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| Registros recuperados: 10 | |
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| Lins,Ulysses; McCartney,Martha R.; Farina,Marcos; Frankel,Richard B.; Buseck,Peter R.. |
| We report on the application of off-axis electron holography and high-resolution TEM to study the crystal habits of magnetosomes and magnetic microstructure in two coccoid morphotypes of magnetotactic bacteria collected from a brackish lagoon at Itaipu, Brazil. Itaipu-1, the larger coccoid organism, contains two separated chains of unusually large magnetosomes; the magnetosome crystals have roughly square projections, lengths up to 250 nm and are slightly elongated along [111] (width/length ratio of about 0.9). Itaipu-3 magnetosome crystals have lengths up to 120 nm, greater elongation along [111] (width/length ~0.6), and prominent corner facets. The results show that Itaipu-1 and Itaipu-3 magnetosome crystal habits are related, differing only in the... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Magnetite; Magnetotaxis; High-resolution transmission electron microscopy. |
| Ano: 2006 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652006000300007 |
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| Vilos,Cristian; Gutiérrez,Marlen; Escobar,Roberto A; Morales,Francisco; Denardin,Juliano C; Velasquez,Luis; Altbir,Dora. |
| Background: The progress in material science and the recent advances in biodegradable/biocompatible polymers and magnetic iron oxide nanoparticles have led to develop innovative diagnostic and therapeutic strategies for diseases based on multifunctional nanoparticles, which include contrast medium for magnetic resonance imaging, agent for hyperthermia and nanocarriers for targeted drug delivery. The aim of this work is to synthesize and characterize superparamagnetic iron oxide (magnetite), and to encapsulate them into poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanoparticles for biomedical applications. Results: The magnetite nanoparticles were confirmed by X-ray diffraction and exhibited a size of 22.3 ± 8.8 nm measured by transmission electron... |
| Tipo: Journal article |
Palavras-chave: Hyperthermia; Magnetic resonance image; Magnetite; PHBV; Polymeric nanoparticles. |
| Ano: 2013 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582013000500008 |
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| Passier, Hf; Dekkers, Mj. |
| Low-temperature magnetic properties of eastern Mediterranean sediments from a box-core have been investigated. This box-core contains the present-day oxic-suboxic boundary that is situated at the top of the relic of the youngest sapropel (S1). The upper half of sapropel S1 has been oxidized, and Fe oxides have precipitated in the oxidized sapropel. Zero-field-cooling (ZFC) and field-cooling (FC) saturation remanent magnetization (M-r; induced in a field of 2.5 T at 20 K after cooling from 300 K with or without the 2.5 T field) was measured during warming to 300 K. An M (r) imparted at room temperature (RTSIRM) was cycled to 20 K as well. The difference between ZFC and FC curves around the Verwey transition, as estimated by the parameter delta(FC)... |
| Tipo: Text |
Palavras-chave: Geochemistry; Low-temperature magnetism; Magnetite; Marine sediments; Oxidation; Sediment magnetism. |
| Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00223/33399/31887.pdf |
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| Passier, Hf; De Lange, Gj; Dekkers, Mj. |
| Magnetic properties (IRM, ARM, chi (in), S-ratio at 0.3 T, room temperature (RT) hysteresis and thermomagnetic curves) and geochemical data (Fe, S, Mn, Al, Ti, organic C) were studied in two eastern Mediterranean boxcores (ABC26 and BC19) at a resolution of 3-5 mm. The boxcores contain sapropel S1 (9-6 kyr BP) at a few decimetres below seafloor. The magnetic fraction consists predominantly of single-domain (SD) to pseudo-single-domain (PSD) magnetite in the entire cores. The original input of magnetic grains comes from two sources: aeolian dust (both cores) and volcanic ash from the Minoan eruption of Santorini (core BC19 only). Non-steady-state diagenesis has changed the magnetic mineralogy considerably in these alternating organic-rich /organic-poor... |
| Tipo: Text |
Palavras-chave: Geochemistry; Magnetite; Marine sediments; Mediterranean Sea; Oxidation; Sediment magnetism. |
| Ano: 2001 |
URL: https://archimer.ifremer.fr/doc/00221/33184/31805.pdf |
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| Bouilloux, Alexandra; Valet, Jean-pierre; Bassinot, Franck; Joron, Jean-louis; Blanc-valleron, Marie-madeleine; Moreno, Eva; Dewilde, Fabien; Kars, Myriam; Lagroix, France. |
| Large changes in magnetic mineral concentration dependent parameters by more than 1 order of magnitude occur over 50-150 cm intervals in two marine sediment cores from the oxygen minimum zone in the Gulf of Aden. High-resolution sedimentological and chemical analyses indicate that these intervals are not associated with turbiditic events or sediment reworking, they do not result from changes in carbonate dilution or differences in sediment properties, and they do not correspond to volcanic layers. Magnetic mineralogical analyses reveal a change in magnetic mineral concentration from a magnetite-goethite assemblage to pure magnetite within the peak. The peaks almost disappear when the abundance of magnetic minerals is calculated after correcting for the... |
| Tipo: Text |
Palavras-chave: Paleomagnetism; Paleoenvironment; Goethite; Magnetite; Indian ocean. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00264/37488/36828.pdf |
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| Silva Filho,Luiz Aníbal; Ker,João Carlos; Fontes,Maurício Paulo Ferreira; Camêlo,Danilo de Lima; Corrêa,Marcelo Metri; Cavalcante,Luis Carlos Duarte; Guimarães,Luciano de Moura. |
| ABSTRACT Ferrimagnetic Fe-oxides are important soil components, which are present in most of the agricultural soils of Brazil. Distinction, origin, and assessment of the influence of these minerals on magnetism and geochemistry is a challenge for mineralogists. This study aimed to characterize mineralogically Fe-rich Rhodic Oxisols ( Latossolos Vermelhos ) originating from several mafic rocks in Brazil, and assess the implications on their magnetic and geochemical properties. We present results on magnetic measurements, chemical dissolutions, X-ray diffractometry, Rietveld refinement, Raman, and Mössbauer spectroscopies of Fe-rich Rhodic Oxisols originating from several mafic rocks. They show that magnetite is inherited from the parent material, and its... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Magnetite; Maghemite; Trace elements; Mafic rocks; Raman spectroscopy. |
| Ano: 2019 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832019000100411 |
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| Registros recuperados: 10 | |
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