s. 735-750 ISSN 0039-3169 R&D Projects: GA ČR GA205/07/1365 Institutional research plan: CEZ:AV0Z30130516 Keywords : time-series analysis * spectral analysis * magnetostratigraphy * magnetic susceptibility * Milankovitch cycles Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.975, year: 2012

  4. Inhomogeneity of asteroid 2008 TC3 (Almahata Sitta meteorites) revealed through magnetic susceptibility measurements

    Czech Academy of Sciences Publication Activity Database

    Kohout, Tomáš; Jenniskens, P.; Shaddad, M.H.; Haloda, J.

    2010-01-01

    Roč. 45, 10/11 (2010), s. 1778-1788 ISSN 1086-9379 R&D Projects: GA AV ČR KJB300130903 Institutional research plan: CEZ:AV0Z30130516 Keywords : ureilite * magnetic susceptibility * Almahata Sitta * 2008 TC3 Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.624, year: 2010

  5. Magnetic susceptibility as a tool for characterization of an asteroid regolith and sample return

    Czech Academy of Sciences Publication Activity Database

    Kohout, Tomáš; Britt, D.

    2011-01-01

    Roč. 46, Supplement (2011), A128-A128 ISSN 1086-9379. [Annual Meeting of the Meteoritical Society /74./. 08.08.2011-12.08.2011, London] Institutional research plan: CEZ:AV0Z30130516 Keywords : magnetic susceptibility * meteorite * asteroid Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  6. 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.

  7. 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

  8. Magnetic susceptibility of complex compounds of rhenium with 1.2.4-triazole

    International Nuclear Information System (INIS)

    Avetikyan, G.B.; Amindzhanov, A.A.; Gagieva, S.Ch.; Kotegov, K.V.

    1991-01-01

    Present article is devoted to magnetic susceptibility of complex compounds of rhenium with 1.2.4-triazole. The thermal transformations of chloride-1.2.4-triazole rhenium complexes were studied by means of static magneto chemistry and thermal differential analysis methods.

  9. 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.

  10. Alternating current magnetic susceptibility of a molecular magnet submonolayer directly patterned onto a micro superconducting quantum interference device

    International Nuclear Information System (INIS)

    Martínez-Pérez, M. J.; Luis, F.; Bellido, E.; Ruiz-Molina, D.; Miguel, R. de; Sesé, J.; Lostao, A.

    2011-01-01

    We report the controlled integration, via dip pen nanolithography, of monolayer dots of ferritin-based CoO nanoparticles (12 μ B ) into the most sensitive areas of a microSQUID sensor. The nearly optimum flux coupling between these nanomagnets and the microSQUID improves the achievable sensitivity by a factor 10 2 , enabling us to measure the linear susceptibility of the molecular array down to very low temperatures (13 mK). This method opens the possibility of applying ac susceptibility experiments to characterize two-dimensional arrays of single molecule magnets within a wide range of temperatures and frequencies.

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

    Science.gov (United States)

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

    2016-04-01

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

  12. 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 data.

  13. Out-of-phase magnetic susceptibility of rocks and soils: a rapid tool for magnetic granulometry

    Czech Academy of Sciences Publication Activity Database

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

    2013-01-01

    Roč. 194, č. 1 (2013), s. 170-181 ISSN 0956-540X R&D Projects: GA ČR GAP210/10/2351 Institutional support: RVO:67985831 Keywords : environmental magnetism * magnetic mineralogy and petrology * rock and mineral magnetism Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 2.724, year: 2013

  14. Magnetic susceptibility as an indicator of heavy metal contamination in compost.

    Science.gov (United States)

    Paradelo, Remigio; Moldes, Ana Belén; Barral, María Teresa

    2009-02-01

    One of the main restrictions to the agronomic use of compost is the excess of heavy metals, which are often present due to inadequate separation of biodegradable fractions from non-degradable or inert materials. Magnetic susceptibility (MS) measurements are a simple technique that has been reported as a useful tool for assessing anthropogenic pollution, especially heavy metal pollution on soil and sediment samples. The close relationship of MS with heavy metal contamination has been proved by combined analyses of chemical and magnetic data. In this study, the MS and total heavy metal concentrations of eight composts from different origins were determined; all composts were passed under a magnet to remove the magnetic material, and total heavy metals were determined again. In our work, high correlations were found between magnetic susceptibility and total Cd, Zn, Pb, Cr and Ni, thus confirming the applicability of MS measurement as a proxy for heavy metal contamination in compost quality assessments. The application of a magnet over the composts reduced the MS as well as the heavy metal content, the reduction of Fe and MS being the most significantly correlated. Thus, the inclusion of an additional magnetic separation step in the post-process compost finishing could be envisaged.

  15. 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.

  16. 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.

  17. 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).

  18. Monitoring colloidal stability of polymer-coated magnetic nanoparticles using AC susceptibility measurements.

    Science.gov (United States)

    Herrera, Adriana P; Barrera, Carola; Zayas, Yashira; Rinaldi, Carlos

    2010-02-15

    The application of the response of magnetic nanoparticles to oscillating magnetic fields to probe transitions in colloidal state and structure of polymer-coated nanoparticles is demonstrated. Cobalt ferrite nanoparticles with narrow size distribution were prepared and shown to respond to oscillating magnetic fields through a Brownian relaxation mechanism, which is dependent on the mechanical coupling between the particle dipoles and the surrounding matrix. These nanoparticles were coated with covalently-attached poly(N-isopropylacrylamide) (pNIPAM) or poly(N-isopropylmethacrylamide) (pNIPMAM) through free radical polymerization. The temperature induced transitions of colloidal suspensions of these nanoparticles were studied through a combination of differential scanning calorimetry (DSC), dynamic light scattering (DLS), and AC susceptibility measurements. In the pNIPAM coated nanoparticles excellent agreement was found for a transition temperature of approximately 30 degrees C by all three methods, although the AC susceptibility measurements indicated aggregation which was not evident from the DLS results. Small-angle neutron scattering (SANS) results obtained for pNIPAM coated nanoparticles confirmed that aggregation indeed occurs above the lower critical transition temperature of pNIPAM. For the pNIPMAM coated nanoparticles DLS and AC susceptibility measurements indicated aggregation at a temperature of approximately 33-35 degrees C, much lower than the transition temperature peak at 40 degrees C observed by DSC. However, the transition observed by DSC is very broad, hence it is possible that aggregation begins to occur at temperatures lower than the peak, as indicated by the AC susceptibility and DLS results. These experiments and observations demonstrate the possibility of using AC susceptibility measurements to probe transitions in colloidal suspensions induced by external stimuli. Because magnetic measurements do not require optical transparency, these

  19. Temperature dependence of the magnetic volume susceptibility of human breast fat tissue: an NMR study.

    Science.gov (United States)

    Sprinkhuizen, Sara M; Bakker, Chris J G; Ippel, Johannes H; Boelens, Rolf; Viergever, Max A; Bartels, Lambertus W

    2012-02-01

    Proton resonance frequency shift (PRFS)-based MR thermometry (MRT) is hampered by heat-induced susceptibility changes when applied in tissues containing fat, e.g., the human breast. In order to assess the impact of fat susceptibility changes on PRFS-based MRT during thermal therapy in the human breast, reliable knowledge of the temperature dependence of the magnetic volume susceptibility of fat, dχ(fat)/dT, is a prerequisite. In this work we have measured dχ(fat)/dT of human breast fat tissue, using a double-reference method to ensure invariance to temperature-induced changes in the proton electron screening constant. Ex vivo measurements were taken on a 14.1 T five mm narrow bore NMR spectrometer. Breast fat tissue samples were collected from six subjects, directly postmortem. The susceptibility was measured over a temperature range from 24°C to 65°C. A linear behavior of the susceptibility over temperature was observed for all samples. The resulting dχ(fat)/dT of human breast fat ranged between 0.0039 and 0.0076 ppm/°C. It is concluded that the impact of heat-induced susceptibility changes of fat during thermal therapy in the breast may not be neglected.

  20. Anisotropy of the Magnetic Susceptibility of the Alnö alkaline and carbonatite igneous complex

    Science.gov (United States)

    Andersson, M.; Almqvist, B.; Malehmir, A.; Troll, V. R.; Snowball, I.; Lougheed, B.

    2013-12-01

    The Alnö igneous complex in central Sweden is one of the largest (radius ~2.5 km) of the few well-known alkaline and carbonatite ring-intrusions in the world. The lithologies span from alkaline silicate rocks (nepheline syenite, ijolite, and pyroxenite) to a range of carbonatite dykes (e.g. sövite) with variable composition. The depth extent, dip, and dip direction of the alkaline and carbonatite rocks have been inferred from surface geological mapping, and a dome-shaped magma chamber with the roof at ~2 km below the palaeosurface was inferred to have supplied steeply dipping radial dykes and (shallowly dipping) cone sheets. Recent high-resolution reflection seismic profiles and gravity and ground magnetic measurements suggest, in turn, a saucer-shaped magma chamber at ~3 km depth below present day land surface. To provide further insight into the internal flow mechanics of these dykes and into their emplacement mechanisms, we have measured the anisotropy of magnetic susceptibility (AMS). About 250 samples from 119 oriented cores were collected with a handheld drilling machine from 26 localities within the Alnö complex. Prior to preparation of discrete samples for AMS, the cores were measured for their density and for ultrasonic P- and S-wave velocities. Most of the sampling locations lie on a transect through the intrusion. Three locations have been sampled in detail, to determine the variation of AMS within individual carbonatite dykes. The AMS of samples were measured in low-field, using a KLY-2 Kappabridge. Bulk magnetic susceptibility ranges from 3.01e-5 to 2.50e-1 SI, and correlates with lithology. The sövites have the widest range of susceptibility (average 4.32e-2, with a range from 3.01e-5 to 2.50e-1 SI), whereas fenites have the lowest average susceptibility (average 2.06e-3, with a range from 9.86e-5 to 1.47e-2 SI); nepheline-syenite, ijolite and pyroxenite have susceptibilities between these two end member lithologies. Sövite consists mainly of

  1. Magnetic susceptibility of the Kagome antiferromagnet ZnCu3(OH)6Cl2.

    Science.gov (United States)

    Rigol, Marcos; Singh, Rajiv R P

    2007-05-18

    We analyze the experimental data for the magnetic susceptibility of the material ZnCu3(OH)6Cl2 in terms of the Kagome Lattice Heisenberg model (KLHM), discussing possible role of impurity spins, dilution, exchange anisotropy, and both out-of-plane and in-plane Dzyloshinski-Moriya (DM) anisotropies, with explicit theoretical calculations using the numerical linked cluster method and exact diagonalization. The high-temperature experimental data are well described by the pure Heisenberg model with J=170 K. We show that the sudden upturn in the susceptibility around T=75 K is due to DM interactions. We also observe that at intermediate temperatures, below T=J, our calculated susceptibility for KLHM fits well with a power law T(-0.25).

  2. Impact of Long-Term Irrigation with Treated Sewage on Soil Magnetic Susceptibility and Organic Matter Content in North China.

    Science.gov (United States)

    Yang, P G; Yang, M; Mao, R Z; Byrne, J M

    2015-07-01

    This study assessed the effect on magnetic susceptibility and organic matter content of arable soil by irrigation with either treated sewage or groundwater. Results indicated that organic matter and magnetic susceptibility values in the soil irrigated with sewage were increased by 7.1 % and 13.5 %, respectively, compared to agricultural soil that irrigated with groundwater. Both the sewage and groundwater irrigated soils contained a significant fraction of ultrafine superpara magnetic grains, as indicated by high frequency dependent susceptibility (χfd > 6 %). The enhancement of soil magnetic properties was determined to be caused by anthropogenic sewage irrigation and agrochemical use by investigation of vertical soil profiles. Magnetic susceptibility parameters were shown to be significantly correlated with organic matter content (y = 0.0057x + 1.3439, R(2) = 0.09, p soils.

  3. Investigation of roadside pollution in Aliaga Industrial Zone (Izmir/Turkey) by using magnetic susceptibility

    Science.gov (United States)

    Timur, Emre

    2014-05-01

    Pollution of soils is significantly reducing environmental quality and affecting human health. As a condition for effective protection and remediation actions, the screening and detection of soil and sediment pollution has become increasingly important. The pollutants of most cases are usually heavy metals, organic contaminants and agricultural applications such as chemical fertilizers, pestisides and hormones. The aim of this study is to trace the distribution and concentration of contaminants in soils along roads carrying both appreciably high and low traffic along three roads around Aliaga industrial zone. Magnetic susceptibility (Bartington MS2E) is used for pollution mapping in the field. The distribution of the susceptibility values represents contaminated areas strongly influenced by traffic frequency, roadside topography, vegetation and meteorological conditions. It was determined that approximately 5 m along both sides of Canakkale-Izmir highway, which has a very high traffic density (250 car/min), shows very high susceptibility values in comparison with the rest of the profile. This value reduced to 2.4 m and 0.7 m along two side roads, which are 300 and 1100 m away from the highway. Also these roads were having traffic densities of 47 cars/min and 3 cars/min respectively. The measurements were repeated in summer and winter seasons in order to observe possible climate effects. Also soil samples were collected at 2 stations in both sides of the roads to compare the heavy metal content with the background values. According to geochemical data Fe-oxides are found to be responsible for the high values of magnetic susceptibility. It was determined that magnetic susceptibility is a rapid and cheap method for investigating potentially contaminated areas.

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

    Directory of Open Access Journals (Sweden)

    L. Sagnotti

    1994-06-01

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

  5. 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.

  6. 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.

  7. 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

  8. Magnetic susceptibility, electrical resistivity and elastic constants of antiferromagnetic UN single crystals

    International Nuclear Information System (INIS)

    Du Plessis, P. de V.; Doorn, C.F. van

    1977-01-01

    Susceptibility and electrical resistivity measurements on UN indicate Tsub(N) approximately 53 K. The spin-disorder resistivity is mainly proportional to 1-m 2 sub(n)(msub(n) is the reduced sublattice magnetization). The elastic constant C 44 shows a renormalization proportional to M 2 sub(n), whereas C 11 exhibits an anomalous softening of 10% well below Tsub(N) at 47 K. (Auth.)

  9. 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

  10. 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

    Sediment tracing using a single tracer, low frequency magnetic susceptibility (X lf ), was used to apportion suspended sediment to geologically defined source areas and to interpret sediment source changes during flood events in the degraded catchment of the Vuvu River, a headwater tributary of the Mzimbubu River, South Africa. The method was tested as a simple tool for use by catchment managers concerned with controlling erosion. The geology of the 58 km 2 catchment comprises two distinct formations: basalt in the upper catchment with a characteristically high magnetic susceptibility and shales with a low magnetic susceptibility in the lower catchment. Application of an unmixing model incorporating a Monte Carlo uncertainty analysis showed that X lf provided a means to assign the proportion of each geological province contributing to the river's sediment load. Grab water samples were collected at ten-minute intervals during flood events for subsequent analysis of suspended sediment concentration and the magnetic susceptibility of the filtered sediment. Two floods are presented in detail, the first represents a significant event at the start of the wet season (max. discharge 32 m 3  s -1 ); the second was a smaller flood (max discharge 14 m 3  s -1 ) that occurred a month later. Suspended sediment concentrations during the twelve monitored events showed a characteristic decline over the wet season. The main source of suspended sediment was shown to be from the mudstones in the lower catchment, which contributed 86% of the total measured load. The sediment dynamics during the two floods monitored in detail were quite different from each other. In the first the sediment concentration was high (11 g L -1 ), peaking after the flood peak. The X lf value increased during the event, indicating that contribution to the sediment load from basalt in the upper catchment increased during the recession limb. In the second, smaller flood the sediment peak (6 g L -1

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-15

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

  12. 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.

  13. 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.

  14. Sixty Years of Anisotropy of Magnetic Susceptibility in deformed sedimentary rocks

    Directory of Open Access Journals (Sweden)

    Josep M Pares

    2015-02-01

    Full Text Available The use of the Anisotropy of Magnetic Susceptibility (AMS has become a rather common practice in Earth Sciences since the pioneer note by Graham (1954. The versatility of the technique, and the rapidness in obtaining and processing AMS data largely improved in the past thirty years, and has generated a wealth of literature, notably on mudrock fabrics. The assessment of the current trends in magnetic fabric studies reveals that AMS has one of its largest potential in sedimentary rocks from structural settings where the ductile component of deformation is cryptic or hindered by the brittle component. Abundant evidence provided by AMS data reveal that deformation extents beyond the deformation or cleavage front in contractional settings, including fold-and-thrust belts and active accretionary prisms, configuring magnetic fabrics as a standard method for fabric quantification in deformed sedimentary rocks.

  15. 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

  16. Magnetic susceptibility anisotropy: cylindrical symmetry from macroscopically ordered anisotropic molecules and accuracy of MRI measurements using few orientations.

    Science.gov (United States)

    Wisnieff, Cynthia; Liu, Tian; Spincemaille, Pascal; Wang, Shuai; Zhou, Dong; Wang, Yi

    2013-04-15

    White matter is an essential component of the central nervous system and is of major concern in neurodegenerative diseases such as multiple sclerosis (MS). Recent MRI studies have explored the unique anisotropic magnetic properties of white matter using susceptibility tensor imaging. However, these measurements are inhibited in practice by the large number of different head orientations needed to accurately reconstruct the susceptibility tensor. Adding reasonable constraints reduces the number of model parameters and can help condition the tensor reconstruction from a small number of orientations. The macroscopic magnetic susceptibility is decomposed as a sum of molecular magnetic polarizabilities, demonstrating that macroscopic order in molecular arrangement is essential to the existence of and symmetry in susceptibility anisotropy and cylindrical symmetry is a natural outcome of an ordered molecular arrangement. Noise propagation in the susceptibility tensor reconstruction is analyzed through its condition number, showing that the tensor reconstruction is highly susceptible to the distribution of acquired subject orientations and to the tensor symmetry properties, with a substantial over- or under-estimation of susceptibility anisotropy in fiber directions not favorably oriented with respect to the acquired orientations. It was found that a careful acquisition of three non-coplanar orientations and the use of cylindrical symmetry guided by diffusion tensor imaging allowed reasonable estimation of magnetic susceptibility anisotropy in certain major white matter tracts in the human brain. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Temporal Changes in Magnetic Susceptibility Induced by Microbial Manipulation of Iron Minerals

    Science.gov (United States)

    Enright, A. M.; Price, A.; Rosier, C. L.; Beaver, C. L.; Rossbach, S.; Ntarlagiannis, D.; Slater, L. D.; Lund, A.; Atekwana, E. A.

    2016-12-01

    Sequential iron extractions were used to determine the mineral and oxidation state speciation of iron in a series of cores from an oil spill site in Bemidji, Minnesota. Cores were collected over five years, from a location where a magnetic susceptibility (MS) anomaly was initially observed in 2011. Further field and laboratory MS measurements confirmed the magnetic anomaly, yet revealed a trend to lower MS values over the measured time frame. Conventional interpretation typically dictates that MS peaks are indicative of mixed-valence oxide mineral phases (i.e. magnetite or greigite) here the diminished, but persistent MS anomaly is most closely coupled with high concentrations of the fully-oxidized iron oxides, such as hematite. Microbiological community fingerprinting analysis (PCR-DGGE) of core samples suggest that the anomaly could result from methanogenically-derived magnetite occurring during water table high stand, which was then oxidized as water levels seasonally decreased. The diminished, but persistent presence of magnetic susceptibility anomaly appears to indicate the transformation of magnetite to iron oxides mediated by microbial metabolic processes (i.e. methanogenesis). We hypothesize that the MS response is related to the biological transformations of iron in the groundwater table fluctuation zone, and that the magnitude of the anomaly evolves along with oxidation state of iron in the sediments, and may serve as a record of the microbial manipulation of iron.

  18. 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.

  19. 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

  20. Momentum-dependent susceptibilities and magnetic exchange in bcc iron from supercell dynamical mean-field theory calculations

    Science.gov (United States)

    Belozerov, A. S.; Katanin, A. A.; Anisimov, V. I.

    2017-08-01

    We analyze the momentum and temperature dependences of the magnetic susceptibilities and magnetic exchange interaction in paramagnetic bcc iron by a combination of density functional theory and dynamical mean-field theory (DFT+DMFT). By considering a general derivation of the orbital-resolved effective model for spin degrees of freedom for Hund's metals, we relate momentum-dependent susceptibilities in the paramagnetic phase to the magnetic exchange. We then calculate nonuniform orbital-resolved susceptibilities at high-symmetry wave vectors by constructing appropriate supercells in the DMFT approach. Extracting the irreducible parts of susceptibilities with respect to Hund's exchange interaction, we determine the corresponding orbital-resolved exchange interactions, which are then interpolated to the whole Brillouin zone. Using the spherical model we estimate the temperature dependence of the resulting exchange between local moments.

  1. Low temperature magnetic susceptibility behavior of the Neuschwanstein EL6 meteorite and mineral daubreelite (FeCr2S4)

    Czech Academy of Sciences Publication Activity Database

    Kohout, Tomáš; Kletetschka, Günther; Lehtinen, M.; Pesonen, L. J.; Wasilewski, P. J.

    2006-01-01

    Roč. 87, č. 52 (2006) ISSN 0096-3941. [2006 American Geophysical Union Fall Meeting. 11.12.2006-15.12.2006, San Francisco] Institutional research plan: CEZ:AV0Z30130516 Keywords : magnetic susceptibility * Neuschwanstein * daubreelite Subject RIV: DE - Earth Magnetism, Geodesy, Geography

  2. Anisotropy of out-of-phase magnetic susceptibility of rocks as a tool for direct determination of magnetic sub-fabrics of some minerals

    Czech Academy of Sciences Publication Activity Database

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

    2015-01-01

    Roč. 17 (2015), s. 5321-5321 ISSN 1029-7006. [EGU General Assembly. 17.4.2015-22.4.2015, Vienna] Institutional support: RVO:67985831 Keywords : palaeomagnetism * magnetic susceptibility * minerals Subject RIV: DE - Earth Magnetism, Geodesy, Geography http://meetingorganizer.copernicus.org/EGU2015/EGU2015-5321.pdf

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-09-30

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

  4. Exploiting the Temperature Dependence of Magnetic Susceptibility to Control Convection in Fundamental Studies of Solidification Phenomena

    Science.gov (United States)

    Seybert, C. D.; Evans, J. W.; Leslie, Fred; Jones, W. K., Jr.

    2000-01-01

    It is well known that convection is a dominant mass transport mechanism when materials are solidified on Earth's surface. This convection is caused by gradients in density (and therefore gravitational force) that are brought about by gradients in temperature, composition or both. Diffusion of solute is therefore dwarfed by convection and the study of fundamental parameters, such as dendrite tip shape and growth velocity in the absence of convection is nearly impossible. Significant experimental work has therefore been carried out in orbiting laboratories with the intent of minimizing convection by minimizing gravity. One of the best known experiments of this kind is the Isothermal Dendritic Growth Experiment (IDGE), supported by NASA. Naturally such experiments are costly and one objective of the present investigation is to develop an experimental method whereby convection can be- halted, in solidification and other experiments, on the surface. A second objective is to use the method to minimize convection resulting from the residual accelerations suffered by experiments in microgravity. The method to be used to minimize convection relies on the dependence of the magnetic susceptibility of a fluid on temperature or composition (whichever is driving convection). All materials experience a force when placed in a magnetic field gradient. The direction and magnitude of that force depend on the magnetic susceptibility of the material. Consequently the force will vary if the susceptibility varies with temperature or composition. With a magnetic field gradient in the right direction (typically upward) and of the right magnitude, this variation in the magnetic force can be made to exactly cancel the variation in the gravitational force. Expressed another way, normal buoyancy is exactly countered by a "magnetic buoyancy". To demonstrate the principle, a solution of MnC12 in water has been used. First the variation of the susceptibility of this paramagnetic solution with

  5. 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.

  6. 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.

  7. Anisotropy of Magnetic Susceptibility Studies in Lava Flows of the Eastern Anatolia Region, Turkey

    Science.gov (United States)

    Ucar, Hakan; Cengiz Cinku, Mualla

    2017-04-01

    Eastern Anatolia comprises one of the high plateaus of the Alpine-Himalaya mountain belt with an average elevation of 2 km above the sea level. Available geochronologic data indicate that the volcanism started in the south of the region around the north of Lake Van and continued towards the norths in a age interval of 15.0 Ma to 0.4 Ma. The products are exposed as stratovolcanoes like Agri, Tendurek, Suphan and Girekol with the eruption of andesitic to rhyolitic lavas, ignimbrites and basaltic lava flows. In this study, anisotropy of magnetic susceptibility measurements were carried out on different lava flows (Tendurek, Girekol and Suphan) to determine the flow direction of lavas. It has been shown that the direction of maximum susceptibility is associated with magma flow direction in the vertical direction, while a horizontal flow direction is predicted for the volcano structure of Suphan. Anisotropy of magnetic measurements show a trend of lineation towards the center of the projection and shallow-dipping foliations which are largely scattered.

  8. 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.

  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. 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)

  11. Nanocrystalline GdAlO{sub 3}: XPS, EPR and magnetic susceptibility studies

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, Dimitar [University of Food Technologies, Department of Inorganic and Physical Chemistry, Plovdiv (Bulgaria)

    2011-09-15

    Nanocrystalline gadolinium monoaluminate (GdAlO{sub 3}) has been synthesized by sol-gel method after sintering the precursor gel at 950 C. The microstructural features have been proved by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray analysis (EDX). The XRD pattern confirms the formation of single-phase GdAlO{sub 3} while EDX shows that this nanomaterial is stoichiometric; the average size of the nanoparticles is 40 nm. X-ray photoelectron spectroscopy (XPS) has been used to study the chemical composition and bonding in the as-prepared samples. The binding energies of core-level electrons in Gd, Al and O in GdAlO{sub 3} nanopowder have been found slightly shifted compared to the corresponding values of the same elements. The electron paramagnetic resonance (EPR) spectra at 9.23 GHz (X-band) and different temperatures indicate the existence of magnetically concentrated solid containing Gd{sup 3+} ions. Neel temperature, T{sub N} =3.993 K, effective Bohr magneton number, {mu} {sub eff}=8.18, and constant of magnetic exchange interaction, J{sub ex}=-0.069 cm {sup -1}, have been determined from DC magnetic susceptibilities measured in the range 2-300 K. (orig.)

  12. Magnetic susceptibility of spider webs as a proxy of airborne metal pollution.

    Science.gov (United States)

    Rachwał, Marzena; Rybak, Justyna; Rogula-Kozłowska, Wioletta

    2018-03-01

    The purpose of this pilot study was to test spider webs as a fast tool for magnetic biomonitoring of air pollution. The study involved the investigation of webs made by four types of spiders: Pholcus phalangioides (Pholcidae), Eratigena atrica and Agelena labirynthica (Agelenidae) and Linyphia triangularis (Linyphiidae). These webs were obtained from outdoor and indoor study sites. Compared to the clean reference webs, an increase was observed in the values of magnetic susceptibility in the webs sampled from both indoor and outdoor sites, which indicates contamination by anthropogenically produced pollution particles that contain ferrimagnetic iron minerals. This pilot study has demonstrated that spider webs are able to capture particulate matter in a manner that is equivalent to flora-based bioindicators applied to date (such as mosses, lichens, leaves). They also have additional advantages; for example, they can be generated in isolated clean habitats, and exposure can be monitored in indoor and outdoor locations, at any height and for any period of time. Moreover, webs are ubiquitous in an anthropogenic, heavily polluted environment, and they can be exposed throughout the year. As spider webs accumulate pollutants to which humans are exposed, they become a reliable source of information about the quality of the environment. Therefore, spider webs are recommended for magnetic biomonitoring of airborne pollution and for the assessment of the environment because they are non-destructive, low-cost, sensitive and efficient. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Superspin relaxation in Fe3O4/hexane magnetic fluids: A dynamic susceptibility study

    Science.gov (United States)

    Botez, Cristian E.; Morris, Joshua L.; Eastman, Michael P.

    2012-07-01

    We have used frequency-resolved (100 Hz < f < 10,000 Hz) ac magnetic susceptibility measurements to directly determine the Néel and Brown relaxation times in 30-nm-size Fe3O4/hexane magnetic fluids at temperatures between 200 and 300 K. Our data collected on both powder and magnetic fluid samples allow the separation of the contributions from the Néel and Brown relaxation mechanisms that act concomitantly within the above-mentioned temperature range. At all temperatures we find that the Brown relaxation times (τB) are shorter than their Néel counterparts (τN), evidence that the Brown mechanism yields the major contribution towards the system's overall superspin dynamics. τB exhibits a steep two-order-of-magnitude decrease upon heating, from τB = 1 × 10-3 s at T = 237 K to τB = 1.5 × 10-5 s at T = 270 K, a behavior mostly driven by the heating-induced reduction of the liquid carrier's viscosity.

  14. 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.

  15. 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.

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

    Science.gov (United States)

    Chen, Yuan-Tsung; Lin, Sung-Hao; Sheu, Tzer-Shin

    2014-01-02

    In this investigation, the low-frequency alternate-current (AC) magnetic susceptibility (χ ac ) and hysteresis loop of various MgO thickness in CoFeB/MgO/CoFeB magnetic tunneling junction (MTJ) determined coercivity ( H c ) and magnetization ( M s ) and correlated that with χ ac 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 χ ac and maximum phase angle (θ max ) at the optimal resonance frequency ( f res ), at which the spin sensitivity is maximal. The results reveal that χ ac falls as the frequency increases due to the relationship between magnetization and thickness of the barrier layer. The maximum χ ac 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 χ ac and maximum phase angle. The corresponding maximum of χ ac is related to high exchange coupling. High coercivity and saturation magnetization contribute to high exchange-coupling χ ac strength.

  17. 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.

  18. 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)

  19. 1D magnetic interactions in Cu(II) oxovanadium phosphates (VPO), magnetic susceptibility, DFT, and single-crystal EPR.

    Science.gov (United States)

    Venegas-Yazigi, Diego; Spodine, Evgenia; Saldias, Marianela; Vega, Andrés; Paredes-García, Verónica; Calvo, Rafael; de Santana, Ricardo Costa

    2015-04-20

    We report the crystal face indexing and molecular spatial orientation, magnetic properties, electron paramagnetic resonance (EPR) spectra, and density functional theory (DFT) calculations of two previously reported oxovanadium phosphates functionalized with Cu(II) complexes, namely, [Cu(bipy)(VO2)(PO4)]n (1) and [{Cu(phen)}2(VO2(H2O)2)(H2PO4)2 (PO4)]n (2), where bipy = 2,2'-bipyridine and phen = 1,10-phenanthroline, obtained by a new synthetic route allowing the growth of single crystals appropriate for the EPR measurements. Compounds 1 and 2 crystallize in the triclinic group P1̅ and in the orthorhombic Pccn group, respectively, containing dinuclear copper units connected by two -O-P-O- bridges in 1 and by a single -O-P-O- bridge in 2, further connected through -O-P-O-V-O- bridges. We emphasize in our work the structural aspects related to the chemical paths that determine the magnetic properties. Magnetic susceptibility data indicate bulk antiferromagnetism for both compounds, allowing to calculate J = -43.0 cm(-1) (dCu-Cu = 5.07 Å; J defined as Hex(i,j) = -J Si·Sj), considering dinuclear units for 1, and J = -1.44 cm(-1) (dCu-Cu = 3.47 Å) using the molecular field approximation for 2. The single-crystal EPR study allows evaluation of the g matrices, which provide a better understanding of the electronic structure. The absence of structure of the EPR spectra arising from the dinuclear character of the compounds allows estimation of weak additional exchange couplings |J'| > 0.3 cm(-1) for 1 (dCu-Cu = 5.54 Å) and a smaller value of |J'| ≥ 0.15 cm(-1) for 2 (dCu-Cu = 6.59 Å). DFT calculations allow evaluating two different exchange couplings for each compound, specifically, J = -36.60 cm(-1) (dCu-Cu = 5.07 Å) and J' = 0.20 cm(-1) (dCu-Cu =5.54 Å) for 1 and J = -1.10 cm(-1) (dCu-Cu =3.47 Å) and J' = 0.01 cm(-1) (dCu-Cu = 6.59 Å) for 2, this last value being in the range of the uncertainties of the calculations. Thus, these values are in good agreement

  20. 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

  1. A comparative quantitative analysis of magnetic susceptibility artifacts in echo planar and PROPELLER diffusion-weighted images

    Science.gov (United States)

    Cho, Jae-Hwan; Lee, Hae-Kag; Yang, Han-Joon; Lee, Gui-Won; Park, Yong-Soon; Chung, Woon-Kwan

    2013-01-01

    In this study, the authors investigated whether periodically-rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) diffusion-weighted imaging (DWI) can remove magnetic susceptibility artifacts and compared apparent diffusion coefficient (ADC) values for PROPELLER DWI and the common echo planar (EP) DWI. Twenty patients that underwent brain MRI with a metal dental implant were selected. A 3.0T MR scanner was then used to obtain EP DWI, PROPELLER DWI, and corresponding apparent diffusion coefficient (ADC) maps for a b-value of 0 and 1,000 s/mm2. The frequencies of magnetic susceptibility artifacts in four parts of the brain (bilateral temporal lobes, pons, and orbit) were selected. In the ADC maps, we measured the ADC values of both sides of the temporal lobe and the pons. According to the study results, the frequency of magnetic susceptibility artifacts in PROPELLER DW images was lower than it was in EP DW images. In ADC maps, the ADC values of the bilateral temporal lobes and the pons were all higher in PROPELLER ADC maps than in EP ADC maps. Our findings show that when a high-field MRI machine is used, magnetic susceptibility artifacts can distort anatomical structures and produce high-intensity signals. Furthermore, our findings suggest that in many cases, PROPELLER DWI would be helpful in terms of achieving a correct diagnosis.

