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Sample records for chemistry conductivity magnetism

  1. Conductive Polymer Functionalization by Click Chemistry

    Daugaard, Anders Egede; Hvilsted, Søren; Hansen, Thomas Steen

    2008-01-01

    Click chemistry is used to obtain new conductive polymer films based on poly(3,4-ethylenedioxythiophene) (PEDOT) from a new azide functional monomer. Postpolymerization, 1,3-dipolar cycloadditions in DMF, using a catalyst system of CUS04 and sodium ascorbate, and different alkynes are performed...

  2. Smart Surface Chemistries of Conducting Polymers

    Lind, Johan Ulrik

    In this thesis we investigate post-polymerization covalent modifications of poly(3,4-dioxythiophene (PEDOT)-type conducting polymers. The aim of the modifications is to gain specific control of the interaction between the material and living mammalian cells. The use of “click-chemistry” to modify...... a straightforward and in-expensive method for patterning conducting polymer thin films into microelectrodes, without losing control of the surface chemistry of the samples. On the contrary, the method provides direct control of the surface chemistry of both the fabricated micro-electrodes and the gaps between them....... The method is based on locally removing PEDOTtype polymers to expose underlying non-conducting functional polymer substrates. Thereby, multifunctional substrates are obtained. By applying this method, we are able to fabricate allpolymer micro-systems with multiple types of localized functional (bio...

  3. Magnetic resonance imaging of chemistry.

    Britton, Melanie M

    2010-11-01

    Magnetic resonance imaging (MRI) has long been recognized as one of the most important tools in medical diagnosis and research. However, MRI is also well placed to image chemical reactions and processes, determine the concentration of chemical species, and look at how chemistry couples with environmental factors, such as flow and heterogeneous media. This tutorial review will explain how magnetic resonance imaging works, reviewing its application in chemistry and its ability to directly visualise chemical processes. It will give information on what resolution and contrast are possible, and what chemical and physical parameters can be measured. It will provide examples of the use of MRI to study chemical systems, its application in chemical engineering and the identification of contrast agents for non-clinical applications. A number of studies are presented including investigation of chemical conversion and selectivity in fixed-bed reactors, temperature probes for catalyst pellets, ion mobility during tablet dissolution, solvent dynamics and ion transport in Nafion polymers and the formation of chemical waves and patterns.

  4. The Organic Chemistry of Conducting Polymers

    Tolbert, Laren Malcolm [Georgia Inst. of Technology, Atlanta, GA (United States)

    2014-12-01

    For the last several years, we have examined the fundamental principles of conduction in one-dimensional systems, i.e., molecular “wires”. It is, of course, widely recognized that such systems, as components of electronically conductive materials, function in a two- and three-dimensional milieu. Thus interchain hopping and grain-boundary resistivity are limiting conductivity factors in highly conductive materials, and overall conductivity is a function of through-chain and boundary hopping. We have given considerable attention to the basic principles underlying charge transport (the “rules of the game”) in two-dimensional systems by using model systems which allow direct observation of such processes, including the examination of tunneling and hopping as components of charge transfer. In related work, we have spent considerable effort on the chemistry of conjugated heteropolymers, most especially polythiophens, with the aim of using these most efficient of readily available electroactive polymers in photovoltaic devices.

  5. Spatially Selective Functionalization of Conducting Polymers by "Electroclick" Chemistry

    Hansen, Thomas Steen; Daugaard, Anders Egede; Hvilsted, Søren

    2009-01-01

    Conducting polymer microelectrodes can electrochemically generate the catalyst required for their own functionalization by "click chemistry" with high spatial resolution. Interdigitated microelectrodes prepared from an azide-containing conducting polymer are selectively functionalized in sequence...

  6. Hall conductivity for two dimensional magnetic systems

    Desbois, J.; Ouvry, S.; Texier, C.

    1996-01-01

    A Kubo inspired formalism is proposed to compute the longitudinal and transverse dynamical conductivities of an electron in a plane (or a gas of electrons at zero temperature) coupled to the potential vector of an external local magnetic field, with the additional coupling of the spin degree of freedom of the electron to the local magnetic field (Pauli Hamiltonian). As an example, the homogeneous magnetic field Hall conductivity is rederived. The case of the vortex at the origin is worked out in detail. A perturbative analysis is proposed for the conductivity in the random magnetic impurity problem (Poissonian vortices in the plane). (author)

  7. Electrical conductivity of conductive carbon blacks: influence of surface chemistry and topology

    Pantea, Dana; Darmstadt, Hans; Kaliaguine, Serge; Roy, Christian

    2003-01-01

    Conductive carbon blacks from different manufacturers were studied in order to obtain some insight into the relation between their electrical conductivity and their surface properties. The surface chemistry was studied by X-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectroscopy (SIMS), whereas the topology of the carbon black surface was investigated using low-pressure nitrogen adsorption. All these techniques yield information on the graphitic character of the surface. In general, the electrical conductivity of the conductive blacks increases with the graphitic character of the surface. For low surface area conductive blacks, the electrical conductivity correlates well with the surface chemistry. In the case of the XPS and SIMS data, this correlation is also valid when other types of carbon blacks such as thermal and furnace blacks are included, confirming the determining influence of the carbon black surface chemistry on the electrical conductivity

  8. Microwave assisted click chemistry on a conductive polymer film

    Daugaard, Anders Egede; Hansen, Thomas S.; Larsen, Niels Bent

    2011-01-01

    Microwave (MW) irradiation has been used to accelerate the functionalization of an azide functional poly(3,4-ethylenedioxythiophene) film by click chemistry. The absorption of MW energy by the conductive polymer has been exploited for localized activation of the reaction on the polymer surface...

  9. Conducting single-molecule magnet materials.

    Cosquer, Goulven; Shen, Yongbing; Almeida, Manuel; Yamashita, Masahiro

    2018-05-11

    Multifunctional molecular materials exhibiting electrical conductivity and single-molecule magnet (SMM) behaviour are particularly attractive for electronic devices and related applications owing to the interaction between electronic conduction and magnetization of unimolecular units. The preparation of such materials remains a challenge that has been pursued by a bi-component approach of combination of SMM cationic (or anionic) units with conducting networks made of partially oxidized (or reduced) donor (or acceptor) molecules. The present status of the research concerning the preparation of molecular materials exhibiting SMM behaviour and electrical conductivity is reviewed, describing the few molecular compounds where both SMM properties and electrical conductivity have been observed. The evolution of this research field through the years is discussed. The first reported compounds are semiconductors in spite being able to present relatively high electrical conductivity, and the SMM behaviour is observed at low temperatures where the electrical conductivity of the materials is similar to that of an insulator. During the recent years, a breakthrough has been achieved with the coexistence of high electrical conductivity and SMM behaviour in a molecular compound at the same temperature range, but so far without evidence of a synergy between these properties. The combination of high electrical conductivity with SMM behaviour requires not only SMM units but also the regular and as far as possible uniform packing of partially oxidized molecules, which are able to provide a conducting network.

  10. Conductance of auroral magnetic field lines

    Weimer, D.R.; Gurnett, D.A.; Goertz, C.K.

    1986-01-01

    DE-1 high-resolution double-probe electric-field data and simultaneous magnetic-field measurements are reported for two 1981 events with large electric fields which reversed over short distances. The data are presented graphically and analyzed in detail. A field-line conductance of about 1 nmho/sq m is determined for both upward and downward currents, and the ionospheric conductivity is shown, in the short-wavelength limit, to have little effect on the relationship between the (N-S) electric and (E-W) magnetic fields above the potential drop parallel to the magnetic-field lines. The results are found to be consistent with a linear relationship between the field-aligned current density and the parallel potential drop. 14 references

  11. Magnetic anisotropy and anisotropic ballistic conductance of thin magnetic wires

    Sabirianov, R.

    2006-01-01

    The magnetocrystalline anisotropy of thin magnetic wires of iron and cobalt is quite different from the bulk phases. The spin moment of monatomic Fe wire may be as high as 3.4 μ B , while the orbital moment as high as 0.5 μ B . The magnetocrystalline anisotropy energy (MAE) was calculated for wires up to 0.6 nm in diameter starting from monatomic wire and adding consecutive shells for thicker wires. I observe that Fe wires exhibit the change sign with the stress applied along the wire. It means that easy axis may change from the direction along the wire to perpendicular to the wire. We find that ballistic conductance of the wire depends on the direction of the applied magnetic field, i.e. shows anisotropic ballistic magnetoresistance. This effect occurs due to the symmetry dependence of the splitting of degenerate bands in the applied field which changes the number of bands crossing the Fermi level. We find that the ballistic conductance changes with applied stress. Even for thicker wires the ballistic conductance changes by factor 2 on moderate tensile stain in our 5x4 model wire. Thus, the ballistic conductance of magnetic wires changes in the applied field due to the magnetostriction. This effect can be observed as large anisotropic BMR in the experiment

  12. Suspension chemistry and electrophoretic deposition of zirconia electrolyte on conducting and non-conducting substrates

    Das, Debasish; Basu, Rajendra N.

    2013-01-01

    Graphical abstract: - Highlights: • Stable suspension of yttria stabilized zirconia (YSZ) obtained in isopropanol medium. • Suspension chemistry and process parameters for electrophoretic deposition optimized. • Deposited film quality changed with iodine and water (dispersants) concentration. • Dense YSZ film (∼5 μm) fabricated onto non-conducting porous NiO-YSZ anode substrate. - Abstract: Suspensions of 8 mol% yttria stabilized zirconia (YSZ) particulates in isopropanol medium are prepared using acetylacetone, iodine and water as dispersants. The effect of dispersants concentration on suspension stability, particle size distribution, electrical conductivity and pH of the suspensions are studied in detail to optimize the suspension chemistry. Electrophoretic deposition (EPD) has been conducted to produce thin and dense YSZ electrolyte films. Deposition kinetics have been studied in depth and good quality films on conducting substrate are obtained at an applied voltage of 15 V for 3 min. YSZ films are also fabricated on non-conducting NiO-YSZ anode substrate using a steel plate on the reverse side of the substrate. Upon co-firing at 1400 °C for 6 h a dense YSZ film of thickness ∼5 μm is obtained. Such a half cell (anode + electrolyte) can be used to fabricate a solid oxide fuel cell on applying a suitable cathode layer

  13. Magnetic impurity coupled to interacting conduction electrons

    Schork, T.

    1996-01-01

    We consider a magnetic impurity which interacts by hybridization with a system of weakly correlated electrons and determine the energy of the ground state by means of a 1/N f expansion. The correlations among the conduction electrons are described by a Hubbard Hamiltonian and are treated to the lowest order in the interaction strength. We find that their effect on the Kondo temperature, T K , in the Kondo limit is twofold: first, the position of the impurity level is shifted due to the reduction of charge fluctuations, which reduces T K . Secondly, the bare Kondo exchange coupling is enhanced as spin fluctuations are enlarged. In total, T K increases. Both corrections require intermediate states beyond the standard Varma-Yafet ansatz. This shows that the Hubbard interaction does not just provide quasiparticles, which hybridize with the impurity, but also renormalizes the Kondo coupling. copyright 1996 The American Physical Society

  14. Magnetic relaxation in analytical, coordination and bioinorganic chemistry

    Mikhajlov, O.

    1982-01-01

    Nuclear magnetic relaxation is a special type of nuclear magnetic resonance in which the rate is measured of energy transfer between the excited nuclei and their molecular medium (spin-lattice relaxation) or the whole nuclear spin system (spin-spin relaxation). Nuclear magnetic relaxation relates to nuclei with a spin of 1/2, primarily H 1 1 , and is mainly measured in water solutions. It is suitable for (1) analytical chemistry because the relaxation time rapidly reduces in the presence of paramagnetic ions, (2) the study of complex compounds, (3) the study of biochemical reactions in the presence of different metal ions. It is also suitable for testing the composition of a flowing liquid. Its disadvantage is that it requires complex and expensive equipment. (Ha)

  15. Thermal conductance of heat transfer interfaces for conductively cooled superconducting magnets

    Cooper, T.L.; Walters, J.D.; Fikse, T.H.

    1996-01-01

    Minimizing thermal resistances across interfaces is critical for efficient thermal performance of conductively cooled superconducting magnet systems. Thermal conductance measurements have been made for a flexible thermal coupling, designed to accommodate magnet-to-cryocooler and cryocooler-to-shield relative motion, and an interface incorporating Multilam designed as a sliding thermal connector for cryocoolers. Temperature changes were measured across each interface as a function of heat input. Thermal conductances have been calculated for each interface, and the impact of each interface on conductively cooled magnet systems will be discussed

  16. Electrical conductivity and magnetic permeability measurement of case hardened steels

    Tian, Yong

    2015-03-01

    For case carburized steels, electrical conductivity and magnetic permeability profiles are needed to develop model-based case depth characterization techniques for the purpose of nondestructive quality control. To obtain fast and accurate measurement of these material properties, four-point potential drop approaches are applied on circular-shaped discs cut from steel rings with different case depths. First, a direct current potential drop (DCPD) approach is applied to measure electrical conductivity. Subsequently, an alternating current potential drop (ACPD) approach is used to measure magnetic permeability. Practical issues in measurement design and implementation are discussed. Depth profiles of electrical conductivity and magnetic permeability are reported.

  17. Thermal conductivity of niobium single crystals in a magnetic field

    Gladun, C.; Vinzelberg, H.

    1980-01-01

    The thermal conductivity in longitudinal magnetic fields up to 5 T and in the temperature range 3.5 to 15 K is measured in two high purity niobium single crystals having residual resistivity ratios of 22700 and 19200 and orientations of the rod axis [110] and [100]. The investigations show that by means of the longitudinal magnetic field the thermal conductivity may decrease only to a limiting value. In the crystal directions [110] and [100] for the ratio of the thermal conductivity in zero field and the thermal conductivity in the saturation field the temperature-independent factors 1.92 and 1.27, respectively, are determined. With the aid of these factors the thermal conductivity in the normal state is evaluated from the measured values of thermal conductivity below Tsub(c) in the magnetic field. The different conduction and scattering mechanisms are discussed. (author)

  18. Crystal chemistry and magnetic properties of ternary rare earth sulfides

    Plug, C.M.; Rijksuniversiteit Leiden

    1977-01-01

    The results of magnetic measurements on two groups of ternary rare earth sulphides are described, the MLnS 2 (M=Li, Na, K) type of compounds and the series Ln 2 ZrS 5 , where Ln denotes one of the rare earths. None of these compounds is metallic, excluding the possibility of RKKY-interaction. In chapter II a survey of the relevant theory on magnetic properties and crystal field splitting is given. In spite of the similarity in chemical properties of the rare earths, the crystal chemistry of their compounds is rather complex. This is due to the lanthanide contraction. The third chapter deals with the description and classification of the numerous crystal structures of both ternary and binary rare earth sulphides that have been observed. Rather simple relations between various structures are presented using a new method of structure classification. The magnetic interactions expected to be based on superexchange via the anions, which is usually very structure dependent. Experiments to study the crystallographic ordering, applying both X-ray and electron diffraction methods and the results of the magnetic measurements on the compounds MLnS 2 are reported in chapter IV. The compounds Ln 2 ZrS 5 are candidates for a systematic study of the variation of the magnetic properties along the rare earth series. The results of magnetic measurements on these compounds are presented in chapter V, combined with the results of specific heat measurements. Also the magnetic structure of two representatives, Tb 2 ZrS 5 and Dy 2 ZrS 5 , determined by neutron diffraction experiments below the ordering temperature, is reported

  19. Kubo conductivity of a strongly magnetized two-dimensional plasma.

    Montgomery, D.; Tappert, F.

    1971-01-01

    The Kubo formula is used to evaluate the bulk electrical conductivity of a two-dimensional guiding-center plasma in a strong dc magnetic field. The particles interact only electrostatically. An ?anomalous' electrical conductivity is derived for this system, which parallels a recent result of Taylor and McNamara for the coefficient of spatial diffusion.

  20. High field nuclear magnetic resonance application to polysaccharide chemistry

    Vincendon, Marc

    1972-01-01

    Nuclear magnetic resonance has been applied to polysaccharide chemistry using time averaging technique and high fields (100 and 250 MHz). The three methyl signals of methyl cellulose and cellulose triacetate are separated, and the C-6 substituent has been identified. Biosynthesis of bacterial cellulose has been performed using deuterium labelled D-glucose and Acetobacter xylinum. Per-acetylated derivative of bacterial cellulose has been studied by NMR; this study permitted us to determine the quantity of deuterium on each position of the anhydro-glucose unit in the polymer. NMR has also been used to see the anomeric end chain of cellulose and amylose derivatives and to show the fixation of bromine and t-butyl group on the free anomeric end chain of cellulose triacetate. (author) [fr

  1. Magnetoresponsive conductive colloidal suspensions with magnetized carbon nanotubes

    Abdalla, Ahmed M. [Department of Engineering Physics, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada); Abdel Fattah, Abdel Rahman [Department of Mechanical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada); Ghosh, Suvojit [Department of Engineering Physics, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada); Puri, Ishwar K., E-mail: ikpuri@mcmaster.ca [Department of Engineering Physics, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada); Department of Mechanical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada)

    2017-01-01

    We synthesize a novel and hitherto unreported class of colloidal suspensions for which the dispersed phase, which consists of multiwall carbon nanotubes (MWNTs) decorated with magnetic nanoparticles (MNPs), is both magnetoresponsive and electrically conductive. Synthesis of the dispersed phase merges processes for producing ferrofluids and magnetic MWNTs (mMWNTs). We explore means to tune the properties of these magnetic conductive colloids (MCCs) by varying the (1) MNP material composition, and (2) MNP:MWNT (w/w) magnetization weight ratio (γ). The mMWNTs are examined using XRD, TEM, EDX and SQUID and MCCs are by measuring their zeta potential and electric conductivity. Magnetite (Fe{sub 3}O{sub 4}) MNPs, which possess a high Curie temperature, produce mMWNTs with high saturation magnetization that respond relatively weakly to temperature variations. Mn{sub 0.2}Cu{sub 0.2}Zn{sub 0.6}Fe{sub 2}O{sub 4} and Cu{sub 0.4}Zn{sub 0.6}Fe{sub 2}O{sub 4} MNPs with lower Curie temperatures are more sensitive to changing temperature. Increasing the MNP Cu content improves the electric conductivity of the corresponding MCC while increasing γ enhances its magnetic response. After γ is raised above a threshold value, mMWNT decoration on the CNT surface becomes nonuniform since the MNPs now agglomerate perpendicular to the nanotube surface. These colloidal suspensions are a promising new class of material that can be manipulated with a magnetic field to tune their electrical conductivity. - Highlights: ●We synthesize a novel and hitherto unreported class of colloidal suspensions. ●These colloidal suspensions are both magnetoresponsive and electrically conductive. ●The dispersed phase consists of MWNTs decorated with different magnetic nanoparticles. ●These colloids have enhanced magnetic response and electric conductivity (up to 169.5 mS cm{sup −1}). ●It is a promising new class of material that can be manipulated with a magnetic field.

  2. Review of technetium chemistry research conducted at the University of Nevada Las Vegas

    Poineau, F.; Weck, P.F.; Forster, P.; Hartmann, T.; Mausolf, E.; Silva, G.W.C.; Czerwinski, K.R.; Rodriguez, E.E.; Sattelberger, A.P.; Jarvinen, G.D.; Cheetham, A.K.

    2009-01-01

    The chemistry of technetium is being explored at the University of Nevada Las Vegas. Our goal is to investigate both the applied and fundamental aspects of technetium chemistry, with a special emphasis on synthesis, separations, and materials science. The synthetic chemistry focuses on metal-metal multiple bonding, oxides and halides. Synthesis and characterizations of (n-Bu 4 N) 2 Tc 2 X 8 , Tc 2 (O 2 CCH 3 ) 4 X 2 (X = Cl, Br), TcO 2 , Bi 2 Tc 2 O 7 , Bi 3 TcO 8 , TcBr 3 and TcBr 4 have been performed. The applied chemistry is related to the behavior of Tc in the UREX process. Separation of U/Tc has been conducted using anion exchange resin and metallic Tc waste form synthesized and characterized. (author)

  3. Thermoelectric conductivities at finite magnetic field and the Nernst effect

    Kim, Keun-Young; Kim, Kyung Kiu; Seo, Yunseok; Sin, Sang-Jin

    2015-01-01

    We study the thermoelectric conductivities of a strongly correlated system in the presence of a magnetic field by the gauge/gravity duality. We consider a class of Einstein-Maxwell-Dilaton theories with axion fields imposing momentum relaxation. General analytic formulas for the direct current (DC) conductivities and the Nernst signal are derived in terms of the black hole horizon data. For an explicit model study, we analyse in detail the dyonic black hole modified by momentum relaxation. In this model, for small momentum relaxation, the Nernst signal shows a bell-shaped dependence on the magnetic field, which is a feature of the normal phase of cuprates. We compute all alternating current (AC) electric, thermoelectric, and thermal conductivities by numerical analysis and confirm that their zero frequency limits precisely reproduce our analytic DC formulas, which is a non-trivial consistency check of our methods. We discuss the momentum relaxation effects on the conductivities including cyclotron resonance poles.

  4. Magnetic-field dependence of electrothermal conductivity in YBCO

    Marino, A.; Uribe, R. [Universidad del Tolima, Ibague (Colombia); Grupo de Superconductividad y Nuevos Materiales, Universidad Nacional de Colombia, Bogota (Colombia)

    2008-11-15

    Experimental measurements of the electrothermal conductivity (P) near T{sub c}, as a function of external magnetic field were carried out in undoped YBCO (123) superconducting samples. The electrothermal conductivity which relates electrical and thermal currents, depends on the applied magnetic field in high T{sub c} materials, contrary to conventional low T{sub c} superconductors where P is nearly independent of the magnetic field. The experimental P(B,T) data determined from resistivity and thermopower measurements were analyzed in terms of theoretical models and showed a behavior consistent with an order-parameter symmetry (OPS) of d{sub x{sup 2}-y{sup 2}}-wave type. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Micropatterning of Functional Conductive Polymers with Multiple Surface Chemistries in Register

    Lind, Johan Ulrik; Acikgöz, Canet; Daugaard, Anders Egede

    2012-01-01

    A versatile procedure is presented for fast and efficient micropatterning of multiple types of covalently bound surface chemistry in perfect register on and between conductive polymer microcircuits. The micropatterning principle is applied to several types of native and functionalized PEDOT (poly(3...... functionalized conjugated polymer systems....

  6. The magnetic-distortion probe: velocimetry in conducting fluids.

    Miralles, Sophie; Verhille, Gautier; Plihon, Nicolas; Pinton, Jean-François

    2011-09-01

    A new type of velocimeter, capable of local velocity measurements in conducting fluids, is introduced. The principle of the "magnetic-distortion probe" is based on the measurement of the induced magnetic field by the flow of a conducting fluid in the vicinity of a localized magnetic field. The new velocimeter has no moving parts, and can be enclosed in a sealed cap, easing the implementation in harsh environments, such as liquid metals. The proposed method allows one to probe both the continuous part and fluctuations of the velocity, the temporal and spatial resolution being linked to the actual geometric configuration of the probe. A prototype probe has been tested in a gallinstan pipe flow and in a fully turbulent flow of liquid gallium generated by the counter rotation of two coaxial impellers in a cylinder. The signals have been compared to a reference potential probe and show very good agreement both for time-averaged velocities and turbulent fluctuations. The prototype is shown to detect motion from a few cm s(-1) to a few m s(-1). Moreover, the use of the magnetic-distortion probe with large-scale applied magnetic field is discussed. © 2011 American Institute of Physics

  7. Radio frequency conductivity of plasma in inhomogeneous magnetic field

    Itoh, Sanae; Nishikawa, Kyoji; Fukuyama, Atsushi; Itoh, Kimitaka.

    1985-01-01

    Nonlocal conductivity tensor is obtained to study the kinetic effects on propagation and absorption of radio frequency (rf) waves in dispersive plasmas. Generalized linear propagator in the presence of the inhomogeneity of magnetic field strength along the field line is calculated. The influence of the inhomogeneity to the rf wave-energy deposition is found to be appreciable. Application to toroidal plasmas is shown. (author)

  8. Magnetic levitation by induced eddy currents in non-magnetic conductors and conductivity measurements

    Iniguez, J; Raposo, V; Flores, A G; Zazo, M; Hernandez-Lopez, A

    2005-01-01

    We report a study on magnetic levitation by induced ac currents in non-magnetic conductors at low frequencies. Our discussion, based on Faraday's induction law, allows us to distinguish the two components of the current responsible for levitation and heating, respectively. The experimental evaluation of the levitation force in a copper ring revealed the accuracy of our analysis, clearly illustrating its asymptotic behaviour versus frequency, and validating it for the qualitative analysis of magnetic levitation and heating in conductors of different shapes such as tubes and discs, composed of collections of conductive loops. The analysis of the results allows precise values of its electrical conductivity to be found. With the help of a simulation technique, this work also reveals the progressive deformation undergone by magnetic induction lines due to magnetic screening when frequency increases

  9. Magnetic levitation by induced eddy currents in non-magnetic conductors and conductivity measurements

    Iniguez, J; Raposo, V; Flores, A G; Zazo, M; Hernandez-Lopez, A [Departamento de Fisica Aplicada, Universidad de Salamanca, E-37071, Salamanca (Spain)

    2005-11-01

    We report a study on magnetic levitation by induced ac currents in non-magnetic conductors at low frequencies. Our discussion, based on Faraday's induction law, allows us to distinguish the two components of the current responsible for levitation and heating, respectively. The experimental evaluation of the levitation force in a copper ring revealed the accuracy of our analysis, clearly illustrating its asymptotic behaviour versus frequency, and validating it for the qualitative analysis of magnetic levitation and heating in conductors of different shapes such as tubes and discs, composed of collections of conductive loops. The analysis of the results allows precise values of its electrical conductivity to be found. With the help of a simulation technique, this work also reveals the progressive deformation undergone by magnetic induction lines due to magnetic screening when frequency increases.

  10. Transverse magnetic scattering by parallel conducting elliptic cylinders

    Sebak, A.

    1991-10-01

    A boundary value solution to the problem of transverse magnetic multiple scattering by M parallel perfectly conducting elliptic cylinders is presented. The solution is an exact one and based on the separation-of-variables technique and the addition theorem for Mathieu functions. It is expressed in terms of a system of simultaneous linear equations of infinite order, which is then truncated for numerical computations. Representative numerical results for the scattered field by two cylinders are then generated, for some selected sizes and orientations parameters, and presented.

  11. Effect of Synthesis Parameters on the Structure and Magnetic Properties of Magnetic Manganese Ferrite/Silver Composite Nanoparticles Synthesized by Wet Chemistry Method

    Huy, L.T.; Tam, L.T.; Phan, V.N.

    2016-01-01

    In the present work, magnetic manganese ferrite/silver (MnFe2O4-Ag) composite nanoparticles were synthesized by wet chemistry method. This synthesis process consists of two steps: first, the seed of manganese ferrite nanoparticles (MnFe2O4 NPs) was prepared by a coprecipitationmethod; second......, growth of silver nanoparticles (AgNPs) on the MnFe2O4 seed by modified photochemical reaction. We have conducted systematically the effects of synthesis parameters such as pH value, synthesis time, precursor salts concentration, mass ratio and stabilizing agents on the structure and magnetic properties......-prepared MnFe2O4-Ag magnetic nanocomposites display excellent properties of high crystallinity, long-term aggregation stability in aqueous medium, large saturation magnetization in the range of 15-20 emu/g, and small sizes of Ag-NPs similar to 20 nm. These exhibited properties made the MnFe2O4-Ag...

  12. Magnetic separation: its application in mining, waste purification, medicine, biochemistry and chemistry.

    Iranmanesh, M; Hulliger, J

    2017-10-02

    The use of strong magnetic field gradients and high magnetic fields generated by permanent magnets or superconducting coils has found applications in many fields such as mining, solid state chemistry, biochemistry and medical research. Lab scale or industrial implementations involve separation of macro- and nanoparticles, cells, proteins, and macromolecules down to small molecules and ions. Most promising are those attempts where the object to be separated is attached to a strong magnetic nanoparticle. Here, all kinds of specific affinity interactions are used to attach magnetic carrier particles to mainly objects of biological interest. Other attempts use a strong paramagnetic suspension for the separation of purely diamagnetic objects, such as bio-macromolecules or heavy metals. The application of magnetic separation to superconducting inorganic phases is of particular interest in combination with ceramic combinatorial chemistry to generate a library of e.g. cuprate superconductors.

  13. Electrically Conductive, Corrosion-Resistant Coatings Through Defect Chemistry for Metallic Interconnects

    Anil V. Virkar

    2006-01-01

    The principal objective of this work was to develop oxidation protective coatings for metallic interconnect based on a defect chemistry approach. It was reasoned that the effectiveness of a coating is dictated by oxygen permeation kinetics; the slower the permeation kinetics, the better the protection. All protective coating materials investigated to date are either perovskites or spinels containing metals exhibiting multiple valence states (Co, Fe, Mn, Cr, etc.). As a result, all of these oxides exhibit a reasonable level of electronic conductivity; typically at least about ∼0.05 S/cm at 800 C. For a 5 micron coating, this equates to a maximum ∼0.025 (Omega)cm 2 area specific resistance due to the coating. This suggests that the coating should be based on oxygen ion conductivity (the lower the better) and not on electronic conductivity. Measurements of ionic conductivity of prospective coating materials were conducted using Hebb-Wagner method. It was demonstrated that special precautions need to be taken to measure oxygen ion conductivity in these materials with very low oxygen vacancy concentration. A model for oxidation under a protective coating is presented. Defect chemistry based approach was developed such that by suitably doping, oxygen vacancy concentration was suppressed, thus suppressing oxygen ion transport and increasing effectiveness of the coating. For the cathode side, the best coating material identified was LaMnO 3 with Ti dopant on the Mn site (LTM). It was observed that LTM is more than 20 times as effective as Mn-containing spinels. On the anode side, LaCrO3 doped with Nb on the Cr site (LNC) was the material identified. Extensive oxidation kinetics studies were conducted on metallic alloy foils with coating ∼1 micron in thickness. From these studies, it was projected that a 5 micron coating would be sufficient to ensure 40,000 h life

  14. Electron spin interactions in chemistry and biology fundamentals, methods, reactions mechanisms, magnetic phenomena, structure investigation

    Likhtenshtein, Gertz

    2016-01-01

    This book presents the versatile and pivotal role of electron spin interactions in nature. It provides the background, methodologies and tools for basic areas related to spin interactions, such as spin chemistry and biology, electron transfer, light energy conversion, photochemistry, radical reactions, magneto-chemistry and magneto-biology. The book also includes an overview of designing advanced magnetic materials, optical and spintronic devices and photo catalysts. This monograph appeals to scientists and graduate students working in the areas related to spin interactions physics, biophysics, chemistry and chemical engineering.

  15. Magnet Fall inside a Conductive Pipe: Motion and the Role of the Pipe Wall Thickness

    Donoso, G.; Ladera, C. L.; Martin, P.

    2009-01-01

    Theoretical models and experimental results are presented for the retarded fall of a strong magnet inside a vertical conductive non-magnetic tube. Predictions and experimental results are in good agreement modelling the magnet as a simple magnetic dipole. The effect of varying the pipe wall thickness on the retarding magnetic drag is studied for…

  16. Nuclear magnetic resonance spectroscopy in organic chemistry. 2. ed.

    Zschunke, A.

    1977-01-01

    The fundamentals of nuclear magnetic resonance spectroscopy are discussed only briefly. The emphasis is laid on developing reader's ability to evaluate resonance spectra. The following topics are covered: principles of nuclear magnetic resonance spectroscopy; chemical shift and indirect nuclear spin coupling constants and their relation to the molecular structure; analysis of spectra; and uses for structural analysis and solution of kinetic problems, mainly with regard to organic compounds. Of interest to chemists and graduate students who want to make themselves acquainted with nuclear magnetic resonance spectroscopy

  17. Electric Conductivity and Dielectric-Breakdown Behavior for Polyurethane Magnetic Elastomers.

    Sasaki, Shuhei; Tsujiei, Yuri; Kawai, Mika; Mitsumata, Tetsu

    2017-02-23

    The electric-voltage dependence of the electric conductivity for cross-linked and un-cross-linked magnetic elastomers was measured at various magnetic fields, and the effect of cross-linking on the electric conductivity and the dielectric-breakdown behavior was investigated. The electric conductivity for un-cross-linked elastomers at low voltages was independent of magnetic fields and the volume fraction of magnetic particles, indicating the electric conduction in the polyurethane matrix. At high voltages, the electric conductivity increased with the magnetic field, showing the electric conduction via chains of magnetic particles. On the other hand, the electric conductivity at low voltages for cross-linked elastomers with volume fractions below 0.06 was independent of the magnetic field, suggesting the electric conduction in the polyurethane matrix. At volume fractions above 0.14, the electric conductivity increased with the magnetic field, suggesting the electric conduction via chains of magnetic particles. At high voltages, the electric conductivity for cross-linked elastomers with a volume fraction of 0.02 was independent of the magnetic field, indicating the electric conduction through the polyurethane matrix. At volume fractions above 0.06, the electric conductivity suddenly increased at a critical voltage, exhibiting the dielectric breakdown at the bound layer of magnetic particles and/or the discontinuous part between chains.

  18. The European Register of Specialists in Clinical Chemistry and Laboratory Medicine: Code of Conduct, Version 2--2008.

    McMurray, Janet

    2009-01-01

    In 1997, the European Communities Confederation of Clinical Chemistry and Laboratory Medicine (EC4) set up a Register for European Specialists in Clinical Chemistry and Laboratory Medicine. The operation of the Register is undertaken by a Register Commission (EC4RC). During the last 10 years, more than 2000 specialists in Clinical Chemistry and Laboratory Medicine have joined the Register. In 2007, EC4 merged with the Federation of European Societies of Clinical Chemistry and Laboratory Medicine (FESCC) to form the European Federation of Clinical Chemistry and Laboratory Medicine (EFCC). A Code of Conduct was adopted in 2003 and a revised and updated version, taking account particularly of the guidelines of the Conseil Européen des Professions Libérales (CEPLIS) of which EFCC is a member, is presented in this article. The revised version was approved by the EC4 Register Commission and by the EFCC Executive Board in Paris on 6 November, 2008.

  19. Magnet fall inside a conductive pipe: motion and the role of the pipe wall thickness

    Donoso, G; Ladera, C L; Martin, P [Departamento de Fisica, Universidad Simon BolIvar, Apdo. 89000, Caracas 1080 (Venezuela, Bolivarian Republic of)], E-mail: clladera@usb.ve, E-mail: pmartin@usb.ve

    2009-07-15

    Theoretical models and experimental results are presented for the retarded fall of a strong magnet inside a vertical conductive non-magnetic tube. Predictions and experimental results are in good agreement modelling the magnet as a simple magnetic dipole. The effect of varying the pipe wall thickness on the retarding magnetic drag is studied for pipes of different materials. Conductive pipes of thinner walls produce less dragging force and the retarded fall of the magnet is seen to consist of an initial transient accelerated regime followed by a stage of uniform motion. Alternative models of the magnet field are also presented that improve the agreement between theory and experiments.

  20. Protection of Hardware: Powering Systems (Power Converter, Normal Conducting, and Superconducting Magnets)

    Pfeffer, H. [Fermilab; Flora, B. [Fermilab; Wolff, D. [Fermilab

    2016-01-01

    Along with the protection of magnets and power converters, we have added a section on personnel protection because this is our highest priority in the design and operation of power systems. Thus, our topics are the protection of people, power converters, and magnet loads (protected from the powering equipment), including normal conducting magnets and superconducting magnets.

  1. Conduction cooled high temperature superconducting dipole magnet for accelerator applications

    Zangenberg, N.; Nielsen, G.; Hauge, N.

    2012-01-01

    A 3T proof-of-principle dipole magnet for accelerator applications, based on 2nd generation high temperature superconducting tape was designed, built, and tested by a consortium under the lead of Danfysik. The magnet was designed to have a straight, circular bore with a good field region of radius...

  2. Conductance quantization in magnetic nanowires electrodeposited in nanopores

    Elhoussine, F.; Mátéfi-Tempfli, Stefan; Encinas, A.

    2002-01-01

    Magnetic nanocontacts have been prepared by a templating method that involves the electrodeposition of Ni within the pores of track-etched polymer membranes. The nanocontacts are made at the extremity of a single Ni nanowire either inside or outside the pores. The method is simple, flexible...... degeneracy. Our fabrication method enables future investigation of ballistic spin transport phenomena in electrodeposited magnetic nanocontacts....

  3. Conductance of graphene based normal-superconductor junction with double magnetic barriers

    Abdollahipour, B.; Mohebalipour, A.; Maleki, M. A.

    2018-05-01

    We study conductance of a graphene based normal metal-superconductor junction with two magnetic barriers. The magnetic barriers are induced via two applied magnetic fields with the same magnitudes and opposite directions accompanied by an applied electrostatic potential. We solve Dirac-Bogoliubov-De-Gennes (DBdG) equation to calculate conductance of the junction. We find that applying the magnetic field leads to suppression of the Andreev reflection and conductance for all energies. On the other hand, we observe a crossover from oscillatory to tunneling behavior of the conductance as a function of the applied potential by increasing the magnetic field.

  4. Anomalous Thermal Conductivity and Magnetic Torque Response in the Honeycomb Magnet α -RuCl3

    Leahy, Ian A.; Pocs, Christopher A.; Siegfried, Peter E.; Graf, David; Do, S.-H.; Choi, Kwang-Yong; Normand, B.; Lee, Minhyea

    2017-05-01

    We report on the unusual behavior of the in-plane thermal conductivity κ and torque τ response in the Kitaev-Heisenberg material α -RuCl3 . κ shows a striking enhancement with linear growth beyond H =7 T , where magnetic order disappears, while τ for both of the in-plane symmetry directions shows an anomaly at the same field. The temperature and field dependence of κ are far more complex than conventional phonon and magnon contributions, and require us to invoke the presence of unconventional spin excitations whose properties are characteristic of a field-induced spin-liquid phase related to the enigmatic physics of the Kitaev model in an applied magnetic field.

  5. Chemistry

    Ferris, L.M.

    1975-01-01

    Research and development activities dealing with the chemical problems related to design and ultimate operation of molten-salt reactor systems are described. An experimental test stand was constructed to expose metallurgical test specimens to Te 2 vapor at defined temperatures and deposition rates. To better define the chemistry of fluoroborate coolant, several aspects are being investigated. The behavior of hydroxy and oxy compounds in molten NaBF 4 is being investigated to define reactions and compounds that may be involved in corrosion and/or could be involved in methods for trapping tritium. Two corrosion products of Hastelloy N, Na 3 CrF 6 and Na 5 Cr 3 F 14 , were identified from fluoroborate systems. The evaluation of fluoroborate and alternate coolants continued. Research on the behavior of hydrogen and its isotopes is summarized. The solubilities of hydrogen, deuterium, and helium in Li 2 BeF 4 are very low. The sorption of tritium on graphite was found to be significant (a few milligrams of tritium per kilogram of graphite), possibly providing a means of sequestering a portion of the tritium produced. Development of analytical methods continued with emphasis on voltammetric and spectrophotometric techniques for the in-line analysis of corrosion products such as Fe 2+ and Cr 3+ and the determination of the U 3+ /U 4+ ratio in MSBR fuel salt. Similar studies were conducted with the NaBF 4 --NaF coolant salt. Information developed during the previous operation of the CSTF has been assessed and used to formulate plans for evaluation of in-line analytical methods in future CSTF operations. Electroanalytical and spectrophotometric research suggests that an electroactive protonic species is present in molten NaBF 4 --NaF, and that this species rapidly equilibrates with a volatile proton-containing species. Data obtained from the CSTF indicated that tritium was concentrated in the volatile species. (JGB)

  6. Effect of magnetic field on thermal conductivity and viscosity of a magnetic nanofluid loaded with carbon nanotubes

    Shahsavar, Amin [Kermanshah University of Technology, Kermanshah (Iran, Islamic Republic of); Salimpour, Mohammad Reza; Saghafian, Mohsen [Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Shafii, M. B. [Sharif University of Technology, Tehran(Iran, Islamic Republic of)

    2016-02-15

    The present work examines experimentally the effect of magnetic field on the viscosity and thermal conductivity of a hybrid nanofluid containing tetramethylammonium hydroxide (TMAH) coated Fe{sub 3}O{sub 4} nanoparticles and Gum arabic (GA) coated carbon nanotubes (CNTs). The hybrid nanofluid was prepared by using ultrasonic dispersion method. Magnetic field was created by a pair of spaced apart magnet plates. The effect of temperature on the time variation of thermal conductivity under applied magnetic field was also investigated. According to the results of this study, viscosity of the hybrid nanofluid increases with the strength of magnetic field, while it decreases with the increase of temperature. Additionally, it is found that the hybrid nanofluid behaves as a shear thinning fluid at low shear rates while it exhibits Newtonian behavior at high shear rates. Furthermore, results show that when an external magnetic field is applied to the studied magnetic nanofluids, the thermal conductivity experiences a peak.

  7. Spin and time-resolved magnetic resonance in radiation chemistry. Recent developments and perspectives

    Shkrob, I.A.; Trifunac, A.D.

    1997-01-01

    Time-resolved pulsed EPR and ODMR in studies on early events in radiation chemistry are examined. It is concluded that these techniques yield valuable and diverse information about chemical reactions in spurs, despite the fact that the spur reactions occur on a time scale that is much shorter than the time resolution of these methods. Several recent examples include EPR of H/D atoms in vitreous silica and cryogenic liquids and ODMR of doped alkane solids and amorphous semiconductors. It is argued that a wider use of time-resolved magnetic resonance methods would benefit the studies on radiation chemistry of disordered solids, simple liquids, and polymers. (author)

  8. Super Conducting and Conventional Magnets Test & Mapping Facilities

    Federal Laboratory Consortium — Vertical Magnet Test Facility: Accommodate a device up to 3.85 m long, 0.61 m diameter, and 14,400 lbs. Configured for 5 psig sub-cooled liquid helium bath cooling...

  9. Magnetization pinning in conducting films demonstrated using broadband ferromagnetic resonance

    Kostylev, M.; Stashkevich, A. A.; Adeyeye, A. O.; Shakespeare, C.; Kostylev, N.; Ross, N.; Kennewell, K.; Magaraggia, R.; Roussigné, Y.; Stamps, R. L.

    2010-11-01

    The broadband microstrip ferromagnetic resonance (FMR), cavity FMR, and Brillouin light scattering spectroscopy techniques have been applied for detection and characterization of a magnetic inhomogeneity in a film sample. In the case of a 100 nm thick permalloy film, an additional magnetically depleted top sublayer has been detected due to pinning effect it produces on the magnetization in the bulk of the film. The pinning results in appearance of an exchange standing spin wave mode in the broadband FMR absorption spectrum, whose amplitudes are different depending on whether the film or the film substrate faces the microstrip transducer. Comparison of the experimental amplitudes for this mode with results of our theory for both film placements revealed that the depleted layer is located at the film surface facing away from the film substrate. Subsequent broadband FMR characterization of a large number of other presumably single-layer films with thicknesses in the range 30-100 nm showed the same result.

  10. A planar conducting microstructure to guide and confine magnetic beads to a sensing zone

    Gooneratne, Chinthaka Pasan

    2011-08-01

    A novel planar conducting microstructure is proposed to transport and confine magnetic micro/nano beads to a sensing zone. Manipulation and concentration of magnetic beads are achieved by employing square-shaped conducting micro-loops, with a few hundred nano-meters in thickness, arranged in a unique fashion. These microstructures are designed to produce high magnetic field gradients which are directly proportional to the force applied to manipulate the magnetic beads. Furthermore, the size of the microstructures allows greater maneuverability and control of magnetic beads than what could be achieved by permanent magnets. The aim of the microstructures is to guide magnetic beads from a large area and confine them to a smaller area where for example quantification would take place. Experiments were performed with different concentrations of 2 μm diameter magnetic beads. Experimental results showed that magnetic beads could be successfully guided and confined to the sensing zone. © 2011 Elsevier B.V. All rights reserved.

  11. Chemistry

    Ferris, L.M.

    1975-01-01

    The chemical research and development efforts related to the design and ultimate operation of molten-salt breeder reactor systems are concentrated on fuel- and coolant-salt chemistry, including the development of analytical methods for use in these systems. The chemistry of tellurium in fuel salt is being studied to help elucidate the role of this element in the intergranular cracking of Hastelloy N. Studies were continued of the effect of oxygen-containing species on the equilibrium between dissolved UF 3 and dissolved UF 4 , and, in some cases, between the dissolved uranium fluorides and graphite, and the UC 2 . Several aspects of coolant-salt chemistry are under investigation. Hydroxy and oxy compounds that could be formed in molten NaBF 4 are being synthesized and characterized. Studies of the chemistry of chromium (III) compounds in fluoroborate melts were continued as part of a systematic investigation of the corrosion of structural alloys by coolant salt. An in-line voltammetric method for determining U 4+ /U 3+ ratios in fuel salt was tested in a forced-convection loop over a six-month period. (LK)

  12. The nature of science and technology for pre-service chemistry teacher: A case of techno-chemistry experiment "From Stannum Metalicum to conductive glass"

    Mudzakir, A.; Widhiyanti, T.; Hernani, Arifin, M.; Lestari, A. N.; Jauhariansyah, S.

    2017-08-01

    The study was conducted to address the problems related to low Indonesian students' scientific literacy as revealed in the PISA (Program for International Student Assessment) since 2000-2015. Science teachers (e.g. chemistry teacher) must recognize the nature of science (NOS) to assist their students in preparing an explanation of a phenomenon scientifically correctly. Teachers also need to understand critically about nature of technology (NOT) and it relationship with science as well as society. To integrate those two kinds of knowledge (NOS and NOT), we can conduct a techno-science activity, which integrate the technology to science course in pre-service teacher education program, so that they can improve their knowledge about nature of science and technology (NOST) and pedagogical content knowledge related to NOST. The purpose of this study was to construct an inquiry based laboratory activity worksheet for making conductive glass so that the pre-service teacher could explain how the structure of the semiconductor Fluor doped Tin Oxide (SnO2.F) affect their performance. This study we conducted, described how to design a pre-service chemistry teacher education course that can improve recognizing view of NOST by using a framework called model of educational reconstruction (MER). The scientific activities in the course were guided inquiry based techno-chemistry experiments involving "From Stannum Metallicum to Conductive Glass". Conductive glasses are interesting subject research for several reason. The application of this technology could be found on solar cell, OLED, and display panel. The doped Tin dioxide has been deposited on glass substrate using the spray pyrolysis technique at 400-550°C substrate temperature, 4-5 times, 20 cm gap between glass and sprayer and 450 angle to form a thin film which will act as electrical contact. The resistivity is about 0.5 - 15Ω. The product resulted on this study was rated by several expert to find if the worksheet could

  13. Conductive, magnetic and structural properties of multilayer films

    Kotov, L. N.; Turkov, V. K.; Vlasov, V. S.; Lasek, M. P.; Kalinin, Yu E.; Sitnikov, A. V.

    2013-12-01

    Composite-semiconductor and composite-dielectric multilayer films were obtained by the ion beam sputtering method in the argon and hydrogen atmospheres with compositions: {[(Co45-Fe45-Zr10)x(Al2O3)y]-[α-Si]}120, {[(Co45-Ta45-Nb10)x(SiO2)y]-[SiO2]}56, {[(Co45-Fe45-Zr10)x(Al2O3)y]-[α-Si:H]}120. The images of surface relief and distribution of the dc current on composite layer surface were obtained with using of atomic force microscopy (AFM). The dependencies of specific electric resistance, ferromagnetic resonance (FMR) fields and width of line on metal (magnetic) phase concentration x and nanolayers thickness of multilayer films were obtained. The characteristics of FMR depend on magnetic interaction among magnetic granules in the composite layers and between the layers. These characteristics depend on the thickness of composite and dielectric or semiconductor nanolayers. The dependences of electric microwave losses on the x and alternating field frequency were investigated.

  14. Deterioration in effective thermal conductivity of aqueous magnetic nanofluids

    Altan, C.L.; Gurten, B.; Sommerdijk, N.A.J.M.; Bucak, S.

    2014-01-01

    Common heat transfer fluids have low thermal conductivities, which decrease their efficiency in many applications. On the other hand, solids have much higher thermal conductivity values. Previously, it was shown that the addition of different nanoparticles to various base fluids increases the

  15. Chemistry

    Ferris, L.M.

    1976-01-01

    Research progress is reported in programs on fuel-salt chemistry, properties of compounds in the Li--Te system, Te spectroscopy UF 4 --H equilibria, porous electrode studies of molten salts, fuel salt-coolant salt reactions, thermodynamic properties of transition-metal fluorides, and properties of sodium fluoroborate. Developmental work on analytical methods is summarized including in-line analysis of molten MSBR fuel, analysis of coolant-salts for tritium, analysis of molten LiF--BeF 2 --ThF 4 for Fe and analysis of LiF--BeF--ThF 4 for Te

  16. Magnetic field mediated conductance oscillation in graphene p–n junctions

    Cheng, Shu-Guang

    2018-04-01

    The electronic transport of graphene p–n junctions under perpendicular magnetic field is investigated in theory. Under low magnetic field, the transport is determined by the resonant tunneling of Landau levels and conductance versus magnetic field shows a Shubnikov–de Haas oscillation. At higher magnetic field, the p–n junction subjected to the quasi-classical regime and the formation of snake states results in periodical backscattering and transmission as magnetic field varies. The conductance oscillation pattern is mediated both by magnetic field and the carrier concentration on bipolar regions. For medium magnetic field between above two regimes, the combined contributions of resonant tunneling, snake states oscillation and Aharanov–Bohm interference induce irregular oscillation of conductance. At very high magnetic field, the system is subjected to quantum Hall regime. Under disorder, the quantum tunneling at low magnetic field is slightly affected and the oscillation of snake states at higher magnetic field is suppressed. In the quantum Hall regime, the conductance is a constant as predicted by the mixture rule.

  17. Electron Gas Dynamic Conductivity Tensor on the Nanotube Surface in Magnetic Field

    A. M. Ermolaev

    2011-01-01

    Full Text Available Kubo formula was derived for the electron gas conductivity tensor on the nanotube surface in longitudinal magnetic field considering spatial and time dispersion. Components of the degenerate and nondegenerate electron gas conductivity tensor were calculated. The study has showed that under high electron density, the conductivity undergoes oscillations of de Haas-van Alphen and Aharonov-Bohm types with the density of electrons and magnetic field changes.

  18. Conduction mechanism of nitronyl-nitroxide molecular magnetic compounds

    Dotti, N.; Heintze, E.; Slota, M.; Hübner, R.; Wang, F.; Nuss, J.; Dressel, M.; Bogani, L.

    2016-04-01

    We investigate the conduction mechanisms of nitronyl-nitroxide (NIT) molecular radicals, as useful for the creation of nanoscopic molecular spintronic devices, finding that it does not correspond to standard Mott behavior, as previously postulated. We provide a complete investigation using transport measurements, low-energy, sub-THz spectroscopy and introducing differently substituted phenyl appendages. We show that a nontrivial surface-charge-limited regime is present in addition to the standard low-voltage Ohmic conductance. Scaling analysis allows one to determine all the main transport parameters for the compounds and highlights the presence of charge-trapping effects. Comparison among the different compounds shows the relevance of intermolecular stacking between the aromatic ring of the phenyl appendix and the NIT motif in the creation of useful electron transport channels. The importance of intermolecular pathways is further highlighted by electronic structure calculations, which clarify the nature of the electronic channels and their effect on the Mott character of the compounds.

  19. Magnetic field induced augmented thermal conduction phenomenon in magneto-nanocolloids

    Katiyar, Ajay; Dhar, Purbarun; Nandi, Tandra; Das, Sarit K.

    2016-01-01

    Magnetic field induced augmented thermal conductivity of magneto-nanocolloids involving nanoparticles, viz. Fe_2O_3, Fe_3O_4, NiO and Co_3O_4 dispersed in different base fluids have been reported. Experiments reveal the augmented thermal transport under external applied magnetic field. A maximum thermal conductivity enhancement ∼114% is attained at 7.0 vol% concentration and 0.1 T magnetic flux density for Fe_3O_4/EG magneto-nanocolloid. However, a maximum ∼82% thermal conductivity enhancement is observed for Fe_3O_4/kerosene magneto-nanocolloid for the same concentration but relatively at low magnetic flux density (∼0.06 T). Thereby, a strong effect of fluid as well as particle physical properties on the chain formation propensity, leading to enhanced conduction, in such systems is observed. Co_3O_4 nanoparticles show insignificant effect on the thermal conductivity enhancement of MNCs due to their minimal magnetic moment. A semi-empirical approach has been proposed to understand the mechanism and physics behind the thermal conductivity enhancement under external applied magnetic field, in tune with near field magnetostatic interactions as well as Neel relaxivity of the magnetic nanoparticles. Furthermore, the model is able to predict the phenomenon of enhanced thermal conductivity as a function of physical parameters and shows good agreement with the experimental observations. - Highlights: • Heat conduction in magneto-nanocolloids augments tremendously under magnetic field. • Oxide nanoparticles of Fe, Ni and Co dispersed in variant base fluids are used. • Enhancement in heat conduction is due to the formation of thermally conductive chains. • Proposed semi-empirical model shows good agreement with the experimental results.

  20. Magnetic field induced augmented thermal conduction phenomenon in magneto-nanocolloids

    Katiyar, Ajay, E-mail: ajay_cim@rediffmail.com [Research and Innovation Centre (DRDO), Indian Institute of Technology Madras Research Park, Chennai 600 113 (India); Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India); Dhar, Purbarun, E-mail: purbarun@iitrpr.ac.in [Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India); Nandi, Tandra, E-mail: tandra_n@rediffmail.com [Defence Materials and Stores Research and Development Establishment (DRDO), G.T. Road, Kanpur 208 013 (India); Das, Sarit K., E-mail: skdas@iitrpr.ac.in [Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India)

    2016-12-01

    Magnetic field induced augmented thermal conductivity of magneto-nanocolloids involving nanoparticles, viz. Fe{sub 2}O{sub 3}, Fe{sub 3}O{sub 4}, NiO and Co{sub 3}O{sub 4} dispersed in different base fluids have been reported. Experiments reveal the augmented thermal transport under external applied magnetic field. A maximum thermal conductivity enhancement ∼114% is attained at 7.0 vol% concentration and 0.1 T magnetic flux density for Fe{sub 3}O{sub 4}/EG magneto-nanocolloid. However, a maximum ∼82% thermal conductivity enhancement is observed for Fe{sub 3}O{sub 4}/kerosene magneto-nanocolloid for the same concentration but relatively at low magnetic flux density (∼0.06 T). Thereby, a strong effect of fluid as well as particle physical properties on the chain formation propensity, leading to enhanced conduction, in such systems is observed. Co{sub 3}O{sub 4} nanoparticles show insignificant effect on the thermal conductivity enhancement of MNCs due to their minimal magnetic moment. A semi-empirical approach has been proposed to understand the mechanism and physics behind the thermal conductivity enhancement under external applied magnetic field, in tune with near field magnetostatic interactions as well as Neel relaxivity of the magnetic nanoparticles. Furthermore, the model is able to predict the phenomenon of enhanced thermal conductivity as a function of physical parameters and shows good agreement with the experimental observations. - Highlights: • Heat conduction in magneto-nanocolloids augments tremendously under magnetic field. • Oxide nanoparticles of Fe, Ni and Co dispersed in variant base fluids are used. • Enhancement in heat conduction is due to the formation of thermally conductive chains. • Proposed semi-empirical model shows good agreement with the experimental results.

