Evaluation of the aquifer characteristics of the basaltic terrain of Maharashtra in India

The paper attempts to evaluate the permeability data obtained from 75 aquifer performance tests conducted on open wells tapping the water table aquifer of the basaltic lava flows spread over the three different basins of Maharashtra. The permeability has been computed by Thiem’s formula and the modified Theis non-equilibrium formula. The statistical analysis of the permeability data of the study basins,viz., Bhima, Godavari and Wardha, reveal a decrease in permeability range as one proceeds from the Bhima basin (low rainfall area) through the Godavari basin (assured rainfall area) to the high rainfall area of Wardha basin. The permeability frequency graphs of the three study basins reveal different hydrogeological characteristics for each.     

Note On the equality of star products

We study the problem of finding conditions for two star products of n vectors to be equal when the vectors in each star product are not linearly independent, and the problem of finding conditions for one star product to be zero. We reprove results of M. Marcus and J. Chollet in a very simple way. We present also some open problems.     

Surface complexation of DNA with insoluble monolayers. Influence of divalent counterions

DNA interacts with insoluble monolayers made of cationic amphiphiles as well as with monolayers of zwitterionic lipids in the presence of divalent ions. Binding to dioctadecyldimethylammonium bromide (DODAB) or distearoyl-sn-glycero-3-phosphocholine (DSPC) monolayers in the presence of calcium is accompanied by monolayer expansion. For the positively charged DODAB monolayer, this causes a decrease of surface potential, while an increase is observed for the DSPC monolayers. Binding to dipalmitoyl-sn-glycero-3-phosphocholine preserves most of the liquid expanded-liquid condensed coexistence region. The liquid condensed domains adopt an elongated morphology in the presence of DNA, especially in the presence of calcium. The interaction of DNA with phospholipid monolayers is ion specific: the presence of calcium leads to a stronger interaction than magnesium and barium. These results were confirmed by bulk complexation studies.     

Predicting hydration free energies of neutral compounds by a parametrization of the polarizable continuum model

A parametrization of the polarizable continuum model (PCM) is presented having the experimental hydration free energies of 215 neutral molecules as target. The cavitation and dispersion contributions were based on the Tu?on-Silla-Pascual-Ahuir (Tu?on; et al. Chem. Phys. Lett. 1993, 203, 289) and Floris-Tomasi (Floris, F.; Tomasi, J. J. Comput. Chem. 1989, 10, 616) expressions, respectively. Both the polar and nonpolar contributions were evaluated on the same solvent-excluding molecular surface that used unscaled Bondi atomic radii. The parametrization was provided for the HF, Xalpha, LSDA, B3LYP, and mPW1PW91 methods at the 6-31G(d) basis set, and the results are in fair agreement with the experimental data. For the sake of comparison, the PCM(UAHF) and our parametrization (PCM2), both at HF level, have produced DeltaG(PCM(UAHF)) = aDeltaGexp (a = 1.02 +/- 0.02, r = 0.945, sd = 0.987, Ftest = 1778) and DeltaG(PCM2) = aDeltaGexp (a = 0.95 +/- 0.02, r = 0.952, sd = 0.843, Ftest = 2070), respectively. The mean absolute deviations from experimental data were 0.67 and 0.68 kcal/mol for PCM(UAHF) and PCM2, respectively.     

The use of the final thermally stimulated discharge current technique to study the molecular movements around glass transition

During electric polarization charge is injected into the material. The structure is decorated with space charge and during the subsequent heating an apparent peak and the genuine peaks that are related to dipole randomization and charge detrapping are observed. The method is used here to analyze the molecular movements in polyimide in the temperature range from 293 to 623 K. Two weak relaxations have been observed around 337 K and around 402 K. The electrical conductivity changes with temperature in agreement with the Arrhenius law only below (W = (0.84 ± 0.03) eV ) and above ( W = (0.82 ± 0.03) eV) the temperature range where the β relaxation is observed. The variation of the electrical conductivity with temperature, in the range of the β relaxation, is controlled by the variation of the charge currier mobility with temperature and it shows a non-Arrhenius behavior. We suggest that the β₁ sub-glass relaxation is related to the rotation or oscillation of phenyl groups and the β₂ sub-glass relaxation is related to the rotation or oscillation of the imidic ring. At higher temperatures an apparent peak was observed. The relaxation time of the trapped charge, at 573 K, is high than 8895 s.     

Photophysical studies of alpha,omega-dicyano-oligothiophenes NC(C4H2S)nCN (n = 1-6)

The photophysics of six oligothiophenes end-capped with cyano groups (CNalphan) was investigated in solution at room and low temperature. The study comprises singlet-singlet and triplet-triplet absorption and emission spectra together with lifetimes and quantum yields for all the radiative and nonradiative processes. From the lifetimes and quantum yields, it was possible to extract the rate constants for all the processes. Singlet oxygen yields were also determined, revealing an efficient sensitization (SDelta approximately 1) of its formation by the triplet state of the CNalphan. The introduction of the cyano groups is found to decrease the energetic separation between the highest occupied molecular orbital and the lowest unoccupied molecular orbital, leading to a red shift of the absorption and the emission when compared with the unsubstituted counterparts, the alpha-oligothiophenes. Phosphorescence is only observed for the first member of the series, CNalpha1.     

Fluidized beds in flow analysis: use with ion-exchange separation for spectrophotometric determination of zinc in plant digests

A novel strategy for utilization of solid reagents in flow analysis is proposed. Establishment of diffuse and reproducible geometry enables the solid particles to be maintained in constant floating, reflux, and circulating motion inside a mini-chamber. This is efficiently accomplished with pulsed flows, a characteristic of multi-pumping flow systems. Drawbacks inherent in solid-phase packed columns, for example backpressure, preferential pathways, swelling, etc., and some limitations inherent in immobilized reagents are minimised. Spectrophotometric determination of zinc in plants was selected as an application of the technique. Dowex 1-X8 anionic resin was kept freely inside a mini-chamber. Zinc chloro-complexes were adsorbed on the moving particles and derivatization with zincon was performed after elution. Analytical figures of merit and the potential and limitations of the approach are discussed.