نتایج جستجو برای: Magnetite

تعداد نتایج: 5235  

2015
Zen-Wei Ouyang Erh-Chiang Chen Tzong-Ming Wu

This work describes the thermal stability and magnetic properties of polyvinylidene fluoride (PVDF)/magnetite nanocomposites fabricated using the solution mixing technique. The image of transmission electron microscopy for PVDF/magnetite nanocomposites reveals that the 13 nm magnetite nanoparticles are well distributed in PVDF matrix. The electroactive β-phase and piezoelectric responses of PVD...

2013
Tomohiro Iwasaki Ryo Nakatsuka Kenya Murase Hiroshige Takata Hideya Nakamura Satoru Watano

This paper presents a simple method for the rapid synthesis of magnetite/hydroxyapatite composite particles. In this method, superparamagnetic magnetite nanoparticles are first synthesized by coprecipitation using ferrous chloride and ferric chloride. Immediately following the synthesis, carbonate-substituted (B-type) hydroxyapatite particles are mechanochemically synthesized by wet milling dic...

2001
Shih-Bin Robin Chang Joseph Lynn Kirschvink

Magnetite Fe3O4 is one of the most stable carriers of natural remanent magnetization (NRM) in sedimentary rocks, and paleomagnetic studies of magnetite-bearing sediments, such as deep-sea cores and pelagic limestones, have provided a detailed calibration between the biostratigraphic and magnetic polarity time scales. Despite this important role, there is as yet a very poor understanding of how ...

2018
Soon-Hyeok Jeon Yeong-Ho Son Won-Ik Choi Geun Dong Song Do Haeng Hur

In nuclear power plants, the main corrosion product that is deposited on the outside of steam generator tubes is porous magnetite. The objective of this study was to simulate porous magnetite that is deposited on thermally treated (TT) Alloy 690 steam generator tubes. A magnetite layer was electrodeposited on an Alloy 690TT substrate in an Fe(III)-triethanolamine solution. After electrodepositi...

2016
Christopher Aaron Gorski

Magnetite (Fe3O4) is a commonly found in the environment and can form via several pathways, including biotic and abiotic reduction of Fe oxides and the oxidation of Fe and Fe. Despite extensive research, the redox behavior of magnetite is poorly understood. In previous work, the extent and kinetics of contaminant reduction by magnetite varied by several orders of magnitude between studies, two ...

2016
P. J. Vikesland R. L. Rebodos J. Y. Bottero

Magnetite nanoparticles are redox active constituents of subsurface and corrosive environments. In this study, we characterized the aggregation and sedimentation behavior of well characterized magnetite nanoparticle clusters using dynamic light scattering (DLS), UV-vis-NIR spectroscopy, and small angle X-ray scattering (SAXS). Both unfunctionalized (NaOH-magnetite) and tetramethylammonium hydro...

2017
Anneli Sundman James M Byrne Iris Bauer Nicolas Menguy Andreas Kappler

Humic substances (HS) are redox-active compounds that are ubiquitous in the environment and can serve as electron shuttles during microbial Fe(III) reduction thus reducing a variety of Fe(III) minerals. However, not much is known about redox reactions between HS and the mixed-valent mineral magnetite (Fe3O4) that can potentially lead to changes in Fe(II)/Fe(III) stoichiometry and even dissolve ...

2017
Hailiang Dong James K. Fredrickson David W. Kennedy John M. Zachara Ravi K. Kukkadapu Tullis C. Onstott

Ž . Although dissimilatory iron reducing bacteria DIRB are capable of reducing a number of metals in oxides and soluble forms, the factors controlling the raterextent of magnetite reduction and the nature of the mineral products resulting from magnetite reduction are not well understood. This study was carried out to investigate mechanisms and biogeochemical processes occurring during magnetite...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2004
Hojatollah Vali Benjamin Weiss Yi-Liang Li S Kelly Sears Soon Sam Kim Joseph L Kirschvink Chuanlun L Zhang

Distinct morphological characteristics of magnetite formed intracellularly by magnetic bacteria (magnetosome) are invoked as compelling evidence for biological activity on Earth and possibly on Mars. Crystals of magnetite produced extracellularly by a variety of bacteria including Geobacter metallireducens GS-15, thermophilic bacteria, and psychrotolerant bacteria are, however, traditionally no...

Journal: :Journal of hazardous materials 2010
Peng Yuan Dong Liu Mingde Fan Dan Yang Runliang Zhu Fei Ge JianXi Zhu Hongping He

Diatomite-supported/unsupported magnetite nanoparticles were prepared by co-precipitation and hydrosol methods, and characterized by X-ray diffraction, nitrogen adsorption, elemental analysis, differential scanning calorimetry, transmission electron microscopy and X-ray photoelectron spectroscopy. The average sizes of the unsupported and supported magnetite nanoparticles are around 25 and 15 nm...

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