  1. NON-EQUILIBRIUM CHEMISTRY OF DYNAMICALLY EVOLVING PRESTELLAR CORES. II. IONIZATION AND MAGNETIC FIELD

    Tassis, Konstantinos; Willacy, Karen; Yorke, Harold W.; Turner, Neal J.

    2012-01-01

    We study the effect that non-equilibrium chemistry in dynamical models of collapsing molecular cloud cores has on measurements of the magnetic field in these cores, the degree of ionization, and the mean molecular weight of ions. We find that OH and CN, usually used in Zeeman observations of the line-of-sight magnetic field, have an abundance that decreases toward the center of the core much faster than the density increases. As a result, Zeeman observations tend to sample the outer layers of the core and consistently underestimate the core magnetic field. The degree of ionization follows a complicated dependence on the number density at central densities up to 10 5 cm –3 for magnetic models and 10 6 cm –3 in non-magnetic models. At higher central densities, the scaling approaches a power law with a slope of –0.6 and a normalization which depends on the cosmic-ray ionization rate ζ and the temperature T as (ζT) 1/2 . The mean molecular weight of ions is systematically lower than the usually assumed value of 20-30, and, at high densities, approaches a value of 3 due to the asymptotic dominance of the H + 3 ion. This significantly lower value implies that ambipolar diffusion operates faster.

  2. Surface-Chemistry-Mediated Control of Individual Magnetic Helical Microswimmers in a Swarm.

    Wang, Xiaopu; Hu, Chengzhi; Schurz, Lukas; De Marco, Carmela; Chen, Xiangzhong; Pané, Salvador; Nelson, Bradley J

    2018-05-31

    Magnetic helical microswimmers, also known as artificial bacterial flagella (ABFs), perform 3D navigation in various liquids under low-strength rotating magnetic fields by converting rotational motion to translational motion. ABFs have been widely studied as carriers for targeted delivery and release of drugs and cells. For in vivo/ in vitro therapeutic applications, control over individual groups of swimmers within a swarm is necessary for several biomedical applications such as drug delivery or small-scale surgery. In this work, we present the selective control of individual swimmers in a swarm of geometrically and magnetically identical ABFs by modifying their surface chemistry. We confirm experimentally and analytically that the forward/rotational velocity ratio of ABFs is independent of their surface coatings when the swimmers are operated below their step-out frequency (the frequency requiring the entire available magnetic torque to maintain synchronous rotation). We also show that ABFs with hydrophobic surfaces exhibit larger step-out frequencies and higher maximum forward velocities compared to their hydrophilic counterparts. Thus, selective control of a group of swimmers within a swarm of ABFs can be achieved by operating the selected ABFs at a frequency that is below their step-out frequencies but higher than the step-out frequencies of unselected ABFs. The feasibility of this method is investigated in water and in biologically relevant solutions. Selective control is also demonstrated inside a Y-shaped microfluidic channel. Our results present a systematic approach for realizing selective control within a swarm of magnetic helical microswimmers.

  3. Thermal and structural analysis of a cryogenic conduction cooling system for a HTS NMR magnet

    In, Se Hwan; Hong, Yong Jun; Yeom, Han Kil; Ko, Hyo Bong; Park, Seong Je [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

    2016-03-15

    The superconducting NMR magnets have used cryogen such as liquid helium for their cooling. The conduction cooling method using cryocoolers, however, makes the cryogenic cooling system for NMR magnets more compact and user-friendly than the cryogen cooling method. This paper describes the thermal and structural analysis of a cryogenic conduction cooling system for a 400 MHz HTS NMR magnet, focusing on the magnet assembly. The highly thermo-conductive cooling plates between HTS double pancake coils are used to transfer the heat generated in coils, namely Joule heating at lap splice joints, to thermal link blocks and finally the cryocooler. The conduction cooling structure of the HTS magnet assembly preliminarily designed is verified by thermal and structural analysis. The orthotropic thermal properties of the HTS coil, thermal contact resistance and radiation heat load are considered in the thermal analysis. The thermal analysis confirms the uniform temperature distribution for the present thermal design of the NMR magnet within 0.2 K. The mechanical stress and the displacement by the electromagnetic force and the thermal contraction are checked to verify structural stability. The structural analysis indicates that the mechanical stress on each component of the magnet is less than its material yield strength and the displacement is acceptable in comparison with the magnet dimension.

  4. Can We Probe the Conductivity of the Lithosphere and Upper Mantle Using Satellite Tidal Magnetic Signals?

    Schnepf, N. R.; Kuvshinov, A.; Sabaka, T.

    2015-01-01

    A few studies convincingly demonstrated that the magnetic fields induced by the lunar semidiurnal (M2) ocean flow can be identified in satellite observations. This result encourages using M2 satellite magnetic data to constrain subsurface electrical conductivity in oceanic regions. Traditional satellite-based induction studies using signals of magnetospheric origin are mostly sensitive to conducting structures because of the inductive coupling between primary and induced sources. In contrast, galvanic coupling from the oceanic tidal signal allows for studying less conductive, shallower structures. We perform global 3-D electromagnetic numerical simulations to investigate the sensitivity of M2 signals to conductivity distributions at different depths. The results of our sensitivity analysis suggest it will be promising to use M2 oceanic signals detected at satellite altitude for probing lithospheric and upper mantle conductivity. Our simulations also suggest that M2 seafloor electric and magnetic field data may provide complementary details to better constrain lithospheric conductivity.

  5. Complementary variational principle method applied to thermal conductivities of a plasma in a uniform magnetic field

    Sehgal, A K; Gupta, S C [Punjabi Univ., Patiala (India). Dept. of Physics

    1982-12-14

    The complementary variational principles method (CVP) is applied to the thermal conductivities of a plasma in a uniform magnetic field. The results of computations show that the CVP derived results are very useful.

  6. Roles of Bulk and Surface Chemistry in the Oxygen Exchange Kinetics and Related Properties of Mixed Conducting Perovskite Oxide Electrodes

    Nicola H. Perry

    2016-10-01

    Full Text Available Mixed conducting perovskite oxides and related structures serving as electrodes for electrochemical oxygen incorporation and evolution in solid oxide fuel and electrolysis cells, respectively, play a significant role in determining the cell efficiency and lifetime. Desired improvements in catalytic activity for rapid surface oxygen exchange, fast bulk transport (electronic and ionic, and thermo-chemo-mechanical stability of oxygen electrodes will require increased understanding of the impact of both bulk and surface chemistry on these properties. This review highlights selected work at the International Institute for Carbon-Neutral Energy Research (I2CNER, Kyushu University, set in the context of work in the broader community, aiming to characterize and understand relationships between bulk and surface composition and oxygen electrode performance. Insights into aspects of bulk point defect chemistry, electronic structure, crystal structure, and cation choice that impact carrier concentrations and mobilities, surface exchange kinetics, and chemical expansion coefficients are emerging. At the same time, an understanding of the relationship between bulk and surface chemistry is being developed that may assist design of electrodes with more robust surface chemistries, e.g., impurity tolerance or limited surface segregation. Ion scattering techniques (e.g., secondary ion mass spectrometry, SIMS, or low energy ion scattering spectroscopy, LEIS with high surface sensitivity and increasing lateral resolution are proving useful for measuring surface exchange kinetics, diffusivity, and corresponding outer monolayer chemistry of electrodes exposed to typical operating conditions. Beyond consideration of chemical composition, the use of strain and/or a high density of active interfaces also show promise for enhancing performance.

  7. Electrical conductivity of a fully ionized plasma in a magnetic field

    Vaucher, B.; Vaclavik, J.; Schneider, H.

    1975-01-01

    In this experimental work the authors have investigated the electrical conductivity of a homogeneous fully ionized plasma in a homogeneous magnetic field. In particular, the conductivity perpendicular to the magnetic field was studied by means of the magnetoacoustic resonance for different values of the parameter ωsub(c)/γsub(ei) where ωsub(c) is the electron cyclotron frequency and γsub(ei) is the collision frequency between electrons and ions. (Auth.)

  8. Directing functional chemistries on micropatterned conducting polymers for all-polymer cell analysis microsystems

    Lind, Johan Ulrik; Daugaard, Anders Egede; Andresen, Thomas Lars

    Micrometer scale electrical circuits of PEDOT (poly(3,4-dioxythiophene)) were created by locally oxidizing PEDOT thin films with an agarose stamp containing the oxidizing agent NaOCl. The oxidized PEDOT was removed completely by applying detergents. The process was sufficiently mild that chemical...... groups on the underlying substrate, such as azides or alkynes, were preserved for subsequent specific functionalization. Moreover entire PMOXA (poly(2-methyl-2-oxazoline)) films preventing cell binding could be hidden below the PEDOT and be re-exposed upon stamping, allowing for cell capturing...... microelectrodes on a cell non-adhesive background. Chemically functionalized PEDOT types permitted the introduction of multiple additional types of micropatterned chemistry....

  9. Time-dependent behavior of magnetic fields confined by conducting walls

    Kidder, R.E.; Cecil, A.B.

    1983-01-01

    An equation is derived which describes the total current flowing in a moving conducting surface surrounding a magnetic field, where diffusion of the field into the conductor is taken into account. Analytic and numerical solutions of the current equation are obtained for the cases of exponential and linear compression of the magnetic field with time, respectively. It is assumed that the electrical conductivity is constant, that the conducting surfaces are axially symmetric, and that the thickness and radius of curvature of the conducting walls is large compared with the effective depth of penetration of the field

  10. Investigation on magnetoacoustic signal generation with magnetic induction and its application to electrical conductivity reconstruction

    Ma Qingyu; He Bin

    2007-01-01

    A theoretical study on the magnetoacoustic signal generation with magnetic induction and its applications to electrical conductivity reconstruction is conducted. An object with a concentric cylindrical geometry is located in a static magnetic field and a pulsed magnetic field. Driven by Lorentz force generated by the static magnetic field, the magnetically induced eddy current produces acoustic vibration and the propagated sound wave is received by a transducer around the object to reconstruct the corresponding electrical conductivity distribution of the object. A theory on the magnetoacoustic waveform generation for a circular symmetric model is provided as a forward problem. The explicit formulae and quantitative algorithm for the electrical conductivity reconstruction are then presented as an inverse problem. Computer simulations were conducted to test the proposed theory and assess the performance of the inverse algorithms for a multi-layer cylindrical model. The present simulation results confirm the validity of the proposed theory and suggest the feasibility of reconstructing electrical conductivity distribution based on the proposed theory on the magnetoacoustic signal generation with magnetic induction

  11. Exploring Fundamental Concepts in Aqueous Solution Conductivity: A General Chemistry Laboratory Exercise

    Nyasulu, Frazier; Stevanov, Kelly; Barlag, Rebecca

    2010-01-01

    Using a conductivity sensor, a temperature sensor, and a datalogger, fundamental factors that affect conductivity are explored. These factors are (i) concentration, (ii) temperature, (iii) ion charge, and (iv) size and or mass of anion. In addition, the conductivities of a number of other solutions are measured. This lab has been designed to…

  12. Incompressible Steady Flow with Tensor Conductivity Leaving a Transverse Magnetic Field

    Witalis, E.A.

    1965-12-01

    The straight channel flow of an inviscid, incompressible fluid with tensor conductivity is considered when the flow leaves a region of constant transverse magnetic field. The channel walls are taken to be insulating, and an eddy current system arises. This is investigated by the method of magnetic field analysis as given by Witalis. The spatial distribution of magnetic field and ohmic power loss, both parallel and transverse to the flow, are given as functions of the Hall parameter with consideration also to the magnetic Reynolds number of the fluid. MHD power generator aspects of this problem and the results are discussed

  13. Incompressible Steady Flow with Tensor Conductivity Leaving a Transverse Magnetic Field

    Witalis, E A

    1965-12-15

    The straight channel flow of an inviscid, incompressible fluid with tensor conductivity is considered when the flow leaves a region of constant transverse magnetic field. The channel walls are taken to be insulating, and an eddy current system arises. This is investigated by the method of magnetic field analysis as given by Witalis. The spatial distribution of magnetic field and ohmic power loss, both parallel and transverse to the flow, are given as functions of the Hall parameter with consideration also to the magnetic Reynolds number of the fluid. MHD power generator aspects of this problem and the results are discussed.

  14. Drag and lift forces between a rotating conductive sphere and a cylindrical magnet

    Nurge, Mark A.; Youngquist, Robert C.; Starr, Stanley O.

    2018-06-01

    Modeling the interaction between a non-uniform magnetic field and a rotating conductive object provides insight into the drag force, which is used in applications such as eddy current braking and linear induction motors, as well as the transition to a repulsive force, which is the basis for magnetic levitation systems. Here, we study the interaction between a non-uniform field generated by a cylindrical magnet and a rotating conductive sphere. Each eddy current in the sphere generates a magnetic field which in turn generates another eddy current, eventually feeding back on itself. A two-step mathematical process is developed to find a closed-form solution in terms of only three eddy currents. However, the complete solution requires decomposition of the magnetic field into a summation of spherical harmonics, making it more suitable for a graduate-level electromagnetism lecture or lab. Finally, the forces associated with these currents are calculated and then verified experimentally.

  15. Drag and Lift Forces Between a Rotating Conductive Sphere and a Cylindrical Magnet

    Nurge, Mark A.; Youngquist, Robert C.

    2017-01-01

    Modeling the interaction between a non-uniform magnetic field and a rotating conductive object allows study of the drag force which is used in applications such as eddy current braking and linear induction motors as well as the transition to a repulsive force that is the basis for magnetic levitation systems. Here, we study the interaction between a non-uniform field generated by a cylindrical magnet and a rotating conductive sphere. Each eddy current in the sphere generates a magnetic field which in turn generates another eddy current, eventually feeding back on itself. A two step mathematics process is developed to find a closed form solution in terms of only two eddy currents. However, the complete solution requires decomposition of the magnetic field into a summation of spherical harmonics, making it more suitable for a graduate level electromagnetism lecture or lab. Finally, the forces associated with these currents are calculated and then verified experimentally.

  16. Ground state magnetization of conduction electrons in graphene with Zeeman effect

    Escudero, F., E-mail: federico.escudero@uns.edu.ar [Departamento de Física, Universidad Nacional del Sur, Av. Alem 1253, B8000CPB Bahía Blanca (Argentina); Instituto de Física del Sur (IFISUR, UNS-CONICET), Av. Alem 1253, B8000CPB Bahía Blanca (Argentina); Ardenghi, J.S., E-mail: jsardenhi@gmail.com [Departamento de Física, Universidad Nacional del Sur, Av. Alem 1253, B8000CPB Bahía Blanca (Argentina); Instituto de Física del Sur (IFISUR, UNS-CONICET), Av. Alem 1253, B8000CPB Bahía Blanca (Argentina); Sourrouille, L., E-mail: lsourrouille@yahoo.es [Departamento de Física, Universidad Nacional del Sur, Av. Alem 1253, B8000CPB Bahía Blanca (Argentina); Instituto de Física del Sur (IFISUR, UNS-CONICET), Av. Alem 1253, B8000CPB Bahía Blanca (Argentina); Jasen, P., E-mail: pvjasen@uns.edu.ar [Departamento de Física, Universidad Nacional del Sur, Av. Alem 1253, B8000CPB Bahía Blanca (Argentina); Instituto de Física del Sur (IFISUR, UNS-CONICET), Av. Alem 1253, B8000CPB Bahía Blanca (Argentina)

    2017-05-01

    In this work we address the ground state magnetization in graphene, considering the Zeeman effect and taking into account the conduction electrons in the long wavelength approximation. We obtain analytical expressions for the magnetization at T=0 K, where the oscillations given by the de Haas van Alphen (dHvA) effect are present. We find that the Zeeman effect modifies the magnetization by introducing new peaks associated with the spin splitting of the Landau levels. These peaks are very small for typical carrier densities in graphene, but become more important for higher densities. The obtained results provide insight of the way in which the Zeeman effect modifies the magnetization, which can be useful to control and manipulate the spin degrees of freedom. - Highlights: • The magnetization has peaks whenever the last energy level changes discontinuously. • The peaks amplitude depends on the electron density. • The Zeeman effect introduces new peaks in the magnetization.

  17. First Ideas Towards the Super-Conducting Magnet Design for the HESR at FAIR

    Eichhorn, Ralf; Gussen, Achim; Martin, Siegfried

    2005-01-01

    The Forschungszentrum Juelich has taken the leadership of a consortium being responsible for the design of the HESR going to be part of the FAIR project at GSI. The HESR is a 50 Tm storage ring for antiprotons, based on a super-conducting magnet technology. On basis of the RHIC Dipole D0 (3.6 T), the magnet design for the HESR has started recently. One key issue will be a very compact layout because of the rather short magnets (been 1.82 m for the dipoles and 0.5 m for the other magnets). This paper will present first ideas of the magnetic and cryogenic layout, give a status report on the achievements so far and discuss the need and possible solutions for a bent magnet with a radius of curvature of 13.2 m.

  18. Study of the conductivity of a metallic tube by analysing the damped fall of a magnet

    Iniguez, J; Raposo, V; Hernandez-Lopez, A; Flores, A G; Zazo, M

    2004-01-01

    The fall of a magnet through a hollow conducting tube is described. Although this experiment is well known, a detailed treatment by means of a circuit analysis allows us to relate the conductivity of the tube to the characteristic parameters of the experiment

  19. Chemistry of paramagnetic and diamagnetic contrast agents for Magnetic Resonance Imaging and Spectroscopy

    Perez-Mayoral, Elena; Negri, Viviana; Soler-Padros, Jordi; Cerdan, Sebastian; Ballesteros, Paloma

    2008-01-01

    We provide a brief overview of the chemistry and most relevant properties of paramagnetic and diamagnetic contrast agents (CAs) for Magnetic Resonance Imaging and Magnetic Resonance Spectroscopic Imaging. Paramagnetic CAs for MRI consist mainly of Gd(III) complexes from linear or macrocyclic polyaminopolycarboxylates. These agents reduce, the relaxation times T 1 and T 2 of the water protons in a concentration dependent manner, increasing selectively MRI contrast in those regions in which they accumulate. In most instances they provide anatomical information on the localization of lesions and in some specific cases they may allow to estimate some physiological properties of tissues including mainly vascular performance. Because of its ability to discriminate easily between normal and diseased tissue, extracellular pH (pH e ) has been added recently, to the battery of variables amenable to MRI investigation. A variety of Gd(III) containing macrocycles sensitive to pH, endogenous or exogenous polypeptides or even liposomes have been investigated for this purpose, using the pH dependence of their relaxivity or magnetization transfer rate constant (chemical exchange saturation transfer, CEST). Many environmental circumstances in addition to pH affect, however, relaxivity or magnetization transfer rate constants of these agents, making the results of pH measurements by MRI difficult to interpret. To overcome these limitations, our laboratory synthesized and developed a novel series of diamagnetic CAs for Magnetic Resonance Spectroscopic Imaging, a new family of monomeric and dimeric imidazolic derivatives able to provide unambiguous measurements of pH e , independent of water relaxivity, diffusion or exchange

  20. Chemistry of paramagnetic and diamagnetic contrast agents for Magnetic Resonance Imaging and Spectroscopy

    Perez-Mayoral, Elena [Laboratorio de Sintesis Organica e Imagen Molecular por Resonancia Magnetica, Facultad de Ciencias, UNED, Paseo Senda del Rey 9, E-28040 Madrid (Spain); Departamento de Quimica Inorganica y Quimica Tecnica, Facultad de Ciencias, UNED, Paseo Senda del Rey 9, E-28040 Madrid (Spain); Negri, Viviana; Soler-Padros, Jordi [Laboratorio de Sintesis Organica e Imagen Molecular por Resonancia Magnetica, Facultad de Ciencias, UNED, Paseo Senda del Rey 9, E-28040 Madrid (Spain); Cerdan, Sebastian [Laboratorio de Imagen Espectroscopica por Resonancia Magnetica (LIERM), Instituto de Investigaciones Biomedicas ' Alberto Sols' , CSIC/UAM, c/Arturo Duperier 4, E-28029 Madrid (Spain); Ballesteros, Paloma [Laboratorio de Sintesis Organica e Imagen Molecular por Resonancia Magnetica, Facultad de Ciencias, UNED, Paseo Senda del Rey 9, E-28040 Madrid (Spain)], E-mail: pballesteros@ccia.uned.es

    2008-09-15

    We provide a brief overview of the chemistry and most relevant properties of paramagnetic and diamagnetic contrast agents (CAs) for Magnetic Resonance Imaging and Magnetic Resonance Spectroscopic Imaging. Paramagnetic CAs for MRI consist mainly of Gd(III) complexes from linear or macrocyclic polyaminopolycarboxylates. These agents reduce, the relaxation times T{sub 1} and T{sub 2} of the water protons in a concentration dependent manner, increasing selectively MRI contrast in those regions in which they accumulate. In most instances they provide anatomical information on the localization of lesions and in some specific cases they may allow to estimate some physiological properties of tissues including mainly vascular performance. Because of its ability to discriminate easily between normal and diseased tissue, extracellular pH (pH{sub e}) has been added recently, to the battery of variables amenable to MRI investigation. A variety of Gd(III) containing macrocycles sensitive to pH, endogenous or exogenous polypeptides or even liposomes have been investigated for this purpose, using the pH dependence of their relaxivity or magnetization transfer rate constant (chemical exchange saturation transfer, CEST). Many environmental circumstances in addition to pH affect, however, relaxivity or magnetization transfer rate constants of these agents, making the results of pH measurements by MRI difficult to interpret. To overcome these limitations, our laboratory synthesized and developed a novel series of diamagnetic CAs for Magnetic Resonance Spectroscopic Imaging, a new family of monomeric and dimeric imidazolic derivatives able to provide unambiguous measurements of pH{sub e}, independent of water relaxivity, diffusion or exchange.

  1. Heat characteristic analysis of a conduction cooling toroidal-type SMES magnet

    Kim, K.M.; Kim, A.R.; Kim, J.G.; Kim, D.W.; Park, M.; Yu, I.K.; Eom, B.Y.; Sim, K.; Kim, S.H.; Shon, M.H.; Kim, H.J.; Bae, H.J.; Seong, K.C.

    2010-01-01

    This paper analyzed the heat characteristics of a conduction cooling toroidal-type SMES magnet. The authors designed and manufactured a conduction cooling toroidal-type SMES magnet which consists of 30 double pancake coils. One (a single pancake coil) of a double pancake coil is arranged at an angle of 6 o from each other. The shape of the toroidal-type SMES magnet was designed by a 3D CAD program. The heat invasion was investigated under no-load condition and the thermal characteristic of the toroidal-type SMES magnet was analyzed using the Finite Elements Method program. Both the analyzed and the experiment results are compared and discussed in detail.

  2. A Conduction-Cooled Superconducting Magnet System-Design, Fabrication and Thermal Tests

    Song, Xiaowei (Andy); Holbøll, Joachim; Wang, Qiuliang

    2015-01-01

    A conduction-cooled superconducting magnet system with an operating current of 105.5 A was designed, fabricated and tested for material processing applications. The magnet consists of two coaxial NbTi solenoid coils with an identical vertical height of 300 mm and is installed in a high-vacuumed c......A conduction-cooled superconducting magnet system with an operating current of 105.5 A was designed, fabricated and tested for material processing applications. The magnet consists of two coaxial NbTi solenoid coils with an identical vertical height of 300 mm and is installed in a high......-vacuumed cryostat. A two-stage GM cryocooler with a cooling power of 1.5 W at 4.2 K in the second stage is used to cool the system from room temperature to 4.2 K. In this paper, the detailed design, fabrication, thermal analysis and tests of the system are presented....

  3. Magnet/cryocooler integration for thermal stability in conduction-cooled systems

    Chang, H.-M.; Kwon, K. B.

    2002-05-01

    The stability conditions that take into accounts the size of superconducting magnets and the refrigeration capacity of cryocoolers are investigated for the conduction-cooled systems without liquid cryogens. The worst scenario in the superconducting systems is that the heat generation in the resistive state exceeds the refrigeration, causing a rise in the temperature of the magnet winding and leading to burnout. It is shown by an analytical solution that in the continuously resistive state, the temperature may increase indefinitely or a stable steady state may be reached, depending upon the relative size of the magnet with respect to the refrigeration capacity of the cryocooler. The stability criteria include the temperature-dependent properties of the magnet materials and the refrigeration characteristics of the cryocooler. A useful graphical scheme is presented and the design of the stable magnet/cryocooler interface is demonstrated.

  4. Structural vs. intrinsic carriers: contrasting effects of cation chemistry and disorder on ionic conductivity in pyrochlores

    Perriot, Romain; Uberuaga, Blas P.

    2015-01-01

    We use molecular dynamics simulations to investigate the role of cation disorder on oxygen diffusion in Gd 2 Zr 2 O 7 (GZO) and Gd 2 Ti 2 O 7 (GTO) pyrochlores, a class of complex oxides which contain a structural vacancy relative to the basic fluorite structure. The introduction of disorder has distinct effects depending on the chemistry of the material, increasing the mobility of structural carriers by up to four orders of magnitude in GZO. In contrast, in GTO, there is no mobility at zero or low disorder on the ns timescale, but higher disorder liberates the otherwise immobile carriers, allowing diffusion with rates comparable to GZO for the fully disordered material. Here, we show that the cation disorder enhances the diffusivity by both increasing the concentration of mobile structural carriers and their individual mobility. The disorder also influences the diffusion in materials containing intrinsic carriers, such as additional vacancies VO or oxygen interstitials OI. And while in ordered GZO and GTO the contribution of the intrinsic carriers dominates the overall diffusion of oxygen, OI in GZO contributes along with structural carriers, and the total diffusion rate can be calculated by assuming simple additive contributions from the two sources. Although the disorder in the materials with intrinsic defects usually enhances the diffusivity as in the defect-free case, in low concentrations, cation antisites AB or BA, where A = Gd and B = Zr or Ti, can act as traps for fast intrinsic defects. The trapping results in a lowering of the diffusivity, and causes a non-monotonic behavior of the diffusivity with disorder. Conversely, in the case of slow intrinsic defects, the main effect of the disorder is to liberate the structural carriers, resulting in an increase of the diffusivity regardless of the defect trapping.

  5. Effect of a gap opening on the conductance of graphene with magnetic barrier structures

    Esmailpour, Mohammad

    2018-04-01

    In the present study Klein tunneling in a single-layer gapped graphene was investigated by transfer matrix method under normal magnetic field for one and two magnetic barriers. Calculations show that electron transmission through a magnetic barrier is deflected to positive angles and reduces as the magnitude of magnetic field and especially the energy gap increases. This reduction is even more significant in larger fields so that after reaching a specific value of energy gap, an effective confinement for fermions and suppression of Klein tunneling is reached particularly in normal incidence and the conductance becomes zero. Unlike one barrier, the process of tunneling through two magnetic barriers induces symmetric transmission probability versus the incident angle; even, for lower energy gaps, electron transmission probability increases which in turn reduces total conductance via proper changes in the value of the magnetic field and energy gap. In general, it is concluded that confining electrons in asymmetric transmission through one barrier is conducted better than two barriers.

  6. SNS Resonance Control Cooling Systems and Quadrupole Magnet Cooling Systems DIW Chemistry

    Magda, Karoly [ORNL

    2018-01-01

    This report focuses on control of the water chemistry for the Spallation Neutron Source (SNS) Resonance Control Cooling System (RCCS)/Quadrupole Magnet Cooling System (QMCS) deionized water (DIW) cooling loops. Data collected from spring 2013 through spring 2016 are discussed, and an operations regime is recommended.It was found that the RCCS operates with an average pH of 7.24 for all lines (from 7.0 to 7.5, slightly alkaline), the average low dissolved oxygen is in the area of < 36 ppb, and the main loop average resistivity of is > 14 MΩ-cm. The QMCS was found to be operating in a similar regime, with a slightly alkaline pH of 7.5 , low dissolved oxygen in the area of < 45 ppb, and main loop resistivity of 10 to 15 MΩ-cm. During data reading, operational corrections were done on the polishing loops to improve the water chemistry regime. Therefore some trends changed over time.It is recommended that the cooling loops operate in a regime in which the water has a resistivity that is as high as achievable, a dissolved oxygen concentration that is as low as achievable, and a neutral or slightly alkaline pH.

  7. Structure, Raman spectra and defect chemistry modelling of conductive pyrochlore oxides

    Poulsen, F.W.; Glerup, M.; Holtappels, P.

    2000-01-01

    -O(x) and V-O on the O site, interstitial oxygens O-i", and delocalised electrons and electron holes. Four mass action law expressions govern such a model. The defect model can rationalise why home-valent doping, i.e. substitution of Zr(4+) by Ce(4+), can lead to an increase in ionic conductivity...

  8. Theoretical study of optical conductivity of graphene with magnetic and nonmagnetic adatoms

    Majidi, Muhammad Aziz; Siregar, Syahril; Rusydi, Andrivo

    2014-11-01

    We present a theoretical study of the optical conductivity of graphene with magnetic and nonmagnetic adatoms. First, by introducing an alternating potential in a pure graphene, we demonstrate a gap formation in the density of states and the corresponding optical conductivity. We highlight the distinction between such a gap formation and the so-called Pauli blocking effect. Next, we apply this idea to graphene with adatoms by introducing magnetic interactions between the carrier spins and the spins of the adatoms. Exploring various possible ground-state spin configurations of the adatoms, we find that the antiferromagnetic configuration yields the lowest total electronic energy and is the only configuration that forms a gap. Furthermore, we analyze four different circumstances leading to similar gaplike structures and propose a means to interpret the magneticity and the possible orderings of the adatoms on graphene solely from the optical conductivity data. We apply this analysis to the recently reported experimental data of oxygenated graphene.

  9. Conductivity enhancement induced by casting of polymer electrolytes under a magnetic field

    Kovarsky, R.; Golodnitsky, D.; Peled, E.; Khatun, S.; Stallworth, P.E.; Greenbaum, S.; Greenbaum, A.

    2011-01-01

    Highlights: ► Ordering of polymer electrolytes under applied magnetic field. ► Positive effect of nanosize ferromagnetic filler. ► Structure-ion conductivity interrelationship. - Abstract: We recently presented a procedure for orienting the polyethylene-oxide (PEO) helices in a direction perpendicular to the film plane by casting the polymer electrolytes (PE) under a magnetic field (MF). Here we study the influence of magnetic fields of different strengths and configurations on the structural properties and ionic conductivity of concentrated LiCF 3 SO 3 (LiTf) and LiAsF 6 :P(EO) pristine and composite polymer electrolytes containing γ-Fe 2 O 3 nanoparticles. Some data of LiI:P(EO) system are shown for comparison. We suggest that the effect of type of salt (LiI, LiTf and LiAsF 6 ) on the structure–conductivity relationship of the polymer electrolytes cast under magnetic field is closely connected to the crystallinity of the PEO–LiX system. It was found that the higher the content of the crystalline phase and the size of spherulites in the typically cast salt-polymer system, the stronger the influence of the magnetic field on the conductivity enhancement when the electrolyte is cast and dried under MF. Casting of the PE from a high-dielectric-constant solvent results in disentanglement of the PEO chains, which facilitates even more the perpendicular orientation of helices under applied MF. The enhancement of ionic conductivity was appreciably higher in the PEs cast under strong NdFeB magnets than under SmCo. Both bulk (intrachain) and grain-boundary conductivities increase when a MF is applied, but the improvement in the grain-boundary conductivity – associated with ion-hopping between polymer chains – is more pronounced. For LiAsF 6 :(PEO) 3 at 65 °C, the interchain conductivity increased by a factor of 75, while the intrachain conductivity increased by a factor of 11–14. At room temperature, the SEI resistance of these PEs, cast under NdFeB HMF

  10. Influence of disorder and magnetic field on conductance of “sandwich” type two dimensional system

    Long LIU

    2017-04-01

    Full Text Available In order to discuss the transport phenomena and the physical properties of the doping of the disorder system under magnetic field, the electron transport in a two-dimensional system is studied by using Green function and scattering matrix theory. Base on the two-dimensional lattice model, the phenomenon of quantized conductance of the "sandwich" type electronic system is analyzed. The contact between the lead and the scatterer reduce the system's conductance, and whittle down the quantum conductance stair-stepping phenomenon; when an external magnetic field acts on to the system, the conductance presents a periodicity oscillation with the magnetic field. The intensity of this oscillation is related to the energy of the electron;with the increase of the impurity concentration, the conductance decreases.In some special doping concentration, the conductance of the system can reach the ideal step value corresponding to some special electron energy. The result could provide reference for further study of the conductance of the "sandwich" type two dimensional system.

  11. Synthesis, properties, and application in peptide chemistry of a magnetically separable and reusable biocatalyst

    Liria, Cleber W.; Ungaro, Vitor A.; Fernandes, Raphaella M.; Costa, Natália J. S.; Marana, Sandro R.; Rossi, Liane M.; Machini, M. Teresa

    2014-11-01

    Enzyme-catalyzed chemical processes are selective, very productive, and generate little waste. Nevertheless, they may be optimized using enzymes bound to solid supports, which are particularly important for protease-mediated reactions since proteases undergo fast autolysis in solution. Magnetic nanoparticles are suitable supports for this purpose owing to their high specific surface area and to be easily separated from reaction media. Here we describe the immobilization of bovine α-chymotrypsin (αCT) on silica-coated superparamagnetic nanoparticles (Fe3O4@silica) and the characterization of the enzyme-nanoparticle hybrid (Fe3O4@silica-αCT) in terms of protein content, properties, recovery from reaction media, application, and reuse in enzyme-catalyzed peptide synthesis. The results revealed that (i) full acid hydrolysis of the immobilized protease followed by amino acid analysis of the hydrolyzate is a reliable method to determine immobilization yield; (ii) despite showing lower amidase activity and a lower K cat/ K m value for a specific substrate than free αCT, the immobilized enzyme is chemically and thermally more stable, magnetically recoverable from reaction media, and can be consecutively reused for ten cycles to catalyze the amide bond hydrolysis and ester hydrolysis of the protected dipeptide Z-Ala-Phe-OMe. Altogether, these properties indicate the potential of Fe3O4@silica-αCT to act as an efficient, suitably stable, and reusable catalyst in amino acid, peptide, and protein chemistry as well as in proteomic studies.

  12. Particle precipitation influence in the conductivity of the auroral ionosphere during magnetic storms

    Monreal M, R.; Llop, C.

    2002-01-01

    The study of the energy transfer between the different regions of the solar wind - magnetosphere - ionosphere system is probably the main goal in Solar-Terrestrial Physics. In the magnetosphere - ionosphere coupling, the ionosphere power dissipation is highly sensitive to the conductivity in such a way that a detailed knowledge of this property in the auroral and polar ionosphere is of great interest because it is important not only to determine Joule heat, but also for electric fields and currents models including the field aligned currents coupling the magnetosphere and ionosphere. The main sources of ionization and subsequent conductivity in the ionosphere are due to the emission of electromagnetic radiation and charged energetic particles from the sun. In this work it is analysed the influence of the precipitating electrons on the auroral ionosphere conductivity during magnetic storms. It is shown that the conductance values appear sub estimated for high levels of activity due to the saturation produced during very intense magnetic storms. (Author)

  13. Calculation of electromagnetic constitutive parameters of insulating magnetic materials with conducting inclusions

    Kuster, E.; Moore, R.; Lust, L.; Kemper, P. [Georgia Inst. of Tech., Atlanta, GA (United States)

    1996-12-31

    A Method of Moments (MoM) electromagnetic model of percolating conducting films was applied to calculate the effective parameters of the composite formed by conducting inclusions placed within a dispersive magnetic but nondispersive dielectric matrix. The MoM calculations demonstrate a coupling between the magnetic properties of the matrix and the effective composite permittivity and frequency dispersion of the composite. The coupling of permittivity and permeability is observed near the percolation threshold of the composite and for high conductivity inclusions. The prediction agrees with physical expectations since near percolation the conduction correlation length dominates the effective permittivity of the composite and this correlation length is determined by both the permittivity and permeability of the composite.

  14. Thermal conductivity of a quantum spin-1/2 antiferromagnetic chain with magnetic impurities

    Zviagin, A.A.

    2008-01-01

    We present an exact theory that describes how magnetic impurities change the behavior of the thermal conductivity for the integrable Heisenberg antiferromagnetic quantum spin-1/2 chain. Single magnetic impurities and a large concentration of impurities with similar values of the couplings to the host chain (a weak disorder) do not change the linear-in-temperature low-T behavior of the thermal conductivity: Only the slope of that behavior becomes smaller, compared to the homogeneous case. The strong disorder in the distribution of the impurity-host couplings produces more rapid temperature growth of the thermal conductivity, compared to the linear-in-T dependence of the homogeneous chain and the chain with weak disorder. Recent experiments on the thermal conductivity in inhomogeneous quasi-one-dimensional quantum spin systems manifest qualitative agreement with our results

  15. Magnetic-field-controlled negative differential conductance in scanning tunneling spectroscopy of graphene npn junction resonators

    Li, Si-Yu; Liu, Haiwen; Qiao, Jia-Bin; Jiang, Hua; He, Lin

    2018-03-01

    Negative differential conductance (NDC), characterized by the decreasing current with increasing voltage, has attracted continuous attention for its various novel applications. The NDC typically exists in a certain range of bias voltages for a selected system and controlling the regions of NDC in curves of current versus voltage (I -V ) is experimentally challenging. Here, we demonstrate a magnetic-field-controlled NDC in scanning tunneling spectroscopy of graphene npn junction resonators. The magnetic field not only can switch on and off the NDC, but also can continuously tune the regions of the NDC in the I -V curves. In the graphene npn junction resonators, magnetic fields generate sharp and pronounced Landau-level peaks with the help of the Klein tunneling of massless Dirac fermions. A tip of scanning tunneling microscope induces a relatively shift of the Landau levels in graphene beneath the tip. Tunneling between the misaligned Landau levels results in the magnetic-field-controlled NDC.

  16. The effect of magnetic mirror on near wall conductivity in Hall thrusters

    Yu, D.; Liu, H.; Fu, H.; Cao, Y.

    2008-01-01

    The effect of magnetic mirror on near wall conductivity is studied in the acceleration region of Hall thrusters. The electron dynamics process in the plasma is described by test particle method, in which electrons are randomly emitted from the centerline towards the inner wall of the channel. It is found that the effective collision coefficient, i.e. the rate of electrons colliding with the wall, changes dramatically with the magnetic mirror effect being considered; and that it decreases further with the increase of magnetic mirror ratio to enhance the electron mobility accordingly. In particular, under anistropic electron velocity distribution conditions, the magnetic mirror effect becomes even more prominent. Furthermore, due to decrease in magnetic mirror ratio from the exhaust plane to the anode in Hall thrusters, the axial gradient of electron mobility with magnetic mirror effect is greater than without it. The magnetic mirror effects on electron mobility are derived analytically and the results are found in agreement with the simulation. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. The Effect of a Spiral Gradient Magnetic Field on the Ionic Conductivity of Water

    Bartušek, Karel; Marcon, P.; Fiala, P.; Máca, J.; Dohnal, P.

    2017-01-01

    Roč. 9, č. 9 (2017), s. 1-8, č. článku 664. ISSN 2073-4441 R&D Projects: GA ČR(CZ) GA17-00607S Institutional support: RVO:68081731 Keywords : gradient field * demineralized water * conductivity * ionic conductivity * magnetic field Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis) Impact factor: 1.832, year: 2016

  18. Combined centroid-envelope dynamics of intense, magnetically focused charged beams surrounded by conducting walls

    Fiuza, K.; Rizzato, F.B.; Pakter, R.

    2006-01-01

    In this paper we analyze the combined envelope-centroid dynamics of magnetically focused high-intensity charged beams surrounded by conducting walls. Similar to the case where conducting walls are absent, it is shown that the envelope and centroid dynamics decouple from each other. Mismatched envelopes still decay into equilibrium with simultaneous emittance growth, but the centroid keeps oscillating with no appreciable energy loss. Some estimates are performed to analytically obtain characteristics of halo formation seen in the full simulations

  19. Thermal conductivity of magnetic insulators with strong spin-orbit coupling

    Stamokostas, Georgios; Lapas, Panteleimon; Fiete, Gregory A.

    We study the influence of spin-orbit coupling on the thermal conductivity of various types of magnetic insulators. In the absence of spin-orbit coupling and orbital-degeneracy, the strong-coupling limit of Hubbard interactions at half filling can often be adequately described in terms of a pure spin Hamiltonian of the Heisenberg form. However, in the presence of spin-orbit coupling the resulting exchange interaction can become highly anisotropic. The effect of the atomic spin-orbit coupling, taken into account through the effect of magnon-phonon interactions and the magnetic order and excitations, on the lattice thermal conductivity of various insulating magnetic systems is studied. We focus on the regime of low temperatures where the dominant source of scattering is two-magnon scattering to one-phonon processes. The thermal current is calculated within the Boltzmann transport theory. We are grateful for financial support from NSF Grant DMR-0955778.

  20. Conductance oscillations of core-shell nanowires in transversal magnetic fields

    Manolescu, Andrei; Nemnes, George Alexandru; Sitek, Anna; Rosdahl, Tomas Orn; Erlingsson, Sigurdur Ingi; Gudmundsson, Vidar

    2016-05-01

    We analyze theoretically electronic transport through a core-shell nanowire in the presence of a transversal magnetic field. We calculate the conductance for a variable coupling between the nanowire and the attached leads and show how the snaking states, which are low-energy states localized along the lines of the vanishing radial component of the magnetic field, manifest their existence. In the strong-coupling regime they induce flux periodic, Aharonov-Bohm-like, conductance oscillations, which, by decreasing the coupling to the leads, evolve into well-resolved peaks. The flux periodic oscillations arise due to interference of the snaking states, which is a consequence of backscattering at either the contacts with leads or magnetic or potential barriers in the wire.

  1. On averaging the Kubo-Hall conductivity of magnetic Bloch bands leading to Chern numbers

    Riess, J.

    1997-01-01

    The authors re-examine the topological approach to the integer quantum Hall effect in its original form where an average of the Kubo-Hall conductivity of a magnetic Bloch band has been considered. For the precise definition of this average it is crucial to make a sharp distinction between the discrete Bloch wave numbers k 1 , k 2 and the two continuous integration parameters α 1 , α 2 . The average over the parameter domain 0 ≤ α j 1 , k 2 . They show how this can be transformed into a single integral over the continuous magnetic Brillouin zone 0 ≤ α j j , j = 1, 2, n j = number of unit cells in j-direction, keeping k 1 , k 2 fixed. This average prescription for the Hall conductivity of a magnetic Bloch band is exactly the same as the one used for a many-body system in the presence of disorder

  2. Methods of Using a Magnetic Field Response Sensor Within Closed, Electrically Conductive Containers

    Woodward, Stanley E.; Taylor, Bryant D.

    2010-01-01

    Magnetic field response sensors are a class of sensors that are powered via oscillating magnetic fields, and when electrically active, respond with their own magnetic fields with attributes dependent upon the magnitude of the physical quantity being measured. A magnetic field response recorder powers and interrogates the magnetic sensors [see Magnetic-Field-Response Measurement- Acquisition System, NASA Tech Briefs Vol. 30, No, 6 (June 2006, page 28)]. Electrically conductive containers have low transmissivity for radio frequency (RF) energy and thus present problems for magnetic field response sensors. It is necessary in some applications to have a magnetic field response sensor s capacitor placed in these containers. Proximity to conductive surfaces alters the inductance and capacitance of the sensors. As the sensor gets closer to a conductive surface, the electric field and magnetic field energy of the sensor is reduced due to eddy currents being induced in the conductive surface. Therefore, the capacitors and inductors cannot be affixed to a conductive surface or embedded in a conductive material. It is necessary to have a fixed separation away from the conductive material. The minimum distance for separation is determined by the desired sensor response signal to noise ratio. Although the inductance is less than what it would be if it were not in proximity to the conductive surface, the inductance is fixed. As long as the inductance is fixed, all variations of the magnetic field response are due to capacitance changes. Numerous variations of inductor mounting can be utilized, such as providing a housing that provides separation from the conductive material as well as protection from impact damage. The sensor can be on the same flexible substrate with a narrow throat portion of the sensor between the inductor and the capacitor, Figure 1. The throat is of sufficient length to allow the capacitor to be appropriately placed within the container and the inductor

  3. Acoustic Source Analysis of Magnetoacoustic Tomography With Magnetic Induction for Conductivity Gradual-Varying Tissues.

    Wang, Jiawei; Zhou, Yuqi; Sun, Xiaodong; Ma, Qingyu; Zhang, Dong

    2016-04-01

    As a multiphysics imaging approach, magnetoacoustic tomography with magnetic induction (MAT-MI) works on the physical mechanism of magnetic excitation, acoustic vibration, and transmission. Based on the theoretical analysis of the source vibration, numerical studies are conducted to simulate the pathological changes of tissues for a single-layer cylindrical conductivity gradual-varying model and estimate the strengths of sources inside the model. The results suggest that the inner source is generated by the product of the conductivity and the curl of the induced electric intensity inside conductivity homogeneous medium, while the boundary source is produced by the cross product of the gradient of conductivity and the induced electric intensity at conductivity boundary. For a biological tissue with low conductivity, the strength of boundary source is much higher than that of the inner source only when the size of conductivity transition zone is small. In this case, the tissue can be treated as a conductivity abrupt-varying model, ignoring the influence of inner source. Otherwise, the contributions of inner and boundary sources should be evaluated together quantitatively. This study provide basis for further study of precise image reconstruction of MAT-MI for pathological tissues.

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

    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

  5. On Electromagnetic Modulation of Flow Instabilities, Mixing and Heat Transfer in Conducting and Magnetized Fluids

    Kenjeres, S.

    2016-01-01

    In the present paper we give a concise review of some recent highlights of our research dealing with electromagnetic control of flow, mixing and heat transfer of electrically conductive or magnetized fluids. We apply a combination of state-of-art numerical (DNS and LES) and experimental (PIV and

  6. Functional Assessment of Corticospinal Conduction with Transcranial Magnetic Stimulation: Basic Principles

    Groppa, S.; Peller, M.; Siebner, Hartwig R.

    2010-01-01

    Here we review how transcranial magnetic stimulation (TMS) is used in clinical practice to examine the functional integrity of the fast conducting fibres of the human corticomotor path ways. We first summarise the technical and physiological principles of TMS that are relevant to its clinical use...

  7. Survey of Processing Methods for High Strength High Conductivity Wires for High Field Magnet Applications

    Han, K.; Embury, J.D.

    1998-10-01

    This paper will deal with the basic concepts of attaining combination of high strength and high conductivity in pure materials, in-situ composites and macrocomposites. It will survey current attainments, and outline where some future developments may lie in developing wire products that are close to the theoretical strength of future magnet applications.

  8. Magnetic Field of Conductive Objects as Superposition of Elementary Eddy Currents and Eddy Current Tomography

    Sukhanov, D. Ya.; Zav'yalova, K. V.

    2018-03-01

    The paper represents induced currents in an electrically conductive object as a totality of elementary eddy currents. The proposed scanning method includes measurements of only one component of the secondary magnetic field. Reconstruction of the current distribution is performed by deconvolution with regularization. Numerical modeling supported by the field experiments show that this approach is of direct practical relevance.

  9. A polarity-induced defect mechanism for conductivity and magnetism at polar-nonpolar oxide interfaces.

    Yu, Liping; Zunger, Alex

    2014-10-13

    The discovery of conductivity and magnetism at the polar-nonpolar interfaces of insulating nonmagnetic oxides such as LaAlO3 and SrTiO3 has raised prospects for attaining interfacial functionalities absent in the component materials. Yet, the microscopic origin of such emergent phenomena remains unclear, posing obstacles to design of improved functionalities. Here we present first principles calculations of electronic and defect properties of LaAlO3/SrTiO3 interfaces and reveal a unifying mechanism for the origins of both conductivity and magnetism. We demonstrate that the polar discontinuity across the interface triggers thermodynamically the spontaneous formation of certain defects that in turn cancel the polar field induced by the polar discontinuity. The ionization of the spontaneously formed surface oxygen vacancy defects leads to interface conductivity, whereas the unionized Ti-on-Al antisite defects lead to interface magnetism. The proposed mechanism suggests practical design principles for inducing and controlling both conductivity and magnetism at general polar-nonpolar interfaces.

  10. Survey of Processing Methods for High Strength High Conductivity Wires for High Field Magnet Applications

    Han, K.; Embury, J.D.

    1998-01-01

    This paper will deal with the basic concepts of attaining combination of high strength and high conductivity in pure materials, in-situ composites and macrocomposites. It will survey current attainments, and outline where some future developments may lie in developing wire products that are close to the theoretical strength of future magnet applications

  11. Magnetic hyaluronic acid nanospheres via aqueous Diels-Alder chemistry to deliver dexamethasone for adipose tissue engineering.

    Jia, Yang; Fan, Ming; Chen, Huinan; Miao, Yuting; Xing, Lian; Jiang, Bohong; Cheng, Qifan; Liu, Dongwei; Bao, Weikang; Qian, Bin; Wang, Jionglu; Xing, Xiaodong; Tan, Huaping; Ling, Zhonghua; Chen, Yong

    2015-11-15

    Biopolymer-based nanospheres have great potential in the field of drug delivery and tissue regenerative medicine. In this work, we present a flexible way to conjugate a magnetic hyaluronic acid (HA) nanosphere system that are capable of vectoring delivery of adipogenic factor, e.g. dexamethasone, for adipose tissue engineering. Conjugation of nanospheres was established by aqueous Diels-Alder chemistry between furan and maleimide of HA derivatives. Simultaneously, a furan functionalized dexamethasone peptide, GQPGK, was synthesized and covalently immobilized into the nanospheres. The magnetic HA nanospheres were fabricated by encapsulating super-paramagnetic iron oxide nanoparticles, which exhibited quick magnetic sensitivity. The aqueous Diels-Alder chemistry made nanospheres high binding efficiency of dexamethasone, and the vectoring delivery of dexamethasone could be easily controlled by a external magnetic field. The potential application of the magnetic HA nanospheres on vectoring delivery of adipogenic factor was confirmed by co-culture of human adipose-derived stem cells (ASCs). In vitro cytotoxicity tests demonstrated that incorporation of dexamethasone into magnetic HA nanospheres showed high efficiency to promote ASCs viabilities, in particular under a magnetic field, which suggested a promising future for adipose regeneration applications. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Study on a Haptic Sensor Using MCF (Magnetic Compound Fluid) Electric Conductive Rubber

    Zheng, Yaoyang; Shimada, Kunio

    To provide a new composite material having a high degree of sensitivity regarding both electrical conduction and temperature for the field of robotics or sensing, we have developed magnetic rubber that contains a network-like magnetic cluster. We compared the temperature response of MCF rubber with others rubbers made under various experimental conditions, allowing us to find an optimum condition for making MCF rubber. The temperature response was obtained by an experimental equation. We also compared the electric conductivity of MCF rubber with that of ordinary electric conductive rubber and found that its electric sensitivity was lower at a small deformation, but increased at larger deformations. Therefore, MCF rubber has proven itself effective as a switching sensor when a small deformation is applied.

  13. Edge magnetism impact on electrical conductance and thermoelectric properties of graphenelike nanoribbons

    Krompiewski, Stefan; Cuniberti, Gianaurelio

    2017-10-01

    Edge states in narrow quasi-two-dimensional nanostructures determine, to a large extent, their electric, thermoelectric, and magnetic properties. Nonmagnetic edge states may quite often lead to topological-insulator-type behavior. However, another scenario develops when the zigzag edges are magnetic and the time reversal symmetry is broken. In this work we report on the electronic band structure modifications, electrical conductance, and thermoelectric properties of narrow zigzag nanoribbons with spontaneously magnetized edges. Theoretical studies based on the Kane-Mele-Hubbard tight-binding model show that for silicene, germanene, and stanene both the Seebeck coefficient and the thermoelectric power factor are strongly enhanced for energies close to the charge neutrality point. A perpendicular gate voltage lifts the spin degeneracy of energy bands in the ground state with antiparallel magnetized zigzag edges and makes the electrical conductance significantly spin polarized. Simultaneously the gate voltage worsens the thermoelectric performance. Estimated room-temperature figures of merit for the aforementioned nanoribbons can exceed a value of 3 if phonon thermal conductances are adequately reduced.

  14. The effect of electron thermal conduction on plasma pressure gradient during reconnection of magnetic field lines

    Chu, T.K.

    1987-12-01

    The interplay of electron cross-field thermal conduction and the reconnection of magnetic field lines around an m = 1 magnetic island prior to a sawtooth crash can generate a large pressure gradient in a boundary layer adjacent to the reconnecting surface, leading to an enhanced gradient of poloidal beta to satisfy the threshold condition for ideal MHD modes. This narrow boundary layer and the short onset time of a sawtooth crash can be supported by fine-grained turbulent processes in a tokamak plasma. 11 refs

  15. Defect Chemistry and Electrical Conductivity of Sm-Doped La1-xSrxCoO3-δ for Solid Oxide Fuel Cells

    Björketun, Mårten; Castelli, Ivano Eligio; Rossmeisl, Jan

    2017-01-01

    We have calculated the electrical conductivity of the solid oxide fuel cell (SOFC) cathode contact material La1-xSrxCoO3-δ at 900 K. Experimental trends in conductivity against x, and against δ for fixed x, are correctly reproduced for x ≲ 0.8. Furthermore, we have studied the chemistry of neutral...

  16. The influence of the solid thermal conductivity on active magnetic regenerators

    Nielsen, Kaspar Kirstein; Engelbrecht, Kurt

    2012-01-01

    The influence of the thermal conductivity of the regenerator solid on the performance of a flat plate active magnetic regenerator (AMR) is investigated using an established numerical AMR model. The cooling power at different (fixed) temperature spans is used as a measure of the performance...... for a range of thermal conductivities, operating frequencies, a long and short regenerator, and finally a regenerator with a low and a high number of transfer units (NTU) regenerator. In this way the performance is mapped out and the impact of the thermal conductivity of the solid is probed. Modeling shows...... that under certain operating conditions, the AMR cycle is sensitive to the solid conductivity. It is found that as the operating frequency is increased it is not only sufficient to have a high NTU regenerator but the regenerator performance will also benefit from increased thermal conductivity in the solid...

