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Articles 841 - 870 of 968

Full-Text Articles in Physics

Anomalous Magnetic Properties Of Some High-Temperature Magnetic Superconductors, P. H. Hor, R. L. Meng, C. W. Chu, C. Y, Huang, R, B. Frankel Jan 1988

Anomalous Magnetic Properties Of Some High-Temperature Magnetic Superconductors, P. H. Hor, R. L. Meng, C. W. Chu, C. Y, Huang, R, B. Frankel

Physics

No abstract provided.


Magnetite And Magnetotaxis In Microorganisms, Richard B. Frankel, R. P. Blakemore Jan 1988

Magnetite And Magnetotaxis In Microorganisms, Richard B. Frankel, R. P. Blakemore

Physics

No abstract provided.


Bacterial Biomagnetism And Geomagnetic Field Detection By Organisms, Richard P. Blakemore, Nancy A. Blakemore, Richard B. Frankel Jan 1988

Bacterial Biomagnetism And Geomagnetic Field Detection By Organisms, Richard P. Blakemore, Nancy A. Blakemore, Richard B. Frankel

Physics

No abstract provided.


Preparation, Crystal Structure, And Physical Properties Of A Pyrogallol-Bridged Vanadium(Iii) Complex, Seunghee Lee, Koji Nakanishi, Michael Y. Chiang, Richard B. Frankel, K. Spartalian Jan 1988

Preparation, Crystal Structure, And Physical Properties Of A Pyrogallol-Bridged Vanadium(Iii) Complex, Seunghee Lee, Koji Nakanishi, Michael Y. Chiang, Richard B. Frankel, K. Spartalian

Physics

The structure, n.m.r. spectrum, and magnetic properties of the vanadium(III) dimer [(acac)4V2{µ-OC6H3(OH)2}2] formed from [VO(acac)2] and an excess of pyrogallol are described.


Observation Of Substitutional Site Preference In A Quasicrystal And Implication On Local Structure, M. Eibschütz, M. E. Lines, H. S. Chen, J. V. Waszczak, G. C. Papaefthymiou, Richard B. Frankel Nov 1987

Observation Of Substitutional Site Preference In A Quasicrystal And Implication On Local Structure, M. Eibschütz, M. E. Lines, H. S. Chen, J. V. Waszczak, G. C. Papaefthymiou, Richard B. Frankel

Physics

A combination of magnetic susceptibility and Mössbauer measurements on quasicrystalline i-Al74Mn20-xFexSi6 (0.02≤x≤7.5) establishes that Mn atoms in i-Al74Mn20Si6 occupy two distinct classes of sites, and that Fe substitutes for only one of them. The two classes are distinguished by the possession or otherwise of a localized magnetic moment. The data are consistent with a structure of interconnecting Mackay icosahedra (MI) in which localized moments are possessed only by Mn atoms adjacent to "broken" MI connections. The implied connectivity of the resulting MI network is close to …


Anaerobes Pumping Iron, Richard B. Frankel Nov 1987

Anaerobes Pumping Iron, Richard B. Frankel

Physics

No abstract provided.


Observation Of Possible Supercondictivity At 230 K, C. Y. Huang, L. J. Dries, P. H. Hor, R. L. Meng, C. W. Chu, Richard B. Frankel Jul 1987

Observation Of Possible Supercondictivity At 230 K, C. Y. Huang, L. J. Dries, P. H. Hor, R. L. Meng, C. W. Chu, Richard B. Frankel

Physics

Recently, Chu announced the observation of sharp drops of up to two orders of magnitude in the resistance of several Y-, Sc- and La-based multi-phase Ba–Cu oxide samples at temperatures as high as 240 K. The resistance drops reported did not survive the thermal cyclings for magnetic measurements. Later, M. H. Cohen (personal communication) reported similar anomalies in some Y-based oxides. In the absence of zero resistivity and evidence for the Meissner effect, the sharp resistance drops have been taken only as an indication of the possible existence of superconductivity at these unusually high temperatures. More recently, Chen et al. …


Science And Society Test X: Energy Conservation, David W. Hafemeister Apr 1987

Science And Society Test X: Energy Conservation, David W. Hafemeister

Physics

United States energy consumption has remained essentially constant at about 80 exajoules/year (75 quads/year) since the oil embargo of 1973–1974, while the GNP in constant dollars has increased by about 30%. This article will discuss the physics behind some of these improvements in end-use efficiency in such areas as: (i) buildings (scaling laws, "free-heat,'' superinsulated houses, thermal storage in large buildings, off-peak cooling), (ii) solar energy (passive, photovoltaics), (iii) utility load management ("smart meters,'' capital recovery fees, voltage control), (iv) appliances (life-cycle costs, refrigerators), and (v) lighting (isotopic enhancement).


