Spin transport and spin torque in antiferromagnetic devices

NASA Astrophysics Data System (ADS)

Železný, J.; Wadley, P.; Olejník, K.; Hoffmann, A.; Ohno, H.

2018-03-01

Ferromagnets are key materials for sensing and memory applications. In contrast, antiferromagnets, which represent the more common form of magnetically ordered materials, have found less practical application beyond their use for establishing reference magnetic orientations via exchange bias. This might change in the future due to the recent progress in materials research and discoveries of antiferromagnetic spintronic phenomena suitable for device applications. Experimental demonstration of the electrical switching and detection of the Néel order open a route towards memory devices based on antiferromagnets. Apart from the radiation and magnetic-field hardness, memory cells fabricated from antiferromagnets can be inherently multilevel, which could be used for neuromorphic computing. Switching speeds attainable in antiferromagnets far exceed those of ferromagnetic and semiconductor memory technologies. Here, we review the recent progress in electronic spin-transport and spin-torque phenomena in antiferromagnets that are dominantly of the relativistic quantum-mechanical origin. We discuss their utility in pure antiferromagnetic or hybrid ferromagnetic/antiferromagnetic memory devices.

Exotic magnetic states in Pauli-limited superconductors.

PubMed

Kenzelmann, M

2017-03-01

Magnetism and superconductivity compete or interact in complex and intricate ways. Here we review the special case where novel magnetic phenomena appear due to superconductivity, but do not exist without it. Such states have recently been identified in unconventional superconductors. They are different from the mere coexistence of magnetic order and superconductivity in conventional superconductors, or from competing magnetic and superconducting phases in many materials. We describe the recent progress in the study of such exotic magnetic phases, and articulate the many open questions in this field.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morgan, O.B. Jr.; Berry, L.A.; Sheffield, J.

This annual report on fusion energy discusses the progress on work in the following main topics: toroidal confinement experiments; atomic physics and plasma diagnostics development; plasma theory and computing; plasma-materials interactions; plasma technology; superconducting magnet development; fusion engineering design center; materials research and development; and neutron transport. (LSP)

Magnetic and Optical Properties of Submicron-Size Hollow Spheres

PubMed Central

Ye, Quan-Lin; Yoshikawa, Hirofumi; Awaga, Kunio

2010-01-01

Magnetic hollow spheres with a controlled diameter and shell thickness have emerged as an important class of magnetic nanomaterials. The confined hollow geometry and pronouncedly curved surfaces induce unique physical properties different from those of flat thin films and solid counterparts. In this paper, we focus on recent progress on submicron-size spherical hollow magnets (e.g., cobalt- and iron-based materials), and discuss the effects of the hollow shape and the submicron size on magnetic and optical properties.

Magnetic refrigeration for low-temperature applications

NASA Technical Reports Server (NTRS)

Barclay, J. A.

1985-01-01

The application of refrigeration at low temperatures ranging from production of liquid helium for medical imaging systems to cooling of infrared sensors on surveillance satellites is discussed. Cooling below about 15 K with regenerative refrigerators is difficult because of the decreasing thermal mass of the regenerator compared to that of the working material. In order to overcome this difficulty with helium gas as the working material, a heat exchanger plus a Joule-Thomson or other exponder is used. Regenerative magnetic refrigerators with magnetic solids as the working material have the same regenerator problem as gas refrigerators. This problem provides motivation for the development of nonregenerative magnetic refrigerators that span approximately 1 K to approximately 0 K. Particular emphasis is placed on high reliability and high efficiency. Calculations indicate considerable promise in this area. The principles, the potential, the problems, and the progress towards development of successful 4 to 20 K magnetic refrigerators are discussed.

Molecular spintronics using single-molecule magnets

NASA Astrophysics Data System (ADS)

Bogani, Lapo; Wernsdorfer, Wolfgang

2008-03-01

A revolution in electronics is in view, with the contemporary evolution of the two novel disciplines of spintronics and molecular electronics. A fundamental link between these two fields can be established using molecular magnetic materials and, in particular, single-molecule magnets. Here, we review the first progress in the resulting field, molecular spintronics, which will enable the manipulation of spin and charges in electronic devices containing one or more molecules. We discuss the advantages over more conventional materials, and the potential applications in information storage and processing. We also outline current challenges in the field, and propose convenient schemes to overcome them.

The Investigation of New Magnetic Materials and Their Phenomena Using Ultrafast Fresnel Transmission Electron Microscopy

NASA Astrophysics Data System (ADS)

Schliep, Karl B.

State-of-the-art technology drives scientific progress, pushing the boundaries of our current understanding of fundamental processes and mechanisms. Our continual scientific advancement is hindered only by what we can observe and experimentally verify; thus, it is reasonable to assert that instrument development and improvement is the cornerstone for technological and intellectual growth. For example, the invention of transmission electron microscopy (TEM) allowed us to observe nanoscale phenomena for the first time in the 1930s and even now it is invaluable in the development of smaller, faster electronics. As we uncover more about the fundamentals of nanoscale phenomena, we have realized that images alone reveal only a snapshot of the story; to continue progressing we need a way to observe the entire scene unfold (e.g. how defects affect the flow of current across a transistor or how thermal energy propagates in nanoscale systems like graphene). Recently, by combining the spatial resolution of a TEM with the temporal resolution of ultrafast lasers, ultrafast electron microscopy ? or microscope ? (UEM) has allowed us to simultaneously observe transient nanoscale phenomena at ultrafast timescales. Ultrafast characterization techniques allow for the investigation of a new realm of previously unseen phenomenon inherent to the transient electronic, magnetic, and structural properties of materials. However, despite the progress made in ultrafast techniques, capturing the nanoscale spatial sub-ns temporal mechanisms and phenomenon at play in magnetic materials (especially during the operation of magnetic devices) has only recently become possible using UEM. With only a handful of instruments available, magnetic characterization using UEM is far from commonplace and any advances made are sparsely reported, and further, specific to the individual instrument. In this dissertation, I outline the development of novel magnetic materials and the establishment of a UEM lab at the University of Minnesota and how I explored the application of it toward the investigation of magnetic materials. In my discussion of UEM, I have made a concerted effort to highlight the unique challenges faced when getting a UEM lab running so that new researchers may circumvent these challenges. Of note in my graduate studies, I assisted in the development of three different magnetic material systems, strained Fe nanoparticles for permanent magnetic applications, FePd for applications in spintronic devices, and a rare-earth transition-metal (RE-TM) alloy that exhibits new magneto-optic phenomena. In studying the morphological and magnetic effects of lasers on these RE-TM alloys using the in situ laser irradiation capabilities of UEM along with standard TEM techniques and computational modeling, I uncovered a possible limitation in their utility for memory applications. Furthermore, with the aid of particle tracing software, I was able to optimize our UEM system for magnetic imaging and demonstrate the resolution of ultrafast demagnetization using UEM.

Rare-earth-free high energy product manganese-based magnetic materials.

PubMed

Patel, Ketan; Zhang, Jingming; Ren, Shenqiang

2018-06-14

The constant drive to replace rare-earth metal magnets has initiated great interest in an alternative. Manganese (Mn) has emerged to be a potential candidate as a key element in rare-earth-free magnets. Its five unpaired valence electrons give it a large magnetocrystalline energy and the ability to form several intermetallic compounds. These factors have led Mn-based magnets to be a potential replacement for rare-earth permanent magnets for several applications, such as efficient power electronics, energy generators, magnetic recording and tunneling applications, and spintronics. For past few decades, Mn-based magnets have been explored in many different forms, such as bulk magnets, thin films, and nanoparticles. Here, we review the recent progress in the synthesis and structure-magnetic property relationships of Mn-based rare-earth-free magnets (MnBi, MnAl and MnGa). Furthermore, we discuss their potential to replace rare-earth magnetic materials through the control of their structure and composition to achieve the theoretically predicted magnetic properties.

Prospects and progress of high Tc superconductivity for space applications

NASA Technical Reports Server (NTRS)

Romanofsky, Robert R.; Sokoloski, Marty M.

1991-01-01

Current research in the area of high temperature superconductivity is organized around four key areas: communications and data, sensors and cryogenics, propulsion and power, and space materials technology. Recently, laser ablated YBa2Cu3O(7-x) films on LaAlO3 produced far superior RF characteristics when compared to metallic films on the same substrate. The achievement has enabled a number of unique microwave device applications, such as low insertion loss phase shifters and high-Q filters. Melt texturing and melt-quenched techniques are being used to produce bulk material with optimized magnetic properties. These yttrium-enriched materials possess enhanced flux pinning characteristics and could lead to prototype cryocooler bearings. Significant progress has also occurred in bolometer and current lead technology. Studies were conducted to evaluate the effect of high temperature superconducting materials on the performance and life of high power magnetoplasma-dynamic thrusters. Extended studies were also performed to evaluate the benefit of superconducting magnetic energy storage for LEO space station, lunar, and Mars mission applications.

Properties of radiation stable insulation composites for fusion magnet

NASA Astrophysics Data System (ADS)

Wu, Zhixiong; Huang, Rongjin; Huang, Chuanjun; Li, Laifeng

2017-09-01

High field superconducting magnets made of Nb3Al will be a suitable candidate for future fusion device which can provide magnetic field over 15T without critical current degradation caused by strain. The higher magnetic field and the larger current will produce a huge electromagnetic force. Therefore, it is necessary to develop high strength cryogenic structural materials and electrical insulation materials with excellent performance. On the other hand, superconducting magnets in fusion devices will experience significant nuclear radiation exposure during service. While typical structural materials like stainless steel and titanium have proven their ability to withstand these conditions, electrical insulation materials used in these coils have not fared as well. In fact, recent investigations have shown that electrical insulation breakdown is a limiting factor in the performance of high field magnets. The insulation materials used in the high field fusion magnets should be characterized by excellent mechanical properties, high radiation resistivity and good thermal conductivity. To meet these objectives, we designed various insulation materials based on epoxy resins and cyanate ester resins and investigated their processing characteristic and mechanical properties before and after irradiation at low temperature. In this paper, the recent progress of the radiation stable insulation composites for high field fusion magnet is presented. The materials have been irradiated by 60Co γ-ray irradiation in air at ambient temperature with a dose rate of 300 Gy/min. The total doses of 1 MGy, 5 MGy and 10 MGy were selected to the test specimens.

Progress towards an effective model for FeSe from high-accuracy first-principles quantum Monte Carlo

NASA Astrophysics Data System (ADS)

Busemeyer, Brian; Wagner, Lucas K.

While the origin of superconductivity in the iron-based materials is still controversial, the proximity of the superconductivity to magnetic order is suggestive that magnetism may be important. Our previous work has suggested that first-principles Diffusion Monte Carlo (FN-DMC) can capture magnetic properties of iron-based superconductors that density functional theory (DFT) misses, but which are consistent with experiment. We report on the progress of efforts to find simple effective models consistent with the FN-DMC description of the low-lying Hilbert space of the iron-based superconductor, FeSe. We utilize a procedure outlined by Changlani et al.[1], which both produces parameter values and indications of whether the model is a good description of the first-principles Hamiltonian. Using this procedure, we evaluate several models of the magnetic part of the Hilbert space found in the literature, as well as the Hubbard model, and a spin-fermion model. We discuss which interaction parameters are important for this material, and how the material-specific properties give rise to these interactions. U.S. Department of Energy, Office of Science, Office of Advanced Scientific Computing Research, Scientific Discovery through Advanced Computing (SciDAC) program under Award No. FG02-12ER46875, as well as the NSF Graduate Research Fellowship Program.

New concepts for molecular magnets

NASA Astrophysics Data System (ADS)

Pilawa, Bernd

1999-03-01

Miller and Epstein (1994) define molecular magnets as magnetic materials which are prepared by the low-temperature methods of the preparative chemistry. This definition includes molecular crystals of neutral radicals, radical salts and charge transfer complexes as well as metal complexes and polymers with unpaired spins (Dormann 1995). The challenge of molecular magnets consists in tailoring magnetic properties by specific modifications of the molecular units. The combination of magnetism with mechanical or electrical properties of molecular compounds promise materials of high technical interest (Gatteschi 1994a and 1994b, Möhwald 1996) and both the chemical synthesis of new molecular materials with magnetic properties as well as the physical investigation and explanation of these properties is important, in order to achieve any progress. This work deals with the physical characterization of the magnetic properties of molecular materials. It is organized as follows. In the first part molecular crystals of neutral radicals are studied. After briefly discussing the general magnetic properties of these materials and after an overview over the physical principles of exchange interaction between organic radicals I focus on the interplay between the crystallographic structure and the magnetic properties of various derivatives of the verdazyl and nitronyl nitroxide radicals. The magnetic properties of metal complexes are the subject of the second part. After an overview over the experimental and theoretical tools which are used for the investigation of the magnetic properties I shortly discuss the exchange coupling of transition metal ions and the magnetic properties of complexes of two and three metal ions. Special emphasis is given to spin cluster compounds. Spin cluster denote complexes of many magnetic ions. They are attractive as building blocks of molecular magnets as well as magnetic model compounds for the study of spin frustration, molecular super-paramagnetism and quasi one-dimensional magnets.

Replacement and Original Magnet Engineering Options (ROMEOs): A European Seventh Framework Project to Develop Advanced Permanent Magnets Without, or with Reduced Use of, Critical Raw Materials

NASA Astrophysics Data System (ADS)

Mcguiness, P.; Akdogan, O.; Asali, A.; Bance, S.; Bittner, F.; Coey, J. M. D.; Dempsey, N. M.; Fidler, J.; Givord, D.; Gutfleisch, O.; Katter, M.; Le Roy, D.; Sanvito, S.; Schrefl, T.; Schultz, L.; Schwöbl, C.; Soderžnik, M.; Šturm, S.; Tozman, P.; Üstüner, K.; Venkatesan, M.; Woodcock, T. G.; Žagar, K.; Kobe, S.

2015-06-01

The rare-earth crisis, which peaked in the summer of 2011 with the prices of both light and heavy rare earths soaring to unprecedented levels, brought about the widespread realization that the long-term availability and price stability of rare earths could not be guaranteed. This triggered a rapid response from manufacturers involved in rare earths, as well as governments and national and international funding agencies. In the case of rare-earth-containing permanent magnets, three possibilities were given quick and serious consideration: (I) increased recycling of devices containing rare earths; (II) the search for new, mineable, rare-earth resources beyond those in China; and (III) the development of high-energy-product permanent magnets with little or no rare-earth content used in their manufacture. The Replacement and Original Magnet Engineering Options (ROMEO) project addresses the latter challenge using a two-pronged approach. With its basis on work packages that include materials modeling and advanced characterization, the ROMEO project is an attempt to develop a new class of novel permanent magnets that are free of rare earths. Furthermore, the project aims to minimize rare-earth content, particularly heavy-rare-earth (HRE) content, as much as possible in Nd-Fe-B-type magnets. Success has been achieved on both fronts. In terms of new, rare-earth-free magnets, a Heusler alloy database of 236,945 compounds has been narrowed down to approximately 20 new compounds. Of these compounds, Co2MnTi is expected to be a ferromagnet with a high Curie temperature and a high magnetic moment. Regarding the reduction in the amount of rare earths, and more specifically HREs, major progress is seen in electrophoretic deposition as a method for accurately positioning the HRE on the surface prior to its diffusion into the microstructure. This locally increases the coercivity of the rather small Nd-Fe-B-type magnet, thereby substantially reducing the dependence on the HREs Dy and Tb, two of the most critical raw materials identified by the European Commission. Overall, the ROMEO project has demonstrated that rapid progress can be achieved when experts in a specific area are brought together to focus on a particular challenge. With more than half a year of the ROMEO project remaining, further progress and additional breakthroughs can be expected.

Towards an electro-magnetic field separation of deposited material implemented in an ion beam sputter process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malobabic, Sina; Jupe, Marco; Ristau, Detlev

Nowadays, Ion Beam Sputter (IBS) processes are very well optimized on an empirical basis. To achieve further progresses, a modification of the IBS process by guiding the coating material using an axial magnetic field and an additional electrical field has been studied. The electro-magnetic (EM) field leads to a significant change in plasma properties and deposition rate distributions, whereas an increase in deposition rate along the centerline of the axial EM field around 150% was observed. These fundamental studies on the prototype are the basis for the development of an applicable and workable design of a separation device.

Chemical and magnetic properties of rapidly cooled metastable ferri-ilmenite solid solutions - IV: the fine structure of self-reversed thermoremanent magnetization

NASA Astrophysics Data System (ADS)

Robinson, Peter; McEnroe, S. A.; Fabian, K.; Harrison, R. J.; Thomas, C. I.; Mukai, H.

2014-03-01

Magnetic experiments, a Monte Carlo simulation and transmission electron microscopy observations combine to confirm variable chemical phase separation during quench and annealing of metastable ferri-ilmenite compositions, caused by inhomogeneous Fe-Ti ordering and anti-ordering. Separation begins near interfaces between growing ordered and anti-ordered domains, the latter becoming progressively enriched in ilmenite component, moving the Ti-impoverished hematite component into Fe-enriched diffusion waves near the interfaces. Even when disordered regions are eliminated, Fe-enriched waves persist and enlarge on anti-phase boundaries between growing and shrinking ordered and anti-ordered domains. Magnetic results and conceptual models show that magnetic ordering with falling T initiates in the Fe-enriched wave crests. Although representing only a tiny fraction of material, identified at highest Ts on a field-cooling curve, they control the `pre-destiny' of progressive magnetization at lower T. They can provide a positive magnetic moment in a minority of ordered ferrimagnetic material, which, by exchange coupling, then creates a self-reversed negative moment in the remaining majority. Four Ts or T ranges are recognized on typical field-cooling curves: TPD is the T range of `pre-destination'; TC is the predominant Curie T where major positive magnetization increases sharply; TMAX is where magnetization reaches a positive maximum, beyond which it is outweighed by self-reversed magnetization and TZM is the T where total magnetization passes zero. Disposition of these Ts on cooling curves indicate the fine structure of self-reversed thermoremanent magnetization. These results confirm much earlier suspicions that the `x-phase' responsible for self-reversed magnetization resides in Fe-enriched phase boundaries.

Electrostatic modification of novel materials

NASA Astrophysics Data System (ADS)

Ahn, C. H.; Bhattacharya, A.; di Ventra, M.; Eckstein, J. N.; Frisbie, C. Daniel; Gershenson, M. E.; Goldman, A. M.; Inoue, I. H.; Mannhart, J.; Millis, Andrew J.; Morpurgo, Alberto F.; Natelson, Douglas; Triscone, Jean-Marc

2006-10-01

Application of the field-effect transistor principle to novel materials to achieve electrostatic doping is a relatively new research area. It may provide the opportunity to bring about modifications of the electronic and magnetic properties of materials through controlled and reversible changes of the carrier concentration without modifying the level of disorder, as occurs when chemical composition is altered. As well as providing a basis for new devices, electrostatic doping can in principle serve as a tool for studying quantum critical behavior, by permitting the ground state of a system to be tuned in a controlled fashion. In this paper progress in electrostatic doping of a number of materials systems is reviewed. These include structures containing complex oxides, such as cuprate superconductors and colossal magnetoresistive compounds, organic semiconductors, in the form of both single crystals and thin films, inorganic layered compounds, single molecules, and magnetic semiconductors. Recent progress in the field is discussed, including enabling experiments and technologies, open scientific issues and challenges, and future research opportunities. For many of the materials considered, some of the results can be anticipated by combining knowledge of macroscopic or bulk properties and the understanding of the field-effect configuration developed during the course of the evolution of conventional microelectronics. However, because electrostatic doping is an interfacial phenomenon, which is largely an unexplored field, real progress will depend on the development of a better understanding of lattice distortion and charge transfer at interfaces in these systems.

Coupled multiferroic domain switching in the canted conical spin spiral system Mn2GeO4

NASA Astrophysics Data System (ADS)

Honda, T.; White, J. S.; Harris, A. B.; Chapon, L. C.; Fennell, A.; Roessli, B.; Zaharko, O.; Murakami, Y.; Kenzelmann, M.; Kimura, T.

2017-06-01

Despite remarkable progress in developing multifunctional materials, spin-driven ferroelectrics featuring both spontaneous magnetization and electric polarization are still rare. Among such ferromagnetic ferroelectrics are conical spin spiral magnets with a simultaneous reversal of magnetization and electric polarization that is still little understood. Such materials can feature various multiferroic domains that complicates their study. Here we study the multiferroic domains in ferromagnetic ferroelectric Mn2GeO4 using neutron diffraction, and show that it features a double-Q conical magnetic structure that, apart from trivial 180o commensurate magnetic domains, can be described by ferromagnetic and ferroelectric domains only. We show unconventional magnetoelectric couplings such as the magnetic-field-driven reversal of ferroelectric polarization with no change of spin-helicity, and present a phenomenological theory that successfully explains the magnetoelectric coupling. Our measurements establish Mn2GeO4 as a conceptually simple multiferroic in which the magnetic-field-driven flop of conical spin spirals leads to the simultaneous reversal of magnetization and electric polarization.

Building blocks for correlated superconductors and magnets

DOE PAGES

Sarrao, J. L.; Ronning, F.; Bauer, E. D.; ...

2015-04-01

Recent efforts at Los Alamos to discover strongly correlated superconductors and hard ferromagnets are reviewed. While serendipity remains a principal engine of materials discovery, design principles and structural building blocks are beginning to emerge that hold potential for predictive discovery. In addition, successes over the last decade with the so-called “115” strongly correlated superconductors are summarized, and more recent efforts to translate these insights and principles to novel hard magnets are discussed. While true “materials by design” remains a distant aspiration, progress is being made in coupling empirical design principles to electronic structure simulation to accelerate and guide materials designmore » and synthesis.« less

Recent progress in research on tungsten materials for nuclear fusion applications in Europe

NASA Astrophysics Data System (ADS)

Rieth, M.; Dudarev, S. L.; Gonzalez de Vicente, S. M.; Aktaa, J.; Ahlgren, T.; Antusch, S.; Armstrong, D. E. J.; Balden, M.; Baluc, N.; Barthe, M.-F.; Basuki, W. W.; Battabyal, M.; Becquart, C. S.; Blagoeva, D.; Boldyryeva, H.; Brinkmann, J.; Celino, M.; Ciupinski, L.; Correia, J. B.; De Backer, A.; Domain, C.; Gaganidze, E.; García-Rosales, C.; Gibson, J.; Gilbert, M. R.; Giusepponi, S.; Gludovatz, B.; Greuner, H.; Heinola, K.; Höschen, T.; Hoffmann, A.; Holstein, N.; Koch, F.; Krauss, W.; Li, H.; Lindig, S.; Linke, J.; Linsmeier, Ch.; López-Ruiz, P.; Maier, H.; Matejicek, J.; Mishra, T. P.; Muhammed, M.; Muñoz, A.; Muzyk, M.; Nordlund, K.; Nguyen-Manh, D.; Opschoor, J.; Ordás, N.; Palacios, T.; Pintsuk, G.; Pippan, R.; Reiser, J.; Riesch, J.; Roberts, S. G.; Romaner, L.; Rosiński, M.; Sanchez, M.; Schulmeyer, W.; Traxler, H.; Ureña, A.; van der Laan, J. G.; Veleva, L.; Wahlberg, S.; Walter, M.; Weber, T.; Weitkamp, T.; Wurster, S.; Yar, M. A.; You, J. H.; Zivelonghi, A.

2013-01-01

The current magnetic confinement nuclear fusion power reactor concepts going beyond ITER are based on assumptions about the availability of materials with extreme mechanical, heat, and neutron load capacity. In Europe, the development of such structural and armour materials together with the necessary production, machining, and fabrication technologies is pursued within the EFDA long-term fusion materials programme. This paper reviews the progress of work within the programme in the area of tungsten and tungsten alloys. Results, conclusions, and future projections are summarized for each of the programme's main subtopics, which are: (1) fabrication, (2) structural W materials, (3) W armour materials, and (4) materials science and modelling. It gives a detailed overview of the latest results on materials research, fabrication processes, joining options, high heat flux testing, plasticity studies, modelling, and validation experiments.

Progress towards Growth and Characterization of Rare-Earth Nanoparticles using the Inverse Micelle Method

NASA Astrophysics Data System (ADS)

Romero, Dulce G.; Ho, Pei-Chun

2008-03-01

Nano-sized particles and clusters have promising electrical, chemical, and magnetic properties as compared to the bulk materials. Due to their reduced dimensionality, it makes their physical properties significantly different from the bulk material. The nano-sized materials have great potential for technical applications, such as, magnetic information storage, imaging, medical devices, and magnetic refrigeration. In this report, we will present the preliminary results on the growth and characterization of rare-earth metallic nanoparticles of Gd and Nd synthesized by the inverse micelle method [1]. These results will be compared to the bulk properties of Gd and Nd, as well as, to those exhibited by metallic nanoparticles, such as Co (by inverse micelle), and Gd (by laser evaporation cluster source), which have been found to show superparamagnetic behavior, enhanced magnetization, and self-organization [2-4]. [1] X.M. Lin, et al. Langmuir. 14, 7140 (1998). [2] D.C. Douglass, et al. Phys. Rev. B. 47, 19 (1993). [3] C. Petit, et al. Advanced Materials. 10, 259 (1998). [4] J.P. Chen, et al. Phys. Rev. B. 51, 11527 (1995).

Progress of applied superconductivity research at Materials Research Laboratories, ITRI (Taiwan)

NASA Technical Reports Server (NTRS)

Liu, R. S.; Wang, C. M.

1995-01-01

A status report based on the applied high temperature superconductivity (HTS) research at Materials Research Laboratories (MRL), Industrial Technology Research Institute (ITRI) is given. The aim is to develop fabrication technologies for the high-TC materials appropriate to the industrial application requirements. To date, the majorities of works have been undertaken in the areas of new materials, wires/tapes with long length, prototypes of magnets, large-area thin films, SQUID's and microwave applications.

High-frequency rotational losses in different soft magnetic composites

NASA Astrophysics Data System (ADS)

de la Barrière, O.; Appino, C.; Ragusa, C.; Fiorillo, F.; Mazaleyrat, F.; LoBue, M.

2014-05-01

The isotropic properties of Soft Magnetic Composites (SMC) favor the design of new machine topologies and their granular structure can induce a potential decrease of the dynamic loss component. This paper is devoted to the characterization of the broadband magnetic losses of different SMC types under alternating and circular induction. The investigated materials differ by their grain size, heat treatment, compaction rate, and binder type. It is shown that, up to peak polarization Jp = 1.25 T, the ratios between the rotational and the alternating loss components (classical, hysteresis, and excess) are quite independent of the material structural details, quite analogous to the known behavior of nonoriented steel laminations. On the contrary, at higher inductions, it is observed that the Jp value at which the rotational hysteresis loss attains its maximum, related to the progressive disappearance of the domain walls under increasing rotational fields, decreases with the material susceptibility.

Magneto-structural correlations in rare-earth cobalt pnictides

NASA Astrophysics Data System (ADS)

Thompson, Corey Mitchell

Magnetic materials are used in many applications such as credit cards, hard drives, electric motors, sensors, etc. Although a vast range of magnetic solids is available for these purposes, our ability to improve their efficiency and discover new materials remains paramount to the sustainable progress and economic profitability in many technological areas. The search for magnetic solids with improved performance requires fundamental understanding of correlations between the structural, electronic, and magnetic properties of existing materials, as well as active exploratory synthesis that targets the development of new magnets. Some of the strongest permanent magnets, Nd 2Fe14B, SmCo5, and Sm2Co17, combine transition and rare-earth metals, benefiting from the strong exchange between the 4f and 3d magnetic sublattices. Although these materials have been studied in great detail, the development of novel magnets requires thorough investigation of other 3d-4 f intermetallics, in order to gain further insights into correlations between their crystal structures and magnetic properties. Among many types of intermetallic materials, ternary pnictides RCo 2Pn2 (R = La, Ce, Pr, Nd; Pn = P, As) are of interest because, despite their simple crystal structures, they contain two magnetic sublattices, exchange interactions between which may lead to rich and unprecedented magnetic behavior. Nevertheless, magnetism of these materials was studied only to a limited extent, especially as compared to the extensive studies of their silicide and germanide analogues. The ThCr2Si2 structure type, to which these ternary pnictides belong, is one of the most ubiquitous atomic arrangements encountered among intermetallic compounds. It accounts for over 1000 known intermetallics and has received increased attention due to the recently discovered FeAs-based superconductors. This dissertation is devoted to the investigation of magnetostructural relationships and anomalous magnetic behaviors in rare earth-cobalt pnictides with the ThCr2Si2 structure type, as well as to the development of new synthetic approaches to the preparation of such materials. We use iso- and aliovalent substitutions as effective tools to probe magnetostructural correlations and establish general trends in the magnetic behavior of RCo 2Pn2 phases. The modification of the electronic band structure, which correlates with the changes in the crystal structure of the material, is found to act as the driving force that dictates the magnetic properties of these itinerant systems. We demonstrate how this knowledge can be used effectively to achieve diverse magnetic properties and relate them to specific structural characteristics of materials.

Recent progress on magnetic iron oxide nanoparticles: synthesis, surface functional strategies and biomedical applications

PubMed Central

Wu, Wei; Wu, Zhaohui; Yu, Taekyung; Jiang, Changzhong; Kim, Woo-Sik

2015-01-01

This review focuses on the recent development and various strategies in the preparation, microstructure, and magnetic properties of bare and surface functionalized iron oxide nanoparticles (IONPs); their corresponding biological application was also discussed. In order to implement the practical in vivo or in vitro applications, the IONPs must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of IONPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The new functionalized strategies, problems and major challenges, along with the current directions for the synthesis, surface functionalization and bioapplication of IONPs, are considered. Finally, some future trends and the prospects in these research areas are also discussed. PMID:27877761

FOREWORD: Focus on Materials Analysis and Processing in Magnetic Fields Focus on Materials Analysis and Processing in Magnetic Fields

NASA Astrophysics Data System (ADS)

Sakka, Yoshio; Hirota, Noriyuki; Horii, Shigeru; Ando, Tsutomu

2009-03-01

Recently, interest in the applications of feeble (diamagnetic and paramagnetic) magnetic materials has grown, whereas the popularity of ferromagnetic materials remains steady and high. This trend is due to the progress of superconducting magnet technology, particularly liquid-helium-free superconducting magnets that can generate magnetic fields of 10 T and higher. As the magnetic energy is proportional to the square of the applied magnetic field, the magnetic energy of such 10 T magnets is in excess of 10 000 times that of conventional 0.1 T permanent magnets. Consequently, many interesting phenomena have been observed over the last decade, such as the Moses effect, magnetic levitation and the alignment of feeble magnetic materials. Researchers in this area are widely spread around the world, but their number in Japan is relatively high, which might explain the success of magnetic field science and technology in Japan. Processing in magnetic fields is a rapidly expanding research area with a wide range of promising applications in materials science. The 3rd International Workshop on Materials Analysis and Processing in Magnetic Fields (MAP3), which was held on 14-16 May 2008 at the University of Tokyo, Japan, focused on various topics including magnetic field effects on chemical, physical, biological, electrochemical, thermodynamic and hydrodynamic phenomena; magnetic field effects on the crystal growth and processing of materials; diamagnetic levitation, the magneto-Archimedes effect, spin chemistry, magnetic orientation, control of structure by magnetic fields, magnetic separation and purification, magnetic-field-induced phase transitions, properties of materials in high magnetic fields, the development of NMR and MRI, medical applications of magnetic fields, novel magnetic phenomena, physical property measurement by magnetic fields, and the generation of high magnetic fields. This focus issue compiles 13 key papers selected from the proceedings of MAP3. Other papers of the proceedings are published in Journal of Physics: Conference Series. Tournier and Beaugnon review experimental texturing in metallic melts by cooling in magnetic fields, which is modeled in detail in a study by Tournier. Wang et al provide further experimental results on the solidification of Mn-90.4 wt % Sb alloy in magnetic fields. The orientations of grains and particles induced by magnetic fields is reported by Horii et al (rare-earth-doped cuprates), Tanaka et al (barium-bismuth titanate ceramics), Liu and Schwartz (Bi2Sr2CaCu2Ox/AgMg wires) and Tsuda and Sakka (carbon nanotubes). Gielen et al present a model of how to quantify a molecular alignment using magnetic birefringence, and Ando et al simulate the movement of feeble particles in magnetic fields. Hirota et al report the experimental control of the lattice constant in a triangular lattice of feeble magnetic particles. The size separation of diamagnetic particles by magnetic fields is experimentally studied by Tarn et al and theoretically studied by Fukui et al. A setup measuring x-ray diffraction patterns in magnetic fields up to 5 T and temperatures above 200 oC has been developed by Mitsui et al. We hope that this focus issue will help readers to understand several aspects of materials analysis and processing in magnetic fields at the frontier of the science.

The rise of 3-d single-ion magnets in molecular magnetism: towards materials from molecules?

PubMed Central

Frost, Jamie M.; Harriman, Katie L. M.

2016-01-01

Single-molecule magnets (SMMs) that contain one spin centre (so-called single-ion magnets) theoretically represent the smallest possible unit for spin-based electronic devices. The realisation of this and related technologies, depends on first being able to design systems with sufficiently large energy barriers to magnetisation reversal, U eff, and secondly, on being able to organise these molecules into addressable arrays. In recent years, significant progress has been made towards the former goal – principally as a result of efforts which have been directed towards studying complexes based on highly anisotropic lanthanide ions, such as Tb(iii) and Dy(iii). Since 2013 however, and the remarkable report by Long and co-workers of a linear Fe(i) system exhibiting U eff = 325 K, single-ion systems of transition metals have undergone something of a renaissance in the literature. Not only do they have important lessons to teach us about anisotropy and relaxation dynamics in the quest to enhance U eff, the ability to create strongly coupled spin systems potentially offers access to a whole of host of 1, 2 and 3-dimensional materials with interesting structural and physical properties. This perspective summarises recent progress in this rapidly expanding sub-genre of molecular magnetism from the viewpoint of the synthetic chemist, with a particular focus on the lessons that have so far been learned from single-ion magnets of the d-block, and, the future research directions which we feel are likely to emerge in the coming years. PMID:28660017

Antiferroelectric Materials, Applications and Recent Progress on Multiferroic Heterostructures

NASA Astrophysics Data System (ADS)

Zhou, Ziyao; Yang, Qu; Liu, Ming; Zhang, Zhiguo; Zhang, Xinyang; Sun, Dazhi; Nan, Tianxiang; Sun, Nianxiang; Chen, Xing

2015-04-01

Antiferroelectric (AFE) materials with adjacent dipoles oriented in antiparallel directions have a double polarization hysteresis loops. An electric field (E-field)-induced AFE-ferroelectric (FE) phase transition takes place in such materials, leading to a large lattice strain and energy change. The high dielectric constant and the distinct phase transition in AFE materials provide great opportunities for the realization of energy storage devices like super-capacitors and energy conversion devices such as AFE MEMS applications. Lots of work has been done in this field since 60-70 s. Recently, the strain tuning of the spin, charge and orbital orderings and their interactions in complex oxides and multiferroic heterostructures have received great attention. In these systems, a single control parameter of lattice strain is used to control lattice-spin, lattice-phonon, and lattice-charge interactions and tailor properties or create a transition between distinct magnetic/electronic phases. Due to the large strain/stress arising from the phase transition, AFE materials are great candidates for integrating with ferromagnetic (FM) materials to realize in situ manipulation of magnetism and lattice-ordered parameters by voltage. In this paper, we introduce the AFE material and it's applications shortly and then review the recent progress in AFEs based on multiferroic heterostructures. These new multiferroic materials could pave a new way towards next generation light, compact, fast and energy efficient voltage tunable RF/microwave, spintronic and memory devices promising approaches to in situ manipulation of lattice-coupled order parameters is to grow epitaxial oxide films on FE/ferroelastic substrates.

FOREWORD: Focus on Magneto-Science

NASA Astrophysics Data System (ADS)

Tanimoto, Yoshifumi; Beaugnon, Eric; Kimura, Tsunehisa; Ozeki, Sumio

2008-06-01

Magnetite, a natural magnetic material, was discovered in China several thousand years ago. Since then, many ancient people have been fascinated by the interesting properties of magnetite. Similarly, many scientists have dreamed of manipulating chemical, physical and biological phenomena using magnetic fields. Despite the long time that has passed since the discovery of magnetite, this dream has only recently been accomplished. Magnetism, an important physical property of materials, is of three types: diamagnetism, paramagnetism and ferromagnetism. The magnetic susceptibilities of diamagnetic, paramagnetic and ferromagnetic materials are in the order of -10-10, +10-8 and +10-2 m3 mol-1, respectively. Note that most commonly used materials such as water and benzene are diamagnetic; air is paramagnetic. The magnetic energy of diamagnetic and paramagnetic (magnetically weak) materials under a magnetic field of 1 T, which is the maximum field generated by a tabletop electromagnet, is very small compared with the thermal energy at room temperature. Therefore, it is difficult to believe that a magnetic field less than 1 T markedly affects the chemical and physical phenomena of magnetically weak materials. Recently, the progress of superconducting magnet manufacturing technology has enabled us to freely use strong magnetic fields of 10 T or more in our laboratories. Because magnetic energy is proportional to the square of the magnetic flux density, the magnetic energy at 10 T, for example, is 100 times greater than that at 1 T, indicating that the effect of a 10 T magnetic field on magnetically weak materials becomes so great that magnetic phenomena, which cannot be observed in a 1 T field, are very clear in a 10 T field. Consequently, many interesting phenomena have been observed. For example, it was demonstrated that water in a vessel could be separated into two parts by applying strong horizontal magnetic fields to create the so-called Moses effect. Reportedly, diamagnetic materials such as water and wood can be levitated by applying vertical magnetic fields: magnetic levitation. These phenomena are interpreted in terms of magnetic force. Although the effect of a magnetic force has been well investigated both theoretically and experimentally, before these reports it was difficult to imagine that water could be separated or levitated using magnetic fields, simply because the magnetic force generated by a tabletop electromagnet is not strong enough to demonstrate these phenomena clearly. The magnetic phenomena occurring under a 10 T field markedly differ from those under a 1 T field: strong magnetic fields of approximately 10 T present researchers with a new interdisciplinary field of science, encompassing physics, chemistry and biology, which will also be useful for technological development. Taking these benefits into account, we adopted the term 'magneto-science' (basic and applied), to refer to the investigation of magnetic field effects (MFEs) on physical, chemical and biological phenomena in order to differentiate this new interdisciplinary field from traditional ones. In consideration of the important role of magneto-science in the 21st century, this focus issue contains 16 articles selected from the International Conference on Magneto-Science (ICMS2007), which was held in Hiroshima, Japan in November 2007. The selected papers describe various studies of MFEs (≤ 16 T) in hard, soft and biological materials. Topics such as the magnetic processing of alloys or hard materials, spin chemistry and spin dynamics, magneto-electrochemistry, the magnetic processing of soft materials, the applications of magnetic fields to analysis, and magneto-biology are addressed to delineate the frontiers of magneto-science. We hope that this focus issue will help readers to understand several aspects of the frontiers of magneto-science.

Development of superconducting YBa2Cu3O(x) wires with low resistance electrical contacts

NASA Technical Reports Server (NTRS)

Buoncristiani, A. M.; Byvik, C. E.; Caton, R.; Selim, R.; Lee, B. I.; Modi, V.; Sherrill, M.; Leigh, H. D.; Fain, C. C.; Lewis, G.

1993-01-01

Materials exhibiting superconductivity above liquid nitrogen temperatures (77 K) will enable new applications of this phenomena. One of the first commercial applications of this technology will be superconducting magnets for medical imaging. However, a large number of aerospace applications of the high temperature superconducting materials have also been identified. These include magnetic suspension and balance of models in wind tunnels and resistanceless leads to anemometers. The development of superconducting wires fabricated from the ceramic materials is critical for these applications. The progress in application of a patented fiber process developed by Clemson University for the fabrication of superconducting wires is reviewed. The effect of particle size and heat treatment on the quality of materials is discussed. Recent advances made at Christopher Newport College in the development of micro-ohm resistance electrical contacts which are capable of carrying the highest reported direct current to this material is presented.

Development of superconducting YBa2Cu3O(x) wires with low resistance electrical contacts

NASA Astrophysics Data System (ADS)

Buoncristiani, A. M.; Byvik, C. E.; Caton, R.; Selim, R.; Lee, B. I.; Modi, V.; Sherrill, M.; Leigh, H. D.; Fain, C. C.; Lewis, G.

Materials exhibiting superconductivity above liquid nitrogen temperatures (77 K) will enable new applications of this phenomena. One of the first commercial applications of this technology will be superconducting magnets for medical imaging. However, a large number of aerospace applications of the high temperature superconducting materials have also been identified. These include magnetic suspension and balance of models in wind tunnels and resistanceless leads to anemometers. The development of superconducting wires fabricated from the ceramic materials is critical for these applications. The progress in application of a patented fiber process developed by Clemson University for the fabrication of superconducting wires is reviewed. The effect of particle size and heat treatment on the quality of materials is discussed. Recent advances made at Christopher Newport College in the development of micro-ohm resistance electrical contacts which are capable of carrying the highest reported direct current to this material is presented.

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

USGS Publications Warehouse

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

2011-01-01

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

Thermally actuated magnetization flux pump in single-grain YBCO bulk

NASA Astrophysics Data System (ADS)

Yan, Yu; Li, Quan; Coombs, T. A.

2009-10-01

Recent progress in material processing has proved that high temperature superconductors (HTS) have a great potential to trap large magnetic fields at cryogenic temperatures. For example, HTS are widely used in MRI scanners and in magnetic bearings. However, using traditional ways to magnetize, the YBCO will always need the applied field to be as high as the expected field on the superconductor or much higher than it, leading to a much higher cost than that of using permanent magnets. In this paper, we find a method of YBCO magnetization in liquid nitrogen that only requires the applied field to be at the level of a permanent magnet. Moreover, rather than applying a pulsed high current field on the YBCO, we use a thermally actuated material (gadolinium) as an intermedia and create a travelling magnetic field through it by changing the partial temperature so that the partial permeability is changed to build up the magnetization of the YBCO gradually after multiple pumps. The gadolinium bulk is located between the YBCO and the permanent magnet and is heated and cooled repeatedly from the outer surface to generate a travelling thermal wave inwards. In the subsequent experiment, an obvious accumulation of the flux density is detected on the surface of the YBCO bulk.

Magnetization manipulation in multiferroic devices.

NASA Astrophysics Data System (ADS)

Gajek, Martin; Martin, Lane; Hao Chu, Ying; Huijben, Mark; Barry, Micky; Ramesh, Ramamoorthy

2008-03-01

Controlling magnetization by purely electrical means is a a central topic in spintronics. A very recent route towards this goal is to exploit the coupling between multiple ferroic orders which coexist in multiferroic materials. BiFeO3 (BFO) displays antiferromagnetic and ferroelectric orderings at room temperature and can thus be used as an electrically controllable pinning layer for a ferromagnetic electrode. Furthermore BFO remains ferroelectric down to 2nm and can therefore be integrated as a tunnel barrier in MTJ's. We will describe these two architecture schemes and report on our progresses towards the control of magnetization via the multiferroic layer in those structures.

Review of high field superconducting magnet development at Oxford Instruments

NASA Astrophysics Data System (ADS)

Brown, F. J.; Kerley, N. W.; Knox, R. B.; Timms, K. W.

1996-02-01

Present commercial development activity for high field superconducting magnets is focused clearly in three directions. The development of solenoid magnets with flux densities in excess of 20 T, the production of highly homogeneous fields at 20 T, and development of large split pair magnets in excess of 12 T. Recent developments in split pair technology allows us to build magnets with useful access, transverse to the field, up to 15 T. Compact solenoid magnets to 20 T have been available commercially for over 3 yr now with a progressive increment in bore size, providing associated engineering challenges. A 20 T solenoid with a clear bore of 52 mm and a homogeneity of 0.1% is now a standard production item. Improving the homogeneity to the 1 ppm level involves re-assessment of critical design parameters and choice of materials. Our development over the last twelve months has culminated in a 20 T solenoid with base homogeneity of 5 ppm over a 10 mm sphere. In order to realise persistent fields in excess of 20 T, requires the priority on development to be switched from engineering and manufacturing towards material development and enhancement. We present the findings and conclusions of our high field development program over the last 3 yr, together with an outline of our requirements and activities in materials and engineering leading to the next step in high field magnet manufacture, using conventional low Tc conductors.

Review of progress in quantitative NDE. [Nondestructive Evaluation (NDE)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1991-01-01

This booklet is composed of abstracts from papers submitted at a meeting on quantitative NDE. A multitude of topics are discussed including analysis of composite materials, NMR uses, x-ray instruments and techniques, manufacturing uses, neural networks, eddy currents, stress measurements, magnetic materials, adhesive bonds, signal processing, NDE of mechanical structures, tomography,defect sizing, NDE of plastics and ceramics, new techniques, optical and electromagnetic techniques, and nonlinear techniques. (GHH)

Progress In Magnetized Target Fusion Driven by Plasma Liners

NASA Technical Reports Server (NTRS)

Thio, Francis Y. C.; Kirkpatrick, Ronald C.; Knapp, Charles E.; Cassibry, Jason; Eskridge, Richard; Lee, Michael; Smith, James; Martin, Adam; Wu, S. T.; Schmidt, George;

Developing a Magnetic Resonance Imaging measurement of the forces within 3D granular materials under external loads

NASA Astrophysics Data System (ADS)

Elrington, Stefan; Bertrand, Thibault; Frey, Merideth; Shattuck, Mark; O'Hern, Corey; Barrett, Sean

2014-03-01

Granular materials are comprised of an ensemble of discrete macroscopic grains that interact with each other via highly dissipative forces. These materials are ubiquitous in our everyday life ranging in scale from the granular media that forms the Earth's crust to that used in agricultural and pharmaceutical industries. Granular materials exhibit complex behaviors that are poorly understood and cannot be easily described by statistical mechanics. Under external loads individual grains are jammed into place by a network of force chains. These networks have been imaged in quasi two-dimensional and on the outer surface of three-dimensional granular materials. Our goal is to use magnetic resonance imaging (MRI) to detect contact forces deep within three-dimensional granular materials, using hydrogen-1 relaxation times as a reporter for changes in local stress and strain. To this end, we use a novel pulse sequence to narrow the line width of hydrogen-1 in rubber. Here we present our progress to date, and prospects for future improvements.

Deep Magnetic Diagenesis in Sediments: Progressive and Punctuated Processes.

NASA Astrophysics Data System (ADS)

Musgrave, R. J.; Kars, M. A. C.; Vega, M. E.

2017-12-01

Magnetic diagenesis in the tuffaceous muds, mudstones and volcaniclastic rocks cored at IODP Site U1437 is a product of progressive processes that continue throughout the 1800-m-thick sequence, punctuated by superimposed features corresponding to a series of influxes of fluids and concentrations of hydrocarbons. XRD, visual examination and SEM images indicate the presence of both magnetite and the magnetic sulfide greigite. Inferences from high values of saturation isothermal remanence normalised by magnetic susceptibility (SIRM/χ), distribution of hysteresis data near a diagenetic greigite curve on a Day plot, and 'humping' of low-temperature cycles of SIRM suggest that detrital magnetite and diagenetic greigite are both significant contributors to the magnetic assemblage, with greigite constituting a higher proportion in shallower samples. Progressive magnetic diagenesis is expressed as a continuing background decrease in SIRM/χ. FORC curves indicate an initial diagenetic growth of one or more higher-coercivity phases, followed downhole by increasing loss of all but low-coercivity material. The downhole pattern is consistent with progressive loss of fine-grained magnetite, initial authigenesis of greigite, and progressive pyritisation of the greigite. Some coarse-grained samples from the base of the sequence buck the trend, exhibiting SD behavior probably related to surviving magnetite inclusions in silicates. Shipboard fluid analysis revealed a complex profile of interstitial-water geochemistry, marked by several fluid influxes, including inputs of sulfate-rich water at about 275 and 460 meters below seafloor (mbsf). Methane concentrations, mostly low, markedly increase in the interval between 750 and 1460 mbsf, and ethane appears below an inferred fault at 1104 mbsf. Each of these fluid events is marked by offsets in the rock magnetic parameters SIRM/χ, S-0.3T, and DJH, representing repeated phases of late diagenetic growth of greigite in response to supplies of sulfate, intervals of enhanced pyritisation of greigite where concentrations of deeply sourced methane may be accompanied by H2S, and a more enigmatic response to the thermogenic ethane interval which seems to both dissolve any remaining fine-grained magnetite and grow a new generation of greigite.

Magnetic nanomaterials and sensors for biological detection.

PubMed

Sobczak-Kupiec, Agnieszka; Venkatesan, Jayachandran; Alhathal AlAnezi, Adnan; Walczyk, Dorota; Farooqi, Ammad; Malina, Dagmara; Hosseini, Seyed Hossein; Tyliszczak, Bozena

2016-11-01

It is becoming progressively more understandable that sensitivity and versatility of magnetic biosensors provides unique platform for high performance diagnostics in clinical settings. Confluence of information suggested that magnetic biosensors required well-tailored magnetic particles as probes for detection that generate large and specific biological signal with minimum possible nonspecific binding. However, there are visible knowledge gaps in our understanding of the strategies to overcome existing challenges related to even smaller size of intracellular targets and lower signal-to-noise ratio than that in whole-cell studies, therefore tool designing and development for intracellular measurement and manipulation is problematic. In this review we describe magnetic nanoparticles, synthesis and sensing principles of magnetic nanoparticles as well as surface functionalization and modification and finally magnetic nanoparticles for medical diagnostics. This review gathers important and up-to-date information and may help to develop the method of obtaining magnetic materials especially for medical application. Copyright © 2016 Elsevier Inc. All rights reserved.

Multidimensional Simulations of Filament Channel Structure and Evolution

NASA Astrophysics Data System (ADS)

Karpen, J. T.

2007-10-01

Over the past decade, the NRL Solar Theory group has made steady progress toward formulating a comprehensive model of filament-channel structure and evolution, combining the results of our sheared 3D arcade model for the magnetic field with our thermal nonequilibrium model for the cool, dense material suspended in the corona. We have also discovered that, when a sheared arcade is embedded within the global dipolar field, the resulting stressed filament channel can erupt through the mechanism of magnetic breakout. Our progress has been largely enabled by the development and implementation of state-of-the-art 1D hydrodynamic and 3D magnetohydrodynamic (MHD) codes to simulate the field-aligned plasma thermodynamics and large-scale magnetic-field evolution, respectively. Significant questions remain, however, which could be answered with the advanced observations anticipated from Solar-B. In this review, we summarize what we have learned from our simulations about the magnetic and plasma structure, evolution, and eruption of filament channels, and suggest key observational objectives for Solar-B that will test our filament-channel and CME-initiation models and augment our understanding of the underlying physical processes.

A motionless actuation system for magnetic shape memory devices

NASA Astrophysics Data System (ADS)

Armstrong, Andrew; Finn, Kevin; Hobza, Anthony; Lindquist, Paul; Rafla, Nader; Müllner, Peter

2017-10-01

Ni-Mn-Ga is a Magnetic Shape Memory (MSM) alloy that changes shape in response to a variable magnetic field. We can intentionally manipulate the shape of the material to function as an actuator, and the material can thus replace complicated small electromechanical systems. In previous work, a very simple and precise solid-state micropump was developed, but a mechanical rotation was required to translate the position of the magnetic field. This mechanical rotation defeats the purpose of the motionless solid-state device. Here we present a solid-state electromagnetic driver to linearly progress the position of the applied magnetic field and the associated shrinkage. The generated magnetic field was focused at either of two pole pieces, providing a mechanism for moving the localized shrinkage in the MSM element. We confirmed that our driver has sufficient strength to actuate the MSM element using optical microscopy. We validated the whole design by comparing results obtained with finite element analysis with the experimentally measured flux density. This drive system serves as a possible replacement to the mechanical rotation of the magnetic field by using a multi-pole electromagnet that sweeps the magnetic field across the MSM micropump element, solid-state switching the current to each pole piece in the multi-pole electromagnet.

APPARATUS FOR THE DENSIFICATION AND ENERGIZATION OF CHARGED PARTICLES

DOEpatents

Post, R.F.; Coensgen, F.H.

1962-12-18

This patent relates to a device for materially increasing the energy and density of a plasma to produce conditions commensurate with the establishment and promotion of controlled thermonuclear reactions. To this end the device employs three successive stages of magnetic compression, each stage having magnetic mirrors to compress a plasma, the mirrors being moveable to transfer the plasma to successive stages for further compression. Accordingly, a plasma introduced to the first stage is increased in density and energy in stepwide fashion by virtue of the magnetic compression in the successive stages such that the plasma upon reaching the last stage is of extremely high energy and density commensurate the plasma particles undergoing thermonuclear reactions. The principal novelty of the device resides in the provision of a unidirectional magnetic field which increases in stepwise fashion in coaxially communicating compression chambers of progressively decreasing lengths and diameters. Pulsed magnetic fields are superimposed upon the undirectional field and are manipulated to establish resultant magnetic compression fields which increase in intensity and progressively move, with respect to time, through the compression chambers in the direction of the smallest one thereof. The resultant field in the last compression chamber is hence of relatively high intensity, and the density and energy of the plasma confined therein are correspondingly high. (AEC)

Mechanical and electrical properties of low temperature phase MnBi

DOE PAGES

Jiang, Xiujuan; Roosendaal, Timothy; Lu, Xiaochuan; ...

2016-01-21

The low temperature phase (LTP) MnBi is a promising rare-earth-free permanent magnet material due to its high intrinsic coercivity and its large positive temperature coefficient. While scientists are making progress on fabricating bulk MnBi magnets, engineers have started to consider MnBi magnet for motor applications. In addition to the magnetic properties, there are other physical properties that could significantly affect a motor design. Here, we report the results of our investigation on the mechanical and electrical properties of bulk LTP MnBi and their dependence on temperature. We found at room temperature the sintered MnBi magnet fractures when the compression stressmore » exceeds 193 MPa; and its room temperature electric resistance is about 6.85 μΩ-m.« less

Dynamic nuclear magnetic resonance field sensing with part-per-trillion resolution

NASA Astrophysics Data System (ADS)

Gross, Simon; Barmet, Christoph; Dietrich, Benjamin E.; Brunner, David O.; Schmid, Thomas; Pruessmann, Klaas P.

2016-12-01

High-field magnets of up to tens of teslas in strength advance applications in physics, chemistry and the life sciences. However, progress in generating such high fields has not been matched by corresponding advances in magnetic field measurement. Based mostly on nuclear magnetic resonance, dynamic high-field magnetometry is currently limited to resolutions in the nanotesla range. Here we report a concerted approach involving tailored materials, magnetostatics and detection electronics to enhance the resolution of nuclear magnetic resonance sensing by three orders of magnitude. The relative sensitivity thus achieved amounts to 1 part per trillion (10-12). To exemplify this capability we demonstrate the direct detection and relaxometry of nuclear polarization and real-time recording of dynamic susceptibility effects related to human heart function. Enhanced high-field magnetometry will generally permit a fresh look at magnetic phenomena that scale with field strength. It also promises to facilitate the development and operation of high-field magnets.

Magnetization Dynamics of Amorphous Ribbons and Wires Studied by Inductance Spectroscopy

PubMed Central

Betancourt, Israel

2010-01-01

Inductance spectroscopy is a particular formulation variant of the well known complex impedance formalism typically used for the electric characterization of dielectric, ferroelectric, and piezoelectric materials. It has been successfully exploited as a versatile tool for characterization of the magnetization dynamics in amorphous ribbons and wires by means of simple experiments involving coils for sample holding and impedance analyzer equipment. This technique affords the resolution of the magnetization processes in soft magnetic materials, in terms of reversible deformation of pinned domain walls, domain wall displacements and spin rotation, for which characteristic parameters such as the alloy initial permeability and the relaxation frequencies, indicating the dispersion of each process, can be defined. Additionally, these parameters can be correlated with chemical composition variation, size effects and induced anisotropies, leading to a more physical insight for the understanding of the frequency dependent magnetic response of amorphous alloys, which is of prime interest for the development of novel applications in the field of telecommunication and sensing technologies. In this work, a brief overview, together with recent progress on the magnetization dynamics of amorphous ribbons, wires, microwires and biphase wires, is presented and discussed for the intermediate frequency interval between 10 Hz and 13 MHz. PMID:28879975

Aperiodic topological order in the domain configurations of functional materials

NASA Astrophysics Data System (ADS)

Huang, Fei-Ting; Cheong, Sang-Wook

2017-03-01

In numerous functional materials, such as steels, ferroelectrics and magnets, new functionalities can be achieved through the engineering of the domain structures, which are associated with the ordering of certain parameters within the material. The recent progress in technologies that enable imaging at atomic-scale spatial resolution has transformed our understanding of domain topology, revealing that, along with simple stripe-like or irregularly shaped domains, intriguing vortex-type topological domain configurations also exist. In this Review, we present a new classification scheme of 'Zm Zn domains with Zl vortices' for 2D macroscopic domain structures with m directional variants and n translational antiphases. This classification, together with the concepts of topological protection and topological charge conservation, can be applied to a wide range of materials, such as multiferroics, improper ferroelectrics, layered transition metal dichalcogenides and magnetic superconductors, as we discuss using selected examples. The resulting topological considerations provide a new basis for the understanding of the formation, kinetics, manipulation and property optimization of domains and domain boundaries in functional materials.

Superconducting accelerator magnet technology in the 21st century: A new paradigm on the horizon?

NASA Astrophysics Data System (ADS)

Gourlay, S. A.

2018-06-01

Superconducting magnets for accelerators were first suggested in the mid-60's and have since become one of the major components of modern particle colliders. Technological progress has been slow but steady for the last half-century, based primarily on Nb-Ti superconductor. That technology has reached its peak with the Large Hadron Collider (LHC). Despite the superior electromagnetic properties of Nb3Sn and adoption by early magnet pioneers, it is just now coming into use in accelerators though it has not yet reliably achieved fields close to the theoretical limit. The discovery of the High Temperature Superconductors (HTS) in the late '80's created tremendous excitement, but these materials, with tantalizing performance at high fields and temperatures, have not yet been successfully developed into accelerator magnet configurations. Thanks to relatively recent developments in both Bi-2212 and REBCO, and a more focused international effort on magnet development, the situation has changed dramatically. Early optimism has been replaced with a reality that could create a new paradigm in superconducting magnet technology. Using selected examples of magnet technology from the previous century to define the context, this paper will describe the possible innovations using HTS materials as the basis for a new paradigm.

Materials engineering, characterization, and applications of the organicbased magnet, V[TCNE

NASA Astrophysics Data System (ADS)

Harberts, Megan

Organic materials have advantageous properties such as low cost and mechanical flexibility that have made them attractive to complement traditional materials used in electronics and have led to commercial success, especially in organic light emitting diodes (OLEDs). Many rapidly advancing technologies incorporate magnetic materials, leading to the potential for creating analogous organic-based magnetic applications. The semiconducting ferrimagnet, vanadium tetracyanoethylene, V[TCNE]x˜2, exhibits room temperature magnetic ordering which makes it an attractive candidate. My research is focused on development of thin films of V[TCNE]x˜2 through advancement in growth, materials engineering, and applications. My thesis is broken up into two sections, the first which provides background and details of V[TCNE]x˜2 growth and characterization. The second section focuses on advances beyond V[TCNE]x˜2 film growth. The ordering of the chapters is for the ease of the reader, but encompasses work that I led and robust collaborations that I have participated in. V[TCNE]x˜2 films are deposited through a chemical vapor deposition process (CVD). My advancements to the growth process have led to higher quality films which have higher magnetic ordering temperatures, more magnetically homogenous samples, and extremely narrow ferromagnetic resonance (FMR) linewidths. Beyond improvements in film growth, materials engineering has created new materials and structures with properties to compliment thin film V[TCNE]x˜2. Though a robust collaboration with chemistry colleagues, modification of the molecule TCNE has led to the creation of new magnetic materials vanadium methyl tricyanoethylene carboxylate, V[MeTCEC]x and vanadium ethyl tricyanoethylene carboxylate, V[ETCEC]x. Additionally, I have lead a project to deposit V[TCNE]x˜2 on periodically patterned substrates leading to the formation of a 1-D array of V[TCNE]x˜2 nanowires. These arrays exhibit in-plane magnetic anisotropy, which is not observed in films of V[TCNE]x˜2. Additional collaborations have also made significant progress in addressing one of the challenges for incorporating V[TCNE]x˜2 into applications, which is the degradation of magnetic properties with exposure to oxygen. By working off of encapsulation technology which has been developed for OLEDs, we have shown that we can use a simple epoxy to extend the magnetic properties of V[TCNE]x˜2 films from an order of hours to one month in ambient conditions.

Light Responsive Polymer Membranes: A Review

PubMed Central

Nicoletta, Fiore Pasquale; Cupelli, Daniela; Formoso, Patrizia; De Filpo, Giovanni; Colella, Valentina; Gugliuzza, Annarosa

2012-01-01

In recent years, stimuli responsive materials have gained significant attention in membrane separation processes due to their ability to change specific properties in response to small external stimuli, such as light, pH, temperature, ionic strength, pressure, magnetic field, antigen, chemical composition, and so on. In this review, we briefly report recent progresses in light-driven materials and membranes. Photo-switching mechanisms, valved-membrane fabrication and light-driven properties are examined. Advances and perspectives of light responsive polymer membranes in biotechnology, chemistry and biology areas are discussed. PMID:24957966

Europium-based iron pnictides: a unique laboratory for magnetism, superconductivity and structural effects

NASA Astrophysics Data System (ADS)

Zapf, Sina; Dressel, Martin

2017-01-01

Despite decades of intense research, the origin of high-temperature superconductivity in cuprates and iron-based compounds is still a mystery. Magnetism and superconductivity are traditionally antagonistic phenomena; nevertheless, there is basically no doubt left that unconventional superconductivity is closely linked to magnetism. But this is not the whole story; recently, also structural effects related to the so-called nematic phase gained considerable attention. In order to obtain more information about this peculiar interplay, systematic material research is one of the most important attempts, revealing from time to time unexpected effects. Europium-based iron pnictides are the latest example of such a completely paradigmatic material, as they display not only spin-density-wave and superconducting ground states, but also local Eu2+ magnetism at a similar temperature scale. Here we review recent experimental progress in determining the complex phase diagrams of europium-based iron pnictides. The conclusions drawn from the observations reach far beyond these model systems. Thus, although europium-based iron pnictides are very peculiar, they provide a unique platform to study the common interplay of structural-nematic, magnetic and electronic effects in high-temperature superconductors.

Superparamagnetic enhancement of thermoelectric performance.

PubMed

Zhao, Wenyu; Liu, Zhiyuan; Sun, Zhigang; Zhang, Qingjie; Wei, Ping; Mu, Xin; Zhou, Hongyu; Li, Cuncheng; Ma, Shifang; He, Danqi; Ji, Pengxia; Zhu, Wanting; Nie, Xiaolei; Su, Xianli; Tang, Xinfeng; Shen, Baogen; Dong, Xiaoli; Yang, Jihui; Liu, Yong; Shi, Jing

2017-09-13

The ability to control chemical and physical structuring at the nanometre scale is important for developing high-performance thermoelectric materials. Progress in this area has been achieved mainly by enhancing phonon scattering and consequently decreasing the thermal conductivity of the lattice through the design of either interface structures at nanometre or mesoscopic length scales or multiscale hierarchical architectures. A nanostructuring approach that enables electron transport as well as phonon transport to be manipulated could potentially lead to further enhancements in thermoelectric performance. Here we show that by embedding nanoparticles of a soft magnetic material in a thermoelectric matrix we achieve dual control of phonon- and electron-transport properties. The properties of the nanoparticles-in particular, their superparamagnetic behaviour (in which the nanoparticles can be magnetized similarly to a paramagnet under an external magnetic field)-lead to three kinds of thermoelectromagnetic effect: charge transfer from the magnetic inclusions to the matrix; multiple scattering of electrons by superparamagnetic fluctuations; and enhanced phonon scattering as a result of both the magnetic fluctuations and the nanostructures themselves. We show that together these effects can effectively manipulate electron and phonon transport at nanometre and mesoscopic length scales and thereby improve the thermoelectric performance of the resulting nanocomposites.

Evaluation of superconducting wiggler designs and free-electron laser support: Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1990-10-12

This report consists of copies of previous progress reports, and copies of viewgraphs presented in a talk at Los Alamos. The report describes activities carried out as part of a project to evaluate the design and performance of a superconducting wiggler magnet design. It includes work on evaluating the appropriate materials for the magnet coils and poles, and stress evaluations for the design. It includes work on beam optics through the magnet, and design considerations to optimize extraction: work on the cryocooling system; weight minimization efforts; and design work on the vacuum liner for the magnet. A major concern inmore » all of this design work is heat loads which will be dissipated in different parts of the system during operation, as well as transient events.« less

Progression in structural, magnetic and electrical properties of La-doped group IV elements

NASA Astrophysics Data System (ADS)

Deepapriya, S.; Annie Vinosha, P.; Rodney, John D.; Jerome Das, S.

2018-04-01

Progression of group IV elements such as zinc ferrite (ZnFe2O4), cobalt ferrite (CoFe2O4) was synthesized by doping lanthanum (La), via adopting a facile co-precipitation method. Doping hefty rare earth ion in spinel structure can amend to the physical properties of the lattice, which can be used in the enhancement of magnetic and electrical properties of the as-synthesized nanomaterial, it is vital to metamorphose and optimize its micro structural and magnetic features. The structural properties of the samples was analysed by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), Transmission electron microscopy (TEM) and UV-visible spectral analysis (UV-vis) reveals the optical property and optical band gap. The magnetic properties were evaluated using a vibrating sample magnetometer (VSM), the presence of functional group was confirmed by FTIR. XRD analyses elucidates that the synthesized samples zinc and cobalt had a spinel structure. From TEM analyses the morphology and diameter of the particle was observed. The substituted rare earth ions in Zinc ferrite inhibit the grain growth of the materials in an efficient manner compared with that of the Cobalt ferrite.

Status and future perspective of applications of high temperature superconductors

NASA Astrophysics Data System (ADS)

Tanaka, Shoji

The material research on the high temperature superconductivity for the past ten years gave us sufficient information on the new phenomena of these new materials. It seems that new applications in a very wide range of industries are increasing rapidly. In this report three main topics of the applications are given ; [a] progress of the superconducting bulk materials and their applications to the flywheel electricity storage system and others, [b] progress in the development of superconducting tapes and their applications to power cables, the high field superconducting magnet for the SMES and for the pulling system of large silicon single crystal, and [c] development of new superconducting electronic devices (SFQ) and the possiblity of the application to next generation supercomputers. These examples show the great capability of the superconductivity technology and it is expected that the real superconductivity industry will take off around the year of 2005.

Controlling Emergent Ferromagnetism at Complex Oxide Interfaces

NASA Astrophysics Data System (ADS)

Grutter, Alexander

The emergence of complex magnetic ground states at ABO3 perovskite heterostructure interfaces is among the most promising routes towards highly tunable nanoscale materials for spintronic device applications. Despite recent progress, isolating and controlling the underlying mechanisms behind these emergent properties remains a highly challenging materials physics problems. In particular, generating and tuning ferromagnetism localized at the interface of two non-ferromagnetic materials is of fundamental and technological interest. An ideal model system in which to study such effects is the CaRuO3/CaMnO3 interface, where the constituent materials are paramagnetic and antiferromagnetic in the bulk, respectively. Due to small fractional charge transfer to the CaMnO3 (0.07 e-/Mn) from the CaRuO3, the interfacial Mn ions are in a canted antiferromagnetic state. The delicate balance between antiferromagnetic superexchange and ferromagnetic double exchange results in a magnetic ground state which is extremely sensitive to perturbations. We exploit this sensitivity to achieve control of the magnetic interface, tipping the balance between ferromagnetic and antiferromagnetic interactions through octahedral connectivity modification. Such connectivity effects are typically tightly confined to interfaces, but by targeting a purely interfacial emergent magnetic system, we achieve drastic alterations to the magnetic ground state. These results demonstrate the extreme sensitivity of the magnetic state to the magnitude of the charge transfer, suggesting the potential for direct electric field control. We achieve such electric field control through direct back gating of a CaRuO3/CaMnO3 bilayer. Thus, the CaRuO3/CaMnO3 system provides new insight into how charge transfer, interfacial symmetry, and electric fields may be used to control ferromagnetism at the atomic scale.