  17. Magnetic resonance electrical impedance tomography (MREIT): conductivity and current density imaging

    Seo, Jin Keun; Kwon, Ohin; Woo, Eung Je

    2005-01-01

    This paper reviews the latest impedance imaging technique called Magnetic Resonance Electrical Impedance Tomography (MREIT) providing information on electrical conductivity and current density distributions inside an electrically conducting domain such as the human body. The motivation for this research is explained by discussing conductivity changes related with physiological and pathological events, electromagnetic source imaging and electromagnetic stimulations. We briefly summarize the related technique of Electrical Impedance Tomography (EIT) that deals with cross-sectional image reconstructions of conductivity distributions from boundary measurements of current-voltage data. Noting that EIT suffers from the ill-posed nature of the corresponding inverse problem, we introduce MREIT as a new conductivity imaging modality providing images with better spatial resolution and accuracy. MREIT utilizes internal information on the induced magnetic field in addition to the boundary current-voltage measurements to produce three-dimensional images of conductivity and current density distributions. Mathematical theory, algorithms, and experimental methods of current MREIT research are described. With numerous potential applications in mind, future research directions in MREIT are proposed

  18. On Electromagnetic Modulation of Flow Instabilities, Mixing and Heat Transfer in Conducting and Magnetized Fluids

    Kenjeres, S.

    2016-09-01

    In the present paper we give a concise review of some recent highlights of our research dealing with electromagnetic control of flow, mixing and heat transfer of electrically conductive or magnetized fluids. We apply a combination of state-of-art numerical (DNS and LES) and experimental (PIV and LIF) techniques to provide fundamental insights into the complex phenomena of interactions between imposed (or induced) electromagnetic fields and underlying fluid flow. Our analysis covers an extensive range of working fluids, i.e. weakly- and highly-electrically-conductive, as well as magnetized fluids. These interactions are defined through the presence of different types of body forces acting per volume of fluid. A fully closed system of governing equations containing an extended set of the Navier-Stokes and a simplified set of the Maxwell equations is presented. The four characteristic examples are selected: the electromagnetic control of self-sustained jet oscillations, the electromagnetic enhancement of heat transfer in thermal convection, the wake interactions behind magnetic obstacles and finally, the thermo-magnetic convection in differentially heated cubical enclosure. The comparative assessment between experimental and numerical results is presented. It is concluded that generally good agreement between simulations and experiments is obtained for all cases considered, proving the concept of electromagnetic modulation, which can be used in numerous technological applications.

  19. Investigation of film flow of a conducting fluid in a transverse magnetic field, (1)

    Oshima, Shuzo; Yamane, Ryuichiro; Mochimaru, Yoshihiro; Sudo, Kouzo.

    1985-01-01

    Accompanying the development of large electromagnetic pumps transporting liquid metals used as the heat transfer media for nuclear power plants and the electromagnetic flow meters of large capacity, many researches have been carried out on the flow of liquid metals under the action of magnetic field. The utilization of electromagnetic force for continuous casting facilities seems very effective for the total processes from refining to solidification. Hereafter, it will be a technologically important problem to clarify the behavior of electro-conductive fluid with free surface under the action of magnetic field concerning the non-contact control of the interface form of molten metals as well as the cooling problem in nuclear fusion reactors. In this study, first the flow phenomena of MHD liquid film flow in a magnetic field with intensity gradient was analytically examined, and the effect of magnetic field gradient exerted on liquid film thickness and liquid surface form was clarified. Next, the experiment using mercury was carried out. For liquid film flow, magnetic field gradient acted as a kind of non-contact weir. (Kako, I.)

  20. Oscillations of a spring-magnet system damped by a conductive plate

    Ladera, C. L.; Donoso, G.

    2013-09-01

    We study the motion of a spring-magnet system that oscillates with very low frequencies above a circular horizontal non-magnetizable conductive plate. The magnet oscillations couple with the plate via the Foucault currents induced therein. We develop a simple theoretical model for this magneto-mechanical oscillator, a model that leads to the equation of a damped harmonic oscillator, whose weak attenuation constant depends upon the system parameters, e.g. the electrical conductivity of the constituent material of the plate and its thickness. We present a set of validating experiments, the results of which are predicted with good accuracy by our analytical model. Additional experiments can be performed with this oscillating system or its variants. This oscillator is simple and low-cost, easy to assemble, and can be used in experiments or project works in physics teaching laboratories at the undergraduate level.

  1. Oscillations of a spring–magnet system damped by a conductive plate

    Ladera, C L; Donoso, G

    2013-01-01

    We study the motion of a spring–magnet system that oscillates with very low frequencies above a circular horizontal non-magnetizable conductive plate. The magnet oscillations couple with the plate via the Foucault currents induced therein. We develop a simple theoretical model for this magneto-mechanical oscillator, a model that leads to the equation of a damped harmonic oscillator, whose weak attenuation constant depends upon the system parameters, e.g. the electrical conductivity of the constituent material of the plate and its thickness. We present a set of validating experiments, the results of which are predicted with good accuracy by our analytical model. Additional experiments can be performed with this oscillating system or its variants. This oscillator is simple and low-cost, easy to assemble, and can be used in experiments or project works in physics teaching laboratories at the undergraduate level. (paper)

  2. Spin-dependent tunneling conductance in 2D structures in zero magnetic field

    Rozhansky, I.V.; Averkiev, N.S.

    2009-01-01

    The influence of the spin-orbit interaction on the tunneling between two-dimensional electron layers is considered. A general expression for the tunneling current is obtained with the Rashba and Dresselhaus effects and also elastic scattering of charge carriers on impurities taken into account. It is shown that the particular form of the tunneling conductance as a function of the voltage between layers is extremely sensitive to the relationship between the Rashba and Dresselhaus parameters. This makes it possible to determine the parameters of the spin-orbit interaction and the quantum scattering time directly from measurements of the tunneling conductance in the absence of magnetic field

  3. Topological honeycomb magnon Hall effect: A calculation of thermal Hall conductivity of magnetic spin excitations

    Owerre, S. A., E-mail: solomon@aims.ac.za [African Institute for Mathematical Sciences, 6 Melrose Road, Muizenberg, Cape Town 7945, South Africa and Perimeter Institute for Theoretical Physics, 31 Caroline St. N., Waterloo, Ontario N2L 2Y5 (Canada)

    2016-07-28

    Quite recently, the magnon Hall effect of spin excitations has been observed experimentally on the kagome and pyrochlore lattices. The thermal Hall conductivity κ{sup xy} changes sign as a function of magnetic field or temperature on the kagome lattice, and κ{sup xy} changes sign upon reversing the sign of the magnetic field on the pyrochlore lattice. Motivated by these recent exciting experimental observations, we theoretically propose a simple realization of the magnon Hall effect in a two-band model on the honeycomb lattice. The magnon Hall effect of spin excitations arises in the usual way via the breaking of inversion symmetry of the lattice, however, by a next-nearest-neighbour Dzyaloshinsky-Moriya interaction. We find that κ{sup xy} has a fixed sign for all parameter regimes considered. These results are in contrast to the Lieb, kagome, and pyrochlore lattices. We further show that the low-temperature dependence on the magnon Hall conductivity follows a T{sup 2} law, as opposed to the kagome and pyrochlore lattices. These results suggest an experimental procedure to measure thermal Hall conductivity within a class of 2D honeycomb quantum magnets and ultracold atoms trapped in a honeycomb optical lattice.

  4. DC conductivity and magnetic properties of piezoelectric–piezomagnetic composite system

    Hemeda, O.M.; Tawfik, A.; A-Al-Sharif; Amer, M.A.; Kamal, B.M.; El Refaay, D.E.; Bououdina, M.

    2012-01-01

    A series of composites (1−x) (Ni 0.8 Zn 0.2 Fe 2 O 4 )+x (BaTiO 3 ), where x=0%, 20%, 40%, 60%, 80% and 100% BT content, have been prepared by the standard ceramic technique, then sintered at 1200 °C for 8 h. X-ray diffraction analysis shows that the prepared composites consist of two phases, ferrimagnetic and ferroelectric. DC electrical resistivity, thermoelectric power, charge carriers concentration and charge carrier mobility have been studied at different temperatures. It was found that the DC electrical conductivity increases with increasing BT content. The values of the thermoelectric power were positive and negative for the composites indicating that there are two conduction mechanisms, hopping and band conduction, respectively. Using the values of DC electrical conductivity and thermoelectric power, the values of charge carrier mobility and the charge carrier concentration were calculated. Magnetic measurements (hysteresis loop and magnetic permeability) show that the magnetization decreases by increasing BT content. M–H loop of pure Ni 0.6 Zn 0.4 Fe 2 O 4 composite indicates that it is paramagnetic at room temperature and that the magnetization is diluted by increasing the BT content in the composite system. The value of magnetoelectric coefficient for the composites decreases by increasing BT content for all the compositions except for 40% BT content, which may be due to the low resistivity of magnetic phase compared with the BT phase that causes a leakage of induced charges on the piezoelectric phase. Since both ferroelectric and magnetic phases preserve their basic properties in the bulk composite, the present BT–NZF composite are potential candidates for applications as pollution sensors and electromagnetic waves. - Highlights: ► Studied composite has a high magnetoelectric coefficient compared with other composites. ► A p–n transition is observed for the composite with 80% BT and 100% BT content. ► Ni-ferrite can lead to a strong shift

  5. DC conductivity and magnetic properties of piezoelectric-piezomagnetic composite system

    Hemeda, O.M., E-mail: omhemeda@yahoo.co.uk [Tanta University, Faculty of Science, Physics Department (Egypt); Taif University, Faculty of Science, Physics Department (Saudi Arabia); Tawfik, A. [Taif University, Faculty of Science, Physics Department (Saudi Arabia); A-Al-Sharif [Moata University, Faculty of Science, Physics Department (Jordan); Amer, M.A. [Taif University, Faculty of Science, Physics Department (Saudi Arabia); Kamal, B.M.; El Refaay, D.E. [Suez Canal University, Faculty of Science, Physics Department (Egypt); Bououdina, M. [Nanotechnology Centre, College of Science, University of Bahrain, PO Box 32038 (Bahrain); Department of Physics, College of Science, University of Bahrain, PO Box 32038 (Bahrain)

    2012-11-15

    A series of composites (1-x) (Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4})+x (BaTiO{sub 3}), where x=0%, 20%, 40%, 60%, 80% and 100% BT content, have been prepared by the standard ceramic technique, then sintered at 1200 Degree-Sign C for 8 h. X-ray diffraction analysis shows that the prepared composites consist of two phases, ferrimagnetic and ferroelectric. DC electrical resistivity, thermoelectric power, charge carriers concentration and charge carrier mobility have been studied at different temperatures. It was found that the DC electrical conductivity increases with increasing BT content. The values of the thermoelectric power were positive and negative for the composites indicating that there are two conduction mechanisms, hopping and band conduction, respectively. Using the values of DC electrical conductivity and thermoelectric power, the values of charge carrier mobility and the charge carrier concentration were calculated. Magnetic measurements (hysteresis loop and magnetic permeability) show that the magnetization decreases by increasing BT content. M-H loop of pure Ni{sub 0.6} Zn{sub 0.4} Fe{sub 2}O{sub 4} composite indicates that it is paramagnetic at room temperature and that the magnetization is diluted by increasing the BT content in the composite system. The value of magnetoelectric coefficient for the composites decreases by increasing BT content for all the compositions except for 40% BT content, which may be due to the low resistivity of magnetic phase compared with the BT phase that causes a leakage of induced charges on the piezoelectric phase. Since both ferroelectric and magnetic phases preserve their basic properties in the bulk composite, the present BT-NZF composite are potential candidates for applications as pollution sensors and electromagnetic waves. - Highlights: Black-Right-Pointing-Pointer Studied composite has a high magnetoelectric coefficient compared with other composites. Black-Right-Pointing-Pointer A p-n transition is observed

  6. Hyper-resistivity and electron thermal conductivity due to destroyed magnetic surfaces in axisymmetric plasma equilibria

    Weening, R. H. [Department of Radiologic Sciences, Thomas Jefferson University, 901 Walnut Street, Philadelphia, Pennsylvania 19107-5233 (United States)

    2012-06-15

    In order to model the effects of small-scale current-driven magnetic fluctuations in a mean-field theoretical description of a large-scale plasma magnetic field B(x,t), a space and time dependent hyper-resistivity {Lambda}(x,t) can be incorporated into the Ohm's law for the parallel electric field E Dot-Operator B. Using Boozer coordinates, a theoretical method is presented that allows for a determination of the hyper-resistivity {Lambda}({psi}) functional dependence on the toroidal magnetic flux {psi} for arbitrary experimental steady-state Grad-Shafranov axisymmetric plasma equilibria, if values are given for the parallel plasma resistivity {eta}({psi}) and the local distribution of any auxiliary plasma current. Heat transport in regions of plasma magnetic surfaces destroyed by resistive tearing modes can then be modeled by an electron thermal conductivity k{sub e}({psi})=({epsilon}{sub 0}{sup 2}m{sub e}/e{sup 2}){Lambda}({psi}), where e and m{sub e} are the electron charge and mass, respectively, while {epsilon}{sub 0} is the permittivity of free space. An important result obtained for axisymmetric plasma equilibria is that the {psi}{psi}-component of the metric tensor of Boozer coordinates is given by the relation g{sup {psi}{psi}}({psi}){identical_to}{nabla}{psi} Dot-Operator {nabla}{psi}=[{mu}{sub 0}G({psi})][{mu}{sub 0}I({psi})]/{iota}({psi}), with {mu}{sub 0} the permeability of free space, G({psi}) the poloidal current outside a magnetic surface, I({psi}) the toroidal current inside a magnetic surface, and {iota}({psi}) the rotational transform.

  7. Low-Cost Timer to Measure the Terminal Velocity of a Magnet Falling through a Conducting Pipe

    Pathare, Shirish R.; Huli, Saurabhee; Lahane, Rohan; Sawant, Sumedh

    2014-01-01

    Dropping a magnet into a conductive pipe (made up of copper or brass or aluminum) is a very popular demonstration in many physics classrooms and laboratories. In this paper we present an inexpensive timer that can be used to measure the terminal velocity of the magnet falling through a conducting pipe. The timer assembly consists of Hall effect…

  8. The fluctuation Hall conductivity and the Hall angle in type-II superconductor under magnetic field

    Tinh, Bui Duc, E-mail: tinhbd@hnue.edu.vn [Institute of Research and Development, Duy Tan University, K7/25 Quang Trung, Danang (Viet Nam); Department of Physics, Hanoi National University of Education, 136 Xuan Thuy, Cau Giay, Hanoi (Viet Nam); Hoc, Nguyen Quang; Thu, Le Minh [Department of Physics, Hanoi National University of Education, 136 Xuan Thuy, Cau Giay, Hanoi (Viet Nam)

    2016-02-15

    Highlights: • The time-dependent Ginzburg–Landau was used to calculate fluctuation Hall conductivity and Hall angle in type-II superconductor in 2D and 3D. • We obtain analytical expressions for the fluctuation Hall conductivity and the Hall angle summing all Landau levels without need to cutoff higher Landau levels to treat arbitrary magnetic field. • The results were compared to the experimental data on YBCO. - Abstract: The fluctuation Hall conductivity and the Hall angle, describing the Hall effect, are calculated for arbitrary value of the imaginary part of the relaxation time in the frame of the time-dependent Ginzburg–Landau theory in type II-superconductor with thermal noise describing strong thermal fluctuations. The self-consistent Gaussian approximation is used to treat the nonlinear interaction term in dynamics. We obtain analytical expressions for the fluctuation Hall conductivity and the Hall angle summing all Landau levels without need to cutoff higher Landau levels to treat arbitrary magnetic field. The results are compared with experimental data on high-T{sub c} superconductor.

  9. Structure of slow shocks in a magnetized plasma with heat conduction

    Tsai, C.L.; Tsai, R.H.; Wu, B.H.; Lee, L.C.

    2002-01-01

    The structure of slow shocks in the presence of a heat conduction parallel to the local magnetic field is simulated from the set of magnetohydrodynamic equations. In this study, a pair of slow shocks is formed through the evolution of a current sheet initiated by the presence of a normal magnetic field. It is found that the slow shock consists of two parts: The isothermal main shock and foreshock. Significant jumps in plasma density, velocity and magnetic field occur across the main shock, but the temperature is found to be continuous across the main shock. The foreshock is featured by a smooth temperature variation and is formed due to the heat flow from downstream to upstream region. The plasma density downstream of the main shock decreases with time, while the downstream temperature increases with time, keeping the downstream pressure constant. It is shown that the jumps in plasma density, pressure, velocity, and magnetic field across the main shock are determined by the set of modified isothermal Rankine-Hugoniot conditions. It is also found that a jump in the temperature gradient is present across the main shock in order to satisfy the energy conservation. The present results can be applied to the heating in the solar corona and solar wind

  10. Probing beer aging chemistry by nuclear magnetic resonance and multivariate analysis

    Rodrigues, J.A.; Barros, A.S.; Carvalho, B.; Brandao, T.; Gil, Ana M.

    2011-01-01

    Graphical abstract: The use of nuclear magnetic resonance (NMR) metabonomics for monitoring the chemical changes occurring in beer exposed to forced aging (at 45 deg. C for up to 18 days) is described. Both principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) were applied to the NMR spectra of beer recorded as a function of aging and an aging trend was observed. Inspection of PLS-DA loadings and peak integration revealed the importance of well known markers (e.g. 5-HMF) as well as of other compounds: amino acids, higher alcohols, organic acids, dextrins and some still unassigned spin systems. 2D correlation analysis enabled relevant compound variations to be confirmed and inter-compound correlations to be assessed, thus offering improved insight into the chemical aspects of beer aging. Highlights: · Use of NMR metabonomics for monitoring the chemical changes occurring in beer exposed to forced aging. · Compositional variations evaluated by principal component analysis and partial least squares-discriminant analysis. · Results reveal importance of known markers and other compounds: amino and organic acids, higher alcohols, dextrins. · 2D correlation analysis reveals inter-compound relationships, offering insight into beer aging chemistry. - Abstract: This paper describes the use of nuclear magnetic resonance (NMR) spectroscopy, in tandem with multivariate analysis (MVA), for monitoring the chemical changes occurring in a lager beer exposed to forced aging (at 45 deg. C for up to 18 days). To evaluate the resulting compositional variations, both principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) were applied to the NMR spectra of beer recorded as a function of aging and a clear aging trend was observed. Inspection of PLS-DA loadings and peak integration enabled the changing compounds to be identified, revealing the importance of well known markers such as 5-hydroxymethylfurfural (5

  11. Probing beer aging chemistry by nuclear magnetic resonance and multivariate analysis

    Rodrigues, J.A. [CICECO-Department of Chemistry, University of Aveiro, Campus de Santiago, 3810-193 Aveiro (Portugal); Barros, A.S. [QOPNA-Department of Chemistry, University of Aveiro, Campus de Santiago, 3810-193 Aveiro (Portugal); Carvalho, B.; Brandao, T. [UNICER, Bebidas de Portugal, Leca do Balio, 4466-955, S. Mamede de Infesta (Portugal); Gil, Ana M., E-mail: agil@ua.pt [CICECO-Department of Chemistry, University of Aveiro, Campus de Santiago, 3810-193 Aveiro (Portugal)

    2011-09-30

    Graphical abstract: The use of nuclear magnetic resonance (NMR) metabonomics for monitoring the chemical changes occurring in beer exposed to forced aging (at 45 deg. C for up to 18 days) is described. Both principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) were applied to the NMR spectra of beer recorded as a function of aging and an aging trend was observed. Inspection of PLS-DA loadings and peak integration revealed the importance of well known markers (e.g. 5-HMF) as well as of other compounds: amino acids, higher alcohols, organic acids, dextrins and some still unassigned spin systems. 2D correlation analysis enabled relevant compound variations to be confirmed and inter-compound correlations to be assessed, thus offering improved insight into the chemical aspects of beer aging. Highlights: {center_dot} Use of NMR metabonomics for monitoring the chemical changes occurring in beer exposed to forced aging. {center_dot} Compositional variations evaluated by principal component analysis and partial least squares-discriminant analysis. {center_dot} Results reveal importance of known markers and other compounds: amino and organic acids, higher alcohols, dextrins. {center_dot} 2D correlation analysis reveals inter-compound relationships, offering insight into beer aging chemistry. - Abstract: This paper describes the use of nuclear magnetic resonance (NMR) spectroscopy, in tandem with multivariate analysis (MVA), for monitoring the chemical changes occurring in a lager beer exposed to forced aging (at 45 deg. C for up to 18 days). To evaluate the resulting compositional variations, both principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) were applied to the NMR spectra of beer recorded as a function of aging and a clear aging trend was observed. Inspection of PLS-DA loadings and peak integration enabled the changing compounds to be identified, revealing the importance of well known

  12. Surface charge conductivity of a topological insulator in a magnetic field: The effect of hexagonal warping

    Akzyanov, R. S.; Rakhmanov, A. L.

    2018-02-01

    We investigate the influence of hexagonal warping on the transport properties of topological insulators. We study the charge conductivity within Kubo formalism in the first Born approximation using low-energy expansion of the Hamiltonian near the Dirac point. The effects of disorder, magnetic field, and chemical-potential value are analyzed in detail. We find that the presence of hexagonal warping significantly affects the conductivity of the topological insulator. In particular, it gives rise to the growth of the longitudinal conductivity with the increase of the disorder and anisotropic anomalous in-plane magnetoresistance. Hexagonal warping also affects the quantum anomalous Hall effect and anomalous out-of-plane magnetoresistance. The obtained results are consistent with the experimental data.

  13. METHODOLOGICAL NOTES: Braking of a magnetic dipole moving with an arbitrary velocity through a conducting pipe

    Knyazev, B. A.; Kotel'nikov, Igor A.; Tyutin, A. A.; Cherkasskiĭ, Valerii S.

    2006-09-01

    Lectures introducing students to electromagnetic induction phenomena often feature the popular experiment in which a small magnet falling down a long conducting pipe is markedly decelerated by the retarding force due to Foucault eddy currents arising in the pipe. In this paper, a formula for the retarding force, valid both for low velocities (when the force is proportional to the velocity v of magnet motion) and high velocities (when it first decreases as v-1 and then as v-1/2), is derived. The last two regimes are analogous to the collisionless (and hence unbounded) acceleration of plasma electrons and have not been previously described in the literature. The calculation of the retarding force in the presence of a longitudinal cut in the pipe wall is carried out, and experiments to measure this force are discussed.

  14. Braking of a magnetic dipole moving with an arbitrary velocity through a conducting pipe

    Knyazev, B A; Kotel'nikov, Igor A; Tyutin, A A; Cherkasskii, Valerii S

    2006-01-01

    Lectures introducing students to electromagnetic induction phenomena often feature the popular experiment in which a small magnet falling down a long conducting pipe is markedly decelerated by the retarding force due to Foucault eddy currents arising in the pipe. In this paper, a formula for the retarding force, valid both for low velocities (when the force is proportional to the velocity v of magnet motion) and high velocities (when it first decreases as v -1 and then as v -1/2 ), is derived. The last two regimes are analogous to the collisionless (and hence unbounded) acceleration of plasma electrons and have not been previously described in the literature. The calculation of the retarding force in the presence of a longitudinal cut in the pipe wall is carried out, and experiments to measure this force are discussed. (methodological notes)

  15. Cellular target of weak magnetic fields: ionic conduction along actin filaments of microvilli.

    Gartzke, Joachim; Lange, Klaus

    2002-11-01

    The interaction of weak electromagnetic fields (EMF) with living cells is a most important but still unresolved biophysical problem. For this interaction, thermal and other types of noise appear to cause severe restrictions in the action of weak signals on relevant components of the cell. A recently presented general concept of regulation of ion and substrate pathways through microvilli provides a possible theoretical basis for the comprehension of physiological effects of even extremely low magnetic fields. The actin-based core of microfilaments in microvilli is proposed to represent a cellular interaction site for magnetic fields. Both the central role of F-actin in Ca2+ signaling and its polyelectrolyte nature eliciting specific ion conduction properties render the microvillar actin filament bundle an ideal interaction site for magnetic and electric fields. Ion channels at the tip of microvilli are connected with the cytoplasm by a bundle of microfilaments forming a diffusion barrier system. Because of its polyelectrolyte nature, the microfilament core of microvilli allows Ca2+ entry into the cytoplasm via nonlinear cable-like cation conduction through arrays of condensed ion clouds. The interaction of ion clouds with periodically applied EMFs and field-induced cation pumping through the cascade of potential barriers on the F-actin polyelectrolyte follows well-known physical principles of ion-magnetic field (MF) interaction and signal discrimination as described by the stochastic resonance and Brownian motor hypotheses. The proposed interaction mechanism is in accord with our present knowledge about Ca2+ signaling as the biological main target of MFs and the postulated extreme sensitivity for coherent excitation by very low field energies within specific amplitude and frequency windows. Microvillar F-actin bundles shielded by a lipid membrane appear to function like electronic integration devices for signal-to-noise enhancement; the influence of coherent signals

  16. Conducting water chemistry of the secondary coolant circuit of VVER-based nuclear power plant units constructed without using copper containing alloys

    Tyapkov, V. F.

    2014-07-01

    The secondary coolant circuit water chemistry with metering amines began to be put in use in Russia in 2005, and all nuclear power plant units equipped with VVER-1000 reactors have been shifted to operate with this water chemistry for the past seven years. Owing to the use of water chemistry with metering amines, the amount of products from corrosion of structural materials entering into the volume of steam generators has been reduced, and the flow-accelerated corrosion rate of pipelines and equipment has been slowed down. The article presents data on conducting water chemistry in nuclear power plant units with VVER-1000 reactors for the secondary coolant system equipment made without using copper-containing alloys. Statistical data are presented on conducting ammonia-morpholine and ammonia-ethanolamine water chemistries in new-generation operating power units with VVER-1000 reactors with an increased level of pH. The values of cooling water leaks in turbine condensers the tube system of which is made of stainless steel or titanium alloy are given.

  17. Magnetic resonance electrical impedance tomography for measuring electrical conductivity during electroporation

    Kranjc, M; Miklavčič, D; Bajd, F; Serša, I

    2014-01-01

    The electroporation effect on tissue can be assessed by measurement of electrical properties of the tissue undergoing electroporation. The most prominent techniques for measuring electrical properties of electroporated tissues have been voltage–current measurement of applied pulses and electrical impedance tomography (EIT). However, the electrical conductivity of tissue assessed by means of voltage–current measurement was lacking in information on tissue heterogeneity, while EIT requires numerous additional electrodes and produces results with low spatial resolution and high noise. Magnetic resonance EIT (MREIT) is similar to EIT, as it is also used for reconstruction of conductivity images, though voltage and current measurements are not limited to the boundaries in MREIT, hence it yields conductivity images with better spatial resolution. The aim of this study was to investigate and demonstrate the feasibility of the MREIT technique for assessment of conductivity images of tissues undergoing electroporation. Two objects were investigated: agar phantoms and ex vivo liver tissue. As expected, no significant change of electrical conductivity was detected in agar phantoms exposed to pulses of all used amplitudes, while a considerable increase of conductivity was measured in liver tissue exposed to pulses of different amplitudes. (paper)

  18. Synergistic effect of topography, surface chemistry and conductivity of the electrospun nanofibrous scaffold on cellular response of PC12 cells.

    Tian, Lingling; Prabhakaran, Molamma P; Hu, Jue; Chen, Menglin; Besenbacher, Flemming; Ramakrishna, Seeram

    2016-09-01

    Electrospun nanofibrous nerve implants is a promising therapy for peripheral nerve injury, and its performance can be tailored by chemical cues, topographical features as well as electrical properties. In this paper, a surface modified, electrically conductive, aligned nanofibrous scaffold composed of poly (lactic acid) (PLA) and polypyrrole (Ppy), referred to as o-PLAPpy_A, was fabricated for nerve regeneration. The morphology, surface chemistry and hydrophilicity of nanofibers were characterized by Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and water contact angle, respectively. The effects of these nanofibers on neuronal differentiation using PC12 cells were evaluated. A hydrophilic surface was created by Poly-ornithine coating, which was able to provide a better environment for cell attachment, and furthermore aligned fibers were proved to be able to guide PC12 cells grow along the fiber direction and be beneficial for neurite outgrowth. The cellular response of PC12 cells to pulsed electrical stimulation was evaluated by NF 200 and alpha tubulin expression, indicating that electrical stimulation with a voltage of 40mV could enhance the neurite outgrowth. The PC12 cells stimulated with electrical shock showed greater level of neurite outgrowth and smaller cell body size. Moreover, the PC12 cells under electrical stimulation showed better viability. In summary, the o-PLAPpy_A nanofibrous scaffold supported the attachment, proliferation and differentiation of PC12 cells in the absence of electrical stimulation, which could be potential candidate for nerve regeneration applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Quench in a conduction-cooled Nb3Sn SMES magnet

    Korpela, Aki; Lehtonen, Jorma; Mikkonen, Risto; Perälä, Raine

    2003-11-01

    Due to the rapid development of cryocoolers, conduction-cooled Nb3Sn devices are nowadays enabled. A 0.2 MJ conduction-cooled Nb3Sn SMES system has been designed and constructed. The nominal current of the coil was 275 A at 10 K. The quench tests have been performed and in this paper the experimental data are compared to the computational one. Due to a slow normal zone propagation, Nb3Sn magnets are not necessarily self-protective. In conduction-cooled coils, a thermal interface provides a protection method known as a quench back. The temperature rise in the coil during a quench was measured with a sensor located on the inner radius of the coil. The current decay was also monitored. The measured temperature increased for approximately 15 s after the current had already decayed. This temperature rise is due to the heat conduction from the hot spot. Thus, the measured temperature does not represent the hot-spot temperature. A computational quench model which takes into account quench back and heat conduction after the current decay was developed in order to understand the measured temperatures. According to the results, a quench back due to the eddy current induced heating of the thermal interface of an LTS coil was an adequate protection method.

  20. Flow of conductive fluid between parallel disks in an axial magnetic field, (2)

    Koike, Kazuo; Kamiyama, Shin-ichi

    1981-01-01

    The basic characteristics of the flow in a disc type non-equilibrium MHD power generator were studied. The flow of conductive fluid between parallel disks in an axial magnetic field was analyzed as the subsonic MHD turbulent approach flow of viscous compressible fluid, taking the electron temperature dependence of conductivity into account. The equations for the flow between disks are described by ordinary electromagnetic hydrodynamic approximation. Practical numerical calculation was performed for the non-equilibrium argon plasma seeded with potassium. The effects of the variation of characteristics of non-equilibrium plasma in main flow and boundary layer on the flow characteristics became clear. The qualitative tendency of the properties of MHD generators can be well explained. (Kato, T.)

  1. Basic setup for breast conductivity imaging using magnetic resonance electrical impedance tomography

    Lee, Byung Il; Oh, Suk Hoon; Kim, Tae-Seong; Woo, Eung Je; Lee, Soo Yeol; Kwon, Ohin; Seo, Jin Keun

    2006-01-01

    We present a new medical imaging technique for breast imaging, breast MREIT, in which magnetic resonance electrical impedance tomography (MREIT) is utilized to get high-resolution conductivity and current density images of the breast. In this work, we introduce the basic imaging setup of the breast MREIT technique with an investigation of four different imaging configurations of current-injection electrode positions and pathways through computer simulation studies. Utilizing the preliminary findings of a best breast MREIT configuration, additional numerical simulation studies have been carried out to validate breast MREIT at different levels of SNR. Finally, we have performed an experimental validation with a breast phantom on a 3.0 T MREIT system. The presented results strongly suggest that breast MREIT with careful imaging setups could be a potential imaging technique for human breast which may lead to early detection of breast cancer via improved differentiation of cancerous tissues in high-resolution conductivity images

  2. Simulation of a conductive shield plate for the focalization of transcranial magnetic stimulation in the rat.

    Gasca, Fernando; Richter, Lars; Schweikard, Achim

    2010-01-01

    Transcranial Magnetic Stimulation (TMS) in the rat is a powerful tool for investigating brain function. However, the state-of-the-art experiments are considerably limited because the stimulation usually affects undesired anatomical structures. A simulation of a conductive shield plate placed between the coil stimulator and the rat brain during TMS is presented. The Finite Element (FE) method is used to obtain the 3D electric field distribution on a four-layer rat head model. The simulations show that the shield plate with a circular window can improve the focalization of stimulation, as quantitatively seen by computing the three-dimensional half power region (HPR). Focalization with the shield plate showed a clear compromise with the attenuation of the induced field. The results suggest that the shield plate can work as a helpful tool for conducting TMS rat experiments on specific targets.

  3. Electrical conductivity of the Earth's mantle after one year of SWARM magnetic field measurements

    Civet, François; Thebault, Erwan; Verhoeven, Olivier; Langlais, Benoit; Saturnino, Diana

    2015-04-01

    We present a global EM induction study using L1b Swarm satellite magnetic field measurements data down to a depth of 2000 km. Starting from raw measurements, we first derive a model for the main magnetic field, correct the data for a lithospheric field model, and further select the data to reduce the contributions of the ionospheric field. These computations allowed us to keep a full control on the data processes. We correct residual field from outliers and estimate the spherical harmonic coefficients of the transient field for periods between 2 and 256 days. We used full latitude range and all local times to keep a maximum amount of data. We perform a Bayesian inversion and construct a Markov chain during which model parameters are randomly updated at each iteration. We first consider regular layers of equal thickness and extra layers are added where conductivity contrast between successive layers exceed a threshold value. The mean and maximum likelihood of the electrical conductivity profile is then estimated from the probability density function. The obtained profile particularly shows a conductivity jump in the 600-700 km depth range, consistent with the olivine phase transition at 660 km depth. Our study is the first one to show such a conductivity increase in this depth range without any a priori informations on the internal strucutres. Assuming a pyrolitic mantle composition, this profile is interpreted in terms of temperature variations in the depth range where the probability density function is the narrowest. We finally obtained a temperature gradient in the lower mantle close to adiabatic.

  4. Cytotoxicity of magnetic nanoparticles derived from green chemistry against human cells

    Hanumandla, Pranitha

    The core-shelled Fe3O4 magnetic nanoparticles (MNPs) have been extensively investigated by the researchers due to their diversified applications. Recently, the study on the toxicity of nanomaterials has been drawn increasing attention to reduce or mitigate the environmental hazards and health risk. The objectives of this thesis are three fold: 1) prepare series functionalized Fe3O4 MNPs and optimize the synthesis variables of; 2) characterize their nanostructures using the state-of-the-art instrumental techniques; and 3) evaluate their cytotoxicity by measurement of nitrogen monoxide (NO) release, reactive oxygen species (ROS) and single oxygen species (SOS) generation. In order to prepare the crystalline Fe3O4 MNPs, a cost-effective and user-friendly wet chemistry (Sol-Gel) method was used. Two Indian medicinal plants were extracted to derive the active chemicals, which were used to functionalize the Fe3O 4 MNPs. The results indicated that the Fe3O4 MNPs were well-indexed with the standard inverse spinel structure (PDF 65-3107, a=8.3905A, α = 90°). The particle's sizes varied from 6-10 nm with the Fe3O 4 MNPs acting as cores and medicinal extracts as shell. The active chemical components extracted from two Hygrophila auriculata/ Chlorophytum borivilianum are fatty acid, Saponins, sterols, carbohydrates and amino acids, which are in agreement with the reported data. Toxicological evaluations of MNPs indicated that the Fe3O4 MNPs functionalized with Hygrophila auriculata/ Chlorophytum borivilianum extract prepared at room temperature were toxic to the cells when compared to the control, and act in a mechanism similar to the actions of hydrogen peroxide (H2O2). These functionalized MNPs, which were prepared at 100 ° C, displayed similar mechanism of action to the anticancer drug (SN-38). It was also found that the MNPs prepared at lower temperatures are less toxic and showed similar mechanism of action as the sodium nitrite (NaNO 2).

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

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

    2016-04-01

    In most Latin American countries there are significant numbers of both missing people and forced disappearances, ∼71,000 Colombia alone. Successful detection of buried human remains by forensic search teams can be difficult in varying terrain and climates. Three clandestine burials were simulated at two different depths commonly encountered in Latin America. In order to gain critical knowledge of optimum geophysical detection techniques, burials were monitored using: ground penetrating radar, magnetic susceptibility, bulk ground conductivity and electrical resistivity up to twenty-two months post-burial. Radar survey results showed good detection of modern 1/2 clothed pig cadavers throughout the survey period on 2D profiles, with the 250MHz antennae judged optimal. Both skeletonised and decapitated and burnt human remains were poorly imaged on 2D profiles with loss in signal continuity observed throughout the survey period. Horizontal radar time slices showed good anomalies observed over targets, but these decreased in amplitude over the post-burial time. These were judged due to detecting disturbed grave soil rather than just the buried targets. Magnetic susceptibility and electrical resistivity were successful at target detection in contrast to bulk ground conductivity surveys which were unsuccessful. Deeper burials were all harder to image than shallower ones. Forensic geophysical surveys should be undertaken at suspected burial sites. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  6. Electromagnetic interaction between a rising spherical particle in a conducting liquid and a localized magnetic field

    Lyu, Z.; Tran, N.; Boeck, T.; Karcher, C.

    2017-07-01

    Lorentz force velocimetry (LFV) is a non-contact electromagnetic flow measurement technique for electrically conductive liquids. It is based on measuring the flow-induced force acting on an external permanent magnet. Motivated by extending LFV to liquid metal two-phase flow measurement, in a first test we consider the free rising of a non-conductive spherical particle in a thin tube of liquid metal (GaInSn) initially at rest. Here the measured force is due to the displacement flow induced by the rising particle. In this paper, numerical results are presented for three different analytical solutions of flows around a moving sphere under a localized magnetic field. This simplification is made since the hydrodynamic flow is difficult to measure or to compute. The Lorentz forces are compared to experiments. The aim of the present work is to check if our simple numerical model can provide Lorentz forces comparable to the experiments. The results show that the peak values of the Lorentz force from the analytical velocity fields provide us an upper limit to the measurement results. In the case of viscous flow around a moving sphere we recover the typical time-scale of Lorentz force signals.

  7. PIC Simulations of Velocity-space Instabilities in a Decreasing Magnetic Field: Viscosity and Thermal Conduction

    Riquelme, Mario; Quataert, Eliot; Verscharen, Daniel

    2018-02-01

    We use particle-in-cell (PIC) simulations of a collisionless, electron–ion plasma with a decreasing background magnetic field, {\\boldsymbol{B}}, to study the effect of velocity-space instabilities on the viscous heating and thermal conduction of the plasma. If | {\\boldsymbol{B}}| decreases, the adiabatic invariance of the magnetic moment gives rise to pressure anisotropies with {p}| | ,j> {p}\\perp ,j ({p}| | ,j and {p}\\perp ,j represent the pressure of species j (electron or ion) parallel and perpendicular to B ). Linear theory indicates that, for sufficiently large anisotropies, different velocity-space instabilities can be triggered. These instabilities in principle have the ability to pitch-angle scatter the particles, limiting the growth of the anisotropies. Our simulations focus on the nonlinear, saturated regime of the instabilities. This is done through the permanent decrease of | {\\boldsymbol{B}}| by an imposed plasma shear. We show that, in the regime 2≲ {β }j≲ 20 ({β }j\\equiv 8π {p}j/| {\\boldsymbol{B}}{| }2), the saturated ion and electron pressure anisotropies are controlled by the combined effect of the oblique ion firehose and the fast magnetosonic/whistler instabilities. These instabilities grow preferentially on the scale of the ion Larmor radius, and make {{Δ }}{p}e/{p}| | ,e≈ {{Δ }}{p}i/{p}| | ,i (where {{Δ }}{p}j={p}\\perp ,j-{p}| | ,j). We also quantify the thermal conduction of the plasma by directly calculating the mean free path of electrons, {λ }e, along the mean magnetic field, finding that {λ }e depends strongly on whether | {\\boldsymbol{B}}| decreases or increases. Our results can be applied in studies of low-collisionality plasmas such as the solar wind, the intracluster medium, and some accretion disks around black holes.

  8. Deformation of the free surface of a conducting fluid in the magnetic field of current-carrying linear conductors

    Zubarev, N.M.; Zubareva, O.V.

    2017-01-01

    The magnetic shaping problem is studied for the situation where a cylindrical column of a perfectly conducting fluid is deformed by the magnetic field of a system of linear current-carrying conductors. Equilibrium is achieved due to the balance of capillary and magnetic pressures. Two two-parametric families of exact solutions of the problem are obtained with the help of conformal mapping technique. In accordance with them, the column essentially deforms in the cross section up to its disintegration.

  9. Deformation of the free surface of a conducting fluid in the magnetic field of current-carrying linear conductors

    Zubarev, N. M.; Zubareva, O. V.

    2017-06-01

    The magnetic shaping problem is studied for the situation where a cylindrical column of a perfectly conducting fluid is deformed by the magnetic field of a system of linear current-carrying conductors. Equilibrium is achieved due to the balance of capillary and magnetic pressures. Two two-parametric families of exact solutions of the problem are obtained with the help of conformal mapping technique. In accordance with them, the column essentially deforms in the cross section up to its disintegration.

  10. Nuclear magnetic resonance and electrical conductivity measurements of diffusion and disorder in LiBr

    Hamann, H.; Reininghaus, J.; Richtering, H.

    1980-01-01

    Electrical conductivity and nuclear magnetic relaxation rates were measured with pure and doped LiBr between 400 K and the melting point (824 K). Prevalent intrinsic disorder was observed down to 470 K. The degree of thermal disorder is 5 X 10 -7 at 470 K and 5 X 10 -3 at the melting point. From the relaxation rates of 7 Li, which are caused by Li-diffusion and nuclear dipole interaction, mean jump frequencies of the cations are derived. Conductivities calculated from these frequencies for a jump process via neighbouring cation vacancies are in perfect agreement with directly measured conductivities. From relaxation rates of 81 Br with MgBr 2 -doped crystals jump frequencies of vacancies were obtained which are again in good agreement with those derived from the conductivity data. From motional narrowing of the 81 Br absorption line the jump frequency of the anions is obtained, which is much smaller than for the cations. Since this motional narrowing is not influenced by any doping, it is concluded that anion transport mainly occurs via pairs of cation and anion vacancies. (Auth.)

  11. Effect of Magnetic Mirror on the Asymmetry of the Radial Profile of Near-Wall Conductivity in Hall Thrusters

    Yu Daren; Liu Hui; Fu Haiyang

    2009-01-01

    Considering the actual magnetic field configuration in a Hall thruster, the effect of magnetic mirror on the radial profile of near-wall conductivity (NWC) is studied in this paper. The plasma electron dynamic process is described by the test particle method. The Monte Carlo scheme is used to solve this model. The radial profile of electron mobility is obtained and the role of magnetic mirror in NWC is analysed both theoretically and numerically. The numerical results show that the electron mobility peak due to NWC is inversely proportional to the magnetic mirror ratio and the asymmetry of electron mobility along the radial direction gets greater when the magnetic mirror is considered. This effect indicates that apart from the disparity in the magnetic field strength, the difference in the magnetic mirror ratio near the inner and outer walls would actually augment the asymmetry of the radial profile of NWC in Hall thrusters.

  12. Manipulating magnetism and conductance of an adatom-molecule junction on a metal surface: An ab initio study

    Tao, Kun; Stepanyuk, V.S.; Bruno, P.

    2008-01-01

    The state of the art ab initio calculations reveal the effect of a scanning tunneling microscopy tip on magnetic properties and conductance of a benzene-adatom sandwich on Cu(001). We concentrate on a benzene-Co system interacting with a Cr tip. Our studies give a clear evidence that magnetism...

  13. Conductive-cooled superconducting magnets and their applications; Chodendo wo mijikanishita reitoki chokurei hoshiki no chodendo jishaku

    Kuriyama, T.; Sasaki, T.; Urata, M. [Toshiba Corp., Tokyo (Japan)

    1998-01-01

    This paper describes an outline of conductive-cooled superconducting magnets, magnetic regenerator materials, and their applications. This magnet is composed of a 4K cryocooler, superconducting current lead, heat shield plate, support, and vacuum vessel. Cooling of the conductive coil is initiated by the operation of 4K cryocooler. It takes two days to one week for the cooling-down time from room temperature to the given temperature. During that time, users need to do nothing for the superconducting magnet. When the superconducting coil is cooled to the given temperature, current is applied to the coil for excitation. Thus, magnetic field is formed. Paying attention to the magnetic anomaly specific heat accompanied with magnetic phase transition of magnetic substance at the extremely low temperature, Toshiba has developed a 4K cryocooler using magnetic regenerator material by utilizing magnetic specific heat. Oxide superconductor is adopted for the current lead which is used at the temperature level below 80K. Inflow of the heat can be suppressed in one-tenth of the conventional current lead. As a result, a small size device having easy operability without using liquid helium has been developed. 6 refs., 4 figs.

  14. Structure of intermediate shocks and slow shocks in a magnetized plasma with heat conduction

    Tsai, C.L.; Wu, B.H.; Lee, L.C.

    2005-01-01

    The structure of slow shocks and intermediate shocks in the presence of a heat conduction parallel to the local magnetic field is simulated from the set of magnetohydrodynamic equations. This study is an extension of an earlier work [C. L. Tsai, R. H. Tsai, B. H. Wu, and L. C. Lee, Phys. Plasmas 9, 1185 (2002)], in which the effects of heat conduction are examined for the case that the tangential magnetic fields on the two side of initial current sheet are exactly antiparallel (B y =0). For the B y =0 case, a pair of slow shocks is formed as the result of evolution of the initial current sheet, and each slow shock consists of two parts: the isothermal main shock and the foreshock. In the present paper, cases with B y ≠0 are also considered, in which the evolution process leads to the presence of an additional pair of time-dependent intermediate shocks (TDISs). Across the main shock of the slow shock, jumps in plasma density, velocity, and magnetic field are significant, but the temperature is continuous. The plasma density downstream of the main shock decreases with time, while the downstream temperature increases with time, keeping the downstream pressure constant. The foreshock is featured by a smooth temperature variation and is formed due to the heat flow from downstream to upstream region. In contrast to the earlier study, the foreshock is found to reach a steady state with a constant width in the slow shock frame. In cases with B y ≠0, the plasma density and pressure increase and the magnetic field decreases across TDIS. The TDIS initially can be embedded in the slow shock's foreshock structure, and then moves out of the foreshock region. With an increasing B y , the propagation speed of foreshock leading edge tends to decrease and the foreshock reaches its steady state at an earlier time. Both the pressure and temperature downstreams of the main shock decrease with increasing B y . The results can be applied to the shock heating in the solar corona and

  15. The synergy of ultrasonic treatment and organic modifiers for tuning the surface chemistry and conductivity of multiwalled carbon nanotubes

    Omastová, M.; Mičušík, M.; Fedorko, P.; Pionteck, J.; Kovářová, Jana; Chehimi, M. M.

    2014-01-01

    Roč. 46, 10-11 (2014), s. 940-944 ISSN 0142-2421. [European Conference on Applications of Surface and Interface Analysis /15./ - ECASIA 2013. Cagliari, 13.10.2013-18.10.2013] Institutional support: RVO:61389013 Keywords : carbon nanotubes * surface modification * surfactant Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.245, year: 2014

  16. Influence of magnetic moment formation on the conductance of coupled quantum wires

    Puller, V I; Mourokh, L G; Bird, J P; Ochiai, Y

    2005-01-01

    In this paper, we develop a model for the resonant interaction between a pair of coupled quantum wires, under conditions where self-consistent effects lead to the formation of a local magnetic moment in one of the wires. Our analysis is motivated by the experimental results of Morimoto et al (2003 Appl. Phys. Lett. 82 3952), who showed that the conductance of one of the quantum wires exhibits a resonant peak at low temperatures, whenever the other wire is swept into the regime where local-moment formation is expected. In order to account for these observations, we develop a theoretical model for the inter-wire interaction that calculated the transmission properties of one (the fixed) wire when the device potential is modified by the presence of an extra scattering term, arising from the presence of the local moment in the swept wire. To determine the transmission coefficients in this system, we derive equations describing the dynamics of electrons in the swept and fixed wires of the coupled-wire geometry. Our analysis clearly shows that the observation of a resonant peak in the conductance of the fixed wire is correlated to the appearance of additional structure (near 0.75 x 2e 2 /h or 0.25 x 2e 2 /h) in the conductance of the swept wire, in agreement with the experimental results of Morimoto et al

  17. Synchronized conductivity modulation to realize broadband lossless magnetic-free non-reciprocity.

    Dinc, Tolga; Tymchenko, Mykhailo; Nagulu, Aravind; Sounas, Dimitrios; Alu, Andrea; Krishnaswamy, Harish

    2017-10-06

    Recent research has explored the spatiotemporal modulation of permittivity to break Lorentz reciprocity in a manner compatible with integrated-circuit fabrication. However, permittivity modulation is inherently weak and accompanied by loss due to carrier injection, particularly at higher frequencies, resulting in large insertion loss, size, and/or narrow operation bandwidths. Here, we show that the presence of absorption in an integrated electronic circuit may be counter-intuitively used to our advantage to realize a new generation of magnet-free non-reciprocal components. We exploit the fact that conductivity in semiconductors provides a modulation index several orders of magnitude larger than permittivity. While directly associated with loss in static systems, we show that properly synchronized conductivity modulation enables loss-free, compact and extremely broadband non-reciprocity. We apply these concepts to obtain a wide range of responses, from isolation to gyration and circulation, and verify our findings by realizing a millimeter-wave (25 GHz) circulator fully integrated in complementary metal-oxide-semiconductor technology.Optical non-reciprocity achieved through refractive index modulation can have its challenges and limitations. Here, Dinc et al. introduce the concept of non-reciprocity based on synchronized spatio-temporal modulation of conductivity to achieve different types of non-reciprocal functionality.

  18. Complex microwave conductivity of YBa2Cu3O7 in magnetic fields up to 500T

    Goettee, J.D.; Zerwekh, W.D.; Kudasov, Y.B.

    1994-01-01

    We have measured the complex conductivity of thin films of YBa 2 cu 3 O 7 (YBCO) superconductor down to temperatures of 4K and magnetic fields up to 500T. The highly oriented films were probed by 94 GHz radiation, with the external magnetic field applied perpendicular to the c-axis. These measurements allowed us to assign a value of 340 ± 40 for the upper critical field at T=O. The measurements were recently carried out at the pulsed field facility of the National High Magnetic Field Laboratory at Los Alamos using both Russian and American magnetic flux compression generators

  19. Effect of lanthanum substitution on dielectric relaxation, impedance response, conducting and magnetic properties of strontium hexaferrite

    Want, Basharat, E-mail: bawant@kashmiruniversity.ac.in; Bhat, Bilal Hamid; Ahmad, Bhat Zahoor

    2015-04-05

    Highlights: • The substitution of La affects the dielectric and magnetic properties of strontium hexaferrite. • The electric behaviour of the compound follows the Koop’s phenomenological theory. • The impedance study shows the role of grain boundaries to the electric properties of the compound. • The substitution of La to strontium hexaferrite reduces the resistive nature of grain boundaries. - Abstract: Lanthanum strontium hexaferrite Sr{sub 1−x}La{sub x}Fe{sub 12}O{sub 19} (x = 0, 0.08, 0.13 , 0.18) has been successfully synthesized by using citrate-precursor method and characterized by different techniques. The X-ray diffraction results revealed that the sample is crystalline in nature and is of single phase with the space group P63/mmc. The dielectric, conducting and impedance related studies have been carried out as a function of frequency and concentration of lanthanum in the frequency ranges of 20 Hz–3 MHz. Impedance studies were performed in the frequency domain to distinguish between bulk and grain boundary contributions of the material to the overall dielectric response. The electric response of the material was also modeled by an equivalent circuit and different circuit parameters were calculated. Magnetic characterization of the material was also performed and the effect of lanthanum concentration was studied. The hysteresis loop obtained from the magnetometer showed that with the increase of lanthanum concentration, the saturation magnetisation decreases while as coercivity increases.

  20. Losses Approximation for Soft Magnetic Composites Based on a Homogenized Equivalent Conductivity

    X. Ren

    2016-09-01

    Full Text Available Soft magnetic composites (SMC are a promising alternative to laminated steel in many Electrical Engineering applications. This is largely owing to their low level of eddy current losses. The electromagnetic behavior of SMC in electromagnetic devices cannot be easily predicted using standard numerical techniques such as the finite element method, mostly due to the computational cost required to model the material microstructure. Another difficulty lies in the high property contrast between the matrix and the inclusions. In this paper we propose a homogenization strategy to define the equivalent electromagnetic properties of SMC. For components made of SMC, the equivalent conductivity and permeability can be determined. These equivalent properties can be used to calculate eddy current losses or introduced into structural analysis tools to design electromagnetic devices.

  1. Hearing Benefit and Rated Satisfaction in Children with Unilateral Conductive Hearing Loss Using a Transcutaneous Magnetic-Coupled Bone-Conduction Hearing Aid.

    Polonenko, Melissa J; Carinci, Lora; Gordon, Karen A; Papsin, Blake C; Cushing, Sharon L

    Bilateral hearing is important for learning, development, and function in complex everyday environments. Children with conductive and mixed hearing loss (HL) have been treated for years with percutaneous coupling through an abutment, which achieves powerful output, but the implant site is susceptible to skin reactions and trauma. To overcome these complications, transcutaneous magnetic coupling systems were recently introduced. The purpose of the study was to evaluate whether the new transcutaneous magnetic coupling is an effective coupling paradigm for bone-conduction hearing aids (BCHAs). We hypothesized that magnetic coupling will (1) have limited adverse events, (2) provide adequate functional gain, (3) improve spatial hearing and aid listening in everyday situations, and (4) provide satisfactory outcomes to children and their families given one normal hearing ear. Retrospective analysis of audiological outcomes in a tertiary academic pediatric hospital. Nine children aged 5-17 yr with permanent unilateral conductive HL (UCHL) or mixed HL were implanted with a transcutaneous magnet-retained BCHA. Average hearing thresholds of the better and implanted ears were 12.3 ± 11.5 dB HL and 69.1 ± 11.6 dB HL, respectively, with a 59.4 ± 4.8 dB (mean ± standard deviation) conductive component. Data were extracted from audiology charts of the children with permanent UCHL or mixed HL who qualified for a surgically retained BCHA and agreed to the magnetic coupling. Outcomes were collected from the 3- to 9-mo follow-up appointments, and included surgical complications, aided audiometric thresholds with varying magnet strength, speech performance in quiet and noise, and patient-rated benefit and satisfaction using questionnaires. Repeated measures analysis of variance was used to analyze audiometric outcomes, and nonparametric tests were used to evaluate rated benefit and satisfaction. All nine children tolerated the device and only one child had discomfort at the wound

  2. Influence of frequency of the excitation magnetic field and material's electric conductivity on domain wall dynamics in ferromagnetic materials

    Chávez-González, A.F.; Pérez-Benítez, J.A.; Espina-Hernández, J.H.; Grössinger, R.; Hallen, J.M.

