Typical Solute Research Articles

Relaxation time effects in the stacking fault energy of noble metal alloys

The stacking fault energy, γ, in noble metal alloys can be expressed as a sum of two terms: δufe, the contribution due to the conduction electrons; and δuc, the contribution due to thed electrons. For noble metals and alloys δuc 〉 δufe while for multivalent normal metals δufe 〉 δuc. The theory is first discussed in terms of recent calculations of the pseudopotential form factors of the noble metals (Moriarty) and some of the typical solutes (Shaw). The theory is then extended in a phenomenological fashion to include the effects of a finite relaxation time, τ, of the conduction electrons. It is shown that, for concentrated noble metal alloys with the electron-to-atom ratio,Z 〉 1.14 and multivalent normal metals, δufe and hence γ will be dependent on both temperature and deformation through their effects on τ. An increase in τ results in a decrease in the magnitude of δufe. In the case of concentrated noble metal alloys this results in an increase in γ with increasing t while for multivalent normal metals γ decreases with increasing τ.

Properties of fatty acids in dispersions of emulsified lipid and bile salt and the significance of these properties in fat absorption in the pig and the sheep.

1. The behaviour of fatty acids in dilute bile salt solution and in dispersions of triglyceride in bile salt solution was examined. The properties of fatty acids in bile salt solution were defined in terms of their saturation ratio, and of the critical micellar concentration of bile salt for each fatty acid as solute. The partition of fatty acids between the oil phase and the micellar phase of the dispersions was defined as the distribution coefficientK M/O.The phases were separated by ultracentrifugation.2. Of the fatty acids examined, palmitic and stearic acids behaved in bile salt solution as typical non-polar solutes. Lauric, oleic and linoleic acids had properties similar to typical amphiphiles. The effectiveness of these and other amphiphiles was expressed in terms of an amphiphilic index.3. Thetrans-fatty acids, vaccenic acid and linolelaidic acid possessed solubility properties similar to theircis-isomers. The properties of elaidic acid were intermediate between those of the non-polar and the amphiphilic solutes.4. The distribution coefficients of fatty acids differed less significantly than their solubilities in bile salt solution, but were influenced to some extent by the composition of the oil phase.5. The effect of pH on the partition of fatty acids was similar for all fatty acids examined. There was a marked increase in the partition of fatty acids in the micellar phase as pH increased above 6.2.6. In the presence of Ca2+ions above a threshold concentration of I m-equiv./l. and at a pH higher than 6.4, the partition of stearic acid in the micellar phase of the bi-phasic system was restricted. No interaction of Ca2+ion and pH was observed with oleic acid.7. The effect of some amphiphiles on the distribution coefficient of stearic acid was examined. The capacity of lysolecithin to solubilize stearic acid in the micellar phase of dispersions was about twice that of I-mono-olein. The significance of the results in relation to fat absorption in the pig and the sheep is discussed.

Absorption of microwave radiation by solutions. Part 1.—Determination of electric dipole moments and relaxation times

An apparatus and experimental procedure are described for obtaining the complex electric permittivity of a liquid at microwave frequencies. Equations are developed by means of which the electric dipole moment and relaxation time of a polar molecule in a non-polar solvent may be evaluated from these measurements. Results are presented and discussed for five typical solutes in benzene solution at 25.0°.

Effect of Styrene Monomer on the Fluorescence Properties of Polystyrene

Fluorescence spectra and lifetimes have been studied for polystyrene samples having different average molecular weights and different concentrations of residual styrene monomer. The residual styrene monomer is fluorescent and acts as a typical fluorescent solute in a rigid medium. The fluorescence properties of polystyrene were found to be dependent on both the concentration of residual styrene monomer and, to a lesser extent, the average molecular weight.

Cryoscopic studies of solutions in 1‐4 dioxane

AbstractMeasurements of the freezing points of a series of solutions of organic compounds, mostly alcohols, in 1‐4 dioxane have been made and the corresponding molecular depressions calculated therefrom.In general, the results indicate progressive association of the solutes with increasing concentration of the solutions.Several solutes, however, notably ethyl and t‐butyl alcohols, appear to undergo solvation in dilute solution, whereas in concentrated solution the tendency to undergo association preponderates.Examination of solutes exhibiting this behavior in dioxane, when dissolved in other solvents having larger dielectric constants, fail to reveal a tendency to undergo solvation even in dilute solution.Association factors of typical solutes in dioxane as a solvent have been found to vary linearly with the concentration.