Spectrophotometric determination of tetracyclines and cephalosporins with ammonium vanadate

A spectrophotometric method for the determination of some tetracyclines as well as some cephalosporins is described. The drug is boiled with ammonium vanadate solution in sulphuric acid medium for 10 min and the absorbance of the colour developed is measured at 750 nm. The proposed method can be successfully applied to the determination of tetracycline hydrochloride, oxytetracycline hydrochloride, doxycycline hyclate, demeclocycline hydrochloride, chlortetracycline hydrochloride, cephalothin sodium, cephaloridine and cephapirin sodium. These drugs can be determined either in pure form or in pharmaceutical preparations.     

Spectrophotometric determination of phenothiazines, tetracyclines and chloramphenicol with sodium cobaltinitrite

A spectrophotometric method for determining some phenothiazines, some tetracyclines and chloramphenicol is described. Chlorpromazine hydrochloride, promazine hydrochloride, promethazine hydrochloride, perphenazine and fluphenazine hydrochloride are reacted with sodium cobaltinitrite in phosphoric acid. The red colour developed is measured at 530, 513, 515, 530 and 500 nm, respectively. Tetracycline hydrochloride, oxytetracycline hydrochloride, chlortetracycline hydrochloride, doxycycline hyclate and demeclocycline hydrochloride are reacted with the reagent in aqueous acetic acid. The yellow colour produced is measured at 256, 294, 262, 243 and 246 nm, respectively. Chloramphenicol is determined similarly to the tetracyclines after hydrolysis with 40% sodium hydroxide solution and the colour is measured at 240 nm. The proposed method has been successfully applied to the determination of these drugs in various pharmaceutical preparations.     

Kinetics and mechanism of oxidation of chromium(III)-tetraoxalylurea complex by periodate

A novel chromium(III) complex of tetraoxalylurea was prepared. In aqueous solutions, [Cr^III(H₂L)(H₂O)]⁺ (H₂L = diprotonated tetraoxalylurea) is oxidized by IO ₄ ^– according to the rate law

Interplay of information quantifiers and the modified Jaynes-Cummings model

The dynamics of the Buck and Sukumar model (B. Buck and C. V. Sukumar, Phys. Lett. A 81, 132 (1981)) is investigated using different semi-classical information-theory tools. Their interplay reveals somewhat unexpected features. A new signature for the classical-quantum barrier is encountered thereby.     

Correlation and entanglement of a three-level atom inside a dissipative cavity

We discuss the correlation and entanglement of a three-level atom with a single-mode quantized field in a coherent state inside a phase-damped cavity. We analyze the influence of dissipation on the quantum and classical entropy. It has been shown that the quantum, classical and nonextensive entropy are sensitive to any change in the initial state setting of the atom and the quantized field. The relation between the long lived entanglement and dissipation is observed. On the other hand, a short disentanglement can be generated through special values of the atomic motion parameter.     

Entanglement Sudden Death and Sudden Birth in Semiconductor Microcavities

We explore the dynamics of the entanglement in a semiconductor cavity QED containing a quantum well. We show the presence of sudden birth and sudden death for some particular sets of the system parameters.     

Solvent effect on the kinetics of oxidation of ferrocyanide by lodate in water-methanol mixtures

Summary The kinetics of oxidation of ferrocyanide by iodate ion in water-methanol solvent mixtures have been studied spectro-photometrically in the range 0.0 to 54wt% methanol, at five different temperatures ranging from 10 °C to 30 °C. The rate of reaction is increased with increasing of the methanol content in the mixture. Thermodynamic activation parameters have been calculated. An appropriate mechanism, consistent with the kinetic results, is suggested.     

Chemical studies on uranium extraction from concentrated phosphoric acid by using PC88A and DBBP mixture

The activity concentration of beryllium-7 (⁷Be), a naturally occurring cosmogenic radionuclide produced in the upper atmosphere, was measured in plants on the Loess plateau of China during the growing season of 2005. The ⁷Be mass activity concentration on July 27 ranged from 34.8 to 147.1 Bq kg⁻¹ in herbaceous plants, from 47.6 to 116.1 Bq kg⁻¹ in subshrubs, and from 15.7 to 56.8 Bq kg⁻¹ in crop plants. The ⁷Be mass and areal activity concentrations of a mixture of herbaceous plants increased from 66.8 to 288.7 Bq kg⁻¹ and from 0.7 to 46.5 Bq m⁻², respectively, during the growing season. On an areal basis, the fraction of ⁷Be in plants in the soil–plant system increased from 0.4 to 8.4% during the growing season. Positive linear correlations were found between the increases of ⁷Be mass and areal activity concentrations in the inter-sampling intervals and the amount of precipitation.