    2016-01-01

    The present work analyzes the influence of electric conductivity on the Magnetic Barkhausen Noise (MBN) signal using a microscopic model which includes the influence of eddy currents. This model is also implemented to explain the dependence of MBN on the frequency of the applied magnetic field. The results presented in this work allow analyzing the influence of eddy currents on MBN signals for different values of the material's electric conductivity and for different frequencies of applied magnetic field. Additionally, the outcomes of this research can be used as a reference to differentiate the influence of eddy currents from that of second phase particles in the MBN signal, which has been reported in previous works. - Highlights: • Electromagnetic simulation of MBN with eddy currents and micro-magnetism. • Influence of applied field frequency on MBN is explained. • Influence of electric conductivity on MBN is analyzed. • Hysteresis losses in ferromagnetic materials is analyzed using the model.

  3. The electrical conductivity of the Earth's upper mantle as estimated from satellite measured magnetic field variations. Ph.D. Thesis

    Didwall, E. M.

    1981-01-01

    Low latitude magnetic field variations (magnetic storms) caused by large fluctuations in the equatorial ring current were derived from magnetic field magnitude data obtained by OGO 2, 4, and 6 satellites over an almost 5 year period. Analysis procedures consisted of (1) separating the disturbance field into internal and external parts relative to the surface of the Earth; (2) estimating the response function which related to the internally generated magnetic field variations to the external variations due to the ring current; and (3) interpreting the estimated response function using theoretical response functions for known conductivity profiles. Special consideration is given to possible ocean effects. A temperature profile is proposed using conductivity temperature data for single crystal olivine. The resulting temperature profile is reasonable for depths below 150-200 km, but is too high for shallower depths. Apparently, conductivity is not controlled solely by olivine at shallow depths.

  4. Preparation, surface chemistry, and electrical conductivity of novel silicon carbide/polypyrrole composites containing an anionic surfactant

    Mičušík, M.; Omastová, M.; Boukerma, K.; Albouy, A.; Chehimi, M. M.; Trchová, Miroslava; Fedorko, P.

    2007-01-01

    Roč. 47, č. 8 (2007), s. 1198-1206 ISSN 0032-3888. [Bratislava International Conference on Macromolecules: Advanced Polymeric Materials /20./. Bratislava, 11.06.2006-15.06.2006] R&D Projects: GA AV ČR IAA400500504 Institutional research plan: CEZ:AV0Z40500505 Keywords : composites Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.272, year: 2007

  5. Synthesis, growth, and studies (crystal chemistry, magnetic chemistry) of actinide-based intermetallic compounds and alloys with a 1.1.1 stoichiometry

    Kergadallan, Yann

    1993-01-01

    The first part of this research thesis reports the study of the synthesis and reactivity of intermetallic compounds with a 1.1.1 stoichiometry. It presents the thermal properties of 1.1.1 compounds: general presentation of physical transitions, and of solid solutions and formation heat, application to actinides (reactivity analysis from phase diagrams, techniques of crystal synthesis and crystal growth. It describes experimental techniques: synthesis, determination of fusion temperature by dilatometry, methods used for crystal growth, characterisation techniques (metallography, X ray diffraction on powders, dilatometry). It discusses the obtained results in terms of characterisation of synthesised samples, of crystal growth, and of measurements of fusion temperature. The second part addresses crystal chemistry studies: structure of compounds with a 1.1.1 stoichiometry (Laves structures, Zr, Ti and Pu compounds), techniques of analysis by X-ray diffraction (on powders and on single crystals), result interpretation (UNiX compounds, AnTAl compounds with T being a metal from group VIII, AnTGa compounds, AnNiGe compounds, distance comparison, structure modifications under pressure). The third part concerns physical issues. The author addresses the following topics: physical properties of intermetallic 1.1.1 compounds (magnetism of yttrium phases, behaviour of uranium-based Laves phases, analysis of pseudo-binary diagrams, physical characteristics of uranium-based 1.1.1 compounds, predictions of physical measurements), analysis techniques (Moessbauer spectroscopy, SQUID for Superconducting Quantum Interference Device), and result interpretation

  6. Completeness relations for the electromagnetic modes of a cylindrical fibre with a radially dependent dielectric and magnetic permittivity and conductivity

    Hoenders, B.J.

    1986-01-01

    We consider an infinitely long conducting cylinder whose dielectric and magnetic permittivity and conductivity are functions of the distance from a point inside the cylinder to its axis. It is shown that the r-dependent part of the set of electromagnetic modes associated with such a cylinder is

  7. Transient Simulation of a Rotating Conducting Cylinder in a Transverse Magnetic Field

    2016-09-01

    the boundary conditions and magnetic field excitation. The balloon (no fringing at infinity ) boundary condition is used for the model. Two magnetic...cylinder to study the effects of the magnetic responses of the cylinder in the time history . Table 1 summarizes the electromagnetic properties of the...and phase shift angles of the magnetic flux density in the time history , at the center of the structural steel, aluminum, and copper cylinder

  8. Relativistic quantum Hall conductivity for 3D and 2D electron plasma in an external magnetic field

    Gonzalez Felipe, R.; Perez Martinez, A.; Perez-Rojas, H.

    1990-05-01

    The complete antisymmetric form of the conductivity tensor in the static limit, as well as the expression for the Hall conductivity, is obtained for the relativistic 3D and 2D electron gas in a magnetic field. The non-relativistic 2D limit is also discussed. The typical step form of the 2D Hall conductivity at zero temperature is obtained under the simple hypothesis of constancy of the chemical potential. (author). 6 refs, 1 fig

  9. Direct characterization of spin-transfer switching of nano-scale magnetic tunnel junctions using a conductive atomic force microscope

    Lee, Jia-Mou; Yang, Dong-Chin; Lee, Ching-Ming; Ye, Lin-Xiu; Chang, Yao-Jen; Wu, Te-ho; Lee, Yen-Chi; Wu, Jong-Ching

    2013-01-01

    We present an alternative method of spin-transfer-induced magnetization switching for magnetic tunnel junctions (MTJs) using a conductive atomic force microscope (CAFM) with pulsed current. The nominal MTJ cells' dimensions were 200 × 400 nm 2 . The AFM probes were coated with a Pt layer via sputtering to withstand up to several milliamperes. The pulsed current measurements, with pulse duration varying from 5 to 300 ms, revealed a magnetoresistance ratio of up to 120%, and an estimated intrinsic switching current density, based on the thermal activation model, of 3.94 MA cm −2 . This method demonstrates the potential skill to characterize nanometre-scale magnetic devices. (paper)

  10. Strain-dependent magnetism and electrical conductivity of La1-xSrxCoO3

    Zeneli, Orkidia

    2011-01-01

    In this work, the effects of epitaxial strain and film thickness on the lattice structure, microstructure, magnetization and electrical conduction of La 1-x Sr x CoO 3 (LSCO) (x=0.18 and 0.30) thin films have been studied using thickness-dependent film series on several types of single-crystalline substrates. Alternatively, the direct effect of strain has been probed using a piezoelectric substrate. La 0.7 Sr 0.3 CoO 3 is a ferromagnetic metal, whereas La 0.82 Sr 0.18 CoO 3 is at the phase boundary between the ferromagnetic metal and an insulating spin glass phase. Epitaxial biaxial strain in La 1-x Sr x CoO 3 (x=0.18-0.3) films is known to reduce the ferromagnetic double exchange interactions. It has further been suggested for the control of the crystal field splitting of the Co ions which may be utilized to manipulate the spin state. The LSCO (x = 0.18 and 0.30) films have been grown by pulsed laser deposition (PLD) on substrates of LaAlO 3 , SrTiO 3 , (PbMg 1/3 Nb 2/3 O 3 ) 0.72 (PbTiO 3 ) 0.28 (PMN-PT) and (LaAlO 3 ) 0.3 (Sr 2 TaAlO 6 ) 0.7 (LSAT), which provide different strain states and, in the case of PMN-PT, a reversibly controllable strain. Thickness-dependent series of La 0.82 Sr 0.18 CoO 3 on SrTiO 3 and LaAlO 3 as well as of La 0.7 Sr 0.3 CoO 3 on LSAT have been studied. The lattice parameters of the epitaxially grown films were determined from X-ray diffraction measurements (Bragg-Brentano method and reciprocal space mapping). Large tensile strains of 2% can be achieved in thicker films of up to 100 nm. On the other hand, the films under larger tensile strain have cracks and reveal ordered superstructures in HRTEM images which are tentatively attributed to ordered oxygen vacancies. The Curie temperature and the magnetic moment of the x=0.18 films increases towards larger film thickness in qualitative agreement with the joined effects of strain relaxation and finite thickness on magnetic ordering. In order to separate the direct strain effect from the

  11. Effect of elastic deformation and the magnetic field on the electrical conductivity of p-Si crystals

    Lys, R.; Pavlyk, B.; Didyk, R.; Shykorjak, J.; Karbovnyk, I.

    2018-03-01

    It is shown that at a deformation rate of 0.41 kg/min, the characteristic feature of the dependence of the surface resistance of the p-Si sample on the magnitude of its elastic deformation (R(σ)) is the reduction of the resistance during compression and unclamping. With the increase in the number of "compression-unclamping" cycles, the difference between the positions of the compression and unclamping curves decreases. The transformation of two types of magnetically sensitive defects occurs under the impact of a magnetic field on p-Si crystals. The defects are interrelated with two factors that cause the mutually opposite influence on the conductivity of the crystal. The first factor is that the action of the magnetic field decreases the activation energy of the dislocation holders, which leads to an increase in the electrical conductivity of the sample. The second factor is that due to the decay of molecules of oxygen-containing impurities in the magnetic field, the stable chemisorption bonds appear in the crystal that leads to a decrease in its conductivity. If the sample stays in the magnetic field for a long time, the one or the other mechanism predominates, causing a slow growth or decrease in resistance around a certain (averaged) value. Moreover, the frequency of such changes is greater in the deformed sample. The value of the surface resistance of p-Si samples does not change for a long time without the influence of the magnetic field.

  12. Experimental and numerical analysis for magnetically induced vibrations of conducting structure

    Nishio, Satoshi; Nakahira, Masataka; Miura, H.; Isono, A.

    1993-01-01

    The coupling effect between the electromagnetic field and mechanical response of a conducting structure is of importance in magnetic fusion devices as tokamak machine. The electromagnetically induced motion of the structure due to the Lorentz force induces additional eddy currents and further modifies the dynamic characteristics of the system. This paper is concerned with numerical modeling of the dynamic field-structure interaction and its verification by experimental tests. Here, a finite element numerical model for mechanical deformation and a wiregrid numerical model for eddy currents are employed for non-ferrous and elastic conductors. A computer code has been developed for 3-D thin shell structure. Experimental tests for the code verification were carried out by using a rectangular thin copper plate. Three kinds of the plate supporting systems, i.e., a cantilever system, a fixed both ends system and a simply supported ends system were investigated. A good agreement between the numerical and experimental results was obtained. Therefore, the computer code developed here is available for analyzing the electromagnetomechanical behavior of the plasma facing components of the tokamak device. (author)

  13. Magnetoacoustic Tomography with Magnetic Induction (MAT-MI) for Imaging Electrical Conductivity of Biological Tissue: A Tutorial Review

    Li, Xu; Yu, Kai; He, Bin

    2016-01-01

    Magnetoacoustic tomography with magnetic induction (MAT-MI) is a noninvasive imaging method developed to map electrical conductivity of biological tissue with millimeter level spatial resolution. In MAT-MI, a time-varying magnetic stimulation is applied to induce eddy current inside the conductive tissue sample. With the existence of a static magnetic field, the Lorentz force acting on the induced eddy current drives mechanical vibrations producing detectable ultrasound signals. These ultrasound signals can then be acquired to reconstruct a map related to the sample’s electrical conductivity contrast. This work reviews fundamental ideas of MAT-MI and major techniques developed in these years. First, the physical mechanisms underlying MAT-MI imaging are described including the magnetic induction and Lorentz force induced acoustic wave propagation. Second, experimental setups and various imaging strategies for MAT-MI are reviewed and compared together with the corresponding experimental results. In addition, as a recently developed reverse mode of MAT-MI, magneto-acousto-electrical tomography with magnetic induction (MAET-MI) is briefly reviewed in terms of its theory and experimental studies. Finally, we give our opinions on existing challenges and future directions for MAT-MI research. With all the reported and future technical advancement, MAT-MI has the potential to become an important noninvasive modality for electrical conductivity imaging of biological tissue. PMID:27542088

  14. New Concepts of Quality Assurance in Analytical Chemistry: Will They Influence the Way We Conduct Science in General?

    Andersen, Jens; Glasdam, Sidsel-Marie; Larsen, Daniel Bo

    2016-01-01

    , but in contemporary science two approaches to the implementation of statistics in decision making are used: 1. Short-term precision and 2. long-term precision. Both approaches are valid and both are described using the same methods of statistics. However, they lead to completely different conclusions and decisions....... Despite good intentions and new concepts, as well as practices and procedures for quality assurance, it is shown by these two examples that these efforts may be inadequate or mislead scientists into making major mistakes in the decision-making process. A set of equations is supplied, which are based......According to the guide Vocabulary in Metrology (VIM3) (JCGM, 2008), the definition of the concepts of trueness and accuracy has been revised, which has an important impact on analytical chemistry. Additionally, Eurachem/CITAC has published a new edition of the guide to Quantifying Uncertainty...

  15. Magnetic and conductivity study on Mn0.5Ru0.5Co2O4 spinel

    Bhowmik, R.N.; Ranganathan, R.

    2003-01-01

    The magnetic measurements suggest that Mn 0.5 Ru 0.5 Co 2 O 4 is a ferrimagnet with T c ≅ 140 K followed by irreversibility between zero field cooled and field cooled magnetization and peak in zero field cooled maximum at T m ≅ 100 K on decreasing the temperature. The scaling analysis of the conductivity (G) as a function of frequency (f) with functional form G p (f)/G o ∼ (f/f c ) n suggests two activated regimes at above and below of 210 K, respectively. The G o vs T shows semi-conducting behaviour of the sample. (author)

  16. Externally controlled local magnetic field in a conducting mesoscopic ring coupled to a quantum wire

    Maiti, Santanu K.

    2015-01-01

    In the present work, the possibility of regulating local magnetic field in a quantum ring is investigated theoretically. The ring is coupled to a quantum wire and subjected to an in-plane electric field. Under a finite bias voltage across the wire a net circulating current is established in the ring which produces a strong magnetic field at its centre. This magnetic field can be tuned externally in a wide range by regulating the in-plane electric field, and thus, our present system can be utilized to control magnetic field at a specific region. The feasibility of this quantum system in designing spin-based quantum devices is also analyzed

  17. FDTD analysis of 3-D conducting target coated by anisotropic magnetized plasma

    Xu Lijun; Liu Shaobin; Mo Jinjun; Yuan Naichang

    2006-01-01

    The JEC finite-difference time-domain (JEC-FDTD) method is extended to three dimensional anisotropic dispersive media- the magnetized plasma. The problem which incorporates both anisotropy and frequency dispersion at the same time is solved for the electromagnetic wave propagation. The three dimensional JEC-FDTD formulations for anisotropic magnetized plasma are derived. The method is applied to the electromagnetic scattering of dihedral corner reflector and sphere-cone coated with anisotropic magnetized plasma. By simulating the interaction of electromagnetic wave with magnetized plasma, some numerical results are obtained, which indicate that an appropriate plasma coating may efficiently reduce the RCS of a metallic target. (authors)

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

    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.

  19. Electric Conductivity of Hot and Dense Quark Matter in a Magnetic Field with Landau Level Resummation via Kinetic Equations

    Fukushima, Kenji; Hidaka, Yoshimasa

    2018-04-01

    We compute the electric conductivity of quark matter at finite temperature T and a quark chemical potential μ under a magnetic field B beyond the lowest Landau level approximation. The electric conductivity transverse to B is dominated by the Hall conductivity σH. For the longitudinal conductivity σ∥, we need to solve kinetic equations. Then, we numerically find that σ∥ has only a mild dependence on μ and the quark mass mq. Moreover, σ∥ first decreases and then linearly increases as a function of B , leading to an intermediate B region that looks consistent with the experimental signature for the chiral magnetic effect. We also point out that σ∥ at a nonzero B remains within the range of the lattice-QCD estimate at B =0 .

  20. Coordination-chemistry control of proton conductivity in the iconic metal-organic framework material HKUST-1.

    Jeong, Nak Cheon; Samanta, Bappaditya; Lee, Chang Yeon; Farha, Omar K; Hupp, Joseph T

    2012-01-11

    HKUST-1, a metal-organic framework (MOF) material containing Cu(II)-paddlewheel-type nodes and 1,3,5-benzenetricarboxylate struts, features accessible Cu(II) sites to which solvent or other desired molecules can be intentionally coordinated. As part of a broader investigation of ionic conductivity in MOFs, we unexpectedly observed substantial proton conductivity with the "as synthesized" version of this material following sorption of methanol. Although HKUST-1 is neutral, coordinated water molecules are rendered sufficiently acidic by Cu(II) to contribute protons to pore-filling methanol molecules and thereby enhance the alternating-current conductivity. At ambient temperature, the chemical identities of the node-coordinated and pore-filling molecules can be independently varied, thus enabling the proton conductivity to be reversibly modulated. The proton conductivity of HKUST-1 was observed to increase by ~75-fold, for example, when node-coordinated acetonitrile molecules were replaced by water molecules. In contrast, the conductivity became almost immeasurably small when methanol was replaced by hexane as the pore-filling solvent. © 2011 American Chemical Society

  1. To Solution of Classical Problem Pertaining to Magnetic Interference of Overhead Power Transmission Line on Extended Conducting Communications

    V. I. Glushko

    2013-01-01

    Full Text Available The paper considers a problem pertaining to magnetic interference of overhead power transmission lines and high-voltage bus bars of electrical installations on extended conducting communications and secondary circuits of relay protection and automation. A simplified task solution has been obtained on the basis of the Carson integral approximation.

  2. A new model of Earth's radial conductivity structure derived from over 10 yr of satellite and observatory magnetic data

    Püthe, Christoph; Kuvshinov, Alexey; Khan, Amir

    2015-01-01

    We present a newmodel of the radial (1-D) conductivity structure of Earth's mantle. This model is derived frommore than 10 yr of magnetic measurements from the satellites ørsted, CHAMP, SAC-C and the Swarm trio as well as the global network of geomagnetic observatories. After removal of core...

  3. Long-time tails of the heat-conductivity time correlation functions for a magnetized plasma - a kinetic theory approach

    Schoolderman, A.J.; Suttorp, L.G.

    1989-01-01

    The long-time behaviour of the longitudinal and the transverse heat conductivity time correlation functions for a magnetized one-component plasma is studied by means of kinetic theory. To that end these correlation functions, which are defined as the inverse Laplace transforms of the dynamic heat

  4. Impact of fluorine based reactive chemistry on structure and properties of high moment magnetic material

    Yang, Xiaoyu, E-mail: xiaoyu.yang@wdc.com; Chen, Lifan; Han, Hongmei; Fu, Lianfeng; Sun, Ming; Liu, Feng; Zhang, Jinqiu [Western Digital Corporation, 44100 Osgood Road, Fremont, California 94539 (United States)

    2014-05-07

    The impact of the fluorine-based reactive ion etch (RIE) process on the structural, electrical, and magnetic properties of NiFe and CoNiFe-plated materials was investigated. Several techniques, including X-ray fluorescence, 4-point-probe, BH looper, transmission electron microscopy (TEM), and electron energy loss spectroscopy (EELS), were utilized to characterize both bulk film properties such as thickness, average composition, Rs, ρ, Bs, Ms, and surface magnetic “dead” layers' properties such as thickness and element concentration. Experimental data showed that the majority of Rs and Bs changes of these bulk films were due to thickness reduction during exposure to the RIE process. ρ and Ms change after taking thickness reduction into account were negligible. The composition of the bulk films, which were not sensitive to surface magnetic dead layers with nano-meter scale, showed minimum change as well. It was found by TEM and EELS analysis that although both before and after RIE there were magnetic dead layers on the top surface of these materials, the thickness and element concentration of the layers were quite different. Prior to RIE, dead layer was actually native oxidation layers (about 2 nm thick), while after RIE dead layer consisted of two sub-layers that were about 6 nm thick in total. Sub-layer on the top was native oxidation layer, while the bottom layer was RIE “damaged” layer with very high fluorine concentration. Two in-situ RIE approaches were also proposed and tested to remove such damaged sub-layers.

  5. Numerical simulation of turbulent Taylor-Couette flow between conducting cylinders in an axial magnetic field at low magnetic Reynolds number

    Leng, Xueyuan; Kolesnikov, Yurii B.; Krasnov, Dmitry; Li, Benwen

    2018-01-01

    The effect of an axial homogeneous magnetic field on the turbulence in the Taylor-Couette flow confined between two infinitely long conducting cylinders is studied by the direct numerical simulation using a periodic boundary condition in the axial direction. The inner cylinder is rotating, and the outer one is fixed. We consider the case when the magnetic Reynolds number Rem ≪ 1, i.e., the influence of the induced magnetic field on the flow is negligible that is typical for industry and laboratory study of liquid metals. Relevance of the present study is based on the similarity of flow characteristics at moderate and high magnetic field for the cases with periodic and end-wall conditions at the large flow aspect ratio, as proven in the earlier studies. Two sets of Reynolds numbers 4000 and 8000 with several Hartmann numbers varying from 0 to 120 are employed. The results show that the mean radial induced electrical current, resulting from the interaction of axial magnetic field with the mean flow, leads to the transformation of the mean flow and the modification of the turbulent structure. The effect of turbulence suppression is dominating at a strong magnetic field, but before reaching the complete laminarization, we capture the appearance of the hairpin-like structures in the flow.

  6. Complex microwave conductivity of YBa2Cu3O7 in magnetic fields up to 500 T

    Bykov, A.I.; Dolotenko, M.I.; Fowler, C.M.; Freeman, B.L.; Goettee, J.D.; King, J.C.; Kolokolchikov, N.P.; Kudasov, Yu.B.; Lewis, W.; Marshall, B.R.; Papatheofanis, B.J.; Platonov, V.V.; Rodriguez, P.J.; Tatsenko, O.M.; Veeser, L.R.; Zerwekh, W.D.

    1995-01-01

    The complex microwave conductivity of thin, oriented YBa 2 Cu 3 O 7 films was measured at 94 GHz in pulsed, ultrahigh-magnetic fields up to 500 T. The c-axis of the film was perpendicular to the magnetic field. We estimate the upper critical field of the film at absolute zero as B c2 (0)=340±40 T. Dynamics of the transition into a normal state and connection with previous measurements of the reversibility line are discussed. (orig.)

  7. Spiral magnetic order, non-uniform states and electron correlations in the conducting transition metal systems

    Igoshev, P. A.; Timirgazin, M. A.; Arzhnikov, A. K.; Antipin, T. V.; Irkhin, V. Yu.

    2017-10-01

    The ground-state magnetic phase diagram is calculated within the Hubbard and s-d exchange (Kondo) models for square and simple cubic lattices vs. band filling and interaction parameter. The difference of the results owing to the presence of localized moments in the latter model is discussed. We employ a generalized Hartree-Fock approximation (HFA) to treat commensurate ferromagnetic (FM), antiferromagnetic (AFM), and incommensurate (spiral) magnetic phases. The electron correlations are taken into account within the Hubbard model by using the Kotliar-Ruckenstein slave boson approximation (SBA). The main advantage of this approach is a correct qualitative description of the paramagnetic phase: its energy becomes considerably lower as compared with HFA, and the gain in the energy of magnetic phases is substantially reduced.

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

    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)

  9. Feasibility study of parallel conduction cooling of NbTi magnet and sample probe in a cryogen-free magnet system

    Catarino, I.; Soni, V.; Barreto, J.; Martins, D.; Kar, S.

    2017-02-01

    The conduction cooling of both a 6 T superconducting magnet along with a sample probe in a parallel configuration is addressed in this work. A Gifford-McMahon (GM) cryocooler is directly cooling the NbTi magnet, which aims to be kept at 4 K, while a gas-gap heat switch (GGHS) manages the cooling power to be diverted to the sample probe, which may be swept from 4 K up to 300 K. A first prototype of a GGHS was customized and validated for this purpose. A sample probe assembly has been designed and assembled with the existing cryogen-free magnet system. The whole test setup and components are described and the preliminary experimental results on the integration are presented and discussed. The magnet was charged up to 3 T with a 4 K sample space and up to 1 T with a sweeping sample space temperature up to 300 K while acting on the GGHS. Despite some identified thermal insulation problems that occurred during this first test, the overall results demonstrated the feasibility of the cryogen-free parallel conduction cooling on study.

  10. Surface Chemistry of La0.99Sr0.01NbO4-d and Its Implication for Proton Conduction.

    Li, Cheng; Pramana, Stevin S; Ni, Na; Kilner, John; Skinner, Stephen J

    2017-09-06

    Acceptor-doped LaNbO 4 is a promising electrolyte material for proton-conducting fuel cell (PCFC) applications. As charge transfer processes govern device performance, the outermost surface of acceptor-doped LaNbO 4 will play an important role in determining the overall cell performance. However, the surface composition is poorly characterized, and the understanding of its impact on the proton exchange process is rudimentary. In this work, the surface chemistry of 1 atom % Sr-doped LaNbO 4 (La 0.99 Sr 0.01 NbO 4-d , denoted as LSNO) proton conductor is characterized using LEIS and SIMS. The implication of a surface layer on proton transport is studied using the isotopic exchange technique. It has shown that a Sr-enriched but La-deficient surface layer of about 6-7 nm thick forms after annealing the sample under static air at 1000 °C for 10 h. The onset of segregation is found to be between 600 and 800 °C, and an equilibrium surface layer forms after 10 h annealing. A phase separation mechanism, due to the low solubility of Sr in LaNbO 4 , has been proposed to explain the observed segregation behavior. The surface layer was concluded to impede the water incorporation process, leading to a reduced isotopic fraction after the D 2 16 O wet exchange process, highlighting the impact of surface chemistry on the proton exchange process.

  11. Correlation between conductivity and prognostic factors in invasive breast cancer using magnetic resonance electric properties tomography (MREPT)

    Kim, Soo-Yeon; Kim, Min Jung; Kim, Eun-Kyung; Moon, Hee Jung; Yoon, Jung Hyun; Shin, Jaewook; Kim, Dong-Hyun

    2016-01-01

    To investigate the correlation between conductivity and prognostic factors of invasive breast cancer using magnetic resonance electric properties tomography (MREPT). This retrospective study was approved by the Institutional Review Board, and verbal informed consent was obtained prior to breast MRI. This study included 65 women with surgically confirmed invasive breast cancers measuring 1 cm or larger on T2-weighted fast spin echo (FSE). Phase-based MREPT and the coil combination technique were used to reconstruct conductivity. Simple and multiple linear regression analysis were used to find an independent factor associated with conductivity. In total tumours, tumours with HER-2 overexpression showed lower conductivity than those without, and HER-2 overexpression was independently associated with conductivity. In 37 tumours 2 cm or larger, tumours with high mitosis or PR positivity showed higher conductivity than those without, and high mitosis and PR positivity were independently associated with conductivity. In 28 tumours 1-2 cm in size, there were no differences in conductivity according to the prognostic factors. Conductivity values measured using MREPT are associated with the HER-2 overexpression status, and may provide information about mitosis and the PR status of invasive breast cancers 2 cm or larger. (orig.)

  12. Clay/Polyaniline Hybrid through Diazonium Chemistry: Conductive Nanofiller with Unusual Effects on Interfacial Properties of Epoxy Nanocomposites.

    Jlassi, Khouloud; Chandran, Sarath; Poothanari, Mohammed A; Benna-Zayani, Mémia; Thomas, Sabu; Chehimi, Mohamed M

    2016-04-12

    The concept of conductive network structure in thermoset matrix without sacrificing the inherent mechanical properties of thermoset polymer (e.g., epoxy) is investigated here using "hairy" bentonite fillers. The latter were prepared through the in situ polymerization of aniline in the presence of 4-diphenylamine diazonium (DPA)-modified bentonite (B-DPA) resulting in a highly exfoliated bentonite-DPA/polyaniline (B-DPA/PANI). The nanocomposite filler was mixed with diglycidyl ether of bisphenol A (DGEBA), and the curing agent (4,4'-diaminodiphenylsulfone) (DDS) at high temperature in order to obtain nanocomposites through the conventional melt mixing technique. The role of B-DPA in the modification of the interface between epoxy and B-DPA/polyaniline (B-DPA/PANI) is investigated and compared with the filler B/PANI prepared without any diazonium modification of the bentonite. Synergistic improvement in dielectric properties and mechanical properties points to the fact that the DPA aryl groups from the diazonium precursor significantly modify the interface by acting as an efficient stress transfer medium. In DPA-containing nanocomposites, unique fibril formation was observed on the fracture surface. Moreover, dramatic improvement (210-220%) in fracture toughness of epoxy composite was obtained with B-DPA/PANI filler as compared to the weak improvement of 20-30% noted in the case of the B/PANI filler. This work shows that the DPA diazonium salt has an important effect on the improvement of the interfacial properties and adhesion of DGEBA and clay/PANI nanofillers.

  13. A simple solution for reducing artefacts due to conductive and dielectric effects in clinical magnetic resonance imaging at 3 T

    Sreenivas, M.; Lowry, M.; Gibbs, P.; Pickles, M.; Turnbull, L.W.

    2007-01-01

    The quality of imaging obtained at high magnetic field strengths can be degraded by various artefacts due to conductive and dielectric effects, which leads to loss of signal. Various methods have been described and used to improve the quality of the image affected by such artefacts. In this article, we describe the construction and use of a simple solution that can be used to diminish artefacts due to conductive and dielectric effects in clinical imaging at 3 T field strength and thereby improve the diagnostic quality of the images obtained

  14. Differential conductance measurements of low-resistance CoFeB/MgO/CoFeB magnetic tunnel junctions

    Nishioka, S.; Hamada, Y.V.; Matsumoto, R.; Mizuguchi, M.; Shiraishi, M.; Fukushima, A.; Kubota, H.; Nagahama, T.; Yuasa, S.; Maehara, H.; Nagamine, Y.; Tsunekawa, K.; Djayaprawira, D.D.; Watanabe, N.; Suzuki, Y.

    2007-01-01

    We measured differential conductance spectra of magnetic tunnel junctions (MTJs) with thin MgO barrier and low-resistance area product. The spectra of MTJs with MgO barrier thicker than 1.05 nm were essentially the same except for slight decrease of contributions from low-energy excitations, such as magnons. The spectra of MTJ with 1.01 nm MgO barrier were thoroughly different from the MTJs with thicker barrier. The result reveals that an MTJ with very thin MgO barrier thickness has different conduction characteristics from those with thicker MgO barriers

  15. A simple solution for reducing artefacts due to conductive and dielectric effects in clinical magnetic resonance imaging at 3 T

    Sreenivas, M. [Department of Radiology (Yorkshire Deanery-East), Hull Royal Infirmary, Anlaby Road, Hull HU3 2JZ (United Kingdom)]. E-mail: aprilsreenivas@hotmail.com; Lowry, M. [Centre for Magnetic Resonance Investigations, University of Hull, Hull Royal Infirmary, Anlaby Road, 1PR, Hull HU3 2JZ (United Kingdom); Gibbs, P. [Centre for Magnetic Resonance Investigations, University of Hull, Hull Royal Infirmary, Anlaby Road, 1PR, Hull HU3 2JZ (United Kingdom); Pickles, M. [Centre for Magnetic Resonance Investigations, University of Hull, Hull Royal Infirmary, Anlaby Road, 1PR, Hull HU3 2JZ (United Kingdom); Turnbull, L.W. [Centre for Magnetic Resonance Investigations, University of Hull, Hull Royal Infirmary, Anlaby Road, 1PR, Hull HU3 2JZ (United Kingdom)

    2007-04-15

    The quality of imaging obtained at high magnetic field strengths can be degraded by various artefacts due to conductive and dielectric effects, which leads to loss of signal. Various methods have been described and used to improve the quality of the image affected by such artefacts. In this article, we describe the construction and use of a simple solution that can be used to diminish artefacts due to conductive and dielectric effects in clinical imaging at 3 T field strength and thereby improve the diagnostic quality of the images obtained.

  16. Dynamo generation of a magnetic field by decaying Lehnert waves in a highly conducting plasma

    Mizerski, Krzysztof A.; Moffatt, H. K.

    2018-03-01

    Random waves in a uniformly rotating plasma in the presence of a locally uniform seed magnetic field and subject to weak kinematic viscosity ? and resistivity ? are considered. These "Lehnert" waves may have either positive or negative helicity, and it is supposed that waves of a single sign of helicity are preferentially excited by a symmetry-breaking mechanism. A mean electromotive force proportional to ? is derived, demonstrating the conflicting effects of the two diffusive processes. Attention is then focussed on the situation ?, relevant to conditions in the universe before and during galaxy formation. An ?-effect, axisymmetric about the rotation vector, is derived, decaying on a time-scale proportional to ?; this amplifies a large-scale seed magnetic field to a level independent of ?, this field being subsequently steady and having the character of a "fossil field". Subsequent evolution of this fossil field is briefly discussed.

  17. Point explosion in a medium with magnetic field and finite conductivity effects in the magnetohydrodynamic model

    Bergel'son, A.M.; Rajzer, Yu.P.; Surzhikov, S.T.

    1991-01-01

    Explosion in vacuum or in rarefied gas in the presence of magnetic field is a prototype of a series of natural cosmic and laboratory processes 'spherical' explosion is considered in MHD approximation. The problem, really two-dimensional in the case of uniform medium, is transformed to unidimensional one in result of corresponding angle averaging. These problems are solved with the use of the scheme of the second order accuracy of large particle method with introduction of artificial viscosity

  18. Valence, magnetism and conduction in the intermediate valence compounds: the case SmB6

    Derr, J.

    2006-09-01

    In some rare earth based compounds, the 4f level is situated so close to the Fermi level that the valence of the compound can become intermediate between two integer values. The so called 'intermediate valence' compound of Samarium hexaboride (SmB 6 ) is one typical example of the exciting physics which can result from this quantum equilibrium between two valence configurations. The first configuration (Sm 2+ ) corresponds to an insulating and non magnetic state whereas the second one (Sm 3+ ) would theoretically give a magnetic and metallic ground state. This dissertation deals with the influence of pressure on this equilibrium. Specific heat measurements under pressure evidenced a new long range magnetic ordering for pressures higher than p c ∼ 10 GPa. On another hand, transport measurements measured for the first time in good conditions of hydrostatics found a reliable and reproducible critical pressure for the insulator to metal transition equal to p c . The phase diagram of SmB 6 is now well known and the observation for the first time of a magnetic anomaly in the high pressure resistivity curves certifies that the onset of the magnetic phase really coincide with the closure of the gap. This change at the critical pressure p c is discussed in a general frame taking into account the Kondo lattice temperature as a key parameter for the renormalization of the wavefunction from one integer configuration to the other whereas the valence itself is still intermediate. This general idea seems to be valid also for other systems studied in this dissertation like SmS or TmSe and could even be valid for more general cases (Ytterbium, Cerium). In the same time, resistivity measurements under uniaxial stress were undertaken. The result is a strong anisotropy effect observed on the pressure dependence of the residual resistivity in the compound SmB 6 . The comparison with the transport under hydrostatic conditions enables us to consider a new idea for the nature of the gap

  19. Mantle conductivity obtained by 3-D inversion of magnetic satellite data

    Kuvshinov, A.; Olsen, Nils

    distributed geomagnetic observatories. Due to the high computational load of a 3-D inversion (requiring thousands of forward calculations), a comprehensive numerical framework is developed to increase the efficiency of the inversion.In particular, we take an advantage of specific features of the IE approach...... and perform the most consuming-time part of the IE forward simulations (the calculation of electric and magnetic tensor Green’s functions) only once. Approximate calculation of the data sensitivities also gives essential speed up of the inversion. We validate our inversion scheme using synthetic induction...

  20. Vertical variation in groundwater chemistry inferred from fluid specific-conductance well logging of the Snake River Plain Basalt aquifer, Idaho National Engineering Laboratory, southeastern Idaho

    Wood, S.H.; Bennecke, W.

    1994-01-01

    Well logging of electrical fluid specific conductance (C s ) shows that permeable zones yielding ground water to intrawell flows and the water columns in some wells at INEL have highly different chemistry, with as much as a two-fold variation in C s . This suggests that dedicated-pump sampling of ground water in the aquifer may not be representative of the chemistry of the waste plumes migrating southwest of the nuclear facilities. Natural background C s in basalt-aquifer ground water of this part of the Snake River Plain aquifer is less than 325μS/cm (microSiemans/cm), and total dissolved solids in mg/L units, (TDS) ∼ 0.6C s . This relationship underestimates TDS for waters with chemical waste, when C s is above 800 μS/cm. At well 59 near the ICPP water of 1115 μS/cm (∼6570+ mg/L TDS) enters the well from a permeable zone between 521 and 537 ft depth; the zone being 60 ft below the water level and water of 550 μS/cm. At the time of logging (9/14/93) the 1115/μS/cm water was flowing down the well, mixing with less concentrated waters and exciting at 600 or 624-ft depth. Waste water disposed of down the injection well at ICPP until 1984 was estimated to have a C 5 of 1140 μS/cm, identical to the water detected in logging. 29 refs., 8 figs., 1 tab

  1. The electrical conductivity of the upper mantle and lithosphere from satellite magnetic signal due to ocean tidal flow

    Schnepf, N. R.; Kuvshinov, A. V.; Grayver, A.; Sabaka, T. J.; Olsen, N.

    2015-12-01

    Global electromagnetic (EM) studies provide information on mantle electrical conductivity with the ultimate aim of understanding the composition, structure, and dynamics of Earth's interior. There is great much interest in mapping the global conductivity of the lithosphere and upper mantle (i.e., depths of 10-400 km) because recent laboratory experiments demonstrate that the electrical conductivity of minerals in these regions are greatly affected by small amounts of water or by partial melt. For decades, studies of lithospheric/mantle conductivity were based on interpretation of magnetic data from a global network of observatories. The recent expansion in magnetic data from low-Earth orbiting satellite missions (Ørsted, CHAMP, SAC-C, and Swarm) has led to a rising interest in probing Earth from space. The largest benefit of using satellite data is much improved spatial coverage. Additionally, and in contrast to ground-based data, satellite data are overall uniform and very high quality. Probing the conductivity of the lithosphere and upper mantle requires EM variations with periods of a few hours. This is a challenging period range for global EM studies since the ionospheric (Sq) source dominates these periods and has a much more complex spatial structure compared to the magnetospheric ring current. Moreover, satellite-based EM induction studies in principle cannot use Sq data since the satellites fly above the Sq source causing the signals to be seen by the satellite as a purely internal source, thus precluding the separation of satellite Sq signals into internal and external parts. Lastly, magnetospheric and ionospheric sources interact inductively with Earth's conducting interior. Fortunately, there exists an alternative EM source in the Sq period range: electric currents generated by oceanic tides. Tides instead interact galvanically with the lithosphere (i.e. by direct coupling of the source currents in the ocean with the underlying substrate), enabling

  2. Effect of variable viscosity on laminar convection flow of an electrically conducting fluid in uniform magnetic field

    Chakraborty S.

    2002-01-01

    Full Text Available The flow of a viscous incompressible electrically conducting fluid on a continuous moving flat plate in presence of uniform transverse magnetic field, is studied. The flat plate which is continuously moving in its own plane with a constant speed is considered to be isothermally heated. Assuming the fluid viscosity as an inverse linear function of temperature, the nature of fluid velocity and temperature in presence of uniform magnetic field are shown for changing viscosity parameter at different layers of the medium. Numerical solutions are obtained by using Runge-Kutta and Shooting method. The coefficient of skin friction and the rate of heat transfer are calculated at different viscosity parameter and Prandt l number. .

  3. Magnetization and spin-polarized conductance of asymmetrically hydrogenated graphene nanoribbons: significance of sigma bands

    Honda, Syuta; Inuzuka, Kouhei; Inoshita, Takeshi; Ota, Norio; Sano, Nobuyuki

    2014-01-01

    The magnetization and spin transport of asymmetric zigzag-edge graphene nanoribbons, terminated by hydrogen on one edge while unterminated on the other edge, were investigated by a combination of first-principles calculations and a tight-binding approach. At the unterminated edge, a spin-polarized σ edge state of minority spin appears near the Fermi level and contributes to spin transport. This state enters the band gap for ribbon widths of less than 15 chains, dominating the spin-polarized current. This indicates the importance of the σ edge states in the design of spintronic devices using graphene nanoribbons. We also examined the case where the ‘unterminated’ edge is partially terminated by hydrogen. (paper)

  4. Nonintegrability of an extensible conducting rod in a uniform magnetic field

    Van der Heijden, G H M [Centre for Nonlinear Dynamics and its Applications, Department of Civil, Environmental and Geomatic Engineering, University College London, Gower Street, London WC1E 6BT (United Kingdom); Yagasaki, K, E-mail: g.heijden@ucl.ac.uk, E-mail: yagasaki@ie.niigata-u.ac.jp [Mathematics Division, Department of Information Engineering, Niigata University, Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181 (Japan)

    2011-12-09

    The equilibrium equations for an isotropic Kirchhoff rod are known to be completely integrable. It is also known that neither the effects of extensibility and shearability, nor the effects of a uniform magnetic field, individually break integrability. Here, we show, by means of a Melnikov-type analysis, that, when combined, these effects do break integrability giving rise to spatially chaotic configurations of the rod. A previous analysis of the problem suffered from the presence of an Euler-angle singularity. Our analysis provides an example of how in a system with such a singularity a Melnikov-type technique can be applied by introducing an artificial unfolding parameter. This technique is applicable to more general problems. (paper)

  5. [Evaluation of hazards caused by magnetic field emitted from magnetotherapy applicator to the users of bone conduction hearing prostheses].

    Zradziński, Patryk; Karpowicz, Jolanta; Gryz, Krzysztof; Leszko, Wiesław

    2017-06-27

    Low frequency magnetic field, inducing electrical field (Ein) inside conductive structures may directly affect the human body, e.g., by electrostimulation in the nervous system. In addition, the spatial distribution and level of Ein are disturbed in tissues neighbouring the medical implant. Numerical models of magneto-therapeutic applicator (emitting sinusoidal magnetic field of frequency 100 Hz) and the user of hearing implant (based on bone conduction: Bonebridge type - IS-BB or BAHA (bone anchorde hearing aid) type - IS-BAHA) were worked out. Values of Ein were analyzed in the model of the implant user's head, e.g., physiotherapist, placed next to the applicator. It was demonstrated that the use of IS-BB or IS-BAHA makes electromagnetic hazards significantly higher (up to 4-fold) compared to the person without implant exposed to magnetic field heterogeneous in space. Hazards for IS-BAHA users are higher than those for IS-BB users. It was found that applying the principles of directive 2013/35/EU, at exposure to magnetic field below exposure limits the direct biophysical effects of exposure in hearing prosthesis users may exceed relevant limits. Whereas applying principles and limits set up by Polish labor law or the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines, the compliance with the exposure limits also ensures the compliance with relevant limits of electric field induced in the body of hearing implant user. It is necessary to assess individually electromagnetic hazard concerning hearing implant users bearing in mind significantly higher hazards to them compared to person without implant or differences between levels of hazards faced by users of implants of various structural or technological solutions. Med Pr 2017;68(4):469-477. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  6. Evaluation of hazards caused by magnetic field emitted from magnetotherapy applicator to the users of bone conduction hearing prostheses

    Patryk Zradziński

    2017-08-01

    Full Text Available Background: Low frequency magnetic field, inducing electrical field (Ein inside conductive structures may directly affect the human body, e.g., by electrostimulation in the nervous system. In addition, the spatial distribution and level of Ein are disturbed in tissues neighbouring the medical implant. Material and Methods: Numerical models of magneto-therapeutic applicator (emitting sinusoidal magnetic field of frequency 100 Hz and the user of hearing implant (based on bone conduction: Bonebridge type – IS-BB or BAHA (bone anchorde hearing aid type – IS-BAHA were worked out. Values of Ein were analyzed in the model of the implant user’s head, e.g., physiotherapist, placed next to the applicator. Results: It was demonstrated that the use of IS-BB or IS-BAHA makes electromagnetic hazards significantly higher (up to 4-fold compared to the person without implant exposed to magnetic field heterogeneous in space. Hazards for IS-BAHA users are higher than those for IS-BB users. It was found that applying the principles of directive 2013/35/EU, at exposure to magnetic field below exposure limits the direct biophysical effects of exposure in hearing prosthesis users may exceed relevant limits. Whereas applying principles and limits set up by Polish labor law or the International Commission on Non-Ionizing Radiation Protection (ICNIRP guidelines, the compliance with the exposure limits also ensures the compliance with relevant limits of electric field induced in the body of hearing implant user. Conclusions: It is necessary to assess individually electromagnetic hazard concerning hearing implant users bearing in mind significantly higher hazards to them compared to person without implant or differences between levels of hazards faced by users of implants of various structural or technological solutions. Med Pr 2017;68(4:469–477

  7. Couette flow of a hydro-magnetic electrically conducting fluid with ...

    Numerical solution of the problem of Couette flow of a hydromagnetic electrically conducting fluid has been obtained where the temperature of the fluid is assumed to vary exponentially. Results obtained for the flow velocity, temperature, skin friction and rate of heat transfer indicate that the temperature is higher when the ...

  8. Magnetic moment, vorticity-spin coupling and parity-odd conductivity of chiral fermions in 4-dimensional Wigner functions

    Gao, Jian-hua [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, Shandong 264209 (China); Wang, Qun, E-mail: qunwang@ustc.edu.cn [Interdisciplinary Center for Theoretical Study and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States)

    2015-10-07

    We demonstrate the emergence of the magnetic moment and spin-vorticity coupling of chiral fermions in 4-dimensional Wigner functions. In linear response theory with space–time varying electromagnetic fields, the parity-odd part of the electric conductivity can also be derived which reproduces results of the one-loop and the hard-thermal or hard-dense loop. All these properties show that the 4-dimensional Wigner functions capture comprehensive aspects of physics for chiral fermions in electromagnetic fields.

  9. Magnetic moment, vorticity-spin coupling and parity-odd conductivity of chiral fermions in 4-dimensional Wigner functions

    Jian-hua Gao

    2015-10-01

    Full Text Available We demonstrate the emergence of the magnetic moment and spin-vorticity coupling of chiral fermions in 4-dimensional Wigner functions. In linear response theory with space–time varying electromagnetic fields, the parity-odd part of the electric conductivity can also be derived which reproduces results of the one-loop and the hard-thermal or hard-dense loop. All these properties show that the 4-dimensional Wigner functions capture comprehensive aspects of physics for chiral fermions in electromagnetic fields.

  10. Electric and magnetic field modulated energy dispersion, conductivity and optical response in double quantum wire with spin-orbit interactions

    Karaaslan, Y.; Gisi, B.; Sakiroglu, S.; Kasapoglu, E.; Sari, H.; Sokmen, I.

    2018-02-01

    We study the influence of electric field on the electronic energy band structure, zero-temperature ballistic conductivity and optical properties of double quantum wire. System described by double-well anharmonic confinement potential is exposed to a perpendicular magnetic field and Rashba and Dresselhaus spin-orbit interactions. Numerical results show up that the combined effects of internal and external agents cause the formation of crossing, anticrossing, camel-back/anomaly structures and the lateral, downward/upward shifts in the energy dispersion. The anomalies in the energy subbands give rise to the oscillation patterns in the ballistic conductance, and the energy shifts bring about the shift in the peak positions of optical absorption coefficients and refractive index changes.

  11. Transport, Optical, and Magnetic Properties of the Conducting Halide Perovskite CH 3NH 3SnI 3

    Mitzi, D. B.; Feild, C. A.; Schlesinger, Z.; Laibowitz, R. B.

    1995-01-01

    A low-temperature ( T ≤ 100°C) solution technique is described for the preparation of polycrystalline and single crystal samples of the conducting halide perovskite, CH 3NH 3SnI 3. Transport, Hall effect, magnetic, and optical properties are examined over the temperature range 1.8-300 K, confirming that this unusual conducting halide perovskite is a low carrier density p-type metal with a Hall hole density, 1/ RHe ≃ 2 × 10 19 cm -3. The resistivity of pressed pellet samples decreases with decreasing temperature with resistivity ratio ρ(300 K)/ρ(2 K) ≃ 3 and room temperature resistivity ρ(300 K) ≃ 7 mΩ-cm. A free-carrier infrared reflectivity spectrum with a plasma edge observed at approximately 1600 cm -1 further attests to the metallic nature of this compound and suggests a small optical effective mass, m* ≃ 0.2.

  12. Magnetic field dependence of conductivity and effective mass of carriers in a model of Mott-Hubbard material

    L.Didukh

    2005-01-01

    Full Text Available The effect of external magnetic field h on a static conductivity of Mott-Hubbard material which is described by the model with correlated hopping of electrons has been investigated. By means of canonical transformation, the effective Hamiltonian is obtained which takes into account strong intra-site Coulomb repulsion and correlated hopping. Using a variant of generalized Hartree-Fock approximation the single-electron Green function and quasiparticle energy spectrum of the model have been calculated. The static conductivity σ has been calculated as a function of h, electron concentration n and temperature T. The correlated hopping is shown to cause the electron-hole asymmetry of transport properties of narrow band materials.

  13. Heat conduction coefficient and coefficient of linear thermal expansion of electric insulation materials for superconducting magnetic system

    Deev, V.I.; Sobolev, V.P.; Kruglov, A.B.; Pridantsev, A.I.

    1984-01-01

    Results of experimental investigation of heat conduction coefficient and coefficient of linear thermal expansion and thermal shrinkages of the STEF-1 textolite-glass widely used in superconducting magnetic systems as electric insulating and structural material are presented. Samples of two types have been died: sample axisa is perpendicular to a plae of fiberglass layers ad sample axis is parallel to a plane of fiberglass layers. Heat conduction coefficient was decreased almost a five times with temperature decrease from 300 up to 5K and was slightly dependent on a sample type. Temperature variation of linear dimensions in a sample of the first type occurs in twice as fast as compared to the sample of the second type

  14. Nuclear magnetic resonance with dc SQUID [Super-conducting QUantum Interference Device] preamplifiers

    Fan, N.Q.; Heaney, M.B.; Clark, J.; Newitt, D.; Wald, L.; Hahn, E.L.; Bierlecki, A.; Pines, A.

    1988-08-01

    Sensitive radio-frequency (rf) amplifiers based on dc Superconducting QUantum Interface Devices (SQUIDS) are available for frequencies up to 200 MHz. At 4.2 K, the gain and noise temperature of a typical tuned amplifier are 18.6 +- 0.5 dB and 1.7 +- 0.5 K at 93 MHz. These amplifiers are being applied to a series of novel experiments on nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR). The high sensitivity of these amplifiers was demonstrated in the observation of ''nuclear spin noise'', the emission of photons by 35 Cl nuclei in a state of zero polarization. In the more conventional experiments in which one applies a large rf pulse to the spins, a Q-spoiler, consisting of a series array of Josephson junctions, is used to reduce the Q of the input circuit to a very low value during the pulse. The Q-spoiler enables the circuit to recover quickly after the pulse, and has been used in an NQR experiment to achieve a sensitivity of about 2 /times/ 10 16 nuclear Bohr magnetons in a single free precession signal with a bandwidth of 10 kHz. In a third experiment, a sample containing 35 Cl nuclei was placed in a capacitor and the signal detected electrically using a tuned SQUID amplifier and Q-spoiler. In this way, the electrical polarization induced by the precessing Cl nuclear quadrupole moments was detected: this is the inverse of the Stark effect in NQR. Two experiments involving NMR have been carried out. In the first, the 30 MHz resonance in 119 Sn nuclei is detected with a tuned amplifier and Q-spoiler, and a single pulse resolution of 10 18 nuclear Bohr magnetons in a bandwidth of 25 kHz has been achieved. For the second, a low frequency NMR system has been developed that uses an untuned input circuit coupled to the SQUID. The resonance in 195 Pt nuclei has been observed at 55 kHz in a field of 60 gauss. 23 refs., 11 figs

  15. Model for Generation of Neutrons in a Compact Diode with Laser-Plasma Anode and Suppression of Electron Conduction Using a Permanent Cylindrical Magnet

    Shikanov, A. E.; Vovchenko, E. D.; Kozlovskii, K. I.; Rashchikov, V. I.; Shatokhin, V. L.

    2018-04-01

    A model for acceleration of deuterons and generation of neutrons in a compact laser-plasma diode with electron isolation using magnetic field generated by a hollow cylindrical permanent magnet is presented. Experimental and computer-simulated neutron yields are compared for the diode structure under study. An accelerating neutron tube with a relatively high neutron generation efficiency can be constructed using suppression of electron conduction with the aid of a magnet placed in the vacuum volume.

  16. Radiation chemistry

    Rodgers, F.; Rodgers, M.A.

    1987-01-01

    The contents of this book include: Interaction of ionizing radiation with matter; Primary products in radiation chemistry; Theoretical aspects of radiation chemistry; Theories of the solvated electron; The radiation chemistry of gases; Radiation chemistry of colloidal aggregates; Radiation chemistry of the alkali halides; Radiation chemistry of polymers; Radiation chemistry of biopolymers; Radiation processing and sterilization; and Compound index

  17. Magnetic resonance imaging investigation of the bone conduction implant – a pilot study at 1.5 Tesla

    Fredén Jansson KJ

    2015-10-01

    Full Text Available Karl-Johan Fredén Jansson,1 Bo Håkansson,1 Sabine Reinfeldt,1 Cristina Rigato,1 Måns Eeg-Olofsson2 1Department of Signals and Systems, Chalmers University of Technology, 2Deptartment of Otorhinolaryngology Head and Neck Surgery, Sahlgrenska University Hospital, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden Purpose: The objective of this pilot study was to investigate if an active bone conduction implant (BCI used in an ongoing clinical study withstands magnetic resonance imaging (MRI of 1.5 Tesla. In particular, the MRI effects on maximum power output (MPO, total harmonic distortion (THD, and demagnetization were investigated. Implant activation and image artifacts were also evaluated.Methods and materials: One implant was placed on the head of a test person at the position corresponding to the normal position of an implanted BCI and applied with a static pressure using a bandage and scanned in a 1.5 Tesla MRI camera. Scanning was performed both with and without the implant, in three orthogonal planes, and for one spin-echo and one gradient-echo pulse sequence. Implant functionality was verified in-between the scans using an audio processor programmed to generate a sequence of tones when attached to the implant. Objective verification was also carried out by measuring MPO and THD on a skull simulator as well as retention force, before and after MRI.Results: It was found that the exposure of 1.5 Tesla MRI only had a minor effect on the MPO, ie, it decreased over all frequencies with an average of 1.1±2.1 dB. The THD remained unchanged above 300 Hz and was increased only at lower frequencies. The retention magnet was demagnetized by 5%. The maximum image artifacts reached a distance of 9 and 10 cm from the implant in the coronal plane for the spin-echo and the gradient-echo sequence, respectively. The test person reported no MRI induced sound from the implant.Conclusion: This pilot study indicates that the present BCI

  18. Cubic Dresselhaus interaction parameter from quantum corrections to the conductivity in the presence of an in-plane magnetic field

    Marinescu, D. C.

