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Magnetic Component (magnetic + component)
Selected AbstractsMagnetic Multi-Functional Nano Composites for Environmental ApplicationsADVANCED FUNCTIONAL MATERIALS, Issue 8 2009Jie Dong Abstract A novel concept is proposed to synthesize a new class of composites featuring magnetic, molecular sieve and metallic nanoparticle properties. These multi-functional materials have potential applications as recyclable catalysts, disinfectants and sorbents. The magnetic property enables effective separation of the spent composites from complex multiphase systems for regeneration and recycle, safe disposal of the waste and/or recovery of loaded valuable species. The zeolite molecular sieve provides a matrix which supports a remarkably new, simple, efficient and economical method to make stable, supported silver nanoparticles by silver ion exchange and controlled thermal reduction. The silver nanoparticles generated in this way have excellent properties such as high reactivity and good thermal stability without aggregation, which act as nano reactors for desired functionality in a wide range of applications. Magnetic component (Fe3O4), molecular sieve matrix (zeolite) and silver nanoparticles generated by ion exchange followed by controlled reduction, together form this unique novel composite with designed functions. It represents a practically operational, economical, sustainable and environmentally friendly new advanced functional material. This paper focuses on the novel synthesis and characterization of the composite, with an example of applications as sorbents for the removal of vapor-phase mercury from the flue gas of coal-fired power plants. [source] Magnetostratigraphic constraints on the Gondwanan origin of North China: Cambrian/Ordovician boundary resultsGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2002Zhenyu Yang Summary A significant gap in the middle Palaeozoic apparent polar wander (APW) path precludes polarity definition of the early Palaeozoic palaeopole for North China. This problem can in part be resolved by the intercontinental correlation of magnetic polarity patterns across small time intervals. A magnetostratigraphic study was carried out on upper Cambrian to lower Ordovician sediments near Zhaogezhuang (long. 118.5°E, lat. 39.7°N), North China. After stepwise thermal or thermal and alternating field demagnetizations, a characteristic magnetic component with normal and antipodal reversed directions was identified. These data, drawn from 49 samples, yield a north palaeopole at long. 294.6°E, lat. 32.9°N (dp = 3.0°, dm = 5.3°). A concordant magnetic polarity pattern around the Cambrian,Ordovician boundary and lowest Ordovician obtained from different continents favours a Southern Hemisphere origin (,17°) formation site. Using the Cambrian,Ordovician APW paths between North China and Gondwana, we suggest that the North China block (NCB) was part of Gondwana during the Cambro,lowest Ordovician, and started breaking away from Gondwana in the lower Ordovician. This finding is contrary to some palaeomagnetic models where the NCB was quite separate from Gondwana in the late Proterozoic, and was attached to the ,Pacific' side of Antarctica. [source] Guest-Induced Chirality in the Ferrimagnetic Nanoporous Diamond Framework Mn3(HCOO)6,ADVANCED FUNCTIONAL MATERIALS, Issue 4 2007B. Zhang Abstract Chiral magnets are obtained by inclusion of chiral guest molecules into the channels of an achiral nanoporous ferrimagnet consisting of the Mn3(HCOO)6 (1) framework. Insertion of the R or the S enantiomer of 2-chloropropan-1-ol (CH3C*HClCH2OH) in the chiral pores of the previously emptied framework (space group P21/c) results in the two corresponding chiral solids (1R and 1S, space group P21), while insertion of a racemic mixture of the two enantiomers retains the achirality of the host for the meso solid (1RS, space group P21/c). The R guest is ordered in the M channels while the S guest is ordered in the P channels. In contrast, the R guests in the P channels and the S guests in the M channels are disordered on two crystallographic orientations. For the racemic mixture of the two enantiomers in 1RS, random disorder of guests in both channels is observed. Thus, the localization of the guest molecule depends on the nature of the surface to recognize the guest of a particular chirality. The guest inclusion compounds are thermally stable. The 1R and 1S compounds are optically active. All the compounds adopt a ferrimagnetic ground state. Compared to the host framework of 1 without guest, the Curie temperature decreases for both 1R and 1S but increases for 1RS. The additional interactions between the framework and the inserted guest alcohols strengthen the lattice via hydrogen bonds and other electrostatic forces, and it might account for the significant lowering of the lattice contribution as well as the magnetic component to the specific heat capacity upon guest loading. [source] Multilayered Core/Shell Nanowires Displaying Two Distinct Magnetic Switching Events,ADVANCED MATERIALS, Issue 22 2010Yuen Tung Chong Atomic layer deposition (ALD) and electrodeposition are combined with a porous template to create ordered arrays of nanowires in which a nickel core and an iron oxide shell are separated by a silica spacer layer. The switching of each magnetic component is distinct and occurs at a field that