Progress Towards Left-Handed Electromagnetic Waves in Rare-Earth Doped Crystals

NASA Astrophysics Data System (ADS)

Brewer, Nicholas Riley

In 1968 Victor Veselago determined that a material with both a negative permittivity and negative permeability would have some extraordinary properties. The index of refraction of this material would be negative and light propagating inside would be 'left-handed'. This research went relatively unnoticed until the year 2000 when John Pendry discovered that a lens with an index of refraction of n = -1 could, in principle, have infinite resolution. Since 2000, research into negative index materials has exploded. The challenging part of this research is to get a material to respond to magnetic fields at optical frequencies. Artificially created metamaterials are able to achieve this and have been the focus of most negative index research. The long term goal of our project is to produce left-handed light in an atomic system. In order to do this, an atomic transition needs to be utilized that is magnetic dipole in character. Pure magnetic dipole transitions in the optical regime are more rare and fundamentally much weaker than the electric dipole transitions typically used in atomic physics experiments. They can be found, however, in the complex atomic structure of rare-earth elements. The 7F0 → 5D 1 transition in europium doped yttrium orthosilicate (Eu3+:Y 2SiO5) has a wavelength of 527.5 nm and is a pure magnetic dipole transition. We measured its dipole moment to be (0.063 +/- 0.005)mu B via Rabi oscillations, inferring a magnetization on the order of 10 -2 A/m. Demonstrating this large magnetic response at an optical frequency is a major first step in realizing left-handed light in atomic systems.

Dynamic nuclear magnetic resonance field sensing with part-per-trillion resolution

PubMed Central

Gross, Simon; Barmet, Christoph; Dietrich, Benjamin E.; Brunner, David O.; Schmid, Thomas; Pruessmann, Klaas P.

2016-01-01

High-field magnets of up to tens of teslas in strength advance applications in physics, chemistry and the life sciences. However, progress in generating such high fields has not been matched by corresponding advances in magnetic field measurement. Based mostly on nuclear magnetic resonance, dynamic high-field magnetometry is currently limited to resolutions in the nanotesla range. Here we report a concerted approach involving tailored materials, magnetostatics and detection electronics to enhance the resolution of nuclear magnetic resonance sensing by three orders of magnitude. The relative sensitivity thus achieved amounts to 1 part per trillion (10−12). To exemplify this capability we demonstrate the direct detection and relaxometry of nuclear polarization and real-time recording of dynamic susceptibility effects related to human heart function. Enhanced high-field magnetometry will generally permit a fresh look at magnetic phenomena that scale with field strength. It also promises to facilitate the development and operation of high-field magnets. PMID:27910860

Neutron-scattering-based evidence for interacting magnetic excitons in LaCo O 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

El-Khatib, S.; Phelan, D.; Barker, J. G.

Recent progress with the thermally-driven spin-state crossover in LaCoO3 has made it increasingly apparent that the nominally non-magnetic low spin ground state of this material actually hosts novel defect-'based magnetism. This is investigated here via a small-angle neutron scattering (SANS) study of LaCoO3-s crystals. The results provide: (i) the surprising finding that the spin-state crossover is clearly reflected in SANS via quasielastic/inelastic scattering from paramagnetic spin fluctuations/excitations, and (ii) evidence for the formation, likely around oxygen defects, of local entities known as magnetic excitons. The latter generate distinct magnetic scattering below 60 K, providing valuable quantitative information on exciton densitiesmore » and interactions. Potential relevance to the unexpected ferromagnetism recently discovered in epitaxial LaCoO3 films is discussed.« less

Thermal magnetic field noise limits resolution in transmission electron microscopy.

PubMed

Uhlemann, Stephan; Müller, Heiko; Hartel, Peter; Zach, Joachim; Haider, Max

2013-07-26

The resolving power of an electron microscope is determined by the optics and the stability of the instrument. Recently, progress has been obtained towards subångström resolution at beam energies of 80 kV and below but a discrepancy between the expected and achieved instrumental information limit has been observed. Here we show that magnetic field noise from thermally driven currents in the conductive parts of the instrument is the root cause for this hitherto unexplained decoherence phenomenon. We demonstrate that the deleterious effect depends on temperature and at least weakly on the type of material.

Noise Modeling From Conductive Shields Using Kirchhoff Equations.

PubMed

Sandin, Henrik J; Volegov, Petr L; Espy, Michelle A; Matlashov, Andrei N; Savukov, Igor M; Schultz, Larry J

2010-10-09

Progress in the development of high-sensitivity magnetic-field measurements has stimulated interest in understanding the magnetic noise of conductive materials, especially of magnetic shields based on high-permeability materials and/or high-conductivity materials. For example, SQUIDs and atomic magnetometers have been used in many experiments with mu-metal shields, and additionally SQUID systems frequently have radio frequency shielding based on thin conductive materials. Typical existing approaches to modeling noise only work with simple shield and sensor geometries while common experimental setups today consist of multiple sensor systems with complex shield geometries. With complex sensor arrays used in, for example, MEG and Ultra Low Field MRI studies, knowledge of the noise correlation between sensors is as important as knowledge of the noise itself. This is crucial for incorporating efficient noise cancelation schemes for the system. We developed an approach that allows us to calculate the Johnson noise for arbitrary shaped shields and multiple sensor systems. The approach is efficient enough to be able to run on a single PC system and return results on a minute scale. With a multiple sensor system our approach calculates not only the noise for each sensor but also the noise correlation matrix between sensors. Here we will show how the algorithm can be implemented.

Materials process and applications of single grain (RE)-Ba-Cu-O bulk high-temperature superconductors

NASA Astrophysics Data System (ADS)

Li, Beizhan; Zhou, Difan; Xu, Kun; Hara, Shogo; Tsuzuki, Keita; Miki, Motohiro; Felder, Brice; Deng, Zigang; Izumi, Mitsuru

2012-11-01

This paper reviews recent advances in the melt process of (RE)-Ba-Cu-O [(RE)BCO, where RE represents a rare earth element] single grain high-temperature superconductors (HTSs), bulks and its applications. The efforts on the improvement of the magnetic flux pinning with employing the top-seeded melt-growth process technique and using a seeded infiltration and growth process are discussed. Which including various chemical doping strategies and controlled pushing effect based on the peritectic reaction of (RE)BCO. The typical experiment results, such as the largest single domain bulk, the clear TEM observations and the significant critical current density, are summarized together with the magnetization techniques. Finally, we highlight the recent prominent progress of HTS bulk applications, including Maglev, flywheel, power device, magnetic drug delivery system and magnetic resonance devices.

Rock magnetic and geochemical analyses of surface sediment characteristics in deep ocean environments: A case study across the Ryukyu Trench

NASA Astrophysics Data System (ADS)

Kawamura, N.; Kawamura, K.; Ishikawa, N.

2008-03-01

Magnetic minerals in marine sediments are often dissolved or formed with burial depth, thereby masking the primary natural remanent magnetization and paleoclimate signals. In order to clarify the present sedimentary environment and the progressive changes with burial depth in the magnetic properties, we studied seven cores collected from the Ryukyu Trench, southwest Japan. Magnetic properties, organic geochemistry, and interstitial water chemistry of seven cores are described. Bottom water conditions at the landward slope, trench floor, and seaward slope are relatively suboxic, anoxic, and oxic, respectively. The grain size of the sediments become gradually finer with the distance from Okinawa Island and finer with increasing water depth. The magnetic carriers in the sediments are predominantly magnetite and maghemized magnetite, with minor amounts of hematite. In the topmost sediments from the landward slope, magnetic minerals are diluted by terrigenous materials and microfossils. The downcore variations in magnetic properties and geochemical data provided evidence for the dissolution of fine-grained magnetite with burial depth under an anoxic condition.

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

NASA Astrophysics Data System (ADS)

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

2014-05-01

A detailed field study on a small test site of agricultural land situated in loess region in Southern Moravia (Czech Republic) and subsequent laboratory analyses have been carried out in order to test the applicability of magnetic methods for the estimation of soil erosion. Chernozem, the original dominant soil unit in the wider area, is nowadays progressively transformed into different soil units along with intensive soil erosion. As a result, an extremely diversified soil cover structure has resulted from the erosion. The site was characterized by a flat upper part while the middle part, formed by a substantive side valley, is steeper (up to 15°). We carried out field measurements of magnetic susceptibility on a regular grid, resulting in 101 data points. The bulk soil material for laboratory investigation was gathered from all the grid points. We found a strong correlation between the volume magnetic susceptibility (field measurement) and mass specific magnetic susceptibility measured in the laboratory (R2 = 0.80). Values of the magnetic susceptibility are spatially distributed depending on the terrain. Higher values were measured in the flat upper part (where the original top horizon remained). The lowest values of magnetic susceptibility were obtained on the steep valley sides. Here the original topsoil was eroded and mixed by tillage with the soil substrate (loess). The soil profile that was unaffected by erosion was investigated in detail. The vertical distribution of magnetic susceptibility along this "virgin" profile was measured in laboratory on the samples from layers along the whole profile with 2-cm spacing. The undisturbed profile shows several soil horizons. Horizons Ac and A show a slight increase in magnetic susceptibility up to a depth of about 70 cm. Horizon A/Ck is characterized by a decrease in susceptibility, and the underlying C horizon (h > 103 cm) has a very low value of magnetic susceptibility. The differences between the values of susceptibility in the undisturbed soil profile and the magnetic signal after uniform mixing the soil material as a result of tillage and erosion are fundamental for the estimation of soil loss in the studied test field. Using the uneroded profile from the studied locality as a basis for examining the changes in cultivated soils, tillage homogenization model can be applied to predict changes in the surface soil magnetism with progressive soil erosion. The model is very well applicable at the studied site. Acknowledgement: This study was supported by NAZV Agency of the Ministry of Agriculture of the Czech Republic through grant No QJ1230319

Electrical detection of magnetization dynamics via spin rectification effects

NASA Astrophysics Data System (ADS)

Harder, Michael; Gui, Yongsheng; Hu, Can-Ming

2016-11-01

The purpose of this article is to review the current status of a frontier in dynamic spintronics and contemporary magnetism, in which much progress has been made in the past decade, based on the creation of a variety of micro and nanostructured devices that enable electrical detection of magnetization dynamics. The primary focus is on the physics of spin rectification effects, which are well suited for studying magnetization dynamics and spin transport in a variety of magnetic materials and spintronic devices. Intended to be intelligible to a broad audience, the paper begins with a pedagogical introduction, comparing the methods of electrical detection of charge and spin dynamics in semiconductors and magnetic materials respectively. After that it provides a comprehensive account of the theoretical study of both the angular dependence and line shape of electrically detected ferromagnetic resonance (FMR), which is summarized in a handbook format easy to be used for analysing experimental data. We then review and examine the similarity and differences of various spin rectification effects found in ferromagnetic films, magnetic bilayers and magnetic tunnel junctions, including a discussion of how to properly distinguish spin rectification from the spin pumping/inverse spin Hall effect generated voltage. After this we review the broad applications of rectification effects for studying spin waves, nonlinear dynamics, domain wall dynamics, spin current, and microwave imaging. We also discuss spin rectification in ferromagnetic semiconductors. The paper concludes with both historical and future perspectives, by summarizing and comparing three generations of FMR spectroscopy which have been developed for studying magnetization dynamics.

Analysis of soft magnetic materials by electron backscatter diffraction as a powerful tool

NASA Astrophysics Data System (ADS)

Schuller, David; Hohs, Dominic; Loeffler, Ralf; Bernthaler, Timo; Goll, Dagmar; Schneider, Gerhard

2018-04-01

The current work demonstrates that electron backscatter diffraction (EBSD) is a powerful and versatile characterization technique for investigating soft magnetic materials. The properties of soft magnets, e.g., magnetic losses strongly depend on the materials chemical composition and microstructure, including grain size and shape, texture, degree of plastic deformation and elastic strain. In electrical sheet stacks for e-motor applications, the quality of the machined edges/surfaces of each individual sheet is of special interest. Using EBSD, the influence of the punching process on the microstructure at the cutting edge is quantitatively assessed by evaluating the crystallographic misorientation distribution of the deformed grains. Using an industrial punching process, the maximum affected deformation depth is determined to be 200 - 300 μm. In the case of laser cutting, the affected deformation depth is determined to be approximately zero. Reliability and detection limits of the developed EBSD approach are evaluated on non-affected sample regions and model samples containing different indentation test bodies. A second application case is the investigation of the recrystallization process during the annealing step of soft magnetic composites (SMC) toroids produced by powder metallurgy as a function of compaction pressure, annealing parameters and powder particle size. With increasing pressure and temperature, the recrystallized area fraction (e.g., grains with crystallographic misorientations < 3°) increases from 71 % (200 MPa, 800°C) to 90% (800 MPa, 800°C). Recrystallization of the compacted powder material starts at the particle boundaries or areas with existing plastic deformation. The progress of recrystallization is visualized as a function of time and of different particle to grain size distributions. Here, large particles with coarse internal grain structures show a favorable recrystallization behavior which results in large bulk permeability of up to 600 - 700 and lower amount of residual misorientations (>3°).

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

NASA Astrophysics Data System (ADS)

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

2014-12-01

A detailed field study on a small test site of agricultural land situated in loess region in Southern Moravia (Czech Republic) and laboratory analyses were carried out in order to test the applicability of magnetic methods in assessing soil erosion. Haplic Chernozem, the original dominant soil unit in the area, is nowadays progressively transformed into different soil units along with intense soil erosion. As a result, an extremely diversified soil cover structure has developed due to the erosion. The site was characterized by a flat upper part while the middle part, formed by a substantive side valley, is steeper. We carried out field measurements of magnetic susceptibility on a regular grid, resulting in 101 data points. The bulk soil material for laboratory investigation was gathered from all the grid points. Values of the magnetic susceptibility are spatially distributed depending on the terrain. Higher values were measured in the flat upper part (where the original top horizon remained). The lowest values of were obtained on the steep valley sides. Here the original topsoil was eroded and mixed by tillage with the soil substrate (loess). A soil profile unaffected by erosion was investigated in detail. The vertical distribution of magnetic susceptibility along this "virgin" profile was measured in laboratory on the samples collected with 2-cm spacing. The undisturbed profile shows several soil horizons. Horizons Ac and A show a slight increase in magnetic susceptibility up to a depth of about 70 cm. Horizon A/Ck is characterized by a decrease in susceptibility, and the underlying C horizon (h > 103 cm) has a very low value of magnetic susceptibility. The differences between the values of susceptibility in the undisturbed soil profile and the magnetic signal after uniform mixing the soil material as a result of tillage and erosion are fundamental for the estimation of soil loss in the studied test field. Using the uneroded profile from the studied locality as a basis for examining the changes in cultivated soils, tillage homogenization model can be applied to predict changes in the surface soil magnetism with progressive soil erosion. The model is very well applicable at the studied site. Acknowledgement: This study was supported by NAZV Agency of the Ministry of Agriculture of the Czech Republic through grant No QJ1230319.

NiFe nanoparticles: a soft magnetic material?

PubMed

Margeat, Olivier; Ciuculescu, Diana; Lecante, Pierre; Respaud, Marc; Amiens, Catherine; Chaudret, Bruno

2007-03-01

Polytetrahedral NiFe nanoparticles with diameters of (2.8+/-0.3) nm have been obtained by hydrogenation of Ni[(COD)(2)] (COD=1,5-cyclooctadiene) and Fe[{N(SiMe(3))(2)}(2)] at 150 degrees C using stearic acid and hexadecylamine as stabilizing ligands. The nanoparticles are superparamagnetic at room temperature and display a blocking temperature of 17.6 K. Their anisotropy (2.7x10(5)J m(-3)) is determined to be more than two orders of magnitude higher than that of the bulk NiFe alloy (10(3)J m(-3)) and is close to that determined for Fe nanoparticles of the same size. Still, they display a magnetization of (1.69+/-0.05) mu(B) per metallic atom, identical to that of the bulk NiFe alloy. Combining the results from X-ray absorption and Mössbauer studies, we evidence a progressive enrichment in iron atoms from the core to the surface of the nanoparticles. These results are discussed in relation to both size and chemical effects. They show the main role played by the enriched Fe surface on the magnetic properties and address the feasibility of soft magnetic materials at the nanoscale.

Progress in Mirror-Based Fusion Neutron Source Development.

PubMed

Anikeev, A V; Bagryansky, P A; Beklemishev, A D; Ivanov, A A; Kolesnikov, E Yu; Korzhavina, M S; Korobeinikova, O A; Lizunov, A A; Maximov, V V; Murakhtin, S V; Pinzhenin, E I; Prikhodko, V V; Soldatkina, E I; Solomakhin, A L; Tsidulko, Yu A; Yakovlev, D V; Yurov, D V

2015-12-04

The Budker Institute of Nuclear Physics in worldwide collaboration has developed a project of a 14 MeV neutron source for fusion material studies and other applications. The projected neutron source of the plasma type is based on the gas dynamic trap (GDT), which is a special magnetic mirror system for plasma confinement. Essential progress in plasma parameters has been achieved in recent experiments at the GDT facility in the Budker Institute, which is a hydrogen (deuterium) prototype of the source. Stable confinement of hot-ion plasmas with the relative pressure exceeding 0.5 was demonstrated. The electron temperature was increased up to 0.9 keV in the regime with additional electron cyclotron resonance heating (ECRH) of a moderate power. These parameters are the record for axisymmetric open mirror traps. These achievements elevate the projects of a GDT-based neutron source on a higher level of competitive ability and make it possible to construct a source with parameters suitable for materials testing today. The paper presents the progress in experimental studies and numerical simulations of the mirror-based fusion neutron source and its possible applications including a fusion material test facility and a fusion-fission hybrid system.

Development of new oganic-based magments for spintronics

NASA Astrophysics Data System (ADS)

Lu, Yu

Organic-based magnets are an emerging research area. The chemical tailorability, all benefits of organic materials as well as potential use in organic spintronics make them an important supplement to traditional metal/metal oxide magnets. This dissertation focused on development of new organic-based magnets, which is composed of three parts. In the first part, a new high Curie temperature (Tc ˜ 145 K) organic-based magnet with composition of vanadium ethyl tricyanoethlyenecarboxylate (V[ETCEC]1.3•0.3 CH2Cl2) is prepared via a reaction of V(CO)6 and ETCEC in CH2Cl2. Temperature-, field-, and frequency-dependent measurements of the magnetization reveal complex magnetic behavior with a magnetic transition into a more disordered state. Since ethyl tricyanoethlyenecarboxylate (ETCEC) holds the structure similarity with tetracyanoethylene (TCNE) and methyl tricyanoethylenecarboxylate (MeTCEC), the comparison is made among these materials, which indicates the effects of steric hindrance and electron negativity on magnetic properties. Application of the random anisotropy model (RMA) shows that this disordered state is different from the correlated spin glass (CSG) phase observed in analogous organic-based magnets V[MeTCEC]x and V[TCNE]x synthesized in CH2Cl2. This suggests that V[ETCEC]x is less disordered than its analogues, which can be attributed to the slower reaction rate. In the second part, I will present the first successful attempt at ligand modification in chemical vapor deposition (CVD) prepared thin film by replacing a single cyano group on TCNE with an ester on ETCEC and MeTCEC. The resulting films have magnetic ordering temperature of ˜175 K and ˜300 K respectively, providing the first viable complement to V[TCNE]2 and opening the door to an entire class of all-organic magnetic heterostructures. These heterostructures will retain the central benefits demonstrated in other areas of organic electronics such as low cost, low deposition temperature and conformal deposition, while incorporating key magnetic based functionality such as non-volatile memory, magnetic sensing and applications in high frequency magnetoelectronics. The structures, magnetic and electronic properties of these materials are characterized by a combination of various instruments. The last part of this dissertation will focus on the progress that have been made during my PhD study toward the application of organic-based magnets, including encapsulation of these materials to protect them from degradation, optimization of growth conditions to achieve high quality films with super-narrow ferromagentic resonance (FMR) signal (˜1 G) and application of thin film V[TCNE]x as a spin injector/detector in spin-valves.

Magnetic nanoparticles: In vivo cancer diagnosis and therapy.

PubMed

Lima-Tenório, Michele K; Pineda, Edgardo A Gómez; Ahmad, Nasir M; Fessi, Hatem; Elaissari, Abdelhamid

2015-09-30

Recently, significant research efforts have been devoted to the finding of efficient approaches in order to reduce the side effects of traditional cancer therapy and diagnosis. In this context, magnetic nanoparticles have attracted much attention because of their unique physical properties, magnetic susceptibility, biocompatibility, stability and many more relevant characteristics. Particularly, magnetic nanoparticles for in vivo biomedical applications need to fulfill special criteria with respect to size, size distribution, surface charge, biodegradability or bio-eliminability and optionally bear well selected ligands for specific targeting. In this context, many routes have been developed to synthesize these materials, and tune their functionalities through intriguing techniques including functionalization, coating and encapsulation strategies. In this review article, the use of magnetic nanoparticles for cancer therapy and diagnosis is evaluated addressing potential applications in MRI, drug delivery, hyperthermia, theranostics and several other domains. In view of potential biomedical applications of magnetic nanoparticles, the review focuses on the most recent progress made with respect to synthetic routes to produce magnetic nanoparticles and their salient accomplishments for in vivo cancer diagnosis and therapy. Copyright © 2015 Elsevier B.V. All rights reserved.

Fusion energy division annual progress report, period ending December 31, 1980

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1981-11-01

The ORNL Program encompasses most aspects of magnetic fusion research including research on two magnetic confinement programs (tokamaks and ELMO bumpy tori); the development of the essential technologies for plasma heating, fueling, superconducting magnets, and materials; the development of diagnostics; the development of atomic physics and radiation effect data bases; the assessment of the environmental impact of magnetic fusion; the physics and engineering of present-generation devices; and the design of future devices. The integration of all of these activities into one program is a major factor in the success of each activity. An excellent example of this integration is themore » extremely successful application of neutral injection heating systems developed at ORNL to tokamaks both in the Fusion Energy Division and at Princeton Plasma Physics Laboratory (PPPL). The goal of the ORNL Fusion Program is to maintain this balance between plasma confinement, technology, and engineering activities.« less

PREFACE: Soft Magnetic Materials 8

NASA Astrophysics Data System (ADS)

Pfützner, H.

1988-01-01

The Conference "Soft Magnetic Materials 8" was held from 1 to 4 September 1987 at the Congress Centre Badgastein, Austria. It was organized by the Division of Bioelectricity and Magnetism and by the Institute of Applied and Technical Physics of the University of Technology, Vienna. The Conference was the eighth in the bi-annual series which commenced in Turin, Italy. It was attended by about 130 scientists from universities and industrial companies from 19 countries. The theme of the Conference was the recent progress in industrial applications and developments of soft magnetic alloys including magnetic measurements and field computation problems as well as fundamental aspects. In five sessions, 13 invited papers were presented in oral form. In addition, the program of poster sessions included 122 contributed papers. Regrettably, some of them were not presented when authors (especially from Eastern European countries as well as from China) were unable to be present. A clear emphasis of papers was laid on characteristics and applications of amorphous materials. As confirmed by the delegates, the spacious Congress Centre—well aerated by the near-by waterfall—provided an effective environment for informal discussions. The Conference Dinner as well as the Mountain Lodge Evening were utilized for general communications in an intensive form. However, a slight mishap of this Conference should not be concealed: Due to a thunder storm, one delegate spent a long frosty night on a rock peak of Badgasteins mountains. Still, next day he presented his excellent paper in top condition. The next Conference, SMM9, is planned to be held in El Escorial, Spain, in 1989.

Improper ferroelectric polarization in a perovskite driven by intersite charge transfer and ordering

NASA Astrophysics Data System (ADS)

Chen, Wei-Tin; Wang, Chin-Wei; Wu, Hung-Cheng; Chou, Fang-Cheng; Yang, Hung-Duen; Simonov, Arkadiy; Senn, M. S.

2018-04-01

It is of great interest to design and make materials in which ferroelectric polarization is coupled to other order parameters such as lattice, magnetic, and electronic instabilities. Such materials will be invaluable in next-generation data storage devices. Recently, remarkable progress has been made in understanding improper ferroelectric coupling mechanisms that arise from lattice and magnetic instabilities. However, although theoretically predicted, a compact lattice coupling between electronic and ferroelectric (polar) instabilities has yet to be realized. Here we report detailed crystallographic studies of a perovskite HgAMn3A'Mn4BO12 that is found to exhibit a polar ground state on account of such couplings that arise from charge and orbital ordering on both the A'- and B-sites, which are themselves driven by a highly unusual MnA '-MnB intersite charge transfer. The inherent coupling of polar, charge, orbital, and hence magnetic degrees of freedom make this a system of great fundamental interest, and demonstrating ferroelectric switching in this and a host of recently reported hybrid improper ferroelectrics remains a substantial challenge.

Biofunctionalized magnetic-vortex microdiscs for targeted cancer-cell destruction

PubMed Central

Kim, Dong-Hyun; Rozhkova, Elena A.; Ulasov, Ilya V.; Bader, Samuel D.; Rajh, Tijana; Lesniak, Maciej S.; Novosad, Valentyn

2009-01-01

Nanomagnetic materials offer exciting avenues for probing cell mechanics and activating mechanosensitive ion channels, as well as for advancing cancer therapies. Most experimental works so far have used superparamagnetic materials. This report describes a first approach based on interfacing cells with lithographically defined microdiscs that possess a spin-vortex ground state. When an alternating magnetic field is applied the microdisc vortices shift, creating an oscillation, which transmits a mechanical force to the cell. Because reduced sensitivity of cancer cells toward apoptosis leads to inappropriate cell survival and malignant progression, selective induction of apoptosis is of great importance for the anticancer therapeutic strategies. We show that the spin-vortex-mediated stimulus creates two dramatic effects: compromised integrity of the cellular membrane, and initiation of programmed cell death. A low-frequency field of a few tens of hertz applied for only ten minutes was sufficient to achieve ~90% cancer-cell destruction in vitro. PMID:19946279

Progress on the Development of the hPIC Particle-in-Cell Code

NASA Astrophysics Data System (ADS)

Dart, Cameron; Hayes, Alyssa; Khaziev, Rinat; Marcinko, Stephen; Curreli, Davide; Laboratory of Computational Plasma Physics Team

2017-10-01

Advancements were made in the development of the kinetic-kinetic electrostatic Particle-in-Cell code, hPIC, designed for large-scale simulation of the Plasma-Material Interface. hPIC achieved a weak scaling efficiency of 87% using the Algebraic Multigrid Solver BoomerAMG from the PETSc library on more than 64,000 cores of the Blue Waters supercomputer at the University of Illinois at Urbana-Champaign. The code successfully simulates two-stream instability and a volume of plasma over several square centimeters of surface extending out to the presheath in kinetic-kinetic mode. Results from a parametric study of the plasma sheath in strongly magnetized conditions will be presented, as well as a detailed analysis of the plasma sheath structure at grazing magnetic angles. The distribution function and its moments will be reported for plasma species in the simulation domain and at the material surface for plasma sheath simulations. Membership Pending.

Tunable electronic and magnetic properties of two-dimensional materials and their one-dimensional derivatives.

PubMed

Zhang, Zhuhua; Liu, Xiaofei; Yu, Jin; Hang, Yang; Li, Yao; Guo, Yufeng; Xu, Ying; Sun, Xu; Zhou, Jianxin; Guo, Wanlin

2016-01-01

Low-dimensional materials exhibit many exceptional properties and functionalities which can be efficiently tuned by externally applied force or fields. Here we review the current status of research on tuning the electronic and magnetic properties of low-dimensional carbon, boron nitride, metal-dichalcogenides, phosphorene nanomaterials by applied engineering strain, external electric field and interaction with substrates, etc, with particular focus on the progress of computational methods and studies. We highlight the similarities and differences of the property modulation among one- and two-dimensional nanomaterials. Recent breakthroughs in experimental demonstration of the tunable functionalities in typical nanostructures are also presented. Finally, prospective and challenges for applying the tunable properties into functional devices are discussed. WIREs Comput Mol Sci 2016, 6:324-350. doi: 10.1002/wcms.1251 For further resources related to this article, please visit the WIREs website. The authors have declared no conflicts of interest for this article.

Year 3 Magnet Schools Assistance Program Annual Progress Report, 2009-10. E&R Report No. 10.09

ERIC Educational Resources Information Center

Brasfield, Jon; Cárdenas, Virginia

2010-01-01

The three Magnet Schools Assistance Program (MSAP) schools: East Garner International Baccalaureate Magnet Middle School (EGMMS), Garner International Baccalaureate Magnet High School (GMHS), and Southeast Raleigh Leadership and Technology Magnet High School (SRMHS) have shown progress on MSAP performance measures during the 3rd year of the grant.…

Magnetic-mediated hyperthermia for cancer treatment: Research progress and clinical trials

NASA Astrophysics Data System (ADS)

Zhao, Ling-Yun; Liu, Jia-Yi; Ouyang, Wei-Wei; Li, Dan-Ye; Li, Li; Li, Li-Ya; Tang, Jin-Tian

2013-10-01

Research progress and frontiers of magnetic-mediated hyperthermia (MMH) are presented, along with clinical trials in Germany, the US, Japan, and China. Special attention is focused on MMH mediated by magnetic nanoparticles, and multifunctional magnetic devices for cancer multimodality treatment are also introduced.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mccall, Scott K.; Kuntz, Joshua D.

A method of making a bulk exchange spring magnet by providing a magnetically soft material, providing a hard magnetic material, and producing a composite of said magnetically soft material and said hard magnetic material to make the bulk exchange spring magnet. The step of producing a composite of magnetically soft material and hard magnetic material is accomplished by electrophoretic deposition of the magnetically soft material and the hard magnetic material to make the bulk exchange spring magnet.

Theoretical Studies of Magnetic Systems. Final Report, August 1, 1994 - November 30, 1997

DOE R&D Accomplishments Database

Gor`kov, L. P.; Novotny, M. A.; Schrieffer, J. R.

1997-01-01

During the grant period the authors have studied five areas of research: (1) low dimensional ferrimagnets; (2) lattice effects in the mixed valence problem; (3) spin compensation in the one dimensional Kondo lattice; (4) the interaction of quasi particles in short coherence length superconductors; and (5) novel effects in angle resolved photoemission spectra from nearly antiferromagnetic materials. Progress in each area is summarized.

Review of progress in quantitative NDE

NASA Astrophysics Data System (ADS)

s of 386 papers and plenary presentations are included. The plenary sessions are related to the national technology initiative. The other sessions covered the following NDE topics: corrosion, electromagnetic arrays, elastic wave scattering and backscattering/noise, civil structures, material properties, holography, shearography, UT wave propagation, eddy currents, coatings, signal processing, radiography, computed tomography, EM imaging, adhesive bonds, NMR, laser ultrasonics, composites, thermal techniques, magnetic measurements, nonlinear acoustics, interface modeling and characterization, UT transducers, new techniques, joined materials, probes and systems, fatigue cracks and fracture, imaging and sizing, NDE in engineering and process control, acoustics of cracks, and sensors. An author index is included.

A review of magnetic resonance imaging compatible manipulators in surgery.

PubMed

Elhawary, H; Zivanovic, A; Davies, B; Lampérth, M

2006-04-01

Developments in magnetic resonance imaging (MRI), coupled with parallel progress in the field of computer-assisted surgery, mean that an ideal environment has been created for the development of MRI-compatible robotic systems and manipulators, capable of enhancing many types of surgical procedure. However, MRI does impose severe restrictions on mechatronic devices to be used in or around the scanners. In this article a review of the developments in the field of MRI-compatible surgical manipulators over the last decade is presented. The manipulators developed make use of different methods of actuation, but they can be reduced to four main groups: actuation transmitted through hydraulics, pneumatic actuators, ultrasonic motors based on the piezoceramic principle and remote manual actuation. Progress has been made concerning material selection, position sensing, and different actuation techniques, and design strategies have been implemented to overcome the multiple restrictions imposed by the MRI environment. Most systems lack the clinical validation needed to continue on to commercial products.

Progress on PEEM3 -- An Aberration Corrected X-Ray Photoemission Electron Microscope at the ALS

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacDowell, A. A.; Feng, J.; DeMello, A.

2007-01-19

A new ultrahigh-resolution photoemission electron microscope called PEEM3 is being developed and built at the Advanced Light Source (ALS). An electron mirror combined with a much-simplified magnetic dipole separator is to be used to provide simultaneous correction of spherical and chromatic aberrations. It is installed on an elliptically polarized undulator (EPU) beamline, and will be operated with very high spatial resolution and high flux to study the composition, structure, electric and magnetic properties of complex materials. The instrument has been designed and is described. The instrumental hardware is being deployed in 2 phases. The first phase is the deployment ofmore » a standard PEEM type microscope consisting of the standard linear array of electrostatic electron lenses. The second phase will be the installation of the aberration corrected upgrade to improve resolution and throughput. This paper describes progress as the instrument enters the commissioning part of the first phase.« less

Progress on PEEM3 - An Aberration Corrected X-Ray PhotoemissionElectron Microscope at the ALS

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacDowell, Alastair A.; Feng, J.; DeMello, A.

2006-05-20

A new ultrahigh-resolution photoemission electron microscope called PEEM3 is being developed and built at the Advanced Light Source (ALS). An electron mirror combined with a much-simplified magnetic dipole separator is to be used to provide simultaneous correction of spherical and chromatic aberrations. It is installed on an elliptically polarized undulator (EPU) beamline, and will be operated with very high spatial resolution and high flux to study the composition, structure, electric and magnetic properties of complex materials. The instrument has been designed and is described. The instrumental hardware is being deployed in 2 phases. The first phase is the deployment ofmore » a standard PEEM type microscope consisting of the standard linear array of electrostatic electron lenses. The second phase will be the installation of the aberration corrected upgrade to improve resolution and throughput. This paper describes progress as the instrument enters the commissioning part of the first phase.« less

Development of low temperature and high magnetic field X-ray diffraction facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shahee, Aga; Sharma, Shivani; Singh, K.

2015-06-24

The current progress of materials science regarding multifunctional materials (MFM) has put forward the challenges to understand the microscopic origin of their properties. Most of such MFMs have magneto-elastic correlations. To investigate the underlying mechanism it is therefore essential to investigate the structural properties in the presence of magnetic field. Keeping this in view low temperature and high magnetic field (LTHM) powder x-ray diffraction (XRD), a unique state-of-art facility in the country has been developed at CSR Indore. This setup works on symmetric Bragg Brentano geometry using a parallel incident x-ray beam from a rotating anode source working at 17more » kW. Using this one can do structural studies at non-ambient conditions i.e. at low- temperatures (2-300 K) and high magnetic field (+8 to −8 T). The available scattering angle ranges from 5° to 115° 2θ with a resolution better than 0.1°. The proper functioning of the setup has been checked using Si sample. The effect of magnetic field on the structural properties has been demonstrated on Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3} sample. Clear effect of field induced phase transition has been observed. Moreover, the effect of zero field cooled and field cooled conditions is also observed.« less

Upconverting and NIR emitting rare earth based nanostructures for NIR-bioimaging

NASA Astrophysics Data System (ADS)

Hemmer, Eva; Venkatachalam, Nallusamy; Hyodo, Hiroshi; Hattori, Akito; Ebina, Yoshie; Kishimoto, Hidehiro; Soga, Kohei

2013-11-01

In recent years, significant progress was achieved in the field of nanomedicine and bioimaging, but the development of new biomarkers for reliable detection of diseases at an early stage, molecular imaging, targeting and therapy remains crucial. The disadvantages of commonly used organic dyes include photobleaching, autofluorescence, phototoxicity and scattering when UV (ultraviolet) or visible light is used for excitation. The limited penetration depth of the excitation light and the visible emission into and from the biological tissue is a further drawback with regard to in vivo bioimaging. Lanthanide containing inorganic nanostructures emitting in the near-infrared (NIR) range under NIR excitation may overcome those problems. Due to the outstanding optical and magnetic properties of lanthanide ions (Ln3+), nanoscopic host materials doped with Ln3+, e.g. Y2O3:Er3+,Yb3+, are promising candidates for NIR-NIR bioimaging. Ln3+-doped gadolinium-based inorganic nanostructures, such as Gd2O3:Er3+,Yb3+, have a high potential as opto-magnetic markers allowing the combination of time-resolved optical imaging and magnetic resonance imaging (MRI) of high spatial resolution. Recent progress in our research on over-1000 nm NIR fluorescent nanoprobes for in vivo NIR-NIR bioimaging will be discussed in this review.In recent years, significant progress was achieved in the field of nanomedicine and bioimaging, but the development of new biomarkers for reliable detection of diseases at an early stage, molecular imaging, targeting and therapy remains crucial. The disadvantages of commonly used organic dyes include photobleaching, autofluorescence, phototoxicity and scattering when UV (ultraviolet) or visible light is used for excitation. The limited penetration depth of the excitation light and the visible emission into and from the biological tissue is a further drawback with regard to in vivo bioimaging. Lanthanide containing inorganic nanostructures emitting in the near-infrared (NIR) range under NIR excitation may overcome those problems. Due to the outstanding optical and magnetic properties of lanthanide ions (Ln3+), nanoscopic host materials doped with Ln3+, e.g. Y2O3:Er3+,Yb3+, are promising candidates for NIR-NIR bioimaging. Ln3+-doped gadolinium-based inorganic nanostructures, such as Gd2O3:Er3+,Yb3+, have a high potential as opto-magnetic markers allowing the combination of time-resolved optical imaging and magnetic resonance imaging (MRI) of high spatial resolution. Recent progress in our research on over-1000 nm NIR fluorescent nanoprobes for in vivo NIR-NIR bioimaging will be discussed in this review. Electronic supplementary information (ESI) available: Table 1: sample overview. Movie 1: time-resolved in vivo biodistribution of Gd2O3:Er3+,Yb3+ nanorods in a mouse 5 min post-injection. Fig. 1: preliminary long-term cytotoxicity study of Y2O3:Er3+ injected into mice. See DOI: 10.1039/c3nr02286b

Nitrogen fixation studies, lead detection in living plants, and solar wind analysis

NASA Technical Reports Server (NTRS)

Libby, W. F.

1971-01-01

Progress is reported for research on the following: (1) magnetically shielded test facility studies; (2) electrochemistry of B10C2H12, B9CH10(-), and preparation of tumor specific boron containing materials for use in cancer therapy; (3) histochemical method for determining lead in living plant tissue; (4) diamond cementing; (5) analysis of solar wind using the washings of lunar fines; and (6) environmental engineering.

Rare earth fluoride nano-/microstructures: hydrothermal synthesis, luminescent properties and applications.

PubMed

Zhao, Qian; Xu, Zhenhe; Sun, Yaguang

2014-02-01

Rare earth fluoride materials have attracted wide interest and come to the forefront in nanophotonics due to their distinct electrical, optical and magnetic properties as well as their potential applications in diverse fields such as optical telecommunication, lasers, biochemical probes, infrared quantum counters, and medical diagnostics. This review presents a comprehensive overview of the flourishing field of rare earth fluorides materials in the past decade. We summarize the recent research progress on the preparation, morphology, luminescent properties and application of rare earth fluoride-based luminescent materials by hydrothermal systems. Various rare earth fluoride materials are obtained by fine-tuning of experimental conditions, such as capping agents, fluoride source, acidity, temperature and reaction time. The controlled morphology, luminescent properties and application of the rare earth fluorides are briefly discussed with typical examples.

Magnetic measurements of the transuranium elements. Progress report, January 1, 1984-December 31, 1984

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huray, P.G.; Nave, S.E.

1984-01-01

Measurements of the magnetic properties of dhcp californium-249 metal indicated the presence of three regions of differing magnetic character. Additional measurements are also reported. Magnetic moments and valence states of terbium in TbF/sub 3/, BaTbO/sub 3/, and TbO/sub 1/ /sub 8/ are discussed. Progress on high-field operation of the micro-magnetic susceptometer is reported.

Damping in Materials for Spintronic Applications

NASA Astrophysics Data System (ADS)

Mewes, Claudia

The next generation of spintronic devices relies strongly on the development of new materials with high spin polarization, optimized intrinsic damping and tunable magnetic anisotropy. Therefore, technological progress in this area depends heavily on the successful search for new materials as well as on a deeper understanding of the fundamental mechanisms of the spin polarization, the damping and the magnetic anisotropy. This talk will focus on different aspects of materials with a low intrinsic relaxation rate. Our results are based on first principles calculations in combination with a non-orthogonal tight-binding model to predict those material properties for complex materials which can be used for example in new spin based memory devices or logic devices. However, the intrinsic damping parameter predicted from first principle calculations does not take into account adjacent layers that are present in the final device. Spin pumping is a well-known contribution that has to be taken into account for practical applications using multilayer structures. More recently a strong unidirectional contribution to the relaxation in exchange bias systems has been observed experimentally. To describe this phenomenon theoretically we use the formalism of an anisotropic Gilbert damping tensor that takes the place of the (scalar) Gilbert damping parameter in the Landau-Lifshitz-Gilbert equation of motion. While for single crystals this anisotropy is expected to be small, making experimental confirmation difficult, the broken symmetry in exchange bias systems provides an excellent testing ground to study the modified magnetization dynamics under the influence of unidirectional damping. C.K.A. Mewes would like to thank her colleague T. Mewes and her students J.B. Mohammadi, A.E. Farrar. We acknowledge support by the NSF-CAREER Award No. 1452670, and NSF-CAREER Award No. 0952929.

Formation of Maximum Eddy Current Force by Non Ferrous Materials

NASA Astrophysics Data System (ADS)

Kader, M. M. A.; Razali, Z. B.; Yasin, N. S. M.; Daud, M. H.

2018-03-01

This project is concerned with the study of eddy current effects on various materials such as aluminum, copper and magnesium. Two types of magnets used in this study; magnetic ferrite (ZnFe+2O4) and magnetic neodymium (NdFeBN42). Eddy current force will be exerted to these materials due to current flows along the magnet. This force depends on the type of magnet, type of material and the gap between the magnet and the material or between the two magnets. The results show that at constant magnet to material gap, the eddy current force decreases as the magnet to magnet gap increases. Similarly, at constant magnet to magnet gap, the eddy current force decreases as the magnet to material gap increases. The minimum force was achieved when the gap of magnet to material is maximum, similarly to the gap of magnet to magnet. The weakest force was between Copper and Neodymium at a magnet to material gap of 20 mm and magnet to magnet gap of 40 mm; the eddy current force was 0.00048 N. The strongest force (maximum) was between Magnesium and Ferrite and 0.42273 N at a magnet to material gap of 3 mm and magnet to magnet gap of 5 mm.

Capture of nonmagnetic particles and living cells using a microelectromagnetic system

NASA Astrophysics Data System (ADS)

Aki, Atsushi; Ito, Osamu; Morimoto, Hisao; Nagaoka, Yutaka; Nakajima, Yoshikata; Mizuki, Toru; Hanajiri, Tatsuro; Usami, Ron; Maekawa, Toru

2008-11-01

We develop a microelectromagnetic system to trap nonmagnetic materials such as micropolystyrene particles and yeast cells in particular areas. We fabricate gold films, the width of the central narrow part is 22 μm, and flow an electric current through the films. We then apply an external uniform dc magnetic field to weaken the local magnetic field at the narrow part so that a nonuniform magnetic field is produced. We demonstrate that the particles, which are dispersed in magnetic fluid, are successfully trapped at the narrow part of the film. We evaluate the driving force acting on a microparticle in the nonuniform magnetic field and carry out a Stokesian dynamics simulation of the motion of the particles. We show that yeast cells are also trapped at the narrow part of the film. Finally, we fabricate multichannel microelectromagnets so that yeast cells are trapped at multiple points in the microelectromagnetic system. The present system may be applied to cell transfection on a cell microarray and, therefore, eventually contribute to progress in the identification and determination technologies of different drug targets and the functions of genes and proteins.

Glyconanoparticles: types, synthesis and applications in glycoscience, biomedicine and material science.

PubMed

de la Fuente, Jesús M; Penadés, Soledad

2006-04-01

Nanoparticles are the subject of numerous papers and reports and are full of promises for electronic, optical, magnetic and biomedical applications. Although metallic nanoparticles have been functionalized with peptides, proteins and DNA during the last 20 years, carbohydrates have not been used with this purpose until 2001. Since the first synthesis of gold nanoparticles functionalized with carbohydrates (glyconanoparticles) was reported, the number of published articles has considerably increased. This article reviews progress in the development of nanoparticles functionalized with biological relevant oligosaccharides. The glyconanoparticles constitute a good bio-mimetic model of carbohydrate presentation at the cell surface, and maybe, excellent tools for Glycobiology, Biomedicine and Material Science investigations.

Defect induced electronic states and magnetism in ball-milled graphite.

PubMed

Milev, Adriyan; Dissanayake, D M A S; Kannangara, G S K; Kumarasinghe, A R

2013-10-14

The electronic structure and magnetism of nanocrystalline graphite prepared by ball milling of graphite in an inert atmosphere have been investigated using valence band spectroscopy (VB), core level near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and magnetic measurements as a function of the milling time. The NEXAFS spectroscopy of graphite milled for 30 hours shows simultaneous evolution of new states at ~284.0 eV and at ~290.5 eV superimposed upon the characteristic transitions at 285.4 eV and 291.6 eV, respectively. The modulation of the density of states is explained by evolution of discontinuities within the sheets and along the fracture lines in the milled graphite. The magnetic measurements in the temperature interval 2-300-2 K at constant magnetic field strength show a correlation between magnetic properties and evolution of the new electronic states. With the reduction of the crystallite sizes of the graphite fragments, the milled material progressively changes its magnetic properties from diamagnetic to paramagnetic with contributions from both Pauli and Curie paramagnetism due to the evolution of new states at ~284 and ~290.5 eV, respectively. These results indicate that the magnetic behaviour of ball-milled graphite can be manipulated by changing the milling conditions.

Direct measurement of the spin gap in a quasi-one-dimensional clinopyroxene: NaTiSi 2 O 6

DOE PAGES

Silverstein, Harlyn J.; Smith, Alison E.; Mauws, Cole; ...

2014-10-13

True inorganic Spin-Peierls materials are extremely rare, but NaTiSi 2O 6 was at one time considered an ideal candidate due to it having well separated chains of edge-sharing TiO 6 octahedra. At low temperatures, this material undergoes a phase transition from C2/c to Pmore » $$\\bar{1}$$ symmetry, where Ti 3+-Ti 3+ dimers begin to form within the chains. However, it was quickly realized with magnetic susceptibility that simple spin fluctuations do not progress to the point of enabling such a transition. Since then, considerable experimental and theoretical endeavours have been taken to find the true ground state of this system and explain how it manifests. Here, we employ the use of x-ray diffraction, neutron spectroscopy, and magnetic susceptibility to directly and simultaneously measure the symmetry loss, spin singlet-triplet gap, and phonon modes. Lastly, we observed a gap of 53(3) meV, fit to the magnetic susceptibility, and compared to previous theoretical models to unambiguously assign NaTiSi 2O 6 as having an orbital-assisted Peierls ground state.« less

Electric Motor Thermal Management Research: Annual Progress Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bennion, Kevin S.

Past work in the area of active convective cooling provided data on the average convective heat transfer coefficients of circular orifice automatic transmission fluid (ATF) jets impinging on stationary targets intended to represent the wire bundle surface of the motor end-winding. Work during FY16 focused on the impact of alternative jet geometries that could lead to improved cooling over a larger surface of the motor winding. Results show that the planar jet heat transfer coefficients over a small (12.7-mm-diameter) target surface are not too much lower than for the circular orifice jet in which all of the ATF from themore » jet impinges on the target surface. The planar jet has the potential to achieve higher heat transfer over a larger area of the motor end winding. A new test apparatus was constructed to measure the spatial dependence of the heat transfer relative to the jet nozzle over a larger area representative of a motor end-winding. The tested planar flow geometry has the potential to provide more uniform cooling over the full end-winding surface versus the conventional jet configuration. The data will be used by motor designers to develop thermal management strategies to improve motor power density. Work on passive thermal design in collaboration with Oak Ridge National Laboratory to measure the thermal conductivity of wire bundle samples representative of end-winding and slot-winding materials was completed. Multiple measurement techniques were compared to determine which was most suitable for measuring composite wire bundle samples. NREL used a steady-state thermal resistance technique to measure the direction-dependent thermal conductivity. The work supported new interactions with industry to test new materials and reduce passive-stack thermal resistance in motors, leading to motors with increased power density. NREL collaborated with Ames Laboratory in the area of material characterization. The work focused on measuring the transverse rupture strength of new magnet materials developed at Ames. The impact of the improved transverse rupture strength is a mechanically stronger magnet that is easier for manufacturers to implement into motor designs. The thermal conductivity of the new magnet materials was also measured in comparison to two commercially available AlNiCo magnet materials. The impact of the thermal conductivity of the magnet material will need to be analyzed in the context of a motor application.« less

Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit

DOE PAGES

Huang, Bevin; Clark, Genevieve; Navarro-Moratalla, Efrén; ...

2017-06-07

Since the celebrated discovery of graphene, the family of two-dimensional (2D) materials has grown to encompass a broad range of electronic properties. Recent additions include spin-valley coupled semiconductors, Ising superconductors that can be tuned into a quantum metal, possible Mott insulators with tunable charge-density waves, and topological semi-metals with edge transport. Despite this progress, there is still no 2D crystal with intrinsic magnetism, which would be useful for many technologies such as sensing, information, and data storage. Theoretically, magnetic order is prohibited in the 2D isotropic Heisenberg model at finite temperatures by the Mermin-Wagner theorem. However, magnetic anisotropy removes thismore » restriction and enables, for instance, the occurrence of 2D Ising ferromagnetism. Here, we use magneto-optical Kerr effect (MOKE) microscopy to demonstrate that monolayer chromium triiodide (CrI 3) is an Ising ferromagnet with out-of-plane spin orientation. Its Curie temperature of 45 K is only slightly lower than the 61 K of the bulk crystal, consistent with a weak interlayer coupling. Moreover, our studies suggest a layer-dependent magnetic phases, showcasing the hallmark thickness dependent physical properties typical of van der Waals crystals. Remarkably, bilayer CrI3 displays suppressed magnetization with a metamagnetic effect, while in trilayer the interlayer ferromagnetism observed in the bulk crystal is restored. Our work creates opportunities for studying magnetism by harnessing the unique features of atomically-thin materials, such as electrical control for realizing magnetoelectronics, and van der Waals engineering for novel interface phenomena.« less

Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Bevin; Clark, Genevieve; Navarro-Moratalla, Efrén

Since the celebrated discovery of graphene, the family of two-dimensional (2D) materials has grown to encompass a broad range of electronic properties. Recent additions include spin-valley coupled semiconductors, Ising superconductors that can be tuned into a quantum metal, possible Mott insulators with tunable charge-density waves, and topological semi-metals with edge transport. Despite this progress, there is still no 2D crystal with intrinsic magnetism, which would be useful for many technologies such as sensing, information, and data storage. Theoretically, magnetic order is prohibited in the 2D isotropic Heisenberg model at finite temperatures by the Mermin-Wagner theorem. However, magnetic anisotropy removes thismore » restriction and enables, for instance, the occurrence of 2D Ising ferromagnetism. Here, we use magneto-optical Kerr effect (MOKE) microscopy to demonstrate that monolayer chromium triiodide (CrI 3) is an Ising ferromagnet with out-of-plane spin orientation. Its Curie temperature of 45 K is only slightly lower than the 61 K of the bulk crystal, consistent with a weak interlayer coupling. Moreover, our studies suggest a layer-dependent magnetic phases, showcasing the hallmark thickness dependent physical properties typical of van der Waals crystals. Remarkably, bilayer CrI3 displays suppressed magnetization with a metamagnetic effect, while in trilayer the interlayer ferromagnetism observed in the bulk crystal is restored. Our work creates opportunities for studying magnetism by harnessing the unique features of atomically-thin materials, such as electrical control for realizing magnetoelectronics, and van der Waals engineering for novel interface phenomena.« less

Generalized Kerker effects in nanophotonics and meta-optics [Invited

NASA Astrophysics Data System (ADS)

Liu, Wei; Kivshar, Yuri S.

2018-05-01

The original Kerker effect was introduced for a hypothetical magnetic sphere, and initially it did not attract much attention due to a lack of magnetic materials required. Rejuvenated by the recent explosive development of the field of metamaterials and especially its core concept of optically-induced artificial magnetism, the Kerker effect has gained an unprecedented impetus and rapidly pervaded different branches of nanophotonics. At the same time, the concept behind the effect itself has also been significantly expanded and generalized. Here we review the physics and various manifestations of the generalized Kerker effects, including the progress in the emerging field of meta-optics that focuses on interferences of electromagnetic multipoles of different orders and origins. We discuss not only the scattering by individual particles and particle clusters, but also the manipulation of reflection, transmission, diffraction, and absorption for metalattices and metasurfaces, revealing how various optical phenomena observed recently are all ubiquitously related to the Kerker's concept.

Synthesis, characterization and in vivo evaluation of biocompatible ferrogels

NASA Astrophysics Data System (ADS)

Lopez-Lopez, M. T.; Rodriguez, I. A.; Rodriguez-Arco, L.; Carriel, V.; Bonhome-Espinosa, A. B.; Campos, F.; Zubarev, A.; Duran, J. D. G.

2017-06-01

A hydrogel is a 3-D network of polymer chains in which water is the dispersion medium. Hydrogels have found extensive applications in the biomedical field due to their resemblance to living tissues. Furthermore, hydrogels can be endowed with exceptional properties by addition of synthetic materials. For example, magnetic field-sensitive gels, called ferrogels, are obtained by embedding magnetic particles in the polymer network. Novel living tissues with unique magnetic field-sensitive properties were recently prepared by 3-D cell culture in biocompatible ferrogels. This paper critically reviews the most recent progress and perspectives in their synthesis, characterization and biocompatibility evaluation. Optimization of ferrogels for this novel application requires low-density, strongly magnetic, multi-domain particles. Interestingly, the rheological properties of the resulting ferrogels in the absence of field were largely enhanced with respect to nonmagnetic hydrogels, which can only be explained by the additional cross-linking imparted by the embedded magnetic particles. Remarkably, rheological measurements under an applied magnetic field demonstrated that ferrogels presented reversibly tunable mechanical properties, which constitutes a unique advantage with respect to nonmagnetic hydrogels. In vivo evaluation of ferrogels showed good biocompatibility, with only some local inflammatory response, and no particle migration or damage to distant organs.

Fascinating Magnetic Energy Storage Nanomaterials: A Brief Review.

PubMed

Sreenivasulu, Kummari V; Srikanth, Vadali V S S

2017-07-10

In this brief review, the importance of nanotechnology in developing novel magnetic energy storage materials is discussed. The discussion covers recent patents on permanent magnetic materials and especially covers processing of permanent magnets (rare-earth and rare-earth free magnets), importance of rare-earth permanent magnets and necessity of rare-earth free permanent magnets. Magnetic energy storage materials are those magnetic materials which exhibit very high energy product (BH)max (where B is the magnetic induction in Gauss (G) whereas H is the applied magnetic field in Oersted (Oe)). (BH)max is the direct measure of the ability of a magnetic material to store energy. In this context, processing of magnetic energy storage composite materials constituted by soft and hard magnetic materials played a predominant role in achieving high (BH)max values due to the exchange coupling phenomenon between the soft and hard magnetic phases within the composite. Magnetic energy storage composites are normally composed of rare-earth magnetic materials as well as rare-earth free magnetic materials. Nanotechnology's influence on the enhancement of energy product due to the exchange coupling phenomenon is of great prominence and therefore discussed in this review. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Tunable electronic and magnetic properties of two‐dimensional materials and their one‐dimensional derivatives

PubMed Central

Zhang, Zhuhua; Liu, Xiaofei; Yu, Jin; Hang, Yang; Li, Yao; Guo, Yufeng; Xu, Ying; Sun, Xu; Zhou, Jianxin

2016-01-01

Low‐dimensional materials exhibit many exceptional properties and functionalities which can be efficiently tuned by externally applied force or fields. Here we review the current status of research on tuning the electronic and magnetic properties of low‐dimensional carbon, boron nitride, metal‐dichalcogenides, phosphorene nanomaterials by applied engineering strain, external electric field and interaction with substrates, etc, with particular focus on the progress of computational methods and studies. We highlight the similarities and differences of the property modulation among one‐ and two‐dimensional nanomaterials. Recent breakthroughs in experimental demonstration of the tunable functionalities in typical nanostructures are also presented. Finally, prospective and challenges for applying the tunable properties into functional devices are discussed. WIREs Comput Mol Sci 2016, 6:324–350. doi: 10.1002/wcms.1251 For further resources related to this article, please visit the WIREs website. Conflict of interest: The authors have declared no conflicts of interest for this article. PMID:27818710

Piezoelectric and Magnetoelectric Thick Films for Fabricating Power Sources in Wireless Sensor Nodes

PubMed Central

Priya, Shashank; Ryu, Jungho; Park, Chee-Sung; Oliver, Josiah; Choi, Jong-Jin; Park, Dong-Soo

2009-01-01

In this manuscript, we review the progress made in the synthesis of thick film-based piezoelectric and magnetoelectric structures for harvesting energy from mechanical vibrations and magnetic field. Piezoelectric compositions in the system Pb(Zr,Ti)O3–Pb(Zn1/3Nb2/3)O3 (PZNT) have shown promise for providing enhanced efficiency due to higher energy density and thus form the base of transducers designed for capturing the mechanical energy. Laminate structures of PZNT with magnetostrictive ferrite materials provide large magnitudes of magnetoelectric coupling and are being targeted to capture the stray magnetic field energy. We analyze the models used to predict the performance of the energy harvesters and present a full system description. PMID:22454590

Machine Learning Approach for Classifying Multiple Sclerosis Courses by Combining Clinical Data with Lesion Loads and Magnetic Resonance Metabolic Features.

PubMed

Ion-Mărgineanu, Adrian; Kocevar, Gabriel; Stamile, Claudio; Sima, Diana M; Durand-Dubief, Françoise; Van Huffel, Sabine; Sappey-Marinier, Dominique

2017-01-01

Purpose: The purpose of this study is classifying multiple sclerosis (MS) patients in the four clinical forms as defined by the McDonald criteria using machine learning algorithms trained on clinical data combined with lesion loads and magnetic resonance metabolic features. Materials and Methods: Eighty-seven MS patients [12 Clinically Isolated Syndrome (CIS), 30 Relapse Remitting (RR), 17 Primary Progressive (PP), and 28 Secondary Progressive (SP)] and 18 healthy controls were included in this study. Longitudinal data available for each MS patient included clinical (e.g., age, disease duration, Expanded Disability Status Scale), conventional magnetic resonance imaging and spectroscopic imaging. We extract N -acetyl-aspartate (NAA), Choline (Cho), and Creatine (Cre) concentrations, and we compute three features for each spectroscopic grid by averaging metabolite ratios (NAA/Cho, NAA/Cre, Cho/Cre) over good quality voxels. We built linear mixed-effects models to test for statistically significant differences between MS forms. We test nine binary classification tasks on clinical data, lesion loads, and metabolic features, using a leave-one-patient-out cross-validation method based on 100 random patient-based bootstrap selections. We compute F1-scores and BAR values after tuning Linear Discriminant Analysis (LDA), Support Vector Machines with gaussian kernel (SVM-rbf), and Random Forests. Results: Statistically significant differences were found between the disease starting points of each MS form using four different response variables: Lesion Load, NAA/Cre, NAA/Cho, and Cho/Cre ratios. Training SVM-rbf on clinical and lesion loads yields F1-scores of 71-72% for CIS vs. RR and CIS vs. RR+SP, respectively. For RR vs. PP we obtained good classification results (maximum F1-score of 85%) after training LDA on clinical and metabolic features, while for RR vs. SP we obtained slightly higher classification results (maximum F1-score of 87%) after training LDA and SVM-rbf on clinical, lesion loads and metabolic features. Conclusions: Our results suggest that metabolic features are better at differentiating between relapsing-remitting and primary progressive forms, while lesion loads are better at differentiating between relapsing-remitting and secondary progressive forms. Therefore, combining clinical data with magnetic resonance lesion loads and metabolic features can improve the discrimination between relapsing-remitting and progressive forms.

EDITORIAL: Selected papers from the 19th International Colloquium on Magnetic Films and Surfaces

NASA Astrophysics Data System (ADS)

Miyazaki, T.; Inoue, J.

2007-03-01

The 19th International Colloquium on Magnetic Films and Surfaces (ICMFS 2006) was held on 14-18 August 2006 at the Sendai International Center in Sendai, Japan. The purpose of the Colloquium was to bring together scientists working on magnetic thin films and surfaces and to provide an opportunity for presentation and discussion of recent experimental and theoretical advances in the field. 285 scientists from 17 countries (Japan: 167, overseas: 118) participated in the Colloquium, as well as 6 family members. There were 56 oral and 178 poster presentations. The oral presentations consisted of 3 plenary talks, 23 invited talks and 30 contributed talks. The number of presentations by scientific category are as follows: Spin dependent transport: 43 Magnetic storage/memory: 9 Magnetization reversal and fast dynamics: 15 Spin injection and spin transfer torque: 26 Magnetic thin films and multilayers: 71 High spin polarization materials: 17 Hard and soft magnetic materials: 3 Magneto-optics: 5 Characterization techniques for thin films and surfaces: 7 Exchange coupling: 13 Micro- and nanopatterned magnetic structures: 18 Micromagnetic modelling: 2 One of the characteristics of the present Colloquium is an increase in the number of presentations in the field of spin-electronics, as seen above. This Cluster Issue of Journal of Physics D: Applied Physics includes several important papers in this rapidly developing field. We believe that, in the future, the field of magnetic materials will maintain its popularity and, on top of that, other fields such as spintronics materials, materials related to life sciences and medicine and also materials related to the environment will be investigated further. The ICMFS Conference started in London in 1964, and is now one of the world-wide conferences on magnetism. The Colloquium has been held in Japan four times now: the previous ones being the 5th ICMFS in the Mount Fuji area, the 10th at Yokohama and the 17th at Kyoto, which was organized by Professors Shinjo and Maekawa. The city of Sendai, where the 19th ICMFS was held, is the historical place for magnetism research in Japan. Kotaro Honda, who was a professor of Tohoku University in Sendai, laid the foundation for this research in Japan, and he was followed by Siji Kaya, Haraku Masumoto and Minoru Takahashi, also professors of Tohoku University. They continued the spirit founded by Honda and contributed greatly to the progress of research in magnetism. Therefore, it was a great pleasure for the organizers to have the ICMFS Conference come to Sendai. The 19th ICMFS Colloquium was co-hosted by the Japanese Society for the Promotion of Science and the Foundation Advanced Technology Institute and supported by the Japanese Society of Applied Physics, the Magnetics Society of Japan, the Physical Society of Japan and the Japan Institute of Metals. This colloquium was also jointly held with the Conference on the Physics and Application of Spin-related Phenomena in Semiconductors (PASPS). All the members of the Organizing Committee would like to thank the members of the International Advisory Committee for scientific and administrative advice, and the Sendai Tourism and Convention Bureau, the Iwatani Naoji Foundation, the Asahi Glass Foundation and the Intelligent Cosmos Academic Foundation for their financial support. Without doubt, the Colloquium was a great success overall. The smooth and excellent running of the Colloquium would not have been possible without the assistance of the Program Committee and local members of the Colloquium.

Mechanical and electrical properties of low temperature phase MnBi

NASA Astrophysics Data System (ADS)

Jiang, Xiujuan; Roosendaal, Timothy; Lu, Xiaochuan; Palasyuk, Olena; Dennis, Kevin W.; Dahl, Michael; Choi, Jung-Pyung; Polikarpov, Evgueni; Marinescu, Melania; Cui, Jun

2016-01-01

Low temperature phase (LTP) manganese bismuth (MnBi) is a promising rare-earth-free permanent magnet material due to its high intrinsic coercivity and large positive temperature coefficient. While scientists are making progress on fabricating bulk MnBi magnets, engineers have begun considering MnBi magnets for motor applications. Physical properties other than magnetic ones could significantly affect motor design. Here, we report results of our investigation on the mechanical and electrical properties of bulk LTP MnBi and their temperature dependence. A MnBi ingot was prepared using an arc melting technique and subsequently underwent grinding, sieving, heat treatment, and cryomilling. The resultant powders with a particle size of ˜5 μm were magnetically aligned, cold pressed, and sintered at a predefined temperature. Micro-hardness testing was performed on a part of original ingot and we found that the hardness of MnBi was 109 ± 15 HV. The sintered magnets were subjected to compressive testing at different temperatures and it was observed that a sintered MnBi magnet fractured when the compressive stress exceeded 193 MPa at room temperature. Impedance spectra were obtained using electrochemical impedance spectroscopy at various temperatures and we found that the electrical resistance of MnBi at room temperature was about 6.85 μΩ m.

Engineering magnetism at functional oxides interfaces: manganites and beyond

NASA Astrophysics Data System (ADS)

Yi, Di; Lu, Nianpeng; Chen, Xuegang; Shen, Shengchun; Yu, Pu

2017-11-01

The family of transition metal oxides (TMOs) is a large class of magnetic materials that has been intensively studied due to the rich physics involved as well as the promising potential applications in next generation electronic devices. In TMOs, the spin, charge, orbital and lattice are strongly coupled, and significant advances have been achieved to engineer the magnetism by different routes that manipulate these degrees of freedom. The family of manganites is a model system of strongly correlated magnetic TMOs. In this review, using manganites thin films and the heterostructures in conjunction with other TMOs as model systems, we review the recent progress of engineering magnetism in TMOs. We first discuss the role of the lattice that includes the epitaxial strain and the interface structural coupling. Then we look into the role of charge, focusing on the interface charge modulation. Having demonstrated the static effects, we continue to review the research on dynamical control of magnetism by electric field. Next, we review recent advances in heterostructures comprised of high T c cuprate superconductors and manganites. Following that, we discuss the emergent magnetic phenomena at interfaces between 3d TMOs and 5d TMOs with strong spin-orbit coupling. Finally, we provide our outlook for prospective future directions.

A 37,000-year environmental magnetic record of aeolian dust deposition from Burial Lake, Arctic Alaska

NASA Astrophysics Data System (ADS)

Dorfman, J. M.; Stoner, J. S.; Finkenbinder, M. S.; Abbott, M. B.; Xuan, C.; St-Onge, G.

2015-11-01

Environmental magnetism and radiocarbon dating of Burial Lake sediments constrain the timing and magnitude of regional aeolian deposition for the Noatak region of western Arctic Alaska for the last ∼37,000 years. Burial Lake (68.43°N, 159.17°W, 21.5 m water depth) is optimally located to monitor regional dust deposition because it is perched above local drainage and isolated from glacial processes. Cores collected in the summer of 2010 were studied through the application of magnetizations and progressive alternating field (AF) demagnetization of u-channel samples, with additional data provided by computed tomography (CT) derived density, hysteresis measurements, isothermal remanent magnetization (IRM) acquisition experiments, organic carbon content, biogenic silica, physical grain size, radiocarbon dating of wood, seeds, and plant macrofossils, point source magnetic susceptibility, and X-ray fluorescence (XRF). With similar magnetic properties to regional Alaskan loess deposits, low coercivity, highly magnetic material deposited during the late-Pleistocene contrasts with a high coercivity, weakly magnetic component found throughout the record, consistent with locally-derived detritus. The relative proportion of low coercivity to high coercivity magnetic material, defined by the S-Ratios, is used to reconstruct the regional input of dust to the basin over time. A four-fold decrease in the low coercivity component through the deglacial transition is interpreted to reflect diminished dust input to the region. Comparisons with potential sources of dust show that the timing of deposition in Burial Lake is largely consistent with general aridity, lack of vegetative cover, and increased windiness, rather than glacial advances or retreats. The influence from subaerial exposure of continental shelves cannot be ruled out as a significant far-field source of dust to interior Alaska during the Last Glacial Maximum (LGM), but is unlikely to have been the sole source, or to have contributed to increased dust in both the early and late Holocene.

