In-beam γ spectroscopy using DIC with a radioactive Ne beam

A study of deep-inelastic and multi-nucleon transfer reactions to populate neutron-rich O, Ne and F nuclei is here presented. The reaction under analysis employed a beam of radioactive ²⁴Ne at 7.9 AMeV, provided by the SPIRAL facility at Ganil, impingin on a ²⁰⁸Pb target. The reaction products have been detected in the VAMOS spectrometer in coincidence with gamma rays measured by the EXOGAM array. Preliminary results here presented show a selectivity in the population of states of different nature.     

Air-broadening coefficients of the HO2 radical in the 2ν1 band measured using cw-CRDS

In this paper we present measurements of the air-broadening coefficients of HO₂ at room temperature in the 2ν₁ band around 1.5 microns. The HO₂ radicals were created by flash photolysis of SOCl₂ in a flow of O₂/CH₃OH mixtures. To observe air-broadening, N₂ (79%) and O₂ (21%) were added using calibrated flow controllers and a total pressure controller. The total pressure was monitored in parallel using a capacitive pressure gauge. Air-broadening coefficients at 296 K were determined for 34 absorption lines between 6631 and 6671 cm⁻¹. The air-broadening coefficients of HO₂ show a rotational dependence (decreasing from about 0.14 cm⁻¹/atm for N″ = 3 to about 0.09 cm⁻¹/atm for N″ = 10). No evidence for collisional narrowing was observed.     

Neural networks for Nyquist plots prediction in a nanocomposite polymer electrolyte (PEO–LiPF<Subscript>6</Subscript>–EC–CNT)

In this study, the Nyquist plots for nanocomposite polymer electrolyte system (polyethylene oxide (PEO)–lithium hexafluorophosphate (LiPF₆)–ethylene carbonate (EC)–carbon nanotube (CNT)), which was produced by using solution cast technique, were obtained using Bayesian neural network. First, to prepare the training and test set of the network, some results were experimental obtained and recorded. In the experiment, PEO, LiPF₆, EC, and CNT were mixed at various ratios. The effects of the chemical composition on the impedance spectra of polymer electrolyte system were investigated. In neural network training, different chemical composition and real impedance were used as inputs and imaginary impedance in the produced polymer electrolytes was used as outputs. After the training process, the test data were used to check system accuracy. As a result, the neural network was found successful for the prediction of imaginary impedance of nanocomposite polymer electrolyte system.     

Dispersion and attenuation of the eigenwaves for light propagation in heiicoidal liquid crystals

The dispersion curves and attenuation factors of the Bloch eigenwaves in heiicoidal liquid crystals (chiral smectic C and cholesterics) are calculated using the 4 × 4 characteristic matrix method. Four possible types of eigenmodes are seen to exist in the medium. The reflection peaks, which correspond to odd parts of the full pitch, are total reflection peaks, while those corresponding to even parts of the full pitch are composed of three branches at high incidence angles, where the outer branches are selective reflection and the central one is a total reflection peak. Selective reflection regions occur only at the edges of the Brillouin zones, while total reflections can occur anywhere inside the zones. The former are interpreted according to the coupled mode theory as resonant Bragg reflections, with the latter as exchange Bragg reflections. When the tilt direction exceeds the propagation direction, the central branch of the even sequence of peaks starts to be due to resonant Bragg reflections. The first order peak for cholesterics becomes strongly structured at large incidence angles.     

Colorimetric Procedure for the Microdetermination of the Antibilharzial Drug Praziquantel and its Applications to Pharmaceutical Formulations

 A procedure for the colorimetric assay of praziquantel has been developed. The method is based on the formation of charge-transfer complexes with p-chloranil (I), dichloronitrophenol (II), 2,3-dichloro-5,6 dicyano-p-benzoquinone (III), 7,7,8,8-tetracyanoquinodimethane (IV) and tetracyanoethylene (V) as π-acceptors to give highly coloured species. The coloured products are measured spectrophotometrically at 550, 425, 460, 844 and 393 nm for I, II, III, IV and V, respectively. Optimization of the different reaction conditions is described. The colour system obeyed Beer’s law in non-aqueous media in the concentration range 2.0–48 μg ml⁻¹. It was stable for at least 4.0 h. The detection limit was found to be 0.6 μg ml⁻¹. Applications of the procedure to the analysis of various pharmaceutical samples gave reproducible and accurate results. Further, the validity of the procedure was confirmed by applying the standard addition technique. The total average recovery was 100.2%. Received June 10, 2000. Revision December 23, 2000.     

Diethyl 1-(p-fluoro­phenyl)-5-oxo-3-(2-thienyl)­pyrrolidine-2,2-di­carboxyl­ate

In the title compound, C₂₀H₂₀FNO₅S, the pyrrolidine ring adopts an envelope conformation. The fluoro­phenyl and thio­phene rings are individually planar. The molecular and crystal structures are stabilized by intra- and intermolecular C—H⋯O interactions.     

Gas‐phase pyrolytic reaction of 3‐phenoxy and 3‐phenylsulfanyl‐1‐propanol derivatives: Kinetic and mechanistic study

3‐Phenoxy‐1‐propanols 1a–c and 3‐phenylsulfanyl‐1‐propanols 2a–c containing primary, secondary, and tertiary alcohols were prepared and subjected to gas‐phase pyrolysis in a static reaction system. Pyrolysis of 4‐phenyl‐1‐butanol 3 , 2‐methyl‐3‐phenyl‐1‐propanol 4 , and 2‐methyl‐3‐phenylpropanoic acid 5 was also studied, and results were compared with those obtained for compounds 1–3 . The pyrolytic reactions were homogeneous and followed a first‐order rate equation. Analysis of the pyrolysate showed the products to be phenol (from 1a to 1c ), thiophenol (from 2a to 2c ), and toluene (from 3 to 5 ) and carbonyl compounds. The kinetic results and product analysis of each of the nine investigated compounds are rationalized in terms of a plausible transition state for the elimination pathway. © 2007 Wiley Periodicals, Inc. 40: 51–58, 2008