Unstable Particles, Gauge Invariance and the Δ++ Resonance Parameters

The elastic and radiative ⁺ p scattering are studied in the framework of an effective Lagrangian model for the ⁺⁺ resonance and its interactions. The finite width effects of this spin-3/2 resonance are introduced in the scattering amplitudes through a complex mass scheme to respect electromagnetic gauge invariance. The resonant pole ( ⁺⁺) and background contributions ( ⁰, , , and neutron states) are separated according to the principles of the analytic S-matrix theory. The mass and width parameters of the ⁺⁺ obtained from a fit to experimental data on the total cross section are in agreement with the results of a model-independent analysis based on the analytic S-matrix approach. The magnetic dipole moment determined from the radiative ⁺ p scattering is nuclear magnetons.     

Determination of ethanol in beverages by flow injection, pervaporation and density measurements

A fast, clean and easy to automate flow injection-pervaporation method for the determination of ethanol in different beverages using density measurements is proposed. The method is based on separation of the ethanol from the sample using a pervaporation module; the analyte being collected in water as acceptor liquid. The density of this water-alcohol mixture is measured at the detector. After optimisation by either a univariate or multivariate approach as required, a linear range between 0 and 40% was established. Then, the assessment of the method versus a reference one was studied in terms of repeatability (0.12% v/v), reproducibility (0.32% v/v), detection limit (0.11% v/v) and traceability. The sample throughput was 15 samples h⁻¹. The method was in agreement with the reference methods used in the European Union.     

Catalytic polyaniline-supported electrodes for application in electrocatalysis

Ohne Zusammenfassung     

Static pressurised liquid extraction of nitrated polycyclic aromatic hydrocarbons from soils with on-line filtration-preconcentration prior to gas chromatography-mass spectrometry detection

Nitrated polycyclic aromatic hydrocarbons have been extracted from both spiked and natural contaminated soils by using static pressurised liquid extraction. The variables governing the extraction (namely, pressure, extraction time, temperature and number of static extraction cycles) have been optimised using the experimental design methodology. A laboratory-made pressurised liquid extractor has been used allowing its coupling to a filtration-preconcentration system through a flow injection interface, thus providing a partially automated approach. Gas chromatography with MS-MS ion preparation mode has been used for individual separation-identification/quantification providing both high selectivity (no interferences were observed) and sensitivity (detection limits of low pg). The comparison of the proposed approach with the reference EPA Method 3540 has shown that both methods provide similar efficiencies but with dramatic saving of time by the former (30 min vs. 24 h). The use of water as leaching agent avoids the use of organic solvents, thus providing an environmentally friendly method.     

(Z)-3-p-tolylsulfinylacrylonitriles as chiral dipolarophiles: reactions with diazoalkanes

[reaction: see text] The dipolarophilic reactivity of enantiopure (Z)-3-p-tolylsulfinylacrylonitriles (1) has been evaluated with diazoalkanes. 3-Cyanopyrazoles are obtained when R = H, but with R = alkyl (Bn, n-Bu, and t-Bu) only one cycloadduct (4 or 5) is formed in high yield under mild conditions, therefore evidencing a complete control of the regioselectivity and the endo/exo and pi-facial selectivities. These reactions are a new straightforward entry to the synthesis of pyrazolines and related structures and reveal the excellent dipolarophilic features of (Z)-sulfinylacrylonitriles.     

Calculated Infrared, Raman, and Rayleigh Properties of the CO(3) Molecule

Properties associated with the infrared, Rayleigh, and Raman spectra of the CO(3) molecule are calculated by the Hartree-Fock and M?ller-Plesset perturbation theory methods. Vibrational frequencies and infrared activities are found to be in agreement with the experiment and previous calculations. The values obtained for the Raman spectrum show a very sensitive dependence to the treatment of electron correlation. The OCO wag normal mode, unobserved in the IR experiment, is predicted to have a very small Raman scattering activity. Copyright 2000 Academic Press.     

Probing anomalous <Emphasis Type="Italic">Wtb</Emphasis> couplings in top pair decays

We investigate several quantities, defined in the decays of top quark pairs, which can be used to explore non-standard Wtb interactions. Two new angular asymmetries are introduced in the leptonic decay of top (anti)quarks. Both are very sensitive to anomalous Wtb couplings, and their measurement allows for a precise determination of the W helicity fractions. We also examine other angular and energy asymmetries, the W helicity fractions and their ratios, as well as spin correlation asymmetries, analysing their dependence on anomalous Wtb couplings and identifing the quantities which are most sensitive to them. It is explicitly shown that spin correlation asymmetries are less sensitive to new interactions in the decay of the top quark; therefore, when combined with the measurement of other observables, they can be used to determine the tt̄ spin correlation even in the presence of anomalous Wtb couplings. We finally discuss some asymmetries which can be used to test CP violation in tt̄ production and complex phases in the effective Wtb vertex.     

Defect identification in rods subject to forced vibrations using the spatial wavelet transform

Use of the wavelet transform (WT) to study the forced vibrations in a rod in order to detect the presence of a defect is proposed. The axial vibrations in an inhomogeneous rod, produced by the application of different forces, are simulated by the Network Simulation Method and the obtained response is analyzed with the WT. An analysis of the detection and location of defects for several applied forces and defects generated by locally changing density or stiffness of the rod is presented. A noise test was carried out to check the robustness of the technique in real situations.     

Determination of glyphosate and its metabolites in plant material by reversed‐polarity CE with indirect absorptiometric detection

A simple CE method for simultaneous determination of glyphosate and its metabolites (i.e. aminomethylphosphonic acid, glyoxylate, sarcosine and formaldehyde) in plants is reported here. A BGE of pH 7.5, 10% ACN, 7.5 mM phthalate, containing 0.75 mM hexadecyltrimethylammonium bromide as an electro‐osmotic flow modifier, an applied voltage of –20 kV and absorptiometric monitoring at 220 nm were the optimal chemical and instrumental parameters. The method, with development time 20 min, shows linear calibrations within the range 5–500 μg/mL (for all target analytes) with correlation coefficients between 0.999 and 0.998. It has been validated by application to samples of Lolium spp. The electroinjection mode hinders most interferents to enter the capillary, thus providing a clean electropherogram and making unnecessary long sample‐preparation steps.