    2017-09-01

    We evaluate the quantum corrections to the conductivity of a two-dimensional electron system with competing Rashba (R) and linear and cubic Dresselhaus (D) spin-orbit interactions in the presence of an in-plane magnetic field B . Within a perturbative approximation, we investigate the interplay between the spin-orbit coupling and the magnetic field in determining the transport regime in two different limiting scenarios: when only one of the linear terms, either Rashba or Dresselhaus, dominates, and at equal linear couplings, when the cubic Dresselhaus breaks the spin symmetry. In each instance, we find that for B higher than a critical value, the antilocalization correction is suppressed and the effective dephasing time saturates to a constant value determined only by the spin-orbit interaction. At equal R-D linear couplings, this value is directly proportional with the cubic Dresselhaus contribution. In the same regime, the magnetoconductivity is expressed as a simple logarithmic function dependent only on the cubic Dresselhaus constant.

  19. Investigation of Parallel Radiofrequency Transmission for the Reduction of Heating in Long Conductive Leads in 3 Tesla Magnetic Resonance Imaging.

    Clare E McElcheran

    Full Text Available Deep Brain Stimulation (DBS is increasingly used to treat a variety of brain diseases by sending electrical impulses to deep brain nuclei through long, electrically conductive leads. Magnetic resonance imaging (MRI of patients pre- and post-implantation is desirable to target and position the implant, to evaluate possible side-effects and to examine DBS patients who have other health conditions. Although MRI is the preferred modality for pre-operative planning, MRI post-implantation is limited due to the risk of high local power deposition, and therefore tissue heating, at the tip of the lead. The localized power deposition arises from currents induced in the leads caused by coupling with the radiofrequency (RF transmission field during imaging. In the present work, parallel RF transmission (pTx is used to tailor the RF electric field to suppress coupling effects. Electromagnetic simulations were performed for three pTx coil configurations with 2, 4, and 8-elements, respectively. Optimal input voltages to minimize coupling, while maintaining RF magnetic field homogeneity, were determined for all configurations using a Nelder-Mead optimization algorithm. Resulting electric and magnetic fields were compared to that of a 16-rung birdcage coil. Experimental validation was performed with a custom-built 4-element pTx coil. In simulation, 95-99% reduction of the electric field at the tip of the lead was observed between the various pTx coil configurations and the birdcage coil. Maximal reduction in E-field was obtained with the 8-element pTx coil. Magnetic field homogeneity was comparable to the birdcage coil for the 4- and 8-element pTx configurations. In experiment, a temperature increase of 2±0.15°C was observed at the tip of the wire using the birdcage coil, whereas negligible increase (0.2±0.15°C was observed with the optimized pTx system. Although further research is required, these initial results suggest that the concept of optimizing p

  20. Investigation of Parallel Radiofrequency Transmission for the Reduction of Heating in Long Conductive Leads in 3 Tesla Magnetic Resonance Imaging.

    McElcheran, Clare E; Yang, Benson; Anderson, Kevan J T; Golenstani-Rad, Laleh; Graham, Simon J

    2015-01-01

    Deep Brain Stimulation (DBS) is increasingly used to treat a variety of brain diseases by sending electrical impulses to deep brain nuclei through long, electrically conductive leads. Magnetic resonance imaging (MRI) of patients pre- and post-implantation is desirable to target and position the implant, to evaluate possible side-effects and to examine DBS patients who have other health conditions. Although MRI is the preferred modality for pre-operative planning, MRI post-implantation is limited due to the risk of high local power deposition, and therefore tissue heating, at the tip of the lead. The localized power deposition arises from currents induced in the leads caused by coupling with the radiofrequency (RF) transmission field during imaging. In the present work, parallel RF transmission (pTx) is used to tailor the RF electric field to suppress coupling effects. Electromagnetic simulations were performed for three pTx coil configurations with 2, 4, and 8-elements, respectively. Optimal input voltages to minimize coupling, while maintaining RF magnetic field homogeneity, were determined for all configurations using a Nelder-Mead optimization algorithm. Resulting electric and magnetic fields were compared to that of a 16-rung birdcage coil. Experimental validation was performed with a custom-built 4-element pTx coil. In simulation, 95-99% reduction of the electric field at the tip of the lead was observed between the various pTx coil configurations and the birdcage coil. Maximal reduction in E-field was obtained with the 8-element pTx coil. Magnetic field homogeneity was comparable to the birdcage coil for the 4- and 8-element pTx configurations. In experiment, a temperature increase of 2±0.15°C was observed at the tip of the wire using the birdcage coil, whereas negligible increase (0.2±0.15°C) was observed with the optimized pTx system. Although further research is required, these initial results suggest that the concept of optimizing pTx to reduce DBS

  1. Influence of frequency of the excitation magnetic field and material's electric conductivity on domain wall dynamics in ferromagnetic materials

    Chávez-González, A.F. [Laboratorio de Evaluación No Destructiva Electromagnética (LENDE), ESIME-SEPI, Edif. Z-4, Instituto Politécnico Nacional, Zacatenco, México D.F., México (Mexico); Pérez-Benítez, J.A., E-mail: benitez_edl@yahoo.es [Laboratorio de Evaluación No Destructiva Electromagnética (LENDE), ESIME-SEPI, Edif. Z-4, Instituto Politécnico Nacional, Zacatenco, México D.F., México (Mexico); Espina-Hernández, J.H. [Laboratorio de Evaluación No Destructiva Electromagnética (LENDE), ESIME-SEPI, Edif. Z-4, Instituto Politécnico Nacional, Zacatenco, México D.F., México (Mexico); Grössinger, R. [Institute of Solid State Physics, Vienna University of Technology, Vienna (Austria); Hallen, J.M. [Departamento de Ingeniería Metalúrgica, ESIQIE, UPALM Edif. 7, Instituto Politécnico Nacional, Zacatenco, C.P. 07738, México D.F., México (Mexico)

    2016-03-01

    The present work analyzes the influence of electric conductivity on the Magnetic Barkhausen Noise (MBN) signal using a microscopic model which includes the influence of eddy currents. This model is also implemented to explain the dependence of MBN on the frequency of the applied magnetic field. The results presented in this work allow analyzing the influence of eddy currents on MBN signals for different values of the material's electric conductivity and for different frequencies of applied magnetic field. Additionally, the outcomes of this research can be used as a reference to differentiate the influence of eddy currents from that of second phase particles in the MBN signal, which has been reported in previous works. - Highlights: • Electromagnetic simulation of MBN with eddy currents and micro-magnetism. • Influence of applied field frequency on MBN is explained. • Influence of electric conductivity on MBN is analyzed. • Hysteresis losses in ferromagnetic materials is analyzed using the model.

  2. Thermal conductivity of layered organic superconductor β-(BDA-TTP)2SbF6 in a parallel magnetic field: Anomalous effect of coreless vortices

    Tanatar, M. A.; Ishiguro, T.; Toita, T.; Yamada, J.

    2005-01-01

    Thermal conductivity κ of the organic superconductor β-(BDA-TTP)2SbF6 was studied down to 0.3 K in magnetic fields H of varying orientation with respect to the superconducting plane. Anomalous plateau shape of the field dependence, κ vs H , is found for orientation of magnetic fields precisely parallel to the plane, in contrast to usual behavior observed in the perpendicular fields. We show that the lack of magnetic-field effect on the heat conduction results from coreless structure of vortices, causing both negligible scattering of phonons and constant in field electronic conduction up to the fields close to the upper critical field Hc2 . Usual behavior is recovered on approaching Hc2 and on slight field inclination from parallel direction, when normal cores are restored. This behavior points to the lack of bulk quasiparticle excitations induced by magnetic field, consistent with the conventional superconducting state.

  3. Magnetic resonance imaging investigation of the bone conduction implant – a pilot study at 1.5 Tesla

    Jansson, Karl-Johan Fredén; Håkansson, Bo; Reinfeldt, Sabine; Rigato, Cristina; Eeg-Olofsson, Måns

    2015-01-01

    Purpose The objective of this pilot study was to investigate if an active bone conduction implant (BCI) used in an ongoing clinical study withstands magnetic resonance imaging (MRI) of 1.5 Tesla. In particular, the MRI effects on maximum power output (MPO), total harmonic distortion (THD), and demagnetization were investigated. Implant activation and image artifacts were also evaluated. Methods and materials One implant was placed on the head of a test person at the position corresponding to the normal position of an implanted BCI and applied with a static pressure using a bandage and scanned in a 1.5 Tesla MRI camera. Scanning was performed both with and without the implant, in three orthogonal planes, and for one spin-echo and one gradient-echo pulse sequence. Implant functionality was verified in-between the scans using an audio processor programmed to generate a sequence of tones when attached to the implant. Objective verification was also carried out by measuring MPO and THD on a skull simulator as well as retention force, before and after MRI. Results It was found that the exposure of 1.5 Tesla MRI only had a minor effect on the MPO, ie, it decreased over all frequencies with an average of 1.1±2.1 dB. The THD remained unchanged above 300 Hz and was increased only at lower frequencies. The retention magnet was demagnetized by 5%. The maximum image artifacts reached a distance of 9 and 10 cm from the implant in the coronal plane for the spin-echo and the gradient-echo sequence, respectively. The test person reported no MRI induced sound from the implant. Conclusion This pilot study indicates that the present BCI may withstand 1.5 Tesla MRI with only minor effects on its performance. No MRI induced sound was reported, but the head image was highly distorted near the implant. PMID:26604836

  4. Magnetic resonance imaging investigation of the bone conduction implant - a pilot study at 1.5 Tesla.

    Jansson, Karl-Johan Fredén; Håkansson, Bo; Reinfeldt, Sabine; Rigato, Cristina; Eeg-Olofsson, Måns

    2015-01-01

    The objective of this pilot study was to investigate if an active bone conduction implant (BCI) used in an ongoing clinical study withstands magnetic resonance imaging (MRI) of 1.5 Tesla. In particular, the MRI effects on maximum power output (MPO), total harmonic distortion (THD), and demagnetization were investigated. Implant activation and image artifacts were also evaluated. One implant was placed on the head of a test person at the position corresponding to the normal position of an implanted BCI and applied with a static pressure using a bandage and scanned in a 1.5 Tesla MRI camera. Scanning was performed both with and without the implant, in three orthogonal planes, and for one spin-echo and one gradient-echo pulse sequence. Implant functionality was verified in-between the scans using an audio processor programmed to generate a sequence of tones when attached to the implant. Objective verification was also carried out by measuring MPO and THD on a skull simulator as well as retention force, before and after MRI. It was found that the exposure of 1.5 Tesla MRI only had a minor effect on the MPO, ie, it decreased over all frequencies with an average of 1.1±2.1 dB. The THD remained unchanged above 300 Hz and was increased only at lower frequencies. The retention magnet was demagnetized by 5%. The maximum image artifacts reached a distance of 9 and 10 cm from the implant in the coronal plane for the spin-echo and the gradient-echo sequence, respectively. The test person reported no MRI induced sound from the implant. This pilot study indicates that the present BCI may withstand 1.5 Tesla MRI with only minor effects on its performance. No MRI induced sound was reported, but the head image was highly distorted near the implant.

  5. Systems and methods for creation of conducting networks of magnetic particles through dynamic self-assembly process

    Snezhko, Oleksiy [Woodridge, IL; Aronson, Igor [Darien, IL; Kwok, Wai-Kwong [Downers Grove, IL

    2011-01-25

    Self-assembly of magnetic microparticles in AC magnetic fields. Excitation of the system by an AC magnetic field provides a variety of patterns that can be controlled by adjusting the frequency and the amplitude of the field. At low particle densities the low-frequency magnetic excitation favors cluster phase formation, while high frequency excitation favors chains and netlike structures. For denser configurations, an abrupt transition to the network phase was obtained.

  6. Diamond films deposited by oxygen-enhanced linear plasma chemistry

    Kromka, Alexander; Babchenko, Oleg; Ižák, Tibor; Varga, Marián; Davydova, Marina; Krátká, Marie; Rezek, Bohuslav

    2013-01-01

    Roč. 5, č. 6 (2013), s. 509-514 ISSN 2164-6627 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA ČR GAP108/12/0996 Institutional support: RVO:68378271 Keywords : diamond films * process gas chemistry * pulsed microwave plasma * surface conductivity of diamond Subject RIV: BM - Solid Matter Physics ; Magnetism

  7. Some device implications of voltage controlled magnetic anisotropy in Co/Gd2O3 thin films through REDOX chemistry

    Hao, Guanhua; Noviasky, Nicholas; Cao, Shi; Sabirianov, Ildar; Yin, Yuewei; Ilie, Carolina C.; Kirianov, Eugene; Sharma, Nishtha; Sokolov, Andrei; Marshall, Andrew; Xu, Xiaoshan; Dowben, Peter A.

    2018-04-01

    The effect of intermediate interfacial oxidation on the in-plane magnetization of multilayer stack Pt/Co/Gd2O3, on a p-type silicon substrate, has been investigated by magneto-optical Kerr effect (MOKE) measurements, the anomalous Hall effect, and magnetoresistance measurements. While voltage controlled perpendicular magnetic anisotropy of a metal/oxide heterostructure is known, this heterostructure displays an inverse relationship between voltage and coercivity. The anomalous Hall effect demonstrates a significant change in hysteresis, with the applied bias sign. There is a higher perpendicular magnetic anisotropy with positive bias exposure.

  8. Magnetism of Nanographene-Based Microporous Carbon and Its Applications: Interplay of Edge Geometry and Chemistry Details in the Edge State

    Enoki, Toshiaki; Kiguchi, Manabu

    2018-03-01

    This paper is a contribution to the Physical Review Applied collection in memory of Mildred S. Dresselhaus. Nanographenes have important edge geometry dependence in their electronic structures. In armchair edges, electron wave interference works to contribute to energetic stability. Meanwhile, zigzag edges possess an edge-localized and spin-polarized nonbonding edge state, which causes electronic, magnetic, and chemical activities. In addition to the geometry dependence, the electronic structures are seriously affected by edge chemistry details. The edge chemistry dependence together with edge geometries on the electronic structures are discussed with samples of randomly networked nanographenes (microporous activated carbon fibers) in pristine state and under high-temperature annealing. In the pristine sample with the edges oxidized in ambient atmospheric conditions, the edge state, which is otherwise unstable, can be stabilized because of the charge transfer from nanographene to terminating oxygen. Nanographene, whose edges consist of a combination of magnetic zigzag edges and nonmagnetic armchair edges, is found to be ferrimagnetic with a nonzero net magnetic moment created under the interplay between a strong intrazigzag-edge ferromagnetic interaction and intermediate-strength interzigzag-edge antiferromagnetic-ferromagnetic interaction. At heat-treatment temperatures just below the fusion start (approximately 1500 K), the edge-terminating structure is changed from oxygen-containing groups to hydrogen in the nanographene network. Additionally, hydrogen-terminated zigzag edges, which are present as the majority and chemically unstable, play a triggering role in fusion above 1500 K. The fusion start brings about an insulator-to-metal transition at TI -M˜1500 K . Local fusions taking place percolatively between nanographenes work to expand the π -bond network, eventually resulting in the development of antiferromagnetic short-range order toward spin glass in the

  9. Magnetical and optical properties of nanodiamonds can be tuned by particles surface chemistry: theoretical and experimental study

    Kratochvílová, Irena; Šebera, Jakub; Ashcheulov, Petr; Golan, Martin; Ledvina, Miroslav; Mičová, Júlia; Mravec, F.; Kovalenko, A.; Zverev, D.; Yavkin, B.; Orlinskii, S.; Záliš, Stanislav; Fišerová, Anna; Richter, Jan; Šefc, L.; Turánek, J.

    2014-01-01

    Roč. 118, č. 43 (2014), s. 25245-25252 ISSN 1932-7447 R&D Projects: GA TA ČR TA01011165; GA ČR(CZ) GA14-10279S Institutional support: RVO:68378271 ; RVO:61388971 ; RVO:61388963 ; RVO:61388955 Keywords : nanodiamond particles * NV luminescent centers * surface functionalization * DFT Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.772, year: 2014

  10. Feedback first: the surprisingly weak effects of magnetic fields, viscosity, conduction and metal diffusion on sub-L* galaxy formation

    Su, Kung-Yi; Hopkins, Philip F.; Hayward, Christopher C.; Faucher-Giguère, Claude-André; Kereš, Dušan; Ma, Xiangcheng; Robles, Victor H.

    2017-10-01

    Using high-resolution simulations with explicit treatment of stellar feedback physics based on the FIRE (Feedback In Realistic Environments) project, we study how galaxy formation and the interstellar medium (ISM) are affected by magnetic fields, anisotropic Spitzer-Braginskii conduction and viscosity, and sub-grid metal diffusion from unresolved turbulence. We consider controlled simulations of isolated (non-cosmological) galaxies but also a limited set of cosmological 'zoom-in' simulations. Although simulations have shown significant effects from these physics with weak or absent stellar feedback, the effects are much weaker than those of stellar feedback when the latter is modelled explicitly. The additional physics have no systematic effect on galactic star formation rates (SFRs). In contrast, removing stellar feedback leads to SFRs being overpredicted by factors of ˜10-100. Without feedback, neither galactic winds nor volume-filling hot-phase gas exist, and discs tend to runaway collapse to ultra-thin scaleheights with unphysically dense clumps congregating at the galactic centre. With stellar feedback, a multi-phase, turbulent medium with galactic fountains and winds is established. At currently achievable resolutions and for the investigated halo mass range 1010-1013 M⊙, the additional physics investigated here (magnetohydrodynamic, conduction, viscosity, metal diffusion) have only weak (˜10 per cent-level) effects on regulating SFR and altering the balance of phases, outflows or the energy in ISM turbulence, consistent with simple equipartition arguments. We conclude that galactic star formation and the ISM are primarily governed by a combination of turbulence, gravitational instabilities and feedback. We add the caveat that active galactic nucleus feedback is not included in the present work.

  11. Behavior of conducting solid or liquid jet moving in magnetic field: (1) paraxial; (2) transverse; (3) oblique

    Weggel, R.J.

    1998-06-01

    When a conductor moves through a nonuniform magnetic field, eddy currents flow that interact with the field to decelerate the conductor and perhaps change its trajectory, orientation and, if a liquid, shape. A rod of radius a 1 cm and the density and electrical conductivity of melted gallium (γ 6.1 g/cm 3 , ρ = 26 microΩ cm) will decelerate 6.3 m/s in a 0.5 m ramp of paraxial field with a constant gradient g of 40 T/m (ΔB = 20 T). The deceleration is proportional to a 2 gΔB/γρ, independent of the velocity. The bar decelerates about twice as much in a 20 T, 0.5 m ramp of transverse field. A bar traveling at a shallow angle to such a field decelerates about 6.3 m/s. If the bar is 0.25 m long and moves at 20 m/s, it aligns with the field in ∼10 ms, during which time it advances ∼0.2 m

  12. Effects of Anisotropic Thermal Conductivity and Lorentz Force on the Flow and Heat Transfer of a Ferro-Nanofluid in a Magnetic Field

    Yubai Li

    2017-07-01

    Full Text Available In this paper, we study the effects of the Lorentz force and the induced anisotropic thermal conductivity due to a magnetic field on the flow and the heat transfer of a ferro-nanofluid. The ferro-nanofluid is modeled as a single-phase fluid, where the viscosity depends on the concentration of nanoparticles; the thermal conductivity shows anisotropy due to the presence of the nanoparticles and the external magnetic field. The anisotropic thermal conductivity tensor, which depends on the angle of the applied magnetic field, is suggested considering the principle of material frame indifference according to Continuum Mechanics. We study two benchmark problems: the heat conduction between two concentric cylinders as well as the unsteady flow and heat transfer in a rectangular channel with three heated inner cylinders. The governing equations are made dimensionless, and the flow and the heat transfer characteristics of the ferro-nanofluid with different angles of the magnetic field, Hartmann number, Reynolds number and nanoparticles concentration are investigated systematically. The results indicate that the temperature field is strongly influenced by the anisotropic behavior of the nanofluids. In addition, the magnetic field may enhance or deteriorate the heat transfer performance (i.e., the time-spatially averaged Nusselt number in the rectangular channel depending on the situations.

  13. Effect of a uniform magnetic induction field upon the flow of an electrically conducting fluid placed in a straight rectangular cross section, one of the walls of which, characterized by an infinite conductivity, presents uniform translation movement

    Herve, Patrick

    1975-01-01

    This is a theoretical study of an electrically viscous fluid flowing in a straight rectangular cross section channel, a wall of which, infinitely conducting, is placed perpendicularly to the direction of a uniform magnetic induction field. The three other walls of the channel being electrically insulating, remain motionless. Formulas giving velocity distribution law in the straight section of the flow in relation to the Hartmann's number, curves illustrating the accelerating effect produced across the whole section, by the application of the magnetic induction field, and example for the distribution of the electric current lines in case of a square section are given [fr

  14. Erroneous Magnet Positioning Leads to Failure of Inhibition of Inappropriate Shock during Fast Conducting Atrial Fibrillation Episodes.

    Römers, Hans; VAN Dijk, Vincent; Balt, Jippe

    2017-06-01

    We present the case of a 75-year-old patient with a single-chamber St. Jude Medical internal cardioverter defibrillator (ICD; St. Jude Medical, St. Paul, MN, USA) for primary prevention, who was admitted with 39 inappropriate ICD shocks because of atrial fibrillation with rapid ventricular frequention, despite magnet placement. Review of the device manual and literature revealed that apart from different responses to magnet placement programmed for the various manufacturers, the type of magnet and the positioning can be of specific interest. In the case presented, the donut-shaped magnet should have been placed off-center instead of directly over the device. © 2017 Wiley Periodicals, Inc.

  15. Spin polarization and magnetization of conduction-band dilute-magnetic-semiconductor quantum wells with non-step-like density of states

    Simserides, Constantinos

    2005-01-01

    We study the magnetization, M, and the spin polarization, ζ, of n-doped non-magnetic-semiconductor (NMS)/narrow to wide dilute-magnetic-semiconductor (DMS)/n-doped NMS quantum wells, as a function of the temperature, T, and the in-plane magnetic field, B. Under such conditions the density of states (DOS) deviates from the occasionally stereotypic step-like form, both quantitatively and qualitatively. The DOS modification causes an impressive fluctuation of M in cases of vigorous competition between spatial and magnetic confinement. At low T, the enhanced electron spin-splitting, U oσ , acquires its bigger value. At higher T, U oσ decreases, augmenting the influence of the spin-up electrons. Increasing B, U oσ increases and accordingly electrons populate spin-down subbands while they abandon spin-up subbands. Furthermore, due to the DOS modification, all energetically higher subbands become gradually depopulated

  16. Bad chemistry

    Petsko, Gregory A

    2004-01-01

    General chemistry courses haven't changed significantly in forty years. Because most basic chemistry students are premedical students, medical schools have enormous influence and could help us start all over again to create undergraduate chemistry education that works.

  17. Effect of high-frequency repetitive transcranial magnetic stimulation on motor cortical excitability and sensory nerve conduction velocity in subacute-stage incomplete spinal cord injury patients.

    Cha, Hyun Gyu; Ji, Sang-Goo; Kim, Myoung-Kwon

    2016-07-01

    [Purpose] The aim of the present study was to determine whether repetitive transcranial magnetic stimulation can improve sensory recovery of the lower extremities in subacute-stage spinal cord injury patients. [Subjects and Methods] This study was conducted on 20 subjects with diagnosed paraplegia due to spinal cord injury. These 20 subjects were allocated to an experimental group of 10 subjects that underwent active repetitive transcranial magnetic stimulation or to a control group of 10 subjects that underwent sham repetitive transcranial magnetic stimulation. The SCI patients in the experimental group underwent active repetitive transcranial magnetic stimulation and conventional rehabilitation therapy, whereas the spinal cord injury patients in the control group underwent sham repetitive transcranial magnetic stimulation and conventional rehabilitation therapy. Participants in both groups received therapy five days per week for six-weeks. Latency, amplitude, and sensory nerve conduction velocity were assessed before and after the six week therapy period. [Results] A significant intergroup difference was observed for posttreatment velocity gains, but no significant intergroup difference was observed for amplitude or latency. [Conclusion] repetitive transcranial magnetic stimulation may be improve sensory recovery of the lower extremities in subacute-stage spinal cord injury patients.

  18. Conceptual designs of conduction cooled MgB2 magnets for 1.5 and 3.0T full body MRI systems

    Baig, Tanvir; Al Amin, Abdullah; Deissler, Robert J; Sabri, Laith; Poole, Charles; Brown, Robert W; Tomsic, Michael; Doll, David; Rindfleisch, Matthew; Peng, Xuan; Mendris, Robert; Akkus, Ozan; Sumption, Michael; Martens, Michael

    2017-01-01

    Conceptual designs of 1.5 and 3.0 T full-body magnetic resonance imaging (MRI) magnets using conduction cooled MgB2 superconductor are presented. The sizes, locations, and number of turns in the eight coil bundles are determined using optimization methods that minimize the amount of superconducting wire and produce magnetic fields with an inhomogeneity of less than 10 ppm over a 45 cm diameter spherical volume. MgB2 superconducting wire is assessed in terms of the transport, thermal, and mechanical properties for these magnet designs. Careful calculations of the normal zone propagation velocity and minimum quench energies provide support for the necessity of active quench protection instead of passive protection for medium temperature superconductors such as MgB2. A new ‘active’ protection scheme for medium Tc based MRI magnets is presented and simulations demonstrate that the magnet can be protected. Recent progress on persistent joints for multifilamentary MgB2 wire is presented. Finite difference calculations of the quench propagation and temperature rise during a quench conclude that active intervention is needed to reduce the temperature rise in the coil bundles and prevent damage to the superconductor. Comprehensive multiphysics and multiscale analytical and finite element analysis of the mechanical stress and strain in the MgB2 wire and epoxy for these designs are presented for the first time. From mechanical and thermal analysis of our designs we conclude there would be no damage to such a magnet during the manufacturing or operating stages, and that the magnet would survive various quench scenarios. This comprehensive set of magnet design considerations and analyses demonstrate the overall viability of 1.5 and 3.0 T MgB2 magnet designs. PMID:29170604

  19. The Use and Evaluation of Scaffolding, Student Centered-Learning, Behaviorism, and Constructivism to Teach Nuclear Magnetic Resonance and IR Spectroscopy in a Two-Semester Organic Chemistry Course

    Livengood, Kimberly; Lewallen, Denver W.; Leatherman, Jennifer; Maxwell, Janet L.

    2012-01-01

    Since 2002, infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) spectrometry have been introduced at the beginning of the first-semester organic chemistry lab course at this university. Starting in 2008, each individual student was given 20 unique homework problems that consisted of multiple-choice [superscript 1]H NMR and IR problems…

  20. Magnetic studies of current conduction and flux pinning in high-Tc cuprates: Virgin, irradiated, and oxygen deficient materials

    Thompson, J.R.; Civale, L.; Marwick, A.D.; Holtzberg, F.

    1992-09-01

    To increase the current density and pinning of magnetic flux in high temperature superconductors, defects with point-like and line-like geometries were created in controlled numbers using ion irradiation methods. Single crystals of Y 1 Ba 2 Cu 3 O 7 and Bi 2 Sr 2 Ca 1 Cu 2 0 8 superconductors were studied using dc magnetic methods. These studies showed greatly increased irreversibility in the vortex state magnetization and enhanced intragrain current density J c following irradiation. Linear defects, created by irradiation with energetic heavy ions, are particularly effective in pinning vortices at higher temperatures and magnetic fields. Further investigations of ''flux creep'' (the time dependence of magnetization) are well described by recent vortex glass and collective pinning theories. Complementary investigations have delineated the role of oxygen deficiency δ on pinning in aligned Y 1 Ba 2 Cu 3 O 7-δ materials

  1. Magnets

    Young, I.R.

    1984-01-01

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

  2. A planar conducting micro-loop structure for transportation of magnetic beads: An approach towards rapid sensing and quantification of biological entities

    Gooneratne, Chinthaka Pasan

    2012-03-01

    Magnetic beads are utilized effectively in a wide variety of medical applications due to their small size, biocompatibility and large surface to volume ratio. Microfluidic lab-on-a-chip (LOC) devices, which utilize magnetic beads, are promising tools for accurate and rapid cell sorting and counting. Effective manipulation of beads is a critical factor for the performance of LOC devices. In this paper we propose a planar conducting micro-loop structure to trap, manipulate and transport magnetic beads. Current through the micro-loops produces magnetic field gradients that are proportional to the force required to manipulate the beads. Numerical analyses were performed to study the magnetic forces and their spatial distributions. Experimental results showed that magnetic beads could not only be transported towards a target region, e.g., for sensing purposes, but also the trapping rate could be increased by switching current between the different loops in the micro-loop structure. This method could lead to rapid and accurate quantification of biological entities tagged with magnetic beads. Copyright © 2012 American Scientific Publishers. All rights reserved.

  3. A planar conducting micro-loop structure for transportation of magnetic beads: An approach towards rapid sensing and quantification of biological entities

    Gooneratne, Chinthaka Pasan; Giouroudi, Ioanna; Kosel, Jü rgen

    2012-01-01

    tools for accurate and rapid cell sorting and counting. Effective manipulation of beads is a critical factor for the performance of LOC devices. In this paper we propose a planar conducting micro-loop structure to trap, manipulate and transport magnetic

  4. Development of the active magnetic regenerative refrigerator operating between 77 K and 20 K with the conduction cooled high temperature superconducting magnet

    Park, Inmyong; Jeong, Sangkwon

    2017-12-01

    The experimental investigation of an active magnetic regenerative refrigerator (AMRR) operating between 77 K and 20 K is discussed in this paper, with detailed energy transfer analysis. A multi-layered active magnetic regenerator (AMR) is used, which consists of four different rare earth intermetallic compounds in the form of irregular powder. Numerical simulation confirms that the AMR can attain its target operating temperature range. Magnetic field alternation throughout the AMR is generated by a high temperature superconducting (HTS) magnet. The HTS magnet is cooled by a two stage Gifford-McMahon (GM) cryocooler. Helium gas was employed as a working fluid and its oscillating flow in the AMR is controlled in accordance with the magnetic field variation. The AMR is divided into two stages and each stage has a different mass flow rate as needed to achieve the desired cooling performance. The temperature variation of the AMR during the experiment is monitored by temperature sensors installed inside the AMR. The experimental results show that the AMRR is capable of achieving no-load temperature of 25.4 K while the warm end temperature is 77 K. The performance of the AMRR is analyzed by observing internal temperature variations at cyclic steady state. Furthermore, numerical estimation of the cooling capacity and the temperature variation of the AMR are examined and compared with the experimental results.

  5. Structural chemistry and magnetic properties of Pr3-xSr1+xCrNiO8

    Dutton, Sian E.; Bahout, Mona; Battle, Peter D.; Tonus, Florent; Demange, Valerie

    2008-01-01

    Polycrystalline samples of the n=1 Ruddlesden-Popper system Pr 3-x Sr 1+x CrNiO 8 have been synthesized over the composition range 0.0 0.1 adopt the tetragonal space group I4/mmm; Pr 2.9 Sr 1.1 CrNiO 8 adopts the orthorhombic space group Fmmm. There is no evidence of Cr/Ni cation ordering in any composition. A maximum in the zero-field cooled magnetic susceptibility is observed at a temperature T f that decreases with increasing Sr content; 52≤T f (K)≤13. The frequency dependence of T f observed in a.c. susceptibility measurements, together with the analysis of neutron diffraction data, suggests that the atomic magnetic moments in these compositions adopt a spin-glass-like state below T f . - Graphical abstract: The n=1 Ruddlesden-Popper system Pr 3-x Sr 1+x CrNiO 8 (0.0< x≤1.0) has been characterized by diffraction methods and magnetometry. There is no evidence of Cr/Ni cation ordering in any composition. The atomic magnetic moments adopt a spin-glass-like state below a transition temperature that decreases from 52 K (x=0.1) to 13 K (x=1.0)

  6. Complex chemistry

    Kim, Bong Gon; Kim, Jae Sang; Kim, Jin Eun; Lee, Boo Yeon

    2006-06-01

    This book introduces complex chemistry with ten chapters, which include development of complex chemistry on history coordination theory and Warner's coordination theory and new development of complex chemistry, nomenclature on complex with conception and define, chemical formula on coordination compound, symbol of stereochemistry, stereo structure and isomerism, electron structure and bond theory on complex, structure of complex like NMR and XAFS, balance and reaction on solution, an organo-metallic chemistry, biology inorganic chemistry, material chemistry of complex, design of complex and calculation chemistry.

  7. Global solvability, non-resistive limit and magnetic boundary layer of the compressible heat-conductive MHD equations

    Zhang, Jianwen; Zhao, Xiaokui

    2015-01-01

    In general, the resistivity is inversely proportional to the electrical conductivity, and is usually taken to be zero when the conducting fluid is of extremely high conductivity (e.g., ideal conductors). In this paper, we first establish the global well-posedness of strong solution to an initial-boundary value problem of the one-dimensional compressible, viscous, heat-conductive, non-resistive MHD equations with general heat-conductivity coefficient and large data. Then, the non-resistive lim...

  8. Mathematical Chemistry

    Trinajstić, Nenad; Gutman, Ivan

    2002-01-01

    A brief description is given of the historical development of mathematics and chemistry. A path leading to the meeting of these two sciences is described. An attempt is made to define mathematical chemistry, and journals containing the term mathematical chemistry in their titles are noted. In conclusion, the statement is made that although chemistry is an experimental science aimed at preparing new compounds and materials, mathematics is very useful in chemistry, among other things, to produc...

  9. Evolution of the magnetic properties of Co10Cu90 nanoparticles prepared by wet chemistry with thermal annealing.

    García, I; Echeberria, J; Kakazei, G N; Golub, V O; Saliuk, O Y; Ilyn, M; Guslienko, K Y; González, J M

    2012-09-01

    Nanoparticles of Co10Cu90 alloy have been prepared by sonochemical wet method. According to transmission electron microscopy, bimetallic particles with typical diameter of 50-100 nm consisting of nanocrystallites with average diameter of 15-20 nm were obtained. The samples were annealed at 300 degrees C and 450 degrees C. Zero field cooled and field cooled temperature dependences of magnetization in the temperature range of 5-400 K at 50 Oe, as well as magnetization hysteresis loops at 15, 100 and 305 K were measured by vibrating sample magnetometry. Presence of antiferromagnetic phase, most probably of the oxide Co3O4, was observed in as-prepared sample. The lowest coercivity was found for the CoCu sample annealed at-300 degrees C, whereas for as prepared sample and the one annealed at 450 degrees C it was significantly higher. The samples were additionally probed by continuous wave ferromagnetic resonance at room, temperature using a standard X-band electron spin resonance spectrometer. A good correspondence between evolution of the coercivity and the microwave resonance fields with annealing temperature was observed.

  10. Magnetic field generation by pointwise zero-helicity three-dimensional steady flow of an incompressible electrically conducting fluid

    Rasskazov, Andrey; Chertovskih, Roman; Zheligovsky, Vladislav

    2018-04-01

    We introduce six families of three-dimensional space-periodic steady solenoidal flows, whose kinetic helicity density is zero at any point. Four families are analytically defined. Flows in four families have zero helicity spectrum. Sample flows from five families are used to demonstrate numerically that neither zero kinetic helicity density nor zero helicity spectrum prohibit generation of large-scale magnetic field by the two most prominent dynamo mechanisms: the magnetic α -effect and negative eddy diffusivity. Our computations also attest that such flows often generate small-scale field for sufficiently small magnetic molecular diffusivity. These findings indicate that kinetic helicity and helicity spectrum are not the quantities controlling the dynamo properties of a flow regardless of whether scale separation is present or not.

  11. Quantum corrections to conductivity observed at intermediate magnetic fields in a high mobility GaAs/AlGaAs 2-dimensional electron gas

    Taboryski, R.; Veje, E.; Lindelof, P.E.

    1990-01-01

    Magnetoresistance with the field perpendicular to the 2-dimensional electron gas in a high mobility GaAs/AlGaAs heterostructure at low temperatures is studied. At the lowest magnetic field we observe the weak localization. At magnetic fields, where the product of the mobility and the magnetic field is of the order of unity, the quantum correction to conductivity due to the electron-electron interaction is as a source of magnetoresistance. A consistent analysis of experiments in this regime is for the first time performed. In addition to the well known electron-electron term with the expected temperature dependence, we find a new type of temperature independent quantum correction, which varies logarithmically with mobility. (orig.)

  12. Experimental evaluation of electrical conductivity imaging of anisotropic brain tissues using a combination of diffusion tensor imaging and magnetic resonance electrical impedance tomography

    Sajib, Saurav Z. K.; Jeong, Woo Chul; Oh, Tong In; Kim, Hyung Joong, E-mail: bmekim@khu.ac.kr, E-mail: ejwoo@khu.ac.kr; Woo, Eung Je, E-mail: bmekim@khu.ac.kr, E-mail: ejwoo@khu.ac.kr [Department of Biomedical Engineering, Kyung Hee University, Seoul 02447 (Korea, Republic of); Kyung, Eun Jung [Department of Pharmacology, Chung-Ang University, Seoul 06974 (Korea, Republic of); Kim, Hyun Bum [Department of East-West Medical Science, Kyung Hee University, Yongin 17104 (Korea, Republic of); Kwon, Oh In [Department of Mathematics, Konkuk University, Seoul 05029 (Korea, Republic of)

    2016-06-15

    Anisotropy of biological tissues is a low-frequency phenomenon that is associated with the function and structure of cell membranes. Imaging of anisotropic conductivity has potential for the analysis of interactions between electromagnetic fields and biological systems, such as the prediction of current pathways in electrical stimulation therapy. To improve application to the clinical environment, precise approaches are required to understand the exact responses inside the human body subjected to the stimulated currents. In this study, we experimentally evaluate the anisotropic conductivity tensor distribution of canine brain tissues, using a recently developed diffusion tensor-magnetic resonance electrical impedance tomography method. At low frequency, electrical conductivity of the biological tissues can be expressed as a product of the mobility and concentration of ions in the extracellular space. From diffusion tensor images of the brain, we can obtain directional information on diffusive movements of water molecules, which correspond to the mobility of ions. The position dependent scale factor, which provides information on ion concentration, was successfully calculated from the magnetic flux density, to obtain the equivalent conductivity tensor. By combining the information from both techniques, we can finally reconstruct the anisotropic conductivity tensor images of brain tissues. The reconstructed conductivity images better demonstrate the enhanced signal intensity in strongly anisotropic brain regions, compared with those resulting from previous methods using a global scale factor.

  13. Magnetism and structural chemistry of the n=2 Ruddlesden-Popper phase La3LiMnO7

    Battle, Peter D.; Burley, Jonathan C.; Gallon, Daniel J.; Grey, Clare P.; Sloan, Jeremy

    2004-01-01

    Polycrystalline samples of the n=2 Ruddlesden-Popper phase La 3 LiMnO 7 have been prepared and characterized. X-ray and neutron diffraction suggest that the structure is tetragonal with a disordered distribution of Li and Mn cations over the octahedral sites, but 6 Li MAS NMR shows that the Li and Mn are 1:1 ordered locally. Electron microscopy shows that the stacking of the cation-ordered, perovskite-like bilayers along the crystallographic z-axis is disordered on the distance scale sampled by X-ray and neutron diffraction. Magnetometry data and neutron diffraction data collected at 2 K together suggest that the Mn cations within each structural domain order antiferromagnetically at 14 K, but that the disorder along z prevents the establishment of long-range magnetic order

  14. Anisotropic universal conductance fluctuations in disordered quantum wires with Rashba and Dresselhaus spin–orbit interaction and an applied in-plane magnetic field

    Scheid, Matthias; Adagideli, İnanç; Richter, Klaus; Nitta, Junsaku

    2009-01-01

    We investigate the transport properties of narrow quantum wires realized in disordered two-dimensional electron gases in the presence of k-linear Rashba and Dresselhaus spin–orbit interaction, and an applied in-plane magnetic field. Building on previous work (Scheid et al 2008 Phys. Rev. Lett. 101 266401), we find that in addition to the conductance, the universal conductance fluctuations also feature anisotropy with respect to the magnetic field direction. This anisotropy can be explained solely from the symmetries exhibited by the Hamiltonian as well as the relative strengths of the Rashba and Dresselhaus spin–orbit interaction and thus can be utilized to detect this ratio from purely electrical measurements

  15. Radio frequency self-resonant coil for contactless AC-conductivity in 100 T class ultra-strong pulse magnetic fields

    Nakamura, D.; Altarawneh, M. M.; Takeyama, S.

    2018-03-01

    A contactless measurement system of electrical conductivity was developed for application under pulsed high magnetic fields over 100 T by using a self-resonant-type, high-frequency circuit. Electromagnetic fields in the circuit were numerically analysed by the finite element method, to show how the resonant power spectra of the circuit depends on the electrical conductivity of a sample set on the probe-coil. The performance was examined using a high-temperature cuprate superconductor, La2-x Sr x CuO4, in magnetic fields up to 102 T with a high frequency of close to 800 MHz. As a result, the upper critical field could be determined with a good signal-to-noise ratio.

  16. On the flow of an electrically conducting gas past a slender body of revolution placed in a circular wind tunnel in the presence of a crossed magnetic field

    Suwa, Shigeaki; Kusukawa, Ken-ichi.

    1976-01-01

    The wind tunnel interference problem in magnetohydrodynamics, in which an inviscid compressible fluid with small electrical conductivity flows steadily past a slender axi-symmetric pointed body of revolution placed in a cylindrical perfectly insulated wind tunnel, in the presence of a crossed magnetic field, is considered. Using the analytical method which was studied by one of the present authors, the streamlines and the space charge in a cross section are calculated. (auth.)

  17. K[subscript a] and K[subscript b] from pH and Conductivity Measurements: A General Chemistry Laboratory Exercise

    Nyasulu, Frazier; Moehring, Michael; Arthasery, Phyllis; Barlag, Rebecca

    2011-01-01

    The acid ionization constant, K[subscript a], of acetic acid and the base ionization constant, K[subscript b], of ammonia are determined easily and rapidly using a datalogger, a pH sensor, and a conductivity sensor. To decrease sample preparation time and to minimize waste, sequential aliquots of a concentrated standard are added to a known volume…

  18. Conductance enhancement due to interface magnons in electron-beam evaporated MgO magnetic tunnel junctions with CoFeB free layer deposited at different pressure

    Guo, P.; Yu, G. Q.; Wei, H. X.; Han, X. F., E-mail: jiafengfeng@aphy.iphy.ac.cn, E-mail: xfhan@aphy.iphy.ac.cn [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Li, D. L.; Feng, J. F., E-mail: jiafengfeng@aphy.iphy.ac.cn, E-mail: xfhan@aphy.iphy.ac.cn [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); CRANN and School of Physics, Trinity College, Dublin 2 (Ireland); Kurt, H. [CRANN and School of Physics, Trinity College, Dublin 2 (Ireland); Department of Engineering Physics, Istanbul Medeniyet University, 34720 Istanbul (Turkey); Chen, J. Y.; Coey, J. M. D. [CRANN and School of Physics, Trinity College, Dublin 2 (Ireland)

    2014-10-21

    Electron-beam evaporated MgO-based magnetic tunnel junctions have been fabricated with the CoFeB free layer deposited at Ar pressure from 1 to 4 mTorr, and their tunneling process has been studied as a function of temperature and bias voltage. By changing the growth pressure, the junction dynamic conductance dI/dV, inelastic electron tunneling spectrum d²I/dV², and tunneling magnetoresistance vary with temperature. Moreover, the low-energy magnon cutoff energy E{sub C} derived from the conductance versus temperature curve agrees with interface magnon energy obtained directly from the inelastic electron tunneling spectrum, which demonstrates that interface magnons are involved in the electron tunneling process, opening an additional conductance channel and thus enhancing the total conductance.

  19. Longitudinal conductivity and transverse charge redistribution in coupled quantum wells subject to in-plane magnetic fields

    Kolorenč, Jindřich; Smrčka, Ludvík; Středa, Pavel

    2002-01-01

    Roč. 12, - (2002), s. 311-314 ISSN 1386-9477 R&D Projects: GA ČR GA202/01/0754; GA ČR GA202/01/0764 Institutional research plan: CEZ:AV0Z1010914 Keywords : double - layer two-dimensional electron system * magnetotransort * Hall effect Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.107, year: 2002

  20. Chemistry Notes

    School Science Review, 1976

    1976-01-01

    Described are eight chemistry experiments and demonstrations applicable to introductory chemistry courses. Activities include: measure of lattice enthalpy, Le Chatelier's principle, decarboxylation of soap, use of pocket calculators in pH measurement, and making nylon. (SL)

  1. Chemistry Dashboard

    The Chemistry Dashboard is part of a suite of dashboards developed by EPA to help evaluate the safety of chemicals. The Chemistry Dashboard provides access to a variety of information on over 700,000 chemicals currently in use.

  2. Combinatorial chemistry

    Nielsen, John

    1994-01-01

    An overview of combinatorial chemistry is presented. Combinatorial chemistry, sometimes referred to as `irrational drug design,' involves the generation of molecular diversity. The resulting chemical library is then screened for biologically active compounds.......An overview of combinatorial chemistry is presented. Combinatorial chemistry, sometimes referred to as `irrational drug design,' involves the generation of molecular diversity. The resulting chemical library is then screened for biologically active compounds....

  3. Aquatic Chemistry

    Kim, Dong Yeun; Kim, Oh Sik; Kim, Chang Guk; Park, Cheong Gil; Lee, Gwi Hyeon; Lee, Cheol Hui

    1987-07-01

    This book deals aquatic chemistry, which treats water and environment, chemical kinetics, chemical balance like dynamical characteristic, and thermodynamics, acid-base chemistry such as summary, definition, kinetics, and PH design for mixture of acid-base chemistry, complex chemistry with definition, and kinetics, precipitation and dissolution on summary, kinetics of precipitation and dissolution, and balance design oxidation and resolution with summary, balance of oxidation and resolution.

  4. Positronium chemistry

    Green, James

    1964-01-01

    Positronium Chemistry focuses on the methodologies, reactions, processes, and transformations involved in positronium chemistry. The publication first offers information on positrons and positronium and experimental methods, including mesonic atoms, angular correlation measurements, annihilation spectra, and statistical errors in delayed coincidence measurements. The text then ponders on positrons in gases and solids. The manuscript takes a look at the theoretical chemistry of positronium and positronium chemistry in gases. Topics include quenching, annihilation spectrum, delayed coincidence

  5. The electrical conductivity of the upper mantle and lithosphere from the magnetic signal due to ocean tidal flow

    Schnepf, Neesha Regmi; Kuvshinov, Alexey; Grayver, Alexander

    galvanically with Earth’s lithosphere (i.e. by direct coupling of the source currents in the ocean with the underlying substrate), enabling conductivity estimations at shallower depths. Here we present the results of determining a 1-D conductivity-depth profile of oceanic lithosphere and upper mantle using...

  6. MAGNET

    by B. Curé

    2011-01-01

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

  7. Correlation between electrical conductivity and apparent diffusion coefficient in breast cancer: effect of necrosis on magnetic resonance imaging.

    Kim, Soo-Yeon; Shin, Jaewook; Kim, Dong-Hyun; Kim, Eun-Kyung; Moon, Hee Jung; Yoon, Jung Hyun; You, Jai Kyung; Kim, Min Jung

    2018-03-06

    To investigate the correlation between conductivity and ADC in invasive ductal carcinoma according to the presence of necrosis on MRI. Eighty-one women with invasive ductal carcinoma ≥1 cm on T2-weighted fast spin echo sequence of preoperative MRI were included. Phase-based MR electric properties tomography was used to reconstruct conductivity. Mean ADC was measured. Necrosis was defined as an area with very high T2 signal intensity. The relationship between conductivity and ADC was examined using Spearman's correlation coefficient (r). Multiple linear regression analysis was performed to identify factors associated with conductivity or ADC. In the total group, conductivity showed negative correlation with ADC (r = -0.357, p = 0.001). This correlation was maintained in the subgroup without necrosis (n = 53, r = -0.455, p = 0.001), but not in the subgroup with necrosis (n = 28, r = -0.080, p = 0.687). The correlation between the two parameters was different according to necrosis (r = -0.455 vs -0.080, p = 0.047). HER2 enriched subtype was independently associated with conductivity (p = 0.029). Necrosis on MRI was independently associated with ADC (p = 0.027). Conductivity shows negative correlation with ADC that is abolished by the presence of necrosis on MRI. • Electric conductivity showed negative correlation with ADC • However, the correlation was abolished by the presence of necrosis on MRI • HER2-enriched subtype was independently associated with conductivity • Necrosis on MRI was independently associated with ADC.

  8. Forensic Chemistry

    Bell, Suzanne

    2009-07-01

    Forensic chemistry is unique among chemical sciences in that its research, practice, and presentation must meet the needs of both the scientific and the legal communities. As such, forensic chemistry research is applied and derivative by nature and design, and it emphasizes metrology (the science of measurement) and validation. Forensic chemistry has moved away from its analytical roots and is incorporating a broader spectrum of chemical sciences. Existing forensic practices are being revisited as the purview of forensic chemistry extends outward from drug analysis and toxicology into such diverse areas as combustion chemistry, materials science, and pattern evidence.

  9. Defect chemistry modelling of oxygen-stoichiometry, vacancy concentrations, and conductivity of (La1-xSrx)(y)MnO3 +/-delta

    Poulsen, F.W.

    2000-01-01

    model, based on delocalised electrons, electron holes and all B-ions being trivalent is given in Appendix A. The sequential mathematical method allows us to calculate the high temperature oxygen partial pressure dependent properties of (La1-xSrx)(y)MnO3+/-delta in a unified manner irrespective...... are calculated by the small polaron model containing only ionic species - the B-ion may be Mn-B' (Mn2+), Mn-B(x) (Mn3+), and Mn-B(Mn4+). The A/B-ratio = y greatly influences the oxygen stoichiometry, oxygen ion vacancy- and cation vacancy concentrations and the total conductivity. Calculations are given...

  10. Numerical simulation of quench protection for a 1.5 T persistent mode MgB2 conduction-cooled MRI magnet

    Deissler, Robert J.; Baig, Tanvir; Poole, Charles; Amin, Abdullah; Doll, David; Tomsic, Michael; Martens, Michael

    2017-02-01

    The active quench protection of a 1.5 T MgB2 conduction-cooled MRI magnet operating in persistent current mode is considered. An active quench protection system relies on the detection of the resistive voltage developed in the magnet, which is used to trigger the external energizing of quench heaters located on the surfaces of all ten coil bundles. A numerical integration of the heat equation is used to determine the development of the temperature profile and the maximum temperature in the coil at the origin, or ‘hot spot’, of the quench. Both n-value of the superconductor and magnetoresistance of the wire are included in the simulations. An MgB2 wire manufactured by Hyper Tech Research, Inc. was used as the basis to model the wire for the simulations. With the proposed active quench protection system, the maximum temperature was limited to 200 K or less, which is considered low enough to prevent damage to the magnet. By substituting Glidcop for the Monel in the wire sheath or by increasing the thermal conductivity of the insulation, the margin for safe operation was further increased, the maximum temperature decreasing by more than 40 K. The strain on the MgB2 filaments is calculated using ANSYS, verifying that the stress and strain limits in the MgB2 superconductor and epoxy insulation are not exceeded.

  11. Coupled-analysis of current transport performance and thermal behaviour of conduction-cooled Bi-2223/Ag double-pancake coil for magnetic sail spacecraft

    Nagasaki, Y., E-mail: nagasaki@rish.kyoto-u.ac.jp [Research Institute of Sustainable Humanosphere, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Nakamura, T. [Graduate School of Engineering, Kyoto University, Kyotodaigakukatsura, Nishikyo, Kyoto 615-8530 (Japan); Funaki, I. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 252-5210 (Japan); Ashida, Y.; Yamakawa, H. [Research Institute of Sustainable Humanosphere, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

    2013-09-15

    Highlights: • We model current transport and thermal performances of conduction-cooled HTS coil. • We investigate the effect of the longitudinal inhomogeneity of the HTS tape. • The analysis can precisely estimate performances of the conduction-cooled coil. • The longitudinal inhomogeneity of the HTS tape deteriorates coil performances. • Quench currents of the HTS coil are not consistent with the critical currents. -- Abstract: This paper investigated the quantitative current transport performance and thermal behaviour of a high temperature superconducting (HTS) coil, and the effect of the critical current inhomogeneity along the longitudinal direction of HTS tapes on the coil performances. We fabricated a double-pancake coil using a Bi-2223/Ag tape with a length of 200 m as a scale-down model for a magnetic sail spacecraft. We measured the current transport property and temperature rises during current applications of the HTS coil in a conduction-cooled system, and analytically reproduced the results on the basis of the percolation depinning model and three-dimensional heat balance equation. The percolation depinning model can describe the electric field versus current density of HTS tapes as a function of temperature and magnetic field vector, and we also introduced the longitudinal distribution of the local critical current of the HTS tape into this model. As a result, we can estimate the critical currents of the HTS coil within 10% error for a wide range of the operational temperatures from 45 to 80 K, and temperature rises on the coil during current applications. These results showed that our analysis and conduction-cooled system were successfully realized. The analysis also suggested that the critical current inhomogeneity along the length of the HTS tape deteriorated the current transport performance and thermal stability of the HTS coil. The present study contributes to the characterization of HTS coils and design of a coil system for the

  12. Coupled-analysis of current transport performance and thermal behaviour of conduction-cooled Bi-2223/Ag double-pancake coil for magnetic sail spacecraft

    Nagasaki, Y.; Nakamura, T.; Funaki, I.; Ashida, Y.; Yamakawa, H.

    2013-01-01

    Highlights: • We model current transport and thermal performances of conduction-cooled HTS coil. • We investigate the effect of the longitudinal inhomogeneity of the HTS tape. • The analysis can precisely estimate performances of the conduction-cooled coil. • The longitudinal inhomogeneity of the HTS tape deteriorates coil performances. • Quench currents of the HTS coil are not consistent with the critical currents. -- Abstract: This paper investigated the quantitative current transport performance and thermal behaviour of a high temperature superconducting (HTS) coil, and the effect of the critical current inhomogeneity along the longitudinal direction of HTS tapes on the coil performances. We fabricated a double-pancake coil using a Bi-2223/Ag tape with a length of 200 m as a scale-down model for a magnetic sail spacecraft. We measured the current transport property and temperature rises during current applications of the HTS coil in a conduction-cooled system, and analytically reproduced the results on the basis of the percolation depinning model and three-dimensional heat balance equation. The percolation depinning model can describe the electric field versus current density of HTS tapes as a function of temperature and magnetic field vector, and we also introduced the longitudinal distribution of the local critical current of the HTS tape into this model. As a result, we can estimate the critical currents of the HTS coil within 10% error for a wide range of the operational temperatures from 45 to 80 K, and temperature rises on the coil during current applications. These results showed that our analysis and conduction-cooled system were successfully realized. The analysis also suggested that the critical current inhomogeneity along the length of the HTS tape deteriorated the current transport performance and thermal stability of the HTS coil. The present study contributes to the characterization of HTS coils and design of a coil system for the

  13. Systems chemistry: All in a spin

    Clark, Lucy; Lightfoot, Philip

    2016-05-01

    A fundamental challenge in systems chemistry is to engineer the emergence of complex behaviour. The collective structures of metal cyanide chains have now been interpreted in the same manner as the myriad of magnetic phases displayed by frustrated spin systems, highlighting a symbiotic approach between systems chemistry and magnetism.