Superconducting selenides intercalated with organic molecules: synthesis, crystal structure, electric and magnetic properties, superconducting properties, and phase separation in iron based-chalcogenides and hybrid organic-inorganic superconductors

NASA Astrophysics Data System (ADS)

Krzton-Maziopa, Anna; Pesko, Edyta; Puzniak, Roman

2018-06-01

Layered iron-based superconducting chalcogenides intercalated with molecular species are the subject of intensive studies, especially in the field of solid state chemistry and condensed matter physics, because of their intriguing chemistry and tunable electric and magnetic properties. Considerable progress in the research, revealing superconducting inorganic–organic hybrid materials with transition temperatures to superconducting state, T c, up to 46 K, has been brought in recent years. These novel materials are synthesized by low-temperature intercalation of molecular species, such as solvates of alkali metals and nitrogen-containing donor compounds, into layered FeSe-type structure. Both the chemical nature as well as orientation of organic molecules between the layers of inorganic host, play an important role in structural modifications and may be used for fine tuning of superconducting properties. Furthermore, a variety of donor species compatible with alkali metals, as well as the possibility of doping also in the host structure (either on Fe or Se sites), makes this system quite flexible and gives a vast array of new materials with tunable electric and magnetic properties. In this review, the main aspects of intercalation chemistry are discussed with a particular attention paid to the influence of the unique nature of intercalating species on the crystal structure and physical properties of the hybrid inorganic–organic materials. To get a full picture of these materials, a comprehensive description of the most effective chemical and electrochemical methods, utilized for synthesis of intercalated species, with critical evaluation of their strong and weak points, related to feasibility of synthesis, phase purity, crystal size and morphology of final products, is included as well.

Synthesis of nanostructured iron oxides dispersed in carbon materials and in situ XRD study of the changes caused by thermal treatment

NASA Astrophysics Data System (ADS)

Gonçalves, Gustavo R.; Schettino, Miguel A.; Morigaki, Milton K.; Nunes, Evaristo; Cunha, Alfredo G.; Emmerich, Francisco G.; Passamani, Edson C.; Baggio-Saitovitch, Elisa; Freitas, Jair C. C.

2015-07-01

Carbon-based magnetic nanocomposites are of large interest for applications in catalysis, magnetic separation, water cleaning, and magnetic resonance imaging, among others. This work describes the synthesis of nanocomposites consisting of iron oxides dispersed into a char (obtained from the carbonization at 700 °C of a lignocellulosic precursor) and the study of the thermal transformations occurring in these materials as a consequence of heat treatments. The materials were prepared by impregnation of the char with iron nitrate in the presence of ammonium hydroxide in aqueous suspension. X-ray diffraction experiments performed using synchrotron radiation and Mössbauer spectroscopy showed that the as-prepared material was composed of amorphous Fe3+ oxides. Scanning electron microscopy images combined with energy-dispersive X-ray spectrometry indicated a homogeneous dispersion of iron oxides and of silica particles (naturally present in the lignocellulosic precursor) throughout the char. X-ray diffractograms recorded in situ during the heat treatment of the as-prepared material showed the presence of small hematite crystallites (average size 22 nm) starting from ca. 300 °C. Further heating caused a progressive growth of the hematite crystallites up to ca. 500 °C, when the conversion to magnetite (Fe3O4) started to take place. At higher temperatures, wüstite (Fe1-xO) was detected as an intermediate phase and austenitic iron (γ-Fe) became the dominant phase at temperatures from 900 °C. A steep weight loss was observed in the TG curve accompanying this last reduction stage; upon cooling, γ-Fe was converted into α-Fe (ferrite), which was the dominant phase at room temperature in this heat-treated sample.

Sequential contrast-enhanced MR imaging of the penis.

PubMed

Kaneko, K; De Mouy, E H; Lee, B E

1994-04-01

To determine the enhancement patterns of the penis at magnetic resonance (MR) imaging. Sequential contrast material-enhanced MR images of the penis in a flaccid state were obtained in 16 volunteers (12 with normal penile function and four with erectile dysfunction). Subjects with normal erectile function showed gradual and centrifugal enhancement of the corpora cavernosa, while those with erectile dysfunction showed poor enhancement with abnormal progression. Sequential contrast-enhanced MR imaging provides additional morphologic information for the evaluation of erectile dysfunction.

Tetrazolo(1,5-A)pyridines and Furazano(4,5-B)pyridine-1-oxides as Energetic Materials

DTIC Science & Technology

1989-04-01

alpyridine was isolated, contaminated with about 10% of 16. The azido compound was charac- terized by IR and NMR spectroscopy, and the structure (15...Applications of Nuclear Magnetic Resonance Spectroscopy to Organic Chemistry," Record of Chemical Progress, 23 ( 1962 ), p. 223. 16. A. J. Boulton and A. R...Katritzky. "A New Heterocyclic Rearrangement," Proc. Chem. Soc. ( 1962 ), p. 257. 1 7. A. P. Chafin and D. W. Moore. Unpublished results; F. A. L. Anet

Analysis of the Material Removal Rate in Magnetic Abrasive Finishing of Thin Film Coated Pyrex Glass

NASA Astrophysics Data System (ADS)

Lee, Hee Hwan; Lee, Seoung Hwan

The material removal rate (MRR) during precision finishing/polishing is a key factor, which dictates the process performance. Moreover, the MRR or wear rate is closely related to the material/part reliability. For nanoscale patterning and/or planarization on nano-order thickness coatings, the prediction and in-process monitoring of the MRR is necessary, because the process is not characterizable due to size effects and material property/process condition variations as a result of the coating/substrate interactions. The purpose of this research was to develop a practical methodology for the prediction and in-process monitoring of MRR during nanoscale finishing of coated surfaces. Using a specially designed magnetic abrasive finishing (MAF) and acoustic emission (AE) monitoring setup, experiments were carried out on indium-zinc-oxide (IZO) coated Pyrex glasses. After a given polishing time interval, AFM indentation was conducted for each workpiece sample to measure the adhesion force variations of the coating layers (IZO), which are directly related to the MRR changes. The force variation and AE monitoring data were compared to the MRR calculated form the surface measurement (Nanoview) results. The experimental results demonstrate strong correlations between AFM indentation and MRR measurement data. In addition, the monitored AE signals show sensitivity of the material structure variations of the coating layer, as the polishing progresses.

EDITORIAL: Invited papers from ISAMMA 2010 (Sendai, Japan, 12-16 July 2010) Invited papers from ISAMMA 2010 (Sendai, Japan, 12-16 July 2010)

NASA Astrophysics Data System (ADS)

Takahashi, M.; Saito, H.

2011-02-01

This cluster issue of Journal of Physics D: Applied Physics contains a collection of papers based on invited talks given at the 2nd International Symposium on Advanced Magnetic Materials and Applications 2010 (ISAMMA 2010) held from 12-16 July 2010 in Sendai, Japan. ISAMMA is the first consolidated symposium of three independent symposia held in the Asian region. ISPMM (International Symposium on Physics of Magnetic Materials) of Japan started in 1987 in Sendai, and was held six times: Beijing (1992), Seoul (1995), Sendai (1998), Taipei (2001) and Singapore (2005). ISAMT (International Symposium of Advanced Magnetic Technology) of Taiwan and SOMMA (International Symposium on Magnetic Materials and Applications) of Korea both began in 1999 and were each held five times up to 2005. ISAMMA was established as a new international symposium which will be held every three years in Asia. The concept of this unified international symposium was mainly led by Professor M Takahashi, Conference Chair of ISAMMA 2010. The first memorial symposium, ISAMMA 2007, was held in Jeju Island, Korea, during the period from 28 May to 1 June 2007. The main purpose and scope of ISAMMA is to provide an opportunity for scientists and engineers from all over the world to meet in Asia to discuss recent advances in the study of magnetic materials and their physics, spin-related phenomena and materials. The categories of ISAMMA 2010 were: fundamental properties of magnetic materials; hard/soft magnetic materials and applications; spintronics materials and devices; structured materials; multi functional magnetic materials; spin dynamics and micromagnetics; magnetic storage; materials for applications (sensors, high-frequency, power, and bio/medical devices); magnetic imaging and characterization. The scientific programme began on Tuesday 13 July 2010 with the opening remark by the Symposium Chairman. The conference was attended by 511 participants from 23 countries, with about 40 per cent from overseas. The programme involved 4 plenary talks, 37 invited talks, 85 contributed talks and 352 posters. All submitted papers were reviewed in order to meet the standards of Journal of Physics D: Applied Physics and Journal of Physics: Conference Series. We are grateful to all participants for their valuable contributions and active discussions. We gratefully acknowledge the financial support of 17 Japanese companies and 7 Japanese foundations. Invited papers from ISAMMA 2010 Contents Current status and recent topics of rare-earth permanent magnets S Sugimoto Alloying effect on the magnetic properties of RFeB-type bulk magnets H W Chang, C C Hsieh, J Y Gan, Y T Cheng, M F Shih and W C Chang Coercivity distributions in Nd-Fe-B sintered magnets produced by the grain boundary diffusion process H Nakamura, K Hirota, T Ohashi and T Minowa Recent progress in high Bs Fe-based nanocrystalline soft magnetic alloys M Ohta and Y Yoshizawa Electric-field effects on magnetic anisotropy in Pd/Fe/Pd(0 0 1) surface Shinya Haraguchi, Masahito Tsujikawa, Junpei Gotou and Tatsuki Oda Gate modulation of spin precession in a semiconductor channel Hyun Cheol Koo, Jae Hyun Kwon, Jonghwa Eom, Joonyeon Chang, Suk Hee Han and Mark Johnson Ferromagnetic resonance of epitaxial Fe nanodots grown on MgO measured using coplanar waveguides M Mizuguchi and K Takanashi Switching phase diagrams of current-induced magnetization switching in asymmetric MgO-based magnetic tunnel junctions Seung-Young Park, Jae-Ho Han, Se-Chung Oh, Jang-Eun Lee, Kyung-Tae Nam, Hyun-Woo Lee, Younghun Jo and Kyung-Jin Lee Temperature dependence of spin-dependent transport properties of Co2MnSi-based current-perpendicular-to-plane magnetoresistive devices Y Sakuraba, K Izumi, S Bosu, K Saito and K Takanashi Adsorbate-induced spin-polarization enhancement of Fe3O4(0 0 1) A Pratt, M Kurahashi, X Sun and Y Yamauchi Antiferromagnetic coupling between spinel ferrite and α-Fe layers in Fe3-δO4/MgO/Fe(0 0 1) epitaxial films Hideto Yanagihara, Yuta Toyoda and Eiji Kita Monte Carlo simulations of the magnetocaloric effect in magnetic Ni-Mn-X (X = Ga, In) Heusler alloys V D Buchelnikov, V V Sokolovskiy, S V Taskaev, V V Khovaylo, A A Aliev, L N Khanov, A B Batdalov, P Entel, H Miki and T Takagi Changes in electronic states and magnetic free energy in La1-zCez(FexSi1-x)13 magnetic refrigerants A Fujita, S Fujieda and K Fukamichi Garnet composite films with Au particles fabricated by repetitive formation for enhancement of Faraday effect H Uchida, Y Mizutani, Y Nakai, A A Fedyanin and M Inoue Control of magnetic domain wall displacement using spin current in small in-plane magnetic field in Permalloy nanowires Yoshihiko Togawa, Takashi Kimura, Ken Harada, Akira Tonomura and Yoshichika Otani Magnetic-field tunable transmittance in a ferrofluid-filled silicon nitride photonic crystal slab H M Lee, L Horng and J C Wu Evaluation of a miniature magnetostrictive actuator using Galfenol under tensile stress Toshiyuki Ueno, Hidemitsu Miura and Sotoshi Yamada Sub-nm resolution depth profiling of the magnetic structure of thin films by the depth-resolved x-ray magnetic circular dichroism technique K Amemiya and M Sakamaki

High resistivity iron-based, thermally stable magnetic material for on-chip integrated inductors

DOEpatents

Deligianni, Hariklia; Gallagher, William J.; Mason, Maurice; O'Sullivan, Eugene J.; Romankiw, Lubomyr T.; Wang, Naigang

2017-03-07

An on-chip magnetic structure includes a palladium activated seed layer and a substantially amorphous magnetic material disposed onto the palladium activated seed layer. The substantially amorphous magnetic material includes nickel in a range from about 50 to about 80 atomic % (at. %) based on the total number of atoms of the magnetic material, iron in a range from about 10 to about 50 at. % based on the total number of atoms of the magnetic material, and phosphorous in a range from about 0.1 to about 30 at. % based on the total number of atoms of the magnetic material. The magnetic material can include boron in a range from about 0.1 to about 5 at. % based on the total number of atoms of the magnetic material.

High magnetic field ohmically decoupled non-contact technology

DOEpatents

Wilgen, John [Oak Ridge, TN; Kisner, Roger [Knoxville, TN; Ludtka, Gerard [Oak Ridge, TN; Ludtka, Gail [Oak Ridge, TN; Jaramillo, Roger [Knoxville, TN

2009-05-19

Methods and apparatus are described for high magnetic field ohmically decoupled non-contact treatment of conductive materials in a high magnetic field. A method includes applying a high magnetic field to at least a portion of a conductive material; and applying an inductive magnetic field to at least a fraction of the conductive material to induce a surface current within the fraction of the conductive material, the surface current generating a substantially bi-directional force that defines a vibration. The high magnetic field and the inductive magnetic field are substantially confocal, the fraction of the conductive material is located within the portion of the conductive material and ohmic heating from the surface current is ohmically decoupled from the vibration. An apparatus includes a high magnetic field coil defining an applied high magnetic field; an inductive magnetic field coil coupled to the high magnetic field coil, the inductive magnetic field coil defining an applied inductive magnetic field; and a processing zone located within both the applied high magnetic field and the applied inductive magnetic field. The high magnetic field and the inductive magnetic field are substantially confocal, and ohmic heating of a conductive material located in the processing zone is ohmically decoupled from a vibration of the conductive material.

Ultrafast all-optical control of the magnetization in magnetic dielectrics

NASA Astrophysics Data System (ADS)

Kirilyuk, Andrei; Kimel, Alexey; Hansteen, Fredrik; Rasing, Theo; Pisarev, Roman V.

2006-08-01

The purpose of this review is to summarize the recent progress on laser-induced magnetization dynamics in magnetic dielectrics. Due to the slow phonon-magnon interaction in these materials, direct thermal effects of the laser excitation can only be seen on the time scale of almost a nanosecond and thus are clearly distinguished from the ultrafast nonthermal effects. However, laser pulses are shown to indirectly modify the magnetic anisotropy in rare-earth orthoferrites via the crystal field, and to bring about spin reorientation within a few picoseconds. More interesting, however, are the direct nonthermal effects of light on spin systems. We demonstrate coherent optical control of the magnetization in ferrimagnetic garnet films on a femtosecond time scale through a combination of two different ultrafast and nonthermal photomagnetic effects and by employing multiple pump pulses. Linearly polarized laser pulses are shown to create a long-lived modification of the magnetocrystalline anisotropy via optically induced electron transfer between nonequivalent ion sites. In addition, circularly polarized pulses are shown to act as strong transient magnetic field pulses originating from the nonabsorptive inverse Faraday effect. An all-optical scheme of excitation and detection of different antiferromagnetic resonance modes with frequencies of up to 500GHz will be discussed as well. The reported effects open new and exciting possibilities for ultrafast manipulation of spins by light and provide new insight into the physics of magnetism on ultrafast time scales.

Structural changes concurrent with ferromagnetic transition

NASA Astrophysics Data System (ADS)

Yang, Sen; Bao, Hui-Xin; Zhou, Chao; Wang, Yu; Ren, Xiao-Bing; Song, Xiao-Ping; Yoshitaka, Matsushita; Yoshio, Katsuya; Masahiko, Tanaka; Keisuke, Kobayashi

2013-04-01

Ferromagnetic transition has generally been considered to involve only an ordering of magnetic moment with no change in the host crystal structure or symmetry, as evidenced by a wealth of crystal structure data from conventional X-ray diffractometry (XRD). However, the existence of magnetostriction in all known ferromagnetic systems indicates that the magnetic moment is coupled to the crystal lattice; hence there is a possibility that magnetic ordering may cause a change in crystal structure. With the development of high-resolution synchrotron XRD, more and more magnetic transitions have been found to be accompanied by simultaneous structural changes. In this article, we review our recent progress in understanding the structural change at a ferromagnetic transition, including synchrotron XRD evidence of structural changes at the ferromagnetic transition, a phenomenological theory of crystal structure changes accompanying ferromagnetic transitions, new insight into magnetic morphotropic phase boundaries (MPB) and so on. Two intriguing implications of non-centric symmetry in the ferromagnetic phase and the first-order nature of ferromagnetic transition are also discussed here. In short, this review is intended to give a self-consistent and logical account of structural change occurring simultaneously with a ferromagnetic transition, which may provide new insight for developing highly magneto-responsive materials.

Topology optimization for design of segmented permanent magnet arrays with ferromagnetic materials

NASA Astrophysics Data System (ADS)

Lee, Jaewook; Yoon, Minho; Nomura, Tsuyoshi; Dede, Ercan M.

2018-03-01

This paper presents multi-material topology optimization for the co-design of permanent magnet segments and iron material. Specifically, a co-design methodology is proposed to find an optimal border of permanent magnet segments, a pattern of magnetization directions, and an iron shape. A material interpolation scheme is proposed for material property representation among air, permanent magnet, and iron materials. In this scheme, the permanent magnet strength and permeability are controlled by density design variables, and permanent magnet magnetization directions are controlled by angle design variables. In addition, a scheme to penalize intermediate magnetization direction is proposed to achieve segmented permanent magnet arrays with discrete magnetization directions. In this scheme, permanent magnet strength is controlled depending on magnetization direction, and consequently the final permanent magnet design converges into permanent magnet segments having target discrete directions. To validate the effectiveness of the proposed approach, three design examples are provided. The examples include the design of a dipole Halbach cylinder, magnetic system with arbitrarily-shaped cavity, and multi-objective problem resembling a magnetic refrigeration device.

Magnetic spectroscopy of nanoparticle Brownian motion measurement of microenvironment matrix rigidity.

PubMed

Weaver, John B; Rauwerdink, Kristen M; Rauwerdink, Adam M; Perreard, Irina M

2013-12-01

The rigidity of the extracellular matrix and of the integrin links to the cytoskeleton regulates signaling cascades, controlling critical aspects of cancer progression including metastasis and angiogenesis. We demonstrate that the matrix stiffness can be monitored using magnetic spectroscopy of nanoparticle Brownian motion (MSB). We measured the MSB signal from nanoparticles bound to large dextran polymers. The number of glutaraldehyde induced cross-links was used as a surrogate for material stiffness. There was a highly statistically significant change in the MSB signal with the number of cross-links especially prominent at higher frequencies. The p-values were all highly significant. We conclude that the MSB signal can be used to identify and monitor changes in the stiffness of the local matrix to which the nanoparticles are bound.

Mn-based ferromagnetic semiconductors

NASA Astrophysics Data System (ADS)

Dietl, Tomasz; Sawicki, Maciej

2003-07-01

The present status of research and prospects for device applications of ferromagnetic (diluted magnetic) semiconductors (DMS) is presented. We review the nature of the electronic states and the mechanisms of the carrier-mediated exchange interactions (mean-field Zener model) in p-type Mn-based III-V and II-VI compounds, highlighting a good correspondence of experimental findings and theoretical predictions. An account of the latest progress on the road of increasing the Currie point to above the room temperature is given for both families of compounds. We comment on a possibility of obtaining ferromagnetism in n-type materials, taking (Zn,Mn)O:Al as the example. Concerning technologically important issue of easy axis and domain engineering, we present theoretical predictions and experimental results on the temperature and carrier concentration driven change of magnetic anisotropy in (Ga,Mn)As.

Magneto-thermally responsive hydrogels for bladder cancer treatment: Therapeutic efficacy and in vivo biodistribution.

PubMed

Jaiswal, Manish K; Pradhan, Lina; Vasavada, Shaleen; De, Mrinmoy; Sarma, H D; Prakash, Anand; Bahadur, D; Dravid, Vinayak P

2015-12-01

Bladder cancer is one of the deadliest forms of cancer in modern medicine which despite recent progress has remained incurable and challenging for researchers. There is unmet need to address this endemic as the number of patients are growing by about 10,000 every year world-wide. Here, we report a minimally invasive magnetic chemotherapy method to address this problem where polyethylene glycol (PEG) functionalized Fe3O4 magnetic nanostructures (MNS) are homogeneously embedded in thermally responsive poly(N-isopropylacrylamide, NIPAAm) hydrogels (HG). The system (HG-MNS) loaded with anti-cancer drug doxorubicin (DOX) incubated with cancer cell lines subjected to external radiofrequency (RF) field can remotely stimulate the release of drug smartly at the site. The in vitro efficacy investigated on bladder cancer (T-24) cell lines showed the potential of the system in dealing with the disease successfully. Further, the materials preferential accumulation via systemic delivery was studied using swiss mice model. Vital tissue organs like liver, lung and heart were analysed by magnetic resonance imaging (MRI). A detail accounts of the materials optimization, cytotoxicity and anti-proliferation activity tests with apoptosis analysis by flow cytometry after RF exposure (250 kHz) to the cells and in vivo biodistribution data are discussed in the paper. Copyright © 2015 Elsevier B.V. All rights reserved.

Magnetic Shielding Design for Coupler of Wireless Electric Vehicle Charging Using Finite Element Analysis

NASA Astrophysics Data System (ADS)

Zhao, W. N.; Yang, X. J.; Yao, C.; Ma, D. G.; Tang, H. J.

2017-10-01

Inductive power transfer (IPT) is a practical and preferable method for wireless electric vehicle (EV) charging which proved to be safe, convenient and reliable. Due to the air gap between the magnetic coupler, the magnetic field coupling decreases and the magnetic leakage increases significantly compared to traditional transformer, and this may lead to the magnetic flux density around the coupler more than the safety limit for human. So magnetic shielding should be adding to the winding made from litz wire to enhance the magnetic field coupling effect in the working area and reduce magnetic field strength in non-working area. Magnetic shielding can be achieved by adding high-permeability material or high-conductivity material. For high-permeability material its magnetic reluctance is much lower than the surrounding air medium so most of the magnetic line goes through the high-permeability material rather than surrounding air. For high-conductivity material the eddy current in the material can produce reverse magnetic field to achieve magnetic shielding. This paper studies the effect of the two types of shielding material on coupler for wireless EV charging and designs combination shielding made from high-permeability material and high-conductivity material. The investigation of the paper is done with the help of finite element analysis.

Inductively-Charged High-Temperature Superconductors And Methods Of Use

DOEpatents

Bromberg, Leslie

2003-09-16

The invention provides methods of charging superconducting materials and, in particular, methods of charging high-temperature superconducting materials. The methods generally involve cooling a superconducting material to a temperature below its critical temperature. Then, an external magnetic field is applied to charge the material at a nearly constant temperature. The external magnetic field first drives the superconducting material to a critical state and then penetrates into the material. When in the critical state, the superconducting material loses all the pinning ability and therefore is in the flux-flow regime. In some embodiments, a first magnetic field may be used to drive the superconducting material to the critical state and then a second magnetic field may be used to penetrate the superconducting material. When the external field or combination of external fields are removed, the magnetic field that has penetrated into the material remains trapped. The charged superconducting material may be used as solenoidal magnets, dipole magnets, or other higher order multipole magnets in many applications.

Magnetic refrigeration apparatus with heat pipes

DOEpatents

Barclay, John A.; Prenger, Jr., F. Coyne

1987-01-01

A magnetic refrigerator operating in the 4 to 20 K range utilizes heat pipes to transfer heat to and from the magnetic material at the appropriate points during the material's movement. In one embodiment circular disks of magnetic material can be interleaved with the ends of the heat pipes. In another embodiment a mass of magnetic material reciprocatingly moves between the end of the heat pipe of pipes that transmits heat from the object of cooling to the magnetic material and the end of the heat pipe or pipes that transmits heat from the magnetic material to a heat sink.

Magnetic refrigeration apparatus with heat pipes

DOEpatents

Barclay, J.A.; Prenger, F.C. Jr.

1985-10-25

A magnetic refrigerator operating in the 4 to 20 K range utilizes heat pipes to transfer heat to and from the magnetic material at the appropriate points during the material's movement. In one embodiment circular disks of magnetic material can be interleaved with the ends of the heat pipes. In another embodiment a mass of magnetic material reciprocatingly moves between the end of the heat pipe or pipes that transmits heat from the object of cooling to the magnetic material and the end of the heat pipe or pipes that transmits heat from the magnetic material to a heat sink.

High resistivity iron-based, thermally stable magnetic material for on-chip integrated inductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deligianni, Hariklia; Gallagher, William J.; Mason, Maurice

An on-chip magnetic structure includes a palladium activated seed layer and a substantially amorphous magnetic material disposed onto the palladium activated seed layer. The substantially amorphous magnetic material includes nickel in a range from about 50 to about 80 atomic % (at. %) based on the total number of atoms of the magnetic material, iron in a range from about 10 to about 50 at. % based on the total number of atoms of the magnetic material, and phosphorous in a range from about 0.1 to about 30 at. % based on the total number of atoms of the magneticmore » material. The magnetic material can include boron in a range from about 0.1 to about 5 at. % based on the total number of atoms of the magnetic material.« less

Density-Functional Theory Study of Materials and Their Properties at Non-Zero Temperature

NASA Astrophysics Data System (ADS)

Antolin, Nikolas

Density functional theory (DFT) has proven useful in providing energetic and structural data to inform higher levels of simulation as well as populate materials databases. However, DFT does not intrinsically include temperature effects that are critical to determining materials behavior in real-world applications. By considering the magnitude of critical energy differences in a system to be studied, one may select the appropriate level of additional theory with which to supplement DFT to obtain meaningful results with respect to temperature-induced behavior. This thesis details studies on three materials systems, representing three distinct levels of additional theory used in the study of thermally-induced behavior. After introducing the concepts involved in extracting thermal data from atomistics and density functional theory in chapters 1 and 2, chapter 3 details studies on a Ni-base superalloy system and its behavior in creep testing at high temperature due to planar defects. Chapters 4 and 5 detail work on thermal stabilization of BCC phases which are unstable without temperature effects and the progress in calculating the thermodynamic stability of vacancies in these and other BCC systems. Chapter 6 describes a study of thermal effects coupling to magnetism in indium antimonide (InSb), which are the result of previously unobserved coupling between phonons and magnetic field in a diamagnetic material. All three of the systems studied exhibit materials properties which are strongly temperature-dependent, but the level of theory necessary to study them varies from simple ground state calculations to consideration of the effects of single vibrational modes within the material. Since many of the approaches used and introduced here are computationally intensive and push the limits of publicly available computational resources, this thesis puts additional focus on optimizing code execution and choosing an appropriate level of theory to probe a given material system. An inappropriate level of theory can either be computationally wasteful (or unfeasible) or yield meaningless results; it is only by the inclusion of appropriate thermal effects, determined by system to be considered, that valid results can be obtained. Though much progress has been made in generalizing the approaches described in this thesis, further research will be necessary if we hope to fulfill the lofty goal of a universally applicable method of extracting thermal data from first principles in a way that guarantees valid and useful results.

Minnealloy: a new magnetic material with high saturation flux density and low magnetic anisotropy

NASA Astrophysics Data System (ADS)

Mehedi, Md; Jiang, Yanfeng; Suri, Pranav Kumar; Flannigan, David J.; Wang, Jian-Ping

2017-09-01

We are reporting a new soft magnetic material with high saturation magnetic flux density, and low magnetic anisotropy. The new material is a compound of iron, nitrogen and carbon, α‧-Fe8(NC), which has saturation flux density of 2.8  ±  0.15 T and magnetic anisotropy of 46 kJ m-3. The saturation flux density is 27% higher than pure iron, a widely used soft magnetic material. Soft magnetic materials are very important building blocks of motors, generators, inductors, transformers, sensors and write heads of hard disk. The new material will help in the miniaturization and efficiency increment of the next generation of electronic devices.

Rare-Earth-Free Permanent Magnets for Electrical Vehicle Motors and Wind Turbine Generators: Hexagonal Symmetry Based Materials Systems Mn-Bi and M-type Hexaferrite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Yang-Ki; Haskew, Timothy; Myryasov, Oleg

2014-06-05

The research we conducted focuses on the rare-earth (RE)-free permanent magnet by modeling, simulating, and synthesizing exchange coupled two-phase (hard/soft) RE-free core-shell nano-structured magnet. The RE-free magnets are made of magnetically hard core materials (high anisotropy materials including Mn-Bi-X and M-type hexaferrite) coated by soft shell materials (high magnetization materials including Fe-Co or Co). Therefore, our research helps understand the exchange coupling conditions of the core/shell magnets, interface exchange behavior between core and shell materials, formation mechanism of core/shell structures, stability conditions of core and shell materials, etc.

Progress towards an electron electric dipole moment search in Europium-Barium Titanates

NASA Astrophysics Data System (ADS)

Eckel, Stephen; Sushkov, Alexander; Lamoreaux, Steven

2012-06-01

We report on recent progress on a search for the electron's electric dipole moment (eEDM) using solid- state Eu0.5Ba0.5TiO3. This material has many desirable properties including ferroelectricity below 200 K and paramagnetism above 1.8 K. When the sample has a non-zero electric polarization, the seven unpaired 4f electrons of the Eu^2+ ions in the lattice feel a large effective electric field of order 10 MV/cm in the direction of the polarization. This causes the electron spins to align with the electric polarization and generate a magnetization, which is measured using DC SQUID magnetometers. We will detail measurements of systematic effects along with recent results toward a measurement of the eEDM.

One-dimensional nanomaterials for energy storage

NASA Astrophysics Data System (ADS)

Chen, Cheng; Fan, Yuqi; Gu, Jianhang; Wu, Liming; Passerini, Stefano; Mai, Liqiang

2018-03-01

The search for higher energy density, safer, and longer cycling-life energy storage systems is progressing quickly. One-dimensional (1D) nanomaterials have a large length-to-diameter ratio, resulting in their unique electrical, mechanical, magnetic and chemical properties, and have wide applications as electrode materials in different systems. This article reviews the latest hot topics in applying 1D nanomaterials, covering both their synthesis and their applications. 1D nanomaterials can be grouped into the categories: carbon, silicon, metal oxides, and conducting polymers, and we structure our discussion accordingly. Then, we survey the unique properties and application of 1D nanomaterials in batteries and supercapacitors, and provide comments on the progress and advantages of those systems, paving the way for a better understanding of employing 1D nanomaterials for energy storage.

Progress in NMR Studies of Liquid Ceramic Materials

NASA Astrophysics Data System (ADS)

Marzke, Robert F.; Piwowarczyk, Jeremy; Boucher, Susan; Wolf, George H.

2003-10-01

The availability of molten, levitated samples of Al-containing ceramics at temperatures of 2,000^oC and higher permits a broad range of important materials to be investigated by the powerful techniques of NMR.footnote Coutures, J-P., Massiot, D., Bessada, C., Echegut, P., Rifflet, J-C. & Taulelle F., Etude par RMN 27Al daluminates liquides dans le domaine 1600-2100 ^oC. C.R. Acad. Sci. Paris, 1990, 310, 1041. Standard measurements of chemical shift as a function of composition yield information concerning the bonding of Al and the structure of liquid phases, for both novel and well-studied refractory materials. Studies of incoherent motions in a sample, such as Al diffusion or time-dependent convective currents, may also be performed when magnetic field gradients are incorporated into the experimental NMR probe. Recent advances are reviewed, in several research areas.

TOPICAL REVIEW: First principles studies of multiferroic materials

NASA Astrophysics Data System (ADS)

Picozzi, Silvia; Ederer, Claude

2009-07-01

Multiferroics, materials where spontaneous long-range magnetic and dipolar orders coexist, represent an attractive class of compounds, which combine rich and fascinating fundamental physics with a technologically appealing potential for applications in the general area of spintronics. Ab initio calculations have significantly contributed to recent progress in this area, by elucidating different mechanisms for multiferroicity and providing essential information on various compounds where these effects are manifestly at play. In particular, here we present examples of density-functional theory investigations for two main classes of materials: (a) multiferroics where ferroelectricity is driven by hybridization or purely structural effects, with BiFeO3 as the prototype material, and (b) multiferroics where ferroelectricity is driven by correlation effects and is strongly linked to electronic degrees of freedom such as spin-, charge-, or orbital-ordering, with rare-earth manganites as prototypes. As for the first class of multiferroics, first principles calculations are shown to provide an accurate qualitative and quantitative description of the physics in BiFeO3, ranging from the prediction of large ferroelectric polarization and weak ferromagnetism, over the effect of epitaxial strain, to the identification of possible scenarios for coupling between ferroelectric and magnetic order. For the second class of multiferroics, ab initio calculations have shown that, in those cases where spin-ordering breaks inversion symmetry (e.g. in antiferromagnetic E-type HoMnO3), the magnetically induced ferroelectric polarization can be as large as a few µC cm-2. The examples presented point the way to several possible avenues for future research: on the technological side, first principles simulations can contribute to a rational materials design, aimed at identifying spintronic materials that exhibit ferromagnetism and ferroelectricity at or above room temperature. On the fundamental side, ab initio approaches can be used to explore new mechanisms for ferroelectricity by exploiting electronic correlations that are at play in transition metal oxides, and by suggesting ways to maximize the strength of these effects as well as the corresponding ordering temperatures.

Molecular Beam Epitaxial Growth of Iron Nitrides on Zinc-Blende Gallium Nitride(001)

NASA Astrophysics Data System (ADS)

Pak, Jeongihm; Lin, Wenzhi; Chinchore, Abhijit; Wang, Kangkang; Smith, Arthur R.

2008-03-01

Iron nitrides are attractive materials for their high magnetic moments, corrosion, and oxidation resistance. We present the successful epitaxial growth of iron nitride on zinc-blende gallium nitride (c-GaN) in order to develop a novel magnetic transition metal nitride/semiconductor system. First, GaN is grown on magnesium oxide (MgO) substrates having (001) orientation using rf N2-plasma molecular beam epitaxy. Then we grow FeN at substrate temperature of ˜ 210 ^oC up to a thickness of ˜ 10.5 nm. In-situ reflection high-energy electron diffraction (RHEED) is used to monitor the surface during growth. Initial results suggest that the epitaxial relationship is FeN[001] || GaN[001] and FeN[100] || GaN[100]. Work in progress is to investigate the surface using in-situ scanning tunneling microscopy (STM) to reveal the surface structure at atomic scale, as well as to explore more Fe-rich magnetic phases.

Development of scanning graphene Hall probes for magnetic microscopy

NASA Astrophysics Data System (ADS)

Schaefer, Brian T.; Wang, Lei; McEuen, Paul L.; Nowack, Katja C.

We discuss our progress on developing scanning Hall probes fabricated from hexagonal boron nitride (hBN)-encapsulated graphene, with the goal to image magnetic fields with submicron resolution. In contrast to scanning superconducting quantum interference device (SQUID) microscopy, this technique is compatible with a large applied magnetic field and not limited to cryogenic temperatures. The field sensitivity of a Hall probe depends inversely on carrier density, while the primary source of noise in the measurement is Johnson noise originating from the device resistance. hBN-encapsulated graphene demonstrates high carrier mobility at low carrier densities, therefore making it an ideal material for sensitive Hall probes. Furthermore, engineering the dielectric environment of graphene by encapsulating in hBN reduces low-frequency charge noise and disorder from the substrate. We outline our plans for adapting these devices for scanning, including characterization of the point spread function with a scanned current loop and fabrication of a deep-etched structure that enables positioning the sensitive area within 100 nanometers of the sample surface.

Tailored magnetic nanoparticles for in vitro, in vivo and in situ magnetorelaxometry

NASA Astrophysics Data System (ADS)

Pisanic, Thomas R., II

The development of novel methods of probing biological interactions is critical to the advancement of biomedical science. Recent progress in the synthesis and science of nanoscale structures has engendered a renaissance in the evolution of techniques aimed at the analysis of these interactions. The use of nanomaterials provides the researcher with access to the extended quantum behaviors of these materials and the ability to intimately interact with the fundamental subunits of biology. Magnetic materials on this size scale, such as magnetic nanoparticles (MNPs), also exhibit unique properties not available in larger structures and have likewise become of chief interest in the field of nanotechnology. Through exploitation of various synthesis techniques and parameters, the physicochemical and magnetic properties of magnetic nanoparticles can be exquisitely controlled. Magnetorelaxometry is the field of study concerned with the mechanisms of magnetic relaxation and the development of applications that capitalize upon these phenomena. The preferred instrument for the analysis of these magnetic properties is the superconducting quantum interference device (SQUID). This work focuses on the development and chemical modification of MNPs for use with this instrument and the demonstration of novel magnetorelaxometric applications in biomedicine. The basic chemical synthesis of magnetic nanoparticles is first developed and demonstrated, after which the SQUID system and the magnetic properties of a library of synthesis products are analyzed and evaluated for use in magnetorelaxometry. An in vitro assay for sepsis diagnostics is then developed based upon the conjugation of anti-Escherichia coli O157:H7 antibodies to magnetic nanoparticles and the magnetorelaxometric quantification of binding of these MNPs to the target pathogen in buffer, serum and blood. Next, parameters for the conjugation of insecticidic crystal proteins to MNPs are developed and optimized for an in vivo assay for the quantification of toxin binding in the gut of live Caenorhibditis elegans nematodes. Lastly, the concentration dependent effects of MNPs upon PC12 cells are evaluated; followed by the development of an antibody based in situ assay for the detection of tubulin using the TAT peptide for entry into live cells. The results of these assays underscore the utility of magnetorelaxometry for applications in biomedicine.

Serial Magnetic Resonance Imaging in Active Surveillance of Prostate Cancer: Incremental Value.

PubMed

Felker, Ely R; Wu, Jason; Natarajan, Shyam; Margolis, Daniel J; Raman, Steven S; Huang, Jiaoti; Dorey, Fred; Marks, Leonard S

2016-05-01

We assessed whether changes in serial multiparametric magnetic resonance imaging can help predict the pathological progression of prostate cancer in men on active surveillance. A retrospective cohort study was conducted of 49 consecutive men with Gleason 6 prostate cancer who underwent multiparametric magnetic resonance imaging at baseline and again more than 6 months later, each followed by a targeted prostate biopsy, between January 2011 and May 2015. We evaluated whether progression on multiparametric magnetic resonance imaging (an increase in index lesion suspicion score, increase in index lesion volume or decrease in index lesion apparent diffusion coefficient) could predict pathological progression (Gleason 3 + 4 or greater on subsequent biopsy, in systematic or targeted cores). Diagnostic performance of multiparametric magnetic resonance imaging was determined with and without clinical data using a binary logistic regression model. The mean interval between baseline and followup multiparametric magnetic resonance imaging was 28.3 months (range 11 to 43). Pathological progression occurred in 19 patients (39%). The sensitivity, specificity, positive predictive value and negative predictive value of multiparametric magnetic resonance imaging was 37%, 90%, 69% and 70%, respectively. Area under the receiver operating characteristic curve was 0.63. A logistic regression model using clinical information (maximum cancer core length greater than 3 mm on baseline biopsy or a prostate specific antigen density greater than 0.15 ng/ml(2) at followup biopsy) had an AUC of 0.87 for predicting pathological progression. The addition of serial multiparametric magnetic resonance imaging data significantly improved the AUC to 0.91 (p=0.044). Serial multiparametric magnetic resonance imaging adds incremental value to prostate specific antigen density and baseline cancer core length for predicting Gleason 6 upgrading in men on active surveillance. Copyright © 2016 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Computational methods for 2D materials: discovery, property characterization, and application design.

PubMed

Paul, J T; Singh, A K; Dong, Z; Zhuang, H; Revard, B C; Rijal, B; Ashton, M; Linscheid, A; Blonsky, M; Gluhovic, D; Guo, J; Hennig, R G

2017-11-29

The discovery of two-dimensional (2D) materials comes at a time when computational methods are mature and can predict novel 2D materials, characterize their properties, and guide the design of 2D materials for applications. This article reviews the recent progress in computational approaches for 2D materials research. We discuss the computational techniques and provide an overview of the ongoing research in the field. We begin with an overview of known 2D materials, common computational methods, and available cyber infrastructures. We then move onto the discovery of novel 2D materials, discussing the stability criteria for 2D materials, computational methods for structure prediction, and interactions of monolayers with electrochemical and gaseous environments. Next, we describe the computational characterization of the 2D materials' electronic, optical, magnetic, and superconducting properties and the response of the properties under applied mechanical strain and electrical fields. From there, we move on to discuss the structure and properties of defects in 2D materials, and describe methods for 2D materials device simulations. We conclude by providing an outlook on the needs and challenges for future developments in the field of computational research for 2D materials.

System and method for manipulating domain pinning and reversal in ferromagnetic materials

DOEpatents

Silevitch, Daniel M.; Rosenbaum, Thomas F.; Aeppli, Gabriel

2013-10-15

A method for manipulating domain pinning and reversal in a ferromagnetic material comprises applying an external magnetic field to a uniaxial ferromagnetic material comprising a plurality of magnetic domains, where each domain has an easy axis oriented along a predetermined direction. The external magnetic field is applied transverse to the predetermined direction and at a predetermined temperature. The strength of the magnetic field is varied at the predetermined temperature, thereby isothermally regulating pinning of the domains. A magnetic storage device for controlling domain dynamics includes a magnetic hard disk comprising a uniaxial ferromagnetic material, a magnetic recording head including a first magnet, and a second magnet. The ferromagnetic material includes a plurality of magnetic domains each having an easy axis oriented along a predetermined direction. The second magnet is positioned adjacent to the magnetic hard disk and is configured to apply a magnetic field transverse to the predetermined direction.

Magnetic shielding

DOEpatents

Kerns, J.A.; Stone, R.R.; Fabyan, J.

1987-10-06

A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient magnetic field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines. 3 figs.

Magnetic shielding

DOEpatents

Kerns, John A.; Stone, Roger R.; Fabyan, Joseph

1987-01-01

A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient magnetic field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines.

Manifestations of Kitaev physics in thermodynamic properties of hexagonal iridates and α-RuCl3

NASA Astrophysics Data System (ADS)

Tsirlin, Alexander

Kitaev model is hard to achieve in real materials. Best candidates available so far are hexagonal iridates M2IrO3 (M = Li and Na) and the recently discovered α-RuCl3 featuring hexagonal layers coupled by weak van der Waals bonding. I will review recent progress in crystal growth of these materials and compare their thermodynamic properties. Both hexagonal iridates and α-RuCl3 feature highly anisotropic Curie-Weiss temperatures that not only differ in magnitude but also change sign depending on the direction of the applied magnetic field. Néel temperatures are largely suppressed compared to the energy scale of the Curie-Weiss temperatures. These experimental observations will be linked to features of the electronic structure and to structural peculiarities associated with deviations from the ideal hexagonal symmetry. I will also discuss how the different nature of ligand atoms affects electronic structure and magnetic superexchange. This work has been done in collaboration with M. Majumder, M. Schmidt, M. Baenitz, F. Freund, and P. Gegenwart.

Current advances in lanthanide ion (Ln(3+))-based upconversion nanomaterials for drug delivery.

PubMed

Yang, Dongmei; Ma, Ping'an; Hou, Zhiyou; Cheng, Ziyong; Li, Chunxia; Lin, Jun

2015-03-21

Lanthanide ion (Ln(3+))-based upconversion nano/micromaterials that emit higher-energy visible light when excited by low-energy NIR light have aroused considerable attention in the forefront of materials science and biomedical fields, which stems from their unique optical and chemical properties including minimum photodamage to living organisms, low autofluorescence, high signal-to-noise ratio and detection sensitivity, and high penetration depth in biological or environmental samples. Thus, Ln(3+)-based upconversion materials are rising new stars and are quickly emerging as potential candidates to revolutionize novel biomedical applications. In this review article, we mainly focus on the recent progress in various chemical syntheses of Ln(3+)-based upconversion nanomaterials, with special emphasis on their application in stimuli-response controlled drug release and subsequent therapy. Functional groups that are introduced into the stimuli-responsive system can respond to external triggers, such as pH, temperature, light, and even magnetic fields, which can regulate the movement of the pharmaceutical cargo and release the drug at a desired time and in a desired area. This is crucial to boost drug efficacy in cancer treatment while minimizing the side effects of cytotoxic drugs. Many multifunctional (magnetic/upconversion luminescence and porous) composite materials based on Ln(3+) have been designed for controlled drug delivery and multimodal bioimaging. Finally, the challenges and future opportunities for Ln(3+)-based upconversion materials are discussed.

Metamaterial-inspired silicon nanophotonics

NASA Astrophysics Data System (ADS)

Staude, Isabelle; Schilling, Jörg

2017-04-01

The prospect of creating metamaterials with optical properties greatly exceeding the parameter space accessible with natural materials has been inspiring intense research efforts in nanophotonics for more than a decade. Following an era of plasmonic metamaterials, low-loss dielectric nanostructures have recently moved into the focus of metamaterial-related research. This development was mainly triggered by the experimental observation of electric and magnetic multipolar Mie-type resonances in high-refractive-index dielectric nanoparticles. Silicon in particular has emerged as a popular material choice, due to not only its high refractive index and very low absorption losses in the telecom spectral range, but also its paramount technological relevance. This Review overviews recent progress on metamaterial-inspired silicon nanostructures, including Mie-resonant and off-resonant regimes.

TRAVELING WAVE PYROTRON

DOEpatents

Post, R.F.

1963-06-11

The invention relates to a pyrotron, i.e., magnetic mirror device, designed for continuous operation in producing a high-temperature fusion reaction plasma and for directly converting the plasma energy into electrical power. The device utilizes a system in which an axially symmetric magnetic field is produced and transports plasma through a first zone of progressively rising field intensity, a second reaction zone of slowly increasing intensity, and thenceforth through a third zone of progressively decreasing intensity wherein the plasma expands against the magnetic field thereby producing electrical current in magnetic field generating solenoids associated with said third zone. (AEC)

Computational methods for 2D materials: discovery, property characterization, and application design

NASA Astrophysics Data System (ADS)

Paul, J. T.; Singh, A. K.; Dong, Z.; Zhuang, H.; Revard, B. C.; Rijal, B.; Ashton, M.; Linscheid, A.; Blonsky, M.; Gluhovic, D.; Guo, J.; Hennig, R. G.

2017-11-01

The discovery of two-dimensional (2D) materials comes at a time when computational methods are mature and can predict novel 2D materials, characterize their properties, and guide the design of 2D materials for applications. This article reviews the recent progress in computational approaches for 2D materials research. We discuss the computational techniques and provide an overview of the ongoing research in the field. We begin with an overview of known 2D materials, common computational methods, and available cyber infrastructures. We then move onto the discovery of novel 2D materials, discussing the stability criteria for 2D materials, computational methods for structure prediction, and interactions of monolayers with electrochemical and gaseous environments. Next, we describe the computational characterization of the 2D materials’ electronic, optical, magnetic, and superconducting properties and the response of the properties under applied mechanical strain and electrical fields. From there, we move on to discuss the structure and properties of defects in 2D materials, and describe methods for 2D materials device simulations. We conclude by providing an outlook on the needs and challenges for future developments in the field of computational research for 2D materials.

A magnetic-piezoelectric smart material-structure sensing three axis DC and AC magnetic-fields

NASA Astrophysics Data System (ADS)

Hung, Chiao-Fang; Chen, Chin-Chung; Yeh, Po-Chen; Chen, Po-Wen; Chung, Tien-Kan

2017-12-01

In this paper, we demonstrate a smart material-structure can sense not only three-axis AC magnetic-fields but also three-axis DC magnetic-fields. Under x-axis and z-axis AC magnetic field ranging from 0.2 to 3.2 gauss, sensing sensitivity of the smart material-structure stimulated at resonant frequency is approximate 8.79 and 2.80 mV/gauss, respectively. In addition, under x-axis and z-axis DC magnetic fields ranging from 2 to 12 gauss, the sensitivity of the smart material-structure is 1.24-1.54 and 1.25-1.41 mV/gauss, respectively. In addition, under x-axis and z-axis DC magnetic fields ranging from 12 to 20 gauss, the sensitivity of the smart material-structure is 5.17-6.2 and 3.97-4.57 mV/gauss, respectively. These experimental results show that the smart material-structure successfully achieves three-axis DC and AC magnetic sensing as we designed. Furthermore, we also compare the results of the AC and DC magnetic-field sensing to investigate discrepancies. Finally, when applying composite magnetic-fields to the smart material-structure, the smart material-structure shows decent outputs as expected (consistent to the sensing principle). In the future, we believe the smart material-structure capable of sensing AC and DC magnetic fields will have more applications than conventional structures capable of sensing only DC or AC magnetic field. Thus, the smart material-structure will be an important design reference for future magnetic-field sensing technologies.

Use of magnetic carbon composites from renewable resource materials for oil spill clean up and recovery

DOEpatents

Viswanathan, Tito

2015-10-27

A method of separating a liquid hydrocarbon material from a body of water, includes: (a) mixing magnetic carbon-metal nanocomposites with a liquid hydrocarbon material dispersed in a body of water to allow the magnetic carbon-metal nanocomposites each to be adhered by the liquid hydrocarbon material to form a mixture; (b) applying a magnetic force to the mixture to attract the magnetic carbon-metal nanocomposites each adhered by the liquid hydrocarbon material; and (c) removing the body of water from the magnetic carbon-metal nanocomposites each adhered by the liquid hydrocarbon material while maintaining the applied magnetic force. The magnetic carbon-metal nanocomposites is formed by subjecting one or more metal lignosulfonates or metal salts to microwave radiation, in presence of lignin/derivatives either in presence of alkali or a microwave absorbing material, for a period of time effective to allow the carbon-metal nanocomposites to be formed.

Self-organization in precipitation reactions far from the equilibrium

PubMed Central

Nakouzi, Elias; Steinbock, Oliver

2016-01-01

Far from the thermodynamic equilibrium, many precipitation reactions create complex product structures with fascinating features caused by their unusual origins. Unlike the dissipative patterns in other self-organizing reactions, these features can be permanent, suggesting potential applications in materials science and engineering. We review four distinct classes of precipitation reactions, describe similarities and differences, and discuss related challenges for theoretical studies. These classes are hollow micro- and macrotubes in chemical gardens, polycrystalline silica carbonate aggregates (biomorphs), Liesegang bands, and propagating precipitation-dissolution fronts. In many cases, these systems show intricate structural hierarchies that span from the nanometer scale into the macroscopic world. We summarize recent experimental progress that often involves growth under tightly regulated conditions by means of wet stamping, holographic heating, and controlled electric, magnetic, or pH perturbations. In this research field, progress requires mechanistic insights that cannot be derived from experiments alone. We discuss how mesoscopic aspects of the product structures can be modeled by reaction-transport equations and suggest important targets for future studies that should also include materials features at the nanoscale. PMID:27551688

Recent Progress on the magnetic turbulence experiment at the Bryn Mawr Plasma Laboratory

NASA Astrophysics Data System (ADS)

Schaffner, D. A.; Cartagena-Sanchez, C. A.; Johnson, H. K.; Fahim, L. E.; Fiedler-Kawaguchi, C.; Douglas-Mann, E.

2017-10-01

Recent progress is reported on the construction, implementation and testing of the magnetic turbulence experiment at the Bryn Mawr Plasma Laboratory (BMPL). The experiment at the BMPL consists of an ( 300 μs) long coaxial plasma gun discharge that injects magnetic helicity into a flux-conserving chamber in a process akin to sustained slow-formation of spheromaks. A 24cm by 2m cylindrical chamber has been constructed with a high density axial port array to enable detailed simultaneous spatial measurements of magnetic and plasma fluctuations. Careful positioning of the magnetic structure produced by the three separately pulsed coils (one internal, two external) are preformed to optimize for continuous injection of turbulent magnetized plasma. High frequency calibration of magnetic probes is also underway using a power amplifier.

Force sensor using changes in magnetic flux

NASA Technical Reports Server (NTRS)

Pickens, Herman L. (Inventor); Richard, James A. (Inventor)

2012-01-01

A force sensor includes a magnetostrictive material and a magnetic field generator positioned in proximity thereto. A magnetic field is induced in and surrounding the magnetostrictive material such that lines of magnetic flux pass through the magnetostrictive material. A sensor positioned in the vicinity of the magnetostrictive material measures changes in one of flux angle and flux density when the magnetostrictive material experiences an applied force that is aligned with the lines of magnetic flux.

Magnetic shielding

DOEpatents

Kerns, J.A.; Stone, R.R.; Fabyan, J.

1985-02-12

A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines.

Progress in the Field of Constructing Near-Infrared Light-Responsive Drug Delivery Platforms.

PubMed

Zhou, Fang; Wang, Hanjie; Chang, Jin

2016-03-01

Stimuli-responsive materials have taken replace of traditional drug carriers due to their ability to achieve controlled release of their encapsulated contents. A variety of sensitive materials, such as polymers that respond to pH, light, and magnetic fields, are widely used to construct drug carriers, and achieved good results. Specifically, near-infrared light (NIR) responsive materials are of particular interest in drug delivery, as NIR can penetrate body tissue and is minimally absorbed by the body's water and hemoglobin and is less harmful to healthy cells than UV or visible light. Thus, the near-infrared excitation drug delivery systems (NIRDDSs) have some essential advantages just like being efficient to kill tumor cells, accurate to achieve the tumor sites and less damage to human body. Also, in the process of building the carriers, we may achieve a combination of controlled release chemotherapy, photothermal therapy (PTT) or photodynamic therapy (PDT). In addition, besides utilizing as drug delivery platforms, some carriers can achieve multifunctional tumor diagnosis and treatment, such as magnetic resonance imaging, optical imaging, drug carriers and PTT. In this review, based on the mechanism of NIR, we highlight diverse near-infrared light-responsive drug delivery platforms and recent advances in the development of NIRDDSs for cancer therapy primarily.

Longitudinal Evaluation of Muscle Composition Using Magnetic Resonance in 4 Boys With Duchenne Muscular Dystrophy: Case Series.

PubMed

Senesac, Claudia R; Lott, Donovan J; Forbes, Sean C; Mathur, Sunita; Arpan, Ishu; Senesac, Emily S; Walter, Glenn A; Vandenborne, Krista

2015-07-01

Duchenne muscular dystrophy (DMD), an inherited recessive X chromosome-linked disease, is the most severe childhood form of muscular dystrophy. Boys with DMD experience muscle loss, with infiltration of intramuscular fat into muscles. This case series describes the progression of DMD in boys using magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS). Magnetic resonance results are then compared with an established functional timed test. Four boys with DMD and 4 healthy age-matched controls were chosen from a larger cohort. Boys with DMD were assessed at 4 time points over 2 years, with controls assessed at baseline only. Progression of the disease was documented by assessing the plantar flexors using MRI and MRS techniques and by assessing ambulation using the 30-Foot Fast Walk Test. Transverse relaxation time (T2) values were elevated in all boys with DMD at baseline. The lipid ratio increased rapidly as the disease progressed in 2 boys. Discrete changes in T2 in the other 2 boys with DMD indicated a slower disease progression. Magnetic resonance imaging and MRS allowed monitoring of the disease over all time periods regardless of ambulation status. The magnetic resonance data were collected with 2 different magnets at 2 different field strengths (1.5 and 3.0 T). Although we corrected for this difference, care must be taken in interpreting data when different image collection systems are used. This was a case series of 4 boys with DMD taken from a larger cohort study. Magnetic resonance imaging and MRS are objective, noninvasive techniques for measuring muscle pathology and can be used to detect discrete changes in both people who are ambulatory and those who are nonambulatory. These techniques should be considered when monitoring DMD progression and assessing efficacy of therapeutic interventions. © 2015 American Physical Therapy Association.

Longitudinal Evaluation of Muscle Composition Using Magnetic Resonance in 4 Boys With Duchenne Muscular Dystrophy: Case Series

PubMed Central

Lott, Donovan J.; Forbes, Sean C.; Mathur, Sunita; Arpan, Ishu; Senesac, Emily S.; Walter, Glenn A.; Vandenborne, Krista

2015-01-01

Background Duchenne muscular dystrophy (DMD), an inherited recessive X chromosome-linked disease, is the most severe childhood form of muscular dystrophy. Boys with DMD experience muscle loss, with infiltration of intramuscular fat into muscles. Objectives This case series describes the progression of DMD in boys using magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS). Magnetic resonance results are then compared with an established functional timed test. Methods Four boys with DMD and 4 healthy age-matched controls were chosen from a larger cohort. Boys with DMD were assessed at 4 time points over 2 years, with controls assessed at baseline only. Progression of the disease was documented by assessing the plantar flexors using MRI and MRS techniques and by assessing ambulation using the 30-Foot Fast Walk Test. Results Transverse relaxation time (T2) values were elevated in all boys with DMD at baseline. The lipid ratio increased rapidly as the disease progressed in 2 boys. Discrete changes in T2 in the other 2 boys with DMD indicated a slower disease progression. Magnetic resonance imaging and MRS allowed monitoring of the disease over all time periods regardless of ambulation status. Limitations The magnetic resonance data were collected with 2 different magnets at 2 different field strengths (1.5 and 3.0 T). Although we corrected for this difference, care must be taken in interpreting data when different image collection systems are used. This was a case series of 4 boys with DMD taken from a larger cohort study. Conclusions Magnetic resonance imaging and MRS are objective, noninvasive techniques for measuring muscle pathology and can be used to detect discrete changes in both people who are ambulatory and those who are nonambulatory. These techniques should be considered when monitoring DMD progression and assessing efficacy of therapeutic interventions. PMID:25592189

Quadrupole magnetic field-flow fractionation: A novel technique for the characterization of magnetic particles

NASA Astrophysics Data System (ADS)

Carpino, Francesca

In the last few decades, the development and use of nanotechnology has become of increasing importance. Magnetic nanoparticles, because of their unique properties, have been employed in many different areas of application. They are generally made of a core of magnetic material coated with some other material to stabilize them and to help disperse them in suspension. The unique feature of magnetic nanoparticles is their response to a magnetic field. They are generally superparamagnetic, in which case they become magnetized only in a magnetic field and lose their magnetization when the field is removed. It is this feature that makes them so useful for drug targeting, hyperthermia and bioseparation. For many of these applications, the synthesis of uniformly sized magnetic nanoparticles is of key importance because their magnetic properties depend strongly on their dimensions. Because of the difficulty of synthesizing monodisperse particulate materials, a technique capable of characterizing the magnetic properties of polydisperse samples is of great importance. Quadrupole magnetic field-flow fractionation (MgFFF) is a technique capable of fractionating magnetic particles based on their content of magnetite or other magnetic material. In MgFFF, the interplay of hydrodynamic and magnetic forces separates the particles as they are carried along a separation channel. Since the magnetic field and the gradient in magnetic field acting on the particles during their migration are known, it is possible to calculate the quantity of magnetic material in the particles according to their time of emergence at the channel outlet. Knowing the magnetic properties of the core material, MgFFF can be used to determine both the size distribution and the mean size of the magnetic cores of polydisperse samples. When magnetic material is distributed throughout the volume of the particles, the derived data corresponds to a distribution in equivalent spherical diameters of magnetic material in the particles. MgFFF is unique in its ability to characterize the distribution in magnetic properties of a particulate sample. This knowledge is not only of importance to the optimization and quality control of particle preparation. It is also of great importance in modeling magnetic cell separation, drug targeting, hyperthermia, and other areas of application.

Study of Magnetic Damping Effect on Convection and Solidification Under G-Jitter Conditions

NASA Technical Reports Server (NTRS)

Li, Ben Q.; deGroh, H. C., III

1999-01-01

As shown by NASA resources dedicated to measuring residual gravity (SAMS and OARE systems), g-jitter is a critical issue affecting space experiments on solidification processing of materials. This study aims to provide, through extensive numerical simulations and ground based experiments, an assessment of the use of magnetic fields in combination with microgravity to reduce the g-jitter induced convective flows in space processing systems. We have so far completed asymptotic analyses based on the analytical solutions for g-jitter driven flow and magnetic field damping effects for a simple one-dimensional parallel plate configuration, and developed both 2-D and 3-D numerical models for g-jitter driven flows in simple solidification systems with and without presence of an applied magnetic field. Numerical models have been checked with the analytical solutions and have been applied to simulate the convective flows and mass transfer using both synthetic g-jitter functions and the g-jitter data taken from space flight. Some useful findings have been obtained from the analyses and the modeling results. Some key points may be summarized as follows: (1) the amplitude of the oscillating velocity decreases at a rate inversely proportional to the g-jitter frequency and with an increase in the applied magnetic field; (2) the induced flow approximately oscillates at the same frequency as the affecting g-jitter, but out of a phase angle; (3) the phase angle is a complicated function of geometry, applied magnetic field, temperature gradient and frequency; (4) g-jitter driven flows exhibit a complex fluid flow pattern evolving in time; (5) the damping effect is more effective for low frequency flows; and (6) the applied magnetic field helps to reduce the variation of solutal distribution along the solid-liquid interface. Work in progress includes numerical simulations and ground-based measurements. Both 2-D and 3-D numerical simulations are being continued to obtain further information on g-jitter driven flows and magnetic field effects. A physical model for ground-based measurements is completed and some measurements of the oscillating convection are being taken on the physical model. The comparison of the measurements with numerical simulations is in progress. Additional work planned in the project will also involve extending the 2-D numerical model to include the solidification phenomena with the presence of both g-jitter and magnetic fields.

High magnetic field processing of liquid crystalline polymers

DOEpatents

Smith, M.E.; Benicewicz, B.C.; Douglas, E.P.

1998-11-24

A process of forming bulk articles of oriented liquid crystalline thermoset material, the material characterized as having an enhanced tensile modulus parallel to orientation of an applied magnetic field of at least 25 percent greater than said material processed in the absence of a magnetic field, by curing a liquid crystalline thermoset precursor within a high strength magnetic field of greater than about 2 Tesla, is provided, together with a resultant bulk article of a liquid crystalline thermoset material, said material processed in a high strength magnetic field whereby said material is characterized as having a tensile modulus parallel to orientation of said field of at least 25 percent greater than said material processed in the absence of a magnetic field.

High magnetic field processing of liquid crystalline polymers

DOEpatents

Smith, Mark E.; Benicewicz, Brian C.; Douglas, Elliot P.

1998-01-01

A process of forming bulk articles of oriented liquid crystalline thermoset material, the material characterized as having an enhanced tensile modulus parallel to orientation of an applied magnetic field of at least 25 percent greater than said material processed in the absence of a magnetic field, by curing a liquid crystalline thermoset precursor within a high strength magnetic field of greater than about 2 Tesla, is provided, together with a resultant bulk article of a liquid crystalline thermoset material, said material processed in a high strength magnetic field whereby said material is characterized as having a tensile modulus parallel to orientation of said field of at least 25 percent greater than said material processed in the absence of a magnetic field.

Multifunctional nanocrystals

DOEpatents

Klimov, Victor I.; Hollingsworth, Jennifer A.; Crooker, Scott A.; Kim, Hyungrak

2010-06-22

Multifunctional nanocomposites are provided including a core of either a magnetic material or an inorganic semiconductor, and, a shell of either a magnetic material or an inorganic semiconductor, wherein the core and the shell are of differing materials, such multifunctional nanocomposites having multifunctional properties including magnetic properties from the magnetic material and optical properties from the inorganic semiconductor material. Various applications of such multifunctional nanocomposites are also provided.

Fusion Energy Division progress report, 1 January 1990--31 December 1991

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheffield, J.; Baker, C.C.; Saltmarsh, M.J.

1994-03-01

The Fusion Program of the Oak Ridge National Laboratory (ORNL), a major part of the national fusion program, encompasses nearly all areas of magnetic fusion research. The program is directed toward the development of fusion as an economical and environmentally attractive energy source for the future. The program involves staff from ORNL, Martin Marietta Energy systems, Inc., private industry, the academic community, and other fusion laboratories, in the US and abroad. Achievements resulting from this collaboration are documented in this report, which is issued as the progress report of the ORNL Fusion Energy Division; it also contains information from componentsmore » for the Fusion Program that are external to the division (about 15% of the program effort). The areas addressed by the Fusion Program include the following: experimental and theoretical research on magnetic confinement concepts; engineering and physics of existing and planned devices, including remote handling; development and testing of diagnostic tools and techniques in support of experiments; assembly and distribution to the fusion community of databases on atomic physics and radiation effects; development and testing of technologies for heating and fueling fusion plasmas; development and testing of superconducting magnets for containing fusion plasmas; development and testing of materials for fusion devices; and exploration of opportunities to apply the unique skills, technology, and techniques developed in the course of this work to other areas (about 15% of the Division`s activities). Highlights from program activities during 1990 and 1991 are presented.« less

The Features of Self-Assembling Organic Bilayers Important to the Formation of Anisotropic Inorganic Materials in Microgravity Conditions

NASA Technical Reports Server (NTRS)

Talham, Daniel R.; Adair, James H.

1999-01-01

There is a growing need for inorganic anisotropic particles in a variety of materials science applications. Structural, optical, and electrical properties can be greatly augmented by the fabrication of composite materials with anisotropic microstructures or with anisotropic particles uniformly dispersed in an isotropic matrix. Examples include structural composites, magnetic and optical recording media, photographic film, certain metal and ceramic alloys, and display technologies including flat panel displays. While considerable progress has been made toward developing an understanding of the synthesis of powders composed of monodispersed, spherical particles, these efforts have not been transferred to the synthesis of anisotropic nanoparticles. The major objective of the program is to develop a fundamental understanding of the growth of anisotropic particles at organic templates, with emphasis on the chemical and structural aspects of layered organic assemblies that contribute to the formation of anisotropic inorganic particles.

Nanoscale solid-state cooling: a review.

PubMed

Ziabari, Amirkoushyar; Zebarjadi, Mona; Vashaee, Daryoosh; Shakouri, Ali

2016-09-01

The recent developments in nanoscale solid-state cooling are reviewed. This includes both theoretical and experimental studies of different physical concepts, as well as nanostructured material design and device configurations. We primarily focus on thermoelectric, thermionic and thermo-magnetic coolers. Particular emphasis is given to the concepts based on metal-semiconductor superlattices, graded materials, non-equilibrium thermoelectric devices, Thomson coolers, and photon assisted Peltier coolers as promising methods for efficient solid-state cooling. Thermomagnetic effects such as magneto-Peltier and Nernst-Ettingshausen cooling are briefly described and recent advances and future trends in these areas are reviewed. The ongoing progress in solid-state cooling concepts such as spin-calorimetrics, electrocalorics, non-equilibrium/nonlinear Peltier devices, superconducting junctions and two-dimensional materials are also elucidated and practical achievements are reviewed. We explain the thermoreflectance thermal imaging microscopy and the transient Harman method as two unique techniques developed for characterization of thermoelectric microrefrigerators. The future prospects for solid-state cooling are briefly summarized.

