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Sample records for high-pressure magnetic susceptibility

  1. Magnetic and Superconducting Materials at High Pressures

    Energy Technology Data Exchange (ETDEWEB)

    Struzhkin, Viktor V. [Carnegie Inst. of Washington, Washington, DC (United States)

    2015-03-24

    The work concentrates on few important tasks in enabling techniques for search of superconducting compressed hydrogen compounds and pure hydrogen, investigation of mechanisms of high-Tc superconductivity, and exploring new superconducting materials. Along that route we performed several challenging tasks, including discovery of new forms of polyhydrides of alkali metal Na at very high pressures. These experiments help us to establish the experimental environment that will provide important information on the high-pressure properties of hydrogen-rich compounds. Our recent progress in RIXS measurements opens a whole field of strongly correlated 3d materials. We have developed a systematic approach to measure major electronic parameters, like Hubbard energy U, and charge transfer energy Δ, as function of pressure. This technique will enable also RIXS studies of magnetic excitations in iridates and other 5d materials at the L edge, which attract a lot of interest recently. We have developed new magnetic sensing technique based on optically detected magnetic resonance from NV centers in diamond. The technique can be applied to study superconductivity in high-TC materials, to search for magnetic transitions in strongly correlated and itinerant magnetic materials under pressure. Summary of Project Activities; development of high-pressure experimentation platform for exploration of new potential superconductors, metal polyhydrides (including newly discovered alkali metal polyhydrides), and already known superconductors at the limit of static high-pressure techniques; investigation of special classes of superconducting compounds (high-Tc superconductors, new superconducting materials), that may provide new fundamental knowledge and may prove important for application as high-temperature/high-critical parameter superconductors; investigation of the pressure dependence of superconductivity and magnetic/phase transformations in 3d transition metal compounds, including

  2. Superconductivity from magnetic elements under high pressure

    International Nuclear Information System (INIS)

    Shimizu, Katsuya; Amaya, Kiichi; Suzuki, Naoshi; Onuki, Yoshichika

    2006-01-01

    Can we expect the appearance of superconductivity from magnetic elements? In general, superconductivity occurs in nonmagnetic metal at low temperature and magnetic impurities destroy superconductivity; magnetism and superconductivity are as incompatible as oil and water. Here, we present our experimental example of superconducting elements, iron and oxygen. They are magnetic at ambient pressure, however, they become nonmagnetic under high pressure, then superconductor at low temperature. What is the driving force of the superconductivity? Our understanding in the early stages was a simple scenario that the superconductive state was obtained as a consequence of an emergence of the nonmagnetic states. In both cases, we may consider another scenario for the appearance of superconductivity; the magnetic fluctuation mechanism in the same way as unconventional superconductors

  3. Nuclear magnetic resonance studies at high pressures

    International Nuclear Information System (INIS)

    Jonas, J.

    1980-01-01

    Recent advances in the field of NMR spectroscopy at high pressure are reviewed. After a brief discussion of two novel experimental techniques, the main focus of this review is on several specific studies which illustrate the versatility and power of this high pressure field. Experimental aspects of NMR measurements at high pressure and high temperature and the techniques for the high resolution NMR spectroscopy at high pressure are discussed. An overview of NMR studies of the dynamic structure of simple polyatomic liquids and hydrogen bonded liquids is followed by a discussion of high resolution spectroscopy at high pressure. Examples of NMR studies of disordered organic solids and polymers conclude the review. (author)

  4. Review of modern instrumentation for magnetic measurements at high pressure and low temperature

    International Nuclear Information System (INIS)

    Wang, X.; Kamenev, K.V.

    2015-01-01

    High-pressure magnetic susceptibility experiments can provide insights into the changes in magnetic behavior and electric properties which can accompany extreme compressions of material. Instrumentation plays an important role in the experimental work in this field since 1990s. Here we present a comprehensive review of the high-pressure instrumentation development for magnetic measurement from the engineering perspective in the last 20 years. Suitable nonmagnetic materials for high pressure cell are introduced initially. Then we focus on the existing cells developed for magnetic property measurement system (MPMS) SQUID magnetometer from Quantum Design (USA). Two categories of high pressure cells for this system are discussed in detail respectively. Some high pressure cells with built-in magnetic measurement system are also reviewed

  5. Effects of high pressure on the magnetism of ErCo.sub.2./sub..

    Czech Academy of Sciences Publication Activity Database

    Míšek, M.; Prokleška, J.; Sechovský, V.; Turčinková, D.; Prchal, J.; Kusmartseva, A.F.; Kamenev, K. V.; Kamarád, Jiří

    2012-01-01

    Roč. 111, č. 7 (2012), "07E132-1"-"07E132-3" ISSN 0021-8979 Institutional research plan: CEZ:AV0Z10100521 Keywords : cobalt alloys * erbium alloys * ferrimagnetic materials * ferromagnetic mataterials * high- pressure effects * magnetic moments * magnetic susceptibility Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.210, year: 2012

  6. Evidence of new high-pressure magnetic phases in Fe-Pt Invar alloy

    International Nuclear Information System (INIS)

    Matsushita, M.; Endo, S.; Miura, K.; Ono, F.

    2003-01-01

    To investigate the magnetic properties of disordered Fe 70 Pt 30 Invar alloy under high pressure, measurements of the real part of the AC susceptibility (χ) were made under pressure up to 7.5 GPa in the temperature range 4.2-385 K using a cubic anvil high-pressure apparatus. The Curie temperature (T C ) decreased with increasing pressure, and then, two new high-pressure magnetic phases appeared. These results show that the ferromagnetism of Fe-Pt Invar alloy becomes weaker, and the antiferromagnetic interaction becomes dominant with increasing pressure

  7. Magnetic structures of erbium under high pressure

    DEFF Research Database (Denmark)

    Kawano, S.; Lebech, B.; Achiwa, N.

    1993-01-01

    Neutron diffraction studies of the magnetic structures of erbium metal at 4.5 K and 11.5 kbar hydrostatic pressure have revealed that the transition to a conical structure at low temperatures is suppressed and that the cycloidal structure, with modulation vector Q congruent-to (2/7 2pi/c)c persists...

  8. Magnetization at high pressure in CeP

    Science.gov (United States)

    Naka, T.; Matsumoto, T.; Okayama, Y.; Môri, N.; Haga, Y.; Suzuki, T.

    1995-02-01

    We have investigated the pressure dependence of magnetization below 60 K up to 1.6 GPa in the low-carrier concentration system CeP showing two step transitions at T = TL and TH under high pressure. At high pressure, M( P, T) exhibits a maximum at around the lower transition temperature TL. This behavior implies that the magnetic state changes at TL. The pressure dependence of isothermal magnetization M( P) is different above and below TL. In fact, M( P) below TL exhibits a maximum at around 1.4 GPa, whereas M( P) above TL increases steeply with pressure up to 1.6 GPa.

  9. Magnetism in UPtAl under high pressure

    Czech Academy of Sciences Publication Activity Database

    Honda, F.; Eto, T.; Oomi, G.; Sechovský, V.; Andreev, Alexander V.; Takeshita, N.; Môri, N.

    2002-01-01

    Roč. 52, č. 2 (2002), s. 263-266 ISSN 0011-4626. [Czech and Slovak Conference on Magnetism /11./. Košice, 20.08.2001-23.08.2001] Institutional research plan: CEZ:AV0Z1010914 Keywords : UPtAl * high pressure * electrical resistivity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.311, year: 2002

  10. Effects of high pressures on magnetism in UNiGa

    Czech Academy of Sciences Publication Activity Database

    Míšek, M.; Sechovský, V.; Kamarád, Jiří; Prokleška, J.

    2010-01-01

    Roč. 30, č. 1 (2010), 8-11 ISSN 0895-7959 Grant - others:GAUK(CZ) 129009 Institutional research plan: CEZ:AV0Z10100521 Keywords : high pressure * uniaxial stress * magnetism Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.995, year: 2010

  11. High pressure apparatus transport properties study in high magnetic field

    Czech Academy of Sciences Publication Activity Database

    Honda, F.; Sechovský, V.; Mikulina, O.; Kamarád, Jiří; Alsmadi, A. M.; Nakotte, H.; Lacerda, A. H.

    2002-01-01

    Roč. 16, 20, 21 & 22 (2002), s. 3330-3333 ISSN 0217-9792 R&D Projects: GA ČR GP202/01/D045; GA ČR GA202/00/1217; GA MŠk ME 165 Grant - others:NSF(XX) DMR-0094241 Institutional research plan: CEZ:AV0Z1010914 Keywords : high-pressure apparatus Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.604, year: 2002

  12. Magnetic phase diagram of Ce2Fe17 under high pressures in high magnetic fields

    International Nuclear Information System (INIS)

    Ishikawa, Fumihiro; Goto, Tsuneaki; Fujii, Hironobu

    2003-01-01

    The magnetization of Ce 2 Fe 17 was precisely measured under high pressures up to 1.2 GPa in magnetic fields up to 18 T. The magnetic phase diagram in the B-T plane is determined at 0, 0.3, 0.4, 0.6, 0.9 and 1.2 GPa. At 0 GPa, five magnetic phases exist and the application of high pressure produces two additional magnetic phases. The shape of the phase diagram changes drastically with increasing pressure

  13. Magnetic phase diagram of UNi2Si2 under magnetic field and high-pressure

    International Nuclear Information System (INIS)

    Honda, F.; Oomi, G.; Svoboda, P.; Syshchenko, A.; Sechovsky, V.; Khmelevski, S.; Divis, M.; Andreev, A.V.; Takeshita, N.; Mori, N.; Menovsky, A.A.

    2001-01-01

    Measurements of electrical resistance under high pressure and neutron diffraction in high-magnetic field of single crystalline UNi 2 Si 2 have been performed. We have found the analogy between the p-T and B-T magnetic phase diagrams. It is also found that the propagation vector q Z of incommensurate antiferromagnetic phase decreases with increasing magnetic field. A new pronounced pressure-induced incommensurate-commensurate magnetic phase transition has been detected

  14. Structural stability at high pressure, electronic, and magnetic properties of BaFZnAs: A new candidate of host material of diluted magnetic semiconductors

    International Nuclear Information System (INIS)

    Chen Bi-Juan; Deng Zheng; Wang Xian-Cheng; Feng Shao-Min; Yuan Zhen; Zhang Si-Jia; Liu Qing-Qing; Jin Chang-Qing

    2016-01-01

    The layered semiconductor BaFZnAs with the tetragonal ZrCuSiAs-type structure has been successfully synthesized. Both the in-situ high-pressure synchrotron x-ray diffraction and the high-pressure Raman scattering measurements demonstrate that the structure of BaFZnAs is stable under pressure up to 17.5 GPa at room temperature. The resistivity and the magnetic susceptibility data show that BaFZnAs is a non-magnetic semiconductor. BaFZnAs is recommended as a candidate of the host material of diluted magnetic semiconductor. (special topic)

  15. Future pulsed magnetic field applications in dynamic high pressure research

    International Nuclear Information System (INIS)

    Fowler, C.M.; Caird, R.S.; Hawke, R.S.; Burgess, T.J.

    1977-01-01

    The generation of large pressures by magnetic fields to obtain equation of state information is of fairly recent origin. Magnetic fields used in compression experiments produce an almost isentropic sample compression. Axial magnetic field compression is discussed together with a few results chosen to show both advantages and limitations of the method. Magnetic compression with azimuthal fields is then considered. Although there are several potential pitfalls, the possibilities are encouraging for obtaining very large pressures. Next, improved diagnostic techniques are considered. An x-ray ''streaking camera'' is proposed for volume measurements and a more detailed discussion is given on the use of the shift of the ruby fluorescence lines for pressure measurements. Finally, some additional flux compression magnetic field sources are discussed briefly. 5 figures, 2 tables

  16. High pressure cells for magnetic measurements - destruction and functional tests

    Czech Academy of Sciences Publication Activity Database

    Kamarád, Jiří; Machátová, Zuzana; Arnold, Zdeněk

    2004-01-01

    Roč. 75, č. 11 (2004), s. 5022-5025 ISSN 0034-6748 R&D Projects: GA ČR GA202/02/0739; GA AV ČR IAA1010315 Institutional research plan: CEZ:AV0Z1010914 Keywords : pressure cells * pressure transmitting media * CuBe * MP35N Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.226, year: 2004

  17. Magnetic anisotropy of pure and doped YbInCu sub 4 compounds at ambient and high pressures

    CERN Document Server

    Mushnikov, N V; Rozenfeld, E V; Yoshimura, K; Zhang, W; Yamada, M; Kageyama, H

    2003-01-01

    The susceptibility and high-field magnetization of single-crystalline Yb sub 1 sub - sub x Y sub x InCu sub 4 (x = 0, 0.2 and 0.3) samples have been measured for different field orientations at ambient and high pressures. The compounds with x = 0 and 0.2 undergo a first-order valence transition from the intermediate-valence state to the trivalent state on increasing either temperature or magnetic field. The magnetization and susceptibility of these compounds have appreciable anisotropy in both states. The magnetic phase diagram of Yb sub 1 sub - sub x Y sub x InCu sub 4 determined at ambient pressure is also anisotropic, which is explained by the crystal-field calculations for the free Yb ion in the high-temperature phase. Moreover, the low-temperature magnetization process for x = 0.2 and 0.3 has been measured in low fields under high pressure; it shows anisotropic ferromagnetic ordering.

  18. 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

  19. Ferroelectric and magnetic properties in high-pressure synthesized BiFeO3 compound

    International Nuclear Information System (INIS)

    Zhai, L.; Shi, Y.G.; Gao, J.L.; Tang, S.L.; Du, Y.W.

    2011-01-01

    Highlights: → A high-density polycrystalline BiFeO 3 compound was synthesized by high-pressure annealing method. → The sample showed weak ferromagnetic at room temperature, which could be attributed to the lattice distortion induced by the high-pressure annealing. → Irregular domains were observed on the surface of the sample by piezoresponse force microscopy, and a typical hysteresis loop was obtained. - Abstract: High-density polycrystalline BiFeO 3 compound was synthesized by high-pressure annealing. Measurements of crystal structure, magnetic, and ferroelectric properties were made on the sample. It was found that the sample was almost single phase with a distorted R3c structure. The results of the X-ray photoelectron spectra demonstrate that the oxidation state of Fe in the sample is Fe 3+ . The room-temperature field dependence of magnetization for BiFeO 3 exhibits a hysteretic behavior. The observed weak ferromagnetism could be ascribed to the lattice distortion induced by the high-pressure annealing. In addition, the local ferroelectric performance of the sample was studied by piezoresponse force microscopy.

  20. Transport and magnetic properties in the Heusler-type Fe2+xV1-xAl under high pressure

    International Nuclear Information System (INIS)

    Naka, T.; Adschiri, T.; Fukuda, K.; Ishikawa, F.; Yamada, Yuh; Takaesu, Y.; Nakama, T.; Yagasaki, K.; Matsushita, A.

    2007-01-01

    We report magnetic susceptibility and electrical resistivity under high pressure on polycrystalline Fe 2+x V 1-x Al, which exhibits the ferromagnetic transition at x>0. The pseudogap band structure, magnetic defects and lower number of conduction carrier seem to result in the spin fluctuation, the enhancement of thermoelectric power and other unique properties in this system. On the other hand, the excess V-atom brings about the variable range hopping conduction at lower temperature that is affected by external pressure. The pressure effects on the transition temperature, T c , and magnetization at low temperature reveal that the magnetism can be described by the self-consistent renormalization (SCR) theory

  1. Magnetic properties of the filled skutterudite-type structure compounds GdRu4P12 and TbRu4P12 synthesized under high pressure

    OpenAIRE

    Sekine, C; Uchiumi, T; Shirotani, I; Matsuhira, kazuyuki; Sakakibara, T; Goto, T; Yagi, T

    2000-01-01

    We have succeeded in synthesizing filled skutterudite-type structure compounds GdRu4P12 and TbRu4P12 under high pressure. The magnetic properties of GdRu4P12 and TbRu4P12 have been studied by means of electrical resistivity, magnetic susceptibility, and magnetization measurements. Magnetic experiments suggest that the Gd and Tb ions in the compounds have trivalent state. The compound GdRu4P12 displays features that suggest the occurrence of antiferromagnetic ordering below TN=22 K. In TbRu4P1...

  2. High pressure metallization of Mott Insulators: Magnetic, structural and electronic properties

    International Nuclear Information System (INIS)

    Pasternak, M.P.; Hearne, G.; Sterer, E.; Taylor, R.D.; Jeanloz, R.

    1993-01-01

    High pressure studies of the insulator-metal transition in the (TM)I 2 (TM = V, Fe, Co and Ni) compounds are described. Those divalent transition-metal iodides are structurally isomorphous and classified as Mott Insulators. Resistivity, X-ray diffraction and Moessbauer Spectroscopy were employed to investigate the electronic, structural, and magnetic properties as a function of pressure both on the highly correlated and on the metallic regimes

  3. Theory and Practice - Measuring High-Pressure Electronic and Magnetic Properties

    International Nuclear Information System (INIS)

    Hemley, R.J.; Struzhkin, V.V.; Cohen, R.E.

    2008-01-01

    Measurements of the electronic and magnetic properties of Earth and planetary materials at high pressure play a crucial role in modern geoscience. There have been numerous advances in the field, primarily as a result of developments in diamond-anvil cell methods. In particular, synchrotron radiation techniques play an especially important role. The chapter begins with a short review of fundamental properties of the relevant materials, with emphasis on how these are altered under very high pressures and temperatures of the Earth's deep interior, followed by a discussion of different classes of electronic and magnetic excitations. Various techniques currently used for high-pressure studies are then described, beginning with optical spectroscopies, Moessbauer spectroscopy, elastic X-ray and neutron scattering, many new X-ray spectroscopy and inelastic scattering methods, transport techniques, and finally resonance methods. Selected examples of the techniques are given, with a common theme being the high P-T behavior of iron-containing oxides, silicates, and metals at conditions found throughout the Earth's interior. Applications to upper-mantle phases, 'simple' oxides, silicate perovskite and post-perovskite, volatiles, and iron and iron alloys are discussed, with an emphasis given to integrated studies utilizing a combination of different techniques to understand high P-T electronic and magnetic phenomena.

  4. Magnetic and Structural Phase Transitions in Thulium under High Pressures and Low Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Vohra, Yogesh K.; Tsoi, Georgiy M.; Samudrala, Gopi K. [UAB

    2017-10-01

    The nature of 4f electrons in many rare earth metals and compounds may be broadly characterized as being either "localized" or "itinerant", and is held responsible for a wide range of physical and chemical properties. The pressure variable has a very dramatic effect on the electronic structure of rare earth metals which in turn drives a sequence of structural and magnetic transitions. We have carried out four-probe electrical resistance measurements on rare earth metal Thulium (Tm) under high pressures to 33 GPa and low temperatures to 10 K to monitor the magnetic ordering transition. These studies are complemented by angle dispersive x-ray diffraction studies to monitor crystallographic phase transitions at high pressures and low temperatures. We observe an abrupt increase in magnetic ordering temperature in Tm at a pressure of 17 GPa on phase transition from ambient pressure hcp-phase to α-Sm phase transition. In addition, measured equation of state (EOS) at low temperatures show anomalously low thermal expansion coefficients likely linked to magnetic transitions.

  5. A reactor for high-throughput high-pressure nuclear magnetic resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Beach, N. J.; Knapp, S. M. M.; Landis, C. R., E-mail: landis@chem.wisc.edu [Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53719 (United States)

    2015-10-15

    The design of a reactor for operando nuclear magnetic resonance (NMR) monitoring of high-pressure gas-liquid reactions is described. The Wisconsin High Pressure NMR Reactor (WiHP-NMRR) design comprises four modules: a sapphire NMR tube with titanium tube holder rated for pressures as high as 1000 psig (68 atm) and temperatures ranging from −90 to 90 °C, a gas circulation system that maintains equilibrium concentrations of dissolved gases during gas-consuming or gas-releasing reactions, a liquid injection apparatus that is capable of adding measured amounts of solutions to the reactor under high pressure conditions, and a rapid wash system that enables the reactor to be cleaned without removal from the NMR instrument. The WiHP-NMRR is compatible with commercial 10 mm NMR probes. Reactions performed in the WiHP-NMRR yield high quality, information-rich, and multinuclear NMR data over the entire reaction time course with rapid experimental turnaround.

  6. Magnetization and Hall effect under high pressure in NaV 6O 11

    Science.gov (United States)

    Naka, T.; Matsumoto, T.; Kanke, Y.; Murata, K.

    1995-02-01

    We have investigated the pressure dependences of magnetization and the Hall coefficient in the ferromagnetic vanadium oxide NaV 6O 11 up to 1.2 GPa. Structural transitions (hexagonal-hexagonal-orthorhombic) occur at TH = 245 K and TL = 35 K at ambient pressure. Meanwhile, the susceptibility obeys the Curie-Weiss law X = C/( T - θ) with antiferromagnetic correlation of θ TH, with ferromagnetic correlation of θ TH. The spontaneous magnetization appears below Tc = 64.2 K. With increasing pressure, Tc and magnetization M( T TH increases. The sign of the Hall coefficient changes continuously (negative-positive-negative) at around T ≈ 170 K and 75 K.

  7. Characterization of magnetically impelled arc butt welded T11 tubes for high pressure applications

    Directory of Open Access Journals (Sweden)

    R. Sivasankari

    2015-09-01

    Full Text Available Magnetically impelled arc butt (MIAB welding is a pressure welding process used for joining of pipes and tubes with an external magnetic field affecting arc rotation along the tube circumference. In this work, MIAB welding of low alloy steel (T11 tubes were carried out to study the microstructural changes occurring in thermo-mechanically affected zone (TMAZ. To qualify the process for the welding applications where pressure could be up to 300 bar, the MIAB welds are studied with variations of arc current and arc rotation time. It is found that TMAZ shows higher hardness than that in base metal and displays higher weld tensile strength and ductility due to bainitic transformation. The effect of arc current on the weld interface is also detailed and is found to be defect free at higher values of arc currents. The results reveal that MIAB welded samples exhibits good structural property correlation for high pressure applications with an added benefit of enhanced productivity at lower cost. The study will enable the use of MIAB welding for high pressure applications in power and defence sectors.

  8. The role of equilibrium volume and magnetism on the stability of iron phases at high pressures.

    Science.gov (United States)

    Alnemrat, S; Hooper, J P; Vasiliev, I; Kiefer, B

    2014-01-29

    The present study provides new insights into the pressure dependence of magnetism by tracking the hybridization between crystal orbitals for pressures up to 600 GPa in the known hcp, bcc and fcc iron. The Birch-Murnaghan equation of state parameters are; bcc: V0 = 11.759 A(3)/atom, K0 = 177.72 GPa; hcp: V0 = 10.525 A(3)/atom, K0 = 295.16 GPa; and fcc: V0 = 10.682 A(3)/atom, K0 = 274.57 GPa. These parameters compare favorably with previous studies. Consistent with previous studies we find that the close-packed hcp and fcc phases are non-magnetic at pressures above 50 GPa and 60 GPa, respectively. The principal features of magnetism in iron are predicted to be invariant, at least up to ∼6% overextension of the equilibrium volume. Our results predict that magnetism for overextended fcc iron disappears via an intermediate spin state. This feature suggests that overextended lattices can be used to stabilize particular magnetic states. The analysis of the orbital hybridization shows that the magnetic bcc structure at high pressures is stabilized by splitting the majority and minority spin bands. The bcc phase is found to be magnetic at least up to 600 GPa; however, magnetism is insufficient to stabilize the bcc phase itself, at least at low temperatures. Finally, the analysis of the orbital contributions to the total energy provides evidence that non-magnetic hcp and fcc phases are likely more stable than bcc at core earth pressures.

  9. Moessbauer high pressure and magnetic field studies of the superconductor FeSe

    Energy Technology Data Exchange (ETDEWEB)

    Ksenofontov, Vadim; Felser, Claudia [Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg - University, Mainz (Germany); Wortmann, Gerhard [Department of Physics, University of Paderborn, Paderborn (Germany); Trojan, Ivan; Palasyuk, Taras; Medvedev, Sergey; Eremets, Michail [Max-Planck-Institute for Chemistry, Mainz (Germany); McQueen, Tyrel M.; Cava, Richard J. [Department of Chemistry, Princeton University, Princeton (United States)

    2010-07-01

    Superconducting FeSe has been investigated by Moessbauer spectroscopy applying high pressure and strong external magnetic fields. It was found that pressure-induced structural phase transition between tetragonal and hexagonal modifications is accompanied by increased distortion of local surrounding of Fe atoms. Appearance of the hexagonal phase above 7.2 GPa is accompanied by degradation of superconducting properties of FeSe. Low-temperature measurements demonstrated that the ground states in both orthorhombic and hexagonal phases of FeSe are nonmagnetic. Moessbauer measurements in the external magnetic field below transition to the superconducting state revealed zero electron spin density on Fe atoms. Interpretation of Moessbauer spectra of FeSe in the Shubnikov phase is discussed.

  10. 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

  11. Tuning the magnetic properties of pure hafnium by high pressure torsion

    International Nuclear Information System (INIS)

    Cepeda-Jiménez, C.M.; Beltrán, J.I.; Hernando, A.; García, M.A.; Ynduráin, F.; Zhilyaev, A.; Pérez-Prado, M.T.

    2017-01-01

    This work demonstrates that room temperature (RT) ferromagnetism might be triggered in pure hafnium (Hf), a classic paramagnet, by severe plastic deformation (SPD) via high pressure torsion (HPT). The origin of this phenomenon is elucidated by a combined approach including density functional theory (DFT) calculations and transmission electron microscopy (TEM). In particular, it is shown that the elastic lattice distorsions induced in pure Hf as a consequence of grain refinement down to the nanocrystalline regime by HPT lead to the development of a new monoclinic crystalline structure that exhibits a spontaneous magnetization at RT. DFT calculations are utilized to prove that local stretching of the original pure Hf hexagonal close packed (hcp) lattice along specific pyramidal directions, due to the presence of internal stresses in the deformed nanostructure, may give rise to the emergence of the monoclinic phase, which is endowed with a net magnetic moment. An excellent agreement is found between DFT calculations and experimental TEM observations, which provide a first evidence of the presence of the pure Hf monoclinic crystal lattice. This work shows that SPD may constitute a viable, yet widely unexplored, strategy to tune the magnetic properties and, in particular, to induce RT ferromagnetism in bulk non-magnetic metals.

  12. Development of dispersion interferometer for magnetic confinement plasmas and high-pressure plasmas

    Science.gov (United States)

    Akiyama, T.; Yasuhara, R.; Kawahata, K.; Nakayama, K.; Okajima, S.; Urabe, K.; Terashima, K.; Shirai, N.

    2015-09-01

    A CO2 laser dispersion interferometer (DI) has been developed for both magnetically fusion plasmas and high pressure industrial plasmas. The DI measures the phase shift caused by dispersion in a medium. Therefore, it is insensitive to the mechanical vibrations and changes in the neutral gas density, which degrade the resolution of the electron density measurement. We installed the DI on the Large Helical Device (LHD) and demonstrated a high density resolution of 2× 1017 m-3 without any vibration-free bench. The measured electron density with the DI shows good agreement with results of the existing far infrared laser (a wavelength of 119 μ m) interferometer. The DI system is also applied to the electron density measurement of high-pressure small-scale plasmas. The significant suppression of the phase shift caused by the neutral gas is proven. The achieved density resolution was 1.5× 1019 m-3 with a response time of 100 μ s. A shorter version of this contribution is due to be published in PoS at: 1st EPS conference on Plasma Diagnostics

  13. High-pressure nuclear magnetic resonance studies of fuel cell membranes

    Science.gov (United States)

    Mananga, Eugene Stephane

    This thesis focuses on the use of high pressure NMR to study transport properties in electrolyte membranes used for fuel cells. The main concern is in studying the self-diffusion coefficients of ions and molecules in membranes and solutions, which can be used to characterize electrolytes in fuel cells. For this purpose, a high-pressure fringe field NMR method to study transport properties in material systems useful for fuel cell and battery electrolytes, was designed, developed, and implemented. In this investigation, pressure is the thermodynamic variable to obtain additional information about the ionic transport process, which could yield the crucial parameter, activation volume. Most of the work involves proton NMR, with additional investigations of others nuclei, such as fluorine, phosphorus and lithium. Using the FFG method, two fuel cell membrane types (NAFION-117, SPTES), and different dilutions of phosphoric acid were investigated, as was LiTf salt in Diglyme solution, which is used as a lithium battery electrolyte. In addition to high-pressure NMR diffusion measurements carried out in the fringe field gradient for the investigation of SPTES, pulse field gradient spin echo NMR was also used to characterize the water diffusion, in addition to measuring diffusion rates as a function of temperature. This second method allows us to measure distinct diffusion coefficients in cases where the different nuclear (proton) environments can be resolved in the NMR spectrum. Polymer electrolyte systems, in which the mobility of both cations and anions is probed by NMR self-diffusion measurements using standard pulsed field gradient methods and static gradient measurements as a function of applied hydrostatic pressure, were also investigated. The material investigated is the low molecular weight liquid diglyme/LiCF3SO3 (LiTf) complexes which can be used as electrolytes in lithium batteries. Finally, high-pressure diffusion coefficient measurements of phosphoric acid in

  14. Lattice dynamics, elasticity and magnetic abnormality in ordered crystalline alloys Fe3Pt at high pressures

    Science.gov (United States)

    Cheng, Tai-min; Yu, Guo-Liang; Su, Yong; Ge, Chong-Yuan; Zhang, Xin-Xin; Zhu, Lin; Li, Lin

    2018-05-01

    The ordered crystalline Invar alloy Fe3Pt is in a special magnetic critical state, under which the lattice dynamic stability of the system is extremely sensitive to external pressures. We studied the pressure dependence of enthalpy and magnetism of Fe3Pt in different crystalline alloys by using the first-principles projector augmented-wave method based on the density functional theory. Results show that the P4/mbm structure is the ground state structure and is more stable relative to other structures at pressures below 18.54 GPa. The total magnetic moments of L12, I4/mmm and DO22 structures decrease rapidly with pressure and oscillate near the ferromagnetic collapse critical pressure. At the pressure of 43 GPa, the ferrimagnetic property in DO22 structure becomes apparently strengthened and its volume increases rapidly. The lattice dynamics calculation for L12 structures at high pressures shows that the spontaneous magnetization of the system in ferromagnetic states induces the softening of the transverse acoustic phonon TA1 (M), and there exists a strong spontaneous volume magnetostriction at pressures below 26.95 GPa. Especially, the lattice dynamics stability is sensitive to pressure, in the pressure range between the ferromagnetic collapse critical pressure (41.9 GPa) and the magnetism completely disappearing pressure (57.25 GPa), and near the pressure of phase transition from L12 to P4/mbm structure (27.27 GPa). Moreover, the instability of magnetic structure leads to a prominent elastic modulus oscillation, and the spin polarizability of electrons near the Fermi level is very sensitive to pressures in that the pressure range. The pressure induces the stability of the phonon spectra of the system at pressures above 57.25 GPa.

