Analysis of serotonin in brain microdialysates using capillary electrophoresis and native laser-induced fluorescence detection

Serotonin or 5-hydroxytryptamine (5-HT) is a major neurotransmitter in the central nervous system. In this work, a method for analyzing 5-HT in brain microdialysis samples using a commercially available capillary electrophoresis (CE) system has been developed. A pH-mediated in-capillary preconcentration of samples was performed, and after separation by capillary zone electrophoresis, native fluorescence of 5-HT was detected by a 266 nm solid-state laser. The separation conditions for the analysis of 5-HT in standard solutions and microdialysates have been optimized, and this method has been validated on both pharmacological and analytical bases. Separation of 5-HT was performed using a 80 mmol/L citrate buffer, pH 2.5, containing 20 mmol/L hydroxypropyl-beta-cyclodextrin (HP-beta-CD) and +30 kV voltage. The detection limit was 2.5 x 10(-10) mol/L. This method allows the in vivo brain monitoring of 5-HT using a simple, accurate CE measurement in underivatized microdialysis samples.     

Precipitation of Energetic Electrons from the Earth’s Radiation Belt Stimulated by High-Power HF Radio Waves for Modification of the Midlatitude Ionosphere

Radiophysics and Quantum Electronics - Based on the results of the experiments performed in 2005–2010 within the framework of the Sura—DEMETER program, we analyze the features of the...     

MgI2‐Mediated Chemoselective Cleavage of Protecting Groups: An Alternative to Conventional Deprotection Methodologies

The scope of MgI₂ as a valuable tool for quantitative and mild chemoselective cleavage of protecting groups is described here. This novel synthetic approach expands the use of protecting groups, widens the concept of orthogonality in synthetic processes, and offers a facile opportunity to release compounds from solid supports.     

Spin-lattice coupling coefficients of Mn2+ ions in stacking faults of ZnS

The spin-lattice coupling coefficients (SLCC) of Mn²⁺ ions in axial sites PN of cubic ZnS crystals containing stacking faults have been measured by an uniaxial stress method. These coefficients were correctly interpreted in an ionic model by taking into account the Blume-Orbach mechanism adapted to a C_3v symmetry and a relativistic mechanism whose importance has been previously demonstrated. Finally, a comparison between the experimental SLCC's for Mn₂₊ in the cubic sites and two axial sites PN and AS due to stacking faults shows that they are roughly identical as predicted theoretically.     

EPR study of a ferroelastic phase transition in mixed (Gd,Nd) pentaphosphates

Very accurate EPR measurements have been performed below the critical temperature on Gd³⁺ impurities in NdP₅O₁₄. All experiments are interpreted in terms of a three-dimensional rotation of the principal axes of the D-tensor associated to each Gd³⁺ site. It is shown that this rotation can be associated to the rotations of the PO₄ tetrahedra appearing in the structure of NdP₅O₁₄.