Binding Of Fe2+ By Mammalian Ferritin, Richard B. Frankel, G. C. Papaefthymiou, G. D. Watt Mar 1987

Binding Of Fe2+ By Mammalian Ferritin, Richard B. Frankel, G. C. Papaefthymiou, G. D. Watt

Physics

An average of 140 Fe2+ ions bind to mammalian ferritin that has an average core content of 1876 Fe3+ ions per molecule. The Fe2+ ions enter the protein interior and exchange electrons with the core Fe3+ ions. A non-homogeneous model for the iron-containing core of ferritin is proposed.


Demountable Piezoelectric Transducer Holder For Use At Low Temperatures, Matthew J. Moelter, M. B. Manning, C. Ebaum Feb 1987

Demountable Piezoelectric Transducer Holder For Use At Low Temperatures, Matthew J. Moelter, M. B. Manning, C. Ebaum

Physics

We present a design for a piezoelectric transducer holder for use at low temperatures, which is easily constructed and assembled. Improved acoustic signals with "ringing" eliminated were reliably obtained. The standard problems of demountability, electrical integrity, and leak tightness in the presence of liquid helium at moderate pressures were resolved.


Mössbauer Spectroscopy Of Reduced Ferritin, Richard B. Frankel, G. C. Papaefthymiou, G. D. Watt Jan 1987

Mössbauer Spectroscopy Of Reduced Ferritin, Richard B. Frankel, G. C. Papaefthymiou, G. D. Watt

Physics

No abstract provided.


Effects Of Second Sound On Acoustic Trasmission At The Solid-Liquid 4He Interface, Matthew J. Moelter, M. B. Manning, C. Elbaum Oct 1986

Effects Of Second Sound On Acoustic Trasmission At The Solid-Liquid 4He Interface, Matthew J. Moelter, M. B. Manning, C. Elbaum

Physics

We have calculated the reflection and transmission coefficients of acoustic waves propagating across a solid-liquid interface of 4He, using an extension of the treatment of Castaing and Nozières in which we include pressure changes associated with second sound. These calculations account well for the experimental results obtained over the temperature range 0.83 K≤ T ≤1.46 K and provide an alternative explanation to the one we offered previously for the lack of agreement between experiment and the theory of Castaing and Nozières.


Rewarding Scientists Who Pursue And Discuss Physics In The Public Interest, David W. Hafemeister, Barbara Levi Aug 1986

Rewarding Scientists Who Pursue And Discuss Physics In The Public Interest, David W. Hafemeister, Barbara Levi

Physics

No abstract provided.


Science And Society Test Ix: Technical Means Of Verification, David W. Hafemeister Aug 1986

Science And Society Test Ix: Technical Means Of Verification, David W. Hafemeister

Physics

Technical means of monitoring are used to verify compliance to arms control treaties. Numerical estimates are developed in order to quantify some aspects of (1) nuclear testing (signatures, optical double pulse calibration, decoupling in cavities, and high-frequency components in seismic signals), (2) optical reconnaissance (films versus CCDs, air turbulence, adaptive optics, and digital image processing), (3) infrared (resolution and detection sensitivity), and (4) radar (synthetic aperture and missile coefficient).


Magnetite And Magnetotaxis In Algae, F. F. Torres De Araujo, M. A. Pires, Richard B. Frankel, C. E. M. Bicudo Aug 1986

Magnetite And Magnetotaxis In Algae, F. F. Torres De Araujo, M. A. Pires, Richard B. Frankel, C. E. M. Bicudo

Physics

Magnetotactic algae of the genus Anisonema (Euglenophyceae) have been isolated from a coastal mangrove swamp in northeastern Brazil. The magnetotactic response is based on a permanent magnetic dipole moment per cell ~7 10-10 emu. Each cell contains many magnetite (Fe3O4) particles organized in chains.