  14. MAGNET

    Benoit Curé

    2010-01-01

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

  15. MAGNET

    B. Curé

    2012-01-01

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

  16. MAGNET

    B. Curé

    2012-01-01

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

  17. Numerical Study of Thermo-Fluid Features of Electrically Conducting Fluids in Tube Bank Heat Exchangers Exposed to Uniform Magnetic Fields

    Oh, Jin Ho; Kang, Namcheol [Kyungpook Nat’l Univ., Daegu (Korea, Republic of)

    2017-10-15

    When an electrically conducting fluid flows through a staggered tube bank, the heat transfer and fluid flow features are changed by the externally introduced magnetic field. This study provides a numerical investigation of this phenomenon. Heat and fluid flows are investigated for unsteady laminar flows at Reynolds numbers of 50 and 100 with the Hartmann number gradually increasing from zero to 100. As the Hartmann number increases, and owing to the effects of the introduced magnetic field, the velocity boundary layer near the tube wall is thinned, the flow separation is delayed downstream, and the shrinkage of a recirculation zone formed near the rear side is observed. Based on these thermo-fluid deformations, the resulting changes in the local and average Nusselt number are investigated.

  18. Effect of oxygen clusters on optics, magnetism, and conductivity of (In2O3)0.9(SrO)0.1

    Okunev, V. D.; Szymczak, H.; Szymczak, R.; Gierłowski, P.; Glot, A. B.; Bondarchuk, A. N.; Burkhovetski, V. V.

    2016-04-01

    We show that in In2O3-SrO ceramics with disordered structure and oxygen clusters in nanovoids, the band tails of valence and conduction bands form "negative" gap. Two types of magnetism are observed. One of them caused by formation of the "dangling bond+O2- ion" centers has been found in the samples saturated with oxygen. Another type is associated with the presence of dangling bonds in the oxygen-depleted samples. At Tconductivity of the samples. At T<54.8 K, the effects related to magnetic phase transitions in the clusters of crystalline oxygen are observed. The changes in resistance of the samples in the range of T=5-300 K correspond to the Mott's law at a dependence of local activation energy on the phase state of oxygen clusters.

  19. High temperature water chemistry monitoring

    Aaltonen, P.

    1992-01-01

    Almost all corrosion phenomena in nuclear power plants can be prevented or at least damped by water chemistry control or by the change of water chemistry control or by the change of water chemistry. Successful water chemistry control needs regular and continuous monitoring of such water chemistry parameters like dissolved oxygen content, pH, conductivity and impurity contents. Conventionally the monitoring is carried out at low pressures and temperatures, which method, however, has some shortcomings. Recently electrodes have been developed which enables the direct monitoring at operating pressures and temperatures. (author). 2 refs, 5 figs

  20. Magnetic resonance visualization of conductive structures by sequence-triggered direct currents and spin-echo phase imaging

    Eibofner, Frank; Wojtczyk, Hanne; Graf, Hansjörg, E-mail: hansjoerg.graf@med.uni-tuebingen.de, E-mail: drGraf@t-online.de [Section on Experimental Radiology, University Hospital Tübingen, Tübingen D-72076 (Germany); Clasen, Stephan [Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen D-72076 (Germany)

    2014-06-15

    Purpose: Instrument visualization in interventional magnetic resonance imaging (MRI) is commonly performed via susceptibility artifacts. Unfortunately, this approach suffers from limited conspicuity in inhomogeneous tissue and disturbed spatial encoding. Also, susceptibility artifacts are controllable only by sequence parameters. This work presents the basics of a new visualization method overcoming such problems by applying sequence-triggered direct current (DC) pulses in spin-echo (SE) imaging. SE phase images allow for background free current path localization. Methods: Application of a sequence-triggered DC pulse in SE imaging, e.g., during a time period between radiofrequency excitation and refocusing, results in transient field inhomogeneities. Dependent on the additional z-magnetic field from the DC, a phase offset results despite the refocusing pulse. False spatial encoding is avoided by DC application during periods when read-out or slice-encoding gradients are inactive. A water phantom containing a brass conductor (water equivalent susceptibility) and a titanium needle (serving as susceptibility source) was used to demonstrate the feasibility. Artifact dependence on current strength and orientation was examined. Results: Without DC, the brass conductor was only visible due to its water displacement. The titanium needle showed typical susceptibility artifacts. Applying triggered DC pulses, the phase offset of spins near the conductor appeared. Because SE phase images are homogenous also in regions of persistent field inhomogeneities, the position of the conductor could be determined with high reliability. Artifact characteristic could be easily controlled by amperage leaving sequence parameters unchanged. For an angle of 30° between current and static field visualization was still possible. Conclusions: SE phase images display the position of a conductor carrying pulsed DC free from artifacts caused by persistent field inhomogeneities. Magnitude and phase

  1. Central Motor Conduction Studies and Diagnostic Magnetic Resonance Imaging in Children with Severe Primary and Secondary Dystonia

    McClelland, Verity; Mills, Kerry; Siddiqui, Ata; Selway, Richard; Lin, Jean-Pierre

    2011-01-01

    Aim: Dystonia in childhood has many causes. Imaging may suggest corticospinal tract dysfunction with or without coexistent basal ganglia damage. There are very few published neurophysiological studies on children with dystonia; one previous study has focused on primary dystonia. We investigated central motor conduction in 62 children (34 males, 28…

  2. Structural and Magnetic Diversity in Alkali-Metal Manganate Chemistry: Evaluating Donor and Alkali-Metal Effects in Co-complexation Processes.

    Uzelac, Marina; Borilovic, Ivana; Amores, Marco; Cadenbach, Thomas; Kennedy, Alan R; Aromí, Guillem; Hevia, Eva

    2016-03-24

    By exploring co-complexation reactions between the manganese alkyl Mn(CH2SiMe3)2 and the heavier alkali-metal alkyls M(CH2SiMe3) (M=Na, K) in a benzene/hexane solvent mixture and in some cases adding Lewis donors (bidentate TMEDA, 1,4-dioxane, and 1,4-diazabicyclo[2,2,2] octane (DABCO)) has produced a new family of alkali-metal tris(alkyl) manganates. The influences that the alkali metal and the donor solvent impose on the structures and magnetic properties of these ates have been assessed by a combination of X-ray, SQUID magnetization measurements, and EPR spectroscopy. These studies uncover a diverse structural chemistry ranging from discrete monomers [(TMEDA)2 MMn(CH2SiMe3)3] (M=Na, 3; M=K, 4) to dimers [{KMn(CH2SiMe3)3 ⋅C6 H6}2] (2) and [{NaMn(CH2SiMe3)3}2 (dioxane)7] (5); and to more complex supramolecular networks [{NaMn(CH2SiMe3)3}∞] (1) and [{Na2Mn2 (CH2SiMe3)6 (DABCO)2}∞] (7)). Interestingly, the identity of the alkali metal exerts a significant effect in the reactions of 1 and 2 with 1,4-dioxane, as 1 produces coordination adduct 5, while 2 forms heteroleptic [{(dioxane)6K2Mn2 (CH2SiMe3)4(O(CH2)2OCH=CH2)2}∞] (6) containing two alkoxide-vinyl anions resulting from α-metalation and ring opening of dioxane. Compounds 6 and 7, containing two spin carriers, exhibit antiferromagnetic coupling of their S=5/2 moments with varying intensity depending on the nature of the exchange pathways. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. An FDTD Study of Errors in Magnetic Direction Finding of Lightning Due to the Presence of Conducting Structure Near the Field Measuring Station

    Yosuke Suzuki

    2016-07-01

    Full Text Available Lightning electromagnetic fields in the presence of conducting (grounded structure having a height of 60 m and a square cross-section of 40 m × 40 m within about 100 m of the observation point are analyzed using the 3D finite-difference time-domain (FDTD method. Influence of the conducting structure on the two orthogonal components of magnetic field is analyzed, and resultant errors in the estimated lightning azimuth are evaluated. Influences of ground conductivity and lightning current waveshape parameters are also examined. When the azimuth vector passes through the center of conducting structure diagonally (e.g., azimuth angle is 45° or parallel to its walls (e.g., azimuth angle is 0°, the presence of conducting structure equally influences Hx and Hy, so that Hx/Hy is the same as in the absence of structure. Therefore, no azimuth error occurs in those configurations. When the conducting structure is not located on the azimuth vector, the structure influences Hx and Hy differently, with the resultant direction finding error being greater when the structure is located closer to the observation point.

  4. MAGNET

    B. Curé

    2012-01-01

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

  5. MAGNET

    B. Curé

    2013-01-01

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

  6. MAGNET

    Benoit Curé

    2010-01-01

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

  7. MAGNET

    B. Curé

    2011-01-01

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

  8. Optimum Depth of Investigation and Conductivity Response Rejection of the Different Electromagnetic Devices Measuring Apparent Magnetic Susceptibility

    Benech , Christophe; Marmet , Eric

    1999-01-01

    International audience; Electromagnetic susceptibility surveys are valuable for archaeological prospection owing to their ability to cover large areas of land. Their use, however, is often compromised by the conductivity influence of the soil and the limited investigation depth of the susceptibility response. To examine these constraints further, we compared the characteristics of two types of apparatus: coincident loop (e.g. Bartington MS2 field coil) and 'Slingram' instruments (EM38, SH3, C...

  9. Organic chemistry

    2003-08-01

    This book with sixteen chapter explains organic chemistry on linkage isomerism such as alkane, cycloalkane, alkene, aromatic compounds, stereo selective isomerization, aromatic compounds, stereo selective isomerization, organic compounds, stereo selective isomerization, organic halogen compound, alcohol, ether, aldehyde and ketone, carboxylic acid, dicarboxylic acid, fat and detergent, amino, carbohydrate, amino acid and protein, nucleotide and nucleic acid and spectroscopy, a polymer and medical chemistry. Each chapter has introduction structure and characteristic and using of organic chemistry.

  10. Radiation chemistry

    None

    1973-07-01

    Research progress is reported on radiation chemistry of heavy elements that includes the following topics: radiation chemistry of plutonium in nitric acid solutions (spectrophotometric analysis and gamma radiolysis of Pu(IV) and Pu(VI) in nitric acid solution); EPR studies of intermediates formed in radiolytic reactions with aqueous medium; two-phase radiolysis and its effect on the distribution coefficient of plutonium; and radiation chemistry of nitric acid. (DHM)

  11. Technetium chemistry

    Burns, C.; Bryan, J.; Cotton, F.; Ott, K.; Kubas, G.; Haefner, S.; Barrera, J.; Hall, K.; Burrell, A.

    1996-01-01

    Technetium chemistry is a young and developing field. Despite the limited knowledge of its chemistry, technetium is the workhorse for nuclear medicine. Technetium is also a significant environmental concern because it is formed as a byproduct of nuclear weapons production and fission-power generators. Development of new technetium radio-pharmaceuticals and effective environmental control depends strongly upon knowledge of basic technetium chemistry. The authors performed research into the basic coordination and organometallic chemistry of technetium and used this knowledge to address nuclear medicine and environmental applications. This is the final report of a three-year Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL)

  12. Chemistry Technology

    Federal Laboratory Consortium — Chemistry technology experts at NCATS engage in a variety of innovative translational research activities, including:Design of bioactive small molecules.Development...

  13. Heat Capacity and Thermal Conductance Measurements of a Superconducting-Normal Mixed State by Detection of Single 3 eV Photons in a Magnetic Penetration Thermometer

    Stevenson, T. R.; Balvin, M. A.; Bandler, S. R.; Denis, K. L.; Lee, S.-J.; Nagler, P. C.; Smith, S. J.

    2015-01-01

    We report on measurements of the detected signal pulses in a molybdenum-gold Magnetic Penetration Thermometer (MPT) in response to absorption of one or more 3 eV photons. We designed and used this MPT sensor for x-ray microcalorimetry. In this device, the diamagnetic response of a superconducting MoAu bilayer is used to sense temperature changes in response to absorbed photons, and responsivity is enhanced by a Meissner transition in which the magnetic flux penetrating the sensor changes rapidly to minimize free energy in a mixed superconducting normal state. We have previously reported on use of our MPT to study a thermal phonon energy loss to the substrate when absorbing x-rays. We now describe results of extracting heat capacity C and thermal conductance G values from pulse height and decay time of MPT pulses generated by 3 eV photons. The variation in C and G at temperatures near the Meissner transition temperature (set by an internal magnetic bias field) allow us to probe the behavior in superconducting normal mixed state of the condensation energy and the electron cooling power resulting from quasi-particle recombination and phonon emission. The information gained on electron cooling power is also relevant to the operation of other superconducting detectors, such as Microwave Kinetic Inductance Detectors.

  14. MAGNET

    B. Curé

    2011-01-01

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

  15. Effects of (La, Sr) co-doping on electrical conduction and magnetic properties of BiFeO3 nanoparticles

    Liu Li; Wang Shouyu; Yin Zi; Zhang Chuang; Li Xiu; Yang Jiabin; Liu Weifang; Xu Xunling

    2016-01-01

    Multiferroic material as a photovoltaic material has gained considerable attention in recent years. Nanoparticles (NPs) La 0.1 Bi 0.9−x Sr x FeO y (LBSF, x = 0, 0.2, 0.4) with dopant Sr 2+ ions were synthesized by the sol–gel method. A systematic change in the crystal structure from rhombohedral to tetragonal upon increasing Sr doping was observed. There is an obvious change in the particle size from 180 nm to 50 nm with increasing Sr substitution into LBFO. It was found that Sr doping effectively narrows the band gap from ∼ 2.08 eV to ∼ 1.94 eV, while it leads to an apparent enhancement in the electrical conductivity of LBSF NPs, making a transition from insulator to semiconductor. This suggests an effective way to modulate the conductivity of BiFeO 3 -based multiferroic materials with pure phase by co-doping with La and Sr at the A sites of BiFeO 3 . (paper)

  16. Magnetic quantum oscillations of diagonal conductivity in a two-dimensional conductor with a weak square superlattice modulation under conditions of the integer quantum Hall effect

    Gvozdikov, V M; Taut, M

    2009-01-01

    We report on analytical and numerical studies of the magnetic quantum oscillations of the diagonal conductivity σ xx in a two-dimensional conductor with a weak square superlattice modulation under conditions of the integer quantum Hall (IQHE) effect. The quantum Hall effect in such a system differs from the conventional IQHE, in which the finite width of the Landau bands is due to disorder only. The superlattice modulation potential yields a fractal splitting of the Landau levels into Hofstadter minibands. For rational flux through a unit cell, the minibands have a finite width and intrinsic dispersion relations. We consider a regime, now accessible experimentally, in which disorder does not wash out the fractal internal gap structure of the Landau bands completely. We found the following distinctions from the conventional IQHE produced by the superlattice: (i) the peaks in diagonal conductivity are split due to the Hofstadter miniband structure of Landau bands; (ii) the number of split peaks in the bunch, their positions and heights depend irregularly on the magnetic field and the Fermi energy; (iii) the gaps between the split Landau bands (and related quantum Hall plateaus) become narrower with the superlattice modulation than without it.

  17. Current organic chemistry

    1997-01-01

    Provides in depth reviews on current progress in the fields of asymmetric synthesis, organometallic chemistry, bioorganic chemistry, heterocyclic chemistry, natural product chemistry, and analytical...

  18. Nuclear chemistry

    Vertes, A.; Kiss, I.

    1987-01-01

    This book is an introduction to the application of nuclear science in modern chemistry. The first group of chapters discuss the basic phenomena and concepts of nuclear physics with emphasis on their relation to chemical problems, including the main properties and the composition of atomic nuclei, nuclear reactions, radioactive decay and interactions of radiation with matter. These chapters provide the basis for understanding the following chapters which encompass the wide scope of nuclear chemistry. The methods of the investigation of chemical structure based on the interaction of nuclear radiation with matter including positronium chemistry and other exotic atoms is elaborated in particular detail. Separate chapters are devoted to the use of radioactive tracers, the chemical consequences of nuclear processes (i.e. hot atom chemistry), radiation chemistry, isotope effects and their applications, and the operation of nuclear reactors

  19. Nuclear chemistry

    Vertes, A.; Kiss, I.

    1987-01-01

    This book is an introduction to the application of nuclear science in modern chemistry. The first group of chapters discuss the basic phenomena and concepts of nuclear physics with emphasis on their relation to chemical problems, including the main properties and the composition of atomic nuclei, nuclear reactions, radioactive decay and interactions of radiation with matter. These chapters provide the basis for understanding the following chapters which encompass the wide scope of nuclear chemistry. The methods of the investigation of chemical structure based on the interaction of nuclear radiation with matter including positronium chemistry and other exotic atoms is elaborated in particular detail. Separate chapters are devoted to the use of radioactive tracers, the chemical consequences of nuclear processes (i.e. hot atom chemistry), radiation chemistry, isotope effects and their applications, and the operation of nuclear reactors. (Auth.)

  20. AC conductivity, magnetic and shielding effectiveness studies on polyaniline embedded Co0.5Mn0.5Fe2O4 nanoparticles for electromagnetic interference suppression

    Gurusiddesh, M.; Madhu, B. J.; Shankaramurthy, G. J.

    2018-05-01

    Electrically conducting Polyaniline (PANI)/Co0.5Mn0.5Fe2O4 nanocomposites are synthesized by in situ polymerization of aniline monomer in the presence of Co0.5Mn0.5Fe2O4 nanoparticles. Structural studies on the synthesized samples have been carried out using X-ray diffraction technique, Field emission scanning electron microscopy and Energy dispersive X-ray spectroscopy. Frequency dependent ac conductivity studies on the prepared samples revealed that conductivity of the composite is high compared to Co0.5Mn0.5Fe2O4 nanoparticles. Further, both the samples exhibited hysteresis behavior under the applied magnetic field. Electromagnetic interference (EMI) shielding effectiveness of both the samples decreases with increase in the applied frequency in the studied frequency range. Maximum shielding effectiveness (SE) of 31.49 dB and 62.84 dB were obtained for Co0.5Mn0.5Fe2O4 nanoparticles and PANI/Co0.5Mn0.5Fe2O4 nanocomposites respectively in the studied frequency range. Observed higher EMI shielding in the composites was attributed to its high electrical conductivity.

  1. Thermal conductivity and viscosity of hybrid nanfluids prepared with magnetic nanodiamond-cobalt oxide (ND-Co3O4 nanocomposite

    L. Syam Sundar

    2016-03-01

    Full Text Available Synthesis of magnetic nanodiamond-cobalt oxide (ND-Co3O4 nanocomposite material; preparation of nanofluids and estimation of thermal properties such as thermal conductivity and viscosity has been explained experimentally in this paper. The nanocomposite material has been synthesized by using in-situ growth technique and chemical coprecipitation between cobalt chloride and sodium borohydrate. The various techniques such as XRD, TEM, XPS and VSM have been used to confirm the ND and Co3O4 phase of synthesized nanocomposite. The hybrid nanofluids have been prepared by dispersing synthesized ND-Co3O4 nanocomposite in water, ethylene glycol/water mixtures. The thermal properties such as thermal conductivity and viscosity have been measured experimentally at different weight concentrations and temperatures. The results reveal that the thermal conductivity enhancements are about 16%, 9%, 14%, 11% and 10% for water, EG, 20:80%, 40:60%, and 60:40% EG/W based nanofluids at 0.15 wt% concentrations and at 60 °C respectively. Similarly the viscosity enhancements are about 1.45-times, 1.46-times, 1.15-times, 1.19-times, and 1.51-times for water, EG, 20:80%, 40:60%, and 60:40% EG/W based nanofluids at 0.15 wt% concentrations and at 60 °C respectively. Based on the experimental data new correlations for thermal conductivity and viscosity have been developed.

  2. MAGNET

    Benoit Curé

    2010-01-01

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

  3. MAGNET

    B. Curé

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

  4. MAGNET

    Benoit Curé.

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

  5. MAGNET

    B. Curé

    2013-01-01

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

  6. Quantum chemistry

    Lowe, John P

    1993-01-01

    Praised for its appealing writing style and clear pedagogy, Lowe's Quantum Chemistry is now available in its Second Edition as a text for senior undergraduate- and graduate-level chemistry students. The book assumes little mathematical or physical sophistication and emphasizes an understanding of the techniques and results of quantum chemistry, thus enabling students to comprehend much of the current chemical literature in which quantum chemical methods or concepts are used as tools. The book begins with a six-chapter introduction of standard one-dimensional systems, the hydrogen atom,

  7. Conducting polymer hydrogels

    Stejskal, Jaroslav

    2017-01-01

    Roč. 71, č. 2 (2017), s. 269-291 ISSN 0366-6352 R&D Projects: GA ČR(CZ) GA16-02787S Institutional support: RVO:61389013 Keywords : aerogel * conducting polymers * conductivity Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 1.258, year: 2016

  8. Defect formation in LaGa(Mg,Ni)O3-δ : A statistical thermodynamic analysis validated by mixed conductivity and magnetic susceptibility measurements

    Naumovich, E. N.; Kharton, V. V.; Yaremchenko, A. A.; Patrakeev, M. V.; Kellerman, D. G.; Logvinovich, D. I.; Kozhevnikov, V. L.

    2006-08-01

    A statistical thermodynamic approach to analyze defect thermodynamics in strongly nonideal solid solutions was proposed and validated by a case study focused on the oxygen intercalation processes in mixed-conducting LaGa0.65Mg0.15Ni0.20O3-δ perovskite. The oxygen nonstoichiometry of Ni-doped lanthanum gallate, measured by coulometric titration and thermogravimetric analysis at 923-1223K in the oxygen partial pressure range 5×10-5to0.9atm , indicates the coexistence of Ni2+ , Ni3+ , and Ni4+ oxidation states. The formation of tetravalent nickel was also confirmed by the magnetic susceptibility data at 77-600K , and by the analysis of p -type electronic conductivity and Seebeck coefficient as function of the oxygen pressure at 1023-1223K . The oxygen thermodynamics and the partial ionic and hole conductivities are strongly affected by the point-defect interactions, primarily the Coulombic repulsion between oxygen vacancies and/or electron holes and the vacancy association with Mg2+ cations. These factors can be analyzed by introducing the defect interaction energy in the concentration-dependent part of defect chemical potentials expressed by the discrete Fermi-Dirac distribution, and taking into account the probabilities of local configurations calculated via binomial distributions.

  9. Two-phase mixture model simulation of the hydro-thermal behavior of an electrical conductive ferrofluid in the presence of magnetic fields

    Aminfar, H.; Mohammadpourfard, M.; Mohseni, F.

    2012-01-01

    This paper presents a numerical investigation of the hydro-thermal behavior of a ferrofluid (sea water and 4 vol% Fe 3 O 4 ) in a rectangular vertical duct in the presence of different magnetic fields, using two-phase mixture model and control volume technique. Considering the electrical conductivity of the ferrofluid, in addition to the ferrohydrodynamics principles, the magnetohydrodynamics principles have also been taken into account. Three cases for magnetic field have been considered to study mixed convection of the ferrofluid: non-uniform axial field (negative and positive gradient), uniform transverse field and another case when both fields are applied simultaneously. The results indicate that negative gradient axial field and uniform transverse field act similarly and enhance both the Nusselt number and the friction factor, while positive gradient axial field decreases them. It is also concluded that, under the influence of both fields by increasing the intensity of uniform transverse field the effect of non-uniform axial fields decrease. - Highlights: ► In addition to the FHD principles the MHD principles have also been taken into account. ► The mixed convective hydrodynamic and heat transfer have been investigated. ► Negative gradient axial and uniform transverse field enhance Nusselt number and friction factor. ► Positive gradient axial field decreases Nusselt number and friction factor. ► Increase in intensity of transverse fields decreases the effects of non-uniform axial fields.

  10. MAGNET

    Benoit Curé

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

  11. MAGNET

    B. Curé

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

  12. Materials Chemistry

    Fahlman, Bradley D

    2011-01-01

    The 2nd edition of Materials Chemistry builds on the strengths that were recognized by a 2008 Textbook Excellence Award from the Text and Academic Authors Association (TAA). Materials Chemistry addresses inorganic-, organic-, and nano-based materials from a structure vs. property treatment, providing a suitable breadth and depth coverage of the rapidly evolving materials field. The 2nd edition continues to offer innovative coverage and practical perspective throughout. After briefly defining materials chemistry and its history, seven chapters discuss solid-state chemistry, metals, semiconducting materials, organic "soft" materials, nanomaterials, and materials characterization. All chapters have been thoroughly updated and expanded with, for example, new sections on ‘soft lithographic’ patterning, ‘click chemistry’ polymerization, nanotoxicity, graphene, as well as many biomaterials applications. The polymer and ‘soft’ materials chapter represents the largest expansion for the 2nd edition. Each ch...

  13. Analytical chemistry

    Choi, Jae Seong

    1993-02-15

    This book is comprised of nineteen chapters, which describes introduction of analytical chemistry, experimental error and statistics, chemistry equilibrium and solubility, gravimetric analysis with mechanism of precipitation, range and calculation of the result, volume analysis on general principle, sedimentation method on types and titration curve, acid base balance, acid base titration curve, complex and firing reaction, introduction of chemical electro analysis, acid-base titration curve, electrode and potentiometry, electrolysis and conductometry, voltammetry and polarographic spectrophotometry, atomic spectrometry, solvent extraction, chromatograph and experiments.

  14. Analytical chemistry

    Choi, Jae Seong

    1993-02-01

    This book is comprised of nineteen chapters, which describes introduction of analytical chemistry, experimental error and statistics, chemistry equilibrium and solubility, gravimetric analysis with mechanism of precipitation, range and calculation of the result, volume analysis on general principle, sedimentation method on types and titration curve, acid base balance, acid base titration curve, complex and firing reaction, introduction of chemical electro analysis, acid-base titration curve, electrode and potentiometry, electrolysis and conductometry, voltammetry and polarographic spectrophotometry, atomic spectrometry, solvent extraction, chromatograph and experiments.

  15. Analytical chemistry

    Chae, Myeong Hu; Lee, Hu Jun; Kim, Ha Seok

    1989-02-15

    This book give explanations on analytical chemistry with ten chapters, which deal with development of analytical chemistry, the theory of error with definition and classification, sample and treatment gravimetry on general process of gravimetry in aqueous solution and non-aqueous solution, precipitation titration about precipitation reaction and types, complexometry with summary and complex compound, oxidation-reduction equilibrium on electrode potential and potentiometric titration, solvent extraction and chromatograph and experiment with basic operation for chemical experiment.

  16. Analytical chemistry

    Chae, Myeong Hu; Lee, Hu Jun; Kim, Ha Seok

    1989-02-01

    This book give explanations on analytical chemistry with ten chapters, which deal with development of analytical chemistry, the theory of error with definition and classification, sample and treatment gravimetry on general process of gravimetry in aqueous solution and non-aqueous solution, precipitation titration about precipitation reaction and types, complexometry with summary and complex compound, oxidation-reduction equilibrium on electrode potential and potentiometric titration, solvent extraction and chromatograph and experiment with basic operation for chemical experiment.

  17. Green Chemistry

    Collison, Melanie

    2011-05-15

    Green chemistry is the science of chemistry used in a way that will not use or create hazardous substances. Dr. Rui Resendes is working in this field at GreenCentre Canada, an offshoot of PARTEQ Innovations in Kingston, Ontario. GreenCentre's preliminary findings suggest their licensed product {sup S}witchable Solutions{sup ,} featuring 3 classes of solvents and a surfactant, may be useful in bitumen oil sands extraction.

  18. Plutonium oxychalcogenides Pu2O2X (X=O, S, Se, Te) crystal chemistry, magnetic and electrical properties. 5f electrons delocalization

    Costantini, Jean-Marc.

    1980-05-01

    We have studied the influence of the chalcogen X on the bonding and on the magnetic and electrical properties of the oxychalcogenides Pu 2 O 2 X. These compounds are isostructural with hexagonal La 2 O 3 for X=O, S, Se and with tetragonal La 2 O 2 Te for X=Te. Comparison of Nd 2 O 2 X and Pu 2 O 2 X cell volumes showed that plutonium crystal radius decreases from Pu 2 O 3 through Pu 2 O 2 Te with increasing 5f electrons delocalization and 5f-np overlap. Superexchange interactions through O 2- and X 2- were thought to be responsible for the observed antiferromagnetic ordering. Neel temperatures increase from Pu 2 O 3 through Pu 2 O 2 Te showing that these interactions and subsequent 5f-np covalency are strengthened as chalcogen electronegativity decreases. Hexagonal Pu 2 O 3 is an insulator while the other compounds are semi-conductors with energy gaps around 0.6 eV which were interpreted as the separation between the 6d-7s conduction band and the np valence band. The localized 5f states were located just below the np band, partially overlapping it [fr

  19. Report on achievements in fiscal 1999. Research and development of electric power storage using high-temperature super-conductive flywheels (research and development on manufacture of super-conductive magnetic bearings); 1999 nendo koon chodendo flywheel denryoku chozo kenkyu kaihatsu. Chodendo jiki jikuuke no seisaku no kenkyu kaihatsu

    NONE

    2000-05-01

    Introduction of electric power storage equipment is sought, which will be discretely installed in power distribution substations. Therefore, elementary technologies were researched on 'manufacture of super-conductive magnetic bearings' intended for practical application of an electric power storage system of 10-MWh class using high-temperature super-conductive flywheels. Research and development has been performed on different kinds of super-conductive magnetic bearings which combine high-temperature super-conductive materials with permanent magnets. In order to measure the characteristics of the super-conductive magnetic bearings, measurements were executed on rotation loss, loading power and bearing constants. In the measurement of the rotation loss, a {phi} 180 axial type super-conductive magnetic bearing using an Sm-based superconductor ({phi} 180AxSMB2) was given various kinds of tests by using a rotation loss measuring and testing machine. The results were compared with those for the {phi} 180AxSMB1 using the YBCO-based superconductor and other SMBs. In the measurements for the other items, various items were measured on dynamic rotation properties of the {phi} 180AxSMB and {phi} 180RaSMB by using a static bearing constant testing machine. In discussing the loading power characteristics, the dynamic rotation properties of the {phi} 180RaSMB were measured, and the loading power characteristics were discussed on super-conductive magnetic bearings for medium size models and super-conductive magnetic bearings for large system FS. (NEDO)

  20. Optimization of multiple coils immersed in a conducting liquid for half-hemisphere or whole-brain deep transcranial magnetic stimulation: a simulation study.

    Sousa, Sónia C P; Almeida, Jorge; Cavaleiro Miranda, Pedro; Salvador, Ricardo; Silvestre, João; Simões, Hugo; Crespo, Paulo

    2014-01-01

    Transcranial magnetic stimulation (TMS) was proposed in 1985. Nevertheless, its wider use in the treatment of several neurologic diseases has been hindered by its inability to stimulate deep-brain regions. This is mainly due to the physical limiting effect arising from the presence of surface discontinuities, particularly between the scalp and air. Here, we present the optimization of a system of large multiple coils for whole-brain and half-hemisphere deep TMS, termed orthogonal configuration. COMSOL(®)-based simulations show that the system is capable of reaching the very center of a spherical brain phantom with 58% induction relative to surface maximum. Such penetration capability surpasses to the best of our knowledge that of existing state of the art TMS systems. This induction capability strongly relies on the immersion of the stimulating coils and part of the head of the patient in a conducting liquid (e.g. simple saline solution). We show the impact of the presence of this surrounding conducting liquid by comparing the performance of our system with and without such liquid. In addition, we also compare the performance of the proposed coil with that of a circular coil, a figure-eight coil, and the H-coil. Finally, in addition to its whole-brain stimulation capability (e.g. potentially useful for prophylaxis of epileptic patients) the system is also able to stimulate mainly one brain hemisphere, which may be useful in stroke rehabilitation, among other applications.

  1. Dye-Sensitized Molecular Charge Transfer Complexes: Magnetic and Conduction Properties in the Photoexcited States of Ni(dmit2 Salts Containing Photosensitive Dyes

    Ryoma Yamamoto

    2017-05-01

    Full Text Available Photosensitive dyes often induce charge transfer (CT between adjacent chemical species and themselves under irradiation of appropriate wavelengths. Because of the reversibility and selectivity of such CT, it is considered to be interesting to utilize such dyes as optically controllable trigger components for conduction and magnetism in the photoexcited states of organic materials. Based on this idea, such a type of new salts, i.e., γ- and δ-DiCC[Ni(dmit2] in addition to DiCC2[Ni(dmit2]3 have been prepared, characterized and their physical and structural properties have been examined both under dark and irradiated conditions (dmit2− = 1,3-dithiole-2-thione-4,5-dithiolate, DiCC+ = 3,3′-Dihexyloxacarbocyanine monocation. Among them, under UV (254–450 nm irradiation, δ-DiCC[Ni(dmit2] exhibited photoconductivity being six times as high as its dark conductivity at room temperature. The electron spin resonance (ESR spectra have demonstrated that there are photoexcited spins on both DiCC and [Ni(dmit2] species as a result of the CT transition between them, serving as localized spins (DiCC and carriers ([Ni(dmit2], respectively. The results obtained in this work have indicated that the strategy mentioned above is effective in developing organic photoresponsive semiconductors with paramagnetism.

  2. Magnetic

    Aboud, Essam; El-Masry, Nabil; Qaddah, Atef; Alqahtani, Faisal; Moufti, Mohammed R. H.

    2015-06-01

    The Rahat volcanic field represents one of the widely distributed Cenozoic volcanic fields across the western regions of the Arabian Peninsula. Its human significance stems from the fact that its northern fringes, where the historical eruption of 1256 A.D. took place, are very close to the holy city of Al-Madinah Al-Monawarah. In the present work, we analyzed aeromagnetic data from the northern part of Rahat volcanic field as well as carried out a ground gravity survey. A joint interpretation and inversion of gravity and magnetic data were used to estimate the thickness of the lava flows, delineate the subsurface structures of the study area, and estimate the depth to basement using various geophysical methods, such as Tilt Derivative, Euler Deconvolution and 2D modeling inversion. Results indicated that the thickness of the lava flows in the study area ranges between 100 m (above Sea Level) at the eastern and western boundaries of Rahat Volcanic field and getting deeper at the middle as 300-500 m. It also showed that, major structural trend is in the NW direction (Red Sea trend) with some minor trends in EW direction.

  3. MAGNET

    Benoit Curé

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

  4. MAGNET

    B. Curé

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

  5. MAGNET

    Benoit Curé

    2013-01-01

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

  6. General chemistry

    Kwon, Yeong Sik; Lee, Dong Seop; Ryu, Haung Ryong; Jang, Cheol Hyeon; Choi, Bong Jong; Choi, Sang Won

    1993-07-01

    The book concentrates on the latest general chemistry, which is divided int twenty-three chapters. It deals with basic conception and stoichiometry, nature of gas, structure of atoms, quantum mechanics, symbol and structure of an electron of ion and molecule, chemical thermodynamics, nature of solid, change of state and liquid, properties of solution, chemical equilibrium, solution and acid-base, equilibrium of aqueous solution, electrochemistry, chemical reaction speed, molecule spectroscopy, hydrogen, oxygen and water, metallic atom; 1A, IIA, IIIA, carbon and atom IVA, nonmetal atom and an inert gas, transition metals, lanthanons, and actinoids, nuclear properties and radioactivity, biochemistry and environment chemistry.

  7. Radiation chemistry

    Swallow, A.J.

    1983-01-01

    The subject is covered in chapters, entitled: introduction (defines scope of article as dealing with the chemistry of reactive species, (e.g. excess electrons, excited states, free radicals and inorganic ions in unusual valency states) as studied using radiation with radiation chemistry in its traditional sense and with biological and industrial applications); gases; water and simple inorganic systems; aqueous metallo-organic compounds and metalloproteins; small organic molecules in aqueous solution; microheterogeneous systems; non-aqueous liquids and solutions; solids; biological macromolecules; synthetic polymers. (U.K.)

  8. Indoor Chemistry

    Weschler, Charles J.; Carslaw, Nicola

    2018-01-01

    This review aims to encapsulate the importance, ubiquity, and complexity of indoor chemistry. We discuss the many sources of indoor air pollutants and summarize their chemical reactions in the air and on surfaces. We also summarize some of the known impacts of human occupants, who act as sources...... and sinks of indoor chemicals, and whose activities (e.g., cooking, cleaning, smoking) can lead to extremely high pollutant concentrations. As we begin to use increasingly sensitive and selective instrumentation indoors, we are learning more about chemistry in this relatively understudied environment....

  9. Handbook of heterocyclic chemistry

    Katritzky, Alan R

    2010-01-01

    ... Heterocyclic Chemistry I (1984) Comprehensive Heterocyclic Chemistry II (1996) Comprehensive Heterocyclic Chemistry III (2008) Comprehensive Organic Functional Group Transformations I (1995) Compreh...

  10. Control of the Helicity Content of a Gun-Generated Spheromak by Incorporating a Conducting Shell into a Magnetized Coaxial Plasma Gun

    Matsumoto, Tadafumi; Sekiguchi, Jun'ichi; Asai, Tomohiko

    In the formation of magnetized plasmoid by a magnetized coaxial plasma gun (MCPG), the magnetic helicity content of the generated plasmoid is one of the critical parameters. Typically, the bias coil to generate a poloidal flux is mounted either on the outer electrode or inside the inner electrode. However, most of the flux generated in the conventional method spreads even radially outside of the formation region. Thus, only a fraction of the total magnetic flux is actually exploited for helicity generation in the plasmoid. In the proposed system, the plasma gun incorporates a copper shell mounted on the outer electrode. By changing the rise time of the discharge bias coil current and the geometrical structure of the shell, the magnetic field structure and its time evolution can be controlled. The effect of the copper shell has been numerically simulated for the actual gun structure, and experimentally confirmed. This may increase the magnetic helicity content results, through increased poloidal magnetic field.

  11. Reinventing Chemistry

    Whitesides, George McClelland

    2015-01-01

    Chemistry is in a period of change, from an era focused on molecules and reactions, to one in which manipulations of systems of molecules and reactions will be essential parts of controlling larger systems. This Essay traces paths from the past to possible futures.

  12. Chemistry Notes

    School Science Review, 1972

    1972-01-01

    Short articles on the kinetics of the hydrogen peroxide-iodide ion reaction, simulation of fluidization catalysis, the use of Newman projection diagrams to represent steric relationships in organic chemistry, the use of synthetic substrates for proteolytic enzyme reactions, and two simple clock reactions"--hydrolysis of halogenoalkanes and…

  13. Proton magnetic resonance spectroscopy of the frontal, cingulate and perirolandic cortices and its relationship to skin conductance in patients with schizophrenia

    Sanches, R.F.; Crippa, J.A.S.; Hallak, J.E.C.; Sousa, J.P.M. de; Zuardi, A.W. [Universidade de Sao Paulo (USP), Ribeirao Preto, SP, (Brazil). Faculdade de Medicina. Dept. de Neurociencias e Ciencias do Comportamento]. E-mail: awzuardi@fmrp.usp.br; Araujo, D.; Santos, A.C. [Universidade de Sao Paulo (USP), Ribeirao Preto, SP, (Brazil). Faculdade de Medicina. Div. de Radiologia

    2008-07-01

    The aim of the present study was to determine whether specific subgroups of schizophrenic patients, grouped according to electrodermal characteristics, show differences in the N-acetylaspartate/creatine plus choline (NAA / (Cr + Cho)) ratios in the frontal, cingulate and perirolandic cortices. Skin conductance levels (SCL) and skin conductance responses to auditory stimulation were measured in 38 patients with schizophrenia and in the same number of matched healthy volunteers (control). All subjects were submitted to multivoxel proton magnetic resonance spectroscopic imaging. When compared to the control group, patients presented significantly lower NAA / (Cr + Cho) ratios in the right dorsolateral prefrontal cortex (schizophrenia 0.95 {+-} 0.03; control = 1.12 {+-} 0.04) and in the right (schizophrenia 0.88 {+-} 0.02; control = 0.94 {+-} 0.03) and left (schizophrenia 0.84 {+-} 0.03; control = 0.94 {+-} 0.03) cingulates. These ratios did not differ between electrodermally responsive and non-responsive patients. When patients were divided into two groups: lower SCL (less than the mean SCL of the control group minus two standard deviations) and normal SCL (similar to the control group), the subgroup with a lower level of SCL showed a lower NAA / (Cr + Cho) ratio in the left cingulate (0.78 {+-} 0.05) than the controls (0.95 {+-} 0.02, P < 0.05) and the subgroup with normal SCL (0.88 {+-} 0.03, P < 0.05). There was a negative correlation between the NAA / (Cr + Cho) ratio in the left cingulate of patients with schizophrenia and the duration of the disease and years under medication. These data suggest the existence of a schizophrenic subgroup characterized by low SCL that could be a consequence of the lower neuronal viability observed in the left cingulate of these patients. (author)

  14. Proton magnetic resonance spectroscopy of the frontal, cingulate and perirolandic cortices and its relationship to skin conductance in patients with schizophrenia

    Sanches, R.F.; Crippa, J.A.S.; Hallak, J.E.C.; Sousa, J.P.M. de; Zuardi, A.W.; Araujo, D.; Santos, A.C.

    2008-01-01

    The aim of the present study was to determine whether specific subgroups of schizophrenic patients, grouped according to electrodermal characteristics, show differences in the N-acetylaspartate/creatine plus choline (NAA / (Cr + Cho)) ratios in the frontal, cingulate and perirolandic cortices. Skin conductance levels (SCL) and skin conductance responses to auditory stimulation were measured in 38 patients with schizophrenia and in the same number of matched healthy volunteers (control). All subjects were submitted to multivoxel proton magnetic resonance spectroscopic imaging. When compared to the control group, patients presented significantly lower NAA / (Cr + Cho) ratios in the right dorsolateral prefrontal cortex (schizophrenia 0.95 ± 0.03; control = 1.12 ± 0.04) and in the right (schizophrenia 0.88 ± 0.02; control = 0.94 ± 0.03) and left (schizophrenia 0.84 ± 0.03; control = 0.94 ± 0.03) cingulates. These ratios did not differ between electrodermally responsive and non-responsive patients. When patients were divided into two groups: lower SCL (less than the mean SCL of the control group minus two standard deviations) and normal SCL (similar to the control group), the subgroup with a lower level of SCL showed a lower NAA / (Cr + Cho) ratio in the left cingulate (0.78 ± 0.05) than the controls (0.95 ± 0.02, P < 0.05) and the subgroup with normal SCL (0.88 ± 0.03, P < 0.05). There was a negative correlation between the NAA / (Cr + Cho) ratio in the left cingulate of patients with schizophrenia and the duration of the disease and years under medication. These data suggest the existence of a schizophrenic subgroup characterized by low SCL that could be a consequence of the lower neuronal viability observed in the left cingulate of these patients. (author)

  15. Physical chemistry II essentials

    REA, The Editors of

    1992-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Physical Chemistry II includes reaction mechanisms, theoretical approaches to chemical kinetics, gravitational work, electrical and magnetic work, surface work, kinetic theory, collisional and transport properties of gases, statistical mechanics, matter and waves, quantum mechanics, and rotations and vibrations of atoms and molecules.

  16. Chemistry-Nuclear Chemistry Division. Progress report, October 1980-September 1981

    Ryan, R.R.

    1982-05-01

    This report describes major progress in the research and development programs pursued by the Chemistry-Nuclear Chemistry Division of the Los Alamos National Laboratory during FY 1981. Topics covered include advanced analytical methods, atmospheric chemistry and transport, biochemistry, biomedical research, medical radioisotopes research, element migration and fixation, nuclear waste isolation research, inorganic and structural chemistry, isotope separation, analysis and applications, the newly established Nuclear Magnetic Resonance Center, atomic and molecular collisions, molecular spectroscopy, nuclear cosmochemistry, nuclear structure and reactions, pion charge exchange, radiochemical separations, theoretical chemistry, and unclassified weapons research

  17. Chemistry-Nuclear Chemistry Division. Progress report, October 1980-September 1981

    Ryan, R.R. (comp.)

    1982-05-01

    This report describes major progress in the research and development programs pursued by the Chemistry-Nuclear Chemistry Division of the Los Alamos National Laboratory during FY 1981. Topics covered include advanced analytical methods, atmospheric chemistry and transport, biochemistry, biomedical research, medical radioisotopes research, element migration and fixation, nuclear waste isolation research, inorganic and structural chemistry, isotope separation, analysis and applications, the newly established Nuclear Magnetic Resonance Center, atomic and molecular collisions, molecular spectroscopy, nuclear cosmochemistry, nuclear structure and reactions, pion charge exchange, radiochemical separations, theoretical chemistry, and unclassified weapons research.

  18. Magnetic properties of high-Ti basaltic rocks from the Krušné hory/Erzgebirge Mts. (Bohemia/Saxony), and their relation to mineral chemistry

    Schnabl, Petr; Novák, Jiří Karel; Cajz, Vladimír; Lang, Miloš; Balogh, K.; Pécskay, Z.; Chadima, Martin; Šlechta, Stanislav; Kohout, Tomáš; Pruner, Petr; Ulrych, Jaromír

    2010-01-01

    Roč. 54, č. 1 (2010), s. 77-94 ISSN 0039-3169 R&D Projects: GA AV ČR IAA300130706 Institutional research plan: CEZ:AV0Z30130516 Keywords : high-Ti basaltic rocks * magnetic petrology * thermomagnetic experiments * Curie temperature variation * field-dependent susceptibility * Ohře/Eger Rift Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 1.123, year: 2010

  19. Computer simulation and experimental self-assembly of irradiated glycine amino acid under magnetic fields: Its possible significance in prebiotic chemistry.

    Heredia, Alejandro; Colín-García, María; Puig, Teresa Pi I; Alba-Aldave, Leticia; Meléndez, Adriana; Cruz-Castañeda, Jorge A; Basiuk, Vladimir A; Ramos-Bernal, Sergio; Mendoza, Alicia Negrón

    2017-12-01

    Ionizing radiation may have played a relevant role in chemical reactions for prebiotic biomolecule formation on ancient Earth. Environmental conditions such as the presence of water and magnetic fields were possibly relevant in the formation of organic compounds such as amino acids. ATR-FTIR, Raman, EPR and X-ray spectroscopies provide valuable information about molecular organization of different glycine polymorphs under static magnetic fields. γ-glycine polymorph formation increases in irradiated samples interacting with static magnetic fields. The increase in γ-glycine polymorph agrees with the computer simulations. The AM1 semi-empirical simulations show a change in the catalyst behavior and dipole moment values in α and γ-glycine interaction with the static magnetic field. The simulated crystal lattice energy in α-glycine is also affected by the free radicals under the magnetic field, which decreases its stability. Therefore, solid α and γ-glycine containing free radicals under static magnetic fields might have affected the prebiotic scenario on ancient Earth by causing the oligomerization of glycine in prebiotic reactions. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Chemistry and physics

    Broerse, J.J.; Barendsen, G.W.; Kal, H.B.; Kogel, A.J. van der

    1983-01-01

    This book contains the extended abstracts of the contributions of the poster workshop sessions on chemistry and physics of the 7th international congress of radiation research. They cover the following main topics: primary processes in radiation physics and chemistry, general chemistry in radiation chemistry, DNA and model systems in radiation chemistry, molecules of biological interest in radiation chemistry, techniques in radiation chemistry, hot atom chemistry. refs.; figs.; tabs

  1. National Chemistry Teacher Safety Survey

    Plohocki, Barbra A.

    This study evaluated the status of secondary school instructional chemistry laboratory safety using a survey instrument which focused on Teacher background Information, Laboratory Safety Equipment, Facility Safety, General Safety, and a Safety Content Knowledge Survey. A fifty question survey instrument based on recent research and questions developed by the researcher was mailed to 500 secondary school chemistry teachers who participated in the 1993 one-week Woodrow Wilson National Fellowship Foundation Chemistry Institute conducted at Princeton University, New Jersey. The data received from 303 respondents was analyzed by t tests and Analysis of Variance (ANOVA). The level of significance for the study was set at ~\\ performance on the Safety Content Knowledge Survey and secondary school chemistry teachers who have had undergraduate and/or graduate safety training and those who have not had undergraduate and/or graduate safety training. Secondary school chemistry teachers who attended school district sponsored safety inservices did not score higher on the Safety Content Knowledge Survey than teachers who did not attend school district sponsored safety inservice sessions. The type of school district (urban, suburban, or rural) had no significant correlation to the type of laboratory safety equipment found in the instructional chemistry laboratory. The certification area (chemistry or other type of certificate which may or may not include chemistry) of the secondary school teacher had no significant correlation to the type of laboratory equipment found in the instructional chemistry laboratory. Overall, this study indicated a majority of secondary school chemistry teachers were interested in attending safety workshops applicable to chemistry safety. Throughout this research project, many teachers indicated they were not adequately instructed on the collegiate level in science safety and had to rely on common sense and self-study in their future teaching careers.

  2. Fine chemistry

    Laszlo, P.

    1988-01-01

    The 1988 progress report of the Fine Chemistry laboratory (Polytechnic School, France) is presented. The research programs are centered on the renewal of the organic chemistry most important reactions and on the invention of new, highly efficient and highly selective reactions, by applying low cost reagents and solvents. An important research domain concerns the study and fabrication of new catalysts. They are obtained by means of the reactive sputtering of the metals and metal oxydes thin films. The Monte Carlo simulations of the long-range electrostatic interaction in a clay and the obtention of acrylamides from anhydrous or acrylic ester are summarized. Moreover, the results obtained in the field of catalysis are also given. The published papers and the congress communications are included [fr

  3. Radioanalytical chemistry

    1982-01-01

    The bibliography of Hungarian literature in the field of radioanalytical chemistry covers the four-year period 1976-1979. The list of papers contains 290 references in the alphabetical order of the first authors. The majority of the titles belongs to neutron activation analysis, labelling, separation and determination of radioactive isotopes. Other important fields like radioimmunoassay, environmental protection etc. are covered as well. (Sz.J.)

  4. Analytical chemistry

    Anon.

    1985-01-01

    The division for Analytical Chemistry continued to try and develope an accurate method for the separation of trace amounts from mixtures which, contain various other elements. Ion exchange chromatography is of special importance in this regard. New separation techniques were tried on certain trace amounts in South African standard rock materials and special ceramics. Methods were also tested for the separation of carrier-free radioisotopes from irradiated cyclotron discs

  5. Industrial chemistry engineering

    1993-01-01

    This book on industrial chemistry engineering is divided in two parts. The first part deals with industrial chemistry, inorganic industrial chemistry, organic industrial chemistry, analytical chemistry and practical questions. The last parts explain the chemical industry, a unit parts and thermodynamics in chemical industry and reference. It reveals the test subjects for the industrial chemistry engineering with a written examination and practical skill.

  6. Computational chemistry

    Arnold, J. O.

    1987-01-01

    With the advent of supercomputers, modern computational chemistry algorithms and codes, a powerful tool was created to help fill NASA's continuing need for information on the properties of matter in hostile or unusual environments. Computational resources provided under the National Aerodynamics Simulator (NAS) program were a cornerstone for recent advancements in this field. Properties of gases, materials, and their interactions can be determined from solutions of the governing equations. In the case of gases, for example, radiative transition probabilites per particle, bond-dissociation energies, and rates of simple chemical reactions can be determined computationally as reliably as from experiment. The data are proving to be quite valuable in providing inputs to real-gas flow simulation codes used to compute aerothermodynamic loads on NASA's aeroassist orbital transfer vehicles and a host of problems related to the National Aerospace Plane Program. Although more approximate, similar solutions can be obtained for ensembles of atoms simulating small particles of materials with and without the presence of gases. Computational chemistry has application in studying catalysis, properties of polymers, all of interest to various NASA missions, including those previously mentioned. In addition to discussing these applications of computational chemistry within NASA, the governing equations and the need for supercomputers for their solution is outlined.

  7. Green chemistry

    Warner, John C.; Cannon, Amy S.; Dye, Kevin M.

    2004-01-01

    A grand challenge facing government, industry, and academia in the relationship of our technological society to the environment is reinventing the use of materials. To address this challenge, collaboration from an interdisciplinary group of stakeholders will be necessary. Traditionally, the approach to risk management of materials and chemicals has been through inerventions intended to reduce exposure to materials that are hazardous to health and the environment. In 1990, the Pollution Prevention Act encouraged a new tact-elimination of hazards at the source. An emerging approach to this grand challenge seeks to embed the diverse set of environmental perspectives and interests in the everyday practice of the people most responsible for using and creating new materials--chemists. The approach, which has come to be known as Green Chemistry, intends to eliminate intrinsic hazard itself, rather than focusing on reducing risk by minimizing exposure. This chapter addresses the representation of downstream environmental stakeholder interests in the upstream everyday practice that is reinventing chemistry and its material inputs, products, and waste as described in the '12 Principles of Green Chemistry'

  8. Uranium chemistry: significant advances

    Mazzanti, M.

    2011-01-01

    The author reviews recent progress in uranium chemistry achieved in CEA laboratories. Like its neighbors in the Mendeleev chart uranium undergoes hydrolysis, oxidation and disproportionation reactions which make the chemistry of these species in water highly complex. The study of the chemistry of uranium in an anhydrous medium has led to correlate the structural and electronic differences observed in the interaction of uranium(III) and the lanthanides(III) with nitrogen or sulfur molecules and the effectiveness of these molecules in An(III)/Ln(III) separation via liquid-liquid extraction. Recent work on the redox reactivity of trivalent uranium U(III) in an organic medium with molecules such as water or an azide ion (N 3 - ) in stoichiometric quantities, led to extremely interesting uranium aggregates particular those involved in actinide migration in the environment or in aggregation problems in the fuel processing cycle. Another significant advance was the discovery of a compound containing the uranyl ion with a degree of oxidation (V) UO 2 + , obtained by oxidation of uranium(III). Recently chemists have succeeded in blocking the disproportionation reaction of uranyl(V) and in stabilizing polymetallic complexes of uranyl(V), opening the way to to a systematic study of the reactivity and the electronic and magnetic properties of uranyl(V) compounds. (A.C.)

