7 research outputs found
Discovery of Strange Kinetics in Bulk Material: Correlated Dipoles in CaCu3Ti4O12
Dielectric spectroscopy of CaCu3Ti4O12 was performed spanning broad ranges of
temperature (10-300K) and frequency (0.5Hz-2MHz). We attribute the permittivity
step-fall to the evolution of Kirkwood-Fr\"oehlich dipole-correlations;
reducing the moment-density due to anti-parallel orienting dipoles, with
decreasing temperature. Unambiguous sub-Arrhenic dispersion of the associated
loss-peak reveals the prime role of strange kinetics; used to describe
nonlinearity-governed meso-confined/fractal systems, witnessed here for the
first time in a bulk material. Effective energy-scale is seen to follow thermal
evolution of the moment density, and the maidenly estimated correlation-length
achieves mesoscopic scale below 100K. Temperature dependence of correlations
reveals emergence of a new, parallel-dipole-orientation branch below 85K. Novel
features observed define a crossover temperature window connecting the
single-dipoles regime and the correlated moments. Conciling known results, we
suggest a fractal-like self-similar configuration of Ca/Cu-rich sub-phases;
resultant heterogeneity endowing CaCu3Ti4O12 its peculiar electrical behaviour.Comment: 19 pages, 5 figures, 44 reference
Development and Validation of a Discriminating In Vitro Dissolution Method for a Poorly Soluble Drug, Olmesartan Medoxomil: Comparison Between Commercial Tablets
A dissolution test for tablets containing 40 mg of olmesartan medoxomil (OLM) was developed and validated using both LC-UV and UV methods. After evaluation of the sink condition, dissolution medium, and stability of the drug, the method was validated using USP apparatus 2, 50 rpm rotation speed, and 900 ml of deaerated H2O + 0.5% sodium lauryl sulfate (w/v) at pH 6.8 (adjusted with 18% phosphoric acid) as the dissolution medium. The model-independent method using difference factor (f1) and similarity factor (f2), model-dependent method, and dissolution efficiency were employed to compare dissolution profiles. The kinetic parameters of drug release were also investigated. The obtained results provided adequate dissolution profiles. The developed dissolution test was validated according to international guidelines. Since there is no monograph for this drug in tablets, the dissolution method presented here can be used as a quality control test for OLM in this dosage form, especially in a batch to batch evaluation