Phenomenological optical model for p-4He elastic scattering

The results of a Dirac equation optical model analysis of p-⁴He elastic scattering data are reported. The optical potential obtained at 1029 MeV reproduces the systematics of p-⁴He data over the energy range from 560 to 1730 MeV.     

Managing marketing information: Nigel Piercy and Martin Evans Croom Helm,London, 1983, 223 pages

This note reports in a unified way some analytic results on the queuing system GI^X/M/1. It also corrects some erroneous results reported by Jensen and Paulson, and Krakowski.     

Determination of 112 halogenated pesticides using gas chromatography/mass spectrometry with selected ion monitoring

A procedure for the analysis of 112 halogenated pesticides that do not contain phosphorus has been developed. The procedure uses gas chromatography with a mass selective detector (GC-MSD), electron impact ionization, and selected-ion monitoring. This GC-MSD procedure provided lower limits of quantitation and provided increased confirmational data compared to the traditional element-selective GC procedures that are commonly used for the detection of this class of pesticides. These analytical improvements were demonstrated by the 25 pesticides that were detected at < or =50 ng/g levels in a variety of fruit and vegetable matrixes using this procedure that were missed by the traditional element selective GC procedures. Validation of the procedure was performed using 20 representative target pesticides with an acetone extraction and a solid-phase extraction cleanup. These target pesticides were used to demonstrate repeatability and linearity of the chromatographic response and recovery from fruit and vegetable matrixes.     

Charge inversion and neutralization–reionization mass spectra of some alkoxide ions

The charge inversion mass spectra of C₁ to C₃ alkoxide ions have been obtained using He, N₂ and O₂ as collision gases. The three collision gases show similar efficiencies for collisional charge inversion and produce similar mass spectra, although fewer high-energy oxenium ions are formed when O₂ and N₂ are used as collision gases. Using two collision cells and an intermediate deflector electrode the alkoxide ions have been neutralized in the first collision cell and the fast neutrals ionized in the second cell. The neutralization–reionization mass spectra obtained are similar to the direct charge-inversion mass spectra indicating that mainly alkoxyl radicals are produced, although, depending on the neutralization collision gas and the alkoxide ion studied, other neutrals are formed in small yields. Deuterium isotopic labelling has been used to show that the main fragmentation reactions of the unstable oxenium ions formed involve 1,1-elimination of H₂ or an alkane.     

The effect of ambient temperature on the propagation of nonadiabatic combustion waves

In this paper, we undertake an analytical and numerical investigation of the linear stability and properties of travelling nonadiabatic combustion wave for the case of nonzero ambient temperature. Here we consider premixed fuel with one-step exothermic reaction described by Arrhenius law. The speed of the front is estimated analytically by employing the matched asymptotic expansion approach and numerically using the shooting and relaxation methods. It is shown that increasing the ambient temperature results in the growth of both the flame speed and the region of existence of the travelling wave solutions in the parameter space. The linear stability of the travelling wave solution is investigated analytically by using the matched asymptotic expansion method and numerically by employing the Evans function approach. We demonstrate that by increasing the ambient temperature the stability of the propagating wave can also be increased.AMS subject classification: cation: 35K57, 80A25