  15. Magnetic susceptibility of semiconductor melts

    International Nuclear Information System (INIS)

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

    1975-01-01

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

  16. Devices and process for high-pressure magic angle spinning nuclear magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Hoyt, David W.; Sears, Jesse A.; Turcu, Romulus V. F.; Rosso, Kevin M.; Hu, Jian Zhi

    2017-12-05

    A high-pressure magic angle spinning (MAS) rotor is detailed that includes a high-pressure sample cell that maintains high pressures exceeding 150 bar. The sample cell design minimizes pressure losses due to penetration over an extended period of time.

  17. Devices and process for high-pressure magic angle spinning nuclear magnetic resonance

    Science.gov (United States)

    Hoyt, David W; Sears, Jr., Jesse A; Turcu, Romulus V.F.; Rosso, Kevin M; Hu, Jian Zhi

    2014-04-08

    A high-pressure magic angle spinning (MAS) rotor is detailed that includes a high-pressure sample cell that maintains high pressures exceeding 150 bar. The sample cell design minimizes pressure losses due to penetration over an extended period of time.

  18. 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.

  19. Paramagnetic susceptibility of the Zr{sub 62}Cu{sub 22}Al{sub 10}Fe{sub 5}Dy{sub 1} metallic glass subjected to high-pressure torsion deformation

    Energy Technology Data Exchange (ETDEWEB)

    Korolev, A.V., E-mail: korolyov@imp.uran.ru [Institute of Metal Physics of the Ural Branch RAS, Ekaterinburg (Russian Federation); Ural Federal University, Ekaterinburg (Russian Federation); Kourov, N.I. [Institute of Metal Physics of the Ural Branch RAS, Ekaterinburg (Russian Federation); Pushin, V.G. [Institute of Metal Physics of the Ural Branch RAS, Ekaterinburg (Russian Federation); Ural Federal University, Ekaterinburg (Russian Federation); Gunderov, D.V. [Saint-Petersburg State University, Saint-Petersburg (Russian Federation); Ufa State Aviation Technical University, Ufa (Russian Federation); Boltynjuk, E.V.; Ubyivovk, E.V. [Saint-Petersburg State University, Saint-Petersburg (Russian Federation); Valiev, R.Z. [Saint-Petersburg State University, Saint-Petersburg (Russian Federation); Ufa State Aviation Technical University, Ufa (Russian Federation)

    2017-09-01

    Highlights: • Zr-based BMG was subjected to HPT at temperatures of 20 °C and 150 °C. • Magnetic measurements reveal well recordable changes in paramagnetic susceptibility. • Paramagnetic susceptibility may be an indicator of a change in the structural state. - Abstract: The Zr{sub 62}Cu{sub 22}Al{sub 10}Fe{sub 5}Dy{sub 1} bulk metallic glass is studied in the as-cast state and in the state after processing by high-pressure torsion at temperatures of 20 °C and 150 °C. According to the data from X-ray diffraction and transmission electron microscopy, the structural state of the samples depends weakly on the conducted processing. At the same time, magnetic measurements reveal well recordable changes in paramagnetic susceptibility induced by the processing of the samples. It is assumed that, because of high-pressure torsion deformation, there occurs a noticeable change in the material electronic structure, which leads to a change in the full susceptibility of the samples. The performed studies demonstrate that paramagnetic susceptibility may be an indicator of a change in the structural state of paramagnetic amorphous metallic substances.

  20. High pressure structural and magnetic studies of LaFe.sub.12./sub.B.sub.6./sub.

    Czech Academy of Sciences Publication Activity Database

    Diop, L.V.B.; Isnard, O.; Arnold, Zdeněk; Itié, J.P.; Kaštil, Jiří; Kamarád, Jiří

    2017-01-01

    Roč. 252, Feb (2017), s. 29-32 ISSN 0038-1098 R&D Projects: GA ČR GA15-03777S Institutional support: RVO:68378271 Keywords : itinerant-electron magnetism * magnetization * high pressure * compressibility Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.554, year: 2016

  1. 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.

  2. Development of an extraction type magnetometer under high pressure and high magnetic fields over 200 kOe in the hybrid magnet

    International Nuclear Information System (INIS)

    Koyama, K; Miura, S; Okada, H; Watanabe, K

    2006-01-01

    An extraction-type magnetometer has been developed, which is performed under pressures up to 12 kbar using a miniature high-pressure clamp-cell, in magnetic fields up to 270 kOe using our hybrid magnet and at the temperature range from 1.5 to 300 K. Magnetization curves can be measured for absolute value over 0.04 emu. We confirmed that resolution is about ±0.01 emu under high pressures and high magnetic fields if a sample has the magnetic moment of about 3 emu. For demonstrating the ability of the instrument, high field magnetization curves for SmMn 2 Ge 2 under high pressures are presented

  3. Short review of high-pressure crystal growth and magnetic and electrical properties of solid-state osmium oxides

    Energy Technology Data Exchange (ETDEWEB)

    Yamaura, Kazunari, E-mail: YAMAURA.Kazunari@nims.go.jp [Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Graduate School of Chemical Sciences and Engineering, Hokkaido University, North 10 West 8, Kita-ku, Sapporo, Hokkaido 060-0810 (Japan)

    2016-04-15

    High-pressure crystal growth and synthesis of selected solid-state osmium oxides, many of which are perovskite-related types, are briefly reviewed, and their magnetic and electrical properties are introduced. Crystals of the osmium oxides, including NaOsO{sub 3}, LiOsO{sub 3}, and Na{sub 2}OsO{sub 4}, were successfully grown under high-pressure and high-temperature conditions at 6 GPa in the presence of an appropriate amount of flux in a belt-type apparatus. The unexpected discovery of a magnetic metal–insulator transition in NaOsO{sub 3}, a ferroelectric-like transition in LiOsO{sub 3}, and high-temperature ferrimagnetism driven by a local structural distortion in Ca{sub 2}FeOsO{sub 6} may represent unique features of the osmium oxides. The high-pressure and high-temperature synthesis and crystal growth has played a central role in the development of solid-state osmium oxides and the elucidation of their magnetic and electronic properties toward possible use in multifunctional devices. - Graphical Abstract: Flux-grown crystals of NaOsO{sub 3} under high-pressure and high-temperature conditions in a belt-type apparatus. The crystal shows a magnetically driven metal–insulator transition at a temperature of 410 K. - Highlights: • Short review of high-pressure crystal growth of solid-state osmium oxides. • Wide variety of magnetic properties of solid-state osmium oxides. • Perovskite and related dense structures stabilized at 3–17 GPa.

  4. High-pressure electron-resonance studies of electronic, magnetic, and structural phase transitions. Progress report

    International Nuclear Information System (INIS)

    Pifer, J.H.; Croft, M.C.

    1983-01-01

    Research is described in development of a high-pressure electron-resonance probe capable of operating down to 1.5 0 K temperatures. The apparatus has been used to measure the EPR of a sample of DPPH at room temperature and zero pressure. EPR has been used to measure valence field instabilities in alloy systems. Studies have been done on metal-insulator transitions at high pressure, and are briefly described

  5. Microstructure and Properties of Cobalt-and Zinc-Containing Magnetic Magnesium Alloys Processed by High-Pressure Die Casting

    Science.gov (United States)

    Klose, Christian; Demminger, Christian; Maier, Hans Jürgen

    The inherent magnetic properties of lightweight alloys based on magnesium and cobalt offer a novel way in order to measure mechanical loads throughout the entire structural component using the magnetoelastic effect. Because the solubility of cobalt in the magnesium matrix is negligible, the magnetic properties mainly originate from Co-rich precipitates. Thus, the size and distribution of Co-containing phases within the alloy's microstructure wields a major influence on the amplitude of the load-sensitive properties which can be measured by employing the harmonic analysis of eddy-current signals. In this study, Mg-Co-based alloys are produced by several casting methods which allow the application of different cooling rates, e.g. gravity die casting and high-pressure die casting. The differences between the manufactured alloys' micro- and phase structures are compared depending on the applied cooling rate and the superior magnetic and mechanical properties of the high-pressure die cast material are demonstrated.

  6. 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)

  7. 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.

  8. High-Pressure Thermodynamic Properties of f-electron Metals, Transition Metal Oxides, and Half-Metallic Magnets

    International Nuclear Information System (INIS)

    Richard T. Scalettar; Warren E. Pickett

    2005-01-01

    This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal metal to one in which only a single spin specie can conduct. Three main thrusts are being pursued: (1) Mott transitions in transition metal oxides, (2) magnetism in half-metallic compounds, and (3) large volume-collapse transitions in f-band metals

  9. High-Pressure Thermodynamic Properties of f-electron Metals, Transition Metal Oxides, and Half-Metallic Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Scalettar, Richard T.; Pickett, Warren E.

    2004-07-01

    This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal metal to one in which only a single spin specie can conduct. Three main thrusts are being pursued: (1) Mott transitions in transition metal oxides, (2) magnetism in half-metallic compounds, and (3) large volume-collapse transitions in f-band metals.

  10. High-Pressure Thermodynamic Properties of f-electron Metals, Transition Metal Oxides, and Half-Metallic Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Richard T. Scalettar; Warren E. Pickett

    2005-08-02

    This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal metal to one in which only a single spin specie can conduct. Three main thrusts are being pursued: (i) Mott transitions in transition metal oxides, (ii) magnetism in half-metallic compounds, and (iii) large volume-collapse transitions in f-band metals.

  11. 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

  12. 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

  13. Susceptibility effects in nuclear magnetic resonance imaging

    International Nuclear Information System (INIS)

    Ziener, Christian Herbert

    2008-01-01

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

  14. Magnetic susceptibility measurements on Bi - Sn alloys

    International Nuclear Information System (INIS)

    Mustaffa bin Haji Abdullah

    1985-01-01

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

  15. 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

  16. A beamline for high-pressure studies at the Advanced Light Source with a superconducting bending magnet as the source.

    Science.gov (United States)

    Kunz, Martin; MacDowell, Alastair A; Caldwell, Wendel A; Cambie, Daniella; Celestre, Richard S; Domning, Edward E; Duarte, Robert M; Gleason, Arianna E; Glossinger, James M; Kelez, Nicholas; Plate, David W; Yu, Tony; Zaug, Joeseph M; Padmore, Howard A; Jeanloz, Raymond; Alivisatos, A Paul; Clark, Simon M

    2005-09-01

    A new facility for high-pressure diffraction and spectroscopy using diamond anvil high-pressure cells has been built at the Advanced Light Source on beamline 12.2.2. This beamline benefits from the hard X-radiation generated by a 6 T superconducting bending magnet (superbend). Useful X-ray flux is available between 5 keV and 35 keV. The radiation is transferred from the superbend to the experimental enclosure by the brightness-preserving optics of the beamline. These optics are comprised of a plane parabola collimating mirror, followed by a Kohzu monochromator vessel with Si(111) crystals (E/DeltaE approximately equal 7000) and W/B4C multilayers (E/DeltaE approximately equal 100), and then a toroidal focusing mirror with variable focusing distance. The experimental enclosure contains an automated beam-positioning system, a set of slits, ion chambers, the sample positioning goniometry and area detector (CCD or image-plate detector). Future developments aim at the installation of a second endstation dedicated to in situ laser heating and a dedicated high-pressure single-crystal station, applying both monochromatic and polychromatic techniques.

  17. Moessbauer investigation of magnetic hyperfine fields near bivalent Eu compounds under high pressure

    International Nuclear Information System (INIS)

    Abd Elmeguid, M.

    1979-01-01

    The paper deals with the pressure or volume dependence of hyperfine interactions of magnetically ordered, bivalent europium compounds. Emphasis is laid on the investigation of the pressure or volume dependence of magnetic hyperfine fields as they are found at the nuclear site of 151 Eu or of diamagnetic 119 Sn or 197 Au probe atoms. The measurements were carried out with the aid of the gamma resonance of 151 Eu (21.6 keV) 119 Sn (23.8 keV) and 167 Au (77.4 keV) at low temperatures and external pressures up to 65 kbar. (orig./WBU) [de

  18. Development of high pressure magnetic force drive seal for commercial purpose

    International Nuclear Information System (INIS)

    Choi, Jong Hyeun; Hwang, S. T.; Choi, Y. D.; Kwon, S. W.; Kim, B. H.; Eo, H.; Lee, K. H.; Kim, J. K.; Jun, S. W.

    1999-12-01

    The purpose of this research is to develop and commercialize the magnetic seal which is used as a axis-sealing or connecting apparatus in the rotating machines where the liquid should not be leaked, instead of the existing mechanical seal. The developed magnetic seal will be applied in the rotating machine such as agitators and so on. In present, four institutes including Machinery Institute have purchased and using the agitators which applied the developed seal and have a good reputation. The existing mechanical seals a lot of which are used in the industry, has a complex structure, short-lifetime. And also, they are expensive and not leak-free. On the other hand, the developed magnetic seals have simple structure, low-cost, long-lifetime, and no-leakage. So these seals can be used most appropriately in the facilities which deal with dangerous and anti-environmental materials. And technical and economical effects of the magnetics seals will be expected. (author)

  19. 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

  20. Synthesis of nanoparticles using high-pressure sputtering for magnetic domain imaging

    International Nuclear Information System (INIS)

    Shah, Prasanna; Gavrin, A.

    2006-01-01

    We have developed a modified sputtering gun for direct synthesis of metallic nanoparticles, and used this system to produce magnetic domain images using high-resolution Bitter microscopy (HRBM). The nanoparticles are produced at 900 mTorr inside the gun and transported to the main vacuum chamber by the pressure difference between the chamber and the gun interior. Fe particles synthesized using the particle gun have been characterized using X-ray diffraction, atomic force microscopy, and transmission electron microscopy techniques. The particles are 15-30 nm in size with a pure BCC phase. Further, we have deposited these Fe nanoparticles on magnetic recording media and observed the domain patterns using optical microscopy, scanning electron microscopy, and atomic force microscopy. We achieve a spatial resolution of at most 80 nm

  1. Magnetic measurements of superconducting LiFeAs single crystals under high pressure

    Science.gov (United States)

    Miyoshi, Kiyotaka; Otsuka, Keisuke; Ogawa, Saki; Takeuchi, Jun

    2018-05-01

    Measurements of DC magnetization for single crystal specimens of LiFeAs have been performed under pressure using liquid argon and NaCl as pressure transmitting media (PTM) to generate hydrostatic and nearly uniaxial pressure along c-axis, respectively. It has been found that Tc linearly decreases under pressure with pressure coefficient dTc / dP ∼ - 1.6 - 1.7 K/GPa, and then shows a pressure independent behavior with Tc ∼ 8 K above 5 GPa. These behaviors are observed independently of whether we select liquid argon or NaCl as PTM. This suggests that c-axis lattice constant is not an important factor to determine Tc in LiFeAs, in contrast to KxFe2-ySe2 and (NH3)yAxFe2Se2 (A=alkali metal).

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

    International Nuclear Information System (INIS)

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

    1977-01-01

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

  3. Extraordinary magnetic and structural properties of the off-stoichiometric and the Co-doped Ni.sub.2./sub.MnGa Heusler alloys under high pressure

    Czech Academy of Sciences Publication Activity Database

    Kamarád, Jiří; Albertini, F.; Arnold, Zdeněk; Fabbrici, S.; Kaštil, Jiří

    2014-01-01

    Roč. 77, Sep (2014), s. 60-67 ISSN 1359-6454 R&D Projects: GA ČR GAP204/12/0692 Institutional support: RVO:68378271 Keywords : Heusler alloys * martensitic transformation * magnetic properties * high pressure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.465, year: 2014

  4. Collapse of ferromagnetism in itinerant-electron system: a magnetic, transport properties, and high pressure study of (Hf,Ta)Fe.sub.2./sub. compounds

    Czech Academy of Sciences Publication Activity Database

    Diop, L.; Kaštil, Jiří; Isnard, O.; Arnold, Zdeněk; Kamarád, Jiří

    2014-01-01

    Roč. 116, č. 16 (2014), "163907-1"-"163907-10" ISSN 0021-8979 R&D Projects: GA ČR GAP204/12/0692 Institutional support: RVO:68378271 Keywords : high pressure * magnetic properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.183, year: 2014

  5. Magnetic susceptibility of YbN

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  6. Acoustic investigation of magnetic susceptibility of liquid metals

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  7. 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.

  8. 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 ...

  9. 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.

  10. High pressure studies of magnetic, electronic, and local structure properties in the rare-earth orthoferrites RFeO3 (R = Nd, Lu)

    International Nuclear Information System (INIS)

    Gavriliuk, A.G.; Stepanov, G.N.; Lyubutin, I.S.; Stepin, A.S.; Trojan, I.A.; Sidorov, V.A.

    2000-01-01

    The high pressure modification of the electronic structure, magnetic properties, and local crystal structure have been studied in the rare-earth RFeO 3 (R=Nd, Lu) orthoferrites in both pure single crystals and polycrystalline samples doped with Sn. The pressure dependences of the unit cell parameters, Neel temperatures, supertransferred hyperfine magnetic fields at tin nuclei H Sn , and the optical absorption edge have been obtained. The relations of the obtained values with the geometry of exchange interactions were analyzed

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

    International Nuclear Information System (INIS)

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

    1975-07-01

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

  12. High-frequency, transient magnetic susceptibility of ferroelectrics

    Science.gov (United States)

    Grimes, Craig A.

    1996-10-01

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

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

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  14. High-pressure, high-temperature magic angle spinning nuclear magnetic resonance devices and processes for making and using same

    Science.gov (United States)

    Hu, Jian Zhi; Hu, Mary Y.; Townsend, Mark R.; Lercher, Johannes A.; Peden, Charles H. F.

    2015-10-06

    Re-usable ceramic magic angle spinning (MAS) NMR rotors constructed of high-mechanic strength ceramics are detailed that include a sample compartment that maintains high pressures up to at least about 200 atmospheres (atm) and high temperatures up to about least about 300.degree. C. during operation. The rotor designs minimize pressure losses stemming from penetration over an extended period of time. The present invention makes possible a variety of in-situ high pressure, high temperature MAS NMR experiments not previously achieved in the prior art.

  15. 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.

  16. Effect of centrifugation on dynamic susceptibility of magnetic fluids

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-06-15

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

  17. Material properties of Ni-Cr-Al alloy and design of a 4 GPa class non-magnetic high-pressure cell

    CERN Document Server

    Uwatoko, Y; Ueda, K; Uchida, A; Kosaka, M; Mori, N; Matsumoto, T

    2002-01-01

    The Ni-Cr-Al Russian alloy was prepared. Its magnetic and mechanical properties were better than those of MP35N alloy. We fabricated the a piston-cylinder-type hybrid high-pressure cell using the Ni-Cr-Al alloy. It has been found that the maximum working pressure can be repeatedly raised to 3.5 GPa at T = 2 K without any difficulties.

  18. Soil magnetic susceptibility as indicator of radioactive contamination

    International Nuclear Information System (INIS)

    Curda, S.

    2006-01-01

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

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

    NARCIS (Netherlands)

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

    2006-01-01

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

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

    International Nuclear Information System (INIS)

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

    1978-01-01

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

  1. Study of magnetic, structural and magnetocaloric properties of La.sub.0.6./sub.Pr.sub.0.4./sub.Mn.sub.2./sub.Si.sub.2./sub. under high pressures and magnetic field

    Czech Academy of Sciences Publication Activity Database

    Kaštil, Jiří; Arnold, Zdeněk; Isnard, O.; Skourski, Y.; Kamarád, Jiří; Itié, J.P.

    2017-01-01

    Roč. 424, Feb (2017), s. 416-420 ISSN 0304-8853 R&D Projects: GA ČR GA15-03777S Institutional support: RVO:68378271 Keywords : magnetization * compressibility * magnetocaloric effect * high pressure Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.630, year: 2016

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

    International Nuclear Information System (INIS)

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

    1987-01-01

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

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

    International Nuclear Information System (INIS)

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

    1976-01-01

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

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

    Science.gov (United States)

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

    2017-11-01

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

  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. High pressure synthesis and magnetic studies of quasi one dimensional systems Sr{sub n-1} Cu{sub n+1} O{sub 2n} (n=3,5)

    Energy Technology Data Exchange (ETDEWEB)

    Azuma, M.; Hiroi, Z.; Takano, M. [Kyoto Univ. (Japan)] [and others

    1994-12-31

    SrCu{sub 2}O{sub 3} and Sr{sub 2}Cu{sub 3}O{sub 5} containing two-leg and three-leg S=1/2 ladders made of antiferromagnetic Cu-O-Cu linear bonds, respectively, were synthesized at high pressure, and their crystallographic and magnetic properties were investigated. Both susceptibility and T{sub 1} data of NMR revealed the existence of a large spin gap only for SrCu{sub 2}O{sub 3}. Superconductivity, which had been predicted theoretically for carrier-doped SrCu{sub 2}O{sub 3} could not be realized although partial substitution of La{sup 3+} for Sr{sup 2+} seemed to be carried out successfully. Electron carriers injected seems to remain localized.

  8. High pressure phase transition and anharmonic properties of Zn1-xMxSe (M=Cd, Fe and Mn) diluted magnetic semiconductor

    International Nuclear Information System (INIS)

    Talati, Mina; Shinde, Satyam; Jha, Prafulla K.

    2004-01-01

    The present work employs interionic potential approach based on charge transfer effect to calculate and describe the high pressure phase transition and elastic behaviour of the diluted magnetic semiconductors Zn 1-x M x Se (M=Cd, Fe and Mn). We have obtained a reasonably good agreement between present calculated values and experimentally observed data on the phase transition pressures. The volume collapses and high pressure behaviours are also in reasonably good agreement with the available data for all compounds under consideration. The variations of elastic constants and their combinations with pressure follow a systematic trend, identical to that observed in other compounds of zinc blende structure family. The present approach has also succeeded in predicting the Born and relative stability criteria

  9. Study of the magnetic susceptibilities of some plutonium derivatives

    International Nuclear Information System (INIS)

    Raphael, G.

    1969-06-01

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

  10. High-pressure crystal growth and magnetic and electrical properties of the quasi-one dimensional osmium oxide Na2OsO4

    International Nuclear Information System (INIS)

    Shi, Y.G.; Guo, Y.F.; Yu, S.; Arai, M.; Belik, A.A.; Sato, A.; Yamaura, K.; Takayama-Muromachi, E.

    2010-01-01

    Na 2 OsO 4 crystals were grown by a NaCl flux method under high pressure. It crystallizes in the Ca 2 IrO 4 -type structure without having additional elements or metal vacancies, which are usually accommodated. It appears that Na 2 OsO 4 is a metal-stoichiometric Ca 2 IrO 4 -type compound never been synthesized to date. Na 2 OsO 4 has the octahedral environment of Os 6+ O 6 so that the electronic configuration is 5d 2 , suggesting the magnetic S=1 ground state. However, magnetization, electrical resistivity, and specific heat measurements indicated that the non-magnetic S=0 state is much likely for Na 2 OsO 4 than the S=1 state. Band structure calculations and the structure analysis found that the disagreement is probably due to the statically uniaxial compression of the OsO 6 octahedra, resulting in splitting of the t 2 g band. - Graphical abstract: Na 2 OsO 4 crystals were grown by a NaCl flux method under high pressure. It crystallizes in the Ca 2 IrO 4 -type structure comprising infinite Os 6+ O 6 octahedra (5d 2 ) chains. The crystal growth, the crystal structure, and the magnetic and electrical properties are reported.

  11. 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.

  12. 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.

  13. 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.

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

    International Nuclear Information System (INIS)

    Welter, J.-M.

    1983-01-01

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

  15. Phase separation, effects of magnetic field and high pressure on charge ordering in γ-Na0.5CoO2

    International Nuclear Information System (INIS)

    Yang, H.X.; Shi, Y.G.; Nie, C.J.; Wu, D.; Yang, L.X.; Dong, C.; Yu, H.C.; Zhang, H.R.; Jin, C.Q.; Li, J.Q.

    2005-01-01

    Transmission electron microscopy (TEM) observations reveal the presence of complex superstructures and remarkable phase separation in association with Na-ordering phenomenon in γ-Na 0.5 CoO 2 . Resistivity and magnetization measurements indicate that three phase transitions at the temperatures of 25, 53 and 90 K, respectively, appear commonly in γ-Na 0.5 CoO 2 samples. Under a high pressure up to 10 kbar, the low-temperature transport properties show certain changes below the charge order transition; under an applied magnetic field of 7 T, phase transitions at around 25 and 53 K, proposed fundamentally in connection with alternations of magnetic structure and charge ordering maintain almost unchanged

  16. Fabrication of High-performance Sm-Fe-N isotropic bulk magnets by a combination of High-pressure compaction and current sintering

    Energy Technology Data Exchange (ETDEWEB)

    Takagi, Kenta, E-mail: k-takagi@aist.go.jp [Materials Research Institute for Sustainable Development, National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560 (Japan); Nakayama, Hiroyuki; Ozaki, Kimihiro; Kobayashi, Keizo [Materials Research Institute for Sustainable Development, National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560 (Japan)

    2012-04-15

    TbCu{sub 7}-type Sm-Fe-N coarse powders in the flake form were consolidated without a bonding medium using a low-thermal-load process of current sintering combined with high-pressure compression. When compacted at 1.2 GPa, the relative density of the powder was increased by 80% with close stacking of the flake particles. Although the subsequent current heating was only briefly performed at a low temperature of 400 Degree-Sign C to avoid decomposition, the compact was consolidated into a rigid bulk in which the particles were bonded at the atomic level. Finally, by using cyclic compaction, this process produced bulk magnets with a density of 92% that exhibited the highest maximum energy product (BH)max of 16.2 MGOe, which surpasses that of conventional isotropic Sm-Fe-N bond magnets. - Highlights: Black-Right-Pointing-Pointer We conduct a consolidation of Sm{sub 1}Fe{sub 7}N bulk magnets without thermal decomposition. Black-Right-Pointing-Pointer Rapid current sintering with high-pressure compaction is used as a low-thermal-load process. Black-Right-Pointing-Pointer In this process, sintering occurs at a temperature of 400 Degree-Sign C, which is below the decomposition point. Black-Right-Pointing-Pointer As a result, bulk magnets with a density of over 92% are obtained without decomposition. Black-Right-Pointing-Pointer These magnets exhibit the highest (BH)max (16.2 MGOe) among isotropic Sm-Fe-N magnets.

  17. Magnetically applied pressure-shear : a new technique for direct strength measurement at high pressure (final report for LDRD project 117856).

    Energy Technology Data Exchange (ETDEWEB)

    Lamppa, Derek C.; Haill, Thomas A.; Alexander, C. Scott; Asay, James Russell

    2010-09-01

    A new experimental technique to measure material shear strength at high pressures has been developed for use on magneto-hydrodynamic (MHD) drive pulsed power platforms. By applying an external static magnetic field to the sample region, the MHD drive directly induces a shear stress wave in addition to the usual longitudinal stress wave. Strength is probed by passing this shear wave through a sample material where the transmissible shear stress is limited to the sample strength. The magnitude of the transmitted shear wave is measured via a transverse VISAR system from which the sample strength is determined.

  18. AC susceptibility enhancement studies in magnetic systems

    International Nuclear Information System (INIS)

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

    2001-01-01

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

  19. Magnetic susceptibility measuring probe utilizing a compensation coil

    International Nuclear Information System (INIS)

    Bonnet, Jean; Fournet, Julien.

    1978-01-01

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

  20. Crystal structure and magnetic susceptibility of UOSe single crystals

    International Nuclear Information System (INIS)

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

    1993-01-01

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

  1. Crystal structure and magnetic susceptibility of UOSe single crystals

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-01-01

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

  2. 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.

  3. Magnetic properties of GdCo.sub.12./sub. B.sub.6./sub. compound under high pressures

    Czech Academy of Sciences Publication Activity Database

    Arnold, Zdeněk; Isnard, O.; Mayot, H.; Skorokhod, Yuriy; Kamarád, Jiří; Míšek, Martin

    2012-01-01

    Roč. 152, č. 13 (2012), s. 1164-1167 ISSN 0038-1098 R&D Projects: GA ČR GA202/09/1027 Institutional research plan: CEZ:AV0Z10100521 Keywords : borides * magnetic properties * compensation temperature * pressure effect Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.534, year: 2012 http://dx.doi.org/10.1016/j.ssc.2012.03.038

  4. Anisotropic magnetic structures of the Mn R MnSbO6 high-pressure doubly ordered perovskites (R =La , Pr, and Nd)

    Science.gov (United States)

    Solana-Madruga, Elena; Arévalo-López, Ángel M.; Dos santos-García, Antonio J.; Ritter, Clemens; Cascales, Concepción; Sáez-Puche, Regino; Attfield, J. Paul

    2018-04-01

    A new type of doubly ordered perovskite (also reported as double double perovskite, DDPv) structure combining columnar and rock-salt orders of the cations at the A and B sites, respectively, was recently found at high pressure for Mn R MnSb O6 (R =La -Sm ). Here we report further magnetic structures of these compounds. M n2 + spins align into antiparallel ferromagnetic sublattices along the x axis for MnLaMnSb O6 , while the magnetic anisotropy of P r3 + magnetic moments induces their preferential order along the z direction for MnPrMnSb O6 . The magnetic structure of MnNdMnSb O6 was reported to show a spin-reorientation transition of M n2 + spins from the z axis towards the x axis driven by the ordering of N d3 + magnetic moments. The crystal-field parameters for P r3 + and N d3 + at the 4 e C2 site of their DDPv structure have been semiempirically estimated and used to derive their energy levels and associated wave functions. The results demonstrate that the spin-reorientation transition in MnNdMnSb O6 arises as a consequence of the crystal-field-induced magnetic anisotropy of N d3 + .

  5. 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

  6. Magnetic irreversibility in granular superconductors: ac susceptibility study

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  7. Pure-iron/iron-based-alloy hybrid soft magnetic powder cores compacted at ultra-high pressure

    Science.gov (United States)

    Saito, Tatsuya; Tsuruta, Hijiri; Watanabe, Asako; Ishimine, Tomoyuki; Ueno, Tomoyuki

    2018-04-01

    We developed Fe/FeSiAl soft magnetic powder cores (SMCs) for realizing the miniaturization and high efficiency of an electromagnetic conversion coil in the high-frequency range (˜20 kHz). We found that Fe/FeSiAl SMCs can be formed with a higher density under higher compaction pressure than pure-iron SMCs. These SMCs delivered a saturation magnetic flux density of 1.7 T and iron loss (W1/20k) of 158 kW/m3. The proposed SMCs exhibited similar excellent characteristics even in block shapes, which are closer to the product shapes.

