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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: The first isolation and axenic culture of a marine magnetotactic bacterium, designated MV-1, that can synthesize intracellular, single-domain magnetite crystals under strictly anaerobic conditions was reported in this article.
Abstract: Bacterial production of magnetite represents a significant contribution to the natural remanent magnetism of deep-sea and other sediments1–5. Because cells of the freshwater magnetotactic bacterium Aquaspirillum magnetotacticum require molecular oxygen for growth and magnetite synthesis6, production of magnetite by magnetotactic bacteria has been considered to occur only in surficial aerobic sediments7. Moreover, it has been suggested that deposits of single-domain magnetite crystals are palaeooxygen indicators presumably having been formed under predominantly microaerobic conditions5–8. In contrast, some nonmagnetotactic, dissimilatory iron-reducing bacteria, such as the recently described strain GS-15 by Lovley et al.7, synthesize extracellular magnetite from hydrous ferric oxide under anaerobic conditions. We now report the first isolation and axenic culture of a marine, magnetotactic bacterium, designated MV-1, that can synthesize intracellular, single-domain magnetite crystals under strictly anaerobic conditions. We conclude that magnetotactic bacteria do not necessarily require molecular oxygen for magnetite synthesis and suggest that they, as well as dissimilatory iron-reducing bacteria, can contribute to the natural remanent magnetism of even long-term anaerobic sediments.
269 citations
TL;DR: In this article, the suitability of magnetite nanoparticles for adsorption of heavy metal cation and its efficiency was investigated by graft polymerization with acrylic acid, which was then used for separation of metal cations.
269 citations
Journal Article•
TL;DR: In this article, the authors studied the quaysfayalite-iron equilibria in the temperature range 1000-1400 and 1050-1300 K, respectively, using an electrochemical technique.
Abstract: The quartz-fayalite-iron and quartz-fayalite-magnetite equilibria have been studied in the temperature range 1000-1400 and 1050-1300 K, respectively, using an electrochemical technique. The results are in excellent agreement with the calorimetric data on fayalite (Robie et al., 1982). For magnetite, the results demonstrate conclusively that there is no zero-point entropy and that the earlier heat-content measurements of Coughlin et al. (1951) should be preferred to the measurements by differential scanning calorimetry of Gronvold and Sveen (1974) above the Curie point. For quartz-fayalite-iron,
268 citations
TL;DR: In this article, a mild-temperature, nonchemical technique is used to produce a nanohybrid multifunctional (electro-conducting and magnetic) powder material by intercalating iron oxide nanoparticles in large aspect ratio, open-ended, hollow-core carbon nanofibers (CNFs).
Abstract: A mild-temperature, nonchemical technique is used to produce a nanohybrid multifunctional (electro-conducting and magnetic) powder material by intercalating iron oxide nanoparticles in large aspect ratio, open-ended, hollow-core carbon nanofibers (CNFs). Single-crystal, superparamagnetic Fe3O4 nanoparticles (10 nm average diameter) filled the CNF internal cavity (diameter <100 nm) after successive steps starting with dispersion of CNFs and magnetite nanoparticles in aqueous or organic solvents, sequencing or combining sonication-assisted capillary imbibition and concentration-driven diffusion, and finally drying at mild temperatures. The influence of several process parameters—such as sonication type and duration, concentration of solids dispersed in solvent, CNF-to-nanoparticle mass ratio, and drying temperature—on intercalation efficiency (evaluated in terms of particle packing in the CNF cavity) was studied using electron microscopy. The magnetic CNF powder was used as a low-concentration filler in poly(methyl methacrylate) to demonstrate thin free-standing polymer films with simultaneous magnetic and electro-conducting properties. Such films could be implemented in sensors, optoelectromagnetic devices, or electromagnetic interference shields.
264 citations
TL;DR: In this paper, isolated rust layers have been investigated by electrochemical methods to find out whether their reduction and re-oxidation can affect the atmospheric corrosion of iron, and the results showed that the reduced surface layer can be easily oxidized back to γ-FeOOH, magnetite can partly be oxidized to Fe 2 O 3.
262 citations