Static and Dynamic Electron Microscopy Investigations at the Atomic and Ultrafast Scales

NASA Astrophysics Data System (ADS)

Suri, Pranav Kumar

Advancements in the electron microscopy capabilities - aberration-corrected imaging, monochromatic spectroscopy, direct-electron detectors - have enabled routine visualization of atomic-scale processes with millisecond temporal resolutions in this decade. This, combined with progress in the transmission electron microscopy (TEM) specimen holder technology and nanofabrication techniques, allows comprehensive experiments on a wide range of materials in various phases via in situ methods. The development of ultrafast (sub-nanosecond) time-resolved TEM with ultrafast electron microscopy (UEM) has further pushed the envelope of in situ TEM to sub-nanosecond temporal resolution while maintaining sub-nanometer spatial resolution. A plethora of materials phenomena - including electron-phonon coupling, phonon transport, first-order phase transitions, bond rotation, plasmon dynamics, melting, and dopant atoms arrangement - are not yet clearly understood and could be benefitted with the current in situ TEM capabilities having atomic-level and ultrafast precision. Better understanding of these phenomena and intrinsic material dynamics (e.g. how phonons propagate in a material, what time-scales are involved in a first-order phase transition, how fast a material melts, where dopant atoms sit in a crystal) in new-generation and technologically important materials (e.g. two-dimensional layered materials, semiconductor and magnetic devices, rare-earth-element-free permanent magnets, unconventional superconductors) could bring a paradigm shift in their electronic, structural, magnetic, thermal and optical applications. Present research efforts, employing cutting-edge static and dynamic in situ electron microscopy resources at the University of Minnesota, are directed towards understanding the atomic-scale crystallographic structural transition and phonon transport in an iron-pnictide parent compound LaFeAsO, studying the mechanical stability of fast moving hard-drive heads in heat-assisted magnetic recording (HAMR) technology, exploring the possibility of ductile ceramics in magnesium oxide (MgO) nanomaterials, and revealing the atomic-structure of newly discovered rare-earth-element-free iron nitride (FeN) magnetic materials. Via atomic-resolution imaging and electron diffraction coupled with in situ TEM cooling on LaFeAsO, it was found that additional effects not related to the structural transition, namely dynamical scattering and electron channeling, can give signatures reminiscent of those typically associated with the symmetry change. UEM studies on LaFeAsO revealed direct, real-space imaging of the emergence and evolution of acoustic phonons and resolved dispersion behavior during propagation and scattering. Via UEM bright-field imaging, megahertz vibrational frequencies were observed upon laser-illumination in TEM specimens made out of HAMR devices which could be detrimental to their long-term thermal and structural reliability. Compression testing of 100-350 nm single-crystal MgO nanocubes shows size-dependent stresses and engineering strains of 4-13.8 GPa and 0.046-0.221 respectively at the first signs of yield accompanied by an absence of brittle fracture, which is a significant increase in plasticity of a brittle ceramic material. Atomic-scale characterization of FeN phases show that it is possible to detect interstitial locations of low atomic-number nitrogen atoms in iron crystal and hints at a development of novel routes (without involving rare-earth elements) for bulk permanent magnet synthesis.

Progress on Magnetism in Massive Stars (MiMeS)

NASA Astrophysics Data System (ADS)

Neiner, C.; Alecian, E.; Mathis, S.

2011-12-01

We present the MiMeS project, which aims at studying all aspects of magnetism in massive stars to understand their characteristics, origin, incidence, evolution, and impact on other physical processes. We show examples of recent observational results obtained within this project on pulsating B stars (β Cephei and SPB stars) as well as Herbig Ae/Be stars. Recent theoretical progress obtained within MiMeS on the configuration and stability of magnetic fields is also summarized.

Mapping of Students’ Learning Progression Based on Mental Model in Magnetic Induction Concepts

NASA Astrophysics Data System (ADS)

Hamid, R.; Pabunga, D. B.

2017-09-01

The progress of student learning in a learning process has not been fully optimally observed by the teacher. The concept being taught is judged only at the end of learning as a product of thinking, and does not assess the mental processes that occur in students’ thinking. Facilitating students’ thinking through new phenomena can reveal students’ variation in thinking as a mental model of a concept, so that students who are assimilative and or accommodative can be identified in achieving their equilibrium of thought as well as an indicator of progressiveness in the students’ thinking stages. This research data is obtained from the written documents and interviews of students who were learned about the concept of magnetic induction through Constructivist Teaching Sequences (CTS) models. The results of this study indicate that facilitating the students’ thinking processes on the concept of magnetic induction contributes to increasing the number of students thinking within the "progressive change" category, and it can be said that the progress of student learning is more progressive after their mental models were facilitated through a new phenomena by teacher.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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

Application peculiarities of magnetic materials for protection from magnetic fields

NASA Astrophysics Data System (ADS)

Wai, P.; Dmitrenko, V.; Grabchikov, S.; Vlasik, K.; Novikov, A.; Petrenko, D.; Trukhanov, V.; Ulin, S.; Uteshev, Z.; Chernysheva, V.; Shustov, A.

2016-02-01

In different materials for magnetic shields, the maximum permeability is achieved for different values of the magnetic field. This determines the choice of material. So for protection from magnetic fields strength of 10 - 150 A/m it is advisable to apply the amorphous ribbon 84KXCP. For stronger fields (more than 400 A/m) it is recommended to use MFS based on Ni20Fe80. Use of these materials allows creating an effective shield working in a wide range of magnetic field strengths.

Use of magnetic carbon composites from renewable resource materials for oil spill clean up and recovery

DOEpatents

Viswanathan, Tito

2014-02-11

A method for separating a liquid hydrocarbon material from a body of water. In one embodiment, the method includes the steps of mixing a plurality of magnetic carbon-metal nanocomposites with a liquid hydrocarbon material dispersed in a body of water to allow the plurality of magnetic carbon-metal nanocomposites each to be adhered by an amount of the liquid hydrocarbon material to form a mixture, applying a magnetic force to the mixture to attract the plurality of magnetic carbon-metal nanocomposites each adhered by an amount of the liquid hydrocarbon material, and removing said plurality of magnetic carbon-metal nanocomposites each adhered by an amount of the liquid hydrocarbon material from said body of water while maintaining the applied magnetic force, wherein the plurality of magnetic carbon-metal nanocomposites is formed by subjecting one or more metal lignosulfonates or metal salts to microwave radiation, in presence of lignin/derivatives either in presence of alkali or a microwave absorbing material.

Accelerating the discovery of hidden two-dimensional magnets using machine learning and first principle calculations

NASA Astrophysics Data System (ADS)

Miyazato, Itsuki; Tanaka, Yuzuru; Takahashi, Keisuke

2018-02-01

Two-dimensional (2D) magnets are explored in terms of data science and first principle calculations. Machine learning determines four descriptors for predicting the magnetic moments of 2D materials within reported 216 2D materials data. With the trained machine, 254 2D materials are predicted to have high magnetic moments. First principle calculations are performed to evaluate the predicted 254 2D materials where eight undiscovered stable 2D materials with high magnetic moments are revealed. The approach taken in this work indicates that undiscovered materials can be surfaced by utilizing data science and materials data, leading to an innovative way of discovering hidden materials.

Nanodevices for spintronics and methods of using same

DOEpatents

Zaliznyak, Igor; Tsvelik, Alexei; Kharzeev, Dmitri

2013-02-19

Graphene magnet multilayers (GMMs) are employed to facilitate development of spintronic devices. The GMMs can include a sheet of monolayer (ML) or few-layer (FL) graphene in contact with a magnetic material, such as a ferromagnetic (FM) or an antiferromagnetic material. Electrode terminals can be disposed on the GMMs to be in electrical contact with the graphene. A magnetic field effect is induced in the graphene sheet based on an exchange magnetic field resulting from a magnetization of the magnetic material which is in contact with graphene. Electrical characteristics of the graphene can be manipulated based on the magnetization of the magnetic material in the GMM.

Nanomodified composite magnetic materials and their molding technologies

NASA Astrophysics Data System (ADS)

Timoshkov, I.; Gao, Q.; Govor, G.; Sakova, A.; Timoshkov, V.; Vetcher, A.

2018-05-01

Advanced electro-magnetic machines and systems require new materials with improved properties. Heterogeneous 3D nanomodified soft magnetic materials could be efficiently applied. Multistage technology of iron particle surface nanomodification by sequential oxidation and Si-organic coatings will be reported. The thickness of layers is 0.5-5 nm. Compaction and annealing are the final steps of magnetic parts and components shaping. The soft magnetic composite material shows the features: resistivity is controlled by insulating coating thickness and equals up to ρ =10-4 Ωṡm for metallic state and ρ =104 Ωṡm for insulator state, maximum magnetic permeability is μm = 2500 and μm = 300 respectively, induction is up to Bm=2.1 T. These properties of composite soft magnetic material allow applying for transformers, throttles, stator-rotor of high-efficient and powerful electric machines in 10 kHz-1MGz frequency range. For microsystems and microcomponents application, good opportunity to improve their reliability is the use of nanocomposite materials. Electroplating technology of nanocomposite magnetic materials into the ultra-thick micromolds will be presented. Co-deposition of the soft magnetic alloys with inert hard nanoparticles allows obtaining materials with magnetic permeability up to μm=104, magnetic induction of Bs=(0.62-1.3) T. Such LIGA-like technology will be applied in MEMS to produce high reliable devices with advanced physical properties.

Superconductor magnetic reading and writing heads

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barnes, F.S.; Dugas, M.P.

1990-11-20

This paper describes a head for interfacing with a magnetic recording media. It comprises: a member of magnetic material forming at least a portion of a magnetic flux circuit ending with a pole face surface in interfacing relation to the media for establishing a main pole in proximity to the media in the magnetic flux circuit, magnetically responsive means in magnetically coupled relation to the magnetic flux circuit, means encasing at least a portion of the external surfaces of the member with superconductive material except for the media interfacing portion of the pole face surface. The encasing means including superconductingmore » material substantially surrounding the magnetic flux circuit in proximity to the pole face surface, and means establishing an environment for the superconductive material at a temperature for maintaining the superconductive material in its superconductive state, whereby magnetic flux in the magnetic flux circuit associated with the encasing means is concentrated within the magnetic flux circuit while placement of the pole face surface in proximity to the recording media permits sensitive magnetic flux controlled information exchanges between the media and the head.« less

Magnetic Phase Diagram of α-RuCl3

NASA Astrophysics Data System (ADS)

Sears, Jennifer; Kim, Young-June; Zhao, Yang; Lynn, Jeffrey

The layered honeycomb material α-RuCl3 is thought to possess unusual magnetic interactions including a strong bond-dependent Kitaev term, offering a potential opportunity to study a material near a well understood spin liquid phase. Although this material orders magnetically at low temperatures and is thus not a realization of a Kitaev spin liquid, it does show a broad continuum of magnetic excitations reminiscent of that expected for the spin liquid phase. It has also been proposed that a magnetic field could destabilize the magnetic order in this material and induce a transition into a spin liquid phase. Low temperature magnetization and specific heat measurements in this material have suggested a complex magnetic phase diagram with multiple unidentified magnetic phases present at low temperature. This has provided motivation for our work characterizing the magnetic transitions and phase diagram in α-RuCl3. I will present detailed bulk measurements combined with magnetic neutron diffraction measurements to map out the phase diagram and identify the various phases present.

Research progress in photolectric materials of CuFeS2

NASA Astrophysics Data System (ADS)

Jing, Mingxing; Li, Jing; Liu, Kegao

2018-03-01

CuFeS2 as a photoelectric material, there are many advantages, such as high optical absorption coefficient, direct gap semiconductor, thermal stability, no photo-recession effect and so on. Because of its low price, abundant reserves and non-toxic, CuFeS2 has attracted extensive attention of scientists.Preparation method of thin film solar cells are included that Electrodeposition, sputtering, thermal evaporation, thermal spraying method, co-reduction method.In this paper, the development of CuFeS2 thin films prepared by co-reduction method and co-reduction method is introduced.In this paper, the structure and development of solar cells, advantages of CuFeS2 as solar cell material, the structure and photoelectric properties and magnetic properties of CuFeS2, preparation process analysis of CuFeS2 thin film, research and development of CuFeS2 in solar cells is included herein. Finally, the development trend of CuFeS2 optoelectronic materials is analyzed and further research directions are proposed.

Multiferroic RMnO3 thin films

NASA Astrophysics Data System (ADS)

Fontcuberta, Josep

2015-03-01

Multiferroic materials have received an astonishing attention in the last decades due to expectations that potential coupling between distinct ferroic orders could inspire new applications and new device concepts. As a result, a new knowledge on coupling mechanisms and materials science has dramatically emerged. Multiferroic RMnO3 perovskites are central to this progress, providing a suitable platform to tailor spin-spin and spin-lattice interactions. With views towards applications, the development of thin films of multiferroic materials have also progressed enormously and nowadays thin-film manganites are available, with properties mimicking those of bulk compounds. Here we review achievements on the growth of hexagonal and orthorhombic RMnO3 epitaxial thin films and the characterization of their magnetic and ferroelectric properties, we discuss some challenging issues, and we suggest some guidelines for future research and developments. En ce qui concerne les applications, le développement de films minces de matériaux multiferroïques a aussi énormément progressé, et de nos jours des films minces de manganites avec des propriétés similaires à celles des matériaux massifs existent. Nous passons en revue ici les résultats obtenus dans le domaine de la croissance de couches minces épitaxiés de RMnO3 hexagonal et orthorhombique et de la caractérisation de leurs propriétés magnétiques et ferroélectriques. Nous discutons certains enjeux et proposons quelques idées pour des recherches et développements futurs.

Magnetically attached sputter targets

DOEpatents

Makowiecki, D.M.; McKernan, M.A.

1994-02-15

An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material is described. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly. 11 figures.

Magnetically attached sputter targets

DOEpatents

Makowiecki, Daniel M.; McKernan, Mark A.

1994-01-01

An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly.

Method And Apparatus For Launching Microwave Energy Into A Plasma Processing Chamber

DOEpatents

DOUGHTY, FRANK C.; [et al

2001-05-01

A method and apparatus for launching microwave energy to a plasma processing chamber in which the required magnetic field is generated by a permanent magnet structure and the permanent magnet material effectively comprises one or more surfaces of the waveguide structure. The waveguide structure functions as an impedance matching device and controls the field pattern of the launched microwave field to create a uniform plasma. The waveguide launcher may comprise a rectangular waveguide, a circular waveguide, or a coaxial waveguide with permanent magnet material forming the sidewalls of the guide and a magnetization pattern which produces the required microwave electron cyclotron resonance magnetic field, a uniform field absorption pattern, and a rapid decay of the fields away from the resonance zone. In addition, the incorporation of permanent magnet material as a portion of the waveguide structure places the magnetic material in close proximity to the vacuum chamber, allowing for a precisely controlled magnetic field configuration, and a reduction of the amount of permanent magnet material required.

Controlling interactions between highly magnetic atoms with Feshbach resonances.

PubMed

Kotochigova, Svetlana

2014-09-01

This paper reviews current experimental and theoretical progress in the study of dipolar quantum gases of ground and meta-stable atoms with a large magnetic moment. We emphasize the anisotropic nature of Feshbach resonances due to coupling to fast-rotating resonant molecular states in ultracold s-wave collisions between magnetic atoms in external magnetic fields. The dramatic differences in the distribution of resonances of magnetic (7)S3 chromium and magnetic lanthanide atoms with a submerged 4f shell and non-zero electron angular momentum is analyzed. We focus on dysprosium and erbium as important experimental advances have been recently made to cool and create quantum-degenerate gases for these atoms. Finally, we describe progress in locating resonances in collisions of meta-stable magnetic atoms in electronic P-states with ground-state atoms, where an interplay between collisional anisotropies and spin-orbit coupling exists.

Magnetic bearings: Fifty years of progress

NASA Technical Reports Server (NTRS)

Swann, Michael K.

1993-01-01

Magnetic bearings are just beginning to be flown in spacecraft systems, but their development spans more than 50 years. The promise of completely noncontacting, unlubricated rotating systems operating at speeds substantially beyond the range of conventional bearings, and with no wear and virtually no vibration, has provided the incentive to develop magnetic bearing technology for many diverse applications. Earnshaw theorized in 1842 that stable magnetic suspension is not possible in all three spatial directions unless the magnetic field is actively controlled. Since that time, researchers have attempted to successfully support spinning rotors in a stable manner. Development of magnetic suspension systems over the past fifty years has included progress on both passive (permanent magnet) and active (electromagnet) systems. The improvements in bearing load capacity, stiffness, and damping characteristics are traced. The trends in rotor size, rotational kinetic energy, and improvements in active control systems capabilities are also reviewed. Implications of superconductivity on suspension system design and performance are discussed.

Nanocomposites Derived from Polymers and Inorganic Nanoparticles

PubMed Central

Jeon, In-Yup; Baek, Jong-Beom

2010-01-01

Polymers are considered to be good hosting matrices for composite materials because they can easily be tailored to yield a variety of bulk physical properties. Moreover, organic polymers generally have long-term stability and good processability. Inorganic nanoparticles possess outstanding optical, catalytic, electronic and magnetic properties, which are significantly different their bulk states. By combining the attractive functionalities of both components, nanocomposites derived from organic polymers and inorganic nanoparticles are expected to display synergistically improved properties. The potential applications of the resultant nanocomposites are various, e.g. automotive, aerospace, opto-electronics, etc. Here, we review recent progress in polymer-based inorganic nanoparticle composites.

Nonreciprocal frequency conversion in a multimode microwave optomechanical circuit

NASA Astrophysics Data System (ADS)

Feofanov, A. K.; Bernier, N. R.; Toth, L. D.; Koottandavida, A.; Kippenberg, T. J.

Nonreciprocal devices such as isolators, circulators, and directional amplifiers are pivotal to quantum signal processing with superconducting circuits. In the microwave domain, commercially available nonreciprocal devices are based on ferrite materials. They are barely compatible with superconducting quantum circuits, lossy, and cannot be integrated on chip. Significant potential exists for implementing non-magnetic chip-scale nonreciprocal devices using microwave optomechanical circuits. Here we demonstrate a possibility of nonreciprocal frequency conversion in a multimode microwave optomechanical circuit using solely optomechanical interaction between modes. The conversion scheme and the results reflecting the actual progress on the experimental implementation of the scheme will be presented.

A new type of magnetism-controllable Mn-based single-molecule magnet

NASA Astrophysics Data System (ADS)

Cui, Yan; Zhu, Huiping; Wang, Lei; Li, Bo; Han, Zhengsheng; Luo, Jiajun

2018-07-01

The flexibility and diversity of organic chemistry have yielded many materials in which magnetism can be varied. However, most methods used for changing magnetism are inefficient or destructive to the magnetic material. Here we report high-performance magnetic control of a gas-responsive single-molecule magnet (SMM). The results exhibit that the magnetic properties of the SMM can be significantly changed according to the gas environment it is in and some of the magnetic states can be reversibly transformed or coexistent in the SMM through artificial control. More importantly, the single crystalline structure of the SMM is almost the same during the transformation process except for slight change of the lattice constant. Thus, this work opens up new insights into the stimuli-responsive magnetic materials which have great prospects for application in artificial design magnetic network and also highlight their potential as smart materials.

Characteristics of anthropogenic magnetic materials in roadside dusts in Seoul, Korea using thermo-magnetic behaviors and electron microscope observations

NASA Astrophysics Data System (ADS)

Kim, W.; Doh, S.; Park, Y.

2006-12-01

It has been previously reported that magnetic concentration parameter (e.g., magnetic susceptibility) has a close affinity with heavy metal concentration in roadside dust of the Seoul metropolitan area. Magnetic concentration and magnetic particle size show systematic seasonal fluctuations (high and large during winter; low and small in summer) because of seasonal influx variation of anthropogenic magnetic materials. These observations suggest that magnetic parameters could be utilized as a proxy method of assessing heavy metal pollution in urban areas. In order to characterize anthropogenic magnetic materials and to find their potential sources, magnetic extracts from roadside dusts of Seoul metropolitan area were subject to SEM observation, elemental analysis (EDS), and thermo-magnetic experiments. Magnetic materials from vehicle emission and abraded brake lining were also observed for the comparison. The magnetic particles can be classified based on the morphology and elemental composition of the particles. Magnetic spherules are the most frequently observed type of particle throughout the study area. These particles are often associated with the elemental C and Al-Ca-Na-Si materials, and are believed to be the product of fossil fuel combustions in power plants, industries, and domestic heating systems. Aggregates of iron-oxides and Fe-C-S materials are probably originated from vehicle emission, while aggregates of pure Fe and Al-Ca-Fe-K-Mg-Si materials appear to be derived from abrasion of motor vehicle brake system. These aggregates are frequently observed in industrial sections of the city as well as areas of heavy traffic. Angular magnetic particles accompanied by silicates are only observed in park area and probably formed by natural process such as pedogenesis or weathering. Thermo-magnetic experiments indicate that the major magnetic phase in the studied samples is magnetite. Two distinctive behaviors observed are the presence of low Curie temperature magnetic phase and under- recover of susceptibility on cooling. It is considered that Fe-C-S magnetic aggregates possibly behaved like pyrrhotite, and thus recognized as low Curie temperature magnetic phase. A factor causing under-recover of susceptibility is attributed to some of magnetic spherules associated with C and Al-Ca-Na-Si materials which possibly behaved like iron-oxide containing impurities. Overall, this study shows that the magnetic methods in conjunction with SEM observations and elemental analyses for urban roadside dust can be used as a powerful tool for assessment of pollution features in an urban area in terms of source and spatial distribution of anthropogenic magnetic materials and associated heavy metals.

Rechargeable lithium-ion cell state of charge and defect detection by in-situ inside-out magnetic resonance imaging.

PubMed

Ilott, Andrew J; Mohammadi, Mohaddese; Schauerman, Christopher M; Ganter, Matthew J; Jerschow, Alexej

2018-05-03

When and why does a rechargeable battery lose capacity or go bad? This is a question that is surprisingly difficult to answer; yet, it lies at the heart of progress in the fields of consumer electronics, electric vehicles, and electrical storage. The difficulty is related to the limited amount of information one can obtain from a cell without taking it apart and analyzing it destructively. Here, we demonstrate that the measurement of tiny induced magnetic field changes within a cell can be used to assess the level of lithium incorporation into the electrode materials, and diagnose certain cell flaws that could arise from assembly. The measurements are fast, can be performed on finished and unfinished cells, and most importantly, can be done nondestructively with cells that are compatible with commercial design requirements with conductive enclosures.

Stabilized Liner Compressor: The Return of Linus

NASA Astrophysics Data System (ADS)

Turchi, Peter; Frese, Sherry; Frese, Michael; Mielke, Charles; Hinrichs, Mark; Nguyen, Doan

2015-11-01

To access the lower cost regime of magneto-inertial fusion at megagauss magnetic field-levels requires the use of dynamic conductors in the form of imploding cylindrical shells, aka, liners. Such liner implosions can compress magnetic flux and plasma to attain fusion conditions, but are subject to Rayleigh-Taylor instabilities, both in the launch and recovery of the liner material and in the final few diameters of implosion. These instabilities were overcome in the Linus program at the Naval Research Laboratory, c. 1979, providing the experimentally-demonstrated basis for repetitive operation and leading to an economical reactor concept at low fusion gain. The recent ARPA-E program for low-cost fusion technology has revived interest in this approach. We shall discuss progress in modeling and design of a Stabilized Liner Compressor (SLC) that extends the earlier work to higher pressures and liner speeds appropriate to potential plasma targets. Sponsored by ARPA-E ALPHA Program.

Astrophysically Relevant Dipole Studies at WiPAL

NASA Astrophysics Data System (ADS)

Endrizzi, Douglass; Forest, Cary; Wallace, John; WiPAL Team

2015-11-01

A novel terrella experiment is being developed to immerse a dipole magnetic field in the large, unmagnetized, and fully ionized background plasma of WiPAL (Wisconsin Plasma Astrophysics Lab). This allows for a series of related experiments motivated by astrophysical processes, including (1) inward transport of plasma into a magnetosphere with focus on development of Kelvin-Helmholtz instabilities from boundary shear flow; (2) helicity injection and simulation of solar eruptive events via electrical breakdown along dipole field lines; (3) interaction of Coronal Mass Ejection-like flows with a target magnetosphere and dependence on background plasma pressure; (4) production of a centrifugally driven wind to study how dipolar magnetic topology changes as closed field lines open. A prototype has been developed and preliminary results will be presented. An overview of the final design and construction progress will be given. This material is based upon work supported by the NSF Graduate Research Fellowship Program.

Review of progress in magnetic particle inspection

NASA Astrophysics Data System (ADS)

Eisenmann, David J.; Enyart, Darrel; Lo, Chester; Brasche, Lisa

2014-02-01

Magnetic particle inspection (MPI) has been widely utilized for decades, and sees considerable use in the aerospace industry with a majority of the steel parts being inspected with MPI at some point in the lifecycle. Typical aircraft locations inspected are landing gear, engine components, attachment hardware, and doors. In spite of its numerous applications the method remains poorly understood, and there are many aspects of that method which would benefit from in-depth study. This shortcoming is due to the fact that MPI combines the complicated nature of electromagnetics, metallurgical material effects, fluid-particle motion dynamics, and physiological human factors into a single inspection. To promote understanding of the intricate method issues that affect sensitivity, or to assist with the revision of industry specifications and standards, research studies will be prioritized through the guidance of a panel of industry experts, using an approach which has worked successfully in the past to guide fluorescent penetrant inspection (FPI) research efforts.

Overview of the present progress and activities on the CFETR

NASA Astrophysics Data System (ADS)

Wan, Yuanxi; Li, Jiangang; Liu, Yong; Wang, Xiaolin; Chan, Vincent; Chen, Changan; Duan, Xuru; Fu, Peng; Gao, Xiang; Feng, Kaiming; Liu, Songlin; Song, Yuntao; Weng, Peide; Wan, Baonian; Wan, Farong; Wang, Heyi; Wu, Songtao; Ye, Minyou; Yang, Qingwei; Zheng, Guoyao; Zhuang, Ge; Li, Qiang; CFETR Team

2017-10-01

The China Fusion Engineering Test Reactor (CFETR) is the next device in the roadmap for the realization of fusion energy in China, which aims to bridge the gaps between the fusion experimental reactor ITER and the demonstration reactor (DEMO). CFETR will be operated in two phases. Steady-state operation and self-sufficiency will be the two key issues for Phase I with a modest fusion power of up to 200 MW. Phase II aims for DEMO validation with a fusion power over 1 GW. Advanced H-mode physics, high magnetic fields up to 7 T, high frequency electron cyclotron resonance heating and lower hybrid current drive together with off-axis negative-ion neutral beam injection will be developed for achieving steady-state advanced operation. The recent detailed design, research and development (R&D) activities including integrated modeling of operation scenarios, high field magnet, material, tritium plant, remote handling and future plans are introduced in this paper.

The magnetization process: Hysteresis

NASA Technical Reports Server (NTRS)

Balsamel, Richard

1990-01-01

The magnetization process, hysteresis (the difference in the path of magnetization for an increasing and decreasing magnetic field), hysteresis loops, and hard magnetic materials are discussed. The fabrication of classroom projects for demonstrating hysteresis and the hysteresis of common magnetic materials is described in detail.

Recent progress in magnetic iron oxide-semiconductor composite nanomaterials as promising photocatalysts

NASA Astrophysics Data System (ADS)

Wu, Wei; Changzhong Jiang, Affc; Roy, Vellaisamy A. L.

2014-11-01

Photocatalytic degradation of toxic organic pollutants is a challenging tasks in ecological and environmental protection. Recent research shows that the magnetic iron oxide-semiconductor composite photocatalytic system can effectively break through the bottleneck of single-component semiconductor oxides with low activity under visible light and the challenging recycling of the photocatalyst from the final products. With high reactivity in visible light, magnetic iron oxide-semiconductors can be exploited as an important magnetic recovery photocatalyst (MRP) with a bright future. On this regard, various composite structures, the charge-transfer mechanism and outstanding properties of magnetic iron oxide-semiconductor composite nanomaterials are sketched. The latest synthesis methods and recent progress in the photocatalytic applications of magnetic iron oxide-semiconductor composite nanomaterials are reviewed. The problems and challenges still need to be resolved and development strategies are discussed.

Magnetic Characterization of Organic Materials

DTIC Science & Technology

2016-12-12

measurements. Magnetic shielding of nearby optical components was achieved for reliable experimental results. Magnetic -field applied ultrafast broadband...AFRL-AFOSR-JP-TR-2017-0005 Magnetic Characterization of Organic Materials Dongho Kim YONSEI UNIVERSITY UNIVERSITY-INDUSTRY FOUNDATION Final Report 12...Final 3. DATES COVERED (From - To) 10 Sep 2015 to 09 Sep 2016 4. TITLE AND SUBTITLE Magnetic Characterization of Organic Materials 5a.  CONTRACT

High Temperature Texturing of Engineered Materials in a Magnetic Field

DTIC Science & Technology

2003-03-01

by 43.7 % after magnetic annealing in a 19 T field. The kink at the demagnetization curve disappeared and, in addition, a much better squareness of...the demagnetization curves was observed after the magnetic annealing (Figure 10). The improvement in the hard magnetic properties after magnetic ...A number of materials systems have been tested in a variety of magnetic fields (8-20 Tesla) and temperatures (500 to 1250oC). Four materials

Rational design of new materials for spintronics: Co2FeZ (Z=Al, Ga, Si, Ge)

PubMed Central

Balke, Benjamin; Wurmehl, Sabine; Fecher, Gerhard H; Felser, Claudia; Kübler, Jürgen

2008-01-01

Spintronic is a multidisciplinary field and a new research area. New materials must be found for satisfying the different types of demands. The search for stable half-metallic ferromagnets and ferromagnetic semiconductors with Curie temperatures higher than room temperature is still a challenge for solid state scientists. A general understanding of how structures are related to properties is a necessary prerequisite for material design. Computational simulations are an important tool for a rational design of new materials. The new developments in this new field are reported from the point of view of material scientists. The development of magnetic Heusler compounds specifically designed as material for spintronic applications has made tremendous progress in the very recent past. Heusler compounds can be made as half-metals, showing a high spin polarization of the conduction electrons of up to 100% in magnetic tunnel junctions. High Curie temperatures were found in Co2-based Heusler compounds with values up to 1120 K in Co2FeSi. The latest results at the time of writing are a tunnelling magnet resistance (TMR) device made from the Co2FeAl0.5Si0.5 Heusler compound and working at room temperature with a (TMR) effect higher than 200%. Good interfaces and a well-ordered compound are the precondition to realize the predicted half-metallic properties. The series Co2FeAl1- xSix is found to exhibit half-metallic ferromagnetism over a broad range, and it is shown that electron doping stabilizes the gap in the minority states for x=0.5. This might be a reason for the exceptional temperature behaviour of Co2FeAl0.5Si0.5 TMR devices. Using x-ray diffraction (XRD), it was shown conclusively that Co2FeAl crystallizes in the B2 structure whereas Co2FeSi crystallizes in the L21 structure. For the compounds Co2FeGa or Co2FeGe, with Curie temperatures expected higher than 1000 K, the standard XRD technique using laboratory sources cannot be used to easily distinguish between the two structures. For this reason, the EXAFS technique was used to elucidate the structure of these two compounds. Analysis of the data indicated that both compounds crystallize in the L21 structure which makes these two compounds suitable new candidates as materials in magnetic tunnel junctions. PMID:27877928

Magnetic graphene oxide modified by imidazole-based ionic liquids for the magnetic-based solid-phase extraction of polysaccharides from brown alga.

PubMed

Wang, Xiaoqin; Li, Guizhen; Row, Kyung Ho

2017-08-01

Magnetic graphene oxide was modified by four imidazole-based ionic liquids to synthesize materials for the extraction of polysaccharides by magnetic solid-phase extraction. Fucoidan and laminarin were chosen as the representative polysaccharides owing to their excellent pharmaceutical value and availability. Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, and thermogravimetric analysis were applied to characterize the synthesized materials. Single-factor experiments showed that the extraction efficiency of polysaccharides was affected by the amount of ionic liquids for modification, solid-liquid ratio of brown alga and ethanol, the stirring time of brown alga and ionic liquid-modified magnetic graphene oxide materials, and amount of 1-(3-aminopropyl)imidazole chloride modified magnetic graphene oxide materials added to the brown alga sample solution. The results indicated that 1-(3-aminopropyl)imidazole chloride modified magnetic graphene oxide possessed better extraction ability than graphene oxide, magnetic graphene oxide, and other three ionic-liquid-modified magnetic graphene oxide materials. The highest extraction recoveries of fucoidan and laminarin extracted by 1-(3-aminopropyl)imidazole chloride modified magnetic graphene oxide were 93.3 and 87.2%, respectively. In addition, solid materials could be separated and reused easily owing to their magnetic properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel no-insulation winding technique of high temperature-superconducting racetrack coil for rotating applications: A progress report in Korea university.

PubMed

Choi, Y H; Song, J B; Yang, D G; Kim, Y G; Hahn, S; Lee, H G

2016-10-01

This paper presents our recent progress on core technology development for a megawatt-class superconducting wind turbine generator supported by the international collaborative R&D program of the Korea Institute of Energy Technology Evaluation and Planning. To outperform the current high-temperature-superconducting (HTS) magnet technology in the wind turbine industry, a novel no-insulation winding technique was first proposed to develop the second-generation HTS racetrack coil for rotating applications. Here, we briefly report our recent studies on no-insulation (NI) winding technique for GdBCO coated conductor racetrack coils in the following areas: (1) Charging-discharging characteristics of no-insulation GdBCO racetrack coils with respect to external pressures applied to straight sections; (2) thermal and electrical stabilities of no-insulation GdBCO racetrack coils encapsulated with various impregnating materials; (3) quench behaviors of no-insulation racetrack coils wound with GdBCO conductor possessing various lamination layers; (4) electromagnetic characteristics of no-insulation GdBCO racetrack coils under time-varying field conditions. Test results confirmed that this novel NI winding technique was highly promising. It could provide development of a compact, mechanically dense, and self-protecting GdBCO magnet for use in real-world superconducting wind turbine generators.

A novel no-insulation winding technique of high temperature-superconducting racetrack coil for rotating applications: A progress report in Korea university

NASA Astrophysics Data System (ADS)

Choi, Y. H.; Song, J. B.; Yang, D. G.; Kim, Y. G.; Hahn, S.; Lee, H. G.

2016-10-01

This paper presents our recent progress on core technology development for a megawatt-class superconducting wind turbine generator supported by the international collaborative R&D program of the Korea Institute of Energy Technology Evaluation and Planning. To outperform the current high-temperature-superconducting (HTS) magnet technology in the wind turbine industry, a novel no-insulation winding technique was first proposed to develop the second-generation HTS racetrack coil for rotating applications. Here, we briefly report our recent studies on no-insulation (NI) winding technique for GdBCO coated conductor racetrack coils in the following areas: (1) Charging-discharging characteristics of no-insulation GdBCO racetrack coils with respect to external pressures applied to straight sections; (2) thermal and electrical stabilities of no-insulation GdBCO racetrack coils encapsulated with various impregnating materials; (3) quench behaviors of no-insulation racetrack coils wound with GdBCO conductor possessing various lamination layers; (4) electromagnetic characteristics of no-insulation GdBCO racetrack coils under time-varying field conditions. Test results confirmed that this novel NI winding technique was highly promising. It could provide development of a compact, mechanically dense, and self-protecting GdBCO magnet for use in real-world superconducting wind turbine generators.

Magnetic and Electrical Characteristics of Cobalt-Based Amorphous Materials and Comparison to a Permalloy Type Polycrystalline Material

NASA Technical Reports Server (NTRS)

Wieserman, William R.; Schwarze, Gene E.; Niedra, Janis M.

2005-01-01

Magnetic component designers are always looking for improved soft magnetic core materials to increase the efficiency, temperature rating and power density of transformers, motors, generators and alternators, and energy density of inductors. In this paper, we report on the experimental investigation of commercially available cobalt-based amorphous alloys which, in their processing, were subjected to two different types of magnetic field anneals: A longitudinal magnetic field anneal or a transverse magnetic field anneal. The longitudinal field annealed material investigated was Metglas 2714A. The electrical and magnetic characteristics of this material were investigated over the frequency range of 1 to 200 kHz and temperature range of 23 to 150 C for both sine and square wave voltage excitation. The specific core loss was lower for the square than the sine wave voltage excitation for the same maximum flux density, frequency and temperature. The transverse magnetic field annealed core materials include Metglas 2714AF and Vacuumschmelze 6025F. These two materials were experimentally characterized over the frequency range of 10 to 200 kHz for sine wave voltage excitation and 23 C only. A comparison of the 2174A to 2714AF found that 2714AF always had lower specific core loss than 2714A for any given magnetic flux density and frequency and the ratio of specific core loss of 2714A to 2714AF was dependent on both magnetic flux density and frequency. A comparison was also made of the 2714A, 2714AF, and 6025F materials to two different tape thicknesses of the polycrystalline Supermalloy material and the results show that 2714AF and 6025F have the lowest specific core loss at 100 kHz over the magnetic flux density range of 0.1 to 0.4 Tesla.

Randomized Double-Blind Placebo-Controlled Trial of Bevacizumab Therapy for Radiation Necrosis of the Central Nervous System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levin, Victor A., E-mail: vlevin49@comcast.ne; Bidaut, Luc; Hou, Ping

Purpose: To conduct a controlled trial of bevacizumab for the treatment of symptomatic radiation necrosis of the brain. Methods and Materials: A total of 14 patients were entered into a placebo-controlled randomized double-blind study of bevacizumab for the treatment of central nervous system radiation necrosis. All patients were required to have radiographic or biopsy proof of central nervous system radiation necrosis and progressive neurologic symptoms or signs. Eligible patients had undergone irradiation for head-and-neck carcinoma, meningioma, or low- to mid-grade glioma. Patients were randomized to receive intravenous saline or bevacizumab at 3-week intervals. The magnetic resonance imaging findings 3 weeksmore » after the second treatment and clinical signs and symptoms defined the response or progression. Results: The volumes of necrosis estimated on T{sub 2}-weighted fluid-attenuated inversion recovery and T{sub 1}-weighted gadolinium-enhanced magnetic resonance imaging scans demonstrated that although no patient receiving placebo responded (0 of 7), all bevacizumab-treated patients did so (5 of 5 randomized and 7 of 7 crossover) with decreases in T{sub 2}-weighted fluid-attenuated inversion recovery and T{sub 1}-weighted gadolinium-enhanced volumes and a decrease in endothelial transfer constant. All bevacizumab-treated patients-and none of the placebo-treated patients-showed improvement in neurologic symptoms or signs. At a median of 10 months after the last dose of bevacizumab in patients receiving all four study doses, only 2 patients had experienced a recurrence of magnetic resonance imaging changes consistent with progressive radiation necrosis; one patient received a single additional dose of bevacizumab and the other patient received two doses. Conclusion: The Class I evidence of bevacizumab efficacy from the present study in the treatment of central nervous system radiation necrosis justifies consideration of this treatment option for people with radiation necrosis secondary to the treatment of head-and-neck cancer and brain cancer.« less

Silica based hybrid materials for drug delivery and bioimaging.

PubMed

Bagheri, Elnaz; Ansari, Legha; Abnous, Khalil; Taghdisi, Seyed Mohammad; Charbgoo, Fahimeh; Ramezani, Mohammad; Alibolandi, Mona

2018-05-10

Silica hybrid materials play an important role in improvement of novel progressive functional nanomaterials. Study in silica hybrid functional materials is supported by growing interest in providing intelligent materials that combine best of the inorganic silica structure along with organic or biological realms. Hybrid silica materials do not only provide fantastic opportunities for the design of novel materials for research but their represented unique properties open versatile applications specifically in nanomedicine since it was recognized by US FDA as a safe material for human trials. By combining various materials with different characteristics along with silica NPs as building blocks, silica-based hybrid vehicles were developed. In this regard, silica-based hybrid materials have shown great capabilities as unique carriers for bioimaging and/or drug delivery purposes. In the aforementioned hybrid systems, silica was preferred as a main building block of the hybrid structure, which is easily functionalized with different materials, bio-molecules and targeting ligands while providing biocompatibility for the system. This review will cover a full description of different hybrids of silica nanoparticles including silica-polymer, silica-protein, silica-peptide, silica-nucleic acid, silica-gold, silica-quantum dot, and silica-magnetic nanoparticles and their applications as therapeutic or imaging systems. Copyright © 2018 Elsevier B.V. All rights reserved.

Experimental realization of dynamo action: present status and prospects

NASA Astrophysics Data System (ADS)

Giesecke, André; Stefani, Frank; Gundrum, Thomas; Gerbeth, Gunter; Nore, Caroline; Léorat, Jacques

2013-07-01

In the last decades, the experimental study of dynamo action has made great progress. However, after the dynamo experiments in Karlsruhe and Riga, the von-Kármán-Sodium (VKS) dynamo is only the third facility that has been able to demonstrate fluid flow driven self-generation of magnetic fields in a laboratory experiment. Further progress in the experimental examination of dynamo action is expected from the planned precession driven dynamo experiment that will be designed in the framework of the liquid sodium facility DRESDYN (DREsden Sodium facility for DYNamo and thermohydraulic studies). In this paper, we briefly present numerical models of the VKS dynamo that demonstrate the close relation between the axisymmetric field observed in that experiment and the soft iron material used for the flow driving impellers. We further show recent results of preparatory water experiments and design studies related to the precession dynamo and delineate the scientific prospects for the final set-up.

Component technology for space power systems

NASA Technical Reports Server (NTRS)

Finke, R.

1982-01-01

The Lewis/OAST program for the development of Component Technology for Space Power Systems is described. The program is divided into five generic areas: semiconductor devices (transistors, thyristors, and diodes); conductors (materials and transmission lines); dielectrics; magnetic devices; and thermal control devices. Examples of progress in each of the five areas is discussed. Bipolar power transistors up to 1000 V at 100 A with a gain of 10 and a 0.5 mu sec rise and fall time are presented. A new class of semiconductor devices with a possibility of switching 1000 000 V is described. Several 100 kW rotary power transformer designs and a 25 kW, 20 kHz transformer weighting 3.2 kg have been developed. Progress on the creation of diamond-like films for thermal devices and intercalated carbon fibers with the strength of steel and the conductivity of copper at one third the mass of copper is presented.

EDITORIAL: Progress in applications of magnetic nanoparticles in biomedicine Progress in applications of magnetic nanoparticles in biomedicine

NASA Astrophysics Data System (ADS)

O'Grady, Kevin

2009-11-01

In 2003 Journal of Physics D: Applied Physics published three sequential review articles on the subject of biomedical applications of magnetic nanoparticles. At that time there was growing interest in basic research on the potential of magnetic nanoparticles in biomedicine, including the appropriate methods to synthesize the particles and how to functionalize them. Following that initial publication the field has burgeoned and is now of a scale that could never have been envisaged in 2003. In the original review articles the authors anticipated applications in three specific technical areas of drug delivery and cell separation, MRI contrast enhancement and hyperthermic heating of biological materials, either for cell destruction or to increase the efficacy of other associated treatments such as chemotherapy. Six years later, significant progress has been made in all three areas, with applications already having been realized. More significantly, in vivo applications of both MRI contrast and hyperthermic cell heating have been achieved in human patients. This rapid progress in such a complex field is due to the need for non-invasive therapies and more effective management of serious conditions than is possible by the simple use of drugs alone. Imaging techniques such as MRI have also improved beyond all expectation and hence the possibility of improved contrast is particularly appealing. However, none of these applications could have been realized without dramatic progress beyond the state of the art in 2003 in the areas of particle synthesis and functionalization. Hence, remarkable progress has been made in all areas of the physics, chemistry and biochemistry of this subject, leading to many publications and perhaps a ten-fold increase in the number of those actively involved in research in this area. In 2003 we were most fortunate to have several expert authors review the subject. Quentin Pankhurst, Puerto Morales and Catherine Berry are now recognized as leaders within their own areas of the field. Because that field is moving rapidly and has now become a major subject of study, we believe that a collection of updated reviews would be highly appropriate and beneficial to the community. We have been fortunate in getting the same authors to provide six-year updates of their original works. This offers continuity and also allows those who may be new to this area to refer back to the original reviews for a full description of the basic science. In the interests of economy and to avoid repetition, this new set of reviews should be read in conjunction with the original works. The Editorial Board of J. Phys D is particularly grateful to the authors for agreeing to write a second work for our journal. We are aware that the production of reviews is an onerous task and acknowledge their efforts in making available such clear and high quality papers. We trust these new works will prove as beneficial to readers and as successful for their authors as were their original reviews.

R&D Progress of HTS Magnet Project for Ultrahigh-field MRI

NASA Astrophysics Data System (ADS)

Tosaka, Taizo; Miyazaki, Hiroshi; Iwai, Sadanori; Otani, Yasumi; Takahashi, Masahiko; Tasaki, Kenji; Nomura, Shunji; Kurusu, Tsutomu; Ueda, Hiroshi; Noguchi, So; Ishiyama, Atsushi; Urayama, Shinichi; Fukuyama, Hidenao

An R&D project on high-temperature superconducting (HTS) magnets using rare-earth Ba2Cu3O7 (REBCO) wires was started in 2013. The project objective is to investigate the feasibility of adapting REBCO magnets to ultrahigh field (UHF) magnetic resonance imaging (MRI) systems. REBCO wires are promising components for UHF-MRI magnets because of their superior superconducting and mechanical properties, which make them smaller and lighter than conventional ones. Moreover, REBCO magnets can be cooled by the conduction-cooling method, making liquid helium unnecessary. In the past two years, some test coils and model magnets have been fabricated and tested. This year is the final year of the project. The goals of the project are: (1) to generate a 9.4 T magnetic field with a small test coil, (2) to generate a homogeneous magnetic field in a 200 mm diameter spherical volume with a 1.5 T model magnet, and (3) to perform imaging with the 1.5 T model magnet. In this paper, the progress of this R&D is described. The knowledge gained through these R&D results will be reflected in the design of 9.4 T MRI magnets for brain and whole body imaging.

Tailoring Magnetic Properties in Bulk Nanostructured Solids

NASA Astrophysics Data System (ADS)

Morales, Jason Rolando

Important magnetic properties and behaviors such as coercivity, remanence, susceptibility, energy product, and exchange coupling can be tailored by controlling the grain size, composition, and density of bulk magnetic materials. At nanometric length scales the grain size plays an increasingly important role since magnetic domain behavior and grain boundary concentration determine bulk magnetic behavior. This has spurred a significant amount of work devoted to developing magnetic materials with nanometric features (thickness, grain/crystallite size, inclusions or shells) in 0D (powder), 1D (wires), and 2D (thin films) materials. Large 3D nanocrystalline materials are more suitable for many applications such as permanent magnets, magneto-optical Faraday isolators etc. Yet there are relatively few successful demonstrations of 3D magnetic materials with nanoscale influenced properties available in the literature. Making dense 3D bulk materials with magnetic nanocrystalline microstructures is a challenge because many traditional densification techniques (HIP, pressureless sintering, etc.) move the microstructure out of the "nano" regime during densification. This dissertation shows that the Current Activated Pressure Assisted Densification (CAPAD) method, also known as spark plasma sintering, can be used to create dense, bulk, magnetic, nanocrystalline solids with varied compositions suited to fit many applications. The results of my research will first show important implications for the use of CAPAD for the production of exchange-coupled nanocomposite magnets. Decreases in grain size were shown to have a significant role in increasing the magnitude of exchange bias. Second, preferentially ordered bulk magnetic materials were produced with highly anisotropic material properties. The ordered microstructure resulted in changing magnetic property magnitudes (ex. change in coercivity by almost 10x) depending on the relative orientation (0° vs. 90°) of an externally applied magnetic field to the sample. Third, a dense magneto-optical material (rare earth oxide) was produced that rotates transmitted polarized light under an externally applied magnetic field, called the Faraday Effect. The magnitude of the rare earth oxide Faraday Effect surpasses that of the current market leader (terbium gallium garnet) in Faraday isolators by ˜2.24x.

Colloidal Magnetic Heterostructured Nanocrystals with Asymmetric Topologies: Seeded-Growth Synthetic Routes and Formation Mechanisms

NASA Astrophysics Data System (ADS)

Scarfiello, Riccardo; Nobile, Concetta; Cozzoli, P. Davide

2016-12-01

Colloidal inorganic nanocrystals, free-standing crystalline nanostructures generated and processed in solution phase, represent an important class of advanced nanoscale materials owing to the flexibility with which their physical-chemical properties can be controlled through synthetic tailoring of their compositional, structural and geometric features and the versatility with which they can be integrated in technological fields as diverse as optoelectronics, energy storage/ conversion/production, catalysis and biomedicine. In recent years, building upon mechanistic knowledge acquired on the thermodynamic and kinetic processes that underlie nanocrystal evolution in liquid media, synthetic nanochemistry research has made impressive advances, opening new possibilities for the design, creation and mastering of increasingly complex “colloidal molecules”, in which nanocrystal modules of different materials are clustered together via solid-state bonding interfaces into free-standing, easily processable multifunctional nanocomposite systems. This Review will provide a glimpse into this fast-growing research field by illustrating progress achieved in the wet-chemical development of last-generation breeds of all-inorganic heterostructured nanocrystals (HNCs) in asymmetric non-onionlike geometries, inorganic analogues of polyfunctional organic molecules, in which distinct nanoscale crystalline modules are interconnected in hetero-dimer, hetero-oligomer and anisotropic multidomain architectures via epitaxial heterointerfaces of limited extension. The focus will be on modular HNCs entailing at least one magnetic material component combined with semiconductors and/or metals, which hold potential for generating enhanced or unconventional magnetic properties, while offering diversified or even new chemical-physical properties and functional capabilities. The available toolkit of synthetic strategies, all based on the manipulation of seeded-growth techniques, will be described, revisited and critically interpreted within the framework of the currently understood mechanisms of colloidal heteroepitaxy.

Magnetic field sensor for isotropically sensing an incident magnetic field in a sensor plane

NASA Technical Reports Server (NTRS)

Pant, Bharat B. (Inventor); Wan, Hong (Inventor)

2001-01-01

A magnetic field sensor that isotropically senses an incident magnetic field. This is preferably accomplished by providing a magnetic field sensor device that has one or more circular shaped magnetoresistive sensor elements for sensing the incident magnetic field. The magnetoresistive material used is preferably isotropic, and may be a CMR material or some form of a GMR material. Because the sensor elements are circular in shape, shape anisotropy is eliminated. Thus, the resulting magnetic field sensor device provides an output that is relatively independent of the direction of the incident magnetic field in the sensor plane.

Recycled Sm-Co bonded magnet filaments for 3D printing of magnets

NASA Astrophysics Data System (ADS)

Khazdozian, Helena A.; Manzano, J. Sebastián; Gandha, Kinjal; Slowing, Igor I.; Nlebedim, Ikenna C.

2018-05-01

Recycling of rare earth elements, such as Sm and Nd, is one technique towards mitigating long-term supply and cost concerns for materials and devices that depend on these elements. In this work recycled Sm-Co powder recovered from industrial grinding swarfs, or waste material from magnet processing, was investigated for use in preparation of filament for 3D printing of bonded magnets. Recycled Sm-Co powder recovered from swarfs was blended into polylactic acid (PLA). Up to 20 vol.% of the recycled Sm-Co in PLA was extruded at 160°C to produce a filament. It was demonstrated that no degradation of magnetic properties occurred due to the preparation or extrusion of the bonded magnet material. Good uniformity of the magnetic properties is exhibited throughout the filament, with the material first extruded being the exception. The material does exhibit some magnetic anisotropy, allowing for the possibility of the development of anisotropic filaments. This work provides a path forward for producing recycled magnetic filament for 3D printing of permanent magnets.

Recycled Sm-Co bonded magnet filaments for 3D printing of magnets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khazdozian, Helena A.; Manzano, J. Sebastián; Gandha, Kinjal

Recycling of rare earth elements, such as Sm and Nd, is one technique towards mitigating long-term supply and cost concerns for materials and devices that depend on these elements. In this work recycled Sm-Co powder recovered from industrial grinding swarfs, or waste material from magnet processing, was investigated for use in preparation of filament for 3D printing of bonded magnets. Recycled Sm-Co powder recovered from swarfs was blended into polylactic acid (PLA). Up to 20 vol.% of the recycled Sm-Co in PLA was extruded at 160°C to produce a filament. It was demonstrated that no degradation of magnetic properties occurredmore » due to the preparation or extrusion of the bonded magnet material. Good uniformity of the magnetic properties is exhibited throughout the filament, with the material first extruded being the exception. The material does exhibit some magnetic anisotropy, allowing for the possibility of the development of anisotropic filaments. Finally, this work provides a path forward for producing recycled magnetic filament for 3D printing of permanent magnets.« less

Recycled Sm-Co bonded magnet filaments for 3D printing of magnets

DOE PAGES

Khazdozian, Helena A.; Manzano, J. Sebastián; Gandha, Kinjal; ...

2018-01-11

Recycling of rare earth elements, such as Sm and Nd, is one technique towards mitigating long-term supply and cost concerns for materials and devices that depend on these elements. In this work recycled Sm-Co powder recovered from industrial grinding swarfs, or waste material from magnet processing, was investigated for use in preparation of filament for 3D printing of bonded magnets. Recycled Sm-Co powder recovered from swarfs was blended into polylactic acid (PLA). Up to 20 vol.% of the recycled Sm-Co in PLA was extruded at 160°C to produce a filament. It was demonstrated that no degradation of magnetic properties occurredmore » due to the preparation or extrusion of the bonded magnet material. Good uniformity of the magnetic properties is exhibited throughout the filament, with the material first extruded being the exception. The material does exhibit some magnetic anisotropy, allowing for the possibility of the development of anisotropic filaments. Finally, this work provides a path forward for producing recycled magnetic filament for 3D printing of permanent magnets.« less

Noise reduction in heat-assisted magnetic recording of bit-patterned media by optimizing a high/low Tc bilayer structure

NASA Astrophysics Data System (ADS)

Muthsam, O.; Vogler, C.; Suess, D.

2017-12-01

It is assumed that heat-assisted magnetic recording is the recording technique of the future. For pure hard magnetic grains in high density media with an average diameter of 5 nm and a height of 10 nm, the switching probability is not sufficiently high for the use in bit-patterned media. Using a bilayer structure with 50% hard magnetic material with low Curie temperature and 50% soft magnetic material with high Curie temperature to obtain more than 99.2% switching probability leads to very large jitter. We propose an optimized material composition to reach a switching probability of Pswitch > 99.2% and simultaneously achieve the narrow transition jitter of pure hard magnetic material. Simulations with a continuous laser spot were performed with the atomistic simulation program VAMPIRE for a single cylindrical recording grain with a diameter of 5 nm and a height of 10 nm. Different configurations of soft magnetic material and different amounts of hard and soft magnetic material were tested and discussed. Within our analysis, a composition with 20% soft magnetic and 80% hard magnetic material reaches the best results with a switching probability Pswitch > 99.2%, an off-track jitter parameter σoff,80/20 = 0.46 nm and a down-track jitter parameter σdown,80/20 = 0.49 nm.

Digital lock-in detection of site-specific magnetism in magnetic materials

DOEpatents

Haskel, Daniel [Naperville, IL; Lang, Jonathan C [Naperville, IL; Srajer, George [Oak Park, IL

2008-07-22

The polarization and diffraction characteristics of x-rays incident upon a magnetic material are manipulated to provide a desired magnetic sensitivity in the material. The contrast in diffracted intensity of opposite helicities of circularly polarized x-rays is measured to permit separation of magnetic signals by element type and by atomic environment. This allows for the direct probing of magnetic signals from elements of the same species in nonequivalent atomic environments to better understand the behavior and characteristics of permanent magnetic materials. By using known crystallographic information together with manipulation of the polarization of x-rays having energies tuned near element-specific electronic excitations and by detecting and comparing the incident and diffracted photons at the same frequency, more accurate magnetic measurements can be made over shorter observation periods.

Development of magnesium diboride (MgB 2) wires and magnets using in situ strand fabrication method

NASA Astrophysics Data System (ADS)

Tomsic, Michael; Rindfleisch, Matthew; Yue, Jinji; McFadden, Kevin; Doll, David; Phillips, John; Sumption, Mike D.; Bhatia, Mohit; Bohnenstiehl, Scot; Collings, E. W.

2007-06-01

Since 2001 when magnesium diboride (MgB 2) was first reported to have a transition temperature of 39 K, conductor development has progressed to where MgB 2 superconductor wire in kilometer-long piece-lengths has been demonstrated in magnets and coils. Work has started on demonstrating MgB 2 wire in superconducting devices now that the wire is available commercially. MgB 2 superconductors and coils have the potential to be integrated in a variety of commercial applications such as magnetic resonance imaging, fault current limiters, transformers, motors, generators, adiabatic demagnetization refrigerators, magnetic separation, magnetic levitation, energy storage, and high energy physics applications. This paper discusses the progress on MgB 2 conductor and coil development in the last several years at Hyper Tech Research, Inc.

The Progress of Research Project for Magnetized Target Fusion in China

NASA Astrophysics Data System (ADS)

Yang, Xian-Jun

2015-11-01

The fusion of magnetized plasma called Magnetized Target Fusion (MTF) is a hot research area recently. It may significantly reduce the cost and size. Great progress has been achieved in past decades around the world. Five years ago, China initiated the MTF project and has gotten some progress as follows: 1. Verifying the feasibility of ignition of MTF by means of first principle and MHD simulation; 2. Generating the magnetic field over 1400 Tesla, which can be suppress the heat conduction from charged particles, deposit the energy of alpha particle to promote the ignition process, and produce the stable magnetized plasma for the target of ignition; 3. The imploding facility of FP-1 can put several Mega Joule energy to the solid liner of about ten gram in the range of microsecond risen time, while the simulating tool has been developed for design and analysis of the process; 4. The target of FRC can be generated by ``YG 1 facility'' while some simulating tools have be developed. Next five years, the above theoretical work and the experiments of MTF may be integrated to step up as the National project, which may make my term play an important lead role and be supposed to achieve farther progress in China. Supported by the National Natural Science Foundation of China under Grant No 11175028.

Electrical Machines Laminations Magnetic Properties: A Virtual Instrument Laboratory

ERIC Educational Resources Information Center

Martinez-Roman, Javier; Perez-Cruz, Juan; Pineda-Sanchez, Manuel; Puche-Panadero, Ruben; Roger-Folch, Jose; Riera-Guasp, Martin; Sapena-Baño, Angel

2015-01-01

Undergraduate courses in electrical machines often include an introduction to their magnetic circuits and to the various magnetic materials used in their construction and their properties. The students must learn to be able to recognize and compare the permeability, saturation, and losses of these magnetic materials, relate each material to its…

Method and apparatus for detecting flaws in conductive material

DOEpatents

Hockey, Ronald L.; Riechers, Douglas M.

1998-01-01

The present invention uses a magnet in relative motion to a conductive material, and a coil that is stationary with respect to the magnet to measure perturbation or variation in the magnetic field in the presence of an inclusion. The magnet and coil sensor may be on the same side of the conductive material.

Conventional magnetic superconductors

DOE PAGES

Wolowiec, C. T.; White, B. D.; Maple, M. B.

2015-07-01

We discuss several classes of conventional magnetic superconductors including the ternary rhodium borides and molybdenum chalcogenides (or Chevrel phases), and the quaternary nickel-borocarbides. These materials exhibit some exotic phenomena related to the interplay between superconductivity and long-range magnetic order including: the coexistence of superconductivity and antiferromagnetic order; reentrant and double reentrant superconductivity, magnetic field induced superconductivity, and the formation of a sinusoidally-modulated magnetic state that coexists with superconductivity. We introduce the article with a discussion of the binary and pseudobinary superconducting materials containing magnetic impurities which at best exhibit short-range “glassy” magnetic order. Early experiments on these materials led tomore » the idea of a magnetic exchange interaction between the localized spins of magnetic impurity ions and the spins of the conduction electrons which plays an important role in understanding conventional magnetic superconductors. Furthermore, these advances provide a natural foundation for investigating unconventional superconductivity in heavy-fermion compounds, cuprates, and other classes of materials in which superconductivity coexists with, or is in proximity to, a magnetically-ordered phase.« less

Interactive modeling-synthesis-characterization approach towards controllable in situ self-assembly of artificial pinning centers in RE-123 films

NASA Astrophysics Data System (ADS)

Wu, Judy; Shi, Jack

2017-10-01

Raising critical current density J c in high temperature superconductors (HTSs) is an important strategy towards performance-cost balanced HTS technology for commercialization. The development of strong nanoscale artificial pinning centers (APCs) in HTS, such as YBa2Cu3O7 or RE-123 in general, represents one of the most exciting progressions in HTS material research in the last decade. Significantly raised J c has been demonstrated in APC/RE-123 nanocomposites by enhanced pinning on magnetic vortices in magnetic fields towards that demanded in practical applications. Among other processes, strain-mediated self-organization has been explored extensively for in situ formation of the APCs based on fundamental physics design rules. The desire in controlling the morphology, dimension, orientation, and concentration of APCs has led to a fundamental question on how strains interact in determining APCs at a macroscopic scale. Answering this question demands an interactive modeling-synthesis-characterization approach towards a thorough understanding of fundamental physics governing the strain-mediated self-organization of the APCs in the APC/RE-123 nanocomposites. Such an understanding is the key for a leap forward from the traditionally empirical method to materials-by-design to enable an optimal APC landscape to be achieved in epitaxial films of APC/YBCO nanocomposites under a precise guidance of fundamental physics. The paper intends to provide a review of recent progress made in the controllable generation of APCs using the interactive modeling-synthesis-characterization approach. The emphasis will be given to the understanding so far achieved using such an approach on the collective effect of the strain field on the morphology, dimension, and orientation of APCs in epitaxial APC/RE-123 nanocomposite films.

A study of the suitability of ferrite for use in low-field insertion devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, K.; Hassenzahl, W.V.

1995-02-01

Most insertion devices built to date use rare-earth permanent-magnet materials, which have a high remanent field and are more expensive than many other permanent-magnet materials. Low-field insertion devices could use less-expensive, lower performance magnetic materials if they had suitable magnetic characteristics. These materials must be resistant to demagnetization during construction and operation of the insertion device, have uniform magnetization, possess low minor-axis magnetic moments, and have small minor field components on the surfaces. This paper describes an investigation to determine if ferrite possesses magnetic qualities suitable for insertion device applications. The type of ferrite investigated, MMPA Ceramic 8 from Stackpolemore » Inc., was found to be acceptable for insertion device applications.« less

3-Dimensional Magnetic Resonance Spectroscopic Imaging at 3 Tesla for Early Response Assessment of Glioblastoma Patients During External Beam Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muruganandham, Manickam; Clerkin, Patrick P.; Smith, Brian J.

Purpose: To evaluate the utility of 3-dimensional magnetic resonance (3D-MR) proton spectroscopic imaging for treatment planning and its implications for early response assessment in glioblastoma multiforme. Methods and Materials: Eighteen patients with newly diagnosed, histologically confirmed glioblastoma had 3D-MR proton spectroscopic imaging (MRSI) along with T2 and T1 gadolinium-enhanced MR images at simulation and at boost treatment planning after 17 to 20 fractions of radiation therapy. All patients received standard radiation therapy (RT) with concurrent temozolomide followed by adjuvant temozolomide. Imaging for response assessment consisted of MR scans every 2 months. Progression-free survival was defined by the criteria of MacDonald et al.more » MRSI images obtained at initial simulation were analyzed for choline/N-acetylaspartate ratios (Cho/NAA) on a voxel-by-voxel basis with abnormal activity defined as Cho/NAA ≥2. These images were compared on anatomically matched MRSI data collected after 3 weeks of RT. Changes in Cho/NAA between pretherapy and third-week RT scans were tested using Wilcoxon matched-pairs signed rank tests and correlated with progression-free survival, radiation dose and location of recurrence using Cox proportional hazards regression. Results: After a median follow-up time of 8.6 months, 50% of patients had experienced progression based on imaging. Patients with a decreased or stable mean or median Cho/NAA values had less risk of progression (P<.01). Patients with an increase in mean or median Cho/NAA values at the third-week RT scan had a significantly greater chance of early progression (P<.01). An increased Cho/NAA at the third-week MRSI scan carried a hazard ratio of 2.72 (95% confidence interval, 1.10-6.71; P=.03). Most patients received the prescription dose of RT to the Cho/NAA ≥2 volume, where recurrence most often occurred. Conclusion: Change in mean and median Cho/NAA detected at 3 weeks was a significant predictor of early progression. The potential impact for risk-adaptive therapy based on early spectroscopic findings is suggested.« less

Engineered materials for all-optical helicity-dependent magnetic switching

NASA Astrophysics Data System (ADS)

Mangin, S.; Gottwald, M.; Lambert, C.-H.; Steil, D.; Uhlíř, V.; Pang, L.; Hehn, M.; Alebrand, S.; Cinchetti, M.; Malinowski, G.; Fainman, Y.; Aeschlimann, M.; Fullerton, E. E.

2014-03-01

The possibility of manipulating magnetic systems without applied magnetic fields have attracted growing attention over the past fifteen years. The low-power manipulation of the magnetization, preferably at ultrashort timescales, has become a fundamental challenge with implications for future magnetic information memory and storage technologies. Here we explore the optical manipulation of the magnetization in engineered magnetic materials. We demonstrate that all-optical helicity-dependent switching (AO-HDS) can be observed not only in selected rare earth-transition metal (RE-TM) alloy films but also in a much broader variety of materials, including RE-TM alloys, multilayers and heterostructures. We further show that RE-free Co-Ir-based synthetic ferrimagnetic heterostructures designed to mimic the magnetic properties of RE-TM alloys also exhibit AO-HDS. These results challenge present theories of AO-HDS and provide a pathway to engineering materials for future applications based on all-optical control of magnetic order.

Characterization of magnetic material in the mound-building termite Macrotermes gilvus in Southeast Asia

NASA Astrophysics Data System (ADS)

Esa, Mohammad Faris Mohammad; Rahim, Faszly; Hassan, Ibrahim Haji; Hanifah, Sharina Abu

2015-09-01

Magnetic material such as magnetite are known as particles that respond to external magnetic field with their ferromagnetic properties as they are believed contribute to in responding to the geomagnetic field. These particles are used by terrestrial animals such as termites for navigation and orientation. Since our earth react as giant magnetic bar, the magnitude of this magnetic field present by intensity and direction (inclination and direction). The magnetic properties and presence of magnetite in termites Macrotermes gilvus, common mound-building termite were tested. M. gilvus termites was tested with a Vibrating Sample Magnetometer VSM to determine the magnetic properties of specimen. The crushed body sample was characterized with X-Ray Diffraction XRD to show the existent of magnetic material (magnetite) in the specimens. Results from VSM indicate that M. gilvus has diamagnetism properties. The characterization by XRD shows the existent of magnetic material in our specimen in low concentration.

Effect of Low Doped Calcium on the Magnetic Properties of La0.7Ba0.297Ca0.003MnO3 for Magnetocaloric Application

NASA Astrophysics Data System (ADS)

Kurniawan, B.; Winarsih, S.; Komala, T.

2018-04-01

Effect of low doped calcium concentration to the magnetic properties of La0.7Ba0.3MnO3 material has been reported in this paper. This compound was chosen because it has high potential to be applied in electronic devices. The most intensive research in the last decade is about magnetocaloric effect (MCE). Magnetic refrigeration will replace Freon R12 that is used in conventional refrigeration with magnetic material which has MCE properties. It is due to conventional refrigeration produce chlorofluorocarbons (CFC) and hydrochlorofluorocarbons (HCFCs) gases which causes ozone depletion. The magnetic measurement was performed by using Vibrating Sample Magnetometer in the range of temperature between 300-400 K under external magnetic field until 20 kOe. By using derivative of magnetization as a function of temperature of the material’s result, Curie temperature (Tc ) of the material is 332.7 K. By using equation (5) for calculating magnetic field dependence of magnetization at various temperature result, magnetic entropy change value (ΔSM ) of the material can be obtained. The ΔSM of the material is -2.928 Jkg-1K-1. The material has highest magnetic entropy change value around its Tc . It is due to there is strong lattice spin coupling around its Tc and would be weak at below and above its Tc .

Current driven dynamics of magnetic domain walls in permalloy nanowires

NASA Astrophysics Data System (ADS)

Hayashi, Masamitsu

The significant advances in micro-fabrication techniques opened the door to access interesting properties in solid state physics. With regard to magnetic materials, geometrical confinement of magnetic structures alters the defining parameters that govern magnetism. For example, development of single domain nano-pillars made from magnetic multilayers led to the discovery of electrical current controlled magnetization switching, which revealed the existence of spin transfer torque. Magnetic domain walls (DWs) are boundaries in magnetic materials that divide regions with distinct magnetization directions. DWs play an important role in the magnetization reversal processes of both bulk and thin film magnetic materials. The motion of DW is conventionally controlled by magnetic fields. Recently, it has been proposed that spin polarized current passed across the DW can also control the motion of DWs. Current in most magnetic materials is spin-polarized, due to spin-dependent scattering of the electrons, and thus can deliver spin angular momentum to the DW, providing a "spin transfer" torque on the DW which leads to DW motion. In addition, owing to the development of micro-fabrication techniques, geometrical confinement of magnetic materials enables creation and manipulation of a "single" DW in magnetic nanostructures. New paradigms for DW-based devices are made possible by the direct manipulation of DWs using spin polarized electrical current via spin transfer torque. This dissertation covers research on current induced DW motion in magnetic nanowires. Fascinating effects arising from the interplay between DWs with spin polarized current will be revealed.

