A volumetric and NMR study of cyclodextrin-inhalation anesthetic complexes in aqueous solutions

The apparent molar volumes (Vϕ) of two anesthetics (halothane and forane) have been determined in water and in binary solvent (H2O + cyclodextrin) systems at 25 °C. The results show that the magnitudes of Vϕ are greater in ternary solutions than in the binary aqueous systems. The apparent molar volumes at infinite dilution (Vϕo) of halothane in ternary solutions are observed to depend on the following factors: (i) the magnitude of the binding constant (K1:1), (ii) the lipophilicity of the anesthetic, (iii) the mole ratio of the host/halothane system, and (iv) the topology (i.e., facial vs. inclusion) of the host/guest complex. The volumetric properties of the ternary systems have been analyzed in terms of the complexed and uncomplexed species by application of Young’s rule. The formation of 1:1 CD–halothane complexes was successfully modeled using a two-state model. The binding affinity of the various cyclodextrins toward halothane is listed in descending order as follows: DM-β-CD > HP-β-CD > β-CD > α-CD > TM-β-CD.

Representations on Hessenberg Varieties and Young's Rule

International audience We combinatorially construct the complex cohomology (equivariant and ordinary) of a family of algebraic varieties called regular semisimple Hessenberg varieties. This construction is purely in terms of the Bruhat order on the symmetric group. From this a representation of the symmetric group on the cohomology is defined. This representation generalizes work of Procesi, Stembridge and Tymoczko. Here a partial answer to an open question of Tymoczko is provided in our two main result. The first states, when the variety has multiple connected components, this representation is made up by inducing through a parabolic subgroup of the symmetric group. Using this, our second result obtains, for a special family of varieties, an explicit formula for this representation via Young's rule, giving the multiplicity of the irreducible representations in terms of the classical Kostka numbers. Nous construisons la cohomologie complexe (équivariante et ordinaire) d'une famille de variétés algébriques appelées variétés régulières semisimples de Hessenberg. Cette construction utilise exclusivement l'ordre de Bruhat sur le groupe symétrique, et on en déduit une représentation du groupe symétrique sur la cohomologie. Cette représentation généralise des résultats de Procesi, Stembridge et Tymoczko. Nous offrons ici une réponse partielle à une question de Tymoczko grâce à nos deux résultats principaux. Le premier déclare que lorsque la variété a plusieurs composantes connexes, cette représentation s'obtient par induction à travers un sous-groupe parabolique du groupe symétrique. Nous en déduisons notre deuxième résultat qui fournit, pour une famille spéciale de variétés, une formule explicite pour cette représentation par la règle de Young, et donne ainsi la multiplicité des représentations irréductibles en termes des nombres classiques de Kostka.

Thermodynamic properties of aqueous diethanolamine (DEA), N,N-dimethylethanolamine (DMEA), and their chloride salts: apparent molar heat capacities and volumes at temperatures from 283.15 to 328.15 K

Apparent molar heat capacities Cp,ϕ and apparent molar volumes Vϕ for aqueous diethanolamine (HOC2H4)2NH, diethanolammonium chloride (HOC2H4)2NH2Cl, N,N'-dimethylethanolamine (HOC2H4)(CH3)2N, and N,N'-dimethylethanolammonium chloride (HOC2H4)(CH3)2NHCl were determined from 283.15 to 328.15 K with a Picker flow microcalorimeter and vibrating tube densimeter. The experimental results have been analyzed in terms of Young's Rule with the Guggenheim form of the extended Debye-Hückel equation and appropriate corrections for chemical relaxation effects. These calculations lead to standard partial molar heat capacities and volumes for the neutral amines, (HOC2H4)2NH(aq) and (HOC2H4)(CH3)2N(aq), and the ions (HOC2H4)2NH2+(aq) and (HOC2H4)(CH3)2NH+(aq) over the experimental temperature range. Key words: standard partial molar volumes, standard partial molar heat capacities, diethanolamine, dimethyethanolamine, aqueous alkanolamine ionization.

Thermodynamics of aqueous EDTA systems: Apparent and partial molar heat capacities and volumes of aqueous EDTA4−, HEDTA3−, H2EDTA2−, NaEDTA3−, and KEDTA3− at 25 °C. Relaxation effects in mixed aqueous electrolyte solutions and calculations of temperature dependent equilibrium constants

Calorimetric and densimetric measurements have led to apparent molar heat capacities and volumes for aqueous solutions of the mixed electrolytes [(CH3)4N]4EDTA + (CH3)4NOH, Na4EDTA + NaOH, and K4EDTA + KOH, and single electrolytes Na2H2EDTA and [(CH3)4N]3[HEDTA] at 25 °C. We have analyzed these results in terms of Young's rule and Pitzer's ion interaction model to obtain standard state partial molar heat capacities and volumes of EDTA4−(aq), HEDTA3−(aq), H2EDTA2−(aq), NaEDTA3−(aq), and KEDTA3−(aq) at 25 °C. For these calculations it was also necessary to evaluate the "relaxation" contribution to the measured heat capacities of some solutions. The partial molar heat capacities obtained here have been used with enthalpies from previous investigations for calculations of several equilibrium constants over wide ranges of temperature; volumes can be used for similar calculations of the effects of pressure.