Crystal structure of beta-Mg2SiO4 - Crystal-chemical and geophysical implications
Crystal-chemical and geophysical implications concerning earth mantle phase transitions from beta magnesium silicate crystal structure
Moore, P. B.↗
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Role of water structure in various membrane systems
Water structure role in membrane systems, considering phase transitions and thermal anomalies in surface properties
Drost-Hansen, W.↗
Conductivity in liquid crystals
Photoresponse of liquid crystals at room temperature and dark conductivity changes at phase transitions
Kusabayashi, S.↗
Statistical thermodynamics of A-B-A block copolymers. I
A-B-A block copolymers statistical thermodynamics, describing postulated microstructure theoretical model for phase transition prediction
Leary, D. F.↗
Dynamic compression of enstatite
Shock wave data for Bamle enstatite in 60-480 kb range, considering Hugoniot elastic limit and phase transition produced shock front
Ahrens, T. J.↗
Apollo 12 clinopyroxenes - High temperature X-ray diffraction studies
High temperature phase transition and composition of Apollo 12 pigeonite/augite clinopyroxene crystal rock 12021 from X ray diffraction
Brown, G. E.↗
Earth physics and phase transformations program: A concept and proposal
A program to study the geophysical characteristics of the earth is presented as an integration of the different disciplines that constitute the earth sciences, through the foundation of a generalized geodynamic theory of earth physics. A program is considered for defining the physical constants of the earth's material which parametrize the hydrodynamic equation in the microscopic solid state behavior of the crystals of the lithosphere. In addition, in order to lay the foundation for a generalized theory in earth physics, specific research areas are considered, such as the nature of the kinetics of the phase transitions in mineral assemblages, the equilibrium thermodynamic properties of crystals which are major constituents of mineral assemblages, and the transport properties of pure crystals which are major constituents of mineral assemblages.
Bonavito, N. L.↗
Thermal release characteristics of spallogenic He, Ne, and Ar from the Carbo iron meteorite.
Analysis of the thermal release patterns of He, Ne, and Ar from samples of the Carbo iron meteorite, showing that virtually no fractionation of He 3, He 4, Ne 21, and Ar 38 occurs. Thus conclusions about iron meteorites based on measured noble gas ratios will be unaffected by gas loss, and measurement of these ratios cannot yield information about possible loss. Further, noble gas loss cannot explain the abnormal elemental and isotopic patterns observed in some iron meteorites, notably hexahedrites. The release of He and Ne was continuously observed throughout the stepwise heating sequence, and ratios of diffusion coefficients at two consecutive temperatures have been determined from measurements of the relative degassing rates at these temperatures at the time of temperature increase. Effective activation energies of 100 plus or minus 20 kcal/mol for both He 3 and Ne 21 are calculated from the diffusion coefficient ratios at temperatures above 1050 C. A sharp maximum at 750 C in both the effective activation energy and the gas release is correlated with the alpha, gamma-phase transition.
Nyquist, L. E.↗
Ultraviolet absorption spectra of mercuric halides.
The gas phase transitions of the mercuric halides were observed in the UV region by operating at temperatures above 400 K and at vapor pressures on the order of 0.5 mm. Spectral features exhibited by the chloride, bromide, and iodide of mercury correlate energetically with bands previously designated as intermolecular charge transfer transitions. The solution spectra of mercuric iodide and deep color of the crystals (if not due to some solid state interactions) indicate that this molecule may also have longer wavelength transitions.
Templet, P.↗
Electron paramagnetic resonance studies of a viscous nematic liquid crystal: Evidence counter to a second-order phase change
The ordering in a viscous, nematic, liquid crystal was studied using vanadyl acetyl acetonate and several nitroxides as paramagnetic probes. The ordering curve for VAAC at both K-band and X-band shows a slope discontinuity at a reduced temperature of 0.85. This discontinuity is caused by the tumbling time of the VAAC becoming comparable with the hyperfine splitting. The slope discontinuity is not present in the ordering curves of the nitroxides. The results are taken as evidence counter to the presence of a second-order phase transition.
Shutt, W. E.↗
On the physical basis of a theory of human thermoregulation.
