Topic
Magnetite
About: Magnetite is a research topic. Over the lifetime, 10277 publications have been published within this topic receiving 278071 citations.
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TL;DR: Results indicate a ferrihydrite-magnetite core-shell structure and the presence of magnetite in the ferritin cores of patients with Alzheimer's disease is not a cause of their increased brain iron(II) concentration.
Abstract: Transmission Electron Microscopy (TEM), X-ray Absorption Near Edge Spectroscopy (XANES), Electron Energy-Loss Spectroscopy (EELS), Small-Angle X-ray Scattering (SAXS), and SQUID magnetic studies were performed in a batch of horse spleen ferritins from which iron had been gradually removed, yielding samples containing 2200, 1200, 500, and 200 iron atoms. Taken together, findings obtained demonstrate that the ferritin iron core consists of a polyphasic structure (ferrihydrite, magnetite, hematite) and that the proportion of phases is modified by iron removal. Thus, the relative amount of magnetite in ferritin containing 2200 to 200 iron atoms rose steadily from approximately 20% to approximately 70% whereas the percentage of ferrihydrite fell from approximately 60% to approximately 20%. These results indicate a ferrihydrite-magnetite core-shell structure. It was also found that the magnetite in the ferritin iron core is not a source of free toxic ferrous iron, as previously believed. Therefore, the presence of magnetite in the ferritin cores of patients with Alzheimer's disease is not a cause of their increased brain iron(II) concentration.
139 citations
TL;DR: In this paper, the authors investigated the characteristics of dissolution of iron oxides in oxalic acid and found that the dissolution rate increases with increasing oxalate concentration at the constant pH values set within the optimum range of pH2.5-3.0.
138 citations
TL;DR: In this article, the magnetic properties of magnetosomes in the freshwater magnetotactic bacterium Aquaspirillum magnetosum have been investigated and it was shown that the acquisition and demagnetization of various type of remanent magnetizations are markedly different for the two samples and suggest that remanence is substantially affected by magnetostatic interactions.
138 citations
TL;DR: In this article, a magnetite (Fe3O4) nanoparticle was synthesized using a solid state mechanochemical method and used for studying the sorption of uranium(VI) from aqueous solution onto the nanomaterial.
Abstract: Magnetite (Fe3O4) nanoparticle was synthesized using a solid state mechanochemical method and used for studying the sorption of uranium(VI) from aqueous solution onto the nanomaterial. The synthesized product is characterized using SEM, XRD and XPS. The particles were found to be largely agglomerated. XPS analysis showed that Fe(II)/Fe(III) ratio of the product is 0.58. Sorption of uranium on the synthesized nanomaterials was studied as a function of various operational parameters such as pH, initial metal ion concentration, ionic strength and contact time. pH studies showed that uranium sorption on magnetite is maximum in neutral solution. Uranium sorption onto magnetite showed two step kinetics, an initial fast sorption completing in 4–6 h followed by a slow uptake extending to several days. XPS analysis of the nanoparticle after sorption of uranium showed presence of the reduced species U(IV) on the nanoparticle surface. Fe(II)/Fe(III) ratio of the nanoparticle after uranium sorption was found to be 0.48, lower than the initial value indicating that some of the ferrous ion might be oxidized in the presence of uranium(VI). Uranium sorption studies were also conducted with effluent from ammonium diuranate precipitation process having a uranium concentration of about 4 ppm. 42% removal was observed during 6 h of equilibration.
138 citations
TL;DR: In this article, an experimental investigation has been made of the dependence of the coercive force on the density of some magnetite and gamma ferric oxide powders consisting of different sized and shaped particles.
Abstract: An experimental investigation has been made of the dependence of the coercive force on the density of some magnetite and gamma ferric oxide powders consisting of different sized and shaped particles. Various aspects of the data are discussed. In particular, an interpretation based on a calculation of the critical single domain size of iron oxide particles with a prolate spheroidal shape is consistent with the experimental results.
138 citations