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Series

California Polytechnic State University, San Luis Obispo

1991

Articles 1 - 10 of 10

Full-Text Articles in Physics

Variation Of Superparamagnetic Properties With Iron Loading In Mammalian Ferritin, Richard B. Frankel, G. C. Papaefthymiou, G. D. Watt Nov 1991

Variation Of Superparamagnetic Properties With Iron Loading In Mammalian Ferritin, Richard B. Frankel, G. C. Papaefthymiou, G. D. Watt

Physics

The average blocking temperatures of ferritin molecules containing differing amounts of iron were determined by Mossbauer spectroscopy. The results imply that the magnetic anisotropy of the ferritin core particles is a function of particle volume. By addition of 57Fe to ferritin core particles it was determined that, at a given temperature within the superpara-magnetic temperature region, the “last-in” ferric ions have average relaxation times that are shorter than those of the bulk ferric ions.


Inorganic Particles Produced By Microorganisms, Richard B. Frankel Oct 1991

Inorganic Particles Produced By Microorganisms, Richard B. Frankel

Physics

The processes by which microorganisms, particularly bacteria, produce inorganic mineral particles are reviewed.


Structure, Morphology And Growth Of Biogenic Greigite (Fe3S4), Brigid R. Heywood, Stephen Mann, Richard B. Frankel Oct 1991

Structure, Morphology And Growth Of Biogenic Greigite (Fe3S4), Brigid R. Heywood, Stephen Mann, Richard B. Frankel

Physics

Several species of aquatic bacteria are known to exploit the earth's geomagnetic field as a means of directing their motion towards suitable habitats. A feature common to these bacteria is the presence of discrete intracellular magnetic inclusions, magnetosomes, aligned in chains along the long axis of the organism. The size and orientation of the individual magnetic particles imparts a permanent magnetic dipole moment to the cell which is, in turn, responsible for the magnetotactic response. In all species examined to date the magnetic particles have been found to be well-ordered, single domain, membrane-bounded crystals with reproducible, species-specific morphologies. Until ...


Paper Or Plastic?, Matthew J. Moelter Sep 1991

Paper Or Plastic?, Matthew J. Moelter

Physics

Letter to the Editor.


Intercellular Junctions, Motility, And Magnetosome Structure In A Multicellular Magnetotactic Prokaryote, Frank G. Rodgers, Richard P. Blakemore, Nancy A. Blakemore, Richard B. Frankel, Dennis A. Bazylinski, Denise Maratea, Christine Rodgers Mar 1991

Intercellular Junctions, Motility, And Magnetosome Structure In A Multicellular Magnetotactic Prokaryote, Frank G. Rodgers, Richard P. Blakemore, Nancy A. Blakemore, Richard B. Frankel, Dennis A. Bazylinski, Denise Maratea, Christine Rodgers

Physics

A many-celled, magnetotactic, prokaryote obtained from brackish water possessed intercellular connections at points of contact between the outer membranes of constituent cells. These connections structurally resembled the "gap junctions" found in eukaryotes. Each aggregate organism consisted of 10 to 30 individual gram-negative cells containing material with the appearance of poly-𝛽-hydroxybutyrate and magnetosomes of unusual arrangement, structure and composition. The aggregate, which possessed prokaryotic-type flagella arranged at the outward surfaces of each cell, showed motility indicative of coordination between individual component cells. These results suggest that this organism is a multicellular prokaryote.


Biomineralization Of Iron Sulfides In Magnetotactic Bacteria From Sulfidic Environments, Dennis A. Bazylinski, Richard B. Frankel, Anthony J. Garratt-Reed, Stephen Mann Mar 1991

Biomineralization Of Iron Sulfides In Magnetotactic Bacteria From Sulfidic Environments, Dennis A. Bazylinski, Richard B. Frankel, Anthony J. Garratt-Reed, Stephen Mann

Physics

No abstract provided.


Iron Biominerals: An Overview, Richard B. Frankel Mar 1991

Iron Biominerals: An Overview, Richard B. Frankel

Physics

No abstract provided.


Redox Capacity Of Apo Mammalian Ferritin, Gerald D. Watt, Richard B. Frankel Mar 1991

Redox Capacity Of Apo Mammalian Ferritin, Gerald D. Watt, Richard B. Frankel

Physics

No abstract provided.


Magnetic Fine Particles In Biological Systems, Dominic P.E. Dickson, Richard B. Frankel Jan 1991

Magnetic Fine Particles In Biological Systems, Dominic P.E. Dickson, Richard B. Frankel

Physics

Two examples of biological magnetic fine particles are considered: iron-storage proteins and magnetotactic bacteria. These cover many aspects of this field, including the use of well-defined biological systems for testing theoretical models, using magnetic properties to distinguish between different biological materials, producing magnetic materials by biological processes, and using optimised biological magnetic systems as a guide to the production of synthetic magnetic materials.


Electronic Properties Of Monocapped Prismane And Basket Iron-Sulphur Clusters, B. S. Snyder, M. S. Reynolds, R. H. Holm, G. C. Papaefthymiou, R. B. Frankel Jan 1991

Electronic Properties Of Monocapped Prismane And Basket Iron-Sulphur Clusters, B. S. Snyder, M. S. Reynolds, R. H. Holm, G. C. Papaefthymiou, R. B. Frankel

Physics

The ground state electronic properties of the mixed-valence clusters Fe7S6 (PEt3)4Cl3 (1), Fe6S6(PEt3)4L2 [L = Cl− (2), Br− (4), I− (5) and PhS− (6)], Fe6Se6 (PEt3)4Cl2 (3) and [Fe6S6(PEt)6]1− (9), have been investigated by magnetic susceptibility, magnetization and Mössbauer spectroscopic measurements. Cluster 1 has a (idealized C3v) monocapped prismane structure and clusters 2–6 and 9 adopt the C2v “basket” configuration based on the [Fe62-S)(μ3 ...