NOPR Collection:

A fractal study of aliphatic compounds: A quantitative structure-property correlation through topological indices and bulk parameters

Wed, 01 Nov 1989 00:00:00 GMT

Title: A fractal study of aliphatic compounds: A quantitative structure-property correlation through topological indices and bulk parameters Authors: Mishra, B K; Guru, B K; Mishra, R K Abstract: Fractal nature of alkanes has been established. Fractal dimensionality (d_f) for different physicochemical properties has been generated through topological indices. Mathematically two independent equations have been proposed for short chain and long chain alkanes. Without searching for the critical carbon atom, the different physicochemical properties have been correlated and predicted through bulk parameters. Page(s): 927-931

Evidence for intramolecular energy transfer in photodecomposition of phenylalanine at different pH

Wed, 01 Nov 1989 00:00:00 GMT

Title: Evidence for intramolecular energy transfer in photodecomposition of phenylalanine at different pH Authors: Mukherjee, T; Mittal, L J; Mittal, J P Abstract: Absorption of 253.7 nm UV light by the aromatic chromophore in the O₂-free aqueous solutions of phenylalanine leads to the cleavage of the molecule forming ammonia and carbon dioxide, which have been quantitatively estimated within a pH range of ~ 2 to 12, using specific gas sensing electrodes. The yield Versus pH titration curve shows inflexion at ~pK_a for the NH group. A possible mechanism is postulated based on the known rate constants and the results are compared with those obtained by flash photolysis studies to elucidate intramolecular energy transfer. Page(s): 932-934

A new technique to measure flat band potential and barrier height at a desired surface charge of n- and p-semiconductors

Wed, 01 Nov 1989 00:00:00 GMT

Title: A new technique to measure flat band potential and barrier height at a desired surface charge of n- and p-semiconductors Authors: Sharon, Maheshwar; Prasad, B M; Basavaswaran, K Abstract: A new technique to measure surface conductivity has been developed. This technique which can be used with either a thin film or a pellet can also provide information on (i) flat-band potential at a desired pH, (ii) barrier height developed at the interface of semiconductor-electrolyte at any desired pH and (iii) flat-band potential at a desired surface charge present at the semiconductor. A model has been developed to explain the mechanism of surface conductivity of a semiconductor, such as ɑ-Fe₂O₃ or n-SnS or p-SnSe. Page(s): 935-941

Temperature of maximum density of aqueous solutions of aliphatic amines

Wed, 01 Nov 1989 00:00:00 GMT

Title: Temperature of maximum density of aqueous solutions of aliphatic amines Authors: Kaulgud, M V; Bhagde, V; Mate, V K Abstract: Temperature of maximum density (TMDs) in water at low concentrations for the seven amines: rnethyl-, ethyl-, n-propyl-, n-butyl-, t-butyl-, dimethyl-, and trimethyl amines have been measured and analyzed by applying hydrolysis correction to evaluate the structural part of the change in TMD (θ_str) for the unhydrolysed amine molecules. A correction procedure is described for which additional experimental data on TMDs of corresponding amine hydrochlorides have been obtained. The results of amines studied in this work do not fit in the conventional straight line relation (θ_str/x₂) = a + bx₂, which is obeyed by other non-electrolytes, like alcohols, which show positive intercepts (a) and negative slopes (b). The slopes of such plots for arnines are positive at low concentrations and negative at higher concentrations showing a broad maxima in between. The intercepts a which indicate the structure strengthening property of the solute are large negative for MeNH₂ and EtNH₂, slightly negative for n- PrNH₂, and positive for the rest of the amines. Comparison of a values of alcohols and amines indicate the difference in the amine-water and alcohol-water interactions. Page(s): 942-945