  2. 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

  3. Understanding the Morphological Mismatch between Magnetic Susceptibility Source and T2 Image

    Directory of Open Access Journals (Sweden)

    Zikuan Chen

    2013-01-01

    Full Text Available Background and Purpose Recent research has shown that a T2 * image (either magnitude or phase is not identical to the internal spatial distribution of a magnetic susceptibility (χ source. In this paper, we examine the reasons behind these differences by looking into the insights of T2 * -weighted magnetic resonance imaging (T2 * MRI and provide numerical characterizations of the source/image mismatches by numerical simulations. Methods For numerical simulations of T2 * MRI, we predefine a 3D χ source and calculate the complex-valued T2 * image by intravoxel dephasing in presence and absence of diffusion. We propose an empirical α-power model to describe the overall source/image transformation. For a Gaussian-shaped χ source, we numerically characterize the source/image morphological mismatch in terms of spatial correlation and FWHM (full width at half maximum. Results In theory, we show that the χ-induced fieldmap is morphologically different from the χ source due to dipole effect, and the T2 * magnitude image is related to the fieldmap by a quadratic transformation in the small phase angle regime, which imposes an additional morphological change. The numerical simulations with a Gaussian-shaped χ source show that a T2 * magnitude image may suffer an overall source/image morphological shrinkage of 20% to 25% and that the T2 * phase image is almost identical to the fieldmap thus maintaining a morphological mismatch from the χ source due to dipole effect. Conclusion The morphological mismatch between a bulk χ source and its T2 * image is caused by the 3D convolution during tissue magnetization (dipole effect, the nonlinearity of the T2 * magnitude and phase calculation, and the spin diffusion effect. In the small phase angle regime, the T2 * magnitude exhibits an overall morphological shrinkage, and the T2 * phase image suffers a dipole effect but maintains the χ-induced fieldmap morphology.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. Impact of organic carbon and iron bioavailability on the magnetic susceptibility of soils

    Science.gov (United States)

    Porsch, Katharina; Rijal, Moti L.; Borch, Thomas; Troyer, Lyndsay D.; Behrens, Sebastian; Wehland, Florian; Appel, Erwin; Kappler, Andreas

    2014-03-01

    Microorganisms are known to couple the degradation of hydrocarbons to Fe(III) reduction leading to the dissolution and (trans)formation of Fe minerals including ferro(i)magnetic Fe minerals such as magnetite. The screening of soil magnetic properties, in particular magnetic susceptibility (MS), has the potential to assist in locating and assessing hydrocarbon (e.g. gasoline) contamination in the environment. In order to evaluate this, it must be understood how changes in soil geochemistry and hydrocarbon input impact MS. To this end, we incubated microcosms with soils from six different field sites anoxically and followed the changes in soil MS. In parallel we simulated hydrocarbon (i.e., gasoline) contamination in the same soils under anoxic conditions. We found that in microbially active microcosms both with or without added gasoline, average changes in MS of 6.9 ± 2.6% occurred, whereas in sterile controls the changes were less than 2.5% demonstrating that microbial metabolism played a major role in the (trans)formation of ferro(i)magnetic minerals. The microcosms reached stable MS values after a few weeks to months in four out of the six soils showing an increase in MS while in two soils the MS decreased over time. After stable MS values were reached, further addition of labile organic carbon (i.e., lactate/acetate) did not lead to further changes in MS, but the addition of Fe(III) oxyhydroxides (ferrihydrite) led to increases in MS suggesting that the changes in MS were limited by bioavailable Fe and not by bioavailable organic carbon. In the control experiments without carbon amendment, we observed that natural organic matter was mobilized from the soil matrix by water or microbial growth medium (0.33-0.47 mL/g field moist soil) added to the microcosms, and that this mobilized organic matter also stimulated microbial Fe metabolism and thus also led to a microbially driven change in MS. This study shows that changes in MS after an increase of the amount of

  9. Linking Anisotropy of Magnetic Susceptibility (AMS) to transport direction: The Gavarnie Thrust, Axial Zone, Pyrenees

    Science.gov (United States)

    Marcén, Marcos; Casas-Sainz, Antonio; Román-Berdiel, Teresa; Soto, Ruth; Oliva-Urcía, Belén

    2017-04-01

    This work deals with the application of the anisotropy of magnetic susceptibility (AMS), structural analysis and microstructural analysis to the study of shear zones. Mylonitized fault rocks have been sampled in the Gavarnie Trust, one of the main structures of the Pyrenean Axial Zone, which was structured as a south-verging antiformal stack during the Alpine Orogeny. In the studied area, the Gavarnie Unit (Silurian-Carboniferous, low grade metasedimentary rocks) overthrust the Millares and Bielsa Units (Permian and Cretaceous cover, Cambro-Ordovician medium grade metamorphic rocks and granitoids), with a minimum horizontal displacement of 12km. Three profiles of the shear zone were studied with the goal of observing changes in the transport direction, the strain distribution and the orientation of the magnetic ellipsoid., One profile is parallel to the basal thrust plane, where the core zone has been identified, and the other two are vertical transects (profiles 1 and 2), perpendicular to the thrust plane. The shear zone, developed into the hangingwall phyllitic Silurian and Devonian units, is at least 30 m wide. The structural analysis reveals that the Silurian rocks are the local detachment level, which becomes thinner and pinchs out completely towards the South, where the detachment level is within the Devonian units (Fourche de la Sede Fm.). In both vertical profiles, the shear zone shows a decrease in the strain from the contact with the Cretaceous limestones at the footwall, towards the upper limit of the shear zone. This is evidenced by the lower development of mylonitic foliations and SCC' structures and the upwards increase of brittle deformation. The transport direction inferred from SC structures (stretching lineations in S and C planes) is constant in all sites, with an average of N190E. AMS data are in perfect agreement with the structural analysis, being the magnetic foliation parallel to the S or C planes of the SC structures. The magnetic

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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

  15. Magnetothermal Convection of Water with the Presence or Absence of a Magnetic Force Acting on the Susceptibility Gradient.

    Science.gov (United States)

    Maki, Syou

    2016-01-01

    Heat transfer of magnetothermal convection with the presence or absence of the magnetic force acting on the susceptibility gradient (fsc) was examined by three-dimensional numerical computations. Thermal convection of water enclosed in a shallow cylindrical vessel (diameter over vessel height = 6.0) with the Rayleigh-Benard model was adopted as the model, under the conditions of Prandtl number 6.0 and Ra number 7000, respectively. The momentum equations of convection were nondimensionalized, which involved the term of fsc and the term of magnetic force acting on the magnetic field gradient (fb). All the computations resulted in axisymmetric steady rolls. The values of the averaged Nu, the averaged velocity components U, V, and W, and the isothermal distributions and flow patterns were almost completely the same, regardless of the presence or absence of the term of fsc. As a result, we found that the effect of fsc was extremely small, although much previous research emphasized the effect with paramagnetic solutions under an unsteady state. The magnitude of fsc depends not only on magnetic conditions (magnitudes of magnetic susceptibility and magnetic flux density), but also on the thermal properties of the solution (thermal conductivity, thermal diffusivity, and viscosity). Therefore the effect of fb becomes dominant on the magnetothermal convection. Active control over the density gradient with temperature will be required to advance heat transfer with the effect of fsc.

  16. Magnetothermal Convection of Water with the Presence or Absence of a Magnetic Force Acting on the Susceptibility Gradient.

    Directory of Open Access Journals (Sweden)

    Syou Maki

    Full Text Available Heat transfer of magnetothermal convection with the presence or absence of the magnetic force acting on the susceptibility gradient (fsc was examined by three-dimensional numerical computations. Thermal convection of water enclosed in a shallow cylindrical vessel (diameter over vessel height = 6.0 with the Rayleigh-Benard model was adopted as the model, under the conditions of Prandtl number 6.0 and Ra number 7000, respectively. The momentum equations of convection were nondimensionalized, which involved the term of fsc and the term of magnetic force acting on the magnetic field gradient (fb. All the computations resulted in axisymmetric steady rolls. The values of the averaged Nu, the averaged velocity components U, V, and W, and the isothermal distributions and flow patterns were almost completely the same, regardless of the presence or absence of the term of fsc. As a result, we found that the effect of fsc was extremely small, although much previous research emphasized the effect with paramagnetic solutions under an unsteady state. The magnitude of fsc depends not only on magnetic conditions (magnitudes of magnetic susceptibility and magnetic flux density, but also on the thermal properties of the solution (thermal conductivity, thermal diffusivity, and viscosity. Therefore the effect of fb becomes dominant on the magnetothermal convection. Active control over the density gradient with temperature will be required to advance heat transfer with the effect of fsc.

  17. Pauli magnetic susceptibility of bilayer graphene and hexagonal boron-nitride

    Energy Technology Data Exchange (ETDEWEB)

    Mousavi, Hamze, E-mail: hamze.mousavi@gmail.com [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of); Jalilvand, Samira [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of); Kurdestany, Jamshid Moradi [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65201 (United States)

    2016-12-01

    We study the contribution of s and p orbitals on the Pauli magnetic susceptibility (PMS) and density of state (DOS) of the following three structures (1) bilayer graphene (2) bilayer boron-nitride (BN) and (3) bilayer graphene-BN within a two-band tight-binding Harrison Hamiltonian and the Green's function technique. It is shown that in all three cases, the contribution of s and p{sub x} or p{sub y} orbitals have no states around the Fermi level, while for bilayer graphene and graphene-BN the total DOS and DOS of p{sub z} orbital appear to be a linear function around this level. We show explicitly that for bilayer BN the contribution of p{sub z} orbital does not have states around the Fermi level, because of ionization energy difference between the boron (B) and nitrogen (N) atoms. We find that the bandwidth of s, p{sub x} or p{sub y} is more extension than case of p{sub z} orbital as a result of the Van-Hove singularities in the DOS. This leads to consideration of the PMS in two, low and high temperature, regions.

  18. Analytical expressions for crystal fields of hexagonal symmetry: high temperature magnetic susceptibility applications

    International Nuclear Information System (INIS)

    Sobral, R.R.; Guimaraes, A.P.; Silva, X.A. da.

    1996-09-01

    This paper discusses the use of Computer Algebra (CA) to obtain analytical results of interest for the studies of magnetic behavior of rare-earth intermetallic compounds, where the CF has hexagonal symmetry. In the first part, CA techniques are applied to obtain the characteristic polynomials of the CF Hamiltonian. A remarkable result is that for most J's the characteristic polynomials are entirely factored, allowing the analytical derivation of the eigenvalues as a function of the CF parameters. A comparison with the values obtained numerically is made for two cases, showing, as expected, excellent agreement. In the second part, a model Hamiltonian containing the CF term and exchange is used, and an expression for the high temperature susceptibility (HTS), suitable for algebraic computation is derived. We compute the HTS expressions using results of the first part plus the partially factored polynomials of the model Hamiltonian. In the molecular field approximation, we re-obtain results of the literature for HTS in the parallel and perpendicular directions. This treatment may be extended to other high anisotropy systems, both hexagonal and rhombohedral, as the nitrided R 2 Fe 17 intermetallic compounds. (author). 13 refs., 2 tabs

  19. 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.)

  20. 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.

  1. 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

  2. Rapid nanoparticle-mediated monitoring of bacterial metabolic activity and assessment of antimicrobial susceptibility in blood with magnetic relaxation.

    Directory of Open Access Journals (Sweden)

    Charalambos Kaittanis

    2008-09-01

    Full Text Available Considering the increased incidence of bacterial infections and the emergence of multidrug resistant bacteria at the global level, we designed superparamagnetic iron oxide nanoparticles as nanosensors for the assessment of antimicrobial susceptibility through magnetic relaxation. In this report, we demonstrate that iron oxide nanosensors, either dextran-coated supplemented with Con A or silica-coated conjugated directly to Con A, can be used for the fast (1 quantification of polysaccharides, (2 assessment of metabolic activity and (3 determination of antimicrobial susceptibility in blood. The use of these polysaccharide nanosensors in the determination of antimicrobial susceptibility in the clinic or the field, and the utilization of these nanoprobes in pharmaceutical R&D are anticipated.

  3. 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.

  4. 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.

  5. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-15

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

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

    Science.gov (United States)

    Baheza, Richard A.; Welch, E. Brian; Gochberg, Daniel F.; Sanders, Melinda; Harvey, Sara; Gore, John C.; Yankeelov, Thomas E.

    2015-01-01

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

  8. 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.

  9. Stratigraphic correlations in mid- to late-Proterozoic carbonates of the Democratic Republic of Congo using magnetic susceptibility

    Science.gov (United States)

    Delpomdor, Franck R. A.; Devleeschouwer, Xavier; Spassov, Simo; Préat, Alain R.

    2017-04-01

    In this paper, we have tested the application of magnetic susceptibility measurements in Cu-Ag-Zn-Pb-(Fe)-mineralized carbonates of the BIe subgroup (Democratic Republic of Congo) as an efficient tool for regional and global high-resolution stratigraphic correlations in the Neoproterozoic marine carbonates. To achieve this goal, we integrate the low-field magnetic susceptibility (XLF) data with facies analyses, geochemistry and isotope stratigraphy. The microfacies analyses of two cores, Tshinyama#S70 and Kafuku#15, drilled in the early Neoproterozoic carbonates of the Mbuji-Mayi Supergroup reveal a deep carbonate ramp setting associated with a microbial/stromatolitic mid-ramp environment. High-resolution stratigraphic correlations using magnetic susceptibility and C-isotope curves established for both cores, 190 km apart, suggest a sedimentary hiatus at the base of the Tshinyama#S70 succession. C-O and Sr isotopes and Sr/Ca and Fe abundances show that a diagenetic meteoric overprint affected the series of the Tshinyama#S70 core and a thermal effect related to mineralizing fluids affected the Kafuku#15 core carbonates.

  10. Evaluation of sclerosis in Modic changes of the spine using susceptibility-weighted magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Böker, Sarah M., E-mail: Sarah-maria.boeker@charite.de [Department of Radiology, Charité, Charitéplatz 1, 10117 Berlin (Germany); Bender, Yvonne Y., E-mail: Yi-na.bender@charite.de [Department of Radiology, Charité, Charitéplatz 1, 10117 Berlin (Germany); Adams, Lisa C., E-mail: Lisa.adams@charite.de [Department of Radiology, Charité, Charitéplatz 1, 10117 Berlin (Germany); Fallenberg, Eva M., E-mail: Eva.fallenberg@charite.de [Department of Radiology, Charité, Augustenburger Platz 1, 13353 Berlin (Germany); Wagner, Moritz, E-mail: Moritz.wagner@charite.de [Department of Radiology, Charité, Charitéplatz 1, 10117 Berlin (Germany); Hamm, Bernd, E-mail: Bernd.hamm@charite.de [Department of Radiology, Charité, Charitéplatz 1, 10117 Berlin (Germany); Makowski, Marcus R., E-mail: Marcus.makowski@charite.de [Department of Radiology, Charité, Charitéplatz 1, 10117 Berlin (Germany)

    2017-03-15

    Highlights: • SWMR allows a reliable detection of sclerosis in Modic changes. • SWI has a better accuracy for detection of sclerosis in Modic changes than T1/T2w MR. • By applying SWMR the use of additional CT/radiography can be minimized. - Abstract: Purpose: To evaluate the diagnostic performance of susceptibility-weighted magnetic resonance imaging (SWMR) for the differentiation of sclerotic and non-sclerotic Modic changes (MC) of the spine compared to computed tomography (CT) and radiographs. Materials and methods: The Institutional Ethics-Review-Board approved this prospective study in advance. Written consent was obtained from all subjects. SWMR and standard T1/T2 MR of the cervical (n = 21) and/or lumbar spine (n = 34) were performed in 54 patients. 21 patients served as control. 18 patients were evaluated with CT; in all other patients radiographs were available. 67 Modic changes were identified on T1/T2 MR. On SWMR changes were classified as sclerotic and non-sclerotic based on signal intensity measurements. The sensitivity and specificity of SWMR and T1/T2 MR for differentiating between sclerotic and non-sclerotic Modic changes were determined with CT and radiographs as reference standard. Results: On SWMR, signal measurements between sclerotic and non-sclerotic Modic changes differed significantly (p < 0.01). On T1- and T2-weighted MR no significant difference (p > 0.05) was measured. On SWMR, a reliable differentiation between sclerotic and non-sclerotic Modic changes could be achieved, with a sensitivity of 100% and specificity of 95%. In contrast, the combination of T1-/T2-weighted MR yielded a significantly lower sensitivity to detect sclerosis (20%). Conclusion: SWMR allows a reliable detection of sclerosis in Modic changes with a higher accuracy compared to standard spine MR sequences, using radiographs and CT as reference standard.

  11. Laboratory Investigation of Complex Conductivity and Magnetic Susceptibility on Natural Iron Oxide Coated Sand

    Science.gov (United States)

    Wang, C.; Slater, L. D.; Day-Lewis, F. D.; Briggs, M. A.

    2017-12-01

    Redox reactions occurring at the oxic/anoxic interface where groundwater discharges to surface water commonly result in iron oxide deposition that coats sediment grains. With relatively large total surface area, these iron oxide coated sediments serve as a sink for sorption of dissolved contaminants, although this sink may be temporary if redox conditions fluctuate with varied flow conditions. Characterization of the distribution of iron oxides in streambed sediments could provide valuable understanding of biogeochemical reactions and the ability of a natural system to sorb contaminants. Towards developing a field methodology, we conducted laboratory spectral induced polarization (SIP) and magnetic susceptibility (MS) measurements on natural iron oxide coated sand (Fe-sand) with grain sizes ranging from 0.3 to 2.0 mm in order to assess the sensitivity of these measurements to iron oxides in sediments. The Fe-sand was also sorted by sieving into various grain sizes to study the impact of grain size on the polarization mechanisms. The unsorted Fe-sand saturated with 0.01 S/m NaCl solution exhibited a distinct phase response ( > 4 mrad) in the frequency range from 0.001 to 100 Hz whereas regular silica sand was characterized by a phase response less than 1 mrad under the same conditions. The presence of iron oxide substantially increased MS (3.08×10-3 SI) over that of regular sand ( < 10-5 SI). An increase of both phase peak and relaxation time was found with increasing grain size of the sorted Fe-sand. Laboratory results demonstrated that SIP and MS may be well suited to mapping the distribution of iron oxides in streambed sediments associated with anoxic groundwater discharge.

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

    Science.gov (United States)

    Chen, Zikuan; Calhoun, Vince D

    2016-03-01

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

  13. 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.

  14. 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.

  15. Temperature dependence of the magnetic volume susceptibility of human breast fat tissue: an NMR study

    NARCIS (Netherlands)

    Sprinkhuizen, S.M.; Bakker, C.J.G.; Ippel, J.H.; Boelens, R.; Viergever, M.A.; Bartels, L.W.

    2012-01-01

    Object Proton resonance frequency shift (PRFS)-based MR thermometry (MRT) is hampered by heat-induced susceptibility changes when applied in tissues containing fat, e.g., the human breast. In order to assess the impact of fat susceptibility changes on PRFS-based MRT during thermal therapy in the

  16. 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

  17. 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)

  18. Phonon effect on the temperature dependence of spin susceptibility and magnetization in metals

    Energy Technology Data Exchange (ETDEWEB)

    Kim, D.J.; Tanaka, C.; Ukon, S.

    1985-06-01

    In many transition metals the paramagnetic spin susceptibility X increases with increasing temperature much beyond ordinary theories could account for. We demonstrate how the effect of the electron-phonon interactions enable us to understand such temperature dependence of X.

  19. 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)

  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. 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

  2. Magnetic susceptibility and specific heat of uranium double perovskite oxides Ba2 MUO6 (M=Co, Ni)

    International Nuclear Information System (INIS)

    Hinatsu, Yukio; Doi, Yoshihiro

    2006-01-01

    Double perovskites Ba 2 MUO 6 (M=Co, Ni) were prepared by the solid-state reaction. X-ray diffraction measurements show that both cobalt (nickel) and uranium ions are ordered in the NaCl type over the six-coordinate B sites of the perovskite ABO 3 . Detailed magnetic susceptibility and specific heat measurements show that Ba 2 CoUO 6 and Ba 2 NiUO 6 order ferromagnetically at 9.1 and 25 K, respectively. From the analysis of the magnetic specific heat, the ground states of the Co 2+ and Ni 2+ ions were determined. - Graphical abstract: The crystal structure for Ba 2 CoUO 6 and Ba 2 NiUO 6 . They crystallize in the cubic double perovskite-type structure and order ferromagnetically at 9.1 and 25 K, respectively

  3. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

    Malkin, B Z; Zakirov, A R [Kazan State University, Kazan 420008 (Russian Federation); Lummen, T T A; Van Loosdrecht, P H M [Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen (Netherlands); Dhalenne, G, E-mail: boris.malkin@ksu.r [Laboratoire de Physico-Chimie de L' Etat Solide, ICMMO, UMR 8182, Universite Paris-Sud, 91405 Orsay (France)

    2010-07-14

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

  5. Erythrocyte enrichment in hematopoietic progenitor cell cultures based on magnetic susceptibility of the hemoglobin.

    Directory of Open Access Journals (Sweden)

    Xiaoxia Jin

    Full Text Available Using novel media formulations, it has been demonstrated that human placenta and umbilical cord blood-derived CD34+ cells can be expanded and differentiated into erythroid cells with high efficiency. However, obtaining mature and functional erythrocytes from the immature cell cultures with high purity and in an efficient manner remains a significant challenge. A distinguishing feature of a reticulocyte and maturing erythrocyte is the increasing concentration of hemoglobin and decreasing cell volume that results in increased cell magnetophoretic mobility (MM when exposed to high magnetic fields and gradients, under anoxic conditions. Taking advantage of these initial observations, we studied a noninvasive (label-free magnetic separation and analysis process to enrich and identify cultured functional erythrocytes. In addition to the magnetic cell separation and cell motion analysis in the magnetic field, the cell cultures were characterized for cell sedimentation rate, cell volume distributions using differential interference microscopy, immunophenotyping (glycophorin A, hemoglobin concentration and shear-induced deformability (elongation index, EI, by ektacytometry to test for mature erythrocyte attributes. A commercial, packed column high-gradient magnetic separator (HGMS was used for magnetic separation. The magnetically enriched fraction comprised 80% of the maturing cells (predominantly reticulocytes that showed near 70% overlap of EI with the reference cord blood-derived RBC and over 50% overlap with the adult donor RBCs. The results demonstrate feasibility of label-free magnetic enrichment of erythrocyte fraction of CD34+ progenitor-derived cultures based on the presence of paramagnetic hemoglobin in the maturing erythrocytes.

  6. 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

  7. Methods for the computation of templates from quantitative magnetic susceptibility maps (QSM): Toward improved atlas- and voxel-based analyses (VBA).

    Science.gov (United States)

    Hanspach, Jannis; Dwyer, Michael G; Bergsland, Niels P; Feng, Xiang; Hagemeier, Jesper; Bertolino, Nicola; Polak, Paul; Reichenbach, Jürgen R; Zivadinov, Robert; Schweser, Ferdinand

    2017-11-01

    To develop and assess a method for the creation of templates for voxel-based analysis (VBA) and atlas-based approaches using quantitative magnetic susceptibility mapping (QSM). We studied four strategies for the creation of magnetic susceptibility brain templates, derived as successive extensions of the conventional template generation (CONV) based on only T 1 -weighted (T 1 w) images. One method that used only T 1 w images involved a minor improvement of CONV (U-CONV). One method used only magnetic susceptibility maps as input for template generation (DIRECT), and the other two used a linear combination of susceptibility and T 1 w images (HYBRID) and an algorithm that directly used both image modalities (MULTI), respectively. The strategies were evaluated in a group of N = 10 healthy human subjects and semiquantitatively assessed by three experienced raters. Template quality was compared statistically via worth estimates (WEs) obtained with a log-linear Bradley-Terry model. The overall quality of the templates was better for strategies including both susceptibility and T 1 w contrast (MULTI: WE = 0.62; HYBRID: WE = 0.21), but the best method depended on the anatomical region of interest. While methods using only one modality resulted in lower WEs, lowest overall WEs were obtained when only T 1 w images were used (DIRECT: WE = 0.12; U-CONV: WE = 0.05). Template generation strategies that employ only magnetic susceptibility contrast or both magnetic susceptibility and T 1 w contrast produce templates with the highest quality. The optimal approach depends on the anatomical structures of interest. The established approach of using only T 1 w images (CONV) results in reduced image quality compared to all other approaches studied. 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2017;46:1474-1484. © 2017 International Society for Magnetic Resonance in Medicine.

  8. Out-of-phase susceptibility and viscous magnetization: alternative tools for magnetic granulometry of sediments and soils

    Czech Academy of Sciences Publication Activity Database

    Chadima, Martin

    2016-01-01

    Roč. 6, Special issue (2016) ISSN 2007-9656. [Biennial Meeting Latinmag /4./. 23.11.2015-27.11.2015, Sao Paulo] Institutional support: RVO:67985831 Keywords : palaeomagnetism * sediments * soils Subject RIV: DE - Earth Magnetism, Geodesy, Geography http://www. geofisica .unam.mx/LatinmagLetters/LL16-01-SP/D/D07.pdf

  9. [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.

  10. 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.

  11. 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

  12. 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

  13. The relation between anisotropy of magnetic susceptibility (AMS) and mineral filling of foraminifers

    Science.gov (United States)

    Guzhikova, Anastasia; Grishchenko, Vladimir; Surinsky, Arseny; Tselmovich, Vladimir

    2017-04-01

    The comparison of bio- and magnetostratigraphic data in four sections of Jurassic-Cretaceous sediments of Mountain Crimea and Saratov region (Russia) detected the presence of correlation between the AMS parameter T and the amount of foraminifers in rock sample: disk-shaped magnetic particles dominance is connected with high quantity of foraminifers and therefore, cigar-shaped particles signify low foraminifer content. Parameter T (shape parameter) representing the magnetic particle form: T values close to 1 indicate the plain (disc-shaped) form of magnetic particles, T values close to (-1) highlight the prolate (cigar-shaped) form. To understand the nature of this interrelation a few disc-shaped foraminifers were studied using microprobe analysis. The results of this study have shown that inner spaces of foraminifers are completely filled by pyrite, which grains are covered with thin magnetite tape (the thickness of the tape is less than 200 nanometers). We suppose that this magnetite tape provides the main influence to anisotropy's character. In the Maastrichtian of Mountain Crimea the relation between AMS and amount of foraminifers appears to be more significant after the heating of samples in the muffle furnace till 500°C during 1 hour. Primary magnetic texture was nearly chaotic, but after the heating it acquired the view peculiar to rocks containing plain ferromagnetic particles, formed in calm hydrodynamic environment. This event may be explained by transition (at the temperature of 450°C) of non-magnetic pyrite, fulfilling the inner structure of foraminifers, to the high-magnetic magnetite. The relations between petromagnetic parameters and special aspects of micropaleontological complexes involve studies that are more special because they gain much interest and perspectives in the area of sedimentological and paleoecological reconstructions. The finance part of the study was supported by RFBR: Russian Foundation for Basic Research (projects №№ 16

  14. Magnetic susceptibility of optimally doped HgBa2CuO4 +δ

    Science.gov (United States)

    Itoh, Yutaka; Machi, Takato; Yamamoto, Ayako

    2017-12-01

    The magnitude of the powder spin susceptibility of an optimally doped superconductor HgBa2CuO4 +δ (Hg1201) in the normal state is found to be nearly the same as that of La2 -xSrxCuO4 near the optimally doped level. The Stoner enhancement factor of Hg1201 is larger than that of La2 -xSrxCuO4 . The magnitude correlation of the Stoner enhancement factor is inconsistent with the effect of the recent theoretical Coulomb repulsion between 3 d electrons and that of the superexchange interaction of a charge transfer type.

  15. Using magnetic susceptibility mapping for assessing soil degradation due to water erosion

    Czech Academy of Sciences Publication Activity Database

    Jakšík, O.; Kodešová, R.; Kapička, Aleš; Klement, A.; Fér, M.; Nikodém, A.

    2016-01-01

    Roč. 11, č. 2 (2016), s. 105-113 ISSN 1801-5395 R&D Projects: GA MZe QJ1230319 Institutional support: RVO:67985530 Keywords : arable land * geomorphologically diverse areas * Chernozem Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.934, year: 2016

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

    Science.gov (United States)

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

    1999-06-01

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

  17. Contribution of magnetic susceptibility effects to transmembrane chemical shift differences in the 31P NMR spectra of oxygenated erythrocyte suspensions

    International Nuclear Information System (INIS)

    Kirk, K.; Kuchel, P.W.

    1988-01-01

    Triethyl phosphate, dimethyl methylphosphonate, and the hypophosphite ion all contain the phosphoryl functional group. When added to an oxygenated erythrocyte suspension, the former compound gives rise to a single 31 P NMR resonance, whereas the latter compounds give rise to separate intra- and extracellular 31 P NMR resonances. On the basis of experiments with intact oxygenated cell suspensions (in which the hematocrit was varied) and with oxygenated cell lysates (in which the lysate concentration was varied) it was concluded that the chemical shifts of the intra- and extracellular populations of triethyl phosphate differ as a consequence of the diamagnetic susceptibility of intracellular oxyhemoglobin but that this difference is averaged by the rapid exchange of the compound across the cell membrane. The difference is the magnetic susceptibility of the intra- and extracellular compartments contributes to the observed separation of the intra- and extracellular resonances of dimethyl methylphosphonate and hypophosphite. The magnitude of this contribution is, however, substantially less than that calculated using a simple two-compartment model and varies with the hematocrit of the suspension. Furthermore, it is insufficient to fully account for the transmembrane chemical shift differences observed for dimethyl methylphosphonate and hypophosphite. An additional effect is operating to move the intracellular resonances of these compounds to a lower chemical shift. The effect is mediated by an intracellular component, and the magnitude of the resultant chemical shift variations depends upon the chemical structure of the phosphoryl compound involved

  18. Anisotropy of magnetic susceptibility analysis of the Cantera Ignimbrite, San Luis Potosi, México: flow source recognition

    Science.gov (United States)

    Caballero-Miranda, C. I.; Torres-Hernández, J. R.; Alva-Valdivia, L. M.

    2009-01-01

    Anisotropy of magnetic susceptibility (AMS) was selected as the key technique to find the source of the widespread Cantera Ignimbrite and to seek its possible relationship with the San Luis Potosí Caldera. Eighteen sites (372 specimens from 155 cores) from the Oligocene Cantera Ignimbrite were sampled. AMS was measured on a KLY2 Kappabridge. AMS data were processed with Anisoft 3 software using Jelinek statistics as well as `SpheriStat' principal components and density distribution. Mean susceptibilities range from 290 to 5026 × 10-6 SI (average = 2526 × 10-6 SI). The anisotropy degree ( P j) ranges from 1.005 to 1.055, with only one site displaying a value of 1.134 ( P j average = 1.031). AMS ellipsoid shapes are mostly oblate, with the T-factor ranging from 0.843 to 0.144 ( T average = 0.529), although one site is mainly prolate ( T = -0.005), and three additional sites have an important proportion of prolate specimens. Magnetic fabrics of most sites shows k3 axes around nearly circular distributions and k 1- k 2 axes around elongated-girdle distributions defining sub-horizontal foliation planes; exceptions to this are related to sites with a significant percentage of prolate specimens. Flow directions inferred from AMS analysis indicate several ignimbrite sources located along selected NW-SE linear features (faults and fractures such as El Potosino Fault) as well as along the rim of the caldera structure. The geometry of volcanic outcrops, the NW-SE faulting-fracture system, as well as the AMS results suggest that this is a caldera structure resembling the trapdoor-type (Lipman, 1997).

  19. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-09-15

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

  1. 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.

  2. 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

  3. High-Resolution Magnetic Susceptibility Stratigraphy Spanning Late Devonian Global Change from a New Scientific Drillcore in Canning Basin, Northwest Australia

    Science.gov (United States)

    Diamond, M. R.; Raub, T. D.; Kirschvink, J. L.; Playton, T. E.; Hocking, R. M.; Haines, P.; Tulipani, S.

    2010-12-01

    New shallow scientific drillcore has been recovered through the Frasnian-Famennian extinction boundary in northwest Australia’s Canning Basin. Previous work in the McWhae Ridge outcrop belt has identified patterns of turnover in trilobites and other fauna, change from sponge- and coral-dominated reefs to post-extinction microbial-dominated reefs, apparent sea level changes, and carbon isotopic evidence of late Devonian crisis. Continuous magnetic susceptibility (MS) stratigraphy yields highly structured oscillations spanning ~42 m of reef-slope carbonate. These oscillations appear to identify late Frasnian “Kellwasser” events and they may record sedimentary response to orbital variations, establishing a high-resolution relative chronostratigraphy of late Devonian global change. Magnetic susceptibility stratigraphy has been proposed as a generally useful chronometer for late Devonian time. Most of fifteen published MS stratigraphies crossing the Frasnian-Famennian boundary appear to share major excursions with the new McWhae Ridge result. Although upland tectonism in Canning Basin may be a caveat to straightforward eustatic interpretation of magnetic susceptibility variations, we suggest the higher-resolution and fresh drillcore context of this result prioritizes it as a standard for Frasnian-Famennian magnetic susceptibility variation.

  4. 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

  5. The elimination of magnetic susceptibility artifacts in the micro-image of liquid-solid interfaces: internal gradient modulation by the CPMG RF train.

    Science.gov (United States)

    Duh, Andrej; Mohoric, Ales; Stepisnik, Janez; Sersa, Igor

    2003-01-01

    Distortions of magnetic resonance images near solid-liquid interface appear as the result of the restriction to spin self-diffusion in the proximity of impermeable boundary as well as of a susceptibility difference. The spectral analysis of spin echo enables to resolve, in a simple way, how various RF-gradient pulse sequences reduce the effect of the internal magnetic field induced by the susceptibility difference at interfaces. The 1D diffusion-weighted imaging of water in the narrow notch tested efficiency of some sequence. The notch was milled in a piece of Plexiglas. The method can be used to distinguish the susceptibility effect from the effects of applied gradients when investigating the transport of fluid through a porous structure.

  6. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Heill, L.K.

    1995-05-01

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

  8. 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.

  9. A cluster-glass magnetic state in R5Pd2 (R = Ho, Tb) compounds evidenced by AC-susceptibility and neutron scattering measurements.

    Science.gov (United States)

    Gubkin, A F; Sherstobitova, E A; Terentyev, P B; Hoser, A; Baranov, N V

    2013-06-12

    AC- and DC-susceptibility, high-field magnetization and neutron diffraction measurements have been performed in order to study the magnetic state of R5Pd2 (R = Ho, Tb) compounds. The results show that both compounds undergo cluster-glass freezing upon cooling below Tf. According to the neutron diffraction a long-range magnetic order is absent down to 2 K and magnetic clusters with short-range incommensurate antiferromagnetic correlations exist not only below Tf but also in a wide temperature range above the freezing temperature (at least up to 2Tf). A complex cluster-glass magnetic state existing in Ho5Pd2 and Tb5Pd2 down to low temperatures results in rather complicated magnetization behavior in DC and AC magnetic fields. Such an unusual magnetic state in compounds with a high rare-earth concentration may be associated with the layered type of their crystal structure and with substantial atomic disorder, which results in frustrations in the magnetic subsystem.

  10. 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.

  11. Susceptibility to Hamstring Injuries in Soccer: A Prospective Study Using Muscle Functional Magnetic Resonance Imaging.

    Science.gov (United States)

    Schuermans, Joke; Van Tiggelen, Damien; Danneels, Lieven; Witvrouw, Erik

    2016-05-01

    Running-related hamstring strain injuries remain a delicate issue in several sports such as soccer. Their unremittingly high incidence and recurrence rates indicate that the underlying risk has not yet been fully identified. Among other factors, the importance of neuromuscular coordination and the quality of interplay between the different hamstring muscle bellies is thought to be a key determinant within the intrinsic injury risk. Muscle functional magnetic resonance imaging (mfMRI) is one of the tools that has been proven to be valid for evaluating intermuscular coordination. To investigate the risk of sustaining an index or recurring soccer-related hamstring injury by exploring metabolic muscle characteristics using mfMRI. Cohort study; Level of evidence, 2. A total of 27 healthy male soccer players and 27 soccer players with a history of hamstring injuries underwent standardized mfMRI. The mfMRI protocol consisted of a resting scan, a strenuous bilateral eccentric hamstring exercise, and a postexercise scan. The exercise-related T2 change, or the signal intensity shift between both scans, was used to detect differences in metabolic characteristics between (1) the different hamstring muscle bellies and (2) the prospective cohorts based on the (re)occurrence of hamstring injuries during a follow-up period of 18 months. The risk of sustaining a first hamstring injury was associated with alterations in the intermuscular hierarchy in terms of the magnitude of the metabolic response after a heavy eccentric effort, with the dominant role of the semitendinosus set aside for a higher contribution of the biceps femoris (P = .017). Receiver operating characteristic (ROC) curve analysis demonstrated that this variable was significantly able to predict the occurrence of index injuries with a sensitivity of 100% and a specificity of 70% when the metabolic activity of the biceps femoris exceeded 10%. The risk of sustaining a reinjury was associated with a substantial deficit

  12. 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

  13. Effect of mechanical milling on particle size, magnetic susceptibility and dielectric of synthetic toner colorant magnetite extracted from Indonesian iron sand

    Science.gov (United States)

    Zulaikah, S.; Mufti, N.; Fuad, A.; Dwi, L. D.

    2014-09-01

    As a colorant and additive substance for toner, magnetite (Fe3O4) has become main mineral that can produce electrical charge on printing process. In this research, we reports the effect of mechanical milling time to magnetic susceptibility, morphology and dielectric properties of synthetic toner The standard of the grain size of toner including of magnetite dissolved, are ranged from 2 to 10 micron or less, depending on the kind of toner. The results of this research show that the average of particle size decreases from 15μm to 5 μm by milling time between 6 hour to 9 hour and almost constant up to 12 hour. The magnetic susceptibility of the sample decreases as decreasing particle size, while the dielectric constant increases as decreasing particle size.