The Cal Poly House Doctor Lab, David W. Hafemeister Jul 1986

The Cal Poly House Doctor Lab, David W. Hafemeister

Physics

No abstract provided.


Magnetic Skeletons In Davy Jones' Locker, Richard B. Frankel Apr 1986

Magnetic Skeletons In Davy Jones' Locker, Richard B. Frankel

Physics

No Abstract.


Carrier-Concentration–Induced Ferromagnetism In Pbsnmnte, T. Story, R. R. Galazka, Richard B. Frankel, P. A. Wolff Feb 1986

Carrier-Concentration–Induced Ferromagnetism In Pbsnmnte, T. Story, R. R. Galazka, Richard B. Frankel, P. A. Wolff

Physics

The influence of charge-carrier concentration on the magnetic properties of the semimagnetic semiconductor [(PbTe)1-x(SnTe)x]1-y[MnTe] y (x=0.72, y=0.03) is reported. Magnetization, magnetic susceptibility, and specific heat have been measured. For carrier concentrations below p=3 x 1020 cm-3 the alloy is paramagnetic. For p≥3 x 1020 cm-3 an abrupt transition to a ferromagnetic phase is observed at helium temperatures. The ferromagnetic transition temperature increases with increasing p. This is the first demonstration of the effect of carrier concentration on the magnetic properties of semimagnetic semiconductors.


Plastic Deformation, Vacancy Diffusion, And Vacancy Delocalization In Bcc 3He, Matthew J. Moelter, M. B. Manning, C. Elbaum Feb 1986

Plastic Deformation, Vacancy Diffusion, And Vacancy Delocalization In Bcc 3He, Matthew J. Moelter, M. B. Manning, C. Elbaum

Physics

The plastic deformation of bcc 3He crystals has been studied near the melting curve, in the temperature range 0.65 K ≤T≤.17 K, and for strain rates, ɛ˙, from 2x10-6 to 2x10-4 sec-1. The resulting relations between strain rate and stress, at a given temperature, are accounted for in terms of dislocation climb and vacancy diffusion in the solid He. The temperature dependence of the strain rate at a given stress indicates that a nonclassical mechanism underlies the deformation process. The vacancy diffusion coefficient in bcc 3He, as a function of temperature, is deduced from …


Magnetite And Magnetotaxis In Bacteria And Algae, Richard B. Frankel Jan 1986

Magnetite And Magnetotaxis In Bacteria And Algae, Richard B. Frankel

Physics

We are using Mössbauer spectroscopy and magnetic measurements in conjunction with electrochemical, pH and optical spectroscopic measurements to study the mechanisms of iron containing core of these proteins.


Biological Effects Of Static Magnetic Fields, Richard B. Frankel Jan 1986

Biological Effects Of Static Magnetic Fields, Richard B. Frankel

Physics

No abstract provided.


Helium-4 Solid-Liquid Interface Mobility And Ultrasonic Energy Absorption Mechanisms, M. B. Manning, Matthew J. Moelter, C. Elbaum Dec 1985

Helium-4 Solid-Liquid Interface Mobility And Ultrasonic Energy Absorption Mechanisms, M. B. Manning, Matthew J. Moelter, C. Elbaum

Physics

The first measurements of acoustic reflection, together with acoustic transmission at the solid-liquid interface of 4He, are used to determine the total relative acoustic energy absorption at the interface as a function of temperature. Based on these results, a new mechanism for the temperature dependence of the kinetics of growth and interface mobility is proposed.


Physics Of Some Environmental Aspects Of Energy, David W. Hafemeister Nov 1985

Physics Of Some Environmental Aspects Of Energy, David W. Hafemeister

Physics

Approximate numerical estimates are carried out on the following environmental effects from energy production and conservation: (1) The greenhouse effect caused by increased CO2 in the atmosphere; (2) Loss of coolant accidents in nuclear reactors; (3) Increased radon concentrations in buildings with very low air infiltration rates; (4) Acid rain from the combustion of fossil fuels; and (5) Explosions of liquified natural gas (LNG).