  9. Theoretical chemistry periodicities in chemistry and biology

    Eyring, Henry

    1978-01-01

    Theoretical Chemistry: Periodicities in Chemistry and Biology, Volume 4 covers the aspects of theoretical chemistry. The book discusses the stably rotating patterns of reaction and diffusion; the chemistry of inorganic systems exhibiting nonmonotonic behavior; and population cycles. The text also describes the mathematical modeling of excitable media in neurobiology and chemistry; oscillating enzyme reactions; and oscillatory properties and excitability of the heart cell membrane. Selected topics from the theory of physico-chemical instabilities are also encompassed. Chemists, mechanical engin

  10. Solution chemistry

    None

    1973-07-01

    Research progress is reported on studies in heavy element chemistry. Topics considered are: synergistic complexes of plutonyl ion; water uptake in synergistic systems; formation constants of some uranyl BETA -diketone complexes; thermodynamic acid dissociation constants of BETA -diketones; thermodynamic formation constants of uranyl BETA -diketonates; thiocyanate complexes of some trivalent lanthanides and actinides; stability constants of actinide complexes using dinonyl naphthalenesulfonic acid extraction; TBP extraction of actinides; stability constants of complexes of Pu(III) with 5- sulfosalicycllc acid; and solvent extraction behavior of Pu( VII). (DHM)

  11. Interstellar chemistry.

    Klemperer, William

    2006-08-15

    In the past half century, radioastronomy has changed our perception and understanding of the universe. In this issue of PNAS, the molecular chemistry directly observed within the galaxy is discussed. For the most part, the description of the molecular transformations requires specific kinetic schemes rather than chemical thermodynamics. Ionization of the very abundant molecular hydrogen and atomic helium followed by their secondary reactions is discussed. The rich variety of organic species observed is a challenge for complete understanding. The role and nature of reactions involving grain surfaces as well as new spectroscopic observations of interstellar and circumstellar regions are topics presented in this special feature.

  12. Investigation of ULF magnetic pulsations, air conductivity changes, and infra red signatures associated with the 30 October Alum Rock M5.4 earthquake

    T. Bleier

    2009-04-01

    ionization reported to be associated with radon emission from the ground (Ouzounov, 2007, and a series of laboratory rock stressing experiments (Freund, 2006, 2007a, b, c to determine if field data was consistent either of these accounts. We could not find a data set with pre-earthquake radon measurements taken near the Alum Rock epicenter to compare against our field data. However, based on the Alum Rock data set example and another data set at Parkfield, the field tests are at least consistent with the lab experiments showing currents, magnetic field disturbances, air conductivity changes, and IR signatures. This is encouraging, but more instrumented earthquake examples are needed to prove a repeating pattern for these types of pre-earthquake EM signatures.

  13. BWR chromium chemistry

    Baston, V.F.; Indig, M.E.; Skarpelos, J.M.

    1992-10-01

    This report addresses the concern about higher total specific conductivity in the reactor recirculation loop water due to the chromate ion. This concern is particularly high at plants where all other ionic species have been reduced through careful attention to makeup and condensate polisher operations. An EPRI Chromate Workshop was held in November 1990 to consider the issues raised by observed levels of chromate ion (generally 5 to 50 ppB). While BWRs on normal water chemistry were the only ones observing chromate, even plants on hydrogen water chemistry (HWC) observe sharp spikes of conductivity due to chromate whenever the hydrogen supply was interrupted after a reasonably long HWC operational period. The consensus of the workshop attendees was that chromate was not a concern as an agent causing pipe cracking compared to the more common species such as chloride and sulfate. However, the data are somewhat ambiguous for levels of chromate above 50 ppB. Adjustments to the weighing factors for the various ionic species in the industry chemistry performance index are suggested to allow for the known relative higher aggressiveness of other species relative to that of chromate

  14. Radiation chemistry and bioradical chemistry

    Ferradini, C.

    1991-01-01

    Oxygen metabolism results, at the cellular level, in the formation of superoxyde radical O 2 - · and probably also of hydroxyl radical OH·. Other radical species can be produced from exogenous or endogenous molecules and nearly all of them have the possibility to react with oxygen giving peroxyradicals. Some of these transients play a role in various biological processes such as phagocytosis, inflammation or ischemy although the mechanisms invoked are poorly understood. Radiation chemistry is an invaluable tool for obtaining a quantitative view of these mechanisms. A description is given of this interaction [fr

  15. Fundamentals of nuclear chemistry

    Majer, K.

    1982-01-01

    The textbook is a Czech-to-German translation of the second revised edition and covers the subject under the headings: general nuclear chemistry, methods of nuclear chemistry, preparative nuclear chemistry, analytical nuclear chemistry, and applied chemistry. The book is especially directed to students

  16. Cyclodextrin chemistry

    Khan, M.Z.; Chuaqui, C.A.

    1990-05-01

    The chemistry of cyclodextrins was studied. This study included synthesising some cyclodextrin derivatives, preparing selected inclusion complexes with cyclodextrin and investigating the effects of gamma irradiation on cyclodextrins and certain linear oligosaccharides. This report presents a brief review of the structure and properties of cyclodextrins, the synthesis of cyclodextrin derivatives, their complexation and applications. This is followed by a description of the synthesis of some cyclodextrin derivatives and the preparation of inclusion complexes of cyclodextrin with some organic compounds. Finally, the effects of gamma irradiation on cyclodextrins, some of their derivatives and certain structurally related carbohydrates are discussed. The gamma irradiation studies were carried out for two reasons: to study the effects of gamma irradiation on cyclodextrins and their derivatives; and to investigate selectivity during the gamma irradiation of cyclodextrin derivatives

  17. Astronomical chemistry.

    Klemperer, William

    2011-01-01

    The discovery of polar polyatomic molecules in higher-density regions of the interstellar medium by means of their rotational emission detected by radioastronomy has changed our conception of the universe from essentially atomic to highly molecular. We discuss models for molecule formation, emphasizing the general lack of thermodynamic equilibrium. Detailed chemical kinetics is needed to understand molecule formation as well as destruction. Ion molecule reactions appear to be an important class for the generally low temperatures of the interstellar medium. The need for the intrinsically high-quality factor of rotational transitions to definitively pin down molecular emitters has been well established by radioastronomy. The observation of abundant molecular ions both positive and, as recently observed, negative provides benchmarks for chemical kinetic schemes. Of considerable importance in guiding our understanding of astronomical chemistry is the fact that the larger molecules (with more than five atoms) are all organic.

  18. Reburning chemistry

    Kilpin, P.; Hupa, M.; Glarborg, P.

    1992-01-01

    No reduction chemistry in natural gas (methane) reburning was studied using detailed kinetic modeling. A reaction set including 225 reversible elementary gas-phase reactions and 48 chemical species was applied to an ideal plug flow reactor, and the most important reactions leading to NO reduction were identified and quantified for a number of conditions relevant for natural gas reburning. In addition, the influence of different process parameters on the NO reduction was investigated in the reburn zone and burn-out zone, respectively. Further, comparison of the calculations to available laboratory-scale data on reburning is made. In this paper, the impact of various fluid dynamic, mixing, and chemical effects---not accounted for in the calculations---on the NO reduction and the optimum reburning conditions predicted is discussed

  19. Combustion chemistry

    Brown, N.J. [Lawrence Berkeley Laboratory, CA (United States)

    1993-12-01

    This research is concerned with the development and use of sensitivity analysis tools to probe the response of dependent variables to model input variables. Sensitivity analysis is important at all levels of combustion modeling. This group`s research continues to be focused on elucidating the interrelationship between features in the underlying potential energy surface (obtained from ab initio quantum chemistry calculations) and their responses in the quantum dynamics, e.g., reactive transition probabilities, cross sections, and thermal rate coefficients. The goals of this research are: (i) to provide feedback information to quantum chemists in their potential surface refinement efforts, and (ii) to gain a better understanding of how various regions in the potential influence the dynamics. These investigations are carried out with the methodology of quantum functional sensitivity analysis (QFSA).

  20. Chemistry Laboratory

    Federal Laboratory Consortium — Purpose: To conduct fundamental studies of highway materials aimed at understanding both failure mechanisms and superior performance. New standard test methods are...

  1. Quantum chemistry and scientific calculus

    Gervais, H.P.

    1988-01-01

    The 1988 progress report of the Polytechnic School research team, concerning the quantum chemistry and the scientific calculus. The research program involves the following topics: the transition metals - carbon monoxide systems, which are a suitable model for the chemisorption phenomena; the introduction of the vibronic perturbations in the magnetic screen constants; the gauge invariance method (used in the calculation of the magnetic perturbations), extended to the case of the static or dynamic electrical polarizabilities. The published papers, the congress communications and the thesis are listed [fr

  2. Polyaniline–maghemite based dispersion: electrical, magnetic properties and their cytotoxicity

    Bober, Patrycja; Zasońska, Beata Anna; Humpolíček, P.; Kuceková, Z.; Varga, M.; Horák, Daniel; Babayan, V.; Kazantseva, N.; Prokeš, J.; Stejskal, Jaroslav

    2016-01-01

    Roč. 214, April (2016), s. 23-29 ISSN 0379-6779 R&D Projects: GA ČR(CZ) GP14-05568P; GA MŠk(CZ) LH14318 Institutional support: RVO:61389013 Keywords : conducting polymer * magnetic dispersion * polyaniline Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.435, year: 2016

  3. Why Teach Environmental Chemistry?

    Gardner, Marjorie H.

    1974-01-01

    Discusses the importance of teaching environmental chemistry in secondary school science classes, and outlines five examples of environmental chemistry problems that focus on major concepts of chemistry and have critical implications for human survival and well-being. (JR)

  4. Structural chemistry and magnetic properties of the perovskite Sr{sub 3}Fe{sub 2}TeO{sub 9}

    Tang, Yawei; Hunter, Emily C. [Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR (United Kingdom); Battle, Peter D., E-mail: peter.battle@chem.ox.ac.uk [Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR (United Kingdom); Sena, Robert Paria; Hadermann, Joke [EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium); Avdeev, Maxim [Bragg Institute, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234 (Australia); Cadogan, J.M. [School of Physical, Environmental and Mathematical Sciences, UNSW Canberra at the Australian Defence Force Academy, Canberra BC 2610 (Australia)

    2016-10-15

    A polycrystalline sample of perovskite-like Sr{sub 3}Fe{sub 2}TeO{sub 9} has been prepared in a solid-state reaction and studied by a combination of electron microscopy, Mössbauer spectroscopy, magnetometry, X-ray diffraction and neutron diffraction. The majority of the reaction product is shown to be a trigonal phase with a 2:1 ordered arrangement of Fe{sup 3+} and Te{sup 6+} cations. However, the sample is prone to nano-twinning and tetragonal domains with a different pattern of cation ordering exist within many crystallites. Antiferromagnetic ordering exists in the trigonal phase at 300 K and Sr{sub 3}Fe{sub 2}TeO{sub 9} is thus the first example of a perovskite with 2:1 trigonal cation ordering to show long-range magnetic order. At 300 K the antiferromagnetic phase coexists with two paramagnetic phases which show spin-glass behaviour below ~80 K. - Graphical abstract: Sr{sub 3}Fe{sub 2}TeO{sub 9} has a 2:1 ordered arrangement of Fe{sup 3+} and Te{sup 6+} cations over the octahedral sites of a perovskite structure and is antiferromagnetic at room temperature. - Highlights: • 2:1 Cation ordering in a trigonal perovskite. • Magnetically ordered trigonal perovskite. • Intergrowth of nanodomains in perovskite microstructure.

  5. Interplay of structural chemistry and magnetism in perovskites; A study of CaLn2Ni2WO9; Ln=La, Pr, Nd

    Chin, Chun-Mann; Paria Sena, Robert; Hunter, Emily C.; Hadermann, Joke; Battle, Peter D.

    2017-07-01

    Polycrystalline samples of CaLn2Ni2WO9 (Ln=La, Pr, Nd) have been synthesized and characterised by a combination of X-ray and neutron diffraction, electron microscopy and magnetometry. Each composition adopts a perovskite-like structure with a 5.50, b 5.56, c 7.78 Å, β 90.1° in space group P21/n. Of the two crystallographically distinct six-coordinate sites, one is occupied entirely (Ln=Pr) or predominantly (Ln=La, Nd) by Ni2+ and the other by Ni2+ and W6+ in a ratio of approximately 1:2. None of the compounds shows long-range magnetic order at 5 K. The magnetometry data show that the magnetic moments of the Ni2+ cations form a spin glass below 30 K in each case. The Pr3+ moments in CaPr2Ni2WO9 also freeze but the Nd3+ moments in CaNd2Ni2WO9 do not. This behaviour is contrasted with that observed in other (A,A')B2B'O9 perovskites.

  6. Mendeleev-2013. VII All-Russian conference of young scientists, postgraduate students and students with international participation on chemistry and nanomaterials. Book of abstracts. Section 4. Organic chemistry

    2013-01-01

    VII All-Russian conference of young scientists, postgraduate students and students with international participation on chemistry and nanomaterials was conducted on the Chemistry department of Saint-Petersburg University on April, 2-5, 2013. In the conference participants from 14 countries took part. There were five sections: Nanochemistry and nanomaterials, Analytic chemistry, Inorganic chemistry, Organic chemistry, Physical chemistry. In the collection (Section 2 - Organic chemistry) there are the abstracts concerning different aspects of organic chemistry: synthesis and study of properties of heterocyclic, organometallic, biologically active, medicinal compounds, new ion exchange materials, reagents for analytic chemistry, etc [ru

  7. Environmental chemistry. Seventh edition

    Manahan, S.E. [Univ. of Missouri, Columbia, MO (United States)

    1999-11-01

    This book presents a basic understanding of environmental chemistry and its applications. In addition to providing updated materials in this field, the book emphasizes the major concepts essential to the practice of environmental chemistry. Topics of discussion include the following: toxicological chemistry; toxicological chemistry of chemical substances; chemical analysis of water and wastewater; chemical analysis of wastes and solids; air and gas analysis; chemical analysis of biological materials and xenobiotics; fundamentals of chemistry; and fundamentals of organic chemistry.

  8. Hysteresis in conducting ferromagnets

    Schneider, Carl S.; Winchell, Stephen D.

    2006-01-01

    Maxwell's magnetic diffusion equation is solved for conducting ferromagnetic cylinders to predict a magnetic wave velocity, a time delay for flux penetration and an eddy current field, one of five fields in the linear unified field model of hysteresis. Measured Faraday voltages for a thin steel toroid are shown to be proportional to magnetic field step amplitude and decrease exponentially in time due to maximum rather than average permeability. Dynamic permeabilities are a field convolution of quasistatic permeability and the delay function from which we derive and observe square root dependence of coercivity on rate of field change

  9. USSR Report Chemistry

    1986-01-01

    Contents: Adsorption, Chemistry,Alkaloids, Analytical Chemistry, Catalysis,Chemical Industry,,Coal Gasification, Combustion, Electrochemistry,Explosives and Explosions, Fertilizers, Free Radicals, Inorganic...

  10. Itinerant ferromagnetism in the As 4p conduction band of Ba_{0.6}K_{0.4}Mn_{2}As_{2} identified by X-ray magnetic circular dichroism.

    Ueland, B G; Pandey, Abhishek; Lee, Y; Sapkota, A; Choi, Y; Haskel, D; Rosenberg, R A; Lang, J C; Harmon, B N; Johnston, D C; Kreyssig, A; Goldman, A I

    2015-05-29

    X-ray magnetic circular dichroism (XMCD) measurements on single-crystal and powder samples of Ba_{0.6}K_{0.4}Mn_{2}As_{2} show that the ferromagnetism below T_{C}≈100  K arises in the As 4p conduction band. No XMCD signal is observed at the Mn x-ray absorption edges. Below T_{C}, however, a clear XMCD signal is found at the As K edge which increases with decreasing temperature. The XMCD signal is absent in data taken with the beam directed parallel to the crystallographic c axis indicating that the orbital magnetic moment lies in the basal plane of the tetragonal lattice. These results show that the previously reported itinerant ferromagnetism is associated with the As 4p conduction band and that distinct local-moment antiferromagnetism and itinerant ferromagnetism with perpendicular easy axes coexist in this compound at low temperature.

  11. Predictive Modeling in Actinide Chemistry and Catalysis

    Yang, Ping [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-16

    These are slides from a presentation on predictive modeling in actinide chemistry and catalysis. The following topics are covered in these slides: Structures, bonding, and reactivity (bonding can be quantified by optical probes and theory, and electronic structures and reaction mechanisms of actinide complexes); Magnetic resonance properties (transition metal catalysts with multi-nuclear centers, and NMR/EPR parameters); Moving to more complex systems (surface chemistry of nanomaterials, and interactions of ligands with nanoparticles); Path forward and conclusions.

  12. Establishment of reference intervals of clinical chemistry analytes for the adult population in Saudi Arabia: a study conducted as a part of the IFCC global study on reference values.

    Borai, Anwar; Ichihara, Kiyoshi; Al Masaud, Abdulaziz; Tamimi, Waleed; Bahijri, Suhad; Armbuster, David; Bawazeer, Ali; Nawajha, Mustafa; Otaibi, Nawaf; Khalil, Haitham; Kawano, Reo; Kaddam, Ibrahim; Abdelaal, Mohamed

    2016-05-01

    This study is a part of the IFCC-global study to derive reference intervals (RIs) for 28 chemistry analytes in Saudis. Healthy individuals (n=826) aged ≥18 years were recruited using the global study protocol. All specimens were measured using an Architect analyzer. RIs were derived by both parametric and non-parametric methods for comparative purpose. The need for secondary exclusion of reference values based on latent abnormal values exclusion (LAVE) method was examined. The magnitude of variation attributable to gender, ages and regions was calculated by the standard deviation ratio (SDR). Sources of variations: age, BMI, physical exercise and smoking levels were investigated by using the multiple regression analysis. SDRs for gender, age and regional differences were significant for 14, 8 and 2 analytes, respectively. BMI-related changes in test results were noted conspicuously for CRP. For some metabolic related parameters the ranges of RIs by non-parametric method were wider than by the parametric method and RIs derived using the LAVE method were significantly different than those without it. RIs were derived with and without gender partition (BMI, drugs and supplements were considered). RIs applicable to Saudis were established for the majority of chemistry analytes, whereas gender, regional and age RI partitioning was required for some analytes. The elevated upper limits of metabolic analytes reflects the existence of high prevalence of metabolic syndrome in Saudi population.

  13. Water chemistry

    Hofstetter, K.J.; Baston, V.F.

    1986-01-01

    Prior to the accident, the coolants in the primary and secondary systems were within normal chemistry specifications for an operating pressurized water reactor with once-through steam generators. During and immediately after the accident, additional boric acid and sodium hydroxide were added to the primary coolant for control of criticality and radioiodine solubility. A primary to secondary leak developed contaminating the water in one steam generator. For about 5 years after the accident, the primary coolant was maintained at 3800 +. 100 ppm boron and 1000 +. 100 ppm sodium concentrations. Dissolved oxygen was maintained 7.5, corrosion caused by increased dissolved oxygen levels (up to 8 ppm) and higher chloride ion content (up to 5 ppm) is minimized. Chemical control of dissolved oxygen was discontinued and the coolant was processed. Prior to removal of the reactor vessel head, the boron concentration in the coolant was increased to ≅ 5000 ppm to support future defueling operations. Decontamination of the accident generated water is described in terms of contaminated water management. In addition, the decontamination and chemical lay-up conditions for the secondary system are presented along with an overview of chemical management at TMI-2

  14. Migration chemistry

    Carlsen, L.

    1992-05-01

    Migration chemistry, the influence of chemical -, biochemical - and physico-chemical reactions on the migration behaviour of pollutants in the environment, is an interplay between the actual natur of the pollutant and the characteristics of the environment, such as pH, redox conditions and organic matter content. The wide selection of possible pollutants in combination with varying geological media, as well as the operation of different chemical -, biochemical - and physico-chemical reactions compleactes the prediction of the influence of these processes on the mobility of pollutants. The report summarizes a wide range of potential pollutants in the terrestrial environment as well as a variety of chemical -, biochemical - and physico-chemical reactions, which can be expected to influence the migration behaviour, comprising diffusion, dispersion, convection, sorption/desorption, precipitation/dissolution, transformations/degradations, biochemical reactions and complex formation. The latter comprises the complexation of metal ions as well as non-polar organics to naturally occurring organic macromolecules. The influence of the single types of processes on the migration process is elucidated based on theoretical studies. The influence of chemical -, biochemical - and physico-chemical reactions on the migration behaviour is unambiguous, as the processes apparently control the transport of pollutants in the terrestrial environment. As the simple, conventional K D concept breaks down, it is suggested that the migration process should be described in terms of the alternative concepts chemical dispersion, average-elution-time and effective retention. (AB) (134 refs.)

  15. Chemistry of the actinide elements. Second edition

    Katz, J.J.; Seaborg, G.T.; Morss, L.R.

    1987-01-01

    This is an exhaustive, updated discourse on the chemistry of Actinides, Volume 1 contains a systematic coverage of the elements Ac, Th, Pa, U, Np, and Pu, which constitutes Part 1 of the work. The characterization of each element is discussed in terms of its nuclear properties, occurrence, preparation, atomic and metallic properties, chemistry of specific compounds, and solution chemistry. The first part of Volume 2 follows the same format as Volume 1 but is confined to the elements Am, Cm, Bk, Cf, and Es, plus a more condensed coverage of the Transeinsteinium elements (Fm, Md, No, Lw, and 104-109). Part 2 of this volume is devoted to a discussion of the actinide elements in general, with a specific focus on electronic spectra, thermodynamic and magnetic properties, the metallic state, structural chemistry, solution kinetics, organometallic chemistry for σ- and π-bonded compounds, and some concluding remarks on the superheavy elements

  16. A Concept for the Use and Integration of Super-Conducting Magnets in Structural Systems in General and Maglev Guideway Mega-Structures in Particular

    Ussery, Wilfred T.; MacCalla, Eric; MacCalla, Johnetta; Elnimeiri, Mahjoub; Goldsmith, Myron; Polk, Sharon Madison; Jenkins, Mozella; Bragg, Robert H.

    1996-01-01

    Recent breakthroughs in several different fields now make it possible to incorporate the use of superconducting magnets in structures in ways which enhance the performance of structural members or components of structural systems in general and Maglev guideway mega-structures in particular. The building of structural systems which connect appropriately scaled superconducting magnets with the post-tensioned tensile components of beams, girders, or columns would, if coupled with 'state of the art' structure monitoring, feedback and control systems, and advanced computer software, constitute a distinct new generation of structures that would possess the unique characteristic of being heuristic and demand or live-load responsive. The holistic integration of powerful superconducting magnets in structures so that they do actual structural work, creates a class of 'technologically endowed' structures that, in part - literally substitute superconductive electric power and magnetism for concrete and steel. The research and development engineering, and architectural design issues associated with such 'technologically endowed' structural system can now be conceptualized, designed, computer simulates built and tested. The Maglev guideway mega-structure delineated herein incorporates these concepts, and is designed for operation in the median strip of U.S. Interstate Highway 5 from San Diego to Seattle an Vancouver, and possibly on to Fairbanks, Alaska. This system also fits in the median strip of U.S. Interstate Highway 55 and 95 North-South, and 80 and 10, East-West. As a Western Region 'Peace Dividend' project, it could become a National or Bi-National research, design and build, super turnkey project that would create thousands of jobs by applying superconducting, material science, electronic aerospace and other defense industry technologies to a multi-vehicle, multi-use Maglev guideway megastructure that integrates urban mass transit Lower Speed (0-100 mph), High Speed

  17. Structural chemistry and magnetic properties of the perovskite SrLa{sub 2}Ni{sub 2}TeO{sub 9}

    Paria Sena, Robert; Hadermann, Joke [EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium); Chin, Chun-Mann; Hunter, Emily C. [Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR (United Kingdom); Battle, Peter D., E-mail: peter.battle@chem.ox.ac.uk [Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR (United Kingdom)

    2016-11-15

    A polycrystalline sample of SrLa{sub 2}Ni{sub 2}TeO{sub 9} has been synthesized using a standard ceramic method and characterized by neutron diffraction, magnetometry and electron microscopy. The compound adopts a monoclinic, perovskite-like structure with space group P2{sub 1}/n and unit cell parameters a=5.6008(1), b=5.5872(1), c=7.9018(2) Å, β=90.021(6)° at room temperature. The two crystallographically-distinct B sites are occupied by Ni{sup 2+} and Te{sup 6+} in ratios of 83:17 and 50:50. Both ac and dc magnetometry suggest that the compound is a spin glass below 35 K but the neutron diffraction data show that some regions of the sample are antiferromagnetic. Electron microscopy revealed twinning on a nanoscale and local variations in composition. These defects are thought to be responsible for the presence of two distinct types of antiferromagnetic ordering. - Highlights: • Coexistence of spin-glass and ordered phases. • Local inhomogeneity despite long-range inhomogeneity. • Contrasting magnetic properties of SrLa{sub 2}Ni{sub 2}TeO{sub 9} and La{sub 3}Ni{sub 2}SbO{sub 9}.

  18. Electron tunneling in chemistry

    Zamaraev, K.I.; Khajrutdinov, R.F.; Zhdanov, V.P.; Molin, Yu.N.

    1985-01-01

    Results of experimental and theoretical investigations are outlined systematically on electron tunnelling in chemical reactions. Mechanism of electron transport to great distances is shown to be characteristic to chemical compounds of a wide range. The function of tunnel reactions is discussed for various fields of chemistry, including radiation chemistry, electrochemistry, chemistry of solids, chemistry of surface and catalysis

  19. Sign me up! Determining motivation for high school chemistry students enrolling in a second year chemistry course

    Camarena, Nilda N.

    A sample of 108 Pre-AP Chemistry students in Texas participated in a study to determine motivational factors for enrolling in AP Chemistry and University Chemistry. The factors measured were academic attitude, perceptions of chemistry, confidence level in chemistry, and expectations/experiences in the chemistry class. Students completed two questionnaires, one at the beginning of the year and one at the end. Four high school campuses from two school districts in Texas participated. Two campuses were traditional high schools and two were smaller magnet schools. The results from this study are able to confirm that there are definite correlations between academic attitudes, perceptions, confidence level, and experiences and a student's plans to enroll in AP and University Chemistry. The type of school as well as the student's gender seemed to have an influence on a student's plan to enroll in a second year of chemistry.

  20. Phosphorus forms and chemistry in the soil profile under long-term conservation tillage: a phosphorus-31 nuclear magnetic resonance study.

    Cade-Menun, Barbara J; Carter, Martin R; James, Dean C; Liu, Corey W

    2010-01-01

    In many regions, conservation tillage has replaced conventional tilling practices to reduce soil erosion, improve water conservation, and increase soil organic matter. However, tillage can have marked effects on soil properties, specifically nutrient redistribution or stratification in the soil profile. The objective of this research was to examine soil phosphorus (P) forms and concentrations in a long-term study comparing conservation tillage (direct drilling, "No Till") and conventional tillage (moldboard plowing to 20 cm depth, "Till") established on a fine sandy loam (Orthic Humo-Ferric Podzol) in Prince Edward Island, Canada. No significant differences in total carbon (C), total nitrogen (N), total P, or total organic P concentrations were detected between the tillage systems at any depth in the 0- to 60-cm depth range analyzed. However, analysis with phosphorus-31 nuclear magnetic resonance spectroscopy showed differences in P forms in the plow layer. In particular, the concentration of orthophosphate was significantly higher under No Till than Till at 5 to 10 cm, but the reverse was true at 10 to 20 cm. Mehlich 3-extractable P was also significantly higher in No Till at 5 to 10 cm and significantly higher in Till at 20 to 30 cm. This P stratification appears to be caused by a lack of mixing of applied fertilizer in No Till because the same trends were observed for pH and Mehlich 3-extractable Ca (significantly higher in the Till treatment at 20 to 30 cm), reflecting mixing of applied lime. The P saturation ratio was significantly higher under No Till at 0 to 5 cm and exceeded the recommended limits, suggesting that P stratification under No Till had increased the potential for P loss in runoff from these sites.

  1. The RELixSn2 (RE=La–Nd, Sm, and Gd; 0≤x<1) series revisited. Synthesis, crystal chemistry, and magnetic susceptibilities

    Makongo, Julien P.A.; Suen, Nian-Tzu; Guo, Shengping; Saha, Shanta; Greene, Richard; Paglione, Johnpierre; Bobev, Svilen

    2014-01-01

    This study is concerned with the ternary compounds RELi x Sn 2 (RE=La–Nd, Sm, and Gd; 0≤x 2 phases. These materials crystallize with the base-centered orthorhombic space group Cmcm (No. 63), and can be formally assigned with the CeNiSi 2 structure type (Pearson symbol oC16). Our systematic single-crystal X-ray diffraction studies revealed substantial Li-deficiencies in all cases, with SmSn 2 (space group Cmmm, ZrGa 2 structure type, Pearson symbol oC12) and GdSn 2 (space group Cmcm, ZrSi 2 structure type, Pearson symbol oC12) being completely lithium-free. The structure refinements also uncovered positional disorder on the Sn site neighboring the vacancies. The Sn-disorder and the Li-deficiency correlate, and vary monotonically with the decreased size of the rare-earth atoms in the order RE=La–Nd. The SmSn 2 and GdSn 2 structures are devoid of any disorder. Temperature-dependent studies of the magnetic response of the title compounds are also presented and discussed. -- Graphical abstract: RELi x Sn 2 (RE=La–Nd, 0≤x 2 structure type (a). The Sn-disorder and the Li-deficiency correlate, and vary monotonically with the decreased size of the rare-earth atoms in the order RE=La–Nd. The SmSn 2 (b) and GdSn 2 (c) structures are devoid of any disorder. Highlights: • The crystal structures of the RELi x Sn 2 (RE=La–Nd, 0≤x 2 structure type or defect variant of the CeNiSi 2 structure type. • SmSn 2 is isotypic with the ZrGa 2 structure, while RESn 2 (RE=Gd–Lu) are isotypic with the ZrSi 2 structure

  2. A Wet Chemistry Laboratory Cell

    2008-01-01

    This picture of NASA's Phoenix Mars Lander's Wet Chemistry Laboratory (WCL) cell is labeled with components responsible for mixing Martian soil with water from Earth, adding chemicals and measuring the solution chemistry. WCL is part of the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) instrument suite on board the Phoenix lander. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  3. Conducting Polymers

    would exhibit electronic conductivity, their conductivities (of compressed pellets) were indeed measured by others, and were found to be .... Polyaniline. Polyphenylene. Polypheny lene- vinylene. Table 1. G!NeRAl I ARTICl! structure. Maximum conductivity Stem Stability. Processability. ~. 1.5 x 105. Reacts with Film not n air.

  4. Engineering Faculty Attitudes to General Chemistry Courses in Engineering Curricula

    Garip, Mehmet; Erdil, Erzat; Bilsel, Ayhan

    2006-01-01

    A survey on the attitudes of engineering faculty to chemistry, physics, and mathematics was conducted with the aim of clarifying the attitudes of engineering faculty to chemistry courses in relation to engineering education or curricula and assessing their expectations. The results confirm that on the whole chemistry is perceived as having a…

  5. Green chemistry: A tool in Pharmaceutical Chemistry

    Smita Talaviya; Falguni Majumdar

    2012-01-01

    Green chemistry expresses an area of research developing from scientific discoveries about pollution awareness and it utilizes a set of principles that reduces or eliminates the use or generation of hazardous substances in all steps of particular synthesis or process. Chemists and medicinal scientists can greatly reduce the risk to human health and the environment by following all the valuable principles of green chemistry. The most simple and direct way to apply green chemistry in pharmaceut...

  6. Muons as hyperfine interaction probes in chemistry

    Ghandi, Khashayar, E-mail: kghandi@triumf.ca; MacLean, Amy [Mount Allison University, Department of Chemistry & Biochemistry (Canada)

    2015-04-15

    Spin polarized positive muons injected in matter serve as magnetic probes for the investigation of physical and chemical properties of free radicals, mechanisms of free radical reactions and their formations, and radiation effects. All muon techniques rely on the evolution of spin polarization (of the muon) and in that respect are similar to conventional magnetic resonance techniques. The applications of the muon as a hyperfine probe in several fields in chemistry are described.

  7. Muons as hyperfine interaction probes in chemistry

    Ghandi, Khashayar; MacLean, Amy

    2015-01-01

    Spin polarized positive muons injected in matter serve as magnetic probes for the investigation of physical and chemical properties of free radicals, mechanisms of free radical reactions and their formations, and radiation effects. All muon techniques rely on the evolution of spin polarization (of the muon) and in that respect are similar to conventional magnetic resonance techniques. The applications of the muon as a hyperfine probe in several fields in chemistry are described

  8. From hot atom chemistry to epithermal chemistry

    Roessler, K.

    2004-01-01

    The rise and fall of hot atom chemistry (HAC) over the years from 1934 to 2004 is reviewed. Several applications are discussed, in particular to astrophysics and the interaction of energetic ions and atoms in space. Epithermal chemistry (ETC) is proposed to substitute the old name, since it better fits the energy range as well as the non-thermal and non-equilibrium character of the reactions. ETC also avoids the strong connexion of HAC to nuclear chemistry and stands for the opening of the field to physical chemistry and astrophysics. (orig.)

  9. The latest general chemistry

    Ryu, Geun Bae; Choi, Se Yeong; Kim, Chin Yeong; Yoon, Gil Jung; Lee, Eun Seok; Seo, Moon Gyu

    1995-02-01

    This book deals with the latest general chemistry, which is comprised of twenty-three chapters, the contents of this book are introduction, theory of atoms and molecule, chemical formula and a chemical reaction formula, structure of atoms, nature of atoms and the periodic table, structure of molecule and spectrum, gas, solution, solid, chemical combination, chemical reaction speed, chemical equilibrium, thermal chemistry, oxidation-reduction, electrochemistry, acid-base, complex, aquatic chemistry, air chemistry, nuclear chemistry, metal and nonmetal, organic chemistry and biochemistry. It has exercise in the end of each chapter.

  10. Constitutional dynamic chemistry: bridge from supramolecular chemistry to adaptive chemistry.

    Lehn, Jean-Marie

    2012-01-01

    Supramolecular chemistry aims at implementing highly complex chemical systems from molecular components held together by non-covalent intermolecular forces and effecting molecular recognition, catalysis and transport processes. A further step consists in the investigation of chemical systems undergoing self-organization, i.e. systems capable of spontaneously generating well-defined functional supramolecular architectures by self-assembly from their components, thus behaving as programmed chemical systems. Supramolecular chemistry is intrinsically a dynamic chemistry in view of the lability of the interactions connecting the molecular components of a supramolecular entity and the resulting ability of supramolecular species to exchange their constituents. The same holds for molecular chemistry when the molecular entity contains covalent bonds that may form and break reversibility, so as to allow a continuous change in constitution by reorganization and exchange of building blocks. These features define a Constitutional Dynamic Chemistry (CDC) on both the molecular and supramolecular levels.CDC introduces a paradigm shift with respect to constitutionally static chemistry. The latter relies on design for the generation of a target entity, whereas CDC takes advantage of dynamic diversity to allow variation and selection. The implementation of selection in chemistry introduces a fundamental change in outlook. Whereas self-organization by design strives to achieve full control over the output molecular or supramolecular entity by explicit programming, self-organization with selection operates on dynamic constitutional diversity in response to either internal or external factors to achieve adaptation.The merging of the features: -information and programmability, -dynamics and reversibility, -constitution and structural diversity, points to the emergence of adaptive and evolutive chemistry, towards a chemistry of complex matter.

  11. Improving chemistry performance in CANDU plants

    Turner, C.; Guzonas, D.

    2010-01-01

    There is a strong interplay between coolant chemistry and materials selection in any nuclear power plant system. To achieve the design life of reactor components it is necessary to monitor and control relevant chemistry parameters, such as ionic conductivity, pH, concentrations of dissolved ions and redox species (e.g., hydrogen, hydrazine, oxygen) and the concentrations of suspended corrosion products. Chemistry specifications are set to achieve a balance between the sometimes conflicting requirements to minimize corrosion and radiological dose and to minimize operating and maintenance costs over the lifetime of the plant. For the past decade, Atomic Energy of Canada Limited (AECL) has taken a rigorous and disciplined approach to reviewing and updating all aspects of chemistry control in the CANDU® nuclear power plant (NPP). This approach has included proactively reviewing chemistry operating experience from existing CANDU® and other water-cooled NPPs worldwide to identify and address emerging issues, updating all of our chemistry control documentation to ensure that each chemistry parameter is linked to a specific requirement (e.g., reduce activity transport, monitor for condenser leak) and incorporating the latest results from our Research and Development (R and D) programs to ensure that all chemistry specifications are supported by a sound rationale. The results of this review and update have been incorporated into updated chemistry specifications and, in some cases, modified operating procedures for new and existing plants. In addition, recommendations have been made for design modifications to improve chemistry control in new build plants, especially during periods of shutdown and startup when chemistry control has traditionally been more challenging. Chemistry control in new-build CANDU® plants will rely increasingly on the use of on-line instrumentation interfaced directly to AECL's state-of-the-art chemistry monitoring, diagnostics and analysis

  12. Effect of minimum strength of mirror magnetic field (Bmin) on production of highly charged heavy ions from RIKEN liquid-He-free super conducting electron-cyclotron resonance ion source (RAMSES)

    Arai, Hideyuki; Imanaka, Masashi; Lee, S.-M.Sang-Moo; Higurashi, Yoshihide; Nakagawa, Takahide; Kidera, Masanori; Kageyama, Tadashi; Kase, Masayuki; Yano, Yasushige; Aihara, Toshimitsu

    2002-01-01

    We measured the beam intensity of highly charged heavy ions (O, Ar and Kr ions) as a function of the minimum strength of mirror magnetic field (B min ) of the RIKEN liquid-He-free super conducting electron-cyclotron resonance ion source. In this experiment, we found that the optimum value of B min exists to maximize the beam intensity of highly charged heavy ions and the value was almost the same (∼0.49 T) for various charge state heavy ions

  13. Advanced Chemistry Laboratory

    Federal Laboratory Consortium — Description/History: Chemistry laboratoryThe Advanced Chemistry Laboratory (ACL) is a unique facility designed for working with the most super toxic compounds known...

  14. Electrostatics in Chemistry

    fundamental concepts of electrostatics as applied to atoms and molecules. The electric ... chemistry, the chemistry of the covalent bond, deals with the structures ..... the position of an asteroid named Ceres ... World Scientific. Singapore, 1992.

  15. Preparative radiation chemistry

    Drawe, H.

    1978-01-01

    Preparative synthesis of compounds with the aid of radiation chemistry is increasingly used in laboratories as well as on a technical scale. A large number of new compounds has been produced with the methods of radiation chemistry. With the increasing number of available radiation sources, also the number of synthesis metods in radiation chemistry has increased. This paper can only briefly mention the many possible ways of synthesis in radiation chemistry. (orig./HK) [de

  16. USSR Report Chemistry

    1986-01-01

    THIS REPORT CONTAINS FOREIGN MEDIA INFORMATION FROM THE USSR CONCERNING Adsorption, Alkaloids, ANALYTICAL CHEMISTRY, CATALYSIS, ELECTROCHEMISTRY, Fertilizers, INORGANIC COMPOUNDS, ORGANOPHOSPHOROUS...

  17. Frontiers in Gold Chemistry

    Ahmed A. Mohamed

    2015-01-01

    Basic chemistry of gold tells us that it can bond to sulfur, phosphorous, nitrogen, and oxygen donor ligands. The Frontiers in Gold Chemistry Special Issue covers gold complexes bonded to the different donors and their fascinating applications. This issue covers both basic chemistry studies of gold complexes and their contemporary applications in medicine, materials chemistry, and optical sensors. There is a strong belief that aurophilicity plays a major role in the unending applications of g...

  18. Organic chemistry experiment

    Mun, Seok Sik

    2005-02-01

    This book deals with organic chemistry experiments, it is divided five chapters, which have introduction, the way to write the experiment report and safety in the laboratory, basic experiment technic like recrystallization and extraction, a lot of organic chemistry experiments such as fischer esterification, ester hydrolysis, electrophilic aromatic substitution, aldol reaction, benzoin condensation, wittig reaction grignard reaction, epoxidation reaction and selective reduction. The last chapter introduces chemistry site on the internet and way to find out reference on chemistry.

  19. Heat conduction

    Grigull, U.; Sandner, H.

    1984-01-01

    Included are discussions of rates of heat transfer by conduction, the effects of varying and changing properties, thermal explosions, distributed heat sources, moving heat sources, and non-steady three-dimensional conduction processes. Throughout, the importance of thinking both numerically and symbolically is stressed, as this is essential to the development of the intuitive understanding of numerical values needed for successful designing. Extensive tables of thermophysical properties, including thermal conductivity and diffusivity, are presented. Also included are exact and approximate solutions to many of the problems that arise in practical situations

  20. Analytical chemistry instrumentation

    Laing, W.R.

    1986-01-01

    In nine sections, 48 chapters cover 1) analytical chemistry and the environment 2) environmental radiochemistry 3) automated instrumentation 4) advances in analytical mass spectrometry 5) fourier transform spectroscopy 6) analytical chemistry of plutonium 7) nuclear analytical chemistry 8) chemometrics and 9) nuclear fuel technology

  1. Fundamentals of nuclear chemistry

    Majer, V.

    1982-01-01

    The author of the book has had 25 years of experience at the Nuclear Chemistry of Prague Technical University. In consequence, the book is intended as a basic textbook for students of this field. Its main objectives are an easily understandable presentation of the complex subject and in spite of the uncertainty which still characterizes the definition and subjects of nuclear chemistry - a systematic classification and logical structure. Contents: 1. Introduction (history and definition); 2. General nuclear chemistry (physical fundamentals, hot atom chemistry, interaction of nuclear radiation with matter, radioactive elements, isotope effects, isotope exchange, chemistry of radioactive trace elements); 3. Methods of nuclear chemistry of nuclear chemistry (radiochemical methods, activation, separation and enrichment chemistry); 4. Preparative nuclear chemistry (isotope production, labelled compounds); 5. Analytival nuclear chemistry; 6. Applied nuclear chemistry (isotope applications in general physical and analytical chemistry). The book is supplemented by an annex with tables, a name catalogue and a subject index which will facilitate access to important information. (RB) [de

  2. Friendship chemistry: An examination of underlying factors☆.

    Campbell, Kelly; Holderness, Nicole; Riggs, Matt

    2015-06-01

    Interpersonal chemistry refers to a connection between two individuals that exists upon first meeting. The goal of the current study is to identify beliefs about the underlying components of friendship chemistry. Individuals respond to an online Friendship Chemistry Questionnaire containing items that are derived from interdependence theory and the friendship formation literature. Participants are randomly divided into two subsamples. A principal axis factor analysis with promax rotation is performed on subsample 1 and produces 5 factors: Reciprocal candor, mutual interest, personableness, similarity, and physical attraction. A confirmatory factor analysis is conducted using subsample 2 and provides support for the 5-factor model. Participants with agreeable, open, and conscientious personalities more commonly report experiencing friendship chemistry, as do those who are female, young, and European/white. Responses from participants who have never experienced chemistry are qualitatively analyzed. Limitations and directions for future research are discussed.

  3. Electrical Conductivity.

    Hershey, David R.; Sand, Susan

    1993-01-01

    Explains how electrical conductivity (EC) can be used to measure ion concentration in solutions. Describes instrumentation for the measurement, temperature dependence and EC, and the EC of common substances. (PR)

  4. Conduct Disorder

    ... objections runs away from home often truant from school Children who exhibit these behaviors should receive a comprehensive evaluation by an experience mental health professional. Many children with a conduct disorder may ...

  5. American Association for Clinical Chemistry

    ... Find the answer to your question IN CLINICAL CHEMISTRY Hs-cTnI as a Gatekeeper for Further Cardiac ... Online Harmonization.net Commission on Accreditation in Clinical Chemistry American Board of Clinical Chemistry Clinical Chemistry Trainee ...

  6. Functional Magnetic Nanoparticles

    Gass, James

    Nanoparticle system research and characterization is the focal point of this research and dissertation. In the research presented here, magnetite, cobalt, and ferrite nanoparticle systems have been explored in regard to their magnetocaloric effect (MCE) properties, as well as for use in polymer composites. Both areas of study have potential applications across a wide variety of interdisciplinary fields. Magnetite nanoparticles have been successfully dispersed in a polymer. The surface chemistry of the magnetic nanoparticle proves critical to obtaining a homogenous and well separated high density dispersion in PMMA. Theoretical studies found in the literature have indicated that surface interface energy is a critical component in dispersion. Oleic acid is used to alter the surface of magnetite nanoparticles and successfully achieve good dispersion in a PMMA thin film. Polypyrrole is then coated onto the PMMA composite layer. The bilayer is characterized using cross-sectional TEM, cross-sectional SEM, magnetic characterization, and low frequency conductivity. The results show that the superparmagnetic properties of the as synthesized particles are maintained in the composite. With further study of the properties of these nanoparticles for real and functional uses, MCE is studied on a variety of magnetic nanoparticle systems. Magnetite, manganese zinc ferrite, and cobalt ferrite systems show significant broadening of the MCE and the ability to tune the peak temperature of MCE by varying the size of the nanoparticles. Four distinct systems are studied including cobalt, cobalt core silver shell nanoparticles, nickel ferrite, and ball milled zinc ferrite. The results demonstrate the importance of surface characteristics on MCE. Surface spin disorder appears to have a large influence on the low temperature magnetic and magnetocalorie characteristics of these nanoparticle systems.

  7. Phoenix's Wet Chemistry Laboratory Units

    2008-01-01

    This image shows four Wet Chemistry Laboratory units, part of the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) instrument on board NASA's Phoenix Mars Lander. This image was taken before Phoenix's launch on August 4, 2007. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  8. The New Color of Chemistry: Green Chemistry

    Zuhal GERÇEK

    2012-01-01

    Full Text Available Green chemistry which is the new application of chemistry rules provides solutions to problems that mankind is faced with climate changes, sustainable agriculture, energy, toxics, depletion of natural sources e.g. designing new chemicals and processes that production and utilization of hazardous matters. So, it is the indispensible tool for sustainable development. Current and future chemists should consider the human health and ecological issues in their professional life. In order to provide a solution for this requirement, green chemistry rules and under standings should be primarily taken in the university curriculum and at all educational levels.

  9. Surface chemistry essentials

    Birdi, K S

    2013-01-01

    Surface chemistry plays an important role in everyday life, as the basis for many phenomena as well as technological applications. Common examples range from soap bubbles, foam, and raindrops to cosmetics, paint, adhesives, and pharmaceuticals. Additional areas that rely on surface chemistry include modern nanotechnology, medical diagnostics, and drug delivery. There is extensive literature on this subject, but most chemistry books only devote one or two chapters to it. Surface Chemistry Essentials fills a need for a reference that brings together the fundamental aspects of surface chemistry w

  10. Fundamentals of reactor chemistry

    Akatsu, Eiko

    1981-12-01

    In the Nuclear Engineering School of JAERI, many courses are presented for the people working in and around the nuclear reactors. The curricula of the courses contain also the subject material of chemistry. With reference to the foreign curricula, a plan of educational subject material of chemistry in the Nuclear Engineering School of JAERI was considered, and the fundamental part of reactor chemistry was reviewed in this report. Since the students of the Nuclear Engineering School are not chemists, the knowledge necessary in and around the nuclear reactors was emphasized in order to familiarize the students with the reactor chemistry. The teaching experience of the fundamentals of reactor chemistry is also given. (author)

  11. A simple route to synthesize conductive stimuli-responsive polypyrrole nanocomposite hydrogel particles with strong magnetic properties and their performance for removal of hexavalent chromium ions from aqueous solution

    Ahmad, Hasan, E-mail: samarhass@yahoo.com [Department of Chemistry, Rajshahi University, Rajshahi 6205 (Bangladesh); Rahman, Mohammad Mostafizar; Ali, Mohammad Azgar [Department of Chemistry, Rajshahi University, Rajshahi 6205 (Bangladesh); Minami, Hideto [Graduate School of Engineering, Kobe University, Kobe 657-8501 (Japan); Tauer, Klaus [Max Planck Institute of Colloid and Interfaces, Am Mühlenberg, 14476 Golm (Germany); Gafur, Mohammad Abdul [Pilot Plant and Process Development Centre, BCSIR, Dhaka 1205 (Bangladesh); Rahman, Mohammad Mahbubor [Department of Chemistry, Rajshahi University, Rajshahi 6205 (Bangladesh)

    2016-08-15

    A combination of maghemite polypyrrole (PPy/γ-Fe{sub 2}O{sub 3}) and stimuli-responsive properties in the same hydrogel microspheres is expected to enhance their application potential in various fields such as tissue engineering, regenerative medicine, biosensors, biomedical applications and removal of heavy metals from waste water, catalysis etc. In this investigation a simple two step process is used to prepare conductive stimuli-responsive polypyrrole (PPy) composite hydrogel particles with strong magnetic properties. Poly(styrene-methacrylic acid-N-isopropylacrylamide-polyethelene glycol methacrylate) or P(S-NIPAM-MAA-PEGMA) hydrogel seed particles are first prepared by soap-free precipitation copolymerization. The copolymer hydrogel particles exhibited both temperature- and pH-responsive volume phase transition. Conductive P(S-NIPAM-MAA-PEGMA)/PPy/γ-Fe{sub 2}O{sub 3} nanocomposite hydrogel particles are then prepared by seeded chemical oxidative polymerization of pyrrole in the presence of P(S-NIPAM-MAA-PEGMA) hydrogel seed particles using FeCl{sub 3} as a oxidant and p-toluene sulfonic acid ( p-TSA) as a dopant. In the reaction system FeCl{sub 3} functioned as a source of Fe(III) for the formation of γ-Fe{sub 2}O{sub 3}. This reaction also requires the initial presence of Fe(II) provided by the addition of FeCl{sub 2}. The size and size distribution, surface structure, and morphology of the prepared conductive composite hydrogel particles are confirmed by FTIR, electron micrographs, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and UV–visible spectroscopy. The performance of nanocomposite hydrogel particles has been evaluated for the removal of hexavalent chromium (Cr) ions from water. - Highlights: • P(S-NIPAM-MAA-PEGMA) hydrogel particles were prepared. • P(S-NIPAM-MAA-PEGMA)/PPy/γ-Fe{sub 2}O{sub 3} nanocomposite hydrogel particles were prepared. • Oxidative polymerization of pyrrole and precipitation of γ-Fe{sub 2}O{sub 3

  12. Annual report 1985 Chemistry Department

    Funck, J.; Larsen, E.; Nielsen, O.J.

    1986-03-01

    This report contains a brief survey of the main activities in the Chemistry Department. All particles and reports published and lectures given in 1985 are presented. The facilities and equipment are mentioned briefly. The activities are divided into the following groups: radioisotope chemistry, analytical- and organic chemistry, environmental chemistry, polymer chemistry, geochemistry and waste disposal, radical chemistry, positron annihilation, mineral processing, and general. (author)

  13. Annual report 1984 Chemistry Department

    Funck, J.; Larsen, E.; Nielsen, O.J.

    1985-03-01

    This report contains a brief survey of the main activities in the Chemistry Department. All articles and reports published and lectures given in 1984 are presented. The facilities and equipment are mentioned briefly. The activities are divided into the following groups: radioisotope chemistry, analytical- and organic chemistry , environmental chemistry, polymer chemistry, geochemistry and waste disposal, radical chemistry, positron annihilation, mineral processing, and general. (author)

  14. Fundamentals of nuclear chemistry

    Matel, L.; Dulanska, S.

    2013-01-01

    This text-book is an introductory text in nuclear chemistry and radiochemistry, aimed on university undergraduate students in chemistry and related disciplines (physics, nuclear engineering). It covers the key aspects of modern nuclear chemistry. The text begins with basic theories in contemporary physics. It relates nuclear phenomena to key divisions of chemistry such as atomic structure, spectroscopy, equilibria and kinetics. It also gives an introduction to sources of ionizing radiation, detection of ionizing radiation, nuclear power industry and accident on nuclear installations as well as basic knowledge's of radiobiology. This book is essential reading for those taking a first course in nuclear chemistry and is a useful companion to other volumes in physical and analytical chemistry. It will also be of use to those new to working in nuclear chemistry or radiochemistry.

  15. Current developments in radiation chemistry

    Cooper, R.

    2000-01-01

    Full text: The theme of the 2000 Gordon Conference on Radiation Chemistry was 'diversity'. The range of topics covered was heralded by the opening presentations which went from the galactic to molecular biology, radiation chemistry and non thermal surface processes in the outer solar system to achievements and open challenges in DNA research. The rest of the conference reflected the extended usage of radiation chemistry -its processes and techniques - applied to a panorama of topics. The ability to generate either oxidising or reducing free radicals in known quantities has been the foundation stone on which all applications are based. In particular it is noticeable that biological systems have been attempted by an increasing number of workers, such as studies of biological ageing and also reactions of nitric oxide in biological environments. Electron transfer processes in proteins are straightforward applications of solvated electron chemistry even if the results are not straightforward in their interpretation. Other topics presented include, radiation chemical processes induced in: supercritical CO 2 , treatment of contaminated materials, 3-dimensional Fullerenes, zeolites and radiation catalysis. In material science, aspects of ions and excited states in polymers, conducting polymers, donor acceptor processes in photo curing, enhancement of photo-electron yields in doped silver halides- improvement of the photographic process, radiation chemistry in cages and bubbles are discussed. The fundamental aspects of radiation chemistry are not yet all worked out. Subpicosecond pulsed electron beam sources, some of them 'tabletop', are still being planned to probe the early events in radiation chemistry both in water and in organic solvents. There is still an interest in the chemistry produced by pre-solvated electrons and the processes induced by heavy ion radiolysis. The description of the relaxation of an irradiated system which contains uneven distributions of ions

  16. The Hitchhiker's Guide to Flow Chemistry ∥.

    Plutschack, Matthew B; Pieber, Bartholomäus; Gilmore, Kerry; Seeberger, Peter H

    2017-09-27

    Flow chemistry involves the use of channels or tubing to conduct a reaction in a continuous stream rather than in a flask. Flow equipment provides chemists with unique control over reaction parameters enhancing reactivity or in some cases enabling new reactions. This relatively young technology has received a remarkable amount of attention in the past decade with many reports on what can be done in flow. Until recently, however, the question, "Should we do this in flow?" has merely been an afterthought. This review introduces readers to the basic principles and fundamentals of flow chemistry and critically discusses recent flow chemistry accounts.

  17. Conduct disorders

    Buitelaar, J.K.; Smeets, K.C.; Herpers, P.; Scheepers, F.; Glennon, J.; Rommelse, N.N.J.

    2013-01-01

    Conduct disorder (CD) is a frequently occurring psychiatric disorder characterized by a persistent pattern of aggressive and non-aggressive rule breaking antisocial behaviours that lead to considerable burden for the patients themselves, their family and society. This review paper updates diagnostic

  18. Nuclear chemistry in the traditional chemistry program

    Kleppinger, E.W.