  14. 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

  15. 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 (waters (AAIW, UCDW), have uncovered new stratigraphic and paleoceanographic aspects of the Plio-Pleistocene in the South Atlantic. Based on strontium isotope analysis of well-preserved foraminifera-rich sediment a stratigraphy was developed from lowess curve fitting of the data and an 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.

  16. The IGCP Project 580 Application of magnetic susceptibility on Paleozoic sedimentary rocks has been launched: the project outlines, scope and the first results related to Central European region

    Czech Academy of Sciences Publication Activity Database

    Koptíková, Leona; Hladil, Jindřich; da Silva, A.C.; Whalen, M. T.; Boulvain, F.; Chen, D.; Spassov, S.; Devleeschouwer, X.

    2009-01-01

    Roč. 79, - (2009), s. 25-27 ISSN 1017-8880. [Regional Devonian Workshop Prague & Graz. 25.05.2009-27.05.2009, Prague] Grant - others: UNESCO -IUGS IGCP 580 Institutional research plan: CEZ:AV0Z30130516 Keywords : magnetic susceptibility * paleo¨zoic * sedimentary rocks Subject RIV: DB - Geology ; Mineralogy http://www.geologie.ac.at/filestore/download/BR0079_025_A.pdf

  17. Time-Transgressive Nature of the Magnetic Susceptibility Record across the Chinese Loess Plateau at the Pleistocene/Holocene Transition.

    Directory of Open Access Journals (Sweden)

    Yajie Dong

    Full Text Available The loess stratigraphic boundary at the Pleistocene/Holocene transition defined by the magnetic susceptibility (MS has previously been assumed to be synchronous with the Marine Isotope Stage (MIS 2/1 boundary, and approximately time-synchronous at different sections across the Chinese Loess Plateau (CLP. However, although this assumption has been used as a basis for proxy-age model of Chinese loess deposits, it has rarely been tested by using absolute dating methods. In this study, we applied a single-aliquot regenerative-dose (SAR protocol to the 45-63 μm quartz grain-size fraction to derive luminescence ages for the last glacial and Holocene sections of three loess sections on a transect from southeast to northwest across the CLP. Based on the 33 closely spaced optically stimulated luminescence (OSL samples from the three sections, OSL chronologies were established using a polynomial curve fit at each section. Based on the OSL chronology, the timing of the Pleistocene/Holocene boundary, as defined by rapid changes in MS values, is dated at ~10.5 ka, 8.5 ka and 7.5 ka in the Yaoxian section, Jingchuan and Huanxian sections respectively. These results are clearly inconsistent with the MIS 2/1 boundary age of 12.05 ka, and therefore we conclude that the automatic correlation of the Pleistocene/Holocene transition, as inferred from the MS record, with the MIS 2/1 boundary is incorrect. The results clearly demonstrate that the marked changes in MS along the southeast to northwest transect are time-transgressive among the different sites, with the timing of significant paleosol development as indicated by the MS record being delayed by 3-4 ka in the northwest compared to the southeast. Our results suggest that this asynchronous paleosol development during the last deglacial was caused by the delayed arrival of the summer monsoon in the northwest CLP compared to the southeast.

  18. Electronic miniband structure, heat capacity and magnetic susceptibility of monolayer and bilayer silicene in TI, VSPM and BI regimes

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-04-11

    In the current work, we theoretically study the electronic band structure (EBS), electronic heat capacity (EHC) and magnetic susceptibility (MS) of three structures including monolayer, AA-stacked and AB-stacked bilayer silicene based on the Kane–Mele Hamiltonian model and Green's function method. The particular attention of this study is paid to the effect of external electric field on the aforementioned physical properties. By variation of the electric field, three phases are found: Topological insulator (TI), valley–spin polarized metal (VSPM) and band insulator (BI). Marvellously, its electronic minibands show that the spin-up contribution of charge carriers with lowest energy bands behaves like relativistic Dirac fermions with linear (parabolic) energy dispersions in monolayer (bilayer) case near the Dirac points. An insightful analysis shows that the maximum and minimum value of EHC peak appear for (AA) AB-stacked bilayer and monolayer silicene in TI (BI) regime while in MS curves appear for (AB) AA-stacked bilayer and monolayer lattices in TI (BI) regime, respectively. Moreover, we have observed a phase transition from antiferromagnetic to ferromagnetic and paramagnetic in the monolayer and bilayer structures in the VSPM regime based on the MS findings, respectively. - Highlights: • Comparison of electronic miniband structure of monolayer and bilayer silicene by using the Kane–Mele model and Green's function technique. • Investigation and comparison the electronic contribution of heat capacity for different configurations of silicene structures. • Observation of phase transition from antiferromagnetic to ferromagnetic and paramagnetic phase in the monolayer and bilayer cases, respectively.

  19. Crystallography, magnetic susceptibility, heat capacity, and electrical resistivity of heavy-fermion LiV2O4 single crystals grown using a self-flux technique

    Science.gov (United States)

    Das, S.; Zong, X.; Niazi, A.; Ellern, A.; Yan, J. Q.; Johnston, D. C.

    2007-08-01

    Magnetically pure spinel compound LiV2O4 is a rare d -electron heavy fermion. Measurements on single crystals are needed to clarify the mechanism for the heavy-fermion behavior in the pure material. In addition, it is known that small concentrations (<1mol%) of magnetic defects in the structure strongly affect the properties, and measurements on single crystals containing magnetic defects would help to understand the latter behaviors. Herein, we report flux growth of LiV2O4 and preliminary measurements to help resolve these questions. The magnetic susceptibility of some as-grown crystals show a Curie-like upturn at low temperatures, showing the presence of magnetic defects within the spinel structure. The magnetic defects could be removed in some of the crystals by annealing them at 700°C . A very high specific heat coefficient γ=450mJ/molK2 was obtained at a temperature of 1.8K for a crystal containing a magnetic defect concentration ndefect=0.5mol% . A crystal with ndefect=0.01mol% showed a residual resistivity ratio of 50.

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

    Science.gov (United States)

    Gautam, Pitambar; Blaha, Ulrich; Appel, Erwin

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

  1. 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

  2. High Magnetic Susceptibility in a Highly Saline Sulfate-Rich Aquifer Undergoing Biodegradation of Hydrocarbon Results from Sulfate Reduction.

    Science.gov (United States)

    Atekwana, E. A.; Enright, A.; Ntarlagiannis, D.; Slater, L. D.; Bernier, R.; Beaver, C. L.; Rossbach, S.

    2016-12-01

    We investigated the chemical and stable carbon isotope composition of groundwater in a highly saline aquifer contaminated with hydrocarbon. Our aim to evaluate hydrocarbon degradation and to constrain the geochemical conditions that generated high anomalous magnetic susceptibility (MS) signatures observed at the water table interface. The occurrence of high MS in the water table fluctuating zone has been attributed to microbial iron reduction, suggesting the use of MS as a proxy for iron cycling. The highly saline aquifer had total dissolved solids concentrations of 3.7 to 29.3 g/L and sulfate concentrations of 787 to 37,100 mg/L. We compared our results for groundwater locations with high hydrocarbon contamination (total petroleum hydrocarbon (TPH) >10 mg/L), at lightly contaminated (TPH TEAs) dissolved oxygen (DO), nitrate (NO3-), dissolved iron (Fe2+) , dissolved manganese (Mn2+), sulfate (SO42-) and methane (CH4) suggest a chemically heterogeneous aquifer, probably controlled by heterogeneous distribution of TEAs and contamination (type of hydrocarbon, phase and age of contamination). The concentrations of dissolved inorganic carbon (DIC) ranged from 67 to 648 mg C/L and the stable carbon isotope (δ13CDIC) ranged from -30.0‰ to 1.0 ‰ and DIC-δ13CDIC modeling indicates that the carbon in the DIC is derived primarily from hydrocarbon degradation. The concentrations of Fe2+ in the aquifer ranged from 0.1 to 55.8 mg/L, but was mostly low, averaging 2.7+10.9 mg/L. Given the low Fe2+ [AE1] in the aqueous phase and the high MS at contaminated locations, we suggest that the high MS observed does not arise from iron reduction but rather from sulfate reduction. Sulfate reduction produces H2S which reacts with Fe2+ to produce ferrous sulfide (Fe2+S) or the mixed valence greigite (Fe2+Fe3+2S4). We conclude that in highly saline aquifers with high concentrations of sulfate and contaminated with hydrocarbon, dominance of sulfate reduction as the TEA is responsible for

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

    Czech Academy of Sciences Publication Activity Database

    Grison, Hana; Petrovský, Eduard; Kapička, Aleš; Hanzlíková, Hana

    2017-01-01

    Roč. 209, č. 2 (2017), s. 654-660 ISSN 0956-540X R&D Projects: GA ČR GA13-10775S; GA MŠk(CZ) LG15036 Institutional support: RVO:67985530 Keywords : magnetic properties * environmental magnetism * rock and mineral magnetism Subject RIV: DE - Earth Magnetism, Geodesy, Geography OBOR OECD: Physical geography Impact factor: 2.414, year: 2016

  4. Magnetic susceptibility measurements in Yellowstone National Park, USA; Beikoku Yellowstone kokuritsu koen ni okeru genchi jikaritsu sokutei

    Energy Technology Data Exchange (ETDEWEB)

    Okuma, S. [Geological Survey of Japan, Tsukuba (Japan)

    1997-05-27

    For the purpose of interpreting data of the aeromagnetic anomalies in Yellowstone National Park in the U.S.A., in-situ magnetization intensity measurements have been carried out in 1994 and 1995 on geological outcrops of rocks in that area. Comparisons and discussions were given on the measurement results, and existing rock magnetic data and aeromagnetic anomaly data available for the area. Outside the Yellowstone caldera, part of granitic gneisses among the Precambrian granitic gneisses and crystalline schists distributed to the north has an abnormally high magnetization intensity of 1 {times} 10 {sup -2} SI. This could be a powerful anomaly source for the high magnetic anomaly in this area. Paleogene volcanic rocks distributed widely in the eastern part of the park also have magnetization intensity as high as 1 {times} 10 {sup -2} SI or higher, which are also thought a powerful anomaly source in this area. Part of Pleistocene basalts which are exposed partially in the western part of the park has also very high magnetization intensity at 1 {times} 10 {sup -2} SI or higher. This suggests correlation with the magnetic anomaly in the east-west direction distributed in this area. Quaternary rhyolites are more magnetic than Quaternary welded tuffs, which should give greater effects to the magnetic anomaly. 10 refs., 5 figs.

  5. Magnetic field dependence of the magnetic susceptibility and the specific heat of the doped plasticized polyaniline (PANI-DB3EPSA){sub 0.5}

    Energy Technology Data Exchange (ETDEWEB)

    Djurado, D; Pron, A; Jacquot, J F; Travers, J P [Structure et Proprietes d' Architectures Moleculaires UMR5819 (CEA-CNRS-UJF), INAC/SPrAM and INAC/SCIB, CEA Grenoble, 17 rue des Martyrs, 38054-Grenoble-cedex9 (France); Adriano, C; Vargas, J M; Pagliuso, P G; Rettori, C [Instituto de Fisica ' Gleb Wataghin' , UNICAMP, CEP 13083-970, Campinas, SP (Brazil); Lesseux, G G; Fier, I; Walmsley, L, E-mail: walmsley@rc.unesp.br [Departamento de Fisica, Instituto de Geociencias e Ciencias Exatas, Universidade Estadual Paulista, Caixa Postal 178, CEP 13500-970, Rio Claro, Sao Paulo (Brazil)

    2011-05-25

    Specific heat, magnetization and electron spin resonance (ESR) data obtained from a self-standing film of the doped plasticized polyaniline (PANI-DB3EPSA){sub 0.5} are shown. No long range magnetic order has been observed at zero magnetic field, above 2 K. For a magnetic field of 3.3 kOe applied perpendicular to the plane of the film, a clear signature of an induced ordered state can be seen in the specific heat data and ESR also reveals this antiferromagnetic order. An electronic contribution is detected from ESR, magnetization and specific heat; however, for T {<=} 5 K, the specific heat data show the existence of a gap. Magnetization data also show a low temperature dominant Curie behaviour which cannot be seen from ESR, probably due to a very large linewidth, suggesting short range correlations among spin 1/2 polarons.

  6. 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.

  7. 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.

  8. Application of magnetic susceptibility as a paleoclimatic proxy on Paleozoic sedimentary rocks and characterization of the magnetic signal – IGCP-580 projects and event

    Czech Academy of Sciences Publication Activity Database

    da Silva, A-Ch.; Whalen, M. T.; Hladil, Jindřich; Koptíková, Leona; Chen, D.; Spassov, S.; Boulvain, F.; Devleeschouwer, X.

    2014-01-01

    Roč. 37, č. 2 (2014), s. 87-95 ISSN 0705-3797 Institutional support: RVO:67985831 Keywords : rock magnetism * high-resolution stratigraphy * palaeoclimatic archives * computing * Paleozoic * Phanerozoic * Recent Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 2.000, year: 2014 http://www.episodes.co.in/contents/2014/june/pp87-95.pdf

  9. 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

  10. Padé approximations for the magnetic susceptibilities of Heisenberg antiferromagnetic spin chains for various spin values

    International Nuclear Information System (INIS)

    Law, J M; Benner, H; Kremer, R K

    2013-01-01

    The temperature dependence of the spin susceptibilities of S = 1, 3/2 , 2, 5/2 and 7/2 Heisenberg antiferromagnetic 1D spins chains with nearest-neighbor coupling was simulated via quantum Monte Carlo calculations, within the reduced temperature range of 0.005 ≤ T* ≤ 100, and fitted to a Padé approximation with deviations between the simulated and fitted data of the same order of magnitude as or smaller than the quantum Monte Carlo simulation error. To demonstrate the practicality of our theoretical findings, we compare these results with the susceptibility of the well known 1D chain compound TMMC ([(CH 3 ) 4 N[MnCl 3

  11. MR imaging differentiation of Fe{sup 2+} and Fe{sup 3+} based on relaxation and magnetic susceptibility properties

    Energy Technology Data Exchange (ETDEWEB)

    Dietrich, Olaf [Ludwig-Maximilians-University Hospital Munich, Josef Lissner Laboratory for Biomedical Imaging, Institute for Clinical Radiology, Munich (Germany); Levin, Johannes [Ludwig-Maximilians-University Hospital Munich, Department of Neurology, Munich (Germany); German Center for Neurodegenerative Diseases (DZNE), Munich (Germany); Ahmadi, Seyed-Ahmad; Plate, Annika; Boetzel, Kai [Ludwig-Maximilians-University Hospital Munich, Department of Neurology, Munich (Germany); Reiser, Maximilian F.; Ertl-Wagner, Birgit [Ludwig-Maximilians-University Hospital Munich, Institute for Clinical Radiology, Munich (Germany); Giese, Armin [Ludwig-Maximilians-University Munich, Center for Neuropathology and Prion Research, Munich (Germany)

    2017-04-15

    The aim of this study is to evaluate the MR imaging behavior of ferrous (Fe{sup 2+}) and ferric (Fe{sup 3+}) iron ions in order to develop a noninvasive technique to quantitatively differentiate between both forms of iron. MRI was performed at 3 T in a phantom consisting of 21 samples with different concentrations of ferrous and ferric chloride solutions (between 0 and 10 mmol/L). A multi-echo spoiled gradient-echo pulse sequence with eight echoes was used for both T{sub 2}* and quantitative susceptibility measurements. The transverse relaxation rate, R{sub 2}* = 1/T{sub 2}*, was determined by nonlinear exponential fitting based on the mean signals in each sample. The susceptibilities, χ, of the samples were calculated after phase unwrapping and background field removal by fitting the spatial convolution of a unit dipole response to the measured internal field map. Relaxation rate changes, ΔR{sub 2}*(c{sub Fe}), and susceptibility changes, Δχ(c{sub Fe}), their linear slopes, as well as the ratios ΔR{sub 2}*(c{sub Fe}) / Δχ(c{sub Fe}) were determined for all concentrations. The linear slopes of the relaxation rate were (12.5 ± 0.4) s{sup -1}/(mmol/L) for Fe{sup 3+} and (0.77 ± 0.09) s{sup -1}/(mmol/L) for Fe{sup 2+} (significantly different, z test P < 0.0001). The linear slopes of the susceptibility were (0.088 ± 0.003) ppm/(mmol/L) for Fe{sup 3+} and (0.079 ± 0.006) ppm/(mmol/L) for Fe{sup 2+}. The individual ratios ΔR{sub 2}*/Δχ were greater than 40 s{sup -1}/ppm for all samples with ferric solution and lower than 20 s{sup -1}/ppm for all but one of the samples with ferrous solution. Ferrous and ferric iron ions show significantly different relaxation behaviors in MRI but similar susceptibility patterns. These properties can be used to differentiate ferrous and ferric samples. (orig.)

  12. 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

    Cyclostratigraphic calibration of magnetic susceptibility data along with stable isotopic and geochemical proxy data for redox, productivity, and detrital input from western Canada provide insight into the pace and timing of the Late Devonian, Frasnian-Famennian (F-F) biotic crisis. Two organic-rich shales that, in much of the world, display geochemical anomalies indicating low oxygen conditions and carbon burial characterize the F-F event. These events, referred to as the Lower and Upper Kellwasser events (LKE & UKE), have been linked to the evolutionary expansion of deeply rooted terrestrial forests and the concomitant changes in soil development and chemical weathering and changes in Late Devonian climate. Our geochemical data record relatively high levels of redox sensitive trace metals (Mo, U, V), proxies for biological productivity (Ba, Cu, Ni, Zn), and detrital input (Al, Si, Ti, Zr) during both events. C stable isotopic data generated from organic matter records a 3-4‰ positive excursion during both events. Each event is recorded in lowstand and/or early transgressive facies. These data corroborate hypotheses about enhanced biological productivity, driven by heightened terrestrial detrital input, leading to low oxygen conditions and decreases in biotic diversity during during relatively low stands of Late Devonian sea level. Age dating of such events in deep time is problematic due to insufficient biochronologic control. Each event is within one conodont biostratigraphic zone, with durations on the order of 0.5-1.0 Ma. Time series analysis of high-resolution magnetic susceptibility data identified 16 long eccentricity cycles (405 ky) during the Frasnian stage and one in the earliest Famennian stage. The geochemical anomalies associated with the LKE and UKE are recorded over 7 and 14 m of stratigraphic section respectively. These strata represent only a portion of a 405 ky long eccentricity cycle and astronomical tuning implies that the LKE likely occurred

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

    DEFF Research Database (Denmark)

    Fock, Jeppe; Parmvi, Mattias; Strömberg, Mattias

    2017-01-01

    -out frequency, when detecting the signal due to MNP agglomerates (turn-on detection strategy). These observations are considered to be caused by differences in the volumedependence of the magnetic and optical signals from agglomerates. The highest signal from agglomerates was found in the optomagnetic signal...

  14. Magnetic susceptibility of (IPA) 2FeCl 4, (IBuA) 2FeCl 4 and (IPA) 2CuCi 4 (IPA = isopropylammonium ion and IBuA = isobutylammonium ion)

    Science.gov (United States)

    Ahmed, M. A.; Mousa, M. A.

    1989-08-01

    The magnetic susceptibility of (IPA) 2FeCl 4, (IBuA) 2FeCl 4 and (IPA) 2CuCl 4, where IPA = (CH 3) 2CHNH +3 and IBuA = (CH 3) 2CHCH 2NH +3, were measured in the temperature range form 80 K up to a temperature near the melting points of the samples. The results obtained were interpreted in termw of a canted two-dimensional antiferromagnet. The variation of the magnetic susceptibility with the change in the composition was also discussed.

  15. Magnetic susceptibility and heat capacity of V2O3 and V1.973Me0.020O3 (Me = Fe, Cr, and Al)

    Science.gov (United States)

    Lyakh, O. V.; Surikov, Vad. I.; Surikov, V. I.; Prokudina, N. A.

    2012-06-01

    The vanadium sesquioxide is chosen as an object of research. The metal-insulator phase transition accompanied by structural and antiferromagnetic transformations is observed in it when the temperature increases in the vicinity of Т Md ~ 170 K. It is well known that the temperature of the vanadium oxide phase transition depends not only on the sample structure within the homogeneity region, but also on the preparation doping by atoms of other type. Dependences of heat capacity С p and magnetic susceptibility χ on the temperature (80-300 K) are investigated for V2O3 and V1.973Me0.020O3 (Me = Fe, Cr, and Al) samples.

  16. Single-crystal growth, crystallography, magnetic susceptibility, heat capacity, and thermal expansion of the antiferromagnetic S=1 chain compound CaV[subscript 2]O[subscript 4

    Energy Technology Data Exchange (ETDEWEB)

    Niazi, A.; Bud' ko, S.L.; Schlagel, D.L.; Yan, J.Q.; Lograsso, T.A.; Kreyssig, A.; Das, S.; Nandi, S.; Goldman, A.I.; Honecker, A.; McCallum, R.W.; Reehuis, M.; Pieper, O.; Lake, B.; Johnston, D.C.; (Ames; Gö); (tingen); (HMI); (MXPL-F)

    2009-05-01

    The compound CaV{sub 2}O{sub 4} contains V{sup +3} cations with spin S=1 and has an orthorhombic structure at room temperature containing zigzag chains of V atoms running along the c axis. We have grown single crystals of CaV{sub 2}O{sub 4} and report crystallography, static magnetization, magnetic susceptibility x, ac magnetic susceptibility, heat capacity C{sub p}, and thermal expansion measurements in the temperature T range of 1.8--350 K on the single crystals and on polycrystalline samples. An orthorhombic-to-monoclinic structural distortion and a long-range antiferromagnetic (AF) transition were found at sample-dependent temperatures T{sub S}{approx}108--145 K and T{sub N}{approx}51--76 K, respectively. In two annealed single crystals, another transition was found at {approx}200 K. In one of the crystals, this transition is mostly due to V{sub 2}O{sub 3} impurity phase that grows coherently in the crystals during annealing. However, in the other crystal the origin of this transition at 200 K is unknown. The x(T) shows a broad maximum at {approx}300 K associated with short-range AF ordering and the anisotropy of x above T{sub N} is small. The anisotropic x(T{yields}0) data below T{sub N} show that the (average) easy axis of the AF magnetic structure is the b axis. The C{sub p}(T) data indicate strong short-range AF ordering above T{sub N}, consistent with the x(T) data. We fitted our x data by a J{sub 1}-J{sub 2} S=1 Heisenberg chain model, where J{sub 1}(J{sub 2}) is the (next)-nearest-neighbor exchange interaction. We find J{sub 1}{approx}230 K and surprisingly, J{sub 2}/J{sub 1}{approx}0 (or J{sub 1}/J{sub 2}{approx}0). The interaction J{sub {perpendicular}} between these S=1 chains leading to long-range AF ordering at T{sub N} is estimated to be J{sub {perpendicular}}/J{sub 1}{approx_equal}0.04.

  17. Signatures of a hybridization gap in magnetic susceptibility of Ce{sub 1-x}La{sub x}Os{sub 4}Sb{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Andraka, B; Ross, A [Department of Physics, University of Florida, PO Box 118440, Gainesville, FL 32611-8440 (United States); Rotundu, C R, E-mail: andraka@phys.ufl.edu [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2011-10-12

    The magnetic susceptibility of Ce{sub 1-x}La{sub x}Os{sub 4}Sb{sub 12}, with x approx. 0.2, exhibits a pronounced maximum at T{sub m} = 80 K. This T{sub m} coincides roughly with the temperature below which a small gap, believed to be a hybridization gap, is observed in spectroscopic measurements in undoped CeOs{sub 4}Sb{sub 12}. However, a similar anomaly, at a lower temperature of 50 K, is observed in LaOs{sub 4}Sb{sub 12}. Furthermore, there is a monotonic variation of T{sub m} with x, for x > 0.2, suggesting the same origin of the two anomalies and undermining a simple hybridization gap interpretation of the susceptibility of Ce{sub 1-x}La{sub x}Os{sub 4}Sb{sub 12} alloys, with x < 1. A possibility of the hybridization gap opening, induced by freezing out of local phonons, strongly coupled with electronic degrees of freedom, is discussed. (paper)

  18. Anisotropic Magnetic Susceptibility of Fault Rocks From Death Valley, CA: Comparison With Shape Preferred Orientation, and Implications for Kinematic Models of Brittle Foliation Development.

    Science.gov (United States)

    Hayman, N. W.; Housen, B.; Cladouhos, T.

    2002-12-01

    Anisotropic Magnetic Susceptibility (AMS) was measured for 11 samples of gouge and breccia from detachment faults that bound the Black Mts, Death Valley, CA. We reason that the AMS ellipsoid roughly describes the bulk deformational fabric within the 1.4 freely rotated (e.g. Jeffrey's-model behavior) within a general flow and upon reaching a critical orientation became insensitive to continuing strain. The inclination of the minimum principal susceptibility of the AMS ellipsoids is, for more than half of the samples, normal to the SPO and thus the fabric that is tracked by the SPO is also present in the matrix. This scale independence is described by the March model wherein the inclination of the foliation is proportional to the finite shear strain. In this model, the inclined foliation in the fault rocks developed with shear strains ca 4, and much of the >3.5 km of slip on the detachment accrued in gouges with a shear-zone parallel foliation or on localized slip surfaces. However, the AMS ellipsoids are not simply tracking one foliation within the X-Z plane and there is other evidence that the fault rocks developed through a protracted history of distributed deformation. A kinematic model involving more complex general flow thus may be more appropriate for describing the kinematic evolution of the fault zone.

  19. Relationships between magnetic susceptibility of limestones and sea level change ("direct relationship and major crises on the Earth")

    Czech Academy of Sciences Publication Activity Database

    Hladil, Jindřich; Slavík, Ladislav; Koptíková, Leona; Schnabl, Petr; Vacek, F.; Bábek, O.; Geršl, M.

    2008-01-01

    Roč. 34, 4/6 (2008), s. 1343596-1343596 ISSN 0161-6951. [International Geological Congress /33./. 06.08.2008-14.08.2008, Oslo ] R&D Projects: GA AV ČR IAA300130702; GA AV ČR(CZ) KJB300130613; GA AV ČR KJB307020602 Institutional research plan: CEZ:AV0Z30130516 Keywords : magnetic suceptibility * limestone * impurity * ocean-atmosperic circulation * past global crises Subject RIV: DB - Geology ; Mineralogy

  20. 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

  1. 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)

  2. Anisotropy of magnetic susceptibility as a tool for recognizing core deformation: reevaluation of the paleomagnetic record of Pleistocene sediments from drill hole OL-92, Owens Lake, California

    Science.gov (United States)

    Rosenbaum, Joseph; Reynolds, Richard T.; Smoot, Joseph; Meyer, Robert

    2000-01-01

    At Owens Lake, California, paleomagnetic data document the Matuyama/Brunhes polarity boundary near the bottom of a 323-m core (OL-92) and display numerous directional fluctuations throughout the Brunhes chron. Many of the intervals of high directional dispersion were previously interpreted to record magnetic excursions. For the upper ~120 m, these interpretations were tested using the anisotropy of magnetic susceptibility (AMS), which typically defines a subhorizontal planar fabric for sediments deposited in quiet water. AMS data from intervals of deformed core, determined from detailed analysis of sedimentary structures, were compared to a reference AMS fabric derived from undisturbed sediment. This comparison shows that changes in the AMS fabric provide a means of screening core samples for deformation and the associated paleomagnetic record for the adverse effects of distortion. For that portion of core OL-92 studied here (about the upper 120 m), the combined analyses of sedimentary structures and AMS data demonstrate that most of the paleomagnetic features, previously interpreted as geomagnetic excursions, are likely the result of core deformation.

  3. 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.

  4. 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

  5. Magnetic order and electronic properties of Li{sub 2}Mn{sub 2}(MoO{sub 4}){sub 3} material for lithium-ion batteries: ESR and magnetic susceptibility studies

    Energy Technology Data Exchange (ETDEWEB)

    Suleimanov, N.M. [E. K. Zavoisky Physical-Technical Institute of Russian Academy of Sciences, Kazan (Russian Federation); Kazan State Power Engineering University, Kazan (Russian Federation); Prabaharan, S.R.S. [VIT University, School of Electronics Engineering, Chennai (India); Khantimerov, S.M.; Nizamov, F.A. [E. K. Zavoisky Physical-Technical Institute of Russian Academy of Sciences, Kazan (Russian Federation); Michael, M.S. [SSN College of Engineering, Department of Chemistry, Chennai (India); Drulis, H.; Wisniewski, P. [Institute of Low Temperature and Structure Research of Polish Academy of Sciences, Wroclaw (Poland)

    2016-08-15

    We describe the application of electron spin resonance (ESR) and magnetic susceptibility methods to study the magnetic properties and valence state of transition metal ions in Li{sub 2}Mn{sub 2}(MoO4){sub 3} polyanion compound previously studied for its cathode-active properties in lithium containing batteries. ESR measurements of Li{sub 2}Mn{sub 2}(MoO{sub 4}){sub 3} have shown the presence of Mn{sup 2+} ions in the octahedral environment of oxygen ions. It is found that the part of manganese ions occupy the anti-site positions in lithium sublattice. The absence of the ESR signal from molybdenum ions indicates that they are non-magnetic and adopt the 6{sup +} valence state. Considerable overlapping between 3d orbitals of transition metal and 2p oxygen orbitals has been experimentally established. This leads to the indirect exchange interaction and antiferromagnetic ordering of manganese ions at 1.4 K. (orig.)

  6. Magnetic susceptibility evolution and sedimentary environments on carbonate platform sediments and atolls, comparison of the Frasnian from Belgium and Alberta, Canada

    Science.gov (United States)

    da Silva, Anne-Christine; Potma, Ken; Weissenberger, John A. W.; Whalen, Michael T.; Humblet, Marc; Mabille, Cédric; Boulvain, Frédéric

    2009-02-01

    Magnetic susceptibility (MS) measurements on carbonate rocks are considered as a proxy for impurities delivered to the carbonate environments. In the absence of strong climatic or tectonic variations, bulk MS values have been linked to sea level variations, because sea-level fall increases clastic supply and therefore increases in magnetic mineral deposition. In this paper we explore the relationship between the average magnitude of bulk MS, with shallowing-up sequences and facies evolution in different Devonian carbonate complexes. Similarities and differences between these parameters have been scrutinized in carbonate attached platform and detached platforms (mounds and/or atolls) from Belgium and Canada. In the carbonate attached platforms from Belgium and Canada, the MS patterns are directly related to depositional environment. Mean MS values increase from the most distal towards the most proximal facies and towards the top of the majority of fourth-order shallowing-up sequences. These trends are in agreement with theoretical background (MS increases with regression). In the Belgian detached platform, the average MS pattern generally shows an opposite behaviour to that observed in the attached carbonate platforms. Average MS decreases towards the most proximal facies and towards the top of a majority of the fourth-order shallowing-up sequences. This behaviour can be explained by the influence of sedimentary rate and water agitation during deposition. A high sedimentary rate will dilute the magnetic minerals in the atoll facies and the high water agitation during deposition may be expected to have prevented the deposition of the magnetic grains. So, the combination of these two effects will result in the observed low values in the atoll crown and lagoonal facies. In the Canadian detached platform, MS is mainly negative. This means that the limestones are very pure. The technique does not appear to be appropriate in these rocks. The variations of average MS

  7. 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

  8. Dynamic Susceptibility Contrast Perfusion Magnetic Resonance Imaging Demonstrates Reduced Periventricular Cerebral Blood Flow in Dogs with Ventriculomegaly

    Directory of Open Access Journals (Sweden)

    Martin J. Schmidt

    2017-08-01

    Full Text Available The nature of ventriculomegaly in dogs is still a matter of debate. Signs of increased intraventricular pressure and atrophy of the cerebral white matter have been found in dogs with ventriculomegaly, which would imply increased intraventricular pressure and, therefore, a pathological condition, i.e., to some extent. Reduced periventricular blood flow was found in people with high elevated intraventricular pressure. The aim of this study was to compare periventricular brain perfusion in dogs with and without ventriculomegaly using perfusion weighted-magnetic-resonance-imaging to clarify as to whether ventriculomegaly might be associated with an increase in intraventricular pressure. Perfusion was measured in 32 Cavalier King Charles spaniels (CKCS with ventriculomegaly, 10 CKCSs were examined as a control group. Cerebral blood flow (CBF was measured using free-hand regions of interest (ROI in five brain regions: periventricular white matter, caudate nucleus, parietal cortex, hippocampus, and thalamus. CBF was significantly lower in the periventricular white matter of the dogs with ventriculomegaly (p = 0.0029 but not in the other ROIs. Reduction of periventricular CBF might imply increase of intraventricular pressure in ventriculomegaly.

  9. Paramagnetic Meissner effect analyzed by second harmonics of the magnetic susceptibility: Consistency with a ground state carrying spontaneous currents

    International Nuclear Information System (INIS)

    Heinzel, C.; Theilig, T.; Ziemann, P.

    1993-01-01

    It has been reported recently by Braunisch et al. [Phys. Rev. Lett. 68, 1908 (1992)] that some ceramic high-T c superconductors (HTSC's) exhibit a paramagnetic signal if cooled through the superconducting transition temperature in small external magnetic dc fields (H dc 2 Sr 2 CaCu 2 O 8-x samples, some of which did not exhibit the PME. Thus, a comparison was possible between samples with and without the PME, subjected to different field-cooling procedures. The experimental results are consistent with the occurrence of a reversible transition into a PME state carrying spontaneous orbital currents resulting in corresponding paramagnetic moments, which can be reversibly aligned by small external dc fields. This PME state is attributed to loops containing relatively strong weak links, which are able to remain superconducting close to the bulk T c of the grains (e.g., at T/T c =0.9) and in external dc fields of at least 30 Oe

  10. 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.

  11. Voxel-Based Correlation between Coregistered Single-Photon Emission Computed Tomography and Dynamic Susceptibility Contrast Magnetic Resonance Imaging in Subjects with Suspected Alzheimer Disease

    International Nuclear Information System (INIS)

    Cavallin, L.; Axelsson, R.; Wahlund, L.O.; Oeksengard, A.R.; Svensson, L.; Juhlin, P.; Wiberg, M. Kristoffersen; Frank, A.

    2008-01-01

    Background: Current diagnosis of Alzheimer disease is made by clinical, neuropsychologic, and neuroimaging assessments. Neuroimaging techniques such as magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT) could be valuable in the differential diagnosis of Alzheimer disease, as well as in assessing prognosis. Purpose: To compare SPECT and 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 disease (AD). Material and Methods: 24 patients, eight with AD, 10 with MCI, and six controls, were investigated with SPECT using 99m Tc-hexamethylpropyleneamine oxime (HMPAO, Ceretec; GE Healthcare Ltd., Little Chalsont UK) and dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) with a contrast-enhancing gadobutrol formula (Gadovist; Bayer Schering Pharma, Berlin, Germany). Voxel-based correlation between coregistered SPECT and DSC-MR images was calculated. Region-of-interest (ROI) analyses were then performed in 24 different brain areas using brain registration and analysis of SPECT studies (BRASS; Nuclear Diagnostics AB, Stockholm (SE)) on both SPECT and DSC-MRI. Results: Voxel-based correlation between coregistered SPECT and DSC-MR showed a high correlation, with a mean correlation coefficient of 0.94. ROI analyses of 24 regions showed significant differences between the control group and AD patients in 10 regions using SPECT and five regions in DSC-MR. Conclusion: SPECT remains superior to DSC-MRI in differentiating normal from pathological perfusion, and DSC-MRI could not replace SPECT in the diagnosis of patients with Alzheimer disease

  12. Magnets

    International Nuclear Information System (INIS)

    Young, I.R.

