Physics Commons^™

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

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 culture^3,4. 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

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

Physics

No abstract provided.

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.

Biomineralizationof Fe3O4 In Bacteria, R. B. Frankel, G. C. Papaefthymiou

Physics

No abstract provided.

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.

Magnetic Phase Transition, Aggregate Formation, And Electrical Conductivity In Fecl3-Doped Polyacetylene, E. K. Sichel, M. F. Rubner, J. Georger, Jr., G. C. Papaefthymiou, S. Offer, Richard B. Frankel

Physics

Both Fe³⁺ and Fe²⁺ ions occur in FeCl₃-doped polyacetylene. At low dopant levels (2+ and Fe³⁺ ions are paramagnetic down to 4.2 K. At dopant levels >0.01 mole fraction, there is evidence from Mössbauer spectroscopy that Fe²⁺ ions associate into aggregates which are magnetically ordered below 25 K. Aggregate formation appears to correlate with high electrical conductivity.

Search For Fractional Charges Produced In Heavy-Ion Collisions At 1.9 Gev/Nucleon, Michael A. Lindgren, David C. Joyce, Peter C. Abrams, Roger W. Bland, Robert T. Johnson, Tanya D. Knoop, Maureen H. Savage, Marion H. Scholz, Betty A. Young, Christopher L. Hodges, Alan A. Hahn, Gordon L. Shaw, Klaus S. Lackner, Howel G. Pugh, Richard Slansky

Physics

An experiment was performed to capture fractionally charged particles produced in heavy-ion collisions and to concentrate them in samples suitable for analysis by various techniques. Two of the samples so produced have been searched, with use of an automated version of Millikan's oil-drop apparatus. The beam was ⁵⁶Fe at 1.9 GeV/nucleon, incident on a lead target. Less than one fractional charge per 1.0× 10⁴ Fe-Pb collisions was found to be produced, and, with further assumptions, less than one per 2.0× 10⁶ collisions.

Fe3O4 Precipitation In Magnetotactic Bacteria, Richard B. Frankel, Georgia C. Papaefthymiou, Richard P. Blakemore, Wendy O'Brien

Physics

Using Mössbauer resonance spectroscopy of ⁵⁷Fe, we have determined the nature and distribution of major iron compounds in the magnetotactic bacterium Aquaspirillum magnetotacticum. In addition to magnetite (Fe₃O₄), cells contained a low-density hydrous ferric oxide, a high-density hydrous ferric oxide (ferrihydrite), and ferrous iron. Analysis at different temperatures of whole cells harvested early and late in growth, of mutant cells unable to synthesize magnetite, and of cell fractions enriched in ⁵⁷Fe indicated that Fe₃O₄ precipitation resulted from partial reduction of the high-density hydrous ferric oxide precursor.

Search For Fractional Charges In Water, David C. Joyce, Peter C. Abrams, Roger W. Bland, Robert T. Johnson, Michael A. Lindgren, Maureen H. Savage, Marion H. Scholz, Betty A. Young, Christopher L. Hodges

Physics

Results are presented from a search for fractional charges in water from a variety of natural sources. About 30 000 water drops have been measured, comprising 51 μg of water and dissolved materials. No evidence for fractional charge was seen.

Science And Society Test Viii: The Arms Race Revisited, David W. Hafemeister

Physics

Approximate numerical estimates are developed in order to quantify a variety of aspects of the arms race. The results of these calculations are consistent with either direct observations or with more sophisticated calculations. This paper will cover some of the following aspects of the arms race: (1) the electromagnetic pulse (EMP); (2) spy satellites; (3) ICBM accuracy; (4) NAVSTAR global positioning satellites; (5) particle and laser beam weapons; (6) the neutron bomb; and (7) war games.

Interactive Computer Graphics: The Arms Race, David W. Hafemeister

Physics

No abstract provided.

A Chronology Of The Nuclear Arms Race, David W. Hafemeister

Physics

No abstract provided.

Basic Physics Of Emp, Beam Weapons, And Abm, David W. Hafemeister

Physics

No abstract provided.

Iron-Containing Cells In The Honey Bee (Apis Mellifera), Deborah A. Kuterbach, Benjamin Walcott, Richard J. Reeder, Richard B. Frankel

Physics

Honey bees are sensitive to earth strength magnetic fields and are reported to contain magnetite (Fe₃O₄) in their abdomens. We report bands of cells around each abdominal segment that contain numerous electron-opaque, iron-containing granules. The iron is principally in the form of hydrous iron oxides.

Birefringence Determination Of Magnetic Moments Of Magnetotactic Bacteria, Charles Rosenblatt, F. F. Torres De Araujo, Richard B. Frankel

Physics

A birefringence technique is used to determine the average magnetic moments of magnetotactic bacteria in culture. Differences in are noted between live and dead bacteria, as well as between normal density and high density samples of live bacteria.

Fe Hyperfine Fields In Fe3-XVXSi Alloys, T. J. Burch, C. A. Weiler, K. Raj, J. I. Budnick, V. Niculescu, G. C. Papaefthymiou, Richard B. Frankel

Physics

The Mössbauer spectra of Fe in Fe_3-xV_xSi alloys for 0≤x≤1 shows that V occupies almost exclusively one of two Fe sites (the B site). As x increases the spectra of Fe on the other site (the A, C site) becomes increasingly complex as the number of their V 1st neighbors increases. Simulated Mössbauer spectra were calculated using moments obtained by a simple model from bulk magnetization and V NMR data. This model assumes a decrease in Fe(A, C) moments as the number of their Fe 1st neighbors decreases. Comparison of the Fe(B) field of the alloy …

Light Scattering Determination Of Magnetic Moments Of Magnetotactic Bacteria (Invited), Charles Rosenblatt, F. F. Torres De Araujo, Richard B. Frankel

Physics

Light scattering is used to determine the average lengths and magnetic moments of magnetotactic bacteria in culture. The results are consistent with estimates made from electron micrographs.

