Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 7 of 7
Full-Text Articles in Physics
Statement Of Dr. David Hafemeister Regarding The Need To Convert Domestic Research Reactors From Highly Enriched To Low-Enriched Uranium Fuels, David W. Hafemeister
Statement Of Dr. David Hafemeister Regarding The Need To Convert Domestic Research Reactors From Highly Enriched To Low-Enriched Uranium Fuels, David W. Hafemeister
Physics
No abstract provided.
Structure, Morphology And Crystal Growth Of Bacterial Magnetite, Stephen Mann, Richard B. Frankel, Richard P. Blakemore
Structure, Morphology And Crystal Growth Of Bacterial Magnetite, Stephen Mann, Richard B. Frankel, Richard P. Blakemore
Physics
Recent high-resolution transmission electron microscopy (HRTEM) studies of the structure and morphology of bacterial magnetite (Fe3O4) crystals isolated from a magnetotactic coccus1 and from an unidentified bacterium extracted from sediment2 have shown the crystals to be well ordered single-domain particles with a morphology based on a hexagonal prism of {011} faces truncated by specific low index planes. We report here a HRTEM study of intact magnetite crystals (magnetosomes) in the microaerophilic bacterium Aquaspirillum magnetotacticum, grown in pure culture3,4. Our aim has been to investigate the structure, morphology and crystal growth of …
Magnetosome Dynamics In Magnetotactic Bacteria, S. Ofer, I. Nowik, E. R. Bauminger, G. C. Papaefthymiou, Richard B. Frankel, Richad P. Blakemore
Magnetosome Dynamics In Magnetotactic Bacteria, S. Ofer, I. Nowik, E. R. Bauminger, G. C. Papaefthymiou, Richard B. Frankel, Richad P. Blakemore
Physics
Diffusive motions of the magnetosomes (enveloped Fe3O4 particles) in the magnetotactic bacterium Aquaspirillum magnetotacticum result in a very broad-line Mössbauer spectrum (T ~ 100 mm/s) above freezing temperatures. The line width increases with increasing temperature. The data are analyzed using a bounded diffusion model to yield the rotational and translational motions of the magnetosomes as well as the effective viscosity of the material surrounding the magnetosomes. The results are <θ2>l/2 < 1.5° and <x2>1/2 < 8.4 Å for the rotational and translational motions, respectively, implying that the particles are fixed in whole cells. The effective viscosity is 10 cP at 295 K and increases with decreasing temperature. Additional Fe3+ material in the cell is shown to be associated with the magnetosomes. Fe2+ material in the cell appears to be …
Magnetic Guidance Of Organisms, Richard B. Frankel
Precipitation Of Fe3O4 In Magnetotactic Bacteria, Richard B. Frankel, Richard P. Blakemore
Precipitation Of Fe3O4 In Magnetotactic Bacteria, Richard B. Frankel, Richard P. Blakemore
Physics
The magnetotactic bacterium A. magnetotacticum contains ferrous ions, a low density hydrous ferric oxide, a high density hydrous ferric oxide (ferrihydrite) and Fe3O4, which is precipitated by partial reduction of the ferrihydrite precursor.
The Feasibility Of The X-Ray Laser Pumped With A Nuclear Explosion, David W. Hafemeister
The Feasibility Of The X-Ray Laser Pumped With A Nuclear Explosion, David W. Hafemeister
Physics
Recent reports have indicated that an x-ray laser pumped with a nuclear explosion at a wavelength of 1.4nm (0.9 keV) has made some initial progress. It has been proposed to extend the development of this device to establish it as part of a layered ballistic missile defensive system to protect the United States against a nuclear attack. This paper will discuss the following aspects on the feasibility of this system: (1) Conditions affecting the efficiency of the X-ray laser; (2) Angular resolution and size of.the laser rods; (3) Energy on targets; (4) Basing Modes; (5) Countermeasures; and (6) Legal constraints.
Biomineralizationof Fe3O4 In Bacteria, R. B. Frankel, G. C. Papaefthymiou
Biomineralizationof Fe3O4 In Bacteria, R. B. Frankel, G. C. Papaefthymiou
Physics
No abstract provided.