@article {2475, title = {High Temperature End of the So-Called "Koga Line": Anomalies in Temperature Derivatives of Heat Capacities}, journal = {Journal of Physical Chemistry B}, volume = {113}, number = {17}, year = {2009}, note = {ISI Document Delivery No.: 438BCTimes Cited: 0Cited Reference Count: 24Koga, Yoshikata Westh, Peter Moriya, Yosuke Kawasaki, Koji Atake, Tooru}, month = {Apr}, pages = {5885-5890}, type = {Article}, abstract = {The so-called "Koga line" is a collection of the loci of anomalies in various third derivatives of the Gibbs function, G, in the temperature-mole fraction field for aqueous solutions of nonelectrolytes. This splits the H2O-rich region into two, in each of which the molecular organization and interactions-we call it mixing scheme-is qualitatively different. In this work, we attempt to locate the high temperature end of the Koga line. This is a particularly interesting range of the boundary, since its extrapolation to zero Solute concentration provides information on possible temperature induced changes in the properties of pure water. To this end, we determine semi-isobaric heat capacities of aqueous 2-butoxyethanol by adiabatic calorimetry up to a maximum of 95 degrees C. The corrections due to vaporization were not applied due to the lack of required vapor pressure and thermal expansivity data. Furthermore, we measured directly the isobaric heat capacities per molar volume for aqueous I-propanol as well as 2-butoxyethanol by differential scanning calorimetry up to 120 degrees C at 3 atm. We then took one more temperature derivative of the respective heat capacity data. The resulting third derivative quantities from the former data showed step-type anomalies, while those from the latter negative peak-type anomalies. The loci of these anomalous points seem to point to about 70 degrees C at infinite dilution.}, keywords = {25-DEGREES-C, AQUEOUS 2-BUTOXYETHANOL, density, FLUCTUATION, METHANOL, MIXING SCHEME, PARTIAL MOLAR VOLUMES, pressure, TRANSITION, WATER-RICH REGION}, isbn = {1520-6106}, url = {://000265529900029}, author = {Koga,Yoshikata and Westh, P. and Moriya, Y. and Kawasaki, K. and Atake, T.} } @article {1231, title = {On the evaluation of the Kirkwood-Buff integrals of aqueous acetone mixtures}, journal = {Journal of Chemical Physics}, volume = {123}, number = {2}, year = {2005}, note = {ISI Document Delivery No.: 947NUTimes Cited: 14Cited Reference Count: 46}, month = {Jul}, pages = {11}, type = {Article}, abstract = {The Kirkwood-Buff integrals of acetone-water mixtures are determined using two experimental techniques: small-angle neutron scattering and vapor pressure measurements, in order to test the precision and reliability that can be achieved. The data are then compared with those previously reported by different authors, which tend to show considerable variation between them. The various possible sources of inaccuracies are pointed out, both from experimental origins and from the numerical treatment of the data. Comparison with recent simulation results allows to critically compare different models and provide some information about the microstructure of the aqueous mixture. (c) 2005 American Institute of Physics.}, keywords = {CONCENTRATION, FLUCTUATION, HENRYS LAW REGION, MOLECULAR-DYNAMICS, NEUTRON-SCATTERING, ORGANIC SOLUTES, TERT-BUTYL ALCOHOL, TETRAMETHYL UREA, TOTAL PRESSURE, WATER MIXTURES, X-RAY-SCATTERING}, isbn = {0021-9606}, url = {://000230653700023}, author = {Perera, A. and Sokolic, F. and Almasy, L. and Westh, P. and Koga,Yoshikata} }