  8. Pure-iron/iron-based-alloy hybrid soft magnetic powder cores compacted at ultra-high pressure

    Directory of Open Access Journals (Sweden)

    Tatsuya Saito

    2018-04-01

    Full Text Available We developed Fe/FeSiAl soft magnetic powder cores (SMCs for realizing the miniaturization and high efficiency of an electromagnetic conversion coil in the high-frequency range (∼20 kHz. We found that Fe/FeSiAl SMCs can be formed with a higher density under higher compaction pressure than pure-iron SMCs. These SMCs delivered a saturation magnetic flux density of 1.7 T and iron loss (W1/20k of 158 kW/m3. The proposed SMCs exhibited similar excellent characteristics even in block shapes, which are closer to the product shapes.

  9. Magnetization and neutron diffraction studies of Lu.sub.2./sub.Fe.sub.17./sub. under high pressure

    Czech Academy of Sciences Publication Activity Database

    Kamarád, Jiří; Prokhnenko, Olexandr; Prokeš, K.; Arnold, Zdeněk

    2005-01-01

    Roč. 17, - (2005), S3069-S3075 ISSN 0953-8984 R&D Projects: GA ČR(CZ) GP202/04/P014; GA ČR(CZ) GA202/02/0739 Grant - others:European Commission(XE) RII3-CT-2003-505925 (NMI3) Institutional research plan: CEZ:AV0Z10100521 Keywords : intermetallic compounds * neutron diffraction * pressure effect * helimagnetic structure * magnetic phase transitions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.145, year: 2005

  10. 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 ...

  11. 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 ...

  12. Susceptibility and magnetization of a random Ising model

    Energy Technology Data Exchange (ETDEWEB)

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

    1977-08-01

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

  13. 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

  14. 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…

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  16. Magnetic susceptibility of molecular carbon: nanotubes and fullerite

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-07-01

    Elemental carbon can be synthesized in a variety of geometrical forms, from three-dimensional extended structures (diamond) to finite molecules (C[sub 60] fullerite). Results are presented here on the magnetic susceptibility of the least well-understood members of this family, nanotubes and C[sub 60] fullerite. (1) Nanotubes represent the cylindrical form of carbon, intermediate between graphite and fullerite. They are found to have significantly larger orientation-averaged susceptibility, on a per carbon basis, than any other form of elemental carbon. This susceptibility implies an average band structure among nanotubes similar to that of graphite. (2) High-resolution magnetic susceptibility data on C[sub 60] fullerite near the molecular orientational-ordering transition at 259 K show a sharp jump corresponding to 2.5 centimeter-gram-second parts per million per mole of C[sub 60]. This jump directly demonstrates the effect of an intermolecular cooperative transition on an intramolecular electronic property, where the susceptibility jump may be ascribed to a change in the shape of the molecule due to lattice forces.

  17. The nature of transport critical current hysteresis in HTSC: magnetic fields and high pressures. [Y-Ba-Cu-O

    Energy Technology Data Exchange (ETDEWEB)

    Svistunov, V M; Yachenko, A.I. d' ; Tarenkov, V Yu [Donetsk Physico-Technical Inst., Ukrainian SSR (USSR)

    1991-12-01

    It was found that pressure has a strong influence on the critical current hysteresis loop of ceramics at H {proportional to} 10 kOe. The phenomenon is attributed to the critical current hysteresis of separate Josephson contacts and is due to the Abrikosov vortex density gradient within granules. The gradient defines both the sign and the value of the pinning current, whereas the sign of Meissner reversible surfaces current component is determined by the external field H direction. As a result the critical current of Josephson contacts defined by the total surface value depends on the magnetic prehistory of a sample. (orig.).

  18. 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)

  19. High-pressure apparatus

    NARCIS (Netherlands)

    Schepdael, van L.J.M.; Bartels, P.V.; Berg, van den R.W.

    1999-01-01

    The invention relates to a high-pressure device (1) having a cylindrical high-pressure vessel (3) and prestressing means in order to exert an axial pressure on the vessel. The vessel (3) can have been formed from a number of layers of composite material, such as glass, carbon or aramide fibers which

  20. High-pressure crystallography

    Science.gov (United States)

    Katrusiak, A.

    2008-01-01

    The history and development of high-pressure crystallography are briefly described and examples of structural transformations in compressed compounds are given. The review is focused on the diamond-anvil cell, celebrating its 50th anniversary this year, the principles of its operation and the impact it has had on high-pressure X-ray diffraction.

  1. 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

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

    Science.gov (United States)

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

    2015-01-01

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

  3. Quantitative interpretation of the magnetic susceptibility frequency dependence

    Science.gov (United States)

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

    2018-05-01

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

  4. 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

  5. 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

  6. Structural and magnetic phase transitions in Pr.sub.0.15./sub.Sr.sub.0.85./sub.MnO.sub.3./sub. at high pressure

    Czech Academy of Sciences Publication Activity Database

    Kozlenko, D. P.; Dang, N.T.; Jirák, Zdeněk; Kichanov, S.E.; Lukin, E.V.; Savenko, B. N.; Dubrovinsky, L.S.; Lathe, C.; Martin, C.

    2010-01-01

    Roč. 77, č. 3 (2010), s. 407-411 ISSN 1434-6028 Institutional research plan: CEZ:AV0Z10100521 Keywords : high pressure * magnetic phase transitions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.575, year: 2010

  7. Experimental Investigation of Magnetic Superconducting, and other Phase Transitions in Novel f-Electron Materials at Ultra-high Pressures Using Designer Diamond Anvils

    International Nuclear Information System (INIS)

    Maple, M. Brian

    2005-01-01

    Pressure is a powerful control parameter, owing to its ability to affect crystal and electronic structure without introducing defects, for the investigation of condensed matter systems. Some f-electron, heavy-fermion materials display interesting and novel behavior when exposed to pressures achievable with conventional experimental techniques; however, a growing number of condensed matter systems require extreme conditions such as ultrahigh pressures, high magnetic fields, and ultralow temperatures to sufficiently explore the important properties. To that end, we have been funded to develop an ultrahigh pressure facility at the University of California, San Diego (UCSD) in order to investigate superconductivity, magnetism, non-Fermi liquid behavior, and other phenomena under extreme conditions. Our goals for the second year of this grant were as follows: (a) perform electrical resistivity measurements on novel samples at a myriad of pressures using conventional piston-cylinder techniques, Bridgman anvil techniques, and diamond anvil cell technology; (b) install, commission, and operate an Oxford Kelvinox MX-100 dilution refrigerator for access to ultralow temperatures and high magnetic fields. (c) continue the development of diamond anvil cell (DAC) technology. During the past year, we have successfully installed the Oxford Kelvinox MX-100 dilution refrigerator and verified its operability down to 12 mK. We have begun an experimental program to systematically investigate the f-electron compound URu2Si2 under pressure and in the presence of magnetic fields. We have also continued our collaborative work with Sam Weir at Lawrence Livermore National Laboratory (LLNL) on Au4V and implemented a new corollary study on Au1-xVx using ultrahigh pressures. We have continued developing our DAC facility by designing and constructing an apparatus for in situ pressure measurement as well as designing high pressure cells. This report serves to highlight the progress we have made

  8. High-pressure tritium

    International Nuclear Information System (INIS)

    Coffin, D.O.

    1976-01-01

    Some solutions to problems of compressing and containing tritium gas to 200 MPa at 700 0 K are discussed. The principal emphasis is on commercial compressors and high-pressure equipment that can be easily modified by the researcher for safe use with tritium. Experience with metal bellows and diaphragm compressors has been favorable. Selection of materials, fittings, and gauges for high-pressure tritium work is also reviewed briefly

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

    International Nuclear Information System (INIS)

    Mejdani, R.

    1993-05-01

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

  10. Perfusion imaging with magnetic-susceptibility contrast media

    International Nuclear Information System (INIS)

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

    1989-01-01

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

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

    National Research Council Canada - National Science Library

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

    2003-01-01

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

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

    International Nuclear Information System (INIS)

    Kawamori, E

    2011-01-01

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

  13. Magnetic properties of LaCo.sub.12./sub. B.sub.6./sub. compound as probed by neutron diffraction and by magnetization study under high pressures

    Czech Academy of Sciences Publication Activity Database

    Diop, L.V.B.; Arnold, Zdeněk; Isnard, O.; Kamarád, Jiří

    2014-01-01

    Roč. 593, APR (2014), s. 163-168 ISSN 0925-8388 R&D Projects: GA ČR GA202/09/1027 Institutional support: RVO:68378271 Keywords : pressure effect * borides * magnetic properties * neutron diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.999, year: 2014

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

    International Nuclear Information System (INIS)

    Collings, E.W.

    1979-01-01

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

  15. Experimental Investigation of Magnetic Superconducting and other Phase Transitions in Novel f-Electron Materials at Ultra-high Pressures using Designer Diamond Anvils

    International Nuclear Information System (INIS)

    Maple, M. Brian; Jeffries, Jason R.; Ho, Pei-Chun; Butch, Nicholas P.

    2004-01-01

    Pressure is often used as a controlled parameter for the investigation of condensed matter systems. In particular, pressure experiments can provide valuable information into the nature of superconductivity, magnetism, and the coexistence of these two phenomena. Some f-electron, heavy-fermion materials display interesting and novel behavior at moderately low pressures achievable with conventional experimental techniques; however, a growing number of condensed matter systems require ultrahigh pressure techniques, techniques that generate significantly higher pressures than conventional methods, to sufficiently explore their important properties. To that end, we have been funded to develop an ultrahigh pressure diamond anvil cell facility at the University of California, San Diego (UCSD) in order to investigate superconductivity, magnetism, non-Fermi liquid behavior, and other phenomena. Our goals for the first year of this grant were as follows: (a) set up and test a suitable refrigerator; (b) set up a laser and spectrometer fluorescence system to determine the pressure within the diamond anvil cell; (c) perform initial resistivity measurements at moderate pressures from room temperature to liquid helium temperatures (∼1K); (d) investigate f-electron materials within our current pressure capabilities to find candidate materials for high-pressure studies. During the past year, we have ordered almost all the components required to set up a diamond anvil cell facility at UCSD, we have received and implemented many of the components that have been ordered, we have performed low pressure research on several materials, and we have engaged in a collaborative effort with Sam Weir at Lawrence Livermore National Lab (LLNL) to investigate Au4V under ultrahigh pressure in a designer diamond anvil cell (dDAC). This report serves to highlight the progress we have made towards developing an ultrahigh pressure research facility at UCSD, the research performed in the past year, as

  16. 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.

  17. Fascination at high pressures

    International Nuclear Information System (INIS)

    Chidambaram, R.

    1992-01-01

    Research at high pressures has developed into an interdisciplinary area which has important implications for and applications in the areas of physics, chemistry, materials sciences, planetary sciences, biology, engineering sciences and technology. The state of-the-art in this field is reviewed and future directions are indicated. (M.G.B.)

  18. High Pressure Biomass Gasification

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, Pradeep K [Georgia Tech Research Corporation, Atlanta, GA (United States)

    2016-07-29

    According to the Billion Ton Report, the U.S. has a large supply of biomass available that can supplement fossil fuels for producing chemicals and transportation fuels. Agricultural waste, forest residue, and energy crops offer potential benefits: renewable feedstock, zero to low CO2 emissions depending on the specific source, and domestic supply availability. Biomass can be converted into chemicals and fuels using one of several approaches: (i) biological platform converts corn into ethanol by using depolymerization of cellulose to form sugars followed by fermentation, (ii) low-temperature pyrolysis to obtain bio-oils which must be treated to reduce oxygen content via HDO hydrodeoxygenation), and (iii) high temperature pyrolysis to produce syngas (CO + H2). This last approach consists of producing syngas using the thermal platform which can be used to produce a variety of chemicals and fuels. The goal of this project was to develop an improved understanding of the gasification of biomass at high pressure conditions and how various gasification parameters might affect the gasification behavior. Since most downstream applications of synags conversion (e.g., alcohol synthesis, Fischer-Tropsch synthesis etc) involve utilizing high pressure catalytic processes, there is an interest in carrying out the biomass gasification at high pressure which can potentially reduce the gasifier size and subsequent downstream cleaning processes. It is traditionally accepted that high pressure should increase the gasification rates (kinetic effect). There is also precedence from coal gasification literature from the 1970s that high pressure gasification would be a beneficial route to consider. Traditional approach of using thermogravimetric analyzer (TGA) or high-pressure themogravimetric analyzer (PTGA) worked well in understanding the gasification kinetics of coal gasification which was useful in designing high pressure coal gasification processes. However

  19. 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

  20. 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.

  1. 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

  2. Deuterium high pressure target

    International Nuclear Information System (INIS)

    Perevozchikov, V.V.; Yukhimchuk, A.A.; Vinogradov, Yu.I.

    2001-01-01

    The design of the deuterium high-pressure target is presented. The target having volume of 76 cm 3 serves to provide the experimental research of muon catalyzed fusion reactions in ultra-pure deuterium in the temperature range 80-800 K under pressures of up to 150 MPa. The operation of the main systems of the target is described: generation and purification of deuterium gas, refrigeration, heating, evacuation, automated control system and data collection system

  3. 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

  4. 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

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

    International Nuclear Information System (INIS)

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

    2004-01-01

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

  6. 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

  7. 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

  8. High-pressure cells for study of condensed matter by diffraction and inelastic neutron scattering at low temperatures and in strong magnetic fields

    Science.gov (United States)

    Sadykov, R. A.; Strassle, Th; Podlesnyak, A.; Keller, L.; Fak, B.; Mesot, J.

    2017-12-01

    We have developed and implemented series of new original clamp high-pressure cells for neutron diffraction and inelastic neutron scattering at low temperatures. The cells design allows one to place them in the standard cryostats or cryomagnets used on neutron sources. Some results obtained for ZnCr2Se4 are demonstrated as an example.

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  10. Effects of high pressure on the structural, magnetic, and transport properties of the itinerant 5f ferromagnet U.sub.2./sub.Fe.sub.3./sub.Ge

    Czech Academy of Sciences Publication Activity Database

    Henriques, M.S.; Gorbunov, Denis; Andreev, Alexander V.; Arnold, Zdeněk; Surblé, S.; Heathman, S.; Griveau, J.C.; Lopes, E.B.; Prchal, J.; Havela, L.; Gonçalves, A.P.

    2014-01-01

    Roč. 89, č. 5 (2014), "054407-1"-"054407-9" ISSN 1098-0121 R&D Projects: GA ČR GAP204/12/0150; GA ČR(CZ) GAP204/10/0330 Grant - others:AVČR(CZ) M100101203 Institutional support: RVO:68378271 Keywords : actinide intermetallics * ferromagnetism * magnetoelasticity * high pressure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  11. The high-pressure phase of CePtAl

    International Nuclear Information System (INIS)

    Heymann, Gunter; Heying, Birgit; Rodewald, Ute C.; Janka, Oliver; Univ. Oldenburg

    2017-01-01

    The intermetallic aluminum compound HP-CePtAl was synthesized by arc melting of the elements with subsequent high-pressure/high-temperature treatment at 1620 K and 10.5 GPa in a multianvil press. The compound crystallizes in the hexagonal MgZn_2-type structure (P6_3/mmc) with lattice parameters of a=552.7(1) and c=898.8(2) pm refined from powder X-ray diffraction data. With the help of single crystal investigations (wR=0.0527, 187 F"2 values, 13 variables), the proposed structure type was confirmed and the mixed Pt/Al site occupations could be refined. Magnetic susceptibility measurements showed a disappearance of the complex magnetic ordering phenomena, which are observed in NP-CePtAl.

  12. The high-pressure phase of CePtAl

    Energy Technology Data Exchange (ETDEWEB)

    Heymann, Gunter [Univ. Innsbruck (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie; Heying, Birgit; Rodewald, Ute C. [Univ. Muenster (Germany). Inst. fuer Anorganische und Analytische Chemie; Janka, Oliver [Univ. Muenster (Germany). Inst. fuer Anorganische und Analytische Chemie; Univ. Oldenburg (Germany). Inst. fuer Chemie

    2017-03-01

    The intermetallic aluminum compound HP-CePtAl was synthesized by arc melting of the elements with subsequent high-pressure/high-temperature treatment at 1620 K and 10.5 GPa in a multianvil press. The compound crystallizes in the hexagonal MgZn{sub 2}-type structure (P6{sub 3}/mmc) with lattice parameters of a=552.7(1) and c=898.8(2) pm refined from powder X-ray diffraction data. With the help of single crystal investigations (wR=0.0527, 187 F{sup 2} values, 13 variables), the proposed structure type was confirmed and the mixed Pt/Al site occupations could be refined. Magnetic susceptibility measurements showed a disappearance of the complex magnetic ordering phenomena, which are observed in NP-CePtAl.

  13. High pressure mechanical seal

    Science.gov (United States)

    Babel, Henry W. (Inventor); Anderson, Raymond H. (Inventor)

    1996-01-01

    A relatively impervious mechanical seal is formed between the outer surface of a tube and the inside surface of a mechanical fitting of a high pressure fluid or hydraulic system by applying a very thin soft metal layer onto the outer surface of the hard metal tube and/or inner surface of the hard metal fitting. The thickness of such thin metal layer is independent of the size of the tube and/or fittings. Many metals and alloys of those metals exhibit the requisite softness, including silver, gold, tin, platinum, indium, rhodium and cadmium. Suitably, the coating is about 0.0025 millimeters (0.10 mils) in thickness. After compression, the tube and fitting combination exhibits very low leak rates on the order or 10.sup.-8 cubic centimeters per second or less as measured using the Helium leak test.

  14. 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.

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

    Science.gov (United States)

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

    2015-11-01

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

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

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  17. 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

  18. 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

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

    International Nuclear Information System (INIS)

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

    1997-01-01

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

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

    International Nuclear Information System (INIS)

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

    1977-01-01

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

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

    Science.gov (United States)

    Afdal; Wahyuni, E. S.

    2018-03-01

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

  2. 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

  3. 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...

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

    International Nuclear Information System (INIS)

    Mao, Weihua; Atherton, David L.

    2001-01-01

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

  5. 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

  6. Proposed dedicated high pressure beam lines at CHESS

    International Nuclear Information System (INIS)

    Ruoff, A.L.; Vohra, Y.K.; Bassett, W.A.; Batterman, B.W.; Bilderback, D.H.

    1988-01-01

    An instrumentation proposal for dedicated high pressure beam lines at CHESS is described. It is the purpose of this proposed program to provide researchers in high pressure science with beam lines for X-ray diffraction studies in the megabar regime. This will involve radiation from a bending magnet as well as from a wiggler. Examples of the high pressure results up to 2.16 Mbar are shown. Diffraction patterns from bending magnet and wiggler beams are shown and compared. The need for this facility by the high pressure community is discussed. (orig.)

  7. 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

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

    International Nuclear Information System (INIS)

    Hasegawa, Ken

    2010-02-01

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

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

    International Nuclear Information System (INIS)

    Eibler, R.; Neckel, A.

    1975-01-01

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

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

    International Nuclear Information System (INIS)

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

    1985-01-01

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

  11. Magnetic and transport properties of PrRu.sub.2./sub.Si.sub.2./sub. single crystal under high pressure

    Czech Academy of Sciences Publication Activity Database

    Vejpravová, J.; Kamarád, Jiří; Prchal, J.; Sechovsky, V.

    2007-01-01

    Roč. 76, suppl. A (2007), s. 49-50 ISSN 0031-9015 Institutional research plan: CEZ:AV0Z10100521 Keywords : pressure effect * magnetic properties * transport properties * single crystal Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.212, year: 2007

  12. 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.

  13. High pressure research at CHESS

    International Nuclear Information System (INIS)

    Brister, K.

    1992-01-01

    Since February 1990 there has been a dedicated high pressure line at the Cornell High Energy Synchrotron Source (CHESS). This facility provides X-ray instrumentation for energy dispersive X-ray diffraction and Laue diffraction using diamond anvil cells. Both hard-bend magnet and wiggler radiation are available as well as focused monochromatic radiation. In addition, support instrumentation is also available; a ruby system, laser heating, sample loading, and data analysis software. Experienced users need only to bring their diamond anvil cells and samples and can leave with the initial data analysis finished. Research using diamond anvil cells will be introduced and the facility will be described. Some of the diamond anvil cell research done at CHESS will be reviewed, including crystalline to amorphous transitions (R.R. Winters et al., Chem. Phys, in press), properties of C 6 0 under stress (S.J. Duclos et al., Nature 351 (1991) 380), deep earthquakes (T.C. Wu et al., submitted to J. Geophys. Res.)l, and reaching pressures of the center of Earth (A.L. Ruoff et al., Rev. Sci. Instr. 61 (1990) 3830). (orig.)

  14. 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

  15. 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.

  16. 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

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

    International Nuclear Information System (INIS)

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

    1990-01-01

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

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

    International Nuclear Information System (INIS)

    Burnham, A.K.

    1978-01-01

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

  19. Fundamentals of high pressure adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Y.P.; Zhou, L. [Tianjin University, Tianjin (China). High Pressure Adsorption Laboratory

    2009-12-15

    High-pressure adsorption attracts research interests following the world's attention to alternative fuels, and it exerts essential effect on the study of hydrogen/methane storage and the development of novel materials addressing to the storage. However, theoretical puzzles in high-pressure adsorption hindered the progress of application studies. Therefore, the present paper addresses the major theoretical problems that challenged researchers: i.e., how to model the isotherms with maximum observed in high-pressure adsorption; what is the adsorption mechanism at high pressures; how do we determine the quantity of absolute adsorption based on experimental data. Ideology and methods to tackle these problems are elucidated, which lead to new insights into the nature of high-pressure adsorption and progress in application studies, for example, in modeling multicomponent adsorption, hydrogen storage, natural gas storage, and coalbed methane enrichment, was achieved.

  20. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-01-07

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

  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. Collapse of ferromagnetism in itinerant-electron system: A magnetic, transport properties, and high pressure study of (Hf,Ta)Fe2 compounds

    Science.gov (United States)

    Diop, L. V. B.; Kastil, J.; Isnard, O.; Arnold, Z.; Kamarad, J.

    2014-10-01

    The magnetism and transport properties were studied for Laves (Hf,Ta)Fe2 itinerant-electron compounds, which exhibit a temperature-induced first-order transition from the ferromagnetic (FM) to the antiferromagnetic (AFM) state upon heating. At finite temperatures, the field-induced metamagnetic phase transition between the AFM and FM has considerable effects on the transport properties of these model metamagnetic compounds. A large negative magnetoresistance of about 14% is observed in accordance with the metamagnetic transition. The magnetic phase diagram is determined for the Laves Hf1-xTaxFe2 series and its Ta concentration dependence discussed. An unusual behavior is revealed in the paramagnetic state of intermediate compositions, it gives rise to the rapid increase and saturation of the local spin fluctuations of the 3d electrons. This new result is analysed in the frame of the theory of Moriya. For a chosen composition Hf0.825Ta0.175Fe2, exhibiting such remarkable features, a detailed investigation is carried out under hydrostatic pressure up to 1 GPa in order to investigate the volume effect on the magnetic properties. With increasing pressure, the magnetic transition temperature TFM-AFM from ferromagnetic to antiferromagnetic order decreases strongly non-linearly and disappears at a critical pressure of 0.75 GPa. In the pressure-induced AFM state, the field-induced first-order AFM-FM transition appears and the complex temperature dependence of the AFM-FM transition field is explained by the contribution from both the magnetic and elastic energies caused by the significant temperature variation of the amplitude of the local Fe magnetic moment. The application of an external pressure leads also to the progressive decrease of the Néel temperature TN. In addition, a large pressure effect on the spontaneous magnetization MS for pressures below 0.45 GPa, dln(Ms)/dP = -6.3 × 10-2 GPa-1 was discovered. The presented results are consistent with Moriya

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

    Science.gov (United States)

    Hrouda, František; Chadima, Martin; Ježek, Josef

    2018-06-01

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

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

    Science.gov (United States)

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

    2018-04-01

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

  6. 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.

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

    Indian Academy of Sciences (India)

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

  8. 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

  9. High Pressure Industrial Water Facility

    Science.gov (United States)

    1992-01-01

    In conjunction with Space Shuttle Main Engine testing at Stennis, the Nordberg Water Pumps at the High Pressure Industrial Water Facility provide water for cooling the flame deflectors at the test stands during test firings.

  10. High Pressure Research on Materials

    Indian Academy of Sciences (India)

    example, represents the stress on the x plane in the y direction. There are three .... optical studies and studying compressibility of fluids. 3.2 Opposed ..... [4] G N Peggs, High Pressure Measurement Techniques, Applied Science. Publishers ...

  11. High Pressure Physics at Brigham Young University

    Science.gov (United States)

    Decker, Daniel

    2000-09-01

    I will discuss the high pressure research of Drs. J. Dean Barnett, Daniel L. Decker and Howard B. Vanfleet of the department of Physics and Astronomy at Brigham Young University and their many graduate students. I will begin by giving a brief history of the beginning of high pressure research at Brigham Young University when H. Tracy Hall came to the University from General Elecrtric Labs. and then follow the work as it progressed from high pressure x-ray diffraction experiments, melting curve measurements under pressure to pressure effects on tracer diffusion and Mossbauer effect spectra. This will be followed by showing the development of pressure calibration techniques from the Decker equation of state of NaCl to the ruby fluorescence spectroscopy and a short discussion of using a liquid cell for hydrostatic measurements and temperature control for precision high pressure measurements. Then I will conclude with a description of thermoelectric measuremnts, critical phenomena at the magnetic Curie point, and the tricritical point of BaTiO_3.

  12. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1976-03-01

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

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

    Science.gov (United States)

    Wang, Yi; Liu, Tian

    2015-01-01

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

  15. 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

  16. Magnetic susceptibility of one-dimensional ferromagnetic CsFeCl3 crystals

    International Nuclear Information System (INIS)

    Tsuboi, T.; Chiba, M.

    1989-01-01

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

  17. 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.)

  18. Development of a magnetic nanoparticle susceptibility magnitude imaging array

    International Nuclear Information System (INIS)

    Ficko, Bradley W; Nadar, Priyanka M; Hoopes, P Jack; Diamond, Solomon G

    2014-01-01

    There are several emerging diagnostic and therapeutic applications of magnetic nanoparticles (mNPs) in medicine. This study examines the potential for developing an mNP imager that meets these emerging clinical needs with a low cost imaging solution that uses arrays of digitally controlled drive coils in a multiple-frequency, continuous-wave operating mode and compensated fluxgate magnetometers. The design approach is described and a mathematical model is developed to support measurement and imaging. A prototype is used to demonstrate active compensation of up to 185 times the primary applied magnetic field, depth sensitivity up to 2.5 cm (p < 0.01), and linearity over five dilutions (R 2  > 0.98, p < 0.001). System frequency responses show distinguishable readouts for iron oxide mNPs with single magnetic domain core diameters of 10 and 40 nm, and multi-domain mNPs with a hydrodynamic diameter of 100 nm. Tomographic images show a contrast-to-noise ratio of 23 for 0.5 ml of 12.5 mg Fe ml −1  mNPs at 1 cm depth. A demonstration involving the injection of mNPs into pork sausage shows the potential for use in biological systems. These results indicate that the proposed mNP imaging approach can potentially be extended to a larger array system with higher-resolution. (paper)

  19. 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

  20. In line inspection of multi-diameter and high-pressure pipelines in Brazil using combined technologies: magnetic flux leakage and ultrasonic testing

    Energy Technology Data Exchange (ETDEWEB)

    Ginten, Markus; Brockhaus, Stephan; Bouaoua, Nourreddine; Klein, Stefan [ROSEN Technology and Research Center, Lingen (Germany); Bruening, Franz [ROSEN Brazil, Rio de Janeiro, RJ (Brazil)

    2009-07-01

    The simultaneous use of the magnetic flux leakage (MFL) method and the ultrasonic testing (UT) method on a single in line inspection (ILI) tool has been identified as a versatile and accurate solution for liquid pipelines. The combination of the two methods is complementary to the restrictions of each other. Also, the overall scope of the inspection is enlarged. General wall thinning and largely corroded areas are accurately and reliably scanned with the UT unit, while very detailed information about pitting corrosion is obtained from the MFL measurement. Blind spots of echo loss, as occasionally observed for the UT channels is compensated by the more robust measurement from the MFL sensors. Consequently, this technology has been the method of choice in an in line inspection project of an onshore long distance pipeline in Brazil, facing a variety of corrosion threats. The pipeline consists of several multi-diameter sections of 18/20 inches and 20/22 inches. Furthermore, the high gravity of product in combination with a height profile, an altitude of 1152 m MSL (Mean Sea Level) had to be crossed, leads to a maximum pressure of 220 bar. These boundary conditions had to be considered during the design of the ILI-tool. The paper discusses the experience made so far with the combined technology MFL and UT. The effective use of the inspection tool for the above mentioned pipeline as well as field results from a previous inspection are described. (author)

  1. The appearance of homogeneous antiferromagnetism in URu sub 2 Si sub 2 under high pressure: a sup 2 sup 9 Si nuclear magnetic resonance study

    CERN Document Server

    Matsuda, K; Kohara, T; Amitsuka, H; Kuwahara, K; Matsumoto, T

    2003-01-01

    We have investigated the low-temperature phase appearing below T sub o = 17.5 K in URu sub 2 Si sub 2 by means of sup 2 sup 9 Si nuclear magnetic resonance (NMR) in a pressure range from 0 to 17.5 kbar across the pressure-induced phase transition at P sub c = 15 kbar. At pressures below P sub c , we have observed the sup 2 sup 9 Si NMR lines arising from antiferromagnetic (AF) and paramagnetic (PM) regions in the sample, giving evidence for a phase-separated AF ordering below T sub o. The AF region increases in volume fraction with increasing pressure up to P sub c. In the PM region, the temperature-dependence of the nuclear spin-lattice relaxation rate at Si sites shows a rapid decrease below T sub o , strongly suggesting the occurrence of a phase transition driven by a hidden order parameter. As applied pressure exceeds P sub c , the AF ordering appears uniformly at T sub o throughout the sample. In the pressure range from 0 to 17.5 kbar, the magnitude of the internal field at Si sites in the AF region rema...