Research on magnetic materials of interest in transportation

DOT National Transportation Integrated Search

2000-04-01

This paper reports the results of an investigation on magnetic materials of interest in the transportation field. It includes information about the present state of magnetic materials and examines the recently discovered phenomenon referred to as col...

Using Ferromagnetic Material to Extend and Shield the Magnetic Field of a Coil

DTIC Science & Technology

2017-06-14

ARL-MR-0954 ● Jun 2017 US Army Research Laboratory Using Ferromagnetic Material to Extend and Shield the Magnetic Field of a...to Extend and Shield the Magnetic Field of a Coil by W Casey Uhlig Weapons and Materials Research Directorate, ARL...Using Ferromagnetic Material to Extend and Shield the Magnetic Field of a Coil 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER

Microinjected magnetic beads induce curvature in Chara rhizoids

NASA Astrophysics Data System (ADS)

Scherp, P.; Hasenstein, K.

The gravitropic response of the Chara rhizoid is based on the interaction between the statoliths and the actin network located in the rhizoid apex. The rhizoid represents a model system for the study of gravitropism, because its apical cell contains the gravity sensing and response mechanism. In order to study the function of the statoliths and the cytoskeleton, we supplemented the naturally occurring statoliths with magnetic beads. These beads can be moved by an external magnetic field and they can be coated to interact with the cytoskeleton. The magnetic beads (1μm diameter) were injected close to the tip of the rhizoid in the presence of an external osmoticum to offset turgor pressure. The injection caused the formation of a noticeable plug of dense material at the site of impalement. After a recovery period of ca. 2 - 4 hours, the whole plant was mounted on the rotatable stage of a custom- built horizontal microscope, equipped with a long-working distance objective and a video camera. This stage is designed to reorientate the cell and/or the injected beads. In order to study the effect of the displacement of magnetic beads, an external magnetic field was applied. This external field was capable of displacing the magnetic particles but did not affect the natural statoliths. Work is in progress to quantify the response, to study the effect of microinjection on wall formation, and utilize coating of the beads to investigate their possible interaction with the original statoliths and with the microfilament network. Supported by NASA grant NAG 2- 1423.

Study of Magnetic Damping Effect on Convection and Solidification Under G-Jitter Conditions

NASA Technical Reports Server (NTRS)

Li, Ben Q.; deGroh, H. C.

2001-01-01

As shown in space flight experiments, g-jitter is a critical issue affecting solidification processing of materials in microgravity. This study aims to provide, through extensive numerical simulations and ground based experiments, an assessment of the use of magnetic fields in combination with microgravity to reduce the g-jitter induced convective flows in space processing systems. Analytical solutions and 2-D and 3-D numerical models for g-jitter driven flows in simple solidification systems with and without the presence of an applied magnetic field have been developed and extensive analyses were carried out. A physical model was also constructed and PIV measurements compared reasonably well with predictions from numerical models. Some key points may be summarized as follows: (1) the amplitude of the oscillating velocity decreases at a rate inversely proportional to the g-jitter frequency and with an increase in the applied magnetic field; (2) the induced flow oscillates at approximately the same frequency as the affecting g-jitter, but out of a phase angle; (3) the phase angle is a complicated function of geometry, applied magnetic field, temperature gradient and frequency; (4) g-jitter driven flows exhibit a complex fluid flow pattern evolving in time; (5) the damping effect is more effective for low frequency flows; and (6) the applied magnetic field helps to reduce the variation of solutal distribution along the solid-liquid interface. Work in progress includes developing numerical models for solidification phenomena with the presence of both g-jitter and magnetic fields and developing a ground-based physical model to verify numerical predictions.

Characterization and Modeling of Materials Responsible for Planetary Crustal Magnetism

NASA Astrophysics Data System (ADS)

Strauss, Becky E.

Earth and Mercury are the only terrestrial planets in our solar system with present-day magnetic dipole fields generated by internal dynamo systems. In contrast, Mars and the Moon show evidence of past dipole fields in the form of crustal magnetic anomalies; to hold measurable magnetizations, crustal materials must have been exposed to an applied field. While the physical principles of magnetic recording are consistent between terrestrial planets, the particular conditions at each planet control the mechanisms by which crustal materials may be magnetized and limit the types of minerals that can retain magnetic remanence. As the suite of magnetic materials used for studies of remanence expands, the need for new methods follows. The integration of rock magnetic techniques with microscopy and chemical analyses enables the reconstruction of increasingly comprehensive narratives of remanence acquisition and alteration, even in materials that are challenging to study using traditional methods. This thesis demonstrates the utility of a materials approach to rock magnetism by applying techniques designed for terrestrial use in a planetary context. The first of two case studies focuses on calcite cave deposits as a means to demonstrate how novel techniques can be used to unlock previously inaccessible archives of magnetic information. Tandem magnetic and microscopic analyses improve our understanding of the rock magnetic properties of weakly magnetic stalagmites and their potential for paleomagnetic research, as well as illuminating the pathways of remanence acquisition in cave systems. The second case study addresses the magnetic anomalies recently detected by the MESSENGER orbiter at Mercury. These anomalies are consistent with remanence acquired in a dipole field. However, in the absence of physical samples, the types of magnetic minerals that could be holding remanence in Mercury's hot, highly reducing surface environment have not yet been determined. Orbital data is combined with fundamental rock magnetic principles to constrain the magnetic mineralogy of Mercury and to propose mechanisms of magnetization and remagnetization in the lithosphere.

Insulator coated magnetic nanoparticulate composites with reduced core loss and method of manufacture thereof

NASA Technical Reports Server (NTRS)

Zhang, Yide (Inventor); Wang, Shihe (Inventor); Xiao, Danny (Inventor)

2004-01-01

A series of bulk-size magnetic/insulating nanostructured composite soft magnetic materials with significantly reduced core loss and its manufacturing technology. This insulator coated magnetic nanostructured composite is comprises a magnetic constituent, which contains one or more magnetic components, and an insulating constituent. The magnetic constituent is nanometer scale particles (1-100 nm) coated by a thin-layered insulating phase (continuous phase). While the intergrain interaction between the immediate neighboring magnetic nanoparticles separated by the insulating phase (or coupled nanoparticles) provide the desired soft magnetic properties, the insulating material provides the much demanded high resistivity which significantly reduces the eddy current loss. The resulting material is a high performance magnetic nanostructured composite with reduced core loss.

Apparatus and method for materials processing utilizing a rotating magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muralidharan, Govindarajan; Angelini, Joseph A.; Murphy, Bart L.

An apparatus for materials processing utilizing a rotating magnetic field comprises a platform for supporting a specimen, and a plurality of magnets underlying the platform. The plurality of magnets are configured for rotation about an axis of rotation intersecting the platform. A heat source is disposed above the platform for heating the specimen during the rotation of the plurality of magnets. A method for materials processing utilizing a rotating magnetic field comprises providing a specimen on a platform overlying a plurality of magnets; rotating the plurality of magnets about an axis of rotation intersecting the platform, thereby applying a rotatingmore » magnetic field to the specimen; and, while rotating the plurality of magnets, heating the specimen to a desired temperature.« less

Method and apparatus for detecting flaws in conductive material

DOEpatents

Hockey, R.L.; Riechers, D.M.

1998-07-07

The present invention uses a magnet in relative motion to a conductive material, and a coil that is stationary with respect to the magnet to measure perturbation or variation in the magnetic field in the presence of an inclusion. The magnet and coil sensor may be on the same side of the conductive material. 18 figs.

Nano Superconducting Quantum Interference device: A powerful tool for nanoscale investigations

NASA Astrophysics Data System (ADS)

Granata, Carmine; Vettoliere, Antonio

2016-02-01

The magnetic sensing at nanoscale level is a promising and interesting research topic of nanoscience. Indeed, magnetic imaging is a powerful tool for probing biological, chemical and physical systems. The study of small spin cluster, like magnetic molecules and nanoparticles, single electron, cold atom clouds, is one of the most stimulating challenges of applied and basic research of the next years. In particular, the magnetic nanoparticle investigation plays a fundamental role for the modern material science and its relative technological applications like ferrofluids, magnetic refrigeration and biomedical applications, including drug delivery, hyper-thermia cancer treatment and magnetic resonance imaging contrast-agent. Actually, one of the most ambitious goals of the high sensitivity magnetometry is the detection of elementary magnetic moment or spin. In this framework, several efforts have been devoted to the development of a high sensitivity magnetic nanosensor pushing sensing capability to the individual spin level. Among the different magnetic sensors, Superconducting QUantum Interference Devices (SQUIDs) exhibit an ultra high sensitivity and are widely employed in numerous applications. Basically, a SQUID consists of a superconducting ring (sensitive area) interrupted by two Josephson junctions. In the recent years, it has been proved that the magnetic response of nano-objects can be effectively measured by using a SQUID with a very small sensitive area (nanoSQUID). In fact, the sensor noise, expressed in terms of the elementary magnetic moment (spin or Bohr magneton), is linearly dependent on the SQUID loop side length. For this reason, SQUIDs have been progressively miniaturized in order to improve the sensitivity up to few spin per unit of bandwidth. With respect to other techniques, nanoSQUIDs offer the advantage of direct measurement of magnetization changes in small spin systems. In this review, we focus on nanoSQUIDs and its applications. In particular, we will discuss the motivations, the theoretical aspects, the fabrication techniques, the different nanoSQUIDs and the relative nanoscale applications.

Science and Technology of Nanostructured Magnetic Materials

DTIC Science & Technology

1990-07-06

galvano-magnetic and magneto-optic effects that can lead to future storage technologies. Ultrafine particles also show interesting and unique properties...areas including thin films, multilayers, disordered systems, ultrafine particles , intermetallic compounds, permanent magnets and magnetic imaging... ultrafine particles , intermetallic compounds, permanent magnets and magnetic imaging techniques. The development of new techniques for materials preparation

Effects of humidity on the magnetic and woody characteristics of powder-type magnetic wood

NASA Astrophysics Data System (ADS)

Oka, H.; Tokuta, H.; Namizaki, Y.; Sekino, N.

2004-05-01

Among three types of proposed magnetic wood, powder-type magnetic wood can be made of recycled magnetic materials from IT devices, consumer electronics and waste wood. Because of its wood powder content, powder-type magnetic wood shows special characteristics different from those of typical magnetic materials. We focused on the relationship between humidity and magnetic characteristics of powder-type magnetic wood. The magnetic powder ratio, wood powder density and magnetic binder density were all examined as parameters for AC permeability.

Progress in nanotechnology for healthcare.

PubMed

Raffa, V; Vittorio, O; Riggio, C; Cuschieri, A

2010-06-01

This review based on the Wickham lecture given by AC at the 2009 SMIT meeting in Sinaia outlines the progress made in nano-technology for healthcare. It describes in brief the nature of nano-materials and their unique properties which accounts for the significant research both in scientific institutions and industry for translation into new therapies embodied in the emerging field of nano-medicine. It stresses that the potential of nano-medicine to make significant inroads for more effective therapies both for life-threatening and life-disabling disorders will only be achieved by high-quality life science research. The first generation of passive nano-diagnostics based on nanoparticle contrast agents for magnetic resonance imaging is well established in clinical practice and new such contrast agents are undergoing early clinical evaluation. Likewise active (second generation) nano-therapies, exemplified by targeted control drug release systems are undergoing early clinical evaluation. The situation concerning other nano-materials such as carbon nanotubes (CNTs) and boron nitride nanotubes (BNNTs) is less advanced although considerable progress has been made on their coating for aqueous dispersion and functionalisation to enable carriage of drugs, genes and fluorescent markers. The main problem related to the clinical use of these nanotubes is that there is no consent among scientists on the fate of such nano-materials following injection or implantation in humans. Provided carbon nanotubes are manufactured to certain medical criteria (length around 1 mum, purity of 97-99% and low Fe content) they exhibit no cytotoxicity on cell cultures and demonstrate full bio-compatibility on in vivo animal studies. The results of recent experimental studies have demonstrated the potential of technologies based on CNTs for low voltage wireless electro-chemotherapy of tumours and for electro-stimulation therapies for cardiac, neurodegenerative and skeletal and visceral muscle disorders.

Neuroinflammation and its relationship to changes in brain volume and white matter lesions in multiple sclerosis.

PubMed

Datta, Gourab; Colasanti, Alessandro; Rabiner, Eugenii A; Gunn, Roger N; Malik, Omar; Ciccarelli, Olga; Nicholas, Richard; Van Vlierberghe, Eline; Van Hecke, Wim; Searle, Graham; Santos-Ribeiro, Andre; Matthews, Paul M

2017-11-01

Brain magnetic resonance imaging is an important tool in the diagnosis and monitoring of multiple sclerosis patients. However, magnetic resonance imaging alone provides limited information for predicting an individual patient's disability progression. In part, this is because magnetic resonance imaging lacks sensitivity and specificity for detecting chronic diffuse and multi-focal inflammation mediated by activated microglia/macrophages. The aim of this study was to test for an association between 18 kDa translocator protein brain positron emission tomography signal, which arises largely from microglial activation, and measures of subsequent disease progression in multiple sclerosis patients. Twenty-one patients with multiple sclerosis (seven with secondary progressive disease and 14 with a relapsing remitting disease course) underwent T1- and T2-weighted and magnetization transfer magnetic resonance imaging at baseline and after 1 year. Positron emission tomography scanning with the translocator protein radioligand 11C-PBR28 was performed at baseline. Brain tissue and lesion volumes were segmented from the T1- and T2-weighted magnetic resonance imaging and relative 11C-PBR28 uptake in the normal-appearing white matter was estimated as a distribution volume ratio with respect to a caudate pseudo-reference region. Normal-appearing white matter distribution volume ratio at baseline was correlated with enlarging T2-hyperintense lesion volumes over the subsequent year (ρ = 0.59, P = 0.01). A post hoc analysis showed that this association reflected behaviour in the subgroup of relapsing remitting patients (ρ = 0.74, P = 0.008). By contrast, in the subgroup of secondary progressive patients, microglial activation at baseline was correlated with later progression of brain atrophy (ρ = 0.86, P = 0.04). A regression model including the baseline normal-appearing white matter distribution volume ratio, T2 lesion volume and normal-appearing white matter magnetization transfer ratio for all of the patients combined explained over 90% of the variance in enlarging lesion volume over the subsequent 1 year. Glial activation in white matter assessed by translocator protein PET significantly improves predictions of white matter lesion enlargement in relapsing remitting patients and is associated with greater brain atrophy in secondary progressive disease over a period of short term follow-up. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Beam loss reduction by magnetic shielding using beam pipes and bellows of soft magnetic materials

NASA Astrophysics Data System (ADS)

Kamiya, J.; Ogiwara, N.; Hotchi, H.; Hayashi, N.; Kinsho, M.

2014-11-01

One of the main sources of beam loss in high power accelerators is unwanted stray magnetic fields from magnets near the beam line, which can distort the beam orbit. The most effective way to shield such magnetic fields is to perfectly surround the beam region without any gaps with a soft magnetic high permeability material. This leads to the manufacture of vacuum chambers (beam pipes and bellows) with soft magnetic materials. A Ni-Fe alloy (permalloy) was selected for the material of the pipe parts and outer bellows parts, while a ferritic stainless steel was selected for the flanges. An austenitic stainless steel, which is non-magnetic material, was used for the inner bellows for vacuum tightness. To achieve good magnetic shielding and vacuum performances, a heat treatment under high vacuum was applied during the manufacturing process of the vacuum chambers. Using this heat treatment, the ratio of the integrated magnetic flux density along the beam orbit between the inside and outside of the beam pipe and bellows became small enough to suppress beam orbit distortion. The outgassing rate of the materials with this heat treatment was reduced by one order magnitude compared to that without heat treatment. By installing the beam pipes and bellows of soft magnetic materials as part of the Japan Proton Accelerator Research Complex 3 GeV rapid cycling synchrotron beam line, the closed orbit distortion (COD) was reduced by more than 80%. In addition, a 95.5% beam survival ratio was achieved by this COD improvement.

Using magnetic charge to understand soft-magnetic materials

NASA Astrophysics Data System (ADS)

Arrott, Anthony S.; Templeton, Terry L.

2018-04-01

This is an overview of what the Landau-Lifshitz-Gilbert equations are doing in soft-magnetic materials with dimensions large compared to the exchange length. The surface magnetic charges try to cancel applied magnetic fields inside the soft magnetic material. The exchange energy tries to reach a minimum while meeting the boundary conditions set by the magnetic charges by using magnetization patterns that have a curl but no divergence. It can almost do this, but it still pays to add some divergence to further lower the exchange energy. There are then both positively and negatively charged regions in the bulk. The unlike charges attract one another, but do not annihilate because they are paid for by the reduction in exchange energy. The micromagnetics of soft magnetic materials is about how those charges rearrange themselves. The topology of magnetic charge distributions presents challenges for mathematicians. No one guessed that they like to form helical patterns of extended multiples of charge density.

Commercial-scale recycling of NdFeB-type magnets with grain boundary modification yields products with 'designer properties' that exceed those of starting materials.

PubMed

Zakotnik, M; Tudor, C O

2015-10-01

NdFeB-type magnets dominate the market for high performance magnetic materials, yet production of 'virgin' magnets via mining is environmentally, financially and energetically costly. Hence, interest is growing in 'magnet to magnet' recycling schemes that offer the potential for cheaper, more environmentally-friendly solutions to the world's growing appetite for rare-earth based magnetic materials. Unfortunately, previously described recycling processes only partially capitalise on this potential, because the methods described to date are limited to 'laboratory scale' or operate only under ideal conditions and result in products that fail to recapture the coercivity of the starting, scrap materials. Herein, we report a commercial scale process (120 kg batches) that completely recovers the properties of the starting scrap magnets. Indeed, 'grain boundary modification', via careful addition of a proprietary mix of blended elements, produces magnets with 'designer properties' that can exceed those of the starting materials and can be closely tailored to meet a wide variety of end-user applications, including high-coercivity (>2000 kA/m), sintered magnets suitable for motor applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Magnetic Coulomb phase in the spin ice Ho2Ti2O7.

PubMed

Fennell, T; Deen, P P; Wildes, A R; Schmalzl, K; Prabhakaran, D; Boothroyd, A T; Aldus, R J; McMorrow, D F; Bramwell, S T

2009-10-16

Spin-ice materials are magnetic substances in which the spin directions map onto hydrogen positions in water ice. Their low-temperature magnetic state has been predicted to be a phase that obeys a Gauss' law and supports magnetic monopole excitations: in short, a Coulomb phase. We used polarized neutron scattering to show that the spin-ice material Ho2Ti2O7 exhibits an almost perfect Coulomb phase. Our result proves the existence of such phases in magnetic materials and strongly supports the magnetic monopole theory of spin ice.

Fundamentals of lateral and vertical heterojunctions of atomically thin materials.

PubMed

Pant, Anupum; Mutlu, Zafer; Wickramaratne, Darshana; Cai, Hui; Lake, Roger K; Ozkan, Cengiz; Tongay, Sefaattin

2016-02-21

At the turn of this century, Herbert Kroemer, the 2000 Nobel Prize winner in Physics, famously commented that "the interface is the device". This statement has since opened up unparalleled opportunities at the interface of conventional three-dimensional (3D) materials (H. Kroemer, Quasi-Electric and Quasi-Magnetic Fields in Non-Uniform Semiconductors, RCA Rev., 1957, 18, 332-342). More than a decade later, Sir Andre Geim and Irina Grigorieva presented their views on 2D heterojunctions which further cultivated broad interests in the 2D materials field. Currently, advances in two-dimensional (2D) materials enable us to deposit layered materials that are only one or few unit-cells in thickness to construct sharp in-plane and out-of-plane interfaces between dissimilar materials, and to be able to fabricate novel devices using these cutting-edge techniques. The interface alone, which traditionally dominated overall device performance, thus has now become the device itself. Fueled by recent progress in atomically thin materials, we are now at the ultimate limit of interface physics, which brings to us new and exciting opportunities, with equally demanding challenges. This paper endeavors to provide stalwarts and newcomers a perspective on recent advances in synthesis, fundamentals, applications, and future prospects of a large variety of heterojunctions of atomically thin materials.

Mechanical Response of Elastomers to Magnetic Fields

NASA Technical Reports Server (NTRS)

Munoz, B. C.; Jolly, M. R.

1996-01-01

Elastomeric materials represent an important class of engineering materials, which are widely used to make components of structures, machinery, and devices for vibration and noise control. Elastomeric material possessing conductive or magnetic properties have been widely used in applications such as conductive and magnetic tapes, sensors, flexible permanent magnets, etc. Our interest in these materials has focussed on understanding and controlling the magnitude and directionality of their response to applied magnetic fields. The effect of magnetic fields on the mechanical properties of these materials has not been the subject of many published studies. Our interest and expertise in controllable fluids have given us the foundation to make a transition to controllable elastomers. Controllable elastomers are materials that exhibit a change in mechanical properties upon application of an external stimuli, in this case a magnetic field. Controllable elastomers promise to have more functionality than conventional elastomers and therefore could share the broad industrial application base with conventional elastomers. As such, these materials represent an attractive class of smart materials, and may well be a link that brings the applications of modern control technologies, intelligent structures and smart materials to a very broad industrial area. This presentation will cover our research work in the area of controllable elastomers at the Thomas Lord Research Center. More specifically, the presentation will discuss the control of mechanical properties and mathematical modeling of the new materials prepared in our laboratories along with experiments to achieve adaptive vibration control using the new materials.

Factors Influencing Progressive Failure Analysis Predictions for Laminated Composite Structure

NASA Technical Reports Server (NTRS)

Knight, Norman F., Jr.

2008-01-01

Progressive failure material modeling methods used for structural analysis including failure initiation and material degradation are presented. Different failure initiation criteria and material degradation models are described that define progressive failure formulations. These progressive failure formulations are implemented in a user-defined material model for use with a nonlinear finite element analysis tool. The failure initiation criteria include the maximum stress criteria, maximum strain criteria, the Tsai-Wu failure polynomial, and the Hashin criteria. The material degradation model is based on the ply-discounting approach where the local material constitutive coefficients are degraded. Applications and extensions of the progressive failure analysis material model address two-dimensional plate and shell finite elements and three-dimensional solid finite elements. Implementation details are described in the present paper. Parametric studies for laminated composite structures are discussed to illustrate the features of the progressive failure modeling methods that have been implemented and to demonstrate their influence on progressive failure analysis predictions.

Magnetic Material Arrangement In Apis Mellifera Abdomens

DTIC Science & Technology

2002-04-01

UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP014406 TITLE: Magnetic Material Arrangement In Apis Mellifera Abdomens...Magnetic Material Arrangement In Apis Mellifera Abdomens Darci M. S. Esquivel, Eliane Wajnberg, Geraldo R. Cernicchiaro, Daniel Acosta-Avalos’ and B.E...transition (52 K- 91 K). Hysteresis curves of Apis mellifera abdomens organized parallel and perpendicular to the applied magnetic field were obtained

Wireless sensing system for non-invasive monitoring of attributes of contents in a container

NASA Technical Reports Server (NTRS)

Woodard, Stanley E. (Inventor)

2010-01-01

A wireless sensing system monitors the level, temperature, magnetic permeability and electrical dielectric constant of a non-gaseous material in a container. An open-circuit electrical conductor is shaped to form a two-dimensional geometric pattern that can store and transfer electrical and magnetic energy. The conductor resonates in the presence of a time-varying magnetic field to generate a harmonic response. The conductor is mounted in an environmentally-sealed housing. A magnetic field response recorder wirelessly transmits the time-varying magnetic field to power the conductor, and wirelessly detects the harmonic response that is an indication of at least one of level of the material in the container, temperature of the material in the container, magnetic permeability of the material in the container, and dielectric constant of the material in the container.

Experimental characterization of magnetic materials for the magnetic shielding of cryomodules in particle accelerators

DOE PAGES

Sah, Sanjay; Myneni, Ganapati; Atulasimha, Jayasimha

2015-10-26

The magnetic properties of two important passive magnetic shielding materials (A4K and Amumetal) for accelerator applications, subjected to various processing and heat treatment conditions are studied comprehensively over a wide range of temperatures: from cryogenic to room temperature. Furthermore, we analyze the effect of processing on the extent of degradation of the magnetic properties of both materials and investigate the possibility of restoring these properties by re-annealing.

Using the History of Electricity and Magnetism To Enhance Teaching.

ERIC Educational Resources Information Center

Binnie, Anna

2001-01-01

Explains the properties of charged objects, the nature of an electric charge, and interactions between electricity and magnetism. Suggests that the development of modern ideas about electricity and magnetism were not a linear progression. (Contains 34 references.) (Author/YDS)

Characterization of magnetic nanoparticles using programmed quadrupole magnetic field-flow fractionation

PubMed Central

Williams, P. Stephen; Carpino, Francesca; Zborowski, Maciej

2010-01-01

Quadrupole magnetic field-flow fractionation is a relatively new technique for the separation and characterization of magnetic nanoparticles. Magnetic nanoparticles are often of composite nature having a magnetic component, which may be a very finely divided material, and a polymeric or other material coating that incorporates this magnetic material and stabilizes the particles in suspension. There may be other components such as antibodies on the surface for specific binding to biological cells, or chemotherapeutic drugs for magnetic drug delivery. Magnetic field-flow fractionation (MgFFF) has the potential for determining the distribution of the magnetic material among the particles in a given sample. MgFFF differs from most other forms of field-flow fractionation in that the magnetic field that brings about particle separation induces magnetic dipole moments in the nanoparticles, and these potentially can interact with one another and perturb the separation. This aspect is examined in the present work. Samples of magnetic nanoparticles were analysed under different experimental conditions to determine the sensitivity of the method to variation of conditions. The results are shown to be consistent and insensitive to conditions, although magnetite content appeared to be somewhat higher than expected. PMID:20732895

Magnetic properties measurement of soft magnetic composite material (SOMALOY 700) by using 3-D tester

NASA Astrophysics Data System (ADS)

Asari, Ashraf; Guo, Youguang; Zhu, Jianguo

2017-08-01

Core losses of rotating electrical machine can be predicted by identifying the magnetic properties of the magnetic material. The magnetic properties should be properly measured since there are some variations of vector flux density in the rotating machine. In this paper, the SOMALOY 700 material has been measured under x, y and z- axes flux density penetration by using the 3-D tester. The calibrated sensing coils are used in detecting the flux densities which have been generated by the Labview software. The measured sensing voltages are used in obtaining the magnetic properties of the sample such as magnetic flux density B, magnetic field strength H, hysteresis loop which can be used to calculate the total core loss of the sample. The results of the measurement are analyzed by using the Mathcad software before being compared to another material.

Magnetization reversal modes in fourfold Co nano-wire systems

NASA Astrophysics Data System (ADS)

Blachowicz, T.; Ehrmann, A.

2015-09-01

Magnetic nano-wire systems are, as well as other patterned magnetic structures, of special interest for novel applications, such as magnetic storage media. In these systems, the coupling between neighbouring magnetic units is most important for the magnetization reversal process of the complete system, leading to a variety of magnetization reversal mechanisms. This article examines the influence of the magnetic material on hysteresis loop shape, coercive field, and magnetization reversal modes. While iron nano-wire systems exhibit flat or one-step hysteresis loops, systems consisting of cobalt nano-wires show hysteresis loops with several longitudinal steps and transverse peaks, correlated to a rich spectrum of magnetization reversal mechanisms. We show that changing the material parameters while the system geometry stays identical can lead to completely different hysteresis loops and reversal modes. Thus, especially for finding magnetic nano-systems which can be used as quaternary or even higher-order storage devices, it is rational to test several materials for the planned systems. Apparently, new materials may lead to novel and unexpected behaviour - and can thus result in novel functionalities.

Magnetic Sensors Based on Amorphous Ferromagnetic Materials: A Review

PubMed Central

Morón, Carlos; Cabrera, Carolina; Morón, Alberto; García, Alfonso; González, Mercedes

2015-01-01

Currently there are many types of sensors that are used in lots of applications. Among these, magnetic sensors are a good alternative for the detection and measurement of different phenomena because they are a “simple” and readily available technology. For the construction of such devices there are many magnetic materials available, although amorphous ferromagnetic materials are the most suitable. The existence in the market of these materials allows the production of different kinds of sensors, without requiring expensive manufacture investments for the magnetic cores. Furthermore, these are not fragile materials that require special care, favouring the construction of solid and reliable devices. Another important feature is that these sensors can be developed without electric contact between the measuring device and the sensor, making them especially fit for use in harsh environments. In this review we will look at the main types of developed magnetic sensors. This work presents the state of the art of magnetic sensors based on amorphous ferromagnetic materials used in modern technology: security devices, weapon detection, magnetic maps, car industry, credit cards, etc. PMID:26569244

Magnetic Sensors Based on Amorphous Ferromagnetic Materials: A Review.

PubMed

Morón, Carlos; Cabrera, Carolina; Morón, Alberto; García, Alfonso; González, Mercedes

2015-11-11

Currently there are many types of sensors that are used in lots of applications. Among these, magnetic sensors are a good alternative for the detection and measurement of different phenomena because they are a "simple" and readily available technology. For the construction of such devices there are many magnetic materials available, although amorphous ferromagnetic materials are the most suitable. The existence in the market of these materials allows the production of different kinds of sensors, without requiring expensive manufacture investments for the magnetic cores. Furthermore, these are not fragile materials that require special care, favouring the construction of solid and reliable devices. Another important feature is that these sensors can be developed without electric contact between the measuring device and the sensor, making them especially fit for use in harsh environments. In this review we will look at the main types of developed magnetic sensors. This work presents the state of the art of magnetic sensors based on amorphous ferromagnetic materials used in modern technology: security devices, weapon detection, magnetic maps, car industry, credit cards, etc.

Nondestructive Testing Magnetic Particle RQA/M1-5330.11.

ERIC Educational Resources Information Center

National Aeronautics and Space Administration, Huntsville, AL. George C. Marshall Space Flight Center.

As one in the series of programmed instruction handbooks, prepared by the U. S. space program, home study material is presented in this volume concerning familiarization and orientation on magnetic particle properties. The subject is presented under the following headings: Magnetism, Producing a Magnetic Field, Magnetizing Currents, Materials and…

Simple Experiments to Help Students Understand Magnetic Phenomena

ERIC Educational Resources Information Center

Browne, Kerry; Jackson, David P.

2007-01-01

The principles of magnetism are a common topic in most introductory physics courses, yet curricular materials exploring the behavior of permanent magnets and magnetic materials are surprisingly rare in the literature. We reviewed the literature to see how magnetism is typically covered in introductory textbooks and curricula. We found that while…

Magnetic suspension options for spacecraft inertia-wheel applications

NASA Technical Reports Server (NTRS)

Downer, J. R.

1984-01-01

Design criteria for spacecraft inertia-wheel suspensions are listed. The advantages of magnetic suspensions over other suspension types for spacecraft inertia-wheel applications are cited along with the functions performed by magnetic suspension. The common designs for magnetic suspensions are enumerated. Materials selection of permanent magnets and core materials is considered.

An alternate approach to the production of radioisotopes for nuclear medicine applications

NASA Astrophysics Data System (ADS)

D'Auria, John M.; Keller, Roderich; Ladouceur, Keith; Lapi, Suzanne E.; Ruth, Thomas J.; Schmor, Paul

2013-03-01

There is a growing need for the production of radioisotopes for both diagnostic and therapeutic medical applications. Radioisotopes that are produced using the (n,γ) or (γ,n) reactions, however, typically result in samples with low specific activity (radioactivity/gram) due to the high abundance of target material of the same element. One method to effectively remove the isotopic impurity is electro-magnetic mass separation. An Ion Source Test Facility has been constructed at TRIUMF to develop high-intensity, high-efficiency, reliable ion sources for purification of radioactive isotopes, particularly those used in nuclear medicine. In progress studies are presented.

PHYSICAL BENEFICATION OF LOW-GRADE URANIUM ORES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Butler, J.N.

1958-07-30

Investigations are presented of methods for the physi cal beneficiation of low-grade and other uranium ores. The investlgations which have been in progress since September 1952 cover work done on a variety of natural ores, as well as a certain amount of basic research on mixtures of synthetic or high-grade natural uranium minerais with various gangues. Methods of beneficlation investigated include flotation, wet and dry attroftioning, magnetic separation. electresiatie separation, and misceilaneous minor methods. A rapid, routine method oicolorimeiric determlnation of uranium was also developed in order to facilitaie analyzing of low-grade materials for uranium. This proeedure is presenied inmore » condensed form. (auth)« less

ZnO nanoparticles applied to bioimaging and drug delivery.

PubMed

Xiong, Huan-Ming

2013-10-04

The last decade has seen significant achievements in biomedical diagnosis and therapy at the levels of cells and molecules. Nanoparticles with luminescent or magnetic properties are used as detection probes and drug carriers, both in vitro and in vivo. ZnO nanoparticles, due to their good biocompatibility and low cost, have shown promising potential in bioimaging and drug delivery. The recent exciting progress on the biomedical applications of ZnO-based nanomaterials is reviewed here, along with discussions on the advantages and limitations of these advanced materials and suggestions for improving methods. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An alternate approach to the production of radioisotopes for nuclear medicine applications.

PubMed

D'Auria, John M; Keller, Roderich; Ladouceur, Keith; Lapi, Suzanne E; Ruth, Thomas J; Schmor, Paul

2013-03-01

There is a growing need for the production of radioisotopes for both diagnostic and therapeutic medical applications. Radioisotopes that are produced using the (n,γ) or (γ,n) reactions, however, typically result in samples with low specific activity (radioactivity∕gram) due to the high abundance of target material of the same element. One method to effectively remove the isotopic impurity is electro-magnetic mass separation. An Ion Source Test Facility has been constructed at TRIUMF to develop high-intensity, high-efficiency, reliable ion sources for purification of radioactive isotopes, particularly those used in nuclear medicine. In progress studies are presented.

Development status of a next generation ECRIS: MARS-D at LBNL

DOE PAGES

Xie, D. Z.; Benitez, J. Y.; Hodgkinson, A.; ...

2015-09-29

To demonstrate a Mixed Axial and Radial field System (MARS) as the best magnet scheme for future ECRISs, MARS-D, a demonstrative ECRIS using a NbTi MARS magnet is progressing at Lawrence Berkeley National Laboratory. An optimized MARS design can use either NbTi or Nb 3Sn coils with reduced engineering complexities to construct the needed high-field magnets. The optimized magnet design could enhance MARS-D to a next generation ECRIS by producing minimum-B field maxima of 5.6 T axially and 3.2 T radially for operating frequencies up to 45 GHz. Lastly, in-progress test winding has achieved a milestone demonstrating the fabrication feasibilitymore » of a MARS closed-loop coil.« less

Development status of a next generation ECRIS: MARS-D at LBNL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, D. Z.; Benitez, J. Y.; Hodgkinson, A.

To demonstrate a Mixed Axial and Radial field System (MARS) as the best magnet scheme for future ECRISs, MARS-D, a demonstrative ECRIS using a NbTi MARS magnet is progressing at Lawrence Berkeley National Laboratory. An optimized MARS design can use either NbTi or Nb 3Sn coils with reduced engineering complexities to construct the needed high-field magnets. The optimized magnet design could enhance MARS-D to a next generation ECRIS by producing minimum-B field maxima of 5.6 T axially and 3.2 T radially for operating frequencies up to 45 GHz. Lastly, in-progress test winding has achieved a milestone demonstrating the fabrication feasibilitymore » of a MARS closed-loop coil.« less

Bringing Earth Magnetism Research into the High School Physics Classroom

NASA Astrophysics Data System (ADS)

Smirnov, A. V.; Bluth, G.; Engel, E.; Kurpier, K.; Foucher, M. S.; Anderson, K. L.

2015-12-01

We present our work in progress from an NSF CAREER project that aims to integrate paleomagnetic research and secondary school physics education. The research project is aimed at quantifying the strength and geometry of the Precambrian geomagnetic field. Investigation of the geomagnetic field behavior is crucial for understanding the mechanisms of field generation, and the development of the Earth's atmosphere and biosphere, and can serve as a focus for connecting high-level Earth science research with a standard physics curriculum. High school science teachers have participated in each summer field and research component of the project, gaining field and laboratory research experience, sets of rock and mineral samples, and classroom-tested laboratory magnetism activities for secondary school physics and earth science courses. We report on three field seasons of teacher field experiences and two years of classroom testing of paleomagnetic research materials merged into physics instruction on magnetism. Students were surveyed before and after dedicated instruction for both perceptions and attitude towards earth science in general, then more specifically on earth history and earth magnetism. Students were also surveyed before and after instruction on major earth system and magnetic concepts and processes, particularly as they relate to paleomagnetic research. Most students surveyed had a strongly positive viewpoint towards the study of Earth history and the importance of studying Earth Sciences in general, but were significantly less drawn towards more specific topics such as mineralogy and magnetism. Students demonstrated understanding of Earth model and the basics of magnetism, as well as the general timing of life, atmospheric development, and magnetic field development. However, detailed knowledge such as the magnetic dynamo, how the magnetic field has changed over time, and connections between earth magnetism and the development of an atmosphere remained largely misunderstood even after specific instruction, laboratory activities, and research examples. Ongoing work is examining the effectiveness of specific classroom and laboratory activities on student perceptions and misconceptions - which models work best to develop deeper understanding and appreciation of paleomagnetic research.

Progressive multiple sclerosis: from pathogenic mechanisms to treatment.

PubMed

Correale, Jorge; Gaitán, María I; Ysrraelit, María C; Fiol, Marcela P

2017-03-01

During the past decades, better understanding of relapsing-remitting multiple sclerosis disease mechanisms have led to the development of several disease-modifying therapies, reducing relapse rates and severity, through immune system modulation or suppression. In contrast, current therapeutic options for progressive multiple sclerosis remain comparatively disappointing and challenging. One possible explanation is a lack of understanding of pathogenic mechanisms driving progressive multiple sclerosis. Furthermore, diagnosis is usually retrospective, based on history of gradual neurological worsening with or without occasional relapses, minor remissions or plateaus. In addition, imaging methods as well as biomarkers are not well established. Magnetic resonance imaging studies in progressive multiple sclerosis show decreased blood-brain barrier permeability, probably reflecting compartmentalization of inflammation behind a relatively intact blood-brain barrier. Interestingly, a spectrum of inflammatory cell types infiltrates the leptomeninges during subpial cortical demyelination. Indeed, recent magnetic resonance imaging studies show leptomeningeal contrast enhancement in subjects with progressive multiple sclerosis, possibly representing an in vivo marker of inflammation associated to subpial demyelination. Treatments for progressive disease depend on underlying mechanisms causing central nervous system damage. Immunity sheltered behind an intact blood-brain barrier, energy failure, and membrane channel dysfunction may be key processes in progressive disease. Interfering with these mechanisms may provide neuroprotection and prevent disability progression, while potentially restoring activity and conduction along damaged axons by repairing myelin. Although most previous clinical trials in progressive multiple sclerosis have yielded disappointing results, important lessons have been learnt, improving the design of novel ones. This review discusses mechanisms involved in progressive multiple sclerosis, correlations between histopathology and magnetic resonance imaging studies, along with possible new therapeutic approaches. © The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A mobile ferromagnetic shape detection sensor using a Hall sensor array and magnetic imaging.

PubMed

Misron, Norhisam; Shin, Ng Wei; Shafie, Suhaidi; Marhaban, Mohd Hamiruce; Mailah, Nashiren Farzilah

2011-01-01

This paper presents a mobile Hall sensor array system for the shape detection of ferromagnetic materials that are embedded in walls or floors. The operation of the mobile Hall sensor array system is based on the principle of magnetic flux leakage to describe the shape of the ferromagnetic material. Two permanent magnets are used to generate the magnetic flux flow. The distribution of magnetic flux is perturbed as the ferromagnetic material is brought near the permanent magnets and the changes in magnetic flux distribution are detected by the 1-D array of the Hall sensor array setup. The process for magnetic imaging of the magnetic flux distribution is done by a signal processing unit before it displays the real time images using a netbook. A signal processing application software is developed for the 1-D Hall sensor array signal acquisition and processing to construct a 2-D array matrix. The processed 1-D Hall sensor array signals are later used to construct the magnetic image of ferromagnetic material based on the voltage signal and the magnetic flux distribution. The experimental results illustrate how the shape of specimens such as square, round and triangle shapes is determined through magnetic images based on the voltage signal and magnetic flux distribution of the specimen. In addition, the magnetic images of actual ferromagnetic objects are also illustrated to prove the functionality of mobile Hall sensor array system for actual shape detection. The results prove that the mobile Hall sensor array system is able to perform magnetic imaging in identifying various ferromagnetic materials.

A Mobile Ferromagnetic Shape Detection Sensor Using a Hall Sensor Array and Magnetic Imaging

PubMed Central

Misron, Norhisam; Shin, Ng Wei; Shafie, Suhaidi; Marhaban, Mohd Hamiruce; Mailah, Nashiren Farzilah

2011-01-01

This paper presents a Mobile Hall Sensor Array system for the shape detection of ferromagnetic materials that are embedded in walls or floors. The operation of the Mobile Hall Sensor Array system is based on the principle of magnetic flux leakage to describe the shape of the ferromagnetic material. Two permanent magnets are used to generate the magnetic flux flow. The distribution of magnetic flux is perturbed as the ferromagnetic material is brought near the permanent magnets and the changes in magnetic flux distribution are detected by the 1-D array of the Hall sensor array setup. The process for magnetic imaging of the magnetic flux distribution is done by a signal processing unit before it displays the real time images using a netbook. A signal processing application software is developed for the 1-D Hall sensor array signal acquisition and processing to construct a 2-D array matrix. The processed 1-D Hall sensor array signals are later used to construct the magnetic image of ferromagnetic material based on the voltage signal and the magnetic flux distribution. The experimental results illustrate how the shape of specimens such as square, round and triangle shapes is determined through magnetic images based on the voltage signal and magnetic flux distribution of the specimen. In addition, the magnetic images of actual ferromagnetic objects are also illustrated to prove the functionality of Mobile Hall Sensor Array system for actual shape detection. The results prove that the Mobile Hall Sensor Array system is able to perform magnetic imaging in identifying various ferromagnetic materials. PMID:22346653

Magnetic Materials

DTIC Science & Technology

1985-03-01

provides high magnetic field capabilities. The emphasis, however, has largely been on semiconaucting and superconducting materials. The lab has not...was easily magnetized and demagnetized , whereas iiardened 0reel acted as a permanent magnet , led to the terminology of hard and soBt magnetic ...similar to Alnico, have relatively low magnetization but high coercive fields. They are well suited for uses where the demagnetizing fields are high

Hybrid magnet program at the Francis Bitter National Magnet Laboratory MIT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leupold, M.J.; Weggel, R.J.

1992-01-01

Resistive water-cooled magnets can generate field according to how much power is available. The authors have developed the hybrid concept for generating fields beyond a power limit, up to 45 T. Along the way the authors have progressed through five successively more adventurous designs. This paper chronicles the evolution of hybrid magnets built at the Francis Bitter National Magnet Laboratory.

Superconducting magnet and fabrication method

NASA Technical Reports Server (NTRS)

Israelsson, Ulf E. (Inventor); Strayer, Donald M. (Inventor)

1994-01-01

A method of trapping a field in a block of superconductor material, includes providing (i) a block of material defining a bore, (ii) a high permeability core within the bore that defines a low reluctance path through the bore, (iii) a high permeability external structure on the exterior of the block of material that defines a low reluctance path between opposite ends of the core, and (iv) an electromagnet configured to apply a magnetic field around the high permeability core. The method proceeds by energizing the electromagnet to produce an applied magnetic field around the high permeability core, cooling the block of material sufficiently to render the block of material superconducting, de-energizing the electromagnet to result in a trapped magnetic field, and at least partially removing the low reluctance path defined by the core and the external structure in order to increase the magnetic flux density of the trapped magnetic field.

Progressive freezing of interacting spins in isolated finite magnetic ensembles

NASA Astrophysics Data System (ADS)

Bhattacharya, Kakoli; Dupuis, Veronique; Le-Roy, Damien; Deb, Pritam

2017-02-01

Self-organization of magnetic nanoparticles into secondary nanostructures provides an innovative way for designing functional nanomaterials with novel properties, different from the constituent primary nanoparticles as well as their bulk counterparts. Collective magnetic properties of such complex closed packing of magnetic nanoparticles makes them more appealing than the individual magnetic nanoparticles in many technological applications. This work reports the collective magnetic behaviour of magnetic ensembles comprising of single domain Fe3O4 nanoparticles. The present work reveals that the ensemble formation is based on the re-orientation and attachment of the nanoparticles in an iso-oriented fashion at the mesoscale regime. Comprehensive dc magnetic measurements show the prevalence of strong interparticle interactions in the ensembles. Due to the close range organization of primary Fe3O4 nanoparticles in the ensemble, the spins of the individual nanoparticles interact through dipolar interactions as realized from remnant magnetization measurements. Signature of super spin glass like behaviour in the ensembles is observed in the memory studies carried out in field cooled conditions. Progressive freezing of spins in the ensembles is corroborated from the Vogel-Fulcher fit of the susceptibility data. Dynamic scaling of relaxation reasserted slow spin dynamics substantiating cluster spin glass like behaviour in the ensembles.

Magnetic nanohole superlattices

DOEpatents

Liu, Feng

2013-05-14

A magnetic material is disclosed including a two-dimensional array of carbon atoms and a two-dimensional array of nanoholes patterned in the two-dimensional array of carbon atoms. The magnetic material has long-range magnetic ordering at a temperature below a critical temperature Tc.

Design Issues for Using Magnetic Materials in Radiation Environments at Elevated Temperature

NASA Technical Reports Server (NTRS)

Bowman, Cheryl L.

2013-01-01

One of the challenges of designing motors and alternators for use in nuclear powered space missions is accounting for the effects of radiation. Terrestrial reactor power plants use distance and shielding to minimize radiation damage but space missions must economize volume and mass. Past studies have shown that sufficiently high radiation levels can affect the magnetic response of hard and soft magnetic materials. Theoretical models explaining the radiation-induced degradation have been proposed but not verified. This paper reviews the literature and explains the cumulative effects of temperature, magnetic-load, and radiation-level on the magnetic properties of component materials. Magnetic property degradation is very specific to alloy choice and processing history, since magnetic properties are very much entwined with specific chemistry and microstructural features. However, there is basic theoretical as well as supportive experimental evidence that the negative impact to magnetic properties will be minimal if the bulk temperature of the material is less than fifty percent of the Curie temperature, the radiation flux is low, and the demagnetization field is small. Keywords: Magnets, Permanent Magnets, Power Converters, Nuclear Electric Power Generation, Radiation Tolerance.

Ultra-high speed permanent magnet axial gap alternator with multiple stators

DOEpatents

Hawsey, Robert A.; Bailey, J. Milton

1991-01-01

An ultra-high speed, axial gap alternator that can provide an output to a plurality of loads, the alternator providing magnetic isolation such that operating conditions in one load will not affect operating conditions of another load. This improved alternator uses a rotor member disposed between a pair of stator members, with magnets disposed in each of the rotor member surfaces facing the stator members. The magnets in one surface of the rotor member, which alternate in polarity, are isolated from the magnets in the other surface of the rotor member by a disk of magnetic material disposed between the two sets of magents. In the preferred embodiment, this disk of magnetic material is laminated between two layers of non-magnetic material that support the magnets, and the magnetic material has a peripheral rim that extends to both surfaces of the rotor member to enhance the structural integrity. The stator members are substantially conventional in construction in that equally-spaced and radially-oriented slots are provided, and winding members are laid in these slots. A unit with multiple rotor members and stator members is also described.

User-Defined Material Model for Progressive Failure Analysis

NASA Technical Reports Server (NTRS)

Knight, Norman F. Jr.; Reeder, James R. (Technical Monitor)

2006-01-01

An overview of different types of composite material system architectures and a brief review of progressive failure material modeling methods used for structural analysis including failure initiation and material degradation are presented. Different failure initiation criteria and material degradation models are described that define progressive failure formulations. These progressive failure formulations are implemented in a user-defined material model (or UMAT) for use with the ABAQUS/Standard1 nonlinear finite element analysis tool. The failure initiation criteria include the maximum stress criteria, maximum strain criteria, the Tsai-Wu failure polynomial, and the Hashin criteria. The material degradation model is based on the ply-discounting approach where the local material constitutive coefficients are degraded. Applications and extensions of the progressive failure analysis material model address two-dimensional plate and shell finite elements and three-dimensional solid finite elements. Implementation details and use of the UMAT subroutine are described in the present paper. Parametric studies for composite structures are discussed to illustrate the features of the progressive failure modeling methods that have been implemented.

PREFACE: 3rd International Workshop on Materials Analysis and Processing in Magnetic Fields (MAP3)

NASA Astrophysics Data System (ADS)

Sakka, Yoshio; Hirota, Noriyuki; Horii, Shigeru; Ando, Tsutomu

2009-07-01

The 3rd International Workshop on Materials Analysis and Processing in Materials Fields (MAP3) was held on 14-16 May 2008 at the University of Tokyo, Japan. The first was held in March 2004 at the National High Magnetic Field Laboratory in Tallahassee, USA. Two years later the second took place in Grenoble, France. MAP3 was held at The University of Tokyo International Symposium, and jointly with MANA Workshop on Materials Processing by External Stimulation, and JSPS CORE Program of Construction of the World Center on Electromagnetic Processing of Materials. At the end of MAP3 it was decided that the next MAP4 will be held in Atlanta, USA in 2010. Processing in magnetic fields is a rapidly expanding research area with a wide range of promising applications in materials science. MAP3 focused on the magnetic field interactions involved in the study and processing of materials in all disciplines ranging from physics to chemistry and biology: Magnetic field effects on chemical, physical, and biological phenomena Magnetic field effects on electrochemical phenomena Magnetic field effects on thermodynamic phenomena Magnetic field effects on hydrodynamic phenomena Magnetic field effects on crystal growth Magnetic processing of materials Diamagnetic levitation Magneto-Archimedes effect Spin chemistry Application of magnetic fields to analytical chemistry Magnetic orientation Control of structure by magnetic fields Magnetic separation and purification Magnetic field-induced phase transitions Materials properties in high magnetic fields Development of NMR and MRI Medical application of magnetic fields Novel magnetic phenomena Physical property measurement by Magnetic fields High magnetic field generation> MAP3 consisted of 84 presentations including 16 invited talks. This volume of Journal of Physics: Conference Series contains the proceeding of MAP3 with 34 papers that provide a scientific record of the topics covered by the conference with the special topics (13 papers) in the journal Science and Technology of Advanced Materials. All articles have been refereed by experts in the field. Both of these journals are fully accessible electronically and can be cited and referenced in the usual way. It is our hope that the reader will enjoy and profit from the MAP3 Proceedings. Hitoshi Wada (Kashiwa, Japan) Chair Eric Beaugon (Grenoble, France) Hans J Schneider-Muntau (Tallahassee, USA) Co-chair Advisory Board Shigeo Asai (Nagoya, Japan) Koichi Kitazawa (Tokyo, Japan) Mitsuhiro Motokawa (Sendai, Japan) Shoogo Ueno (Fukuoka, Japan) Robert Tournier (Grenoble, France) Justin Schwartz (Tallahassee, USA) J C Maan (Nijmegen, Netherland) Scientific Committee Yoshifumi Tanimoto (Hiroshima, Japan) Masuhiro Yamaguchi (Yokohama, Japan) Tsunehisa Kimura (Kyoto, Japan) Yoshio Sakka (Tsukuba Japan) Ryoichi Aogaki (Tokyo, Japan) Jyunji Miyakoshi (Hirosaki, Japan) Kazuo Watanabe (Sendai, Japan) James M Valles Jr. (Providence, USA) Joon Pyo Park (Pohang, Korea) Qiang Wang (Shenyang, China) Nicole Pamme (Hull, UK) Sophie Rivoirard (Grenoble, France) P C M Christianen (Nijmegen, Netherland) Local Organizing Committee Isao Yamamoto Masafumi Yamato Shigeru Horii Norihito Sogoshi Masateru Ikehata Noriyuki Hirota Tsutomu Ando Proceedings Editorial Board Yoshio Sakka Noriyuki Hirota Shigeru Horii Tsutomu Ando Conference photograph

Method for deriving information regarding stress from a stressed ferromagnetic material

DOEpatents

Jiles, David C.

1991-04-30

A non-destructive evaluation technique for deriving stress in ferromagnetic materials including deriving anhysteretic and hysteresis magnetization curves for the material in both unstressed and stressed states. The anhysteretic curve is expressed as a Langevin function. The stress is expressed as an equivalent magnetic field dependent on stress and change of magnetostriction with magnetization. By measurement of these bulk magnetic properties, stress can be derived.

Method for deriving information regarding stress from a stressed ferromagnetic material

DOEpatents

Jiles, D.C.

1991-04-30

A nondestructive evaluation technique is disclosed for deriving stress in ferromagnetic materials including deriving anhysteretic and hysteresis magnetization curves for the material in both unstressed and stressed states. The anhysteretic curve is expressed as a Langevin function. The stress is expressed as an equivalent magnetic field dependent on stress and change of magnetostriction with magnetization. By measurement of these bulk magnetic properties, stress can be derived.

Characteristics of Iron Sand Magnetic Material from Bugel Beach, Kulon Progo, Yogyakarta

NASA Astrophysics Data System (ADS)

Fahmiati; Nuryono; Suyanta

2017-02-01

Magnetic material (MM) of iron sands from Bugel Beach, Kulon Progo, Yogyakarta has been prepared and characterized. Magnetic material was separated from iron sands using a permanent magnet followed by treating with sodium hydroxide (NaOH) solution. The magnetic material product was characterized with X-ray Fluorescence, X-ray Diffraction, Fourrier Transform Infrared spectrophotometry, and Vibrating Sample Magnetometer to determine the chemical composition, crystallinity, presence of functional groups and the magnetization, respectively. Results showed that the investigated iron sand contained magnetic materials up to 89.47% (w/w). The main composition of MM included Fe2O3, TiO2, and SiO2, with percentages of 72.6, 7.0, and 10.0%, respectively, and the functional groups of material was dominated with Fe-OH and Fe-O. Treatment with NaOH 4M and NaOH 8M increased the content of Fe2O3 and TiO2, otherwise reduced the concentration of SiO2 and contributed to the improvement of the magnetization from 42.1 to 44.3 emu/g (with 4 M NaOH) and 64.0 emu/g (with 8 M NaOH). Additionally, MM was dominated with mineral of magnetite and contained functional groups of Fe-OH and Fe-O.

Operation of Lanzhou all permanent electron cyclotron resonance ion source No. 2 on 320 kV platform with highly charged ions.

PubMed

Lu, W; Li, J Y; Kang, L; Liu, H P; Li, H; Li, J D; Sun, L T; Ma, X W

2014-02-01

The 320 kV platform for multi-discipline research with highly charged ions is a heavy ion beam acceleration instrument developed by Institute of Modern Physics, which is dedicated to basic scientific researches such as plasma, atom, material physics, and astrophysics, etc. The platform has delivered ion beams of 400 species for 36,000 h. The average operation time is around 5000 h/year. With the beams provided by the platform, lots of outstanding progresses were made in various research fields. The ion source of the platform is an all-permanent magnet electron cyclotron resonance ion source, LAPECR2 (Lanzhou All Permanent ECR ion source No. 2). The maximum axial magnetic fields are 1.28 T at injection and 1.07 T at extraction, and the radial magnetic field is up to 1.21 T at the inner wall of the plasma chamber. The ion source is capable to produce low, medium, and high charge state gaseous and metallic ion beams, such as H(+), (40)Ar(8+), (129)Xe(30+), (209)Bi(33+), etc. This paper will present the latest result of LAPECR2 and the routine operation status for the high voltage platform.

SYNTHESIS of MOLECULE/POLYMER-BASED MAGNETIC MATERIALS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, Joel S.

2016-02-01

We have synthesized and characterized several families of organic-based magnets, a new area showing that organic species can exhibit the technologically important property of magnetic ordering. Thin film magnets with ordering temperatures exceeding room temperature have been exceeded. Hence, organic-based magnets represent a new class of materials that exhibit magnetic ordering and do not require energy-intensive metallurgical processing and are based upon Earth-abundant elements.

Apparatus and method for detecting and/or measuring flaws in conductive material

DOEpatents

Hockey, Ronald L.; Riechers, Douglas M.

2000-01-01

The present invention uses a magnet and sensor coil unilaterial and in relative motion to a conductive material, to measure perturbation or variation in the magnetic field in the presence of a flaw. A liftoff compensator measures a distance between the conductive material and the magnet.

Superlattice structure modeling and simulation of High Electron Mobility Transistor for improved performance

NASA Astrophysics Data System (ADS)

Munusami, Ravindiran; Yakkala, Bhaskar Rao; Prabhakar, Shankar

2013-12-01

Magnetic tunnel junction were made by inserting the magnetic materials between the source, channel and the drain of the High Electron Mobility Transistor (HEMT) to enhance the performance. Material studio software package was used to design the superlattice layers. Different cases were analyzed to optimize the performance of the device by placing the magnetic material at different positions of the device. Simulation results based on conductivity reveals that the device has a very good electron transport due to the magnetic materials and will amplify very low frequency signals.

Magnetic measurement of soft magnetic composites material under 3D SVPWM excitation

NASA Astrophysics Data System (ADS)

Zhang, Changgeng; Jiang, Baolin; Li, Yongjian; Yang, Qingxin

2018-05-01

The magnetic properties measurement and analysis of soft magnetic material under the rotational space-vector pulse width modulation (SVPWM) excitation are key factors in design and optimization of the adjustable speed motor. In this paper, a three-dimensional (3D) magnetic properties testing system fit for SVPWM excitation is built, which includes symmetrical orthogonal excitation magnetic circuit and cubic field-metric sensor. Base on the testing system, the vector B and H loci of soft magnetic composite (SMC) material under SVPWM excitation are measured and analyzed by proposed 3D SVPWM control method. Alternating and rotating core losses under various complex excitation with different magnitude modulation ratio are calculated and compared.

Ultrasound generation with high power and coil only EMAT concepts.

PubMed

Rueter, Dirk; Morgenstern, Tino

2014-12-01

Electro-magnetic acoustic transducers (EMATs) are intended as non-contact and non-destructive ultrasound transducers for metallic material. The transmitted intensities from EMATS are modest, particularly at notable lift off distances. Some time ago a concept for a "coil only EMAT" was presented, without static magnetic field. In this contribution, such compact "coil only EMATs" with effective areas of 1-5cm(2) were driven to excessive power levels at MHz frequencies, using pulsed power technologies. RF induction currents of 10kA and tens of Megawatts are applied. With increasing power the electroacoustic conversion efficiency also increases. The total effect is of second order or quadratic, therefore non-linear and progressive, and yields strong ultrasound signals up to kW/cm(2) at MHz frequencies in the metal. Even at considerable lift off distances (cm) the ultrasound can be readily detected. Test materials are aluminum, ferromagnetic steel and stainless steel (non-ferromagnetic). Thereby, most metal types are represented. The technique is compared experimentally with other non-contact methods: laser pulse induced ultrasound and spark induced ultrasound, both damaging to the test object's surface. At small lift off distances, the intensity from this EMAT concept clearly outperforms the laser pulses or heavy spark impacts. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

EDITORIAL: Message from the Editor

NASA Astrophysics Data System (ADS)

Schüller, F. C.

2005-01-01

The group of 25 articles published in this special issue of Nuclear Fusion aims to monitor the progress made with experiments on fusion physics that have been conducted worldwide up to the end of 2004. These articles are based on overview reports from the various experimental teams presented at the Fusion Energy Conference (FEC 2004). This conference was organized by the IAEA together with the Portuguese host organization CFN-IST and was held in Vilamoura, Portugal, in early November 2004. The overviews presented at the conference have been rewritten and extended for the purpose of this special issue and submitted to the standard double-referee peer-review of Nuclear Fusion. Most teams have made use of this opportunity. Therefore this issue, which also includes four conference summaries, presents a reasonably complete picture of the progress made since FEC 2002 in Lyon. The articles are placed in the following sequence: Conference summaries Theory of magnetic confinement Experimental confinement, plasma-material interactions and innovative concepts Experiments on stability, energetic particles, waves and current drive Inertial confinement fusion Tokamaks Performance: JT-60U, JET, DIII-D, ASDEX-U, C-MOD Steady state/long pulse operation: Tore Supra, HT-7, TRIAM Spherical tokamaks: MAST, NSTX Tritium experiments: JET Diagnostics and heating methods: JET (diagnostics), T-10 (ECRH and diagnostics) and FTU (LHH + ECRH) New devices: HL-2A Small devices Alternative magnetic confinement concepts Stellarators: LHD, TJ-II Reversed field pinches: MST Inertial confinement Direct drive Heavy ion beam fusion Readers will also notice the supplementary issue of the journal (volume 45, issue 10A). This extra issue contains the 15-year overview report on progress in fusion research as written by the International Fusion Research Council (IFRC) under the editorial responsibility of the IFRC. Both issues together will give the interested reader a state-of-the-art picture of the progress in nuclear fusion research.

Nondestructive Evaluation Techniques for Development and Characterization of Carbon Nanotube Based Superstructures

NASA Technical Reports Server (NTRS)

Wincheski, Buzz; Kim, Jae-Woo; Sauti, Godfrey; Wainwright, Elliot; Williams, Phillip; Siochi, Emile J.

2014-01-01

Recently, multiple commercial vendors have developed capability for the production of large-scale quantities of high-quality carbon nanotube sheets and yarns. While the materials have found use in electrical shielding applications, development of structural systems composed of a high volume fraction of carbon nanotubes is still lacking. A recent NASA program seeks to address this by prototyping a structural nanotube composite with strength-toweight ratio exceeding current state-of-the-art carbon fiber composites. Commercially available carbon nanotube sheets, tapes, and yarns are being processed into high volume fraction carbon nanotube-polymer nanocomposites. Nondestructive evaluation techniques have been applied throughout this development effort for material characterization and process control. This paper will report on the progress of these efforts, including magnetic characterization of residual catalyst content, Raman scattering characterization of nanotube diameter, defect ratio, and nanotube strain, and polarized Raman scattering for characterization of nanotube alignment.

Chemical principles underpinning the performance of the metal-organic framework HKUST-1.

PubMed

Hendon, Christopher H; Walsh, Aron

2015-07-15

A common feature of multi-functional metal-organic frameworks is a metal dimer in the form of a paddlewheel, as found in the structure of Cu 3 ( btc ) 2 (HKUST-1). The HKUST-1 framework demonstrates exceptional gas storage, sensing and separation, catalytic activity and, in recent studies, unprecedented ionic and electrical conductivity. These results are a promising step towards the real-world application of metal-organic materials. In this perspective, we discuss progress in the understanding of the electronic, magnetic and physical properties of HKUST-1, representative of the larger family of Cu···Cu containing metal-organic frameworks. We highlight the chemical interactions that give rise to its favourable properties, and which make this material well suited to a range of technological applications. From this analysis, we postulate key design principles for tailoring novel high-performance hybrid frameworks.

Chemical principles underpinning the performance of the metal–organic framework HKUST-1

PubMed Central

Hendon, Christopher H.

2015-01-01

A common feature of multi-functional metal–organic frameworks is a metal dimer in the form of a paddlewheel, as found in the structure of Cu3(btc)2 (HKUST-1). The HKUST-1 framework demonstrates exceptional gas storage, sensing and separation, catalytic activity and, in recent studies, unprecedented ionic and electrical conductivity. These results are a promising step towards the real-world application of metal–organic materials. In this perspective, we discuss progress in the understanding of the electronic, magnetic and physical properties of HKUST-1, representative of the larger family of Cu···Cu containing metal–organic frameworks. We highlight the chemical interactions that give rise to its favourable properties, and which make this material well suited to a range of technological applications. From this analysis, we postulate key design principles for tailoring novel high-performance hybrid frameworks. PMID:28706713

Zeolite-like liquid crystals

NASA Astrophysics Data System (ADS)

Poppe, Silvio; Lehmann, Anne; Scholte, Alexander; Prehm, Marko; Zeng, Xiangbing; Ungar, Goran; Tschierske, Carsten

2015-10-01

Zeolites represent inorganic solid-state materials with porous structures of fascinating complexity. Recently, significant progress was made by reticular synthesis of related organic solid-state materials, such as metal-organic or covalent organic frameworks. Herein we go a step further and report the first example of a fluid honeycomb mimicking a zeolitic framework. In this unique self-assembled liquid crystalline structure, transverse-lying π-conjugated rod-like molecules form pentagonal channels, encircling larger octagonal channels, a structural motif also found in some zeolites. Additional bundles of coaxial molecules penetrate the centres of the larger channels, unreachable by chains attached to the honeycomb framework. This creates a unique fluid hybrid structure combining positive and negative anisotropies, providing the potential for tuning the directionality of anisotropic optical, electrical and magnetic properties. This work also demonstrates a new approach to complex soft-matter self-assembly, by using frustration between space filling and the entropic penalty of chain extension.

Magnetismo Molecular (Molecular Magentism)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reis, Mario S; Moreira Dos Santos, Antonio F

The new synthesis processes in chemistry open a new world of research, new and surprising materials never before found in nature can now be synthesized and, as a wonderful result, observed a series of physical phenomena never before imagined. Among these are many new materials the molecular magnets, the subject of this book and magnetic properties that are often reflections of the quantum behavior of these materials. Aside from the wonderful experience of exploring something new, the theoretical models that describe the behavior these magnetic materials are, in most cases, soluble analytically, which allows us to know in detail themore » physical mechanisms governing these materials. Still, the academic interest in parallel this subject, these materials have a number of properties that are promising to be used in technological devices, such as in computers quantum magnetic recording, magnetocaloric effect, spintronics and many other devices. This volume will journey through the world of molecular magnets, from the structural description of these materials to state of the art research.« less

Optical fiber magnetic field sensors with TbDyFe magnetostrictive thin films as sensing materials.

PubMed

Yang, Minghong; Dai, Jixiang; Zhou, Ciming; Jiang, Desheng

2009-11-09

Different from usually-used bulk magnetostrictive materials, magnetostrictive TbDyFe thin films were firstly proposed as sensing materials for fiber-optic magnetic field sensing characterization. By magnetron sputtering process, TbDyFe thin films were deposited on etched side circle of a fiber Bragg Grating (FBG) as sensing element. There exists more than 45pm change of FBG wavelength when magnet field increase up to 50 mT. The response to magnetic field is reversible, and could be applicable for magnetic and current sensing.

Tailoring superelasticity of soft magnetic materials

NASA Astrophysics Data System (ADS)

Cremer, Peet; Löwen, Hartmut; Menzel, Andreas M.

2015-10-01

Embedding magnetic colloidal particles in an elastic polymer matrix leads to smart soft materials that can reversibly be addressed from outside by external magnetic fields. We discover a pronounced nonlinear superelastic stress-strain behavior of such materials using numerical simulations. This behavior results from a combination of two stress-induced mechanisms: a detachment mechanism of embedded particle aggregates and a reorientation mechanism of magnetic moments. The superelastic regime can be reversibly tuned or even be switched on and off by external magnetic fields and thus be tailored during operation. Similarities to the superelastic behavior of shape-memory alloys suggest analogous applications, with the additional benefit of reversible switchability and a higher biocompatibility of soft materials.

