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: Oxygen isotope ratios were determined for quartz, magnetite, ankerite, siderite, riebeckite, hematite and talc in samples of banded iron-formation from the Dales Gorge Member of the Brockman Iron Formation.
218 citations
TL;DR: In this article, a good agreement was observed in the iron b-factors of metallic iron (a-Fe) and hematite calculated using both Mossbauer- and INRXS-derived data, which supports the validity and reliability of the calculations.
216 citations
TL;DR: It is demonstrated that Fe ions bound in the highly crystalline mineral magnetite are bioavailable as electron sinks and electron sources under varying environmental conditions, effectively rendering magnetite a naturally occurring battery.
Abstract: Microorganisms are a primary control on the redox-induced cycling of iron in the environment. Despite the ability of bacteria to grow using both Fe(II) and Fe(III) bound in solid-phase iron minerals, it is currently unknown whether changing environmental conditions enable the sharing of electrons in mixed-valent iron oxides between bacteria with different metabolisms. We show through magnetic and spectroscopic measurements that the phototrophic Fe(II)-oxidizing bacterium Rhodopseudomonas palustris TIE-1 oxidizes magnetite (Fe3O4) nanoparticles using light energy. This process is reversible in co-cultures by the anaerobic Fe(III)-reducing bacterium Geobacter sulfurreducens. These results demonstrate that Fe ions bound in the highly crystalline mineral magnetite are bioavailable as electron sinks and electron sources under varying environmental conditions, effectively rendering magnetite a naturally occurring battery.
216 citations
TL;DR: In this article, superparamagnetic polymeric nanofibers were produced via an electrospinning technique from colloidally-stable suspensions of magnetite nanoparticles in polyethylene oxide and polyvinyl alcohol solutions.
215 citations
01 Aug 2001
TL;DR: This preliminary study shows that the synthetic new material displays a behavior intermediate between that of magnetite and poly(DL-lactide) spheres, and the electron-donor component of the surface free energy of the solids is the quantity that appears to be most sensitive to the surface composition.
Abstract: A method for preparing colloidal particles formed by a magnetite nucleus and a biodegradable poly(DL-lactide) polymer coating is first described. The method is based on the so-called double-emulsion technique, employed to obtain polymeric spheres loaded with therapeutic drugs, to be used as drug delivery vectors. The aim of this work was to obtain, in a reproducible and rather simple way, colloidal particles that were both magnetic field responsive, and useful as drug delivery systems. In order to investigate to what extent is this target achieved, we compare the structure, chemical composition, and surface properties of the composite particles with those of the nucleus and the coating material. Although the surface properties of the magnetite core are not completely masked, this preliminary study shows that the synthetic new material displays a behavior intermediate between that of magnetite and poly(DL-lactide) spheres. Thus, electrophoresis measurements as a function of pH shows that the isoelectric point (pH(iep)=5.2) of core/shell colloids is in between those of magnetite (pH(iep)=7) and polymer (pH(iep)<2). A similar conclusion is reached when a surface thermodynamic study is performed on the three types of particles: the electron-donor component of the surface free energy of the solids is the quantity that appears to be most sensitive to the surface composition. The fact that poly(DL-lactide) is close to being a nonpolar material gives rise to a measurable decrease in the electron-donor component of the surface free energy, although the effect of coating is also observable in the electron-acceptor and the apolar van der Waals component. Copyright 2001 Academic Press.
215 citations