In this work the acidity constants of Thiamine in water and water-Triton X-100 micelle media solutions, at 25 °C, have been determined spectrophotometrically. To evaluate the pH- absorbance data, a resolution based on the combination of soft-and hard-modeling is applied. The acidity constants of all related equilibria are estimated using the whole spectral fitting of the collected data to a...

We review properties of theories for the variation of gravitation and fine structure 'constants'. We highlight some general features of the cosmological models that exist in these theories with reference to recent quasar data that are consistent with time variation in the fine structure constant since a redshift of 3.5. The behaviour of a simple class of varying-alpha cosmologies is outlined in...

the aim of this research is to calculate the elastic constants and bulk modulus of cu-20 wt% ni random nanoalloy. the molecular dynamics simulation technique was used to calculate the mechanical properties in npt ensemble. the interaction between atoms as well as cohesive energy in the nanoalloy modeled systems was calculated by morse et al. two body potential. also the temperature of the syste...

the formation constants of the species formed in the systems h+ + mo(vi) + histidine and h+ +histidine have been determined at different aqueous solutions of methanol (0 - 45 % v/v) at 25 °c andconstant ionic strength (0.1 mol dm-3 sodium perchlorate), using a combination of spectrophotometricand potentiometric techniques. the composition of the complex species was determined by thecontinuous v...

The protonation constants of alanine and alanine methyl ester were determined in different aqueous solutions of 1,4-dioxane containing (0-50% v/v), using a potentiometric method at 25o C and constant ionic strength 0.1 mol.L-1 (NaCl). The protonation constants were analyzed in terms of Kamlet, Abboud and Taft (KAT) parameters. The results show that the effect of β is higher in comparison with t...

0 < A0 = A1 = A3 < A2 = A4 < 0.0319, and extremal functions for A0 and A2 exist, but extremal functions for A1, A3 and A4 they do not exist. This is a simple normal families argument; it also shows that extremal functions for A0 have the boundary of the ring {z : A0 < |z| < 1} as the natural boundary, and extremal functions for A2 have the unit circle as the natural boundary. The problem is to ...

The stability constants and complexation reaction between L-glutamine, L-arginine andglycine with Zn (II) , Co (II) and Ni (II) were studied potentiometrically in aqueous solution at25° C and μ=0.1 M KNO3. The overall stability constants log β´s of all species are obtained bycomputer refinement of pH-volume data using BEST computer program. Several models weretested and the lowest δFIT, the bes...

The protonation of different species of glycylisoleucine were studied in the pH range of 1.5 - 10 at25 °C using potentiometric technique. Investigations were performed in sodium perchlorate andtetraethylammonium iodide as background electrolytes at I (0.1, 0.2, 0.3, 0.4, 0.5, and 0.6) moldm-3. The parameters based on the protonation constants were calculated, and their dependenceson ionic stren...