Preliminary Phase Field Computational Model Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yulan; Hu, Shenyang Y.; Xu, Ke

2014-12-15

This interim report presents progress towards the development of meso-scale models of magnetic behavior that incorporate microstructural information. Modeling magnetic signatures in irradiated materials with complex microstructures (such as structural steels) is a significant challenge. The complexity is addressed incrementally, using the monocrystalline Fe (i.e., ferrite) film as model systems to develop and validate initial models, followed by polycrystalline Fe films, and by more complicated and representative alloys. In addition, the modeling incrementally addresses inclusion of other major phases (e.g., martensite, austenite), minor magnetic phases (e.g., carbides, FeCr precipitates), and minor nonmagnetic phases (e.g., Cu precipitates, voids). The focus ofmore » the magnetic modeling is on phase-field models. The models are based on the numerical solution to the Landau-Lifshitz-Gilbert equation. From the computational standpoint, phase-field modeling allows the simulation of large enough systems that relevant defect structures and their effects on functional properties like magnetism can be simulated. To date, two phase-field models have been generated in support of this work. First, a bulk iron model with periodic boundary conditions was generated as a proof-of-concept to investigate major loop effects of single versus polycrystalline bulk iron and effects of single non-magnetic defects. More recently, to support the experimental program herein using iron thin films, a new model was generated that uses finite boundary conditions representing surfaces and edges. This model has provided key insights into the domain structures observed in magnetic force microscopy (MFM) measurements. Simulation results for single crystal thin-film iron indicate the feasibility of the model for determining magnetic domain wall thickness and mobility in an externally applied field. Because the phase-field model dimensions are limited relative to the size of most specimens used in experiments, special experimental methods were devised to create similar boundary conditions in the iron films. Preliminary MFM studies conducted on single and polycrystalline iron films with small sub-areas created with focused ion beam have correlated quite well qualitatively with phase-field simulations. However, phase-field model dimensions are still small relative to experiments thus far. We are in the process of increasing the size of the models and decreasing specimen size so both have identical dimensions. Ongoing research is focused on validation of the phase-field model. Validation is being accomplished through comparison with experimentally obtained MFM images (in progress), and planned measurements of major hysteresis loops and first order reversal curves. Extrapolation of simulation sizes to represent a more stochastic bulk-like system will require sampling of various simulations (i.e., with single non-magnetic defect, single magnetic defect, single grain boundary, single dislocation, etc.) with distributions of input parameters. These outputs can then be compared to laboratory magnetic measurements and ultimately to simulate magnetic Barkhausen noise signals.« less

A three-dimensional finite element evaluation of magnetic attachment attractive force and the influence of the magnetic circuit.

PubMed

Kumano, Hirokazu; Nakamura, Yoshinori; Kanbara, Ryo; Takada, Yukyo; Ochiai, Kent T; Tanaka, Yoshinobu

2014-01-01

The finite element method has been considered to be excellent evaluative technique to study magnetic circuit optimization. The present study analyzed and quantitatively evaluated the different effects of magnetic circuit on attractive force and magnetic flux density using a three-dimensional finite element method for comparative evaluation. The diameter of a non-magnetic material in the shield disk of a magnetic assembly was variably increased by 0.1 mm to a maximum 2.0 mm in this study design. The analysis results demonstrate that attractive force increases until the diameter of the non-magnetic spacing material reaches a diameter of 0.5 mm where it peaks and then decreases as the overall diameter increases over 0.5 mm. The present analysis suggested that the attractive force for a magnetic attachment is optimized with an appropriate magnetic assembly shield disk diameter using a non-magnetic material to effectively change the magnetic circuit efficiency and resulting retention.

Influence of backup bearings and support structure dynamics on the behavior of rotors with active supports

NASA Technical Reports Server (NTRS)

Flowers, George T.

1994-01-01

Progress over the past year includes the following: A simplified rotor model with a flexible shaft and backup bearings has been developed. A simple rotor model which includes a flexible disk and bearings with clearance has been developed and the dynamics of the model investigated. A rotor model based upon the T-501 engine has been developed which includes backup bearing effects. Parallel simulation runs are being conducted using an ANSYS based finite element model of the T-501. The magnetic bearing test rig is currently floating and dynamics/control tests are being conducted. A paper has been written that documents the work using the T-501 engine model. Work has continued with the simplified model. The finite element model is currently being modified to include the effects of foundation dynamics. A literature search for material on foil bearings has been conducted. A finite element model is being developed for a magnetic bearing in series with a foil backup bearing.

Two-year magnetic monitoring in conjunction with geochemical and electron microscopic data of roadside dust in Seoul, Korea

NASA Astrophysics Data System (ADS)

Kim, Wonnyon; Doh, Seong-Jae; Park, Yong-Hee; Yun, Seong-Taek

Mineral magnetic properties of roadside dusts in Seoul, Korea, were measured and compared with the results of geochemical analyses in order to investigate the spatio-temporal patterns of urban pollution. Scanning electron microscope (SEM) observations and energy dispersive X-ray spectroscopy (EDS) analyses were carried out to verify the magnetic materials and their potential sources. A total of 1956 dust samples were collected monthly at eight sites, from June 1998 to June 2000. Thermomagnetic data and SEM observations for magnetic extracts indicated that the major magnetic phase was magnetite-like material. In particular, the highest and the lowest magnetic concentrations were observed in industrial areas and a park area, respectively, whereas, heavy traffic areas showed low to intermediate concentration. A linear correlation between enrichment indexes of magnetic susceptibility and heavy metals suggests that magnetic susceptibility can be used as a proxy for heavy metal pollution. The magnetic concentrations and magnetic particle sizes showed systematic seasonal fluctuations (high and large in winter versus low and small in summer) due to the seasonal influx variations of anthropogenic magnetic materials. On the basis of the morphology and elemental composition, the magnetic materials were grouped into three types: magnetic spherules possibly emitted from factories and domestic heating systems, aggregates derived from vehicle emission or motor vehicle brake system, and angular magnetic particles of natural origin.

Highly stable and finely tuned magnetic fields generated by permanent magnet assemblies.

PubMed

Danieli, E; Perlo, J; Blümich, B; Casanova, F

2013-05-03

Permanent magnetic materials are the only magnetic source that can be used to generate magnetic fields without power consumption or maintenance. Such stand-alone magnets are very attractive for many scientific and engineering areas, but they suffer from poor temporal field stability, which arises from the strong sensitivity of the magnetic materials and mechanical support to temperature variation. In this work, we describe a highly efficient method useful to cancel the temperature coefficient of permanent magnet assemblies in a passive and accurate way. It is based on the combination of at least two units made of magnetic materials with different temperature coefficients arranged in such a way that the ratio of the fields generated by each unit matches the ratio of their effective temperature coefficients defined by both the magnetic and mechanical contributions. Although typically available magnetic materials have negative temperature coefficients, the cancellation is achieved by aligning the fields generated by each unit in the opposite direction. We demonstrate the performance of this approach by stabilizing the field generated by a dipolar Halbach magnet, recently proposed to achieve high field homogeneity. Both the field drift and the homogeneity are monitored via nuclear magnetic resonance spectroscopy experiments. The results demonstrate the compatibility of the thermal compensation approach with existing strategies useful to fine-tune the spatial dependence of the field generated by permanent magnet arrays.

Thermoseeds for interstitial magnetic hyperthermia: from bioceramics to nanoparticles

NASA Astrophysics Data System (ADS)

Baeza, A.; Arcos, D.; Vallet-Regí, M.

2013-12-01

The development of magnetic materials for interstitial hyperthermia treatment of cancer is an ever evolving research field which provides new alternatives to antitumoral therapies. The development of biocompatible magnetic materials has resulted in new biomaterials with multifunctional properties, which are able to adapt to the complex scenario of tumoral processes. Once implanted or injected in the body, magnetic materials can behave as thermoseeds under the effect of AC magnetic fields. Magnetic bioceramics aimed to treat bone tumors and magnetic nanoparticles are among the most studied thermoseeds, and supply different solutions for the different scenarios in cancerous processes. This paper reviews some of the biomaterials used for bone cancer treatment and skeletal reinforcing, as well as the more complex topic of magnetic nanoparticles for intracellular targeting and hyperthermia.

Thermoseeds for interstitial magnetic hyperthermia: from bioceramics to nanoparticles.

PubMed

Baeza, A; Arcos, D; Vallet-Regí, M

2013-12-04

The development of magnetic materials for interstitial hyperthermia treatment of cancer is an ever evolving research field which provides new alternatives to antitumoral therapies. The development of biocompatible magnetic materials has resulted in new biomaterials with multifunctional properties, which are able to adapt to the complex scenario of tumoral processes. Once implanted or injected in the body, magnetic materials can behave as thermoseeds under the effect of AC magnetic fields. Magnetic bioceramics aimed to treat bone tumors and magnetic nanoparticles are among the most studied thermoseeds, and supply different solutions for the different scenarios in cancerous processes. This paper reviews some of the biomaterials used for bone cancer treatment and skeletal reinforcing, as well as the more complex topic of magnetic nanoparticles for intracellular targeting and hyperthermia.

Full magnetization process of 3d-4f hard magnetic materials in ultrahigh magnetic fields (an example: RFe11Ti)

NASA Astrophysics Data System (ADS)

Kuz'min, M. D.; Zvezdin, A. K.

1998-03-01

The prospects of using the free-powder high-field magnetization method for a quantitative study of inter-sublattice exchange interaction in 3d-4f hard magnetic materials are analyzed. Such analysis is stimulated by the availability of pulsed magnetic fields ˜103 T generated by implosion. Particular attention is paid to effects due to magnetic anisotropy, essential for these materials. The 3d-4f ferrimagnets where both sublattices contribute positively to the easy-axis anisotropy are shown to be suitable objects of study by the free-powder method, because (i) anomalies in their low-temperature magnetizatization curves are sharp and (ii) anisotropic effects can be allowed for without quantitative knowledge of the anisotropy constants. Moreover, these "good" hard magnetic materials can be brought into metamagnetic regime by diluting the rare earth sublattice with nonmagnetic yttrium; then, regardless of the anisotropy constants, the magnetization curve at low temperatures has just one steplike anomaly, the threshold field being equal exactly to the molecular field acting on the rare earth.

A Highly Tunable Silicone-Based Magnetic Elastomer with Nanoscale Homogeneity

PubMed Central

Evans, Benjamin A.; Fiser, Briana L.; Prins, Willem J.; Rapp, Daniel J.; Shields, Adam R.; Glass, Daniel R.; Superfine, R.

2011-01-01

Magnetic elastomers have been widely pursued for sensing and actuation applications. Silicone-based magnetic elastomers have a number of advantages over other materials such as hydrogels, but aggregation of magnetic nanoparticles within silicones is difficult to prevent. Aggregation inherently limits the minimum size of fabricated structures and leads to non-uniform response from structure to structure. We have developed a novel material which is a complex of a silicone polymer (polydimethylsiloxane-co-aminopropylmethylsiloxane) adsorbed onto the surface of magnetite (γ-Fe203) nanoparticles 7–10 nm in diameter. The material is homogenous at very small length scales (< 100 nm) and can be crosslinked to form a flexible, magnetic material which is ideally suited for the fabrication of micro- to nanoscale magnetic actuators. The loading fraction of magnetic nanoparticles in the composite can be varied smoothly from 0 – 50% wt. without loss of homogeneity, providing a simple mechanism for tuning actuator response. We evaluate the material properties of the composite across a range of nanoparticle loading, and demonstrate a magnetic-field-induced increase in compressive modulus as high as 300%. Furthermore, we implement a strategy for predicting the optimal nanoparticle loading for magnetic actuation applications, and show that our predictions correlate well with experimental findings. PMID:22184482

A Highly Tunable Silicone-Based Magnetic Elastomer with Nanoscale Homogeneity.

PubMed

Evans, Benjamin A; Fiser, Briana L; Prins, Willem J; Rapp, Daniel J; Shields, Adam R; Glass, Daniel R; Superfine, R

2012-02-01

Magnetic elastomers have been widely pursued for sensing and actuation applications. Silicone-based magnetic elastomers have a number of advantages over other materials such as hydrogels, but aggregation of magnetic nanoparticles within silicones is difficult to prevent. Aggregation inherently limits the minimum size of fabricated structures and leads to non-uniform response from structure to structure. We have developed a novel material which is a complex of a silicone polymer (polydimethylsiloxane-co-aminopropylmethylsiloxane) adsorbed onto the surface of magnetite (γ-Fe(2)0(3)) nanoparticles 7-10 nm in diameter. The material is homogenous at very small length scales (< 100 nm) and can be crosslinked to form a flexible, magnetic material which is ideally suited for the fabrication of micro- to nanoscale magnetic actuators. The loading fraction of magnetic nanoparticles in the composite can be varied smoothly from 0 - 50% wt. without loss of homogeneity, providing a simple mechanism for tuning actuator response. We evaluate the material properties of the composite across a range of nanoparticle loading, and demonstrate a magnetic-field-induced increase in compressive modulus as high as 300%. Furthermore, we implement a strategy for predicting the optimal nanoparticle loading for magnetic actuation applications, and show that our predictions correlate well with experimental findings.

Development of the STPX Spheromak System

NASA Astrophysics Data System (ADS)

Williams, R. L.; Clark, J.; Weatherford, C. A.

2015-11-01

The progress made in starting up the STPX Spheromak system, which is now installed at the Florida A&M University, is reviewed. Experimental, computational and theoretical activities are underway. The control system for firing the magnetized coaxial plasma gun and for collecting data from the diagnostic probes, based on LabView, is being tested and adapted. Preliminary results of testing the installed magnetic field probes, Langmuir triple probes, cylindrical ion probes, and optical diagnostics will be discussed. Progress in modeling this spheromak using simulation codes, such as NIMROD, will be discussed. Progress in investigating the use of algebraic topology to describe this spheromak will be reported.

Magnetic separator having a multilayer matrix, method and apparatus

DOEpatents

Kelland, David R.

1980-01-01

A magnetic separator having multiple staggered layers of porous magnetic material positioned to intercept a fluid stream carrying magnetic particles and so placed that a bypass of each layer is effected as the pores of the layer become filled with material extracted from the fluid stream.

A Dose Escalation and Pharmacodynamic Study of Triapine and Radiation in Patients With Locally Advanced Pancreas Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Ludmila Katherine; Grecula, John; Jia, Guang

2012-11-15

Purpose: Triapine, a novel inhibitor of the M2 subunit of ribonucleotide reductase (RR), is a potent radiosensitizer. This phase 1 study, sponsored by the National Cancer Institute Cancer Therapy Evaluation Program, assessed the safety and tolerability of triapine in combination with radiation (RT) in patients with locally advanced pancreas cancer (LAPCA). Methods and Materials: We evaluated 3 dosage levels of triapine (24 mg/m{sup 2}, 48 mg/m{sup 2}, 72 mg/m{sup 2}) administered with 50.4 Gy of RT in 28 fractions. Patients with LAPCA received triapine thrice weekly, every other week during the course of RT. Dose-limiting toxicity (DLT) was assessed duringmore » RT and for 4 weeks after its completion. Dynamic contrast-enhanced magnetic resonance imaging and serum RR levels were evaluated as potential predictors for early response. Results: Twelve patients were treated. Four patients (1 nonevaluable) were enrolled at dosage level 1 (DL1), 3 patients at DL2, and 5 patients (2 nonevaluable) at DL3. No DLTs were observed, and the maximum tolerated dose was not reached. Two patients (17%) achieved partial response, and 6 patients (50%) had stable disease. One patient underwent R0 resection after therapy. Ninety-two percent of patients (100% at DL3) experienced freedom from local tumor progression. In 75% of patients who eventually experienced progression, metastases developed without local progression. RR levels did not seem to predict outcome. In 4 patients with available data, dynamic contrast-enhanced magnetic resonance imaging may predict early response or resistance to therapy. Conclusion: The combination of triapine at 72 mg/m{sup 2} 3 times weekly every other week and standard RT is tolerable with interesting activity in patients with LAPCA.« less

Potential for differentiation of pseudoprogression from true tumor progression with dynamic susceptibility-weighted contrast-enhanced magnetic resonance imaging using ferumoxytol versus gadoteridol: A pilot study

PubMed Central

Gahramanov, Seymur; Raslan, Ahmed; Muldoon, Leslie L.; Hamilton, Bronwyn E.; Rooney, William D.; Varallyay, Csanad G.; Njus, Jeffrey M.; Haluska, Marianne; Neuwelt, Edward A.

2010-01-01

Purpose We evaluated dynamic susceptibility-weighted contrast-enhanced magnetic resonance imaging (DSC-MRI) using gadoteridol in comparison to the iron oxide nanoparticle blood pool agent, ferumoxytol in patients with glioblastoma multiforme (GBM) who received standard radiochemotherapy (RCT). Methods and Materials Fourteen patients with GBM received standard RCT and underwent 19 MRI sessions that included DSC-MRI acquisitions with gadoteridol on day 1 and ferumoxytol on day 2. Relative cerebral blood volume (rCBV) values were calculated from DSC data obtained from each contrast agent. T1-weighted acquisition post-gadoteridol administration was used to identify enhancing regions. Results In 7 MRI sessions of clinically presumptive active tumor, gadoteridol-DSC showed low rCBV in 3 and high rCBV in 4, while ferumoxytol-DSC showed high rCBV in all 7 sessions (p=0.002). After RCT, 7 MRI sessions showed increased gadoteridol contrast enhancement on T1-weighted scans coupled with low rCBV without significant differences between contrast agents (p=0.9). Based on post-gadoteridol T1-weighted scans, DSC-MRI, and clinical presentation four patterns of response to RCT were observed: 1) regression, 2) pseudoprogression, 3) true progression, and 4) mixed response. Conclusion We conclude that DSC-MRI with a blood-pool agent such as ferumoxytol may provide a better monitor of tumor rCBV than DSC-MRI with gadoteridol. Lesions demonstrating increased enhancement on T1-weighted MRI coupled with low ferumoxytol rCBV, are likely exhibiting pseudoprogression, while high rCBV with ferumoxytol is a better marker than gadoteridol for determining active tumor. These interesting pilot observations suggest that ferumoxytol may differentiate tumor progression from pseudoprogression, and warrant further investigation. PMID:20395065

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jalali, Rakesh, E-mail: rjalali@tmc.gov.i; Raut, Nirmal; Arora, Brijesh

Purpose: To present outcome data in a prospective study of radiotherapy (RT) with concurrent and adjuvant temozolomide (TMZ) in children with diffuse intrinsic pontine gliomas (DIPGs). Methods and Materials: Pediatric patients with newly diagnosed DIPGs were prospectively treated with focal RT to a dose of 54 Gy in 30 fractions along with concurrent daily TMZ (75 mg/m{sup 2}, Days 1-42). Four weeks after completing the initial RT-TMZ schedule, adjuvant TMZ (200 mg/m{sup 2}, Days 1-5) was given every 28 days to a maximum of 12 cycles. Response was evaluated clinically and radiologically with magnetic resonance imaging and positron emission tomographymore » scans. Results: Between March 2005 and November 2006, 20 children (mean age, 8.3 years) were accrued. Eighteen patients have died from disease progression, one patient is alive with progressive disease, and one patient is alive with stable disease. Median overall survival and progression-free survival were 9.15 months and 6.9 months, respectively. Grade III/IV toxicity during the concurrent RT-TMZ phase included thrombocytopenia in 3 patients, leucopenia in 2, and vomiting in 7. Transient Grade II skin toxicity developed in the irradiated fields in 18 patients. During the adjuvant TMZ phase, Grade III/IV leucopenia developed in 2 patients and Grade IV thrombocytopenia in 1 patient. Patients with magnetic resonance imaging diagnosis of a high-grade tumor had worse survival than those with a low-grade tumor (p = 0.001). Patients with neurologic improvement after RT-TMZ had significantly better survival than those who did not (p = 0.048). Conclusions: TMZ with RT has not yielded any improvement in the outcome of DIPG compared with RT alone. Further clinical trials should explore novel treatment modalities.« less

Scanning microwave microscopy technique for nanoscale characterization of magnetic materials

NASA Astrophysics Data System (ADS)

Joseph, C. H.; Sardi, G. M.; Tuca, S. S.; Gramse, G.; Lucibello, A.; Proietti, E.; Kienberger, F.; Marcelli, R.

2016-12-01

In this work, microwave characterization of magnetic materials using the scanning microwave microscopy (SMM) technique is presented. The capabilities of the SMM are employed for analyzing and imaging local magnetic properties of the materials under test at the nanoscale. The analyses are performed by acquiring both amplitude and phase of the reflected microwave signal. The changes in the reflection coefficient S11 are related to the local properties of the material under investigation, and the changes in its magnetic properties have been studied as a function of an external DC magnetic bias. Yttrium iron garnet (YIG) films deposited by RF sputtering and grown by liquid phase epitaxial (LPE) on gadolinium gallium garnet (GGG) substrates and permalloy samples have been characterized. An equivalent electromagnetic transmission line model is discussed for the quantitative analysis of the local magnetic properties. We also observed the hysteretic behavior of the reflection coefficient S11 with an external bias field. The imaging and spectroscopy analysis on the experimental results are evidently indicating the possibilities of measuring local changes in the intrinsic magnetic properties on the surface of the material.

Magnetic materials selection for static inverter and converter transformers

NASA Technical Reports Server (NTRS)

Mclyman, W. T.

1973-01-01

A program to study magnetic materials is described for use in spacecraft transformers used in static inverters, converters, and transformer-rectifier supplies. Different magnetic alloys best suited for high-frequency and high-efficiency applications were comparatively investigated together with an investigation of each alloy's inherent characteristics. The materials evaluated were the magnetic alloys: (1) 50% Ni, 50% Fe; (2) 79% Ni, 17% Fe, 4% Mo; (3) 48% Ni, 52% Fe; (4) 78% Ni, 17% Fe, 5% Mo; and (5) 3% Si, 97% Fe. Investigations led to the design of a transformer with a very low residual flux. Tests were performed to determine the dc and ac magnetic properties at 2400 Hz using square-wave excitation. These tests were performed on uncut cores, which were then cut for comparison of the gapped and ungapped magnetic properties. When the data of many transformers in many configurations were compiled the optimum transformer was found to be that with the lowest residual flux and a small amount of air gap in the magnetic material. The data obtained from these tests are described, and the potential uses for the materials are discussed.

Micro-position sensor using faraday effect

DOEpatents

McElfresh, Michael [Livermore, CA; Lucas, Matthew [Pittsburgh, PA; Silveira, Joseph P [Tracy, CA; Groves, Scott E [Brentwood, CA

2007-02-27

A micro-position sensor and sensing system using the Faraday Effect. The sensor uses a permanent magnet to provide a magnetic field, and a magneto-optic material positioned in the magnetic field for rotating the plane of polarization of polarized light transmitted through the magneto-optic material. The magnet is independently movable relative to the magneto-optic material so as to rotate the plane of polarization of the polarized light as a function of the relative position of the magnet. In this manner, the position of the magnet relative to the magneto-optic material may be determined from the rotated polarized light. The sensing system also includes a light source, such as a laser or LED, for producing polarized light, and an optical fiber which is connected to the light source and to the magneto-optic material at a sensing end of the optical fiber. Processing electronics, such as a polarimeter, are also provided for determining the Faraday rotation of the plane of polarization of the back-reflected polarized light to determine the position of the magnet relative to the sensing end of the optical fiber.

Magnetic materials and devices for the 21st century: stronger, lighter, and more energy efficient.

PubMed

Gutfleisch, Oliver; Willard, Matthew A; Brück, Ekkes; Chen, Christina H; Sankar, S G; Liu, J Ping

2011-02-15

A new energy paradigm, consisting of greater reliance on renewable energy sources and increased concern for energy efficiency in the total energy lifecycle, has accelerated research into energy-related technologies. Due to their ubiquity, magnetic materials play an important role in improving the efficiency and performance of devices in electric power generation, conditioning, conversion, transportation, and other energy-use sectors of the economy. This review focuses on the state-of-the-art hard and soft magnets and magnetocaloric materials, with an emphasis on their optimization for energy applications. Specifically, the impact of hard magnets on electric motor and transportation technologies, of soft magnetic materials on electricity generation and conversion technologies, and of magnetocaloric materials for refrigeration technologies, are discussed. The synthesis, characterization, and property evaluation of the materials, with an emphasis on structure-property relationships, are discussed in the context of their respective markets, as well as their potential impact on energy efficiency. Finally, considering future bottlenecks in raw materials, options for the recycling of rare-earth intermetallics for hard magnets will be discussed. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Toward Magnetorheological Finishing of Magnetic Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shafrir, S.N.; Lambropoulos, J.C.; Jacobs, S.D.

2007-10-24

Magnetorheological finishing (MRF) is a precision finishing process traditionally limited to processing only nonmagnetic materials, e.g., optical glasses, ceramics, polymers, and metals. Here we demonstrate that MRF can be used for material removal from magnetic material surfaces. Our approach is to place an MRF spot on machined surfaces of magnetic WC-Co materials. The resulting surface roughness is comparable to that produced on nonmagnetic materials. This spotting technique may be used to evaluate the depth of subsurface damage, or deformed layer, induced by earlier manufacturing steps, such as grinding and lapping.

Synthesizing and Playing with Magnetic Nanoparticles: A Comprehensive Approach to Amazing Magnetic Materials

ERIC Educational Resources Information Center

Dalverny, Anne-Laure; Leyral, Géraldine; Rouessac, Florence; Bernaud, Laurent; Filhol, Jean-Sébastien

2018-01-01

Magnetic iron oxide nanoparticles were synthesized and stabilized using ammonium cations or poly(vinyl alcohol) to produce amazing materials such as safer aqueous ferrofluids, ferrogels, ferromagnetic inks, plastics, and nanopowders illustrating how versatile materials can be produced just by simple modifications. The synthesis is fast, reliable,…

Perspectives on Permanent Magnetic Materials for Energy Conversion and Power Generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, LH; Jimenez-Villacorta, F

2012-07-18

Permanent magnet development has historically been driven by the need to supply larger magnetic energy in ever smaller volumes for incorporation in an enormous variety of applications that include consumer products, transportation components, military hardware, and clean energy technologies such as wind turbine generators and hybrid vehicle regenerative motors. Since the 1960s, the so-called rare-earth "supermagnets," composed of iron, cobalt, and rare-earth elements such as Nd, Pr, and Sm, have accounted for the majority of global sales of high-energy-product permanent magnets for advanced applications. In rare-earth magnets, the transition-metal components provide high magnetization, and the rare-earth components contribute a verymore » large magnetocrystalline anisotropy that donates high resistance to demagnetization. However, at the end of 2009, geopolitical influences created a worldwide strategic shortage of rare-earth elements that may be addressed, among other actions, through the development of rare-earth-free magnetic materials harnessing sources of magnetic anisotropy other than that provided by the rare-earth components. Materials engineering at the micron scale, nanoscale, and Angstrom scales, accompanied by improvements in the understanding and characterization of nanoscale magnetic phenomena, is anticipated to result in new types of permanent magnetic materials with superior performance. DOI: 10.1007/s11661-012-1278-2 (C) The Minerals, Metals & Materials Society and ASM International 2012« less

Permanent Magnet Ecr Plasma Source With Magnetic Field Optimization

DOEpatents

Doughty, Frank C.; Spencer, John E.

2000-12-19

In a plasma-producing device, an optimized magnet field for electron cyclotron resonance plasma generation is provided by a shaped pole piece. The shaped pole piece adjusts spacing between the magnet and the resonance zone, creates a convex or concave resonance zone, and decreases stray fields between the resonance zone and the workpiece. For a cylindrical permanent magnet, the pole piece includes a disk adjacent the magnet together with an annular cylindrical sidewall structure axially aligned with the magnet and extending from the base around the permanent magnet. The pole piece directs magnetic field lines into the resonance zone, moving the resonance zone further from the face of the magnet. Additional permanent magnets or magnet arrays may be utilized to control field contours on a local scale. Rather than a permeable material, the sidewall structure may be composed of an annular cylindrical magnetic material having a polarity opposite that of the permanent magnet, creating convex regions in the resonance zone. An annular disk-shaped recurve section at the end of the sidewall structure forms magnetic mirrors keeping the plasma off the pole piece. A recurve section composed of magnetic material having a radial polarity forms convex regions and/or magnetic mirrors within the resonance zone.

Eddy current characterization of magnetic treatment of materials

NASA Technical Reports Server (NTRS)

Chern, E. James

1992-01-01

Eddy current impedance measuring methods have been applied to study the effect that magnetically treated materials have on service life extension. Eddy current impedance measurements have been performed on Nickel 200 specimens that have been subjected to many mechanical and magnetic engineering processes: annealing, applied strain, magnetic field, shot peening, and magnetic field after peening. Experimental results have demonstrated a functional relationship between coil impedance, resistance and reactance, and specimens subjected to various engineering processes. It has shown that magnetic treatment does induce changes in a material's electromagnetic properties and does exhibit evidence of stress relief. However, further fundamental studies are necessary for a thorough understanding of the exact mechanism of the magnetic-field processing effect on machine tool service life.

Replacing critical rare earth materials in high energy density magnets

NASA Astrophysics Data System (ADS)

McCallum, R. William

2012-02-01

High energy density permanent magnets are crucial to the design of internal permanent magnet motors (IPM) for hybride and electric vehicles and direct drive wind generators. Current motor designs use rare earth permanent magnets which easily meet the performance goals, however, the rising concerns over cost and foreign control of the current supply of rare earth resources has motivated a search for non-rare earth based permanent magnets alloys with performance metrics which allow the design of permanent magnet motors and generators without rare earth magnets. This talk will discuss the state of non-rare-earth permanent magnets and efforts to both improve the current materials and find new materials. These efforts combine first principles calculations and meso-scale magnetic modeling with advance characterization and synthesis techniques in order to advance the state of the art in non rare earth permanent magnets. The use of genetic algorithms in first principle structural calculations, combinatorial synthesis in the experimental search for materials, atom probe microscopy to characterize grain boundaries on the atomic level, and other state of the art techniques will be discussed. In addition the possibility of replacing critical rare earth elements with the most abundant rare earth Ce will be discussed.

Perspectives on Permanent Magnetic Materials for Energy Conversion and Power Generation

NASA Astrophysics Data System (ADS)

Lewis, Laura H.; Jiménez-Villacorta, Félix

2013-01-01

Permanent magnet development has historically been driven by the need to supply larger magnetic energy in ever smaller volumes for incorporation in an enormous variety of applications that include consumer products, transportation components, military hardware, and clean energy technologies such as wind turbine generators and hybrid vehicle regenerative motors. Since the 1960s, the so-called rare-earth "supermagnets," composed of iron, cobalt, and rare-earth elements such as Nd, Pr, and Sm, have accounted for the majority of global sales of high-energy-product permanent magnets for advanced applications. In rare-earth magnets, the transition-metal components provide high magnetization, and the rare-earth components contribute a very large magnetocrystalline anisotropy that donates high resistance to demagnetization. However, at the end of 2009, geopolitical influences created a worldwide strategic shortage of rare-earth elements that may be addressed, among other actions, through the development of rare-earth-free magnetic materials harnessing sources of magnetic anisotropy other than that provided by the rare-earth components. Materials engineering at the micron scale, nanoscale, and Angstrom scales, accompanied by improvements in the understanding and characterization of nanoscale magnetic phenomena, is anticipated to result in new types of permanent magnetic materials with superior performance.

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

NASA Astrophysics Data System (ADS)

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

2013-04-01

A detailed field study on small test site of agricultural land situated in loess region in Southern Moravia (Czech Republic), followed by laboratory analyses, has been carried out in order to test the applicability of magnetic methods in soil erosion estimation. The approach is based on the well-established differentiation in magnetic signature of topsoil from subsoil horizons as a result of "in situ" formation of strongly magnetic iron oxides e.g. (Maher 1986). Introducing a simple tillage homogenization model for predicting magnetic signal after uniform mixing of soil material as a result of tillage and subsequent erosion, Royall (2001) showed that magnetic susceptibility and its frequency dependence can be used to estimate soil loss. Haplic Chernozem is an original dominant soil unit in the wider area, nowadays progressively transformed into different soil units along with intensive soil erosion. The site was characterized by a flat upper part while the middle part, formed by a substantive side valley, is steeper (up to 15°). The side valley represented a major line of concentrated runoff emptying into a colluvial fan (Zadorova et al., 2011; Jaksik et al., 2011). Field measurements of magnetic susceptibility were carried out on regular grid, resulting in 101 data points. Bulk soil material for laboratory investigation was gathered from all grid points. Mass specific magnetic susceptibility χ and its frequency dependence kFD was used to estimate the significance of SP ferrimagnetic particles of pedogenic origin. Thermomagnetic analyses, hysteresis measurement and SEM were used in order to determine dominant ferrimagnetic carriers in top-soil and sub-soil layers. Strong correlation was found between the volume magnetic susceptibility (field measurement) and mass specific magnetic susceptibility measured in the laboratory (R2 = 0.80). At the same time, no correlations were found between the values of kFD and mass specific susceptibility. Values of organic carbon content, pHKCl and magnetic susceptibly are spatially distributed depending on terrain position. Higher values of magnetic susceptibly and organic carbon content were measured at the flat upper part (where the original top horizon remained). The lowest values of organic carbon content and magnetic susceptibly were obtained on the steep valley sides. Here the original topsoil was eroded and mixed by tillage with the soil substrate (loess). Regression analysis showed positive correlation between the organic carbon content and volume magnetic susceptibility (R2= 0.89). Vertical distribution of magnetic susceptibility along the selected transect was measured using SM400 soil kappameter (Petrovský et al., 2004). Differences between susceptibility values in undisturbed soil profiles and magnetic signal after uniform mixing of soil material as a result of tillage and erosion are fundamental for estimation of soil loss in studied test field. Acknowledgement: This study was supported by NAZV Agency of the Ministry of Agriculture of the Czech Republic through grant No QJ1230319. References. Jakšík, O., Kodešová, R., Stehlíková, I., Kapička, A. (2011). Mapování změn půdních vlastností v důsledku eroze. In: Sb. Konf. Hydrologie malého povodí 2011, (M. Šír, M. Tesař, Eds.), 183-188. Maher, B. (1986). Characterization of soils by mineral magnetic measurements. Phys Earth Planet. Int. 42, 76-92. Petrovský, E., Hůlka, Z., Kapička, A. (2004). A new tool for in situ measurements of the vertical distribution of magnetic susceptibility in soils as basis for mapping deposited dust. Environ. Tech., 25, 1021-1029. Royall, D. (2001). Use of mineral magnetic measurements to investigate soil erosion and sediment delivery in a small agricultural catchment in limestone terrain. Catena 46, 15-34. Zadorova, T., Penizek, V., Sefrna, L., Rohoskova, M., Boruvka, L. (2011). Spatial delineation of organic carbon-rich Colluvial soils in Chernozem regions by Terrain analysis and fuzzy classification, Catena, 85, 22-33

A mechanical characterisation on multiple timescales of electroconductive magnetorheological elastomers

NASA Astrophysics Data System (ADS)

Schümann, M.; Morich, J.; Kaufhold, T.; Böhm, V.; Zimmermann, K.; Odenbach, S.

2018-05-01

Magnetorheological elastomers are a type of smart hybrid material which combines elastic properties of a soft elastomer matrix with magnetic properties of magnetic micro particles. This leads to a material with magnetically controllable mechanical properties of which the magnetorheological effect is the best known. The addition of electroconductive particles to the polymer mix adds electrical properties to the material behaviour. The resulting electrical resistance of the sample can be manipulated by external magnetic fields and mechanical loads. This results in a distinct interplay of mechanical, electrical and magnetic effects with a highly complex time behaviour. In this paper a mechanical characterisation on multiple time scales was conducted to get an insight on the short and long-term electrical and mechanical behaviour of this novel material. The results show a complex resistivity behaviour on several timescales, sensitive to magnetic fields and strain velocity. The observed material exhibits fatigue and relaxation behaviour, whereas the magnetorheological effect appears not to interfere with the piezoresistive properties.

Power losses of soft magnetic composite materials under two-dimensional excitation

NASA Astrophysics Data System (ADS)

Zhu, J. G.; Zhong, J. J.; Ramsden, V. S.; Guo, Y. G.

1999-04-01

Soft magnetic composite materials produced by powder metallurgy techniques can be very useful for construction of low cost small motors. However, the rotational core losses and the corresponding B-H relationships of soft magnetic composite materials with two-dimensional rotating fluxes have neither been supplied by the manufacturers nor reported in the literature. This article reports the core loss measurement of a soft magnetic composite material, SOMALOY™ 500, Höganäs AB, Sweden, under two-dimensional excitations. The principle of measurement, testing system, and power loss calculation are presented. The results are analyzed and discussed.

Advanced transition metal phosphide materials from single-source molecular precursors

NASA Astrophysics Data System (ADS)

Colson, Adam Caleb

In this thesis, the feasibility of employing organometallic single-source precursors in the preparation of advanced transition metal pnictide materials such as colloidal nanoparticles and films has been investigated. In particular, the ternary FeMnP phase was targeted as a model for preparing advanced heterobimetallic phosphide materials, and the iron-rich Fe3P phase was targeted due to its favorable ferromagnetic properties as well as the fact that the preparation of advanced Fe3P materials has been elusive by commonly used methods. Progress towards the synthesis of advanced Fe2--xMn xP nanomaterials and films was facilitated by the synthesis of the novel heterobimetallic complexes FeMn(CO)8(mu-PR1R 2) (R1 = H, R2 = H or R1 = H, R2 = Ph), which contain the relatively rare mu-PH2 and mu-PPhH functionalities. Iron rich Fe2--xMnxP nanoparticles were obtained by thermal decomposition of FeMn(CO)8(mu-PH 2) using solution-based synthetic methods, and empirical evidence suggested that oleic acid was responsible for manganese depletion. Films containing Fe, Mn, and P with the desired stoichiometric ratio of 1:1:1 were prepared using FeMn(CO)8(mu-PH2) in a simple low-pressure metal-organic chemical vapor deposition (MOCVD) apparatus. Although the elemental composition of the precursor was conserved in the deposited film material, spectroscopic evidence indicated that the films were not composed of pure-phase FeMnP, but were actually mixtures of crystalline FeMnP and amorphous FeP and Mn xOy. A new method for the preparation of phase-pure ferromagnetic Fe 3P films on quartz substrates has also been developed. This approach involved the thermal decomposition of the single-source precursors H 2Fe3(CO)9PR (R = tBu or Ph) at 400 °C. The films were deposited using a simple home-built MOCVD apparatus and were characterized using a variety of analytical methods. The films exhibited excellent phase purity, as evidenced by X-ray diffraction, X-ray photoelectron spectroscopy, and field-dependent magnetization measurements, the results of which were all in good agreement with measurements obtained from bulk Fe3P. As-deposited Fe3P films were found to be amorphous, and little or no magnetic hysteresis was observed in plots of magnetization versus applied field. Annealing the Fe3P films at 550 °C resulted in improved crystallinity as well as the observation of magnetic hysteresis.

Thick film magnetic nanoparticulate composites and method of manufacture thereof

NASA Technical Reports Server (NTRS)

Ge, Shihui (Inventor); Yan, Dajing (Inventor); Xiao, Danny T. (Inventor); Ma, Xinqing (Inventor); Zhang, Yide (Inventor); Zhang, Zongtao (Inventor)

2009-01-01

Thick film magnetic/insulating nanocomposite materials, with significantly reduced core loss, and their manufacture are described. The insulator coated magnetic nanocomposite comprises one or more magnetic components, and an insulating component. The magnetic component comprises nanometer scale particles (about 1 to about 100 nanometers) coated by a thin-layered insulating phase. While the intergrain interaction between the immediate neighboring magnetic nanoparticles separated by the insulating phase provides the desired soft magnetic properties, the insulating material provides high resistivity, which reduces eddy current loss.

A comparison between progressive extension method (PEM) and iterative method (IM) for magnetic field extrapolations in the solar atmosphere

NASA Technical Reports Server (NTRS)

Wu, S. T.; Sun, M. T.; Sakurai, Takashi

1990-01-01

This paper presents a comparison between two numerical methods for the extrapolation of nonlinear force-free magnetic fields, viz the Iterative Method (IM) and the Progressive Extension Method (PEM). The advantages and disadvantages of these two methods are summarized, and the accuracy and numerical instability are discussed. On the basis of this investigation, it is claimed that the two methods do resemble each other qualitatively.

Modeling the Magnetic and Thermal Structure of Active Regions: 1st Year 1st Semi-Annual Progress Report

NASA Technical Reports Server (NTRS)

Mikic, Zoran

2003-01-01

This report covers technical progress during the first six months of the first year of NASA SR&T contract "Modeling the Magnetic and Thermal Structure of Active Regions", NASW-03008, between NASA and Science Applications International Corporation, and covers the period January 14, 2003 to July 13, 2003. Under this contract SAIC has conducted research into theoretical modeling of the properties of active regions using the MHD model.

Advances in nonlinear optical materials and devices

NASA Technical Reports Server (NTRS)

Byer, Robert L.

1991-01-01

The recent progress in the application of nonlinear techniques to extend the frequency of laser sources has come from the joint progress in laser sources and in nonlinear materials. A brief summary of the progress in diode pumped solid state lasers is followed by an overview of progress in nonlinear frequency extension by harmonic generation and parametric processes. Improved nonlinear materials including bulk crystals, quasiphasematched interactions, guided wave devices, and quantum well intersubband studies are discussed with the idea of identifying areas of future progress in nonlinear materials and devices.

Physics and application of persistent spin helix state in semiconductor heterostructures

NASA Astrophysics Data System (ADS)

Kohda, Makoto; Salis, Gian

2017-07-01

In order to utilize the spin degree of freedom in semiconductors, control of spin states and transfer of the spin information are fundamental requirements for future spintronic devices and quantum computing. Spin orbit (SO) interaction generates an effective magnetic field for moving electrons and enables spin generation, spin manipulation and spin detection without using external magnetic field and magnetic materials. However, spin relaxation also takes place due to a momentum dependent SO-induced effective magnetic field. As a result, SO interaction is considered to be a double-edged sword facilitating spin control but preventing spin transport over long distances. The persistent spin helix (PSH) state solves this problem since uniaxial alignment of the SO field with SU(2) symmetry enables the suppression of spin relaxation while spin precession can still be controlled. Consequently, understanding the PSH becomes an important step towards future spintronic technologies for classical and quantum applications. Here, we review recent progress of PSH in semiconductor heterostructures and its device application. Fundamental physics of SO interaction and the conditions of a PSH state in semiconductor heterostructures are discussed. We introduce experimental techniques to observe a PSH and explain both optical and electrical measurements for detecting a long spin relaxation time and the formation of a helical spin texture. After emphasizing the bulk Dresselhaus SO coefficient γ, the application of PSH states for spin transistors and logic circuits are discussed.

Magnetic and structural properties of yellow europium oxide compound and Eu(OH){sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Dongwook, E-mail: dongwookleedl324@gmail.com; Seo, Jiwon, E-mail: jiwonseo@yonsei.ac.kr; Valladares, Luis de los Santos

A new material based on a yellow europium oxide compound was prepared from europium oxide in a high vacuum environment. The structural and magnetic properties of the material were investigated. Owing to the absence of a crystal structure, the material exhibited a disordered magnetic behavior. In a reaction with deionized (DI) water without applied heat, the compound assumed a white color as soon as the DI water reached the powder, and the structure became polycrystalline Eu(OH){sub 3}. The magnetic properties, such as the thermal hysteresis, disappeared after the reaction with DI water, and the magnetic susceptibility of the yellow oxidemore » compound weakened. The magnetic properties of Eu(OH){sub 3} were also examined. Although Eu{sup 3+} is present in Eu(OH){sub 3}, a high magnetic moment due to the crystal field effect was observed. - Graphical abstract: (top left) Optical image of the yellow europium oxide compound. (top right) Optical image of the product of DI water and yellow europium oxide. (bottom) Magnetization curves as a function of temperature measured in various magnetic field. - Highlights: • We prepared a new material based on a yellow europium oxide compound from europium oxide. • We characterized the magnetic properties of the material which exhibits a disordered magnetic behavior such as thermal hysteresis. • The compound turned white (Eu(OH){sub 3}) as soon as the DI water reached the powder. • The thermal hysteresis disappeared after the reaction with DI water and the magnetic susceptibility of the yellow oxide compound weakened.« less

Multiparameter magnetic inspection system with magnetic field control and plural magnetic transducers

DOEpatents

Jiles, D.C.

1991-04-16

A multiparameter magnetic inspection system is disclosed for providing an efficient and economical way to derive a plurality of independent measurements regarding magnetic properties of the magnetic material under investigation. The plurality of transducers for a plurality of different types of measurements operatively connected to the specimen. The transducers are in turn connected to analytical circuits for converting transducer signals to meaningful measurement signals of the magnetic properties of the specimen. The measurement signals are processed and can be simultaneously communicated to a control component. The measurement signals can also be selectively plotted against one another. The control component operates the functioning of the analytical circuits and operates and controls components to impose magnetic fields of desired characteristics upon the specimen. The system therefore allows contemporaneous or simultaneous derivation of the plurality of different independent magnetic properties of the material which can then be processed to derive characteristics of the material. 1 figure.

Multiparameter magnetic inspection system with magnetic field control and plural magnetic transducers

DOEpatents

Jiles, David C.

1991-04-16

A multiparameter magnetic inspection system for providing an efficient and economical way to derive a plurality of independent measurements regarding magnetic properties of the magnetic material under investigation. The plurality of transducers for a plurality of different types of measurements operatively connected to the specimen. The transducers are in turn connected to analytical circuits for converting transducer signals to meaningful measurement signals of the magnetic properties of the specimen. The measurement signals are processed and can be simultaneously communicated to a control component. The measurement signals can also be selectively plotted against one another. The control component operates the functioning of the analytical circuits and operates and controls components to impose magnetic fields of desired characteristics upon the specimen. The system therefore allows contemporaneous or simultaneous derivation of the plurality of different independent magnetic properties of the material which can then be processed to derive characteristics of the material.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsukada, K., E-mail: tsukada@cc.okayama-u.ac.jp; Kusaka, T.; Saari, M. M.

2014-05-07

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

Perspectives for high-performance permanent magnets: applications, coercivity, and new materials

NASA Astrophysics Data System (ADS)

Hirosawa, Satoshi; Nishino, Masamichi; Miyashita, Seiji

2017-03-01

High-performance permanent magnets are indispensable in the production of high-efficiency motors and generators and ultimately for sustaining the green earth. The central issue of modern permanent magnetism is to realize high coercivity near and above room temperature on marginally hard magnetic materials without relying upon the critical elements such as heavy rare earths by means of nanostructure engineering. Recent investigations based on advanced nanostructure analysis and large-scale first principles calculations have led to significant paradigm shifts in the understandings of coercivity mechanism in Nd-Fe-B permanent magnets, which includes the discovery of the ferromagnetism of the thin (2 nm) intergranular phase surrounding the Nd2Fe14B grains, the occurrence of negative (in-plane) magnetocrystalline anisotropy of Nd ions and some Fe atoms at the interface which degrades coercivity, and visualization of the stochastic behaviors of magnetization in the magnetization reversal process at high temperatures. A major change may occur also in the motor topologies, which is currently overwhelmed by the magnetic flux weakening interior permanent magnet motor type, to other types with variable flux permanent magnet type in some applications to open up a niche for new permanent magnet materials. Keynote talk at 8th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN2016), 8-12 November 2016, Ha Long City, Vietnam.

Investigation of Anisotropic Bonded Magnets in Permanent Magnet Machine Applications

NASA Astrophysics Data System (ADS)

Khazdozian, H. A.; McCall, S. K.; Kramer, M. J.; Paranthaman, M. P.; Nlebedim, I. C.

Rare earth elements (REE) provide the high energy product necessary for permanent magnets, such as sintered Nd2Fe14B, in many applications like wind energy generators. However, REEs are considered critical materials due to risk in their supply. To reduce the use of critical materials in permanent magnet machines, the performance of anisotropic bonded NdFeB magnets, aligned under varying magnetic field strength, was simulated using 3D finite element analysis in a 3MW direct-drive permanent magnet generator (DDPMG), with sintered N42 magnets used as a baseline for comparison. For direct substitution of the anisotropic bonded magnets, approximately 85% of the efficiency of the baseline model was achieved, irrespective of the alignment field. The torque and power generation of the DDPMG was not found to vary significantly with increase in the alignment field. Finally, design changes were studied to allow for the achievement of rated torque and power with the use of anisotropic bonded magnets, demonstrating the potential for reduction of critical materials in permanent magnets for renewable energy applications. This work was supported by the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office.

Impact of the interaction of material production and mechanical processing on the magnetic properties of non-oriented electrical steel

NASA Astrophysics Data System (ADS)

Leuning, Nora; Steentjes, Simon; Stöcker, Anett; Kawalla, Rudolf; Wei, Xuefei; Dierdorf, Jens; Hirt, Gerhard; Roggenbuck, Stefan; Korte-Kerzel, Sandra; Weiss, Hannes A.; Volk, Wolfram; Hameyer, Kay

2018-04-01

Thin laminations of non-grain oriented (NO) electrical steels form the magnetic core of rotating electrical machines. The magnetic properties of these laminations are therefore key elements for the efficiency of electric drives and need to be fully utilized. Ideally, high magnetization and low losses are realized over the entire polarization and frequency spectrum at reasonable production and processing costs. However, such an ideal material does not exist and thus, achievable magnetic properties need to be deduced from the respective application requirements. Parameters of the electrical steel such as lamination thickness, microstructure and texture affect the magnetic properties as well as their polarization and frequency dependence. These structural features represent possibilities to actively alter the magnetic properties, e.g., magnetization curve, magnetic loss or frequency dependence. This paper studies the influence of production and processing on the resulting magnetic properties of a 2.4 wt% Si electrical steel. Aim is to close the gap between production influence on the material properties and its resulting effect on the magnetization curves and losses at different frequencies with a strong focus on occurring interdependencies between production and mechanical processing. The material production is realized on an experimental processing route that comprises the steps of hot rolling, cold rolling, annealing and punching.

Fabrication and Evaluation of Superconducting and Semiconducting Materials

DTIC Science & Technology

1993-09-01

Laboratory Material Physics Branch by conducting investigations into the properties of superconducting , magnetic , and other solid state materials. Studies...Physics Branch in conducting research into applied problems such as the design of magnetic shielding and superconducting quantum interference device...SQUID) magnetometry detection of magnetic anomalies. SFA provided research assistance in the areas of bulk ceramic sample preparation. conversion

Ab initio study of (Fe, Ni) doped GaAs: Magnetic, electronic properties and Faraday rotation

NASA Astrophysics Data System (ADS)

Sbai, Y.; Ait Raiss, A.; Bahmad, L.; Benyoussef, A.

2017-06-01

The interesting diluted magnetic semiconductor (DMS), Gallium Arsenide (GaAs), was doped with the transition metals magnetic impurities: iron (Fe) and Nickel (Ni), in one hand to study the magnetic and magneto-optical properties of the material Ga(Fe, Ni) As, in the other hand to investigate the effect of the doping on the properties of this material, the calculations were performed within the spin polarized density functional theory (DFT) and generalized gradient approximation (GGA) with AKAI KKR-CPA method, the density of states (DOS) for different doping concentrations were calculated, giving the electronical properties, as well as the magnetic state and magnetic states energy, also the effect of these magnetic impurities on the Faraday rotation as magneto-optical property. Furthermore, we found the stable magnetic state for our doped material GaAs.

Electromagnetic valve for controlling the flow of molten, magnetic material

DOEpatents

Richter, T.

1998-06-16

An electromagnetic valve for controlling the flow of molten, magnetic material is provided, which comprises an induction coil for generating a magnetic field in response to an applied alternating electrical current, a housing, and a refractory composite nozzle. The nozzle is comprised of an inner sleeve composed of an erosion resistant refractory material (e.g., a zirconia ceramic) through which molten, magnetic metal flows, a refractory outer shell, and an intermediate compressible refractory material, e.g., unset, high alumina, thermosetting mortar. The compressible refractory material is sandwiched between the inner sleeve and outer shell, and absorbs differential expansion stresses that develop within the nozzle due to extreme thermal gradients. The sandwiched layer of compressible refractory material prevents destructive cracks from developing in the refractory outer shell. 5 figs.

Electromagnetic valve for controlling the flow of molten, magnetic material

DOEpatents

Richter, Tomas

1998-01-01

An electromagnetic valve for controlling the flow of molten, magnetic material is provided, which comprises an induction coil for generating a magnetic field in response to an applied alternating electrical current, a housing, and a refractory composite nozzle. The nozzle is comprised of an inner sleeve composed of an erosion resistant refractory material (e.g., a zirconia ceramic) through which molten, magnetic metal flows, a refractory outer shell, and an intermediate compressible refractory material, e.g., unset, high alumina, thermosetting mortar. The compressible refractory material is sandwiched between the inner sleeve and outer shell, and absorbs differential expansion stresses that develop within the nozzle due to extreme thermal gradients. The sandwiched layer of compressible refractory material prevents destructive cracks from developing in the refractory outer shell.

3D-Printed Permanent Magnets Outperform Conventional Versions, Conserve Rare Materials

ScienceCinema

Paranthaman, Parans

2018-06-13

Researchers at the Department of Energy’s Oak Ridge National Laboratory have demonstrated that permanent magnets produced by additive manufacturing can outperform bonded magnets made using traditional techniques while conserving critical materials. The project is part of DOE’s Critical Materials Institute (CMI), which seeks ways to eliminate and reduce reliance on rare earth metals and other materials critical to the success of clean energy technologies.

The relation between magnetic and material arms in models for spiral galaxies

NASA Astrophysics Data System (ADS)

Moss, D.; Beck, R.; Sokoloff, D.; Stepanov, R.; Krause, M.; Arshakian, T. G.

2013-08-01

Context. Observations of polarized radio emission show that large-scale (regular) magnetic fields in spiral galaxies are not fully axisymmetric, but generally stronger in interarm regions. In some nearby galaxies such as NGC 6946 they are organized in narrow magnetic arms situated between the material spiral arms. Aims: The phenomenon of magnetic arms and their relation to the optical spiral arms (the material arms) calls for an explanation in the framework of galactic dynamo theory. Several possibilities have been suggested but are not completely satisfactory; here we attempt a consistent investigation. Methods: We use a 2D mean-field dynamo model in the no-z approximation and add injections of small-scale magnetic field, taken to result from supernova explosions, to represent the effects of dynamo action on smaller scales. This injection of small scale field is situated along the spiral arms, where star-formation mostly occurs. Results: A straightforward explanation of magnetic arms as a result of modulation of the dynamo mechanism by material arms struggles to produce pronounced magnetic arms, at least with realistic parameters, without introducing new effects such as a time lag between Coriolis force and α-effect. In contrast, by taking into account explicitly the small-scale magnetic field that is injected into the arms by the action of the star forming regions that are concentrated there, we can obtain dynamo models with magnetic structures of various forms that can be compared with magnetic arms. These are rather variable entities and their shape changes significantly on timescales of a few 100 Myr. Properties of magnetic arms can be controlled by changing the model parameters. In particular, a lower injection rate of small-scale field makes the magnetic configuration smoother and eliminates distinct magnetic arms. Conclusions: We conclude that magnetic arms can be considered as coherent magnetic structures generated by large-scale dynamo action, and associated with spatially modulated small-scale magnetic fluctuations, caused by enhanced star formation rates within the material arms.

Hydrogenated arsenenes as planar magnet and Dirac material

NASA Astrophysics Data System (ADS)

Zhang, Shengli; Hu, Yonghong; Hu, Ziyu; Cai, Bo; Zeng, Haibo

2015-07-01

Arsenene and antimonene are predicted to have 2.49 and 2.28 eV band gaps, which have aroused intense interest in the two-dimensional (2D) semiconductors for nanoelectronic and optoelectronic devices. Here, the hydrogenated arsenenes are reported to be planar magnet and 2D Dirac materials based on comprehensive first-principles calculations. The semi-hydrogenated (SH) arsenene is found to be a quasi-planar magnet, while the fully hydrogenated (FH) arsenene is a planar Dirac material. The buckling height of pristine arsenene is greatly decreased by the hydrogenation, resulting in a planar and relatively low-mass-density sheet. The electronic structures of arsenene are also evidently altered after hydrogenating from wide-band-gap semiconductor to metallic material for SH arsenene, and then to Dirac material for FH arsenene. The SH arsenene has an obvious magnetism, mainly contributed by the p orbital of the unsaturated As atom. Such magnetic and Dirac materials modified by hydrogenation of arsenene may have potential applications in future optoelectronic and spintronic devices.

Study of magnetic notions in the solar photosphere and their implications for heating the solar atmosphere

NASA Technical Reports Server (NTRS)

Noyes, Robert W.

1995-01-01

This progress report covers the first year of NASA Grant NAGw-2545, a study of magnetic structure in the solar photosphere and chromosphere. We have made significant progress in three areas: (1) analysis of vorticity in photospheric convection, which probably affects solar atmospheric heating through the stresses it imposes on photospheric magnetic fields; (2) modelling of the horizontal motions of magnetic footpoints in the solar photosphere using an assumed relation between brightness and vertical motion as well as continuity of flow; and (3) observations and analysis of infrared CO lines formed near the solar temperature minimum, whose structure and dynamics also yield important clues to the nature of heating of the upper atmosphere. Each of these areas are summarized in this report, with copies of those papers prepared or published this year included.

Characterization of a low frequency magnetic noise from a two-stage pulse tube cryocooler

NASA Astrophysics Data System (ADS)

Eshraghi, M. J.; Sasada, I.; Kim, J. M.; Lee, Y. H.

2009-07-01

Magnetic noise of a two-stage pulse tube cryocooler (PT) was measured by a fundamental mode orthogonal fluxgate magnetometer and by a LTS Double Relaxation Oscillation SQUID (DROS) first-order planar gradiometer. The magnetometer was installed in a dewar made of aluminum at 12 cm distance from a section containing magnetic regenerative materials of the second pulse tube. The magnetic noise spectrum showed a clear peak at 1.8 Hz, which is the fundamental frequency of the He gas pumping rate. The 1.8 Hz magnetic noise registered a peak, during the cooling down process, when the second cold-stage temperature was around 12 K, which is well correlated with the 1.8 Hz variation of the temperature of the second cold stage. Hence, we attributed the main source of this magnetic noise to the temperature variation of the magnetic moments resulting from magnetic regenerative materials, Er 3Ni and HoCu 2, in the presence of background static magnetic fields. We have also pointed out that the superconducting magnetic shield of lead sheets reduced the low frequency magnetic noise generated from the magnetic regenerative materials. With this arrangement, the magnetic noise amplitude measured with the LTS DROS gradiometer, mounted at 7 cm horizontal distance from the magnetic regenerative materials, in the optimum condition, was lower than 500 pT peak-to-peak, whereas the noise level without lead shielding was higher than the dynamic range of DROS instrumentations which was around ±10nT.

High frequency transformers and high Q factor inductors formed using epoxy-based magnetic polymer materials

DOEpatents

Sanchez, Robert O.; Gunewardena, Shelton; Masi, James V.

2007-11-27

An electrical component in the form of an inductor or transformer is disclosed which includes one or more coils and a magnetic polymer material located near the coils or supporting the coils to provide an electromagnetic interaction therewith. The magnetic polymer material is preferably a cured magnetic epoxy which includes a mercaptan derivative having a ferromagnetic atom chemically bonded therein. The ferromagnetic atom can be either a transition metal or rare-earth atom.

High frequency transformers and high Q factor inductors formed using epoxy-based magnetic polymer materials

DOEpatents

Sanchez, Robert O.; Gunewardena, Shelton; Masi, James V.

2005-03-29

An electrical component in the form of an inductor or transformer is disclosed which includes one or more coils and a magnetic polymer material located near the coils or supporting the coils to provide an electromagnetic interaction therewith. The magnetic polymer material is preferably a cured magnetic epoxy which includes a mercaptan derivative having a ferromagnetic atom chemically bonded therein. The ferromagnetic atom can be either a transition metal or rare-earth atom.

An overview of rotating machine systems with high-temperature bulk superconductors

NASA Astrophysics Data System (ADS)

Zhou, Difan; Izumi, Mitsuru; Miki, Motohiro; Felder, Brice; Ida, Tetsuya; Kitano, Masahiro

2012-10-01

The paper contains a review of recent advancements in rotating machines with bulk high-temperature superconductors (HTS). The high critical current density of bulk HTS enables us to design rotating machines with a compact configuration in a practical scheme. The development of an axial-gap-type trapped flux synchronous rotating machine together with the systematic research works at the Tokyo University of Marine Science and Technology since 2001 are briefly introduced. Developments in bulk HTS rotating machines in other research groups are also summarized. The key issues of bulk HTS machines, including material progress of bulk HTS, in situ magnetization, and cooling together with AC loss at low-temperature operation are discussed.

Recent Advances in Nanotechnology Applied to Biosensors

PubMed Central

Zhang, Xueqing; Guo, Qin; Cui, Daxiang

2009-01-01

In recent years there has been great progress the application of nanomaterials in biosensors. The importance of these to the fundamental development of biosensors has been recognized. In particular, nanomaterials such as gold nanoparticles, carbon nanotubes, magnetic nanoparticles and quantum dots have been being actively investigated for their applications in biosensors, which have become a new interdisciplinary frontier between biological detection and material science. Here we review some of the main advances in this field over the past few years, explore the application prospects, and discuss the issues, approaches, and challenges, with the aim of stimulating a broader interest in developing nanomaterial-based biosensors and improving their applications in disease diagnosis and food safety examination. PMID:22399954

Iron dominated magnets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fischer, G.E.

1985-07-01

These two lectures on iron dominated magnets are meant for the student of accelerator science and contain general treatments of the subjects design and construction. The material is arranged in the categories: General Concepts and Cost Considerations, Profile Configuration and Harmonics, Magnetic Measurements, a few examples of ''special magnets'' and Materials and Practices. Extensive literature is provided.

Magnetic materials selection for static inverter and converter transformers

NASA Technical Reports Server (NTRS)

Mclyman, C. W. T.

1971-01-01

Different magnetic alloys best suited for high-frequency and high-efficiency applications were comparatively investigated together with an investigation of each alloy's inherent characteristics. One of the characteristics in magnetic materials deterimental in transformer design is the residual flux density, which can be additive on turn-on and cause the transformer to saturate. Investigation of this problem led to the design of a transformer with a very low residual flux. Tests were performed to determine the dc and ac magnetic properties at 2400 Hz using square-wave excitation. These tests were performed on uncut cores, which were then cut for comparison of the gapped and ungapped magnetic properties. The optimum transformer was found to be that with the lowest residual flux and a small amount of air gap in the magnetic material. The data obtained from these tests are described, and the potential uses for the materials are discussed.

Complementary analyses of hollow cylindrical unioriented permanent magnet (HCM) with high permeability external layer

NASA Astrophysics Data System (ADS)

Lobo, Carlos M. S.; Tosin, Giancarlo; Baader, Johann E.; Colnago, Luiz A.

2017-10-01

In this article, several studies based on analytical expressions and computational simulations on Hollow Cylindrical Magnets with an external soft ferromagnetic material (HCM magnets) are presented. Electromagnetic configurations, as well as permanent-magnet-based structures, are studied in terms of magnetic field strength and homogeneity. Permanent-magnet-based structures are further analyzed in terms of the anisotropy of the magnetic permeability. It was found that the HCM magnets produce a highly homogeneous magnetic field as long as the magnetic material is isotropic. The dependency of the magnetic field strength and homogeneity in terms of the anisotropy of the magnetic permeability is also explored here. These magnets can potentially be used in medium-resolution NMR spectrometers and high-field NMR spectrometers.

Viking magnetic properties investigation: further results.

PubMed

Hargraves, R B; Collinson, D W; Arvidson, R E; Spitzer, C R

1976-12-11

The amounts of magnetic particles held on the reference test chart and backhoe magnets on lander 2 and lander 1 are comparable, indicating the presence of an estimated 3 to 7 percent by weight of relatively pure, strongly magnetic particles in the soil at the lander 2 sampling site. Preliminary spectrophotometric analysis of the material held on the backhoe magnets on lander 1 indicates that its reflectance characteristics are indistinguishable from material within a sampling trench with which it has been compared. The material on the RTC magnet shows a different spectrum, but it is suspected that the difference is the result of a reflectance contribution from the magnesium metal covering on the magnet. It is argued that the results indicate the presence, now or originally, of magnetite, which may be titaniferous.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, X., E-mail: Xiujuan.jiang@pnnl.gov

Soft magnetic materials are often limited in scalability due to conventional processes that do not retain beneficial microstructures, and their associated physical properties, during densification. In this work, friction consolidation (FC) has been studied to fabricate Fe−Si soft magnetic materials from gas-atomized powder precursors. Fe−Si powder is consolidated using variable pressure and tool rotation speed in an effort to evaluate this unique densification approach for potential improvements in magnetic properties. FC, due to the high shear deformation involved, is shown to result in uniform gradual grain structure refinement across the consolidated workpiece from the center nearest the tool to themore » edge. Magnetic properties along different orientations indicate little, if any, textural orientation in the refined grain structure. The effect of annealing on the magnetic properties is evaluated and shown to decrease coercivity. FC processing was able to retain the magnetization of the original gas-atomized powders but further process optimization is needed to reach the optimal coercivity for the soft magnetic materials applications. - Highlights: •Friction stir processing was utilized to consolidate Fe−Si soft magnetic powders. •The resultant microstructure and magnetic properties were correlated to the processing conditions. •Friction consolidation refined the grain size of the materials by ~ 40%. •Annealing successfully reduced the coercivity induced by the stress during processing. •The results shine light on the possible scaling up of nanostructured materials.« less

Magnetism: Principles and Applications

NASA Astrophysics Data System (ADS)

Craik, Derek J.

2003-09-01

If you are studying physics, chemistry, materials science, electrical engineering, information technology or medicine, then you'll know that understanding magnetism is fundamental to success in your studies and here is the key to unlocking the mysteries of magnetism....... You can: obtain a simple overview of magnetism, including the roles of B and H, resonances and special techniques take full advantage of modern magnets with a wealth of expressions for fields and forces develop realistic general design programmes using isoparametric finite elements study the subtleties of the general theory of magnetic moments and their dynamics follow the development of outstanding materials appreciate how magnetism encompasses topics as diverse as rock magnetism, chemical reaction rates, biological compasses, medical therapies, superconductivity and levitation understand the basis and remarkable achievements of magnetic resonance imaging In his new book, Magnetism, Derek Craik throws light on the principles and applications of this fascinating subject. From formulae for calculating fields to quantum theory, the secrets of magnetism are exposed, ensuring that whether you are a chemist or engineer, physicist, medic or materials scientist Magnetism is the book for our course.

Fast superconducting magnetic field switch

DOEpatents

Goren, Yehuda; Mahale, Narayan K.

1996-01-01

The superconducting magnetic switch or fast kicker magnet is employed with electron stream or a bunch of electrons to rapidly change the direction of flow of the electron stream or bunch of electrons. The apparatus employs a beam tube which is coated with a film of superconducting material. The tube is cooled to a temperature below the superconducting transition temperature and is subjected to a constant magnetic field which is produced by an external dc magnet. The magnetic field produced by the dc magnet is less than the critical field for the superconducting material, thus, creating a Meissner Effect condition. A controllable fast electromagnet is used to provide a magnetic field which supplements that of the dc magnet so that when the fast magnet is energized the combined magnetic field is now greater that the critical field and the superconducting material returns to its normal state allowing the magnetic field to penetrate the tube. This produces an internal field which effects the direction of motion and of the electron stream or electron bunch. The switch can also operate as a switching mechanism for charged particles.

Fast superconducting magnetic field switch

DOEpatents

Goren, Y.; Mahale, N.K.

1996-08-06

The superconducting magnetic switch or fast kicker magnet is employed with electron stream or a bunch of electrons to rapidly change the direction of flow of the electron stream or bunch of electrons. The apparatus employs a beam tube which is coated with a film of superconducting material. The tube is cooled to a temperature below the superconducting transition temperature and is subjected to a constant magnetic field which is produced by an external dc magnet. The magnetic field produced by the dc magnet is less than the critical field for the superconducting material, thus, creating a Meissner Effect condition. A controllable fast electromagnet is used to provide a magnetic field which supplements that of the dc magnet so that when the fast magnet is energized the combined magnetic field is now greater that the critical field and the superconducting material returns to its normal state allowing the magnetic field to penetrate the tube. This produces an internal field which effects the direction of motion and of the electron stream or electron bunch. The switch can also operate as a switching mechanism for charged particles. 6 figs.