    1984-01-01

    A magnet pole piece for an NMR imaging magnet is made of a plurality of magnetic wires with one end of each wire held in a non-magnetic spacer, the other ends of the wires being brought to a pinch, and connected to a magnetic core. The wires may be embedded in a synthetic resin and the magnetisation and uniformity thereof can be varied by adjusting the density of the wires at the spacer which forms the pole piece. (author)

  13. Impact of an iron mine and a nickel smelter at the Norwegian/Russian border close to the Barents Sea on surface soil magnetic susceptibility and content of potentially toxic elements.

    Science.gov (United States)

    Magiera, Tadeusz; Zawadzki, Jarosław; Szuszkiewicz, Marcin; Fabijańczyk, Piotr; Steinnes, Eiliv; Fabian, Karl; Miszczak, Ewa

    2018-03-01

    An important problem in soil magnetometry is unraveling the soil contamination signal in areas with multiple emitters. Here, geophysical and geochemical measurements were performed at four sites on a north - south transect along the Pasvik River in the Barents Region (northern Norway). These sites are influenced by depositions from the Bjørnevatn iron mine and a Ni-Cu smelter in Nikel, Russia. To relate the degree and type of pollution from these sources to the corresponding magnetic signal, the topsoil concentrations of 12 Potentially Toxic Elements (PTEs) (As, Cd, Co, Cr, Cu, Fe, Mo, Ni, Pb, Se, Ti, Zn), were determined, magnetic hysteresis parameters and thermomagnetic properties were measured. In situ magnetic low-field susceptibility decreases from north to south with increasing distance from the iron mine. Relatively large magnetic multidomain grains of magnetite and/or titanomagnetite are responsible for the strong magnetic signal from the topsoil close to Bjørnevatn. These particles are related to increased enrichment factors of As, Mo and Cu, yielding high positive correlation coefficients with susceptibility values. At a site furthest away from the iron mine and located 7 km from the Ni-Cu smelter magnetic susceptibility values are much lower but significant positive correlations on the level of p < .1 with 8 PTEs (Ni, Cu, Co, Se, As, Zn, Cd, Cr) have been observed. The magnetic signal in this area is due to fine-grained primary sulphides and secondary fine-grained magnetite and/or maghemite. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Autoregressive moving average (ARMA) model applied to quantification of cerebral blood flow using dynamic susceptibility contrast-enhanced magnetic resonance imaging

    International Nuclear Information System (INIS)

    Murase, Kenya; Yamazaki, Youichi; Shinohara, Masaaki

    2003-01-01

    The purpose of this study was to investigate the feasibility of the autoregressive moving average (ARMA) model for quantification of cerebral blood flow (CBF) with dynamic susceptibility contrast-enhanced magnetic resonance imaging (DSC-MRI) in comparison with deconvolution analysis based on singular value decomposition (DA-SVD). Using computer simulations, we generated a time-dependent concentration of the contrast agent in the volume of interest (VOI) from the arterial input function (AIF) modeled as a gamma-variate function under various CBFs, cerebral blood volumes and signal-to-noise ratios (SNRs) for three different types of residue function (exponential, triangular, and box-shaped). We also considered the effects of delay and dispersion in AIF. The ARMA model and DA-SVD were used to estimate CBF values from the simulated concentration-time curves in the VOI and AIFs, and the estimated values were compared with the assumed values. We found that the CBF value estimated by the ARMA model was more sensitive to the SNR and the delay in AIF than that obtained by DA-SVD. Although the ARMA model considerably overestimated CBF at low SNRs, it estimated the CBF more accurately than did DA-SVD at high SNRs for the exponential or triangular residue function. We believe this study will contribute to an understanding of the usefulness and limitations of the ARMA model when applied to quantification of CBF with DSC-MRI. (author)

  15. 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.

  16. Is the Susceptibility Vessel Sign on 3-Tesla Magnetic Resonance T2*-Weighted Imaging a Useful Tool to Predict Recanalization in Intravenous Tissue Plasminogen Activator?

    Science.gov (United States)

    Yamamoto, N; Satomi, J; Harada, M; Izumi, Y; Nagahiro, S; Kaji, R

    2016-09-01

    The aim of this study was to investigate the independent factors associated with the absence of recanalization approximately 24 h after intravenous administration of tissue-type plasminogen activator (IV TPA). The previous studies have been conducted using 1.5-Tesla (T) magnetic resonance imaging (MRI). We studied whether the characteristics of 3-T MRI findings were useful to predict outcome and recanalization after IV tPA. Patients with internal carotid artery (ICA) or middle cerebral artery (MCA) (horizontal portion, M1; Sylvian portion, M2) occlusion and treated by IV tPA were enrolled. We studied whether the presence of susceptibility vessel sign (SVS) at M1 and low clot burden score on T2*-weighted imaging (T2*-CBS) on 3-T MRI were associated with the absence of recanalization. A total of 49 patients were enrolled (27 men; mean age, 73.9 years). MR angiography obtained approximately 24 h after IV tPA revealed recanalization in 21 (42.9 %) patients. Independent factors associated with the absence of recanalization included ICA or proximal M1 occlusion (odds ratio, 69.6; 95 % confidence interval, 5.05-958.8, p = 0.002). In this study, an independent factor associated with the absence of recanalization may be proximal occlusion of the cerebral arteries rather than SVS in the MCA or low T2*-CBS on 3-T MRI.

  17. Superconductivity, magnetic susceptibility, and electronic properties of amorphous (Mo/sub 1-x/Ru/sub x/)80P20 alloys obtained by liquid quenching

    International Nuclear Information System (INIS)

    Johnson, W.L.; Poon, S.J.; Duwez, P.

    1977-11-01

    Results of x-ray diffraction, transmission electron diffraction, and crystallization studies on amorphous (Mo/sub 1-x/Ru/sub x/) 80 P 20 alloys obtained by liquid quenching are presented and discussed. The alloys are all found to be superconducting with transition temperatures ranging from approximately 3 0 K to approximately 9 0 K. The variation of T/sub c/ with alloy composition is compared to that obtained by Collver and Hammond for vapor quenched transition metal films. Results of magnetic susceptibility measurements are used to estimate the variation of the electronic density of states at the Fermi level, N(0), from the Pauli paramagnetic contribution. The relationship between the variation of T/sub c/ and N(0) is discussed in terms of the microscope theory of superconductivity. Finally, results of measurements of the upper critical field H/sub c2/, and the normal state electronic transport properties are presented and compared with recent theoretical models for amorphous superconductors

  18. Vertical-axis rotations and deformation along the active strike-slip El Tigre Fault (Precordillera of San Juan, Argentina) assessed through palaeomagnetism and anisotropy of magnetic susceptibility

    Science.gov (United States)

    Fazzito, Sabrina Y.; Rapalini, Augusto E.; Cortés, José M.; Terrizzano, Carla M.

    2017-03-01

    Palaeomagnetic data from poorly consolidated to non-consolidated late Cenozoic sediments along the central segment of the active El Tigre Fault (Central-Western Precordillera of the San Juan Province, Argentina) demonstrate broad cumulative deformation up to 450 m from the fault trace and reveal clockwise and anticlockwise vertical-axis rotations of variable magnitude. This deformation has affected in different amounts Miocene to late Pleistocene samples and indicates a complex kinematic pattern. Several inherited linear structures in the shear zone that are oblique to the El Tigre Fault may have acted as block boundary faults. Displacement along these faults may have resulted in a complex pattern of rotations. The maximum magnitude of rotation is a function of the age of the sediments sampled, with largest values corresponding to middle Miocene-lower Pliocene deposits and minimum values obtained from late Pleistocene deposits. The kinematic study is complemented by low-field anisotropy of magnetic susceptibility data to show that the local strain regime suggests a N-S stretching direction, subparallel to the strike of the main fault.

  19. Diagnostic performance of susceptibility-weighted magnetic resonance imaging for the assessment of sub-coracoacromial spurs causing subacromial impingement syndrome.

    Science.gov (United States)

    Nörenberg, Dominik; Armbruster, Marco; Bender, Yi-Na; Walter, Thula; Ebersberger, Hans U; Diederichs, Gerd; Hamm, Bernd; Ockert, Ben; Makowski, Marcus R

    2017-03-01

    To evaluate the potential of susceptibility-weighted-magnetic-resonance-imaging (SWMR) for the detection of sub-coracoacromial spurs in patients with clinically suspected subacromial impingement syndrome (SAIS), compared to standard MR-sequences and radiographs. Forty-four patients with suspected SAIS were included. All patients underwent radiography, standard MRI of the shoulder and SWMR. Radiograph-based identification of sub-coracoacromial spurs served as goldstandard. Radiographs identified twenty-three spurs in twenty-three patients. Twenty-one patients without spur formation served as reference group. Detection rate, sensitivity/specificity and interobserver-agreements were calculated. Linear regression was applied to determine the relationship between size measurements on radiographs and MRI. Detection rates for spurs on standard MRI and SWMR were 47.8 % and 91.3 % compared to radiography (pformation in patients with SAIS and is superior to standard MR-sequences using radiography as goldstandard. • SWMR has the potential to reliably identify sub-coracoacromial spurs without radiation exposure. • SWMR provides comparable detection rates to conventional radiography for sub-coracoacromial spur formation. • SWMR yields higher detection rates compared to standard-MR regarding sub-coracoacromial spur formation. • SWMR can be implemented in routine shoulder MRI protocols.

  20. Changes in susceptibility signs on serial T2*-weighted single-shot echo-planar gradient-echo images in acute embolic infarction: comparison with recanalization status on 3D time-of-flight magnetic resonance angiography

    International Nuclear Information System (INIS)

    Shinohara, Yuki; Kinoshita, Toshibumi; Kinoshita, Fumiko

    2012-01-01

    The present study compares changes in susceptibility signs on follow-up single-shot echo-planar gradient-echo T2*-weighted images (GRE-EPI) with vascular status on follow-up magnetic resonance angiography (MRA) in acute embolic infarction. Twenty consecutive patients with acute embolic infarction repeatedly underwent MR imaging including GRE-EPI and MRA using a 1.5-T MR superconducting system. All patients underwent initial MR examination within 24 h of onset and follow-up MR imaging within 1 month after onset. Changes in susceptibility signs on follow-up GRE-EPI were compatible with vascular status on follow-up MRA in 19 of the 20 patients. Susceptibility signs disappeared with complete recanalization in 13 patients, migrated with partial recanalization in 3, did not change together with the absence of recanalization in 2, and became extended together with the absence of recanalization in 1. Cerebral hemorrhage obscured susceptibility signs in the one remaining patient. Susceptibility signs on follow-up GRE-EPI can reflect changes in an acute embolus, such as recanalization or migration, in this study. Serial GRE-EPI in acute embolism complements the diagnostic certainty of MRA by directly detecting an embolus as a susceptibility sign. (orig.)

  1. Precise position of the Basal Choteč event and evolution of sedimentary environments near the Lower–Middle Devonian boundary: The magnetic susceptibility, gamma-ray spectrometric, lithological, and geochemical record of the Prague Synform (Czech Republic)

    Czech Academy of Sciences Publication Activity Database

    Koptíková, Leona

    2011-01-01

    Roč. 304, 1/2 (2011), s. 96-112 ISSN 0031-0182 R&D Projects: GA AV ČR KJB307020602; GA AV ČR IAAX00130702 Institutional research plan: CEZ:AV0Z30130516 Keywords : magnetic susceptibility * Gamma-ray spectrometry * Prague Synform * Lower–Middle Devonian Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.392, year: 2011

  2. Diagnostic performance of susceptibility-weighted magnetic resonance imaging for the assessment of sub-coracoacromial spurs causing subacromial impingement syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Noerenberg, Dominik; Armbruster, Marco [Munich University Hospitals Campus Grosshadern, Department of Clinical Radiology, Munich (Germany); Bender, Yi-Na; Walter, Thula; Diederichs, Gerd; Hamm, Bernd [Charite - University Medicine Berlin, Department of Radiology, Berlin (Germany); Ebersberger, Hans U. [Heart Center Munich-Bogenhausen, Department of Cardiology and Intensive Care Medicine, Munich (Germany); Ockert, Ben [Munich University Hospitals Campus Grosshadern, Department of Trauma and Orthopedic Surgery, Shoulder and Elbow Service, Munich (Germany); Makowski, Marcus R. [Charite - University Medicine Berlin, Department of Radiology, Berlin (Germany); King' s College London, Division of Imaging Sciences and Biomedical Engineering, London (United Kingdom)

    2017-03-15

    To evaluate the potential of susceptibility-weighted-magnetic-resonance-imaging (SWMR) for the detection of sub-coracoacromial spurs in patients with clinically suspected subacromial impingement syndrome (SAIS), compared to standard MR-sequences and radiographs. Forty-four patients with suspected SAIS were included. All patients underwent radiography, standard MRI of the shoulder and SWMR. Radiograph-based identification of sub-coracoacromial spurs served as goldstandard. Radiographs identified twenty-three spurs in twenty-three patients. Twenty-one patients without spur formation served as reference group. Detection rate, sensitivity/specificity and interobserver-agreements were calculated. Linear regression was applied to determine the relationship between size measurements on radiographs and MRI. Detection rates for spurs on standard MRI and SWMR were 47.8 % and 91.3 % compared to radiography (p<0.001). SWMR demonstrated a sensitivity of 97.7 % (CI=0.92-1) and a specificity of 91.3 % (CI=0.788-1) for the identification of spurs. Standard MR-sequences achieved a sensitivity of 47.8 % (CI=0.185-0.775) and a specificity of 80.8 % (CI=0.642-0.978). Size measurements between SWMR and radiography showed a good correlation (R{sup 2}=0.75;p<0.0001), while overestimating lesion size (5.7±1.2 mm; 4.3±1.3 mm;p<0.0001). Interobserver-agreement for spurs was high on SWMR (R{sup 2}=0.74;p<0.0001), but low on standard MRI (R{sup 2}=0.24;p<0.0001). SWMR allows a reliable detection of sub-coracoacromial spur formation in patients with SAIS and is superior to standard MR-sequences using radiography as goldstandard. (orig.)

  3. The Use of Portable X-ray Flourescence, Magnetic Susceptibility and Scanning Electron Microscope to Classify, characterize, and Determine Redox State of Granites

    Science.gov (United States)

    Abbott, J. R.; Fellows, S. A.

    2016-12-01

    Utah contains granitic intrusions associated with various ore deposits that vary spatially, temporally, and chemically. Utah is a great location to study mineralization associated with granites because it encompasses three unique geologic provinces and offers a wide array of emplacement configurations. Past studies in Utah have primarily focused on major elements and there is also a paucity of trace analyses and most studies are only on one discrete location. Trace element analysis can be used for classifying granites and also locating potential mineralized granites. Trace element analysis of granites may also lend insight into magma redox, which is important for ore formation. Trace element and redox analyses are both expensive and time consuming. We wanted to determine redox and trace element distribution using tools that are cost effective and readily available. Portable x-ray fluorescence (pXRF) offers an affordable solution to quickly acquire large counts for key trace elements in granites. These semi-quantitative results may also help determine redox. We present a technique to better determine the redox state of granitic rocks using pXRF and magnetic susceptibility a tool that is underutilized in the field. Additionally, we show that mineral mapping of oxides and sulfur-bearing minerals in thin section by SEM, aids in determining the redox state of granites by looking at Fe and Ti ratios and observing the presence of sulfate or sulfide. By utilizing equipment that is readily available and cost effective we are able to better understand the redox state, and mineralizing potential of various granites. This is important to workers interested in locating ore deposits or understanding the granitic system.

  4. Contribution of Anisotropy of Magnetic Susceptibility (AMS to reconstruct flooding characteristics of a 4220 BP tsunami from a thick unconsolidated structureless deposit (Banda Aceh, Sumatra

    Directory of Open Access Journals (Sweden)

    Patrick Christian Wassmer

    2015-07-01

    Full Text Available One of the main concerns of deciphering tsunami sedimentary records along seashore is to link the emplaced layers with marine high energy events. Based on a combination of morphologic features, sedimentary figures, grain size characteristics, fossils content, microfossils assemblages, geochemical elements, heavy minerals presence; it is, in principle, possible to relate the sedimentary record to a tsunami event. However, experience shows that sometimes, in reason of a lack of any visible sedimentary features, it is hard to decide between a storm and a tsunami origin. To solve this issue, the authors have used the Anisotropy of Magnetic Susceptibility (AMS to evidence the sediment fabric. The validity of the method for reconstructing flow direction has been proved when applied on sediments in the aftermath of a tsunami event, for which the behaviour was well documented (2004 IOT. We present herein an application of this method for a 56 cm thick paleo-deposit dated 4220 BP laying under the soil covered by the 2004 IOT, SE of Banda Aceh, North Sumatra. We analysed this homogenous deposit, lacking of any visible structure, using methods of classic sedimentology to confirm the occurrence of a high energy event. We then applied AMS technique that allowed the reconstruction of flow characteristics during sediment emplacement. We show that all the sequence was emplaced by uprush phases and that the local topography played a role on the re-orientation of a part of the uprush flow, creating strong reverse current. This particular behaviour was reported by eyewitnesses during the 2004 IOT event.

  5. Diagnostic performance of susceptibility-weighted magnetic resonance imaging for the assessment of sub-coracoacromial spurs causing subacromial impingement syndrome

    International Nuclear Information System (INIS)

    Noerenberg, Dominik; Armbruster, Marco; Bender, Yi-Na; Walter, Thula; Diederichs, Gerd; Hamm, Bernd; Ebersberger, Hans U.; Ockert, Ben; Makowski, Marcus R.

    2017-01-01

    To evaluate the potential of susceptibility-weighted-magnetic-resonance-imaging (SWMR) for the detection of sub-coracoacromial spurs in patients with clinically suspected subacromial impingement syndrome (SAIS), compared to standard MR-sequences and radiographs. Forty-four patients with suspected SAIS were included. All patients underwent radiography, standard MRI of the shoulder and SWMR. Radiograph-based identification of sub-coracoacromial spurs served as goldstandard. Radiographs identified twenty-three spurs in twenty-three patients. Twenty-one patients without spur formation served as reference group. Detection rate, sensitivity/specificity and interobserver-agreements were calculated. Linear regression was applied to determine the relationship between size measurements on radiographs and MRI. Detection rates for spurs on standard MRI and SWMR were 47.8 % and 91.3 % compared to radiography (p<0.001). SWMR demonstrated a sensitivity of 97.7 % (CI=0.92-1) and a specificity of 91.3 % (CI=0.788-1) for the identification of spurs. Standard MR-sequences achieved a sensitivity of 47.8 % (CI=0.185-0.775) and a specificity of 80.8 % (CI=0.642-0.978). Size measurements between SWMR and radiography showed a good correlation (R 2 =0.75;p<0.0001), while overestimating lesion size (5.7±1.2 mm; 4.3±1.3 mm;p<0.0001). Interobserver-agreement for spurs was high on SWMR (R 2 =0.74;p<0.0001), but low on standard MRI (R 2 =0.24;p<0.0001). SWMR allows a reliable detection of sub-coracoacromial spur formation in patients with SAIS and is superior to standard MR-sequences using radiography as goldstandard. (orig.)

  6. Assessment of climatic and seismic cycles in southern chile from high resolution XRF and magnetic susceptibility measurements of historic lake sediments.

    Science.gov (United States)

    Boes, X.; Hubert-Ferrari, A.; Fagel, N.

    2006-12-01

    The high-resolution sedimentological studies performed on the sediment cores collected in the oceans or in the lakes constitutes the basis for inter-comparison of past climate variability. Among the new high-resolution approaches, the X-Ray Fluorescence (XRF) analysis of varved marine and lacustrine cores represents some of the best resolution. These data are particularly useful for tracking short-term climate changes expressed with calibrated time scales. However, the XRF results obtain on the fresh cores surface may be of low resolution because the core material is wet and unconsolidated. One particularly attractive method to solve this problem consists of impregnating the sediment cores with polymers in order to polish the core surface for XRF analyses. This step is essential for being able to get significant XRF and Magnetic Susceptibility (MS) results in the muddy cores. Since the 1960s, the evolution of sediment impregnation methods has been strongly linked to the development of innovative techniques (e.g., sampling devices, cryogenic and vacuum technologies, polymers, etc.). In this communication, we first propose a revised method that may be applied to prepare sediment cores for high-resolution XRF and MS data acquisition. Then we show an example of XRF and MS results obtain on laminated lake sediments from South America (Lago Puyehue, 40°S). As this area is very sensitive in terms of precipitation change (i.e., Southern Westerlies); the XRF data are compared with the regional instrumental precipitation database. The results are discussed in terms of climate and sismo- tectonic impacts over historic times. Our results shows that, in order to better interpret XRF tool over long sequences, the measurements should be first "calibrated" according to instrumental data such as precipitation, temperatures, and earthquake magnitudes.

  7. Attempts to Improve Absolute Quantification of Cerebral Blood Flow in Dynamic Susceptibility Contrast Magnetic Resonance Imaging: A Simplified T1-Weighted Steady-State Cerebral Blood Volume Approach

    International Nuclear Information System (INIS)

    Wirestam, R.; Knutsson, L.; Risberg, J.; Boerjesson, S.; Larsson, E.M.; Gustafson, L.; Passant, U.; Staahlberg, F.

    2007-01-01

    Background: Attempts to retrieve absolute values of cerebral blood flow (CBF) by dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) have typically resulted in overestimations. Purpose: To improve DSC-MRI CBF estimates by calibrating the DSC-MRI-based cerebral blood volume (CBV) with a corresponding T1-weighted (T1W) steady-state (ss) CBV estimate. Material and Methods: 17 volunteers were investigated by DSC-MRI and 133Xe SPECT. Steady-state CBV calculation, assuming no water exchange, was accomplished using signal values from blood and tissue, before and after contrast agent, obtained by T1W spin-echo imaging. Using steady-state and DSC-MRI CBV estimates, a calibration factor K = CBV(ss)/CBV(DSC) was obtained for each individual. Average whole-brain CBF(DSC) was calculated, and the corrected MRI-based CBF estimate was given by CBF(ss) = KxCBF(DSC). Results: Average whole-brain SPECT CBF was 40.1±6.9 ml/min 100 g, while the corresponding uncorrected DSC-MRI-based value was 69.2±13.8 ml/mi 100 g. After correction with the calibration factor, a CBF(ss) of 42.7±14.0 ml/min 100 g was obtained. The linear fit to CBF(ss)-versus-CBF(SPECT) data was close to proportionality (R 0.52). Conclusion: Calibration by steady-state CBV reduced the population average CBF to a reasonable level, and a modest linear correlation with the reference 133Xe SPECT technique was observed. Possible explanations for the limited accuracy are, for example, large-vessel partial-volume effects, low post-contrast signal enhancement in T1W images, and water-exchange effects

  8. Late Eocene-Oligocene history of tectonic strain on the NE Tibetan plateau inferred from the anisotropy of magnetic susceptibility of the fluvio-lacustrine sediments in the Lanzhou Basin

    Science.gov (United States)

    Zhang, Peng; Ao, Hong

    2017-04-01

    The anisotropy of magnetic susceptibility (AMS) is sensitive to tectonic strain, which has been widely used to investigate the structural geology. Here we present rock magnetism results from the Lanzhou Basin in NE Tibetan plateau, to discuss the relationship between the tectonic strain recorded in the foreland basin and mountain building. The χ-T curves and IRM component analysis indicate the presence of both magnetite and hematite in the fluvio-lacustrine sediments in the Lanzhou Basin. Hematite is the main magnetic mineral dominating the AMS fabric. The AMS fabric indicates a W-E direction strain, in agreement with the current movement direction of the Lanzhou Basin in global positioning system (GPS) measurements. The significant changes in distribution of kmin and shape parameter T at ca 30 Ma may imply increasing tectonic strain related to the mountain building of the NE Tibetan Plateau, in line with the evidence from the Qaidam basin.

  9. MAGNET

    CERN Multimedia

    by B. Curé

    2011-01-01

    The magnet operation was very satisfactory till the technical stop at the end of the year 2010. The field was ramped down on 5th December 2010, following the successful regeneration test of the turbine filters at full field on 3rd December 2010. This will limit in the future the quantity of magnet cycles, as it is no longer necessary to ramp down the magnet for this type of intervention. This is made possible by the use of the spare liquid Helium volume to cool the magnet while turbines 1 and 2 are stopped, leaving only the third turbine in operation. This obviously requires full availability of the operators to supervise the operation, as it is not automated. The cryogenics was stopped on 6th December 2010 and the magnet was left without cooling until 18th January 2011, when the cryoplant operation resumed. The magnet temperature reached 93 K. The maintenance of the vacuum pumping was done immediately after the magnet stop, when the magnet was still at very low temperature. Only the vacuum pumping of the ma...

  10. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      Following the unexpected magnet stops last August due to sequences of unfortunate events on the services and cryogenics [see CMS internal report], a few more events and initiatives again disrupted the magnet operation. All the magnet parameters stayed at their nominal values during this period without any fault or alarm on the magnet control and safety systems. The magnet was stopped for the September technical stop to allow interventions in the experimental cavern on the detector services. On 1 October, to prepare the transfer of the liquid nitrogen tank on its new location, several control cables had to be removed. One cable was cut mistakenly, causing a digital input card to switch off, resulting in a cold-box (CB) stop. This tank is used for the pre-cooling of the magnet from room temperature down to 80 K, and for this reason it is controlled through the cryogenics control system. Since the connection of the CB was only allowed for a field below 2 T to avoid the risk of triggering a fast d...

  11. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      The magnet was energised at the beginning of March 2012 at a low current to check all the MSS safety chains. Then the magnet was ramped up to 3.8 T on 6 March 2012. Unfortunately two days later an unintentional switch OFF of the power converter caused a slow dump. This was due to a misunderstanding of the CCC (CERN Control Centre) concerning the procedure to apply for the CMS converter control according to the beam-mode status at that time. Following this event, the third one since 2009, a discussion was initiated to define possible improvement, not only on software and procedures in the CCC, but also to evaluate the possibility to upgrade the CMS hardware to prevent such discharge from occurring because of incorrect procedure implementations. The magnet operation itself was smooth, and no power cuts took place. As a result, the number of magnetic cycles was reduced to the minimum, with only two full magnetic cycles from 0 T to 3.8 T. Nevertheless the magnet suffered four stops of the cryogeni...

  12. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    Operation of the magnet has gone quite smoothly during the first half of this year. The magnet has been at 4.5K for the full period since January. There was an unplanned short stop due to the CERN-wide power outage on May 28th, which caused a slow dump of the magnet. Since this occurred just before a planned technical stop of the LHC, during which access in the experimental cavern was authorized, it was decided to leave the magnet OFF until 2nd June, when magnet was ramped up again to 3.8T. The magnet system experienced a fault also resulting in a slow dump on April 14th. This was triggered by a thermostat on a filter choke in the 20kA DC power converter. The threshold of this thermostat is 65°C. However, no variation in the water-cooling flow rate or temperature was observed. Vibration may have been the root cause of the fault. All the thermostats have been checked, together with the cables, connectors and the read out card. The tightening of the inductance fixations has also been checked. More tem...

  13. 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

  14. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

      The magnet was operated without any problem until the end of the LHC run in February 2013, apart from a CERN-wide power glitch on 10 January 2013 that affected the CMS refrigerator, causing a ramp down to 2 T in order to reconnect the coldbox. Another CERN-wide power glitch on 15 January 2013 didn’t affect the magnet subsystems, the cryoplant or the power converter. At the end of the magnet run, the reconnection of the coldbox at 2.5 T was tested. The process will be updated, in particular the parameters of some PID valve controllers. The helium flow of the current leads was reduced but only for a few seconds. The exercise will be repeated with the revised parameters to validate the automatic reconnection process of the coldbox. During LS1, the water-cooling services will be reduced and many interventions are planned on the electrical services. Therefore, the magnet cryogenics and subsystems will be stopped for several months, and the magnet cannot be kept cold. In order to avoid unc...

  15. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    The magnet was successfully operated at the end of the year 2009 despite some technical problems on the cryogenics. The magnet was ramped up to 3.8 T at the end of November until December 16th when the shutdown started. The magnet operation met a few unexpected stops. The field was reduced to 3.5 T for about 5 hours on December 3rd due to a faulty pressure sensor on the helium compressor. The following day the CERN CCC stopped unintentionally the power converters of the LHC and the experiments, triggering a ramp down that was stopped at 2.7 T. The magnet was back at 3.8 T about 6 hours after CCC sent the CERN-wide command. Three days later, a slow dump was triggered due to a stop of the pump feeding the power converter water-cooling circuit, during an intervention on the water-cooling plant done after several disturbances on the electrical distribution network. The magnet was back at 3.8 T in the evening the same day. On December 10th a break occurred in one turbine of the cold box producing the liquid ...

  16. MAGNET

    CERN Multimedia

    B. Curé

    2011-01-01

    The CMS magnet has been running steadily and smoothly since the summer, with no detected flaw. The magnet instrumentation is entirely operational and all the parameters are at their nominal values. Three power cuts on the electrical network affected the magnet run in the past five months, with no impact on the data-taking as the accelerator was also affected at the same time. On 22nd June, a thunderstorm caused a power glitch on the service electrical network. The primary water cooling at Point 5 was stopped. Despite a quick restart of the water cooling, the inlet temperature of the demineralised water on the busbar cooling circuit increased by 5 °C, up to 23.3 °C. It was kept below the threshold of 27 °C by switching off other cooling circuits to avoid the trigger of a slow dump of the magnet. The cold box of the cryogenics also stopped. Part of the spare liquid helium volume was used to maintain the cooling of the magnet at 4.5 K. The operators of the cryogenics quickly restarted ...

  17. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      The magnet and its sub-systems were stopped at the beginning of the winter shutdown on 8th December 2011. The magnet was left without cooling during the cryogenics maintenance until 17th January 2012, when the cryoplant operation resumed. The magnet temperature reached 93 K. The vacuum pumping was maintained during this period. During this shutdown, the yearly maintenance was performed on the cryogenics, the vacuum pumps, the magnet control and safety systems, and the power converter and discharge lines. Several preventive actions led to the replacement of the electrovalve command coils, and the 20A DC power supplies of the magnet control system. The filters were cleaned on the demineralised water circuits. The oil of the diffusion pumps was changed. On the cryogenics, warm nitrogen at 343 K was circulated in the cold box to regenerate the filters and the heat exchangers. The coalescing filters have been replaced at the inlet of both the turbines and the lubricant trapping unit. The active cha...

  18. Fine-grained non-carbonate particles embedded in neritic to pelagic limestones (Lochkovian to Emsian, Prague synform, Czech Republic): composition, provenance and links to magnetic susceptibility and gamma-ray logs

    Czech Academy of Sciences Publication Activity Database

    Koptíková, Leona; Hladil, Jindřich; Slavík, Ladislav; Čejchan, Petr; Bábek, O.

    2010-01-01

    Roč. 13, č. 4 (2010), s. 407-430 ISSN 1374-8505 R&D Projects: GA AV ČR IAA300130702; GA ČR GAP210/10/2351 Institutional research plan: CEZ:AV0Z30130516 Keywords : non-carbonate impurities * limestones * magnetic susceptibility * gamma-ray spectrometry * REE distributions * atmospheric dust * Lower Devonian * Prague Synform Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.645, year: 2010 http://popups.ulg.ac.be/Geol/docannexe.php?id=3123

  19. Kinetic analysis of superparamagnetic iron oxide nanoparticles in the liver of body-temperature-controlled mice using dynamic susceptibility contrast magnetic resonance imaging and an empirical mathematical model.

    Science.gov (United States)

    Murase, Kenya; Assanai, Purapan; Takata, Hiroshige; Matsumoto, Nozomi; Saito, Shigeyoshi; Nishiura, Motoko

    2015-06-01

    The purpose of this study was to develop a method for analyzing the kinetic behavior of superparamagnetic iron oxide nanoparticles (SPIONs) in the murine liver under control of body temperature using dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) and an empirical mathematical model (EMM). First, we investigated the influence of body temperature on the kinetic behavior of SPIONs in the liver by controlling body temperature using our temperature-control system. Second, we investigated the kinetic behavior of SPIONs in the liver when mice were injected with various doses of GdCl3, while keeping the body temperature at 36°C. Finally, we investigated it when mice were injected with various doses of zymosan, while keeping the body temperature at 36°C. We also investigated the effect of these substances on the number of Kupffer cells by immunohistochemical analysis using the specific surface antigen of Kupffer cells (CD68). To quantify the kinetic behavior of SPIONs in the liver, we calculated the upper limit of the relative enhancement (A), the rates of early contrast uptake (α) and washout or late contrast uptake (β), the parameter related to the slope of early uptake (q), the area under the curve (AUC), the maximum change of transverse relaxation rate (ΔR2) (ΔR2(max)), the time to ΔR2(max) (Tmax), and ΔR2 at the last time point (ΔR2(last)) from the time courses of ΔR2 using the EMM. The β and Tmax values significantly decreased and increased, respectively, with decreasing body temperature, suggesting that the phagocytic activity of Kupffer cells is significantly affected by body temperature. The AUC, ΔR2(max), and ΔR2(last) values decreased significantly with increasing dose of GdCl3, which was consistent with the change in the number of CD68-positive cells. They increased with increasing dose of zymosan, which was also consistent with the change in the number of CD68-positive cells. These results suggest that AUC, ΔR2(max), and ΔR2

  20. MAGNET

    CERN Multimedia

    B. Curé

    2011-01-01

    The magnet ran smoothly in the last few months until a fast dump occurred on 9th May 2011. Fortunately, this occurred in the afternoon of the first day of the technical stop. The fast dump was due to a valve position controller that caused the sudden closure of a valve. This valve is used to regulate the helium flow on one of the two current leads, which electrically connects the coil at 4.5 K to the busbars at room temperature. With no helium flow on the lead, the voltage drop and the temperatures across the leads increase up to the defined thresholds, triggering a fast dump through the Magnet Safety System (MSS). The automatic reaction triggered by the MSS worked properly. The helium release was limited as the pressure rise was just at the limit of the safety valve opening pressure. The average temperature of the magnet reached 72 K. It took four days to recover the temperature and refill the helium volumes. The faulty valve controller was replaced by a spare one before the magnet ramp-up resumed....

  1. A new tool for in situ measurements of the vertical distribution of magnetic susceptibility in soils as basis for mapping deposited dust

    Czech Academy of Sciences Publication Activity Database

    Petrovský, Eduard; Hůlka, Z.; Kapička, Aleš

    2004-01-01

    Roč. 25, č. 9 (2004), s. 1021-1029 ISSN 0959-3330 R&D Projects: GA AV ČR KSK3046108 Keywords : environmental magnetism * soil contamination * anthropogenic magnetite Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.507, year: 2004

  2. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    The magnet worked very well at 3.8 T as expected, despite a technical issue that manifested twice in the cryogenics since June. All the other magnet sub-systems worked without flaw. The issue in the cryogenics was with the cold box: it could be observed that the cold box was getting progressively blocked, due to some residual humidity and air accumulating in the first thermal exchanger and in the adsorber at 65 K. This was later confirmed by the analysis during the regeneration phases. An increase in the temperature difference between the helium inlet and outlet across the heat exchanger and a pressure drop increase on the filter of the adsorber were observed. The consequence was a reduction of the helium flow, first compensated by the automatic opening of the regulation valves. But once they were fully opened, the flow and refrigeration power reduced as a consequence. In such a situation, the liquid helium level in the helium Dewar decreased, eventually causing a ramp down of the magnet current and a field...

  3. MAGNET

    CERN Multimedia

    B. Curé

    MAGNET During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bough...

