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Full-Text Articles in Physical Sciences and Mathematics
A Comparison Of Magnetite Particles Produced Anaerobically By Magnetotactic And Dissimilatory Iron‐Reducing Bacteria, Bruce M. Moskowitz, Richard B. Frankel, Dennis A. Bazylinski, Holger W. Jannasch, Derek R. Lovley
A Comparison Of Magnetite Particles Produced Anaerobically By Magnetotactic And Dissimilatory Iron‐Reducing Bacteria, Bruce M. Moskowitz, Richard B. Frankel, Dennis A. Bazylinski, Holger W. Jannasch, Derek R. Lovley
Physics
We compare the magnetic properties of fine‐grained magnetite produced by two newly isolated anaerobic bacteria, a magnetotactic bacterium (MV‐1) and a dissimilatory iron‐reducing bacterium (GS‐15). Although room‐temperature magnetic properties are generally different between the two microorganisms, MV‐1 and GS‐15 magnetites can be most easily distinguished by the temperature variation of saturation remanence obtained at liquid helium temperatures. Magnetite produced by MV‐1 displays a sharp discontinuity in intensity at 100 K related to the Verwey transition. Magnetite produced by GS‐15 displays a gradual decrease in intensity with temperature due to the progressive unblocking of magnetization. The differing behavior is due exclusively …
Crystallochemical Characterization Of Magnetic Spinels Prepared From Aqueous Solution, Stephen Mann, Nicholas H.C. Sparks, Suzanne B. Couling, Miranda C. Larcombe, Richard B. Frankel
Crystallochemical Characterization Of Magnetic Spinels Prepared From Aqueous Solution, Stephen Mann, Nicholas H.C. Sparks, Suzanne B. Couling, Miranda C. Larcombe, Richard B. Frankel
Physics
The crystallochemical characterization of magnetic spinels prepared from aqueous solution has been studied primarily by electron microscopy and 57Fe Mossbauer spectroscopy. Two synthetic routes have been investigated : method 1 ; partial oxidation of Fe" solutions in the presence of NO; at 100 C , and method 2; reaction of hydrated Ferrr oxide (ferrihydrite) with Fe" ions at room temperature, pH = 7, 8 and 9. Both routes gave small (10-60 nm) irregular magnetite (Fe,O,) particles that were readily oxidised to maghemite (y-Fe,O,). The reaction proceeded via a green-rust intermediate and anions such as inorganic phosphate (Pi) and SO,,- …
Infrared Monitoring Of Nuclear Power In Space, David W. Hafemeister
Infrared Monitoring Of Nuclear Power In Space, David W. Hafemeister
Physics
This paper assesses the level of confidence for monitoring a ban on nuclear power in earth orbit using unclassified information from astronomical observatories based on Maui, Hawaii, and from the Kuiper Airborne Observatory. It is concluded that existing military and astronomical observatories can detect and identify operating nuclear reactor sources, such as the Soviet RORSAT and US SP-100, on satellites with a very high level of confidence out to distances beyond geosynchronous orbit. The smaller radioisotope thermal sources, RTG and DIPS, could be detected with a medium level of confidence under certain conditions.
Space Reactor Arms Control: Overview, Joel R. Primack, Nancy E. Abrams, Steven Aftergood, David W. Hafemeister, Daniel O. Hirsch, Robert Mozley, Oleg F. Prilutsky, Stanislav N. Rodionov, Roald Z. Sagdeev
Space Reactor Arms Control: Overview, Joel R. Primack, Nancy E. Abrams, Steven Aftergood, David W. Hafemeister, Daniel O. Hirsch, Robert Mozley, Oleg F. Prilutsky, Stanislav N. Rodionov, Roald Z. Sagdeev
Physics
Unshielded nuclear reactors provide the lightest and most survivable long-lived sources of electric power available to support military satellites. Restricting their use now, before a new generation of larger space reactors is tested and deployed by the US and USSR, could help prevent an arms race in space. Space nuclear power systems have been used by the United States and the Soviet Union since the 1960s. The Soviet Union has used orbiting nuclear reactors to power more than 30 radar ocean reconnaissance satellites (RORSATs). Two RORSATs have accidentally re-entered and released their radioactivity into the environment, and a third, Cosmos …