Linking magnetite in the abdomen of honey bees to a magnetoreceptive function

PubMed Central

Lambinet, Veronika; Hayden, Michael E.; Reigl, Katharina; Gomis, Surath

2017-01-01

Previous studies of magnetoreception in honey bees, Apis mellifera, focused on the identification of magnetic material, its formation, the location of the receptor and potential underlying sensory mechanisms, but never directly linked magnetic material to a magnetoreceptive function. In our study, we demonstrate that ferromagnetic material consistent with magnetite plays an integral role in the bees' magnetoreceptor. Subjecting lyophilized and pelletized bee tagmata to analyses by a superconducting quantum interference device generated a distinct hysteresis loop for the abdomen but not for the thorax or the head of bees, indicating the presence of ferromagnetic material in the bee abdomen. Magnetic remanence of abdomen pellets produced from bees that were, or were not, exposed to the 2.2-kOe field of a magnet while alive differed, indicating that magnet exposure altered the magnetization of this magnetite in live bees. In behavioural two-choice field experiments, bees briefly exposed to the same magnet, but not sham-treated control bees, failed to sense a custom-generated magnetic anomaly, indicating that magnet exposure had rendered the bees' magnetoreceptor dysfunctional. Our data support the conclusion that honey bees possess a magnetite-based magnetoreceptor located in the abdomen. PMID:28330921

Linking magnetite in the abdomen of honey bees to a magnetoreceptive function.

PubMed

Lambinet, Veronika; Hayden, Michael E; Reigl, Katharina; Gomis, Surath; Gries, Gerhard

2017-03-29

Previous studies of magnetoreception in honey bees, Apis mellifera , focused on the identification of magnetic material, its formation, the location of the receptor and potential underlying sensory mechanisms, but never directly linked magnetic material to a magnetoreceptive function. In our study, we demonstrate that ferromagnetic material consistent with magnetite plays an integral role in the bees' magnetoreceptor. Subjecting lyophilized and pelletized bee tagmata to analyses by a superconducting quantum interference device generated a distinct hysteresis loop for the abdomen but not for the thorax or the head of bees, indicating the presence of ferromagnetic material in the bee abdomen. Magnetic remanence of abdomen pellets produced from bees that were, or were not, exposed to the 2.2-kOe field of a magnet while alive differed, indicating that magnet exposure altered the magnetization of this magnetite in live bees. In behavioural two-choice field experiments, bees briefly exposed to the same magnet, but not sham-treated control bees, failed to sense a custom-generated magnetic anomaly, indicating that magnet exposure had rendered the bees' magnetoreceptor dysfunctional. Our data support the conclusion that honey bees possess a magnetite-based magnetoreceptor located in the abdomen. © 2017 The Authors.

Theoretical study of local magnetocrystalline anisotropy of ɛ-Fe2O3

NASA Astrophysics Data System (ADS)

Hirai, Daisuke; Tsuneyuki, Shinji; Gohda, Yoshihiro

2015-03-01

Magnetocrystalline anisotropy (MCA) is positively correlated with corercivity that is one of important magnetic figures of merit for applications such as high-density magnetic recording media, high-frequency electromagnetic wave absorbers, and permanent magnets. In general, MCA is given for an entire phase of a material. In light of materials engineering, however, MCA information at respective atoms in crystals is useful to identify weak parts for possible nucleation cores of magnetic reversal and design the local MCA. Considering these facts, we examined the local MCA of hard magnetic materials on the basis of density functional theory and the second perturbation theory on spin-orbit interaction. We studied the magnetic properties of ɛ-Fe2O3, which shows the largest coercivity among all the metal oxides. Particularly, we tried to elucidate the effect of an oxygen vacancy on the magnetic properties. As a result, we clarified that the vacancy enhances both the magnetic moment and MAE. We acknowledge partial financial support from the Elemental Strategy Initiative Center for Magnetic Materials (ESICMM) under outsourcing project of MEXT. The computation was partly carried out on the K-computer (Grant No. hp120086).

Modeling Instruction in AP Physics C: Mechanics and Electricity and Magnetism

ERIC Educational Resources Information Center

Belcher, Nathan Tillman

2017-01-01

This action research study used data from multiple assessments in Mechanics and Electricity and Magnetism to determine the viability of Modeling Instruction as a pedagogy for students in AP Physics C: Mechanics and Electricity and Magnetism. Modeling Instruction is a guided-inquiry approach to teaching science in which students progress through…

Employing Magnetic Levitation to Monitor Reaction Kinetics and Measure Activation Energy

ERIC Educational Resources Information Center

Benz, Lauren; Cesafsky, Karen E.; Le, Tran; Park, Aileen; Malicky, David

2012-01-01

This article describes a simple and inexpensive undergraduate-level kinetics experiment that uses magnetic levitation to monitor the progress and determine the activation energy of a condensation reaction on a polymeric solid support. The method employs a cuvette filled with a paramagnetic solution positioned between two strong magnets. The…

Preparation and evaluation of magnetic carbonaceous materials for pesticide and metal removal.

PubMed

Ohno, Masaki; Hayashi, Hiroki; Suzuki, Kazuyuki; Kose, Tomohiro; Asada, Takashi; Kawata, Kuniaki

2011-07-15

Magnetic carbonaceous materials were produced by carbonization of a cation exchange resin loaded with ferrous or ferric iron and activation using sieved oyster shell as the activation agent. The magnetic carbonaceous material with the maximum magnetic flux density on every axis (ESS-1) was obtained from the ferric-loaded resin by carbonization at 700°C, followed by activation with the oyster shell at 900°C, and magnetization. A separate step of carbonization and activation appears to cause more of a reduction reaction of Fe to form γ-Fe(2)O(3). The Fe compound in the magnetic carbonaceous material was identified from the XRD pattern as mainly γ-Fe(2)O(3). The magnetic flux density on every axis increased linearly as the amount of the oyster shell increased. Moreover, the adsorption ability of the products was evaluated for pesticides and metal ions. Both ESS-1 and a carbonaceous material obtained from the resin without ferric ion (RC) appear to have the highest adsorption ability for lead. Furthermore, the adsorption ability of ESS-1 might decrease by blockages of the pores with the loaded Fe compounds. Copyright © 2011 Elsevier Inc. All rights reserved.

Magnetic particle translation as a surrogate measure for synovial fluid mechanics.

PubMed

Shah, Yash Y; Maldonado-Camargo, Lorena; Patel, Neal S; Biedrzycki, Adam H; Yarmola, Elena G; Dobson, Jon; Rinaldi, Carlos; Allen, Kyle D

2017-07-26

The mechanics of synovial fluid vary with disease progression, but are difficult to quantify quickly in a clinical setting due to small sample volumes. In this study, a novel technique to measure synovial fluid mechanics using magnetic nanoparticles is introduced. Briefly, microspheres embedded with superparamagnetic iron oxide nanoparticles, termed magnetic particles, are distributed through a 100μL synovial fluid sample. Then, a permanent magnet inside a protective sheath is inserted into the synovial fluid sample. Magnetic particles translate toward the permanent magnet and the percentage of magnetic particles collected by the magnet in a given time can be related to synovial fluid viscosity. To validate this relationship, magnetic particle translation was demonstrated in three phases. First, magnetic particle translation was assessed in glycerol solutions with known viscosities, demonstrating that as fluid viscosity increased, magnetic particle translation decreased. Next, the relationship between magnetic particle translation and synovial fluid viscosity was assessed using bovine synovial fluid that was progressively degenerated via ultrasonication. Here, particle collection in a given amount of time increased as fluid degenerated, demonstrating that the relationship between particle collection and fluid mechanics holds in non-Newtonian synovial fluid. Finally, magnetic particle translation was used to assess differences between healthy and OA affected joints in equine synovial fluid. Here, particle collection in a given time was higher in OA joints relative to healthy horses (p<0.001). Combined, these data demonstrate potential viability of magnetic particle translation in a clinical setting to evaluate synovial fluid mechanics in limited volumes of synovial fluid sample. Copyright © 2017 Elsevier Ltd. All rights reserved.

Distinguishing Between Activated and Non-Activated Eosinophils Using a Microelectrode: Theoretical Investigations of Bulk and Surface Polaritons in Magnetic Multilayers

NASA Astrophysics Data System (ADS)

Lacy, Fred

In Part I of this dissertation, a whole cell biosensor which can detect the activation state of eosinophils (one of several types of white blood cells) will be developed and tested. This biosensor, which consists of a small gold electrode (50 μm x 50 μm) and a large gold electrode (1.5 cm x 0.5 cm) on a glass substrate, has been fabricated by photolithographic techniques. The eosinophils are known to exhibit different physical properties when they change from the activated state to the non-activated state. Based on some of these property changes, there should be a corresponding change in the measured electrical impedance. In this research, this biosensor will measure the electrical impedance of the eosinophils. This will show that the biosensor can detect the different states of the eosinophils (through the electrical impedance technique). And from these measurements, the different parameters associated with the electrical impedance can be determined. In Part II of this dissertation, a theoretical calculation will be performed in which bulk and surface magnetic polaritons in magnetic materials will be found. A polariton is the coupling of electromagnetic radiation and the elementary excitation of the given material (in our case, a magnetic material). The structure that we will be considering is a periodic semi-infinite material consisting of alternating antiferromagnetic and nonmagnetic layers. An antiferromagnetic material is a material in which individual atoms exhibit magnetic moments, but the overall magnetization of the material is zero because the moments of every other atom are antiparallel. We will use a method known as the transfer matrix technique to find an expression for the dispersion relation of the bulk and surface waves in these materials. Then we will create plots of omega(k) as we vary the geometric configurations of the layers which make-up the magnetic multilayer. We also will calculate the effect of an external magnetic field on these magnetic structures.

Development of Y-Ba-Cu-O Superconductors for Magnetic Bearings

NASA Technical Reports Server (NTRS)

Selvamanickam, V.; Pfaffenbach, K.; Sokolowski, R. S.; Zhang, Y.; Salama, K.

1996-01-01

The material requirements, material manufacturing and magnetic properties that are relevant to fabrication of High Temperature Superconductor (HTS) magnetic bearings have been discussed. It is found that the seeded-melt-texturing method can be used to fabricate the single domain material that is required to achieve the best magnetic properties. Trapped-field mapping has been used as a non-destructive tool to determine the single-domain nature of the HTS material and quantity of the HTS disks. Both the trapped field and the levitation force of the Y-Ba-Cu-O disks are found to be strongly sensitive to the oxygen content.

Method and apparatus for separating materials magnetically. [Patent application; iron pyrite from coal

DOEpatents

Hise, E.C. Jr.; Holman, A.S.; Friedlaender, F.J.

1980-11-06

Magnetic and nonmagnetic materials are separated by passing stream thereof past coaxial current-carrying coils which produce a magnetic field wherein intensity varies sharply with distance radially of the axis of the coils.

Structure and magnetic properties of mechanically alloyed Co and Co-Ni

NASA Astrophysics Data System (ADS)

Guessasma, S.; Fenineche, N.

The influence of milling process on magnetic properties of Co and Co-Ni materials is studied. Coercivity, squareness ratio and crystallite size of mechanically alloyed Co-Ni material were related to milling time. For Co material, coercivity, cubic phase ratio and crystallite size were related to milling energy considering the vial and plateau rotation velocities. An artificial neural network (ANN) combining the parameters for both materials is used to predict magnetic and structure results versus milling conditions. Predicted results showed that milling energy is mostly dependent on the ratio vial to plateau rotation velocities and that milling times larger than 40 h do not add significant change to both structure and magnetic responses. Magnetic parameters were correlated to crystallite size and the D 6 law was only valid for small sizes.

Nano-magnetic particles used in biomedicine: core and coating materials.

PubMed

Karimi, Z; Karimi, L; Shokrollahi, H

2013-07-01

Magnetic nanoparticles for medical applications have been developed by many researchers. Separation, immunoassay, drug delivery, magnetic resonance imaging and hyperthermia are enhanced by the use of suitable magnetic nanoparticles and coating materials in the form of ferrofluids. Due to their low biocompatibility and low dispersion in water solutions, nanoparticles that are used for biomedical applications require surface treatment. Various kinds of coating materials including organic materials (polymers), inorganic metals (gold, platinum) or metal oxides (aluminum oxide, cobalt oxide) have been attracted during the last few years. Based on the recent advances and the importance of nanomedicine in human life, this paper attempts to give a brief summary on the different ferrite nano-magnetic particles and coatings used in nanomedicine. Copyright © 2013 Elsevier B.V. All rights reserved.

Engineered materials for all-optical helicity-dependent magnetic switching

NASA Astrophysics Data System (ADS)

Fullerton, Eric

2014-03-01

The possibilities of manipulating magnetization without applied magnetic fields have attracted growing attention over the last fifteen years. The low-power manipulation of magnetization, preferably at ultra-short time scales, has become a fundamental challenge with implications for future magnetic information memory and storage technologies. Here we explore the optical manipulation of the magnetization of engineered materials and devices using 100 fs optical pulses. We demonstrate that all optical - helicity dependent switching (AO-HDS) can be observed not only in selected rare-earth transition-metal (RE-TM) alloy films but also in a much broader variety of materials, including alloys, multilayers, heterostructures and RE-free Co-Ir-based synthetic ferrimagnets. The discovery of AO-HDS in RE-free TM-based synthetic ferrimagnets can enable breakthroughs for numerous applications since it exploits materials that are currently used in magnetic data storage, memories and logic technologies. In addition, this materials study of AO-HDS offers valuable insight into the underlying mechanisms involved. Indeed the common denominator of the diverse structures showing AO-HDS in this study is that two ferromagnetic sub-lattices exhibit magnetization compensation (and therefore angular momentum compensation) at temperatures near or above room temperature. We are highlighting that compensation plays a major role and that this compensation can be established at the atomic level as in alloys but also over a larger nanometers scale as in the multilayers or in heterostructures. We will also discuss the potential to extend AO-HDS to new classes of magnetic materials. This work was done in collaboration with S. Mangin, M. Gottwald, C-H. Lambert, D. Steil, V. Uhlíř, L. Pang, M. Hehn, S. Alebrand, M. Cinchetti, G. Malinowski, Y. Fainman, and M. Aeschlimann. Supported by the ANR-10-BLANC-1005 ``Friends,'' a grant from the Advanced Storage Technology Consortium, Partner University Fund ``Novel Magnetic Materials for Spin Torque Physics'' as well as the European Project (OP2M FP7-IOF-2011-298060).

Elastic magnetic composites for energy storage flywheels

DOE PAGES

Martin, James E.; Rohwer, Lauren E. S.; Stupak, Jr., Joseph

2016-05-05

The bearings used in energy storage flywheels dissipate a significant amount of energy and can fail catastrophically. Magnetic bearings would both reduce energy dissipation and increase flywheel reliability. The component of magnetic bearing that creates lift is a magnetically soft material embedded into a rebate cut into top of the inner annulus of the flywheel. Because the flywheels stretch about 1% as they spin up, this magnetic material must also stretch and be more compliant than the flywheel itself, so it does not part from the flywheel during spin up. At the same time, the material needs to be sufficientlymore » stiff that it does not significantly deform in the rebate and must have a sufficiently large magnetic permeability and saturation magnetization to provide the required lift. It must also have high electrical resistivity to prevent heating due to eddy currents. In this paper we investigate whether adequately magnetic, mechanically stiff composites that have the tensile elasticity, high electrical resistivity, permeability and saturation magnetism required for flywheel lift magnet applications can be fabricated. Lastly, we find the best composites are those comprised of bidisperse Fe particles in the resin G/Flex 650. The primary limiting factor of such materials is the fatigue resistance to tensile strain.« less

Evaluation of Stress Distribution in Magnetic Materials Using a Magnetic Imaging System

NASA Astrophysics Data System (ADS)

Lo, C. C. H.; Paulsen, J. A.; Jiles, D. C.

2004-02-01

The feasibility of detecting stress distribution in magnetic materials by magnetic hysteresis and Barkhausen effect measurements has been evaluated using a newly developed magnetic imaging system. The system measured hysteresis loops and Barkhausen effect signals with the use of a surface sensor that was scanned over the material. The data were converted into a two-dimensional image showing spatial variations of the magnetic properties from which mechanical conditions of the materials can be inferred. In this study a nickel plate machined into a shear-beam load cell configuration was used. By applying a stress along the neutral axis, various stress patterns such as shear stress and stress concentration could be produced in different regions of the sample. The scanned images of magnetic properties such as coercivity and rms value of Barkhausen effect signal exhibited patterns similar to the stress distribution calculated using finite element model (FEM), in particular in the regions where a high stress level and a high stress gradient existed. For direct comparison, images of magnetic properties were simulated based on the results of FEM stress calculation and experimental calibration of the magnetomechanical effect. The simulated images were found to closely resemble the scanned images, indicating the possibility of measuring stress distribution by mapping magnetic properties using the magnetic imaging system.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Esa, Mohammad Faris Mohammad; Hassan, Ibrahim Haji; Rahim, Faszly

Magnetic material such as magnetite are known as particles that respond to external magnetic field with their ferromagnetic properties as they are believed contribute to in responding to the geomagnetic field. These particles are used by terrestrial animals such as termites for navigation and orientation. Since our earth react as giant magnetic bar, the magnitude of this magnetic field present by intensity and direction (inclination and direction). The magnetic properties and presence of magnetite in termites Macrotermes gilvus, common mound-building termite were tested. M. gilvus termites was tested with a Vibrating Sample Magnetometer VSM to determine the magnetic properties ofmore » specimen. The crushed body sample was characterized with X-Ray Diffraction XRD to show the existent of magnetic material (magnetite) in the specimens. Results from VSM indicate that M. gilvus has diamagnetism properties. The characterization by XRD shows the existent of magnetic material in our specimen in low concentration.« less

Low-Cost Magnetic Stirrer from Recycled Computer Parts with Optional Hot Plate

ERIC Educational Resources Information Center

Guidote, Armando M., Jr.; Pacot, Giselle Mae M.; Cabacungan, Paul M.

2015-01-01

Magnetic stirrers and hot plates are key components of science laboratories. However, these are not readily available in many developing countries due to their high cost. This article describes the design of a low-cost magnetic stirrer with hot plate from recycled materials. Some of the materials used are neodymium magnets and CPU fans from…

Tunable dynamic response of magnetic gels: Impact of structural properties and magnetic fields

NASA Astrophysics Data System (ADS)

Tarama, Mitsusuke; Cremer, Peet; Borin, Dmitry Y.; Odenbach, Stefan; Löwen, Hartmut; Menzel, Andreas M.

2014-10-01

Ferrogels and magnetic elastomers feature mechanical properties that can be reversibly tuned from outside through magnetic fields. Here we concentrate on the question of how their dynamic response can be adjusted. The influence of three factors on the dynamic behavior is demonstrated using appropriate minimal models: first, the orientational memory imprinted into one class of the materials during their synthesis; second, the structural arrangement of the magnetic particles in the materials; and third, the strength of an external magnetic field. To illustrate the latter point, structural data are extracted from a real experimental sample and analyzed. Understanding how internal structural properties and external influences impact the dominant dynamical properties helps to design materials that optimize the requested behavior.

Development of a low-cost double rotor axial flux motor with soft magnetic composite and ferrite permanent magnet materials

NASA Astrophysics Data System (ADS)

Liu, Chengcheng; Zhu, Jianguo; Wang, Youhua; Guo, Youguang; Lei, Gang; Liu, Xiaojing

2015-05-01

This paper proposes a low-cost double rotor axial flux motor (DRAFM) with low cost soft magnetic composite (SMC) core and ferrite permanent magnets (PMs). The topology and operating principle of DRAFM and design considerations for best use of magnetic materials are presented. A 905 W 4800 rpm DRAFM is designed for replacing the high cost NdFeB permanent magnet synchronous motor (PMSM) in a refrigerator compressor. By using the finite element method, the electromagnetic parameters and performance of the DRAFM operated under the field oriented control scheme are calculated. Through the analysis, it is shown that that the SMC and ferrite PM materials can be good candidates for low-cost electric motor applications.

Modelling of the material flow of Nd-Fe-B magnets under high temperature deformation via finite element simulation method

PubMed Central

Chen, Yen-Ju; Lee, Yen-I; Chang, Wen-Cheng; Hsiao, Po-Jen; You, Jr-Shian; Wang, Chun-Chieh; Wei, Chia-Min

2017-01-01

Abstract Hot deformation of Nd-Fe-B magnets has been studied for more than three decades. With a good combination of forming processing parameters, the remanence and (BH)max values of Nd-Fe-B magnets could be greatly increased due to the formation of anisotropic microstructures during hot deformation. In this work, a methodology is proposed for visualizing the material flow in hot-deformed Nd-Fe-B magnets via finite element simulation. Material flow in hot-deformed Nd-Fe-B magnets could be predicted by simulation, which fitted with experimental results. By utilizing this methodology, the correlation between strain distribution and magnetic properties enhancement could be better understood. PMID:28970869

Theory of scanning tunneling spectroscopy: from Kondo impurities to heavy fermion materials

NASA Astrophysics Data System (ADS)

Morr, Dirk K.

2017-01-01

Kondo systems ranging from the single Kondo impurity to heavy fermion materials present us with a plethora of unconventional properties whose theoretical understanding is still one of the major open problems in condensed matter physics. Over the last few years, groundbreaking scanning tunneling spectroscopy (STS) experiments have provided unprecedented new insight into the electronic structure of Kondo systems. Interpreting the results of these experiments—the differential conductance and the quasi-particle interference spectrum—however, has been complicated by the fact that electrons tunneling from the STS tip into the system can tunnel either into the heavy magnetic moment or the light conduction band states. In this article, we briefly review the theoretical progress made in understanding how quantum interference between these two tunneling paths affects the experimental STS results. We show how this theoretical insight has allowed us to interpret the results of STS experiments on a series of heavy fermion materials providing detailed knowledge of their complex electronic structure. It is this knowledge that is a conditio sine qua non for developing a deeper understanding of the fascinating properties exhibited by heavy fermion materials, ranging from unconventional superconductivity to non-Fermi-liquid behavior in the vicinity of quantum critical points.

Magnetic separation of general solid particles realised by a permanent magnet

PubMed Central

Hisayoshi, K.; Uyeda, C.; Terada, K.

2016-01-01

Most existing solids are categorised as diamagnetic or weak paramagnetic materials. The possibility of magnetic motion has not been intensively considered for these materials. Here, we demonstrate for the first time that ensembles of heterogeneous particles (diamagnetic bismuth, diamond and graphite particles, as well as two paramagnetic olivines) can be dynamically separated into five fractions by the low field produced by neodymium (NdFeB) magnets during short-duration microgravity (μg). This result is in contrast to the generally accepted notion that ordinary solid materials are magnetically inert. The materials of the separated particles are identified by their magnetic susceptibility (χ), which is determined from the translating velocity. The potential of this approach as an analytical technique is comparable to that of chromatography separation because the extraction of new solid phases from a heterogeneous grain ensemble will lead to important discoveries about inorganic materials. The method is applicable for the separation of the precious samples such as lunar soils and/or the Hayabusa particles recovered from the asteroids, because even micron-order grains can be thoroughly separated without sample-loss. PMID:27929081

Magnetic separation of general solid particles realised by a permanent magnet

NASA Astrophysics Data System (ADS)

Hisayoshi, K.; Uyeda, C.; Terada, K.

2016-12-01

Most existing solids are categorised as diamagnetic or weak paramagnetic materials. The possibility of magnetic motion has not been intensively considered for these materials. Here, we demonstrate for the first time that ensembles of heterogeneous particles (diamagnetic bismuth, diamond and graphite particles, as well as two paramagnetic olivines) can be dynamically separated into five fractions by the low field produced by neodymium (NdFeB) magnets during short-duration microgravity (μg). This result is in contrast to the generally accepted notion that ordinary solid materials are magnetically inert. The materials of the separated particles are identified by their magnetic susceptibility (χ), which is determined from the translating velocity. The potential of this approach as an analytical technique is comparable to that of chromatography separation because the extraction of new solid phases from a heterogeneous grain ensemble will lead to important discoveries about inorganic materials. The method is applicable for the separation of the precious samples such as lunar soils and/or the Hayabusa particles recovered from the asteroids, because even micron-order grains can be thoroughly separated without sample-loss.

Magnetic separation of general solid particles realised by a permanent magnet.

PubMed

Hisayoshi, K; Uyeda, C; Terada, K

2016-12-08

Most existing solids are categorised as diamagnetic or weak paramagnetic materials. The possibility of magnetic motion has not been intensively considered for these materials. Here, we demonstrate for the first time that ensembles of heterogeneous particles (diamagnetic bismuth, diamond and graphite particles, as well as two paramagnetic olivines) can be dynamically separated into five fractions by the low field produced by neodymium (NdFeB) magnets during short-duration microgravity (μg). This result is in contrast to the generally accepted notion that ordinary solid materials are magnetically inert. The materials of the separated particles are identified by their magnetic susceptibility (χ), which is determined from the translating velocity. The potential of this approach as an analytical technique is comparable to that of chromatography separation because the extraction of new solid phases from a heterogeneous grain ensemble will lead to important discoveries about inorganic materials. The method is applicable for the separation of the precious samples such as lunar soils and/or the Hayabusa particles recovered from the asteroids, because even micron-order grains can be thoroughly separated without sample-loss.

Elementary Science-Magnet School Student Attitudes toward Science as Measured by Selected National Assessment of Educational Progress Items and Achievement in Science: A Replication and Extension.

ERIC Educational Resources Information Center

Solomon, Alan; Rachild, Bruce

Attitudes toward science of magnet school students were compared with those of their counterparts in two regular schools. This study attempted to replicate the findings of a 1988 study by A. Solomon and J. Wroblewski involving the same magnet school, the John Moffett Neighborhood Elementary Science Magnet School located in North Philadelphia…

Magnetic nanoparticle-based cancer nanodiagnostics

NASA Astrophysics Data System (ADS)

Zubair, Yousaf Muhammad; Yu, Jing; Hou, Yang-Long; Gao, Song

2013-05-01

Diagnosis facilitates the discovery of an impending disease. A complete and accurate treatment of cancer depends heavily on its early medical diagnosis. Cancer, one of the most fatal diseases world-wide, consistently affects a larger number of patients each year. Magnetism, a physical property arising from the motion of electrical charges, which causes attraction and repulsion between objects and does not involve radiation, has been under intense investigation for several years. Magnetic materials show great promise in the application of image contrast enhancement to accurately image and diagnose cancer. Chelating gadolinium (Gd III) and magnetic nanoparticles (MNPs) have the prospect to pave the way for diagnosis, operative management, and adjuvant therapy of different kinds of cancers. The potential of MNP-based magnetic resonance (MR) contrast agents (CAs) now makes it possible to image portions of a tumor in parts of the body that would be unclear with the conventional magnetic resonance imaging (MRI). Multiple functionalities like variety of targeting ligands and image contrast enhancement have recently been added to the MNPs. Keeping aside the additional complexities in synthetic steps, costs, more convoluted behavior, and effects in-vivo, multifunctional MNPs still face great regulatory hurdles before clinical availability for cancer patients. The trade-off between additional functionality and complexity is a subject of ongoing debate. The recent progress regarding the types, design, synthesis, morphology, characterization, modification, and the in-vivo and in-vitro uses of different MRI contrast agents, including MNPs, to diagnose cancer will be the focus of this review. As our knowledge of MNPs' characteristics and applications expands, their role in the future management of cancer patients will become very important. Current hurdles are also discussed, along with future prospects of MNPs as the savior of cancer victims.

Complementary analyses of hollow cylindrical unioriented permanent magnet (HCM) with high permeability external layer.

PubMed

Lobo, Carlos M S; Tosin, Giancarlo; Baader, Johann E; Colnago, Luiz A

2017-10-01

In this article, several studies based on analytical expressions and computational simulations on Hollow Cylindrical Magnets with an external soft ferromagnetic material (HCM magnets) are presented. Electromagnetic configurations, as well as permanent-magnet-based structures, are studied in terms of magnetic field strength and homogeneity. Permanent-magnet-based structures are further analyzed in terms of the anisotropy of the magnetic permeability. It was found that the HCM magnets produce a highly homogeneous magnetic field as long as the magnetic material is isotropic. The dependency of the magnetic field strength and homogeneity in terms of the anisotropy of the magnetic permeability is also explored here. These magnets can potentially be used in medium-resolution NMR spectrometers and high-field NMR spectrometers. Copyright © 2017 Elsevier Inc. All rights reserved.

Chemically Responsive Elastomers Exhibiting Unity-Order Refractive Index Modulation.

PubMed

Wu, Di M; Solomon, Michelle L; Naik, Gururaj V; García-Etxarri, Aitzol; Lawrence, Mark; Salleo, Alberto; Dionne, Jennifer A

2018-02-01

Chameleons are masters of light, expertly changing their color, pattern, and reflectivity in response to their environment. Engineered materials that share this tunability can be transformative, enabling active camouflage, tunable holograms, and novel colorimetric medical sensors. While progress has been made in creating artificial chameleon skin, existing schemes often require external power, are not continuously tunable, and may prove too stiff or bulky for applications. Here, a chemically tunable, large-area metamaterial is demonstrated that accesses a wide range of colors and refractive indices. An ordered monolayer of nanoresonators is fabricated, then its optical response is dynamically tuned by infiltrating its polymer substrate with solvents. The material shows a strong magnetic response with a dependence on resonator spacing that leads to a highly tunable effective permittivity, permeability, and refractive index spanning negative and positive values. The unity-order index tuning exceeds that of traditional electro-optic and photochromic materials and is robust to cycling, providing a path toward programmable optical elements and responsive light routing. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Composite particles formed by complexation of poly(methacrylic acid) - stabilized magnetic fluid with chitosan: Magnetic material for bioapplications.

PubMed

Safarik, Ivo; Stepanek, Miroslav; Uchman, Mariusz; Slouf, Miroslav; Baldikova, Eva; Nydlova, Leona; Pospiskova, Kristyna; Safarikova, Mirka

2016-10-01

A simple procedure for the synthesis of magnetic fluid (ferrofluid) stabilized by poly(methacrylic acid) has been developed. This ferrofluid was used to prepare a novel type of magnetically responsive chitosan-based composite material. Both ferrofluid and magnetic chitosan composite were characterized by a combination of microscopy (optical microscopy, TEM, SEM), scattering (static and dynamic light scattering, SANS) and spectroscopy (FTIR) techniques. Magnetic chitosan was found to be a perspective material for various bioapplications, especially as a magnetic carrier for immobilization of enzymes and cells. Lipase from Candida rugosa was covalently attached after cross-linking and activation of chitosan using glutaraldehyde. Baker's yeast cells (Saccharomyces cerevisiae) were incorporated into the chitosan composite during its preparation; both biocatalysts were active after reaction with appropriate substrates. Copyright © 2016 Elsevier B.V. All rights reserved.

Magnetic Field-Induced Phase Transformation in Magnetic Shape Memory Alloys with High Actuation Stress and Work Output

DTIC Science & Technology

2010-05-03

Mechanisms for Advanced Properties in Phase Transforming Materials , Materials Science & Technology 2009 Conference, October 25-29, 2009, Pittsburgh, PA...Advanced Properties in Phase Transforming Materials , Materials Science & Technology 2009 Conference, October 25-29, 2009, Pittsburgh, PA, 2009. 11...observed materials behavior. Indeed, measured materials properties were found not to be the exact indication of the materials real response

Comparison of O-(2-18F-Fluoroethyl)-L-Tyrosine Positron Emission Tomography and Perfusion-Weighted Magnetic Resonance Imaging in the Diagnosis of Patients with Progressive and Recurrent Glioma: A Hybrid Positron Emission Tomography/Magnetic Resonance Study.

PubMed

Verger, Antoine; Filss, Christian P; Lohmann, Philipp; Stoffels, Gabriele; Sabel, Michael; Wittsack, Hans-J; Kops, Elena Rota; Galldiks, Norbert; Fink, Gereon R; Shah, Nadim J; Langen, Karl-Josef

2018-05-01

To compare the diagnostic performance of O-(2- 18 F-fluoroethyl)-L-tyrosine ( 18 F-FET) positron emission tomography (PET) and perfusion-weighted magnetic resonance imaging (PWI) for the diagnosis of progressive or recurrent glioma. Thirty-two pretreated gliomas (25 progressive or recurrent tumors, 7 treatment-related changes) were investigated with 18 F-FET PET and PWI via a hybrid PET/magnetic resonance scanner. Volumes of interest with a diameter of 16 mm were centered on the maximum of abnormality in the tumor area in PET and PWI maps (relative cerebral blood volume, relative cerebral blood flow, mean transit time) and the contralateral unaffected hemisphere. Mean and maximum tumor-to-brain ratios as well as dynamic data for 18 F-FET uptake were calculated. Diagnostic accuracies were evaluated by receiver operating characteristic analyses, calculating the area under the curve. 18 F-FET PET showed a significant greater sensitivity to detect abnormalities in pretreated gliomas than PWI (76% vs. 52%, P = 0.03). The maximum tumor-to-brain ratio of 18 F-FET PET was the only parameter that discriminated treatment-related changes from progressive or recurrent gliomas (area under the curve, 0.78; P = 0.03, best cut-off 2.61; sensitivity 80%, specificity 86%, accuracy 81%). Among patients with signal abnormality in both modalities, 75% revealed spatially incongruent local hot spots. This pilot study suggests that 18 F-FET PET is superior to PWI to diagnose progressive or recurrent glioma. Copyright © 2018 Elsevier Inc. All rights reserved.

Search for magnetic monopoles in lunar material

NASA Technical Reports Server (NTRS)

Alvarez, L. W.; Eberhard, P. H.; Ross, R. R.; Watt, R. D.

1972-01-01

Magnetic monopoles in 19.8 kg. of lunar material returned by Apollo 11, 12 and 14 missions were investigated. The search was done with a detector which is capable of detecting any single monopole of any charge equal to or larger than the minimum value compatible with Dirac's theory. Two experiments were performed, each one with different lunar material. In each experiment the lunar material was divided into several measurement samples. No monopole was found. The magnetic charge of each sample was consistent with zero.

Magnetic microscopy/metrology potential of metamaterials using nanosized spherical particle arrays

NASA Astrophysics Data System (ADS)

Eason, Kwaku; Luk'yanchuk, Boris; Zhou, Yi; Miroshnichenko, Andrey E.; Kivshar, Yuri S.

2011-12-01

Techniques for imaging and characterizing magnetic samples have been widely used in many areas of research involving magnetic materials. Nowadays, magnetic microscopy techniques play a critical role in characterizing magnetic thin film structures. In considering the various techniques, optical techniques offer some unique advantages over alternative techniques (e.g. MFM), as they are least affected by magnetic noise and, for the same underlying reasons, have also proven to be more suitable for "high speed" magnetization measurements of magnetization dynamics, which are increasingly important in many of today's research scopes. At the same time, development of metamaterials are opening the doors for newly behaving materials, such as those demonstrating negative refractive index, potentially useful in a variety of applications, such as imaging. Metamaterials deploying arrays of silicon particles, and even alternating silicon particles and split ring resonators have recently been shown to demonstrate interesting behavior, such as negative magnetic susceptibility and large resonant peaks in the Terahertz regime. Such high frequencies offer the potential bandwidth of extraordinarily fast dynamics, which are increasingly being generated in magnetic materials, for example, in optically-induced demagnetization and all-optical magnetic recording. Here, initial investigations toward ultra high-speed imaging and/or information extraction from magnetic samples is discussed considering metamaterials deploying mainly spherical particle arrays. In addition to the frequency spectrums of the system, the response of the system to external magnetic fields and background permeability changes due to external fields are investigated. Our results suggest a significant potential of metamaterials for use in probing information from magnetic materials.

Field-controlled structures in ferromagnetic cholesteric liquid crystals.

PubMed

Medle Rupnik, Peter; Lisjak, Darja; Čopič, Martin; Čopar, Simon; Mertelj, Alenka

2017-10-01

One of the advantages of anisotropic soft materials is that their structures and, consequently, their properties can be controlled by moderate external fields. Whereas the control of materials with uniform orientational order is straightforward, manipulation of systems with complex orientational order is challenging. We show that a variety of structures of an interesting liquid material, which combine chiral orientational order with ferromagnetic one, can be controlled by a combination of small magnetic and electric fields. In the suspensions of magnetic nanoplatelets in chiral nematic liquid crystals, the platelet's magnetic moments orient along the orientation of the liquid crystal and, consequently, the material exhibits linear response to small magnetic fields. In the absence of external fields, orientations of the liquid crystal and magnetization have wound structure, which can be either homogeneously helical, disordered, or ordered in complex patterns, depending on the boundary condition at the surfaces and the history of the sample. We demonstrate that by using different combinations of small magnetic and electric fields, it is possible to control reversibly the formation of the structures in a layer of the material. In such a way, different periodic structures can be explored and some of them may be suitable for photonic applications. The material is also a convenient model system to study chiral magnetic structures, because it is a unique liquid analog of a solid helimagnet.

Ab initio density-functional calculations in materials science: from quasicrystals over microporous catalysts to spintronics.

PubMed

Hafner, Jürgen

2010-09-29

During the last 20 years computer simulations based on a quantum-mechanical description of the interactions between electrons and atomic nuclei have developed an increasingly important impact on materials science, not only in promoting a deeper understanding of the fundamental physical phenomena, but also enabling the computer-assisted design of materials for future technologies. The backbone of atomic-scale computational materials science is density-functional theory (DFT) which allows us to cast the intractable complexity of electron-electron interactions into the form of an effective single-particle equation determined by the exchange-correlation functional. Progress in DFT-based calculations of the properties of materials and of simulations of processes in materials depends on: (1) the development of improved exchange-correlation functionals and advanced post-DFT methods and their implementation in highly efficient computer codes, (2) the development of methods allowing us to bridge the gaps in the temperature, pressure, time and length scales between the ab initio calculations and real-world experiments and (3) the extension of the functionality of these codes, permitting us to treat additional properties and new processes. In this paper we discuss the current status of techniques for performing quantum-based simulations on materials and present some illustrative examples of applications to complex quasiperiodic alloys, cluster-support interactions in microporous acid catalysts and magnetic nanostructures.

Direct Determination of Atomic Structure and Magnetic Coupling of Magnetite Twin Boundaries.

PubMed

Chen, Chunlin; Li, Hongping; Seki, Takehito; Yin, Deqiang; Sanchez-Santolino, Gabriel; Inoue, Kazutoshi; Shibata, Naoya; Ikuhara, Yuichi

2018-03-27

Clarifying how the atomic structure of interfaces/boundaries in materials affects the magnetic coupling nature across them is of significant academic value and will facilitate the development of state-of-the-art magnetic devices. Here, by combining atomic-resolution transmission electron microscopy, atomistic spin-polarized first-principles calculations, and differential phase contrast imaging, we conduct a systematic investigation of the atomic and electronic structures of individual Fe 3 O 4 twin boundaries (TBs) and determine their concomitant magnetic couplings. We demonstrate that the magnetic coupling across the Fe 3 O 4 TBs can be either antiferromagnetic or ferromagnetic, which directly depends on the TB atomic core structures and resultant electronic structures within a few atomic layers. Revealing the one-to-one correspondence between local atomic structures and magnetic properties of individual grain boundaries will shed light on in-depth understanding of many interesting magnetic behaviors of widely used polycrystalline magnetic materials, which will surely promote the development of advanced magnetic materials and devices.

Magnetic field effects on microwave absorbing materials

NASA Technical Reports Server (NTRS)

Goldberg, Ira; Hollingsworth, Charles S.; Mckinney, Ted M.

1991-01-01

The objective of this program was to gather information to formulate a microwave absorber that can work in the presence of strong constant direct current (DC) magnetic fields. The program was conducted in four steps. The first step was to investigate the electrical and magnetic properties of magnetic and ferrite microwave absorbers in the presence of strong magnetic fields. This included both experimental measurements and a literature survey of properties that may be applicable to finding an appropriate absorbing material. The second step was to identify those material properties that will produce desirable absorptive properties in the presence of intense magnetic fields and determine the range of magnetic field in which the absorbers remain effective. The third step was to establish ferrite absorber designs that will produce low reflection and adequate absorption in the presence of intense inhomogeneous static magnetic fields. The fourth and final step was to prepare and test samples of such magnetic microwave absorbers if such designs seem practical.

Magnetic separation techniques in sample preparation for biological analysis: a review.

PubMed

He, Jincan; Huang, Meiying; Wang, Dongmei; Zhang, Zhuomin; Li, Gongke

2014-12-01

Sample preparation is a fundamental and essential step in almost all the analytical procedures, especially for the analysis of complex samples like biological and environmental samples. In past decades, with advantages of superparamagnetic property, good biocompatibility and high binding capacity, functionalized magnetic materials have been widely applied in various processes of sample preparation for biological analysis. In this paper, the recent advancements of magnetic separation techniques based on magnetic materials in the field of sample preparation for biological analysis were reviewed. The strategy of magnetic separation techniques was summarized. The synthesis, stabilization and bio-functionalization of magnetic nanoparticles were reviewed in detail. Characterization of magnetic materials was also summarized. Moreover, the applications of magnetic separation techniques for the enrichment of protein, nucleic acid, cell, bioactive compound and immobilization of enzyme were described. Finally, the existed problems and possible trends of magnetic separation techniques for biological analysis in the future were proposed. Copyright © 2014 Elsevier B.V. All rights reserved.

Method and apparatus for separating gases based on electrically and magnetically enhanced monolithic carbon fiber composite sorbents

DOEpatents

Judkins, Roddie R.; Burchell, Timothy D.

1999-01-01

A method for separating gases or other fluids involves placing a magnetic field on a monolithic carbon fiber composite sorption material to more preferentially attract certain gases or other fluids to the sorption material to which a magnetic field is applied. This technique may be combined with the known "pressure swing adsorption" technique utilizing the same sorption material.

Fundamentals and advances in magnetic hyperthermia

NASA Astrophysics Data System (ADS)

Périgo, E. A.; Hemery, G.; Sandre, O.; Ortega, D.; Garaio, E.; Plazaola, F.; Teran, F. J.

2015-12-01

Nowadays, magnetic hyperthermia constitutes a complementary approach to cancer treatment. The use of magnetic particles as heating mediators, proposed in the 1950s, provides a novel strategy for improving tumor treatment and, consequently, patient's quality of life. This review reports a broad overview about several aspects of magnetic hyperthermia addressing new perspectives and the progress on relevant features such as the ad hoc preparation of magnetic nanoparticles, physical modeling of magnetic heating, methods to determine the heat dissipation power of magnetic colloids including the development of experimental apparatus and the influence of biological matrices on the heating efficiency.

A Review on Recent Patents and Applications of Inorganic Material Binding Peptides.

PubMed

Thota, Veeranjaneyulu; Perry, Carole C

2017-01-01

Although the popularity of using combinatorial display techniques for recognising unique peptides having high affinity for inorganic (nano) particles has grown rapidly, there are no systematic reviews showcasing current developments or patents on binding peptides specific to these materials. In this review, we summarize and discuss recent progress in patents on material binding peptides specifically exploring inorganic nano surfaces such as metals, metal oxides, minerals, carbonbased materials, polymer based materials, magnetic materials and semiconductors. We consider both the peptide display strategies used and the exploitation of the identified peptides in the generation of advanced nanomaterials. In order to get a clear picture on the number of patents and literature present to date relevant to inorganic material binding biomolecules and their applications, a thorough online search was conducted using national and worldwide databases. The literature search include standard bibliographic databases while patents included EPO Espacenet, WIPO patent scope, USPTO, Google patent search, Patent lens, etc. along with commercial databases such as Derwent and Patbase. Both English and American spellings were included in the searches. The initial number of patents found related to material binders were 981. After reading and excluding irrelevant patents such as organic binding peptides, works published before 2001, repeated patents, documents not in English etc., 51 highly relevant patents published from 2001 onwards were selected and analysed. These patents were further separated into six categories based on their target inorganic material and combinatorial library used. They include relevant patents on metal, metal oxide or combination binding peptides (19), magnetic and semiconductor binding peptides (8), carbon based (3), mineral (5), polymer (8) and other binders (9). Further, how these material specific binders have been used to synthesize simple to complex bio- or nano-materials, mediate the controlled biomineralization process, direct self-assembly and nanofabrication of ordered structures, facilitate the immobilization of functional biomolecules and construct inorganic-inorganic or organic-inorganic nano hybrids are concisely described. From analysis of recent literature and patents, we clearly show that biomimetic material binders are in the vanguard of new design approaches for novel nanomaterials with improved/ controlled physical and chemical properties that have no adverse effect on the structural or functional activities of the nanomaterials themselves. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Diagenetic effects on magnetic minerals in a Holocene lacustrine sediment core from Huguangyan maar lake, southeast China

NASA Astrophysics Data System (ADS)

Wu, Xudong; Wang, Yong; Bian, Liu; Shen, Ji

2016-09-01

Post-depositional reductive diagenesis usually results in partial or entire cleansing of the pristine palaeomagnetic signal, therefore, its intensity is important to be assessed for sediments that are in the purpose of retrieving palaeomagnetic information. Grain size, rock magnetic and geochemical studies on the entire core, along with scanning electron microscope observations and X-ray diffraction analyses for representative samples were carried out on a Holocene sediment core retrieved from the deep water part of Huguangyan maar lake (HGY), southeast China. The pristine magnetic mineral assemblage of the studied core is domianted by superparamagnetic (SP) and stable single domain titanomagnetite, and high coercivity minerals are not detectable. Based on down-core variations of the average grain size (MZ), total organic carbon (TOC), detrital elements (Al, Ti, Fe and Mn) and the concentration and mineralogy of magnetic minerals, the studied core could be divided into three subsections. The uppermost subsection is the least affected by diagenesis, with detrital titanomagnetite as the dominant magnetic mineral. This is owing to low TOC contents, but high detrital input generated by weak Asian summer monsoon intensity during the late Holocene. The intermediate subsection shows down-core progressively enhanced dissolution of detrital titanomagnetite, and concomitant formation of authigenic pyrite and siderite, which indicates down-core progressively enhanced diagenesis generated by down-core progressive increasing TOC content, but decreasing detrital input as the result of down-core progressively strengthened Asian summer monsoon intensity. The pristine magnetic mineral assemblage has been profoundly modified in the lowermost subsection. At certain positions of the lowermost subsection, detrital titanomagnetite has been even completely dissolved via diagenesis, giving place to authigenic pyrite and siderite. High TOC content, but low detrital input generated from strong Asian summer monsoon intensity during the early Holocene are accountable for intensive diagenesis in the lowermost subsection. Complete erasing of detrital magnetic input signal at certain positions of the lowermost subsection, and considerable formation of authigenic siderite indicate that palaeomagnetic records of the studied core have been significantly compromised. The studied core has relatively higher TOC content, lower detrital matter content, calmer sedimentary environments, and less DO available at its water-sediment interface than the cores retrieved at relatively shallower water depths, which all contribute to its relatively stronger diagenesis. Progressive thickening of the upper two subsections with increasing water depth is owing to progressive increase in sedimentation rate with increasing water depth, which is the key factor in determining the thickness of each diagenetic subsection of cores from HGY. It would be better that lake sediments for palaeomagnetic investigations collected at a water depth shallower than the depth of its thermocline.

Wireless Chemical Sensor and Sensing Method for Use Therewith

NASA Technical Reports Server (NTRS)

Oglesby, Donald M. (Inventor); Taylor, Bryant D. (Inventor); Woodard, Stanley E. (Inventor)

2016-01-01

A wireless chemical sensor includes an electrical conductor and a material separated therefrom by an electric insulator. The electrical conductor is an unconnected open-circuit shaped for storage of an electric field and a magnetic field. In the presence of a time-varying magnetic field, the first electrical conductor resonates to generate harmonic electric and magnetic field responses. The material is positioned at a location lying within at least one of the electric and magnetic field responses so-generated. The material changes in electrical conductivity in the presence of a chemical-of-interest.

Wireless Chemical Sensor and Sensing Method for Use Therewith

NASA Technical Reports Server (NTRS)

Woodard, Stanley E. (Inventor); Oglesby, Donald M. (Inventor); Taylor, Bryant Douglas (Inventor)

2014-01-01

A wireless chemical sensor includes an electrical conductor and a material separated therefrom by an electric insulator. The electrical conductor is an unconnected open-circuit shaped for storage of an electric field and a magnetic field. In the presence of a time-varying magnetic field, the first electrical conductor resonates to generate harmonic electric and magnetic field responses. The material is positioned at a location lying within at least one of the electric and magnetic field responses so-generated. The material changes in electrical conductivity in the presence of a chemical-of-interest.

Wireless Chemical Sensing Method

NASA Technical Reports Server (NTRS)

Taylor, Bryant D. (Inventor); Woodard, Stanley E. (Inventor); Oglesby, Donald M. (Inventor)

2017-01-01

A wireless chemical sensor includes an electrical conductor and a material separated therefrom by an electric insulator. The electrical conductor is an unconnected open-circuit shaped for storage of an electric field and a magnetic field. In the presence of a time-varying magnetic field, the first electrical conductor resonates to generate harmonic electric and magnetic field responses. The material is positioned at a location lying within at least one of the electric and magnetic field responses so-generated. The material changes in electrical conductivity in the presence of a chemical-of-interest.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evans, III, Boyd Mccutchen; Kisner, Roger A.; Ludtka, Gail Mackiewicz

A method of making a single crystal comprises heating a material comprising magnetic anisotropy to a temperature T sufficient to form a melt of the material. A magnetic field of at least about 1 Tesla is applied to the melt at the temperature T, where a magnetic free energy difference .DELTA.G.sub.m between different crystallographic axes is greater than a thermal energy kT. While applying the magnetic field, the melt is cooled at a rate of about 30.degree. C./min or higher, and the melt solidifies to form a single crystal of the material.

A Cryogenic Magnetostrictive Actuator Using a Persistent High Temperature Superconducting Magnet. Part 1; Concept and Design

NASA Technical Reports Server (NTRS)

Horner, Garnett; Bromberg, Leslie; Teter, J. P.

2000-01-01

Cryogenic magnetostrictive materials, such as rare earth zinc crystals, offer high strains and high forces with minimally applied magnetic fields, making the material ideally suited for deformable optics applications. For cryogenic temperature applications the use of superconducting magnets offer the possibility of a persistent mode of operation, i.e., the magnetostrictive material will maintain a strain field without power. High temperature superconductors (HTS) are attractive options if the temperature of operation is higher than 10 degrees Kelvin (K) and below 77 K. However, HTS wires have constraints that limit the minimum radius of winding, and even if good wires can be produced, the technology for joining superconducting wires does not exist. In this paper, the design and capabilities of a rare earth zinc magnetostrictive actuator using bulk HTS is described. Bulk superconductors can be fabricated in the sizes required with excellent superconducting properties. Equivalent permanent magnets, made with this inexpensive material, are persistent, do not require a persistent switch as in HTS wires, and can be made very small. These devices are charged using a technique which is similar to the one used for charging permanent magnets, e.g., by driving them into saturation. A small normal conducting coil can be used for charging or discharging. Because of the magnetic field capability of the superconductor material, a very small amount of superconducting magnet material is needed to actuate the rare earth zinc. In this paper, several designs of actuators using YBCO and BSCCO 2212 superconducting materials are presented. Designs that include magnetic shielding to prevent interaction between adjacent actuators will also be described. Preliminary experimental results and comparison with theory for BSCCO 2212 with a magnetostrictive element will be discussed.

Dynamic response of a sensor element made of magnetic hybrid elastomer with controllable properties

NASA Astrophysics Data System (ADS)

Becker, T. I.; Zimmermann, K.; Borin, D. Yu.; Stepanov, G. V.; Storozhenko, P. A.

2018-03-01

Smart materials like magnetic hybrid elastomers (MHEs) are based on an elastic composite with a complex hybrid filler of magnetically hard and soft particles. Due to their unique magnetic field depending characteristics, these elastomers offer great potential for designing sensor systems with a complex adaptive behaviour and operating sensitivity. The present paper deals with investigations of the material properties and motion behaviour displayed by synthesised MHE beams in the presence of a uniform magnetic field. The distribution and structure formation of the magnetic components inside the elastic matrix depending on the manufacturing conditions are examined. The specific magnetic features of the MHE material during the magnetising process are revealed. Experimental investigations of the in-plane free vibrational behaviour displayed by the MHE beams with the fixed-free end conditions are performed for various magnitudes of an imposed uniform magnetic field. For the samples pre-magnetised along the length axis, it is demonstrated that the deflection of the beam can be identified unambiguously by magnetic field distortion measurements. It is shown that the material properties of the vibrating MHE element can be specifically adjusted by means of an external magnetic field control. The dependence of the first eigenfrequency of free bending vibrations of the MHE beams on the strength of an imposed uniform magnetic field is obtained. The results are aimed to assess the potential of MHEs to design acceleration sensor systems with an adaptive magnetically controllable sensitivity range.

Paramagnetic and Diamagnetic Materials

ERIC Educational Resources Information Center

Thompson, Frank

2011-01-01

Paramagnetic and diamagnetic materials are now generally known as the "Cinderella" materials of the magnetic world. However, susceptibility measurements made on these materials in the past have revealed many details about the molecular bonding and the atomic structure of the so-called "transition" elements. Indeed, the magnetic moment of neodymium…

Composite Materials with Magnetically Aligned Carbon Nanoparticles and Methods of Preparation

NASA Technical Reports Server (NTRS)

Salem, David R. (Inventor); Hong, Haiping (Inventor); Peterson, G.P. (Bud) (Inventor)

2018-01-01

The present invention relates to magnetically aligned carbon nanoparticle composites and methods of preparing the same. The composites comprise carbon nanoparticles, host material, magnetically sensitive nanoparticles and surfactant. The composites may have enhanced mechanical, thermal, and/or electrical properties.

Feasibility of low-cost magnetic rail designs by integrating ferrite magnets and NdFeB magnets for HTS Maglev systems

NASA Astrophysics Data System (ADS)

Sun, R. X.; Deng, Z. G.; Gou, Y. F.; Li, Y. J.; Zheng, J.; Wang, S. Y.; Wang, J. S.

2015-09-01

Permanent magnet guideway (PMG) is an indispensable part of high temperature superconducting (HTS) Maglev systems. Present PMGs are made of NdFeB magnets with excellent performance and cost much. As another permanent magnet material, the ferrite magnet is weak at magnetic energy product and coercive force, but inexpensive. So, it is a possible way to integrate the ferrite and NdFeB magnets for cutting down the cost of present PMGs. In the paper, the equivalent on magnetic field intensity between ferrite magnets and NdFeB magnets was evaluated by finite element simulation. According to the calculation results, the magnetic field of the PMG integrating ferrite magnets and NdFeB magnets can be increased remarkably comparing with the pure ferrite PMG. It indicates that low-cost PMG designs by integrating the two permanent magnet materials are feasible for the practical HTS Maglev system.

Element of an inductive coupler

DOEpatents

Hall, David R.; Fox, Joe

2006-08-15

An element for an inductive coupler in a downhole component comprises magnetically conductive material, which is disposed in a recess in annular housing. The magnetically conductive material forms a generally circular trough. The circular trough comprises an outer generally U-shaped surface, an inner generally U-shaped surface, and two generally planar surfaces joining the inner and outer surfaces. The element further comprises pressure relief grooves in at least one of the surfaces of the circular trough. The pressure relief grooves may be scored lines. Preferably the pressure relief grooves are parallel to the magnetic field generated by the magnetically conductive material. The magnetically conductive material is selected from the group consisting of soft iron, ferrite, a nickel iron alloy, a silicon iron alloy, a cobalt iron alloy, and a mu-metal. Preferably, the annular housing is a metal ring.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Francis

A team led by GE Global Research developed new magnetic refrigerant materials needed to enhance the commercialization potential of residential appliances such as refrigerators and air conditioners based on the magnetocaloric effect (a nonvapor compression cooling cycle). The new magnetic refrigerant materials have potentially better performance at lower cost than existing materials, increasing technology readiness level. The performance target of the new magnetocaloric material was to reduce the magnetic field needed to achieve 4 °C adiabatic temperature change from 1.5 Tesla to 0.75 Tesla. Such a reduction in field minimizes the cost of the magnet assembly needed for a magneticmore » refrigerator. Such a reduction in magnet assembly cost is crucial to achieving commercialization of magnetic refrigerator technology. This project was organized as an iterative alloy development effort with a parallel material modeling task being performed at George Washington University. Four families of novel magnetocaloric alloys were identified, screened, and assessed for their performance potential in a magnetic refrigeration cycle. Compositions from three of the alloy families were manufactured into regenerator components. At the beginning of the project a previously studied magnetocaloric alloy was selected for manufacturing into the first regenerator component. Each of the regenerators was tested in magnetic refrigerator prototypes at a subcontractor at at GE Appliances. The property targets for operating temperature range, operating temperature control, magnetic field sensitivity, and corrosion resistance were met. The targets for adiabatic temperature change and thermal hysteresis were not met. The high thermal hysteresis also prevented the regenerator components from displaying measurable cooling power when tested in prototype magnetic refrigerators. Magnetic refrigerant alloy compositions that were predicted to have low hysteresis were not attainable with conventional alloy processing methods. Preliminary experiments with rapid solidification methods showed a path towards attaining low hysteresis compositions should this alloy development effort be continued.« less

Method and Apparatus of Implementing a Magnetic Shield Flux Sweeper

NASA Technical Reports Server (NTRS)

Sadleir, John E. (Inventor)

2018-01-01

The present invention relates to a method and apparatus of protecting magnetically sensitive devices with a shield, including: a non-superconducting metal or lower transition temperature (T.sub.c) material compared to a higher transition temperature material, disposed in a magnetic field; means for creating a spatially varying order parameter's |.PSI.(r,T)|.sup.2 in a non-superconducting metal or a lower transition temperature material; wherein a spatially varying order parameter is created by a proximity effect, such that the non-superconducting metal or the lower transition temperature material becomes superconductive as a temperature is lowered, creating a flux-free Meissner state at a center thereof, in order to sweep magnetic flux lines to the periphery.

Sub-surface structure of La Soufrière of Guadeloupe lava dome deduced from a ground-based magnetic survey

NASA Astrophysics Data System (ADS)

Bouligand, Claire; Coutant, Olivier; Glen, Jonathan M. G.

2016-07-01

In this study, we present the analysis and interpretation of a new ground magnetic survey acquired at the Soufrière volcano on Guadeloupe Island. Observed short-wavelength magnetic anomalies are compared to those predicted assuming a constant magnetization within the sub-surface. The good correlation between modeled and observed data over the summit of the dome indicates that the shallow sub-surface displays relatively constant and high magnetization intensity. In contrast, the poor correlation at the base of the dome suggests that the underlying material is non- to weakly-magnetic, consistent with what is expected for a talus comprised of randomly oriented and highly altered and weathered boulders. The new survey also reveals a dipole anomaly that is not accounted for by a constant magnetization in the sub-surface and suggests the existence of material with decreased magnetization beneath the Soufrière lava dome. We construct simple models to constrain its dimensions and propose that this body corresponds to hydrothermally altered material within and below the dome. The very large inferred volume for such material may have implications on the stability of the dome.

Costs, Substitution, and Material Use: The Case of Rare Earth Magnets.

PubMed

Smith, Braeton J; Eggert, Roderick G

2018-03-20

Environmental technologies depend on raw materials, some of which are subject to volatile costs and availability concerns. One way to address these concerns is through substitution, of which there are many types. An important form of substitution in the short term is adopting an alternative production process, yielding a material with the same functional properties with less material input. In effect, technology substitutes for material. This study elucidates the role increased and uncertain material costs play in inducing different substitution types in the short to medium term. Specifically, this paper uses an expert survey to determine the relative importance of eight specific industry responses taken by magnet and wind turbine manufacturers in response to the 2010/2011 rare-earth price spike through 2016. Statistical tests show adopting an existing production process for magnets was the most important response, followed by cost passthrough, using an alternate magnet grade in a redesigned generator system, and using alternate systems altogether. The paper also provides specific findings for the magnet and wind turbine industries with respect to each substitution type.

Extreme Material Physical Properties and Measurements above 100 tesla

NASA Astrophysics Data System (ADS)

Mielke, Charles

2011-03-01

The National High Magnetic Field Laboratory (NHMFL) Pulsed Field Facility (PFF) at Los Alamos National Laboratory (LANL) offers extreme environments of ultra high magnetic fields above 100 tesla by use of the Single Turn method as well as fields approaching 100 tesla with more complex methods. The challenge of metrology in the extreme magnetic field generating devices is complicated by the millions of amperes of current and tens of thousands of volts that are required to deliver the pulsed power needed for field generation. Methods of detecting physical properties of materials are essential parts of the science that seeks to understand and eventually control the fundamental functionality of materials in extreme environments. De-coupling the signal of the sample from the electro-magnetic interference associated with the magnet system is required to make these state-of-the-art magnetic fields useful to scientists studying materials in high magnetic fields. The cutting edge methods that are being used as well as methods in development will be presented with recent results in Graphene and High-Tc superconductors along with the methods and challenges. National Science Foundation DMR-Award 0654118.

Magnetic Nanoparticle Drug Carriers and their Study by Quadrupole Magnetic Field-Flow Fractionation

PubMed Central

Williams, P. Stephen; Carpino, Francesca; Zborowski, Maciej

2009-01-01

Magnetic nanoparticle drug carriers continue to attract considerable interest for drug targeting in the treatment of cancers and other pathological conditions. The efficient delivery of therapeutic levels of drug to a target site while limiting nonspecific, systemic toxicity requires optimization of the drug delivery materials, the applied magnetic field, and the treatment protocol. The history and current state of magnetic drug targeting is reviewed. While initial studies involved micron-sized and larger carriers, and work with these microcarriers continues, it is the sub-micron carriers or nanocarriers that are of increasing interest. An aspect of magnetic drug targeting using nanoparticle carriers that has not been considered is then addressed. This aspect involves the variation in the magnetic properties of the nanocarriers. Quadrupole magnetic field-flow fractionation (QMgFFF) is a relatively new technique for characterizing magnetic nanoparticles. It is unique in its capability of determining the distribution in magnetic properties of a nanoparticle sample in suspension. The development and current state of this technique is also reviewed. Magnetic nanoparticle drug carriers have been found by QMgFFF analysis to be highly polydisperse in their magnetic properties, and the strength of response of the particles to magnetic field gradients is predicted to vary by orders of magnitude. It is expected that the least magnetic fraction of a formulation will contribute the most to systemic toxicity, and the depletion of this fraction will result in a more effective drug carrying material. A material that has a reduced systemic toxicity will allow higher doses of cytotoxic drugs to be delivered to the tumor with reduced side effects. Preliminary experiments involving a novel method of refining a magnetic nanoparticle drug carrier to achieve this result are described. QMgFFF is used to characterize the refined and unrefined material. PMID:19591456

A coordination polymer based magnetic adsorbent material for hemoglobin isolation from human whole blood, highly selective and recoverable

NASA Astrophysics Data System (ADS)

Zhang, Xiaoxing; Tan, Jipeng; Xu, Xinxin; Shi, Fanian; Li, Guanglu; Yang, Yiqiao

2017-09-01

A composite material has been obtained successfully through the loading of nanoscale coordination polymer on magnetic Fe3O4@SiO2 core-shell particle. In this composite material, coordination polymer nanoparticles distribute uniformly on Fe3O4@SiO2 and these two components are "tied" together firmly with chemical bonds. Adsorption experiments suggest this composite material exhibits very excellent selectivity to hemoglobin. But under the same condition, its adsorption to bovine serum albumin can almost be ignored. This selectivity can be attributed to the existence of hydrophobic interactions between coordination polymer nanoparticle and hemoglobin. For composite material, the hemoglobin adsorption process follows Langmuir model perfectly with high speed. The adsorbed hemoglobin can be eluted easily by sodium dodecyl sulfate stripping reagent with structure and biological activity of hemoglobin keeps well. The composite material was also employed to separate hemoglobin from human whole blood, which receives a very satisfactory result. Furthermore, magnetic measurement reveals ferromagnetic character of this composite material with magnetization saturation 3.56 emu g-1 and this guarantees its excellent magnetic separation performance from the treated solution.

Energy transport velocity in bidispersed magnetic colloids.

PubMed

Bhatt, Hem; Patel, Rajesh; Mehta, R V

2012-07-01

Study of energy transport velocity of light is an effective background for slow, fast, and diffuse light and exhibits the photonic property of the material. We report a theoretical analysis of magnetic field dependent resonant behavior in forward-backward anisotropy factor, light diffusion constant, and energy transport velocity for bidispersed magnetic colloids. A bidispersed magnetic colloid is composed of micrometer size magnetic spheres dispersed in a magnetic nanofluid consisting of magnetic nanoparticles in a nonmagnetic liquid carrier. Magnetic Mie resonances and reduction in energy transport velocity accounts for the possible delay (longer dwell time) by field dependent resonant light transport. This resonant behavior of light in bidispersed magnetic colloids suggests a novel magnetophotonic material.

Magnetic switch for reactor control rod. [LMFBR

DOEpatents

Germer, J.H.

1982-09-30

A magnetic reed switch assembly is described for activating an electromagnetic grapple utilized to hold a control rod in position above a reactor core. In normal operation the magnetic field of a permanent magnet is short-circuited by a magnetic shunt, diverting the magnetic field away from the reed switch. The magnetic shunt is made of a material having a Curie-point at the desired release temperature. Above that temperature the material loses its ferromagnetic properties, and the magnetic path is diverted to the reed switch which closes and short-circuits the control circuit for the control rod electro-magnetic grapple which allows the control rod to drop into the reactor core for controlling the reactivity of the core.

Magnetic domain wall gratings for magnetization reversal tuning and confined dynamic mode localization.

PubMed

Trützschler, Julia; Sentosun, Kadir; Mozooni, Babak; Mattheis, Roland; McCord, Jeffrey

2016-08-04

High density magnetic domain wall gratings are imprinted in ferromagnetic-antiferromagnetic thin films by local ion irradiation by which alternating head-to-tail-to-head-to-tail and head-to-head-to-tail-to-tail spatially overlapping domain wall networks are formed. Unique magnetic domain processes result from the interaction of anchored domain walls. Non-linear magnetization response is introduced by the laterally distributed magnetic anisotropy phases. The locally varying magnetic charge distribution gives rise to localized and guided magnetization spin-wave modes directly constrained by the narrow domain wall cores. The exchange coupled multiphase material structure leads to unprecedented static and locally modified dynamic magnetic material properties.

Magnetic domain wall gratings for magnetization reversal tuning and confined dynamic mode localization

NASA Astrophysics Data System (ADS)

Trützschler, Julia; Sentosun, Kadir; Mozooni, Babak; Mattheis, Roland; McCord, Jeffrey

2016-08-01

High density magnetic domain wall gratings are imprinted in ferromagnetic-antiferromagnetic thin films by local ion irradiation by which alternating head-to-tail-to-head-to-tail and head-to-head-to-tail-to-tail spatially overlapping domain wall networks are formed. Unique magnetic domain processes result from the interaction of anchored domain walls. Non-linear magnetization response is introduced by the laterally distributed magnetic anisotropy phases. The locally varying magnetic charge distribution gives rise to localized and guided magnetization spin-wave modes directly constrained by the narrow domain wall cores. The exchange coupled multiphase material structure leads to unprecedented static and locally modified dynamic magnetic material properties.

Breakthrough and future: nanoscale controls of compositions, morphologies, and mesochannel orientations toward advanced mesoporous materials.

PubMed

Yamauchi, Yusuke; Suzuki, Norihiro; Radhakrishnan, Logudurai; Wang, Liang

2009-01-01

Currently, ordered mesoporous materials prepared through the self-assembly of surfactants have attracted growing interests owing to their special properties, including uniform mesopores and a high specific surface area. Here we focus on fine controls of compositions, morphologies, mesochannel orientations which are important factors for design of mesoporous materials with new functionalities. This Review describes our recent progress toward advanced mesoporous materials. Mesoporous materials now include a variety of inorganic-based materials, for example, transition-metal oxides, carbons, inorganic-organic hybrid materials, polymers, and even metals. Mesoporous metals with metallic frameworks can be produced by using surfactant-based synthesis with electrochemical methods. Owing to their metallic frameworks, mesoporous metals with high electroconductivity and high surface areas hold promise for a wide range of potential applications, such as electronic devices, magnetic recording media, and metal catalysts. Fabrication of mesoporous materials with controllable morphologies is also one of the main subjects in this rapidly developing research field. Mesoporous materials in the form of films, spheres, fibers, and tubes have been obtained by various synthetic processes such as evaporation-mediated direct templating (EDIT), spray-dried techniques, and collaboration with hard-templates such as porous anodic alumina and polymer membranes. Furthermore, we have developed several approaches for orientation controls of 1D mesochannels. The macroscopic-scale controls of mesochannels are important for innovative applications such as molecular-scale devices and electrodes with enhanced diffusions of guest species. Copyright 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

Review of magnetic refrigeration system as alternative to conventional refrigeration system

NASA Astrophysics Data System (ADS)

Mezaal, N. A.; Osintsev, K. V.; Zhirgalova, T. B.