  4. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

    The magnet is fully stopped and at room temperature. The maintenance works and consolidation activities on the magnet sub-systems are progressing. To consolidate the cryogenic installation, two redundant helium compressors will be installed as ‘hot spares’, to avoid the risk of a magnet downtime in case of a major failure of a compressor unit during operation. The screw compressors, their motors, the mechanical couplings and the concrete blocks are already available and stored at P5. The metallic structure used to access the existing compressors in SH5 will be modified to allow the installation of the two redundant ones. The plan is to finish the installation and commissioning of the hot spare compressors before the summer 2014. In the meantime, a bypass on the high-pressure helium piping will be installed for the connection of a helium drier unit later during the Long Shutdown 1, keeping this installation out of the schedule critical path. A proposal is now being prepared for the con...

  5. MAGNET

    CERN Multimedia

    Benoit Curé.

    The magnet operation restarted end of June this year. Quick routine checks of the magnet sub-systems were performed at low current before starting the ramps up to higher field. It appeared clearly that the end of the field ramp down to zero was too long to be compatible with the detector commissioning and operations plans. It was decided to perform an upgrade to keep the ramp down from 3.8T to zero within 4 hours. On July 10th, when a field of 1.5T was reached, small movements were observed in the forward region support table and it was decided to fix this problem before going to higher field. At the end of July the ramps could be resumed. On July 28th, the field was at 3.8T and the summer CRAFT exercise could start. This run in August went smoothly until a general CERN wide power cut took place on August 3rd, due to an insulation fault on the high voltage network outside point 5. It affected the magnet powering electrical circuit, as it caused the opening of the main circuit breakers, resulting in a fast du...

  6. Emplacement of Zebín Hill, Jičín Volcanic Field, Bohemian Paradise, Czech Republic: Anisotropy of Magnetic Susceptibility, Ground Magnetometry, Electric Resistivity Tomography, and Paleomagnetic Data

    Science.gov (United States)

    Petronis, M. S.; Rapprich, , V.; Valenta, J.; Leman, J.; Brister, A. R.; van Wyk de Vries, B.

    2014-12-01

    A well-preserved set of mid-Miocene tuff-cones and their feeders outcrop in the Jičín Volcanic Field, Czech Republic. Zebín Hill is a tuff cone that has been quarried to reveal the volcanoes feeder system. This edifice offers the opportunity to understand how magma is transported through a monogenetic pyroclastic cone. Rock types include a coarse-grained basal phreatomagmatic layer and a stratified upper wall facies both of which are penetrated by feeder dikes. Anisotropy of magnetic susceptibility (AMS) and paleomagnetic data were collected at twenty-one sites from feeder dikes and the main conduit of the volcano. A high-resolution ground magnetometry survey, electric resistivity tomography and seismic tomography were also conducted. Magnetic susceptibility intensity indicates that the dominant magnetic mineral is a ferromagnetic phase with little contribution from paramagnetic minerals. AMS ellipsoids shapes are both oblate and prolate and inferred magma flow directions indicate magma flow away from the central vent area and subhorizontal flow towards and away from the axial conduit; both upward and downward magma flow is evident at some sites. Curie point estimates yield a spectrum of results indicating a mixture of high-Ti titanomagnetite, iron sulfide, and low-Ti titanomagnetite. Ground magnetometry data indicate that both normal and reverse polarity rocks are present at Zebín Hill. Paleomagnetic data confirm the ground magnetic data in that both normal and reverse polarity rocks are present. Most sites yield a single component magnetization that is well grouped at the site level and carried by pseudosingle domain titanomagnetite. The presence of both normal and reverse polarity magnetizations from the volcano indicate that significant time passed during the growth of this monogenic system. Complex system of branching dikes has been also observed from electric resistivity tomography. The simple external structure of monogenetic volcanoes hides a rather

  7. Structural stability and electronic behaviors of Co1-xOsxSi and macroscopic magnetic susceptibilities of CoSi and OsSi: GGA-PBEsol, GW-approximation and QTAIM investigations

    Science.gov (United States)

    Bouafia, H.; Sahli, B.; Timaoui, M. A.; Djebour, B.; Hiadsi, S.; Abidri, B.

    2018-02-01

    The present work represents a theoretical investigation based on FP-(L)APW + lo method of structural properties, mechanical stability and electronic properties of Co1-xOsxSi as well as the macroscopic magnetic susceptibilities of CoSi and OsSi. The structural properties such as cell parameter, bulk modulus, internal parameters and total energy of non-magnetic NM, ferromagnetic FM and antiferromagnetic AFM phases were predicted by GGA-PBEsol semilocal functional. The obtained results for CoSi and OsSi are in good agreement with those found previously. The spin, orbital and total macroscopic magnetic susceptibilities of CoSi and OsSi have been estimated and confirmed that these compounds are diamagnetic. The total energy of the ferromagnetic phase of Co1-xOsxSi (with x = 0.25, 0.5 and 0.75) is the lowest indicating that they are ferromagnetic materials. The generalized stability criteria indicate that Co1-xOsxSi maintain their mechanical stabilities under a hydrostatic pressure less than 10 GPa. The electronic properties calculated by GW-approximation indicate that CoSi and Co1-xOsxSi (with x = 0.25, 0.50 and 0.75) are semimetals whereas OsSi is a semiconductor with a pseudo-direct band-gap. The topological analysis by QTAIM and the charge density plots indicate that the strong covalent character is predominant for Cosbnd Si, Ossbnd Si and Cosbnd Os bonds.

  8. Experiments on Magnetic Materials

    Science.gov (United States)

    Schneider, C. S.; Ertel, John P.

    1978-01-01

    Describes the construction and use of a simple apparatus to measure the magnetization density and magnetic susceptibility of ferromagnetic, paramagnetic, and the diamagnetic solids and liquids. (Author/GA)

  9. MAGNET

    CERN Multimedia

    Benoit Curé

    The magnet subsystems resumed operation early this spring. The vacuum pumping was restarted mid March, and the cryogenic power plant was restarted on March 30th. Three and a half weeks later, the magnet was at 4.5 K. The vacuum pumping system is performing well. One of the newly installed vacuum gauges had to be replaced at the end of the cool-down phase, as the values indicated were not coherent with the other pressure measurements. The correction had to be implemented quickly to be sure no helium leak could be at the origin of this anomaly. The pressure measurements have been stable and coherent since the change. The cryogenics worked well, and the cool-down went quite smoothly, without any particular difficulty. The automated start of the turbines had to be fine-tuned to get a smooth transition, as it was observed that the cooling power delivered by the turbines was slightly higher than needed, causing the cold box to stop automatically. This had no consequence as the cold box safety system acts to keep ...

  10. MAGNET

    CERN Multimedia

    B. Curé

    During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bought. Th...

  11. 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

  12. MAGNET

    CERN Multimedia

    B. Curé

    The first phase of the commissioning ended in August by a triggered fast dump at 3T. All parameters were nominal, and the temperature recovery down to 4.5K was carried out in two days by the cryogenics. In September, series of ramps were achieved up to 3 and finally 3.8T, while checking thoroughly the detectors in the forward region, measuring any movement of and around the HF. After the incident of the LHC accelerator on September 19th, corrective actions could be undertaken in the forward region. When all these displacements were fully characterized and repetitive, with no sign of increments in displacement at each field ramp, it was possible to start the CRAFT, Cosmic Run at Four Tesla (which was in fact at 3.8T). The magnet was ramped up to 18.16kA and the 3 week run went smoothly, with only 4 interruptions: due to the VIP visits on 21st October during the LHC inauguration day; a water leak on the cooling demineralized water circuit, about 1 l/min, that triggered a stop of the cooling pumps, and resulte...

  13. MAGNET

    CERN Multimedia

    Benoit Curé

    The cooling down to the nominal temperature of 4.5 K was achieved at the beginning of August, in conjunction with the completion of the installation work of the connection between the power lines and the coil current leads. The temperature gradient on the first exchanger of the cold box is now kept within the nominal range. A leak of lubricant on a gasket of the helium compressor station installed at the surface was observed and several corrective actions were necessary to bring the situation back to normal. The compressor had to be refilled with lubricant and a regeneration of the filters and adsorbers was necessary. The coil cool down was resumed successfully, and the cryogenics is running since then with all parameters being nominal. Preliminary tests of the 20kA coil power supply were done earlier at full current through the discharge lines into the dump resistors, and with the powering busbars from USC5 to UXC5 without the magnet connected. On Monday evening August 25th, at 8pm, the final commissionin...

  14. MAGNET

    CERN Multimedia

    Benoit Curé

    2013-01-01

    Maintenance work and consolidation activities on the magnet cryogenics and its power distribution are progressing according to the schedules. The manufacturing of the two new helium compressor frame units has started. The frame units support the valves, all the sensors and the compressors with their motors. This activity is subcontracted. The final installation and the commissioning at CERN are scheduled for March–April 2014. The overhauls of existing cryogenics equipment (compressors, motors) are in progress. The reassembly of the components shall start in early 2014. The helium drier, to be installed on the high-pressure helium piping, has been ordered and will be delivered in the first trimester of 2014. The power distribution for the helium compressors in SH5 on the 3.3kV network is progressing. The 3.3kV switches, between each compressor and its hot spare compressor, are being installed, together with the power cables for the new compressors. The 3.3kV electrical switchboards in SE5 will ...

  15. Magnetic susceptibility of solid solutions Bi2SrNb2-2xFe2xO9-δ

    Science.gov (United States)

    Zhuk, N. A.; Chezhina, N. V.; Belyy, V. A.; Makeev, B. A.; Yermolina, M. V.; Miroshnichenko, A. S.

    2018-04-01

    The state of iron atoms and their interatomic interactions were investigated by the method of magnetic dilution in Bi2SrNb2-2xFe2xO9-δ with a layered perovskite-like structure. It was found that the solid solutions are characterized by increased values of the magnetic moment of iron atoms, compared with purely spin values of Fe(III). This was explained by the presence of exchange-bound aggregates of Fe(III) atoms with antiferro- and ferromagnetic types of exchange. The dependencies of the exchange parameters and cluster distribution on the iron content of Bi2SrNb2-2xFe2xO9-δ solid solutions were calculated.

  16. Thermal transport properties, magnetic susceptibility and neutron diffraction studies of the (Cr100-xAlx)95Mo5 alloy system

    Science.gov (United States)

    Muchono, B.; Sheppard, C. J.; Venter, A. M.; Prinsloo, A. R. E.

    2018-05-01

    The Seebeck coefficient has been used to investigate QCB in Cr alloys [8,9]. Plots of d S /d T (in the limit T → 2 K) as function of concentration for the (Cr97.8Si2.2)100-yMoy [8] and the (Cr84Re16)100-zVz [9] alloy systems depicted anomalies at the QCP. The possibility of QCB in the (Cr100-xAlx)95Mo5 alloy system is explored by analysing the S(T) data of Fig. 1 by performing a linear-least-squares fit through the 2 K < T < 6.5 K data points. The gradient was taken as dS / dT|T → 2K . Fig. 8 shows dS / dT|T → 2K for concentrations in the range 0.5 ≤ x ≤ 8.6. It increases rapidly to a maximum at x = 1.0, then decreases on further Al addition and displays a minimum just above x = 1.4. This is the concentration where magnetism is seen to disappear on the TN(x) magnetic phase diagram. dS / dT|T → 2K shows a second minimum just above x = 4.4, i.e. corresponding to the concentration where magnetism reappears on the TN(x) magnetic phase diagram (see Fig. 17). Similar minima were also observed at the QCP in the (Cr84Re16)100-zVz [9] and (Cr86Ru14)100-rVr [13] alloy systems. The relatively large error bars in Fig. 8 originate from the large errors in the fitting routine due to a significant scatter in the original Seebeck coefficient data at low temperatures. The solid line through the dS / dT|T → 2K data points is a guide to the eye, while the dotted vertical lines indicate the boundaries between the ISDW, P and CSDW phases. The minima observed in the dS / dT|T → 2K curve correlate to these boundaries.

  17. Synthetic antiferromagnetic nanoparticles with tunable susceptibilities

    Science.gov (United States)

    Hu, Wei; Wilson, Robert J.; Earhart, Christopher M.; Koh, Ai Leen; Sinclair, Robert; Wang, Shan X.

    2009-01-01

    High-moment monodisperse disk-shaped Co–Fe magnetic nanoparticles, stable in aqueous solution, were physically fabricated by using nanoimprinted templates and vacuum deposition techniques. These multilayer synthetic antiferromagnetic nanoparticles exhibit nearly zero magnetic remanence and coercivity, and susceptibilities which can be tuned by exploiting interlayer magnetic interactions. In addition, a low cost method of scaling up the production of sub-100 nm synthetic antiferromagnetic nanoparticles is demonstrated. PMID:19529797

  18. Suscetibilidade magnética do horizonte B de solos do Estado do Paraná Magnetic susceptibility of B horizon of soils in the State of Paraná

    Directory of Open Access Journals (Sweden)

    Alceu Rodrigues da Silva

    2010-04-01

    Full Text Available Os minerais ferrimagnéticos maghemita (γFe2O3 e magnetita (Fe3O4 possuem alta relação com a disponibilidade de cátions metálicos e com a capacidade do solo em adsorver ânions como o fosfato. Uma percentagem expressiva dos solos brasileiros apresenta magnetização espontânea. No Estado do Paraná essa área corresponde a aproximadamente 50 %. A determinação da suscetibilidade magnética por unidade de massa (ΧBF é o método mais simples de identificar a presença e quantificar esses minerais nos solos. A BF é uma técnica rápida, barata, não destrutiva e de boa reprodutibilidade, que pode ser utilizada como critério nos estudos pedogenéticos em que os minerais ferrimagnéticos estão presentes. O objetivo deste trabalho foi verificar a influência do material de origem nos valores de ΧBF da terra fina seca ao ar (TFSA de amostras do horizonte B de solos do Paraná. As amostras foram coletadas em todo o Estado, num total de 45 pontos. Na TFSA foram determinados os valores de BF e da porcentagem da frequência dependente da suscetibilidade magnética (ΧFD. Os valores de suscetibilidade magnética dos solos formados sobre rochas eruptivas básicas foram significativamente maiores (1.000 a 7.800 x 10-8 m³ kg-1 que os encontrados em solos formados sobre rochas metamórficas e sedimentares (menores do que 500 x 10-8 m³ kg-1, demonstrando a influência do material de origem na presença de minerais ferrimagnéticos. Os valores de ΧFD indicaram a presenca de partículas superparamagnéticas (maghemita na maioria dos solos paranaenses.The ferrimagnetic minerals maghemite (γFe2O3 are closely related with metal availability and P adsorption capacity. Magnetization is spontaneous in a significant percentage of Brazilian soils. In the State of Paraná (Brazil this area represents up to 50 %. The determination of the mass-specific magnetic susceptibility (ΧBF is the simplest method of identification and quantification of ferrimagnetic

  19. ``Granite tectonics'' revisited: insights from comparison of K-feldspar shape-fabric, anisotropy of magnetic susceptibility (AMS), and brittle fractures in the Jizera granite, Bohemian Massif

    Science.gov (United States)

    Žák, Jiří; Verner, Kryštof; Klomínský, Josef; Chlupáčová, Marta

    2009-07-01

    In the Jizera granite of the Krkonoše-Jizera Plutonic Complex, northern Bohemian Massif, contrasting patterns of magmatic K-feldspar fabrics and brittle fractures characterize different structural levels of the pluton. The uppermost exposed level at ˜800-1,100 m above sea level is dominated by flat foliation that overprints two steep foliations. In contrast, K-feldspar shape-fabric in an underground tunnel (˜660 m above sea level) shows complex variations in orientation and intensity. Magnetic fabric carried by coaxial contributions of biotite, magnetite, and maghemite is homogeneous along the examined section of the tunnel, and is decoupled from the K-feldspar fabric. The Jizera granite is crosscut by two regional sets of subvertical fractures (˜NE-SW and ˜NW-SE) and by near-surface exfoliation joints. The multiple fabrics are inferred to reflect a complex magmatic strain history at different structural levels of the pluton, bearing little or no relationship to the fracture network. In contrast to the original concept of Hans Cloos (“granite tectonics”), we conclude that no simple genetic relationship exists between fabrics and fractures in plutons. An alternative classification of fractures in plutons thus should avoid relationships to magmatic fabrics and should instead consist of cooling, syntectonic, uplift, and post-uplift fractures.

  20. A stratigraphic network across the Subtropical Front in the central South Atlantic: Multi-parameter correlation of magnetic susceptibility, density, X-ray fluorescence and @d^1^8O records [rapid communication

    Science.gov (United States)

    Hofmann, Daniela I.; Fabian, Karl; Schmieder, Frank; Donner, Barbara; Bleil, Ulrich

    2005-12-01

    Computer aided multi-parameter signal correlation is used to develop a common high-precision age model for eight gravity cores from the subtropical and subantarctic South Atlantic. Since correlations between all pairs of multi-parameter sequences are used, and correlation errors between core pairs ( A, B) and ( B, C) are controlled by comparison with ( A, C), the resulting age model is called a stratigraphic network. Precise inter-core correlation is achieved using high-resolution records of magnetic susceptibility κ, wet bulk density ρ and X-ray fluorescence scans of elemental composition. Additional δ18O records are available for two cores. The data indicate nearly undisturbed sediment series and the absence of significant hiatuses or turbidites. After establishing a high-precision common depth scale by synchronously correlating four densely measured parameters (Fe, Ca, κ, ρ), the final age model is obtained by simultaneously fitting the aligned δ18O and κ records of the stratigraphic network to orbitally tuned oxygen isotope [J. Imbrie, J. D. Hays, D. G. Martinson, A. McIntyre, A. C. Mix, J. J. Morley, N. G. Pisias, W. L. Prell, N. J. Shackleton, The orbital theory of Pleistocene climate: support from a revised chronology of the marine δ18O record, in: A. Berger, J. Imbrie, J. Hays, G. Kukla, B. Saltzman (Eds.), Milankovitch and Climate: Understanding the Response to Orbital Forcing, Reidel Publishing, Dordrecht, 1984, pp. 269-305; D. Martinson, N. Pisias, J. Hays, J. Imbrie, T. C. Moore Jr., N. Shackleton, Age dating and the orbital theory of the Ice Ages: development of a high-resolution 0 to 300.000-Year chronostratigraphy, Quat. Res. 27 (1987) 1-29.] or susceptibility stacks [T. von Dobeneck, F.Schmieder, Using rock magnetic proxy records for orbital tuning and extended time series analyses into the super-and sub-Milankovitch Bands, in: G. Fischer, G. Wefer (Eds.), Use of proxies in paleoceanography: Examples from the South Atlantic, Springer

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-10-15

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

  2. 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.

  3. Superconductivity, magnetic susceptibility, and electronic properties of amorphous (Mo/sub 1-x/Ru/sub x/)/sub 80/P/sub 20/ alloys obtained by liquid quenching

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, W.L.; Poon, S.J.; Duwez, P.

    1977-11-01

    Results of x-ray diffraction, transmission electron diffraction, and crystallization studies on amorphous (Mo/sub 1-x/Ru/sub x/)/sub 80/P/sub 20/ alloys obtained by liquid quenching are presented and discussed. The alloys are all found to be superconducting with transition temperatures ranging from approximately 3/sup 0/K to approximately 9/sup 0/K. The variation of T/sub c/ with alloy composition is compared to that obtained by Collver and Hammond for vapor quenched transition metal films. Results of magnetic susceptibility measurements are used to estimate the variation of the electronic density of states at the Fermi level, N(0), from the Pauli paramagnetic contribution. The relationship between the variation of T/sub c/ and N(0) is discussed in terms of the microscope theory of superconductivity. Finally, results of measurements of the upper critical field H/sub c2/, and the normal state electronic transport properties are presented and compared with recent theoretical models for amorphous superconductors.

  4. Solvent-Induced Change of Electronic Spectra and Magnetic Susceptibility of Co(II) Coordination Polymer with 2,4,6-Tris(4-pyridyl)-1,3,5-triazine.

    Science.gov (United States)

    Polunin, Ruslan A; Burkovskaya, Nataliya P; Satska, Juliya A; Kolotilov, Sergey V; Kiskin, Mikhail A; Aleksandrov, Grigory G; Cador, Olivier; Ouahab, Lahcène; Eremenko, Igor L; Pavlishchuk, Vitaly V

    2015-06-01

    One-dimensional coordination polymer [Co(Piv)2(4-ptz)(C2H5OH)2]n (compound 1, Piv(-) = pivalate, 4-ptz = 2,4,6-tris(4-pyridyl)-1,3,5-triazine) was synthesized by interaction of Co(II) pivalate with 4-ptz. Desolvation of 1 led to formation of [Co(Piv)2(4-ptz)]n (compound 2), which adsorbed N2 and H2 at 78 K as a typical microporous sorbent. In contrast, absorption of methanol and ethanol by 2 at 295 K led to structural transformation probably connected with coordination of these alcohols to Co(II). Formation of 2 from 1 was accompanied by change of color of sample from orange to brown and more than 2-fold decrease of molar magnetic susceptibility (χM) in the temperature range from 2 to 300 K. Resolvation of 2 by ethanol or water resulted in restoration of spectral characteristics and χM values almost to the level of that of 1. χMT versus T curves for 1 and samples, obtained by resolvation of 2 by H2O or C2H5OH, were fitted using a model for Co(II) complex with zero-field splitting of this ion.

  5. Fast nonlinear susceptibility inversion with variational regularization.

    Science.gov (United States)

    Milovic, Carlos; Bilgic, Berkin; Zhao, Bo; Acosta-Cabronero, Julio; Tejos, Cristian

    2018-01-10

    Quantitative susceptibility mapping can be performed through the minimization of a function consisting of data fidelity and regularization terms. For data consistency, a Gaussian-phase noise distribution is often assumed, which breaks down when the signal-to-noise ratio is low. A previously proposed alternative is to use a nonlinear data fidelity term, which reduces streaking artifacts, mitigates noise amplification, and results in more accurate susceptibility estimates. We hereby present a novel algorithm that solves the nonlinear functional while achieving computation speeds comparable to those for a linear formulation. We developed a nonlinear quantitative susceptibility mapping algorithm (fast nonlinear susceptibility inversion) based on the variable splitting and alternating direction method of multipliers, in which the problem is split into simpler subproblems with closed-form solutions and a decoupled nonlinear inversion hereby solved with a Newton-Raphson iterative procedure. Fast nonlinear susceptibility inversion performance was assessed using numerical phantom and in vivo experiments, and was compared against the nonlinear morphology-enabled dipole inversion method. Fast nonlinear susceptibility inversion achieves similar accuracy to nonlinear morphology-enabled dipole inversion but with significantly improved computational efficiency. The proposed method enables accurate reconstructions in a fraction of the time required by state-of-the-art quantitative susceptibility mapping methods. Magn Reson Med, 2018. © 2018 International Society for Magnetic Resonance in Medicine. © 2018 International Society for Magnetic Resonance in Medicine.

  6. 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

  7. 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.

  8. Stratigraphic variation of complex impurities in platform limestones and possible significance of atmospheric dust: a study with emphasis on gamma-ray spectrometry and magnetic susceptibility outcrop logging (Eifelian-Frasnian, Moravia, Czech Republic)

    Science.gov (United States)

    Hladil, J.; Gersl, M.; Strnad, L.; Frana, J.; Langrova, A.; Spisiak, J.

    2006-07-01

    Mineral dust and other constituents of Devonian atmospheric aerosols together with certain amounts of aquatic suspensions of riverine detrital origin, colloidal particle dispersions and seawater solutes were embedded in ~95-98% (or purer) limestones on a consistently subsiding isolated carbonate platform where they formed very complex impurity systems. Very low Th/U values, relative abundance of Fe but a slight excess of K typically characterize these ultrafine impurities which are mineralogically dominated by smectite-illite and mica (sericite) together with goethite. In vertical section, these impurities are arranged like incremental series of light and dense bands. The combined method of natural gamma-ray spectrometric and magnetic susceptibility measurements (GRS-MS) together with background of major and trace element analyses provided first systematic insights into fine-scale variability of these impurities in a pile of pure carbonate platform beds, mostly in inner platform Amphipora limestone facies. These carbonates were deposited close to sea level but far from river mouths, and they represented a certain sort of a relatively “independent” medium that was primarily sensitive to climatically (and by rare events) controlled input of atmospheric dust. A remarkable similarity of MS stratigraphic patterns that reflect the quantity and quality of embedded impurities in very distant and paleogeographically separated Devonian basins might be seen as supporting this viewpoint. A long composite stratigraphic section of the Moravian Karst ranges from mid-Eifelian to end-Frasnian levels and yields a number of time characterizing GRS-MS variations that can potentially serve as templates for high-resolution stratigraphic correlations over long distances.

  9. Zinc-induced modification of the dynamical magnetic susceptibility in the superconducting state of YBa{sub 2}Cu{sub 3}O{sub 6+}{sub {ital x}} as revealed by inelastic neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Sidis, Y.; Bourges, P.; Hennion, B. [Laboratoire Leon Brillouin, CEA-CNRS, Centre dEtudes de Saclay, 91191 Gif-sur-Yvette (France); Regnault, L.P. [Centre dEtudes Nucleaires de Grenoble, Departement de Recherche Fondamentale sur la Matiere Condensee, Service de Physique Statistique, Magnetisme et Supraconductivite, Groupe Magnetisme et Diffraction Neutronique, 85 X, 38041 Grenoble cedex (France); Villeneuve, R.; Collin, G. [Laboratoire Leon Brillouin, CEA-CNRS, Centre dEtudes de Saclay, 91191 Gif-sur-Yvette (France); Marucco, J.F. [Laboratoire des Composes Non-Stoechiometriques, CNRS URA 446, Batiment 415, Universite Paris Sud centre dOrsay, Orsay (France)

    1996-03-01

    Inelastic-neutron-scattering measurements have been performed to determine the imaginary part of the dynamical susceptibility, {chi}{double_prime}({ital Q},{omega}), of a YBa{sub 2}(Cu{sub 1{minus}{ital y}}Zn{sub {ital y}}){sub 3}O{sub 6.97} sample exhibiting a superconducting transition at {ital T}{sub {ital c}}=69 K. Zinc substitution induces striking modifications of the energy dependence of {chi}{double_prime}({ital Q},{omega}) but magnetic fluctuations remain peaked at the antiferromagnetic wave vector, {ital Q}{sub AF}, at all investigated energies. In the superconducting state of the zinc-free compound, {chi}{double_prime}({ital Q},{omega}) is restricted to a narrow energy range, {h_bar}{omega}=33{endash}47 meV, displaying a {ital spin} {ital gap} at {ital E}{sub {ital G}}=33 meV and a resonant enhancement at {ital E}{sub {tau}}=39 meV, both features vanishing upon heating up above {ital T}{sub {ital c}}. In the {ital y}=0.02 substituted sample in the superconducting state, there is still an energy band in the range 32{endash}47 meV but no clear resonance, and a signal is now observed in the low energy range, though the line shape of {chi}{double_prime}({ital Q},{omega}) indicates some reminiscence of the spin gap of the pure compound. {copyright} {ital 1996 The American Physical Society.}

  10. Susceptibility of superconductors via scattering approach

    Czech Academy of Sciences Publication Activity Database

    Janů, Zdeněk; Soukup, František; Tichý, Rudolf; Tsoi, G. M.; Hadač, J.; Vejpravová, J.

    2004-01-01

    Roč. 54, Suppl. D (2004), s. 437-441 ISSN 0011-4626 R&D Projects: GA ČR GA102/02/0994; GA AV ČR KSK1010104 Institutional research plan: CEZ:AV0Z1010914 Keywords : superconductivity * susceptibility * electron scattering Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.292, year: 2004

  11. Extracting remanent magnetization from magnetic data inversion

    Science.gov (United States)

    Liu, S.; Fedi, M.; Baniamerian, J.; Hu, X.

    2017-12-01

    Remanent magnetization is an important vector parameter of rocks' and ores' magnetism, which is related to the intensity and direction of primary geomagnetic fields at all geological periods and hence shows critical evidences of geological tectonic movement and sedimentary evolution. We extract the remanence information from the distributions of the inverted magnetization vector. Firstly, directions of total magnetization vector are estimated from reduced-to-pole anomaly (max-min algorithm) and by its correlations with other magnitude magnetic transforms such as magnitude magnetic anomaly and normalized source strength. Then we invert data for the magnetization intensity and finally the intensity and direction of the remanent magnetization are separated from the total magnetization vector with a generalized formula of the apparent susceptibility based on a priori information on the Koenigsberger ratio. Our approach is used to investigate the targeted resources and geologic processes of the mining areas in China.

  12. Electrically Tunable Magnetism in Magnetic Topological Insulators

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jing; Lian, Biao; Zhang, Shou-Cheng

    2015-07-14

    The external controllability of the magnetic properties in topological insulators would be important both for fundamental and practical interests. Here we predict the electric-field control of ferromagnetism in a thin film of insulating magnetic topological insulators. The decrease of band inversion by the application of electric fields results in a reduction of magnetic susceptibility, and hence in the modification of magnetism. Remarkably, the electric field could even induce the magnetic quantum phase transition from ferromagnetism to paramagnetism. We further propose a transistor device in which the dissipationless charge transport of chiral edge states is controlled by an electric field. In particular, the field-controlled ferromagnetism in a magnetic topological insulator can be used for voltage based writing of magnetic random access memories in magnetic tunnel junctions. The simultaneous electrical control of magnetic order and chiral edge transport in such devices may lead to electronic and spintronic applications for topological insulators.

  13. Environmental magnetic and geochemical characteristics of ...

    Indian Academy of Sciences (India)

    ... ARM and SIRM) for the polluted samples with magnetic susceptibility excess of 50 × 10−8 m3kg−1. Significant correlations between heavy metals and magnetic susceptibility point out the potential of magnetic screening/monitoring for simple and rapid proxy indicator of heavy metal pollution in marine sediments.

  14. Demagnetization treatment of remanent composite microspheres studied by alternating current susceptibility measurements

    NARCIS (Netherlands)

    van Berkum, S.; Erné, B.H.

    2013-01-01

    The magnetic remanence of silica microspheres with a low concentration of embedded cobalt ferrite nanoparticles is studied after demagnetization and remagnetization treatments. When the microspheres are dispersed in a liquid, alternating current (AC) magnetic susceptibility spectra reveal a constant

  15. Remanent magnetization of instrument materials for low magnetic field applications

    International Nuclear Information System (INIS)

    Mester, J.C.; Lockhart, J.M.

    1996-01-01

    We report remanent magnetization and magnetic susceptibility measurements made on materials used in the construction of cryogenic instruments. SQUID based magnetometers were used to make the measurements over a range of background fields from 10 2 to 10 -7 Gauss. Although the materials tested are generally regarded as non-magnetic, some samples have sufficiently high magnetization values, or values which vary with foundry lot and heat, that use in low field or magnetically sensitive applications is contraindicated. (author)

  16. Cementation of kerogen-rich marls by alkaline fluids released during weathering of thermally metamorphosed marly sediments. Part II: Organic matter evolution, magnetic susceptibility and metals (Ti, Cr, Fe) at the Khushaym Matruk natural analogue (Central Jordan)

    Energy Technology Data Exchange (ETDEWEB)

    Elie, M. [Univ Nancy 1, CNRS, F-54506 Vandoeuvre Les Nancy (France); Techer, I. [Univ Aix Marseille 3, CNRS, UMR 6635, CEREGE, F-30035 Nimes, (France); Trotignon, L. [CEN Cadarache, DTN SMTM LMTE, F-13108 St Paul Les Durance (France); Khoury, H.; Salameh, E. [Univ Jordan, Dept Geol, Amman 11942 (Jordan); Vandamme, D. [Univ Aix Marseille 3, CNRS, UMR 6635, CEREGE, F-13545 Aix En Provence (France); Boulvais, P.; Fourcade, S. [Univ Rennes 1, CNRS, UMR 6118, F-35042 Rennes (France)

    2007-07-15

    Spontaneous combustion, less than 1 Ma ago, affected a 60-m thick sediment pile of bio-micrite at the Khushaym Matruck site (Jordan). The present study shows that three retrograde alteration stages occurred: weathering, thermal stress and oxidative alkaline perturbation. {mu}-FT-i.r. spectra of isolated kerogens and oxygen index of whole rocks indicate that oxidation of organic matter occurred down to similar to 10 m beneath the metamorphosed zone at Khushaym Matruck. The occurrence of the oxidative weathering bacterially mediated, as suggested by the mass chromatograms of saturated hydrocarbons, can explain high Rock-Eval T{sub max} values and low petroliferous potential measured along the sedimentary pile. On the other hand, the thermal extent of combustion events was limited to the first 2 m from the contact. The mean reflectance of 0.20-0.24% and porosity of ca. 50% of the grey clayey bio-micrites indicate that organic matter was very immature and sediments were unconsolidated at the time of the combustion event. Using mineralogy, microscopic analyses of vegetable debris and magnetic susceptibility, a suite of characteristic points corresponding to the thermal imprint can be assessed: (i) x = 0 m, T similar to 1000 degrees C, (ii) x 1 m, T similar to 350 degrees C, (iii) x = 2 m, T similar to 150 degrees C and (iv) x {>=} {approx} 8 m, T similar to 30 degrees C. Paleo-circulation of meteoric groundwater in the 'cement-marbles' generated high-pH fluids that have circulated via fractures and through the matrix porosity of the underlying bio-micrites but have also induced alkaline hydrolysis and oxidative attack of the organic matter. The polysaccharide/lignin ratio derived from mu-FT-i.r. analyses shows that the delignification of vegetable debris and degradation of polysaccharides progressively decline in the indurated zone, which indicates a decrease in the pH of migrating solutions. The latter, also severely oxidized organic matter at 2. 10 and 3

  17. 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)

  18. Loess magnetism

    Science.gov (United States)

    Heller, Friedrich; Evans, Michael E.

    Loess is a wind-blown Quaternary silt deposit that blankets vast tracts of land and in places reaches thicknesses in excess of 300 m. Over the last decade it has emerged that certain loess sections have recorded the polarity history of the geomagnetic field and now provide essentially continuous magnetostratigraphic archives covering the last 2-3 m.y. Indeed, it is the chronology provided by the magnetic polarity signature itself that was largely responsible for establishing the timing of the initiation of loess accumulation, particularly in the celebrated Chinese loess plateau, where a starting date close to the Gauss-Matuyama chron boundary (2.6 Ma) is now firmly established. This coincides with a widely documented global climatic shift and accelerated uplift of the Tibetan planteau. Many loess sections contain fossil soils (paleosols) that bear witness to warmer and wetter climatic conditions corresponding to interglacial periods in contrast to the cold, arid environments in which pristine loess accumulated and which correspond to glacial intervals. The resulting sequences of alternating loess and paleosols also manifest themselves magnetically, in this case in terms of susceptibility changes, entirely distinct from the remanence characteristics, which encode the geomagnetic polarity. The susceptibility time series obtained from localities in Alaska and China correlate remarkably well with the oceanic oxygen isotope signal and yield spectral power estimates in agreement with those predicted by the astronomical (Milankovitch) theory of ice ages. Comparisons of susceptibility patterns with corresponding profiles of 10Be concentration in loess allows major changes in rainfall to be estimated. In China, for example data spanning the last 130 kyr (corresponding to oxygen isotope stages 1-5) indicate that paleoprecipitation was almost halved (from ≃540 to ≃310 mm yr-1) as the warm interglacial during which paleosol S1 formed gave way to the following glacial

  19. 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

  20. 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.

  1. Interaction between two magnetic dipoles in a uniform magnetic field

    Science.gov (United States)

    Ku, J. G.; Liu, X. Y.; Chen, H. H.; Deng, R. D.; Yan, Q. X.