depends on the tunable thicknesses of the various layers. [source] Discovery of 17 new sharp-lined Ap stars with magnetically resolved lines,MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008L. M. Freyhammer ABSTRACT Chemically peculiar A stars (Ap) are extreme examples of the interaction of atomic element diffusion processes with magnetic fields in stellar atmospheres. The rapidly oscillating Ap stars provide a means for studying these processes in three dimensions and are at the same time important for studying the pulsation excitation mechanism in A stars. As part of the first comprehensive, uniform, high-resolution spectroscopic survey of Ap stars, which we are conducting in the Southern hemisphere with the Michigan Spectral Catalogues as the basis of target selection, we report here the discovery of 17 new magnetic Ap stars having spectroscopically resolved Zeeman components from which we derive magnetic field moduli in the range 3,30 kG. Among these are (1) the current second strongest known magnetic A star, (2) a double-lined Ap binary with a magnetic component and (3) an A star with particularly peculiar and variable abundances. Polarimetry of these stars is needed to constrain their field geometries and to determine their rotation periods. We have also obtained an additional measurement of the magnetic field of the Ap star HD 92499. [source] Approximation of magnetic behavior of complex nanomagnetic materials, using the "P " curves for structural characterization of magnetic suspensionsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2008N. C. Popa Abstract The "P " curves for the structural characterization of magnetic nanoparticles suspensions (complex fluids, complex powders, complex composite materials, or living biological materials having magnetic properties) are the graphical representation of the first derivative (relative to the magnetic field strength H) of the magnetization curve relative to its saturation magnetization. In the case of the above materials, the magnetic properties are conferred to various carrier liquids by artificially integrating in their structure ferromagnetic particles of different sizes. The magnetic properties are usually shown by the hysteresis curve. The structure can be seen by (electronic) micrography. The P curves offer another possibility to determine the structure of the magnetic component of a complex fluid by numerical analysis of the magnetization curve experimentally obtained. Starting from these P curves, the paper presents the possibility to approximate the magnetic behavior of these complex nanomagnetic materials. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Investigation of field variation in multi-pole magnetic componentsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2007Kuo-Chi Chiu Abstract Using traditional methods, a fine magnetic pole pitch of less than 1 mm was very difficult to achieve and a complicated magnetization system was required. A linear wire circuit pattern was designed and formed on the printed circuit board (PCB) with a periodic structure, which provides a loop allowing the current to flow in opposite directions to induce different magnetic fields among the wire circuit. Correspondingly, a multi-pole magnetic component with a fine magnetic pole pitch of less than 1 mm was accomplished. Various multi-pole magnetic components with different pitch sizes of 400 ,m and 500 ,m were fabricated to investigate the field variation. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Magnetic quantification of urban pollution sources in atmospheric particulate matterGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2004S. Spassov SUMMARY A new method is presented for fast quantification of urban pollution sources in atmospheric particulate matter (PM). The remanent magnetization of PM samples collected in Switzerland at sites with different exposures to pollution sources is analysed. The coercivity distribution of each sample is calculated from detailed demagnetization curves of anhysteretic remanent magnetization (ARM) and is modelled using a linear combination of appropriate functions which represent the contribution of different sources of magnetic minerals to the total magnetization. Two magnetic components, C1 and C2, are identified in all samples. The low-coercivity component C1 predominates in less polluted sites, whereas the concentration of the higher-coercivity component C2 is large in urban areas. The same sites were monitored independently by Hüglin using detailed chemical analysis and a quantitative source attribution of the PM. His results are compared with the magnetic component analysis. The absolute and relative magnetic contributions of component C2 correlate very well with absolute and relative mass contributions of exhaust emissions, respectively. Traffic is the most important PM pollution source in Switzerland: it includes exhaust emissions and abrasion products released by vehicle brakes. Component C2 and traffic-related PM sources correlate well, which is encouraging for the implementation of non-destructive magnetic methods as an economic alternative to chemical analysis when mapping urban dust pollution. [source] First-order reversal curve diagrams and thermal relaxation effects in magnetic particlesGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2001Christopher R. Pike Summary We have recently developed a technique for