Theoretical study of the physical factors which are responsible for thermoregulation in nude resting humans in a physical steady state. The behavior of oxidative metabolism, evaporative and convective thermal fluxes, fluid heat transfer, internal and surface temperatures, and evaporative phase transitions is studied by physiological/physical modeling techniques. The modeling is based on the theories that the body has a vital core with autothermoregulation, that the vital core contracts longitudinally, that the temperature of peripheral regions and extremities decreases towards the ambient, and that a significant portion of the evaporative heat may be lost underneath the skin. A theoretical basis is derived for a consistent modeling of steady-state thermoregulation on the basis of these theories.
Iberall, A. S.↗
Amplitude-steered, pseudophased antenna array
Beam may be smoothly scanned around ring array without instantaneous phase transitions while maintaining constant radiated power by gradually transferring power from receding element to element next to leading edge of driven segment, and by accomplishing antenna element switching during intervals when no power is being applied to elements being switched.
Johnson, C. C.↗
Phase equilibria in fluid mixtures at high pressures: The He-CH4 system
An experimental study of phase equilibria in the He-CH4 system was carried out over the temperature range 95 to 290 K and at pressures to 10,000 atm. The experimental results consist of equilibrium phase composition for twenty-eight isotherms in the region of coexistence of two fluid phases, together with the pressure-temperature trace of the three-phase boundary at which a CH4-rich solid phase is in equilibrium with the two fluid phases. The system exhibits a fluid-fluid phase separation which persists to temperatures and pressures beyond the range of this experiment. These results, together with those recently obtained for other binary systems, provide information about the form of phase diagrams for binary gas mixtures in the region of pressure induced phase transitions at high pressures. These findings are relevant to problems of deep atmosphere and interior structures in the outer planets.
Streett, W. B.↗
Handling, control, and servicing of Shuttle payloads
Consideration of the prospects for accommodation of various kinds of payloads in the Space Shuttle. The influence of the SOAR study on Shuttle design as it pertains to payload support and accommodation requirements is discussed. The effect of Shuttle payload requirements on the approach to payload attachment is illustrated, and the requirements governing payload accommodation during the early transitional phase and the fully operational phase of the Shuttle are outlined. A payload handling system for manipulating payloads to or from the payload bay is described which provides a local handling capability for delivery and retrieval of most spacecraft. Options regarding the integration of scientific experiments and payloads into the Shuttle are reviewed, and the use of the Shuttle for servicing spacecraft in orbit is discussed.
Schulte, L. O.↗
Energy source for comet outbursts
Development of a mechanism explaining the internal source of energy of comet outbursts. A mechanism is proposed which automatically provides a source of particulate matter which creates a huge surface area which contains a substantial percentage of amorphous ice, so that the phase transition of the amorphous ice to a cubic structure provides a release of energy which may be responsible for the outbursts observed in many comets. In addition, the volume into which the transition can propagate is estimated for a spherical comet with a radius of 5 km.
Patashnick, H.↗
Materials research at Stanford University
Research activity related to the science of materials is described. The following areas are included: elastic and thermal properties of composite materials, acoustic waves and devices, amorphous materials, crystal structure, synthesis of metal-metal bonds, interactions of solids with solutions, electrochemistry, fatigue damage, superconductivity and molecular physics and phase transition kinetics.
Source record↗
Tensile properties of palladium-silver alloys with absorbed hydrogen
The alloys 90Pd-10Ag, 80Pd-20Ag, 70Pd-30Ag, 60Pd-40Ag, and 50Pd-50Ag containing absorbed hydrogen were tested in tension. The results show the tensile properties to be independent of the phase transition. Also, hydrogen in the lattice does not necessarily cause embrittlement or poor elongation. The changes in the tensile properties appear dependent on the electron to atom site ratio.
Smith, R. J.↗
Thermodynamic properties of small aggregates of rare-gas atoms
The present work reports on the equilibrium thermodynamic properties of small clusters of xenon, krypton, and argon atoms, determined from a biased random-walk Monte Carlo procedure. Cluster sizes ranged from 3 to 13 atoms. Each cluster was found to have an abrupt liquid-gas phase transition at a temperature much less than for the bulk material. An abrupt solid-liquid transition is observed for thirteen- and eleven-particle clusters. For cluster sizes smaller than 11, a gradual transition from solid to liquid occurred over a fairly broad range of temperatures. Distribution of number of bond lengths as a function of bond length was calculated for several systems at various temperatures. The effects of box boundary conditions are discussed. Results show the importance of a correct description of boundary conditions. A surprising result is the slow rate at which system properties approach bulk behavior as cluster size is increased.
Etters, R. D.↗