Thermodynamics of liquid mixtures of argon+ carbon monoxide

The heat of mixing of liquid argon (component 1) and liquid carbon monoxide has been measured by direct calorimetry for several mixtures of composition ranging from x₁ ? 0.2 to x₁ ? 0.8 at 85.79 K. At this temperature H^E is positive and an almost parabolic function of mole fraction, with a maximum value of H^E = 95.9 J mol^?1 at x₁ = 0.569.The experimental results are compared with those derived from the Gibbons-Rigby equation of state, and from conformal solution theory.     

Local-composition models and prediction of binary liquid-liquid binodal curves from heats of mixing

The temperature dependence of several local-composition models has been studied in conjunction with the Gibbs-Helmholtz identity. Binary heat-of-mixing data at temperatures near but above the critical solution temperature have been used to fit parameters obtained from excess-free-energy models in conjunction with the Gibbs-Helmholtz equation. These models, if the temperature dependence is adequate, should allow prediction of liquid-liquid equilibria (LLE) from the fitted parameters. The NRTL, UNIQUAC, and modified NRTL and UNIQUAC models (modified by inclusion of temperature-dependent parameters) seldom provide even qualitatively correct LLE predictions. A new local-composition model due to Wang and Chao (1983) yields reasonably good predictions for some systems but incorrect results for others. Reasons for these model inadequacies are discussed in terms of a local-composition model for the excess enthalpy which can be used to predict binodal curves accurately, including reasonably accurate values for the critical solution temperature, if reference excess-free-energy data at higher temperatures are available from VLE maesurements.     

4-Methyl- and 7-methylphthalan-1-one derivatives of mycophenolic acid : Use in establishing the distribution of acetate derived hydrogens

Incorporation of acetate-[2-¹⁴C, 2-³H] into mycophenolic acid has been shown by degradative experiments to be consistent with a starter effect indicative of a tetraketide precursor.     

Localized states in molecular auger spectra

The influence of the degree of localization of the two final holes on the Auger spectra of a simple diatomic molecule is analysed in detail and cases where such effects may be observed experimentally are discussed. The results are compared with studies of the valence band Auger spectra of solids.     

Preresonance Raman intensity studies in electron donor/acceptor complexes of tetracyanoethylene

The preresonance Raman intensity enhancement for the ν_C=C and ν_CN vibrations of TCNE complexed with toluene, benzene and fluorobenzene is established. Conclusions regarding the electronic states responsible for the effect are presented.     

The dertermination of trace elements in commerercial human serum albumin solutions by proton-induction x-ray emission spectrometry and neutron activation analysis

Particle-induced x-ray emission (p.i.x.e.) and neutron activation analysis (n.a.a.) are proposed for determining the trace element content of human serum albumin. Application of these methods to some commercial albumin solutions provided concentration data for up to 19 elements, most of which were present at a level below a few μg ml^-1. The precision of the p.i.x.e. technique, as determined by irradiating up to 20 targets from one sample, was about 3% for those elements where counting statistics were good. A comparison between the p.i.x.e. and n.a.a. results showed close agreement, indicating that p.i.x.e. can yield data which are accurate to within 10%. Neutron activation showed very good sensitivity for the elements producing long-lived nuclides (t_{$\text{1}\text{2}$} ? 3 days), but had rather high detection limits for the other elements, unless radiochemical separations were used.     

An investigation of the effect of the nearest surroundings on the formation of V Lα emission bands for solid solutions of rare earth orthovanadates—orthophosphates

The V Lα, P Kβ and O Kα X-ray emission spectra for solid solutions YVO₄—YPO₄ and EuVO₄—EuPO₄ have been studied. It is shown that with an increase in concentration of orthophosphate in a substitutional solid solution a hump appears in the low energy part of the V Lα spectrum, corresponding in energy to the P Kβ spectrum. The cluster calculation of the electronic structure of solid solutions YVO₄—YPO₄, carried out by the Extended Hückel method, explains this effect as due to the hybridization of V 3d and P 3p states when [PO₄ ] complexes are introduced into the orthovanadate tetrahedral lattice.     

1,2-Dihydroisoquinolines—XXI: Vinylogous meerwein salts

Treatment of 4-acyl-1,2-dihydroisoquinolines with the Meerwein reagent (triethyloxonium tetrafluoroborate) produces vinylogues of the ethoxyimminium cations in high yield. With a view to developing syntheses of 3-substituted isoquinoline derivatives, some reactions of these salts with nucleophilic reagents have been examined.