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

    Science.gov (United States)

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

    2018-05-01

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

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

    Directory of Open Access Journals (Sweden)

    M. E. Gettings

    2005-01-01

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

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

    Science.gov (United States)

    Gettings, M.E.

    2005-01-01

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

  5. High-pressure synthesis and magnetic behavior of A-site columnar-ordered double perovskites, LnMn(Ga{sub 0.5}Ti{sub 0.5}){sub 2}O{sub 6} (Ln = Sm, Gd)

    Energy Technology Data Exchange (ETDEWEB)

    Shimura, Gen; Niwa, Ken; Shirako, Yuichi; Hasegawa, Masashi [Department of Crystalline Materials Science, Nagoya University, 464-8601, Nagoya (Japan)

    2017-01-26

    A-site columnar-ordered double perovskites, LnMn(Ga{sub 0.5}Ti{sub 0.5}){sub 2}O{sub 6} (Ln = Sm, Gd), were successfully synthesized under high pressure and high temperature (6 GPa, 1375 K). From the synchrotron powder X-ray diffraction patterns, all of the diffraction peaks can be indexed by the P4{sub 2}/nmc space group with lattice parameters a, c ∼ 2a{sub p} (a{sub p}: primitive cubic perovskite lattice) and no ordering of the B-site cations. Rietveld analysis of the synchrotron powder X-ray diffraction patterns and Curie-Weiss fitting of their magnetizations reveal that the ionic formulae of these perovskites are Ln{sup 3+}Mn{sup 2+}(Ga{sup 3+}{sub 0.5}Ti{sup 4+}{sub 0.5}){sub 2}O{sup 2-}{sub 6}. SmMn(Ga{sub 0.5}Ti{sub 0.5}){sub 2}O{sub 6} shows canted-antiferromagnetic behavior, whereas GdMn(Ga{sub 0.5}Ti{sub 0.5}){sub 2}O{sub 6} exhibits two different magnetic states at low temperature depending on the applied magnetic field and shows an unusual magnetization curve. These magnetic behaviors originate by decreasing the antiferromagnetic interaction by substituting Ga{sup 3+}(d{sup 10}) for Ti{sup 4+}(d{sup 0}) and by decreasing the ferromagnetic interaction between columnar-ordered Ln{sup 3+} and Mn{sup 2+}. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. 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.

  7. 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.

  8. 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

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

    Digital Repository Service at National Institute of Oceanography (India)

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

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

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

    International Nuclear Information System (INIS)

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

    1994-01-01

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

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

    International Nuclear Information System (INIS)

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

    1976-01-01

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

  12. High pressure effects on the crystal and magnetic structure ofnanostructured manganites La.sub.0.63./sub.Sr.sub.0.37./sub.MnO.sub.3./sub. and La.sub.0.72./sub.Sr.sub.0.28./sub.MnO.sub.3./sub..

    Czech Academy of Sciences Publication Activity Database

    Belozerova, N.M.; Kichanov, S.E.; Jirák, Zdeněk; Kozlenko, D. P.; Kačenka, Michal; Kaman, Ondřej; Lukin, E.V.; Savenko, B. N.

    2015-01-01

    Roč. 646, Oct (2015), s. 998-1003 ISSN 0925-8388 R&D Projects: GA ČR GA15-10088S Institutional support: RVO:68378271 Keywords : manganites * nanoparticles * neutron diffraction * high pressure * magnetic phase separation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.014, year: 2015

  13. High-pressure sodium lamp

    NARCIS (Netherlands)

    1996-01-01

    A high pressure sodium lamp of the invention is provided with a discharge vessel (20) which is enclosed with intervening space (1) by an outer bulb (10), which space contains a gas-fill with at least 70 mol. % nitrogen gas. Electrodes (30a, 30b) are positioned in the discharge vessel (20) and are

  14. Intermolecular Interactions at high pressure

    DEFF Research Database (Denmark)

    Eikeland, Espen Zink

    2016-01-01

    In this project high-pressure single crystal X-ray diffraction has been combined with quantitative energy calculations to probe the energy landscape of three hydroquinone clathrates enclosing different guest molecules. The simplicity of the hydroquinone clathrate structures together with their st...

  15. High-pressure water facility

    Science.gov (United States)

    2006-01-01

    NASA Test Operations Group employees, from left, Todd Pearson, Tim Delcuze and Rodney Wilkinson maintain a water pump in Stennis Space Center's high-pressure water facility. The three were part of a group of employees who rode out Hurricane Katrina at the facility and helped protect NASA's rocket engine test complex.

  16. High pressure phase transformations revisited.

    Science.gov (United States)

    Levitas, Valery I

    2018-04-25

    High pressure phase transformations play an important role in the search for new materials and material synthesis, as well as in geophysics. However, they are poorly characterized, and phase transformation pressure and pressure hysteresis vary drastically in experiments of different researchers, with different pressure transmitting media, and with different material suppliers. Here we review the current state, challenges in studying phase transformations under high pressure, and the possible ways in overcoming the challenges. This field is critically compared with fields of phase transformations under normal pressure in steels and shape memory alloys, as well as plastic deformation of materials. The main reason for the above mentioned discrepancy is the lack of understanding that there is a fundamental difference between pressure-induced transformations under hydrostatic conditions, stress-induced transformations under nonhydrostatic conditions below yield, and strain-induced transformations during plastic flow. Each of these types of transformations has different mechanisms and requires a completely different thermodynamic and kinetic description and experimental characterization. In comparison with other fields the following challenges are indicated for high pressure phase transformation: (a) initial and evolving microstructure is not included in characterization of transformations; (b) continuum theory is poorly developed; (c) heterogeneous stress and strain fields in experiments are not determined, which leads to confusing material transformational properties with a system behavior. Some ways to advance the field of high pressure phase transformations are suggested. The key points are: (a) to take into account plastic deformations and microstructure evolution during transformations; (b) to formulate phase transformation criteria and kinetic equations in terms of stress and plastic strain tensors (instead of pressure alone); (c) to develop multiscale continuum

  17. High pressure phase transformations revisited

    Science.gov (United States)

    Levitas, Valery I.

    2018-04-01

    High pressure phase transformations play an important role in the search for new materials and material synthesis, as well as in geophysics. However, they are poorly characterized, and phase transformation pressure and pressure hysteresis vary drastically in experiments of different researchers, with different pressure transmitting media, and with different material suppliers. Here we review the current state, challenges in studying phase transformations under high pressure, and the possible ways in overcoming the challenges. This field is critically compared with fields of phase transformations under normal pressure in steels and shape memory alloys, as well as plastic deformation of materials. The main reason for the above mentioned discrepancy is the lack of understanding that there is a fundamental difference between pressure-induced transformations under hydrostatic conditions, stress-induced transformations under nonhydrostatic conditions below yield, and strain-induced transformations during plastic flow. Each of these types of transformations has different mechanisms and requires a completely different thermodynamic and kinetic description and experimental characterization. In comparison with other fields the following challenges are indicated for high pressure phase transformation: (a) initial and evolving microstructure is not included in characterization of transformations; (b) continuum theory is poorly developed; (c) heterogeneous stress and strain fields in experiments are not determined, which leads to confusing material transformational properties with a system behavior. Some ways to advance the field of high pressure phase transformations are suggested. The key points are: (a) to take into account plastic deformations and microstructure evolution during transformations; (b) to formulate phase transformation criteria and kinetic equations in terms of stress and plastic strain tensors (instead of pressure alone); (c) to develop multiscale continuum

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

    Science.gov (United States)

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

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

  19. High-pressure synthesis, crystal structure, and magnetic properties of KSbO3-type 5d oxides K0.84OsO3 and Bi2.93Os3O11

    Science.gov (United States)

    Yuan, Yahua; Feng, Hai L.; Shi, Youguo; Tsujimoto, Yoshihiro; Belik, Alexei A.; Matsushita, Yoshitaka; Arai, Masao; He, Jianfeng; Tanaka, Masahiko; Yamaura, Kazunari

    2014-12-01

    5d Solid-state oxides K0.84OsO3 (Os5.16+; 5d 2.84) and Bi2.93Os3O11 (Os4.40+; 5d 3.60) were synthesized under high-pressure and high-temperature conditions (6 GPa and 1500-1700 °C). Their crystal structures were determined by synchrotron x-ray diffraction and their 5d electronic properties and tunnel-like structure motifs were investigated. A KSbO3-type structure with a space group of Im-3 and Pn-3 was determined for K0.84OsO3 and Bi2.93Os3O11, respectively. The magnetic and electronic transport properties of the polycrystalline compounds were compared with those obtained theoretically. It was revealed that the 5d tunnel-like structures are paramagnetic with metallic charge conduction at temperatures above 2 K. This was similar to what was observed for structurally relevant 5d oxides, including Bi3Re3O11 (Re4.33+; 5d 2.66) and Ba2Ir3O9 (Ir4.66+; 5d 4.33). The absence of long-range magnetic order seems to be common among 5d KSbO3-like oxides, regardless of the number of 5d electrons (between 2.6 and 4.3 per 5d atom).

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

    Science.gov (United States)

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

    2018-02-01

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

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

    International Nuclear Information System (INIS)

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

    1982-01-01

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

  2. 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.

  3. 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.

  4. Computer simulation at high pressure

    International Nuclear Information System (INIS)

    Alder, B.J.

    1977-11-01

    The use of either the Monte Carlo or molecular dynamics method to generate equations-of-state data for various materials at high pressure is discussed. Particular emphasis is given to phase diagrams, such as the generation of various types of critical lines for mixtures, melting, structural and electronic transitions in solids, two-phase ionic fluid systems of astrophysical interest, as well as a brief aside of possible eutectic behavior in the interior of the earth. Then the application of the molecular dynamics method to predict transport coefficients and the neutron scattering function is discussed with a view as to what special features high pressure brings out. Lastly, an analysis by these computational methods of the measured intensity and frequency spectrum of depolarized light and also of the deviation of the dielectric measurements from the constancy of the Clausius--Mosotti function is given that leads to predictions of how the electronic structure of an atom distorts with pressure

  5. Terbium oxide at high pressures

    International Nuclear Information System (INIS)

    Dogra, Sugandha; Sharma, Nita Dilawar; Singh, Jasveer; Bandhyopadhyay, A.K.

    2011-01-01

    In this work we report the behaviour of terbium oxide at high pressures. The as received sample was characterized at ambient by X-ray diffraction and Raman spectroscopy. The X-ray diffraction showed the sample to be predominantly cubic Tb 4 O 7 , although a few peaks also match closely with Tb 2 O 3 . In fact in a recent study done on the same sample, the sample has been shown to be a mixture of Tb 4 O 7 and Tb 2 O 3 . The sample was subjected to high pressures using a Mao-Bell type diamond anvil cell upto a pressure of about 42 GPa with ruby as pressure monitor

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

    Science.gov (United States)

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

    2018-06-01

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

  7. Cryogenic, Absolute, High Pressure Sensor

    Science.gov (United States)

    Chapman, John J. (Inventor); Shams. Qamar A. (Inventor); Powers, William T. (Inventor)

    2001-01-01

    A pressure sensor is provided for cryogenic, high pressure applications. A highly doped silicon piezoresistive pressure sensor is bonded to a silicon substrate in an absolute pressure sensing configuration. The absolute pressure sensor is bonded to an aluminum nitride substrate. Aluminum nitride has appropriate coefficient of thermal expansion for use with highly doped silicon at cryogenic temperatures. A group of sensors, either two sensors on two substrates or four sensors on a single substrate are packaged in a pressure vessel.

  8. Cryogenic High Pressure Sensor Module

    Science.gov (United States)

    Chapman, John J. (Inventor); Shams, Qamar A. (Inventor); Powers, William T. (Inventor)

    1999-01-01

    A pressure sensor is provided for cryogenic, high pressure applications. A highly doped silicon piezoresistive pressure sensor is bonded to a silicon substrate in an absolute pressure sensing configuration. The absolute pressure sensor is bonded to an aluminum nitride substrate. Aluminum nitride has appropriate coefficient of thermal expansion for use with highly doped silicon at cryogenic temperatures. A group of sensors, either two sensors on two substrates or four sensors on a single substrate are packaged in a pressure vessel.

  9. Brillouin scattering at high pressures

    International Nuclear Information System (INIS)

    Grimsditch, M.; Polian, A.

    1988-02-01

    Technical advances which have made Brillouin scattering a useful tool in high pressure diamond anvil cell (DAC) studies, viz. multipassing and tandem operation of Fabry-Perot interferometers, are reviewed. Experimental aspects, such as allowed scattering geometries, are outlined and the data analysis required to transform Brillouin spectra into sound velocities and elastic constants is presented. Experimental results on H 2 , N 2 , Ar, and He are presented, and the close relationship between the Brillouin scattering results and equations of state is highlighted

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

    Science.gov (United States)

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

    2016-10-01

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

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

    Science.gov (United States)

    Yang, Pingguo; Ge, Jing; Yang, Miao

    2017-06-01

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

  12. Model of Structural Fragmentation Induced by High Pressure Torsion

    Czech Academy of Sciences Publication Activity Database

    Kratochvíl, J.; Kružík, Martin; Sedláček, R.

    2010-01-01

    Roč. 25, č. 1 (2010), s. 88-98 ISSN 1606-5131 Institutional research plan: CEZ:AV0Z10750506 Keywords : High-pressure torsion * intergranular glide * homogeneous deformation mode Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.649, year: 2010 http://library.utia.cas.cz/separaty/2010/MTR/kruzik-model of structural fragmentation induced by high pressure torsion.pdf

  13. 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).

  14. Magnetic susceptibility of sodium disilicate glasses containing PuO2

    International Nuclear Information System (INIS)

    Aldred, A.T.

    1979-01-01

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

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

    International Nuclear Information System (INIS)

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

    1999-01-01

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

  16. 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.

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

    Science.gov (United States)

    Boda, Aalu; Chatterjee, Ashok

    2018-04-01

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

  18. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-03-01

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

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

    International Nuclear Information System (INIS)

    Fujiwara, Y; Tanimoto, Y

    2009-01-01

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

  1. 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

  2. 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

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

    OpenAIRE

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

    2014-01-01

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

  4. 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

  5. High pressure experimental water loop

    International Nuclear Information System (INIS)

    Grenon, M.

    1958-01-01

    A high pressure experimental water loop has been made for studying the detection and evolution of cladding failure in a pressurized reactor. The loop has been designed for a maximum temperature of 360 deg. C, a maximum of 160 kg/cm 2 and flow rates up to 5 m 3 /h. The entire loop consists of several parts: a main circuit with a canned rotor circulation pump, steam pressurizer, heating tubes, two hydro-cyclones (one de-gasser and one decanter) and one tubular heat exchanger; a continuous purification loop, connected in parallel, comprising pressure reducing valves and resin pots which also allow studies of the stability of resins under pressure, temperature and radiation; following the gas separator is a gas loop for studying the recombination of the radiolytic gases in the steam phase. The preceding circuits, as well as others, return to a low pressure storage circuit. The cold water of the low pressure storage flask is continuously reintroduced into the high pressure main circuit by means of a return pump at a maximum head of 160 kg /cm 2 , and adjusted to the pressurizer level. This loop is also a testing bench for the tight high pressure apparatus. The circulating pump and the connecting flanges (Oak Ridge type) are water-tight. The feed pump and the pressure reducing valves are not; the un-tight ones have a system of leak recovery. To permanently check the tightness the circuit has been fitted with a leak detection system (similar to the HRT one). (author) [fr

  6. 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.

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

    NARCIS (Netherlands)

    Dekkers, M.J.

    1988-01-01

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

  8. 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.

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

    Science.gov (United States)

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

    2017-12-01

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

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  11. 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

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

    Directory of Open Access Journals (Sweden)

    Shimakura Hironori

    2017-01-01

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

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

    International Nuclear Information System (INIS)

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

    1980-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Jatto S. Solomon

    2017-07-01

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

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

    Science.gov (United States)

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

    1991-01-01

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

  16. High pressure Moessbauer spectroscopy of perovskite iron oxide

    CERN Document Server

    Nasu, S; Morimoto, S; Kawakami, T; Kuzushita, K; Takano, M

    2003-01-01

    High-pressure sup 5 sup 7 Fe Moessbauer spectroscopy using a diamond anvil cell has been performed for perovskite iron oxides SrFeO sub 3 , CaFeO sub 3 and La sub 1 sub / sub 3 Sr sub 2 sub / sub 3 O sub 3. The charge states and the magnetic dependency to pressure were determined. Pressure magnetic phase diagrams of these perovskite iron oxides are determined up to about 70 GPa. To be clear the magnetic ordered state, they are measured up to 7.8 T external magnetic fields at 4.5K. The phase transition of these perovskite oxides to ferromagnetisms with high magnetic ordered temperature is observed. In higher pressure, high spin-low spin transition of oxides besides CaFeO sub 3 is generated. The feature of Moessbauer spectroscopy, perovskite iron oxide and Moessbauer spectroscopy under high pressure are explained. (S.Y.)

  17. High pressure Moessbauer spectroscopy of perovskite iron oxide

    International Nuclear Information System (INIS)

    Nasu, Saburo; Suenaga, Tomoya; Morimoto, Shotaro; Kawakami, Takateru; Kuzushita, Kaori; Takano, Mikio

    2003-01-01

    High-pressure 57 Fe Moessbauer spectroscopy using a diamond anvil cell has been performed for perovskite iron oxides SrFeO 3 , CaFeO 3 and La 1/3 Sr 2/3 O 3 . The charge states and the magnetic dependency to pressure were determined. Pressure magnetic phase diagrams of these perovskite iron oxides are determined up to about 70 GPa. To be clear the magnetic ordered state, they are measured up to 7.8 T external magnetic fields at 4.5K. The phase transition of these perovskite oxides to ferromagnetisms with high magnetic ordered temperature is observed. In higher pressure, high spin-low spin transition of oxides besides CaFeO 3 is generated. The feature of Moessbauer spectroscopy, perovskite iron oxide and Moessbauer spectroscopy under high pressure are explained. (S.Y.)

  18. Solids, liquids, and gases under high pressure

    Science.gov (United States)

    Mao, Ho-Kwang; Chen, Xiao-Jia; Ding, Yang; Li, Bing; Wang, Lin

    2018-01-01

    Pressure has long been recognized as a fundamental thermodynamic variable but its application was previously limited by the available pressure vessels and probes. The development of megabar diamond anvil cells and a battery of associated in-laboratory and synchrotron techniques at the turn of the century have opened a vast new window of opportunities. With the addition of the pressure dimension, we are facing a new world with an order of magnitude more materials to be discovered than all that have been explored at ambient pressure. Pressure drastically and categorically alters all elastic, electronic, magnetic, structural, and chemical properties, and pushes materials across conventional barriers between insulators and superconductors, amorphous and crystalline solids, ionic and covalent compounds, vigorously reactive and inert chemicals, etc. In the process, it reveals surprising high-pressure physics and chemistry and creates novel materials. This review describes the principles and methodology used to reach ultrahigh static pressure: the in situ probes, the physical phenomena to be investigated, the long-pursued goals, the surprising discoveries, and the vast potential opportunities. Exciting examples include the quest for metallic hydrogen, the record-breaking superconducting temperature of 203 K in HnS , the complication of "free-electron gas" alkali metals, the magnetic collapse in 3 d transition elements, the pressure-induced superconductivity from topological insulators, the novel stoichiometry in simple compounds, the interaction of nanoscience, the accomplishment of 750 GPa pressure, etc. These highlights are the integral results of technological achievements, specific measurements, and theoretical advancement; therefore, the same highlights will appear in different sections corresponding to these different aspects. Overall, this review demonstrates that high-pressure research is a new dimension in condensed-matter physics.

  19. Magnetic susceptibility of LaxCe1-xF3 single crystals

    International Nuclear Information System (INIS)

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

    2000-01-01

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

  20. 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.

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

    Science.gov (United States)

    Samardzic, Dejan; Thamburaj, Krishnamoorthy

    2015-01-01

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

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

    International Nuclear Information System (INIS)

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

    2008-01-01

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

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

    Science.gov (United States)

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

    2016-01-01

    In the present study, novel MRI compatible zirconium-ruthenium alloys with ultralow magnetic susceptibility were developed for biomedical and therapeutic devices under MRI diagnostics environments. The results demonstrated that alloying with ruthenium into pure zirconium would significantly increase the strength and hardness properties. The corrosion resistance of zirconium-ruthenium alloys increased significantly. High cell viability could be found and healthy cell morphology observed when culturing MG 63 osteoblast-like cells and L-929 fibroblast cells with zirconium-ruthenium alloys, whereas the hemolysis rates of zirconium-ruthenium alloys are alloys and Ti-based alloys, the magnetic susceptibilities of the zirconium-ruthenium alloys (1.25 × 10−6 cm3·g−1–1.29 × 10−6 cm3·g−1 for zirconium-ruthenium alloys) are ultralow, about one-third that of Ti-based alloys (Ti–6Al–4V, ~3.5 × 10−6 cm3·g−1, CP Ti and Ti–6Al–7Nb, ~3.0 × 10−6 cm3·g−1), and one-sixth that of Co–Cr alloys (Co–Cr–Mo, ~7.7 × 10−6 cm3·g−1). Among the Zr–Ru alloy series, Zr–1Ru demonstrates enhanced mechanical properties, excellent corrosion resistance and cell viability with lowest magnetic susceptibility, and thus is the optimal Zr–Ru alloy system as therapeutic devices under MRI diagnostics environments. PMID:27090955

  4. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-08-20

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

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

    Science.gov (United States)

    Zalom, Peter; Pokorný, Vladislav; Janiš, Václav

    2018-05-01

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

  7. High Pressure Electrolyzer System Evaluation

    Science.gov (United States)

    Prokopius, Kevin; Coloza, Anthony

    2010-01-01

    This report documents the continuing efforts to evaluate the operational state of a high pressure PEM based electrolyzer located at the NASA Glenn Research Center. This electrolyzer is a prototype system built by General Electric and refurbished by Hamilton Standard (now named Hamilton Sunstrand). It is capable of producing hydrogen and oxygen at an output pressure of 3000 psi. The electrolyzer has been in storage for a number of years. Evaluation and testing was performed to determine the state of the electrolyzer and provide an estimate of the cost for refurbishment. Pressure testing was performed using nitrogen gas through the oxygen ports to ascertain the status of the internal membranes and seals. It was determined that the integrity of the electrolyzer stack was good as there were no appreciable leaks in the membranes or seals within the stack. In addition to the integrity testing, an itemized list and part cost estimate was produced for the components of the electrolyzer system. An evaluation of the system s present state and an estimate of the cost to bring it back to operational status was also produced.

  8. High pressure processing's potential to inactivate norovirus and other fooodborne viruses

    Science.gov (United States)

    High pressure processing (HPP) can inactivate human norovirus. However, all viruses are not equally susceptible to HPP. Pressure treatment parameters such as required pressure levels, initial pressurization temperatures, and pressurization times substantially affect inactivation. How food matrix ...

  9. High pressure apparatus for neutron scattering at low temperature

    International Nuclear Information System (INIS)

    Munakata, Koji; Uwatoko, Yoshiya; Aso, Naofumi

    2010-01-01

    Effects of pressure on the physical properties are very important for understanding highly correlated electron systems, in which pressure-induced attractive phenomena such as superconductivity and magnetically ordered non-Fermi liquid have been observed. Up to now, many scientists have developed a lot of high pressure apparatus for each purpose. The characteristic features of various materials and pressure transmitting media for use of high pressure apparatus are reported. Then, two kinds of clamp type high-pressure cell designed for low-temperature neutron diffraction measurements are shown; one is a piston cylinder type high-pressure cell which can be attached to the dilution refrigerator, and the other one is a newly-developed cubic anvil type high-pressure cell which can generate pressure above 7GPa. We also introduce the results of magnetic neutron scattering under pressure on a pressure-induced superconducting ferromagnet UGe 2 in use of the piston cylinder type clamp cell, and those on an iron arsenide superconductor SrFe 2 As 2 in use of the cubic anvil type clamp cell. (author)

  10. Phase transitions in solids under high pressure

    CERN Document Server

    Blank, Vladimir Davydovich

    2013-01-01

    Phase equilibria and kinetics of phase transformations under high pressureEquipment and methods for the study of phase transformations in solids at high pressuresPhase transformations of carbon and boron nitride at high pressure and deformation under pressurePhase transitions in Si and Ge at high pressure and deformation under pressurePolymorphic α-ω transformation in titanium, zirconium and zirconium-titanium alloys Phase transformations in iron and its alloys at high pressure Phase transformations in gallium and ceriumOn the possible polymorphic transformations in transition metals under pressurePressure-induced polymorphic transformations in АIBVII compoundsPhase transformations in AIIBVI and AIIIBV semiconductor compoundsEffect of pressure on the kinetics of phase transformations in iron alloysTransformations during deformation at high pressure Effects due to phase transformations at high pressureKinetics and hysteresis in high-temperature polymorphic transformations under pressureHysteresis and kineti...

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

    Science.gov (United States)

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

    2012-12-01

    station) in the western side of King George Island. The plutonic rocks of diorite and granodiorite show high values of bulk magnetic susceptibility of c.a. 0.01-0.4 SI, appearing to be the source of positive magnetic anomaly. We also revealed the preferred petrofabric lineation directions at the sites using anisotropy of magnetic susceptibility (AMS). The AMS showed the plutonic rocks represent the vertical intrusion from the deep seated magma. Our optical microscope observation verified the maximum AMS orientation is parallel to the preferred alignment of framework-forming plagioclase, suggesting the alignment of euhedral magnetite grains along the long-axes of plagioclases. Our ship-borne and foot-borne surveys of geomagnetic filed anomaly agree well with the distribution of the plutonic rocks, revealing the possible origin of surface magnetic anomaly. These suggests that the plutons in this area may be included ACG, and this magnetic surveys is proposed to infer the availability to find out the presence of granitoid.

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

    International Nuclear Information System (INIS)

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

    1988-01-01

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

  13. 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

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

    Science.gov (United States)

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

    2016-04-15

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

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

    Science.gov (United States)

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

    2017-11-01

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

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

    Science.gov (United States)

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

    2016-12-01

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

  17. Study of magnetic, structural and magnetocaloric properties of La{sub 0.6}Pr{sub 0.4}Mn{sub 2}Si{sub 2} under high pressures and magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Kaštil, J., E-mail: kastil@fzu.cz [Institute of Physics AS CR v.v.i., Na Slovance 2, 182 21 Prague 8 (Czech Republic); Arnold, Z. [Institute of Physics AS CR v.v.i., Na Slovance 2, 182 21 Prague 8 (Czech Republic); Isnard, O. [Centre national de la recherche scientifique (CNRS), Institut Néel, 25 rus des martyrs, F-38042 Grenoble (France); Université Grenoble Alpes, Institut Néel, F-38042 Grenoble (France); Skourski, Y. [Hochfeld-Magnetlabor Dresden (HLD), HZ Dresden-Rossendorf, D-01314 Dresden (Germany); Kamarád, J. [Institute of Physics AS CR v.v.i., Na Slovance 2, 182 21 Prague 8 (Czech Republic); Itié, J.P. [Synchrotron SOLEIL, L' Orme des Merisiers, Saint-Aubin, 91192 Gif-sur-Yvette (France)

    2017-02-15

    The structural, magnetic and magnetocaloric properties of La{sub 0.6}Pr{sub 0.4}Mn{sub 2}Si{sub 2} compound were measured in wide range of temperature, magnetic field and hydrostatic pressure. The structural study up to 10 GPa confirmed the existence of critical Mn-Mn distance 0.2883 nm for the ferromagnetic to antiferromagnetic transition at room temperature. The results demonstrated the crucial role of the volume in the suppression of the ferromagnetic phase above the transition temperature T{sub 1}=168 K under pressure. The huge pressure shift of the transition temperature T{sub 1}, dT{sub 1}/dp=230 K/GPa, was observed. Based on our magnetization measurement the low temperature transition at T{sub 2}=30 K is connected with reorientation of Mn moment and the rare-earth sublattice is not ordered in this case. The direct magnetocaloric measurement showed moderate values of the adiabatic temperature change connected with the magnetic transition at T{sub c} and T{sub 1} and confirmed the first order character of the transition at T{sub 1} and second order character of the transition at T{sub c}. - Highlights: • The huge pressure shift of the transition temperature dT{sub 1}/dp=230 K/GPa was observed. • Ferromagnetic order is suppressed by applying pressure of 1 GPa. • The direct magnetocaloric effect showed moderate values of ΔT{sub ad}.

  18. 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.

  19. 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.

  20. 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.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2017-08-09

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

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

    International Nuclear Information System (INIS)

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

    2005-01-01

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

  4. 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.

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

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  6. On the origin of the giant isotopic effect of hydrogen on the magnetic properties of YFe.sub.2./sub.A.sub.4.2./sub. (A = H, D): a high pressure study

    Czech Academy of Sciences Publication Activity Database

    Isnard, O.; Paul-Boncour, V.; Arnold, Zdeněk

    2013-01-01

    Roč. 102, č. 12 (2013), "122408-1"-"122408-4" ISSN 0003-6951 R&D Projects: GA ČR GAP204/12/0692 Institutional support: RVO:68378271 Keywords : antiferromagnetic materials * compressibility * ferromagnetic materials * ferromagnetic-antiferromagnetic transitions * high- pressure effects * iron compoounds Subject RIV: BE - Theoretical Physics Impact factor: 3.515, year: 2013

  7. Emplacement, petrological and magnetic susceptibility characteristics of diverse magmatic epidote-bearing granitoid rocks in Brazil, Argentina and Chile

    Science.gov (United States)

    Sial, A. N.; Toselli, A. J.; Saavedra, J.; Parada, M. A.; Ferreira, V. P.