characterizing the magnetic components within natural particle assemblages. This technique is based on the transformation of magnetization data from first-order reversal curves (FORCs) into contour plots of a 2-D distribution function (FORC diagrams). FORC diagrams are useful for obtaining information about switching fields and interactions in magnetic particle systems. Here, we examine experimental data and a theoretical model in order to provide a rigorous framework for interpreting FORC diagrams for samples that contain superparamagnetic particles. We have found four distinct manifestations of thermal relaxation on FORC diagrams. First, thermal relaxation will shift the FORC distribution to lower coercivities. Second, at intermediate temperatures, thermal relaxation can generate a secondary peak about the origin of a FORC diagram. This secondary peak indicates that part of a single-domain particle assemblage has become superparamagnetic. At high enough temperatures, the primary peak of the FORC distribution will be located about the origin of a FORC diagram. Third, thermal relaxation can produce a small, but systematic, upward shift of a FORC distribution. Fourth, thermal relaxation will produce contours that lie near and parallel to the vertical axis in the lower quadrant of a FORC diagram. These manifestations make FORC diagrams a powerful tool for studying the effects of thermal relaxation (superparamagnetism) in bulk natural samples, particularly when the samples contain mixed magnetic particle assemblages. [source] Magnetic grain-size distribution of the enhanced component in the loess,palaeosol sequences in the western Loess Plateau of ChinaGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2001Toshiaki Mishima SUMMARY Rock magnetic measurements of Chinese loess,palaeosol samples from the Beiyuan section in Linxia City suggest the presence of two magnetic components: a background component and an enhanced component. The magnetic properties of the enhanced component suggest strong grain-size control, which is in contrast with variable grain-size distribution in loess,palaeosol from the central Loess Plateau. Chemically formed magnetic grains do not fulfil the requirements in the case of the western Loess Plateau because they may show shifts in the grain-size distribution. The difference in climate between the western and central Loess Plateau may lead to different origins and different preservation conditions of the pedogenic magnetite. [source] Pacemaker Reed Switch Behavior in 0.5, 1.5, and 3.0 Tesla Magnetic Resonance Imaging Units: Are Reed Switches Always Closed in Strong Magnetic Fields?PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 10 2002ROGER LUECHINGER LUECHINGER, R., et al.: Pacemaker Reed Switch Behavior in 0.5, 1.5, and 3.0 Tesla Magnetic Resonance Imaging Units: Are Reed Switches Always Closed in Strong Magnetic Fields? MRI is established as an important diagnostic tool in medicine. However, the presence of a cardiac pacemaker is usually regarded as a contraindication for MRI due to safety reasons. The aim of this study was to investigate the state of a pacemaker reed switch in different orientations and positions in the main magnetic field of 0.5-, 1.5-, and 3.0-T MRI scanners. Reed switches used in current pacemakers and ICDs were tested in 0.5-, 1.5-, and 3.0-T MRI scanners. The closure of isolated reed switches was evaluated for different orientations and positions relative to the main magnetic field. The field strengths to close and open the reed switch and the orientation dependency of the closed state inside the main magnetic field were investigated. The measurements were repeated using two intact pacemakers to evaluate the potential influence of the other magnetic components, like the battery. If the reed switches were oriented parallel to the magnetic fields, they closed at 1.0 ± 0.2 mT and opened at 0.7 ± 0.2 mT. Two different reed switch behaviors were observed at different magnetic field strengths. In low magnetic fields (< 50 mT), the reed switches were closed. However, in high magnetic fields (> 200 mT), the reed switches opened in 50% of all tested orientations. No difference between the three scanners could be demonstrated. The reed switches showed the same behavior whether they were isolated or an integral part of the pacemakers. The reed switch in a pacemaker or an ICD does not necessarily remain closed in strong magnetic fields at 0.5, 1.5, or 3.0 T and the state of the reed switch may not be predictable with certainty in clinical situations. [source] Investigation of field variation in multi-pole magnetic componentsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2007Kuo-Chi Chiu Abstract Using traditional methods, a fine magnetic pole pitch of less than 1 mm was very difficult to achieve and a complicated magnetization system was required. A linear wire circuit pattern was designed and formed on the printed circuit board (PCB) with a periodic structure, which provides a loop allowing the current to flow in opposite directions to induce different magnetic fields among the wire circuit. Correspondingly, a multi-pole magnetic component with a fine magnetic pole pitch of less than 1 mm was accomplished. Various multi-pole magnetic components with different pitch sizes of 400 ,m and 500 ,m were fabricated to investigate the field variation. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||