    2016-02-01

    A new formula for the interaction force between two magnetic dipoles in a uniform magnetic field is derived taking their mutual magnetic interaction into consideration and used to simulate their relative motion. Results show that when the angle β between the direction of external magnetic field and the centerline of two magnetic dipoles is 0 ° or 90 °, magnetic dipoles approach each other or move away from each other in a straight line, respectively. And the time required for them to contact each other from the initial position is related to the specific susceptibility and the diameter of magnetic particles, medium viscosity and magnetic field strength. When β is between 0 ° and 90 °, magnetic dipole pair performs approximate elliptical motion, and the motion trajectory is affected by the specific susceptibility, diameter and medium viscosity but not magnetic field strength. However, time required for magnetic dipoles to complete the same motion trajectory is shorter when adopting stronger magnetic field. Moreover, the subsequent motion trajectory of magnetic dipoles is ascertained once the initial position is set in a predetermined motion trajectory. Additionally, magnetic potential energy of magnetic dipole pairs is transformed into kinetic energy and friction energy during the motion.

  2. Interaction between two magnetic dipoles in a uniform magnetic field

    Directory of Open Access Journals (Sweden)

    J. G. Ku

    2016-02-01

    Full Text Available A new formula for the interaction force between two magnetic dipoles in a uniform magnetic field is derived taking their mutual magnetic interaction into consideration and used to simulate their relative motion. Results show that when the angle β between the direction of external magnetic field and the centerline of two magnetic dipoles is 0 ° or 90 °, magnetic dipoles approach each other or move away from each other in a straight line, respectively. And the time required for them to contact each other from the initial position is related to the specific susceptibility and the diameter of magnetic particles, medium viscosity and magnetic field strength. When β is between 0 ° and 90 °, magnetic dipole pair performs approximate elliptical motion, and the motion trajectory is affected by the specific susceptibility, diameter and medium viscosity but not magnetic field strength. However, time required for magnetic dipoles to complete the same motion trajectory is shorter when adopting stronger magnetic field. Moreover, the subsequent motion trajectory of magnetic dipoles is ascertained once the initial position is set in a predetermined motion trajectory. Additionally, magnetic potential energy of magnetic dipole pairs is transformed into kinetic energy and friction energy during the motion.

  3. The Pragian-Emsian strata of Kitab Reserve and Barrandian Area: The 2008 SDS research task on magnetic susceptibility logs and their stratigraphic correlation by means of the dynamic time warping techniques

    Czech Academy of Sciences Publication Activity Database

    Hladil, Jindřich; Vondra, Martin; Slavík, Ladislav; Koptíková, Leona; Čejchan, Petr; Vích, Robert

    -, č. 26 (2011), s. 54-56 ISSN 2074-7268 R&D Projects: GA AV ČR IAAX00130702 Institutional research plan: CEZ:AV0Z30130516; CEZ:AV0Z20670512 Keywords : dynamic time warping * magnetic suscpetibility * stratigraphy * Lower Devonian Subject RIV: DE - Earth Magnetism, Geodesy, Geography http://unica2.unica.it/ sds /images/ SDS 26%20-%202011.pdf

  4. 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.

  5. Magnetic susceptibility and specific heat of the one-dimensional conductor (H3O) sub (1,6) Pt (C2O4)2.nH2O at low temperatures

    International Nuclear Information System (INIS)

    Raede, H.S.

    1985-01-01

    It has been shown recently that some transition metal complexes exhibit one-dimensional metallic properties. It is reported, in this context, susceptibility and specific heat measurements of polycrystalline (H 3 O) 1 , 6 Pt(C 2 O 4 ) 2 .nH 2 O in the low temperature range. It is found that the susceptibility can be described by a non-uniform Curie law with a characteristic break in the slope. The specific heat reveals no linear temperature contribution, which could be explained by a transition into a Peierls distorted state. Until 13 0 K, the heat capacity follows a T 3 -law. Deviations at higher temperatures are possibly attributed to the anisotropy of the system [pt

  6. 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

  7. Fourie susceptible.pmd

    African Journals Online (AJOL)

    Prof. Adipala Ekwamu

    majority having adequate resistance. Teebus, Cerillos, Bonus and PAN 159 were most susceptible, with Mkuzi exhibiting highest levels of resistance. No correlation was obtained between disease rating and yield. Although a number of cultivars exhibited field resistance to halo blight and bacterial brown spot, all cultivars ...

  8. Dynamic susceptibility of nanopillars

    NARCIS (Netherlands)

    Dao, T.N.N.; Dao, N.; Donahue, M.J.; Dumitru, I.; Spinu, L.; Whittenburg, S.L.; Lodder, J.C.

    2004-01-01

    We have calculated the dynamic susceptibility of patterned cobalt and Permalloy pillars with a diameter of 50 nm and different pillar heights using micromagnetic simulations. The resonance modes obtained from these simulations are compared to the results obtained from an analytical solution of

  9. Genetic susceptibility of periodontitis

    NARCIS (Netherlands)

    Laine, M.L.; Crielaard, W.; Loos, B.G.

    2012-01-01

    In this systematic review, we explore and summarize the peer-reviewed literature on putative genetic risk factors for susceptibility to aggressive and chronic periodontitis. A comprehensive literature search on the PubMed database was performed using the keywords ‘periodontitis’ or ‘periodontal

  10. Pinning Susceptibility at the Jamming Transition

    Science.gov (United States)

    Graves, Amy; Padgett, Elliot; Goodrich, Carl; Liu, Andrea

    2013-03-01

    Jamming in the presence of fixed or pinned obstacles, representing quenched disorder, is a situation of both practical and theoretical interest. We study the jamming of soft, bidisperse discs in which a subset of discs are pinned while the remaining particles equilibrate around them at a given volume fraction. The obstacles provide a supporting structure for the jammed configuration which not only lowers the jamming threshold, ϕJ, but affects the coordination number and other parameters of interest as the critical point is approached. In the limit of low obstacle density, one can calculate a pinning susceptibility χP, analogous to the magnetic susceptibility, with obstacle density playing the role of the magnetic field. The pinning susceptibility is thus expected to diverge in the thermodynamic limit as χP ~| ϕ -ϕJ | -γP . Finite-size scaling calculations allow us to confirm this and calculate the critical exponent, γP. Acknowledgement is made to the Donors of the Petrolium Research Fund administered by the American Chemical Society, Swarthmore College's Eugene M. Lang Faculty Fellowship, NSF grant DMR-1062638 and DOE grant DE-FG02-05ER46199.

  11. Genetic Susceptibility to Atherosclerosis

    Directory of Open Access Journals (Sweden)

    Sanja Kovacic

    2012-01-01

    Full Text Available Atherosclerosis is a complex multifocal arterial disease involving interactions of multiple genetic and environmental factors. Advances in techniques of molecular genetics have revealed that genetic ground significantly influences susceptibility to atherosclerotic vascular diseases. Besides further investigations of monogenetic diseases, candidate genes, genetic polymorphisms, and susceptibility loci associated with atherosclerotic diseases have been identified in recent years, and their number is rapidly increasing. This paper discusses main genetic investigations fields associated with human atherosclerotic vascular diseases. The paper concludes with a discussion of the directions and implications of future genetic research in arteriosclerosis with an emphasis on prospective prediction from an early age of individuals who are predisposed to develop premature atherosclerosis as well as to facilitate the discovery of novel drug targets.

  12. Relationship between the complex susceptibility and the plasma dispersion function

    International Nuclear Information System (INIS)

    Jimenez D, H.; Cabral P, A.

    1991-04-01

    It is shown that when magnetization processes in a spin system and resonant excitation of spin n states occur in the presence of internal and or external random line-broadening mechanisms, the complex magnetic susceptibility of the plasma dispersion function. letter could be useful spin in system is proportional to the relationship found in this spectroscopies such as EPR and NMR, for example, as its fitting to experimental absorption and dispersion profiles produces their Lorentzian and Gaussian contents. (Author)

  13. Relationship between the complex susceptibility and the plasma dispersion function

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez D, H.; Cabral P, A

    1991-04-15

    It is shown that when magnetization processes in a spin system and resonant excitation of spin n states occur in the presence of internal and or external random line-broadening mechanisms, the complex magnetic susceptibility of the plasma dispersion function. letter could be useful spin in system is proportional to the relationship found in this spectroscopies such as EPR and NMR, for example, as its fitting to experimental absorption and dispersion profiles produces their Lorentzian and Gaussian contents. (Author)

  14. Marijuana Usage and Hypnotic Susceptibility

    Science.gov (United States)

    Franzini, Louis R.; McDonald, Roy D.

    1973-01-01

    Anonymous self-reported drug usage data and hypnotic susceptibility scores were obtained from 282 college students. Frequent marijuana users (more than 10 times) showed greater susceptibility to hypnosis than nonusers. (Author)

  15. A Solid State Nanopore Device for Investigating the Magnetic Properties of Magnetic Nanoparticles

    Directory of Open Access Journals (Sweden)

    SangYoon Park

    2013-05-01

    Full Text Available In this study, we explored magnetic nanoparticles translocating through a nanopore in the presence of an inhomogeneous magnetic field. By detecting the ionic current blockade signals with a silicon nitride nanopore, we found that the translocation velocity that is driven by magnetic and hydrodynamic forces on a single magnetic nanoparticle can be accurately determined and is linearly proportional to the magnetization of the magnetic nanoparticle. Thus, we obtained the magneto-susceptibility of an individual nanoparticle and the average susceptibility over one hundred particles within a few minutes.

  16. 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

  17. Validation of a quantitative susceptibility mapping acquisition and reconstruction pipeline using a new iron sucrose based MR susceptibility phantom.

    Science.gov (United States)

    Deverdun, Jeremy; Molino, François; Menjot de Champfleur, Nicolas; Le Bars, Emmanuelle

    2017-07-01

    Quantitative susceptibility mapping is a new technique and its processing pipeline has to be validated before clinical practice. We described an easy to build magnetic resonance (MR) susceptibility phantom based on iron sucrose. In a plastic container, Eppendorf tubes containing increasing iron sucrose concentration ranging from 0 to 60μg Fe/mL were inserted in an agarose gel. To estimate susceptibility, multiple coronal gradient echo acquisitions were performed with varying angle of the phantom relative to the B 0 field, ranging from 30 to 90°. Quantitative susceptibility maps were reconstructed using the l 1 and l 2 norm of total variation using Split Bregman approach. Iron concentration was finally estimated from the susceptibility in the tubes. In l 1 norm susceptibility and estimated iron concentration were not different from the real values while l 2 norm underestimated the susceptibility. A correlation was found between the angle of the phantom and the difference between real and estimated iron concentrations. The results highlight the importance of this validation by emphasizing the effects of various reconstruction parameters as well as acquisition conditions. Using optimal parameters, the quantitative susceptibility mapping provides a very good estimation of the iron concentrations in the phantom. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  18. Single-ion anisotropy and exchange interactions in the cyano-bridged trimers MnIII2MIII(CN)6 (MIII = Co, Cr, Fe) species incorporating [Mn(5-Brsalen)]+ units: an inelastic neutron scattering and magnetic susceptibility study

    DEFF Research Database (Denmark)

    Tregenna-Piggott, Philip L W; Sheptyakov, Denis; Keller, Lukas

    2009-01-01

    expectations based on the unquenched orbital angular momentum of the [Fe(CN)(6)](3-) anion, giving rise to an M(s) approximately +/-9/2 ground state, isolated by approximately 11.5 cm(-1) from the higher-lying levels. The reported INS and magnetic data should now serve as a benchmark against which theoretical...... interactions that define the low-lying states of the Mn-M(III)-Mn trimeric units. Despite the presence of an antiferromagnetic intertrimer interaction, the experimental evidence supports the classification of both the Cr(III) and Fe(III) compounds as single-molecule magnets. The value of 17(2) cm(-1...

  19. Effects of air susceptibility on proton resonance frequency MR thermometry.

    Science.gov (United States)

    Streicher, Markus N; Schäfer, Andreas; Reimer, Enrico; Dhital, Bibek; Trampel, Robert; Ivanov, Dimo; Turner, Robert

    2012-02-01

    The temperature dependence of the proton resonance frequency (PRF) is often used in MR thermometry. However, this method is prone to even very small changes in local magnetic field strength. Here, we report on the effects of susceptibility changes of surrounding air on the magnetic field inside an object and their inferred effect on the measured MR temperature. MR phase thermometry was performed on spherical agar phantoms enclosed in cylindrical containers at 7 T. The air susceptibility inside the cylindrical container was changed by both heating the air and changing the gas composition. Changing the temperature of surrounding air from 23 to 69°C caused an apparent MR temperature error of 2 K. When ambient air was displaced by 100% oxygen, the MR temperature error increased to 40 K. The magnetic field shift and therefore error in inferred MR temperature scales linearly with volume susceptibility change and has a strong and nontrivial dependence on the experimental configuration. Air susceptibility changes associated with oxygen concentration changes greatly affect PRF MR thermometry measurements. Air temperature changes can also affect these measurements, but to a smaller degree. For uncalibrated MR thermometry, air susceptibility changes may be a significant source of error.

  20. Measuring iron in the brain using quantitative susceptibility mapping and X-ray fluorescence imaging.

    Science.gov (United States)

    Zheng, Weili; Nichol, Helen; Liu, Saifeng; Cheng, Yu-Chung N; Haacke, E Mark

    2013-09-01

    Measuring iron content in the brain has important implications for a number of neurodegenerative diseases. Quantitative susceptibility mapping (QSM), derived from magnetic resonance images, has been used to measure total iron content in vivo and in post mortem brain. In this paper, we show how magnetic susceptibility from QSM correlates with total iron content measured by X-ray fluorescence (XRF) imaging and by inductively coupled plasma mass spectrometry (ICPMS). The relationship between susceptibility and ferritin iron was estimated at 1.10±0.08 ppb susceptibility per μg iron/g wet tissue, similar to that of iron in fixed (frozen/thawed) cadaveric brain and previously published data from unfixed brains. We conclude that magnetic susceptibility can provide a direct and reliable quantitative measurement of iron content and that it can be used clinically at least in regions with high iron content. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. 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.

  2. Phase processing for quantitative susceptibility mapping of regions with large susceptibility and lack of signal.

    Science.gov (United States)

    Fortier, Véronique; Levesque, Ives R

    2017-11-11

    Phase processing impacts the accuracy of quantitative susceptibility mapping (QSM). Techniques for phase unwrapping and background removal have been proposed and demonstrated mostly in brain. In this work, phase processing was evaluated in the context of large susceptibility variations (Δχ) and negligible signal, in particular for susceptibility estimation using the iterative phase replacement (IPR) algorithm. Continuous Laplacian, region-growing, and quality-guided unwrapping were evaluated. For background removal, Laplacian boundary value (LBV), projection onto dipole fields (PDF), sophisticated harmonic artifact reduction for phase data (SHARP), variable-kernel sophisticated harmonic artifact reduction for phase data (V-SHARP), regularization enabled sophisticated harmonic artifact reduction for phase data (RESHARP), and 3D quadratic polynomial field removal were studied. Each algorithm was quantitatively evaluated in simulation and qualitatively in vivo. Additionally, IPR-QSM maps were produced to evaluate the impact of phase processing on the susceptibility in the context of large Δχ with negligible signal. Quality-guided unwrapping was the most accurate technique, whereas continuous Laplacian performed poorly in this context. All background removal algorithms tested resulted in important phase inaccuracies, suggesting that techniques used for brain do not translate well to situations where large Δχ and no or low signal are expected. LBV produced the smallest errors, followed closely by PDF. Results suggest that quality-guided unwrapping should be preferred, with PDF or LBV for background removal, for QSM in regions with large Δχ and negligible signal. This reduces the susceptibility inaccuracy introduced by phase processing. Accurate background removal remains an open question. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  3. Magnetic anisotropy engineering in square magnetic elements

    International Nuclear Information System (INIS)

    Di Bona, A.; Contri, S.F.; Gazzadi, G.C.; Valeri, S.; Vavassori, P.

    2007-01-01

    Square magnetic elements with side in the 100-500 nm range have been fabricated using the focused ion beam (FIB) milling technique from a 10 nm thick, single-crystal Fe film, epitaxially grown on MgO(0 0 1). Thanks to the good crystal quality of the film, magnetic elements with well-defined magnetocrystalline anisotropy have been prepared, while the fine control of the size and shape of the magnets allows for the effective engineering of the anisotropic behavior of the magnetostatic energy that determines the so-called configurational anisotropy. Micromagnetic calculations and experiments show that the angular dependence of the transverse susceptibility has a strong dependence on the material parameters as well as on the static applied field. This allows the effective engineering of the total anisotropy of the magnets

  4. Magnetization of cobalt nanodiscs

    Science.gov (United States)

    Waddell, J.; Inderhees, S.; Aronson, M. C.; Dierker, S. B.

    2006-02-01

    We have studied the magnetization and AC susceptibility of a dilute colloidal dispersion of ɛ-Co nanodiscs. The temperature dependence of the magnetization implies that the nanodisc moments become largely static below a blocking temperature which exceeds room temperature. The related anisotropy energy is significantly larger than the magnetocrystalline anisotropy for bulk ɛ-Co, which may result either from surface modifications to the crystalline anisotropy, or perhaps from shape anisotropy. The saturation moment is found to be temperature independent, over a wide range of temperatures and also close to the blocking temperature, although the field at which saturation occurs varies considerably with temperature. A coercive field of 1700 Oe is found at low temperature, indicating that magnetization reversal involves the coordinated rotation of the moments in individual nanodiscs. Aging effects are observed in the AC susceptibility, implying that the spatial coherence of the room temperature dispersions increases over time, leading to static short-range order.

  5. Magnetization of cobalt nanodiscs

    Energy Technology Data Exchange (ETDEWEB)

    Waddell, J. [Department of Physics, University of Michigan, 500 East University Avenue, Ann Arbor, MI 48109-1120 (United States); Inderhees, S. [Department of Physics, University of Michigan, 500 East University Avenue, Ann Arbor, MI 48109-1120 (United States); Aronson, M.C. [Department of Physics, University of Michigan, 500 East University Avenue, Ann Arbor, MI 48109-1120 (United States)]. E-mail: maronson@umich.edu; Dierker, S.B. [Department of Physics, University of Michigan, 500 East University Avenue, Ann Arbor, MI 48109-1120 (United States); National Synchrotron Light Source, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States)

    2006-02-15

    We have studied the magnetization and AC susceptibility of a dilute colloidal dispersion of {epsilon}-Co nanodiscs. The temperature dependence of the magnetization implies that the nanodisc moments become largely static below a blocking temperature which exceeds room temperature. The related anisotropy energy is significantly larger than the magnetocrystalline anisotropy for bulk {epsilon}-Co, which may result either from surface modifications to the crystalline anisotropy, or perhaps from shape anisotropy. The saturation moment is found to be temperature independent, over a wide range of temperatures and also close to the blocking temperature, although the field at which saturation occurs varies considerably with temperature. A coercive field of 1700Oe is found at low temperature, indicating that magnetization reversal involves the coordinated rotation of the moments in individual nanodiscs. Aging effects are observed in the AC susceptibility, implying that the spatial coherence of the room temperature dispersions increases over time, leading to static short-range order.

  6. 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

  7. Brain Injury Lesion Imaging Using Preconditioned Quantitative Susceptibility Mapping without Skull Stripping.

    Science.gov (United States)

    Soman, S; Liu, Z; Kim, G; Nemec, U; Holdsworth, S J; Main, K; Lee, B; Kolakowsky-Hayner, S; Selim, M; Furst, A J; Massaband, P; Yesavage, J; Adamson, M M; Spincemallie, P; Moseley, M; Wang, Y

    2018-04-01

    Identifying cerebral microhemorrhage burden can aid in the diagnosis and management of traumatic brain injury, stroke, hypertension, and cerebral amyloid angiopathy. MR imaging susceptibility-based methods are more sensitive than CT for detecting cerebral microhemorrhage, but methods other than quantitative susceptibility mapping provide results that vary with field strength and TE, require additional phase maps to distinguish blood from calcification, and depict cerebral microhemorrhages as bloom artifacts. Quantitative susceptibility mapping provides universal quantification of tissue magnetic property without these constraints but traditionally requires a mask generated by skull-stripping, which can pose challenges at tissue interphases. We evaluated the preconditioned quantitative susceptibility mapping MR imaging method, which does not require skull-stripping, for improved depiction of brain parenchyma and pathology. Fifty-six subjects underwent brain MR imaging with a 3D multiecho gradient recalled echo acquisition. Mask-based quantitative susceptibility mapping images were created using a commonly used mask-based quantitative susceptibility mapping method, and preconditioned quantitative susceptibility images were made using precondition-based total field inversion. All images were reviewed by a neuroradiologist and a radiology resident. Ten subjects (18%), all with traumatic brain injury, demonstrated blood products on 3D gradient recalled echo imaging. All lesions were visible on preconditioned quantitative susceptibility mapping, while 6 were not visible on mask-based quantitative susceptibility mapping. Thirty-one subjects (55%) demonstrated brain parenchyma and/or lesions that were visible on preconditioned quantitative susceptibility mapping but not on mask-based quantitative susceptibility mapping. Six subjects (11%) demonstrated pons artifacts on preconditioned quantitative susceptibility mapping and mask-based quantitative susceptibility mapping

  8. Susceptibility to anchoring effects

    Directory of Open Access Journals (Sweden)

    Todd McElroy

    2007-02-01

    Full Text Available Previous research on anchoring has shown this heuristic to be a very robust psychological phenomenon ubiquitous across many domains of human judgment and decision-making. Despite the prevalence of anchoring effects, researchers have only recently begun to investigate the underlying factors responsible for how and in what ways a person is susceptible to them. This paper examines how one such factor, the Big-Five personality trait of openness-to-experience, influences the effect of previously presented anchors on participants' judgments. Our findings indicate that participants high in openness-to-experience were significantly more influenced by anchoring cues relative to participants low in this trait. These findings were consistent across two different types of anchoring tasks providing convergent evidence for our hypothesis.

  9. Topological susceptibility from slabs

    Energy Technology Data Exchange (ETDEWEB)

    Bietenholz, Wolfgang [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A.P. 70-543, Distrito Federal, C.P. 04510 (Mexico); Forcrand, Philippe de [Institute for Theoretical Physics, ETH Zürich,CH-8093 Zürich (Switzerland); CERN, Physics Department, TH Unit, CH-1211 Geneva 23 (Switzerland); Gerber, Urs [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A.P. 70-543, Distrito Federal, C.P. 04510 (Mexico); Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo,Edificio C-3, Apdo. Postal 2-82, Morelia, Michoacán, C.P. 58040 (Mexico)

    2015-12-14

    In quantum field theories with topological sectors, a non-perturbative quantity of interest is the topological susceptibility χ{sub t}. In principle it seems straightforward to measure χ{sub t} by means of Monte Carlo simulations. However, for local update algorithms and fine lattice spacings, this tends to be difficult, since the Monte Carlo history rarely changes the topological sector. Here we test a method to measure χ{sub t} even if data from only one sector are available. It is based on the topological charges in sub-volumes, which we denote as slabs. Assuming a Gaussian distribution of these charges, this method enables the evaluation of χ{sub t}, as we demonstrate with numerical results for non-linear σ-models.

  10. Topological Susceptibility from Slabs

    CERN Document Server

    Bietenholz, Wolfgang; Gerber, Urs

    2015-01-01

    In quantum field theories with topological sectors, a non-perturbative quantity of interest is the topological susceptibility chi_t. In principle it seems straightforward to measure chi_t by means of Monte Carlo simulations. However, for local update algorithms and fine lattice spacings, this tends to be difficult, since the Monte Carlo history rarely changes the topological sector. Here we test a method to measure chi_t even if data from only one sector are available. It is based on the topological charges in sub-volumes, which we denote as slabs. Assuming a Gaussian distribution of these charges, this method enables the evaluation of chi_t, as we demonstrate with numerical results for non-linear sigma-models.

  11. Magnetic susceptibility and ground-state zero-field splitting in high-spin mononuclear manganese(III) of inverted N-methylated porphyrin complexes: Mn(2-NCH3NCTPP)Br.

    Science.gov (United States)

    Hung, Sheng-Wei; Yang, Fuh-An; Chen, Jyh-Horung; Wang, Shin-Shin; Tung, Jo-Yu

    2008-08-18

    The crystal structures of diamagnetic dichloro(2-aza-2-methyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N',N'')-tin(IV) methanol solvate [Sn(2-NCH 3NCTPP)Cl 2.2(0.2MeOH); 6.2(0.2MeOH)] and paramagnetic bromo(2-aza-2-methyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N',N'')-manganese(III) [Mn(2-NCH 3NCTPP)Br; 5] were determined. The coordination sphere around Sn (4+) in 6.2(0.2MeOH) is described as six-coordinate octahedron ( OC-6) in which the apical site is occupied by two transoid Cl (-) ligands, whereas for the Mn (3+) ion in 5, it is a five-coordinate square pyramid ( SPY-5) in which the unidentate Br (-) ligand occupies the axial site. The g value of 9.19 (or 10.4) measured from the parallel polarization (or perpendicular polarization) of X-band EPR spectra at 4 K is consistent with a high spin mononuclear manganese(III) ( S = 2) in 5. The magnitude of axial ( D) and rhombic ( E) zero-field splitting (ZFS) for the mononuclear Mn(III) in 5 were determined approximately as -2.4 cm (-1) and -0.0013 cm (-1), respectively, by paramagnetic susceptibility measurements and conventional EPR spectroscopy. Owing to weak C(45)-H(45A)...Br(1) hydrogen bonds, the mononuclear Mn(III) neutral molecules of 5 are arranged in a one-dimensional network. A weak Mn(III)...Mn(III) ferromagnetic interaction ( J = 0.56 cm (-1)) operates via a [Mn(1)-C(2)-C(1)-N(4)-C(45)-H(45A)...Br(1)-Mn(1)] superexchange pathway in complex 5.

  12. 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.

  13. Magnetic properties and spin kinetics in Kondo lattices

    Directory of Open Access Journals (Sweden)

    S.I. Belov, A.S. Kutuzov

    2015-12-01

    Full Text Available We present a theoretical model to describe unusual properties of Kondo lattices. The influence of the Kondo effect on the static magnetic susceptibility and electron spin resonance (ESR parameters is studied in a simple molecular field approximation together with a scaling perturbative approach. Theoretical expressions well agree with the ESR and static magnetic susceptibility experimental data.

  14. 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

  15. Theoretical investigation of magnetic property in paramagnetic neodymium gallium garnet under high magnetic field

    International Nuclear Information System (INIS)

    Wang Wei; Liu Gongqiang; Wang Jinhui

    2006-01-01

    The magnetic property in neodymium gallium garnet (NdGaG) is studied by the quantum theory. The ground configuration split states are calculated taking into account the spin-orbit interaction and crystal field effect. Taking account of the Nd-Nd exchange interaction, a good agreement between experimental and theoretical values can be obtained for the variation of the magnetic moment with the external magnetic field under 'extreme' conditions (low temperature and high magnetic field). Moreover, the temperature dependence of magnetic moment and the magnetic susceptibility χ is also discussed. Above 30 K, the magnetization (M) shows a linear field (H e ) dependence

  16. Magnetic structures

    International Nuclear Information System (INIS)

    Oles, A.

    1976-01-01

    Description of progress in magnetic neutron diffraction gives an idea of its comtemporary possibilities. The most typical and interesting magnetic structures are presented. Magnetic structures symmetry is mentioned

  17. [Antimicrobial susceptibility in Chile 2012].

    Science.gov (United States)

    Cifuentes-D, Marcela; Silva, Francisco; García, Patricia; Bello, Helia; Briceño, Isabel; Calvo-A, Mario; Labarca, Jaime

    2014-04-01

    Bacteria antimicrobial resistance is an uncontrolled public health problem that progressively increases its magnitude and complexity. The Grupo Colaborativo de Resistencia, formed by a join of experts that represent 39 Chilean health institutions has been concerned with bacteria antimicrobial susceptibility in our country since 2008. In this document we present in vitro bacterial susceptibility accumulated during year 2012 belonging to 28 national health institutions that represent about 36% of hospital discharges in Chile. We consider of major importance to report periodically bacteria susceptibility so to keep the medical community updated to achieve target the empirical antimicrobial therapies and the control measures and prevention of the dissemination of multiresistant strains.

  18. AC susceptibility as a characterization tool for coated conductor tapes

    Science.gov (United States)

    Gömöry, F.; Vojenčiak, M.; Solovyov, M.; Frolek, L.; Šouc, J.; Seiler, E.; Bauer, M.; Falter, M.

    2017-11-01

    The measurement and analysis of magnetic AC susceptibility is a useful tool in the study of superconductor (SC) materials. Exposure of a sample to a magnetic field changing in time generates loops of electrical currents that are detectable in a contactless way with the help of a suitable pick-up system. In this paper the applicability of this technique in the characterization and quality control of coated conductor (CC) tapes is evaluated. First we recollect the essential results of the analytical theory derived for thin SC strips and their extrapolation to strips with finite thickness. From the analytical expressions one can see how the properties of CC tape that are important for application in electric power devices, namely its critical current and AC loss, can be deduced from AC susceptibility data in straightforward way. The main focus of our study is to investigate the influence that various cases of non-uniformities in SC layer exhibit on the magnetic properties examined in an AC regime. Numerical computations were used to explore the consequences of lateral variation in the critical current density. Predictions derived for some model cases were compared with experimental findings. A dedicated experiment was also carried out to demonstrate that a transverse scratch that would be detrimental for DC transport could sneak unobserved through the AC magnetic experiment on a long sample. Our study shows that the analysis of both parts of the complex magnetic susceptibility in place of a mere AC loss determination in a common AC magnetization experiment is worth the additional effort.

  19. 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)

  20. Measurement of the zero-field magnetic dipole moment of magnetizable colloidal silica spheres

    NARCIS (Netherlands)

    Claesson, E.M.; Erne, B.H.; Bakelaar, I.A.; Kuipers, B.W.M.; Philipse, A.P.

    2007-01-01

    The magnetic properties of dispersions of magnetic silica microspheres have been investigated by measuring the magnetization curves and the complex magnetic susceptibility as a function of frequency and field amplitude. The silica spheres appear to have a net permanent magnetic dipole moment, even

  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. Dynamic susceptibility of onion in ferromagnetic elliptical nanoring

    Science.gov (United States)

    Mu, Congpu; Song, Jiefang; Xu, Jianghong; Wen, Fusheng

    2016-06-01

    Micromagnetic simulation was performed to investigate the equilibrium state and dynamic susceptibility spectra of magnetic elliptical nanoring. There are two equilibrium states (onion and vortex) obtained in elliptical nanoring. The onion state can be used to record information in MRAM. And it is important to investigate the dynamic susceptibility spectra of onion state, which is closely related to writing and reading speed of magnetic memory devices. Those results show that two or three resonance peaks are found under different thickness of elliptical nanoring with onion state, respectively. The low resonance frequency of two resonance peaks is increasing with the arm width of the elliptical ring, but is decreasing with the thickness. However, the high frequency of two resonance peaks is decreasing with the arm width of the elliptical ring.

  3. Dynamic susceptibility of onion in ferromagnetic elliptical nanoring

    Directory of Open Access Journals (Sweden)

    Congpu Mu

    2016-06-01

    Full Text Available Micromagnetic simulation was performed to investigate the equilibrium state and dynamic susceptibility spectra of magnetic elliptical nanoring. There are two equilibrium states (onion and vortex obtained in elliptical nanoring. The onion state can be used to record information in MRAM. And it is important to investigate the dynamic susceptibility spectra of onion state, which is closely related to writing and reading speed of magnetic memory devices. Those results show that two or three resonance peaks are found under different thickness of elliptical nanoring with onion state, respectively. The low resonance frequency of two resonance peaks is increasing with the arm width of the elliptical ring, but is decreasing with the thickness. However, the high frequency of two resonance peaks is decreasing with the arm width of the elliptical ring.

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

    DEFF Research Database (Denmark)

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

    1997-01-01

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

  5. Hypnotic susceptibility and dream characteristics.

    Science.gov (United States)

    Zamore, N; Barrett, D

    1989-11-01

    This study examined the relationship of hypnotic susceptibility to a variety of dream characteristics and types of dream content. A Dream Questionnaire was constructed synthesizing Gibson's dream inventory and Hilgard's theoretical conceptions of hypnosis. Employing the Harvard Group Scale of Hypnotic Susceptibility and the Field Inventory for evaluating hypnotic response, several dream dimensions correlated significantly with hypnotizability. For subjects as a whole, the strongest correlates were the frequency of dreams which they believed to be precognitive and out-of-body dreams. Ability to dream on a chosen topic also correlated significantly with hypnotic susceptibility for both genders. For females only, there was a negative correlation of hypnotic susceptibility to flying dreams. Absorption correlated positively with dream recall, ability to dream on a chosen topic, reports of conflict resolution in dreams, creative ideas occurring in dreams, amount of color in dreams, pleasantness of dreams, bizarreness of dreams, flying dreams and precognitive dreams.

  6. Measuring Nematic Susceptibilities from the Elastoresistivity Tensor

    Science.gov (United States)

    Hristov, A. T.; Shapiro, M. C.; Hlobil, Patrick; Maharaj, Akash; Chu, Jiun-Haw; Fisher, Ian

    The elastoresistivity tensor mijkl relates changes in resistivity to the strain on a material. As a fourth-rank tensor, it contains considerably more information about the material than the simpler (second-rank) resistivity tensor; in particular, certain elastoresistivity coefficients can be related to thermodynamic susceptibilities and serve as a direct probe of symmetry breaking at a phase transition. The aim of this talk is twofold. First, we enumerate how symmetry both constrains the structure of the elastoresistivity tensor into an easy-to-understand form and connects tensor elements to thermodynamic susceptibilities. In the process, we generalize previous studies of elastoresistivity to include the effects of magnetic field. Second, we describe an approach to measuring quantities in the elastoresistivity tensor with a novel transverse measurement, which is immune to relative strain offsets. These techniques are then applied to BaFe2As2 in a proof of principle measurement. This work is supported by the Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, under Contract DE-AC02-76SF00515.

  7. Ancestral susceptibility to colorectal cancer

    Czech Academy of Sciences Publication Activity Database

    Huhn, S.; Pardini, Barbara; Naccarati, Alessio; Vodička, Pavel (ed.); Hemminki, K.; Försti, A.

    2012-01-01

    Roč. 27, č. 2 (2012), s. 197-204 ISSN 0267-8357 R&D Projects: GA ČR GA310/07/1430; GA ČR GAP304/10/1286 Grant - others:EU FP7(XE) HEALTH-F4-2007-200767 Institutional research plan: CEZ:AV0Z50390512 Keywords : cancer susceptibility * molecular epidemiology * genetic susceptibility Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.500, year: 2012

  8. 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.

  9. Magnetism and magnetic materials

    International Nuclear Information System (INIS)

    1990-01-01

    It describes the actual status of physics in Brazil concerning the study of magnetism and magnetic materials. It gives an overview of different research groups in Brazil, their needs, as well as the investments needed to improve the area. (A.C.A.S.)

  10. 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.

  11. Measurement of Radio Frequency Magnetic Field

    Czech Academy of Sciences Publication Activity Database

    Bartušek, Karel; Gescheidtová, E.

    2006-01-01

    Roč. 2, č. 6 (2006), s. 555-558 ISSN 1931-7360 R&D Projects: GA MZd NR8110 Institutional research plan: CEZ:AV0Z20650511 Keywords : MR tomographic scanner * magnetic susceptibility * body implants * mapping the radiofrequency magnetic field * ANSYS Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  12. Theory of anisotropic diamagnetism, local moment magnetization ...

    Indian Academy of Sciences (India)

    The relative spin-density of carriers increases with increase in the magnetic field strength and magnetic ion concentration. The agreement with experiment where ... susceptibility for a real system has always been a daunting exercise because of the enor- mous complexity associated with the problem. Pb1 xEuxTe is a ...

  13. Composite Microdiscs with a Magnetic Belt

    DEFF Research Database (Denmark)

    Knaapila, Matti; Høyer, Henrik; Helgesen, Geir

    2015-01-01

    , the spontaneous aggregation of composite particles is suppressed when dispersed into liquid, which is attributed to the increased particle size, reduced magnetic susceptibility, and the shape of the magnetic domain distribution within the particles (spherical versus a belt). When the composite particles...