    1999-03-01

    Magmatic epidote (mEp)-bearing granitoids from five Neoproterozoic tectonostratigraphic terranes in Northeastern (NE) Brazil, Early Palaeozoic calc-alkalic granitoids in Northwestern (NW) Argentina and from three batholiths in Chile have been studied. The elongated shape of some of these plutons suggests that magmas filled fractures and that dyking was probably the major mechanism of emplacement. Textures reveal that, in many cases, epidote underwent partial dissolution by host magma and, in these cases, may have survived dissolution by relatively rapid upward transport by the host magma. In plutons where such a mechanism is not evident, unevenly distributed epidote at outcrop scale is armoured by biotite or near-solidus K-feldspar aggregates, which probably grew much faster than epidote dissolution, preventing complete resorption of epidote by the melt. Al-in-hornblende barometry indicates that, in most cases, amphibole crystallized at P≥5 kbar. Kyanite-bearing thermal aureoles surrounding plutons that intruded low-grade metamorphic rocks in NE Brazil support pluton emplacement at intermediate to high pressure. mEp show overall chemical variation from 20 to 30 mol% (mole percent) pistacite (Ps) and can be grouped into two compositional ranges: Ps 20-24 and Ps 27-30. The highest Ps contents are in epidotes of plutons in which hornblende solidified under Pcorrosion of individual epidote crystals included in plagioclase in high-K calc-alkalic granitoids in NE Brazil, emplaced at 5-7 kbar pressure, yielded estimates of magma transport rate from 70 to 350 m year -1. Most of these plutons lack Fe-Ti oxide minerals and Fe +3 is mostly associated with the epidote structure. Consequently, magnetic susceptibility (MS) in the Neoproterozoic granitoids in NE Brazil, as well as Early Palaeozoic plutons in Argentina and Late Palaeozoic plutons in Chile, is usually low (3.0×10 -3 SI, typical of magnetite-series granitoids crystallized under higher oxygen fugacity. In NE

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

    Science.gov (United States)

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

    2018-05-01

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

  9. High-Pressure Lightweight Thrusters

    Science.gov (United States)

    Holmes, Richard; McKechnie, Timothy; Shchetkovskiy, Anatoliy; Smirnov, Alexander

    2013-01-01

    Returning samples of Martian soil and rock to Earth is of great interest to scientists. There were numerous studies to evaluate Mars Sample Return (MSR) mission architectures, technology needs, development plans, and requirements. The largest propulsion risk element of the MSR mission is the Mars Ascent Vehicle (MAV). Along with the baseline solid-propellant vehicle, liquid propellants have been considered. Similar requirements apply to other lander ascent engines and reaction control systems. The performance of current state-ofthe- art liquid propellant engines can be significantly improved by increasing both combustion temperature and pressure. Pump-fed propulsion is suggested for a single-stage bipropellant MAV. Achieving a 90-percent stage propellant fraction is thought to be possible on a 100-kg scale, including sufficient thrust for lifting off Mars. To increase the performance of storable bipropellant rocket engines, a high-pressure, lightweight combustion chamber was designed. Iridium liner electrodeposition was investigated on complex-shaped thrust chamber mandrels. Dense, uniform iridium liners were produced on chamber and cylindrical mandrels. Carbon/carbon composite (C/C) structures were braided over iridium-lined mandrels and densified by chemical vapor infiltration. Niobium deposition was evaluated for forming a metallic attachment flange on the carbon/ carbon structure. The new thrust chamber was designed to exceed state-of-the-art performance, and was manufactured with an 83-percent weight savings. High-performance C/Cs possess a unique set of properties that make them desirable materials for high-temperature structures used in rocket propulsion components, hypersonic vehicles, and aircraft brakes. In particular, more attention is focused on 3D braided C/Cs due to their mesh-work structure. Research on the properties of C/Cs has shown that the strength of composites is strongly affected by the fiber-matrix interfacial bonding, and that weakening

  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. 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.

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

    International Nuclear Information System (INIS)

    Stierman, R.J.

    1982-12-01

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

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

    International Nuclear Information System (INIS)

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

    1974-01-01

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

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

    International Nuclear Information System (INIS)

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

    1997-01-01

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

  15. 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.

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

    Science.gov (United States)

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

    2016-04-19

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

  17. High pressure effects on fruits and vegetables

    NARCIS (Netherlands)

    Timmermans, R.A.H.; Matser, A.M.

    2016-01-01

    The chapter provides an overview on different high pressure based treatments (high pressure pasteurization, blanching, pressure-assisted thermal processing, pressure-shift freezing and thawing) available for the preservation of fruits and vegetable products and extending their shelf life. Pressure

  18. 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.

  19. 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)

  20. Structural and electrical properties of TmTe under high pressure

    International Nuclear Information System (INIS)

    Tang, Jie; Matsumoto, Takehiko; Kosaka, Takayuki; Matsumura, Takeshi; Suzuki, Takashi; Mori, Nobuo

    1997-01-01

    Pressure-induced valence state of Tm ions in TmTe has been investigated by measurements of electrical resistivity in situ x-ray diffraction and magnetic susceptibility at high pressure. Below 2 GPa, the valence of Tm was confirmed to be 2 + from the results of compressibility and magnetic susceptibility. The pressure dependence of the electrical resistivity up to 2 GPa at room temperature showed an exponential decrease, indicating a linear closing of the energy gap at a rate of -1 meV/GPa. In the pressure range above 2 GPa where the energy gap disappeared, the valence transition from Tm 2+ to Tm 3+ was concluded from the pressure dependence of the lattice parameters. The electrical resistivity showing a logarithmic temperature dependence was reminiscent of Kondo effect. Above 6 GPa at which the pressure dependence of electrical resistivity abruptly decreased, the structure was confirmed to transform from the NaCl-type with Tm 3+ to a tetragonal structure. (author)

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

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

    International Nuclear Information System (INIS)

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

    2000-01-01

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

  3. Design and testing of high-pressure railguns and projectiles

    International Nuclear Information System (INIS)

    Peterson, D.R.; Fowler, C.M.

    1984-01-01

    The results of high-pressure tests of four railgun designs and four projectile types are presented. All tests were conducted at the Los Alamos explosive magnetic-flux compression facility in Ancho Canyon. The data suggest that the high-strength projectiles have lower resistance to acceleration than the low strength projectiles, which expand against the bore during acceleration. The railguns were powered by explosive magneticflux compression generators. Calculations to predict railgun and power supply performance were performed by Kerrisk

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

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

    DEFF Research Database (Denmark)

    Mortensen, Kell; Tomkiewicz, Yaffa; Bechgaard, Klaus

    1982-01-01

    The anisotropy in the static magnetic susceptibility of bis-tetramethyltetraselenafulvalene hexafluoroarsenate [(TMTSF)2AsF6] has been investigated above and below the metal-to-insulator transition for a range of fields between 0.5 and 30 kG. The results are consistent with the expectations of a ...

  6. 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

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

    International Nuclear Information System (INIS)

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

    1984-01-01

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

  8. 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

  9. Application of High Pressure in Food Processing

    Directory of Open Access Journals (Sweden)

    Herceg, Z.

    2011-01-01

    Full Text Available In high pressure processing, foods are subjected to pressures generally in the range of 100 – 800 (1200 MPa. The processing temperature during pressure treatments can be adjusted from below 0 °C to above 100 °C, with exposure times ranging from a few seconds to 20 minutes and even longer, depending on process conditions. The effects of high pressure are system volume reduction and acceleration of reactions that lead to volume reduction. The main areas of interest regarding high-pressure processing of food include: inactivation of microorganisms, modification of biopolymers, quality retention (especially in terms of flavour and colour, and changes in product functionality. Food components responsible for the nutritive value and sensory properties of food remain unaffected by high pressure. Based on the theoretical background of high-pressure processing and taking into account its advantages and limitations, this paper aims to show its possible application in food processing. The paper gives an outline of the special equipment used in highpressure processing. Typical high pressure equipment in which pressure can be generated either by direct or indirect compression are presented together with three major types of high pressure food processing: the conventional (batch system, semicontinuous and continuous systems. In addition to looking at this technology’s ability to inactivate microorganisms at room temperature, which makes it the ultimate alternative to thermal treatments, this paper also explores its application in dairy, meat, fruit and vegetable processing. Here presented are the effects of high-pressure treatment in milk and dairy processing on the inactivation of microorganisms and the modification of milk protein, which has a major impact on rennet coagulation and curd formation properties of treated milk. The possible application of this treatment in controlling cheese manufacture, ripening and safety is discussed. The opportunities

  10. 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

  11. 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.

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

    International Nuclear Information System (INIS)

    1984-10-01

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

  13. 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.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  15. 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.

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

    International Nuclear Information System (INIS)

    Hinatsu, Y.; Fujino, T.

    1988-01-01

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

  17. Modeling High Pressure Micro Hollow Cathode Discharges

    National Research Council Canada - National Science Library

    Boeuf, Jean-Pierre; Pitchford, Leanne

    2004-01-01

    This report results from a contract tasking CPAT as follows: The Grantee will perform theoretical modeling of point, surface, and volume high-pressure plasmas created using Micro Hollow Cathode Discharge sources...

  18. High Pressure EVA Glove (HPEG), Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Final Frontier Design's (FFD) High Pressure EVA Glove (HPEG) is a game changing technology enabling future exploration class space missions. The high operating...

  19. High-pressure phase transitions of strontianite

    Science.gov (United States)

    Speziale, S.; Biedermann, N.; Reichmann, H. J.; Koch-Mueller, M.; Heide, G.

    2015-12-01

    Strontianite (SrCO3) is isostructural to aragonite, a major high-pressure polymorph of calcite. Thus it is a material of interest to investigate the high-pressure phase behavior of aragonite-group minerals. SrCO3 is a common component of natural carbonates and knowing its physical properties at high pressures is necessary to properly model the thermodynamic properties of complex carbonates, which are major crustal minerals but are also present in the deep Earth [Brenker et al., 2007] and control carbon cycling in the Earth's mantle. The few available high-pressure studies of SrCO3 disagree regarding both pressure stability and structure of the post-aragonite phase [Lin & Liu, 1997; Ono et al., 2005; Wang et al. 2015]. To clarify such controversies we investigated the high-pressure behavior of synthetic SrCO3 by Raman spectroscopy. Using a diamond anvil cell we compressed single-crystals or powder of strontianite (synthesized at 4 GPa and 1273 K for 24h in a multi anvil apparatus), and measured Raman scattering up to 78 GPa. SrCO3 presents a complex high-pressure behavior. We observe mode softening above 20 GPa and a phase transition at 25 - 26.9 GPa, which we interpret due to the CO3 groups rotation, in agreement with Lin & Liu [1997]. The lattice modes in the high-pressure phase show dramatic changes which may indicate a change from 9-fold coordinated Sr to a 12-fold-coordination [Ono, 2007]. Our results confirm that the high-pressure phase of strontianite is compatible with Pmmn symmetry. References Brenker, F.E. et al. (2007) Earth and Planet. Sci. Lett., 260, 1; Lin, C.-C. & Liu, L.-G. (1997) J. Phys. Chem. Solids, 58, 977; Ono, S. et al. (2005) Phys. Chem. Minerals, 32, 8; Ono, S. (2007) Phys. Chem. Minerals, 34, 215; Wang, M. et al. (2015) Phys Chem Minerals 42, 517.

  20. High-pressure portable pneumatic drive unit.

    Science.gov (United States)

    Hete, B F; Savage, M; Batur, C; Smith, W A; Golding, L A; Nosé, Y

    1989-12-01

    The left ventricular assist device (LVAD) of the Cleveland Clinic Foundation (CCF) is a single-chamber assist pump, driven by a high-pressure pneumatic cylinder. A low-cost, portable driver that will allow cardiac care patients, with a high-pressure pneumatic ventricle assist, more freedom of movement has been developed. The compact and light-weight configuration can provide periods of 2 h of freedom from a fixed position driver and does not use exotic technology.

  1. High pressure effects on fruits and vegetables

    OpenAIRE

    Timmermans, R.A.H.; Matser, A.M.

    2016-01-01

    The chapter provides an overview on different high pressure based treatments (high pressure pasteurization, blanching, pressure-assisted thermal processing, pressure-shift freezing and thawing) available for the preservation of fruits and vegetable products and extending their shelf life. Pressure treatment can be used for product modification through pressure gelatinization of starch and pressure denaturation of proteins. Key pressure–thermal treatment effects on vitamin, enzymes, flavor, co...

  2. Studies on synthesis of diamond at high pressure and temperature

    Science.gov (United States)

    Kailath, Ansu J.

    chapter is a general introduction incorporating the information regarding diamond together with a brief history of diamond synthesis. It also includes the details of the high pressure synthesis of diamond, the uses of diamond grits, the advantages of the synthetic diamond grit over natural grit and an outline to elucidate the reasons which prompted to undertake the present work. The details of the technique used in the present studies for synthesis of diamond grits by high-pressure high-temperature process are included in chapter II. The hydraulic press used for synthesis, the details of the reactant materials, stacking of the high pressure cell and the details of synthesis run have been described together with the separation procedure to isolate diamond grits from the frozen slug. Different analytical and characterization techniques used in the present studies for the analysis and characterization of the reactant materials, synthesized diamonds and the crystallization medium have been illustrated in chapter III. The effect of different synthesizing parameters on synthesized diamond crystals were studied. This study includes: (a) dependence of yield of diamond on temperature and pressure, (b) dependence of crystal size on cook length, (c) effect of variation of the relative amounts of carbonaceous material and catalyst on synthesis, (d) morphological variation and (e) effect of pressure pulse on synthesized crystals. Various observations made during this study and the results obtained have been compiled in chapter IV. The synthesized diamond crystals were characterized by X-ray Powder Diffraction (XRD), Raman Spectroscopy, Scanning Electron Microscopy (SEM) and Optical Microscopy. The results obtained have been compiled in chapter V. In addition to these, the results obtained from the Infrared Spectra and the Electron Paramagnetic Spectra have also been included. Studies of crystallization medium and inclusions in the synthesized diamonds were carried out. This include

  3. High pressure X-ray studies

    International Nuclear Information System (INIS)

    Sikka, S.K.

    1981-01-01

    High pressure research has already led to new insights in the physical properties of materials and at times to the synthesis of new ones. In all this, X-ray diffraction has been a valuable diagnostic experimental tool. In particular, X-rays in high pressure field have been used (a) for crystallographic identification of high pressure polymorphs and (b) for study of the effect of pressure on lattice parameters and volume under isothermal conditions. The results in the area (a) are reviewed. The techniques of applying high pressures are described. These include both static and dynamic shockwave X-ray apparatus. To illustrate the effect of pressure, some of the pressure induced phase transitions in pure metals are described. It has been found that there is a clear trend for elements in any group of the periodic table to adopt similar structures at high pressures. These studies have enabled to construct generalized phase diagrams for many groups. In the case of alloys, the high pressure work done on Ti-V alloys is presented. (author)

  4. 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

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  6. 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.

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

    International Nuclear Information System (INIS)

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

    2004-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Jesper Hagemeier

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

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

    Directory of Open Access Journals (Sweden)

    Roger C. Searle

    2008-07-01

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

  10. Soil characterization using patterns of magnetic susceptibility versus effective radium concentration

    Directory of Open Access Journals (Sweden)

    F. Girault

    2011-08-01

    Full Text Available Low-field magnetic susceptibility χm and effective radium concentration ECRa, obtained from radon emanation, have been measured in the laboratory with 129 soil samples from Nepal. Samples along horizontal profiles in slope debris or terrace scarps showed rather homogeneous values of both χm and ECRa. One sample set, collected vertically on a lateritic terrace scarp, had homogeneous values of ECRa while χm increased by a factor of 1 to 10 for residual soils and topsoils. However, for a set of samples collected on three imbricated river terraces, values of ECRa, homogeneous over a given terrace, displayed a gradual increase from younger to older terraces. By contrast, χm showed more homogeneous mean values over the three terraces, with a larger dispersion, however, for the younger one. Similarly, Kathmandu sediments exhibited a large increase in ECRa from sand to clay layers, while χm increased moderately. The combination of χm and ECRa, thus, provides a novel tool to characterize quantitatively various soil groups and may be of interest to distinguish modes of alteration or deposition histories.

  11. Soil magnetic susceptibility: A quantitative proxy of soil drainage for use in ecological restoration

    Science.gov (United States)

    Grimley, D.A.; Wang, J.-S.; Liebert, D.A.; Dawson, J.O.

    2008-01-01

    Flooded, saturated, or poorly drained soils are commonly anaerobic, leading to microbially induced magnetite/maghemite dissolution and decreased soil magnetic susceptibility (MS). Thus, MS is considerably higher in well-drained soils (MS typically 40-80 ?? 10-5 standard international [SI]) compared to poorly drained soils (MS typically 10-25 ?? 10-5 SI) in Illinois, other soil-forming factors being equal. Following calibration to standard soil probings, MS values can be used to rapidly and precisely delineate hydric from nonhydric soils in areas with relatively uniform parent material. Furthermore, soil MS has a moderate to strong association with individual tree species' distribution across soil moisture regimes, correlating inversely with independently reported rankings of a tree species' flood tolerance. Soil MS mapping can thus provide a simple, rapid, and quantitative means for precisely guiding reforestation with respect to plant species' adaptations to soil drainage classes. For instance, in native woodlands of east-central Illinois, Quercus alba , Prunus serotina, and Liriodendron tulipifera predominantly occur in moderately well-drained soils (MS 40-60 ?? 10-5 SI), whereas Acer saccharinum, Carya laciniosa, and Fraxinus pennsylvanica predominantly occur in poorly drained soils (MS Urbana, IL, U.S.A.). Through use of soil MS maps calibrated to soil drainage class and native vegetation occurrence, restoration efforts can be conducted more successfully and species distributions more accurately reconstructed at the microecosystem level. ?? 2008 Society for Ecological Restoration International.

  12. 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.)

  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. 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

  16. 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.

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

    Science.gov (United States)

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

    2017-05-01

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

  18. High pressure synthesis of zeolite/polymer nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Haines, Julien; Thibaud, Jean-Marc; Rouquette, Jerome; Cambon, Olivier; Di Renzo, Francesco, E-mail: julien.haines@univ-montp2.fr [Institut Charles Gerhardt Montpellier (France); Lee, Arie van der [Institut Europeen des Membranes, Montpellier (France); Scelta, Demetrio; Ceppatelli, Matteo; Dziubek, Kamil; Gorelli, Federico; Bini, Roberto; Santoro, Mario [European Laboratory for Non Linear Spectroscopy, Firenze (Italy)

    2016-07-01

    Full text: Polymerization of simple organic molecules under high pressure in the subnanometric pores of pure SiO{sub 2} zeolites can be used to produce novel nanocomposite materials, which can be recovered at ambient P and have remarkable mechanical, electrical or optical properties. Polymerization of ethylene in silicalite was studied in situ at high pressure by IR and results in a nanocomposite with isolated chains of non-conducting polyethylene strongly confined in the pores based on single crystal x-ray diffraction data. The nanocomposite is much less compressible than silicalite and has a positive rather than a negative thermal expansion coefficient. In order to target novel electrical and optical properties, isolated chains of conducting polymers can also be prepared in the pores of zeolite hosts at high pressure, such as polyacetylene, which was polymerized under pressure in the pores of the 1-D zeolite TON. The structure of this nanocomposite was determined by synchrotron x-ray powder diffraction data with complete pore filling corresponding to one planar polymer chain confined in each pore with a zig-zag configuration in the yz plane. This very strong confinement can be expected to strongly modify the electrical properties of polyacetylene. In this nanocomposite, our theoretical calculations indicate that the electronic density of states of polyacetylene exhibit van Hove singularities related to quantum 1D confinement, which could lead to future technological applications. This new material is susceptible to have applications in nanoelectronics, nanophotonics and energy and light harvesting. Completely novel nanocomposites were prepared by the polymerization of carbon monoxide CO in silicalite and TON. In these materials, isolated, ideal polycarbonyl chains are obtained in contrast to the non-stoichiometric, branched bulk polymers obtained by high pressure polymerization of this simple system. These poly CO/zeolite composites could be interesting energetic

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

    Science.gov (United States)

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

    2011-09-01

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

  20. On high-pressure melting of tantalum

    Science.gov (United States)

    Luo, Sheng-Nian; Swift, Damian C.

    2007-01-01

    The issues related to high-pressure melting of Ta are discussed within the context of diamond-anvil cell (DAC) and shock wave experiments, theoretical calculations and common melting models. The discrepancies between the extrapolations of the DAC melting curve and the melting point inferred from shock wave experiments, cannot be reconciled either by superheating or solid-solid phase transition. The failure to reproduce low-pressure DAC melting curve by melting models such as dislocation-mediated melting and the Lindemann law, and molecular dynamics and quantum mechanics-based calculations, undermines their predictions at moderate and high pressures. Despite claims to the contrary, the melting curve of Ta (as well as Mo and W) remains inconclusive at high pressures.

  1. High-pressure boron hydride phases

    International Nuclear Information System (INIS)

    Barbee, T.W. III; McMahan, A.K.; Klepeis, J.E.; van Schilfgaarde, M.

    1997-01-01

    The stability of boron-hydrogen compounds (boranes) under pressure is studied from a theoretical point of view using total-energy methods. We find that the molecular forms of boranes known to be stable at ambient pressure become unstable at high pressure, while structures with extended networks of bonds or metallic bonding are energetically favored at high pressures. If such structures are metastable on return to ambient pressure, they would be energetic as well as dense hydrogen storage media. An AlH 3 -like structure of BH 3 is particularly interesting in that it may be accessible by high-pressure diamond anvil experiments, and should exhibit both second-order structural and metal-insulator transitions at lower pressures. copyright 1997 The American Physical Society

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-03-01

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

  3. 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.

  4. 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.

  5. High pressure freon decontamination of remote equipment

    International Nuclear Information System (INIS)

    Wilson, C.E.

    1987-01-01

    A series of decontamination tests using high pressure FREON 113 was conducted in the 200 Area of the Hanford site. The intent of these tests was to evaluate the effectiveness of FREON 113 in decontamination of manipulator components, tools, and equipment items contaminated with mixed fission products. The test results indicated that high pressure FREON 113 is very effective in removing fissile material from a variety of objects and can reduce both the quantity and the volume of the radioactive waste material presently being buried

  6. Techniques in high pressure neutron scattering

    CERN Document Server

    Klotz, Stefan

    2013-01-01

    Drawing on the author's practical work from the last 20 years, Techniques in High Pressure Neutron Scattering is one of the first books to gather recent methods that allow neutron scattering well beyond 10 GPa. The author shows how neutron scattering has to be adapted to the pressure range and type of measurement.Suitable for both newcomers and experienced high pressure scientists and engineers, the book describes various solutions spanning two to three orders of magnitude in pressure that have emerged in the past three decades. Many engineering concepts are illustrated through examples of rea

  7. High pressure water jet cutting and stripping

    Science.gov (United States)

    Hoppe, David T.; Babai, Majid K.

    1991-01-01

    High pressure water cutting techniques have a wide range of applications to the American space effort. Hydroblasting techniques are commonly used during the refurbishment of the reusable solid rocket motors. The process can be controlled to strip a thermal protective ablator without incurring any damage to the painted surface underneath by using a variation of possible parameters. Hydroblasting is a technique which is easily automated. Automation removes personnel from the hostile environment of the high pressure water. Computer controlled robots can perform the same task in a fraction of the time that would be required by manual operation.

  8. High pressure water jet mining machine

    Science.gov (United States)

    Barker, Clark R.

    1981-05-05

    A high pressure water jet mining machine for the longwall mining of coal is described. The machine is generally in the shape of a plowshare and is advanced in the direction in which the coal is cut. The machine has mounted thereon a plurality of nozzle modules each containing a high pressure water jet nozzle disposed to oscillate in a particular plane. The nozzle modules are oriented to cut in vertical and horizontal planes on the leading edge of the machine and the coal so cut is cleaved off by the wedge-shaped body.

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

    Science.gov (United States)

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

    2016-01-11

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

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

    Science.gov (United States)

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

    2010-12-01

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

  11. 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.

  12. High pressure study of high-temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Souliou, Sofia-Michaela

    2014-09-29

    Imm2). The structural transition is clearly reflected in the high pressure Raman data through the appearance of several new modes, allowing us to map in detail the (P,T) phase diagram and determine the transition line between the two phases. In the new phase, the renormalization of the buckling mode is completely suppressed, while no anomalies are observed in any of the other Raman active phonons. According to ab initio calculations, the coupling of the buckling mode to the electronic system is not significantly affected by the structural phase transition. The absence of phonon renormalizations in the presence of sizable electron-phonon coupling, indicate that, in contrast to earlier transport studies, YBa{sub 2}Cu{sub 4}O{sub 8} is not superconducting anymore under hydrostatic pressures higher than 10 GPa. Finally we proceeded with the investigation of the high pressure structural and vibrational properties of SmFeAsO, a member of the ''1111'' family (space group P4/nmm) of the Fe-based superconductors, in which superconductivity is commonly induced either by substituting F/H for O or by applying high pressures on the parent magnetic compound. The magnetic transition of the undoped compound is accompanied with a tetragonal-to-orthorhombic structural distortion, both of which are commonly suppressed upon the emergence of superconductivity. In the SmFeAsO{sub x}F{sub 1-x} system while the magnetic transition is totally suppressed already at low doping levels, structural studies have reported either the gradual suppression of the orthorhombic distortion or its retention over a wide regime of the superconducting phase. We addressed this controversy using high pressure as an alternative tuning parameter to suppress the magneto-structural transition and induce superconductivity in the parent compound. Our high pressure, low temperature X-ray diffraction measurements on single crystals of SmFeAsO have revealed that the tetragonal

  13. High pressure study of high-temperature superconductors

    International Nuclear Information System (INIS)

    Souliou, Sofia-Michaela

    2014-01-01

    Raman data through the appearance of several new modes, allowing us to map in detail the (P,T) phase diagram and determine the transition line between the two phases. In the new phase, the renormalization of the buckling mode is completely suppressed, while no anomalies are observed in any of the other Raman active phonons. According to ab initio calculations, the coupling of the buckling mode to the electronic system is not significantly affected by the structural phase transition. The absence of phonon renormalizations in the presence of sizable electron-phonon coupling, indicate that, in contrast to earlier transport studies, YBa 2 Cu 4 O 8 is not superconducting anymore under hydrostatic pressures higher than 10 GPa. Finally we proceeded with the investigation of the high pressure structural and vibrational properties of SmFeAsO, a member of the ''1111'' family (space group P4/nmm) of the Fe-based superconductors, in which superconductivity is commonly induced either by substituting F/H for O or by applying high pressures on the parent magnetic compound. The magnetic transition of the undoped compound is accompanied with a tetragonal-to-orthorhombic structural distortion, both of which are commonly suppressed upon the emergence of superconductivity. In the SmFeAsO x F 1-x system while the magnetic transition is totally suppressed already at low doping levels, structural studies have reported either the gradual suppression of the orthorhombic distortion or its retention over a wide regime of the superconducting phase. We addressed this controversy using high pressure as an alternative tuning parameter to suppress the magneto-structural transition and induce superconductivity in the parent compound. Our high pressure, low temperature X-ray diffraction measurements on single crystals of SmFeAsO have revealed that the tetragonal-to-orthorhombic transition survives with the application of high pressures up to 85 kbars. In addition, our Raman data

  14. 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

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

    Science.gov (United States)

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

    2014-12-01

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

  16. 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 ( 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.

  17. 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.

  18. 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.

  19. Magnetic susceptibilities and thermal expansion of artificial graphites; Susceptibilites magnetiques et dilatation thermique des graphites artificiels

    Energy Technology Data Exchange (ETDEWEB)

    Cornuault, P; Herpin, A; Hering, H; Seguin, M [Commissariat a l' Energie Atomique, Paris (France); Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    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) [French] En partant des mesures de la susceptibilite magnetique faites dans les directions des axes principaux d'un barreau de graphite, on a calcule la fonction de distribution des perpendiculaires aux plans graphitiques dans les cristallites. On a etudie les effets que pouvaient provoquer des modifications dans le procede de fabrication sur l'anisotropie cristalline. En considerant cette anisotropie cristalline, nous avons calcule le coefficient de dilatation thermique pour un bloc compact de cristallites ayant exactement la meme anisotropie d'orientation que le corps poreux en question. La difference entre cette valeur et celle mesuree du coefficient de dilatation, nous permet de calculer la dilatation pour la partie non-graphitique du bloc, en l'occurence, on trouve une valeur negative du coefficient pour cette partie, qui est egalement anisotropique. On a essaye d'en tirer quelques conclusions. (auteur)

  20. High-Pressure Synthesis, Structure, and Magnetic Properties of Ge-Substituted Filled Skutterudite Compounds; LnxCo4Sb12−yGey, Ln = La, Ce, Pr, and Nd

    Directory of Open Access Journals (Sweden)

    Hiroshi Fukuoka

    2017-12-01

    Full Text Available A series of new Ge-substituted skutterudite compounds with the general composition of LnxCo4Sb12−yGey, where Ln = La, Ce, Pr, and Nd, is prepared by high-pressure and high-temperature reactions at 7 GPa and 800 °C. They have a cubic unit cell and the lattice constant for each compound is 8.9504 (3, 8.94481 (6, 8.9458 (3, and 8.9509 (4 Å for the La, Ce, Pr, and Nd derivatives, respectively. Their chemical compositions, determined by electron prove microanalysis, are La0.57Co4Sb10.1Ge2.38, Ce0.99Co4Sb9.65Ge2.51, Pr0.97Co4Sb9.52Ge2.61, and Nd0.87Co4Sb9.94Ge2.28. Their structural parameters are refined by Rietveld analysis. The guest atom size does not affect the unit cell volume. The Co–Sb/Ge distance mainly determines the unit cell size as well as the size of guest atom site. The valence state of lanthanide ions is 3+.

  1. High Pressure Inactivation of HAV within Mussels

    Science.gov (United States)

    The potential of hepatitis A virus (HAV) to be inactivated within Mediterranean mussels (Mytilus galloprovincialis) and blue mussels (Mytilus edulis) by high pressure processing was evaluated. HAV was bioaccumulated within mussels to approximately 6-log10 PFU by exposure of mussels to HAV-contamina...

  2. Nucleation at high pressure I: Theoretical considerations.

    NARCIS (Netherlands)

    Luijten, C.C.M.; Dongen, van M.E.H.

    1999-01-01

    A theoretical approach is presented that accounts for the influence of high pressure background gases on the vapor-to-liquid nucleation process. The key idea is to treat the carrier gas pressure as a perturbation parameter that modifies the properties of the nucleating substance. Two important

  3. High pressure metrology for industrial applications

    Science.gov (United States)

    Sabuga, Wladimir; Rabault, Thierry; Wüthrich, Christian; Pražák, Dominik; Chytil, Miroslav; Brouwer, Ludwig; Ahmed, Ahmed D. S.

    2017-12-01

    To meet the needs of industries using high pressure technologies, in traceable, reliable and accurate pressure measurements, a joint research project of the five national metrology institutes and the university was carried out within the European Metrology Research Programme. In particular, finite element methods were established for stress-strain analysis of elastic and nonlinear elastic-plastic deformation, as well as of contact processes in pressure-measuring piston-cylinder assemblies, and high-pressure components at pressures above 1 GPa. New pressure measuring multipliers were developed and characterised, which allow realisation of the pressure scale up to 1.6 GPa. This characterisation is based on research including measurements of material elastic constants by the resonant ultrasound spectroscopy, hardness of materials of high pressure components, density and viscosity of pressure transmitting liquids at pressures up to 1.4 GPa and dimensional measurements on piston-cylinders. A 1.6 GPa pressure system was created for operation of the 1.6 GPa multipliers and calibration of high pressure transducers. A transfer standard for 1.5 GPa pressure range, based on pressure transducers, was built and tested. Herewith, the project developed the capability of measuring pressures up to 1.6 GPa, from which industrial users can calibrate their pressure measurement devices for accurate measurements up to 1.5 GPa.

