Etude par RMN du 13C d'un heterocycle derive du dibora-2,4 diazaro-1,3 benzene et du borazine correspondant

¹³C NMR spectra and complete assignment by means of coupled spectra and off resonance experiments, are reported for a new kind of organoboron heterocycle and the related borazine (o-CH₃C₆H₄NBCH₃)₃; π-charge densities, obtained from LCAO-MO Hückel calculations, are in reasonable agreement with experimental chemical shifts for the former compound.     

TOC versus UV spectrophotometry for wastewater quality monitoring

Total organic carbon (TOC) is one of the most important parameter for the knowledge of water and wastewater quality, because it concerns theoretically all organic compounds. Unfortunately, some restrictions with respect to TOC measurement must be considered, explaining that alternative procedures have been envisaged, among which UV spectrophotometry. Starting from a comparison of results between high temperature digestion and UV photo-oxidation techniques for some specific compounds and real wastewater samples, the work shows the complementary interest of using UV spectrophotometry either directly (with multiwavelength procedures) or after UV photo-oxidation.     

Analysis of atropine, its degradation products and related substances of natural origin by means of reversed-phase high-performance liquid chromatography

Chromatographic separation and quantification methods of tropa alkaloids were often described. In order to separate atropine from its degradation products ion-pair chromatography (IPC) has been frequently applied. Beside long equilibration times IPC often suffers from poor robustness. The aim of this study was to develop robust and simple HPLC methods for both stability testing of atropine solutions and limitation of related substances in atropine from plant material. Using a hydrophilic embedded RP18 column and a gradient elution gave baseline separation of all components.     

QCD asymptotics and kinematic thresholds in deep inelastic scattering

The Nachtmann moments of deep inelastic scattering structure functions are required by kinematics to contain a so far neglected threshold factor which is dependent on both n and q². Its presence significantly affects the “moment analysis” in the usual QCD phenomenology and it resolves the difficulties connected with improper threshold behavior of the “ξ-scaling” analysis of structure functions.     

Extended complexification method to study nonlinear passive control

Nonlinear Dynamics - The present research work aims to design a passive vibration control based on nonlinear energy pumping. An extended asymptotic approach is introduced based on the invariant...