  14. Deformable nematic droplets in a magnetic field

    NARCIS (Netherlands)

    Otten, R.H.J.; van der Schoot, P. P. A. M.

    2012-01-01

    We present a Frank-Oseen elasticity theory for the shape and structure of deformable nematic droplets with homeotropic surface anchoring in the presence of a magnetic field. Inspired by recent experimental observations, we focus on the case where the magnetic susceptibility is negative, and find

  15. Study of the magnetic superconductor, Y9Co7, at high pressure and high magnetic field

    International Nuclear Information System (INIS)

    Huang, C.Y.; Olsen, C.E.; Fuller, W.W.; Huang, J.H.; Wolf, S.A.

    1983-01-01

    The electrical resistance and magnetic susceptibility of the magnetic superconductor, Y 9 Co 7 has been measured at pressures up to 20 kbar and in magnetic fields up to 6T. It has been found that pressure suppresses the magnetism resulting in a higher superconducting transition temperature and conclude that Y 9 Co 7 is an itinerant ferromagnet, not a spin-glass. Pressure also sharpens the superconducting transition and increases the critical magnetic field, signifying that the long range ferromagnetic and superconducting order parameters co-exist but vary spatially. For pressures greater than 6 kbar, the magnetoresistance is always positive, further indicating the suppression of magnetism by high pressure. (author)

  16. Magnetic Properties of Dy in Pb

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-07-10

    Superconductivity can be induced at high temperatures in Pb{sub 2}Sr{sub 2}RCu{sub 3}O{sub 8} (R - rare earth) by partially doping Ca{sup 2+} for R{sup 3+}. In order to understand the interplay between magnetism and superconductivity, the magnetic properties of the parent compounds, Pb{sub 2}Sr{sub 2}RCu{sub 3}O{sub 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.

  17. Erosion factors and magnetic susceptibility in differet compartments of a slope in Gilbués-PI, Brazil Fatores de erosão e suscetibilidade magnética em diferentes compartimentos de uma vertente do município de Gilbués-PI

    Directory of Open Access Journals (Sweden)

    Hélio L. Santos

    2013-02-01

    Full Text Available The erosion is the degradation of soil with effects on crop productivity and pollution of the environment. To understand the spatial variability of this phenomenon, geostatistical techniques and concepts of soil-landscape can be used to identify landscape compartments with different potential of erosion. The aim of this study was to understand the factors of erosion in landscape compartments and the relations with the magnetic susceptibility (MS of the soils in a slope in Gilbués, state of Piauí (PI, Brazil. Sampling meshes were set in compartments I and II with 121 points and in compartment III with 99 points spaced every 10 meters. There was significant difference to erodibility (K and risk of erosion (RE; the spatial variability of MS was lower than the factors of soil erosion. The soil losses (A, the natural erosion potential (NEP, the RE and the MS had spatial relation with the topographic factor, indicating dependence of the erosion with the relief. We concluded that losses of soil, natural erosion potential and risk of erosion have spatial relation with the topographic factor, showing the dependence of the erosion factors with the relief. The soil magnetic susceptibility can be used as an auxiliary variable in the indirect quantification of the erodibility factor and the risk of soil erosion.A erosão é a forma de degradação do solo com efeitos na produtividade das culturas e na poluição do meio ambiente. Para compreender a variabilidade espacial desse fenômeno, técnicas geoestatísticas e conceitos da relação solo-paisagem podem ser utilizados para identificar compartimentos da paisagem com diferentes potenciais de erosão. O objetivo deste trabalho foi estabelecer elementos para a compreensão dos fatores de erosão em compartimentos da paisagem e das relações com a suscetibilidade magnética (SM dos solos de uma vertente no município de Gilbués -PI. Foram montadas malhas de amostragem nos compartimentos I e II, com 121

  18. Manipulating nonequilibrium magnetism through superconductors.

    Science.gov (United States)

    Giazotto, Francesco; Taddei, Fabio; Fazio, Rosario; Beltram, Fabio

    2005-08-05

    Electrostatic control of the magnetization of a normal mesoscopic conductor is analyzed in a hybrid superconductor-normal-conductor-superconductor system. This effect stems from the interplay between the nonequilibrium condition in the normal region and the Zeeman splitting of the quasi-particle density of states of the superconductor subjected to a static in-plane magnetic field. Unexpected spin-dependent effects such as magnetization suppression, diamagnetic-like response of the susceptibility, as well as spin-polarized current generation are the most remarkable features presented. The impact of scattering events is evaluated and lets us show that this effect is compatible with realistic material properties and fabrication techniques.

  19. Effect of pressure on magnetic properties of hexacyanochromates

    Czech Academy of Sciences Publication Activity Database

    Mitróová, Z.; MaŤaš, S.; Mihalik, M.; Zentková, M.; Arnold, Zdeněk; Kamarád, Jiří

    2008-01-01

    Roč. 113, č. 1 (2008), s. 469-472 ISSN 0587-4246 R&D Projects: GA AV ČR IAA100100632 Institutional research plan: CEZ:AV0Z10100521 Keywords : saturation moments and magnet ic susceptibilities * antiferromagnetics * molecular magnet Subject RIV: BM - Solid Matter Physics ; Magnet ism Impact factor: 0.321, year: 2008

  20. 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

  1. Crystal Fields and the Magnetic Properties of Praseodymium and Neodymium

    DEFF Research Database (Denmark)

    Johansson, Torben; Lebech, Bente; Nielsen, Mourits

    1970-01-01

    The magnetic properties of Pr and Nd single crystals have been studied by neutron-diffraction and susceptibility measurements. In contrast to earlier results on polycrystals, monocrystalline Pr is found not to be magnetically ordered, because of crystal field effects, but a magnetic field induces...

  2. Magnetic phase diagram of the UAs - USe system

    International Nuclear Information System (INIS)

    Obolenski, M.; Troc, R.

    1977-01-01

    The UAssub(1-x)Sesub(x) system was investigated in detail by means of magnetic susceptibility and magnetization measurements. For UAs the sharp transition on the chi vs. T curve at 41 K has been additionally found. For the compositions with x 0.55 all samples are ferro magnetic. (author)

  3. 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.

  4. Inherited susceptibility and radiation exposure

    International Nuclear Information System (INIS)

    Little, J.B.

    1997-01-01

    There is continuing concern that some people in the general population may have genetic makeups that place them at particularly high risk for radiation-induced cancer. The existence of such a susceptible subpopulation would have obvious implications for the estimation of risks of radiation exposure. Although it has been long known that familial aggregations of cancer do sometimes occur, recent evidence suggests that a general genetic predisposition to cancer does not exist; most cancers occur sporadically. On the other hand, nearly 10% of the known Mendelian genetic disorders are associated with cancer. A number of these involve a familial predisposition to cancer, and some are characterized by an enhanced susceptibility to the induction of cancer by various physical and chemical carcinogens, including ionizing radiation. Such increased susceptibility will depend on several factors including the frequency of the susceptibility gene in the population and its penetrance, the strength of the predisposition, and the degree to which the cancer incidence in susceptible individuals may be increased by the carcinogen. It is now known that these cancer-predisposing genes may be responsible not only for rare familial cancer syndromes, but also for a proportion of the common cancers. Although the currently known disorders can account for only a small fraction of all cancers, they serve as models for genetic predisposition to carcinogen-induced cancer in the general population. In the present report, the author describes current knowledge of those specific disorders that are associated with an enhanced predisposition to radiation-induced cancer, and discusses how this knowledge may bear on the susceptibility to radiation-induced cancer in the general population and estimates of the risk of radiation exposure

  5. pitting corrosion susceptibility pitting corrosion susceptibility of aisi ...

    African Journals Online (AJOL)

    eobe

    The susceptibility of austenitic (AISI 301) stainless steel to pitting corrosion was evaluated in sodium chloride ... halides, the most aggressive and thus, the most frequently investigated is the chloride ions, particularly its effect on pit formation in 18/8 stainless steel [1 - 3]. ... in sea water), and moderately high temperatures.

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

    Indian Academy of Sciences (India)

    Anaipadi calcarenite mem- ber follows the Kulkkalnattam member, comprises of shale, silt, limestone and sandstone with bands of calcareous grit and the Saturbhagam mem- ber in stratigraphic younging. The Garudaman- galam Formation is unconformably overlain by the. Sillakkudi Formation (Sundaram et al. 2001).

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

    African Journals Online (AJOL)

    Mohamed Masoud Radwan

    tumors, aging and multiple sclerosis'' (MS).1. 2. Methods. Thirty patients with known or suspected brain lesions were subjected to MRI examination using 1.5 T closed-configura- tion GE Signa HDxT and Avanto Siemens, according to the following parameters: T1: TR of 550 ms, a TE of 15 ms, a 256 × 256 acquisition matrix ...

  8. Study of Static Magnetic Properties of Transformer Oil Based Magnetic Fluids for Various Technical Applications Using Demagnetizing Field Correction

    Directory of Open Access Journals (Sweden)

    Oana Maria Marinica

    2017-01-01

    Full Text Available Static magnetization data of eight transformer oil based magnetic fluid samples, with saturation magnetization ranging in a large interval from 9 kA/m to 90 kA/m, have been subjected to the demagnetizing field correction. Using the tabulated demagnetization factors and the differential magnetic susceptibility of the samples, the values of the radial magnetometric demagnetization factor were obtained in the particular case of VSM880 magnetometer. It was found that the demagnetizing field correction keeps the saturation magnetization values unchanged, but instead the initial magnetic susceptibility of the magnetic fluid samples varies widely. The mean magnetic diameter, obtained through magnetogranulometry from the measured data, is higher than that obtained from the corrected ones and the variation rate increases with the magnetic particle volume fraction growth.

  9. Robust Magnetic Properties of a Sublimable Single-Molecule Magnet.

    Science.gov (United States)

    Kiefl, Evan; Mannini, Matteo; Bernot, Kevin; Yi, Xiaohui; Amato, Alex; Leviant, Tom; Magnani, Agnese; Prokscha, Thomas; Suter, Andreas; Sessoli, Roberta; Salman, Zaher

    2016-06-28

    The organization of single-molecule magnets (SMMs) on surfaces via thermal sublimation is a prerequisite for the development of future devices for spintronics exploiting the richness of properties offered by these magnetic molecules. However, a change in the SMM properties due to the interaction with specific surfaces is usually observed. Here we present a rare example of an SMM system that can be thermally sublimated on gold surfaces while maintaining its intact chemical structure and magnetic properties. Muon spin relaxation and ac susceptibility measurements are used to demonstrate that, unlike other SMMs, the magnetic properties of this system in thin films are very similar to those in the bulk, throughout the full volume of the film, including regions near the metal and vacuum interfaces. These results exhibit the robustness of chemical and magnetic properties of this complex and provide important clues for the development of nanostructures based on SMMs.

  10. Single Crystal Growth and Magnetic Properties of Ferromagnetic URhGe2

    International Nuclear Information System (INIS)

    Matsuda, T.D.; Haga, Y.; Tokiwa, Y.; Galatanu, A.; Yamamoto, E.; Okubo, T.; Onuki, Y.

    2003-01-01

    We have successfully grown a single crystal of uranium intermetallic compound URhGe 2 . The temperature dependence of electrical resistivity shows highly anisotropic behavior. Two anomalies, which correspond to the magnetic ordering temperatures, were observed in the resistivity, magnetic susceptibility and specific heat measurements at T M1 30 K and T M2 =25 K. The magnetic susceptibility also shows a large uniaxial anisotropy with a magnetic easy-axis along the [010] direction. (author)

  11. 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

  12. Extraction of remanent magnetization from magnetization vector inversions of airborne full tensor magnetic gradiometry data

    Science.gov (United States)

    Queitsch, M.; Schiffler, M.; Stolz, R.; Meyer, M.; Kukowski, N.

    2017-12-01

    Measurements of the Earth's magnetic field are one of the most used methods in geophysical exploration. The ambiguity of the method, especially during modeling and inversion of magnetic field data sets, is one of its biggest challenges. Additional directional information, e.g. gathered by gradiometer systems based on Superconducting Quantum Interference Devices (SQUIDs), will positively influence the inversion results and will thus lead to better subsurface magnetization models. This is especially beneficial, regarding the shape and direction of magnetized structures, especially when a significant remanent magnetization of the underlying sources is present. The possibility to separate induced and remanent contributions to the total magnetization may in future also open up advanced ways for geological interpretation of the data, e.g. a first estimation of diagenesis processes. In this study we present the results of airborne full tensor magnetic gradiometry (FTMG) surveys conducted over a dolerite intrusion in central Germany and the results of two magnetization vector inversions (MVI) of the FTMG and a conventional total field anomaly data set. A separation of the two main contributions of the acquired total magnetization will be compared with information of the rock magnetization measured on orientated rock samples. The FTMG inversion results show a much better agreement in direction and strength of both total and remanent magnetization compared to the inversion using only total field anomaly data. To enhance the separation process, the application of additional geophysical methods, i.e. frequency domain electromagnetics (FDEM), in order to gather spatial information of subsurface rock susceptibility will also be discussed. In this approach, we try to extract not only information on subsurface conductivity but also the induced magnetization. Using the total magnetization from the FTMG data and the induced magnetization from the FDEM data, the full separation of

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

    DEFF Research Database (Denmark)

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

    1997-01-01

    Magnetic liquids containing iron-oxide particles were investigated by magnetization and Mossbauer measurements. The particles were shown to be maghemite with a spontanious saturation magentization Ms = 320 kA m-1 at 200 K and a normalized high-field susceptibility x/M0 = 5.1x10-6 mkA-1, practically...

  14. NMR Spectroscopy Identifies Metabolites Translocated from Powdery Mildew Resistant Rootstocks to Susceptible Watermelon Scions.

    Science.gov (United States)

    Mahmud, Iqbal; Kousik, Chandrasekar; Hassell, Richard; Chowdhury, Kamal; Boroujerdi, Arezue F

    2015-09-16

    Powdery mildew (PM) disease causes significant loss in watermelon. Due to the unavailability of a commercial watermelon variety that is resistant to PM, grafting susceptible cultivars on wild resistant rootstocks is being explored as a short-term management strategy to combat this disease. Nuclear magnetic resonance-based metabolic profiles of susceptible and resistant rootstocks of watermelon and their corresponding susceptible scions (Mickey Lee) were compared to screen for potential metabolites related to PM resistance using multivariate principal component analysis. Significant score plot differences between the susceptible and resistant groups were revealed through Mahalanobis distance analysis. Significantly different spectral buckets and their corresponding metabolites (including choline, fumarate, 5-hydroxyindole-3-acetate, and melatonin) have been identified quantitatively using multivariate loading plots and verified by volcano plot analyses. The data suggest that these metabolites were translocated from the powdery mildew resistant rootstocks to their corresponding powdery mildew susceptible scions and can be related to PM disease resistance.

  15. Whole tissue AC susceptibility after superparamagnetic iron oxide contrast agent administration in a rat model

    Energy Technology Data Exchange (ETDEWEB)

    Lazaro, Francisco Jose [Departamento de Ciencia y Tecnologia de Materiales y Fluidos, Universidad de Zaragoza, 50018 Zaragoza (Spain) and Instituto de Nanociencia de Aragon, Universidad de Zaragoza, 50009 Zaragoza (Spain)]. E-mail: osoro@unizar.es; Gutierrez, Lucia [Departamento de Ciencia y Tecnologia de Materiales y Fluidos, Universidad de Zaragoza, 50018 Zaragoza (Spain); Rosa Abadia, Ana [Dept. Farmacologia y Fisiologia, Universidad de Zaragoza, 50013 Zaragoza (Spain); Soledad Romero, Maria [Dept. Medicina y Psiquiatria, Universidad de Zaragoza, 50009 Zaragoza (Spain); Lopez, Antonio [CNAM - Zaragoza, 50009 Zaragoza (Spain); Jesus Munoz, Maria [Dept. Farmacologia y Fisiologia, Universidad de Zaragoza, 50013 Zaragoza (Spain)

    2007-04-15

    A magnetic AC susceptibility characterisation of rat tissues after intravenous administration of superparamagnetic iron oxide (Endorem{sup (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.

  16. 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)

  17. India, Genomic diversity & Disease susceptibility

    Indian Academy of Sciences (India)

    Table of contents. India, Genomic diversity & Disease susceptibility · India, a paradise for Genetic Studies · Involved in earlier stages of Immune response protecting us from Diseases, Responsible for kidney and other transplant rejections Inherited from our parents · PowerPoint Presentation · Slide 5 · Slide 6 · Slide 7.

  18. Prion protein and scrapie susceptibility

    NARCIS (Netherlands)

    Smits, M.A.; Bossers, A.; Schreuder, B.E.C.

    1997-01-01

    This article presents briefly current views on the role of prion protein (PrP) in Transmissible Spongiform Encephalopathies or prion diseases and the effect of PrP polymoryhisms on the susceptibility to these diseases, with special emphasis on sheep scrapie. The PrP genotype of sheep apears to be a

  19. Magnetism, Nanosized Magnetic Materials

    Science.gov (United States)

    Miller, Joel S.; Drillon, Marc

    2002-01-01

    Magnetic behaviour, once thought to be mature, has gained a new momentum as it is being expanded by contributions from molecular chemistry, materials sciences to solid state physics. The spectrum spans molecule-based - organic, inorganic, and hybrid - compounds, metallic materials as well as their oxides forming, for example, thin films, nanoparticles, nanowires. New phenomena are explored that open promising perspectives for commercially applied "smart" materials. As a depository of contemporary knowledge on key topics related to magnetism, this open series of volumes provides a much-needed comprehensive overview of this growing interdisciplinary field. The topical reviews are written by the foremost scientists in the area, and the trends and recent advances are explained in a clear and detailed manner with a focus on the correlations between electronic structure and magnetic properties. The balance between theory and experiment within this series will guide advanced students and specialists in evaluating experimental observations and will serve as a basis for the design of new magnetic materials. This is a unique reference work, indispensable for everyone concerned with the phenomena of magnetism!

  20. Nonlinear control of magnetic signatures

    Science.gov (United States)

    Niemoczynski, Bogdan

    Magnetic properties of ferrite structures are known to cause fluctuations in Earth's magnetic field around the object. These fluctuations are known as the object's magnetic signature and are unique based on the object's geometry and material. It is a common practice to neutralize magnetic signatures periodically after certain time intervals, however there is a growing interest to develop real time degaussing systems for various applications. Development of real time degaussing system is a challenging problem because of magnetic hysteresis and difficulties in measurement or estimation of near-field flux data. The goal of this research is to develop a real time feedback control system that can be used to minimize magnetic signatures for ferrite structures. Experimental work on controlling the magnetic signature of a cylindrical steel shell structure with a magnetic disturbance provided evidence that the control process substantially increased the interior magnetic flux. This means near field estimation using interior sensor data is likely to be inaccurate. Follow up numerical work for rectangular and cylindrical cross sections investigated variations in shell wall flux density under a variety of ambient excitation and applied disturbances. Results showed magnetic disturbances could corrupt interior sensor data and magnetic shielding due to the shell walls makes the interior very sensitive to noise. The magnetic flux inside the shell wall showed little variation due to inner disturbances and its high base value makes it less susceptible to noise. This research proceeds to describe a nonlinear controller to use the shell wall data as an input. A nonlinear plant model of magnetics is developed using a constant tau to represent domain rotation lag and a gain function k to describe the magnetic hysteresis curve for the shell wall. The model is justified by producing hysteresis curves for multiple materials, matching experimental data using a particle swarm algorithm, and

  1. Anisotropic magnetism in field-structured composites

    International Nuclear Information System (INIS)

    Martin, James E.; Venturini, Eugene; Odinek, Judy; Anderson, Robert A.

    2000-01-01

    Magnetic field-structured composites (FSCs) are made by structuring magnetic particle suspensions in uniaxial or biaxial (e.g., rotating) magnetic fields, while polymerizing the suspending resin. A uniaxial field produces chainlike particle structures, and a biaxial field produces sheetlike particle structures. In either case, these anisotropic structures affect the measured magnetic hysteresis loops, with the magnetic remanence and susceptibility increased significantly along the axis of the structuring field, and decreased slightly orthogonal to the structuring field, relative to the unstructured particle composite. The coercivity is essentially unaffected by structuring. We present data for FSCs of magnetically soft particles, and demonstrate that the altered magnetism can be accounted for by considering the large local fields that occur in FSCs. FSCs of magnetically hard particles show unexpectedly large anisotropies in the remanence, and this is due to the local field effects in combination with the large crystalline anisotropy of this material. (c) 2000 The American Physical Society

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

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Vesali Naseh

    2012-12-01

    Full Text Available 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 thewetland (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 metalconcentrations 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 ofsamples 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.

  3. 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.

  4. 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.)

  5. Magnetic filtration process, magnetic filtering material, and methods of forming magnetic filtering material

    Science.gov (United States)

    Taboada-Serrano, Patricia; Tsouris, Constantino; Contescu, Cristian I; McFarlane, Joanna

    2013-10-08

    The present invention provides magnetically responsive activated carbon, and a method of forming magnetically responsive activated carbon. The method of forming magnetically responsive activated carbon typically includes providing activated carbon in a solution containing ions of ferrite forming elements, wherein at least one of the ferrite forming elements has an oxidation state of +3 and at least a second of the ferrite forming elements has an oxidation state of +2, and increasing pH of the solution to precipitate particles of ferrite that bond to the activated carbon, wherein the activated carbon having the ferrite particles bonded thereto have a positive magnetic susceptibility. The present invention also provides a method of filtering waste water using magnetic activated carbon.

  6. 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.

  7. Susceptible-infected-recovered and susceptible-exposed-infected models

    Energy Technology Data Exchange (ETDEWEB)

    Tome, Tania; De Oliveira, Mario J, E-mail: oliveira@if.usp.br [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970 Sao Paulo, Sao Paulo (Brazil)

    2011-03-04

    Two stochastic epidemic lattice models, the susceptible-infected-recovered and the susceptible-exposed-infected models, are studied on a Cayley tree of coordination number k. The spreading of the disease in the former is found to occur when the infection probability b is larger than b{sub c} = k/2(k - 1). In the latter, which is equivalent to a dynamic site percolation model, the spreading occurs when the infection probability p is greater than p{sub c} = 1/(k - 1). We set up and solve the time evolution equations for both models and determine the final and time-dependent properties, including the epidemic curve. We show that the two models are closely related by revealing that their relevant properties are exactly mapped into each other when p = b/[k - (k - 1)b]. These include the cluster size distribution and the density of individuals of each type, quantities that have been determined in closed forms.

  8. 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.

  9. Foundations of MRI phase imaging and processing for Quantitative Susceptibility Mapping (QSM)

    Energy Technology Data Exchange (ETDEWEB)

    Schweser, Ferdinand [New York State Univ., Buffalo, NY (United States). Buffalo Neuroimaging Analysis Center; New York State Univ., Buffalo, NY (United States). MRI Clinical and Translational Research Center; Deistung, Andreas [Jena Univ. (Germany). Medical Physics Group; Reichenbach, Juergen R. [Jena Univ. (Germany). Medical Physics Group; Jena Univ. (Germany). Michael Stifel Center for Data-driven and Simulation Science Jena

    2016-05-01

    Quantitative Susceptibility Mapping (QSM) is a novel MRI based technique that relies on estimates of the magnetic field distribution in the tissue under examination. Several sophisticated data processing steps are required to extract the magnetic field distribution from raw MRI phase measurements. The objective of this review article is to provide a general overview and to discuss several underlying assumptions and limitations of the pre-processing steps that need to be applied to MRI phase data before the final field-to-source inversion can be performed. Beginning with the fundamental relation between MRI signal and tissue magnetic susceptibility this review covers the reconstruction of magnetic field maps from multi-channel phase images, background field correction, and provides an overview of state of the art QSM solution strategies.

  10. Dynamic susceptibility study of YFe{sub x}Al{sub 12-x} (4 {<=} x {<=} 5)

    Energy Technology Data Exchange (ETDEWEB)

    Serio, S. [Quimica/CFMC, Instituto Tecnologico e Nuclear, 2686-953 Sacavem (Portugal)], E-mail: susana.serio@fct.unl.pt; Pereira, L.C.J. [Quimica/CFMC, Instituto Tecnologico e Nuclear, 2686-953 Sacavem (Portugal); Cruz, M.M.; Godinho, M. [Dept. Fisica/CFMC, FCUL, Campo Grande ed.C8, 1749-016 Lisboa (Portugal); Waerenborgh, J.C. [Quimica/CFMC, Instituto Tecnologico e Nuclear, 2686-953 Sacavem (Portugal)

    2009-05-27

    Linear and nonlinear susceptibility measurements have been performed in YFe{sub x}Al{sub 12-x} (x = 4, 4.7 and 5) intermetallic compounds. This study confirms that long-range order only takes place below the transition temperature values, T{sub c}, previously detected by magnetization and Moessbauer data. Antiferromagnetic interactions are dominant for YFe{sub 4}Al{sub 8}, however the enhancement of the magnetic susceptibility with iron content evidences that a ferromagnetic-type ordering with increasing strength develops with the replacement of aluminum by iron atoms. The coexistence of competing antiferromagnetic and ferromagnetic interactions gives rise to magnetic frustration, leading to a complex magnetic behaviour dependent on applied field and temperature. For all compositions, including the ordered YFe{sub 4}Al{sub 8}, there is evidence of uncorrelated iron-rich nanoclusters with short-range ferromagnetic-like order above T{sub c}.

  11. 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.

  12. 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

  13. Magnetic Levitation.

    Science.gov (United States)

    Rossing, Thomas D.; Hull, John R.

    1991-01-01

    Discusses the principles of magnetic levitation presented in the physics classroom and applied to transportation systems. Topics discussed include three classroom demonstrations to illustrate magnetic levitation, the concept of eddy currents, lift and drag forces on a moving magnet, magnetic levitation vehicles, levitation with permanent magnets…

  14. Magnetic properties

    Indian Academy of Sciences (India)

    Unknown

    netic moments of the particles, i.e. Zeeman energy, µH, where µ is the magnetic moment of the particle and H .... the domain magnetization of particle. Here, we have assumed a log-normal distribution function, P(D), for ... Effect of texturing field on a magnetically textured fluid magnetization for (a) (HT || H) and (b) (HT ⊥ H) ...

  15. Magnetic Spinner

    Science.gov (United States)

    Ouseph, P. J.

    2006-01-01

    A science toy sometimes called the "magnetic spinner" is an interesting class demonstration to illustrate the principles of magnetic levitation. It can also be used to demonstrate Faraday's law and a horizontally suspended physical pendulum. The levitated part contains two circular magnets encased in a plastic housing. Each magnet stays…

  16. Topological susceptibility from the overlap

    DEFF Research Database (Denmark)

    Del Debbio, Luigi; Pica, Claudio

    2003-01-01

    The chiral symmetry at finite lattice spacing of Ginsparg-Wilson fermionic actions constrains the renormalization of the lattice operators; in particular, the topological susceptibility does not require any renormalization, when using a fermionic estimator to define the topological charge....... Therefore, the overlap formalism appears as an appealing candidate to study the continuum limit of the topological susceptibility while keeping the systematic errors under theoretical control. We present results for the SU(3) pure gauge theory using the index of the overlap Dirac operator to study...... the topology of the gauge configurations. The topological charge is obtained from the zero modes of the overlap and using a new algorithm for the spectral flow analysis. A detailed comparison with cooling techniques is presented. Particular care is taken in assessing the systematic errors. Relatively high...

  17. Reducing Susceptibility to Courtesy Stigma.

    Science.gov (United States)

    Bachleda, Catherine L; El Menzhi, Leila

    2018-06-01

    In light of the chronic shortage of health professionals willing to care for HIV/AIDS patients, and rising epidemics in many Muslim countries, this qualitative study examined susceptibility and resistance to courtesy stigma as experienced by nurses, doctors, and social workers in Morocco. Forty-nine in-depth interviews provided rich insights into the process of courtesy stigma and how it is managed, within the context of interactions with Islam, interactions within the workplace (patients, other health professionals), and interactions outside the workplace (the general public, friends, and family). Theoretically, the findings extend understanding of courtesy stigma and the dirty work literature. The findings also offer practical suggestions for the development of culturally appropriate strategies to reduce susceptibility to courtesy stigmatization. This study represents the first to explore courtesy stigma as a process experienced by health professionals providing HIV/AIDS care in an Islamic country.

  18. Dysprosium Acetylacetonato Single-Molecule Magnet Encapsulated in Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Ryo Nakanishi

    2016-12-01

    Full Text Available Dy single-molecule magnets (SMMs, which have several potential uses in a variety of applications, such as quantum computing, were encapsulated in multi-walled carbon nanotubes (MWCNTs by using a capillary method. Encapsulation was confirmed by using transmission electron microscopy (TEM. In alternating current magnetic measurements, the magnetic susceptibilities of the Dy acetylacetonato complexes showed clear frequency dependence even inside the MWCNTs, meaning that this hybrid can be used as magnetic materials in devices.

  19. Genetic susceptibility to lead poisoning.

    OpenAIRE

    Onalaja, A O; Claudio, L

    2000-01-01

    Major strides have been taken in the regulation of lead intoxication in the general population, but studies using genetic markers of susceptibility to environmental toxicants raise the question of whether genes can make certain individuals more vulnerable to environmental toxins such as lead. At least three polymorphic genes have been identified that potentially can influence the bioaccumulation and toxicokinetics of lead in humans. The first gene to be discussed in this review is the gene co...

  20. Antimycotics susceptibility testing of dermatophytes

    Directory of Open Access Journals (Sweden)

    Arsić-Arsenijević Valentina

    2010-01-01

    Full Text Available Dermatophytes are moulds that produce infections of the skin, hair and nails of humans and animals. The most common forms among these infections are onychomycosis and tinea pedis affecting 20% of world population. These infections are usually chronic. The treatment of dermatophytoses tends to be prolonged partly because available treatments are not very effective. Antifungal drug consumption and public health expenditure are high worldwide, as well as in Serbia. For adequate therapy, it is necessary to prove infection by isolation of dermatophytes and to test the antifungal susceptibility of isolates. Susceptibility testing is important for the resistance monitoring, epidemiological research and to compare in vitro activities of new antifungal agents. The diffusion and dilution methods of susceptibility tests are used, and technical issues of importance for the proper performance and interpretation of test results are published in the document E.DEF 9.1 (EUCAST and M38-A2 (CLSI. The aim of our paper is to promptly inform the public about technical achievements in this area, as well as the new organization of laboratory for medical mycology in our country. The formation of laboratory networks coordinated by the National Reference Laboratory for the cause of mycosis need to enable interlaboratory studies and further standardization of methods for antifungal susceptibility testing of dermatophytes, reproducibility of tests and clinical correlation monitoring (MIK values and clinical outcome of dermatophytosis. The importance of the new organization is expected efficient improvement in the dermatophytosis therapy at home, better quality of patient's life and the reduction of the cost of treatment.

  1. Transgenic mice susceptible to poliovirus.

    OpenAIRE

    Koike, S; Taya, C; Kurata, T; Abe, S; Ise, I; Yonekawa, H; Nomoto, A

    1991-01-01

    Poliovirus-sensitive transgenic mice were produced by introducing the human gene encoding cellular receptors for poliovirus into the mouse genome. Expression of the receptor mRNAs in tissues of the transgenic mice was analyzed by using RNA blot hybridization and the polymerase chain reaction. The human gene is expressed in many tissues of the transgenic mice just as in tissues of humans. The transgenic mice are susceptible to all three poliovirus serotypes, and the mice inoculated with poliov...

  2. Vector susceptibility to African trypanosomes.

    Science.gov (United States)

    Le Ray, D

    1989-01-01

    Susceptibility of tsetse fly to trypanosome depends on two distinct barriers controlling respectively colonization of midgut and, migration to salivary glands. Those barriers are modulated by barely known factors, pertaining to the physiological status of the fly as well as to cytoplasmic and nuclear inheritance. Quantification of colonization (p) and migration (m) rates provides a way to calculate intrinsic vectorial capacity (IVC) as a product IVC = p x m, and to undergo comparative analysis of underlying factors.

  3. Process and apparatus for preparing textured crystalline materials using anisotropy in the paramagnetic susceptibility

    Science.gov (United States)

    Holloway, A.

    1992-01-07

    The present invention discloses a process and apparatus for forming textures in materials. The process comprises heating a material having an anisotropy in the paramagnetic or diamagnetic susceptibility within a magnetic field. The material is heated to a temperature approaching its melting point while a magnetic field of at least 10[sup 4]Oe is simultaneously applied. The process and apparatus produce highly textured bulk and elongated materials with high current densities below critical superconducting temperatures. 6 figs.

  4. 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

  5. Antibiotic susceptibility of Atopobium vaginae

    Directory of Open Access Journals (Sweden)

    Verschraegen Gerda

    2006-03-01

    Full Text Available Abstract Background Previous studies have indicated that a recently described anaerobic bacterium, Atopobium vaginae is associated with bacterial vaginosis (BV. Thus far the four isolates of this fastidious micro-organism were found to be highly resistant to metronidazole and susceptible for clindamycin, two antibiotics preferred for the treatment of BV. Methods Nine strains of Atopobium vaginae, four strains of Gardnerella vaginalis, two strains of Lactobacillus iners and one strain each of Bifidobacterium breve, B. longum, L. crispatus, L. gasseri and L. jensenii were tested against 15 antimicrobial agents using the Etest. Results All nine strains of A. vaginae were highly resistant to nalidixic acid and colistin while being inhibited by low concentrations of clindamycin (range: G. vaginalis strains were also susceptible for clindamycin ( 256 μg/ml but susceptible to clindamycin (0.023 – 0.125 μg/ml. Conclusion Clindamycin has higher activity against G. vaginalis and A. vaginae than metronidazole, but not all A. vaginae isolates are metronidazole resistant, as seemed to be a straightforward conclusion from previous studies on a more limited number of strains.

  6. Defining susceptibility of broiler chicks to colibacillosis

    NARCIS (Netherlands)

    Ask, B.; Waaij, van der E.H.; Eck, van J.H.H.; Arendonk, van J.A.M.; Stegeman, J.A.

    2006-01-01

    This study aimed to define the susceptibility of broilers to colibacillosis through quantification of clinical responses and to examine the relationship between susceptibility and growth retardation. A challenge experiment was carried out twice. In each trial, 192 chicks were challenged

  7. Antimicrobial Susceptibility Patterns Of Salmonella Species In ...

    African Journals Online (AJOL)

    % susceptible to cefepime and carbapenem, 91% to azithromycin, 82.1% to cefixime and 73% to quinolones. Also susceptibility to chloramphenicol, erythromycin, streptomycin, ampicillin, gentamicin, co-trimoxazole, augmentin and amikacin ...

  8. Study of Static Magnetic Properties of Transformer Oil Based Magnetic Fluids for Various Technical Applications Using Demagnetizing Field Correction

    OpenAIRE

    Oana Maria Marinica

    2017-01-01

    Static magnetization data of eight transformer oil based magnetic fluid samples, with saturation magnetization ranging in a large interval from 9 kA/m to 90 kA/m, have been subjected to the demagnetizing field correction. Using the tabulated demagnetization factors and the differential magnetic susceptibility of the samples, the values of the radial magnetometric demagnetization factor were obtained in the particular case of VSM880 magnetometer. It was found that the demagnetizing field corre...

