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Coercive Force (coercive + force)
Selected AbstractsSynthesis and properties of ,-Fe2O3 nanorodsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2010R. Ramesh Abstract We report synthesis of ,-Fe2O3 (hematite) nanorods by reverse micelles method using cetyltrimethyl ammonium bromide (CTAB) as surfactant and calcined at 300 °C. The calcined ,-Fe2O3 nanorods were characterized by X-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM), transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM). The result showed that the ,-Fe2O3 nanorods were hexagonal structure. The nanorods have diameter of 30-50 nm and length of 120-150 nm. The weak ferromagnetic behavior was observed with saturation magnetization = 0.6 emu/g, coercive force = 25 Oe and remanant magnetization = 0.03 emu/g. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] FATHERS, SONS, AND THE STATE: Discipline and Punishment in a Wolof HinterlandCULTURAL ANTHROPOLOGY, Issue 1 2009DONNA L. PERRY ABSTRACT This essay builds on fieldwork in rural Senegal to examine three cases in which elder household heads called on gendarmes to physically discipline rebellious youths. These cases, which revolved around harsh acts of corporal punishment, invite inquiry into common assumptions about African families and states. The first assumption is the common dichotomy drawn between African youths, portrayed as modern and menacing, and African elders, portrayed as "traditional" and hence benign. The second assumption is the dichotomy drawn between the African family, conceived as solidary and nurturing, and the African state, conceived as alien and predatory. In examining these cases of discipline and punishment, this essay reveals the ever-shifting power relations that link Wolof household heads, dependent junior males, and state agents, and simultaneously introduces new questions about the morality of farmer,state relations and generational conflict. My analysis reveals the spatial geography of Senegal's youth crisis, which takes different forms in rural and urban locales. The anxiety of rural patriarchs is fed by a fear-mongering media obsessed with youthful anarchy in the cities, and a long-standing political rhetoric about the threat of rural out-migration. Elder men in the countryside, who experience diminishing household authority under neoliberalism, make proactive efforts to keep the urban youth crisis at bay. They seek to augment their domestic power by reestablishing links with a state that has long bolstered patriarchy but whose power is currently in decline. By lending patriarchs their coercive force, gendarmes attempt to accomplish through private, indirect means, what the postcolonial state is unable to do: maintain social order by reining in disruptive youths. The harsh disciplinary measures that gendarmes employ are not alien to Wolof culture, but integral to Wolof conceptions of child rearing. [source] High-Pressure Torsion for Giant Magnetoresistance and Better Magnetic Properties,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Shingo Nishihata High-pressure torsion (HPT) was conducted on Cu alloys containing ferromagnetic Co and Fe particles. Electron probe microanalysis, X-ray diffraction analysis, and transmission electron microscopy confirmed that the particles were significantly refined through fragmentation and some fractions were dissolved into the Cu matrix with straining by HPT. Saturation magnetization decreases with straining and coercive force increases with straining but they level off after intense straining. Magnetoresistance with an isotropic feature corresponding to giant magnetoresistance (GMR) appears at room temperature by processing with HPT. It is demonstrated that HPT is a potential process for controlling magnetic properties such as saturation magnetization and coercive force and also for creating GMR in the alloys prepared by conventional ingot metallurgy. [source] Bulk anisotropy Nd-Fe-B/,-Fe nanocomposite permanent magnets prepared by sonochemistry and spark plasma sinteringPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2007Peili Niu Abstract NdFeB/,-Fe nanocomposite magnetic powders were prepared by sonochemical process. The powders were then submitted to a hot press and subsequent hot deformation process by spark plasma sintering (SPS) technique. Effect of ,-Fe content on structure and magnetic properties of both isotropic and anisotropic magnets was investigated. For hot pressed magnets, the remanence increases with the content of ,-Fe, while the coercive force drops simultaneously. After hot deformation, the magnets with no more than 2 vol% ,-Fe exhibit obvious anisotropic characteristic. For the magnets with more ,-Fe, however, the magnetic anisotropy disappears due to the absence of (00l) crystal texture after deformation. It is, therefore, expected that ,-Fe content plays an important role in the formation of C-axis crystal texture during hot deformation process. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of film thickness on the electrical and magnetic properties of Co,Fe,Al,O filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2007M. H. Phan Abstract Influence of film thickness (t) on the electrical and magnetic properties of Co,Fe,Al,O films has been systematically investigated via means of vibrating sample magnetometry (VSM), permeability spectra and magneto-optical Kerr effect (MOKE). It is found that the electrical resistivity (,) decreases as the film thickness increases; , = 412.5 µ,cm for the t = 600 nm sample decreases to , = 368.2 µ,cm for the t = 1200 nm sample. The coercive force, measured along the easy-axis direction, decreases as the film thickness increases. Interestingly, along the hard-axis magnetization direction, the magnetic hysteresis loop is reversed and the coercive force is negative for the t = 600 and 800 nm samples. However, this peculiar feature disappears as t reaches 1200 nm, which is probably attributed to the microstructural change with respect to changes of film thickness. At a frequency of 1GHz, the hard-axis effective permeability decreases from 1252 to 1000 as the film thickness increases from 600 to 1200 nm, respectively. The VSM and MOKE results reveal an increase in magnetic anisotropy in the near-surface region of the film. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A Magnetically Separable Heterogeneous Deallylation Catalyst: [CpRu(,3 -C3H5)(2-pyridinecarboxylato)]PF6 Complex Supported on a Ferromagnetic Microsize Particle Fe3O4@SiO2EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2009Takuya Hirakawa Abstract The highly reactive and chemoselective homogeneousdeallylation catalyst CpRu(,3 -C3H5)(4-substituted-2-pyridinecarboxylato) was immobilized on microsize spherical Fe3O4@SiO2 particles. The resultant heterogeneous catalyst displays high saturation magnetization, weak coercive forces and high levels of dispersibility. The catalyst has increased the utility of deallylation by allowing the reaction to be conducted without extra additives. The only co-product of the reaction is a volatile allyl ether compound. Here, we demonstrate the efficient deallylation and separation of highly polar multifunctional compounds as well as multiple rounds of catalyst recycling without significant loss of reactivity. The usefulness of this catalyst has been confirmed by the synthesis of a triribonucleotide 3,5 U. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] | ||||||||||