Studies of mixtures

Bourquin J, Schmidli H, van Hoogevest P, Leuenberger H. Pitfalls of artificial neural networks (ANN) modelling technique for data sets containing outlier measurements using a study of mixture properties of a direct compressed tablet dosage form. Eur J Pharm Sci 1998 7 17-28. 

Several mixtures of hexanethiol capped gold nanopartides and triphenylene based discotic LCs have been studied. These mixtures display liquid crystal behavior (columnar mesophases) and an enhancement in the DC conductivity, due to the inclusion of gold nanoparticies into the matrix of the organic LC [70]. Other studies of mixtures of gold nanoparticies with mesogens indude a series of cholesteryl phenoxy alkanoates. The inclusion of the nanopartides does not change the inherent liquid crystal properties of the cholesteryl derivative but the mesophases are thermally stabilized [71]. 

Pulsed field gradient NMR has become a standard method for measurement of diffusion rates. Stilbs [272] and others have exploited in particular the FT version for the study of mixtures. An added advantage of PFG-NMR is that it can be employed to simplify complex NMR spectra. This simplification is achieved by attenuation of resonances based on the differential diffusion properties of components present in the mixture. 

However, for most studies, DTA has been mostly used in a qualitative sense as a means to determine the characteristic temperatures of thermally induced reactions. Owing to the experimental conditions used for its measurement, the technique is most useful for the characterization of materials that evolve corrosive gases during the heating process. The technique has been found to be highly useful as a means for compound identification based on the melting point considerations, and has been successfully used in the study of mixtures. 

In still other NMR studies of mixtures, Douglass and McBrierty have considered the homogeneity of polyvinylidene fluoride - poly methylmethacrylate blends.(38) Here the energy exchange between proton and fluorine magnetic spins is efficient only if the nuclei are adjacent. The results indicate, when taken around 40°C, that either the fluorine nuclei in a 40 polyvinylidene fluoride/60 poly methylmethacrylate blend are... 

Its precise basis in statistical mechanics makes the virial equation of state a powerful tool for prediction and correlation of thermodynamic properties involving fluids and fluid mixtures. Within the study of mixtures, the interaction second virial coefficient occupies an important position because of its relationship to the interaction potential between unlike molecules. On a more practical basis, this coefficient is useful in developing predictive correlations for mixture properties. 

Hermens, J., Canton, H., Janssen, P., and de Jong, R. Quantitative structure-activity relationships and toxicity studies of mixtures of chemicals with an anaesthetic potency acute lethal and sublethal toxicity to Daphnia magna, Aquat. Toxicol, 5(2) 143-154, 1984. 

Cook s discussion (Ref 2,pp 45-6) is translated into Russian in abbreviated form in the book of Andreev Belyaev (Ref 5, pp 146-48). Studies of mixtures of H2-O2-N2 H2-02 A, C2H2-O2 and others covering the range of initial pressure from below atmospheric to 50-l00atm showed that velocity frequently followed... 

Other examples are carcinogenicity studies on complex mixtures (petroleum middle distillates, foundry fumes, pesticides, heterocyclic amines, diesel exhaust, and solid particles) neurotoxicity studies of mixtures of solvents alone or in combination with exposure to physical factors and toxicity stndies of outdoor air pollutants, focusing... 

For experimental studies of mixtures, consideration is given to the possibility of changes in the physicochemical properties of the test substance during collection, storage, extraction, concentration and delivery. Chemical and toxicological interactions of the components of mixtures may result in nonlinear dose-response relationships. 

Since this discovery, termed spectral sensitization, many dyes have been evaluated in the drive to optimize performance. This has included the study of mixtures of dyes. It has been observed that dyes from several classes possess some activity but by far the most effective are the cyanines and related dyes. By 1969, one company alone had examined 15 000 dyes as spectral sensitizers (69MI11400). So, as would be expected, the literature on cyanine dyes is vast, much of it in the form of patents. Several comprehensive reviews on the chemistry of cyanine dyes (64HC(18)1, B-71MI11400) and on sensitizing dyes (B-77MI11401, 77HC(30)44l) have been published. 

These apparent liquid densities were derived through a study of mixtures containing methane and other heavier hydrocarbons and mixtures of ethane and other heavier hydrocarbons.2... 

Flash photolysis studies of mixtures of ozone and hydrogen (6,56) have shown that the reaction of 0(1D) atoms with hydrogen yields vibra-tionally excited OH radicals. Studies of ozone and hydrogen mixtures in the visible (35) and in the ultraviolet (94) have shown that water is formed and that the rate of ozone decomposition is increased in the presence of hydrogen. 

Applications of Thermodynamics to Phase Equilibria Studies of Mixtures... 

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