Gamma-irradiation effects on the electrical conductivity of some two dimensional complexes: RMnCl4, RCoCl4 and RMn0.5Co0.5Cl4;R = H_3 \mathop N\limits^ + /CH_2 /\mathop {{}_8N}\limits^ + H_3

DTA, dc-conductivity and thermoelectric power of the compounds RMnCl₄, RCoCl₄ and RMn_0.5Co_0.5Cl₄; \(R = H_3 \mathop N\limits^ + /CH_2 /\mathop {{}_8N}\limits^ + H_3 \) , have been measured over a temperature range of 300–500 K. Both DTA and dc-conductivity results showed the presence of many phase transitions in each one of the complexes investigated. The conductivity results were explained in terms of an electron hopping mechanism. The effect of γ-irradiation on the conductivity data and the type of crystal phases have been investigated and discussed.     

On the multiple-root problem when solving directly the nonlinear coupled-wave equations for two-wave mixing in a reflection geometry

A detailed analysis is given of the properties of the algebraic equations obtained when solving directly the nonlinear coupled-wave equations for degenerate two-wave mixing in a reflection geometry. An efficient method is developed for computing the appropriate root only amongst the multiple roots of these algebraic equations.     

Lacke, Anstrichstoffe

Ohne Zusammenfassung     

Improvement of opipramol base solubility by complexation with β-cyclodextrin

Opipramol (OPI), a tricyclic antidepressant and anxiolytic compound, is administered orally in the form of a dihydrochloride. Salt form of the drug has a higher solubility in water and hence bioavailability and stability. A similar effect can be achieved by closing the hydrophobic part of the drug molecule in the cyclodextrin cavity. The paper presents opipramol inclusion complexes with beta-cyclodextrin (β-CD) in 1:1 molar ratio. Studies on the formation of inclusion complexes were carried out both in solution and in the solid state. The formation and physicochemical characterisation of the complexes were determined by UV spectroscopic measurement (UV–vis), Fourier Transform Infrared (FTIR) Spectroscopy, ¹H Nuclear Magnetic Resonance (¹H NMR, 2D NOESY NMR), thermoanalytical methods (TGA – Termogravimetric analysis, DSC – differential scanning calorimetry), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The phase solubility profile with β-CD was classified as the A_N- type, indicating the formation of the inclusion complex with a drug.     

Automatic sample changer for neutron activation analysis at CDTN,Brazil

Journal of Radioanalytical and Nuclear Chemistry - An automatic sample changer was recently developed and installed in the Neutron Activation Analysis (NAA) Laboratory. The certified reference...     

Electronic surface states in superlattice with complex basis

The electronic structure of a semi-infinite superlattice (SL) with a complex basis consisting of two identical wells coupled via two different barriers is investigated. The possibility of the surface state existence for a periodic termination of the SL potential (i.e., without perturbing the SL potential at the surface) is shown for such a two-barrier basis, in contrast to the conventional one of single well and barrier. This main conclusion is based on analytical considerations, however, some numerical results for the GaAs/AlAs SL are also presented.     

Anisotropy Spectra of the Solvent-Sensitive Fluorophore 4-Dimethylamino-4′-Cyanostilbene in the Presence of Light Quenching

We examined the emission wavelength-dependent anisotropies of the solvent-sensitive fluorophore 4-dimethylamino-4-cyanostilbene (DCS) under conditions of light quenching by polarized time-delayed quenching pulses. Illumination on the long-wavelength side of the emission spectrum with time-delayed light pulses resulted in a progressive decrease in the emission anisotropy as the observation wavelength increased toward the stimulating wavelength. The anisotropy changes of DCS were most wavelength dependent when spectral relaxation occurred during the excited-state lifetime. Light quenching of DCS in a low-viscosity solvent revealed no wavelength-dependent anisotropies. Control measurements using a solvent-insensitive fluorophore did not show any wavelength-dependent anisotropy with light quenching. The data for DCS can be explained by a model which allows wavelength-selective quenching of the long-wavelength emission formed by time-dependent spectral relaxation. These results indicate that polarized light quenching can be used to study systems which display multiple emissions and/or time-dependent spectral shifts.