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

    Directory of Open Access Journals (Sweden)

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

    2009-01-01

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

  10. Correction of susceptibility-induced GRE phase shift for accurate PRFS thermometry proximal to cryoablation iceball.

    Science.gov (United States)

    Kickhefel, Antje; Weiss, Clifford; Roland, Joerg; Gross, Patrick; Schick, Fritz; Salomir, Rares

    2012-02-01

    The susceptibility contrast between frozen and unfrozen tissue disturbs the local magnetic field in the proximity of the ice-ball during cryotherapy. This effect should be corrected for in real time to allow PRFS-based monitoring of near-zero temperatures during intervention. Susceptibility artifacts were corrected post-processing, using a rapid numerical algorithm. The difference in bulk magnetic susceptibility between frozen and non-frozen tissue was approximated to be uniform over the ice-ball volume and was determined from the isothermal principle applied to the phase-transition frontier of compartments. Subsequently, the magnetic perturbation field was calculated rapidly in 3D using a Fourier-convolution. Experimental studies were performed for two scenarios: tissue defrosting in a water bath and induction of an ice-ball by a MR-compatible cryogenic probe. The susceptibility artifacts yielded PRFS temperature errors as high as 10-12°C proximal to the ice-ball, positive or negative depending on the relative orientation of the position vector from the B(o) direction. These effects were fully corrected for to within the noise range. The susceptibility-corrected PRFS temperature values were consistent with the phase-transition isothermal condition, irrespective of the local orientation of the position vector. By implementing on-line the post processing algorithm, PRFS MRT may be used as a safety tool for non-invasive and accurate monitoring of near-zero temperatures during MR-guided clinical cryotherapy.

  11. A role for susceptibility weighted imaging in progressive multifocal leukoencephalopathy

    LENUS (Irish Health Repository)

    Yap, SM

    2017-04-01

    We report a radiologic finding on magnetic resonance imaging (MRI) of the brain of two cases of progressive multifocal leukoencephalopathy (PML) of hypointense signal of subcortical U-fibres on susceptibility weighted (SW) sequence. The first case is a 50-year-old man recently treated with chemotherapy including rituximab for non-Hodgkin\\'s lymphoma. The second case is a 64-year-old woman with human immunodeficiency virus (HIV) infection. Iron deposition is a likely causative factor. We propose that SWI may be especially useful in the assessment of indeterminate cases to reduce the likelihood of a missed diagnosis of PML

  12. Demagnetization treatment of remanent composite microspheres studied by alternating current susceptibility measurements.

    Science.gov (United States)

    van Berkum, Susanne; Erné, Ben H

    2013-09-04

    The magnetic remanence of silica microspheres with a low concentration of embedded cobalt ferrite nanoparticles is studied after demagnetization and remagnetization treatments. When the microspheres are dispersed in a liquid, alternating current (AC) magnetic susceptibility spectra reveal a constant characteristic frequency, corresponding to the rotational diffusion of the microparticles; this depends only on particle size and liquid viscosity, making the particles suitable as a rheological probe and indicating that interactions between the microspheres are weak. On the macroscopic scale, a sample with the dry microparticles is magnetically remanent after treatment in a saturating field, and after a demagnetization treatment, the remanence goes down to zero. The AC susceptibility of a liquid dispersion, however, characterizes the remanence on the scale of the individual microparticles, which does not become zero after demagnetization. The reason is that an individual microparticle contains only a relatively small number of magnetic units, so that even if they can be reoriented magnetically at random, the average vector sum of the nanoparticle dipoles is not negligible on the scale of the microparticle. In contrast, on the macroscopic scale, the demagnetization procedure randomizes the orientations of a macroscopic number of magnetic units, resulting in a remanent magnetization that is negligible compared to the saturation magnetization of the entire sample.

  13. A.c. susceptibility study of CaCl2 doped copper–zinc ferrite system

    Indian Academy of Sciences (India)

    Unknown

    The Curie temperature measurement was carried out by a.c. susceptibility and modified Loria-Sinha technique at lower humidity in summer (40% relative humidity) and at higher humidity in rainy season (93% relative humi- dity). It is observed that magnetic property like suscepti- bility is not affected by relative humidity.

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

    Czech Academy of Sciences Publication Activity Database

    Janů, Zdeněk; Švindrych, Zdeněk; Truněček, O.; Kúš, P.; Plecenik, A.

    2011-01-01

    Roč. 471, 23-24 (2011), s. 1647-1650 ISSN 0921-4534 R&D Projects: GA MŠk(CZ) ME10069 Institutional research plan: CEZ:AV0Z10100520 Keywords : intermediate state * mixed state * AC susceptibility Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.014, year: 2011

  15. Landslide temporal analysis and susceptibility assessment as bases for landslide mitigation, Machu Picchu, Peru

    Czech Academy of Sciences Publication Activity Database

    Klimeš, Jan

    2013-01-01

    Roč. 70, č. 2 (2013), s. 913-925 ISSN 1866-6280 Institutional research plan: CEZ:AV0Z30460519 Keywords : landslide inventory * landslide frequency * susceptibility map Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 1.572, year: 2013

  16. Bjork-Shiley convexoconcave valves: Susceptibility artifacts at brain MR imaging and mechanical valve fractures

    NARCIS (Netherlands)

    van Gorp, Maarten J.; van der Graaf, Yolanda; de Mol, Bas A. J. M.; Bakker, Chris J. G.; Witkamp, Theo D.; Ramos, Lino M. P.; Mali, Willem P. T. M.

    2004-01-01

    PURPOSE: To assess the relationship between heart valve history and susceptibility artifacts at magnetic resonance (MR) imaging of the brain in patients with Bjork-Shiley convexoconcave (BSCC) valves. MATERIALS AND METHODS: MR images of the brain were obtained in 58 patients with prosthetic heart

  17. Susceptibility weighted imaging: differentiating between calcification and hemosiderin.

    Science.gov (United States)

    Barbosa, Jeam Haroldo Oliveira; Santos, Antonio Carlos; Salmon, Carlos Ernesto Garrido

    2015-01-01

    To present a detailed explanation on the processing of magnetic susceptibility weighted imaging (SWI), demonstrating the effects of echo time and sensitive mask on the differentiation between calcification and hemosiderin. Computed tomography and magnetic resonance (magnitude and phase) images of six patients (age range 41- 54 years; four men) were retrospectively selected. The SWI images processing was performed using the Matlab's own routine. Four out of the six patients showed calcifications at computed tomography images and their SWI images demonstrated hyperintense signal at the calcification regions. The other patients did not show any calcifications at computed tomography, and SWI revealed the presence of hemosiderin deposits with hypointense signal. The selection of echo time and of the mask may change all the information on SWI images, and compromise the diagnostic reliability. Amongst the possible masks, the authors highlight that the sigmoid mask allows for contrasting calcifications and hemosiderin on a single SWI image.

  18. Susceptibility weighted imaging: differentiating between calcification and hemosiderin

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Jeam Haroldo Oliveira; Salmon, Carlos Ernesto Garrido, E-mail: jeamharoldo@hotmail.com [Universidade de Sao Paulo (FFCLRP/USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras; Santos, Antonio Carlos [Universidade de Sao Paulo (FMRP/USP), Ribeirao Preto, SP (Brazil). Faculdade de Medicina

    2015-03-15

    Objective: to present a detailed explanation on the processing of magnetic susceptibility weighted imaging (SWI), demonstrating the effects of echo time and sensitive mask on the differentiation between calcification and hemosiderin. Materials and methods: computed tomography and magnetic resonance (magnitude and phase) images of six patients (age range 41-54 years; four men) were retrospectively selected. The SWI images processing was performed using the Matlab's own routine. Results: four out of the six patients showed calcifications at computed tomography images and their SWI images demonstrated hyperintense signal at the calcification regions. The other patients did not show any calcifications at computed tomography, and SWI revealed the presence of hemosiderin deposits with hypointense signal. Conclusion: the selection of echo time and of the mask may change all the information on SWI images, and compromise the diagnostic reliability. Amongst the possible masks, the authors highlight that the sigmoid mask allows for contrasting calcifications and hemosiderin on a single SWI image. (author)

  19. Ceftriaxone susceptibility of oxacillin-susceptible Staphylococcus aureus from patients with prosthetic joint infection.

    Science.gov (United States)

    Greenwood-Quaintance, Kerryl E; Kohner, Peggy; Osmon, Douglas R; Virk, Abinash; Patel, Robin

    2015-06-01

    Ceftriaxone is used to treat oxacillin-susceptible S. aureus (OSSA) prosthetic joint infection (PJI). Susceptibility of ceftriaxone against OSSA has been questioned. Ceftriaxone susceptibility was determined against 100 PJI OSSA isolates. Ceftriaxone MIC90/MIC50 were 8/4 and 4/3μg/mL by broth microdilution and Etest, respectively. Ceftriaxone susceptibility is inferable by oxacillin susceptibility. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Preliminary magnetic studies of lagoon and stream sediments from Chascomús Area (Argentina)—magnetic parameters as indicators of heavy metal pollution and some results of using an experimental method to separate magnetic phases

    Science.gov (United States)

    Chaparro, Marcos A. E.; Lirio, Juan M.; Nuñez, Héctor; Gogorza, Claudia S. G.; Sinito, Ana M.

    2005-11-01

    Magnetic properties of lagoon and stream sediments from Chascomús area (Buenos Aires Province) and the relevance of various magnetic parameters as giving pollution status are studied in the present work. This work is focussed on magnetic parameters, such as concentration-dependent (magnetic susceptibility, saturation anhysteric and isothermal remanent magnetisation) and feature-dependent parameters (S-ratio, coercivity of remanence, anhysteric susceptibility/magnetic susceptibility-ratio), as pollution indicators. Firstly and most importantly, different magnetic parameters and chemical measurements were correlated in order to investigate their goodness, obtaining the best results for feature-dependent magnetic parameters. Coercivity of remanence correlate very well with chemical variables, showing correlations at high level of significance up to 0.9094, and the anhysteric susceptibility/magnetic susceptibility-ratio also shows very good correlations (up to 0.8376). Some results and advantages of using a new experimental method in order to discriminate hard and soft magnetic phases are also shown. This method uses alternately backfield isothermal remanent magnetisation and alternating field demagnetisation. From the experimental separation, the presence of hard magnetic phases in some samples was confirmed.

  1. 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.

  2. Magnetic Fields

    OpenAIRE

    Schöller, Markus; Hubrig, Swetlana

    2015-01-01

    In this chapter, we give a brief introduction into the use of the Zeeman effect in astronomy and the general detection of magnetic fields in stars, concentrating on the use of FORS2 for longitudinal magnetic field measurements.

  3. Magnetic anomaly in superconducting TmRh4B4

    International Nuclear Information System (INIS)

    Smith, J.L.; Huang, C.Y.; Tsou, J.J.; Ho, J.C.

    1978-01-01

    The magnetic and superconducting properties of TmRh 4 B 4 (which becomes superconducting at 9.6 K) by means of ac and dc magnetic susceptibility and specific heat measurements are investigated. At 10.7 K, an ac susceptibility peak similar to those found in spin glasses has been observed. In addition, a pronounced specific heat peak has been observed at 11.4 K. The susceptibility peak is essentially unaffected by substitution of 1% Lu or Er for the Tm, but it diminishes when much larger amounts of Er are substituted. The physical origin of this anomalous peak will be discussed

  4. Superconducting Magnets

    CERN Multimedia

    CERN. Geneva

    2008-01-01

    Starting from the beam requirements for accelerator magnets, we will outline the main issues and the physical limitations for producing strong and pure magnetic fields with superconductors. The seminar will mainly focus on the magnets for the accelerator, and give some hints on the magnets for the experiments. Prerequisite knowledge: Basic knowledge of Maxwell equations, and linear optics for particle accelerators (FODO cell, beta functions).

  5. Magnetic Nanostructures

    OpenAIRE

    Bennemann, K. H.

    2010-01-01

    Characteristic results of magnetism in small particles and thin films are presented. As a consequence of the reduced atomic coordination in small clusters and thin films the electronic states and density of states modify. Thus magnetic moments and magnetization are affected. In tunnel junctions interplay of magnetism, spin currents and superconductivity are of particular interest. Results are given for single transition metal clusters, cluster ensembles, thin films and tunnel systems. Interes...

  6. Magnetic strings

    International Nuclear Information System (INIS)

    Chaves, Max

    2006-01-01

    The conception of the magnetic string is presented as an infinitely thin bundle of magnetic flux lines. The magnetic strings are surrounded by a film of current that rotates around them, and are a solution of Maxwell's equations. The magnetic potential contains a line singularity, and its stability can be established topologically. A few comments are added on the possibility that they may exist at a cosmological scale as relics of the Big Bang. (author) [es

  7. Magnetic Materials

    Science.gov (United States)

    Spaldin, Nicola A.

    2003-04-01

    Magnetic materials are the foundation of multi-billion dollar industries and the focus of intensive research across many disciplines. This book covers the fundamentals, basic theories and applications of magnetism and conventional magnetic materials. Based on a lecture course given by Nicola Spaldin in the Materials Department at University of California, Santa Barbara, the book is ideal for a one- semester course in magnetic materials. It contains numerous homework problems and solutions.

  8. 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.)

  9. Amorphous magnetism

    International Nuclear Information System (INIS)

    Rechenberg, H.R.

    1984-01-01

    The consequences of disorder on magnetic properties of solids are examined. In this context the word 'disorder' is not synonimous of structural amorphicity; chemical disorder can be achieved e.g. by randomly diffusing magnetic atoms on a nonmagnetic crystalline lattice. The name Amorphous Magnetism must be taken in a broad sense. (Author) [pt

  10. Superconducting magnets

    International Nuclear Information System (INIS)

    1994-08-01

    This report discusses the following topics on superconducting magnets: D19B and -C: The next steps for a record-setting magnet; D20: The push beyond 10 T: Beyond D20: Speculations on the 16-T regime; other advanced magnets for accelerators; spinoff applications; APC materials development; cable and cabling-machine development; and high-T c superconductor at low temperature

  11. Magnetic Reconnection

    NARCIS (Netherlands)

    Schep, T. J.

    1994-01-01

    This lecture deals with the concept of magnetic field lines and with the conservation of magnetic flux. In high temperature fusion devices like tokamaks flux conservation can be violated and reconnection can occur at closed magnetic field lines. Reconnection processes lead to changes in the global

  12. Theoretical study of the dynamic magnetic response of ferrofluid to static and alternating magnetic fields

    International Nuclear Information System (INIS)

    Batrudinov, Timur M.; Ambarov, Alexander V.; Elfimova, Ekaterina A.; Zverev, Vladimir S.; Ivanov, Alexey O.

    2017-01-01

    The dynamic magnetic response of ferrofluid in a static uniform external magnetic field to a weak, linear polarized, alternating magnetic field is investigated theoretically. The ferrofluid is modeled as a system of dipolar hard spheres, suspended in a long cylindrical tube whose long axis is parallel to the direction of the static and alternating magnetic fields. The theory is based on the Fokker-Planck-Brown equation formulated for the case when the both static and alternating magnetic fields are applied. The solution of the Fokker-Planck-Brown equation describing the orientational probability density of a randomly chosen dipolar particle is expressed as a series in terms of the spherical Legendre polynomials. The obtained analytical expression connecting three neighboring coefficients of the series makes possible to determine the probability density with any order of accuracy in terms of Legendre polynomials. The analytical formula for the probability density truncated at the first Legendre polynomial is evaluated and used for the calculation of the magnetization and dynamic susceptibility spectra. In the absence of the static magnetic field the presented theory gives the correct single-particle Debye-theory result, which is the exact solution of the Fokker-Planck-Brown equation for the case of applied weak alternating magnetic field. The influence of the static magnetic field on the dynamic susceptibility is analyzed in terms of the low-frequency behavior of the real part and the position of the peak in the imaginary part. - Highlights: • The dynamic magnetic response of ferrofluid is investigated theoretically. • The static and alternating magnetic fields are applied along the Oz-axis. • Theory is based on the Fokker-Planck-Brown equation (FPBe). • The solution of FPBe is expressed as a series in terms of the Legendre polynomials. • The influence of static magnetic field on susceptibility spectra is analyzed.

  13. 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.

  14. 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

  15. MAGNETIC PROPERTIES OF THE SPINEL COMPOUND Cu1.30Cr1.30Zr0.70Se4

    Directory of Open Access Journals (Sweden)

    K BELAKROUM

    2009-12-01

    antiferromagnetic interactions due to the substitution of magnetic Cr for Zr atom, on the B sites forming a network of linked tetrahedral. The magnetization in field-cooled (FC and zero-fieldcooled (ZFC are observed with irreversibility in T≤ Tf, the overage Curie temperature, the effective magnetic moment and the temperature range, for which magnetic susceptibility can be regarded as linear are given.

  16. Terbium induced glassy magnetism in La,Ca-based cobaltites

    Czech Academy of Sciences Publication Activity Database

    Maryško, Miroslav; Hejtmánek, Jiří; Jirák, Zdeněk; Kaman, Ondřej; Knížek, Karel

    2014-01-01

    Roč. 115, č. 17 (2014), "17E103 -1"-"17E103 -3" ISSN 0021-8979 R&D Projects: GA ČR(CZ) GAP204/11/0713 Institutional support: RVO:68378271 Keywords : terbium * cobalt * magnetic susceptibilities Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.183, year: 2014

  17. Synthesis, structure and magnetic properties of the polyoxovanadate ...

    Indian Academy of Sciences (India)

    The magnetic susceptibility studies indicate that the interactions between the V centres in I are predominantly antiferromagnetic in nature and the compound shows highly frustrated behaviour. The magnetic properties are compared to the theoretical calculations based on the Heisenberg model, in addition to correlating to ...

  18. Structural and magnetic properties of zinc- and aluminum ...

    Indian Academy of Sciences (India)

    a decrease in ferrimagnetic behaviour. Keywords. Ferrite; co-precipitation; magnetization; AC susceptibility. PACS Nos 78.67.Bf; 01.30.-y; 85.70.Ge. 1. Introduction. The method of preparation plays a very important role with regard to the chemical, structural and magnetic properties of spinel ferrite [1]. Ferrites are commonly ...

  19. Magnetic phase transitions in TbNi(Al,In) compounds

    Czech Academy of Sciences Publication Activity Database

    Klicpera, M.; Javorský, P.; Šantavá, Eva

    2010-01-01

    Roč. 118, č. 5 (2010), s. 881-883 ISSN 0587-4246 Institutional research plan: CEZ:AV0Z10100520 Keywords : AC susceptibility * magnetic ordering Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.467, year: 2010 http://przyrbwn.icm.edu.pl/APP/PDF/118/a118z5p068.pdf

  20. Genetic susceptibility to environmental toxicants

    DEFF Research Database (Denmark)

    2001-01-01

    of their meaning. A potential for inadvertently raising concerns over the effect of chemicals in experimental animals or man, or even the intentional misrepresentation of results to suggest chemicals are “playing” with our genes is enormous. History has shown that some individuals and groups in society are willing......The toxicological challenges to the chemical industry have in recent years been greatly affected by the rapid innovation and development of analytical, molecular and genetic technologies. ECETOC recognises the importance of developing the technical and intellectual skill bases in academia...... and industrial based laboratories to meet the rapid development of the science base of toxicology. As the technology to determine genetic susceptibility develops, so scientist will be able to describe altered gene expression provoked by chemicals long before they are able to offer valid interpretations...

  1. Magnetic properties and the effect of non-magnetic impurities in the quasi-2D quantum magnet

    Science.gov (United States)

    Khuntia, P.; Dey, T.; Mahajan, A. V.

    2016-09-01

    We present synthesis, x-ray diffraction, magnetisation and specific heat studies on the quasi-two-dimensional (2D) S = 1/2 antiferromagnet (CuCl)LaNb2O7 and its doping analogues (Cu1-x Zn x Cl)LaNb2O7 (0 ≤ x ≤ 0.05), (Cu0.95Mg0.05Cl)LaNb2O7, and (CuCl)La1-y Ba y Nb2O7 (0 ≤ y ≤ 0.10). The magnetic susceptibility and specific heat of the parent compound and its isovalent or hetereovalent counterparts do not display any signature of magnetic ordering down to 1.8 K. The parent compound and its doping variants exhibit spin-singlet behaviour with a finite gap in the spin excitation spectrum due to dimerisation of the dominant intradimer interactions as evidenced from our magnetic susceptibility and specific heat data. The systematic increase of magnetic susceptibility at low temperature with non-magnetic Zn2+ and Mg2+ (S = 0) substitution at the Cu2+ site reflect that impurities induce local moments around the non-magnetic sites. While heterovalent Ba2+ substitution at the La3+ site do not result in mobile holes but rather give rise to a Curie term in the susceptibility due to localisation. The low value of spin S = 1/2, and absence of long range ordering or spin freezing, and the presence of competing exchange interactions hold special significance in hosting novel magnetic properties in this class of quasi-2D quantum material.

  2. Using magnetic birefringence to determine the molecular arrangement of supramolecular nanostructures

    International Nuclear Information System (INIS)

    Gielen, Jeroen C; Shklyarevskiy, Igor O; Christianen, Peter C M; Maan, J C; Schenning, Albertus P H J

    2009-01-01

    Supramolecular aggregates can be aligned in solution using a magnetic field. Because of the optical anisotropy of the molecular building blocks, the alignment results in an anisotropic refractive index of the solution parallel and perpendicular to the magnetic field. We present a model for calculating the magnetic birefringence, using solely the magnetic susceptibilities and optical polarizabilities of the molecules, for any molecular arrangement. We demonstrate that magnetic birefringence is a very sensitive tool for determining the molecular organization within supramolecular aggregates.

  3. 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

  4. Magnetism in californium

    International Nuclear Information System (INIS)

    Moore, J.R.

    1988-03-01

    A SQUID-based magnetic susceptometer has been constructed for studying small radioactive samples at temperatures below 350 K and in magnetic fields up to 50 kilogauss. The device has been used to study californium (element 98) in a number of solid-state forms: the dhcp metal, several oxides (Cf 2 O 3 in both the bcc and monoclinic structures, Cf 7 O 12 , CfO 2 and BaCfO 3 ), several monopnictides (CfN, CfAs and CfSb) and the trichloride (in both the hexagonal and orthorhombic structures). All of these materials were studied in polycrystalline form, and hexagonal CfCl 3 was studied in single-crystal form as well. The susceptometer has the sensitivity to measure samples containing less than 10 micrograms of californium. The magnetic susceptibilities of all of the californium materials at temperatures above about 100 K are described well by the Curie-Weiss relationship. This behavior is consistent with the assumption that the magnetic 5f electrons are localized and that the paramagnetic behavior can be interpreted in terms of the properties of the free ion. The measured values of the effective paramagnetic moment, μ/sub eff/, for all the californium materials that were studied are reasonably consistent with theoretical values based on intermediate coupling models. All of the californium materials showed some indications of cooperative magnetic effects. The dhcp metal was observed to order ferromagnetically at 52 K, and all of the californium compounds studied showed signs of antiferromagnetic ordering, mostly at temperatures below 25 K. 91 refs., 50 figs., 19 tabs

  5. Magnetism in layered Ruthenates

    International Nuclear Information System (INIS)

    Steffens, Paul C.

    2008-01-01

    In this thesis, the magnetism of the layered Ruthenates has been studied by means of different neutron scattering techniques. Magnetic correlations in the single-layer Ruthenates of the series Ca 2-x Sr x RuO 4 have been investigated as function of Sr-concentration (x=0.2 and 0.62), temperature and magnetic field. These inelastic neutron scattering studies demonstrate the coexistence of ferromagnetic paramagnon scattering with antiferromagnetic fluctuations at incommensurate wave vectors. The temperature dependence of the amplitudes and energies of both types of excitations indicate the proximity to magnetic instabilities; their competition seems to determine the complex behavior of these materials. In Ca 1.8 Sr 0.2 RuO 4 , which shows a metamagnetic transition, the ferromagnetic fluctuations are strongly suppressed at low temperature, but appear at higher temperature or application of a magnetic field. In the high-field phase of Ca 1.8 Sr 0.2 RuO 4 above the metamagnetic transition, a ferromagnetic magnon dominates the excitation spectrum. Polarized neutron scattering revealed the existence of a very broad signal around the zone centre, in addition to the well-known incommensurate excitations at Q=(0.3,0.3,0) in the unconventional superconductor Sr 2 RuO 4 . With this additional contribution, it is possible to set up a general model for the Q-dependent magnetic susceptibility, which is well consistent with the results of other measurement methods that do not resolve the Q-dependence. Upon doping with Ti, the incommensurate fluctuations are enhanced, in particular near the critical concentration for the onset of magnetic order, but no divergence down to very low temperature is observed. In the bilayer Ti-doped Ca 3 Ru 2 O 7 , the existence of magnetic order with a propagation vector of about ((1)/(4),(1)/(4),0) has been discovered and characterized in detail. Above and below T N , excitations at this wave vector and another one, related to Sr 3 Ru 2 O 7 , have been

  6. Magnetic classification of meteorites

    Science.gov (United States)

    Rochette, P.; Sagnotti, L.; Consolmagno, G.; Denise, M.; Folco, L.; Gattacceca, J.; Osete, M.; Pesonen, L.

    2003-04-01

    Magnetic susceptibility (X) provides a versatile rapid and non destructive way to quantify the amount of magnetic minerals (FeNi metal, magnetic oxides and sulfides) on large volume of material. As petrological studies of meteorites suggest that this parameter should be quite discriminant, we assembled a database of measurements on about 1200 stony meteorites from various European collections: Helsinki, Madrid, Moscou, Paris, Prague, Roma, Siena, Vatican, and other smaller collections. From 1 to >20 pieces and 1 to >100 cc per meteorite allow to define a representative mean value, using a large coil (8 cm) Kappabridge. For ordinary chondrites, it appears that weathering is responsible for a systematic bias toward low X for Antarctic (Frontier Mountain) and non Antarctic (mainly from Sahara) finds. Once only falls are considered a quite narrow range of X is observed for a given class, with no effect of petrological grade except for LL. This does not support suggested decrease of metal amount with metamorphism for L chondrites. High grade LLs (heated above 400°C) develop the weakly magnetic antitaenite-tetrataenite phases during slow cooling, explaining the difference with low grade taenite-bearing LLs. Once a few % of outliers are excluded, well defined means for H and L are observed with no overlap at 2 s.d.; this agrees with the lack of overlap on metal amount. For non ordinary chondrites and achondrites, weakly magnetic classes are HED, Aubrites and SNC (below LL), strongly ones are E (above H) and Ureilites (in the L-H range), while C chondrites are spread in the whole range, again with each class showing restricted variation. Outliers appeared to be in most cases either misclassified meteorites or misindentified samples, based on petrographic and microprobe investigations of thin sections from outlying samples. It appears that systematic magnetic screening of large collections is an efficient way to detect erroneous sample identification, due to exchange with

  7. Magnetism in layered Ruthenates

    Energy Technology Data Exchange (ETDEWEB)

    Steffens, Paul C.

    2008-07-01

    In this thesis, the magnetism of the layered Ruthenates has been studied by means of different neutron scattering techniques. Magnetic correlations in the single-layer Ruthenates of the series Ca{sub 2-x}Sr{sub x}RuO{sub 4} have been investigated as function of Sr-concentration (x=0.2 and 0.62), temperature and magnetic field. These inelastic neutron scattering studies demonstrate the coexistence of ferromagnetic paramagnon scattering with antiferromagnetic fluctuations at incommensurate wave vectors. The temperature dependence of the amplitudes and energies of both types of excitations indicate the proximity to magnetic instabilities; their competition seems to determine the complex behavior of these materials. In Ca{sub 1.8}Sr{sub 0.2}RuO{sub 4}, which shows a metamagnetic transition, the ferromagnetic fluctuations are strongly suppressed at low temperature, but appear at higher temperature or application of a magnetic field. In the high-field phase of Ca{sub 1.8}Sr{sub 0.2}RuO{sub 4} above the metamagnetic transition, a ferromagnetic magnon dominates the excitation spectrum. Polarized neutron scattering revealed the existence of a very broad signal around the zone centre, in addition to the well-known incommensurate excitations at Q=(0.3,0.3,0) in the unconventional superconductor Sr{sub 2}RuO{sub 4}. With this additional contribution, it is possible to set up a general model for the Q-dependent magnetic susceptibility, which is well consistent with the results of other measurement methods that do not resolve the Q-dependence. Upon doping with Ti, the incommensurate fluctuations are enhanced, in particular near the critical concentration for the onset of magnetic order, but no divergence down to very low temperature is observed. In the bilayer Ti-doped Ca{sub 3}Ru{sub 2}O{sub 7}, the existence of magnetic order with a propagation vector of about ((1)/(4),(1)/(4),0) has been discovered and characterized in detail. Above and below T{sub N}, excitations at this

  8. 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.

  9. Nanosecond-resolved temperature measurements using magnetic nanoparticles

    Science.gov (United States)

    Xu, Wenbiao; Liu, Wenzhong; Zhang, Pu

    2016-05-01

    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.

  10. 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.

  11. Accuracy of the morphology enabled dipole inversion (MEDI) algorithm for quantitative susceptibility mapping in MRI.

    Science.gov (United States)

    Liu, Tian; Xu, Weiyu; Spincemaille, Pascal; Avestimehr, A Salman; Wang, Yi

    2012-03-01

    Determining the susceptibility distribution from the magnetic field measured in a magnetic resonance (MR) scanner is an ill-posed inverse problem, because of the presence of zeroes in the convolution kernel in the forward problem. An algorithm called morphology enabled dipole inversion (MEDI), which incorporates spatial prior information, has been proposed to generate a quantitative susceptibility map (QSM). The accuracy of QSM can be validated experimentally. However, there is not yet a rigorous mathematical demonstration of accuracy for a general regularized approach or for MEDI specifically. The error in the susceptibility map reconstructed by MEDI is expressed in terms of the acquisition noise and the error in the spatial prior information. A detailed analysis demonstrates that the error in the susceptibility map reconstructed by MEDI is bounded by a linear function of these two error sources. Numerical analysis confirms that the error of the susceptibility map reconstructed by MEDI is on the same order of the noise in the original MRI data, and comprehensive edge detection will lead to reduced model error in MEDI. Additional phantom validation and human brain imaging demonstrated the practicality of the MEDI method.

  12. High field magnetization of (Rx Y1-x)Fe2 compounds

    International Nuclear Information System (INIS)

    Guimaraes, A.P.; Alves, K.M.B.

    1991-01-01

    The magnetization of the pseudo-binary intermetallic compounds (D Y x Y 1-x )Fe 2 and (Er x Y 1-x )Fe 2 was studied in high magnetic fields (up to 20 T). The saturation magnetization shows a minimum as a function of concentration, due to the anti parallel coupling of the R and Fe moments. From the magnetization curve in the high field region we derived the spontaneous magnetization and high field susceptibility, as a function of concentration. The susceptibilities, coercive fields and the anisotropy terms show maxima in the 20 - 40% concentration range. (author)

  13. 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

  14. The organic matter content of street dust in Liverpool, UK, and its association with dust magnetic properties

    Science.gov (United States)

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

    The organic matter content of street dust in Liverpool, UK, measured by means of the loss-on-ignition method, is 4.0% on average (standard deviation 1.3%). The magnetic measurements of the street dust samples indicate that the dominant magnetic component is multidomain grains of ferrimagnetic minerals and that superparamagnetic and stable single-domain ferrimagnetic grains and paramagnetic, diamagnetic, and canted antiferromagnetic minerals are present in small magnetic concentrations. Our study demonstrates good linear correlations between the organic matter content and some magnetic mineral concentration-related parameters: low-frequency susceptibility, frequency-dependent susceptibility, susceptibility of anhysteretic remanent magnetisation, and high-field susceptibility. Among them, frequency-dependent susceptibility shows the strongest correlation, suggesting that soil may be an important source of dust organic material. Finally, it is suggested that simple, rapid, and non-destructive magnetic measurements may be used as proxies for the organic matter content in street dust.

  15. Magnetic Hysteresis

    CERN Document Server

    Della Torre, Edward

    2000-01-01

    Understanding magnetic hysteresis is vitally important to the development of the science of magnetism as a whole and to the advancement of practical magnetic device applications. Magnetic Hysteresis, by acclaimed expert Edward Della Torre, presents a clear explanation of the connection between physical principles and phenomenological hysteresis. This comprehensive book offers a lucid analysis that enables the reader to save valuable time by reducing trial-and-error design. Dr. Della Torre uses physical principles to modify Preisach modeling and to describe the complex behavior of magnetic media. While Pretsach modeling is a useful mathematical tool, its congruency and deletion properties present limitations to accurate descriptions of magnetic materials. Step-by-step, this book describes the modifications that can overcome these limitations. Special attention is given to the use of feedback around a Preisach transducer to remove the congruency restriction, and to the use of accommodation and aftereffect model...

  16. Magnetic switching

    International Nuclear Information System (INIS)

    Kirbie, H.C.

    1989-01-01

    Magnetic switching is a pulse compression technique that uses a saturable inductor (reactor) to pass pulses of energy between two capacitors. A high degree of pulse compression can be achieved in a network when several of these simple, magnetically switched circuits are connected in series. Individual inductors are designed to saturate in cascade as a pulse moves along the network. The technique is particularly useful when a single-pulse network must be very reliable or when a multi-pulse network must operate at a high pulse repetition frequency (PRF). Today, magnetic switches trigger spark gaps, sharpen the risetimes of high energy pulses, power large lasers, and drive high PRF linear induction accelerators. This paper will describe the technique of magnetic pulse compression using simple networks and design equations. A brief review of modern magnetic materials and of their role in magnetic switch design will be presented. 12 refs., 8 figs

  17. Planetary Magnetism

    Science.gov (United States)

    Connerney, J. E. P.

    2007-01-01

    The chapter on Planetary Magnetism by Connerney describes the magnetic fields of the planets, from Mercury to Neptune, including the large satellites (Moon, Ganymede) that have or once had active dynamos. The chapter describes the spacecraft missions and observations that, along with select remote observations, form the basis of our knowledge of planetary magnetic fields. Connerney describes the methods of analysis used to characterize planetary magnetic fields, and the models used to represent the main field (due to dynamo action in the planet's interior) and/or remnant magnetic fields locked in the planet's crust, where appropriate. These observations provide valuable insights into dynamo generation of magnetic fields, the structure and composition of planetary interiors, and the evolution of planets.

  18. Pulse sequences for contrast-enhanced magnetic resonance imaging

    International Nuclear Information System (INIS)

    Graves, Martin J.

    2007-01-01

    The theory and application of magnetic resonance imaging (MRI) pulse sequences following the administration of an exogenous contrast agent are discussed. Pulse sequences are categorised according to the contrast agent mechanism: changes in proton density, relaxivity, magnetic susceptibility and resonant frequency shift. Applications in morphological imaging, magnetic resonance angiography, dynamic imaging and cell labelling are described. The importance of optimising the pulse sequence for each application is emphasised

  19. Effect of hydrocarbon-contaminated fluctuating groundwater on magnetic properties of shallow sediments

    Czech Academy of Sciences Publication Activity Database

    Ameen, N. N.; Klueglein, N.; Appel, E.; Petrovský, Eduard; Kappler, A.; Leven, C.

    2014-01-01

    Roč. 58, č. 3 (2014), s. 442-460 ISSN 0039-3169 R&D Projects: GA MŠk(CZ) LG13042 Institutional support: RVO:67985530 Keywords : environmental magnetism * magnetic susceptibility * groundwater table fluctuation * hydrocarbon contamination * magnetite formation Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.806, year: 2014

  20. Magnetic record of extreme marine inundation events at Las Salinas site, Jalisco, Mexican Pacific coast

    Czech Academy of Sciences Publication Activity Database

    Černý, Jan; Ramírez-Herrera, M.-T.; Bógalo, M.-F.; Goguitchaichvili, A.; Castillo-Aja, R.; Morales, J.; Sanchez-Cabeza, J. A.; Ruiz-Fernandez, A. C.

    2016-01-01

    Roč. 58, č. 3 (2016), s. 342-357 ISSN 0020-6814 Institutional support: RVO:67985831 Keywords : anisotropy of magnetic susceptibility (AMS) * rock magnetic properties * tsunami * thermomagnetic curves * Mexican Pacific coast * variability Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 2.262, year: 2016