Biomedical subjects

R H Lamoreaux

Publications and source records attributed to R H Lamoreaux.

4 recordsLinked to original sources

PubMed1976

Viscosity of liquid metals: An interpretation.

The fluidity of liquid metals, like that of simple nonmetallic liquids, is a linear function of the ratio of unoccupied volume to intrinsic volume over long ranges as expressed by the equation varphi = B[(V/V(0)) - 1]. Values of V(0) obtained by extrapolating to varphi = 0 agree well with molal volumes of compact crystals at 20 degrees C calculated from densities.Values of the ratio varphi/[(V/V(0)) - 1] range from 27.0 for Na to 1.55 reciprocal centipoise for Ni. Viscosities at ratios of expansion V/V(0) = 1.10 vary linearly with squares of solubility parameters DeltaE(v)/V(0), where DeltaE(v) is molal energy of vaporization at the melting point. Viscosities at 10% expansion range from 0.037 cP for Na to 5.38 cP for Co, with some divergence for metals with values of eta in the neighborhood of unity. The good agreement in the case of the transition metals Cu, Fe, Co, and Ni we attribute to distribution of vector momentum among quasi-chemical bonds between d-electrons and vacant orbitals.

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PubMed1974

Diffusivity of Methane in a Mixture of CCl(4) and c-C(6)F(11)C(2)F(5) of the Critical Composition in the Region above the Temperature of Separation.

The diffusivity of CH(4) in a mixture of CCl(4) and c-C(6)F(11)C(2)F(5) of the critical composition in the region of temperature close to that of unmixing, decreases as in a homogeneous liquid from 36 degrees to about 32 degrees . It then passes through a minimum of 10(5)D approximately 4.15 cm(2)/sec at about 27.5 degrees , then rises to 10(5)D = 4.61 at 25.00 degrees , then steeply to 6.36 cm(2)/sec in the further drop of only 0.3 degrees to 24.71 degrees .

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PubMed1974

Diffusivity of gases in liquids.

Diffusion coefficients of H(2), Ne, N(2), Ar, CH(4), Cl(2), CF(4), C(2)H(6), SF(6), I(2), and isotopic CCl(4), all in CCl(4), determined at atmospheric pressure, are linear functions of temperature, converging to zero at the temperature where CCl(4) ceases to be fluid. The slopes of these lines increase with decreasing molecular cross-section of the diffusants, and with increasing entropy of expansion of the diffusants in CCl(4). Diffusivities in (C(4)F(9))(2)N, whose molecules are very large and three-armed, do not converge as temperature is decreased. Molecules of H(2), Ne, and, to a lesser extent, Ar, are able to diffuse in (C(4)F(9))(2)N even at temperatures where fluidity is low.

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PubMed1972

Fluidity: a general theory.

The equation varphi = B(V - V(o))/V(o), which reproduces the fluidity of simple liquids accurately over ranges between freezing and boiling points, is here shown to hold to pressures of at least 500 atm, and nearly to critical volumes. Fluidity can vary continuously above the critical region into that of compressed gas, where the parameter B becomes a function of temperature.The parameter V(o) is a "corresponding states" fraction of the critical molal volume. It is identical with the molal volume of the solid only in cases where molecules are free to rotate as they do in the liquid.Parameter B is a measure of the extent to which the external momentum that produces viscous flow is absorbed by the molecules of the liquid. Such damping can result from molecular mass, e.g., Ne, Ar, Kr; flexibility, normal alkanes; or rotational inertia, SiBr(4) against SiCl(4).

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