  4. High pressure and synchrotron radiation satellite workshop

    Energy Technology Data Exchange (ETDEWEB)

    Bass, J.; Guignot, N.; Morard, G.; Mezouar, M.; Andrault, D.; Bolfan-Casanova, N.; Sturhahn, W.; Daniel, I.; Reynard, B.; Simionovici, A.; Sanchez Valle, C.; Martinez, I.; Kantor, I.; Dubrovinsky, I.; Mccammon, C.; Dubrovinskaia, N.; Kurnosiv, A.; Kuznetsov, A.; Goncharenko, I.; Loubeyre, P.; Desgreniers, S.; Weck, G.; Yoo, C.S.; Iota, V.; Park, J.; Cynn, H.; Gorelli, F.; Toulemonde, P.; Machon, D.; Merlen, A.; San Miguel, A.; Amboage, M.; Aquilanti, G.; Mathon, O.; Pascarelli, S.; Itie, J.P.; Mcmillan, P.F.; Trapananti, A.; Di Cicco, A.; Panfilis, S. de; Filipponi, A.; Kreisel, J.; Bouvier, P.; Dkhil, B.; Chaabane, B.; Rosner, H.; Koudela, D.; Schwarz, U.; Handestein, A.; Hanfland, M.; Opahle, I.; Koepernik, K.; Kuzmin, M.; Mueller, K.H.; Mydosh, J.; Richter, M.; Hejny, C.; Falconi, S.; Lundegaard, L.F.; Mcmahon, M.I; Loa, I.; Syassen, K.; Wang, X.; Roth, H.; Lorenz, T.; Farber Daniel, I.; Antonangeli Daniele, I.; Krisch, M.; Badro, J.; Fiquet, G.; Occelli, F.; Mao, W.L.; Mao, H.K.; Eng, P.; Kao, C.C.; Shu, J.F.; Hemley, R.J.; Tse, J.S.; Yao, Y.; Deen, P.P.; Paolasini, I.; Braithwaite, D.; Kernavanois, N.; Lapertot, G.; Rupprecht, K.; Leupold, O.; Ponkratz, U.; Wortmann, G.; Beraud, A.; Krisch, M.; Farber, D.; Antonangeli, D.; Aracne, C.; Zarestky, J.L.; Mcqueeney, R.; Mathon, O.; Baudelet, F.; Decremps, F.; Itie, J.P.; Nataf, I.; Pascarelli, S.; Polian, A

    2006-07-01

    The workshop is dedicated to recent advances on science at high pressure at third generation synchrotron sources. A variety of experiments using synchrotron radiation techniques including X-ray diffraction, EXAFS (extended X-ray absorption fine structure), inelastic X-ray scattering, Compton scattering and Moessbauer spectroscopy of crystalline, liquid or amorphous samples, are reported. This document gathers the abstracts of the presentations.

  5. High-pressure differential scanning microcalorimeter.

    Science.gov (United States)

    Senin, A A; Dzhavadov, L N; Potekhin, S A

    2016-03-01

    A differential scanning microcalorimeter for studying thermotropic conformational transitions of biopolymers at high pressure has been designed. The calorimeter allows taking measurements of partial heat capacity of biopolymer solutions vs. temperature at pressures up to 3000 atm. The principles of operation of the device, methods of its calibration, as well as possible applications are discussed.

  6. High-pressure oxidation of methane

    NARCIS (Netherlands)

    Hashemi, Hamid; Christensen, Jakob M.; Gersen, Sander; Levinsky, Howard; Klippenstein, Stephen J.; Glarborg, Peter

    2016-01-01

    Methane oxidation at high pressures and intermediate temperatures was investigated in a laminar flow reactor and in a rapid compression machine (RCM). The flow-reactor experiments were conducted at 700–900 K and 100 bar for fuel-air equivalence ratios (Φ) ranging from 0.06 to 19.7, all highly

  7. Study of ceramics sintering under high pressures

    International Nuclear Information System (INIS)

    Kunrath Neto, A.O.

    1990-01-01

    A systematic study was made on high pressure sintering of ceramics in order to obtain materials with controlled microstructure, which are not accessible by conventional methods. Some aspects with particular interest were: to achieve very low porosity, with fine grains; to produce dispersed metastable and denser phases which can act as toughening agents; the study of new possibilities for toughening enhancement. (author)

  8. High pressure synthesis of bismuth disulfide

    DEFF Research Database (Denmark)

    Søndergaard-Pedersen, Simone; Nielsen, Morten Bormann; Bremholm, Martin

    In this research the BiS2 compound was synthesized by a high pressure and high temperature method using a multi-anvil large volume press and the structure was solved by single crystal diffraction. The structure contains Bi atoms in distorted square-based pyramidal coordination to five surrounding...

  9. Analysis of high-pressure safety valves

    NARCIS (Netherlands)

    Beune, A.

    2009-01-01

    In presently used safety valve sizing standards the gas discharge capacity is based on a nozzle flow derived from ideal gas theory. At high pressures or low temperatures real gas effects can no longer be neglected, so the discharge coefficient corrected for flow losses cannot be assumed constant

  10. High pressure studies of planetary matter

    International Nuclear Information System (INIS)

    Ross, M.

    1989-06-01

    Those materials which are of greatest interest to the physics of the deep planetary interiors are Fe, H 2 , He and the Ices. These are sufficiently diverse and intensively studied to offer an overview of present day high pressure research. 13 refs., 1 fig

  11. High pressure and synchrotron radiation satellite workshop

    International Nuclear Information System (INIS)

    Bass, J.; Guignot, N.; Morard, G.; Mezouar, M.; Andrault, D.; Bolfan-Casanova, N.; Sturhahn, W.; Daniel, I.; Reynard, B.; Simionovici, A.; Sanchez Valle, C.; Martinez, I.; Kantor, I.; Dubrovinsky, I.; Mccammon, C.; Dubrovinskaia, N.; Kurnosiv, A.; Kuznetsov, A.; Goncharenko, I.; Loubeyre, P.; Desgreniers, S.; Weck, G.; Yoo, C.S.; Iota, V.; Park, J.; Cynn, H.; Gorelli, F.; Toulemonde, P.; Machon, D.; Merlen, A.; San Miguel, A.; Amboage, M.; Aquilanti, G.; Mathon, O.; Pascarelli, S.; Itie, J.P.; Mcmillan, P.F.; Trapananti, A.; Di Cicco, A.; Panfilis, S. de; Filipponi, A.; Kreisel, J.; Bouvier, P.; Dkhil, B.; Chaabane, B.; Rosner, H.; Koudela, D.; Schwarz, U.; Handestein, A.; Hanfland, M.; Opahle, I.; Koepernik, K.; Kuzmin, M.; Mueller, K.H.; Mydosh, J.; Richter, M.; Hejny, C.; Falconi, S.; Lundegaard, L.F.; Mcmahon, M.I; Loa, I.; Syassen, K.; Wang, X.; Roth, H.; Lorenz, T.; Farber Daniel, I.; Antonangeli Daniele, I.; Krisch, M.; Badro, J.; Fiquet, G.; Occelli, F.; Mao, W.L.; Mao, H.K.; Eng, P.; Kao, C.C.; Shu, J.F.; Hemley, R.J.; Tse, J.S.; Yao, Y.; Deen, P.P.; Paolasini, I.; Braithwaite, D.; Kernavanois, N.; Lapertot, G.; Rupprecht, K.; Leupold, O.; Ponkratz, U.; Wortmann, G.; Beraud, A.; Krisch, M.; Farber, D.; Antonangeli, D.; Aracne, C.; Zarestky, J.L.; Mcqueeney, R.; Mathon, O.; Baudelet, F.; Decremps, F.; Itie, J.P.; Nataf, I.; Pascarelli, S.; Polian, A.

    2006-01-01

    The workshop is dedicated to recent advances on science at high pressure at third generation synchrotron sources. A variety of experiments using synchrotron radiation techniques including X-ray diffraction, EXAFS (extended X-ray absorption fine structure), inelastic X-ray scattering, Compton scattering and Moessbauer spectroscopy of crystalline, liquid or amorphous samples, are reported. This document gathers the abstracts of the presentations

  12. 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.

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

    International Nuclear Information System (INIS)

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

    1988-01-01

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

  14. Advanced Diagnostics for High Pressure Spray Combustion.

    Energy Technology Data Exchange (ETDEWEB)

    Skeen, Scott A.; Manin, Julien Luc; Pickett, Lyle M.

    2014-06-01

    The development of accurate predictive engine simulations requires experimental data to both inform and validate the models, but very limited information is presently available about the chemical structure of high pressure spray flames under engine- relevant conditions. Probing such flames for chemical information using non- intrusive optical methods or intrusive sampling techniques, however, is challenging because of the physical and optical harshness of the environment. This work details two new diagnostics that have been developed and deployed to obtain quantitative species concentrations and soot volume fractions from a high-pressure combusting spray. A high-speed, high-pressure sampling system was developed to extract gaseous species (including soot precursor species) from within the flame for offline analysis by time-of-flight mass spectrometry. A high-speed multi-wavelength optical extinction diagnostic was also developed to quantify transient and quasi-steady soot processes. High-pressure sampling and offline characterization of gas-phase species formed following the pre-burn event was accomplished as well as characterization of gas-phase species present in the lift-off region of a high-pressure n-dodecane spray flame. For the initial samples discussed in this work several species were identified, including polycyclic aromatic hydrocarbons (PAH); however, quantitative mole fractions were not determined. Nevertheless, the diagnostic developed here does have this capability. Quantitative, time-resolved measurements of soot extinction were also accomplished and the novel use of multiple incident wavelengths proved valuable toward characterizing changes in soot optical properties within different regions of the spray flame.

  15. Piston cylinder cell for high pressure ultrasonic pulse echo measurements

    Energy Technology Data Exchange (ETDEWEB)

    Kepa, M. W., E-mail: mkepa@staffmail.ed.ac.uk; Huxley, A. D. [SUPA, Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom); Ridley, C. J.; Kamenev, K. V. [Centre for Science at Extreme Conditions and School of Engineering, University of Edinburgh, Edinburgh EH9 3FD (United Kingdom)

    2016-08-15

    Ultrasonic techniques such as pulse echo, vibrating reed, or resonant ultrasound spectroscopy are powerful probes not only for studying elasticity but also for investigating electronic and magnetic properties. Here, we report on the design of a high pressure ultrasonic pulse echo apparatus, based on a piston cylinder cell, with a simplified electronic setup that operates with a single coaxial cable and requires sample lengths of mm only. The design allows simultaneous measurements of ultrasonic velocities and attenuation coefficients up to a pressure of 1.5 GPa. We illustrate the performance of the cell by probing the phase diagram of a single crystal of the ferromagnetic superconductor UGe{sub 2}.

  16. High pressure effect on the crystal and magnetic structure of Pr.sub.0.1./sub.Sr.sub.0.9./sub.MnO.sub.3./sub. manganite

    Czech Academy of Sciences Publication Activity Database

    Dang, N.T.; Kozlenko, D. P.; Kichanov, S.E.; Jirák, Zdeněk; Lukin, E.V.; Savenko, B. N.

    2012-01-01

    Roč. 6, č. 5 (2012), s. 817-820 ISSN 1027-4510 Institutional research plan: CEZ:AV0Z10100521 Keywords : phase-separation * double exchange * diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.359, year: 2012

  17. 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.

  18. 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

  19. 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.

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

    Science.gov (United States)

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

    2011-05-01

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

  1. Inspection technology for high pressure pipes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae H.; Lee, Jae C.; Eum, Heung S.; Choi, Yu R.; Moon, Soon S.; Jang, Jong H

    2000-02-01

    Various kinds of defects are likely to be occurred in the welds of high pressure pipes in nuclear power plants. Considering the recent accident of Zuruga nuclear power plant in Japan, reasonable policy is strongly requested for the high pressure pipe integrity. In this study, we developed the technologies to inspect pipe welds automatically. After development of scanning robot prototype in the first research year, we developed and implemented the algorithm of automatic tracking of the scanning robot along the weld line of the pipes. We use laser slit beam on weld area and capture the image using digital camera. Through processing of the captures image, we finally determine the weld line automatically. In addition, we investigated a new technology on micro systems for developing micro scanning robotic inspection of the pipe welds. The technology developed in this study is being transferred to the industry. (author)

  2. Radioresistance increase in polymers at high pressures

    International Nuclear Information System (INIS)

    Milinchuk, V.; Kirjukhin, V.; Klinshpont, E.

    1977-01-01

    The effect was studied of very high pressures ranging within 100 and 2,700 MPa on the radioresistance of polytetrafluoroethylene, polypropylene and polyethylene in gamma irradiation. For experiments industrial polymers in the shape of blocks, films and fibres were used. It is shown that in easily breakable polymers, such as polytetrafluoroethylene and polypropylene 1.3 to 2 times less free radicals are formed as a result of gamma irradiation and a pressure of 150 MPa than at normal pressure. The considerably reduced radiation-chemical formation of radicals and the destruction suppression by cross-linking in polymers is the evidence of the polymer radioresistance in irradiation at high pressures. (J.B.)

  3. High-pressure oxidation of methane

    DEFF Research Database (Denmark)

    Hashemi, Hamid; Christensen, Jakob Munkholt; Gersen, Sander

    2016-01-01

    Methane oxidation at high pressures and intermediate temperatures was investigated in a laminar flow reactor and in a rapid compression machine (RCM). The flow-reactor experiments were conducted at 700–900 K and 100 bar for fuel-air equivalence ratios (Φ) ranging from 0.06 to 19.7, all highly...... diluted in nitrogen. It was found that under the investigated conditions, the onset temperature for methane oxidation ranged from 723 K under reducing conditions to 750 K under stoichiometric and oxidizing conditions. The RCM experiments were carried out at pressures of 15–80 bar and temperatures of 800......–1250 K under stoichiometric and fuel-lean (Φ=0.5) conditions. Ignition delays, in the range of 1–100 ms, decreased monotonically with increasing pressure and temperature. A chemical kinetic model for high-pressure methane oxidation was established, with particular emphasis on the peroxide chemistry...

  4. High pressure photoinduced ring opening of benzene

    International Nuclear Information System (INIS)

    Ciabini, Lucia; Santoro, Mario; Bini, Roberto; Schettino, Vincenzo

    2002-01-01

    The chemical transformation of crystalline benzene into an amorphous solid (a-C:H) was induced at high pressure by employing laser light of suitable wavelengths. The reaction was forced to occur at 16 GPa, well below the pressure value (23 GPa) where the reaction normally occurs. Different laser sources were used to tune the pumping wavelength into the red wing of the first excited singlet state S 1 ( 1 B 2u ) absorption edge. Here the benzene ring is distorted, presenting a greater flexibility which makes the molecule unstable at high pressure. The selective pumping of the S 1 level, in addition to structural considerations, was of paramount importance to clarify the mechanism of the reaction

  5. Foaming Glass Using High Pressure Sintering

    DEFF Research Database (Denmark)

    Østergaard, Martin Bonderup; Petersen, Rasmus Rosenlund; König, Jakob

    Foam glass is a high added value product which contributes to waste recycling and energy efficiency through heat insulation. The foaming can be initiated by a chemical or physical process. Chemical foaming with aid of a foaming agent is the dominant industrial process. Physical foaming has two...... to expand. After heat-treatment foam glass can be obtained with porosities of 80–90 %. In this study we conduct physical foaming of cathode ray tube (CRT) panel glass by sintering under high pressure (5-25 MPa) using helium, nitrogen, or argon at 640 °C (~108 Pa s). Reheating a sample in a heating...... variations. One way is by saturation of glass melts with gas. The other involves sintering of powdered glass under a high gas pressure resulting in glass pellets with high pressure bubbles entrapped. Reheating the glass pellets above the glass transition temperature under ambient pressure allows the bubbles...

  6. High pressure injection injuries: an overview.

    Science.gov (United States)

    Fialkov, J A; Freiberg, A

    1991-01-01

    Injuries resulting from the use of high pressure injectors and spray guns are relatively rare; however, the potential tissue damage caused by the injury as well as the extent of the injury itself may go unrecognized by the primary physician. The purpose of this paper is to inform the emergency physician of the nature and standard management of this type of injury. A basic understanding of the pathophysiology of the high pressure injection injury (HPII) is essential in avoiding the mistakes in management that have been reported in the literature. The emergency management of the HPII includes: evaluation and immobilization, tetanus and antimicrobial prophylaxis, supportive and resuscitative measures, analgesia, and minimizing the time to definitive surgical treatment.

  7. Stress concentration effects in high pressure components

    International Nuclear Information System (INIS)

    Aller, J.E.

    1990-01-01

    This paper examines the stress concentration effects of sideholes in thick walled, high pressure cylinders. It has been shown that the theoretical stress concentration factor at the intersection of a small crossbore in a closed end, thick walled cylinder varies between 3.0 and 4.0. Tests have shown that this effect can be greatly reduced in practice by carefully radiusing the bore intersection and autofrettaging the cylinder. It has also been shown that the minimum stress concentration factor occurs when the main bore and sidehole or crossbore have the same diameter, and the radius of the intersection is approximately equal to the sidehole radius. When the bore and sidehole intersection angle decreases from 90 degrees, the stress concentration factor increases significantly. Knowledge of these fundamental relationships can be used in maintaining, as well ad designing, high pressure equipment

  8. High-pressure torsion of hafnium

    International Nuclear Information System (INIS)

    Edalati, Kaveh; Horita, Zenji; Mine, Yoji

    2010-01-01

    Pure Hf (99.99%) is processed by high-pressure torsion (HPT) under pressures of 4 and 30 GPa to form an ultrafine-grained structure with a gain size of ∼180 nm. X-ray diffraction analysis shows that, unlike Ti and Zr, no ω phase formation is detected after HPT processing even under a pressure of 30 GPa. A hydride formation is detected after straining at the pressure of 4 GPa. The hydride phase decomposes either by application of a higher pressure as 30 GPa or by unloading for prolong time after HPT processing. Microhardness, tensile and bending tests show that a high hardness (360 Hv) and an appreciable ductility (8%) as well as high tensile and bending strength (1.15 and 2.75 GPa, respectively) are achieved following the high-pressure torsion.

  9. Hydrogen - High pressure production and storage

    International Nuclear Information System (INIS)

    Lauretta, J.R

    2005-01-01

    The development of simple, safe and more and more efficient technologies for the production and the storage of hydrogen is necessary condition for the transition towards the economy of hydrogen.In this work the hydrogen production studies experimentally to high pressure by electrolysis of alkaline solutions without the intervention of compressing systems and its direct storage in safe containers.The made tests show that the process of electrolysis to high pressure is feasible and has better yield than to low pressure, and that is possible to solve the operation problems, with relatively simple technology.The preliminary studies and tests indicate that the system container that studied is immune to the outbreak and can have forms and very different sizes, nevertheless, to reach or to surpass the efficiency of storage of the conventional systems the investments necessary will be due to make to be able to produce aluminum alloy tubes of high resistance

  10. Malignancy assessment of brain tumours with magnetic resonance spectroscopy and dynamic susceptibility contrast MRI

    Energy Technology Data Exchange (ETDEWEB)

    Fayed, Nicolas; Davila, Jorge; Medrano, Jaime [Diagnostic Radiology Department, Clinica Quiron, Zaragoza (Spain); Olmos, Salvador [Instituto de Investigacion en Ingenieria de Aragon, Zaragoza (Spain)], E-mail: olmos@unizar.es

    2008-09-15

    Magnetic resonance imaging (MRI) is the most common and well-established imaging modality for evaluation of intracerebral neoplasms, but there are still some incompletely solved challenges, such as reliable distinction between high- and low-grade tumours, exact delineation of tumour extension, and discrimination between recurrent tumour and radiation necrosis. The aim of this study was to evaluate the contribution of two MRI techniques to non-invasively estimate brain tumour grade. Twenty-four patients referred to MRI examination were analyzed and diagnosed with single intra-axial brain tumour. Lastly, histopathological analysis was performed to verify tumour type. Ten patients presented low-grade gliomas, while the remaining patients showed high-grade tumours, including glioblastomas in eight cases, isolated metastases in four patients and two cases with anaplastic gliomas. MRI examinations were performed on a 1.5-T scanner (Signa, General Electric). The acquisition protocol included the following sequences: saggital T1-weighted localizer, axial T1- and T2-weighted MRI, single-voxel magnetic resonance spectroscopy (MRS), dynamic susceptibility contrast (DSC) MRI and contrast-enhanced T1-weighted MRI. MRS data was analyzed with standard software provided by the scanner manufacturer. The metabolite ratio with the largest significant difference between tumour grades was the choline/creatine (Ch/Cr) ratio with elevated values in high-grade gliomas and metastases. A Ch/Cr ratio equal or larger than 1.55 predicted malignancy grade with 92% sensitivity and 80% specificity. The area under the ROC curve was 0.92 (CI: 95%; 0.81-1). Regarding to perfusion parameters, relative cerebral blood volume (rCBV) maps were estimated from the MR signal intensity time series during bolus passage with two commercial software packages. Two different regions of interest (ROI) were used to evaluate rCBV: lesion centre and perilesional region. All rCBV values were normalized to CBV in a

  11. Malignancy assessment of brain tumours with magnetic resonance spectroscopy and dynamic susceptibility contrast MRI

    International Nuclear Information System (INIS)

    Fayed, Nicolas; Davila, Jorge; Medrano, Jaime; Olmos, Salvador

    2008-01-01

    Magnetic resonance imaging (MRI) is the most common and well-established imaging modality for evaluation of intracerebral neoplasms, but there are still some incompletely solved challenges, such as reliable distinction between high- and low-grade tumours, exact delineation of tumour extension, and discrimination between recurrent tumour and radiation necrosis. The aim of this study was to evaluate the contribution of two MRI techniques to non-invasively estimate brain tumour grade. Twenty-four patients referred to MRI examination were analyzed and diagnosed with single intra-axial brain tumour. Lastly, histopathological analysis was performed to verify tumour type. Ten patients presented low-grade gliomas, while the remaining patients showed high-grade tumours, including glioblastomas in eight cases, isolated metastases in four patients and two cases with anaplastic gliomas. MRI examinations were performed on a 1.5-T scanner (Signa, General Electric). The acquisition protocol included the following sequences: saggital T1-weighted localizer, axial T1- and T2-weighted MRI, single-voxel magnetic resonance spectroscopy (MRS), dynamic susceptibility contrast (DSC) MRI and contrast-enhanced T1-weighted MRI. MRS data was analyzed with standard software provided by the scanner manufacturer. The metabolite ratio with the largest significant difference between tumour grades was the choline/creatine (Ch/Cr) ratio with elevated values in high-grade gliomas and metastases. A Ch/Cr ratio equal or larger than 1.55 predicted malignancy grade with 92% sensitivity and 80% specificity. The area under the ROC curve was 0.92 (CI: 95%; 0.81-1). Regarding to perfusion parameters, relative cerebral blood volume (rCBV) maps were estimated from the MR signal intensity time series during bolus passage with two commercial software packages. Two different regions of interest (ROI) were used to evaluate rCBV: lesion centre and perilesional region. All rCBV values were normalized to CBV in a

  12. Raman spectroscopy of triolein under high pressures

    Science.gov (United States)

    Tefelski, D. B.; Jastrzębski, C.; Wierzbicki, M.; Siegoczyński, R. M.; Rostocki, A. J.; Wieja, K.; Kościesza, R.

    2010-03-01

    This article presents results of the high pressure Raman spectroscopy of triolein. Triolein, a triacylglyceride (TAG) of oleic acid, is an unsaturated fat, present in natural oils such as olive oil. As a basic food component and an energy storage molecule, it has considerable importance for food and fuel industries. To generate pressure in the experiment, we used a high-pressure cylindrical chamber with sapphire windows, presented in (R.M. Siegoczyński, R. Kościesza, D.B. Tefelski, and A. Kos, Molecular collapse - modification of the liquid structure induced by pressure in oleic acid, High Press. Res. 29 (2009), pp. 61-66). Pressure up to 750 MPa was applied. A Raman spectrometer in "macro"-configuration was employed. Raman spectroscopy provides information on changes of vibrational modes related to structural changes of triolein under pressure. Interesting changes in the triglyceride C‒H stretching region at 2650-3100 cm-1 were observed under high-pressures. Changes were also observed in the ester carbonyl (C˭ O) stretching region 1700-1780 cm-1 and the C‒C stretching region at 1050-1150 cm-1. The overall luminescence of the sample decreased under pressure, making it possible to set longer spectrum acquisition time and obtain more details of the spectrum. The registered changes suggest that the high-pressure solid phase of triolein is organized as β-polymorphic, as was reported in (C. Akita, T. Kawaguchi, and F. Kaneko, Structural study on polymorphism of cis-unsaturated triacylglycerol: Triolein, J. Phys. Chem. B 110 (2006), pp. 4346-4353; E. Da Silva and D. Rousseau, Molecular order and thermodynamics of the solid-liquid transition in triglycerides via Raman spectroscopy, Phys. Chem. Chem. Phys. 10 (2008), pp. 4606-4613) (with temperature-induced phase transitions). The research has shown that Raman spectroscopy in TAGs under pressure reveals useful information about its structural changes.

  13. High Pressure Multicomponent Adsorption in Porous Media

    DEFF Research Database (Denmark)

    Shapiro, Alexander; Stenby, Erling Halfdan

    1999-01-01

    We analyse adsorption of a multicomponent mixture at high pressure on the basis of the potential theory of adsorption. The adsorbate is considered as a segregated mixture in the external field produced by a solid adsorbent. we derive an analytical equation for the thickness of a multicomponent fi...... close to a dew point. This equation (asymptotic adsorption equation, AAE) is a first order approximation with regard to the distance from a phase envelope....

  14. High pressure neutron powder diffraction at LANSCE

    International Nuclear Information System (INIS)

    Von Dreele, R.B.

    1994-01-01

    By making use of the recently developed ''Paris-Edinburgh'' high pressure cell, the author has successfully performed neutron powder experiments to 10GPa at ambient temperature. Results for the structural compression of the high Tc 1223-Hg superconductor to 9.2 GPa, the compression and possible hydrogen bond formation in brucite, Mg(OD) 2 , to 9.3 GPa, and the molecular reorientation in nitromethane to 5.5 GPa will be presented

  15. High-pressure mechanical instability in rocks.

    Science.gov (United States)

    Byerlee, J D; Brace, W F

    1969-05-09

    At a confining pressure of a few kilobars, deformation of many sedimentary rocks, altered mafic rocks, porous volcanic rocks, and sand is ductile, in that instabilities leading to audible elastic shocks are absent. At pressures of 7 to 10 kilobars, however, unstable faulting and stick-slip in certain of these rocks was observed. This high pressure-low temperature instability might be responsible for earthquakes in deeply buried sedimentary or volcanic sequences.

  16. observed by high pressure NMR and NQR

    Indian Academy of Sciences (India)

    Akogun, Hyogo 678-1297, Japan. ∗. Email: kohara@sci.himeji tech.ac.jp. Abstract. NMR and NQR studies on two interesting systems (URu2Si2, CeTIn5) were performed under high pressure. (1) URu2Si2: In the pressure range 3.0 to 8.3 kbar, we have observed new 29Si. NMR signals arising from the antiferromagnetic ...

  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. Path Dependency of High Pressure Phase Transformations

    Science.gov (United States)

    Cerreta, Ellen

    2017-06-01

    At high pressures titanium and zirconium are known to undergo a phase transformation from the hexagonal close packed (HCP), alpha-phase to the simple-hexagonal, omega-phase. Under conditions of shock loading, the high-pressure omega-phase can be retained upon release. It has been shown that temperature, peak shock stress, and texture can influence the transformation. Moreover, under these same loading conditions, plastic processes of slip and twinning are also affected by similar differences in the loading path. To understand this path dependency, in-situ velocimetry measurements along with post-mortem metallographic and neutron diffraction characterization of soft recovered specimens have been utilized to qualitatively understand the kinetics of transformation, quantify volume fraction of retained omega-phase and characterize the shocked alpha and omega-phases. Together the work described here can be utilized to map the non-equilibrium phase diagram for these metals and lend insight into the partitioning of plastic processes between phases during high pressure transformation. In collaboration with: Frank Addesssio, Curt Bronkhorst, Donald Brown, David Jones, Turab Lookman, Benjamin Morrow, Carl Trujillo, Los Alamos National Lab.; Juan Pablo Escobedo-Diaz, University of New South Wales; Paulo Rigg, Washington State University.

  19. High-Pressure Polymorphism in Orthoamphiboles

    Science.gov (United States)

    Finkelstein, G. J.; Zhang, D.; Shelton, H.; Dera, P.

    2017-12-01

    Amphiboles are double-chain silicate minerals that are the structurally hydrated counterpart to single-chain, anhydrous pyroxenes. They may play an important role in the earth as a carrier for volatiles in subduction zones, as well as a generator for seismic anisotropy in the upper mantle. Recent work has described previously unrecognized high-pressure polymorphism at low temperatures in a variety of pyroxene minerals, which may be relevant for the structure and dynamics of thick, cold, subducted slabs. However, high-pressure polymorphism in amphiboles above a few GPa in pressure has not been well explored, and if similar polymorphism to pyroxenes exists in this mineral family, it may affect the extent and depth of volatile transport in amphiboles, as well as their rheological properties. At low temperatures and high pressures, orthopyroxenes undergo crystal structure transitions at lower pressures than clinopyroxenes (10-30 GPa vs. > 50 GPa), so for this study we have investigated polymorphism in the anthophyllite-gedrite (Al-free and Al rich) orthoamphibole solid solution series. Using neon gas-loaded diamond anvil cells, we compressed both phases to a maximum pressure of 31 GPa, and observed transitions to new monoclinic structures in both endmembers. In this presentation, we will discuss the details of these transitions and implications for the earth's interior.

  20. Raman study of opal at high pressure

    Science.gov (United States)

    Farfan, G.; Wang, S.; Mao, W. L.

