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Iowa State University

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Chemical Engineering

Magnetite

Publication Year

Articles 1 - 2 of 2

Full-Text Articles in Physics

Interfacial Properties And Iron Binding To Bacterial Proteins That Promote The Growth Of Magnetite Nanocrystals: X-Ray Reflectivity And Surface Spectroscopy Studies, Wenjie Wang, Wei Bu, Lijun Wang, Pierre E. Palo, Surya K. Mallapragada, Marit Nilsen-Hamilton, David Vaknin Jan 2012

Interfacial Properties And Iron Binding To Bacterial Proteins That Promote The Growth Of Magnetite Nanocrystals: X-Ray Reflectivity And Surface Spectroscopy Studies, Wenjie Wang, Wei Bu, Lijun Wang, Pierre E. Palo, Surya K. Mallapragada, Marit Nilsen-Hamilton, David Vaknin

Chemical and Biological Engineering Publications

Surface sensitive X-ray scattering and spectroscopic studies have been conducted to determine structural properties of Mms6, the protein in Magnetospirillum magneticum AMB-1 that is implicated as promoter of magnetite nanocrystals growth. Surface pressure versus molecular area isotherms indicate Mms6 forms stable monolayers at the aqueous/vapor interface that are strongly affected by ionic conditions of the subphase. Analysis of X-ray reflectivity from the monolayers shows that the protein conformation at the interface depends on surface pressure and on the presence of ions in the solutions, in particular of iron ions and its complexes. X-ray fluorescence at grazing angles of incidence ...


Magnetic Irreversibility And The Verwey Transition In Nanocrystalline Bacterial Magnetite, Ruslan Prozorov, Tanya Prozorov, Surya K. Mallapragada, Balaji Narasimhan, Timothy J. Williams, Dennis A. Bazylinski Jan 2007

Magnetic Irreversibility And The Verwey Transition In Nanocrystalline Bacterial Magnetite, Ruslan Prozorov, Tanya Prozorov, Surya K. Mallapragada, Balaji Narasimhan, Timothy J. Williams, Dennis A. Bazylinski

Chemical and Biological Engineering Publications

The magnetic properties of biologically produced magnetite nanocrystals biomineralized by four different magnetotactic bacteria were compared to those of synthetic magnetite nanocrystals and large, high-quality single crystals. The magnetic feature at the Verwey temperature TV was clearly seen in all nanocrystals, although its sharpness depended on the shape of individual nanoparticles and whether or not the particles were arranged in magnetosome chains. The transition was broader in the individual superparamagnetic nanoparticles for which TB < TV, where TB is the superparamagnetic blocking temperature. For nanocrystals organized in chains, the effective blocking temperature TB > TV and the Verwey transition is sharply defined. No correlation between particle size and TV was found. Furthermore, measurements of M (H,T,time) suggest that ...