Energy Conservation In Large Buildings, A. Rosenfeld, David W. Hafemeister Nov 1985

Energy Conservation In Large Buildings, A. Rosenfeld, David W. Hafemeister

Physics

As energy prices rise, newly energy aware designers use better tools and technology to create energy efficient buildings. Thus the U.S. office stock (average age 20 years) uses 250 kBTU/ft2 of resource energy, but the guzzler of 1972 uses 500 (up × 2), and the 1986 ASHRAE standards call for 100–125 (less than 25% of their 1972 ancestors). Surprisingly, the first real cost of these efficient buildings has not risen since 1972. Scaling laws are used to calculate heat gains and losses of buildings to obtain the ΔT(free) which can be as large as 15–30 °C (30–60 °F) for …


A Chronology Of Energy Conservation And Production, David W. Hafemeister Nov 1985

A Chronology Of Energy Conservation And Production, David W. Hafemeister

Physics

No abstract provided.


Emerging Technologies For Verification Of Arms Control Treaties, David W. Hafemeister Aug 1985

Emerging Technologies For Verification Of Arms Control Treaties, David W. Hafemeister

Physics

Progress in the technical means of monitoring to verify compliance to arms control treaties is discussed in the following areas: Real-time surveillance with charge-coupled devices in the visible and infrared; image enhancement with digital 1 image processing and with adaptive optics; imaging with radars based on satellites and on the ground; seismic monitoring with high frequency discrimination and with unattended in-country seismic stations; and nuclear weapons test monitoring with the global positioning satellite system.


Reduction Of Mammalian Ferritin, G. D. Watt, Richard B. Frankel, G. C. Papaefthymiou Jun 1985

Reduction Of Mammalian Ferritin, G. D. Watt, Richard B. Frankel, G. C. Papaefthymiou

Physics

Mammalian ferritin from horse spleen undergoes an electrochemical or chemical reduction reaction in which each iron atom present is reduced by one electron (2300 electrons per ferritin molecule containing 2300 Fe3+ ions). Midpoint potentials of -190 mV, -310 mV, and -416 mV were determined at pH 7.0, 8.0, and 9.0. This variation of potential with pH indicates that ≈ 2 H+ are transferred to the core for each Fe3+ reduced to Fe2+. Mössbauer measurements of partially reduced ferritin give spectra that consist of a ferric quadrupole doublet with a superposed ferrous quadrupole doublet. The relative …


A Birefringence Relaxation Determination Of Rotational Diffusion Of Magnetotactic Bacteria, Charles Rosenblatt, Richard B. Frankel, Richard P. Blakemore Mar 1985

A Birefringence Relaxation Determination Of Rotational Diffusion Of Magnetotactic Bacteria, Charles Rosenblatt, Richard B. Frankel, Richard P. Blakemore

Physics

The orientational relaxation of the magnetotactic bacterium Aquaspirillum magnetotacticum is observed by the decay of the optical birefringence upon switching off an aligning magnetic field. The data yield a rotational diffusion constant Dr ≅ 0.13 s1 and information about cell sizes that is consistent with optical microscopy data.


Mossbauer Spectroscopy Of Iron Biomineralization Products In Magnetotactic Bacteria, Richard B. Frankel, Georgia C. Papaefthymiou, Richard P. Blakemore Jan 1985

Mossbauer Spectroscopy Of Iron Biomineralization Products In Magnetotactic Bacteria, Richard B. Frankel, Georgia C. Papaefthymiou, Richard P. Blakemore

Physics

No abstract provided.


Microaerobic Conditions Are Required For Magnetite Formation Within Aquaspirillum Magnetotacticum, R. P. Blakemore, K. A. Short, D. A. Bazylinski, Charles Rosenblatt, Richard B. Frankel Jan 1985

Microaerobic Conditions Are Required For Magnetite Formation Within Aquaspirillum Magnetotacticum, R. P. Blakemore, K. A. Short, D. A. Bazylinski, Charles Rosenblatt, Richard B. Frankel

Physics

The amount of magnetite (Fe3O4) within magnetosomes of the microaerophilic bacterium Aquaspirillum magnetotacticum varies with oxygen and nitrogen supply. The development of optical methods for directly measuring cell magnetism in culture samples has enabled us to quantitate bacterial Fe3O4 yields. We measured final cell yields, average cell magnetic moments, and magnetosome yields of growing cells. Cultures were grown with NO3-, NH4+, or both, in sealed, unshaken vials with initial headspace Po2 values ranging from 0 (trace) to 21 kPa.

More than 50% of cells had detectable …