The Electronic Controls Used In A Search For Fractional Charges In Mercury Drops, William Walters, David C. Joyce, Peter C. Abrams, K. R. Koburn, Betty A. Young

Physics

At San Francisco State University, we have developed an Automatic Millikan Device (AMI)) for measuring the charge on small drops of Mercury. The device uses a standard atomic physics laboratory Millikan chamber, a piezoelectric driven ink-jet glass dropper, and a laser-photomultiplier system for tracking the motion of the drop. This paper describes the electronic control and error detection system used with the AMO. Signals from this system are sent to a microprocessor which controls the experiment. To this date (Dec 7, 1981), we have measured 175 micrograms of Hg and found no fractional charges in 1.05 x 10²⁰ nucleons.

Magnetotactic Bacteria, Richard B. Frankel

Physics

No abstract provided.

Magnetotactic Bacteria At The Geomagnetic Equator, Richard B. Frankel, R. P. Blakemore, F. F. Torres De Araujo, D. M. S. Esquivel, J. Danon

Physics

Magnetotactic bacteria are present in fresh water and marine sediments of Fortaleza, Brazil, situated close to the geomagnetic equator. Both South-seeking and North-seeking bacteria are present in roughly equal numbers in the same samples. This observation is consistent with the hypothesis that the vertical component of the geomagnetic field selects the predominant polarity type among magnetotactic bacteria in natural environments.

Mossbauer Spectroscopy Of Iron-Containing Dermal Granules From Molpadia Intermedia, S. Ofer, G. C. Papaefthymiou, R. B. Frankel, H. A. Lowenstam

Physics

Dermal granules containing hydrous ferric oxide cores from Molpadia intermedia were studied by Mössbauer spectroscopy from 1.5 t0 300 K and in magnetic fields up to 80 kOersted at 4.2 K. A magnetic phase transition to an antiferromagnetically ordered state is observed at 10 K. The results are compared with the magnetic behavior of micellar cores of ferritin from eukaryotes and iron-storage materials from prokaryotes.

Study Of Iron In Magnetotactic Bacteria, Richard B. Frankel, Richard P. Blakemore

Physics

Bacteria have recently been discovered directing their movements by sensing the earth's magnetic field. They contain arrays of crystals of lodestone or magnetite which they synthesize from iron in the ocean. The discovery of the same type of crystals in the abdomens of honey bees and the brains of homing pigeons suggests that nature is not oblivious to the earth's magnetic field. The biological mechanism for sensing magnetic fields has never been determined. These bacteria are capable of biologically synthesizing highly purified single domain magnets that would be very expensive to produce chemically.

The tiny perfect magnetite crystals made by …

Bulk Magnetic Properties Of Magnetotactic Bacteria, C. R. Denham, R. P. Blakemore, Richard B. Frankel

Physics

Bulk magnetization measurements at room temperature of freeze dried magnetotactic bacterial cells, nonmagnetotactic bacterial cells, and extracted magnetosomes from magnetotactic cells are presented. The role of the magnetosome in the magnetotactic response of swimming cells is discussed.

South-Seeking Magnetotactic Bacteria In The Southern Hemisphere, R. P. Blakemore, Richard B. Frankel, Ad. J. Kalmijn

Physics

Several species of aquatic bacteria which orient in the Earth's magnetic field and swim along magnetic field lines in a preferred direction (magnetotaxis) have been observed in marine and freshwater sediments of the Northern Hemisphere^1,2. Their orientation is due to one or more intracytoplasmic chains of single-domain magnetite particles³. These linearly arranged particles impart a net magnetic dipole moment to the bacterium, parallel to the axis of motility. Northern Hemisphere magnetotactic bacteria with unidirectional motility swim consistently in the direction of the magnetic field, that is, to the geomagnetic North^1,2,4. This implies that their …

Nature Of Iron Deposits On The Cardiac Walls In Β-Thalassemia By Mössbauer Spectroscopy, K. S. Kaufman, G. C. Papaefthymiou, Richard B. Frankel, A. Rosenthal

Physics

An identification of the nature and an estimation of the particle size distribution of the iron deposits on thalassemic heart tissue is carried out by variable temperature Mössbauer spectroscopy. Comparison of Mössbauer spectra obtained for the thalassemic heart tissue (I) with those of normal heart tissue (II) and of horse spleen ferritin (III) identifies the iron deposits to be small, superparamagnetic particles of ferritin and/or hemosiderin, two closely related iron storage proteins containing an iron core of (FeOOH)₈(FeO · OPO₃H₂). The dependence of the superparamagnetic relaxation time, τ₂, of magnetically ordered fine …

Electronic Properties Of Molybdenum-Iron-Sulfur-Clusters: Approaches To The Molybdenum Site In Nitrogenase, Richard B. Frankel, T. E. Wolff, P. P. Power, R. H. Holm

Physics

No abstract provided.

Navigational Compass In Magnetic Bacteria, Richard B. Frankel, R. P. Blakemore

Physics

Magnetotactic bacteria that orient and swim in a preferred direction in the geomagnetic field contain sufficient single domain magnetite to constitute a biomagnetic compass.

Magnetic Properties Of [Fe4S4(Sr)4]3- Clusters, G. C. Papaefthymiou, Richard B. Frankel, S. Foner, E. J. Laskowski, R. H. Holm

Physics

No abstract provided.