New mixing rules in simple equations of state for representing vapour-liquid equilibria of strongly non-ideal mixtures

Huron, M.-J. and Vidal, J., 1979. New mixing rules in simple equations of state for representing vapour-liquid equilibria of strongly non-ideal mixtures. Fluid Phase Equilibria, 3: 255-271.Good correlations of vapour-liquid equilibria can be achieved by applying the same two-parameter cubic equation of state to both phases. The results primarily depend on the method used for calculating parameters and, for mixtures, on the mixing rule. True parameters are the covolume b and the energy parameter a/b. For this latter one, deviations from a linear weighting rule are closely connected to the excess free energy at infinite pressure. Thus any mixing rule gives a model for the excess free energy, or any accepted models for this property can be used as mixing rules.From the above, an empirical polynomial mixing rule is used for data smoothing and evaluation, while for practical work a local composition model is used. The mixing rule thus obtained can be reduced to the classical quadratic rule for some easily predicted values of the interaction energies. For highly polar systems, it includes three adjustable parameters. Using literature data, the new mixing rule is applied, in the low and high pressure range, to binary mixtures with one or two polar compounds, giving good data correlation and sometimes avoiding false liquid-liquid immiscibility.     

Atomic force microscopy study of beta-substituted-T7 oligothiophene films on mica: mechanical properties and humidity-dependent phases

The structural and mechanical properties of Langmuir-Blodgett monolayer and multilayer films of 3",4"-didecyl-5,2'; 5',2"; 5",2'; 5',2"; 5",2''; 5'',2"-heptathiophene-4'-acetic acid on mica have been studied by atomic force microscopy (AFM) as a function of humidity, temperature, and applied force. The molecules orient with the carboxylic acid group pointing toward the mica surface and expose the alkyl side chains to the air interface. As the load applied by the AFM tip increases, the film is compressed easily from an initial height of 2 to 1.2 nm. After compression the films can support much higher loads without loss of height. The state of aggregation of the molecules was found to be sensitive to the environmental humidity, which induced reversible changes. Annealing the samples with monolayer or multilayer films resulted in irreversible changes when the temperature exceeded approximately 100 degrees C.     

Multicomponent domino reaction from beta-ketoamides: highly efficient access to original polyfunctionalized 2,6-diazabicyclo[2.2.2]octane cores

We describe a new multicomponent domino reaction from beta-ketoamides, involved as substrates and as nucleophilic partners. We obtain highly functionalized and original 2,6-diazabicyclo[2.2.2]octane cores (2,6-DABCO) in a five-step one-pot sequence, which is fast, environmentally friendly, operationally simple to manage, and combines step- and atom-economic aspects.     

Molecular containers based on amphiphilic PS-b-PMVE dendrigraft copolymers: topology, organization, and aqueous solution properties

The synthesis, characteristics, and properties of amphipatic, water-soluble dendrigrafts, with a polystyrene core and polystyrene-b-poly(methyl vinyl ether) (PS-b-PMVE) diblock as external branches, are described. The dendrigrafts are observed by AFM and TEM as egglike or long cylindrical objects which can self-organize intramolecularly in segregated subdomains forming flowerlike or strings of flowerlike objects. In organic solvents the dendrigrafts behave as fully soluble isolated macromolecules and show in water a low critical solubility temperature (LCST) at t > 30 degrees C. The ability of the amphiphilic PS-b-PMVE dendrigrafts to complex and transport in water organic (pyrene) and metallo-organic (manganese tetraphenyl porphyrin) molecules is investigated. The possibility to stabilize the high oxidation state of metallo-porphyrin complexes through their encapsulation into the dendrigraft is shown.     

Mise en evidence de la polarisation d'une onde de surface par absorption atomique

Particular polarisation of surface waves is demonstrated using hyperfine dipolar magnetic transitions. We compare the relative intensities of F = 2, M = 2 ? F = 1, M = 1 andF = 2, M =-2 ? F = 1, M = -1 lines in the fundamental state of ⁸⁷Rb     

The use of extraction tests for deciding waste disposal options

Laboratory extraction test conditions do not accurately reflect the conditions within a land disposal facility. Current procedures lack the precision required for the results to be used as the basis for decision making.