    2011-12-01

    More commonly known for their beauty and lore as gemstones, opals are also intriguing geological materials which may have potential for materials science applications. Opal lacks a definite crystalline structure, and is composed of an amorphous packing of hydrated silica (SiO2) spheroids, which provides us with a unique nano-scaled mineraloid with properties unlike those of other amorphous materials like glass. Opals from different localities were studied at high pressure using a diamond anvil cell to apply pressure and Raman spectroscopy to look at changes in bonding as pressure was increased. We first tested different samples from Virgin Valley, NV, Spencer, ID, Juniper Ridge, OR, and Australia, which contain varying amounts of water at ambient conditions, using Raman spectroscopy to determine if they were opal-CT (semicrystalline cristobalite-trydimite volcanic origin) or opal-A (amorphous sedimentary origin). We then used x-ray diffraction and Raman spectroscopy in a diamond anvil cell to see how their bonding and structure changed under compression and to determine what effect water content had on their high pressure behavior. Comparison of our results on opal to other high pressure studies of amorphous materials like glass has implications from a geological and materials science standpoint.

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

    International Nuclear Information System (INIS)

    Sercheli, Mauricio da Silva

    1999-01-01

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

  2. 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.

  3. Thermopower measurement under high pressure using 'seesaw heating method'

    International Nuclear Information System (INIS)

    Hedo, M; Nakamura, D; Takaesu, Y; Yagasaki, K; Nakama, T; Fujiwara, T; Uchima, K

    2010-01-01

    We have developed a set-up with modified 'seesaw heating method' for the thermopower measurement under pressures P up to 3 GPa at the temperature range between 2 K and 300 K. By using this set-up, the thermopower and electrical resistivity of the single crystalline YbMn 2 Ge 2 under high pressure were measured with enough accuracy. S(T) curve shows the characteristic feature at the magnetic transition in all pressure range, while no evidence of the magnetic phase transition is observed in ρ(T) at P > 1.25 GPa. The measurement results indicate that the simultaneous measurement of the thermopower and electrical resistivity is a useful tool to study the pressure-induced phase transitions.

  4. Energy Systems High-Pressure Test Laboratory | Energy Systems Integration

    Science.gov (United States)

    Facility | NREL Energy Systems High-Pressure Test Laboratory Energy Systems High-Pressure Test Laboratory In the Energy Systems Integration Facility's High-Pressure Test Laboratory, researchers can safely test high-pressure hydrogen components. Photo of researchers running an experiment with a hydrogen fuel

  5. 7 CFR 58.219 - High pressure pumps and lines.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false High pressure pumps and lines. 58.219 Section 58.219....219 High pressure pumps and lines. High pressure lines may be cleaned-in-place and shall be of such construction that dead ends, valves and the high pressure pumps can be disassembled for hand cleaning. The high...

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

    Science.gov (United States)

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

    2013-10-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-04-24

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

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

    International Nuclear Information System (INIS)

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

    1992-01-01

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

  9. 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

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

    Science.gov (United States)

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

    2016-03-01

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

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

    Science.gov (United States)

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

    2010-07-14

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

  12. 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)

  13. HIGH PRESSURE COAL COMBUSTON KINETICS PROJECT

    Energy Technology Data Exchange (ETDEWEB)

    Stefano Orsino

    2005-03-30

    As part of the U.S. Department of Energy (DoE) initiative to improve the efficiency of coal-fired power plants and reduce the pollution generated by these facilities, DOE has funded the High-Pressure Coal Combustion Kinetics (HPCCK) Projects. A series of laboratory experiments were conducted on selected pulverized coals at elevated pressures with the specific goals to provide new data for pressurized coal combustion that will help extend to high pressure and validate models for burnout, pollutant formation, and generate samples of solid combustion products for analyses to fill crucial gaps in knowledge of char morphology and fly ash formation. Two series of high-pressure coal combustion experiments were performed using SRI's pressurized radiant coal flow reactor. The first series of tests characterized the near burner flame zone (NBFZ). Three coals were tested, two high volatile bituminous (Pittsburgh No.8 and Illinois No.6), and one sub-bituminous (Powder River Basin), at pressures of 1, 2, and 3 MPa (10, 20, and 30 atm). The second series of experiments, which covered high-pressure burnout (HPBO) conditions, utilized a range of substantially longer combustion residence times to produce char burnout levels from 50% to 100%. The same three coals were tested at 1, 2, and 3 MPa, as well as at 0.2 MPa. Tests were also conducted on Pittsburgh No.8 coal in CO2 entrainment gas at 0.2, 1, and 2 MPa to begin establishing a database of experiments relevant to carbon sequestration techniques. The HPBO test series included use of an impactor-type particle sampler to measure the particle size distribution of fly ash produced under complete burnout conditions. The collected data have been interpreted with the help of CFD and detailed kinetics simulation to extend and validate devolatilization, char combustion and pollutant model at elevated pressure. A global NOX production sub-model has been proposed. The submodel reproduces the performance of the detailed chemical

  14. High-pressure oxidation of ethane

    DEFF Research Database (Denmark)

    Hashemi, Hamid; G. Jacobsen, Jon; Rasmussen, Christian T.

    2017-01-01

    Ethane oxidation at intermediate temperatures and high pressures has been investigated in both a laminar flow reactor and a rapid compression machine (RCM). The flow-reactor measurements at 600–900 K and 20–100 bar showed an onset temperature for oxidation of ethane between 700 and 825 K, depending...... on pressure, stoichiometry, and residence time. Measured ignition delay times in the RCM at pressures of 10–80 bar and temperatures of 900–1025 K decreased with increasing pressure and/or temperature. A detailed chemical kinetic model was developed with particular attention to the peroxide chemistry. Rate...

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

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

    NARCIS (Netherlands)

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

    2010-01-01

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

  18. 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.

  19. 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

  20. Measurement of susceptibility artifacts with histogram-based reference value on magnetic resonance images according to standard ASTM F2119.

    Science.gov (United States)

    Heinrich, Andreas; Teichgräber, Ulf K; Güttler, Felix V

    2015-12-01

    The standard ASTM F2119 describes a test method for measuring the size of a susceptibility artifact based on the example of a passive implant. A pixel in an image is considered to be a part of an image artifact if the intensity is changed by at least 30% in the presence of a test object, compared to a reference image in which the test object is absent (reference value). The aim of this paper is to simplify and accelerate the test method using a histogram-based reference value. Four test objects were scanned parallel and perpendicular to the main magnetic field, and the largest susceptibility artifacts were measured using two methods of reference value determination (reference image-based and histogram-based reference value). The results between both methods were compared using the Mann-Whitney U-test. The difference between both reference values was 42.35 ± 23.66. The difference of artifact size was 0.64 ± 0.69 mm. The artifact sizes of both methods did not show significant differences; the p-value of the Mann-Whitney U-test was between 0.710 and 0.521. A standard-conform method for a rapid, objective, and reproducible evaluation of susceptibility artifacts could be implemented. The result of the histogram-based method does not significantly differ from the ASTM-conform method.

  1. Strain engineered pyrochlore at high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Rittman, Dylan R.; Turner, Katlyn M.; Park, Sulgiye; Fuentes, Antonio F.; Park, Changyong; Ewing, Rodney C.; Mao, Wendy L.

    2017-05-22

    Strain engineering is a promising method for next-generation materials processing techniques. Here, we use mechanical milling and annealing followed by compression in diamond anvil cell to tailor the intrinsic and extrinsic strain in pyrochlore, Dy2Ti2O7 and Dy2Zr2O7. Raman spectroscopy, X-ray pair distribution function analysis, and X-ray diffraction were used to characterize atomic order over short-, medium-, and long-range spatial scales, respectively, under ambient conditions. Raman spectroscopy and X-ray diffraction were further employed to interrogate the material in situ at high pressure. High-pressure behavior is found to depend on the species and concentration of defects in the sample at ambient conditions. Overall, we show that defects can be engineered to lower the phase transformation onset pressure by ~50% in the ordered pyrochlore Dy2Zr2O7, and lower the phase transformation completion pressure by ~20% in the disordered pyrochlore Dy2Zr2O7. These improvements are achieved without significantly sacrificing mechanical integrity, as characterized by bulk modulus.

  2. Sounding experiments of high pressure gas discharge

    International Nuclear Information System (INIS)

    Biele, Joachim K.

    1998-01-01

    A high pressure discharge experiment (200 MPa, 5·10 21 molecules/cm 3 , 3000 K) has been set up to study electrically induced shock waves. The apparatus consists of the combustion chamber (4.2 cm 3 ) to produce high pressure gas by burning solid propellant grains to fill the electrical pump chamber (2.5 cm 3 ) containing an insulated coaxial electrode. Electrical pump energy up to 7.8 kJ at 10 kV, which is roughly three times of the gas energy in the pump chamber, was delivered by a capacitor bank. From the current-voltage relationship the discharge develops at rapidly decreasing voltage. Pressure at the combustion chamber indicating significant underpressure as well as overpressure peaks is followed by an increase of static pressure level. These data are not yet completely understood. However, Lorentz forces are believed to generate pinching with subsequent pinch heating, resulting in fast pressure variations to be propagated as rarefaction and shock waves, respectively. Utilizing pure axisymmetric electrode initiation rather than often used exploding wire technology in the pump chamber, repeatable experiments were achieved

  3. High Pressure and Temperature Effects in Polymers

    Science.gov (United States)

    Bucknall, David; Arrighi, Valeria; Johnston, Kim; Condie, Iain

    Elastomers are widely exploited as the basis for seals in gas and fluid pipelines. The underlying behaviour of these elastomer at the high pressure, elevated temperatures they experience in operation is poorly understood. Consequently, the duty cycle of these materials is often deliberately limited to a few hours, and in order to prevent failure, production is stopped in order to change the seals in critical joints. The result is significant time lost due to bringing down production to change the seals as well as knock on financial costs. In order to address the fundamental nature of the elastomers at their intended operating conditions, we are studying the gas permeation behaviour of hydrogenated natural butyl rubber (HNBR) and fluorinated elastomers (FKM) at a high pressure and elevated temperature. We have developed a pressure system that permits gas permeation studies at gas pressures of up to 5000 psi and operating temperatures up to 150° C. In this paper, we will discuss the nature of the permeation behaviour at these extreme operating conditions, and how this relates to the changes in the polymer structure. We will also discuss the use of graphene-polymer thin layer coatings to modify the gas permeation behaviour of the elastomers.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-06-15

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

  5. [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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1969-06-01

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

  7. Self-contained high-pressure chambers for study on the Moessbauer effect at low temperatures

    International Nuclear Information System (INIS)

    Stepanov, G.N.

    1980-01-01

    Designs of two high-pressure chambers intended for studying the Moessbauer effect at low temperatures are described. The high-pressure chamber of the Bridgman anvil type is made of non magnetic materials and intended for operation at helium temperatures. The chamber employs a superconducting pressure gage. A sample and superconducting pressure gage are surrounded with a liquid medium of a high pressure at a room temperature. Measurements of the pressure were taken during heating the chamber in the vapours of liquid helium according to the known dependence of the lead superconducting transition temperature on pressure. The other high-pressure chamber of the piston-to-cylinder type can be used to study the Moessbauer effect at temperatures ranging from 4 to 300 K. Pressure in the chamber is measured by means of the superconducting pressure gage. The maximum pressure obtained in the chamber constitutes 25 kbar

  8. Rare-earth-metal nitridophosphates through high-pressure metathesis

    International Nuclear Information System (INIS)

    Kloss, Simon David; Schnick, Wolfgang

    2015-01-01

    Developing a synthetic method to target an broad spectrum of unknown phases can lead to fascinating discoveries. The preparation of the first rare-earth-metal nitridophosphate LiNdP_4N_8 is reported. High-pressure solid-state metathesis between LiPN_2 and NdF_3 was employed to yield a highly crystalline product. The in situ formed LiF is believed to act both as the thermodynamic driving force and as a flux to aiding single-crystal formation in dimensions suitable for crystal structure analysis. Magnetic properties stemming from Nd"3"+ ions were measured by SQUID magnetometry. LiNdP_4N_8 serves as a model system for the exploration of rare-earth-metal nitridophosphates that may even be expanded to transition metals. High-pressure metathesis enables the systematic study of these uncharted regions of nitride-based materials with unprecedented properties. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Superconductivity in the unconventional high pressure phase bismuth-III

    Energy Technology Data Exchange (ETDEWEB)

    Semeniuk, Konstantin; Brown, Philip; Vasiljkovic, Aleksandar; Grosche, Malte [University of Cambridge (United Kingdom)

    2015-07-01

    One of the most surprising developments in high pressure research was the realisation that many elements assume very unexpected high pressure structures, described in terms of extremely large or even infinite unit cells. Elemental bismuth, which has been known to undergo a series of pressure induced structural transitions between 25 kbar and 80 kbar, is an interesting example: the intermediate pressure Bi-III phase has a complex 'host-guest' structure consisting of two incommensurate sublattices. Since the unit cell is infinitely large, the description of electronic and lattice excitations is problematic. Apart from its metallic character and the observation of superconductivity at low temperature, little is known about the electronic structure in this phase. We investigate the electrical resistivity within the metallic Bi-III phase under high hydrostatic pressure and in applied magnetic field using a piston cylinder cell. Superconductivity is observed below 7.1 K, and we extract the temperature dependence of the upper critical field, which exceeds 2 T at low temperature. The normal state resistivity exhibits an approximately linear temperature dependence. This could be attributed to strong scattering from low-lying excitations, as caused by an unusually soft phonon spectrum. The results suggest that strong coupling superconductivity arises within the host-guest structure of Bi-III out of an unusual electronic state.

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

    Science.gov (United States)

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

    2018-04-01

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

  11. 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

  12. Computer simulations of high pressure systems

    International Nuclear Information System (INIS)

    Wilkins, M.L.

    1977-01-01

    Numerical methods are capable of solving very difficult problems in solid mechanics and gas dynamics. In the design of engineering structures, critical decisions are possible if the behavior of materials is correctly described in the calculation. Problems of current interest require accurate analysis of stress-strain fields that range from very small elastic displacement to very large plastic deformation. A finite difference program is described that solves problems over this range and in two and three space-dimensions and time. A series of experiments and calculations serve to establish confidence in the plasticity formulation. The program can be used to design high pressure systems where plastic flow occurs. The purpose is to identify material properties, strength and elongation, that meet the operating requirements. An objective is to be able to perform destructive testing on a computer rather than on the engineering structure. Examples of topical interest are given

  13. The high-pressure behavior of bloedite

    DEFF Research Database (Denmark)

    Comodi, Paola; Nazzareni, Sabrina; Balic Zunic, Tonci

    2014-01-01

    High-pressure single-crystal synchrotron X‑ray diffraction was carried out on a single crystal of bloedite [Na2Mg(SO4)24H2O] compressed in a diamond-anvil cell. The volume-pressure data, collected up to 11.2 GPa, were fitted by a second- and a third-order Birch-Murnaghan equation of state (EOS....... Pressure decreases significantly the distortion of Na coordination. Up to 10 GPa, the donor-acceptor oxygen distances decrease significantly and the difference between the two water molecules decreases with an increase in the strengths of hydrogen bonds. At the same time, the bond lengths from Na and Mg...... to O atoms of the water molecules decrease faster than other bonds to these cations suggesting that there is a coupling between the Na-Ow and Mg-Ow bond strengths and the “hydrogen transfer” to acceptor O atoms....

  14. Urea and deuterium mixtures at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Donnelly, M., E-mail: m.donnelly-2@sms.ed.ac.uk; Husband, R. J.; Frantzana, A. D.; Loveday, J. S. [Centre for Science at Extreme Conditions and School of Physics and Astronomy, The University of Edinburgh, Erskine Williamson Building, Peter Guthrie Tait Road, The King’s Buildings, Edinburgh EH9 3FD (United Kingdom); Bull, C. L. [ISIS, Rutherford Appleton Laboratory, Oxford Harwell, Didcot OX11 0QX (United Kingdom); Klotz, S. [IMPMC, CNRS UMR 7590, Université P and M Curie, 4 Place Jussieu, 75252 Paris (France)

    2015-03-28

    Urea, like many network forming compounds, has long been known to form inclusion (guest-host) compounds. Unlike other network formers like water, urea is not known to form such inclusion compounds with simple molecules like hydrogen. Such compounds if they existed would be of interest both for the fundamental insight they provide into molecular bonding and as potential gas storage systems. Urea has been proposed as a potential hydrogen storage material [T. A. Strobel et al., Chem. Phys. Lett. 478, 97 (2009)]. Here, we report the results of high-pressure neutron diffraction studies of urea and D{sub 2} mixtures that indicate no inclusion compound forms up to 3.7 GPa.

  15. Sizing of high-pressure restriction orifices

    International Nuclear Information System (INIS)

    Casado Flores, E.

    1995-01-01

    Constant up-grading of power plants sometimes requires the modification of components which form part of suppliers' packages. In order to protect technology they have developed, however, the suppliers do not supply their calculation criteria. In order to reduce the costs of such improvements, and so as to be able to undertake the modification without having to rely on the original supplier, this paper describes the basic criteria applicable to the study of high-pressure restriction orifices, which can be considered to be representative of the components in question. The restriction orifices discussed are: - Insert - Multiplates in series with one perforation in each plate - Multiplates in series with several perforations in each plate For each type, an explanation of their sizing is given, together with the equations relating the corresponding flow and pressure drop. (Author)

  16. Recent developments in high pressure water technology

    International Nuclear Information System (INIS)

    Johnson, N.A.; Johnson, T.

    1992-01-01

    High Pressure Water Jetting has advanced rapidly in the last decade to a point where the field is splitting into specialised areas. This has left the end user or client in the dark as to whether water jetting will work and if so what equipment is best suited to their particular application. The aim of this paper is to give an overview of:-1. The way water is delivered to the surface and the parameters which control the concentration of energy available on impact. 2. The factors governing application driven selection of equipment. 3. The effects to technical advances in pumps and delivery systems on equipment selection with reference to their to their application to concrete removal and nuclear decontamination. (Author)

  17. SrWO4 at high pressures

    International Nuclear Information System (INIS)

    Grzechnik, A.; Crichton, W.A.; Hanfland, M.

    2005-01-01

    Room-temperature high-pressure behaviour of SrWO 4 scheelite (I4 1 /a, Z=4) has been studied to 20.7 GPa in a diamond anvil cell using synchrotron angle-dispersive X-ray powder diffraction. Above 10 GPa, it transforms to the fergusonite structure (I2/a, Z=4). Both scheelite and fergusonite types are ordered superstructures of fluorite (Fm anti 3m, Z=4). There is no significant volume collapse at the scheelite-fergusonite phase transition. However, the compression data including both phases of strontium tungstate cannot be fitted by a common Birch-Murnaghan equation of state. An onset of decomposition into component oxides occurs at about 15 GPa. The pressure-induced transformations are irreversible. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. High-pressure structures of methane hydrate

    International Nuclear Information System (INIS)

    Hirai, H; Uchihara, Y; Fujihisa, H; Sakashita, M; Katoh, E; Aoki, K; Yamamoto, Y; Nagashima, K; Yagi, T

    2002-01-01

    Three high-pressure structures of methane hydrate, a hexagonal structure (str. A) and two orthorhombic structures (str. B and str. C), were found by in situ x-ray diffractometry and Raman spectroscopy. The well-known structure I (str. I) decomposed into str. A and fluid at 0.8 GPa. Str. A transformed into str. B at 1.6 GPa, and str. B further transformed into str. C at 2.1 GPa which survived above 7.8 GPa. The fluid solidified as ice VI at 1.4 GPa, and the ice VI transformed to ice VII at 2.1 GPa. The bulk moduli, K 0 , for str. I, str. A, and str. C were calculated to be 7.4, 9.8, and 25.0 GPa, respectively

  19. High Pressure Quick Disconnect Particle Impact Tests

    Science.gov (United States)

    Rosales, Keisa R.; Stoltzfus, Joel M.

    2009-01-01

    NASA Johnson Space Center White Sands Test Facility (WSTF) performed particle impact testing to determine whether there is a particle impact ignition hazard in the quick disconnects (QDs) in the Environmental Control and Life Support System (ECLSS) on the International Space Station (ISS). Testing included standard supersonic and subsonic particle impact tests on 15-5 PH stainless steel, as well as tests performed on a QD simulator. This paper summarizes the particle impact tests completed at WSTF. Although there was an ignition in Test Series 4, it was determined the ignition was caused by the presence of a machining imperfection. The sum of all the test results indicates that there is no particle impact ignition hazard in the ISS ECLSS QDs. KEYWORDS: quick disconnect, high pressure, particle impact testing, stainless steel

  20. Dynamism or Disorder at High Pressures?

    Science.gov (United States)

    Angel, R. J.; Bismayer, U.; Marshall, W. G.

    2002-12-01

    Phase transitions in minerals at elevated temperatures typically involve dynamics as a natural consequence of the increase in thermal energy available to the system. Classic examples include quartz, cristobalite, and carbonates in which the high-temperature, high symmetry phase is dynamically disordered. This disorder has important thermodynamic consequences, including displacement and curvature of phase boundaries (e.g. calcite-aragonite). In other minerals such as clinopyroxenes and anorthite feldspar, the dynamic behaviour is restricted to the neighbourhood of the phase transition. The fundamental question is whether increasing pressure generally suppresses such dynamic behaviour (as in anorthite; Angel, 1988), or not. In the latter case it must be included in thermodynamic models of high-pressure phase equilibria and seismological modelling of the mantle; the potential dynamics and softening in stishovite may provide the critical observational constraint on the presence or otherwise of free silica in the lower mantle. We have continued to use the lead phosphate as a prototype ferroelastic in which to understand dynamic behaviour, simply because its dynamics and transition behaviour is far better characterised than any mineral. Furthermore, the phase transition is at a pressure where experimental difficulties do not dominate the experimental results. Our previous neutron diffraction study (Angel et al., 2001) revealed that some disorder, either dynamic or static, is retained in the high-symmetry, high-pressure phase just above the phase transition. New neutron diffraction data on the pure material now suggests that this disorder slowly decreases with increasing pressure until at twice the transition pressure it is ordered. Further data for doped material provides insights into the nature of this disorder. Angel (1988) Amer. Mineral. 73:1114. Angel et al (2001) J PhysC 13: 5353.

  1. 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

  2. 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.

  3. Development of a remote inspection robot for high pressure structures

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae C.; Kim, Jae H.; Choi, Yu R.; Moon, Soon S

    1999-10-01

    The high pressure structures in industrial plants must be periodically inspected for ensure their safety. Currently, the examination of them is manually performed by human inspectors, and there are many restrictions to examine the large containers which enclose dangerous chemicals or radioactive materials. We developed a remotely operated robot to examine these structures using recent mobile robot and computer technologies. Our robot has two magnetic caterpillars that make the robot can adhere to the structures made of steel like materials. The robot moves to the position for examination, and scans that position using ultrasonic probes equipped on it's arm, and transmits the result to the inspector according to his/her commands. Without building any auxiliary structures the robot can inspect the places where manual inspection can't reach. Therefore the robot can make shortening the inspection time as well as preventing the inspector from an accident. (author)

  4. High pressure microwave discharge for electrodeless Xe-lamp

    International Nuclear Information System (INIS)

    Kudela, J.; Kando, M.

    1998-01-01

    Preliminary results are presented of the investigation into the high pressure Xe microwave discharge in bent tubes, sustained by electromagnetic surface wave. The research was aimed to help with the design of a new generation of high intensity light sources with generally more complex shapes than those commonly used. The results show that the electromagnetic surface wave can effectively sustain discharge in tubes with various bending radii within the large pressure range. The curved shapes of discharge tubes improve the cooling of the lamp which is one of the major technological difficulties. It was shown that under relatively lower powers and higher gas pressures (100 Torr) the discharge exhibits a streamer-like filamentation and the branching of filaments. The phenomena of the effective sustaining of the discharge by surface wave propagation along curved plasma columns will be investigated in more detail by measurements of the profiles of surface wave electric and magnetic field intensities. (author)

  5. Development of a remote inspection robot for high pressure structures

    International Nuclear Information System (INIS)

    Lee, Jae C.; Kim, Jae H.; Choi, Yu R.; Moon, Soon S.

    1999-10-01

    The high pressure structures in industrial plants must be periodically inspected for ensure their safety. Currently, the examination of them is manually performed by human inspectors, and there are many restrictions to examine the large containers which enclose dangerous chemicals or radioactive materials. We developed a remotely operated robot to examine these structures using recent mobile robot and computer technologies. Our robot has two magnetic caterpillars that make the robot can adhere to the structures made of steel like materials. The robot moves to the position for examination, and scans that position using ultrasonic probes equipped on it's arm, and transmits the result to the inspector according to his/her commands. Without building any auxiliary structures the robot can inspect the places where manual inspection can't reach. Therefore the robot can make shortening the inspection time as well as preventing the inspector from an accident. (author)

  6. 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

  7. Experimental mathematics on the magnetic susceptibility of the square lattice Ising model

    Energy Technology Data Exchange (ETDEWEB)

    Boukraa, S [LPTHIRM and Departement d' Aeronautique, Universite de Blida (Algeria); Guttmann, A J; Jensen, I [ARC Centre of Excellence for Mathematics and Statistics of Complex Systems, Department of Mathematics and Statistics, University of Melbourne, Victoria 3010 (Australia); Hassani, S; Zenine, N [Centre de Recherche Nucleaire d' Alger, 2 Bd. Frantz Fanon, BP 399, 16000 Alger (Algeria); Maillard, J-M [LPTMC, Universite de Paris, Tour 24, 4eme etage, case 121, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Nickel, B [Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1 (Canada)], E-mail: boukraa@mail.univ-blida.dz, E-mail: tonyg@ms.unimelb.edu.au, E-mail: I.Jensen@ms.unimelb.edu.au, E-mail: maillard@lptmc.jussieu.fr, E-mail: maillard@lptl.jussieu.fr, E-mail: njzenine@yahoo.com

    2008-11-14

    We calculate very long low- and high-temperature series for the susceptibility {chi} of the square lattice Ising model as well as very long series for the five-particle contribution {chi}{sup (5)} and six-particle contribution {chi}{sup (6)}. These calculations have been made possible by the use of highly optimized polynomial time modular algorithms and a total of more than 150 000 CPU hours on computer clusters. The series for {chi} (low- and high-temperature regimes), {chi}{sup (5)} and {chi}{sup (6)} are now extended to 2000 terms. In addition, for {chi}{sup (5)}, 10 000 terms of the series are calculated modulo a single prime, and have been used to find the linear ODE satisfied by {chi}{sup (5)} modulo a prime. A diff-Pade analysis of the 2000 terms series for {chi}{sup (5)} and {chi}{sup (6)} confirms to a very high degree of confidence previous conjectures about the location and strength of the singularities of the n-particle components of the susceptibility, up to a small set of 'additional' singularities. The exponents at all the singularities of the Fuchsian linear ODE of {chi}{sup (5)} and the (as yet unknown) ODE of {chi}{sup (6)} are given: they are all rational numbers. We find the presence of singularities at w = 1/2 for the linear ODE of {chi}{sup (5)}, and w{sup 2} = 1/8 for the ODE of {chi}{sup (6)}, which are not singularities of the 'physical' {chi}{sup (5)} and {chi}{sup (6)}, that is to say the series solutions of the ODE's which are analytic at w = 0. Furthermore, analysis of the long series for {chi}{sup (5)} (and {chi}{sup (6)}) combined with the corresponding long series for the full susceptibility {chi} yields previously conjectured singularities in some {chi}{sup (n)}, n {>=} 7. The exponents at all these singularities are also seen to be rational numbers. We also present a mechanism of resummation of the logarithmic singularities of the {chi}{sup (n)} leading to the known power-law critical behaviour occurring in

  8. Dynamic spin susceptibility of superconducting cuprates: a microscopic theory of the magnetic resonance mode

    International Nuclear Information System (INIS)

    Vladimirov, A.A.; Plakida, N.M.; Ihle, D.

    2010-01-01

    A microscopic theory of the dynamic spin susceptibility (DSS) in the superconducting state within the t-J model is presented. It is based on an exact representation for the DSS obtained by applying the Mori-type projection technique for the relaxation function in terms of Hubbard operators. The static spin susceptibility is evaluated by a sum-rule-conserving generalized mean-field approximation, while the self-energy is calculated in the mode-coupling approximation. The spectrum of spin excitations is studied in the underdoped and optimally doped regions. The DSS reveals a resonance mode (RM) at the antiferromagnetic wave vector Q=π(1,1) at low temperatures due to a strong suppression of the damping of spin excitations. This is explained by an involvement of spin excitations in the decay process besides the particle-hole continuum usually considered in random-phase-type approximations. The spin gap in the spin-excitation spectrum at Q plays a dominant role in limiting the decay in comparison with the superconducting gap which results in the observation of the RM even above T c in the underdoped region. A good agreement with inelastic neutron-scattering experiments on the RM in YBCO compounds is found

  9. 30 CFR 56.13021 - High-pressure hose connections.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-pressure hose connections. 56.13021... and Boilers § 56.13021 High-pressure hose connections. Except where automatic shutoff valves are used, safety chains or other suitable locking devices shall be used at connections to machines of high-pressure...

  10. 76 FR 38697 - High Pressure Steel Cylinders From China

    Science.gov (United States)

    2011-07-01

    ... imports from China of high pressure steel cylinders, provided for in subheading 7311.00.00 of the... threatened with material injury by reason of LTFV and subsidized imports of high pressure steel cylinders... contained in USITC Publication 4241 (July 2011), entitled High Pressure Steel Cylinders from China...

  11. 77 FR 37712 - High Pressure Steel Cylinders From China

    Science.gov (United States)

    2012-06-22

    ...), that an industry in the United States is materially injured by reason of imports of high pressure steel... preliminary determinations by Commerce that imports of high pressure steel cylinders from China were... Publication 4328 (June 2012), entitled High Pressure Steel Cylinders from China: Investigation Nos. 701-TA-480...

  12. 30 CFR 57.13021 - High-pressure hose connections.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-pressure hose connections. 57.13021... Air and Boilers § 57.13021 High-pressure hose connections. Except where automatic shutoff valves are...-pressure hose lines of 3/4-inch inside diameter or larger, and between high-pressure hose lines of 3/4-inch...

  13. High pressure effect for high-Tc superconductors

    International Nuclear Information System (INIS)

    Takahashi, Hiroki; Tomita, Takahiro

    2011-01-01

    A number of experimental and theoretical studies have been performed to understand the mechanism of high-T c superconductivity and to enhance T c . High-pressure techniques have played a very important role for these studies. In this paper, the high-pressure techniques and physical properties of high-T c superconductor under high pressure are presented. (author)

  14. 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

  15. Subnanosecond breakdown in high-pressure gases

    Science.gov (United States)

    Naidis, George V.; Tarasenko, Victor F.; Babaeva, Natalia Yu; Lomaev, Mikhail I.

