An MRCI investigation of the electronically excited states of difluorocarbene and its monovalent ions

The MRCI/CBS computational protocol was employed to describe the low-lying electronic states of CF₂ in excellent agreement with experiment. Also of interest for modeling the fluorocarbon plasmas are the difluorocarbene ions, and the geometries, adiabatic excitation energies and orbital characteristics of their electronically excited states were established. Most of the transitions leading to the excited states were found to be monoelectronic and, for the dipole-allowed ones, the oscillator strengths and radiative lifetimes were predicted to aid in the spectroscopic studies.     

Validation of an HPLC Method for the Determination of Valdecoxib and its Degradation Product: a Mixture of α- and β-n-Lactosyl Sulfonamide Anomers

An HPLC method has been developed for the separation of valdecoxib and a degradation product consisting of α and β-N-lactosyl sulfonamide, i.e. α and β anomers (SC-77852). Best results were achieved with a Chromolith Performance RP-18e column (100 mm × 4.6 mm), macropore size 2 μm, mesopore size 13 nm, with an eluent of methanol:water containing a 1% solution of TEA (36:64 v/v), pH 7.4 (adjusted with 85% orthophosphoric acid), at 22 °C. Detection was at 220 nm. The method was validated for its selectivity, linearity, precision (repeatability) and robustness. Quantitation and detection limits were determined for both valdecoxib and SC-77852. Method robustness was further evaluated by performing 2³ full factorial design experiments. The final step, optimisation of the variables, was performed using response surface design. The validated method was used for assay of valdecoxib and SC-77852 in Bextra^® film-coated tablets.     

Generation of the second harmonic in inhomogeneous magnetoactive plasma

The paper deals with the experimental study of conditions under which the second harmonic of a strong electromagnetic wave generating a spatially inhomogeneous plasma originates and exists. The second harmonic was detected by means of a h.f. probe inside the plasma and by a horn antenna outside the plasma. It was found that the beginning of generation of a strong second harmonic signal inside the plasma coincides with the overcoming of an evanescent layer and the free passage of the right-hand circularly polarized wave (RHCP wave) into an inhomogeneous plasma. Dependences of the second harmonic amplitude on the static magnetic field and the gas pressure are given.The authors wish to thank Dr. S. S. Moiseyev from FTI of Academy USSR (Kharkov) for valuable discussions concerning mechanisms of the second harmonic generation in an inhomogeneous plasma [4, 6]. To Ph.D.V. Kopeck); the authors would like to expresstheir thanks for many valuable discussions and his interest.     

Plasma lenses

An analysis is presented of the possibilites of focusing the microwave energy by means of a magnetoactive plasma. The basic parameters of a plasma lens are calculated, and the way a magnetoactive plasma may be used in the making of lenses with a variable focal length is pointed out.     

Localized orbitals,electric field gradients and diamagnetic shielding in hydrogen bonded systems

Ab-initio localized molecular orbitals are used to evaluate the diamagnetic shieldings and the electric field gradients in hydrogen bonded systems.     

On the possibility of the transformation of a soliton into the bound state of two excitons due to the exciton-photon interaction

This paper is concerned with the study of the probability of the soliton transformation, in the molecular chain, into the bound state of two excitons through the exciton-photon interaction.

It is established that this interaction, in general, is weak. In special cases, if the value of dynamical interaction becomes close to double the value of the resonant interaction between neighbouring molecules, the probability of the soliton transformation can be significant.