2017-10-01

The refrigeration system is one of the most important systems in industry. Developers are constantly seeking for how to avoid the damage to the environment. Magnetic refrigeration is an emerging, environment-friendly technology based on a magnetic solid that acts as a refrigerant by magneto-caloric effect (MCE). In the case of ferromagnetic materials, MCE warms as the magnetic moments of the atom are aligned by the application of a magnetic field. There are two types of magnetic phase changes that may occur at the Curie point: first order magnetic transition (FOMT) and second order magnetic transition (SOMT). The reference cycle for magnetic refrigeration is AMR (Active Magnetic Regenerative cycle), where the magnetic material matrix works both as a refrigerating medium and as a heat regenerating medium, while the fluid flowing in the porous matrix works as a heat transfer medium. Regeneration can be accomplished by blowing a heat transfer fluid in a reciprocating fashion through the regenerator made of magnetocaloric material that is alternately magnetized and demagnetized. Many magnetic refrigeration prototypes with different designs and software models have been built in different parts of the world. In this paper, the authors try to shed light on the magnetic refrigeration and show its effectiveness compared with conventional refrigeration methods.

An early start to STEM education among year 1 primary students through project-based inquiry learning in the context of a magnet

NASA Astrophysics Data System (ADS)

Safiee, N.; Jusoh, Z. M.; Noor, A. M. H. M.; Tek, O. E.; Salleh, S. M.

2018-01-01

For the needs of the 21st century, the Government of Malaysia has conceptualized the Malaysia Education Blueprint 2013-2025 which embodies 11 strategic and operational shifts. In Shift 1, it is emphasized that the quality of Science, Technology, Engineering, and Mathematics (STEM) Education will be enhanced. This study employed the mixed-method approach using the “one-group pre-test and post-test design”. Accordingly, this paper describes the pedagogical practice of Project-based Inquiry Learning (PIL) which promotes STEM Education among Year 1 students in the move to progress in tandem with Shift 1. Specifically, using the context of a magnet which has been stipulated in the Primary School Standard Curriculum, Year 1 students experienced the STEM Education through the STEM Pedagogy in which they raised questions upon the presentation of a relevant stimulus (Inquiry Phase), explored the ways in which a train carriage or coach could be assembled by means of recycled materials and magnets (Exploration Phase), designed a train carriage (Design Phase), and ultimately reflected on their inventions (Reflection Phase). The cognitive and affective impacts through the use of this Project-based Inquiry Learning are presented. Implications for the teaching and learning of science are discussed within the context of STEM Education.

Operation of Lanzhou all permanent electron cyclotron resonance ion source No. 2 on 320 kV platform with highly charged ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, W., E-mail: luwang@impcas.ac.cn; University of Chinese Academy of Sciences, Beijing 100049; Li, J. Y.

2014-02-15

The 320 kV platform for multi-discipline research with highly charged ions is a heavy ion beam acceleration instrument developed by Institute of Modern Physics, which is dedicated to basic scientific researches such as plasma, atom, material physics, and astrophysics, etc. The platform has delivered ion beams of 400 species for 36 000 h. The average operation time is around 5000 h/year. With the beams provided by the platform, lots of outstanding progresses were made in various research fields. The ion source of the platform is an all-permanent magnet electron cyclotron resonance ion source, LAPECR2 (Lanzhou All Permanent ECR ion source No.more » 2). The maximum axial magnetic fields are 1.28 T at injection and 1.07 T at extraction, and the radial magnetic field is up to 1.21 T at the inner wall of the plasma chamber. The ion source is capable to produce low, medium, and high charge state gaseous and metallic ion beams, such as H{sup +}, {sup 40}Ar{sup 8+}, {sup 129}Xe{sup 30+}, {sup 209}Bi{sup 33+}, etc. This paper will present the latest result of LAPECR2 and the routine operation status for the high voltage platform.« less

On interstellar light polarization by diamagnetic silicate and carbon dust in the infrared

NASA Astrophysics Data System (ADS)

Papoular, R.

2018-04-01

The motion of diamagnetic dust particles in interstellar magnetic fields is studied numerically with several different sets of parameters. Two types of behaviour are observed, depending on the value of the critical number R, which is a function of the grain inertia, the magnetic susceptibility of the material and of the strength of rotation braking. If R ≤ 10, the grain ends up in a static state and perfectly aligned with the magnetic field, after a few braking times. If not, it goes on precessing and nutating about the field vector for a much longer time. Usual parameters are such that the first situation can hardly be observed. Fortunately, in the second and more likely situation, there remains a persistent partial alignment that is far from negligible, although it decreases as the field decreases and as R increases. The solution of the complete equations of motion of grains in a field helps understanding the details of this behaviour. One particular case of an ellipsoidal forsterite silicate grain is studied in detail and shown to polarize light in agreement with astronomical measurements of absolute polarization in the infrared. Phonons are shown to contribute to the progressive flattening of extinction and polarization towards long wavelengths. The measured dielectric properties of forsterite qualitatively fit the Serkowski peak in the visible.

Composite Materials with Magnetically Aligned Carbon Nanoparticles Having Enhanced Electrical Properties and Methods of Preparation

NASA Technical Reports Server (NTRS)

Peterson, G.P. (Bud) (Inventor); Hong, Haiping (Inventor); Salem, David R. (Inventor)

2016-01-01

Magnetically aligned carbon nanoparticle composites have enhanced electrical properties. The composites comprise carbon nanoparticles, a host material, magnetically sensitive nanoparticles and a surfactant. In addition to enhanced electrical properties, the composites can have enhanced mechanical and thermal properties.

Magnetic phase investigations on fluorine (F) doped LiFePO4

NASA Astrophysics Data System (ADS)

Radhamani, A. V.

2018-03-01

LiFePO4 (LFP) is a very promising cathode material for Li-ion batteries due to its high thermal stability, less toxicity and high theoretical capacity (170 mAh g-1). Anion doping, especially fluorine (F) at the oxygen site is one way to improve the low electronic conductivity of the material. In this line, fluorine doped LFP was prepared at different fluorine concentrations (1 to 40 mol%) to study the structural, spectroscopic and magnetic properties in view of the material property optimization for battery applications. The investigation of the magnetic properties was found to be successful for the determination of small amounts of magnetic impurities which were not noticeably observed from structural characterizations. Determination of conducting magnetic impurities has its own relevance in the current scenario of Li-ion based battery applications. Systematic characterization studies along with the implications of magnetic phases on the material activity of fluorine doped LiFePO4 nanoparticles will be discussed in detail.

Modeling and Characterization of the Magnetocaloric Effect in Ni2MnGa Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nicholson, Don M; Odbadrakh, Khorgolkhuu; Rios, Orlando

2012-01-01

Magnetic shape memory alloys have great promise as magneto-caloric effect refrigerant materials due to their combined magnetic and structural transitions. Computational and experimental research is reported on the Ni2MnGa material system. The magnetic states of this system have been explored using the Wang-Landau statistical approach in conjunction with the Locally Self-consistent Multiple-Scattering (LSMS) method to explore the magnetic states responsible for the magnet-caloric effect in this material. The effects of alloying agents on the transition temperatures of the Ni2MnGa alloy were investigated using differential scanning calorimetry (DSC) and superconducting quantum interference device (SQUID). Neutron scattering experiments were performed to observemore » the structural and magnetic phase transformations at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) on alloys of Ni-Mn-Ga and Ni-Mn-Ga-Cu-Fe. Data from the observations are discussed in comparison with the computational studies.« less

The role of early magnetic resonance imaging in predicting survival on bevacizumab for recurrent glioblastoma: Results from a prospective clinical trial (CABARET).

PubMed

Field, Kathryn M; Phal, Pramit M; Fitt, Greg; Goh, Christine; Nowak, Anna K; Rosenthal, Mark A; Simes, John; Barnes, Elizabeth H; Sawkins, Kate; Cher, Lawrence M; Hovey, Elizabeth J; Wheeler, Helen

2017-09-15

Bevacizumab has been associated with prolonged progression-free survival for patients with recurrent glioblastoma; however, not all derive a benefit. An early indicator of efficacy or futility may allow early discontinuation for nonresponders. This study prospectively assessed the role of early magnetic resonance imaging (eMRI) and its correlation with subsequent routine magnetic resonance imaging (MRI) results and survival. Patients were part of a randomized phase 2 clinical trial (CABARET) comparing bevacizumab with bevacizumab plus carboplatin for recurrent glioblastoma. eMRI was conducted after 4 weeks in the trial (after 2 treatments with bevacizumab [10 mg/kg every 2 weeks]). The results were compared with the results of the subsequent 8-week MRI standard. For 119 of 122 patients, eMRI was available, and 111 had subsequent MRI for comparison. Thirty-six (30%) had an early radiological response, and 17 (14%) had progressive disease. The concordance between eMRI and 8-week MRI was moderate (κ = 0.56), with most providing the same result (n = 79 [71%]). There was strong evidence that progression-free survival and overall survival were predicted by the eMRI response (both P values < .001). The median survival was 8.6 months for an eMRI response, 6.6 months for stable disease, and 3.7 months for progressive disease; the hazard ratio (progressive disease vs stable disease) was 3.4 (95% confidence interval, 1.9-6.0). Landmark analyses showed that eMRI progression was a strong predictor of mortality independent of other potential baseline predictors. In this study, early progression on MRI appears to be a robust marker of a poor prognosis for patients on bevacizumab. Cancer 2017;123:3576-82. © 2017 American Cancer Society. © 2017 American Cancer Society.

Magnetic latch trigger for inherent shutdown assembly

DOEpatents

Sowa, Edmund S.

1976-01-01

An inherent shutdown assembly for a nuclear reactor is provided. A neutron absorber is held ready to be inserted into the reactor core by a magnetic latch. The latch includes a magnet whose lines of force are linked by a yoke of material whose Curie point is at the critical temperature of the reactor at which the neutron absorber is to be inserted into the reactor core. The yoke is in contact with the core coolant or fissionable material so that when the coolant or the fissionable material increase in temperature above the Curie point the yoke loses its magnetic susceptibility and the magnetic link is broken, thereby causing the absorber to be released into the reactor core.

Flow-controlled magnetic particle manipulation

DOEpatents

Grate, Jay W [West Richland, WA; Bruckner-Lea, Cynthia J [Richland, WA; Holman, David A [Las Vegas, NV

2011-02-22

Inventive methods and apparatus are useful for collecting magnetic materials in one or more magnetic fields and resuspending the particles into a dispersion medium, and optionally repeating collection/resuspension one or more times in the same or a different medium, by controlling the direction and rate of fluid flow through a fluid flow path. The methods provide for contacting derivatized particles with test samples and reagents, removal of excess reagent, washing of magnetic material, and resuspension for analysis, among other uses. The methods are applicable to a wide variety of chemical and biological materials that are susceptible to magnetic labeling, including, for example, cells, viruses, oligonucleotides, proteins, hormones, receptor-ligand complexes, environmental contaminants and the like.

Method and apparatus for separating gases based on electrically and magnetically enhanced monolithic carbon fiber composite sorbents

DOEpatents

Judkins, R.R.; Burchell, T.D.

1999-07-20

A method for separating gases or other fluids involves placing a magnetic field on a monolithic carbon fiber composite sorption material to more preferentially attract certain gases or other fluids to the sorption material to which a magnetic field is applied. This technique may be combined with the known pressure swing adsorption'' technique utilizing the same sorption material. 1 fig.

Electrochemical Solution Growth of Magnetic Nitrides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Monson, Todd C.; Pearce, Charles

Magnetic nitrides, if manufactured in bulk form, would provide designers of transformers and inductors with a new class of better performing and affordable soft magnetic materials. According to experimental results from thin films and/or theoretical calculations, magnetic nitrides would have magnetic moments well in excess of current state of the art soft magnets. Furthermore, magnetic nitrides would have higher resistivities than current transformer core materials and therefore not require the use of laminates of inactive material to limit eddy current losses. However, almost all of the magnetic nitrides have been elusive except in difficult to reproduce thin films or asmore » inclusions in another material. Now, through its ability to reduce atmospheric nitrogen, the electrochemical solution growth (ESG) technique can bring highly sought after (and previously inaccessible) new magnetic nitrides into existence in bulk form. This method utilizes a molten salt as a solvent to solubilize metal cations and nitrogen ions produced electrochemically and form nitrogen compounds. Unlike other growth methods, the scalable ESG process can sustain high growth rates (~mm/hr) even under reasonable operating conditions (atmospheric pressure and 500 °C). Ultimately, this translates into a high throughput, low cost, manufacturing process. The ESG process has already been used successfully to grow high quality GaN. Below, the experimental results of an exploratory express LDRD project to access the viability of the ESG technique to grow magnetic nitrides will be presented.« less

Fluorescent and Magnetic Mesoporous Hybrid Material: A Chemical and Biological Nanosensor for Hg2+ Ions

PubMed Central

Suresh, Moorthy; Anand, Chokkalingam; Frith, Jessica E.; Dhawale, Dattatray S.; Subramaniam, Vishnu P.; Strounina, Ekaterina; Sathish, Clastinrusselraj I.; Yamaura, Kazunari; Cooper-White, Justin J.; Vinu, Ajayan

2016-01-01

We introduce “sense, track and separate” approach for the removal of Hg2+ ion from aqueous media using highly ordered and magnetic mesoporous ferrosilicate nanocages functionalised with rhodamine fluorophore derivative. These functionalised materials offer both fluorescent and magnetic properties in a single system which help not only to selectively sense the Hg2+ ions with a high precision but also adsorb and separate a significant amount of Hg2+ ion in aqueous media. We demonstrate that the magnetic affinity of these materials, generated from the ultrafine γ-Fe2O3 nanoparticles present inside the nanochannels of the support, can efficiently be used as a fluorescent tag to sense the Hg2+ ions present in NIH3T3 fibroblasts live cells and to track the movement of the cells by external magnetic field monitored using confocal fluorescence microscopy. This simple approach of introducing multiple functions in the magnetic mesoporous materials raise the prospect of creating new advanced functional materials by fusing organic, inorganic and biomolecules to create advanced hybrid nanoporous materials which have a potential use not only for sensing and the separation of toxic metal ions but also for cell tracking in bio-separation and the drug delivery. PMID:26911660

Dental materials and magnetic resonance imaging.

PubMed

Hubálková, Hana; Hora, Karel; Seidl, Zdenek; Krásenský, Jan

2002-09-01

The objective of this investigation was to evaluate the reaction of selected dental materials in the magnetic field of a magnetic resonance imaging device to determine a possible health risk. The following dental materials were tested in vitro during magnetic resonance imaging: 15 dental alloys, four dental implants, one surgical splint and two wires for fixation of maxillofacial fractures. Possible artefacts (corresponding with magnetic properties), heating and force effects were tested. Results concerning movement and heating were in agreement with the literature. The artefacts seen were significant: for the surgical splint, a spherical artefact with a diameter of 55 mm; for the wires, up to 22 mm; and for the dental blade implant, an artefact of 28 x 20 mm. The results of our tests of selected dental appliances indicate that their presence in the human organism is safe for patients undergoing magnetic resonance imaging procedures. The presence of artefacts can substantially influence the magnetic resonance imaging results.

DOE-EPSCoR. Exchange interactions in epitaxial intermetallic layered systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

LeClair, Patrick R.; Gary, Mankey J.

2015-05-25

The goal of this research is to develop a fundamental understanding of the exchange interactions in epitaxial intermetallic alloy thin films and multilayers, including films and multilayers of Fe-Pt, Co-Pt and Fe-P-Rh alloys deposited on MgO and Al2O3 substrates. Our prior results have revealed that these materials have a rich variety of ferromagnetic, paramagnetic and antiferromagnetic phases which are sensitive functions of composition, substrate symmetry and layer thickness. Epitaxial antiferromagnetic films of FePt alloys exhibit a different phase diagram than bulk alloys. The antiferromagnetism of these materials has both spin ordering transitions and spin orienting transitions. The objectives include themore » study of exchange-inversion materials and the interface of these materials with ferromagnets. Our aim is to formulate a complete understanding of the magnetic ordering in these materials, as well as developing an understanding of how the spin structure is modified through contact with a ferromagnetic material at the interface. The ultimate goal is to develop the ability to tune the phase diagram of the materials to produce layered structures with tunable magnetic properties. The alloy systems that we will study have a degree of complexity and richness of magnetic phases that requires the use of the advanced tools offered by the DOE-operated national laboratory facilities, such as neutron and x-ray scattering to measure spin ordering, spin orientations, and element-specific magnetic moments. We plan to contribute to DOE’s mission of producing “Materials by Design” with properties determined by alloy composition and crystal structure. We have developed the methods for fabricating and have performed neutron diffraction experiments on some of the most interesting phases, and our work will serve to answer questions raised about the element-specific magnetizations using the magnetic x-ray dichroism techniques and interface magnetism in layered structures using polarized neutron reflectometry. Through application of these techniques to understand the materials fabricated in our laboratory, we will employ a tight feedback loop to tailor the magnetic properties on demand. Developing the ability to control magnetic anisotropy is essential for creating the next generation of magnetic storage media (for hard disks, for example), where individual bit sizes have already become smaller than 100nm in the largest dimension. Still smaller bits and higher storage density will require the ability to exquisitely tailor magnetic media properties at the atomic level, the ultimate goal of our study.« less

Fiber Optic Magnetic Field Sensors Using Metallic Glass Coatings.

NASA Astrophysics Data System (ADS)

Wang, Yu.

1990-01-01

In this thesis we have investigated the use of a magnetostrictive material with a single-mode optical fiber for detecting weak magnetic fields. The amorphous alloy Metglas^circler 2605SC (Fe_{81}B_ {13.5}Si_{3.5} C_2) was chosen as the magnetostrictive material because of the combination of its large magnetostriction and small magnetic anisotropy field among all available metals. For efficient coupling between the magnetostrictive material and the optical fiber, the magnetostrictive material was directly deposited onto the single-mode optical fiber. The coated fibers were used as the sensing element in the fiber optic magnetic field sensor (FOMS). Very high quality thick metallic glass films of the Metglas 2605 SC have been deposited using triode-magneton sputtering. This is the first time such material has been successfully deposited onto an optical fiber or onto any other substrate. The films were also deposited onto glass slides to allow the study of the magnetic properties of the film. The thicknesses of these films were 5-15 mum. The magnetic property of primary interest for our sensor application is the induced longitudinal magnetostrictive strain. However, the other magnetic properties such as magnetic anisotropy, surface and bulk coercivities, magnetic homogeneity and magnetization all affect the magnetostrictive response of the material. We have used ferromagnetic resonance (FMR) at microwave frequencies to study the magnetic anisotropy and homogeneity; vibrating sample magnetometry (VSM) to study the bulk magnetic hysteresis responses and coercivity; and the longitudinal magneto-optic kerr effect (LMOKE) to study the surface magnetic hysteresis responses and coercivity. The isothermalmagnetic annealing effect on these properties has also been studied in detail. The fiber optic magnetic field sensor constructed using the metallic-glass-coated fiber was tested. An electronic feedback control loop using a PZT cylinder was constructed for stabilizing the sensor operation. Magnetic field detection at different dither frequencies was studied in detail. The estimated minimum detectable magnetic field was about 3 times 10^{-7 } Oe. A simplified elastic model was used for the theoretical calculation of the phase shift induced in a metallic-glass -coated optical fiber with a longitudinal applied magnetic field. The phase shift as a function of coating thickness was calculated, and the experimental results at certain thicknesses were compared with the calculation. The frequency response of the FOMS was also studied in some detail. Three different configurations were used for the study of the frequency response. The results indicate that the resonances observed in the FOMS are most likely related to the mechanical resonance of the optical fiber.

Atomic scale imaging of magnetic circular dichroism by achromatic electron microscopy.

PubMed

Wang, Zechao; Tavabi, Amir H; Jin, Lei; Rusz, Ján; Tyutyunnikov, Dmitry; Jiang, Hanbo; Moritomo, Yutaka; Mayer, Joachim; Dunin-Borkowski, Rafal E; Yu, Rong; Zhu, Jing; Zhong, Xiaoyan

2018-03-01

In order to obtain a fundamental understanding of the interplay between charge, spin, orbital and lattice degrees of freedom in magnetic materials and to predict and control their physical properties 1-3 , experimental techniques are required that are capable of accessing local magnetic information with atomic-scale spatial resolution. Here, we show that a combination of electron energy-loss magnetic chiral dichroism 4 and chromatic-aberration-corrected transmission electron microscopy, which reduces the focal spread of inelastically scattered electrons by orders of magnitude when compared with the use of spherical aberration correction alone, can achieve atomic-scale imaging of magnetic circular dichroism and provide element-selective orbital and spin magnetic moments atomic plane by atomic plane. This unique capability, which we demonstrate for Sr 2 FeMoO 6 , opens the door to local atomic-level studies of spin configurations in a multitude of materials that exhibit different types of magnetic coupling, thereby contributing to a detailed understanding of the physical origins of magnetic properties of materials at the highest spatial resolution.

Magnetic Materials Suitable for Fission Power Conversion in Space Missions

NASA Technical Reports Server (NTRS)

Bowman, Cheryl L.

2012-01-01

Terrestrial fission reactors use combinations of shielding and distance to protect power conversion components from elevated temperature and radiation. Space mission systems are necessarily compact and must minimize shielding and distance to enhance system level efficiencies. Technology development efforts to support fission power generation scenarios for future space missions include studying the radiation tolerance of component materials. The fundamental principles of material magnetism are reviewed and used to interpret existing material radiation effects data for expected fission power conversion components for target space missions. Suitable materials for the Fission Power System (FPS) Project are available and guidelines are presented for bounding the elevated temperature/radiation tolerance envelope for candidate magnetic materials.

Modeling of non-ideal hard permanent magnets with an affine-linear model, illustrated for a bar and a horseshoe magnet

NASA Astrophysics Data System (ADS)

Glane, Sebastian; Reich, Felix A.; Müller, Wolfgang H.

2017-11-01

This study is dedicated to continuum-scale material modeling of isotropic permanent magnets. An affine-linear extension to the commonly used ideal hard model for permanent magnets is proposed, motivated, and detailed. In order to demonstrate the differences between these models, bar and horseshoe magnets are considered. The structure of the boundary value problem for the magnetic field and related solution techniques are discussed. For the ideal model, closed-form analytical solutions were obtained for both geometries. Magnetic fields of the boundary value problems for both models and differently shaped magnets were computed numerically by using the boundary element method. The results show that the character of the magnetic field is strongly influenced by the model that is used. Furthermore, it can be observed that the shape of an affine-linear magnet influences the near-field significantly. Qualitative comparisons with experiments suggest that both the ideal and the affine-linear models are relevant in practice, depending on the magnetic material employed. Mathematically speaking, the ideal magnetic model is a special case of the affine-linear one. Therefore, in applications where knowledge of the near-field is important, the affine-linear model can yield more accurate results—depending on the magnetic material.

Functional Magnetic Resonance Imaging (MRI) and MRI Tractography in Progressive Supranuclear Palsy-Like Syndrome

PubMed Central

Vaphiades, Michael S.; Visscher, Kristina; Rucker, Janet C.; Vattoth, Surjith; Roberson, Glenn H.

2015-01-01

ABSTRACT An 18-year-old woman underwent an uneventful ascending aortic aneurysm repair then developed progressive supranuclear palsy-like syndrome. Extensive neuroimaging including contrasted fat-suppressed cranial and orbital magnetic resonance imaging (MRI), MRI tractography, and functional MRI (fMRI) revealed no clear radiographic involvement except for a single tiny hypoechoic midbrain dot on the T2*-weighted gradient-echo imaging, which is not considered sufficient to account for the patient’s deficits. This case attests to the occult nature of this rare and devastating syndrome. PMID:27928334

Dichloroacetate treatment in Leigh syndrome caused by mitochondrial DNA mutation.

PubMed

Takanashi, J; Sugita, K; Tanabe, Y; Maemoto, T; Niimi, H

1997-01-01

Sodium dichloroacetate (DCA) was administered to a 1-year-old female case of Leigh syndrome, who had a T > G point mutation at nt 8993 of mitochondrial DNA. Her biochemical and clinical symptoms improved gradually, but proton magnetic resonance spectroscopy revealed reduction of the N-acetylaspartate/creatine ratio, and magnetic resonance imaging showed progressive cerebral atrophy despite the DCA therapy. These results suggest that DCA therapy may not retard the progress of the primary disease in Leigh syndrome, but produced clinical improvement most likely by reducing toxic accumulation of lactate.

Hybrid magnetic materials formed by ferritin intercalated into a layered double hydroxide

NASA Astrophysics Data System (ADS)

Clemente-León, Miguel; Coronado, Eugenio; Primo, Vicent; Ribera, Antonio; Soriano-Portillo, Alejandra

2008-12-01

A hybrid magnetic material formed by ferritin intercalated into a layered double hydroxide (LDH) of Mg and Al (Mg/Al molar ratio 2) is prepared and characterized through powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectroscopy, electron probe microanalysis (EPMA) and high resolution transmission electron microscopy (HRTEM). One observes an enhancement in the thermal stability of the ferritin molecules when they are inserted in the layered material. Magnetic measurements of the hybrid material exhibit the typical superparamagnetic behaviour of the ferritin molecule. On the other hand, the intercalation of ferritin into the LDH guarantees a homogeneous dispersion of the ferritin molecules, which do not aggregate even after calcination of the sample. This feature allows obtaining well-dispersed magnetic metal oxide nanoparticles upon calcination of the hybrid material.

FY2011 Annual Progress Report for Propulsion Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, Patrick B.; Schutte, Carol L.; Gibbs, Jerry L.

Annual Progress Report for Propulsion Materials focusing on enabling and innovative materials technologies that are critical in improving the efficiency of advanced engines by providing enabling materials support for combustion, hybrid, and power electronics development.

Magnetism at grain boundary interfacesin the colossal permittivity dielectric material; In+Nb Co-Doped Rutile

NASA Astrophysics Data System (ADS)

Berlie, Adam; Terry, Ian; Cottrell, Stephen; Hu, Wanbiao; Liu, Yun

With the emphasis in recent years on understanding novel materials with potential technological applications this work seeks to understand magnetic ordering within the colossal-permittivity material, In+Nb co-doped rutile (TiO2). Evidence for a spin-freezing transition was reported from a step like feature in the dielectic data below 50 K but this was largly glossed over. Within this work we show that below 300 K there is a slowing down of magnetic fluctuations associated with the electronic magnetism due to the defect-dipoles created by the co-doping, but the muon spectroscopy results are strongly suggestive of the behaviour being localised to the edges/interfaces of particles/grains. The TC is strongly dependent on the doping level of the samples that presents novel way to control the magnetism and ultimately magneto-electric coupling within a dielectric material.

Improved magnetic encoding device and method for making the same. [Patent application

DOEpatents

Fox, R.J.

A magnetic encoding device and method for making the same are provided for use as magnetic storage media in identification control applications that give output signals from a reader that are of shorter duration and substantially greater magnitude than those of the prior art. Magnetic encoding elements are produced by uniformly bending wire or strip stock of a magnetic material longitudinally about a common radius to exceed the elastic limit of the material and subsequently mounting the material so that it is restrained in an unbent position on a substrate of nonmagnetic material. The elements are spot weld attached to a substrate to form a binary coded array of elements according to a desired binary code. The coded substrate may be enclosed in a plastic laminate structure. Such devices may be used for security badges, key cards, and the like and may have many other applications. 7 figures.

Method for making an improved magnetic encoding device

DOEpatents

Fox, Richard J.

1981-01-01

A magnetic encoding device and method for making the same are provided for use as magnetic storage mediums in identification control applications which give output signals from a reader that are of shorter duration and substantially greater magnitude than those of the prior art. Magnetic encoding elements are produced by uniformly bending wire or strip stock of a magnetic material longitudinally about a common radius to exceed the elastic limit of the material and subsequently mounting the material so that it is restrained in an unbent position on a substrate of nonmagnetic material. The elements are spot weld attached to a substrate to form a binary coded array of elements according to a desired binary code. The coded substrate may be enclosed in a plastic laminate structure. Such devices may be used for security badges, key cards, and the like and may have many other applications.

Lightning current detector

NASA Technical Reports Server (NTRS)

Livermore, S. F. (Inventor)

1978-01-01

An apparatus for measuring the intensity of current produced in an elongated electrical conductive member by a lightning strike for determining the intensity of the lightning strike is presented. The apparatus includes an elongated strip of magnetic material that is carried within an elongated tubular housing. A predetermined electrical signal is recorded along the length of said elongated strip of magnetic material. One end of the magnetic material is positioned closely adjacent to the electrically conductive member so that the magnetic field produced by current flowing through said electrically conductive member disturbs a portion of the recorded electrical signal directly proportional to the intensity of the lightning strike.

Technology for fabrication of a micromagnet on a tip of a MFM/MRFM probe

DOEpatents

Pelekhov, Denis V.; Hammel, P. Chris; Nunes, Jr., Geoffrey; Midzor, Melissa M.; Roukes, Michael

2004-01-13

A method for coating the tip of a mechanical resonator for use in magnetic force microscopy and magnetic resonance force microscopy in which the tip is coated with a ferromagnetic material and the cantilever is not, and the product resulting from the method. A cantilever and incorporated tip are coated with a photoresist, except that surface tension keeps photoresist off the tip. The cantilever and tip are then coated with a magnetic material. Next, acetone is used to lift off the magnetic material from the cantilever but not from the tip.

Detection of magnetism in the red imported fire ant (Solenopsis invicta) using magnetic resonance imaging.

PubMed

Slowik, T J; Green, B L; Thorvilson, H G

1997-01-01

Red imported fire ant (Solenopsis invicta) workers, queens, and alates were analyzed by magnetic resonance imaging (MRI) for the presence of natural magnetism. Images of ants showed distortion patterns similar to those of honey bees and monarch butterflies, both of which possess ferromagnetic material. The bipolar ring patterns of MRI indicated the presence in fire ants of small amounts of internal magnetic material, which may be used in orientation behaviors, as in the honey bees.

Pulsed Magnetic Field System for Magnetized Target Experiments at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Rhodes, M. A.; Solberg, J. M.; Logan, B. G.; Perkins, L. J.

2014-10-01

High-magnitude magnetic fields applied to inertially confined targets may improve fusion yield and enable basic science applications. We discuss the development of a pulsed magnetic field system for NIF with the goal of applying 10--70 T to various NIF targets. While the driver may be little more than a spark-gap switched capacitor, numerous complex challenges exist in fielding such a system on NIF. The coil surrounding the metallic hohlraum drives induced current in the hohlraum wall. Both the coil and hohlraum wall must survive ohmic heating and J × B forces for several microseconds. Pulsed power must couple to the coil in the NIF environment. The system must not cause late-time optics damage due to debris. There is very limited volume for the driver in a NIF Diagnostic Instrument Manipulator (DIM). We are modeling the coil and hohlraum MHD effects with the LLNL code, ALE3D. However, the simulations lack complete and accurate data for all the required thermo-physical material properties over the expected range of temperatures (below vaporization) and pressures. Therefore, substantial experimental development is planned in the coming year. We present coil and hohlraum simulations results, overall system design, and progress towards an operational prototype test-stand. LLNL is operated by LLNS, LLC, for the U.S. D.O.E., NNSA under Contract DE-AC52-07NA27344. This work was supported by LLNL LDRD 14-ER-028.

Magnetic Analysis of Post-mortem Hippocampal Tissue from Alzheimer's Patients: Changes with Progression of the Disease.

NASA Astrophysics Data System (ADS)

Fuller, M.; Zinin, P.; Favia, J.; Tatsumi, L.; Kletetschka, G.; Adachi, T.

2007-12-01

Increases of iron in the human brain with age have been observed and may be accompanied by the development of neurodegenerative diseases, such as Alzheimer's. We have measured the magnetic characteristics of several sets of slides of hippocampal tissue from deceased Alzheimer patients. The slides were made available by the Harvard Brain Bank. The pathology of the tissue was classified in the Braak stages I to VI used to describe the progression of the disease. In general, the slides from patients with higher Braak stages and development of fibrillary tangles and plaques had greater magnetic moments than did those with Braak stage II. However, the peak values were at stage IV and V. To mitigate errors due to the inevitable differences in masses of the tissue on individual slides and their precise location in the hippocampus, ratios of magnetic properties were also observed. Ratios of Anhysteretic Remanent Magnetizaton (ARM) to Isothermal Remanent Magnetization (IRM) were obtained and showed a decrease from Stage II to the more advanced stages, with the minimum values at stages IV and V. The acquisition and demagnetization of IRM are consistent with the presence of magnetite, but also indicate a magnetically harder phase.

Method for residual stress relief and retained austenite destabilization

DOEpatents

Ludtka, Gerard M.

2004-08-10

A method using of a magnetic field to affect residual stress relief or phase transformations in a metallic material is disclosed. In a first aspect of the method, residual stress relief of a material is achieved at ambient temperatures by placing the material in a magnetic field. In a second aspect of the method, retained austenite stabilization is reversed in a ferrous alloy by applying a magnetic field to the alloy at ambient temperatures.

Temperature-dependent liquid metal flowrate control device

DOEpatents

Carlson, Roger D.

1978-01-01

A temperature-dependent liquid metal flowrate control device includes a magnet and a ferromagnetic member defining therebetween a flow path for liquid metal, the ferromagnetic member being formed of a material having a curie temperature at which a change in the flow rate of the liquid metal is desired. According to the preferred embodiment the magnet is a cylindrical rod magnet axially disposed within a cylindrical member formed of a curie material and having iron pole pieces at the ends. A cylindrical iron shunt and a thin wall stainless steel barrier are disposed in the annulus between magnet and curie material. Below the curie temperature flow between steel barrier and curie material is impeded and above the curie temperature flow impedance is reduced.

Large gap magnetic suspension system

NASA Technical Reports Server (NTRS)

Abdelsalam, Moustafa K.; Eyssa, Y. M.

1991-01-01

The design of a large gap magnetic suspension system is discussed. Some of the topics covered include: the system configuration, permanent magnet material, levitation magnet system, superconducting magnets, resistive magnets, superconducting levitation coils, resistive levitation coils, levitation magnet system, and the nitrogen cooled magnet system.

Magnetic switch for reactor control rod

DOEpatents

Germer, John H.

1986-01-01

A magnetic reed switch assembly for activating an electromagnetic grapple utilized to hold a control rod in position above a reactor core. In normal operation the magnetic field of a permanent magnet is short-circuited by a magnetic shunt, diverting the magnetic field away from the reed switch. The magnetic shunt is made of a material having a Curie-point at the desired release temperature. Above that temperature the material loses its ferromagnetic properties, and the magnetic path is diverted to the reed switch which closes and short-circuits the control circuit for the control rod electromagnetic grapple which allows the control rod to drop into the reactor core for controlling the reactivity of the core.

Association of Progression of Carotid Artery Wall Volume and Recurrent Transient Ischemic Attack or Stroke: A Magnetic Resonance Imaging Study.

PubMed

Lu, Mingming; Peng, Peng; Cui, Yuanyuan; Qiao, Huiyu; Li, Dongye; Cai, Jianming; Zhao, Xihai

2018-03-01

This study aimed to investigate the association between carotid plaque progression and subsequent recurrent events using magnetic resonance imaging. Sixty-three symptomatic patients with ipsilateral carotid atherosclerotic stenosis (30%-69% stenosis) determined by ultrasound underwent first and second carotid artery magnetic resonance imaging for carotid artery at baseline and ≥6 months after the first scan, respectively. All the patients had clinical follow-up after the second magnetic resonance scan for ≤5 years until the onset of recurrent transient ischemic attack or stroke. Presence/absence of carotid plaque compositional features, particularly intraplaque hemorrhage and fibrous cap rupture was identified. The annual progression of carotid wall volume between 2 magnetic resonance scans was measured. Univariate and multivariate Cox regression was used to calculate the hazard ratio and corresponding 95% confidence interval of carotid plaque features in discriminating recurrent events. Receiver-operating-characteristic-curve analysis was conducted to determine the area-under-the-curve of carotid plaque features in predicting recurrent events. Sixty-three patients (mean age: 66.5±10.0 years old; 54 males) were eligible for final statistics analysis. During a mean follow-up duration of 55.1±13.6 months, 14.3% of patients (n=9) experienced ipsilateral recurrent transient ischemic attack/stroke. The annual progression of carotid wall volume was significantly associated with recurrent events before (hazard ratio, 1.14 per 10 mm 3 ; 95% confidence interval, 1.02-1.27; P =0.019) and after (hazard ratio, 1.19 per 10 mm3; 95% confidence interval, 1.03-1.37; P =0.022) adjusted for confounding factors. In discriminating the recurrence of transient ischemia attack/stroke, receiver-operator curve analysis indicated that combined with annual progression of wall volume, there was a significant incremental improvement in the area-under-the-curve of intraplaque hemorrhage (area-under-the-curve: 0.69-0.81) and fibrous cap rupture (area-under-the-curve: 0.73-0.84). The annual progression of carotid wall volume is independently associated with recurrent ischemic cerebrovascular events, and this measurement has added value for intraplaque hemorrhage and fibrous cap rupture in predicting future events. © 2018 American Heart Association, Inc.

Polar Vortices Observed in Ferroelectric | Berkeley Lab

Science.gov Websites

vortices" that appear to be the electrical cousins of magnetic skyrmions holds intriguing structures are confined to magnetic systems and aren't possible in ferroelectric materials, but through the . Ferroic materials display unique electrical or magnetic properties - or both in the case of multiferroics

Enhanced magnetocaloric effect material

DOEpatents

Lewis, Laura J. H.

2006-07-18

A magnetocaloric effect heterostructure having a core layer of a magnetostructural material with a giant magnetocaloric effect having a magnetic transition temperature equal to or greater than 150 K, and a constricting material layer coated on at least one surface of the magnetocaloric material core layer. The constricting material layer may enhance the magnetocaloric effect by restriction of volume changes of the core layer during application of a magnetic field to the heterostructure. A magnetocaloric effect heterostructure powder comprising a plurality of core particles of a magnetostructural material with a giant magnetocaloric effect having a magnetic transition temperature equal to or greater than 150 K, wherein each of the core particles is encapsulated within a coating of a constricting material is also disclosed. A method for enhancing the magnetocaloric effect within a giant magnetocaloric material including the step of coating a surface of the magnetocaloric material with a constricting material is disclosed.

Optimal Design of Magnetic ComponentsinPlasma Cutting Power Supply

NASA Astrophysics Data System (ADS)

Jiang, J. F.; Zhu, B. R.; Zhao, W. N.; Yang, X. J.; Tang, H. J.

2017-10-01

Phase-shifted transformer and DC reactor are usually needed in chopper plasma cutting power supply. Because of high power rate, the loss of magnetic components may reach to several kilowatts, which seriously affects the conversion efficiency. Therefore, it is necessary to research and design low loss magnetic components by means of efficient magnetic materials and optimal design methods. The main task in this paper is to compare the core loss of different magnetic material, to analyze the influence of transformer structure, winding arrangement and wire structure on the characteristics of magnetic component. Then another task is to select suitable magnetic material, structure and wire in order to reduce the loss and volume of magnetic components. Based on the above outcome, the optimization design process of transformer and dc reactor are proposed in chopper plasma cutting power supply with a lot of solutions. These solutions are analyzed and compared before the determination of the optimal solution in order to reduce the volume and power loss of the two magnetic components and improve the conversion efficiency of plasma cutting power supply.

Challenges in the development of magnetic particles for therapeutic applications.

PubMed

Barry, Stephen E

2008-09-01

Certain iron-based particle formulations have useful magnetic properties that, when combined with low toxicity and desirable pharmacokinetics, encourage their development for therapeutic applications. This mini-review begins with background information on magnetic particle use as MRI contrast agents and the influence of material size on pharmacokinetics and tissue penetration. Therapeutic investigations, including (1) the loading of bioactive materials, (2) the use of stationary, high-gradient (HG) magnetic fields to concentrate magnetic particles in tissues or to separate material bound to the particles from the body, and (3) the application of high power alternating magnetic fields (AMF) to generate heat in magnetic particles for hyperthermic therapeutic applications are then surveyed. Attention is directed mainly to cancer treatment, as selective distribution to tumors is well-suited to particulate approaches and has been a focus of most development efforts. While magnetic particles have been explored for several decades, their use in therapeutic products remains minimal; a discussion of future directions and potential ways to better leverage magnetic properties and to integrate their use into therapeutic regimens is discussed.

Preparation and magnetic properties of phthalocyanine-based carbon materials containing transition metals

NASA Astrophysics Data System (ADS)

Honda, Z.; Sato, S.; Hagiwara, M.; Kida, T.; Sakai, M.; Fukuda, T.; Kamata, N.

2016-07-01

A simple method for the preparation of bulk quantities of magnetic carbon materials, which contain uniformly dispersed transition metals (M = Fe, Co, Ni, and Cu) as the magnetic components, is presented. By using highly chlorinated metal phthalocyanine as the building block and potassium as the coupling reagent, phthalocyanine-based carbon materials (PBCMs) containing transition metals were obtained. Our experiments demonstrate the structure of these PBCMs consists of transition metals embedded in graphitic carbon that includes a square planar MN4 magnetic core and the Fe and Co-PBCM possess spontaneous magnetization at room temperature. In addition, carbon-coated transition metal particles were obtained by the Wurtz-type reaction with excess amount of potassium coupling agent. The large transition metal surface area and magnetization of these M-PBCMs are useful for spintronic and catalytic applications.

From biowaste to magnet-responsive materials for water remediation from polycyclic aromatic hydrocarbons.

PubMed

Nisticò, Roberto; Cesano, Federico; Franzoso, Flavia; Magnacca, Giuliana; Scarano, Domenica; Funes, Israel G; Carlos, Luciano; Parolo, Maria E

2018-07-01

Composted urban biowaste-derived substances (BBS-GC) are used as carbon sources for the preparation of carbon-coated magnet-sensitive nanoparticles obtained via co-precipitation method and the subsequent thermal treatment at 550 °C under nitrogen atmosphere. A multitechnique approach has been applied to investigate the morphology, magnetic properties, phase composition, thermal stability of the obtained magnet-sensitive materials. In particular, pyrolysis-induced modifications affecting the BBS-GC/carbon shell were highlighted. The adsorption capacity of such bio-derivative magnetic materials for the removal of hydrophobic contaminants such as polycyclic aromatic hydrocarbons was evaluated in order to verify their potential application in wastewater remediation process. The promising results suggest their use as a new generation of magnet-responsive easily-recoverable adsorbents for water purification treatments. Copyright © 2018 Elsevier Ltd. All rights reserved.

Continuous magnetic flux pump

NASA Technical Reports Server (NTRS)

Hildebrandt, A. F.; Elleman, D. D.; Whitmore, F. C. (Inventor)

1966-01-01

A method and means for altering the intensity of a magnetic field by transposing flux from one location to the location desired fro the magnetic field are examined. The device described includes a pair of communicating cavities formed in a block of superconducting material, is dimensioned to be insertable into one of the cavities and to substantially fill the cavity. Magnetic flux is first trapped in the cavities by establishing a magnetic field while the superconducting material is above the critical temperature at which it goes superconducting. Thereafter, the temperature of the material is reduced below the critical value, and then the exciting magnetic field may be removed. By varying the ratios of the areas of the two cavities, it is possible to produce a field having much greater flux density in the second, smaller cavity, into which the flux transposed.

High-gradient permanent magnet apparatus and its use in particle collection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Mengdawn; Ludtka, Gerard Michael; Avens, Larry R.

A high-gradient permanent magnet apparatus for capturing paramagnetic particles, the apparatus comprising: (i) at least two permanent magnets positioned with like poles facing each other; (ii) a ferromagnetic spacer separating the like poles; and (iii) a magnetizable porous filling material in close proximity to the at least two permanent magnets. Also described is a method for capturing paramagnetic particles in which a gas or liquid sample containing the paramagnetic particles is contacted with the high-gradient permanent magnet apparatus described above; wherein, during the contacting step, the gas or liquid sample contacts the magnetizable porous filling material of the high-gradient permanentmore » magnet apparatus, and at least a portion of the paramagnetic particles in the gas or liquid sample is captured on the magnetizable porous filling material.« less

Magnetically-induced solid-phase microextraction fiber actuation system for quantitative headspace and liquid sampling

DOEpatents

Harvey, Chris; Carter, Jerry; Chambers, David M.

2017-05-23

A magnetically-induced SPME fiber actuation system includes a SPME fiber holder and a SPME fiber holder actuator, for holding and magnetically actuating a SPME fiber assembly. The SPME fiber holder has a plunger with a magnetic material to which the SPME fiber assembly is connected, and the magnetic SPME fiber holder actuator has an elongated barrel with a loading chamber for receiving the SPME fiber assembly-connected SPME fiber holder, and an external magnet which induces axial motion of the magnetic material of the plunger to extend/retract the SPME fiber from/into the protective needle of the SPME fiber assembly.

TMS 2014 143rd Annual Meeting & Exhibition, Annual Meeting Supplemental Proceedings (ISBN: 978-1-118-88972-5)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nielsen, K; Zhukov, A; Ipatov, M

The Magnetic Materials for Energy Applications IV, held at the 2014, 143rd Annual Meeting of The Minerals, Metals, and Materials Society (TMS), brought together experts, young investigators, and students from this sub-discipline of materials science in order for them to share their latest discoveries and develop collaborations. This symposium, which is organized by The Minerals, Metals, and Materials Society, is an important event for this community of scientists. This year, over 50 high-level technical talks were planned over the course of the event. In addition, the students and young investigators in attendance ensured the maximum benefit to the next generation’smore » work force in this area of study. Meeting global energy needs in a clean, efficient, secure and sustainable manner is arguably the greatest challenge facing mankind today. Magnetic materials play a critical role in myriad devices for the collection, conversion, transmission and storage of energy. For example, high performance permanent magnets are currently in great demand for the generators in wind turbines and electric motors in hybrid vehicles. Other classes of advanced magnetic materials are essential for efficient inductors/transformers and motors. Energy efficient cooling based on the magnetocaloric effect is another exciting possibility which is rapidly becoming industrially viable. The potential energy savings related to refrigeration and air conditioning based on magnetocaloric materials are highly attractive. This symposium allowed experts in areas relating to the advanced characterization, simulation, and optimization of magnetic materials to convene and present their latest research. The types of interactions afforded by this event are beneficial to society at large primarily because they provide opportunities for the leaders within this field to learn from one another and thus improve the quality and productivity of their investigations. Additionally, the presence of young investigators and students with technical interests in this field provides promise that the United States will continue to be a leader in this area. The support provided by the Department of Energy for this event directly enhanced its impact on the field by helping a number of students, young investigators, and technical experts attend and participate in this event. This symposium brought together research experts and students in the field to present the latest developments on the science surrounding advanced characterization, simulation, and optimization of magnetic materials and their use in energy applications such as generation and magnetic cooling. A strong technical program, containing more than 50 presentations was developed and organized around the following technical sessions. A strong list of invited speakers contributed to the high quality of technical content. Rare Earth Permanent Magnets: Processing, Characterization and Modeling Rare Earth Free Permanent Magnets Fundamentals of the Magnetocaloric Effect and Current Status of Magnetic Cooling Technology Magnetocaloric Materials High Performance Soft Magnets I High Performance Soft Magnets II« less

Magnetic moment in single crystalline BaFe2-xZnxAs2

NASA Astrophysics Data System (ADS)

Guo, Yanfeng; Wang, Xia; Li, Jun; Yamaura, Kazunari; Takayama-Muromachi, Eiji

2012-02-01

Nature of the magnetism for iron-based superconductors (FeSCs) has been actively studied since the discovery of this new family of compounds in 2008, largely owing to its significance for interpreting the paring mechanism. The approach through impurity substitution to shed light into this issue is always one of major ways. The substitution shows distinct responses to species of impurities, where partially replacement of Fe in parent FeSCs with a variety of d-metals like Co, Ni Ru, Rh, Pd, Ir, and Pt generally results in superconductivity, while recent progress in Zn doped FeSCs gives rather contrary result, where Zn severely degenerates the TC. Herein we show the magnetic and electrical studies on BaFe2-xZnxAs2 single crystals. Nonmagnetic Zn doping progressively suppresses the SDW without resulting in superconductivity, while it alternatively develops the spin-glass state, possibly suggestive of local magnetic moment around the Fe sites induced by Zn. The characterizations by X-ray diffraction, magnetic and electrical transport properties, specific heat capacity, and Hall coefficient have been done and the results will be discussed in detail.

Progress towards experimental realization of extreme-velocity flow-dominated magnetized plasmas

NASA Astrophysics Data System (ADS)

Weber, T. E.; Adams, C. S.; Welch, D. R.; Kagan, G.; Bean, I. A.; Henderson, B. R.; Klim, A. J.

2017-10-01

Interactions of flow-dominated plasmas with other plasmas, neutral gases, magnetic fields, solids etc., take place with sufficient velocity that kinetic energy dominates the dynamics of the interaction (as opposed to magnetic or thermal energy, which dominates in most laboratory plasma experiments). Building upon progress made by the Magnetized Shock Experiment (MSX) at LANL, we are developing the experimental and modeling capability to increase our ultimate attainable plasma velocities well in excess of 1000 km/s. Ongoing work includes designing new pulsed power switches, triggering, and inductive adder topologies; development of novel high-speed optical diagnostics; and exploration of new numerical techniques to specifically model the unique physics of translating/stagnating flow-dominated plasmas. Furthering our understanding of the physical mechanisms of energy conversion from kinetic to other forms, such as thermal energy, non-thermal tails/accelerated populations, enhanced magnetic fields, and radiation (both continuum and line), has wide-ranging significance in basic plasma science, astrophysics, and plasma technology applications such as inertial confinement fusion and intense radiation sources. This work is supported by the U.S. Department of Energy, National Nuclear Security Administration. LA-UR-17-25786.

Polydimethylsiloxane films doped with NdFeB powder: magnetic characterization and potential applications in biomedical engineering and microrobotics.

PubMed

Iacovacci, V; Lucarini, G; Innocenti, C; Comisso, N; Dario, P; Ricotti, L; Menciassi, A

2015-12-01

This work reports the fabrication, magnetic characterization and controlled navigation of film-shaped microrobots consisting of a polydimethylsiloxane-NdFeB powder composite material. The fabrication process relies on spin-coating deposition, powder orientation and permanent magnetization. Films with different powder concentrations (10 %, 30 %, 50 % and 70 % w/w) were fabricated and characterized in terms of magnetic properties and magnetic navigation performances (by exploiting an electromagnet-based platform). Standardized data are provided, thus enabling the exploitation of these composite materials in a wide range of applications, from MEMS/microrobot development to biomedical systems. Finally, the possibility to microfabricate free-standing polymeric structures and the biocompatibility of the proposed composite materials is demonstrated.

Leach-proof magnetic thrombolytic nanoparticles and coatings of enhanced activity

NASA Astrophysics Data System (ADS)

Drozdov, Andrey S.; Vinogradov, Vasiliy V.; Dudanov, Ivan P.; Vinogradov, Vladimir V.

2016-06-01

Despite the fact that magnetic thrombolytic composites is an emerging area, all known so far systems are based on the similar mechanism of action: thrombolytic enzyme releases from the magnetic carrier leaving non-active matrix, thus making the whole system active only for a limited period of time. Such systems often have very complex structure organization and composition, consisting of materials not approved for parenteral injection, making them poor candidates for real clinical trials and implementation. Here we report, for the first time, the production of thrombolytic magnetic composite material with non-releasing behavior and prolonged action. Obtained composite shows good thrombolytic activity, consists of fully biocompatible materials and could be applied as infinitely active thrombolytic coatings or magnetically-targetable thrombolytic agents.

High temperature refrigerator

DOEpatents

Steyert, Jr., William A.

1978-01-01

A high temperature magnetic refrigerator which uses a Stirling-like cycle in which rotating magnetic working material is heated in zero field and adiabatically magnetized, cooled in high field, then adiabatically demagnetized. During this cycle said working material is in heat exchange with a pumped fluid which absorbs heat from a low temperature heat source and deposits heat in a high temperature reservoir. The magnetic refrigeration cycle operates at an efficiency 70% of Carnot.

Magnetic and electrical properties of FeSi/FeSi-ZrO 2 multilayers prepared by EB-PVD

NASA Astrophysics Data System (ADS)

Bi, Xiaofang; Lan, Weihua; Ou, Shengquan; Gong, Shengkai; Xu, Huibin

2003-04-01

FeSi/FeSi-ZrO 2 and FeSi/ZrO 2 multilayer materials were prepared by electron beam physical vapor deposition with the FeSi-ZrO 2 layer thickness about 0.6 μm, and their magnetic and electrical properties were studied as a function of FeSi layer thickness. With increasing FeSi layer thickness from 0.3 to 3 μm, the coercivity decreased from 0.92 to 0.31 kA/m and the saturation magnetization changed from 164 to 186 emu/g. The effect of the layer number on the magnetic properties was discussed in terms of interfacial mixing and oxidation. It was also discovered that the magnetic properties of the multilayer materials were affected by the spacer material, exhibiting higher saturation magnetization and lower coercivity for the FeSi/FeSi-ZrO 2 than those for the FeSi/ZrO 2 with the same individual layer thicknesses. This behavior could be explained by the weaker magnetic interaction between FeSi layers separated by the non-magnetic ZrO 2 layer. Furthermore, the electrical resistivity changed from 1850 to 1250 μΩ cm for the multilayer materials for the FeSi thickness increasing from 0.30 to 3 μm.

Comparison of the Supercooled Spin Liquid States in the Pyrochlore Magnets Dy2Ti2O7 and Ho2Ti2O7

NASA Astrophysics Data System (ADS)

Eyal, Anna; Eyvazov, Azar B.; Dusad, Ritika; Munsie, Timothy J. S.; Luke, Graeme M.; Davis, J. C. Séamus

Despite a well-ordered crystal structure and strong magnetic interactions between the Dy or Ho ions, no long-range magnetic order has been detected in the pyrochlore titanates Ho2Ti2O7 and Dy2Ti2O7. The low temperature state in these materials is governed by spin-ice rules. These constrain the Ising like spins in the materials, yet does not result in a global broken symmetry state. To explore the actual magnetic phases, we simultaneously measure the time- and frequency-dependent magnetization dynamics of Dy2Ti2O7 and Ho2Ti2O7 using toroidal, boundary-free magnetization transport techniques. We demonstrate a distinctive behavior of the magnetic susceptibility of both compounds, that is indistinguishable in form from the permittivity of supercooled dipolar liquids. Moreover, we show that the microscopic magnetic relaxation times for both materials increase along a super-Arrhenius trajectory also characteristic of supercooled glass-forming liquids. Both materials therefore exhibit characteristics of a supercooled spin liquid. Strongly-correlated dynamics of loops of spins is suggested as a possible mechanism which could account for these findings. Potential connections to many-body spin localization will also be discussed.

Aptamer-functionalized nano-biosensors.

PubMed

Chiu, Tai-Chia; Huang, Chih-Ching

2009-01-01

Nanomaterials have become one of the most interesting sensing materials because of their unique size- and shape-dependent optical properties, high surface energy and surface-to-volume ratio, and tunable surface properties. Aptamers are oligonucleotides that can bind their target ligands with high affinity. The use of nanomaterials that are bioconjugated with aptamers for selective and sensitive detection of analytes such as small molecules, metal ions, proteins, and cells has been demonstrated. This review focuses on recent progress in the development of biosensors by integrating functional aptamers with different types of nanomaterials, including quantum dots, magnetic nanoparticles (NPs), metallic NPs, and carbon nanotubes. Colorimetry, fluorescence, electrochemistry, surface plasmon resonance, surface-enhanced Raman scattering, and magnetic resonance imaging are common detection modes for a broad range of analytes with high sensitivity and selectivity when using aptamer bioconjugated nanomaterials (Apt-NMs). We highlight the important roles that the size and concentration of nanomaterials, the secondary structure and density of aptamers, and the multivalent interactions play in determining the specificity and sensitivity of the nanosensors towards analytes. Advantages and disadvantages of the Apt-NMs for bioapplications are focused.

Effect of metal ions on photoluminescence, charge transport, magnetic and catalytic properties of all-inorganic colloidal nanocrystals and nanocrystal solids.

PubMed

Nag, Angshuman; Chung, Dae Sung; Dolzhnikov, Dmitriy S; Dimitrijevic, Nada M; Chattopadhyay, Soma; Shibata, Tomohiro; Talapin, Dmitri V

2012-08-22

Colloidal semiconductor nanocrystals (NCs) provide convenient "building blocks" for solution-processed solar cells, light-emitting devices, photocatalytic systems, etc. The use of inorganic ligands for colloidal NCs dramatically improved inter-NC charge transport, enabling fast progress in NC-based devices. Typical inorganic ligands (e.g., Sn(2)S(6)(4-), S(2-)) are represented by negatively charged ions that bind covalently to electrophilic metal surface sites. The binding of inorganic charged species to the NC surface provides electrostatic stabilization of NC colloids in polar solvents without introducing insulating barriers between NCs. In this work we show that cationic species needed for electrostatic balance of NC surface charges can also be employed for engineering almost every property of all-inorganic NCs and NC solids, including photoluminescence efficiency, electron mobility, doping, magnetic susceptibility, and electrocatalytic performance. We used a suite of experimental techniques to elucidate the impact of various metal ions on the characteristics of all-inorganic NCs and developed strategies for engineering and optimizing NC-based materials.

Fe₃O₄ Nanoparticles in Targeted Drug/Gene Delivery Systems.

PubMed

Shen, Lazhen; Li, Bei; Qiao, Yongsheng

2018-02-23

Fe₃O₄ nanoparticles (NPs), the most traditional magnetic nanoparticles, have received a great deal of attention in the biomedical field, especially for targeted drug/gene delivery systems, due to their outstanding magnetism, biocompatibility, lower toxicity, biodegradability, and other features. Naked Fe₃O₄ NPs are easy to aggregate and oxidize, and thus are often made with various coatings to realize superior properties for targeted drug/gene delivery. In this review, we first list the three commonly utilized synthesis methods of Fe₃O₄ NPs, and their advantages and disadvantages. In the second part, we describe coating materials that exhibit noticeable features that allow functionalization of Fe₃O₄ NPs and summarize their methods of drug targeting/gene delivery. Then our efforts will be devoted to the research status and progress of several different functionalized Fe₃O₄ NP delivery systems loaded with chemotherapeutic agents, and we present targeted gene transitive carriers in detail. In the following section, we illuminate the most effective treatment systems of the combined drug and gene therapy. Finally, we propose opportunities and challenges of the clinical transformation of Fe₃O₄ NPs targeting drug/gene delivery systems.

Plasma-wall interaction studies within the EUROfusion consortium: progress on plasma-facing components development and qualification

NASA Astrophysics Data System (ADS)

Brezinsek, S.; Coenen, J. W.; Schwarz-Selinger, T.; Schmid, K.; Kirschner, A.; Hakola, A.; Tabares, F. L.; van der Meiden, H. J.; Mayoral, M.-L.; Reinhart, M.; Tsitrone, E.; Ahlgren, T.; Aints, M.; Airila, M.; Almaviva, S.; Alves, E.; Angot, T.; Anita, V.; Arredondo Parra, R.; Aumayr, F.; Balden, M.; Bauer, J.; Ben Yaala, M.; Berger, B. M.; Bisson, R.; Björkas, C.; Bogdanovic Radovic, I.; Borodin, D.; Bucalossi, J.; Butikova, J.; Butoi, B.; Čadež, I.; Caniello, R.; Caneve, L.; Cartry, G.; Catarino, N.; Čekada, M.; Ciraolo, G.; Ciupinski, L.; Colao, F.; Corre, Y.; Costin, C.; Craciunescu, T.; Cremona, A.; De Angeli, M.; de Castro, A.; Dejarnac, R.; Dellasega, D.; Dinca, P.; Dittmar, T.; Dobrea, C.; Hansen, P.; Drenik, A.; Eich, T.; Elgeti, S.; Falie, D.; Fedorczak, N.; Ferro, Y.; Fornal, T.; Fortuna-Zalesna, E.; Gao, L.; Gasior, P.; Gherendi, M.; Ghezzi, F.; Gosar, Ž.; Greuner, H.; Grigore, E.; Grisolia, C.; Groth, M.; Gruca, M.; Grzonka, J.; Gunn, J. P.; Hassouni, K.; Heinola, K.; Höschen, T.; Huber, S.; Jacob, W.; Jepu, I.; Jiang, X.; Jogi, I.; Kaiser, A.; Karhunen, J.; Kelemen, M.; Köppen, M.; Koslowski, H. R.; Kreter, A.; Kubkowska, M.; Laan, M.; Laguardia, L.; Lahtinen, A.; Lasa, A.; Lazic, V.; Lemahieu, N.; Likonen, J.; Linke, J.; Litnovsky, A.; Linsmeier, Ch.; Loewenhoff, T.; Lungu, C.; Lungu, M.; Maddaluno, G.; Maier, H.; Makkonen, T.; Manhard, A.; Marandet, Y.; Markelj, S.; Marot, L.; Martin, C.; Martin-Rojo, A. B.; Martynova, Y.; Mateus, R.; Matveev, D.; Mayer, M.; Meisl, G.; Mellet, N.; Michau, A.; Miettunen, J.; Möller, S.; Morgan, T. W.; Mougenot, J.; Mozetič, M.; Nemanič, V.; Neu, R.; Nordlund, K.; Oberkofler, M.; Oyarzabal, E.; Panjan, M.; Pardanaud, C.; Paris, P.; Passoni, M.; Pegourie, B.; Pelicon, P.; Petersson, P.; Piip, K.; Pintsuk, G.; Pompilian, G. O.; Popa, G.; Porosnicu, C.; Primc, G.; Probst, M.; Räisänen, J.; Rasinski, M.; Ratynskaia, S.; Reiser, D.; Ricci, D.; Richou, M.; Riesch, J.; Riva, G.; Rosinski, M.; Roubin, P.; Rubel, M.; Ruset, C.; Safi, E.; Sergienko, G.; Siketic, Z.; Sima, A.; Spilker, B.; Stadlmayr, R.; Steudel, I.; Ström, P.; Tadic, T.; Tafalla, D.; Tale, I.; Terentyev, D.; Terra, A.; Tiron, V.; Tiseanu, I.; Tolias, P.; Tskhakaya, D.; Uccello, A.; Unterberg, B.; Uytdenhoven, I.; Vassallo, E.; Vavpetič, P.; Veis, P.; Velicu, I. L.; Vernimmen, J. W. M.; Voitkans, A.; von Toussaint, U.; Weckmann, A.; Wirtz, M.; Založnik, A.; Zaplotnik, R.; PFC contributors, WP

2017-11-01

The provision of a particle and power exhaust solution which is compatible with first-wall components and edge-plasma conditions is a key area of present-day fusion research and mandatory for a successful operation of ITER and DEMO. The work package plasma-facing components (WP PFC) within the European fusion programme complements with laboratory experiments, i.e. in linear plasma devices, electron and ion beam loading facilities, the studies performed in toroidally confined magnetic devices, such as JET, ASDEX Upgrade, WEST etc. The connection of both groups is done via common physics and engineering studies, including the qualification and specification of plasma-facing components, and by modelling codes that simulate edge-plasma conditions and the plasma-material interaction as well as the study of fundamental processes. WP PFC addresses these critical points in order to ensure reliable and efficient use of conventional, solid PFCs in ITER (Be and W) and DEMO (W and steel) with respect to heat-load capabilities (transient and steady-state heat and particle loads), lifetime estimates (erosion, material mixing and surface morphology), and safety aspects (fuel retention, fuel removal, material migration and dust formation) particularly for quasi-steady-state conditions. Alternative scenarios and concepts (liquid Sn or Li as PFCs) for DEMO are developed and tested in the event that the conventional solution turns out to not be functional. Here, we present an overview of the activities with an emphasis on a few key results: (i) the observed synergistic effects in particle and heat loading of ITER-grade W with the available set of exposition devices on material properties such as roughness, ductility and microstructure; (ii) the progress in understanding of fuel retention, diffusion and outgassing in different W-based materials, including the impact of damage and impurities like N; and (iii), the preferential sputtering of Fe in EUROFER steel providing an in situ W surface and a potential first-wall solution for DEMO.

Plasma–wall interaction studies within the EUROfusion consortium: progress on plasma-facing components development and qualification

DOE PAGES

Brezinsek, S.; Coenen, J. W.; Schwarz-Selinger, T.; ...

2017-06-14

The provision of a particle and power exhaust solution which is compatible with first-wall components and edge-plasma conditions is a key area of present-day fusion research and mandatory for a successful operation of ITER and DEMO. The work package plasma-facing components (WP PFC) within the European fusion programme complements with laboratory experiments, i.e. in linear plasma devices, electron and ion beam loading facilities, the studies performed in toroidally confined magnetic devices, such as JET, ASDEX Upgrade, WEST etc. The connection of both groups is done via common physics and engineering studies, including the qualification and specification of plasma-facing components, andmore » by modelling codes that simulate edge-plasma conditions and the plasma–material interaction as well as the study of fundamental processes. WP PFC addresses these critical points in order to ensure reliable and efficient use of conventional, solid PFCs in ITER (Be and W) and DEMO (W and steel) with respect to heat-load capabilities (transient and steady-state heat and particle loads), lifetime estimates (erosion, material mixing and surface morphology), and safety aspects (fuel retention, fuel removal, material migration and dust formation) particularly for quasi-steady-state conditions. Alternative scenarios and concepts (liquid Sn or Li as PFCs) for DEMO are developed and tested in the event that the conventional solution turns out to not be functional. Here, we present an overview of the activities with an emphasis on a few key results: (i) the observed synergistic effects in particle and heat loading of ITER-grade W with the available set of exposition devices on material properties such as roughness, ductility and microstructure; (ii) the progress in understanding of fuel retention, diffusion and outgassing in different W-based materials, including the impact of damage and impurities like N; and (iii), the preferential sputtering of Fe in EUROFER steel providing an in situ W surface and a potential first-wall solution for DEMO.« less

Plasma–wall interaction studies within the EUROfusion consortium: progress on plasma-facing components development and qualification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brezinsek, S.; Coenen, J. W.; Schwarz-Selinger, T.

The provision of a particle and power exhaust solution which is compatible with first-wall components and edge-plasma conditions is a key area of present-day fusion research and mandatory for a successful operation of ITER and DEMO. The work package plasma-facing components (WP PFC) within the European fusion programme complements with laboratory experiments, i.e. in linear plasma devices, electron and ion beam loading facilities, the studies performed in toroidally confined magnetic devices, such as JET, ASDEX Upgrade, WEST etc. The connection of both groups is done via common physics and engineering studies, including the qualification and specification of plasma-facing components, andmore » by modelling codes that simulate edge-plasma conditions and the plasma–material interaction as well as the study of fundamental processes. WP PFC addresses these critical points in order to ensure reliable and efficient use of conventional, solid PFCs in ITER (Be and W) and DEMO (W and steel) with respect to heat-load capabilities (transient and steady-state heat and particle loads), lifetime estimates (erosion, material mixing and surface morphology), and safety aspects (fuel retention, fuel removal, material migration and dust formation) particularly for quasi-steady-state conditions. Alternative scenarios and concepts (liquid Sn or Li as PFCs) for DEMO are developed and tested in the event that the conventional solution turns out to not be functional. Here, we present an overview of the activities with an emphasis on a few key results: (i) the observed synergistic effects in particle and heat loading of ITER-grade W with the available set of exposition devices on material properties such as roughness, ductility and microstructure; (ii) the progress in understanding of fuel retention, diffusion and outgassing in different W-based materials, including the impact of damage and impurities like N; and (iii), the preferential sputtering of Fe in EUROFER steel providing an in situ W surface and a potential first-wall solution for DEMO.« less