    2018-01-01

    Pulsed discharges in high-pressure gases are of considerable interest as sources of nonequilibrium plasma for various technological applications: pollution control, pumping of laser media, plasma-assisted combustion, etc. Recently, attention has been attracted to the use of subnanosecond voltage fronts, producing diffuse discharges with radii of several millimeters. Such plasma structures, similar to pulsed glow discharges, are of special interest for applications due to quasi-uniformity of plasma parameters in relatively large gas volumes. This review presents the results of experimental and computational study of subnanosecond diffuse discharge formation. A description of generators of short high-voltage pulses with subnanosecond fronts and of discharge setups is given. Diagnostic methods for the measurement of various discharge parameters with high temporal and spatial resolution are described. Obtained experimental data on plasma properties for a wide range of governing factors are discussed. A review of various theoretical approaches used for computational study of the dynamics and structure of fast ionization waves is given; the applicability of conventional fluid streamer models for simulation of subnanosecond ionization waves is discussed. Calculated spatial-temporal profiles of plasma parameters during streamer propagation are presented. The efficiency of subnanosecond discharges for the production of reactive species is evaluated. On the basis of the comparison of simulation results and experimental data the effects of various factors (voltage rise time, polarity, etc.) on discharge characteristics are revealed. The major physical phenomena governing the properties of subnanosecond breakdown are analyzed.

  16. Blue emitting organic semiconductors under high pressure

    DEFF Research Database (Denmark)

    Knaapila, Matti; Guha, Suchismita

    2016-01-01

    This review describes essential optical and emerging structural experiments that use high GPa range hydrostatic pressure to probe physical phenomena in blue-emitting organic semiconductors including π-conjugated polyfluorene and related compounds. The work emphasizes molecular structure and inter......This review describes essential optical and emerging structural experiments that use high GPa range hydrostatic pressure to probe physical phenomena in blue-emitting organic semiconductors including π-conjugated polyfluorene and related compounds. The work emphasizes molecular structure...... and intermolecular self-organization that typically determine transport and optical emission in π-conjugated oligomers and polymers. In this context, hydrostatic pressure through diamond anvil cells has proven to be an elegant tool to control structure and interactions without chemical intervention. This has been...... and intermolecular interactions on optical excitations, electron–phonon interaction, and changes in backbone conformations. This picture is connected to the optical high pressure studies of other π-conjugated systems and emerging x-ray scattering experiments from polyfluorenes which provides a structure-property map...

  17. Engineering Model of High Pressure Moist Air

    Directory of Open Access Journals (Sweden)

    Hyhlík Tomáš

    2017-01-01

    Full Text Available The article deals with the moist air equation of state. There are equations of state discussed in the article, i.e. the model of an ideal mixture of ideal gases, the model of an ideal mixture of real gases and the model based on the virial equation of state. The evaluation of sound speed based on the ideal mixture concept is mentioned. The sound speed calculated by the model of an ideal mixture of ideal gases is compared with the sound speed calculated by using the model based on the concept of an ideal mixture of real gases. The comparison of enthalpy end entropy based on the model of an ideal mixture of ideal gases and the model of an ideal mixture of real gases is performed. It is shown that the model of an ideal mixture of real gases deviates from the model of an ideal mixture of ideal gases only in the case of high pressure. An impossibility of the definition of partial pressure in the mixture of real gases is discussed, where the virial equation of state is used.

  18. High Pressure Laminates with Antimicrobial Properties

    Directory of Open Access Journals (Sweden)

    Sandra Magina

    2016-02-01

    Full Text Available High-pressure laminates (HPLs are durable, resistant to environmental effects and good cost-benefit decorative surface composite materials with special properties tailored to meet market demand. In the present work, polyhexamethylene biguanide (PHMB was incorporated for the first time into melamine-formaldehyde resin (MF matrix on the outer layer of HPLs to provide them antimicrobial properties. Chemical binding of PHMB to resin matrix was detected on the surface of produced HPLs by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR. Antimicrobial evaluation tests were carried out on the ensuing HPLs doped with PHMB against gram-positive Listeria innocua and gram-negative Escherichia coli bacteria. The results revealed that laminates prepared with 1.0 wt % PHMB in MF resin were bacteriostatic (i.e., inhibited the growth of microorganisms, whereas those prepared with 2.4 wt % PHMB in MF resin exhibited bactericidal activity (i.e., inactivated the inoculated microorganisms. The results herein reported disclose a promising strategy for the production of HPLs with antimicrobial activity without affecting basic intrinsic quality parameters of composite material.

  19. High pressure phase transitions in Europous oxide

    International Nuclear Information System (INIS)

    Kremser, D.T.

    1982-01-01

    The pressure-volume relationship for EuO was investigated to 630 kilobars at room temperature with a diamond-anvil, high-pressure cell. Volumes were determined by x-ray diffraction; pressures were determined by the ruby R 1 fluorescence method. The preferred interpretation involves normal compression behavior for EuO, initially in the B1 (NaCl-type) structure, to about 280 kilobars. Between approx. =280 and approx. =350 kilobars a region of anomalous compressibility in which the volume drops continuously by approximately 2% is observed. A second-order electronic transition is proposed with the 6s band overlapping with the 4f levels, thereby reducing the volume of EuO without changing the structure. This is not a semiconductor-to-metal transition. In reflected light, this transition is correlated with a subtle and continuous change in color from brown-black to a light brown. The collapsed B1 phase (postelectronic transition) is stable between approx. =350 and approx. =400 kilobars. At about 400 kilobars the collapsed B1 structure transforms to the B2 (CsCl-type) structure, with a zero pressure-volume change of approximately 12 +/- 1.5%

  20. Electrical resistance and magnetoresistance of UCoAl under high pressure

    Czech Academy of Sciences Publication Activity Database

    Honda, F.; Oomi, G.; Andreev, Alexander V.; Sechovský, V.; Shiokawa, Y.

    --, - (2002), s. 126-128 ISSN 0022-3131 R&D Projects: GA ČR GP202/01/D045 Institutional research plan: CEZ:AV0Z1010914 Keywords : UCoAl * non-Fermi liquid * itinerant metamagnetism * electrical resistance * high pressure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.572, year: 2002

  1. Purification Efficacy of Synthetic Cannabinoid Conjugates Using High-Pressure Liquid Chromatography

    Science.gov (United States)

    conducted using high-pressure liquid chromatography and gradient screens to determine the most effective means of purifying the SC:dark quencher conjugates...to obtain the highest yields and purity. The purity was verified using liquid chromatographycoupled mass spectroscopy and nuclear magnetic resonance.

  2. Recent progress in high-pressure studies on organic conductors

    Directory of Open Access Journals (Sweden)

    Syuma Yasuzuka and Keizo Murata

    2009-01-01

    Full Text Available Recent high-pressure studies of organic conductors and superconductors are reviewed. The discovery of the highest Tc superconductivity among organics under high pressure has triggered the further progress of the high-pressure research. Owing to this finding, various organic conductors with the strong electron correlation were investigated under high pressures. This review includes the pressure techniques using the cubic anvil apparatus, as well as high-pressure studies of the organic conductors up to 10 GPa showing extraordinary temperature and pressure dependent transport phenomena.

  3. Development of high pressure pipe scanners

    International Nuclear Information System (INIS)

    Kim, Jae H.; Lee, Jae C.; Moon, Soon S.; Eom, Heung S.; Choi, Yu R.

    1998-12-01

    This report describes an automatic ultrasonic scanning system for pressure pipe welds, which was developed in this project using recent advanced technologies on mobile robot and computer. The system consists of two modules: a robot scanner module which navigates and manipulates scanning devices, and a data acquisition module which generates ultrasonic signal and processes the data from the scanner. The robot has 4 magnetic wheels and 2 -axis manipulator on which ultrasonic transducer attached. The wheeled robot can navigate curved surface such as outer wall of circular pipes. Magnetic wheels were optimally designed through magnetic field analysis. Free surface sensing and line tracking control algorithm were developed and implemented, and the control devices and software can be used in practical inspection works. We expect our system can contribute to reduction of inspection time, performance enhancement, and effective management of inspection results

  4. 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.

  5. Pressure Dome for High-Pressure Electrolyzer

    Science.gov (United States)

    Norman, Timothy; Schmitt, Edwin

    2012-01-01

    A high-strength, low-weight pressure vessel dome was designed specifically to house a high-pressure [2,000 psi (approx. = 13.8 MPa)] electrolyzer. In operation, the dome is filled with an inert gas pressurized to roughly 100 psi (approx. = 690 kPa) above the high, balanced pressure product oxygen and hydrogen gas streams. The inert gas acts to reduce the clamping load on electrolyzer stack tie bolts since the dome pressure acting axially inward helps offset the outward axial forces from the stack gas pressure. Likewise, radial and circumferential stresses on electrolyzer frames are minimized. Because the dome is operated at a higher pressure than the electrolyzer product gas, any external electrolyzer leak prevents oxygen or hydrogen from leaking into the dome. Instead the affected stack gas stream pressure rises detectably, thereby enabling a system shutdown. All electrical and fluid connections to the stack are made inside the pressure dome and require special plumbing and electrical dome interfaces for this to be accomplished. Further benefits of the dome are that it can act as a containment shield in the unlikely event of a catastrophic failure. Studies indicate that, for a given active area (and hence, cell ID), frame outside diameter must become ever larger to support stresses at higher operating pressures. This can lead to a large footprint and increased costs associated with thicker and/or larger diameter end-plates, tie-rods, and the frames themselves. One solution is to employ rings that fit snugly around the frame. This complicates stack assembly and is sometimes difficult to achieve in practice, as its success is strongly dependent on frame and ring tolerances, gas pressure, and operating temperature. A pressure dome permits an otherwise low-pressure stack to operate at higher pressures without growing the electrolyzer hardware. The pressure dome consists of two machined segments. An O-ring is placed in an O-ring groove in the flange of the bottom

  6. Cobalt ferrite nanoparticles under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Saccone, F. D.; Ferrari, S.; Grinblat, F.; Bilovol, V. [Instituto de Tecnologías y Ciencias de la Ingeniería, “Ing. H. Fernández Long,” Av. Paseo Colón 850 (1063), Buenos Aires (Argentina); Errandonea, D., E-mail: daniel.errandonea@uv.es [Departamento de Fisica Aplicada, Institut Universitari de Ciència dels Materials, Universitat de Valencia, c/ Doctor Moliner 50, E-46100 Burjassot, Valencia (Spain); Agouram, S. [Departamento de Física Aplicada y Electromagnetismo, Universitat de València, 46100 Burjassot, Valencia (Spain)

    2015-08-21

    We report by the first time a high pressure X-ray diffraction and Raman spectroscopy study of cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles carried out at room temperature up to 17 GPa. In contrast with previous studies of nanoparticles, which proposed the transition pressure to be reduced from 20–27 GPa to 7.5–12.5 GPa (depending on particle size), we found that cobalt ferrite nanoparticles remain in the spinel structure up to the highest pressure covered by our experiments. In addition, we report the pressure dependence of the unit-cell parameter and Raman modes of the studied sample. We found that under quasi-hydrostatic conditions, the bulk modulus of the nanoparticles (B{sub 0} = 204 GPa) is considerably larger than the value previously reported for bulk CoFe{sub 2}O{sub 4} (B{sub 0} = 172 GPa). In addition, when the pressure medium becomes non-hydrostatic and deviatoric stresses affect the experiments, there is a noticeable decrease of the compressibility of the studied sample (B{sub 0} = 284 GPa). After decompression, the cobalt ferrite lattice parameter does not revert to its initial value, evidencing a unit cell contraction after pressure was removed. Finally, Raman spectroscopy provides information on the pressure dependence of all Raman-active modes and evidences that cation inversion is enhanced by pressure under non-hydrostatic conditions, being this effect not fully reversible.

  7. 87Sr/86Sr dating and preliminary interpretation of magnetic susceptibility logs of giant piston cores from the Rio Grande Rise in the South Atlantic

    Science.gov (United States)

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

    2017-12-01

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

  8. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1975-01-01

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

  10. 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.

  11. 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

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

    Science.gov (United States)

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

    2014-04-01

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

  13. Behavior of the dynamic magnetic susceptibility in ybco bula ceramics irradiated with gamma rays

    International Nuclear Information System (INIS)

    Leyva Fabelo, A.; Bouza Dominguez, J.; Cruz Inclan, Carlos M.

    2001-01-01

    Using measurements of the ac susceptibility, the behavior with the irradiation dose of YBa2Cu3O7- bulk ceramics synthesized by the classic reaction method in solid state, was studied. A Co60 gamma chamber model MPX-G-25M and a Cs137 source were employed as gamma ray sources. The behavior of the beginning temperature of the normal - superconducting state transition with the exposition dose show, independently of the incident gamma energy, a monotonous growth until reaching a threshold dose, after which, observe a fall, more abrupt in the case of the Co60. This behavior can be explained using the model that postulates the ability of the gamma radiation, in certain dose intervals, to stimulate the structural reordering in the oxygen sublattice. When the irradiation process takes place in the Co60 gamma chamber, the behavior of the superconducting volume fraction of the sample characterizes by the initial sharp fall with the dose, followed with an attenuation of the decrement. In the case of Cs137 irradiation, the behavior of the superconducting volume fraction is similar to the behavior of the Ton with the dose

  14. 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

  15. Neutron powder diffraction under high pressure at J-PARC

    International Nuclear Information System (INIS)

    Utsumi, Wataru; Kagi, Hiroyuki; Komatsu, Kazuki; Arima, Hiroshi; Nagai, Takaya; Okuchi, Takuo; Kamiyama, Takashi; Uwatoko, Yoshiya; Matsubayashi, Kazuyuki; Yagi, Takehiko

    2009-01-01

    It is expected that high-pressure material science and the investigation of the Earth's interior will progress greatly using the high-flux pulse neutrons of J-PARC. In this article, we introduce our plans for in situ neutron powder diffraction experiments under high pressure at J-PARC. The use of three different types of high-pressure devices is planned; a Paris-Edinburgh cell, a new opposed-anvil cell with a nano-polycrystalline diamond, and a cubic anvil high-pressure apparatus. These devices will be brought to the neutron powder diffraction beamlines to conduct a 'day-one' high-pressure experiment. For the next stage of research, we propose construction of a dedicated beamline for high-pressure material science. Its conceptual designs are also introduced here.

  16. Safety regulation on high-pressure gas and gas business

    International Nuclear Information System (INIS)

    Kim, Du Yeoung; An, Dae Jun

    1978-09-01

    This book is divided into two parts. The first part introduces safety regulation on high-pressure gas, enforcement ordinance on safety regulation about high-pressure gas and enforcement regulation on safety regulation about high-pressure gas. The second part indicates regulations on gas business such as general rules, gas business gas supplies, using land, supervision, supple mentary rules and penalty. It has two appendixes on expected questions and questions during last years.

  17. 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.

  18. Strongly correlated electrons at high pressure: an approach by inelastic X-Ray scattering

    International Nuclear Information System (INIS)

    Rueff, J.P.

    2007-06-01

    Inelastic X-ray scattering (IXS) and associated methods has turn out to be a powerful alternative for high-pressure physics. It is an all-photon technique fully compatible with high-pressure environments and applicable to a vast range of materials. Standard focalization of X-ray in the range of 100 microns is typical of the sample size in the pressure cell. Our main aim is to provide an overview of experimental results obtained by IXS under high pressure in 2 classes of materials which have been at the origin of the renewal of condensed matter physics: strongly correlated transition metal oxides and rare-earth compounds. Under pressure, d and f-electron materials show behaviors far more complex that what would be expected from a simplistic band picture of electron delocalization. These spectroscopic studies have revealed unusual phenomena in the electronic degrees of freedom, brought up by the increased density, the changes in the charge-carrier concentration, the over-lapping between orbitals, and hybridization under high pressure conditions. Particularly we discuss about pressure induced magnetic collapse and metal-insulator transitions in 3d compounds and valence fluctuations phenomena in 4f and 5f compounds. Thanks to its superior penetration depth, chemical selectivity and resonant enhancement, resonant inelastic X-ray scattering has appeared extremely well suited to high pressure physics in strongly correlated materials. (A.C.)

  19. Paleocurrents of the Middle-Upper Jurassic strata in the Paradox Basin, Colorado, inferred from anisotropy of magnetic susceptibility (AMS)

    Science.gov (United States)

    Ejembi, J. I.; Ferre, E. C.; Potter-McIntyre, S. L.

    2017-12-01

    The Middle-Upper Jurassic sedimentary strata in the southwestern Colorado Plateau recorded pervasive eolian to fluvio-lacustrine deposition in the Paradox Basin. While paleocurrents preserved in the Entrada Sandstone, an eolian deposition in the Middle Jurassic, has been well constrained and show a northwesterly to northeasterly migration of ergs from the south onto the Colorado Plateau, there is yet no clear resolution of the paleocurrents preserved in the Wanakah Formation and Tidwell Member of the Morrison Formation, both of which are important sedimentary sequences in the paleogeographic framework of the Colorado Plateau. New U-Pb detrital zircon geochronology of sandstones from these sequences suggests that an abrupt change in provenance occurred in the early Late Jurassic, with sediments largely sourced from eroding highlands in central Colorado. We measured the anisotropy of magnetic susceptibility (AMS) of sediments in oriented sandstone samples from these three successive sequences; first, to determine the paleocurrents from the orientations of the AMS fabrics in order to delineate the source area and sediments dispersal pattern and second, to determine the depositional mechanisms of the sediments. Preliminary AMS data from two study sites show consistency and clustering of the AMS axes in all the sedimentary sequences. The orientations of the Kmin - Kint planes in the Entrada Sandstone sample point to a NNE-NNW paleocurrent directions, which is in agreement with earlier studies. The orientations of the Kmin - Kint planes in the Wanakah Formation and Tidwell Member samples show W-SW trending paleocurrent directions, corroborating our hypothesis of a shift in provenance to the eroding Ancestral Front Range Mountain, located northeast of the Paradox Basin, during the Late Jurassic. Isothermal remanence magnetization (IRM) of the samples indicate that the primary AMS carriers are detrital, syndepositional ferromagnetic minerals. Thus, we contend that AMS can

  20. The compact mirrors with high pressure plasmas

    International Nuclear Information System (INIS)

    Anikeev, A.V.; Bagryansky, P.A.; Ivanov, A.A.; Lizunov, A.A.; Murakhtin, S.V.; Prikhodko, V.V.; Collatz, S.; Noack, K.

    2004-01-01

    The gas dynamic trap (GDP) experimental facility at the Budker Institute Novosibirsk is a long axial-symmetric mirror system with a high mirror ratio variable in the range of 12.5 - 100 for the confinement of a two-component plasma. One component is a collisional plasma with ion and electron temperatures up to 100 eV and density up to 10 14 cm -3 . The second component is the population of high-energetic fast ions with energies of 2-18 keV and a density up to 10 13 cm -3 which is produced by neutral beam injection (NBI). GDP is currently undergoing an upgrade whose first stage is the achievement of the synthesized hot ion plasmoid experiment (SHIP). This experiment aims at the investigation of plasmas and at the knowledge of plasma parameters that have never been achieved before in magnetic mirrors. The paper presents the physical concept of the SHIP experiment, the results of numerical pre-calculations and draws conclusions regarding possible scenarios of experiments. The simulation of a maximal NBI power regime with hydrogen injection gave a fast ion density of 1.2*10 14 cm -3 with a mean energy of 14 keV. The calculation of the deuterium injection regime with 2 MW NBI power gave a maximal fast ion density of 1.9*10 14 cm -3 with a beam energy of 9 keV. The calculation of an experimental scenario with reduced magnetic field resulted in a maximal β-value of 62%, so this regime is recommended for the study of high-β effects in plasmas confined in axial-symmetric mirrors

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

    Science.gov (United States)

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

    2017-10-01

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

  2. 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.

  3. Magnetic susceptibility of Variscan granite-types of the Spanish Central System and the redox state of magma

    Energy Technology Data Exchange (ETDEWEB)

    Villaseca, C.; Ruiz-Martínez, V.C.; Pérez-Soba, C.

    2017-07-01

    Magnetic susceptibility (MS) has been measured in Variscan granites from central Spain. They yield values in the order of 15 to 180μSI units for S- and I-type granites, indicating that both types belong to the ilmenite series. Only samples from magnetite-bearing leucogranites from the I-type La Pedriza massif show high MS values, in the order of 500-1400μSI, reflecting the presence of this ferromagnetic mineral. Mineral chemistry of magmatic Fe-rich minerals (mainly biotite) suggests similar oxidation values for both granite types. MS values change in highly fractionated granites accordingly either with the presence of rare new Fe-oxide phases (some I-type leucogranites) or with the marked modal amount decrease of Fe-rich minerals (I- and S-type leucogranites). The redox state in highly fractionated granite melts is mostly controlled by magmatic processes that modify redox conditions inherited from the source region. Thus, the occurrence of magnetite or ilmenite in granites is primarily controlled by the oxidation state of the source material but also by the differentiation degree of the granite melt. The presence of magnetite in some Variscan I-type leucogranites might be a consequence of crystal fractionation processes in a more limited mafic mineral assemblage than in S-type granite melts.

  4. Magnetic Resonance Imaging Susceptibility-Weighted Imaging Lesion and Contrast Enhancement May Represent Infectious Intracranial Aneurysm in Infective Endocarditis.

    Science.gov (United States)

    Cho, Sung-Min; Rice, Cory; Marquardt, Robert J; Zhang, Lucy Q; Khoury, Jean; Thatikunta, Prateek; Buletko, Andrew B; Hardman, Julian; Uchino, Ken; Wisco, Dolora

    2017-01-01

    Infectious intracranial aneurysm (IIA) can complicate infective endocarditis (IE). We aimed to describe the magnetic resonance imaging (MRI) characteristics of IIA. We reviewed IIAs among 116 consecutive patients with active IE by conducting a neurological evaluation at a single tertiary referral center from January 2015 to July 2016. MRIs and digital cerebral angiograms (DSA) were reviewed to identify MRI characteristics of IIAs. MRI susceptibility weighted imaging (SWI) was performed to collect data on cerebral microbleeds (CMBs) and sulcal SWI lesions. Out of 116 persons, 74 (63.8%) underwent DSA. IIAs were identified in 13 (17.6% of DSA, 11.2% of entire cohort) and 10 patients with aneurysms underwent MRI with SWI sequence. Nine (90%) out of 10 persons with IIAs had CMB >5 mm or sulcal lesions in SWI (9 in sulci, 6 in parenchyma, and 5 in both). Five out of 8 persons who underwent MRI brain with contrast had enhancement within the SWI lesions. In a multivariate logistic regression analysis, both sulcal SWI lesions (p < 0.001, OR 69, 95% CI 7.8-610) and contrast enhancement (p = 0.007, OR 16.5, 95% CI 2.3-121) were found to be significant predictors of the presence of IIAs. In the individuals with IE who underwent DSA and MRI, we found that neuroimaging characteristics, such as sulcal SWI lesion with or without contrast enhancement, are associated with the presence of IIA. © 2017 S. Karger AG, Basel.

  5. Advances in high pressure science and technology: proceedings of the fourth national conference on high pressure science and technology

    International Nuclear Information System (INIS)

    Yousuf, Mohammad; Subramanian, N.; Govinda Rajan, K.

    1997-09-01

    The proceedings of the fourth National Conference on High Pressure Science and Technology covers a wide area of research and development activities in the field of high pressure science and technology, broadly classified into the following themes: mechanical behaviour of materials; instrumentation and methods in high pressure research; pressure calibration, standards and safety aspects; phase transitions; shock induced reactions; mineral science, geophysics, geochemistry and planetary sciences; optical, electronic and transport properties; synthesis of materials; soft condensed matter physics and liquid crystals; computational methods in high pressure research. Papers relevant to INIS are indexed separately

  6. 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.

  7. High-pressure Moessbauer study of perovskite iron oxides

    CERN Document Server

    Kawakami, T; Sasaki, T; Kuzushita, K; Morimoto, S; Endo, S; Kawasaki, S; Takano, M

    2002-01-01

    The perovskite oxides CaFeO sub 3 and La sub 1 sub / sub 3 Sr sub 2 sub / sub 3 FeO sub 3 have been investigated by high-pressure sup 5 sup 7 Fe Moessbauer spectroscopy. The critical temperatures of the charge disproportionation (CD) and the magnetic order (MO) have been determined as a function of pressure. In CaFeO sub 3 the CD (2Fe sup 4 sup + -> Fe sup 3 sup + + Fe sup 5 sup +) occurs at an almost constant temperature of 290 K in the pressure range of 0-17 GPa. Above 20 GPa, the CD is suppressed. The MO temperature of 125 K at an ambient pressure rises to 300 K at 34 GPa. In La sub 1 sub / sub 3 Sr sub 2 sub / sub 3 FeO sub 3 the CD (3Fe sup 1 sup 1 sup / sup 3 sup + -> 2Fe sup 3 sup + + Fe sup 5 sup +) and the MO occur at the same temperature up to 21 GPa, which decreases from 207 to 165 K with increasing pressure. Above 25 GPa, however, the MO temperature rises above 400 K.

  8. High pressure die casting of Fe-based metallic glass

    Science.gov (United States)

    Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

    2016-01-01

    Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications. PMID:27725780

  9. Superconductivity of ternary metal compounds prepared at high pressures

    CERN Document Server

    Shirotani, I

    2003-01-01

    Various ternary metal phosphides, arsenides, antimonides, silicides and germanides have been prepared at high temperatures and high pressures. These ternary metal compounds can be classified into four groups: [1] metal-rich compounds MM' sub 4 X sub 2 and [2] MM'X, [3] non-metal-rich compounds MXX' and [4] MM' sub 4 X sub 1 sub 2 (M and M' = metal element; X and X' = non-metal element). We have studied the electrical and magnetic properties of these materials at low temperatures, and found many new superconductors with the superconducting transition temperature (T sub c) of above 10 K. The metal-rich compound ZrRu sub 4 P sub 2 with a tetragonal structure showed the superconducting transition at around 11 K, and had an upper critical field (H sub c sub 2) of 12.2 tesla (T) at 0 K. Ternary equiatomic compounds ZrRuP and ZrRuSi crystallize in two modifications, a hexagonal Fe sub 2 P-type structure [h-ZrRuP(Si)] and an orthorhombic Co sub 2 P-type structure [o-ZrRuP(Si)]. Both h-ZrRuP and h-ZrRuSi have rather h...

  10. High pressure die casting of Fe-based metallic glass.

    Science.gov (United States)

    Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

    2016-10-11

    Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications.

  11. High pressure die casting of Fe-based metallic glass

    Science.gov (United States)

    Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

    2016-10-01

    Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications.

  12. 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

  13. High-Pressure Oxygen Generation for Outpost EVA Study

    Science.gov (United States)

    Jeng, Frank F.; Conger, Bruce; Ewert, Michael K.; Anderson, Molly S.

    2009-01-01

    The amount of oxygen consumption for crew extravehicular activity (EVA) in future lunar exploration missions will be significant. Eight technologies to provide high pressure EVA O2 were investigated. They are: high pressure O2 storage, liquid oxygen (LOX) storage followed by vaporization, scavenging LOX from Lander followed by vaporization, LOX delivery followed by sorption compression, water electrolysis followed by compression, stand-alone high pressure water electrolyzer, Environmental Control and Life Support System (ECLSS) and Power Elements sharing a high pressure water electrolyzer, and ECLSS and In-Situ Resource Utilization (ISRU) Elements sharing a high pressure electrolyzer. A trade analysis was conducted comparing launch mass and equivalent system mass (ESM) of the eight technologies in open and closed ECLSS architectures. Technologies considered appropriate for the two architectures were selected and suggested for development.

  14. 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

  15. High pressure Moessbauer spectroscopy with nuclear resonant forward scattering of synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Nasu, Saburo [Osaka Univ., Toyonaka (Japan). Faculty of Engineering Science

    1996-04-01

    The first observation of the pressure-induced transition from the antiferromagnetic to the ferromagnetic SrFeO{sub 3} was succeeded by measuring Moessbauer spectroscopy under high pressure produced by the diamond anvil cell (DAC). Sample is a polycrystal powder of antiferromagnetic SrFe0{sub 3} with the Neel temperature T{sub N}=140 K, the cubic system and perovskite type crystal. The average pressures used were 44 GPa and 74 GPa (300 K). SrFeO{sub 3} is paramagnetic material at 300 K, but the Neel temperature increases more than 300 K under high pressure and the quantized axis turns to the external magnetic field, so that we take it as it means the system displaying the phase transition to the ferromagnet. By the method, we can practice the measurement at low and high temperature under the external magnetic field by using the polarized light source. (S.Y.)

  16. 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

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

    International Nuclear Information System (INIS)

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

    1975-01-01

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

  18. High-pressure effects on isotropic superconductivity in the iron-free layered pnictide superconductor BaPd2As2

    Science.gov (United States)

    Abdel-Hafiez, M.; Zhao, Y.; Huang, Z.; Cho, C.-w.; Wong, C. H.; Hassen, A.; Ohkuma, M.; Fang, Y.-W.; Pan, B.-J.; Ren, Z.-A.; Sadakov, A.; Usoltsev, A.; Pudalov, V.; Mito, M.; Lortz, R.; Krellner, C.; Yang, W.

    2018-04-01

    While the layered 122 iron arsenide superconductors are highly anisotropic, unconventional, and exhibit several forms of electronic orders that coexist or compete with superconductivity in different regions of their phase diagrams, we find in the absence of iron in the structure that the superconducting characteristics of the end member BaPd2As2 are surprisingly conventional. Here we report on complementary measurements of specific heat, magnetic susceptibility, resistivity measurements, Andreev spectroscopy, and synchrotron high pressure x-ray diffraction measurements supplemented with theoretical calculations for BaPd2As2 . Its superconducting properties are completely isotropic as demonstrated by the critical fields, which do not depend on the direction of the applied field. Under the application of high pressure, Tc is linearly suppressed, which is the typical behavior of classical phonon-mediated superconductors with some additional effect of a pressure-induced decrease in the electronic density of states and the electron-phonon coupling parameters. Structural changes in the layered BaPd2As2 have been studied by means of angle-dispersive diffraction in a diamond-anvil cell. At 12 GPa and 24.2 GPa we observed pressure induced lattice distortions manifesting as the discontinuity and, hence discontinuity in the Birch-Murnaghan equation of state. The bulk modulus is B0=40 (6 ) GPa below 12 GPa and B0=142 (3 ) GPa below 27.2 GPa.

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

    International Nuclear Information System (INIS)

    Matsuura, Hideki

    2002-01-01

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

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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