Abstract For a period of several years the philosopher science Hasok Chang has promoted various inter-related views including pluralism, pragmatism, and an associated view natural kinds. He also argued for what he calls persistence everyday terms in scientific view. claims that like phlogiston were never truly abandoned but became transformed into different concepts remain useful. On other hand...

Effects of temperature and percentage of organic modifier were studied on retention and selectivity in RP-HPLC using solvation parameter model. The system constants were determined by multiple linear regression analysis from experimental values in the retention factor for a group of different solutes with known descriptors by computer using the program SPSS/PC. The experimental results showed t...

The acidity constants (pKa) of thirty four (34) ;-substituted carboxylic acids in aqueous solution havebeen calculated using conductor-like polarizable continuum (C-PCM) solvation model. The gasphaseenergies at the Density Functional Theory (DFT-MPW1PW91) and solvation energies atHartree Fock (HF) are combined to estimate the pKa values which are very close to the experimentalvalues where, and ...

a competitive spectrophotometric method has been used for the study of complexation between cu2+, zn2+ and cd2+ (m) and 18-crown-6(18c6, b) in methanol using 4-(2-thiazolylazo) resorcinol (tar, hl) as the colorimetric complexant. absorption spectra of the species in the m-tar-18 c6 system at a various concentrations of 18c6 showed no formation of ternary complex, mlb, and the stoichiometry of t...

the effect of sds (0.03-0.07 m) and brij-35(0-0.003 m) concentrations and temperature on retention parameters of 30 solutes in micellar reversed- phase liquid chromatography systems were studied using solvation parameter model. the system constants were determined by multiple linear regression analysis from experimental values of the retention factors with known descriptors by computer using th...

Heterogeneous catalytic hydrogenation of cyclohexene, catalyzed by Pt/A1203, was carried out in thirteenvarious solvents (four alcoholic solvents, six aprotic polar solvents and three non polar solvents) at 25 °C.Single-parameter correlations of logk vs. normalized polarity parameter (ETN), hydrogen-bond acceptorbasicity (p), hydrogen-bond donor acidity (a) and dipolarity/polarizibility (it*) d...