    1993-01-01

    The traditional undergraduate program for chemistry majors, especially at institutions devoted solely to undergraduate education, has limited space for 'special topics' courses in areas such as nuclear and radiochemistry. A scheme is proposed whereby the basic topics covered in an introductury radiochemistry course are touched upon, and in some cases covered in detail, at some time during the four-year sequence of courses taken by a chemistry major. (author) 6 refs.; 7 tabs

  19. The New Color of Chemistry: Green Chemistry

    Zuhal GERÇEK

    2012-01-01

    Green chemistry which is the new application of chemistry rules provides solutions to problems that mankind is faced with climate changes, sustainable agriculture, energy, toxics, depletion of natural sources e.g. designing new chemicals and processes that production and utilization of hazardous matters. So, it is the indispensible tool for sustainable development. Current and future chemists should consider the human health and ecological issues in their professional life. In order to provid...

  20. Mendeleev-2013. VII All-Russian conference of young scientists, postgraduate students and students with international participation on chemistry and nanomaterials. Book of abstracts. Section 2. Analytic chemistry

    2013-01-01

    VII All-Russian conference of young scientists, postgraduate students and students with international participation on chemistry and nanomaterials was conducted on the Chemistry department of Saint-Petersburg University on April, 2-5, 2013. In the conference participants from 14 countries took part. There were five sections: Nanochemistry and nanomaterials, Analytic chemistry, Inorganic chemistry, Organic chemistry, Physical chemistry. In the collection (Section 2 - Analytic chemistry) there are the abstracts concerning determination of heavy metals in environmental samples, petroleum products, different biological active and toxic substances in human tissues, food products and water; usage of nanoparticles for modification of electrodes for electrochemical methods of analysis, etc [ru

  1. Mars aqueous chemistry experiment

    Clark, Benton C.; Mason, Larry W.

    1994-06-01

    Mars Aqueous Chemistry Experiment (MACE) is designed to conduct a variety of measurements on regolith samples, encompassing mineral phase analyses, chemical interactions with H2O, and physical properties determinations. From these data, much can be learned or inferred regarding the past weathering environment, the contemporaneous soil micro-environments, and the general chemical and physical state of the Martian regolith. By analyzing both soil and duricrust samples, the nature of the latter may become more apparent. Sites may be characterized for comparative purposes and criteria could be set for selection of high priority materials on future sample return missions. The second year of the MACE project has shown significant progress in two major areas. MACE Instrument concept definition is a baseline design that has been generated for the complete MACE instrument, including definition of analysis modes, mass estimates and thermal model. The design includes multiple reagent reservoirs, 10 discrete analysis cells, sample manipulation capability, and thermal control. The MACE Measurement subsystems development progress is reported regarding measurement capabilities for aqueous ion sensing, evolved gas sensing, solution conductivity measurement, reagent addition (titration) capabilities, and optical sensing of suspended particles.

  2. Mars aqueous chemistry experiment

    Clark, Benton C.; Mason, Larry W.

    1994-01-01

    Mars Aqueous Chemistry Experiment (MACE) is designed to conduct a variety of measurements on regolith samples, encompassing mineral phase analyses, chemical interactions with H2O, and physical properties determinations. From these data, much can be learned or inferred regarding the past weathering environment, the contemporaneous soil micro-environments, and the general chemical and physical state of the Martian regolith. By analyzing both soil and duricrust samples, the nature of the latter may become more apparent. Sites may be characterized for comparative purposes and criteria could be set for selection of high priority materials on future sample return missions. The second year of the MACE project has shown significant progress in two major areas. MACE Instrument concept definition is a baseline design that has been generated for the complete MACE instrument, including definition of analysis modes, mass estimates and thermal model. The design includes multiple reagent reservoirs, 10 discrete analysis cells, sample manipulation capability, and thermal control. The MACE Measurement subsystems development progress is reported regarding measurement capabilities for aqueous ion sensing, evolved gas sensing, solution conductivity measurement, reagent addition (titration) capabilities, and optical sensing of suspended particles.

  3. Antiparallel Dynamic Covalent Chemistries.

    Matysiak, Bartosz M; Nowak, Piotr; Cvrtila, Ivica; Pappas, Charalampos G; Liu, Bin; Komáromy, Dávid; Otto, Sijbren

    2017-05-17

    The ability to design reaction networks with high, but addressable complexity is a necessary prerequisite to make advanced functional chemical systems. Dynamic combinatorial chemistry has proven to be a useful tool in achieving complexity, however with some limitations in controlling it. Herein we introduce the concept of antiparallel chemistries, in which the same functional group can be channeled into one of two reversible chemistries depending on a controllable parameter. Such systems allow both for achieving complexity, by combinatorial chemistry, and addressing it, by switching from one chemistry to another by controlling an external parameter. In our design the two antiparallel chemistries are thiol-disulfide exchange and thio-Michael addition, sharing the thiol as the common building block. By means of oxidation and reduction the system can be reversibly switched from predominantly thio-Michael chemistry to predominantly disulfide chemistry, as well as to any intermediate state. Both chemistries operate in water, at room temperature, and at mildly basic pH, which makes them a suitable platform for further development of systems chemistry.

  4. Proceedings of the DAE-BRNS fifth interdisciplinary symposium on materials chemistry

    Jafar, Mohsin; Tyagi, Adish; Tyagi, Deepak

    2014-12-01

    The focus of the present symposium on materials chemistry was on research areas in materials chemistry like: nuclear materials; high purity materials; nanomaterials and clusters; carbon based materials; fuel cell materials and other electro-ceramics; biomaterials; polymers and soft condensed matter; materials for energy conversion; thin films and surface chemistry; magnetic materials; catalysis; chemical sensors; organic and organometallic compounds; computational material chemistry etc. Papers relevant to INIS are indexed separately

  5. Conductivity Probe

    2008-01-01

    The Thermal and Electrical Conductivity Probe (TECP) for NASA's Phoenix Mars Lander took measurements in Martian soil and in the air. The needles on the end of the instrument were inserted into the Martian soil, allowing TECP to measure the propagation of both thermal and electrical energy. TECP also measured the humidity in the surrounding air. The needles on the probe are 15 millimeters (0.6 inch) long. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  6. Atmospheric chemistry and climate

    Satheesh, SK

    2012-01-01

    Atmospheric chemistry is a branch of atmospheric science where major focus is the composition of the Earth's atmosphere. Knowledge of atmospheric composition is essential due to its interaction with (solar and terrestrial) radiation and interactions of atmospheric species (gaseous and particulate matter) with living organisms. Since atmospheric chemistry covers a vast range of topics, in this article the focus is on the chemistry of atmospheric aerosols with special emphasis on the Indian reg...

  7. Polymer chemistry (revised edition)

    Kim, Jae Mum

    1987-02-01

    This book deals with polymer chemistry, which is divided into fourteen chapters. The contents of this book are development of polymer chemistry, conception of polymer, measurement of polymer chemistry, conception of polymer, measurement of polymer, molecule structure of polymer, thermal prosperities of solid polymer, basic theory of polymerization, radical polymerization, ion polymerization, radical polymerization, copolymerization, polymerization by step-reaction, polymer reaction, crown polymer and inorganic polymer on classification and process of creation such as polymeric sulfur and carbon fiber.

  8. Chemistry of the elements

    Greenwood, N.N.; Earnshaw, A.

    1984-01-01

    This textbook presents an account of the chemistry of the elements for both undergraduate and postgraduate students. It covers not only the 'inorganic' chemistry of the elements, but also analytical, theoretical, industrial, organometallic;, bio-inorganic and other areas of chemistry which apply. The following elements of special nuclear interest are included: Rb, Cs, Fr, Sr, Ba, Ra, Po, At, Rn, Sc, Y, Zr, Hf, V, Nb, Ta, Mo, Tc, Ru, the Lanthanide Elements, the Actinide Elements. (U.K.)

  9. Using a Web Application to Conduct and Investigate Syntheses of Methyl Orange Remotely

    van Rens, Lisette; van Dijk, Hans; Mulder, Jan; Nieuwland, Pieter

    2013-01-01

    Thirty-six pre-university chemistry students and two chemistry teachers used flow chemistry as a technology for the synthesis of methyl orange. FutureChemistry and VU University Amsterdam cooperatively created FlowStart Remote, a device that enabled the students to remotely conduct this synthesis and in real time monitor and control the device via…

  10. Using a Web Application to Conduct and Investigate Syntheses of Methyl Orange Remotely

    van Rens, L.; van Dijk, H.; Mulder, J.; Nieuwland, P

    2013-01-01

    Thirty-six pre-university chemistry students and two chemistry teachers used flow chemistry as a technology for the synthesis of methyl orange. FutureChemistry and VU University Amsterdam cooperatively created FlowStart Remote, a device that enabled the students to remotely conduct this synthesis

  11. Evaluating the efficacy of a chemistry video game

    Shapiro, Marina

    A quasi-experimental design pre-test/post-test intervention study utilizing a within group analysis was conducted with 45 undergraduate college chemistry students that investigated the effect of implementing a game-based learning environment into an undergraduate college chemistry course in order to learn if serious educational games (SEGs) can be used to achieve knowledge gains of complex chemistry concepts and to achieve increase in students' positive attitude toward chemistry. To evaluate if students learn chemistry concepts by participating in a chemistry game-based learning environment, a one-way repeated measures analysis of variance (ANOVA) was conducted across three time points (pre-test, post-test, delayed post-test which were chemistry content exams). Results showed that there was an increase in exam scores over time. The results of the ANOVA indicated a statistically significant time effect. To evaluate if students' attitude towards chemistry increased as a result of participating in a chemistry game-based learning environment a paired samples t-test was conducted using a chemistry attitudinal survey by Mahdi (2014) as the pre- and post-test. Results of the paired-samples t-test indicated that there was no significant difference in pre-attitudinal scores and post-attitudinal scores.

  12. From trace chemistry to single atom chemistry

    Adloff, J.P.

    1993-01-01

    Hot atom chemistry in the vast majority of experimental works deals with the trace amount of radioactive matters. Accordingly, the concept of trace chemistry is at the heart of hot atom chemistry. Some aspects of the chemistry at trace scale and at subtrace scale are presented together with the related problems of speciation and the complication which may arise due to the formation of radio colloids. The examples of 127 I(n,γ) 128 I and 132 Te (β - ) 132 I are shown, and the method based on radioactivity was used. The procedure of separating the elements in pitchblende is shown as the example of the chemistry of traces. 13 27 Al+ 2 4 He→ 0 1 n+ 15 30 P and 15 30 P→ 14 30 Si+e + +V are shown, and how to recognize the presence of radioactive colloids is explained. The formation of radiocolloids is by the sorption of a trace radioelement on pre-existing colloidal impurity or the self-condensation of monomeric species. The temporal parameters of the nature of reactions at trace concentration are listed. The examples of Class A and Class B reactions are shown. The kinetics of reactions at trace level, radon concentration, anthropogenic Pu and natural Pu in environment, the behavior of Pu atoms and so on are described. (K.I.)

  13. Advances in quantum chemistry

    Sabin, John R

    2013-01-01

    Advances in Quantum Chemistry presents surveys of current topics in this rapidly developing field that has emerged at the cross section of the historically established areas of mathematics, physics, chemistry, and biology. It features detailed reviews written by leading international researchers. This volume focuses on the theory of heavy ion physics in medicine.Advances in Quantum Chemistry presents surveys of current topics in this rapidly developing field that has emerged at the cross section of the historically established areas of mathematics, physics, chemistry, and biology. It features

  14. Canopy Chemistry (OTTER)

    National Aeronautics and Space Administration — ABSTRACT: Canopy characteristics: leaf chemistry, specific leaf area, LAI, PAR, IPAR, NPP, standing biomass--see also: Meteorology (OTTER) for associated...

  15. USSR Report, Chemistry

    1986-01-01

    This USSR Report on Chemistry contains articles on Aerosols, Adsorption, Biochemistry, Catalysis, Chemical Industry, Coal Gasification, Electrochemistry, Explosives and Explosions, Fertilizers, Food...

  16. Elements of environmental chemistry

    Hites, R. A; Raff, Jonathan D

    2012-01-01

    ... more. Extensively revised, updated, and expanded, this second edition includes new chapters on atmospheric chemistry, climate change, and polychlorinated biphenyls and dioxins, and brominated flame retardants...

  17. Green Chemistry Pedagogy

    Kolopajlo, Larry

    2017-02-01

    This chapter attempts to show how the practice of chemistry teaching and learning is enriched by the incorporation of green chemistry (GC) into lectures and labs. To support this viewpoint, evidence from a wide range of published papers serve as a cogent argument that GC attracts and engages both science and nonscience students, enhances chemistry content knowledge, and improves the image of the field, while preparing the world for a sustainable future. Published pedagogy associated with green and sustainable chemistry is critically reviewed and discussed.

  18. DOE fundamentals handbook: Chemistry

    1993-01-01

    This handbook was developed to assist nuclear facility operating contractors in providing operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of chemistry. This volume contains the following modules: reactor water chemistry (effects of radiation on water chemistry, chemistry parameters), principles of water treatment (purpose; treatment processes [ion exchange]; dissolved gases, suspended solids, and pH control; water purity), and hazards of chemicals and gases (corrosives [acids, alkalies], toxic compounds, compressed gases, flammable/combustible liquids)

  19. Measurement of thermal conductance

    Kuchnir, M.

    1977-01-01

    The 6-m long, 45-kG, warm-iron superconducting magnets envisioned for the Energy Doubler stage of the Fermilab accelerator require stiff supports with minimized thermal conductances in order to keep the refrigeration power reasonable. The large number of supports involved in the system required a careful study of their heat conduction from the room temperature wall to the intercepting refrigeration at 20 0 K and to the liquid helium. For this purpose the thermal conductance of this support was measured by comparing it with the thermal conductance of a copper strap of known geometry. An association of steady-state thermal analysis and experimental thermal conductivity techniques forms the basis of this method. An important advantage is the automatic simulation of the 20 0 K refrigeration intercept by the copper strap, which simplifies the apparatus considerably. This relative resistance technique, which uses electrical analogy as a guideline, is applicable with no restrictions for materials with temperature-independent thermal conductivity. For other materials the results obtained are functions of the specific temperature interval involved in the measurements. A comprehensive review of the literature on thermal conductivity indicates that this approach has not been used before. A demonstration of its self-consistency is stressed here rather than results obtained for different supports

  20. Green chemistry: to rethink chemistry for tomorrow's world. Press briefing of 20 January 2015

    Legrand, Francois

    2015-01-01

    This document discusses various issues related to the development of the green chemistry sector, and mentions and presents activities performed by the CEA in this respect. A first part outlines how green chemistry is an answer to stakes for a sustainable development. The second part addresses metal recycling: recovery of silver from photovoltaic cells, avoiding tensions related to rare earth supply. The third part discusses how to replace dangerous or costly compounds (chromium in aircraft paintings, platinum in fuel cells, ruthenium in photovoltaic cells, rare earth in magnetic wire). The fourth part addresses how to transform wastes into useful products (production of formamides, of aromatic compounds, and of methanol, respectively from waste recycling, natural lignin, and CO_2). The fifth part presents new concepts for chemical synthesis: chemistry under ultrasounds, production of hydrogen from water. The sixth part presents contributions of life sciences to green chemistry: reduction of carbon dioxide emissions, bioremediation (biology for soil rehabilitation), production of molecules of interest by using micro algae, enzymes or bacteria. The last part discusses issues which outline that chemistry is at the heart of challenges for a sustainable nuclear in terms of materials, for a closed fuel cycle, in terms of fuel cycle processes, of installation sanitation and dismantling. Appendices formulate 5 societal challenges for green chemistry, and 12 background principles of green chemistry

  1. Slow magnetic relaxation in a cobalt magnetic chain.

    Yang, Chen-I; Chuang, Po-Hsiang; Lu, Kuang-Lieh

    2011-04-21

    A homospin ladder-like chain, [Co(Hdhq)(OAc)](n) (1; H(2)dhq = 2,3-dihydroxyquinoxaline), shows a single-chain-magnet-like (SCM-like) behavior with the characteristics of frequency dependence of the out-of-phase component in alternating current (ac) magnetic susceptibilities and hysteresis loops. © The Royal Society of Chemistry 2011

  2. Magnetic Damping For Maglev

    S. Zhu

    1998-01-01

    Full Text Available Magnetic damping is one of the important parameters that control the response and stability of maglev systems. An experimental study to measure magnetic damping directly is presented. A plate attached to a permanent magnet levitated on a rotating drum was tested to investigate the effect of various parameters, such as conductivity, gap, excitation frequency, and oscillation amplitude, on magnetic damping. The experimental technique is capable of measuring all of the magnetic damping coefficients, some of which cannot be measured indirectly.

  3. Quantized Majorana conductance

    Zhang, Hao; Liu, Chun-Xiao; Gazibegovic, Sasa; Xu, Di; Logan, John A.; Wang, Guanzhong; van Loo, Nick; Bommer, Jouri D. S.; de Moor, Michiel W. A.; Car, Diana; Op Het Veld, Roy L. M.; van Veldhoven, Petrus J.; Koelling, Sebastian; Verheijen, Marcel A.; Pendharkar, Mihir; Pennachio, Daniel J.; Shojaei, Borzoyeh; Lee, Joon Sue; Palmstrøm, Chris J.; Bakkers, Erik P. A. M.; Sarma, S. Das; Kouwenhoven, Leo P.

    2018-04-01

    Majorana zero-modes—a type of localized quasiparticle—hold great promise for topological quantum computing. Tunnelling spectroscopy in electrical transport is the primary tool for identifying the presence of Majorana zero-modes, for instance as a zero-bias peak in differential conductance. The height of the Majorana zero-bias peak is predicted to be quantized at the universal conductance value of 2e2/h at zero temperature (where e is the charge of an electron and h is the Planck constant), as a direct consequence of the famous Majorana symmetry in which a particle is its own antiparticle. The Majorana symmetry protects the quantization against disorder, interactions and variations in the tunnel coupling. Previous experiments, however, have mostly shown zero-bias peaks much smaller than 2e2/h, with a recent observation of a peak height close to 2e2/h. Here we report a quantized conductance plateau at 2e2/h in the zero-bias conductance measured in indium antimonide semiconductor nanowires covered with an aluminium superconducting shell. The height of our zero-bias peak remains constant despite changing parameters such as the magnetic field and tunnel coupling, indicating that it is a quantized conductance plateau. We distinguish this quantized Majorana peak from possible non-Majorana origins by investigating its robustness to electric and magnetic fields as well as its temperature dependence. The observation of a quantized conductance plateau strongly supports the existence of Majorana zero-modes in the system, consequently paving the way for future braiding experiments that could lead to topological quantum computing.

  4. Annual report 1989 Chemistry Department

    Funck, J.; Neve Larsen, Aa.; Larsen, E.; Nielsen, O.J.

    1990-03-01

    This report contains a brief survey of the main activities in the Chemistry Department. The names and abstracts of all articles and reports published and lectures given in 1989 are presented. The facilities and equipment are mentioned briefly. The activities are divided into the following groups: radioisotope chemistry, analytical- and organic chemistry, environmental chemistry, polymer chemistry, chemical reactivity, mineral processing, and general. (author)

  5. Annual report 1988 Chemistry Department

    Funck, J.; Neve Larsen, Aa.; Larsen, E.; Nielsen, O.J.

    1989-05-01

    This report contains a brief survey of the main activities in the Chemistry Department. The names and abstracts of all articles and reports published and lectures given in 1988 are presented. The facilities and equipment are mentioned briefly. The activities are divided into the following groups: radioisotope chemistry, analytical- and organic chemistry, environmental chemistry, polymer chemistry, chemical reactivity, mineral processing, and general. (author)

  6. Annual report 1986 chemistry department

    Funck, J.; Larsen, E.; Nielsen, O.J.

    1987-03-01

    This report contains a brief survey of the main activities in the Chemistry Department. All articles and reports published and lectures given in 1986 are presented. The facilities and equipment are mentioned briefly. The activities are divided into the following groups: radioisotope chemistry, analytical- and organic chemistry, environmental chemistry, polymer chemistry, radical chemistral, mineral processing, and general. (author)

  7. Undergraduate students' goals for chemistry laboratory coursework

    DeKorver, Brittland K.

    Chemistry laboratory coursework has the potential to offer many benefits to students, yet few of these learning goals are realized in practice. Therefore, this study seeks to characterize undergraduate students' learning goals for their chemistry laboratory coursework. Data were collected by recording video of students completing laboratory experiments and conducting interviews with the students about their experiences that were analyzed utilizing the frameworks of Human Constructivism and Self-Regulated Learning. A cross-sectional sampling of students allowed comparisons to be made among students with varying levels of chemistry experience and interest in chemistry. The student goals identified by this study were compared to previously described laboratory learning goals of the faculty who instruct these courses in an effort to identify potential avenues to improve laboratory learning.

  8. Single-molecule magnet engineering

    Pedersen, Kasper Steen; Bendix, Jesper; Clérac, Rodolphe

    2014-01-01

    Tailoring the specific magnetic properties of any material relies on the topological control of the constituent metal ion building blocks. Although this general approach does not seem to be easily applied to traditional inorganic bulk magnets, coordination chemistry offers a unique tool to delica...

  9. Conducting, magnetic polyaniline/Ba{sub 0.25}Sr{sub 0.75} Fe{sub 11}(Ni{sub 0.5}Mn{sub 0.5})O{sub 19} nanocomposite: Fabrication, characterization and application

    Ezzati, S. Noushin, E-mail: sn.ezzati@iau-saveh.ac.ir [Young Researchers and Elite Club, Saveh Branch, Islamic Azad University, Saveh (Iran, Islamic Republic of); Rabbani, Mahboubeh [Department of Chemistry, Iran University of Science and Technology, Narmak, Tehran 16846-13114 (Iran, Islamic Republic of); Leblanc, Roger M. [Department of Chemistry, University of Miami, Coral Gables, FL 33124 (United States); Asadi, Ebadullah, E-mail: ebadasadi@gmail.com [Department of Chemistry, University of Miami, Coral Gables, FL 33124 (United States); Department of Chemistry, Amirkabir University of Technology, P. O. Box: 15875-4413, Tehran (Iran, Islamic Republic of); Ezzati, S. Mohammad H. [Young Researchers and Elite Club, Saveh Branch, Islamic Azad University, Saveh (Iran, Islamic Republic of); Rahimi, Rahmatollah [Department of Chemistry, Iran University of Science and Technology, Narmak, Tehran 16846-13114 (Iran, Islamic Republic of); Azodi-Deilami, Saman [Young Researchers and Elite Club, South Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2015-10-15

    In this contribution, Ni/Mn doped Barium Strontium Ferrite nanoparticles (Ba{sub 0.25}Sr{sub 0.75}Fe{sub 11}(Ni{sub 0.5}Mn{sub 0.5})O{sub 19}) and conducting polyaniline/Ba{sub 0.25}Sr{sub 0.75}Fe{sub 11}(Ni{sub 0.5}Mn{sub 0.5})O{sub 19} nanocomposite were fabricated successfully through sol–gel method and in-situ polymerization technique, respectively. Field emission scanning electron microscope (FESEM), Energy-dispersive X-ray spectroscopy analysis (EDX), X-ray powder diffraction (XRD), Mössbauer spectroscopic measurements and Fourier transform infrared spectroscope (FT-IR) analyses were adopted to confirm the composition, morphology and structure of materials. The obtained results revealed the formation of hexagonal M-type rod-shape ferrite with average particle size of about 45 nm (according to XRD data, using Debye–Scherre formula). The saturation magnetization of ferrite nanoparticles and PANI/Ferrite nanocomposite reported 44.03 and 9.85 emu/g, respectively, using vibrant sample magnetometer (VSM). Standard four-point-probe technique was employed to measure the conductivity of samples. Also optical characteristic of samples was examined by means of UV–Vis and Diffuse Reflectance Spectra (DRS) techniques which proved the formation of conducting coating of emeraldine on the surface of magnetic nanoparticles. Also the UV–vis studies indicated that the ferrite nanoparticles have an optical band gap of 1.8 eV while the values of 1.65 and 2.66 eV obtained for PANI/Ferrite nanocomposite. Finally, the microwave absorption properties of prepared nanoferrite and nanocomposite at different thicknesses (2, 3 and 4 mm) were determined at the X-band (8–12 GHz) using vector network analyzer (VNA). In this study, minimum reflection loss of −21.68 dB and maximum available bandwidth of 4.8 GHz were obtained for PANI/Ferrite (20 wt% ferrite) at the frequency of 10.6 GHz. The results suggested the fabricated nanocomposite could be a suitable candidate for

  10. Conducting, magnetic polyaniline/Ba0.25Sr0.75 Fe11(Ni0.5Mn0.5)O19 nanocomposite: Fabrication, characterization and application

    Ezzati, S. Noushin; Rabbani, Mahboubeh; Leblanc, Roger M.; Asadi, Ebadullah; Ezzati, S. Mohammad H.; Rahimi, Rahmatollah; Azodi-Deilami, Saman

    2015-01-01

    In this contribution, Ni/Mn doped Barium Strontium Ferrite nanoparticles (Ba 0.25 Sr 0.75 Fe 11 (Ni 0.5 Mn 0.5 )O 19 ) and conducting polyaniline/Ba 0.25 Sr 0.75 Fe 11 (Ni 0.5 Mn 0.5 )O 19 nanocomposite were fabricated successfully through sol–gel method and in-situ polymerization technique, respectively. Field emission scanning electron microscope (FESEM), Energy-dispersive X-ray spectroscopy analysis (EDX), X-ray powder diffraction (XRD), Mössbauer spectroscopic measurements and Fourier transform infrared spectroscope (FT-IR) analyses were adopted to confirm the composition, morphology and structure of materials. The obtained results revealed the formation of hexagonal M-type rod-shape ferrite with average particle size of about 45 nm (according to XRD data, using Debye–Scherre formula). The saturation magnetization of ferrite nanoparticles and PANI/Ferrite nanocomposite reported 44.03 and 9.85 emu/g, respectively, using vibrant sample magnetometer (VSM). Standard four-point-probe technique was employed to measure the conductivity of samples. Also optical characteristic of samples was examined by means of UV–Vis and Diffuse Reflectance Spectra (DRS) techniques which proved the formation of conducting coating of emeraldine on the surface of magnetic nanoparticles. Also the UV–vis studies indicated that the ferrite nanoparticles have an optical band gap of 1.8 eV while the values of 1.65 and 2.66 eV obtained for PANI/Ferrite nanocomposite. Finally, the microwave absorption properties of prepared nanoferrite and nanocomposite at different thicknesses (2, 3 and 4 mm) were determined at the X-band (8–12 GHz) using vector network analyzer (VNA). In this study, minimum reflection loss of −21.68 dB and maximum available bandwidth of 4.8 GHz were obtained for PANI/Ferrite (20 wt% ferrite) at the frequency of 10.6 GHz. The results suggested the fabricated nanocomposite could be a suitable candidate for decreasing radar signature. - Highlights: • Polyaniline

  11. Conduct disorders.

    Buitelaar, Jan K; Smeets, Kirsten C; Herpers, Pierre; Scheepers, Floor; Glennon, Jeffrey; Rommelse, Nanda N J

    2013-02-01

    Conduct disorder (CD) is a frequently occurring psychiatric disorder characterized by a persistent pattern of aggressive and non-aggressive rule breaking antisocial behaviours that lead to considerable burden for the patients themselves, their family and society. This review paper updates diagnostic and therapeutic approaches to CD in the light of the forthcoming DSM-5 definition. The diagnostic criteria for CD will remain unchanged in DSM-5, but the introduction of a specifier of CD with a callous-unemotional (CU) presentation is new. Linked to this, we discuss the pros and cons of various other ways to subtype aggression/CD symptoms. Existing guidelines for CD are, with few exceptions, already of a relatively older date and emphasize that clinical assessment should be systematic and comprehensive and based on a multi-informant approach. Non-medical psychosocial interventions are recommended as the first option for the treatment of CD. There is a role for medication in the treatment of comorbid syndromes and/or in case of insufficient response to psychosocial interventions and severe and dangerous aggressive and violent behaviours.

  12. Computational chemistry research

    Levin, Eugene

    1987-01-01

    Task 41 is composed of two parts: (1) analysis and design studies related to the Numerical Aerodynamic Simulation (NAS) Extended Operating Configuration (EOC) and (2) computational chemistry. During the first half of 1987, Dr. Levin served as a member of an advanced system planning team to establish the requirements, goals, and principal technical characteristics of the NAS EOC. A paper entitled 'Scaling of Data Communications for an Advanced Supercomputer Network' is included. The high temperature transport properties (such as viscosity, thermal conductivity, etc.) of the major constituents of air (oxygen and nitrogen) were correctly determined. The results of prior ab initio computer solutions of the Schroedinger equation were combined with the best available experimental data to obtain complete interaction potentials for both neutral and ion-atom collision partners. These potentials were then used in a computer program to evaluate the collision cross-sections from which the transport properties could be determined. A paper entitled 'High Temperature Transport Properties of Air' is included.

  13. Titanocene sulfide chemistry

    Horáček, Michal

    2016-01-01

    Roč. 314, MAY 2016 (2016), s. 83-102 ISSN 0010-8545 R&D Projects: GA ČR(CZ) GAP207/12/2368 Institutional support: RVO:61388955 Keywords : titanocene sulfide chemistry * photolysis * titanocene hydrosulfides Ti-(SH)n Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 13.324, year: 2016

  14. A green chemistry approach

    Administrator

    One-pot synthesis of quinaldine derivatives by using microwave irradiation without any solvent – A green chemistry approach. JAVAD SAFARI*, SAYED HOSSEIN BANITABA and SEPEHR SADEGH SAMIEI. Department of Chemistry, The Faculty of sciences, University of Kashan, Kashan,. P.O. Box 87317-51167, I.R. Iran.

  15. Chemistry in Microfluidic Channels

    Chia, Matthew C.; Sweeney, Christina M.; Odom, Teri W.

    2011-01-01

    General chemistry introduces principles such as acid-base chemistry, mixing, and precipitation that are usually demonstrated in bulk solutions. In this laboratory experiment, we describe how chemical reactions can be performed in a microfluidic channel to show advanced concepts such as laminar fluid flow and controlled precipitation. Three sets of…

  16. Chemistry of americium

    Schulz, W.W.

    1976-01-01

    Essential features of the descriptive chemistry of americium are reviewed. Chapter titles are: discovery, atomic and nuclear properties, collateral reading, production and uses, chemistry in aqueous solution, metal, alloys, and compounds, and, recovery, separation, purification. Author and subject indexes are included. (JCB)

  17. Movies in Chemistry Education

    Pekdag, Bulent; Le Marechal, Jean-Francois

    2010-01-01

    This article reviews numerous studies on chemistry movies. Movies, or moving pictures, are important elements of multimedia and signify a privileged or motivating means of presenting knowledge. Studies on chemistry movies show that the first movie productions in this field were devoted to university lectures or documentaries. Shorter movies were…

  18. WATER CHEMISTRY ASSESSMENT METHODS

    This section summarizes and evaluates the surfce water column chemistry assessment methods for USEPA/EMAP-SW, USGS-NAQA, USEPA-RBP, Oho EPA, and MDNR-MBSS. The basic objective of surface water column chemistry assessment is to characterize surface water quality by measuring a sui...

  19. The Breath of Chemistry

    Josephsen, Jens

    The present preliminary text is a short thematic presentation in biological inorganic chemistry meant to illustrate general and inorganic (especially coordination) chemistry in biochemistry. The emphasis is on molecular models to explain features of the complicated mechanisms essential to breathing...

  20. Exercises in Computational Chemistry

    Spanget-Larsen, Jens

    2016-01-01

    A selection of HyperChem© PC-exercises in computational chemistry. Answers to most questions are appended (Roskilde University 2014-16).......A selection of HyperChem© PC-exercises in computational chemistry. Answers to most questions are appended (Roskilde University 2014-16)....

  1. Chemistry and Biology

    Wigston, David L.

    1970-01-01

    Discusses the relationship between chemisty and biology in the science curriculum. Points out the differences in perception of the disciplines, which the physical scientists favoring reductionism. Suggests that biology departments offer a special course for chemistry students, just as the chemistry departments have done for biology students.…

  2. Contribution from philosophy of chemistry to chemistry education: In a case of ionic liquids as technochemistry

    Mudzakir, Ahmad; Hernani, Widhiyanti, Tuszie; Sudrajat, Devi Pratiwi

    2017-08-01

    Traditional chemistry education is commonly handing down of concepts, principles, and theories, such as mechanical properties, the relationship between structure and properties as well as chemical structure and chemical bonding theory, to students without engaging them in the processes of chemical inquiry. This practice leads to the lack of opportunity for the students to construct an appropriate understanding of these concepts, principles, and theories. Students are also rarely facilitated in modeling the structure and function of matter themselves. This situation shows that the philosophy of chemistry has not received as much attention from chemistry educators. The main idea of this paper is to embed philosophy of chemistry through the implementation of technochemistry in chemistry education. One of the most interesting and rapidly developing areas of modern chemistry, technologies and engineering is Ionic Liquids (ILs) as an emerging knowledge on technochemistry which can be applied to chemistry education. The developments between academic researchers and industrial developments in the ILs area are conducted in parallel. In order to overcome the existing problems of scientific development in chemistry education, the science and technology of ILs can be used for reconceptualizing the teaching and learning of chemistry to embrace the epistemology in chemistry. This study promises a potential contribution by philosophy of chemistry. The main objectives of this study are to develop: (i) a perspective based on philosophy of science considerations (rational reconstruction) in order to understand ionic liquids and (ii) teaching materials that can be used to enhance pre-service teacher's view of nature of science and technology (VNOST). The method used in the study is analytical-descriptive (elementarization), i.e. the first step in the model of educational reconstruction (MER). This study concludes that the development of the concepts and their applications of ionic

  3. Immobilization of cellulases on magnetic particles to enable enzyme recycling during hydrolysis of lignocellulose

    Alftrén, Johan

    feedstocks containing insolubles. This could potentially be overcome by immobilizing the cellulases on magnetically susceptible particles. Consequently, the immobilized cellulases could be magnetically recovered and recycled for a new cycle of enzymatic hydrolysis of cellulose. The main objective...... of this thesis was to examine the possibility of immobilizing cellulases on magnetic particles in order to enable enzyme re-use. Studies at lab and pilot scale (20 L) were conducted using model and real substrates. In paper I and III beta-glucosidase or a whole cellulase mixture was covalently immobilized...... on commercial, but expensive, magnetic particles activated with different chemistries. It was observed that the highest immobilized enzyme activities were obtained using magnetic particles activated with cyanuric chloride. In paper II biotinylated recombinant beta-glucosidase was produced and immobilized...

  4. Transuranic Computational Chemistry.

    Kaltsoyannis, Nikolas

    2018-02-26

    Recent developments in the chemistry of the transuranic elements are surveyed, with particular emphasis on computational contributions. Examples are drawn from molecular coordination and organometallic chemistry, and from the study of extended solid systems. The role of the metal valence orbitals in covalent bonding is a particular focus, especially the consequences of the stabilization of the 5f orbitals as the actinide series is traversed. The fledgling chemistry of transuranic elements in the +II oxidation state is highlighted. Throughout, the symbiotic interplay of experimental and computational studies is emphasized; the extraordinary challenges of experimental transuranic chemistry afford computational chemistry a particularly valuable role at the frontier of the periodic table. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Twisted molecular magnets

    Inglis, Ross; Milios, Constantinos J.; Jones, Leigh F.

    2012-01-01

    The use of derivatised salicylaldoximes in manganese chemistry has led to the synthesis of a family of approximately fifty hexanuclear ([Mn(III)(6)]) and thirty trinuclear ([Mn(III)(3)]) Single-Molecule Magnets (SMMs). Deliberate, targeted structural distortion of the metallic core afforded family...

  6. Third Chemistry Conference on Recent Trends in Chemistry

    Saeed, M.M.; Wheed, S.

    2011-01-01

    The third chemistry conference 2011 on recent trends in chemistry was held from October 17-19, 2001 at Islamabad, Pakistan. More than 65 papers and oral presentation. The scope of the conference was wide open and provides and opportunity for participation of broad spectrum of chemists. This forum provided a platform for the dissemination of the latest research followed by discussion pertaining to new trends in chemistry. This con fence covered different aspects of subjects including analytical chemistry, environmental chemistry, polymer chemistry, industrial chemistry, biochemistry and nano chemistry etc. (A.B.)

  7. SLC kicker magnet limitations

    Cassel, R.; Donaldson, A.; Mattison, T.; Bowden, G.; Weaver, J.; Bulos, F.; Fiander, D.

    1991-01-01

    The SLC Damping Ring kicker magnets requires a fast magnetic field rise time of 58 nsec, a peak field of 800 gauss, a pulse amplitude stability of 0.01%, and a reasonable operational lifetime. The original kicker magnets designed by SLAC and at Fermi were not able to fulfill the SLC kicker requirements. Extensive studies were conducted to determine the limitation in the magnets, response of the ferrite in kicker magnet, and the modifications needed to improve the kicker magnet performance. The paper details the SLAC and Fermi kicker magnets limitation of performance

  8. Korean Kimchi Chemistry: A Multicultural Chemistry Connection

    Murfin, Brian

    2009-01-01

    Connecting science with different cultures is one way to interest students in science, to relate science to their lives, and at the same time to broaden their horizons in a variety of ways. In the lesson described here, students make kimchi, a delicious and popular Korean dish that can be used to explore many important chemistry concepts,…

  9. Identification of Chemistry Learning Problems Viewed From Conceptual Change Model

    Redhana, I. W; Sudria, I. B. N; Hidayat, I; Merta, L. M

    2017-01-01

    This study aimed at describing and explaining chemistry learning problems viewed from conceptual change model and misconceptions of students. The study was qualitative research of case study type conducted in one class of SMAN 1 Singaraja. Subjects of the study were a chemistry teacher and students. Data were obtained through classroom observation, interviews, and conception tests. The chemistry learning problems were grouped based on aspects of necessity, intelligibility, plausibility, and f...

  10. Superconducting magnet

    1985-01-01

    Extensive computer based engineering design effort resulted in optimization of a superconducting magnet design with an average bulk current density of approximately 12KA/cm(2). Twisted, stranded 0.0045 inch diameter NbTi superconductor in a copper matrix was selected. Winding the coil from this bundle facilitated uniform winding of the small diameter wire. Test coils were wound using a first lot of the wire. The actual packing density was measured from these. Interwinding voltage break down tests on the test coils indicated the need for adjustment of the wire insulation on the lot of wire subsequently ordered for construction of the delivered superconducting magnet. Using the actual packing densities from the test coils, a final magnet design, with the required enhancement and field profile, was generated. All mechanical and thermal design parameters were then also fixed. The superconducting magnet was then fabricated and tested. The first test was made with the magnet immersed in liquid helium at 4.2K. The second test was conducted at 2K in vacuum. In the latter test, the magnet was conduction cooled from the mounting flange end.

  11. Chemistry and Nanoscience Research | NREL

    Chemistry and Nanoscience Center at NREL investigates materials and processes for converting renewable and new technologies. NREL's primary research in the chemistry and nanoscience center includes the Electrochemical Engineering and Materials Chemistry Providing a knowledge base in materials science covering

  12. System approach to chemistry course

    Lorina E. Kruglova; Valentina G. Derendyaeva

    2010-01-01

    The article considers the raise of chemistry profile for engineers and constructors training, discloses the system approach to chemistry course and singles out the most important modules from the course of general chemistry for construction industry.

  13. Department of Nuclear Physical Chemistry

    Mikulski, J.

    1994-01-01

    The research program at the Department of Nuclear Physical Chemistry of the Niewodniczanski Institute of Nuclear Physics is described. The Department consist of three laboratories. First - Laboratory of Physical Chemistry of Separation Processes on which the activity is concentrated on production and separation of neutron deficient isotopes for medical diagnostic. Recently, the main interest was in 111 In which is a promising tracer for cancer diagnostic. To increase the effectiveness of production of indium 111 In the reaction with deuterons on the enriched cadmium target was carried out instead of the previously used one with alpha particles on natural silver. In the second one - Laboratory of Chemistry and Radiochemistry - the systematic studies of physicochemical properties of transition elements in solutions are carried out. The results of the performed experiments were used for the elaboration of new rapid and selective methods for various elements. Some of these results have been applied for separation of trans actinide elements at U-400 cyclotron of JINR Dubna. The third one laboratory -Environmental Radioactivity Laboratory - conducts continuous monitoring of radioactivity contamination of atmosphere. The investigation of different radionuclides concentration in natural environment, mainly in the forest had been carried out

  14. Annual report 1987 Chemistry Department

    Funck, J.; Larsen, E.; Nielsen, O.J.

    1988-04-01

    This report contains a brief survey of the main activities in the Chemistry Department. The names and abstracts of all articles and reports published and lectures given in 1987 are presented. The facilities and equipment are mentioned briefly. The activities are divided into the following groups: radioisotope chemistry, analytical- and organic chemistry, environmental chemistry, polymer chemistry, radical chemistry, mineral processing, and general. 13 ills., (author)

  15. Annual report 1982 chemistry department

    Larsen, E.; Nielsen, O.J.

    1983-04-01

    The work going on in the Risoe National Laboratory, Chemistry Department is briefly surveyed by a presentation of all articles and reports published in 1982. The facilities and equipment are barely mentioned. The papers are divided into eight activities: 1. neutron activation analysis 2. analytical- and organic chemistry 3. environmental chemistry 4. polymer chemistry 5. geochemistry 6. radical chemistry 7. poitron annihilation 8. uranium process chemistry. (author)

  16. Annual Report 1984. Chemistry Department

    Funck, Jytte; Nielsen, Ole John

    This report contains a brief survey of the main activities in the Chemistry Department. All articles and reports published and lectures given in 1984 are presented. The facilities and equipment are mentioned briefly. The activities are divided into the following groups: radioisotope chemistry, an......, analytical- and organic chemistry, environmental chemistry, polymer chemistry, geochemistry and waste disposal, radical chemistry, positron annihilation, mineral processing, and general.......This report contains a brief survey of the main activities in the Chemistry Department. All articles and reports published and lectures given in 1984 are presented. The facilities and equipment are mentioned briefly. The activities are divided into the following groups: radioisotope chemistry...

  17. Moderator Chemistry Program

    Dewitt, L.V.; Gibbs, A.; Lambert, D.P.; Bohrer, S.R.; Fanning, R.L.; Houston, M.W.; Stinson, S.L.; Deible, R.W.; Abdel-Khalik, S.I.

    1990-11-01

    Over the past fifteen months, the Systems Chemistry Group of the Reactor Engineering Department has undertaken a comprehensive study of the Department's moderator chemistry program at Savannah River Site (SRS). An internal review was developed to formalize and document this program. Objectives were as outlined in a mission statement and action plan. In addition to the mission statement and action plan, nine separate task reports have been issued during the course of this study. Each of these task reports is included in this document as a chapter. This document is an organized compilation of the individual reports issued by the Systems Chemistry Group in assessment of SRS moderator chemistry to determine if there were significant gaps in the program as ft existed in October, 1989. While these reviews found no significant gaps in that mode of operation, or any items that adversely affected safety, items were identified that could be improved. Many of the items have already been dear with or are in the process of completion under this Moderator Chemistry Program and other Reactor Restart programs. A complete list of the items of improvement found under this assessment is found in Chapter 9, along with a proposed time table for correcting remaining items that can be improved for the chemistry program of SRS reactors. An additional external review of the moderator chemistry processes, recommendations, and responses to/from the Reactor Corrosion Mitigation Committee is included as Appendix to this compilation

  18. Chemistry of Technetium

    Omori, Takashi

    2001-01-01

    Since the late 1970's the coordination chemistry of technetium has been developed remarkably. The background of the development is obviously related to the use of technetium radiopharmaceuticals for diagnosis in nuclear medicine. Much attention has also been denoted to the chemical behavior of environmental 99 Tc released from reprocessing plants. This review covers the several aspects of technetium chemistry, including production of radioisotopes, analytical chemistry and coordination chemistry. In the analytical chemistry, separation of technetium, emphasizing chromatography and solvent extraction, is described together with spectrophotometric determination of technetium. In the coordination chemistry of technetium, a characteristic feature of the chemistry of Tc(V) complexes is referred from the view point of the formation of a wide variety of highly stable complexes containing the Tc=O or Tc≡N bond. Kinetic studies of the preparation of Tc(III) complexes using hexakis (thiourea) technetium(III) ion as a starting material are summarized, together with the base hydrolysis reactions of Tc(III), Tc(IV) and Tc(V) complexes. (author)

  19. Chemistry in water reactors

    Hermansson, H.P.; Norring, K.

    1994-01-01

    The international conference Chemistry in Water Reactors was arranged in Nice 24-27/04/1994 by the French Nuclear Energy Society. Examples of technical program areas were primary chemistry, operational experience, fundamental studies and new technology. Furthermore there were sessions about radiation field build-up, hydrogen chemistry, electro-chemistry, condensate polishing, decontamination and chemical cleaning. The conference gave the impression that there are some areas that are going to be more important than others during the next few years to come. Cladding integrity: Professor Ishigure from Japan emphasized that cladding integrity is a subject of great concern, especially with respect to waterside corrosion, deposition and release of crud. Chemistry control: The control of the iron/nickel concentration quotient seems to be not as important as previously considered. The future operation of a nuclear power plant is going to require a better control of the water chemistry than achievable today. One example of this is solubility control via regulation in BWR. Trends in USA: means an increasing use of hydrogen, minimization of SCC/IASCC, minimization of radiation fields by thorough chemistry control, guarding fuel integrity by minimization of cladding corrosion and minimization of flow assisted corrosion. Stellite replacement: The search for replacement materials will continue. Secondary side crevice chemistry: Modeling and practical studies are required to increase knowledge about the crevice chemistry and how it develops under plant operation conditions. Inhibitors: Inhibitors for IGSCC and IGA as well for the primary- (zinc) as for the secondary side (Ti) should be studied. The effects and mode of operation of the inhibitors should be documented. Chemical cleaning: of heat transfer surfaces will be an important subject. Prophylactic cleaning at regular intervals could be one mode of operation

  20. Mathematics for physical chemistry

    Mortimer, Robert G

    2013-01-01

    Mathematics for Physical Chemistry is the ideal supplementary text for practicing chemists and students who want to sharpen their mathematics skills while enrolled in general through physical chemistry courses. This book specifically emphasizes the use of mathematics in the context of physical chemistry, as opposed to being simply a mathematics text. This 4e includes new exercises in each chapter that provide practice in a technique immediately after discussion or example and encourage self-study. The early chapters are constructed around a sequence of mathematical topics, wit

  1. Gas phase ion chemistry

    Bowers, Michael T

    1979-01-01

    Gas Phase Ion Chemistry, Volume 1 covers papers on the advances of gas phase ion chemistry. The book discusses the advances in flow tubes and the measurement of ion-molecule rate coefficients and product distributions; the ion chemistry of the earth's atmosphere; and the classical ion-molecule collision theory. The text also describes statistical methods in reaction dynamics; the state selection by photoion-photoelectron coincidence; and the effects of temperature and pressure in the kinetics of ion-molecule reactions. The energy distribution in the unimolecular decomposition of ions, as well

  2. Spatially Resolved Artificial Chemistry

    Fellermann, Harold

    2009-01-01

    Although spatial structures can play a crucial role in chemical systems and can drastically alter the outcome of reactions, the traditional framework of artificial chemistry is a well-stirred tank reactor with no spatial representation in mind. Advanced method development in physical chemistry has...... made a class of models accessible to the realms of artificial chemistry that represent reacting molecules in a coarse-grained fashion in continuous space. This chapter introduces the mathematical models of Brownian dynamics (BD) and dissipative particle dynamics (DPD) for molecular motion and reaction...

  3. Experiments in physical chemistry

    Wilson, J M; Denaro, A R

    1968-01-01

    Experiments in Physical Chemistry, Second Edition provides a compilation of experiments concerning physical chemistry. This book illustrates the link between the theory and practice of physical chemistry. Organized into three parts, this edition begins with an overview of those experiments that generally have a simple theoretical background. Part II contains experiments that are associated with more advanced theory or more developed techniques, or which require a greater degree of experimental skill. Part III consists of experiments that are in the nature of investigations wherein these invest

  4. Computational quantum chemistry website

    1997-01-01

    This report contains the contents of a web page related to research on the development of quantum chemistry methods for computational thermochemistry and the application of quantum chemistry methods to problems in material chemistry and chemical sciences. Research programs highlighted include: Gaussian-2 theory; Density functional theory; Molecular sieve materials; Diamond thin-film growth from buckyball precursors; Electronic structure calculations on lithium polymer electrolytes; Long-distance electronic coupling in donor/acceptor molecules; and Computational studies of NOx reactions in radioactive waste storage

  5. Spatially Resolved Artificial Chemistry

    Fellermann, Harold

    2009-01-01

    made a class of models accessible to the realms of artificial chemistry that represent reacting molecules in a coarse-grained fashion in continuous space. This chapter introduces the mathematical models of Brownian dynamics (BD) and dissipative particle dynamics (DPD) for molecular motion and reaction......Although spatial structures can play a crucial role in chemical systems and can drastically alter the outcome of reactions, the traditional framework of artificial chemistry is a well-stirred tank reactor with no spatial representation in mind. Advanced method development in physical chemistry has...

  6. DOE fundamentals handbook: Chemistry

    1993-01-01

    The Chemistry Handbook was developed to assist nuclear facility operating contractors in providing operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of chemistry. The handbook includes information on the atomic structure of matter; chemical bonding; chemical equations; chemical interactions involved with corrosion processes; water chemistry control, including the principles of water treatment; the hazards of chemicals and gases, and basic gaseous diffusion processes. This information will provide personnel with a foundation for understanding the chemical properties of materials and the way these properties can impose limitations on the operation of equipment and systems

  7. Non-thermally activated chemistry

    Stiller, W.

    1987-01-01

    The subject is covered under the following headings: state-of-the art of non-thermally activated chemical processes; basic phenomena in non-thermal chemistry including mechanochemistry, photochemistry, laser chemistry, electrochemistry, photo-electro chemistry, high-field chemistry, magneto chemistry, plasma chemistry, radiation chemistry, hot-atom chemistry, and positronium and muonium chemistry; elementary processes in non-thermal chemistry including nuclear chemistry, interactions of electromagnetic radiations, electrons and heavy particles with matter, ionic elementary processes, elementary processes with excited species, radicalic elementary processes, and energy-induced elementary processes on surfaces and interfaces; and comparative considerations. An appendix with historical data and a subject index is given. 44 figs., 41 tabs., and 544 refs

  8. Representation and Analysis of Chemistry Core Ideas in Science Education Standards between China and the United States

    Wan, Yanlan; Bi, Hualin

    2016-01-01

    Chemistry core ideas play an important role in students' chemistry learning. On the basis of the representations of chemistry core ideas about "substances" and "processes" in the Chinese Chemistry Curriculum Standards (CCCS) and the U.S. Next Generation Science Standards (NGSS), we conduct a critical comparison of chemistry…

  9. Radionuclides in analytical chemistry

    Tousset, J.

    1984-01-01

    Applications of radionuclides in analytical chemistry are reviewed in this article: tracers, radioactive sources and activation analysis. Examples are given in all these fields and it is concluded that these methods should be used more widely [fr

  10. Electrostatics in Chemistry

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 7. Electrostatics in Chemistry - Molecular Electrostatic Potential: Visualization and Topography. Shridhar R Gadre Pravin K Bhadane. Series Article Volume 4 Issue 7 July 1999 pp 14-23 ...

  11. Organic Chemistry Masterclasses

    of Science Education that is published monthly by the Academy since January 1996. ...... Modern chemistry is also emerging from molecules derived from the .... photochemical reactions, the traditional correlation diagram approach is more ...

  12. Alcohol combustion chemistry

    Sarathy, Mani; Oß wald, Patrick; Hansen, Nils; Kohse-Hö inghaus, Katharina

    2014-01-01

    . While biofuel production and its use (especially ethanol and biodiesel) in internal combustion engines have been the focus of several recent reviews, a dedicated overview and summary of research on alcohol combustion chemistry is still lacking. Besides

  13. General Chemistry for Engineers.

    Kybett, B. D.

    1982-01-01

    Discusses the relationship between molecular structure, intermolecular forces, and tensile strengths of a polymer and suggests that this is a logical way to introduce polymers into a general chemistry course. (Author/JN)

  14. WHAT MAKES CHEMISTRY DIFFICULT?

    IICBA01

    School of Natural and Computational Science Dire Dawa University, Ethiopia,. 2 ... lack of teaching aids and the difficulty of the language of chemistry. ... lab every other week consisting of concept pretests on the web, hand-written homework, ...

  15. Indicators: Soil Chemistry

    The chemical makeup of the soil can provide information on wetland condition, wetland water quality and services being provided by the wetland ecosystem. Analyzing soil chemistry reveals if the soil is contaminated with a toxic chemical or heavy metal.

  16. BLOOD CHEMISTRY AND PLATELET SEROTONIN UPTAKE AS ...

    A cross sectional study was conducted to investigate the blood chemistry and platelet serotonin uptake as alternative method of determining HIV disease stage in HIV/AIDS patients. Whole blood was taken from subjects at the Human Virology of the Nigerian Institute of Medical Research. Subjects were judged suitable for ...

  17. Applications of supramolecular chemistry

    Schneider, Hans-Jörg

    2012-01-01

    ""The time is ripe for the present volume, which gathers thorough presentations of the numerous actually realized or potentially accessible applications of supramolecular chemistry by a number of the leading figures in the field. The variety of topics covered is witness to the diversity of the approaches and the areas of implementation…a broad and timely panorama of the field assembling an eminent roster of contributors.""-Jean-Marie Lehn, 1987 Noble Prize Winner in Chemistry

  18. Gas phase ion chemistry

    Bowers, Michael T

    1979-01-01

    Gas Phase Ion Chemistry, Volume 2 covers the advances in gas phase ion chemistry. The book discusses the stabilities of positive ions from equilibrium gas-phase basicity measurements; the experimental methods used to determine molecular electron affinities, specifically photoelectron spectroscopy, photodetachment spectroscopy, charge transfer, and collisional ionization; and the gas-phase acidity scale. The text also describes the basis of the technique of chemical ionization mass spectrometry; the energetics and mechanisms of unimolecular reactions of positive ions; and the photodissociation

  19. Reference Sources in Chemistry

    Sthapit, Dilip Man

    1995-01-01

    Information plays an important role in the development of every field. Therefore a brief knowledge regarding information sources is necessary to function in any field. There are many information sources about scientific and technical subjects. In this context there are many reference sources in Chemistry too. Chemistry is one important part of the science which deals with the study of the composition of substances and the chemical changes that they undergo. The purpose of this report is...

  20. Quantitative analysis chemistry

    Ko, Wansuk; Lee, Choongyoung; Jun, Kwangsik; Hwang, Taeksung

    1995-02-01

    This book is about quantitative analysis chemistry. It is divided into ten chapters, which deal with the basic conception of material with the meaning of analysis chemistry and SI units, chemical equilibrium, basic preparation for quantitative analysis, introduction of volumetric analysis, acid-base titration of outline and experiment examples, chelate titration, oxidation-reduction titration with introduction, titration curve, and diazotization titration, precipitation titration, electrometric titration and quantitative analysis.