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H J Maris

Publications and source records attributed to H J Maris.

5 recordsLinked to original sources

Superfluidity of grain boundaries and supersolid behavior.

When two communicating vessels are filled to a different height with liquid, the two levels equilibrate because the liquid can flow. We have looked for such equilibration with solid (4)He. For crystals with no grain boundaries, we see no flow of mass, whereas for crystals containing several grain boundaries, we detect a mass flow. Our results suggest that the transport of mass is due to the superfluidity of grain boundaries.

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Coalescence of viscous liquid drops.

We report on studies of the early stage of coalescence of two liquid drops. The drops were high viscosity silicon oil immersed in a water-alcohol mixture of the same density in order to eliminate the effects of gravity. The viscosity was sufficiently large that measurements could be made under the conditions of Stokes flow. Measurements were made of the radius of the neck between the drops as a function of the time from the onset of coalescence, and the results compared with theoretical predictions.

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Magnetic levitation-based Martian and Lunar gravity simulator.

Missions to Mars will subject living specimens to a range of low gravity environments. Deleterious biological effects of prolonged exposure to Martian gravity (0.38 g), Lunar gravity (0.17 g), and microgravity are expected, but the mechanisms involved and potential for remedies are unknown. We are proposing the development of a facility that provides a simulated Martian and Lunar gravity environment for experiments on biological systems in a well controlled laboratory setting. The magnetic adjustable gravity simulator will employ intense, inhomogeneous magnetic fields to exert magnetic body forces on a specimen that oppose the body force of gravity. By adjusting the magnetic field, it is possible to continuously adjust the total body force acting on a specimen. The simulator system considered consists of a superconducting solenoid with a room temperature bore sufficiently large to accommodate small whole organisms, cell cultures, and gravity sensitive bio-molecular solutions. It will have good optical access so that the organisms can be viewed in situ. This facility will be valuable for experimental observations and public demonstrations of systems in simulated reduced gravity.

Animals↗

Anomaly in the stability limit of liquid 3He.

We propose that the liquid-gas spinodal line of 3He reaches a minimum at 0.4 K. This feature is supported by our cavitation measurements. We also show that it is consistent with extrapolations of sound-velocity measurements. Speedy [J. Phys. Chem. 86, 3002 (1982)] previously proposed this peculiar behavior for the spinodal of water and related it to a change in sign of the expansion coefficient alpha, i.e., a line of density maxima. 3He exhibits such a line at positive pressure. We consider its extrapolation to negative pressure. Our discussion raises fundamental questions about the sign of alpha in a Fermi liquid along its spinodal.

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